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.selectionpolicy;
  
  import alluxio.exception.status.UnavailableException;
  import alluxio.master.MasterInquireClient;
  
  import java.net.InetSocketAddress;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.List;
  import java.util.Random;
  import javax.annotation.Nullable;
  
  /**
   * The master connection mode that connects to a random standby master.
   */
  public class SelectionPolicyAnyStandbyMaster extends AbstractMasterSelectionPolicy {
    @Nullable
    private final Random mRandom;
  
    /**
     * Creates a new standby connection mode that picks the standby master randomly.
     */
    protected SelectionPolicyAnyStandbyMaster() {
      mRandom = null;
    }
  
    /**
     * Creates a new standby connection mode that
     * picks the standby master deterministically with a random seed.
     *
     * @param shuffleSeed the random seed to shuffle the master client list
     */
    protected SelectionPolicyAnyStandbyMaster(long shuffleSeed) {
      mRandom = new Random(shuffleSeed);
    }
  
    @Override
    public synchronized InetSocketAddress getGrpcMasterAddress(
        MasterInquireClient masterInquireClient) throws UnavailableException {
      List<InetSocketAddress> masterAddresses =
          new ArrayList<>(masterInquireClient.getMasterRpcAddresses());
  
      if (mRandom != null) {
        masterAddresses.sort(Comparator.comparing(InetSocketAddress::toString));
        Collections.shuffle(masterAddresses, mRandom);
      } else {
        Collections.shuffle(masterAddresses);
      }
      for (InetSocketAddress address : masterAddresses) {
        if (!address.equals(getPrimaryMasterAddressCached(masterInquireClient))) {
          return address;
        }
      }
      throw new UnavailableException("No standby masters available");
    }
  
    @Override
    public Type getType() {
      return Type.ANY_STANDBY_MASTER;
    }
  }
  