fix: propagate cancelation signal using task store by yarolegovich · Pull Request #272 · a2aproject/a2a-go

yarolegovich · 2026-03-10T09:34:25Z

fixes #245

yarolegovich · 2026-03-10T09:48:40Z

/gemini review

gemini-code-assist · 2026-03-10T10:12:26Z

Summary of Changes

Hello, 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 refines the handling of task cancellation and concurrent modifications within the system. It ensures that cancellation signals are reliably propagated across different components, particularly when multiple operations attempt to modify a task simultaneously. By introducing a dedicated mechanism for reporting the underlying cause of execution failures and integrating the task store more deeply into the processing logic, the changes improve the robustness and clarity of error handling, leading to more predictable system behavior during concurrent task lifecycles.

Highlights

Error Handling Refinement: Updated error handling for concurrent task modifications, replacing a2a.ErrConcurrentTaskModification with taskstore.ErrConcurrentModification and removing the old error definition.
Task Processor Enhancement: Modified the processor and newProcessor functions in a2asrv/agentexec.go to include the taskstore.Store, enabling better state management during task processing and cancellation.
Cancellation Signal Propagation: Implemented logic in processor.Process to handle taskstore.ErrConcurrentModification by checking the task's terminal state and returning appropriate results, ensuring cancellation signals are propagated effectively.
Detailed Error Context: Introduced ExecutionFailureCause in internal/taskexec/api.go's ProcessorResult to provide a more detailed error context for execution failures, and adjusted internal/taskexec/execution_handler.go to return this cause.
New Test Coverage: Added new end-to-end and unit tests (e2e/cancellation_test.go, internal/taskexec/execution_handler_test.go) to validate the correct propagation of cancellation signals and error causes during concurrent operations.

Changelog

a2a/errors.go
- Removed ErrConcurrentTaskModification error definition.
a2asrv/agentexec.go
- Passed f.taskStore to newProcessor in CreateExecutor and CreateCanceler.
- Added store taskstore.Store field to processor struct.
- Updated newProcessor function signature and initialization to accept and store taskstore.Store.
- Modified Process method to handle taskstore.ErrConcurrentModification by checking task status and returning ExecutionFailureCause.
- Updated setTaskFailed to include ExecutionFailureCause in ProcessorResult.
e2e/cancellation_test.go
- Added e2e/cancellation_test.go to test concurrent cancellation scenarios.
internal/taskexec/api.go
- Added ExecutionFailureCause field to ProcessorResult struct.
internal/taskexec/execution_handler.go
- Modified processEvents to return processResult.ExecutionFailureCause.
internal/taskexec/execution_handler_test.go
- Imported taskstore.
- Added TestRunProducerConsumer_CausePropagation to verify error cause propagation.
internal/taskupdate/manager.go
- Replaced a2a.ErrConcurrentTaskModification with taskstore.ErrConcurrentModification in updateStatus.
internal/taskupdate/manager_test.go
- Updated tests to use taskstore.ErrConcurrentModification instead of a2a.ErrConcurrentTaskModification.

Activity

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gemini-code-assist

Code Review

This pull request effectively addresses concurrent task modifications, particularly for propagating cancellation signals. The approach of handling taskstore.ErrConcurrentModification by reloading the task state is robust. The introduction of ExecutionFailureCause to propagate the termination reason to the executor's context is a clean implementation detail. The changes are well-tested with new unit and end-to-end tests. I have one minor suggestion to remove a debugging statement.

gemini-code-assist · 2026-03-10T10:19:14Z

a2asrv/agentexec.go

+		if !storedTask.Task.Status.State.Terminal() {
+			return nil, fmt.Errorf("parallel active execution: %w", processingErr)
+		}
+		fmt.Println("storedTask", storedTask.Task.Status.State)


This fmt.Println appears to be a leftover debugging statement and should be removed to avoid polluting logs.

gemini-code-assist

Code Review

This pull request effectively fixes an issue with propagating cancellation signals across multiple servers by leveraging the shared task store. The approach to handle taskstore.ErrConcurrentModification is robust, and the introduction of ExecutionFailureCause provides a clean mechanism for propagating the cancellation cause to the execution goroutine. The changes are well-tested with new end-to-end and unit tests, ensuring the fix is reliable. I have one minor suggestion to remove a leftover debug print statement.

a2asrv/agentexec.go

e2e/cancellation_test.go

🤖 I have created a release *beep* *boop* --- ## [1.0.0](v1.0.0-alpha.3...v1.0.0) (2026-03-17) ### Features * implement the new rest error handling ([#282](#282)) ([a3bda30](a3bda30)) * use v2 suffix for module ID and provide compat support ([#270](#270)) ([dd1b6ba](dd1b6ba)), closes [#250](#250) ### Bug Fixes * a2asrv jsonrpc Content-Type ([#265](#265)) ([2568a46](2568a46)) * bugs before going from alpha ([#279](#279)) ([b1f055c](b1f055c)) * GetTaskRequest nil pointer assignment check ([#258](#258)) ([440bb79](440bb79)) * inject headers into service params ([#277](#277)) ([d33f3bd](d33f3bd)), closes [#275](#275) * propagate cancelation signal using task store ([#272](#272)) ([5e1d462](5e1d462)), closes [#245](#245) * regenerate spec and fix returnImmediately ([#284](#284)) ([2eee0b9](2eee0b9)) * task modified after save ([#266](#266)) ([c15febe](c15febe)) * taskupdater result mutable ([#274](#274)) ([6038d92](6038d92)) * update pushsender ([#256](#256)) ([5f7a594](5f7a594)) * use enum values as in the spec ([#261](#261)) ([eb98981](eb98981)), closes [#251](#251) ### Documentation * **a2asrv:** add Example_* test functions for pkg.go.dev documentation ([#262](#262)) ([7888e37](7888e37)) * add example tests a2a ([#240](#240)) ([4fe08a9](4fe08a9)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

yarolegovich added 3 commits March 10, 2026 09:23

correctly handle concurrent cancelations

76120ca

deduplicate error

0c4427f

Merge branch 'main' into yarolegovich/propagate-cancel-new

4359d61

yarolegovich requested a review from nahapetyan-serob March 10, 2026 09:36

yarolegovich changed the title ~~fix: propagate cancel new~~ fix: propagate cancelation signal using task store Mar 10, 2026

gemini-code-assist bot reviewed Mar 10, 2026

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nahapetyan-serob approved these changes Mar 10, 2026

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e2e/cancellation_test.go Outdated Show resolved Hide resolved

cleanup

2caa14f

yarolegovich merged commit 5e1d462 into main Mar 10, 2026
4 checks passed

yarolegovich deleted the yarolegovich/propagate-cancel-new branch March 10, 2026 12:28

a2a-bot mentioned this pull request Mar 10, 2026

chore(main): release 1.0.0 #252

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fix: propagate cancelation signal using task store#272

fix: propagate cancelation signal using task store#272
yarolegovich merged 4 commits intomainfrom
yarolegovich/propagate-cancel-new

yarolegovich commented Mar 10, 2026

Uh oh!

yarolegovich commented Mar 10, 2026

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yarolegovich commented Mar 10, 2026

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yarolegovich commented Mar 10, 2026

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gemini-code-assist bot commented Mar 10, 2026

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