[Cosmos] Port hub region caching per partition level (#48788)#48789
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jeet1995 wants to merge 1 commit intoAzure:mainfrom
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[Cosmos] Port hub region caching per partition level (#48788)#48789jeet1995 wants to merge 1 commit intoAzure:mainfrom
jeet1995 wants to merge 1 commit intoAzure:mainfrom
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Port hub region caching from .NET SDK (PR Azure#5648) to Java SDK. Feature summary: - After 2 consecutive 404/1002 (ReadSessionNotAvailable) on single-master accounts, SDK sets x-ms-cosmos-hub-region-processing-only header - Non-hub regions return 403/3 (WriteForbidden); SDK retries to next region - Hub region responds with 200 OK; SDK caches hub URI for that partition - Future requests route directly to cached hub (warm path) - Works for both PPAF and non-PPAF accounts Implementation details: - Feature flag: COSMOS.HUB_REGION_PROCESSING_ENABLED (default: false) - New class: GlobalPartitionEndpointManagerForHubRegionRouting - Per-partition ConcurrentHashMap cache for hub region URIs - Warm/cold path routing, cache invalidation, thread-safe - ClientRetryPolicy: 403/3 handling on read path for hub discovery - ClientRetryPolicy: Hub header gated behind feature flag - ClientRetryPolicy.onBeforeSendRequest: Warm path cache check - RxDocumentClientImpl: Cache hub on successful response - 13 unit tests covering all cache operations and eligibility Files changed: - Configs.java: Add feature flag constants and getter - ClientRetryPolicy.java: Hub header gating, 403/3 read path, warm path - RetryPolicy.java: Wire hub region manager - RxDocumentClientImpl.java: Instantiate manager, cache on success - GlobalPartitionEndpointManagerForHubRegionRouting.java (new) - 5 test files updated for new constructor parameter Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Issue
Fixes #48788
Description
Ports the per-partition hub region caching feature from .NET SDK (PR Azure/azure-cosmos-dotnet-v3#5648) to the Java SDK.
Problem
On single-master accounts, repeated 404/1002 (ReadSessionNotAvailable) errors cause unnecessary retries without discovering the hub region. No caching exists, so every request repeats the full discovery chain.
Solution
Feature Flag
Gated behind COSMOS.HUB_REGION_PROCESSING_ENABLED (env var: COSMOS_HUB_REGION_PROCESSING_ENABLED). Disabled by default per Debdatta Kunda's guidance.
Key Changes
Testing