suggested changes

Author: AgraVator

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

@@ -201,6 +201,12 @@ public Server build() {
     return delegate().build();
   }
 
+  @Override
+  public T addMetricSink(MetricSink metricSink) {
+    delegate().addMetricSink(metricSink);
+    return thisT();
+  }
+
   @Override
   public String toString() {
     return MoreObjects.toStringHelper(this).add("delegate", delegate()).toString();

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 The gRPC Authors
+ * Copyright 2026 The gRPC Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,8 +27,7 @@
 @Internal
 public final class InternalTcpMetrics {
 
-  private InternalTcpMetrics() {
-  }
+  private InternalTcpMetrics() {}
 
   private static final List<String> OPTIONAL_LABELS = Arrays.asList(
       "network.local.address",
@@ -67,7 +66,8 @@ private InternalTcpMetrics() {
           "{connection}",
           Collections.emptyList(),
           OPTIONAL_LABELS,
-          false);
+          false
+      );
 
   public static final LongCounterMetricInstrument PACKETS_RETRANSMITTED_INSTRUMENT = 
       MetricInstrumentRegistry
@@ -78,7 +78,8 @@ private InternalTcpMetrics() {
           "{packet}",
           Collections.emptyList(),
           OPTIONAL_LABELS,
-          false);
+          false
+      );
 
   public static final LongCounterMetricInstrument RECURRING_RETRANSMITS_INSTRUMENT = 
       MetricInstrumentRegistry
@@ -90,7 +91,8 @@ private InternalTcpMetrics() {
           "{timeout}",
           Collections.emptyList(),
           OPTIONAL_LABELS,
-          false);
+          false
+      );
 
   private static List<Double> getMinRttBuckets() {
     List<Double> buckets = new ArrayList<>(100);

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

@@ -435,6 +435,16 @@ public T setBinaryLog(BinaryLog binaryLog) {
    */
   public abstract Server build();
 
+  /**
+   * Adds a metric sink to the server.
+   *
+   * @param metricSink the metric sink to add.
+   * @return this
+   */
+  public T addMetricSink(MetricSink metricSink) {
+    throw new UnsupportedOperationException();
+  }
+
   /**
    * Returns the correctly typed version of the builder.
    */

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

@@ -92,7 +92,8 @@ final class ClientTransportOptions {
     private Attributes eagAttributes = Attributes.EMPTY;
     @Nullable private String userAgent;
     @Nullable private HttpConnectProxiedSocketAddress connectProxiedSocketAddr;
-    @Nullable private MetricRecorder metricRecorder;
+    private MetricRecorder metricRecorder = new MetricRecorder() {
+    };
 
     public ChannelLogger getChannelLogger() {
       return channelLogger;
@@ -103,13 +104,12 @@ public ClientTransportOptions setChannelLogger(ChannelLogger channelLogger) {
       return this;
     }
 
-    @Nullable
     public MetricRecorder getMetricRecorder() {
       return metricRecorder;
     }
 
-    public ClientTransportOptions setMetricRecorder(@Nullable MetricRecorder metricRecorder) {
-      this.metricRecorder = metricRecorder;
+    public ClientTransportOptions setMetricRecorder(MetricRecorder metricRecorder) {
+      this.metricRecorder = Preconditions.checkNotNull(metricRecorder, "metricRecorder");
       return this;
     }
 

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

@@ -165,6 +165,7 @@ public ServerImplBuilder intercept(ServerInterceptor interceptor) {
   /**
    * Adds a MetricSink to the server.
    */
+  @Override
   public ServerImplBuilder addMetricSink(MetricSink metricSink) {
     metricSinks.add(checkNotNull(metricSink, "metricSink"));
     return this;

core/src/test/java/io/grpc/internal/ServerImplBuilderTest.java

@@ -18,10 +18,13 @@
 
 import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
 
 import io.grpc.InternalConfigurator;
 import io.grpc.InternalConfiguratorRegistry;
 import io.grpc.Metadata;
+import io.grpc.MetricRecorder;
+import io.grpc.MetricSink;
 import io.grpc.ServerBuilder;
 import io.grpc.ServerCall;
 import io.grpc.ServerCallHandler;
@@ -74,7 +77,7 @@ public void setUp() throws Exception {
           @Override
           public InternalServer buildClientTransportServers(
               List<? extends ServerStreamTracer.Factory> streamTracerFactories,
-              io.grpc.MetricRecorder metricRecorder) {
+              MetricRecorder metricRecorder) {
             throw new UnsupportedOperationException();
           }
         });
@@ -129,6 +132,13 @@ public void getTracerFactories_disableBoth() {
     assertThat(factories).containsExactly(DUMMY_USER_TRACER);
   }
 
