Add ActionServer #270

jacobperron · 2019-02-06T07:17:24Z

Resolves #257

Similar to ActionClient, ActionServer is implemented as a Waitable and the user interacts with goals via ServerGoalHandle objects.

This is a work in progress. Still need to implement the "get result" logic, add documentation, and some more tests. I separated some changes to _rclpy.c into #269 to avoid adding more to this large change. Since this PR is based on that branch, #269 should be resolved first.

jacobperron · 2019-02-07T01:01:44Z

Rooting out any cross-platform issues:

Linux
Linux-aarch64
macOS
Windows

jacobperron · 2019-02-07T20:14:21Z

Since this is a large PR, I think it can start being reviewed while I try to resolve two outstanding issues:

Feedback messages aren't making it to action clients (but the mock action client used in the tests appears to work).
Tests involving a MultiThreadedExecutor timeout (Tests with MultiThreadedExecutor time out on some CI instances #268)

jacobperron · 2019-02-08T17:45:35Z

Feedback messages aren't making it to action clients (but the mock action client used in the tests appears to work).

This is because I forgot to set the goal ID when publishing feedback messages.

jacobperron · 2019-02-11T18:40:08Z

@sloretz Please take a look at c2026b5. It is an attempt to fix a scenario where 'done callbacks' for futures were not being called, specifically when result responses are ready for Action Servers. I'm not sure if this is the right thing to do.

sloretz · 2019-02-11T18:43:03Z

@sloretz Please take a look at c2026b5. It is an attempt to fix a scenario where 'done callbacks' for futures were not being called,

@jacobperron Looking at it now. Mind moving it to a separate PR ~~with a test~~? (Edit: oops, it already has a test)

jacobperron · 2019-02-11T18:47:14Z

Looking at it now. Mind moving it to a separate PR with a test?

Done #272

rclpy/test/action/test_server.py

sloretz · 2019-02-12T16:53:38Z

rclpy/rclpy/action/server.py

+
+        goal_handle._update_state(GoalEvent.EXECUTE)
+        # Call user execute callback
+        execute_result = await await_or_execute(self._execute_callback, goal_handle)


This looks like it is calling the execute_callback even if the user said ACCEPT_AND_DEFER.

sloretz · 2019-02-12T17:02:00Z

rclpy/rclpy/action/server.py

+        goal_handle._update_state(GoalEvent.EXECUTE)
+        # Call user execute callback
+        execute_result = await await_or_execute(self._execute_callback, goal_handle)
+        # If user did not trigger a terminal state, assume success


If an execute callback returns without reaching a terminal state I would assume aborted.

sloretz · 2019-02-12T17:13:06Z

rclpy/rclpy/action/server.py

+
+        self._node.get_logger().debug('New goal accepted: {0}'.format(goal_uuid.uuid))
+
+        goal_handle._update_state(GoalEvent.EXECUTE)


This looks like it is setting the goal handle to EXECUTE even if the user chose ACCEPT_AND_DEFER. In rclcpp instead of an execute_callback there is handle_accepted. If the user says ACCEPT_AND_DEFER then it arrives at that callback in state ACCEPTED.

If an execute_callback is provided then it should be separate from handle_accepted. Maybe add the execute_callback as a task to the executor if handle_accepted returns and the goal handle is not at a terminal state?

I... deferred implementing the defer logic. I meant to make a note of it.

Originally I was thinking that we could provide an API via the GoalHandle to execute a deferred goal. E.g. def execute(callback=None) where the callback will optionally override a previous established callback. This function will schedule the callback (if there is one) with the executor.

I like the idea of the execute_callback as a way to let the action server handle scheduling execution with the executor. I think this puts less burden on the user; not having to manage threads. Do you think this is something rclcpp_action is missing?

Reflecting on the rclcpp action server, I think it makes sense to take a handle_accepted callback in rclpy's action server as well. The handle_accepted makes a nice venue for providing the user with a reference to the goal handle.

I like the idea of the execute_callback as a way to let the action server handle scheduling execution with the executor. I think this puts less burden on the user; not having to manage threads. Do you think this is something rclcpp_action is missing?

I agree an execute_callback is convenient. I've assumed in rclcpp_action an execute callback would be provided by a class like ROS 1's SimpleActionServer. It should only be invoked after a goal transitions to EXECUTING though. Right now I don't see a way to make a python action server queue goals instead of executing them all in parallel.

Looking back, I'm not sure ACCEPT_AND_EXECUTE and ACCEPT_AND_DEFER are necessary. The same thing could be accomplished by whether or not handle_goal changed the state to EXECUTING .

