1 /* 2 * Copyright (C) 2008 Apple Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of 14 * its contributors may be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY 18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY 21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #ifndef MessageQueue_h 30 #define MessageQueue_h 31 32 #include <wtf/Assertions.h> 33 #include <wtf/Deque.h> 34 #include <wtf/Noncopyable.h> 35 #include <wtf/Threading.h> 36 37 namespace WTF { 38 39 enum MessageQueueWaitResult { 40 MessageQueueTerminated, // Queue was destroyed while waiting for message. 41 MessageQueueTimeout, // Timeout was specified and it expired. 42 MessageQueueMessageReceived, // A message was successfully received and returned. 43 }; 44 45 template<typename DataType> 46 class MessageQueue : Noncopyable { 47 public: MessageQueue()48 MessageQueue() : m_killed(false) {} 49 50 void append(const DataType&); 51 void prepend(const DataType&); 52 bool waitForMessage(DataType&); 53 MessageQueueWaitResult waitForMessageTimed(DataType&, double absoluteTime); 54 void kill(); 55 56 bool tryGetMessage(DataType&); 57 bool killed() const; 58 59 // The result of isEmpty() is only valid if no other thread is manipulating the queue at the same time. 60 bool isEmpty(); 61 62 private: 63 mutable Mutex m_mutex; 64 ThreadCondition m_condition; 65 Deque<DataType> m_queue; 66 bool m_killed; 67 }; 68 69 template<typename DataType> append(const DataType & message)70 inline void MessageQueue<DataType>::append(const DataType& message) 71 { 72 MutexLocker lock(m_mutex); 73 m_queue.append(message); 74 m_condition.signal(); 75 } 76 77 template<typename DataType> prepend(const DataType & message)78 inline void MessageQueue<DataType>::prepend(const DataType& message) 79 { 80 MutexLocker lock(m_mutex); 81 m_queue.prepend(message); 82 m_condition.signal(); 83 } 84 85 template<typename DataType> waitForMessage(DataType & result)86 inline bool MessageQueue<DataType>::waitForMessage(DataType& result) 87 { 88 MutexLocker lock(m_mutex); 89 90 while (!m_killed && m_queue.isEmpty()) 91 m_condition.wait(m_mutex); 92 93 if (m_killed) 94 return false; 95 96 ASSERT(!m_queue.isEmpty()); 97 result = m_queue.first(); 98 m_queue.removeFirst(); 99 return true; 100 } 101 102 template<typename DataType> waitForMessageTimed(DataType & result,double absoluteTime)103 inline MessageQueueWaitResult MessageQueue<DataType>::waitForMessageTimed(DataType& result, double absoluteTime) 104 { 105 MutexLocker lock(m_mutex); 106 bool timedOut = false; 107 108 while (!m_killed && !timedOut && m_queue.isEmpty()) 109 timedOut = !m_condition.timedWait(m_mutex, absoluteTime); 110 111 if (m_killed) 112 return MessageQueueTerminated; 113 114 if (timedOut) 115 return MessageQueueTimeout; 116 117 ASSERT(!m_queue.isEmpty()); 118 result = m_queue.first(); 119 m_queue.removeFirst(); 120 return MessageQueueMessageReceived; 121 } 122 123 template<typename DataType> tryGetMessage(DataType & result)124 inline bool MessageQueue<DataType>::tryGetMessage(DataType& result) 125 { 126 MutexLocker lock(m_mutex); 127 if (m_killed) 128 return false; 129 if (m_queue.isEmpty()) 130 return false; 131 132 result = m_queue.first(); 133 m_queue.removeFirst(); 134 return true; 135 } 136 137 template<typename DataType> isEmpty()138 inline bool MessageQueue<DataType>::isEmpty() 139 { 140 MutexLocker lock(m_mutex); 141 if (m_killed) 142 return true; 143 return m_queue.isEmpty(); 144 } 145 146 template<typename DataType> kill()147 inline void MessageQueue<DataType>::kill() 148 { 149 MutexLocker lock(m_mutex); 150 m_killed = true; 151 m_condition.broadcast(); 152 } 153 154 template<typename DataType> killed()155 inline bool MessageQueue<DataType>::killed() const 156 { 157 MutexLocker lock(m_mutex); 158 return m_killed; 159 } 160 } 161 162 using WTF::MessageQueue; 163 // MessageQueueWaitResult enum and all its values. 164 using WTF::MessageQueueWaitResult; 165 using WTF::MessageQueueTerminated; 166 using WTF::MessageQueueTimeout; 167 using WTF::MessageQueueMessageReceived; 168 169 #endif // MessageQueue_h 170