added BackendMetricPropagationTest and addressed comments

cronet/build.gradle

@@ -57,7 +57,7 @@ dependencies {
 
 task javadocs(type: Javadoc) {
     source = android.sourceSets.main.java.srcDirs
-    classpath += files(android.getBootClasspath())
+    // classpath += files(android.getBootClasspath())
     classpath += files({
         android.libraryVariants.collect { variant ->
             variant.javaCompileProvider.get().classpath

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

@@ -46,6 +46,7 @@ import io.grpc.xds.Endpoints.DropOverload;
 import io.grpc.xds.EnvoyServerProtoData.UpstreamTlsContext;
 import io.grpc.xds.ThreadSafeRandom.ThreadSafeRandomImpl;
 import io.grpc.xds.XdsNameResolverProvider.CallCounterProvider;
+import io.grpc.xds.client.BackendMetricPropagation;
 import io.grpc.xds.client.Bootstrapper.ServerInfo;
 import io.grpc.xds.client.LoadStatsManager2.ClusterDropStats;
 import io.grpc.xds.client.LoadStatsManager2.ClusterLocalityStats;

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

@@ -31,6 +31,7 @@ import io.grpc.NameResolver.ConfigOrError;
 import io.grpc.Status;
 import io.grpc.xds.Endpoints.DropOverload;
 import io.grpc.xds.EnvoyServerProtoData.UpstreamTlsContext;
+import io.grpc.xds.client.BackendMetricPropagation;
 import io.grpc.xds.client.Bootstrapper.ServerInfo;
 import java.util.ArrayList;
 import java.util.Collections;

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

@@ -55,6 +55,7 @@ import io.grpc.xds.EnvoyServerProtoData.UpstreamTlsContext;
 import io.grpc.xds.PriorityLoadBalancerProvider.PriorityLbConfig;
 import io.grpc.xds.PriorityLoadBalancerProvider.PriorityLbConfig.PriorityChildConfig;
 import io.grpc.xds.XdsEndpointResource.EdsUpdate;
+import io.grpc.xds.client.BackendMetricPropagation;
 import io.grpc.xds.client.Bootstrapper.ServerInfo;
 import io.grpc.xds.client.Locality;
 import io.grpc.xds.client.XdsClient;
@@ -191,7 +192,8 @@ final class ClusterResolverLoadBalancer extends LoadBalancer {
         if (instance.type == DiscoveryMechanism.Type.EDS) {
           state = new EdsClusterState(instance.cluster, instance.edsServiceName,
               instance.lrsServerInfo, instance.maxConcurrentRequests, instance.tlsContext,
-              instance.filterMetadata, instance.outlierDetection, instance.backendMetricPropagation);
+              instance.filterMetadata, instance.outlierDetection,
+              instance.backendMetricPropagation);
         } else {  // logical DNS
           state = new LogicalDnsClusterState(instance.cluster, instance.dnsHostName,
               instance.lrsServerInfo, instance.maxConcurrentRequests, instance.tlsContext,
@@ -803,7 +805,8 @@ final class ClusterResolverLoadBalancer extends LoadBalancer {
   private static Map<String, PriorityChildConfig> generateEdsBasedPriorityChildConfigs(
       String cluster, @Nullable String edsServiceName, @Nullable ServerInfo lrsServerInfo,
       @Nullable Long maxConcurrentRequests, @Nullable UpstreamTlsContext tlsContext,
-      Map<String, Struct> filterMetadata, @Nullable BackendMetricPropagation backendMetricPropagation,
+      Map<String, Struct> filterMetadata,
+      @Nullable BackendMetricPropagation backendMetricPropagation,
       @Nullable OutlierDetection outlierDetection, Object endpointLbConfig,
       LoadBalancerRegistry lbRegistry, Map<String,
       Map<Locality, Integer>> prioritizedLocalityWeights, List<DropOverload> dropOverloads) {
@@ -811,7 +814,8 @@ final class ClusterResolverLoadBalancer extends LoadBalancer {
     for (String priority : prioritizedLocalityWeights.keySet()) {
       ClusterImplConfig clusterImplConfig =
           new ClusterImplConfig(cluster, edsServiceName, lrsServerInfo, maxConcurrentRequests,
-              dropOverloads, endpointLbConfig, tlsContext, filterMetadata, backendMetricPropagation);
+              dropOverloads, endpointLbConfig, tlsContext,
+              filterMetadata, backendMetricPropagation);
       LoadBalancerProvider clusterImplLbProvider =
           lbRegistry.getProvider(XdsLbPolicies.CLUSTER_IMPL_POLICY_NAME);
       Object priorityChildPolicy = GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(

