examples: add examples-orca (grpc#9204)

Author: YifeiZhuang

RELEASING.md

@@ -36,6 +36,7 @@ $ VERSION_FILES=(
   examples/example-tls/build.gradle
   examples/example-tls/pom.xml
   examples/example-xds/build.gradle
+  examples/example-orca/build.gradle
   )
 ```
 

examples/example-orca/README.md

@@ -0,0 +1,44 @@
+gRPC ORCA Example
+================
+
+The ORCA example consists of a Hello World client and a Hello World server. Out-of-the-box the 
+client behaves the same the hello-world version and the server behaves similar to the
+example-hostname. In addition, they have been integrated with backend metrics reporting features.
+
+### Build the example
+
+Build the ORCA hello-world example client & server. From the `grpc-java/examples/examples-orca`
+directory:
+```
+$ ../gradlew installDist
+```
+
+This creates the scripts `build/install/example-orca/bin/custom-backend-metrics-client` and
+`build/install/example-orca/bin/custom-backend-metrics-server`.
+
+### Run the example
+
+To use ORCA, you have to instrument both the client and the server.
+At the client, in your own load balancer policy, you use gRPC APIs to install listeners to receive
+per-query and out-of-band metric reports.
+At the server, you add a server interceptor provided by gRPC in order to send per-query backend metrics.
+And you register a bindable service, also provided by gRPC, in order to send out-of-band backend metrics.
+Meanwhile, you update the metrics data from your own measurements.
+
+That's it! In this example, we simply put all the necessary pieces together to demonstrate the
+metrics reporting mechanism.
+
+1. To start the ORCA enabled example server on its default port of 50051, run:
+```
+$ ./build/install/example-orca/bin/custom-backend-metrics-server
+```
+
+2. In a different terminal window, run the ORCA enabled example client:
+```
+$ ./build/install/example-orca/bin/custom-backend-metrics-client "orca tester" 1500
+```
+The first command line argument (`orca tester`) is the name you wish to include in
+the greeting request to the server and the second argument
+(`1500`) is the time period (in milliseconds) you want to run the client before it shut downed so that it will show 
+more periodic backend metrics reports. You are expected to see the metrics data printed out. Try it!
+

examples/example-orca/build.gradle

@@ -0,0 +1,62 @@
+plugins {
+    id 'application' // Provide convenience executables for trying out the examples.
+    // 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
+
+def grpcVersion = '1.48.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def protocVersion = '3.19.2'
+
+dependencies {
+    implementation "io.grpc:grpc-protobuf:${grpcVersion}"
+    implementation "io.grpc:grpc-services:${grpcVersion}"
+    implementation "io.grpc:grpc-stub:${grpcVersion}"
+    implementation "io.grpc:grpc-xds:${grpcVersion}"
+    compileOnly "org.apache.tomcat:annotations-api:6.0.53"
+
+}
+
+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 CustomBackendMetricsClient(type: CreateStartScripts) {
+    mainClass = 'io.grpc.examples.orca.CustomBackendMetricsClient'
+    applicationName = 'custom-backend-metrics-client'
+    outputDir = new File(project.buildDir, 'tmp/scripts/' + name)
+    classpath = startScripts.classpath
+}
+
+task CustomBackendMetricsServer(type: CreateStartScripts) {
+    mainClass = 'io.grpc.examples.orca.CustomBackendMetricsServer'
+    applicationName = 'custom-backend-metrics-server'
+    outputDir = new File(project.buildDir, 'tmp/scripts/' + name)
+    classpath = startScripts.classpath
+}
+
+applicationDistribution.into('bin') {
+    from(CustomBackendMetricsClient)
+    from(CustomBackendMetricsServer)
+    fileMode = 0755
+}

examples/example-orca/settings.gradle

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

examples/example-orca/src/main/java/io/grpc/examples/orca/CustomBackendMetricsClient.java

@@ -0,0 +1,106 @@
+/*
+ * 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.examples.orca;
+
+import static io.grpc.examples.orca.CustomBackendMetricsLoadBalancerProvider.EXAMPLE_LOAD_BALANCER;
+
+import io.grpc.Channel;
+import io.grpc.LoadBalancerRegistry;
+import io.grpc.ManagedChannel;
+import io.grpc.ManagedChannelBuilder;
+import io.grpc.StatusRuntimeException;
+import io.grpc.examples.helloworld.GreeterGrpc;
+import io.grpc.examples.helloworld.HelloReply;
+import io.grpc.examples.helloworld.HelloRequest;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * A simple xDS client that requests a greeting from {@link CustomBackendMetricsServer}.
