feat: increase default number of channels when gRPC-GCP channel pool is enabled

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

@@ -74,6 +74,7 @@
 
 /** Options for the Cloud Spanner service. */
 public class SpannerOptions extends ServiceOptions<Spanner, SpannerOptions> {
+
   private static final long serialVersionUID = 2789571558532701170L;
   private static SpannerEnvironment environment = SpannerEnvironmentImpl.INSTANCE;
 
@@ -89,6 +90,8 @@ public class SpannerOptions extends ServiceOptions<Spanner, SpannerOptions> {
           "https://www.googleapis.com/auth/spanner.admin",
           "https://www.googleapis.com/auth/spanner.data");
   private static final int MAX_CHANNELS = 256;
+  private static final int DEFAULT_CHANNELS = 4;
+  @VisibleForTesting static final int GRPC_GCP_ENABLED_DEFAULT_CHANNELS = 8;
   private final TransportChannelProvider channelProvider;
 
   @SuppressWarnings("rawtypes")
@@ -133,6 +136,7 @@ public class SpannerOptions extends ServiceOptions<Spanner, SpannerOptions> {
    * {@link SpannerOptions}.
    */
   public interface CallCredentialsProvider {
+
     /** Return the {@link CallCredentials} to use for a gRPC call. */
     CallCredentials getCallCredentials();
   }
@@ -187,6 +191,7 @@ public interface CallCredentialsProvider {
    * }</pre>
    */
   public interface CallContextConfigurator {
+
     /**
      * Configure a {@link ApiCallContext} for a specific RPC call.
      *
@@ -307,6 +312,7 @@ static <ReqT, RespT> SpannerMethod valueOf(ReqT request, MethodDescriptor<ReqT,
    * }</pre>
    */
   public static class SpannerCallContextTimeoutConfigurator implements CallContextConfigurator {
+
     private Duration commitTimeout;
     private Duration rollbackTimeout;
 
@@ -453,6 +459,7 @@ public SpannerCallContextTimeoutConfigurator withPartitionReadTimeout(
 
   /** Default implementation of {@code SpannerFactory}. */
   private static class DefaultSpannerFactory implements SpannerFactory {
+
     private static final DefaultSpannerFactory INSTANCE = new DefaultSpannerFactory();
 
     @Override
@@ -463,6 +470,7 @@ public Spanner create(SpannerOptions serviceOptions) {
 
   /** Default implementation of {@code SpannerRpcFactory}. */
   private static class DefaultSpannerRpcFactory implements SpannerRpcFactory {
+
     private static final DefaultSpannerRpcFactory INSTANCE = new DefaultSpannerRpcFactory();
 
     @Override
@@ -475,6 +483,7 @@ public ServiceRpc create(SpannerOptions options) {
 
   /** {@link ExecutorProvider} that is used for {@link AsyncResultSet}. */
   public interface CloseableExecutorProvider extends ExecutorProvider, AutoCloseable {
+
     /** Overridden to suppress the throws declaration of the super interface. */
     @Override
     void close();
@@ -485,6 +494,7 @@ public interface CloseableExecutorProvider extends ExecutorProvider, AutoCloseab
    * ScheduledExecutorService}.
    */
   public static class FixedCloseableExecutorProvider implements CloseableExecutorProvider {
+
     private final ScheduledExecutorService executor;
 
