| // Copyright 2015 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef COMPONENTS_MEMORY_PRESSURE_FILTERED_MEMORY_PRESSURE_CALCULATOR_H_ |
| #define COMPONENTS_MEMORY_PRESSURE_FILTERED_MEMORY_PRESSURE_CALCULATOR_H_ |
| |
| #include "base/time/tick_clock.h" |
| #include "components/memory_pressure/memory_pressure_calculator.h" |
| |
| namespace memory_pressure { |
| |
| #if defined(MEMORY_PRESSURE_IS_POLLING) |
| |
| // A utility class that provides rate-limiting and hysteresis on raw memory |
| // pressure calculations. This is identical across all platforms, but only used |
| // on those that do not have native memory pressure signals. |
| class FilteredMemoryPressureCalculator : public MemoryPressureCalculator { |
| public: |
| // The minimum time that must pass between successive polls. This enforces an |
| // upper bound on the rate of calls to the contained MemoryPressureCalculator. |
| static const int kMinimumTimeBetweenSamplesMs; |
| |
| // The cooldown period when transitioning from critical to moderate/no memory |
| // pressure, or from moderate to none. |
| static const int kCriticalPressureCooldownPeriodMs; |
| static const int kModeratePressureCooldownPeriodMs; |
| |
| explicit FilteredMemoryPressureCalculator( |
| scoped_ptr<MemoryPressureCalculator> pressure_calculator); |
| ~FilteredMemoryPressureCalculator() override; |
| |
| // Calculates the current pressure level. |
| MemoryPressureLevel CalculateCurrentPressureLevel() override; |
| |
| // Testing seam for configuring the tick clock in use. |
| void set_tick_clock(scoped_ptr<base::TickClock> tick_clock) { |
| tick_clock_ = tick_clock.Pass(); |
| } |
| |
| // Accessors for unittesting. |
| bool cooldown_in_progress() const { return cooldown_in_progress_; } |
| base::TimeTicks cooldown_start_time() const { return cooldown_start_time_; } |
| MemoryPressureLevel cooldown_high_tide() const { return cooldown_high_tide_; } |
| |
| private: |
| friend class TestFilteredMemoryPressureCalculator; |
| |
| // The delegate tick clock. This is settable as a testing seam. |
| scoped_ptr<base::TickClock> tick_clock_; |
| |
| // The delegate pressure calculator. Provided by the constructor. |
| scoped_ptr<MemoryPressureCalculator> pressure_calculator_; |
| |
| // The memory pressure currently being reported. |
| MemoryPressureLevel current_pressure_level_; |
| |
| // The last time a sample was taken. |
| bool samples_taken_; |
| base::TimeTicks last_sample_time_; |
| |
| // State of an ongoing cooldown period, if any. The high-tide line indicates |
| // the highest memory pressure level (*below* the current one) that was |
| // encountered during the cooldown period. This allows a cooldown to |
| // transition directly from critical to none if *no* moderate pressure signals |
| // were seen during the period, otherwise it forces it to pass through a |
| // moderate cooldown as well. |
| bool cooldown_in_progress_; |
| base::TimeTicks cooldown_start_time_; |
| MemoryPressureLevel cooldown_high_tide_; |
| |
| DISALLOW_COPY_AND_ASSIGN(FilteredMemoryPressureCalculator); |
| }; |
| |
| #endif // defined(MEMORY_PRESSURE_IS_POLLING) |
| |
| } // namespace memory_pressure |
| |
| #endif // COMPONENTS_MEMORY_PRESSURE_FILTERED_MEMORY_PRESSURE_CALCULATOR_H_ |