nsresult TimerThread::TimerDelayChanged(nsTimerImpl *aTimer)
{
nsAutoLock lock(mLock);
// Our caller has a strong ref to aTimer, so it can't go away here under
// ReleaseTimerInternal.
RemoveTimerInternal(aTimer);
PRInt32 i = AddTimerInternal(aTimer);
if (i < 0)
return NS_ERROR_OUT_OF_MEMORY;
// Awaken the timer thread.
if (mCondVar && mWaiting && i == 0)
PR_NotifyCondVar(mCondVar);
return NS_OK;
}
nsresult TimerThread::RemoveTimer(nsTimerImpl *aTimer)
{
nsAutoLock lock(mLock);
// Remove the timer from our array. Tell callers that aTimer was not found
// by returning NS_ERROR_NOT_AVAILABLE. Unlike the TimerDelayChanged case
// immediately above, our caller may be passing a (now-)weak ref in via the
// aTimer param, specifically when nsTimerImpl::Release loses a race with
// TimerThread::Run, must wait for the mLock auto-lock here, and during the
// wait Run drops the only remaining ref to aTimer via RemoveTimerInternal.
if (!RemoveTimerInternal(aTimer))
return NS_ERROR_NOT_AVAILABLE;
// Awaken the timer thread.
if (mCondVar && mWaiting)
PR_NotifyCondVar(mCondVar);
return NS_OK;
}
/* void Run(); */
NS_IMETHODIMP TimerThread::Run()
{
nsAutoLock lock(mLock);
while (!mShutdown) {
PRIntervalTime waitFor;
if (mSleeping) {
// Sleep for 0.1 seconds while not firing timers.
waitFor = PR_MillisecondsToInterval(100);
} else {
waitFor = PR_INTERVAL_NO_TIMEOUT;
PRIntervalTime now = PR_IntervalNow();
nsTimerImpl *timer = nsnull;
if (mTimers.Count() > 0) {
timer = static_cast<nsTimerImpl*>(mTimers[0]);
if (!TIMER_LESS_THAN(now, timer->mTimeout + mTimeoutAdjustment)) {
next:
// NB: AddRef before the Release under RemoveTimerInternal to avoid
// mRefCnt passing through zero, in case all other refs than the one
// from mTimers have gone away (the last non-mTimers[i]-ref's Release
// must be racing with us, blocked in gThread->RemoveTimer waiting
// for TimerThread::mLock, under nsTimerImpl::Release.
NS_ADDREF(timer);
RemoveTimerInternal(timer);
// We release mLock around the Fire call to avoid deadlock.
lock.unlock();
#ifdef DEBUG_TIMERS
if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
PR_LOG(gTimerLog, PR_LOG_DEBUG,
("Timer thread woke up %dms from when it was supposed to\n",
(now >= timer->mTimeout)
? PR_IntervalToMilliseconds(now - timer->mTimeout)
: -(PRInt32)PR_IntervalToMilliseconds(timer->mTimeout-now))
);
}
#endif
// We are going to let the call to PostTimerEvent here handle the
// release of the timer so that we don't end up releasing the timer
// on the TimerThread instead of on the thread it targets.
if (NS_FAILED(timer->PostTimerEvent())) {
nsrefcnt rc;
NS_RELEASE2(timer, rc);
// The nsITimer interface requires that its users keep a reference
// to the timers they use while those timers are initialized but
// have not yet fired. If this ever happens, it is a bug in the
// code that created and used the timer.
//
// Further, note that this should never happen even with a
// misbehaving user, because nsTimerImpl::Release checks for a
// refcount of 1 with an armed timer (a timer whose only reference
// is from the timer thread) and when it hits this will remove the
// timer from the timer thread and thus destroy the last reference,
// preventing this situation from occurring.
NS_ASSERTION(rc != 0, "destroyed timer off its target thread!");
}
timer = nsnull;
lock.lock();
if (mShutdown)
break;
// Update now, as PostTimerEvent plus the locking may have taken a
// tick or two, and we may goto next below.
now = PR_IntervalNow();
}
}
if (mTimers.Count() > 0) {
timer = static_cast<nsTimerImpl *>(mTimers[0]);
PRIntervalTime timeout = timer->mTimeout + mTimeoutAdjustment;
// Don't wait at all (even for PR_INTERVAL_NO_WAIT) if the next timer
// is due now or overdue.
if (!TIMER_LESS_THAN(now, timeout))
goto next;
waitFor = timeout - now;
}
#ifdef DEBUG_TIMERS
if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
if (waitFor == PR_INTERVAL_NO_TIMEOUT)
PR_LOG(gTimerLog, PR_LOG_DEBUG,
("waiting for PR_INTERVAL_NO_TIMEOUT\n"));
else
PR_LOG(gTimerLog, PR_LOG_DEBUG,
("waiting for %u\n", PR_IntervalToMilliseconds(waitFor)));
}
#endif
}
mWaiting = PR_TRUE;
PR_WaitCondVar(mCondVar, waitFor);
mWaiting = PR_FALSE;
}
return NS_OK;
}
/* void Run(); */
NS_IMETHODIMP TimerThread::Run()
{
nsAutoLock lock(mLock);
// We need to know how many microseconds give a positive PRIntervalTime. This
// is platform-dependent, we calculate it at runtime now.
