widget/VsyncDispatcher.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   4  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef mozilla_widget_VsyncDispatcher_h
   7 #define mozilla_widget_VsyncDispatcher_h
   8
   9 #include "mozilla/Mutex.h"
  10 #include "mozilla/TimeStamp.h"
  11 #include "nsISupportsImpl.h"
  12 #include "nsTArray.h"
  13 #include "mozilla/RefPtr.h"
  14 #include "VsyncSource.h"
  15
  16 namespace mozilla {
  17
  18 class VsyncObserver {
  19   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(VsyncObserver)
  20
  21  public:
  22   // The method called when a vsync occurs. Return true if some work was done.
  23   // In general, this vsync notification will occur on the hardware vsync
  24   // thread from VsyncSource. But it might also be called on PVsync ipc thread
  25   // if this notification is cross process. Thus all observer should check the
  26   // thread model before handling the real task.
  27   virtual bool NotifyVsync(const VsyncEvent& aVsync) = 0;
  28
  29  protected:
  30   VsyncObserver() {}
  31   virtual ~VsyncObserver() {}
  32 };  // VsyncObserver
  33
  34 // Used to dispatch vsync events in the parent process to compositors.
  35 //
  36 // When the compositor is in-process, CompositorWidgets own a
  37 // CompositorVsyncDispatcher, and directly attach the compositor's observer
  38 // to it.
  39 //
  40 // When the compositor is out-of-process, the CompositorWidgetDelegate owns
  41 // the vsync dispatcher instead. The widget receives vsync observer/unobserve
  42 // commands via IPDL, and uses this to attach a CompositorWidgetVsyncObserver.
  43 // This observer forwards vsync notifications (on the vsync thread) to a
  44 // dedicated vsync I/O thread, which then forwards the notification to the
  45 // compositor thread in the compositor process.
  46 class CompositorVsyncDispatcher final {
  47   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorVsyncDispatcher)
  48
  49  public:
  50   CompositorVsyncDispatcher();
  51
  52   // Called on the vsync thread when a hardware vsync occurs
  53   void NotifyVsync(const VsyncEvent& aVsync);
  54
  55   // Compositor vsync observers must be added/removed on the compositor thread
  56   void SetCompositorVsyncObserver(VsyncObserver* aVsyncObserver);
  57   void Shutdown();
  58
  59  private:
  60   virtual ~CompositorVsyncDispatcher();
  61   void ObserveVsync(bool aEnable);
  62
  63   Mutex mCompositorObserverLock;
  64   RefPtr<VsyncObserver> mCompositorVsyncObserver;
  65   bool mDidShutdown;
  66 };
  67
  68 // Dispatch vsync event to ipc actor parent and chrome RefreshTimer.
  69 class RefreshTimerVsyncDispatcher final {
  70   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(RefreshTimerVsyncDispatcher)
  71
  72  public:
  73   RefreshTimerVsyncDispatcher();
  74
  75   // Please check CompositorVsyncDispatcher::NotifyVsync().
  76   void NotifyVsync(const VsyncEvent& aVsync);
  77
  78   // Set chrome process's RefreshTimer to this dispatcher.
  79   // This function can be called from any thread.
  80   void SetParentRefreshTimer(VsyncObserver* aVsyncObserver);
  81
  82   // Add or remove the content process' RefreshTimer to this dispatcher. This
  83   // will be a no-op for AddChildRefreshTimer() if the observer is already
  84   // registered.
  85   // These functions can be called from any thread.
  86   void AddChildRefreshTimer(VsyncObserver* aVsyncObserver);
  87   void RemoveChildRefreshTimer(VsyncObserver* aVsyncObserver);
  88
  89  private:
  90   virtual ~RefreshTimerVsyncDispatcher();
  91   void UpdateVsyncStatus();
  92   bool NeedsVsync();
  93
  94   Mutex mRefreshTimersLock;
  95   RefPtr<VsyncObserver> mParentRefreshTimer;
  96   nsTArray<RefPtr<VsyncObserver>> mChildRefreshTimers;
  97 };
  98
  99 }  // namespace mozilla
 100
 101 #endif  // mozilla_widget_VsyncDispatcher_h