109 lines
4.2 KiB
C
109 lines
4.2 KiB
C
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// Copyright 2022 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_POWER_MONITOR_BATTERY_STATE_SAMPLER_H_
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#define BASE_POWER_MONITOR_BATTERY_STATE_SAMPLER_H_
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#include <memory>
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#include <vector>
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#include "base/base_export.h"
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#include "base/observer_list.h"
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#include "base/observer_list_types.h"
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#include "base/power_monitor/battery_level_provider.h"
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#include "base/power_monitor/power_monitor_buildflags.h"
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#include "base/power_monitor/sampling_event_source.h"
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#include "base/sequence_checker.h"
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#include "third_party/abseil-cpp/absl/types/optional.h"
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namespace base {
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// Periodically samples the battery and notifies its observers.
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class BASE_EXPORT BatteryStateSampler {
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public:
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class Observer : public base::CheckedObserver {
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public:
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// Note: The first sample taken by the BatteryStateSampler may be out of
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// date (i.e. represent the battery state at an earlier time). Observers
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// that want to ignore those stale samples should ignore the first call to
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// OnBatteryStateSampled.
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virtual void OnBatteryStateSampled(
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const absl::optional<BatteryLevelProvider::BatteryState>&
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battery_state) = 0;
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};
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// Creates a BatteryStateSampler and initializes the global instance. Will
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// DCHECK if an instance already exists.
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BatteryStateSampler(
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std::unique_ptr<SamplingEventSource> sampling_event_source =
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CreateSamplingEventSource(),
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std::unique_ptr<BatteryLevelProvider> battery_level_provider =
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BatteryLevelProvider::Create());
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~BatteryStateSampler();
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// Returns the unique instance, or nullptr on platforms without a
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// `BatteryLevelProvider` implementation.
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static BatteryStateSampler* Get();
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// Adds/removes an observer. `OnBatteryStateSampled` will be immediately
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// invoked upon adding an observer if an existing sample exists already.
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void AddObserver(Observer* observer);
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void RemoveObserver(Observer* observer);
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// Shuts down this instance but doesn't destroy it. This allows it to remain
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// alive for its observers to deregister as they are destroyed without causing
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// use-after-frees, but it won't serve any samples after this is called.
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// Invoked in `PostMainMessageLoopRun`.
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void Shutdown();
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// Creates, installs, and returns an instance of the sampler for testing.
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// This is meant to be used in browser tests before browser init to control
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// the sampler's behavior in the tests.
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static std::unique_ptr<base::BatteryStateSampler> CreateInstanceForTesting(
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std::unique_ptr<SamplingEventSource> sampling_event_source,
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std::unique_ptr<BatteryLevelProvider> battery_level_provider);
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// Returns true if a sampler has been created using `CreateInstanceForTesting`
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static bool HasTestingInstance();
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private:
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// Returns a platform specific SamplingEventSource.
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static std::unique_ptr<SamplingEventSource> CreateSamplingEventSource();
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// Called when the first battery sampled is obtained. Notifies current
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// observers as they are waiting on the cached battery state.
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void OnInitialBatteryStateSampled(
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const absl::optional<BatteryLevelProvider::BatteryState>& battery_state);
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// Triggers the sampling of the battery state.
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void OnSamplingEvent();
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// Notifies observers of the sampled battery state.
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void OnBatteryStateSampled(
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const absl::optional<BatteryLevelProvider::BatteryState>& battery_state);
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std::unique_ptr<SamplingEventSource> sampling_event_source_
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GUARDED_BY_CONTEXT(sequence_checker_);
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std::unique_ptr<BatteryLevelProvider> battery_level_provider_
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GUARDED_BY_CONTEXT(sequence_checker_);
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base::ObserverList<Observer> observer_list_
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GUARDED_BY_CONTEXT(sequence_checker_);
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// Indicates if |last_battery_state_| contains an actual sample. Note: a
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// separate bool is used to avoid nested optionals.
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bool has_last_battery_state_ GUARDED_BY_CONTEXT(sequence_checker_) = false;
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// The value of the last sample taken.
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absl::optional<BatteryLevelProvider::BatteryState> last_battery_state_
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GUARDED_BY_CONTEXT(sequence_checker_);
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SEQUENCE_CHECKER(sequence_checker_);
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};
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} // namespace base
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#endif // BASE_POWER_MONITOR_BATTERY_STATE_SAMPLER_H_
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