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
shared()41 WorkQueue* WorkQueue::shared()
42 {
43 static WorkQueue* sharedInstance = new WorkQueue;
44 return sharedInstance;
45 }
46
WorkQueue()47 WorkQueue::WorkQueue()
48 : m_frozen(false)
49 {
50 }
51
queue(WorkQueueItem * item)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
dequeue()65 WorkQueueItem* WorkQueue::dequeue()
66 {
67 ASSERT(endOfQueue >= startOfQueue);
68
69 if (startOfQueue == endOfQueue)
70 return 0;
71
72 return theQueue[startOfQueue++];
73 }
74
count()75 unsigned WorkQueue::count()
76 {
77 return endOfQueue - startOfQueue;
78 }
79
clear()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
processWork()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 }
105