Make get_rcl_allocator a function family

As explained in #1254, there's conceptually no way to implement RCL
allocators in terms of C++ allocators. In order to fix this behavior,
we have to delete the generic version of get_rcl_allocator. Since some
ROS code depends on this, we need to allow users to write their own
version of get_rcl_allocator for allocators that support the C-style
interface (most do).

So this CL changes get_rcl_allocator from a template function
into a family of (potentially templated) functions, which allows
users to add their own overloads and rely on the "most specialized"
mechanism for function specialization to select the right one. See
http://www.gotw.ca/publications/mill17.htm for details. This also
allows us to return get_rcl_default_allocator for all specializations
of std::allocator (previously, only for std::allocator), which will
already fix #1254 for pretty much all clients. I'll continue to work
on deleting the generic version, though, to make sure that nobody is
accidentally bitten by it.

I've tried to test this by doing a full ROS compilation following the
Dockerfile of the source Docker image, and all packages compile.

Signed-off-by: Steve Wolter <swolter@google.com>

README.md

@@ -12,6 +12,6 @@ Visit the [rclcpp API documentation](http://docs.ros2.org/latest/api/rclcpp/) fo
 
 ### Examples
 
-The ROS 2 tutorials [Writing a simple publisher and subscriber](https://index.ros.org/doc/ros2/Tutorials/Writing-A-Simple-Cpp-Publisher-And-Subscriber/)
-and [Writing a simple service and client](https://index.ros.org/doc/ros2/Tutorials/Writing-A-Simple-Cpp-Service-And-Client/)
+The ROS 2 tutorials [Writing a simple publisher and subscriber](https://docs.ros.org/en/rolling/Tutorials/Writing-A-Simple-Cpp-Publisher-And-Subscriber.html).
+and [Writing a simple service and client](https://docs.ros.org/en/rolling/Tutorials/Writing-A-Simple-Cpp-Service-And-Client.html)
 contain some examples of rclcpp APIs in use.

rclcpp/CHANGELOG.rst

@@ -2,6 +2,211 @@
 Changelog for package rclcpp
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+9.0.2 (2021-04-14)
+------------------
+* Avoid returning loan when none was obtained. (`#1629 <https://github.com/ros2/rclcpp/issues/1629>`_)
+* Use a different implementation of mutex two priorities (`#1628 <https://github.com/ros2/rclcpp/issues/1628>`_)
+* Do not test the value of the history policy when testing the get_publishers/subscriptions_info_by_topic() methods (`#1626 <https://github.com/ros2/rclcpp/issues/1626>`_)
+* Check first parameter type and range before calling the user validation callbacks (`#1627 <https://github.com/ros2/rclcpp/issues/1627>`_)
+* Contributors: Ivan Santiago Paunovic, Miguel Company
+
+9.0.1 (2021-04-12)
+------------------
+* Restore test exception for Connext (`#1625 <https://github.com/ros2/rclcpp/issues/1625>`_)
+* Fix race condition in TimeSource clock thread setup (`#1623 <https://github.com/ros2/rclcpp/issues/1623>`_)
+* Contributors: Andrea Sorbini, Michel Hidalgo
+
+9.0.0 (2021-04-06)
+------------------
+* remove deprecated code which was deprecated in foxy and should be removed in galactic (`#1622 <https://github.com/ros2/rclcpp/issues/1622>`_)
+* Change index.ros.org -> docs.ros.org. (`#1620 <https://github.com/ros2/rclcpp/issues/1620>`_)
+* Unique network flows (`#1496 <https://github.com/ros2/rclcpp/issues/1496>`_)
+* Add spin_some support to the StaticSingleThreadedExecutor (`#1338 <https://github.com/ros2/rclcpp/issues/1338>`_)
+* Add publishing instrumentation (`#1600 <https://github.com/ros2/rclcpp/issues/1600>`_)
+* Create load_parameters and delete_parameters methods (`#1596 <https://github.com/ros2/rclcpp/issues/1596>`_)
+* refactor AnySubscriptionCallback and add/deprecate callback signatures (`#1598 <https://github.com/ros2/rclcpp/issues/1598>`_)
+* Add generic publisher and generic subscription for serialized messages (`#1452 <https://github.com/ros2/rclcpp/issues/1452>`_)
+* use context from `node_base\_` for clock executor. (`#1617 <https://github.com/ros2/rclcpp/issues/1617>`_)
+* updating quality declaration links (re: `ros2/docs.ros2.org#52 <https://github.com/ros2/docs.ros2.org/issues/52>`_) (`#1615 <https://github.com/ros2/rclcpp/issues/1615>`_)
+* Contributors: Ananya Muddukrishna, BriceRenaudeau, Chris Lalancette, Christophe Bedard, Nikolai Morin, Tomoya Fujita, William Woodall, mauropasse, shonigmann
+
+8.2.0 (2021-03-31)
+------------------
+* Initialize integers in test_parameter_event_handler.cpp to avoid undefined behavior (`#1609 <https://github.com/ros2/rclcpp/issues/1609>`_)
+* Namespace tracetools C++ functions (`#1608 <https://github.com/ros2/rclcpp/issues/1608>`_)
+* Revert "Namespace tracetools C++ functions (`#1603 <https://github.com/ros2/rclcpp/issues/1603>`_)" (`#1607 <https://github.com/ros2/rclcpp/issues/1607>`_)
+* Namespace tracetools C++ functions (`#1603 <https://github.com/ros2/rclcpp/issues/1603>`_)
+* Clock subscription callback group spins in its own thread (`#1556 <https://github.com/ros2/rclcpp/issues/1556>`_)
+* Contributors: Chris Lalancette, Christophe Bedard, Ivan Santiago Paunovic, anaelle-sw
+
+8.1.0 (2021-03-25)
+------------------
+* Remove rmw_connext_cpp references. (`#1595 <https://github.com/ros2/rclcpp/issues/1595>`_)
+* Add API for checking QoS profile compatibility (`#1554 <https://github.com/ros2/rclcpp/issues/1554>`_)
+* Document misuse of parameters callback (`#1590 <https://github.com/ros2/rclcpp/issues/1590>`_)
+* use const auto & to iterate over parameters (`#1593 <https://github.com/ros2/rclcpp/issues/1593>`_)
+* Contributors: Chris Lalancette, Jacob Perron, Karsten Knese
+
+8.0.0 (2021-03-23)
+------------------
+* Guard against integer overflow in duration conversion (`#1584 <https://github.com/ros2/rclcpp/issues/1584>`_)
+* Contributors: Jacob Perron
+
+7.0.1 (2021-03-22)
+------------------
+* get_parameters service should return empty if undeclared parameters are allowed (`#1514 <https://github.com/ros2/rclcpp/issues/1514>`_)
+* Made 'Context::shutdown_reason' function a const function (`#1578 <https://github.com/ros2/rclcpp/issues/1578>`_)
+* Contributors: Tomoya Fujita, suab321321
+
+7.0.0 (2021-03-18)
+------------------
+* Document design decisions that were made for statically typed parameters (`#1568 <https://github.com/ros2/rclcpp/issues/1568>`_)
+* Fix doc typo in CallbackGroup constructor (`#1582 <https://github.com/ros2/rclcpp/issues/1582>`_)
+* Enable qos parameter overrides for the /parameter_events topic  (`#1532 <https://github.com/ros2/rclcpp/issues/1532>`_)
+* Add support for rmw_connextdds (`#1574 <https://github.com/ros2/rclcpp/issues/1574>`_)
+* Remove 'struct' from the rcl_time_jump_t. (`#1577 <https://github.com/ros2/rclcpp/issues/1577>`_)
+* Add tests for declaring statically typed parameters when undeclared parameters are allowed (`#1575 <https://github.com/ros2/rclcpp/issues/1575>`_)
+* Quiet clang memory leak warning on "DoNotOptimize". (`#1571 <https://github.com/ros2/rclcpp/issues/1571>`_)
+* Add ParameterEventsSubscriber class (`#829 <https://github.com/ros2/rclcpp/issues/829>`_)
+* When a parameter change is rejected, the parameters map shouldn't be updated. (`#1567 <https://github.com/ros2/rclcpp/pull/1567>`_)
+* Fix when to throw the NoParameterOverrideProvided exception. (`#1567 <https://github.com/ros2/rclcpp/pull/1567>`_)
+* Fix SEGV caused by order of destruction of Node sub-interfaces (`#1469 <https://github.com/ros2/rclcpp/issues/1469>`_)
+* Fix benchmark test failure introduced in `#1522 <https://github.com/ros2/rclcpp/issues/1522>`_ (`#1564 <https://github.com/ros2/rclcpp/issues/1564>`_)
+* Fix documented example in create_publisher (`#1558 <https://github.com/ros2/rclcpp/issues/1558>`_)
+* Enforce static parameter types (`#1522 <https://github.com/ros2/rclcpp/issues/1522>`_)
+* Allow timers to keep up the intended rate in MultiThreadedExecutor (`#1516 <https://github.com/ros2/rclcpp/issues/1516>`_)
+* Fix UBSAN warnings in any_subscription_callback. (`#1551 <https://github.com/ros2/rclcpp/issues/1551>`_)
+* Fix runtime error: reference binding to null pointer of type (`#1547 <https://github.com/ros2/rclcpp/issues/1547>`_)
+* Contributors: Andrea Sorbini, Chris Lalancette, Colin MacKenzie, Ivan Santiago Paunovic, Jacob Perron, Steven! Ragnarök, bpwilcox, tomoya
+
+6.3.1 (2021-02-08)
+------------------
+* Reference test resources directly from source tree (`#1543 <https://github.com/ros2/rclcpp/issues/1543>`_)
+* clear statistics after window reset (`#1531 <https://github.com/ros2/rclcpp/issues/1531>`_) (`#1535 <https://github.com/ros2/rclcpp/issues/1535>`_)
+* Fix a minor string error in the topic_statistics test. (`#1541 <https://github.com/ros2/rclcpp/issues/1541>`_)
+* Avoid `Resource deadlock avoided` if use intra_process_comms (`#1530 <https://github.com/ros2/rclcpp/issues/1530>`_)
+* Avoid an object copy in parameter_value.cpp. (`#1538 <https://github.com/ros2/rclcpp/issues/1538>`_)
+* Assert that the publisher_list size is 1. (`#1537 <https://github.com/ros2/rclcpp/issues/1537>`_)
+* Don't access objects after they have been std::move (`#1536 <https://github.com/ros2/rclcpp/issues/1536>`_)
+* Update for checking correct variable (`#1534 <https://github.com/ros2/rclcpp/issues/1534>`_)
+* Destroy msg extracted from LoanedMessage. (`#1305 <https://github.com/ros2/rclcpp/issues/1305>`_)
+* Contributors: Chen Lihui, Chris Lalancette, Ivan Santiago Paunovic, Miaofei Mei, Scott K Logan, William Woodall, hsgwa
+
+6.3.0 (2021-01-25)
+------------------
+* Add instrumentation for linking a timer to a node (`#1500 <https://github.com/ros2/rclcpp/issues/1500>`_)
+* Fix error when using IPC with StaticSingleThreadExecutor (`#1520 <https://github.com/ros2/rclcpp/issues/1520>`_)
+* Change to using unique_ptrs for DummyExecutor. (`#1517 <https://github.com/ros2/rclcpp/issues/1517>`_)
+* Allow reconfiguring 'clock' topic qos (`#1512 <https://github.com/ros2/rclcpp/issues/1512>`_)
+* Allow to add/remove nodes thread safely in rclcpp::Executor  (`#1505 <https://github.com/ros2/rclcpp/issues/1505>`_)
+* Call rclcpp::shutdown in test_node for clean shutdown on Windows (`#1515 <https://github.com/ros2/rclcpp/issues/1515>`_)
+* Reapply "Add get_logging_directory method to rclcpp::Logger (`#1509 <https://github.com/ros2/rclcpp/issues/1509>`_)" (`#1513 <https://github.com/ros2/rclcpp/issues/1513>`_)
+* use describe_parameters of parameter client for test (`#1499 <https://github.com/ros2/rclcpp/issues/1499>`_)
+* Revert "Add get_logging_directory method to rclcpp::Logger (`#1509 <https://github.com/ros2/rclcpp/issues/1509>`_)" (`#1511 <https://github.com/ros2/rclcpp/issues/1511>`_)
+* Add get_logging_directory method to rclcpp::Logger (`#1509 <https://github.com/ros2/rclcpp/issues/1509>`_)
+* Contributors: Chris Lalancette, Christophe Bedard, Ivan Santiago Paunovic, eboasson, mauropasse, tomoya
+
+6.2.0 (2021-01-08)
+------------------
+* Better documentation for the QoS class (`#1508 <https://github.com/ros2/rclcpp/issues/1508>`_)
+* Modify excluding callback duration from topic statistics (`#1492 <https://github.com/ros2/rclcpp/issues/1492>`_)
+* Make the test of graph users more robust. (`#1504 <https://github.com/ros2/rclcpp/issues/1504>`_)
+* Make sure to wait for graph change events in test_node_graph. (`#1503 <https://github.com/ros2/rclcpp/issues/1503>`_)
+* add timeout to SyncParametersClient methods (`#1493 <https://github.com/ros2/rclcpp/issues/1493>`_)
+* Fix wrong test expectations (`#1497 <https://github.com/ros2/rclcpp/issues/1497>`_)
+* Update create_publisher/subscription documentation, clarifying when a parameters interface is required (`#1494 <https://github.com/ros2/rclcpp/issues/1494>`_)
+* Fix string literal warnings (`#1442 <https://github.com/ros2/rclcpp/issues/1442>`_)
+* support describe_parameters methods to parameter client. (`#1453 <https://github.com/ros2/rclcpp/issues/1453>`_)
+* Contributors: Audrow Nash, Chris Lalancette, Ivan Santiago Paunovic, Nikolai Morin, hsgwa, tomoya
+
+6.1.0 (2020-12-10)
+------------------
+* Add getters to rclcpp::qos and rclcpp::Policy enum classes (`#1467 <https://github.com/ros2/rclcpp/issues/1467>`_)
+* Change nullptr checks to use ASSERT_TRUE. (`#1486 <https://github.com/ros2/rclcpp/issues/1486>`_)
+* Adjust logic around finding and erasing guard_condition (`#1474 <https://github.com/ros2/rclcpp/issues/1474>`_)
+* Update QDs to QL 1 (`#1477 <https://github.com/ros2/rclcpp/issues/1477>`_)
+* Add performance tests for parameter transport (`#1463 <https://github.com/ros2/rclcpp/issues/1463>`_)
+* Contributors: Chris Lalancette, Ivan Santiago Paunovic, Scott K Logan, Stephen Brawner
+
+6.0.0 (2020-11-18)
+------------------
+* Move ownership of shutdown_guard_condition to executors/graph_listener (`#1404 <https://github.com/ros2/rclcpp/issues/1404>`_)
+* Add options to automatically declare qos parameters when creating a publisher/subscription (`#1465 <https://github.com/ros2/rclcpp/issues/1465>`_)
+* Add `take_data` to `Waitable` and `data` to `AnyExecutable` (`#1241 <https://github.com/ros2/rclcpp/issues/1241>`_)
+* Add benchmarks for node parameters interface (`#1444 <https://github.com/ros2/rclcpp/issues/1444>`_)
+* Remove allocation from executor::remove_node() (`#1448 <https://github.com/ros2/rclcpp/issues/1448>`_)
+* Fix test crashes on CentOS 7 (`#1449 <https://github.com/ros2/rclcpp/issues/1449>`_)
+* Bump rclcpp packages to Quality Level 2 (`#1445 <https://github.com/ros2/rclcpp/issues/1445>`_)
+* Added executor benchmark tests (`#1413 <https://github.com/ros2/rclcpp/issues/1413>`_)
+* Add fully-qualified namespace to WeakCallbackGroupsToNodesMap (`#1435 <https://github.com/ros2/rclcpp/issues/1435>`_)
+* Contributors: Alejandro Hernández Cordero, Audrow Nash, Chris Lalancette, Ivan Santiago Paunovic, Louise Poubel, Scott K Logan, brawner
+
+5.1.0 (2020-11-02)
+------------------
+* Deprecate Duration(rcl_duration_value_t) in favor of static Duration::from_nanoseconds(rcl_duration_value_t) (`#1432 <https://github.com/ros2/rclcpp/issues/1432>`_)
+* Avoid parsing arguments twice in `rclcpp::init_and_remove_ros_arguments` (`#1415 <https://github.com/ros2/rclcpp/issues/1415>`_)
+* Add service and client benchmarks (`#1425 <https://github.com/ros2/rclcpp/issues/1425>`_)
+* Set CMakeLists to only use default rmw for benchmarks (`#1427 <https://github.com/ros2/rclcpp/issues/1427>`_)
+* Update tracetools' QL in rclcpp's QD (`#1428 <https://github.com/ros2/rclcpp/issues/1428>`_)
+* Add missing locking to the rclcpp_action::ServerBase. (`#1421 <https://github.com/ros2/rclcpp/issues/1421>`_)
+* Initial benchmark tests for rclcpp::init/shutdown create/destroy node (`#1411 <https://github.com/ros2/rclcpp/issues/1411>`_)
+* Refactor test CMakeLists in prep for benchmarks (`#1422 <https://github.com/ros2/rclcpp/issues/1422>`_)
+* Add methods in topic and service interface to resolve a name (`#1410 <https://github.com/ros2/rclcpp/issues/1410>`_)
+* Update deprecated gtest macros (`#1370 <https://github.com/ros2/rclcpp/issues/1370>`_)
+* Clear members for StaticExecutorEntitiesCollector to avoid shared_ptr dependency (`#1303 <https://github.com/ros2/rclcpp/issues/1303>`_)
+* Increase test timeouts of slow running tests with rmw_connext_cpp (`#1400 <https://github.com/ros2/rclcpp/issues/1400>`_)
+* Avoid self dependency that not destoryed (`#1301 <https://github.com/ros2/rclcpp/issues/1301>`_)
+* Update maintainers (`#1384 <https://github.com/ros2/rclcpp/issues/1384>`_)
+* Add clock qos to node options (`#1375 <https://github.com/ros2/rclcpp/issues/1375>`_)
+* Fix NodeOptions copy constructor (`#1376 <https://github.com/ros2/rclcpp/issues/1376>`_)
+* Make sure to clean the external client/service handle. (`#1296 <https://github.com/ros2/rclcpp/issues/1296>`_)
+* Increase coverage of WaitSetTemplate (`#1368 <https://github.com/ros2/rclcpp/issues/1368>`_)
+* Increase coverage of guard_condition.cpp to 100% (`#1369 <https://github.com/ros2/rclcpp/issues/1369>`_)
+* Add coverage statement (`#1367 <https://github.com/ros2/rclcpp/issues/1367>`_)
+* Tests for LoanedMessage with mocked loaned message publisher (`#1366 <https://github.com/ros2/rclcpp/issues/1366>`_)
+* Add unit tests for qos and qos_event files (`#1352 <https://github.com/ros2/rclcpp/issues/1352>`_)
+* Finish coverage of publisher API (`#1365 <https://github.com/ros2/rclcpp/issues/1365>`_)
+* Finish API coverage on executors. (`#1364 <https://github.com/ros2/rclcpp/issues/1364>`_)
+* Add test for ParameterService (`#1355 <https://github.com/ros2/rclcpp/issues/1355>`_)
+* Add time API coverage tests (`#1347 <https://github.com/ros2/rclcpp/issues/1347>`_)
+* Add timer coverage tests (`#1363 <https://github.com/ros2/rclcpp/issues/1363>`_)
+* Add in additional tests for parameter_client.cpp coverage.
+* Minor fixes to the parameter_service.cpp file.
+* reset rcl_context shared_ptr after calling rcl_init sucessfully (`#1357 <https://github.com/ros2/rclcpp/issues/1357>`_)
+* Improved test publisher - zero qos history depth value exception (`#1360 <https://github.com/ros2/rclcpp/issues/1360>`_)
+* Covered resolve_use_intra_process (`#1359 <https://github.com/ros2/rclcpp/issues/1359>`_)
+* Improve test_subscription_options (`#1358 <https://github.com/ros2/rclcpp/issues/1358>`_)
+* Add in more tests for init_options coverage. (`#1353 <https://github.com/ros2/rclcpp/issues/1353>`_)
+* Test the remaining node public API (`#1342 <https://github.com/ros2/rclcpp/issues/1342>`_)
+* Complete coverage of Parameter and ParameterValue API (`#1344 <https://github.com/ros2/rclcpp/issues/1344>`_)
+* Add in more tests for the utilities. (`#1349 <https://github.com/ros2/rclcpp/issues/1349>`_)
+* Add in two more tests for expand_topic_or_service_name. (`#1350 <https://github.com/ros2/rclcpp/issues/1350>`_)
+* Add tests for node_options API (`#1343 <https://github.com/ros2/rclcpp/issues/1343>`_)
+* Add in more coverage for expand_topic_or_service_name. (`#1346 <https://github.com/ros2/rclcpp/issues/1346>`_)
+* Test exception in spin_until_future_complete. (`#1345 <https://github.com/ros2/rclcpp/issues/1345>`_)
+* Add coverage tests graph_listener (`#1330 <https://github.com/ros2/rclcpp/issues/1330>`_)
+* Add in unit tests for the Executor class.
+* Allow mimick patching of methods with up to 9 arguments.
+* Improve the error messages in the Executor class.
+* Add coverage for client API (`#1329 <https://github.com/ros2/rclcpp/issues/1329>`_)
+* Increase service coverage (`#1332 <https://github.com/ros2/rclcpp/issues/1332>`_)
+* Make more of the static entity collector API private.
+* Const-ify more of the static executor.
+* Add more tests for the static single threaded executor.
+* Many more tests for the static_executor_entities_collector.
+* Get one more line of code coverage in memory_strategy.cpp
+* Bugfix when adding callback group.
+* Fix typos in comments.
+* Remove deprecated executor::FutureReturnCode APIs. (`#1327 <https://github.com/ros2/rclcpp/issues/1327>`_)
+* Increase coverage of publisher/subscription API (`#1325 <https://github.com/ros2/rclcpp/issues/1325>`_)
+* Not finalize guard condition while destructing SubscriptionIntraProcess (`#1307 <https://github.com/ros2/rclcpp/issues/1307>`_)
+* Expose qos setting for /rosout (`#1247 <https://github.com/ros2/rclcpp/issues/1247>`_)
+* Add coverage for missing API (except executors) (`#1326 <https://github.com/ros2/rclcpp/issues/1326>`_)
+* Include topic name in QoS mismatch warning messages (`#1286 <https://github.com/ros2/rclcpp/issues/1286>`_)
+* Add coverage tests context functions (`#1321 <https://github.com/ros2/rclcpp/issues/1321>`_)
+* Increase coverage of node_interfaces, including with mocking rcl errors (`#1322 <https://github.com/ros2/rclcpp/issues/1322>`_)
+* Contributors: Ada-King, Alejandro Hernández Cordero, Audrow Nash, Barry Xu, Chen Lihui, Chris Lalancette, Christophe Bedard, Ivan Santiago Paunovic, Jorge Perez, Morgan Quigley, brawner
+
 5.0.0 (2020-09-18)
 ------------------
 * Make node_graph::count_graph_users() const (`#1320 <https://github.com/ros2/rclcpp/issues/1320>`_)

rclcpp/CMakeLists.txt

@@ -5,6 +5,7 @@ project(rclcpp)
 find_package(Threads REQUIRED)
 
 find_package(ament_cmake_ros REQUIRED)
+find_package(ament_index_cpp REQUIRED)
 find_package(builtin_interfaces REQUIRED)
 find_package(libstatistics_collector REQUIRED)
 find_package(rcl REQUIRED)
@@ -20,9 +21,10 @@ find_package(rosidl_typesupport_cpp REQUIRED)
 find_package(statistics_msgs REQUIRED)
 find_package(tracetools REQUIRED)
 
-# Default to C++14
+# TODO(wjwwood): remove this when gtest can build on its own, when using target_compile_features()
+# Default to C++17
 if(NOT CMAKE_CXX_STANDARD)
-  set(CMAKE_CXX_STANDARD 14)
+  set(CMAKE_CXX_STANDARD 17)
 endif()
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   # About -Wno-sign-conversion: With Clang, -Wconversion implies -Wsign-conversion. There are a number of
@@ -39,6 +41,8 @@ set(${PROJECT_NAME}_SRCS
   src/rclcpp/clock.cpp
   src/rclcpp/context.cpp
   src/rclcpp/contexts/default_context.cpp
+  src/rclcpp/detail/mutex_two_priorities.cpp
+  src/rclcpp/detail/resolve_parameter_overrides.cpp
   src/rclcpp/detail/rmw_implementation_specific_payload.cpp
   src/rclcpp/detail/rmw_implementation_specific_publisher_payload.cpp
   src/rclcpp/detail/rmw_implementation_specific_subscription_payload.cpp
@@ -49,12 +53,14 @@ set(${PROJECT_NAME}_SRCS
   src/rclcpp/executable_list.cpp
   src/rclcpp/executor.cpp
   src/rclcpp/executors.cpp
-  src/rclcpp/expand_topic_or_service_name.cpp
   src/rclcpp/executors/multi_threaded_executor.cpp
   src/rclcpp/executors/single_threaded_executor.cpp
   src/rclcpp/executors/static_executor_entities_collector.cpp
   src/rclcpp/executors/static_single_threaded_executor.cpp
+  src/rclcpp/expand_topic_or_service_name.cpp
   src/rclcpp/future_return_code.cpp
+  src/rclcpp/generic_publisher.cpp
+  src/rclcpp/generic_subscription.cpp
   src/rclcpp/graph_listener.cpp
   src/rclcpp/guard_condition.cpp
   src/rclcpp/init_options.cpp
@@ -64,8 +70,8 @@ set(${PROJECT_NAME}_SRCS
   src/rclcpp/memory_strategies.cpp
   src/rclcpp/memory_strategy.cpp
   src/rclcpp/message_info.cpp
+  src/rclcpp/network_flow_endpoint.cpp
   src/rclcpp/node.cpp
-  src/rclcpp/node_options.cpp
   src/rclcpp/node_interfaces/node_base.cpp
   src/rclcpp/node_interfaces/node_clock.cpp
   src/rclcpp/node_interfaces/node_graph.cpp
@@ -76,15 +82,18 @@ set(${PROJECT_NAME}_SRCS
   src/rclcpp/node_interfaces/node_timers.cpp
   src/rclcpp/node_interfaces/node_topics.cpp
   src/rclcpp/node_interfaces/node_waitables.cpp
+  src/rclcpp/node_options.cpp
   src/rclcpp/parameter.cpp
-  src/rclcpp/parameter_value.cpp
   src/rclcpp/parameter_client.cpp
+  src/rclcpp/parameter_event_handler.cpp
   src/rclcpp/parameter_events_filter.cpp
   src/rclcpp/parameter_map.cpp
   src/rclcpp/parameter_service.cpp
+  src/rclcpp/parameter_value.cpp
   src/rclcpp/publisher_base.cpp
   src/rclcpp/qos.cpp
   src/rclcpp/qos_event.cpp
+  src/rclcpp/qos_overriding_options.cpp
   src/rclcpp/serialization.cpp
   src/rclcpp/serialized_message.cpp
   src/rclcpp/service.cpp
@@ -95,6 +104,7 @@ set(${PROJECT_NAME}_SRCS
   src/rclcpp/time_source.cpp
   src/rclcpp/timer.cpp
   src/rclcpp/type_support.cpp
+  src/rclcpp/typesupport_helpers.cpp
   src/rclcpp/utilities.cpp
   src/rclcpp/wait_set_policies/detail/write_preferring_read_write_lock.cpp
   src/rclcpp/waitable.cpp
@@ -166,8 +176,12 @@ foreach(interface_file ${interface_files})
     include/rclcpp/node_interfaces/get_${interface_name}.hpp)
 endforeach()
 
-add_library(${PROJECT_NAME}
-  ${${PROJECT_NAME}_SRCS})
+add_library(${PROJECT_NAME} ${${PROJECT_NAME}_SRCS})
+target_compile_features(${PROJECT_NAME} PUBLIC cxx_std_17)
+# TODO(wjwwood): address all deprecation warnings and then remove this
+if(WIN32)
+  target_compile_definitions(${PROJECT_NAME} PUBLIC "_SILENCE_ALL_CXX17_DEPRECATION_WARNINGS")
+endif()
 target_include_directories(${PROJECT_NAME} PUBLIC
   "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>"
   "$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include>"
@@ -175,6 +189,7 @@ target_include_directories(${PROJECT_NAME} PUBLIC
 target_link_libraries(${PROJECT_NAME} ${CMAKE_THREAD_LIBS_INIT})
 # specific order: dependents before dependencies
 ament_target_dependencies(${PROJECT_NAME}
+  "ament_index_cpp"
   "libstatistics_collector"
   "rcl"
   "rcl_yaml_param_parser"
@@ -205,6 +220,7 @@ ament_export_include_directories(include)
 ament_export_libraries(${PROJECT_NAME})
 ament_export_targets(${PROJECT_NAME})
 
+ament_export_dependencies(ament_index_cpp)
 ament_export_dependencies(libstatistics_collector)
 ament_export_dependencies(rcl)
 ament_export_dependencies(rcpputils)
@@ -231,3 +247,8 @@ install(
   DIRECTORY include/ ${CMAKE_CURRENT_BINARY_DIR}/include/
   DESTINATION include
 )
+
+if(TEST cppcheck)
+  # must set the property after ament_package()
+  set_tests_properties(cppcheck PROPERTIES TIMEOUT 500)
+endif()

rclcpp/QUALITY_DECLARATION.md

@@ -2,15 +2,15 @@ This document is a declaration of software quality for the `rclcpp` package, bas
 
 # rclcpp Quality Declaration
 
-The package `rclcpp` claims to be in the **Quality Level 3** category.
+The package `rclcpp` claims to be in the **Quality Level 1** category when it is used with a **Quality Level 1** middleware.
 
-Below are the rationales, notes, and caveats for this claim, organized by each requirement listed in the [Package Quality Categories in REP-2004](https://index.ros.org/doc/ros2/Contributing/Developer-Guide/#package-quality-categories) of the ROS2 developer guide.
+Below are the rationales, notes, and caveats for this claim, organized by each requirement listed in the [Package Quality Categories in REP-2004](https://www.ros.org/reps/rep-2004.html) of the ROS2 developer guide.
 
 ## Version Policy [1]
 
 ### Version Scheme [1.i]
 
-`rclcpp` uses `semver` according to the recommendation for ROS Core packages in the [ROS 2 Developer Guide](https://index.ros.org/doc/ros2/Contributing/Developer-Guide/#versioning).
+`rclcpp` uses `semver` according to the recommendation for ROS Core packages in the [ROS 2 Developer Guide](https://docs.ros.org/en/rolling/Contributing/Developer-Guide.html#versioning).
 
 ### Version Stability [1.ii]
 
@@ -39,11 +39,11 @@ Headers under the folder `detail` are not considered part of the public API and
 
 ## Change Control Process [2]
 
-`rclcpp` follows the recommended guidelines for ROS Core packages in the [ROS 2 Developer Guide](https://index.ros.org/doc/ros2/Contributing/Developer-Guide/#change-control-process).
+`rclcpp` follows the recommended guidelines for ROS Core packages in the [ROS 2 Developer Guide](https://docs.ros.org/en/rolling/Contributing/Developer-Guide.html#change-control-process).
 
 ### Change Requests [2.i]
 
-All changes will occur through a pull request, check [ROS 2 Developer Guide](https://index.ros.org/doc/ros2/Contributing/Developer-Guide/#change-control-process) for additional information.
+All changes will occur through a pull request, check [ROS 2 Developer Guide](https://docs.ros.org/en/rolling/Contributing/Developer-Guide.html#change-control-process) for additional information.
 
 ### Contributor Origin [2.ii]
 
@@ -51,7 +51,7 @@ This package uses DCO as its confirmation of contributor origin policy. More inf
 
 ### Peer Review Policy [2.iii]
 
-All pull requests will be peer-reviewed, check [ROS 2 Developer Guide](https://index.ros.org/doc/ros2/Contributing/Developer-Guide/#change-control-process) for additional information.
+All pull requests will be peer-reviewed, check [ROS 2 Developer Guide](https://docs.ros.org/en/rolling/Contributing/Developer-Guide.html#change-control-process) for additional information.
 
 ### Continuous Integration [2.iv]
 
@@ -82,13 +82,13 @@ The API is publicly available in its [ROS 2 API documentation](http://docs.ros2.
 
 The license for `rclcpp` is Apache 2.0, and a summary is in each source file, the type is declared in the [`package.xml`](./package.xml) manifest file, and a full copy of the license is in the [`LICENSE`](../LICENSE) file.
 
-There is an automated test which runs a linter that ensures each file has a license statement. [Here](http://build.ros2.org/view/Fpr/job/Fpr__rclcpp__ubuntu_focal_amd64/lastSuccessfulBuild/testReport/rclcpp/) can be found a list with the latest results of the various linters being run on the package.
+There is an automated test which runs a linter that ensures each file has a license statement. [Here](http://build.ros2.org/view/Rpr/job/Rpr__rclcpp__ubuntu_focal_amd64/lastCompletedBuild/testReport/rclcpp/) can be found a list with the latest results of the various linters being run on the package.
 
 ### Copyright Statements [3.iv]
 
 The copyright holders each provide a statement of copyright in each source code file in `rclcpp`.
 
-There is an automated test which runs a linter that ensures each file has at least one copyright statement. Latest linter result report can be seen [here](http://build.ros2.org/view/Fpr/job/Fpr__rclcpp__ubuntu_focal_amd64/lastSuccessfulBuild/testReport/rclcpp/copyright/).
+There is an automated test which runs a linter that ensures each file has at least one copyright statement. Latest linter result report can be seen [here](http://build.ros2.org/view/Rpr/job/Rpr__rclcpp__ubuntu_focal_amd64/lastCompletedBuild/testReport/rclcpp/copyright/).
 
 ## Testing [4]
 
@@ -111,7 +111,7 @@ The tests aim to cover both typical usage and corner cases, but are quantified b
 
 ### Coverage [4.iii]
 
-`rclcpp` follows the recommendations for ROS Core packages in the [ROS 2 Developer Guide](https://index.ros.org/doc/ros2/Contributing/Developer-Guide/#code-coverage), and opts to use line coverage instead of branch coverage.
+`rclcpp` follows the recommendations for ROS Core packages in the [ROS 2 Developer Guide](https://docs.ros.org/en/rolling/Contributing/Developer-Guide.html#code-coverage), and opts to use line coverage instead of branch coverage.
 
 This includes:
 
@@ -121,17 +121,25 @@ This includes:
 
 Changes are required to make a best effort to keep or increase coverage before being accepted, but decreases are allowed if properly justified and accepted by reviewers.
 
-Current coverage statistics can be viewed [here](https://ci.ros2.org/job/nightly_linux_coverage/lastSuccessfulBuild/cobertura/src_ros2_rclcpp_rclcpp_src_rclcpp/). A description of how coverage statistics are calculated is summarized in this page ["ROS 2 Onboarding Guide"](https://index.ros.org/doc/ros2/Contributing/ROS-2-On-boarding-Guide/#note-on-coverage-runs).
+Current coverage statistics can be viewed [here](https://ci.ros2.org/job/nightly_linux_coverage/lastCompletedBuild/cobertura/src_ros2_rclcpp_rclcpp_src_rclcpp/). A description of how coverage statistics are calculated is summarized in this page ["ROS 2 Onboarding Guide"](https://docs.ros.org/en/rolling/Contributing/Developer-Guide.html#note-on-coverage-runs).
 
 `rclcpp` has a line coverage `>= 95%`, which is calculated over all directories within `rclcpp` with the exception of the `experimental` directory.
 
 ### Performance [4.iv]
 
-It is not yet defined if this package requires performance testing and how addresses this topic.
+`rclcpp` follows the recommendations for performance testing of C/C++ code in the [ROS 2 Developer Guide](https://docs.ros.org/en/rolling/Contributing/Developer-Guide.html#performance), and opts to do performance analysis on each release rather than each change.
+
+The performance tests of `rclcpp` are located in the [test/benchmark directory](https://github.com/ros2/rclcpp/tree/master/rclcpp/test/benchmark).
+
+System level performance benchmarks that cover features of `rclcpp` can be found at:
+* [Benchmarks](http://build.ros2.org/view/Rci/job/Rci__benchmark_ubuntu_focal_amd64/BenchmarkTable/)
+* [Performance](http://build.ros2.org/view/Rci/job/Rci__nightly-performance_ubuntu_focal_amd64/lastCompletedBuild/)
+
+Changes that introduce regressions in performance must be adequately justified in order to be accepted and merged.
 
 ### Linters and Static Analysis [4.v]
 
-`rclcpp` uses and passes all the ROS2 standard linters and static analysis tools for a C++ package as described in the [ROS 2 Developer Guide](https://index.ros.org/doc/ros2/Contributing/Developer-Guide/#linters-and-static-analysis). Passing implies there are no linter/static errors when testing against CI of supported platforms.
+`rclcpp` uses and passes all the ROS2 standard linters and static analysis tools for a C++ package as described in the [ROS 2 Developer Guide](https://docs.ros.org/en/rolling/Contributing/Developer-Guide.html#linters-and-static-analysis). Passing implies there are no linter/static errors when testing against CI of supported platforms.
 
 Currently nightly test results can be seen here:
 * [linux-aarch64_release](https://ci.ros2.org/view/nightly/job/nightly_linux-aarch64_release/lastBuild/testReport/rclcpp/)
@@ -155,49 +163,49 @@ It also has several test dependencies, which do not affect the resulting quality
 
 The `libstatistics_collector` package provides lightweight aggregation utilities to collect statistics and measure message metrics.
 
-It is **Quality Level 3**, see its [Quality Declaration document](https://github.com/ros-tooling/libstatistics_collector/tree/master/QUALITY_DECLARATION.md).
+It is **Quality Level 1**, see its [Quality Declaration document](https://github.com/ros-tooling/libstatistics_collector/tree/master/QUALITY_DECLARATION.md).
 
 #### `rcl`
 
 `rcl` a library to support implementation of language specific ROS 2 Client Libraries.
 
-It is **Quality Level 3**, see its [Quality Declaration document](https://github.com/ros2/rcl/blob/master/rcl/QUALITY_DECLARATION.md).
+It is **Quality Level 1**, see its [Quality Declaration document](https://github.com/ros2/rcl/blob/master/rcl/QUALITY_DECLARATION.md).
 
 #### `rcl_yaml_param_parser`
 
 The `rcl_yaml_param_parser` package provides an API that is used to parse YAML configuration files which may be used to configure ROS and specific nodes.
 
-It is **Quality Level 3**, see its [Quality Declaration document](https://github.com/ros2/rcl/tree/master/rcl_yaml_param_parser/QUALITY_DECLARATION.md).
+It is **Quality Level 1**, see its [Quality Declaration document](https://github.com/ros2/rcl/tree/master/rcl_yaml_param_parser/QUALITY_DECLARATION.md).
 
 #### `rcpputils`
 
 The `rcpputils` package provides an API which contains common utilities and data structures useful when programming in C++.
 
-It is **Quality Level 2**, see its [Quality Declaration document](https://github.com/ros2/rcpputils/blob/master/QUALITY_DECLARATION.md).
+It is **Quality Level 1**, see its [Quality Declaration document](https://github.com/ros2/rcpputils/blob/master/QUALITY_DECLARATION.md).
 
 #### `rcutils`
 
 The `rcutils` package provides an API which contains common utilities and data structures useful when programming in C.
 
-It is **Quality Level 2**, see its [Quality Declaration document](https://github.com/ros2/rcutils/blob/master/QUALITY_DECLARATION.md).
+It is **Quality Level 1**, see its [Quality Declaration document](https://github.com/ros2/rcutils/blob/master/QUALITY_DECLARATION.md).
 
 #### `rmw`
 
 `rmw` is the ROS 2 middleware library.
 
-It is **Quality Level 2**, see its [Quality Declaration document](https://github.com/ros2/rmw/blob/master/rmw/QUALITY_DECLARATION.md).
+It is **Quality Level 1**, see its [Quality Declaration document](https://github.com/ros2/rmw/blob/master/rmw/QUALITY_DECLARATION.md).
 
 #### `statistics_msgs`
 
 The `statistics_msgs` package contains ROS 2 message definitions for reporting statistics for topics and system resources.
 
-It is **Quality Level 3**, see its [Quality Declaration document](https://github.com/ros2/rcl_interfaces/blob/master/statistics_msgs/QUALITY_DECLARATION.md).
+It is **Quality Level 1**, see its [Quality Declaration document](https://github.com/ros2/rcl_interfaces/blob/master/statistics_msgs/QUALITY_DECLARATION.md).
 
 #### `tracetools`
 
 The `tracetools` package provides utilities for instrumenting the code in `rclcpp` so that it may be traced for debugging and performance analysis.
 
-It is **Quality Level 2**, see its [Quality Declaration document](https://gitlab.com/micro-ROS/ros_tracing/ros2_tracing/-/blob/master/tracetools/QUALITY_DECLARATION.md).
+It is **Quality Level 1**, see its [Quality Declaration document](https://gitlab.com/ros-tracing/ros2_tracing/-/blob/master/tracetools/QUALITY_DECLARATION.md).
 