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

@@ -29,6 +29,7 @@ import io.grpc.NameResolver.ConfigOrError;
 import io.grpc.Status;
 import io.grpc.xds.EnvoyServerProtoData.OutlierDetection;
 import io.grpc.xds.EnvoyServerProtoData.UpstreamTlsContext;
+import io.grpc.xds.client.BackendMetricPropagation;
 import io.grpc.xds.client.Bootstrapper.ServerInfo;
 import java.util.List;
 import java.util.Map;
@@ -165,9 +166,11 @@ public final class ClusterResolverLoadBalancerProvider extends LoadBalancerProvi
       static DiscoveryMechanism forEds(String cluster, @Nullable String edsServiceName,
           @Nullable ServerInfo lrsServerInfo, @Nullable Long maxConcurrentRequests,
           @Nullable UpstreamTlsContext tlsContext, Map<String, Struct> filterMetadata,
-          OutlierDetection outlierDetection, @Nullable BackendMetricPropagation backendMetricPropagation) {
+          OutlierDetection outlierDetection,
-        return new DiscoveryMechanism(cluster, Type.EDS, edsServiceName, null, lrsServerInfo,
+          @Nullable BackendMetricPropagation backendMetricPropagation) {
-            maxConcurrentRequests, tlsContext, filterMetadata, outlierDetection, backendMetricPropagation);
+        return new DiscoveryMechanism(cluster, Type.EDS, edsServiceName,
+            null, lrsServerInfo, maxConcurrentRequests, tlsContext,
+            filterMetadata, outlierDetection, backendMetricPropagation);
       }
 
       static DiscoveryMechanism forLogicalDns(String cluster, String dnsHostName,
@@ -182,7 +185,8 @@ public final class ClusterResolverLoadBalancerProvider extends LoadBalancerProvi
       @Override
       public int hashCode() {
         return Objects.hash(cluster, type, lrsServerInfo, maxConcurrentRequests, tlsContext,
-            edsServiceName, dnsHostName, filterMetadata, outlierDetection, backendMetricPropagation);
+            edsServiceName, dnsHostName, filterMetadata,
+            outlierDetection, backendMetricPropagation);
       }
 
       @Override

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

@@ -47,10 +47,10 @@ import io.grpc.internal.ServiceConfigUtil.LbConfig;
 import io.grpc.xds.EnvoyServerProtoData.OutlierDetection;
 import io.grpc.xds.EnvoyServerProtoData.UpstreamTlsContext;
 import io.grpc.xds.XdsClusterResource.CdsUpdate;
+import io.grpc.xds.client.BackendMetricPropagation;
 import io.grpc.xds.client.XdsClient.ResourceUpdate;
 import io.grpc.xds.client.XdsResourceType;
 import io.grpc.xds.internal.security.CommonTlsContextUtil;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Locale;
 import java.util.Set;

xds/src/main/java/io/grpc/xds/client/BackendMetricPropagation.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.grpc.xds;
+package io.grpc.xds.client;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
@@ -55,7 +55,8 @@ public final class BackendMetricPropagation {
    * @param metricSpecs list of metric specification strings from CDS resource
    * @return BackendMetricPropagation instance
    */
-  public static BackendMetricPropagation fromMetricSpecs(@Nullable java.util.List<String> metricSpecs) {
+  public static BackendMetricPropagation fromMetricSpecs(
+      @Nullable java.util.List<String> metricSpecs) {
     if (metricSpecs == null || metricSpecs.isEmpty()) {
       return new BackendMetricPropagation(false, false, false, false, ImmutableSet.of());
     }
@@ -89,7 +90,6 @@ public final class BackendMetricPropagation {
               namedMetricKeysBuilder.add(metricKey);
             }
           }
-          break;
       }
     }
 

