refactor(sdk-metrics-base): meter shared states

[legendecas]

Which problem is this PR solving?

Refactors meter states so that we can safely add more meter internal fields like async instrument callback registrations.

Also hides the public Meter.collect method in the shared state interface so that it can only be exposed through MetricReader.

This is extracted from #2785 as part of the async callback re-work.

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• MeterSharedState.collect

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added

[codecov]

Codecov Report

Merging #2821 (03fa81f) into main (0213d82) will increase coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #2821      +/-   ##
==========================================
+ Coverage   93.25%   93.33%   +0.08%     
==========================================
  Files         152      165      +13     
  Lines        4904     5594     +690     
  Branches     1039     1176     +137     
==========================================
+ Hits         4573     5221     +648     
- Misses        331      373      +42     

Impacted Files	Coverage Δ
...ry-sdk-metrics-base/src/state/SyncMetricStorage.ts	78.94% <0.00%> (-21.06%)	⬇️
...y-sdk-metrics-base/src/state/AsyncMetricStorage.ts	85.18% <0.00%> (-14.82%)	⬇️
...metrics-base/src/state/MeterProviderSharedState.ts	100.00% <0.00%> (ø)
packages/exporter-trace-otlp-http/src/transform.ts	88.69% <0.00%> (ø)
...exporter-metrics-otlp-http/src/transformMetrics.ts	91.37% <0.00%> (ø)
...emetry-instrumentation-xml-http-request/src/xhr.ts	97.63% <0.00%> (ø)
...mentation-xml-http-request/src/enums/EventNames.ts	100.00% <0.00%> (ø)
...metrics-otlp-http/src/OTLPMetricExporterOptions.ts	100.00% <0.00%> (ø)
packages/exporter-trace-otlp-http/src/util.ts	100.00% <0.00%> (ø)
...s/exporter-trace-otlp-http/src/OTLPExporterBase.ts	100.00% <0.00%> (ø)
... and 7 more

[legendecas]

This was closed accidentally. Reopened, and rebased.

[pichlermarc]

Looks great! 🙂

[dyladan]

This looks mostly like a "pure" refactoring to me and no new functionality right? LGTM

[legendecas]

This looks mostly like a "pure" refactoring to me and no new functionality right?

Yeah, this PR doesn't introduce any new features.

[dyladan]

@open-telemetry/javascript-approvers please take a look at this if you have time

[seemk]

My moral support 🙂

[legendecas]

@open-telemetry/javascript-approvers this pr still needs one more review, I'd appreciate it if anyone can take a look at this :) I've updated it on top of the main branch and added a changelog entry.

[dyladan]

I'll bug everyone in the SIG meeting :)

[legendecas]

@open-telemetry/javascript-approvers merged the latest main branch and resolved conflicts. we still need one more review on this PR :)

[legendecas]

Unexpected push... reverted to the previous version 03fa81f.

We are still waiting for another review to merge :-)

[legendecas]

@vmarchaud thank you