Added API for accessing channel logger on NameResolver.Args.

api/src/main/java/io/grpc/NameResolver.java

@@ -408,22 +408,39 @@ public ConfigOrError parseServiceConfig(Map<String, ?> rawServiceConfig) {
    */
   @ExperimentalApi("https://github.com/grpc/grpc-java/issues/1770")
   public static final class Args {
+    private static final ChannelLogger NOOP_CHANNEL_LOGGER = new ChannelLogger() {
+      @Override
+      public void log(ChannelLogLevel level, String message) {
+      }
+
+      @Override
+      public void log(ChannelLogLevel level, String messageFormat, Object... args) {
+      }
+    };
+
     private final int defaultPort;
     private final ProxyDetector proxyDetector;
     private final SynchronizationContext syncContext;
     private final ServiceConfigParser serviceConfigParser;
+    private final ChannelLogger channelLogger;
     @Nullable private final Executor executor;
 
     Args(
         Integer defaultPort,
         ProxyDetector proxyDetector,
         SynchronizationContext syncContext,
         ServiceConfigParser serviceConfigParser,
+        @Nullable ChannelLogger channelLogger,
         @Nullable Executor executor) {
       this.defaultPort = checkNotNull(defaultPort, "defaultPort not set");
       this.proxyDetector = checkNotNull(proxyDetector, "proxyDetector not set");
       this.syncContext = checkNotNull(syncContext, "syncContext not set");
       this.serviceConfigParser = checkNotNull(serviceConfigParser, "serviceConfigParser not set");
+      if (channelLogger == null) {
+        this.channelLogger = NOOP_CHANNEL_LOGGER;
+      } else {
+        this.channelLogger = channelLogger;
+      }
       this.executor = executor;
     }
 
@@ -466,6 +483,15 @@ public ServiceConfigParser getServiceConfigParser() {
       return serviceConfigParser;
     }
 
+    /**
+     * Returns the {@link ChannelLogger} for the Channel served by this NameResolver.
+     *
+     * @since 1.26.0
+     */
+    public ChannelLogger getChannelLogger() {
+      return channelLogger;
+    }
+
     /**
      * Returns the Executor on which this resolver should execute long-running or I/O bound work.
      * Null if no Executor was set.
@@ -485,6 +511,7 @@ public String toString() {
           .add("proxyDetector", proxyDetector)
           .add("syncContext", syncContext)
           .add("serviceConfigParser", serviceConfigParser)
+          .add("channelLogger", channelLogger)
           .add("executor", executor)
           .toString();
     }
@@ -500,6 +527,7 @@ public Builder toBuilder() {
       builder.setProxyDetector(proxyDetector);
       builder.setSynchronizationContext(syncContext);
       builder.setServiceConfigParser(serviceConfigParser);
+      builder.setChannelLogger(channelLogger);
       builder.setOffloadExecutor(executor);
       return builder;
     }
@@ -523,6 +551,7 @@ public static final class Builder {
       private ProxyDetector proxyDetector;
       private SynchronizationContext syncContext;
       private ServiceConfigParser serviceConfigParser;
+      private ChannelLogger channelLogger;
       private Executor executor;
 
       Builder() {
@@ -568,6 +597,16 @@ public Builder setServiceConfigParser(ServiceConfigParser parser) {
         return this;
       }
 
+      /**
+       * See {@link Args#getChannelLogger}. This is an optional field.
+       *
+       * @since 1.26.0
+       */
+      public Builder setChannelLogger(ChannelLogger channelLogger) {
+        this.channelLogger = checkNotNull(channelLogger);
+        return this;
+      }
+
       /**
        * See {@link Args#getOffloadExecutor}. This is an optional field.
        *
@@ -585,7 +624,10 @@ public Builder setOffloadExecutor(Executor executor) {
        * @since 1.21.0
        */
       public Args build() {
-        return new Args(defaultPort, proxyDetector, syncContext, serviceConfigParser, executor);
+        return
+            new Args(
+                defaultPort, proxyDetector, syncContext, serviceConfigParser,
+                channelLogger, executor);
       }
     }
   }

