WebKitTools/DumpRenderTree/WorkQueue.cpp

   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
  35 static const unsigned queueLength = 1024;
  36
  37 static WorkQueueItem* theQueue[queueLength];
  38 static unsigned startOfQueue;
  39 static unsigned endOfQueue;
  40
  41 WorkQueue* WorkQueue::shared()
  42 {
  43     static WorkQueue* sharedInstance = new WorkQueue;
  44     return sharedInstance;
  45 }
  46
  47 WorkQueue::WorkQueue()
  48     : m_frozen(false)
  49 {
  50 }
  51
  52 void 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
  65 WorkQueueItem* WorkQueue::dequeue()
  66 {
  67     ASSERT(endOfQueue >= startOfQueue);
  68
  69     if (startOfQueue == endOfQueue)
  70         return 0;
  71
  72     return theQueue[startOfQueue++];
  73 }
  74
  75 unsigned WorkQueue::count()
  76 {
  77     return endOfQueue - startOfQueue;
  78 }
  79
  80 void 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
  91 bool 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 }