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https://issues.apache.org/jira/browse/HBASE-30024?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vladimir Rodionov updated HBASE-30024:
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Summary: Add BlockCache-backed CacheEngine adapter for
TieredExclusiveTopology (was: Refactor CombinedBlockCache into explicit
TieredExclusiveTopology)
> Add BlockCache-backed CacheEngine adapter for TieredExclusiveTopology
> ---------------------------------------------------------------------
>
> Key: HBASE-30024
> URL: https://issues.apache.org/jira/browse/HBASE-30024
> Project: HBase
> Issue Type: New Feature
> Reporter: Vladimir Rodionov
> Assignee: Vladimir Rodionov
> Priority: Major
>
> h2. Description
> Refactor *CombinedBlockCache* by extracting its tier orchestration logic into
> an explicit *TieredExclusiveTopology* abstraction.
> CombinedBlockCache currently combines multiple responsibilities, including:
> * coordination between L1 (*LruBlockCache*) and L2 (*BucketCache*)
> * routing of block lookups across tiers
> * promotion of blocks from L2 to L1 on cache hit
> * aggregation of cache metrics
> This change separates these concerns by introducing *TieredExclusiveTopology*
> as a dedicated orchestration layer.
> h3. Scope
> * Introduce *TieredExclusiveTopology* implementing L1/L2 coordination
> * Move logic from CombinedBlockCache into the topology layer, including:
> ** lookup routing across tiers
> ** promotion/demotion behavior
> ** invalidation propagation
> ** metrics aggregation
> * Adapt CombinedBlockCache to:
> ** delegate to TieredExclusiveTopology, or
> ** act as a temporary compatibility wrapper
> h3. Notes
> * No behavior change intended — *TieredExclusiveTopology* should preserve
> current CombinedBlockCache semantics
> * Existing cache implementations (*LruBlockCache*, *BucketCache*) remain
> unchanged
> * This is a key step toward separating:
> ** topology (*CacheTopology*)
> ** storage (*CacheEngine*)
> ** policy (*CachePlacementPolicy*)
> * Lays groundwork for future support of alternative topologies (e.g.,
> inclusive mode)
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