HBASE-30329 Add topology-backed cache diagnostics - #8575
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Pull request overview
Routes legacy block caches and diagnostics through the topology-backed cache framework.
Changes:
- Adds single-tier and inclusive topology-backed cache support.
- Adds aggregated cached-block iteration diagnostics.
- Migrates compatibility helpers and tests to topology-backed services.
Reviewed changes
Copilot reviewed 15 out of 15 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
TestCacheOnWrite.java |
Uses topology-aware cache unwrapping. |
TestCacheConfig.java |
Verifies topology-backed configuration. |
TestSingleTierTopologyBackedCacheAccessService.java |
Tests single-tier behavior. |
TestInclusiveCombinedBlockCacheCompatibleTopologyBackedCacheAccessService.java |
Tests inclusive topology semantics. |
TestCacheAccessServices.java |
Updates factory expectations. |
TestBlockCacheBackedCacheAccessService.java |
Removes legacy adapter tests. |
CacheAccessServiceTestFactory.java |
Unwraps topology-backed caches. |
CacheConfig.java |
Preserves single-tier legacy cache access. |
TopologyBackedCacheAccessServices.java |
Adds single-tier and inclusive factories. |
TopologyBackedCacheAccessService.java |
Adds single-tier writes and block iteration. |
SingleTierTopology.java |
Defines the single-tier topology. |
SingleEngineTopology.java |
Renames its topology type. |
DefaultHBaseCachePlacementAdmissionPolicy.java |
Updates single-tier policy handling. |
CacheTopologyType.java |
Introduces SINGLE_TIER. |
CacheAccessServices.java |
Routes all cache variants by topology. |
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| return TopologyBackedCacheAccessServices.fromSingleBlockCache("single", blockCache, | ||
| DefaultHBaseCachePlacementAdmissionPolicy.INSTANCE); |
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| BlockCache[] blockCaches = combinedBlockCache.getBlockCaches(); | ||
| if (blockCaches.length != 2) { | ||
| throw new IllegalArgumentException( | ||
| "InclusiveCombinedBlockCache must expose exactly two block caches"); | ||
| } | ||
|
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| return fromTieredInclusiveBlockCaches("inclusive-combined", blockCaches[0], blockCaches[1], | ||
| DefaultHBaseCachePlacementAdmissionPolicy.INSTANCE); |
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| Optional<CacheEngine> engine = topology.getEngine(CacheTier.L1); | ||
| if (!engine.isPresent()) { | ||
| return; | ||
| } |
taklwu
requested changes
Aug 28, 2026
taklwu
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taklwu
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actually we get more than just topology-backed cache diagnostics , the single-tier caches refactoring. maybe call the title as Add topology-backed cache diagnostics and migrate single tier cache
| * </p> | ||
| */ | ||
| @InterfaceAudience.Private | ||
| public class SingleEngineTopology implements CacheTopology { |
Contributor
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will this SingleEngineTopology use with SingleTierTopology ? or how does it work in the upcoming/next JIRA?
mainly I found no usage about this SingleEngineTopology
| * assertions, cached-block iteration, metrics inspection, or other diagnostic checks. | ||
| * </p> | ||
| * <p> | ||
| * Only {@link BlockCacheBackedCacheAccessService} is supported. Services backed by future |
Contributor
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it seems this line of comment is no longer valid that we're using TopologyBackedCacheAccessServices, can you update the comment of blockCache?
| */ | ||
| if (topologyView.getType() == CacheTopologyType.SINGLE) { | ||
| if (topologyView.getType() == CacheTopologyType.SINGLE_TIER) { | ||
| return TierDecision.single(CacheTier.SINGLE); |
Contributor
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I'm wondered if CacheTier.SINGLE should be removed and only keep L1 and L2? but let me know if my understanding is incorrect.
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Summary
This PR extends the topology-backed cache access framework so that cache diagnostics and cache
access are consistently routed through
TopologyBackedCacheAccessService.The main change is that plain single-tier
BlockCacheimplementations now use the sametopology-backed access path as combined caches. Single-tier caches are represented by
SingleTierTopology, while existing two-tier cache variants continue to use topology-specificrepresentations:
BlockCache->SingleTierTopologyCombinedBlockCache->TieredExclusiveTopologyInclusiveCombinedBlockCache->TieredInclusiveTopologyThis keeps the legacy cache implementations underneath through
BlockCacheBackedCacheEngine, butmoves the access-service boundary to the topology/cache-engine model.
Motivation
After HBASE-30305, exclusive combined-cache orchestration was moved behind
TopologyBackedCacheAccessService. Follow-up testing showed that diagnostic and compatibility pathsstill had assumptions about
BlockCacheBackedCacheAccessServiceand concreteBlockCacheimplementations.
This PR removes those assumptions from the main factory path by making topology-backed access the
normal path for both single-tier and combined caches.
Changes
SingleTierTopology.CacheTopologyType.SINGLE_TIER.BlockCacheinstances.InclusiveCombinedBlockCache.cacheBlock(key, block)behavior for single-tier caches.BlockCacheinstances from topology-backed serviceswhere tests still need direct compatibility checks.
Compatibility notes
BlockCacheBackedCacheAccessServiceis no longer the default factory result for plain block caches.Instead, the main factory now returns a
TopologyBackedCacheAccessServicebacked bySingleTierTopology.The underlying legacy
BlockCacheimplementations are still preserved throughBlockCacheBackedCacheEngine. This PR does not migrateLruBlockCache,BucketCache, or otherconcrete cache implementations to native
CacheEngineimplementations yet. That remains a follow-upmigration step.
Testing
Focused tests: