chore: add fast crc32c concat implementation#3148
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BenWhitehead merged 1 commit intomainfrom Jun 24, 2025
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This new implementation provides a constant time computation regardless of the length of B, rather than the previous implementation which took linear time relative to the length of B. #### Benchmark summary CPU: AMD Ryzen Threadripper PRO 3945WX 12-Cores OS: Debian Testing ``` # JMH version: 1.37 # VM version: JDK 11.0.17, OpenJDK 64-Bit Server VM, 11.0.17+8 # VM invoker: /home/benwhitehead/opt/java/jdk-11.0.17+8/bin/java # VM options: -Xms1g -Xmx1g -XX:+AlwaysPreTouch # Blackhole mode: full + dont-inline hint (auto-detected, use -Djmh.blackhole.autoDetect=false to disable) # Warmup: 4 iterations, 30 s each # Measurement: 8 iterations, 30 s each # Timeout: 10 min per iteration # Threads: 1 thread, will synchronize iterations # Benchmark mode: Sampling time ``` ``` Benchmark (objectSize) Mode Cnt Score Error Units Crc32cBenchmark.concatCrc32c 131072 sample 9243752 0.074 ± 0.001 us/op Crc32cBenchmark.concatCrc32c 262144 sample 9015106 0.078 ± 0.001 us/op Crc32cBenchmark.concatCrc32c 524288 sample 9010257 0.074 ± 0.001 us/op Crc32cBenchmark.concatCrc32c 1048576 sample 9165519 0.074 ± 0.001 us/op Crc32cBenchmark.concatCrc32c 2097152 sample 8993038 0.075 ± 0.001 us/op Crc32cBenchmark.crc32cCombineGoogle 131072 sample 2070639 115.806 ± 0.018 us/op Crc32cBenchmark.crc32cCombineGoogle 262144 sample 1029209 233.019 ± 0.045 us/op Crc32cBenchmark.crc32cCombineGoogle 524288 sample 516517 464.360 ± 0.106 us/op Crc32cBenchmark.crc32cCombineGoogle 1048576 sample 262118 915.067 ± 0.354 us/op Crc32cBenchmark.crc32cCombineGoogle 2097152 sample 131385 1825.685 ± 0.834 us/op ```
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This new implementation provides a constant time computation regardless of the length of B, rather than the previous implementation which took linear time relative to the length of B.
Benchmark summary
CPU: AMD Ryzen Threadripper PRO 3945WX 12-Cores
OS: Debian Testing