1 // Copyright (c) 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.
5 #ifndef ATHENA_RESOURCE_MANAGER_MEMORY_PRESSURE_NOTIFIER_H_
6 #define ATHENA_RESOURCE_MANAGER_MEMORY_PRESSURE_NOTIFIER_H_
8 #include "athena/athena_export.h"
9 #include "base/memory/ref_counted.h"
10 #include "base/memory/scoped_ptr.h"
11 #include "base/timer/timer.h"
15 class MemoryPressureNotifierImpl;
16 class ResourceManagerDelegate;
18 ////////////////////////////////////////////////////////////////////////////////
19 // MemoryPressureObserver
21 // This observer gets informed once about a |MEMORY_PRESSURE_LOW|. When the
22 // pressure exceeds, the observer will get polled until |MEMORY_PRESSURE_LOW| is
23 // reached again to counter memory consumption.
24 class MemoryPressureObserver {
26 MemoryPressureObserver() {}
27 virtual ~MemoryPressureObserver() {}
29 // The reported memory pressure. Note: The value is intentionally abstracted
30 // since the real amount of free memory is only estimated (due to e.g. zram).
31 // Note: The bigger the index of the pressure level, the more resources are
34 MEMORY_PRESSURE_UNKNOWN = 0, // The memory pressure cannot be determined.
35 MEMORY_PRESSURE_LOW, // Single call if fill level is below 50%.
36 MEMORY_PRESSURE_MODERATE, // Polled for fill level of ~50 .. 75%.
37 MEMORY_PRESSURE_HIGH, // Polled for fill level of ~75% .. 90%.
38 MEMORY_PRESSURE_CRITICAL, // Polled for fill level of above ~90%.
41 virtual void OnMemoryPressure(MemoryPressure pressure) = 0;
43 // OS system interface functions. The delegate remains owned by the Observer.
44 virtual ResourceManagerDelegate* GetDelegate() = 0;
48 ////////////////////////////////////////////////////////////////////////////////
49 // MemoryPressureNotifier
51 // Class to handle the observation of our free memory. It notifies the owner of
52 // memory fill level changes, so that it can take action to reduce memory by
53 // reducing active activities.
55 // The observer will use 3 different fill levels: 50% full, 75% full and 90%
57 class ATHENA_EXPORT MemoryPressureNotifier {
59 // The creator gets the |listener| object. Note that the ownership of the
60 // listener object remains with the creator.
61 explicit MemoryPressureNotifier(MemoryPressureObserver* listener);
62 ~MemoryPressureNotifier();
64 // Stop observing the memory fill level.
65 // May be safely called if StartObserving has not been called.
69 // Starts observing the memory fill level.
70 // Calls to StartObserving should always be matched with calls to
72 void StartObserving();
74 // The function which gets periodically be called to check any changes in the
76 void CheckMemoryPressure();
78 // Converts free percent of memory into a memory pressure value.
79 MemoryPressureObserver::MemoryPressure GetMemoryPressureLevelFromFillLevel(
80 int memory_fill_level);
82 base::RepeatingTimer<MemoryPressureNotifier> timer_;
84 // The listener which needs to be informed about memory pressure.
85 MemoryPressureObserver* listener_;
87 // Our current memory pressure.
88 MemoryPressureObserver::MemoryPressure current_pressure_;
90 DISALLOW_COPY_AND_ASSIGN(MemoryPressureNotifier);
95 #endif // ATHENA_RESOURCE_MANAGER_MEMORY_PRESSURE_NOTIFIER_H_