diff options
Diffstat (limited to '')
| -rw-r--r-- | dom/media/MediaTimer.cpp | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/dom/media/MediaTimer.cpp b/dom/media/MediaTimer.cpp new file mode 100644 index 0000000000..c34eb816fa --- /dev/null +++ b/dom/media/MediaTimer.cpp @@ -0,0 +1,192 @@ +/* -*- 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); + + const TimeDuration delay = aTarget - aNow; + TIMER_LOG("MediaTimer::ArmTimer delay=%.3fms", delay.ToMilliseconds()); + mCurrentTimerTarget = aTarget; + MOZ_ALWAYS_SUCCEEDS(mTimer->InitHighResolutionWithNamedFuncCallback( + &TimerCallback, this, delay, nsITimer::TYPE_ONE_SHOT, + "MediaTimer::TimerCallback")); +} + +} // namespace mozilla |