WorkQueue.cpp revision f05b935882198ccf7d81675736e3aeb089c5113a
1/* 2 * Copyright (C) 2007, 2009 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#include "config.h" 30#include "WorkQueue.h" 31 32#include "WorkQueueItem.h" 33#include <wtf/Assertions.h> 34 35static const unsigned queueLength = 1024; 36 37static WorkQueueItem* theQueue[queueLength]; 38static unsigned startOfQueue; 39static unsigned endOfQueue; 40 41WorkQueue* WorkQueue::shared() 42{ 43 static WorkQueue* sharedInstance = new WorkQueue; 44 return sharedInstance; 45} 46 47WorkQueue::WorkQueue() 48 : m_frozen(false) 49{ 50} 51 52void WorkQueue::queue(WorkQueueItem* item) 53{ 54 ASSERT(endOfQueue < queueLength); 55 ASSERT(endOfQueue >= startOfQueue); 56 57 if (m_frozen) { 58 delete item; 59 return; 60 } 61 62 theQueue[endOfQueue++] = item; 63} 64 65WorkQueueItem* WorkQueue::dequeue() 66{ 67 ASSERT(endOfQueue >= startOfQueue); 68 69 if (startOfQueue == endOfQueue) 70 return 0; 71 72 return theQueue[startOfQueue++]; 73} 74 75unsigned WorkQueue::count() 76{ 77 return endOfQueue - startOfQueue; 78} 79 80void WorkQueue::clear() 81{ 82 for (unsigned i = startOfQueue; i < endOfQueue; ++i) { 83 delete theQueue[i]; 84 theQueue[i] = 0; 85 } 86 87 startOfQueue = 0; 88 endOfQueue = 0; 89} 90 91bool WorkQueue::processWork() 92{ 93 bool startedLoad = false; 94 95 while (!startedLoad && count()) { 96 WorkQueueItem* item = dequeue(); 97 ASSERT(item); 98 startedLoad = item->invoke(); 99 delete item; 100 } 101 102 // If we're done and we didn't start a load, then we're really done, so return true. 103 return !startedLoad; 104} 105