ClientFuture.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.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);
      }
   }
}