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28 #include "platform/ThreadTimers.h"
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"
42 // Fire timers for this length of time, and then quit to let the run loop process user input events.
43 // 100ms is about a perceptable delay in UI, so use a half of that as a threshold.
44 // This is to prevent UI freeze when there are too many timers or machine performance is low.
45 static const double maxDurationOfFiringTimers = 0.050;
47 // Timers are created, started and fired on the same thread, and each thread has its own ThreadTimers
48 // copy to keep the heap and a set of currently firing timers.
50 static MainThreadSharedTimer* mainThreadSharedTimer()
52 static MainThreadSharedTimer* timer = new MainThreadSharedTimer;
56 ThreadTimers::ThreadTimers()
58 , m_firingTimers(false)
59 , m_pendingSharedTimerFireTime(0)
62 setSharedTimer(mainThreadSharedTimer());
65 // A worker thread may initialize SharedTimer after some timers are created.
66 // Also, SharedTimer can be replaced with 0 before all timers are destroyed.
67 void ThreadTimers::setSharedTimer(SharedTimer* sharedTimer)
70 m_sharedTimer->setFiredFunction(0);
71 m_sharedTimer->stop();
72 m_pendingSharedTimerFireTime = 0;
75 m_sharedTimer = sharedTimer;
78 m_sharedTimer->setFiredFunction(ThreadTimers::sharedTimerFired);
83 void ThreadTimers::updateSharedTimer()
88 if (m_firingTimers || m_timerHeap.isEmpty()) {
89 m_pendingSharedTimerFireTime = 0;
90 m_sharedTimer->stop();
92 double nextFireTime = m_timerHeap.first()->m_nextFireTime;
93 double currentMonotonicTime = monotonicallyIncreasingTime();
94 if (m_pendingSharedTimerFireTime) {
95 // No need to restart the timer if both the pending fire time and the new fire time are in the past.
96 if (m_pendingSharedTimerFireTime <= currentMonotonicTime && nextFireTime <= currentMonotonicTime)
99 m_pendingSharedTimerFireTime = nextFireTime;
100 m_sharedTimer->setFireInterval(max(nextFireTime - currentMonotonicTime, 0.0));
104 void ThreadTimers::sharedTimerFired()
106 TRACE_EVENT_SET_SAMPLING_STATE("blink", "BlinkInternal");
108 // Redirect to non-static method.
109 PlatformThreadData::current().threadTimers().sharedTimerFiredInternal();
111 TRACE_EVENT_SET_SAMPLING_STATE("blink", "Sleeping");
114 void ThreadTimers::sharedTimerFiredInternal()
116 // Do a re-entrancy check.
119 m_firingTimers = true;
120 m_pendingSharedTimerFireTime = 0;
122 double fireTime = monotonicallyIncreasingTime();
123 double timeToQuit = fireTime + maxDurationOfFiringTimers;
125 while (!m_timerHeap.isEmpty() && m_timerHeap.first()->m_nextFireTime <= fireTime) {
126 TimerBase& timer = *m_timerHeap.first();
127 timer.m_nextFireTime = 0;
128 timer.m_unalignedNextFireTime = 0;
129 timer.heapDeleteMin();
131 double interval = timer.repeatInterval();
132 timer.setNextFireTime(interval ? fireTime + interval : 0);
134 TRACE_EVENT2("blink", "ThreadTimers::sharedTimerFiredInternal",
135 "src_file", timer.location().fileName(),
136 "src_func", timer.location().functionName());
138 // Once the timer has been fired, it may be deleted, so do nothing else with it after this point.
141 // Catch the case where the timer asked timers to fire in a nested event loop, or we are over time limit.
142 if (!m_firingTimers || timeToQuit < monotonicallyIncreasingTime() || (isMainThread() && Scheduler::shared()->shouldYieldForHighPriorityWork()))
146 m_firingTimers = false;
151 void ThreadTimers::fireTimersInNestedEventLoop()
153 // Reset the reentrancy guard so the timers can fire again.
154 m_firingTimers = false;