19.2.0

Signed-off-by: Chris Lalancette <clalancette@gmail.com>

.github/workflows/mirror-rolling-to-master.yaml

@@ -0,0 +1,13 @@
+name: Mirror rolling to master
+
+on:
+  push:
+    branches: [ rolling ]
+
+jobs:
+  mirror-to-master:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: zofrex/mirror-branch@v1
+      with:
+        target-branch: master

CODEOWNERS

@@ -0,0 +1,2 @@
+# This file was generated by https://github.com/audrow/update-ros2-repos
+* @ivanpauno @hidmic @wjwwood

README.md

@@ -8,7 +8,8 @@ rclcpp provides the standard C++ API for interacting with ROS 2.
 
 `#include "rclcpp/rclcpp.hpp"` allows use of the most common elements of the ROS 2 system.
 
-Visit the [rclcpp API documentation](http://docs.ros2.org/latest/api/rclcpp/) for a complete list of its main components.
+The link to the latest API documentation can be found on the rclcpp package info page, at the [ROS Index](https://index.ros.org/p/rclcpp/).
+
 
 ### Examples
 

rclcpp/CHANGELOG.rst

@@ -2,6 +2,99 @@
 Changelog for package rclcpp
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+19.2.0 (2023-02-24)
+-------------------
+* to create a sublogger while getting child of Logger (`#1717 <https://github.com/ros2/rclcpp/issues/1717>`_)
+* Fix documentation of Context class (`#2107 <https://github.com/ros2/rclcpp/issues/2107>`_)
+* fixes for rmw callbacks in qos_event class (`#2102 <https://github.com/ros2/rclcpp/issues/2102>`_)
+* Contributors: Alberto Soragna, Chen Lihui, Silvio Traversaro
+
+19.1.0 (2023-02-14)
+-------------------
+* Add support for timers on reset callback (`#1979 <https://github.com/ros2/rclcpp/issues/1979>`_)
+* Topic node guard condition in executor (`#2074 <https://github.com/ros2/rclcpp/issues/2074>`_)
+* Fix bug on the disorder of calling shutdown callback (`#2097 <https://github.com/ros2/rclcpp/issues/2097>`_)
+* Contributors: Barry Xu, Chen Lihui, mauropasse
+
+19.0.0 (2023-01-30)
+-------------------
+* Add default constructor to NodeInterfaces (`#2094 <https://github.com/ros2/rclcpp/issues/2094>`_)
+* Fix clock state cached time to be a copy, not a reference. (`#2092 <https://github.com/ros2/rclcpp/issues/2092>`_)
+* Fix -Wmaybe-uninitialized warning (`#2081 <https://github.com/ros2/rclcpp/issues/2081>`_)
+* Fix the keep_last warning when using system defaults. (`#2082 <https://github.com/ros2/rclcpp/issues/2082>`_)
+* Add in a fix for older compilers. (`#2075 <https://github.com/ros2/rclcpp/issues/2075>`_)
+* Contributors: Alexander Hans, Chris Lalancette, Shane Loretz
+
+18.0.0 (2022-12-29)
+-------------------
+* Implement Unified Node Interface (NodeInterfaces class) (`#2041 <https://github.com/ros2/rclcpp/issues/2041>`_)
+* Do not throw exception if trying to dequeue an empty intra-process buffer (`#2061 <https://github.com/ros2/rclcpp/issues/2061>`_)
+* Move event callback binding to PublisherBase and SubscriptionBase (`#2066 <https://github.com/ros2/rclcpp/issues/2066>`_)
+* Implement validity checks for rclcpp::Clock (`#2040 <https://github.com/ros2/rclcpp/issues/2040>`_)
+* Explicitly set callback type (`#2059 <https://github.com/ros2/rclcpp/issues/2059>`_)
+* Fix logging macros to build with msvc and cpp20 (`#2063 <https://github.com/ros2/rclcpp/issues/2063>`_)
+* Add clock type to node_options (`#1982 <https://github.com/ros2/rclcpp/issues/1982>`_)
+* Fix nullptr dereference in prune_requests_older_than (`#2008 <https://github.com/ros2/rclcpp/issues/2008>`_)
+* Remove templating on to_rcl_subscription_options (`#2056 <https://github.com/ros2/rclcpp/issues/2056>`_)
+* Fix SharedFuture from async_send_request never becoming valid (`#2044 <https://github.com/ros2/rclcpp/issues/2044>`_)
+* Add in a warning for a KeepLast depth of 0. (`#2048 <https://github.com/ros2/rclcpp/issues/2048>`_)
+* Mark rclcpp::Clock::now() as const (`#2050 <https://github.com/ros2/rclcpp/issues/2050>`_)
+* Fix a case that did not throw ParameterUninitializedException (`#2036 <https://github.com/ros2/rclcpp/issues/2036>`_)
+* Update maintainers (`#2043 <https://github.com/ros2/rclcpp/issues/2043>`_)
+* Contributors: Alberto Soragna, Audrow Nash, Chen Lihui, Chris Lalancette, Jeffery Hsu, Lei Liu, Mateusz Szczygielski, Shane Loretz, andrei, mauropasse, methylDragon
+
+17.1.0 (2022-11-02)
+-------------------
+* MultiThreadExecutor number of threads is at least 2+ in default. (`#2032 <https://github.com/ros2/rclcpp/issues/2032>`_)
+* Fix bug that a callback not reached (`#1640 <https://github.com/ros2/rclcpp/issues/1640>`_)
+* Set the minimum number of threads of the Multithreaded executor to 2 (`#2030 <https://github.com/ros2/rclcpp/issues/2030>`_)
+* check thread whether joinable before join (`#2019 <https://github.com/ros2/rclcpp/issues/2019>`_)
+* Set cpplint test timeout to 3 minutes (`#2022 <https://github.com/ros2/rclcpp/issues/2022>`_)
+* Make sure to include-what-you-use in the node_interfaces. (`#2018 <https://github.com/ros2/rclcpp/issues/2018>`_)
+* Do not clear entities callbacks on destruction (`#2002 <https://github.com/ros2/rclcpp/issues/2002>`_)
+* fix mismatched issue if using zero_allocate (`#1995 <https://github.com/ros2/rclcpp/issues/1995>`_)
+* Contributors: Alexis Paques, Chen Lihui, Chris Lalancette, Cristóbal Arroyo, Tomoya Fujita, mauropasse, uupks
+
+17.0.0 (2022-09-13)
+-------------------
+* Make ParameterService and Sync/AsyncParameterClient accept rclcpp::QoS (`#1978 <https://github.com/ros2/rclcpp/issues/1978>`_)
+* support regex match for parameter client (`#1992 <https://github.com/ros2/rclcpp/issues/1992>`_)
+* operator+= and operator-= for Duration (`#1988 <https://github.com/ros2/rclcpp/issues/1988>`_)
+* Revert "Revert "Add a create_timer method to Node and `LifecycleNode` classes (`#1975 <https://github.com/ros2/rclcpp/issues/1975>`_)" (`#2009 <https://github.com/ros2/rclcpp/issues/2009>`_) (`#2010 <https://github.com/ros2/rclcpp/issues/2010>`_)
+* force compiler warning if callback handles not captured (`#2000 <https://github.com/ros2/rclcpp/issues/2000>`_)
+* Revert "Add a `create_timer` method to `Node` and `LifecycleNode` classes (`#1975 <https://github.com/ros2/rclcpp/issues/1975>`_)" (`#2009 <https://github.com/ros2/rclcpp/issues/2009>`_)
+* Add a `create_timer` method to `Node` and `LifecycleNode` classes (`#1975 <https://github.com/ros2/rclcpp/issues/1975>`_)
+* [docs] add note about callback lifetime for {on, post}_set_parameter_callback (`#1981 <https://github.com/ros2/rclcpp/issues/1981>`_)
+* fix memory leak (`#1994 <https://github.com/ros2/rclcpp/issues/1994>`_)
+* Support pre-set and post-set parameter callbacks in addition to on-set-parameter-callback. (`#1947 <https://github.com/ros2/rclcpp/issues/1947>`_)
+* Make create_service accept rclcpp::QoS (`#1969 <https://github.com/ros2/rclcpp/issues/1969>`_)
+* Make create_client accept rclcpp::QoS (`#1964 <https://github.com/ros2/rclcpp/issues/1964>`_)
+* Fix the documentation for rclcpp::ok to be accurate. (`#1965 <https://github.com/ros2/rclcpp/issues/1965>`_)
+* use regex for wildcard matching (`#1839 <https://github.com/ros2/rclcpp/issues/1839>`_)
+* Revert "Introduce executors new spin_for method, replace spin_until_future_complete with spin_until_complete. (`#1821 <https://github.com/ros2/rclcpp/issues/1821>`_) (`#1874 <https://github.com/ros2/rclcpp/issues/1874>`_)" (`#1956 <https://github.com/ros2/rclcpp/issues/1956>`_)
+* Introduce executors new spin_for method, replace spin_until_future_complete with spin_until_complete. (`#1821 <https://github.com/ros2/rclcpp/issues/1821>`_) (`#1874 <https://github.com/ros2/rclcpp/issues/1874>`_)
+* test adjustment for LoanedMessage. (`#1951 <https://github.com/ros2/rclcpp/issues/1951>`_)
+* fix virtual dispatch issues identified by clang-tidy (`#1816 <https://github.com/ros2/rclcpp/issues/1816>`_)
+* Remove unused on_parameters_set_callback\_ (`#1945 <https://github.com/ros2/rclcpp/issues/1945>`_)
+* Fix subscription.is_serialized() for callbacks with message info (`#1950 <https://github.com/ros2/rclcpp/issues/1950>`_)
+* wait for subscriptions on another thread. (`#1940 <https://github.com/ros2/rclcpp/issues/1940>`_)
+* Fix documentation of `RCLCPP\_[INFO,WARN,...]` (`#1943 <https://github.com/ros2/rclcpp/issues/1943>`_)
+* Always trigger guard condition waitset (`#1923 <https://github.com/ros2/rclcpp/issues/1923>`_)
+* Add statistics for handle_loaned_message (`#1927 <https://github.com/ros2/rclcpp/issues/1927>`_)
+* Drop wrong template specialization (`#1926 <https://github.com/ros2/rclcpp/issues/1926>`_)
+* Contributors: Alberto Soragna, Andrew Symington, Barry Xu, Brian, Chen Lihui, Chris Lalancette, Daniel Reuter, Deepanshu Bansal, Hubert Liberacki, Ivan Santiago Paunovic, Jochen Sprickerhof, Nikolai Morin, Shane Loretz, Tomoya Fujita, Tyler Weaver, William Woodall, schrodinbug
+
+16.2.0 (2022-05-03)
+-------------------
+* Update get_parameter_from_event to follow the function description (`#1922 <https://github.com/ros2/rclcpp/issues/1922>`_)
+* Add 'best available' QoS enum values and methods (`#1920 <https://github.com/ros2/rclcpp/issues/1920>`_)
+* Contributors: Barry Xu, Jacob Perron
+
+16.1.0 (2022-04-29)
+-------------------
+* use reinterpret_cast for function pointer conversion. (`#1919 <https://github.com/ros2/rclcpp/issues/1919>`_)
+* Contributors: Tomoya Fujita
+
 16.0.1 (2022-04-13)
 -------------------
 * remove DEFINE_CONTENT_FILTER cmake option (`#1914 <https://github.com/ros2/rclcpp/issues/1914>`_)

rclcpp/CMakeLists.txt

@@ -259,4 +259,8 @@ if(TEST cppcheck)
   set_tests_properties(cppcheck PROPERTIES TIMEOUT 500)
 endif()
 
+if(TEST cpplint)
+  set_tests_properties(cpplint PROPERTIES TIMEOUT 180)
+endif()
+
 ament_generate_version_header(${PROJECT_NAME})

rclcpp/doc/proposed_node_parameter_callbacks.md

@@ -0,0 +1,29 @@
+# Proposed node parameters callback Design
+
+## Introduction:
+
+The original requirement came in **gazebo_ros_pkgs** for setting individual wheel slip parameters based on global wheel slip value [link to original issue](https://github.com/ros-simulation/gazebo_ros_pkgs/pull/1365). 
+
+The main requirement is to set one or more parameters after another parameter is set successfully. 
+
+Additionally, it would be nice if users could be notified locally (via a callback) when parameters have been set successfully (i.e. post validation).
+
+Related discussion can be found in [#609](https://github.com/ros2/rclcpp/issues/609) [#1789](https://github.com/ros2/rclcpp/pull/1789)
+
+With the current parameters API, the `add_on_set_parameters_callback` is intended for validation of parameter values before they are set, it should **not** cause any side-effects. 
+
+There is also the `ParameterEventHandler` that publishes changes to node parameters on `/parameter_events` topic for external nodes to see. Though the node could subscribe to the `/parameter_events` topic to be notified of changes to its own parameters, it is less than ideal since there is a delay caused by waiting for an executor to process the callback.
+
+We propose adding a `PostSetParametersCallbackHandle` for successful parameter set similar to `OnSetParametersCallbackHandle` for parameter validation. Also, we propose adding a `PreSetParametersCallbackHandle` useful for modifying list of parameters being set.
+
+The validation callback is often abused to trigger side effects in the code, for instance updating class attributes even before a parameter has been set successfully. Instead of relying on the `/parameter_events` topic to be notified of parameter changes, users can register a callback with a new API, `add_post_set_parameters_callback`.
+
+It is possible to use the proposed `add_post_set_parameters_callback` for setting additional parameters, but this might result in infinite recursion and does not allow those additional parameters to be set atomically with the original parameter(s) changed.
+To workaround these issues, we propose adding a "pre set" callback type that can be registered with `add_pre_set_parameters_callback`, which will be triggered before the validation callbacks and can be used to modify the parameter list. 
+
+![Desgin API](https://github.com/ros2/rclcpp/blob/deepanshu/local-param-changed-callback-support/rclcpp/doc/param_callback_design.png?raw=true)
+
+## Alternatives
+
+* Users could call `set_parameter` while processing a message from the `/parameter_events` topic, however, there is extra overhead in having to create subscription (as noted earlier).
+* Users could call `set_parameter` inside the "on set" parameters callback, however it is not well-defined how side-effects should handle cases where parameter validation fails.

rclcpp/include/rclcpp/allocator/allocator_common.hpp

@@ -15,6 +15,7 @@
 #ifndef RCLCPP__ALLOCATOR__ALLOCATOR_COMMON_HPP_
 #define RCLCPP__ALLOCATOR__ALLOCATOR_COMMON_HPP_
 
+#include <cstring>
 #include <memory>
 
 #include "rcl/allocator.h"
@@ -39,6 +40,22 @@ void * retyped_allocate(size_t size, void * untyped_allocator)
   return std::allocator_traits<Alloc>::allocate(*typed_allocator, size);
 }
 
+template<typename Alloc>
+void * retyped_zero_allocate(size_t number_of_elem, size_t size_of_elem, void * untyped_allocator)
+{
+  auto typed_allocator = static_cast<Alloc *>(untyped_allocator);
+  if (!typed_allocator) {
+    throw std::runtime_error("Received incorrect allocator type");
+  }
+  size_t size = number_of_elem * size_of_elem;
+  void * allocated_memory =
+    std::allocator_traits<Alloc>::allocate(*typed_allocator, size);
+  if (allocated_memory) {
+    std::memset(allocated_memory, 0, size);
+  }
+  return allocated_memory;
+}
+
 template<typename T, typename Alloc>
 void retyped_deallocate(void * untyped_pointer, void * untyped_allocator)
 {
@@ -73,6 +90,7 @@ rcl_allocator_t get_rcl_allocator(Alloc & allocator)
   rcl_allocator_t rcl_allocator = rcl_get_default_allocator();
 #ifndef _WIN32
   rcl_allocator.allocate = &retyped_allocate<Alloc>;
+  rcl_allocator.zero_allocate = &retyped_zero_allocate<Alloc>;
   rcl_allocator.deallocate = &retyped_deallocate<T, Alloc>;
   rcl_allocator.reallocate = &retyped_reallocate<T, Alloc>;
   rcl_allocator.state = &allocator;

rclcpp/include/rclcpp/any_subscription_callback.hpp

@@ -950,7 +950,13 @@ public:
       std::holds_alternative<UniquePtrSerializedMessageCallback>(callback_variant_) ||
       std::holds_alternative<SharedConstPtrSerializedMessageCallback>(callback_variant_) ||
       std::holds_alternative<ConstRefSharedConstPtrSerializedMessageCallback>(callback_variant_) ||
-      std::holds_alternative<SharedPtrSerializedMessageCallback>(callback_variant_);
+      std::holds_alternative<SharedPtrSerializedMessageCallback>(callback_variant_) ||
+      std::holds_alternative<ConstRefSerializedMessageWithInfoCallback>(callback_variant_) ||
+      std::holds_alternative<UniquePtrSerializedMessageWithInfoCallback>(callback_variant_) ||
+      std::holds_alternative<SharedConstPtrSerializedMessageWithInfoCallback>(callback_variant_) ||
+      std::holds_alternative<ConstRefSharedConstPtrSerializedMessageWithInfoCallback>(
+      callback_variant_) ||
+      std::holds_alternative<SharedPtrSerializedMessageWithInfoCallback>(callback_variant_);
   }
 
   void

rclcpp/include/rclcpp/callback_group.hpp

@@ -16,11 +16,14 @@
 #define RCLCPP__CALLBACK_GROUP_HPP_
 
 #include <atomic>
+#include <functional>
+#include <memory>
 #include <mutex>
-#include <string>
 #include <vector>
 
 #include "rclcpp/client.hpp"
+#include "rclcpp/context.hpp"
+#include "rclcpp/guard_condition.hpp"
 #include "rclcpp/publisher_base.hpp"
 #include "rclcpp/service.hpp"
 #include "rclcpp/subscription_base.hpp"
@@ -95,6 +98,10 @@ public:
     CallbackGroupType group_type,
     bool automatically_add_to_executor_with_node = true);
 
+  /// Default destructor.
+  RCLCPP_PUBLIC
+  ~CallbackGroup();
+
   template<typename Function>
   rclcpp::SubscriptionBase::SharedPtr
   find_subscription_ptrs_if(Function func) const
@@ -171,6 +178,16 @@ public:
   bool
   automatically_add_to_executor_with_node() const;
 
+  /// Defer creating the notify guard condition and return it.
+  RCLCPP_PUBLIC
+  rclcpp::GuardCondition::SharedPtr
+  get_notify_guard_condition(const rclcpp::Context::SharedPtr context_ptr);
+
+  /// Trigger the notify guard condition.
+  RCLCPP_PUBLIC
+  void
+  trigger_notify_guard_condition();
+
 protected:
   RCLCPP_DISABLE_COPY(CallbackGroup)
 
@@ -213,6 +230,9 @@ protected:
   std::vector<rclcpp::Waitable::WeakPtr> waitable_ptrs_;
   std::atomic_bool can_be_taken_from_;
   const bool automatically_add_to_executor_with_node_;
+  // defer the creation of the guard condition
+  std::shared_ptr<rclcpp::GuardCondition> notify_guard_condition_ = nullptr;
+  std::recursive_mutex notify_guard_condition_mutex_;
 
 private:
   template<typename TypeT, typename Function>

rclcpp/include/rclcpp/client.hpp

@@ -130,7 +130,7 @@ public:
     rclcpp::node_interfaces::NodeGraphInterface::SharedPtr node_graph);
 
   RCLCPP_PUBLIC
-  virtual ~ClientBase();
+  virtual ~ClientBase() = default;
 
   /// Take the next response for this client as a type erased pointer.
   /**
@@ -312,7 +312,7 @@ public:
     // This two-step setting, prevents a gap where the old std::function has
     // been replaced but the middleware hasn't been told about the new one yet.
     set_on_new_response_callback(
-      rclcpp::detail::cpp_callback_trampoline<const void *, size_t>,
+      rclcpp::detail::cpp_callback_trampoline<decltype(new_callback), const void *, size_t>,
       static_cast<const void *>(&new_callback));
 
     // Store the std::function to keep it in scope, also overwrites the existing one.
@@ -320,7 +320,8 @@ public:
 
     // Set it again, now using the permanent storage.
     set_on_new_response_callback(
-      rclcpp::detail::cpp_callback_trampoline<const void *, size_t>,
+      rclcpp::detail::cpp_callback_trampoline<
+        decltype(on_new_response_callback_), const void *, size_t>,
       static_cast<const void *>(&on_new_response_callback_));
   }
 
@@ -769,7 +770,9 @@ public:
     auto old_size = pending_requests_.size();
     for (auto it = pending_requests_.begin(), last = pending_requests_.end(); it != last; ) {
       if (it->second.first < time_point) {
-        pruned_requests->push_back(it->first);
+        if (pruned_requests) {
+          pruned_requests->push_back(it->first);
+        }
         it = pending_requests_.erase(it);
       } else {
         ++it;
@@ -792,16 +795,14 @@ protected:
   async_send_request_impl(const Request & request, CallbackInfoVariant value)
   {
     int64_t sequence_number;
+    std::lock_guard<std::mutex> lock(pending_requests_mutex_);
     rcl_ret_t ret = rcl_send_request(get_client_handle().get(), &request, &sequence_number);
     if (RCL_RET_OK != ret) {
       rclcpp::exceptions::throw_from_rcl_error(ret, "failed to send request");
     }
-    {
-      std::lock_guard<std::mutex> lock(pending_requests_mutex_);
-      pending_requests_.try_emplace(
-        sequence_number,
-        std::make_pair(std::chrono::system_clock::now(), std::move(value)));
-    }
+    pending_requests_.try_emplace(
+      sequence_number,
+      std::make_pair(std::chrono::system_clock::now(), std::move(value)));
     return sequence_number;
   }
 

rclcpp/include/rclcpp/clock.hpp

@@ -77,7 +77,7 @@ public:
    */
   RCLCPP_PUBLIC
   Time
-  now();
+  now() const;
 
   /**
    * Sleep until a specified Time, according to clock type.
@@ -137,6 +137,51 @@ public:
     Duration rel_time,
     Context::SharedPtr context = contexts::get_global_default_context());
 
+  /**
+   * Check if the clock is started.
+   *
+   * A started clock is a clock that reflects non-zero time.
+   * Typically a clock will be unstarted if it is using RCL_ROS_TIME with ROS time and
+   * nothing has been published on the clock topic yet.
+   *
+   * \return true if clock is started
+   * \throws std::runtime_error if the clock is not rcl_clock_valid
+   */
+  RCLCPP_PUBLIC
+  bool
+  started();
+
+  /**
+   * Wait until clock to start.
+   *
+   * \rclcpp::Clock::started
+   * \param context the context to wait in
+   * \return true if clock was already started or became started
+   * \throws std::runtime_error if the context is invalid or clock is not rcl_clock_valid
+   */
+  RCLCPP_PUBLIC
+  bool
+  wait_until_started(Context::SharedPtr context = contexts::get_global_default_context());
+
+  /**
+   * Wait for clock to start, with timeout.
+   *
+   * The timeout is waited in steady time.
+   *
+   * \rclcpp::Clock::started
+   * \param timeout the maximum time to wait for.
+   * \param context the context to wait in.
+   * \param wait_tick_ns the time to wait between each iteration of the wait loop (in nanoseconds).
+   * \return true if clock was or became valid
+   * \throws std::runtime_error if the context is invalid or clock is not rcl_clock_valid
+   */
+  RCLCPP_PUBLIC
+  bool
+  wait_until_started(
+    const rclcpp::Duration & timeout,
+    Context::SharedPtr context = contexts::get_global_default_context(),
+    const rclcpp::Duration & wait_tick_ns = rclcpp::Duration(0, static_cast<uint32_t>(1e7)));
+
   /**
    * Returns the clock of the type `RCL_ROS_TIME` is active.
    *

rclcpp/include/rclcpp/context.hpp

@@ -65,8 +65,11 @@ using PreShutdownCallbackHandle = ShutdownCallbackHandle;
 /// Context which encapsulates shared state between nodes and other similar entities.
 /**
  * A context also represents the lifecycle between init and shutdown of rclcpp.
- * It is often used in conjunction with rclcpp::init, or rclcpp::init_local,
- * and rclcpp::shutdown.
+ * Nodes may be attached to a particular context by passing to the rclcpp::Node
+ * constructor a rclcpp::NodeOptions instance in which the Context is set via
+ * rclcpp::NodeOptions::context.
+ * Nodes will be automatically removed from the context when destructed.
+ * Contexts may be shutdown by calling rclcpp::shutdown.
  */
 class Context : public std::enable_shared_from_this<Context>
 {
@@ -183,6 +186,11 @@ public:
    *
    * This function is thread-safe.
    *
+   * Note that if you override this method, but leave shutdown to be called in
+   * the destruction of this base class, it will not call the overridden
+   * version from your base class.
+   * So you need to ensure you call your class's shutdown() in its destructor.
+   *
    * \param[in] reason the description of why shutdown happened
    * \return true if shutdown was successful, false if context was already shutdown
    * \throw various exceptions derived from rclcpp::exceptions::RCLError, if rcl_shutdown fails
@@ -318,7 +326,6 @@ public:
 
   /// Interrupt any blocking sleep_for calls, causing them to return immediately and return true.
   RCLCPP_PUBLIC
-  virtual
   void
   interrupt_all_sleep_for();
 
@@ -351,7 +358,6 @@ protected:
   // Called by constructor and destructor to clean up by finalizing the
   // shutdown rcl context and preparing for a new init cycle.
   RCLCPP_PUBLIC
-  virtual
   void
   clean_up();
 
@@ -373,10 +379,10 @@ private:
   // attempt to acquire another sub context.
   std::recursive_mutex sub_contexts_mutex_;
 
-  std::unordered_set<std::shared_ptr<OnShutdownCallback>> on_shutdown_callbacks_;
+  std::vector<std::shared_ptr<OnShutdownCallback>> on_shutdown_callbacks_;
   mutable std::mutex on_shutdown_callbacks_mutex_;
 
-  std::unordered_set<std::shared_ptr<PreShutdownCallback>> pre_shutdown_callbacks_;
+  std::vector<std::shared_ptr<PreShutdownCallback>> pre_shutdown_callbacks_;
   mutable std::mutex pre_shutdown_callbacks_mutex_;
 
   /// Condition variable for timed sleep (see sleep_for).
@@ -395,20 +401,22 @@ private:
 
   using ShutdownCallback = ShutdownCallbackHandle::ShutdownCallbackType;
 
+  template<ShutdownType shutdown_type>
   RCLCPP_LOCAL
   ShutdownCallbackHandle
   add_shutdown_callback(
-    ShutdownType shutdown_type,
     ShutdownCallback callback);
 
+  template<ShutdownType shutdown_type>
   RCLCPP_LOCAL
   bool
   remove_shutdown_callback(
-    ShutdownType shutdown_type,
     const ShutdownCallbackHandle & callback_handle);
 
+  template<ShutdownType shutdown_type>
+  RCLCPP_LOCAL
   std::vector<rclcpp::Context::ShutdownCallback>
-  get_shutdown_callback(ShutdownType shutdown_type) const;
+  get_shutdown_callback() const;
 };
 
 /// Return a copy of the list of context shared pointers.

rclcpp/include/rclcpp/create_client.hpp

@@ -20,10 +20,40 @@
 
 #include "rclcpp/node_interfaces/node_base_interface.hpp"
 #include "rclcpp/node_interfaces/node_services_interface.hpp"
+#include "rclcpp/qos.hpp"
 #include "rmw/rmw.h"
 
 namespace rclcpp
 {
+/// Create a service client with a given type.
+/**
+ * \param[in] node_base NodeBaseInterface implementation of the node on which
+ *  to create the client.
+ * \param[in] node_graph NodeGraphInterface implementation of the node on which
+ *  to create the client.
+ * \param[in] node_services NodeServicesInterface implementation of the node on
+ *  which to create the client.
+ * \param[in] service_name The name on which the service is accessible.
+ * \param[in] qos Quality of service profile for client.
+ * \param[in] group Callback group to handle the reply to service calls.
+ * \return Shared pointer to the created client.
+ */
+template<typename ServiceT>
+typename rclcpp::Client<ServiceT>::SharedPtr
+create_client(
+  std::shared_ptr<node_interfaces::NodeBaseInterface> node_base,
+  std::shared_ptr<node_interfaces::NodeGraphInterface> node_graph,
+  std::shared_ptr<node_interfaces::NodeServicesInterface> node_services,
+  const std::string & service_name,
+  const rclcpp::QoS & qos = rclcpp::ServicesQoS(),
+  rclcpp::CallbackGroup::SharedPtr group = nullptr)
+{
+  return create_client<ServiceT>(
+    node_base, node_graph, node_services,
+    service_name,
+    qos.get_rmw_qos_profile(),
+    group);
+}
 
 /// Create a service client with a given type.
 /// \internal

rclcpp/include/rclcpp/create_service.hpp

@@ -26,6 +26,32 @@
 
 namespace rclcpp
 {
+/// Create a service with a given type.
+/**
+ * \param[in] node_base NodeBaseInterface implementation of the node on which
+ *  to create the service.
+ * \param[in] node_services NodeServicesInterface implementation of the node on
+ *  which to create the service.
+ * \param[in] service_name The name on which the service is accessible.
+ * \param[in] callback The callback to call when the service gets a request.
+ * \param[in] qos Quality of service profile for the service.
+ * \param[in] group Callback group to handle the reply to service calls.
+ * \return Shared pointer to the created service.
+ */
+template<typename ServiceT, typename CallbackT>
+typename rclcpp::Service<ServiceT>::SharedPtr
+create_service(
+  std::shared_ptr<node_interfaces::NodeBaseInterface> node_base,
+  std::shared_ptr<node_interfaces::NodeServicesInterface> node_services,
+  const std::string & service_name,
+  CallbackT && callback,
+  const rclcpp::QoS & qos,
+  rclcpp::CallbackGroup::SharedPtr group)
+{
+  return create_service<ServiceT, CallbackT>(
+    node_base, node_services, service_name,
+    std::forward<CallbackT>(callback), qos.get_rmw_qos_profile(), group);
+}
 
