[foxy] Fix race with launch context changes when loading composable nodes (#166) (#206)

* Fix race with launch context changes when loading composable nodes (#166)

* Fix race with launch context changes when loading composable nodes

This bug was discovered when trying load composable nodes from a GroupAction.
The ROS namespace (and presumably other remaps) pushed onto the context stack
was popped after the LoadComposableNodes execute() function finished.
But because the loading happens asynchronously, we need to make sure we get the
necessary information from the context before execute() finishes.

Signed-off-by: Jacob Perron <[email protected]>

* Add regression tests for LoadComposableNode

Signed-off-by: Jacob Perron <[email protected]>

* Properly shutdown mock conatiner node

Also added some debug logs to the load node action for posterity.

Signed-off-by: Jacob Perron <[email protected]>

* Fix docblock in LoadComposableNodes (#207)

Signed-off-by: Jacob Perron <[email protected]>

Author: jacobperron

launch_ros/launch_ros/actions/load_composable_nodes.py

@@ -82,13 +82,13 @@ def __init__(
 
     def _load_node(
         self,
-        composable_node_description: ComposableNode,
+        request: composition_interfaces.srv.LoadNode.Request,
         context: LaunchContext
     ) -> None:
         """
         Load node synchronously.
 
-        :param composable_node_description: description of composable node to be loaded
+        :param request: service request to load a node
         :param context: current launch context
         """
         while not self.__rclpy_load_node_client.wait_for_service(timeout_sec=1.0):
@@ -99,8 +99,13 @@ def _load_node(
                     )
                 )
                 return
-        request = get_composable_node_load_request(composable_node_description, context)
+        self.__logger.debug(
+            "Calling the '{}' service with request '{}'".format(
+                self.__rclpy_load_node_client.srv_name, request
+            )
+        )
         response = self.__rclpy_load_node_client.call(request)
+        self.__logger.debug("Received response '{}'".format(response))
         node_name = response.full_node_name if response.full_node_name else request.node_name
         if response.success:
             if node_name is not None:
@@ -125,22 +130,22 @@ def _load_node(
 
     def _load_in_sequence(
         self,
-        composable_node_descriptions: List[ComposableNode],
+        load_node_requests: List[composition_interfaces.srv.LoadNode.Request],
         context: LaunchContext
     ) -> None:
         """
         Load composable nodes sequentially.
 
-        :param composable_node_descriptions: descriptions of composable nodes to be loaded
+        :param load_node_requests: a list of LoadNode service requests to execute
         :param context: current launch context
         """
-        next_composable_node_description = composable_node_descriptions[0]
-        composable_node_descriptions = composable_node_descriptions[1:]
-        self._load_node(next_composable_node_description, context)
-        if len(composable_node_descriptions) > 0:
+        next_load_node_request = load_node_requests[0]
+        load_node_requests = load_node_requests[1:]
+        self._load_node(next_load_node_request, context)
+        if len(load_node_requests) > 0:
             context.add_completion_future(
                 context.asyncio_loop.run_in_executor(
-                    None, self._load_in_sequence, composable_node_descriptions, context
+                    None, self._load_in_sequence, load_node_requests, context
                 )
             )
 
@@ -169,9 +174,16 @@ def execute(
             )
         )
 
+        # Generate load requests before execute() exits to avoid race with context changing
+        # due to scope change (e.g. if loading nodes from within a GroupAction).
+        load_node_requests = [
+            get_composable_node_load_request(node_description, context)
+            for node_description in self.__composable_node_descriptions
+        ]
+
         context.add_completion_future(
             context.asyncio_loop.run_in_executor(
-                None, self._load_in_sequence, self.__composable_node_descriptions, context
+                None, self._load_in_sequence, load_node_requests, context
             )
         )
 