xds/src/main/java/io/grpc/xds/client/LoadStatsManager2.java

@@ -25,7 +25,6 @@ import com.google.common.base.Supplier;
 import com.google.common.collect.Sets;
 import io.grpc.Internal;
 import io.grpc.Status;
-import io.grpc.xds.BackendMetricPropagation;
 import io.grpc.xds.client.Stats.BackendLoadMetricStats;
 import io.grpc.xds.client.Stats.ClusterStats;
 import io.grpc.xds.client.Stats.DroppedRequests;
@@ -129,8 +128,8 @@ public final class LoadStatsManager2 {
     if (!localityStats.containsKey(locality)) {
       localityStats.put(
           locality,
-          ReferenceCounted.wrap(new ClusterLocalityStats(
+          ReferenceCounted.wrap(new ClusterLocalityStats(cluster, edsServiceName,
-              cluster, edsServiceName, locality, stopwatchSupplier.get(), backendMetricPropagation)));
+              locality, stopwatchSupplier.get(), backendMetricPropagation)));
     }
     ReferenceCounted<ClusterLocalityStats> ref = localityStats.get(locality);
     ref.retain();
@@ -421,7 +420,8 @@ public final class LoadStatsManager2 {
           if (!loadMetricStatsMap.containsKey(metricName)) {
             loadMetricStatsMap.put(metricName, new BackendLoadMetricStats(1, cpuUtilization));
           } else {
-            loadMetricStatsMap.get(metricName).addMetricValueAndIncrementRequestsFinished(cpuUtilization);
+            loadMetricStatsMap.get(metricName)
+                .addMetricValueAndIncrementRequestsFinished(cpuUtilization);
           }
         }
       }
@@ -437,7 +437,8 @@ public final class LoadStatsManager2 {
           if (!loadMetricStatsMap.containsKey(metricName)) {
             loadMetricStatsMap.put(metricName, new BackendLoadMetricStats(1, memUtilization));
           } else {
-            loadMetricStatsMap.get(metricName).addMetricValueAndIncrementRequestsFinished(memUtilization);
+            loadMetricStatsMap.get(metricName)
+                .addMetricValueAndIncrementRequestsFinished(memUtilization);
           }
         }
       }
@@ -451,9 +452,11 @@ public final class LoadStatsManager2 {
         if (shouldPropagate) {
           String metricName = "application_utilization";
           if (!loadMetricStatsMap.containsKey(metricName)) {
-            loadMetricStatsMap.put(metricName, new BackendLoadMetricStats(1, applicationUtilization));
+            loadMetricStatsMap.put(
+                metricName, new BackendLoadMetricStats(1, applicationUtilization));
           } else {
-            loadMetricStatsMap.get(metricName).addMetricValueAndIncrementRequestsFinished(applicationUtilization);
+            loadMetricStatsMap.get(metricName)
+                .addMetricValueAndIncrementRequestsFinished(applicationUtilization);
           }
         }
       }

xds/src/main/java/io/grpc/xds/client/XdsClient.java

@@ -27,7 +27,6 @@ import com.google.common.util.concurrent.MoreExecutors;
 import com.google.protobuf.Any;
 import io.grpc.ExperimentalApi;
 import io.grpc.Status;
-import io.grpc.xds.BackendMetricPropagation;
 import io.grpc.xds.client.Bootstrapper.ServerInfo;
 import java.net.URI;
 import java.net.URISyntaxException;
@@ -385,7 +384,7 @@ public abstract class XdsClient {
   public LoadStatsManager2.ClusterLocalityStats addClusterLocalityStats(
       Bootstrapper.ServerInfo serverInfo, String clusterName, @Nullable String edsServiceName,
       Locality locality) {
-    throw new UnsupportedOperationException();
+    return addClusterLocalityStats(serverInfo, clusterName, edsServiceName, locality, null);
   }
 
   /**

xds/src/main/java/io/grpc/xds/client/XdsClientImpl.java

@@ -37,7 +37,6 @@ import io.grpc.SynchronizationContext;
 import io.grpc.SynchronizationContext.ScheduledHandle;
 import io.grpc.internal.BackoffPolicy;
 import io.grpc.internal.TimeProvider;
-import io.grpc.xds.BackendMetricPropagation;
 import io.grpc.xds.client.Bootstrapper.AuthorityInfo;
 import io.grpc.xds.client.Bootstrapper.ServerInfo;
 import io.grpc.xds.client.XdsClient.ResourceStore;
@@ -409,16 +408,7 @@ public final class XdsClientImpl extends XdsClient implements ResourceStore {
   public LoadStatsManager2.ClusterLocalityStats addClusterLocalityStats(
       final ServerInfo serverInfo, String clusterName, @Nullable String edsServiceName,
       Locality locality) {
-    LoadStatsManager2 loadStatsManager = loadStatsManagerMap.get(serverInfo);
+    return addClusterLocalityStats(serverInfo, clusterName, edsServiceName, locality, null);
-    LoadStatsManager2.ClusterLocalityStats loadCounter =
-        loadStatsManager.getClusterLocalityStats(clusterName, edsServiceName, locality);
-    syncContext.execute(new Runnable() {
-      @Override
-      public void run() {
-        serverLrsClientMap.get(serverInfo).startLoadReporting();
-      }
-    });
-    return loadCounter;
   }
 
