perf: minor optimizations to the standard query path

README.md

@@ -50,7 +50,7 @@ If you are using Maven without the BOM, add this to your dependencies:
 If you are using Gradle 5.x or later, add this to your dependencies:
 
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:26.38.0')
+implementation platform('com.google.cloud:libraries-bom:26.39.0')
 
 implementation 'com.google.cloud:google-cloud-spanner'
 ```

google-cloud-spanner/src/main/java/com/google/cloud/spanner/AbstractReadContext.java

@@ -45,6 +45,7 @@
 import com.google.spanner.v1.DirectedReadOptions;
 import com.google.spanner.v1.ExecuteBatchDmlRequest;
 import com.google.spanner.v1.ExecuteSqlRequest;
+import com.google.spanner.v1.ExecuteSqlRequest.Builder;
 import com.google.spanner.v1.ExecuteSqlRequest.QueryMode;
 import com.google.spanner.v1.ExecuteSqlRequest.QueryOptions;
 import com.google.spanner.v1.PartialResultSet;
@@ -457,7 +458,7 @@ void initTransaction() {
 
   // A per-transaction sequence number used to identify this ExecuteSqlRequests. Required for DML,
   // ignored for query by the server.
-  private AtomicLong seqNo = new AtomicLong();
+  private final AtomicLong seqNo = new AtomicLong();
 
   // Allow up to 512MB to be buffered (assuming 1MB chunks). In practice, restart tokens are sent
   // much more frequently.
@@ -488,6 +489,10 @@ long getSeqNo() {
     return seqNo.incrementAndGet();
   }
 
+  protected boolean isReadOnly() {
+    return true;
+  }
+
   protected boolean isRouteToLeader() {
     return false;
   }
@@ -622,19 +627,18 @@ private ResultSet executeQueryInternal(
   @VisibleForTesting
   QueryOptions buildQueryOptions(QueryOptions requestOptions) {
     // Shortcut for the most common return value.
-    if (defaultQueryOptions.equals(QueryOptions.getDefaultInstance()) && requestOptions == null) {
-      return QueryOptions.getDefaultInstance();
+    if (requestOptions == null) {
+      return defaultQueryOptions;
     }
-    // Create a builder based on the default query options.
-    QueryOptions.Builder builder = defaultQueryOptions.toBuilder();
-    // Then overwrite with specific options for this query.
-    if (requestOptions != null) {
-      builder.mergeFrom(requestOptions);
-    }
-    return builder.build();
+    return defaultQueryOptions.toBuilder().mergeFrom(requestOptions).build();
   }
 
   RequestOptions buildRequestOptions(Options options) {
+    // Shortcut for the most common return value.
+    if (!(options.hasPriority() || options.hasTag() || getTransactionTag() != null)) {
+      return RequestOptions.getDefaultInstance();
+    }
+
     RequestOptions.Builder builder = RequestOptions.newBuilder();
     if (options.hasPriority()) {
       builder.setPriority(options.priority());
@@ -655,16 +659,7 @@ ExecuteSqlRequest.Builder getExecuteSqlRequestBuilder(
             .setSql(statement.getSql())
             .setQueryMode(queryMode)
             .setSession(session.getName());
-    Map<String, Value> stmtParameters = statement.getParameters();
-    if (!stmtParameters.isEmpty()) {
-      com.google.protobuf.Struct.Builder paramsBuilder = builder.getParamsBuilder();
-      for (Map.Entry<String, Value> param : stmtParameters.entrySet()) {
-        paramsBuilder.putFields(param.getKey(), Value.toProto(param.getValue()));
-        if (param.getValue() != null && param.getValue().getType() != null) {
-          builder.putParamTypes(param.getKey(), param.getValue().getType().toProto());
-        }
-      }
-    }
+    addParameters(builder, statement.getParameters());
     if (withTransactionSelector) {
       TransactionSelector selector = getTransactionSelector();
       if (selector != null) {
@@ -679,12 +674,26 @@ ExecuteSqlRequest.Builder getExecuteSqlRequestBuilder(
     } else if (defaultDirectedReadOptions != null) {
       builder.setDirectedReadOptions(defaultDirectedReadOptions);
     }
-    builder.setSeqno(getSeqNo());
+    if (!isReadOnly()) {
+      builder.setSeqno(getSeqNo());
