Quelle VsyncDispatcher.h Sprache: C

/* -*- 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 is called when a vsync occurs.
  // 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 void NotifyVsync(const VsyncEvent& aVsync) = 0;

protected:
  VsyncObserver() = default;
  virtual ~VsyncObserver() = default;
};  // VsyncObserver

class VsyncDispatcher;

// 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 : public VsyncObserver {
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorVsyncDispatcher, override)

public:
  explicit CompositorVsyncDispatcher(RefPtr<VsyncDispatcher> aVsyncDispatcher);

  // Called on the vsync thread when a hardware vsync occurs
  void NotifyVsync(const VsyncEvent& aVsync) override;

  // 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<VsyncDispatcher> mVsyncDispatcher;
  Mutex mCompositorObserverLock MOZ_UNANNOTATED;
  RefPtr<VsyncObserver> mCompositorVsyncObserver;
  bool mDidShutdown;
};

// Dispatch vsync events to various observers. This is used by:
//  - CompositorVsyncDispatcher
//  - Parent process refresh driver timers
//  - IPC for content process refresh driver timers (VsyncParent <->
//  VsyncMainChild)
//  - IPC for content process worker requestAnimationFrame (VsyncParent <->
//  VsyncWorkerChild)
//
// This class is only used in the parent process.
// There is one global vsync dispatcher which is managed by gfxPlatform.
// On Linux Wayland, there is also one vsync source and vsync dispatcher per
// widget.
// A vsync dispatcher can swap out its underlying VsyncSource. This happens, for
// example, when the layout.frame_rate pref is modified, causing us to switch
// between hardware vsync and software vsync.
class VsyncDispatcher final {
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(VsyncDispatcher)

public:
  explicit VsyncDispatcher(gfx::VsyncSource* aVsyncSource);

  // Please check CompositorVsyncDispatcher::NotifyVsync().
  void NotifyVsync(const VsyncEvent& aVsync);

  // Swap out the underlying vsync source. Can be called on any thread.
  // aVsyncSource must be non-null.
  void SetVsyncSource(gfx::VsyncSource* aVsyncSource);

  // Always non-null.
  RefPtr<gfx::VsyncSource> GetCurrentVsyncSource();

  TimeDuration GetVsyncRate();

  // 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);

  // Add and remove an observer for vsync which can only be notified on the
  // main thread. Note that keeping an observer registered means vsync will keep
  // firing, which may impact power usage. So this is intended only for "short
  // term" vsync observers.
  // These methods must be called on the parent process main thread, and the
  // observer will likewise be notified on the parent process main thread.
  void AddMainThreadObserver(VsyncObserver* aObserver);
  void RemoveMainThreadObserver(VsyncObserver* aObserver);

private:
  virtual ~VsyncDispatcher();

  // Can be called on any thread.
  void UpdateVsyncStatus();

  // Can only be called on the main thread.
  void NotifyMainThreadObservers(VsyncEvent aEvent);

  struct State {
    explicit State(gfx::VsyncSource* aVsyncSource)
        : mCurrentVsyncSource(aVsyncSource) {}
    State(State&&) = default;
    ~State() = default;

    nsTArray<RefPtr<VsyncObserver>> mObservers;
    nsTArray<RefPtr<VsyncObserver>> mMainThreadObservers;
    VsyncId mLastVsyncIdSentToMainThread;
    VsyncId mLastMainThreadProcessedVsyncId;

    // Always non-null.
    RefPtr<gfx::VsyncSource> mCurrentVsyncSource;

    // The number of skipped vsyncs since the last non-skipped vsync.
    // Reset to zero every n vsyncs, where n is given by the pref
    // gfx.display.frame-rate-divisor.
    int32_t mVsyncSkipCounter = 0;

    bool mIsObservingVsync = false;
  };

  DataMutex<State> mState;
};

}  // namespace mozilla

#endif  // mozilla_widget_VsyncDispatcher_h

quality100%

¤ Dauer der Verarbeitung: 0.16 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.