 /// Create a service with a given type.
 /// \internal

rclcpp/include/rclcpp/create_timer.hpp

@@ -23,85 +23,29 @@
 
 #include "rclcpp/duration.hpp"
 #include "rclcpp/node_interfaces/get_node_base_interface.hpp"
+#include "rclcpp/node_interfaces/get_node_clock_interface.hpp"
 #include "rclcpp/node_interfaces/get_node_timers_interface.hpp"
 #include "rclcpp/node_interfaces/node_base_interface.hpp"
+#include "rclcpp/node_interfaces/node_clock_interface.hpp"
 #include "rclcpp/node_interfaces/node_timers_interface.hpp"
 
 namespace rclcpp
 {
-/// Create a timer with a given clock
-/// \internal
-template<typename CallbackT>
-typename rclcpp::TimerBase::SharedPtr
-create_timer(
-  std::shared_ptr<node_interfaces::NodeBaseInterface> node_base,
-  std::shared_ptr<node_interfaces::NodeTimersInterface> node_timers,
-  rclcpp::Clock::SharedPtr clock,
-  rclcpp::Duration period,
-  CallbackT && callback,
-  rclcpp::CallbackGroup::SharedPtr group = nullptr)
+namespace detail
 {
-  auto timer = rclcpp::GenericTimer<CallbackT>::make_shared(
-    clock,
-    period.to_chrono<std::chrono::nanoseconds>(),
-    std::forward<CallbackT>(callback),
-    node_base->get_context());
-
-  node_timers->add_timer(timer, group);
-  return timer;
-}
-
-/// Create a timer with a given clock
-template<typename NodeT, typename CallbackT>
-typename rclcpp::TimerBase::SharedPtr
-create_timer(
-  NodeT node,
-  rclcpp::Clock::SharedPtr clock,
-  rclcpp::Duration period,
-  CallbackT && callback,
-  rclcpp::CallbackGroup::SharedPtr group = nullptr)
-{
-  return create_timer(
-    rclcpp::node_interfaces::get_node_base_interface(node),
-    rclcpp::node_interfaces::get_node_timers_interface(node),
-    clock,
-    period,
-    std::forward<CallbackT>(callback),
-    group);
-}
-
-/// Convenience method to create a timer with node resources.
+/// Perform a safe cast to a timer period in nanoseconds
 /**
  *
  * \tparam DurationRepT
  * \tparam DurationT
- * \tparam CallbackT
  * \param period period to execute callback. This duration must be 0 <= period < nanoseconds::max()
- * \param callback callback to execute via the timer period
- * \param group
- * \param node_base
- * \param node_timers
- * \return
- * \throws std::invalid argument if either node_base or node_timers
- * are null, or period is negative or too large
+ * \return period, expressed as chrono::duration::nanoseconds
+ * \throws std::invalid_argument if period is negative or too large
  */
-template<typename DurationRepT, typename DurationT, typename CallbackT>
-typename rclcpp::WallTimer<CallbackT>::SharedPtr
-create_wall_timer(
-  std::chrono::duration<DurationRepT, DurationT> period,
-  CallbackT callback,
-  rclcpp::CallbackGroup::SharedPtr group,
-  node_interfaces::NodeBaseInterface * node_base,
-  node_interfaces::NodeTimersInterface * node_timers)
+template<typename DurationRepT, typename DurationT>
+std::chrono::nanoseconds
+safe_cast_to_period_in_ns(std::chrono::duration<DurationRepT, DurationT> period)
 {
-  if (node_base == nullptr) {
-    throw std::invalid_argument{"input node_base cannot be null"};
-  }
-
-  if (node_timers == nullptr) {
-    throw std::invalid_argument{"input node_timers cannot be null"};
-  }
-
   if (period < std::chrono::duration<DurationRepT, DurationT>::zero()) {
     throw std::invalid_argument{"timer period cannot be negative"};
   }
@@ -132,12 +76,135 @@ create_wall_timer(
             "Casting timer period to nanoseconds resulted in integer overflow."};
   }
 
+  return period_ns;
+}
+}  // namespace detail
+
+/// Create a timer with a given clock
+/// \internal
+template<typename CallbackT>
+typename rclcpp::TimerBase::SharedPtr
+create_timer(
+  std::shared_ptr<node_interfaces::NodeBaseInterface> node_base,
+  std::shared_ptr<node_interfaces::NodeTimersInterface> node_timers,
+  rclcpp::Clock::SharedPtr clock,
+  rclcpp::Duration period,
+  CallbackT && callback,
+  rclcpp::CallbackGroup::SharedPtr group = nullptr)
+{
+  return create_timer(
+    clock,
+    period.to_chrono<std::chrono::nanoseconds>(),
+    std::forward<CallbackT>(callback),
+    group,
+    node_base.get(),
+    node_timers.get());
+}
+
+/// Create a timer with a given clock
+template<typename NodeT, typename CallbackT>
+typename rclcpp::TimerBase::SharedPtr
+create_timer(
+  NodeT node,
+  rclcpp::Clock::SharedPtr clock,
+  rclcpp::Duration period,
+  CallbackT && callback,
+  rclcpp::CallbackGroup::SharedPtr group = nullptr)
+{
+  return create_timer(
+    clock,
+    period.to_chrono<std::chrono::nanoseconds>(),
+    std::forward<CallbackT>(callback),
+    group,
+    rclcpp::node_interfaces::get_node_base_interface(node).get(),
+    rclcpp::node_interfaces::get_node_timers_interface(node).get());
+}
+
+/// Convenience method to create a general timer with node resources.
+/**
+ *
+ * \tparam DurationRepT
+ * \tparam DurationT
+ * \tparam CallbackT
+ * \param clock clock to be used
+ * \param period period to execute callback. This duration must be 0 <= period < nanoseconds::max()
+ * \param callback callback to execute via the timer period
+ * \param group callback group
+ * \param node_base node base interface
+ * \param node_timers node timer interface
+ * \return shared pointer to a generic timer
+ * \throws std::invalid_argument if either clock, node_base or node_timers
+ * are nullptr, or period is negative or too large
+ */
+template<typename DurationRepT, typename DurationT, typename CallbackT>
+typename rclcpp::GenericTimer<CallbackT>::SharedPtr
+create_timer(
+  rclcpp::Clock::SharedPtr clock,
+  std::chrono::duration<DurationRepT, DurationT> period,
+  CallbackT callback,
+  rclcpp::CallbackGroup::SharedPtr group,
+  node_interfaces::NodeBaseInterface * node_base,
+  node_interfaces::NodeTimersInterface * node_timers)
+{
+  if (clock == nullptr) {
+    throw std::invalid_argument{"clock cannot be null"};
+  }
+  if (node_base == nullptr) {
+    throw std::invalid_argument{"input node_base cannot be null"};
+  }
+  if (node_timers == nullptr) {
+    throw std::invalid_argument{"input node_timers cannot be null"};
+  }
+
+  const std::chrono::nanoseconds period_ns = detail::safe_cast_to_period_in_ns(period);
+
+  // Add a new generic timer.
+  auto timer = rclcpp::GenericTimer<CallbackT>::make_shared(
+    std::move(clock), period_ns, std::move(callback), node_base->get_context());
+  node_timers->add_timer(timer, group);
+  return timer;
+}
+
+/// Convenience method to create a wall timer with node resources.
+/**
+ *
+ * \tparam DurationRepT
+ * \tparam DurationT
+ * \tparam CallbackT
+ * \param period period to execute callback. This duration must be 0 <= period < nanoseconds::max()
+ * \param callback callback to execute via the timer period
+ * \param group callback group
+ * \param node_base node base interface
+ * \param node_timers node timer interface
+ * \return shared pointer to a wall timer
+ * \throws std::invalid_argument if either node_base or node_timers
+ * are null, or period is negative or too large
+ */
+template<typename DurationRepT, typename DurationT, typename CallbackT>
+typename rclcpp::WallTimer<CallbackT>::SharedPtr
+create_wall_timer(
+  std::chrono::duration<DurationRepT, DurationT> period,
+  CallbackT callback,
+  rclcpp::CallbackGroup::SharedPtr group,
+  node_interfaces::NodeBaseInterface * node_base,
+  node_interfaces::NodeTimersInterface * node_timers)
+{
+  if (node_base == nullptr) {
+    throw std::invalid_argument{"input node_base cannot be null"};
+  }
+
+  if (node_timers == nullptr) {
+    throw std::invalid_argument{"input node_timers cannot be null"};
+  }
+
+  const std::chrono::nanoseconds period_ns = detail::safe_cast_to_period_in_ns(period);
+
+  // Add a new wall timer.
   auto timer = rclcpp::WallTimer<CallbackT>::make_shared(
     period_ns, std::move(callback), node_base->get_context());
   node_timers->add_timer(timer, group);
   return timer;
 }
-
 }  // namespace rclcpp
 
 #endif  // RCLCPP__CREATE_TIMER_HPP_

rclcpp/include/rclcpp/detail/cpp_callback_trampoline.hpp

@@ -41,6 +41,7 @@ namespace detail
  * so no exceptions should be thrown at this point, and doing so results in
  * undefined behavior.
  *
+ * \tparam UserDataRealT Declared type of the passed function
  * \tparam UserDataT Deduced type based on what is passed for user data,
  *   usually this type is either `void *` or `const void *`.
  * \tparam Args the arguments being passed to the callback
@@ -50,6 +51,7 @@ namespace detail
  * \returns whatever the callback returns, if anything
  */
 template<
+  typename UserDataRealT,
   typename UserDataT,
   typename ... Args,
   typename ReturnT = void
@@ -57,7 +59,7 @@ template<
 ReturnT
 cpp_callback_trampoline(UserDataT user_data, Args ... args) noexcept
 {
-  auto & actual_callback = *reinterpret_cast<const std::function<ReturnT(Args...)> *>(user_data);
+  auto & actual_callback = *static_cast<const UserDataRealT *>(user_data);
   return actual_callback(args ...);
 }
 

rclcpp/include/rclcpp/detail/template_contains.hpp

@@ -0,0 +1,47 @@
+// Copyright 2022 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__DETAIL__TEMPLATE_CONTAINS_HPP_
+#define RCLCPP__DETAIL__TEMPLATE_CONTAINS_HPP_
+
+#include <type_traits>
+
+namespace rclcpp
+{
+namespace detail
+{
+
+/// Template meta-function that checks if a given T is contained in the list Us.
+template<typename T, typename ... Us>
+struct template_contains;
+
+template<typename ... Args>
+inline constexpr bool template_contains_v = template_contains<Args ...>::value;
+
+template<typename T, typename NextT, typename ... Us>
+struct template_contains<T, NextT, Us ...>
+{
+  enum { value = (std::is_same_v<T, NextT>|| template_contains_v<T, Us ...>)};
+};
+
+template<typename T>
+struct template_contains<T>
+{
+  enum { value = false };
+};
+
+}  // namespace detail
+}  // namespace rclcpp
+
+#endif  // RCLCPP__DETAIL__TEMPLATE_CONTAINS_HPP_

rclcpp/include/rclcpp/detail/template_unique.hpp

@@ -0,0 +1,49 @@
+// Copyright 2022 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__DETAIL__TEMPLATE_UNIQUE_HPP_
+#define RCLCPP__DETAIL__TEMPLATE_UNIQUE_HPP_
+
+#include <type_traits>
+
+#include "rclcpp/detail/template_contains.hpp"
+
+namespace rclcpp
+{
+namespace detail
+{
+
+/// Template meta-function that checks if a given list Ts contains unique types.
+template<typename ... Ts>
+struct template_unique;
+
+template<typename ... Args>
+inline constexpr bool template_unique_v = template_unique<Args ...>::value;
+
+template<typename NextT, typename ... Ts>
+struct template_unique<NextT, Ts ...>
+{
+  enum { value = !template_contains_v<NextT, Ts ...>&& template_unique_v<Ts ...>};
+};
+
+template<typename T>
+struct template_unique<T>
+{
+  enum { value = true };
+};
+
+}  // namespace detail
+}  // namespace rclcpp
+
+#endif  // RCLCPP__DETAIL__TEMPLATE_UNIQUE_HPP_

rclcpp/include/rclcpp/duration.hpp

@@ -92,9 +92,13 @@ public:
   Duration
   operator+(const rclcpp::Duration & rhs) const;
 
+  Duration & operator+=(const rclcpp::Duration & rhs);
+
   Duration
   operator-(const rclcpp::Duration & rhs) const;
 
+  Duration & operator-=(const rclcpp::Duration & rhs);
+
   /// Get the maximum representable value.
   /**
    * \return the maximum representable value
@@ -106,6 +110,9 @@ public:
   Duration
   operator*(double scale) const;
 
+  Duration &
+  operator*=(double scale);
+
   /// Get duration in nanosecods
   /**
    * \return the duration in nanoseconds as a rcl_duration_value_t.

rclcpp/include/rclcpp/executor.hpp

@@ -565,10 +565,19 @@ protected:
       std::owner_less<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr>>
     WeakNodesToGuardConditionsMap;
 
+  typedef std::map<rclcpp::CallbackGroup::WeakPtr,
+      const rclcpp::GuardCondition *,
+      std::owner_less<rclcpp::CallbackGroup::WeakPtr>>
+    WeakCallbackGroupsToGuardConditionsMap;
+
   /// maps nodes to guard conditions
   WeakNodesToGuardConditionsMap
   weak_nodes_to_guard_conditions_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
 
+  /// maps callback groups to guard conditions
+  WeakCallbackGroupsToGuardConditionsMap
+  weak_groups_to_guard_conditions_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
+
   /// maps callback groups associated to nodes
   WeakCallbackGroupsToNodesMap
   weak_groups_associated_with_executor_to_nodes_ RCPPUTILS_TSA_GUARDED_BY(mutex_);

rclcpp/include/rclcpp/executors/multi_threaded_executor.hpp

@@ -47,7 +47,7 @@ public:
    *
    * \param options common options for all executors
    * \param number_of_threads number of threads to have in the thread pool,
-   *   the default 0 will use the number of cpu cores found instead
+   *   the default 0 will use the number of cpu cores found (minimum of 2)
    * \param yield_before_execute if true std::this_thread::yield() is called
    * \param timeout maximum time to wait
    */

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

@@ -86,8 +86,7 @@ public:
     std::lock_guard<std::mutex> lock(mutex_);
 
     if (!has_data_()) {
-      RCLCPP_ERROR(rclcpp::get_logger("rclcpp"), "Calling dequeue on empty intra-process buffer");
-      throw std::runtime_error("Calling dequeue on empty intra-process buffer");
+      return BufferT();
     }
 
     auto request = std::move(ring_buffer_[read_index_]);

rclcpp/include/rclcpp/experimental/subscription_intra_process.hpp

@@ -109,8 +109,14 @@ public:
 
     if (any_callback_.use_take_shared_method()) {
       shared_msg = this->buffer_->consume_shared();
+      if (!shared_msg) {
+        return nullptr;
+      }
     } else {
       unique_msg = this->buffer_->consume_unique();
+      if (!unique_msg) {
+        return nullptr;
+      }
     }
     return std::static_pointer_cast<void>(
       std::make_shared<std::pair<ConstMessageSharedPtr, MessageUniquePtr>>(
@@ -138,7 +144,7 @@ protected:
   execute_impl(std::shared_ptr<void> & data)
   {
     if (!data) {
-      throw std::runtime_error("'data' is empty");
+      return;
     }
 
     rmw_message_info_t msg_info;

rclcpp/include/rclcpp/experimental/subscription_intra_process_base.hpp

@@ -52,7 +52,7 @@ public:
   {}
 
   RCLCPP_PUBLIC
-  virtual ~SubscriptionIntraProcessBase();
+  virtual ~SubscriptionIntraProcessBase() = default;
 
   RCLCPP_PUBLIC
   size_t

rclcpp/include/rclcpp/generic_publisher.hpp

@@ -78,38 +78,12 @@ public:
       node_base,
       topic_name,
       *rclcpp::get_typesupport_handle(topic_type, "rosidl_typesupport_cpp", *ts_lib),
-      options.template to_rcl_publisher_options<rclcpp::SerializedMessage>(qos)),
+      options.template to_rcl_publisher_options<rclcpp::SerializedMessage>(qos),
+      // NOTE(methylDragon): Passing these args separately is necessary for event binding
+      options.event_callbacks,
+      options.use_default_callbacks),
     ts_lib_(ts_lib)
-  {
-    // This is unfortunately duplicated with the code in publisher.hpp.
-    // TODO(nnmm): Deduplicate by moving this into PublisherBase.
-    if (options.event_callbacks.deadline_callback) {
-      this->add_event_handler(
-        options.event_callbacks.deadline_callback,
-        RCL_PUBLISHER_OFFERED_DEADLINE_MISSED);
-    }
-    if (options.event_callbacks.liveliness_callback) {
-      this->add_event_handler(
-        options.event_callbacks.liveliness_callback,
-        RCL_PUBLISHER_LIVELINESS_LOST);
-    }
-    if (options.event_callbacks.incompatible_qos_callback) {
-      this->add_event_handler(
-        options.event_callbacks.incompatible_qos_callback,
-        RCL_PUBLISHER_OFFERED_INCOMPATIBLE_QOS);
-    } else if (options.use_default_callbacks) {
-      // Register default callback when not specified
-      try {
-        this->add_event_handler(
-          [this](QOSOfferedIncompatibleQoSInfo & info) {
-            this->default_incompatible_qos_callback(info);
-          },
-          RCL_PUBLISHER_OFFERED_INCOMPATIBLE_QOS);
-      } catch (UnsupportedEventTypeException & /*exc*/) {
-        // pass
-      }
-    }
-  }
+  {}
 
   RCLCPP_PUBLIC
   virtual ~GenericPublisher() = default;

rclcpp/include/rclcpp/generic_subscription.hpp

@@ -81,45 +81,13 @@ public:
       node_base,
       *rclcpp::get_typesupport_handle(topic_type, "rosidl_typesupport_cpp", *ts_lib),
       topic_name,
-      options.template to_rcl_subscription_options<rclcpp::SerializedMessage>(qos),
+      options.to_rcl_subscription_options(qos),
+      options.event_callbacks,
+      options.use_default_callbacks,
       true),
     callback_(callback),
     ts_lib_(ts_lib)
-  {
-    // This is unfortunately duplicated with the code in subscription.hpp.
-    // TODO(nnmm): Deduplicate by moving this into SubscriptionBase.
-    if (options.event_callbacks.deadline_callback) {
-      this->add_event_handler(
-        options.event_callbacks.deadline_callback,
-        RCL_SUBSCRIPTION_REQUESTED_DEADLINE_MISSED);
-    }
-    if (options.event_callbacks.liveliness_callback) {
-      this->add_event_handler(
-        options.event_callbacks.liveliness_callback,
-        RCL_SUBSCRIPTION_LIVELINESS_CHANGED);
-    }
-    if (options.event_callbacks.incompatible_qos_callback) {
-      this->add_event_handler(
-        options.event_callbacks.incompatible_qos_callback,
-        RCL_SUBSCRIPTION_REQUESTED_INCOMPATIBLE_QOS);
-    } else if (options.use_default_callbacks) {
-      // Register default callback when not specified
-      try {
-        this->add_event_handler(
-          [this](QOSRequestedIncompatibleQoSInfo & info) {
-            this->default_incompatible_qos_callback(info);
-          },
-          RCL_SUBSCRIPTION_REQUESTED_INCOMPATIBLE_QOS);
-      } catch (UnsupportedEventTypeException & /*exc*/) {
-        // pass
-      }
-    }
-    if (options.event_callbacks.message_lost_callback) {
-      this->add_event_handler(
-        options.event_callbacks.message_lost_callback,
-        RCL_SUBSCRIPTION_MESSAGE_LOST);
-    }
-  }
+  {}
 
   RCLCPP_PUBLIC
   virtual ~GenericSubscription() = default;

rclcpp/include/rclcpp/graph_listener.hpp

@@ -128,6 +128,11 @@ public:
    * If start_if_not_started() was never called, this function still succeeds,
    * but start_if_not_started() still cannot be called after this function.
    *
+   * Note that if you override this method, but leave shutdown to be called in
+   * the destruction of this base class, it will not call the overridden
+   * version from your base class.
+   * So you need to ensure you call your class's shutdown() in its destructor.
+   *
    * \throws rclcpp::execptions::RCLError from rcl_guard_condition_fini()
    * \throws rclcpp::execptions::RCLError from rcl_wait_set_fini()
    * \throws std::system_error anything std::mutex::lock() throws

rclcpp/include/rclcpp/guard_condition.hpp

@@ -72,7 +72,7 @@ public:
   const rcl_guard_condition_t &
   get_rcl_guard_condition() const;
 
-  /// Notify the wait set waiting on this condition, if any, that the condition had been met.
+  /// Signal that the condition has been met, notifying both the wait set and listeners, if any.
   /**
    * This function is thread-safe, and may be called concurrently with waiting
    * on this guard condition in a wait set.
@@ -107,6 +107,22 @@ public:
   void
   add_to_wait_set(rcl_wait_set_t * wait_set);
 
+  /// Set a callback to be called whenever the guard condition is triggered.
+  /**
+   * The callback receives a size_t which is the number of times the guard condition was triggered
+   * since the last time this callback was called.
+   * Normally this is 1, but can be > 1 if the guard condition was triggered before any
+   * callback was set.
+   *
+   * Calling it again will clear any previously set callback.
+   *
+   * This function is thread-safe.
+   *
+   * If you want more information available in the callback, like the guard condition
+   * or other information, you may use a lambda with captures or std::bind.
+   *
+   * \param[in] callback functor to be called when the guard condition is triggered
+   */
   RCLCPP_PUBLIC
   void
   set_on_trigger_callback(std::function<void(size_t)> callback);

rclcpp/include/rclcpp/logger.hpp

@@ -17,6 +17,7 @@
 
 #include <memory>
 #include <string>
+#include <utility>
 
 #include "rclcpp/visibility_control.hpp"
 
@@ -122,6 +123,7 @@ private:
   : name_(new std::string(name)) {}
 
   std::shared_ptr<const std::string> name_;
+  std::shared_ptr<std::pair<std::string, std::string>> logger_sublogger_pairname_ = nullptr;
 
 public:
   RCLCPP_PUBLIC
@@ -157,13 +159,7 @@ public:
    */
   RCLCPP_PUBLIC
   Logger
-  get_child(const std::string & suffix)
-  {
-    if (!name_) {
-      return Logger();
-    }
-    return Logger(*name_ + "." + suffix);
-  }
+  get_child(const std::string & suffix);
 
   /// Set level for current logger.
   /**

rclcpp/include/rclcpp/node.hpp

@@ -227,7 +227,7 @@ public:
     )
   );
 
-  /// Create a timer.
+  /// Create a wall timer that uses the wall clock to drive the callback.
   /**
    * \param[in] period Time interval between triggers of the callback.
    * \param[in] callback User-defined callback function.
@@ -240,18 +240,47 @@ public:
     CallbackT callback,
     rclcpp::CallbackGroup::SharedPtr group = nullptr);
 
+  /// Create a timer that uses the node clock to drive the callback.
+  /**
+   * \param[in] period Time interval between triggers of the callback.
+   * \param[in] callback User-defined callback function.
+   * \param[in] group Callback group to execute this timer's callback in.
+   */
+  template<typename DurationRepT = int64_t, typename DurationT = std::milli, typename CallbackT>
+  typename rclcpp::GenericTimer<CallbackT>::SharedPtr
+  create_timer(
+    std::chrono::duration<DurationRepT, DurationT> period,
+    CallbackT callback,
+    rclcpp::CallbackGroup::SharedPtr group = nullptr);
+
   /// Create and return a Client.
   /**
    * \param[in] service_name The topic to service on.
    * \param[in] qos_profile rmw_qos_profile_t Quality of service profile for client.
    * \param[in] group Callback group to call the service.
    * \return Shared pointer to the created client.
+   * \deprecated use rclcpp::QoS instead of rmw_qos_profile_t
+   */
+  template<typename ServiceT>
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
+  typename rclcpp::Client<ServiceT>::SharedPtr
+  create_client(
+    const std::string & service_name,
+    const rmw_qos_profile_t & qos_profile,
+    rclcpp::CallbackGroup::SharedPtr group = nullptr);
+
+  /// Create and return a Client.
+  /**
+   * \param[in] service_name The name on which the service is accessible.
+   * \param[in] qos Quality of service profile for client.
+   * \param[in] group Callback group to handle the reply to service calls.
+   * \return Shared pointer to the created client.
    */
   template<typename ServiceT>
   typename rclcpp::Client<ServiceT>::SharedPtr
   create_client(
     const std::string & service_name,
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_services_default,
+    const rclcpp::QoS & qos = rclcpp::ServicesQoS(),
     rclcpp::CallbackGroup::SharedPtr group = nullptr);
 
   /// Create and return a Service.
@@ -261,13 +290,31 @@ public:
    * \param[in] qos_profile rmw_qos_profile_t Quality of service profile for client.
    * \param[in] group Callback group to call the service.
    * \return Shared pointer to the created service.
+   * \deprecated use rclcpp::QoS instead of rmw_qos_profile_t
+   */
+  template<typename ServiceT, typename CallbackT>
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
+  typename rclcpp::Service<ServiceT>::SharedPtr
+  create_service(
+    const std::string & service_name,
+    CallbackT && callback,
+    const rmw_qos_profile_t & qos_profile,
+    rclcpp::CallbackGroup::SharedPtr group = nullptr);
+
+  /// Create and return a Service.
+  /**
+   * \param[in] service_name The topic to service on.
+   * \param[in] callback User-defined callback function.
+   * \param[in] qos Quality of service profile for the service.
+   * \param[in] group Callback group to call the service.
+   * \return Shared pointer to the created service.
    */
   template<typename ServiceT, typename CallbackT>
   typename rclcpp::Service<ServiceT>::SharedPtr
   create_service(
     const std::string & service_name,
     CallbackT && callback,
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_services_default,
+    const rclcpp::QoS & qos = rclcpp::ServicesQoS(),
     rclcpp::CallbackGroup::SharedPtr group = nullptr);
 
   /// Create and return a GenericPublisher.
@@ -336,11 +383,21 @@ public:
    *
    * If `ignore_override` is `true`, the parameter override will be ignored.
    *
-   * This method, if successful, will result in any callback registered with
-   * add_on_set_parameters_callback to be called.
+   * This method will result in any callback registered with
+   * `add_on_set_parameters_callback` and `add_post_set_parameters_callback`
+   * to be called for the parameter being set.
+   *
+   * If a callback was registered previously with `add_on_set_parameters_callback`,
+   * it will be called prior to setting the parameter for the node.
    * If that callback prevents the initial value for the parameter from being
    * set then rclcpp::exceptions::InvalidParameterValueException is thrown.
    *
+   * If a callback was registered previously with `add_post_set_parameters_callback`,
+   * it will be called after setting the parameter successfully for the node.
+   *
+   * This method will _not_ result in any callbacks registered with
+   * `add_pre_set_parameters_callback` to be called.
+   *
    * The returned reference will remain valid until the parameter is
    * undeclared.
    *
@@ -457,11 +514,22 @@ public:
    * If `ignore_overrides` is `true`, all the overrides of the parameters declared
    * by the function call will be ignored.
    *
+   * This method will result in any callback registered with
+   * `add_on_set_parameters_callback` and `add_post_set_parameters_callback`
+   * to be called once for each parameter.
+   *
    * This method, if successful, will result in any callback registered with
-   * add_on_set_parameters_callback to be called, once for each parameter.
+   * `add_on_set_parameters_callback` to be called, once for each parameter.
    * If that callback prevents the initial value for any parameter from being
    * set then rclcpp::exceptions::InvalidParameterValueException is thrown.
    *
+   * If a callback was registered previously with `add_post_set_parameters_callback`,
+   * it will be called after setting the parameters successfully for the node,
+   * once for each parameter.
+   *
+   * This method will _not_ result in any callbacks registered with
+   * `add_pre_set_parameters_callback` to be called.
+   *
    * \param[in] namespace_ The namespace in which to declare the parameters.
    * \param[in] parameters The parameters to set in the given namespace.
    * \param[in] ignore_overrides When `true`, the parameters overrides are ignored.
@@ -499,8 +567,9 @@ public:
 
