xdsClient metrics structure

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

@@ -288,6 +288,7 @@ public static final class Args {
     @Nullable private final ChannelLogger channelLogger;
     @Nullable private final Executor executor;
     @Nullable private final String overrideAuthority;
+    @Nullable private final MetricRecorder metricRecorder;
 
     private Args(
         Integer defaultPort,
@@ -297,7 +298,8 @@ private Args(
         @Nullable ScheduledExecutorService scheduledExecutorService,
         @Nullable ChannelLogger channelLogger,
         @Nullable Executor executor,
-        @Nullable String overrideAuthority) {
+        @Nullable String overrideAuthority,
+        @Nullable MetricRecorder metricRecorder) {
       this.defaultPort = checkNotNull(defaultPort, "defaultPort not set");
       this.proxyDetector = checkNotNull(proxyDetector, "proxyDetector not set");
       this.syncContext = checkNotNull(syncContext, "syncContext not set");
@@ -306,6 +308,7 @@ private Args(
       this.channelLogger = channelLogger;
       this.executor = executor;
       this.overrideAuthority = overrideAuthority;
+      this.metricRecorder = metricRecorder;
     }
 
     /**
@@ -403,6 +406,17 @@ public String getOverrideAuthority() {
       return overrideAuthority;
     }
 
+    /**
+     * Returns the {@link MetricRecorder} that the channel uses to record metrics.
+     *
+     * @since 1.67.0
+     */
+    @Nullable
+    @ExperimentalApi("Insert GitHub issue")
+    public MetricRecorder getMetricRecorder() {
+      return metricRecorder;
+    }
+
 
     @Override
     public String toString() {
@@ -415,6 +429,7 @@ public String toString() {
           .add("channelLogger", channelLogger)
           .add("executor", executor)
           .add("overrideAuthority", overrideAuthority)
+          .add("metricRecorder", metricRecorder)
           .toString();
     }
 
@@ -433,6 +448,7 @@ public Builder toBuilder() {
       builder.setChannelLogger(channelLogger);
       builder.setOffloadExecutor(executor);
       builder.setOverrideAuthority(overrideAuthority);
+      builder.setMetricRecorder(metricRecorder);
       return builder;
     }
 
@@ -459,6 +475,7 @@ public static final class Builder {
       private ChannelLogger channelLogger;
       private Executor executor;
       private String overrideAuthority;
+      private MetricRecorder metricRecorder;
 
       Builder() {
       }
@@ -545,6 +562,17 @@ public Builder setOverrideAuthority(String authority) {
         return this;
       }
 
+      /**
+       * See {@link Args#getMetricRecorder()}. This is an optional field.
+       *
+       * @since 1.67.0
+       */
+      @ExperimentalApi("Insert github issue")
+      public Builder setMetricRecorder(MetricRecorder metricRecorder) {
+        this.metricRecorder = metricRecorder;
+        return this;
+      }
+
       /**
        * Builds an {@link Args}.
        *
@@ -554,7 +582,8 @@ public Args build() {
         return
             new Args(
                 defaultPort, proxyDetector, syncContext, serviceConfigParser,
-                scheduledExecutorService, channelLogger, executor, overrideAuthority);
+                scheduledExecutorService, channelLogger, executor, overrideAuthority,
+                metricRecorder);
       }
     }
   }

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

@@ -589,6 +589,8 @@ ClientStream newSubstream(
             builder.maxHedgedAttempts,
             loadBalancerFactory);
     this.authorityOverride = builder.authorityOverride;
+    this.metricRecorder = new MetricRecorderImpl(builder.metricSinks,
+        MetricInstrumentRegistry.getDefaultRegistry());
     this.nameResolverArgs =
         NameResolver.Args.newBuilder()
             .setDefaultPort(builder.getDefaultPort())
@@ -599,6 +601,7 @@ ClientStream newSubstream(
             .setChannelLogger(channelLogger)
             .setOffloadExecutor(this.offloadExecutorHolder)
             .setOverrideAuthority(this.authorityOverride)
+            .setMetricRecorder(this.metricRecorder)
             .build();
     this.nameResolver = getNameResolver(
         targetUri, authorityOverride, nameResolverProvider, nameResolverArgs);
@@ -671,8 +674,6 @@ public CallTracer create() {
       }
       serviceConfigUpdated = true;
     }
-    this.metricRecorder = new MetricRecorderImpl(builder.metricSinks,
-        MetricInstrumentRegistry.getDefaultRegistry());
   }
 
