Bump version to 1.54.2

ManagedCahnnelImpl did not make sure to use a RetryingNameResolver if
authority was not overriden. This was not a problem for DNS name
resolution as the DNS name resolver factory explicitly returns a
RetryingNameResolver. For polling name resolvers that do not do this in
their factories (like the grpclb name resolver) this meant not having retry
at all.

README.md

@@ -44,8 +44,8 @@ For a guided tour, take a look at the [quick start
 guide](https://grpc.io/docs/languages/java/quickstart) or the more explanatory [gRPC
 basics](https://grpc.io/docs/languages/java/basics).
 
-The [examples](https://github.com/grpc/grpc-java/tree/v1.52.1/examples) and the
-[Android example](https://github.com/grpc/grpc-java/tree/v1.52.1/examples/android)
+The [examples](https://github.com/grpc/grpc-java/tree/v1.54.2/examples) and the
+[Android example](https://github.com/grpc/grpc-java/tree/v1.54.2/examples/android)
 are standalone projects that showcase the usage of gRPC.
 
 Download
@@ -56,18 +56,18 @@ Download [the JARs][]. Or for Maven with non-Android, add to your `pom.xml`:
 <dependency>
   <groupId>io.grpc</groupId>
   <artifactId>grpc-netty-shaded</artifactId>
-  <version>1.52.1</version>
+  <version>1.54.2</version>
   <scope>runtime</scope>
 </dependency>
 <dependency>
   <groupId>io.grpc</groupId>
   <artifactId>grpc-protobuf</artifactId>
-  <version>1.52.1</version>
+  <version>1.54.2</version>
 </dependency>
 <dependency>
   <groupId>io.grpc</groupId>
   <artifactId>grpc-stub</artifactId>
-  <version>1.52.1</version>
+  <version>1.54.2</version>
 </dependency>
 <dependency> <!-- necessary for Java 9+ -->
   <groupId>org.apache.tomcat</groupId>
@@ -79,23 +79,23 @@ Download [the JARs][]. Or for Maven with non-Android, add to your `pom.xml`:
 
 Or for Gradle with non-Android, add to your dependencies:
 ```gradle
-runtimeOnly 'io.grpc:grpc-netty-shaded:1.52.1'
-implementation 'io.grpc:grpc-protobuf:1.52.1'
-implementation 'io.grpc:grpc-stub:1.52.1'
+runtimeOnly 'io.grpc:grpc-netty-shaded:1.54.2'
+implementation 'io.grpc:grpc-protobuf:1.54.2'
+implementation 'io.grpc:grpc-stub:1.54.2'
 compileOnly 'org.apache.tomcat:annotations-api:6.0.53' // necessary for Java 9+
 ```
 
 For Android client, use `grpc-okhttp` instead of `grpc-netty-shaded` and
 `grpc-protobuf-lite` instead of `grpc-protobuf`:
 ```gradle
-implementation 'io.grpc:grpc-okhttp:1.52.1'
-implementation 'io.grpc:grpc-protobuf-lite:1.52.1'
-implementation 'io.grpc:grpc-stub:1.52.1'
+implementation 'io.grpc:grpc-okhttp:1.54.2'
+implementation 'io.grpc:grpc-protobuf-lite:1.54.2'
+implementation 'io.grpc:grpc-stub:1.54.2'
 compileOnly 'org.apache.tomcat:annotations-api:6.0.53' // necessary for Java 9+
 ```
 
 [the JARs]:
-https://search.maven.org/search?q=g:io.grpc%20AND%20v:1.52.1
+https://search.maven.org/search?q=g:io.grpc%20AND%20v:1.54.2
 
 Development snapshots are available in [Sonatypes's snapshot
 repository](https://oss.sonatype.org/content/repositories/snapshots/).
@@ -127,7 +127,7 @@ For protobuf-based codegen integrated with the Maven build system, you can use
       <configuration>
         <protocArtifact>com.google.protobuf:protoc:3.21.7:exe:${os.detected.classifier}</protocArtifact>
         <pluginId>grpc-java</pluginId>
-        <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.52.1:exe:${os.detected.classifier}</pluginArtifact>
+        <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.54.2:exe:${os.detected.classifier}</pluginArtifact>
       </configuration>
       <executions>
         <execution>
@@ -157,7 +157,7 @@ protobuf {
   }
   plugins {
     grpc {
-      artifact = 'io.grpc:protoc-gen-grpc-java:1.52.1'
+      artifact = 'io.grpc:protoc-gen-grpc-java:1.54.2'
     }
   }
   generateProtoTasks {
@@ -190,7 +190,7 @@ protobuf {
   }
   plugins {
     grpc {
-      artifact = 'io.grpc:protoc-gen-grpc-java:1.52.1'
+      artifact = 'io.grpc:protoc-gen-grpc-java:1.54.2'
     }
   }
   generateProtoTasks {

RELEASING.md

@@ -26,18 +26,8 @@ $ VERSION_FILES=(
   examples/android/helloworld/app/build.gradle
   examples/android/routeguide/app/build.gradle
   examples/android/strictmode/app/build.gradle
-  examples/example-alts/build.gradle
-  examples/example-gauth/build.gradle
-  examples/example-gauth/pom.xml
-  examples/example-jwt-auth/build.gradle
-  examples/example-jwt-auth/pom.xml
-  examples/example-hostname/build.gradle
-  examples/example-hostname/pom.xml
-  examples/example-servlet/build.gradle
-  examples/example-tls/build.gradle
-  examples/example-tls/pom.xml
-  examples/example-xds/build.gradle
-  examples/example-orca/build.gradle
+  examples/example-*/build.gradle
+  examples/example-*/pom.xml
   )
 ```
 

build.gradle

@@ -20,7 +20,7 @@ subprojects {
     apply plugin: "net.ltgt.errorprone"
 
     group = "io.grpc"
-    version = "1.54.0-SNAPSHOT" // CURRENT_GRPC_VERSION
+    version = "1.54.2" // CURRENT_GRPC_VERSION
 
     repositories {
         maven { // The google mirror is less flaky than mavenCentral()

buildscripts/grpc-java-artifacts/Dockerfile

@@ -20,6 +20,6 @@ RUN yum install -y \
     yum clean all
 
 # Install Maven
-RUN curl -Ls http://dlcdn.apache.org/maven/maven-3/3.3.9/binaries/apache-maven-3.3.9-bin.tar.gz | \
+RUN curl -Ls https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.3.9/apache-maven-3.3.9-bin.tar.gz | \
     tar xz -C /var/local
 ENV PATH /var/local/apache-maven-3.3.9/bin:$PATH

buildscripts/kokoro/psm-security.cfg

@@ -2,7 +2,7 @@
 
 # Location of the continuous shell script in repository.
 build_file: "grpc-java/buildscripts/kokoro/psm-security.sh"
-timeout_mins: 180
+timeout_mins: 240
 
 action {
   define_artifacts {

buildscripts/kokoro/psm-security.sh

@@ -180,9 +180,6 @@ main() {
     run_test $test || (( ++failed_tests ))
   done
   echo "Failed test suites: ${failed_tests}"
-  if (( failed_tests > 0 )); then
-    exit 1
-  fi
 }
 
 main "$@"

buildscripts/kokoro/xds_k8s_lb.sh

@@ -181,9 +181,6 @@ main() {
     run_test $test || (( ++failed_tests ))
   done
   echo "Failed test suites: ${failed_tests}"
-  if (( failed_tests > 0 )); then
-    exit 1
-  fi
 }
 
 main "$@"

buildscripts/kokoro/xds_url_map.sh

@@ -172,7 +172,7 @@ main() {
   build_docker_images_if_needed
   # Run tests
   cd "${TEST_DRIVER_FULL_DIR}"
-  run_test url_map
+  run_test url_map || echo "Failed url_map test"
 }
 
 main "$@"

buildscripts/observability-test/run.sh

@@ -16,29 +16,14 @@
 set -ex
 cd "$(dirname "$0")"/../..
 
-# TODO(stanleycheung): replace positional parameters with explicit parameters
-#
-#             $1: server | client
-#
-# For server: $2: server_port
-#
-# For client: $2: server_host
-#             $3: server_port
-#             $4: test_case
-#             $5: num_times
-
 if [ "$1" = "server" ] ; then
-  /grpc-java/bin/gcp-observability-interop \
-    server --use_tls=false \
-    --port=$2
+  /grpc-java/bin/gcp-observability-interop server --use_tls=false "${@:2}"
 
 elif [ "$1" = "client" ] ; then
-  /grpc-java/bin/gcp-observability-interop \
-    client --use_tls=false \
-    --server_host=$2 --server_port=$3 \
-    --test_case=$4 --num_times=$5
+  /grpc-java/bin/gcp-observability-interop client --use_tls=false "${@:2}"
 
 else
-  echo "Invalid action: $1"
+  echo "Invalid action: $1. Usage:"
+  echo "  $ .../run.sh [server|client] --server_host=<hostname> --server_port=<port> ..."
   exit 1
 fi

buildscripts/xds-k8s/test-client.Dockerfile

@@ -1,5 +1,5 @@
 # Build runtime image.
-FROM openjdk:11.0.9.1-jdk
+FROM eclipse-temurin:11-jre
 
 ENV APP_DIR=/usr/src/app
 WORKDIR $APP_DIR
@@ -11,5 +11,12 @@ COPY grpc-interop-testing/ $APP_DIR/
 COPY logging*.properties $APP_DIR/
 ENV JAVA_OPTS="-Djava.util.logging.config.file=$APP_DIR/logging-json.properties"
 
+# Intentionally after the app COPY to force the update on each build.
+# Update Ubuntu system packages:
+RUN apt-get update \
+    && apt-get -y upgrade \
+    && apt-get -y autoremove \
+    && rm -rf /var/lib/apt/lists/*
+
 # Client
 ENTRYPOINT ["bin/xds-test-client"]

buildscripts/xds-k8s/test-server.Dockerfile

@@ -1,5 +1,5 @@
 # Build runtime image.
-FROM openjdk:11.0.9.1-jdk
+FROM eclipse-temurin:11-jre
 
 ENV APP_DIR=/usr/src/app
 WORKDIR $APP_DIR
@@ -11,5 +11,12 @@ COPY grpc-interop-testing/ $APP_DIR/
 COPY logging*.properties $APP_DIR/
 ENV JAVA_OPTS="-Djava.util.logging.config.file=$APP_DIR/logging-json.properties"
 
+# Intentionally after the app COPY to force the update on each build.
+# Update Ubuntu system packages:
+RUN apt-get update \
+    && apt-get -y upgrade \
+    && apt-get -y autoremove \
+    && rm -rf /var/lib/apt/lists/*
+
 # Server
 ENTRYPOINT ["bin/xds-test-server"]

census/src/main/java/io/grpc/census/CensusTracingModule.java

@@ -17,6 +17,7 @@
 package io.grpc.census;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static io.grpc.census.internal.ObservabilityCensusConstants.CLIENT_TRACE_SPAN_CONTEXT_KEY;
 
 import com.google.common.annotations.VisibleForTesting;
 import io.grpc.Attributes;
@@ -41,6 +42,9 @@ import io.opencensus.trace.SpanContext;
 import io.opencensus.trace.Status;
 import io.opencensus.trace.Tracer;
 import io.opencensus.trace.propagation.BinaryFormat;
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -92,12 +96,9 @@ final class CensusTracingModule {
   final Metadata.Key<SpanContext> tracingHeader;
   private final TracingClientInterceptor clientInterceptor = new TracingClientInterceptor();
   private final ServerTracerFactory serverTracerFactory = new ServerTracerFactory();
-  private final boolean addMessageEvents;
 
   CensusTracingModule(
-      Tracer censusTracer,
-      final BinaryFormat censusPropagationBinaryFormat,
-      boolean addMessageEvents) {
+      Tracer censusTracer, final BinaryFormat censusPropagationBinaryFormat) {
     this.censusTracer = checkNotNull(censusTracer, "censusTracer");
     checkNotNull(censusPropagationBinaryFormat, "censusPropagationBinaryFormat");
     this.tracingHeader =
@@ -117,7 +118,6 @@ final class CensusTracingModule {
               }
             }
           });
-    this.addMessageEvents = addMessageEvents;
   }
 
   /**
@@ -125,8 +125,8 @@ final class CensusTracingModule {
    */
   @VisibleForTesting
   CallAttemptsTracerFactory newClientCallTracer(
-      @Nullable Span parentSpan, MethodDescriptor<?, ?> method) {
-    return new CallAttemptsTracerFactory(parentSpan, method);
+      @Nullable Span clientSpan, MethodDescriptor<?, ?> method) {
+    return new CallAttemptsTracerFactory(clientSpan, method);
   }
 
   /**
@@ -218,9 +218,6 @@ final class CensusTracingModule {
   private void recordMessageEvent(
       Span span, MessageEvent.Type type,
       int seqNo, long optionalWireSize, long optionalUncompressedSize) {
-    if (!addMessageEvents) {
-      return;
-    }
     MessageEvent.Builder eventBuilder = MessageEvent.builder(type, seqNo);
     if (optionalUncompressedSize != -1) {
       eventBuilder.setUncompressedMessageSize(optionalUncompressedSize);
@@ -231,6 +228,19 @@ final class CensusTracingModule {
     span.addMessageEvent(eventBuilder.build());
   }
 
+  private void recordAnnotation(
+      Span span, MessageEvent.Type type, int seqNo, boolean isCompressed, long size) {
+    String messageType = isCompressed ? "compressed" : "uncompressed";
+    Map<String, AttributeValue> attributes = new HashMap<>();
+    attributes.put("id", AttributeValue.longAttributeValue(seqNo));
+    attributes.put("type", AttributeValue.stringAttributeValue(messageType));
+
+    String messageDirection = type == MessageEvent.Type.SENT ? "↗ " : "↘ ";
+    String inlineDescription =
+        messageDirection + size + " bytes " + type.name().toLowerCase(Locale.US);
+    span.addAnnotation(inlineDescription, attributes);
+  }
+
   @VisibleForTesting
   final class CallAttemptsTracerFactory extends ClientStreamTracer.Factory {
     volatile int callEnded;
@@ -239,17 +249,11 @@ final class CensusTracingModule {
     private final Span span;
     private final String fullMethodName;
 
-    CallAttemptsTracerFactory(@Nullable Span parentSpan, MethodDescriptor<?, ?> method) {
+    CallAttemptsTracerFactory(@Nullable Span clientSpan, MethodDescriptor<?, ?> method) {
       checkNotNull(method, "method");
       this.isSampledToLocalTracing = method.isSampledToLocalTracing();
       this.fullMethodName = method.getFullMethodName();
-      this.span =
-          censusTracer
-              .spanBuilderWithExplicitParent(
-                  generateTraceSpanName(false, fullMethodName),
-                  parentSpan)
-              .setRecordEvents(true)
-              .startSpan();
+      this.span = clientSpan;
     }
 
     @Override
@@ -265,7 +269,7 @@ final class CensusTracingModule {
           "previous-rpc-attempts", AttributeValue.longAttributeValue(info.getPreviousAttempts()));
       attemptSpan.putAttribute(
           "transparent-retry", AttributeValue.booleanAttributeValue(info.isTransparentRetry()));
-      return new ClientTracer(attemptSpan, tracingHeader, isSampledToLocalTracing);
+      return new ClientTracer(attemptSpan, span, tracingHeader, isSampledToLocalTracing);
     }
 
     /**
@@ -291,12 +295,16 @@ final class CensusTracingModule {
 
   private final class ClientTracer extends ClientStreamTracer {
     private final Span span;
+    private final Span parentSpan;
     final Metadata.Key<SpanContext> tracingHeader;
     final boolean isSampledToLocalTracing;
+    volatile int seqNo;
 
     ClientTracer(
-        Span span, Metadata.Key<SpanContext> tracingHeader, boolean isSampledToLocalTracing) {
+        Span span, Span parentSpan, Metadata.Key<SpanContext> tracingHeader,
+        boolean isSampledToLocalTracing) {
       this.span = checkNotNull(span, "span");
+      this.parentSpan = checkNotNull(parentSpan, "parent span");
       this.tracingHeader = tracingHeader;
       this.isSampledToLocalTracing = isSampledToLocalTracing;
     }
@@ -319,8 +327,19 @@ final class CensusTracingModule {
     @Override
     public void inboundMessageRead(
         int seqNo, long optionalWireSize, long optionalUncompressedSize) {
-      recordMessageEvent(
-          span, MessageEvent.Type.RECEIVED, seqNo, optionalWireSize, optionalUncompressedSize);
+      recordAnnotation(
+          span, MessageEvent.Type.RECEIVED, seqNo, true, optionalWireSize);
+    }
+
+    @Override
+    public void inboundMessage(int seqNo) {
+      this.seqNo = seqNo;
+    }
+
+    @Override
+    public void inboundUncompressedSize(long bytes) {
+      recordAnnotation(
+          parentSpan, MessageEvent.Type.RECEIVED, seqNo, false, bytes);
     }
 
     @Override
@@ -334,6 +353,7 @@ final class CensusTracingModule {
     private final Span span;
     volatile boolean isSampledToLocalTracing;
     volatile int streamClosed;
+    private int seqNo;
 
     ServerTracer(String fullMethodName, @Nullable SpanContext remoteSpan) {
       checkNotNull(fullMethodName, "fullMethodName");
@@ -396,8 +416,19 @@ final class CensusTracingModule {
     @Override
     public void inboundMessageRead(
         int seqNo, long optionalWireSize, long optionalUncompressedSize) {
-      recordMessageEvent(
-          span, MessageEvent.Type.RECEIVED, seqNo, optionalWireSize, optionalUncompressedSize);
+      recordAnnotation(
+          span, MessageEvent.Type.RECEIVED, seqNo, true, optionalWireSize);
+    }
+
+    @Override
+    public void inboundMessage(int seqNo) {
+      this.seqNo = seqNo;
+    }
+
+    @Override
+    public void inboundUncompressedSize(long bytes) {
+      recordAnnotation(
+          span, MessageEvent.Type.RECEIVED, seqNo, false, bytes);
     }
   }
 
@@ -425,13 +456,20 @@ final class CensusTracingModule {
       // Safe usage of the unsafe trace API because CONTEXT_SPAN_KEY.get() returns the same value
       // as Tracer.getCurrentSpan() except when no value available when the return value is null
       // for the direct access and BlankSpan when Tracer API is used.
-      final CallAttemptsTracerFactory tracerFactory =
-          newClientCallTracer(
-              io.opencensus.trace.unsafe.ContextUtils.getValue(Context.current()), method);
+      Span parentSpan = io.opencensus.trace.unsafe.ContextUtils.getValue(Context.current());
+      Span clientSpan = censusTracer
+          .spanBuilderWithExplicitParent(
+              generateTraceSpanName(false, method.getFullMethodName()),
+              parentSpan)
+          .setRecordEvents(true)
+          .startSpan();
+
+      final CallAttemptsTracerFactory tracerFactory = newClientCallTracer(clientSpan, method);
       ClientCall<ReqT, RespT> call =
           next.newCall(
               method,
-              callOptions.withStreamTracerFactory(tracerFactory));
+              callOptions.withStreamTracerFactory(tracerFactory)
+                  .withOption(CLIENT_TRACE_SPAN_CONTEXT_KEY, clientSpan.getContext()));
       return new SimpleForwardingClientCall<ReqT, RespT>(call) {
         @Override
         public void start(Listener<RespT> responseListener, Metadata headers) {

census/src/main/java/io/grpc/census/InternalCensusTracingAccessor.java

@@ -36,42 +36,21 @@ public final class InternalCensusTracingAccessor {
    * Returns a {@link ClientInterceptor} with default tracing implementation.
    */
   public static ClientInterceptor getClientInterceptor() {
-    return getClientInterceptor(true);
-  }
-
-  /**
-   * Returns the client interceptor that facilitates Census-based stats reporting.
-   *
-   * @param addMessageEvents add message events to Spans
-   * @return a {@link ClientInterceptor} with default tracing implementation.
-   */
-  public static ClientInterceptor getClientInterceptor(
-      boolean addMessageEvents) {
     CensusTracingModule censusTracing =
         new CensusTracingModule(
             Tracing.getTracer(),
-            Tracing.getPropagationComponent().getBinaryFormat(),
-            addMessageEvents);
+            Tracing.getPropagationComponent().getBinaryFormat());
     return censusTracing.getClientInterceptor();
   }
 
   /**
-   * Returns a {@link ServerStreamTracer.Factory} with default stats implementation.
+   * Returns a {@link ServerStreamTracer.Factory} with default tracing implementation.
    */
   public static ServerStreamTracer.Factory getServerStreamTracerFactory() {
-    return getServerStreamTracerFactory(true);
-  }
-
-  /**
-   * Returns a {@link ServerStreamTracer.Factory} with default stats implementation.
