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#include <wtf/MainThread.h> 35 36using namespace std; 37 38namespace WebCore { 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. 43static 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 48static MainThreadSharedTimer* mainThreadSharedTimer() 49{ 50 static MainThreadSharedTimer* timer = new MainThreadSharedTimer; 51 return timer; 52} 53 54ThreadTimers::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. 65void 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 81void 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(max(nextFireTime - currentMonotonicTime, 0.0)); 99 } 100} 101 102void ThreadTimers::sharedTimerFired() 103{ 104 // Redirect to non-static method. 105 threadGlobalData().threadTimers().sharedTimerFiredInternal(); 106} 107 108void ThreadTimers::sharedTimerFiredInternal() 109{ 110 // Do a re-entrancy check. 111 if (m_firingTimers) 112 return; 113 m_firingTimers = true; 114 m_pendingSharedTimerFireTime = 0; 115 116 double fireTime = monotonicallyIncreasingTime(); 117 double timeToQuit = fireTime + maxDurationOfFiringTimers; 118 119 while (!m_timerHeap.isEmpty() && m_timerHeap.first()->m_nextFireTime <= fireTime) { 120 TimerBase* timer = m_timerHeap.first(); 121 timer->m_nextFireTime = 0; 122 timer->m_unalignedNextFireTime = 0; 123 timer->heapDeleteMin(); 124 125 double interval = timer->repeatInterval(); 126 timer->setNextFireTime(interval ? fireTime + interval : 0); 127 128 // Once the timer has been fired, it may be deleted, so do nothing else with it after this point. 129 timer->fired(); 130 131 // Catch the case where the timer asked timers to fire in a nested event loop, or we are over time limit. 132 if (!m_firingTimers || timeToQuit < monotonicallyIncreasingTime()) 133 break; 134 } 135 136 m_firingTimers = false; 137 138 updateSharedTimer(); 139} 140 141void ThreadTimers::fireTimersInNestedEventLoop() 142{ 143 // Reset the reentrancy guard so the timers can fire again. 144 m_firingTimers = false; 145 updateSharedTimer(); 146} 147 148} // namespace WebCore 149 150