@wip

Signed-off-by: Michael Carroll <mjcarroll@intrinsic.ai>

rclcpp/CHANGELOG.rst

@@ -2,6 +2,26 @@
 Changelog for package rclcpp
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+20.0.0 (2023-04-13)
+-------------------
+* applied tracepoints for ring_buffer (`#2091 <https://github.com/ros2/rclcpp/issues/2091>`_)
+* Dynamic Subscription (REP-2011 Subset): Stubs for rclcpp (`#2165 <https://github.com/ros2/rclcpp/issues/2165>`_)
+* Add type_hash to cpp TopicEndpointInfo (`#2137 <https://github.com/ros2/rclcpp/issues/2137>`_)
+* Trigger the intraprocess guard condition with data (`#2164 <https://github.com/ros2/rclcpp/issues/2164>`_)
+* Minor grammar fix (`#2149 <https://github.com/ros2/rclcpp/issues/2149>`_)
+* Fix unnecessary allocations in executor.cpp (`#2135 <https://github.com/ros2/rclcpp/issues/2135>`_)
+* add Logger::get_effective_level(). (`#2141 <https://github.com/ros2/rclcpp/issues/2141>`_)
+* Remove deprecated header (`#2139 <https://github.com/ros2/rclcpp/issues/2139>`_)
+* Implement matched event (`#2105 <https://github.com/ros2/rclcpp/issues/2105>`_)
+* use allocator via init_options argument. (`#2129 <https://github.com/ros2/rclcpp/issues/2129>`_)
+* Fixes to silence some clang warnings. (`#2127 <https://github.com/ros2/rclcpp/issues/2127>`_)
+* Documentation improvements on the executor (`#2125 <https://github.com/ros2/rclcpp/issues/2125>`_)
+* Avoid losing waitable handles while using MultiThreadedExecutor (`#2109 <https://github.com/ros2/rclcpp/issues/2109>`_)
+* Hook up the incompatible type event inside of rclcpp (`#2069 <https://github.com/ros2/rclcpp/issues/2069>`_)
+* Update all rclcpp packages to C++17. (`#2121 <https://github.com/ros2/rclcpp/issues/2121>`_)
+* Fix clang warning: bugprone-use-after-move (`#2116 <https://github.com/ros2/rclcpp/issues/2116>`_)
+* Contributors: Barry Xu, Chris Lalancette, Christopher Wecht, Emerson Knapp, Michael Carroll, Tomoya Fujita, Yadu, mauropasse, methylDragon, ymski
+
 19.3.0 (2023-03-01)
 -------------------
 * Fix memory leak in tracetools::get_symbol() (`#2104 <https://github.com/ros2/rclcpp/issues/2104>`_)

rclcpp/CMakeLists.txt

@@ -49,16 +49,25 @@ set(${PROJECT_NAME}_SRCS
   src/rclcpp/detail/rmw_implementation_specific_subscription_payload.cpp
   src/rclcpp/detail/utilities.cpp
   src/rclcpp/duration.cpp
+  src/rclcpp/dynamic_typesupport/dynamic_message.cpp
+  src/rclcpp/dynamic_typesupport/dynamic_message_type.cpp
+  src/rclcpp/dynamic_typesupport/dynamic_message_type_builder.cpp
+  src/rclcpp/dynamic_typesupport/dynamic_message_type_support.cpp
+  src/rclcpp/dynamic_typesupport/dynamic_serialization_support.cpp
   src/rclcpp/event.cpp
   src/rclcpp/exceptions/exceptions.cpp
   src/rclcpp/executable_list.cpp
   src/rclcpp/executor.cpp
   src/rclcpp/executors.cpp
+  src/rclcpp/executors/executor_entities_collection.cpp
+  src/rclcpp/executors/executor_entities_collector.cpp
+  src/rclcpp/executors/executor_notify_waitable.cpp
   src/rclcpp/executors/multi_threaded_executor.cpp
   src/rclcpp/executors/single_threaded_executor.cpp
-  src/rclcpp/executors/static_executor_entities_collector.cpp
   src/rclcpp/executors/static_single_threaded_executor.cpp
   src/rclcpp/expand_topic_or_service_name.cpp
+  src/rclcpp/experimental/executors/events_executor/events_executor.cpp
+  src/rclcpp/experimental/timers_manager.cpp
   src/rclcpp/future_return_code.cpp
   src/rclcpp/generic_publisher.cpp
   src/rclcpp/generic_subscription.cpp

rclcpp/include/rclcpp/callback_group.hpp

@@ -93,11 +93,54 @@ public:
    *   determines whether a callback group is automatically added to an executor
    *   with the node with which it is associated.
    */
+  [[deprecated("Use CallbackGroup constructor with context function argument")]]
   RCLCPP_PUBLIC
   explicit CallbackGroup(
     CallbackGroupType group_type,
     bool automatically_add_to_executor_with_node = true);
 
+  /// Constructor for CallbackGroup.
+  /**
+   * Callback Groups have a type, either 'Mutually Exclusive' or 'Reentrant'
+   * and when creating one the type must be specified.
+   *
+   * Callbacks in Reentrant Callback Groups must be able to:
+   *   - run at the same time as themselves (reentrant)
+   *   - run at the same time as other callbacks in their group
+   *   - run at the same time as other callbacks in other groups
+   *
+   * Callbacks in Mutually Exclusive Callback Groups:
+   *   - will not be run multiple times simultaneously (non-reentrant)
+   *   - will not be run at the same time as other callbacks in their group
+   *   - but must run at the same time as callbacks in other groups
+   *
+   * Additionally, callback groups have a property which determines whether or
+   * not they are added to an executor with their associated node automatically.
+   * When creating a callback group the automatically_add_to_executor_with_node
+   * argument determines this behavior, and if true it will cause the newly
+   * created callback group to be added to an executor with the node when the
+   * Executor::add_node method is used.
+   * If false, this callback group will not be added automatically and would
+   * have to be added to an executor manually using the
+   * Executor::add_callback_group method.
+   *
+   * Whether the node was added to the executor before creating the callback
+   * group, or after, is irrelevant; the callback group will be automatically
+   * added to the executor in either case.
+   *
+   * \param[in] group_type The type of the callback group.
+   * \param[in] get_node_context Lambda to retrieve the node context when
+   *   checking that the creating node is valid and using the guard condition.
+   * \param[in] automatically_add_to_executor_with_node A boolean that
+   *   determines whether a callback group is automatically added to an executor
+   *   with the node with which it is associated.
+   */
+  RCLCPP_PUBLIC
+  explicit CallbackGroup(
+    CallbackGroupType group_type,
+    std::function<rclcpp::Context::SharedPtr(void)> get_node_context,
+    bool automatically_add_to_executor_with_node = true);
+
   /// Default destructor.
   RCLCPP_PUBLIC
   ~CallbackGroup();
@@ -137,14 +180,42 @@ public:
     return _find_ptrs_if_impl<rclcpp::Waitable, Function>(func, waitable_ptrs_);
   }
 
+  /// Get the total number of entities in this callback group.
+  /**
+   * \return the number of entities in the callback group.
+   */
+  RCLCPP_PUBLIC
+  size_t size() const;
+
+  /// Return a reference to the 'can be taken' atomic boolean.
+  /**
+   * The resulting bool will be true in the case that no executor is currently
+   * using an executable entity from this group.
+   * The resulting bool will be false in the case that an executor is currently
+   * using an executable entity from this group, and the group policy doesn't
+   * allow a second take (eg mutual exclusion)
+   * \return a reference to the flag
+   */
   RCLCPP_PUBLIC
   std::atomic_bool &
   can_be_taken_from();
 
+  /// Get the group type.
+  /**
+   * \return the group type
+   */
   RCLCPP_PUBLIC
   const CallbackGroupType &
   type() const;
 
+  /// Collect all of the entity pointers contained in this callback group.
+  /**
+   * \param[in] sub_func Function to execute for each subscription
+   * \param[in] service_func Function to execute for each service
+   * \param[in] client_func Function to execute for each client
+   * \param[in] timer_func Function to execute for each timer
+   * \param[in] waitable_fuinc Function to execute for each waitable
+   */
   RCLCPP_PUBLIC
   void collect_all_ptrs(
     std::function<void(const rclcpp::SubscriptionBase::SharedPtr &)> sub_func,
@@ -178,11 +249,24 @@ public:
   bool
   automatically_add_to_executor_with_node() const;
 
-  /// Defer creating the notify guard condition and return it.
+  /// Retrieve the guard condition used to signal changes to this callback group.
+  /**
+   * \param[in] context_ptr context to use when creating the guard condition
+   * \return guard condition if it is valid, otherwise nullptr.
+   */
+  [[deprecated("Use get_notify_guard_condition() without arguments")]]
   RCLCPP_PUBLIC
   rclcpp::GuardCondition::SharedPtr
   get_notify_guard_condition(const rclcpp::Context::SharedPtr context_ptr);
 
+  /// Retrieve the guard condition used to signal changes to this callback group.
+  /**
+   * \return guard condition if it is valid, otherwise nullptr.
+   */
+  RCLCPP_PUBLIC
+  rclcpp::GuardCondition::SharedPtr
+  get_notify_guard_condition();
+
   /// Trigger the notify guard condition.
   RCLCPP_PUBLIC
   void
@@ -234,6 +318,8 @@ protected:
   std::shared_ptr<rclcpp::GuardCondition> notify_guard_condition_ = nullptr;
   std::recursive_mutex notify_guard_condition_mutex_;
 
+  std::function<rclcpp::Context::SharedPtr(void)> get_context_;
+
 private:
   template<typename TypeT, typename Function>
   typename TypeT::SharedPtr _find_ptrs_if_impl(

rclcpp/include/rclcpp/dynamic_typesupport/dynamic_message.hpp

@@ -0,0 +1,70 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_HPP_
+#define RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_HPP_
+
+#include <rcl/allocator.h>
+#include <rcl/types.h>
+#include <rosidl_dynamic_typesupport/types.h>
+
+#include <memory>
+#include <string>
+
+#include "rclcpp/dynamic_typesupport/dynamic_message_type.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp"
+#include "rclcpp/macros.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+namespace dynamic_typesupport
+{
+
+/// Utility wrapper class for rosidl_dynamic_typesupport_dynamic_data_t
+/// STUBBED OUT
+class DynamicMessage : public std::enable_shared_from_this<DynamicMessage>
+{
+public:
+  RCLCPP_SMART_PTR_ALIASES_ONLY(DynamicMessage)
+
+  RCLCPP_PUBLIC
+  virtual ~DynamicMessage();
+
+protected:
+  // NOTE(methylDragon):
+  // This is just here to extend the lifetime of the serialization support
+  // It isn't actually used by the builder since the builder should compose its own support
+  //
+  // ... Though ideally it should be the exact same support as the one stored in the
+  // DynamicSerializationSupport
+  DynamicSerializationSupport::SharedPtr serialization_support_;
+
+  rosidl_dynamic_typesupport_dynamic_data_t rosidl_dynamic_data_;
+  bool is_loaned_;
+
+  // Used for returning the loaned value, and lifetime management
+  DynamicMessage::SharedPtr parent_data_;
+
+private:
+  RCLCPP_DISABLE_COPY(DynamicMessage)
+
+  RCLCPP_PUBLIC
+  DynamicMessage();
+};
+
+}  // namespace dynamic_typesupport
+}  // namespace rclcpp
+
+#endif  // RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_HPP_

rclcpp/include/rclcpp/dynamic_typesupport/dynamic_message_type.hpp

@@ -0,0 +1,64 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_TYPE_HPP_
+#define RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_TYPE_HPP_
+
+#include <rcl/allocator.h>
+#include <rosidl_dynamic_typesupport/types.h>
+
+#include <memory>
+#include <string>
+
+#include "rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp"
+#include "rclcpp/macros.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+namespace dynamic_typesupport
+{
+
+/// Utility wrapper class for `rosidl_dynamic_typesupport_dynamic_type_t`
+/// STUBBED OUT
+class DynamicMessageType : public std::enable_shared_from_this<DynamicMessageType>
+{
+public:
+  RCLCPP_SMART_PTR_ALIASES_ONLY(DynamicMessageType)
+
+  RCLCPP_PUBLIC
+  virtual ~DynamicMessageType();
+
+protected:
+  // NOTE(methylDragon):
+  // This is just here to extend the lifetime of the serialization support
+  // It isn't actually used by the builder since the builder should compose its own support
+  //
+  // ... Though ideally it should be the exact same support as the one stored in the
+  // `DynamicSerializationSupport`
+  DynamicSerializationSupport::SharedPtr serialization_support_;
+
+  rosidl_dynamic_typesupport_dynamic_type_t rosidl_dynamic_type_;
+
+private:
+  RCLCPP_DISABLE_COPY(DynamicMessageType)
+
+  RCLCPP_PUBLIC
+  DynamicMessageType();
+};
+
+}  // namespace dynamic_typesupport
+}  // namespace rclcpp
+
+#endif  // RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_TYPE_HPP_

rclcpp/include/rclcpp/dynamic_typesupport/dynamic_message_type_builder.hpp

@@ -0,0 +1,65 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_TYPE_BUILDER_HPP_
+#define RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_TYPE_BUILDER_HPP_
+
+#include <rcl/allocator.h>
+#include <rosidl_dynamic_typesupport/types.h>
+
+#include <memory>
+#include <string>
+
+#include "rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp"
+#include "rclcpp/macros.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+namespace dynamic_typesupport
+{
+
+/// Utility wrapper class for `rosidl_dynamic_typesupport_dynamic_type_builder_t *`
+/// STUBBED OUT
+class DynamicMessageTypeBuilder : public std::enable_shared_from_this<DynamicMessageTypeBuilder>
+{
+public:
+  RCLCPP_SMART_PTR_ALIASES_ONLY(DynamicMessageTypeBuilder)
+
+  RCLCPP_PUBLIC
+  virtual ~DynamicMessageTypeBuilder();
+
+protected:
+  // NOTE(methylDragon):
+  // This is just here to extend the lifetime of the serialization support
+  // It isn't actually used by the builder since the builder should compose its own support
+  //
+  // ... Though ideally it should be the exact same support as the one stored in the
+  // `DynamicSerializationSupport`
+  DynamicSerializationSupport::SharedPtr serialization_support_;
+
+  rosidl_dynamic_typesupport_dynamic_type_builder_t rosidl_dynamic_type_builder_;
+
+private:
+  RCLCPP_DISABLE_COPY(DynamicMessageTypeBuilder)
+
+  RCLCPP_PUBLIC
+  DynamicMessageTypeBuilder();
+};
+
+}  // namespace dynamic_typesupport
+}  // namespace rclcpp
+
+
+#endif  // RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_TYPE_BUILDER_HPP_

rclcpp/include/rclcpp/dynamic_typesupport/dynamic_message_type_support.hpp

@@ -0,0 +1,67 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_TYPE_SUPPORT_HPP_
+#define RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_TYPE_SUPPORT_HPP_
+
+#include <rcl/allocator.h>
+
+#include <rosidl_dynamic_typesupport/dynamic_message_type_support_struct.h>
+#include <rosidl_dynamic_typesupport/types.h>
+#include <rosidl_runtime_c/message_type_support_struct.h>
+#include <rosidl_runtime_c/type_description/type_description__struct.h>
+
+#include <memory>
+#include <string>
+
+#include "rclcpp/dynamic_typesupport/dynamic_message.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message_type.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp"
+
+#include "rclcpp/macros.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+namespace dynamic_typesupport
+{
+
+/// Utility wrapper class for `rosidl_message_type_support_t` containing managed
+/// STUBBED OUT
+class DynamicMessageTypeSupport : public std::enable_shared_from_this<DynamicMessageTypeSupport>
+{
+public:
+  RCLCPP_SMART_PTR_ALIASES_ONLY(DynamicMessageTypeSupport)
+
+  RCLCPP_PUBLIC
+  virtual ~DynamicMessageTypeSupport();
+
+protected:
+  DynamicSerializationSupport::SharedPtr serialization_support_;
+  DynamicMessageType::SharedPtr dynamic_message_type_;
+  DynamicMessage::SharedPtr dynamic_message_;
+
+  rosidl_message_type_support_t rosidl_message_type_support_;
+
+private:
+  RCLCPP_DISABLE_COPY(DynamicMessageTypeSupport)
+
+  RCLCPP_PUBLIC
+  DynamicMessageTypeSupport();
+};
+
+}  // namespace dynamic_typesupport
+}  // namespace rclcpp
+
+#endif  // RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_MESSAGE_TYPE_SUPPORT_HPP_

rclcpp/include/rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp

@@ -0,0 +1,60 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_SERIALIZATION_SUPPORT_HPP_
+#define RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_SERIALIZATION_SUPPORT_HPP_
+
+#include <rcl/allocator.h>
+#include <rosidl_dynamic_typesupport/api/serialization_support.h>
+#include <rosidl_dynamic_typesupport/types.h>
+
+#include <memory>
+#include <string>
+
+#include "rclcpp/macros.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+namespace dynamic_typesupport
+{
+
+/// Utility wrapper class for rosidl_dynamic_typesupport_serialization_support_t
+class DynamicSerializationSupport : public std::enable_shared_from_this<DynamicSerializationSupport>
+{
+public:
+  RCLCPP_SMART_PTR_ALIASES_ONLY(DynamicSerializationSupport)
+
+  RCLCPP_PUBLIC
+  explicit DynamicSerializationSupport(rcl_allocator_t allocator = rcl_get_default_allocator());
+
+  RCLCPP_PUBLIC
+  DynamicSerializationSupport(
+    const std::string & serialization_library_name,
+    rcl_allocator_t allocator = rcl_get_default_allocator());
+
+  RCLCPP_PUBLIC
+  virtual ~DynamicSerializationSupport();
+
+protected:
+  rosidl_dynamic_typesupport_serialization_support_t rosidl_serialization_support_;
+
+private:
+  RCLCPP_DISABLE_COPY(DynamicSerializationSupport)
+};
+
+}  // namespace dynamic_typesupport
+}  // namespace rclcpp
+
+#endif  // RCLCPP__DYNAMIC_TYPESUPPORT__DYNAMIC_SERIALIZATION_SUPPORT_HPP_

rclcpp/include/rclcpp/executor.hpp

@@ -19,6 +19,7 @@
 #include <cassert>
 #include <chrono>
 #include <cstdlib>
+#include <deque>
 #include <iostream>
 #include <list>
 #include <map>
@@ -29,28 +30,27 @@
 
 #include "rcl/guard_condition.h"
 #include "rcl/wait.h"
+#include "rclcpp/executors/executor_notify_waitable.hpp"
 #include "rcpputils/scope_exit.hpp"
 
 #include "rclcpp/context.hpp"
 #include "rclcpp/contexts/default_context.hpp"
 #include "rclcpp/guard_condition.hpp"
 #include "rclcpp/executor_options.hpp"
+#include "rclcpp/executors/executor_entities_collection.hpp"
+#include "rclcpp/executors/executor_entities_collector.hpp"
 #include "rclcpp/future_return_code.hpp"
-#include "rclcpp/memory_strategies.hpp"
-#include "rclcpp/memory_strategy.hpp"
 #include "rclcpp/node_interfaces/node_base_interface.hpp"
 #include "rclcpp/utilities.hpp"
 #include "rclcpp/visibility_control.hpp"
+#include "rclcpp/wait_set.hpp"
 
 namespace rclcpp
 {
 
-typedef std::map<rclcpp::CallbackGroup::WeakPtr,
-    rclcpp::node_interfaces::NodeBaseInterface::WeakPtr,
-    std::owner_less<rclcpp::CallbackGroup::WeakPtr>> WeakCallbackGroupsToNodesMap;
-
 // Forward declaration is used in convenience method signature.
 class Node;
+class ExecutorImplementation;
 
 /// Coordinate the order and timing of available communication tasks.
 /**
@@ -402,17 +402,6 @@ public:
   void
   cancel();
 
-  /// Support dynamic switching of the memory strategy.
-  /**
-   * Switching the memory strategy while the executor is spinning in another threading could have
-   * unintended consequences.
-   * \param[in] memory_strategy Shared pointer to the memory strategy to set.
-   * \throws std::runtime_error if memory_strategy is null
-   */
-  RCLCPP_PUBLIC
-  void
-  set_memory_strategy(memory_strategy::MemoryStrategy::SharedPtr memory_strategy);
-
   /// Returns true if the executor is currently spinning.
   /**
    * This function can be called asynchronously from any thread.
@@ -497,6 +486,11 @@ protected:
   static void
   execute_client(rclcpp::ClientBase::SharedPtr client);
 
+  /// Gather all of the waitable entities from associated nodes and callback groups.
+  RCLCPP_PUBLIC
+  void
+  collect_entities();
+
   /// Block until more work becomes avilable or timeout is reached.
   /**
    * Builds a set of waitable entities, which are passed to the middleware.
@@ -508,62 +502,6 @@ protected:
   void
   wait_for_work(std::chrono::nanoseconds timeout = std::chrono::nanoseconds(-1));
 
-  /// Find node associated with a callback group
-  /**
-   * \param[in] weak_groups_to_nodes map of callback groups to nodes
-   * \param[in] group callback group to find assocatiated node
-   * \return Pointer to associated node if found, else nullptr
-   */
-  RCLCPP_PUBLIC
-  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr
-  get_node_by_group(
-    const WeakCallbackGroupsToNodesMap & weak_groups_to_nodes,
-    rclcpp::CallbackGroup::SharedPtr group);
-
-  /// Return true if the node has been added to this executor.
-  /**
-   * \param[in] node_ptr a shared pointer that points to a node base interface
-   * \param[in] weak_groups_to_nodes map to nodes to lookup
-   * \return true if the node is associated with the executor, otherwise false
-   */
-  RCLCPP_PUBLIC
-  bool
-  has_node(
-    const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-    const WeakCallbackGroupsToNodesMap & weak_groups_to_nodes) const;
-
-  /// Find the callback group associated with a timer
-  /**
-   * \param[in] timer Timer to find associated callback group
-   * \return Pointer to callback group node if found, else nullptr
-   */
-  RCLCPP_PUBLIC
-  rclcpp::CallbackGroup::SharedPtr
-  get_group_by_timer(rclcpp::TimerBase::SharedPtr timer);
-
-  /// Add a callback group to an executor
-  /**
-   * \see rclcpp::Executor::add_callback_group
-   */
-  RCLCPP_PUBLIC
-  virtual void
-  add_callback_group_to_map(
-    rclcpp::CallbackGroup::SharedPtr group_ptr,
-    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-    WeakCallbackGroupsToNodesMap & weak_groups_to_nodes,
-    bool notify = true) RCPPUTILS_TSA_REQUIRES(mutex_);
-
-  /// Remove a callback group from the executor.
-  /**
-   * \see rclcpp::Executor::remove_callback_group
-   */
-  RCLCPP_PUBLIC
-  virtual void
-  remove_callback_group_from_map(
-    rclcpp::CallbackGroup::SharedPtr group_ptr,
-    WeakCallbackGroupsToNodesMap & weak_groups_to_nodes,
-    bool notify = true) RCPPUTILS_TSA_REQUIRES(mutex_);
-
   /// Check for executable in ready state and populate union structure.
   /**
    * \param[out] any_executable populated union structure of ready executable
@@ -574,33 +512,6 @@ protected:
   bool
   get_next_ready_executable(AnyExecutable & any_executable);
 
-  /// Check for executable in ready state and populate union structure.
-  /**
-   * This is the implementation of get_next_ready_executable that takes into
-   * account the current state of callback groups' association with nodes and
-   * executors.
-   *
-   * This checks in a particular order for available work:
-   *   * Timers
-   *   * Subscriptions
-   *   * Services
-   *   * Clients
-   *   * Waitable
-   *
-   * If the next executable is not associated with this executor/node pair,
-   * then this method will return false.
-   *
-   * \param[out] any_executable populated union structure of ready executable
-   * \param[in] weak_groups_to_nodes mapping of callback groups to nodes
-   * \return true if an executable was ready and any_executable was populated,
-   *   otherwise false
-   */
-  RCLCPP_PUBLIC
-  bool
-  get_next_ready_executable_from_map(
-    AnyExecutable & any_executable,
-    const WeakCallbackGroupsToNodesMap & weak_groups_to_nodes);
-
   /// Wait for executable in ready state and populate union structure.
   /**
    * If an executable is ready, it will return immediately, otherwise
@@ -618,39 +529,17 @@ protected:
     AnyExecutable & any_executable,
     std::chrono::nanoseconds timeout = std::chrono::nanoseconds(-1));
 
-  /// Add all callback groups that can be automatically added from associated nodes.
-  /**
-   * The executor, before collecting entities, verifies if any callback group from
-   * nodes associated with the executor, which is not already associated to an executor,
-   * can be automatically added to this executor.
-   * This takes care of any callback group that has been added to a node but not explicitly added
-   * to the executor.
-   * It is important to note that in order for the callback groups to be automatically added to an
-   * executor through this function, the node of the callback groups needs to have been added
-   * through the `add_node` method.
-   */
-  RCLCPP_PUBLIC
-  virtual void
-  add_callback_groups_from_nodes_associated_to_executor() RCPPUTILS_TSA_REQUIRES(mutex_);
-
   /// Spinning state, used to prevent multi threaded calls to spin and to cancel blocking spins.
   std::atomic_bool spinning;
 
   /// Guard condition for signaling the rmw layer to wake up for special events.
-  rclcpp::GuardCondition interrupt_guard_condition_;
+  std::shared_ptr<rclcpp::GuardCondition> interrupt_guard_condition_;
 
+  /// Guard condition for signaling the rmw layer to wake up for system shutdown.
   std::shared_ptr<rclcpp::GuardCondition> shutdown_guard_condition_;
 
-  /// Wait set for managing entities that the rmw layer waits on.
-  rcl_wait_set_t wait_set_ = rcl_get_zero_initialized_wait_set();
-
-  // Mutex to protect the subsequent memory_strategy_.
   mutable std::mutex mutex_;
 
-  /// The memory strategy: an interface for handling user-defined memory allocation strategies.
-  memory_strategy::MemoryStrategy::SharedPtr
-  memory_strategy_ RCPPUTILS_TSA_PT_GUARDED_BY(mutex_);
-
   /// The context associated with this executor.
   std::shared_ptr<rclcpp::Context> context_;
 
@@ -660,42 +549,39 @@ protected:
   virtual void
   spin_once_impl(std::chrono::nanoseconds timeout);
 
-  typedef std::map<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr,
-      const rclcpp::GuardCondition *,
-      std::owner_less<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr>>
-    WeakNodesToGuardConditionsMap;
+  /// Waitable containing guard conditions controlling the executor flow.
+  /**
+   * This waitable contains the interrupt and shutdown guard condition, as well
+   * as the guard condition associated with each node and callback group.
+   * By default, if any change is detected in the monitored entities, the notify
+   * waitable will awake the executor and rebuild  the collections.
+   */
+  std::shared_ptr<rclcpp::executors::ExecutorNotifyWaitable> notify_waitable_;
 
-  typedef std::map<rclcpp::CallbackGroup::WeakPtr,
-      const rclcpp::GuardCondition *,
-      std::owner_less<rclcpp::CallbackGroup::WeakPtr>>
-    WeakCallbackGroupsToGuardConditionsMap;
+  std::atomic_bool entities_need_rebuild_;
 
-  /// maps nodes to guard conditions
-  WeakNodesToGuardConditionsMap
-  weak_nodes_to_guard_conditions_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+  /// Collector used to associate executable entities from nodes and guard conditions
+  rclcpp::executors::ExecutorEntitiesCollector collector_;
 
-  /// maps callback groups to guard conditions
-  WeakCallbackGroupsToGuardConditionsMap
-  weak_groups_to_guard_conditions_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+  /// Waitset to be waited on.
+  rclcpp::WaitSet wait_set_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
 
-  /// maps callback groups associated to nodes
-  WeakCallbackGroupsToNodesMap
-  weak_groups_associated_with_executor_to_nodes_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+  /// Hold the current state of the collection being waited on by the waitset
+  rclcpp::executors::ExecutorEntitiesCollection current_collection_ RCPPUTILS_TSA_GUARDED_BY(
+    mutex_);
 
-  /// maps callback groups to nodes associated with executor
-  WeakCallbackGroupsToNodesMap
-  weak_groups_to_nodes_associated_with_executor_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+  /// Hold the current state of the notify waitable being waited on by the waitset
+  std::shared_ptr<rclcpp::executors::ExecutorNotifyWaitable> current_notify_waitable_
+  RCPPUTILS_TSA_GUARDED_BY(mutex_);
 
-  /// maps all callback groups to nodes
-  WeakCallbackGroupsToNodesMap
-  weak_groups_to_nodes_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
-
-  /// nodes that are associated with the executor
-  std::list<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr>
-  weak_nodes_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+  /// Hold the list of executables currently available to be executed.
+  std::deque<rclcpp::AnyExecutable> ready_executables_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
 
   /// shutdown callback handle registered to Context
   rclcpp::OnShutdownCallbackHandle shutdown_callback_handle_;
+
+  /// Pointer to implementation
+  std::unique_ptr<ExecutorImplementation> impl_;
 };
 
 }  // namespace rclcpp

rclcpp/include/rclcpp/executors.hpp

@@ -21,6 +21,7 @@
 #include "rclcpp/executors/multi_threaded_executor.hpp"
 #include "rclcpp/executors/single_threaded_executor.hpp"
 #include "rclcpp/executors/static_single_threaded_executor.hpp"
+#include "rclcpp/experimental/executors/events_executor/events_executor.hpp"
 #include "rclcpp/node.hpp"
 #include "rclcpp/utilities.hpp"
 #include "rclcpp/visibility_control.hpp"

rclcpp/include/rclcpp/executors/executor_entities_collection.hpp

@@ -0,0 +1,213 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__EXECUTORS__EXECUTOR_ENTITIES_COLLECTION_HPP_
+#define RCLCPP__EXECUTORS__EXECUTOR_ENTITIES_COLLECTION_HPP_
+
+#include <deque>
+#include <functional>
+#include <unordered_map>
+#include <vector>
+
+#include <rclcpp/any_executable.hpp>
+#include <rclcpp/node_interfaces/node_base.hpp>
+#include <rclcpp/callback_group.hpp>
+#include <rclcpp/executors/executor_notify_waitable.hpp>
+#include <rclcpp/visibility_control.hpp>
+#include <rclcpp/wait_result.hpp>
+#include <rclcpp/wait_set.hpp>
+
+namespace rclcpp
+{
+namespace executors
+{
+
+/// Structure to represent a single entity's entry in a collection
+template<typename EntityValueType>
+struct CollectionEntry
+{
+  /// Weak pointer to entity type
+  using EntityWeakPtr = typename EntityValueType::WeakPtr;
+  /// Shared pointer to entity type
+  using EntitySharedPtr = typename EntityValueType::SharedPtr;
+
+  /// The entity
+  EntityWeakPtr entity;
+
+  /// If relevant, the entity's corresponding callback_group
+  rclcpp::CallbackGroup::WeakPtr callback_group;
+};
+
+/// Update a collection based on another collection
+/*
+ * Iterates update_from and update_to to see which entities have been added/removed between
+ * the two collections.
+ *
+ * For each new entry (in update_from, but not in update_to),
+ *   add the entity and fire the on_added callback
+ * For each removed entry (in update_to, but not in update_from),
+ *   remove the entity and fire the on_removed callback.
+ *
+ *  \param[in] update_from The collection representing the next iteration's state
+ *  \param[inout] update_to The collection representing the current iteration's state
+ *  \param[in] on_added Callback fired when a new entity is detected
+ *  \param[in] on_removed Callback fired when an entity is removed
+ */
+template<typename CollectionType>
+void update_entities(
+  const CollectionType & update_from,
+  CollectionType & update_to,
+  std::function<void(const typename CollectionType::EntitySharedPtr &)> on_added,
+  std::function<void(const typename CollectionType::EntitySharedPtr &)> on_removed
+)
+{
+  for (auto it = update_to.begin(); it != update_to.end(); ) {
+    if (update_from.count(it->first) == 0) {
+      auto entity = it->second.entity.lock();
+      if (entity) {
+        on_removed(entity);
+      }
+      it = update_to.erase(it);
+    } else {
+      ++it;
+    }
+  }
+  for (auto it = update_from.begin(); it != update_from.end(); ++it) {
+    if (update_to.count(it->first) == 0) {
+      auto entity = it->second.entity.lock();
+      if (entity) {
+        on_added(entity);
+      }
+      update_to.insert(*it);
+    }
+  }
+}
+
+/// A collection of entities, indexed by their corresponding handles
+template<typename EntityKeyType, typename EntityValueType>
+class EntityCollection
+  : public std::unordered_map<const EntityKeyType *, CollectionEntry<EntityValueType>>
+{
+public:
+  /// Key type of the map
+  using Key = const EntityKeyType *;
+
+  /// Weak pointer to entity type
+  using EntityWeakPtr = typename EntityValueType::WeakPtr;
+
+  /// Shared pointer to entity type
+  using EntitySharedPtr = typename EntityValueType::SharedPtr;
+
+  /// Update this collection based on the contents of another collection
+  /**
+   * Update the internal state of this collection, firing callbacks when entities have been
+   * added or removed.
+   *
+   * \param[in] other Collection to compare to
+   * \param[in] on_added Callback for when entities have been added
+   * \param[in] on_removed Callback for when entities have been removed
+   */
+  void update(
+    const EntityCollection<EntityKeyType, EntityValueType> & other,
+    std::function<void(const EntitySharedPtr &)> on_added,
+    std::function<void(const EntitySharedPtr &)> on_removed)
+  {
+    update_entities(other, *this, on_added, on_removed);
+  }
+};
+
+/// Represent the total set of entities for a single executor
+/**
+ * This allows the entities to be stored from ExecutorEntitiesCollector.
+ * The structure also makes in convenient to re-evaluate when entities have been added or removed.
+ */
+struct ExecutorEntitiesCollection
+{
+  /// Collection type for timer entities
+  using TimerCollection = EntityCollection<rcl_timer_t, rclcpp::TimerBase>;
+
+  /// Collection type for subscription entities
+  using SubscriptionCollection = EntityCollection<rcl_subscription_t, rclcpp::SubscriptionBase>;
+
+  /// Collection type for client entities
+  using ClientCollection = EntityCollection<rcl_client_t, rclcpp::ClientBase>;
+
+  /// Collection type for service entities
+  using ServiceCollection = EntityCollection<rcl_service_t, rclcpp::ServiceBase>;
+
+  /// Collection type for waitable entities
+  using WaitableCollection = EntityCollection<rclcpp::Waitable, rclcpp::Waitable>;
+
+  /// Collection type for guard condition entities
+  using GuardConditionCollection = EntityCollection<rcl_guard_condition_t, rclcpp::GuardCondition>;
+
+  /// Collection of timers currently in use by the executor.
+  TimerCollection timers;
+
+  /// Collection of subscriptions currently in use by the executor.
+  SubscriptionCollection subscriptions;
+
+  /// Collection of clients currently in use by the executor.
+  ClientCollection clients;
+
+  /// Collection of services currently in use by the executor.
+  ServiceCollection services;
+
+  /// Collection of guard conditions currently in use by the executor.
+  GuardConditionCollection guard_conditions;
+
+  /// Collection of waitables currently in use by the executor.
+  WaitableCollection waitables;
+
+  /// Check if the entities collection is empty
+  /**
+   * \return true if all member collections are empty, false otherwise
+  */
+  bool empty() const;
+
+  /// Clear the entities collection
+  void clear();
+};
+
+/// Build an entities collection from callback groups
+/**
+ * Iterates a list of callback groups and adds entities from each valid group
+ *
+ * \param[in] callback_groups List of callback groups to check for entities
+ * \param[inout] colletion Entities collection to populate with found entities
+ */
+void
+build_entities_collection(
+  const std::vector<rclcpp::CallbackGroup::WeakPtr> & callback_groups,
+  ExecutorEntitiesCollection & collection);
+
+/// Build a queue of executables ready to be executed
+/**
+ * Iterates a list of entities and adds them to a queue if they are ready.
+ *
+ * \param[in] collection Collection of entities corresponding to the current wait set.
+ * \param[in] wait_result Result of rclcpp::WaitSet::wait corresponding to the collection.
+ * \param[inout] queue of executables to append new ready executables to
+ * \return number of new ready executables
+ */
+size_t
+ready_executables(
+  const ExecutorEntitiesCollection & collection,
+  rclcpp::WaitResult<rclcpp::WaitSet> & wait_result,
+  std::deque<rclcpp::AnyExecutable> & executables
+);
+}  // namespace executors
+}  // namespace rclcpp
+
+#endif  // RCLCPP__EXECUTORS__EXECUTOR_ENTITIES_COLLECTION_HPP_

rclcpp/include/rclcpp/executors/executor_entities_collector.hpp

@@ -0,0 +1,270 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__EXECUTORS__EXECUTOR_ENTITIES_COLLECTOR_HPP_
+#define RCLCPP__EXECUTORS__EXECUTOR_ENTITIES_COLLECTOR_HPP_
+
+#include <map>
+#include <memory>
+#include <mutex>
+#include <set>
+#include <vector>
+
+#include "rcpputils/thread_safety_annotations.hpp"
+
+#include <rclcpp/any_executable.hpp>
+#include <rclcpp/node_interfaces/node_base.hpp>
+#include <rclcpp/callback_group.hpp>
+#include <rclcpp/executors/executor_notify_waitable.hpp>
+#include <rclcpp/visibility_control.hpp>
+#include <rclcpp/wait_set.hpp>
+#include <rclcpp/wait_result.hpp>
+
+namespace rclcpp
+{
+namespace executors
+{
+
+/// Class to monitor a set of nodes and callback groups for changes in entity membership
+/**
+ * This is to be used with an executor to track the membership of various nodes, groups,
+ * and entities (timers, subscriptions, clients, services, etc) and report status to the
+ * executor.
+ *
+ * In general, users will add either nodes or callback groups to an executor.
+ * Each node may have callback groups that are automatically associated with executors,
+ * or callback groups that must be manually associated with an executor.
+ *
+ * This object tracks both types of callback groups as well as nodes that have been
+ * previously added to the executor.
+ * When a new callback group is added/removed or new entities are added/removed, the
+ * corresponding node or callback group will signal this to the executor so that the
+ * entity collection may be rebuilt according to that executor's implementation.
+ *
+ */
+class ExecutorEntitiesCollector
+{
+public:
+  /// Constructor
+  /**
+   * \param[in] notify_waitable Waitable that is used to signal to the executor
+   *   when nodes or callback groups have been added or removed.
+   */
+  RCLCPP_PUBLIC
+  explicit ExecutorEntitiesCollector(
+    std::shared_ptr<ExecutorNotifyWaitable> notify_waitable);
+
+  /// Destructor
+  RCLCPP_PUBLIC
+  ~ExecutorEntitiesCollector();
+
+  /// Indicate if the entities collector has pending additions or removals.
+  /**
+   * \return true if there are pending additions or removals
+   */
+  bool has_pending() const;
+
+  /// Add a node to the entity collector
+  /**
+   * \param[in] node_ptr a shared pointer that points to a node base interface
+   * \throw std::runtime_error if the node is associated with an executor
+   */
+  RCLCPP_PUBLIC
+  void
+  add_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr);
+
+  /// Remove a node from the entity collector
+  /**
+   * \param[in] node_ptr a shared pointer that points to a node base interface
+   * \throw std::runtime_error if the node is associated with an executor
+   * \throw std::runtime_error if the node is associated with this executor
+   */
+  RCLCPP_PUBLIC
+  void
+  remove_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr);
+
+  /// Add a callback group to the entity collector
+  /**
+   * \param[in] group_ptr a shared pointer that points to a callback group
+   * \throw std::runtime_error if the callback_group is associated with an executor
+   */
+  RCLCPP_PUBLIC
+  void
+  add_callback_group(rclcpp::CallbackGroup::SharedPtr group_ptr);
+
+  /// Remove a callback group from the entity collector
+  /**
+   * \param[in] group_ptr a shared pointer that points to a callback group
+   * \throw std::runtime_error if the callback_group is not associated with an executor
+   * \throw std::runtime_error if the callback_group is not associated with this executor
+   */
+  RCLCPP_PUBLIC
+  void
+  remove_callback_group(rclcpp::CallbackGroup::SharedPtr group_ptr);
+
+  /// Get all callback groups known to this entity collector
+  /**
+   * This will include manually added and automatically added (node associated) groups
+   * \return vector of all callback groups
+   */
+  RCLCPP_PUBLIC
+  std::vector<rclcpp::CallbackGroup::WeakPtr>
+  get_all_callback_groups() const;
+
+  /// Get manually-added callback groups known to this entity collector
+  /**
+   * This will include callback groups that have been added via add_callback_group
+   * \return vector of manually-added callback groups
+   */
+  RCLCPP_PUBLIC
+  std::vector<rclcpp::CallbackGroup::WeakPtr>
+  get_manually_added_callback_groups() const;
+
+  /// Get automatically-added callback groups known to this entity collector
+  /**
+   * This will include callback groups that are associated with nodes added via add_node
+   * \return vector of automatically-added callback groups
+   */
+  RCLCPP_PUBLIC
+  std::vector<rclcpp::CallbackGroup::WeakPtr>
+  get_automatically_added_callback_groups() const;
+
+  /// Update the underlying collections
+  /**
+   * This will prune nodes and callback groups that are no longer valid as well
+   * as add new callback groups from any associated nodes.
+   */
+  RCLCPP_PUBLIC
+  void
+  update_collections();
+
+protected:
+  using NodeCollection = std::set<
+    rclcpp::node_interfaces::NodeBaseInterface::WeakPtr,
+    std::owner_less<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr>>;
+
+  using CallbackGroupCollection = std::set<
+    rclcpp::CallbackGroup::WeakPtr,
+    std::owner_less<rclcpp::CallbackGroup::WeakPtr>>;
+
+  using WeakNodesToGuardConditionsMap = std::map<
+    rclcpp::node_interfaces::NodeBaseInterface::WeakPtr,
+    rclcpp::GuardCondition::WeakPtr,
+    std::owner_less<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr>>;
+
+  using WeakGroupsToGuardConditionsMap = std::map<
+    rclcpp::CallbackGroup::WeakPtr,
+    rclcpp::GuardCondition::WeakPtr,
+    std::owner_less<rclcpp::CallbackGroup::WeakPtr>>;
+
+  /// Implementation of removing a node from the collector.
+  /**
+   * This will disassociate the node from the collector and remove any
+   * automatically-added callback groups
+   *
+   * This takes and returns an iterator so it may be used as:
+   *
+   * it = remove_weak_node(it);
+   *
+   * \param[in] weak_node iterator to the weak node to be removed
+   * \return Valid updated iterator in the same collection
+   */
+  RCLCPP_PUBLIC
+  NodeCollection::iterator
+  remove_weak_node(NodeCollection::iterator weak_node) RCPPUTILS_TSA_REQUIRES(mutex_);
+
+  /// Implementation of removing a callback group from the collector.
+  /**
+   * This will disassociate the callback group from the collector
+   *
+   * This takes and returns an iterator so it may be used as:
+   *
+   * it = remove_weak_callback_group(it);
+   *
+   * \param[in] weak_group_it iterator to the weak group to be removed
+   * \param[in] collection the collection to remove the group from
+   *   (manually or automatically added)
+   * \return Valid updated iterator in the same collection
+   */
+  RCLCPP_PUBLIC
+  CallbackGroupCollection::iterator
+  remove_weak_callback_group(
+    CallbackGroupCollection::iterator weak_group_it,
+    CallbackGroupCollection & collection) RCPPUTILS_TSA_REQUIRES(mutex_);
+
+  /// Implementation of adding a callback group
+  /**
+   * \param[in] group_ptr the group to add
+   * \param[in] collection the collection to add the group to
+   */
+  RCLCPP_PUBLIC
+  void
+  add_callback_group_to_collection(
+    rclcpp::CallbackGroup::SharedPtr group_ptr,
+    CallbackGroupCollection & collection)  RCPPUTILS_TSA_REQUIRES(mutex_);
+
+  /// Iterate over queued added/remove nodes and callback_groups
+  RCLCPP_PUBLIC
+  void
+  process_queues() RCPPUTILS_TSA_REQUIRES(mutex_);
+
+  /// Check a collection of nodes and add any new callback_groups that
+  /// are set to be automatically associated via the node.
+  RCLCPP_PUBLIC
+  void
+  add_automatically_associated_callback_groups(
+    const NodeCollection & nodes_to_check) RCPPUTILS_TSA_REQUIRES(mutex_);
+
+  /// Check all nodes and group for expired weak pointers and remove them.
+  RCLCPP_PUBLIC
+  void
+  prune_invalid_nodes_and_groups() RCPPUTILS_TSA_REQUIRES(mutex_);
+
+  /// mutex to protect collections and pending queues
+  mutable std::mutex mutex_;
+
+  /// Callback groups that were added via `add_callback_group`
+  CallbackGroupCollection manually_added_groups_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+
+  /// Callback groups that were added by their association with added nodes
+  CallbackGroupCollection automatically_added_groups_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+
+  /// nodes that are associated with the executor
+  NodeCollection weak_nodes_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+
+  /// Track guard conditions associated with added nodes
+  WeakNodesToGuardConditionsMap weak_nodes_to_guard_conditions_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+
+  /// Track guard conditions associated with added callback groups
+  WeakGroupsToGuardConditionsMap weak_groups_to_guard_conditions_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+
+  /// nodes that have been added since the last update.
+  NodeCollection pending_added_nodes_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+
+  /// nodes that have been removed since the last update.
+  NodeCollection pending_removed_nodes_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+
+  /// callback groups that have been added since the last update.
+  CallbackGroupCollection pending_manually_added_groups_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+
+  /// callback groups that have been removed since the last update.
+  CallbackGroupCollection pending_manually_removed_groups_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+
+  /// Waitable to add guard conditions to
+  std::shared_ptr<ExecutorNotifyWaitable> notify_waitable_;
+};
+}  // namespace executors
+}  // namespace rclcpp
+//
+#endif  // RCLCPP__EXECUTORS__EXECUTOR_ENTITIES_COLLECTOR_HPP_

