Introduce EventsExecutor implementation (#1389)

Author: Brad Martin

rclpy/CMakeLists.txt

@@ -17,6 +17,7 @@ endif()
 
 find_package(ament_cmake REQUIRED)
 find_package(ament_cmake_python REQUIRED)
+find_package(Boost REQUIRED)
 find_package(lifecycle_msgs REQUIRED)
 find_package(rcl REQUIRED)
 find_package(rcl_action REQUIRED)
@@ -90,6 +91,9 @@ pybind11_add_module(_rclpy_pybind11 SHARED
   src/rclpy/destroyable.cpp
   src/rclpy/duration.cpp
   src/rclpy/clock_event.cpp
+  src/rclpy/events_executor/events_executor.cpp
+  src/rclpy/events_executor/rcl_support.cpp
+  src/rclpy/events_executor/timers_manager.cpp
   src/rclpy/exceptions.cpp
   src/rclpy/graph.cpp
   src/rclpy/guard_condition.cpp
@@ -121,6 +125,7 @@ target_include_directories(_rclpy_pybind11 PRIVATE
   src/rclpy/
 )
 target_link_libraries(_rclpy_pybind11 PRIVATE
+  Boost::boost
   lifecycle_msgs::lifecycle_msgs__rosidl_generator_c
   lifecycle_msgs::lifecycle_msgs__rosidl_typesupport_c
   rcl::rcl
@@ -182,6 +187,7 @@ if(BUILD_TESTING)
       test/test_create_node.py
       test/test_create_while_spinning.py
       test/test_destruction.py
+      test/test_events_executor.py
       test/test_executor.py
       test/test_expand_topic_name.py
       test/test_guard_condition.py

rclpy/package.xml

@@ -17,6 +17,7 @@
 
   <buildtool_depend>ament_cmake</buildtool_depend>
 
+  <build_depend>boost</build_depend>
   <build_depend>pybind11_vendor</build_depend>
   <build_depend>python3-dev</build_depend>
   <build_depend>rcpputils</build_depend>

rclpy/rclpy/experimental/__init__.py

@@ -0,0 +1,15 @@
+# Copyright 2024 Brad Martin
+#
+# 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.
+
+from .events_executor import EventsExecutor

rclpy/rclpy/experimental/events_executor.py

@@ -0,0 +1,44 @@
+# Copyright 2024 Brad Martin
+# Copyright 2024 Merlin Labs, 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.
+import faulthandler
+import typing
+
+import rclpy.executors
+import rclpy.node
+from rclpy.impl.implementation_singleton import rclpy_implementation as _rclpy
+
+
+# Try to look like we inherit from the rclpy Executor for type checking purposes without
+# getting any of the code from the base class.
+def EventsExecutor(*, context: rclpy.Context | None = None) -> rclpy.executors.Executor:
+    if context is None:
+        context = rclpy.get_default_context()
+
+    # For debugging purposes, if anything goes wrong in C++ make sure we also get a
+    # Python backtrace dumped with the crash.
+    faulthandler.enable()
+
+    ex = typing.cast(rclpy.executors.Executor, _rclpy.EventsExecutor(context))
+
+    # rclpy.Executor does this too.  Note, the context itself is smart enough to check
+    # for bound methods, and check whether the instances they're bound to still exist at
+    # callback time, so we don't have to worry about tearing down this stale callback at
+    # destruction time.
+    # TODO(bmartin427) This should really be done inside of the EventsExecutor
+    # implementation itself, but I'm unable to figure out a pybind11 incantation that
+    # allows me to pass this bound method call from C++.
+    context.on_shutdown(ex.wake)
+
+    return ex

rclpy/src/rclpy/_rclpy_pybind11.cpp

@@ -32,6 +32,7 @@
 #include "duration.hpp"
 #include "clock_event.hpp"
 #include "event_handle.hpp"
+#include "events_executor/events_executor.hpp"
 #include "exceptions.hpp"
 #include "graph.hpp"
 #include "guard_condition.hpp"
@@ -247,4 +248,6 @@ PYBIND11_MODULE(_rclpy_pybind11, m) {
   rclpy::define_signal_handler_api(m);
   rclpy::define_clock_event(m);
   rclpy::define_lifecycle_api(m);
+
+  rclpy::events_executor::define_events_executor(m);
 }