 ### Direct Runtime non-ROS Dependency [5.iii]
 

rclcpp/README.md

@@ -6,4 +6,4 @@ Visit the [rclcpp API documentation](http://docs.ros2.org/latest/api/rclcpp/) fo
 
 ## Quality Declaration
 
-This package claims to be in the **Quality Level 3** category, see the [Quality Declaration](QUALITY_DECLARATION.md) for more details.
+This package claims to be in the **Quality Level 1** category, see the [Quality Declaration](QUALITY_DECLARATION.md) for more details.

rclcpp/doc/notes_on_statically_typed_parameters.md

@@ -0,0 +1,141 @@
+# Notes on statically typed parameters
+
+## Introduction
+
+Until ROS 2 Foxy, all parameters could change type anytime, except if the user installed a parameter callback to reject a change.
+This could generate confusing errors, for example:
+
+```
+$ ros2 run demo_nodes_py listener &
+$ ros2 param set /listener use_sim_time not_a_boolean
+[ERROR] [1614712713.233733147] [listener]: use_sim_time parameter set to something besides a bool
+Set parameter successful
+$ ros2 param get /listener use_sim_time
+String value is: not_a_boolean
+```
+
+For most use cases, having static parameter types is enough.
+This article documents some of the decisions that were made when implementing static parameter types enforcement in:
+
+* https://github.com/ros2/rclcpp/pull/1522
+* https://github.com/ros2/rclpy/pull/683
+
+## Allowing dynamically typed parameters
+
+There might be some scenarios where dynamic typing is desired, so a `dynamic_typing` field was added to the [parameter descriptor](https://github.com/ros2/rcl_interfaces/blob/09b5ed93a733adb9deddc47f9a4a8c6e9f584667/rcl_interfaces/msg/ParameterDescriptor.msg#L25).
+It defaults to `false`.
+
+For example:
+
+```cpp
+rcl_interfaces::msg::ParameterDescriptor descriptor;
+descriptor.dynamic_typing = true;
+
+node->declare_parameter("dynamically_typed_parameter", rclcpp::ParameterValue{}, descriptor);
+```
+
+```py
+rcl_interfaces.msg.ParameterDescriptor descriptor;
+descriptor.dynamic_typing = True;
+
+node.declare_parameter("dynamically_typed_parameter", None, descriptor);
+```
+
+## How is the parameter type specified?
+
+The parameter type will be inferred from the default value provided when declaring it.
+
+## Statically typed parameters when allowing undeclared parameters
+
+When undeclared parameters are allowed and a parameter is set without a previous declaration, the parameter will be dynamically typed.
+This is consistent with other allowed behaviors when undeclared parameters are allowed, e.g. trying to get an undeclared parameter returns "NOT_SET".
+Parameter declarations will remain special and dynamic or static typing will be used based on the parameter descriptor (default to static).
+
+## Declaring a parameter without a default value
+
+There might be cases were a default value does not make sense and the user must always provide an override.
+In those cases, the parameter type can be specified explicitly:
+
+```cpp
+// method signature
+template<typename T>
+Node::declare_parameter<T>(std::string name, rcl_interfaces::msg::ParameterDescriptor = rcl_interfaces::msg::ParameterDescriptor{});
+// or alternatively
+Node::declare_parameter(std::string name, rclcpp::ParameterType type, rcl_interfaces::msg::ParameterDescriptor = rcl_interfaces::msg::ParameterDescriptor{});
+
+// examples
+node->declare_parameter<int64_t>("my_integer_parameter");  // declare an integer parameter
+node->declare_parameter("another_integer_parameter", rclcpp::ParameterType::PARAMETER_INTEGER);  // another way to do the same
+```
+
+```py
+# method signature
+Node.declare_parameter(name: str, param_type: rclpy.Parameter.Type, descriptor: rcl_interfaces.msg.ParameterDescriptor = rcl_interfaces.msg.ParameterDescriptor())
+
+# example
+node.declare_parameter('my_integer_parameter', rclpy.Parameter.Type.INTEGER);  # declare an integer parameter
+```
+
+If the parameter may be unused, but when used requires a parameter override, then you could conditionally declare it:
+
+```cpp
+auto mode = node->declare_parameter("mode", "modeA");  // "mode" parameter is an string
+if (mode == "modeB") {
+    node->declare_parameter<int64_t>("param_needed_when_mode_b");  // when "modeB", the user must provide "param_needed_when_mode_b"
+}
+```
+
+## Other migration notes
+
+Declaring a parameter with only a name is deprecated:
+
+```cpp
+node->declare_parameter("my_param");  // this generates a build warning
+```
+
+```py
+node.declare_parameter("my_param");  # this generates a python user warning
+```
+
+Before, you could initialize a parameter with the "NOT SET" value (in cpp `rclcpp::ParameterValue{}`, in python `None`).
+Now this will throw an exception in both cases:
+
+```cpp
+node->declare_parameter("my_param", rclcpp::ParameterValue{});  // not valid, will throw exception
+```
+
+```py
+node.declare_parameter("my_param", None);  # not valid, will raise error
+```
+
+## Possible improvements
+
+### Easier way to declare dynamically typed parameters
+
+Declaring a dynamically typed parameter in `rclcpp` could be considered to be a bit verbose:
+
+```cpp
+rcl_interfaces::msg::ParameterDescriptor descriptor;
+descriptor.dynamic_typing = true;
+
+node->declare_parameter(name, rclcpp::ParameterValue{}, descriptor);
+```
+
+the following ways could be supported to make it simpler:
+
+```cpp
+node->declare_parameter(name, rclcpp::PARAMETER_DYNAMIC);
+node->declare_parameter(name, default_value, rclcpp::PARAMETER_DYNAMIC);
+```
+
+or alternatively:
+
+```cpp
+node->declare_parameter(name, default_value, rclcpp::ParameterDescriptor{}.dynamic_typing());
+```
+
+For `rclpy`, there's already a short way to do it:
+
+```py
+node.declare_parameter(name, default_value, rclpy.ParameterDescriptor(dynamic_typing=true));
+```

rclcpp/include/rclcpp/allocator/allocator_common.hpp

@@ -29,71 +29,23 @@ namespace allocator
 template<typename T, typename Alloc>
 using AllocRebind = typename std::allocator_traits<Alloc>::template rebind_traits<T>;
 
-template<typename Alloc>
-void * retyped_allocate(size_t size, void * untyped_allocator)
+/// Return the equivalent rcl_allocator_t for the C++ standard allocator.
+/**
+ * This assumes that the user intent behind both allocators is the
+ * same: Using system malloc for allocation.
+ *
+ * If you're using a custom allocator in ROS, you'll need to provide
+ * your own overload for this function.
+ */
+template<typename T>
+rcl_allocator_t get_rcl_allocator(std::allocator<T> allocator)
 {
-  auto typed_allocator = static_cast<Alloc *>(untyped_allocator);
-  if (!typed_allocator) {
-    throw std::runtime_error("Received incorrect allocator type");
-  }
-  return std::allocator_traits<Alloc>::allocate(*typed_allocator, size);
-}
-
-template<typename T, typename Alloc>
-void retyped_deallocate(void * untyped_pointer, void * untyped_allocator)
-{
-  auto typed_allocator = static_cast<Alloc *>(untyped_allocator);
-  if (!typed_allocator) {
-    throw std::runtime_error("Received incorrect allocator type");
-  }
-  auto typed_ptr = static_cast<T *>(untyped_pointer);
-  std::allocator_traits<Alloc>::deallocate(*typed_allocator, typed_ptr, 1);
-}
-
-template<typename T, typename Alloc>
-void * retyped_reallocate(void * untyped_pointer, size_t size, void * untyped_allocator)
-{
-  auto typed_allocator = static_cast<Alloc *>(untyped_allocator);
-  if (!typed_allocator) {
-    throw std::runtime_error("Received incorrect allocator type");
-  }
-  auto typed_ptr = static_cast<T *>(untyped_pointer);
-  std::allocator_traits<Alloc>::deallocate(*typed_allocator, typed_ptr, 1);
-  return std::allocator_traits<Alloc>::allocate(*typed_allocator, size);
-}
-
-
-// Convert a std::allocator_traits-formatted Allocator into an rcl allocator
-template<
-  typename T,
-  typename Alloc,
-  typename std::enable_if<!std::is_same<Alloc, std::allocator<void>>::value>::type * = nullptr>
-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.deallocate = &retyped_deallocate<T, Alloc>;
-  rcl_allocator.reallocate = &retyped_reallocate<T, Alloc>;
-  rcl_allocator.state = &allocator;
-#else
   (void)allocator;  // Remove warning
-#endif
-  return rcl_allocator;
-}
-
-// TODO(jacquelinekay) Workaround for an incomplete implementation of std::allocator<void>
-template<
-  typename T,
-  typename Alloc,
-  typename std::enable_if<std::is_same<Alloc, std::allocator<void>>::value>::type * = nullptr>
-rcl_allocator_t get_rcl_allocator(Alloc & allocator)
-{
-  (void)allocator;
   return rcl_get_default_allocator();
 }
 
 }  // namespace allocator
+
 }  // namespace rclcpp
 
 #endif  // RCLCPP__ALLOCATOR__ALLOCATOR_COMMON_HPP_

rclcpp/include/rclcpp/any_executable.hpp

@@ -47,14 +47,9 @@ struct AnyExecutable
   // These are used to keep the scope on the containing items
   rclcpp::CallbackGroup::SharedPtr callback_group;
   rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_base;
+  std::shared_ptr<void> data;
 };
 
-namespace executor
-{
-
-using AnyExecutable [[deprecated("use rclcpp::AnyExecutable instead")]] = AnyExecutable;
-
-}  // namespace executor
 }  // namespace rclcpp
 
 #endif  // RCLCPP__ANY_EXECUTABLE_HPP_

rclcpp/include/rclcpp/any_service_callback.hpp

@@ -107,12 +107,12 @@ public:
       TRACEPOINT(
         rclcpp_callback_register,
         static_cast<const void *>(this),
-        get_symbol(shared_ptr_callback_));
+        tracetools::get_symbol(shared_ptr_callback_));
     } else if (shared_ptr_with_request_header_callback_) {
       TRACEPOINT(
         rclcpp_callback_register,
         static_cast<const void *>(this),
-        get_symbol(shared_ptr_with_request_header_callback_));
+        tracetools::get_symbol(shared_ptr_with_request_header_callback_));
     }
 #endif  // TRACETOOLS_DISABLED
   }

rclcpp/include/rclcpp/any_subscription_callback.hpp

@@ -15,253 +15,394 @@
 #ifndef RCLCPP__ANY_SUBSCRIPTION_CALLBACK_HPP_
 #define RCLCPP__ANY_SUBSCRIPTION_CALLBACK_HPP_
 
-#include <rmw/types.h>
-
 #include <functional>
 #include <memory>
 #include <stdexcept>
 #include <type_traits>
 #include <utility>
+#include <variant>  // NOLINT[build/include_order]
 
-#include "rclcpp/allocator/allocator_common.hpp"
-#include "rclcpp/function_traits.hpp"
-#include "rclcpp/message_info.hpp"
-#include "rclcpp/visibility_control.hpp"
 #include "tracetools/tracetools.h"
 #include "tracetools/utils.hpp"
 
+#include "rclcpp/allocator/allocator_common.hpp"
+#include "rclcpp/detail/subscription_callback_type_helper.hpp"
+#include "rclcpp/function_traits.hpp"
+#include "rclcpp/message_info.hpp"
+
+template<class>
+inline constexpr bool always_false_v = false;
+
 namespace rclcpp
 {
 
-template<typename MessageT, typename Alloc>
-class AnySubscriptionCallback
+namespace detail
 {
-  using MessageAllocTraits = allocator::AllocRebind<MessageT, Alloc>;
+
+template<typename MessageT, typename AllocatorT>
+struct MessageDeleterHelper
+{
+  using MessageAllocTraits = allocator::AllocRebind<MessageT, AllocatorT>;
   using MessageAlloc = typename MessageAllocTraits::allocator_type;
   using MessageDeleter = allocator::Deleter<MessageAlloc, MessageT>;
-  using ConstMessageSharedPtr = std::shared_ptr<const MessageT>;
-  using MessageUniquePtr = std::unique_ptr<MessageT, MessageDeleter>;
+};
 
-  using SharedPtrCallback = std::function<void (const std::shared_ptr<MessageT>)>;
-  using SharedPtrWithInfoCallback =
-    std::function<void (const std::shared_ptr<MessageT>, const rclcpp::MessageInfo &)>;
-  using ConstSharedPtrCallback = std::function<void (const std::shared_ptr<const MessageT>)>;
-  using ConstSharedPtrWithInfoCallback =
-    std::function<void (const std::shared_ptr<const MessageT>, const rclcpp::MessageInfo &)>;
-  using UniquePtrCallback = std::function<void (MessageUniquePtr)>;
+template<typename MessageT, typename AllocatorT>
+struct AnySubscriptionCallbackHelper
+{
+  using MessageDeleter = typename MessageDeleterHelper<MessageT, AllocatorT>::MessageDeleter;
+
+  using ConstRefCallback =
+    std::function<void (const MessageT &)>;
+  using ConstRefWithInfoCallback =
+    std::function<void (const MessageT &, const rclcpp::MessageInfo &)>;
+
+  using UniquePtrCallback =
+    std::function<void (std::unique_ptr<MessageT, MessageDeleter>)>;
   using UniquePtrWithInfoCallback =
-    std::function<void (MessageUniquePtr, const rclcpp::MessageInfo &)>;
+    std::function<void (std::unique_ptr<MessageT, MessageDeleter>, const rclcpp::MessageInfo &)>;
 
-  SharedPtrCallback shared_ptr_callback_;
-  SharedPtrWithInfoCallback shared_ptr_with_info_callback_;
-  ConstSharedPtrCallback const_shared_ptr_callback_;
-  ConstSharedPtrWithInfoCallback const_shared_ptr_with_info_callback_;
-  UniquePtrCallback unique_ptr_callback_;
-  UniquePtrWithInfoCallback unique_ptr_with_info_callback_;
+  using SharedConstPtrCallback =
+    std::function<void (std::shared_ptr<const MessageT>)>;
+  using SharedConstPtrWithInfoCallback =
+    std::function<void (std::shared_ptr<const MessageT>, const rclcpp::MessageInfo &)>;
+
+  using ConstRefSharedConstPtrCallback =
+    std::function<void (const std::shared_ptr<const MessageT> &)>;
+  using ConstRefSharedConstPtrWithInfoCallback =
+    std::function<void (const std::shared_ptr<const MessageT> &, const rclcpp::MessageInfo &)>;
+
+  // Deprecated signatures:
+  using SharedPtrCallback =
+    std::function<void (std::shared_ptr<MessageT>)>;
+  using SharedPtrWithInfoCallback =
+    std::function<void (std::shared_ptr<MessageT>, const rclcpp::MessageInfo &)>;
+
+  using variant_type = std::variant<
+    ConstRefCallback,
+    ConstRefWithInfoCallback,
+    UniquePtrCallback,
+    UniquePtrWithInfoCallback,
+    SharedConstPtrCallback,
+    SharedConstPtrWithInfoCallback,
+    ConstRefSharedConstPtrCallback,
+    ConstRefSharedConstPtrWithInfoCallback,
+    SharedPtrCallback,
+    SharedPtrWithInfoCallback
+  >;
+};
+
+}  // namespace detail
+
+template<
+  typename MessageT,
+  typename AllocatorT = std::allocator<void>
+>
+class AnySubscriptionCallback
+{
+private:
+  using HelperT = typename rclcpp::detail::AnySubscriptionCallbackHelper<MessageT, AllocatorT>;
+  using MessageDeleterHelper = rclcpp::detail::MessageDeleterHelper<MessageT, AllocatorT>;
+
+  using MessageAllocTraits = typename MessageDeleterHelper::MessageAllocTraits;
+  using MessageAlloc = typename MessageDeleterHelper::MessageAlloc;
+  using MessageDeleter = typename MessageDeleterHelper::MessageDeleter;
+
+  // See AnySubscriptionCallbackHelper for the types of these.
+  using ConstRefCallback = typename HelperT::ConstRefCallback;
+  using ConstRefWithInfoCallback = typename HelperT::ConstRefWithInfoCallback;
+
+  using UniquePtrCallback = typename HelperT::UniquePtrCallback;
+  using UniquePtrWithInfoCallback = typename HelperT::UniquePtrWithInfoCallback;
+
+  using SharedConstPtrCallback = typename HelperT::SharedConstPtrCallback;
+  using SharedConstPtrWithInfoCallback = typename HelperT::SharedConstPtrWithInfoCallback;
+
+  using ConstRefSharedConstPtrCallback =
+    typename HelperT::ConstRefSharedConstPtrCallback;
+  using ConstRefSharedConstPtrWithInfoCallback =
+    typename HelperT::ConstRefSharedConstPtrWithInfoCallback;
+
+  using SharedPtrCallback = typename HelperT::SharedPtrCallback;
+  using SharedPtrWithInfoCallback = typename HelperT::SharedPtrWithInfoCallback;
 
 public:
-  explicit AnySubscriptionCallback(std::shared_ptr<Alloc> allocator)
-  : shared_ptr_callback_(nullptr), shared_ptr_with_info_callback_(nullptr),
-    const_shared_ptr_callback_(nullptr), const_shared_ptr_with_info_callback_(nullptr),
-    unique_ptr_callback_(nullptr), unique_ptr_with_info_callback_(nullptr)
+  explicit
+  AnySubscriptionCallback(const AllocatorT & allocator = AllocatorT())  // NOLINT[runtime/explicit]
   {
-    message_allocator_ = std::make_shared<MessageAlloc>(*allocator.get());
-    allocator::set_allocator_for_deleter(&message_deleter_, message_allocator_.get());
+    message_allocator_ = allocator;
+    allocator::set_allocator_for_deleter(&message_deleter_, &message_allocator_);
+  }
+
+  [[deprecated("use AnySubscriptionCallback(const AllocatorT & allocator) instead")]]
+  explicit
+  AnySubscriptionCallback(std::shared_ptr<AllocatorT> allocator)  // NOLINT[runtime/explicit]
+  {
+    if (allocator == nullptr) {
+      throw std::runtime_error("invalid allocator");
+    }
+    message_allocator_ = *allocator;
+    allocator::set_allocator_for_deleter(&message_deleter_, &message_allocator_);
   }
 
   AnySubscriptionCallback(const AnySubscriptionCallback &) = default;
 
-  template<
-    typename CallbackT,
-    typename std::enable_if<
-      rclcpp::function_traits::same_arguments<
-        CallbackT,
-        SharedPtrCallback
-      >::value
-    >::type * = nullptr
-  >
-  void set(CallbackT callback)
+  /// Generic function for setting the callback.
+  /**
+   * There are specializations that overload this in order to deprecate some
+   * callback signatures, and also to fix ambiguity between shared_ptr and
+   * unique_ptr callback signatures when using them with lambda functions.
+   */
+  template<typename CallbackT>
+  AnySubscriptionCallback<MessageT, AllocatorT>
+  set(CallbackT callback)
   {
-    shared_ptr_callback_ = callback;
+    // Use the SubscriptionCallbackTypeHelper to determine the actual type of
+    // the CallbackT, in terms of std::function<...>, which does not happen
+    // automatically with lambda functions in cases where the arguments can be
+    // converted to one another, e.g. shared_ptr and unique_ptr.
+    using scbth = detail::SubscriptionCallbackTypeHelper<MessageT, CallbackT>;
+
+    // Determine if the given CallbackT is a deprecated signature or not.
+    constexpr auto is_deprecated =
+      rclcpp::function_traits::same_arguments<
+      typename scbth::callback_type,
+      std::function<void(std::shared_ptr<MessageT>)>
+      >::value
+      ||
+      rclcpp::function_traits::same_arguments<
+      typename scbth::callback_type,
+      std::function<void(std::shared_ptr<MessageT>, const rclcpp::MessageInfo &)>
+      >::value;
+
+    // Use the discovered type to force the type of callback when assigning
+    // into the variant.
+    if constexpr (is_deprecated) {
+      // If deprecated, call sub-routine that is deprecated.
+      set_deprecated(static_cast<typename scbth::callback_type>(callback));
+    } else {
+      // Otherwise just assign it.
+      callback_variant_ = static_cast<typename scbth::callback_type>(callback);
+    }
+
+    // Return copy of self for easier testing, normally will be compiled out.
+    return *this;
   }
 
-  template<
-    typename CallbackT,
-    typename std::enable_if<
-      rclcpp::function_traits::same_arguments<
-        CallbackT,
-        SharedPtrWithInfoCallback
-      >::value
-    >::type * = nullptr
-  >
-  void set(CallbackT callback)
+  /// Function for shared_ptr to non-const MessageT, which is deprecated.
+  // TODO(wjwwood): enable this deprecation after Galactic
+  // [[deprecated(
+  //   "use 'void (std::shared_ptr<const MessageT>)' instead"
+  // )]]
+  void
+  set_deprecated(std::function<void(std::shared_ptr<MessageT>)> callback)
+  // set(CallbackT callback)
   {
-    shared_ptr_with_info_callback_ = callback;
+    callback_variant_ = callback;
   }
 
-  template<
-    typename CallbackT,
-    typename std::enable_if<
-      rclcpp::function_traits::same_arguments<
-        CallbackT,
-        ConstSharedPtrCallback
-      >::value
-    >::type * = nullptr
-  >
-  void set(CallbackT callback)
+  /// Function for shared_ptr to non-const MessageT with MessageInfo, which is deprecated.
+  // TODO(wjwwood): enable this deprecation after Galactic
+  // [[deprecated(
+  //   "use 'void (std::shared_ptr<const MessageT>, const rclcpp::MessageInfo &)' instead"
+  // )]]
+  void
+  set_deprecated(
+    std::function<void(std::shared_ptr<MessageT>, const rclcpp::MessageInfo &)> callback)
   {
-    const_shared_ptr_callback_ = callback;
+    callback_variant_ = callback;
   }
 
-  template<
-    typename CallbackT,
-    typename std::enable_if<
-      rclcpp::function_traits::same_arguments<
-        CallbackT,
-        ConstSharedPtrWithInfoCallback
-      >::value
-    >::type * = nullptr
-  >
-  void set(CallbackT callback)
+  std::unique_ptr<MessageT, MessageDeleter>
+  create_unique_ptr_from_shared_ptr_message(const std::shared_ptr<const MessageT> & message)
   {
-    const_shared_ptr_with_info_callback_ = callback;
+    auto ptr = MessageAllocTraits::allocate(message_allocator_, 1);
+    MessageAllocTraits::construct(message_allocator_, ptr, *message);
+    return std::unique_ptr<MessageT, MessageDeleter>(ptr, message_deleter_);
   }
 
-  template<
-    typename CallbackT,
-    typename std::enable_if<
-      rclcpp::function_traits::same_arguments<
-        CallbackT,
-        UniquePtrCallback
-      >::value
-    >::type * = nullptr
-  >
-  void set(CallbackT callback)
-  {
-    unique_ptr_callback_ = callback;
-  }
-
-  template<
-    typename CallbackT,
-    typename std::enable_if<
-      rclcpp::function_traits::same_arguments<
-        CallbackT,
-        UniquePtrWithInfoCallback
-      >::value
-    >::type * = nullptr
-  >
-  void set(CallbackT callback)
-  {
-    unique_ptr_with_info_callback_ = callback;
-  }
-
-  void dispatch(
-    std::shared_ptr<MessageT> message, const rclcpp::MessageInfo & message_info)
+  void
+  dispatch(
+    std::shared_ptr<MessageT> message,
+    const rclcpp::MessageInfo & message_info)
   {
     TRACEPOINT(callback_start, static_cast<const void *>(this), false);
-    if (shared_ptr_callback_) {
-      shared_ptr_callback_(message);
-    } else if (shared_ptr_with_info_callback_) {
-      shared_ptr_with_info_callback_(message, message_info);
-    } else if (const_shared_ptr_callback_) {
-      const_shared_ptr_callback_(message);
-    } else if (const_shared_ptr_with_info_callback_) {
-      const_shared_ptr_with_info_callback_(message, message_info);
-    } else if (unique_ptr_callback_) {
-      auto ptr = MessageAllocTraits::allocate(*message_allocator_.get(), 1);
-      MessageAllocTraits::construct(*message_allocator_.get(), ptr, *message);
-      unique_ptr_callback_(MessageUniquePtr(ptr, message_deleter_));
-    } else if (unique_ptr_with_info_callback_) {
-      auto ptr = MessageAllocTraits::allocate(*message_allocator_.get(), 1);
-      MessageAllocTraits::construct(*message_allocator_.get(), ptr, *message);
-      unique_ptr_with_info_callback_(MessageUniquePtr(ptr, message_deleter_), message_info);
-    } else {
-      throw std::runtime_error("unexpected message without any callback set");
-    }
-    TRACEPOINT(callback_end, static_cast<const void *>(this));
-  }
-
-  void dispatch_intra_process(
-    ConstMessageSharedPtr message, const rclcpp::MessageInfo & message_info)
-  {
-    TRACEPOINT(callback_start, static_cast<const void *>(this), true);
-    if (const_shared_ptr_callback_) {
-      const_shared_ptr_callback_(message);
-    } else if (const_shared_ptr_with_info_callback_) {
-      const_shared_ptr_with_info_callback_(message, message_info);
-    } else {
-      if (
-        unique_ptr_callback_ || unique_ptr_with_info_callback_ ||
-        shared_ptr_callback_ || shared_ptr_with_info_callback_)
-      {
-        throw std::runtime_error(
-                "unexpected dispatch_intra_process const shared "
-                "message call with no const shared_ptr callback");
-      } else {
-        throw std::runtime_error("unexpected message without any callback set");
+    // Check if the variant is "unset", throw if it is.
+    if (callback_variant_.index() == 0) {
+      if (std::get<0>(callback_variant_) == nullptr) {
+        // This can happen if it is default initialized, or if it is assigned nullptr.
+        throw std::runtime_error("dispatch called on an unset AnySubscriptionCallback");
       }
     }
+    // Dispatch.
+    std::visit(
+      [&message, &message_info, this](auto && callback) {
+        using T = std::decay_t<decltype(callback)>;
+
+        if constexpr (std::is_same_v<T, ConstRefCallback>) {
+          callback(*message);
+        } else if constexpr (std::is_same_v<T, ConstRefWithInfoCallback>) {
+          callback(*message, message_info);
+        } else if constexpr (std::is_same_v<T, UniquePtrCallback>) {
+          callback(create_unique_ptr_from_shared_ptr_message(message));
+        } else if constexpr (std::is_same_v<T, UniquePtrWithInfoCallback>) {
+          callback(create_unique_ptr_from_shared_ptr_message(message), message_info);
+        } else if constexpr (  // NOLINT[readability/braces]
+          std::is_same_v<T, SharedConstPtrCallback>||
+          std::is_same_v<T, ConstRefSharedConstPtrCallback>||
+          std::is_same_v<T, SharedPtrCallback>)
+        {
+          callback(message);
+        } else if constexpr (  // NOLINT[readability/braces]
+          std::is_same_v<T, SharedConstPtrWithInfoCallback>||
+          std::is_same_v<T, ConstRefSharedConstPtrWithInfoCallback>||
+          std::is_same_v<T, SharedPtrWithInfoCallback>)
+        {
+          callback(message, message_info);
+        } else {
+          static_assert(always_false_v<T>, "unhandled callback type");
+        }
+      }, callback_variant_);
     TRACEPOINT(callback_end, static_cast<const void *>(this));
   }
 
-  void dispatch_intra_process(
-    MessageUniquePtr message, const rclcpp::MessageInfo & message_info)
+  void
+  dispatch_intra_process(
+    std::shared_ptr<const MessageT> message,
+    const rclcpp::MessageInfo & message_info)
   {
     TRACEPOINT(callback_start, static_cast<const void *>(this), true);
-    if (shared_ptr_callback_) {
-      typename std::shared_ptr<MessageT> shared_message = std::move(message);
-      shared_ptr_callback_(shared_message);
-    } else if (shared_ptr_with_info_callback_) {
-      typename std::shared_ptr<MessageT> shared_message = std::move(message);
-      shared_ptr_with_info_callback_(shared_message, message_info);
-    } else if (unique_ptr_callback_) {
-      unique_ptr_callback_(std::move(message));
-    } else if (unique_ptr_with_info_callback_) {
-      unique_ptr_with_info_callback_(std::move(message), message_info);
-    } else if (const_shared_ptr_callback_ || const_shared_ptr_with_info_callback_) {
-      throw std::runtime_error(
-              "unexpected dispatch_intra_process unique message call"
-              " with const shared_ptr callback");
-    } else {
-      throw std::runtime_error("unexpected message without any callback set");
+    // Check if the variant is "unset", throw if it is.
+    if (callback_variant_.index() == 0) {
+      if (std::get<0>(callback_variant_) == nullptr) {
+        // This can happen if it is default initialized, or if it is assigned nullptr.
+        throw std::runtime_error("dispatch called on an unset AnySubscriptionCallback");
+      }
     }
+    // Dispatch.
+    std::visit(
+      [&message, &message_info, this](auto && callback) {
+        using T = std::decay_t<decltype(callback)>;
+
+        if constexpr (std::is_same_v<T, ConstRefCallback>) {
+          callback(*message);
+        } else if constexpr (std::is_same_v<T, ConstRefWithInfoCallback>) {
+          callback(*message, message_info);
+        } else if constexpr (  // NOLINT[readability/braces]
+          std::is_same_v<T, UniquePtrCallback>||
+          std::is_same_v<T, SharedPtrCallback>)
+        {
+          callback(create_unique_ptr_from_shared_ptr_message(message));
+        } else if constexpr (  // NOLINT[readability/braces]
+          std::is_same_v<T, UniquePtrWithInfoCallback>||
+          std::is_same_v<T, SharedPtrWithInfoCallback>)
+        {
+          callback(create_unique_ptr_from_shared_ptr_message(message), message_info);
+        } else if constexpr (  // NOLINT[readability/braces]
+          std::is_same_v<T, SharedConstPtrCallback>||
+          std::is_same_v<T, ConstRefSharedConstPtrCallback>)
+        {
+          callback(message);
+        } else if constexpr (  // NOLINT[readability/braces]
+          std::is_same_v<T, SharedConstPtrWithInfoCallback>||
+          std::is_same_v<T, ConstRefSharedConstPtrWithInfoCallback>)
+        {
+          callback(message, message_info);
+        } else {
+          static_assert(always_false_v<T>, "unhandled callback type");
+        }
+      }, callback_variant_);
     TRACEPOINT(callback_end, static_cast<const void *>(this));
   }
 
-  bool use_take_shared_method() const
+  void
+  dispatch_intra_process(
+    std::unique_ptr<MessageT, MessageDeleter> message,
+    const rclcpp::MessageInfo & message_info)
   {
-    return const_shared_ptr_callback_ || const_shared_ptr_with_info_callback_;
+    TRACEPOINT(callback_start, static_cast<const void *>(this), true);
+    // Check if the variant is "unset", throw if it is.
+    if (callback_variant_.index() == 0) {
+      if (std::get<0>(callback_variant_) == nullptr) {
+        // This can happen if it is default initialized, or if it is assigned nullptr.
+        throw std::runtime_error("dispatch called on an unset AnySubscriptionCallback");
+      }
+    }
+    // Dispatch.
+    std::visit(
+      [&message, &message_info](auto && callback) {
+        using T = std::decay_t<decltype(callback)>;
+
+        if constexpr (std::is_same_v<T, ConstRefCallback>) {
+          callback(*message);
+        } else if constexpr (std::is_same_v<T, ConstRefWithInfoCallback>) {
+          callback(*message, message_info);
+        } else if constexpr (  // NOLINT[readability/braces]
+          std::is_same_v<T, UniquePtrCallback>||
+          std::is_same_v<T, SharedConstPtrCallback>||
+          std::is_same_v<T, ConstRefSharedConstPtrCallback>||
+          std::is_same_v<T, SharedPtrCallback>)
+        {
+          callback(std::move(message));
+        } else if constexpr (  // NOLINT[readability/braces]
+          std::is_same_v<T, UniquePtrWithInfoCallback>||
+          std::is_same_v<T, SharedConstPtrWithInfoCallback>||
+          std::is_same_v<T, ConstRefSharedConstPtrWithInfoCallback>||
+          std::is_same_v<T, SharedPtrWithInfoCallback>)
+        {
+          callback(std::move(message), message_info);
+        } else {
+          static_assert(always_false_v<T>, "unhandled callback type");
+        }
+      }, callback_variant_);
+    TRACEPOINT(callback_end, static_cast<const void *>(this));
   }
 
-  void register_callback_for_tracing()
+  constexpr
+  bool
+  use_take_shared_method() const
+  {
+    return
+      std::holds_alternative<SharedConstPtrCallback>(callback_variant_) ||
+      std::holds_alternative<SharedConstPtrWithInfoCallback>(callback_variant_) ||
+      std::holds_alternative<ConstRefSharedConstPtrCallback>(callback_variant_) ||
+      std::holds_alternative<ConstRefSharedConstPtrWithInfoCallback>(callback_variant_);
+  }
+
+  void
+  register_callback_for_tracing()
   {
 #ifndef TRACETOOLS_DISABLED
-    if (shared_ptr_callback_) {
-      TRACEPOINT(
-        rclcpp_callback_register,
-        static_cast<const void *>(this),
-        get_symbol(shared_ptr_callback_));
-    } else if (shared_ptr_with_info_callback_) {
-      TRACEPOINT(
-        rclcpp_callback_register,
-        static_cast<const void *>(this),
-        get_symbol(shared_ptr_with_info_callback_));
-    } else if (unique_ptr_callback_) {
-      TRACEPOINT(
-        rclcpp_callback_register,
-        static_cast<const void *>(this),
-        get_symbol(unique_ptr_callback_));
-    } else if (unique_ptr_with_info_callback_) {
-      TRACEPOINT(
-        rclcpp_callback_register,
-        static_cast<const void *>(this),
-        get_symbol(unique_ptr_with_info_callback_));
-    }
+    std::visit(
+      [this](auto && callback) {
+        TRACEPOINT(
+          rclcpp_callback_register,
+          static_cast<const void *>(this),
+          tracetools::get_symbol(callback));
+      }, callback_variant_);
 #endif  // TRACETOOLS_DISABLED
   }
 
+  typename HelperT::variant_type &
+  get_variant()
+  {
+    return callback_variant_;
+  }
+
+  const typename HelperT::variant_type &
+  get_variant() const
+  {
+    return callback_variant_;
+  }
+
 private:
-  std::shared_ptr<MessageAlloc> message_allocator_;
+  // TODO(wjwwood): switch to inheriting from std::variant (i.e. HelperT::variant_type) once
+  // inheriting from std::variant is realistic (maybe C++23?), see:
+  //   http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2162r0.html
+  // For now, compose the variant into this class as a private attribute.
+  typename HelperT::variant_type callback_variant_;
+
+  MessageAlloc message_allocator_;
   MessageDeleter message_deleter_;
 };
 

rclcpp/include/rclcpp/callback_group.hpp

@@ -85,8 +85,8 @@ public:
    * group, or after, is irrelevant; the callback group will be automatically
    * added to the executor in either case.
    *
-   * \param[in] group_type They type of the callback group.
-   * \param[in] automatically_add_to_executor_with_node a boolean which
+   * \param[in] group_type The type of the callback group.
+   * \param[in] automatically_add_to_executor_with_node A boolean that
    *   determines whether a callback group is automatically added to an executor
    *   with the node with which it is associated.
    */
@@ -222,13 +222,6 @@ private:
   }
 };
 
-namespace callback_group
-{
-
-using CallbackGroupType [[deprecated("use rclcpp::CallbackGroupType instead")]] = CallbackGroupType;
-using CallbackGroup [[deprecated("use rclcpp::CallbackGroup instead")]] = CallbackGroup;
-
-}  // namespace callback_group
 }  // namespace rclcpp
 
 #endif  // RCLCPP__CALLBACK_GROUP_HPP_

rclcpp/include/rclcpp/clock.hpp

@@ -136,7 +136,7 @@ private:
   RCLCPP_PUBLIC
   static void
   on_time_jump(
-    const struct rcl_time_jump_t * time_jump,
+    const rcl_time_jump_t * time_jump,
     bool before_jump,
     void * user_data);
 

rclcpp/include/rclcpp/context.hpp

@@ -150,7 +150,7 @@ public:
    */
   RCLCPP_PUBLIC
   std::string
-  shutdown_reason();
+  shutdown_reason() const;
 
   /// Shutdown the context, making it uninitialized and therefore invalid for derived entities.
   /**
@@ -248,67 +248,6 @@ public:
   void
   interrupt_all_sleep_for();
 
-  /// Get a handle to the guard condition which is triggered when interrupted.
-  /**
-   * This guard condition is triggered any time interrupt_all_wait_sets() is
-   * called, which may be called by the user, or shutdown().
-   * And in turn, shutdown() may be called by the user, the destructor of this
-   * context, or the signal handler if installed and shutdown_on_sigint is true
-   * for this context.
-   *
-   * The first time that this function is called for a given wait set a new guard
-   * condition will be created and returned; thereafter the same guard condition
-   * will be returned for the same wait set.
-   * This mechanism is designed to ensure that the same guard condition is not
-   * reused across wait sets (e.g., when using multiple executors in the same
-   * process).
-   * This method will throw an exception if initialization of the guard
-   * condition fails.
-   *
-   * The returned guard condition needs to be released with the
-   * release_interrupt_guard_condition() method in order to reclaim resources.
-   *
-   * \param[in] wait_set Pointer to the rcl_wait_set_t that will be using the
-   *   resulting guard condition.
-   * \return Pointer to the guard condition.
-   * \throws anything rclcpp::exceptions::throw_from_rcl_error can throw.
-   */
-  RCLCPP_PUBLIC
-  rcl_guard_condition_t *
-  get_interrupt_guard_condition(rcl_wait_set_t * wait_set);
-
-  /// Release the previously allocated guard condition which is triggered when interrupted.
-  /**
-   * If you previously called get_interrupt_guard_condition() for a given wait
-   * set to get a interrupt guard condition, then you should call
-   * release_interrupt_guard_condition() when you're done, to free that
-   * condition.
-   * Will throw an exception if get_interrupt_guard_condition() wasn't
-   * previously called for the given wait set.
-   *
-   * After calling this, the pointer returned by get_interrupt_guard_condition()
-   * for the given wait_set is invalid.
-   *
-   * \param[in] wait_set Pointer to the rcl_wait_set_t that was using the
-   *   resulting guard condition.
-   * \throws anything rclcpp::exceptions::throw_from_rcl_error can throw.
-   * \throws std::runtime_error if a nonexistent wait set is trying to release sigint guard condition.
-   */
-  RCLCPP_PUBLIC
-  void
-  release_interrupt_guard_condition(rcl_wait_set_t * wait_set);
-
-  /// Nothrow version of release_interrupt_guard_condition(), logs to RCLCPP_ERROR instead.
-  RCLCPP_PUBLIC
-  void
-  release_interrupt_guard_condition(rcl_wait_set_t * wait_set, const std::nothrow_t &) noexcept;
-
-  /// Interrupt any blocking executors, or wait sets associated with this context.
-  RCLCPP_PUBLIC
-  virtual
-  void
-  interrupt_all_wait_sets();
-
   /// Return a singleton instance for the SubContext type, constructing one if necessary.
   template<typename SubContext, typename ... Args>
   std::shared_ptr<SubContext>
@@ -347,7 +286,7 @@ private:
 
   // This mutex is recursive so that the destructor can ensure atomicity
   // between is_initialized and shutdown.
-  std::recursive_mutex init_mutex_;
+  mutable std::recursive_mutex init_mutex_;
   std::shared_ptr<rcl_context_t> rcl_context_;
   rclcpp::InitOptions init_options_;
   std::string shutdown_reason_;
@@ -368,11 +307,6 @@ private:
   /// Mutex for protecting the global condition variable.
   std::mutex interrupt_mutex_;
 
-  /// Mutex to protect sigint_guard_cond_handles_.
-  std::mutex interrupt_guard_cond_handles_mutex_;
-  /// Guard conditions for interrupting of associated wait sets on interrupt_all_wait_sets().
-  std::unordered_map<rcl_wait_set_t *, rcl_guard_condition_t> interrupt_guard_cond_handles_;
-
   /// Keep shared ownership of global vector of weak contexts
   std::shared_ptr<WeakContextsWrapper> weak_contexts_;
 };

rclcpp/include/rclcpp/contexts/default_context.hpp

@@ -36,22 +36,6 @@ RCLCPP_PUBLIC
 DefaultContext::SharedPtr
 get_global_default_context();
 
