001    /*
002     * Copyright (C) 2010 The Guava Authors
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    
017    package com.google.common.util.concurrent;
018    
019    import com.google.common.collect.ForwardingQueue;
020    
021    import java.util.Collection;
022    import java.util.concurrent.BlockingQueue;
023    import java.util.concurrent.TimeUnit;
024    
025    /**
026     * A {@link BlockingQueue} which forwards all its method calls to another
027     * {@link BlockingQueue}. Subclasses should override one or more methods to
028     * modify the behavior of the backing collection as desired per the <a
029     * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
030     *
031     * @author Raimundo Mirisola
032     *
033     * @param <E> the type of elements held in this collection
034     * @since 4.0
035     */
036    public abstract class ForwardingBlockingQueue<E> extends ForwardingQueue<E>
037        implements BlockingQueue<E> {
038    
039      /** Constructor for use by subclasses. */
040      protected ForwardingBlockingQueue() {}
041    
042      @Override protected abstract BlockingQueue<E> delegate();
043    
044      @Override public int drainTo(
045          Collection<? super E> c, int maxElements) {
046        return delegate().drainTo(c, maxElements);
047      }
048    
049      @Override public int drainTo(Collection<? super E> c) {
050        return delegate().drainTo(c);
051      }
052    
053      @Override public boolean offer(E e, long timeout, TimeUnit unit)
054          throws InterruptedException {
055        return delegate().offer(e, timeout, unit);
056      }
057    
058      @Override public E poll(long timeout, TimeUnit unit)
059          throws InterruptedException {
060        return delegate().poll(timeout, unit);
061      }
062    
063      @Override public void put(E e) throws InterruptedException {
064        delegate().put(e);
065      }
066    
067      @Override public int remainingCapacity() {
068        return delegate().remainingCapacity();
069      }
070    
071      @Override public E take() throws InterruptedException {
072        return delegate().take();
073      }
074    }