+ * The client channel is configured to use an example load balancer policy
+ * {@link CustomBackendMetricsLoadBalancerProvider} which integrates with ORCA metrics reporting.
+ */
+public class CustomBackendMetricsClient {
+  private static final Logger logger = Logger.getLogger(CustomBackendMetricsClient.class.getName());
+
+  private final GreeterGrpc.GreeterBlockingStub blockingStub;
+
+  /** Construct client for accessing HelloWorld server using the existing channel. */
+  public CustomBackendMetricsClient(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 = "orca tester";
+    // The example defaults to the same behavior as the hello world example.
+    // To receive more periodic OOB metrics reports, use duration argument to a longer value.
+    String target = "localhost:50051";
+    long timeBeforeShutdown = 1500;
+    if (args.length > 0) {
+      if ("--help".equals(args[0])) {
+        System.err.println("Usage: [name [duration [target]]]");
+        System.err.println("");
+        System.err.println("  name    The name you wish to be greeted by. Defaults to " + user);
+        System.err.println("  duration  The time period in milliseconds that the client application " +
+            "wait until shutdown. Defaults to " + timeBeforeShutdown);
+        System.err.println("  target  The server to connect to. Defaults to " + target);
+        System.exit(1);
+      }
+      user = args[0];
+    }
+    if (args.length > 1) {
+      timeBeforeShutdown = Long.parseLong(args[1]);
+    }
+
+    if (args.length > 2) {
+      target = args[2];
+    }
+
+    LoadBalancerRegistry.getDefaultRegistry().register(
+        new CustomBackendMetricsLoadBalancerProvider());
+    ManagedChannel channel = ManagedChannelBuilder.forTarget(target)
+        .defaultLoadBalancingPolicy(EXAMPLE_LOAD_BALANCER)
+        .usePlaintext()
+        .build();
+    try {
+      CustomBackendMetricsClient client = new CustomBackendMetricsClient(channel);
+      client.greet(user);
+      Thread.sleep(timeBeforeShutdown);
+    } finally {
+      channel.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
+    }
+  }
+}

examples/example-orca/src/main/java/io/grpc/examples/orca/CustomBackendMetricsLoadBalancerProvider.java

@@ -0,0 +1,140 @@
+/*
+ * 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.examples.orca;
+
+import io.grpc.ConnectivityState;
+import io.grpc.LoadBalancer;
+import io.grpc.LoadBalancerProvider;
+import io.grpc.LoadBalancerRegistry;
+import io.grpc.util.ForwardingLoadBalancer;
+import io.grpc.util.ForwardingLoadBalancerHelper;
+import io.grpc.xds.orca.OrcaOobUtil;
+import io.grpc.xds.orca.OrcaPerRequestUtil;
+import io.grpc.xds.shaded.com.github.xds.data.orca.v3.OrcaLoadReport;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Implements a test LB policy that receives ORCA load reports.
+ * The load balancer mostly delegates to {@link io.grpc.internal.PickFirstLoadBalancerProvider},
+ * in addition, it installs {@link OrcaOobUtil.OrcaOobReportListener} and
+ * {@link OrcaPerRequestUtil.OrcaPerRequestReportListener} to be notified with backend metrics.
