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).
32 MEMORY_PRESSURE_UNKNOWN
, // The memory pressure cannot be determined.
33 MEMORY_PRESSURE_LOW
, // Single call if memory fill level is below 50%.
34 MEMORY_PRESSURE_MODERATE
, // Polled for memory fill level of ~50 .. 75%.
35 MEMORY_PRESSURE_HIGH
, // Polled for memory fill level of ~75% .. 90%.
36 MEMORY_PRESSURE_CRITICAL
, // Polled for memory fill level of above ~90%.
39 virtual void OnMemoryPressure(MemoryPressure pressure
) = 0;
41 // OS system interface functions. The delegate remains owned by the Observer.
42 virtual ResourceManagerDelegate
* GetDelegate() = 0;
46 ////////////////////////////////////////////////////////////////////////////////
47 // MemoryPressureNotifier
49 // Class to handle the observation of our free memory. It notifies the owner of
50 // memory fill level changes, so that it can take action to reduce memory by
51 // reducing active activities.
53 // The observer will use 3 different fill levels: 50% full, 75% full and 90%
55 class ATHENA_EXPORT MemoryPressureNotifier
{
57 // The creator gets the |listener| object. Note that the ownership of the
58 // listener object remains with the creator.
59 explicit MemoryPressureNotifier(MemoryPressureObserver
* listener
);
60 ~MemoryPressureNotifier();
62 // Stop observing the memory fill level.
63 // May be safely called if StartObserving has not been called.
67 // Starts observing the memory fill level.
68 // Calls to StartObserving should always be matched with calls to
70 void StartObserving();
72 // The function which gets periodically be called to check any changes in the
74 void CheckMemoryPressure();
76 // Converts free percent of memory into a memory pressure value.
77 MemoryPressureObserver::MemoryPressure
GetMemoryPressureLevelFromFillLevel(
78 int memory_fill_level
);
80 base::RepeatingTimer
<MemoryPressureNotifier
> timer_
;
82 // The listener which needs to be informed about memory pressure.
83 MemoryPressureObserver
* listener_
;
85 // Our current memory pressure.
86 MemoryPressureObserver::MemoryPressure current_pressure_
;
88 DISALLOW_COPY_AND_ASSIGN(MemoryPressureNotifier
);
93 #endif // ATHENA_RESOURCE_MANAGER_MEMORY_PRESSURE_NOTIFIER_H_