-namespace default_context
-{
-
-using DefaultContext
-[[deprecated("use rclcpp::contexts::DefaultContext instead")]] = DefaultContext;
-
-[[deprecated("use rclcpp::contexts::get_global_default_context() instead")]]
-RCLCPP_PUBLIC
-inline
-DefaultContext::SharedPtr
-get_global_default_context()
-{
-  return rclcpp::contexts::get_global_default_context();
-}
-
-}  // namespace default_context
 }  // namespace contexts
 }  // namespace rclcpp
 

rclcpp/include/rclcpp/create_generic_publisher.hpp

@@ -0,0 +1,69 @@
+// Copyright 2020, Apex.AI 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__CREATE_GENERIC_PUBLISHER_HPP_
+#define RCLCPP__CREATE_GENERIC_PUBLISHER_HPP_
+
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "rclcpp/generic_publisher.hpp"
+#include "rclcpp/node_interfaces/node_topics_interface.hpp"
+#include "rclcpp/publisher_options.hpp"
+#include "rclcpp/qos.hpp"
+#include "rclcpp/typesupport_helpers.hpp"
+
+namespace rclcpp
+{
+
+/// Create and return a GenericPublisher.
+/**
+ * The returned pointer will never be empty, but this function can throw various exceptions, for
+ * instance when the message's package can not be found on the AMENT_PREFIX_PATH.
+ *
+ * \param topics_interface NodeTopicsInterface pointer used in parts of the setup
+ * \param topic_name Topic name
+ * \param topic_type Topic type
+ * \param qos %QoS settings
+ * \param options %Publisher options.
+ * Not all publisher options are currently respected, the only relevant options for this
+ * publisher are `event_callbacks`, `use_default_callbacks`, and `%callback_group`.
+ */
+template<typename AllocatorT = std::allocator<void>>
+std::shared_ptr<GenericPublisher> create_generic_publisher(
+  rclcpp::node_interfaces::NodeTopicsInterface::SharedPtr topics_interface,
+  const std::string & topic_name,
+  const std::string & topic_type,
+  const rclcpp::QoS & qos,
+  const rclcpp::PublisherOptionsWithAllocator<AllocatorT> & options = (
+    rclcpp::PublisherOptionsWithAllocator<AllocatorT>()
+  )
+)
+{
+  auto ts_lib = rclcpp::get_typesupport_library(topic_type, "rosidl_typesupport_cpp");
+  auto pub = std::make_shared<GenericPublisher>(
+    topics_interface->get_node_base_interface(),
+    std::move(ts_lib),
+    topic_name,
+    topic_type,
+    qos,
+    options);
+  topics_interface->add_publisher(pub, options.callback_group);
+  return pub;
+}
+
+}  // namespace rclcpp
+
+#endif  // RCLCPP__CREATE_GENERIC_PUBLISHER_HPP_

rclcpp/include/rclcpp/create_generic_subscription.hpp

@@ -0,0 +1,79 @@
+// Copyright 2020, Apex.AI 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__CREATE_GENERIC_SUBSCRIPTION_HPP_
+#define RCLCPP__CREATE_GENERIC_SUBSCRIPTION_HPP_
+
+#include <functional>
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "rcl/subscription.h"
+#include "rclcpp/generic_subscription.hpp"
+#include "rclcpp/node_interfaces/node_topics_interface.hpp"
+#include "rclcpp/qos.hpp"
+#include "rclcpp/serialized_message.hpp"
+#include "rclcpp/subscription_options.hpp"
+#include "rclcpp/typesupport_helpers.hpp"
+
+namespace rclcpp
+{
+
+/// Create and return a GenericSubscription.
+/**
+ * The returned pointer will never be empty, but this function can throw various exceptions, for
+ * instance when the message's package can not be found on the AMENT_PREFIX_PATH.
+ *
+ * \param topics_interface NodeTopicsInterface pointer used in parts of the setup.
+ * \param topic_name Topic name
+ * \param topic_type Topic type
+ * \param qos %QoS settings
+ * \param callback Callback for new messages of serialized form
+ * \param options %Publisher options.
+ * Not all publisher options are currently respected, the only relevant options for this
+ * publisher are `event_callbacks`, `use_default_callbacks`, and `%callback_group`.
+ */
+template<typename AllocatorT = std::allocator<void>>
+std::shared_ptr<GenericSubscription> create_generic_subscription(
+  rclcpp::node_interfaces::NodeTopicsInterface::SharedPtr topics_interface,
+  const std::string & topic_name,
+  const std::string & topic_type,
+  const rclcpp::QoS & qos,
+  std::function<void(std::shared_ptr<rclcpp::SerializedMessage>)> callback,
+  const rclcpp::SubscriptionOptionsWithAllocator<AllocatorT> & options = (
+    rclcpp::SubscriptionOptionsWithAllocator<AllocatorT>()
+  )
+)
+{
+  auto ts_lib = rclcpp::get_typesupport_library(
+    topic_type, "rosidl_typesupport_cpp");
+
+  auto subscription = std::make_shared<GenericSubscription>(
+    topics_interface->get_node_base_interface(),
+    std::move(ts_lib),
+    topic_name,
+    topic_type,
+    qos,
+    callback,
+    options);
+
+  topics_interface->add_subscription(subscription, options.callback_group);
+
+  return subscription;
+}
+
+}  // namespace rclcpp
+
+#endif  // RCLCPP__CREATE_GENERIC_SUBSCRIPTION_HPP_

rclcpp/include/rclcpp/create_publisher.hpp

@@ -17,6 +17,7 @@
 
 #include <memory>
 #include <string>
+#include <utility>
 
 #include "rclcpp/node_interfaces/get_node_topics_interface.hpp"
 #include "rclcpp/node_interfaces/node_topics_interface.hpp"
@@ -24,15 +25,65 @@
 #include "rclcpp/publisher_factory.hpp"
 #include "rclcpp/publisher_options.hpp"
 #include "rclcpp/qos.hpp"
+#include "rclcpp/qos_overriding_options.hpp"
+#include "rclcpp/detail/qos_parameters.hpp"
+
 #include "rmw/qos_profiles.h"
 
 namespace rclcpp
 {
 
+namespace detail
+{
+/// Create and return a publisher of the given MessageT type.
+template<
+  typename MessageT,
+  typename AllocatorT = std::allocator<void>,
+  typename PublisherT = rclcpp::Publisher<MessageT, AllocatorT>,
+  typename NodeParametersT,
+  typename NodeTopicsT>
+std::shared_ptr<PublisherT>
+create_publisher(
+  NodeParametersT & node_parameters,
+  NodeTopicsT & node_topics,
+  const std::string & topic_name,
+  const rclcpp::QoS & qos,
+  const rclcpp::PublisherOptionsWithAllocator<AllocatorT> & options = (
+    rclcpp::PublisherOptionsWithAllocator<AllocatorT>()
+  )
+)
+{
+  auto node_topics_interface = rclcpp::node_interfaces::get_node_topics_interface(node_topics);
+  const rclcpp::QoS & actual_qos = options.qos_overriding_options.get_policy_kinds().size() ?
+    rclcpp::detail::declare_qos_parameters(
+    options.qos_overriding_options, node_parameters,
+    node_topics_interface->resolve_topic_name(topic_name),
+    qos, rclcpp::detail::PublisherQosParametersTraits{}) :
+    qos;
+
+  // Create the publisher.
+  auto pub = node_topics_interface->create_publisher(
+    topic_name,
+    rclcpp::create_publisher_factory<MessageT, AllocatorT, PublisherT>(options),
+    actual_qos
+  );
+
+  // Add the publisher to the node topics interface.
+  node_topics_interface->add_publisher(pub, options.callback_group);
+
+  return std::dynamic_pointer_cast<PublisherT>(pub);
+}
+}  // namespace detail
+
+
 /// Create and return a publisher of the given MessageT type.
 /**
  * The NodeT type only needs to have a method called get_node_topics_interface()
  * which returns a shared_ptr to a NodeTopicsInterface.
+ *
+ * In case `options.qos_overriding_options` is enabling qos parameter overrides,
+ * NodeT must also have a method called get_node_parameters_interface()
+ * which returns a shared_ptr to a NodeParametersInterface.
  */
 template<
   typename MessageT,
@@ -49,21 +100,28 @@ create_publisher(
   )
 )
 {
-  // Extract the NodeTopicsInterface from the NodeT.
-  using rclcpp::node_interfaces::get_node_topics_interface;
-  auto node_topics = get_node_topics_interface(node);
+  return detail::create_publisher<MessageT, AllocatorT, PublisherT>(
+    node, node, topic_name, qos, options);
+}
 
-  // Create the publisher.
-  auto pub = node_topics->create_publisher(
-    topic_name,
-    rclcpp::create_publisher_factory<MessageT, AllocatorT, PublisherT>(options),
-    qos
-  );
-
-  // Add the publisher to the node topics interface.
-  node_topics->add_publisher(pub, options.callback_group);
-
-  return std::dynamic_pointer_cast<PublisherT>(pub);
+/// Create and return a publisher of the given MessageT type.
+template<
+  typename MessageT,
+  typename AllocatorT = std::allocator<void>,
+  typename PublisherT = rclcpp::Publisher<MessageT, AllocatorT>>
+std::shared_ptr<PublisherT>
+create_publisher(
+  rclcpp::node_interfaces::NodeParametersInterface::SharedPtr & node_parameters,
+  rclcpp::node_interfaces::NodeTopicsInterface::SharedPtr & node_topics,
+  const std::string & topic_name,
+  const rclcpp::QoS & qos,
+  const rclcpp::PublisherOptionsWithAllocator<AllocatorT> & options = (
+    rclcpp::PublisherOptionsWithAllocator<AllocatorT>()
+  )
+)
+{
+  return detail::create_publisher<MessageT, AllocatorT, PublisherT>(
+    node_parameters, node_topics, topic_name, qos, options);
 }
 
 }  // namespace rclcpp

rclcpp/include/rclcpp/create_subscription.hpp

@@ -41,12 +41,115 @@
 namespace rclcpp
 {
 
+namespace detail
+{
+template<
+  typename MessageT,
+  typename CallbackT,
+  typename AllocatorT,
+  typename CallbackMessageT,
+  typename SubscriptionT,
+  typename MessageMemoryStrategyT,
+  typename NodeParametersT,
+  typename NodeTopicsT>
+typename std::shared_ptr<SubscriptionT>
+create_subscription(
+  NodeParametersT & node_parameters,
+  NodeTopicsT & node_topics,
+  const std::string & topic_name,
+  const rclcpp::QoS & qos,
+  CallbackT && callback,
+  const rclcpp::SubscriptionOptionsWithAllocator<AllocatorT> & options = (
+    rclcpp::SubscriptionOptionsWithAllocator<AllocatorT>()
+  ),
+  typename MessageMemoryStrategyT::SharedPtr msg_mem_strat = (
+    MessageMemoryStrategyT::create_default()
+  )
+)
+{
+  using rclcpp::node_interfaces::get_node_topics_interface;
+  auto node_topics_interface = get_node_topics_interface(node_topics);
+
+  std::shared_ptr<rclcpp::topic_statistics::SubscriptionTopicStatistics<CallbackMessageT>>
+  subscription_topic_stats = nullptr;
+
+  if (rclcpp::detail::resolve_enable_topic_statistics(
+      options,
+      *node_topics_interface->get_node_base_interface()))
+  {
+    if (options.topic_stats_options.publish_period <= std::chrono::milliseconds(0)) {
+      throw std::invalid_argument(
+              "topic_stats_options.publish_period must be greater than 0, specified value of " +
+              std::to_string(options.topic_stats_options.publish_period.count()) +
+              " ms");
+    }
+
+    std::shared_ptr<Publisher<statistics_msgs::msg::MetricsMessage>>
+    publisher = rclcpp::detail::create_publisher<statistics_msgs::msg::MetricsMessage>(
+      node_parameters,
+      node_topics_interface,
+      options.topic_stats_options.publish_topic,
+      qos);
+
+    subscription_topic_stats = std::make_shared<
+      rclcpp::topic_statistics::SubscriptionTopicStatistics<CallbackMessageT>
+      >(node_topics_interface->get_node_base_interface()->get_name(), publisher);
+
+    std::weak_ptr<
+      rclcpp::topic_statistics::SubscriptionTopicStatistics<CallbackMessageT>
+    > weak_subscription_topic_stats(subscription_topic_stats);
+    auto sub_call_back = [weak_subscription_topic_stats]() {
+        auto subscription_topic_stats = weak_subscription_topic_stats.lock();
+        if (subscription_topic_stats) {
+          subscription_topic_stats->publish_message_and_reset_measurements();
+        }
+      };
+
+    auto node_timer_interface = node_topics_interface->get_node_timers_interface();
+
+    auto timer = create_wall_timer(
+      std::chrono::duration_cast<std::chrono::nanoseconds>(
+        options.topic_stats_options.publish_period),
+      sub_call_back,
+      options.callback_group,
+      node_topics_interface->get_node_base_interface(),
+      node_timer_interface
+    );
+
+    subscription_topic_stats->set_publisher_timer(timer);
+  }
+
+  auto factory = rclcpp::create_subscription_factory<MessageT>(
+    std::forward<CallbackT>(callback),
+    options,
+    msg_mem_strat,
+    subscription_topic_stats
+  );
+
+  const rclcpp::QoS & actual_qos = options.qos_overriding_options.get_policy_kinds().size() ?
+    rclcpp::detail::declare_qos_parameters(
+    options.qos_overriding_options, node_parameters,
+    node_topics_interface->resolve_topic_name(topic_name),
+    qos, rclcpp::detail::SubscriptionQosParametersTraits{}) :
+    qos;
+
+  auto sub = node_topics_interface->create_subscription(topic_name, factory, actual_qos);
+  node_topics_interface->add_subscription(sub, options.callback_group);
+
+  return std::dynamic_pointer_cast<SubscriptionT>(sub);
+}
+}  // namespace detail
+
 /// Create and return a subscription of the given MessageT type.
 /**
  * The NodeT type only needs to have a method called get_node_topics_interface()
  * which returns a shared_ptr to a NodeTopicsInterface, or be a
  * NodeTopicsInterface pointer itself.
  *
+ * In case `options.qos_overriding_options` is enabling qos parameter overrides,
+ * NodeT must also have a method called get_node_parameters_interface()
+ * which returns a shared_ptr to a NodeParametersInterface.
+ *
  * \tparam MessageT
  * \tparam CallbackT
  * \tparam AllocatorT
@@ -78,7 +181,7 @@ template<
   typename NodeT>
 typename std::shared_ptr<SubscriptionT>
 create_subscription(
-  NodeT && node,
+  NodeT & node,
   const std::string & topic_name,
   const rclcpp::QoS & qos,
   CallbackT && callback,
@@ -90,68 +193,45 @@ create_subscription(
   )
 )
 {
-  using rclcpp::node_interfaces::get_node_topics_interface;
-  auto node_topics = get_node_topics_interface(std::forward<NodeT>(node));
+  return rclcpp::detail::create_subscription<
+    MessageT, CallbackT, AllocatorT, CallbackMessageT, SubscriptionT, MessageMemoryStrategyT>(
+    node, node, topic_name, qos, std::forward<CallbackT>(callback), options, msg_mem_strat);
+}
 
-  std::shared_ptr<rclcpp::topic_statistics::SubscriptionTopicStatistics<CallbackMessageT>>
-  subscription_topic_stats = nullptr;
-
-  if (rclcpp::detail::resolve_enable_topic_statistics(
-      options,
-      *node_topics->get_node_base_interface()))
-  {
-    if (options.topic_stats_options.publish_period <= std::chrono::milliseconds(0)) {
-      throw std::invalid_argument(
-              "topic_stats_options.publish_period must be greater than 0, specified value of " +
-              std::to_string(options.topic_stats_options.publish_period.count()) +
-              " ms");
-    }
-
-    std::shared_ptr<Publisher<statistics_msgs::msg::MetricsMessage>> publisher =
-      create_publisher<statistics_msgs::msg::MetricsMessage>(
-      node,
-      options.topic_stats_options.publish_topic,
-      qos);
-
-    subscription_topic_stats = std::make_shared<
-      rclcpp::topic_statistics::SubscriptionTopicStatistics<CallbackMessageT>
-      >(node_topics->get_node_base_interface()->get_name(), publisher);
-
-    std::weak_ptr<
-      rclcpp::topic_statistics::SubscriptionTopicStatistics<CallbackMessageT>
-    > weak_subscription_topic_stats(subscription_topic_stats);
-    auto sub_call_back = [weak_subscription_topic_stats]() {
-        auto subscription_topic_stats = weak_subscription_topic_stats.lock();
-        if (subscription_topic_stats) {
-          subscription_topic_stats->publish_message();
-        }
-      };
-
-    auto node_timer_interface = node_topics->get_node_timers_interface();
-
-    auto timer = create_wall_timer(
-      std::chrono::duration_cast<std::chrono::nanoseconds>(
-        options.topic_stats_options.publish_period),
-      sub_call_back,
-      options.callback_group,
-      node_topics->get_node_base_interface(),
-      node_timer_interface
-    );
-
-    subscription_topic_stats->set_publisher_timer(timer);
-  }
-
-  auto factory = rclcpp::create_subscription_factory<MessageT>(
-    std::forward<CallbackT>(callback),
-    options,
-    msg_mem_strat,
-    subscription_topic_stats
-  );
-
-  auto sub = node_topics->create_subscription(topic_name, factory, qos);
-  node_topics->add_subscription(sub, options.callback_group);
-
-  return std::dynamic_pointer_cast<SubscriptionT>(sub);
+/// Create and return a subscription of the given MessageT type.
+/**
+ * See \ref create_subscription().
+ */
+template<
+  typename MessageT,
+  typename CallbackT,
+  typename AllocatorT = std::allocator<void>,
+  typename CallbackMessageT =
+  typename rclcpp::subscription_traits::has_message_type<CallbackT>::type,
+  typename SubscriptionT = rclcpp::Subscription<CallbackMessageT, AllocatorT>,
+  typename MessageMemoryStrategyT = rclcpp::message_memory_strategy::MessageMemoryStrategy<
+    CallbackMessageT,
+    AllocatorT
+  >>
+typename std::shared_ptr<SubscriptionT>
+create_subscription(
+  rclcpp::node_interfaces::NodeParametersInterface::SharedPtr & node_parameters,
+  rclcpp::node_interfaces::NodeTopicsInterface::SharedPtr & node_topics,
+  const std::string & topic_name,
+  const rclcpp::QoS & qos,
+  CallbackT && callback,
+  const rclcpp::SubscriptionOptionsWithAllocator<AllocatorT> & options = (
+    rclcpp::SubscriptionOptionsWithAllocator<AllocatorT>()
+  ),
+  typename MessageMemoryStrategyT::SharedPtr msg_mem_strat = (
+    MessageMemoryStrategyT::create_default()
+  )
+)
+{
+  return rclcpp::detail::create_subscription<
+    MessageT, CallbackT, AllocatorT, CallbackMessageT, SubscriptionT, MessageMemoryStrategyT>(
+    node_parameters, node_topics, topic_name, qos,
+    std::forward<CallbackT>(callback), options, msg_mem_strat);
 }
 
 }  // namespace rclcpp

rclcpp/include/rclcpp/detail/mutex_two_priorities.hpp

@@ -0,0 +1,76 @@
+// Copyright 2021 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__MUTEX_TWO_PRIORITIES_HPP_
+#define RCLCPP__DETAIL__MUTEX_TWO_PRIORITIES_HPP_
+
+#include <condition_variable>
+#include <mutex>
+
+namespace rclcpp
+{
+namespace detail
+{
+/// \internal A mutex that has two locking mechanism, one with higher priority than the other.
+/**
+ * After the current mutex owner release the lock, a thread that used the high
+ * priority mechanism will have priority over threads that used the low priority mechanism.
+ */
+class MutexTwoPriorities
+{
+public:
+  class HighPriorityLockable
+  {
+public:
+    explicit HighPriorityLockable(MutexTwoPriorities & parent);
+
+    void lock();
+
+    void unlock();
+
+private:
+    MutexTwoPriorities & parent_;
+  };
+
+  class LowPriorityLockable
+  {
+public:
+    explicit LowPriorityLockable(MutexTwoPriorities & parent);
+
+    void lock();
+
+    void unlock();
+
+private:
+    MutexTwoPriorities & parent_;
+  };
+
+  HighPriorityLockable
+  get_high_priority_lockable();
+
+  LowPriorityLockable
+  get_low_priority_lockable();
+
+private:
+  std::condition_variable hp_cv_;
+  std::condition_variable lp_cv_;
+  std::mutex cv_mutex_;
+  size_t hp_waiting_count_{0u};
+  bool data_taken_{false};
+};
+
+}  // namespace detail
+}  // namespace rclcpp
+
+#endif  // RCLCPP__DETAIL__MUTEX_TWO_PRIORITIES_HPP_

rclcpp/include/rclcpp/detail/qos_parameters.hpp

@@ -0,0 +1,326 @@
+// Copyright 2020 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__DETAIL__QOS_PARAMETERS_HPP_
+#define RCLCPP__DETAIL__QOS_PARAMETERS_HPP_
+
+#include <algorithm>
+#include <array>
+#include <functional>
+#include <initializer_list>
+#include <map>
+#include <string>
+#include <type_traits>
+#include <vector>
+
+#include "rcl_interfaces/msg/parameter_descriptor.hpp"
+#include "rcpputils/pointer_traits.hpp"
+#include "rmw/qos_string_conversions.h"
+
+#include "rclcpp/duration.hpp"
+#include "rclcpp/node_interfaces/get_node_parameters_interface.hpp"
+#include "rclcpp/node_interfaces/node_parameters_interface.hpp"
+#include "rclcpp/qos_overriding_options.hpp"
+
+namespace rclcpp
+{
+namespace detail
+{
+
+/// \internal Trait used to specialize `declare_qos_parameters()` for publishers.
+struct PublisherQosParametersTraits
+{
+  static constexpr const char * entity_type() {return "publisher";}
+  static constexpr auto allowed_policies()
+  {
+    return std::array<::rclcpp::QosPolicyKind, 9> {
+      QosPolicyKind::AvoidRosNamespaceConventions,
+      QosPolicyKind::Deadline,
+      QosPolicyKind::Durability,
+      QosPolicyKind::History,
+      QosPolicyKind::Depth,
+      QosPolicyKind::Lifespan,
+      QosPolicyKind::Liveliness,
+      QosPolicyKind::LivelinessLeaseDuration,
+      QosPolicyKind::Reliability,
+    };
+  }
+};
+
+/// \internal Trait used to specialize `declare_qos_parameters()` for subscriptions.
+struct SubscriptionQosParametersTraits
+{
+  static constexpr const char * entity_type() {return "subscription";}
+  static constexpr auto allowed_policies()
+  {
+    return std::array<::rclcpp::QosPolicyKind, 8> {
+      QosPolicyKind::AvoidRosNamespaceConventions,
+      QosPolicyKind::Deadline,
+      QosPolicyKind::Durability,
+      QosPolicyKind::History,
+      QosPolicyKind::Depth,
+      QosPolicyKind::Liveliness,
+      QosPolicyKind::LivelinessLeaseDuration,
+      QosPolicyKind::Reliability,
+    };
+  }
+};
+
+/// \internal Returns the given `policy` of the profile `qos` converted to a parameter value.
+inline
+::rclcpp::ParameterValue
+get_default_qos_param_value(rclcpp::QosPolicyKind policy, const rclcpp::QoS & qos);
+
+/// \internal Modify the given `policy` in `qos` to be `value`.
+inline
+void
+apply_qos_override(
+  rclcpp::QosPolicyKind policy, rclcpp::ParameterValue value, rclcpp::QoS & qos);
+
+inline
+rclcpp::ParameterValue
+declare_parameter_or_get(
+  rclcpp::node_interfaces::NodeParametersInterface & parameters_interface,
+  const std::string & param_name,
+  rclcpp::ParameterValue param_value,
+  rcl_interfaces::msg::ParameterDescriptor descriptor)
+{
+  try {
+    return parameters_interface.declare_parameter(
+      param_name, param_value, descriptor);
+  } catch (const rclcpp::exceptions::ParameterAlreadyDeclaredException &) {
+    return parameters_interface.get_parameter(param_name).get_parameter_value();
+  }
+}
+
+/// \internal Declare QoS parameters for the given entity.
+/**
+ * \tparam NodeT Node pointer or reference type.
+ * \tparam EntityQosParametersTraits A class with two static methods: `entity_type()` and
+ *  `allowed_policies()`. See `PublisherQosParametersTraits` and `SubscriptionQosParametersTraits`.
+ * \param options User provided options that indicate if QoS parameter overrides should be
+ *  declared or not, which policy can have overrides, and optionally a callback to validate the profile.
+ * \param node Parameters will be declared using this node.
+ * \param topic_name Name of the topic of the entity.
+ * \param default_qos User provided qos. It will be used as a default for the parameters declared.
+ * \return qos profile based on the user provided parameter overrides.
+ */
+template<typename NodeT, typename EntityQosParametersTraits>
+std::enable_if_t<
+  rclcpp::node_interfaces::has_node_parameters_interface<
+    decltype(std::declval<typename rcpputils::remove_pointer<NodeT>::type>())>::value ||
+  std::is_same<typename std::decay_t<NodeT>,
+  rclcpp::node_interfaces::NodeParametersInterface::SharedPtr>::value,
+  rclcpp::QoS>
+declare_qos_parameters(
+  const ::rclcpp::QosOverridingOptions & options,
+  NodeT & node,
+  const std::string & topic_name,
+  const ::rclcpp::QoS & default_qos,
+  EntityQosParametersTraits)
+{
+  auto & parameters_interface = *rclcpp::node_interfaces::get_node_parameters_interface(node);
+  std::string param_prefix;
+  const auto & id = options.get_id();
+  {
+    std::ostringstream oss{"qos_overrides.", std::ios::ate};
+    oss << topic_name << "." << EntityQosParametersTraits::entity_type();
+    if (!id.empty()) {
+      oss << "_" << id;
+    }
+    oss << ".";
+    param_prefix = oss.str();
+  }
+  std::string param_description_suffix;
+  {
+    std::ostringstream oss{"} for ", std::ios::ate};
+    oss << EntityQosParametersTraits::entity_type() << " {" << topic_name << "}";
+    if (!id.empty()) {
+      oss << " with id {" << id << "}";
+    }
+    param_description_suffix = oss.str();
+  }
+  rclcpp::QoS qos = default_qos;
+  for (auto policy : EntityQosParametersTraits::allowed_policies()) {
+    if (
+      std::count(options.get_policy_kinds().begin(), options.get_policy_kinds().end(), policy))
+    {
+      std::ostringstream param_name{param_prefix, std::ios::ate};
+      param_name << qos_policy_kind_to_cstr(policy);
+      std::ostringstream param_desciption{"qos policy {", std::ios::ate};
+      param_desciption << qos_policy_kind_to_cstr(policy) << param_description_suffix;
+      rcl_interfaces::msg::ParameterDescriptor descriptor{};
+      descriptor.description = param_desciption.str();
+      descriptor.read_only = true;
+      auto value = declare_parameter_or_get(
+        parameters_interface, param_name.str(),
+        get_default_qos_param_value(policy, qos), descriptor);
+      ::rclcpp::detail::apply_qos_override(policy, value, qos);
+    }
+  }
+  const auto & validation_callback = options.get_validation_callback();
+  if (validation_callback) {
+    auto result = validation_callback(qos);
+    if (!result.successful) {
+      throw rclcpp::exceptions::InvalidQosOverridesException{
+              "validation callback failed: " + result.reason};
+    }
+  }
+  return qos;
+}
+
+// TODO(ivanpauno): This overload cannot declare the QoS parameters, as a node parameters interface
+// was not provided.
+template<typename NodeT, typename EntityQosParametersTraits>
+std::enable_if_t<
+  !(rclcpp::node_interfaces::has_node_parameters_interface<
+    decltype(std::declval<typename rcpputils::remove_pointer<NodeT>::type>())>::value ||
+  std::is_same<typename std::decay_t<NodeT>,
+  rclcpp::node_interfaces::NodeParametersInterface::SharedPtr>::value),
+  rclcpp::QoS>
+declare_qos_parameters(
+  const ::rclcpp::QosOverridingOptions & options,
+  NodeT &,
+  const std::string &,
+  const ::rclcpp::QoS & default_qos,
+  EntityQosParametersTraits)
+{
+  if (options.get_policy_kinds().size()) {
+    std::runtime_error exc{
+      "passed non-default qos overriding options without providing a parameters interface"};
+    throw exc;
+  }
+  return default_qos;
+}
+
+/// \internal Helper function to get a rmw qos policy value from a string.
+#define RCLCPP_DETAIL_APPLY_QOS_OVERRIDE_FROM_PARAMETER_STRING( \
+    kind_lower, kind_upper, parameter_value, rclcpp_qos) \
+  do { \
+    auto policy_string = (parameter_value).get<std::string>(); \
+    auto policy_value = rmw_qos_ ## kind_lower ## _policy_from_str(policy_string.c_str()); \
+    if (RMW_QOS_POLICY_ ## kind_upper ## _UNKNOWN == policy_value) { \
+      throw std::invalid_argument{"unknown QoS policy " #kind_lower " value: " + policy_string}; \
+    } \
+    ((rclcpp_qos).kind_lower)(policy_value); \
+  } while (0)
+
+inline
+void
+apply_qos_override(
+  rclcpp::QosPolicyKind policy, rclcpp::ParameterValue value, rclcpp::QoS & qos)
+{
+  switch (policy) {
+    case QosPolicyKind::AvoidRosNamespaceConventions:
+      qos.avoid_ros_namespace_conventions(value.get<bool>());
+      break;
+    case QosPolicyKind::Deadline:
+      qos.deadline(::rclcpp::Duration::from_nanoseconds(value.get<int64_t>()));
+      break;
+    case QosPolicyKind::Durability:
+      RCLCPP_DETAIL_APPLY_QOS_OVERRIDE_FROM_PARAMETER_STRING(
+        durability, DURABILITY, value, qos);
+      break;
+    case QosPolicyKind::History:
+      RCLCPP_DETAIL_APPLY_QOS_OVERRIDE_FROM_PARAMETER_STRING(
+        history, HISTORY, value, qos);
+      break;
+    case QosPolicyKind::Depth:
+      qos.get_rmw_qos_profile().depth = static_cast<size_t>(value.get<int64_t>());
+      break;
+    case QosPolicyKind::Lifespan:
+      qos.lifespan(::rclcpp::Duration::from_nanoseconds(value.get<int64_t>()));
+      break;
+    case QosPolicyKind::Liveliness:
+      RCLCPP_DETAIL_APPLY_QOS_OVERRIDE_FROM_PARAMETER_STRING(
+        liveliness, LIVELINESS, value, qos);
+      break;
+    case QosPolicyKind::LivelinessLeaseDuration:
+      qos.liveliness_lease_duration(::rclcpp::Duration::from_nanoseconds(value.get<int64_t>()));
+      break;
+    case QosPolicyKind::Reliability:
+      RCLCPP_DETAIL_APPLY_QOS_OVERRIDE_FROM_PARAMETER_STRING(
+        reliability, RELIABILITY, value, qos);
+      break;
+    default:
+      throw std::invalid_argument{"unknown QosPolicyKind"};
+  }
+}
+
+/// Convert `rmw_time_t` to `int64_t` that can be used as a parameter value.
+inline
+int64_t
+rmw_duration_to_int64_t(rmw_time_t rmw_duration)
+{
+  return ::rclcpp::Duration(
+    static_cast<int32_t>(rmw_duration.sec),
+    static_cast<uint32_t>(rmw_duration.nsec)
+  ).nanoseconds();
+}
+
+/// \internal Throw an exception if `policy_value_stringified` is NULL.
+inline
+const char *
+check_if_stringified_policy_is_null(const char * policy_value_stringified, QosPolicyKind kind)
+{
+  if (!policy_value_stringified) {
+    std::ostringstream oss{"unknown value for policy kind {", std::ios::ate};
+    oss << kind << "}";
+    throw std::invalid_argument{oss.str()};
+  }
+  return policy_value_stringified;
+}
+
+inline
+::rclcpp::ParameterValue
+get_default_qos_param_value(rclcpp::QosPolicyKind kind, const rclcpp::QoS & qos)
+{
+  using ParameterValue = ::rclcpp::ParameterValue;
+  const auto & rmw_qos = qos.get_rmw_qos_profile();
+  switch (kind) {
+    case QosPolicyKind::AvoidRosNamespaceConventions:
+      return ParameterValue(rmw_qos.avoid_ros_namespace_conventions);
+    case QosPolicyKind::Deadline:
+      return ParameterValue(rmw_duration_to_int64_t(rmw_qos.deadline));
+    case QosPolicyKind::Durability:
+      return ParameterValue(
+        check_if_stringified_policy_is_null(
+          rmw_qos_durability_policy_to_str(rmw_qos.durability), kind));
+    case QosPolicyKind::History:
+      return ParameterValue(
+        check_if_stringified_policy_is_null(
+          rmw_qos_history_policy_to_str(rmw_qos.history), kind));
+    case QosPolicyKind::Depth:
+      return ParameterValue(static_cast<int64_t>(rmw_qos.depth));
+    case QosPolicyKind::Lifespan:
+      return ParameterValue(rmw_duration_to_int64_t(rmw_qos.lifespan));
+    case QosPolicyKind::Liveliness:
+      return ParameterValue(
+        check_if_stringified_policy_is_null(
+          rmw_qos_liveliness_policy_to_str(rmw_qos.liveliness), kind));
+    case QosPolicyKind::LivelinessLeaseDuration:
+      return ParameterValue(rmw_duration_to_int64_t(rmw_qos.liveliness_lease_duration));
+    case QosPolicyKind::Reliability:
+      return ParameterValue(
+        check_if_stringified_policy_is_null(
+          rmw_qos_reliability_policy_to_str(rmw_qos.reliability), kind));
+    default:
+      throw std::invalid_argument{"unknown QoS policy kind"};
+  }
+}
+
+}  // namespace detail
+}  // namespace rclcpp
+
+#endif  // RCLCPP__DETAIL__QOS_PARAMETERS_HPP_

rclcpp/include/rclcpp/detail/subscription_callback_type_helper.hpp

@@ -0,0 +1,164 @@
+// Copyright 2021 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__SUBSCRIPTION_CALLBACK_TYPE_HELPER_HPP_
+#define RCLCPP__DETAIL__SUBSCRIPTION_CALLBACK_TYPE_HELPER_HPP_
+
+#include <memory>
+#include <type_traits>
+
+#include "rclcpp/function_traits.hpp"
+#include "rclcpp/message_info.hpp"
+
+namespace rclcpp
+{
+namespace detail
+{
+
+/// Template metaprogramming helper used to resolve the callback argument into a std::function.
+/**
+ * Sometimes the CallbackT is a std::function already, but it could also be a
+ * function pointer, lambda, bind, or some variant of those.
+ * In some cases, like a lambda where the arguments can be converted between one
+ * another, e.g. std::function<void (shared_ptr<...>)> and
+ * std::function<void (unique_ptr<...>)>, you need to make that not ambiguous
+ * by checking the arguments independently using function traits rather than
+ * rely on overloading the two std::function types.
+ *
+ * This issue, with the lambda's, can be demonstrated with this minimal program:
+ *
+ *   #include <functional>
+ *   #include <memory>
+ *
+ *   void f(std::function<void (std::shared_ptr<int>)>) {}
+ *   void f(std::function<void (std::unique_ptr<int>)>) {}
+ *
+ *   int main() {
+ *     // Fails to compile with an "ambiguous call" error.
+ *     f([](std::shared_ptr<int>){});
+ *
+ *     // Works.
+ *     std::function<void (std::shared_ptr<int>)> cb = [](std::shared_ptr<int>){};
+ *     f(cb);
+ *   }
+ *
+ * If this program ever starts working in a future version of C++, this class
+ * may become redundant.
+ *
+ * This helper works by using SFINAE with rclcpp::function_traits::same_arguments<>
+ * to narrow down the exact std::function<> type for the given CallbackT.
+ */
+template<typename MessageT, typename CallbackT, typename Enable = void>
+struct SubscriptionCallbackTypeHelper
+{
+  using callback_type = typename rclcpp::function_traits::as_std_function<CallbackT>::type;
+};
+
+template<typename MessageT, typename CallbackT>
+struct SubscriptionCallbackTypeHelper<
+  MessageT,
+  CallbackT,
+  typename std::enable_if_t<
+    rclcpp::function_traits::same_arguments<
+      CallbackT,
+      std::function<void(std::shared_ptr<const MessageT>)>
+    >::value
+  >
+>
+{
+  using callback_type = std::function<void (std::shared_ptr<const MessageT>)>;
+};
+
+template<typename MessageT, typename CallbackT>
+struct SubscriptionCallbackTypeHelper<
+  MessageT,
+  CallbackT,
+  typename std::enable_if_t<
+    rclcpp::function_traits::same_arguments<
+      CallbackT,
+      std::function<void(std::shared_ptr<const MessageT>, const rclcpp::MessageInfo &)>
+    >::value
+  >
+>
+{
+  using callback_type =
+    std::function<void (std::shared_ptr<const MessageT>, const rclcpp::MessageInfo &)>;
+};
+
+template<typename MessageT, typename CallbackT>
+struct SubscriptionCallbackTypeHelper<
+  MessageT,
+  CallbackT,
+  typename std::enable_if_t<
+    rclcpp::function_traits::same_arguments<
+      CallbackT,
+      std::function<void(const std::shared_ptr<const MessageT> &)>
+    >::value
+  >
+>
+{
+  using callback_type = std::function<void (const std::shared_ptr<const MessageT> &)>;
+};
+
+template<typename MessageT, typename CallbackT>
+struct SubscriptionCallbackTypeHelper<
+  MessageT,
+  CallbackT,
+  typename std::enable_if_t<
+    rclcpp::function_traits::same_arguments<
+      CallbackT,
+      std::function<void(const std::shared_ptr<const MessageT> &, const rclcpp::MessageInfo &)>
+    >::value
+  >
+>
+{
+  using callback_type =
+    std::function<void (const std::shared_ptr<const MessageT> &, const rclcpp::MessageInfo &)>;
+};
+
+template<typename MessageT, typename CallbackT>
+struct SubscriptionCallbackTypeHelper<
+  MessageT,
+  CallbackT,
+  typename std::enable_if_t<
+    rclcpp::function_traits::same_arguments<
+      CallbackT,
+      std::function<void(std::shared_ptr<MessageT>)>
+    >::value
+  >
+>
+{
+  using callback_type = std::function<void (std::shared_ptr<MessageT>)>;
+};
+
+template<typename MessageT, typename CallbackT>
+struct SubscriptionCallbackTypeHelper<
+  MessageT,
+  CallbackT,
+  typename std::enable_if_t<
+    rclcpp::function_traits::same_arguments<
+      CallbackT,
+      std::function<void(std::shared_ptr<MessageT>, const rclcpp::MessageInfo &)>
+    >::value
+  >
+>
+{
+  using callback_type =
+    std::function<void (std::shared_ptr<MessageT>, const rclcpp::MessageInfo &)>;
+};
+
+}  // namespace detail
+}  // namespace rclcpp
+
+#endif  // RCLCPP__DETAIL__SUBSCRIPTION_CALLBACK_TYPE_HELPER_HPP_

rclcpp/include/rclcpp/duration.hpp

@@ -38,10 +38,14 @@ public:
    */
   Duration(int32_t seconds, uint32_t nanoseconds);
 
-  // This constructor matches any numeric value - ints or floats.
+  /// Construct duration from the specified nanoseconds.
+  [[deprecated(
+    "Use Duration::from_nanoseconds instead or std::chrono_literals. For example:"
+    "rclcpp::Duration::from_nanoseconds(int64_variable);"
+    "rclcpp::Duration(0ns);")]]
   explicit Duration(rcl_duration_value_t nanoseconds);
 
-  // This constructor matches std::chrono::nanoseconds.
+  /// Construct duration from the specified std::chrono::nanoseconds.
   explicit Duration(std::chrono::nanoseconds nanoseconds);
 
   // This constructor matches any std::chrono value other than nanoseconds
@@ -129,6 +133,13 @@ public:
   static Duration
   from_seconds(double seconds);
 
+  /// Create a duration object from an integer number representing nanoseconds
+  static Duration
+  from_nanoseconds(rcl_duration_value_t nanoseconds);
+
+  static Duration
+  from_rmw_time(rmw_time_t duration);
+
   /// Convert Duration into a std::chrono::Duration.
   template<class DurationT>
   DurationT
@@ -143,6 +154,8 @@ public:
 
 private:
   rcl_duration_t rcl_duration_;
+
+  Duration() = default;
 };
 
 }  // namespace rclcpp

rclcpp/include/rclcpp/exceptions/exceptions.hpp

@@ -282,6 +282,34 @@ class ParameterModifiedInCallbackException : public std::runtime_error
   using std::runtime_error::runtime_error;
 };
 
+/// Thrown when a parameter override wasn't provided and one was required.
+class NoParameterOverrideProvided : public std::runtime_error
+{
+public:
+  /// Construct an instance.
+  /**
+   * \param[in] name the name of the parameter.
+   * \param[in] message custom exception message.
+   */
+  explicit NoParameterOverrideProvided(const std::string & name)
+  : std::runtime_error("parameter '" + name + "' requires an user provided parameter override")
+  {}
+};
+
+/// Thrown if the QoS overrides provided aren't valid.
+class InvalidQosOverridesException : public std::runtime_error
+{
+  // Inherit constructors from runtime_error.
+  using std::runtime_error::runtime_error;
+};
+
+/// Thrown if a QoS compatibility check fails.
+class QoSCheckCompatibleException : public std::runtime_error
+{
+  // Inherit constructors from runtime_error.
+  using std::runtime_error::runtime_error;
+};
+
 }  // namespace exceptions
 }  // namespace rclcpp
 

rclcpp/include/rclcpp/executor.hpp

@@ -31,6 +31,7 @@
 #include "rcl/wait.h"
 
 #include "rclcpp/contexts/default_context.hpp"
+#include "rclcpp/guard_condition.hpp"
 #include "rclcpp/executor_options.hpp"
 #include "rclcpp/future_return_code.hpp"
 #include "rclcpp/memory_strategies.hpp"
@@ -447,7 +448,7 @@ protected:
   RCLCPP_PUBLIC
   rclcpp::node_interfaces::NodeBaseInterface::SharedPtr
   get_node_by_group(
-    WeakCallbackGroupsToNodesMap weak_groups_to_nodes,
+    const WeakCallbackGroupsToNodesMap & weak_groups_to_nodes,
     rclcpp::CallbackGroup::SharedPtr group);
 
   /// Return true if the node has been added to this executor.
@@ -459,7 +460,7 @@ protected:
   bool
   has_node(
     const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-    WeakCallbackGroupsToNodesMap weak_groups_to_nodes) const;
+    const WeakCallbackGroupsToNodesMap & weak_groups_to_nodes) const;
 
   RCLCPP_PUBLIC
   rclcpp::CallbackGroup::SharedPtr
@@ -475,7 +476,7 @@ protected:
     rclcpp::CallbackGroup::SharedPtr group_ptr,
     rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
     WeakCallbackGroupsToNodesMap & weak_groups_to_nodes,
-    bool notify = true);
+    bool notify = true) RCPPUTILS_TSA_REQUIRES(mutex_);
 
   /// Remove a callback group from the executor.
   /**
@@ -486,7 +487,7 @@ protected:
   remove_callback_group_from_map(
     rclcpp::CallbackGroup::SharedPtr group_ptr,
     WeakCallbackGroupsToNodesMap & weak_groups_to_nodes,
-    bool notify = true);
+    bool notify = true) RCPPUTILS_TSA_REQUIRES(mutex_);
 
   RCLCPP_PUBLIC
   bool
@@ -496,7 +497,7 @@ protected:
   bool
   get_next_ready_executable_from_map(
     AnyExecutable & any_executable,
-    WeakCallbackGroupsToNodesMap weak_groups_to_nodes);
+    const WeakCallbackGroupsToNodesMap & weak_groups_to_nodes);
 
   RCLCPP_PUBLIC
   bool
@@ -517,7 +518,7 @@ protected:
    */
   RCLCPP_PUBLIC
   virtual void
-  add_callback_groups_from_nodes_associated_to_executor();
+  add_callback_groups_from_nodes_associated_to_executor() RCPPUTILS_TSA_REQUIRES(mutex_);
 
   /// Spinning state, used to prevent multi threaded calls to spin and to cancel blocking spins.
   std::atomic_bool spinning;
@@ -525,14 +526,17 @@ protected:
   /// Guard condition for signaling the rmw layer to wake up for special events.
   rcl_guard_condition_t interrupt_guard_condition_ = rcl_get_zero_initialized_guard_condition();
 