-   */
-  public static ServerStreamTracer.Factory getServerStreamTracerFactory(
-      boolean addMessageEvents) {
     CensusTracingModule censusTracing =
         new CensusTracingModule(
             Tracing.getTracer(),
-            Tracing.getPropagationComponent().getBinaryFormat(),
-            addMessageEvents);
+            Tracing.getPropagationComponent().getBinaryFormat());
     return censusTracing.getServerTracerFactory();
   }
 }

census/src/main/java/io/grpc/census/internal/ObservabilityCensusConstants.java

@@ -26,11 +26,13 @@ import static io.opencensus.contrib.grpc.metrics.RpcMeasureConstants.GRPC_SERVER
 import static io.opencensus.contrib.grpc.metrics.RpcMeasureConstants.GRPC_SERVER_STATUS;
 
 import com.google.common.annotations.VisibleForTesting;
+import io.grpc.CallOptions;
 import io.opencensus.contrib.grpc.metrics.RpcViewConstants;
 import io.opencensus.stats.Aggregation;
 import io.opencensus.stats.Measure;
 import io.opencensus.stats.Measure.MeasureDouble;
 import io.opencensus.stats.View;
+import io.opencensus.trace.SpanContext;
 import java.util.Arrays;
 
 // TODO(dnvindhya): Remove metric and view definitions from this class once it is moved to
@@ -42,6 +44,9 @@ import java.util.Arrays;
 @VisibleForTesting
 public final class ObservabilityCensusConstants {
 
+  public static CallOptions.Key<SpanContext> CLIENT_TRACE_SPAN_CONTEXT_KEY
+      = CallOptions.Key.createWithDefault("Client span context for tracing", SpanContext.INVALID);
+
   static final Aggregation AGGREGATION_WITH_BYTES_HISTOGRAM =
       RpcViewConstants.GRPC_CLIENT_SENT_BYTES_PER_RPC_VIEW.getAggregation();
 

census/src/test/java/io/grpc/census/CensusModulesTest.java

@@ -22,6 +22,7 @@ import static io.grpc.census.CensusStatsModule.CallAttemptsTracerFactory.RETRIES
 import static io.grpc.census.CensusStatsModule.CallAttemptsTracerFactory.RETRY_DELAY_PER_CALL;
 import static io.grpc.census.CensusStatsModule.CallAttemptsTracerFactory.TRANSPARENT_RETRIES_PER_CALL;
 import static io.grpc.census.internal.ObservabilityCensusConstants.API_LATENCY_PER_CALL;
+import static io.grpc.census.internal.ObservabilityCensusConstants.CLIENT_TRACE_SPAN_CONTEXT_KEY;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -100,6 +101,7 @@ import io.opencensus.trace.propagation.SpanContextParseException;
 import java.io.InputStream;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Random;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicReference;
@@ -204,6 +206,8 @@ public class CensusModulesTest {
   private ArgumentCaptor<Status> statusCaptor;
   @Captor
   private ArgumentCaptor<MessageEvent> messageEventCaptor;
+  @Captor
+  private ArgumentCaptor<Map<String, AttributeValue>> annotationAttributesCaptor;
 
   private CensusStatsModule censusStats;
   private CensusTracingModule censusTracing;
@@ -229,7 +233,7 @@ public class CensusModulesTest {
         new CensusStatsModule(
             tagger, tagCtxSerializer, statsRecorder, fakeClock.getStopwatchSupplier(),
             true, true, true, false /* real-time */, true);
-    censusTracing = new CensusTracingModule(tracer, mockTracingPropagationHandler, true);
+    censusTracing = new CensusTracingModule(tracer, mockTracingPropagationHandler);
   }
 
   @After
@@ -314,6 +318,10 @@ public class CensusModulesTest {
         capturedCallOptions.get().getStreamTracerFactories().get(1)
         instanceof CensusStatsModule.CallAttemptsTracerFactory);
 
+    // The interceptor adds client SpanContext to CallOptions
+    assertTrue(capturedCallOptions.get().getOption(CLIENT_TRACE_SPAN_CONTEXT_KEY).isValid());
+    assertTrue(capturedCallOptions.get().getOption(CLIENT_TRACE_SPAN_CONTEXT_KEY) != null);
+
     // Make the call
     Metadata headers = new Metadata();
     call.start(mockClientCallListener, headers);
@@ -735,12 +743,10 @@ public class CensusModulesTest {
   @Test
   public void clientBasicTracingDefaultSpan() {
     CallAttemptsTracerFactory callTracer =
-        censusTracing.newClientCallTracer(null, method);
+        censusTracing.newClientCallTracer(spyClientSpan, method);
     Metadata headers = new Metadata();
     ClientStreamTracer clientStreamTracer = callTracer.newClientStreamTracer(STREAM_INFO, headers);
     clientStreamTracer.streamCreated(Attributes.EMPTY, headers);
-    verify(tracer).spanBuilderWithExplicitParent(
-        eq("Sent.package1.service2.method3"), ArgumentMatchers.<Span>isNull());
     verify(tracer).spanBuilderWithExplicitParent(
         eq("Attempt.package1.service2.method3"), eq(spyClientSpan));
     verify(spyClientSpan, never()).end(any(EndSpanOptions.class));
@@ -761,7 +767,7 @@ public class CensusModulesTest {
         .putAttribute("previous-rpc-attempts", AttributeValue.longAttributeValue(0));
     inOrder.verify(spyAttemptSpan)
         .putAttribute("transparent-retry", AttributeValue.booleanAttributeValue(false));
-    inOrder.verify(spyAttemptSpan, times(3)).addMessageEvent(messageEventCaptor.capture());
+    inOrder.verify(spyAttemptSpan, times(2)).addMessageEvent(messageEventCaptor.capture());
     List<MessageEvent> events = messageEventCaptor.getAllValues();
     assertEquals(
         MessageEvent.builder(MessageEvent.Type.SENT, 0).setCompressedMessageSize(882).build(),
@@ -769,12 +775,14 @@ public class CensusModulesTest {
     assertEquals(
         MessageEvent.builder(MessageEvent.Type.SENT, 1).setUncompressedMessageSize(27).build(),
         events.get(1));
-    assertEquals(
-        MessageEvent.builder(MessageEvent.Type.RECEIVED, 0)
-            .setCompressedMessageSize(255)
-            .setUncompressedMessageSize(90)
-            .build(),
-        events.get(2));
+    ArgumentCaptor<String> stringCaptor = ArgumentCaptor.forClass(String.class);
+    inOrder.verify(spyAttemptSpan, times(1))
+        .addAnnotation(stringCaptor.capture(), annotationAttributesCaptor.capture());
+    assertEquals("↘ 255 bytes received", stringCaptor.getValue());
+    assertThat(annotationAttributesCaptor.getValue().get("id"))
+        .isEqualTo(AttributeValue.longAttributeValue(0));
+    assertThat(annotationAttributesCaptor.getValue().get("type"))
+        .isEqualTo(AttributeValue.stringAttributeValue("compressed"));
     inOrder.verify(spyAttemptSpan).end(
         EndSpanOptions.builder()
             .setStatus(io.opencensus.trace.Status.OK)
@@ -792,7 +800,7 @@ public class CensusModulesTest {
   @Test
   public void clientTracingSampledToLocalSpanStore() {
     CallAttemptsTracerFactory callTracer =
-        censusTracing.newClientCallTracer(null, sampledMethod);
+        censusTracing.newClientCallTracer(spyClientSpan, sampledMethod);
     callTracer.callEnded(Status.OK);
 
     verify(spyClientSpan).end(
@@ -862,10 +870,7 @@ public class CensusModulesTest {
   @Test
   public void clientStreamNeverCreatedStillRecordTracing() {
     CallAttemptsTracerFactory callTracer =
-        censusTracing.newClientCallTracer(fakeClientParentSpan, method);
-    verify(tracer).spanBuilderWithExplicitParent(
-        eq("Sent.package1.service2.method3"), same(fakeClientParentSpan));
-    verify(spyClientSpanBuilder).setRecordEvents(eq(true));
+        censusTracing.newClientCallTracer(spyClientSpan, method);
 
     callTracer.callEnded(Status.DEADLINE_EXCEEDED.withDescription("3 seconds"));
     verify(spyClientSpan).end(
@@ -1041,18 +1046,15 @@ public class CensusModulesTest {
   @Test
   public void traceHeadersPropagateSpanContext() throws Exception {
     CallAttemptsTracerFactory callTracer =
-        censusTracing.newClientCallTracer(fakeClientParentSpan, method);
+        censusTracing.newClientCallTracer(spyClientSpan, method);
     Metadata headers = new Metadata();
     ClientStreamTracer streamTracer = callTracer.newClientStreamTracer(STREAM_INFO, headers);
     streamTracer.streamCreated(Attributes.EMPTY, headers);
 
     verify(mockTracingPropagationHandler).toByteArray(same(fakeAttemptSpanContext));
     verifyNoMoreInteractions(mockTracingPropagationHandler);
-    verify(tracer).spanBuilderWithExplicitParent(
-        eq("Sent.package1.service2.method3"), same(fakeClientParentSpan));
     verify(tracer).spanBuilderWithExplicitParent(
         eq("Attempt.package1.service2.method3"), same(spyClientSpan));
-    verify(spyClientSpanBuilder).setRecordEvents(eq(true));
     verifyNoMoreInteractions(tracer);
     assertTrue(headers.containsKey(censusTracing.tracingHeader));
 
@@ -1310,7 +1312,7 @@ public class CensusModulesTest {
     serverStreamTracer.streamClosed(Status.CANCELLED);
 
     InOrder inOrder = inOrder(spyServerSpan);
-    inOrder.verify(spyServerSpan, times(3)).addMessageEvent(messageEventCaptor.capture());
+    inOrder.verify(spyServerSpan, times(2)).addMessageEvent(messageEventCaptor.capture());
     List<MessageEvent> events = messageEventCaptor.getAllValues();
     assertEquals(
         MessageEvent.builder(MessageEvent.Type.SENT, 0).setCompressedMessageSize(882).build(),
@@ -1318,12 +1320,16 @@ public class CensusModulesTest {
     assertEquals(
         MessageEvent.builder(MessageEvent.Type.SENT, 1).setUncompressedMessageSize(27).build(),
         events.get(1));
-    assertEquals(
-        MessageEvent.builder(MessageEvent.Type.RECEIVED, 0)
-            .setCompressedMessageSize(255)
-            .setUncompressedMessageSize(90)
-            .build(),
-        events.get(2));
+
+    ArgumentCaptor<String> stringCaptor = ArgumentCaptor.forClass(String.class);
+    inOrder.verify(spyServerSpan, times(1))
+        .addAnnotation(stringCaptor.capture(), annotationAttributesCaptor.capture());
+    assertEquals("↘ 255 bytes received", stringCaptor.getValue());
+    assertThat(annotationAttributesCaptor.getValue().get("id"))
+        .isEqualTo(AttributeValue.longAttributeValue(0));
+    assertThat(annotationAttributesCaptor.getValue().get("type"))
+        .isEqualTo(AttributeValue.stringAttributeValue("compressed"));
+
     inOrder.verify(spyServerSpan).end(
         EndSpanOptions.builder()
             .setStatus(io.opencensus.trace.Status.CANCELLED)

census/src/test/java/io/grpc/census/CensusTracingAnnotationEventTest.java

@@ -16,6 +16,8 @@
 
 package io.grpc.census;
 
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
@@ -35,6 +37,7 @@ import io.grpc.census.CensusTracingModule.CallAttemptsTracerFactory;
 import io.grpc.internal.testing.StatsTestUtils.FakeStatsRecorder;
 import io.grpc.internal.testing.StatsTestUtils.MockableSpan;
 import io.grpc.testing.GrpcServerRule;
+import io.opencensus.trace.AttributeValue;
 import io.opencensus.trace.MessageEvent;
 import io.opencensus.trace.Span;
 import io.opencensus.trace.SpanBuilder;
@@ -42,6 +45,8 @@ import io.opencensus.trace.SpanContext;
 import io.opencensus.trace.Tracer;
 import io.opencensus.trace.propagation.BinaryFormat;
 import java.io.InputStream;
+import java.util.List;
+import java.util.Map;
 import java.util.Random;
 import org.junit.After;
 import org.junit.Before;
@@ -61,7 +66,7 @@ import org.mockito.junit.MockitoRule;
  * Test for {@link CensusTracingModule}.
  */
 @RunWith(JUnit4.class)
-public class CensusTracingNoMessageEventTest {
+public class CensusTracingAnnotationEventTest {
   private static final ClientStreamTracer.StreamInfo STREAM_INFO =
       ClientStreamTracer.StreamInfo.newBuilder().build();
 
@@ -125,6 +130,9 @@ public class CensusTracingNoMessageEventTest {
 
   @Captor
   private ArgumentCaptor<MessageEvent> messageEventCaptor;
+  @Captor
+  private ArgumentCaptor<Map<String, AttributeValue>> annotationAttributesCaptor;
+  private ArgumentCaptor<String> stringCaptor;
 
   private CensusTracingModule censusTracing;
 
@@ -145,8 +153,9 @@ public class CensusTracingNoMessageEventTest {
         .thenReturn(binarySpanContext);
     when(mockTracingPropagationHandler.fromByteArray(any(byte[].class)))
         .thenReturn(fakeAttemptSpanContext);
+    stringCaptor = ArgumentCaptor.forClass(String.class);
 
-    censusTracing = new CensusTracingModule(tracer, mockTracingPropagationHandler, false);
+    censusTracing = new CensusTracingModule(tracer, mockTracingPropagationHandler);
   }
 
   @After
@@ -155,9 +164,9 @@ public class CensusTracingNoMessageEventTest {
   }
 
   @Test
-  public void clientBasicTracingNoMessageEvents() {
+  public void clientBasicTracingUncompressedSizeAnnotation() {
     CallAttemptsTracerFactory callTracer =
-        censusTracing.newClientCallTracer(null, method);
+        censusTracing.newClientCallTracer(spyClientSpan, method);
     Metadata headers = new Metadata();
     ClientStreamTracer clientStreamTracer = callTracer.newClientStreamTracer(STREAM_INFO, headers);
     clientStreamTracer.streamCreated(Attributes.EMPTY, headers);
@@ -168,16 +177,63 @@ public class CensusTracingNoMessageEventTest {
     clientStreamTracer.outboundMessage(1);
     clientStreamTracer.outboundMessageSent(1, -1, 27);
     clientStreamTracer.inboundMessageRead(0, 255, 90);
+    clientStreamTracer.inboundUncompressedSize(90);
+    clientStreamTracer.inboundMessage(1);
+    clientStreamTracer.inboundMessageRead(1, 128, 60);
+    clientStreamTracer.inboundUncompressedSize(60);
 
     clientStreamTracer.streamClosed(Status.OK);
     callTracer.callEnded(Status.OK);
 
     InOrder inOrder = inOrder(spyClientSpan, spyAttemptSpan);
-    inOrder.verify(spyAttemptSpan, times(0)).addMessageEvent(messageEventCaptor.capture());
+    inOrder.verify(spyAttemptSpan, times(2)).addMessageEvent(messageEventCaptor.capture());
+    List<MessageEvent> events = messageEventCaptor.getAllValues();
+    assertEquals(
+        MessageEvent.builder(MessageEvent.Type.SENT, 0).setCompressedMessageSize(882).build(),
+        events.get(0));
+    assertEquals(
+        MessageEvent.builder(MessageEvent.Type.SENT, 1).setUncompressedMessageSize(27).build(),
+        events.get(1));
+
+    inOrder
+        .verify(spyAttemptSpan, times(1))
+        .addAnnotation(stringCaptor.capture(), annotationAttributesCaptor.capture());
+    assertEquals("↘ 255 bytes received", stringCaptor.getValue());
+    assertThat(annotationAttributesCaptor.getValue().get("id"))
+        .isEqualTo(AttributeValue.longAttributeValue(0));
+    assertThat(annotationAttributesCaptor.getValue().get("type"))
+        .isEqualTo(AttributeValue.stringAttributeValue("compressed"));
+
+    inOrder
+        .verify(spyClientSpan, times(1))
+        .addAnnotation(stringCaptor.capture(), annotationAttributesCaptor.capture());
+    assertEquals("↘ 90 bytes received", stringCaptor.getValue());
+    assertThat(annotationAttributesCaptor.getValue().get("id"))
+        .isEqualTo(AttributeValue.longAttributeValue(0));
+    assertThat(annotationAttributesCaptor.getValue().get("type"))
+        .isEqualTo(AttributeValue.stringAttributeValue("uncompressed"));
+
+    inOrder
+        .verify(spyAttemptSpan, times(1))
+        .addAnnotation(stringCaptor.capture(), annotationAttributesCaptor.capture());
+    assertEquals("↘ 128 bytes received", stringCaptor.getValue());
+    assertThat(annotationAttributesCaptor.getValue().get("id"))
+        .isEqualTo(AttributeValue.longAttributeValue(1));
+    assertThat(annotationAttributesCaptor.getValue().get("type"))
+        .isEqualTo(AttributeValue.stringAttributeValue("compressed"));
+
+    inOrder
+        .verify(spyClientSpan, times(1))
+        .addAnnotation(stringCaptor.capture(), annotationAttributesCaptor.capture());
+    assertEquals("↘ 60 bytes received", stringCaptor.getValue());
+    assertThat(annotationAttributesCaptor.getValue().get("id"))
+        .isEqualTo(AttributeValue.longAttributeValue(1));
+    assertThat(annotationAttributesCaptor.getValue().get("type"))
+        .isEqualTo(AttributeValue.stringAttributeValue("uncompressed"));
   }
 
   @Test
-  public void serverBasicTracingNoMessageEvents() {
+  public void serverBasicTracingUncompressedSizeAnnotation() {
     ServerStreamTracer.Factory tracerFactory = censusTracing.getServerTracerFactory();
     ServerStreamTracer serverStreamTracer =
         tracerFactory.newServerStreamTracer(method.getFullMethodName(), new Metadata());
@@ -191,10 +247,37 @@ public class CensusTracingNoMessageEventTest {
     serverStreamTracer.outboundMessage(1);
     serverStreamTracer.outboundMessageSent(1, -1, 27);
     serverStreamTracer.inboundMessageRead(0, 255, 90);
+    serverStreamTracer.inboundUncompressedSize(90);
 
     serverStreamTracer.streamClosed(Status.CANCELLED);
 
     InOrder inOrder = inOrder(spyServerSpan);
-    inOrder.verify(spyServerSpan, times(0)).addMessageEvent(messageEventCaptor.capture());
+    inOrder.verify(spyServerSpan, times(2)).addMessageEvent(messageEventCaptor.capture());
+    List<MessageEvent> events = messageEventCaptor.getAllValues();
+    assertEquals(
+        MessageEvent.builder(MessageEvent.Type.SENT, 0).setCompressedMessageSize(882).build(),
+        events.get(0));
+    assertEquals(
+        MessageEvent.builder(MessageEvent.Type.SENT, 1).setUncompressedMessageSize(27).build(),
+        events.get(1));
+
+    inOrder
+        .verify(spyServerSpan, times(2))
+        .addAnnotation(stringCaptor.capture(), annotationAttributesCaptor.capture());
+    List<String> annotationDescriptions = stringCaptor.getAllValues();
+    List<Map<String, AttributeValue>> annotationAttributes =
+        annotationAttributesCaptor.getAllValues();
+
+    assertEquals("↘ 255 bytes received", annotationDescriptions.get(0));
+    assertThat(annotationAttributes.get(0).get("id"))
+        .isEqualTo(AttributeValue.longAttributeValue(0));
+    assertThat(annotationAttributes.get(0).get("type"))
+        .isEqualTo(AttributeValue.stringAttributeValue("compressed"));
+
+    assertEquals("↘ 90 bytes received", annotationDescriptions.get(1));
+    assertThat(annotationAttributes.get(1).get("id"))
+        .isEqualTo(AttributeValue.longAttributeValue(0));
+    assertThat(annotationAttributes.get(1).get("type"))
+        .isEqualTo(AttributeValue.stringAttributeValue("uncompressed"));
   }
 }

compiler/src/test/golden/TestDeprecatedService.java.txt

@@ -8,7 +8,7 @@ import static io.grpc.MethodDescriptor.generateFullMethodName;
  * </pre>
  */
 @javax.annotation.Generated(
-    value = "by gRPC proto compiler (version 1.54.0-SNAPSHOT)",
+    value = "by gRPC proto compiler (version 1.54.2)",
     comments = "Source: grpc/testing/compiler/test.proto")
 @io.grpc.stub.annotations.GrpcGenerated
 @java.lang.Deprecated

compiler/src/test/golden/TestService.java.txt

@@ -8,7 +8,7 @@ import static io.grpc.MethodDescriptor.generateFullMethodName;
  * </pre>
  */
 @javax.annotation.Generated(
-    value = "by gRPC proto compiler (version 1.54.0-SNAPSHOT)",
+    value = "by gRPC proto compiler (version 1.54.2)",
     comments = "Source: grpc/testing/compiler/test.proto")
 @io.grpc.stub.annotations.GrpcGenerated
 public final class TestServiceGrpc {

compiler/src/testLite/golden/TestDeprecatedService.java.txt

@@ -8,7 +8,7 @@ import static io.grpc.MethodDescriptor.generateFullMethodName;
  * </pre>
  */
 @javax.annotation.Generated(
-    value = "by gRPC proto compiler (version 1.54.0-SNAPSHOT)",
+    value = "by gRPC proto compiler (version 1.54.2)",
     comments = "Source: grpc/testing/compiler/test.proto")
 @io.grpc.stub.annotations.GrpcGenerated
 @java.lang.Deprecated

compiler/src/testLite/golden/TestService.java.txt

@@ -8,7 +8,7 @@ import static io.grpc.MethodDescriptor.generateFullMethodName;
  * </pre>
  */
 @javax.annotation.Generated(
-    value = "by gRPC proto compiler (version 1.54.0-SNAPSHOT)",
+    value = "by gRPC proto compiler (version 1.54.2)",
     comments = "Source: grpc/testing/compiler/test.proto")
 @io.grpc.stub.annotations.GrpcGenerated
 public final class TestServiceGrpc {

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

@@ -217,7 +217,7 @@ public final class GrpcUtil {
 
   public static final Splitter ACCEPT_ENCODING_SPLITTER = Splitter.on(',').trimResults();
 
-  private static final String IMPLEMENTATION_VERSION = "1.54.0-SNAPSHOT"; // CURRENT_GRPC_VERSION
+  private static final String IMPLEMENTATION_VERSION = "1.54.2"; // CURRENT_GRPC_VERSION
 
   /**
    * The default timeout in nanos for a keepalive ping request.

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

@@ -748,9 +748,6 @@ final class ManagedChannelImpl extends ManagedChannel implements
       String target, @Nullable final String overrideAuthority,
       NameResolver.Factory nameResolverFactory, NameResolver.Args nameResolverArgs) {
     NameResolver resolver = getNameResolver(target, nameResolverFactory, nameResolverArgs);
-    if (overrideAuthority == null) {
-      return resolver;
-    }
 
     // If the nameResolver is not already a RetryingNameResolver, then wrap it with it.
     // This helps guarantee that name resolution retry remains supported even as it has been
@@ -768,6 +765,10 @@ final class ManagedChannelImpl extends ManagedChannel implements
           nameResolverArgs.getSynchronizationContext());
     }
 
+    if (overrideAuthority == null) {
+      return usedNameResolver;
+    }
+
     return new ForwardingNameResolver(usedNameResolver) {
       @Override
       public String getServiceAuthority() {

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

@@ -282,14 +282,12 @@ abstract class RetriableStream<ReqT> implements ClientStream {
 
       synchronized (lock) {
         savedState = state;
-        if (streamStarted) {
-          if (savedState.winningSubstream != null && savedState.winningSubstream != substream) {
-            // committed but not me, to be cancelled
-            break;
-          }
-          if (savedState.cancelled) {
-            break;
-          }
+        if (savedState.winningSubstream != null && savedState.winningSubstream != substream) {
+          // committed but not me, to be cancelled
+          break;
+        }
+        if (savedState.cancelled) {
+          break;
         }
         if (index == savedState.buffer.size()) { // I'm drained
           state = savedState.substreamDrained(substream);
@@ -326,15 +324,13 @@ abstract class RetriableStream<ReqT> implements ClientStream {
         if (bufferEntry instanceof RetriableStream.StartEntry) {
           streamStarted = true;
         }
-        if (streamStarted) {
-          savedState = state;
-          if (savedState.winningSubstream != null && savedState.winningSubstream != substream) {
-            // committed but not me, to be cancelled
-            break;
-          }
-          if (savedState.cancelled) {
-            break;
-          }
+        savedState = state;
+        if (savedState.winningSubstream != null && savedState.winningSubstream != substream) {
+          // committed but not me, to be cancelled
+          break;
+        }
+        if (savedState.cancelled) {
+          break;
         }
       }
     }
@@ -344,6 +340,10 @@ abstract class RetriableStream<ReqT> implements ClientStream {
       return;
     }
 
+    if (!streamStarted) {
+      // Start stream so inFlightSubStreams is decremented in Sublistener.closed()
+      substream.stream.start(new Sublistener(substream));
+    }
     substream.stream.cancel(
         state.winningSubstream == substream ? cancellationStatus : CANCELLED_BECAUSE_COMMITTED);
   }
@@ -484,6 +484,8 @@ abstract class RetriableStream<ReqT> implements ClientStream {
               }
 
               if (cancelled) {
+                // Start stream so inFlightSubStreams is decremented in Sublistener.closed()
+                newSubstream.stream.start(new Sublistener(newSubstream));
                 newSubstream.stream.cancel(Status.CANCELLED.withDescription("Unneeded hedging"));
                 return;
               }
@@ -507,6 +509,9 @@ abstract class RetriableStream<ReqT> implements ClientStream {
     Runnable runnable = commit(noopSubstream);
 
     if (runnable != null) {
+      synchronized (lock) {
+        state = state.substreamDrained(noopSubstream);
+      }
       runnable.run();
       safeCloseMasterListener(reason, RpcProgress.PROCESSED, new Metadata());
       return;
@@ -927,29 +932,15 @@ abstract class RetriableStream<ReqT> implements ClientStream {
             return;
           }
           if (isHedging) {
-            boolean commit = false;
             synchronized (lock) {
               // Although this operation is not done atomically with
               // noMoreTransparentRetry.compareAndSet(false, true), it does not change the size() of
               // activeHedges, so neither does it affect the commitment decision of other threads,
               // nor do the commitment decision making threads affect itself.