Looking back, I'm not sure ACCEPT_AND_EXECUTE and ACCEPT_AND_DEFER are necessary.

Agreed.

I've made an update in 9a15695 that adds a handle_accepted_callback in which the user can optionally call goal_handle.execute(), or hold onto the goal handle to execute later (ie. defer).

Right now I don't see a way to make a python action server queue goals instead of executing them all in parallel

With the updated examples, I believe an action server that queues goals could be implemented in Python by adapting the "single goal" example. Instead of aborting newly received goals, it could queue them instead.

If the user doesn't mind ignoring cancel requests, then a SingleThreadedExecutor could be used to create a queuing behavior.

jacobperron · 2019-02-13T02:56:07Z

Rebased on #275, which is required for creating tasks associated with user callbacks with the executor.
The Waitable.add_future mechanism is not as reliable since it needs something in the wait set to be ready for rcl_wait to wake up.

I'm considering replacing the add_future API introduced in #262 with direct calls to Executor.create_task().

sloretz

All minor comments, I didn't test manually but the code LGTM

rclpy/rclpy/action/server.py

rclpy/src/rclpy/_rclpy_action.c

jacobperron · 2019-02-14T01:14:00Z

@sloretz Thank you for the reviews 🙇‍♂️

In addition to addressing your latest comments, I've resolved an issue for the scenario where a goal is deferred, canceled, and then executed in 093d52d.

I've also pushed an example of a goal being deferred in ros2/examples#222.

sloretz · 2019-02-14T19:18:13Z

rclpy/rclpy/action/server.py

+        # It's possible that there has been a request to cancel the goal prior to executing.
+        # In this case we want to avoid the illegal state transition to EXECUTING
+        # but still call the users execute callback to let them handle canceling the goal.
+        if not self.is_cancel_requested:


Does is_cancel_requested mean the cancellation was accepted? If this only means it was requested then what happens if: a goal to be requested to be canceled, the execute callback is called but the state transition to EXECUTE is skipped, then the cancellation request rejected, and finally the execute callback tries to set a terminal state? It looks like it might try to transition from ACCEPTED -> SUCCEEDED/ABORTED which isn't an allowed transition.

Does is_cancel_requested mean the cancellation was accepted?

Yes. The cancellation request was accepted and the goal is in the CANCELING state.

rclpy/rclpy/rclpy/action/server.py

Lines 102 to 103 in b037186

def is_cancel_requested(self):

return GoalStatus.STATUS_CANCELING == self.status

jacobperron · 2019-02-15T01:17:12Z

Linux
Linux-aarch64
macOS
Windows

* Add Action server functions to extension module * Separated service related macros into separate request and response calls * Add server goal handle functions to extension module * Update Action extension module to use conversion functions * Add partial implementation of Python ActionServer * Handles goal and cancel requests, responds, and calls user-defined functions for executing goals. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

And some linting. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Pass an optional 'result_timeout' argument to the constructor specififying how long after a goal is completed to keep a reference to the result. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

The goal status array is published whenever a goal state is updated. Published feedback messages should have the goal ID field populated, otherwise the message will be ignored at the rcl layer. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Upon accepting a goal, the provided `handle_accepted_callback` is called with a reference to the goal handle. The user can then decide to execute the goal or defer. If `handle_accepted_callback` is not provided, then the default behavior is to execute the goal handle immediately. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

* Goal should first transition to CANCELING before CANCELED * Handle case where goal skips the EXECUTING state if deferred (accepted, but not executed) and then canceled Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

jacobperron · 2019-02-15T19:30:43Z

Rebased on master.

jacobperron · 2019-02-19T19:51:34Z

Linux
Linux-aarch64
macOS
Windows

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

This resolves test errors that were present in Windows builds. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

jacobperron · 2019-02-21T01:10:56Z

Hopefully, fixed the Windows build 🤞

Linux
Linux-aarch64
macOS
Windows

jacobperron · 2019-02-21T18:42:24Z

@sloretz Test failures are unrelated.
This is ready for another round of review :)

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

* Add Action server functions to extension module * Separated service related macros into separate request and response calls * Add server goal handle functions to extension module * Update Action extension module to use conversion functions * Add implementation of Python ActionServer * Handles goal and cancel requests, responds, and calls user-defined functions for executing goals. * Handle result requests * Handle expired goals * Publish goal status array and feedback * Add `handle_accepted_callback` to ActionServer Upon accepting a goal, the provided `handle_accepted_callback` is called with a reference to the goal handle. The user can then decide to execute the goal or defer. If `handle_accepted_callback` is not provided, then the default behavior is to execute the goal handle immediately. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

