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fix(spanner): prioritize leader replica for read-write transactions in location-aware routing #14195

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Merged
rahul2393 merged 1 commit into from
Sep 3, 2026
Merged

fix(spanner): prioritize leader replica for read-write transactions in location-aware routing #14195

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32 changes: 16 additions & 16 deletions ...ner/google-cloud-spanner/src/main/java/com/google/cloud/spanner/spi/v1/KeyRangeCache.java
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Original file line number Diff line number Diff line change
Expand Up @@ -936,22 +936,6 @@ private TabletSnapshot selectTablet(
List<SkippedTabletDetail> skippedTabletDetails,
Map<String, ChannelEndpoint> resolvedEndpoints,
SelectionState selectionStats) {
if (!preferLeader || hintBuilder.getOperationUid() > 0L) {
TabletSnapshot preferredLeader =
preferLeader ? localLeaderForScoreBias(snapshot, hasDirectedReadOptions) : null;
return selectScoreAwareTablet(
snapshot,
preferLeader,
directedReadOptions,
hintBuilder,
excludedEndpoints,
skippedTabletUids,
skippedTabletDetails,
resolvedEndpoints,
selectionStats,
preferredLeader);
}

boolean checkedLeader = false;
if (preferLeader
&& !hasDirectedReadOptions
Expand All @@ -971,6 +955,22 @@ private TabletSnapshot selectTablet(
return snapshot.leader();
}
}

if (!preferLeader || hintBuilder.getOperationUid() > 0L) {
TabletSnapshot preferredLeader =
preferLeader ? localLeaderForScoreBias(snapshot, hasDirectedReadOptions) : null;
return selectScoreAwareTablet(
snapshot,
preferLeader,
directedReadOptions,
hintBuilder,
excludedEndpoints,
skippedTabletUids,
skippedTabletDetails,
resolvedEndpoints,
selectionStats,
preferredLeader);
}
for (int index = 0; index < snapshot.tablets.size(); index++) {
if (checkedLeader && index == snapshot.leaderIndex) {
continue;
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34 changes: 33 additions & 1 deletion ...google-cloud-spanner/src/test/java/com/google/cloud/spanner/spi/v1/KeyRangeCacheTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -784,7 +784,7 @@ public void preferLeaderFalseUsesLowestLatencyReplicaWhenScoresAvailable() {
}

@Test
public void preferLeaderTrueUsesLatencyScoresWhenOperationUidAvailable() {
public void preferLeaderTrueWithOperationUidSelectsLeaderEvenWhenFollowerHasLowerLatency() {
FakeEndpointCache endpointCache = new FakeEndpointCache();
KeyRangeCache cache = new KeyRangeCache(endpointCache);
cache.useDeterministicRandom();
Expand All @@ -794,6 +794,38 @@ public void preferLeaderTrueUsesLatencyScoresWhenOperationUidAvailable() {
endpointCache.get("server2");
endpointCache.get("server3");

EndpointLatencyRegistry.recordLatency(
null, TEST_OPERATION_UID, true, "server1", Duration.ofNanos(300_000L));
EndpointLatencyRegistry.recordLatency(
null, TEST_OPERATION_UID, true, "server2", Duration.ofNanos(100_000L));
EndpointLatencyRegistry.recordLatency(
null, TEST_OPERATION_UID, true, "server3", Duration.ofNanos(200_000L));

RoutingHint.Builder hint =
RoutingHint.newBuilder().setKey(bytes("a")).setOperationUid(TEST_OPERATION_UID);
ChannelEndpoint server =
cache.fillRoutingHint(
true,
KeyRangeCache.RangeMode.COVERING_SPLIT,
DirectedReadOptions.getDefaultInstance(),
hint);

assertNotNull(server);
assertEquals("server1", server.getAddress());
}

@Test
public void preferLeaderTrueWithOperationUidFallsBackToScoreAwareWhenLeaderUnhealthy() {
FakeEndpointCache endpointCache = new FakeEndpointCache();
KeyRangeCache cache = new KeyRangeCache(endpointCache);
cache.useDeterministicRandom();
cache.addRanges(threeReplicaUpdate());

endpointCache.get("server1");
endpointCache.get("server2");
endpointCache.get("server3");
endpointCache.setState("server1", EndpointHealthState.TRANSIENT_FAILURE);

EndpointLatencyRegistry.recordLatency(
null, TEST_OPERATION_UID, true, "server1", Duration.ofNanos(300_000L));
EndpointLatencyRegistry.recordLatency(
Expand Down
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