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