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/*
* Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
* Copyright (C) 2009 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "ThreadTimers.h"
#include "SharedTimer.h"
#include "ThreadGlobalData.h"
#include "Timer.h"
#include <wtf/CurrentTime.h>
#include <wtf/MainThread.h>
using namespace std;
namespace WebCore {
// Fire timers for this length of time, and then quit to let the run loop process user input events.
// 100ms is about a perceptable delay in UI, so use a half of that as a threshold.
// This is to prevent UI freeze when there are too many timers or machine performance is low.
static const double maxDurationOfFiringTimers = 0.050;
// Timers are created, started and fired on the same thread, and each thread has its own ThreadTimers
// copy to keep the heap and a set of currently firing timers.
static MainThreadSharedTimer* mainThreadSharedTimer()
{
static MainThreadSharedTimer* timer = new MainThreadSharedTimer;
return timer;
}
ThreadTimers::ThreadTimers()
: m_sharedTimer(0)
, m_firingTimers(false)
, m_pendingSharedTimerFireTime(0)
{
if (isMainThread())
setSharedTimer(mainThreadSharedTimer());
}
// A worker thread may initialize SharedTimer after some timers are created.
// Also, SharedTimer can be replaced with 0 before all timers are destroyed.
void ThreadTimers::setSharedTimer(SharedTimer* sharedTimer)
{
if (m_sharedTimer) {
m_sharedTimer->setFiredFunction(0);
m_sharedTimer->stop();
m_pendingSharedTimerFireTime = 0;
}
m_sharedTimer = sharedTimer;
if (sharedTimer) {
m_sharedTimer->setFiredFunction(ThreadTimers::sharedTimerFired);
updateSharedTimer();
}
}
void ThreadTimers::updateSharedTimer()
{
if (!m_sharedTimer)
return;
if (m_firingTimers || m_timerHeap.isEmpty()) {
m_pendingSharedTimerFireTime = 0;
m_sharedTimer->stop();
} else {
double nextFireTime = m_timerHeap.first()->m_nextFireTime;
double currentMonotonicTime = monotonicallyIncreasingTime();
if (m_pendingSharedTimerFireTime) {
// No need to restart the timer if both the pending fire time and the new fire time are in the past.
if (m_pendingSharedTimerFireTime <= currentMonotonicTime && nextFireTime <= currentMonotonicTime)
return;
}
m_pendingSharedTimerFireTime = nextFireTime;
m_sharedTimer->setFireInterval(max(nextFireTime - currentMonotonicTime, 0.0));
}
}
void ThreadTimers::sharedTimerFired()
{
// Redirect to non-static method.
threadGlobalData().threadTimers().sharedTimerFiredInternal();
}
void ThreadTimers::sharedTimerFiredInternal()
{
// Do a re-entrancy check.
if (m_firingTimers)
return;
m_firingTimers = true;
m_pendingSharedTimerFireTime = 0;
double fireTime = monotonicallyIncreasingTime();
double timeToQuit = fireTime + maxDurationOfFiringTimers;
while (!m_timerHeap.isEmpty() && m_timerHeap.first()->m_nextFireTime <= fireTime) {
TimerBase* timer = m_timerHeap.first();
timer->m_nextFireTime = 0;
timer->m_unalignedNextFireTime = 0;
timer->heapDeleteMin();
double interval = timer->repeatInterval();
timer->setNextFireTime(interval ? fireTime + interval : 0);
// Once the timer has been fired, it may be deleted, so do nothing else with it after this point.
timer->fired();
// Catch the case where the timer asked timers to fire in a nested event loop, or we are over time limit.
if (!m_firingTimers || timeToQuit < monotonicallyIncreasingTime())
break;
}
m_firingTimers = false;
updateSharedTimer();
}
void ThreadTimers::fireTimersInNestedEventLoop()
{
// Reset the reentrancy guard so the timers can fire again.
m_firingTimers = false;
updateSharedTimer();
}
} // namespace WebCore
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