1 /*
2 * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
3 * Copyright (C) 2009 Google Inc. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
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 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
21 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
22 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include "config.h"
28 #include "ThreadTimers.h"
29
30 #include "SharedTimer.h"
31 #include "ThreadGlobalData.h"
32 #include "Timer.h"
33 #include <wtf/CurrentTime.h>
34
35 namespace WebCore {
36
37 // Fire timers for this length of time, and then quit to let the run loop process user input events.
38 // 100ms is about a perceptable delay in UI, so use a half of that as a threshold.
39 // This is to prevent UI freeze when there are too many timers or machine performance is low.
40 static const double maxDurationOfFiringTimers = 0.050;
41
42 // Timers are created, started and fired on the same thread, and each thread has its own ThreadTimers
43 // copy to keep the heap and a set of currently firing timers.
44
mainThreadSharedTimer()45 static MainThreadSharedTimer* mainThreadSharedTimer()
46 {
47 static MainThreadSharedTimer* timer = new MainThreadSharedTimer;
48 return timer;
49 }
50
ThreadTimers()51 ThreadTimers::ThreadTimers()
52 : m_sharedTimer(0)
53 , m_firingTimers(false)
54 {
55 if (isMainThread())
56 setSharedTimer(mainThreadSharedTimer());
57 }
58
59 // A worker thread may initialize SharedTimer after some timers are created.
60 // Also, SharedTimer can be replaced with 0 before all timers are destroyed.
setSharedTimer(SharedTimer * sharedTimer)61 void ThreadTimers::setSharedTimer(SharedTimer* sharedTimer)
62 {
63 if (m_sharedTimer) {
64 m_sharedTimer->setFiredFunction(0);
65 m_sharedTimer->stop();
66 }
67
68 m_sharedTimer = sharedTimer;
69
70 if (sharedTimer) {
71 m_sharedTimer->setFiredFunction(ThreadTimers::sharedTimerFired);
72 updateSharedTimer();
73 }
74 }
75
updateSharedTimer()76 void ThreadTimers::updateSharedTimer()
77 {
78 if (!m_sharedTimer)
79 return;
80
81 if (m_firingTimers || m_timerHeap.isEmpty())
82 m_sharedTimer->stop();
83 else
84 m_sharedTimer->setFireTime(m_timerHeap.first()->m_nextFireTime);
85 }
86
sharedTimerFired()87 void ThreadTimers::sharedTimerFired()
88 {
89 // Redirect to non-static method.
90 threadGlobalData().threadTimers().sharedTimerFiredInternal();
91 }
92
sharedTimerFiredInternal()93 void ThreadTimers::sharedTimerFiredInternal()
94 {
95 // Do a re-entrancy check.
96 if (m_firingTimers)
97 return;
98 m_firingTimers = true;
99
100 double fireTime = currentTime();
101 double timeToQuit = fireTime + maxDurationOfFiringTimers;
102
103 while (!m_timerHeap.isEmpty() && m_timerHeap.first()->m_nextFireTime <= fireTime) {
104 TimerBase* timer = m_timerHeap.first();
105 timer->m_nextFireTime = 0;
106 timer->heapDeleteMin();
107
108 double interval = timer->repeatInterval();
109 timer->setNextFireTime(interval ? fireTime + interval : 0);
110
111 // Once the timer has been fired, it may be deleted, so do nothing else with it after this point.
112 timer->fired();
113
114 // Catch the case where the timer asked timers to fire in a nested event loop, or we are over time limit.
115 if (!m_firingTimers || timeToQuit < currentTime())
116 break;
117 }
118
119 m_firingTimers = false;
120
121 updateSharedTimer();
122 }
123
fireTimersInNestedEventLoop()124 void ThreadTimers::fireTimersInNestedEventLoop()
125 {
126 // Reset the reentrancy guard so the timers can fire again.
127 m_firingTimers = false;
128 updateSharedTimer();
129 }
130
131 } // namespace WebCore
132
133