               state = state.replaceActiveHedge(substream, newSubstream);
-
-              // optimization for early commit
-              if (!hasPotentialHedging(state)
-                  && state.activeHedges.size() == 1) {
-                commit = true;
-              }
-            }
-            if (commit) {
-              commitAndRun(newSubstream);
-            }
-          } else {
-            if (retryPolicy == null || retryPolicy.maxAttempts == 1) {
-              // optimization for early commit
-              commitAndRun(newSubstream);
             }
           }
+
           callExecutor.execute(new Runnable() {
             @Override
             public void run() {

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

@@ -139,8 +139,9 @@ public class ManagedChannelImplGetNameResolverTest {
 
   private void testValidTarget(String target, String expectedUriString, URI expectedUri) {
     NameResolver.Factory nameResolverFactory = new FakeNameResolverFactory(expectedUri.getScheme());
-    FakeNameResolver nameResolver = (FakeNameResolver) ManagedChannelImpl.getNameResolver(
-        target, null, nameResolverFactory, NAMERESOLVER_ARGS);
+    FakeNameResolver nameResolver
+        = (FakeNameResolver) ((RetryingNameResolver) ManagedChannelImpl.getNameResolver(
+            target, null, nameResolverFactory, NAMERESOLVER_ARGS)).getRetriedNameResolver();
     assertNotNull(nameResolver);
     assertEquals(expectedUri, nameResolver.uri);
     assertEquals(expectedUriString, nameResolver.uri.toString());

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

@@ -279,6 +279,11 @@ public class ManagedChannelImplTest {
       ArgumentCaptor.forClass(ClientStreamListener.class);
 
   private void createChannel(ClientInterceptor... interceptors) {
+    createChannel(false, interceptors);
+  }
+
+  private void createChannel(boolean nameResolutionExpectedToFail,
+      ClientInterceptor... interceptors) {
     checkState(channel == null);
 
     channel = new ManagedChannelImpl(
@@ -287,7 +292,7 @@ public class ManagedChannelImplTest {
         timer.getTimeProvider());
 
     if (requestConnection) {
-      int numExpectedTasks = 0;
+      int numExpectedTasks = nameResolutionExpectedToFail ? 1 : 0;
 
       // Force-exit the initial idle-mode
       channel.syncContext.execute(new Runnable() {
@@ -2955,7 +2960,7 @@ public class ManagedChannelImplTest {
     FakeNameResolverFactory nameResolverFactory =
         new FakeNameResolverFactory.Builder(expectedUri).setError(error).build();
     channelBuilder.nameResolverFactory(nameResolverFactory);
-    createChannel();
+    createChannel(true);
 
     assertThat(getStats(channel).channelTrace.events).contains(new ChannelTrace.Event.Builder()
         .setDescription("Failed to resolve name: " + error)
@@ -3458,10 +3463,11 @@ public class ManagedChannelImplTest {
     ArgumentCaptor<Helper> helperCaptor = ArgumentCaptor.forClass(Helper.class);
     verify(mockLoadBalancerProvider).newLoadBalancer(helperCaptor.capture());
     helper = helperCaptor.getValue();
-    verify(mockLoadBalancer).acceptResolvedAddresses(
-        ResolvedAddresses.newBuilder()
-            .setAddresses(nameResolverFactory.servers)
-            .build());
+    verify(mockLoadBalancer).acceptResolvedAddresses(resolvedAddressCaptor.capture());
+    ResolvedAddresses resolvedAddresses = resolvedAddressCaptor.getValue();
+    assertThat(resolvedAddresses.getAddresses()).isEqualTo(nameResolverFactory.servers);
+    assertThat(resolvedAddresses.getAttributes()
+        .get(RetryingNameResolver.RESOLUTION_RESULT_LISTENER_KEY)).isNotNull();
 
     // simulating request connection and then transport ready after resolved address
     Subchannel subchannel =
@@ -3564,10 +3570,11 @@ public class ManagedChannelImplTest {
     ArgumentCaptor<Helper> helperCaptor = ArgumentCaptor.forClass(Helper.class);
     verify(mockLoadBalancerProvider).newLoadBalancer(helperCaptor.capture());
     helper = helperCaptor.getValue();
-    verify(mockLoadBalancer).acceptResolvedAddresses(
-        ResolvedAddresses.newBuilder()
-            .setAddresses(nameResolverFactory.servers)
-            .build());
+    verify(mockLoadBalancer).acceptResolvedAddresses(resolvedAddressCaptor.capture());
+    ResolvedAddresses resolvedAddresses = resolvedAddressCaptor.getValue();
+    assertThat(resolvedAddresses.getAddresses()).isEqualTo(nameResolverFactory.servers);
+    assertThat(resolvedAddresses.getAttributes()
+        .get(RetryingNameResolver.RESOLUTION_RESULT_LISTENER_KEY)).isNotNull();
 
     // simulating request connection and then transport ready after resolved address
     Subchannel subchannel =

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

@@ -188,7 +188,7 @@ public class RetriableStreamTest {
     }
   }
 
-  private final RetriableStream<String> retriableStream =
+  private RetriableStream<String> retriableStream =
       newThrottledRetriableStream(null /* throttle */);
   private final RetriableStream<String> hedgingStream =
       newThrottledHedgingStream(null /* throttle */);
@@ -196,10 +196,13 @@ public class RetriableStreamTest {
   private ClientStreamTracer bufferSizeTracer;
 
   private RetriableStream<String> newThrottledRetriableStream(Throttle throttle) {
+    return newThrottledRetriableStream(throttle, MoreExecutors.directExecutor());
+  }
+
+  private RetriableStream<String> newThrottledRetriableStream(Throttle throttle, Executor drainer) {
     return new RecordedRetriableStream(
         method, new Metadata(), channelBufferUsed, PER_RPC_BUFFER_LIMIT, CHANNEL_BUFFER_LIMIT,
-        MoreExecutors.directExecutor(), fakeClock.getScheduledExecutorService(), RETRY_POLICY,
-        null, throttle);
+        drainer, fakeClock.getScheduledExecutorService(), RETRY_POLICY, null, throttle);
   }
 
   private RetriableStream<String> newThrottledHedgingStream(Throttle throttle) {
@@ -598,6 +601,44 @@ public class RetriableStreamTest {
     inOrder.verify(retriableStreamRecorder, never()).postCommit();
   }
 
+  @Test
+  public void transparentRetry_cancel_race() {
+    FakeClock drainer = new FakeClock();
+    retriableStream = newThrottledRetriableStream(null, drainer.getScheduledExecutorService());
+    ClientStream mockStream1 = mock(ClientStream.class);
+    doReturn(mockStream1).when(retriableStreamRecorder).newSubstream(0);
+    InOrder inOrder = inOrder(retriableStreamRecorder);
+
+    retriableStream.start(masterListener);
+
+    ArgumentCaptor<ClientStreamListener> sublistenerCaptor1 =
+        ArgumentCaptor.forClass(ClientStreamListener.class);
+    verify(mockStream1).start(sublistenerCaptor1.capture());
+
+    // retry, but don't drain
+    ClientStream mockStream2 = mock(ClientStream.class);
+    doReturn(mockStream2).when(retriableStreamRecorder).newSubstream(0);
+    sublistenerCaptor1.getValue().closed(
+        Status.fromCode(NON_RETRIABLE_STATUS_CODE), MISCARRIED, new Metadata());
+    assertEquals(1, drainer.numPendingTasks());
+
+    // cancel
+    retriableStream.cancel(Status.CANCELLED);
+    // drain transparent retry
+    drainer.runDueTasks();
+    inOrder.verify(retriableStreamRecorder).postCommit();
+
+    ArgumentCaptor<ClientStreamListener> sublistenerCaptor2 =
+        ArgumentCaptor.forClass(ClientStreamListener.class);
+    verify(mockStream2).start(sublistenerCaptor2.capture());
+    ArgumentCaptor<Status> statusCaptor = ArgumentCaptor.forClass(Status.class);
+    verify(mockStream2).cancel(statusCaptor.capture());
+    assertEquals(Status.CANCELLED.getCode(), statusCaptor.getValue().getCode());
+    assertEquals(CANCELLED_BECAUSE_COMMITTED, statusCaptor.getValue().getDescription());
+    sublistenerCaptor2.getValue().closed(statusCaptor.getValue(), PROCESSED, new Metadata());
+    verify(masterListener).closed(same(Status.CANCELLED), same(PROCESSED), any(Metadata.class));
+  }
+
   @Test
   public void unretriableClosed_cancel() {
     ClientStream mockStream1 = mock(ClientStream.class);
@@ -1930,7 +1971,7 @@ public class RetriableStreamTest {
   }
 
   @Test
-  public void noRetry_transparentRetry_earlyCommit() {
+  public void noRetry_transparentRetry_noEarlyCommit() {
     ClientStream mockStream1 = mock(ClientStream.class);
     ClientStream mockStream2 = mock(ClientStream.class);
     InOrder inOrder = inOrder(retriableStreamRecorder, mockStream1, mockStream2);
@@ -1958,7 +1999,7 @@ public class RetriableStreamTest {
     inOrder.verify(retriableStreamRecorder).newSubstream(0);
     ArgumentCaptor<ClientStreamListener> sublistenerCaptor2 =
         ArgumentCaptor.forClass(ClientStreamListener.class);
-    inOrder.verify(retriableStreamRecorder).postCommit();
+    verify(retriableStreamRecorder, never()).postCommit();
     inOrder.verify(mockStream2).start(sublistenerCaptor2.capture());
     inOrder.verify(mockStream2).isReady();
     inOrder.verifyNoMoreInteractions();

cronet/README.md

@@ -26,7 +26,7 @@ In your app module's `build.gradle` file, include a dependency on both `grpc-cro
 Google Play Services Client Library for Cronet
 
 ```
-implementation 'io.grpc:grpc-cronet:1.52.1'
+implementation 'io.grpc:grpc-cronet:1.54.1'
 implementation 'com.google.android.gms:play-services-cronet:16.0.0'
 ```
 

documentation/android-channel-builder.md

@@ -36,8 +36,8 @@ In your `build.gradle` file, include a dependency on both `grpc-android` and
 `grpc-okhttp`:
 
 ```
-implementation 'io.grpc:grpc-android:1.52.1'
-implementation 'io.grpc:grpc-okhttp:1.52.1'
+implementation 'io.grpc:grpc-android:1.54.1'
+implementation 'io.grpc:grpc-okhttp:1.54.1'
 ```
 
 You also need permission to access the device's network state in your

examples/android/clientcache/app/build.gradle

@@ -34,7 +34,7 @@ android {
 protobuf {
     protoc { artifact = 'com.google.protobuf:protoc:3.21.7' }
     plugins {
-        grpc { artifact = 'io.grpc:protoc-gen-grpc-java:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+        grpc { artifact = 'io.grpc:protoc-gen-grpc-java:1.54.2' // CURRENT_GRPC_VERSION
         }
     }
     generateProtoTasks {
@@ -54,12 +54,12 @@ dependencies {
     implementation 'com.android.support:appcompat-v7:27.0.2'
 
     // You need to build grpc-java to obtain these libraries below.
-    implementation 'io.grpc:grpc-okhttp:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
-    implementation 'io.grpc:grpc-protobuf-lite:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
-    implementation 'io.grpc:grpc-stub:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-okhttp:1.54.2' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-protobuf-lite:1.54.2' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-stub:1.54.2' // CURRENT_GRPC_VERSION
     implementation 'org.apache.tomcat:annotations-api:6.0.53'
 
     testImplementation 'junit:junit:4.13.2'
     testImplementation 'com.google.truth:truth:1.0.1'
-    testImplementation 'io.grpc:grpc-testing:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+    testImplementation 'io.grpc:grpc-testing:1.54.2' // CURRENT_GRPC_VERSION
 }

examples/android/helloworld/app/build.gradle

@@ -32,7 +32,7 @@ android {
 protobuf {
     protoc { artifact = 'com.google.protobuf:protoc:3.21.7' }
     plugins {
-        grpc { artifact = 'io.grpc:protoc-gen-grpc-java:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+        grpc { artifact = 'io.grpc:protoc-gen-grpc-java:1.54.2' // CURRENT_GRPC_VERSION
         }
     }
     generateProtoTasks {
@@ -52,8 +52,8 @@ dependencies {
     implementation 'com.android.support:appcompat-v7:27.0.2'
 
     // You need to build grpc-java to obtain these libraries below.
-    implementation 'io.grpc:grpc-okhttp:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
-    implementation 'io.grpc:grpc-protobuf-lite:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
-    implementation 'io.grpc:grpc-stub:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-okhttp:1.54.2' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-protobuf-lite:1.54.2' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-stub:1.54.2' // CURRENT_GRPC_VERSION
     implementation 'org.apache.tomcat:annotations-api:6.0.53'
 }

examples/android/routeguide/app/build.gradle

@@ -32,7 +32,7 @@ android {
 protobuf {
     protoc { artifact = 'com.google.protobuf:protoc:3.21.7' }
     plugins {
-        grpc { artifact = 'io.grpc:protoc-gen-grpc-java:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+        grpc { artifact = 'io.grpc:protoc-gen-grpc-java:1.54.2' // CURRENT_GRPC_VERSION
         }
     }
     generateProtoTasks {
@@ -52,8 +52,8 @@ dependencies {
     implementation 'com.android.support:appcompat-v7:27.0.2'
 
     // You need to build grpc-java to obtain these libraries below.
-    implementation 'io.grpc:grpc-okhttp:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
-    implementation 'io.grpc:grpc-protobuf-lite:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
-    implementation 'io.grpc:grpc-stub:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-okhttp:1.54.2' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-protobuf-lite:1.54.2' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-stub:1.54.2' // CURRENT_GRPC_VERSION
     implementation 'org.apache.tomcat:annotations-api:6.0.53'
 }

examples/android/strictmode/app/build.gradle

@@ -33,7 +33,7 @@ android {
 protobuf {
     protoc { artifact = 'com.google.protobuf:protoc:3.21.7' }
     plugins {
-        grpc { artifact = 'io.grpc:protoc-gen-grpc-java:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+        grpc { artifact = 'io.grpc:protoc-gen-grpc-java:1.54.2' // CURRENT_GRPC_VERSION
         }
     }
     generateProtoTasks {
@@ -53,8 +53,8 @@ dependencies {
     implementation 'com.android.support:appcompat-v7:28.0.0'
 
     // You need to build grpc-java to obtain these libraries below.
-    implementation 'io.grpc:grpc-okhttp:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
-    implementation 'io.grpc:grpc-protobuf-lite:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
-    implementation 'io.grpc:grpc-stub:1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-okhttp:1.54.2' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-protobuf-lite:1.54.2' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-stub:1.54.2' // CURRENT_GRPC_VERSION
     implementation 'org.apache.tomcat:annotations-api:6.0.53'
 }

examples/build.gradle

@@ -21,7 +21,7 @@ targetCompatibility = 1.8
 
 // Feel free to delete the comment at the next line. It is just for safely
 // updating the version in our release process.
-def grpcVersion = '1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def grpcVersion = '1.54.2' // CURRENT_GRPC_VERSION
 def protobufVersion = '3.21.7'
 def protocVersion = protobufVersion
 

examples/example-alts/build.gradle

@@ -23,7 +23,7 @@ targetCompatibility = 1.8
 
 // Feel free to delete the comment at the next line. It is just for safely
 // updating the version in our release process.
-def grpcVersion = '1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def grpcVersion = '1.54.2' // CURRENT_GRPC_VERSION
 def protocVersion = '3.21.7'
 
 dependencies {

examples/example-gauth/build.gradle

@@ -23,7 +23,7 @@ targetCompatibility = 1.8
 
 // Feel free to delete the comment at the next line. It is just for safely
 // updating the version in our release process.
-def grpcVersion = '1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def grpcVersion = '1.54.2' // CURRENT_GRPC_VERSION
 def protobufVersion = '3.21.7'
 def protocVersion = protobufVersion
 

examples/example-gauth/pom.xml

@@ -6,13 +6,13 @@
   <packaging>jar</packaging>
   <!-- Feel free to delete the comment at the end of these lines. It is just
        for safely updating the version in our release process. -->
-  <version>1.54.0-SNAPSHOT</version><!-- CURRENT_GRPC_VERSION -->
+  <version>1.54.2</version><!-- CURRENT_GRPC_VERSION -->
   <name>example-gauth</name>
   <url>https://github.com/grpc/grpc-java</url>
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <grpc.version>1.54.0-SNAPSHOT</grpc.version><!-- CURRENT_GRPC_VERSION -->
+    <grpc.version>1.54.2</grpc.version><!-- CURRENT_GRPC_VERSION -->
     <protobuf.version>3.21.7</protobuf.version>
     <!-- required for jdk9 -->
     <maven.compiler.source>1.8</maven.compiler.source>

examples/example-gcp-observability/README.md

@@ -0,0 +1,39 @@
+gRPC GCP Observability Example
+================
+
+The GCP Observability example consists of a Hello World client and a Hello World server instrumented for logs, metrics and tracing. 
+
+__Please refer to Microservices Observability user guide for setup.__
+
+### Build the example
+
+Build the Observability client & server. From the `grpc-java/examples/example-gcp-observability`
+directory:
+```
+$ ../gradlew installDist
+```
+
+This creates the scripts `build/install/example-gcp-observability/bin/gcp-observability-client` and
+`build/install/example-gcp-observability/bin/gcp-observability-server`.
+
+### Run the example with configuration
+
+To use Observability, you should first setup and configure authorization as mentioned in the user guide. 
+
+You need to set the `GRPC_GCP_OBSERVABILITY_CONFIG_FILE` environment variable to point to the gRPC GCP Observability configuration file (preferred) or if that
+is not set then `GRPC_GCP_OBSERVABILITY_CONFIG` environment variable to gRPC GCP Observability configuration value. This is needed by both
+`build/install/example-gcp-observability/bin/gcp-observability-client` and
+`build/install/example-gcp-observability/bin/gcp-observability-server`.
+
+1. To start the observability-enabled example server on its default port of 50051, run:
+```
+$ export GRPC_GCP_OBSERVABILITY_CONFIG_FILE=src/main/resources/io/grpc/examples/gcpobservability/gcp_observability_server_config.json
+$ ./build/install/example-gcp-observability/bin/gcp-observability-server
+```
+
+2. In a different terminal window, run the observability-enabled example client:
+```
+$ export GRPC_GCP_OBSERVABILITY_CONFIG_FILE=src/main/resources/io/grpc/examples/gcpobservability/gcp_observability_client_config.json
+$ ./build/install/example-gcp-observability/bin/gcp-observability-client
+```
+

examples/example-gcp-observability/build.gradle

@@ -0,0 +1,68 @@
+plugins {
+    // Provide convenience executables for trying out the examples.
+    id 'application'
+    // ASSUMES GRADLE 5.6 OR HIGHER. Use plugin version 0.8.10 with earlier gradle versions
+    id 'com.google.protobuf' version '0.8.17'
+    // Generate IntelliJ IDEA's .idea & .iml project files
+    id 'idea'
+    id 'java'
+}
+
+repositories {
+    maven { // The google mirror is less flaky than mavenCentral()
+        url "https://maven-central.storage-download.googleapis.com/maven2/"
+    }
+    mavenCentral()
+    mavenLocal()
+}
+
+sourceCompatibility = 1.8
+targetCompatibility = 1.8
+
+// IMPORTANT: You probably want the non-SNAPSHOT version of gRPC. Make sure you
+// are looking at a tagged version of the example and not "master"!
+
+// Feel free to delete the comment at the next line. It is just for safely
+// updating the version in our release process.
+def grpcVersion = '1.54.2' // CURRENT_GRPC_VERSION
+def protocVersion = '3.21.7'
+
+dependencies {
+    implementation "io.grpc:grpc-protobuf:${grpcVersion}"
+    implementation "io.grpc:grpc-stub:${grpcVersion}"
+    implementation "io.grpc:grpc-gcp-observability:${grpcVersion}"
+    compileOnly "org.apache.tomcat:annotations-api:6.0.53"
+    runtimeOnly "io.grpc:grpc-netty-shaded:${grpcVersion}"
+}
+
+protobuf {
+    protoc { artifact = "com.google.protobuf:protoc:${protocVersion}" }
+    plugins {
+        grpc { artifact = "io.grpc:protoc-gen-grpc-java:${grpcVersion}" }
+    }
+    generateProtoTasks {
+        all()*.plugins { grpc {} }
+    }
+}
+
+startScripts.enabled = false
+
+task ObservabilityHelloWorldServer(type: CreateStartScripts) {
+    mainClass = 'io.grpc.examples.gcpobservability.GcpObservabilityServer'
+    applicationName = 'gcp-observability-server'
+    outputDir = new File(project.buildDir, 'tmp/scripts/' + name)
+    classpath = startScripts.classpath
+}
+
+task ObservabilityHelloWorldClient(type: CreateStartScripts) {
+    mainClass = 'io.grpc.examples.gcpobservability.GcpObservabilityClient'
+    applicationName = 'gcp-observability-client'
+    outputDir = new File(project.buildDir, 'tmp/scripts/' + name)
+    classpath = startScripts.classpath
+}
+
+applicationDistribution.into('bin') {
+    from(ObservabilityHelloWorldServer)
+    from(ObservabilityHelloWorldClient)
+    fileMode = 0755
+}

examples/example-gcp-observability/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'example-gcp-observability'

examples/example-gcp-observability/src/main/java/io/grpc/examples/gcpobservability/GcpObservabilityClient.java

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2023 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.
+ * You may obtain a copy of the License at
+ *
+ *     http://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 io.grpc.examples.gcpobservability;
+
+import io.grpc.Channel;
+import io.grpc.Grpc;
+import io.grpc.InsecureChannelCredentials;
+import io.grpc.ManagedChannel;
+import io.grpc.StatusRuntimeException;
+import io.grpc.examples.helloworld.GreeterGrpc;
+import io.grpc.examples.helloworld.HelloReply;
+import io.grpc.examples.helloworld.HelloRequest;
+import io.grpc.gcp.observability.GcpObservability;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * A simple observability client that requests a greeting from the {@link HelloWorldServer} and
+ * generates logs, metrics and traces based on the configuration.
+ */
+public class GcpObservabilityClient {
+  private static final Logger logger = Logger.getLogger(GcpObservabilityClient.class.getName());
+
+  private final GreeterGrpc.GreeterBlockingStub blockingStub;
+
+  /** Construct client for accessing HelloWorld server using the existing channel. */
+  public GcpObservabilityClient(Channel channel) {
+    blockingStub = GreeterGrpc.newBlockingStub(channel);
+  }
+
+  /** Say hello to server. */
+  public void greet(String name) {
+    logger.info("Will try to greet " + name + " ...");
+    HelloRequest request = HelloRequest.newBuilder().setName(name).build();
+    HelloReply response;
+    try {
+      response = blockingStub.sayHello(request);
+    } catch (StatusRuntimeException e) {
+      logger.log(Level.WARNING, "RPC failed: {0}", e.getStatus());
+      return;
+    }
+    logger.info("Greeting: " + response.getMessage());
+  }
+
+  /**
+   * Greet server. If provided, the first element of {@code args} is the name to use in the
+   * greeting. The second argument is the target server.
+   */
+  public static void main(String[] args) throws Exception {
+    String user = "world";
+    String target = "localhost:50051";
+    if (args.length > 0) {
+      if ("--help".equals(args[0])) {
+        System.err.println("Usage: [name [target]]");
+        System.err.println("");
+        System.err.println("  name    The name you wish to be greeted by. Defaults to " + user);
+        System.err.println("  target  The server to connect to. Defaults to " + target);
+        System.exit(1);
+      }
+      user = args[0];
+    }
+    if (args.length > 1) {
+      target = args[1];
+    }
+
+    // Initialize observability
+    try (GcpObservability observability = GcpObservability.grpcInit()) {
+      ManagedChannel channel = Grpc.newChannelBuilder(target, InsecureChannelCredentials.create())
+          .build();
+      try {
+        GcpObservabilityClient client = new GcpObservabilityClient(channel);
+        client.greet(user);
+      } finally {
+        channel.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
+      }
+    } // observability.close() called implicitly
+  }
+}

examples/example-gcp-observability/src/main/java/io/grpc/examples/gcpobservability/GcpObservabilityServer.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2023 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.
+ * You may obtain a copy of the License at
+ *
+ *     http://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 io.grpc.examples.gcpobservability;
+
+import io.grpc.Grpc;
+import io.grpc.InsecureServerCredentials;
+import io.grpc.Server;
+import io.grpc.examples.helloworld.GreeterGrpc;
+import io.grpc.examples.helloworld.HelloReply;
+import io.grpc.examples.helloworld.HelloRequest;
+import io.grpc.gcp.observability.GcpObservability;
+import io.grpc.stub.StreamObserver;
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Logger;
+
+/**
+ * Observability server that manages startup/shutdown of a {@code Greeter} server and generates
+ * logs, metrics and traces based on the configuration.
+ */
+public class GcpObservabilityServer {
+  private static final Logger logger = Logger.getLogger(GcpObservabilityServer.class.getName());
+
+  private Server server;
+
+  private void start() throws IOException {
+    int port = 50051;
+    server = Grpc.newServerBuilderForPort(port, InsecureServerCredentials.create())
+        .addService(new GreeterImpl())
+        .build()
+        .start();
+    logger.info("Server started, listening on " + port);
+  }
+
+  private void stop() throws InterruptedException {
+    if (server != null) {
+      server.shutdown().awaitTermination(30, TimeUnit.SECONDS);
+    }
+  }
+
+  private void blockUntilShutdown() throws InterruptedException {
+    if (server != null) {
+      server.awaitTermination();
+    }
+  }
+
+  /**
+   * Main launches the server from the command line.
