Mark SdkMeter as pub(crate)

[utpilla]

Changes

• SdkMeter should not be public

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.3%. Comparing base (8bd3294) to head (bc03ace).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2113     +/-   ##
=======================================
- Coverage   78.3%   78.3%   -0.1%     
=======================================
  Files        121     121             
  Lines      20815   20815             
=======================================
- Hits       16309   16308      -1     
- Misses      4506    4507      +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[TommyCpp]

This is a breaking change so maybe a change note?

[cijothomas]

This is a breaking change so maybe a change note?

+1. We also need to add one for #2085 too

[cijothomas]

Merging. Missing changelogs can be added in a follow up for both together.

[hdost]

Can i get a rational on this? Perhaps I am missing some context. Is it because users should use a builder and not the SdkMeter directly?

[cijothomas]

Can i get a rational on this? Perhaps I am missing some context. Is it because users should use a builder and not the SdkMeter directly?

From the examples:

let meter = global::meter("mylibraryname");

// OR
// let meter = meter_provider.meter("mylibraryname");

// Create a Counter Instrument from above meter
let counter = meter.u64_counter("my_counter").init();

SdkMeter not required to do this, and OTel's expectation is also rely on API only, not SDK constructs like SdkMeter, as that would tie their instrumentation to a specific SDK implementation (negating one of the original goals of OTel).

I also look at this from another angle - some pub thing was removed, and still all examples continue to compile, indicating that this should not have been public in the first place. Should work most of the time to help clean up public APIs to the absolute minimum required.