address comments

Author: rahul2393

java-spanner/google-cloud-spanner/src/main/java/com/google/cloud/spanner/spi/v1/KeyAwareChannel.java

@@ -413,11 +413,6 @@ private static boolean shouldExcludeEndpointOnRetry(io.grpc.Status.Code statusCo
         || statusCode == io.grpc.Status.Code.UNAVAILABLE;
   }
 
-  private Predicate<String> consumeExcludedEndpointsForCurrentCall(
-      @Nullable String logicalRequestKey) {
-    return endpointOverloadCooldowns::isCoolingDown;
-  }
-
   @VisibleForTesting
   boolean isCoolingDown(String address) {
     return endpointOverloadCooldowns.isCoolingDown(address);
@@ -844,7 +839,7 @@ private void maybeTrackReadOnlyBegin(TransactionSelector selector) {
 
     private Predicate<String> excludedEndpoints() {
       if (excludedEndpoints == null) {
-        excludedEndpoints = parentChannel.consumeExcludedEndpointsForCurrentCall(logicalRequestKey);
+        excludedEndpoints = parentChannel.endpointOverloadCooldowns::isCoolingDown;
       }
       return excludedEndpoints;
     }

java-spanner/google-cloud-spanner/src/main/java/com/google/cloud/spanner/spi/v1/KeyRangeCache.java

@@ -18,6 +18,7 @@
 
 import com.google.api.core.InternalApi;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.Lists;
 import com.google.common.hash.Hashing;
 import com.google.protobuf.ByteString;
 import com.google.spanner.v1.CacheUpdate;
@@ -27,7 +28,6 @@
 import com.google.spanner.v1.RoutingHint;
 import com.google.spanner.v1.Tablet;
 import java.time.Duration;
-import java.util.AbstractList;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -740,7 +740,7 @@ RouteLookupResult lookupRoutingHint(
           directedReadOptions.getReplicasCase()
               != DirectedReadOptions.ReplicasCase.REPLICAS_NOT_SET;
       Map<String, ChannelEndpoint> resolvedEndpoints = new HashMap<>();
-      SelectionStats selectionStats = new SelectionStats();
+      SelectionState selectionStats = new SelectionState();
 
       TabletSnapshot selected =
           selectTablet(
@@ -812,7 +812,7 @@ private TabletSnapshot selectTablet(
         Set<Long> skippedTabletUids,
         List<SkippedTabletDetail> skippedTabletDetails,
         Map<String, ChannelEndpoint> resolvedEndpoints,
-        SelectionStats selectionStats) {
+        SelectionState selectionStats) {
       if (!preferLeader || hintBuilder.getOperationUid() > 0L) {
         TabletSnapshot preferredLeader =
             preferLeader ? localLeaderForScoreBias(snapshot, hasDirectedReadOptions) : null;
@@ -893,7 +893,7 @@ private TabletSnapshot selectScoreAwareTablet(
         Set<Long> skippedTabletUids,
         List<SkippedTabletDetail> skippedTabletDetails,
         Map<String, ChannelEndpoint> resolvedEndpoints,
-        SelectionStats selectionStats,
+        SelectionState selectionStats,
         @javax.annotation.Nullable TabletSnapshot preferredLeader) {
       long operationUid = hintBuilder.getOperationUid();
       List<EligibleReplica> eligibleReplicas =
@@ -924,7 +924,7 @@ private List<EligibleReplica> collectEligibleReplicas(
         Set<Long> skippedTabletUids,
         List<SkippedTabletDetail> skippedTabletDetails,
         Map<String, ChannelEndpoint> resolvedEndpoints,
-        SelectionStats selectionStats,
+        SelectionState selectionStats,
         long operationUid,
         boolean preferLeader,
         @javax.annotation.Nullable TabletSnapshot preferredLeader) {
@@ -991,17 +991,7 @@ private EligibleReplica lowestCostReplica(List<EligibleReplica> eligibleReplicas
     }
 
     private List<ChannelEndpoint> endpointView(List<EligibleReplica> eligibleReplicas) {
-      return new AbstractList<ChannelEndpoint>() {
-        @Override
-        public ChannelEndpoint get(int index) {
-          return eligibleReplicas.get(index).endpoint;
-        }
-
-        @Override
-        public int size() {
-          return eligibleReplicas.size();
-        }
-      };
+      return Lists.transform(eligibleReplicas, candidate -> candidate.endpoint);
     }
 
     private double selectionCostForEndpoint(
@@ -1109,7 +1099,7 @@ private boolean shouldSkip(
         Set<Long> skippedTabletUids,
         List<SkippedTabletDetail> skippedTabletDetails,
         Map<String, ChannelEndpoint> resolvedEndpoints,
-        SelectionStats selectionStats) {
+        SelectionState selectionStats) {
       String targetEndpointLabel = endpointLabel(snapshot, tablet);
       if (tablet.skip) {
         selectionStats.sawNonExcludedReplica = true;
@@ -1179,7 +1169,7 @@ private boolean shouldSkip(
       return true;
     }
 
-    private final class SelectionStats {
+    private final class SelectionState {
       private boolean sawMatchingReplica;
       private boolean sawExcludedReplica;
       private boolean sawNonExcludedReplica;

java-spanner/google-cloud-spanner/src/main/java/com/google/cloud/spanner/spi/v1/RequestIdTargetTracker.java

@@ -26,8 +26,13 @@
 final class RequestIdTargetTracker {
   @VisibleForTesting static final long MAX_TRACKED_TARGETS = 1_000_000L;
 
+  @VisibleForTesting
+  static final int TARGET_CACHE_CONCURRENCY =
+      Math.max(4, Runtime.getRuntime().availableProcessors());
+
   private static final Cache<String, RoutingTarget> TARGETS =
       CacheBuilder.newBuilder()
+          .concurrencyLevel(TARGET_CACHE_CONCURRENCY)
           .maximumSize(MAX_TRACKED_TARGETS)
           .expireAfterWrite(10, TimeUnit.MINUTES)
           .build();