MessageBlockingQueueFactory.java

/*
 * Copyright (C) 2013 Google Inc.
 *
 * Licensed 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.ros.concurrent;

import java.util.concurrent.ArrayBlockingQueue;

/**
 * Class for getting a {@link MessageBlockingQueue}.
 *
 * @author Keith M. Hughes
 */
public class MessageBlockingQueueFactory {

  /**
   * Get a new {@link MessageBlockingQueue}.
   *
   * @param capacity
   *          base capacity of the queue
   * @param finite
   *          {@code true} if the queue should be finite and drop messages when full
   *
   * @return an implementation giving the requested features
   */
  public static <T> MessageBlockingQueue<T> newMessageBlockingQueue(final int capacity,
      boolean finite) {
    if (finite) {
      return new MessageBlockingQueue<T>() {
        // The circular queue
        private CircularBlockingDeque<T> deque = new CircularBlockingDeque<T>(capacity);

        @Override
        public T take() throws InterruptedException {
          return deque.takeFirst();
        }

        @Override
        public T poll() {
          return deque.poll();
        }

        @Override
        public void put(T entry) {
          deque.addLast(entry);
        }

        @Override
        public boolean isEmpty() {
          return deque.isEmpty();
        }
      };
    } else {
      return new MessageBlockingQueue<T>() {
        // The circular queue
        private ArrayBlockingQueue<T> queue = new ArrayBlockingQueue<T>(capacity);

        @Override
        public T take() throws InterruptedException {
          return queue.take();
        }

        @Override
        public T poll() {
          return queue.poll();
        }

        @Override
        public void put(T entry) throws InterruptedException {
          queue.put(entry);
        }

        @Override
        public boolean isEmpty() {
          return queue.isEmpty();
        }
      };
    }
  }
}