alluxio-master-2.x/core/server/common/src/main/java/alluxio/master/journal/AbstractCatchupThread.java
/*
 * 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.journal;

import alluxio.ProcessUtils;
import alluxio.thread.AutopsyThread;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Abstract helper for tracking and terminating a thread for journal catch-up task.
 */
public abstract class AbstractCatchupThread extends AutopsyThread {
  private static final Logger LOG = LoggerFactory.getLogger(AbstractCatchupThread.class);

  /**
   * Constructor.
   */
  public AbstractCatchupThread() {
    super();
  }

  @Override
  public void run() {
    try {
      runCatchup();
    } catch (Exception e) {
      setError(e);
      ProcessUtils.fatalError(LOG, e, "Catch-up thread is failed.");
    }
  }

  /**
   * Cancels catching up gracefully.
   */
  public abstract void cancel();

  /**
   * Waits until catching up is finished (completed/cancelled).
   */
  public void waitTermination() {
    try {
      // Wait until thread terminates or timeout elapses.
      join(0);
      // If the catchup failed but the process did not fail, abort the process on detection
      if (crashed()) {
        LOG.error("Thread {} has crashed before termination", Thread.currentThread().getId());
        throw new RuntimeException(getError());
      }
    } catch (Exception e) {
      ProcessUtils.fatalError(LOG, e, "Catch-up task failed.");
    }
  }

  /**
   * Does the work of catching up.
   */
  protected abstract void runCatchup();
}