   @Override

xds/src/test/java/io/grpc/xds/CdsLoadBalancer2Test.java

@@ -252,7 +252,7 @@ public class CdsLoadBalancer2Test {
             CLUSTER, EDS_SERVICE_NAME, lrsServerInfo, 100L, upstreamTlsContext,
             Collections.emptyMap(), io.grpc.xds.EnvoyServerProtoData.OutlierDetection.create(
                 null, null, null, null, SuccessRateEjection.create(null, null, null, null),
-                FailurePercentageEjection.create(null, null, null, null)))));
+                FailurePercentageEjection.create(null, null, null, null)), null)));
     assertThat(
         GracefulSwitchLoadBalancerAccessor.getChildProvider(childLbConfig.lbConfig).getPolicyName())
         .isEqualTo("wrr_locality_experimental");
@@ -300,7 +300,7 @@ public class CdsLoadBalancer2Test {
         Arrays.asList(
           DiscoveryMechanism.forLogicalDns(
             CLUSTER, "dns.example.com:1111", lrsServerInfo, 100L, upstreamTlsContext,
-            Collections.emptyMap())));
+            Collections.emptyMap(), null)));
     assertThat(
         GracefulSwitchLoadBalancerAccessor.getChildProvider(childLbConfig.lbConfig).getPolicyName())
         .isEqualTo("wrr_locality_experimental");
@@ -335,7 +335,7 @@ public class CdsLoadBalancer2Test {
     assertThat(childLbConfig.discoveryMechanisms).isEqualTo(
         Arrays.asList(
           DiscoveryMechanism.forEds(
-            CLUSTER, EDS_SERVICE_NAME, null, 100L, null, Collections.emptyMap(), null)));
+            CLUSTER, EDS_SERVICE_NAME, null, 100L, null, Collections.emptyMap(), null, null)));
 
     cluster = EDS_CLUSTER.toBuilder()
         .setCircuitBreakers(CircuitBreakers.newBuilder()
@@ -351,7 +351,7 @@ public class CdsLoadBalancer2Test {
     assertThat(childLbConfig.discoveryMechanisms).isEqualTo(
         Arrays.asList(
           DiscoveryMechanism.forEds(
-            CLUSTER, EDS_SERVICE_NAME, null, 200L, null, Collections.emptyMap(), null)));
+            CLUSTER, EDS_SERVICE_NAME, null, 200L, null, Collections.emptyMap(), null, null)));
   }
 
   @Test
@@ -366,7 +366,7 @@ public class CdsLoadBalancer2Test {
     assertThat(childLbConfig.discoveryMechanisms).isEqualTo(
         Arrays.asList(
           DiscoveryMechanism.forEds(
-            CLUSTER, EDS_SERVICE_NAME, null, null, null, Collections.emptyMap(), null)));
+            CLUSTER, EDS_SERVICE_NAME, null, null, null, Collections.emptyMap(), null, null)));
 
     controlPlaneService.setXdsConfig(ADS_TYPE_URL_CDS, ImmutableMap.of());
 
@@ -398,7 +398,7 @@ public class CdsLoadBalancer2Test {
     assertThat(childLbConfig.discoveryMechanisms).isEqualTo(
         Arrays.asList(
           DiscoveryMechanism.forEds(
-            clusterName, EDS_SERVICE_NAME, null, null, null, Collections.emptyMap(), null)));
+            clusterName, EDS_SERVICE_NAME, null, null, null, Collections.emptyMap(), null, null)));
 
     assertThat(this.lastXdsConfig.getClusters()).containsKey(clusterName);
     shutdownLoadBalancer();
@@ -465,11 +465,11 @@ public class CdsLoadBalancer2Test {
     assertThat(childLbConfig.discoveryMechanisms).isEqualTo(
         Arrays.asList(
           DiscoveryMechanism.forEds(
-            cluster3, EDS_SERVICE_NAME, null, 100L, null, Collections.emptyMap(), null),
+            cluster3, EDS_SERVICE_NAME, null, 100L, null, Collections.emptyMap(), null, null),
           DiscoveryMechanism.forEds(
-            cluster4, EDS_SERVICE_NAME, null, null, null, Collections.emptyMap(), null),
+            cluster4, EDS_SERVICE_NAME, null, null, null, Collections.emptyMap(), null, null),
           DiscoveryMechanism.forLogicalDns(
-            cluster2, "dns.example.com:1111", null, null, null, Collections.emptyMap())));
+            cluster2, "dns.example.com:1111", null, null, null, Collections.emptyMap(), null)));
     assertThat(
         GracefulSwitchLoadBalancerAccessor.getChildProvider(childLbConfig.lbConfig).getPolicyName())
         .isEqualTo("ring_hash_experimental");  // dominated by top-level cluster's config

