code: /*
   * Copyright 2014 Google Inc. All rights reserved.
   *
   * 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.
   */
  
  import MyGame.Example.Monster;
  import MyGame.Example.MonsterStorageGrpc;
  import MyGame.Example.Stat;
  import com.google.flatbuffers.FlatBufferBuilder;
  import io.grpc.ManagedChannel;
  import io.grpc.ManagedChannelBuilder;
  import io.grpc.Server;
  import io.grpc.ServerBuilder;
  import io.grpc.stub.StreamObserver;
  import org.junit.Assert;
  
  import java.io.IOException;
  import java.lang.InterruptedException;
  import java.nio.ByteBuffer;
  import java.util.Iterator;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicReference;
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.concurrent.CountDownLatch;
  
  
  /**
   * Demonstrates basic client-server interaction using grpc-java over netty.
   */
  public class JavaGrpcTest {
      static final String BIG_MONSTER_NAME = "Cyberdemon";
      static final short nestedMonsterHp = 600;
      static final short nestedMonsterMana = 1024;
      static final int numStreamedMsgs = 10;
      static final int timeoutMs = 3000;
      static Server server;
      static ManagedChannel channel;
      static MonsterStorageGrpc.MonsterStorageBlockingStub blockingStub;
      static MonsterStorageGrpc.MonsterStorageStub asyncStub;
  
      static class MyService extends MonsterStorageGrpc.MonsterStorageImplBase {
          @Override
          public void store(Monster request, io.grpc.stub.StreamObserver<Stat> responseObserver) {
              Assert.assertEquals(request.name(), BIG_MONSTER_NAME);
              Assert.assertEquals(request.hp(), nestedMonsterHp);
              Assert.assertEquals(request.mana(), nestedMonsterMana);
              System.out.println("Received store request from " + request.name());
              // Create a response from the incoming request name.
              Stat stat = GameFactory.createStat("Hello " + request.name(), 100, 10);
              responseObserver.onNext(stat);
              responseObserver.onCompleted();
          }
  
          @Override
          public void retrieve(Stat request, io.grpc.stub.StreamObserver<Monster> responseObserver) {
              // Create 10 monsters for streaming response.
              for (int i=0; i<numStreamedMsgs; i++) {
                  Monster monster = GameFactory.createMonsterFromStat(request, i);
                  responseObserver.onNext(monster);
              }
              responseObserver.onCompleted();
          }
  
          @Override
          public StreamObserver<Monster> getMaxHitPoint(final StreamObserver<Stat> responseObserver) {
            return computeMinMax(responseObserver, false);
          }
  
          @Override
          public StreamObserver<Monster> getMinMaxHitPoints(final StreamObserver<Stat> responseObserver) {
            return computeMinMax(responseObserver, true);
          }
  
          private StreamObserver<Monster> computeMinMax(final StreamObserver<Stat> responseObserver, final boolean includeMin) {
            final AtomicInteger maxHp = new AtomicInteger(Integer.MIN_VALUE);
            final AtomicReference<String> maxHpMonsterName = new AtomicReference<String>();
            final AtomicInteger maxHpCount = new AtomicInteger();
  
            final AtomicInteger minHp = new AtomicInteger(Integer.MAX_VALUE);
            final AtomicReference<String> minHpMonsterName = new AtomicReference<String>();
            final AtomicInteger minHpCount = new AtomicInteger();
  
            return new StreamObserver<Monster>() {
              public void onNext(Monster monster) {
                if (monster.hp() > maxHp.get()) {
                  // Found a monster of higher hit points.
                  maxHp.set(monster.hp());
                  maxHpMonsterName.set(monster.name()); 
                  maxHpCount.set(1);
                }
                else if (monster.hp() == maxHp.get()) {
                  // Count how many times we saw a monster of current max hit points.
                  maxHpCount.getAndIncrement();
                }
  
                if (monster.hp() < minHp.get()) {
                  // Found a monster of a lower hit points.
                  minHp.set(monster.hp());
                  minHpMonsterName.set(monster.name());
                  minHpCount.set(1);
                }
                else if (monster.hp() == minHp.get()) {
                  // Count how many times we saw a monster of current min hit points.
                  minHpCount.getAndIncrement();
                }
              }
              public void onCompleted() {
                Stat maxHpStat = GameFactory.createStat(maxHpMonsterName.get(), maxHp.get(), maxHpCount.get());
                // Send max hit points first.
                responseObserver.onNext(maxHpStat);
                if (includeMin) {
                  // Send min hit points.
                  Stat minHpStat = GameFactory.createStat(minHpMonsterName.get(), minHp.get(), minHpCount.get());
                  responseObserver.onNext(minHpStat);
                }
                responseObserver.onCompleted();
              }
              public void onError(Throwable t) {
                // Not expected
                Assert.fail();
              };
            };
          }
      }
  