+   */
+  public static void main(String[] args) throws IOException, InterruptedException {
+    // Initialize observability
+    GcpObservability observability = GcpObservability.grpcInit();
+    final GcpObservabilityServer server = new GcpObservabilityServer();
+    server.start();
+
+    Runtime.getRuntime().addShutdownHook(new Thread() {
+      @Override
+      public void run() {
+        System.err.println("*** shutting down gRPC server since JVM is shutting down");
+        try {
+          server.stop();
+        } catch (InterruptedException e) {
+          e.printStackTrace(System.err);
+        }
+        // Shut down observability
+        observability.close();
+        System.err.println("*** server shut down");
+      }
+    });
+
+    server.blockUntilShutdown();
+  }
+
+  static class GreeterImpl extends GreeterGrpc.GreeterImplBase {
+
+    @Override
+    public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
+      HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName()).build();
+      responseObserver.onNext(reply);
+      responseObserver.onCompleted();
+    }
+  }
+}

examples/example-gcp-observability/src/main/proto/helloworld/helloworld.proto

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2023 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.
+ * You may obtain a copy of the License at
+ *
+ *     http://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.
+ */
+syntax = "proto3";
+
+option java_multiple_files = true;
+option java_package = "io.grpc.examples.helloworld";
+option java_outer_classname = "HelloWorldProto";
+option objc_class_prefix = "HLW";
+
+package helloworld;
+
+// The greeting service definition.
+service Greeter {
+  // Sends a greeting
+  rpc SayHello (HelloRequest) returns (HelloReply) {}
+}
+
+// The request message containing the user's name.
+message HelloRequest {
+  string name = 1;
+}
+
+// The response message containing the greetings
+message HelloReply {
+  string message = 1;
+}

examples/example-gcp-observability/src/main/resources/io/grpc/examples/gcpobservability/gcp_observability_client_config.json

@@ -0,0 +1,17 @@
+{
+  "cloud_monitoring": {},
+  "cloud_trace": {
+    "sampling_rate": 1.0
+  },
+  "cloud_logging": {
+    "client_rpc_events": [{
+      "methods": ["helloworld.Greeter/*"]
+    }],
+    "server_rpc_events": [{
+      "methods": ["helloworld.Greeter/*"]
+    }]
+  },
+  "labels": {
+    "environment" : "example-client"
+  }
+}

examples/example-gcp-observability/src/main/resources/io/grpc/examples/gcpobservability/gcp_observability_server_config.json

@@ -0,0 +1,17 @@
+{
+  "cloud_monitoring": {},
+  "cloud_trace": {
+    "sampling_rate": 1.0
+  },
+  "cloud_logging": {
+    "client_rpc_events": [{
+      "methods": ["helloworld.Greeter/*"]
+    }],
+    "server_rpc_events": [{
+      "methods": ["helloworld.Greeter/*"]
+    }]
+  },
+  "labels": {
+    "environment" : "example-server"
+  }
+}

examples/example-hostname/build.gradle

@@ -21,7 +21,7 @@ targetCompatibility = 1.8
 
 // Feel free to delete the comment at the next line. It is just for safely
 // updating the version in our release process.
-def grpcVersion = '1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def grpcVersion = '1.54.2' // CURRENT_GRPC_VERSION
 def protobufVersion = '3.21.7'
 
 dependencies {

examples/example-hostname/pom.xml

@@ -6,13 +6,13 @@
   <packaging>jar</packaging>
   <!-- Feel free to delete the comment at the end of these lines. It is just
        for safely updating the version in our release process. -->
-  <version>1.54.0-SNAPSHOT</version><!-- CURRENT_GRPC_VERSION -->
+  <version>1.54.2</version><!-- CURRENT_GRPC_VERSION -->
   <name>example-hostname</name>
   <url>https://github.com/grpc/grpc-java</url>
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <grpc.version>1.54.0-SNAPSHOT</grpc.version><!-- CURRENT_GRPC_VERSION -->
+    <grpc.version>1.54.2</grpc.version><!-- CURRENT_GRPC_VERSION -->
     <protoc.version>3.21.7</protoc.version>
     <!-- required for jdk9 -->
     <maven.compiler.source>1.8</maven.compiler.source>

examples/example-jwt-auth/build.gradle

@@ -22,7 +22,7 @@ targetCompatibility = 1.8
 
 // Feel free to delete the comment at the next line. It is just for safely
 // updating the version in our release process.
-def grpcVersion = '1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def grpcVersion = '1.54.2' // CURRENT_GRPC_VERSION
 def protobufVersion = '3.21.7'
 def protocVersion = protobufVersion
 

examples/example-jwt-auth/pom.xml

@@ -7,13 +7,13 @@
   <packaging>jar</packaging>
   <!-- Feel free to delete the comment at the end of these lines. It is just
        for safely updating the version in our release process. -->
-  <version>1.54.0-SNAPSHOT</version><!-- CURRENT_GRPC_VERSION -->
+  <version>1.54.2</version><!-- CURRENT_GRPC_VERSION -->
   <name>example-jwt-auth</name>
   <url>https://github.com/grpc/grpc-java</url>
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <grpc.version>1.54.0-SNAPSHOT</grpc.version><!-- CURRENT_GRPC_VERSION -->
+    <grpc.version>1.54.2</grpc.version><!-- CURRENT_GRPC_VERSION -->
     <protobuf.version>3.21.7</protobuf.version>
     <protoc.version>3.21.7</protoc.version>
     <!-- required for jdk9 -->

examples/example-orca/build.gradle

@@ -17,7 +17,7 @@ repositories {
 sourceCompatibility = 1.8
 targetCompatibility = 1.8
 
-def grpcVersion = '1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def grpcVersion = '1.54.2' // CURRENT_GRPC_VERSION
 def protocVersion = '3.21.7'
 
 dependencies {

examples/example-servlet/build.gradle

@@ -15,7 +15,7 @@ repositories {
 sourceCompatibility = 1.8
 targetCompatibility = 1.8
 
-def grpcVersion = '1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def grpcVersion = '1.54.2' // CURRENT_GRPC_VERSION
 def protocVersion = '3.21.7'
 
 dependencies {

examples/example-tls/build.gradle

@@ -23,7 +23,7 @@ targetCompatibility = 1.8
 
 // Feel free to delete the comment at the next line. It is just for safely
 // updating the version in our release process.
-def grpcVersion = '1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def grpcVersion = '1.54.2' // CURRENT_GRPC_VERSION
 def protocVersion = '3.21.7'
 
 dependencies {

examples/example-tls/pom.xml

@@ -6,13 +6,13 @@
   <packaging>jar</packaging>
   <!-- Feel free to delete the comment at the end of these lines. It is just
        for safely updating the version in our release process. -->
-  <version>1.54.0-SNAPSHOT</version><!-- CURRENT_GRPC_VERSION -->
+  <version>1.54.2</version><!-- CURRENT_GRPC_VERSION -->
   <name>example-tls</name>
   <url>https://github.com/grpc/grpc-java</url>
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <grpc.version>1.54.0-SNAPSHOT</grpc.version><!-- CURRENT_GRPC_VERSION -->
+    <grpc.version>1.54.2</grpc.version><!-- CURRENT_GRPC_VERSION -->
     <protoc.version>3.21.7</protoc.version>
     <netty.tcnative.version>2.0.56.Final</netty.tcnative.version>
     <!-- required for jdk9 -->

examples/example-xds/build.gradle

@@ -22,7 +22,7 @@ targetCompatibility = 1.8
 
 // Feel free to delete the comment at the next line. It is just for safely
 // updating the version in our release process.
-def grpcVersion = '1.54.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def grpcVersion = '1.54.2' // CURRENT_GRPC_VERSION
 def nettyTcNativeVersion = '2.0.56.Final'
 def protocVersion = '3.21.7'
 

examples/pom.xml

@@ -6,13 +6,13 @@
   <packaging>jar</packaging>
   <!-- Feel free to delete the comment at the end of these lines. It is just
        for safely updating the version in our release process. -->
-  <version>1.54.0-SNAPSHOT</version><!-- CURRENT_GRPC_VERSION -->
+  <version>1.54.2</version><!-- CURRENT_GRPC_VERSION -->
   <name>examples</name>
   <url>https://github.com/grpc/grpc-java</url>
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <grpc.version>1.54.0-SNAPSHOT</grpc.version><!-- CURRENT_GRPC_VERSION -->
+    <grpc.version>1.54.2</grpc.version><!-- CURRENT_GRPC_VERSION -->
     <protobuf.version>3.21.7</protobuf.version>
     <protoc.version>3.21.7</protoc.version>
     <!-- required for JDK 8 -->

gcp-observability/build.gradle

@@ -20,11 +20,13 @@ tasks.named("compileJava").configure {
 }
 
 dependencies {
-    def cloudLoggingVersion = '3.6.1'
+    def cloudLoggingVersion = '3.14.5'
 
     annotationProcessor libraries.auto.value
     api project(':grpc-api')
-    
+
+    // TODO(dnvindhya): Prefer using our own libraries, update the dependencies
+    //  in gradle/libs.versions instead
     implementation project(':grpc-protobuf'),
             project(':grpc-stub'),
             project(':grpc-alts'),
@@ -35,12 +37,10 @@ dependencies {
             libraries.opencensus.exporter.trace.stackdriver,
             project(':grpc-xds'), // Align grpc versions
             project(':grpc-services'), // Align grpc versions
-            libraries.animalsniffer.annotations, // Prefer our version
-            libraries.google.auth.credentials, // Prefer our version
-            libraries.protobuf.java.util, // Prefer our version
-            libraries.gson, // Prefer our version
-            libraries.perfmark.api, // Prefer our version
-            libraries.re2j, // Prefer our version
+            ('com.google.protobuf:protobuf-java:3.21.12'),
+            ('com.google.api.grpc:proto-google-common-protos:2.14.2'),
+            ('com.google.auth:google-auth-library-oauth2-http:1.16.0'),
+            ('io.opencensus:opencensus-api:0.31.1'),
             ('com.google.guava:guava:31.1-jre')
 
     runtimeOnly libraries.opencensus.impl

gcp-observability/interop/src/main/java/io/grpc/gcp/observability/interop/TestServiceInterop.java

@@ -20,7 +20,6 @@ import io.grpc.gcp.observability.GcpObservability;
 import io.grpc.testing.integration.TestServiceClient;
 import io.grpc.testing.integration.TestServiceServer;
 import java.util.Arrays;
-import java.util.concurrent.TimeUnit;
 
 /**
  * Combined interop client and server for observability testing.
@@ -47,11 +46,6 @@ public final class TestServiceInterop {
       } else {
         TestServiceServer.main(args);
       }
-      // TODO(stanleycheung): remove this once the observability exporter plugin is able to
-      //                      gracefully flush observability data to cloud at shutdown
-      final int o11yCloseSleepSeconds = 65;
-      System.out.println("Sleeping " + o11yCloseSleepSeconds + " seconds before exiting");
-      Thread.sleep(TimeUnit.MILLISECONDS.convert(o11yCloseSleepSeconds, TimeUnit.SECONDS));
     }
   }
 

gcp-observability/src/main/java/io/grpc/gcp/observability/GcpObservability.java

@@ -21,7 +21,6 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableSet;
 import io.grpc.ClientInterceptor;
-import io.grpc.ExperimentalApi;
 import io.grpc.InternalGlobalInterceptors;
 import io.grpc.ManagedChannelProvider.ProviderNotFoundException;
 import io.grpc.ServerInterceptor;
@@ -36,6 +35,7 @@ import io.grpc.gcp.observability.interceptors.InternalLoggingServerInterceptor;
 import io.grpc.gcp.observability.interceptors.LogHelper;
 import io.grpc.gcp.observability.logging.GcpLogSink;
 import io.grpc.gcp.observability.logging.Sink;
+import io.grpc.gcp.observability.logging.TraceLoggingHelper;
 import io.opencensus.common.Duration;
 import io.opencensus.contrib.grpc.metrics.RpcViewConstants;
 import io.opencensus.exporter.stats.stackdriver.StackdriverStatsConfiguration;
@@ -50,17 +50,30 @@ import io.opencensus.trace.AttributeValue;
 import io.opencensus.trace.Tracing;
 import io.opencensus.trace.config.TraceConfig;
 import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.security.SecureRandom;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 import java.util.stream.Collectors;
 
 /** The main class for gRPC Google Cloud Platform Observability features. */
-@ExperimentalApi("https://github.com/grpc/grpc-java/issues/8869")
 public final class GcpObservability implements AutoCloseable {
+
+  private static final Logger logger = Logger.getLogger(GcpObservability.class.getName());
   private static final int METRICS_EXPORT_INTERVAL = 30;
-  private static final ImmutableSet<String> SERVICES_TO_EXCLUDE = ImmutableSet.of(
+
+  static final String DEFAULT_METRIC_CUSTOM_TAG_KEY = "opencensus_task";
+  @VisibleForTesting
+  static final ImmutableSet<String> SERVICES_TO_EXCLUDE = ImmutableSet.of(
       "google.logging.v2.LoggingServiceV2", "google.monitoring.v3.MetricService",
       "google.devtools.cloudtrace.v2.TraceService");
+
   private static GcpObservability instance = null;
   private final Sink sink;
   private final ObservabilityConfig config;
@@ -75,11 +88,11 @@ public final class GcpObservability implements AutoCloseable {
    */
   public static synchronized GcpObservability grpcInit() throws IOException {
     if (instance == null) {
-      GlobalLocationTags globalLocationTags = new GlobalLocationTags();
       ObservabilityConfigImpl observabilityConfig = ObservabilityConfigImpl.getInstance();
-      Sink sink = new GcpLogSink(observabilityConfig.getProjectId(),
-          globalLocationTags.getLocationTags(), observabilityConfig.getCustomTags(),
-          SERVICES_TO_EXCLUDE);
+      TraceLoggingHelper traceLoggingHelper = new TraceLoggingHelper(
+          observabilityConfig.getProjectId());
+      Sink sink = new GcpLogSink(observabilityConfig.getProjectId(), observabilityConfig,
+          SERVICES_TO_EXCLUDE, traceLoggingHelper);
       LogHelper helper = new LogHelper(sink);
       ConfigFilterHelper configFilterHelper = ConfigFilterHelper.getInstance(observabilityConfig);
       instance = grpcInit(sink, observabilityConfig,
@@ -113,6 +126,16 @@ public final class GcpObservability implements AutoCloseable {
         throw new IllegalStateException("GcpObservability already closed!");
       }
       sink.close();
+      if (config.isEnableCloudMonitoring() || config.isEnableCloudTracing()) {
+        try {
+          // Sleeping before shutdown to ensure all metrics and traces are flushed
+          Thread.sleep(
+              TimeUnit.MILLISECONDS.convert(2 * METRICS_EXPORT_INTERVAL, TimeUnit.SECONDS));
+        } catch (InterruptedException e) {
+          Thread.currentThread().interrupt();
+          logger.log(Level.SEVERE, "Caught exception during sleep", e);
+        }
+      }
       instance = null;
     }
   }
@@ -128,14 +151,14 @@ public final class GcpObservability implements AutoCloseable {
     }
     if (config.isEnableCloudMonitoring()) {
       clientInterceptors.add(getConditionalInterceptor(
-          InternalCensusStatsAccessor.getClientInterceptor(true, true, true, true)));
+          InternalCensusStatsAccessor.getClientInterceptor(true, true, false, true)));
       tracerFactories.add(
-          InternalCensusStatsAccessor.getServerStreamTracerFactory(true, true, true));
+          InternalCensusStatsAccessor.getServerStreamTracerFactory(true, true, false));
     }
     if (config.isEnableCloudTracing()) {
       clientInterceptors.add(
-          getConditionalInterceptor(InternalCensusTracingAccessor.getClientInterceptor(false)));
-      tracerFactories.add(InternalCensusTracingAccessor.getServerStreamTracerFactory(false));
+          getConditionalInterceptor(InternalCensusTracingAccessor.getClientInterceptor()));
+      tracerFactories.add(InternalCensusTracingAccessor.getServerStreamTracerFactory());
     }
 
     InternalGlobalInterceptors.setInterceptorsTracers(
@@ -180,12 +203,17 @@ public final class GcpObservability implements AutoCloseable {
       if (projectId != null) {
         statsConfigurationBuilder.setProjectId(projectId);
       }
+      Map<LabelKey, LabelValue> constantLabels = new HashMap<>();
+      constantLabels.put(
+          LabelKey.create(DEFAULT_METRIC_CUSTOM_TAG_KEY, DEFAULT_METRIC_CUSTOM_TAG_KEY),
+          LabelValue.create(generateDefaultMetricTagValue()));
       if (customTags != null) {
-        Map<LabelKey, LabelValue> constantLabels = customTags.entrySet().stream()
-            .collect(Collectors.toMap(e -> LabelKey.create(e.getKey(), e.getKey()),
-                e -> LabelValue.create(e.getValue())));
-        statsConfigurationBuilder.setConstantLabels(constantLabels);
+        for (Map.Entry<String, String> mapEntry : customTags.entrySet()) {
+          constantLabels.putIfAbsent(LabelKey.create(mapEntry.getKey(), mapEntry.getKey()),
+              LabelValue.create(mapEntry.getValue()));
+        }
       }
+      statsConfigurationBuilder.setConstantLabels(constantLabels);
       statsConfigurationBuilder.setExportInterval(Duration.create(METRICS_EXPORT_INTERVAL, 0));
       StackdriverStatsExporter.createAndRegister(statsConfigurationBuilder.build());
     }
@@ -209,6 +237,20 @@ public final class GcpObservability implements AutoCloseable {
     }
   }
 
+  private static String generateDefaultMetricTagValue() {
+    final String jvmName = ManagementFactory.getRuntimeMXBean().getName();
+    if (jvmName.indexOf('@') < 1) {
+      String hostname = "localhost";
+      try {
+        hostname = InetAddress.getLocalHost().getHostName();
+      } catch (UnknownHostException e) {
+        logger.log(Level.INFO, "Unable to get the hostname.", e);
+      }
+      return "java-" + new SecureRandom().nextInt() + "@" + hostname;
+    }
+    return "java-" + jvmName;
+  }
+
   private GcpObservability(
       Sink sink,
       ObservabilityConfig config) {

gcp-observability/src/main/java/io/grpc/gcp/observability/GlobalLocationTags.java

@@ -1,148 +0,0 @@
-/*
- * Copyright 2022 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.
- * You may obtain a copy of the License at
- *
- *     http://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 io.grpc.gcp.observability;
-
-import com.google.api.client.http.HttpTransport;
-import com.google.api.client.http.javanet.NetHttpTransport;
-import com.google.api.client.util.Strings;
-import com.google.auth.http.HttpTransportFactory;
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Charsets;
-import com.google.common.collect.ImmutableMap;
-import java.io.IOException;
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.nio.file.Paths;
-import java.util.Map;
-import java.util.Scanner;
-import java.util.function.Function;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
-/** A container of all global location tags used for observability. */
-final class GlobalLocationTags {
-  private static final Logger logger = Logger.getLogger(GlobalLocationTags.class.getName());
-
-  private final Map<String, String> locationTags;
-
-  GlobalLocationTags() {
-    ImmutableMap.Builder<String, String> locationTagsBuilder = ImmutableMap.builder();
-    populate(locationTagsBuilder);
-    locationTags = locationTagsBuilder.buildOrThrow();
-  }
-
-  private static String applyTrim(String value) {
-    if (!Strings.isNullOrEmpty(value)) {
-      value = value.trim();
-    }
-    return value;
-  }
-
-  Map<String, String> getLocationTags() {
-    return locationTags;
-  }
-
-  @VisibleForTesting
-  static void populateFromMetadataServer(ImmutableMap.Builder<String, String> locationTags) {
-    MetadataConfig metadataConfig = new MetadataConfig(new DefaultHttpTransportFactory());
-    metadataConfig.init();
-    locationTags.putAll(metadataConfig.getAllValues());
-  }
-
-  @VisibleForTesting
-  static void populateFromKubernetesValues(ImmutableMap.Builder<String, String> locationTags,
-      String namespaceFile,
-      String hostnameFile, String cgroupFile) {
-    // namespace name: contents of file /var/run/secrets/kubernetes.io/serviceaccount/namespace
-    populateFromFileContents(locationTags, "namespace_name",
-        namespaceFile, GlobalLocationTags::applyTrim);
-
-    // pod_name: hostname i.e. contents of /etc/hostname
-    populateFromFileContents(locationTags, "pod_name", hostnameFile,
-        GlobalLocationTags::applyTrim);
-
-    // container_id: parsed from /proc/self/cgroup . Note: only works for Linux-based containers
-    populateFromFileContents(locationTags, "container_id", cgroupFile,
-        (value) -> getContainerIdFromFileContents(value));
-  }
-
-  @VisibleForTesting
-  static void populateFromFileContents(ImmutableMap.Builder<String, String> locationTags,
-      String key, String filePath, Function<String, String> parser) {
-    String value = parser.apply(readFileContents(filePath));
-    if (value != null) {
-      locationTags.put(key, value);
-    }
-  }
-
-  /**
-   * Parse from a line such as this.
-   * 1:name=systemd:/kubepods/burstable/podf5143dd2/de67c4419b20924eaa141813
-   *
-   * @param value file contents
-   * @return container-id parsed ("podf5143dd2/de67c4419b20924eaa141813" from the above snippet)
-   */
-  @VisibleForTesting static String getContainerIdFromFileContents(String value) {
-    if (value != null) {
-      try (Scanner scanner = new Scanner(value)) {
-        while (scanner.hasNextLine()) {
-          String line = scanner.nextLine();
-          String[] tokens = line.split(":");
-          if (tokens.length == 3 && tokens[2].startsWith("/kubepods/burstable/")) {
-            tokens = tokens[2].split("/");
-            if (tokens.length == 5) {
-              return tokens[4];
-            }
-          }
-        }
-      }
-    }
-    return null;
-  }
-
-  private static String readFileContents(String file) {
-    Path fileName = Paths.get(file);
-    if (Files.isReadable(fileName)) {
-      try {
-        byte[] bytes = Files.readAllBytes(fileName);
-        return new String(bytes, Charsets.US_ASCII);
-      } catch (IOException e) {
-        logger.log(Level.FINE, "Reading file:" + file, e);
-      }
-    } else {
-      logger.log(Level.FINE, "File:" + file + " is not readable (or missing?)");
-    }
-    return null;
-  }
-
-  static void populate(ImmutableMap.Builder<String, String> locationTags) {
-    populateFromMetadataServer(locationTags);
-    populateFromKubernetesValues(locationTags,
-        "/var/run/secrets/kubernetes.io/serviceaccount/namespace",
-        "/etc/hostname", "/proc/self/cgroup");
-  }
-
-  private static class DefaultHttpTransportFactory implements HttpTransportFactory {
-
-    private static final HttpTransport netHttpTransport = new NetHttpTransport();
-
-    @Override
-    public HttpTransport create() {
-      return netHttpTransport;
-    }
-  }
-}

gcp-observability/src/main/java/io/grpc/gcp/observability/MetadataConfig.java

@@ -1,107 +0,0 @@
-/*
- * Copyright 2022 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.