+  @Test
+  public void addMetricSink_addsToSinks() {
+    MetricSink mockSink = mock(MetricSink.class);
+    builder.addMetricSink(mockSink);
+    assertThat(builder.metricSinks).containsExactly(mockSink);
+  }
+
   @Test
   public void getTracerFactories_callsGet() throws Exception {
     Class<?> runnable = classLoader.loadClass(StaticTestingClassLoaderCallsGet.class.getName());

core/src/test/java/io/grpc/internal/ServerImplTest.java

@@ -65,6 +65,7 @@
 import io.grpc.InternalServerInterceptors;
 import io.grpc.Metadata;
 import io.grpc.MethodDescriptor;
+import io.grpc.MetricRecorder;
 import io.grpc.ServerCall;
 import io.grpc.ServerCall.Listener;
 import io.grpc.ServerCallExecutorSupplier;
@@ -207,7 +208,7 @@ public void startUp() throws IOException {
           @Override
           public InternalServer buildClientTransportServers(
               List<? extends ServerStreamTracer.Factory> streamTracerFactories,
-              io.grpc.MetricRecorder metricRecorder) {
+              MetricRecorder metricRecorder) {
             throw new UnsupportedOperationException();
           }
         });

inprocess/src/main/java/io/grpc/inprocess/InProcessServerBuilder.java

@@ -24,6 +24,7 @@
 import io.grpc.ExperimentalApi;
 import io.grpc.ForwardingServerBuilder;
 import io.grpc.Internal;
+import io.grpc.MetricRecorder;
 import io.grpc.ServerBuilder;
 import io.grpc.ServerStreamTracer;
 import io.grpc.internal.FixedObjectPool;
@@ -121,7 +122,7 @@ final class InProcessClientTransportServersBuilder implements ClientTransportSer
       @Override
       public InternalServer buildClientTransportServers(
           List<? extends ServerStreamTracer.Factory> streamTracerFactories,
-          io.grpc.MetricRecorder metricRecorder) {
+          MetricRecorder metricRecorder) {
         return buildTransportServers(streamTracerFactories);
       }
     }

netty/src/main/java/io/grpc/netty/NettyServerBuilder.java

@@ -32,6 +32,7 @@
 import io.grpc.ExperimentalApi;
 import io.grpc.ForwardingServerBuilder;
 import io.grpc.Internal;
+import io.grpc.MetricSink;
 import io.grpc.ServerBuilder;
 import io.grpc.ServerCredentials;
 import io.grpc.ServerStreamTracer;
@@ -764,6 +765,13 @@ NettyServerBuilder setTransportTracerFactory(TransportTracer.Factory transportTr
     return this;
   }
 
+  @CanIgnoreReturnValue
+  @Override
+  public NettyServerBuilder addMetricSink(MetricSink metricSink) {
+    serverImplBuilder.addMetricSink(metricSink);
+    return this;
+  }
+
   @CanIgnoreReturnValue
   @Override
   public NettyServerBuilder useTransportSecurity(File certChain, File privateKey) {

netty/src/main/java/io/grpc/netty/NettyServerHandler.java

@@ -669,6 +669,12 @@ void setKeepAliveManagerForTest(KeepAliveManager keepAliveManager) {
   /**
    * Handler for the Channel shutting down.
    */
+  @Override
+  public void channelActive(ChannelHandlerContext ctx) throws Exception {
+    tcpMetrics.channelActive(ctx.channel());
+    super.channelActive(ctx);
+  }
+
   @Override
   public void channelInactive(ChannelHandlerContext ctx) throws Exception {
     tcpMetrics.channelInactive(ctx.channel());