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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_MEMORY_PRESSURE_MULTI_SOURCE_MEMORY_PRESSURE_MONITOR_H_
#define COMPONENTS_MEMORY_PRESSURE_MULTI_SOURCE_MEMORY_PRESSURE_MONITOR_H_
#include "base/memory/memory_pressure_monitor.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "components/memory_pressure/memory_pressure_level_reporter.h"
#include "components/memory_pressure/memory_pressure_voter.h"
namespace memory_pressure {
class SystemMemoryPressureEvaluator;
// This is a specialization of a MemoryPressureMonitor that relies on a set of
// MemoryPressureVoters to determine the memory pressure state. The
// MemoryPressureVoteAggregator is in charge of receiving votes from these
// voters and notifying MemoryPressureListeners of the MemoryPressureLevel via
// the monitor's |dispatch_callback_|. The pressure level is calculated as the
// most critical of all votes collected.
// This class is not thread safe and should be used from a single sequence.
class MultiSourceMemoryPressureMonitor
: public base::MemoryPressureMonitor,
public MemoryPressureVoteAggregator::Delegate {
public:
using MemoryPressureLevel = base::MemoryPressureMonitor::MemoryPressureLevel;
using DispatchCallback = base::MemoryPressureMonitor::DispatchCallback;
MultiSourceMemoryPressureMonitor();
~MultiSourceMemoryPressureMonitor() override;
MultiSourceMemoryPressureMonitor(const MultiSourceMemoryPressureMonitor&) =
delete;
MultiSourceMemoryPressureMonitor& operator=(
const MultiSourceMemoryPressureMonitor&) = delete;
// Start monitoring memory pressure by creating the platform-specific voter.
// Does nothing on ChromeOS & Chromecast, for which there is no default
// system evaluator implementations.
void MaybeStartPlatformVoter();
// MemoryPressureMonitor implementation.
MemoryPressureLevel GetCurrentPressureLevel() const override;
// Creates a MemoryPressureVoter to be owned/used by a source that wishes to
// have input on the overall memory pressure level.
std::unique_ptr<MemoryPressureVoter> CreateVoter();
// Sets the system evaluator on platforms where no default implementation
// exists, because of layering concerns (ChromeOS & Chromecast).
void SetSystemEvaluator(
std::unique_ptr<SystemMemoryPressureEvaluator> evaluator);
// Allows tests to override the call to
// `base::MemoryPressureListener::NotifyMemoryPressure` that is done whenever
// `OnNotifyListenersRequested` is invoked.
void SetDispatchCallbackForTesting(const DispatchCallback& callback);
MemoryPressureVoteAggregator* aggregator_for_testing() {
return &aggregator_;
}
SystemMemoryPressureEvaluator* system_evaluator_for_testing() {
return system_evaluator_.get();
}
private:
// Delegate implementation.
void OnMemoryPressureLevelChanged(MemoryPressureLevel level) override;
void OnNotifyListenersRequested() override;
MemoryPressureLevel current_pressure_level_;
DispatchCallback dispatch_callback_;
MemoryPressureVoteAggregator aggregator_;
std::unique_ptr<SystemMemoryPressureEvaluator> system_evaluator_;
// The timestamp of the last pressure change event.
base::TimeTicks last_pressure_change_timestamp_;
MemoryPressureLevelReporter level_reporter_;
SEQUENCE_CHECKER(sequence_checker_);
};
} // namespace memory_pressure
#endif // COMPONENTS_MEMORY_PRESSURE_MULTI_SOURCE_MEMORY_PRESSURE_MONITOR_H_
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