     private FixedCloseableExecutorProvider(ScheduledExecutorService executor) {
@@ -602,6 +612,7 @@ private SpannerOptions(Builder builder) {
    * variables.
    */
   public interface SpannerEnvironment {
+
     /**
      * The optimizer version to use. Must return an empty string to indicate that no value has been
      * set.
@@ -624,6 +635,7 @@ default String getOptimizerStatisticsPackage() {
    * variables.
    */
   private static class SpannerEnvironmentImpl implements SpannerEnvironment {
+
     private static final SpannerEnvironmentImpl INSTANCE = new SpannerEnvironmentImpl();
     private static final String SPANNER_OPTIMIZER_VERSION_ENV_VAR = "SPANNER_OPTIMIZER_VERSION";
     private static final String SPANNER_OPTIMIZER_STATISTICS_PACKAGE_ENV_VAR =
@@ -646,6 +658,7 @@ public String getOptimizerStatisticsPackage() {
   /** Builder for {@link SpannerOptions} instances. */
   public static class Builder
       extends ServiceOptions.Builder<Spanner, SpannerOptions, SpannerOptions.Builder> {
+
     static final int DEFAULT_PREFETCH_CHUNKS = 4;
     static final QueryOptions DEFAULT_QUERY_OPTIONS = QueryOptions.getDefaultInstance();
     static final RetrySettings DEFAULT_ADMIN_REQUESTS_LIMIT_EXCEEDED_RETRY_SETTINGS =
@@ -669,8 +682,7 @@ public static class Builder
 
     private GrpcInterceptorProvider interceptorProvider;
 
-    /** By default, we create 4 channels per {@link SpannerOptions} */
-    private int numChannels = 4;
+    private Integer numChannels;
 
     private String transportChannelExecutorThreadNameFormat = "Cloud-Spanner-TransportChannel-%d";
 
@@ -1122,8 +1134,7 @@ public Builder setHost(String host) {
 
     /** Enables gRPC-GCP extension with the default settings. */
     public Builder enableGrpcGcpExtension() {
-      this.grpcGcpExtensionEnabled = true;
-      return this;
+      return this.enableGrpcGcpExtension(null);
     }
 
     /**
@@ -1133,6 +1144,11 @@ public Builder enableGrpcGcpExtension() {
     public Builder enableGrpcGcpExtension(GcpManagedChannelOptions options) {
       this.grpcGcpExtensionEnabled = true;
       this.grpcGcpOptions = options;
+      // By default, set number of channels to GRPC_GCP_ENABLED_DEFAULT_CHANNELS if gRPC-GCP
+      // extension is enabled
+      if (this.numChannels == null) {
+        this.numChannels = GRPC_GCP_ENABLED_DEFAULT_CHANNELS;
+      }
       return this;
     }
 
@@ -1166,6 +1182,11 @@ public SpannerOptions build() {
         // As we are using plain text, we should never send any credentials.
         this.setCredentials(NoCredentials.getInstance());
       }
+      // Set the number of channels to DEFAULT_CHANNELS if not set
+      if (this.numChannels == null) {
+        this.numChannels = DEFAULT_CHANNELS;
+      }
+
       return new SpannerOptions(this);
     }
   }

google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerOptionsTest.java

@@ -918,4 +918,38 @@ public void testCustomAsyncExecutorProvider() {
             .build();
     assertSame(service, options.getAsyncExecutorProvider().getExecutor());
   }
+
+  @Test
+  public void testDefaultNumChannelsWithGrpcGcpExtensionEnabled() {
+    SpannerOptions options =
+        SpannerOptions.newBuilder().setProjectId("test-project").enableGrpcGcpExtension().build();
+
+    assertEquals(options.getNumChannels(), SpannerOptions.GRPC_GCP_ENABLED_DEFAULT_CHANNELS);
+  }
+
+  @Test
+  public void testNumChannelsWithGrpcGcpExtensionEnabled() {
+    // Set number of channels explicitly, before enabling gRPC-GCP channel pool in SpannerOptions
+    // builder.
+    int numChannels = 5;
+    SpannerOptions options1 =
+        SpannerOptions.newBuilder()
+            .setProjectId("test-project")
+            .setNumChannels(numChannels)
+            .enableGrpcGcpExtension()
+            .build();
+
+    assertEquals(options1.getNumChannels(), numChannels);
+
+    // Set number of channels explicitly, after enabling gRPC-GCP channel pool in SpannerOptions
+    // builder.
+    SpannerOptions options2 =
+        SpannerOptions.newBuilder()
+            .setProjectId("test-project")
+            .enableGrpcGcpExtension()
+            .setNumChannels(numChannels)
+            .build();
+
+    assertEquals(options2.getNumChannels(), numChannels);
+  }
 }