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.clock.ElapsedTimeClock;
  import alluxio.conf.Configuration;
  import alluxio.conf.PropertyKey;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.time.Clock;
  import java.util.concurrent.atomic.AtomicMarkableReference;
  
  /**
   * Manages safe mode state for Alluxio master.
   */
  public class DefaultSafeModeManager implements SafeModeManager {
    private static final Logger LOG = LoggerFactory.getLogger(DefaultSafeModeManager.class);
  
    private final Clock mClock;
  
    /**
     * Safe mode state. The mark indicates whether master is in safe mode, the reference stores
     * time point in millisecond indicating when master started waiting for workers.
     */
    private final AtomicMarkableReference<Long> mWorkerConnectWaitStartTimeMs =
        new AtomicMarkableReference<>(null, true);
  
    /**
     * Creates {@link DefaultSafeModeManager} with default clock.
     */
    public DefaultSafeModeManager() {
      this(new ElapsedTimeClock());
    }
  
    /**
     * Creates {@link DefaultSafeModeManager} with given clock.
     *
     * @param clock a {@link Clock} for calculating elapsed time
     */
    public DefaultSafeModeManager(Clock clock) {
      mClock = clock;
    }
  
    @Override
    public void notifyPrimaryMasterStarted() {
      mWorkerConnectWaitStartTimeMs.set(null, true);
    }
  
    @Override
    public void notifyRpcServerStarted() {
      // updates start time when Alluxio master waits for workers to register
      long waitTime = Configuration.getMs(PropertyKey.MASTER_WORKER_CONNECT_WAIT_TIME);
      LOG.info(String.format("Rpc server started, waiting %dms for workers to register", waitTime));
      mWorkerConnectWaitStartTimeMs.set(mClock.millis(), true);
    }
  
    @Override
    public boolean isInSafeMode() {
      // bails out early before expensive clock checks
      if (!mWorkerConnectWaitStartTimeMs.isMarked()) {
        return false;
      }
  
      Long startTime = mWorkerConnectWaitStartTimeMs.getReference();
      if (startTime == null) {
        // master has not started waiting for workers yet
        return true;
      }
  
      // lazily updates safe mode state upon inquiry
      long waitTime = Configuration.getMs(PropertyKey.MASTER_WORKER_CONNECT_WAIT_TIME);
      if (mClock.millis() - startTime < waitTime) {
        return true;
      }
  
      if (mWorkerConnectWaitStartTimeMs.compareAndSet(startTime, null, true, false)) {
        LOG.debug("Exiting safe mode.");
      }
  
      return mWorkerConnectWaitStartTimeMs.isMarked();
    }
  }
  