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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_MONITOR_H_ | |
6 #define BASE_CHROMEOS_MEMORY_PRESSURE_MONITOR_H_ | |
7 | |
8 #include "base/base_export.h" | |
9 #include "base/files/scoped_file.h" | |
10 #include "base/gtest_prod_util.h" | |
11 #include "base/macros.h" | |
12 #include "base/memory/memory_pressure_listener.h" | |
13 #include "base/memory/memory_pressure_monitor.h" | |
14 #include "base/memory/weak_ptr.h" | |
15 #include "base/timer/timer.h" | |
16 | |
17 namespace base { | |
18 namespace chromeos { | |
19 | |
20 class TestMemoryPressureMonitor; | |
21 | |
22 //////////////////////////////////////////////////////////////////////////////// | |
23 // MemoryPressureMonitor | |
24 // | |
25 // A class to handle the observation of our free memory. It notifies the | |
26 // MemoryPressureListener of memory fill level changes, so that it can take | |
27 // action to reduce memory resources accordingly. | |
28 // | |
29 class BASE_EXPORT MemoryPressureMonitor : public base::MemoryPressureMonitor { | |
30 public: | |
31 using GetUsedMemoryInPercentCallback = int (*)(); | |
32 | |
33 // There are two memory pressure events: | |
34 // MODERATE - which will mainly release caches. | |
35 // CRITICAL - which will discard tabs. | |
36 // The |MemoryPressureThresholds| enum selects the strategy of firing these | |
37 // events: A conservative strategy will keep as much content in memory as | |
38 // possible (causing the system to swap to zram) and an aggressive strategy | |
39 // will release memory earlier to avoid swapping. | |
40 enum MemoryPressureThresholds { | |
41 // Use the system default. | |
42 THRESHOLD_DEFAULT = 0, | |
43 // Try to keep as much content in memory as possible. | |
44 THRESHOLD_CONSERVATIVE = 1, | |
45 // Discard caches earlier, allowing to keep more tabs in memory. | |
46 THRESHOLD_AGGRESSIVE_CACHE_DISCARD = 2, | |
47 // Discard tabs earlier, allowing the system to get faster. | |
48 THRESHOLD_AGGRESSIVE_TAB_DISCARD = 3, | |
49 // Discard caches and tabs earlier to allow the system to be faster. | |
50 THRESHOLD_AGGRESSIVE = 4 | |
51 }; | |
52 | |
53 explicit MemoryPressureMonitor(MemoryPressureThresholds thresholds); | |
54 ~MemoryPressureMonitor() override; | |
55 | |
56 // Redo the memory pressure calculation soon and call again if a critical | |
57 // memory pressure prevails. Note that this call will trigger an asynchronous | |
58 // action which gives the system time to release memory back into the pool. | |
59 void ScheduleEarlyCheck(); | |
60 | |
61 // Get the current memory pressure level. | |
62 MemoryPressureListener::MemoryPressureLevel GetCurrentPressureLevel() const | |
63 override; | |
64 | |
65 // Returns a type-casted version of the current memory pressure monitor. A | |
66 // simple wrapper to base::MemoryPressureMonitor::Get. | |
67 static MemoryPressureMonitor* Get(); | |
68 | |
69 private: | |
70 friend TestMemoryPressureMonitor; | |
71 // Starts observing the memory fill level. | |
72 // Calls to StartObserving should always be matched with calls to | |
73 // StopObserving. | |
74 void StartObserving(); | |
75 | |
76 // Stop observing the memory fill level. | |
77 // May be safely called if StartObserving has not been called. | |
78 void StopObserving(); | |
79 | |
80 // The function which gets periodically called to check any changes in the | |
81 // memory pressure. It will report pressure changes as well as continuous | |
82 // critical pressure levels. | |
83 void CheckMemoryPressure(); | |
84 | |
85 // The function periodically checks the memory pressure changes and records | |
86 // the UMA histogram statistics for the current memory pressure level. | |
87 void CheckMemoryPressureAndRecordStatistics(); | |
88 | |
89 // Get the memory pressure in percent (virtual for testing). | |
90 virtual int GetUsedMemoryInPercent(); | |
91 | |
92 // The current memory pressure. | |
93 base::MemoryPressureListener::MemoryPressureLevel | |
94 current_memory_pressure_level_; | |
95 | |
96 // A periodic timer to check for resource pressure changes. This will get | |
97 // replaced by a kernel triggered event system (see crbug.com/381196). | |
98 base::RepeatingTimer<MemoryPressureMonitor> timer_; | |
99 | |
100 // To slow down the amount of moderate pressure event calls, this counter | |
101 // gets used to count the number of events since the last event occured. | |
102 int moderate_pressure_repeat_count_; | |
103 | |
104 // The thresholds for moderate and critical pressure. | |
105 const int moderate_pressure_threshold_percent_; | |
106 const int critical_pressure_threshold_percent_; | |
107 | |
108 // File descriptor used to detect low memory condition. | |
109 ScopedFD low_mem_file_; | |
110 | |
111 base::WeakPtrFactory<MemoryPressureMonitor> weak_ptr_factory_; | |
112 | |
113 DISALLOW_COPY_AND_ASSIGN(MemoryPressureMonitor); | |
114 }; | |
115 | |
116 } // namespace chromeos | |
117 } // namespace base | |
118 | |
119 #endif // BASE_CHROMEOS_MEMORY_PRESSURE_MONITOR_H_ | |
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