- * You may obtain a copy of the License at
- *
- *     http://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 io.grpc.gcp.observability;
-
-import com.google.api.client.http.GenericUrl;
-import com.google.api.client.http.HttpHeaders;
-import com.google.api.client.http.HttpRequest;
-import com.google.api.client.http.HttpRequestFactory;
-import com.google.api.client.http.HttpResponse;
-import com.google.api.client.http.HttpStatusCodes;
-import com.google.api.client.http.HttpTransport;
-import com.google.auth.http.HttpTransportFactory;
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.collect.ImmutableMap;
-import java.io.IOException;
-import java.io.InputStream;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
-/** Class to read Google Metadata Server values. */
-final class MetadataConfig {
-  private static final Logger logger = Logger.getLogger(MetadataConfig.class.getName());
-
-  private static final int TIMEOUT_MS = 5000;
-  private static final String METADATA_URL = "http://metadata.google.internal/computeMetadata/v1/";
-  private HttpRequestFactory requestFactory;
-  private HttpTransportFactory transportFactory;
-
-  @VisibleForTesting public MetadataConfig(HttpTransportFactory transportFactory) {
-    this.transportFactory = transportFactory;
-
-  }
-
-  void init() {
-    HttpTransport httpTransport = transportFactory.create();
-    requestFactory = httpTransport.createRequestFactory();
-  }
-
-  /** gets all the values from the MDS we need to set in our logging tags. */
-  ImmutableMap<String, String> getAllValues() {
-    ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();
-    //addValueFor(builder, "instance/hostname", "GCE_INSTANCE_HOSTNAME");
-    addValueFor(builder, "instance/id", "gke_node_id");
-    //addValueFor(builder, "instance/zone", "GCE_INSTANCE_ZONE");
-    addValueFor(builder, "project/project-id", "project_id");
-    addValueFor(builder, "project/numeric-project-id", "project_numeric_id");
-    addValueFor(builder, "instance/attributes/cluster-name", "cluster_name");
-    addValueFor(builder, "instance/attributes/cluster-uid", "cluster_uid");
-    addValueFor(builder, "instance/attributes/cluster-location", "location");
-    try {
-      requestFactory.getTransport().shutdown();
-    } catch (IOException e) {
-      logger.log(Level.FINE, "Calling HttpTransport.shutdown()", e);
-    }
-    return builder.buildOrThrow();
-  }
-
-  void addValueFor(ImmutableMap.Builder<String, String> builder, String attribute, String key) {
-    try {
-      String value = getAttribute(attribute);
-      if (value != null) {
-        builder.put(key, value);
-      }
-    } catch (IOException e) {
-      logger.log(Level.FINE, "Calling getAttribute('" + attribute +  "')", e);
-    }
-  }
-
-  String getAttribute(String attributeName) throws IOException {
-    GenericUrl url = new GenericUrl(METADATA_URL + attributeName);
-    HttpRequest request = requestFactory.buildGetRequest(url);
-    request = request.setReadTimeout(TIMEOUT_MS);
-    request = request.setConnectTimeout(TIMEOUT_MS);
-    request = request.setHeaders(new HttpHeaders().set("Metadata-Flavor", "Google"));
-    HttpResponse response = null;
-    try {
-      response = request.execute();
-      if (response.getStatusCode() == HttpStatusCodes.STATUS_CODE_OK) {
-        InputStream stream = response.getContent();
-        if (stream != null) {
-          byte[] bytes = new byte[stream.available()];
-          stream.read(bytes);
-          return new String(bytes, response.getContentCharset());
-        }
-      }
-    } finally {
-      if (response != null) {
-        response.disconnect();
-      }
-    }
-    return null;
-  }
-}

gcp-observability/src/main/java/io/grpc/gcp/observability/interceptors/InternalLoggingChannelInterceptor.java

@@ -16,6 +16,8 @@
 
 package io.grpc.gcp.observability.interceptors;
 
+import static io.grpc.census.internal.ObservabilityCensusConstants.CLIENT_TRACE_SPAN_CONTEXT_KEY;
+
 import com.google.protobuf.Duration;
 import com.google.protobuf.util.Durations;
 import io.grpc.CallOptions;
@@ -33,6 +35,7 @@ import io.grpc.Status;
 import io.grpc.gcp.observability.interceptors.ConfigFilterHelper.FilterParams;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventLogger;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventType;
+import io.opencensus.trace.SpanContext;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicLong;
@@ -92,6 +95,7 @@ public final class InternalLoggingChannelInterceptor implements ClientIntercepto
     // Get the stricter deadline to calculate the timeout once the call starts
     final Deadline deadline = LogHelper.min(callOptions.getDeadline(),
         Context.current().getDeadline());
+    final SpanContext clientSpanContext = callOptions.getOption(CLIENT_TRACE_SPAN_CONTEXT_KEY);
 
     FilterParams filterParams = filterHelper.logRpcMethod(method.getFullMethodName(), true);
     if (!filterParams.log()) {
@@ -122,7 +126,8 @@ public final class InternalLoggingChannelInterceptor implements ClientIntercepto
               maxHeaderBytes,
               EventLogger.CLIENT,
               callId,
-              null);
+              null,
+              clientSpanContext);
         } catch (Exception e) {
           // Catching generic exceptions instead of specific ones for all the events.
           // This way we can catch both expected and unexpected exceptions instead of re-throwing
@@ -148,7 +153,8 @@ public final class InternalLoggingChannelInterceptor implements ClientIntercepto
                       message,
                       maxMessageBytes,
                       EventLogger.CLIENT,
-                      callId);
+                      callId,
+                      clientSpanContext);
                 } catch (Exception e) {
                   logger.log(Level.SEVERE, "Unable to log response message", e);
                 }
@@ -168,7 +174,8 @@ public final class InternalLoggingChannelInterceptor implements ClientIntercepto
                       maxHeaderBytes,
                       EventLogger.CLIENT,
                       callId,
-                      LogHelper.getPeerAddress(getAttributes()));
+                      LogHelper.getPeerAddress(getAttributes()),
+                      clientSpanContext);
                 } catch (Exception e) {
                   logger.log(Level.SEVERE, "Unable to log response header", e);
                 }
@@ -189,7 +196,8 @@ public final class InternalLoggingChannelInterceptor implements ClientIntercepto
                       maxHeaderBytes,
                       EventLogger.CLIENT,
                       callId,
-                      LogHelper.getPeerAddress(getAttributes()));
+                      LogHelper.getPeerAddress(getAttributes()),
+                      clientSpanContext);
                 } catch (Exception e) {
                   logger.log(Level.SEVERE, "Unable to log trailer", e);
                 }
@@ -212,7 +220,8 @@ public final class InternalLoggingChannelInterceptor implements ClientIntercepto
               message,
               maxMessageBytes,
               EventLogger.CLIENT,
-              callId);
+              callId,
+              clientSpanContext);
         } catch (Exception e) {
           logger.log(Level.SEVERE, "Unable to log request message", e);
         }
@@ -229,7 +238,8 @@ public final class InternalLoggingChannelInterceptor implements ClientIntercepto
               methodName,
               authority,
               EventLogger.CLIENT,
-              callId);
+              callId,
+              clientSpanContext);
         } catch (Exception e) {
           logger.log(Level.SEVERE, "Unable to log half close", e);
         }
@@ -246,7 +256,8 @@ public final class InternalLoggingChannelInterceptor implements ClientIntercepto
               methodName,
               authority,
               EventLogger.CLIENT,
-              callId);
+              callId,
+              clientSpanContext);
         } catch (Exception e) {
           logger.log(Level.SEVERE, "Unable to log cancel", e);
         }

gcp-observability/src/main/java/io/grpc/gcp/observability/interceptors/InternalLoggingServerInterceptor.java

@@ -31,6 +31,9 @@ import io.grpc.Status;
 import io.grpc.gcp.observability.interceptors.ConfigFilterHelper.FilterParams;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventLogger;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventType;
+import io.opencensus.trace.Span;
+import io.opencensus.trace.SpanContext;
+import io.opencensus.trace.unsafe.ContextHandleUtils;
 import java.net.SocketAddress;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
@@ -91,6 +94,8 @@ public final class InternalLoggingServerInterceptor implements ServerInterceptor
     Deadline deadline = Context.current().getDeadline();
     final Duration timeout = deadline == null ? null
         : Durations.fromNanos(deadline.timeRemaining(TimeUnit.NANOSECONDS));
+    Span span = ContextHandleUtils.getValue(ContextHandleUtils.currentContext());
+    final SpanContext serverSpanContext = span == null ? SpanContext.INVALID : span.getContext();
 
     FilterParams filterParams =
         filterHelper.logRpcMethod(call.getMethodDescriptor().getFullMethodName(), false);
@@ -113,7 +118,8 @@ public final class InternalLoggingServerInterceptor implements ServerInterceptor
           maxHeaderBytes,
           EventLogger.SERVER,
           callId,
-          peerAddress);
+          peerAddress,
+          serverSpanContext);
     } catch (Exception e) {
       // Catching generic exceptions instead of specific ones for all the events.
       // This way we can catch both expected and unexpected exceptions instead of re-throwing
@@ -139,7 +145,8 @@ public final class InternalLoggingServerInterceptor implements ServerInterceptor
                   maxHeaderBytes,
                   EventLogger.SERVER,
                   callId,
-                  null);
+                  null,
+                  serverSpanContext);
             } catch (Exception e) {
               logger.log(Level.SEVERE, "Unable to log response header", e);
             }
@@ -160,7 +167,8 @@ public final class InternalLoggingServerInterceptor implements ServerInterceptor
                   message,
                   maxMessageBytes,
                   EventLogger.SERVER,
-                  callId);
+                  callId,
+                  serverSpanContext);
             } catch (Exception e) {
               logger.log(Level.SEVERE, "Unable to log response message", e);
             }
@@ -181,7 +189,8 @@ public final class InternalLoggingServerInterceptor implements ServerInterceptor
                   maxHeaderBytes,
                   EventLogger.SERVER,
                   callId,
-                  null);
+                  null,
+                  serverSpanContext);
             } catch (Exception e) {
               logger.log(Level.SEVERE, "Unable to log trailer", e);
             }
@@ -206,7 +215,8 @@ public final class InternalLoggingServerInterceptor implements ServerInterceptor
               message,
               maxMessageBytes,
               EventLogger.SERVER,
-              callId);
+              callId,
+              serverSpanContext);
         } catch (Exception e) {
           logger.log(Level.SEVERE, "Unable to log request message", e);
         }
@@ -223,7 +233,8 @@ public final class InternalLoggingServerInterceptor implements ServerInterceptor
               methodName,
               authority,
               EventLogger.SERVER,
-              callId);
+              callId,
+              serverSpanContext);
         } catch (Exception e) {
           logger.log(Level.SEVERE, "Unable to log half close", e);
         }
@@ -240,7 +251,8 @@ public final class InternalLoggingServerInterceptor implements ServerInterceptor
               methodName,
               authority,
               EventLogger.SERVER,
-              callId);
+              callId,
+              serverSpanContext);
         } catch (Exception e) {
           logger.log(Level.SEVERE, "Unable to log cancel", e);
         }

gcp-observability/src/main/java/io/grpc/gcp/observability/interceptors/LogHelper.java

@@ -23,6 +23,7 @@ import static io.grpc.InternalMetadata.BASE64_ENCODING_OMIT_PADDING;
 import com.google.common.base.Joiner;
 import com.google.protobuf.ByteString;
 import com.google.protobuf.Duration;
+import com.google.rpc.Code;
 import io.grpc.Attributes;
 import io.grpc.Deadline;
 import io.grpc.Grpc;
@@ -35,6 +36,7 @@ import io.grpc.observabilitylog.v1.GrpcLogRecord;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventLogger;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventType;
 import io.grpc.observabilitylog.v1.Payload;
+import io.opencensus.trace.SpanContext;
 import java.net.Inet4Address;
 import java.net.Inet6Address;
 import java.net.InetAddress;
@@ -87,7 +89,8 @@ public class LogHelper {
       GrpcLogRecord.EventLogger eventLogger,
       String callId,
       // null on client side
-      @Nullable SocketAddress peerAddress) {
+      @Nullable SocketAddress peerAddress,
+      SpanContext spanContext) {
     checkNotNull(serviceName, "serviceName");
     checkNotNull(methodName, "methodName");
     checkNotNull(authority, "authority");
@@ -113,7 +116,7 @@ public class LogHelper {
     if (peerAddress != null) {
       logEntryBuilder.setPeer(socketAddressToProto(peerAddress));
     }
-    sink.write(logEntryBuilder.build());
+    sink.write(logEntryBuilder.build(), spanContext);
   }
 
   /**
@@ -128,7 +131,8 @@ public class LogHelper {
       int maxHeaderBytes,
       GrpcLogRecord.EventLogger eventLogger,
       String callId,
-      @Nullable SocketAddress peerAddress) {
+      @Nullable SocketAddress peerAddress,
+      SpanContext spanContext) {
     checkNotNull(serviceName, "serviceName");
     checkNotNull(methodName, "methodName");
     checkNotNull(authority, "authority");
@@ -154,7 +158,7 @@ public class LogHelper {
     if (peerAddress != null) {
       logEntryBuilder.setPeer(socketAddressToProto(peerAddress));
     }
-    sink.write(logEntryBuilder.build());
+    sink.write(logEntryBuilder.build(), spanContext);
   }
 
   /**
@@ -170,7 +174,8 @@ public class LogHelper {
       int maxHeaderBytes,
       GrpcLogRecord.EventLogger eventLogger,
       String callId,
-      @Nullable SocketAddress peerAddress) {
+      @Nullable SocketAddress peerAddress,
+      SpanContext spanContext) {
     checkNotNull(serviceName, "serviceName");
     checkNotNull(methodName, "methodName");
     checkNotNull(authority, "authority");
@@ -182,7 +187,7 @@ public class LogHelper {
 
     PayloadBuilderHelper<Payload.Builder> pair =
         createMetadataProto(metadata, maxHeaderBytes);
-    pair.payloadBuilder.setStatusCode(status.getCode().value());
+    pair.payloadBuilder.setStatusCode(Code.forNumber(status.getCode().value()));
     String statusDescription = status.getDescription();
     if (statusDescription != null) {
       pair.payloadBuilder.setStatusMessage(statusDescription);
@@ -204,7 +209,7 @@ public class LogHelper {
     if (peerAddress != null) {
       logEntryBuilder.setPeer(socketAddressToProto(peerAddress));
     }
-    sink.write(logEntryBuilder.build());
+    sink.write(logEntryBuilder.build(), spanContext);
   }
 
   /**
@@ -219,7 +224,8 @@ public class LogHelper {
       T message,
       int maxMessageBytes,
       EventLogger eventLogger,
-      String callId) {
+      String callId,
+      SpanContext spanContext) {
     checkNotNull(serviceName, "serviceName");
     checkNotNull(methodName, "methodName");
     checkNotNull(authority, "authority");
@@ -259,7 +265,7 @@ public class LogHelper {
       logEntryBuilder.setPayload(pair.payloadBuilder)
           .setPayloadTruncated(pair.truncated);
     }
-    sink.write(logEntryBuilder.build());
+    sink.write(logEntryBuilder.build(), spanContext);
   }
 
   /**
@@ -271,7 +277,8 @@ public class LogHelper {
       String methodName,
       String authority,
       GrpcLogRecord.EventLogger eventLogger,
-      String callId) {
+      String callId,
+      SpanContext spanContext) {
     checkNotNull(serviceName, "serviceName");
     checkNotNull(methodName, "methodName");
     checkNotNull(authority, "authority");
@@ -285,7 +292,7 @@ public class LogHelper {
         .setType(EventType.CLIENT_HALF_CLOSE)
         .setLogger(eventLogger)
         .setCallId(callId);
-    sink.write(logEntryBuilder.build());
+    sink.write(logEntryBuilder.build(), spanContext);
   }
 
   /**
@@ -297,7 +304,8 @@ public class LogHelper {
       String methodName,
       String authority,
       GrpcLogRecord.EventLogger eventLogger,
-      String callId) {
+      String callId,
+      SpanContext spanContext) {
     checkNotNull(serviceName, "serviceName");
     checkNotNull(methodName, "methodName");
     checkNotNull(authority, "authority");
@@ -311,7 +319,7 @@ public class LogHelper {
         .setType(EventType.CANCEL)
         .setLogger(eventLogger)
         .setCallId(callId);
-    sink.write(logEntryBuilder.build());
+    sink.write(logEntryBuilder.build(), spanContext);
   }
 
   // TODO(DNVindhya): Evaluate if we need following clause for metadata logging in GcpObservability
@@ -404,10 +412,10 @@ public class LogHelper {
     if (address instanceof InetSocketAddress) {
       InetAddress inetAddress = ((InetSocketAddress) address).getAddress();
       if (inetAddress instanceof Inet4Address) {
-        builder.setType(Address.Type.TYPE_IPV4)
+        builder.setType(Address.Type.IPV4)
             .setAddress(InetAddressUtil.toAddrString(inetAddress));
       } else if (inetAddress instanceof Inet6Address) {
-        builder.setType(Address.Type.TYPE_IPV6)
+        builder.setType(Address.Type.IPV6)
             .setAddress(InetAddressUtil.toAddrString(inetAddress));
       } else {
         logger.log(Level.SEVERE, "unknown type of InetSocketAddress: {}", address);
@@ -417,7 +425,7 @@ public class LogHelper {
     } else if (address.getClass().getName().equals("io.netty.channel.unix.DomainSocketAddress")) {
       // To avoid a compiled time dependency on grpc-netty, we check against the
       // runtime class name.
-      builder.setType(Address.Type.TYPE_UNIX)
+      builder.setType(Address.Type.UNIX)
           .setAddress(address.toString());
     } else {
       builder.setType(Address.Type.TYPE_UNKNOWN).setAddress(address.toString());

gcp-observability/src/main/java/io/grpc/gcp/observability/logging/GcpLogSink.java

@@ -18,29 +18,31 @@ package io.grpc.gcp.observability.logging;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.cloud.MonitoredResource;
+import com.google.api.gax.batching.BatchingSettings;
+import com.google.api.gax.batching.FlowController;
 import com.google.cloud.logging.LogEntry;
 import com.google.cloud.logging.Logging;
 import com.google.cloud.logging.LoggingOptions;
 import com.google.cloud.logging.Payload.JsonPayload;
 import com.google.cloud.logging.Severity;
+import com.google.cloud.logging.v2.stub.LoggingServiceV2StubSettings;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableSet;
 import com.google.protobuf.util.JsonFormat;
 import io.grpc.Internal;
+import io.grpc.gcp.observability.ObservabilityConfig;
 import io.grpc.internal.JsonParser;
 import io.grpc.observabilitylog.v1.GrpcLogRecord;
+import io.opencensus.trace.SpanContext;
 import java.io.IOException;
 import java.time.Instant;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Map;
-import java.util.Objects;
-import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import org.threeten.bp.Duration;
 
 /**
  * Sink for Google Cloud Logging.
@@ -52,22 +54,22 @@ public class GcpLogSink implements Sink {
   private static final String DEFAULT_LOG_NAME =
       "microservices.googleapis.com%2Fobservability%2Fgrpc";
   private static final Severity DEFAULT_LOG_LEVEL = Severity.DEBUG;
-  private static final String K8S_MONITORED_RESOURCE_TYPE = "k8s_container";
-  private static final Set<String> kubernetesResourceLabelSet
-      = ImmutableSet.of("project_id", "location", "cluster_name", "namespace_name",
-      "pod_name", "container_name");
   private final String projectId;
   private final Map<String, String> customTags;
-  private final MonitoredResource kubernetesResource;
   /** Lazily initialize cloud logging client to avoid circular initialization. Because cloud
    * logging APIs also uses gRPC. */
   private volatile Logging gcpLoggingClient;
   private final Collection<String> servicesToExclude;
+  private final boolean isTraceEnabled;
+
+  private final TraceLoggingHelper traceLoggingHelper;
+
 
   @VisibleForTesting
-  GcpLogSink(Logging loggingClient, String projectId, Map<String, String> locationTags,
-      Map<String, String> customTags, Collection<String> servicesToExclude) {
-    this(projectId, locationTags, customTags, servicesToExclude);
+  GcpLogSink(Logging loggingClient, String projectId,
+      ObservabilityConfig config, Collection<String> servicesToExclude,
+      TraceLoggingHelper traceLoggingHelper) {
+    this(projectId, config, servicesToExclude, traceLoggingHelper);
     this.gcpLoggingClient = loggingClient;
   }
 
@@ -77,12 +79,14 @@ public class GcpLogSink implements Sink {
    * @param projectId GCP project id to write logs
    * @param servicesToExclude service names for which log entries should not be generated
    */
-  public GcpLogSink(String projectId, Map<String, String> locationTags,
-      Map<String, String> customTags, Collection<String> servicesToExclude) {
+  public GcpLogSink(String projectId,
+      ObservabilityConfig config, Collection<String> servicesToExclude,
+      TraceLoggingHelper traceLoggingHelper) {
     this.projectId = projectId;
-    this.customTags = getCustomTags(customTags, locationTags, projectId);
-    this.kubernetesResource = getResource(locationTags);
+    this.customTags = getCustomTags(config.getCustomTags());
     this.servicesToExclude = checkNotNull(servicesToExclude, "servicesToExclude");
+    this.isTraceEnabled = config.isEnableCloudTracing();
+    this.traceLoggingHelper = traceLoggingHelper;
   }
 
   /**
@@ -91,7 +95,7 @@ public class GcpLogSink implements Sink {
    * @param logProto gRPC logging proto containing the message to be logged
    */
   @Override
-  public void write(GrpcLogRecord logProto) {
+  public void write(GrpcLogRecord logProto, SpanContext spanContext) {
     if (gcpLoggingClient == null) {
       synchronized (this) {
         if (gcpLoggingClient == null) {
@@ -102,6 +106,7 @@ public class GcpLogSink implements Sink {
     if (servicesToExclude.contains(logProto.getServiceName())) {
       return;
     }
+    LogEntry grpcLogEntry = null;
     try {
       GrpcLogRecord.EventType eventType = logProto.getType();
       // TODO(DNVindhya): make sure all (int, long) values are not displayed as double
@@ -111,59 +116,65 @@ public class GcpLogSink implements Sink {
           LogEntry.newBuilder(JsonPayload.of(logProtoMap))
               .setSeverity(DEFAULT_LOG_LEVEL)
               .setLogName(DEFAULT_LOG_NAME)
-              .setResource(kubernetesResource)
               .setTimestamp(Instant.now());
 
       if (!customTags.isEmpty()) {
         grpcLogEntryBuilder.setLabels(customTags);
       }
-      LogEntry grpcLogEntry = grpcLogEntryBuilder.build();
+
+      addTraceData(grpcLogEntryBuilder, spanContext);
+      grpcLogEntry = grpcLogEntryBuilder.build();
+
       synchronized (this) {
         logger.log(Level.FINEST, "Writing gRPC event : {0} to Cloud Logging", eventType);
         gcpLoggingClient.write(Collections.singleton(grpcLogEntry));
       }
+    } catch (FlowController.FlowControlRuntimeException e) {
+      String grpcLogEntryString = null;
+      if (grpcLogEntry != null) {
+        grpcLogEntryString = grpcLogEntry.toStructuredJsonString();
+      }
+      logger.log(Level.SEVERE, "Limit exceeded while writing log entry to cloud logging");
+      logger.log(Level.SEVERE, "Log entry = ", grpcLogEntryString);
     } catch (Exception e) {
       logger.log(Level.SEVERE, "Caught exception while writing to Cloud Logging", e);
     }
   }
 
+  void addTraceData(LogEntry.Builder builder, SpanContext spanContext) {
+    if (!isTraceEnabled) {
+      return;
+    }
+    traceLoggingHelper.enhanceLogEntry(builder, spanContext);
+  }
+
   Logging createLoggingClient() {
     LoggingOptions.Builder builder = LoggingOptions.newBuilder();
     if (!Strings.isNullOrEmpty(projectId)) {
       builder.setProjectId(projectId);
     }
+    BatchingSettings loggingDefaultBatchingSettings = LoggingServiceV2StubSettings.newBuilder()
+        .writeLogEntriesSettings().getBatchingSettings();
+    // Custom batching settings
+    BatchingSettings grpcLoggingVBatchingSettings = loggingDefaultBatchingSettings.toBuilder()
+        .setDelayThreshold(Duration.ofSeconds(1L)).setFlowControlSettings(
+            loggingDefaultBatchingSettings.getFlowControlSettings().toBuilder()
+                .setMaxOutstandingRequestBytes(52428800L) //50 MiB
+                .setLimitExceededBehavior(FlowController.LimitExceededBehavior.ThrowException)
+                .build()).build();
+    builder.setBatchingSettings(grpcLoggingVBatchingSettings);
     return builder.build().getService();
   }
 
   @VisibleForTesting
-  static Map<String, String> getCustomTags(Map<String, String> customTags,
-      Map<String, String> locationTags, String projectId) {
+  static Map<String, String> getCustomTags(Map<String, String> customTags) {
     ImmutableMap.Builder<String, String> tagsBuilder = ImmutableMap.builder();
-    String sourceProjectId = locationTags.get("project_id");
-    if (!Strings.isNullOrEmpty(projectId)
-        && !Strings.isNullOrEmpty(sourceProjectId)
-        && !Objects.equals(sourceProjectId, projectId)) {
-      tagsBuilder.put("source_project_id", sourceProjectId);
-    }
     if (customTags != null) {
       tagsBuilder.putAll(customTags);
     }
     return tagsBuilder.buildOrThrow();
   }
 
-  @VisibleForTesting
-  static MonitoredResource getResource(Map<String, String> resourceTags) {
-    MonitoredResource.Builder builder = MonitoredResource.newBuilder(K8S_MONITORED_RESOURCE_TYPE);
-    if ((resourceTags != null) && !resourceTags.isEmpty()) {
-      for (Map.Entry<String, String> entry : resourceTags.entrySet()) {
-        String resourceKey = entry.getKey();
-        if (kubernetesResourceLabelSet.contains(resourceKey)) {
-          builder.addLabel(resourceKey, entry.getValue());
-        }
-      }
-    }
-    return builder.build();
-  }
 
   @SuppressWarnings("unchecked")
   private Map<String, Object> protoToMapConverter(GrpcLogRecord logProto)

gcp-observability/src/main/java/io/grpc/gcp/observability/logging/Sink.java

@@ -18,6 +18,7 @@ package io.grpc.gcp.observability.logging;
 
 import io.grpc.Internal;
 import io.grpc.observabilitylog.v1.GrpcLogRecord;
+import io.opencensus.trace.SpanContext;
 
 /**
  * Sink for GCP observability.
