[darkraider01]

Fixes #3714

Changes

• Baseline retention & eviction: Replaced the raw cached value in PrecomputedSum::reported with BaselineEntry<T> tracking last_value and consecutive missed_count.
  • Increments missed_count at the start of each collection cycle.
  • Resets missed_count to 0 whenever an attribute set has an accepted observation.
  • Retains the baseline through exactly one missed collection cycle so temporary gaps do not reset delta calculation.
  • Evicts the baseline after two consecutive missed collection cycles to keep memory bounded.
• Non-finite rejection: Filter out NaN and infinite values upfront in Measure::call and BoundPrecomputedSumHandle::call, preventing invalid measurements from being recorded and treating those cycles as missed collections.
• Tests:
  • Updated observable_counter_delta_attribute_set_reappears_after_gap to expect delta 30 (80 - 50) on reappearance after 1 missed cycle.
  • Added unit test delta_rejects_nan_and_retains_baseline for f64 NaN rejection and baseline preservation.
  • Added unit test delta_evicts_baseline_after_two_consecutive_missed_collections.
  • Added integration tests observable_counter_delta_stale_eviction and observable_counter_delta_f64_nan_rejection.
• Documentation: Added entry in opentelemetry-sdk/CHANGELOG.md under ## vNext.

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

❌ Patch coverage is 93.43066% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.1%. Comparing base (7ed5d1b) to head (04b2079).
⚠️ Report is 46 commits behind head on main.

Files with missing lines	Patch %	Lines
...emetry-sdk/src/metrics/internal/precomputed_sum.rs	92.6%	5 Missing ⚠️
opentelemetry-sdk/src/metrics/mod.rs	94.2%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #3720     +/-   ##
=======================================
- Coverage   83.2%   83.1%   -0.1%     
=======================================
  Files        131     130      -1     
  Lines      29598   29415    -183     
=======================================
- Hits       24630   24455    -175     
+ Misses      4968    4960      -8     

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[cijothomas]

I’d prefer to wait for clarification in [specification(https://github.com/open-telemetry/opentelemetry-specification/issues/4861) before changing this behavior. The proposed one-cycle retention policy is not currently defined by the specification and its better to get a spec blessing to ensure consistency.

[darkraider01]

Alright ! I'll fold it into draft PR until then

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Waiting on the author · refreshed 2026-10-26 20:04 UTC

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