test(storage): scope durable failpoints to the invoking thread

[DecisionNerd]

Closes #941.

Summary

• replace the process-global durable-intent test failpoint with thread-local one-shot state
• remove the poisonable shared test mutex
• deterministically prove an unrelated commit cannot steal the injected failure

Validation

• cargo fmt --all -- --check
• cargo test -p graphforge-storage --lib durable_rewrite::tests:: -- --test-threads=8 (10 passed)
• cargo test -p graphforge-storage --lib --no-fail-fast (659 passed, 2 ignored)
• bazelisk test //crates/graphforge-storage:graphforge_storage_test

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Summary by CodeRabbit

• Bug Fixes
  • Improved reliability of durable rewrite failure testing.
  • Ensured simulated failures remain isolated between threads and trigger only once.
  • Verified recovery and successful commits after a simulated failure.

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• crates/graphforge-storage/src/durable_rewrite.rs

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Walkthrough

The durable-rewrite test failpoint now uses a thread-local, one-shot flag. Tests no longer require a shared mutex. New coverage verifies thread isolation, recovery, and subsequent commit success.

Changes

Durable failpoint isolation

Layer / File(s)	Summary
Thread-local failpoint setup crates/graphforge-storage/src/durable_rewrite.rs	The test failpoint uses a thread-local Cell<bool> and resets after one use. Shared mutex handling was removed.
Isolation and recovery coverage crates/graphforge-storage/src/durable_rewrite.rs	A reusable staged rewrite helper supports tests for unrelated-thread commits, one-shot failure, durable-state recovery, and later rewrite success.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to acbfb

This localized test-only change scopes durable failpoints to the invoking thread and includes passing validation; no actionable merge-blocking risk remains beyond normal checks and review.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: durable failpoints are scoped to the invoking thread.
Description check	✅ Passed	The description states the problem, summarizes the implementation, links issue #941, and lists focused, full-suite, formatting, and Bazel validation. It omits several template checklists, but it provi…
Linked Issues check	✅ Passed	The changes satisfy issue #941. They use thread-local one-shot failpoints, remove the shared poisonable mutex, add deterministic thread-isolation and recovery coverage, preserve parallel execution, an…
Out of Scope Changes check	✅ Passed	The changes are limited to durable-rewrite test failpoint handling and regression coverage. They match issue #941 and do not include production durable-rewrite behavior, #931 implementation work, retr…

Full details: Description check

Explanation

The description states the problem, summarizes the implementation, links issue #941, and lists focused, full-suite, formatting, and Bazel validation. It omits several template checklists, but it provides the critical review information.

Full details: Linked Issues check

Explanation

The changes satisfy issue #941. They use thread-local one-shot failpoints, remove the shared poisonable mutex, add deterministic thread-isolation and recovery coverage, preserve parallel execution, and report all required test suites as passing.

Full details: Out of Scope Changes check

Explanation

The changes are limited to durable-rewrite test failpoint handling and regression coverage. They match issue #941 and do not include production durable-rewrite behavior, #931 implementation work, retries, or suite serialization.

✨ Finishing Touches 💡 1

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• Create stacked PR
• Commit on current branch

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• Create PR with unit tests
• Commit unit tests in branch fix/941-thread-local-rewrite-failpoint

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