feat: support OpenTelemetry Metrics

[rachelyangdog]

Description

• adds support for OpenTelemetry Metrics

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.77%. Comparing base (12004d3) to head (fcc3fd4).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3487      +/-   ##
==========================================
- Coverage   61.88%   61.77%   -0.11%     
==========================================
  Files         142      142              
  Lines       12904    12904              
  Branches     1689     1689              
==========================================
- Hits         7986     7972      -14     
- Misses       4159     4172      +13     
- Partials      759      760       +1     

see 3 files with indirect coverage changes

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[pr-commenter]

Benchmarks [ tracer ]

Benchmark execution time: 2025-11-17 18:04:12

Comparing candidate commit fcc3fd4 in PR branch rachel.yang/otel-metrics-part2-telemetry with baseline commit 12004d3 in branch master.

Found 4 performance improvements and 13 performance regressions! Performance is the same for 176 metrics, 1 unstable metrics.

scenario:BM_TeaSapiSpindown

• 🟩 execution_time [-33.612µs; -14.131µs] or [-6.165%; -2.592%]

scenario:ContextPropagationBench/benchExtractHeaders128Bit-opcache

• 🟥 execution_time [+506.502ns; +544.165ns] or [+59.079%; +63.472%]

scenario:ContextPropagationBench/benchExtractHeaders64Bit-opcache

• 🟥 execution_time [+507.615ns; +562.385ns] or [+42.765%; +47.379%]

scenario:ContextPropagationBench/benchExtractTraceContext128Bit-opcache

• 🟥 execution_time [+505.903ns; +606.097ns] or [+27.376%; +32.797%]

scenario:MessagePackSerializationBench/benchMessagePackSerialization-opcache

• 🟥 execution_time [+5.997µs; +7.303µs] or [+5.702%; +6.944%]

scenario:PHPRedisBench/benchRedisOverhead-opcache

• 🟥 mem_peak [+48.632KB; +48.632KB] or [+2.019%; +2.019%]

scenario:SamplingRuleMatchingBench/benchGlobMatching1-opcache

• 🟩 execution_time [-200.196ns; -57.204ns] or [-8.324%; -2.379%]

scenario:SamplingRuleMatchingBench/benchRegexMatching1

• 🟥 execution_time [+30.959ns; +108.041ns] or [+2.584%; +9.019%]

scenario:SamplingRuleMatchingBench/benchRegexMatching2

• 🟥 execution_time [+107.105ns; +178.895ns] or [+9.139%; +15.264%]

scenario:SamplingRuleMatchingBench/benchRegexMatching2-opcache

• 🟩 execution_time [-84.488ns; -29.512ns] or [-6.415%; -2.241%]

scenario:SamplingRuleMatchingBench/benchRegexMatching3

• 🟥 execution_time [+80.706ns; +168.294ns] or [+6.795%; +14.170%]

scenario:SamplingRuleMatchingBench/benchRegexMatching3-opcache

• 🟥 execution_time [+49.995ns; +115.605ns] or [+3.961%; +9.160%]

scenario:SamplingRuleMatchingBench/benchRegexMatching4

• 🟥 execution_time [+73.213ns; +147.987ns] or [+6.229%; +12.591%]

scenario:SamplingRuleMatchingBench/benchRegexMatching4-opcache

• 🟥 execution_time [+101.123ns; +146.077ns] or [+8.203%; +11.849%]

scenario:SpanBench/benchOpenTelemetryAPI

• 🟥 mem_peak [+1.233MB; +1.266MB] or [+2.948%; +3.026%]

scenario:SpanBench/benchOpenTelemetryAPI-opcache

• 🟥 mem_peak [+1.585MB; +1.601MB] or [+4.105%; +4.147%]

scenario:TraceSerializationBench/benchSerializeTrace

• 🟩 execution_time [-30.788µs; -19.612µs] or [-6.898%; -4.394%]