+ */
+final class CustomBackendMetricsLoadBalancerProvider extends LoadBalancerProvider {
+
+  static final String EXAMPLE_LOAD_BALANCER = "example_backend_metrics_load_balancer";
+
+  @Override
+  public LoadBalancer newLoadBalancer(LoadBalancer.Helper helper) {
+    return new CustomBackendMetricsLoadBalancer(helper);
+  }
+
+  @Override
+  public boolean isAvailable() {
+    return true;
+  }
+
+  @Override
+  public int getPriority() {
+    return 5;
+  }
+
+  @Override
+  public String getPolicyName() {
+    return EXAMPLE_LOAD_BALANCER;
+  }
+
+  private final class CustomBackendMetricsLoadBalancer extends ForwardingLoadBalancer {
+    private LoadBalancer delegate;
+
+    public CustomBackendMetricsLoadBalancer(LoadBalancer.Helper helper) {
+      this.delegate = LoadBalancerRegistry.getDefaultRegistry()
+          .getProvider("pick_first")
+          .newLoadBalancer(new CustomBackendMetricsLoadBalancerHelper(helper));
+    }
+
+    @Override
+    public LoadBalancer delegate() {
+      return delegate;
+    }
+
+    private final class CustomBackendMetricsLoadBalancerHelper
+        extends ForwardingLoadBalancerHelper {
+      private final LoadBalancer.Helper orcaHelper;
+
+      public CustomBackendMetricsLoadBalancerHelper(LoadBalancer.Helper helper) {
+        this.orcaHelper = OrcaOobUtil.newOrcaReportingHelper(helper);
+      }
+
+      @Override
+      public LoadBalancer.Subchannel createSubchannel(LoadBalancer.CreateSubchannelArgs args) {
+        LoadBalancer.Subchannel subchannel = super.createSubchannel(args);
+        // Installs ORCA OOB metrics reporting listener and configures to receive report every 1s.
+        // The interval can not be smaller than server minimum report interval configuration,
+        // otherwise it is treated as server minimum report interval.
+        OrcaOobUtil.setListener(subchannel, new OrcaOobUtil.OrcaOobReportListener() {
+              @Override
+              public void onLoadReport(OrcaLoadReport orcaLoadReport) {
+                System.out.println("Example load balancer received OOB metrics report:\n"
+                    + orcaLoadReport);
+              }
+            },
+            OrcaOobUtil.OrcaReportingConfig.newBuilder()
+                .setReportInterval(1, TimeUnit.SECONDS)
+                .build()
+        );
+        return subchannel;
+      }
+
+      @Override
+      public void updateBalancingState(ConnectivityState newState, LoadBalancer.SubchannelPicker newPicker) {
+        delegate().updateBalancingState(newState, new MayReportLoadPicker(newPicker));
+      }
+
+      @Override
+      public LoadBalancer.Helper delegate() {
+        return orcaHelper;
+      }
+    }
+
+    private final class MayReportLoadPicker extends LoadBalancer.SubchannelPicker {
+      private LoadBalancer.SubchannelPicker delegate;
+
+      public MayReportLoadPicker(LoadBalancer.SubchannelPicker delegate) {
+        this.delegate = delegate;
+      }
+
+      @Override
+      public LoadBalancer.PickResult pickSubchannel(LoadBalancer.PickSubchannelArgs args) {
+        LoadBalancer.PickResult result = delegate.pickSubchannel(args);
+        if (result.getSubchannel() == null) {
+          return result;
+        }
+        // Installs ORCA per-query metrics reporting listener.
+        return LoadBalancer.PickResult.withSubchannel(
+            result.getSubchannel(),
+            OrcaPerRequestUtil.getInstance().newOrcaClientStreamTracerFactory(
+                new OrcaPerRequestUtil.OrcaPerRequestReportListener() {
+                  @Override
+                  public void onLoadReport(OrcaLoadReport orcaLoadReport) {
+                    System.out.println("Example load balancer received per-rpc metrics report:\n"
+                        + orcaLoadReport);
+                  }
+                }));
+      }
+    }
+  }
+}