1 /* 2 * Copyright (C) 2012 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.common.collect; 18 19 import java.util.Collection; 20 import java.util.concurrent.BlockingDeque; 21 import java.util.concurrent.TimeUnit; 22 23 /** 24 * A {@link BlockingDeque} which forwards all its method calls to another {@code BlockingDeque}. 25 * Subclasses should override one or more methods to modify the behavior of the backing deque as 26 * desired per the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>. 27 * 28 * <p><b>Warning:</b> The methods of {@code ForwardingBlockingDeque} forward 29 * <b>indiscriminately</b> to the methods of the delegate. For example, overriding {@link #add} 30 * alone <b>will not</b> change the behaviour of {@link #offer} which can lead to unexpected 31 * behaviour. In this case, you should override {@code offer} as well, either providing your own 32 * implementation, or delegating to the provided {@code standardOffer} method. 33 * 34 * <p> 35 * The {@code standard} methods are not guaranteed to be thread-safe, even when all of the methods 36 * that they depend on are thread-safe. 37 * 38 * @author Emily Soldal 39 * @since 14.0 40 */ 41 public abstract class ForwardingBlockingDeque<E> 42 extends ForwardingDeque<E> implements BlockingDeque<E> { 43 44 /** Constructor for use by subclasses. */ ForwardingBlockingDeque()45 protected ForwardingBlockingDeque() {} 46 delegate()47 @Override protected abstract BlockingDeque<E> delegate(); 48 49 @Override remainingCapacity()50 public int remainingCapacity() { 51 return delegate().remainingCapacity(); 52 } 53 54 @Override putFirst(E e)55 public void putFirst(E e) throws InterruptedException { 56 delegate().putFirst(e); 57 } 58 59 @Override putLast(E e)60 public void putLast(E e) throws InterruptedException { 61 delegate().putLast(e); 62 } 63 64 @Override offerFirst(E e, long timeout, TimeUnit unit)65 public boolean offerFirst(E e, long timeout, TimeUnit unit) throws InterruptedException { 66 return delegate().offerFirst(e, timeout, unit); 67 } 68 69 @Override offerLast(E e, long timeout, TimeUnit unit)70 public boolean offerLast(E e, long timeout, TimeUnit unit) throws InterruptedException { 71 return delegate().offerLast(e, timeout, unit); 72 } 73 74 @Override takeFirst()75 public E takeFirst() throws InterruptedException { 76 return delegate().takeFirst(); 77 } 78 79 @Override takeLast()80 public E takeLast() throws InterruptedException { 81 return delegate().takeLast(); 82 } 83 84 @Override pollFirst(long timeout, TimeUnit unit)85 public E pollFirst(long timeout, TimeUnit unit) throws InterruptedException { 86 return delegate().pollFirst(timeout, unit); 87 } 88 89 @Override pollLast(long timeout, TimeUnit unit)90 public E pollLast(long timeout, TimeUnit unit) throws InterruptedException { 91 return delegate().pollLast(timeout, unit); 92 } 93 94 @Override put(E e)95 public void put(E e) throws InterruptedException { 96 delegate().put(e); 97 } 98 99 @Override offer(E e, long timeout, TimeUnit unit)100 public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedException { 101 return delegate().offer(e, timeout, unit); 102 } 103 104 @Override take()105 public E take() throws InterruptedException { 106 return delegate().take(); 107 } 108 109 @Override poll(long timeout, TimeUnit unit)110 public E poll(long timeout, TimeUnit unit) throws InterruptedException { 111 return delegate().poll(timeout, unit); 112 } 113 114 @Override drainTo(Collection<? super E> c)115 public int drainTo(Collection<? super E> c) { 116 return delegate().drainTo(c); 117 } 118 119 @Override drainTo(Collection<? super E> c, int maxElements)120 public int drainTo(Collection<? super E> c, int maxElements) { 121 return delegate().drainTo(c, maxElements); 122 } 123 } 124