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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/. */
#if !defined(MediaTimer_h_)
#define MediaTimer_h_
#include "mozilla/Monitor.h"
#include "mozilla/MozPromise.h"
#include "mozilla/TimeStamp.h"
#include <queue>
#include "nsITimer.h"
#include "mozilla/RefPtr.h"
namespace mozilla {
extern LazyLogModule gMediaTimerLog;
#define TIMER_LOG(x, ...) \
MOZ_ASSERT(gMediaTimerLog); \
MOZ_LOG(gMediaTimerLog, LogLevel::Debug, ("[MediaTimer=%p relative_t=%lld]" x, this, \
RelativeMicroseconds(TimeStamp::Now()), ##__VA_ARGS__))
// This promise type is only exclusive because so far there isn't a reason for
// it not to be. Feel free to change that.
typedef MozPromise<bool, bool, /* IsExclusive = */ true> MediaTimerPromise;
// Timers only know how to fire at a given thread, which creates an impedence
// mismatch with code that operates with TaskQueues. This class solves
// that mismatch with a dedicated (but shared) thread and a nice MozPromise-y
// interface.
class MediaTimer
{
public:
MediaTimer();
// We use a release with a custom Destroy().
NS_IMETHOD_(MozExternalRefCountType) AddRef(void);
NS_IMETHOD_(MozExternalRefCountType) Release(void);
RefPtr<MediaTimerPromise> WaitUntil(const TimeStamp& aTimeStamp, const char* aCallSite);
private:
virtual ~MediaTimer() { MOZ_ASSERT(OnMediaTimerThread()); }
void DispatchDestroy(); // Invoked by Release on an arbitrary thread.
void Destroy(); // Runs on the timer thread.
bool OnMediaTimerThread();
void ScheduleUpdate();
void Update();
void UpdateLocked();
static void TimerCallback(nsITimer* aTimer, void* aClosure);
void TimerFired();
void ArmTimer(const TimeStamp& aTarget, const TimeStamp& aNow);
bool TimerIsArmed()
{
return !mCurrentTimerTarget.IsNull();
}
void CancelTimerIfArmed()
{
MOZ_ASSERT(OnMediaTimerThread());
if (TimerIsArmed()) {
TIMER_LOG("MediaTimer::CancelTimerIfArmed canceling timer");
mTimer->Cancel();
mCurrentTimerTarget = TimeStamp();
}
}
struct Entry
{
TimeStamp mTimeStamp;
RefPtr<MediaTimerPromise::Private> mPromise;
explicit Entry(const TimeStamp& aTimeStamp, const char* aCallSite)
: mTimeStamp(aTimeStamp)
, mPromise(new MediaTimerPromise::Private(aCallSite))
{}
// Define a < overload that reverses ordering because std::priority_queue
// provides access to the largest element, and we want the smallest
// (i.e. the soonest).
bool operator<(const Entry& aOther) const
{
return mTimeStamp > aOther.mTimeStamp;
}
};
ThreadSafeAutoRefCnt mRefCnt;
NS_DECL_OWNINGTHREAD
nsCOMPtr<nsIEventTarget> mThread;
std::priority_queue<Entry> mEntries;
Monitor mMonitor;
nsCOMPtr<nsITimer> mTimer;
TimeStamp mCurrentTimerTarget;
// Timestamps only have relative meaning, so we need a base timestamp for
// logging purposes.
TimeStamp mCreationTimeStamp;
int64_t RelativeMicroseconds(const TimeStamp& aTimeStamp)
{
return (int64_t) (aTimeStamp - mCreationTimeStamp).ToMicroseconds();
}
bool mUpdateScheduled;
};
// Class for managing delayed dispatches on target thread.
class DelayedScheduler {
public:
explicit DelayedScheduler(AbstractThread* aTargetThread)
: mTargetThread(aTargetThread), mMediaTimer(new MediaTimer())
{
MOZ_ASSERT(mTargetThread);
}
bool IsScheduled() const { return !mTarget.IsNull(); }
void Reset()
{
MOZ_ASSERT(mTargetThread->IsCurrentThreadIn(),
"Must be on target thread to disconnect");
if (IsScheduled()) {
mRequest.Disconnect();
mTarget = TimeStamp();
}
}
template <typename ResolveFunc, typename RejectFunc>
void Ensure(mozilla::TimeStamp& aTarget,
ResolveFunc&& aResolver,
RejectFunc&& aRejector)
{
MOZ_ASSERT(mTargetThread->IsCurrentThreadIn());
if (IsScheduled() && mTarget <= aTarget) {
return;
}
Reset();
mTarget = aTarget;
mRequest.Begin(mMediaTimer->WaitUntil(mTarget, __func__)->Then(
mTargetThread, __func__,
Forward<ResolveFunc>(aResolver),
Forward<RejectFunc>(aRejector)));
}
void CompleteRequest()
{
MOZ_ASSERT(mTargetThread->IsCurrentThreadIn());
mRequest.Complete();
mTarget = TimeStamp();
}
private:
RefPtr<AbstractThread> mTargetThread;
RefPtr<MediaTimer> mMediaTimer;
MozPromiseRequestHolder<mozilla::MediaTimerPromise> mRequest;
TimeStamp mTarget;
};
} // namespace mozilla
#endif
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