components/memory_pressure/memory_pressure_stats_collector.h

   1 // Copyright 2015 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 COMPONENTS_MEMORY_PRESSURE_MEMORY_PRESSURE_STATS_COLLECTOR_H_
   6 #define COMPONENTS_MEMORY_PRESSURE_MEMORY_PRESSURE_STATS_COLLECTOR_H_
   7
   8 #include "base/time/time.h"
   9 #include "components/memory_pressure/memory_pressure_listener.h"
  10
  11 namespace base {
  12 class TickClock;
  13 }
  14
  15 namespace memory_pressure {
  16
  17 // Enumeration of UMA memory pressure levels. The pressure level enum defined in
  18 // MemoryPressureListener is non-contiguous. This enum is a contiguous version
  19 // of that for use with UMA. Both it and histograms.xml must be kept in sync
  20 // with the MemoryPressureListener enum. Included in the header so that
  21 // UMA_MEMORY_PRESSURE_LEVEL_COUNT is available.
  22 enum MemoryPressureLevelUMA {
  23   UMA_MEMORY_PRESSURE_LEVEL_NONE = 0,
  24   UMA_MEMORY_PRESSURE_LEVEL_MODERATE = 1,
  25   UMA_MEMORY_PRESSURE_LEVEL_CRITICAL = 2,
  26   // This must be the last value in the enum.
  27   UMA_MEMORY_PRESSURE_LEVEL_COUNT,
  28 };
  29
  30 // Enumeration of UMA pressure level changes. This needs to be kept in sync
  31 // with histograms.xml and the memory pressure levels defined in
  32 // MemoryPressureListener. Exposed for unittesting.
  33 enum MemoryPressureLevelChangeUMA {
  34   UMA_MEMORY_PRESSURE_LEVEL_CHANGE_NONE_TO_MODERATE = 0,
  35   UMA_MEMORY_PRESSURE_LEVEL_CHANGE_NONE_TO_CRITICAL = 1,
  36   UMA_MEMORY_PRESSURE_LEVEL_CHANGE_MODERATE_TO_CRITICAL = 2,
  37   UMA_MEMORY_PRESSURE_LEVEL_CHANGE_CRITICAL_TO_MODERATE = 3,
  38   UMA_MEMORY_PRESSURE_LEVEL_CHANGE_CRITICAL_TO_NONE = 4,
  39   UMA_MEMORY_PRESSURE_LEVEL_CHANGE_MODERATE_TO_NONE = 5,
  40   // This must be the last value in the enum.
  41   UMA_MEMORY_PRESSURE_LEVEL_CHANGE_COUNT
  42 };
  43
  44 // Class that is responsible for collecting and eventually reporting memory
  45 // pressure statistics. Contributes to the "Memory.PressureLevel" and
  46 // "Memory.PressureLevelChanges" histograms.
  47 //
  48 // On platforms with a polling memory pressure implementation the
  49 // UpdateStatistics function will be invoked every time the pressure is polled.
  50 // On non-polling platforms (Mac, Android) it will be invoked on a periodic
  51 // timer, and at the moment of pressure level changes.
  52 class MemoryPressureStatsCollector {
  53  public:
  54   using MemoryPressureLevel = MemoryPressureListener::MemoryPressureLevel;
  55
  56   // The provided |tick_clock| must outlive this class.
  57   MemoryPressureStatsCollector(base::TickClock* tick_clock);
  58
  59   // This is to be called periodically to ensure that up to date statistics
  60   // have been reported.
  61   void UpdateStatistics(MemoryPressureLevel current_pressure_level);
  62
  63  private:
  64   friend class TestMemoryPressureStatsCollector;
  65
  66   // Helper functions for delivering collected statistics.
  67   static void ReportCumulativeTime(MemoryPressureLevel pressure_level,
  68                                    int seconds);
  69   static void ReportLevelChange(MemoryPressureLevel old_pressure_level,
  70                                 MemoryPressureLevel new_pressure_level);
  71
  72   // The tick clock in use. This class is intended to be owned by a class with
  73   // a tick clock, and ownership remains there. Also intended as a test seam.
  74   base::TickClock* tick_clock_;
  75
  76   // Buckets of time that have been spent in different pressure levels, but
  77   // not yet reported. At every call to UpdateStatistics these buckets will be
  78   // drained of as many 'full' seconds of time as possible and reported via
  79   // UMA. The remaining time (< 1000 ms) will be left in the bucket to be rolled
  80   // into a later UMA report.
  81   base::TimeDelta unreported_cumulative_time_[UMA_MEMORY_PRESSURE_LEVEL_COUNT];
  82
  83   // The last observed pressure level and the time at which it was observed, and
  84   // the time when this pressure level started.
  85   MemoryPressureLevel last_pressure_level_;
  86   base::TimeTicks last_update_time_;
  87
  88   DISALLOW_COPY_AND_ASSIGN(MemoryPressureStatsCollector);
  89 };
  90
  91 }  // namespace memory_pressure
  92
  93 #endif  // COMPONENTS_MEMORY_PRESSURE_MEMORY_PRESSURE_STATS_COLLECTOR_H_