rclcpp/include/rclcpp/executors/executor_notify_waitable.hpp

@@ -0,0 +1,158 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__EXECUTORS__EXECUTOR_NOTIFY_WAITABLE_HPP_
+#define RCLCPP__EXECUTORS__EXECUTOR_NOTIFY_WAITABLE_HPP_
+
+#include <functional>
+#include <memory>
+#include <mutex>
+#include <set>
+
+#include "rclcpp/guard_condition.hpp"
+#include "rclcpp/waitable.hpp"
+
+namespace rclcpp
+{
+namespace executors
+{
+
+/// Maintain a collection of guard conditions from associated nodes and callback groups
+/// to signal to the executor when associated entities have changed.
+class ExecutorNotifyWaitable : public rclcpp::Waitable
+{
+public:
+  RCLCPP_SMART_PTR_DEFINITIONS(ExecutorNotifyWaitable)
+
+  // Constructor
+  /**
+   * \param[in] on_execute_callback Callback to execute when one of the conditions
+   *   of this waitable has signaled the wait_set.
+   */
+  RCLCPP_PUBLIC
+  explicit ExecutorNotifyWaitable(std::function<void(void)> on_execute_callback = {});
+
+  // Destructor
+  RCLCPP_PUBLIC
+  ~ExecutorNotifyWaitable() override = default;
+
+  RCLCPP_PUBLIC
+  ExecutorNotifyWaitable(const ExecutorNotifyWaitable & other);
+
+
+  RCLCPP_PUBLIC
+  ExecutorNotifyWaitable & operator=(const ExecutorNotifyWaitable & other);
+
+  /// Add conditions to the wait set
+  /**
+   * \param[inout] wait_set structure that conditions will be added to
+   */
+  RCLCPP_PUBLIC
+  void
+  add_to_wait_set(rcl_wait_set_t * wait_set) override;
+
+  /// Check conditions against the wait set
+  /**
+   * \param[inout] wait_set structure that internal elements will be checked against.
+   * \return true if this waitable is ready to be executed, false otherwise.
+   */
+  RCLCPP_PUBLIC
+  bool
+  is_ready(rcl_wait_set_t * wait_set) override;
+
+  /// Perform work associated with the waitable.
+  /**
+   * This will call the callback provided in the constructor.
+   * \param[in] data Data to be use for the execute, if available, else nullptr.
+   */
+  RCLCPP_PUBLIC
+  void
+  execute(std::shared_ptr<void> & data) override;
+
+  /// Retrieve data to be used in the next execute call.
+  /**
+   * \return If available, data to be used, otherwise nullptr
+   */
+  RCLCPP_PUBLIC
+  std::shared_ptr<void>
+  take_data() override;
+
+  /// Take the data from an entity ID so that it can be consumed with `execute`.
+  /**
+   * \param[in] id ID of the entity to take data from.
+   * \return If available, data to be used, otherwise nullptr
+   * \sa rclcpp::Waitable::take_data_by_entity_id
+   */
+  RCLCPP_PUBLIC
+  std::shared_ptr<void>
+  take_data_by_entity_id(size_t id) override;
+
+  /// Set a callback to be called whenever the waitable becomes ready.
+  /**
+   * \param[in] callback callback to set
+   * \sa rclcpp::Waitable::set_on_ready_callback
+   */
+  RCLCPP_PUBLIC
+  void
+  set_on_ready_callback(std::function<void(size_t, int)> callback) override;
+
+  /// Add a guard condition to be waited on.
+  /**
+   * \param[in] guard_condition The guard condition to add.
+   */
+  RCLCPP_PUBLIC
+  void
+  add_guard_condition(rclcpp::GuardCondition::WeakPtr guard_condition);
+
+  /// Unset any callback registered via set_on_ready_callback.
+  /**
+   * \sa rclcpp::Waitable::clear_on_ready_callback
+   */
+  RCLCPP_PUBLIC
+  void
+  clear_on_ready_callback() override;
+
+  /// Remove a guard condition from being waited on.
+  /**
+   * \param[in] weak_guard_condition The guard condition to remove.
+   */
+  RCLCPP_PUBLIC
+  void
+  remove_guard_condition(rclcpp::GuardCondition::WeakPtr weak_guard_condition);
+
+  /// Get the number of ready guard_conditions
+  /**
+   * \return The number of guard_conditions associated with the Waitable.
+   */
+  RCLCPP_PUBLIC
+  size_t
+  get_number_of_ready_guard_conditions() override;
+
+private:
+  /// Callback to run when waitable executes
+  std::function<void(void)> execute_callback_;
+
+  std::mutex guard_condition_mutex_;
+
+  std::function<void(size_t)> on_ready_callback_;
+
+  /// The collection of guard conditions to be waited on.
+  std::set<rclcpp::GuardCondition::WeakPtr,
+    std::owner_less<rclcpp::GuardCondition::WeakPtr>> notify_guard_conditions_;
+};
+
+}  // namespace executors
+}  // namespace rclcpp
+
+#endif  // RCLCPP__EXECUTORS__EXECUTOR_NOTIFY_WAITABLE_HPP_

rclcpp/include/rclcpp/executors/static_executor_entities_collector.hpp

@@ -1,357 +0,0 @@
-// Copyright 2020 Open Source Robotics Foundation, Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#ifndef RCLCPP__EXECUTORS__STATIC_EXECUTOR_ENTITIES_COLLECTOR_HPP_
-#define RCLCPP__EXECUTORS__STATIC_EXECUTOR_ENTITIES_COLLECTOR_HPP_
-
-#include <chrono>
-#include <list>
-#include <map>
-#include <memory>
-#include <vector>
-
-#include "rcl/guard_condition.h"
-#include "rcl/wait.h"
-
-#include "rclcpp/experimental/executable_list.hpp"
-#include "rclcpp/macros.hpp"
-#include "rclcpp/memory_strategy.hpp"
-#include "rclcpp/visibility_control.hpp"
-#include "rclcpp/waitable.hpp"
-
-namespace rclcpp
-{
-namespace executors
-{
-typedef std::map<rclcpp::CallbackGroup::WeakPtr,
-    rclcpp::node_interfaces::NodeBaseInterface::WeakPtr,
-    std::owner_less<rclcpp::CallbackGroup::WeakPtr>> WeakCallbackGroupsToNodesMap;
-
-class StaticExecutorEntitiesCollector final
-  : public rclcpp::Waitable,
-  public std::enable_shared_from_this<StaticExecutorEntitiesCollector>
-{
-public:
-  RCLCPP_SMART_PTR_DEFINITIONS(StaticExecutorEntitiesCollector)
-
-  // Constructor
-  RCLCPP_PUBLIC
-  StaticExecutorEntitiesCollector() = default;
-
-  // Destructor
-  RCLCPP_PUBLIC
-  ~StaticExecutorEntitiesCollector();
-
-  /// Initialize StaticExecutorEntitiesCollector
-  /**
-   * \param p_wait_set A reference to the wait set to be used in the executor
-   * \param memory_strategy Shared pointer to the memory strategy to set.
-   * \throws std::runtime_error if memory strategy is null
-   */
-  RCLCPP_PUBLIC
-  void
-  init(
-    rcl_wait_set_t * p_wait_set,
-    rclcpp::memory_strategy::MemoryStrategy::SharedPtr memory_strategy);
-
-  /// Finalize StaticExecutorEntitiesCollector to clear resources
-  RCLCPP_PUBLIC
-  bool
-  is_init() {return initialized_;}
-
-  RCLCPP_PUBLIC
-  void
-  fini();
-
-  /// Execute the waitable.
-  RCLCPP_PUBLIC
-  void
-  execute(std::shared_ptr<void> & data) override;
-
-  /// Take the data so that it can be consumed with `execute`.
-  /**
-   * For `StaticExecutorEntitiesCollector`, this always return `nullptr`.
-   * \sa rclcpp::Waitable::take_data()
-   */
-  RCLCPP_PUBLIC
-  std::shared_ptr<void>
-  take_data() override;
-
-  /// Function to add_handles_to_wait_set and wait for work and
-  /**
-   * block until the wait set is ready or until the timeout has been exceeded.
-   * \throws std::runtime_error if wait set couldn't be cleared or filled.
-   * \throws any rcl errors from rcl_wait, \see rclcpp::exceptions::throw_from_rcl_error()
-   */
-  RCLCPP_PUBLIC
-  void
-  refresh_wait_set(std::chrono::nanoseconds timeout = std::chrono::nanoseconds(-1));
-
-  /**
-   * \throws std::runtime_error if it couldn't add guard condition to wait set
-   */
-  RCLCPP_PUBLIC
-  void
-  add_to_wait_set(rcl_wait_set_t * wait_set) override;
-
-  RCLCPP_PUBLIC
-  size_t
-  get_number_of_ready_guard_conditions() override;
-
-  /// Add a callback group to an executor.
-  /**
-   * \see rclcpp::Executor::add_callback_group
-   */
-  RCLCPP_PUBLIC
-  bool
-  add_callback_group(
-    rclcpp::CallbackGroup::SharedPtr group_ptr,
-    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr);
-
-  /// Add a callback group to an executor.
-  /**
-   * \see rclcpp::Executor::add_callback_group
-   * \return boolean whether the node from the callback group is new
-   */
-  RCLCPP_PUBLIC
-  bool
-  add_callback_group(
-    rclcpp::CallbackGroup::SharedPtr group_ptr,
-    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-    WeakCallbackGroupsToNodesMap & weak_groups_to_nodes);
-
-  /// Remove a callback group from the executor.
-  /**
-   * \see rclcpp::Executor::remove_callback_group
-   */
-  RCLCPP_PUBLIC
-  bool
-  remove_callback_group(
-    rclcpp::CallbackGroup::SharedPtr group_ptr);
-
-  /// Remove a callback group from the executor.
-  /**
-   * \see rclcpp::Executor::remove_callback_group_from_map
-   */
-  RCLCPP_PUBLIC
-  bool
-  remove_callback_group_from_map(
-    rclcpp::CallbackGroup::SharedPtr group_ptr,
-    WeakCallbackGroupsToNodesMap & weak_groups_to_nodes);
-
-  /**
-   * \see rclcpp::Executor::add_node()
-   * \throw std::runtime_error if node was already added
-   */
-  RCLCPP_PUBLIC
-  bool
-  add_node(
-    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr);
-
-  /**
-   * \see rclcpp::Executor::remove_node()
-   * \throw std::runtime_error if no guard condition is associated with node.
-   */
-  RCLCPP_PUBLIC
-  bool
-  remove_node(
-    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr);
-
-  RCLCPP_PUBLIC
-  std::vector<rclcpp::CallbackGroup::WeakPtr>
-  get_all_callback_groups();
-
-  /// Get callback groups that belong to executor.
-  /**
-   * \see rclcpp::Executor::get_manually_added_callback_groups()
-   */
-  RCLCPP_PUBLIC
-  std::vector<rclcpp::CallbackGroup::WeakPtr>
-  get_manually_added_callback_groups();
-
-  /// Get callback groups that belong to executor.
-  /**
-   * \see rclcpp::Executor::get_automatically_added_callback_groups_from_nodes()
-   */
-  RCLCPP_PUBLIC
-  std::vector<rclcpp::CallbackGroup::WeakPtr>
-  get_automatically_added_callback_groups_from_nodes();
-
-  /// Complete all available queued work without blocking.
-  /**
-   * This function checks if after the guard condition was triggered
-   * (or a spurious wakeup happened) we are really ready to execute
-   * i.e. re-collect entities
-   */
-  RCLCPP_PUBLIC
-  bool
-  is_ready(rcl_wait_set_t * wait_set) override;
-
-  /// Return number of timers
-  /**
-   * \return number of timers
-   */
-  RCLCPP_PUBLIC
-  size_t
-  get_number_of_timers() {return exec_list_.number_of_timers;}
-
-  /// Return number of subscriptions
-  /**
-   * \return number of subscriptions
-   */
-  RCLCPP_PUBLIC
-  size_t
-  get_number_of_subscriptions() {return exec_list_.number_of_subscriptions;}
-
-  /// Return number of services
-  /**
-   * \return number of services
-   */
-  RCLCPP_PUBLIC
-  size_t
-  get_number_of_services() {return exec_list_.number_of_services;}
-
-  /// Return number of clients
-  /**
-   * \return number of clients
-   */
-  RCLCPP_PUBLIC
-  size_t
-  get_number_of_clients() {return exec_list_.number_of_clients;}
-
-  /// Return number of waitables
-  /**
-   * \return number of waitables
-   */
-  RCLCPP_PUBLIC
-  size_t
-  get_number_of_waitables() {return exec_list_.number_of_waitables;}
-
-  /** Return a SubscritionBase Sharedptr by index.
-   * \param[in] i The index of the SubscritionBase
-   * \return a SubscritionBase shared pointer
-   * \throws std::out_of_range if the argument is higher than the size of the structrue.
-   */
-  RCLCPP_PUBLIC
-  rclcpp::SubscriptionBase::SharedPtr
-  get_subscription(size_t i) {return exec_list_.subscription[i];}
-
-  /** Return a TimerBase Sharedptr by index.
-   * \param[in] i The index of the TimerBase
-   * \return a TimerBase shared pointer
-   * \throws std::out_of_range if the argument is higher than the size.
-   */
-  RCLCPP_PUBLIC
-  rclcpp::TimerBase::SharedPtr
-  get_timer(size_t i) {return exec_list_.timer[i];}
-
-  /** Return a ServiceBase Sharedptr by index.
-   * \param[in] i The index of the ServiceBase
-   * \return a ServiceBase shared pointer
-   * \throws std::out_of_range if the argument is higher than the size.
-   */
-  RCLCPP_PUBLIC
-  rclcpp::ServiceBase::SharedPtr
-  get_service(size_t i) {return exec_list_.service[i];}
-
-  /** Return a ClientBase Sharedptr by index
-   * \param[in] i The index of the ClientBase
-   * \return a ClientBase shared pointer
-   * \throws std::out_of_range if the argument is higher than the size.
-   */
-  RCLCPP_PUBLIC
-  rclcpp::ClientBase::SharedPtr
-  get_client(size_t i) {return exec_list_.client[i];}
-
-  /** Return a Waitable Sharedptr by index
-   * \param[in] i The index of the Waitable
-   * \return a Waitable shared pointer
-   * \throws std::out_of_range if the argument is higher than the size.
-   */
-  RCLCPP_PUBLIC
-  rclcpp::Waitable::SharedPtr
-  get_waitable(size_t i) {return exec_list_.waitable[i];}
-
-private:
-  /// Function to reallocate space for entities in the wait set.
-  /**
-   * \throws std::runtime_error if wait set couldn't be cleared or resized.
-   */
-  void
-  prepare_wait_set();
-
-  void
-  fill_executable_list();
-
-  void
-  fill_memory_strategy();
-
-  /// Return true if the node belongs to the collector
-  /**
-   * \param[in] node_ptr a node base interface shared pointer
-   * \param[in] weak_groups_to_nodes map to nodes to lookup
-   * \return boolean whether a node belongs the collector
-   */
-  bool
-  has_node(
-    const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-    const WeakCallbackGroupsToNodesMap & weak_groups_to_nodes) const;
-
-  /// Add all callback groups that can be automatically added by any executor
-  /// and is not already associated with an executor from nodes
-  /// that are associated with executor
-  /**
-   * \see rclcpp::Executor::add_callback_groups_from_nodes_associated_to_executor()
-   */
-  void
-  add_callback_groups_from_nodes_associated_to_executor();
-
-  void
-  fill_executable_list_from_map(const WeakCallbackGroupsToNodesMap & weak_groups_to_nodes);
-
-  /// Memory strategy: an interface for handling user-defined memory allocation strategies.
-  rclcpp::memory_strategy::MemoryStrategy::SharedPtr memory_strategy_;
-
-  // maps callback groups to nodes.
-  WeakCallbackGroupsToNodesMap weak_groups_associated_with_executor_to_nodes_;
-  // maps callback groups to nodes.
-  WeakCallbackGroupsToNodesMap weak_groups_to_nodes_associated_with_executor_;
-
-  typedef std::map<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr,
-      const rclcpp::GuardCondition *,
-      std::owner_less<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr>>
-    WeakNodesToGuardConditionsMap;
-  WeakNodesToGuardConditionsMap weak_nodes_to_guard_conditions_;
-
-  /// List of weak nodes registered in the static executor
-  std::list<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr> weak_nodes_;
-
-  // Mutex to protect vector of new nodes.
-  std::mutex new_nodes_mutex_;
-  std::vector<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr> new_nodes_;
-
-  /// Wait set for managing entities that the rmw layer waits on.
-  rcl_wait_set_t * p_wait_set_ = nullptr;
-
-  /// Executable list: timers, subscribers, clients, services and waitables
-  rclcpp::experimental::ExecutableList exec_list_;
-
-  /// Bool to check if the entities collector has been initialized
-  bool initialized_ = false;
-};
-
-}  // namespace executors
-}  // namespace rclcpp
-
-#endif  // RCLCPP__EXECUTORS__STATIC_EXECUTOR_ENTITIES_COLLECTOR_HPP_

rclcpp/include/rclcpp/executors/static_single_threaded_executor.hpp

@@ -15,24 +15,13 @@
 #ifndef RCLCPP__EXECUTORS__STATIC_SINGLE_THREADED_EXECUTOR_HPP_
 #define RCLCPP__EXECUTORS__STATIC_SINGLE_THREADED_EXECUTOR_HPP_
 
+#include <atomic>
 #include <chrono>
-#include <cassert>
-#include <cstdlib>
 #include <memory>
-#include <vector>
-#include <string>
-
-#include "rmw/rmw.h"
 
 #include "rclcpp/executor.hpp"
-#include "rclcpp/executors/static_executor_entities_collector.hpp"
-#include "rclcpp/experimental/executable_list.hpp"
-#include "rclcpp/macros.hpp"
-#include "rclcpp/memory_strategies.hpp"
-#include "rclcpp/node.hpp"
-#include "rclcpp/rate.hpp"
-#include "rclcpp/utilities.hpp"
-#include "rclcpp/visibility_control.hpp"
+#include "rclcpp/executors/executor_entities_collection.hpp"
+#include "rclcpp/executors/single_threaded_executor.hpp"
 
 namespace rclcpp
 {
@@ -65,7 +54,7 @@ public:
   explicit StaticSingleThreadedExecutor(
     const rclcpp::ExecutorOptions & options = rclcpp::ExecutorOptions());
 
-  /// Default destrcutor.
+  /// Default destructor.
   RCLCPP_PUBLIC
   virtual ~StaticSingleThreadedExecutor();
 
@@ -116,92 +105,20 @@ public:
   void
   spin_all(std::chrono::nanoseconds max_duration) override;
 
-  /// Add a callback group to an executor.
-  /**
-   * \sa rclcpp::Executor::add_callback_group
-   */
-  RCLCPP_PUBLIC
-  void
-  add_callback_group(
-    rclcpp::CallbackGroup::SharedPtr group_ptr,
-    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-    bool notify = true) override;
-
-  /// Remove callback group from the executor
-  /**
-   * \sa rclcpp::Executor::remove_callback_group
-   */
-  RCLCPP_PUBLIC
-  void
-  remove_callback_group(
-    rclcpp::CallbackGroup::SharedPtr group_ptr,
-    bool notify = true) override;
-
-  /// Add a node to the executor.
-  /**
-   * \sa rclcpp::Executor::add_node
-   */
-  RCLCPP_PUBLIC
-  void
-  add_node(
-    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-    bool notify = true) override;
-
-  /// Convenience function which takes Node and forwards NodeBaseInterface.
-  /**
-   * \sa rclcpp::StaticSingleThreadedExecutor::add_node
-   */
-  RCLCPP_PUBLIC
-  void
-  add_node(std::shared_ptr<rclcpp::Node> node_ptr, bool notify = true) override;
-
-  /// Remove a node from the executor.
-  /**
-   * \sa rclcpp::Executor::remove_node
-   */
-  RCLCPP_PUBLIC
-  void
-  remove_node(
-    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-    bool notify = true) override;
-
-  /// Convenience function which takes Node and forwards NodeBaseInterface.
-  /**
-   * \sa rclcpp::Executor::remove_node
-   */
-  RCLCPP_PUBLIC
-  void
-  remove_node(std::shared_ptr<rclcpp::Node> node_ptr, bool notify = true) override;
-
-  RCLCPP_PUBLIC
-  std::vector<rclcpp::CallbackGroup::WeakPtr>
-  get_all_callback_groups() override;
-
-  /// Get callback groups that belong to executor.
-  /**
-   * \sa rclcpp::Executor::get_manually_added_callback_groups()
-   */
-  RCLCPP_PUBLIC
-  std::vector<rclcpp::CallbackGroup::WeakPtr>
-  get_manually_added_callback_groups() override;
-
-  /// Get callback groups that belong to executor.
-  /**
-   * \sa rclcpp::Executor::get_automatically_added_callback_groups_from_nodes()
-   */
-  RCLCPP_PUBLIC
-  std::vector<rclcpp::CallbackGroup::WeakPtr>
-  get_automatically_added_callback_groups_from_nodes() override;
-
 protected:
   /**
    * @brief Executes ready executables from wait set.
+   * @param collection entities to evaluate for ready executables.
+   * @param wait_result result to check for ready executables.
    * @param spin_once if true executes only the first ready executable.
    * @return true if any executable was ready.
    */
   RCLCPP_PUBLIC
   bool
-  execute_ready_executables(bool spin_once = false);
+  execute_ready_executables(
+    const rclcpp::executors::ExecutorEntitiesCollection & collection,
+    rclcpp::WaitResult<rclcpp::WaitSet> & wait_result,
+    bool spin_once);
 
   RCLCPP_PUBLIC
   void
@@ -213,8 +130,6 @@ protected:
 
 private:
   RCLCPP_DISABLE_COPY(StaticSingleThreadedExecutor)
-
-  StaticExecutorEntitiesCollector::SharedPtr entities_collector_;
 };
 
 }  // namespace executors

rclcpp/include/rclcpp/experimental/buffers/intra_process_buffer.hpp

@@ -24,6 +24,7 @@
 #include "rclcpp/allocator/allocator_deleter.hpp"
 #include "rclcpp/experimental/buffers/buffer_implementation_base.hpp"
 #include "rclcpp/macros.hpp"
+#include "tracetools/tracetools.h"
 
 namespace rclcpp
 {
@@ -94,6 +95,10 @@ public:
 
     buffer_ = std::move(buffer_impl);
 
+    TRACEPOINT(
+      rclcpp_buffer_to_ipb,
+      static_cast<const void *>(buffer_.get()),
+      static_cast<const void *>(this));
     if (!allocator) {
       message_allocator_ = std::make_shared<MessageAlloc>();
     } else {

rclcpp/include/rclcpp/experimental/buffers/ring_buffer_implementation.hpp

@@ -25,6 +25,7 @@
 #include "rclcpp/logging.hpp"
 #include "rclcpp/macros.hpp"
 #include "rclcpp/visibility_control.hpp"
+#include "tracetools/tracetools.h"
 
 namespace rclcpp
 {
@@ -51,6 +52,7 @@ public:
     if (capacity == 0) {
       throw std::invalid_argument("capacity must be a positive, non-zero value");
     }
+    TRACEPOINT(rclcpp_construct_ring_buffer, static_cast<const void *>(this), capacity_);
   }
 
   virtual ~RingBufferImplementation() {}
@@ -67,6 +69,12 @@ public:
 
     write_index_ = next_(write_index_);
     ring_buffer_[write_index_] = std::move(request);
+    TRACEPOINT(
+      rclcpp_ring_buffer_enqueue,
+      static_cast<const void *>(this),
+      write_index_,
+      size_ + 1,
+      is_full_());
 
     if (is_full_()) {
       read_index_ = next_(read_index_);
@@ -90,6 +98,11 @@ public:
     }
 
     auto request = std::move(ring_buffer_[read_index_]);
+    TRACEPOINT(
+      rclcpp_ring_buffer_dequeue,
+      static_cast<const void *>(this),
+      read_index_,
+      size_ - 1);
     read_index_ = next_(read_index_);
 
     size_--;
@@ -135,7 +148,10 @@ public:
     return is_full_();
   }
 
-  void clear() {}
+  void clear()
+  {
+    TRACEPOINT(rclcpp_ring_buffer_clear, static_cast<const void *>(this));
+  }
 
 private:
   /// Get the next index value for the ring buffer

rclcpp/include/rclcpp/experimental/executors/events_executor/events_executor.hpp

@@ -0,0 +1,286 @@
+// Copyright 2023 iRobot Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__EVENTS_EXECUTOR_HPP_
+#define RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__EVENTS_EXECUTOR_HPP_
+
+#include <atomic>
+#include <chrono>
+#include <memory>
+#include <vector>
+
+#include "rclcpp/executor.hpp"
+#include "rclcpp/executors/executor_entities_collection.hpp"
+#include "rclcpp/executors/executor_entities_collector.hpp"
+#include "rclcpp/experimental/executors/events_executor/events_executor_event_types.hpp"
+#include "rclcpp/experimental/executors/events_executor/events_queue.hpp"
+#include "rclcpp/experimental/executors/events_executor/simple_events_queue.hpp"
+#include "rclcpp/experimental/timers_manager.hpp"
+#include "rclcpp/node.hpp"
+
+namespace rclcpp
+{
+namespace experimental
+{
+namespace executors
+{
+
+/// Events executor implementation
+/**
+ * This executor uses an events queue and a timers manager to execute entities from its
+ * associated nodes and callback groups.
+ * ROS 2 entities allow to set callback functions that are invoked when the entity is triggered
+ * or has work to do. The events-executor sets these callbacks such that they push an
+ * event into its queue.
+ *
+ * This executor tries to reduce as much as possible the amount of maintenance operations.
+ * This allows to use customized `EventsQueue` classes to achieve different goals such
+ * as very low CPU usage, bounded memory requirement, determinism, etc.
+ *
+ * The executor uses a weak ownership model and it locks entities only while executing
+ * their related events.
+ *
+ * To run this executor:
+ * rclcpp::experimental::executors::EventsExecutor executor;
+ * executor.add_node(node);
+ * executor.spin();
+ * executor.remove_node(node);
+ */
+class EventsExecutor : public rclcpp::Executor
+{
+  friend class EventsExecutorEntitiesCollector;
+
+public:
+  RCLCPP_SMART_PTR_DEFINITIONS(EventsExecutor)
+
+  /// Default constructor. See the default constructor for Executor.
+  /**
+   * \param[in] events_queue The queue used to store events.
+   * \param[in] execute_timers_separate_thread If true, timers are executed in a separate
+   * thread. If false, timers are executed in the same thread as all other entities.
+   * \param[in] options Options used to configure the executor.
+   */
+  RCLCPP_PUBLIC
+  explicit EventsExecutor(
+    rclcpp::experimental::executors::EventsQueue::UniquePtr events_queue = std::make_unique<
+      rclcpp::experimental::executors::SimpleEventsQueue>(),
+    bool execute_timers_separate_thread = false,
+    const rclcpp::ExecutorOptions & options = rclcpp::ExecutorOptions());
+
+  /// Default destructor.
+  RCLCPP_PUBLIC
+  virtual ~EventsExecutor();
+
+  /// Events executor implementation of spin.
+  /**
+   * This function will block until work comes in, execute it, and keep blocking.
+   * It will only be interrupted by a CTRL-C (managed by the global signal handler).
+   * \throws std::runtime_error when spin() called while already spinning
+   */
+  RCLCPP_PUBLIC
+  void
+  spin() override;
+
+  /// Events executor implementation of spin some
+  /**
+   * This non-blocking function will execute the timers and events
+   * that were ready when this API was called, until timeout or no
+   * more work available. New ready-timers/events arrived while
+   * executing work, won't be taken into account here.
+   *
+   * Example:
+   *   while(condition) {
+   *     spin_some();
+   *     sleep(); // User should have some sync work or
+   *              // sleep to avoid a 100% CPU usage
+   *   }
+   */
+  RCLCPP_PUBLIC
+  void
+  spin_some(std::chrono::nanoseconds max_duration = std::chrono::nanoseconds(0)) override;
+
+  /// Events executor implementation of spin all
+  /**
+   * This non-blocking function will execute timers and events
+   * until timeout or no more work available. If new ready-timers/events
+   * arrive while executing work available, they will be executed
+   * as long as the timeout hasn't expired.
+   *
+   * Example:
+   *   while(condition) {
+   *     spin_all();
+   *     sleep(); // User should have some sync work or
+   *              // sleep to avoid a 100% CPU usage
+   *   }
+   */
+  RCLCPP_PUBLIC
+  void
+  spin_all(std::chrono::nanoseconds max_duration) override;
+
+  /// Add a node to the executor.
+  /**
+   * \sa rclcpp::Executor::add_node
+   */
+  RCLCPP_PUBLIC
+  void
+  add_node(
+    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
+    bool notify = true) override;
+
+  /// Convenience function which takes Node and forwards NodeBaseInterface.
+  /**
+   * \sa rclcpp::EventsExecutor::add_node
+   */
+  RCLCPP_PUBLIC
+  void
+  add_node(std::shared_ptr<rclcpp::Node> node_ptr, bool notify = true) override;
+
+  /// Remove a node from the executor.
+  /**
+   * \sa rclcpp::Executor::remove_node
+   */
+  RCLCPP_PUBLIC
+  void
+  remove_node(
+    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
+    bool notify = true) override;
+
+  /// Convenience function which takes Node and forwards NodeBaseInterface.
+  /**
+   * \sa rclcpp::Executor::remove_node
+   */
+  RCLCPP_PUBLIC
+  void
+  remove_node(std::shared_ptr<rclcpp::Node> node_ptr, bool notify = true) override;
+
+  /// Add a callback group to an executor.
+  /**
+   * \sa rclcpp::Executor::add_callback_group
+   */
+  RCLCPP_PUBLIC
+  void
+  add_callback_group(
+    rclcpp::CallbackGroup::SharedPtr group_ptr,
+    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
+    bool notify = true) override;
+
+  /// Remove callback group from the executor
+  /**
+   * \sa rclcpp::Executor::remove_callback_group
+   */
+  RCLCPP_PUBLIC
+  void
+  remove_callback_group(
+    rclcpp::CallbackGroup::SharedPtr group_ptr,
+    bool notify = true) override;
+
+  /// Get callback groups that belong to executor.
+  /**
+   * \sa rclcpp::Executor::get_all_callback_groups()
+   */
+  RCLCPP_PUBLIC
+  std::vector<rclcpp::CallbackGroup::WeakPtr>
+  get_all_callback_groups() override;
+
+  /// Get callback groups that belong to executor.
+  /**
+   * \sa rclcpp::Executor::get_manually_added_callback_groups()
+   */
+  RCLCPP_PUBLIC
+  std::vector<rclcpp::CallbackGroup::WeakPtr>
+  get_manually_added_callback_groups() override;
+
+  /// Get callback groups that belong to executor.
+  /**
+   * \sa rclcpp::Executor::get_automatically_added_callback_groups_from_nodes()
+   */
+  RCLCPP_PUBLIC
+  std::vector<rclcpp::CallbackGroup::WeakPtr>
+  get_automatically_added_callback_groups_from_nodes() override;
+
+protected:
+  /// Internal implementation of spin_once
+  RCLCPP_PUBLIC
+  void
+  spin_once_impl(std::chrono::nanoseconds timeout) override;
+
+  /// Internal implementation of spin_some
+  RCLCPP_PUBLIC
+  void
+  spin_some_impl(std::chrono::nanoseconds max_duration, bool exhaustive);
+
+private:
+  RCLCPP_DISABLE_COPY(EventsExecutor)
+
+  /// Execute a provided executor event if its associated entities are available
+  void
+  execute_event(const ExecutorEvent & event);
+
+  /// Collect entities from callback groups and refresh the current collection with them
+  void
+  refresh_current_collection_from_callback_groups();
+
+  /// Refresh the current collection using the provided new_collection
+  void
+  refresh_current_collection(const rclcpp::executors::ExecutorEntitiesCollection & new_collection);
+
+  /// Create a listener callback function for the provided entity
+  std::function<void(size_t)>
+  create_entity_callback(void * entity_key, ExecutorEventType type);
+
+  /// Create a listener callback function for the provided waitable entity
+  std::function<void(size_t, int)>
+  create_waitable_callback(const rclcpp::Waitable * waitable_id);
+
+  /// Searches for the provided entity_id in the collection and returns the entity if valid
+  template<typename CollectionType>
+  typename CollectionType::EntitySharedPtr
+  retrieve_entity(typename CollectionType::Key entity_id, CollectionType & collection)
+  {
+    // Check if the entity_id is in the collection
+    auto it = collection.find(entity_id);
+    if (it == collection.end()) {
+      return nullptr;
+    }
+
+    // Check if the entity associated with the entity_id is valid
+    // and remove it from the collection if it isn't
+    auto entity = it->second.entity.lock();
+    if (!entity) {
+      collection.erase(it);
+    }
+
+    // Return the retrieved entity (this can be a nullptr if the entity was not valid)
+    return entity;
+  }
+
+  /// Queue where entities can push events
+  rclcpp::experimental::executors::EventsQueue::UniquePtr events_queue_;
+
+  std::shared_ptr<rclcpp::executors::ExecutorEntitiesCollector> entities_collector_;
+  std::shared_ptr<rclcpp::executors::ExecutorEntitiesCollection> current_entities_collection_;
+  std::shared_ptr<rclcpp::executors::ExecutorNotifyWaitable> notify_waitable_;
+
+  /// Flag used to reduce the number of unnecessary waitable events
+  std::atomic<bool> notify_waitable_event_pushed_ {false};
+
+  /// Timers manager used to track and/or execute associated timers
+  std::shared_ptr<rclcpp::experimental::TimersManager> timers_manager_;
+};
+
+}  // namespace executors
+}  // namespace experimental
+}  // namespace rclcpp
+
+#endif  // RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__EVENTS_EXECUTOR_HPP_

rclcpp/include/rclcpp/experimental/executors/events_executor/events_executor_event_types.hpp

@@ -0,0 +1,46 @@
+// Copyright 2023 iRobot Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__EVENTS_EXECUTOR_EVENT_TYPES_HPP_
+#define RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__EVENTS_EXECUTOR_EVENT_TYPES_HPP_
+
+namespace rclcpp
+{
+namespace experimental
+{
+namespace executors
+{
+
+enum ExecutorEventType
+{
+  CLIENT_EVENT,
+  SUBSCRIPTION_EVENT,
+  SERVICE_EVENT,
+  TIMER_EVENT,
+  WAITABLE_EVENT
+};
+
+struct ExecutorEvent
+{
+  const void * entity_key;
+  int waitable_data;
+  ExecutorEventType type;
+  size_t num_events;
+};
+
+}  // namespace executors
+}  // namespace experimental
+}  // namespace rclcpp
+
+#endif  // RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__EVENTS_EXECUTOR_EVENT_TYPES_HPP_

rclcpp/include/rclcpp/experimental/executors/events_executor/events_queue.hpp

@@ -0,0 +1,100 @@
+// Copyright 2023 iRobot Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__EVENTS_QUEUE_HPP_
+#define RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__EVENTS_QUEUE_HPP_
+
+#include <queue>
+
+#include "rclcpp/macros.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+#include "rclcpp/experimental/executors/events_executor/events_executor_event_types.hpp"
+
+namespace rclcpp
+{
+namespace experimental
+{
+namespace executors
+{
+
+/**
+ * @brief This abstract class can be used to implement different types of queues
+ * where `ExecutorEvent` can be stored.
+ * The derived classes should choose which underlying container to use and
+ * the strategy for pushing and popping events.
+ * For example a queue implementation may be bounded or unbounded and have
+ * different pruning strategies.
+ * Implementations may or may not check the validity of events and decide how to handle
+ * the situation where an event is not valid anymore (e.g. a subscription history cache overruns)
+ */
+class EventsQueue
+{
+public:
+  RCLCPP_SMART_PTR_ALIASES_ONLY(EventsQueue)
+
+  RCLCPP_PUBLIC
+  EventsQueue() = default;
+
+  /**
+   * @brief Destruct the object.
+   */
+  RCLCPP_PUBLIC
+  virtual ~EventsQueue() = default;
+
+  /**
+   * @brief push event into the queue
+   * @param event The event to push into the queue
+   */
+  RCLCPP_PUBLIC
+  virtual
+  void
+  enqueue(const rclcpp::experimental::executors::ExecutorEvent & event) = 0;
+
+  /**
+   * @brief Extracts an event from the queue, eventually waiting until timeout
+   * if none is available.
+   * @return true if event has been found, false if timeout
+   */
+  RCLCPP_PUBLIC
+  virtual
+  bool
+  dequeue(
+    rclcpp::experimental::executors::ExecutorEvent & event,
+    std::chrono::nanoseconds timeout = std::chrono::nanoseconds::max()) = 0;
+
+  /**
+   * @brief Test whether queue is empty
+   * @return true if the queue's size is 0, false otherwise.
+   */
+  RCLCPP_PUBLIC
+  virtual
+  bool
+  empty() const = 0;
+
+  /**
+   * @brief Returns the number of elements in the queue.
+   * @return the number of elements in the queue.
+   */
+  RCLCPP_PUBLIC
+  virtual
+  size_t
+  size() const = 0;
+};
+
+}  // namespace executors
+}  // namespace experimental
+}  // namespace rclcpp
+
+#endif  // RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__EVENTS_QUEUE_HPP_

rclcpp/include/rclcpp/experimental/executors/events_executor/simple_events_queue.hpp