test_launch_ros/test/test_launch_ros/actions/test_load_composable_nodes.py

@@ -0,0 +1,281 @@
+# 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.
+
+"""Tests for the LoadComposableNodes Action."""
+
+import threading
+
+from composition_interfaces.srv import LoadNode
+
+from launch import LaunchDescription
+from launch import LaunchService
+from launch.actions import GroupAction
+from launch_ros.actions import LoadComposableNodes
+from launch_ros.actions import PushRosNamespace
+from launch_ros.actions import SetRemap
+from launch_ros.descriptions import ComposableNode
+from launch_ros.utilities import get_node_name_count
+
+import pytest
+
+from rcl_interfaces.msg import ParameterType
+
+import rclpy
+import rclpy.context
+import rclpy.executors
+import rclpy.node
+
+TEST_CONTAINER_NAME = 'mock_component_container'
+TEST_NODE_NAME = 'test_load_composable_nodes_node'
+
+
+class MockComponentContainer(rclpy.node.Node):
+
+    def __init__(self):
+        # List of LoadNode requests received
+        self.requests = []
+
+        self._context = rclpy.context.Context()
+        rclpy.init(context=self._context)
+
+        super().__init__(TEST_CONTAINER_NAME, context=self._context)
+
+        self.load_node_service = self.create_service(
+            LoadNode,
+            '~/_container/load_node',
+            self.load_node_callback
+        )
+
+        self._executor = rclpy.executors.SingleThreadedExecutor(context=self._context)
+
+        # Start spinning in a thread
+        self._thread = threading.Thread(
+            target=rclpy.spin,
+            args=(self, self._executor),
+            daemon=True
+        )
+        self._thread.start()
+
+    def load_node_callback(self, request, response):
+        self.requests.append(request)
+        response.success = True
+        response.full_node_name = f'{request.node_namespace}/{request.node_name}'
+        response.unique_id = len(self.requests)
+        return response
+
+    def shutdown(self):
+        self._executor.shutdown()
+        self.destroy_node()
+        rclpy.shutdown(context=self._context)
+        self._thread.join()
+
+
+def _assert_launch_no_errors(actions):
+    ld = LaunchDescription(actions)
+    ls = LaunchService(debug=True)
+    ls.include_launch_description(ld)
+    assert 0 == ls.run()
+    return ls.context
+
+
+def _load_composable_node(
+    *,
+    package,
+    plugin,
+    name,
+    namespace='',
+    parameters=None,
+    remappings=None,
+    target_container=f'/{TEST_CONTAINER_NAME}'
+):
+    return LoadComposableNodes(
+        target_container=target_container,
+        composable_node_descriptions=[
+            ComposableNode(
+                package=package,
+                plugin=plugin,
+                name=name,
+                namespace=namespace,
+                parameters=parameters,
+                remappings=remappings,
+            )
+        ])
+
+
+@pytest.fixture
+def mock_component_container():
+    container = MockComponentContainer()
+    yield container
+    container.shutdown()
+
+
+def test_load_node(mock_component_container):
+    """Test loading a node."""
+    context = _assert_launch_no_errors([
+        _load_composable_node(
+            package='foo_package',
+            plugin='bar_plugin',
+            name='test_node_name',
+            namespace='test_node_namespace'
+        )
+    ])
+
+    # Check that launch is aware of loaded component
+    assert get_node_name_count(context, '/test_node_namespace/test_node_name') == 1
+
+    # Check that container recieved correct request
+    assert len(mock_component_container.requests) == 1
+    request = mock_component_container.requests[0]
+    assert request.package_name == 'foo_package'
+    assert request.plugin_name == 'bar_plugin'
+    assert request.node_name == 'test_node_name'
+    assert request.node_namespace == '/test_node_namespace'
+    assert len(request.remap_rules) == 0
+    assert len(request.parameters) == 0
+    assert len(request.extra_arguments) == 0
+
+
+def test_load_node_with_remaps(mock_component_container):
+    """Test loading a node with remappings."""
+    context = _assert_launch_no_errors([
+        _load_composable_node(
+            package='foo_package',
+            plugin='bar_plugin',
+            name='test_node_name',
+            namespace='test_node_namespace',
+            remappings=[
+                ('test_topic1', 'test_remap_topic1'),
+                ('test/topic/two', 'test/remap_topic2')
+            ]
+        )
+    ])
+
+    # Check that launch is aware of loaded component
+    assert get_node_name_count(context, '/test_node_namespace/test_node_name') == 1
+
+    # Check that container recieved correct request
+    assert len(mock_component_container.requests) == 1
