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// 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 CHROMECAST_BASE_SYSTEM_TIME_CHANGE_NOTIFIER_H_
#define CHROMECAST_BASE_SYSTEM_TIME_CHANGE_NOTIFIER_H_
#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list_threadsafe.h"
#include "base/time/time.h"
namespace base {
class SequencedTaskRunner;
}
namespace chromecast {
// Abstract class to notify system time changes.
class SystemTimeChangeNotifier {
public:
class Observer {
public:
// Called when current system time has changed.
virtual void OnSystemTimeChanged() = 0;
protected:
virtual ~Observer() {}
};
virtual ~SystemTimeChangeNotifier();
virtual void Initialize() = 0;
virtual void Finalize() = 0;
void AddObserver(Observer* observer);
void RemoveObserver(Observer* observer);
protected:
SystemTimeChangeNotifier();
// Implementations are expected to call this to notify system time changes.
void NotifySystemTimeChanged();
private:
scoped_refptr<base::ObserverListThreadSafe<Observer>> observer_list_;
DISALLOW_COPY_AND_ASSIGN(SystemTimeChangeNotifier);
};
// Default implementation of SystemTimeChangeNotifier for most platform.
// It monitors system time changes periodically and notifies if the current
// system time is different from the expected one by more than 10 seconds.
// After reboot or system time has changed, it checks for time changes every
// second for first 1 minute. Then, checks every 10 seconds for next 10 minutes.
// Then, checks every 10 minutes.
class SystemTimeChangeNotifierPeriodicMonitor
: public SystemTimeChangeNotifier {
public:
explicit SystemTimeChangeNotifierPeriodicMonitor(
const scoped_refptr<base::SequencedTaskRunner>& task_runner);
~SystemTimeChangeNotifierPeriodicMonitor() override;
// SystemTimeChangeNotifier implementation:
void Initialize() override;
void Finalize() override;
// For unittests.
void set_fake_now_for_testing(base::Time now) { fake_now_ = now; }
private:
// Helper functions to monitor system time changes.
void ResetTimeAndLimits(base::Time now);
void ScheduleNextMonitor(base::Time now);
void CheckSystemTime();
// Returns base::Time::Now() unless fake_now is set.
base::Time Now() const;
const scoped_refptr<base::SequencedTaskRunner> task_runner_;
base::Time expected_system_time_;
base::Time monitoring_limit_time_1sec_;
base::Time monitoring_limit_time_10sec_;
base::Time fake_now_;
base::WeakPtrFactory<SystemTimeChangeNotifierPeriodicMonitor> weak_factory_;
DISALLOW_COPY_AND_ASSIGN(SystemTimeChangeNotifierPeriodicMonitor);
};
} // namespace chromecast
#endif // CHROMECAST_BASE_SYSTEM_TIME_CHANGE_NOTIFIER_H_
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