@@ -0,0 +1,134 @@
+// Copyright 2023 iRobot Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__SIMPLE_EVENTS_QUEUE_HPP_
+#define RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__SIMPLE_EVENTS_QUEUE_HPP_
+
+#include <condition_variable>
+#include <mutex>
+#include <queue>
+#include <utility>
+
+#include "rclcpp/experimental/executors/events_executor/events_queue.hpp"
+
+namespace rclcpp
+{
+namespace experimental
+{
+namespace executors
+{
+
+/**
+ * @brief This class implements an EventsQueue as a simple wrapper around a std::queue.
+ * It does not perform any checks about the size of queue, which can grow
+ * unbounded without being pruned.
+ * The simplicity of this implementation makes it suitable for optimizing CPU usage.
+ */
+class SimpleEventsQueue : public EventsQueue
+{
+public:
+  RCLCPP_PUBLIC
+  ~SimpleEventsQueue() override = default;
+
+  /**
+   * @brief enqueue event into the queue
+   * Thread safe
+   * @param event The event to enqueue into the queue
+   */
+  RCLCPP_PUBLIC
+  void
+  enqueue(const rclcpp::experimental::executors::ExecutorEvent & event) override
+  {
+    rclcpp::experimental::executors::ExecutorEvent single_event = event;
+    single_event.num_events = 1;
+    {
+      std::unique_lock<std::mutex> lock(mutex_);
+      for (size_t ev = 0; ev < event.num_events; ev++) {
+        event_queue_.push(single_event);
+      }
+    }
+    events_queue_cv_.notify_one();
+  }
+
+  /**
+   * @brief waits for an event until timeout, gets a single event
+   * Thread safe
+   * @return true if event, false if timeout
+   */
+  RCLCPP_PUBLIC
+  bool
+  dequeue(
+    rclcpp::experimental::executors::ExecutorEvent & event,
+    std::chrono::nanoseconds timeout = std::chrono::nanoseconds::max()) override
+  {
+    std::unique_lock<std::mutex> lock(mutex_);
+
+    // Initialize to true because it's only needed if we have a valid timeout
+    bool has_data = true;
+    if (timeout != std::chrono::nanoseconds::max()) {
+      has_data =
+        events_queue_cv_.wait_for(lock, timeout, [this]() {return !event_queue_.empty();});
+    } else {
+      events_queue_cv_.wait(lock, [this]() {return !event_queue_.empty();});
+    }
+
+    if (has_data) {
+      event = event_queue_.front();
+      event_queue_.pop();
+      return true;
+    }
+
+    return false;
+  }
+
+  /**
+   * @brief Test whether queue is empty
+   * Thread safe
+   * @return true if the queue's size is 0, false otherwise.
+   */
+  RCLCPP_PUBLIC
+  bool
+  empty() const override
+  {
+    std::unique_lock<std::mutex> lock(mutex_);
+    return event_queue_.empty();
+  }
+
+  /**
+   * @brief Returns the number of elements in the queue.
+   * Thread safe
+   * @return the number of elements in the queue.
+   */
+  RCLCPP_PUBLIC
+  size_t
+  size() const override
+  {
+    std::unique_lock<std::mutex> lock(mutex_);
+    return event_queue_.size();
+  }
+
+private:
+  // The underlying queue implementation
+  std::queue<rclcpp::experimental::executors::ExecutorEvent> event_queue_;
+  // Mutex to protect read/write access to the queue
+  mutable std::mutex mutex_;
+  // Variable used to notify when an event is added to the queue
+  std::condition_variable events_queue_cv_;
+};
+
+}  // namespace executors
+}  // namespace experimental
+}  // namespace rclcpp
+
+#endif  // RCLCPP__EXPERIMENTAL__EXECUTORS__EVENTS_EXECUTOR__SIMPLE_EVENTS_QUEUE_HPP_

rclcpp/include/rclcpp/experimental/subscription_intra_process.hpp

@@ -118,6 +118,13 @@ public:
         return nullptr;
       }
     }
+
+    if (this->buffer_->has_data()) {
+      // If there is data still to be processed, indicate to the
+      // executor or waitset by triggering the guard condition.
+      this->trigger_guard_condition();
+    }
+
     return std::static_pointer_cast<void>(
       std::make_shared<std::pair<ConstMessageSharedPtr, MessageUniquePtr>>(
         std::pair<ConstMessageSharedPtr, MessageUniquePtr>(

rclcpp/include/rclcpp/experimental/subscription_intra_process_buffer.hpp

@@ -31,6 +31,8 @@
 #include "rclcpp/qos.hpp"
 #include "rclcpp/type_support_decl.hpp"
 
+#include "tracetools/tracetools.h"
+
 namespace rclcpp
 {
 namespace experimental
@@ -91,6 +93,10 @@ public:
       buffer_type,
       qos_profile,
       std::make_shared<Alloc>(subscribed_type_allocator_));
+    TRACEPOINT(
+      rclcpp_ipb_to_subscription,
+      static_cast<const void *>(buffer_.get()),
+      static_cast<const void *>(this));
   }
 
   bool

rclcpp/include/rclcpp/experimental/timers_manager.hpp

@@ -0,0 +1,553 @@
+// Copyright 2023 iRobot Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__EXPERIMENTAL__TIMERS_MANAGER_HPP_
+#define RCLCPP__EXPERIMENTAL__TIMERS_MANAGER_HPP_
+
+#include <algorithm>
+#include <atomic>
+#include <chrono>
+#include <condition_variable>
+#include <functional>
+#include <memory>
+#include <mutex>
+#include <thread>
+#include <utility>
+#include <vector>
+
+#include "rclcpp/context.hpp"
+#include "rclcpp/timer.hpp"
+
+namespace rclcpp
+{
+namespace experimental
+{
+
+/**
+ * @brief This class provides a way for storing and executing timer objects.
+ * It provides APIs to suit the needs of different applications and execution models.
+ * All public APIs provided by this class are thread-safe.
+ *
+ * Timers management
+ * This class provides APIs to add/remove timers to/from an internal storage.
+ * It keeps a list of weak pointers from added timers, and locks them only when
+ * they need to be executed or modified.
+ * Timers are kept ordered in a binary-heap priority queue.
+ * Calls to add/remove APIs will temporarily block the execution of the timers and
+ * will require to reorder the internal priority queue.
+ * Because of this, they have a not-negligible impact on the performance.
+ *
+ * Timers execution
+ * The most efficient use of this class consists in letting a TimersManager object
+ * to spawn a thread where timers are monitored and optionally executed.
+ * This can be controlled via the `start` and `stop` methods.
+ * Ready timers can either be executed or an on_ready_callback can be used to notify
+ * other entities that they are ready and need to be executed.
+ * Other APIs allow to directly execute a given timer.
+ *
+ * This class assumes that the `execute_callback()` API of the stored timers is never
+ * called by other entities, but it can only be called from here.
+ * If this assumption is not respected, the heap property may be invalidated,
+ * so timers may be executed out of order, without this object noticing it.
+ *
+ */
+class TimersManager
+{
+public:
+  RCLCPP_SMART_PTR_DEFINITIONS_NOT_COPYABLE(TimersManager)
+
+  /**
+   * @brief Construct a new TimersManager object
+   *
+   * @param context custom context to be used.
+   * Shared ownership of the context is held until destruction.
+   * @param on_ready_callback The timers on ready callback. The presence of this function
+   * indicates what to do when the TimersManager is running and a timer becomes ready.
+   * The TimersManager is considered "running" when the `start` method has been called.
+   * If it's callable, it will be invoked instead of the timer callback.
+   * If it's not callable, then the TimersManager will
+   * directly execute timers when they are ready.
+   * All the methods that execute a given timer (e.g. `execute_head_timer`
+   * or `execute_ready_timer`) without the TimersManager being `running`, i.e.
+   * without actually explicitly waiting for the timer to become ready, will ignore this
+   * callback.
+   */
+  RCLCPP_PUBLIC
+  TimersManager(
+    std::shared_ptr<rclcpp::Context> context,
+    std::function<void(const rclcpp::TimerBase *)> on_ready_callback = nullptr);
+
+  /**
+   * @brief Destruct the TimersManager object making sure to stop thread and release memory.
+   */
+  RCLCPP_PUBLIC
+  ~TimersManager();
+
+  /**
+   * @brief Adds a new timer to the storage, maintaining weak ownership of it.
+   * Function is thread safe and it can be called regardless of the state of the timers thread.
+   *
+   * @param timer the timer to add.
+   * @throws std::invalid_argument if timer is a nullptr.
+   */
+  RCLCPP_PUBLIC
+  void add_timer(rclcpp::TimerBase::SharedPtr timer);
+
+  /**
+   * @brief Remove a single timer from the object storage.
+   * Will do nothing if the timer was not being stored here.
+   * Function is thread safe and it can be called regardless of the state of the timers thread.
+   *
+   * @param timer the timer to remove.
+   */
+  RCLCPP_PUBLIC
+  void remove_timer(rclcpp::TimerBase::SharedPtr timer);
+
+  /**
+   * @brief Remove all the timers stored in the object.
+   * Function is thread safe and it can be called regardless of the state of the timers thread.
+   */
+  RCLCPP_PUBLIC
+  void clear();
+
+  /**
+   * @brief Starts a thread that takes care of executing the timers stored in this object.
+   * Function will throw an error if the timers thread was already running.
+   */
+  RCLCPP_PUBLIC
+  void start();
+
+  /**
+   * @brief Stops the timers thread.
+   * Will do nothing if the timer thread was not running.
+   */
+  RCLCPP_PUBLIC
+  void stop();
+
+  /**
+   * @brief Get the number of timers that are currently ready.
+   * This function is thread safe.
+   *
+   * @return size_t number of ready timers.
+   * @throws std::runtime_error if the timers thread was already running.
+   */
+  RCLCPP_PUBLIC
+  size_t get_number_ready_timers();
+
+  /**
+   * @brief Executes head timer if ready.
+   * This function is thread safe.
+   * This function will try to execute the timer callback regardless of whether
+   * the TimersManager on_ready_callback was passed during construction.
+   *
+   * @return true if head timer was ready.
+   * @throws std::runtime_error if the timers thread was already running.
+   */
+  RCLCPP_PUBLIC
+  bool execute_head_timer();
+
+  /**
+   * @brief Executes timer identified by its ID.
+   * This function is thread safe.
+   * This function will try to execute the timer callback regardless of whether
+   * the TimersManager on_ready_callback was passed during construction.
+   *
+   * @param timer_id the timer ID of the timer to execute
+   */
+  RCLCPP_PUBLIC
+  void execute_ready_timer(const rclcpp::TimerBase * timer_id);
+
+  /**
+   * @brief Get the amount of time before the next timer triggers.
+   * This function is thread safe.
+   *
+   * @return std::chrono::nanoseconds to wait,
+   * the returned value could be negative if the timer is already expired
+   * or std::chrono::nanoseconds::max() if there are no timers stored in the object.
+   * @throws std::runtime_error if the timers thread was already running.
+   */
+  RCLCPP_PUBLIC
+  std::chrono::nanoseconds get_head_timeout();
+
+private:
+  RCLCPP_DISABLE_COPY(TimersManager)
+
+  using TimerPtr = rclcpp::TimerBase::SharedPtr;
+  using WeakTimerPtr = rclcpp::TimerBase::WeakPtr;
+
+  // Forward declaration
+  class TimersHeap;
+
+  /**
+   * @brief This class allows to store weak pointers to timers in a heap-like data structure.
+   * The root of the heap is the timer that triggers first.
+   * Since this class uses weak ownership, it is not guaranteed that it represents a valid heap
+   * at any point in time as timers could go out of scope, thus invalidating it.
+   * The "validate_and_lock" API allows to restore the heap property and also returns a locked version
+   * of the timers heap.
+   * This class is not thread safe and requires external mutexes to protect its usage.
+   */
+  class WeakTimersHeap
+  {
+public:
+    /**
+     * @brief Add a new timer to the heap. After the addition, the heap property is enforced.
+     *
+     * @param timer new timer to add.
+     * @return true if timer has been added, false if it was already there.
+     */
+    bool add_timer(TimerPtr timer)
+    {
+      TimersHeap locked_heap = this->validate_and_lock();
+      bool added = locked_heap.add_timer(std::move(timer));
+
+      if (added) {
+        // Re-create the weak heap with the new timer added
+        this->store(locked_heap);
+      }
+
+      return added;
+    }
+
+    /**
+     * @brief Remove a timer from the heap. After the removal, the heap property is enforced.
+     *
+     * @param timer timer to remove.
+     * @return true if timer has been removed, false if it was not there.
+     */
+    bool remove_timer(TimerPtr timer)
+    {
+      TimersHeap locked_heap = this->validate_and_lock();
+      bool removed = locked_heap.remove_timer(std::move(timer));
+
+      if (removed) {
+        // Re-create the weak heap with the timer removed
+        this->store(locked_heap);
+      }
+
+      return removed;
+    }
+
+    /**
+     * @brief Retrieve the timer identified by the key
+     * @param timer_id The ID of the timer to retrieve.
+     * @return TimerPtr if there's a timer associated with the ID, nullptr otherwise
+     */
+    TimerPtr get_timer(const rclcpp::TimerBase * timer_id)
+    {
+      for (auto & weak_timer : weak_heap_) {
+        auto timer = weak_timer.lock();
+        if (timer.get() == timer_id) {
+          return timer;
+        }
+      }
+      return nullptr;
+    }
+
+    /**
+     * @brief Returns a const reference to the front element.
+     */
+    const WeakTimerPtr & front() const
+    {
+      return weak_heap_.front();
+    }
+
+    /**
+     * @brief Returns whether the heap is empty or not.
+     */
+    bool empty() const
+    {
+      return weak_heap_.empty();
+    }
+
+    /**
+     * @brief This function restores the current object as a valid heap
+     * and it returns a locked version of it.
+     * Timers that went out of scope are removed from the container.
+     * It is the only public API to access and manipulate the stored timers.
+     *
+     * @return TimersHeap owned timers corresponding to the current object
+     */
+    TimersHeap validate_and_lock()
+    {
+      TimersHeap locked_heap;
+      bool any_timer_destroyed = false;
+
+      for (auto weak_timer : weak_heap_) {
+        auto timer = weak_timer.lock();
+        if (timer) {
+          // This timer is valid, so add it to the locked heap
+          // Note: we access friend private `owned_heap_` member field.
+          locked_heap.owned_heap_.push_back(std::move(timer));
+        } else {
+          // This timer went out of scope, so we don't add it to locked heap
+          // and we mark the corresponding flag.
+          // It's not needed to erase it from weak heap, as we are going to re-heapify.
+          // Note: we can't exit from the loop here, as we need to find all valid timers.
+          any_timer_destroyed = true;
+        }
+      }
+
+      // If a timer has gone out of scope, then the remaining elements do not represent
+      // a valid heap anymore. We need to re-heapify the timers heap.
+      if (any_timer_destroyed) {
+        locked_heap.heapify();
+        // Re-create the weak heap now that elements have been heapified again
+        this->store(locked_heap);
+      }
+
+      return locked_heap;
+    }
+
+    /**
+     * @brief This function allows to recreate the heap of weak pointers
+     * from an heap of owned pointers.
+     * It is required to be called after a locked TimersHeap generated from this object
+     * has been modified in any way (e.g. timers triggered, added, removed).
+     *
+     * @param heap timers heap to store as weak pointers
+     */
+    void store(const TimersHeap & heap)
+    {
+      weak_heap_.clear();
+      // Note: we access friend private `owned_heap_` member field.
+      for (auto t : heap.owned_heap_) {
+        weak_heap_.push_back(t);
+      }
+    }
+
+    /**
+     * @brief Remove all timers from the heap.
+     */
+    void clear()
+    {
+      weak_heap_.clear();
+    }
+
+private:
+    std::vector<WeakTimerPtr> weak_heap_;
+  };
+
+  /**
+   * @brief This class is the equivalent of WeakTimersHeap but with ownership of the timers.
+   * It can be generated by locking the weak version.
+   * It provides operations to manipulate the heap.
+   * This class is not thread safe and requires external mutexes to protect its usage.
+   */
+  class TimersHeap
+  {
+public:
+    /**
+     * @brief Try to add a new timer to the heap.
+     * After the addition, the heap property is preserved.
+     * @param timer new timer to add.
+     * @return true if timer has been added, false if it was already there.
+     */
+    bool add_timer(TimerPtr timer)
+    {
+      // Nothing to do if the timer is already stored here
+      auto it = std::find(owned_heap_.begin(), owned_heap_.end(), timer);
+      if (it != owned_heap_.end()) {
+        return false;
+      }
+
+      owned_heap_.push_back(std::move(timer));
+      std::push_heap(owned_heap_.begin(), owned_heap_.end(), timer_greater);
+
+      return true;
+    }
+
+    /**
+     * @brief Try to remove a timer from the heap.
+     * After the removal, the heap property is preserved.
+     * @param timer timer to remove.
+     * @return true if timer has been removed, false if it was not there.
+     */
+    bool remove_timer(TimerPtr timer)
+    {
+      // Nothing to do if the timer is not stored here
+      auto it = std::find(owned_heap_.begin(), owned_heap_.end(), timer);
+      if (it == owned_heap_.end()) {
+        return false;
+      }
+
+      owned_heap_.erase(it);
+      this->heapify();
+
+      return true;
+    }
+
+    /**
+     * @brief Returns a reference to the front element.
+     * @return reference to front element.
+     */
+    TimerPtr & front()
+    {
+      return owned_heap_.front();
+    }
+
+    /**
+     * @brief Returns a const reference to the front element.
+     * @return const reference to front element.
+     */
+    const TimerPtr & front() const
+    {
+      return owned_heap_.front();
+    }
+
+    /**
+     * @brief Returns whether the heap is empty or not.
+     * @return true if the heap is empty.
+     */
+    bool empty() const
+    {
+      return owned_heap_.empty();
+    }
+
+    /**
+     * @brief Returns the size of the heap.
+     * @return the number of valid timers in the heap.
+     */
+    size_t size() const
+    {
+      return owned_heap_.size();
+    }
+
+    /**
+     * @brief Get the number of timers that are currently ready.
+     * @return size_t number of ready timers.
+     */
+    size_t get_number_ready_timers() const
+    {
+      size_t ready_timers = 0;
+
+      for (TimerPtr t : owned_heap_) {
+        if (t->is_ready()) {
+          ready_timers++;
+        }
+      }
+
+      return ready_timers;
+    }
+
+    /**
+    * @brief Restore a valid heap after the root value has been replaced (e.g. timer triggered).
+    */
+    void heapify_root()
+    {
+      // The following code is a more efficient version than doing
+      // pop_heap, pop_back, push_back, push_heap
+      // as it removes the need for the last push_heap
+
+      // Push the modified element (i.e. the current root) at the bottom of the heap
+      owned_heap_.push_back(owned_heap_[0]);
+      // Exchange first and last-1 elements and reheapify
+      std::pop_heap(owned_heap_.begin(), owned_heap_.end(), timer_greater);
+      // Remove last element
+      owned_heap_.pop_back();
+    }
+
+    /**
+     * @brief Completely restores the structure to a valid heap
+     */
+    void heapify()
+    {
+      std::make_heap(owned_heap_.begin(), owned_heap_.end(), timer_greater);
+    }
+
+    /**
+     * @brief Helper function to clear the "on_reset_callback" on all associated timers.
+     */
+    void clear_timers_on_reset_callbacks()
+    {
+      for (TimerPtr & t : owned_heap_) {
+        t->clear_on_reset_callback();
+      }
+    }
+
+    /**
+     * @brief Friend declaration to allow the `validate_and_lock()` function to access the
+     * underlying heap container
+     */
+    friend TimersHeap WeakTimersHeap::validate_and_lock();
+
+    /**
+     * @brief Friend declaration to allow the `store()` function to access the
+     * underlying heap container
+     */
+    friend void WeakTimersHeap::store(const TimersHeap & heap);
+
+private:
+    /**
+     * @brief Comparison function between timers.
+     * @return true if `a` triggers after `b`.
+     */
+    static bool timer_greater(TimerPtr a, TimerPtr b)
+    {
+      // TODO(alsora): this can cause an error if timers are using different clocks
+      return a->time_until_trigger() > b->time_until_trigger();
+    }
+
+    std::vector<TimerPtr> owned_heap_;
+  };
+
+  /**
+   * @brief Implements a loop that keeps executing ready timers.
+   * This function is executed in the timers thread.
+   */
+  void run_timers();
+
+  /**
+   * @brief Get the amount of time before the next timer triggers.
+   * This function is not thread safe, acquire a mutex before calling it.
+   *
+   * @return std::chrono::nanoseconds to wait,
+   * the returned value could be negative if the timer is already expired
+   * or std::chrono::nanoseconds::max() if the heap is empty.
+   * This function is not thread safe, acquire the timers_mutex_ before calling it.
+   */
+  std::chrono::nanoseconds get_head_timeout_unsafe();
+
+  /**
+   * @brief Executes all the timers currently ready when the function is invoked
+   * while keeping the heap correctly sorted.
+   * This function is not thread safe, acquire the timers_mutex_ before calling it.
+   */
+  void execute_ready_timers_unsafe();
+
+  // Callback to be called when timer is ready
+  std::function<void(const rclcpp::TimerBase *)> on_ready_callback_ = nullptr;
+
+  // Thread used to run the timers execution task
+  std::thread timers_thread_;
+  // Protects access to timers
+  std::mutex timers_mutex_;
+  // Protects access to stop()
+  std::mutex stop_mutex_;
+  // Notifies the timers thread whenever timers are added/removed
+  std::condition_variable timers_cv_;
+  // Flag used as predicate by timers_cv_ that denotes one or more timers being added/removed
+  bool timers_updated_ {false};
+  // Indicates whether the timers thread is currently running or not
+  std::atomic<bool> running_ {false};
+  // Parent context used to understand if ROS is still active
+  std::shared_ptr<rclcpp::Context> context_;
+  // Timers heap storage with weak ownership
+  WeakTimersHeap weak_timers_heap_;
+};
+
+}  // namespace experimental
+}  // namespace rclcpp
+
+#endif  // RCLCPP__EXPERIMENTAL__TIMERS_MANAGER_HPP_

rclcpp/include/rclcpp/generic_subscription.hpp

@@ -84,7 +84,7 @@ public:
       options.to_rcl_subscription_options(qos),
       options.event_callbacks,
       options.use_default_callbacks,
-      true),
+      DeliveredMessageKind::SERIALIZED_MESSAGE),
     callback_(callback),
     ts_lib_(ts_lib)
   {}
@@ -123,6 +123,31 @@ public:
   RCLCPP_PUBLIC
   void return_serialized_message(std::shared_ptr<rclcpp::SerializedMessage> & message) override;
 
+
+  // DYNAMIC TYPE ==================================================================================
+  RCLCPP_PUBLIC
+  rclcpp::dynamic_typesupport::DynamicMessageType::SharedPtr get_shared_dynamic_message_type()
+  override;
+
+  RCLCPP_PUBLIC
+  rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr get_shared_dynamic_message() override;
+
+  RCLCPP_PUBLIC
+  rclcpp::dynamic_typesupport::DynamicSerializationSupport::SharedPtr
+  get_shared_dynamic_serialization_support() override;
+
+  RCLCPP_PUBLIC
+  rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr create_dynamic_message() override;
+
+  RCLCPP_PUBLIC
+  void return_dynamic_message(
+    rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr & message) override;
+
+  RCLCPP_PUBLIC
+  void handle_dynamic_message(
+    const rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr & message,
+    const rclcpp::MessageInfo & message_info) override;
+
 private:
   RCLCPP_DISABLE_COPY(GenericSubscription)
 

rclcpp/include/rclcpp/node_interfaces/node_base.hpp

@@ -121,10 +121,19 @@ public:
   std::atomic_bool &
   get_associated_with_executor_atomic() override;
 
+  [[deprecated("Use get_shared_notify_guard_condition or trigger_notify_guard_condition instead")]]
   RCLCPP_PUBLIC
   rclcpp::GuardCondition &
   get_notify_guard_condition() override;
 
+  RCLCPP_PUBLIC
+  rclcpp::GuardCondition::SharedPtr
+  get_shared_notify_guard_condition() override;
+
+  RCLCPP_PUBLIC
+  void
+  trigger_notify_guard_condition() override;
+
   RCLCPP_PUBLIC
   bool
   get_use_intra_process_default() const override;
@@ -153,7 +162,7 @@ private:
 
   /// Guard condition for notifying the Executor of changes to this node.
   mutable std::recursive_mutex notify_guard_condition_mutex_;
-  rclcpp::GuardCondition notify_guard_condition_;
+  std::shared_ptr<rclcpp::GuardCondition> notify_guard_condition_;
   bool notify_guard_condition_is_valid_;
 };
 

rclcpp/include/rclcpp/node_interfaces/node_base_interface.hpp

@@ -148,13 +148,33 @@ public:
   /**
    * For example, this should be notified when a publisher is added or removed.
    *
-   * \return the GuardCondition if it is valid, else thow runtime error
+   * \return the GuardCondition if it is valid, else throw runtime error
    */
   RCLCPP_PUBLIC
   virtual
   rclcpp::GuardCondition &
   get_notify_guard_condition() = 0;
 
+  /// Return a guard condition that should be notified when the internal node state changes.
+  /**
+   * For example, this should be notified when a publisher is added or removed.
+   *
+   * \return the GuardCondition if it is valid, else nullptr
+   */
+  RCLCPP_PUBLIC
+  virtual
+  rclcpp::GuardCondition::SharedPtr
+  get_shared_notify_guard_condition() = 0;
+
+  /// Trigger the guard condition that notifies of internal node state changes.
+  /**
+   * For example, this should be notified when a publisher is added or removed.
+   */
+  RCLCPP_PUBLIC
+  virtual
+  void
+  trigger_notify_guard_condition() = 0;
+
   /// Return the default preference for using intra process communication.
   RCLCPP_PUBLIC
   virtual

rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp

@@ -57,7 +57,8 @@ public:
     node_namespace_(info.node_namespace),
     topic_type_(info.topic_type),
     endpoint_type_(static_cast<rclcpp::EndpointType>(info.endpoint_type)),
-    qos_profile_({info.qos_profile.history, info.qos_profile.depth}, info.qos_profile)
+    qos_profile_({info.qos_profile.history, info.qos_profile.depth}, info.qos_profile),
+    topic_type_hash_(info.topic_type_hash)
   {
     std::copy(info.endpoint_gid, info.endpoint_gid + RMW_GID_STORAGE_SIZE, endpoint_gid_.begin());
   }
@@ -122,6 +123,16 @@ public:
   const rclcpp::QoS &
   qos_profile() const;
 
+  /// Get a mutable reference to the type hash of the topic endpoint.
+  RCLCPP_PUBLIC
+  rosidl_type_hash_t &
+  topic_type_hash();
+
+  /// Get a const reference to the type hash of the topic endpoint.
+  RCLCPP_PUBLIC
+  const rosidl_type_hash_t &
+  topic_type_hash() const;
+
 private:
   std::string node_name_;
   std::string node_namespace_;
@@ -129,6 +140,7 @@ private:
   rclcpp::EndpointType endpoint_type_;
   std::array<uint8_t, RMW_GID_STORAGE_SIZE> endpoint_gid_;
   rclcpp::QoS qos_profile_;
+  rosidl_type_hash_t topic_type_hash_;
 };
 
 namespace node_interfaces

rclcpp/include/rclcpp/publisher.hpp

@@ -484,6 +484,10 @@ protected:
     if (!msg) {
       throw std::runtime_error("cannot publish msg which is a null pointer");
     }
+    TRACEPOINT(
+      rclcpp_intra_publish,
+      static_cast<const void *>(publisher_handle_.get()),
+      msg.get());
 
     ipm->template do_intra_process_publish<PublishedType, ROSMessageType, AllocatorT>(
       intra_process_publisher_id_,
@@ -502,6 +506,10 @@ protected:
     if (!msg) {
       throw std::runtime_error("cannot publish msg which is a null pointer");
     }
+    TRACEPOINT(
+      rclcpp_intra_publish,
+      static_cast<const void *>(publisher_handle_.get()),
+      msg.get());
 
     ipm->template do_intra_process_publish<ROSMessageType, ROSMessageType, AllocatorT>(
       intra_process_publisher_id_,
@@ -521,6 +529,10 @@ protected:
     if (!msg) {
       throw std::runtime_error("cannot publish msg which is a null pointer");
     }
+    TRACEPOINT(
+      rclcpp_intra_publish,
+      static_cast<const void *>(publisher_handle_.get()),
+      msg.get());
 
     return ipm->template do_intra_process_publish_and_return_shared<ROSMessageType, ROSMessageType,
              AllocatorT>(

rclcpp/include/rclcpp/rclcpp.hpp

@@ -117,6 +117,18 @@
  * - Allocator related items:
  *   - rclcpp/allocator/allocator_common.hpp
  *   - rclcpp/allocator/allocator_deleter.hpp
+ * - Dynamic typesupport wrappers
+ *   - rclcpp::dynamic_typesupport::DynamicMessage
+ *   - rclcpp::dynamic_typesupport::DynamicMessageType
+ *   - rclcpp::dynamic_typesupport::DynamicMessageTypeBuilder
+ *   - rclcpp::dynamic_typesupport::DynamicSerializationSupport
+ *   - rclcpp/dynamic_typesupport/dynamic_message.hpp
+ *   - rclcpp/dynamic_typesupport/dynamic_message_type.hpp
+ *   - rclcpp/dynamic_typesupport/dynamic_message_type_builder.hpp
+ *   - rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp
+ * - Dynamic typesupport
+ *   - rclcpp::dynamic_typesupport::DynamicMessageTypeSupport
+ *   - rclcpp/dynamic_typesupport/dynamic_message_type_support.hpp
  * - Generic publisher
  *   - rclcpp::Node::create_generic_publisher()
  *   - rclcpp::GenericPublisher

rclcpp/include/rclcpp/subscription.hpp

@@ -144,7 +144,7 @@ public:
       // NOTE(methylDragon): Passing these args separately is necessary for event binding
       options.event_callbacks,
       options.use_default_callbacks,
-      callback.is_serialized_message_callback()),
+      callback.is_serialized_message_callback() ? DeliveredMessageKind::SERIALIZED_MESSAGE : DeliveredMessageKind::ROS_MESSAGE),  // NOLINT
     any_callback_(callback),
     options_(options),
     message_memory_strategy_(message_memory_strategy)
@@ -388,6 +388,57 @@ public:
     return any_callback_.use_take_shared_method();
   }
 
+  // DYNAMIC TYPE ==================================================================================
+  // TODO(methylDragon): Reorder later
+  // TODO(methylDragon): Implement later...
+  rclcpp::dynamic_typesupport::DynamicMessageType::SharedPtr
+  get_shared_dynamic_message_type() override
+  {
+    throw rclcpp::exceptions::UnimplementedError(
+            "get_shared_dynamic_message_type is not implemented for Subscription");
+  }
+
+  rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr
+  get_shared_dynamic_message() override
+  {
+    throw rclcpp::exceptions::UnimplementedError(
+            "get_shared_dynamic_message is not implemented for Subscription");
+  }
+
+  rclcpp::dynamic_typesupport::DynamicSerializationSupport::SharedPtr
+  get_shared_dynamic_serialization_support() override
+  {
+    throw rclcpp::exceptions::UnimplementedError(
+            "get_shared_dynamic_serialization_support is not implemented for Subscription");
+  }
+
+  rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr
+  create_dynamic_message() override
+  {
+    throw rclcpp::exceptions::UnimplementedError(
+            "create_dynamic_message is not implemented for Subscription");
+  }
+
+  void
+  return_dynamic_message(
+    rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr & message) override
+  {
+    (void) message;
+    throw rclcpp::exceptions::UnimplementedError(
+            "return_dynamic_message is not implemented for Subscription");
+  }
+
+  void
+  handle_dynamic_message(
+    const rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr & message,
+    const rclcpp::MessageInfo & message_info) override
+  {
+    (void) message;
+    (void) message_info;
+    throw rclcpp::exceptions::UnimplementedError(
+            "handle_dynamic_message is not implemented for Subscription");
+  }
+
 private:
   RCLCPP_DISABLE_COPY(Subscription)
 

rclcpp/include/rclcpp/subscription_base.hpp

@@ -31,6 +31,9 @@
 
 #include "rclcpp/any_subscription_callback.hpp"
 #include "rclcpp/detail/cpp_callback_trampoline.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message_type.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp"
 #include "rclcpp/experimental/intra_process_manager.hpp"
 #include "rclcpp/experimental/subscription_intra_process_base.hpp"
 #include "rclcpp/macros.hpp"
@@ -60,6 +63,27 @@ namespace experimental
 class IntraProcessManager;
 }  // namespace experimental
 
+/// The kind of message that the subscription delivers in its callback, used by the executor
+/**
+ * This enum needs to exist because the callback handle is not accessible to the executor's scope.
+ *
+ * "Kind" is used since what is being delivered is a category of messages, for example, there are
+ * different ROS message types that can be delivered, but they're all ROS messages.
+ *
+ * As a concrete example, all of the following callbacks will be considered ROS_MESSAGE for
+ * DeliveredMessageKind:
+ *   - void callback(const std_msgs::msg::String &)
+ *   - void callback(const std::string &)  // type adaption
+ *   - void callback(std::unique_ptr<std_msgs::msg::String>)
+ */
+enum class DeliveredMessageKind : uint8_t
+{
+  INVALID = 0,
+  ROS_MESSAGE = 1,  // The subscription delivers a ROS message to its callback
+  SERIALIZED_MESSAGE = 2,  // The subscription delivers a serialized message to its callback
+  DYNAMIC_MESSAGE = 3,  // The subscription delivers a dynamic message to its callback
+};
+
 /// Virtual base class for subscriptions. This pattern allows us to iterate over different template
 /// specializations of Subscription, among other things.
 class SubscriptionBase : public std::enable_shared_from_this<SubscriptionBase>
@@ -76,7 +100,8 @@ public:
    * \param[in] type_support_handle rosidl type support struct, for the Message type of the topic.
    * \param[in] topic_name Name of the topic to subscribe to.
    * \param[in] subscription_options Options for the subscription.
-   * \param[in] is_serialized is true if the message will be delivered still serialized
+   * \param[in] delivered_message_kind Enum flag to change how the message will be received and
+   *            delivered
    */
   RCLCPP_PUBLIC
   SubscriptionBase(
@@ -86,7 +111,7 @@ public:
     const rcl_subscription_options_t & subscription_options,
     const SubscriptionEventCallbacks & event_callbacks,
     bool use_default_callbacks,
-    bool is_serialized = false);
+    DeliveredMessageKind delivered_message_kind = DeliveredMessageKind::ROS_MESSAGE);
 
   /// Destructor.
   RCLCPP_PUBLIC
@@ -235,6 +260,14 @@ public:
   bool
   is_serialized() const;
 
+  /// Return the type of the subscription.
+  /**
+   * \return `DeliveredMessageKind`, which adjusts how messages are received and delivered.
+   */
+  RCLCPP_PUBLIC
+  DeliveredMessageKind
+  get_subscription_type() const;
+
   /// Get matching publisher count.
   /** \return The number of publishers on this topic. */
   RCLCPP_PUBLIC
@@ -535,6 +568,49 @@ public:
   rclcpp::ContentFilterOptions
   get_content_filter() const;
 
+  // DYNAMIC TYPE ==================================================================================
+  // TODO(methylDragon): Reorder later
+  RCLCPP_PUBLIC
+  virtual
+  rclcpp::dynamic_typesupport::DynamicMessageType::SharedPtr
+  get_shared_dynamic_message_type() = 0;
+
+  RCLCPP_PUBLIC
+  virtual
+  rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr
+  get_shared_dynamic_message() = 0;
+
+  RCLCPP_PUBLIC
+  virtual
+  rclcpp::dynamic_typesupport::DynamicSerializationSupport::SharedPtr
+  get_shared_dynamic_serialization_support() = 0;
+
+  /// Borrow a new serialized message (this clones!)
+  /** \return Shared pointer to a rclcpp::dynamic_typesupport::DynamicMessage. */
+  RCLCPP_PUBLIC
+  virtual
+  rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr
+  create_dynamic_message() = 0;
+
+  RCLCPP_PUBLIC
+  virtual
+  void
+  return_dynamic_message(rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr & message) = 0;
+
+  RCLCPP_PUBLIC
+  virtual
+  void
+  handle_dynamic_message(
+    const rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr & message,
+    const rclcpp::MessageInfo & message_info) = 0;
+
+  RCLCPP_PUBLIC
+  bool
+  take_dynamic_message(
+    rclcpp::dynamic_typesupport::DynamicMessage & message_out,
+    rclcpp::MessageInfo & message_info_out);
+  // ===============================================================================================
+
 protected:
   template<typename EventCallbackT>
   void
@@ -587,7 +663,7 @@ private:
   RCLCPP_DISABLE_COPY(SubscriptionBase)
 
   rosidl_message_type_support_t type_support_;
-  bool is_serialized_;
+  DeliveredMessageKind delivered_message_type_;
 
   std::atomic<bool> subscription_in_use_by_wait_set_{false};
   std::atomic<bool> intra_process_subscription_waitable_in_use_by_wait_set_{false};

rclcpp/include/rclcpp/wait_set_policies/detail/storage_policy_common.hpp

@@ -104,7 +104,7 @@ protected:
       // TODO(wjwwood): support custom allocator, maybe restrict to polymorphic allocator
       rcl_get_default_allocator());
     if (RCL_RET_OK != ret) {
-      rclcpp::exceptions::throw_from_rcl_error(ret);
+      rclcpp::exceptions::throw_from_rcl_error(ret, "Failed to create wait set");
     }
 
     // (Re)build the wait set for the first time.
@@ -192,8 +192,7 @@ protected:
       size_t services_from_waitables = 0;
       size_t events_from_waitables = 0;
       for (const auto & waitable_entry : waitables) {
-        auto waitable_ptr_pair = get_raw_pointer_from_smart_pointer(waitable_entry.waitable);
-        if (nullptr == waitable_ptr_pair.second) {
+        if (!waitable_entry.waitable) {
           // In this case it was probably stored as a weak_ptr, but is now locking to nullptr.
           if (HasStrongOwnership) {
             // This will not happen in fixed sized storage, as it holds
@@ -204,13 +203,13 @@ protected:
           needs_pruning_ = true;
           continue;
         }
-        rclcpp::Waitable & waitable = *waitable_ptr_pair.second;
-        subscriptions_from_waitables += waitable.get_number_of_ready_subscriptions();
-        guard_conditions_from_waitables += waitable.get_number_of_ready_guard_conditions();
-        timers_from_waitables += waitable.get_number_of_ready_timers();
-        clients_from_waitables += waitable.get_number_of_ready_clients();
-        services_from_waitables += waitable.get_number_of_ready_services();
-        events_from_waitables += waitable.get_number_of_ready_events();
+        const auto & waitable = waitable_entry.waitable;
+        subscriptions_from_waitables += waitable->get_number_of_ready_subscriptions();
+        guard_conditions_from_waitables += waitable->get_number_of_ready_guard_conditions();
+        timers_from_waitables += waitable->get_number_of_ready_timers();
+        clients_from_waitables += waitable->get_number_of_ready_clients();
+        services_from_waitables += waitable->get_number_of_ready_services();
+        events_from_waitables += waitable->get_number_of_ready_events();
       }
       rcl_ret_t ret = rcl_wait_set_resize(
         &rcl_wait_set_,
@@ -222,7 +221,7 @@ protected:
         events_from_waitables
       );
       if (RCL_RET_OK != ret) {
-        rclcpp::exceptions::throw_from_rcl_error(ret);
+        rclcpp::exceptions::throw_from_rcl_error(ret, "Couldn't resize the wait set");
       }
       was_resized = true;
       // Assumption: the calling code ensures this function is not called
@@ -238,15 +237,13 @@ protected:
     if (!was_resized) {
       rcl_ret_t ret = rcl_wait_set_clear(&rcl_wait_set_);
       if (RCL_RET_OK != ret) {
-        rclcpp::exceptions::throw_from_rcl_error(ret);
+        rclcpp::exceptions::throw_from_rcl_error(ret, "Couldn't clear the wait set");
       }
     }
 
     // Add subscriptions.
     for (const auto & subscription_entry : subscriptions) {
-      auto subscription_ptr_pair =
-        get_raw_pointer_from_smart_pointer(subscription_entry.subscription);
-      if (nullptr == subscription_ptr_pair.second) {
+      if (!subscription_entry.subscription) {
         // In this case it was probably stored as a weak_ptr, but is now locking to nullptr.
         if (HasStrongOwnership) {
           // This will not happen in fixed sized storage, as it holds
@@ -257,12 +254,13 @@ protected:
         needs_pruning_ = true;
         continue;
       }
+
       rcl_ret_t ret = rcl_wait_set_add_subscription(
         &rcl_wait_set_,
-        subscription_ptr_pair.second->get_subscription_handle().get(),
+        subscription_entry.subscription->get_subscription_handle().get(),
         nullptr);
       if (RCL_RET_OK != ret) {
-        rclcpp::exceptions::throw_from_rcl_error(ret);
+        rclcpp::exceptions::throw_from_rcl_error(ret, "Couldn't fill wait set");
       }
     }
 
