001/*
002 * Copyright (C) 2012 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
017package com.google.common.util.concurrent;
018
019import com.google.common.annotations.GwtIncompatible;
020import com.google.common.annotations.J2ktIncompatible;
021import com.google.common.collect.ForwardingDeque;
022import java.util.Collection;
023import java.util.concurrent.BlockingDeque;
024import java.util.concurrent.TimeUnit;
025import org.jspecify.annotations.Nullable;
026
027/**
028 * A {@link BlockingDeque} which forwards all its method calls to another {@code BlockingDeque}.
029 * Subclasses should override one or more methods to modify the behavior of the backing deque as
030 * desired per the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
031 *
032 * <p><b>Warning:</b> The methods of {@code ForwardingBlockingDeque} forward <b>indiscriminately</b>
033 * to the methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change
034 * the behaviour of {@link #offer} which can lead to unexpected behaviour. In this case, you should
035 * override {@code offer} as well, either providing your own implementation, or delegating to the
036 * provided {@code standardOffer} method.
037 *
038 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code
039 * default} methods. Instead, it inherits their default implementations. When those implementations
040 * invoke methods, they invoke methods on the {@code ForwardingBlockingDeque}.
041 *
042 * <p>The {@code standard} methods are not guaranteed to be thread-safe, even when all of the
043 * methods that they depend on are thread-safe.
044 *
045 * @author Emily Soldal
046 * @since 21.0 (since 14.0 as {@link com.google.common.collect.ForwardingBlockingDeque})
047 */
048@J2ktIncompatible
049@GwtIncompatible
050public abstract class ForwardingBlockingDeque<E> extends ForwardingDeque<E>
051    implements BlockingDeque<E> {
052
053  /** Constructor for use by subclasses. */
054  protected ForwardingBlockingDeque() {}
055
056  @Override
057  protected abstract BlockingDeque<E> delegate();
058
059  @Override
060  public int remainingCapacity() {
061    return delegate().remainingCapacity();
062  }
063
064  @Override
065  public void putFirst(E e) throws InterruptedException {
066    delegate().putFirst(e);
067  }
068
069  @Override
070  public void putLast(E e) throws InterruptedException {
071    delegate().putLast(e);
072  }
073
074  @Override
075  public boolean offerFirst(E e, long timeout, TimeUnit unit) throws InterruptedException {
076    return delegate().offerFirst(e, timeout, unit);
077  }
078
079  @Override
080  public boolean offerLast(E e, long timeout, TimeUnit unit) throws InterruptedException {
081    return delegate().offerLast(e, timeout, unit);
082  }
083
084  @Override
085  public E takeFirst() throws InterruptedException {
086    return delegate().takeFirst();
087  }
088
089  @Override
090  public E takeLast() throws InterruptedException {
091    return delegate().takeLast();
092  }
093
094  @Override
095  public @Nullable E pollFirst(long timeout, TimeUnit unit) throws InterruptedException {
096    return delegate().pollFirst(timeout, unit);
097  }
098
099  @Override
100  public @Nullable E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
101    return delegate().pollLast(timeout, unit);
102  }
103
104  @Override
105  public void put(E e) throws InterruptedException {
106    delegate().put(e);
107  }
108
109  @Override
110  public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedException {
111    return delegate().offer(e, timeout, unit);
112  }
113
114  @Override
115  public E take() throws InterruptedException {
116    return delegate().take();
117  }
118
119  @Override
120  public @Nullable E poll(long timeout, TimeUnit unit) throws InterruptedException {
121    return delegate().poll(timeout, unit);
122  }
123
124  @Override
125  public int drainTo(Collection<? super E> c) {
126    return delegate().drainTo(c);
127  }
128
129  @Override
130  public int drainTo(Collection<? super E> c, int maxElements) {
131    return delegate().drainTo(c, maxElements);
132  }
133}