+  std::shared_ptr<rclcpp::GuardCondition> shutdown_guard_condition_;
+
   /// Wait set for managing entities that the rmw layer waits on.
   rcl_wait_set_t wait_set_ = rcl_get_zero_initialized_wait_set();
 
   // Mutex to protect the subsequent memory_strategy_.
-  std::mutex memory_strategy_mutex_;
+  mutable std::mutex mutex_;
 
   /// The memory strategy: an interface for handling user-defined memory allocation strategies.
-  memory_strategy::MemoryStrategy::SharedPtr memory_strategy_;
+  memory_strategy::MemoryStrategy::SharedPtr
+  memory_strategy_ RCPPUTILS_TSA_PT_GUARDED_BY(mutex_);
 
   /// The context associated with this executor.
   std::shared_ptr<rclcpp::Context> context_;
@@ -540,7 +544,7 @@ protected:
   RCLCPP_DISABLE_COPY(Executor)
 
   RCLCPP_PUBLIC
-  void
+  virtual void
   spin_once_impl(std::chrono::nanoseconds timeout);
 
   typedef std::map<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr,
@@ -549,27 +553,26 @@ protected:
     WeakNodesToGuardConditionsMap;
 
   /// maps nodes to guard conditions
-  WeakNodesToGuardConditionsMap weak_nodes_to_guard_conditions_;
+  WeakNodesToGuardConditionsMap
+  weak_nodes_to_guard_conditions_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
 
   /// maps callback groups associated to nodes
-  WeakCallbackGroupsToNodesMap weak_groups_associated_with_executor_to_nodes_;
+  WeakCallbackGroupsToNodesMap
+  weak_groups_associated_with_executor_to_nodes_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
 
   /// maps callback groups to nodes associated with executor
-  WeakCallbackGroupsToNodesMap weak_groups_to_nodes_associated_with_executor_;
+  WeakCallbackGroupsToNodesMap
+  weak_groups_to_nodes_associated_with_executor_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
 
   /// maps all callback groups to nodes
-  WeakCallbackGroupsToNodesMap weak_groups_to_nodes_;
+  WeakCallbackGroupsToNodesMap
+  weak_groups_to_nodes_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
 
   /// nodes that are associated with the executor
-  std::list<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr> weak_nodes_;
+  std::list<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr>
+  weak_nodes_ RCPPUTILS_TSA_GUARDED_BY(mutex_);
 };
 
-namespace executor
-{
-
-using Executor [[deprecated("use rclcpp::Executor instead")]] = rclcpp::Executor;
-
-}  // namespace executor
 }  // namespace rclcpp
 
 #endif  // RCLCPP__EXECUTOR_HPP_

rclcpp/include/rclcpp/executor_options.hpp

@@ -38,20 +38,6 @@ struct ExecutorOptions
   size_t max_conditions;
 };
 
-namespace executor
-{
-
-using ExecutorArgs [[deprecated("use rclcpp::ExecutorOptions instead")]] = ExecutorOptions;
-
-[[deprecated("use rclcpp::ExecutorOptions() instead")]]
-inline
-rclcpp::ExecutorOptions
-create_default_executor_arguments()
-{
-  return rclcpp::ExecutorOptions();
-}
-
-}  // namespace executor
 }  // namespace rclcpp
 
 #endif  // RCLCPP__EXECUTOR_OPTIONS_HPP_

rclcpp/include/rclcpp/executors/multi_threaded_executor.hpp

@@ -22,6 +22,7 @@
 #include <thread>
 #include <unordered_map>
 
+#include "rclcpp/detail/mutex_two_priorities.hpp"
 #include "rclcpp/executor.hpp"
 #include "rclcpp/macros.hpp"
 #include "rclcpp/memory_strategies.hpp"
@@ -81,7 +82,7 @@ protected:
 private:
   RCLCPP_DISABLE_COPY(MultiThreadedExecutor)
 
-  std::mutex wait_mutex_;
+  detail::MutexTwoPriorities wait_mutex_;
   size_t number_of_threads_;
   bool yield_before_execute_;
   std::chrono::nanoseconds next_exec_timeout_;

rclcpp/include/rclcpp/executors/static_executor_entities_collector.hpp

@@ -69,12 +69,26 @@ public:
 
   /// Finalize StaticExecutorEntitiesCollector to clear resources
   RCLCPP_PUBLIC
-  void
-  fini();
+  bool
+  is_init() {return initialized_;}
 
   RCLCPP_PUBLIC
   void
-  execute() override;
+  fini();
+
+  /// Execute the waitable.
+  RCLCPP_PUBLIC
+  void
+  execute(std::shared_ptr<void> & data) override;
+
+  /// Take the data so that it can be consumed with `execute`.
+  /**
+   * For `StaticExecutorEntitiesCollector`, this always return `nullptr`.
+   * \sa rclcpp::Waitable::take_data()
+   */
+  RCLCPP_PUBLIC
+  std::shared_ptr<void>
+  take_data() override;
 
   /// Function to add_handles_to_wait_set and wait for work and
   /**
@@ -329,6 +343,9 @@ private:
 
   /// Executable list: timers, subscribers, clients, services and waitables
   rclcpp::experimental::ExecutableList exec_list_;
+
+  /// Bool to check if the entities collector has been initialized
+  bool initialized_ = false;
 };
 
 }  // namespace executors

rclcpp/include/rclcpp/executors/static_single_threaded_executor.hpp

@@ -15,6 +15,7 @@
 #ifndef RCLCPP__EXECUTORS__STATIC_SINGLE_THREADED_EXECUTOR_HPP_
 #define RCLCPP__EXECUTORS__STATIC_SINGLE_THREADED_EXECUTOR_HPP_
 
+#include <chrono>
 #include <cassert>
 #include <cstdlib>
 #include <memory>
@@ -78,6 +79,42 @@ public:
   void
   spin() override;
 
+  /// Static executor implementation of spin some
+  /**
+   * This non-blocking function will execute entities that
+   * were ready when this API was called, until timeout or no
+   * more work available. Entities that got ready while
+   * executing work, won't be taken into account here.
+   *
+   * Example:
+   *   while(condition) {
+   *     spin_some();
+   *     sleep(); // User should have some sync work or
+   *              // sleep to avoid a 100% CPU usage
+   *   }
+   */
+  RCLCPP_PUBLIC
+  void
+  spin_some(std::chrono::nanoseconds max_duration = std::chrono::nanoseconds(0)) override;
+
+  /// Static executor implementation of spin all
+  /**
+   * This non-blocking function will execute entities until
+   * timeout or no more work available. If new entities get ready
+   * while executing work available, they will be executed
+   * as long as the timeout hasn't expired.
+   *
+   * Example:
+   *   while(condition) {
+   *     spin_all();
+   *     sleep(); // User should have some sync work or
+   *              // sleep to avoid a 100% CPU usage
+   *   }
+   */
+  RCLCPP_PUBLIC
+  void
+  spin_all(std::chrono::nanoseconds max_duration) override;
+
   /// Add a callback group to an executor.
   /**
    * \sa rclcpp::Executor::add_callback_group
@@ -155,113 +192,23 @@ public:
   std::vector<rclcpp::CallbackGroup::WeakPtr>
   get_automatically_added_callback_groups_from_nodes() override;
 
-  /// Spin (blocking) until the future is complete, it times out waiting, or rclcpp is interrupted.
-  /**
-   * \param[in] future The future to wait on. If this function returns SUCCESS, the future can be
-   *   accessed without blocking (though it may still throw an exception).
-   * \param[in] timeout Optional timeout parameter, which gets passed to
-   *    Executor::execute_ready_executables.
-   *   `-1` is block forever, `0` is non-blocking.
-   *   If the time spent inside the blocking loop exceeds this timeout, return a TIMEOUT return
-   *   code.
-   * \return The return code, one of `SUCCESS`, `INTERRUPTED`, or `TIMEOUT`.
-   *
-   *  Example usage:
-   *  rclcpp::executors::StaticSingleThreadedExecutor exec;
-   *  // ... other part of code like creating node
-   *  // define future
-   *  exec.add_node(node);
-   *  exec.spin_until_future_complete(future);
-   */
-  template<typename FutureT, typename TimeRepT = int64_t, typename TimeT = std::milli>
-  rclcpp::FutureReturnCode
-  spin_until_future_complete(
-    FutureT & future,
-    std::chrono::duration<TimeRepT, TimeT> timeout = std::chrono::duration<TimeRepT, TimeT>(-1))
-  {
-    std::future_status status = future.wait_for(std::chrono::seconds(0));
-    if (status == std::future_status::ready) {
-      return rclcpp::FutureReturnCode::SUCCESS;
-    }
-
-    auto end_time = std::chrono::steady_clock::now();
-    std::chrono::nanoseconds timeout_ns = std::chrono::duration_cast<std::chrono::nanoseconds>(
-      timeout);
-    if (timeout_ns > std::chrono::nanoseconds::zero()) {
-      end_time += timeout_ns;
-    }
-    std::chrono::nanoseconds timeout_left = timeout_ns;
-
-    entities_collector_->init(&wait_set_, memory_strategy_, &interrupt_guard_condition_);
-    RCLCPP_SCOPE_EXIT(entities_collector_->fini());
-
-    while (rclcpp::ok(this->context_)) {
-      // Do one set of work.
-      entities_collector_->refresh_wait_set(timeout_left);
-      execute_ready_executables();
-      // Check if the future is set, return SUCCESS if it is.
-      status = future.wait_for(std::chrono::seconds(0));
-      if (status == std::future_status::ready) {
-        return rclcpp::FutureReturnCode::SUCCESS;
-      }
-      // If the original timeout is < 0, then this is blocking, never TIMEOUT.
-      if (timeout_ns < std::chrono::nanoseconds::zero()) {
-        continue;
-      }
-      // Otherwise check if we still have time to wait, return TIMEOUT if not.
-      auto now = std::chrono::steady_clock::now();
-      if (now >= end_time) {
-        return rclcpp::FutureReturnCode::TIMEOUT;
-      }
-      // Subtract the elapsed time from the original timeout.
-      timeout_left = std::chrono::duration_cast<std::chrono::nanoseconds>(end_time - now);
-    }
-
-    // The future did not complete before ok() returned false, return INTERRUPTED.
-    return rclcpp::FutureReturnCode::INTERRUPTED;
-  }
-
-  /// Not yet implemented, see https://github.com/ros2/rclcpp/issues/1219 for tracking
-  RCLCPP_PUBLIC
-  void
-  spin_some(std::chrono::nanoseconds max_duration = std::chrono::nanoseconds(0)) override
-  {
-    (void)max_duration;
-    throw rclcpp::exceptions::UnimplementedError(
-            "spin_some is not implemented for StaticSingleThreadedExecutor, use spin or "
-            "spin_until_future_complete");
-  }
-
-  /// Not yet implemented, see https://github.com/ros2/rclcpp/issues/1219 for tracking
-  RCLCPP_PUBLIC
-  void
-  spin_all(std::chrono::nanoseconds) override
-  {
-    throw rclcpp::exceptions::UnimplementedError(
-            "spin_all is not implemented for StaticSingleThreadedExecutor, use spin or "
-            "spin_until_future_complete");
-  }
-
-  /// Not yet implemented, see https://github.com/ros2/rclcpp/issues/1219 for tracking
-  RCLCPP_PUBLIC
-  void
-  spin_once(std::chrono::nanoseconds timeout = std::chrono::nanoseconds(-1)) override
-  {
-    (void)timeout;
-    throw rclcpp::exceptions::UnimplementedError(
-            "spin_once is not implemented for StaticSingleThreadedExecutor, use spin or "
-            "spin_until_future_complete");
-  }
-
 protected:
-  /// Check which executables in ExecutableList struct are ready from wait_set and execute them.
   /**
-   * \param[in] exec_list Structure that can hold subscriptionbases, timerbases, etc
-   * \param[in] timeout Optional timeout parameter.
+   * @brief Executes ready executables from wait set.
+   * @param spin_once if true executes only the first ready executable.
+   * @return true if any executable was ready.
    */
+  RCLCPP_PUBLIC
+  bool
+  execute_ready_executables(bool spin_once = false);
+
   RCLCPP_PUBLIC
   void
-  execute_ready_executables();
+  spin_some_impl(std::chrono::nanoseconds max_duration, bool exhaustive);
+
+  RCLCPP_PUBLIC
+  void
+  spin_once_impl(std::chrono::nanoseconds timeout) override;
 
 private:
   RCLCPP_DISABLE_COPY(StaticSingleThreadedExecutor)

rclcpp/include/rclcpp/experimental/intra_process_manager.hpp

@@ -207,7 +207,7 @@ public:
       sub_ids.take_shared_subscriptions.size() <= 1)
     {
       // There is at maximum 1 buffer that does not require ownership.
-      // So we this case is equivalent to all the buffers requiring ownership
+      // So this case is equivalent to all the buffers requiring ownership
 
       // Merge the two vector of ids into a unique one
       std::vector<uint64_t> concatenated_vector(sub_ids.take_shared_subscriptions);
@@ -307,7 +307,7 @@ private:
   {
     SubscriptionInfo() = default;
 
-    rclcpp::experimental::SubscriptionIntraProcessBase::SharedPtr subscription;
+    rclcpp::experimental::SubscriptionIntraProcessBase::WeakPtr subscription;
     rmw_qos_profile_t qos;
     const char * topic_name;
     bool use_take_shared_method;
@@ -361,13 +361,16 @@ private:
       if (subscription_it == subscriptions_.end()) {
         throw std::runtime_error("subscription has unexpectedly gone out of scope");
       }
-      auto subscription_base = subscription_it->second.subscription;
+      auto subscription_base = subscription_it->second.subscription.lock();
+      if (subscription_base) {
+        auto subscription = std::static_pointer_cast<
+          rclcpp::experimental::SubscriptionIntraProcess<MessageT>
+          >(subscription_base);
 
-      auto subscription = std::static_pointer_cast<
-        rclcpp::experimental::SubscriptionIntraProcess<MessageT>
-        >(subscription_base);
-
-      subscription->provide_intra_process_message(message);
+        subscription->provide_intra_process_message(message);
+      } else {
+        subscriptions_.erase(id);
+      }
     }
   }
 
@@ -389,24 +392,27 @@ private:
       if (subscription_it == subscriptions_.end()) {
         throw std::runtime_error("subscription has unexpectedly gone out of scope");
       }
-      auto subscription_base = subscription_it->second.subscription;
+      auto subscription_base = subscription_it->second.subscription.lock();
+      if (subscription_base) {
+        auto subscription = std::static_pointer_cast<
+          rclcpp::experimental::SubscriptionIntraProcess<MessageT>
+          >(subscription_base);
 
-      auto subscription = std::static_pointer_cast<
-        rclcpp::experimental::SubscriptionIntraProcess<MessageT>
-        >(subscription_base);
+        if (std::next(it) == subscription_ids.end()) {
+          // If this is the last subscription, give up ownership
+          subscription->provide_intra_process_message(std::move(message));
+        } else {
+          // Copy the message since we have additional subscriptions to serve
+          MessageUniquePtr copy_message;
+          Deleter deleter = message.get_deleter();
+          auto ptr = MessageAllocTraits::allocate(*allocator.get(), 1);
+          MessageAllocTraits::construct(*allocator.get(), ptr, *message);
+          copy_message = MessageUniquePtr(ptr, deleter);
 
-      if (std::next(it) == subscription_ids.end()) {
-        // If this is the last subscription, give up ownership
-        subscription->provide_intra_process_message(std::move(message));
+          subscription->provide_intra_process_message(std::move(copy_message));
+        }
       } else {
-        // Copy the message since we have additional subscriptions to serve
-        MessageUniquePtr copy_message;
-        Deleter deleter = message.get_deleter();
-        auto ptr = MessageAllocTraits::allocate(*allocator.get(), 1);
-        MessageAllocTraits::construct(*allocator.get(), ptr, *message);
-        copy_message = MessageUniquePtr(ptr, deleter);
-
-        subscription->provide_intra_process_message(std::move(copy_message));
+        subscriptions_.erase(subscription_it);
       }
     }
   }

rclcpp/include/rclcpp/experimental/subscription_intra_process.hpp

@@ -18,7 +18,9 @@
 #include <rmw/rmw.h>
 
 #include <functional>
+#include <map>
 #include <memory>
+#include <stdexcept>
 #include <string>
 #include <utility>
 
@@ -115,13 +117,31 @@ public:
   bool
   is_ready(rcl_wait_set_t * wait_set)
   {
-    (void)wait_set;
+    (void) wait_set;
     return buffer_->has_data();
   }
 
-  void execute()
+  std::shared_ptr<void>
+  take_data()
   {
-    execute_impl<CallbackMessageT>();
+    ConstMessageSharedPtr shared_msg;
+    MessageUniquePtr unique_msg;
+
+    if (any_callback_.use_take_shared_method()) {
+      shared_msg = buffer_->consume_shared();
+    } else {
+      unique_msg = buffer_->consume_unique();
+    }
+    return std::static_pointer_cast<void>(
+      std::make_shared<std::pair<ConstMessageSharedPtr, MessageUniquePtr>>(
+        std::pair<ConstMessageSharedPtr, MessageUniquePtr>(
+          shared_msg, std::move(unique_msg)))
+    );
+  }
+
+  void execute(std::shared_ptr<void> & data)
+  {
+    execute_impl<CallbackMessageT>(data);
   }
 
   void
@@ -154,26 +174,35 @@ private:
 
   template<typename T>
   typename std::enable_if<std::is_same<T, rcl_serialized_message_t>::value, void>::type
-  execute_impl()
+  execute_impl(std::shared_ptr<void> & data)
   {
+    (void)data;
     throw std::runtime_error("Subscription intra-process can't handle serialized messages");
   }
 
   template<class T>
   typename std::enable_if<!std::is_same<T, rcl_serialized_message_t>::value, void>::type
-  execute_impl()
+  execute_impl(std::shared_ptr<void> & data)
   {
+    if (!data) {
+      throw std::runtime_error("'data' is empty");
+    }
+
     rmw_message_info_t msg_info;
     msg_info.publisher_gid = {0, {0}};
     msg_info.from_intra_process = true;
 
+    auto shared_ptr = std::static_pointer_cast<std::pair<ConstMessageSharedPtr, MessageUniquePtr>>(
+      data);
+
     if (any_callback_.use_take_shared_method()) {
-      ConstMessageSharedPtr msg = buffer_->consume_shared();
-      any_callback_.dispatch_intra_process(msg, msg_info);
+      ConstMessageSharedPtr shared_msg = shared_ptr->first;
+      any_callback_.dispatch_intra_process(shared_msg, msg_info);
     } else {
-      MessageUniquePtr msg = buffer_->consume_unique();
-      any_callback_.dispatch_intra_process(std::move(msg), msg_info);
+      MessageUniquePtr unique_msg = std::move(shared_ptr->second);
+      any_callback_.dispatch_intra_process(std::move(unique_msg), msg_info);
     }
+    shared_ptr.reset();
   }
 
   AnySubscriptionCallback<CallbackMessageT, Alloc> any_callback_;

rclcpp/include/rclcpp/experimental/subscription_intra_process_base.hpp

@@ -56,8 +56,12 @@ public:
   virtual bool
   is_ready(rcl_wait_set_t * wait_set) = 0;
 
+  virtual
+  std::shared_ptr<void>
+  take_data() = 0;
+
   virtual void
-  execute() = 0;
+  execute(std::shared_ptr<void> & data) = 0;
 
   virtual bool
   use_take_shared_method() const = 0;

rclcpp/include/rclcpp/function_traits.hpp

@@ -162,6 +162,32 @@ struct same_arguments : std::is_same<
 >
 {};
 
+namespace detail
+{
+
+template<typename ReturnTypeT, typename ... Args>
+struct as_std_function_helper;
+
+template<typename ReturnTypeT, typename ... Args>
+struct as_std_function_helper<ReturnTypeT, std::tuple<Args ...>>
+{
+  using type = std::function<ReturnTypeT(Args ...)>;
+};
+
+}  // namespace detail
+
+template<
+  typename FunctorT,
+  typename FunctionTraits = function_traits<FunctorT>
+>
+struct as_std_function
+{
+  using type = typename detail::as_std_function_helper<
+    typename FunctionTraits::return_type,
+    typename FunctionTraits::arguments
+    >::type;
+};
+
 }  // namespace function_traits
 
 }  // namespace rclcpp

rclcpp/include/rclcpp/generic_publisher.hpp

@@ -0,0 +1,127 @@
+// Copyright 2018, Bosch Software Innovations GmbH.
+// Copyright 2021, Apex.AI 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__GENERIC_PUBLISHER_HPP_
+#define RCLCPP__GENERIC_PUBLISHER_HPP_
+
+#include <memory>
+#include <string>
+
+#include "rcpputils/shared_library.hpp"
+
+#include "rclcpp/callback_group.hpp"
+#include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/node_base_interface.hpp"
+#include "rclcpp/node_interfaces/node_topics_interface.hpp"
+#include "rclcpp/publisher_base.hpp"
+#include "rclcpp/qos.hpp"
+#include "rclcpp/serialized_message.hpp"
+#include "rclcpp/typesupport_helpers.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+
+/// %Publisher for serialized messages whose type is not known at compile time.
+/**
+ * Since the type is not known at compile time, this is not a template, and the dynamic library
+ * containing type support information has to be identified and loaded based on the type name.
+ *
+ * It does not support intra-process handling.
+ */
+class GenericPublisher : public rclcpp::PublisherBase
+{
+public:
+  // cppcheck-suppress unknownMacro
+  RCLCPP_SMART_PTR_DEFINITIONS(GenericPublisher)
+
+  /// Constructor.
+  /**
+   * In order to properly publish to a topic, this publisher needs to be added to
+   * the node_topic_interface of the node passed into this constructor.
+   *
+   * \sa rclcpp::Node::create_generic_publisher() or rclcpp::create_generic_publisher() for
+   * creating an instance of this class and adding it to the node_topic_interface.
+   *
+   * \param node_base Pointer to parent node's NodeBaseInterface
+   * \param ts_lib Type support library, needs to correspond to topic_type
+   * \param topic_name Topic name
+   * \param topic_type Topic type
+   * \param qos %QoS settings
+   * \param callback Callback for new messages of serialized form
+   * \param options %Publisher options.
+   * Not all publisher options are currently respected, the only relevant options for this
+   * publisher are `event_callbacks`, `use_default_callbacks`, and `%callback_group`.
+   */
+  template<typename AllocatorT = std::allocator<void>>
+  GenericPublisher(
+    rclcpp::node_interfaces::NodeBaseInterface * node_base,
+    std::shared_ptr<rcpputils::SharedLibrary> ts_lib,
+    const std::string & topic_name,
+    const std::string & topic_type,
+    const rclcpp::QoS & qos,
+    const rclcpp::PublisherOptionsWithAllocator<AllocatorT> & options)
+  : rclcpp::PublisherBase(
+      node_base,
+      topic_name,
+      *rclcpp::get_typesupport_handle(topic_type, "rosidl_typesupport_cpp", *ts_lib),
+      options.template to_rcl_publisher_options<rclcpp::SerializedMessage>(qos)),
+    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;
+
+  /// Publish a rclcpp::SerializedMessage.
+  RCLCPP_PUBLIC
+  void publish(const rclcpp::SerializedMessage & message);
+
+private:
+  // The type support library should stay loaded, so it is stored in the GenericPublisher
+  std::shared_ptr<rcpputils::SharedLibrary> ts_lib_;
+};
+
+}  // namespace rclcpp
+
+#endif  // RCLCPP__GENERIC_PUBLISHER_HPP_

rclcpp/include/rclcpp/generic_subscription.hpp

@@ -0,0 +1,161 @@
+// Copyright 2018, Bosch Software Innovations GmbH.
+// Copyright 2021, Apex.AI 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__GENERIC_SUBSCRIPTION_HPP_
+#define RCLCPP__GENERIC_SUBSCRIPTION_HPP_
+
+#include <functional>
+#include <memory>
+#include <string>
+
+#include "rcpputils/shared_library.hpp"
+
+#include "rclcpp/callback_group.hpp"
+#include "rclcpp/macros.hpp"
+#include "rclcpp/node_interfaces/node_base_interface.hpp"
+#include "rclcpp/node_interfaces/node_topics_interface.hpp"
+#include "rclcpp/qos.hpp"
+#include "rclcpp/serialized_message.hpp"
+#include "rclcpp/subscription_base.hpp"
+#include "rclcpp/typesupport_helpers.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+
+/// %Subscription for serialized messages whose type is not known at compile time.
+/**
+ * Since the type is not known at compile time, this is not a template, and the dynamic library
+ * containing type support information has to be identified and loaded based on the type name.
+ *
+ * It does not support intra-process handling.
+ */
+class GenericSubscription : public rclcpp::SubscriptionBase
+{
+public:
+  // cppcheck-suppress unknownMacro
+  RCLCPP_SMART_PTR_DEFINITIONS(GenericSubscription)
+
+  /// Constructor.
+  /**
+   * In order to properly subscribe to a topic, this subscription needs to be added to
+   * the node_topic_interface of the node passed into this constructor.
+   *
+   * \sa rclcpp::Node::create_generic_subscription() or rclcpp::create_generic_subscription() for
+   * creating an instance of this class and adding it to the node_topic_interface.
+   *
+   * \param node_base Pointer to parent node's NodeBaseInterface
+   * \param ts_lib Type support library, needs to correspond to topic_type
+   * \param topic_name Topic name
+   * \param topic_type Topic type
+   * \param qos %QoS settings
+   * \param callback Callback for new messages of serialized form
+   * \param options %Subscription options.
+   * Not all subscription options are currently respected, the only relevant options for this
+   * subscription are `event_callbacks`, `use_default_callbacks`, `ignore_local_publications`, and
+   * `%callback_group`.
+   */
+  template<typename AllocatorT = std::allocator<void>>
+  GenericSubscription(
+    rclcpp::node_interfaces::NodeBaseInterface * node_base,
+    const std::shared_ptr<rcpputils::SharedLibrary> ts_lib,
+    const std::string & topic_name,
+    const std::string & topic_type,
+    const rclcpp::QoS & qos,
+    // TODO(nnmm): Add variant for callback with message info. See issue #1604.
+    std::function<void(std::shared_ptr<rclcpp::SerializedMessage>)> callback,
+    const rclcpp::SubscriptionOptionsWithAllocator<AllocatorT> & options)
+  : SubscriptionBase(
+      node_base,
+      *rclcpp::get_typesupport_handle(topic_type, "rosidl_typesupport_cpp", *ts_lib),
+      topic_name,
+      options.template to_rcl_subscription_options<rclcpp::SerializedMessage>(qos),
+      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;
+
+  // Same as create_serialized_message() as the subscription is to serialized_messages only
+  RCLCPP_PUBLIC
+  std::shared_ptr<void> create_message() override;
+
+  RCLCPP_PUBLIC
+  std::shared_ptr<rclcpp::SerializedMessage> create_serialized_message() override;
+
+  /// Cast the message to a rclcpp::SerializedMessage and call the callback.
+  RCLCPP_PUBLIC
+  void handle_message(
+    std::shared_ptr<void> & message, const rclcpp::MessageInfo & message_info) override;
+
+  /// This function is currently not implemented.
+  RCLCPP_PUBLIC
+  void handle_loaned_message(
+    void * loaned_message, const rclcpp::MessageInfo & message_info) override;
+
+  // Same as return_serialized_message() as the subscription is to serialized_messages only
+  RCLCPP_PUBLIC
+  void return_message(std::shared_ptr<void> & message) override;
+
+  RCLCPP_PUBLIC
+  void return_serialized_message(std::shared_ptr<rclcpp::SerializedMessage> & message) override;
+
+private:
+  RCLCPP_DISABLE_COPY(GenericSubscription)
+
+  std::function<void(std::shared_ptr<rclcpp::SerializedMessage>)> callback_;
+  // The type support library should stay loaded, so it is stored in the GenericSubscription
+  std::shared_ptr<rcpputils::SharedLibrary> ts_lib_;
+};
+
+}  // namespace rclcpp
+
+#endif  // RCLCPP__GENERIC_SUBSCRIPTION_HPP_

rclcpp/include/rclcpp/graph_listener.hpp

@@ -63,7 +63,7 @@ class GraphListener : public std::enable_shared_from_this<GraphListener>
 {
 public:
   RCLCPP_PUBLIC
-  explicit GraphListener(std::shared_ptr<rclcpp::Context> parent_context);
+  explicit GraphListener(const rclcpp::Context::SharedPtr & parent_context);
 
   RCLCPP_PUBLIC
   virtual ~GraphListener();
@@ -160,14 +160,23 @@ protected:
   void
   run_loop();
 
+  RCLCPP_PUBLIC
+  void
+  init_wait_set();
+
+  RCLCPP_PUBLIC
+  void
+  cleanup_wait_set();
+
 private:
   RCLCPP_DISABLE_COPY(GraphListener)
 
   /** \internal */
   void
-  __shutdown(bool);
+  __shutdown();
 
-  rclcpp::Context::WeakPtr parent_context_;
+  std::weak_ptr<rclcpp::Context> weak_parent_context_;
+  std::shared_ptr<rcl_context_t> rcl_parent_context_;
 
   std::thread listener_thread_;
   bool is_started_;
@@ -179,7 +188,6 @@ private:
   std::vector<rclcpp::node_interfaces::NodeGraphInterface *> node_graph_interfaces_;
 
   rcl_guard_condition_t interrupt_guard_condition_ = rcl_get_zero_initialized_guard_condition();
-  rcl_guard_condition_t * shutdown_guard_condition_;
   rcl_wait_set_t wait_set_ = rcl_get_zero_initialized_wait_set();
 };
 

rclcpp/include/rclcpp/loaned_message.hpp

@@ -183,14 +183,30 @@ public:
   /**
    * A call to `release()` will unmanage the memory for the ROS message.
    * That means that the destructor of this class will not free the memory on scope exit.
+   * If the message is loaned from the middleware but not be published, the user needs to call
+   * `rcl_return_loaned_message_from_publisher` manually.
+   * If the memory is from the local allocator, the memory is freed when the unique pointer
+   * goes out instead.
    *
-   * \return Raw pointer to the message instance.
+   * \return std::unique_ptr to the message instance.
    */
-  MessageT * release()
+  std::unique_ptr<MessageT, std::function<void(MessageT *)>>
+  release()
   {
     auto msg = message_;
     message_ = nullptr;
-    return msg;
+
+    if (pub_.can_loan_messages()) {
+      return std::unique_ptr<MessageT, std::function<void(MessageT *)>>(msg, [](MessageT *) {});
+    }
+
+    return std::unique_ptr<MessageT, std::function<void(MessageT *)>>(
+      msg,
+      [allocator = message_allocator_](MessageT * msg_ptr) mutable {
+        // call destructor before deallocating
+        msg_ptr->~MessageT();
+        allocator.deallocate(msg_ptr, 1);
+      });
   }
 
 protected:

rclcpp/include/rclcpp/logger.hpp

@@ -22,6 +22,7 @@
 
 #include "rcl/node.h"
 #include "rcutils/logging.h"
+#include "rcpputils/filesystem_helper.hpp"
 
 /**
  * \def RCLCPP_LOGGING_ENABLED
@@ -75,6 +76,18 @@ RCLCPP_PUBLIC
 Logger
 get_node_logger(const rcl_node_t * node);
 
+/// Get the current logging directory.
+/**
+ * For more details of how the logging directory is determined,
+ * see \ref rcl_logging_get_logging_directory.
+ *
+ * \returns the logging directory being used.
+ * \throws rclcpp::exceptions::RCLError if an unexpected error occurs.
+ */
+RCLCPP_PUBLIC
+rcpputils::fs::path
+get_logging_directory();
+
 class Logger
 {
 public:

rclcpp/include/rclcpp/message_memory_strategy.hpp

@@ -61,7 +61,7 @@ public:
     message_allocator_ = std::make_shared<MessageAlloc>();
     serialized_message_allocator_ = std::make_shared<SerializedMessageAlloc>();
     buffer_allocator_ = std::make_shared<BufferAlloc>();
-    rcutils_allocator_ = allocator::get_rcl_allocator<char, BufferAlloc>(*buffer_allocator_.get());
+    rcutils_allocator_ = rclcpp::allocator::get_rcl_allocator(*buffer_allocator_.get());
   }
 
   explicit MessageMemoryStrategy(std::shared_ptr<Alloc> allocator)
@@ -69,7 +69,7 @@ public:
     message_allocator_ = std::make_shared<MessageAlloc>(*allocator.get());
     serialized_message_allocator_ = std::make_shared<SerializedMessageAlloc>(*allocator.get());
     buffer_allocator_ = std::make_shared<BufferAlloc>(*allocator.get());
-    rcutils_allocator_ = allocator::get_rcl_allocator<char, BufferAlloc>(*buffer_allocator_.get());
+    rcutils_allocator_ = rclcpp::allocator::get_rcl_allocator(*buffer_allocator_.get());
   }
 
   virtual ~MessageMemoryStrategy() = default;

rclcpp/include/rclcpp/network_flow_endpoint.hpp

@@ -0,0 +1,115 @@
+// Copyright 2020 Ericsson AB
+//
+// 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__NETWORK_FLOW_ENDPOINT_HPP_
+#define RCLCPP__NETWORK_FLOW_ENDPOINT_HPP_
+
+#include <cstdint>
+#include <string>
+#include <iostream>
+
+#include "rcl/network_flow_endpoints.h"
+
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+
+/// Forward declaration
+class NetworkFlowEndpoint;
+
+/// Check if two NetworkFlowEndpoint instances are equal
+RCLCPP_PUBLIC
+bool operator==(const NetworkFlowEndpoint & left, const NetworkFlowEndpoint & right);
+
+/// Check if two NetworkFlowEndpoint instances are not equal
+RCLCPP_PUBLIC
+bool operator!=(const NetworkFlowEndpoint & left, const NetworkFlowEndpoint & right);
+
+/// Streaming helper for NetworkFlowEndpoint
+RCLCPP_PUBLIC
+std::ostream & operator<<(std::ostream & os, const NetworkFlowEndpoint & network_flow_endpoint);
+
+/**
+ * Class describes a network flow endpoint based on the counterpart definition
+ * in the RMW layer.
+ */
+class NetworkFlowEndpoint
+{
+public:
+  /// Construct from rcl_network_flow_endpoint_t
+  RCLCPP_PUBLIC
+  explicit NetworkFlowEndpoint(const rcl_network_flow_endpoint_t & network_flow_endpoint)
+  : transport_protocol_(
+      rcl_network_flow_endpoint_get_transport_protocol_string(network_flow_endpoint.
+      transport_protocol)),
+    internet_protocol_(
+      rcl_network_flow_endpoint_get_internet_protocol_string(
+        network_flow_endpoint.internet_protocol)),
+    transport_port_(network_flow_endpoint.transport_port),
+    flow_label_(network_flow_endpoint.flow_label),
+    dscp_(network_flow_endpoint.dscp),
+    internet_address_(network_flow_endpoint.internet_address)
+  {
+  }
+
+  /// Get transport protocol
+  RCLCPP_PUBLIC
+  const std::string & transport_protocol() const;
+
+  /// Get internet protocol
+  RCLCPP_PUBLIC
+  const std::string & internet_protocol() const;
+
+  /// Get transport port
+  RCLCPP_PUBLIC
+  uint16_t transport_port() const;
+
+  /// Get flow label
+  RCLCPP_PUBLIC
+  uint32_t flow_label() const;
+
+  /// Get DSCP
+  RCLCPP_PUBLIC
+  uint8_t dscp() const;
+
+  /// Get internet address
+  RCLCPP_PUBLIC
+  const std::string & internet_address() const;
+
+  /// Compare two NetworkFlowEndpoint instances
+  friend bool rclcpp::operator==(
+    const NetworkFlowEndpoint & left,
+    const NetworkFlowEndpoint & right);
+  friend bool rclcpp::operator!=(
+    const NetworkFlowEndpoint & left,
+    const NetworkFlowEndpoint & right);
+
+  /// Streaming helper
+  friend std::ostream & rclcpp::operator<<(
+    std::ostream & os,
+    const NetworkFlowEndpoint & network_flow_endpoint);
+
+private:
+  std::string transport_protocol_;
+  std::string internet_protocol_;
+  uint16_t transport_port_;
+  uint32_t flow_label_;
+  uint8_t dscp_;
+  std::string internet_address_;
+};
+
+}  // namespace rclcpp
+
+#endif  // RCLCPP__NETWORK_FLOW_ENDPOINT_HPP_

rclcpp/include/rclcpp/node.hpp

@@ -17,6 +17,7 @@
 
 #include <atomic>
 #include <condition_variable>
+#include <functional>
 #include <list>
 #include <map>
 #include <memory>
@@ -41,6 +42,8 @@
 #include "rclcpp/clock.hpp"
 #include "rclcpp/context.hpp"
 #include "rclcpp/event.hpp"
+#include "rclcpp/generic_publisher.hpp"
+#include "rclcpp/generic_subscription.hpp"
 #include "rclcpp/logger.hpp"
 #include "rclcpp/macros.hpp"
 #include "rclcpp/message_memory_strategy.hpp"
@@ -163,7 +166,7 @@ public:
    * pub = node->create_publisher<MsgT>("chatter", QoS(10));  // implicitly KeepLast
    * pub = node->create_publisher<MsgT>("chatter", QoS(KeepLast(10)));
    * pub = node->create_publisher<MsgT>("chatter", QoS(KeepAll()));
-   * pub = node->create_publisher<MsgT>("chatter", QoS(1).best_effort().volatile());
+   * pub = node->create_publisher<MsgT>("chatter", QoS(1).best_effort().durability_volatile());
    * {
    *   rclcpp::QoS custom_qos(KeepLast(10), rmw_qos_profile_sensor_data);
    *   pub = node->create_publisher<MsgT>("chatter", custom_qos);
@@ -266,6 +269,55 @@ public:
     const rmw_qos_profile_t & qos_profile = rmw_qos_profile_services_default,
     rclcpp::CallbackGroup::SharedPtr group = nullptr);
 
+  /// Create and return a GenericPublisher.
+  /**
+   * The returned pointer will never be empty, but this function can throw various exceptions, for
+   * instance when the message's package can not be found on the AMENT_PREFIX_PATH.
+   *
+   * \param[in] topic_name Topic name
+   * \param[in] topic_type Topic type
+   * \param[in] qos %QoS settings
+   * \param options %Publisher options.
+   * Not all publisher options are currently respected, the only relevant options for this
+   * publisher are `event_callbacks`, `use_default_callbacks`, and `%callback_group`.
+   * \return Shared pointer to the created generic publisher.
+   */
+  template<typename AllocatorT = std::allocator<void>>
+  std::shared_ptr<rclcpp::GenericPublisher> create_generic_publisher(
+    const std::string & topic_name,
+    const std::string & topic_type,
+    const rclcpp::QoS & qos,
+    const rclcpp::PublisherOptionsWithAllocator<AllocatorT> & options = (
+      rclcpp::PublisherOptionsWithAllocator<AllocatorT>()
+    )
+  );
+
+  /// Create and return a GenericSubscription.
+  /**
+   * The returned pointer will never be empty, but this function can throw various exceptions, for
+   * instance when the message's package can not be found on the AMENT_PREFIX_PATH.
+   *
+   * \param[in] topic_name Topic name
+   * \param[in] topic_type Topic type
+   * \param[in] qos %QoS settings
+   * \param[in] callback Callback for new messages of serialized form
+   * \param[in] options %Subscription options.
+   * Not all subscription options are currently respected, the only relevant options for this
+ * subscription are `event_callbacks`, `use_default_callbacks`, `ignore_local_publications`, and
+ * `%callback_group`.
+   * \return Shared pointer to the created generic subscription.
+   */
+  template<typename AllocatorT = std::allocator<void>>
+  std::shared_ptr<rclcpp::GenericSubscription> create_generic_subscription(
+    const std::string & topic_name,
+    const std::string & topic_type,
+    const rclcpp::QoS & qos,
+    std::function<void(std::shared_ptr<rclcpp::SerializedMessage>)> callback,
+    const rclcpp::SubscriptionOptionsWithAllocator<AllocatorT> & options = (
+      rclcpp::SubscriptionOptionsWithAllocator<AllocatorT>()
+    )
+  );
+
   /// Declare and initialize a parameter, return the effective value.
   /**
    * This method is used to declare that a parameter exists on this node.
@@ -305,16 +357,59 @@ public:
    *   name is invalid.
    * \throws rclcpp::exceptions::InvalidParameterValueException if initial
    *   value fails to be set.
+   * \throws rclcpp::exceptions::InvalidParameterTypeException
+   *   if the type of the default value or override is wrong.
    */
   RCLCPP_PUBLIC
   const rclcpp::ParameterValue &
   declare_parameter(
     const std::string & name,
-    const rclcpp::ParameterValue & default_value = rclcpp::ParameterValue(),
+    const rclcpp::ParameterValue & default_value,
     const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor =
     rcl_interfaces::msg::ParameterDescriptor(),
     bool ignore_override = false);
 
+  /// Declare and initialize a parameter, return the effective value.
+  /**
+   * Same as the previous one, but a default value is not provided and the user
+   * must provide a parameter override of the correct type.
+   *
+   * \param[in] name The name of the parameter.
+   * \param[in] type Desired type of the parameter, which will enforced at runtime.
+   * \param[in] parameter_descriptor An optional, custom description for
+   *   the parameter.
+   * \param[in] ignore_override When `true`, the parameter override is ignored.
+   *    Default to `false`.
+   * \return A const reference to the value of the parameter.
+   * \throws Same as the previous overload taking a default value.
+   * \throws rclcpp::exceptions::InvalidParameterTypeException
+   *   if an override is not provided or the provided override is of the wrong type.
+   */
+  RCLCPP_PUBLIC
+  const rclcpp::ParameterValue &
+  declare_parameter(
+    const std::string & name,
+    rclcpp::ParameterType type,
+    const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor =
+    rcl_interfaces::msg::ParameterDescriptor{},
+    bool ignore_override = false);
+
+  /// Declare a parameter
+  [[deprecated(
+    "declare_parameter() with only a name is deprecated and will be deleted in the future.\n" \
+    "If you want to declare a parameter that won't change type without a default value use:\n" \
+    "`node->declare_parameter<ParameterT>(name)`, where e.g. ParameterT=int64_t.\n\n" \
+    "If you want to declare a parameter that can dynamically change type use:\n" \
+    "```\n" \
+    "rcl_interfaces::msg::ParameterDescriptor descriptor;\n" \
+    "descriptor.dynamic_typing = true;\n" \
+    "node->declare_parameter(name, rclcpp::ParameterValue{}, descriptor);\n" \
+    "```"
+  )]]
+  RCLCPP_PUBLIC
+  const rclcpp::ParameterValue &
+  declare_parameter(const std::string & name);
+
   /// Declare and initialize a parameter with a type.
   /**
    * See the non-templated declare_parameter() on this class for details.
@@ -345,6 +440,18 @@ public:
     rcl_interfaces::msg::ParameterDescriptor(),
     bool ignore_override = false);
 
