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fix(spanner): always prefer leader for strong reads and retries should only check EWMA score #12879

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fix(spanner): always prefer leader for strong reads and retries should only check EWMA score #12879

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48 changes: 27 additions & 21 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 @@ -813,43 +813,49 @@ 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(
TabletSnapshot preferredLeader =
preferLeader ? localLeaderForScoreBias(snapshot, hasDirectedReadOptions) : null;
boolean retryAfterInitialRequest = !skippedTabletUids.isEmpty();
boolean attemptedLeaderSelection = false;

if (preferLeader
&& !retryAfterInitialRequest
&& preferredLeader != null
&& preferredLeader.matches(directedReadOptions)) {
attemptedLeaderSelection = true;
selectionStats.sawMatchingReplica = true;
if (!shouldSkip(
snapshot,
preferLeader,
directedReadOptions,
preferredLeader,
hintBuilder,
excludedEndpoints,
skippedTabletUids,
skippedTabletDetails,
resolvedEndpoints,
selectionStats,
preferredLeader);
selectionStats)) {
return preferredLeader;
}
}

boolean checkedLeader = false;
if (preferLeader
&& !hasDirectedReadOptions
&& snapshot.hasLeader()
&& snapshot.leader().distance <= MAX_LOCAL_REPLICA_DISTANCE) {
checkedLeader = true;
selectionStats.sawMatchingReplica = true;
if (!shouldSkip(
if (!preferLeader
|| retryAfterInitialRequest
|| attemptedLeaderSelection
|| hintBuilder.getOperationUid() > 0L) {
return selectScoreAwareTablet(
snapshot,
snapshot.leader(),
preferLeader,
directedReadOptions,
hintBuilder,
excludedEndpoints,
skippedTabletUids,
skippedTabletDetails,
resolvedEndpoints,
selectionStats)) {
return snapshot.leader();
}
selectionStats,
preferredLeader);
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}

for (int index = 0; index < snapshot.tablets.size(); index++) {
if (checkedLeader && index == snapshot.leaderIndex) {
if (preferredLeader != null && index == snapshot.leaderIndex) {
continue;
}
TabletSnapshot tablet = snapshot.tablets.get(index);
Expand Down
66 changes: 65 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 @@ -693,7 +693,7 @@ public void preferLeaderFalseUsesLowestLatencyReplicaWhenScoresAvailable() {
}

@Test
public void preferLeaderTrueUsesLatencyScoresWhenOperationUidAvailable() {
public void preferLeaderTrueWithOperationUidStillPrefersReadyLeaderOnInitialRequest() {
FakeEndpointCache endpointCache = new FakeEndpointCache();
KeyRangeCache cache = new KeyRangeCache(endpointCache);
cache.useDeterministicRandom();
Expand All @@ -719,6 +719,70 @@ public void preferLeaderTrueUsesLatencyScoresWhenOperationUidAvailable() {
DirectedReadOptions.getDefaultInstance(),
hint);

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

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

endpointCache.get("server1");
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(200_000L));
EndpointLatencyRegistry.recordLatency(
null, TEST_OPERATION_UID, true, "server3", Duration.ofNanos(100_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,
"server1"::equals);

assertNotNull(server);
assertEquals("server3", server.getAddress());
}

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

endpointCache.get("server1");
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);
hint.addSkippedTabletUidBuilder().setTabletUid(1).setIncarnation(bytes("1"));
ChannelEndpoint server =
cache.fillRoutingHint(
true,
KeyRangeCache.RangeMode.COVERING_SPLIT,
DirectedReadOptions.getDefaultInstance(),
hint);

assertNotNull(server);
assertEquals("server2", server.getAddress());
}
Expand Down
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