* Add Action Client (#262) * Add rclpy_action module With functions for creating and destroying action clients. * Implement action client * Move common conversion function and typedefs to shared header file (impl/common.h) * Add tests using mock action server * Add action module for aggregating action related submodules * Extend Waitable API so executors are aware of Futures * Move check_for_type_support() to its own module Signed-off-by: Jacob Perron <jacob@openrobotics.org> * Fix Executor not executing tasks if there are no ready entities in the wait set (#272) If a task is created, then trigger the Executors guard condition. This will wake any blocking call to `rcl_wait()`. In this scenario, no work is yielded, so we also have to move the check for 'in-progress' tasks into the wait loop. Added a unit test to reproduce the issue. This resolves an issue in some cases where the result response from the action server is never processed, therefore never reaching the action client. Signed-off-by: Jacob Perron <jacob@openrobotics.org> * Fix Node's reference to executor (#275) Previously, if a `Node` was added to an `Executor` using the executors `add_node` method, then nodes `executor` property would return `None`. Signed-off-by: Jacob Perron <jacob@openrobotics.org> * Abstract type conversions into functions (#269) * Abstract type conversions into functions This helps with readability and maintainability. Also eliminated use of assertions during conversions, defering to exceptions. * Move common C functions to a shared library 'rclpy_common' Signed-off-by: Jacob Perron <jacob@openrobotics.org> * Add ActionServer (#270) * Add Action server functions to extension module * Separated service related macros into separate request and response calls * Add server goal handle functions to extension module * Update Action extension module to use conversion functions * Add implementation of Python ActionServer * Handles goal and cancel requests, responds, and calls user-defined functions for executing goals. * Handle result requests * Handle expired goals * Publish goal status array and feedback * Add `handle_accepted_callback` to ActionServer Upon accepting a goal, the provided `handle_accepted_callback` is called with a reference to the goal handle. The user can then decide to execute the goal or defer. If `handle_accepted_callback` is not provided, then the default behavior is to execute the goal handle immediately. Signed-off-by: Jacob Perron <jacob@openrobotics.org> * Enable test using MultiThreadedExecutor (#280) Signed-off-by: Jacob Perron <jacob@openrobotics.org> * Guard against failed take when taking action messages (#281) Some middlewares (e.g. Connext and OpenSplice) send invalid messages to indicate an instance has been disposed which results in a 'failed take'. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

jacobperron added the in progress Actively being worked on (Kanban column) label Feb 6, 2019

jacobperron self-assigned this Feb 6, 2019

This was referenced Feb 6, 2019

Action implementation #257

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Crystal Patch Release 2 ros2/ros2#647

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Abstract type conversions into functions #269

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rclpy action examples ros2/examples#222

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jacobperron force-pushed the rclpy_action_server branch from c2026b5 to b0589c4 Compare February 13, 2019 02:43

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jacobperron added 9 commits February 15, 2019 11:16

Handle result requests

de91864

And some linting. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Handle expired goals

eaca5a1

Pass an optional 'result_timeout' argument to the constructor specififying how long after a goal is completed to keep a reference to the result. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Fix incorrect module name in _rclpy_action.c

daac625

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Make thread safe and add tests involving concurrent goals

886adec

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Make 'is_active' a property

24f0949

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Add test for feedback

385dd4f

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lint

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jacobperron added 6 commits February 15, 2019 11:16

Minor refactor in action unit tests

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Add test for execute callback that does not set the goal state

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Reject goals processed by malformed goal callbacks

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Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Resolve issues regarding deferring and canceling goals

1b1e4d3

* Goal should first transition to CANCELING before CANCELED * Handle case where goal skips the EXECUTING state if deferred (accepted, but not executed) and then canceled Signed-off-by: Jacob Perron <jacob@openrobotics.org>

Address review

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jacobperron force-pushed the rclpy_action_server branch from b037186 to 449244c Compare February 15, 2019 19:30

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Crystal Patch Release 3 ros2/ros2#656

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Avoid compiler warning from implicit cast

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Use 'L' format for int64_t when calling PyArg_ParseTuple

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This resolves test errors that were present in Windows builds. Signed-off-by: Jacob Perron <jacob@openrobotics.org>

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[mock] migrate components to ROS2 splintered-reality/py_trees_ros_tutorials#5

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Add ActionServer #270

Add ActionServer #270

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		self._node.get_logger().debug('New goal accepted: {0}'.format(goal_uuid.uuid))

		goal_handle._update_state(GoalEvent.EXECUTE)

	def is_cancel_requested(self):
	return GoalStatus.STATUS_CANCELING == self.status

Add ActionServer #270

Add ActionServer #270

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