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
  15 namespace mozilla {
  16
  17 class VsyncObserver
  18 {
  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(TimeStamp aVsyncTimestamp) = 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 {
  48   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorVsyncDispatcher)
  49
  50 public:
  51   CompositorVsyncDispatcher();
  52
  53   // Called on the vsync thread when a hardware vsync occurs
  54   void NotifyVsync(TimeStamp aVsyncTimestamp);
  55
  56   // Compositor vsync observers must be added/removed on the compositor thread
  57   void SetCompositorVsyncObserver(VsyncObserver* aVsyncObserver);
  58   void Shutdown();
  59
  60 private:
  61   virtual ~CompositorVsyncDispatcher();
  62   void ObserveVsync(bool aEnable);
  63
  64   Mutex mCompositorObserverLock;
  65   RefPtr<VsyncObserver> mCompositorVsyncObserver;
  66   bool mDidShutdown;
  67 };
  68
  69 // Dispatch vsync event to ipc actor parent and chrome RefreshTimer.
  70 class RefreshTimerVsyncDispatcher final
  71 {
  72   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(RefreshTimerVsyncDispatcher)
  73
  74 public:
  75   RefreshTimerVsyncDispatcher();
  76
  77   // Please check CompositorVsyncDispatcher::NotifyVsync().
  78   void NotifyVsync(TimeStamp aVsyncTimestamp);
  79
  80   // Set chrome process's RefreshTimer to this dispatcher.
  81   // This function can be called from any thread.
  82   void SetParentRefreshTimer(VsyncObserver* aVsyncObserver);
  83
  84   // Add or remove the content process' RefreshTimer to this dispatcher. This
  85   // will be a no-op for AddChildRefreshTimer() if the observer is already
  86   // registered.
  87   // These functions can be called from any thread.
  88   void AddChildRefreshTimer(VsyncObserver* aVsyncObserver);
  89   void RemoveChildRefreshTimer(VsyncObserver* aVsyncObserver);
  90
  91 private:
  92   virtual ~RefreshTimerVsyncDispatcher();
  93   void UpdateVsyncStatus();
  94   bool NeedsVsync();
  95
  96   Mutex mRefreshTimersLock;
  97   RefPtr<VsyncObserver> mParentRefreshTimer;
  98   nsTArray<RefPtr<VsyncObserver>> mChildRefreshTimers;
  99 };
 100
 101 } // namespace mozilla
 102
 103 #endif // mozilla_widget_VsyncDispatcher_h