| // Copyright 2014 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_NETWORK_TIME_NETWORK_TIME_TRACKER_H_ |
| #define COMPONENTS_NETWORK_TIME_NETWORK_TIME_TRACKER_H_ |
| |
| #include "base/memory/scoped_ptr.h" |
| #include "base/threading/thread_checker.h" |
| #include "base/time/time.h" |
| |
| class PrefRegistrySimple; |
| class PrefService; |
| |
| namespace base { |
| class TickClock; |
| } |
| |
| namespace network_time { |
| |
| // A class that receives network time updates and can provide the network time |
| // for a corresponding local time. This class is not thread safe. |
| class NetworkTimeTracker { |
| public: |
| static void RegisterPrefs(PrefRegistrySimple* registry); |
| |
| NetworkTimeTracker(scoped_ptr<base::TickClock> tick_clock, |
| PrefService* pref_service); |
| ~NetworkTimeTracker(); |
| |
| // Returns the network time corresponding to |time_ticks| if network time |
| // is available. Returns false if no network time is available yet. Can also |
| // return the error range if |uncertainty| isn't NULL. |
| bool GetNetworkTime(base::TimeTicks time_ticks, |
| base::Time* network_time, |
| base::TimeDelta* uncertainty) const; |
| |
| // Calculates corresponding time ticks according to the given parameters. |
| // The provided |network_time| is precise at the given |resolution| and |
| // represent the time between now and up to |latency| + (now - |post_time|) |
| // ago. |
| void UpdateNetworkTime(base::Time network_time, |
| base::TimeDelta resolution, |
| base::TimeDelta latency, |
| base::TimeTicks post_time); |
| |
| bool received_network_time() const { |
| return received_network_time_; |
| } |
| |
| private: |
| // For querying current time ticks. |
| scoped_ptr<base::TickClock> tick_clock_; |
| |
| PrefService* pref_service_; |
| |
| // Network time based on last call to UpdateNetworkTime(). |
| base::Time network_time_; |
| |
| // The estimated local time from |tick_clock| that corresponds with |
| // |network_time|. Assumes the actual network time measurement was performed |
| // midway through the latency time, and does not account for suspect/resume |
| // events since the network time was measured. |
| // See UpdateNetworkTime(..) implementation for details. |
| base::TimeTicks network_time_ticks_; |
| |
| // Uncertainty of |network_time_| based on added inaccuracies/resolution. |
| // See UpdateNetworkTime(..) implementation for details. |
| base::TimeDelta network_time_uncertainty_; |
| |
| base::ThreadChecker thread_checker_; |
| |
| bool received_network_time_; |
| |
| DISALLOW_COPY_AND_ASSIGN(NetworkTimeTracker); |
| }; |
| |
| } // namespace network_time |
| |
| #endif // COMPONENTS_NETWORK_TIME_NETWORK_TIME_TRACKER_H_ |