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;
  
  /**
   * Interface for master selection policy that
   * determines which master node a client should connect to.
   */
  public interface MasterSelectionPolicy {
    /**
     * The enum for master selection policies.
     */
    enum Type {
      PRIMARY_MASTER,
      ANY_STANDBY_MASTER,
      ANY_MASTER,
      SPECIFIED_MASTER,
    }
  
    /**
     * Get and cache the primary master address.
     *
     * @param masterInquireClient master inquire client
     *
     * @return the remote address of primary master gRPC server
     * @throws UnavailableException if address cannot be determined
     */
    InetSocketAddress getPrimaryMasterAddressCached(MasterInquireClient masterInquireClient)
        throws UnavailableException;
  
    /**
     * Gets the master address the client makes gRPC request to.
     *
     * @param masterInquireClient master inquire client
     *
     * @return the remote address of master gRPC server
     * @throws UnavailableException if address cannot be determined
     */
    InetSocketAddress getGrpcMasterAddress(MasterInquireClient masterInquireClient)
        throws UnavailableException;
  
    /**
     * Resets the cached primary master address.
     */
    void resetPrimaryMasterAddressCache();
  
    /**
     * @return the type of the master selection policy
     */
    Type getType();
  
    /**
     * Factory for {@link MasterSelectionPolicy}.
     */
    class Factory {
      /**
       * Creates a MasterSelectionPolicy that selects the primary master to connect.
       * @return the MasterSelectionPolicy
       */
      public static MasterSelectionPolicy primaryMaster() {
        return new SelectionPolicyPrimaryMaster();
      }
  
      /**
       * Creates a MasterSelectionPolicy that selects a standby master to connect.
       * @return the MasterSelectionPolicy
       */
      public static MasterSelectionPolicy anyStandbyMaster() {
        return new SelectionPolicyAnyStandbyMaster();
      }
  
      /**
       * Creates a MasterSelectionPolicy that selects a standby master to connect.
       * @param randomSeed a random seed to do the deterministic random selection
       * @return the MasterSelectionPolicy
       */
      public static MasterSelectionPolicy anyStandbyMaster(long randomSeed) {
        return new SelectionPolicyAnyStandbyMaster(randomSeed);
      }
  
      /**
       * Creates a MasterSelectionPolicy that selects a random master to connect.
       * @return the MasterSelectionPolicy
       */
      public static MasterSelectionPolicy anyMaster() {
        return new SelectionPolicyAnyMaster();
      }
  
      /**
       * Creates a MasterSelectionPolicy that selects a specified master to connect.
       * @param masterAddress the master address to connect
       * @return the MasterSelectionPolicy
       */
      public static MasterSelectionPolicy specifiedMaster(InetSocketAddress masterAddress) {
        return new SelectionPolicySpecifiedMaster(masterAddress);
      }
    }
  }
  