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