fix(cache): add finalizer with BCL dispose pattern and thread safety docs#148
fix(cache): add finalizer with BCL dispose pattern and thread safety docs#148
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…docs Production code changes: - Add Dispose(bool disposing) pattern per BCL best practices - Add finalizer with try-catch and Debug.WriteLine for diagnostics - Only dispose managed resources from Dispose(), not finalizer - Add <threadsafety> XML documentation for thread safety guarantees - Add <remarks> documenting circular reference and disposal requirement Test additions: - ConcurrentDisposeAndTryGetValue_ShouldNotThrowOrCorrupt - ConcurrentDisposeAndSet_ShouldNotThrowOrCorrupt - DisposeDuringEvictionCallback_ShouldNotThrowOrDeadlock - DisposeDuringGetOrCreateFactory_ShouldNotCorruptState - MultipleConcurrentDisposeCalls_ShouldBeIdempotent - CounterOverflowBoundary_ValidatesBehaviorNearMaxValue - CounterAtMaxValue_Increment_WrapsToNegative Test fixes: - Reverted Assert.InRange to Assert.Equal for exact miss count assertion - Fixed overflow test comment to match dotnet/runtime#124140 math - Removed unused ManualResetEventSlim variables - Added using statements for ManualResetEventSlim disposal Ref: rjmurillo/ai-agents#1173 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Summary of ChangesHello @rjmurillo, 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 significantly enhances the Highlights
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Code Review
This pull request introduces a BCL-compliant dispose pattern with a finalizer to address a potential memory leak from a circular reference. It also adds valuable thread-safety documentation and a comprehensive suite of concurrency tests for disposal scenarios. The changes are well-structured and the new tests significantly improve the robustness of the class. However, I've found a critical issue in the new Dispose(bool) implementation where the logic to break the circular reference is incorrectly placed within the if (disposing) block, rendering the finalizer ineffective. This violates the rule that IDisposable objects must be properly disposed to prevent resource leaks. My review includes a detailed comment and a code suggestion to correct this.
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Pull request overview
This pull request implements a BCL-compliant dispose pattern with finalizer support for the MeteredMemoryCache class to properly handle circular references when the class owns its Meter instance. The changes add comprehensive thread-safety documentation, disposal race condition tests, and counter overflow boundary tests to ensure robust behavior under concurrent disposal scenarios and edge cases.
Changes:
- Added
Dispose(bool disposing)method following BCL best practices with proper managed/unmanaged resource separation - Introduced finalizer with try-catch wrapper to break circular references when
meterFactoryis null (the instance owns theMeter) - Added
<threadsafety>and<remarks>XML documentation explaining thread safety guarantees and circular reference concerns - Added 5 comprehensive concurrency tests covering disposal race conditions with read/write operations, eviction callbacks, and factory execution
- Added 2 counter overflow boundary tests to validate behavior near
long.MaxValue - Updated test comments for clarity on miss counting behavior
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
src/CacheImplementations/MeteredMemoryCache.cs |
Implements BCL dispose pattern with finalizer and enhanced thread-safety documentation |
tests/Integration/ConcurrencyTests.cs |
Adds 5 new tests for disposal thread-safety scenarios |
tests/Unit/MetricEmissionAccuracyTests.cs |
Adds 2 new overflow boundary tests using reflection to test counter wrap behavior |
tests/Unit/MeteredMemoryCacheTests.cs |
Updates comments to clarify hit/miss counting behavior in race condition test |
…r reference When meterFactory is null, MeteredMemoryCache creates and owns a Meter instance. This creates a circular reference: MeteredMemoryCache -> Meter -> Instruments -> Callbacks -> MeteredMemoryCache. The finalizer was introduced specifically to break this cycle when Dispose() is not called. However, _ownedMeter.Dispose() was moved inside the 'if (disposing)' block, causing the finalizer path (disposing=false) to skip meter disposal, leaving the circular reference intact. Fix: Move _ownedMeter.Dispose() outside the 'if (disposing)' block so it runs during both explicit disposal and finalization. Meter.Dispose() is safe to call during finalization as it only unregisters instruments (managed-only operation).
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Bugbot Autofix prepared fixes for 1 of the 1 bugs found in the latest run.
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- Drop Debug.WriteLine from finalizer catch (best-effort only) - Fix misleading Task.Yield comment (no timing guarantee) - Add reflection fragility comments to overflow tests
- TagBuilder: create FrozenDictionary snapshot to protect against concurrent modification of source dictionary - MeteredMemoryCache: add postcondition remarks to TryGetValue and CreateEntry documenting atomic counter guarantees Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Add 10 edge case tests covering: - Eviction callback re-entrance (add/remove during eviction) - CacheItemPriority-based eviction ordering - Meter disposed before cache scenarios - Rapid key overwrite statistics - Null value handling - Fresh cache statistics verification Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Accessing the Name property during finalization is unsafe because the string could be finalized already. Use GetHashCode():X8 instead for safe instance identification in error logging. Addresses review comment from Copilot on finalizer safety. Comment-ID: 2809682483 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Update "~146 billion" to "~146.2 billion ops/sec (~1.46 × 10^11 ops/sec)" for technical precision in documentation. Addresses review comment from Copilot. Comment-ID: 2809682469 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Summary
Dispose(bool disposing)method<threadsafety>XML documentation for thread safety guaranteesChanges
Production Code (
MeteredMemoryCache.cs)Dispose(bool disposing)per BCL best practicesmeterFactoryis nullDebug.WriteLinefor diagnostic traceability<threadsafety>and<remarks>XML docs with postconditionsProduction Code (
TagBuilder.cs)Test Additions (
ConcurrencyTests.cs)ConcurrentDisposeAndTryGetValue_ShouldNotThrowOrCorruptConcurrentDisposeAndSet_ShouldNotThrowOrCorruptDisposeDuringEvictionCallback_ShouldNotThrowOrDeadlockDisposeDuringGetOrCreateFactory_ShouldNotCorruptStateMultipleConcurrentDisposeCalls_ShouldBeIdempotentTest Additions (
MetricEmissionAccuracyTests.cs)CounterOverflowBoundary_ValidatesBehaviorNearMaxValueCounterAtMaxValue_Increment_WrapsToNegativeTest Additions (
EdgeCaseTests.cs) - NEWEvictionCallback_AddingItemsDuringEviction_ShouldNotCorruptStateEvictionCallback_RemovingItemsDuringEviction_ShouldNotCorruptStateCacheItemPriority_EvictionOrdering_LowerPriorityEvictedFirstCacheItemPriority_NeverRemove_SurvivesCompactMeterDisposedBeforeCache_ShouldNotThrowMeterDisposedDuringOperations_ShouldNotCorruptMeterFactoryDisposedBeforeCache_ShouldNotThrowRapidKeyOverwrite_ShouldMaintainCorrectStatisticsNullValue_ShouldBeHandledCorrectlyGetCurrentStatistics_OnFreshCache_ReturnsZerosTest Fixes
Assert.InRangetoAssert.Equal(0, missCount)for exact assertionManualResetEventSlimvariablesusingstatements for proper disposalTest plan
References
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