@@ -271,8 +269,7 @@ protected:
       [this](const auto & inner_guard_conditions)
       {
         for (const auto & guard_condition : inner_guard_conditions) {
-          auto guard_condition_ptr_pair = get_raw_pointer_from_smart_pointer(guard_condition);
-          if (nullptr == guard_condition_ptr_pair.second) {
+          if (!guard_condition) {
             // In this case it was probably stored as a weak_ptr, but is now locking to nullptr.
             if (HasStrongOwnership) {
               // This will not happen in fixed sized storage, as it holds
@@ -285,10 +282,10 @@ protected:
           }
           rcl_ret_t ret = rcl_wait_set_add_guard_condition(
             &rcl_wait_set_,
-            &guard_condition_ptr_pair.second->get_rcl_guard_condition(),
+            &guard_condition->get_rcl_guard_condition(),
             nullptr);
           if (RCL_RET_OK != ret) {
-            rclcpp::exceptions::throw_from_rcl_error(ret);
+            rclcpp::exceptions::throw_from_rcl_error(ret, "Couldn't fill wait set");
           }
         }
       };
@@ -301,8 +298,7 @@ protected:
 
     // Add timers.
     for (const auto & timer : timers) {
-      auto timer_ptr_pair = get_raw_pointer_from_smart_pointer(timer);
-      if (nullptr == timer_ptr_pair.second) {
+      if (!timer) {
         // In this case it was probably stored as a weak_ptr, but is now locking to nullptr.
         if (HasStrongOwnership) {
           // This will not happen in fixed sized storage, as it holds
@@ -315,17 +311,16 @@ protected:
       }
       rcl_ret_t ret = rcl_wait_set_add_timer(
         &rcl_wait_set_,
-        timer_ptr_pair.second->get_timer_handle().get(),
+        timer->get_timer_handle().get(),
         nullptr);
       if (RCL_RET_OK != ret) {
-        rclcpp::exceptions::throw_from_rcl_error(ret);
+        rclcpp::exceptions::throw_from_rcl_error(ret, "Couldn't fill wait set");
       }
     }
 
     // Add clients.
     for (const auto & client : clients) {
-      auto client_ptr_pair = get_raw_pointer_from_smart_pointer(client);
-      if (nullptr == client_ptr_pair.second) {
+      if (!client) {
         // In this case it was probably stored as a weak_ptr, but is now locking to nullptr.
         if (HasStrongOwnership) {
           // This will not happen in fixed sized storage, as it holds
@@ -338,17 +333,17 @@ protected:
       }
       rcl_ret_t ret = rcl_wait_set_add_client(
         &rcl_wait_set_,
-        client_ptr_pair.second->get_client_handle().get(),
+        client->get_client_handle().get(),
         nullptr);
       if (RCL_RET_OK != ret) {
         rclcpp::exceptions::throw_from_rcl_error(ret);
       }
     }
 
+
     // Add services.
     for (const auto & service : services) {
-      auto service_ptr_pair = get_raw_pointer_from_smart_pointer(service);
-      if (nullptr == service_ptr_pair.second) {
+      if (!service) {
         // In this case it was probably stored as a weak_ptr, but is now locking to nullptr.
         if (HasStrongOwnership) {
           // This will not happen in fixed sized storage, as it holds
@@ -361,17 +356,16 @@ protected:
       }
       rcl_ret_t ret = rcl_wait_set_add_service(
         &rcl_wait_set_,
-        service_ptr_pair.second->get_service_handle().get(),
+        service->get_service_handle().get(),
         nullptr);
       if (RCL_RET_OK != ret) {
-        rclcpp::exceptions::throw_from_rcl_error(ret);
+        rclcpp::exceptions::throw_from_rcl_error(ret, "Couldn't fill wait set");
       }
     }
 
     // Add waitables.
     for (auto & waitable_entry : waitables) {
-      auto waitable_ptr_pair = get_raw_pointer_from_smart_pointer(waitable_entry.waitable);
-      if (nullptr == waitable_ptr_pair.second) {
+      if (!waitable_entry.waitable) {
         // In this case it was probably stored as a weak_ptr, but is now locking to nullptr.
         if (HasStrongOwnership) {
           // This will not happen in fixed sized storage, as it holds
@@ -382,8 +376,7 @@ protected:
         needs_pruning_ = true;
         continue;
       }
-      rclcpp::Waitable & waitable = *waitable_ptr_pair.second;
-      waitable.add_to_wait_set(&rcl_wait_set_);
+      waitable_entry.waitable->add_to_wait_set(&rcl_wait_set_);
     }
   }
 

rclcpp/include/rclcpp/wait_set_policies/dynamic_storage.hpp

@@ -204,15 +204,19 @@ public:
   void
   storage_rebuild_rcl_wait_set(const ArrayOfExtraGuardConditions & extra_guard_conditions)
   {
+    this->storage_acquire_ownerships();
+
     this->storage_rebuild_rcl_wait_set_with_sets(
-      subscriptions_,
-      guard_conditions_,
+      shared_subscriptions_,
+      shared_guard_conditions_,
       extra_guard_conditions,
-      timers_,
-      clients_,
-      services_,
-      waitables_
+      shared_timers_,
+      shared_clients_,
+      shared_services_,
+      shared_waitables_
     );
+
+    this->storage_release_ownerships();
   }
 
   template<class EntityT, class SequenceOfEntitiesT>
@@ -407,6 +411,7 @@ public:
         }
       };
     // Lock all the weak pointers and hold them until released.
+    lock_all(subscriptions_, shared_subscriptions_);
     lock_all(guard_conditions_, shared_guard_conditions_);
     lock_all(timers_, shared_timers_);
     lock_all(clients_, shared_clients_);
@@ -438,6 +443,7 @@ public:
           shared_ptr.reset();
         }
       };
+    reset_all(shared_subscriptions_);
     reset_all(shared_guard_conditions_);
     reset_all(shared_timers_);
     reset_all(shared_clients_);

rclcpp/include/rclcpp/wait_set_policies/sequential_synchronization.hpp

@@ -290,7 +290,7 @@ protected:
         return create_wait_result(WaitResultKind::Empty);
       } else {
         // Some other error case, throw.
-        rclcpp::exceptions::throw_from_rcl_error(ret);
+        rclcpp::exceptions::throw_from_rcl_error(ret, "rcl_wait() failed");
       }
     } while (should_loop());
 

rclcpp/package.xml

@@ -2,7 +2,7 @@
 <?xml-model href="http://download.ros.org/schema/package_format2.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
 <package format="2">
   <name>rclcpp</name>
-  <version>19.3.0</version>
+  <version>20.0.0</version>
   <description>The ROS client library in C++.</description>
 
   <maintainer email="ivanpauno@ekumenlabs.com">Ivan Paunovic</maintainer>
@@ -39,6 +39,7 @@
   <depend>rcpputils</depend>
   <depend>rcutils</depend>
   <depend>rmw</depend>
+  <depend>rosidl_dynamic_typesupport</depend>
   <depend>statistics_msgs</depend>
   <depend>tracetools</depend>
 

rclcpp/src/rclcpp/any_executable.cpp

@@ -16,13 +16,16 @@
 
 using rclcpp::AnyExecutable;
 
+RCLCPP_PUBLIC
 AnyExecutable::AnyExecutable()
 : subscription(nullptr),
   timer(nullptr),
   service(nullptr),
   client(nullptr),
+  waitable(nullptr),
   callback_group(nullptr),
-  node_base(nullptr)
+  node_base(nullptr),
+  data(nullptr)
 {}
 
 AnyExecutable::~AnyExecutable()

rclcpp/src/rclcpp/callback_group.cpp

@@ -31,10 +31,12 @@ using rclcpp::CallbackGroupType;
 
 CallbackGroup::CallbackGroup(
   CallbackGroupType group_type,
+  std::function<rclcpp::Context::SharedPtr(void)> get_context,
   bool automatically_add_to_executor_with_node)
 : type_(group_type), associated_with_executor_(false),
   can_be_taken_from_(true),
-  automatically_add_to_executor_with_node_(automatically_add_to_executor_with_node)
+  automatically_add_to_executor_with_node_(automatically_add_to_executor_with_node),
+  get_context_(get_context)
 {}
 
 CallbackGroup::~CallbackGroup()
@@ -54,6 +56,17 @@ CallbackGroup::type() const
   return type_;
 }
 
+size_t
+CallbackGroup::size() const
+{
+  return
+    subscription_ptrs_.size() +
+    service_ptrs_.size() +
+    client_ptrs_.size() +
+    timer_ptrs_.size() +
+    waitable_ptrs_.size();
+}
+
 void CallbackGroup::collect_all_ptrs(
   std::function<void(const rclcpp::SubscriptionBase::SharedPtr &)> sub_func,
   std::function<void(const rclcpp::ServiceBase::SharedPtr &)> service_func,
@@ -111,6 +124,7 @@ CallbackGroup::automatically_add_to_executor_with_node() const
   return automatically_add_to_executor_with_node_;
 }
 
+// \TODO(mjcarroll) Deprecated, remove on tock
 rclcpp::GuardCondition::SharedPtr
 CallbackGroup::get_notify_guard_condition(const rclcpp::Context::SharedPtr context_ptr)
 {
@@ -129,6 +143,29 @@ CallbackGroup::get_notify_guard_condition(const rclcpp::Context::SharedPtr conte
   return notify_guard_condition_;
 }
 
+rclcpp::GuardCondition::SharedPtr
+CallbackGroup::get_notify_guard_condition()
+{
+  std::lock_guard<std::recursive_mutex> lock(notify_guard_condition_mutex_);
+  if (!this->get_context_) {
+    throw std::runtime_error("Callback group was created without context and not passed context");
+  }
+  auto context_ptr = this->get_context_();
+  if (context_ptr && context_ptr->is_valid()) {
+    if (notify_guard_condition_ && context_ptr != notify_guard_condition_->get_context()) {
+      if (associated_with_executor_) {
+        trigger_notify_guard_condition();
+      }
+      notify_guard_condition_ = nullptr;
+    }
+    if (!notify_guard_condition_) {
+      notify_guard_condition_ = std::make_shared<rclcpp::GuardCondition>(context_ptr);
+    }
+    return notify_guard_condition_;
+  }
+  return nullptr;
+}
+
 void
 CallbackGroup::trigger_notify_guard_condition()
 {

rclcpp/src/rclcpp/dynamic_typesupport/dynamic_message.cpp

@@ -0,0 +1,40 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <rosidl_dynamic_typesupport/api/dynamic_type.h>
+#include <rosidl_dynamic_typesupport/api/dynamic_data.h>
+#include <rosidl_dynamic_typesupport/api/serialization_support.h>
+#include <rosidl_dynamic_typesupport/types.h>
+
+#include <memory>
+#include <string>
+
+#include "rcl/allocator.h"
+#include "rcl/types.h"
+#include "rcutils/logging_macros.h"
+
+#include "rclcpp/dynamic_typesupport/dynamic_message.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message_type.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message_type_builder.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp"
+#include "rclcpp/exceptions.hpp"
+
+
+using rclcpp::dynamic_typesupport::DynamicMessage;
+using rclcpp::dynamic_typesupport::DynamicMessageType;
+using rclcpp::dynamic_typesupport::DynamicMessageTypeBuilder;
+using rclcpp::dynamic_typesupport::DynamicSerializationSupport;
+
+DynamicMessage::~DynamicMessage()
+{}  // STUBBED

rclcpp/src/rclcpp/dynamic_typesupport/dynamic_message_type.cpp

@@ -0,0 +1,38 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <rosidl_dynamic_typesupport/api/dynamic_data.h>
+#include <rosidl_dynamic_typesupport/api/dynamic_type.h>
+#include <rosidl_dynamic_typesupport/api/serialization_support.h>
+#include <rosidl_dynamic_typesupport/types.h>
+
+#include <memory>
+#include <string>
+
+#include "rcutils/logging_macros.h"
+
+#include "rclcpp/dynamic_typesupport/dynamic_message.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message_type.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message_type_builder.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp"
+#include "rclcpp/exceptions.hpp"
+
+
+using rclcpp::dynamic_typesupport::DynamicMessage;
+using rclcpp::dynamic_typesupport::DynamicMessageType;
+using rclcpp::dynamic_typesupport::DynamicMessageTypeBuilder;
+using rclcpp::dynamic_typesupport::DynamicSerializationSupport;
+
+DynamicMessageType::~DynamicMessageType()
+{}  // STUBBED

rclcpp/src/rclcpp/dynamic_typesupport/dynamic_message_type_builder.cpp

@@ -0,0 +1,37 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <rosidl_dynamic_typesupport/api/dynamic_data.h>
+#include <rosidl_dynamic_typesupport/api/dynamic_type.h>
+#include <rosidl_dynamic_typesupport/api/serialization_support.h>
+#include <rosidl_dynamic_typesupport/types.h>
+
+#include <memory>
+#include <string>
+
+#include "rcutils/logging_macros.h"
+
+#include "rclcpp/dynamic_typesupport/dynamic_message.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message_type.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message_type_builder.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp"
+#include "rclcpp/exceptions.hpp"
+
+using rclcpp::dynamic_typesupport::DynamicMessage;
+using rclcpp::dynamic_typesupport::DynamicMessageType;
+using rclcpp::dynamic_typesupport::DynamicMessageTypeBuilder;
+using rclcpp::dynamic_typesupport::DynamicSerializationSupport;
+
+DynamicMessageTypeBuilder::~DynamicMessageTypeBuilder()
+{}  // STUBBED

rclcpp/src/rclcpp/dynamic_typesupport/dynamic_message_type_support.cpp

@@ -0,0 +1,49 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <rosidl_dynamic_typesupport/identifier.h>
+#include <rosidl_dynamic_typesupport/types.h>
+#include <rosidl_runtime_c/message_type_support_struct.h>
+#include <rosidl_runtime_c/type_description_utils.h>
+#include <rosidl_runtime_c/type_description/type_description__functions.h>
+#include <rosidl_runtime_c/type_description/type_description__struct.h>
+#include <rosidl_runtime_c/type_description/type_source__functions.h>
+#include <rosidl_runtime_c/type_description/type_source__struct.h>
+
+#include <memory>
+#include <string>
+
+#include "rcl/allocator.h"
+#include "rcl/dynamic_message_type_support.h"
+#include "rcl/type_hash.h"
+#include "rcl/types.h"
+#include "rcutils/logging_macros.h"
+#include "rcutils/types/rcutils_ret.h"
+#include "rmw/dynamic_message_type_support.h"
+
+#include "rclcpp/dynamic_typesupport/dynamic_message.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message_type.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_message_type_support.hpp"
+#include "rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp"
+#include "rclcpp/exceptions.hpp"
+#include "rclcpp/macros.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+using rclcpp::dynamic_typesupport::DynamicMessage;
+using rclcpp::dynamic_typesupport::DynamicMessageType;
+using rclcpp::dynamic_typesupport::DynamicMessageTypeSupport;
+using rclcpp::dynamic_typesupport::DynamicSerializationSupport;
+
+DynamicMessageTypeSupport::~DynamicMessageTypeSupport()
+{}  // STUBBED

rclcpp/src/rclcpp/dynamic_typesupport/dynamic_serialization_support.cpp

@@ -0,0 +1,46 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <rcl/allocator.h>
+#include <rcutils/logging_macros.h>
+#include <rmw/dynamic_message_type_support.h>
+#include <rmw/ret_types.h>
+#include <rosidl_dynamic_typesupport/api/serialization_support.h>
+
+#include <memory>
+#include <string>
+
+#include "rclcpp/dynamic_typesupport/dynamic_serialization_support.hpp"
+#include "rclcpp/exceptions.hpp"
+
+using rclcpp::dynamic_typesupport::DynamicSerializationSupport;
+
+// CONSTRUCTION ====================================================================================
+DynamicSerializationSupport::DynamicSerializationSupport(rcl_allocator_t allocator)
+: DynamicSerializationSupport::DynamicSerializationSupport("", allocator)
+{
+  throw std::runtime_error("Unimplemented");
+}
+
+DynamicSerializationSupport::DynamicSerializationSupport(
+  const std::string & /*serialization_library_name*/,
+  rcl_allocator_t /*allocator*/)
+: rosidl_serialization_support_(
+    rosidl_dynamic_typesupport_get_zero_initialized_serialization_support())
+{
+  throw std::runtime_error("Unimplemented");
+}
+
+DynamicSerializationSupport::~DynamicSerializationSupport()
+{}  // STUBBED

rclcpp/src/rclcpp/executors/executor_entities_collection.cpp

@@ -0,0 +1,228 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "rclcpp/executors/executor_entities_collection.hpp"
+
+namespace rclcpp
+{
+namespace executors
+{
+bool ExecutorEntitiesCollection::empty() const
+{
+  return
+    subscriptions.empty() &&
+    timers.empty() &&
+    guard_conditions.empty() &&
+    clients.empty() &&
+    services.empty() &&
+    waitables.empty();
+}
+
+void ExecutorEntitiesCollection::clear()
+{
+  subscriptions.clear();
+  timers.clear();
+  guard_conditions.clear();
+  clients.clear();
+  services.clear();
+  waitables.clear();
+}
+
+void
+build_entities_collection(
+  const std::vector<rclcpp::CallbackGroup::WeakPtr> & callback_groups,
+  ExecutorEntitiesCollection & collection)
+{
+  collection.clear();
+
+  for (auto weak_group_ptr : callback_groups) {
+    auto group_ptr = weak_group_ptr.lock();
+    if (!group_ptr) {
+      continue;
+    }
+
+    if (group_ptr->can_be_taken_from().load()) {
+      group_ptr->collect_all_ptrs(
+        [&collection, weak_group_ptr](const rclcpp::SubscriptionBase::SharedPtr & subscription) {
+          collection.subscriptions.insert(
+            {
+              subscription->get_subscription_handle().get(),
+              {subscription, weak_group_ptr}
+            });
+        },
+        [&collection, weak_group_ptr](const rclcpp::ServiceBase::SharedPtr & service) {
+          collection.services.insert(
+            {
+              service->get_service_handle().get(),
+              {service, weak_group_ptr}
+            });
+        },
+        [&collection, weak_group_ptr](const rclcpp::ClientBase::SharedPtr & client) {
+          collection.clients.insert(
+            {
+              client->get_client_handle().get(),
+              {client, weak_group_ptr}
+            });
+        },
+        [&collection, weak_group_ptr](const rclcpp::TimerBase::SharedPtr & timer) {
+          collection.timers.insert(
+            {
+              timer->get_timer_handle().get(),
+              {timer, weak_group_ptr}
+            });
+        },
+        [&collection, weak_group_ptr](const rclcpp::Waitable::SharedPtr & waitable) {
+          collection.waitables.insert(
+            {
+              waitable.get(),
+              {waitable, weak_group_ptr}
+            });
+        }
+      );
+    }
+  }
+}
+
+size_t
+ready_executables(
+  const ExecutorEntitiesCollection & collection,
+  rclcpp::WaitResult<rclcpp::WaitSet> & wait_result,
+  std::deque<rclcpp::AnyExecutable> & executables
+)
+{
+  size_t added = 0;
+  if (wait_result.kind() != rclcpp::WaitResultKind::Ready) {
+    return added;
+  }
+  auto rcl_wait_set = wait_result.get_wait_set().get_rcl_wait_set();
+
+  // Cache shared pointers to groups to avoid extra work re-locking them
+  std::map<rclcpp::CallbackGroup::WeakPtr,
+    rclcpp::CallbackGroup::SharedPtr,
+    std::owner_less<rclcpp::CallbackGroup::WeakPtr>> group_map;
+
+  auto group_cache = [&group_map](const rclcpp::CallbackGroup::WeakPtr & weak_cbg_ptr)
+    {
+      if (group_map.count(weak_cbg_ptr) == 0) {
+        group_map.insert({weak_cbg_ptr, weak_cbg_ptr.lock()});
+      }
+      return group_map.find(weak_cbg_ptr)->second;
+    };
+
+  for (size_t ii = 0; ii < rcl_wait_set.size_of_timers; ++ii) {
+    if (nullptr == rcl_wait_set.timers[ii]) {continue;}
+    auto entity_iter = collection.timers.find(rcl_wait_set.timers[ii]);
+    if (entity_iter != collection.timers.end()) {
+      auto entity = entity_iter->second.entity.lock();
+      if (!entity) {
+        continue;
+      }
+      auto group_info = group_cache(entity_iter->second.callback_group);
+      if (group_info && !group_info->can_be_taken_from().load()) {
+        continue;
+      }
+      if (!entity->call()) {
+        continue;
+      }
+      rclcpp::AnyExecutable exec;
+      exec.timer = entity;
+      exec.callback_group = group_info;
+      executables.push_back(exec);
+      added++;
+    }
+  }
+
+  for (size_t ii = 0; ii < rcl_wait_set.size_of_subscriptions; ++ii) {
+    if (nullptr == rcl_wait_set.subscriptions[ii]) {continue;}
+    auto entity_iter = collection.subscriptions.find(rcl_wait_set.subscriptions[ii]);
+    if (entity_iter != collection.subscriptions.end()) {
+      auto entity = entity_iter->second.entity.lock();
+      if (!entity) {
+        continue;
+      }
+      auto group_info = group_cache(entity_iter->second.callback_group);
+      if (group_info && !group_info->can_be_taken_from().load()) {
+        continue;
+      }
+      rclcpp::AnyExecutable exec;
+      exec.subscription = entity;
+      exec.callback_group = group_info;
+      executables.push_back(exec);
+      added++;
+    }
+  }
+
+  for (size_t ii = 0; ii < rcl_wait_set.size_of_services; ++ii) {
+    if (nullptr == rcl_wait_set.services[ii]) {continue;}
+    auto entity_iter = collection.services.find(rcl_wait_set.services[ii]);
+    if (entity_iter != collection.services.end()) {
+      auto entity = entity_iter->second.entity.lock();
+      if (!entity) {
+        continue;
+      }
+      auto group_info = group_cache(entity_iter->second.callback_group);
+      if (group_info && !group_info->can_be_taken_from().load()) {
+        continue;
+      }
+      rclcpp::AnyExecutable exec;
+      exec.service = entity;
+      exec.callback_group = group_info;
+      executables.push_back(exec);
+      added++;
+    }
+  }
+
+  for (size_t ii = 0; ii < rcl_wait_set.size_of_clients; ++ii) {
+    if (nullptr == rcl_wait_set.clients[ii]) {continue;}
+    auto entity_iter = collection.clients.find(rcl_wait_set.clients[ii]);
+    if (entity_iter != collection.clients.end()) {
+      auto entity = entity_iter->second.entity.lock();
+      if (!entity) {
+        continue;
+      }
+      auto group_info = group_cache(entity_iter->second.callback_group);
+      if (group_info && !group_info->can_be_taken_from().load()) {
+        continue;
+      }
+      rclcpp::AnyExecutable exec;
+      exec.client = entity;
+      exec.callback_group = group_info;
+      executables.push_back(exec);
+      added++;
+    }
+  }
+
+  for (auto & [handle, entry] : collection.waitables) {
+    auto waitable = entry.entity.lock();
+    if (!waitable) {
+      continue;
+    }
+    if (!waitable->is_ready(&rcl_wait_set)) {
+      continue;
+    }
+    auto group_info = group_cache(entry.callback_group);
+    if (group_info && !group_info->can_be_taken_from().load()) {
+      continue;
+    }
+    rclcpp::AnyExecutable exec;
+    exec.waitable = waitable;
+    exec.callback_group = group_info;
+    exec.data = waitable->take_data();
+    executables.push_back(exec);
+    added++;
+  }
+  return added;
+}
+}  // namespace executors
+}  // namespace rclcpp

rclcpp/src/rclcpp/executors/executor_entities_collector.cpp

@@ -0,0 +1,420 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <set>
+
+#include "rclcpp/executors/executor_entities_collector.hpp"
+#include "rclcpp/executors/executor_notify_waitable.hpp"
+#include "rclcpp/node_interfaces/node_base_interface.hpp"
+
+namespace rclcpp
+{
+namespace executors
+{
+
+ExecutorEntitiesCollector::ExecutorEntitiesCollector(
+  std::shared_ptr<ExecutorNotifyWaitable> notify_waitable)
+: notify_waitable_(notify_waitable)
+{
+}
+
+ExecutorEntitiesCollector::~ExecutorEntitiesCollector()
+{
+  for (auto weak_node_it = weak_nodes_.begin(); weak_node_it != weak_nodes_.end(); ) {
+    weak_node_it = remove_weak_node(weak_node_it);
+  }
+
+  for (auto weak_group_it = automatically_added_groups_.begin();
+    weak_group_it != automatically_added_groups_.end(); )
+  {
+    weak_group_it = remove_weak_callback_group(weak_group_it, automatically_added_groups_);
+  }
+
+  for (auto weak_group_it = manually_added_groups_.begin();
+    weak_group_it != manually_added_groups_.end(); )
+  {
+    weak_group_it = remove_weak_callback_group(weak_group_it, manually_added_groups_);
+  }
+
+  for (auto weak_node_ptr : pending_added_nodes_) {
+    auto node_ptr = weak_node_ptr.lock();
+    if (node_ptr) {
+      node_ptr->get_associated_with_executor_atomic().store(false);
+    }
+  }
+  pending_added_nodes_.clear();
+  pending_removed_nodes_.clear();
+
+  for (auto weak_group_ptr : pending_manually_added_groups_) {
+    auto group_ptr = weak_group_ptr.lock();
+    if (group_ptr) {
+      group_ptr->get_associated_with_executor_atomic().store(false);
+    }
+  }
+  pending_manually_added_groups_.clear();
+  pending_manually_removed_groups_.clear();
+}
+
+bool
+ExecutorEntitiesCollector::has_pending() const
+{
+  std::lock_guard<std::mutex> lock(mutex_);
+  return pending_manually_added_groups_.size() != 0 ||
+         pending_manually_removed_groups_.size() != 0 ||
+         pending_added_nodes_.size() != 0 ||
+         pending_removed_nodes_.size() != 0;
+}
+
+void
+ExecutorEntitiesCollector::add_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr)
+{
+  // If the node already has an executor
+  std::atomic_bool & has_executor = node_ptr->get_associated_with_executor_atomic();
+  if (has_executor.exchange(true)) {
+    throw std::runtime_error(
+            std::string("Node '") + node_ptr->get_fully_qualified_name() +
+            "' has already been added to an executor.");
+  }
+
+  std::lock_guard<std::mutex> lock(mutex_);
+  bool associated = weak_nodes_.count(node_ptr) != 0;
+  bool add_queued = pending_added_nodes_.count(node_ptr) != 0;
+  bool remove_queued = pending_removed_nodes_.count(node_ptr) != 0;
+
+  if ((associated || add_queued) && !remove_queued) {
+    throw std::runtime_error(
+            std::string("Node '") + node_ptr->get_fully_qualified_name() +
+            "' has already been added to this executor.");
+  }
+
+  this->pending_added_nodes_.insert(node_ptr);
+}
+
+void
+ExecutorEntitiesCollector::remove_node(
+  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr)
+{
+  std::atomic_bool & has_executor = node_ptr->get_associated_with_executor_atomic();
+  if (!has_executor.exchange(false)) {
+    throw std::runtime_error(
+            std::string("Node '") + node_ptr->get_fully_qualified_name() +
+            "' needs to be associated with an executor.");
+  }
+
+  std::lock_guard<std::mutex> lock(mutex_);
+  bool associated = weak_nodes_.count(node_ptr) != 0;
+  bool add_queued = pending_added_nodes_.count(node_ptr) != 0;
+  bool remove_queued = pending_removed_nodes_.count(node_ptr) != 0;
+
+  if (!(associated || add_queued) || remove_queued) {
+    throw std::runtime_error(
+            std::string("Node '") + node_ptr->get_fully_qualified_name() +
+            "' needs to be associated with this executor.");
+  }
+
+  this->pending_removed_nodes_.insert(node_ptr);
+}
+
+void
+ExecutorEntitiesCollector::add_callback_group(rclcpp::CallbackGroup::SharedPtr group_ptr)
+{
+  std::atomic_bool & has_executor = group_ptr->get_associated_with_executor_atomic();
+  if (has_executor.exchange(true)) {
+    throw std::runtime_error("Callback group has already been added to an executor.");
+  }
+
+  std::lock_guard<std::mutex> lock(mutex_);
+  bool associated = manually_added_groups_.count(group_ptr) != 0;
+  bool add_queued = pending_manually_added_groups_.count(group_ptr) != 0;
+  bool remove_queued = pending_manually_removed_groups_.count(group_ptr) != 0;
+
+  if ((associated || add_queued) && !remove_queued) {
+    throw std::runtime_error("Callback group has already been added to this executor.");
+  }
+
+  this->pending_manually_added_groups_.insert(group_ptr);
+}
+
+void
+ExecutorEntitiesCollector::remove_callback_group(rclcpp::CallbackGroup::SharedPtr group_ptr)
+{
+  if (!group_ptr->get_associated_with_executor_atomic().load()) {
+    throw std::runtime_error("Callback group needs to be associated with an executor.");
+  }
+  /**
+   * TODO(mjcarroll): The callback groups, being created by a node, should never outlive
+   * the node. Since we haven't historically enforced this, turning this on may cause
+   * previously-functional code to fail.
+   * Consider re-enablng this check (along with corresponding CallbackGroup::has_valid_node),
+   * when we can guarantee node/group lifetimes.
+  if (!group_ptr->has_valid_node()) {
+    throw std::runtime_error("Node must not be deleted before its callback group(s).");
+  }
+  */
+  auto weak_group_ptr = rclcpp::CallbackGroup::WeakPtr(group_ptr);
+  std::lock_guard<std::mutex> lock(mutex_);
+  bool associated = manually_added_groups_.count(group_ptr) != 0;
+  bool add_queued = pending_manually_added_groups_.count(group_ptr) != 0;
+  bool remove_queued = pending_manually_removed_groups_.count(group_ptr) != 0;
+
+  if (!(associated || add_queued) || remove_queued) {
+    throw std::runtime_error("Callback group needs to be associated with this executor.");
+  }
+
+  this->pending_manually_removed_groups_.insert(group_ptr);
+}
+
+std::vector<rclcpp::CallbackGroup::WeakPtr>
+ExecutorEntitiesCollector::get_all_callback_groups() const
+{
+  std::vector<rclcpp::CallbackGroup::WeakPtr> groups;
+  std::lock_guard<std::mutex> lock(mutex_);
+  for (const auto & group_ptr : manually_added_groups_) {
+    groups.push_back(group_ptr);
+  }
+  for (auto const & group_ptr : automatically_added_groups_) {
+    groups.push_back(group_ptr);
+  }
+  return groups;
+}
+
+std::vector<rclcpp::CallbackGroup::WeakPtr>
+ExecutorEntitiesCollector::get_manually_added_callback_groups() const
+{
+  std::vector<rclcpp::CallbackGroup::WeakPtr> groups;
+  std::lock_guard<std::mutex> lock(mutex_);
+  for (const auto & group_ptr : manually_added_groups_) {
+    groups.push_back(group_ptr);
+  }
+  return groups;
+}
+
+std::vector<rclcpp::CallbackGroup::WeakPtr>
+ExecutorEntitiesCollector::get_automatically_added_callback_groups() const
+{
+  std::vector<rclcpp::CallbackGroup::WeakPtr> groups;
+  std::lock_guard<std::mutex> lock(mutex_);
+  for (auto const & group_ptr : automatically_added_groups_) {
+    groups.push_back(group_ptr);
+  }
+  return groups;
+}
+
+void
+ExecutorEntitiesCollector::update_collections()
+{
+  std::lock_guard<std::mutex> lock(mutex_);
+  this->process_queues();
+  this->add_automatically_associated_callback_groups(this->weak_nodes_);
+  this->prune_invalid_nodes_and_groups();
+}
+
+ExecutorEntitiesCollector::NodeCollection::iterator
+ExecutorEntitiesCollector::remove_weak_node(NodeCollection::iterator weak_node)
+{
+  // Disassociate the guard condition from the executor notify waitable
+  auto guard_condition_it = weak_nodes_to_guard_conditions_.find(*weak_node);
+  if (guard_condition_it != weak_nodes_to_guard_conditions_.end()) {
+    this->notify_waitable_->remove_guard_condition(guard_condition_it->second);
+    weak_nodes_to_guard_conditions_.erase(guard_condition_it);
+  }
+
+  // Mark the node as disassociated (if the node is still valid)
+  auto node_ptr = weak_node->lock();
+  if (node_ptr) {
+    std::atomic_bool & has_executor = node_ptr->get_associated_with_executor_atomic();
+    has_executor.store(false);
+  }
+
+  // Remove the node from tracked nodes
+  return weak_nodes_.erase(weak_node);
+}
+
+ExecutorEntitiesCollector::CallbackGroupCollection::iterator
+ExecutorEntitiesCollector::remove_weak_callback_group(
+  CallbackGroupCollection::iterator weak_group_it,
+  CallbackGroupCollection & collection
+)
+{
+  // Disassociate the guard condition from the executor notify waitable
+  auto guard_condition_it = weak_groups_to_guard_conditions_.find(*weak_group_it);
+  if (guard_condition_it != weak_groups_to_guard_conditions_.end()) {
+    this->notify_waitable_->remove_guard_condition(guard_condition_it->second);
+    weak_groups_to_guard_conditions_.erase(guard_condition_it);
+  }
+
+  // Mark the node as disassociated (if the group is still valid)
+  auto group_ptr = weak_group_it->lock();
+  if (group_ptr) {
+    /**
+     * TODO(mjcarroll): The callback groups, being created by a node, should never outlive
+     * the node. Since we haven't historically enforced this, turning this on may cause
+     * previously-functional code to fail.
+     * Consider re-enablng this check (along with corresponding CallbackGroup::has_valid_node),
+     * when we can guarantee node/group lifetimes.
+    if (!group_ptr->has_valid_node()) {
+      throw std::runtime_error("Node must not be deleted before its callback group(s).");
+    }
+    */
+    std::atomic_bool & has_executor = group_ptr->get_associated_with_executor_atomic();
+    has_executor.store(false);
+  }
+
+  // Remove the node from tracked nodes
+  return collection.erase(weak_group_it);
+}
+
+void
+ExecutorEntitiesCollector::add_callback_group_to_collection(
+  rclcpp::CallbackGroup::SharedPtr group_ptr,
+  CallbackGroupCollection & collection)
+{
+  auto iter = collection.insert(group_ptr);
+  if (iter.second == false) {
+    throw std::runtime_error("Callback group has already been added to this executor.");
+  }
+
+  // Store node guard condition in map and add it to the notify waitable
+  auto group_guard_condition = group_ptr->get_notify_guard_condition();
+  weak_groups_to_guard_conditions_.insert({group_ptr, group_guard_condition});
+  this->notify_waitable_->add_guard_condition(group_guard_condition);
+}
+
+void
+ExecutorEntitiesCollector::process_queues()
+{
+  for (auto weak_node_ptr : pending_added_nodes_) {
+    auto node_ptr = weak_node_ptr.lock();
+    if (!node_ptr) {
+      continue;
+    }
+    weak_nodes_.insert(weak_node_ptr);
+    this->add_automatically_associated_callback_groups({weak_node_ptr});
+
+    // Store node guard condition in map and add it to the notify waitable
+    auto node_guard_condition = node_ptr->get_shared_notify_guard_condition();
+    weak_nodes_to_guard_conditions_.insert({weak_node_ptr, node_guard_condition});
+    this->notify_waitable_->add_guard_condition(node_guard_condition);
+  }
+  pending_added_nodes_.clear();
+
+  for (auto weak_node_ptr : pending_removed_nodes_) {
+    auto node_it = weak_nodes_.find(weak_node_ptr);
+    if (node_it != weak_nodes_.end()) {
+      remove_weak_node(node_it);
+    } else {
+      // The node may have been destroyed and removed from the colletion before
+      // we processed the queues.  Don't throw if the pointer is already expired.
+      if (!weak_node_ptr.expired()) {
+        throw std::runtime_error("Node needs to be associated with this executor.");
+      }
+    }
+
+    auto node_ptr = weak_node_ptr.lock();
+    if (node_ptr) {
+      for (auto group_it = automatically_added_groups_.begin();
+        group_it != automatically_added_groups_.end(); )
+      {
+        auto group_ptr = group_it->lock();
+        if (node_ptr->callback_group_in_node(group_ptr)) {
+          group_it = remove_weak_callback_group(group_it, automatically_added_groups_);
+        } else {
+          ++group_it;
+        }
+      }
+    }
+  }
+  pending_removed_nodes_.clear();
+
+  for (auto weak_group_ptr : pending_manually_added_groups_) {
+    auto group_ptr = weak_group_ptr.lock();
+    if (group_ptr) {
+      this->add_callback_group_to_collection(group_ptr, manually_added_groups_);
+    }
+  }
+  pending_manually_added_groups_.clear();
+
+  for (auto weak_group_ptr : pending_manually_removed_groups_) {
+    auto group_ptr = weak_group_ptr.lock();
+    if (group_ptr) {
+      auto group_it = manually_added_groups_.find(group_ptr);
+      if (group_it != manually_added_groups_.end()) {
+        remove_weak_callback_group(group_it, manually_added_groups_);
+      } else {
+        throw std::runtime_error(
+                "Attempting to remove a callback group not added to this executor.");
+      }
+    }
+  }
+  pending_manually_removed_groups_.clear();
+}
+
+void
+ExecutorEntitiesCollector::add_automatically_associated_callback_groups(
+  const NodeCollection & nodes_to_check)
+{
+  for (auto & weak_node : nodes_to_check) {
+    auto node = weak_node.lock();
+    if (node) {
+      node->for_each_callback_group(
+        [this, node](rclcpp::CallbackGroup::SharedPtr group_ptr)
+        {
+          if (!group_ptr->get_associated_with_executor_atomic().load() &&
+          group_ptr->automatically_add_to_executor_with_node())
+          {
+            std::atomic_bool & has_executor = group_ptr->get_associated_with_executor_atomic();
+            if (has_executor.exchange(true)) {
+              throw std::runtime_error("Callback group has already been added to an executor.");
+            }
+            this->add_callback_group_to_collection(group_ptr, this->automatically_added_groups_);
+          }
+        });
+    }
+  }
+}
+
+void
+ExecutorEntitiesCollector::prune_invalid_nodes_and_groups()
+{
+  for (auto node_it = weak_nodes_.begin();
+    node_it != weak_nodes_.end(); )
+  {
+    if (node_it->expired()) {
+      node_it = remove_weak_node(node_it);
+    } else {
+      node_it++;
+    }
+  }
+  for (auto group_it = automatically_added_groups_.begin();
+    group_it != automatically_added_groups_.end(); )
+  {
+    if (group_it->expired()) {
+      group_it = remove_weak_callback_group(group_it, automatically_added_groups_);
+    } else {
+      group_it++;
+    }
+  }
+  for (auto group_it = manually_added_groups_.begin();
+    group_it != manually_added_groups_.end(); )
+  {
+    if (group_it->expired()) {
+      group_it = remove_weak_callback_group(group_it, manually_added_groups_);
+    } else {
+      group_it++;
+    }
+  }
+}
+
+}  // namespace executors
+}  // namespace rclcpp

rclcpp/src/rclcpp/executors/executor_notify_waitable.cpp

@@ -0,0 +1,181 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <iostream>
+
+#include "rclcpp/exceptions.hpp"
+#include "rclcpp/executors/executor_notify_waitable.hpp"
+
+namespace rclcpp
+{
+namespace executors
+{
+
+ExecutorNotifyWaitable::ExecutorNotifyWaitable(std::function<void(void)> on_execute_callback)
+: execute_callback_(on_execute_callback)
+{
+}
+
+ExecutorNotifyWaitable::ExecutorNotifyWaitable(const ExecutorNotifyWaitable & other)
+: ExecutorNotifyWaitable(other.execute_callback_)
+{
+  this->notify_guard_conditions_ = other.notify_guard_conditions_;
+}
+
+ExecutorNotifyWaitable & ExecutorNotifyWaitable::operator=(const ExecutorNotifyWaitable & other)
+{
+  if (this != &other) {
+    this->execute_callback_ = other.execute_callback_;
+    this->notify_guard_conditions_ = other.notify_guard_conditions_;
+  }
+  return *this;
+}
+
+void
+ExecutorNotifyWaitable::add_to_wait_set(rcl_wait_set_t * wait_set)
+{
+  std::lock_guard<std::mutex> lock(guard_condition_mutex_);
+  for (auto weak_guard_condition : this->notify_guard_conditions_) {
+    auto guard_condition = weak_guard_condition.lock();
+    if (!guard_condition) {continue;}
+
+    rcl_guard_condition_t * cond = &guard_condition->get_rcl_guard_condition();
+
+    rcl_ret_t ret = rcl_wait_set_add_guard_condition(
+      wait_set, cond, NULL);
+
+    if (RCL_RET_OK != ret) {
+      rclcpp::exceptions::throw_from_rcl_error(
+        ret, "failed to add guard condition to wait set");
+    }
+  }
+}
+
+bool
+ExecutorNotifyWaitable::is_ready(rcl_wait_set_t * wait_set)
+{
+  std::lock_guard<std::mutex> lock(guard_condition_mutex_);
+
+  bool any_ready = false;
+  for (size_t ii = 0; ii < wait_set->size_of_guard_conditions; ++ii) {
+    auto rcl_guard_condition = wait_set->guard_conditions[ii];
+
+    if (nullptr == rcl_guard_condition) {
+      continue;
+    }
+    for (auto weak_guard_condition : this->notify_guard_conditions_) {
+      auto guard_condition = weak_guard_condition.lock();
+      if (guard_condition && &guard_condition->get_rcl_guard_condition() == rcl_guard_condition) {
+        any_ready = true;
+      }
+    }
+  }
+  return any_ready;
+}
+
+void
+ExecutorNotifyWaitable::execute(std::shared_ptr<void> & data)
+{
+  (void) data;
+  this->execute_callback_();
+}
+
+std::shared_ptr<void>
+ExecutorNotifyWaitable::take_data()
+{
+  return nullptr;
+}
+
+std::shared_ptr<void>
+ExecutorNotifyWaitable::take_data_by_entity_id(size_t id)
+{
+  (void) id;
+  return nullptr;
+}
+
+void
+ExecutorNotifyWaitable::set_on_ready_callback(std::function<void(size_t, int)> callback)
+{
+  // The second argument of the callback could be used to identify which guard condition
+  // triggered the event.
+  // We could indicate which of the guard conditions was triggered, but the executor
+  // is already going to check that.
+  auto gc_callback = [callback](size_t count) {
+      callback(count, 0);
+    };
+
+  std::lock_guard<std::mutex> lock(guard_condition_mutex_);
+
+  on_ready_callback_ = gc_callback;
+  for (auto weak_gc : notify_guard_conditions_) {
+    auto gc = weak_gc.lock();
+    if (!gc) {
+      continue;
+    }
+    gc->set_on_trigger_callback(on_ready_callback_);
+  }
+}
+
+RCLCPP_PUBLIC
+void
+ExecutorNotifyWaitable::clear_on_ready_callback()
+{
+  std::lock_guard<std::mutex> lock(guard_condition_mutex_);
+
+  on_ready_callback_ = nullptr;
+  for (auto weak_gc : notify_guard_conditions_) {
+    auto gc = weak_gc.lock();
+    if (!gc) {
+      continue;
+    }
+    gc->set_on_trigger_callback(nullptr);
+  }
+}
+
+void
+ExecutorNotifyWaitable::add_guard_condition(rclcpp::GuardCondition::WeakPtr weak_guard_condition)
+{
+  std::lock_guard<std::mutex> lock(guard_condition_mutex_);
+  auto guard_condition = weak_guard_condition.lock();
+  if (guard_condition && notify_guard_conditions_.count(weak_guard_condition) == 0) {
+    notify_guard_conditions_.insert(weak_guard_condition);
+    if (on_ready_callback_) {
+      guard_condition->set_on_trigger_callback(on_ready_callback_);
+    }
+  }
+}
+
+void
+ExecutorNotifyWaitable::remove_guard_condition(rclcpp::GuardCondition::WeakPtr weak_guard_condition)
+{
+  std::lock_guard<std::mutex> lock(guard_condition_mutex_);
+  if (notify_guard_conditions_.count(weak_guard_condition) != 0) {
+    notify_guard_conditions_.erase(weak_guard_condition);
+    auto guard_condition = weak_guard_condition.lock();
+    // If this notify waitable doesn't have an on_ready_callback, then there's nothing to unset
+    if (guard_condition && on_ready_callback_) {
+      guard_condition->set_on_trigger_callback(nullptr);
+    }
+  }
+}
+
+size_t
+ExecutorNotifyWaitable::get_number_of_ready_guard_conditions()
+{
+  std::lock_guard<std::mutex> lock(guard_condition_mutex_);
+  return notify_guard_conditions_.size();
+}
+
+}  // namespace executors
+}  // namespace rclcpp

rclcpp/src/rclcpp/executors/multi_threaded_executor.cpp

@@ -99,6 +99,19 @@ MultiThreadedExecutor::run(size_t this_thread_number)
 
     execute_any_executable(any_exec);
 