+  /// Declare and initialize a parameter with a type.
+  /**
+   * See the non-templated declare_parameter() on this class for details.
+   */
+  template<typename ParameterT>
+  auto
+  declare_parameter(
+    const std::string & name,
+    const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor =
+    rcl_interfaces::msg::ParameterDescriptor(),
+    bool ignore_override = false);
+
   /// Declare and initialize several parameters with the same namespace and type.
   /**
    * For each key in the map, a parameter with a name of "namespace.key"
@@ -785,6 +892,9 @@ public:
    *
    * This allows the node developer to control which parameters may be changed.
    *
+   * It is considered bad practice to reject changes for "unknown" parameters as this prevents
+   * other parts of the node (that may be aware of these parameters) from handling them.
+   *
    * Note that the callback is called when declare_parameter() and its variants
    * are called, and so you cannot assume the parameter has been set before
    * this callback, so when checking a new value against the existing one, you

rclcpp/include/rclcpp/node_impl.hpp

@@ -36,10 +36,12 @@
 
 #include "rclcpp/contexts/default_context.hpp"
 #include "rclcpp/create_client.hpp"
+#include "rclcpp/create_generic_publisher.hpp"
+#include "rclcpp/create_generic_subscription.hpp"
 #include "rclcpp/create_publisher.hpp"
 #include "rclcpp/create_service.hpp"
-#include "rclcpp/create_timer.hpp"
 #include "rclcpp/create_subscription.hpp"
+#include "rclcpp/create_timer.hpp"
 #include "rclcpp/detail/resolve_enable_topic_statistics.hpp"
 #include "rclcpp/parameter.hpp"
 #include "rclcpp/qos.hpp"
@@ -152,6 +154,43 @@ Node::create_service(
     group);
 }
 
+template<typename AllocatorT>
+std::shared_ptr<rclcpp::GenericPublisher>
+Node::create_generic_publisher(
+  const std::string & topic_name,
+  const std::string & topic_type,
+  const rclcpp::QoS & qos,
+  const rclcpp::PublisherOptionsWithAllocator<AllocatorT> & options)
+{
+  return rclcpp::create_generic_publisher(
+    node_topics_,
+    extend_name_with_sub_namespace(topic_name, this->get_sub_namespace()),
+    topic_type,
+    qos,
+    options
+  );
+}
+
+template<typename AllocatorT>
+std::shared_ptr<rclcpp::GenericSubscription>
+Node::create_generic_subscription(
+  const std::string & topic_name,
+  const std::string & topic_type,
+  const rclcpp::QoS & qos,
+  std::function<void(std::shared_ptr<rclcpp::SerializedMessage>)> callback,
+  const rclcpp::SubscriptionOptionsWithAllocator<AllocatorT> & options)
+{
+  return rclcpp::create_generic_subscription(
+    node_topics_,
+    extend_name_with_sub_namespace(topic_name, this->get_sub_namespace()),
+    topic_type,
+    qos,
+    std::move(callback),
+    options
+  );
+}
+
+
 template<typename ParameterT>
 auto
 Node::declare_parameter(
@@ -172,6 +211,24 @@ Node::declare_parameter(
   }
 }
 
+template<typename ParameterT>
+auto
+Node::declare_parameter(
+  const std::string & name,
+  const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor,
+  bool ignore_override)
+{
+  // get advantage of parameter value template magic to get
+  // the correct rclcpp::ParameterType from ParameterT
+  rclcpp::ParameterValue value{ParameterT{}};
+  return this->declare_parameter(
+    name,
+    value.get_type(),
+    parameter_descriptor,
+    ignore_override
+  ).get<ParameterT>();
+}
+
 template<typename ParameterT>
 std::vector<ParameterT>
 Node::declare_parameters(

rclcpp/include/rclcpp/node_interfaces/node_base.hpp

@@ -118,6 +118,10 @@ public:
   bool
   get_enable_topic_statistics_default() const override;
 
+  std::string
+  resolve_topic_or_service_name(
+    const std::string & name, bool is_service, bool only_expand = false) const override;
+
 private:
   RCLCPP_DISABLE_COPY(NodeBase)
 

rclcpp/include/rclcpp/node_interfaces/node_base_interface.hpp

@@ -163,6 +163,13 @@ public:
   virtual
   bool
   get_enable_topic_statistics_default() const = 0;
+
+  /// Expand and remap a given topic or service name.
+  RCLCPP_PUBLIC
+  virtual
+  std::string
+  resolve_topic_or_service_name(
+    const std::string & name, bool is_service, bool only_expand = false) const = 0;
 };
 
 }  // namespace node_interfaces

rclcpp/include/rclcpp/node_interfaces/node_parameters.hpp

@@ -103,13 +103,42 @@ public:
   virtual
   ~NodeParameters();
 
+// This is overriding a deprecated method, so we need to ignore the deprecation warning here.
+// Users of the method will still get a warning!
+#ifndef _WIN32
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#else
+# pragma warning(push)
+# pragma warning(disable: 4996)
+#endif
+  [[deprecated(RCLCPP_INTERNAL_NODE_PARAMETERS_INTERFACE_DEPRECATE_DECLARE)]]
+  RCLCPP_PUBLIC
+  const rclcpp::ParameterValue &
+  declare_parameter(const std::string & name) override;
+#ifndef _WIN32
+# pragma GCC diagnostic pop
+#else
+# pragma warning(pop)
+#endif
+
   RCLCPP_PUBLIC
   const rclcpp::ParameterValue &
   declare_parameter(
     const std::string & name,
     const rclcpp::ParameterValue & default_value,
-    const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor,
-    bool ignore_override) override;
+    const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor =
+    rcl_interfaces::msg::ParameterDescriptor{},
+    bool ignore_override = false) override;
+
+  RCLCPP_PUBLIC
+  const rclcpp::ParameterValue &
+  declare_parameter(
+    const std::string & name,
+    rclcpp::ParameterType type,
+    const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor =
+    rcl_interfaces::msg::ParameterDescriptor(),
+    bool ignore_override = false) override;
 
   RCLCPP_PUBLIC
   void

rclcpp/include/rclcpp/node_interfaces/node_parameters_interface.hpp

@@ -45,6 +45,17 @@ struct OnSetParametersCallbackHandle
   OnParametersSetCallbackType callback;
 };
 
+#define RCLCPP_INTERNAL_NODE_PARAMETERS_INTERFACE_DEPRECATE_DECLARE \
+  "declare_parameter() with only a name is deprecated and will be deleted in the future.\n" \
+  "If you want to declare a parameter that won't change type without a default value use:\n" \
+  "`node_params->declare_parameter(name, type)`, with e.g. type=rclcpp::PARAMETER_INTEGER.\n\n" \
+  "If you want to declare a parameter that can dynamically change type use:\n" \
+  "```\n" \
+  "rcl_interfaces::msg::ParameterDescriptor descriptor;\n" \
+  "descriptor.dynamic_typing = true;\n" \
+  "node_params->declare_parameter(name, rclcpp::ParameterValue{}, descriptor);\n" \
+  "```"
+
 /// Pure virtual interface class for the NodeParameters part of the Node API.
 class NodeParametersInterface
 {
@@ -55,6 +66,15 @@ public:
   virtual
   ~NodeParametersInterface() = default;
 
+  /// Declare a parameter.
+  /**
+   * \sa rclcpp::Node::declare_parameter
+   */
+  [[deprecated(RCLCPP_INTERNAL_NODE_PARAMETERS_INTERFACE_DEPRECATE_DECLARE)]]
+  virtual
+  const rclcpp::ParameterValue &
+  declare_parameter(const std::string & name) = 0;
+
   /// Declare and initialize a parameter.
   /**
    * \sa rclcpp::Node::declare_parameter
@@ -64,7 +84,21 @@ public:
   const rclcpp::ParameterValue &
   declare_parameter(
     const std::string & name,
-    const rclcpp::ParameterValue & default_value = rclcpp::ParameterValue(),
+    const rclcpp::ParameterValue & default_value,
+    const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor =
+    rcl_interfaces::msg::ParameterDescriptor(),
+    bool ignore_override = false) = 0;
+
+  /// Declare a parameter.
+  /**
+   * \sa rclcpp::Node::declare_parameter
+   */
+  RCLCPP_PUBLIC
+  virtual
+  const rclcpp::ParameterValue &
+  declare_parameter(
+    const std::string & name,
+    rclcpp::ParameterType type,
     const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor =
     rcl_interfaces::msg::ParameterDescriptor(),
     bool ignore_override = false) = 0;
@@ -96,7 +130,7 @@ public:
   std::vector<rcl_interfaces::msg::SetParametersResult>
   set_parameters(const std::vector<rclcpp::Parameter> & parameters) = 0;
 
-  /// Set and initialize a parameter, all at once.
+  /// Set one or more parameters, all at once.
   /**
    * \sa rclcpp::Node::set_parameters_atomically
    */

rclcpp/include/rclcpp/node_interfaces/node_services.hpp

@@ -15,6 +15,8 @@
 #ifndef RCLCPP__NODE_INTERFACES__NODE_SERVICES_HPP_
 #define RCLCPP__NODE_INTERFACES__NODE_SERVICES_HPP_
 
+#include <string>
+
 #include "rclcpp/callback_group.hpp"
 #include "rclcpp/client.hpp"
 #include "rclcpp/macros.hpp"
@@ -53,6 +55,10 @@ public:
     rclcpp::ServiceBase::SharedPtr service_base_ptr,
     rclcpp::CallbackGroup::SharedPtr group) override;
 
+  RCLCPP_PUBLIC
+  std::string
+  resolve_service_name(const std::string & name, bool only_expand = false) const override;
+
 private:
   RCLCPP_DISABLE_COPY(NodeServices)
 

rclcpp/include/rclcpp/node_interfaces/node_services_interface.hpp

@@ -15,6 +15,8 @@
 #ifndef RCLCPP__NODE_INTERFACES__NODE_SERVICES_INTERFACE_HPP_
 #define RCLCPP__NODE_INTERFACES__NODE_SERVICES_INTERFACE_HPP_
 
+#include <string>
+
 #include "rclcpp/callback_group.hpp"
 #include "rclcpp/client.hpp"
 #include "rclcpp/macros.hpp"
@@ -49,6 +51,12 @@ public:
   add_service(
     rclcpp::ServiceBase::SharedPtr service_base_ptr,
     rclcpp::CallbackGroup::SharedPtr group) = 0;
+
+  /// Get the remapped and expanded service name given a input name.
+  RCLCPP_PUBLIC
+  virtual
+  std::string
+  resolve_service_name(const std::string & name, bool only_expand = false) const = 0;
 };
 
 }  // namespace node_interfaces

rclcpp/include/rclcpp/node_interfaces/node_time_source.hpp

@@ -48,7 +48,8 @@ public:
     rclcpp::node_interfaces::NodeLoggingInterface::SharedPtr node_logging,
     rclcpp::node_interfaces::NodeClockInterface::SharedPtr node_clock,
     rclcpp::node_interfaces::NodeParametersInterface::SharedPtr node_parameters,
-    const rclcpp::QoS & qos = rclcpp::RosoutQoS()
+    const rclcpp::QoS & qos = rclcpp::RosoutQoS(),
+    bool use_clock_thread = true
   );
 
   RCLCPP_PUBLIC

rclcpp/include/rclcpp/node_interfaces/node_topics.hpp

@@ -81,6 +81,10 @@ public:
   rclcpp::node_interfaces::NodeTimersInterface *
   get_node_timers_interface() const override;
 
+  RCLCPP_PUBLIC
+  std::string
+  resolve_topic_name(const std::string & name, bool only_expand = false) const override;
+
 private:
   RCLCPP_DISABLE_COPY(NodeTopics)
 

rclcpp/include/rclcpp/node_interfaces/node_topics_interface.hpp

@@ -86,6 +86,12 @@ public:
   virtual
   rclcpp::node_interfaces::NodeTimersInterface *
   get_node_timers_interface() const = 0;
+
+  /// Get a remapped and expanded topic name given an input name.
+  RCLCPP_PUBLIC
+  virtual
+  std::string
+  resolve_topic_name(const std::string & name, bool only_expand = false) const = 0;
 };
 
 }  // namespace node_interfaces

rclcpp/include/rclcpp/node_options.hpp

@@ -47,6 +47,7 @@ public:
    *   - start_parameter_services = true
    *   - start_parameter_event_publisher = true
    *   - clock_qos = rclcpp::ClockQoS()
+   *   - use_clock_thread = true
    *   - rosout_qos = rclcpp::RosoutQoS()
    *   - parameter_event_qos = rclcpp::ParameterEventQoS
    *     - with history setting and depth from rmw_qos_profile_parameter_events
@@ -258,6 +259,20 @@ public:
   NodeOptions &
   clock_qos(const rclcpp::QoS & clock_qos);
 
+
+  /// Return the use_clock_thread flag.
+  RCLCPP_PUBLIC
+  bool
+  use_clock_thread() const;
+
+  /// Set the use_clock_thread flag, return this for parameter idiom.
+  /**
+   * If true, a dedicated thread will be used to subscribe to "/clock" topic.
+   */
+  RCLCPP_PUBLIC
+  NodeOptions &
+  use_clock_thread(bool use_clock_thread);
+
   /// Return a reference to the parameter_event_qos QoS.
   RCLCPP_PUBLIC
   const rclcpp::QoS &
@@ -384,6 +399,8 @@ private:
 
   rclcpp::QoS clock_qos_ = rclcpp::ClockQoS();
 
+  bool use_clock_thread_ {true};
+
   rclcpp::QoS parameter_event_qos_ = rclcpp::ParameterEventsQoS(
     rclcpp::QoSInitialization::from_rmw(rmw_qos_profile_parameter_events)
   );

rclcpp/include/rclcpp/parameter_client.hpp

@@ -15,6 +15,8 @@
 #ifndef RCLCPP__PARAMETER_CLIENT_HPP_
 #define RCLCPP__PARAMETER_CLIENT_HPP_
 
+#include <functional>
+#include <future>
 #include <memory>
 #include <string>
 #include <utility>
@@ -29,11 +31,14 @@
 #include "rcl_interfaces/srv/list_parameters.hpp"
 #include "rcl_interfaces/srv/set_parameters.hpp"
 #include "rcl_interfaces/srv/set_parameters_atomically.hpp"
+#include "rcl_yaml_param_parser/parser.h"
+#include "rclcpp/exceptions.hpp"
 #include "rclcpp/executors.hpp"
 #include "rclcpp/create_subscription.hpp"
 #include "rclcpp/macros.hpp"
 #include "rclcpp/node.hpp"
 #include "rclcpp/parameter.hpp"
+#include "rclcpp/parameter_map.hpp"
 #include "rclcpp/type_support_decl.hpp"
 #include "rclcpp/visibility_control.hpp"
 #include "rmw/rmw.h"
@@ -120,6 +125,14 @@ public:
       void(std::shared_future<std::vector<rclcpp::Parameter>>)
     > callback = nullptr);
 
+  RCLCPP_PUBLIC
+  std::shared_future<std::vector<rcl_interfaces::msg::ParameterDescriptor>>
+  describe_parameters(
+    const std::vector<std::string> & names,
+    std::function<
+      void(std::shared_future<std::vector<rcl_interfaces::msg::ParameterDescriptor>>)
+    > callback = nullptr);
+
   RCLCPP_PUBLIC
   std::shared_future<std::vector<rclcpp::ParameterType>>
   get_parameter_types(
@@ -144,6 +157,42 @@ public:
       void(std::shared_future<rcl_interfaces::msg::SetParametersResult>)
     > callback = nullptr);
 
+  /// Delete several parameters at once.
+  /**
+   * This function behaves like command-line tool `ros2 param delete` would.
+   *
+   * \param parameters_names vector of parameters names
+   * \return the future of the set_parameter service used to delete the parameters
+   */
+  RCLCPP_PUBLIC
+  std::shared_future<std::vector<rcl_interfaces::msg::SetParametersResult>>
+  delete_parameters(
+    const std::vector<std::string> & parameters_names);
+
+  /// Load parameters from yaml file.
+  /**
+   * This function behaves like command-line tool `ros2 param load` would.
+   *
+   * \param yaml_filename the full name of the yaml file
+   * \return the future of the set_parameter service used to load the parameters
+   */
+  RCLCPP_PUBLIC
+  std::shared_future<std::vector<rcl_interfaces::msg::SetParametersResult>>
+  load_parameters(
+    const std::string & yaml_filename);
+
+  /// Load parameters from parameter map.
+  /**
+   * This function filters the parameters to be set based on the node name.
+   *
+   * \param yaml_filename the full name of the yaml file
+   * \return the future of the set_parameter service used to load the parameters
+   * \throw InvalidParametersException if there is no parameter to set
+   */
+  RCLCPP_PUBLIC
+  std::shared_future<std::vector<rcl_interfaces::msg::SetParametersResult>>
+  load_parameters(const rclcpp::ParameterMap & parameter_map);
+
   RCLCPP_PUBLIC
   std::shared_future<rcl_interfaces::msg::ListParametersResult>
   list_parameters(
@@ -332,9 +381,17 @@ public:
       qos_profile);
   }
 
-  RCLCPP_PUBLIC
+  template<typename RepT = int64_t, typename RatioT = std::milli>
   std::vector<rclcpp::Parameter>
-  get_parameters(const std::vector<std::string> & parameter_names);
+  get_parameters(
+    const std::vector<std::string> & parameter_names,
+    std::chrono::duration<RepT, RatioT> timeout = std::chrono::duration<RepT, RatioT>(-1))
+  {
+    return get_parameters(
+      parameter_names,
+      std::chrono::duration_cast<std::chrono::nanoseconds>(timeout)
+    );
+  }
 
   RCLCPP_PUBLIC
   bool
@@ -378,23 +435,107 @@ public:
     );
   }
 
-  RCLCPP_PUBLIC
+  template<typename RepT = int64_t, typename RatioT = std::milli>
+  std::vector<rcl_interfaces::msg::ParameterDescriptor>
+  describe_parameters(
+    const std::vector<std::string> & parameter_names,
+    std::chrono::duration<RepT, RatioT> timeout = std::chrono::duration<RepT, RatioT>(-1))
+  {
+    return describe_parameters(
+      parameter_names,
+      std::chrono::duration_cast<std::chrono::nanoseconds>(timeout)
+    );
+  }
+
+  template<typename RepT = int64_t, typename RatioT = std::milli>
   std::vector<rclcpp::ParameterType>
-  get_parameter_types(const std::vector<std::string> & parameter_names);
+  get_parameter_types(
+    const std::vector<std::string> & parameter_names,
+    std::chrono::duration<RepT, RatioT> timeout = std::chrono::duration<RepT, RatioT>(-1))
+  {
+    return get_parameter_types(
+      parameter_names,
+      std::chrono::duration_cast<std::chrono::nanoseconds>(timeout)
+    );
+  }
 
-  RCLCPP_PUBLIC
+  template<typename RepT = int64_t, typename RatioT = std::milli>
   std::vector<rcl_interfaces::msg::SetParametersResult>
-  set_parameters(const std::vector<rclcpp::Parameter> & parameters);
+  set_parameters(
+    const std::vector<rclcpp::Parameter> & parameters,
+    std::chrono::duration<RepT, RatioT> timeout = std::chrono::duration<RepT, RatioT>(-1))
+  {
+    return set_parameters(
+      parameters,
+      std::chrono::duration_cast<std::chrono::nanoseconds>(timeout)
+    );
+  }
 
-  RCLCPP_PUBLIC
+  template<typename RepT = int64_t, typename RatioT = std::milli>
   rcl_interfaces::msg::SetParametersResult
-  set_parameters_atomically(const std::vector<rclcpp::Parameter> & parameters);
+  set_parameters_atomically(
+    const std::vector<rclcpp::Parameter> & parameters,
+    std::chrono::duration<RepT, RatioT> timeout = std::chrono::duration<RepT, RatioT>(-1))
+  {
+    return set_parameters_atomically(
+      parameters,
+      std::chrono::duration_cast<std::chrono::nanoseconds>(timeout)
+    );
+  }
 
-  RCLCPP_PUBLIC
+  /// Delete several parameters at once.
+  /**
+   * This function behaves like command-line tool `ros2 param delete` would.
+   *
+   * \param parameters_names vector of parameters names
+   * \param timeout for the spin used to make it synchronous
+   * \return the future of the set_parameter service used to delete the parameters
+   */
+  template<typename RepT = int64_t, typename RatioT = std::milli>
+  std::vector<rcl_interfaces::msg::SetParametersResult>
+  delete_parameters(
+    const std::vector<std::string> & parameters_names,
+    std::chrono::duration<RepT, RatioT> timeout = std::chrono::duration<RepT, RatioT>(-1))
+  {
+    return delete_parameters(
+      parameters_names,
+      std::chrono::duration_cast<std::chrono::nanoseconds>(timeout)
+    );
+  }
+
+  /// Load parameters from yaml file.
+  /**
+   * This function behaves like command-line tool `ros2 param load` would.
+   *
+   * \param yaml_filename the full name of the yaml file
+   * \param timeout for the spin used to make it synchronous
+   * \return the future of the set_parameter service used to load the parameters
+   */
+  template<typename RepT = int64_t, typename RatioT = std::milli>
+  std::vector<rcl_interfaces::msg::SetParametersResult>
+  load_parameters(
+    const std::string & yaml_filename,
+    std::chrono::duration<RepT, RatioT> timeout = std::chrono::duration<RepT, RatioT>(-1))
+  {
+    return load_parameters(
+      yaml_filename,
+      std::chrono::duration_cast<std::chrono::nanoseconds>(timeout)
+    );
+  }
+
+  template<typename RepT = int64_t, typename RatioT = std::milli>
   rcl_interfaces::msg::ListParametersResult
   list_parameters(
     const std::vector<std::string> & parameter_prefixes,
-    uint64_t depth);
+    uint64_t depth,
+    std::chrono::duration<RepT, RatioT> timeout = std::chrono::duration<RepT, RatioT>(-1))
+  {
+    return list_parameters(
+      parameter_prefixes,
+      depth,
+      std::chrono::duration_cast<std::chrono::nanoseconds>(timeout)
+    );
+  }
 
   template<typename CallbackT>
   typename rclcpp::Subscription<rcl_interfaces::msg::ParameterEvent>::SharedPtr
@@ -437,6 +578,56 @@ public:
     return async_parameters_client_->wait_for_service(timeout);
   }
 
+protected:
+  RCLCPP_PUBLIC
+  std::vector<rclcpp::Parameter>
+  get_parameters(
+    const std::vector<std::string> & parameter_names,
+    std::chrono::nanoseconds timeout);
+
+  RCLCPP_PUBLIC
+  std::vector<rcl_interfaces::msg::ParameterDescriptor>
+  describe_parameters(
+    const std::vector<std::string> & parameter_names,
+    std::chrono::nanoseconds timeout);
+
+  RCLCPP_PUBLIC
+  std::vector<rclcpp::ParameterType>
+  get_parameter_types(
+    const std::vector<std::string> & parameter_names,
+    std::chrono::nanoseconds timeout);
+
+  RCLCPP_PUBLIC
+  std::vector<rcl_interfaces::msg::SetParametersResult>
+  set_parameters(
+    const std::vector<rclcpp::Parameter> & parameters,
+    std::chrono::nanoseconds timeout);
+
+  RCLCPP_PUBLIC
+  std::vector<rcl_interfaces::msg::SetParametersResult>
+  delete_parameters(
+    const std::vector<std::string> & parameters_names,
+    std::chrono::nanoseconds timeout);
+
+  RCLCPP_PUBLIC
+  std::vector<rcl_interfaces::msg::SetParametersResult>
+  load_parameters(
+    const std::string & yaml_filename,
+    std::chrono::nanoseconds timeout);
+
+  RCLCPP_PUBLIC
+  rcl_interfaces::msg::SetParametersResult
+  set_parameters_atomically(
+    const std::vector<rclcpp::Parameter> & parameters,
+    std::chrono::nanoseconds timeout);
+
+  RCLCPP_PUBLIC
+  rcl_interfaces::msg::ListParametersResult
+  list_parameters(
+    const std::vector<std::string> & parameter_prefixes,
+    uint64_t depth,
+    std::chrono::nanoseconds timeout);
+
 private:
   rclcpp::Executor::SharedPtr executor_;
   const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_base_interface_;

rclcpp/include/rclcpp/parameter_event_handler.hpp

@@ -0,0 +1,338 @@
+// Copyright 2019 Intel Corporation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__PARAMETER_EVENT_HANDLER_HPP_
+#define RCLCPP__PARAMETER_EVENT_HANDLER_HPP_
+
+#include <list>
+#include <memory>
+#include <string>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+#include "rclcpp/create_subscription.hpp"
+#include "rclcpp/node_interfaces/get_node_base_interface.hpp"
+#include "rclcpp/node_interfaces/get_node_topics_interface.hpp"
+#include "rclcpp/node_interfaces/node_base_interface.hpp"
+#include "rclcpp/node_interfaces/node_topics_interface.hpp"
+#include "rclcpp/parameter.hpp"
+#include "rclcpp/qos.hpp"
+#include "rclcpp/subscription.hpp"
+#include "rclcpp/visibility_control.hpp"
+#include "rcl_interfaces/msg/parameter_event.hpp"
+
+namespace rclcpp
+{
+
+struct ParameterCallbackHandle
+{
+  RCLCPP_SMART_PTR_DEFINITIONS(ParameterCallbackHandle)
+
+  using ParameterCallbackType = std::function<void (const rclcpp::Parameter &)>;
+
+  std::string parameter_name;
+  std::string node_name;
+  ParameterCallbackType callback;
+};
+
+struct ParameterEventCallbackHandle
+{
+  RCLCPP_SMART_PTR_DEFINITIONS(ParameterEventCallbackHandle)
+
+  using ParameterEventCallbackType =
+    std::function<void (const rcl_interfaces::msg::ParameterEvent &)>;
+
+  ParameterEventCallbackType callback;
+};
+
+/// A class used to "handle" (monitor and respond to) changes to parameters.
+/**
+ * The ParameterEventHandler class allows for the monitoring of changes to node parameters,
+ * either a node's own parameters or parameters owned by other nodes in the system.
+ * Multiple parameter callbacks can be set and will be invoked when the specified parameter
+ * changes.
+ *
+ * The first step is to instantiate a ParameterEventHandler, providing a ROS node to use
+ * to create any required subscriptions:
+ *
+ *   auto param_handler = std::make_shared<rclcpp::ParameterEventHandler>(node);
+ *
+ * Next, you can supply a callback to the add_parameter_callback method, as follows:
+ *
+ *   auto cb1 = [&node](const rclcpp::Parameter & p) {
+ *      RCLCPP_INFO(
+ *        node->get_logger(),
+ *        "cb1: Received an update to parameter \"%s\" of type %s: \"%ld\"",
+ *        p.get_name().c_str(),
+ *        p.get_type_name().c_str(),
+ *        p.as_int());
+ *   };
+ *   auto handle1 = param_handler->add_parameter_callback("an_int_param", cb1);
+ *
+ * In this case, we didn't supply a node name (the third, optional, parameter) so the
+ * default will be to monitor for changes to the "an_int_param" parameter associated with
+ * the ROS node supplied in the ParameterEventHandler constructor.
+ * The callback, a lambda function in this case, simply prints out the value of the parameter.
+ *
+ * You may also monitor for changes to parameters in other nodes by supplying the node
+ * name to add_parameter_callback:
+ *
+ *   auto cb2 = [&node](const rclcpp::Parameter & p) {
+ *       RCLCPP_INFO(
+ *         node->get_logger(),
+ *         "cb2: Received an update to parameter \"%s\" of type: %s: \"%s\"",
+ *         p.get_name().c_str(),
+ *         p.get_type_name().c_str(),
+ *         p.as_string().c_str());
+ *     };
+ *   auto handle2 = param_handler->add_parameter_callback(
+ *     "some_remote_param_name", cb2, "some_remote_node_name");
+ *
+ * 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:
+ *
+ *   param_handler->remove_parameter_callback(handle2);
+ *
+ * You can also monitor for *all* parameter changes, using add_parameter_event_callback.
+ * In this case, the callback will be invoked whenever any parameter changes in the system.
+ * You are likely interested in a subset of these parameter changes, so in the callback it
+ * is convenient to use a regular expression on the node names or namespaces of interest.
+ * For example:
+ *
+ *   auto cb3 =
+ *     [fqn, remote_param_name, &node](const rcl_interfaces::msg::ParameterEvent & event) {
+ *       // Look for any updates to parameters in "/a_namespace" as well as any parameter changes
+ *       // to our own node ("this_node")
+ *       std::regex re("(/a_namespace/.*)|(/this_node)");
+ *       if (regex_match(event.node, re)) {
+ *         // Now that we know the event matches the regular expression we scanned for, we can
+ *         // use 'get_parameter_from_event' to get a specific parameter name that we're looking for
+ *         rclcpp::Parameter p;
+ *         if (rclcpp::ParameterEventsSubscriber::get_parameter_from_event(
+ *             event, p, remote_param_name, fqn))
+ *         {
+ *           RCLCPP_INFO(
+ *             node->get_logger(),
+ *             "cb3: Received an update to parameter \"%s\" of type: %s: \"%s\"",
+ *             p.get_name().c_str(),
+ *             p.get_type_name().c_str(),
+ *             p.as_string().c_str());
+ *         }
+ *
+ *         // You can also use 'get_parameter*s*_from_event' to enumerate all changes that came
+ *         // in on this event
+ *         auto params = rclcpp::ParameterEventsSubscriber::get_parameters_from_event(event);
+ *         for (auto & p : params) {
+ *           RCLCPP_INFO(
+ *             node->get_logger(),
+ *             "cb3: Received an update to parameter \"%s\" of type: %s: \"%s\"",
+ *             p.get_name().c_str(),
+ *             p.get_type_name().c_str(),
+ *             p.value_to_string().c_str());
+ *         }
+ *       }
+ *     };
+ *   auto handle3 = param_handler->add_parameter_event_callback(cb3);
+ *
+ * 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:
+ *
+ *   param_handler->remove_event_parameter_callback(handle);
+ */
+class ParameterEventHandler
+{
+public:
+  /// Construct a parameter events monitor.
+  /**
+   * \param[in] node The node to use to create any required subscribers.
+   * \param[in] qos The QoS settings to use for any subscriptions.
+   */
+  template<typename NodeT>
+  ParameterEventHandler(
+    NodeT node,
+    const rclcpp::QoS & qos =
+    rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(rmw_qos_profile_parameter_events)))
+  {
+    node_base_ = rclcpp::node_interfaces::get_node_base_interface(node);
+    auto node_topics = rclcpp::node_interfaces::get_node_topics_interface(node);
+
+    event_subscription_ = rclcpp::create_subscription<rcl_interfaces::msg::ParameterEvent>(
+      node_topics, "/parameter_events", qos,
+      std::bind(&ParameterEventHandler::event_callback, this, std::placeholders::_1));
+  }
+
+  using ParameterEventCallbackType =
+    ParameterEventCallbackHandle::ParameterEventCallbackType;
+
+  /// Set a callback for all parameter events.
+  /**
+   * This function may be called multiple times to set multiple parameter event callbacks.
+   *
+   * \param[in] callback Function callback to be invoked on parameter updates.
+   * \returns A handle used to refer to the callback.
+   */
+  RCLCPP_PUBLIC
+  ParameterEventCallbackHandle::SharedPtr
+  add_parameter_event_callback(
+    ParameterEventCallbackType callback);
+
+  /// Remove parameter event callback registered with add_parameter_event_callback.
+  /**
+   * \param[in] callback_handle Handle of the callback to remove.
+   */
+  RCLCPP_PUBLIC
+  void
+  remove_parameter_event_callback(
+    ParameterEventCallbackHandle::SharedPtr callback_handle);
+
+  using ParameterCallbackType = ParameterCallbackHandle::ParameterCallbackType;
+
+  /// Add a callback for a specified parameter.
+  /**
+   * If a node_name is not provided, defaults to the current node.
+   *
+   * \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
+  ParameterCallbackHandle::SharedPtr
+  add_parameter_callback(
+    const std::string & parameter_name,
+    ParameterCallbackType callback,
+    const std::string & node_name = "");
+
+  /// Remove a parameter callback registered with add_parameter_callback.
+  /**
+   * The parameter name and node name are inspected from the callback handle. The callback handle
+   * is erased from the list of callback handles on the {parameter_name, node_name} in the map.
+   * An error is thrown if the handle does not exist and/or was already removed.
+   *
+   * \param[in] callback_handle Handle of the callback to remove.
+   */
+  RCLCPP_PUBLIC
+  void
+  remove_parameter_callback(
+    ParameterCallbackHandle::SharedPtr callback_handle);
+
+  /// Get an rclcpp::Parameter from a parameter event.
+  /**
+   * If a node_name is not provided, defaults to the current node.
+   *
+   * \param[in] event Event msg to be inspected.
+   * \param[out] parameter Reference to rclcpp::Parameter to be assigned.
+   * \param[in] parameter_name Name of parameter.
+   * \param[in] node_name Name of node which hosts the parameter.
+   * \returns Output parameter is set with requested parameter info and returns true if
+   * requested parameter name and node is in event. Otherwise, returns false.
+   */
+  RCLCPP_PUBLIC
+  static bool
+  get_parameter_from_event(
+    const rcl_interfaces::msg::ParameterEvent & event,
+    rclcpp::Parameter & parameter,
+    const std::string parameter_name,
+    const std::string node_name = "");
+
+  /// Get an rclcpp::Parameter from parameter event
+  /**
+   * If a node_name is not provided, defaults to the current node.
+   *
+   * The user is responsible to check if the returned parameter has been properly assigned.
+   * By default, if the requested parameter is not found in the event, the returned parameter
+   * has parameter value of type rclcpp::PARAMETER_NOT_SET.
+   *
+   * \param[in] event Event msg to be inspected.
+   * \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.
+   */
+  RCLCPP_PUBLIC
+  static rclcpp::Parameter
+  get_parameter_from_event(
+    const rcl_interfaces::msg::ParameterEvent & event,
+    const std::string parameter_name,
+    const std::string node_name = "");
+
+  /// Get all rclcpp::Parameter values from a parameter event
+  /**
+   * \param[in] event Event msg to be inspected.
+   * \returns A vector rclcpp::Parameter values from the event.
+   */
+  RCLCPP_PUBLIC
+  static std::vector<rclcpp::Parameter>
+  get_parameters_from_event(
+    const rcl_interfaces::msg::ParameterEvent & event);
+
+  using CallbacksContainerType = std::list<ParameterCallbackHandle::WeakPtr>;
+
+protected:
+  /// Callback for parameter events subscriptions.
+  RCLCPP_PUBLIC
+  void
+  event_callback(const rcl_interfaces::msg::ParameterEvent & event);
+
+  // Utility function for resolving node path.
+  std::string resolve_path(const std::string & path);
+
+  // Node interface used for base functionality
+  std::shared_ptr<rclcpp::node_interfaces::NodeBaseInterface> node_base_;
+
+  // *INDENT-OFF* Uncrustify doesn't handle indented public/private labels
+  // Hash function for string pair required in std::unordered_map
+  // See: https://stackoverflow.com/questions/35985960/c-why-is-boosthash-combine-the-best-way-to-combine-hash-values
+  class StringPairHash
+  {
+  public:
+    template<typename T>
+    inline void hash_combine(std::size_t & seed, const T & v) const
+    {
+      std::hash<T> hasher;
+      seed ^= hasher(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+    }
+
+    inline size_t operator()(const std::pair<std::string, std::string> & s) const
+    {
+      size_t seed = 0;
+      hash_combine(seed, s.first);
+      hash_combine(seed, s.second);
+      return seed;
+    }
+  };
+  // *INDENT-ON*
+
+  // Map container for registered parameters
+  std::unordered_map<
+    std::pair<std::string, std::string>,
+    CallbacksContainerType,
+    StringPairHash
+  > parameter_callbacks_;
+
+  rclcpp::Subscription<rcl_interfaces::msg::ParameterEvent>::SharedPtr event_subscription_;
+
+  std::list<ParameterEventCallbackHandle::WeakPtr> event_callbacks_;
+
+  std::recursive_mutex mutex_;
+};
+
+}  // namespace rclcpp
+
+#endif  // RCLCPP__PARAMETER_EVENT_HANDLER_HPP_

rclcpp/include/rclcpp/parameter_events_filter.hpp

@@ -37,7 +37,7 @@ public:
   RCLCPP_SMART_PTR_DEFINITIONS(ParameterEventsFilter)
   enum class EventType {NEW, DELETED, CHANGED};  ///< An enum for the type of event.
   /// Used for the listed results
-  using EventPair = std::pair<EventType, rcl_interfaces::msg::Parameter *>;
+  using EventPair = std::pair<EventType, const rcl_interfaces::msg::Parameter *>;
 
   /// Construct a filtered view of a parameter event.
   /**
@@ -60,7 +60,7 @@ public:
    */
   RCLCPP_PUBLIC
   ParameterEventsFilter(
-    rcl_interfaces::msg::ParameterEvent::SharedPtr event,
+    std::shared_ptr<const rcl_interfaces::msg::ParameterEvent> event,
     const std::vector<std::string> & names,
     const std::vector<EventType> & types);
 
@@ -74,7 +74,7 @@ public:
 private:
   // access only allowed via const accessor.
   std::vector<EventPair> result_;  ///< Storage of the resultant vector
-  rcl_interfaces::msg::ParameterEvent::SharedPtr event_;  ///< Keep event in scope
+  std::shared_ptr<const rcl_interfaces::msg::ParameterEvent> event_;  ///< Keep event in scope
 };
 
 }  // namespace rclcpp

rclcpp/include/rclcpp/parameter_map.hpp

@@ -15,6 +15,7 @@
 #ifndef RCLCPP__PARAMETER_MAP_HPP_
 #define RCLCPP__PARAMETER_MAP_HPP_
 
+#include <rcl_yaml_param_parser/parser.h>
 #include <rcl_yaml_param_parser/types.h>
 
 #include <string>
@@ -48,6 +49,14 @@ RCLCPP_PUBLIC
 ParameterValue
 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.
+/// \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);
+
 }  // namespace rclcpp
 
 #endif  // RCLCPP__PARAMETER_MAP_HPP_

rclcpp/include/rclcpp/publisher.hpp

@@ -40,6 +40,8 @@
 #include "rclcpp/type_support_decl.hpp"
 #include "rclcpp/visibility_control.hpp"
 
+#include "tracetools/tracetools.h"
+
 namespace rclcpp
 {
 
@@ -261,7 +263,7 @@ public:
     if (this->can_loan_messages()) {
       // we release the ownership from the rclpp::LoanedMessage instance
       // and let the middleware clean up the memory.
-      this->do_loaned_message_publish(loaned_msg.release());
+      this->do_loaned_message_publish(std::move(loaned_msg.release()));
     } else {
       // we don't release the ownership, let the middleware copy the ros message
       // and thus the destructor of rclcpp::LoanedMessage cleans up the memory.
@@ -279,6 +281,10 @@ protected:
   void
   do_inter_process_publish(const MessageT & msg)
   {
+    TRACEPOINT(
+      rclcpp_publish,
+      static_cast<const void *>(publisher_handle_.get()),
+      static_cast<const void *>(&msg));
     auto status = rcl_publish(publisher_handle_.get(), &msg, nullptr);
 
     if (RCL_RET_PUBLISHER_INVALID == status) {
@@ -310,9 +316,9 @@ protected:
   }
 
   void
-  do_loaned_message_publish(MessageT * msg)
+  do_loaned_message_publish(std::unique_ptr<MessageT, std::function<void(MessageT *)>> msg)
   {
-    auto status = rcl_publish_loaned_message(publisher_handle_.get(), msg, nullptr);
+    auto status = rcl_publish_loaned_message(publisher_handle_.get(), msg.get(), nullptr);
 
     if (RCL_RET_PUBLISHER_INVALID == status) {
       rcl_reset_error();  // next call will reset error message if not context

rclcpp/include/rclcpp/publisher_base.hpp

@@ -28,6 +28,7 @@
 #include "rcl/publisher.h"
 
 #include "rclcpp/macros.hpp"
+#include "rclcpp/network_flow_endpoint.hpp"
 #include "rclcpp/qos.hpp"
 #include "rclcpp/qos_event.hpp"
 #include "rclcpp/type_support_decl.hpp"
@@ -193,6 +194,15 @@ public:
     uint64_t intra_process_publisher_id,
     IntraProcessManagerSharedPtr ipm);
 
+  /// Get network flow endpoints
+  /**
+   * Describes network flow endpoints that this publisher is sending messages out on
+   * \return vector of NetworkFlowEndpoint
+   */
+  RCLCPP_PUBLIC
+  std::vector<rclcpp::NetworkFlowEndpoint>
+  get_network_flow_endpoints() const;
+
 protected:
   template<typename EventCallbackT>
   void

rclcpp/include/rclcpp/publisher_options.hpp

@@ -26,6 +26,7 @@
 #include "rclcpp/intra_process_setting.hpp"
 #include "rclcpp/qos.hpp"
 #include "rclcpp/qos_event.hpp"
+#include "rclcpp/qos_overriding_options.hpp"
 
 namespace rclcpp
 {
@@ -44,12 +45,19 @@ struct PublisherOptionsBase
   /// Whether or not to use default callbacks when user doesn't supply any in event_callbacks
   bool use_default_callbacks = true;
 