@@ -27,7 +28,7 @@ public interface Sink {
   /**
    * Writes the {@code message} to the destination.
    */
-  void write(GrpcLogRecord message);
+  void write(GrpcLogRecord message, SpanContext spanContext);
 
   /**
    * Closes the sink.

gcp-observability/src/main/java/io/grpc/gcp/observability/logging/TraceLoggingHelper.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2023 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.
+ * You may obtain a copy of the License at
+ *
+ *     http://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 io.grpc.gcp.observability.logging;
+
+import com.google.cloud.logging.LogEntry;
+import com.google.common.annotations.VisibleForTesting;
+import io.grpc.Internal;
+import io.opencensus.trace.SpanContext;
+import io.opencensus.trace.TraceId;
+
+@Internal
+public class TraceLoggingHelper {
+
+  private final String tracePrefix;
+
+  public TraceLoggingHelper(String projectId) {
+    this.tracePrefix = "projects/" + projectId + "/traces/";;
+  }
+
+  @VisibleForTesting
+  void enhanceLogEntry(LogEntry.Builder builder, SpanContext spanContext) {
+    addTracingData(tracePrefix, spanContext, builder);
+  }
+
+  private static void addTracingData(
+      String tracePrefix, SpanContext spanContext, LogEntry.Builder builder) {
+    builder.setTrace(formatTraceId(tracePrefix, spanContext.getTraceId()));
+    builder.setSpanId(spanContext.getSpanId().toLowerBase16());
+    builder.setTraceSampled(spanContext.getTraceOptions().isSampled());
+  }
+
+  private static String formatTraceId(String tracePrefix, TraceId traceId) {
+    return tracePrefix + traceId.toLowerBase16();
+  }
+}

gcp-observability/src/main/proto/grpc/observabilitylog/v1/observabilitylog.proto

@@ -20,6 +20,7 @@ package grpc.observabilitylog.v1;
 
 import "google/protobuf/duration.proto";
 import "google/protobuf/timestamp.proto";
+import "google/rpc/code.proto";
 
 option java_multiple_files = true;
 option java_package = "io.grpc.observabilitylog.v1";
@@ -97,7 +98,7 @@ message Payload {
   // the RPC timeout value
   google.protobuf.Duration timeout = 2;
   // The gRPC status code
-  uint32 status_code = 3;
+  google.rpc.Code status_code = 3;
   // The gRPC status message
   string status_message = 4;
   // The value of the grpc-status-details-bin metadata key, if any.
@@ -115,9 +116,9 @@ message Payload {
 message Address {
   enum Type {
     TYPE_UNKNOWN = 0;
-    TYPE_IPV4 = 1;  // in 1.2.3.4 form
-    TYPE_IPV6 = 2;  // IPv6 canonical form (RFC5952 section 4)
-    TYPE_UNIX = 3;  // UDS string
+    IPV4 = 1;  // in 1.2.3.4 form
+    IPV6 = 2;  // IPv6 canonical form (RFC5952 section 4)
+    UNIX = 3;  // UDS string
   }
   Type type = 1;
   string address = 2;

gcp-observability/src/test/java/io/grpc/gcp/observability/GlobalLocationTagsTest.java

@@ -1,110 +0,0 @@
-/*
- * Copyright 2022 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.
- * You may obtain a copy of the License at
- *
- *     http://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 io.grpc.gcp.observability;
-
-import static com.google.common.truth.Truth.assertThat;
-
-import com.google.common.collect.ImmutableMap;
-import com.google.common.io.Files;
-import java.io.File;
-import java.io.IOException;
-import java.nio.charset.StandardCharsets;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
-
-@RunWith(JUnit4.class)
-public class GlobalLocationTagsTest {
-  private static String FILE_CONTENTS =
-      "12:perf_event:/kubepods/burstable/podc43b6442-0725-4fb8-bb1c-d17f5122155c/"
-          + "fe61ca6482b58f4a9831d08d6ea15db25f9fd19b4be19a54df8c6c0eab8742b7\n"
-          + "11:freezer:/kubepods/burstable/podc43b6442-0725-4fb8-bb1c-d17f5122155c/"
-          + "fe61ca6482b58f4a9831d08d6ea15db25f9fd19b4be19a54df8c6c0eab8742b7\n"
-          + "2:rdma:/\n"
-          + "1:name=systemd:/kubepods/burstable/podc43b6442-0725-4fb8-bb1c-d17f5122155c/"
-          + "fe61ca6482b58f4a9831d08d6ea15db25f9fd19b4be19a54df8c6c0eab8742b7\n"
-          + "0::/system.slice/containerd.service\n";
-
-  private static String FILE_CONTENTS_LAST_LINE =
-      "0::/system.slice/containerd.service\n"
-          + "6442-0725-4fb8-bb1c-d17f5122155cslslsl/fe61ca6482b58f4a9831d08d6ea15db25f\n"
-          + "\n"
-          + "12:perf_event:/kubepods/burstable/podc43b6442-0725-4fb8-bb1c-d17f5122155c/e19a54df\n";
-
-  @Rule public TemporaryFolder namespaceFolder = new TemporaryFolder();
-  @Rule public TemporaryFolder hostnameFolder = new TemporaryFolder();
-  @Rule public TemporaryFolder cgroupFolder = new TemporaryFolder();
-
-  @Test
-  public void testContainerIdParsing_lastLine() {
-    String containerId = GlobalLocationTags.getContainerIdFromFileContents(FILE_CONTENTS_LAST_LINE);
-    assertThat(containerId).isEqualTo("e19a54df");
-  }
-
-  @Test
-  public void testContainerIdParsing_fewerFields_notFound() {
-    String containerId = GlobalLocationTags.getContainerIdFromFileContents(
-        "12:/kubepods/burstable/podc43b6442-0725-4fb8-bb1c-d17f5122155c/"
-            + "fe61ca6482b58f4a9831d08d6ea15db25f9fd19b4be19a54df8c6c0eab8742b7\n");
-    assertThat(containerId).isNull();
-  }
-
-  @Test
-  public void testContainerIdParsing_fewerPaths_notFound() {
-    String containerId = GlobalLocationTags.getContainerIdFromFileContents(
-        "12:xdf:/kubepods/podc43b6442-0725-4fb8-bb1c-d17f5122155c/"
-            + "fe61ca6482b58f4a9831d08d6ea15db25f9fd19b4be19a54df8c6c0eab8742b7\n");
-    assertThat(containerId).isNull();
-  }
-
-  @Test
-  public void testPopulateKubernetesValues() throws IOException {
-    File namespaceFile = namespaceFolder.newFile();
-    File hostnameFile = hostnameFolder.newFile();
-    File cgroupFile = cgroupFolder.newFile();
-
-    Files.write("test-namespace1".getBytes(StandardCharsets.UTF_8), namespaceFile);
-    Files.write("test-hostname2\n".getBytes(StandardCharsets.UTF_8), hostnameFile);
-    Files.write(FILE_CONTENTS.getBytes(StandardCharsets.UTF_8), cgroupFile);
-
-    ImmutableMap.Builder<String, String> locationTags = ImmutableMap.builder();
-    GlobalLocationTags.populateFromKubernetesValues(locationTags, namespaceFile.getAbsolutePath(),
-        hostnameFile.getAbsolutePath(), cgroupFile.getAbsolutePath());
-    assertThat(locationTags.buildOrThrow()).containsExactly("container_id",
-        "fe61ca6482b58f4a9831d08d6ea15db25f9fd19b4be19a54df8c6c0eab8742b7", "namespace_name",
-        "test-namespace1", "pod_name", "test-hostname2");
-  }
-
-  @Test
-  public void testNonKubernetesInstanceValues() throws IOException {
-    String namespaceFilePath = "/var/run/secrets/kubernetes.io/serviceaccount/namespace";
-    File hostnameFile = hostnameFolder.newFile();
-    File cgroupFile = cgroupFolder.newFile();
-
-    Files.write("test-hostname2\n".getBytes(StandardCharsets.UTF_8), hostnameFile);
-    Files.write(FILE_CONTENTS.getBytes(StandardCharsets.UTF_8), cgroupFile);
-
-    ImmutableMap.Builder<String, String> locationTags = ImmutableMap.builder();
-    GlobalLocationTags.populateFromKubernetesValues(locationTags,
-        namespaceFilePath, hostnameFile.getAbsolutePath(), cgroupFile.getAbsolutePath());
-    assertThat(locationTags.buildOrThrow()).containsExactly("container_id",
-        "fe61ca6482b58f4a9831d08d6ea15db25f9fd19b4be19a54df8c6c0eab8742b7",
-        "pod_name", "test-hostname2");
-  }
-}

gcp-observability/src/test/java/io/grpc/gcp/observability/LoggingTest.java

@@ -38,9 +38,11 @@ import io.grpc.gcp.observability.interceptors.InternalLoggingServerInterceptor;
 import io.grpc.gcp.observability.interceptors.LogHelper;
 import io.grpc.gcp.observability.logging.GcpLogSink;
 import io.grpc.gcp.observability.logging.Sink;
+import io.grpc.gcp.observability.logging.TraceLoggingHelper;
 import io.grpc.observabilitylog.v1.GrpcLogRecord;
 import io.grpc.testing.GrpcCleanupRule;
 import io.grpc.testing.protobuf.SimpleServiceGrpc;
+import io.opencensus.trace.SpanContext;
 import java.io.IOException;
 import java.util.Collections;
 import java.util.regex.Pattern;
@@ -49,7 +51,9 @@ import org.junit.Ignore;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
+import org.mockito.AdditionalMatchers;
 import org.mockito.ArgumentCaptor;
+import org.mockito.ArgumentMatchers;
 import org.mockito.Mockito;
 
 @RunWith(JUnit4.class)
@@ -59,12 +63,6 @@ public class LoggingTest {
   public static final GrpcCleanupRule cleanupRule = new GrpcCleanupRule();
 
   private static final String PROJECT_ID = "PROJECT";
-  private static final ImmutableMap<String, String> LOCATION_TAGS = ImmutableMap.of(
-      "project_id", "PROJECT",
-      "location", "us-central1-c",
-      "cluster_name", "grpc-observability-cluster",
-      "namespace_name", "default" ,
-      "pod_name", "app1-6c7c58f897-n92c5");
   private static final ImmutableMap<String, String> CUSTOM_TAGS = ImmutableMap.of(
       "KEY1", "Value1",
       "KEY2", "VALUE2");
@@ -111,10 +109,12 @@ public class LoggingTest {
 
     @Override
     public void run() {
+      ObservabilityConfig config = mock(ObservabilityConfig.class);
+      when(config.getCustomTags()).thenReturn(CUSTOM_TAGS);
       Sink sink =
           new GcpLogSink(
-              PROJECT_ID, LOCATION_TAGS, CUSTOM_TAGS, Collections.emptySet());
-      ObservabilityConfig config = mock(ObservabilityConfig.class);
+              PROJECT_ID, config, Collections.emptySet(),
+              mock(TraceLoggingHelper.class));
       LogHelper spyLogHelper = spy(new LogHelper(sink));
       ConfigFilterHelper mockFilterHelper = mock(ConfigFilterHelper.class);
       InternalLoggingChannelInterceptor.Factory channelInterceptorFactory =
@@ -237,7 +237,9 @@ public class LoggingTest {
         // = 8
         assertThat(Mockito.mockingDetails(mockSink).getInvocations().size()).isEqualTo(12);
         ArgumentCaptor<GrpcLogRecord> captor = ArgumentCaptor.forClass(GrpcLogRecord.class);
-        verify(mockSink, times(12)).write(captor.capture());
+        verify(mockSink, times(12)).write(captor.capture(),
+            AdditionalMatchers.or(ArgumentMatchers.isNull(),
+                ArgumentMatchers.any(SpanContext.class)));
         for (GrpcLogRecord record : captor.getAllValues()) {
           assertThat(record.getType()).isInstanceOf(GrpcLogRecord.EventType.class);
           assertThat(record.getLogger()).isInstanceOf(GrpcLogRecord.EventLogger.class);

gcp-observability/src/test/java/io/grpc/gcp/observability/MetadataConfigTest.java

@@ -1,56 +0,0 @@
-/*
- * Copyright 2022 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.
- * You may obtain a copy of the License at
- *
- *     http://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 io.grpc.gcp.observability;
-
-import static com.google.common.truth.Truth.assertThat;
-import static org.mockito.Mockito.when;
-
-import com.google.api.client.testing.http.MockHttpTransport;
-import com.google.api.client.testing.http.MockLowLevelHttpResponse;
-import com.google.auth.http.HttpTransportFactory;
-import java.io.IOException;
-import org.junit.Before;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
-import org.mockito.Mock;
-import org.mockito.MockitoAnnotations;
-
-@RunWith(JUnit4.class)
-public class MetadataConfigTest {
-
-  @Mock HttpTransportFactory httpTransportFactory;
-
-  @Before
-  public void setUp() {
-    MockitoAnnotations.initMocks(this);
-  }
-
-  @Test
-  public void testGetAttribute() throws IOException {
-    MockHttpTransport.Builder builder = new MockHttpTransport.Builder();
-    MockLowLevelHttpResponse response = new MockLowLevelHttpResponse();
-    response.setContent("foo");
-    builder.setLowLevelHttpResponse(response);
-    MockHttpTransport httpTransport = builder.build();
-    when(httpTransportFactory.create()).thenReturn(httpTransport);
-    MetadataConfig metadataConfig = new MetadataConfig(httpTransportFactory);
-    metadataConfig.init();
-    String val = metadataConfig.getAttribute("instance/attributes/cluster-name");
-    assertThat(val).isEqualTo("foo");
-  }
-}

gcp-observability/src/test/java/io/grpc/gcp/observability/interceptors/InternalLoggingChannelInterceptorTest.java

@@ -17,6 +17,7 @@
 package io.grpc.gcp.observability.interceptors;
 
 import static com.google.common.truth.Truth.assertThat;
+import static io.grpc.census.internal.ObservabilityCensusConstants.CLIENT_TRACE_SPAN_CONTEXT_KEY;
 import static io.grpc.gcp.observability.interceptors.LogHelperTest.BYTEARRAY_MARSHALLER;
 import static org.junit.Assert.assertSame;
 import static org.mockito.ArgumentMatchers.any;
@@ -52,6 +53,11 @@ import io.grpc.internal.NoopClientCall;
 import io.grpc.observabilitylog.v1.GrpcLogRecord;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventLogger;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventType;
+import io.opencensus.trace.SpanContext;
+import io.opencensus.trace.SpanId;
+import io.opencensus.trace.TraceId;
+import io.opencensus.trace.TraceOptions;
+import io.opencensus.trace.Tracestate;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
@@ -83,6 +89,14 @@ public class InternalLoggingChannelInterceptorTest {
   public final MockitoRule mockito = MockitoJUnit.rule();
 
   private static final Charset US_ASCII = StandardCharsets.US_ASCII;
+  private static final SpanContext DEFAULT_CLIENT_SPAN_CONTEXT = SpanContext.INVALID;
+  private static final SpanContext SPAN_CONTEXT = SpanContext.create(
+      TraceId.fromLowerBase16("4c6af40c499951eb7de2777ba1e4fefa"),
+      SpanId.fromLowerBase16("de52e84d13dd232d"),
+      TraceOptions.builder().setIsSampled(true).build(),
+      Tracestate.builder().build());
+  private static final CallOptions CALL_OPTIONS_WITH_SPAN_CONTEXT =
+      CallOptions.DEFAULT.withOption(CLIENT_TRACE_SPAN_CONTEXT_KEY, SPAN_CONTEXT);
 
   private InternalLoggingChannelInterceptor.Factory factory;
   private AtomicReference<ClientCall.Listener<byte[]>> interceptedListener;
@@ -192,7 +206,8 @@ public class InternalLoggingChannelInterceptorTest {
           eq(filterParams.headerBytes()),
           eq(EventLogger.CLIENT),
           anyString(),
-          ArgumentMatchers.isNull());
+          ArgumentMatchers.isNull(),
+          eq(DEFAULT_CLIENT_SPAN_CONTEXT));
       verifyNoMoreInteractions(mockLogHelper);
       assertSame(clientInitial, actualClientInitial.get());
     }
@@ -213,7 +228,8 @@ public class InternalLoggingChannelInterceptorTest {
           eq(filterParams.headerBytes()),
           eq(EventLogger.CLIENT),
           anyString(),
-          same(peer));
+          same(peer),
+          any(SpanContext.class));
       verifyNoMoreInteractions(mockLogHelper);
       verify(mockListener).onHeaders(same(serverInitial));
     }
@@ -234,7 +250,8 @@ public class InternalLoggingChannelInterceptorTest {
           same(request),
           eq(filterParams.messageBytes()),
           eq(EventLogger.CLIENT),
-          anyString());
+          anyString(),
+          any(SpanContext.class));
       verifyNoMoreInteractions(mockLogHelper);
       assertSame(request, actualRequest.get());
     }
@@ -251,7 +268,8 @@ public class InternalLoggingChannelInterceptorTest {
           eq("method"),
           eq("the-authority"),
           eq(EventLogger.CLIENT),
-          anyString());
+          anyString(),
+          any(SpanContext.class));
       halfCloseCalled.get(1, TimeUnit.MILLISECONDS);
       verifyNoMoreInteractions(mockLogHelper);
     }
@@ -272,7 +290,8 @@ public class InternalLoggingChannelInterceptorTest {
           same(response),
           eq(filterParams.messageBytes()),
           eq(EventLogger.CLIENT),
-          anyString());
+          anyString(),
+          any(SpanContext.class));
       verifyNoMoreInteractions(mockLogHelper);
       verify(mockListener).onMessage(same(response));
     }
@@ -295,7 +314,8 @@ public class InternalLoggingChannelInterceptorTest {
           eq(filterParams.headerBytes()),
           eq(EventLogger.CLIENT),
           anyString(),
-          same(peer));
+          same(peer),
+          any(SpanContext.class));
       verifyNoMoreInteractions(mockLogHelper);
       verify(mockListener).onClose(same(status), same(trailers));
     }
@@ -312,7 +332,8 @@ public class InternalLoggingChannelInterceptorTest {
           eq("method"),
           eq("the-authority"),
           eq(EventLogger.CLIENT),
-          anyString());
+          anyString(),
+          any(SpanContext.class));
       cancelCalled.get(1, TimeUnit.MILLISECONDS);
     }
   }
@@ -363,7 +384,8 @@ public class InternalLoggingChannelInterceptorTest {
             any(GrpcLogRecord.EventLogger.class),
             anyString(),
             AdditionalMatchers.or(ArgumentMatchers.isNull(),
-                ArgumentMatchers.any()));
+                ArgumentMatchers.any()),
+            any(SpanContext.class));
     Duration timeout = callOptTimeoutCaptor.getValue();
     assertThat(TimeUnit.SECONDS.toNanos(1) - Durations.toNanos(timeout))
         .isAtMost(TimeUnit.MILLISECONDS.toNanos(250));
@@ -422,7 +444,8 @@ public class InternalLoggingChannelInterceptorTest {
             any(GrpcLogRecord.EventLogger.class),
             anyString(),
             AdditionalMatchers.or(ArgumentMatchers.isNull(),
-                ArgumentMatchers.any()));
+                ArgumentMatchers.any()),
+            any(SpanContext.class));
     Duration timeout = contextTimeoutCaptor.getValue();
     assertThat(TimeUnit.SECONDS.toNanos(1) - Durations.toNanos(timeout))
         .isAtMost(TimeUnit.MILLISECONDS.toNanos(250));
@@ -484,7 +507,8 @@ public class InternalLoggingChannelInterceptorTest {
             any(GrpcLogRecord.EventLogger.class),
             anyString(),
             AdditionalMatchers.or(ArgumentMatchers.isNull(),
-                ArgumentMatchers.any()));
+                ArgumentMatchers.any()),
+            any(SpanContext.class));
     Duration timeout = timeoutCaptor.getValue();
     assertThat(LogHelper.min(contextDeadline, callOptionsDeadline))
         .isSameInstanceAs(contextDeadline);
@@ -633,4 +657,172 @@ public class InternalLoggingChannelInterceptorTest {
       assertThat(Mockito.mockingDetails(mockLogHelper).getInvocations().size()).isEqualTo(7);
     }
   }
+
+  @Test
+  public void clientSpanContextLogged_contextSetViaCallOption() {
+    Channel channel = new Channel() {
+      @Override
+      public <RequestT, ResponseT> ClientCall<RequestT, ResponseT> newCall(
+          MethodDescriptor<RequestT, ResponseT> methodDescriptor, CallOptions callOptions) {
+        return new NoopClientCall<RequestT, ResponseT>() {
+          @Override
+          @SuppressWarnings("unchecked")
+          public void start(Listener<ResponseT> responseListener, Metadata headers) {
+            interceptedListener.set((Listener<byte[]>) responseListener);
+            actualClientInitial.set(headers);
+          }
+
+          @Override
+          public void sendMessage(RequestT message) {
+            actualRequest.set(message);
+          }
+
+          @Override
+          public void cancel(String message, Throwable cause) {
+            cancelCalled.set(null);
+          }
+
+          @Override
+          public void halfClose() {
+            halfCloseCalled.set(null);
+          }
+
+          @Override
+          public Attributes getAttributes() {
+            return Attributes.newBuilder().set(Grpc.TRANSPORT_ATTR_REMOTE_ADDR, peer).build();
+          }
+        };
+      }
+
+      @Override
+      public String authority() {
+        return "the-authority";
+      }
+    };
+
+    @SuppressWarnings("unchecked")
+    ClientCall.Listener<byte[]> mockListener = mock(ClientCall.Listener.class);
+
+    MethodDescriptor<byte[], byte[]> method =
+        MethodDescriptor.<byte[], byte[]>newBuilder()
+            .setType(MethodType.UNKNOWN)
+            .setFullMethodName("service/method")
+            .setRequestMarshaller(BYTEARRAY_MARSHALLER)
+            .setResponseMarshaller(BYTEARRAY_MARSHALLER)
+            .build();
+    when(mockFilterHelper.logRpcMethod(method.getFullMethodName(), true))
+        .thenReturn(FilterParams.create(true, 10, 10));
+
+    ClientCall<byte[], byte[]> interceptedLoggingCall =
+        factory.create()
+            .interceptCall(method,
+                CALL_OPTIONS_WITH_SPAN_CONTEXT,
+                channel);
+
+    {
+      interceptedLoggingCall.start(mockListener, new Metadata());
+      ArgumentCaptor<SpanContext> callOptSpanContextCaptor = ArgumentCaptor.forClass(
+          SpanContext.class);
+      verify(mockLogHelper, times(1))
+          .logClientHeader(
+              anyLong(),
+              AdditionalMatchers.or(ArgumentMatchers.isNull(), anyString()),
+              AdditionalMatchers.or(ArgumentMatchers.isNull(), anyString()),
+              AdditionalMatchers.or(ArgumentMatchers.isNull(), anyString()),
+              ArgumentMatchers.isNull(),
+              any(Metadata.class),
+              anyInt(),
+              any(GrpcLogRecord.EventLogger.class),
+              anyString(),
+              AdditionalMatchers.or(ArgumentMatchers.isNull(),
+                  ArgumentMatchers.any()),
+              callOptSpanContextCaptor.capture());
+      SpanContext spanContext = callOptSpanContextCaptor.getValue();
+      assertThat(spanContext).isEqualTo(SPAN_CONTEXT);
+    }
+  }
+
+  @Test
+  public void clientSpanContextLogged_contextNotSetViaCallOption() {
+    Channel channel = new Channel() {
+      @Override
+      public <RequestT, ResponseT> ClientCall<RequestT, ResponseT> newCall(
+          MethodDescriptor<RequestT, ResponseT> methodDescriptor, CallOptions callOptions) {
+        return new NoopClientCall<RequestT, ResponseT>() {
+          @Override
+          @SuppressWarnings("unchecked")
+          public void start(Listener<ResponseT> responseListener, Metadata headers) {
+            interceptedListener.set((Listener<byte[]>) responseListener);
+            actualClientInitial.set(headers);
+          }
+
+          @Override
+          public void sendMessage(RequestT message) {
+            actualRequest.set(message);
+          }
+
+          @Override
+          public void cancel(String message, Throwable cause) {
+            cancelCalled.set(null);
+          }
+
+          @Override
+          public void halfClose() {
+            halfCloseCalled.set(null);
+          }
+
+          @Override
+          public Attributes getAttributes() {
+            return Attributes.newBuilder().set(Grpc.TRANSPORT_ATTR_REMOTE_ADDR, peer).build();
+          }
+        };
+      }
+
+      @Override
+      public String authority() {
+        return "the-authority";
+      }
+    };
+
+    @SuppressWarnings("unchecked")
+    ClientCall.Listener<byte[]> mockListener = mock(ClientCall.Listener.class);
+
+    MethodDescriptor<byte[], byte[]> method =
+        MethodDescriptor.<byte[], byte[]>newBuilder()
+            .setType(MethodType.UNKNOWN)
+            .setFullMethodName("service/method")
+            .setRequestMarshaller(BYTEARRAY_MARSHALLER)
+            .setResponseMarshaller(BYTEARRAY_MARSHALLER)
+            .build();
+    when(mockFilterHelper.logRpcMethod(method.getFullMethodName(), true))
+        .thenReturn(FilterParams.create(true, 10, 10));
+
+    ClientCall<byte[], byte[]> interceptedLoggingCall =
+        factory.create()
+            .interceptCall(method,
+                CallOptions.DEFAULT,
+                channel);
+
+    {
+      interceptedLoggingCall.start(mockListener, new Metadata());
+      ArgumentCaptor<SpanContext> callOptSpanContextCaptor = ArgumentCaptor.forClass(
+          SpanContext.class);
+      verify(mockLogHelper, times(1))
+          .logClientHeader(
+              anyLong(),
+              AdditionalMatchers.or(ArgumentMatchers.isNull(), anyString()),
+              AdditionalMatchers.or(ArgumentMatchers.isNull(), anyString()),
+              AdditionalMatchers.or(ArgumentMatchers.isNull(), anyString()),
+              ArgumentMatchers.isNull(),
+              any(Metadata.class),
+              anyInt(),
+              any(GrpcLogRecord.EventLogger.class),
+              anyString(),
+              AdditionalMatchers.or(ArgumentMatchers.isNull(),
+                  ArgumentMatchers.any()),
+              callOptSpanContextCaptor.capture());
+      SpanContext spanContext = callOptSpanContextCaptor.getValue();
+      assertThat(spanContext).isEqualTo(DEFAULT_CLIENT_SPAN_CONTEXT);
+    }