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

@@ -68,6 +68,7 @@ import io.grpc.xds.EnvoyServerProtoData.UpstreamTlsContext;
 import io.grpc.xds.WeightedTargetLoadBalancerProvider.WeightedPolicySelection;
 import io.grpc.xds.WeightedTargetLoadBalancerProvider.WeightedTargetConfig;
 import io.grpc.xds.XdsNameResolverProvider.CallCounterProvider;
+import io.grpc.xds.client.BackendMetricPropagation;
 import io.grpc.xds.client.Bootstrapper.ServerInfo;
 import io.grpc.xds.client.LoadReportClient;
 import io.grpc.xds.client.LoadStatsManager2;
@@ -260,7 +261,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     EquivalentAddressGroup endpoint = makeAddress("endpoint-addr", locality);
     deliverAddressesAndConfig(Collections.singletonList(endpoint), config);
     FakeLoadBalancer childBalancer = Iterables.getOnlyElement(downstreamBalancers);
@@ -281,7 +282,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     EquivalentAddressGroup endpoint = makeAddress("endpoint-addr", locality);
     deliverAddressesAndConfig(Collections.singletonList(endpoint), config);
     FakeLoadBalancer leafBalancer = Iterables.getOnlyElement(downstreamBalancers);
@@ -312,7 +313,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     EquivalentAddressGroup endpoint = makeAddress("endpoint-addr", locality);
     deliverAddressesAndConfig(Collections.singletonList(endpoint), config);
     FakeLoadBalancer leafBalancer = Iterables.getOnlyElement(downstreamBalancers);
@@ -336,7 +337,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     EquivalentAddressGroup endpoint = makeAddress("endpoint-addr", locality);
     deliverAddressesAndConfig(Collections.singletonList(endpoint), config);
     FakeLoadBalancer leafBalancer = Iterables.getOnlyElement(downstreamBalancers);
@@ -431,7 +432,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(pickFirstProvider,
             pickFirstConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     EquivalentAddressGroup endpoint1 = makeAddress("endpoint-addr1", locality1);
     EquivalentAddressGroup endpoint2 = makeAddress("endpoint-addr2", locality2);
     deliverAddressesAndConfig(Arrays.asList(endpoint1, endpoint2), config);
@@ -521,7 +522,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.singletonList(DropOverload.create("throttle", 500_000)),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     EquivalentAddressGroup endpoint = makeAddress("endpoint-addr", locality);
     deliverAddressesAndConfig(Collections.singletonList(endpoint), config);
     when(mockRandom.nextInt(anyInt())).thenReturn(499_999, 999_999, 1_000_000);
@@ -555,7 +556,7 @@ public class ClusterImplLoadBalancerTest {
         Collections.singletonList(DropOverload.create("lb", 1_000_000)),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     loadBalancer.acceptResolvedAddresses(
         ResolvedAddresses.newBuilder()
             .setAddresses(Collections.singletonList(endpoint))
@@ -604,7 +605,7 @@ public class ClusterImplLoadBalancerTest {
         maxConcurrentRequests, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     EquivalentAddressGroup endpoint = makeAddress("endpoint-addr", locality);
     deliverAddressesAndConfig(Collections.singletonList(endpoint), config);
     assertThat(downstreamBalancers).hasSize(1);  // one leaf balancer
@@ -651,7 +652,7 @@ public class ClusterImplLoadBalancerTest {
         maxConcurrentRequests, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     deliverAddressesAndConfig(Collections.singletonList(endpoint), config);
 
