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.proxy;
  
  import alluxio.heartbeat.HeartbeatExecutor;
  import alluxio.master.MasterClientContext;
  import alluxio.wire.Address;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.time.Instant;
  import javax.annotation.concurrent.NotThreadSafe;
  
  /**
   * The Proxy will maintain a stateless heartbeat with the primary master.
   * This enables the admin to list all living Proxy instances in the cluster.
   */
  @NotThreadSafe
  public final class ProxyMasterSync implements HeartbeatExecutor {
    private static final Logger LOG = LoggerFactory.getLogger(ProxyMasterSync.class);
  
    /** The address of this proxy. */
    private final Address mAddress;
  
    /** Client for communication with the primary master. */
    private final RetryHandlingMetaMasterProxyClient mMasterClient;
  
    /**
     * Creates a new instance of {@link ProxyMasterSync}.
     *
     * @param address the proxy address
     * @param context the communication context
     * @param startTimeMs start time of this instance
     */
    public ProxyMasterSync(Address address, MasterClientContext context, long startTimeMs) {
      mAddress = address;
      mMasterClient = new RetryHandlingMetaMasterProxyClient(mAddress, context, startTimeMs);
      LOG.info("Proxy start time is {}", Instant.ofEpochMilli(startTimeMs));
    }
  
    /**
     * Heartbeats to the primary master node.
     */
    @Override
    public void heartbeat(long timeLimitMs) {
      try {
        LOG.debug("Heart beating to primary master");
        mMasterClient.proxyHeartbeat();
      } catch (IOException e) {
        // Log the error but do not shut down the proxy
        LOG.error("Failed to heartbeat to primary master", e);
        mMasterClient.disconnect();
      }
    }
  
    @Override
    public void close() {}
  }
  