+  }
 }

gcp-observability/src/test/java/io/grpc/gcp/observability/interceptors/InternalLoggingServerInterceptorTest.java

@@ -45,6 +45,7 @@ import io.grpc.gcp.observability.interceptors.ConfigFilterHelper.FilterParams;
 import io.grpc.internal.NoopServerCall;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventLogger;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventType;
+import io.opencensus.trace.SpanContext;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
@@ -171,7 +172,8 @@ public class InternalLoggingServerInterceptorTest {
           eq(filterParams.headerBytes()),
           eq(EventLogger.SERVER),
           anyString(),
-          same(peer));
+          same(peer),
+          eq(SpanContext.INVALID));
       verifyNoMoreInteractions(mockLogHelper);
     }
 
@@ -191,7 +193,8 @@ public class InternalLoggingServerInterceptorTest {
           eq(filterParams.headerBytes()),
           eq(EventLogger.SERVER),
           anyString(),
-          ArgumentMatchers.isNull());
+          ArgumentMatchers.isNull(),
+          eq(SpanContext.INVALID));
       verifyNoMoreInteractions(mockLogHelper);
       assertSame(serverInitial, actualServerInitial.get());
     }
@@ -212,7 +215,8 @@ public class InternalLoggingServerInterceptorTest {
           same(request),
           eq(filterParams.messageBytes()),
           eq(EventLogger.SERVER),
-          anyString());
+          anyString(),
+          eq(SpanContext.INVALID));
       verifyNoMoreInteractions(mockLogHelper);
       verify(mockListener).onMessage(same(request));
     }
@@ -229,7 +233,8 @@ public class InternalLoggingServerInterceptorTest {
           eq("method"),
           eq("the-authority"),
           eq(EventLogger.SERVER),
-          anyString());
+          anyString(),
+          eq(SpanContext.INVALID));
       verifyNoMoreInteractions(mockLogHelper);
       verify(mockListener).onHalfClose();
     }
@@ -250,7 +255,8 @@ public class InternalLoggingServerInterceptorTest {
           same(response),
           eq(filterParams.messageBytes()),
           eq(EventLogger.SERVER),
-          anyString());
+          anyString(),
+          eq(SpanContext.INVALID));
       verifyNoMoreInteractions(mockLogHelper);
       assertSame(response, actualResponse.get());
     }
@@ -273,7 +279,8 @@ public class InternalLoggingServerInterceptorTest {
           eq(filterParams.headerBytes()),
           eq(EventLogger.SERVER),
           anyString(),
-          ArgumentMatchers.isNull());
+          ArgumentMatchers.isNull(),
+          eq(SpanContext.INVALID));
       verifyNoMoreInteractions(mockLogHelper);
       assertSame(status, actualStatus.get());
       assertSame(trailers, actualTrailers.get());
@@ -291,7 +298,8 @@ public class InternalLoggingServerInterceptorTest {
           eq("method"),
           eq("the-authority"),
           eq(EventLogger.SERVER),
-          anyString());
+          anyString(),
+          eq(SpanContext.INVALID));
       verify(mockListener).onCancel();
     }
   }
@@ -342,7 +350,8 @@ public class InternalLoggingServerInterceptorTest {
         eq(filterParams.headerBytes()),
         eq(EventLogger.SERVER),
         anyString(),
-        ArgumentMatchers.isNull());
+        ArgumentMatchers.isNull(),
+            eq(SpanContext.INVALID));
     verifyNoMoreInteractions(mockLogHelper);
     Duration timeout = timeoutCaptor.getValue();
     assertThat(TimeUnit.SECONDS.toNanos(1) - Durations.toNanos(timeout))

gcp-observability/src/test/java/io/grpc/gcp/observability/interceptors/LogHelperTest.java

@@ -29,6 +29,7 @@ import static org.mockito.Mockito.verify;
 import com.google.protobuf.ByteString;
 import com.google.protobuf.Duration;
 import com.google.protobuf.util.Durations;
+import com.google.rpc.Code;
 import io.grpc.Attributes;
 import io.grpc.Grpc;
 import io.grpc.Metadata;
@@ -42,6 +43,11 @@ import io.grpc.observabilitylog.v1.GrpcLogRecord;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventLogger;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventType;
 import io.grpc.observabilitylog.v1.Payload;
+import io.opencensus.trace.SpanContext;
+import io.opencensus.trace.SpanId;
+import io.opencensus.trace.TraceId;
+import io.opencensus.trace.TraceOptions;
+import io.opencensus.trace.Tracestate;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -74,11 +80,22 @@ public class LogHelperTest {
       Metadata.Key.of("c", Metadata.ASCII_STRING_MARSHALLER);
   private static final int HEADER_LIMIT = 10;
   private static final int MESSAGE_LIMIT = Integer.MAX_VALUE;
+  private static final SpanContext CLIENT_SPAN_CONTEXT = SpanContext.create(
+      TraceId.fromLowerBase16("4c6af40c499951eb7de2777ba1e4fefa"),
+      SpanId.fromLowerBase16("de52e84d13dd232d"),
+      TraceOptions.builder().setIsSampled(true).build(),
+      Tracestate.builder().build());
+  private static final SpanContext SERVER_SPAN_CONTEXT = SpanContext.create(
+      TraceId.fromLowerBase16("549a8a64db2d0c757fdf6bb1bfe84e2c"),
+      SpanId.fromLowerBase16("a5b7704614fe903d"),
+      TraceOptions.builder().setIsSampled(true).build(),
+      Tracestate.builder().build());
 
   private final Metadata nonEmptyMetadata = new Metadata();
   private final Sink sink = mock(GcpLogSink.class);
   private final LogHelper logHelper = new LogHelper(sink);
 
+
   @Before
   public void setUp() {
     nonEmptyMetadata.put(KEY_A, DATA_A);
@@ -94,7 +111,7 @@ public class LogHelperTest {
     assertThat(LogHelper.socketAddressToProto(socketAddress))
         .isEqualTo(Address
             .newBuilder()
-            .setType(Address.Type.TYPE_IPV4)
+            .setType(Address.Type.IPV4)
             .setAddress("127.0.0.1")
             .setIpPort(12345)
             .build());
@@ -109,7 +126,7 @@ public class LogHelperTest {
     assertThat(LogHelper.socketAddressToProto(socketAddress))
         .isEqualTo(Address
             .newBuilder()
-            .setType(Address.Type.TYPE_IPV6)
+            .setType(Address.Type.IPV6)
             .setAddress("2001:db8::2:1") // RFC 5952 section 4: ipv6 canonical form required
             .setIpPort(12345)
             .build());
@@ -287,8 +304,9 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.CLIENT,
           callId,
-          null);
-      verify(sink).write(base);
+          null,
+          CLIENT_SPAN_CONTEXT);
+      verify(sink).write(base, CLIENT_SPAN_CONTEXT);
     }
 
     // logged on server
@@ -303,12 +321,14 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.SERVER,
           callId,
-          peerAddress);
+          peerAddress,
+          SERVER_SPAN_CONTEXT);
       verify(sink).write(
           base.toBuilder()
               .setPeer(LogHelper.socketAddressToProto(peerAddress))
               .setLogger(EventLogger.SERVER)
-              .build());
+              .build(),
+          SERVER_SPAN_CONTEXT);
     }
 
     // timeout is null
@@ -323,11 +343,13 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.CLIENT,
           callId,
-          null);
+          null,
+          CLIENT_SPAN_CONTEXT);
       verify(sink).write(
           base.toBuilder()
               .setPayload(base.getPayload().toBuilder().clearTimeout().build())
-              .build());
+              .build(),
+          CLIENT_SPAN_CONTEXT);
     }
 
     // peerAddress is not null (error on client)
@@ -342,7 +364,8 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.CLIENT,
           callId,
-          peerAddress);
+          peerAddress,
+          CLIENT_SPAN_CONTEXT);
       fail();
     } catch (IllegalArgumentException expected) {
       assertThat(expected).hasMessageThat().contains("peerAddress can only be specified by server");
@@ -385,8 +408,9 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.CLIENT,
           callId,
-          peerAddress);
-      verify(sink).write(base);
+          peerAddress,
+          CLIENT_SPAN_CONTEXT);
+      verify(sink).write(base, CLIENT_SPAN_CONTEXT);
     }
 
     // logged on server
@@ -400,12 +424,14 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.SERVER,
           callId,
-          null);
+          null,
+          SERVER_SPAN_CONTEXT);
       verify(sink).write(
           base.toBuilder()
               .setLogger(EventLogger.SERVER)
               .clearPeer()
-              .build());
+              .build(),
+          SERVER_SPAN_CONTEXT);
     }
 
     // peerAddress is not null (error on server)
@@ -419,7 +445,8 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.SERVER,
           callId,
-          peerAddress);
+          peerAddress,
+          SERVER_SPAN_CONTEXT);
 
       fail();
     } catch (IllegalArgumentException expected) {
@@ -454,7 +481,7 @@ public class LogHelperTest {
     builder.setPeer(LogHelper.socketAddressToProto(peer));
     builder.setPayload(
         builder.getPayload().toBuilder()
-            .setStatusCode(Status.INTERNAL.getCode().value())
+            .setStatusCode(Code.forNumber(Status.INTERNAL.getCode().value()))
             .setStatusMessage("test description")
             .build());
     GrpcLogRecord base = builder.build();
@@ -471,8 +498,9 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.CLIENT,
           callId,
-          peer);
-      verify(sink).write(base);
+          peer,
+          CLIENT_SPAN_CONTEXT);
+      verify(sink).write(base, CLIENT_SPAN_CONTEXT);
     }
 
     // logged on server
@@ -487,12 +515,14 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.SERVER,
           callId,
-          null);
+          null,
+          SERVER_SPAN_CONTEXT);
       verify(sink).write(
           base.toBuilder()
               .clearPeer()
               .setLogger(EventLogger.SERVER)
-              .build());
+              .build(),
+          SERVER_SPAN_CONTEXT);
     }
 
     // peer address is null
@@ -507,11 +537,13 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.CLIENT,
           callId,
-          null);
+          null,
+          CLIENT_SPAN_CONTEXT);
       verify(sink).write(
           base.toBuilder()
               .clearPeer()
-              .build());
+              .build(),
+          CLIENT_SPAN_CONTEXT);
     }
 
     // status description is null
@@ -526,11 +558,13 @@ public class LogHelperTest {
           HEADER_LIMIT,
           EventLogger.CLIENT,
           callId,
-          peer);
+          peer,
+          CLIENT_SPAN_CONTEXT);
       verify(sink).write(
           base.toBuilder()
               .setPayload(base.getPayload().toBuilder().clearStatusMessage().build())
-              .build());
+              .build(),
+          CLIENT_SPAN_CONTEXT);
     }
   }
 
@@ -590,8 +624,9 @@ public class LogHelperTest {
           message,
           MESSAGE_LIMIT,
           EventLogger.CLIENT,
-          callId);
-      verify(sink).write(base);
+          callId,
+          CLIENT_SPAN_CONTEXT);
+      verify(sink).write(base, CLIENT_SPAN_CONTEXT);
     }
     // response message, logged on client
     {
@@ -604,11 +639,13 @@ public class LogHelperTest {
           message,
           MESSAGE_LIMIT,
           EventLogger.CLIENT,
-          callId);
+          callId,
+          CLIENT_SPAN_CONTEXT);
       verify(sink).write(
           base.toBuilder()
               .setType(EventType.SERVER_MESSAGE)
-              .build());
+              .build(),
+          CLIENT_SPAN_CONTEXT);
     }
     // request message, logged on server
     {
@@ -621,11 +658,13 @@ public class LogHelperTest {
           message,
           MESSAGE_LIMIT,
           EventLogger.SERVER,
-          callId);
+          callId,
+          SERVER_SPAN_CONTEXT);
       verify(sink).write(
           base.toBuilder()
               .setLogger(EventLogger.SERVER)
-              .build());
+              .build(),
+          SERVER_SPAN_CONTEXT);
     }
     // response message, logged on server
     {
@@ -638,12 +677,14 @@ public class LogHelperTest {
           message,
           MESSAGE_LIMIT,
           EventLogger.SERVER,
-          callId);
+          callId,
+          SpanContext.INVALID);
       verify(sink).write(
           base.toBuilder()
               .setType(EventType.SERVER_MESSAGE)
               .setLogger(EventLogger.SERVER)
-              .build());
+              .build(),
+          SpanContext.INVALID);
     }
     // message is not of type : com.google.protobuf.Message or byte[]
     {
@@ -656,12 +697,14 @@ public class LogHelperTest {
           "message",
           MESSAGE_LIMIT,
           EventLogger.CLIENT,
-          callId);
+          callId,
+          CLIENT_SPAN_CONTEXT);
       verify(sink).write(
           base.toBuilder()
               .clearPayload()
               .clearPayloadTruncated()
-              .build());
+              .build(),
+          CLIENT_SPAN_CONTEXT);
     }
   }
 

gcp-observability/src/test/java/io/grpc/gcp/observability/logging/GcpLogSinkTest.java

@@ -22,8 +22,8 @@ import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoInteractions;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
 
-import com.google.cloud.MonitoredResource;
 import com.google.cloud.logging.LogEntry;
 import com.google.cloud.logging.Logging;
 import com.google.common.collect.ImmutableMap;
@@ -31,9 +31,15 @@ import com.google.protobuf.Duration;
 import com.google.protobuf.Struct;
 import com.google.protobuf.Value;
 import com.google.protobuf.util.Durations;
+import io.grpc.gcp.observability.ObservabilityConfig;
 import io.grpc.observabilitylog.v1.GrpcLogRecord;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventLogger;
 import io.grpc.observabilitylog.v1.GrpcLogRecord.EventType;
+import io.opencensus.trace.SpanContext;
+import io.opencensus.trace.SpanId;
+import io.opencensus.trace.TraceId;
+import io.opencensus.trace.TraceOptions;
+import io.opencensus.trace.Tracestate;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -57,12 +63,6 @@ public class GcpLogSinkTest {
   @Rule
   public final MockitoRule mockito = MockitoJUnit.rule();
 
-  private static final ImmutableMap<String, String> LOCATION_TAGS =
-      ImmutableMap.of("project_id", "PROJECT",
-      "location", "us-central1-c",
-      "cluster_name", "grpc-observability-cluster",
-      "namespace_name", "default" ,
-      "pod_name", "app1-6c7c58f897-n92c5");
   private static final ImmutableMap<String, String> CUSTOM_TAGS =
       ImmutableMap.of("KEY1", "Value1",
       "KEY2", "VALUE2");
@@ -105,13 +105,16 @@ public class GcpLogSinkTest {
       .build();
   @Mock
   private Logging mockLogging;
+  @Mock
+  private ObservabilityConfig mockConfig;
 
   @Test
   @SuppressWarnings("unchecked")
   public void verifyWrite() throws Exception {
-    GcpLogSink sink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME, LOCATION_TAGS,
-        CUSTOM_TAGS, Collections.emptySet());
-    sink.write(LOG_PROTO);
+    when(mockConfig.getCustomTags()).thenReturn(CUSTOM_TAGS);
+    GcpLogSink sink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME,
+        mockConfig, Collections.emptySet(), new TraceLoggingHelper(DEST_PROJECT_NAME));
+    sink.write(LOG_PROTO, null);
 
     ArgumentCaptor<Collection<LogEntry>> logEntrySetCaptor = ArgumentCaptor.forClass(
         (Class) Collection.class);
@@ -127,10 +130,10 @@ public class GcpLogSinkTest {
   @Test
   @SuppressWarnings("unchecked")
   public void verifyWriteWithTags() {
-    GcpLogSink sink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME, LOCATION_TAGS,
-        CUSTOM_TAGS, Collections.emptySet());
-    MonitoredResource expectedMonitoredResource = GcpLogSink.getResource(LOCATION_TAGS);
-    sink.write(LOG_PROTO);
+    when(mockConfig.getCustomTags()).thenReturn(CUSTOM_TAGS);
+    GcpLogSink sink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME,
+        mockConfig, Collections.emptySet(), new TraceLoggingHelper(DEST_PROJECT_NAME));
+    sink.write(LOG_PROTO, null);
 
     ArgumentCaptor<Collection<LogEntry>> logEntrySetCaptor = ArgumentCaptor.forClass(
         (Class) Collection.class);
@@ -138,7 +141,6 @@ public class GcpLogSinkTest {
     System.out.println(logEntrySetCaptor.getValue());
     for (Iterator<LogEntry> it = logEntrySetCaptor.getValue().iterator(); it.hasNext(); ) {
       LogEntry entry = it.next();
-      assertThat(entry.getResource()).isEqualTo(expectedMonitoredResource);
       assertThat(entry.getLabels()).isEqualTo(CUSTOM_TAGS);
       assertThat(entry.getPayload().getData()).isEqualTo(EXPECTED_STRUCT_LOG_PROTO);
       assertThat(entry.getLogName()).isEqualTo(EXPECTED_LOG_NAME);
@@ -150,10 +152,11 @@ public class GcpLogSinkTest {
   @SuppressWarnings("unchecked")
   public void emptyCustomTags_labelsNotSet() {
     Map<String, String> emptyCustomTags = null;
+    when(mockConfig.getCustomTags()).thenReturn(emptyCustomTags);
     Map<String, String> expectedEmptyLabels = new HashMap<>();
-    GcpLogSink sink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME, LOCATION_TAGS,
-        emptyCustomTags, Collections.emptySet());
-    sink.write(LOG_PROTO);
+    GcpLogSink sink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME,
+        mockConfig, Collections.emptySet(), new TraceLoggingHelper(DEST_PROJECT_NAME));
+    sink.write(LOG_PROTO, null);
 
     ArgumentCaptor<Collection<LogEntry>> logEntrySetCaptor = ArgumentCaptor.forClass(
         (Class) Collection.class);
@@ -169,12 +172,13 @@ public class GcpLogSinkTest {
   @SuppressWarnings("unchecked")
   public void emptyCustomTags_setSourceProject() {
     Map<String, String> emptyCustomTags = null;
+    when(mockConfig.getCustomTags()).thenReturn(emptyCustomTags);
     String projectId = "PROJECT";
-    Map<String, String> expectedLabels = GcpLogSink.getCustomTags(emptyCustomTags, LOCATION_TAGS,
-        projectId);
-    GcpLogSink sink = new GcpLogSink(mockLogging, projectId, LOCATION_TAGS,
-        emptyCustomTags, Collections.emptySet());
-    sink.write(LOG_PROTO);
+    Map<String, String> expectedLabels = GcpLogSink.getCustomTags(emptyCustomTags
+    );
+    GcpLogSink sink = new GcpLogSink(mockLogging, projectId,
+        mockConfig, Collections.emptySet(), new TraceLoggingHelper(DEST_PROJECT_NAME));
+    sink.write(LOG_PROTO, null);
 
     ArgumentCaptor<Collection<LogEntry>> logEntrySetCaptor = ArgumentCaptor.forClass(
         (Class) Collection.class);
@@ -188,9 +192,9 @@ public class GcpLogSinkTest {
 
   @Test
   public void verifyClose() throws Exception {
-    GcpLogSink sink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME, LOCATION_TAGS,
-        CUSTOM_TAGS, Collections.emptySet());
-    sink.write(LOG_PROTO);
+    GcpLogSink sink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME,
+        mockConfig, Collections.emptySet(), new TraceLoggingHelper(DEST_PROJECT_NAME));
+    sink.write(LOG_PROTO, null);
     verify(mockLogging, times(1)).write(anyIterable());
     sink.close();
     verify(mockLogging).close();
@@ -199,9 +203,107 @@ public class GcpLogSinkTest {
 
   @Test
   public void verifyExclude() throws Exception {
-    Sink mockSink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME, LOCATION_TAGS,
-        CUSTOM_TAGS, Collections.singleton("service"));
-    mockSink.write(LOG_PROTO);
+    Sink mockSink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME,
+        mockConfig, Collections.singleton("service"), new TraceLoggingHelper(DEST_PROJECT_NAME));
+    mockSink.write(LOG_PROTO, null);
     verifyNoInteractions(mockLogging);
   }
+
+  @Test
+  @SuppressWarnings("unchecked")
+  public void verifyNoTraceDataInLogs_withTraceDisabled() throws Exception {
+    SpanContext validSpanContext = SpanContext.create(
+        TraceId.fromLowerBase16("4c6af40c499951eb7de2777ba1e4fefa"),
+        SpanId.fromLowerBase16("de52e84d13dd232d"),
+        TraceOptions.builder().setIsSampled(true).build(),
+        Tracestate.builder().build());
+
+    TraceLoggingHelper traceLoggingHelper = new TraceLoggingHelper(DEST_PROJECT_NAME);
+    when(mockConfig.isEnableCloudTracing()).thenReturn(false);
+    Sink mockSink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME,
+        mockConfig, Collections.emptySet(), traceLoggingHelper);
+    mockSink.write(LOG_PROTO, validSpanContext);
+
+    ArgumentCaptor<Collection<LogEntry>> logEntrySetCaptor = ArgumentCaptor.forClass(
+        (Class) Collection.class);
+    verify(mockLogging, times(1)).write(logEntrySetCaptor.capture());
+    for (Iterator<LogEntry> it = logEntrySetCaptor.getValue().iterator(); it.hasNext(); ) {
+      LogEntry entry = it.next();
+      assertThat(entry.getTrace()).isNull(); // Field not present
+      assertThat(entry.getSpanId()).isNull(); // Field not present
+      assertThat(entry.getTraceSampled()).isFalse(); // Default value
+      assertThat(entry.getPayload().getData()).isEqualTo(EXPECTED_STRUCT_LOG_PROTO);
+    }
+  }
+
+  @Test
+  @SuppressWarnings("unchecked")
+  public void verifyTraceDataInLogs_withValidSpanContext() throws Exception {
+    CharSequence traceIdSeq = "4c6af40c499951eb7de2777ba1e4fefa";
+    CharSequence spanIdSeq = "de52e84d13dd232d";
+    TraceId traceId = TraceId.fromLowerBase16(traceIdSeq);
+    SpanId spanId = SpanId.fromLowerBase16(spanIdSeq);
+    boolean traceSampled = true;
+
+    SpanContext validSpanContext = SpanContext.create(traceId, spanId,
+        TraceOptions.builder().setIsSampled(traceSampled).build(),
+        Tracestate.builder().build());
+
+    TraceLoggingHelper traceLoggingHelper = new TraceLoggingHelper(DEST_PROJECT_NAME);
+    when(mockConfig.isEnableCloudTracing()).thenReturn(true);
+    Sink mockSink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME,
+        mockConfig, Collections.emptySet(), traceLoggingHelper);
+    mockSink.write(LOG_PROTO, validSpanContext);
+
+    String expectedTrace = "projects/" + DEST_PROJECT_NAME + "/traces/" + traceIdSeq;
+
+    ArgumentCaptor<Collection<LogEntry>> logEntrySetCaptor = ArgumentCaptor.forClass(
+        (Class) Collection.class);
+    verify(mockLogging, times(1)).write(logEntrySetCaptor.capture());
+    for (Iterator<LogEntry> it = logEntrySetCaptor.getValue().iterator(); it.hasNext(); ) {
+      LogEntry entry = it.next();
+      assertThat(entry.getTrace()).isEqualTo(expectedTrace);
+      assertThat(entry.getSpanId()).isEqualTo("" + spanIdSeq);
+      assertThat(entry.getTraceSampled()).isEqualTo(traceSampled);
+      assertThat(entry.getPayload().getData()).isEqualTo(EXPECTED_STRUCT_LOG_PROTO);
+    }
+
+  }
+
+  @Test
+  @SuppressWarnings("unchecked")
+  public void verifyTraceDataLogs_withNullSpanContext() throws Exception {
+    TraceLoggingHelper traceLoggingHelper = new TraceLoggingHelper(DEST_PROJECT_NAME);
+    when(mockConfig.isEnableCloudTracing()).thenReturn(true);
+    Sink mockSink = new GcpLogSink(mockLogging, DEST_PROJECT_NAME,
+        mockConfig, Collections.emptySet(), traceLoggingHelper);
+
+    String expectedTrace =
+        "projects/" + DEST_PROJECT_NAME + "/traces/00000000000000000000000000000000";
+    String expectedSpanId = "0000000000000000";
+
+    ArgumentCaptor<Collection<LogEntry>> logEntrySetCaptor = ArgumentCaptor.forClass(
+        (Class) Collection.class);
+
+    // Client log with default span context
+    mockSink.write(LOG_PROTO , SpanContext.INVALID);
+    verify(mockLogging, times(1)).write(logEntrySetCaptor.capture());
+    for (Iterator<LogEntry> it = logEntrySetCaptor.getValue().iterator(); it.hasNext(); ) {
+      LogEntry entry = it.next();
+      assertThat(entry.getTrace()).isEqualTo(expectedTrace);
+      assertThat(entry.getSpanId()).isEqualTo(expectedSpanId);
+      assertThat(entry.getTraceSampled()).isFalse();
+    }
+
+    // Server log
+    GrpcLogRecord serverLogProto = LOG_PROTO.toBuilder().setLogger(EventLogger.SERVER).build();
+    mockSink.write(serverLogProto , SpanContext.INVALID);
+    verify(mockLogging, times(2)).write(logEntrySetCaptor.capture());
+    for (Iterator<LogEntry> it = logEntrySetCaptor.getValue().iterator(); it.hasNext(); ) {
+      LogEntry entry = it.next();
+      assertThat(entry.getTrace()).isEqualTo(expectedTrace);
+      assertThat(entry.getSpanId()).isEqualTo(expectedSpanId);
+      assertThat(entry.getTraceSampled()).isFalse();
+    }
+  }
 }

gcp-observability/src/test/java/io/grpc/gcp/observability/logging/TraceLoggingHelperTest.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright 2023 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.