   /// Undeclare a previously declared parameter.
   /**
-   * This method will not cause a callback registered with
-   * add_on_set_parameters_callback to be called.
+   * This method will _not_ cause a callback registered with any of the
+   * `add_pre_set_parameters_callback`, `add_on_set_parameters_callback` and
+   * `add_post_set_parameters_callback` to be called.
    *
    * \param[in] name The name of the parameter to be undeclared.
    * \throws rclcpp::exceptions::ParameterNotDeclaredException if the parameter
@@ -534,11 +603,24 @@ public:
    * Parameter overrides are ignored by set_parameter.
    *
    * This method will result in any callback registered with
-   * add_on_set_parameters_callback to be called.
+   * `add_pre_set_parameters_callback`, add_on_set_parameters_callback` and
+   * `add_post_set_parameters_callback` to be called once for the parameter
+   * being set.
+   *
+   * This method will result in any callback registered with
+   * `add_on_set_parameters_callback` to be called.
    * If the callback prevents the parameter from being set, then it will be
    * reflected in the SetParametersResult that is returned, but no exception
    * will be thrown.
    *
+   * If a callback was registered previously with `add_pre_set_parameters_callback`,
+   * it will be called once prior to the validation of the parameter for the node.
+   * If this callback makes modified parameter list empty, then it will be reflected
+   * in the returned result; no exceptions will be raised in this case.
+   *
+   * If a callback was registered previously with `add_post_set_parameters_callback`,
+   * it will be called once after setting the parameter successfully for the node.
+   *
    * If the value type of the parameter is rclcpp::PARAMETER_NOT_SET, and the
    * existing parameter type is something else, then the parameter will be
    * implicitly undeclared.
@@ -575,11 +657,25 @@ public:
    * corresponding SetParametersResult in the vector returned by this function.
    *
    * This method will result in any callback registered with
-   * add_on_set_parameters_callback to be called, once for each parameter.
+   * `add_pre_set_parameters_callback`, `add_on_set_parameters_callback` and
+   * `add_post_set_parameters_callback` to be called once for each parameter.
+
+   * If a callback was registered previously with `add_pre_set_parameters_callback`,
+   * it will be called prior to the validation of parameters for the node,
+   * once for each parameter.
+   * If this callback makes modified parameter list empty, then it will be reflected
+   * in the returned result; no exceptions will be raised in this case.
+   *
+   * This method will result in any callback registered with
+   * `add_on_set_parameters_callback` to be called, once for each parameter.
    * If the callback prevents the parameter from being set, then, as mentioned
    * before, it will be reflected in the corresponding SetParametersResult
    * that is returned, but no exception will be thrown.
    *
+   * If a callback was registered previously with `add_post_set_parameters_callback`,
+   * it will be called after setting the parameters successfully for the node,
+   * once for each parameter.
+   *
    * Like set_parameter() this method will implicitly undeclare parameters
    * with the type rclcpp::PARAMETER_NOT_SET.
    *
@@ -606,11 +702,25 @@ public:
    * If the exception is thrown then none of the parameters will have been set.
    *
    * This method will result in any callback registered with
-   * add_on_set_parameters_callback to be called, just one time.
+   * `add_pre_set_parameters_callback`, `add_on_set_parameters_callback` and
+   * `add_post_set_parameters_callback` to be called only 'once' for all parameters.
+   *
+   * If a callback was registered previously with `add_pre_set_parameters_callback`,
+   * it will be called prior to the validation of node parameters, just one time
+   * for all parameters.
+   * If this callback makes modified parameter list empty, then it will be reflected
+   * in the returned result; no exceptions will be raised in this case.
+   *
+   * This method will result in any callback registered with
+   * 'add_on_set_parameters_callback' to be called, just one time.
    * If the callback prevents the parameters from being set, then it will be
    * reflected in the SetParametersResult which is returned, but no exception
    * will be thrown.
    *
+   * If a callback was registered previously with `add_post_set_parameters_callback`,
+   * it will be called after setting the node parameters successfully, just one time
+   * for all parameters.
+   *
    * If you pass multiple rclcpp::Parameter instances with the same name, then
    * only the last one in the vector (forward iteration) will be set.
    *
@@ -630,17 +740,21 @@ public:
   /**
    * If the parameter has not been declared, then this method may throw the
    * rclcpp::exceptions::ParameterNotDeclaredException exception.
+   * If the parameter has not been initialized, then this method may throw the
+   * rclcpp::exceptions::ParameterUninitializedException exception.
    *
    * If undeclared parameters are allowed, see the node option
    * rclcpp::NodeOptions::allow_undeclared_parameters, then this method will
-   * not throw an exception, and instead return a default initialized
-   * rclcpp::Parameter, which has a type of
+   * not throw the rclcpp::exceptions::ParameterNotDeclaredException exception,
+   * and instead return a default initialized rclcpp::Parameter, which has a type of
    * rclcpp::ParameterType::PARAMETER_NOT_SET.
    *
    * \param[in] name The name of the parameter to get.
    * \return The requested parameter inside of a rclcpp parameter object.
    * \throws rclcpp::exceptions::ParameterNotDeclaredException if the parameter
    *   has not been declared and undeclared parameters are not allowed.
+   * \throws rclcpp::exceptions::ParameterUninitializedException if the parameter
+   *   has not been initialized.
    */
   RCLCPP_PUBLIC
   rclcpp::Parameter
@@ -724,12 +838,12 @@ public:
 
   /// Return the parameters by the given parameter names.
   /**
-   * Like get_parameters(), this method may throw the
+   * Like get_parameter(const std::string &), this method may throw the
    * rclcpp::exceptions::ParameterNotDeclaredException exception if the
    * requested parameter has not been declared and undeclared parameters are
-   * not allowed.
+   * not allowed, and may throw the rclcpp::exceptions::ParameterUninitializedException exception.
    *
-   * Also like get_parameters(), if undeclared parameters are allowed and the
+   * Also like get_parameter(const std::string &), if undeclared parameters are allowed and the
    * parameter has not been declared, then the corresponding rclcpp::Parameter
    * will be default initialized and therefore have the type
    * rclcpp::ParameterType::PARAMETER_NOT_SET.
@@ -739,6 +853,8 @@ public:
    * \throws rclcpp::exceptions::ParameterNotDeclaredException if any of the
    *   parameters have not been declared and undeclared parameters are not
    *   allowed.
+   * \throws rclcpp::exceptions::ParameterUninitializedException if any of the
+   *   parameters have not been initialized.
    */
   RCLCPP_PUBLIC
   std::vector<rclcpp::Parameter>
@@ -859,12 +975,85 @@ public:
   rcl_interfaces::msg::ListParametersResult
   list_parameters(const std::vector<std::string> & prefixes, uint64_t depth) const;
 
+  using PreSetParametersCallbackHandle =
+    rclcpp::node_interfaces::PreSetParametersCallbackHandle;
+  using PreSetParametersCallbackType =
+    rclcpp::node_interfaces::NodeParametersInterface::PreSetParametersCallbackType;
+
   using OnSetParametersCallbackHandle =
     rclcpp::node_interfaces::OnSetParametersCallbackHandle;
-  using OnParametersSetCallbackType =
-    rclcpp::node_interfaces::NodeParametersInterface::OnParametersSetCallbackType;
+  using OnSetParametersCallbackType =
+    rclcpp::node_interfaces::NodeParametersInterface::OnSetParametersCallbackType;
+  using OnParametersSetCallbackType [[deprecated("use OnSetParametersCallbackType instead")]] =
+    OnSetParametersCallbackType;
 
-  /// Add a callback for when parameters are being set.
+  using PostSetParametersCallbackHandle =
+    rclcpp::node_interfaces::PostSetParametersCallbackHandle;
+  using PostSetParametersCallbackType =
+    rclcpp::node_interfaces::NodeParametersInterface::PostSetParametersCallbackType;
+
+  /// Add a callback that gets triggered before parameters are validated.
+  /**
+   * This callback can be used to modify the original list of parameters being
+   * set by the user.
+   *
+   * The modified list of parameters is then forwarded to the "on set parameter"
+   * callback for validation.
+   *
+   * The callback is called whenever any of the `set_parameter*` methods are called
+   * or when a set parameter service request is received.
+   *
+   * The callback takes a reference to the vector of parameters to be set.
+   *
+   * The vector of parameters may be modified by the callback.
+   *
+   * One of the use case of "pre set callback" can be updating additional parameters
+   * conditioned on changes to a parameter.
+   *
+   * Users should retain a copy of the returned shared pointer, as the callback
+   * is valid only as long as the smart pointer is alive.
+   *
+   * For an example callback:
+   *
+   *```cpp
+   * void
+   * preSetParameterCallback(std::vector<rclcpp::Parameter> & parameters)
+   * {
+   *  for (auto & param : parameters) {
+   *    if (param.get_name() == "param1") {
+   *      parameters.push_back(rclcpp::Parameter("param2", 4.0));
+   *    }
+   *  }
+   * }
+   * ```
+   * The above callback appends 'param2' to the list of parameters to be set if
+   * 'param1' is being set by the user.
+   *
+   * All parameters in the vector will be set atomically.
+   *
+   * Note that the callback is only called while setting parameters with `set_parameter`,
+   * `set_parameters`, `set_parameters_atomically`, or externally with a parameters service.
+   *
+   * The callback is not called when parameters are declared with `declare_parameter`
+   * or `declare_parameters`.
+   *
+   * The callback is not called when parameters are undeclared with `undeclare_parameter`.
+   *
+   * An empty modified parameter list from the callback will result in "set_parameter*"
+   * returning an unsuccessful result.
+   *
+   * The `remove_pre_set_parameters_callback` can be used to deregister the callback.
+   *
+   * \param callback The callback to register.
+   * \returns A shared pointer. The callback is valid as long as the smart pointer is alive.
+   * \throws std::bad_alloc if the allocation of the PreSetParametersCallbackHandle fails.
+   */
+  RCLCPP_PUBLIC
+  RCUTILS_WARN_UNUSED
+  PreSetParametersCallbackHandle::SharedPtr
+  add_pre_set_parameters_callback(PreSetParametersCallbackType callback);
+
+  /// Add a callback to validate parameters before they are set.
   /**
    * The callback signature is designed to allow handling of any of the above
    * `set_parameter*` or `declare_parameter*` methods, and so it takes a const
@@ -872,6 +1061,9 @@ public:
    * rcl_interfaces::msg::SetParametersResult to indicate whether or not the
    * parameter should be set or not, and if not why.
    *
+   * Users should retain a copy of the returned shared pointer, as the callback
+   * is valid only as long as the smart pointer is alive.
+   *
    * For an example callback:
    *
    * ```cpp
@@ -903,6 +1095,8 @@ public:
    * this callback, so when checking a new value against the existing one, you
    * must account for the case where the parameter is not yet set.
    *
+   * The callback is not called when parameters are undeclared with `undeclare_parameter`.
+   *
    * Some constraints like read_only are enforced before the callback is called.
    *
    * The callback may introspect other already set parameters (by calling any
@@ -931,7 +1125,80 @@ public:
   RCLCPP_PUBLIC
   RCUTILS_WARN_UNUSED
   OnSetParametersCallbackHandle::SharedPtr
-  add_on_set_parameters_callback(OnParametersSetCallbackType callback);
+  add_on_set_parameters_callback(OnSetParametersCallbackType callback);
+
+  /// Add a callback that gets triggered after parameters are set successfully.
+  /**
+   * The callback is called when any of the `set_parameter*` or `declare_parameter*`
+   * methods are successful.
+   *
+   * Users should retain a copy of the returned shared pointer, as the callback
+   * is valid only as long as the smart pointer is alive.
+   *
+   * The callback takes a reference to a const vector of parameters that have been
+   * set successfully.
+   *
+   * The post callback can be valuable as a place to cause side-effects based on
+   * parameter changes.
+   * For instance updating internally tracked class attributes once parameters
+   * have been changed successfully.
+   *
+   * For an example callback:
+   *
+   * ```cpp
+   * void
+   * postSetParameterCallback(const std::vector<rclcpp::Parameter> & parameters)
+   * {
+   *  for(const auto & param:parameters) {
+   *   // the internal class member can be changed after
+   *   // successful change to param1 or param2
+   *    if(param.get_name() == "param1") {
+   *      internal_tracked_class_parameter_1_ = param.get_value<double>();
+   *    }
+   *    else if(param.get_name() == "param2") {
+   *      internal_tracked_class_parameter_2_ = param.get_value<double>();
+   *    }
+   *  }
+   * }
+   * ```
+   *
+   * The above callback takes a const reference to list of parameters that have been
+   * set successfully and as a result of this updates the internally tracked class attributes
+   * `internal_tracked_class_parameter_1_` and `internal_tracked_class_parameter_2_`
+   * respectively.
+   *
+   * This callback should not modify parameters.
+   *
+   * The callback is called when parameters are declared with `declare_parameter`
+   * or `declare_parameters`. See `declare_parameter` or `declare_parameters` above.
+   *
+   * The callback is not called when parameters are undeclared with `undeclare_parameter`.
+   *
+   * If you want to make changes to parameters based on changes to another, use
+   * `add_pre_set_parameters_callback`.
+   *
+   * The `remove_post_set_parameters_callback` can be used to deregister the callback.
+   *
+   * \param callback The callback to register.
+   * \returns A shared pointer. The callback is valid as long as the smart pointer is alive.
+   * \throws std::bad_alloc if the allocation of the OnSetParametersCallbackHandle fails.
+   */
+  RCLCPP_PUBLIC
+  RCUTILS_WARN_UNUSED
+  PostSetParametersCallbackHandle::SharedPtr
+  add_post_set_parameters_callback(PostSetParametersCallbackType callback);
+
+  /// Remove a callback registered with `add_pre_set_parameters_callback`.
+  /**
+   * Delete a handler returned by `add_pre_set_parameters_callback`.
+   *
+   * \param handler The callback handler to remove.
+   * \throws std::runtime_error if the handler was not created with `add_pre_set_parameters_callback`,
+   *   or if it has been removed before.
+   */
+  RCLCPP_PUBLIC
+  void
+  remove_pre_set_parameters_callback(const PreSetParametersCallbackHandle * const handler);
 
   /// Remove a callback registered with `add_on_set_parameters_callback`.
   /**
@@ -960,6 +1227,18 @@ public:
   void
   remove_on_set_parameters_callback(const OnSetParametersCallbackHandle * const handler);
 
+  /// Remove a callback registered with `add_post_set_parameters_callback`.
+  /**
+   * Delete a handler returned by `add_post_set_parameters_callback`.
+   *
+   * \param handler The callback handler to remove.
+   * \throws std::runtime_error if the handler was not created with `add_post_set_parameters_callback`,
+   *   or if it has been removed before.
+   */
+  RCLCPP_PUBLIC
+  void
+  remove_post_set_parameters_callback(const PostSetParametersCallbackHandle * const handler);
+
   /// Get the fully-qualified names of all available nodes.
   /**
    * The fully-qualified name includes the local namespace and name of the node.

rclcpp/include/rclcpp/node_impl.hpp

@@ -120,6 +120,38 @@ Node::create_wall_timer(
     this->node_timers_.get());
 }
 
+template<typename DurationRepT, typename DurationT, typename CallbackT>
+typename rclcpp::GenericTimer<CallbackT>::SharedPtr
+Node::create_timer(
+  std::chrono::duration<DurationRepT, DurationT> period,
+  CallbackT callback,
+  rclcpp::CallbackGroup::SharedPtr group)
+{
+  return rclcpp::create_timer(
+    this->get_clock(),
+    period,
+    std::move(callback),
+    group,
+    this->node_base_.get(),
+    this->node_timers_.get());
+}
+
+template<typename ServiceT>
+typename Client<ServiceT>::SharedPtr
+Node::create_client(
+  const std::string & service_name,
+  const rclcpp::QoS & qos,
+  rclcpp::CallbackGroup::SharedPtr group)
+{
+  return rclcpp::create_client<ServiceT>(
+    node_base_,
+    node_graph_,
+    node_services_,
+    extend_name_with_sub_namespace(service_name, this->get_sub_namespace()),
+    qos,
+    group);
+}
+
 template<typename ServiceT>
 typename Client<ServiceT>::SharedPtr
 Node::create_client(
@@ -136,6 +168,23 @@ Node::create_client(
     group);
 }
 
+template<typename ServiceT, typename CallbackT>
+typename rclcpp::Service<ServiceT>::SharedPtr
+Node::create_service(
+  const std::string & service_name,
+  CallbackT && callback,
+  const rclcpp::QoS & qos,
+  rclcpp::CallbackGroup::SharedPtr group)
+{
+  return rclcpp::create_service<ServiceT, CallbackT>(
+    node_base_,
+    node_services_,
+    extend_name_with_sub_namespace(service_name, this->get_sub_namespace()),
+    std::forward<CallbackT>(callback),
+    qos,
+    group);
+}
+
 template<typename ServiceT, typename CallbackT>
 typename rclcpp::Service<ServiceT>::SharedPtr
 Node::create_service(

rclcpp/include/rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp

@@ -0,0 +1,208 @@
+// Copyright 2022 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__NODE_INTERFACES__DETAIL__NODE_INTERFACES_HELPERS_HPP_
+#define RCLCPP__NODE_INTERFACES__DETAIL__NODE_INTERFACES_HELPERS_HPP_
+
+#include <memory>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+namespace node_interfaces
+{
+namespace detail
+{
+
+// Support and Helper template classes for the NodeInterfaces class.
+
+template<typename NodeT, typename ... Ts>
+std::tuple<std::shared_ptr<Ts>...>
+init_tuple(NodeT & n);
+
+/// Stores the interfaces in a tuple, provides constructors, and getters.
+template<typename ... InterfaceTs>
+struct NodeInterfacesStorage
+{
+  template<typename NodeT>
+  NodeInterfacesStorage(NodeT & node)  // NOLINT(runtime/explicit)
+  : interfaces_(init_tuple<decltype(node), InterfaceTs ...>(node))
+  {}
+
+  NodeInterfacesStorage()
+  : interfaces_()
+  {}
+
+  explicit NodeInterfacesStorage(std::shared_ptr<InterfaceTs>... args)
+  : interfaces_(args ...)
+  {}
+
+  /// Individual Node Interface non-const getter.
+  template<typename NodeInterfaceT>
+  std::shared_ptr<NodeInterfaceT>
+  get()
+  {
+    static_assert(
+      (std::is_same_v<NodeInterfaceT, InterfaceTs>|| ...),
+      "NodeInterfaces class does not contain given NodeInterfaceT");
+    return std::get<std::shared_ptr<NodeInterfaceT>>(interfaces_);
+  }
+
+  /// Individual Node Interface const getter.
+  template<typename NodeInterfaceT>
+  std::shared_ptr<const NodeInterfaceT>
+  get() const
+  {
+    static_assert(
+      (std::is_same_v<NodeInterfaceT, InterfaceTs>|| ...),
+      "NodeInterfaces class does not contain given NodeInterfaceT");
+    return std::get<std::shared_ptr<NodeInterfaceT>>(interfaces_);
+  }
+
+protected:
+  std::tuple<std::shared_ptr<InterfaceTs>...> interfaces_;
+};
+
+/// Prototype of NodeInterfacesSupports.
+/**
+ * Should read NodeInterfacesSupports<..., T, ...> as "NodeInterfaces supports T", and
+ * if NodeInterfacesSupport is specialized for T, the is_supported should be
+ * set to std::true_type, but by default it is std::false_type, which will
+ * lead to a compiler error when trying to use T with NodeInterfaces.
+ */
+template<typename StorageClassT, typename ... Ts>
+struct NodeInterfacesSupports;
+
+/// Prototype of NodeInterfacesSupportCheck template meta-function.
+/**
+ * This meta-function checks that all the types given are supported,
+ * throwing a more human-readable error if an unsupported type is used.
+ */
+template<typename StorageClassT, typename ... InterfaceTs>
+struct NodeInterfacesSupportCheck;
+
+/// Iterating specialization that ensures classes are supported and inherited.
+template<typename StorageClassT, typename NextInterfaceT, typename ... RemainingInterfaceTs>
+struct NodeInterfacesSupportCheck<StorageClassT, NextInterfaceT, RemainingInterfaceTs ...>
+  : public NodeInterfacesSupportCheck<StorageClassT, RemainingInterfaceTs ...>
+{
+  static_assert(
+    NodeInterfacesSupports<StorageClassT, NextInterfaceT>::is_supported::value,
+    "given NodeInterfaceT is not supported by rclcpp::node_interfaces::NodeInterfaces");
+};
+
+/// Terminating case when there are no more "RemainingInterfaceTs".
+template<typename StorageClassT>
+struct NodeInterfacesSupportCheck<StorageClassT>
+{};
+
+/// Default specialization, needs to be specialized for each supported interface.
+template<typename StorageClassT, typename ... RemainingInterfaceTs>
+struct NodeInterfacesSupports
+{
+  // Specializations need to set this to std::true_type in addition to other interfaces.
+  using is_supported = std::false_type;
+};
+
+/// Terminating specialization of NodeInterfacesSupports.
+template<typename StorageClassT>
+struct NodeInterfacesSupports<StorageClassT>
+  : public StorageClassT
+{
+  /// Perfect forwarding constructor to get arguments down to StorageClassT.
+  template<typename ... ArgsT>
+  explicit NodeInterfacesSupports(ArgsT && ... args)
+  : StorageClassT(std::forward<ArgsT>(args) ...)
+  {}
+};
+
+// Helper functions to initialize the tuple in NodeInterfaces.
+
+template<typename StorageClassT, typename ElementT, typename TupleT, typename NodeT>
+void
+init_element(TupleT & t, NodeT & n)
+{
+  std::get<std::shared_ptr<ElementT>>(t) =
+    NodeInterfacesSupports<StorageClassT, ElementT>::get_from_node_like(n);
+}
+
+template<typename NodeT, typename ... Ts>
+std::tuple<std::shared_ptr<Ts>...>
+init_tuple(NodeT & n)
+{
+  using StorageClassT = NodeInterfacesStorage<Ts ...>;
+  std::tuple<std::shared_ptr<Ts>...> t;
+  (init_element<StorageClassT, Ts>(t, n), ...);
+  return t;
+}
+
+/// Macro for creating specializations with less boilerplate.
+/**
+ * You can use this macro to add support for your interface class if:
+ *
+ * - The standard getter is get_node_{NodeInterfaceName}_interface(), and
+ * - the getter returns a non-const shared_ptr<{NodeInterfaceType}>
+ *
+ * Examples of using this can be seen in the standard node interface headers
+ * in rclcpp, e.g. rclcpp/node_interfaces/node_base_interface.hpp has:
+ *
+ *   RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeBaseInterface, base)
+ *
+ * If your interface has a non-standard getter, or you want to instrument it or
+ * something like that, then you'll need to create your own specialization of
+ * the NodeInterfacesSupports struct without this macro.
+ */
+#define RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(NodeInterfaceType, NodeInterfaceName) \
+  namespace rclcpp::node_interfaces::detail { \
+  template<typename StorageClassT, typename ... RemainingInterfaceTs> \
+  struct NodeInterfacesSupports< \
+    StorageClassT, \
+    NodeInterfaceType, \
+    RemainingInterfaceTs ...> \
+    : public NodeInterfacesSupports<StorageClassT, RemainingInterfaceTs ...> \
+  { \
+    using is_supported = std::true_type; \
+ \
+    template<typename NodeT> \
+    static \
+    std::shared_ptr<NodeInterfaceType> \
+    get_from_node_like(NodeT & node_like) \
+    { \
+      return node_like.get_node_ ## NodeInterfaceName ## _interface(); \
+    } \
+ \
+    /* Perfect forwarding constructor to get arguments down to StorageClassT (eventually). */ \
+    template<typename ... ArgsT> \
+    explicit NodeInterfacesSupports(ArgsT && ... args) \
+      : NodeInterfacesSupports<StorageClassT, RemainingInterfaceTs ...>( \
+        std::forward<ArgsT>(args) ...) \
+    {} \
+ \
+    std::shared_ptr<NodeInterfaceType> \
+    get_node_ ## NodeInterfaceName ## _interface() \
+    { \
+      return StorageClassT::template get<NodeInterfaceType>(); \
+    } \
+  }; \
+  }  // namespace rclcpp::node_interfaces::detail
+
+}  // namespace detail
+}  // namespace node_interfaces
+}  // namespace rclcpp
+
+#endif  // RCLCPP__NODE_INTERFACES__DETAIL__NODE_INTERFACES_HELPERS_HPP_

rclcpp/include/rclcpp/node_interfaces/node_base.hpp

@@ -15,7 +15,7 @@
 #ifndef RCLCPP__NODE_INTERFACES__NODE_BASE_HPP_
 #define RCLCPP__NODE_INTERFACES__NODE_BASE_HPP_
 
-#include <functional>
+#include <atomic>
 #include <memory>
 #include <mutex>
 #include <string>
@@ -39,6 +39,13 @@ class NodeBase : public NodeBaseInterface, public std::enable_shared_from_this<N
 public:
   RCLCPP_SMART_PTR_ALIASES_ONLY(NodeBase)
 
+  /// Constructor.
+  /**
+   * If nullptr (default) is given for the default_callback_group, one will
+   * be created by the constructor using the create_callback_group() method,
+   * but virtual dispatch will not occur so overrides of that method will not
+   * be used.
+   */
   RCLCPP_PUBLIC
   NodeBase(
     const std::string & node_name,
@@ -46,7 +53,8 @@ public:
     rclcpp::Context::SharedPtr context,
     const rcl_node_options_t & rcl_node_options,
     bool use_intra_process_default,
-    bool enable_topic_statistics_default);
+    bool enable_topic_statistics_default,
+    rclcpp::CallbackGroup::SharedPtr default_callback_group = nullptr);
 
   RCLCPP_PUBLIC
   virtual

rclcpp/include/rclcpp/node_interfaces/node_base_interface.hpp

@@ -15,10 +15,10 @@
 #ifndef RCLCPP__NODE_INTERFACES__NODE_BASE_INTERFACE_HPP_
 #define RCLCPP__NODE_INTERFACES__NODE_BASE_INTERFACE_HPP_
 
+#include <atomic>
+#include <functional>
 #include <memory>
-#include <mutex>
 #include <string>
-#include <vector>
 
 #include "rcl/node.h"
 
@@ -26,6 +26,7 @@
 #include "rclcpp/context.hpp"
 #include "rclcpp/guard_condition.hpp"
 #include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
 #include "rclcpp/visibility_control.hpp"
 
 namespace rclcpp
@@ -177,4 +178,6 @@ public:
 }  // namespace node_interfaces
 }  // namespace rclcpp
 
+RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeBaseInterface, base)
+
 #endif  // RCLCPP__NODE_INTERFACES__NODE_BASE_INTERFACE_HPP_

rclcpp/include/rclcpp/node_interfaces/node_clock.hpp

@@ -15,6 +15,7 @@
 #ifndef RCLCPP__NODE_INTERFACES__NODE_CLOCK_HPP_
 #define RCLCPP__NODE_INTERFACES__NODE_CLOCK_HPP_
 
+#include "rcl/time.h"
 #include "rclcpp/clock.hpp"
 #include "rclcpp/macros.hpp"
 #include "rclcpp/node_interfaces/node_base_interface.hpp"
@@ -42,7 +43,8 @@ public:
     rclcpp::node_interfaces::NodeTopicsInterface::SharedPtr node_topics,
     rclcpp::node_interfaces::NodeGraphInterface::SharedPtr node_graph,
     rclcpp::node_interfaces::NodeServicesInterface::SharedPtr node_services,
-    rclcpp::node_interfaces::NodeLoggingInterface::SharedPtr node_logging);
+    rclcpp::node_interfaces::NodeLoggingInterface::SharedPtr node_logging,
+    rcl_clock_type_t clock_type);
 
   RCLCPP_PUBLIC
   virtual
@@ -67,7 +69,7 @@ private:
   rclcpp::node_interfaces::NodeServicesInterface::SharedPtr node_services_;
   rclcpp::node_interfaces::NodeLoggingInterface::SharedPtr node_logging_;
 
-  rclcpp::Clock::SharedPtr ros_clock_;
+  rclcpp::Clock::SharedPtr clock_;
 };
 
 }  // namespace node_interfaces

rclcpp/include/rclcpp/node_interfaces/node_clock_interface.hpp

@@ -17,6 +17,7 @@
 
 #include "rclcpp/clock.hpp"
 #include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
 #include "rclcpp/visibility_control.hpp"
 
 namespace rclcpp
@@ -50,4 +51,6 @@ public:
 }  // namespace node_interfaces
 }  // namespace rclcpp
 
+RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeClockInterface, clock)
+
 #endif  // RCLCPP__NODE_INTERFACES__NODE_CLOCK_INTERFACE_HPP_

rclcpp/include/rclcpp/node_interfaces/node_graph.hpp

@@ -15,7 +15,9 @@
 #ifndef RCLCPP__NODE_INTERFACES__NODE_GRAPH_HPP_
 #define RCLCPP__NODE_INTERFACES__NODE_GRAPH_HPP_
 
+#include <atomic>
 #include <chrono>
+#include <condition_variable>
 #include <map>
 #include <memory>
 #include <mutex>

rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp

@@ -29,6 +29,7 @@
 
 #include "rclcpp/event.hpp"
 #include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
 #include "rclcpp/qos.hpp"
 #include "rclcpp/visibility_control.hpp"
 
@@ -382,4 +383,6 @@ public:
 }  // namespace node_interfaces
 }  // namespace rclcpp
 
+RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeGraphInterface, graph)
+
 #endif  // RCLCPP__NODE_INTERFACES__NODE_GRAPH_INTERFACE_HPP_

rclcpp/include/rclcpp/node_interfaces/node_interfaces.hpp

@@ -0,0 +1,164 @@
+// Copyright 2022 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__NODE_INTERFACES__NODE_INTERFACES_HPP_
+#define RCLCPP__NODE_INTERFACES__NODE_INTERFACES_HPP_
+
+#include <memory>
+
+#include "rclcpp/detail/template_unique.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
+
+#define ALL_RCLCPP_NODE_INTERFACES \
+  rclcpp::node_interfaces::NodeBaseInterface, \
+  rclcpp::node_interfaces::NodeClockInterface, \
+  rclcpp::node_interfaces::NodeGraphInterface, \
+  rclcpp::node_interfaces::NodeLoggingInterface, \
+  rclcpp::node_interfaces::NodeParametersInterface, \
+  rclcpp::node_interfaces::NodeServicesInterface, \
+  rclcpp::node_interfaces::NodeTimeSourceInterface, \
+  rclcpp::node_interfaces::NodeTimersInterface, \
+  rclcpp::node_interfaces::NodeTopicsInterface, \
+  rclcpp::node_interfaces::NodeWaitablesInterface
+
+
+namespace rclcpp
+{
+namespace node_interfaces
+{
+
+
+/// A helper class for aggregating node interfaces.
+template<typename ... InterfaceTs>
+class NodeInterfaces
+  : public detail::NodeInterfacesSupportCheck<
+    detail::NodeInterfacesStorage<InterfaceTs ...>,
+    InterfaceTs ...
+  >,
+  public detail::NodeInterfacesSupports<
+    detail::NodeInterfacesStorage<InterfaceTs ...>,
+    InterfaceTs ...
+  >
+{
+  static_assert(
+    0 != sizeof ...(InterfaceTs),
+    "must provide at least one interface as a template argument");
+  static_assert(
+    rclcpp::detail::template_unique_v<InterfaceTs ...>,
+    "must provide unique template parameters");
+
+  using NodeInterfacesSupportsT = detail::NodeInterfacesSupports<
+    detail::NodeInterfacesStorage<InterfaceTs ...>,
+    InterfaceTs ...
+  >;
+
+public:
+  /// Create a new NodeInterfaces object using the given node-like object's interfaces.
+  /**
+   * Specify which interfaces you need by passing them as template parameters.
+   *
+   * This allows you to aggregate interfaces from different sources together to pass as a single
+   * aggregate object to any functions that take node interfaces or node-likes, without needing to
+   * templatize that function.
+   *
+   * You may also use this constructor to create a NodeInterfaces that contains a subset of
+   * another NodeInterfaces' interfaces.
+   *
+   * Finally, this class supports implicit conversion from node-like objects, allowing you to
+   * directly pass a node-like to a function that takes a NodeInterfaces object.
+   *
+   * Usage examples:
+   *   ```cpp
+   *   // Suppose we have some function:
+   *   void fn(NodeInterfaces<NodeBaseInterface, NodeClockInterface> interfaces);
+   *
+   *   // Then we can, explicitly:
+   *   rclcpp::Node node("some_node");
+   *   auto ni = NodeInterfaces<NodeBaseInterface, NodeClockInterface>(node);
+   *   fn(ni);
+   *
+   *   // But also:
+   *   fn(node);
+   *
+   *   // Subsetting a NodeInterfaces object also works!
+   *   auto ni_base = NodeInterfaces<NodeBaseInterface>(ni);
+   *
+   *   // Or aggregate them (you could aggregate interfaces from disparate node-likes)
+   *   auto ni_aggregated = NodeInterfaces<NodeBaseInterface, NodeClockInterface>(
+   *     node->get_node_base_interface(),
+   *     node->get_node_clock_interface()
+   *   )
+   *
+   *   // And then to access the interfaces:
+   *   // Get with get<>
+   *   auto base = ni.get<NodeBaseInterface>();
+   *
+   *   // Or the appropriate getter
+   *   auto clock = ni.get_clock_interface();
+   *   ```
+   *
+   * You may use any of the standard node interfaces that come with rclcpp:
+   *   - rclcpp::node_interfaces::NodeBaseInterface
+   *   - rclcpp::node_interfaces::NodeClockInterface
+   *   - rclcpp::node_interfaces::NodeGraphInterface
+   *   - rclcpp::node_interfaces::NodeLoggingInterface
+   *   - rclcpp::node_interfaces::NodeParametersInterface
+   *   - rclcpp::node_interfaces::NodeServicesInterface
+   *   - rclcpp::node_interfaces::NodeTimeSourceInterface
+   *   - rclcpp::node_interfaces::NodeTimersInterface
+   *   - rclcpp::node_interfaces::NodeTopicsInterface
+   *   - rclcpp::node_interfaces::NodeWaitablesInterface
+   *
+   * Or you use custom interfaces as long as you make a template specialization
+   * of the rclcpp::node_interfaces::detail::NodeInterfacesSupport struct using
+   * the RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT macro.
+   *
+   * Usage example:
+   *   ```RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeBaseInterface, base)```
+   *
+   * If you choose not to use the helper macro, then you can specialize the
+   * template yourself, but you must:
+   *
+   *   - Provide a template specialization of the get_from_node_like method that gets the interface
+   *     from any node-like that stores the interface, using the node-like's getter
+   *   - Designate the is_supported type as std::true_type using a using directive
+   *   - Provide any number of getter methods to be used to obtain the interface with the
+   *     NodeInterface object, noting that the getters of the storage class will apply to all
+   *     supported interfaces.
+   *     - The getter method names should not clash in name with any other interface getter
+   *       specializations if those other interfaces are meant to be aggregated in the same
+   *       NodeInterfaces object.
+   *
+   * \param[in] node Node-like object from which to get the node interfaces
+   */
+  template<typename NodeT>
+  NodeInterfaces(NodeT & node)  // NOLINT(runtime/explicit)
+  : NodeInterfacesSupportsT(node)
+  {}
+
+  // Create a NodeInterfaces object with no bound interfaces
+  NodeInterfaces()
+  : NodeInterfacesSupportsT()
+  {}
+
+  explicit NodeInterfaces(std::shared_ptr<InterfaceTs>... args)
+  : NodeInterfacesSupportsT(args ...)
+  {}
+};
+
+
+}  // namespace node_interfaces
+}  // namespace rclcpp
+
+#endif  // RCLCPP__NODE_INTERFACES__NODE_INTERFACES_HPP_

rclcpp/include/rclcpp/node_interfaces/node_logging_interface.hpp

@@ -19,6 +19,7 @@
 
 #include "rclcpp/logger.hpp"
 #include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
 #include "rclcpp/visibility_control.hpp"
 
 namespace rclcpp
@@ -37,14 +38,18 @@ public:
   ~NodeLoggingInterface() = default;
 
   /// Return the logger of the node.
-  /** \return The logger of the node. */
+  /**
+   * \return The logger of the node.
+   */
   RCLCPP_PUBLIC
   virtual
   rclcpp::Logger
   get_logger() const = 0;
 
   /// Return the logger name associated with the node.
-  /** \return The logger name associated with the node. */
+  /**
+   * \return The logger name associated with the node.
+   */
   RCLCPP_PUBLIC
   virtual
   const char *
@@ -54,4 +59,6 @@ public:
 }  // namespace node_interfaces
 }  // namespace rclcpp
 
+RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeLoggingInterface, logging)
+
 #endif  // RCLCPP__NODE_INTERFACES__NODE_LOGGING_INTERFACE_HPP_

rclcpp/include/rclcpp/node_interfaces/node_parameters.hpp

@@ -15,9 +15,10 @@
 #ifndef RCLCPP__NODE_INTERFACES__NODE_PARAMETERS_HPP_
 #define RCLCPP__NODE_INTERFACES__NODE_PARAMETERS_HPP_
 
+#include <list>
 #include <map>
 #include <memory>
-#include <list>
+#include <mutex>
 #include <string>
 #include <vector>
 
@@ -84,6 +85,16 @@ class NodeParameters : public NodeParametersInterface
 public:
   RCLCPP_SMART_PTR_ALIASES_ONLY(NodeParameters)
 
+  /// Constructor.
+  /**
+   * If using automatically_declare_parameters_from_overrides, overrides of
+   * get_parameter_overrides(), has_parameter(), declare_parameter() will not
+   * be respected.
+   * If this is an issue, pass false for
+   * automatically_declare_parameters_from_overrides and invoke
+   * perform_automatically_declare_parameters_from_overrides() manually after
+   * construction.
+   */
   RCLCPP_PUBLIC
   NodeParameters(
     const node_interfaces::NodeBaseInterface::SharedPtr node_base,
@@ -171,20 +182,48 @@ public:
   rcl_interfaces::msg::ListParametersResult
   list_parameters(const std::vector<std::string> & prefixes, uint64_t depth) const override;
 
+  RCLCPP_PUBLIC
+  RCUTILS_WARN_UNUSED
+  PreSetParametersCallbackHandle::SharedPtr
+  add_pre_set_parameters_callback(PreSetParametersCallbackType callback) override;
+
   RCLCPP_PUBLIC
   RCUTILS_WARN_UNUSED
   OnSetParametersCallbackHandle::SharedPtr
-  add_on_set_parameters_callback(OnParametersSetCallbackType callback) override;
+  add_on_set_parameters_callback(OnSetParametersCallbackType callback) override;
+
+  RCLCPP_PUBLIC
+  RCUTILS_WARN_UNUSED
+  PostSetParametersCallbackHandle::SharedPtr
+  add_post_set_parameters_callback(PostSetParametersCallbackType callback) override;
 
   RCLCPP_PUBLIC
   void
   remove_on_set_parameters_callback(const OnSetParametersCallbackHandle * const handler) override;
 
+  RCLCPP_PUBLIC
+  void
+  remove_post_set_parameters_callback(const PostSetParametersCallbackHandle * const handler)
+  override;
+
+  RCLCPP_PUBLIC
+  void
+  remove_pre_set_parameters_callback(const PreSetParametersCallbackHandle * const handler) override;
+
   RCLCPP_PUBLIC
   const std::map<std::string, rclcpp::ParameterValue> &
   get_parameter_overrides() const override;
 
-  using CallbacksContainerType = std::list<OnSetParametersCallbackHandle::WeakPtr>;
+  using PreSetCallbacksHandleContainer = std::list<PreSetParametersCallbackHandle::WeakPtr>;
+  using OnSetCallbacksHandleContainer = std::list<OnSetParametersCallbackHandle::WeakPtr>;
+  using PostSetCallbacksHandleContainer = std::list<PostSetParametersCallbackHandle::WeakPtr>;
+  using CallbacksContainerType [[deprecated("use OnSetCallbacksHandleContainer instead")]] =
+    OnSetCallbacksHandleContainer;
+
+protected:
+  RCLCPP_PUBLIC
+  void
+  perform_automatically_declare_parameters_from_overrides();
 
 private:
   RCLCPP_DISABLE_COPY(NodeParameters)
@@ -196,9 +235,11 @@ private:
   // declare_parameter, etc).  In those cases, this will be set to false.
   bool parameter_modification_enabled_{true};
 
-  OnParametersSetCallbackType on_parameters_set_callback_ = nullptr;
+  PreSetCallbacksHandleContainer pre_set_parameters_callback_container_;
 
-  CallbacksContainerType on_parameters_set_callback_container_;
+  OnSetCallbacksHandleContainer on_set_parameters_callback_container_;
+
+  PostSetCallbacksHandleContainer post_set_parameters_callback_container_;
 
   std::map<std::string, ParameterInfo> parameters_;
 

rclcpp/include/rclcpp/node_interfaces/node_parameters_interface.hpp

@@ -15,8 +15,8 @@
 #ifndef RCLCPP__NODE_INTERFACES__NODE_PARAMETERS_INTERFACE_HPP_
 #define RCLCPP__NODE_INTERFACES__NODE_PARAMETERS_INTERFACE_HPP_
 
+#include <functional>
 #include <map>
-#include <memory>
 #include <string>
 #include <vector>
 
@@ -25,6 +25,7 @@
 #include "rcl_interfaces/msg/set_parameters_result.hpp"
 
 #include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
 #include "rclcpp/parameter.hpp"
 #include "rclcpp/visibility_control.hpp"
 
@@ -33,16 +34,38 @@ namespace rclcpp
 namespace node_interfaces
 {
 
+struct PreSetParametersCallbackHandle
+{
+  RCLCPP_SMART_PTR_DEFINITIONS(PreSetParametersCallbackHandle)
+
+  using PreSetParametersCallbackType =
+    std::function<void (std::vector<rclcpp::Parameter> &)>;
+
+  PreSetParametersCallbackType callback;
+};
+
 struct OnSetParametersCallbackHandle
 {
   RCLCPP_SMART_PTR_DEFINITIONS(OnSetParametersCallbackHandle)
 
-  using OnParametersSetCallbackType =
+  using OnSetParametersCallbackType =
     std::function<
     rcl_interfaces::msg::SetParametersResult(
       const std::vector<rclcpp::Parameter> &)>;
+  using OnParametersSetCallbackType [[deprecated("use OnSetParametersCallbackType instead")]] =
+    OnSetParametersCallbackType;
 
-  OnParametersSetCallbackType callback;
+  OnSetParametersCallbackType callback;
+};
+
+struct PostSetParametersCallbackHandle
+{
+  RCLCPP_SMART_PTR_DEFINITIONS(PostSetParametersCallbackHandle)
+
+  using PostSetParametersCallbackType =
+    std::function<void (const std::vector<rclcpp::Parameter> &)>;
+
+  PostSetParametersCallbackType callback;
 };
 
 /// Pure virtual interface class for the NodeParameters part of the Node API.
@@ -185,16 +208,46 @@ public:
   rcl_interfaces::msg::ListParametersResult
   list_parameters(const std::vector<std::string> & prefixes, uint64_t depth) const = 0;
 
-  using OnParametersSetCallbackType = OnSetParametersCallbackHandle::OnParametersSetCallbackType;
+  using OnSetParametersCallbackType = OnSetParametersCallbackHandle::OnSetParametersCallbackType;
+  using PostSetParametersCallbackType =
+    PostSetParametersCallbackHandle::PostSetParametersCallbackType;
+  using PreSetParametersCallbackType = PreSetParametersCallbackHandle::PreSetParametersCallbackType;
 
-  /// Add a callback for when parameters are being set.
+  /// Add a callback that gets triggered before parameters are validated.
+  /**
+   * \sa rclcpp::Node::add_pre_set_parameters_callback
+   */
+  RCLCPP_PUBLIC
+  virtual
+  PreSetParametersCallbackHandle::SharedPtr
+  add_pre_set_parameters_callback(PreSetParametersCallbackType callback) = 0;
+
+  /// Add a callback to validate parameters before they are set.
   /**
    * \sa rclcpp::Node::add_on_set_parameters_callback
    */
   RCLCPP_PUBLIC
   virtual
   OnSetParametersCallbackHandle::SharedPtr
-  add_on_set_parameters_callback(OnParametersSetCallbackType callback) = 0;
+  add_on_set_parameters_callback(OnSetParametersCallbackType callback) = 0;
+
+  /// Add a callback that gets triggered after parameters are set successfully.
+  /**
+   * \sa rclcpp::Node::add_post_set_parameters_callback
+   */
+  RCLCPP_PUBLIC
+  virtual
+  PostSetParametersCallbackHandle::SharedPtr
+  add_post_set_parameters_callback(PostSetParametersCallbackType callback) = 0;
+
+  /// Remove a callback registered with `add_pre_set_parameters_callback`.
+  /**
+   * \sa rclcpp::Node::remove_pre_set_parameters_callback
+   */
+  RCLCPP_PUBLIC
+  virtual
+  void
+  remove_pre_set_parameters_callback(const PreSetParametersCallbackHandle * const handler) = 0;
 
   /// Remove a callback registered with `add_on_set_parameters_callback`.
   /**
@@ -205,6 +258,15 @@ public:
   void
   remove_on_set_parameters_callback(const OnSetParametersCallbackHandle * const handler) = 0;
 
+  /// Remove a callback registered with `add_post_set_parameters_callback`.
+  /**
+   * \sa rclcpp::Node::remove_post_set_parameters_callback
+   */
+  RCLCPP_PUBLIC
+  virtual
+  void
+  remove_post_set_parameters_callback(const PostSetParametersCallbackHandle * const handler) = 0;
+
   /// Return the initial parameter values used by the NodeParameters to override default values.
   RCLCPP_PUBLIC
   virtual
@@ -215,4 +277,6 @@ public:
 }  // namespace node_interfaces
 }  // namespace rclcpp
 
+RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeParametersInterface, parameters)
+
 #endif  // RCLCPP__NODE_INTERFACES__NODE_PARAMETERS_INTERFACE_HPP_

rclcpp/include/rclcpp/node_interfaces/node_services_interface.hpp

@@ -20,6 +20,7 @@
 #include "rclcpp/callback_group.hpp"
 #include "rclcpp/client.hpp"
 #include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
 #include "rclcpp/service.hpp"
 #include "rclcpp/visibility_control.hpp"
 
@@ -62,4 +63,6 @@ public:
 }  // namespace node_interfaces
 }  // namespace rclcpp
 
+RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeServicesInterface, services)
+
 #endif  // RCLCPP__NODE_INTERFACES__NODE_SERVICES_INTERFACE_HPP_

rclcpp/include/rclcpp/node_interfaces/node_time_source_interface.hpp

@@ -16,6 +16,7 @@
 #define RCLCPP__NODE_INTERFACES__NODE_TIME_SOURCE_INTERFACE_HPP_
 
 #include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
 #include "rclcpp/visibility_control.hpp"
 
 namespace rclcpp
@@ -37,4 +38,6 @@ public:
 }  // namespace node_interfaces
 }  // namespace rclcpp
 
+RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeTimeSourceInterface, time_source)
+
 #endif  // RCLCPP__NODE_INTERFACES__NODE_TIME_SOURCE_INTERFACE_HPP_

rclcpp/include/rclcpp/node_interfaces/node_timers_interface.hpp

@@ -17,6 +17,7 @@
 
 #include "rclcpp/callback_group.hpp"
 #include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
 #include "rclcpp/timer.hpp"
 #include "rclcpp/visibility_control.hpp"
 
@@ -47,4 +48,6 @@ public:
 }  // namespace node_interfaces
 }  // namespace rclcpp
 
+RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeTimersInterface, timers)
+
 #endif  // RCLCPP__NODE_INTERFACES__NODE_TIMERS_INTERFACE_HPP_

rclcpp/include/rclcpp/node_interfaces/node_topics_interface.hpp

@@ -15,8 +15,6 @@
 #ifndef RCLCPP__NODE_INTERFACES__NODE_TOPICS_INTERFACE_HPP_
 #define RCLCPP__NODE_INTERFACES__NODE_TOPICS_INTERFACE_HPP_
 
-#include <functional>
-#include <memory>
 #include <string>
 
 #include "rcl/publisher.h"
@@ -24,6 +22,7 @@
 
 #include "rclcpp/callback_group.hpp"
 #include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
 #include "rclcpp/node_interfaces/node_base_interface.hpp"
 #include "rclcpp/node_interfaces/node_timers_interface.hpp"
 #include "rclcpp/publisher.hpp"
@@ -97,4 +96,6 @@ public:
 }  // namespace node_interfaces
 }  // namespace rclcpp
 
+RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeTopicsInterface, topics)
+
 #endif  // RCLCPP__NODE_INTERFACES__NODE_TOPICS_INTERFACE_HPP_

rclcpp/include/rclcpp/node_interfaces/node_waitables_interface.hpp

@@ -17,6 +17,7 @@
 
 #include "rclcpp/callback_group.hpp"
 #include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
 #include "rclcpp/visibility_control.hpp"
 #include "rclcpp/waitable.hpp"
 
@@ -54,4 +55,6 @@ public:
 }  // namespace node_interfaces
 }  // namespace rclcpp
 
+RCLCPP_NODE_INTERFACE_HELPERS_SUPPORT(rclcpp::node_interfaces::NodeWaitablesInterface, waitables)
+
 #endif  // RCLCPP__NODE_INTERFACES__NODE_WAITABLES_INTERFACE_HPP_

rclcpp/include/rclcpp/node_options.hpp

@@ -19,6 +19,7 @@
 #include <string>
 #include <vector>
 
+#include "rcl/time.h"
 #include "rcl/node_options.h"
 #include "rclcpp/context.hpp"
 #include "rclcpp/contexts/default_context.hpp"
@@ -46,6 +47,7 @@ public:
    *   - enable_topic_statistics = false
    *   - start_parameter_services = true
    *   - start_parameter_event_publisher = true
+   *   - clock_type = RCL_ROS_TIME
    *   - clock_qos = rclcpp::ClockQoS()
    *   - use_clock_thread = true
    *   - rosout_qos = rclcpp::RosoutQoS()
@@ -246,6 +248,19 @@ public:
   NodeOptions &
   start_parameter_event_publisher(bool start_parameter_event_publisher);
 
+  /// Return a reference to the clock type.
+  RCLCPP_PUBLIC
+  const rcl_clock_type_t &
+  clock_type() const;
+
+  /// Set the clock type.
+  /**
+   * The clock type to be used by the node.
+   */
+  RCLCPP_PUBLIC
+  NodeOptions &
+  clock_type(const rcl_clock_type_t & clock_type);
+
   /// Return a reference to the clock QoS.
   RCLCPP_PUBLIC
   const rclcpp::QoS &
@@ -400,6 +415,8 @@ private:
 
   bool start_parameter_event_publisher_ {true};
 
+  rcl_clock_type_t clock_type_ {RCL_ROS_TIME};
+
   rclcpp::QoS clock_qos_ = rclcpp::ClockQoS();
 
   bool use_clock_thread_ {true};

rclcpp/include/rclcpp/parameter_client.hpp

@@ -39,6 +39,7 @@
 #include "rclcpp/node.hpp"
 #include "rclcpp/parameter.hpp"
 #include "rclcpp/parameter_map.hpp"
+#include "rclcpp/qos.hpp"
 #include "rclcpp/type_support_decl.hpp"
 #include "rclcpp/visibility_control.hpp"
 #include "rmw/rmw.h"
@@ -51,6 +52,37 @@ class AsyncParametersClient
 public:
   RCLCPP_SMART_PTR_DEFINITIONS(AsyncParametersClient)
 
+  /// Create an async parameters client.
+  /**
+   * \param[in] node_base_interface The node base interface of the corresponding node.
+   * \param[in] node_topics_interface Node topic base interface.
+   * \param[in] node_graph_interface The node graph interface of the corresponding node.
+   * \param[in] node_services_interface Node service interface.
+   * \param[in] remote_node_name Name of the remote node
+   * \param[in] qos_profile The rmw qos profile to use to subscribe
+   * \param[in] group (optional) The async parameter client will be added to this callback group.
+   * \deprecated use rclcpp::QoS instead of rmw_qos_profile_t
+   */
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
+  RCLCPP_PUBLIC
+  AsyncParametersClient(
+    const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_base_interface,
+    const rclcpp::node_interfaces::NodeTopicsInterface::SharedPtr node_topics_interface,
+    const rclcpp::node_interfaces::NodeGraphInterface::SharedPtr node_graph_interface,
+    const rclcpp::node_interfaces::NodeServicesInterface::SharedPtr node_services_interface,
+    const std::string & remote_node_name,
+    const rmw_qos_profile_t & qos_profile,
+    rclcpp::CallbackGroup::SharedPtr group = nullptr)
+  : AsyncParametersClient(
+      node_base_interface,
+      node_topics_interface,
+      node_graph_interface,
+      node_services_interface,
+      remote_node_name,
+      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(qos_profile)),
+      group)
+  {}
+
   /// Create an async parameters client.
   /**
    * \param[in] node_base_interface The node base interface of the corresponding node.
@@ -58,7 +90,7 @@ public:
    * \param[in] node_graph_interface The node graph interface of the corresponding node.
    * \param[in] node_services_interface Node service interface.
    * \param[in] remote_node_name (optional) name of the remote node
-   * \param[in] qos_profile (optional) The rmw qos profile to use to subscribe
+   * \param[in] qos_profile (optional) The qos profile to use to subscribe
    * \param[in] group (optional) The async parameter client will be added to this callback group.
    */
   RCLCPP_PUBLIC
@@ -68,21 +100,45 @@ public:
     const rclcpp::node_interfaces::NodeGraphInterface::SharedPtr node_graph_interface,
     const rclcpp::node_interfaces::NodeServicesInterface::SharedPtr node_services_interface,
     const std::string & remote_node_name = "",
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_parameters,
+    const rclcpp::QoS & qos_profile = rclcpp::ParametersQoS(),
     rclcpp::CallbackGroup::SharedPtr group = nullptr);
 
   /// Constructor
   /**
-   * \param[in] node The async paramters client will be added to this node.
+   * \param[in] node The async parameters client will be added to this node.
+   * \param[in] remote_node_name name of the remote node
+   * \param[in] qos_profile The rmw qos profile to use to subscribe
+   * \param[in] group (optional) The async parameter client will be added to this callback group.
+   * \deprecated use rclcpp::QoS instead of rmw_qos_profile_t
+   */
+  template<typename NodeT>
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
+  AsyncParametersClient(
+    const std::shared_ptr<NodeT> node,
+    const std::string & remote_node_name,
+    const rmw_qos_profile_t & qos_profile,
+    rclcpp::CallbackGroup::SharedPtr group = nullptr)
+  : AsyncParametersClient(
+      node->get_node_base_interface(),
+      node->get_node_topics_interface(),
+      node->get_node_graph_interface(),
+      node->get_node_services_interface(),
+      remote_node_name,
+      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(qos_profile)),
+      group)
+  {}
+
+  /**
+   * \param[in] node The async parameters client will be added to this node.
    * \param[in] remote_node_name (optional) name of the remote node
-   * \param[in] qos_profile (optional) The rmw qos profile to use to subscribe
+   * \param[in] qos_profile (optional) The qos profile to use to subscribe
    * \param[in] group (optional) The async parameter client will be added to this callback group.
    */
   template<typename NodeT>
   explicit AsyncParametersClient(
     const std::shared_ptr<NodeT> node,
     const std::string & remote_node_name = "",
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_parameters,
+    const rclcpp::QoS & qos_profile = rclcpp::ParametersQoS(),
     rclcpp::CallbackGroup::SharedPtr group = nullptr)
   : AsyncParametersClient(
       node->get_node_base_interface(),
@@ -96,16 +152,40 @@ public:
 
   /// Constructor
   /**
-   * \param[in] node The  async paramters client will be added to this node.
+   * \param[in] node The async parameters client will be added to this node.
+   * \param[in] remote_node_name Name of the remote node
+   * \param[in] qos_profile The rmw qos profile to use to subscribe
+   * \param[in] group (optional) The async parameter client will be added to this callback group.
+   * \deprecated use rclcpp::QoS instead of rmw_qos_profile_t
+   */
+  template<typename NodeT>
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
+  AsyncParametersClient(
+    NodeT * node,
+    const std::string & remote_node_name,
+    const rmw_qos_profile_t & qos_profile,
+    rclcpp::CallbackGroup::SharedPtr group = nullptr)
+  : AsyncParametersClient(
+      node->get_node_base_interface(),
+      node->get_node_topics_interface(),
+      node->get_node_graph_interface(),
+      node->get_node_services_interface(),
+      remote_node_name,
+      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(qos_profile)),
+      group)
+  {}
+
+  /**
+   * \param[in] node The async parameters client will be added to this node.
    * \param[in] remote_node_name (optional) name of the remote node
-   * \param[in] qos_profile (optional) The rmw qos profile to use to subscribe
+   * \param[in] qos_profile (optional) The qos profile to use to subscribe
    * \param[in] group (optional) The async parameter client will be added to this callback group.
    */
   template<typename NodeT>
   explicit AsyncParametersClient(
     NodeT * node,
     const std::string & remote_node_name = "",
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_parameters,
+    const rclcpp::QoS & qos_profile = rclcpp::ParametersQoS(),
     rclcpp::CallbackGroup::SharedPtr group = nullptr)
   : AsyncParametersClient(
       node->get_node_base_interface(),
@@ -185,6 +265,9 @@ public:
   /**
    * This function filters the parameters to be set based on the node name.
    *
+   * If two duplicate keys exist in node names belongs to one FQN, there is no guarantee
+   * which one could be set.
+   *
    * \param parameter_map named parameters to be loaded
    * \return the future of the set_parameter service used to load the parameters
    * \throw InvalidParametersException if there is no parameter to set
@@ -208,9 +291,7 @@ public:
   typename rclcpp::Subscription<rcl_interfaces::msg::ParameterEvent>::SharedPtr
   on_parameter_event(
     CallbackT && callback,
-    const rclcpp::QoS & qos = (
-      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(rmw_qos_profile_parameter_events))
-    ),
+    const rclcpp::QoS & qos = rclcpp::ParameterEventsQoS(),
     const rclcpp::SubscriptionOptionsWithAllocator<AllocatorT> & options = (
       rclcpp::SubscriptionOptionsWithAllocator<AllocatorT>()
   ))
@@ -235,9 +316,7 @@ public:
   on_parameter_event(
     NodeT && node,
     CallbackT && callback,
-    const rclcpp::QoS & qos = (
-      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(rmw_qos_profile_parameter_events))
-    ),
+    const rclcpp::QoS & qos = rclcpp::ParameterEventsQoS(),
     const rclcpp::SubscriptionOptionsWithAllocator<AllocatorT> & options = (
       rclcpp::SubscriptionOptionsWithAllocator<AllocatorT>()
   ))
@@ -304,11 +383,24 @@ class SyncParametersClient
 public:
   RCLCPP_SMART_PTR_DEFINITIONS(SyncParametersClient)
 
+  template<typename NodeT>
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
+  SyncParametersClient(
+    std::shared_ptr<NodeT> node,
+    const std::string & remote_node_name,
+    const rmw_qos_profile_t & qos_profile)
+  : SyncParametersClient(
+      std::make_shared<rclcpp::executors::SingleThreadedExecutor>(),
+      node,
+      remote_node_name,
+      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(qos_profile)))
+  {}
+
   template<typename NodeT>
   explicit SyncParametersClient(
     std::shared_ptr<NodeT> node,
     const std::string & remote_node_name = "",
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_parameters)
+    const rclcpp::QoS & qos_profile = rclcpp::ParametersQoS())
   : SyncParametersClient(
       std::make_shared<rclcpp::executors::SingleThreadedExecutor>(),
       node,
@@ -316,12 +408,29 @@ public:
       qos_profile)
   {}
 
+  template<typename NodeT>
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
+  SyncParametersClient(
+    rclcpp::Executor::SharedPtr executor,
+    std::shared_ptr<NodeT> node,
+    const std::string & remote_node_name,
+    const rmw_qos_profile_t & qos_profile)
+  : SyncParametersClient(
+      executor,
+      node->get_node_base_interface(),
+      node->get_node_topics_interface(),
+      node->get_node_graph_interface(),
+      node->get_node_services_interface(),
+      remote_node_name,
+      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(qos_profile)))
+  {}
+
   template<typename NodeT>
   SyncParametersClient(
     rclcpp::Executor::SharedPtr executor,
     std::shared_ptr<NodeT> node,
     const std::string & remote_node_name = "",
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_parameters)
+    const rclcpp::QoS & qos_profile = rclcpp::ParametersQoS())
   : SyncParametersClient(
       executor,
       node->get_node_base_interface(),
@@ -332,11 +441,24 @@ public:
       qos_profile)
   {}
 
+  template<typename NodeT>
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
+  SyncParametersClient(
+    NodeT * node,
+    const std::string & remote_node_name,
+    const rmw_qos_profile_t & qos_profile)
+  : SyncParametersClient(
+      std::make_shared<rclcpp::executors::SingleThreadedExecutor>(),
+      node,
+      remote_node_name,
+      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(qos_profile)))
+  {}
+
   template<typename NodeT>
   explicit SyncParametersClient(
     NodeT * node,
     const std::string & remote_node_name = "",
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_parameters)
+    const rclcpp::QoS & qos_profile = rclcpp::ParametersQoS())
   : SyncParametersClient(
       std::make_shared<rclcpp::executors::SingleThreadedExecutor>(),
       node,
@@ -344,12 +466,29 @@ public:
       qos_profile)
   {}
 
+  template<typename NodeT>
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
+  SyncParametersClient(
+    rclcpp::Executor::SharedPtr executor,
+    NodeT * node,
+    const std::string & remote_node_name,
+    const rmw_qos_profile_t & qos_profile)
+  : SyncParametersClient(
+      executor,
+      node->get_node_base_interface(),
+      node->get_node_topics_interface(),
+      node->get_node_graph_interface(),
+      node->get_node_services_interface(),
+      remote_node_name,
+      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(qos_profile)))
+  {}
+
   template<typename NodeT>
   SyncParametersClient(
     rclcpp::Executor::SharedPtr executor,
     NodeT * node,
     const std::string & remote_node_name = "",
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_parameters)
+    const rclcpp::QoS & qos_profile = rclcpp::ParametersQoS())
   : SyncParametersClient(
       executor,
       node->get_node_base_interface(),
@@ -360,6 +499,28 @@ public:
       qos_profile)
   {}
 
