Fix PooledHashMap dropping live entries when an entry is removed during forEach

[abdessattar23]

Noticed PooledHashMap.forEach can skip an entry if the callback removes the one it's currently on. It walks each bucket by index, so remove() shifts the next entry into the current slot and i++ jumps over it

This bites AsynchronousMetricStorage in REUSABLE_DATA mode: during collection it removes stale series while iterating, so a live series sharing a bucket with a stale one can get dropped from that cycle. For cumulative async that shows up as a gap then a jump in the output. (IMMUTABLE_DATA uses ConcurrentHashMap and was fine. The code comment even says the map was picked to allow removal during iteration, it just wasn't holding up)

Fix: iterate each bucket back-to-front so removing the current entry only shifts already-visited ones. Added tests at the map level (collision plus remove-while-iterating) and the storage level (live series survive when stale ones drop)

[linux-foundation-easycla]

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• ✅ login: abdessattar23 / name: Mohammed Abdessetar Elyagoubi (dae39c2)

[jack-berg]

Nice catch. Build is failing because of formatting. Please run ./gradlew spotlessApply, and commit / push the changes.

[jack-berg]

This test relies on the default capacity changing. Can you either add a comment indicating that if the default capacity changes this test will have to change, or use a different key type that uses a constant hashcode such that keys are guaranteed to be in the same bucket?

[abdessattar23]

Done, thanks. Used a constant-hashcode key so the collision doesn't depend on capacity anymore

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.50%. Comparing base (824334c) to head (d94ae0c).
⚠️ Report is 14 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8499      +/-   ##
============================================
- Coverage     78.77%   78.50%   -0.27%     
- Complexity     8579     8601      +22     
============================================
  Files          1009     1013       +4     
  Lines         28993    29150     +157     
  Branches       3599     3632      +33     
============================================
+ Hits          22839    22885      +46     
- Misses         5311     5421     +110     
- Partials        843      844       +1     

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[abdessattar23]

@jack-berg Now all jobs are succeeding and tests too, I believe it's ready now :)

[jack-berg]

Thanks!

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