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 "platform/ThreadTimers.h"
29
30 #include "platform/SharedTimer.h"
31 #include "platform/PlatformThreadData.h"
32 #include "platform/Timer.h"
33 #include "platform/TraceEvent.h"
34 #include "wtf/CurrentTime.h"
35 #include "wtf/MainThread.h"
36
37 using namespace std;
38
39 namespace WebCore {
40
41 // Fire timers for this length of time, and then quit to let the run loop process user input events.
42 // 100ms is about a perceptable delay in UI, so use a half of that as a threshold.
43 // This is to prevent UI freeze when there are too many timers or machine performance is low.
44 static const double maxDurationOfFiringTimers = 0.050;
45
46 // Timers are created, started and fired on the same thread, and each thread has its own ThreadTimers
47 // copy to keep the heap and a set of currently firing timers.
48
mainThreadSharedTimer()49 static MainThreadSharedTimer* mainThreadSharedTimer()
50 {
51 static MainThreadSharedTimer* timer = new MainThreadSharedTimer;
52 return timer;
53 }
54
ThreadTimers()55 ThreadTimers::ThreadTimers()
56 : m_sharedTimer(0)
57 , m_firingTimers(false)
58 , m_pendingSharedTimerFireTime(0)
59 {
60 if (isMainThread())
61 setSharedTimer(mainThreadSharedTimer());
62 }
63
64 // A worker thread may initialize SharedTimer after some timers are created.
65 // Also, SharedTimer can be replaced with 0 before all timers are destroyed.
setSharedTimer(SharedTimer * sharedTimer)66 void ThreadTimers::setSharedTimer(SharedTimer* sharedTimer)
67 {
68 if (m_sharedTimer) {
69 m_sharedTimer->setFiredFunction(0);
70 m_sharedTimer->stop();
71 m_pendingSharedTimerFireTime = 0;
72 }
73
74 m_sharedTimer = sharedTimer;
75
76 if (sharedTimer) {
77 m_sharedTimer->setFiredFunction(ThreadTimers::sharedTimerFired);
78 updateSharedTimer();
79 }
80 }
81
updateSharedTimer()82 void ThreadTimers::updateSharedTimer()
83 {
84 if (!m_sharedTimer)
85 return;
86
87 if (m_firingTimers || m_timerHeap.isEmpty()) {
88 m_pendingSharedTimerFireTime = 0;
89 m_sharedTimer->stop();
90 } else {
91 double nextFireTime = m_timerHeap.first()->m_nextFireTime;
92 double currentMonotonicTime = monotonicallyIncreasingTime();
93 if (m_pendingSharedTimerFireTime) {
94 // No need to restart the timer if both the pending fire time and the new fire time are in the past.
95 if (m_pendingSharedTimerFireTime <= currentMonotonicTime && nextFireTime <= currentMonotonicTime)
96 return;
97 }
98 m_pendingSharedTimerFireTime = nextFireTime;
99 m_sharedTimer->setFireInterval(max(nextFireTime - currentMonotonicTime, 0.0));
100 }
101 }
102
sharedTimerFired()103 void ThreadTimers::sharedTimerFired()
104 {
105 TRACE_EVENT_SET_SAMPLING_STATE("Blink", "BlinkInternal");
106
107 // Redirect to non-static method.
108 PlatformThreadData::current().threadTimers().sharedTimerFiredInternal();
109
110 TRACE_EVENT_SET_SAMPLING_STATE("Blink", "Sleeping");
111 }
112
sharedTimerFiredInternal()113 void ThreadTimers::sharedTimerFiredInternal()
114 {
115 // Do a re-entrancy check.
116 if (m_firingTimers)
117 return;
118 m_firingTimers = true;
119 m_pendingSharedTimerFireTime = 0;
120
121 double fireTime = monotonicallyIncreasingTime();
122 double timeToQuit = fireTime + maxDurationOfFiringTimers;
123
124 while (!m_timerHeap.isEmpty() && m_timerHeap.first()->m_nextFireTime <= fireTime) {
125 TimerBase& timer = *m_timerHeap.first();
126 timer.m_nextFireTime = 0;
127 timer.m_unalignedNextFireTime = 0;
128 timer.heapDeleteMin();
129
130 double interval = timer.repeatInterval();
131 timer.setNextFireTime(interval ? fireTime + interval : 0);
132
133 TRACE_EVENT2("blink", "ThreadTimers::sharedTimerFiredInternal",
134 "src_file", timer.location().fileName(),
135 "src_func", timer.location().functionName());
136
137 // Once the timer has been fired, it may be deleted, so do nothing else with it after this point.
138 timer.fired();
139
140 // Catch the case where the timer asked timers to fire in a nested event loop, or we are over time limit.
141 if (!m_firingTimers || timeToQuit < monotonicallyIncreasingTime())
142 break;
143 }
144
145 m_firingTimers = false;
146
147 updateSharedTimer();
148 }
149
fireTimersInNestedEventLoop()150 void ThreadTimers::fireTimersInNestedEventLoop()
151 {
152 // Reset the reentrancy guard so the timers can fire again.
153 m_firingTimers = false;
154 updateSharedTimer();
155 }
156
157 } // namespace WebCore
158
159