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
+  RCLCPP_PUBLIC
+  SyncParametersClient(
+    rclcpp::Executor::SharedPtr executor,
+    const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_base_interface,
+    const rclcpp::node_interfaces::NodeTopicsInterface::SharedPtr node_topics_interface,
+    const rclcpp::node_interfaces::NodeGraphInterface::SharedPtr node_graph_interface,
+    const rclcpp::node_interfaces::NodeServicesInterface::SharedPtr node_services_interface,
+    const std::string & remote_node_name,
+    const rmw_qos_profile_t & qos_profile)
+  : executor_(executor), node_base_interface_(node_base_interface)
+  {
+    async_parameters_client_ =
+      std::make_shared<AsyncParametersClient>(
+      node_base_interface,
+      node_topics_interface,
+      node_graph_interface,
+      node_services_interface,
+      remote_node_name,
+      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(qos_profile)));
+  }
+
   RCLCPP_PUBLIC
   SyncParametersClient(
     rclcpp::Executor::SharedPtr executor,
@@ -368,7 +529,7 @@ public:
     const rclcpp::node_interfaces::NodeGraphInterface::SharedPtr node_graph_interface,
     const rclcpp::node_interfaces::NodeServicesInterface::SharedPtr node_services_interface,
     const std::string & remote_node_name = "",
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_parameters)
+    const rclcpp::QoS & qos_profile = rclcpp::ParametersQoS())
   : executor_(executor), node_base_interface_(node_base_interface)
   {
     async_parameters_client_ =

rclcpp/include/rclcpp/parameter_event_handler.hpp

@@ -86,6 +86,9 @@ struct ParameterEventCallbackHandle
  * the ROS node supplied in the ParameterEventHandler constructor.
  * The callback, a lambda function in this case, simply prints out the value of the parameter.
  *
+ * Note: the object returned from add_parameter_callback must be captured or the callback will
+ * be immediately unregistered.
+ *
  * You may also monitor for changes to parameters in other nodes by supplying the node
  * name to add_parameter_callback:
  *
@@ -103,8 +106,8 @@ struct ParameterEventCallbackHandle
  * In this case, the callback will be invoked whenever "some_remote_param_name" changes
  * on remote node "some_remote_node_name".
  *
- * To remove a parameter callback, call remove_parameter_callback, passing the handle returned
- * from add_parameter_callback:
+ * To remove a parameter callback, reset the callback handle smart pointer or call
+ * remove_parameter_callback, passing the handle returned from add_parameter_callback:
  *
  *   param_handler->remove_parameter_callback(handle2);
  *
@@ -152,9 +155,12 @@ struct ParameterEventCallbackHandle
  * For both parameter callbacks and parameter event callbacks, when multiple callbacks are added,
  * the callbacks are invoked last-in, first-called order (LIFO).
  *
- * To remove a parameter event callback, use:
+ * Note: the callback handle returned from add_parameter_event_callback must be captured or
+ * the callback will immediately be unregistered.
  *
- *   param_handler->remove_event_parameter_callback(handle);
+ * To remove a parameter event callback, reset the callback smart pointer or use:
+ *
+ *   param_handler->remove_event_parameter_callback(handle3);
  */
 class ParameterEventHandler
 {
@@ -189,10 +195,14 @@ public:
   /**
    * This function may be called multiple times to set multiple parameter event callbacks.
    *
+   * Note: if the returned callback handle smart pointer is not captured, the callback is
+   * immediatedly unregistered. A compiler warning should be generated to warn of this.
+   *
    * \param[in] callback Function callback to be invoked on parameter updates.
    * \returns A handle used to refer to the callback.
    */
   RCLCPP_PUBLIC
+  RCUTILS_WARN_UNUSED
   ParameterEventCallbackHandle::SharedPtr
   add_parameter_event_callback(
     ParameterEventCallbackType callback);
@@ -212,12 +222,17 @@ public:
   /**
    * If a node_name is not provided, defaults to the current node.
    *
+   * Note: if the returned callback handle smart pointer is not captured, the callback
+   * is immediately unregistered. A compiler warning should be generated to warn
+   * of this.
+   *
    * \param[in] parameter_name Name of parameter to monitor.
    * \param[in] callback Function callback to be invoked upon parameter update.
    * \param[in] node_name Name of node which hosts the parameter.
    * \returns A handle used to refer to the callback.
    */
   RCLCPP_PUBLIC
+  RCUTILS_WARN_UNUSED
   ParameterCallbackHandle::SharedPtr
   add_parameter_callback(
     const std::string & parameter_name,
@@ -268,6 +283,7 @@ public:
    * \param[in] parameter_name Name of parameter.
    * \param[in] node_name Name of node which hosts the parameter.
    * \returns The resultant rclcpp::Parameter from the event.
+   * \throws std::runtime_error if input node name doesn't match the node name in parameter event.
    */
   RCLCPP_PUBLIC
   static rclcpp::Parameter

rclcpp/include/rclcpp/parameter_map.hpp

@@ -35,11 +35,13 @@ using ParameterMap = std::unordered_map<std::string, std::vector<Parameter>>;
 
 /// Convert parameters from rcl_yaml_param_parser into C++ class instances.
 /// \param[in] c_params C structures containing parameters for multiple nodes.
+/// \param[in] node_fqn a Fully Qualified Name of node, default value is nullptr.
+///   If it's not nullptr, return the relative node parameters belonging to this node_fqn.
 /// \returns a map where the keys are fully qualified node names and values a list of parameters.
 /// \throws InvalidParametersException if the `rcl_params_t` is inconsistent or invalid.
 RCLCPP_PUBLIC
 ParameterMap
-parameter_map_from(const rcl_params_t * const c_params);
+parameter_map_from(const rcl_params_t * const c_params, const char * node_fqn = nullptr);
 
 /// Convert parameter value from rcl_yaml_param_parser into a C++ class instance.
 /// \param[in] c_value C structure containing a value of a parameter.
@@ -51,11 +53,20 @@ parameter_value_from(const rcl_variant_t * const c_value);
 
 /// Get the ParameterMap from a yaml file.
 /// \param[in] yaml_filename full name of the yaml file.
+/// \param[in] node_fqn a Fully Qualified Name of node, default value is nullptr.
 /// \returns an instance of a parameter map
 /// \throws from rcl error of rcl_parse_yaml_file()
 RCLCPP_PUBLIC
 ParameterMap
-parameter_map_from_yaml_file(const std::string & yaml_filename);
+parameter_map_from_yaml_file(const std::string & yaml_filename, const char * node_fqn = nullptr);
+
+/// Get the Parameters from ParameterMap.
+/// \param[in] parameter_map a parameter map.
+/// \param[in] node_fqn a Fully Qualified Name of node, default value is nullptr.
+/// \returns a list of a parameter
+RCLCPP_PUBLIC
+std::vector<Parameter>
+parameters_from_map(const ParameterMap & parameter_map, const char * node_fqn = nullptr);
 
 }  // namespace rclcpp
 

rclcpp/include/rclcpp/parameter_service.hpp

@@ -28,6 +28,7 @@
 #include "rclcpp/macros.hpp"
 #include "rclcpp/node.hpp"
 #include "rclcpp/parameter.hpp"
+#include "rclcpp/qos.hpp"
 #include "rclcpp/visibility_control.hpp"
 #include "rmw/rmw.h"
 
@@ -39,12 +40,26 @@ class ParameterService
 public:
   RCLCPP_SMART_PTR_DEFINITIONS(ParameterService)
 
+  [[deprecated("use rclcpp::QoS instead of rmw_qos_profile_t")]]
   RCLCPP_PUBLIC
-  explicit ParameterService(
+  ParameterService(
     const std::shared_ptr<node_interfaces::NodeBaseInterface> node_base,
     const std::shared_ptr<node_interfaces::NodeServicesInterface> node_services,
     rclcpp::node_interfaces::NodeParametersInterface * node_params,
-    const rmw_qos_profile_t & qos_profile = rmw_qos_profile_parameters);
+    const rmw_qos_profile_t & qos_profile)
+  : ParameterService(
+      node_base,
+      node_services,
+      node_params,
+      rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(qos_profile)))
+  {}
+
+  RCLCPP_PUBLIC
+  ParameterService(
+    const std::shared_ptr<node_interfaces::NodeBaseInterface> node_base,
+    const std::shared_ptr<node_interfaces::NodeServicesInterface> node_services,
+    rclcpp::node_interfaces::NodeParametersInterface * node_params,
+    const rclcpp::QoS & qos_profile = rclcpp::ParametersQoS());
 
 private:
   rclcpp::Service<rcl_interfaces::srv::GetParameters>::SharedPtr get_parameters_service_;

rclcpp/include/rclcpp/publisher.hpp

@@ -131,40 +131,16 @@ public:
       node_base,
       topic,
       rclcpp::get_message_type_support_handle<MessageT>(),
-      options.template to_rcl_publisher_options<MessageT>(qos)),
+      options.template to_rcl_publisher_options<MessageT>(qos),
+      // NOTE(methylDragon): Passing these args separately is necessary for event binding
+      options.event_callbacks,
+      options.use_default_callbacks),
     options_(options),
     published_type_allocator_(*options.get_allocator()),
     ros_message_type_allocator_(*options.get_allocator())
   {
     allocator::set_allocator_for_deleter(&published_type_deleter_, &published_type_allocator_);
     allocator::set_allocator_for_deleter(&ros_message_type_deleter_, &ros_message_type_allocator_);
-
-    if (options_.event_callbacks.deadline_callback) {
-      this->add_event_handler(
-        options_.event_callbacks.deadline_callback,
-        RCL_PUBLISHER_OFFERED_DEADLINE_MISSED);
-    }
-    if (options_.event_callbacks.liveliness_callback) {
-      this->add_event_handler(
-        options_.event_callbacks.liveliness_callback,
-        RCL_PUBLISHER_LIVELINESS_LOST);
-    }
-    if (options_.event_callbacks.incompatible_qos_callback) {
-      this->add_event_handler(
-        options_.event_callbacks.incompatible_qos_callback,
-        RCL_PUBLISHER_OFFERED_INCOMPATIBLE_QOS);
-    } else if (options_.use_default_callbacks) {
-      // Register default callback when not specified
-      try {
-        this->add_event_handler(
-          [this](QOSOfferedIncompatibleQoSInfo & info) {
-            this->default_incompatible_qos_callback(info);
-          },
-          RCL_PUBLISHER_OFFERED_INCOMPATIBLE_QOS);
-      } catch (UnsupportedEventTypeException & /*exc*/) {
-        // pass
-      }
-    }
     // Setup continues in the post construction method, post_init_setup().
   }
 

rclcpp/include/rclcpp/publisher_base.hpp

@@ -78,11 +78,18 @@ public:
     rclcpp::node_interfaces::NodeBaseInterface * node_base,
     const std::string & topic,
     const rosidl_message_type_support_t & type_support,
-    const rcl_publisher_options_t & publisher_options);
+    const rcl_publisher_options_t & publisher_options,
+    const PublisherEventCallbacks & event_callbacks,
+    bool use_default_callbacks);
 
   RCLCPP_PUBLIC
   virtual ~PublisherBase();
 
+  /// Add event handlers for passed in event_callbacks.
+  RCLCPP_PUBLIC
+  void
+  bind_event_callbacks(const PublisherEventCallbacks & event_callbacks, bool use_default_callbacks);
+
   /// Get the topic that this publisher publishes on.
   /** \return The topic name. */
   RCLCPP_PUBLIC
@@ -348,6 +355,8 @@ protected:
   rmw_gid_t rmw_gid_;
 
   const rosidl_message_type_support_t type_support_;
+
+  const PublisherEventCallbacks event_callbacks_;
 };
 
 }  // namespace rclcpp

rclcpp/include/rclcpp/publisher_options.hpp

@@ -72,7 +72,7 @@ struct PublisherOptionsWithAllocator : public PublisherOptionsBase
   /// Optional custom allocator.
   std::shared_ptr<Allocator> allocator = nullptr;
 
-  PublisherOptionsWithAllocator<Allocator>() {}
+  PublisherOptionsWithAllocator() {}
 
   /// Constructor using base class as input.
   explicit PublisherOptionsWithAllocator(const PublisherOptionsBase & publisher_options_base)

rclcpp/include/rclcpp/qos.hpp

@@ -44,6 +44,7 @@ enum class ReliabilityPolicy
   BestEffort = RMW_QOS_POLICY_RELIABILITY_BEST_EFFORT,
   Reliable = RMW_QOS_POLICY_RELIABILITY_RELIABLE,
   SystemDefault = RMW_QOS_POLICY_RELIABILITY_SYSTEM_DEFAULT,
+  BestAvailable = RMW_QOS_POLICY_RELIABILITY_BEST_AVAILABLE,
   Unknown = RMW_QOS_POLICY_RELIABILITY_UNKNOWN,
 };
 
@@ -52,6 +53,7 @@ enum class DurabilityPolicy
   Volatile = RMW_QOS_POLICY_DURABILITY_VOLATILE,
   TransientLocal = RMW_QOS_POLICY_DURABILITY_TRANSIENT_LOCAL,
   SystemDefault = RMW_QOS_POLICY_DURABILITY_SYSTEM_DEFAULT,
+  BestAvailable = RMW_QOS_POLICY_DURABILITY_BEST_AVAILABLE,
   Unknown = RMW_QOS_POLICY_DURABILITY_UNKNOWN,
 };
 
@@ -60,6 +62,7 @@ enum class LivelinessPolicy
   Automatic = RMW_QOS_POLICY_LIVELINESS_AUTOMATIC,
   ManualByTopic = RMW_QOS_POLICY_LIVELINESS_MANUAL_BY_TOPIC,
   SystemDefault = RMW_QOS_POLICY_LIVELINESS_SYSTEM_DEFAULT,
+  BestAvailable = RMW_QOS_POLICY_LIVELINESS_BEST_AVAILABLE,
   Unknown = RMW_QOS_POLICY_LIVELINESS_UNKNOWN,
 };
 
@@ -77,7 +80,9 @@ struct RCLCPP_PUBLIC QoSInitialization
   size_t depth;
 
   /// Constructor which takes both a history policy and a depth (even if it would be unused).
-  QoSInitialization(rmw_qos_history_policy_t history_policy_arg, size_t depth_arg);
+  QoSInitialization(
+    rmw_qos_history_policy_t history_policy_arg, size_t depth_arg,
+    bool print_depth_warning = true);
 
   /// Create a QoSInitialization from an existing rmw_qos_profile_t, using its history and depth.
   static
@@ -94,7 +99,7 @@ struct RCLCPP_PUBLIC KeepAll : public rclcpp::QoSInitialization
 /// Use to initialize the QoS with the keep_last history setting and the given depth.
 struct RCLCPP_PUBLIC KeepLast : public rclcpp::QoSInitialization
 {
-  explicit KeepLast(size_t depth);
+  explicit KeepLast(size_t depth, bool print_depth_warning = true);
 };
 
 /// Encapsulation of Quality of Service settings.
@@ -180,6 +185,10 @@ public:
   QoS &
   best_effort();
 
+  /// Set the reliability setting to best available.
+  QoS &
+  reliability_best_available();
+
   /// Set the durability setting.
   QoS &
   durability(rmw_qos_durability_policy_t durability);
@@ -199,6 +208,10 @@ public:
   QoS &
   transient_local();
 
+  /// Set the durability setting to best available.
+  QoS &
+  durability_best_available();
+
   /// Set the deadline setting.
   QoS &
   deadline(rmw_time_t deadline);
@@ -488,6 +501,36 @@ public:
   ));
 };
 
+/**
+ * Best available QoS class
+ *
+ * Match majority of endpoints currently available while maintaining the highest level of service.
+ * Policies are chosen at the time of creating a subscription or publisher.
+ * The middleware is not expected to update policies after creating a subscription or publisher,
+ * even if one or more policies are incompatible with newly discovered endpoints.
+ * Therefore, this profile should be used with care since non-deterministic behavior can occur due
+ * to races with discovery.
+ *
+ *    - History: Keep last,
+ *    - Depth: 10,
+ *    - Reliability: Best available,
+ *    - Durability: Best available,
+ *    - Deadline: Best available,
+ *    - Lifespan: Default,
+ *    - Liveliness: Best available,
+ *    - Liveliness lease duration: Best available,
+ *    - avoid ros namespace conventions: false
+ */
+class RCLCPP_PUBLIC BestAvailableQoS : public QoS
+{
+public:
+  explicit
+  BestAvailableQoS(
+    const QoSInitialization & qos_initialization = (
+      QoSInitialization::from_rmw(rmw_qos_profile_best_available)
+  ));
+};
+
 }  // namespace rclcpp
 
 #endif  // RCLCPP__QOS_HPP_

rclcpp/include/rclcpp/qos_event.hpp

@@ -185,7 +185,7 @@ public:
     // This two-step setting, prevents a gap where the old std::function has
     // been replaced but the middleware hasn't been told about the new one yet.
     set_on_new_event_callback(
-      rclcpp::detail::cpp_callback_trampoline<const void *, size_t>,
+      rclcpp::detail::cpp_callback_trampoline<decltype(new_callback), const void *, size_t>,
       static_cast<const void *>(&new_callback));
 
     // Store the std::function to keep it in scope, also overwrites the existing one.
@@ -193,7 +193,8 @@ public:
 
     // Set it again, now using the permanent storage.
     set_on_new_event_callback(
-      rclcpp::detail::cpp_callback_trampoline<const void *, size_t>,
+      rclcpp::detail::cpp_callback_trampoline<
+        decltype(on_new_event_callback_), const void *, size_t>,
       static_cast<const void *>(&on_new_event_callback_));
   }
 
@@ -213,10 +214,11 @@ protected:
   void
   set_on_new_event_callback(rcl_event_callback_t callback, const void * user_data);
 
-  rcl_event_t event_handle_;
-  size_t wait_set_event_index_;
   std::recursive_mutex callback_mutex_;
   std::function<void(size_t)> on_new_event_callback_{nullptr};
+
+  rcl_event_t event_handle_;
+  size_t wait_set_event_index_;
 };
 
 template<typename EventCallbackT, typename ParentHandleT>

rclcpp/include/rclcpp/service.hpp

@@ -55,7 +55,7 @@ public:
   explicit ServiceBase(std::shared_ptr<rcl_node_t> node_handle);
 
   RCLCPP_PUBLIC
-  virtual ~ServiceBase();
+  virtual ~ServiceBase() = default;
 
   /// Return the name of the service.
   /** \return The name of the service. */
@@ -222,7 +222,7 @@ public:
     // This two-step setting, prevents a gap where the old std::function has
     // been replaced but the middleware hasn't been told about the new one yet.
     set_on_new_request_callback(
-      rclcpp::detail::cpp_callback_trampoline<const void *, size_t>,
+      rclcpp::detail::cpp_callback_trampoline<decltype(new_callback), const void *, size_t>,
       static_cast<const void *>(&new_callback));
 
     // Store the std::function to keep it in scope, also overwrites the existing one.
@@ -230,7 +230,8 @@ public:
 
     // Set it again, now using the permanent storage.
     set_on_new_request_callback(
-      rclcpp::detail::cpp_callback_trampoline<const void *, size_t>,
+      rclcpp::detail::cpp_callback_trampoline<
+        decltype(on_new_request_callback_), const void *, size_t>,
       static_cast<const void *>(&on_new_request_callback_));
   }
 

rclcpp/include/rclcpp/subscription.hpp

@@ -140,44 +140,15 @@ public:
       node_base,
       type_support_handle,
       topic_name,
-      options.template to_rcl_subscription_options<ROSMessageType>(qos),
+      options.to_rcl_subscription_options(qos),
+      // NOTE(methylDragon): Passing these args separately is necessary for event binding
+      options.event_callbacks,
+      options.use_default_callbacks,
       callback.is_serialized_message_callback()),
     any_callback_(callback),
     options_(options),
     message_memory_strategy_(message_memory_strategy)
   {
-    if (options_.event_callbacks.deadline_callback) {
-      this->add_event_handler(
-        options_.event_callbacks.deadline_callback,
-        RCL_SUBSCRIPTION_REQUESTED_DEADLINE_MISSED);
-    }
-    if (options_.event_callbacks.liveliness_callback) {
-      this->add_event_handler(
-        options_.event_callbacks.liveliness_callback,
-        RCL_SUBSCRIPTION_LIVELINESS_CHANGED);
-    }
-    if (options_.event_callbacks.incompatible_qos_callback) {
-      this->add_event_handler(
-        options_.event_callbacks.incompatible_qos_callback,
-        RCL_SUBSCRIPTION_REQUESTED_INCOMPATIBLE_QOS);
-    } else if (options_.use_default_callbacks) {
-      // Register default callback when not specified
-      try {
-        this->add_event_handler(
-          [this](QOSRequestedIncompatibleQoSInfo & info) {
-            this->default_incompatible_qos_callback(info);
-          },
-          RCL_SUBSCRIPTION_REQUESTED_INCOMPATIBLE_QOS);
-      } catch (UnsupportedEventTypeException & /*exc*/) {
-        // pass
-      }
-    }
-    if (options_.event_callbacks.message_lost_callback) {
-      this->add_event_handler(
-        options_.event_callbacks.message_lost_callback,
-        RCL_SUBSCRIPTION_MESSAGE_LOST);
-    }
-
     // Setup intra process publishing if requested.
     if (rclcpp::detail::resolve_use_intra_process(options_, *node_base)) {
       using rclcpp::detail::resolve_intra_process_buffer_type;
@@ -363,11 +334,31 @@ public:
     void * loaned_message,
     const rclcpp::MessageInfo & message_info) override
   {
+    if (matches_any_intra_process_publishers(&message_info.get_rmw_message_info().publisher_gid)) {
+      // In this case, the message will be delivered via intra process and
+      // we should ignore this copy of the message.
+      return;
+    }
+
     auto typed_message = static_cast<ROSMessageType *>(loaned_message);
     // message is loaned, so we have to make sure that the deleter does not deallocate the message
     auto sptr = std::shared_ptr<ROSMessageType>(
       typed_message, [](ROSMessageType * msg) {(void) msg;});
+
+    std::chrono::time_point<std::chrono::system_clock> now;
+    if (subscription_topic_statistics_) {
+      // get current time before executing callback to
+      // exclude callback duration from topic statistics result.
+      now = std::chrono::system_clock::now();
+    }
+
     any_callback_.dispatch(sptr, message_info);
+
+    if (subscription_topic_statistics_) {
+      const auto nanos = std::chrono::time_point_cast<std::chrono::nanoseconds>(now);
+      const auto time = rclcpp::Time(nanos.time_since_epoch().count());
+      subscription_topic_statistics_->handle_message(*typed_message, time);
+    }
   }
 
   /// Return the borrowed message.

rclcpp/include/rclcpp/subscription_base.hpp

@@ -84,12 +84,20 @@ public:
     const rosidl_message_type_support_t & type_support_handle,
     const std::string & topic_name,
     const rcl_subscription_options_t & subscription_options,
+    const SubscriptionEventCallbacks & event_callbacks,
+    bool use_default_callbacks,
     bool is_serialized = false);
 
   /// Destructor.
   RCLCPP_PUBLIC
   virtual ~SubscriptionBase();
 
+  /// Add event handlers for passed in event_callbacks.
+  RCLCPP_PUBLIC
+  void
+  bind_event_callbacks(
+    const SubscriptionEventCallbacks & event_callbacks, bool use_default_callbacks);
+
   /// Get the topic that this subscription is subscribed on.
   RCLCPP_PUBLIC
   const char *
@@ -348,7 +356,7 @@ public:
     // This two-step setting, prevents a gap where the old std::function has
     // been replaced but the middleware hasn't been told about the new one yet.
     set_on_new_message_callback(
-      rclcpp::detail::cpp_callback_trampoline<const void *, size_t>,
+      rclcpp::detail::cpp_callback_trampoline<decltype(new_callback), const void *, size_t>,
       static_cast<const void *>(&new_callback));
 
     // Store the std::function to keep it in scope, also overwrites the existing one.
@@ -356,7 +364,8 @@ public:
 
     // Set it again, now using the permanent storage.
     set_on_new_message_callback(
-      rclcpp::detail::cpp_callback_trampoline<const void *, size_t>,
+      rclcpp::detail::cpp_callback_trampoline<
+        decltype(on_new_message_callback_), const void *, size_t>,
       static_cast<const void *>(&on_new_message_callback_));
   }
 
@@ -569,6 +578,8 @@ protected:
   uint64_t intra_process_subscription_id_;
   std::shared_ptr<rclcpp::experimental::SubscriptionIntraProcessBase> subscription_intra_process_;
 
+  const SubscriptionEventCallbacks event_callbacks_;
+
 private:
   RCLCPP_DISABLE_COPY(SubscriptionBase)
 

rclcpp/include/rclcpp/subscription_options.hpp

@@ -97,7 +97,7 @@ struct SubscriptionOptionsWithAllocator : public SubscriptionOptionsBase
   /// Optional custom allocator.
   std::shared_ptr<Allocator> allocator = nullptr;
 
-  SubscriptionOptionsWithAllocator<Allocator>() {}
+  SubscriptionOptionsWithAllocator() {}
 
   /// Constructor using base class as input.
   explicit SubscriptionOptionsWithAllocator(
@@ -110,7 +110,6 @@ struct SubscriptionOptionsWithAllocator : public SubscriptionOptionsBase
    * \param qos QoS profile for subcription.
    * \return rcl_subscription_options_t structure based on the rclcpp::QoS
    */
-  template<typename MessageT>
   rcl_subscription_options_t
   to_rcl_subscription_options(const rclcpp::QoS & qos) const
   {

rclcpp/include/rclcpp/timer.hpp

@@ -149,11 +149,48 @@ public:
   bool
   exchange_in_use_by_wait_set_state(bool in_use_state);
 
+  /// Set a callback to be called when the timer is reset
+  /**
+   * You should aim to make this callback fast and not blocking.
+   * If you need to do a lot of work or wait for some other event, you should
+   * spin it off to another thread.
+   *
+   * Calling it again will override any previously set callback.
+   * An exception will be thrown if the callback is not callable.
+   *
+   * This function is thread-safe.
+   *
+   * If you want more information available in the callback,
+   * you may use a lambda with captures or std::bind.
+   *
+   * \param[in] callback functor to be called whenever timer is reset
+   */
+  RCLCPP_PUBLIC
+  void
+  set_on_reset_callback(std::function<void(size_t)> callback);
+
+  /// Unset the callback registered for reset timer
+  RCLCPP_PUBLIC
+  void
+  clear_on_reset_callback();
+
 protected:
+  std::recursive_mutex callback_mutex_;
+  // Declare callback before timer_handle_, so on destruction
+  // the callback is destroyed last. Otherwise, the rcl timer
+  // callback would point briefly to a destroyed function.
+  // Clearing the callback on timer destructor also makes sure
+  // the rcl callback is cleared before on_reset_callback_.
+  std::function<void(size_t)> on_reset_callback_{nullptr};
+
   Clock::SharedPtr clock_;
   std::shared_ptr<rcl_timer_t> timer_handle_;
 
   std::atomic<bool> in_use_by_wait_set_{false};
+
+  RCLCPP_PUBLIC
+  void
+  set_on_reset_callback(rcl_event_callback_t callback, const void * user_data);
 };
 
 
@@ -189,10 +226,10 @@ public:
     TRACEPOINT(
       rclcpp_timer_callback_added,
       static_cast<const void *>(get_timer_handle().get()),
-      static_cast<const void *>(&callback_));
+      reinterpret_cast<const void *>(&callback_));
     TRACEPOINT(
       rclcpp_callback_register,
-      static_cast<const void *>(&callback_),
+      reinterpret_cast<const void *>(&callback_),
       tracetools::get_symbol(callback_));
   }
 
@@ -226,9 +263,9 @@ public:
   void
   execute_callback() override
   {
-    TRACEPOINT(callback_start, static_cast<const void *>(&callback_), false);
+    TRACEPOINT(callback_start, reinterpret_cast<const void *>(&callback_), false);
     execute_callback_delegate<>();
-    TRACEPOINT(callback_end, static_cast<const void *>(&callback_));
+    TRACEPOINT(callback_end, reinterpret_cast<const void *>(&callback_));
   }
 
   // void specialization

rclcpp/include/rclcpp/utilities.hpp

@@ -169,7 +169,7 @@ remove_ros_arguments(int argc, char const * const * argv);
  * the context initialized by rclcpp::init().
  *
  * \param[in] context Optional check for shutdown of this Context.
- * \return true if shutdown has been called, false otherwise
+ * \return false if shutdown has been called, true otherwise
  */
 RCLCPP_PUBLIC
 bool

rclcpp/package.xml

@@ -2,13 +2,17 @@
 <?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>16.0.1</version>
+  <version>19.2.0</version>
   <description>The ROS client library in C++.</description>
+
   <maintainer email="ivanpauno@ekumenlabs.com">Ivan Paunovic</maintainer>
-  <maintainer email="jacob@openrobotics.org">Jacob Perron</maintainer>
+  <maintainer email="michel@ekumenlabs.com">Michel Hidalgo</maintainer>
   <maintainer email="william@openrobotics.org">William Woodall</maintainer>
+
   <license>Apache License 2.0</license>
+
   <author email="dthomas@openrobotics.org">Dirk Thomas</author>
+  <author email="jacob@openrobotics.org">Jacob Perron</author>
 
   <buildtool_depend>ament_cmake_ros</buildtool_depend>
   <buildtool_depend>ament_cmake_gen_version_h</buildtool_depend>

rclcpp/resource/logging.hpp.em

@@ -114,7 +114,6 @@ def get_rclcpp_suffix_from_features(features):
 @[ end for]@
 @[ if 'stream' not in feature_combination]@
  * \param ... The format string, followed by the variable arguments for the format string.
- * It also accepts a single argument of type std::string.
 @[ end if]@
  */
 @{params = rclcpp_feature_combinations[feature_combination].params.keys()}@
@@ -125,7 +124,7 @@ def get_rclcpp_suffix_from_features(features):
 ) \
   do { \
     static_assert( \
-      ::std::is_same<typename std::remove_cv<typename std::remove_reference<decltype(logger)>::type>::type, \
+      ::std::is_same<typename std::remove_cv_t<typename std::remove_reference_t<decltype(logger)>>, \
       typename ::rclcpp::Logger>::value, \
       "First argument to logging macros must be an rclcpp::Logger"); \
 @[ if 'throttle' in feature_combination]@ \

rclcpp/src/rclcpp/callback_group.cpp

@@ -12,9 +12,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "rclcpp/callback_group.hpp"
+#include <algorithm>
+#include <atomic>
+#include <functional>
+#include <memory>
+#include <mutex>
+#include <stdexcept>
 
