void
VsyncSource::Display::UpdateVsyncStatus()
{
MOZ_ASSERT(NS_IsMainThread());
// WARNING: This function SHOULD NOT BE CALLED WHILE HOLDING LOCKS
// NotifyVsync grabs a lock to dispatch vsync events
// When disabling vsync, we wait for the underlying thread to stop on some platforms
// We can deadlock if we wait for the underlying vsync thread to stop
// while the vsync thread is in NotifyVsync.
bool enableVsync = false;
{ // scope lock
MutexAutoLock lock(mDispatcherLock);
enableVsync = !mCompositorVsyncDispatchers.IsEmpty() || mRefreshTimerNeedsVsync;
}
if (enableVsync) {
EnableVsync();
} else {
DisableVsync();
}
if (IsVsyncEnabled() != enableVsync) {
NS_WARNING("Vsync status did not change.");
}
}
void
SoftwareDisplay::DisableVsync()
{
MOZ_ASSERT(NS_IsMainThread());
if (!IsVsyncEnabled()) {
return;
}
MOZ_ASSERT(mVsyncThread->IsRunning());
{ // scope lock
mozilla::MonitorAutoLock lock(mCurrentTaskMonitor);
mVsyncEnabled = false;
if (mCurrentVsyncTask) {
mCurrentVsyncTask->Cancel();
mCurrentVsyncTask = nullptr;
}
}
mVsyncThread->Stop();
}
void
SoftwareDisplay::EnableVsync()
{
MOZ_ASSERT(NS_IsMainThread());
if (IsVsyncEnabled()) {
return;
}
{ // scope lock
mozilla::MonitorAutoLock lock(mCurrentTaskMonitor);
mVsyncEnabled = true;
MOZ_ASSERT(!mVsyncThread->IsRunning());
MOZ_RELEASE_ASSERT(mVsyncThread->Start(), "Could not start software vsync thread");
mCurrentVsyncTask = NewRunnableMethod(this,
&SoftwareDisplay::NotifyVsync,
mozilla::TimeStamp::Now());
mVsyncThread->message_loop()->PostTask(FROM_HERE, mCurrentVsyncTask);
}
}