content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.master;
  
  import alluxio.Registry;
  import alluxio.Server;
  import alluxio.grpc.GrpcService;
  import alluxio.grpc.ServiceType;
  
  import com.google.common.collect.ImmutableList;
  import org.junit.Assert;
  import org.junit.Test;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import javax.annotation.Nullable;
  
  public final class RegistryTest {
    public abstract static class TestServer implements Server<Void> {
      @Override
      @Nullable
      public Map<ServiceType, GrpcService> getServices() {
        return null;
      }
  
      @Override
      public void start(Void unused) throws IOException {}
  
      @Override
      public void stop() throws IOException {}
  
      @Override
      public void close() throws IOException {}
    }
  
    public class ServerA extends TestServer {
      @Override
      public String getName() {
        return "A";
      }
  
      @Override
      public Set<Class<? extends Server>> getDependencies() {
        Set<Class<? extends Server>> deps = new HashSet<>();
        deps.add(ServerB.class);
        return deps;
      }
    }
  
    public class ServerB extends TestServer {
      @Override
      public String getName() {
        return "B";
      }
  
      @Override
      public Set<Class<? extends Server>> getDependencies() {
        Set<Class<? extends Server>> deps = new HashSet<>();
        deps.add(ServerC.class);
        return deps;
      }
    }
  
    public class ServerC extends TestServer {
      @Override
      public String getName() {
        return "C";
      }
  
      @Override
      public Set<Class<? extends Server>> getDependencies() {
        Set<Class<? extends Server>> deps = new HashSet<>();
        deps.add(ServerD.class);
        return deps;
      }
    }
  
    public class ServerD extends TestServer {
      @Override
      public String getName() {
        return "C";
      }
  
      @Override
      public Set<Class<? extends Server>> getDependencies() {
        Set<Class<? extends Server>> deps = new HashSet<>();
        deps.add(ServerA.class);
        return deps;
      }
    }
  
    @Test
    public void registry() {
      List<TestServer> masters = ImmutableList.of(new ServerC(), new ServerB(), new ServerA());
      List<TestServer[]> permutations = new ArrayList<>();
      computePermutations(masters.toArray(new TestServer[0]), 0, permutations);
      // Make sure that the registry orders the masters independently of the order in which they
      // are registered.
      for (TestServer[] permutation : permutations) {
        Registry<TestServer, Void> registry = new Registry<>();
        for (TestServer server : permutation) {
          registry.add(server.getClass(), server);
        }
        Assert.assertEquals(masters, registry.getServers());
      }
    }
  
    @Test
    public void cycle() {
      Registry<TestServer, Void> registry = new Registry<>();
      registry.add(ServerA.class, new ServerA());
      registry.add(ServerB.class, new ServerB());
      registry.add(ServerC.class, new ServerC());
      registry.add(ServerC.class, new ServerD());
  
      Assert.assertThrows(RuntimeException.class, registry::getServers);
    }
  
    @Test
    public void unavailable() {
      Registry<TestServer, Void> registry = new Registry<>();
  
      Exception exception = Assert.assertThrows(Exception.class,
          () -> registry.get(ServerB.class, 100));
      Assert.assertTrue(exception.getMessage().contains("Timed out"));
      Assert.assertTrue(exception.getMessage().contains("ServerB"));
    }
  
    private void computePermutations(TestServer[] input, int index, List<TestServer[]> permutations) {
      if (index == input.length) {
        permutations.add(input.clone());
      }
      for (int i = index; i < input.length; i++) {
        TestServer tmp = input[i];
        input[i] = input[index];
        input[index] = tmp;
        computePermutations(input, index + 1, permutations);
        input[index] = input[i];
        input[i] = tmp;
      }
    }
  }
  