mirror of
https://github.com/mozilla/gecko-dev.git
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142 lines
3.7 KiB
C++
142 lines
3.7 KiB
C++
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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#include "SoftwareVsyncSource.h"
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#include "base/task.h"
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#include "nsThreadUtils.h"
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SoftwareVsyncSource::SoftwareVsyncSource()
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{
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MOZ_ASSERT(NS_IsMainThread());
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mGlobalDisplay = new SoftwareDisplay();
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}
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SoftwareVsyncSource::~SoftwareVsyncSource()
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{
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MOZ_ASSERT(NS_IsMainThread());
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// Ensure we disable vsync on the main thread here
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mGlobalDisplay->DisableVsync();
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mGlobalDisplay = nullptr;
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}
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SoftwareDisplay::SoftwareDisplay()
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: mVsyncEnabled(false)
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, mCurrentTaskMonitor("SoftwareVsyncCurrentTaskMonitor")
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{
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// Mimic 60 fps
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MOZ_ASSERT(NS_IsMainThread());
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const double rate = 1000 / 60.0;
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mVsyncRate = mozilla::TimeDuration::FromMilliseconds(rate);
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mVsyncThread = new base::Thread("SoftwareVsyncThread");
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MOZ_RELEASE_ASSERT(mVsyncThread->Start(), "Could not start software vsync thread");
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}
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void
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SoftwareDisplay::EnableVsync()
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{
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MOZ_ASSERT(NS_IsMainThread());
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if (IsVsyncEnabled()) {
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return;
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}
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{ // scope lock
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mozilla::MonitorAutoLock lock(mCurrentTaskMonitor);
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mVsyncEnabled = true;
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MOZ_ASSERT(mVsyncThread->IsRunning());
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mCurrentVsyncTask = NewRunnableMethod(this,
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&SoftwareDisplay::NotifyVsync,
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mozilla::TimeStamp::Now());
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mVsyncThread->message_loop()->PostTask(FROM_HERE, mCurrentVsyncTask);
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}
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}
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void
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SoftwareDisplay::DisableVsync()
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{
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MOZ_ASSERT(NS_IsMainThread());
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if (!IsVsyncEnabled()) {
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return;
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}
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MOZ_ASSERT(mVsyncThread->IsRunning());
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{ // scope lock
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mozilla::MonitorAutoLock lock(mCurrentTaskMonitor);
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mVsyncEnabled = false;
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if (mCurrentVsyncTask) {
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mCurrentVsyncTask->Cancel();
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mCurrentVsyncTask = nullptr;
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}
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}
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}
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bool
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SoftwareDisplay::IsVsyncEnabled()
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{
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MOZ_ASSERT(NS_IsMainThread());
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mozilla::MonitorAutoLock lock(mCurrentTaskMonitor);
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return mVsyncEnabled;
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}
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bool
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SoftwareDisplay::IsInSoftwareVsyncThread()
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{
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return mVsyncThread->thread_id() == PlatformThread::CurrentId();
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}
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void
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SoftwareDisplay::NotifyVsync(mozilla::TimeStamp aVsyncTimestamp)
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{
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MOZ_ASSERT(IsInSoftwareVsyncThread());
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mozilla::TimeStamp displayVsyncTime = aVsyncTimestamp;
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mozilla::TimeStamp now = mozilla::TimeStamp::Now();
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// Posted tasks can only have integer millisecond delays
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// whereas TimeDurations can have floating point delays.
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// Thus the vsync timestamp can be in the future, which large parts
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// of the system can't handle, including animations. Force the timestamp to be now.
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if (aVsyncTimestamp > now) {
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displayVsyncTime = now;
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}
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Display::NotifyVsync(displayVsyncTime);
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// Prevent skew by still scheduling based on the original
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// vsync timestamp
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ScheduleNextVsync(aVsyncTimestamp);
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}
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void
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SoftwareDisplay::ScheduleNextVsync(mozilla::TimeStamp aVsyncTimestamp)
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{
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MOZ_ASSERT(IsInSoftwareVsyncThread());
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mozilla::TimeStamp nextVsync = aVsyncTimestamp + mVsyncRate;
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mozilla::TimeDuration delay = nextVsync - mozilla::TimeStamp::Now();
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if (delay.ToMilliseconds() < 0) {
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delay = mozilla::TimeDuration::FromMilliseconds(0);
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}
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mozilla::MonitorAutoLock lock(mCurrentTaskMonitor);
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// We could've disabled vsync between this posted task and when it actually
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// executes
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if (!mVsyncEnabled) {
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return;
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}
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mCurrentVsyncTask = NewRunnableMethod(this,
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&SoftwareDisplay::NotifyVsync,
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nextVsync);
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mVsyncThread->message_loop()->PostDelayedTask(FROM_HERE,
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mCurrentVsyncTask,
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delay.ToMilliseconds());
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}
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SoftwareDisplay::~SoftwareDisplay()
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{
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MOZ_ASSERT(NS_IsMainThread());
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mVsyncThread->Stop();
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delete mVsyncThread;
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}
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