fix: handle concurrent task completion during cancellation #449
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Summary of Changes
Hello @yarolegovich, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!
This pull request addresses a potential race condition in task cancellation logic. It ensures that the system accurately reports task cancellation status, preventing scenarios where a task might appear canceled but has actually completed concurrently. The changes enhance the reliability of task management by explicitly validating the final state of a task after a cancellation request.
Highlights
- Robust Task Cancellation: Implemented an additional check in on_cancel_task to verify that a task is indeed in a canceled state after a cancellation attempt.
- Error Handling: Introduced TaskNotCancelableError to be raised when a task cannot be successfully canceled due to concurrent completion, preventing false positives.
- Test Coverage: Added a new test case (test_on_cancel_task_completes_during_cancellation) to specifically cover the scenario where a task completes concurrently during a cancellation attempt.
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Code Review
This pull request correctly addresses a race condition where a task could complete while a cancellation request is in flight. The fix in on_cancel_task is robust, ensuring that the task's final state is checked after attempting cancellation. The addition of a new test case to cover this scenario is also great. I have one suggestion to make the new test even more comprehensive by parameterizing it to cover all relevant terminal states.
🤖 I have created a release *beep* *boop* --- ## [0.3.4](v0.3.3...v0.3.4) (2025-09-02) ### Features * Add `ServerCallContext` into task store operations ([#443](#443)) ([e3e5c4b](e3e5c4b)) * Add extensions support to `TaskUpdater.add_artifact` ([#436](#436)) ([598d8a1](598d8a1)) ### Bug Fixes * convert auth_required state in proto utils ([#444](#444)) ([ac12f05](ac12f05)) * handle concurrent task completion during cancellation ([#449](#449)) ([f4c9c18](f4c9c18)) * Remove logger error from init on `rest_adapter` and `jsonrpc_app` ([#439](#439)) ([9193208](9193208)) * resolve streaming endpoint deadlock by pre-consuming request body ([#426](#426)) ([4186731](4186731)) * Sync jsonrpc and rest implementation of authenticated agent card ([#441](#441)) ([9da9ecc](9da9ecc)) ### Performance Improvements * Improve performance and code style for `proto_utils.py` ([#452](#452)) ([1e4b574](1e4b574)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).
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Description
We check that a Task is in a cancellable state before calling
agent_executor.cancel.This doesn't guarantee there's no task completion event in the queue which will be applied before our task cancellation request gets handled.
This PR adds an extra check to ensure that we don't return a Task in a non-cancelled state as a successful cancellation call response. Instead we raise
TaskNotCancelableError.