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 javax.annotation.Nullable;
  
  /**
   * Base class of master selection policy that
   * determines which master node a client should connect to.
   */
  public abstract class AbstractMasterSelectionPolicy implements MasterSelectionPolicy {
    @Nullable
    protected volatile InetSocketAddress mPrimaryMasterAddress;
  
    @Override
    public synchronized InetSocketAddress getPrimaryMasterAddressCached(
        MasterInquireClient masterInquireClient) throws UnavailableException {
      if (mPrimaryMasterAddress == null) {
        mPrimaryMasterAddress = masterInquireClient.getPrimaryRpcAddress();
      }
      return mPrimaryMasterAddress;
    }
  
    @Override
    public abstract InetSocketAddress getGrpcMasterAddress(MasterInquireClient masterInquireClient)
        throws UnavailableException;
  
    @Override
    public synchronized void resetPrimaryMasterAddressCache() {
      mPrimaryMasterAddress = null;
    }
  }
  