+    if (any_exec.callback_group &&
+      any_exec.callback_group->type() == CallbackGroupType::MutuallyExclusive &&
+      any_exec.callback_group->size() > 1)
+    {
+      try {
+        interrupt_guard_condition_->trigger();
+      } catch (const rclcpp::exceptions::RCLError & ex) {
+        throw std::runtime_error(
+                std::string(
+                  "Failed to trigger guard condition on callback group change: ") + ex.what());
+      }
+    }
+
     // Clear the callback_group to prevent the AnyExecutable destructor from
     // resetting the callback group `can_be_taken_from`
     any_exec.callback_group.reset();

rclcpp/src/rclcpp/executors/static_executor_entities_collector.cpp

@@ -1,524 +0,0 @@
-// Copyright 2020 Open Source Robotics Foundation, Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#include "rclcpp/executors/static_executor_entities_collector.hpp"
-
-#include <algorithm>
-#include <memory>
-#include <stdexcept>
-#include <string>
-#include <utility>
-#include <vector>
-
-#include "rclcpp/memory_strategy.hpp"
-#include "rclcpp/executors/static_single_threaded_executor.hpp"
-#include "rclcpp/detail/add_guard_condition_to_rcl_wait_set.hpp"
-
-using rclcpp::executors::StaticExecutorEntitiesCollector;
-
-StaticExecutorEntitiesCollector::~StaticExecutorEntitiesCollector()
-{
-  // Disassociate all callback groups and thus nodes.
-  for (const auto & pair : weak_groups_associated_with_executor_to_nodes_) {
-    auto group = pair.first.lock();
-    if (group) {
-      std::atomic_bool & has_executor = group->get_associated_with_executor_atomic();
-      has_executor.store(false);
-    }
-  }
-  for (const auto & pair : weak_groups_to_nodes_associated_with_executor_) {
-    auto group = pair.first.lock();
-    if (group) {
-      std::atomic_bool & has_executor = group->get_associated_with_executor_atomic();
-      has_executor.store(false);
-    }
-  }
-  // Disassociate all nodes
-  for (const auto & weak_node : weak_nodes_) {
-    auto node = weak_node.lock();
-    if (node) {
-      std::atomic_bool & has_executor = node->get_associated_with_executor_atomic();
-      has_executor.store(false);
-    }
-  }
-  weak_groups_associated_with_executor_to_nodes_.clear();
-  weak_groups_to_nodes_associated_with_executor_.clear();
-  exec_list_.clear();
-  weak_nodes_.clear();
-  weak_nodes_to_guard_conditions_.clear();
-}
-
-void
-StaticExecutorEntitiesCollector::init(
-  rcl_wait_set_t * p_wait_set,
-  rclcpp::memory_strategy::MemoryStrategy::SharedPtr memory_strategy)
-{
-  // Empty initialize executable list
-  exec_list_ = rclcpp::experimental::ExecutableList();
-  // Get executor's wait_set_ pointer
-  p_wait_set_ = p_wait_set;
-  // Get executor's memory strategy ptr
-  if (memory_strategy == nullptr) {
-    throw std::runtime_error("Received NULL memory strategy in executor waitable.");
-  }
-  memory_strategy_ = memory_strategy;
-
-  // Get memory strategy and executable list. Prepare wait_set_
-  std::shared_ptr<void> shared_ptr;
-  execute(shared_ptr);
-
-  // The entities collector is now initialized
-  initialized_ = true;
-}
-
-void
-StaticExecutorEntitiesCollector::fini()
-{
-  memory_strategy_->clear_handles();
-  exec_list_.clear();
-}
-
-std::shared_ptr<void>
-StaticExecutorEntitiesCollector::take_data()
-{
-  return nullptr;
-}
-
-void
-StaticExecutorEntitiesCollector::execute(std::shared_ptr<void> & data)
-{
-  (void) data;
-  // Fill memory strategy with entities coming from weak_nodes_
-  fill_memory_strategy();
-  // Fill exec_list_ with entities coming from weak_nodes_ (same as memory strategy)
-  fill_executable_list();
-  // Resize the wait_set_ based on memory_strategy handles (rcl_wait_set_resize)
-  prepare_wait_set();
-  // Add new nodes guard conditions to map
-  std::lock_guard<std::mutex> guard{new_nodes_mutex_};
-  for (const auto & weak_node : new_nodes_) {
-    if (auto node_ptr = weak_node.lock()) {
-      const auto & gc = node_ptr->get_notify_guard_condition();
-      weak_nodes_to_guard_conditions_[node_ptr] = &gc;
-    }
-  }
-  new_nodes_.clear();
-}
-
-void
-StaticExecutorEntitiesCollector::fill_memory_strategy()
-{
-  memory_strategy_->clear_handles();
-  bool has_invalid_weak_groups_or_nodes =
-    memory_strategy_->collect_entities(weak_groups_to_nodes_associated_with_executor_);
-  // Clean up any invalid nodes, if they were detected
-  if (has_invalid_weak_groups_or_nodes) {
-    std::vector<rclcpp::CallbackGroup::WeakPtr> invalid_group_ptrs;
-    for (const auto & pair : weak_groups_to_nodes_associated_with_executor_) {
-      auto & weak_group_ptr = pair.first;
-      auto & weak_node_ptr = pair.second;
-      if (weak_group_ptr.expired() || weak_node_ptr.expired()) {
-        invalid_group_ptrs.push_back(weak_group_ptr);
-      }
-    }
-    std::for_each(
-      invalid_group_ptrs.begin(), invalid_group_ptrs.end(),
-      [this](rclcpp::CallbackGroup::WeakPtr group_ptr) {
-        weak_groups_to_nodes_associated_with_executor_.erase(group_ptr);
-      });
-  }
-  has_invalid_weak_groups_or_nodes =
-    memory_strategy_->collect_entities(weak_groups_associated_with_executor_to_nodes_);
-  // Clean up any invalid nodes, if they were detected
-  if (has_invalid_weak_groups_or_nodes) {
-    std::vector<rclcpp::CallbackGroup::WeakPtr> invalid_group_ptrs;
-    for (const auto & pair : weak_groups_associated_with_executor_to_nodes_) {
-      auto & weak_group_ptr = pair.first;
-      const auto & weak_node_ptr = pair.second;
-      if (weak_group_ptr.expired() || weak_node_ptr.expired()) {
-        invalid_group_ptrs.push_back(weak_group_ptr);
-      }
-    }
-    std::for_each(
-      invalid_group_ptrs.begin(), invalid_group_ptrs.end(),
-      [this](rclcpp::CallbackGroup::WeakPtr group_ptr) {
-        weak_groups_associated_with_executor_to_nodes_.erase(group_ptr);
-      });
-  }
-
-  // Add the static executor waitable to the memory strategy
-  memory_strategy_->add_waitable_handle(this->shared_from_this());
-}
-
-void
-StaticExecutorEntitiesCollector::fill_executable_list()
-{
-  exec_list_.clear();
-  add_callback_groups_from_nodes_associated_to_executor();
-  fill_executable_list_from_map(weak_groups_associated_with_executor_to_nodes_);
-  fill_executable_list_from_map(weak_groups_to_nodes_associated_with_executor_);
-  // Add the executor's waitable to the executable list
-  exec_list_.add_waitable(shared_from_this());
-}
-void
-StaticExecutorEntitiesCollector::fill_executable_list_from_map(
-  const rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap &
-  weak_groups_to_nodes)
-{
-  for (const auto & pair : weak_groups_to_nodes) {
-    auto group = pair.first.lock();
-    auto node = pair.second.lock();
-    if (!node || !group || !group->can_be_taken_from().load()) {
-      continue;
-    }
-    group->find_timer_ptrs_if(
-      [this](const rclcpp::TimerBase::SharedPtr & timer) {
-        if (timer) {
-          exec_list_.add_timer(timer);
-        }
-        return false;
-      });
-    group->find_subscription_ptrs_if(
-      [this](const rclcpp::SubscriptionBase::SharedPtr & subscription) {
-        if (subscription) {
-          exec_list_.add_subscription(subscription);
-        }
-        return false;
-      });
-    group->find_service_ptrs_if(
-      [this](const rclcpp::ServiceBase::SharedPtr & service) {
-        if (service) {
-          exec_list_.add_service(service);
-        }
-        return false;
-      });
-    group->find_client_ptrs_if(
-      [this](const rclcpp::ClientBase::SharedPtr & client) {
-        if (client) {
-          exec_list_.add_client(client);
-        }
-        return false;
-      });
-    group->find_waitable_ptrs_if(
-      [this](const rclcpp::Waitable::SharedPtr & waitable) {
-        if (waitable) {
-          exec_list_.add_waitable(waitable);
-        }
-        return false;
-      });
-  }
-}
-
-void
-StaticExecutorEntitiesCollector::prepare_wait_set()
-{
-  // clear wait set
-  if (rcl_wait_set_clear(p_wait_set_) != RCL_RET_OK) {
-    throw std::runtime_error("Couldn't clear wait set");
-  }
-
-  // The size of waitables are accounted for in size of the other entities
-  rcl_ret_t ret = rcl_wait_set_resize(
-    p_wait_set_, memory_strategy_->number_of_ready_subscriptions(),
-    memory_strategy_->number_of_guard_conditions(), memory_strategy_->number_of_ready_timers(),
-    memory_strategy_->number_of_ready_clients(), memory_strategy_->number_of_ready_services(),
-    memory_strategy_->number_of_ready_events());
-
-  if (RCL_RET_OK != ret) {
-    throw std::runtime_error(
-            std::string("Couldn't resize the wait set: ") + rcl_get_error_string().str);
-  }
-}
-
-void
-StaticExecutorEntitiesCollector::refresh_wait_set(std::chrono::nanoseconds timeout)
-{
-  // clear wait set (memset to '0' all wait_set_ entities
-  // but keeps the wait_set_ number of entities)
-  if (rcl_wait_set_clear(p_wait_set_) != RCL_RET_OK) {
-    throw std::runtime_error("Couldn't clear wait set");
-  }
-
-  if (!memory_strategy_->add_handles_to_wait_set(p_wait_set_)) {
-    throw std::runtime_error("Couldn't fill wait set");
-  }
-
-  rcl_ret_t status =
-    rcl_wait(p_wait_set_, std::chrono::duration_cast<std::chrono::nanoseconds>(timeout).count());
-
-  if (status == RCL_RET_WAIT_SET_EMPTY) {
-    RCUTILS_LOG_WARN_NAMED(
-      "rclcpp",
-      "empty wait set received in rcl_wait(). This should never happen.");
-  } else if (status != RCL_RET_OK && status != RCL_RET_TIMEOUT) {
-    using rclcpp::exceptions::throw_from_rcl_error;
-    throw_from_rcl_error(status, "rcl_wait() failed");
-  }
-}
-
-void
-StaticExecutorEntitiesCollector::add_to_wait_set(rcl_wait_set_t * wait_set)
-{
-  // Add waitable guard conditions (one for each registered node) into the wait set.
-  for (const auto & pair : weak_nodes_to_guard_conditions_) {
-    auto & gc = pair.second;
-    detail::add_guard_condition_to_rcl_wait_set(*wait_set, *gc);
-  }
-}
-
-size_t StaticExecutorEntitiesCollector::get_number_of_ready_guard_conditions()
-{
-  std::lock_guard<std::mutex> guard{new_nodes_mutex_};
-  return weak_nodes_to_guard_conditions_.size() + new_nodes_.size();
-}
-
-bool
-StaticExecutorEntitiesCollector::add_node(
-  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr)
-{
-  bool is_new_node = false;
-  // If the node already has an executor
-  std::atomic_bool & has_executor = node_ptr->get_associated_with_executor_atomic();
-  if (has_executor.exchange(true)) {
-    throw std::runtime_error("Node has already been added to an executor.");
-  }
-  node_ptr->for_each_callback_group(
-    [this, node_ptr, &is_new_node](rclcpp::CallbackGroup::SharedPtr group_ptr)
-    {
-      if (
-        !group_ptr->get_associated_with_executor_atomic().load() &&
-        group_ptr->automatically_add_to_executor_with_node())
-      {
-        is_new_node = (add_callback_group(
-          group_ptr,
-          node_ptr,
-          weak_groups_to_nodes_associated_with_executor_) ||
-        is_new_node);
-      }
-    });
-  weak_nodes_.push_back(node_ptr);
-  return is_new_node;
-}
-
-bool
-StaticExecutorEntitiesCollector::add_callback_group(
-  rclcpp::CallbackGroup::SharedPtr group_ptr,
-  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-  rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap & weak_groups_to_nodes)
-{
-  // If the callback_group already has an executor
-  std::atomic_bool & has_executor = group_ptr->get_associated_with_executor_atomic();
-  if (has_executor.exchange(true)) {
-    throw std::runtime_error("Callback group has already been added to an executor.");
-  }
-  bool is_new_node = !has_node(node_ptr, weak_groups_associated_with_executor_to_nodes_) &&
-    !has_node(node_ptr, weak_groups_to_nodes_associated_with_executor_);
-  rclcpp::CallbackGroup::WeakPtr weak_group_ptr = group_ptr;
-  auto insert_info = weak_groups_to_nodes.insert(
-    std::make_pair(weak_group_ptr, node_ptr));
-  bool was_inserted = insert_info.second;
-  if (!was_inserted) {
-    throw std::runtime_error("Callback group was already added to executor.");
-  }
-  if (is_new_node) {
-    std::lock_guard<std::mutex> guard{new_nodes_mutex_};
-    new_nodes_.push_back(node_ptr);
-    return true;
-  }
-  return false;
-}
-
-bool
-StaticExecutorEntitiesCollector::add_callback_group(
-  rclcpp::CallbackGroup::SharedPtr group_ptr,
-  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr)
-{
-  return add_callback_group(group_ptr, node_ptr, weak_groups_associated_with_executor_to_nodes_);
-}
-
-bool
-StaticExecutorEntitiesCollector::remove_callback_group(
-  rclcpp::CallbackGroup::SharedPtr group_ptr)
-{
-  return this->remove_callback_group_from_map(
-    group_ptr,
-    weak_groups_associated_with_executor_to_nodes_);
-}
-
-bool
-StaticExecutorEntitiesCollector::remove_callback_group_from_map(
-  rclcpp::CallbackGroup::SharedPtr group_ptr,
-  rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap & weak_groups_to_nodes)
-{
-  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr;
-  rclcpp::CallbackGroup::WeakPtr weak_group_ptr = group_ptr;
-  auto iter = weak_groups_to_nodes.find(weak_group_ptr);
-  if (iter != weak_groups_to_nodes.end()) {
-    node_ptr = iter->second.lock();
-    if (node_ptr == nullptr) {
-      throw std::runtime_error("Node must not be deleted before its callback group(s).");
-    }
-    weak_groups_to_nodes.erase(iter);
-  } else {
-    throw std::runtime_error("Callback group needs to be associated with executor.");
-  }
-  // If the node was matched and removed, interrupt waiting.
-  if (!has_node(node_ptr, weak_groups_associated_with_executor_to_nodes_) &&
-    !has_node(node_ptr, weak_groups_to_nodes_associated_with_executor_))
-  {
-    rclcpp::node_interfaces::NodeBaseInterface::WeakPtr node_weak_ptr(node_ptr);
-    weak_nodes_to_guard_conditions_.erase(node_weak_ptr);
-    return true;
-  }
-  return false;
-}
-
-bool
-StaticExecutorEntitiesCollector::remove_node(
-  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr)
-{
-  if (!node_ptr->get_associated_with_executor_atomic().load()) {
-    return false;
-  }
-  bool node_found = false;
-  auto node_it = weak_nodes_.begin();
-  while (node_it != weak_nodes_.end()) {
-    bool matched = (node_it->lock() == node_ptr);
-    if (matched) {
-      weak_nodes_.erase(node_it);
-      node_found = true;
-      break;
-    }
-    ++node_it;
-  }
-  if (!node_found) {
-    return false;
-  }
-  std::vector<rclcpp::CallbackGroup::SharedPtr> found_group_ptrs;
-  std::for_each(
-    weak_groups_to_nodes_associated_with_executor_.begin(),
-    weak_groups_to_nodes_associated_with_executor_.end(),
-    [&found_group_ptrs, node_ptr](std::pair<rclcpp::CallbackGroup::WeakPtr,
-    rclcpp::node_interfaces::NodeBaseInterface::WeakPtr> key_value_pair) {
-      auto & weak_node_ptr = key_value_pair.second;
-      auto shared_node_ptr = weak_node_ptr.lock();
-      auto group_ptr = key_value_pair.first.lock();
-      if (shared_node_ptr == node_ptr) {
-        found_group_ptrs.push_back(group_ptr);
-      }
-    });
-  std::for_each(
-    found_group_ptrs.begin(), found_group_ptrs.end(), [this]
-      (rclcpp::CallbackGroup::SharedPtr group_ptr) {
-      this->remove_callback_group_from_map(
-        group_ptr,
-        weak_groups_to_nodes_associated_with_executor_);
-    });
-  std::atomic_bool & has_executor = node_ptr->get_associated_with_executor_atomic();
-  has_executor.store(false);
-  return true;
-}
-
-bool
-StaticExecutorEntitiesCollector::is_ready(rcl_wait_set_t * p_wait_set)
-{
-  // Check wait_set guard_conditions for added/removed entities to/from a node
-  for (size_t i = 0; i < p_wait_set->size_of_guard_conditions; ++i) {
-    if (p_wait_set->guard_conditions[i] != NULL) {
-      auto found_guard_condition = std::find_if(
-        weak_nodes_to_guard_conditions_.begin(), weak_nodes_to_guard_conditions_.end(),
-        [&](std::pair<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr,
-        const GuardCondition *> pair) -> bool {
-          const rcl_guard_condition_t & rcl_gc = pair.second->get_rcl_guard_condition();
-          return &rcl_gc == p_wait_set->guard_conditions[i];
-        });
-      if (found_guard_condition != weak_nodes_to_guard_conditions_.end()) {
-        return true;
-      }
-    }
-  }
-  // None of the guard conditions triggered belong to a registered node
-  return false;
-}
-
-// Returns true iff the weak_groups_to_nodes map has node_ptr as the value in any of its entry.
-bool
-StaticExecutorEntitiesCollector::has_node(
-  const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-  const rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap &
-  weak_groups_to_nodes) const
-{
-  return std::find_if(
-    weak_groups_to_nodes.begin(),
-    weak_groups_to_nodes.end(),
-    [&](const WeakCallbackGroupsToNodesMap::value_type & other) -> bool {
-      auto other_ptr = other.second.lock();
-      return other_ptr == node_ptr;
-    }) != weak_groups_to_nodes.end();
-}
-
-void
-StaticExecutorEntitiesCollector::add_callback_groups_from_nodes_associated_to_executor()
-{
-  for (const auto & weak_node : weak_nodes_) {
-    auto node = weak_node.lock();
-    if (node) {
-      node->for_each_callback_group(
-        [this, node](rclcpp::CallbackGroup::SharedPtr shared_group_ptr)
-        {
-          if (shared_group_ptr->automatically_add_to_executor_with_node() &&
-          !shared_group_ptr->get_associated_with_executor_atomic().load())
-          {
-            add_callback_group(
-              shared_group_ptr,
-              node,
-              weak_groups_to_nodes_associated_with_executor_);
-          }
-        });
-    }
-  }
-}
-
-std::vector<rclcpp::CallbackGroup::WeakPtr>
-StaticExecutorEntitiesCollector::get_all_callback_groups()
-{
-  std::vector<rclcpp::CallbackGroup::WeakPtr> groups;
-  for (const auto & group_node_ptr : weak_groups_associated_with_executor_to_nodes_) {
-    groups.push_back(group_node_ptr.first);
-  }
-  for (const auto & group_node_ptr : weak_groups_to_nodes_associated_with_executor_) {
-    groups.push_back(group_node_ptr.first);
-  }
-  return groups;
-}
-
-std::vector<rclcpp::CallbackGroup::WeakPtr>
-StaticExecutorEntitiesCollector::get_manually_added_callback_groups()
-{
-  std::vector<rclcpp::CallbackGroup::WeakPtr> groups;
-  for (const auto & group_node_ptr : weak_groups_associated_with_executor_to_nodes_) {
-    groups.push_back(group_node_ptr.first);
-  }
-  return groups;
-}
-
-std::vector<rclcpp::CallbackGroup::WeakPtr>
-StaticExecutorEntitiesCollector::get_automatically_added_callback_groups_from_nodes()
-{
-  std::vector<rclcpp::CallbackGroup::WeakPtr> groups;
-  for (const auto & group_node_ptr : weak_groups_to_nodes_associated_with_executor_) {
-    groups.push_back(group_node_ptr.first);
-  }
-  return groups;
-}

rclcpp/src/rclcpp/executors/static_single_threaded_executor.cpp

@@ -12,31 +12,21 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "rclcpp/executors/static_single_threaded_executor.hpp"
-
-#include <chrono>
-#include <memory>
-#include <utility>
-#include <vector>
-
+#include "rclcpp/executors/executor_entities_collection.hpp"
+#include "rclcpp/executors/executor_notify_waitable.hpp"
 #include "rcpputils/scope_exit.hpp"
 
-using rclcpp::executors::StaticSingleThreadedExecutor;
-using rclcpp::experimental::ExecutableList;
+#include "rclcpp/executors/static_single_threaded_executor.hpp"
+#include "rclcpp/any_executable.hpp"
 
-StaticSingleThreadedExecutor::StaticSingleThreadedExecutor(
-  const rclcpp::ExecutorOptions & options)
+using rclcpp::executors::StaticSingleThreadedExecutor;
+
+StaticSingleThreadedExecutor::StaticSingleThreadedExecutor(const rclcpp::ExecutorOptions & options)
 : rclcpp::Executor(options)
 {
-  entities_collector_ = std::make_shared<StaticExecutorEntitiesCollector>();
 }
 
-StaticSingleThreadedExecutor::~StaticSingleThreadedExecutor()
-{
-  if (entities_collector_->is_init()) {
-    entities_collector_->fini();
-  }
-}
+StaticSingleThreadedExecutor::~StaticSingleThreadedExecutor() {}
 
 void
 StaticSingleThreadedExecutor::spin()
@@ -46,14 +36,25 @@ StaticSingleThreadedExecutor::spin()
   }
   RCPPUTILS_SCOPE_EXIT(this->spinning.store(false); );
 
-  // Set memory_strategy_ and exec_list_ based on weak_nodes_
-  // Prepare wait_set_ based on memory_strategy_
-  entities_collector_->init(&wait_set_, memory_strategy_);
-
+  // This is essentially the contents of the rclcpp::Executor::wait_for_work method,
+  // except we need to keep the wait result to reproduce the StaticSingleThreadedExecutor
+  // behavior.
   while (rclcpp::ok(this->context_) && spinning.load()) {
-    // Refresh wait set and wait for work
-    entities_collector_->refresh_wait_set();
-    execute_ready_executables();
+    std::deque<rclcpp::AnyExecutable> to_exec;
+
+    std::lock_guard<std::mutex> guard(mutex_);
+    if (current_collection_.empty() || this->entities_need_rebuild_.load()) {
+      this->collect_entities();
+    }
+
+    auto wait_result = wait_set_.wait(std::chrono::nanoseconds(-1));
+    if (wait_result.kind() == WaitResultKind::Empty) {
+      RCUTILS_LOG_WARN_NAMED(
+        "rclcpp",
+        "empty wait set received in wait(). This should never happen.");
+      continue;
+    }
+    execute_ready_executables(current_collection_, wait_result, false);
   }
 }
 
@@ -80,11 +81,6 @@ StaticSingleThreadedExecutor::spin_all(std::chrono::nanoseconds max_duration)
 void
 StaticSingleThreadedExecutor::spin_some_impl(std::chrono::nanoseconds max_duration, bool exhaustive)
 {
-  // Make sure the entities collector has been initialized
-  if (!entities_collector_->is_init()) {
-    entities_collector_->init(&wait_set_, memory_strategy_);
-  }
-
   auto start = std::chrono::steady_clock::now();
   auto max_duration_not_elapsed = [max_duration, start]() {
       if (std::chrono::nanoseconds(0) == max_duration) {
@@ -105,9 +101,21 @@ StaticSingleThreadedExecutor::spin_some_impl(std::chrono::nanoseconds max_durati
 
   while (rclcpp::ok(context_) && spinning.load() && max_duration_not_elapsed()) {
     // Get executables that are ready now
-    entities_collector_->refresh_wait_set(std::chrono::milliseconds::zero());
+    std::lock_guard<std::mutex> guard(mutex_);
+    if (current_collection_.empty() || this->entities_need_rebuild_.load()) {
+      this->collect_entities();
+    }
+
+    auto wait_result = wait_set_.wait(std::chrono::nanoseconds(0));
+    if (wait_result.kind() == WaitResultKind::Empty) {
+      RCUTILS_LOG_WARN_NAMED(
+        "rclcpp",
+        "empty wait set received in wait(). This should never happen.");
+      continue;
+    }
+
     // Execute ready executables
-    bool work_available = execute_ready_executables();
+    bool work_available = execute_ready_executables(current_collection_, wait_result, false);
     if (!work_available || !exhaustive) {
       break;
     }
@@ -117,164 +125,122 @@ StaticSingleThreadedExecutor::spin_some_impl(std::chrono::nanoseconds max_durati
 void
 StaticSingleThreadedExecutor::spin_once_impl(std::chrono::nanoseconds timeout)
 {
-  // Make sure the entities collector has been initialized
-  if (!entities_collector_->is_init()) {
-    entities_collector_->init(&wait_set_, memory_strategy_);
-  }
-
   if (rclcpp::ok(context_) && spinning.load()) {
-    // Wait until we have a ready entity or timeout expired
-    entities_collector_->refresh_wait_set(timeout);
+    std::lock_guard<std::mutex> guard(mutex_);
+    if (current_collection_.empty() || this->entities_need_rebuild_.load()) {
+      this->collect_entities();
+    }
+
+    auto wait_result = wait_set_.wait(std::chrono::nanoseconds(timeout));
+    if (wait_result.kind() == WaitResultKind::Empty) {
+      RCUTILS_LOG_WARN_NAMED(
+        "rclcpp",
+        "empty wait set received in wait(). This should never happen.");
+      return;
+    }
+
     // Execute ready executables
-    execute_ready_executables(true);
+    execute_ready_executables(current_collection_, wait_result, true);
   }
 }
 
-void
-StaticSingleThreadedExecutor::add_callback_group(
-  rclcpp::CallbackGroup::SharedPtr group_ptr,
-  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-  bool notify)
-{
-  bool is_new_node = entities_collector_->add_callback_group(group_ptr, node_ptr);
-  if (is_new_node && notify) {
-    // Interrupt waiting to handle new node
-    interrupt_guard_condition_.trigger();
-  }
-}
-
-void
-StaticSingleThreadedExecutor::add_node(
-  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr, bool notify)
-{
-  bool is_new_node = entities_collector_->add_node(node_ptr);
-  if (is_new_node && notify) {
-    // Interrupt waiting to handle new node
-    interrupt_guard_condition_.trigger();
-  }
-}
-
-void
-StaticSingleThreadedExecutor::add_node(std::shared_ptr<rclcpp::Node> node_ptr, bool notify)
-{
-  this->add_node(node_ptr->get_node_base_interface(), notify);
-}
-
-void
-StaticSingleThreadedExecutor::remove_callback_group(
-  rclcpp::CallbackGroup::SharedPtr group_ptr, bool notify)
-{
-  bool node_removed = entities_collector_->remove_callback_group(group_ptr);
-  // If the node was matched and removed, interrupt waiting
-  if (node_removed && notify) {
-    interrupt_guard_condition_.trigger();
-  }
-}
-
-void
-StaticSingleThreadedExecutor::remove_node(
-  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr, bool notify)
-{
-  bool node_removed = entities_collector_->remove_node(node_ptr);
-  if (!node_removed) {
-    throw std::runtime_error("Node needs to be associated with this executor.");
-  }
-  // If the node was matched and removed, interrupt waiting
-  if (notify) {
-    interrupt_guard_condition_.trigger();
-  }
-}
-
-std::vector<rclcpp::CallbackGroup::WeakPtr>
-StaticSingleThreadedExecutor::get_all_callback_groups()
-{
-  return entities_collector_->get_all_callback_groups();
-}
-
-std::vector<rclcpp::CallbackGroup::WeakPtr>
-StaticSingleThreadedExecutor::get_manually_added_callback_groups()
-{
-  return entities_collector_->get_manually_added_callback_groups();
-}
-
-std::vector<rclcpp::CallbackGroup::WeakPtr>
-StaticSingleThreadedExecutor::get_automatically_added_callback_groups_from_nodes()
-{
-  return entities_collector_->get_automatically_added_callback_groups_from_nodes();
-}
-
-void
-StaticSingleThreadedExecutor::remove_node(std::shared_ptr<rclcpp::Node> node_ptr, bool notify)
-{
-  this->remove_node(node_ptr->get_node_base_interface(), notify);
-}
-
-bool
-StaticSingleThreadedExecutor::execute_ready_executables(bool spin_once)
+// This preserves the "scheduling semantics" of the StaticSingleThreadedExecutor
+// from the original implementation.
+bool StaticSingleThreadedExecutor::execute_ready_executables(
+  const rclcpp::executors::ExecutorEntitiesCollection & collection,
+  rclcpp::WaitResult<rclcpp::WaitSet> & wait_result,
+  bool spin_once)
 {
   bool any_ready_executable = false;
 
-  // Execute all the ready subscriptions
-  for (size_t i = 0; i < wait_set_.size_of_subscriptions; ++i) {
-    if (i < entities_collector_->get_number_of_subscriptions()) {
-      if (wait_set_.subscriptions[i]) {
-        execute_subscription(entities_collector_->get_subscription(i));
-        if (spin_once) {
-          return true;
-        }
-        any_ready_executable = true;
-      }
-    }
+  if (wait_result.kind() != rclcpp::WaitResultKind::Ready) {
+    return any_ready_executable;
   }
-  // Execute all the ready timers
-  for (size_t i = 0; i < wait_set_.size_of_timers; ++i) {
-    if (i < entities_collector_->get_number_of_timers()) {
-      if (wait_set_.timers[i] && entities_collector_->get_timer(i)->is_ready()) {
-        auto timer = entities_collector_->get_timer(i);
-        timer->call();
-        execute_timer(std::move(timer));
-        if (spin_once) {
-          return true;
-        }
-        any_ready_executable = true;
+
+  auto rcl_wait_set = wait_result.get_wait_set().get_rcl_wait_set();
+
+  for (size_t ii = 0; ii < rcl_wait_set.size_of_timers; ++ii) {
+    if (nullptr == rcl_wait_set.timers[ii]) {continue;}
+    auto entity_iter = collection.timers.find(rcl_wait_set.timers[ii]);
+    if (entity_iter != collection.timers.end()) {
+      auto entity = entity_iter->second.entity.lock();
+      if (!entity) {
+        continue;
       }
-    }
-  }
-  // Execute all the ready services
-  for (size_t i = 0; i < wait_set_.size_of_services; ++i) {
-    if (i < entities_collector_->get_number_of_services()) {
-      if (wait_set_.services[i]) {
-        execute_service(entities_collector_->get_service(i));
-        if (spin_once) {
-          return true;
-        }
-        any_ready_executable = true;
+      if (!entity->call()) {
+        continue;
       }
-    }
-  }
-  // Execute all the ready clients
-  for (size_t i = 0; i < wait_set_.size_of_clients; ++i) {
-    if (i < entities_collector_->get_number_of_clients()) {
-      if (wait_set_.clients[i]) {
-        execute_client(entities_collector_->get_client(i));
-        if (spin_once) {
-          return true;
-        }
-        any_ready_executable = true;
-      }
-    }
-  }
-  // Execute all the ready waitables
-  for (size_t i = 0; i < entities_collector_->get_number_of_waitables(); ++i) {
-    auto waitable = entities_collector_->get_waitable(i);
-    if (waitable->is_ready(&wait_set_)) {
-      auto data = waitable->take_data();
-      waitable->execute(data);
+      execute_timer(entity);
       if (spin_once) {
         return true;
       }
       any_ready_executable = true;
     }
   }
+
+  for (size_t ii = 0; ii < rcl_wait_set.size_of_subscriptions; ++ii) {
+    if (nullptr == rcl_wait_set.subscriptions[ii]) {continue;}
+    auto entity_iter = collection.subscriptions.find(rcl_wait_set.subscriptions[ii]);
+    if (entity_iter != collection.subscriptions.end()) {
+      auto entity = entity_iter->second.entity.lock();
+      if (!entity) {
+        continue;
+      }
+      execute_subscription(entity);
+      if (spin_once) {
+        return true;
+      }
+      any_ready_executable = true;
+    }
+  }
+
+  for (size_t ii = 0; ii < rcl_wait_set.size_of_services; ++ii) {
+    if (nullptr == rcl_wait_set.services[ii]) {continue;}
+    auto entity_iter = collection.services.find(rcl_wait_set.services[ii]);
+    if (entity_iter != collection.services.end()) {
+      auto entity = entity_iter->second.entity.lock();
+      if (!entity) {
+        continue;
+      }
+      execute_service(entity);
+      if (spin_once) {
+        return true;
+      }
+      any_ready_executable = true;
+    }
+  }
+
+  for (size_t ii = 0; ii < rcl_wait_set.size_of_clients; ++ii) {
+    if (nullptr == rcl_wait_set.clients[ii]) {continue;}
+    auto entity_iter = collection.clients.find(rcl_wait_set.clients[ii]);
+    if (entity_iter != collection.clients.end()) {
+      auto entity = entity_iter->second.entity.lock();
+      if (!entity) {
+        continue;
+      }
+      execute_client(entity);
+      if (spin_once) {
+        return true;
+      }
+      any_ready_executable = true;
+    }
+  }
+
+  for (auto & [handle, entry] : collection.waitables) {
+    auto waitable = entry.entity.lock();
+    if (!waitable) {
+      continue;
+    }
+    if (!waitable->is_ready(&rcl_wait_set)) {
+      continue;
+    }
+
+    auto data = waitable->take_data();
+    waitable->execute(data);
+    if (spin_once) {
+      return true;
+    }
+    any_ready_executable = true;
+  }
   return any_ready_executable;
 }

