xref: /external/guava/guava/src/com/google/common/collect/ForwardingBlockingDeque.java

/*
 * Copyright (C) 2012 The Guava Authors
 *
 * 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 com.google.common.collect;

import java.util.Collection;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.TimeUnit;

/**
 * A {@link BlockingDeque} which forwards all its method calls to another {@code BlockingDeque}.
 * Subclasses should override one or more methods to modify the behavior of the backing deque as
 * desired per the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingBlockingDeque} forward
 * <b>indiscriminately</b> to the methods of the delegate. For example, overriding {@link #add}
 * alone <b>will not</b> change the behaviour of {@link #offer} which can lead to unexpected
 * behaviour. In this case, you should override {@code offer} as well, either providing your own
 * implementation, or delegating to the provided {@code standardOffer} method.
 *
 * <p>
 * The {@code standard} methods are not guaranteed to be thread-safe, even when all of the methods
 * that they depend on are thread-safe.
 *
 * @author Emily Soldal
 * @since 14.0
 */
public abstract class ForwardingBlockingDeque<E>
    extends ForwardingDeque<E> implements BlockingDeque<E> {

  /** Constructor for use by subclasses. */
  protected ForwardingBlockingDeque() {}

  @Override protected abstract BlockingDeque<E> delegate();

  @Override
  public int remainingCapacity() {
    return delegate().remainingCapacity();
  }

  @Override
  public void putFirst(E e) throws InterruptedException {
    delegate().putFirst(e);
  }

  @Override
  public void putLast(E e) throws InterruptedException {
    delegate().putLast(e);
  }

  @Override
  public boolean offerFirst(E e, long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().offerFirst(e, timeout, unit);
  }

  @Override
  public boolean offerLast(E e, long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().offerLast(e, timeout, unit);
  }

  @Override
  public E takeFirst() throws InterruptedException {
    return delegate().takeFirst();
  }

  @Override
  public E takeLast() throws InterruptedException {
    return delegate().takeLast();
  }

  @Override
  public E pollFirst(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().pollFirst(timeout, unit);
  }

  @Override
  public E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().pollLast(timeout, unit);
  }

  @Override
  public void put(E e) throws InterruptedException {
    delegate().put(e);
  }

  @Override
  public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().offer(e, timeout, unit);
  }

  @Override
  public E take() throws InterruptedException {
    return delegate().take();
  }

  @Override
  public E poll(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().poll(timeout, unit);
  }

  @Override
  public int drainTo(Collection<? super E> c) {
    return delegate().drainTo(c);
  }

  @Override
  public int drainTo(Collection<? super E> c, int maxElements) {
    return delegate().drainTo(c, maxElements);
  }
}