VladRodionov opened a new pull request, #8766:
URL: https://github.com/apache/hbase/pull/8766
## Summary
Migrates the native CacheAccessService path for AdaptiveLRU from
`LruAdaptiveBlockCache` to `LruCacheEngine` plus a dedicated adaptive
placement/admission policy.
The legacy `BlockCache` construction path remains unchanged.
## Changes
- Add `AdaptiveLruCachePlacementAdmissionPolicy`.
- Move AdaptiveLRU admission state and adjustment logic into the policy.
- Add eviction-pressure feedback to `CacheEvictionListener`.
- Add a default eviction-pressure callback to
`CachePlacementAdmissionPolicy`.
- Have `LruCacheEngine` report requested eviction pressure (`bytesToFree`).
- Have `TopologyBackedCacheAccessService` route:
- concrete block evictions to `CacheTopology`;
- eviction-pressure feedback to `CachePlacementAdmissionPolicy`.
- Use native `LruCacheEngine` for AdaptiveLRU in the CacheAccessService path.
- Preserve `LruAdaptiveBlockCache` for the legacy `BlockCacheFactory`
construction path.
## AdaptiveLRU behavior
The adaptive algorithm preserves the behavior of the legacy
`LruAdaptiveBlockCache`, including:
- the existing AdaptiveLRU configuration properties;
- the approximately 10-second evaluation window;
- requested eviction pressure rather than actual bytes freed;
- heavy-eviction count threshold;
- adaptive data-block admission percentage;
- deterministic block-offset filtering;
- recovery when eviction pressure decreases.
For tiered caches, AdaptiveLRU controls L1 admission only. It does not
globally reject a block that can still be placed in L2.
## Tests
Adds coverage for:
- AdaptiveLRU admission adjustment and recovery;
- single-tier data-block admission;
- inclusive and exclusive tier placement;
- eviction-pressure reporting by `LruCacheEngine`;
- eviction-pressure routing through `TopologyBackedCacheAccessService`;
- native AdaptiveLRU CacheAccessService construction;
- preservation of the legacy `LruAdaptiveBlockCache` construction path.
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