rahul2393

feat(spanner): complete location-aware routing resilience and observability (#14418) ## Summary This change expands the location-aware routing path in the Spanner Go client with endpoint lifecycle management, stronger endpoint health handling, retry-aware exclusion, latency-aware replica selection, and route-selection tracing. ## What Changed - enabled location-aware routing automatically for experimental-host configurations while preserving env-var override behavior - added endpoint cache support for GetIfPresent, Evict, and DefaultChannel - switched endpoint health evaluation to real gRPC connectivity state, including transient-failure detection - added an endpoint lifecycle manager with: - background probing - idle eviction - endpoint recreation requests - recent transient-failure eviction tracking - integrated lifecycle handling into routing and affinity fallback paths - added request-id keyed one-shot endpoint exclusion for RESOURCE_EXHAUSTED retries - expanded skipped_tablet_uid reporting for transient failures and recent transient-failure evictions, with deduplication - added OpenTelemetry route-selection span attributes and events - updated focused tests and goldens for the new routing behavior ## Behavioral Notes - stopped or transient-failure endpoints are now treated differently from simply non-ready endpoints during tablet selection - retry attempts can avoid previously selected routed endpoints after RESOURCE_EXHAUSTED - leader-preferred requests still favor close leaders, but can fall back to a closer non-leader replica when the leader is too far away - route selection is now observable through tracing attributes and events

feat(spanner): add dynamic channel pool (#14611) Split of https://github.com/googleapis/google-cloud-go/pull/14604 Internal reference: go/go-dcp-design

chore(spanner): integrate location aware routing with RPCs (#13877) - Add `locationAwareSpannerClient` wrapper that intercepts RPCs and routes them to the server endpoint resolved by the existing `channelFinder`, falling back to the default gRPC channel when no endpoint is available - Add `endpointClientCache` that creates and caches per-address gRPC connections - Add transaction affinity tracking so Commit/Rollback route to the same server that handled the transaction, with read-only transactions routed independently per-request based on key ranges - Move request preparation (`prepareReadRequest`, etc.) and response observation (`observePartialResultSet`, etc.) from transaction/batch code into the client wrapper, keeping routing concerns in one place

chore(spanner): add routing hints and cache updates for begin/commit (#14252) ## Summary This change extends key-aware routing to include mutation-based `BeginTransaction` and `Commit` request payloads, and teaches the response path to consume `CacheUpdate` from `Transaction` and `CommitResponse`. ## What changed - Populate `RoutingHint` on `BeginTransaction` when a `mutationKey` is present - Populate `RoutingHint` on `Commit` from the first mutation in the request - Keep existing transaction-affinity routing for `Commit`/`Rollback` - Apply `CacheUpdate` from: - `Transaction` - `CommitResponse` - Add focused `KeyAwareChannel` tests for the new request/response behavior

fix(spanner): replace multiplexed session request loop with shared in-flight creation (#14215) Fixes: https://github.com/googleapis/google-cloud-go/issues/14212 Reworked multiplexed session initialization to use a shared in-flight creation latch instead of the old request goroutine and unbuffered channels. This fixes the startup deadlock triggered by a cancelled read-only transaction waiter and adds regression coverage for cancellation and client shutdown while session creation is in flight. sessionManager used an unbuffered multiplexedSessionReq channel and a single goroutine to coordinate multiplexed session creation. A cancelled waiter could cause that goroutine to return, leaving future callers blocked forever trying to send on the request channel during takeMultiplexed. Replace that request/ack flow with a shared in-flight creation record on sessionManager. When no multiplexed session exists, the manager starts one background creation with a manager-owned context and exposes a done channel for all waiters in that creation epoch. Waiters now block on done or their own context, and completion is broadcast by closing the shared channel. This removes the deadlock where one cancelled context could kill shared coordination, and it also lets Client.Close release any waiters blocked behind an in-flight initial create.

fix(spanner): guard rollback when aborted commit cleared session handle (#14218) Fixes: https://github.com/googleapis/google-cloud-go/issues/14025 Fix a panic in `ReadWriteTransaction.rollback` when a statement-based transaction commit is aborted, commit cleanup clears `t.sh`, and a later rollback is triggered after retry reset fails. ## Root cause `ReadWriteStmtBasedTransaction.CommitWithReturnResp` recycles the session handle and sets `t.sh = nil` even when commit returns `ABORTED`. If a caller then tries to retry with a canceled context, `ResetForRetry` fails before a new transaction is created. Cleanup paths can still call `Rollback` on the original transaction. `ReadWriteTransaction.rollback` dereferenced `t.sh` without checking whether the handle itself was nil, which caused a panic. ## Change - Snapshot `t.sh` inside `ReadWriteTransaction.rollback` - Return early if the session handle is nil - Use the local snapshot for `getID`, `getClient`, and `getMetadata` This keeps rollback a no-op when the session handle has already been cleaned up, which matches the intended behavior for an already-aborted transaction.

