athena/resource_manager/public/resource_manager.h

   1 // Copyright 2014 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 ATHENA_RESOURCE_MANAGER_PUBLIC_RESOURCE_MANAGER_H_
   6 #define ATHENA_RESOURCE_MANAGER_PUBLIC_RESOURCE_MANAGER_H_
   7
   8 #include "athena/athena_export.h"
   9 #include "athena/resource_manager/memory_pressure_notifier.h"
  10 #include "base/basictypes.h"
  11
  12 namespace athena {
  13
  14 // The resource manager is monitoring activity changes, low memory conditions
  15 // and other events to control the activity state (pre-/un-/re-/loading them)
  16 // to keep enough memory free that no jank/lag will show when new applications
  17 // are loaded and / or a navigation between applications takes place.
  18 class ATHENA_EXPORT ResourceManager {
  19  public:
  20   // Creates the instance handling the resources.
  21   static void Create();
  22   static ResourceManager* Get();
  23   static void Shutdown();
  24
  25   ResourceManager();
  26   virtual ~ResourceManager();
  27
  28   // Unit tests can simulate MemoryPressure changes with this call.
  29   // Note: Even though the default unit test ResourceManagerDelegte
  30   // implementation ensures that the MemoryPressure event will not go off,
  31   // this call will also explicitly stop the MemoryPressureNotifier.
  32   virtual void SetMemoryPressureAndStopMonitoring(
  33       MemoryPressureObserver::MemoryPressure pressure) = 0;
  34
  35   // Suspend the resource manager temporarily if |pause| is set. This can be
  36   // called before e.g. re-arranging the order of activities. Once called with
  37   // |pause| == false any queued operations will be performed and the resource
  38   // manager will continue its work.
  39   virtual void Pause(bool pause) = 0;
  40
  41  private:
  42   DISALLOW_COPY_AND_ASSIGN(ResourceManager);
  43 };
  44
  45 // Use this scoped object to pause/restart the resource manager.
  46 class ScopedPauseResourceManager {
  47  public:
  48   ScopedPauseResourceManager() {
  49     ResourceManager::Get()->Pause(true);
  50   }
  51   ~ScopedPauseResourceManager() {
  52     ResourceManager::Get()->Pause(false);
  53   }
  54  private:
  55   DISALLOW_COPY_AND_ASSIGN(ScopedPauseResourceManager);
  56 };
  57
  58 }  // namespace athena
  59
  60 #endif  // ATHENA_RESOURCE_MANAGER_PUBLIC_RESOURCE_MANAGER_H_