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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 BASE_CHROMEOS_MEMORY_PRESSURE_OBSERVER_CHROMEOS_H_ | |
6 #define BASE_CHROMEOS_MEMORY_PRESSURE_OBSERVER_CHROMEOS_H_ | |
7 | |
8 #include "base/base_export.h" | |
9 #include "base/gtest_prod_util.h" | |
10 #include "base/macros.h" | |
11 #include "base/memory/memory_pressure_listener.h" | |
12 #include "base/memory/weak_ptr.h" | |
13 #include "base/timer/timer.h" | |
14 | |
15 namespace base { | |
16 | |
17 class TestMemoryPressureObserver; | |
18 | |
19 //////////////////////////////////////////////////////////////////////////////// | |
20 // MemoryPressureObserverChromeOS | |
21 // | |
22 // A class to handle the observation of our free memory. It notifies the | |
23 // MemoryPressureListener of memory fill level changes, so that it can take | |
24 // action to reduce memory resources accordingly. | |
25 // | |
26 class BASE_EXPORT MemoryPressureObserverChromeOS { | |
27 public: | |
28 using GetUsedMemoryInPercentCallback = int (*)(); | |
29 | |
30 // There are two memory pressure events: | |
31 // MODERATE - which will mainly release caches. | |
32 // CRITICAL - which will discard tabs. | |
33 // The |MemoryPressureThresholds| enum selects the strategy of firing these | |
34 // events: A conservative strategy will keep as much content in memory as | |
35 // possible (causing the system to swap to zram) and an aggressive strategy | |
36 // will release memory earlier to avoid swapping. | |
37 enum MemoryPressureThresholds { | |
38 // Use the system default. | |
39 THRESHOLD_DEFAULT = 0, | |
40 // Try to keep as much content in memory as possible. | |
41 THRESHOLD_CONSERVATIVE = 1, | |
42 // Discard caches earlier, allowing to keep more tabs in memory. | |
43 THRESHOLD_AGGRESSIVE_CACHE_DISCARD = 2, | |
44 // Discard tabs earlier, allowing the system to get faster. | |
45 THRESHOLD_AGGRESSIVE_TAB_DISCARD = 3, | |
46 // Discard caches and tabs earlier to allow the system to be faster. | |
47 THRESHOLD_AGGRESSIVE = 4 | |
48 }; | |
49 | |
50 explicit MemoryPressureObserverChromeOS(MemoryPressureThresholds thresholds); | |
51 virtual ~MemoryPressureObserverChromeOS(); | |
52 | |
53 // Redo the memory pressure calculation soon and call again if a critical | |
54 // memory pressure prevails. Note that this call will trigger an asynchronous | |
55 // action which gives the system time to release memory back into the pool. | |
56 void ScheduleEarlyCheck(); | |
57 | |
58 // Get the current memory pressure level. | |
59 base::MemoryPressureListener::MemoryPressureLevel GetCurrentPressureLevel() { | |
60 return current_memory_pressure_level_; | |
61 } | |
62 | |
63 private: | |
64 friend TestMemoryPressureObserver; | |
65 // Starts observing the memory fill level. | |
66 // Calls to StartObserving should always be matched with calls to | |
67 // StopObserving. | |
68 void StartObserving(); | |
69 | |
70 // Stop observing the memory fill level. | |
71 // May be safely called if StartObserving has not been called. | |
72 void StopObserving(); | |
73 | |
74 // The function which gets periodically called to check any changes in the | |
75 // memory pressure. It will report pressure changes as well as continuous | |
76 // critical pressure levels. | |
77 void CheckMemoryPressure(); | |
78 | |
79 // The function periodically checks the memory pressure changes and records | |
80 // the UMA histogram statistics for the current memory pressure level. | |
81 void CheckMemoryPressureAndRecordStatistics(); | |
82 | |
83 // Get the memory pressure in percent (virtual for testing). | |
84 virtual int GetUsedMemoryInPercent(); | |
85 | |
86 // The current memory pressure. | |
87 base::MemoryPressureListener::MemoryPressureLevel | |
88 current_memory_pressure_level_; | |
89 | |
90 // A periodic timer to check for resource pressure changes. This will get | |
91 // replaced by a kernel triggered event system (see crbug.com/381196). | |
92 base::RepeatingTimer<MemoryPressureObserverChromeOS> timer_; | |
93 | |
94 // To slow down the amount of moderate pressure event calls, this counter | |
95 // gets used to count the number of events since the last event occured. | |
96 int moderate_pressure_repeat_count_; | |
97 | |
98 // The thresholds for moderate and critical pressure. | |
99 const int moderate_pressure_threshold_percent_; | |
100 const int critical_pressure_threshold_percent_; | |
101 | |
102 base::WeakPtrFactory<MemoryPressureObserverChromeOS> weak_ptr_factory_; | |
103 | |
104 DISALLOW_COPY_AND_ASSIGN(MemoryPressureObserverChromeOS); | |
105 }; | |
106 | |
107 } // namespace base | |
108 | |
109 #endif // BASE_CHROMEOS_MEMORY_PRESSURE_OBSERVER_CHROMEOS_H_ | |
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