chore: librarian release pull request: 20260414T182932Z (#14432) PR created by the Librarian CLI to initialize a release. Merging this PR will auto trigger a release. Librarian Version: v0.10.1 Language Image: us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-prod/librarian-go@sha256:b04b076f5eedbb5546bd6fc1404969dd3698c8b19c0f34ae815a84ae735a606a <details><summary>spanner: v1.90.0</summary> ## [v1.90.0](https://github.com/googleapis/google-cloud-go/compare/spanner/v1.89.0...spanner/v1.90.0) (2026-04-14) ### Features * feat(spanner): add EnableDirectAccess field to ClientConfig (#14287) ([6adf5b7](https://github.com/googleapis/google-cloud-go/commit/6adf5b7)) * feat(spanner): Switch to using builtin open telemetry for EEF (#14193)([751febd](https://github.com/googleapis/google-cloud-go/commit/751febd)) * feat(spanner): complete location-aware routing resilience and observability (#14418 ) ([77aa4df](https://github.com/googleapis/google-cloud-go/commit/77aa4df)) ### Bug Fixes * fix(spanner): set gauge metric start time to match end time (#14289) ([e0760b5](https://github.com/googleapis/google-cloud-go/commit/e0760b5)) * fix(spanner): update DirectPath detection logic to use ALTS credentials(#14288)([3cd5716](https://github.com/googleapis/google-cloud-go/commit/3cd5716)) </details>

chore: librarian release pull request: 20260326T233413Z (#14270) PR created by the Librarian CLI to initialize a release. Merging this PR will auto trigger a release. Librarian Version: v0.8.4 Language Image: us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-prod/librarian-go@sha256:ac1efa3ad3c6d99efed878535b3a0fe63d0cce6701c335f03811d8b49004d652 <details><summary>spanner: v1.89.0</summary> ## [v1.89.0](https://github.com/googleapis/google-cloud-go/compare/spanner/v1.88.0...spanner/v1.89.0) (2026-03-26) ### Features * Add E2E fallback to the spanner client. (#13518) ([16af6a1c](https://github.com/googleapis/google-cloud-go/commit/16af6a1c)) * include cache updates and routing hint into BeginTransaction and Commit request/response respectively (PiperOrigin-RevId: 878019893) ([9c80b8b4](https://github.com/googleapis/google-cloud-go/commit/9c80b8b4)) * add SI, adapt, split point related proto (PiperOrigin-RevId: 871366927) ([d3eb851d](https://github.com/googleapis/google-cloud-go/commit/d3eb851d)) * Add gRPC A66/A94 metrics (#13825) ([d695802a](https://github.com/googleapis/google-cloud-go/commit/d695802a)) * support Scan from string to NullUUID (#14128) ([d897b6db](https://github.com/googleapis/google-cloud-go/commit/d897b6db)) ### Bug Fixes * replace multiplexed session request loop with shared in-flight creation (#14215) ([3e3bd2d3](https://github.com/googleapis/google-cloud-go/commit/3e3bd2d3)) * guard rollback when aborted commit cleared session handle (#14218) ([63151055](https://github.com/googleapis/google-cloud-go/commit/63151055)) ### Documentation * A comment for field `routing_hint` in messages `.google.spanner.v1.ResultSet` and `.google.spanner.v1.PartialResultSet` are changed (PiperOrigin-RevId: 878019893) ([9c80b8b4](https://github.com/googleapis/google-cloud-go/commit/9c80b8b4)) * A comment in message `.google.spanner.v1.TransactionOptions.ReadWrite.ReadLockMode` is changed (PiperOrigin-RevId: 878019893) ([9c80b8b4](https://github.com/googleapis/google-cloud-go/commit/9c80b8b4)) * A comment for message `ListCloudInstancesAction` is changed (PiperOrigin-RevId: 871366927) ([d3eb851d](https://github.com/googleapis/google-cloud-go/commit/d3eb851d)) * A comment for field `execution_options` in message `.google.spanner.executor.v1.StartTransactionAction` is changed (PiperOrigin-RevId: 871366927) ([d3eb851d](https://github.com/googleapis/google-cloud-go/commit/d3eb851d)) * A comment for message `TransactionExecutionOptions` is changed (PiperOrigin-RevId: 871366927) ([d3eb851d](https://github.com/googleapis/google-cloud-go/commit/d3eb851d)) </details>