+    }
     builder.setQueryOptions(buildQueryOptions(statement.getQueryOptions()));
     builder.setRequestOptions(buildRequestOptions(options));
     return builder;
   }
 
+  static void addParameters(ExecuteSqlRequest.Builder builder, Map<String, Value> stmtParameters) {
+    if (!stmtParameters.isEmpty()) {
+      com.google.protobuf.Struct.Builder paramsBuilder = builder.getParamsBuilder();
+      for (Map.Entry<String, Value> param : stmtParameters.entrySet()) {
+        paramsBuilder.putFields(param.getKey(), Value.toProto(param.getValue()));
+        if (param.getValue() != null && param.getValue().getType() != null) {
+          builder.putParamTypes(param.getKey(), param.getValue().getType().toProto());
+        }
+      }
+    }
+  }
+
   ExecuteBatchDmlRequest.Builder getExecuteBatchDmlRequestBuilder(
       Iterable<Statement> statements, Options options) {
     ExecuteBatchDmlRequest.Builder builder =

google-cloud-spanner/src/main/java/com/google/cloud/spanner/LatencyTest.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2021 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.cloud.spanner;
+
+import com.google.auth.oauth2.GoogleCredentials;
+import com.google.cloud.spanner.SpannerOptions.FixedCloseableExecutorProvider;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.ThreadLocalRandom;
+import org.threeten.bp.Duration;
+
+public class LatencyTest {
+
+  public static void main(String[] args) throws Exception {
+    ThreadFactory threadFactory =
+        ThreadFactoryUtil.tryCreateVirtualThreadFactory("spanner-async-worker");
+    if (threadFactory == null) {
+      return;
+    }
+    ScheduledExecutorService service = Executors.newScheduledThreadPool(0, threadFactory);
+    Spanner spanner =
+        SpannerOptions.newBuilder()
+            .setCredentials(
+                GoogleCredentials.fromStream(
+                    Files.newInputStream(
+                        Paths.get("/Users/loite/Downloads/appdev-soda-spanner-staging.json"))))
+            .setSessionPoolOption(
+                SessionPoolOptions.newBuilder()
+                    .setWaitForMinSessions(Duration.ofSeconds(5L))
+                    // .setUseMultiplexedSession(true)
+                    .build())
+            .setUseVirtualThreads(true)
+            .setAsyncExecutorProvider(FixedCloseableExecutorProvider.create(service))
+            .build()
+            .getService();
+    DatabaseClient client =
+        spanner.getDatabaseClient(
+            DatabaseId.of("appdev-soda-spanner-staging", "knut-test-ycsb", "latencytest"));
+    for (int i = 0; i < 1000000; i++) {
+      try (AsyncResultSet resultSet =
+          client
+              .singleUse()
+              .executeQueryAsync(
+                  Statement.newBuilder("select col_varchar from latency_test where col_bigint=$1")
+                      .bind("p1")
+                      .to(ThreadLocalRandom.current().nextLong(100000L))
+                      .build())) {
+        while (resultSet.next()) {
+          for (int col = 0; col < resultSet.getColumnCount(); col++) {
+            if (resultSet.getValue(col) == null) {
+              throw new IllegalStateException();
+            }
+          }
+        }
+      }
+    }
+  }
+}

google-cloud-spanner/src/main/java/com/google/cloud/spanner/PartitionedDmlTransaction.java

@@ -221,14 +221,6 @@ private ByteString initTransaction(final Options options) {
   private void setParameters(
       final ExecuteSqlRequest.Builder requestBuilder,
       final Map<String, Value> statementParameters) {
-    if (!statementParameters.isEmpty()) {
-      com.google.protobuf.Struct.Builder paramsBuilder = requestBuilder.getParamsBuilder();
-      for (Map.Entry<String, Value> param : statementParameters.entrySet()) {
-        paramsBuilder.putFields(param.getKey(), Value.toProto(param.getValue()));
-        if (param.getValue() != null && param.getValue().getType() != null) {