// First we find a value such that PR_MicrosecondsToInterval(high) = 1
PRInt32 low = 0, high = 1;
while (PR_MicrosecondsToInterval(high) == 0)
high <<= 1;
// We now have
// PR_MicrosecondsToInterval(low) = 0
// PR_MicrosecondsToInterval(high) = 1
// and we can proceed to find the critical value using binary search
while (high-low > 1) {
PRInt32 mid = (high+low) >> 1;
if (PR_MicrosecondsToInterval(mid) == 0)
low = mid;
else
high = mid;
}
// Half of the amount of microseconds needed to get positive PRIntervalTime.
// We use this to decide how to round our wait times later
PRInt32 halfMicrosecondsIntervalResolution = high >> 1;
while (!mShutdown) {
// Have to use PRIntervalTime here, since PR_WaitCondVar takes it
PRIntervalTime waitFor;
if (mSleeping) {
// Sleep for 0.1 seconds while not firing timers.
waitFor = PR_MillisecondsToInterval(100);
} else {
waitFor = PR_INTERVAL_NO_TIMEOUT;
TimeStamp now = TimeStamp::Now();
nsTimerImpl *timer = nsnull;
if (!mTimers.IsEmpty()) {
timer = mTimers[0];
if (now >= timer->mTimeout + mTimeoutAdjustment) {
next:
// NB: AddRef before the Release under RemoveTimerInternal to avoid
// mRefCnt passing through zero, in case all other refs than the one
// from mTimers have gone away (the last non-mTimers[i]-ref's Release
// must be racing with us, blocked in gThread->RemoveTimer waiting
// for TimerThread::mLock, under nsTimerImpl::Release.
NS_ADDREF(timer);
RemoveTimerInternal(timer);
// We release mLock around the Fire call to avoid deadlock.
lock.unlock();
#ifdef DEBUG_TIMERS
if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
PR_LOG(gTimerLog, PR_LOG_DEBUG,
("Timer thread woke up %fms from when it was supposed to\n",
fabs((now - timer->mTimeout).ToMilliseconds())));
}
#endif
// We are going to let the call to PostTimerEvent here handle the
// release of the timer so that we don't end up releasing the timer
// on the TimerThread instead of on the thread it targets.
if (NS_FAILED(timer->PostTimerEvent())) {
nsrefcnt rc;
NS_RELEASE2(timer, rc);
// The nsITimer interface requires that its users keep a reference
// to the timers they use while those timers are initialized but
// have not yet fired. If this ever happens, it is a bug in the
// code that created and used the timer.
//
// Further, note that this should never happen even with a
// misbehaving user, because nsTimerImpl::Release checks for a
// refcount of 1 with an armed timer (a timer whose only reference
// is from the timer thread) and when it hits this will remove the
// timer from the timer thread and thus destroy the last reference,
// preventing this situation from occurring.
NS_ASSERTION(rc != 0, "destroyed timer off its target thread!");
}
timer = nsnull;
lock.lock();
if (mShutdown)
break;
// Update now, as PostTimerEvent plus the locking may have taken a
// tick or two, and we may goto next below.
now = TimeStamp::Now();
}
}
if (!mTimers.IsEmpty()) {
timer = mTimers[0];
TimeStamp timeout = timer->mTimeout + mTimeoutAdjustment;
// Don't wait at all (even for PR_INTERVAL_NO_WAIT) if the next timer
// is due now or overdue.
//
// Note that we can only sleep for integer values of a certain
// resolution. We use halfMicrosecondsIntervalResolution, calculated
// before, to do the optimal rounding (i.e., of how to decide what
// interval is so small we should not wait at all).
double microseconds = (timeout - now).ToMilliseconds()*1000;
if (microseconds < halfMicrosecondsIntervalResolution)
goto next; // round down; execute event now
waitFor = PR_MicrosecondsToInterval(microseconds);
if (waitFor == 0)
waitFor = 1; // round up, wait the minimum time we can wait
}
#ifdef DEBUG_TIMERS
if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
if (waitFor == PR_INTERVAL_NO_TIMEOUT)
PR_LOG(gTimerLog, PR_LOG_DEBUG,
("waiting for PR_INTERVAL_NO_TIMEOUT\n"));
else
PR_LOG(gTimerLog, PR_LOG_DEBUG,
("waiting for %u\n", PR_IntervalToMilliseconds(waitFor)));
}
#endif
}
mWaiting = PR_TRUE;
PR_WaitCondVar(mCondVar, waitFor);
mWaiting = PR_FALSE;
}
return NS_OK;
}
