base/memory/memory_pressure_monitor.h

   1 // Copyright 2015 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 BASE_MEMORY_MEMORY_PRESSURE_MONITOR_H_
   6 #define BASE_MEMORY_MEMORY_PRESSURE_MONITOR_H_
   7
   8 #include "base/base_export.h"
   9 #include "base/memory/memory_pressure_listener.h"
  10
  11 namespace base {
  12
  13 // TODO(chrisha): Make this a concrete class with per-OS implementations rather
  14 // than an abstract base class.
  15
  16 // Declares the interface for a MemoryPressureMonitor. There are multiple
  17 // OS specific implementations of this class. An instance of the memory
  18 // pressure observer is created at the process level, tracks memory usage, and
  19 // pushes memory state change notifications to the static function
  20 // base::MemoryPressureListener::NotifyMemoryPressure. This is turn notifies
  21 // all MemoryPressureListener instances via a callback.
  22 class BASE_EXPORT MemoryPressureMonitor {
  23  public:
  24   using MemoryPressureLevel = base::MemoryPressureListener::MemoryPressureLevel;
  25
  26   virtual ~MemoryPressureMonitor();
  27
  28   // Return the singleton MemoryPressureMonitor.
  29   static MemoryPressureMonitor* Get();
  30
  31   // Returns the currently observed memory pressure.
  32   virtual MemoryPressureLevel GetCurrentPressureLevel() const = 0;
  33
  34  protected:
  35   MemoryPressureMonitor();
  36
  37  private:
  38   DISALLOW_COPY_AND_ASSIGN(MemoryPressureMonitor);
  39 };
  40
  41 }  // namespace base
  42
  43 #endif  // BASE_MEMORY_MEMORY_PRESSURE_MONITOR_H_