+  /// Require middleware to generate unique network flow endpoints
+  /// Disabled by default
+  rmw_unique_network_flow_endpoints_requirement_t require_unique_network_flow_endpoints =
+    RMW_UNIQUE_NETWORK_FLOW_ENDPOINTS_NOT_REQUIRED;
+
   /// Callback group in which the waitable items from the publisher should be placed.
   std::shared_ptr<rclcpp::CallbackGroup> callback_group;
 
   /// Optional RMW implementation specific payload to be used during creation of the publisher.
   std::shared_ptr<rclcpp::detail::RMWImplementationSpecificPublisherPayload>
   rmw_implementation_payload = nullptr;
+
+  QosOverridingOptions qos_overriding_options;
 };
 
 /// Structure containing optional configuration for Publishers.
@@ -72,11 +80,10 @@ struct PublisherOptionsWithAllocator : public PublisherOptionsBase
   to_rcl_publisher_options(const rclcpp::QoS & qos) const
   {
     rcl_publisher_options_t result = rcl_publisher_get_default_options();
-    using AllocatorTraits = std::allocator_traits<Allocator>;
-    using MessageAllocatorT = typename AllocatorTraits::template rebind_alloc<MessageT>;
-    auto message_alloc = std::make_shared<MessageAllocatorT>(*this->get_allocator().get());
-    result.allocator = rclcpp::allocator::get_rcl_allocator<MessageT>(*message_alloc);
+    result.allocator = rclcpp::allocator::get_rcl_allocator(*this->get_allocator());
     result.qos = qos.get_rmw_qos_profile();
+    result.rmw_publisher_options.require_unique_network_flow_endpoints =
+      this->require_unique_network_flow_endpoints;
 
     // Apply payload to rcl_publisher_options if necessary.
     if (rmw_implementation_payload && rmw_implementation_payload->has_been_customized()) {
@@ -92,12 +99,7 @@ struct PublisherOptionsWithAllocator : public PublisherOptionsBase
   get_allocator() const
   {
     if (!this->allocator) {
-      // TODO(wjwwood): I would like to use the commented line instead, but
-      //   cppcheck 1.89 fails with:
-      //     Syntax Error: AST broken, binary operator '>' doesn't have two operands.
-      // return std::make_shared<Allocator>();
-      std::shared_ptr<Allocator> tmp(new Allocator());
-      return tmp;
+      return std::make_shared<Allocator>();
     }
     return this->allocator;
   }

rclcpp/include/rclcpp/qos.hpp

@@ -18,6 +18,7 @@
 #include <string>
 
 #include "rclcpp/duration.hpp"
+#include "rclcpp/exceptions.hpp"
 #include "rclcpp/visibility_control.hpp"
 #include "rcl/logging_rosout.h"
 #include "rmw/incompatible_qos_events_statuses.h"
@@ -30,6 +31,45 @@ namespace rclcpp
 RCLCPP_PUBLIC
 std::string qos_policy_name_from_kind(rmw_qos_policy_kind_t policy_kind);
 
+enum class HistoryPolicy
+{
+  KeepLast = RMW_QOS_POLICY_HISTORY_KEEP_LAST,
+  KeepAll = RMW_QOS_POLICY_HISTORY_KEEP_ALL,
+  SystemDefault = RMW_QOS_POLICY_HISTORY_SYSTEM_DEFAULT,
+  Unknown = RMW_QOS_POLICY_HISTORY_UNKNOWN,
+};
+
+enum class ReliabilityPolicy
+{
+  BestEffort = RMW_QOS_POLICY_RELIABILITY_BEST_EFFORT,
+  Reliable = RMW_QOS_POLICY_RELIABILITY_RELIABLE,
+  SystemDefault = RMW_QOS_POLICY_RELIABILITY_SYSTEM_DEFAULT,
+  Unknown = RMW_QOS_POLICY_RELIABILITY_UNKNOWN,
+};
+
+enum class DurabilityPolicy
+{
+  Volatile = RMW_QOS_POLICY_DURABILITY_VOLATILE,
+  TransientLocal = RMW_QOS_POLICY_DURABILITY_TRANSIENT_LOCAL,
+  SystemDefault = RMW_QOS_POLICY_DURABILITY_SYSTEM_DEFAULT,
+  Unknown = RMW_QOS_POLICY_DURABILITY_UNKNOWN,
+};
+
+enum class LivelinessPolicy
+{
+  Automatic = RMW_QOS_POLICY_LIVELINESS_AUTOMATIC,
+  ManualByTopic = RMW_QOS_POLICY_LIVELINESS_MANUAL_BY_TOPIC,
+  SystemDefault = RMW_QOS_POLICY_LIVELINESS_SYSTEM_DEFAULT,
+  Unknown = RMW_QOS_POLICY_LIVELINESS_UNKNOWN,
+};
+
+enum class QoSCompatibility
+{
+  Ok = RMW_QOS_COMPATIBILITY_OK,
+  Warning = RMW_QOS_COMPATIBILITY_WARNING,
+  Error = RMW_QOS_COMPATIBILITY_ERROR,
+};
+
 /// QoS initialization values, cannot be created directly, use KeepAll or KeepLast instead.
 struct RCLCPP_PUBLIC QoSInitialization
 {
@@ -58,10 +98,32 @@ struct RCLCPP_PUBLIC KeepLast : public rclcpp::QoSInitialization
 };
 
 /// Encapsulation of Quality of Service settings.
+/**
+ * Quality of Service settings control the behavior of publishers, subscriptions,
+ * and other entities, and includes things like how data is sent or resent,
+ * how data is buffered on the publishing and subscribing side, and other things.
+ * See:
+ *   <a href="https://docs.ros.org/en/rolling/Concepts/About-Quality-of-Service-Settings.html">
+ *     https://docs.ros.org/en/rolling/Concepts/About-Quality-of-Service-Settings.html
+ *   </a>
+ */
 class RCLCPP_PUBLIC QoS
 {
 public:
-  /// Constructor which allows you to construct a QoS by giving the only required settings.
+  /// Create a QoS by specifying only the history policy and history depth.
+  /**
+   * When using the default initial profile, the defaults will include:
+   *
+   *   - \link rclcpp::ReliabilityPolicy::Reliable ReliabilityPolicy::Reliable\endlink
+   *   - \link rclcpp::DurabilityPolicy::Volatile DurabilityPolicy::Volatile\endlink
+   *
+   * See rmw_qos_profile_default for a full list of default settings.
+   * If some other rmw_qos_profile_t is passed to initial_profile, then the defaults will derive from
+   * that profile instead.
+   *
+   * \param[in] qos_initialization Specifies history policy and history depth.
+   * \param[in] initial_profile The rmw_qos_profile_t instance on which to base the default settings.
+   */
   explicit
   QoS(
     const QoSInitialization & qos_initialization,
@@ -69,7 +131,11 @@ public:
 
   /// Conversion constructor to ease construction in the common case of just specifying depth.
   /**
-   * Convenience constructor, equivalent to QoS(KeepLast(history_depth)).
+   * This is a convenience constructor that calls QoS(KeepLast(history_depth)).
+   *
+   * \param[in] history_depth How many messages can be queued when publishing
+   *   with a Publisher, or how many messages can be queued before being replaced
+   *   by a Subscription.
    */
   // cppcheck-suppress noExplicitConstructor
   QoS(size_t history_depth);  // NOLINT(runtime/explicit): conversion constructor
@@ -82,6 +148,10 @@ public:
   const rmw_qos_profile_t &
   get_rmw_qos_profile() const;
 
+  /// Set the history policy.
+  QoS &
+  history(HistoryPolicy history);
+
   /// Set the history policy.
   QoS &
   history(rmw_qos_history_policy_t history);
@@ -98,6 +168,10 @@ public:
   QoS &
   reliability(rmw_qos_reliability_policy_t reliability);
 
+  /// Set the reliability setting.
+  QoS &
+  reliability(ReliabilityPolicy reliability);
+
   /// Set the reliability setting to reliable.
   QoS &
   reliable();
@@ -110,6 +184,10 @@ public:
   QoS &
   durability(rmw_qos_durability_policy_t durability);
 
+  /// Set the durability setting.
+  QoS &
+  durability(DurabilityPolicy durability);
+
   /// Set the durability setting to volatile.
   /**
     * Note that this cannot be named `volatile` because it is a C++ keyword.
@@ -141,6 +219,10 @@ public:
   QoS &
   liveliness(rmw_qos_liveliness_policy_t liveliness);
 
+  /// Set the liveliness setting.
+  QoS &
+  liveliness(LivelinessPolicy liveliness);
+
   /// Set the liveliness_lease_duration setting.
   QoS &
   liveliness_lease_duration(rmw_time_t liveliness_lease_duration);
@@ -153,6 +235,42 @@ public:
   QoS &
   avoid_ros_namespace_conventions(bool avoid_ros_namespace_conventions);
 
+  /// Get the history qos policy.
+  HistoryPolicy
+  history() const;
+
+  /// Get the history depth.
+  size_t
+  depth() const;
+
+  /// Get the reliability policy.
+  ReliabilityPolicy
+  reliability() const;
+
+  /// Get the durability policy.
+  DurabilityPolicy
+  durability() const;
+
+  /// Get the deadline duration setting.
+  rclcpp::Duration
+  deadline() const;
+
+  /// Get the lifespan duration setting.
+  rclcpp::Duration
+  lifespan() const;
+
+  /// Get the liveliness policy.
+  LivelinessPolicy
+  liveliness() const;
+
+  /// Get the liveliness lease duration setting.
+  rclcpp::Duration
+  liveliness_lease_duration() const;
+
+  /// Get the `avoid ros namespace convention` setting.
+  bool
+  avoid_ros_namespace_conventions() const;
+
 private:
   rmw_qos_profile_t rmw_qos_profile_;
 };
@@ -163,6 +281,61 @@ bool operator==(const QoS & left, const QoS & right);
 RCLCPP_PUBLIC
 bool operator!=(const QoS & left, const QoS & right);
 
+/// Result type for checking QoS compatibility
+/**
+ * \see rclcpp::qos_check_compatible()
+ */
+struct QoSCheckCompatibleResult
+{
+  /// Compatibility result.
+  QoSCompatibility compatibility;
+
+  /// Reason for a (possible) incompatibility.
+  /**
+   * Set if compatiblity is QoSCompatibility::Warning or QoSCompatiblity::Error.
+   * Not set if the QoS profiles are compatible.
+   */
+  std::string reason;
+};
+
+/// Check if two QoS profiles are compatible.
+/**
+ * Two QoS profiles are compatible if a publisher and subcription
+ * using the QoS policies can communicate with each other.
+ *
+ * If any policies have value "system default" or "unknown" then it is possible that
+ * compatiblity cannot be determined.
+ * In this case, the value QoSCompatility::Warning is set as part of
+ * the returned structure.
+ *
+ * Example usage:
+ *
+ * ```cpp
+ * rclcpp::QoSCheckCompatibleResult result = rclcpp::qos_check_compatible(
+ *   publisher_qos, subscription_qos);
+ * if (rclcpp::QoSCompatibility::Error != result.compatibility) {
+ *   // QoS not compatible ...
+ *   // result.reason contains info about the incompatibility
+ * } else if (rclcpp::QoSCompatibility::Warning != result.compatibility) {
+ *   // QoS may not be compatible ...
+ *   // result.reason contains info about the possible incompatibility
+ * }
+ * ```
+ *
+ * \param[in] publisher_qos: The QoS profile for a publisher.
+ * \param[in] subscription_qos: The QoS profile for a subscription.
+ * \return Struct with compatiblity set to QoSCompatibility::Ok if the QoS profiles are
+ *   compatible, or
+ * \return Struct with compatibility set to QoSCompatibility::Warning if there is a chance
+ *   the QoS profiles are not compatible, or
+ * \return Struct with compatibility set to QoSCompatibility::Error if the QoS profiles are
+ *   not compatible.
+ * \throws rclcpp::exceptions::QoSCheckCompatibilityException if an unexpected error occurs.
+ */
+RCLCPP_PUBLIC
+QoSCheckCompatibleResult
+qos_check_compatible(const QoS & publisher_qos, const QoS & subscription_qos);
+
 /**
  * Clock QoS class
  *    - History: Keep last,

rclcpp/include/rclcpp/qos_event.hpp

@@ -16,6 +16,8 @@
 #define RCLCPP__QOS_EVENT_HPP_
 
 #include <functional>
+#include <memory>
+#include <stdexcept>
 #include <string>
 
 #include "rcl/error_handling.h"
@@ -131,21 +133,31 @@ public:
     }
   }
 
-  /// Execute any entities of the Waitable that are ready.
-  void
-  execute() override
+  /// Take data so that the callback cannot be scheduled again
+  std::shared_ptr<void>
+  take_data() override
   {
     EventCallbackInfoT callback_info;
-
     rcl_ret_t ret = rcl_take_event(&event_handle_, &callback_info);
     if (ret != RCL_RET_OK) {
       RCUTILS_LOG_ERROR_NAMED(
         "rclcpp",
         "Couldn't take event info: %s", rcl_get_error_string().str);
-      return;
+      return nullptr;
     }
+    return std::static_pointer_cast<void>(std::make_shared<EventCallbackInfoT>(callback_info));
+  }
 
-    event_callback_(callback_info);
+  /// Execute any entities of the Waitable that are ready.
+  void
+  execute(std::shared_ptr<void> & data) override
+  {
+    if (!data) {
+      throw std::runtime_error("'data' is empty");
+    }
+    auto callback_ptr = std::static_pointer_cast<EventCallbackInfoT>(data);
+    event_callback_(*callback_ptr);
+    callback_ptr.reset();
   }
 
 private:

rclcpp/include/rclcpp/qos_overriding_options.hpp

@@ -0,0 +1,154 @@
+// Copyright 2020 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP__QOS_OVERRIDING_OPTIONS_HPP_
+#define RCLCPP__QOS_OVERRIDING_OPTIONS_HPP_
+
+#include <functional>
+#include <initializer_list>
+#include <ostream>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "rclcpp/qos.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+#include "rcl_interfaces/msg/set_parameters_result.hpp"
+#include "rmw/qos_policy_kind.h"
+
+namespace rclcpp
+{
+
+enum class RCLCPP_PUBLIC_TYPE QosPolicyKind
+{
+  AvoidRosNamespaceConventions = RMW_QOS_POLICY_AVOID_ROS_NAMESPACE_CONVENTIONS,
+  Deadline = RMW_QOS_POLICY_DEADLINE,
+  Depth = RMW_QOS_POLICY_DEPTH,
+  Durability = RMW_QOS_POLICY_DURABILITY,
+  History = RMW_QOS_POLICY_HISTORY,
+  Lifespan = RMW_QOS_POLICY_LIFESPAN,
+  Liveliness = RMW_QOS_POLICY_LIVELINESS,
+  LivelinessLeaseDuration = RMW_QOS_POLICY_LIVELINESS_LEASE_DURATION,
+  Reliability = RMW_QOS_POLICY_RELIABILITY,
+  Invalid = RMW_QOS_POLICY_INVALID,
+};
+
+RCLCPP_PUBLIC
+const char *
+qos_policy_kind_to_cstr(const QosPolicyKind & qpk);
+
+RCLCPP_PUBLIC
+std::ostream &
+operator<<(std::ostream & os, const QosPolicyKind & qpk);
+
+using QosCallbackResult = rcl_interfaces::msg::SetParametersResult;
+using QosCallback = std::function<QosCallbackResult(const rclcpp::QoS &)>;
+
+namespace detail
+{
+// forward declare
+template<typename T>
+class QosParameters;
+}
+
+/// Options that are passed in subscription/publisher constructor to specify QoSConfigurability.
+/**
+ * This options struct allows configuring:
+ * - Which policy kinds will have declared parameters.
+ * - An optional callback, that will be called to validate the final qos profile.
+ * - An optional id. In the case that different qos are desired for two publishers/subscriptions in
+ *   the same topic, this id will allow disambiguating them.
+ *
+ * Example parameter file:
+ *
+ * ```yaml
+ * my_node_name:
+ *  ros__parameters:
+ *    qos_overrides:
+ *      /my/topic/name:
+ *        publisher:  # publisher without provided id
+ *          reliability: reliable
+ *          depth: 100
+ *        publisher_my_id:  # publisher with `id="my_id"
+ *          reliability: reliable
+ *          depth: 10
+ * ```
+ */
+class QosOverridingOptions
+{
+public:
+  /// Default constructor, no overrides allowed.
+  RCLCPP_PUBLIC
+  QosOverridingOptions() = default;
+
+  /// Construct passing a list of QoS policies and a verification callback.
+  /**
+   * This constructor is implicit, e.g.:
+   * ```cpp
+   * node->create_publisher(
+   *   "topic_name",
+   *   default_qos_profile,
+   *   {
+   *     {QosPolicyKind::Reliability},
+   *     [] (auto && qos) {return check_qos_validity(qos)},
+   *     "my_id"
+   *   });
+   * ```
+   * \param policy_kinds list of policy kinds that will be reconfigurable.
+   * \param validation_callback callbak that will be called to validate the validity of
+   *   the qos profile set by the user.
+   * \param id id of the entity.
+   */
+  RCLCPP_PUBLIC
+  QosOverridingOptions(
+    std::initializer_list<QosPolicyKind> policy_kinds,
+    QosCallback validation_callback = nullptr,
+    std::string id = {});
+
+  RCLCPP_PUBLIC
+  const std::string &
+  get_id() const;
+
+  RCLCPP_PUBLIC
+  const std::vector<QosPolicyKind> &
+  get_policy_kinds() const;
+
+  RCLCPP_PUBLIC
+  const QosCallback &
+  get_validation_callback() const;
+
+  /// Construct passing a list of QoS policies and a verification callback.
+  /**
+   * Same as `QosOverridingOptions` constructor, but only declares the default policies:
+   *
+   * History, Depth, Reliability.
+   */
+  RCLCPP_PUBLIC
+  static
+  QosOverridingOptions
+  with_default_policies(QosCallback validation_callback = nullptr, std::string id = {});
+
+private:
+  /// \internal Id of the entity requesting to create parameters.
+  std::string id_;
+  /// \internal Policy kinds that are allowed to be reconfigured.
+  std::vector<QosPolicyKind> policy_kinds_;
+  /// \internal Validation callback that will be called to verify the profile.
+  QosCallback validation_callback_;
+};
+
+}  // namespace rclcpp
+
+#endif  // RCLCPP__QOS_OVERRIDING_OPTIONS_HPP_

rclcpp/include/rclcpp/rclcpp.hpp

@@ -117,6 +117,15 @@
  * - Allocator related items:
  *   - rclcpp/allocator/allocator_common.hpp
  *   - rclcpp/allocator/allocator_deleter.hpp
+ * - Generic publisher
+ *   - rclcpp::Node::create_generic_publisher()
+ *   - rclcpp::GenericPublisher
+ *   - rclcpp::GenericPublisher::publish()
+ *   - rclcpp/generic_publisher.hpp
+ * - Generic subscription
+ *   - rclcpp::Node::create_generic_subscription()
+ *   - rclcpp::GenericSubscription
+ *   - rclcpp/generic_subscription.hpp
  * - Memory management tools:
  *   - rclcpp/memory_strategies.hpp
  *   - rclcpp/memory_strategy.hpp
@@ -134,6 +143,7 @@
  *   - rclcpp/scope_exit.hpp
  *   - rclcpp/time.hpp
  *   - rclcpp/utilities.hpp
+ *   - rclcpp/typesupport_helpers.hpp
  *   - rclcpp/visibility_control.hpp
  */
 
@@ -147,14 +157,15 @@
 #include "rclcpp/guard_condition.hpp"
 #include "rclcpp/logging.hpp"
 #include "rclcpp/node.hpp"
-#include "rclcpp/parameter.hpp"
 #include "rclcpp/parameter_client.hpp"
+#include "rclcpp/parameter_event_handler.hpp"
+#include "rclcpp/parameter.hpp"
 #include "rclcpp/parameter_service.hpp"
 #include "rclcpp/rate.hpp"
 #include "rclcpp/time.hpp"
 #include "rclcpp/utilities.hpp"
 #include "rclcpp/visibility_control.hpp"
-#include "rclcpp/wait_set.hpp"
 #include "rclcpp/waitable.hpp"
+#include "rclcpp/wait_set.hpp"
 
 #endif  // RCLCPP__RCLCPP_HPP_

rclcpp/include/rclcpp/service.hpp

@@ -180,7 +180,7 @@ public:
     std::weak_ptr<rcl_node_t> weak_node_handle(node_handle_);
     // rcl does the static memory allocation here
     service_handle_ = std::shared_ptr<rcl_service_t>(
-      new rcl_service_t, [weak_node_handle](rcl_service_t * service)
+      new rcl_service_t, [weak_node_handle, service_name](rcl_service_t * service)
       {
         auto handle = weak_node_handle.lock();
         if (handle) {
@@ -192,10 +192,10 @@ public:
             rcl_reset_error();
           }
         } else {
-          RCLCPP_ERROR(
+          RCLCPP_ERROR_STREAM(
             rclcpp::get_logger("rclcpp"),
-            "Error in destruction of rcl service handle: "
-            "the Node Handle was destructed too early. You will leak memory");
+            "Error in destruction of rcl service handle " << service_name <<
+              ": the Node Handle was destructed too early. You will leak memory");
         }
         delete service;
       });
@@ -349,15 +349,6 @@ public:
     send_response(*request_header, *response);
   }
 
-  [[deprecated("use the send_response() which takes references instead of shared pointers")]]
-  void
-  send_response(
-    std::shared_ptr<rmw_request_id_t> req_id,
-    std::shared_ptr<typename ServiceT::Response> response)
-  {
-    send_response(*req_id, *response);
-  }
-
   void
   send_response(rmw_request_id_t & req_id, typename ServiceT::Response & response)
   {

rclcpp/include/rclcpp/strategies/allocator_memory_strategy.hpp

@@ -437,7 +437,7 @@ public:
 
   rcl_allocator_t get_allocator() override
   {
-    return rclcpp::allocator::get_rcl_allocator<void *, VoidAlloc>(*allocator_.get());
+    return rclcpp::allocator::get_rcl_allocator(*allocator_.get());
   }
 
   size_t number_of_ready_subscriptions() const override

rclcpp/include/rclcpp/subscription.hpp

@@ -171,11 +171,7 @@ public:
 
       // First create a SubscriptionIntraProcess which will be given to the intra-process manager.
       auto context = node_base->get_context();
-      using SubscriptionIntraProcessT = rclcpp::experimental::SubscriptionIntraProcess<
-        CallbackMessageT,
-        AllocatorT,
-        typename MessageUniquePtr::deleter_type>;
-      auto subscription_intra_process = std::make_shared<SubscriptionIntraProcessT>(
+      subscription_intra_process_ = std::make_shared<SubscriptionIntraProcessT>(
         callback,
         options.get_allocator(),
         context,
@@ -185,12 +181,12 @@ public:
       TRACEPOINT(
         rclcpp_subscription_init,
         static_cast<const void *>(get_subscription_handle().get()),
-        static_cast<const void *>(subscription_intra_process.get()));
+        static_cast<const void *>(subscription_intra_process_.get()));
 
       // Add it to the intra process manager.
       using rclcpp::experimental::IntraProcessManager;
       auto ipm = context->get_sub_context<IntraProcessManager>();
-      uint64_t intra_process_subscription_id = ipm->add_subscription(subscription_intra_process);
+      uint64_t intra_process_subscription_id = ipm->add_subscription(subscription_intra_process_);
       this->setup_intra_process(intra_process_subscription_id, ipm);
     }
 
@@ -277,11 +273,18 @@ public:
       return;
     }
     auto typed_message = std::static_pointer_cast<CallbackMessageT>(message);
+
+    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(typed_message, message_info);
 
     if (subscription_topic_statistics_) {
-      const auto nanos = std::chrono::time_point_cast<std::chrono::nanoseconds>(
-        std::chrono::system_clock::now());
+      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);
     }
@@ -340,6 +343,11 @@ private:
     message_memory_strategy_;
   /// Component which computes and publishes topic statistics for this subscriber
   SubscriptionTopicStatisticsSharedPtr subscription_topic_statistics_{nullptr};
+  using SubscriptionIntraProcessT = rclcpp::experimental::SubscriptionIntraProcess<
+    CallbackMessageT,
+    AllocatorT,
+    typename MessageUniquePtr::deleter_type>;
+  std::shared_ptr<SubscriptionIntraProcessT> subscription_intra_process_;
 };
 
 }  // namespace rclcpp

rclcpp/include/rclcpp/subscription_base.hpp

@@ -31,6 +31,7 @@
 #include "rclcpp/experimental/subscription_intra_process_base.hpp"
 #include "rclcpp/macros.hpp"
 #include "rclcpp/message_info.hpp"
+#include "rclcpp/network_flow_endpoint.hpp"
 #include "rclcpp/qos.hpp"
 #include "rclcpp/qos_event.hpp"
 #include "rclcpp/serialized_message.hpp"
@@ -61,8 +62,11 @@ class SubscriptionBase : public std::enable_shared_from_this<SubscriptionBase>
 public:
   RCLCPP_SMART_PTR_DEFINITIONS_NOT_COPYABLE(SubscriptionBase)
 
-  /// Default constructor.
+  /// Constructor.
   /**
+   * This accepts rcl_subscription_options_t instead of rclcpp::SubscriptionOptions because
+   * rclcpp::SubscriptionOptions::to_rcl_subscription_options depends on the message type.
+   *
    * \param[in] node_base NodeBaseInterface pointer used in parts of the setup.
    * \param[in] type_support_handle rosidl type support struct, for the Message type of the topic.
    * \param[in] topic_name Name of the topic to subscribe to.
@@ -77,7 +81,7 @@ public:
     const rcl_subscription_options_t & subscription_options,
     bool is_serialized = false);
 
-  /// Default destructor.
+  /// Destructor.
   RCLCPP_PUBLIC
   virtual ~SubscriptionBase();
 
@@ -263,6 +267,15 @@ public:
   bool
   exchange_in_use_by_wait_set_state(void * pointer_to_subscription_part, bool in_use_state);
 
+  /// Get network flow endpoints
+  /**
+   * Describes network flow endpoints that this subscription is receiving messages on
+   * \return vector of NetworkFlowEndpoint
+   */
+  RCLCPP_PUBLIC
+  std::vector<rclcpp::NetworkFlowEndpoint>
+  get_network_flow_endpoints() const;
+
 protected:
   template<typename EventCallbackT>
   void

rclcpp/include/rclcpp/subscription_factory.hpp

@@ -93,7 +93,7 @@ create_subscription_factory(
   auto allocator = options.get_allocator();
 
   using rclcpp::AnySubscriptionCallback;
-  AnySubscriptionCallback<CallbackMessageT, AllocatorT> any_subscription_callback(allocator);
+  AnySubscriptionCallback<CallbackMessageT, AllocatorT> any_subscription_callback(*allocator);
   any_subscription_callback.set(std::forward<CallbackT>(callback));
 
   SubscriptionFactory factory {

rclcpp/include/rclcpp/subscription_options.hpp

@@ -26,6 +26,7 @@
 #include "rclcpp/intra_process_setting.hpp"
 #include "rclcpp/qos.hpp"
 #include "rclcpp/qos_event.hpp"
+#include "rclcpp/qos_overriding_options.hpp"
 #include "rclcpp/topic_statistics_state.hpp"
 #include "rclcpp/visibility_control.hpp"
 
@@ -44,6 +45,11 @@ struct SubscriptionOptionsBase
   /// True to ignore local publications.
   bool ignore_local_publications = false;
 
+  /// Require middleware to generate unique network flow endpoints
+  /// Disabled by default
+  rmw_unique_network_flow_endpoints_requirement_t require_unique_network_flow_endpoints =
+    RMW_UNIQUE_NETWORK_FLOW_ENDPOINTS_NOT_REQUIRED;
+
   /// The callback group for this subscription. NULL to use the default callback group.
   rclcpp::CallbackGroup::SharedPtr callback_group = nullptr;
 
@@ -72,6 +78,8 @@ struct SubscriptionOptionsBase
   };
 
   TopicStatisticsOptions topic_stats_options;
+
+  QosOverridingOptions qos_overriding_options;
 };
 
 /// Structure containing optional configuration for Subscriptions.
@@ -99,12 +107,11 @@ struct SubscriptionOptionsWithAllocator : public SubscriptionOptionsBase
   to_rcl_subscription_options(const rclcpp::QoS & qos) const
   {
     rcl_subscription_options_t result = rcl_subscription_get_default_options();
-    using AllocatorTraits = std::allocator_traits<Allocator>;
-    using MessageAllocatorT = typename AllocatorTraits::template rebind_alloc<MessageT>;
-    auto message_alloc = std::make_shared<MessageAllocatorT>(*allocator.get());
-    result.allocator = allocator::get_rcl_allocator<MessageT>(*message_alloc);
+    result.allocator = rclcpp::allocator::get_rcl_allocator(*this->get_allocator());
     result.qos = qos.get_rmw_qos_profile();
     result.rmw_subscription_options.ignore_local_publications = this->ignore_local_publications;
+    result.rmw_subscription_options.require_unique_network_flow_endpoints =
+      this->require_unique_network_flow_endpoints;
 
     // Apply payload to rcl_subscription_options if necessary.
     if (rmw_implementation_payload && rmw_implementation_payload->has_been_customized()) {

rclcpp/include/rclcpp/subscription_traits.hpp

@@ -64,7 +64,7 @@ struct is_serialized_callback
 template<typename MessageT>
 struct extract_message_type
 {
-  using type = typename std::remove_cv<MessageT>::type;
+  using type = typename std::remove_cv_t<std::remove_reference_t<MessageT>>;
 };
 
 template<typename MessageT>

rclcpp/include/rclcpp/time_source.hpp

@@ -25,6 +25,7 @@
 #include "rcl_interfaces/msg/parameter_event.hpp"
 
 #include "rclcpp/node.hpp"
+#include "rclcpp/executors.hpp"
 #include "rclcpp/node_interfaces/node_parameters_interface.hpp"
 
 
@@ -32,6 +33,20 @@ namespace rclcpp
 {
 class Clock;
 
+/**
+ * Time source that will drive the attached clocks.
+ *
+ * If the attached node `use_sim_time` parameter is `true`, the attached clocks will
+ * be updated based on messages received.
+ *
+ * The subscription to the clock topic created by the time source can have it's qos reconfigured
+ * using parameter overrides, particularly the following ones are accepted:
+ *
+ * - qos_overrides./clock.depth
+ * - qos_overrides./clock.durability
+ * - qos_overrides./clock.history
+ * - qos_overrides./clock.reliability
+ */
 class TimeSource
 {
 public:
@@ -43,7 +58,10 @@ public:
    * \param qos QoS that will be used when creating a `/clock` subscription.
    */
   RCLCPP_PUBLIC
-  explicit TimeSource(rclcpp::Node::SharedPtr node, const rclcpp::QoS & qos = rclcpp::ClockQoS());
+  explicit TimeSource(
+    rclcpp::Node::SharedPtr node,
+    const rclcpp::QoS & qos = rclcpp::ClockQoS(),
+    bool use_clock_thread = true);
 
   /// Empty constructor
   /**
@@ -52,7 +70,9 @@ public:
    * \param qos QoS that will be used when creating a `/clock` subscription.
    */
   RCLCPP_PUBLIC
-  explicit TimeSource(const rclcpp::QoS & qos = rclcpp::ClockQoS());
+  explicit TimeSource(
+    const rclcpp::QoS & qos = rclcpp::ClockQoS(),
+    bool use_clock_thread = true);
 
   /// Attack node to the time source.
   /**
@@ -104,6 +124,11 @@ public:
   RCLCPP_PUBLIC
   ~TimeSource();
 
+protected:
+  // Dedicated thread for clock subscription.
+  bool use_clock_thread_;
+  std::thread clock_executor_thread_;
+
 private:
   // Preserve the node reference
   rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_base_;
@@ -126,9 +151,12 @@ private:
   using SubscriptionT = rclcpp::Subscription<MessageT, Alloc>;
   std::shared_ptr<SubscriptionT> clock_subscription_{nullptr};
   std::mutex clock_sub_lock_;
+  rclcpp::CallbackGroup::SharedPtr clock_callback_group_;
+  rclcpp::executors::SingleThreadedExecutor::SharedPtr clock_executor_;
+  std::promise<void> cancel_clock_executor_promise_;
 
   // The clock callback itself
-  void clock_cb(const rosgraph_msgs::msg::Clock::SharedPtr msg);
+  void clock_cb(std::shared_ptr<const rosgraph_msgs::msg::Clock> msg);
 
   // Create the subscription for the clock topic
   void create_clock_sub();
@@ -142,7 +170,7 @@ private:
   std::shared_ptr<ParamSubscriptionT> parameter_subscription_;
 
   // Callback for parameter updates
-  void on_parameter_event(const rcl_interfaces::msg::ParameterEvent::SharedPtr event);
+  void on_parameter_event(std::shared_ptr<const rcl_interfaces::msg::ParameterEvent> event);
 
   // An enum to hold the parameter state
   enum UseSimTimeParameterState {UNSET, SET_TRUE, SET_FALSE};
@@ -163,7 +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
-  rosgraph_msgs::msg::Clock::SharedPtr last_msg_set_;
+  std::shared_ptr<const rosgraph_msgs::msg::Clock> last_msg_set_;
 
   // A lock to protect iterating the associated_clocks_ field.
   std::mutex clock_list_lock_;

rclcpp/include/rclcpp/timer.hpp

@@ -181,7 +181,7 @@ public:
     TRACEPOINT(
       rclcpp_callback_register,
       static_cast<const void *>(&callback_),
-      get_symbol(callback_));
+      tracetools::get_symbol(callback_));
   }
 
   /// Default destructor.

rclcpp/include/rclcpp/topic_statistics/subscription_topic_statistics.hpp

@@ -127,7 +127,7 @@ public:
   /**
    * This method acquires a lock to prevent race conditions to collectors list.
    */
-  virtual void publish_message()
+  virtual void publish_message_and_reset_measurements()
   {
     std::vector<MetricsMessage> msgs;
     rclcpp::Time window_end{get_current_nanoseconds_since_epoch()};
@@ -136,6 +136,7 @@ public:
       std::lock_guard<std::mutex> lock(mutex_);
       for (auto & collector : subscriber_statistics_collectors_) {
         const auto collected_stats = collector->GetStatisticsResults();
+        collector->ClearCurrentMeasurements();
 
         auto message = libstatistics_collector::collector::GenerateStatisticMessage(
           node_name_,

rclcpp/include/rclcpp/typesupport_helpers.hpp

@@ -0,0 +1,57 @@
+// Copyright 2018, Bosch Software Innovations GmbH.
+// Copyright 2021, Apex.AI 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__TYPESUPPORT_HELPERS_HPP_
+#define RCLCPP__TYPESUPPORT_HELPERS_HPP_
+
+#include <memory>
+#include <string>
+#include <tuple>
+
+#include "rcpputils/shared_library.hpp"
+#include "rosidl_runtime_cpp/message_type_support_decl.hpp"
+
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+/// Load the type support library for the given type.
+/**
+ * \param[in] type The topic type, e.g. "std_msgs/msg/String"
+ * \param[in] typesupport_identifier Type support identifier, typically "rosidl_typesupport_cpp"
+ * \return A shared library
+ */
+RCLCPP_PUBLIC
+std::shared_ptr<rcpputils::SharedLibrary>
+get_typesupport_library(const std::string & type, const std::string & typesupport_identifier);
+
+/// Extract the type support handle from the library.
+/**
+ * The library needs to match the topic type. The shared library must stay loaded for the lifetime of the result.
+ * \param[in] type The topic type, e.g. "std_msgs/msg/String"
+ * \param[in] typesupport_identifier Type support identifier, typically "rosidl_typesupport_cpp"
+ * \param[in] library The shared type support library
+ * \return A type support handle
+ */
+RCLCPP_PUBLIC
+const rosidl_message_type_support_t *
+get_typesupport_handle(
+  const std::string & type,
+  const std::string & typesupport_identifier,
+  rcpputils::SharedLibrary & library);
+
+}  // namespace rclcpp
+
+#endif  // RCLCPP__TYPESUPPORT_HELPERS_HPP_

rclcpp/include/rclcpp/utilities.hpp

@@ -143,21 +143,6 @@ RCLCPP_PUBLIC
 bool
 ok(rclcpp::Context::SharedPtr context = nullptr);
 
-/// Return true if init() has already been called for the given context.
-/**
- * If nullptr is given for the context, then the global context is used, i.e.
- * the context initialized by rclcpp::init().
- *
- * Deprecated, as it is no longer different from rcl_ok().
- *
- * \param[in] context Optional check for initialization of this Context.
- * \return true if the context is initialized, and false otherwise
- */
-[[deprecated("use the function ok() instead, which has the same usage.")]]
-RCLCPP_PUBLIC
-bool
-is_initialized(rclcpp::Context::SharedPtr context = nullptr);
-
 /// Shutdown rclcpp context, invalidating it for derived entities.
 /**
  * If nullptr is given for the context, then the global context is used, i.e.

rclcpp/include/rclcpp/waitable.hpp

@@ -16,6 +16,7 @@
 #define RCLCPP__WAITABLE_HPP_
 
 #include <atomic>
+#include <memory>
 
 #include "rclcpp/macros.hpp"
 #include "rclcpp/visibility_control.hpp"
@@ -125,8 +126,17 @@ public:
   bool
   is_ready(rcl_wait_set_t * wait_set) = 0;
 
-  /// Execute any entities of the Waitable that are ready.
+  /// Take the data so that it can be consumed with `execute`.
   /**
+   * NOTE: take_data is a partial fix to a larger design issue with the
+   * multithreaded executor. This method is likely to be removed when
+   * a more permanent fix is implemented. A longterm fix is currently
+   * being discussed here: https://github.com/ros2/rclcpp/pull/1276
+   *
+   * This method takes the data from the underlying data structure and
+   * writes it to the void shared pointer `data` that is passed into the
+   * method. The `data` can then be executed with the `execute` method.
+   *
    * Before calling this method, the Waitable should be added to a wait set,
    * waited on, and then updated.
    *
@@ -143,13 +153,41 @@ public:
    * // Update the Waitable
    * waitable.update(wait_set);
    * // Execute any entities of the Waitable that may be ready
-   * waitable.execute();
+   * std::shared_ptr<void> data = waitable.take_data();
+   * ```
+   */
+  RCLCPP_PUBLIC
+  virtual
+  std::shared_ptr<void>
+  take_data() = 0;
+
+  /// Execute data that is passed in.
+  /**
+   * Before calling this method, the Waitable should be added to a wait set,
+   * waited on, and then updated - and the `take_data` method should be
+   * called.
+   *
+   * Example usage:
+   *
+   * ```cpp
+   * // ... create a wait set and a Waitable
+   * // Add the Waitable to the wait set
+   * bool add_ret = waitable.add_to_wait_set(wait_set);
+   * // ... error handling
+   * // Wait
+   * rcl_ret_t wait_ret = rcl_wait(wait_set);
+   * // ... error handling
+   * // Update the Waitable
+   * waitable.update(wait_set);
+   * // Execute any entities of the Waitable that may be ready
+   * std::shared_ptr<void> data = waitable.take_data();
+   * waitable.execute(data);
    * ```
    */
   RCLCPP_PUBLIC
   virtual
   void
-  execute() = 0;
+  execute(std::shared_ptr<void> & data) = 0;
 
   /// Exchange the "in use by wait set" state for this timer.
   /**

rclcpp/package.xml

@@ -2,7 +2,7 @@
 <?xml-model href="http://download.ros.org/schema/package_format2.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
 <package format="2">
   <name>rclcpp</name>
-  <version>5.0.0</version>
+  <version>9.0.2</version>
   <description>The ROS client library in C++.</description>
   <maintainer email="ivanpauno@ekumenlabs.com">Ivan Paunovic</maintainer>
   <maintainer email="mabel@openrobotics.org">Mabel Zhang</maintainer>
@@ -12,12 +12,14 @@
 
   <buildtool_depend>ament_cmake_ros</buildtool_depend>
 
+  <build_depend>ament_index_cpp</build_depend>
   <build_depend>builtin_interfaces</build_depend>
   <build_depend>rcl_interfaces</build_depend>
   <build_depend>rosgraph_msgs</build_depend>
   <build_depend>rosidl_runtime_cpp</build_depend>
   <build_depend>rosidl_typesupport_c</build_depend>
   <build_depend>rosidl_typesupport_cpp</build_depend>
+  <build_export_depend>ament_index_cpp</build_export_depend>
   <build_export_depend>builtin_interfaces</build_export_depend>
   <build_export_depend>rcl_interfaces</build_export_depend>
   <build_export_depend>rosgraph_msgs</build_export_depend>
@@ -39,6 +41,7 @@
   <test_depend>ament_lint_auto</test_depend>
   <test_depend>ament_lint_common</test_depend>
   <test_depend>mimick_vendor</test_depend>
+  <test_depend>performance_test_fixture</test_depend>
   <test_depend>rmw</test_depend>
   <test_depend>rmw_implementation_cmake</test_depend>
   <test_depend>rosidl_default_generators</test_depend>

rclcpp/resource/logging.hpp.em

@@ -151,10 +151,9 @@ def get_rclcpp_suffix_from_features(features):
 @[ end if]@
       logger.get_name(), \
 @[ if 'stream' not in feature_combination]@
-      rclcpp::get_c_string(RCLCPP_FIRST_ARG(__VA_ARGS__, "")), \
-        RCLCPP_ALL_BUT_FIRST_ARGS(__VA_ARGS__,"")); \
+      __VA_ARGS__); \
 @[ else]@
-      "%s", rclcpp::get_c_string(ss.str())); \
+      "%s", ss.str().c_str()); \
 @[ end if]@
   } while (0)
 

rclcpp/src/rclcpp/clock.cpp

@@ -113,7 +113,7 @@ Clock::get_clock_mutex() noexcept
 
 void
 Clock::on_time_jump(
-  const struct rcl_time_jump_t * time_jump,
+  const rcl_time_jump_t * time_jump,
   bool before_jump,
   void * user_data)
 {

rclcpp/src/rclcpp/context.cpp

@@ -291,7 +291,7 @@ Context::get_domain_id() const
 }
 
 std::string
-Context::shutdown_reason()
+Context::shutdown_reason() const
 {
   std::lock_guard<std::recursive_mutex> lock(init_mutex_);
   return shutdown_reason_;
@@ -320,7 +320,6 @@ Context::shutdown(const std::string & reason)
   }
   // interrupt all blocking sleep_for() and all blocking executors or wait sets
   this->interrupt_all_sleep_for();
-  this->interrupt_all_wait_sets();
   // remove self from the global contexts
   weak_contexts_->remove_context(this);
   // shutdown logger
@@ -391,75 +390,6 @@ Context::interrupt_all_sleep_for()
   interrupt_condition_variable_.notify_all();
 }
 