      @org.junit.BeforeClass
      public static void startServer() throws IOException {
          server = ServerBuilder.forPort(0).addService(new MyService()).build().start();
          int port = server.getPort();
          channel = ManagedChannelBuilder.forAddress("localhost", port)
                  // Channels are secure by default (via SSL/TLS). For the example we disable TLS to avoid
                  // needing certificates.
                  .usePlaintext(true)
                  .directExecutor()
                  .build();
          blockingStub = MonsterStorageGrpc.newBlockingStub(channel);
          asyncStub = MonsterStorageGrpc.newStub(channel);
      }
  
      @org.junit.Test
      public void testUnary() throws IOException {
          Monster monsterRequest = GameFactory.createMonster(BIG_MONSTER_NAME, nestedMonsterHp, nestedMonsterMana);
          Stat stat = blockingStub.store(monsterRequest);
          Assert.assertEquals(stat.id(), "Hello " + BIG_MONSTER_NAME);
          System.out.println("Received stat response from service: " + stat.id());
      }
  
      @org.junit.Test
      public void testServerStreaming() throws IOException {
          Monster monsterRequest = GameFactory.createMonster(BIG_MONSTER_NAME, nestedMonsterHp, nestedMonsterMana);
          Stat stat = blockingStub.store(monsterRequest);
          Iterator<Monster> iterator = blockingStub.retrieve(stat);
          int counter = 0;
          while(iterator.hasNext()) {
              Monster m = iterator.next();
              System.out.println("Received monster " + m.name());
              counter ++;
          }
          Assert.assertEquals(counter, numStreamedMsgs);
          System.out.println("FlatBuffers GRPC client/server test: completed successfully");
      }
  
      @org.junit.Test
      public void testClientStreaming() throws IOException, InterruptedException {
        final AtomicReference<Stat> maxHitStat = new AtomicReference<Stat>();
        final CountDownLatch streamAlive = new CountDownLatch(1);
  
        StreamObserver<Stat> statObserver = new StreamObserver<Stat>() {
          public void onCompleted() { 
            streamAlive.countDown();
          }
          public void onError(Throwable ex) { }
          public void onNext(Stat stat) {
            maxHitStat.set(stat);
          }
        };
        StreamObserver<Monster> monsterStream = asyncStub.getMaxHitPoint(statObserver);
        short count = 10;
        for (short i = 0;i < count; ++i) {
          Monster monster = GameFactory.createMonster(BIG_MONSTER_NAME + i, (short) (nestedMonsterHp * i), nestedMonsterMana);
          monsterStream.onNext(monster);
        }
        monsterStream.onCompleted();
        // Wait a little bit for the server to send the stats of the monster with the max hit-points.
        streamAlive.await(timeoutMs, TimeUnit.MILLISECONDS);
        Assert.assertEquals(maxHitStat.get().id(), BIG_MONSTER_NAME + (count - 1));
        Assert.assertEquals(maxHitStat.get().val(), nestedMonsterHp * (count - 1));
        Assert.assertEquals(maxHitStat.get().count(), 1);
      }
  
      @org.junit.Test
      public void testBiDiStreaming() throws IOException, InterruptedException {
        final AtomicReference<Stat> maxHitStat = new AtomicReference<Stat>();
        final AtomicReference<Stat> minHitStat = new AtomicReference<Stat>();
        final CountDownLatch streamAlive = new CountDownLatch(1);
  
        StreamObserver<Stat> statObserver = new StreamObserver<Stat>() {
          public void onCompleted() {
            streamAlive.countDown();
          }
          public void onError(Throwable ex) { }
          public void onNext(Stat stat) {
            // We expect the server to send the max stat first and then the min stat.
            if (maxHitStat.get() == null) {
              maxHitStat.set(stat);
            }
            else {
              minHitStat.set(stat);
            }
          }
        };
        StreamObserver<Monster> monsterStream = asyncStub.getMinMaxHitPoints(statObserver);
        short count = 10;
        for (short i = 0;i < count; ++i) {
          Monster monster = GameFactory.createMonster(BIG_MONSTER_NAME + i, (short) (nestedMonsterHp * i), nestedMonsterMana);
          monsterStream.onNext(monster);
        }
        monsterStream.onCompleted();
  
        // Wait a little bit for the server to send the stats of the monster with the max and min hit-points.
        streamAlive.await(timeoutMs, TimeUnit.MILLISECONDS);
  
        Assert.assertEquals(maxHitStat.get().id(), BIG_MONSTER_NAME + (count - 1));
        Assert.assertEquals(maxHitStat.get().val(), nestedMonsterHp * (count - 1));
        Assert.assertEquals(maxHitStat.get().count(), 1);
  
        Assert.assertEquals(minHitStat.get().id(), BIG_MONSTER_NAME + 0);
        Assert.assertEquals(minHitStat.get().val(), nestedMonsterHp * 0);
        Assert.assertEquals(minHitStat.get().count(), 1);
      }
  }
  