Autostarting lifecycle nodes and example launch file demo #430

SteveMacenski · 2024-12-20T00:11:44Z

This resolves #418 which implements autostarting lifecycle nodes. This is complete and ready for a review

You'll notice a couple of key changes worth explaining:

There is a new is_lifecycle_node attribute of the node and lifecycle nodes which is needed to remove a circular dependency on the LifecycleNode within the LifecycleTransition class which only is type checking. I replace this type check with checking if a non-None object (1) has the attribute at all and (2) has a lifecycle attribute with appropriate logging between the difference of a non-lifecycle node being attempted vs a non-node. This has been tested as well to function using the demos.
You will also notice that I refactored lifecycle node to have a separate util LifecycleEventManager, who handles the event emitting, handling, and topic listening for lifecycle nodes. This way, this can be used in lifecycle-components as well! No changes were made here except removing the self.__current_state variable which was completely unused. The LifecycleEventManager is only created if the node requests autostart at Launch time and otherwise has no overhead nor exposes the interfaces/event handler/emitter if its a non-lifecycle node.
The component nodes don't add a / before the node names with the namespaces. This messes with the node event matcher. I add in a leading / so that the action.node_name == node_name which has the / forcably applied in the node event matcher
I tested LifecycleNode, ComposableNodeContainer, LoadCompoableNodes for all cases: autostart=True autostart=False, and autostart field not supplied. You can also run any experiments you like using the 2 extra launch files I provide in the examples directory which shows all the features at work/

SteveMacenski · 2025-01-02T19:52:41Z

@mjcarroll can I get a review on this now that we're back from the holidays? :-)

doisyg · 2025-01-06T11:31:17Z

That would be amazing to have this part of the standard launch!
(and I can already think about a next step: choose if you want to start in Unconfigured, Inactive or Active)

SteveMacenski · 2025-01-16T17:45:05Z

@mjcarroll can I request a review? ❤️

wjwwood

A few questions, but looking pretty good. Thanks for the contribution!

launch_ros/launch_ros/actions/lifecycle_node.py

launch_ros/launch_ros/actions/load_composable_nodes.py

launch_ros/launch_ros/actions/node.py

launch_ros/launch_ros/descriptions/composable_node.py

launch_ros/launch_ros/event_handlers/on_state_transition.py

launch_ros/launch_ros/utilities/lifecycle_event_manager.py

SteveMacenski · 2025-01-17T03:25:22Z

@wjwwood I addressed all of your comments and made a fix by your review requests

wjwwood · 2025-01-28T22:50:50Z

I sent a few responses, resolved a few others. Sorry it took so long to reply, I'll try to be quicker on the next iteration. Thanks again!

SteveMacenski · 2025-01-30T03:02:11Z

I appreciate it, I know this isn't the most active project in the ROS core ecosystem, so I appreciate the attention here :-)

I think I've completed all of the tasks that need to be addressed

wjwwood · 2025-02-04T18:26:37Z

Sorry, one more iteration on the matchers.

SteveMacenski · 2025-02-04T20:31:12Z

See updated comment :-)

wjwwood

looks really close

I continued our conversation on the other thread, and pointed out a potential issue with how autostart is being typed and documented. Other than that, it's mostly cleanup requests after your most recent set of changes.

launch_ros/launch_ros/actions/lifecycle_node.py

launch_ros/launch_ros/actions/node.py

launch_ros/launch_ros/descriptions/composable_node.py

wjwwood

Sorry, after re-reviewing the new class you recently added I found some more things that should be looked into.

launch_ros/launch_ros/descriptions/composable_lifecycle_node.py

launch_ros/launch_ros/actions/load_composable_nodes.py

launch_ros/launch_ros/descriptions/composable_lifecycle_node.py

SteveMacenski · 2025-02-07T23:46:52Z

@wjwwood all of your comments have been addressed, I believe fully now.

I see I must have missed a DCO sign off on my commits, but I really don't want to mess with the git commit history bc I know that'll cause you more trouble re-reviewing not knowing what exactly I just changed.

As the CEO of my own company, I trust that I can just say I give myself permissions to do this. I can also fix DCO after you review and approve if you like. I just don't want to make your life hard.

wjwwood

lgtm

Had a few non-blocking questions, but I think this is good to go with passing CI.

wjwwood · 2025-02-11T18:36:44Z

launch_ros/launch_ros/event_handlers/on_state_transition.py

@@ -51,8 +50,19 @@ def __init__(

        If matcher is given, the other conditions are not considered.
        """
-        if not isinstance(target_lifecycle_node, (LifecycleNode, type(None))):
-            raise RuntimeError("OnStateTransition requires a 'LifecycleNode' action as the target")
+        lifecycle_property = type(target_lifecycle_node).__dict__.get('is_lifecycle_node', None)


Just curious, but is getattr(target_lifecycle_node, 'is_lifecycle_node', None) not sufficient? https://docs.python.org/3/library/functions.html#getattr

The __dict__ method checks the class definition if it has that attribute rather than the individual instance passed into the function. I thought this was a more strict type-checking method of handling it since someone could make an instance with that property instead.

