1 /* 2 * Copyright 2022 The gRPC Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package io.grpc.examples.loadbalance; 18 19 import io.grpc.Server; 20 import io.grpc.ServerBuilder; 21 import io.grpc.examples.helloworld.GreeterGrpc; 22 import io.grpc.examples.helloworld.HelloReply; 23 import io.grpc.examples.helloworld.HelloRequest; 24 import io.grpc.stub.StreamObserver; 25 26 import java.io.IOException; 27 import java.util.concurrent.TimeUnit; 28 import java.util.logging.Logger; 29 30 public class LoadBalanceServer { 31 private static final Logger logger = Logger.getLogger(LoadBalanceServer.class.getName()); 32 static public final int serverCount = 3; 33 static public final int startPort = 50051; 34 private Server[] servers; 35 start()36 private void start() throws IOException { 37 servers = new Server[serverCount]; 38 for (int i = 0; i < serverCount; i++) { 39 int port = startPort + i; 40 servers[i] = ServerBuilder.forPort(port) 41 .addService(new GreeterImpl(port)) 42 .build() 43 .start(); 44 logger.info("Server started, listening on " + port); 45 } 46 Runtime.getRuntime().addShutdownHook(new Thread(() -> { 47 System.err.println("*** shutting down gRPC server since JVM is shutting down"); 48 try { 49 LoadBalanceServer.this.stop(); 50 } catch (InterruptedException e) { 51 e.printStackTrace(System.err); 52 } 53 System.err.println("*** server shut down"); 54 })); 55 } 56 stop()57 private void stop() throws InterruptedException { 58 for (int i = 0; i < serverCount; i++) { 59 if (servers[i] != null) { 60 servers[i].shutdown().awaitTermination(30, TimeUnit.SECONDS); 61 } 62 } 63 } 64 blockUntilShutdown()65 private void blockUntilShutdown() throws InterruptedException { 66 for (int i = 0; i < serverCount; i++) { 67 if (servers[i] != null) { 68 servers[i].awaitTermination(); 69 } 70 } 71 } 72 main(String[] args)73 public static void main(String[] args) throws IOException, InterruptedException { 74 final LoadBalanceServer server = new LoadBalanceServer(); 75 server.start(); 76 server.blockUntilShutdown(); 77 } 78 79 static class GreeterImpl extends GreeterGrpc.GreeterImplBase { 80 81 int port; 82 GreeterImpl(int port)83 public GreeterImpl(int port) { 84 this.port = port; 85 } 86 87 @Override sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver)88 public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) { 89 HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName() + " from server<" + this.port + ">").build(); 90 responseObserver.onNext(reply); 91 responseObserver.onCompleted(); 92 } 93 } 94 } 95