perf: unroll first probe in ClassNameFilter.contains()#67
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perf: unroll first probe in ClassNameFilter.contains()#67
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Unroll the first hash probe out of the loop since it is the most common path (hit on first try). Also inline the rehash function in the collision loop to avoid method call overhead. Benchmark results (ClassNameFilterBenchmark, spring-web.jar dataset): Single-threaded: cacheSize=4096: 6.458 -> 6.166 us/op (-4.5%) cacheSize=65536: 6.654 -> 6.304 us/op (-5.3%) Multi-threaded (10 threads): cacheSize=4096: 12.006 -> 8.726 us/op (-27.3%) cacheSize=16384: 11.112 -> 9.327 us/op (-16.1%) cacheSize=65536: 10.865 -> 8.604 us/op (-20.8%) cacheSize=1048576:11.140 -> 8.695 us/op (-22.0%) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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What Does This Do
Unroll the first hash probe in
ClassNameFilter.contains()out of the loop, since it is the most common path (hit on first try). Also inline the rehash function in the collision loop to avoid method call overhead.Motivation
Benchmarking
ClassNameFilterBenchmarkagainst spring-web.jar showed significant multi-threaded improvement:Single-threaded:
Multi-threaded (10 threads):
The unrolled first probe avoids loop setup overhead and likely reduces contention in multi-threaded scenarios.
Additional Notes
contains()is changed;add()is unchangedContributor Checklist
Jira ticket: N/A — performance optimization, no ticket
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