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Fix release and coverage CI failures
* ConflictSet.cpp: enable the interleaved read/write path whenever
  musttail is available, falling back to the default calling convention
  when preserve_none is not supported. This prevents a large block of
  compiled-but-dead code from being counted in coverage.

* CMakeLists.txt: detect which arch-specific hardening-check options the
  installed hardening-check binary supports, including the newer
  hyphenated spellings, so the release test no longer fails with an
  unknown option.

* .gitea/workflows/ci.yml: build the coverage job with
  -DUSE_SIMD_FALLBACK=ON so AVX512-only functions that cannot execute on
  the CI runners are not counted against line coverage.
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A data structure for optimistic concurrency control on ranges of bitwise-lexicographically-ordered keys.

Intended as an alternative to FoundationDB's skip list.

Hardware for all benchmarks is an AMD Ryzen 9 7900 with (2x32GB) 5600MT/s CL28-34-34-89 1.35V RAM.

$ clang++ --version

Ubuntu clang version 20.0.0 (++20241120082228+86734c857724-1~exp1~20241120202359.554)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-20/bin

Microbenchmark

Skip list

ns/op op/s err% ins/op cyc/op IPC bra/op miss% total benchmark
161.29 6,200,056.17 0.1% 3,014.03 831.04 3.627 504.59 0.0% 1.93 point reads
158.32 6,316,160.64 0.1% 2,954.16 815.80 3.621 490.17 0.0% 1.89 prefix reads
237.39 4,212,409.50 0.2% 3,592.41 1,233.96 2.911 629.31 0.0% 2.84 range reads
442.11 2,261,878.94 0.0% 4,450.57 2,314.25 1.923 707.92 2.1% 5.28 point writes
439.89 2,273,308.53 0.1% 4,410.22 2,302.29 1.916 694.74 2.1% 5.25 prefix writes
290.96 3,436,936.78 0.0% 2,315.38 1,528.68 1.515 396.69 3.3% 3.49 range writes
476.93 2,096,762.02 0.6% 6,999.33 2,484.94 2.817 1,251.73 1.3% 0.06 monotonic increasing point writes
131,736.57 7,590.91 1.1% 807,444.50 704,941.71 1.145 144,584.60 0.9% 0.01 worst case for radix tree
45.50 21,978,369.95 1.1% 902.00 232.36 3.882 132.00 0.0% 0.01 create and destroy

Radix tree (this implementation)

ns/op op/s err% ins/op cyc/op IPC bra/op miss% total benchmark
12.36 80,885,626.43 0.2% 243.56 63.62 3.828 31.07 0.6% 0.15 point reads
14.18 70,502,196.81 0.1% 297.72 73.13 4.071 40.31 0.5% 0.17 prefix reads
33.44 29,901,623.04 0.1% 767.90 172.42 4.454 101.32 0.2% 0.40 range reads
19.48 51,342,564.70 0.3% 374.45 100.43 3.728 48.92 0.5% 0.23 point writes
37.46 26,694,471.44 0.1% 672.00 193.14 3.479 101.28 0.3% 0.45 prefix writes
38.78 25,784,784.34 0.0% 738.26 199.93 3.693 111.59 0.1% 0.47 range writes
76.05 13,148,995.74 0.7% 1,450.77 397.16 3.653 275.72 0.0% 0.01 monotonic increasing point writes
286,920.33 3,485.29 0.4% 4,117,948.00 1,521,352.00 2.707 714,833.00 0.1% 0.01 worst case for radix tree
95.66 10,453,798.72 0.5% 1,986.00 495.04 4.012 315.00 0.0% 0.01 create and destroy

"Real data" test

Point queries only. Gc ratio is the ratio of time spent doing garbage collection to time spent adding writes or doing garbage collection. Lower is better.

skip list

Check: 4.53508 seconds, 371.81 MB/s, Add: 3.81222 seconds, 150.919 MB/s, Gc ratio: 33.66%, Peak idle memory: 5.61007e+06

radix tree

Check: 0.957735 seconds, 1760.6 MB/s, Add: 1.19942 seconds, 479.678 MB/s, Gc ratio: 38.6069%, Peak idle memory: 2.05667e+06

hash table

(The hash table implementation doesn't work on range queries, and its purpose is to provide an idea of how fast point queries can be)

Check: 0.804598 seconds, 2095.69 MB/s, Add: 0.671221 seconds, 857.147 MB/s, Gc ratio: 35.0034%, Peak idle memory: 0
S
Description
A data structure for optimistic concurrency control on ranges of bitwise-lexicographically-ordered keys.
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