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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "MediaTimer.h"
#include <math.h>
#include "nsComponentManagerUtils.h"
#include "nsThreadUtils.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/RefPtr.h"
#include "mozilla/SharedThreadPool.h"
namespace mozilla {
NS_IMPL_ADDREF(MediaTimer)
NS_IMPL_RELEASE_WITH_DESTROY(MediaTimer, DispatchDestroy())
MediaTimer::MediaTimer()
: mMonitor("MediaTimer Monitor")
, mTimer(do_CreateInstance("@mozilla.org/timer;1"))
, mCreationTimeStamp(TimeStamp::Now())
, mUpdateScheduled(false)
{
TIMER_LOG("MediaTimer::MediaTimer");
// Use the SharedThreadPool to create an nsIThreadPool with a maximum of one
// thread, which is equivalent to an nsIThread for our purposes.
RefPtr<SharedThreadPool> threadPool(
SharedThreadPool::Get(NS_LITERAL_CSTRING("MediaTimer"), 1));
mThread = threadPool.get();
mTimer->SetTarget(mThread);
}
void
MediaTimer::DispatchDestroy()
{
// Hold a strong reference to the thread so that it doesn't get deleted in
// Destroy(), which may run completely before the stack if Dispatch() begins
// to unwind.
nsCOMPtr<nsIEventTarget> thread = mThread;
nsresult rv = thread->Dispatch(NewNonOwningRunnableMethod(this, &MediaTimer::Destroy),
NS_DISPATCH_NORMAL);
MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
(void) rv;
}
void
MediaTimer::Destroy()
{
MOZ_ASSERT(OnMediaTimerThread());
TIMER_LOG("MediaTimer::Destroy");
// Reject any outstanding entries. There's no need to acquire the monitor
// here, because we're on the timer thread and all other references to us
// must be gone.
while (!mEntries.empty()) {
mEntries.top().mPromise->Reject(false, __func__);
mEntries.pop();
}
// Cancel the timer if necessary.
CancelTimerIfArmed();
delete this;
}
bool
MediaTimer::OnMediaTimerThread()
{
bool rv = false;
mThread->IsOnCurrentThread(&rv);
return rv;
}
RefPtr<MediaTimerPromise>
MediaTimer::WaitUntil(const TimeStamp& aTimeStamp, const char* aCallSite)
{
MonitorAutoLock mon(mMonitor);
TIMER_LOG("MediaTimer::WaitUntil %lld", RelativeMicroseconds(aTimeStamp));
Entry e(aTimeStamp, aCallSite);
RefPtr<MediaTimerPromise> p = e.mPromise.get();
mEntries.push(e);
ScheduleUpdate();
return p;
}
void
MediaTimer::ScheduleUpdate()
{
mMonitor.AssertCurrentThreadOwns();
if (mUpdateScheduled) {
return;
}
mUpdateScheduled = true;
nsresult rv = mThread->Dispatch(NewRunnableMethod(this, &MediaTimer::Update),
NS_DISPATCH_NORMAL);
MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
(void) rv;
}
void
MediaTimer::Update()
{
MonitorAutoLock mon(mMonitor);
UpdateLocked();
}
void
MediaTimer::UpdateLocked()
{
MOZ_ASSERT(OnMediaTimerThread());
mMonitor.AssertCurrentThreadOwns();
mUpdateScheduled = false;
TIMER_LOG("MediaTimer::UpdateLocked");
// Resolve all the promises whose time is up.
TimeStamp now = TimeStamp::Now();
while (!mEntries.empty() && mEntries.top().mTimeStamp <= now) {
mEntries.top().mPromise->Resolve(true, __func__);
DebugOnly<TimeStamp> poppedTimeStamp = mEntries.top().mTimeStamp;
mEntries.pop();
MOZ_ASSERT_IF(!mEntries.empty(), *&poppedTimeStamp <= mEntries.top().mTimeStamp);
}
// If we've got no more entries, cancel any pending timer and bail out.
if (mEntries.empty()) {
CancelTimerIfArmed();
return;
}
// We've got more entries - (re)arm the timer for the soonest one.
if (!TimerIsArmed() || mEntries.top().mTimeStamp < mCurrentTimerTarget) {
CancelTimerIfArmed();
ArmTimer(mEntries.top().mTimeStamp, now);
}
}
/*
* We use a callback function, rather than a callback method, to ensure that
* the nsITimer does not artifically keep the refcount of the MediaTimer above
* zero. When the MediaTimer is destroyed, it safely cancels the nsITimer so that
* we never fire against a dangling closure.
*/
/* static */ void
MediaTimer::TimerCallback(nsITimer* aTimer, void* aClosure)
{
static_cast<MediaTimer*>(aClosure)->TimerFired();
}
void
MediaTimer::TimerFired()
{
MonitorAutoLock mon(mMonitor);
MOZ_ASSERT(OnMediaTimerThread());
mCurrentTimerTarget = TimeStamp();
UpdateLocked();
}
void
MediaTimer::ArmTimer(const TimeStamp& aTarget, const TimeStamp& aNow)
{
MOZ_DIAGNOSTIC_ASSERT(!TimerIsArmed());
MOZ_DIAGNOSTIC_ASSERT(aTarget > aNow);
// XPCOM timer resolution is in milliseconds. It's important to never resolve
// a timer when mTarget might compare < now (even if very close), so round up.
unsigned long delay = std::ceil((aTarget - aNow).ToMilliseconds());
TIMER_LOG("MediaTimer::ArmTimer delay=%lu", delay);
mCurrentTimerTarget = aTarget;
nsresult rv = mTimer->InitWithNamedFuncCallback(&TimerCallback, this, delay,
nsITimer::TYPE_ONE_SHOT,
"MediaTimer::TimerCallback");
MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
(void) rv;
}
} // namespace mozilla
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