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-rw-r--r--dom/media/MediaTimer.cpp192
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