     result = currentPicker.pickSubchannel(pickSubchannelArgs);
@@ -699,7 +700,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     EquivalentAddressGroup endpoint = makeAddress("endpoint-addr", locality);
     deliverAddressesAndConfig(Collections.singletonList(endpoint), config);
     assertThat(downstreamBalancers).hasSize(1);  // one leaf balancer
@@ -750,7 +751,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     // One locality with two endpoints.
     EquivalentAddressGroup endpoint1 = makeAddress("endpoint-addr1", locality);
     EquivalentAddressGroup endpoint2 = makeAddress("endpoint-addr2", locality);
@@ -790,7 +791,7 @@ public class ClusterImplLoadBalancerTest {
           null, Collections.<DropOverload>emptyList(),
           GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
               weightedTargetProvider, weightedTargetConfig),
-          null, Collections.emptyMap());
+          null, Collections.emptyMap(), null);
       EquivalentAddressGroup endpoint1 = makeAddress("endpoint-addr1", locality,
           "authority-host-name");
       deliverAddressesAndConfig(Arrays.asList(endpoint1), config);
@@ -841,7 +842,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     EquivalentAddressGroup endpoint1 = makeAddress("endpoint-addr1", locality,
         "authority-host-name");
     deliverAddressesAndConfig(Arrays.asList(endpoint1), config);
@@ -889,7 +890,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        upstreamTlsContext, Collections.emptyMap());
+        upstreamTlsContext, Collections.emptyMap(), null);
     // One locality with two endpoints.
     EquivalentAddressGroup endpoint1 = makeAddress("endpoint-addr1", locality);
     EquivalentAddressGroup endpoint2 = makeAddress("endpoint-addr2", locality);
@@ -914,7 +915,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        null, Collections.emptyMap());
+        null, Collections.emptyMap(), null);
     deliverAddressesAndConfig(Arrays.asList(endpoint1, endpoint2), config);
     assertThat(Iterables.getOnlyElement(downstreamBalancers)).isSameInstanceAs(leafBalancer);
     subchannel = leafBalancer.helper.createSubchannel(args);  // creates new connections
@@ -931,7 +932,7 @@ public class ClusterImplLoadBalancerTest {
         null, Collections.<DropOverload>emptyList(),
         GracefulSwitchLoadBalancer.createLoadBalancingPolicyConfig(
             weightedTargetProvider, weightedTargetConfig),
-        upstreamTlsContext, Collections.emptyMap());
+        upstreamTlsContext, Collections.emptyMap(), null);
     deliverAddressesAndConfig(Arrays.asList(endpoint1, endpoint2), config);
     assertThat(Iterables.getOnlyElement(downstreamBalancers)).isSameInstanceAs(leafBalancer);
     subchannel = leafBalancer.helper.createSubchannel(args);  // creates new connections
@@ -1241,8 +1242,9 @@ public class ClusterImplLoadBalancerTest {
     @Override
     public ClusterLocalityStats addClusterLocalityStats(
         ServerInfo lrsServerInfo, String clusterName, @Nullable String edsServiceName,
-        Locality locality) {
+        Locality locality, BackendMetricPropagation backendMetricPropagation) {
-      return loadStatsManager.getClusterLocalityStats(clusterName, edsServiceName, locality);
+      return loadStatsManager.getClusterLocalityStats(
+          clusterName, edsServiceName, locality, backendMetricPropagation);
     }
 
     @Override

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

@@ -139,16 +139,16 @@ public class ClusterResolverLoadBalancerTest {
       FailurePercentageEjection.create(100, 100, 100, 100));
   private final DiscoveryMechanism edsDiscoveryMechanism1 =
       DiscoveryMechanism.forEds(CLUSTER1, EDS_SERVICE_NAME1, LRS_SERVER_INFO, 100L, tlsContext,
-          Collections.emptyMap(), null);
+          Collections.emptyMap(), null, null);
   private final DiscoveryMechanism edsDiscoveryMechanism2 =
       DiscoveryMechanism.forEds(CLUSTER2, EDS_SERVICE_NAME2, LRS_SERVER_INFO, 200L, tlsContext,
-          Collections.emptyMap(), null);
+          Collections.emptyMap(), null, null);
   private final DiscoveryMechanism edsDiscoveryMechanismWithOutlierDetection =
       DiscoveryMechanism.forEds(CLUSTER1, EDS_SERVICE_NAME1, LRS_SERVER_INFO, 100L, tlsContext,
-          Collections.emptyMap(), outlierDetection);
+          Collections.emptyMap(), outlierDetection, null);
   private final DiscoveryMechanism logicalDnsDiscoveryMechanism =
       DiscoveryMechanism.forLogicalDns(CLUSTER_DNS, DNS_HOST_NAME, LRS_SERVER_INFO, 300L, null,
-          Collections.emptyMap());
+          Collections.emptyMap(), null);
 
   private final SynchronizationContext syncContext = new SynchronizationContext(
       new Thread.UncaughtExceptionHandler() {

