gecko-dev/widget/VsyncDispatcher.h

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/* -*- Mode: C++; tab-width: 2; 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/. */
#ifndef mozilla_widget_VsyncDispatcher_h
#define mozilla_widget_VsyncDispatcher_h
#include "mozilla/DataMutex.h"
#include "mozilla/TimeStamp.h"
#include "nsISupportsImpl.h"
#include "nsTArray.h"
#include "mozilla/RefPtr.h"
#include "VsyncSource.h"
namespace mozilla {
class VsyncObserver {
NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
public:
// The method called when a vsync occurs. Return true if some work was done.
// In general, this vsync notification will occur on the hardware vsync
// thread from VsyncSource. But it might also be called on PVsync ipc thread
// if this notification is cross process. Thus all observer should check the
// thread model before handling the real task.
virtual bool NotifyVsync(const VsyncEvent& aVsync) = 0;
protected:
VsyncObserver() = default;
virtual ~VsyncObserver() = default;
}; // VsyncObserver
// Used to dispatch vsync events in the parent process to compositors.
//
// When the compositor is in-process, CompositorWidgets own a
// CompositorVsyncDispatcher, and directly attach the compositor's observer
// to it.
//
// When the compositor is out-of-process, the CompositorWidgetDelegate owns
// the vsync dispatcher instead. The widget receives vsync observer/unobserve
// commands via IPDL, and uses this to attach a CompositorWidgetVsyncObserver.
// This observer forwards vsync notifications (on the vsync thread) to a
// dedicated vsync I/O thread, which then forwards the notification to the
// compositor thread in the compositor process.
class CompositorVsyncDispatcher final {
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorVsyncDispatcher)
public:
CompositorVsyncDispatcher();
explicit CompositorVsyncDispatcher(RefPtr<gfx::VsyncSource> aVsyncSource);
// Called on the vsync thread when a hardware vsync occurs
void NotifyVsync(const VsyncEvent& aVsync);
void MoveToSource(const RefPtr<gfx::VsyncSource>& aVsyncSource);
// Compositor vsync observers must be added/removed on the compositor thread
void SetCompositorVsyncObserver(VsyncObserver* aVsyncObserver);
void Shutdown();
private:
virtual ~CompositorVsyncDispatcher();
void ObserveVsync(bool aEnable);
RefPtr<gfx::VsyncSource> mVsyncSource;
Mutex mCompositorObserverLock MOZ_UNANNOTATED;
RefPtr<VsyncObserver> mCompositorVsyncObserver;
bool mDidShutdown;
};
// Dispatch vsync events to various observers. This is used by:
// - Parent process refresh driver timers
// - IPC for content process refresh driver timers (VsyncParent <->
// VsyncMainChild)
// - IPC for content process worker requestAnimationFrame (VsyncParent <->
// VsyncWorkerChild)
class RefreshTimerVsyncDispatcher final {
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(RefreshTimerVsyncDispatcher)
public:
explicit RefreshTimerVsyncDispatcher(gfx::VsyncSource* aVsyncSource);
// Please check CompositorVsyncDispatcher::NotifyVsync().
void NotifyVsync(const VsyncEvent& aVsync);
void MoveToSource(gfx::VsyncSource* aVsyncSource);
// Add a vsync observer to this dispatcher. This is a no-op if the observer is
// already registered. Can be called from any thread.
void AddVsyncObserver(VsyncObserver* aVsyncObserver);
// Remove a vsync observer from this dispatcher. This is a no-op if the
// observer is not registered. Can be called from any thread.
void RemoveVsyncObserver(VsyncObserver* aVsyncObserver);
private:
virtual ~RefreshTimerVsyncDispatcher();
void UpdateVsyncStatus();
bool NeedsVsync();
// We need to hold a weak ref to the vsync source we belong to in order to
// notify it of our vsync requirement. The vsync source holds a RefPtr to us,
// so we can't hold a RefPtr back without causing a cyclic dependency.
gfx::VsyncSource* mVsyncSource;
DataMutex<nsTArray<RefPtr<VsyncObserver>>> mVsyncObservers;
};
} // namespace mozilla
#endif // mozilla_widget_VsyncDispatcher_h