-#include <vector>
+#include "rclcpp/callback_group.hpp"
+#include "rclcpp/client.hpp"
+#include "rclcpp/service.hpp"
+#include "rclcpp/subscription_base.hpp"
+#include "rclcpp/timer.hpp"
+#include "rclcpp/waitable.hpp"
 
 using rclcpp::CallbackGroup;
 using rclcpp::CallbackGroupType;
@@ -27,6 +37,10 @@ CallbackGroup::CallbackGroup(
   automatically_add_to_executor_with_node_(automatically_add_to_executor_with_node)
 {}
 
+CallbackGroup::~CallbackGroup()
+{
+  trigger_notify_guard_condition();
+}
 
 std::atomic_bool &
 CallbackGroup::can_be_taken_from()
@@ -97,6 +111,33 @@ CallbackGroup::automatically_add_to_executor_with_node() const
   return automatically_add_to_executor_with_node_;
 }
 
+rclcpp::GuardCondition::SharedPtr
+CallbackGroup::get_notify_guard_condition(const rclcpp::Context::SharedPtr context_ptr)
+{
+  std::lock_guard<std::recursive_mutex> lock(notify_guard_condition_mutex_);
+  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_;
+}
+
+void
+CallbackGroup::trigger_notify_guard_condition()
+{
+  std::lock_guard<std::recursive_mutex> lock(notify_guard_condition_mutex_);
+  if (notify_guard_condition_) {
+    notify_guard_condition_->trigger();
+  }
+}
+
 void
 CallbackGroup::add_subscription(
   const rclcpp::SubscriptionBase::SharedPtr subscription_ptr)

rclcpp/src/rclcpp/client.cpp

@@ -65,13 +65,6 @@ ClientBase::ClientBase(
     });
 }
 
-ClientBase::~ClientBase()
-{
-  clear_on_new_response_callback();
-  // Make sure the client handle is destructed as early as possible and before the node handle
-  client_handle_.reset();
-}
-
 bool
 ClientBase::take_type_erased_response(void * response_out, rmw_request_id_t & request_header_out)
 {

rclcpp/src/rclcpp/clock.cpp

@@ -67,7 +67,7 @@ Clock::Clock(rcl_clock_type_t clock_type)
 Clock::~Clock() {}
 
 Time
-Clock::now()
+Clock::now() const
 {
   Time now(0, 0, impl_->rcl_clock_.type);
 
@@ -182,6 +182,71 @@ Clock::sleep_for(Duration rel_time, Context::SharedPtr context)
   return sleep_until(now() + rel_time, context);
 }
 
+bool
+Clock::started()
+{
+  if (!rcl_clock_valid(get_clock_handle())) {
+    throw std::runtime_error("clock is not rcl_clock_valid");
+  }
+  return rcl_clock_time_started(get_clock_handle());
+}
+
+bool
+Clock::wait_until_started(Context::SharedPtr context)
+{
+  if (!context || !context->is_valid()) {
+    throw std::runtime_error("context cannot be slept with because it's invalid");
+  }
+  if (!rcl_clock_valid(get_clock_handle())) {
+    throw std::runtime_error("clock cannot be waited on as it is not rcl_clock_valid");
+  }
+
+  if (started()) {
+    return true;
+  } else {
+    // Wait until the first non-zero time
+    return sleep_until(rclcpp::Time(0, 1, get_clock_type()), context);
+  }
+}
+
+bool
+Clock::wait_until_started(
+  const Duration & timeout,
+  Context::SharedPtr context,
+  const Duration & wait_tick_ns)
+{
+  if (!context || !context->is_valid()) {
+    throw std::runtime_error("context cannot be slept with because it's invalid");
+  }
+  if (!rcl_clock_valid(get_clock_handle())) {
+    throw std::runtime_error("clock cannot be waited on as it is not rcl_clock_valid");
+  }
+
+  Clock timeout_clock = Clock(RCL_STEADY_TIME);
+  Time start = timeout_clock.now();
+
+  // Check if the clock has started every wait_tick_ns nanoseconds
+  // Context check checks for rclcpp::shutdown()
+  while (!started() && context->is_valid()) {
+    if (timeout < wait_tick_ns) {
+      timeout_clock.sleep_for(timeout);
+    } else {
+      Duration time_left = start + timeout - timeout_clock.now();
+      if (time_left > wait_tick_ns) {
+        timeout_clock.sleep_for(Duration(wait_tick_ns));
+      } else {
+        timeout_clock.sleep_for(time_left);
+      }
+    }
+
+    if (timeout_clock.now() - start > timeout) {
+      return started();
+    }
+  }
+  return started();
+}
+
+
 bool
 Clock::ros_time_is_active()
 {

rclcpp/src/rclcpp/context.cpp

@@ -154,7 +154,9 @@ Context::~Context()
   // this will not prevent errors, but will maybe make them easier to reproduce
   std::lock_guard<std::recursive_mutex> lock(init_mutex_);
   try {
-    this->shutdown("context destructor was called while still not shutdown");
+    // Cannot rely on virtual dispatch in a destructor, so explicitly use the
+    // shutdown() provided by this base class.
+    Context::shutdown("context destructor was called while still not shutdown");
     // at this point it is shutdown and cannot reinit
     // clean_up will finalize the rcl context
     this->clean_up();
@@ -363,49 +365,45 @@ Context::on_shutdown(OnShutdownCallback callback)
 rclcpp::OnShutdownCallbackHandle
 Context::add_on_shutdown_callback(OnShutdownCallback callback)
 {
-  return add_shutdown_callback(ShutdownType::on_shutdown, callback);
+  return add_shutdown_callback<ShutdownType::on_shutdown>(callback);
 }
 
 bool
 Context::remove_on_shutdown_callback(const OnShutdownCallbackHandle & callback_handle)
 {
-  return remove_shutdown_callback(ShutdownType::on_shutdown, callback_handle);
+  return remove_shutdown_callback<ShutdownType::on_shutdown>(callback_handle);
 }
 
 rclcpp::PreShutdownCallbackHandle
 Context::add_pre_shutdown_callback(PreShutdownCallback callback)
 {
-  return add_shutdown_callback(ShutdownType::pre_shutdown, callback);
+  return add_shutdown_callback<ShutdownType::pre_shutdown>(callback);
 }
 
 bool
 Context::remove_pre_shutdown_callback(
   const PreShutdownCallbackHandle & callback_handle)
 {
-  return remove_shutdown_callback(ShutdownType::pre_shutdown, callback_handle);
+  return remove_shutdown_callback<ShutdownType::pre_shutdown>(callback_handle);
 }
 
+template<Context::ShutdownType shutdown_type>
 rclcpp::ShutdownCallbackHandle
 Context::add_shutdown_callback(
-  ShutdownType shutdown_type,
   ShutdownCallback callback)
 {
   auto callback_shared_ptr =
     std::make_shared<ShutdownCallbackHandle::ShutdownCallbackType>(callback);
 
-  switch (shutdown_type) {
-    case ShutdownType::pre_shutdown:
-      {
-        std::lock_guard<std::mutex> lock(pre_shutdown_callbacks_mutex_);
-        pre_shutdown_callbacks_.emplace(callback_shared_ptr);
-      }
-      break;
-    case ShutdownType::on_shutdown:
-      {
-        std::lock_guard<std::mutex> lock(on_shutdown_callbacks_mutex_);
-        on_shutdown_callbacks_.emplace(callback_shared_ptr);
-      }
-      break;
+  static_assert(
+    shutdown_type == ShutdownType::pre_shutdown || shutdown_type == ShutdownType::on_shutdown);
+
+  if constexpr (shutdown_type == ShutdownType::pre_shutdown) {
+    std::lock_guard<std::mutex> lock(pre_shutdown_callbacks_mutex_);
+    pre_shutdown_callbacks_.emplace_back(callback_shared_ptr);
+  } else {
+    std::lock_guard<std::mutex> lock(on_shutdown_callbacks_mutex_);
+    on_shutdown_callbacks_.emplace_back(callback_shared_ptr);
   }
 
   ShutdownCallbackHandle callback_handle;
@@ -413,73 +411,74 @@ Context::add_shutdown_callback(
   return callback_handle;
 }
 
+template<Context::ShutdownType shutdown_type>
 bool
 Context::remove_shutdown_callback(
-  ShutdownType shutdown_type,
   const ShutdownCallbackHandle & callback_handle)
 {
-  std::mutex * mutex_ptr = nullptr;
-  std::unordered_set<
-    std::shared_ptr<ShutdownCallbackHandle::ShutdownCallbackType>> * callback_list_ptr;
-
-  switch (shutdown_type) {
-    case ShutdownType::pre_shutdown:
-      mutex_ptr = &pre_shutdown_callbacks_mutex_;
-      callback_list_ptr = &pre_shutdown_callbacks_;
-      break;
-    case ShutdownType::on_shutdown:
-      mutex_ptr = &on_shutdown_callbacks_mutex_;
-      callback_list_ptr = &on_shutdown_callbacks_;
-      break;
-  }
-
-  std::lock_guard<std::mutex> lock(*mutex_ptr);
-  auto callback_shared_ptr = callback_handle.callback.lock();
+  const auto callback_shared_ptr = callback_handle.callback.lock();
   if (callback_shared_ptr == nullptr) {
     return false;
   }
-  return callback_list_ptr->erase(callback_shared_ptr) == 1;
+
+  const auto remove_callback = [&callback_shared_ptr](auto & mutex, auto & callback_vector) {
+      const std::lock_guard<std::mutex> lock(mutex);
+      auto iter = callback_vector.begin();
+      for (; iter != callback_vector.end(); iter++) {
+        if ((*iter).get() == callback_shared_ptr.get()) {
+          break;
+        }
+      }
+      if (iter == callback_vector.end()) {
+        return false;
+      }
+      callback_vector.erase(iter);
+      return true;
+    };
+
+  static_assert(
+    shutdown_type == ShutdownType::pre_shutdown || shutdown_type == ShutdownType::on_shutdown);
+
+  if constexpr (shutdown_type == ShutdownType::pre_shutdown) {
+    return remove_callback(pre_shutdown_callbacks_mutex_, pre_shutdown_callbacks_);
+  } else {
+    return remove_callback(on_shutdown_callbacks_mutex_, on_shutdown_callbacks_);
+  }
 }
 
 std::vector<rclcpp::Context::OnShutdownCallback>
 Context::get_on_shutdown_callbacks() const
 {
-  return get_shutdown_callback(ShutdownType::on_shutdown);
+  return get_shutdown_callback<ShutdownType::on_shutdown>();
 }
 
 std::vector<rclcpp::Context::PreShutdownCallback>
 Context::get_pre_shutdown_callbacks() const
 {
-  return get_shutdown_callback(ShutdownType::pre_shutdown);
+  return get_shutdown_callback<ShutdownType::pre_shutdown>();
 }
 
+template<Context::ShutdownType shutdown_type>
 std::vector<rclcpp::Context::ShutdownCallback>
-Context::get_shutdown_callback(ShutdownType shutdown_type) const
+Context::get_shutdown_callback() const
 {
-  std::mutex * mutex_ptr = nullptr;
-  const std::unordered_set<
-    std::shared_ptr<ShutdownCallbackHandle::ShutdownCallbackType>> * callback_list_ptr;
+  const auto get_callback_vector = [this](auto & mutex, auto & callback_set) {
+      const std::lock_guard<std::mutex> lock(mutex);
+      std::vector<rclcpp::Context::ShutdownCallback> callbacks;
+      for (auto & callback : callback_set) {
+        callbacks.push_back(*callback);
+      }
+      return callbacks;
+    };
 
-  switch (shutdown_type) {
-    case ShutdownType::pre_shutdown:
-      mutex_ptr = &pre_shutdown_callbacks_mutex_;
-      callback_list_ptr = &pre_shutdown_callbacks_;
-      break;
-    case ShutdownType::on_shutdown:
-      mutex_ptr = &on_shutdown_callbacks_mutex_;
-      callback_list_ptr = &on_shutdown_callbacks_;
-      break;
+  static_assert(
+    shutdown_type == ShutdownType::pre_shutdown || shutdown_type == ShutdownType::on_shutdown);
+
+  if constexpr (shutdown_type == ShutdownType::pre_shutdown) {
+    return get_callback_vector(pre_shutdown_callbacks_mutex_, pre_shutdown_callbacks_);
+  } else {
+    return get_callback_vector(on_shutdown_callbacks_mutex_, on_shutdown_callbacks_);
   }
-
-  std::vector<rclcpp::Context::ShutdownCallback> callbacks;
-  {
-    std::lock_guard<std::mutex> lock(*mutex_ptr);
-    for (auto & iter : *callback_list_ptr) {
-      callbacks.emplace_back(*iter);
-    }
-  }
-
-  return callbacks;
 }
 
 std::shared_ptr<rcl_context_t>

rclcpp/src/rclcpp/detail/resolve_parameter_overrides.cpp

@@ -51,18 +51,13 @@ rclcpp::detail::resolve_parameter_overrides(
         [params]() {
           rcl_yaml_node_struct_fini(params);
         });
-      rclcpp::ParameterMap initial_map = rclcpp::parameter_map_from(params);
+      rclcpp::ParameterMap initial_map = rclcpp::parameter_map_from(params, node_fqn.c_str());
 
-      // Enforce wildcard matching precedence
-      // TODO(cottsay) implement further wildcard matching
-      const std::array<std::string, 2> node_matching_names{"/**", node_fqn};
-      for (const auto & node_name : node_matching_names) {
-        if (initial_map.count(node_name) > 0) {
-          // Combine parameter yaml files, overwriting values in older ones
-          for (const rclcpp::Parameter & param : initial_map.at(node_name)) {
-            result[param.get_name()] =
-              rclcpp::ParameterValue(param.get_value_message());
-          }
+      if (initial_map.count(node_fqn) > 0) {
+        // Combine parameter yaml files, overwriting values in older ones
+        for (const rclcpp::Parameter & param : initial_map.at(node_fqn)) {
+          result[param.get_name()] =
+            rclcpp::ParameterValue(param.get_value_message());
         }
       }
     }

rclcpp/src/rclcpp/duration.cpp

@@ -161,6 +161,13 @@ Duration::operator+(const rclcpp::Duration & rhs) const
     rcl_duration_.nanoseconds + rhs.rcl_duration_.nanoseconds);
 }
 
+Duration &
+Duration::operator+=(const rclcpp::Duration & rhs)
+{
+  *this = *this + rhs;
+  return *this;
+}
+
 void
 bounds_check_duration_difference(int64_t lhsns, int64_t rhsns, uint64_t max)
 {
@@ -190,6 +197,13 @@ Duration::operator-(const rclcpp::Duration & rhs) const
     rcl_duration_.nanoseconds - rhs.rcl_duration_.nanoseconds);
 }
 
+Duration &
+Duration::operator-=(const rclcpp::Duration & rhs)
+{
+  *this = *this - rhs;
+  return *this;
+}
+
 void
 bounds_check_duration_scale(int64_t dns, double scale, uint64_t max)
 {
@@ -222,6 +236,13 @@ Duration::operator*(double scale) const
       static_cast<long double>(rcl_duration_.nanoseconds) * scale_ld));
 }
 
+Duration &
+Duration::operator*=(double scale)
+{
+  *this = *this * scale;
+  return *this;
+}
+
 rcl_duration_value_t
 Duration::nanoseconds() const
 {

rclcpp/src/rclcpp/executor.cpp

@@ -106,6 +106,12 @@ Executor::~Executor()
   weak_groups_associated_with_executor_to_nodes_.clear();
   weak_groups_to_nodes_associated_with_executor_.clear();
   weak_groups_to_nodes_.clear();
+  for (const auto & pair : weak_groups_to_guard_conditions_) {
+    auto guard_condition = pair.second;
+    memory_strategy_->remove_guard_condition(guard_condition);
+  }
+  weak_groups_to_guard_conditions_.clear();
+
   for (const auto & pair : weak_nodes_to_guard_conditions_) {
     auto guard_condition = pair.second;
     memory_strategy_->remove_guard_condition(guard_condition);
@@ -204,8 +210,7 @@ Executor::add_callback_group_to_map(
   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_to_nodes_associated_with_executor_) &&
-    !has_node(node_ptr, weak_groups_associated_with_executor_to_nodes_);
+
   rclcpp::CallbackGroup::WeakPtr weak_group_ptr = group_ptr;
   auto insert_info =
     weak_groups_to_nodes.insert(std::make_pair(weak_group_ptr, node_ptr));
@@ -215,21 +220,24 @@ Executor::add_callback_group_to_map(
   }
   // Also add to the map that contains all callback groups
   weak_groups_to_nodes_.insert(std::make_pair(weak_group_ptr, node_ptr));
-  if (is_new_node) {
-    const auto & gc = node_ptr->get_notify_guard_condition();
-    weak_nodes_to_guard_conditions_[node_ptr] = &gc;
-    if (notify) {
-      // Interrupt waiting to handle new node
-      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 add: ") + ex.what());
-      }
+
+  if (node_ptr->get_context()->is_valid()) {
+    auto callback_group_guard_condition =
+      group_ptr->get_notify_guard_condition(node_ptr->get_context());
+    weak_groups_to_guard_conditions_[weak_group_ptr] = callback_group_guard_condition.get();
+    // Add the callback_group's notify condition to the guard condition handles
+    memory_strategy_->add_guard_condition(*callback_group_guard_condition);
+  }
+
+  if (notify) {
+    // Interrupt waiting to handle new node
+    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 add: ") + ex.what());
     }
-    // Add the node's notify condition to the guard condition handles
-    memory_strategy_->add_guard_condition(gc);
   }
 }
 
@@ -272,6 +280,10 @@ Executor::add_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_pt
       }
     });
 
+  const auto & gc = node_ptr->get_notify_guard_condition();
+  weak_nodes_to_guard_conditions_[node_ptr] = &gc;
+  // Add the node's notify condition to the guard condition handles
+  memory_strategy_->add_guard_condition(gc);
   weak_nodes_.push_back(node_ptr);
 }
 
@@ -300,7 +312,12 @@ Executor::remove_callback_group_from_map(
   if (!has_node(node_ptr, weak_groups_to_nodes_associated_with_executor_) &&
     !has_node(node_ptr, weak_groups_associated_with_executor_to_nodes_))
   {
-    weak_nodes_to_guard_conditions_.erase(node_ptr);
+    auto iter = weak_groups_to_guard_conditions_.find(weak_group_ptr);
+    if (iter != weak_groups_to_guard_conditions_.end()) {
+      memory_strategy_->remove_guard_condition(iter->second);
+    }
+    weak_groups_to_guard_conditions_.erase(weak_group_ptr);
+
     if (notify) {
       try {
         interrupt_guard_condition_.trigger();
@@ -310,7 +327,6 @@ Executor::remove_callback_group_from_map(
                   "Failed to trigger guard condition on callback group remove: ") + ex.what());
       }
     }
-    memory_strategy_->remove_guard_condition(&node_ptr->get_notify_guard_condition());
   }
 }
 
@@ -372,6 +388,9 @@ Executor::remove_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node
     }
   }
 
+  memory_strategy_->remove_guard_condition(&node_ptr->get_notify_guard_condition());
+  weak_nodes_to_guard_conditions_.erase(node_ptr);
+
   std::atomic_bool & has_executor = node_ptr->get_associated_with_executor_atomic();
   has_executor.store(false);
 }
@@ -721,6 +740,12 @@ Executor::wait_for_work(std::chrono::nanoseconds timeout)
           {
             weak_groups_associated_with_executor_to_nodes_.erase(group_ptr);
           }
+          auto callback_guard_pair = weak_groups_to_guard_conditions_.find(group_ptr);
+          if (callback_guard_pair != weak_groups_to_guard_conditions_.end()) {
+            auto guard_condition = callback_guard_pair->second;
+            weak_groups_to_guard_conditions_.erase(group_ptr);
+            memory_strategy_->remove_guard_condition(guard_condition);
+          }
           weak_groups_to_nodes_.erase(group_ptr);
         });
     }

rclcpp/src/rclcpp/executors/multi_threaded_executor.cpp

@@ -21,6 +21,7 @@
 
 #include "rcpputils/scope_exit.hpp"
 
+#include "rclcpp/logging.hpp"
 #include "rclcpp/utilities.hpp"
 
 using rclcpp::executors::MultiThreadedExecutor;
@@ -34,9 +35,15 @@ MultiThreadedExecutor::MultiThreadedExecutor(
   yield_before_execute_(yield_before_execute),
   next_exec_timeout_(next_exec_timeout)
 {
-  number_of_threads_ = number_of_threads ? number_of_threads : std::thread::hardware_concurrency();
-  if (number_of_threads_ == 0) {
-    number_of_threads_ = 1;
+  number_of_threads_ = number_of_threads > 0 ?
+    number_of_threads :
+    std::max(std::thread::hardware_concurrency(), 2U);
+
+  if (number_of_threads_ == 1) {
+    RCLCPP_WARN(
+      rclcpp::get_logger("rclcpp"),
+      "MultiThreadedExecutor is used with a single thread.\n"
+      "Use the SingleThreadedExecutor instead.");
   }
 }
 

rclcpp/src/rclcpp/graph_listener.cpp

@@ -48,7 +48,7 @@ GraphListener::GraphListener(const std::shared_ptr<Context> & parent_context)
 
 GraphListener::~GraphListener()
 {
-  this->shutdown(std::nothrow);
+  GraphListener::shutdown(std::nothrow);
 }
 
 void GraphListener::init_wait_set()

rclcpp/src/rclcpp/guard_condition.cpp

@@ -74,16 +74,19 @@ GuardCondition::get_rcl_guard_condition() const
 void
 GuardCondition::trigger()
 {
-  std::lock_guard<std::recursive_mutex> lock(reentrant_mutex_);
+  rcl_ret_t ret = rcl_trigger_guard_condition(&rcl_guard_condition_);
+  if (RCL_RET_OK != ret) {
+    rclcpp::exceptions::throw_from_rcl_error(ret);
+  }
 
-  if (on_trigger_callback_) {
-    on_trigger_callback_(1);
-  } else {
-    rcl_ret_t ret = rcl_trigger_guard_condition(&rcl_guard_condition_);
-    if (RCL_RET_OK != ret) {
-      rclcpp::exceptions::throw_from_rcl_error(ret);
+  {
+    std::lock_guard<std::recursive_mutex> lock(reentrant_mutex_);
+
+    if (on_trigger_callback_) {
+      on_trigger_callback_(1);
+    } else {
+      unread_count_++;
     }
-    unread_count_++;
   }
 }
 
@@ -125,10 +128,9 @@ GuardCondition::set_on_trigger_callback(std::function<void(size_t)> callback)
       callback(unread_count_);
       unread_count_ = 0;
     }
-    return;
+  } else {
+    on_trigger_callback_ = nullptr;
   }
-
-  on_trigger_callback_ = nullptr;
 }
 
 }  // namespace rclcpp

rclcpp/src/rclcpp/logger.cpp

@@ -12,14 +12,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include <memory>
 #include <string>
+#include <utility>
 
 #include "rcl_logging_interface/rcl_logging_interface.h"
+#include "rcl/logging_rosout.h"
 
 #include "rclcpp/exceptions.hpp"
 #include "rclcpp/logger.hpp"
 #include "rclcpp/logging.hpp"
 
+#include "./logging_mutex.hpp"
+
 namespace rclcpp
 {
 
@@ -62,6 +67,46 @@ get_logging_directory()
   return path;
 }
 
+Logger
+Logger::get_child(const std::string & suffix)
+{
+  if (!name_) {
+    return Logger();
+  }
+
+  rcl_ret_t rcl_ret = RCL_RET_OK;
+  std::shared_ptr<std::recursive_mutex> logging_mutex;
+  logging_mutex = get_global_logging_mutex();
+  {
+    std::lock_guard<std::recursive_mutex> guard(*logging_mutex);
+    rcl_ret = rcl_logging_rosout_add_sublogger((*name_).c_str(), suffix.c_str());
+    if (RCL_RET_OK != rcl_ret) {
+      exceptions::throw_from_rcl_error(
+        rcl_ret, "failed to call rcl_logging_rosout_add_sublogger",
+        rcutils_get_error_state(), rcutils_reset_error);
+    }
+  }
+
+  Logger logger(*name_ + RCUTILS_LOGGING_SEPARATOR_STRING + suffix);
+  if (RCL_RET_OK == rcl_ret) {
+    logger.logger_sublogger_pairname_.reset(
+      new std::pair<std::string, std::string>({*name_, suffix}),
+      [logging_mutex](std::pair<std::string, std::string> * logger_sublogger_pairname_ptr) {
+        std::lock_guard<std::recursive_mutex> guard(*logging_mutex);
+        rcl_ret_t rcl_ret = rcl_logging_rosout_remove_sublogger(
+          logger_sublogger_pairname_ptr->first.c_str(),
+          logger_sublogger_pairname_ptr->second.c_str());
+        delete logger_sublogger_pairname_ptr;
+        if (RCL_RET_OK != rcl_ret) {
+          exceptions::throw_from_rcl_error(
+            rcl_ret, "failed to call rcl_logging_rosout_remove_sublogger",
+            rcutils_get_error_state(), rcutils_reset_error);
+        }
+      });
+  }
+  return logger;
+}
+
 void
 Logger::set_level(Level level)
 {

rclcpp/src/rclcpp/node.cpp

@@ -176,7 +176,8 @@ Node::Node(
       node_topics_,
       node_graph_,
       node_services_,
-      node_logging_
+      node_logging_,
+      options.clock_type()
     )),
   node_parameters_(new rclcpp::node_interfaces::NodeParameters(
       node_base_,
@@ -353,7 +354,7 @@ Node::has_parameter(const std::string & name) const
 rcl_interfaces::msg::SetParametersResult
 Node::set_parameter(const rclcpp::Parameter & parameter)
 {
-  return this->set_parameters_atomically({parameter});
+  return node_parameters_->set_parameters_atomically({parameter});
 }
 
 std::vector<rcl_interfaces::msg::SetParametersResult>
@@ -418,16 +419,40 @@ Node::list_parameters(const std::vector<std::string> & prefixes, uint64_t depth)
   return node_parameters_->list_parameters(prefixes, depth);
 }
 
+rclcpp::Node::PreSetParametersCallbackHandle::SharedPtr
+Node::add_pre_set_parameters_callback(PreSetParametersCallbackType callback)
+{
+  return node_parameters_->add_pre_set_parameters_callback(callback);
+}
+
 rclcpp::Node::OnSetParametersCallbackHandle::SharedPtr
-Node::add_on_set_parameters_callback(OnParametersSetCallbackType callback)
+Node::add_on_set_parameters_callback(OnSetParametersCallbackType callback)
 {
   return node_parameters_->add_on_set_parameters_callback(callback);
 }
 
-void
-Node::remove_on_set_parameters_callback(const OnSetParametersCallbackHandle * const callback)
+rclcpp::Node::PostSetParametersCallbackHandle::SharedPtr
+Node::add_post_set_parameters_callback(PostSetParametersCallbackType callback)
 {
-  return node_parameters_->remove_on_set_parameters_callback(callback);
+  return node_parameters_->add_post_set_parameters_callback(callback);
+}
+
+void
+Node::remove_pre_set_parameters_callback(const PreSetParametersCallbackHandle * const handler)
+{
+  node_parameters_->remove_pre_set_parameters_callback(handler);
+}
+
+void
+Node::remove_on_set_parameters_callback(const OnSetParametersCallbackHandle * const handler)
+{
+  node_parameters_->remove_on_set_parameters_callback(handler);
+}
+
+void
+Node::remove_post_set_parameters_callback(const PostSetParametersCallbackHandle * const handler)
+{
+  node_parameters_->remove_post_set_parameters_callback(handler);
 }
 
 std::vector<std::string>

rclcpp/src/rclcpp/node_interfaces/node_base.cpp

@@ -37,12 +37,13 @@ NodeBase::NodeBase(
   rclcpp::Context::SharedPtr context,
   const rcl_node_options_t & rcl_node_options,
   bool use_intra_process_default,
-  bool enable_topic_statistics_default)
+  bool enable_topic_statistics_default,
+  rclcpp::CallbackGroup::SharedPtr default_callback_group)
 : context_(context),
   use_intra_process_default_(use_intra_process_default),
   enable_topic_statistics_default_(enable_topic_statistics_default),
   node_handle_(nullptr),
-  default_callback_group_(nullptr),
+  default_callback_group_(default_callback_group),
   associated_with_executor_(false),
   notify_guard_condition_(context),
   notify_guard_condition_is_valid_(false)
@@ -128,9 +129,12 @@ NodeBase::NodeBase(
       delete node;
     });
 
-  // Create the default callback group.
-  using rclcpp::CallbackGroupType;
-  default_callback_group_ = create_callback_group(CallbackGroupType::MutuallyExclusive);
+  // Create the default callback group, if needed.
+  if (nullptr == default_callback_group_) {
+    using rclcpp::CallbackGroupType;
+    default_callback_group_ =
+      NodeBase::create_callback_group(CallbackGroupType::MutuallyExclusive);
+  }
 
   // Indicate the notify_guard_condition is now valid.
   notify_guard_condition_is_valid_ = true;

rclcpp/src/rclcpp/node_interfaces/node_clock.cpp

@@ -24,13 +24,14 @@ NodeClock::NodeClock(
   rclcpp::node_interfaces::NodeTopicsInterface::SharedPtr node_topics,
   rclcpp::node_interfaces::NodeGraphInterface::SharedPtr node_graph,
   rclcpp::node_interfaces::NodeServicesInterface::SharedPtr node_services,
-  rclcpp::node_interfaces::NodeLoggingInterface::SharedPtr node_logging)
+  rclcpp::node_interfaces::NodeLoggingInterface::SharedPtr node_logging,
+  rcl_clock_type_t clock_type)
 : node_base_(node_base),
   node_topics_(node_topics),
   node_graph_(node_graph),
   node_services_(node_services),
   node_logging_(node_logging),
-  ros_clock_(std::make_shared<rclcpp::Clock>(RCL_ROS_TIME))
+  clock_(std::make_shared<rclcpp::Clock>(clock_type))
 {}
 