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

@@ -491,7 +491,7 @@ public class GcpAuthenticationFilterTest {
     parsedMetadata.put("FILTER_INSTANCE_NAME", new AudienceWrapper("TEST_AUDIENCE"));
     try {
       CdsUpdate.Builder cdsUpdate = CdsUpdate.forEds(
-              CLUSTER_NAME, EDS_NAME, null, null, null, null, false)
+              CLUSTER_NAME, EDS_NAME, null, null, null, null, false, null)
           .lbPolicyConfig(getWrrLbConfigAsMap());
       return cdsUpdate.parsedMetadata(parsedMetadata.build()).build();
     } catch (IOException ex) {
@@ -504,7 +504,7 @@ public class GcpAuthenticationFilterTest {
     parsedMetadata.put("FILTER_INSTANCE_NAME", new AudienceWrapper("NEW_TEST_AUDIENCE"));
     try {
       CdsUpdate.Builder cdsUpdate = CdsUpdate.forEds(
-              CLUSTER_NAME, EDS_NAME, null, null, null, null, false)
+              CLUSTER_NAME, EDS_NAME, null, null, null, null, false, null)
           .lbPolicyConfig(getWrrLbConfigAsMap());
       return cdsUpdate.parsedMetadata(parsedMetadata.build()).build();
     } catch (IOException ex) {
@@ -516,7 +516,7 @@ public class GcpAuthenticationFilterTest {
     ImmutableMap.Builder<String, Object> parsedMetadata = ImmutableMap.builder();
     parsedMetadata.put("FILTER_INSTANCE_NAME", "TEST_AUDIENCE");
     CdsUpdate.Builder cdsUpdate = CdsUpdate.forEds(
-            CLUSTER_NAME, EDS_NAME, null, null, null, null, false)
+            CLUSTER_NAME, EDS_NAME, null, null, null, null, false, null)
         .lbPolicyConfig(getWrrLbConfigAsMap());
     return cdsUpdate.parsedMetadata(parsedMetadata.build()).build();
   }

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

@@ -154,7 +154,6 @@ public class XdsClientFederationTest {
     }
   }
 
-
   /**
    * Assures that when an {@link XdsClient} is asked to add cluster locality stats it appropriately
    * starts {@link LoadReportClient}s to do that.

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

@@ -1235,7 +1235,7 @@ public class XdsNameResolverTest {
       FakeXdsClient xdsClient, String... clusterNames) {
     for (String clusterName : clusterNames) {
       CdsUpdate.Builder forEds = CdsUpdate
-          .forEds(clusterName, clusterName, null, null, null, null, false)
+          .forEds(clusterName, clusterName, null, null, null, null, false, null)
               .roundRobinLbPolicy();
       xdsClient.deliverCdsUpdate(clusterName, forEds.build());
       EdsUpdate edsUpdate = new EdsUpdate(clusterName,

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

@@ -272,7 +272,7 @@ public class XdsTestUtils {
     XdsEndpointResource.EdsUpdate edsUpdate = new XdsEndpointResource.EdsUpdate(
         EDS_NAME, lbEndpointsMap, Collections.emptyList());
     XdsClusterResource.CdsUpdate cdsUpdate = XdsClusterResource.CdsUpdate.forEds(
-        CLUSTER_NAME, EDS_NAME, serverInfo, null, null, null, false)
+        CLUSTER_NAME, EDS_NAME, serverInfo, null, null, null, false, null)
         .lbPolicyConfig(getWrrLbConfigAsMap()).build();
     XdsConfig.XdsClusterConfig clusterConfig = new XdsConfig.XdsClusterConfig(
         CLUSTER_NAME, cdsUpdate, new EndpointConfig(StatusOr.fromValue(edsUpdate)));

