001/*
002 * Copyright (C) 2010 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.util.concurrent;
016
017import com.google.common.annotations.GwtIncompatible;
018import com.google.common.annotations.J2ktIncompatible;
019import com.google.common.collect.ForwardingQueue;
020import com.google.errorprone.annotations.CanIgnoreReturnValue;
021import java.util.Collection;
022import java.util.concurrent.BlockingQueue;
023import java.util.concurrent.TimeUnit;
024import org.checkerframework.checker.nullness.qual.Nullable;
025
026/**
027 * A {@link BlockingQueue} which forwards all its method calls to another {@link BlockingQueue}.
028 * Subclasses should override one or more methods to modify the behavior of the backing collection
029 * as desired per the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator
030 * pattern</a>.
031 *
032 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code
033 * default} methods. Instead, it inherits their default implementations. When those implementations
034 * invoke methods, they invoke methods on the {@code ForwardingBlockingQueue}.
035 *
036 * @author Raimundo Mirisola
037 * @param <E> the type of elements held in this collection
038 * @since 4.0
039 */
040@J2ktIncompatible
041@GwtIncompatible
042public abstract class ForwardingBlockingQueue<E> extends ForwardingQueue<E>
043    implements BlockingQueue<E> {
044
045  /** Constructor for use by subclasses. */
046  protected ForwardingBlockingQueue() {}
047
048  @Override
049  protected abstract BlockingQueue<E> delegate();
050
051  @CanIgnoreReturnValue
052  @Override
053  public int drainTo(Collection<? super E> c, int maxElements) {
054    return delegate().drainTo(c, maxElements);
055  }
056
057  @CanIgnoreReturnValue
058  @Override
059  public int drainTo(Collection<? super E> c) {
060    return delegate().drainTo(c);
061  }
062
063  @CanIgnoreReturnValue // TODO(kak): consider removing this
064  @Override
065  public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedException {
066    return delegate().offer(e, timeout, unit);
067  }
068
069  @CanIgnoreReturnValue // TODO(kak): consider removing this
070  @Override
071  public @Nullable E poll(long timeout, TimeUnit unit) throws InterruptedException {
072    return delegate().poll(timeout, unit);
073  }
074
075  @Override
076  public void put(E e) throws InterruptedException {
077    delegate().put(e);
078  }
079
080  @Override
081  public int remainingCapacity() {
082    return delegate().remainingCapacity();
083  }
084
085  @CanIgnoreReturnValue // TODO(kak): consider removing this
086  @Override
087  public E take() throws InterruptedException {
088    return delegate().take();
089  }
090}