[Backport 2.x] [Tiered Caching] Stats rework (1/3): Interfaces and implementations for individual tiers

[peteralfonsi]

Original PR: #12531

Signed-off-by: Peter Alfonsi [email protected]
Co-authored-by: Peter Alfonsi [email protected]
(cherry picked from commit cc22310)

Description

As part of tiered caching stats, changes the common ICache interface to use ICacheKey as its key. This key contains dimensions (for example, shard ID, index name, or tier) that can be used to aggregate stats. Also changes the CacheStats interface to store the necessary cache stats, and to support getting stats either as a total or aggregated by these dimensions.

Integrates these changes with OpenSearchOnHeapCache and EhcacheDiskCache. The stats implementation for the TieredSpilloverCache will be in a followup PR.

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Failing checks are inspected and point to the corresponding known issue(s) (See: Troubleshooting Failing Builds)
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)
• [N/A] Public documentation issue/PR created

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[github-actions]

❌ Gradle check result for 004c162: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

✅ Gradle check result for 235c954: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 92.70073% with 30 lines in your changes are missing coverage. Please review.

Project coverage is 71.26%. Comparing base (0dd892c) to head (235c954).
Report is 155 commits behind head on 2.x.

Files	Patch %	Lines
...in/java/org/opensearch/common/cache/ICacheKey.java	75.75%	3 Missing and 5 partials ⚠️
.../org/opensearch/common/cache/stats/CacheStats.java	87.50%	4 Missing and 3 partials ⚠️
...pensearch/common/cache/stats/CacheStatsHolder.java	95.32%	1 Missing and 4 partials ⚠️
.../opensearch/cache/store/disk/EhcacheDiskCache.java	93.75%	2 Missing and 1 partial ⚠️
...h/common/cache/serializer/ICacheKeySerializer.java	91.17%	3 Missing ⚠️
...search/cache/common/tier/TieredSpilloverCache.java	83.33%	1 Missing ⚠️
...search/common/cache/stats/ImmutableCacheStats.java	96.42%	0 Missing and 1 partial ⚠️
.../common/cache/stats/ImmutableCacheStatsHolder.java	96.55%	1 Missing ⚠️
...arch/common/cache/store/OpenSearchOnHeapCache.java	96.96%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x   #13247      +/-   ##
============================================
- Coverage     71.28%   71.26%   -0.02%     
- Complexity    60145    60715     +570     
============================================
  Files          4957     5010      +53     
  Lines        282799   285723    +2924     
  Branches      41409    41750     +341     
============================================
+ Hits         201591   203632    +2041     
- Misses        64189    64914     +725     
- Partials      17019    17177     +158     

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[sgup432]

@dblock @andrross @reta Can anyone of you approve/merge this?

[dblock]

@peteralfonsi @sgup432 Are there changes from the original PR? This area is way over my head, cc: @msfroh who merged the one to main.

[peteralfonsi]

@dblock No changes, this is the same as the original PR.

[sgup432]

@dblock Yeah these are from original PR which was already merged in main. Pinged you as we need help on approval/merge considering this is a backport PR.