[zmanian]

Summary

Supersedes #731. Fixes the race condition where jobs error out despite completing successfully.

• Root cause: Both execution_loop and the worker wrapper in execute() race to call mark_completed(). The state machine rejects the second Completed -> Completed transition, causing the job to error out.
• Fix: Narrowly allow only the Completed -> Completed self-transition as idempotent -- early return with tracing::debug! log, no duplicate history entry. All other self-transitions (Pending -> Pending, InProgress -> InProgress, etc.) remain rejected to preserve state machine strictness.
• Updated test: test_mark_completed_twice_returns_error renamed to test_mark_completed_twice_is_idempotent and updated to expect Ok.
• New regression tests: test_completed_to_completed_is_idempotent (state-level) and test_other_self_transitions_still_rejected (ensures narrow scope).

Addresses @zmanian's review feedback on #731:

• Scoped to only Completed -> Completed (not all self-transitions)
• Added tracing::debug! in the idempotent early-return path
• Updated and added regression tests

Test plan

• cargo check passes
• cargo test --lib context -- all 79 tests pass (2 new)
• cargo clippy --all --tests -- zero warnings
• Manual: trigger concurrent mark_completed calls to verify no error

Closes #731

Generated with Claude Code

[gemini-code-assist]

Summary of Changes

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This pull request introduces a critical fix for a race condition within the job execution system. Previously, jobs that completed successfully could still report an error if both the execution loop and the worker wrapper attempted to mark them as completed concurrently. By making the Completed -> Completed state transition idempotent, the system now gracefully handles these concurrent calls, preventing erroneous job failures and significantly improving the robustness and reliability of job processing.

Highlights

• Race Condition Fix: Resolved a race condition where jobs could error out despite successful completion due to concurrent mark_completed() calls from the execution loop and worker wrapper.
• Idempotent Transition: Made the Completed -> Completed state transition idempotent, allowing multiple calls to mark_completed() without error, treating subsequent calls as harmless no-ops.
• Strictness Maintained: Ensured that other self-transitions (e.g., Pending -> Pending) remain rejected to preserve state machine strictness, narrowing the scope of the idempotency to only Completed -> Completed.
• Improved Testing: Added new regression tests (test_completed_to_completed_is_idempotent, test_other_self_transitions_still_rejected) and updated an existing test (test_mark_completed_twice_is_idempotent) to thoroughly validate the fix and its narrow scope.
• Debug Logging: Incorporated tracing::debug! for the idempotent early-return path to provide better visibility and debugging information when a redundant Completed -> Completed transition occurs.

Changelog

• src/context/state.rs
  • Allowed Completed to Completed state transitions to be idempotent in the can_transition_to method.
  • Added an early return for idempotent state transitions in JobContext::transition_to with a debug log, preventing duplicate history entries.
  • Introduced test_completed_to_completed_is_idempotent to verify the idempotent behavior of the Completed state.
  • Added test_other_self_transitions_still_rejected to confirm that other self-transitions (e.g., Pending to Pending) are still rejected, ensuring the narrow scope of the fix.
• src/worker/job.rs
  • Renamed test_mark_completed_twice_returns_error to test_mark_completed_twice_is_idempotent to reflect the updated behavior.
  • Updated the test_mark_completed_twice_is_idempotent test to assert that mark_completed is idempotent and returns Ok when called multiple times for a completed job, rather than an error.

Activity

• This pull request supersedes and closes fix(jobs): make state transitions idempotent to prevent double-completion errors #731.
• It incorporates feedback from @zmanian on the previous attempt (fix(jobs): make state transitions idempotent to prevent double-completion errors #731), specifically regarding the scope of idempotency, the addition of debug logging, and comprehensive testing.
• The author has confirmed that cargo check, cargo test --lib context, and cargo clippy pass, with a manual test pending to trigger concurrent mark_completed calls.
• The PR description indicates it was generated with Claude Code.

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[gemini-code-assist]

Code Review

This pull request correctly addresses a race condition by making the Completed -> Completed state transition idempotent. The changes are well-tested and effectively solve the described issue. Overall, this is a solid fix.