Vladimir Rodionov created HBASE-30471:
-----------------------------------------
Summary: Migrate LruBlockCache unit tests to LruCacheEngine
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
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}
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.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
