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 javax.annotation.CheckForNull; 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 042@ElementTypesAreNonnullByDefault 043public abstract class ForwardingBlockingQueue<E> extends ForwardingQueue<E> 044 implements BlockingQueue<E> { 045 046 /** Constructor for use by subclasses. */ 047 protected ForwardingBlockingQueue() {} 048 049 @Override 050 protected abstract BlockingQueue<E> delegate(); 051 052 @CanIgnoreReturnValue 053 @Override 054 public int drainTo(Collection<? super E> c, int maxElements) { 055 return delegate().drainTo(c, maxElements); 056 } 057 058 @CanIgnoreReturnValue 059 @Override 060 public int drainTo(Collection<? super E> c) { 061 return delegate().drainTo(c); 062 } 063 064 @CanIgnoreReturnValue // TODO(kak): consider removing this 065 @Override 066 public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedException { 067 return delegate().offer(e, timeout, unit); 068 } 069 070 @CanIgnoreReturnValue // TODO(kak): consider removing this 071 @Override 072 @CheckForNull 073 public E poll(long timeout, TimeUnit unit) throws InterruptedException { 074 return delegate().poll(timeout, unit); 075 } 076 077 @Override 078 public void put(E e) throws InterruptedException { 079 delegate().put(e); 080 } 081 082 @Override 083 public int remainingCapacity() { 084 return delegate().remainingCapacity(); 085 } 086 087 @CanIgnoreReturnValue // TODO(kak): consider removing this 088 @Override 089 public E take() throws InterruptedException { 090 return delegate().take(); 091 } 092}