chore(profiling): clean up code and update Rust dependencies

[realFlowControl]

Description

This PR cleans up the profiler implementation and updates its direct Rust dependencies. It removes unused code and dependencies, reduces repeated test and build-script plumbing, and updates dependencies in focused commits.

The main runtime improvements are the upgrade to rustc-hash 2.1.3, which provides a faster and better-finalized hash algorithm with improved string hashing for stack interning, live heap tracking, and the I/O file descriptor cache, and the upgrade to rand 0.9.4 plus rand_distr 0.5.1, which uses the rewritten large-lambda Poisson sampler. In a local two-million-sample release benchmark, Poisson sampling improved from 121.44 ns to 33.23 ns at lambda 100 and from approximately 114 ns to 22 ns at the I/O and allocation lambdas, a 3.7–5.3x speedup. The Poisson state grows by 48 bytes per sampler, approximately 480 bytes per PHP thread (1 for NTS, n for ZTS).

The dynasmrt 5.0.0 update also picks up internal AArch64 instruction-cache handling and an upstream fix for an illegal-instruction crash on Apple AArch64, directly covering the generated PHP frameless-call trampolines.

Remaining updates are maintenance and compatibility upgrades; Criterion and UUID are intentionally unchanged because their latest versions would respectively conflict with criterion-perf-events and add another getrandom generation without improving profiler code.

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[datadog-datadog-us1-prod]

 

✨ Fix all issues with BitsAI

⚠️ Warnings

🚦 42 Pipeline jobs failed

DataDog/apm-reliability/dd-trace-php | test_web_custom: [8.0, fpm-fcgi]     

🧪 1 Test failed

All test failures are known flaky.

❄️ Known flaky: testInstrumentation from custom-framework-autoloading-test.DDTrace\Tests\Integrations\Custom\Autoloaded\InstrumentationTest  

DDTrace\Tests\Integrations\Custom\Autoloaded\InstrumentationTest::testInstrumentation
Failed asserting that an array has the key 'logs_created'.

tests/Integrations/Custom/Autoloaded/InstrumentationTest.php:80
tests/Common/RetryTraitVersionGeneric.php:28

Not introduced in this PR.

DataDog/apm-reliability/dd-trace-php | ASAN test_c with multiple observers: [8.3]     

DataDog/apm-reliability/dd-trace-php | test_extension_ci: [8.4]     

View all 42 failed jobs.

⌛ 3 Test performance regressions detected

testUserSignUp from symfony-52-test.DDTrace\Tests\Integrations\Symfony\V5_2\AutomatedLoginEventsTest — 8.02s (+7.47s, +1360%)  

testLoggedInCalls from symfony-52-test.DDTrace\Tests\Integrations\Symfony\V5_2\AutomatedLoginEventsTest — 1m 2.39s (+59.92s, +2419%)  

testLoggedInCalls from laravel-8x-test.DDTrace\Tests\Integrations\Laravel\V8_x\AutomatedLoginEventsTest — 11.8s (+11.11s, +1615%)  

ℹ️ Info

No other issues found (see more)

❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 54.08% (-0.04%)

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[pr-commenter]

Benchmarks [ profiler ]

Benchmark execution time: 2026-07-10 11:35:52

Comparing candidate commit f3f0c29 in PR branch florian/cleanup with baseline commit 50a327e in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 27 metrics, 9 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

• 🟩 = significantly better candidate vs. baseline
• 🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

[bwoebi]

Nice cleanup. I like the merging of zts+debug checks :-D