blob: 1a2f01581ee961bc15acb0ed2291bface2026e85 [file] [log] [blame]
// Copyright 2013 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.
#include "base/base_export.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/no_destructor.h"
#include "base/observer_list_threadsafe.h"
#include "base/power_monitor/power_observer.h"
namespace base {
class PowerMonitorSource;
// A class used to monitor the power state change and notify the observers about
// the change event. The threading model of this class is as follows:
// Once initialized, it is threadsafe. However, the client must ensure that
// initialization happens before any other methods are invoked, including
// IsInitialized(). IsInitialized() exists only as a convenience for detection
// of test contexts where the PowerMonitor global is never created.
class BASE_EXPORT PowerMonitor {
// Initializes global PowerMonitor state. Takes ownership of |source|, which
// will be leaked on process teardown. May only be called once. Not threadsafe
// - no other PowerMonitor methods may be called on any thread while calling
// Initialize(). |source| must not be nullptr.
static void Initialize(std::unique_ptr<PowerMonitorSource> source);
// Returns true if Initialize() has been called. Safe to call on any thread,
// but must not be called while Initialize() or ShutdownForTesting() is being
// invoked.
static bool IsInitialized();
// Add and remove an observer.
// Can be called from any thread. |observer| is notified on the sequence
// from which it was registered.
// Must not be called from within a notification callback.
// AddObserver() fails and returns false if PowerMonitor::Initialize() has not
// been invoked. Failure should only happen in unit tests, where the
// PowerMonitor is generally not initialized. It is safe to call
// RemoveObserver with a PowerObserver that was not successfully added as an
// observer.
static bool AddObserver(PowerObserver* observer);
static void RemoveObserver(PowerObserver* observer);
// Is the computer currently on battery power. May only be called if the
// PowerMonitor has been initialized.
static bool IsOnBatteryPower();
// Uninitializes the PowerMonitor. Should be called at the end of any unit
// test that mocks out the PowerMonitor, to avoid affecting subsequent tests.
// There must be no live PowerObservers when invoked. Safe to call even if the
// PowerMonitor hasn't been initialized.
static void ShutdownForTesting();
friend class PowerMonitorSource;
friend class base::NoDestructor<PowerMonitor>;
static PowerMonitorSource* Source();
static void NotifyPowerStateChange(bool battery_in_use);
static void NotifySuspend();
static void NotifyResume();
static PowerMonitor* GetInstance();
scoped_refptr<ObserverListThreadSafe<PowerObserver>> observers_;
std::unique_ptr<PowerMonitorSource> source_;
} // namespace base