 NodeClock::~NodeClock()
@@ -39,11 +40,11 @@ NodeClock::~NodeClock()
 rclcpp::Clock::SharedPtr
 NodeClock::get_clock()
 {
-  return ros_clock_;
+  return clock_;
 }
 
 rclcpp::Clock::ConstSharedPtr
 NodeClock::get_clock() const
 {
-  return ros_clock_;
+  return clock_;
 }

rclcpp/src/rclcpp/node_interfaces/node_logging.cpp

@@ -19,7 +19,7 @@ using rclcpp::node_interfaces::NodeLogging;
 NodeLogging::NodeLogging(rclcpp::node_interfaces::NodeBaseInterface * node_base)
 : node_base_(node_base)
 {
-  logger_ = rclcpp::get_logger(this->get_logger_name());
+  logger_ = rclcpp::get_logger(NodeLogging::get_logger_name());
 }
 
 NodeLogging::~NodeLogging()

rclcpp/src/rclcpp/node_interfaces/node_parameters.cpp

@@ -39,6 +39,31 @@
 
 using rclcpp::node_interfaces::NodeParameters;
 
+RCLCPP_LOCAL
+void
+local_perform_automatically_declare_parameters_from_overrides(
+  const std::map<std::string, rclcpp::ParameterValue> & parameter_overrides,
+  std::function<bool(const std::string &)> has_parameter,
+  std::function<void(
+    const std::string &,
+    const rclcpp::ParameterValue &,
+    const rcl_interfaces::msg::ParameterDescriptor &,
+    bool)>
+  declare_parameter)
+{
+  rcl_interfaces::msg::ParameterDescriptor descriptor;
+  descriptor.dynamic_typing = true;
+  for (const auto & pair : parameter_overrides) {
+    if (!has_parameter(pair.first)) {
+      declare_parameter(
+        pair.first,
+        pair.second,
+        descriptor,
+        true);
+    }
+  }
+}
+
 NodeParameters::NodeParameters(
   const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_base,
   const rclcpp::node_interfaces::NodeLoggingInterface::SharedPtr node_logging,
@@ -101,20 +126,43 @@ NodeParameters::NodeParameters(
   // If asked, initialize any parameters that ended up in the initial parameter values,
   // but did not get declared explcitily by this point.
   if (automatically_declare_parameters_from_overrides) {
-    rcl_interfaces::msg::ParameterDescriptor descriptor;
-    descriptor.dynamic_typing = true;
-    for (const auto & pair : this->get_parameter_overrides()) {
-      if (!this->has_parameter(pair.first)) {
-        this->declare_parameter(
-          pair.first,
-          pair.second,
-          descriptor,
-          true);
+    using namespace std::placeholders;
+    local_perform_automatically_declare_parameters_from_overrides(
+      this->get_parameter_overrides(),
+      std::bind(&NodeParameters::has_parameter, this, _1),
+      [this](
+        const std::string & name,
+        const rclcpp::ParameterValue & default_value,
+        const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor,
+        bool ignore_override)
+      {
+        NodeParameters::declare_parameter(
+          name, default_value, parameter_descriptor, ignore_override);
       }
-    }
+    );
   }
 }
 
+void
+NodeParameters::perform_automatically_declare_parameters_from_overrides()
+{
+  local_perform_automatically_declare_parameters_from_overrides(
+    this->get_parameter_overrides(),
+    [this](const std::string & name) {
+      return this->has_parameter(name);
+    },
+    [this](
+      const std::string & name,
+      const rclcpp::ParameterValue & default_value,
+      const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor,
+      bool ignore_override)
+    {
+      this->declare_parameter(
+        name, default_value, parameter_descriptor, ignore_override);
+    }
+  );
+}
+
 NodeParameters::~NodeParameters()
 {}
 
@@ -257,19 +305,54 @@ __check_parameters(
   return result;
 }
 
-using OnParametersSetCallbackType =
-  rclcpp::node_interfaces::NodeParametersInterface::OnParametersSetCallbackType;
-using CallbacksContainerType =
-  rclcpp::node_interfaces::NodeParameters::CallbacksContainerType;
+using PreSetParametersCallbackType =
+  rclcpp::node_interfaces::NodeParametersInterface::PreSetParametersCallbackType;
+using PreSetParametersCallbackHandle =
+  rclcpp::node_interfaces::PreSetParametersCallbackHandle;
+using PreSetCallbacksHandleContainer =
+  rclcpp::node_interfaces::NodeParameters::PreSetCallbacksHandleContainer;
+
+using OnSetParametersCallbackType =
+  rclcpp::node_interfaces::NodeParametersInterface::OnSetParametersCallbackType;
 using OnSetParametersCallbackHandle =
   rclcpp::node_interfaces::OnSetParametersCallbackHandle;
+using OnSetCallbacksHandleContainer =
+  rclcpp::node_interfaces::NodeParameters::OnSetCallbacksHandleContainer;
+
+using PostSetParametersCallbackType =
+  rclcpp::node_interfaces::NodeParametersInterface::PostSetParametersCallbackType;
+using PostSetParametersCallbackHandle =
+  rclcpp::node_interfaces::PostSetParametersCallbackHandle;
+using PostSetCallbacksHandleContainer =
+  rclcpp::node_interfaces::NodeParameters::PostSetCallbacksHandleContainer;
+
+RCLCPP_LOCAL
+void
+__call_pre_set_parameters_callbacks(
+  std::vector<rclcpp::Parameter> & parameters,
+  PreSetCallbacksHandleContainer & callback_container)
+{
+  if (callback_container.empty()) {
+    return;
+  }
+
+  auto it = callback_container.begin();
+  while (it != callback_container.end()) {
+    auto shared_handle = it->lock();
+    if (nullptr != shared_handle) {
+      shared_handle->callback(parameters);
+      it++;
+    } else {
+      it = callback_container.erase(it);
+    }
+  }
+}
 
 RCLCPP_LOCAL
 rcl_interfaces::msg::SetParametersResult
-__call_on_parameters_set_callbacks(
+__call_on_set_parameters_callbacks(
   const std::vector<rclcpp::Parameter> & parameters,
-  CallbacksContainerType & callback_container,
-  const OnParametersSetCallbackType & callback)
+  OnSetCallbacksHandleContainer & callback_container)
 {
   rcl_interfaces::msg::SetParametersResult result;
   result.successful = true;
@@ -286,19 +369,37 @@ __call_on_parameters_set_callbacks(
       it = callback_container.erase(it);
     }
   }
-  if (callback) {
-    result = callback(parameters);
-  }
   return result;
 }
 
+RCLCPP_LOCAL
+void __call_post_set_parameters_callbacks(
+  const std::vector<rclcpp::Parameter> & parameters,
+  PostSetCallbacksHandleContainer & callback_container)
+{
+  if (callback_container.empty()) {
+    return;
+  }
+
+  auto it = callback_container.begin();
+  while (it != callback_container.end()) {
+    auto shared_handle = it->lock();
+    if (nullptr != shared_handle) {
+      shared_handle->callback(parameters);
+      it++;
+    } else {
+      it = callback_container.erase(it);
+    }
+  }
+}
+
 RCLCPP_LOCAL
 rcl_interfaces::msg::SetParametersResult
 __set_parameters_atomically_common(
   const std::vector<rclcpp::Parameter> & parameters,
   std::map<std::string, rclcpp::node_interfaces::ParameterInfo> & parameter_infos,
-  CallbacksContainerType & callback_container,
-  const OnParametersSetCallbackType & callback,
+  OnSetCallbacksHandleContainer & on_set_callback_container,
+  PostSetCallbacksHandleContainer & post_set_callback_container,
   bool allow_undeclared = false)
 {
   // Check if the value being set complies with the descriptor.
@@ -307,9 +408,9 @@ __set_parameters_atomically_common(
   if (!result.successful) {
     return result;
   }
-  // Call the user callback to see if the new value(s) are allowed.
+  // Call the user callbacks to see if the new value(s) are allowed.
   result =
-    __call_on_parameters_set_callbacks(parameters, callback_container, callback);
+    __call_on_set_parameters_callbacks(parameters, on_set_callback_container);
   if (!result.successful) {
     return result;
   }
@@ -321,6 +422,8 @@ __set_parameters_atomically_common(
       parameter_infos[name].descriptor.type = parameters[i].get_type();
       parameter_infos[name].value = parameters[i].get_parameter_value();
     }
+    // Call the user post set parameter callback
+    __call_post_set_parameters_callbacks(parameters, post_set_callback_container);
   }
 
   // Either way, return the result.
@@ -335,8 +438,8 @@ __declare_parameter_common(
   const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor,
   std::map<std::string, rclcpp::node_interfaces::ParameterInfo> & parameters_out,
   const std::map<std::string, rclcpp::ParameterValue> & overrides,
-  CallbacksContainerType & callback_container,
-  const OnParametersSetCallbackType & callback,
+  OnSetCallbacksHandleContainer & on_set_callback_container,
+  PostSetCallbacksHandleContainer & post_set_callback_container,
   rcl_interfaces::msg::ParameterEvent * parameter_event_out,
   bool ignore_override = false)
 {
@@ -366,14 +469,15 @@ __declare_parameter_common(
     return result;
   }
 
-  // Check with the user's callback to see if the initial value can be set.
+  // Check with the user's callbacks to see if the initial value can be set.
   std::vector<rclcpp::Parameter> parameter_wrappers {rclcpp::Parameter(name, *initial_value)};
   // This function also takes care of default vs initial value.
   auto result = __set_parameters_atomically_common(
     parameter_wrappers,
     parameter_infos,
-    callback_container,
-    callback);
+    on_set_callback_container,
+    post_set_callback_container
+  );
 
   if (!result.successful) {
     return result;
@@ -400,8 +504,8 @@ declare_parameter_helper(
   bool ignore_override,
   std::map<std::string, rclcpp::node_interfaces::ParameterInfo> & parameters,
   const std::map<std::string, rclcpp::ParameterValue> & overrides,
-  CallbacksContainerType & callback_container,
-  const OnParametersSetCallbackType & callback,
+  OnSetCallbacksHandleContainer & on_set_callback_container,
+  PostSetCallbacksHandleContainer & post_set_callback_container,
   rclcpp::Publisher<rcl_interfaces::msg::ParameterEvent> * events_publisher,
   const std::string & combined_name,
   rclcpp::node_interfaces::NodeClockInterface & node_clock)
@@ -437,8 +541,8 @@ declare_parameter_helper(
     parameter_descriptor,
     parameters,
     overrides,
-    callback_container,
-    callback,
+    on_set_callback_container,
+    post_set_callback_container,
     &parameter_event,
     ignore_override);
 
@@ -485,8 +589,8 @@ NodeParameters::declare_parameter(
     ignore_override,
     parameters_,
     parameter_overrides_,
-    on_parameters_set_callback_container_,
-    on_parameters_set_callback_,
+    on_set_parameters_callback_container_,
+    post_set_parameters_callback_container_,
     events_publisher_.get(),
     combined_name_,
     *node_clock_);
@@ -521,8 +625,8 @@ NodeParameters::declare_parameter(
     ignore_override,
     parameters_,
     parameter_overrides_,
-    on_parameters_set_callback_container_,
-    on_parameters_set_callback_,
+    on_set_parameters_callback_container_,
+    post_set_parameters_callback_container_,
     events_publisher_.get(),
     combined_name_,
     *node_clock_);
@@ -596,12 +700,27 @@ NodeParameters::set_parameters_atomically(const std::vector<rclcpp::Parameter> &
 
   rcl_interfaces::msg::SetParametersResult result;
 
+  // call any user registered pre set parameter callbacks
+  // this callback can make changes to the original parameters list
+  // also check if the changed parameter list is empty or not, if empty return
+  std::vector<rclcpp::Parameter> parameters_after_pre_set_callback(parameters);
+  __call_pre_set_parameters_callbacks(
+    parameters_after_pre_set_callback,
+    pre_set_parameters_callback_container_);
+
+  if (parameters_after_pre_set_callback.empty()) {
+    result.successful = false;
+    result.reason = "parameter list cannot be empty, this might be due to "
+      "pre_set_parameters_callback modifying the original parameters list.";
+    return result;
+  }
+
   // Check if any of the parameters are read-only, or if any parameters are not
   // declared.
   // If not declared, keep track of them in order to declare them later, when
   // undeclared parameters are allowed, and if they're not allowed, fail.
   std::vector<const rclcpp::Parameter *> parameters_to_be_declared;
-  for (const auto & parameter : parameters) {
+  for (const auto & parameter : parameters_after_pre_set_callback) {
     const std::string & name = parameter.get_name();
 
     // Check to make sure the parameter name is valid.
@@ -636,12 +755,13 @@ NodeParameters::set_parameters_atomically(const std::vector<rclcpp::Parameter> &
 
   // Declare parameters into a temporary "staging area", incase one of the declares fail.
   // We will use the staged changes as input to the "set atomically" action.
-  // We explicitly avoid calling the user callback here, so that it may be called once, with
+  // We explicitly avoid calling the user callbacks here, so that it may be called once, with
   // all the other parameters to be set (already declared parameters).
   std::map<std::string, rclcpp::node_interfaces::ParameterInfo> staged_parameter_changes;
   rcl_interfaces::msg::ParameterEvent parameter_event_msg;
   parameter_event_msg.node = combined_name_;
-  CallbacksContainerType empty_callback_container;
+  OnSetCallbacksHandleContainer empty_on_set_callback_container;
+  PostSetCallbacksHandleContainer empty_post_set_callback_container;
 
   // Implicit declare uses dynamic type descriptor.
   rcl_interfaces::msg::ParameterDescriptor descriptor;
@@ -656,8 +776,8 @@ NodeParameters::set_parameters_atomically(const std::vector<rclcpp::Parameter> &
       staged_parameter_changes,
       parameter_overrides_,
       // Only call callbacks once below
-      empty_callback_container,  // callback_container is explicitly empty
-      nullptr,  // callback is explicitly null.
+      empty_on_set_callback_container,   // callback_container is explicitly empty
+      empty_post_set_callback_container,  // callback_container is explicitly empty
       &parameter_event_msg,
       true);
     if (!result.successful) {
@@ -670,12 +790,14 @@ NodeParameters::set_parameters_atomically(const std::vector<rclcpp::Parameter> &
   // If there were implicitly declared parameters, then we may need to copy the input parameters
   // and then assign the value that was selected after the declare (could be affected by the
   // initial parameter values).
-  const std::vector<rclcpp::Parameter> * parameters_to_be_set = &parameters;
+  const std::vector<rclcpp::Parameter> * parameters_to_be_set = &parameters_after_pre_set_callback;
   std::vector<rclcpp::Parameter> parameters_copy;
   if (0 != staged_parameter_changes.size()) {  // If there were any implicitly declared parameters.
     bool any_initial_values_used = false;
     for (const auto & staged_parameter_change : staged_parameter_changes) {
-      auto it = __find_parameter_by_name(parameters, staged_parameter_change.first);
+      auto it = __find_parameter_by_name(
+        parameters_after_pre_set_callback,
+        staged_parameter_change.first);
       if (it->get_parameter_value() != staged_parameter_change.second.value) {
         // In this case, the value of the staged parameter differs from the
         // input from the user, and therefore we need to update things before setting.
@@ -685,7 +807,7 @@ NodeParameters::set_parameters_atomically(const std::vector<rclcpp::Parameter> &
       }
     }
     if (any_initial_values_used) {
-      parameters_copy = parameters;
+      parameters_copy = parameters_after_pre_set_callback;
       for (const auto & staged_parameter_change : staged_parameter_changes) {
         auto it = __find_parameter_by_name(parameters_copy, staged_parameter_change.first);
         *it = Parameter(staged_parameter_change.first, staged_parameter_change.second.value);
@@ -717,11 +839,10 @@ NodeParameters::set_parameters_atomically(const std::vector<rclcpp::Parameter> &
     *parameters_to_be_set,
     // they are actually set on the official parameter storage
     parameters_,
-    // this will get called once, with all the parameters to be set
-    on_parameters_set_callback_container_,
     // These callbacks are called once. When a callback returns an unsuccessful result,
-    // the remaining aren't called.
-    on_parameters_set_callback_,
+    // the remaining aren't called
+    on_set_parameters_callback_container_,
+    post_set_parameters_callback_container_,
     allow_undeclared_);  // allow undeclared
 
   // If not successful, then stop here.
@@ -777,29 +898,18 @@ NodeParameters::set_parameters_atomically(const std::vector<rclcpp::Parameter> &
     parameter_event_msg.stamp = node_clock_->get_clock()->now();
     events_publisher_->publish(parameter_event_msg);
   }
-
   return result;
 }
 
 std::vector<rclcpp::Parameter>
 NodeParameters::get_parameters(const std::vector<std::string> & names) const
 {
-  std::lock_guard<std::recursive_mutex> lock(mutex_);
   std::vector<rclcpp::Parameter> results;
   results.reserve(names.size());
 
+  std::lock_guard<std::recursive_mutex> lock(mutex_);
   for (auto & name : names) {
-    auto found_parameter = parameters_.find(name);
-    if (found_parameter != parameters_.cend()) {
-      // found
-      results.emplace_back(name, found_parameter->second.value);
-    } else if (this->allow_undeclared_) {
-      // not found, but undeclared allowed
-      results.emplace_back(name, rclcpp::ParameterValue());
-    } else {
-      // not found, and undeclared are not allowed
-      throw rclcpp::exceptions::ParameterNotDeclaredException(name);
-    }
+    results.emplace_back(this->get_parameter(name));
   }
   return results;
 }
@@ -810,18 +920,18 @@ NodeParameters::get_parameter(const std::string & name) const
   std::lock_guard<std::recursive_mutex> lock(mutex_);
 
   auto param_iter = parameters_.find(name);
-  if (
-    parameters_.end() != param_iter &&
-    (param_iter->second.value.get_type() != rclcpp::ParameterType::PARAMETER_NOT_SET ||
-    param_iter->second.descriptor.dynamic_typing))
-  {
-    return rclcpp::Parameter{name, param_iter->second.value};
-  } else if (this->allow_undeclared_) {
-    return rclcpp::Parameter{};
-  } else if (parameters_.end() == param_iter) {
-    throw rclcpp::exceptions::ParameterNotDeclaredException(name);
-  } else {
+  if (parameters_.end() != param_iter) {
+    if (
+      param_iter->second.value.get_type() != rclcpp::ParameterType::PARAMETER_NOT_SET ||
+      param_iter->second.descriptor.dynamic_typing)
+    {
+      return rclcpp::Parameter{name, param_iter->second.value};
+    }
     throw rclcpp::exceptions::ParameterUninitializedException(name);
+  } else if (this->allow_undeclared_) {
+    return rclcpp::Parameter{name};
+  } else {
+    throw rclcpp::exceptions::ParameterNotDeclaredException(name);
   }
 }
 
@@ -963,6 +1073,26 @@ NodeParameters::list_parameters(const std::vector<std::string> & prefixes, uint6
   return result;
 }
 
+void
+NodeParameters::remove_pre_set_parameters_callback(
+  const PreSetParametersCallbackHandle * const handle)
+{
+  std::lock_guard<std::recursive_mutex> lock(mutex_);
+  ParameterMutationRecursionGuard guard(parameter_modification_enabled_);
+
+  auto it = std::find_if(
+    pre_set_parameters_callback_container_.begin(),
+    pre_set_parameters_callback_container_.end(),
+    [handle](const auto & weak_handle) {
+      return handle == weak_handle.lock().get();
+    });
+  if (it != pre_set_parameters_callback_container_.end()) {
+    pre_set_parameters_callback_container_.erase(it);
+  } else {
+    throw std::runtime_error("Pre set parameter callback doesn't exist");
+  }
+}
+
 void
 NodeParameters::remove_on_set_parameters_callback(
   const OnSetParametersCallbackHandle * const handle)
@@ -971,20 +1101,53 @@ NodeParameters::remove_on_set_parameters_callback(
   ParameterMutationRecursionGuard guard(parameter_modification_enabled_);
 
   auto it = std::find_if(
-    on_parameters_set_callback_container_.begin(),
-    on_parameters_set_callback_container_.end(),
+    on_set_parameters_callback_container_.begin(),
+    on_set_parameters_callback_container_.end(),
     [handle](const auto & weak_handle) {
       return handle == weak_handle.lock().get();
     });
-  if (it != on_parameters_set_callback_container_.end()) {
-    on_parameters_set_callback_container_.erase(it);
+  if (it != on_set_parameters_callback_container_.end()) {
+    on_set_parameters_callback_container_.erase(it);
   } else {
-    throw std::runtime_error("Callback doesn't exist");
+    throw std::runtime_error("On set parameter callback doesn't exist");
   }
 }
 
+void
+NodeParameters::remove_post_set_parameters_callback(
+  const PostSetParametersCallbackHandle * const handle)
+{
+  std::lock_guard<std::recursive_mutex> lock(mutex_);
+  ParameterMutationRecursionGuard guard(parameter_modification_enabled_);
+
+  auto it = std::find_if(
+    post_set_parameters_callback_container_.begin(),
+    post_set_parameters_callback_container_.end(),
+    [handle](const auto & weak_handle) {
+      return handle == weak_handle.lock().get();
+    });
+  if (it != post_set_parameters_callback_container_.end()) {
+    post_set_parameters_callback_container_.erase(it);
+  } else {
+    throw std::runtime_error("Post set parameter callback doesn't exist");
+  }
+}
+
+PreSetParametersCallbackHandle::SharedPtr
+NodeParameters::add_pre_set_parameters_callback(PreSetParametersCallbackType callback)
+{
+  std::lock_guard<std::recursive_mutex> lock(mutex_);
+  ParameterMutationRecursionGuard guard(parameter_modification_enabled_);
+
+  auto handle = std::make_shared<PreSetParametersCallbackHandle>();
+  handle->callback = callback;
+  // the last callback registered is executed first.
+  pre_set_parameters_callback_container_.emplace_front(handle);
+  return handle;
+}
+
 OnSetParametersCallbackHandle::SharedPtr
-NodeParameters::add_on_set_parameters_callback(OnParametersSetCallbackType callback)
+NodeParameters::add_on_set_parameters_callback(OnSetParametersCallbackType callback)
 {
   std::lock_guard<std::recursive_mutex> lock(mutex_);
   ParameterMutationRecursionGuard guard(parameter_modification_enabled_);
@@ -992,7 +1155,21 @@ NodeParameters::add_on_set_parameters_callback(OnParametersSetCallbackType callb
   auto handle = std::make_shared<OnSetParametersCallbackHandle>();
   handle->callback = callback;
   // the last callback registered is executed first.
-  on_parameters_set_callback_container_.emplace_front(handle);
+  on_set_parameters_callback_container_.emplace_front(handle);
+  return handle;
+}
+
+PostSetParametersCallbackHandle::SharedPtr
+NodeParameters::add_post_set_parameters_callback(
+  PostSetParametersCallbackType callback)
+{
+  std::lock_guard<std::recursive_mutex> lock(mutex_);
+  ParameterMutationRecursionGuard guard(parameter_modification_enabled_);
+
+  auto handle = std::make_shared<PostSetParametersCallbackHandle>();
+  handle->callback = callback;
+  // the last callback registered is executed first.
+  post_set_parameters_callback_container_.emplace_front(handle);
   return handle;
 }
 

rclcpp/src/rclcpp/node_interfaces/node_services.cpp

@@ -35,15 +35,17 @@ NodeServices::add_service(
       // TODO(jacquelinekay): use custom exception
       throw std::runtime_error("Cannot create service, group not in node.");
     }
-    group->add_service(service_base_ptr);
   } else {
-    node_base_->get_default_callback_group()->add_service(service_base_ptr);
+    group = node_base_->get_default_callback_group();
   }
 
+  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();
+    group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(
             std::string("failed to notify wait set on service creation: ") + ex.what());
@@ -60,15 +62,17 @@ NodeServices::add_client(
       // TODO(jacquelinekay): use custom exception
       throw std::runtime_error("Cannot create client, group not in node.");
     }
-    group->add_client(client_base_ptr);
   } else {
-    node_base_->get_default_callback_group()->add_client(client_base_ptr);
+    group = node_base_->get_default_callback_group();
   }
 
+  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();
+    group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(
             std::string("failed to notify wait set on client creation: ") + ex.what());

rclcpp/src/rclcpp/node_interfaces/node_timers.cpp

@@ -37,14 +37,15 @@ NodeTimers::add_timer(
       // TODO(jacquelinekay): use custom exception
       throw std::runtime_error("Cannot create timer, group not in node.");
     }
-    callback_group->add_timer(timer);
   } else {
-    node_base_->get_default_callback_group()->add_timer(timer);
+    callback_group = node_base_->get_default_callback_group();
   }
+  callback_group->add_timer(timer);
 
   auto & node_gc = node_base_->get_notify_guard_condition();
   try {
     node_gc.trigger();
+    callback_group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(
             std::string("failed to notify wait set on timer creation: ") + ex.what());

rclcpp/src/rclcpp/node_interfaces/node_topics.cpp

@@ -73,6 +73,7 @@ NodeTopics::add_publisher(
   auto & node_gc = node_base_->get_notify_guard_condition();
   try {
     node_gc.trigger();
+    callback_group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(
             std::string("failed to notify wait set on publisher creation: ") + ex.what());
@@ -121,6 +122,7 @@ NodeTopics::add_subscription(
   auto & node_gc = node_base_->get_notify_guard_condition();
   try {
     node_gc.trigger();
+    callback_group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(
             std::string("failed to notify wait set on subscription creation: ") + ex.what());

rclcpp/src/rclcpp/node_interfaces/node_waitables.cpp

@@ -35,15 +35,17 @@ NodeWaitables::add_waitable(
       // TODO(jacobperron): use custom exception
       throw std::runtime_error("Cannot create waitable, group not in node.");
     }
-    group->add_waitable(waitable_ptr);
   } else {
-    node_base_->get_default_callback_group()->add_waitable(waitable_ptr);
+    group = node_base_->get_default_callback_group();
   }
 
+  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();
+    group->trigger_notify_guard_condition();
   } catch (const rclcpp::exceptions::RCLError & ex) {
     throw std::runtime_error(
             std::string("failed to notify wait set on waitable creation: ") + ex.what());

rclcpp/src/rclcpp/node_options.cpp

@@ -77,6 +77,7 @@ NodeOptions::operator=(const NodeOptions & other)
     this->enable_topic_statistics_ = other.enable_topic_statistics_;
     this->start_parameter_services_ = other.start_parameter_services_;
     this->start_parameter_event_publisher_ = other.start_parameter_event_publisher_;
+    this->clock_type_ = other.clock_type_;
     this->clock_qos_ = other.clock_qos_;
     this->use_clock_thread_ = other.use_clock_thread_;
     this->parameter_event_qos_ = other.parameter_event_qos_;
@@ -260,6 +261,19 @@ NodeOptions::start_parameter_event_publisher(bool start_parameter_event_publishe
   return *this;
 }
 
+const rcl_clock_type_t &
+NodeOptions::clock_type() const
+{
+  return this->clock_type_;
+}
+
+NodeOptions &
+NodeOptions::clock_type(const rcl_clock_type_t & clock_type)
+{
+  this->clock_type_ = clock_type;
+  return *this;
+}
+
 const rclcpp::QoS &
 NodeOptions::clock_qos() const
 {

rclcpp/src/rclcpp/parameter_client.cpp

@@ -35,7 +35,7 @@ AsyncParametersClient::AsyncParametersClient(
   const rclcpp::node_interfaces::NodeGraphInterface::SharedPtr node_graph_interface,
   const rclcpp::node_interfaces::NodeServicesInterface::SharedPtr node_services_interface,
   const std::string & remote_node_name,
-  const rmw_qos_profile_t & qos_profile,
+  const rclcpp::QoS & qos_profile,
   rclcpp::CallbackGroup::SharedPtr group)
 : node_topics_interface_(node_topics_interface)
 {
@@ -46,7 +46,7 @@ AsyncParametersClient::AsyncParametersClient(
   }
 
   rcl_client_options_t options = rcl_client_get_default_options();
-  options.qos = qos_profile;
+  options.qos = qos_profile.get_rmw_qos_profile();
 
   using rclcpp::Client;
   using rclcpp::ClientBase;
@@ -290,28 +290,24 @@ std::shared_future<std::vector<rcl_interfaces::msg::SetParametersResult>>
 AsyncParametersClient::load_parameters(
   const std::string & yaml_filename)
 {
-  rclcpp::ParameterMap parameter_map = rclcpp::parameter_map_from_yaml_file(yaml_filename);
-  return this->load_parameters(parameter_map);
+  rclcpp::ParameterMap parameter_map =
+    rclcpp::parameter_map_from_yaml_file(yaml_filename, remote_node_name_.c_str());
+
+  auto iter = parameter_map.find(remote_node_name_);
+  if (iter == parameter_map.end() || iter->second.size() == 0) {
+    throw rclcpp::exceptions::InvalidParametersException("No valid parameter");
+  }
+  auto future_result = set_parameters(iter->second);
+
+  return future_result;
 }
 
 std::shared_future<std::vector<rcl_interfaces::msg::SetParametersResult>>
 AsyncParametersClient::load_parameters(
   const rclcpp::ParameterMap & parameter_map)
 {
-  std::vector<rclcpp::Parameter> parameters;
-  std::string remote_name = remote_node_name_.substr(remote_node_name_.substr(1).find("/") + 2);
-  for (const auto & params : parameter_map) {
-    std::string node_full_name = params.first;
-    std::string node_name = node_full_name.substr(node_full_name.find("/*/") + 3);
-    if (node_full_name == remote_node_name_ ||
-      node_full_name == "/**" ||
-      (node_name == remote_name))
-    {
-      for (const auto & param : params.second) {
-        parameters.push_back(param);
-      }
-    }
-  }
+  std::vector<rclcpp::Parameter> parameters =
+    rclcpp::parameters_from_map(parameter_map, remote_node_name_.c_str());
 
   if (parameters.size() == 0) {
     throw rclcpp::exceptions::InvalidParametersException("No valid parameter");

rclcpp/src/rclcpp/parameter_event_handler.cpp

@@ -133,9 +133,13 @@ ParameterEventHandler::get_parameter_from_event(
 {
   rclcpp::Parameter p;
   if (!get_parameter_from_event(event, p, parameter_name, node_name)) {
-    throw std::runtime_error(
-            "Parameter '" + parameter_name + "' of node '" + node_name +
-            "' is not part of parameter event");
+    if (event.node == node_name) {
+      return rclcpp::Parameter(parameter_name, rclcpp::PARAMETER_NOT_SET);
+    } else {
+      throw std::runtime_error(
+              "The node name '" + node_name + "' of parameter '" + parameter_name +
+              +"' doesn't match the node name '" + event.node + "' in parameter event");
+    }
   }
   return p;
 }

rclcpp/src/rclcpp/parameter_map.cpp

@@ -13,8 +13,11 @@
 // limitations under the License.
 
