geode-core/src/main/java/org/apache/geode/internal/util/DelayedAction.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional information regarding
 * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License. You may obtain a
 * copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package org.apache.geode.internal.util;

import java.util.concurrent.CountDownLatch;

/**
 * Coordinates thread scheduling to simplify multi-threaded testing. Ensures that two threads have
 * both reached expected code before proceeding. Unlike a barrier pattern, the threads can be
 * allowed to proceed independently.
 *
 */
public class DelayedAction implements Runnable {
  private final CountDownLatch hit = new CountDownLatch(1);
  private final CountDownLatch run = new CountDownLatch(1);

  private final Runnable delayedAction;

  public DelayedAction(Runnable action) {
    delayedAction = action;
  }

  @Override
  public void run() {
    hit.countDown();
    try {
      run.await();
      if (delayedAction != null) {
        delayedAction.run();
      }
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
    }
  }

  /**
   * Blocks until the delayed action is ready to be executed.
   *
   * @throws InterruptedException interrupted while waiting
   */
  public void waitForArrival() throws InterruptedException {
    hit.await();
  }

  /**
   * Allows the delayed action to proceed when ready.
   */
  public void allowToProceed() {
    run.countDown();
  }
}