-rcl_guard_condition_t *
-Context::get_interrupt_guard_condition(rcl_wait_set_t * wait_set)
-{
-  std::lock_guard<std::mutex> lock(interrupt_guard_cond_handles_mutex_);
-  auto kv = interrupt_guard_cond_handles_.find(wait_set);
-  if (kv != interrupt_guard_cond_handles_.end()) {
-    return &kv->second;
-  } else {
-    rcl_guard_condition_t handle = rcl_get_zero_initialized_guard_condition();
-    rcl_guard_condition_options_t options = rcl_guard_condition_get_default_options();
-    auto ret = rcl_guard_condition_init(&handle, this->get_rcl_context().get(), options);
-    if (RCL_RET_OK != ret) {
-      rclcpp::exceptions::throw_from_rcl_error(ret, "Couldn't initialize guard condition");
-    }
-    interrupt_guard_cond_handles_.emplace(wait_set, handle);
-    return &interrupt_guard_cond_handles_[wait_set];
-  }
-}
-
-void
-Context::release_interrupt_guard_condition(rcl_wait_set_t * wait_set)
-{
-  std::lock_guard<std::mutex> lock(interrupt_guard_cond_handles_mutex_);
-  auto kv = interrupt_guard_cond_handles_.find(wait_set);
-  if (kv != interrupt_guard_cond_handles_.end()) {
-    rcl_ret_t ret = rcl_guard_condition_fini(&kv->second);
-    if (RCL_RET_OK != ret) {
-      rclcpp::exceptions::throw_from_rcl_error(ret, "Failed to destroy sigint guard condition");
-    }
-    interrupt_guard_cond_handles_.erase(kv);
-  } else {
-    throw std::runtime_error("Tried to release sigint guard condition for nonexistent wait set");
-  }
-}
-
-void
-Context::release_interrupt_guard_condition(
-  rcl_wait_set_t * wait_set,
-  const std::nothrow_t &) noexcept
-{
-  try {
-    this->release_interrupt_guard_condition(wait_set);
-  } catch (const std::exception & exc) {
-    RCLCPP_ERROR(
-      rclcpp::get_logger("rclcpp"),
-      "caught %s exception when releasing interrupt guard condition: %s",
-      rmw::impl::cpp::demangle(exc).c_str(), exc.what());
-  } catch (...) {
-    RCLCPP_ERROR(
-      rclcpp::get_logger("rclcpp"),
-      "caught unknown exception when releasing interrupt guard condition");
-  }
-}
-
-void
-Context::interrupt_all_wait_sets()
-{
-  std::lock_guard<std::mutex> lock(interrupt_guard_cond_handles_mutex_);
-  for (auto & kv : interrupt_guard_cond_handles_) {
-    rcl_ret_t status = rcl_trigger_guard_condition(&(kv.second));
-    if (status != RCL_RET_OK) {
-      RCUTILS_LOG_ERROR_NAMED(
-        "rclcpp",
-        "failed to trigger guard condition in Context::interrupt_all_wait_sets(): %s",
-        rcl_get_error_string().str);
-    }
-  }
-}
-
 void
 Context::clean_up()
 {

rclcpp/src/rclcpp/detail/mutex_two_priorities.cpp

@@ -0,0 +1,104 @@
+// Copyright 2021 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "rclcpp/detail/mutex_two_priorities.hpp"
+
+#include <mutex>
+
+namespace rclcpp
+{
+namespace detail
+{
+
+using LowPriorityLockable = MutexTwoPriorities::LowPriorityLockable;
+using HighPriorityLockable = MutexTwoPriorities::HighPriorityLockable;
+
+HighPriorityLockable::HighPriorityLockable(MutexTwoPriorities & parent)
+: parent_(parent)
+{}
+
+void
+HighPriorityLockable::lock()
+{
+  std::unique_lock<std::mutex> guard{parent_.cv_mutex_};
+  if (parent_.data_taken_) {
+    ++parent_.hp_waiting_count_;
+    while (parent_.data_taken_) {
+      parent_.hp_cv_.wait(guard);
+    }
+    --parent_.hp_waiting_count_;
+  }
+  parent_.data_taken_ = true;
+}
+
+void
+HighPriorityLockable::unlock()
+{
+  bool notify_lp{false};
+  {
+    std::lock_guard<std::mutex> guard{parent_.cv_mutex_};
+    parent_.data_taken_ = false;
+    notify_lp = 0u == parent_.hp_waiting_count_;
+  }
+  if (notify_lp) {
+    parent_.lp_cv_.notify_one();
+  } else {
+    parent_.hp_cv_.notify_one();
+  }
+}
+
+LowPriorityLockable::LowPriorityLockable(MutexTwoPriorities & parent)
+: parent_(parent)
+{}
+
+void
+LowPriorityLockable::lock()
+{
+  std::unique_lock<std::mutex> guard{parent_.cv_mutex_};
+  while (parent_.data_taken_ || parent_.hp_waiting_count_) {
+    parent_.lp_cv_.wait(guard);
+  }
+  parent_.data_taken_ = true;
+}
+
+void
+LowPriorityLockable::unlock()
+{
+  bool notify_lp{false};
+  {
+    std::lock_guard<std::mutex> guard{parent_.cv_mutex_};
+    parent_.data_taken_ = false;
+    notify_lp = 0u == parent_.hp_waiting_count_;
+  }
+  if (notify_lp) {
+    parent_.lp_cv_.notify_one();
+  } else {
+    parent_.hp_cv_.notify_one();
+  }
+}
+
+HighPriorityLockable
+MutexTwoPriorities::get_high_priority_lockable()
+{
+  return HighPriorityLockable{*this};
+}
+
+LowPriorityLockable
+MutexTwoPriorities::get_low_priority_lockable()
+{
+  return LowPriorityLockable{*this};
+}
+
+}  // namespace detail
+}  // namespace rclcpp

rclcpp/src/rclcpp/detail/resolve_parameter_overrides.cpp

@@ -0,0 +1,77 @@
+// Copyright 2021 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "./resolve_parameter_overrides.hpp"
+
+#include <string>
+#include <map>
+#include <vector>
+
+#include "rcl_yaml_param_parser/parser.h"
+
+#include "rclcpp/scope_exit.hpp"
+#include "rclcpp/parameter_map.hpp"
+
+std::map<std::string, rclcpp::ParameterValue>
+rclcpp::detail::resolve_parameter_overrides(
+  const std::string & node_fqn,
+  const std::vector<rclcpp::Parameter> & parameter_overrides,
+  const rcl_arguments_t * local_args,
+  const rcl_arguments_t * global_args)
+{
+  std::map<std::string, rclcpp::ParameterValue> result;
+
+  // global before local so that local overwrites global
+  std::array<const rcl_arguments_t *, 2> argument_sources = {global_args, local_args};
+
+  // Get fully qualified node name post-remapping to use to find node's params in yaml files
+
+  for (const rcl_arguments_t * source : argument_sources) {
+    if (!source) {
+      continue;
+    }
+    rcl_params_t * params = NULL;
+    rcl_ret_t ret = rcl_arguments_get_param_overrides(source, &params);
+    if (RCL_RET_OK != ret) {
+      rclcpp::exceptions::throw_from_rcl_error(ret);
+    }
+    if (params) {
+      auto cleanup_params = make_scope_exit(
+        [params]() {
+          rcl_yaml_node_struct_fini(params);
+        });
+      rclcpp::ParameterMap initial_map = rclcpp::parameter_map_from(params);
+
+      // 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());
+          }
+        }
+      }
+    }
+  }
+
+  // parameter overrides passed to constructor will overwrite overrides from yaml file sources
+  for (auto & param : parameter_overrides) {
+    result[param.get_name()] =
+      rclcpp::ParameterValue(param.get_value_message());
+  }
+  return result;
+}

rclcpp/src/rclcpp/detail/resolve_parameter_overrides.hpp

@@ -0,0 +1,44 @@
+// Copyright 2021 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__RESOLVE_PARAMETER_OVERRIDES_HPP_
+#define RCLCPP__DETAIL__RESOLVE_PARAMETER_OVERRIDES_HPP_
+
+#include <string>
+#include <map>
+#include <vector>
+
+#include "rcl/arguments.h"
+
+#include "rclcpp/parameter.hpp"
+#include "rclcpp/parameter_value.hpp"
+#include "rclcpp/visibility_control.hpp"
+
+namespace rclcpp
+{
+namespace detail
+{
+/// \internal Get the parameter overrides from the arguments.
+RCLCPP_LOCAL
+std::map<std::string, rclcpp::ParameterValue>
+resolve_parameter_overrides(
+  const std::string & node_name,
+  const std::vector<rclcpp::Parameter> & parameter_overrides,
+  const rcl_arguments_t * local_args,
+  const rcl_arguments_t * global_args);
+
+}  // namespace detail
+}  // namespace rclcpp
+
+#endif  // RCLCPP__DETAIL__RESOLVE_PARAMETER_OVERRIDES_HPP_

rclcpp/src/rclcpp/duration.cpp

@@ -37,7 +37,7 @@ Duration::Duration(int32_t seconds, uint32_t nanoseconds)
   rcl_duration_.nanoseconds += nanoseconds;
 }
 
-Duration::Duration(int64_t nanoseconds)
+Duration::Duration(rcl_duration_value_t nanoseconds)
 {
   rcl_duration_.nanoseconds = nanoseconds;
 }
@@ -67,13 +67,27 @@ Duration::operator builtin_interfaces::msg::Duration() const
 {
   builtin_interfaces::msg::Duration msg_duration;
   constexpr rcl_duration_value_t kDivisor = RCL_S_TO_NS(1);
+  constexpr int32_t max_s = std::numeric_limits<int32_t>::max();
+  constexpr int32_t min_s = std::numeric_limits<int32_t>::min();
+  constexpr uint32_t max_ns = std::numeric_limits<uint32_t>::max();
   const auto result = std::div(rcl_duration_.nanoseconds, kDivisor);
   if (result.rem >= 0) {
-    msg_duration.sec = static_cast<std::int32_t>(result.quot);
-    msg_duration.nanosec = static_cast<std::uint32_t>(result.rem);
+    // saturate if we will overflow
+    if (result.quot > max_s) {
+      msg_duration.sec = max_s;
+      msg_duration.nanosec = max_ns;
+    } else {
+      msg_duration.sec = static_cast<int32_t>(result.quot);
+      msg_duration.nanosec = static_cast<uint32_t>(result.rem);
+    }
   } else {
-    msg_duration.sec = static_cast<std::int32_t>(result.quot - 1);
-    msg_duration.nanosec = static_cast<std::uint32_t>(kDivisor + result.rem);
+    if (result.quot <= min_s) {
+      msg_duration.sec = min_s;
+      msg_duration.nanosec = 0u;
+    } else {
+      msg_duration.sec = static_cast<int32_t>(result.quot - 1);
+      msg_duration.nanosec = static_cast<uint32_t>(kDivisor + result.rem);
+    }
   }
   return msg_duration;
 }
@@ -148,7 +162,7 @@ Duration::operator+(const rclcpp::Duration & rhs) const
     this->rcl_duration_.nanoseconds,
     rhs.rcl_duration_.nanoseconds,
     std::numeric_limits<rcl_duration_value_t>::max());
-  return Duration(
+  return Duration::from_nanoseconds(
     rcl_duration_.nanoseconds + rhs.rcl_duration_.nanoseconds);
 }
 
@@ -177,7 +191,7 @@ Duration::operator-(const rclcpp::Duration & rhs) const
     rhs.rcl_duration_.nanoseconds,
     std::numeric_limits<rcl_duration_value_t>::max());
 
-  return Duration(
+  return Duration::from_nanoseconds(
     rcl_duration_.nanoseconds - rhs.rcl_duration_.nanoseconds);
 }
 
@@ -208,7 +222,7 @@ Duration::operator*(double scale) const
     scale,
     std::numeric_limits<rcl_duration_value_t>::max());
   long double scale_ld = static_cast<long double>(scale);
-  return Duration(
+  return Duration::from_nanoseconds(
     static_cast<rcl_duration_value_t>(
       static_cast<long double>(rcl_duration_.nanoseconds) * scale_ld));
 }
@@ -238,18 +252,52 @@ Duration::to_rmw_time() const
     throw std::runtime_error("rmw_time_t cannot be negative");
   }
 
-  // reuse conversion logic from msg creation
-  builtin_interfaces::msg::Duration msg = *this;
+  // Purposefully avoid creating from builtin_interfaces::msg::Duration
+  // to avoid possible overflow converting from int64_t to int32_t, then back to uint64_t
   rmw_time_t result;
-  result.sec = static_cast<uint64_t>(msg.sec);
-  result.nsec = static_cast<uint64_t>(msg.nanosec);
+  constexpr rcl_duration_value_t kDivisor = RCL_S_TO_NS(1);
+  const auto div_result = std::div(rcl_duration_.nanoseconds, kDivisor);
+  result.sec = static_cast<uint64_t>(div_result.quot);
+  result.nsec = static_cast<uint64_t>(div_result.rem);
+
   return result;
 }
 
+Duration
+Duration::from_rmw_time(rmw_time_t duration)
+{
+  Duration ret;
+  constexpr rcl_duration_value_t limit_ns = std::numeric_limits<rcl_duration_value_t>::max();
+  constexpr rcl_duration_value_t limit_sec = RCL_NS_TO_S(limit_ns);
+  if (duration.sec > limit_sec || duration.nsec > limit_ns) {
+    // saturate if will overflow
+    ret.rcl_duration_.nanoseconds = limit_ns;
+    return ret;
+  }
+  uint64_t total_ns = RCL_S_TO_NS(duration.sec) + duration.nsec;
+  if (total_ns > limit_ns) {
+    // saturate if will overflow
+    ret.rcl_duration_.nanoseconds = limit_ns;
+    return ret;
+  }
+  ret.rcl_duration_.nanoseconds = static_cast<rcl_duration_value_t>(total_ns);
+  return ret;
+}
+
 Duration
 Duration::from_seconds(double seconds)
 {
-  return Duration(static_cast<int64_t>(RCL_S_TO_NS(seconds)));
+  Duration ret;
+  ret.rcl_duration_.nanoseconds = static_cast<int64_t>(RCL_S_TO_NS(seconds));
+  return ret;
+}
+
+Duration
+Duration::from_nanoseconds(rcl_duration_value_t nanoseconds)
+{
+  Duration ret;
+  ret.rcl_duration_.nanoseconds = nanoseconds;
+  return ret;
 }
 
 }  // namespace rclcpp

rclcpp/src/rclcpp/executor.cpp

@@ -25,6 +25,8 @@
 
 #include "rclcpp/exceptions.hpp"
 #include "rclcpp/executor.hpp"
+#include "rclcpp/guard_condition.hpp"
+#include "rclcpp/memory_strategy.hpp"
 #include "rclcpp/node.hpp"
 #include "rclcpp/scope_exit.hpp"
 #include "rclcpp/utilities.hpp"
@@ -41,28 +43,35 @@ using rclcpp::FutureReturnCode;
 
 Executor::Executor(const rclcpp::ExecutorOptions & options)
 : spinning(false),
+  shutdown_guard_condition_(std::make_shared<rclcpp::GuardCondition>(options.context)),
   memory_strategy_(options.memory_strategy)
 {
+  // Store the context for later use.
+  context_ = options.context;
+
   rcl_guard_condition_options_t guard_condition_options = rcl_guard_condition_get_default_options();
   rcl_ret_t ret = rcl_guard_condition_init(
-    &interrupt_guard_condition_, options.context->get_rcl_context().get(), guard_condition_options);
+    &interrupt_guard_condition_, context_->get_rcl_context().get(), guard_condition_options);
   if (RCL_RET_OK != ret) {
     throw_from_rcl_error(ret, "Failed to create interrupt guard condition in Executor constructor");
   }
 
+  context_->on_shutdown(
+    [weak_gc = std::weak_ptr<rclcpp::GuardCondition>{shutdown_guard_condition_}]() {
+      auto strong_gc = weak_gc.lock();
+      if (strong_gc) {
+        strong_gc->trigger();
+      }
+    });
+
   // The number of guard conditions is always at least 2: 1 for the ctrl-c guard cond,
   // and one for the executor's guard cond (interrupt_guard_condition_)
-
-  // Put the global ctrl-c guard condition in
-  memory_strategy_->add_guard_condition(options.context->get_interrupt_guard_condition(&wait_set_));
+  memory_strategy_->add_guard_condition(&shutdown_guard_condition_->get_rcl_guard_condition());
 
   // Put the executor's guard condition in
   memory_strategy_->add_guard_condition(&interrupt_guard_condition_);
   rcl_allocator_t allocator = memory_strategy_->get_allocator();
 
-  // Store the context for later use.
-  context_ = options.context;
-
   ret = rcl_wait_set_init(
     &wait_set_,
     0, 2, 0, 0, 0, 0,
@@ -128,14 +137,14 @@ Executor::~Executor()
     rcl_reset_error();
   }
   // Remove and release the sigint guard condition
-  memory_strategy_->remove_guard_condition(context_->get_interrupt_guard_condition(&wait_set_));
-  context_->release_interrupt_guard_condition(&wait_set_, std::nothrow);
+  memory_strategy_->remove_guard_condition(&shutdown_guard_condition_->get_rcl_guard_condition());
 }
 
 std::vector<rclcpp::CallbackGroup::WeakPtr>
 Executor::get_all_callback_groups()
 {
   std::vector<rclcpp::CallbackGroup::WeakPtr> groups;
+  std::lock_guard<std::mutex> guard{mutex_};
   for (const auto & group_node_ptr : weak_groups_associated_with_executor_to_nodes_) {
     groups.push_back(group_node_ptr.first);
   }
@@ -149,6 +158,7 @@ std::vector<rclcpp::CallbackGroup::WeakPtr>
 Executor::get_manually_added_callback_groups()
 {
   std::vector<rclcpp::CallbackGroup::WeakPtr> groups;
+  std::lock_guard<std::mutex> guard{mutex_};
   for (auto const & group_node_ptr : weak_groups_associated_with_executor_to_nodes_) {
     groups.push_back(group_node_ptr.first);
   }
@@ -159,6 +169,7 @@ std::vector<rclcpp::CallbackGroup::WeakPtr>
 Executor::get_automatically_added_callback_groups_from_nodes()
 {
   std::vector<rclcpp::CallbackGroup::WeakPtr> groups;
+  std::lock_guard<std::mutex> guard{mutex_};
   for (auto const & group_node_ptr : weak_groups_to_nodes_associated_with_executor_) {
     groups.push_back(group_node_ptr.first);
   }
@@ -195,7 +206,7 @@ void
 Executor::add_callback_group_to_map(
   rclcpp::CallbackGroup::SharedPtr group_ptr,
   rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-  WeakCallbackGroupsToNodesMap & weak_groups_to_nodes,
+  rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap & weak_groups_to_nodes,
   bool notify)
 {
   // If the callback_group already has an executor
@@ -225,7 +236,6 @@ Executor::add_callback_group_to_map(
       }
     }
     // Add the node's notify condition to the guard condition handles
-    std::unique_lock<std::mutex> lock(memory_strategy_mutex_);
     memory_strategy_->add_guard_condition(node_ptr->get_notify_guard_condition());
   }
 }
@@ -236,6 +246,7 @@ Executor::add_callback_group(
   rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
   bool notify)
 {
+  std::lock_guard<std::mutex> guard{mutex_};
   this->add_callback_group_to_map(
     group_ptr,
     node_ptr,
@@ -251,6 +262,7 @@ Executor::add_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_pt
   if (has_executor.exchange(true)) {
     throw std::runtime_error("Node has already been added to an executor.");
   }
+  std::lock_guard<std::mutex> guard{mutex_};
   for (auto & weak_group : node_ptr->get_callback_groups()) {
     auto group_ptr = weak_group.lock();
     if (group_ptr != nullptr && !group_ptr->get_associated_with_executor_atomic().load() &&
@@ -269,7 +281,7 @@ Executor::add_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_pt
 void
 Executor::remove_callback_group_from_map(
   rclcpp::CallbackGroup::SharedPtr group_ptr,
-  WeakCallbackGroupsToNodesMap & weak_groups_to_nodes,
+  rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap & weak_groups_to_nodes,
   bool notify)
 {
   rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr;
@@ -299,7 +311,6 @@ Executor::remove_callback_group_from_map(
         throw_from_rcl_error(ret, "Failed to trigger guard condition on callback group remove");
       }
     }
-    std::unique_lock<std::mutex> lock(memory_strategy_mutex_);
     memory_strategy_->remove_guard_condition(node_ptr->get_notify_guard_condition());
   }
 }
@@ -309,6 +320,7 @@ Executor::remove_callback_group(
   rclcpp::CallbackGroup::SharedPtr group_ptr,
   bool notify)
 {
+  std::lock_guard<std::mutex> guard{mutex_};
   this->remove_callback_group_from_map(
     group_ptr,
     weak_groups_associated_with_executor_to_nodes_,
@@ -328,6 +340,7 @@ Executor::remove_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node
     throw std::runtime_error("Node needs to be associated with an executor.");
   }
 
+  std::lock_guard<std::mutex> guard{mutex_};
   bool found_node = false;
   auto node_it = weak_nodes_.begin();
   while (node_it != weak_nodes_.end()) {
@@ -342,27 +355,24 @@ Executor::remove_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node
   if (!found_node) {
     throw std::runtime_error("Node needs to be associated with this executor.");
   }
-  std::vector<rclcpp::CallbackGroup::SharedPtr> found_group_ptrs;
-  std::for_each(
-    weak_groups_to_nodes_associated_with_executor_.begin(),
-    weak_groups_to_nodes_associated_with_executor_.end(),
-    [&found_group_ptrs, node_ptr](std::pair<rclcpp::CallbackGroup::WeakPtr,
-    rclcpp::node_interfaces::NodeBaseInterface::WeakPtr> key_value_pair) {
-      auto weak_node_ptr = key_value_pair.second;
-      auto shared_node_ptr = weak_node_ptr.lock();
-      auto group_ptr = key_value_pair.first.lock();
-      if (shared_node_ptr == node_ptr) {
-        found_group_ptrs.push_back(group_ptr);
-      }
-    });
-  std::for_each(
-    found_group_ptrs.begin(), found_group_ptrs.end(), [this, notify]
-      (rclcpp::CallbackGroup::SharedPtr group_ptr) {
+
+  for (auto it = weak_groups_to_nodes_associated_with_executor_.begin();
+    it != weak_groups_to_nodes_associated_with_executor_.end(); )
+  {
+    auto weak_node_ptr = it->second;
+    auto shared_node_ptr = weak_node_ptr.lock();
+    auto group_ptr = it->first.lock();
+
+    // Increment iterator before removing in case it's invalidated
+    it++;
+    if (shared_node_ptr == node_ptr) {
       remove_callback_group_from_map(
         group_ptr,
         weak_groups_to_nodes_associated_with_executor_,
         notify);
-    });
+    }
+  }
+
   std::atomic_bool & has_executor = node_ptr->get_associated_with_executor_atomic();
   has_executor.store(false);
 }
@@ -484,6 +494,7 @@ Executor::set_memory_strategy(rclcpp::memory_strategy::MemoryStrategy::SharedPtr
   if (memory_strategy == nullptr) {
     throw std::runtime_error("Received NULL memory strategy in executor.");
   }
+  std::lock_guard<std::mutex> guard{mutex_};
   memory_strategy_ = memory_strategy;
 }
 
@@ -506,7 +517,7 @@ Executor::execute_any_executable(AnyExecutable & any_exec)
     execute_client(any_exec.client);
   }
   if (any_exec.waitable) {
-    any_exec.waitable->execute();
+    any_exec.waitable->execute(any_exec.data);
   }
   // Reset the callback_group, regardless of type
   any_exec.callback_group->can_be_taken_from().store(true);
@@ -599,16 +610,18 @@ Executor::execute_subscription(rclcpp::SubscriptionBase::SharedPtr subscription)
         return true;
       },
       [&]() {subscription->handle_loaned_message(loaned_msg, message_info);});
-    rcl_ret_t ret = rcl_return_loaned_message_from_subscription(
-      subscription->get_subscription_handle().get(),
-      loaned_msg);
-    if (RCL_RET_OK != ret) {
-      RCLCPP_ERROR(
-        rclcpp::get_logger("rclcpp"),
-        "rcl_return_loaned_message_from_subscription() failed for subscription on topic '%s': %s",
-        subscription->get_topic_name(), rcl_get_error_string().str);
+    if (nullptr != loaned_msg) {
+      rcl_ret_t ret = rcl_return_loaned_message_from_subscription(
+        subscription->get_subscription_handle().get(),
+        loaned_msg);
+      if (RCL_RET_OK != ret) {
+        RCLCPP_ERROR(
+          rclcpp::get_logger("rclcpp"),
+          "rcl_return_loaned_message_from_subscription() failed for subscription on topic '%s': %s",
+          subscription->get_topic_name(), rcl_get_error_string().str);
+      }
+      loaned_msg = nullptr;
     }
-    loaned_msg = nullptr;
   } else {
     // This case is taking a copy of the message data from the middleware via
     // inter-process communication.
@@ -657,7 +670,7 @@ void
 Executor::wait_for_work(std::chrono::nanoseconds timeout)
 {
   {
-    std::unique_lock<std::mutex> lock(memory_strategy_mutex_);
+    std::lock_guard<std::mutex> guard(mutex_);
 
     // Check weak_nodes_ to find any callback group that is not owned
     // by an executor and add it to the list of callbackgroups for
@@ -678,8 +691,11 @@ Executor::wait_for_work(std::chrono::nanoseconds timeout)
         if (weak_group_ptr.expired() || weak_node_ptr.expired()) {
           invalid_group_ptrs.push_back(weak_group_ptr);
           auto node_guard_pair = weak_nodes_to_guard_conditions_.find(weak_node_ptr);
-          weak_nodes_to_guard_conditions_.erase(weak_node_ptr);
-          memory_strategy_->remove_guard_condition(node_guard_pair->second);
+          if (node_guard_pair != weak_nodes_to_guard_conditions_.end()) {
+            auto guard_condition = node_guard_pair->second;
+            weak_nodes_to_guard_conditions_.erase(weak_node_ptr);
+            memory_strategy_->remove_guard_condition(guard_condition);
+          }
         }
       }
       std::for_each(
@@ -733,12 +749,14 @@ Executor::wait_for_work(std::chrono::nanoseconds timeout)
 
   // check the null handles in the wait set and remove them from the handles in memory strategy
   // for callback-based entities
+  std::lock_guard<std::mutex> guard(mutex_);
   memory_strategy_->remove_null_handles(&wait_set_);
 }
 
 rclcpp::node_interfaces::NodeBaseInterface::SharedPtr
 Executor::get_node_by_group(
-  WeakCallbackGroupsToNodesMap weak_groups_to_nodes,
+  const rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap &
+  weak_groups_to_nodes,
   rclcpp::CallbackGroup::SharedPtr group)
 {
   if (!group) {
@@ -756,6 +774,7 @@ Executor::get_node_by_group(
 rclcpp::CallbackGroup::SharedPtr
 Executor::get_group_by_timer(rclcpp::TimerBase::SharedPtr timer)
 {
+  std::lock_guard<std::mutex> guard{mutex_};
   for (const auto & pair : weak_groups_associated_with_executor_to_nodes_) {
     auto group = pair.first.lock();
     if (!group) {
@@ -796,9 +815,11 @@ Executor::get_next_ready_executable(AnyExecutable & any_executable)
 bool
 Executor::get_next_ready_executable_from_map(
   AnyExecutable & any_executable,
-  WeakCallbackGroupsToNodesMap weak_groups_to_nodes)
+  const rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap &
+  weak_groups_to_nodes)
 {
   bool success = false;
+  std::lock_guard<std::mutex> guard{mutex_};
   // Check the timers to see if there are any that are ready
   memory_strategy_->get_next_timer(any_executable, weak_groups_to_nodes);
   if (any_executable.timer) {
@@ -829,6 +850,7 @@ Executor::get_next_ready_executable_from_map(
     // Check the waitables to see if there are any that are ready
     memory_strategy_->get_next_waitable(any_executable, weak_groups_to_nodes);
     if (any_executable.waitable) {
+      any_executable.data = any_executable.waitable->take_data();
       success = true;
     }
   }
@@ -884,7 +906,8 @@ Executor::get_next_executable(AnyExecutable & any_executable, std::chrono::nanos
 bool
 Executor::has_node(
   const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-  WeakCallbackGroupsToNodesMap weak_groups_to_nodes) const
+  const rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap &
+  weak_groups_to_nodes) const
 {
   return std::find_if(
     weak_groups_to_nodes.begin(),

rclcpp/src/rclcpp/executors/multi_threaded_executor.cpp

@@ -22,6 +22,7 @@
 #include "rclcpp/utilities.hpp"
 #include "rclcpp/scope_exit.hpp"
 
+using rclcpp::detail::MutexTwoPriorities;
 using rclcpp::executors::MultiThreadedExecutor;
 
 MultiThreadedExecutor::MultiThreadedExecutor(
@@ -51,7 +52,8 @@ MultiThreadedExecutor::spin()
   std::vector<std::thread> threads;
   size_t thread_id = 0;
   {
-    std::lock_guard<std::mutex> wait_lock(wait_mutex_);
+    auto low_priority_wait_mutex = wait_mutex_.get_low_priority_lockable();
+    std::lock_guard<MutexTwoPriorities::LowPriorityLockable> wait_lock(low_priority_wait_mutex);
     for (; thread_id < number_of_threads_ - 1; ++thread_id) {
       auto func = std::bind(&MultiThreadedExecutor::run, this, thread_id);
       threads.emplace_back(func);
@@ -76,7 +78,8 @@ MultiThreadedExecutor::run(size_t)
   while (rclcpp::ok(this->context_) && spinning.load()) {
     rclcpp::AnyExecutable any_exec;
     {
-      std::lock_guard<std::mutex> wait_lock(wait_mutex_);
+      auto low_priority_wait_mutex = wait_mutex_.get_low_priority_lockable();
+      std::lock_guard<MutexTwoPriorities::LowPriorityLockable> wait_lock(low_priority_wait_mutex);
       if (!rclcpp::ok(this->context_) || !spinning.load()) {
         return;
       }
@@ -103,7 +106,8 @@ MultiThreadedExecutor::run(size_t)
     execute_any_executable(any_exec);
 
     if (any_exec.timer) {
-      std::lock_guard<std::mutex> wait_lock(wait_mutex_);
+      auto high_priority_wait_mutex = wait_mutex_.get_high_priority_lockable();
+      std::lock_guard<MutexTwoPriorities::HighPriorityLockable> wait_lock(high_priority_wait_mutex);
       auto it = scheduled_timers_.find(any_exec.timer);
       if (it != scheduled_timers_.end()) {
         scheduled_timers_.erase(it);

rclcpp/src/rclcpp/executors/static_executor_entities_collector.cpp

@@ -76,8 +76,13 @@ StaticExecutorEntitiesCollector::init(
 
   // Add executor's guard condition
   memory_strategy_->add_guard_condition(executor_guard_condition);
+
   // Get memory strategy and executable list. Prepare wait_set_
-  execute();
+  std::shared_ptr<void> shared_ptr;
+  execute(shared_ptr);
+
+  // The entities collector is now initialized
+  initialized_ = true;
 }
 
 void
@@ -87,9 +92,16 @@ StaticExecutorEntitiesCollector::fini()
   exec_list_.clear();
 }
 
-void
-StaticExecutorEntitiesCollector::execute()
+std::shared_ptr<void>
+StaticExecutorEntitiesCollector::take_data()
 {
+  return nullptr;
+}
+
+void
+StaticExecutorEntitiesCollector::execute(std::shared_ptr<void> & data)
+{
+  (void) data;
   // Fill memory strategy with entities coming from weak_nodes_
   fill_memory_strategy();
   // Fill exec_list_ with entities coming from weak_nodes_ (same as memory strategy)
@@ -155,7 +167,8 @@ StaticExecutorEntitiesCollector::fill_executable_list()
 }
 void
 StaticExecutorEntitiesCollector::fill_executable_list_from_map(
-  const WeakCallbackGroupsToNodesMap & weak_groups_to_nodes)
+  const rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap &
+  weak_groups_to_nodes)
 {
   for (const auto & pair : weak_groups_to_nodes) {
     auto group = pair.first.lock();
@@ -297,7 +310,7 @@ bool
 StaticExecutorEntitiesCollector::add_callback_group(
   rclcpp::CallbackGroup::SharedPtr group_ptr,
   rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-  WeakCallbackGroupsToNodesMap & weak_groups_to_nodes)
+  rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap & weak_groups_to_nodes)
 {
   // If the callback_group already has an executor
   std::atomic_bool & has_executor = group_ptr->get_associated_with_executor_atomic();
@@ -314,8 +327,7 @@ StaticExecutorEntitiesCollector::add_callback_group(
     throw std::runtime_error("Callback group was already added to executor.");
   }
   if (is_new_node) {
-    rclcpp::node_interfaces::NodeBaseInterface::WeakPtr node_weak_ptr(node_ptr);
-    weak_nodes_to_guard_conditions_[node_weak_ptr] = node_ptr->get_notify_guard_condition();
+    weak_nodes_to_guard_conditions_[node_ptr] = node_ptr->get_notify_guard_condition();
     return true;
   }
   return false;
@@ -341,7 +353,7 @@ StaticExecutorEntitiesCollector::remove_callback_group(
 bool
 StaticExecutorEntitiesCollector::remove_callback_group_from_map(
   rclcpp::CallbackGroup::SharedPtr group_ptr,
-  WeakCallbackGroupsToNodesMap & weak_groups_to_nodes)
+  rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap & weak_groups_to_nodes)
 {
   rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr;
   rclcpp::CallbackGroup::WeakPtr weak_group_ptr = group_ptr;
@@ -437,7 +449,8 @@ StaticExecutorEntitiesCollector::is_ready(rcl_wait_set_t * p_wait_set)
 bool
 StaticExecutorEntitiesCollector::has_node(
   const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr,
-  const WeakCallbackGroupsToNodesMap & weak_groups_to_nodes) const
+  const rclcpp::memory_strategy::MemoryStrategy::WeakCallbackGroupsToNodesMap &
+  weak_groups_to_nodes) const
 {
   return std::find_if(
     weak_groups_to_nodes.begin(),

rclcpp/src/rclcpp/executors/static_single_threaded_executor.cpp

@@ -14,6 +14,7 @@
 
 #include "rclcpp/executors/static_single_threaded_executor.hpp"
 
+#include <chrono>
 #include <memory>
 #include <vector>
 
@@ -29,7 +30,12 @@ StaticSingleThreadedExecutor::StaticSingleThreadedExecutor(
   entities_collector_ = std::make_shared<StaticExecutorEntitiesCollector>();
 }
 
-StaticSingleThreadedExecutor::~StaticSingleThreadedExecutor() {}
+StaticSingleThreadedExecutor::~StaticSingleThreadedExecutor()
+{
+  if (entities_collector_->is_init()) {
+    entities_collector_->fini();
+  }
+}
 
 void
 StaticSingleThreadedExecutor::spin()
@@ -42,7 +48,6 @@ StaticSingleThreadedExecutor::spin()
   // Set memory_strategy_ and exec_list_ based on weak_nodes_
   // Prepare wait_set_ based on memory_strategy_
   entities_collector_->init(&wait_set_, memory_strategy_, &interrupt_guard_condition_);
-  RCLCPP_SCOPE_EXIT(entities_collector_->fini());
 
   while (rclcpp::ok(this->context_) && spinning.load()) {
     // Refresh wait set and wait for work
@@ -51,6 +56,79 @@ StaticSingleThreadedExecutor::spin()
   }
 }
 
+void
+StaticSingleThreadedExecutor::spin_some(std::chrono::nanoseconds max_duration)
+{
+  // In this context a 0 input max_duration means no duration limit
+  if (std::chrono::nanoseconds(0) == max_duration) {
+    max_duration = std::chrono::nanoseconds::max();
+  }
+
+  return this->spin_some_impl(max_duration, false);
+}
+
+void
+StaticSingleThreadedExecutor::spin_all(std::chrono::nanoseconds max_duration)
+{
+  if (max_duration <= std::chrono::nanoseconds(0)) {
+    throw std::invalid_argument("max_duration must be positive");
+  }
+  return this->spin_some_impl(max_duration, true);
+}
+
+void
+StaticSingleThreadedExecutor::spin_some_impl(std::chrono::nanoseconds max_duration, bool exhaustive)
+{
+  // Make sure the entities collector has been initialized
+  if (!entities_collector_->is_init()) {
+    entities_collector_->init(&wait_set_, memory_strategy_, &interrupt_guard_condition_);
+  }
+
+  auto start = std::chrono::steady_clock::now();
+  auto max_duration_not_elapsed = [max_duration, start]() {
+      if (std::chrono::nanoseconds(0) == max_duration) {
+        // told to spin forever if need be
+        return true;
+      } else if (std::chrono::steady_clock::now() - start < max_duration) {
+        // told to spin only for some maximum amount of time
+        return true;
+      }
+      // spun too long
+      return false;
+    };
+
+  if (spinning.exchange(true)) {
+    throw std::runtime_error("spin_some() called while already spinning");
+  }
+  RCLCPP_SCOPE_EXIT(this->spinning.store(false); );
+
+  while (rclcpp::ok(context_) && spinning.load() && max_duration_not_elapsed()) {
+    // Get executables that are ready now
+    entities_collector_->refresh_wait_set(std::chrono::milliseconds::zero());
+    // Execute ready executables
+    bool work_available = execute_ready_executables();
+    if (!work_available || !exhaustive) {
+      break;
+    }
+  }
+}
+
+void
+StaticSingleThreadedExecutor::spin_once_impl(std::chrono::nanoseconds timeout)
+{
+  // Make sure the entities collector has been initialized
+  if (!entities_collector_->is_init()) {
+    entities_collector_->init(&wait_set_, memory_strategy_, &interrupt_guard_condition_);
+  }
+
+  if (rclcpp::ok(context_) && spinning.load()) {
+    // Wait until we have a ready entity or timeout expired
+    entities_collector_->refresh_wait_set(timeout);
+    // Execute ready executables
+    execute_ready_executables(true);
+  }
+}
+
 void
 StaticSingleThreadedExecutor::add_callback_group(
   rclcpp::CallbackGroup::SharedPtr group_ptr,
@@ -138,14 +216,20 @@ StaticSingleThreadedExecutor::remove_node(std::shared_ptr<rclcpp::Node> node_ptr
   this->remove_node(node_ptr->get_node_base_interface(), notify);
 }
 
-void
-StaticSingleThreadedExecutor::execute_ready_executables()
+bool
+StaticSingleThreadedExecutor::execute_ready_executables(bool spin_once)
 {
+  bool any_ready_executable = false;
+
   // Execute all the ready subscriptions
   for (size_t i = 0; i < wait_set_.size_of_subscriptions; ++i) {
     if (i < entities_collector_->get_number_of_subscriptions()) {
       if (wait_set_.subscriptions[i]) {
         execute_subscription(entities_collector_->get_subscription(i));
+        if (spin_once) {
+          return true;
+        }
+        any_ready_executable = true;
       }
     }
   }
@@ -154,6 +238,10 @@ StaticSingleThreadedExecutor::execute_ready_executables()
     if (i < entities_collector_->get_number_of_timers()) {
       if (wait_set_.timers[i] && entities_collector_->get_timer(i)->is_ready()) {
         execute_timer(entities_collector_->get_timer(i));
+        if (spin_once) {
+          return true;
+        }
+        any_ready_executable = true;
       }
     }
   }
@@ -162,6 +250,10 @@ StaticSingleThreadedExecutor::execute_ready_executables()
     if (i < entities_collector_->get_number_of_services()) {
       if (wait_set_.services[i]) {
         execute_service(entities_collector_->get_service(i));
+        if (spin_once) {
+          return true;
+        }
+        any_ready_executable = true;
       }
     }
   }
@@ -170,13 +262,24 @@ StaticSingleThreadedExecutor::execute_ready_executables()
     if (i < entities_collector_->get_number_of_clients()) {
       if (wait_set_.clients[i]) {
         execute_client(entities_collector_->get_client(i));
+        if (spin_once) {
+          return true;
+        }
+        any_ready_executable = true;
       }
     }
   }
   // Execute all the ready waitables
   for (size_t i = 0; i < entities_collector_->get_number_of_waitables(); ++i) {
-    if (entities_collector_->get_waitable(i)->is_ready(&wait_set_)) {
-      entities_collector_->get_waitable(i)->execute();
+    auto waitable = entities_collector_->get_waitable(i);
+    if (waitable->is_ready(&wait_set_)) {
+      auto data = waitable->take_data();
+      waitable->execute(data);
+      if (spin_once) {
+        return true;
+      }
+      any_ready_executable = true;
     }
   }
+  return any_ready_executable;
 }

rclcpp/src/rclcpp/generic_publisher.cpp

@@ -0,0 +1,34 @@
+// Copyright 2018, Bosch Software Innovations GmbH.
+// Copyright 2021, Apex.AI Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "rclcpp/generic_publisher.hpp"
+
+#include <memory>
+#include <string>
+
+namespace rclcpp
+{
+
+void GenericPublisher::publish(const rclcpp::SerializedMessage & message)
+{
+  auto return_code = rcl_publish_serialized_message(
+    get_publisher_handle().get(), &message.get_rcl_serialized_message(), NULL);
+
+  if (return_code != RCL_RET_OK) {
+    rclcpp::exceptions::throw_from_rcl_error(return_code, "failed to publish serialized message");
+  }
+}
+
+}  // namespace rclcpp

rclcpp/src/rclcpp/generic_subscription.cpp

@@ -0,0 +1,67 @@
+// Copyright 2018, Bosch Software Innovations GmbH.
+// Copyright 2021, Apex.AI Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "rclcpp/generic_subscription.hpp"
+
+#include <memory>
+#include <string>
+
+#include "rcl/subscription.h"
+
+#include "rclcpp/exceptions.hpp"
+
+namespace rclcpp
+{
+
+std::shared_ptr<void> GenericSubscription::create_message()
+{
+  return create_serialized_message();
+}
+
+std::shared_ptr<rclcpp::SerializedMessage> GenericSubscription::create_serialized_message()
+{
+  return std::make_shared<rclcpp::SerializedMessage>(0);
+}
+
+void GenericSubscription::handle_message(
+  std::shared_ptr<void> & message, const rclcpp::MessageInfo & message_info)
+{
+  (void) message_info;
+  auto typed_message = std::static_pointer_cast<rclcpp::SerializedMessage>(message);
+  callback_(typed_message);
+}
+
+void GenericSubscription::handle_loaned_message(
+  void * message, const rclcpp::MessageInfo & message_info)
+{
+  (void) message;
+  (void) message_info;
+  throw rclcpp::exceptions::UnimplementedError(
+          "handle_loaned_message is not implemented for GenericSubscription");
+}
+
+void GenericSubscription::return_message(std::shared_ptr<void> & message)
+{
+  auto typed_message = std::static_pointer_cast<rclcpp::SerializedMessage>(message);
+  return_serialized_message(typed_message);
+}
+
+void GenericSubscription::return_serialized_message(
+  std::shared_ptr<rclcpp::SerializedMessage> & message)
+{
+  message.reset();
+}
+
+}  // namespace rclcpp

rclcpp/src/rclcpp/graph_listener.cpp

@@ -36,11 +36,11 @@ namespace rclcpp
 namespace graph_listener
 {
 
-GraphListener::GraphListener(std::shared_ptr<rclcpp::Context> parent_context)
-: parent_context_(parent_context),
+GraphListener::GraphListener(const std::shared_ptr<Context> & parent_context)
+: weak_parent_context_(parent_context),
+  rcl_parent_context_(parent_context->get_rcl_context()),
   is_started_(false),
-  is_shutdown_(false),
-  shutdown_guard_condition_(nullptr)
+  is_shutdown_(false)
 {
   // TODO(wjwwood): make a guard condition class in rclcpp so this can be tracked
   //   automatically with the rcl guard condition
@@ -48,13 +48,11 @@ GraphListener::GraphListener(std::shared_ptr<rclcpp::Context> parent_context)
   // guard condition is using it.
   rcl_ret_t ret = rcl_guard_condition_init(
     &interrupt_guard_condition_,
-    parent_context->get_rcl_context().get(),
+    rcl_parent_context_.get(),
     rcl_guard_condition_get_default_options());
   if (RCL_RET_OK != ret) {
     throw_from_rcl_error(ret, "failed to create interrupt guard condition");
   }
-
-  shutdown_guard_condition_ = parent_context->get_interrupt_guard_condition(&wait_set_);
 }
 