+    request = mock_component_container.requests[0]
+    assert request.package_name == 'foo_package'
+    assert request.plugin_name == 'bar_plugin'
+    assert request.node_name == 'test_node_name'
+    assert request.node_namespace == '/test_node_namespace'
+    assert len(request.remap_rules) == 2
+    assert request.remap_rules[0] == 'test_topic1:=test_remap_topic1'
+    assert request.remap_rules[1] == 'test/topic/two:=test/remap_topic2'
+    assert len(request.parameters) == 0
+    assert len(request.extra_arguments) == 0
+
+
+def test_load_node_with_params(mock_component_container):
+    """Test loading a node with parameters."""
+    context = _assert_launch_no_errors([
+        _load_composable_node(
+            package='foo_package',
+            plugin='bar_plugin',
+            name='test_node_name',
+            namespace='test_node_namespace',
+            parameters=[{
+                'test_param1': 'test_value_param1',
+                'test.param2': '42.0',
+            }]
+        )
+    ])
+
+    # Check that launch is aware of loaded component
+    assert get_node_name_count(context, '/test_node_namespace/test_node_name') == 1
+
+    # Check that container recieved correct request
+    assert len(mock_component_container.requests) == 1
+    request = mock_component_container.requests[0]
+    assert request.package_name == 'foo_package'
+    assert request.plugin_name == 'bar_plugin'
+    assert request.node_name == 'test_node_name'
+    assert request.node_namespace == '/test_node_namespace'
+    assert len(request.remap_rules) == 0
+    assert len(request.parameters) == 2
+    assert request.parameters[0].name == 'test_param1'
+    assert request.parameters[0].value.type == ParameterType.PARAMETER_STRING
+    assert request.parameters[0].value.string_value == 'test_value_param1'
+    assert request.parameters[1].name == 'test.param2'
+    # TODO(jacobperron): I would expect this to be a double value, but we can only pass strings
+    # assert request.parameters[1].value.type == ParameterType.PARAMETER_DOUBLE
+    # assert request.parameters[1].value.double_value == 42.0
+    assert request.parameters[1].value.string_value == '42.0'
+    assert len(request.extra_arguments) == 0
+
+
+def test_load_node_with_global_remaps_in_group(mock_component_container):
+    """Test loading a node with global remaps scoped to a group."""
+    context = _assert_launch_no_errors([
+        GroupAction(
+            [
+                SetRemap('chatter', 'new_topic_name'),
+                _load_composable_node(
+                    package='foo_package',
+                    plugin='bar_plugin',
+                    name='test_node_name',
+                    namespace='test_node_namespace'
+                ),
+            ],
+            scoped=True,
+        ),
+    ])
+
+    # Check that launch is aware of loaded component
+    assert get_node_name_count(context, '/test_node_namespace/test_node_name') == 1
+
+    # Check that container recieved correct request
+    assert len(mock_component_container.requests) == 1
+    request = mock_component_container.requests[0]
+    assert request.package_name == 'foo_package'
+    assert request.plugin_name == 'bar_plugin'
+    assert request.node_name == 'test_node_name'
+    assert request.node_namespace == '/test_node_namespace'
+    assert len(request.remap_rules) == 1
+    assert request.remap_rules[0] == 'chatter:=new_topic_name'
+    assert len(request.parameters) == 0
+    assert len(request.extra_arguments) == 0
+
+
+def test_load_node_with_namespace_in_group(mock_component_container):
+    """Test loading a node with namespace scoped to a group."""
+    context = _assert_launch_no_errors([
+        GroupAction(
+            [
+                PushRosNamespace('foo'),
+                _load_composable_node(
+                    package='foo_package',
+                    plugin='bar_plugin',
+                    name='test_node_name',
+                    namespace='test_node_namespace'
+                ),
+            ],
+            scoped=True,
+        ),
+    ])
+
+    # Check that launch is aware of loaded component
+    assert get_node_name_count(context, '/foo/test_node_namespace/test_node_name') == 1
+
+    # Check that container recieved correct request
+    assert len(mock_component_container.requests) == 1
+    request = mock_component_container.requests[0]
+    assert request.package_name == 'foo_package'
+    assert request.plugin_name == 'bar_plugin'
+    assert request.node_name == 'test_node_name'
+    assert request.node_namespace == '/foo/test_node_namespace'
+    assert len(request.remap_rules) == 0
+    assert len(request.parameters) == 0
+    assert len(request.extra_arguments) == 0