api/src/test/java/io/grpc/NameResolverTest.java

@@ -45,6 +45,7 @@ public class NameResolverTest {
   private final SynchronizationContext syncContext =
       new SynchronizationContext(mock(UncaughtExceptionHandler.class));
   private final ServiceConfigParser parser = mock(ServiceConfigParser.class);
+  private final ChannelLogger channelLogger = mock(ChannelLogger.class);
   private final Executor executor = Executors.newSingleThreadExecutor();
   private URI uri;
   private final NameResolver nameResolver = mock(NameResolver.class);
@@ -61,13 +62,15 @@ public void args() {
     assertThat(args.getProxyDetector()).isSameInstanceAs(proxyDetector);
     assertThat(args.getSynchronizationContext()).isSameInstanceAs(syncContext);
     assertThat(args.getServiceConfigParser()).isSameInstanceAs(parser);
+    assertThat(args.getChannelLogger()).isSameInstanceAs(channelLogger);
     assertThat(args.getOffloadExecutor()).isSameInstanceAs(executor);
 
     NameResolver.Args args2 = args.toBuilder().build();
     assertThat(args2.getDefaultPort()).isEqualTo(defaultPort);
     assertThat(args2.getProxyDetector()).isSameInstanceAs(proxyDetector);
     assertThat(args2.getSynchronizationContext()).isSameInstanceAs(syncContext);
     assertThat(args2.getServiceConfigParser()).isSameInstanceAs(parser);
+    assertThat(args2.getChannelLogger()).isSameInstanceAs(channelLogger);
     assertThat(args2.getOffloadExecutor()).isSameInstanceAs(executor);
 
     assertThat(args2).isNotSameInstanceAs(args);
@@ -251,6 +254,7 @@ private NameResolver.Args createArgs() {
         .setProxyDetector(proxyDetector)
         .setSynchronizationContext(syncContext)
         .setServiceConfigParser(parser)
+        .setChannelLogger(channelLogger)
         .setOffloadExecutor(executor)
         .build();
   }

core/src/main/java/io/grpc/internal/ManagedChannelImpl.java

@@ -561,6 +561,12 @@ ClientStream newSubstream(ClientStreamTracer.Factory tracerFactory, Metadata new
       final TimeProvider timeProvider) {
     this.target = checkNotNull(builder.target, "target");
     this.logId = InternalLogId.allocate("Channel", target);
+    this.timeProvider = checkNotNull(timeProvider, "timeProvider");
+    maxTraceEvents = builder.maxTraceEvents;
+    channelTracer = new ChannelTracer(
+        logId, builder.maxTraceEvents, timeProvider.currentTimeNanos(),
+        "Channel for '" + target + "'");
+    channelLogger = new ChannelLoggerImpl(channelTracer, timeProvider);
     this.nameResolverFactory = builder.getNameResolverFactory();
     ProxyDetector proxyDetector =
         builder.proxyDetector != null ? builder.proxyDetector : GrpcUtil.DEFAULT_PROXY_DETECTOR;
@@ -581,6 +587,7 @@ ClientStream newSubstream(ClientStreamTracer.Factory tracerFactory, Metadata new
                     builder.maxRetryAttempts,
                     builder.maxHedgedAttempts,
                     loadBalancerFactory))
+            .setChannelLogger(channelLogger)
             .setOffloadExecutor(
                 // Avoid creating the offloadExecutor until it is first used
                 new Executor() {
@@ -591,12 +598,6 @@ public void execute(Runnable command) {
                 })
             .build();
     this.nameResolver = getNameResolver(target, nameResolverFactory, nameResolverArgs);
-    this.timeProvider = checkNotNull(timeProvider, "timeProvider");
-    maxTraceEvents = builder.maxTraceEvents;
-    channelTracer = new ChannelTracer(
-        logId, builder.maxTraceEvents, timeProvider.currentTimeNanos(),
-        "Channel for '" + target + "'");
-    channelLogger = new ChannelLoggerImpl(channelTracer, timeProvider);
     this.executorPool = checkNotNull(builder.executorPool, "executorPool");
     this.balancerRpcExecutorPool = checkNotNull(balancerRpcExecutorPool, "balancerRpcExecutorPool");
     this.balancerRpcExecutorHolder = new ExecutorHolder(balancerRpcExecutorPool);