 GraphListener::~GraphListener()
@@ -62,6 +60,23 @@ GraphListener::~GraphListener()
   this->shutdown(std::nothrow);
 }
 
+void GraphListener::init_wait_set()
+{
+  rcl_ret_t ret = rcl_wait_set_init(
+    &wait_set_,
+    0,  // number_of_subscriptions
+    2,  // number_of_guard_conditions
+    0,  // number_of_timers
+    0,  // number_of_clients
+    0,  // number_of_services
+    0,  // number_of_events
+    rcl_parent_context_.get(),
+    rcl_get_default_allocator());
+  if (RCL_RET_OK != ret) {
+    throw_from_rcl_error(ret, "failed to initialize wait set");
+  }
+}
+
 void
 GraphListener::start_if_not_started()
 {
@@ -69,30 +84,13 @@ GraphListener::start_if_not_started()
   if (is_shutdown_.load()) {
     throw GraphListenerShutdownError();
   }
-  if (!is_started_) {
-    // Initialize the wait set before starting.
-    auto parent_context = parent_context_.lock();
-    if (!parent_context) {
-      throw std::runtime_error("parent context was destroyed");
-    }
-    rcl_ret_t ret = rcl_wait_set_init(
-      &wait_set_,
-      0,  // number_of_subscriptions
-      2,  // number_of_guard_conditions
-      0,  // number_of_timers
-      0,  // number_of_clients
-      0,  // number_of_services
-      0,  // number_of_events
-      parent_context->get_rcl_context().get(),
-      rcl_get_default_allocator());
-    if (RCL_RET_OK != ret) {
-      throw_from_rcl_error(ret, "failed to initialize wait set");
-    }
+  auto parent_context = weak_parent_context_.lock();
+  if (!is_started_ && parent_context) {
     // Register an on_shutdown hook to shtudown the graph listener.
     // This is important to ensure that the wait set is finalized before
     // destruction of static objects occurs.
     std::weak_ptr<GraphListener> weak_this = shared_from_this();
-    rclcpp::on_shutdown(
+    parent_context->on_shutdown(
       [weak_this]() {
         auto shared_this = weak_this.lock();
         if (shared_this) {
@@ -100,6 +98,8 @@ GraphListener::start_if_not_started()
           shared_this->shutdown(std::nothrow);
         }
       });
+    // Initialize the wait set before starting.
+    init_wait_set();
     // Start the listener thread.
     listener_thread_ = std::thread(&GraphListener::run, this);
     is_started_ = true;
@@ -144,14 +144,6 @@ GraphListener::run_loop()
     }
     // This lock is released when the loop continues or exits.
     std::lock_guard<std::mutex> nodes_lock(node_graph_interfaces_mutex_, std::adopt_lock);
-    // Ensure that the context doesn't go out of scope.
-    auto parent_context = parent_context_.lock();
-    if (!parent_context) {
-      // The parent context may be destroyed before this loop is stopped.
-      // In that case, the loop is broken and the function just returns silently.
-      return;
-    }
-
     // Resize the wait set if necessary.
     const size_t node_graph_interfaces_size = node_graph_interfaces_.size();
     // Add 2 for the interrupt and shutdown guard conditions
@@ -171,13 +163,7 @@ GraphListener::run_loop()
     if (RCL_RET_OK != ret) {
       throw_from_rcl_error(ret, "failed to add interrupt guard condition to wait set");
     }
-    // Put the shutdown guard condition in the wait set.
-    size_t shutdown_guard_condition_index = 0u;
-    ret = rcl_wait_set_add_guard_condition(
-      &wait_set_, shutdown_guard_condition_, &shutdown_guard_condition_index);
-    if (RCL_RET_OK != ret) {
-      throw_from_rcl_error(ret, "failed to add shutdown guard condition to wait set");
-    }
+
     // Put graph guard conditions for each node into the wait set.
     std::vector<size_t> graph_gc_indexes(node_graph_interfaces_size, 0u);
     for (size_t i = 0u; i < node_graph_interfaces_size; ++i) {
@@ -206,9 +192,6 @@ GraphListener::run_loop()
       throw_from_rcl_error(ret, "failed to wait on wait set");
     }
 
-    // Check to see if the shutdown guard condition has been triggered.
-    bool shutdown_guard_condition_triggered =
-      (shutdown_guard_condition_ == wait_set_.guard_conditions[shutdown_guard_condition_index]);
     // Notify nodes who's guard conditions are set (triggered).
     for (size_t i = 0u; i < node_graph_interfaces_size; ++i) {
       const auto node_ptr = node_graph_interfaces_[i];
@@ -219,7 +202,7 @@ GraphListener::run_loop()
       if (graph_gc == wait_set_.guard_conditions[graph_gc_indexes[i]]) {
         node_ptr->notify_graph_change();
       }
-      if (shutdown_guard_condition_triggered) {
+      if (is_shutdown_) {
         // If shutdown, then notify the node of this as well.
         node_ptr->notify_shutdown();
       }
@@ -351,7 +334,16 @@ GraphListener::remove_node(rclcpp::node_interfaces::NodeGraphInterface * node_gr
 }
 
 void
-GraphListener::__shutdown(bool should_throw)
+GraphListener::cleanup_wait_set()
+{
+  rcl_ret_t ret = rcl_wait_set_fini(&wait_set_);
+  if (RCL_RET_OK != ret) {
+    throw_from_rcl_error(ret, "failed to finalize wait set");
+  }
+}
+
+void
+GraphListener::__shutdown()
 {
   std::lock_guard<std::mutex> shutdown_lock(shutdown_mutex_);
   if (!is_shutdown_.exchange(true)) {
@@ -363,33 +355,8 @@ GraphListener::__shutdown(bool should_throw)
     if (RCL_RET_OK != ret) {
       throw_from_rcl_error(ret, "failed to finalize interrupt guard condition");
     }
-    if (shutdown_guard_condition_) {
-      auto parent_context_ptr = parent_context_.lock();
-      if (parent_context_ptr) {
-        if (should_throw) {
-          parent_context_ptr->release_interrupt_guard_condition(&wait_set_);
-        } else {
-          parent_context_ptr->release_interrupt_guard_condition(&wait_set_, std::nothrow);
-        }
-      } else {
-        ret = rcl_guard_condition_fini(shutdown_guard_condition_);
-        if (RCL_RET_OK != ret) {
-          if (should_throw) {
-            throw_from_rcl_error(ret, "failed to finalize shutdown guard condition");
-          } else {
-            RCLCPP_ERROR(
-              rclcpp::get_logger("rclcpp"),
-              "failed to finalize shutdown guard condition");
-          }
-        }
-      }
-      shutdown_guard_condition_ = nullptr;
-    }
     if (is_started_) {
-      ret = rcl_wait_set_fini(&wait_set_);
-      if (RCL_RET_OK != ret) {
-        throw_from_rcl_error(ret, "failed to finalize wait set");
-      }
+      cleanup_wait_set();
     }
   }
 }
@@ -397,14 +364,14 @@ GraphListener::__shutdown(bool should_throw)
 void
 GraphListener::shutdown()
 {
-  this->__shutdown(true);
+  this->__shutdown();
 }
 
 void
 GraphListener::shutdown(const std::nothrow_t &) noexcept
 {
   try {
-    this->__shutdown(false);
+    this->__shutdown();
   } catch (const std::exception & exc) {
     RCLCPP_ERROR(
       rclcpp::get_logger("rclcpp"),

rclcpp/src/rclcpp/intra_process_manager.cpp

@@ -157,7 +157,13 @@ IntraProcessManager::get_subscription_intra_process(uint64_t intra_process_subsc
   if (subscription_it == subscriptions_.end()) {
     return nullptr;
   } else {
-    return subscription_it->second.subscription;
+    auto subscription = subscription_it->second.subscription.lock();
+    if (subscription) {
+      return subscription;
+    } else {
+      subscriptions_.erase(subscription_it);
+      return nullptr;
+    }
   }
 }
 

rclcpp/src/rclcpp/logger.cpp

@@ -14,6 +14,8 @@
 
 #include <string>
 
+#include "rcl_logging_interface/rcl_logging_interface.h"
+
 #include "rclcpp/exceptions.hpp"
 #include "rclcpp/logger.hpp"
 #include "rclcpp/logging.hpp"
@@ -38,12 +40,28 @@ get_node_logger(const rcl_node_t * node)
   const char * logger_name = rcl_node_get_logger_name(node);
   if (nullptr == logger_name) {
     auto logger = rclcpp::get_logger("rclcpp");
-    RCLCPP_ERROR(logger, "failed to get logger name from node at address %p", node);
+    RCLCPP_ERROR(
+      logger, "failed to get logger name from node at address %p",
+      static_cast<void *>(const_cast<rcl_node_t *>(node)));
     return logger;
   }
   return rclcpp::get_logger(logger_name);
 }
 
+rcpputils::fs::path
+get_logging_directory()
+{
+  char * log_dir = NULL;
+  auto allocator = rcutils_get_default_allocator();
+  rcl_logging_ret_t ret = rcl_logging_get_logging_directory(allocator, &log_dir);
+  if (RCL_LOGGING_RET_OK != ret) {
+    rclcpp::exceptions::throw_from_rcl_error(ret);
+  }
+  std::string path{log_dir};
+  allocator.deallocate(log_dir, allocator.state);
+  return path;
+}
+
 void
 Logger::set_level(Level level)
 {

rclcpp/src/rclcpp/network_flow_endpoint.cpp

@@ -0,0 +1,84 @@
+// Copyright 2020 Ericsson AB
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <string>
+
+#include "rclcpp/network_flow_endpoint.hpp"
+
+namespace rclcpp
+{
+
+const std::string &
+NetworkFlowEndpoint::transport_protocol() const
+{
+  return transport_protocol_;
+}
+
+const std::string &
+NetworkFlowEndpoint::internet_protocol() const
+{
+  return internet_protocol_;
+}
+
+uint16_t NetworkFlowEndpoint::transport_port() const
+{
+  return transport_port_;
+}
+
+uint32_t NetworkFlowEndpoint::flow_label() const
+{
+  return flow_label_;
+}
+
+uint8_t NetworkFlowEndpoint::dscp() const
+{
+  return dscp_;
+}
+
+const std::string &
+NetworkFlowEndpoint::internet_address() const
+{
+  return internet_address_;
+}
+
+bool operator==(const NetworkFlowEndpoint & left, const NetworkFlowEndpoint & right)
+{
+  return left.transport_protocol_ == right.transport_protocol_ &&
+         left.internet_protocol_ == right.internet_protocol_ &&
+         left.transport_port_ == right.transport_port_ &&
+         left.flow_label_ == right.flow_label_ &&
+         left.dscp_ == right.dscp_ &&
+         left.internet_address_ == right.internet_address_;
+}
+
+bool operator!=(const NetworkFlowEndpoint & left, const NetworkFlowEndpoint & right)
+{
+  return !(left == right);
+}
+
+std::ostream & operator<<(std::ostream & os, const NetworkFlowEndpoint & network_flow_endpoint)
+{
+  // Stream out in JSON-like format
+  os << "{" <<
+    "\"transportProtocol\": \"" << network_flow_endpoint.transport_protocol_ << "\", " <<
+    "\"internetProtocol\": \"" << network_flow_endpoint.internet_protocol_ << "\", " <<
+    "\"transportPort\": \"" << network_flow_endpoint.transport_port_ << "\", " <<
+    "\"flowLabel\": \"" << std::to_string(network_flow_endpoint.flow_label_) << "\", " <<
+    "\"dscp\": \"" << std::to_string(network_flow_endpoint.dscp_) << "\", " <<
+    "\"internetAddress\": \"" << network_flow_endpoint.internet_address_ << "\"" <<
+    "}";
+  return os;
+}
+
+}  // namespace rclcpp

rclcpp/src/rclcpp/node.cpp

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #include <algorithm>
+#include <array>
 #include <limits>
 #include <map>
 #include <memory>
@@ -20,6 +21,9 @@
 #include <utility>
 #include <vector>
 
+#include "rcl/arguments.h"
+
+#include "rclcpp/detail/qos_parameters.hpp"
 #include "rclcpp/exceptions.hpp"
 #include "rclcpp/graph_listener.hpp"
 #include "rclcpp/node.hpp"
@@ -33,9 +37,12 @@
 #include "rclcpp/node_interfaces/node_timers.hpp"
 #include "rclcpp/node_interfaces/node_topics.hpp"
 #include "rclcpp/node_interfaces/node_waitables.hpp"
+#include "rclcpp/qos_overriding_options.hpp"
 
 #include "rmw/validate_namespace.h"
 
+#include "./detail/resolve_parameter_overrides.hpp"
+
 using rclcpp::Node;
 using rclcpp::NodeOptions;
 using rclcpp::exceptions::throw_from_rcl_error;
@@ -94,6 +101,45 @@ Node::Node(
 {
 }
 
+static
+rclcpp::QoS
+get_parameter_events_qos(
+  rclcpp::node_interfaces::NodeBaseInterface & node_base,
+  const rclcpp::NodeOptions & options)
+{
+  auto final_qos = options.parameter_event_qos();
+  const rcl_arguments_t * global_args = nullptr;
+  auto * rcl_options = options.get_rcl_node_options();
+  if (rcl_options->use_global_arguments) {
+    auto context_ptr = node_base.get_context()->get_rcl_context();
+    global_args = &(context_ptr->global_arguments);
+  }
+
+  auto parameter_overrides = rclcpp::detail::resolve_parameter_overrides(
+    node_base.get_fully_qualified_name(),
+    options.parameter_overrides(),
+    &rcl_options->arguments,
+    global_args);
+
+  auto final_topic_name = node_base.resolve_topic_or_service_name("/parameter_events", false);
+  auto prefix = "qos_overrides." + final_topic_name + ".";
+  std::array<rclcpp::QosPolicyKind, 4> policies = {
+    rclcpp::QosPolicyKind::Depth,
+    rclcpp::QosPolicyKind::Durability,
+    rclcpp::QosPolicyKind::History,
+    rclcpp::QosPolicyKind::Reliability,
+  };
+  for (const auto & policy : policies) {
+    auto param_name = prefix + rclcpp::qos_policy_kind_to_cstr(policy);
+    auto it = parameter_overrides.find(param_name);
+    auto value = it != parameter_overrides.end() ?
+      it->second :
+      rclcpp::detail::get_default_qos_param_value(policy, options.parameter_event_qos());
+    rclcpp::detail::apply_qos_override(policy, value, final_qos);
+  }
+  return final_qos;
+}
+
 Node::Node(
   const std::string & node_name,
   const std::string & namespace_,
@@ -126,7 +172,9 @@ Node::Node(
       options.parameter_overrides(),
       options.start_parameter_services(),
       options.start_parameter_event_publisher(),
-      options.parameter_event_qos(),
+      // This is needed in order to apply parameter overrides to the qos profile provided in
+      // options.
+      get_parameter_events_qos(*node_base_, options),
       options.parameter_event_publisher_options(),
       options.allow_undeclared_parameters(),
       options.automatically_declare_parameters_from_overrides()
@@ -139,13 +187,28 @@ Node::Node(
       node_logging_,
       node_clock_,
       node_parameters_,
-      options.clock_qos()
+      options.clock_qos(),
+      options.use_clock_thread()
     )),
   node_waitables_(new rclcpp::node_interfaces::NodeWaitables(node_base_.get())),
   node_options_(options),
   sub_namespace_(""),
   effective_namespace_(create_effective_namespace(this->get_namespace(), sub_namespace_))
 {
+  // we have got what we wanted directly from the overrides,
+  // but declare the parameters anyway so they are visible.
+  rclcpp::detail::declare_qos_parameters(
+    rclcpp::QosOverridingOptions
+  {
+    QosPolicyKind::Depth,
+    QosPolicyKind::Durability,
+    QosPolicyKind::History,
+    QosPolicyKind::Reliability,
+  },
+    node_parameters_,
+    node_topics_->resolve_topic_name("/parameter_events"),
+    options.parameter_event_qos(),
+    rclcpp::detail::PublisherQosParametersTraits{});
 }
 
 Node::Node(
@@ -185,7 +248,18 @@ Node::Node(
 }
 
 Node::~Node()
-{}
+{
+  // release sub-interfaces in an order that allows them to consult with node_base during tear-down
+  node_waitables_.reset();
+  node_time_source_.reset();
+  node_parameters_.reset();
+  node_clock_.reset();
+  node_services_.reset();
+  node_topics_.reset();
+  node_timers_.reset();
+  node_logging_.reset();
+  node_graph_.reset();
+}
 
 const char *
 Node::get_name() const
@@ -219,6 +293,24 @@ Node::create_callback_group(
   return node_base_->create_callback_group(group_type, automatically_add_to_executor_with_node);
 }
 
+const rclcpp::ParameterValue &
+Node::declare_parameter(const std::string & name)
+{
+#ifndef _WIN32
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#else
+# pragma warning(push)
+# pragma warning(disable: 4996)
+#endif
+  return this->node_parameters_->declare_parameter(name);
+#ifndef _WIN32
+# pragma GCC diagnostic pop
+#else
+# pragma warning(pop)
+#endif
+}
+
 const rclcpp::ParameterValue &
 Node::declare_parameter(
   const std::string & name,
@@ -233,6 +325,20 @@ Node::declare_parameter(
     ignore_override);
 }
 
+const rclcpp::ParameterValue &
+Node::declare_parameter(
+  const std::string & name,
+  rclcpp::ParameterType type,
+  const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor,
+  bool ignore_override)
+{
+  return this->node_parameters_->declare_parameter(
+    name,
+    type,
+    parameter_descriptor,
+    ignore_override);
+}
+
 void
 Node::undeclare_parameter(const std::string & name)
 {

rclcpp/src/rclcpp/node_interfaces/node_base.cpp

@@ -70,6 +70,7 @@ NodeBase::NodeBase(
   std::shared_ptr<std::recursive_mutex> logging_mutex = get_global_logging_mutex();
   {
     std::lock_guard<std::recursive_mutex> guard(*logging_mutex);
+    // TODO(ivanpauno): /rosout Qos should be reconfigurable.
     // TODO(ivanpauno): Instead of mutually excluding rcl_node_init with the global logger mutex,
     // rcl_logging_rosout_init_publisher_for_node could be decoupled from there and be called
     // here directly.
@@ -288,3 +289,24 @@ NodeBase::get_enable_topic_statistics_default() const
 {
   return enable_topic_statistics_default_;
 }
+
+std::string
+NodeBase::resolve_topic_or_service_name(
+  const std::string & name, bool is_service, bool only_expand) const
+{
+  char * output_cstr = NULL;
+  auto allocator = rcl_get_default_allocator();
+  rcl_ret_t ret = rcl_node_resolve_name(
+    node_handle_.get(),
+    name.c_str(),
+    allocator,
+    is_service,
+    only_expand,
+    &output_cstr);
+  if (RCL_RET_OK != ret) {
+    throw_from_rcl_error(ret, "failed to resolve name", rcl_get_error_state());
+  }
+  std::string output{output_cstr};
+  allocator.deallocate(output_cstr, allocator.state);
+  return output;
+}

rclcpp/src/rclcpp/node_interfaces/node_parameters.cpp

@@ -16,8 +16,10 @@
 
 #include <rcl_yaml_param_parser/parser.h>
 
+#include <array>
 #include <cmath>
 #include <cstdlib>
+#include <cstring>
 #include <functional>
 #include <limits>
 #include <map>
@@ -34,6 +36,8 @@
 #include "rcutils/logging_macros.h"
 #include "rmw/qos_profiles.h"
 
+#include "../detail/resolve_parameter_overrides.hpp"
+
 using rclcpp::node_interfaces::NodeParameters;
 
 NodeParameters::NodeParameters(
@@ -67,6 +71,7 @@ NodeParameters::NodeParameters(
   }
 
   if (start_parameter_event_publisher) {
+    // TODO(ivanpauno): Qos of the `/parameters_event` topic should be somehow overridable.
     events_publisher_ = rclcpp::create_publisher<MessageT, AllocatorT, PublisherT>(
       node_topics,
       "/parameter_events",
@@ -84,60 +89,27 @@ NodeParameters::NodeParameters(
     throw std::runtime_error("Need valid node options in NodeParameters");
   }
 
-  std::vector<const rcl_arguments_t *> argument_sources;
-  // global before local so that local overwrites global
+  const rcl_arguments_t * global_args = nullptr;
   if (options->use_global_arguments) {
     auto context_ptr = node_base->get_context()->get_rcl_context();
-    argument_sources.push_back(&(context_ptr->global_arguments));
+    global_args = &(context_ptr->global_arguments);
   }
-  argument_sources.push_back(&options->arguments);
-
-  // Get fully qualified node name post-remapping to use to find node's params in yaml files
   combined_name_ = node_base->get_fully_qualified_name();
 
-  for (const rcl_arguments_t * source : argument_sources) {
-    rcl_params_t * params = NULL;
-    rcl_ret_t ret = rcl_arguments_get_param_overrides(source, &params);
-    if (RCL_RET_OK != ret) {
-      rclcpp::exceptions::throw_from_rcl_error(ret);
-    }
-    if (params) {
-      auto cleanup_params = make_scope_exit(
-        [params]() {
-          rcl_yaml_node_struct_fini(params);
-        });
-      rclcpp::ParameterMap initial_map = rclcpp::parameter_map_from(params);
-
-      // Enforce wildcard matching precedence
-      // TODO(cottsay) implement further wildcard matching
-      const std::vector<std::string> node_matching_names{"/**", combined_name_};
-      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)) {
-            parameter_overrides_[param.get_name()] =
-              rclcpp::ParameterValue(param.get_value_message());
-          }
-        }
-      }
-    }
-  }
-
-  // parameter overrides passed to constructor will overwrite overrides from yaml file sources
-  for (auto & param : parameter_overrides) {
-    parameter_overrides_[param.get_name()] =
-      rclcpp::ParameterValue(param.get_value_message());
-  }
+  parameter_overrides_ = rclcpp::detail::resolve_parameter_overrides(
+    combined_name_, parameter_overrides, &options->arguments, global_args);
 
   // 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,
-          rcl_interfaces::msg::ParameterDescriptor(),
+          descriptor,
           true);
       }
     }
@@ -164,14 +136,13 @@ __are_doubles_equal(double x, double y, double ulp = 100.0)
   return std::abs(x - y) <= std::numeric_limits<double>::epsilon() * std::abs(x + y) * ulp;
 }
 
-RCLCPP_LOCAL
-inline
-void
-format_reason(std::string & reason, const std::string & name, const char * range_type)
+static
+std::string
+format_range_reason(const std::string & name, const char * range_type)
 {
   std::ostringstream ss;
   ss << "Parameter {" << name << "} doesn't comply with " << range_type << " range.";
-  reason = ss.str();
+  return ss.str();
 }
 
 RCLCPP_LOCAL
@@ -190,7 +161,7 @@ __check_parameter_value_in_range(
     }
     if ((v < integer_range.from_value) || (v > integer_range.to_value)) {
       result.successful = false;
-      format_reason(result.reason, descriptor.name, "integer");
+      result.reason = format_range_reason(descriptor.name, "integer");
       return result;
     }
     if (integer_range.step == 0) {
@@ -200,7 +171,7 @@ __check_parameter_value_in_range(
       return result;
     }
     result.successful = false;
-    format_reason(result.reason, descriptor.name, "integer");
+    result.reason = format_range_reason(descriptor.name, "integer");
     return result;
   }
 
@@ -212,7 +183,7 @@ __check_parameter_value_in_range(
     }
     if ((v < fp_range.from_value) || (v > fp_range.to_value)) {
       result.successful = false;
-      format_reason(result.reason, descriptor.name, "floating point");
+      result.reason = format_range_reason(descriptor.name, "floating point");
       return result;
     }
     if (fp_range.step == 0.0) {
@@ -223,29 +194,62 @@ __check_parameter_value_in_range(
       return result;
     }
     result.successful = false;
-    format_reason(result.reason, descriptor.name, "floating point");
+    result.reason = format_range_reason(descriptor.name, "floating point");
     return result;
   }
   return result;
 }
 
+static
+std::string
+format_type_reason(
+  const std::string & name, const std::string & old_type, const std::string & new_type)
+{
+  std::ostringstream ss;
+  // WARN: A condition later depends on this message starting with "Wrong parameter type",
+  // check `declare_parameter` if you modify this!
+  ss << "Wrong parameter type, parameter {" << name << "} is of type {" << old_type <<
+    "}, setting it to {" << new_type << "} is not allowed.";
+  return ss.str();
+}
+
 // Return true if parameter values comply with the descriptors in parameter_infos.
 RCLCPP_LOCAL
 rcl_interfaces::msg::SetParametersResult
 __check_parameters(
   std::map<std::string, rclcpp::node_interfaces::ParameterInfo> & parameter_infos,
-  const std::vector<rclcpp::Parameter> & parameters)
+  const std::vector<rclcpp::Parameter> & parameters,
+  bool allow_undeclared)
 {
   rcl_interfaces::msg::SetParametersResult result;
   result.successful = true;
   for (const rclcpp::Parameter & parameter : parameters) {
-    const rcl_interfaces::msg::ParameterDescriptor & descriptor =
-      parameter_infos[parameter.get_name()].descriptor;
+    std::string name = parameter.get_name();
+    rcl_interfaces::msg::ParameterDescriptor descriptor;
+    if (allow_undeclared) {
+      auto it = parameter_infos.find(name);
+      if (it != parameter_infos.cend()) {
+        descriptor = it->second.descriptor;
+      } else {
+        // implicitly declared parameters are dinamically typed!
+        descriptor.dynamic_typing = true;
+      }
+    } else {
+      descriptor = parameter_infos[name].descriptor;
+    }
+    const auto new_type = parameter.get_type();
+    const auto specified_type = static_cast<rclcpp::ParameterType>(descriptor.type);
+    result.successful = descriptor.dynamic_typing || specified_type == new_type;
+    if (!result.successful) {
+      result.reason = format_type_reason(
+        name, rclcpp::to_string(specified_type), rclcpp::to_string(new_type));
+      return result;
+    }
     result = __check_parameter_value_in_range(
       descriptor,
       parameter.get_parameter_value());
     if (!result.successful) {
-      break;
+      return result;
     }
   }
   return result;
@@ -292,16 +296,18 @@ __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)
+  const OnParametersSetCallbackType & callback,
+  bool allow_undeclared = false)
 {
-  // Call the user callback to see if the new value(s) are allowed.
-  rcl_interfaces::msg::SetParametersResult result =
-    __call_on_parameters_set_callbacks(parameters, callback_container, callback);
+  // Check if the value being set complies with the descriptor.
+  rcl_interfaces::msg::SetParametersResult result = __check_parameters(
+    parameter_infos, parameters, allow_undeclared);
   if (!result.successful) {
     return result;
   }
-  // Check if the value being set complies with the descriptor.
-  result = __check_parameters(parameter_infos, parameters);
+  // Call the user callback to see if the new value(s) are allowed.
+  result =
+    __call_on_parameters_set_callbacks(parameters, callback_container, callback);
   if (!result.successful) {
     return result;
   }
@@ -352,6 +358,10 @@ __declare_parameter_common(
     callback_container,
     callback);
 
+  if (!result.successful) {
+    return result;
+  }
+
   // Add declared parameters to storage.
   parameters_out[name] = parameter_infos.at(name);
 
@@ -363,6 +373,99 @@ __declare_parameter_common(
   return result;
 }
 
+static
+const rclcpp::ParameterValue &
+declare_parameter_helper(
+  const std::string & name,
+  rclcpp::ParameterType type,
+  const rclcpp::ParameterValue & default_value,
+  rcl_interfaces::msg::ParameterDescriptor parameter_descriptor,
+  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,
+  rclcpp::Publisher<rcl_interfaces::msg::ParameterEvent> * events_publisher,
+  const std::string & combined_name,
+  rclcpp::node_interfaces::NodeClockInterface & node_clock)
+{
+  // TODO(sloretz) parameter name validation
+  if (name.empty()) {
+    throw rclcpp::exceptions::InvalidParametersException("parameter name must not be empty");
+  }
+
+  // Error if this parameter has already been declared and is different
+  if (__lockless_has_parameter(parameters, name)) {
+    throw rclcpp::exceptions::ParameterAlreadyDeclaredException(
+            "parameter '" + name + "' has already been declared");
+  }
+
+  if (!parameter_descriptor.dynamic_typing) {
+    if (rclcpp::PARAMETER_NOT_SET == type) {
+      type = default_value.get_type();
+    }
+    if (rclcpp::PARAMETER_NOT_SET == type) {
+      throw rclcpp::exceptions::InvalidParameterTypeException{
+              name,
+              "cannot declare a statically typed parameter with an uninitialized value"
+      };
+    }
+    parameter_descriptor.type = static_cast<uint8_t>(type);
+  }
+
+  if (
+    rclcpp::PARAMETER_NOT_SET == default_value.get_type() &&
+    overrides.find(name) == overrides.end() &&
+    parameter_descriptor.dynamic_typing == false)
+  {
+    throw rclcpp::exceptions::NoParameterOverrideProvided(name);
+  }
+
+  rcl_interfaces::msg::ParameterEvent parameter_event;
+  auto result = __declare_parameter_common(
+    name,
+    default_value,
+    parameter_descriptor,
+    parameters,
+    overrides,
+    callback_container,
+    callback,
+    &parameter_event,
+    ignore_override);
+
+  // If it failed to be set, then throw an exception.
+  if (!result.successful) {
+    constexpr const char type_error_msg_start[] = "Wrong parameter type";
+    if (
+      0u == std::strncmp(
+        result.reason.c_str(), type_error_msg_start, sizeof(type_error_msg_start) - 1))
+    {
+      // TODO(ivanpauno): Refactor the logic so we don't need the above `strncmp` and we can
+      // detect between both exceptions more elegantly.
+      throw rclcpp::exceptions::InvalidParameterTypeException(name, result.reason);
+    }
+    throw rclcpp::exceptions::InvalidParameterValueException(
+            "parameter '" + name + "' could not be set: " + result.reason);
+  }
+
+  // Publish if events_publisher_ is not nullptr, which may be if disabled in the constructor.
+  if (nullptr != events_publisher) {
+    parameter_event.node = combined_name;
+    parameter_event.stamp = node_clock.get_clock()->now();
+    events_publisher->publish(parameter_event);
+  }
+
+  return parameters.at(name).value;
+}
+
+const rclcpp::ParameterValue &
+NodeParameters::declare_parameter(const std::string & name)
+{
+  rcl_interfaces::msg::ParameterDescriptor descriptor;
+  descriptor.dynamic_typing = true;
+  return this->declare_parameter(name, rclcpp::ParameterValue{}, descriptor, false);
+}
+
 const rclcpp::ParameterValue &
 NodeParameters::declare_parameter(
   const std::string & name,
@@ -371,46 +474,57 @@ NodeParameters::declare_parameter(
   bool ignore_override)
 {
   std::lock_guard<std::recursive_mutex> lock(mutex_);
-
   ParameterMutationRecursionGuard guard(parameter_modification_enabled_);
 
-  // TODO(sloretz) parameter name validation
-  if (name.empty()) {
-    throw rclcpp::exceptions::InvalidParametersException("parameter name must not be empty");
-  }
-
-  // Error if this parameter has already been declared and is different
-  if (__lockless_has_parameter(parameters_, name)) {
-    throw rclcpp::exceptions::ParameterAlreadyDeclaredException(
-            "parameter '" + name + "' has already been declared");
-  }
-
-  rcl_interfaces::msg::ParameterEvent parameter_event;
-  auto result = __declare_parameter_common(
+  return declare_parameter_helper(
     name,
+    rclcpp::PARAMETER_NOT_SET,
     default_value,
     parameter_descriptor,
+    ignore_override,
     parameters_,
     parameter_overrides_,
     on_parameters_set_callback_container_,
     on_parameters_set_callback_,
-    &parameter_event,
-    ignore_override);
+    events_publisher_.get(),
+    combined_name_,
+    *node_clock_);
+}
 
-  // If it failed to be set, then throw an exception.
-  if (!result.successful) {
-    throw rclcpp::exceptions::InvalidParameterValueException(
-            "parameter '" + name + "' could not be set: " + result.reason);
+const rclcpp::ParameterValue &
+NodeParameters::declare_parameter(
+  const std::string & name,
+  rclcpp::ParameterType type,
+  const rcl_interfaces::msg::ParameterDescriptor & parameter_descriptor,
+  bool ignore_override)
+{
+  std::lock_guard<std::recursive_mutex> lock(mutex_);
+  ParameterMutationRecursionGuard guard(parameter_modification_enabled_);
+
+  if (rclcpp::PARAMETER_NOT_SET == type) {
+    throw std::invalid_argument{
+            "declare_parameter(): the provided parameter type cannot be rclcpp::PARAMETER_NOT_SET"};
   }
 
-  // Publish if events_publisher_ is not nullptr, which may be if disabled in the constructor.
-  if (nullptr != events_publisher_) {
-    parameter_event.node = combined_name_;
-    parameter_event.stamp = node_clock_->get_clock()->now();
-    events_publisher_->publish(parameter_event);
+  if (parameter_descriptor.dynamic_typing == true) {
+    throw std::invalid_argument{
+            "declare_parameter(): cannot declare parameter of specific type and pass descriptor"
+            "with `dynamic_typing=true`"};
   }
 
-  return parameters_.at(name).value;
+  return declare_parameter_helper(
+    name,
+    type,
+    rclcpp::ParameterValue{},
+    parameter_descriptor,
+    ignore_override,
+    parameters_,
+    parameter_overrides_,
+    on_parameters_set_callback_container_,
+    on_parameters_set_callback_,
+    events_publisher_.get(),
+    combined_name_,
+    *node_clock_);
 }
 
 void
@@ -430,6 +544,10 @@ NodeParameters::undeclare_parameter(const std::string & name)
     throw rclcpp::exceptions::ParameterImmutableException(
             "cannot undeclare parameter '" + name + "' because it is read-only");
   }
+  if (!parameter_info->second.descriptor.dynamic_typing) {
+    throw rclcpp::exceptions::InvalidParameterTypeException{
+            name, "cannot undeclare an statically typed parameter"};
+  }
 
   parameters_.erase(parameter_info);
 }
@@ -523,13 +641,17 @@ NodeParameters::set_parameters_atomically(const std::vector<rclcpp::Parameter> &
   rcl_interfaces::msg::ParameterEvent parameter_event_msg;
   parameter_event_msg.node = combined_name_;
   CallbacksContainerType empty_callback_container;
+
+  // Implicit declare uses dynamic type descriptor.
+  rcl_interfaces::msg::ParameterDescriptor descriptor;
+  descriptor.dynamic_typing = true;
   for (auto parameter_to_be_declared : parameters_to_be_declared) {
     // This should not throw, because we validated the name and checked that
     // the parameter was not already declared.
     result = __declare_parameter_common(
       parameter_to_be_declared->get_name(),
       parameter_to_be_declared->get_parameter_value(),
-      rcl_interfaces::msg::ParameterDescriptor(),  // Implicit declare uses default descriptor.
+      descriptor,
       staged_parameter_changes,
       parameter_overrides_,
       // Only call callbacks once below
@@ -578,6 +700,11 @@ NodeParameters::set_parameters_atomically(const std::vector<rclcpp::Parameter> &
     if (rclcpp::PARAMETER_NOT_SET == parameter.get_type()) {
       auto it = parameters_.find(parameter.get_name());
       if (it != parameters_.end() && rclcpp::PARAMETER_NOT_SET != it->second.value.get_type()) {
+        if (!it->second.descriptor.dynamic_typing) {
+          result.reason = "cannot undeclare an statically typed parameter";
+          result.successful = false;
+          return result;
+        }
         parameters_to_be_undeclared.push_back(&parameter);
       }
     }
@@ -593,7 +720,8 @@ NodeParameters::set_parameters_atomically(const std::vector<rclcpp::Parameter> &
     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_);
+    on_parameters_set_callback_,
+    allow_undeclared_);  // allow undeclared
 
   // If not successful, then stop here.
   if (!result.successful) {
@@ -827,22 +955,6 @@ NodeParameters::list_parameters(const std::vector<std::string> & prefixes, uint6
   return result;
 }
 
-struct HandleCompare
-  : public std::unary_function<OnSetParametersCallbackHandle::WeakPtr, bool>
-{
-  explicit HandleCompare(const OnSetParametersCallbackHandle * const base)
-  : base_(base) {}
-  bool operator()(const OnSetParametersCallbackHandle::WeakPtr & handle)
-  {
-    auto shared_handle = handle.lock();
-    if (base_ == shared_handle.get()) {
-      return true;
-    }
-    return false;
-  }
-  const OnSetParametersCallbackHandle * const base_;
-};
-
 void
 NodeParameters::remove_on_set_parameters_callback(
   const OnSetParametersCallbackHandle * const handle)
@@ -853,7 +965,9 @@ NodeParameters::remove_on_set_parameters_callback(
   auto it = std::find_if(
     on_parameters_set_callback_container_.begin(),
     on_parameters_set_callback_container_.end(),
-    HandleCompare(handle));
+    [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);
   } else {

rclcpp/src/rclcpp/node_interfaces/node_services.cpp

@@ -78,3 +78,9 @@ NodeServices::add_client(
     }
   }
 }
+
+std::string
+NodeServices::resolve_service_name(const std::string & name, bool only_expand) const
+{
+  return node_base_->resolve_topic_or_service_name(name, true, only_expand);
+}

rclcpp/src/rclcpp/node_interfaces/node_time_source.cpp

@@ -27,7 +27,8 @@ NodeTimeSource::NodeTimeSource(
   rclcpp::node_interfaces::NodeLoggingInterface::SharedPtr node_logging,
   rclcpp::node_interfaces::NodeClockInterface::SharedPtr node_clock,
   rclcpp::node_interfaces::NodeParametersInterface::SharedPtr node_parameters,
-  const rclcpp::QoS & qos)
+  const rclcpp::QoS & qos,
+  bool use_clock_thread)
 : node_base_(node_base),
   node_topics_(node_topics),
   node_graph_(node_graph),
@@ -35,7 +36,7 @@ NodeTimeSource::NodeTimeSource(
   node_logging_(node_logging),
   node_clock_(node_clock),
   node_parameters_(node_parameters),
-  time_source_(qos)
+  time_source_(qos, use_clock_thread)
 {
   time_source_.attachNode(
     node_base_,

rclcpp/src/rclcpp/node_interfaces/node_timers.cpp

@@ -16,6 +16,8 @@
 
 #include <string>
 
+#include "tracetools/tracetools.h"
+
 using rclcpp::node_interfaces::NodeTimers;
 
 NodeTimers::NodeTimers(rclcpp::node_interfaces::NodeBaseInterface * node_base)
@@ -44,4 +46,8 @@ NodeTimers::add_timer(
             std::string("Failed to notify wait set on timer creation: ") +
             rmw_get_error_string().str);
   }
+  TRACEPOINT(
+    rclcpp_timer_link_node,
+    static_cast<const void *>(timer->get_timer_handle().get()),
+    static_cast<const void *>(node_base_->get_rcl_node_handle()));
 }

rclcpp/src/rclcpp/node_interfaces/node_topics.cpp

@@ -129,3 +129,9 @@ NodeTopics::get_node_timers_interface() const
 {
   return node_timers_;
 }
+
+std::string
+NodeTopics::resolve_topic_name(const std::string & name, bool only_expand) const
+{
+  return node_base_->resolve_topic_or_service_name(name, false, only_expand);
+}