perf: fast_regex: store literal needles in an Arc

[Omkar-Wagholikar]

re_or_saved_re() (src/sed/processor.rs:192) copies the regex for every input line. With an Arc<[u8]>, that copy shares the existing pattern instead of allocating a new one.

I have not added tests specifically for this change as there is not net behavior change only a perf update, and the existing tests cover the changes as well

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.85%. Comparing base (58608af) to head (2fc8b9d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #604   +/-   ##
=======================================
  Coverage   94.85%   94.85%           
=======================================
  Files          14       14           
  Lines        7230     7230           
  Branches      432      432           
=======================================
  Hits         6858     6858           
  Misses        371      371           
  Partials        1        1           

Flag	Coverage Δ
macos_latest	96.39% <100.00%> (ø)
ubuntu_latest	96.33% <100.00%> (ø)
windows_latest	0.00% <0.00%> (ø)

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[codspeed]

Merging this PR will regress 1 benchmark

⚠️ 1 benchmark spent significant time in system calls

System calls cannot be consistently instrumented, so they are not included in the measure, which understates the real cost. Please switch to the Walltime instrument to accurately measure system calls.

Measurement and system calls

• access_log_append

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 6 improved benchmarks
❌ 1 regressed benchmark
✅ 4 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	number_fix	1.2 s	1.3 s	-3.62%
⚡	remove_cr	502.9 ms	432.7 ms	+16.23%
⚡	access_log_no_del	1,042.8 ms	900 ms	+15.88%
⚡	access_log_no_subst	1,052.1 ms	908.8 ms	+15.77%
⚡	access_log_all_del	1,075 ms	932.2 ms	+15.33%
⚡	genome_subst	432.1 ms	389.9 ms	+10.83%
⚡	access_log_subst	2.2 s	2.2 s	+3.14%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing Omkar-Wagholikar:perf/literal-needle-arc (2fc8b9d) with main (58608af)}

[sylvestre]

Thanks for your PR