content: /**
   * 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.activemq.transport.amqp.client.util;
  
  import java.io.IOException;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicBoolean;
  
  /**
   * Asynchronous Client Future class.
   */
  public class ClientFuture implements AsyncResult {
  
      private final AtomicBoolean completer = new AtomicBoolean();
      private final CountDownLatch latch = new CountDownLatch(1);
      private final ClientFutureSynchronization synchronization;
      private volatile Throwable error;
  
      public ClientFuture() {
          this(null);
      }
  
      public ClientFuture(ClientFutureSynchronization synchronization) {
          this.synchronization = synchronization;
      }
  
      @Override
      public boolean isComplete() {
          return latch.getCount() == 0;
      }
  
      @Override
      public void onFailure(Throwable result) {
          if (completer.compareAndSet(false, true)) {
              error = result;
              if (synchronization != null) {
                  synchronization.onPendingFailure(error);
              }
              latch.countDown();
          }
      }
  
      @Override
      public void onSuccess() {
          if (completer.compareAndSet(false, true)) {
              if (synchronization != null) {
                  synchronization.onPendingSuccess();
              }
              latch.countDown();
          }
      }
  
      /**
       * Timed wait for a response to a pending operation.
       *
       * @param amount
       *        The amount of time to wait before abandoning the wait.
       * @param unit
       *        The unit to use for this wait period.
       *
       * @throws IOException if an error occurs while waiting for the response.
       */
      public void sync(long amount, TimeUnit unit) throws IOException {
          try {
              latch.await(amount, unit);
          } catch (InterruptedException e) {
              Thread.interrupted();
              throw IOExceptionSupport.create(e);
          }
  
          failOnError();
      }
  
      /**
       * Waits for a response to some pending operation.
       *
       * @throws IOException if an error occurs while waiting for the response.
       */
      public void sync() throws IOException {
          try {
              latch.await();
          } catch (InterruptedException e) {
              Thread.interrupted();
              throw IOExceptionSupport.create(e);
          }
  
          failOnError();
      }
  
      private void failOnError() throws IOException {
          Throwable cause = error;
          if (cause != null) {
              throw IOExceptionSupport.create(cause);
          }
      }
  }
  