[sdk-metrics] MetricPoint lookup perf tweaks

[CodeBlanch]

Changes

• Switch LookupAggregatorStore & LookupAggregatorStoreForDeltaWithReclaim to return a ref to the MetricPoint instead of the index to the MetricPoint. For cases where we created a MetricPoint, or reused one in the case of delta reclaim, this saves a second lookup/index/bounds-check into the array before the update is processed.

• Use MemoryMarshal.GetArrayDataReference on TFMs where it is supported to access the zero-tag MetricPoint (index 0) and the overflow MetricPoint (index 1) instead of performing a lookup/index/bounds-check on each measurement where they are used.

• Some renames to help with readability/clarity inside AggregatorStore...

  • LookupAggregatorStore -> LookupMetricPoint
  • LookupAggregatorStoreForDeltaWithReclaim -> LookupMetricPointForDeltaWithReclaim
  • Anything with "CustomTags" in the name now uses "WithTagFilerting" for example UpdateDoubleCustomTags -> UpdateDoubleWithTagFiltering

Benchmarks

TODO

Merge requirement checklist

• [X] CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 78.32168% with 31 lines in your changes missing coverage. Please review.

Project coverage is 86.12%. Comparing base (6250307) to head (678e3ce). Report is 332 commits behind head on main.

Files with missing lines	Patch %	Lines
src/OpenTelemetry/Metrics/AggregatorStore.cs	78.32%	31 Missing :warning:

Additional details and impacted files

[](https://app.codecov.io/gh/open-telemetry/opentelemetry-dotnet/pull/5869?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry) ```diff @@ Coverage Diff @@ ## main #5869 +/- ## ========================================== + Coverage 83.38% 86.12% +2.74% ========================================== Files 297 257 -40 Lines 12531 11209 -1322 ========================================== - Hits 10449 9654 -795 + Misses 2082 1555 -527 ``` | [Flag](https://app.codecov.io/gh/open-telemetry/opentelemetry-dotnet/pull/5869/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/open-telemetry/opentelemetry-dotnet/pull/5869/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry) | `?` | | | [unittests-Project-Experimental](https://app.codecov.io/gh/open-telemetry/opentelemetry-dotnet/pull/5869/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry) | `86.10% <78.32%> (?)` | | | [unittests-Project-Stable](https://app.codecov.io/gh/open-telemetry/opentelemetry-dotnet/pull/5869/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry) | `86.09% <78.32%> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files with missing lines](https://app.codecov.io/gh/open-telemetry/opentelemetry-dotnet/pull/5869?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry) | Coverage Δ | | |---|---|---| | [src/OpenTelemetry/Metrics/AggregatorStore.cs](https://app.codecov.io/gh/open-telemetry/opentelemetry-dotnet/pull/5869?src=pr&el=tree&filepath=src%2FOpenTelemetry%2FMetrics%2FAggregatorStore.cs&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry#diff-c3JjL09wZW5UZWxlbWV0cnkvTWV0cmljcy9BZ2dyZWdhdG9yU3RvcmUuY3M=) | `83.53% <78.32%> (+3.15%)` | :arrow_up: | ... and [232 files with indirect coverage changes](https://app.codecov.io/gh/open-telemetry/opentelemetry-dotnet/pull/5869/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry)