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.journal;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  
  /**
   * Used to track and cancel journal advancing.
   */
  public class CatchupFuture {
    /** Internal list of catch-up threads. */
    private final List<AbstractCatchupThread> mCatchupThreads;
  
    /**
     * Creates a single future for tracking a list of catchup futures.
     *
     * @param futures list of catchup futures
     * @return unified catchup future
     */
    public static CatchupFuture allOf(List<CatchupFuture> futures) {
      List<AbstractCatchupThread> threads = new ArrayList<>(futures.size());
      for (CatchupFuture future : futures) {
        threads.addAll(future.mCatchupThreads);
      }
      return new CatchupFuture(threads);
    }
  
    /**
     * @return a completed catchup future
     */
    public static CatchupFuture completed() {
      return new CatchupFuture(Collections.emptyList());
    }
  
    /**
     * Creates a tracker for given catchup thread.
     *
     * @param catchupThread journal catchup thread
     */
    public CatchupFuture(AbstractCatchupThread catchupThread) {
      mCatchupThreads = new ArrayList<>(1);
      mCatchupThreads.add(catchupThread);
    }
  
    /**
     * Used internally to manage multiple catchup threads.
     *
     * @param catchupThreads list of catchup threads
     */
    private CatchupFuture(List<AbstractCatchupThread> catchupThreads) {
      mCatchupThreads = catchupThreads;
    }
  
    /**
     * Cancels catchup progress gracefully.
     */
    public void cancel() {
      for (AbstractCatchupThread thread : mCatchupThreads) {
        thread.cancel();
      }
    }
  
    /**
     * Waits until advancing finishes.
     */
    public void waitTermination() {
      for (AbstractCatchupThread thread : mCatchupThreads) {
        thread.waitTermination();
      }
    }
  }
  