content/browser/renderer_host/renderer_frame_manager.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDERER_FRAME_MANAGER_H_
   6 #define CONTENT_BROWSER_RENDERER_HOST_RENDERER_FRAME_MANAGER_H_
   7
   8 #include <list>
   9 #include <map>
  10
  11 #include "base/basictypes.h"
  12 #include "base/memory/memory_pressure_listener.h"
  13 #include "base/memory/singleton.h"
  14 #include "content/common/content_export.h"
  15
  16 namespace content {
  17
  18 class RenderWidgetHostViewAuraTest;
  19
  20 class CONTENT_EXPORT RendererFrameManagerClient {
  21  public:
  22   virtual ~RendererFrameManagerClient() {}
  23   virtual void EvictCurrentFrame() = 0;
  24 };
  25
  26 // This class is responsible for globally managing which renderers keep their
  27 // compositor frame when offscreen. We actively discard compositor frames for
  28 // offscreen tabs, but keep a minimum amount, as an LRU cache, to make switching
  29 // between a small set of tabs faster. The limit is a soft limit, because
  30 // clients can lock their frame to prevent it from being discarded, e.g. if the
  31 // tab is visible, or while capturing a screenshot.
  32 class CONTENT_EXPORT RendererFrameManager {
  33  public:
  34   static RendererFrameManager* GetInstance();
  35
  36   void AddFrame(RendererFrameManagerClient*, bool locked);
  37   void RemoveFrame(RendererFrameManagerClient*);
  38   void LockFrame(RendererFrameManagerClient*);
  39   void UnlockFrame(RendererFrameManagerClient*);
  40
  41   size_t GetMaxNumberOfSavedFrames() const;
  42
  43   // For testing only
  44   void set_max_handles(float max_handles) { max_handles_ = max_handles; }
  45
  46  private:
  47   // Please remove when crbug.com/443824 has been fixed.
  48   friend class RenderWidgetHostViewAuraTest;
  49
  50   RendererFrameManager();
  51   ~RendererFrameManager();
  52   void CullUnlockedFrames(size_t saved_frame_limit);
  53
  54   // React on memory pressure events to adjust the number of cached frames.
  55   void OnMemoryPressure(
  56       base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
  57
  58   friend struct DefaultSingletonTraits<RendererFrameManager>;
  59
  60   // Listens for system under pressure notifications and adjusts number of
  61   // cached frames accordingly.
  62   base::MemoryPressureListener memory_pressure_listener_;
  63
  64   std::map<RendererFrameManagerClient*, size_t> locked_frames_;
  65   std::list<RendererFrameManagerClient*> unlocked_frames_;
  66   size_t max_number_of_saved_frames_;
  67   float max_handles_;
  68
  69   DISALLOW_COPY_AND_ASSIGN(RendererFrameManager);
  70 };
  71
  72 }  // namespace content
  73
  74 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDERER_FRAME_MANAGER_H_