rclcpp/src/rclcpp/experimental/executors/events_executor/events_executor.cpp

@@ -0,0 +1,488 @@
+// Copyright 2023 iRobot Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "rclcpp/experimental/executors/events_executor/events_executor.hpp"
+
+#include <memory>
+#include <utility>
+#include <vector>
+
+#include "rcpputils/scope_exit.hpp"
+
+using namespace std::chrono_literals;
+
+using rclcpp::experimental::executors::EventsExecutor;
+
+EventsExecutor::EventsExecutor(
+  rclcpp::experimental::executors::EventsQueue::UniquePtr events_queue,
+  bool execute_timers_separate_thread,
+  const rclcpp::ExecutorOptions & options)
+: rclcpp::Executor(options)
+{
+  // Get ownership of the queue used to store events.
+  if (!events_queue) {
+    throw std::invalid_argument("events_queue can't be a null pointer");
+  }
+  events_queue_ = std::move(events_queue);
+
+  // Create timers manager
+  // The timers manager can be used either to only track timers (in this case an expired
+  // timer will generate an executor event and then it will be executed by the executor thread)
+  // or it can also take care of executing expired timers in its dedicated thread.
+  std::function<void(const rclcpp::TimerBase *)> timer_on_ready_cb = nullptr;
+  if (!execute_timers_separate_thread) {
+    timer_on_ready_cb = [this](const rclcpp::TimerBase * timer_id) {
+        ExecutorEvent event = {timer_id, -1, ExecutorEventType::TIMER_EVENT, 1};
+        this->events_queue_->enqueue(event);
+      };
+  }
+  timers_manager_ =
+    std::make_shared<rclcpp::experimental::TimersManager>(context_, timer_on_ready_cb);
+
+  notify_waitable_ = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>(
+    [this]() {
+      // This callback is invoked when:
+      // - the interrupt or shutdown guard condition is triggered:
+      //    ---> we need to wake up the executor so that it can terminate
+      // - a node or callback group guard condition is triggered:
+      //    ---> the entities collection is changed, we need to update callbacks
+      notify_waitable_event_pushed_ = false;
+      this->refresh_current_collection_from_callback_groups();
+    });
+
+  notify_waitable_->add_guard_condition(interrupt_guard_condition_);
+  notify_waitable_->add_guard_condition(shutdown_guard_condition_);
+
+  notify_waitable_->set_on_ready_callback(
+    this->create_waitable_callback(notify_waitable_.get()));
+
+  auto notify_waitable_entity_id = notify_waitable_.get();
+  notify_waitable_->set_on_ready_callback(
+    [this, notify_waitable_entity_id](size_t num_events, int waitable_data) {
+      // The notify waitable has a special callback.
+      // We don't care about how many events as when we wake up the executor we are going to
+      // process everything regardless.
+      // For the same reason, if an event of this type has already been pushed but it has not been
+      // processed yet, we avoid pushing additional events.
+      (void)num_events;
+      if (notify_waitable_event_pushed_.exchange(true)) {
+        return;
+      }
+
+      ExecutorEvent event =
+      {notify_waitable_entity_id, waitable_data, ExecutorEventType::WAITABLE_EVENT, 1};
+      this->events_queue_->enqueue(event);
+    });
+
+  this->entities_collector_ =
+    std::make_shared<rclcpp::executors::ExecutorEntitiesCollector>(notify_waitable_);
+
+  this->current_entities_collection_ =
+    std::make_shared<rclcpp::executors::ExecutorEntitiesCollection>();
+}
+
+EventsExecutor::~EventsExecutor()
+{
+  spinning.store(false);
+  notify_waitable_->clear_on_ready_callback();
+  this->refresh_current_collection({});
+}
+
+void
+EventsExecutor::spin()
+{
+  if (spinning.exchange(true)) {
+    throw std::runtime_error("spin() called while already spinning");
+  }
+  RCPPUTILS_SCOPE_EXIT(this->spinning.store(false); );
+
+  timers_manager_->start();
+  RCPPUTILS_SCOPE_EXIT(timers_manager_->stop(); );
+
+  while (rclcpp::ok(context_) && spinning.load()) {
+    // Wait until we get an event
+    ExecutorEvent event;
+    bool has_event = events_queue_->dequeue(event);
+    if (has_event) {
+      this->execute_event(event);
+    }
+  }
+}
+
+void
+EventsExecutor::spin_some(std::chrono::nanoseconds max_duration)
+{
+  return this->spin_some_impl(max_duration, false);
+}
+
+void
+EventsExecutor::spin_all(std::chrono::nanoseconds max_duration)
+{
+  if (max_duration <= 0ns) {
+    throw std::invalid_argument("max_duration must be positive");
+  }
+  return this->spin_some_impl(max_duration, true);
+}
+
+void
+EventsExecutor::spin_some_impl(std::chrono::nanoseconds max_duration, bool exhaustive)
+{
+  if (spinning.exchange(true)) {
+    throw std::runtime_error("spin_some() called while already spinning");
+  }
+
+  RCPPUTILS_SCOPE_EXIT(this->spinning.store(false); );
+
+  auto start = std::chrono::steady_clock::now();
+
+  auto max_duration_not_elapsed = [max_duration, start]() {
+      if (std::chrono::nanoseconds(0) == max_duration) {
+        // told to spin forever if need be
+        return true;
+      } else if (std::chrono::steady_clock::now() - start < max_duration) {
+        // told to spin only for some maximum amount of time
+        return true;
+      }
+      // spun too long
+      return false;
+    };
+
+  // Get the number of events and timers ready at start
+  const size_t ready_events_at_start = events_queue_->size();
+  size_t executed_events = 0;
+  const size_t ready_timers_at_start = timers_manager_->get_number_ready_timers();
+  size_t executed_timers = 0;
+
+  while (rclcpp::ok(context_) && spinning.load() && max_duration_not_elapsed()) {
+    // Execute first ready event from queue if exists
+    if (exhaustive || (executed_events < ready_events_at_start)) {
+      bool has_event = !events_queue_->empty();
+
+      if (has_event) {
+        ExecutorEvent event;
+        bool ret = events_queue_->dequeue(event, std::chrono::nanoseconds(0));
+        if (ret) {
+          this->execute_event(event);
+          executed_events++;
+          continue;
+        }
+      }
+    }
+
+    // Execute first timer if it is ready
+    if (exhaustive || (executed_timers < ready_timers_at_start)) {
+      bool timer_executed = timers_manager_->execute_head_timer();
+      if (timer_executed) {
+        executed_timers++;
+        continue;
+      }
+    }
+
+    // If there's no more work available, exit
+    break;
+  }
+}
+
+void
+EventsExecutor::spin_once_impl(std::chrono::nanoseconds timeout)
+{
+  // In this context a negative input timeout means no timeout
+  if (timeout < 0ns) {
+    timeout = std::chrono::nanoseconds::max();
+  }
+
+  // Select the smallest between input timeout and timer timeout
+  bool is_timer_timeout = false;
+  auto next_timer_timeout = timers_manager_->get_head_timeout();
+  if (next_timer_timeout < timeout) {
+    timeout = next_timer_timeout;
+    is_timer_timeout = true;
+  }
+
+  ExecutorEvent event;
+  bool has_event = events_queue_->dequeue(event, timeout);
+
+  // If we wake up from the wait with an event, it means that it
+  // arrived before any of the timers expired.
+  if (has_event) {
+    this->execute_event(event);
+  } else if (is_timer_timeout) {
+    timers_manager_->execute_head_timer();
+  }
+}
+
+void
+EventsExecutor::add_node(
+  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr, bool notify)
+{
+  // This field is unused because we don't have to wake up the executor when a node is added.
+  (void) notify;
+
+  // Add node to entities collector
+  this->entities_collector_->add_node(node_ptr);
+
+  this->refresh_current_collection_from_callback_groups();
+}
+
+void
+EventsExecutor::add_node(std::shared_ptr<rclcpp::Node> node_ptr, bool notify)
+{
+  this->add_node(node_ptr->get_node_base_interface(), notify);
+}
+
+void
+EventsExecutor::remove_node(
+  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr, bool notify)
+{
+  // This field is unused because we don't have to wake up the executor when a node is removed.
+  (void)notify;
+
+  // Remove node from entities collector.
+  // This will result in un-setting all the event callbacks from its entities.
+  // After this function returns, this executor will not receive any more events associated
+  // to these entities.
+  this->entities_collector_->remove_node(node_ptr);
+
+  this->refresh_current_collection_from_callback_groups();
+}
+
+void
+EventsExecutor::remove_node(std::shared_ptr<rclcpp::Node> node_ptr, bool notify)
+{
+  this->remove_node(node_ptr->get_node_base_interface(), notify);
+}
+
+void
+EventsExecutor::execute_event(const ExecutorEvent & event)
+{
+  switch (event.type) {
+    case ExecutorEventType::CLIENT_EVENT:
+      {
+        auto client = this->retrieve_entity(
+          static_cast<const rcl_client_t *>(event.entity_key),
+          current_entities_collection_->clients);
+
+        if (client) {
+          for (size_t i = 0; i < event.num_events; i++) {
+            execute_client(client);
+          }
+        }
+
+        break;
+      }
+    case ExecutorEventType::SUBSCRIPTION_EVENT:
+      {
+        auto subscription = this->retrieve_entity(
+          static_cast<const rcl_subscription_t *>(event.entity_key),
+          current_entities_collection_->subscriptions);
+        if (subscription) {
+          for (size_t i = 0; i < event.num_events; i++) {
+            execute_subscription(subscription);
+          }
+        }
+        break;
+      }
+    case ExecutorEventType::SERVICE_EVENT:
+      {
+        auto service = this->retrieve_entity(
+          static_cast<const rcl_service_t *>(event.entity_key),
+          current_entities_collection_->services);
+
+        if (service) {
+          for (size_t i = 0; i < event.num_events; i++) {
+            execute_service(service);
+          }
+        }
+
+        break;
+      }
+    case ExecutorEventType::TIMER_EVENT:
+      {
+        timers_manager_->execute_ready_timer(
+          static_cast<const rclcpp::TimerBase *>(event.entity_key));
+        break;
+      }
+    case ExecutorEventType::WAITABLE_EVENT:
+      {
+        auto waitable = this->retrieve_entity(
+          static_cast<const rclcpp::Waitable *>(event.entity_key),
+          current_entities_collection_->waitables);
+        if (waitable) {
+          for (size_t i = 0; i < event.num_events; i++) {
+            auto data = waitable->take_data_by_entity_id(event.waitable_data);
+            waitable->execute(data);
+          }
+        }
+        break;
+      }
+  }
+}
+
+void
+EventsExecutor::add_callback_group(
+  rclcpp::CallbackGroup::SharedPtr group_ptr,
+  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
+  bool notify)
+{
+  // This field is unused because we don't have to wake up
+  // the executor when a callback group is added.
+  (void)notify;
+  (void)node_ptr;
+
+  this->entities_collector_->add_callback_group(group_ptr);
+
+  this->refresh_current_collection_from_callback_groups();
+}
+
+void
+EventsExecutor::remove_callback_group(
+  rclcpp::CallbackGroup::SharedPtr group_ptr, bool notify)
+{
+  // This field is unused because we don't have to wake up
+  // the executor when a callback group is removed.
+  (void)notify;
+
+  this->entities_collector_->remove_callback_group(group_ptr);
+
+  this->refresh_current_collection_from_callback_groups();
+}
+
+std::vector<rclcpp::CallbackGroup::WeakPtr>
+EventsExecutor::get_all_callback_groups()
+{
+  this->entities_collector_->update_collections();
+  return this->entities_collector_->get_all_callback_groups();
+}
+
+std::vector<rclcpp::CallbackGroup::WeakPtr>
+EventsExecutor::get_manually_added_callback_groups()
+{
+  this->entities_collector_->update_collections();
+  return this->entities_collector_->get_manually_added_callback_groups();
+}
+
+std::vector<rclcpp::CallbackGroup::WeakPtr>
+EventsExecutor::get_automatically_added_callback_groups_from_nodes()
+{
+  this->entities_collector_->update_collections();
+  return this->entities_collector_->get_automatically_added_callback_groups();
+}
+
+void
+EventsExecutor::refresh_current_collection_from_callback_groups()
+{
+  this->entities_collector_->update_collections();
+  auto callback_groups = this->entities_collector_->get_all_callback_groups();
+  rclcpp::executors::ExecutorEntitiesCollection new_collection;
+  rclcpp::executors::build_entities_collection(callback_groups, new_collection);
+
+  // TODO(alsora): this may be implemented in a better way.
+  // We need the notify waitable to be included in the executor "current_collection"
+  // because we need to be able to retrieve events for it.
+  // We could explicitly check for the notify waitable ID when we receive a waitable event
+  // but I think that it's better if the waitable was in the collection and it could be
+  // retrieved in the "standard" way.
+  // To do it, we need to add the notify waitable as an entry in both the new and
+  // current collections such that it's neither added or removed.
+  rclcpp::CallbackGroup::WeakPtr weak_group_ptr;
+  new_collection.waitables.insert(
+  {
+    this->notify_waitable_.get(),
+    {this->notify_waitable_, weak_group_ptr}
+  });
+
+  this->current_entities_collection_->waitables.insert(
+  {
+    this->notify_waitable_.get(),
+    {this->notify_waitable_, weak_group_ptr}
+  });
+
+  this->refresh_current_collection(new_collection);
+}
+
+void
+EventsExecutor::refresh_current_collection(
+  const rclcpp::executors::ExecutorEntitiesCollection & new_collection)
+{
+  current_entities_collection_->timers.update(
+    new_collection.timers,
+    [this](rclcpp::TimerBase::SharedPtr timer) {timers_manager_->add_timer(timer);},
+    [this](rclcpp::TimerBase::SharedPtr timer) {timers_manager_->remove_timer(timer);});
+
+  current_entities_collection_->subscriptions.update(
+    new_collection.subscriptions,
+    [this](auto subscription) {
+      subscription->set_on_new_message_callback(
+        this->create_entity_callback(
+          subscription->get_subscription_handle().get(), ExecutorEventType::SUBSCRIPTION_EVENT));
+    },
+    [](auto subscription) {subscription->clear_on_new_message_callback();});
+
+  current_entities_collection_->clients.update(
+    new_collection.clients,
+    [this](auto client) {
+      client->set_on_new_response_callback(
+        this->create_entity_callback(
+          client->get_client_handle().get(), ExecutorEventType::CLIENT_EVENT));
+    },
+    [](auto client) {client->clear_on_new_response_callback();});
+
+  current_entities_collection_->services.update(
+    new_collection.services,
+    [this](auto service) {
+      service->set_on_new_request_callback(
+        this->create_entity_callback(
+          service->get_service_handle().get(), ExecutorEventType::SERVICE_EVENT));
+    },
+    [](auto service) {service->clear_on_new_request_callback();});
+
+  // DO WE NEED THIS? WE ARE NOT DOING ANYTHING WITH GUARD CONDITIONS
+  /*
+  current_entities_collection_->guard_conditions.update(new_collection.guard_conditions,
+    [](auto guard_condition) {(void)guard_condition;},
+    [](auto guard_condition) {guard_condition->set_on_trigger_callback(nullptr);});
+  */
+
+  current_entities_collection_->waitables.update(
+    new_collection.waitables,
+    [this](auto waitable) {
+      waitable->set_on_ready_callback(
+        this->create_waitable_callback(waitable.get()));
+    },
+    [](auto waitable) {waitable->clear_on_ready_callback();});
+}
+
+std::function<void(size_t)>
+EventsExecutor::create_entity_callback(
+  void * entity_key, ExecutorEventType event_type)
+{
+  std::function<void(size_t)>
+  callback = [this, entity_key, event_type](size_t num_events) {
+      ExecutorEvent event = {entity_key, -1, event_type, num_events};
+      this->events_queue_->enqueue(event);
+    };
+  return callback;
+}
+
+std::function<void(size_t, int)>
+EventsExecutor::create_waitable_callback(const rclcpp::Waitable * entity_key)
+{
+  std::function<void(size_t, int)>
+  callback = [this, entity_key](size_t num_events, int waitable_data) {
+      ExecutorEvent event =
+      {entity_key, waitable_data, ExecutorEventType::WAITABLE_EVENT, num_events};
+      this->events_queue_->enqueue(event);
+    };
+  return callback;
+}

rclcpp/src/rclcpp/experimental/timers_manager.cpp

@@ -0,0 +1,299 @@
+// Copyright 2023 iRobot Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "rclcpp/experimental/timers_manager.hpp"
+
+#include <inttypes.h>
+
+#include <ctime>
+#include <iostream>
+#include <memory>
+#include <stdexcept>
+
+#include "rcpputils/scope_exit.hpp"
+
+using rclcpp::experimental::TimersManager;
+
+TimersManager::TimersManager(
+  std::shared_ptr<rclcpp::Context> context,
+  std::function<void(const rclcpp::TimerBase *)> on_ready_callback)
+{
+  context_ = context;
+  on_ready_callback_ = on_ready_callback;
+}
+
+TimersManager::~TimersManager()
+{
+  // Remove all timers
+  this->clear();
+
+  // Make sure timers thread is stopped before destroying this object
+  this->stop();
+}
+
+void TimersManager::add_timer(rclcpp::TimerBase::SharedPtr timer)
+{
+  if (!timer) {
+    throw std::invalid_argument("TimersManager::add_timer() trying to add nullptr timer");
+  }
+
+  bool added = false;
+  {
+    std::unique_lock<std::mutex> lock(timers_mutex_);
+    added = weak_timers_heap_.add_timer(timer);
+    timers_updated_ = timers_updated_ || added;
+  }
+
+  timer->set_on_reset_callback(
+    [this](size_t arg) {
+      {
+        (void)arg;
+        std::unique_lock<std::mutex> lock(timers_mutex_);
+        timers_updated_ = true;
+      }
+      timers_cv_.notify_one();
+    });
+
+  if (added) {
+    // Notify that a timer has been added
+    timers_cv_.notify_one();
+  }
+}
+
+void TimersManager::start()
+{
+  // Make sure that the thread is not already running
+  if (running_.exchange(true)) {
+    throw std::runtime_error("TimersManager::start() can't start timers thread as already running");
+  }
+
+  timers_thread_ = std::thread(&TimersManager::run_timers, this);
+}
+
+void TimersManager::stop()
+{
+  // Lock stop() function to prevent race condition in destructor
+  std::unique_lock<std::mutex> lock(stop_mutex_);
+  running_ = false;
+
+  // Notify the timers manager thread to wake up
+  {
+    std::unique_lock<std::mutex> lock(timers_mutex_);
+    timers_updated_ = true;
+  }
+  timers_cv_.notify_one();
+
+  // Join timers thread if it's running
+  if (timers_thread_.joinable()) {
+    timers_thread_.join();
+  }
+}
+
+std::chrono::nanoseconds TimersManager::get_head_timeout()
+{
+  // Do not allow to interfere with the thread running
+  if (running_) {
+    throw std::runtime_error(
+            "get_head_timeout() can't be used while timers thread is running");
+  }
+
+  std::unique_lock<std::mutex> lock(timers_mutex_);
+  return this->get_head_timeout_unsafe();
+}
+
+size_t TimersManager::get_number_ready_timers()
+{
+  // Do not allow to interfere with the thread running
+  if (running_) {
+    throw std::runtime_error(
+            "get_number_ready_timers() can't be used while timers thread is running");
+  }
+
+  std::unique_lock<std::mutex> lock(timers_mutex_);
+  TimersHeap locked_heap = weak_timers_heap_.validate_and_lock();
+  return locked_heap.get_number_ready_timers();
+}
+
+bool TimersManager::execute_head_timer()
+{
+  // Do not allow to interfere with the thread running
+  if (running_) {
+    throw std::runtime_error(
+            "execute_head_timer() can't be used while timers thread is running");
+  }
+
+  std::unique_lock<std::mutex> lock(timers_mutex_);
+
+  TimersHeap timers_heap = weak_timers_heap_.validate_and_lock();
+
+  // Nothing to do if we don't have any timer
+  if (timers_heap.empty()) {
+    return false;
+  }
+
+  TimerPtr head_timer = timers_heap.front();
+
+  const bool timer_ready = head_timer->is_ready();
+  if (timer_ready) {
+    // NOTE: here we always execute the timer, regardless of whether the
+    // on_ready_callback is set or not.
+    head_timer->call();
+    head_timer->execute_callback();
+    timers_heap.heapify_root();
+    weak_timers_heap_.store(timers_heap);
+  }
+
+  return timer_ready;
+}
+
+void TimersManager::execute_ready_timer(const rclcpp::TimerBase * timer_id)
+{
+  TimerPtr ready_timer;
+  {
+    std::unique_lock<std::mutex> lock(timers_mutex_);
+    ready_timer = weak_timers_heap_.get_timer(timer_id);
+  }
+  if (ready_timer) {
+    ready_timer->execute_callback();
+  }
+}
+
+std::chrono::nanoseconds TimersManager::get_head_timeout_unsafe()
+{
+  // If we don't have any weak pointer, then we just return maximum timeout
+  if (weak_timers_heap_.empty()) {
+    return std::chrono::nanoseconds::max();
+  }
+  // Weak heap is not empty, so try to lock the first element.
+  // If it is still a valid pointer, it is guaranteed to be the correct head
+  TimerPtr head_timer = weak_timers_heap_.front().lock();
+
+  if (!head_timer) {
+    // The first element has expired, we can't make other assumptions on the heap
+    // and we need to entirely validate it.
+    TimersHeap locked_heap = weak_timers_heap_.validate_and_lock();
+    // NOTE: the following operations will not modify any element in the heap, so we
+    // don't have to call `weak_timers_heap_.store(locked_heap)` at the end.
+
+    if (locked_heap.empty()) {
+      return std::chrono::nanoseconds::max();
+    }
+    head_timer = locked_heap.front();
+  }
+
+  return head_timer->time_until_trigger();
+}
+
+void TimersManager::execute_ready_timers_unsafe()
+{
+  // We start by locking the timers
+  TimersHeap locked_heap = weak_timers_heap_.validate_and_lock();
+
+  // Nothing to do if we don't have any timer
+  if (locked_heap.empty()) {
+    return;
+  }
+
+  // Keep executing timers until they are ready and they were already ready when we started.
+  // The two checks prevent this function from blocking indefinitely if the
+  // time required for executing the timers is longer than their period.
+
+  TimerPtr head_timer = locked_heap.front();
+  const size_t number_ready_timers = locked_heap.get_number_ready_timers();
+  size_t executed_timers = 0;
+  while (executed_timers < number_ready_timers && head_timer->is_ready()) {
+    head_timer->call();
+    if (on_ready_callback_) {
+      on_ready_callback_(head_timer.get());
+    } else {
+      head_timer->execute_callback();
+    }
+
+    executed_timers++;
+    // Executing a timer will result in updating its time_until_trigger, so re-heapify
+    locked_heap.heapify_root();
+    // Get new head timer
+    head_timer = locked_heap.front();
+  }
+
+  // After having performed work on the locked heap we reflect the changes to weak one.
+  // Timers will be already sorted the next time we need them if none went out of scope.
+  weak_timers_heap_.store(locked_heap);
+}
+
+void TimersManager::run_timers()
+{
+  // Make sure the running flag is set to false when we exit from this function
+  // to allow restarting the timers thread.
+  RCPPUTILS_SCOPE_EXIT(this->running_.store(false); );
+
+  while (rclcpp::ok(context_) && running_) {
+    // Lock mutex
+    std::unique_lock<std::mutex> lock(timers_mutex_);
+
+    std::chrono::nanoseconds time_to_sleep = get_head_timeout_unsafe();
+
+    // No need to wait if a timer is already available
+    if (time_to_sleep > std::chrono::nanoseconds::zero()) {
+      if (time_to_sleep != std::chrono::nanoseconds::max()) {
+        // Wait until timeout or notification that timers have been updated
+        timers_cv_.wait_for(lock, time_to_sleep, [this]() {return timers_updated_;});
+      } else {
+        // Wait until notification that timers have been updated
+        timers_cv_.wait(lock, [this]() {return timers_updated_;});
+      }
+    }
+
+    // Reset timers updated flag
+    timers_updated_ = false;
+
+    // Execute timers
+    this->execute_ready_timers_unsafe();
+  }
+}
+
+void TimersManager::clear()
+{
+  {
+    // Lock mutex and then clear all data structures
+    std::unique_lock<std::mutex> lock(timers_mutex_);
+
+    TimersHeap locked_heap = weak_timers_heap_.validate_and_lock();
+    locked_heap.clear_timers_on_reset_callbacks();
+
+    weak_timers_heap_.clear();
+
+    timers_updated_ = true;
+  }
+
+  // Notify timers thread such that it can re-compute its timeout
+  timers_cv_.notify_one();
+}
+
+void TimersManager::remove_timer(TimerPtr timer)
+{
+  bool removed = false;
+  {
+    std::unique_lock<std::mutex> lock(timers_mutex_);
+    removed = weak_timers_heap_.remove_timer(timer);
+
+    timers_updated_ = timers_updated_ || removed;
+  }
+
+  if (removed) {
+    // Notify timers thread such that it can re-compute its timeout
+    timers_cv_.notify_one();
+    timer->clear_on_reset_callback();
+  }
+}

rclcpp/src/rclcpp/generic_subscription.cpp

@@ -25,17 +25,20 @@
 namespace rclcpp
 {
 
-std::shared_ptr<void> GenericSubscription::create_message()
+std::shared_ptr<void>
+GenericSubscription::create_message()
 {
   return create_serialized_message();
 }
 
-std::shared_ptr<rclcpp::SerializedMessage> GenericSubscription::create_serialized_message()
+std::shared_ptr<rclcpp::SerializedMessage>
+GenericSubscription::create_serialized_message()
 {
   return std::make_shared<rclcpp::SerializedMessage>(0);
 }
 
-void GenericSubscription::handle_message(
+void
+GenericSubscription::handle_message(
   std::shared_ptr<void> &,
   const rclcpp::MessageInfo &)
 {
@@ -51,7 +54,8 @@ GenericSubscription::handle_serialized_message(
   callback_(message);
 }
 
-void GenericSubscription::handle_loaned_message(
+void
+GenericSubscription::handle_loaned_message(
   void * message, const rclcpp::MessageInfo & message_info)
 {
   (void) message;
@@ -60,16 +64,69 @@ void GenericSubscription::handle_loaned_message(
           "handle_loaned_message is not implemented for GenericSubscription");
 }
 
-void GenericSubscription::return_message(std::shared_ptr<void> & message)
+void
+GenericSubscription::return_message(std::shared_ptr<void> & message)
 {
   auto typed_message = std::static_pointer_cast<rclcpp::SerializedMessage>(message);
   return_serialized_message(typed_message);
 }
 
-void GenericSubscription::return_serialized_message(
+void
+GenericSubscription::return_serialized_message(
   std::shared_ptr<rclcpp::SerializedMessage> & message)
 {
   message.reset();
 }
 
+
+// DYNAMIC TYPE ====================================================================================
+// TODO(methylDragon): Reorder later
+rclcpp::dynamic_typesupport::DynamicMessageType::SharedPtr
+GenericSubscription::get_shared_dynamic_message_type()
+{
+  throw rclcpp::exceptions::UnimplementedError(
+          "get_shared_dynamic_message_type is not implemented for GenericSubscription");
+}
+
+rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr
+GenericSubscription::get_shared_dynamic_message()
+{
+  throw rclcpp::exceptions::UnimplementedError(
+          "get_shared_dynamic_message is not implemented for GenericSubscription");
+}
+
+rclcpp::dynamic_typesupport::DynamicSerializationSupport::SharedPtr
+GenericSubscription::get_shared_dynamic_serialization_support()
+{
+  throw rclcpp::exceptions::UnimplementedError(
+          "get_shared_dynamic_serialization_support is not implemented for GenericSubscription");
+}
+
+rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr
+GenericSubscription::create_dynamic_message()
+{
+  throw rclcpp::exceptions::UnimplementedError(
+          "create_dynamic_message is not implemented for GenericSubscription");
+}
+
+void
+GenericSubscription::return_dynamic_message(
+  rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr & message)
+{
+  (void) message;
+  throw rclcpp::exceptions::UnimplementedError(
+          "return_dynamic_message is not implemented for GenericSubscription");
+}
+
+void
+GenericSubscription::handle_dynamic_message(
+  const rclcpp::dynamic_typesupport::DynamicMessage::SharedPtr & message,
+  const rclcpp::MessageInfo & message_info)
+{
+  (void) message;
+  (void) message_info;
+  throw rclcpp::exceptions::UnimplementedError(
+          "handle_dynamic_message is not implemented for GenericSubscription");
+}
+
 }  // namespace rclcpp

rclcpp/src/rclcpp/node_interfaces/node_base.cpp

@@ -45,7 +45,7 @@ NodeBase::NodeBase(
   node_handle_(nullptr),
   default_callback_group_(default_callback_group),
   associated_with_executor_(false),
-  notify_guard_condition_(context),
+  notify_guard_condition_(std::make_shared<rclcpp::GuardCondition>(context)),
   notify_guard_condition_is_valid_(false)
 {
   // Create the rcl node and store it in a shared_ptr with a custom destructor.
@@ -132,8 +132,10 @@ NodeBase::NodeBase(
   // Create the default callback group, if needed.
   if (nullptr == default_callback_group_) {
     using rclcpp::CallbackGroupType;
+    // Default callback group is mutually exclusive and automatically associated with
+    // any executors that this node is added to.
     default_callback_group_ =
-      NodeBase::create_callback_group(CallbackGroupType::MutuallyExclusive);
+      NodeBase::create_callback_group(CallbackGroupType::MutuallyExclusive, true);
   }
 
   // Indicate the notify_guard_condition is now valid.
@@ -202,11 +204,27 @@ NodeBase::create_callback_group(
   rclcpp::CallbackGroupType group_type,
   bool automatically_add_to_executor_with_node)
 {
+  auto weak_context = this->get_context()->weak_from_this();
+  auto get_node_context = [weak_context]() -> rclcpp::Context::SharedPtr {
+      return weak_context.lock();
+    };
+
   auto group = std::make_shared<rclcpp::CallbackGroup>(
     group_type,
+    get_node_context,
     automatically_add_to_executor_with_node);
   std::lock_guard<std::mutex> lock(callback_groups_mutex_);
   callback_groups_.push_back(group);
+
+  // This guard condition is generally used to signal to this node's executor that a callback
+  // group has been added that should be considered for new entities.
+  // If this is creating the default callback group, then the notify guard condition won't be
+  // ready or needed yet, as the node is not done being constructed and therefore cannot be added.
+  // If the callback group is not automatically associated with this node's executors, then
+  // triggering the guard condition is also unnecessary, it will be manually added to an exector.
+  if (notify_guard_condition_is_valid_ && automatically_add_to_executor_with_node) {
+    this->trigger_notify_guard_condition();
+  }
   return group;
 }
 
@@ -253,9 +271,29 @@ NodeBase::get_notify_guard_condition()
   if (!notify_guard_condition_is_valid_) {
     throw std::runtime_error("failed to get notify guard condition because it is invalid");
   }
+  return *notify_guard_condition_;
+}
+
+rclcpp::GuardCondition::SharedPtr
+NodeBase::get_shared_notify_guard_condition()
+{
+  std::lock_guard<std::recursive_mutex> notify_condition_lock(notify_guard_condition_mutex_);
+  if (!notify_guard_condition_is_valid_) {
+    return nullptr;
+  }
   return notify_guard_condition_;
 }
 
+void
+NodeBase::trigger_notify_guard_condition()
+{
+  std::lock_guard<std::recursive_mutex> notify_condition_lock(notify_guard_condition_mutex_);
+  if (!notify_guard_condition_is_valid_) {
+    throw std::runtime_error("failed to trigger notify guard condition because it is invalid");
+  }
+  notify_guard_condition_->trigger();
+}
+
 bool
 NodeBase::get_use_intra_process_default() const
 {

rclcpp/src/rclcpp/node_interfaces/node_graph.cpp

@@ -533,9 +533,8 @@ NodeGraph::notify_graph_change()
     }
   }
   graph_cv_.notify_all();
-  auto & node_gc = node_base_->get_notify_guard_condition();
   try {
-    node_gc.trigger();
+    node_base_->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(
             std::string("failed to notify wait set on graph change: ") + ex.what());
@@ -789,3 +788,15 @@ rclcpp::TopicEndpointInfo::qos_profile() const
 {
   return qos_profile_;
 }
+
+rosidl_type_hash_t &
+rclcpp::TopicEndpointInfo::topic_type_hash()
+{
+  return topic_type_hash_;
+}
+
+const rosidl_type_hash_t &
+rclcpp::TopicEndpointInfo::topic_type_hash() const
+{
+  return topic_type_hash_;
+}

rclcpp/src/rclcpp/node_interfaces/node_services.cpp

@@ -42,9 +42,8 @@ NodeServices::add_service(
   group->add_service(service_base_ptr);
 
   // Notify the executor that a new service was created using the parent Node.
-  auto & node_gc = node_base_->get_notify_guard_condition();
   try {
-    node_gc.trigger();
+    node_base_->trigger_notify_guard_condition();
     group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(
@@ -69,9 +68,8 @@ NodeServices::add_client(
   group->add_client(client_base_ptr);
 
   // Notify the executor that a new client was created using the parent Node.
-  auto & node_gc = node_base_->get_notify_guard_condition();
   try {
-    node_gc.trigger();
+    node_base_->trigger_notify_guard_condition();
     group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(

rclcpp/src/rclcpp/node_interfaces/node_timers.cpp

@@ -42,9 +42,8 @@ NodeTimers::add_timer(
   }
   callback_group->add_timer(timer);
 
-  auto & node_gc = node_base_->get_notify_guard_condition();
   try {
-    node_gc.trigger();
+    node_base_->trigger_notify_guard_condition();
     callback_group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(

rclcpp/src/rclcpp/node_interfaces/node_topics.cpp

@@ -70,9 +70,8 @@ NodeTopics::add_publisher(
   }
 
   // Notify the executor that a new publisher was created using the parent Node.
-  auto & node_gc = node_base_->get_notify_guard_condition();
   try {
-    node_gc.trigger();
+    node_base_->trigger_notify_guard_condition();
     callback_group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(
@@ -119,9 +118,8 @@ NodeTopics::add_subscription(
   }
 
   // Notify the executor that a new subscription was created using the parent Node.
-  auto & node_gc = node_base_->get_notify_guard_condition();
   try {
-    node_gc.trigger();
+    node_base_->trigger_notify_guard_condition();
     callback_group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(

rclcpp/src/rclcpp/node_interfaces/node_waitables.cpp

@@ -42,9 +42,8 @@ NodeWaitables::add_waitable(
   group->add_waitable(waitable_ptr);
 
   // Notify the executor that a new waitable was created using the parent Node.
-  auto & node_gc = node_base_->get_notify_guard_condition();
   try {
-    node_gc.trigger();
+    node_base_->trigger_notify_guard_condition();
     group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(

rclcpp/src/rclcpp/subscription_base.cpp

@@ -22,6 +22,7 @@
 
 #include "rcpputils/scope_exit.hpp"
 
+#include "rclcpp/dynamic_typesupport/dynamic_message.hpp"
 #include "rclcpp/exceptions.hpp"
 #include "rclcpp/expand_topic_or_service_name.hpp"
 #include "rclcpp/experimental/intra_process_manager.hpp"
@@ -32,6 +33,8 @@
 #include "rmw/error_handling.h"
 #include "rmw/rmw.h"
 
+#include "rosidl_dynamic_typesupport/types.h"
+
 using rclcpp::SubscriptionBase;
 
 SubscriptionBase::SubscriptionBase(
@@ -41,7 +44,7 @@ SubscriptionBase::SubscriptionBase(
   const rcl_subscription_options_t & subscription_options,
   const SubscriptionEventCallbacks & event_callbacks,
   bool use_default_callbacks,
-  bool is_serialized)
+  DeliveredMessageKind delivered_message_kind)
 : node_base_(node_base),
   node_handle_(node_base_->get_shared_rcl_node_handle()),
   node_logger_(rclcpp::get_node_logger(node_handle_.get())),
@@ -49,7 +52,7 @@ SubscriptionBase::SubscriptionBase(
   intra_process_subscription_id_(0),
   event_callbacks_(event_callbacks),
   type_support_(type_support_handle),
-  is_serialized_(is_serialized)
+  delivered_message_type_(delivered_message_kind)
 {
   auto custom_deletor = [node_handle = this->node_handle_](rcl_subscription_t * rcl_subs)
     {
@@ -258,7 +261,13 @@ SubscriptionBase::get_message_type_support_handle() const
 bool
 SubscriptionBase::is_serialized() const
 {
-  return is_serialized_;
+  return delivered_message_type_ == rclcpp::DeliveredMessageKind::SERIALIZED_MESSAGE;
+}
+
+rclcpp::DeliveredMessageKind
+SubscriptionBase::get_subscription_type() const
+{
+  return delivered_message_type_;
 }
 
 size_t
@@ -442,8 +451,7 @@ SubscriptionBase::set_content_filter(
   rcl_subscription_content_filter_options_t options =
     rcl_get_zero_initialized_subscription_content_filter_options();
 
-  std::vector<const char *> cstrings =
-    get_c_vector_string(expression_parameters);
+  std::vector<const char *> cstrings = get_c_vector_string(expression_parameters);
   rcl_ret_t ret = rcl_subscription_content_filter_options_init(
     subscription_handle_.get(),
     get_c_string(filter_expression),
@@ -515,3 +523,14 @@ SubscriptionBase::get_content_filter() const
 
   return ret_options;
 }
+
+
+// DYNAMIC TYPE ==================================================================================
+bool
+SubscriptionBase::take_dynamic_message(
+  rclcpp::dynamic_typesupport::DynamicMessage & /*message_out*/,
+  rclcpp::MessageInfo & /*message_info_out*/)
+{
+  throw std::runtime_error("Unimplemented");
+  return false;
+}

rclcpp/test/benchmark/benchmark_executor.cpp

@@ -362,42 +362,3 @@ BENCHMARK_F(PerformanceTestExecutorSimple, spin_until_future_complete)(benchmark
     }
   }
 }
-
-BENCHMARK_F(
-  PerformanceTestExecutorSimple,
-  static_executor_entities_collector_execute)(benchmark::State & st)
-{
-  rclcpp::executors::StaticExecutorEntitiesCollector::SharedPtr entities_collector_ =
-    std::make_shared<rclcpp::executors::StaticExecutorEntitiesCollector>();
-  entities_collector_->add_node(node->get_node_base_interface());
-
-  rcl_wait_set_t wait_set = rcl_get_zero_initialized_wait_set();
-  rcl_allocator_t allocator = rcl_get_default_allocator();
-  auto shared_context = node->get_node_base_interface()->get_context();
-  rcl_context_t * context = shared_context->get_rcl_context().get();
-  rcl_ret_t ret = rcl_wait_set_init(&wait_set, 100, 100, 100, 100, 100, 100, context, allocator);
-  if (ret != RCL_RET_OK) {
-    st.SkipWithError(rcutils_get_error_string().str);
-  }
-  RCPPUTILS_SCOPE_EXIT(
-  {
-    rcl_ret_t ret = rcl_wait_set_fini(&wait_set);
-    if (ret != RCL_RET_OK) {
-      st.SkipWithError(rcutils_get_error_string().str);
-    }
-  });
-
-  auto memory_strategy = rclcpp::memory_strategies::create_default_strategy();
-  rclcpp::GuardCondition guard_condition(shared_context);
-
-  entities_collector_->init(&wait_set, memory_strategy);
-  RCPPUTILS_SCOPE_EXIT(entities_collector_->fini());
-
-  reset_heap_counters();
-
-  for (auto _ : st) {
-    (void)_;
-    std::shared_ptr<void> data = entities_collector_->take_data();
-    entities_collector_->execute(data);
-  }
-}

rclcpp/test/rclcpp/CMakeLists.txt

@@ -618,6 +618,14 @@ if(TARGET test_timer)
   target_link_libraries(test_timer ${PROJECT_NAME} mimick)
 endif()
 
+ament_add_gtest(test_timers_manager test_timers_manager.cpp
+  APPEND_LIBRARY_DIRS "${append_library_dirs}")
+if(TARGET test_timers_manager)
+  ament_target_dependencies(test_timers_manager
+    "rcl")
+  target_link_libraries(test_timers_manager ${PROJECT_NAME} mimick)
+endif()
+
 ament_add_gtest(test_time_source test_time_source.cpp
   APPEND_LIBRARY_DIRS "${append_library_dirs}")
 if(TARGET test_time_source)
@@ -663,14 +671,6 @@ if(TARGET test_executors)
   target_link_libraries(test_executors ${PROJECT_NAME})
 endif()
 
-ament_add_gtest(test_static_single_threaded_executor executors/test_static_single_threaded_executor.cpp
-  APPEND_LIBRARY_DIRS "${append_library_dirs}")
-if(TARGET test_static_single_threaded_executor)
-  ament_target_dependencies(test_static_single_threaded_executor
-    "test_msgs")
-  target_link_libraries(test_static_single_threaded_executor ${PROJECT_NAME} mimick)
-endif()
-
 ament_add_gtest(test_multi_threaded_executor executors/test_multi_threaded_executor.cpp
   APPEND_LIBRARY_DIRS "${append_library_dirs}")
 if(TARGET test_multi_threaded_executor)
@@ -679,13 +679,37 @@ if(TARGET test_multi_threaded_executor)
   target_link_libraries(test_multi_threaded_executor ${PROJECT_NAME})
 endif()
 
