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 // Declares the interface for a MemoryPressureMonitor. There are multiple
  14 // OS specific implementations of this class. An instance of the memory
  15 // pressure observer is created at the process level, tracks memory usage, and
  16 // pushes memory state change notifications to the static function
  17 // base::MemoryPressureListener::NotifyMemoryPressure. This is turn notifies
  18 // all MemoryPressureListener instances via a callback.
  19 class BASE_EXPORT MemoryPressureMonitor {
  20  public:
  21   using MemoryPressureLevel = base::MemoryPressureListener::MemoryPressureLevel;
  22
  23   // Return the singleton MemoryPressureMonitor.
  24   static MemoryPressureMonitor* Get();
  25
  26   // Returns the currently observed memory pressure.
  27   virtual MemoryPressureLevel GetCurrentPressureLevel() const = 0;
  28
  29  protected:
  30   MemoryPressureMonitor();
  31   virtual ~MemoryPressureMonitor();
  32
  33  private:
  34   DISALLOW_COPY_AND_ASSIGN(MemoryPressureMonitor);
  35 };
  36
  37 }  // namespace base
  38
  39 #endif  // BASE_MEMORY_MEMORY_PRESSURE_MONITOR_H_