   @VisibleForTesting

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

@@ -17,6 +17,7 @@
 package io.grpc.xds;
 
 import io.grpc.Internal;
+import io.grpc.MetricRecorder;
 import io.grpc.internal.ObjectPool;
 import io.grpc.xds.client.XdsClient;
 import io.grpc.xds.client.XdsInitializationException;
@@ -36,6 +37,11 @@ public static void setDefaultProviderBootstrapOverride(Map<String, ?> bootstrap)
 
   public static ObjectPool<XdsClient> getOrCreate(String target)
       throws XdsInitializationException {
-    return SharedXdsClientPoolProvider.getDefaultProvider().getOrCreate(target);
+    return getOrCreate(target, new MetricRecorder() {});
+  }
+
+  public static ObjectPool<XdsClient> getOrCreate(String target, MetricRecorder metricRecorder)
+      throws XdsInitializationException {
+    return SharedXdsClientPoolProvider.getDefaultProvider().getOrCreate(target, metricRecorder);
   }
 }

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

@@ -21,6 +21,7 @@
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableList;
+import io.grpc.MetricRecorder;
 import io.grpc.internal.ExponentialBackoffPolicy;
 import io.grpc.internal.GrpcUtil;
 import io.grpc.internal.ObjectPool;
@@ -56,6 +57,7 @@ final class SharedXdsClientPoolProvider implements XdsClientPoolFactory {
   private final Object lock = new Object();
   private final AtomicReference<Map<String, ?>> bootstrapOverride = new AtomicReference<>();
   private final Map<String, ObjectPool<XdsClient>> targetToXdsClientMap = new ConcurrentHashMap<>();
+  private final Map<String, MetricRecorder> targetToMetricRecorderMap = new ConcurrentHashMap<>();
 
   SharedXdsClientPoolProvider() {
     this(new GrpcBootstrapperImpl());
@@ -82,7 +84,14 @@ public ObjectPool<XdsClient> get(String target) {
   }
 
   @Override
+  @Nullable
   public ObjectPool<XdsClient> getOrCreate(String target) throws XdsInitializationException {
+    return this.getOrCreate(target, new MetricRecorder() {});
+  }
+
+  @Override
+  public ObjectPool<XdsClient> getOrCreate(String target, MetricRecorder metricRecorder)
+      throws XdsInitializationException {
     ObjectPool<XdsClient> ref = targetToXdsClientMap.get(target);
     if (ref == null) {
       synchronized (lock) {
@@ -98,8 +107,12 @@ public ObjectPool<XdsClient> getOrCreate(String target) throws XdsInitialization
           if (bootstrapInfo.servers().isEmpty()) {
             throw new XdsInitializationException("No xDS server provided");
           }
-          ref = new RefCountedXdsClientObjectPool(bootstrapInfo, target);
+          MetricRecorder metricRecorderForTarget = targetToMetricRecorderMap.get(target);
+          metricRecorder =
+              metricRecorderForTarget != null ? metricRecorderForTarget : metricRecorder;
+          ref = new RefCountedXdsClientObjectPool(bootstrapInfo, target, metricRecorder);
           targetToXdsClientMap.put(target, ref);
+          targetToMetricRecorderMap.putIfAbsent(target, metricRecorder);
         }
       }
     }
@@ -124,6 +137,7 @@ static class RefCountedXdsClientObjectPool implements ObjectPool<XdsClient> {
         new ExponentialBackoffPolicy.Provider();
     private final BootstrapInfo bootstrapInfo;
     private final String target; // The target associated with the xDS client.
+    private final MetricRecorder metricRecorder;
     private final Object lock = new Object();
     @GuardedBy("lock")
     private ScheduledExecutorService scheduler;
@@ -133,9 +147,11 @@ static class RefCountedXdsClientObjectPool implements ObjectPool<XdsClient> {
     private int refCount;
 