-ament_add_gtest(test_static_executor_entities_collector executors/test_static_executor_entities_collector.cpp
+ament_add_gtest(test_entities_collector executors/test_entities_collector.cpp
   APPEND_LIBRARY_DIRS "${append_library_dirs}" TIMEOUT 120)
-if(TARGET test_static_executor_entities_collector)
-  ament_target_dependencies(test_static_executor_entities_collector
+if(TARGET test_entities_collector)
+  ament_target_dependencies(test_entities_collector
     "rcl"
     "test_msgs")
-  target_link_libraries(test_static_executor_entities_collector ${PROJECT_NAME} mimick)
+  target_link_libraries(test_entities_collector ${PROJECT_NAME} mimick)
+endif()
+
+ament_add_gtest(test_executor_notify_waitable executors/test_executor_notify_waitable.cpp
+  APPEND_LIBRARY_DIRS "${append_library_dirs}" TIMEOUT 120)
+if(TARGET test_executor_notify_waitable)
+  ament_target_dependencies(test_executor_notify_waitable
+    "rcl"
+    "test_msgs")
+  target_link_libraries(test_executor_notify_waitable ${PROJECT_NAME} mimick)
+endif()
+
+ament_add_gtest(test_events_executor executors/test_events_executor.cpp TIMEOUT 5)
+if(TARGET test_events_executor)
+  ament_target_dependencies(test_events_executor
+    "test_msgs")
+  target_link_libraries(test_events_executor ${PROJECT_NAME})
+endif()
+
+ament_add_gtest(test_events_queue executors/test_events_queue.cpp
+  APPEND_LIBRARY_DIRS "${append_library_dirs}")
+if(TARGET test_events_queue)
+  ament_target_dependencies(test_events_queue
+    "test_msgs")
+  target_link_libraries(test_events_queue ${PROJECT_NAME})
 endif()
 
 ament_add_gtest(test_guard_condition test_guard_condition.cpp

rclcpp/test/rclcpp/executors/test_entities_collector.cpp

@@ -0,0 +1,320 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <gtest/gtest.h>
+
+#include "rclcpp/executors/executor_notify_waitable.hpp"
+#include "rclcpp/rclcpp.hpp"
+#include "rclcpp/executors/executor_entities_collector.hpp"
+
+#include "../../utils/rclcpp_gtest_macros.hpp"
+
+class TestExecutorEntitiesCollector : public ::testing::Test
+{
+public:
+  void SetUp()
+  {
+    rclcpp::init(0, nullptr);
+
+    notify_waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+    entities_collector = std::make_shared<rclcpp::executors::ExecutorEntitiesCollector>(
+      notify_waitable);
+  }
+
+  void TearDown()
+  {
+    rclcpp::shutdown();
+  }
+
+  std::shared_ptr<rclcpp::executors::ExecutorNotifyWaitable> notify_waitable;
+  std::shared_ptr<rclcpp::executors::ExecutorEntitiesCollector> entities_collector;
+};
+
+TEST_F(TestExecutorEntitiesCollector, add_remove_node) {
+  auto node1 = std::make_shared<rclcpp::Node>("node1", "ns");
+
+  // Add a node
+  EXPECT_NO_THROW(entities_collector->add_node(node1->get_node_base_interface()));
+  EXPECT_NO_THROW(entities_collector->update_collections());
+
+  // Remove a node
+  EXPECT_NO_THROW(entities_collector->remove_node(node1->get_node_base_interface()));
+  EXPECT_NO_THROW(entities_collector->update_collections());
+}
+
+TEST_F(TestExecutorEntitiesCollector, add_node_twice) {
+  auto node1 = std::make_shared<rclcpp::Node>("node1", "ns");
+
+  EXPECT_NO_THROW(entities_collector->add_node(node1->get_node_base_interface()));
+
+  RCLCPP_EXPECT_THROW_EQ(
+    entities_collector->add_node(node1->get_node_base_interface()),
+    std::runtime_error("Node '/ns/node1' has already been added to an executor."));
+
+  EXPECT_NO_THROW(entities_collector->update_collections());
+}
+
+TEST_F(TestExecutorEntitiesCollector, add_associated_node) {
+  auto node1 = std::make_shared<rclcpp::Node>("node1", "ns");
+
+  // Simulate node being associated somewhere else
+  auto & has_executor = node1->get_node_base_interface()->get_associated_with_executor_atomic();
+  has_executor.store(true);
+
+  // Add an already-associated node
+  RCLCPP_EXPECT_THROW_EQ(
+    entities_collector->remove_node(node1->get_node_base_interface()),
+    std::runtime_error("Node '/ns/node1' needs to be associated with this executor."));
+
+  has_executor.store(false);
+}
+
+TEST_F(TestExecutorEntitiesCollector, remove_unassociated_node) {
+  auto node1 = std::make_shared<rclcpp::Node>("node1", "ns");
+
+  // Add an already-associated node
+  RCLCPP_EXPECT_THROW_EQ(
+    entities_collector->remove_node(node1->get_node_base_interface()),
+    std::runtime_error("Node '/ns/node1' needs to be associated with an executor."));
+
+  // Simulate node being associated somewhere else
+  auto & has_executor = node1->get_node_base_interface()->get_associated_with_executor_atomic();
+  has_executor.store(true);
+
+  // Add an already-associated node
+  RCLCPP_EXPECT_THROW_EQ(
+    entities_collector->remove_node(node1->get_node_base_interface()),
+    std::runtime_error("Node '/ns/node1' needs to be associated with this executor."));
+}
+
+TEST_F(TestExecutorEntitiesCollector, add_remove_node_before_update) {
+  auto notify_waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+  auto entities_collector = rclcpp::executors::ExecutorEntitiesCollector(notify_waitable);
+
+  auto node1 = std::make_shared<rclcpp::Node>("node1", "ns");
+  auto node2 = std::make_shared<rclcpp::Node>("node2", "ns");
+
+  // Add and remove nodes without running updatenode
+  EXPECT_NO_THROW(entities_collector.add_node(node1->get_node_base_interface()));
+  EXPECT_NO_THROW(entities_collector.add_node(node2->get_node_base_interface()));
+  EXPECT_NO_THROW(entities_collector.remove_node(node1->get_node_base_interface()));
+  EXPECT_NO_THROW(entities_collector.remove_node(node2->get_node_base_interface()));
+  EXPECT_NO_THROW(entities_collector.update_collections());
+}
+
+TEST_F(TestExecutorEntitiesCollector, add_callback_group) {
+  auto notify_waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+  auto entities_collector = rclcpp::executors::ExecutorEntitiesCollector(notify_waitable);
+
+  auto node = std::make_shared<rclcpp::Node>("node1", "ns");
+  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
+    rclcpp::CallbackGroupType::MutuallyExclusive);
+
+  // Add a callback group and update
+  entities_collector.add_callback_group(cb_group);
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  entities_collector.update_collections();
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  // Remove callback group and update
+  entities_collector.remove_callback_group(cb_group);
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  entities_collector.update_collections();
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+}
+
+TEST_F(TestExecutorEntitiesCollector, add_node_default_callback_group) {
+  auto notify_waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+  auto entities_collector = rclcpp::executors::ExecutorEntitiesCollector(notify_waitable);
+
+  auto node = std::make_shared<rclcpp::Node>("node1", "ns");
+  entities_collector.add_node(node->get_node_base_interface());
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  entities_collector.update_collections();
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 1u);
+}
+
+TEST_F(TestExecutorEntitiesCollector, add_callback_group_after_add_node) {
+  auto notify_waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+  auto entities_collector = rclcpp::executors::ExecutorEntitiesCollector(notify_waitable);
+
+  auto node = std::make_shared<rclcpp::Node>("node1", "ns");
+  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
+    rclcpp::CallbackGroupType::MutuallyExclusive);
+
+  entities_collector.add_node(node->get_node_base_interface());
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  entities_collector.update_collections();
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 2u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 2u);
+
+  RCLCPP_EXPECT_THROW_EQ(
+    entities_collector.add_callback_group(cb_group),
+    std::runtime_error("Callback group has already been added to an executor."));
+}
+
+TEST_F(TestExecutorEntitiesCollector, add_callback_group_twice) {
+  auto notify_waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+  auto entities_collector = rclcpp::executors::ExecutorEntitiesCollector(notify_waitable);
+
+  auto node = std::make_shared<rclcpp::Node>("node1", "ns");
+  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
+    rclcpp::CallbackGroupType::MutuallyExclusive);
+
+  entities_collector.add_callback_group(cb_group);
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  entities_collector.update_collections();
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  cb_group->get_associated_with_executor_atomic().exchange(false);
+  RCLCPP_EXPECT_THROW_EQ(
+    entities_collector.add_callback_group(cb_group),
+    std::runtime_error("Callback group has already been added to this executor."));
+}
+
+TEST_F(TestExecutorEntitiesCollector, remove_callback_group_after_node) {
+  auto notify_waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+  auto entities_collector = rclcpp::executors::ExecutorEntitiesCollector(notify_waitable);
+
+  auto node = std::make_shared<rclcpp::Node>("node1", "ns");
+  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
+    rclcpp::CallbackGroupType::MutuallyExclusive);
+
+  entities_collector.add_callback_group(cb_group);
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  entities_collector.update_collections();
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  node.reset();
+
+  /**
+   * TODO(mjcarroll): Assert this when we are enforcing that nodes must be destroyed
+   * after their created callback groups.
+  RCLCPP_EXPECT_THROW_EQ(
+    entities_collector.remove_callback_group(cb_group),
+    std::runtime_error("Node must not be deleted before its callback group(s)."));
+  */
+  EXPECT_NO_THROW(entities_collector.update_collections());
+}
+
+TEST_F(TestExecutorEntitiesCollector, remove_callback_group_after_node2) {
+  auto notify_waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+  auto entities_collector = rclcpp::executors::ExecutorEntitiesCollector(notify_waitable);
+
+  auto node = std::make_shared<rclcpp::Node>("node1", "ns");
+  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
+    rclcpp::CallbackGroupType::MutuallyExclusive);
+
+  entities_collector.add_callback_group(cb_group);
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 0u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  entities_collector.update_collections();
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  EXPECT_NO_THROW(entities_collector.remove_callback_group(cb_group));
+
+  node.reset();
+
+  /**
+   * TODO(mjcarroll): Assert this when we are enforcing that nodes must be destroyed
+   * after their created callback groups.
+  RCLCPP_EXPECT_THROW_EQ(
+    entities_collector.remove_callback_group(cb_group),
+    std::runtime_error("Node must not be deleted before its callback group(s)."));
+  */
+  EXPECT_NO_THROW(entities_collector.update_collections());
+}
+
+TEST_F(TestExecutorEntitiesCollector, remove_callback_group_twice) {
+  auto notify_waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+  auto entities_collector = rclcpp::executors::ExecutorEntitiesCollector(notify_waitable);
+
+  auto node = std::make_shared<rclcpp::Node>("node1", "ns");
+  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
+    rclcpp::CallbackGroupType::MutuallyExclusive);
+
+  entities_collector.add_callback_group(cb_group);
+  entities_collector.update_collections();
+
+  ASSERT_EQ(entities_collector.get_all_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_manually_added_callback_groups().size(), 1u);
+  ASSERT_EQ(entities_collector.get_automatically_added_callback_groups().size(), 0u);
+
+  entities_collector.remove_callback_group(cb_group);
+  entities_collector.update_collections();
+
+  RCLCPP_EXPECT_THROW_EQ(
+    entities_collector.remove_callback_group(cb_group),
+    std::runtime_error("Callback group needs to be associated with an executor."));
+}
+
+TEST_F(TestExecutorEntitiesCollector, remove_node_opposite_order) {
+  auto notify_waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+  auto entities_collector = rclcpp::executors::ExecutorEntitiesCollector(notify_waitable);
+
+  auto node1 = std::make_shared<rclcpp::Node>("node1", "ns");
+  EXPECT_NO_THROW(entities_collector.add_node(node1->get_node_base_interface()));
+
+  auto node2 = std::make_shared<rclcpp::Node>("node2", "ns");
+  EXPECT_NO_THROW(entities_collector.add_node(node2->get_node_base_interface()));
+
+  EXPECT_NO_THROW(entities_collector.remove_node(node2->get_node_base_interface()));
+}

rclcpp/test/rclcpp/executors/test_events_executor.cpp

@@ -0,0 +1,549 @@
+// Copyright 2023 iRobot Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <gtest/gtest.h>
+
+#include <chrono>
+#include <memory>
+#include <string>
+
+#include "rclcpp/experimental/executors/events_executor/events_executor.hpp"
+
+#include "test_msgs/srv/empty.hpp"
+#include "test_msgs/msg/empty.hpp"
+
+using namespace std::chrono_literals;
+
+using rclcpp::experimental::executors::EventsExecutor;
+
+class TestEventsExecutor : public ::testing::Test
+{
+public:
+  void SetUp()
+  {
+    rclcpp::init(0, nullptr);
+  }
+
+  void TearDown()
+  {
+    rclcpp::shutdown();
+  }
+};
+
+TEST_F(TestEventsExecutor, run_pub_sub)
+{
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  auto node = std::make_shared<rclcpp::Node>("node");
+
+  bool msg_received = false;
+  auto subscription = node->create_subscription<test_msgs::msg::Empty>(
+    "topic", rclcpp::SensorDataQoS(),
+    [&msg_received](test_msgs::msg::Empty::ConstSharedPtr msg)
+    {
+      (void)msg;
+      msg_received = true;
+    });
+
+  auto publisher = node->create_publisher<test_msgs::msg::Empty>("topic", rclcpp::SensorDataQoS());
+
+  EventsExecutor executor;
+  executor.add_node(node);
+
+  bool spin_exited = false;
+  std::thread spinner([&spin_exited, &executor, this]() {
+      executor.spin();
+      spin_exited = true;
+    });
+
+  auto msg = std::make_unique<test_msgs::msg::Empty>();
+  publisher->publish(std::move(msg));
+
+  // Wait some time for the subscription to receive the message
+  auto start = std::chrono::high_resolution_clock::now();
+  while (
+    !msg_received &&
+    !spin_exited &&
+    (std::chrono::high_resolution_clock::now() - start < 1s))
+  {
+    auto time = std::chrono::high_resolution_clock::now() - start;
+    auto time_msec = std::chrono::duration_cast<std::chrono::milliseconds>(time);
+    std::this_thread::sleep_for(25ms);
+  }
+
+  executor.cancel();
+  spinner.join();
+  executor.remove_node(node);
+
+  EXPECT_TRUE(msg_received);
+  EXPECT_TRUE(spin_exited);
+}
+
+TEST_F(TestEventsExecutor, run_clients_servers)
+{
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  auto node = std::make_shared<rclcpp::Node>("node");
+
+  bool request_received = false;
+  bool response_received = false;
+  auto service =
+    node->create_service<test_msgs::srv::Empty>(
+    "service",
+    [&request_received](
+      const test_msgs::srv::Empty::Request::SharedPtr,
+      test_msgs::srv::Empty::Response::SharedPtr)
+    {
+      request_received = true;
+    });
+  auto client = node->create_client<test_msgs::srv::Empty>("service");
+
+  EventsExecutor executor;
+  executor.add_node(node);
+
+  bool spin_exited = false;
+  std::thread spinner([&spin_exited, &executor, this]() {
+      executor.spin();
+      spin_exited = true;
+    });
+
+  auto request = std::make_shared<test_msgs::srv::Empty::Request>();
+  client->async_send_request(
+    request,
+    [&response_received](rclcpp::Client<test_msgs::srv::Empty>::SharedFuture result_future) {
+      (void)result_future;
+      response_received = true;
+    });
+
+  // Wait some time for the client-server to be invoked
+  auto start = std::chrono::steady_clock::now();
+  while (
+    !response_received &&
+    !spin_exited &&
+    (std::chrono::steady_clock::now() - start < 1s))
+  {
+    std::this_thread::sleep_for(5ms);
+  }
+
+  executor.cancel();
+  spinner.join();
+  executor.remove_node(node);
+
+  EXPECT_TRUE(request_received);
+  EXPECT_TRUE(response_received);
+  EXPECT_TRUE(spin_exited);
+}
+
+TEST_F(TestEventsExecutor, spin_once_max_duration_timeout)
+{
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  auto node = std::make_shared<rclcpp::Node>("node");
+
+  EventsExecutor executor;
+  executor.add_node(node);
+
+  // Consume previous events so we have a fresh start
+  executor.spin_all(1s);
+
+  size_t t_runs = 0;
+  auto t = node->create_wall_timer(
+    10s,
+    [&]() {
+      t_runs++;
+    });
+
+  // This first spin_once takes care of the waitable event
+  // generated by the addition of the timer to the node
+  executor.spin_once(1s);
+  EXPECT_EQ(0u, t_runs);
+
+  auto start = std::chrono::steady_clock::now();
+
+  // This second spin_once should take care of the timer,
+  executor.spin_once(10ms);
+
+  // but doesn't spin the time enough to call the timer callback.
+  EXPECT_EQ(0u, t_runs);
+  EXPECT_TRUE(std::chrono::steady_clock::now() - start < 200ms);
+}
+
+TEST_F(TestEventsExecutor, spin_once_max_duration_timer)
+{
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  auto node = std::make_shared<rclcpp::Node>("node");
+
+  EventsExecutor executor;
+  executor.add_node(node);
+
+  // Consume previous events so we have a fresh start
+  executor.spin_all(1s);
+
+  size_t t_runs = 0;
+  auto t = node->create_wall_timer(
+    10ms,
+    [&]() {
+      t_runs++;
+    });
+
+  // This first spin_once takes care of the waitable event
+  // generated by the addition of the timer to the node
+  executor.spin_once(1s);
+  EXPECT_EQ(0u, t_runs);
+
+  auto start = std::chrono::steady_clock::now();
+
+  // This second spin_once should take care of the timer
+  executor.spin_once(11ms);
+
+  EXPECT_EQ(1u, t_runs);
+  EXPECT_TRUE(std::chrono::steady_clock::now() - start < 200ms);
+}
+
+TEST_F(TestEventsExecutor, spin_some_max_duration)
+{
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  {
+    auto node = std::make_shared<rclcpp::Node>("node");
+
+    size_t t_runs = 0;
+    auto t = node->create_wall_timer(
+      10s,
+      [&]() {
+        t_runs++;
+      });
+
+    EventsExecutor executor;
+    executor.add_node(node);
+
+    auto start = std::chrono::steady_clock::now();
+    executor.spin_some(10ms);
+
+    EXPECT_EQ(0u, t_runs);
+    EXPECT_TRUE(std::chrono::steady_clock::now() - start < 200ms);
+  }
+
+  {
+    auto node = std::make_shared<rclcpp::Node>("node");
+
+    size_t t_runs = 0;
+    auto t = node->create_wall_timer(
+      10ms,
+      [&]() {
+        t_runs++;
+      });
+
+    // Sleep some time for the timer to be ready when spin
+    std::this_thread::sleep_for(10ms);
+
+    EventsExecutor executor;
+    executor.add_node(node);
+
+    auto start = std::chrono::steady_clock::now();
+    executor.spin_some(10s);
+
+    EXPECT_EQ(1u, t_runs);
+    EXPECT_TRUE(std::chrono::steady_clock::now() - start < 200ms);
+  }
+}
+
+TEST_F(TestEventsExecutor, spin_some_zero_duration)
+{
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  auto node = std::make_shared<rclcpp::Node>("node");
+
+  size_t t_runs = 0;
+  auto t = node->create_wall_timer(
+    20ms,
+    [&]() {
+      t_runs++;
+    });
+
+  // Sleep some time for the timer to be ready when spin
+  std::this_thread::sleep_for(20ms);
+
+  EventsExecutor executor;
+  executor.add_node(node);
+  executor.spin_some(0ms);
+
+  EXPECT_EQ(1u, t_runs);
+}
+
+TEST_F(TestEventsExecutor, spin_all_max_duration)
+{
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  {
+    auto node = std::make_shared<rclcpp::Node>("node");
+
+    size_t t_runs = 0;
+    auto t = node->create_wall_timer(
+      10s,
+      [&]() {
+        t_runs++;
+      });
+
+    EventsExecutor executor;
+    executor.add_node(node);
+
+    auto start = std::chrono::steady_clock::now();
+    executor.spin_all(10ms);
+
+    EXPECT_EQ(0u, t_runs);
+    EXPECT_TRUE(std::chrono::steady_clock::now() - start < 200ms);
+  }
+
+  {
+    auto node = std::make_shared<rclcpp::Node>("node");
+
+    size_t t_runs = 0;
+    auto t = node->create_wall_timer(
+      10ms,
+      [&]() {
+        t_runs++;
+      });
+
+    // Sleep some time for the timer to be ready when spin
+    std::this_thread::sleep_for(10ms);
+
+    EventsExecutor executor;
+    executor.add_node(node);
+
+    auto start = std::chrono::steady_clock::now();
+    executor.spin_all(10s);
+
+    EXPECT_EQ(1u, t_runs);
+    EXPECT_TRUE(std::chrono::steady_clock::now() - start < 200ms);
+  }
+
+  EventsExecutor executor;
+  EXPECT_THROW(executor.spin_all(0ms), std::invalid_argument);
+  EXPECT_THROW(executor.spin_all(-5ms), std::invalid_argument);
+}
+
+TEST_F(TestEventsExecutor, cancel_while_timers_running)
+{
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  auto node = std::make_shared<rclcpp::Node>("node");
+
+  EventsExecutor executor;
+  executor.add_node(node);
+
+  // Take care of previous events for a fresh start
+  executor.spin_all(1s);
+
+  size_t t1_runs = 0;
+  auto t1 = node->create_wall_timer(
+    1ms,
+    [&]() {
+      t1_runs++;
+      std::this_thread::sleep_for(50ms);
+    });
+
+  size_t t2_runs = 0;
+  auto t2 = node->create_wall_timer(
+    1ms,
+    [&]() {
+      t2_runs++;
+      std::this_thread::sleep_for(50ms);
+    });
+
+
+  std::thread spinner([&executor, this]() {executor.spin();});
+
+  std::this_thread::sleep_for(10ms);
+  // Call cancel while t1 callback is still being executed
+  executor.cancel();
+  spinner.join();
+
+  // Depending on the latency on the system, t2 may start to execute before cancel is signaled
+  EXPECT_GE(1u, t1_runs);
+  EXPECT_GE(1u, t2_runs);
+}
+
+TEST_F(TestEventsExecutor, cancel_while_timers_waiting)
+{
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  auto node = std::make_shared<rclcpp::Node>("node");
+
+  size_t t1_runs = 0;
+  auto t1 = node->create_wall_timer(
+    100s,
+    [&]() {
+      t1_runs++;
+    });
+
+  EventsExecutor executor;
+  executor.add_node(node);
+
+  auto start = std::chrono::steady_clock::now();
+  std::thread spinner([&executor, this]() {executor.spin();});
+
+  std::this_thread::sleep_for(10ms);
+  executor.cancel();
+  spinner.join();
+
+  EXPECT_EQ(0u, t1_runs);
+  EXPECT_TRUE(std::chrono::steady_clock::now() - start < 1s);
+}
+
+TEST_F(TestEventsExecutor, destroy_entities)
+{
+  // This test fails on Windows! We skip it for now
+  GTEST_SKIP();
+
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  // Create a publisher node and start publishing messages
+  auto node_pub = std::make_shared<rclcpp::Node>("node_pub");
+  auto publisher = node_pub->create_publisher<test_msgs::msg::Empty>("topic", rclcpp::QoS(10));
+  auto timer = node_pub->create_wall_timer(
+    2ms, [&]() {publisher->publish(std::make_unique<test_msgs::msg::Empty>());});
+  EventsExecutor executor_pub;
+  executor_pub.add_node(node_pub);
+  std::thread spinner([&executor_pub, this]() {executor_pub.spin();});
+
+  // Create a node with two different subscriptions to the topic
+  auto node_sub = std::make_shared<rclcpp::Node>("node_sub");
+  size_t callback_count_1 = 0;
+  auto subscription_1 =
+    node_sub->create_subscription<test_msgs::msg::Empty>(
+    "topic", rclcpp::QoS(10), [&](test_msgs::msg::Empty::ConstSharedPtr) {callback_count_1++;});
+  size_t callback_count_2 = 0;
+  auto subscription_2 =
+    node_sub->create_subscription<test_msgs::msg::Empty>(
+    "topic", rclcpp::QoS(10), [&](test_msgs::msg::Empty::ConstSharedPtr) {callback_count_2++;});
+  EventsExecutor executor_sub;
+  executor_sub.add_node(node_sub);
+
+  // Wait some time while messages are published
+  std::this_thread::sleep_for(10ms);
+
+  // Destroy one of the two subscriptions
+  subscription_1.reset();
+
+  // Let subscriptions executor spin
+  executor_sub.spin_some(10ms);
+
+  // The callback count of the destroyed subscription remained at 0
+  EXPECT_EQ(0u, callback_count_1);
+  EXPECT_LT(0u, callback_count_2);
+
+  executor_pub.cancel();
+  spinner.join();
+}
+
+// Testing construction of a subscriptions with QoS event callback functions.
+std::string * g_pub_log_msg;
+std::string * g_sub_log_msg;
+std::promise<void> * g_log_msgs_promise;
+TEST_F(TestEventsExecutor, test_default_incompatible_qos_callbacks)
+{
+  // rmw_connextdds doesn't support events-executor
+  if (std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0) {
+    GTEST_SKIP();
+  }
+
+  auto node = std::make_shared<rclcpp::Node>("node");
+  rcutils_logging_output_handler_t original_output_handler = rcutils_logging_get_output_handler();
+
+  std::string pub_log_msg;
+  std::string sub_log_msg;
+  std::promise<void> log_msgs_promise;
+  g_pub_log_msg = &pub_log_msg;
+  g_sub_log_msg = &sub_log_msg;
+  g_log_msgs_promise = &log_msgs_promise;
+  auto logger_callback = [](
+    const rcutils_log_location_t * /*location*/,
+    int /*level*/, const char * /*name*/, rcutils_time_point_value_t /*timestamp*/,
+    const char * format, va_list * args) -> void {
+      char buffer[1024];
+      vsnprintf(buffer, sizeof(buffer), format, *args);
+      const std::string msg = buffer;
+      if (msg.rfind("New subscription discovered on topic '/test_topic'", 0) == 0) {
+        *g_pub_log_msg = buffer;
+      } else if (msg.rfind("New publisher discovered on topic '/test_topic'", 0) == 0) {
+        *g_sub_log_msg = buffer;
+      }
+
+      if (!g_pub_log_msg->empty() && !g_sub_log_msg->empty()) {
+        g_log_msgs_promise->set_value();
+      }
+    };
+  rcutils_logging_set_output_handler(logger_callback);
+
+  std::shared_future<void> log_msgs_future = log_msgs_promise.get_future();
+
+  rclcpp::QoS qos_profile_publisher(10);
+  qos_profile_publisher.durability(RMW_QOS_POLICY_DURABILITY_VOLATILE);
+  auto publisher = node->create_publisher<test_msgs::msg::Empty>(
+    "test_topic", qos_profile_publisher);
+
+  rclcpp::QoS qos_profile_subscription(10);
+  qos_profile_subscription.durability(RMW_QOS_POLICY_DURABILITY_TRANSIENT_LOCAL);
+  auto subscription = node->create_subscription<test_msgs::msg::Empty>(
+    "test_topic", qos_profile_subscription, [&](test_msgs::msg::Empty::ConstSharedPtr) {});
+
+  EventsExecutor ex;
+  ex.add_node(node->get_node_base_interface());
+
+  const auto timeout = std::chrono::seconds(10);
+  ex.spin_until_future_complete(log_msgs_future, timeout);
+
+  EXPECT_EQ(
+    "New subscription discovered on topic '/test_topic', requesting incompatible QoS. "
+    "No messages will be sent to it. Last incompatible policy: DURABILITY_QOS_POLICY",
+    pub_log_msg);
+  EXPECT_EQ(
+    "New publisher discovered on topic '/test_topic', offering incompatible QoS. "
+    "No messages will be sent to it. Last incompatible policy: DURABILITY_QOS_POLICY",
+    sub_log_msg);
+
+  rcutils_logging_set_output_handler(original_output_handler);
+}

rclcpp/test/rclcpp/executors/test_events_queue.cpp

@@ -0,0 +1,82 @@
+// Copyright 2023 iRobot Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <gtest/gtest.h>
+
+#include <memory>
+
+#include "rclcpp/experimental/executors/events_executor/events_executor_event_types.hpp"
+#include "rclcpp/experimental/executors/events_executor/simple_events_queue.hpp"
+
+using namespace std::chrono_literals;
+
+TEST(TestEventsQueue, SimpleQueueTest)
+{
+  // Create a SimpleEventsQueue and a local queue
+  auto simple_queue = std::make_unique<rclcpp::experimental::executors::SimpleEventsQueue>();
+  rclcpp::experimental::executors::ExecutorEvent event {};
+  bool ret = false;
+
+  // Make sure the queue is empty at startup
+  EXPECT_TRUE(simple_queue->empty());
+  EXPECT_EQ(simple_queue->size(), 0u);
+
+  // Push 11 messages
+  for (uint32_t i = 1; i < 11; i++) {
+    rclcpp::experimental::executors::ExecutorEvent stub_event {};
+    stub_event.num_events = 1;
+    simple_queue->enqueue(stub_event);
+
+    EXPECT_FALSE(simple_queue->empty());
+    EXPECT_EQ(simple_queue->size(), i);
+  }
+
+  // Pop one message
+  ret = simple_queue->dequeue(event);
+  EXPECT_TRUE(ret);
+  EXPECT_FALSE(simple_queue->empty());
+  EXPECT_EQ(simple_queue->size(), 9u);
+
+  // Pop one message
+  ret = simple_queue->dequeue(event, std::chrono::nanoseconds(0));
+  EXPECT_TRUE(ret);
+  EXPECT_FALSE(simple_queue->empty());
+  EXPECT_EQ(simple_queue->size(), 8u);
+
+  while (!simple_queue->empty()) {
+    ret = simple_queue->dequeue(event);
+    EXPECT_TRUE(ret);
+  }
+
+  EXPECT_TRUE(simple_queue->empty());
+  EXPECT_EQ(simple_queue->size(), 0u);
+
+  ret = simple_queue->dequeue(event, std::chrono::nanoseconds(0));
+  EXPECT_FALSE(ret);
+
+  // Lets push an event into the queue and get it back
+  rclcpp::experimental::executors::ExecutorEvent push_event = {
+    simple_queue.get(),
+    99,
+    rclcpp::experimental::executors::ExecutorEventType::SUBSCRIPTION_EVENT,
+    1};
+
+  simple_queue->enqueue(push_event);
+  ret = simple_queue->dequeue(event);
+  EXPECT_TRUE(ret);
+  EXPECT_EQ(push_event.entity_key, event.entity_key);
+  EXPECT_EQ(push_event.waitable_data, event.waitable_data);
+  EXPECT_EQ(push_event.type, event.type);
+  EXPECT_EQ(push_event.num_events, event.num_events);
+}

rclcpp/test/rclcpp/executors/test_executor_notify_waitable.cpp

@@ -0,0 +1,97 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <gtest/gtest.h>
+
+#include <chrono>
+#include <memory>
+#include <stdexcept>
+
+#include "rclcpp/executors/single_threaded_executor.hpp"
+#include "rclcpp/rclcpp.hpp"
+
+#include "rcpputils/scope_exit.hpp"
+
+#include "rclcpp/executors/executor_notify_waitable.hpp"
+
+#include "../../utils/rclcpp_gtest_macros.hpp"
+
+
+class TestExecutorNotifyWaitable : public ::testing::Test
+{
+public:
+  void SetUp()
+  {
+    rclcpp::init(0, nullptr);
+  }
+
+  void TearDown()
+  {
+    rclcpp::shutdown();
+  }
+};
+
+TEST_F(TestExecutorNotifyWaitable, construct_destruct) {
+  {
+    auto waitable = std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>();
+    waitable.reset();
+  }
+  {
+    auto on_execute_callback = []() {};
+    auto waitable =
+      std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>(on_execute_callback);
+    waitable.reset();
+  }
+}
+
+TEST_F(TestExecutorNotifyWaitable, add_remove_guard_conditions) {
+  auto on_execute_callback = []() {};
+  auto waitable =
+    std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>(on_execute_callback);
+
+  auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
+  auto notify_guard_condition =
+
+    node->get_node_base_interface()->get_shared_notify_guard_condition();
+  EXPECT_NO_THROW(waitable->add_guard_condition(notify_guard_condition));
+  EXPECT_NO_THROW(waitable->remove_guard_condition(notify_guard_condition));
+}
+
+TEST_F(TestExecutorNotifyWaitable, wait) {
+  int on_execute_calls = 0;
+  auto on_execute_callback = [&on_execute_calls]() {on_execute_calls++;};
+
+  auto waitable =
+    std::make_shared<rclcpp::executors::ExecutorNotifyWaitable>(on_execute_callback);
+
+  auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
+  auto notify_guard_condition =
+    node->get_node_base_interface()->get_shared_notify_guard_condition();
+  EXPECT_NO_THROW(waitable->add_guard_condition(notify_guard_condition));
+
+  auto default_cbg = node->get_node_base_interface()->get_default_callback_group();
+  ASSERT_NE(nullptr, default_cbg->get_notify_guard_condition());
+
+  auto waitables = node->get_node_waitables_interface();
+  waitables->add_waitable(std::static_pointer_cast<rclcpp::Waitable>(waitable), default_cbg);
+
+  rclcpp::executors::SingleThreadedExecutor executor;
+  executor.add_node(node);
+  executor.spin_all(std::chrono::seconds(1));
+  EXPECT_EQ(1u, on_execute_calls);
+
+  // on_execute_callback doesn't change if the topology doesn't change
+  executor.spin_all(std::chrono::seconds(1));
+  EXPECT_EQ(1u, on_execute_calls);
+}

rclcpp/test/rclcpp/executors/test_executors.cpp

@@ -83,8 +83,6 @@ public:
   int callback_count;
 };
 
-// spin_all and spin_some are not implemented correctly in StaticSingleThreadedExecutor, see:
-// https://github.com/ros2/rclcpp/issues/1219 for tracking
 template<typename T>
 class TestExecutorsStable : public TestExecutors<T> {};
 
@@ -92,7 +90,8 @@ using ExecutorTypes =
   ::testing::Types<
   rclcpp::executors::SingleThreadedExecutor,
   rclcpp::executors::MultiThreadedExecutor,
-  rclcpp::executors::StaticSingleThreadedExecutor>;
+  rclcpp::executors::StaticSingleThreadedExecutor,
+  rclcpp::experimental::executors::EventsExecutor>;
 
 class ExecutorTypeNames
 {
@@ -113,6 +112,10 @@ public:
       return "StaticSingleThreadedExecutor";
     }
 
+    if (std::is_same<T, rclcpp::experimental::executors::EventsExecutor>()) {
+      return "EventsExecutor";
+    }
+
     return "";
   }
 };
@@ -121,17 +124,18 @@ public:
 // is updated.
 TYPED_TEST_SUITE(TestExecutors, ExecutorTypes, ExecutorTypeNames);
 
-// StaticSingleThreadedExecutor is not included in these tests for now, due to:
-// https://github.com/ros2/rclcpp/issues/1219
-using StandardExecutors =
-  ::testing::Types<
-  rclcpp::executors::SingleThreadedExecutor,
-  rclcpp::executors::MultiThreadedExecutor>;
-TYPED_TEST_SUITE(TestExecutorsStable, StandardExecutors, ExecutorTypeNames);
-
 // Make sure that executors detach from nodes when destructing
-TYPED_TEST(TestExecutors, detachOnDestruction) {
+TYPED_TEST(TestExecutors, detachOnDestruction)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   {
     ExecutorType executor;
     executor.add_node(this->node);
@@ -143,10 +147,16 @@ TYPED_TEST(TestExecutors, detachOnDestruction) {
 }
 
 // Make sure that the executor can automatically remove expired nodes correctly
-// Currently fails for StaticSingleThreadedExecutor so it is being skipped, see:
-// https://github.com/ros2/rclcpp/issues/1231
-TYPED_TEST(TestExecutorsStable, addTemporaryNode) {
+TYPED_TEST(TestExecutors, addTemporaryNode) {
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
 
   {
@@ -163,9 +173,37 @@ TYPED_TEST(TestExecutorsStable, addTemporaryNode) {
   spinner.join();
 }
 
-// Check executor throws properly if the same node is added a second time
-TYPED_TEST(TestExecutors, addNodeTwoExecutors) {
+// Make sure that a spinning empty executor can be cancelled
+TYPED_TEST(TestExecutors, emptyExecutor)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
+  ExecutorType executor;
+  std::thread spinner([&]() {EXPECT_NO_THROW(executor.spin());});
+  std::this_thread::sleep_for(50ms);
+  executor.cancel();
+  spinner.join();
+}
+
+// Check executor throws properly if the same node is added a second time
+TYPED_TEST(TestExecutors, addNodeTwoExecutors)
+{
+  using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor1;
   ExecutorType executor2;
   EXPECT_NO_THROW(executor1.add_node(this->node));
@@ -174,8 +212,17 @@ TYPED_TEST(TestExecutors, addNodeTwoExecutors) {
 }
 
 // Check simple spin example
-TYPED_TEST(TestExecutors, spinWithTimer) {
+TYPED_TEST(TestExecutors, spinWithTimer)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
 
   bool timer_completed = false;
@@ -196,19 +243,31 @@ TYPED_TEST(TestExecutors, spinWithTimer) {
   executor.remove_node(this->node, true);
 }
 
-TYPED_TEST(TestExecutors, spinWhileAlreadySpinning) {
+TYPED_TEST(TestExecutors, spinWhileAlreadySpinning)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
   executor.add_node(this->node);
 
-  bool timer_completed = false;
-  auto timer = this->node->create_wall_timer(1ms, [&]() {timer_completed = true;});
+  std::atomic_bool timer_completed = false;
+  auto timer = this->node->create_wall_timer(
+    1ms, [&]() {
+      timer_completed.store(true);
+    });
 
   std::thread spinner([&]() {executor.spin();});
   // Sleep for a short time to verify executor.spin() is going, and didn't throw.
 
   auto start = std::chrono::steady_clock::now();
-  while (!timer_completed && (std::chrono::steady_clock::now() - start) < 10s) {
+  while (!timer_completed.load() && (std::chrono::steady_clock::now() - start) < 10s) {
     std::this_thread::sleep_for(1ms);
   }
 
@@ -222,8 +281,17 @@ TYPED_TEST(TestExecutors, spinWhileAlreadySpinning) {
 }
 
 // Check executor exits immediately if future is complete.
-TYPED_TEST(TestExecutors, testSpinUntilFutureComplete) {
+TYPED_TEST(TestExecutors, testSpinUntilFutureComplete)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
   executor.add_node(this->node);
 
@@ -244,8 +312,17 @@ TYPED_TEST(TestExecutors, testSpinUntilFutureComplete) {
 }
 
 // Same test, but uses a shared future.
-TYPED_TEST(TestExecutors, testSpinUntilSharedFutureComplete) {
+TYPED_TEST(TestExecutors, testSpinUntilSharedFutureComplete)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
   executor.add_node(this->node);
 
@@ -267,8 +344,17 @@ TYPED_TEST(TestExecutors, testSpinUntilSharedFutureComplete) {
 }
 
 // For a longer running future that should require several iterations of spin_once
-TYPED_TEST(TestExecutors, testSpinUntilFutureCompleteNoTimeout) {
+TYPED_TEST(TestExecutors, testSpinUntilFutureCompleteNoTimeout)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
   executor.add_node(this->node);
 
@@ -313,8 +399,17 @@ TYPED_TEST(TestExecutors, testSpinUntilFutureCompleteNoTimeout) {
 }
 
 // Check spin_until_future_complete timeout works as expected
-TYPED_TEST(TestExecutors, testSpinUntilFutureCompleteWithTimeout) {
+TYPED_TEST(TestExecutors, testSpinUntilFutureCompleteWithTimeout)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
   executor.add_node(this->node);
 
@@ -380,6 +475,13 @@ public:
     return nullptr;
   }
 
+  std::shared_ptr<void>
+  take_data_by_entity_id(size_t id) override
+  {
+    (void) id;
+    return nullptr;
+  }
+
   void
   execute(std::shared_ptr<void> & data) override
   {
@@ -388,6 +490,21 @@ public:
     std::this_thread::sleep_for(3ms);
   }
 
+  void
+  set_on_ready_callback(std::function<void(size_t, int)> callback) override
+  {
+    auto gc_callback = [callback](size_t count) {
+        callback(count, 0);
+      };
+    gc_.set_on_trigger_callback(gc_callback);
+  }
+
+  void
+  clear_on_ready_callback() override
+  {
+    gc_.set_on_trigger_callback(nullptr);
+  }
+
   size_t
   get_number_of_ready_guard_conditions() override {return 1;}
 
@@ -402,8 +519,17 @@ private:
   rclcpp::GuardCondition gc_;
 };
 
-TYPED_TEST(TestExecutors, spinAll) {
+TYPED_TEST(TestExecutors, spinAll)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
   auto waitable_interfaces = this->node->get_node_waitables_interface();
   auto my_waitable = std::make_shared<TestWaitable>();
@@ -443,8 +569,17 @@ TYPED_TEST(TestExecutors, spinAll) {
   spinner.join();
 }
 
-TYPED_TEST(TestExecutors, spinSome) {
+TYPED_TEST(TestExecutors, spinSome)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
   auto waitable_interfaces = this->node->get_node_waitables_interface();
   auto my_waitable = std::make_shared<TestWaitable>();
@@ -472,8 +607,9 @@ TYPED_TEST(TestExecutors, spinSome) {
     this->publisher->publish(test_msgs::msg::Empty());
     std::this_thread::sleep_for(1ms);
   }
-
-  EXPECT_EQ(1u, my_waitable->get_count());
+  // The count of "execute" depends on whether the executor starts spinning before (1) or after (0)
+  // the first iteration of the while loop
+  EXPECT_LE(1u, my_waitable->get_count());
   waitable_interfaces->remove_waitable(my_waitable, nullptr);
   EXPECT_TRUE(spin_exited);
   // Cancel if it hasn't exited already.
@@ -483,8 +619,17 @@ TYPED_TEST(TestExecutors, spinSome) {
 }
 
 // Check spin_node_until_future_complete with node base pointer
-TYPED_TEST(TestExecutors, testSpinNodeUntilFutureCompleteNodeBasePtr) {
+TYPED_TEST(TestExecutors, testSpinNodeUntilFutureCompleteNodeBasePtr)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
 
   std::promise<bool> promise;
@@ -498,8 +643,17 @@ TYPED_TEST(TestExecutors, testSpinNodeUntilFutureCompleteNodeBasePtr) {
 }
 
 // Check spin_node_until_future_complete with node pointer
-TYPED_TEST(TestExecutors, testSpinNodeUntilFutureCompleteNodePtr) {
+TYPED_TEST(TestExecutors, testSpinNodeUntilFutureCompleteNodePtr)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
 
   std::promise<bool> promise;
@@ -513,8 +667,17 @@ TYPED_TEST(TestExecutors, testSpinNodeUntilFutureCompleteNodePtr) {
 }
 
 // Check spin_until_future_complete can be properly interrupted.
-TYPED_TEST(TestExecutors, testSpinUntilFutureCompleteInterrupted) {
+TYPED_TEST(TestExecutors, testSpinUntilFutureCompleteInterrupted)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   ExecutorType executor;
   executor.add_node(this->node);
 
@@ -556,7 +719,8 @@ TYPED_TEST(TestExecutors, testSpinUntilFutureCompleteInterrupted) {
 }
 
 // Check spin_until_future_complete with node base pointer (instantiates its own executor)
-TEST(TestExecutors, testSpinUntilFutureCompleteNodeBasePtr) {
+TEST(TestExecutors, testSpinUntilFutureCompleteNodeBasePtr)
+{
   rclcpp::init(0, nullptr);
 
   {
@@ -576,7 +740,8 @@ TEST(TestExecutors, testSpinUntilFutureCompleteNodeBasePtr) {
 }
 
 // Check spin_until_future_complete with node pointer (instantiates its own executor)
-TEST(TestExecutors, testSpinUntilFutureCompleteNodePtr) {
+TEST(TestExecutors, testSpinUntilFutureCompleteNodePtr)
+{
   rclcpp::init(0, nullptr);
 
   {
@@ -593,3 +758,106 @@ TEST(TestExecutors, testSpinUntilFutureCompleteNodePtr) {
 
   rclcpp::shutdown();
 }
+
+template<typename T>
+class TestIntraprocessExecutors : public ::testing::Test
+{
+public:
+  static void SetUpTestCase()
+  {
+    rclcpp::init(0, nullptr);
+  }
+
+  static void TearDownTestCase()
+  {
+    rclcpp::shutdown();
+  }
+
+  void SetUp()
+  {
+    const auto test_info = ::testing::UnitTest::GetInstance()->current_test_info();
+    std::stringstream test_name;
+    test_name << test_info->test_case_name() << "_" << test_info->name();
+    node = std::make_shared<rclcpp::Node>("node", test_name.str());
+
+    callback_count = 0;
+
+    const std::string topic_name = std::string("topic_") + test_name.str();
+
+    rclcpp::PublisherOptions po;
+    po.use_intra_process_comm = rclcpp::IntraProcessSetting::Enable;
+    publisher = node->create_publisher<test_msgs::msg::Empty>(topic_name, rclcpp::QoS(1), po);
+
+    auto callback = [this](test_msgs::msg::Empty::ConstSharedPtr) {
+        this->callback_count.fetch_add(1);
+      };
+
+    rclcpp::SubscriptionOptions so;
+    so.use_intra_process_comm = rclcpp::IntraProcessSetting::Enable;
+    subscription =
+      node->create_subscription<test_msgs::msg::Empty>(
+      topic_name, rclcpp::QoS(kNumMessages), std::move(callback), so);
+  }
+
+  void TearDown()
+  {
+    publisher.reset();
+    subscription.reset();
+    node.reset();
+  }
+
+  const size_t kNumMessages = 100;
+
+  rclcpp::Node::SharedPtr node;
+  rclcpp::Publisher<test_msgs::msg::Empty>::SharedPtr publisher;
+  rclcpp::Subscription<test_msgs::msg::Empty>::SharedPtr subscription;
+  std::atomic_int callback_count;
+};
+
+TYPED_TEST_SUITE(TestIntraprocessExecutors, ExecutorTypes, ExecutorTypeNames);
+
+TYPED_TEST(TestIntraprocessExecutors, testIntraprocessRetrigger) {
+  // This tests that executors will continue to service intraprocess subscriptions in the case
+  // that publishers aren't continuing to publish.
+  // This was previously broken in that intraprocess guard conditions were only triggered on
+  // publish and the test was added to prevent future regressions.
+  const size_t kNumMessages = 100;
+
+  using ExecutorType = TypeParam;
+  ExecutorType executor;
+  executor.add_node(this->node);
+
+  EXPECT_EQ(0, this->callback_count.load());
+  this->publisher->publish(test_msgs::msg::Empty());
+
+  // Wait for up to 5 seconds for the first message to come available.
+  const std::chrono::milliseconds sleep_per_loop(10);
+  int loops = 0;
+  while (1u != this->callback_count.load() && loops < 500) {
+    rclcpp::sleep_for(sleep_per_loop);
+    executor.spin_some();
+    loops++;
+  }
+  EXPECT_EQ(1u, this->callback_count.load());
+
+  // reset counter
+  this->callback_count.store(0);
+
+  for (size_t ii = 0; ii < kNumMessages; ++ii) {
+    this->publisher->publish(test_msgs::msg::Empty());
+  }
+
+  // Fire a timer every 10ms up to 5 seconds waiting for subscriptions to be read.
+  loops = 0;
+  auto timer = this->node->create_wall_timer(
+    std::chrono::milliseconds(10), [this, &executor, &loops, &kNumMessages]() {
+      loops++;
+      if (kNumMessages == this->callback_count.load() ||
+      loops == 500)
+      {
+        executor.cancel();
+      }
+    });
+  executor.spin();
+  EXPECT_EQ(kNumMessages, this->callback_count.load());
+}

rclcpp/test/rclcpp/node_interfaces/test_node_graph.cpp

@@ -28,6 +28,7 @@
 #include "rclcpp/node_interfaces/node_graph.hpp"
 #include "rclcpp/rclcpp.hpp"
 #include "rcutils/strdup.h"
+#include "test_msgs/msg/empty.h"
 #include "test_msgs/msg/empty.hpp"
 #include "test_msgs/srv/empty.hpp"
 
