1 /*
2  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 #ifndef SYSTEM_WRAPPERS_INCLUDE_CLOCK_H_
12 #define SYSTEM_WRAPPERS_INCLUDE_CLOCK_H_
13 
14 #include <stdint.h>
15 
16 #include <memory>
17 
18 #include "api/units/timestamp.h"
19 #include "rtc_base/synchronization/rw_lock_wrapper.h"
20 #include "rtc_base/system/rtc_export.h"
21 #include "system_wrappers/include/ntp_time.h"
22 
23 namespace webrtc {
24 
25 // January 1970, in NTP seconds.
26 const uint32_t kNtpJan1970 = 2208988800UL;
27 
28 // Magic NTP fractional unit.
29 const double kMagicNtpFractionalUnit = 4.294967296E+9;
30 
31 // A clock interface that allows reading of absolute and relative timestamps.
32 class RTC_EXPORT Clock {
33  public:
~Clock()34   virtual ~Clock() {}
35   // Return a timestamp relative to an unspecified epoch.
CurrentTime()36   virtual Timestamp CurrentTime() {
37     return Timestamp::Micros(TimeInMicroseconds());
38   }
TimeInMilliseconds()39   virtual int64_t TimeInMilliseconds() { return CurrentTime().ms(); }
TimeInMicroseconds()40   virtual int64_t TimeInMicroseconds() { return CurrentTime().us(); }
41 
42   // Retrieve an NTP absolute timestamp.
43   virtual NtpTime CurrentNtpTime() = 0;
44 
45   // Retrieve an NTP absolute timestamp in milliseconds.
46   virtual int64_t CurrentNtpInMilliseconds() = 0;
47 
48   // Converts an NTP timestamp to a millisecond timestamp.
NtpToMs(uint32_t seconds,uint32_t fractions)49   static int64_t NtpToMs(uint32_t seconds, uint32_t fractions) {
50     return NtpTime(seconds, fractions).ToMs();
51   }
52 
53   // Returns an instance of the real-time system clock implementation.
54   static Clock* GetRealTimeClock();
55 };
56 
57 class SimulatedClock : public Clock {
58  public:
59   explicit SimulatedClock(int64_t initial_time_us);
60   explicit SimulatedClock(Timestamp initial_time);
61 
62   ~SimulatedClock() override;
63 
64   // Return a timestamp relative to some arbitrary source; the source is fixed
65   // for this clock.
66   Timestamp CurrentTime() override;
67 
68   // Retrieve an NTP absolute timestamp.
69   NtpTime CurrentNtpTime() override;
70 
71   // Converts an NTP timestamp to a millisecond timestamp.
72   int64_t CurrentNtpInMilliseconds() override;
73 
74   // Advance the simulated clock with a given number of milliseconds or
75   // microseconds.
76   void AdvanceTimeMilliseconds(int64_t milliseconds);
77   void AdvanceTimeMicroseconds(int64_t microseconds);
78   void AdvanceTime(TimeDelta delta);
79 
80  private:
81   Timestamp time_;
82   std::unique_ptr<RWLockWrapper> lock_;
83 };
84 
85 }  // namespace webrtc
86 
87 #endif  // SYSTEM_WRAPPERS_INCLUDE_CLOCK_H_
88