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_MEMORY_MEMORY_PRESSURE_MONITOR_CHROMEOS_H_ 6 #define BASE_MEMORY_MEMORY_PRESSURE_MONITOR_CHROMEOS_H_ 7 8 #include "base/base_export.h" 9 #include "base/files/scoped_file.h" 10 #include "base/macros.h" 11 #include "base/memory/memory_pressure_listener.h" 12 #include "base/memory/memory_pressure_monitor.h" 13 #include "base/memory/weak_ptr.h" 14 #include "base/timer/timer.h" 15 16 namespace base { 17 namespace chromeos { 18 19 class TestMemoryPressureMonitor; 20 21 //////////////////////////////////////////////////////////////////////////////// 22 // MemoryPressureMonitor 23 // 24 // A class to handle the observation of our free memory. It notifies the 25 // MemoryPressureListener of memory fill level changes, so that it can take 26 // action to reduce memory resources accordingly. 27 // 28 class BASE_EXPORT MemoryPressureMonitor : public base::MemoryPressureMonitor { 29 public: 30 using GetUsedMemoryInPercentCallback = int (*)(); 31 32 // There are two memory pressure events: 33 // MODERATE - which will mainly release caches. 34 // CRITICAL - which will discard tabs. 35 // The |MemoryPressureThresholds| enum selects the strategy of firing these 36 // events: A conservative strategy will keep as much content in memory as 37 // possible (causing the system to swap to zram) and an aggressive strategy 38 // will release memory earlier to avoid swapping. 39 enum MemoryPressureThresholds { 40 // Use the system default. 41 THRESHOLD_DEFAULT = 0, 42 // Try to keep as much content in memory as possible. 43 THRESHOLD_CONSERVATIVE = 1, 44 // Discard caches earlier, allowing to keep more tabs in memory. 45 THRESHOLD_AGGRESSIVE_CACHE_DISCARD = 2, 46 // Discard tabs earlier, allowing the system to get faster. 47 THRESHOLD_AGGRESSIVE_TAB_DISCARD = 3, 48 // Discard caches and tabs earlier to allow the system to be faster. 49 THRESHOLD_AGGRESSIVE = 4 50 }; 51 52 explicit MemoryPressureMonitor(MemoryPressureThresholds thresholds); 53 ~MemoryPressureMonitor() override; 54 55 // Redo the memory pressure calculation soon and call again if a critical 56 // memory pressure prevails. Note that this call will trigger an asynchronous 57 // action which gives the system time to release memory back into the pool. 58 void ScheduleEarlyCheck(); 59 60 // Get the current memory pressure level. 61 MemoryPressureListener::MemoryPressureLevel GetCurrentPressureLevel() 62 override; 63 void SetDispatchCallback(const DispatchCallback& callback) 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 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 "Memory.PressureLevel" statistic is recorded every 105 // 5 seconds, but the timer to report "ChromeOS.MemoryPressureLevel" 106 // fires every second. This counter is used to allow reporting 107 // "Memory.PressureLevel" correctly without adding another 108 // timer. 109 int seconds_since_reporting_; 110 111 // The thresholds for moderate and critical pressure. 112 const int moderate_pressure_threshold_percent_; 113 const int critical_pressure_threshold_percent_; 114 115 // File descriptor used to detect low memory condition. 116 ScopedFD low_mem_file_; 117 118 DispatchCallback dispatch_callback_; 119 120 base::WeakPtrFactory<MemoryPressureMonitor> weak_ptr_factory_; 121 122 DISALLOW_COPY_AND_ASSIGN(MemoryPressureMonitor); 123 }; 124 125 } // namespace chromeos 126 } // namespace base 127 128 #endif // BASE_MEMORY_MEMORY_PRESSURE_MONITOR_CHROMEOS_H_ 129