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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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 "mozilla/DebugOnly.h"
#include "mozilla/RefPtr.h"
#include "mozilla/SharedThreadPool.h"
#include "mozilla/Unused.h"
#include "nsComponentManagerUtils.h"
#include "nsThreadUtils.h"
#include <math.h>
namespace mozilla {
MediaTimer::MediaTimer(bool aFuzzy)
: mMonitor("MediaTimer Monitor"),
mCreationTimeStamp(TimeStamp::Now()),
mUpdateScheduled(false),
mFuzzy(aFuzzy) {
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("MediaTimer"_ns, 1));
mThread = threadPool.get();
mTimer = NS_NewTimer(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("MediaTimer::Destroy", this,
&MediaTimer::Destroy),
NS_DISPATCH_NORMAL);
MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
Unused << rv;
(void)rv;
}
void MediaTimer::Destroy() {
MOZ_ASSERT(OnMediaTimerThread());
TIMER_LOG("MediaTimer::Destroy");
// Reject any outstanding entries.
{
MonitorAutoLock lock(mMonitor);
Reject();
}
// Cancel the timer if necessary.
CancelTimerIfArmed();
delete this;
}
bool MediaTimer::OnMediaTimerThread() {
bool rv = false;
mThread->IsOnCurrentThread(&rv);
return rv;
}
RefPtr<MediaTimerPromise> MediaTimer::WaitFor(const TimeDuration& aDuration,
const char* aCallSite) {
return WaitUntil(TimeStamp::Now() + aDuration, aCallSite);
}
RefPtr<MediaTimerPromise> MediaTimer::WaitUntil(const TimeStamp& aTimeStamp,
const char* aCallSite) {
MonitorAutoLock mon(mMonitor);
TIMER_LOG("MediaTimer::WaitUntil %" PRId64, RelativeMicroseconds(aTimeStamp));
Entry e(aTimeStamp, aCallSite);
RefPtr<MediaTimerPromise> p = e.mPromise.get();
mEntries.push(e);
ScheduleUpdate();
return p;
}
void MediaTimer::Cancel() {
MonitorAutoLock mon(mMonitor);
TIMER_LOG("MediaTimer::Cancel");
Reject();
}
void MediaTimer::ScheduleUpdate() {
mMonitor.AssertCurrentThreadOwns();
if (mUpdateScheduled) {
return;
}
mUpdateScheduled = true;
nsresult rv = mThread->Dispatch(
NewRunnableMethod("MediaTimer::Update", this, &MediaTimer::Update),
NS_DISPATCH_NORMAL);
MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
Unused << rv;
(void)rv;
}
void MediaTimer::Update() {
MonitorAutoLock mon(mMonitor);
UpdateLocked();
}
bool MediaTimer::IsExpired(const TimeStamp& aTarget, const TimeStamp& aNow) {
MOZ_ASSERT(OnMediaTimerThread());
mMonitor.AssertCurrentThreadOwns();
// Treat this timer as expired in fuzzy mode even if it is fired
// slightly (< 1ms) before the schedule target. So we don't need to schedule a
// timer with very small timeout again when the client doesn't need a high-res
// timer.
TimeStamp t = mFuzzy ? aTarget - TimeDuration::FromMilliseconds(1) : aTarget;
return t <= aNow;
}
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() && IsExpired(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);
}
}
void MediaTimer::Reject() {
mMonitor.AssertCurrentThreadOwns();
while (!mEntries.empty()) {
mEntries.top().mPromise->Reject(false, __func__);
mEntries.pop();
}
}
/*
* 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));
Unused << rv;
(void)rv;
}
} // namespace mozilla