xds/src/test/java/io/grpc/xds/client/BackendMetricPropagationTest.java

@@ -0,0 +1,142 @@
+/*
+ * Copyright 2025 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.xds.client;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.util.Arrays.asList;
+
+import com.google.common.collect.ImmutableList;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Unit tests for {@link BackendMetricPropagation}.
+ */
+@RunWith(JUnit4.class)
+public class BackendMetricPropagationTest {
+
+  @Test
+  public void fromMetricSpecs_nullInput() {
+    BackendMetricPropagation config = BackendMetricPropagation.fromMetricSpecs(null);
+    assertThat(config.propagateCpuUtilization).isFalse();
+    assertThat(config.propagateMemUtilization).isFalse();
+    assertThat(config.propagateApplicationUtilization).isFalse();
+    assertThat(config.shouldPropagateNamedMetric("any")).isFalse();
+  }
+
+  @Test
+  public void fromMetricSpecs_emptyInput() {
+    BackendMetricPropagation config = BackendMetricPropagation.fromMetricSpecs(ImmutableList.of());
+    assertThat(config.propagateCpuUtilization).isFalse();
+    assertThat(config.propagateMemUtilization).isFalse();
+    assertThat(config.propagateApplicationUtilization).isFalse();
+    assertThat(config.shouldPropagateNamedMetric("any")).isFalse();
+  }
+
+  @Test
+  public void fromMetricSpecs_partialStandardMetrics() {
+    BackendMetricPropagation config = BackendMetricPropagation.fromMetricSpecs(
+        ImmutableList.of("cpu_utilization", "mem_utilization"));
+    assertThat(config.propagateCpuUtilization).isTrue();
+    assertThat(config.propagateMemUtilization).isTrue();
+    assertThat(config.propagateApplicationUtilization).isFalse();
+    assertThat(config.shouldPropagateNamedMetric("any")).isFalse();
+  }
+
+  @Test
+  public void fromMetricSpecs_allStandardMetrics() {
+    BackendMetricPropagation config = BackendMetricPropagation.fromMetricSpecs(
+        ImmutableList.of("cpu_utilization", "mem_utilization", "application_utilization"));
+    assertThat(config.propagateCpuUtilization).isTrue();
+    assertThat(config.propagateMemUtilization).isTrue();
+    assertThat(config.propagateApplicationUtilization).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("any")).isFalse();
+  }
+
+  @Test
+  public void fromMetricSpecs_wildcardNamedMetrics() {
+    BackendMetricPropagation config = BackendMetricPropagation.fromMetricSpecs(
+        ImmutableList.of("named_metrics.*"));
+    assertThat(config.propagateCpuUtilization).isFalse();
+    assertThat(config.propagateMemUtilization).isFalse();
+    assertThat(config.propagateApplicationUtilization).isFalse();
+    assertThat(config.shouldPropagateNamedMetric("any_key")).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("another_key")).isTrue();
+  }
+
+  @Test
+  public void fromMetricSpecs_specificNamedMetrics() {
+    BackendMetricPropagation config = BackendMetricPropagation.fromMetricSpecs(
+        ImmutableList.of("named_metrics.foo", "named_metrics.bar"));
+    assertThat(config.shouldPropagateNamedMetric("foo")).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("bar")).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("baz")).isFalse();
+    assertThat(config.shouldPropagateNamedMetric("any")).isFalse();
+  }
+
+  @Test
+  public void fromMetricSpecs_mixedStandardAndNamed() {
+    BackendMetricPropagation config = BackendMetricPropagation.fromMetricSpecs(
+        ImmutableList.of("cpu_utilization", "named_metrics.foo", "named_metrics.bar"));
+    assertThat(config.propagateCpuUtilization).isTrue();
+    assertThat(config.propagateMemUtilization).isFalse();
+    assertThat(config.shouldPropagateNamedMetric("foo")).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("bar")).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("baz")).isFalse();
+  }
+
+  @Test
+  public void fromMetricSpecs_wildcardAndSpecificNamedMetrics() {
+    BackendMetricPropagation config = BackendMetricPropagation.fromMetricSpecs(
+        ImmutableList.of("named_metrics.foo", "named_metrics.*"));
+    assertThat(config.shouldPropagateNamedMetric("foo")).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("bar")).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("any_other_key")).isTrue();
+  }
+
+  @Test
+  public void fromMetricSpecs_malformedAndUnknownSpecs_areIgnored() {
+    BackendMetricPropagation config = BackendMetricPropagation.fromMetricSpecs(
+        asList(
+            "cpu_utilization",      // valid
+            null,                   // ignored
+            "disk_utilization",     // ignored
+            "named_metrics.",       // ignored, empty key
+            "named_metrics.valid"   // valid
+        ));
+
+    assertThat(config.propagateCpuUtilization).isTrue();
+    assertThat(config.propagateMemUtilization).isFalse();
+    assertThat(config.shouldPropagateNamedMetric("disk_utilization")).isFalse();
+    assertThat(config.shouldPropagateNamedMetric("valid")).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("")).isFalse(); // from the empty key
+  }
+
+  @Test
+  public void fromMetricSpecs_duplicateSpecs_areHandledGracefully() {
+    BackendMetricPropagation config = BackendMetricPropagation.fromMetricSpecs(
+        ImmutableList.of(
+            "cpu_utilization",
+            "named_metrics.foo",
+            "cpu_utilization",
+            "named_metrics.foo"));
+    assertThat(config.propagateCpuUtilization).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("foo")).isTrue();
+    assertThat(config.shouldPropagateNamedMetric("bar")).isFalse();
+  }
+}