 #include <string>
+#include <regex>
 #include <vector>
 
+#include "rcpputils/find_and_replace.hpp"
+#include "rcpputils/scope_exit.hpp"
 #include "rclcpp/parameter_map.hpp"
 
 using rclcpp::exceptions::InvalidParametersException;
@@ -22,8 +25,15 @@ using rclcpp::exceptions::InvalidParameterValueException;
 using rclcpp::ParameterMap;
 using rclcpp::ParameterValue;
 
+static bool is_node_name_matched(const std::string & node_name, const char * node_fqn)
+{
+  // Update the regular expression ["/*" -> "(/\\w+)" and "/**" -> "(/\\w+)*"]
+  std::string regex = rcpputils::find_and_replace(node_name, "/*", "(/\\w+)");
+  return std::regex_match(node_fqn, std::regex(regex));
+}
+
 ParameterMap
-rclcpp::parameter_map_from(const rcl_params_t * const c_params)
+rclcpp::parameter_map_from(const rcl_params_t * const c_params, const char * node_fqn)
 {
   if (NULL == c_params) {
     throw InvalidParametersException("parameters struct is NULL");
@@ -49,6 +59,15 @@ rclcpp::parameter_map_from(const rcl_params_t * const c_params)
       node_name = c_node_name;
     }
 
+    if (node_fqn) {
+      if (!is_node_name_matched(node_name, node_fqn)) {
+        // No need to parse the items because the user just care about node_fqn
+        continue;
+      }
+
+      node_name = node_fqn;
+    }
+
     const rcl_node_params_t * const c_params_node = &(c_params->params[n]);
 
     std::vector<Parameter> & params_node = parameters[node_name];
@@ -65,6 +84,7 @@ rclcpp::parameter_map_from(const rcl_params_t * const c_params)
       params_node.emplace_back(c_param_name, parameter_value_from(c_param_value));
     }
   }
+
   return parameters;
 }
 
@@ -128,13 +148,31 @@ rclcpp::parameter_value_from(const rcl_variant_t * const c_param_value)
 }
 
 ParameterMap
-rclcpp::parameter_map_from_yaml_file(const std::string & yaml_filename)
+rclcpp::parameter_map_from_yaml_file(const std::string & yaml_filename, const char * node_fqn)
 {
   rcutils_allocator_t allocator = rcutils_get_default_allocator();
   rcl_params_t * rcl_parameters = rcl_yaml_node_struct_init(allocator);
+  RCPPUTILS_SCOPE_EXIT(rcl_yaml_node_struct_fini(rcl_parameters); );
   const char * path = yaml_filename.c_str();
   if (!rcl_parse_yaml_file(path, rcl_parameters)) {
     rclcpp::exceptions::throw_from_rcl_error(RCL_RET_ERROR);
   }
-  return rclcpp::parameter_map_from(rcl_parameters);
+
+  return rclcpp::parameter_map_from(rcl_parameters, node_fqn);
+}
+
+std::vector<rclcpp::Parameter>
+rclcpp::parameters_from_map(const ParameterMap & parameter_map, const char * node_fqn)
+{
+  std::vector<rclcpp::Parameter> parameters;
+  std::string node_name_old;
+  for (auto & [node_name, node_parameters] : parameter_map) {
+    if (node_fqn && !is_node_name_matched(node_name, node_fqn)) {
+      // No need to parse the items because the user just care about node_fqn
+      continue;
+    }
+    parameters.insert(parameters.end(), node_parameters.begin(), node_parameters.end());
+  }
+
+  return parameters;
 }

rclcpp/src/rclcpp/parameter_service.cpp

@@ -29,7 +29,7 @@ ParameterService::ParameterService(
   const std::shared_ptr<rclcpp::node_interfaces::NodeBaseInterface> node_base,
   const std::shared_ptr<rclcpp::node_interfaces::NodeServicesInterface> node_services,
   rclcpp::node_interfaces::NodeParametersInterface * node_params,
-  const rmw_qos_profile_t & qos_profile)
+  const rclcpp::QoS & qos_profile)
 {
   const std::string node_name = node_base->get_name();
 
@@ -48,6 +48,8 @@ ParameterService::ParameterService(
         }
       } catch (const rclcpp::exceptions::ParameterNotDeclaredException & ex) {
         RCLCPP_DEBUG(rclcpp::get_logger("rclcpp"), "Failed to get parameters: %s", ex.what());
+      } catch (const rclcpp::exceptions::ParameterUninitializedException & ex) {
+        RCLCPP_DEBUG(rclcpp::get_logger("rclcpp"), "Failed to get parameters: %s", ex.what());
       }
     },
     qos_profile, nullptr);

rclcpp/src/rclcpp/publisher_base.cpp

@@ -45,11 +45,14 @@ PublisherBase::PublisherBase(
   rclcpp::node_interfaces::NodeBaseInterface * node_base,
   const std::string & topic,
   const rosidl_message_type_support_t & type_support,
-  const rcl_publisher_options_t & publisher_options)
+  const rcl_publisher_options_t & publisher_options,
+  const PublisherEventCallbacks & event_callbacks,
+  bool use_default_callbacks)
 : rcl_node_handle_(node_base->get_shared_rcl_node_handle()),
   intra_process_is_enabled_(false),
   intra_process_publisher_id_(0),
-  type_support_(type_support)
+  type_support_(type_support),
+  event_callbacks_(event_callbacks)
 {
   auto custom_deleter = [node_handle = this->rcl_node_handle_](rcl_publisher_t * rcl_pub)
     {
@@ -98,15 +101,12 @@ PublisherBase::PublisherBase(
     rmw_reset_error();
     throw std::runtime_error(msg);
   }
+
+  bind_event_callbacks(event_callbacks_, use_default_callbacks);
 }
 
 PublisherBase::~PublisherBase()
 {
-  for (const auto & pair : event_handlers_) {
-    rcl_publisher_event_type_t event_type = pair.first;
-    clear_on_new_qos_event_callback(event_type);
-  }
-
   // must fini the events before fini-ing the publisher
   event_handlers_.clear();
 
@@ -131,6 +131,38 @@ PublisherBase::get_topic_name() const
   return rcl_publisher_get_topic_name(publisher_handle_.get());
 }
 
+void
+PublisherBase::bind_event_callbacks(
+  const PublisherEventCallbacks & event_callbacks, bool use_default_callbacks)
+{
+  if (event_callbacks.deadline_callback) {
+    this->add_event_handler(
+      event_callbacks.deadline_callback,
+      RCL_PUBLISHER_OFFERED_DEADLINE_MISSED);
+  }
+  if (event_callbacks.liveliness_callback) {
+    this->add_event_handler(
+      event_callbacks.liveliness_callback,
+      RCL_PUBLISHER_LIVELINESS_LOST);
+  }
+  if (event_callbacks.incompatible_qos_callback) {
+    this->add_event_handler(
+      event_callbacks.incompatible_qos_callback,
+      RCL_PUBLISHER_OFFERED_INCOMPATIBLE_QOS);
+  } else if (use_default_callbacks) {
+    // Register default callback when not specified
+    try {
+      this->add_event_handler(
+        [this](QOSOfferedIncompatibleQoSInfo & info) {
+          this->default_incompatible_qos_callback(info);
+        },
+        RCL_PUBLISHER_OFFERED_INCOMPATIBLE_QOS);
+    } catch (UnsupportedEventTypeException & /*exc*/) {
+      // pass
+    }
+  }
+}
+
 size_t
 PublisherBase::get_queue_size() const
 {

rclcpp/src/rclcpp/qos.cpp

@@ -16,6 +16,8 @@
 
 #include <string>
 
+#include "rclcpp/logging.hpp"
+
 #include "rmw/error_handling.h"
 #include "rmw/types.h"
 #include "rmw/qos_profiles.h"
@@ -43,9 +45,19 @@ std::string qos_policy_name_from_kind(rmw_qos_policy_kind_t policy_kind)
   }
 }
 
-QoSInitialization::QoSInitialization(rmw_qos_history_policy_t history_policy_arg, size_t depth_arg)
+QoSInitialization::QoSInitialization(
+  rmw_qos_history_policy_t history_policy_arg, size_t depth_arg,
+  bool print_depth_warning)
 : history_policy(history_policy_arg), depth(depth_arg)
-{}
+{
+  if (history_policy == RMW_QOS_POLICY_HISTORY_KEEP_LAST && depth == 0 && print_depth_warning) {
+    RCLCPP_WARN_ONCE(
+      rclcpp::get_logger(
+        "rclcpp"),
+      "A zero depth with KEEP_LAST doesn't make sense; no data could be stored. "
+      "This will be interpreted as SYSTEM_DEFAULT");
+  }
+}
 
 QoSInitialization
 QoSInitialization::from_rmw(const rmw_qos_profile_t & rmw_qos)
@@ -53,8 +65,9 @@ QoSInitialization::from_rmw(const rmw_qos_profile_t & rmw_qos)
   switch (rmw_qos.history) {
     case RMW_QOS_POLICY_HISTORY_KEEP_ALL:
       return KeepAll();
-    case RMW_QOS_POLICY_HISTORY_KEEP_LAST:
     case RMW_QOS_POLICY_HISTORY_SYSTEM_DEFAULT:
+      return KeepLast(rmw_qos.depth, false);
+    case RMW_QOS_POLICY_HISTORY_KEEP_LAST:
     case RMW_QOS_POLICY_HISTORY_UNKNOWN:
     default:
       return KeepLast(rmw_qos.depth);
@@ -65,9 +78,10 @@ KeepAll::KeepAll()
 : QoSInitialization(RMW_QOS_POLICY_HISTORY_KEEP_ALL, 0)
 {}
 
-KeepLast::KeepLast(size_t depth)
-: QoSInitialization(RMW_QOS_POLICY_HISTORY_KEEP_LAST, depth)
-{}
+KeepLast::KeepLast(size_t depth, bool print_depth_warning)
+: QoSInitialization(RMW_QOS_POLICY_HISTORY_KEEP_LAST, depth, print_depth_warning)
+{
+}
 
 QoS::QoS(
   const QoSInitialization & qos_initialization,
@@ -111,6 +125,14 @@ QoS::history(HistoryPolicy history)
 QoS &
 QoS::keep_last(size_t depth)
 {
+  if (depth == 0) {
+    RCLCPP_WARN_ONCE(
+      rclcpp::get_logger(
+        "rclcpp"),
+      "A zero depth with KEEP_LAST doesn't make sense; no data could be stored."
+      "This will be interpreted as SYSTEM_DEFAULT");
+  }
+
   rmw_qos_profile_.history = RMW_QOS_POLICY_HISTORY_KEEP_LAST;
   rmw_qos_profile_.depth = depth;
   return *this;
@@ -150,6 +172,12 @@ QoS::best_effort()
   return this->reliability(RMW_QOS_POLICY_RELIABILITY_BEST_EFFORT);
 }
 
+QoS &
+QoS::reliability_best_available()
+{
+  return this->reliability(RMW_QOS_POLICY_RELIABILITY_BEST_AVAILABLE);
+}
+
 QoS &
 QoS::durability(rmw_qos_durability_policy_t durability)
 {
@@ -176,6 +204,12 @@ QoS::transient_local()
   return this->durability(RMW_QOS_POLICY_DURABILITY_TRANSIENT_LOCAL);
 }
 
+QoS &
+QoS::durability_best_available()
+{
+  return this->durability(RMW_QOS_POLICY_DURABILITY_BEST_AVAILABLE);
+}
+
 QoS &
 QoS::deadline(rmw_time_t deadline)
 {
@@ -380,4 +414,8 @@ SystemDefaultsQoS::SystemDefaultsQoS(const QoSInitialization & qos_initializatio
 : QoS(qos_initialization, rmw_qos_profile_system_default)
 {}
 
+BestAvailableQoS::BestAvailableQoS(const QoSInitialization & qos_initialization)
+: QoS(qos_initialization, rmw_qos_profile_best_available)
+{}
+
 }  // namespace rclcpp

rclcpp/src/rclcpp/qos_event.cpp

@@ -35,9 +35,12 @@ UnsupportedEventTypeException::UnsupportedEventTypeException(
 
 QOSEventHandlerBase::~QOSEventHandlerBase()
 {
-  if (on_new_event_callback_) {
-    clear_on_ready_callback();
-  }
+  // Since the rmw event listener holds a reference to
+  // this callback, we need to clear it on destruction of this class.
+  // This clearing is not needed for other rclcpp entities like pub/subs, since
+  // they do own the underlying rmw entities, which are destroyed
+  // on their rclcpp destructors, thus no risk of dangling pointers.
+  clear_on_ready_callback();
 
   if (rcl_event_fini(&event_handle_) != RCL_RET_OK) {
     RCUTILS_LOG_ERROR_NAMED(

rclcpp/src/rclcpp/service.cpp

@@ -32,10 +32,6 @@ ServiceBase::ServiceBase(std::shared_ptr<rcl_node_t> node_handle)
   node_logger_(rclcpp::get_node_logger(node_handle_.get()))
 {}
 
-ServiceBase::~ServiceBase()
-{
-  clear_on_new_request_callback();
-}
 
 bool
 ServiceBase::take_type_erased_request(void * request_out, rmw_request_id_t & request_id_out)

rclcpp/src/rclcpp/signal_handler.cpp

@@ -191,7 +191,9 @@ SignalHandler::uninstall()
     signal_handlers_options_ = SignalHandlerOptions::None;
     RCLCPP_DEBUG(get_logger(), "SignalHandler::uninstall(): notifying deferred signal handler");
     notify_signal_handler();
-    signal_handler_thread_.join();
+    if (signal_handler_thread_.joinable()) {
+      signal_handler_thread_.join();
+    }
     teardown_wait_for_signal();
   } catch (...) {
     installed_.exchange(true);

rclcpp/src/rclcpp/subscription_base.cpp

@@ -39,12 +39,15 @@ SubscriptionBase::SubscriptionBase(
   const rosidl_message_type_support_t & type_support_handle,
   const std::string & topic_name,
   const rcl_subscription_options_t & subscription_options,
+  const SubscriptionEventCallbacks & event_callbacks,
+  bool use_default_callbacks,
   bool is_serialized)
 : node_base_(node_base),
   node_handle_(node_base_->get_shared_rcl_node_handle()),
   node_logger_(rclcpp::get_node_logger(node_handle_.get())),
   use_intra_process_(false),
   intra_process_subscription_id_(0),
+  event_callbacks_(event_callbacks),
   type_support_(type_support_handle),
   is_serialized_(is_serialized)
 {
@@ -80,20 +83,14 @@ SubscriptionBase::SubscriptionBase(
         rcl_node_get_name(rcl_node_handle),
         rcl_node_get_namespace(rcl_node_handle));
     }
-
     rclcpp::exceptions::throw_from_rcl_error(ret, "could not create subscription");
   }
+
+  bind_event_callbacks(event_callbacks_, use_default_callbacks);
 }
 
 SubscriptionBase::~SubscriptionBase()
 {
-  clear_on_new_message_callback();
-
-  for (const auto & pair : event_handlers_) {
-    rcl_subscription_event_type_t event_type = pair.first;
-    clear_on_new_qos_event_callback(event_type);
-  }
-
   if (!use_intra_process_) {
     return;
   }
@@ -108,6 +105,43 @@ SubscriptionBase::~SubscriptionBase()
   ipm->remove_subscription(intra_process_subscription_id_);
 }
 
+void
+SubscriptionBase::bind_event_callbacks(
+  const SubscriptionEventCallbacks & event_callbacks, bool use_default_callbacks)
+{
+  if (event_callbacks.deadline_callback) {
+    this->add_event_handler(
+      event_callbacks.deadline_callback,
+      RCL_SUBSCRIPTION_REQUESTED_DEADLINE_MISSED);
+  }
+  if (event_callbacks.liveliness_callback) {
+    this->add_event_handler(
+      event_callbacks.liveliness_callback,
+      RCL_SUBSCRIPTION_LIVELINESS_CHANGED);
+  }
+  if (event_callbacks.incompatible_qos_callback) {
+    this->add_event_handler(
+      event_callbacks.incompatible_qos_callback,
+      RCL_SUBSCRIPTION_REQUESTED_INCOMPATIBLE_QOS);
+  } else if (use_default_callbacks) {
+    // Register default callback when not specified
+    try {
+      this->add_event_handler(
+        [this](QOSRequestedIncompatibleQoSInfo & info) {
+          this->default_incompatible_qos_callback(info);
+        },
+        RCL_SUBSCRIPTION_REQUESTED_INCOMPATIBLE_QOS);
+    } catch (UnsupportedEventTypeException & /*exc*/) {
+      // pass
+    }
+  }
+  if (event_callbacks.message_lost_callback) {
+    this->add_event_handler(
+      event_callbacks.message_lost_callback,
+      RCL_SUBSCRIPTION_MESSAGE_LOST);
+  }
+}
+
 const char *
 SubscriptionBase::get_topic_name() const
 {

rclcpp/src/rclcpp/subscription_intra_process_base.cpp

@@ -17,11 +17,6 @@
 
 using rclcpp::experimental::SubscriptionIntraProcessBase;
 
-SubscriptionIntraProcessBase::~SubscriptionIntraProcessBase()
-{
-  clear_on_ready_callback();
-}
-
 void
 SubscriptionIntraProcessBase::add_to_wait_set(rcl_wait_set_t * wait_set)
 {

rclcpp/src/rclcpp/time_source.cpp

@@ -37,7 +37,8 @@ class ClocksState final
 {
 public:
   ClocksState()
-  : logger_(rclcpp::get_logger("rclcpp"))
+  : logger_(rclcpp::get_logger("rclcpp")),
+    last_time_msg_(std::make_shared<builtin_interfaces::msg::Time>())
   {
   }
 
@@ -53,13 +54,8 @@ public:
     ros_time_active_ = true;
 
     // Update all attached clocks to zero or last recorded time
-    std::lock_guard<std::mutex> guard(clock_list_lock_);
-    auto time_msg = std::make_shared<builtin_interfaces::msg::Time>();
-    if (last_msg_set_) {
-      time_msg = std::make_shared<builtin_interfaces::msg::Time>(last_msg_set_->clock);
-    }
     for (auto it = associated_clocks_.begin(); it != associated_clocks_.end(); ++it) {
-      set_clock(time_msg, true, *it);
+      set_clock(last_time_msg_, true, *it);
     }
   }
 
@@ -91,18 +87,17 @@ public:
   // Attach a clock
   void attachClock(rclcpp::Clock::SharedPtr clock)
   {
-    if (clock->get_clock_type() != RCL_ROS_TIME) {
-      throw std::invalid_argument("Cannot attach clock to a time source that's not a ROS clock");
+    {
+      std::lock_guard<std::mutex> clock_guard(clock->get_clock_mutex());
+      if (clock->get_clock_type() != RCL_ROS_TIME && ros_time_active_) {
+        throw std::invalid_argument(
+                "ros_time_active_ can't be true while clock is not of RCL_ROS_TIME type");
+      }
     }
-
     std::lock_guard<std::mutex> guard(clock_list_lock_);
     associated_clocks_.push_back(clock);
     // Set the clock to zero unless there's a recently received message
-    auto time_msg = std::make_shared<builtin_interfaces::msg::Time>();
-    if (last_msg_set_) {
-      time_msg = std::make_shared<builtin_interfaces::msg::Time>(last_msg_set_->clock);
-    }
-    set_clock(time_msg, ros_time_active_, clock);
+    set_clock(last_time_msg_, ros_time_active_, clock);
   }
 
   // Detach a clock
@@ -125,27 +120,32 @@ public:
   {
     std::lock_guard<std::mutex> clock_guard(clock->get_clock_mutex());
 
-    // Do change
-    if (!set_ros_time_enabled && clock->ros_time_is_active()) {
-      auto ret = rcl_disable_ros_time_override(clock->get_clock_handle());
-      if (ret != RCL_RET_OK) {
-        rclcpp::exceptions::throw_from_rcl_error(
-          ret, "Failed to disable ros_time_override_status");
+    if (clock->get_clock_type() == RCL_ROS_TIME) {
+      // Do change
+      if (!set_ros_time_enabled && clock->ros_time_is_active()) {
+        auto ret = rcl_disable_ros_time_override(clock->get_clock_handle());
+        if (ret != RCL_RET_OK) {
+          rclcpp::exceptions::throw_from_rcl_error(
+            ret, "Failed to disable ros_time_override_status");
+        }
+      } else if (set_ros_time_enabled && !clock->ros_time_is_active()) {
+        auto ret = rcl_enable_ros_time_override(clock->get_clock_handle());
+        if (ret != RCL_RET_OK) {
+          rclcpp::exceptions::throw_from_rcl_error(
+            ret, "Failed to enable ros_time_override_status");
+        }
       }
-    } else if (set_ros_time_enabled && !clock->ros_time_is_active()) {
-      auto ret = rcl_enable_ros_time_override(clock->get_clock_handle());
-      if (ret != RCL_RET_OK) {
-        rclcpp::exceptions::throw_from_rcl_error(
-          ret, "Failed to enable ros_time_override_status");
-      }
-    }
 
-    auto ret = rcl_set_ros_time_override(
-      clock->get_clock_handle(),
-      rclcpp::Time(*msg).nanoseconds());
-    if (ret != RCL_RET_OK) {
-      rclcpp::exceptions::throw_from_rcl_error(
-        ret, "Failed to set ros_time_override_status");
+      auto ret = rcl_set_ros_time_override(
+        clock->get_clock_handle(),
+        rclcpp::Time(*msg).nanoseconds());
+      if (ret != RCL_RET_OK) {
+        rclcpp::exceptions::throw_from_rcl_error(
+          ret, "Failed to set ros_time_override_status");
+      }
+    } else if (set_ros_time_enabled) {
+      throw std::invalid_argument(
+              "set_ros_time_enabled can't be true while clock is not of RCL_ROS_TIME type");
     }
   }
 
@@ -163,7 +163,19 @@ public:
   // Cache the last clock message received
   void cache_last_msg(std::shared_ptr<const rosgraph_msgs::msg::Clock> msg)
   {
-    last_msg_set_ = msg;
+    last_time_msg_ = std::make_shared<builtin_interfaces::msg::Time>(msg->clock);
+  }
+
+  bool are_all_clocks_rcl_ros_time()
+  {
+    std::lock_guard<std::mutex> guard(clock_list_lock_);
+    for (auto & clock : associated_clocks_) {
+      std::lock_guard<std::mutex> clock_guard(clock->get_clock_mutex());
+      if (clock->get_clock_type() != RCL_ROS_TIME) {
+        return false;
+      }
+    }
+    return true;
   }
 
 private:
@@ -179,7 +191,7 @@ private:
   // This is needed when new clocks are added.
   bool ros_time_active_{false};
   // Last set message to be passed to newly registered clocks
-  std::shared_ptr<const rosgraph_msgs::msg::Clock> last_msg_set_;
+  std::shared_ptr<builtin_interfaces::msg::Time> last_time_msg_{nullptr};
 };
 
 class TimeSource::NodeState final
@@ -266,6 +278,10 @@ public:
       throw std::invalid_argument("Invalid type for parameter 'use_sim_time', should be 'bool'");
     }
 
+    on_set_parameters_callback_ = node_parameters_->add_on_set_parameters_callback(
+      std::bind(&TimeSource::NodeState::on_set_parameters, this, std::placeholders::_1));
+
+
     // TODO(tfoote) use parameters interface not subscribe to events via topic ticketed #609
     parameter_subscription_ = rclcpp::AsyncParametersClient::on_parameter_event(
       node_topics_,
@@ -285,6 +301,10 @@ public:
     // can't possibly call any of the callbacks as we are cleaning up.
     destroy_clock_sub();
     clocks_state_.disable_ros_time();
+    if (on_set_parameters_callback_) {
+      node_parameters_->remove_on_set_parameters_callback(on_set_parameters_callback_.get());
+    }
+    on_set_parameters_callback_.reset();
     parameter_subscription_.reset();
     node_base_.reset();
     node_topics_.reset();
@@ -419,10 +439,34 @@ private:
     clock_subscription_.reset();
   }
 
+  // On set Parameters callback handle
+  node_interfaces::OnSetParametersCallbackHandle::SharedPtr on_set_parameters_callback_{nullptr};
+
   // Parameter Event subscription
   using ParamSubscriptionT = rclcpp::Subscription<rcl_interfaces::msg::ParameterEvent>;
   std::shared_ptr<ParamSubscriptionT> parameter_subscription_;
 
+  // Callback for parameter settings
+  rcl_interfaces::msg::SetParametersResult on_set_parameters(
+    const std::vector<rclcpp::Parameter> & parameters)
+  {
+    rcl_interfaces::msg::SetParametersResult result;
+    result.successful = true;
+    for (const auto & param : parameters) {
+      if (param.get_name() == "use_sim_time" && param.get_type() == rclcpp::PARAMETER_BOOL) {
+        if (param.as_bool() && !(clocks_state_.are_all_clocks_rcl_ros_time())) {
+          result.successful = false;
+          result.reason =
+            "use_sim_time parameter can't be true while clocks are not all of RCL_ROS_TIME type";
+          RCLCPP_ERROR(
+            logger_,
+            "use_sim_time parameter can't be true while clocks are not all of RCL_ROS_TIME type");
+        }
+      }
+    }
+    return result;
+  }
+
   // Callback for parameter updates
   void on_parameter_event(std::shared_ptr<const rcl_interfaces::msg::ParameterEvent> event)
   {

rclcpp/src/rclcpp/timer.cpp

@@ -19,9 +19,12 @@
 #include <memory>
 #include <thread>
 
-#include "rclcpp/contexts/default_context.hpp"
-#include "rclcpp/exceptions.hpp"
+#include "rmw/impl/cpp/demangle.hpp"
 
+#include "rclcpp/contexts/default_context.hpp"
+#include "rclcpp/detail/cpp_callback_trampoline.hpp"
+#include "rclcpp/exceptions.hpp"
+#include "rclcpp/logging.hpp"
 #include "rcutils/logging_macros.h"
 
 using rclcpp::TimerBase;
@@ -71,7 +74,9 @@ TimerBase::TimerBase(
 }
 
 TimerBase::~TimerBase()
-{}
+{
+  clear_on_reset_callback();
+}
 
 void
 TimerBase::cancel()
@@ -96,7 +101,11 @@ TimerBase::is_canceled()
 void
 TimerBase::reset()
 {
-  rcl_ret_t ret = rcl_timer_reset(timer_handle_.get());
+  rcl_ret_t ret = RCL_RET_OK;
+  {
+    std::lock_guard<std::recursive_mutex> lock(callback_mutex_);
+    ret = rcl_timer_reset(timer_handle_.get());
+  }
   if (ret != RCL_RET_OK) {
     rclcpp::exceptions::throw_from_rcl_error(ret, "Couldn't reset timer");
   }
@@ -138,3 +147,73 @@ TimerBase::exchange_in_use_by_wait_set_state(bool in_use_state)
 {
   return in_use_by_wait_set_.exchange(in_use_state);
 }
+
+void
+TimerBase::set_on_reset_callback(std::function<void(size_t)> callback)
+{
+  if (!callback) {
+    throw std::invalid_argument(
+            "The callback passed to set_on_reset_callback "
+            "is not callable.");
+  }
+
+  auto new_callback =
+    [callback, this](size_t reset_calls) {
+      try {
+        callback(reset_calls);
+      } catch (const std::exception & exception) {
+        RCLCPP_ERROR_STREAM(
+          rclcpp::get_logger("rclcpp"),
+          "rclcpp::TimerBase@" << this <<
+            " caught " << rmw::impl::cpp::demangle(exception) <<
+            " exception in user-provided callback for the 'on reset' callback: " <<
+            exception.what());
+      } catch (...) {
+        RCLCPP_ERROR_STREAM(
+          rclcpp::get_logger("rclcpp"),
+          "rclcpp::TimerBase@" << this <<
+            " caught unhandled exception in user-provided callback " <<
+            "for the 'on reset' callback");
+      }
+    };
+
+  std::lock_guard<std::recursive_mutex> lock(callback_mutex_);
+
+  // Set it temporarily to the new callback, while we replace the old one.
+  // This two-step setting, prevents a gap where the old std::function has
+  // been replaced but rcl hasn't been told about the new one yet.
+  set_on_reset_callback(
+    rclcpp::detail::cpp_callback_trampoline<
+      decltype(new_callback), const void *, size_t>,
+    static_cast<const void *>(&new_callback));
+
+  // Store the std::function to keep it in scope, also overwrites the existing one.
+  on_reset_callback_ = new_callback;
+
+  // Set it again, now using the permanent storage.
+  set_on_reset_callback(
+    rclcpp::detail::cpp_callback_trampoline<
+      decltype(on_reset_callback_), const void *, size_t>,
+    static_cast<const void *>(&on_reset_callback_));
+}
+
+void
+TimerBase::clear_on_reset_callback()
+{
+  std::lock_guard<std::recursive_mutex> lock(callback_mutex_);
+
+  if (on_reset_callback_) {
+    set_on_reset_callback(nullptr, nullptr);
+    on_reset_callback_ = nullptr;
+  }
+}
+
+void
+TimerBase::set_on_reset_callback(rcl_event_callback_t callback, const void * user_data)
+{
+  rcl_ret_t ret = rcl_timer_set_on_reset_callback(timer_handle_.get(), callback, user_data);
+
+  if (ret != RCL_RET_OK) {
+    rclcpp::exceptions::throw_from_rcl_error(ret, "Failed to set timer on reset callback");
+  }
+}