     @VisibleForTesting
-    RefCountedXdsClientObjectPool(BootstrapInfo bootstrapInfo, String target) {
+    RefCountedXdsClientObjectPool(BootstrapInfo bootstrapInfo, String target,
+        MetricRecorder metricRecorder) {
       this.bootstrapInfo = checkNotNull(bootstrapInfo);
       this.target = target;
+      this.metricRecorder = metricRecorder;
     }
 
     @Override
@@ -154,7 +170,9 @@ public XdsClient getObject() {
               GrpcUtil.STOPWATCH_SUPPLIER,
               TimeProvider.SYSTEM_TIME_PROVIDER,
               MessagePrinter.INSTANCE,
-              new TlsContextManagerImpl(bootstrapInfo));
+              new TlsContextManagerImpl(bootstrapInfo),
+              getTarget(),
+              new XdsClientMetricReporterImpl(metricRecorder));
         }
         refCount++;
         return xdsClient;

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

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2024 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;
+
+import io.grpc.Internal;
+import io.grpc.xds.client.XdsClient;
+
+/**
+ * Interface for reporting metrics from the xDS client.
+ * We need this indirection, to de couple Xds from OpenTelemetry
+ */
+@Internal
+public interface XdsClientMetricReporter {
+
+  /**
+   * Reports resource update counts.
+   *
+   * @param validResourceCount the number of resources that were successfully updated.
+   * @param invalidResourceCount the number of resources that failed to update.
+   * @param target the xDS management server name for the load balancing policy this update is for.
+   * @param xdsServer the xDS management server address for this update.
+   * @param resourceType the type of resource (e.g., "LDS", "RDS", "CDS", "EDS").
+   */
+  default void reportResourceUpdates(long validResourceCount, long invalidResourceCount,
+      String target, String xdsServer, String resourceType) {
+  }
+
+  /**
+   * Reports xDS server failure counts.
+   *
+   * @param serverFailure the number of times the xDS server has failed.
+   * @param target the xDS management server name for the load balancing policy this failure is for.
+   * @param xdsServer the xDS management server address for this failure.
+   */
+  default void reportServerFailure(long serverFailure, String target, String xdsServer) {
+  }
+
+  /**
+   * Sets the {@link XdsClient} instance to the reporter.
+   *
+   * @param xdsClient the {@link XdsClient} instance.
+   */
+  default void setXdsClient(XdsClient xdsClient) {
+  }
+
+  /**
+   * Closes the metric reporter.
+   */
+  default void close() {
+  }
+
+  /**
+   * Interface for reporting metrics from the xDS client callbacks.
+   *
+   */
+  interface CallbackMetricReporter {
+
+    /**
+     * Reports resource counts in the cache.
+     *
+     * @param resourceCount the number of resources in the cache.
+     * @param cacheState the state of the cache (e.g., "SYNCED", "DOES_NOT_EXIST").
+     * @param resourceType the type of resource (e.g., "LDS", "RDS", "CDS", "EDS").
+     * @param target the xDS management server name for the load balancing policy this count is
+     *     for.
+     */
+    // TODO(@dnvindhya): include the "authority" label once authority is available.
+    default void reportResourceCounts(long resourceCount, String cacheState, String resourceType,
+        String target) {
+    }
+
+    /**
+     * Reports server connection status.
+     *
+     * @param isConnected {@code true} if the client is connected to the xDS server, {@code false}
+     *        otherwise.
+     * @param target the xDS management server name for the load balancing policy this connection
+     *        is for.
+     * @param xdsServer the xDS management server address for this connection.
+     * @since 0.1.0
+     */
+    default void reportServerConnections(int isConnected, String target, String xdsServer) {
+    }
+  }
+}