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https://issues.apache.org/jira/browse/HBASE-30471?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vladimir Rodionov updated HBASE-30471:
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Summary: Remove LruBlockCache dependencies from test and production code
(was: Migrate LruBlockCache unit tests to LruCacheEngine)
> Remove LruBlockCache dependencies from test and production code
> ----------------------------------------------------------------
>
> Key: HBASE-30471
> URL: https://issues.apache.org/jira/browse/HBASE-30471
> Project: HBase
> Issue Type: New Feature
> Components: BlockCache
> Affects Versions: 4.0.0-alpha-1
> Reporter: Vladimir Rodionov
> Assignee: Vladimir Rodionov
> Priority: Major
>
> h2. Description
> {{LruBlockCache}} was migrated to the new pluggable cache architecture as
> {{LruCacheEngine}} in HBASE-30104.
> The implementation migration intentionally preserved most of the existing LRU
> cache behavior and
> algorithm, but the legacy {{LruBlockCache}} unit-test suite was not migrated
> at the same time.
> As a result, a significant part of the behavioral coverage still exercises
> the legacy
> {{BlockCache}} implementation rather than the native {{CacheEngine}}
> implementation.
> This change should migrate the relevant {{LruBlockCache}} unit tests to
> {{LruCacheEngine}} and
> reassign tests whose behavior now belongs to higher-level cache abstractions.
> The goal is to preserve behavioral coverage, not to mechanically copy every
> legacy test.
> h2. Scope
> * Identify existing {{LruBlockCache}} tests that verify behavior now owned by
> {{LruCacheEngine}}.
> * Migrate those tests to exercise {{LruCacheEngine}} directly.
> * Preserve coverage for:
> ** cache insertion;
> ** cache lookup and hit/miss behavior;
> ** explicit eviction;
> ** capacity-driven eviction;
> ** LRU ordering;
> ** SINGLE/MULTI/MEMORY priority behavior;
> ** cache size and element accounting;
> ** block-type accounting;
> ** reference-count handling;
> ** runtime resizing;
> ** configuration change handling;
> ** eviction listener notification;
> ** shutdown behavior;
> ** cache statistics.
> * Reuse existing test data and helpers where practical.
> * Remove or consolidate duplicate tests where equivalent {{LruCacheEngine}}
> coverage already
> exists.
> h2. Responsibility Changes
> Not all legacy {{LruBlockCache}} tests should be moved directly to
> {{LruCacheEngine}}.
> The new architecture separates local cache-engine behavior from topology and
> orchestration.
> Tests for behavior such as:
> * victim-cache relationships;
> * {{setVictimCache()}};
> * promotion or demotion between cache tiers;
> * {{CombinedBlockCache}} assumptions;
> * cross-cache orchestration;
> do not belong to {{LruCacheEngine}} and should instead remain temporarily as
> legacy compatibility
> tests or be migrated to the appropriate {{CacheTopology}} /
> {{CacheAccessService}} test suite.
> The intended mapping is:
> {code}
> Legacy LruBlockCache test New test owner
> local LRU storage behavior -> LruCacheEngine
> capacity and local eviction -> LruCacheEngine
> reference counting -> LruCacheEngine
> size/accounting/statistics -> LruCacheEngine
> dynamic resizing -> LruCacheEngine
> configuration updates -> LruCacheEngine
> eviction notifications -> LruCacheEngine
> victim-cache behavior -> CacheTopology / CacheAccessService
> combined-cache behavior -> CacheTopology / CacheAccessService
> cross-tier promotion/demotion -> CacheTopology / CacheAccessService
> legacy BlockCache compatibility -> legacy compatibility tests
> {code}
> * Direct LRU implementation tests are migrated to {{LruCacheEngine}} where
> possible.
> * Tests that depend on RegionServer ownership of {{BlockCache}} remain
> unchanged until
> RegionServer cache ownership is migrated to {{CacheAccessService}}.
> * No attempt is made in this ticket to remove all legacy {{BlockCache}} test
> usage.
> *
> h2. Motivation
> {{LruCacheEngine}} is becoming the reusable native LRU engine for the
> pluggable cache architecture
> and may also be used as the storage engine for higher-level cache variants
> such as IndexOnlyLRU
> and AdaptiveLRU.
> Keeping most behavioral coverage attached only to {{LruBlockCache}} makes
> future cache-engine
> changes less safe and leaves the native implementation under-tested.
> Migrating the relevant tests establishes {{LruCacheEngine}} as the primary
> implementation under
> test while keeping topology and compatibility concerns in their appropriate
> architectural layers.
> h2. Acceptance Criteria
> * Core LRU cache behavior is tested directly through {{LruCacheEngine}}.
> * Existing behavioral coverage is preserved unless a test is obsolete or
> duplicated.
> * Tests for topology/orchestration behavior are not incorrectly moved into
> the engine test suite.
> * Legacy compatibility tests remain only where they still validate supported
> legacy behavior.
> * The migrated tests pass without depending on {{LruBlockCache}}-specific
> APIs that are not part
> of {{CacheEngine}} behavior.
> * No production behavior changes are introduced by this ticket.
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