@@ -599,6 +600,18 @@ TEST_F(TestNodeGraph, get_info_by_topic)
   rclcpp::QoS const_actual_qos = const_publisher_endpoint_info.qos_profile();
   EXPECT_EQ(const_actual_qos.reliability(), rclcpp::ReliabilityPolicy::Reliable);
 
+  const rosidl_type_hash_t expected_type_hash = *test_msgs__msg__Empty__get_type_hash(nullptr);
+  EXPECT_EQ(
+    0, memcmp(
+      &publisher_endpoint_info.topic_type_hash(),
+      &expected_type_hash,
+      sizeof(rosidl_type_hash_t)));
+  EXPECT_EQ(
+    0, memcmp(
+      &const_publisher_endpoint_info.topic_type_hash(),
+      &expected_type_hash,
+      sizeof(rosidl_type_hash_t)));
+
   auto endpoint_gid = publisher_endpoint_info.endpoint_gid();
   auto const_endpoint_gid = const_publisher_endpoint_info.endpoint_gid();
   bool endpoint_gid_is_all_zeros = true;

rclcpp/test/rclcpp/node_interfaces/test_node_topics.cpp

@@ -28,6 +28,11 @@
 #include "../../mocking_utils/patch.hpp"
 #include "../../utils/rclcpp_gtest_macros.hpp"
 
+using rclcpp::dynamic_typesupport::DynamicMessage;
+using rclcpp::dynamic_typesupport::DynamicMessageType;
+using rclcpp::dynamic_typesupport::DynamicSerializationSupport;
+
+
 namespace
 {
 
@@ -77,6 +82,18 @@ public:
     const std::shared_ptr<rclcpp::SerializedMessage> &, const rclcpp::MessageInfo &) override {}
   void return_message(std::shared_ptr<void> &) override {}
   void return_serialized_message(std::shared_ptr<rclcpp::SerializedMessage> &) override {}
+
+  DynamicMessageType::SharedPtr get_shared_dynamic_message_type() override {return nullptr;}
+  DynamicMessage::SharedPtr get_shared_dynamic_message() override {return nullptr;}
+  DynamicSerializationSupport::SharedPtr get_shared_dynamic_serialization_support() override
+  {
+    return nullptr;
+  }
+  DynamicMessage::SharedPtr create_dynamic_message() override {return nullptr;}
+  void return_dynamic_message(DynamicMessage::SharedPtr &) override {}
+  void handle_dynamic_message(
+    const DynamicMessage::SharedPtr &,
+    const rclcpp::MessageInfo &) override {}
 };
 
 class TestNodeTopics : public ::testing::Test

rclcpp/test/rclcpp/test_add_callback_groups_to_executor.cpp

@@ -46,11 +46,15 @@ public:
   }
 };
 
+template<typename T>
+class TestAddCallbackGroupsToExecutorStable : public TestAddCallbackGroupsToExecutor<T> {};
+
 using ExecutorTypes =
   ::testing::Types<
   rclcpp::executors::SingleThreadedExecutor,
   rclcpp::executors::MultiThreadedExecutor,
-  rclcpp::executors::StaticSingleThreadedExecutor>;
+  rclcpp::executors::StaticSingleThreadedExecutor,
+  rclcpp::experimental::executors::EventsExecutor>;
 
 class ExecutorTypeNames
 {
@@ -71,17 +75,38 @@ public:
       return "StaticSingleThreadedExecutor";
     }
 
+    if (std::is_same<T, rclcpp::experimental::executors::EventsExecutor>()) {
+      return "EventsExecutor";
+    }
+
     return "";
   }
 };
 
 TYPED_TEST_SUITE(TestAddCallbackGroupsToExecutor, ExecutorTypes, ExecutorTypeNames);
 
+// StaticSingleThreadedExecutor is not included in these tests for now
+using StandardExecutors =
+  ::testing::Types<
+  rclcpp::executors::SingleThreadedExecutor,
+  rclcpp::executors::MultiThreadedExecutor,
+  rclcpp::experimental::executors::EventsExecutor>;
+TYPED_TEST_SUITE(TestAddCallbackGroupsToExecutorStable, StandardExecutors, ExecutorTypeNames);
+
 /*
  * Test adding callback groups.
  */
-TYPED_TEST(TestAddCallbackGroupsToExecutor, add_callback_groups) {
+TYPED_TEST(TestAddCallbackGroupsToExecutor, add_callback_groups)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
   auto timer_callback = []() {};
   rclcpp::CallbackGroup::SharedPtr cb_grp = node->create_callback_group(
@@ -127,8 +152,17 @@ TYPED_TEST(TestAddCallbackGroupsToExecutor, add_callback_groups) {
 /*
  * Test removing callback groups.
  */
-TYPED_TEST(TestAddCallbackGroupsToExecutor, remove_callback_groups) {
+TYPED_TEST(TestAddCallbackGroupsToExecutor, remove_callback_groups)
+{
   using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
   auto timer_callback = []() {};
   rclcpp::CallbackGroup::SharedPtr cb_grp = node->create_callback_group(
@@ -158,7 +192,16 @@ TYPED_TEST(TestAddCallbackGroupsToExecutor, remove_callback_groups) {
  */
 TYPED_TEST(TestAddCallbackGroupsToExecutor, add_duplicate_callback_groups)
 {
-  rclcpp::executors::MultiThreadedExecutor executor;
+  using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
+  ExecutorType executor;
   auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
   auto timer_callback = []() {};
   rclcpp::CallbackGroup::SharedPtr cb_grp = node->create_callback_group(
@@ -176,7 +219,16 @@ TYPED_TEST(TestAddCallbackGroupsToExecutor, add_duplicate_callback_groups)
  */
 TYPED_TEST(TestAddCallbackGroupsToExecutor, add_callback_groups_after_add_node_to_executor)
 {
-  rclcpp::executors::MultiThreadedExecutor executor;
+  using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
+  ExecutorType executor;
   auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
   executor.add_node(node->get_node_base_interface());
   ASSERT_EQ(executor.get_all_callback_groups().size(), 1u);
@@ -210,13 +262,22 @@ TYPED_TEST(TestAddCallbackGroupsToExecutor, add_callback_groups_after_add_node_t
  */
 TYPED_TEST(TestAddCallbackGroupsToExecutor, add_unallowable_callback_groups)
 {
+  using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
+  ExecutorType executor;
   auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
   auto timer_callback = []() {};
   rclcpp::CallbackGroup::SharedPtr cb_grp = node->create_callback_group(
     rclcpp::CallbackGroupType::MutuallyExclusive, false);
   rclcpp::TimerBase::SharedPtr timer_ = node->create_wall_timer(
     2s, timer_callback, cb_grp);
-  rclcpp::executors::MultiThreadedExecutor executor;
   executor.add_callback_group(cb_grp, node->get_node_base_interface());
   ASSERT_EQ(executor.get_all_callback_groups().size(), 1u);
 
@@ -245,14 +306,23 @@ TYPED_TEST(TestAddCallbackGroupsToExecutor, add_unallowable_callback_groups)
  */
 TYPED_TEST(TestAddCallbackGroupsToExecutor, one_node_many_callback_groups_many_executors)
 {
+  using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
+  ExecutorType timer_executor;
+  ExecutorType sub_executor;
   auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
   auto timer_callback = []() {};
   rclcpp::CallbackGroup::SharedPtr cb_grp = node->create_callback_group(
     rclcpp::CallbackGroupType::MutuallyExclusive, false);
   rclcpp::TimerBase::SharedPtr timer_ = node->create_wall_timer(
     2s, timer_callback, cb_grp);
-  rclcpp::executors::MultiThreadedExecutor timer_executor;
-  rclcpp::executors::MultiThreadedExecutor sub_executor;
   timer_executor.add_callback_group(cb_grp, node->get_node_base_interface());
   const rclcpp::QoS qos(10);
   auto options = rclcpp::SubscriptionOptions();
@@ -282,14 +352,23 @@ TYPED_TEST(TestAddCallbackGroupsToExecutor, one_node_many_callback_groups_many_e
  * because the executor can't be triggered while a subscriber created, see
  * https://github.com/ros2/rclcpp/issues/1611
 */
-TYPED_TEST(TestAddCallbackGroupsToExecutor, subscriber_triggered_to_receive_message)
+TYPED_TEST(TestAddCallbackGroupsToExecutorStable, subscriber_triggered_to_receive_message)
 {
+  using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
 
   // create a thread running an executor with a new callback group for a coming subscriber
   rclcpp::CallbackGroup::SharedPtr cb_grp = node->create_callback_group(
     rclcpp::CallbackGroupType::MutuallyExclusive, false);
-  rclcpp::executors::SingleThreadedExecutor cb_grp_executor;
+  ExecutorType cb_grp_executor;
 
   std::promise<bool> received_message_promise;
   auto received_message_future = received_message_promise.get_future();
@@ -329,7 +408,7 @@ TYPED_TEST(TestAddCallbackGroupsToExecutor, subscriber_triggered_to_receive_mess
       timer_promise.set_value();
     };
 
-  rclcpp::executors::SingleThreadedExecutor timer_executor;
+  ExecutorType timer_executor;
   timer = node->create_wall_timer(100ms, timer_callback);
   timer_executor.add_node(node);
   auto future = timer_promise.get_future();
@@ -346,8 +425,17 @@ TYPED_TEST(TestAddCallbackGroupsToExecutor, subscriber_triggered_to_receive_mess
  * because the executor can't be triggered while a subscriber created, see
  * https://github.com/ros2/rclcpp/issues/2067
 */
-TYPED_TEST(TestAddCallbackGroupsToExecutor, callback_group_create_after_spin)
+TYPED_TEST(TestAddCallbackGroupsToExecutorStable, callback_group_create_after_spin)
 {
+  using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
   auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
 
   // create a publisher to send data
@@ -357,7 +445,7 @@ TYPED_TEST(TestAddCallbackGroupsToExecutor, callback_group_create_after_spin)
   publisher->publish(test_msgs::msg::Empty());
 
   // create a thread running an executor
-  rclcpp::executors::SingleThreadedExecutor executor;
+  ExecutorType executor;
   executor.add_node(node);
   std::promise<bool> received_message_promise;
   auto received_message_future = received_message_promise.get_future();
@@ -392,7 +480,16 @@ TYPED_TEST(TestAddCallbackGroupsToExecutor, callback_group_create_after_spin)
  */
 TYPED_TEST(TestAddCallbackGroupsToExecutor, remove_callback_group)
 {
-  rclcpp::executors::MultiThreadedExecutor executor;
+  using ExecutorType = TypeParam;
+  // rmw_connextdds doesn't support events-executor
+  if (
+    std::is_same<ExecutorType, rclcpp::experimental::executors::EventsExecutor>() &&
+    std::string(rmw_get_implementation_identifier()).find("rmw_connextdds") == 0)
+  {
+    GTEST_SKIP();
+  }
+
+  ExecutorType executor;
   auto node = std::make_shared<rclcpp::Node>("my_node", "/ns");
   auto timer_callback = []() {};
   rclcpp::CallbackGroup::SharedPtr cb_grp = node->create_callback_group(

rclcpp/test/rclcpp/test_executor.cpp

@@ -46,23 +46,6 @@ public:
   {
     spin_node_once_nanoseconds(node, std::chrono::milliseconds(100));
   }
-
-  rclcpp::memory_strategy::MemoryStrategy * memory_strategy_ptr()
-  {
-    return memory_strategy_.get();
-  }
-
-  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr local_get_node_by_group(
-    rclcpp::CallbackGroup::SharedPtr group)
-  {
-    std::lock_guard<std::mutex> guard_{mutex_};  // only to make the TSA happy
-    return get_node_by_group(weak_groups_to_nodes_, group);
-  }
-
-  rclcpp::CallbackGroup::SharedPtr local_get_group_by_timer(rclcpp::TimerBase::SharedPtr timer)
-  {
-    return get_group_by_timer(timer);
-  }
 };
 
 class TestExecutor : public ::testing::Test
@@ -130,7 +113,7 @@ TEST_F(TestExecutor, constructor_bad_wait_set_init) {
   auto mock = mocking_utils::patch_and_return("lib:rclcpp", rcl_wait_set_init, RCL_RET_ERROR);
   RCLCPP_EXPECT_THROW_EQ(
     static_cast<void>(std::make_unique<DummyExecutor>()),
-    std::runtime_error("Failed to create wait set in Executor constructor: error not set"));
+    std::runtime_error("Failed to create wait set: error not set"));
 }
 
 TEST_F(TestExecutor, add_callback_group_twice) {
@@ -142,7 +125,7 @@ TEST_F(TestExecutor, add_callback_group_twice) {
   cb_group->get_associated_with_executor_atomic().exchange(false);
   RCLCPP_EXPECT_THROW_EQ(
     dummy.add_callback_group(cb_group, node->get_node_base_interface(), false),
-    std::runtime_error("Callback group was already added to executor."));
+    std::runtime_error("Callback group has already been added to this executor."));
 }
 
 TEST_F(TestExecutor, add_callback_group_failed_trigger_guard_condition) {
@@ -168,9 +151,15 @@ TEST_F(TestExecutor, remove_callback_group_null_node) {
 
   node.reset();
 
+
+  /**
+   * TODO(mjcarroll): Assert this when we are enforcing that nodes must be destroyed
+   * after their created callback groups.
   RCLCPP_EXPECT_THROW_EQ(
     dummy.remove_callback_group(cb_group, false),
     std::runtime_error("Node must not be deleted before its callback group(s)."));
+   */
+  EXPECT_NO_THROW(dummy.remove_callback_group(cb_group, false));
 }
 
 TEST_F(TestExecutor, remove_callback_group_failed_trigger_guard_condition) {
@@ -197,7 +186,7 @@ TEST_F(TestExecutor, remove_node_not_associated) {
 
   RCLCPP_EXPECT_THROW_EQ(
     dummy.remove_node(node->get_node_base_interface(), false),
-    std::runtime_error("Node needs to be associated with an executor."));
+    std::runtime_error("Node '/ns/node' needs to be associated with an executor."));
 }
 
 TEST_F(TestExecutor, remove_node_associated_with_different_executor) {
@@ -211,7 +200,7 @@ TEST_F(TestExecutor, remove_node_associated_with_different_executor) {
 
   RCLCPP_EXPECT_THROW_EQ(
     dummy2.remove_node(node1->get_node_base_interface(), false),
-    std::runtime_error("Node needs to be associated with this executor."));
+    std::runtime_error("Node '/ns/node1' needs to be associated with this executor."));
 }
 
 TEST_F(TestExecutor, spin_node_once_nanoseconds) {
@@ -328,42 +317,14 @@ TEST_F(TestExecutor, cancel_failed_trigger_guard_condition) {
     std::runtime_error("Failed to trigger guard condition in cancel: error not set"));
 }
 
-TEST_F(TestExecutor, set_memory_strategy_nullptr) {
-  DummyExecutor dummy;
-
+TEST_F(TestExecutor, create_executor_fail_wait_set_clear) {
+  auto mock = mocking_utils::patch_and_return("lib:rclcpp", rcl_wait_set_clear, RCL_RET_ERROR);
   RCLCPP_EXPECT_THROW_EQ(
-    dummy.set_memory_strategy(nullptr),
-    std::runtime_error("Received NULL memory strategy in executor."));
+    DummyExecutor dummy,
+    std::runtime_error("Couldn't clear the wait set: error not set"));
 }
 
-TEST_F(TestExecutor, set_memory_strategy) {
-  DummyExecutor dummy;
-  rclcpp::memory_strategy::MemoryStrategy::SharedPtr strategy =
-    std::make_shared<
-    rclcpp::memory_strategies::allocator_memory_strategy::AllocatorMemoryStrategy<>>();
-
-  dummy.set_memory_strategy(strategy);
-  EXPECT_EQ(dummy.memory_strategy_ptr(), strategy.get());
-}
-
-TEST_F(TestExecutor, spin_once_failed_trigger_guard_condition) {
-  DummyExecutor dummy;
-  auto node = std::make_shared<rclcpp::Node>("node", "ns");
-  auto timer =
-    node->create_wall_timer(std::chrono::milliseconds(1), [&]() {});
-
-  dummy.add_node(node);
-  // Wait for the wall timer to have expired.
-  std::this_thread::sleep_for(std::chrono::milliseconds(50));
-  auto mock = mocking_utils::patch_and_return(
-    "lib:rclcpp", rcl_trigger_guard_condition, RCL_RET_ERROR);
-  RCLCPP_EXPECT_THROW_EQ(
-    dummy.spin_once(std::chrono::milliseconds(1)),
-    std::runtime_error(
-      "Failed to trigger guard condition from execute_any_executable: error not set"));
-}
-
-TEST_F(TestExecutor, spin_some_fail_wait_set_clear) {
+TEST_F(TestExecutor, spin_all_fail_wait_set_clear) {
   DummyExecutor dummy;
   auto node = std::make_shared<rclcpp::Node>("node", "ns");
   auto timer =
@@ -371,9 +332,10 @@ TEST_F(TestExecutor, spin_some_fail_wait_set_clear) {
 
   dummy.add_node(node);
   auto mock = mocking_utils::patch_and_return("lib:rclcpp", rcl_wait_set_clear, RCL_RET_ERROR);
+
   RCLCPP_EXPECT_THROW_EQ(
-    dummy.spin_some(std::chrono::milliseconds(1)),
-    std::runtime_error("Couldn't clear wait set: error not set"));
+    dummy.spin_all(std::chrono::milliseconds(1)),
+    std::runtime_error("Couldn't clear the wait set: error not set"));
 }
 
 TEST_F(TestExecutor, spin_some_fail_wait_set_resize) {
@@ -401,7 +363,7 @@ TEST_F(TestExecutor, spin_some_fail_add_handles_to_wait_set) {
     RCL_RET_ERROR);
   RCLCPP_EXPECT_THROW_EQ(
     dummy.spin_some(std::chrono::milliseconds(1)),
-    std::runtime_error("Couldn't fill wait set"));
+    std::runtime_error("Couldn't fill wait set: error not set"));
 }
 
 TEST_F(TestExecutor, spin_some_fail_wait) {
@@ -417,71 +379,6 @@ TEST_F(TestExecutor, spin_some_fail_wait) {
     std::runtime_error("rcl_wait() failed: error not set"));
 }
 
-TEST_F(TestExecutor, get_node_by_group_null_group) {
-  DummyExecutor dummy;
-  ASSERT_EQ(nullptr, dummy.local_get_node_by_group(nullptr));
-}
-
-TEST_F(TestExecutor, get_node_by_group) {
-  DummyExecutor dummy;
-  auto node = std::make_shared<rclcpp::Node>("node", "ns");
-  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
-    rclcpp::CallbackGroupType::MutuallyExclusive);
-  dummy.add_callback_group(cb_group, node->get_node_base_interface(), false);
-  ASSERT_EQ(node->get_node_base_interface().get(), dummy.local_get_node_by_group(cb_group).get());
-}
-
-TEST_F(TestExecutor, get_node_by_group_not_found) {
-  DummyExecutor dummy;
-  auto node = std::make_shared<rclcpp::Node>("node", "ns");
-  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
-    rclcpp::CallbackGroupType::MutuallyExclusive);
-  ASSERT_EQ(nullptr, dummy.local_get_node_by_group(cb_group).get());
-}
-
-TEST_F(TestExecutor, get_group_by_timer_nullptr) {
-  DummyExecutor dummy;
-  ASSERT_EQ(nullptr, dummy.local_get_group_by_timer(nullptr));
-}
-
-TEST_F(TestExecutor, get_group_by_timer) {
-  DummyExecutor dummy;
-  auto node = std::make_shared<rclcpp::Node>("node", "ns");
-  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
-    rclcpp::CallbackGroupType::MutuallyExclusive);
-  auto timer =
-    node->create_wall_timer(std::chrono::milliseconds(1), [&]() {}, cb_group);
-  dummy.add_node(node);
-
-  ASSERT_EQ(cb_group.get(), dummy.local_get_group_by_timer(timer).get());
-}
-
-TEST_F(TestExecutor, get_group_by_timer_with_deleted_group) {
-  DummyExecutor dummy;
-  auto node = std::make_shared<rclcpp::Node>("node", "ns");
-  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
-    rclcpp::CallbackGroupType::MutuallyExclusive);
-  auto timer =
-    node->create_wall_timer(std::chrono::milliseconds(1), [&]() {}, cb_group);
-  dummy.add_node(node);
-
-  cb_group.reset();
-
-  ASSERT_EQ(nullptr, dummy.local_get_group_by_timer(timer).get());
-}
-
-TEST_F(TestExecutor, get_group_by_timer_add_callback_group) {
-  DummyExecutor dummy;
-  auto node = std::make_shared<rclcpp::Node>("node", "ns");
-  rclcpp::CallbackGroup::SharedPtr cb_group = node->create_callback_group(
-    rclcpp::CallbackGroupType::MutuallyExclusive);
-  auto timer =
-    node->create_wall_timer(std::chrono::milliseconds(1), [&]() {}, cb_group);
-  dummy.add_callback_group(cb_group, node->get_node_base_interface(), false);
-
-  ASSERT_EQ(cb_group.get(), dummy.local_get_group_by_timer(timer).get());
-}
-
 TEST_F(TestExecutor, spin_until_future_complete_in_spin_until_future_complete) {
   DummyExecutor dummy;
   auto node = std::make_shared<rclcpp::Node>("node", "ns");

rclcpp/test/rclcpp/test_timers_manager.cpp

@@ -0,0 +1,419 @@
+// Copyright 2023 iRobot Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <gtest/gtest.h>
+
+#include <chrono>
+#include <memory>
+#include <utility>
+
+#include "rclcpp/contexts/default_context.hpp"
+#include "rclcpp/experimental/timers_manager.hpp"
+
+using namespace std::chrono_literals;
+
+using rclcpp::experimental::TimersManager;
+
+using CallbackT = std::function<void ()>;
+using TimerT = rclcpp::WallTimer<CallbackT>;
+
+class TestTimersManager : public ::testing::Test
+{
+public:
+  void SetUp()
+  {
+    rclcpp::init(0, nullptr);
+  }
+
+  void TearDown()
+  {
+    rclcpp::shutdown();
+  }
+};
+
+static void execute_all_ready_timers(std::shared_ptr<TimersManager> timers_manager)
+{
+  bool head_was_ready = false;
+  do {
+    head_was_ready = timers_manager->execute_head_timer();
+  } while (head_was_ready);
+}
+
+TEST_F(TestTimersManager, empty_manager)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  EXPECT_EQ(std::chrono::nanoseconds::max(), timers_manager->get_head_timeout());
+  EXPECT_FALSE(timers_manager->execute_head_timer());
+  EXPECT_NO_THROW(timers_manager->clear());
+  EXPECT_NO_THROW(timers_manager->start());
+  EXPECT_NO_THROW(timers_manager->stop());
+}
+
+TEST_F(TestTimersManager, add_run_remove_timer)
+{
+  size_t t_runs = 0;
+  auto t = TimerT::make_shared(
+    10ms,
+    [&t_runs]() {
+      t_runs++;
+    },
+    rclcpp::contexts::get_global_default_context());
+  std::weak_ptr<TimerT> t_weak = t;
+
+  // Add the timer to the timers manager
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+  timers_manager->add_timer(t);
+
+  // Sleep for more 3 times the timer period
+  std::this_thread::sleep_for(30ms);
+
+  // The timer is executed only once, even if we slept 3 times the period
+  execute_all_ready_timers(timers_manager);
+  EXPECT_EQ(1u, t_runs);
+
+  // Remove the timer from the manager
+  timers_manager->remove_timer(t);
+
+  t.reset();
+  // The timer is now not valid anymore
+  EXPECT_FALSE(t_weak.lock() != nullptr);
+}
+
+TEST_F(TestTimersManager, clear)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  auto t1 = TimerT::make_shared(1ms, CallbackT(), rclcpp::contexts::get_global_default_context());
+  std::weak_ptr<TimerT> t1_weak = t1;
+  auto t2 = TimerT::make_shared(1ms, CallbackT(), rclcpp::contexts::get_global_default_context());
+  std::weak_ptr<TimerT> t2_weak = t2;
+
+  timers_manager->add_timer(t1);
+  timers_manager->add_timer(t2);
+
+  EXPECT_TRUE(t1_weak.lock() != nullptr);
+  EXPECT_TRUE(t2_weak.lock() != nullptr);
+
+  timers_manager->clear();
+
+  t1.reset();
+  t2.reset();
+
+  EXPECT_FALSE(t1_weak.lock() != nullptr);
+  EXPECT_FALSE(t2_weak.lock() != nullptr);
+}
+
+TEST_F(TestTimersManager, remove_not_existing_timer)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  // Try to remove a nullptr timer
+  EXPECT_NO_THROW(timers_manager->remove_timer(nullptr));
+
+  auto t = TimerT::make_shared(1ms, CallbackT(), rclcpp::contexts::get_global_default_context());
+  timers_manager->add_timer(t);
+
+  // Remove twice the same timer
+  timers_manager->remove_timer(t);
+  EXPECT_NO_THROW(timers_manager->remove_timer(t));
+}
+
+TEST_F(TestTimersManager, timers_thread_exclusive_usage)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  timers_manager->start();
+
+  EXPECT_THROW(timers_manager->start(), std::exception);
+  EXPECT_THROW(timers_manager->get_head_timeout(), std::exception);
+  EXPECT_THROW(timers_manager->execute_head_timer(), std::exception);
+
+  timers_manager->stop();
+
+  EXPECT_NO_THROW(timers_manager->get_head_timeout());
+  EXPECT_NO_THROW(timers_manager->execute_head_timer());
+}
+
+TEST_F(TestTimersManager, add_timer_twice)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  auto t = TimerT::make_shared(1ms, CallbackT(), rclcpp::contexts::get_global_default_context());
+
+  timers_manager->add_timer(t);
+  EXPECT_NO_THROW(timers_manager->add_timer(t));
+}
+
+TEST_F(TestTimersManager, add_nullptr)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  EXPECT_THROW(timers_manager->add_timer(nullptr), std::exception);
+}
+
+TEST_F(TestTimersManager, head_not_ready)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  size_t t_runs = 0;
+  auto t = TimerT::make_shared(
+    10s,
+    [&t_runs]() {
+      t_runs++;
+    },
+    rclcpp::contexts::get_global_default_context());
+
+  timers_manager->add_timer(t);
+
+  // Timer will take 10s to get ready, so nothing to execute here
+  bool ret = timers_manager->execute_head_timer();
+  EXPECT_FALSE(ret);
+  EXPECT_EQ(0u, t_runs);
+}
+
+TEST_F(TestTimersManager, timers_order)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  size_t t1_runs = 0;
+  auto t1 = TimerT::make_shared(
+    10ms,
+    [&t1_runs]() {
+      t1_runs++;
+    },
+    rclcpp::contexts::get_global_default_context());
+
+  size_t t2_runs = 0;
+  auto t2 = TimerT::make_shared(
+    30ms,
+    [&t2_runs]() {
+      t2_runs++;
+    },
+    rclcpp::contexts::get_global_default_context());
+
+  size_t t3_runs = 0;
+  auto t3 = TimerT::make_shared(
+    100ms,
+    [&t3_runs]() {
+      t3_runs++;
+    },
+    rclcpp::contexts::get_global_default_context());
+
+  // Add timers in a random order
+  timers_manager->add_timer(t2);
+  timers_manager->add_timer(t3);
+  timers_manager->add_timer(t1);
+
+  std::this_thread::sleep_for(10ms);
+  execute_all_ready_timers(timers_manager);
+  EXPECT_EQ(1u, t1_runs);
+  EXPECT_EQ(0u, t2_runs);
+  EXPECT_EQ(0u, t3_runs);
+
+  std::this_thread::sleep_for(30ms);
+  execute_all_ready_timers(timers_manager);
+  EXPECT_EQ(2u, t1_runs);
+  EXPECT_EQ(1u, t2_runs);
+  EXPECT_EQ(0u, t3_runs);
+
+  std::this_thread::sleep_for(100ms);
+  execute_all_ready_timers(timers_manager);
+  EXPECT_EQ(3u, t1_runs);
+  EXPECT_EQ(2u, t2_runs);
+  EXPECT_EQ(1u, t3_runs);
+
+  timers_manager->remove_timer(t1);
+
+  std::this_thread::sleep_for(30ms);
+  execute_all_ready_timers(timers_manager);
+  EXPECT_EQ(3u, t1_runs);
+  EXPECT_EQ(3u, t2_runs);
+  EXPECT_EQ(1u, t3_runs);
+}
+
+TEST_F(TestTimersManager, start_stop_timers_thread)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  auto t = TimerT::make_shared(1ms, []() {}, rclcpp::contexts::get_global_default_context());
+  timers_manager->add_timer(t);
+
+  // Calling start multiple times will throw an error
+  EXPECT_NO_THROW(timers_manager->start());
+  EXPECT_THROW(timers_manager->start(), std::exception);
+
+  // Calling stop multiple times does not throw an error
+  EXPECT_NO_THROW(timers_manager->stop());
+  EXPECT_NO_THROW(timers_manager->stop());
+}
+
+TEST_F(TestTimersManager, timers_thread)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  size_t t1_runs = 0;
+  auto t1 = TimerT::make_shared(
+    1ms,
+    [&t1_runs]() {
+      t1_runs++;
+    },
+    rclcpp::contexts::get_global_default_context());
+
+  size_t t2_runs = 0;
+  auto t2 = TimerT::make_shared(
+    1ms,
+    [&t2_runs]() {
+      t2_runs++;
+    },
+    rclcpp::contexts::get_global_default_context());
+
+  // Add timers
+  timers_manager->add_timer(t1);
+  timers_manager->add_timer(t2);
+
+  // Run timers thread for a while
+  timers_manager->start();
+  std::this_thread::sleep_for(5ms);
+  timers_manager->stop();
+
+  EXPECT_LT(1u, t1_runs);
+  EXPECT_LT(1u, t2_runs);
+  EXPECT_EQ(t1_runs, t2_runs);
+}
+
+TEST_F(TestTimersManager, destructor)
+{
+  size_t t_runs = 0;
+  auto t = TimerT::make_shared(
+    1ms,
+    [&t_runs]() {
+      t_runs++;
+    },
+    rclcpp::contexts::get_global_default_context());
+  std::weak_ptr<TimerT> t_weak = t;
+
+  // When the timers manager is destroyed, it will stop the thread
+  // and clear the timers
+  {
+    auto timers_manager = std::make_shared<TimersManager>(
+      rclcpp::contexts::get_global_default_context());
+
+    timers_manager->add_timer(t);
+
+    timers_manager->start();
+    std::this_thread::sleep_for(100ms);
+
+    EXPECT_LT(1u, t_runs);
+  }
+
+  // The thread is not running anymore, so this value does not increase
+  size_t runs = t_runs;
+  std::this_thread::sleep_for(100ms);
+  EXPECT_EQ(runs, t_runs);
+  t.reset();
+  EXPECT_FALSE(t_weak.lock() != nullptr);
+}
+
+TEST_F(TestTimersManager, add_remove_while_thread_running)
+{
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  size_t t1_runs = 0;
+  auto t1 = TimerT::make_shared(
+    1ms,
+    [&t1_runs]() {
+      t1_runs++;
+    },
+    rclcpp::contexts::get_global_default_context());
+
+  size_t t2_runs = 0;
+  auto t2 = TimerT::make_shared(
+    1ms,
+    [&t2_runs]() {
+      t2_runs++;
+    },
+    rclcpp::contexts::get_global_default_context());
+
+  // Add timers
+  timers_manager->add_timer(t1);
+
+  // Start timers thread
+  timers_manager->start();
+
+  // After a while remove t1 and add t2
+  std::this_thread::sleep_for(5ms);
+  timers_manager->remove_timer(t1);
+  size_t tmp_t1 = t1_runs;
+  timers_manager->add_timer(t2);
+
+  // Wait some more time and then stop
+  std::this_thread::sleep_for(5ms);
+  timers_manager->stop();
+
+  // t1 has stopped running
+  EXPECT_EQ(tmp_t1, t1_runs);
+  // t2 is correctly running
+  EXPECT_LT(1u, t2_runs);
+}
+
+TEST_F(TestTimersManager, infinite_loop)
+{
+  // This test makes sure that even if timers have a period shorter than the duration
+  // of their callback the functions never block indefinitely.
+
+  auto timers_manager = std::make_shared<TimersManager>(
+    rclcpp::contexts::get_global_default_context());
+
+  size_t t1_runs = 0;
+  auto t1 = TimerT::make_shared(
+    1ms,
+    [&t1_runs]() {
+      t1_runs++;
+      std::this_thread::sleep_for(5ms);
+    },
+    rclcpp::contexts::get_global_default_context());
+
+  size_t t2_runs = 0;
+  auto t2 = TimerT::make_shared(
+    1ms,
+    [&t2_runs]() {
+      t2_runs++;
+      std::this_thread::sleep_for(5ms);
+    },
+    rclcpp::contexts::get_global_default_context());
+
+  timers_manager->add_timer(t1);
+  timers_manager->add_timer(t2);
+
+  // Start a timers thread and make sure that we can stop it later
+  timers_manager->start();
+  std::this_thread::sleep_for(50ms);
+  timers_manager->stop();
+
+  EXPECT_LT(0u, t1_runs);
+  EXPECT_LT(0u, t2_runs);
+}

rclcpp_action/CHANGELOG.rst

@@ -3,6 +3,13 @@ Changelog for package rclcpp_action
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 
+20.0.0 (2023-04-13)
+-------------------
+* extract the result response before the callback is issued. (`#2132 <https://github.com/ros2/rclcpp/issues/2132>`_)
+* Update all rclcpp packages to C++17. (`#2121 <https://github.com/ros2/rclcpp/issues/2121>`_)
+* Fix the GoalUUID to_string representation (`#1999 <https://github.com/ros2/rclcpp/issues/1999>`_)
+* Contributors: Chris Lalancette, Nathan Wiebe Neufeldt, Tomoya Fujita
+
 19.3.0 (2023-03-01)
 -------------------
 

rclcpp_action/package.xml

@@ -2,7 +2,7 @@
 <?xml-model href="http://download.ros.org/schema/package_format2.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
 <package format="2">
   <name>rclcpp_action</name>
-  <version>19.3.0</version>
+  <version>20.0.0</version>
   <description>Adds action APIs for C++.</description>
 
   <maintainer email="ivanpauno@ekumenlabs.com">Ivan Paunovic</maintainer>

rclcpp_components/CHANGELOG.rst

@@ -2,6 +2,11 @@
 Changelog for package rclcpp_components
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+20.0.0 (2023-04-13)
+-------------------
+* Update all rclcpp packages to C++17. (`#2121 <https://github.com/ros2/rclcpp/issues/2121>`_)
+* Contributors: Chris Lalancette
+
 19.3.0 (2023-03-01)
 -------------------
 

rclcpp_components/package.xml

@@ -2,7 +2,7 @@
 <?xml-model href="http://download.ros.org/schema/package_format2.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
 <package format="2">
   <name>rclcpp_components</name>
-  <version>19.3.0</version>
+  <version>20.0.0</version>
   <description>Package containing tools for dynamically loadable components</description>
 
   <maintainer email="ivanpauno@ekumenlabs.com">Ivan Paunovic</maintainer>

rclcpp_lifecycle/CHANGELOG.rst

@@ -3,6 +3,14 @@ Changelog for package rclcpp_lifecycle
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 
+20.0.0 (2023-04-13)
+-------------------
+* Fixes to silence some clang warnings. (`#2127 <https://github.com/ros2/rclcpp/issues/2127>`_)
+* Update all rclcpp packages to C++17. (`#2121 <https://github.com/ros2/rclcpp/issues/2121>`_)
+* Use the correct macro for LifecycleNode::get_fully_qualified_name (`#2117 <https://github.com/ros2/rclcpp/issues/2117>`_)
+* add get_fully_qualified_name to rclcpp_lifecycle (`#2115 <https://github.com/ros2/rclcpp/issues/2115>`_)
+* Contributors: Chris Lalancette, Steve Macenski
+
 19.3.0 (2023-03-01)
 -------------------
 

rclcpp_lifecycle/include/rclcpp_lifecycle/lifecycle_publisher.hpp

@@ -91,6 +91,24 @@ public:
     rclcpp::Publisher<MessageT, Alloc>::publish(msg);
   }
 
+  /// LifecyclePublisher publish function
+  /**
+   * The publish function checks whether the communication
+   * was enabled or disabled and forwards the message
+   * to the actual rclcpp Publisher base class
+   */
+  virtual void
+  publish(
+    rclcpp::LoanedMessage<typename rclcpp::Publisher<MessageT,
+    Alloc>::ROSMessageType, Alloc> && loaned_msg)
+  {
+    if (!this->is_activated()) {
+      log_publisher_not_enabled();
+      return;
+    }
+    rclcpp::Publisher<MessageT, Alloc>::publish(std::move(loaned_msg));
+  }
+
   void
   on_activate() override
   {

rclcpp_lifecycle/package.xml

@@ -2,7 +2,7 @@
 <?xml-model href="http://download.ros.org/schema/package_format2.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
 <package format="2">
   <name>rclcpp_lifecycle</name>
-  <version>19.3.0</version>
+  <version>20.0.0</version>
   <description>Package containing a prototype for lifecycle implementation</description>
 
   <maintainer email="ivanpauno@ekumenlabs.com">Ivan Paunovic</maintainer>

rclcpp_lifecycle/test/test_lifecycle_publisher.cpp

@@ -129,6 +129,10 @@ TEST_P(TestLifecyclePublisher, publish_managed_by_node) {
     auto msg_ptr = std::make_unique<test_msgs::msg::Empty>();
     EXPECT_NO_THROW(node_->publisher()->publish(std::move(msg_ptr)));
   }
+  {
+    auto loaned_msg = node_->publisher()->borrow_loaned_message();
+    EXPECT_NO_THROW(node_->publisher()->publish(std::move(loaned_msg)));
+  }
   node_->trigger_transition(
     rclcpp_lifecycle::Transition(Transition::TRANSITION_DEACTIVATE), ret);
   ASSERT_EQ(success, ret);
@@ -143,6 +147,10 @@ TEST_P(TestLifecyclePublisher, publish_managed_by_node) {
     auto msg_ptr = std::make_unique<test_msgs::msg::Empty>();
     EXPECT_NO_THROW(node_->publisher()->publish(std::move(msg_ptr)));
   }
+  {
+    auto loaned_msg = node_->publisher()->borrow_loaned_message();
+    EXPECT_NO_THROW(node_->publisher()->publish(std::move(loaned_msg)));
+  }
 }
 
 TEST_P(TestLifecyclePublisher, publish) {
@@ -157,6 +165,10 @@ TEST_P(TestLifecyclePublisher, publish) {
     auto msg_ptr = std::make_unique<test_msgs::msg::Empty>();
     EXPECT_NO_THROW(node_->publisher()->publish(std::move(msg_ptr)));
   }
+  {
+    auto loaned_msg = node_->publisher()->borrow_loaned_message();
+    EXPECT_NO_THROW(node_->publisher()->publish(std::move(loaned_msg)));
+  }
   node_->publisher()->on_activate();
   EXPECT_TRUE(node_->publisher()->is_activated());
   {
@@ -167,6 +179,10 @@ TEST_P(TestLifecyclePublisher, publish) {
     auto msg_ptr = std::make_unique<test_msgs::msg::Empty>();
     EXPECT_NO_THROW(node_->publisher()->publish(std::move(msg_ptr)));
   }
+  {
+    auto loaned_msg = node_->publisher()->borrow_loaned_message();
+    EXPECT_NO_THROW(node_->publisher()->publish(std::move(loaned_msg)));
+  }
 }
 
 INSTANTIATE_TEST_SUITE_P(