+ * You may obtain a copy of the License at
+ *
+ *     http://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 io.grpc.gcp.observability.logging;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.cloud.logging.LogEntry;
+import io.opencensus.trace.SpanContext;
+import io.opencensus.trace.SpanId;
+import io.opencensus.trace.TraceId;
+import io.opencensus.trace.TraceOptions;
+import io.opencensus.trace.Tracestate;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Tests for {@link TraceLoggingHelper}.
+ */
+@RunWith(JUnit4.class)
+public class TraceLoggingHelperTest {
+
+  private static final String PROJECT = "PROJECT";
+  private static final Tracestate EMPTY_TRACESTATE = Tracestate.builder().build();
+  private static TraceLoggingHelper traceLoggingHelper;
+
+  @Before
+  public void setUp() {
+    traceLoggingHelper = new TraceLoggingHelper(PROJECT);
+  }
+
+  @Test
+  public void enhanceLogEntry_AddSampledSpanContextToLogEntry() {
+    SpanContext spanContext = SpanContext.create(
+        TraceId.fromLowerBase16("5ce724c382c136b2a67bb447e6a6bd27"),
+        SpanId.fromLowerBase16("de52e84d13dd232d"),
+        TraceOptions.builder().setIsSampled(true).build(),
+        EMPTY_TRACESTATE);
+    LogEntry logEntry = getEnhancedLogEntry(traceLoggingHelper, spanContext);
+    assertThat(logEntry.getTraceSampled()).isTrue();
+    assertThat(logEntry.getTrace())
+        .isEqualTo("projects/PROJECT/traces/5ce724c382c136b2a67bb447e6a6bd27");
+    assertThat(logEntry.getSpanId()).isEqualTo("de52e84d13dd232d");
+  }
+
+  @Test
+  public void enhanceLogEntry_AddNonSampledSpanContextToLogEntry() {
+    SpanContext spanContext = SpanContext.create(
+        TraceId.fromLowerBase16("649a8a64db2d0c757fd06bb1bfe84e2c"),
+        SpanId.fromLowerBase16("731e102335b7a5a0"),
+        TraceOptions.builder().setIsSampled(false).build(),
+        EMPTY_TRACESTATE);
+    LogEntry logEntry = getEnhancedLogEntry(traceLoggingHelper, spanContext);
+    assertThat(logEntry.getTraceSampled()).isFalse();
+    assertThat(logEntry.getTrace())
+        .isEqualTo("projects/PROJECT/traces/649a8a64db2d0c757fd06bb1bfe84e2c");
+    assertThat(logEntry.getSpanId()).isEqualTo("731e102335b7a5a0");
+  }
+
+  @Test
+  public void enhanceLogEntry_AddBlankSpanContextToLogEntry() {
+    SpanContext spanContext = SpanContext.INVALID;
+    LogEntry logEntry = getEnhancedLogEntry(traceLoggingHelper, spanContext);
+    assertThat(logEntry.getTraceSampled()).isFalse();
+    assertThat(logEntry.getTrace())
+        .isEqualTo("projects/PROJECT/traces/00000000000000000000000000000000");
+    assertThat(logEntry.getSpanId()).isEqualTo("0000000000000000");
+  }
+
+  private static LogEntry getEnhancedLogEntry(TraceLoggingHelper traceLoggingHelper,
+      SpanContext spanContext) {
+    LogEntry.Builder logEntryBuilder = LogEntry.newBuilder(null);
+    traceLoggingHelper.enhanceLogEntry(logEntryBuilder, spanContext);
+    return logEntryBuilder.build();
+  }
+}

interop-testing/src/main/java/io/grpc/testing/integration/TestServiceClient.java

@@ -71,7 +71,6 @@ public class TestServiceClient {
     } finally {
       client.tearDown();
     }
-    System.exit(0);
   }
 
   private String serverHost = "localhost";

xds/src/main/java/io/grpc/xds/ClusterImplLoadBalancer.java

@@ -35,6 +35,7 @@ import io.grpc.internal.ForwardingClientStreamTracer;
 import io.grpc.internal.ObjectPool;
 import io.grpc.util.ForwardingLoadBalancerHelper;
 import io.grpc.util.ForwardingSubchannel;
+import io.grpc.util.GracefulSwitchLoadBalancer;
 import io.grpc.xds.Bootstrapper.ServerInfo;
 import io.grpc.xds.ClusterImplLoadBalancerProvider.ClusterImplConfig;
 import io.grpc.xds.Endpoints.DropOverload;
@@ -87,7 +88,7 @@ final class ClusterImplLoadBalancer extends LoadBalancer {
   private CallCounterProvider callCounterProvider;
   private ClusterDropStats dropStats;
   private ClusterImplLbHelper childLbHelper;
-  private LoadBalancer childLb;
+  private GracefulSwitchLoadBalancer childSwitchLb;
 
   ClusterImplLoadBalancer(Helper helper) {
     this(helper, ThreadSafeRandomImpl.instance);
@@ -120,7 +121,7 @@ final class ClusterImplLoadBalancer extends LoadBalancer {
       childLbHelper = new ClusterImplLbHelper(
           callCounterProvider.getOrCreate(config.cluster, config.edsServiceName),
           config.lrsServerInfo);
-      childLb = config.childPolicy.getProvider().newLoadBalancer(childLbHelper);
+      childSwitchLb = new GracefulSwitchLoadBalancer(childLbHelper);
       // Assume load report server does not change throughout cluster lifetime.
       if (config.lrsServerInfo != null) {
         dropStats = xdsClient.addClusterDropStats(config.lrsServerInfo, cluster, edsServiceName);
@@ -129,7 +130,9 @@ final class ClusterImplLoadBalancer extends LoadBalancer {
     childLbHelper.updateDropPolicies(config.dropCategories);
     childLbHelper.updateMaxConcurrentRequests(config.maxConcurrentRequests);
     childLbHelper.updateSslContextProviderSupplier(config.tlsContext);
-    childLb.handleResolvedAddresses(
+
+    childSwitchLb.switchTo(config.childPolicy.getProvider());
+    childSwitchLb.handleResolvedAddresses(
         resolvedAddresses.toBuilder()
             .setAttributes(attributes)
             .setLoadBalancingPolicyConfig(config.childPolicy.getConfig())
@@ -139,8 +142,8 @@ final class ClusterImplLoadBalancer extends LoadBalancer {
 
   @Override
   public void handleNameResolutionError(Status error) {
-    if (childLb != null) {
-      childLb.handleNameResolutionError(error);
+    if (childSwitchLb != null) {
+      childSwitchLb.handleNameResolutionError(error);
     } else {
       helper.updateBalancingState(ConnectivityState.TRANSIENT_FAILURE, new ErrorPicker(error));
     }
@@ -151,8 +154,8 @@ final class ClusterImplLoadBalancer extends LoadBalancer {
     if (dropStats != null) {
       dropStats.release();
     }
-    if (childLb != null) {
-      childLb.shutdown();
+    if (childSwitchLb != null) {
+      childSwitchLb.shutdown();
       if (childLbHelper != null) {
         childLbHelper.updateSslContextProviderSupplier(null);
         childLbHelper = null;

xds/src/main/java/io/grpc/xds/RoutingUtils.java

@@ -165,7 +165,8 @@ final class RoutingUtils {
     } else if (pathMatcher.prefix() != null) {
       return pathMatcher.caseSensitive()
           ? fullMethodName.startsWith(pathMatcher.prefix())
-          : fullMethodName.toLowerCase().startsWith(pathMatcher.prefix().toLowerCase());
+          : fullMethodName.toLowerCase(Locale.US).startsWith(
+              pathMatcher.prefix().toLowerCase(Locale.US));
     }
     return pathMatcher.regEx().matches(fullMethodName);
   }

xds/src/main/java/io/grpc/xds/WeightedRoundRobinLoadBalancer.java

@@ -46,6 +46,8 @@ import java.util.PriorityQueue;
 import java.util.Random;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 /**
  * A {@link LoadBalancer} that provides weighted-round-robin load-balancing over
@@ -54,6 +56,8 @@ import java.util.concurrent.TimeUnit;
  */
 @ExperimentalApi("https://github.com/grpc/grpc-java/issues/9885")
 final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
+  private static final Logger log = Logger.getLogger(
+      WeightedRoundRobinLoadBalancer.class.getName());
   private volatile WeightedRoundRobinLoadBalancerConfig config;
   private final SynchronizationContext syncContext;
   private final ScheduledExecutorService timeService;
@@ -76,6 +80,7 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
     this.timeService = checkNotNull(helper.getScheduledExecutorService(), "timeService");
     this.updateWeightTask = new UpdateWeightTask();
     this.random = random;
+    log.log(Level.FINE, "weighted_round_robin LB created");
   }
 
   @VisibleForTesting
@@ -230,7 +235,6 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
   final class WeightedRoundRobinPicker extends ReadyPicker {
     private final List<Subchannel> list;
     private volatile EdfScheduler scheduler;
-    private volatile boolean rrMode;
 
     WeightedRoundRobinPicker(List<Subchannel> list) {
       super(checkNotNull(list, "list"), random.nextInt(list.size()));
@@ -241,16 +245,11 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
 
     @Override
     public PickResult pickSubchannel(PickSubchannelArgs args) {
-      if (rrMode) {
-        return super.pickSubchannel(args);
-      }
-      int pickIndex = scheduler.pick();
-      WrrSubchannel subchannel = (WrrSubchannel) list.get(pickIndex);
+      Subchannel subchannel = list.get(scheduler.pick());
       if (!config.enableOobLoadReport) {
-        return PickResult.withSubchannel(
-           subchannel,
-           OrcaPerRequestUtil.getInstance().newOrcaClientStreamTracerFactory(
-               subchannel.perRpcListener));
+        return PickResult.withSubchannel(subchannel,
+            OrcaPerRequestUtil.getInstance().newOrcaClientStreamTracerFactory(
+                ((WrrSubchannel)subchannel).perRpcListener));
       } else {
         return PickResult.withSubchannel(subchannel);
       }
@@ -266,25 +265,24 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
           weightedChannelCount++;
         }
       }
-      if (weightedChannelCount < 2) {
-        rrMode = true;
-        return;
-      }
       EdfScheduler scheduler = new EdfScheduler(list.size(), random);
-      avgWeight /= 1.0 * weightedChannelCount;
+      if (weightedChannelCount >= 1) {
+        avgWeight /= 1.0 * weightedChannelCount;
+      } else {
+        avgWeight = 1;
+      }
       for (int i = 0; i < list.size(); i++) {
         WrrSubchannel subchannel = (WrrSubchannel) list.get(i);
         double newWeight = subchannel.getWeight();
         scheduler.add(i, newWeight > 0 ? newWeight : avgWeight);
       }
       this.scheduler = scheduler;
-      rrMode = false;
     }
 
     @Override
     public String toString() {
       return MoreObjects.toStringHelper(WeightedRoundRobinPicker.class)
-          .add("list", list).add("rrMode", rrMode).toString();
+          .add("list", list).toString();
     }
 
     @VisibleForTesting

xds/src/test/java/io/grpc/xds/ClusterImplLoadBalancerTest.java

@@ -165,6 +165,41 @@ public class ClusterImplLoadBalancerTest {
         .isSameInstanceAs(xdsClientPool);
   }
 
+  /**
+   * If the control plane switches from using the legacy lb_policy field in the xDS Cluster proto
+   * to the newer load_balancing_policy then the child policy can switch from weighted_target to
+   * xds_wrr_locality (this could happen the opposite way as well). This test assures that this
+   * results in the child LB changing if this were to happen. If this is not done correctly the new
+   * configuration would be given to the old LB implementation which would cause a channel panic.
+   */
+  @Test
+  public void handleResolvedAddresses_childPolicyChanges() {
+    FakeLoadBalancerProvider weightedTargetProvider =
+        new FakeLoadBalancerProvider(XdsLbPolicies.WEIGHTED_TARGET_POLICY_NAME);
+    Object weightedTargetConfig = new Object();
+    ClusterImplConfig configWithWeightedTarget = new ClusterImplConfig(CLUSTER, EDS_SERVICE_NAME,
+        LRS_SERVER_INFO,
+        null, Collections.<DropOverload>emptyList(),
+        new PolicySelection(weightedTargetProvider, weightedTargetConfig), null);
+    EquivalentAddressGroup endpoint = makeAddress("endpoint-addr", locality);
+    deliverAddressesAndConfig(Collections.singletonList(endpoint), configWithWeightedTarget);
+    FakeLoadBalancer childBalancer = Iterables.getOnlyElement(downstreamBalancers);
+    assertThat(childBalancer.name).isEqualTo(XdsLbPolicies.WEIGHTED_TARGET_POLICY_NAME);
+    assertThat(childBalancer.config).isSameInstanceAs(weightedTargetConfig);
+
+    FakeLoadBalancerProvider wrrLocalityProvider =
+        new FakeLoadBalancerProvider(XdsLbPolicies.WRR_LOCALITY_POLICY_NAME);
+    Object wrrLocalityConfig = new Object();
+    ClusterImplConfig configWithWrrLocality = new ClusterImplConfig(CLUSTER, EDS_SERVICE_NAME,
+        LRS_SERVER_INFO,
+        null, Collections.<DropOverload>emptyList(),
+        new PolicySelection(wrrLocalityProvider, wrrLocalityConfig), null);
+    deliverAddressesAndConfig(Collections.singletonList(endpoint), configWithWrrLocality);
+    childBalancer = Iterables.getOnlyElement(downstreamBalancers);
+    assertThat(childBalancer.name).isEqualTo(XdsLbPolicies.WRR_LOCALITY_POLICY_NAME);
+    assertThat(childBalancer.config).isSameInstanceAs(wrrLocalityConfig);
+  }
+
   @Test
   public void nameResolutionError_beforeChildPolicyInstantiated_returnErrorPickerToUpstream() {
     loadBalancer.handleNameResolutionError(Status.UNIMPLEMENTED.withDescription("not found"));

xds/src/test/java/io/grpc/xds/WeightedRoundRobinLoadBalancerTest.java

@@ -29,6 +29,7 @@ import static org.mockito.Mockito.when;
 
 import com.github.xds.data.orca.v3.OrcaLoadReport;
 import com.github.xds.service.orca.v3.OrcaLoadReportRequest;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.protobuf.Duration;
@@ -514,6 +515,62 @@ public class WeightedRoundRobinLoadBalancerTest {
             .isAtMost(0.001);
   }
 
+  @Test
+  public void rrFallback() {
+    syncContext.execute(() -> wrr.acceptResolvedAddresses(ResolvedAddresses.newBuilder()
+        .setAddresses(servers).setLoadBalancingPolicyConfig(weightedConfig)
+        .setAttributes(affinity).build()));
+    verify(helper, times(3)).createSubchannel(
+        any(CreateSubchannelArgs.class));
+    assertThat(fakeClock.getPendingTasks().size()).isEqualTo(1);
+
+    Iterator<Subchannel> it = subchannels.values().iterator();
+    Subchannel readySubchannel1 = it.next();
+    subchannelStateListeners.get(readySubchannel1).onSubchannelState(ConnectivityStateInfo
+        .forNonError(ConnectivityState.READY));
+    Subchannel readySubchannel2  = it.next();
+    subchannelStateListeners.get(readySubchannel2).onSubchannelState(ConnectivityStateInfo
+        .forNonError(ConnectivityState.READY));
+    verify(helper, times(2)).updateBalancingState(
+        eq(ConnectivityState.READY), pickerCaptor.capture());
+    WeightedRoundRobinPicker weightedPicker = pickerCaptor.getAllValues().get(1);
+    assertThat(fakeClock.forwardTime(10, TimeUnit.SECONDS)).isEqualTo(1);
+    WrrSubchannel weightedSubchannel1 = (WrrSubchannel) weightedPicker.getList().get(0);
+    WrrSubchannel weightedSubchannel2 = (WrrSubchannel) weightedPicker.getList().get(1);
+    Map<WrrSubchannel, Integer> qpsByChannel = ImmutableMap.of(weightedSubchannel1, 2,
+        weightedSubchannel2, 1);
+    Map<Subchannel, Integer> pickCount = new HashMap<>();
+    for (int i = 0; i < 1000; i++) {
+      PickResult pickResult = weightedPicker.pickSubchannel(mockArgs);
+      pickCount.put(pickResult.getSubchannel(),
+          pickCount.getOrDefault(pickResult.getSubchannel(), 0) + 1);
+      assertThat(pickResult.getStreamTracerFactory()).isNotNull();
+      WrrSubchannel subchannel = (WrrSubchannel)pickResult.getSubchannel();
+      subchannel.onLoadReport(InternalCallMetricRecorder.createMetricReport(
+          0.1, 0.1, qpsByChannel.get(subchannel), new HashMap<>(), new HashMap<>()));
+    }
+    assertThat(Math.abs(pickCount.get(weightedSubchannel1) / 1000.0 - 1.0 / 2))
+        .isAtMost(0.1);
+    assertThat(Math.abs(pickCount.get(weightedSubchannel2) / 1000.0 - 1.0 / 2))
+        .isAtMost(0.1);
+    pickCount.clear();
+    for (int i = 0; i < 1000; i++) {
+      PickResult pickResult = weightedPicker.pickSubchannel(mockArgs);
+      pickCount.put(pickResult.getSubchannel(),
+          pickCount.getOrDefault(pickResult.getSubchannel(), 0) + 1);
+      assertThat(pickResult.getStreamTracerFactory()).isNotNull();
+      WrrSubchannel subchannel = (WrrSubchannel)pickResult.getSubchannel();
+      subchannel.onLoadReport(InternalCallMetricRecorder.createMetricReport(
+          0.1, 0.1, qpsByChannel.get(subchannel), new HashMap<>(), new HashMap<>()));
+      fakeClock.forwardTime(50, TimeUnit.MILLISECONDS);
+    }
+    assertThat(pickCount.size()).isEqualTo(2);
+    assertThat(Math.abs(pickCount.get(weightedSubchannel1) / 1000.0 - 2.0 / 3))
+        .isAtMost(0.1);
+    assertThat(Math.abs(pickCount.get(weightedSubchannel2) / 1000.0 - 1.0 / 3))
+        .isAtMost(0.1);
+  }
+
   @Test
   public void unknownWeightIsAvgWeight() {
     syncContext.execute(() -> wrr.acceptResolvedAddresses(ResolvedAddresses.newBuilder()
@@ -584,7 +641,6 @@ public class WeightedRoundRobinLoadBalancerTest {
             0.1, 0.1, 1, new HashMap<>(), new HashMap<>()));
     weightedSubchannel2.onLoadReport(InternalCallMetricRecorder.createMetricReport(
             0.2, 0.1, 1, new HashMap<>(), new HashMap<>()));
-    assertThat(weightedPicker.toString()).contains("rrMode=true");
     CyclicBarrier barrier = new CyclicBarrier(2);
     Map<Subchannel, AtomicInteger> pickCount = new ConcurrentHashMap<>();
     pickCount.put(weightedSubchannel1, new AtomicInteger(0));
@@ -638,7 +694,8 @@ public class WeightedRoundRobinLoadBalancerTest {
       pickCount.put(result, pickCount.getOrDefault(result, 0) + 1);
     }
     for (int i = 0; i < capacity; i++) {
-      assertThat(Math.abs(pickCount.get(i) / 1000.0 - weights[i] / totalWeight) ).isAtMost(0.01);
+      assertThat(Math.abs(pickCount.getOrDefault(i, 0) / 1000.0 - weights[i] / totalWeight) )
+          .isAtMost(0.01);
     }
   }
 

xds/src/test/java/io/grpc/xds/orca/OrcaServiceImplTest.java

@@ -19,6 +19,7 @@ package io.grpc.xds.orca;
 import static com.google.common.truth.Truth.assertThat;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.reset;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -115,7 +116,6 @@ public class OrcaServiceImplTest {
   }
 
   @Test
-  @SuppressWarnings("unchecked")
   public void testReportingLifeCycle_serverShutdown() {
     ClientCall<OrcaLoadReportRequest, OrcaLoadReport> call = channel.newCall(
         OpenRcaServiceGrpc.getStreamCoreMetricsMethod(), CallOptions.DEFAULT);
@@ -128,7 +128,7 @@ public class OrcaServiceImplTest {
     OrcaLoadReport expect = OrcaLoadReport.newBuilder().putUtilization("buffer", 0.2).build();
     assertThat(((OrcaServiceImpl)orcaServiceImpl).clientCount.get()).isEqualTo(1);
     verify(listener).onMessage(eq(expect));
-    reset(listener);
+    verify(listener, never()).onClose(any(), any());
     oobServer.shutdownNow();
     assertThat(fakeClock.forwardTime(1, TimeUnit.SECONDS)).isEqualTo(0);
     assertThat(((OrcaServiceImpl)orcaServiceImpl).clientCount.get()).isEqualTo(0);