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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* 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 "VsyncSource.h"
#include "nsThreadUtils.h"
#include "nsXULAppAPI.h"
#include "mozilla/VsyncDispatcher.h"
#include "MainThreadUtils.h"
#include "gfxPlatform.h"
#ifdef MOZ_WAYLAND
# include "WaylandVsyncSource.h"
#endif
namespace mozilla {
namespace gfx {
VsyncSource::VsyncSource() : mState("VsyncSource::State") {
MOZ_ASSERT(NS_IsMainThread());
}
VsyncSource::~VsyncSource() { MOZ_ASSERT(NS_IsMainThread()); }
// Called on the vsync thread
void VsyncSource::NotifyVsync(const TimeStamp& aVsyncTimestamp,
const TimeStamp& aOutputTimestamp) {
VsyncId vsyncId;
nsTArray<DispatcherRefWithCount> dispatchers;
{
auto state = mState.Lock();
vsyncId = state->mVsyncId.Next();
dispatchers = state->mDispatchers.Clone();
state->mVsyncId = vsyncId;
}
// Notify our listeners, outside of the lock.
const VsyncEvent event(vsyncId, aVsyncTimestamp, aOutputTimestamp);
for (const auto& dispatcher : dispatchers) {
dispatcher.mDispatcher->NotifyVsync(event);
}
}
void VsyncSource::AddVsyncDispatcher(VsyncDispatcher* aVsyncDispatcher) {
MOZ_ASSERT(aVsyncDispatcher);
{
auto state = mState.Lock();
// Find the dispatcher in mDispatchers. If it is already present, increment
// the count. If not, add it with a count of 1.
bool found = false;
for (auto& dispatcherRefWithCount : state->mDispatchers) {
if (dispatcherRefWithCount.mDispatcher == aVsyncDispatcher) {
dispatcherRefWithCount.mCount++;
found = true;
break;
}
}
if (!found) {
state->mDispatchers.AppendElement(
DispatcherRefWithCount{aVsyncDispatcher, 1});
}
}
UpdateVsyncStatus();
}
void VsyncSource::RemoveVsyncDispatcher(VsyncDispatcher* aVsyncDispatcher) {
MOZ_ASSERT(aVsyncDispatcher);
{
auto state = mState.Lock();
// Find the dispatcher in mDispatchers. If found, decrement the count.
// If the count becomes zero, remove it from mDispatchers.
for (auto it = state->mDispatchers.begin(); it != state->mDispatchers.end();
++it) {
if (it->mDispatcher == aVsyncDispatcher) {
it->mCount--;
if (it->mCount == 0) {
state->mDispatchers.RemoveElementAt(it);
}
break;
}
}
// In the future we should probably MOZ_RELEASE_ASSERT here that we don't
// try to remove a dispatcher which isn't in mDispatchers.
}
UpdateVsyncStatus();
}
// This is the base class implementation. Subclasses override this method.
TimeDuration VsyncSource::GetVsyncRate() {
// If hardware queries fail / are unsupported, we have to just guess.
return TimeDuration::FromMilliseconds(1000.0 / 60.0);
}
void VsyncSource::UpdateVsyncStatus() {
if (!NS_IsMainThread()) {
NS_DispatchToMainThread(NS_NewRunnableFunction(
"VsyncSource::UpdateVsyncStatus",
[self = RefPtr{this}] { self->UpdateVsyncStatus(); }));
return;
}
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
auto state = mState.Lock();
enableVsync = !state->mDispatchers.IsEmpty();
}
if (enableVsync) {
EnableVsync();
} else {
DisableVsync();
}
if (IsVsyncEnabled() != enableVsync) {
NS_WARNING("Vsync status did not change.");
}
}
// static
Maybe<TimeDuration> VsyncSource::GetFastestVsyncRate() {
Maybe<TimeDuration> retVal;
if (!gfxPlatform::Initialized()) {
return retVal;
}
RefPtr<VsyncDispatcher> vsyncDispatcher =
gfxPlatform::GetPlatform()->GetGlobalVsyncDispatcher();
RefPtr<VsyncSource> vsyncSource = vsyncDispatcher->GetCurrentVsyncSource();
if (vsyncSource->IsVsyncEnabled()) {
retVal.emplace(vsyncSource->GetVsyncRate());
#ifdef MOZ_WAYLAND
Maybe<TimeDuration> waylandRate = WaylandVsyncSource::GetFastestVsyncRate();
if (waylandRate) {
if (!retVal) {
retVal.emplace(*waylandRate);
} else if (*waylandRate < *retVal) {
retVal = waylandRate;
}
}
#endif
}
return retVal;
}
} // namespace gfx
} // namespace mozilla
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