wjwwood · 2025-02-11T18:41:55Z

launch_ros/launch_ros/event_handlers/on_state_transition.py

-        if not isinstance(target_lifecycle_node, (LifecycleNode, type(None))):
-            raise RuntimeError("OnStateTransition requires a 'LifecycleNode' action as the target")
+        lifecycle_property = type(target_lifecycle_node).__dict__.get('is_lifecycle_node', None)
+        if not isinstance(lifecycle_property, (property, type(None))):
+            raise RuntimeError('OnStateTransition requires a "LifecycleNode" action as the target,'
+                               ' target_lifecycle_node is not a node type.')
+
+        if (
+            target_lifecycle_node and
+            hasattr(target_lifecycle_node, 'is_lifecycle_node') and
+            not target_lifecycle_node.is_lifecycle_node
+        ):
+            raise RuntimeError('OnStateTransition requires a "LifecycleNode" action as the target,'
+                               ' target_lifecycle_node is not a lifecycle-enabled node.')


This diff is still a bit confusing to me, why is the original check not sufficient? Is it so we can support non-LifecycleNode based classes?

Also the why do we need the first new condition? It seems like it being either None or a property isn't important, but the second check definitely makes sense with hasattr and checking the value of is_lifecycle_node. Plus the two possible errors seem to be more or less the same (at least based on the error message).

OnStateTransition is now used within the lifecycle node for the LifecycleTransition class, so we can't import LifecycleNode into the class or it creates circular dependencies.

I'm going to fix these up to be more semantically meaningful. The first if is checking if we have the property at all in the class definition and the second is checking if its true. The second hasattr(target_lifecycle_node, 'is_lifecycle_node') is my defensive programming to make sure its there before calling it target_lifecycle_node.is_lifecycle_node , but I suppose at this point it shouldn't necessarily be needed.

I think its nice to have 2 different error logging for either if the property doesn't exist (i.e. not a lifecycle node at all) and also if the value present is non-true.

wjwwood · 2025-02-11T18:52:36Z

Rpr looks like it is failing due to a few small linter issues. After you fix that I'll run full CI with Windows and everything on ci.ros2.org unless someone else beats me to it.

Signed-off-by: Steve Macenski <[email protected]>

SteveMacenski · 2025-02-12T02:44:28Z

Should be good to go. I also resolved the DCO sign off

SteveMacenski mentioned this pull request Dec 20, 2024

Create option for automatic bringup of lifecycle nodes in launch_ros API #418

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wjwwood self-assigned this Jan 16, 2025

wjwwood self-requested a review January 16, 2025 18:30

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SteveMacenski requested a review from wjwwood January 17, 2025 03:25

wjwwood requested changes Feb 7, 2025

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wjwwood reviewed Feb 7, 2025

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SteveMacenski requested a review from wjwwood February 7, 2025 23:46

wjwwood approved these changes Feb 11, 2025

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SteveMacenski added 10 commits February 11, 2025 18:44

autostarting lifecycle nodes and example

277d95c

Signed-off-by: Steve Macenski <[email protected]>

fix linting

e49ed4c

Signed-off-by: Steve Macenski <[email protected]>

fix linting

c41cdcc

Signed-off-by: Steve Macenski <[email protected]>

removing an unused variable

cc3449e

Signed-off-by: Steve Macenski <[email protected]>

initializing a member client as none like sub

e60458a

Signed-off-by: Steve Macenski <[email protected]>

completing auto-start feature for composition nodes

cfc9b53

Signed-off-by: Steve Macenski <[email protected]>

linting

fa0e741

Signed-off-by: Steve Macenski <[email protected]>

final linting fix

f836f4b

Signed-off-by: Steve Macenski <[email protected]>

Resolving issue with StateTransition messages

5d97fd8

Signed-off-by: Steve Macenski <[email protected]>

removing Node's autostart

5e6bdb9

Signed-off-by: Steve Macenski <[email protected]>

SteveMacenski added 11 commits February 11, 2025 18:44

Fixing lifecyclenode type

92997ae

Signed-off-by: Steve Macenski <[email protected]>

update docstring

656b96e

Signed-off-by: Steve Macenski <[email protected]>

adding in composable lifecycle node

2daab8d

Signed-off-by: Steve Macenski <[email protected]>

Adding docstring

ed8a18f

Signed-off-by: Steve Macenski <[email protected]>

require autostart non-None

281035a

Signed-off-by: Steve Macenski <[email protected]>

remove unused imports

a487b95

Signed-off-by: Steve Macenski <[email protected]>

review comments continued

0f7b4a1

Signed-off-by: Steve Macenski <[email protected]>

is lifecycle node and autostart to lifecycle-only classes

04914a4

Signed-off-by: Steve Macenski <[email protected]>

final bits

d125a69

Signed-off-by: Steve Macenski <[email protected]>

whoops, remove the Avatar-inspired printout

7b4fd4a

Signed-off-by: Steve Macenski <[email protected]>

finish linting

e03c8b2

Signed-off-by: Steve Macenski <[email protected]>

SteveMacenski force-pushed the autostart_lifecycle branch from 07c6627 to e03c8b2 Compare February 12, 2025 02:44

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Autostarting lifecycle nodes and example launch file demo #430

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Autostarting lifecycle nodes and example launch file demo #430

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