-          requestBuilder.putParamTypes(param.getKey(), param.getValue().getType().toProto());
-        }
-      }
-    }
+    AbstractReadContext.addParameters(requestBuilder, statementParameters);
   }
 }

google-cloud-spanner/src/main/java/com/google/cloud/spanner/ResumableStreamIterator.java

@@ -59,7 +59,7 @@ abstract class ResumableStreamIterator extends AbstractIterator<PartialResultSet
   private final RetrySettings streamingRetrySettings;
   private final Set<Code> retryableCodes;
   private static final Logger logger = Logger.getLogger(ResumableStreamIterator.class.getName());
-  private final BackOff backOff;
+  private BackOff backOff;
   private final LinkedList<PartialResultSet> buffer = new LinkedList<>();
   private final int maxBufferSize;
   private final ISpan span;
@@ -87,7 +87,6 @@ protected ResumableStreamIterator(
     this.span = tracer.spanBuilderWithExplicitParent(streamName, parent);
     this.streamingRetrySettings = Preconditions.checkNotNull(streamingRetrySettings);
     this.retryableCodes = Preconditions.checkNotNull(retryableCodes);
-    this.backOff = newBackOff();
   }
 
   private ExponentialBackOff newBackOff() {
@@ -252,7 +251,10 @@ protected PartialResultSet computeNext() {
             if (delay != -1) {
               backoffSleep(context, delay);
             } else {
-              backoffSleep(context, backOff);
+              if (this.backOff == null) {
+                this.backOff = newBackOff();
+              }
+              backoffSleep(context, this.backOff);
             }
           }
 

google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionImpl.java

@@ -99,6 +99,15 @@ interface SessionTransaction {
     void close();
   }
 
+  private static final Map<SpannerRpc.Option, ?>[] CHANNEL_HINT_OPTIONS =
+      new Map[SpannerOptions.MAX_CHANNELS];
+
+  static {
+    for (int i = 0; i < CHANNEL_HINT_OPTIONS.length; i++) {
+      CHANNEL_HINT_OPTIONS[i] = optionMap(SessionOption.channelHint(i));
+    }
+  }
+
   static final int NO_CHANNEL_HINT = -1;
 
   private final SpannerImpl spanner;
@@ -125,7 +134,7 @@ interface SessionTransaction {
     if (channelHint == NO_CHANNEL_HINT) {
       return sessionReference.getOptions();
     }
-    return optionMap(SessionOption.channelHint(channelHint));
+    return CHANNEL_HINT_OPTIONS[channelHint % CHANNEL_HINT_OPTIONS.length];
   }
 
   @Override

google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionPoolOptions.java

@@ -755,7 +755,7 @@ Builder setPoolMaintainerClock(Clock poolMaintainerClock) {
      * SessionPoolOptions#maxSessions} based on the traffic load. Failing to do so will result in
      * higher latencies.
      */
-    Builder setUseMultiplexedSession(boolean useMultiplexedSession) {
+    public Builder setUseMultiplexedSession(boolean useMultiplexedSession) {
       this.useMultiplexedSession = useMultiplexedSession;
       return this;
     }

google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java

@@ -99,7 +99,7 @@ public class SpannerOptions extends ServiceOptions<Spanner, SpannerOptions> {
       ImmutableSet.of(
           "https://www.googleapis.com/auth/spanner.admin",
           "https://www.googleapis.com/auth/spanner.data");
-  private static final int MAX_CHANNELS = 256;
+  static final int MAX_CHANNELS = 256;
   @VisibleForTesting static final int DEFAULT_CHANNELS = 4;
   // Set the default number of channels to GRPC_GCP_ENABLED_DEFAULT_CHANNELS when gRPC-GCP extension
   // is enabled, to make sure there are sufficient channels available to move the sessions to a

google-cloud-spanner/src/main/java/com/google/cloud/spanner/TransactionRunnerImpl.java

@@ -216,6 +216,11 @@ private TransactionContextImpl(Builder builder) {
               session.getOptions(), ThreadLocalRandom.current().nextLong(Long.MAX_VALUE));
     }
 
+    @Override
+    protected boolean isReadOnly() {
+      return false;
+    }
+
     @Override
     protected boolean isRouteToLeader() {
       return true;