Repo created

TMessagesProj/jni/voip/webrtc/system_wrappers/include/clock.h

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+/*
+ *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef SYSTEM_WRAPPERS_INCLUDE_CLOCK_H_
+#define SYSTEM_WRAPPERS_INCLUDE_CLOCK_H_
+
+#include <stdint.h>
+
+#include <atomic>
+#include <memory>
+
+#include "api/units/timestamp.h"
+#include "rtc_base/system/rtc_export.h"
+#include "system_wrappers/include/ntp_time.h"
+
+namespace webrtc {
+
+// January 1970, in NTP seconds.
+const uint32_t kNtpJan1970 = 2208988800UL;
+
+// Magic NTP fractional unit.
+const double kMagicNtpFractionalUnit = 4.294967296E+9;
+
+// A clock interface that allows reading of absolute and relative timestamps.
+class RTC_EXPORT Clock {
+ public:
+  virtual ~Clock() {}
+
+  // Return a timestamp relative to an unspecified epoch.
+  virtual Timestamp CurrentTime() = 0;
+  int64_t TimeInMilliseconds() { return CurrentTime().ms(); }
+  int64_t TimeInMicroseconds() { return CurrentTime().us(); }
+
+  // Retrieve an NTP absolute timestamp (with an epoch of Jan 1, 1900).
+  NtpTime CurrentNtpTime() { return ConvertTimestampToNtpTime(CurrentTime()); }
+  int64_t CurrentNtpInMilliseconds() { return CurrentNtpTime().ToMs(); }
+
+  // Converts between a relative timestamp returned by this clock, to NTP time.
+  virtual NtpTime ConvertTimestampToNtpTime(Timestamp timestamp) = 0;
+  int64_t ConvertTimestampToNtpTimeInMilliseconds(int64_t timestamp_ms) {
+    return ConvertTimestampToNtpTime(Timestamp::Millis(timestamp_ms)).ToMs();
+  }
+
+  // Returns an instance of the real-time system clock implementation.
+  static Clock* GetRealTimeClock();
+};
+
+class SimulatedClock : public Clock {
+ public:
+  // The constructors assume an epoch of Jan 1, 1970.
+  explicit SimulatedClock(int64_t initial_time_us);
+  explicit SimulatedClock(Timestamp initial_time);
+  ~SimulatedClock() override;
+
+  // Return a timestamp with an epoch of Jan 1, 1970.
+  Timestamp CurrentTime() override;
+
+  NtpTime ConvertTimestampToNtpTime(Timestamp timestamp) override;
+
+  // Advance the simulated clock with a given number of milliseconds or
+  // microseconds.
+  void AdvanceTimeMilliseconds(int64_t milliseconds);
+  void AdvanceTimeMicroseconds(int64_t microseconds);
+  void AdvanceTime(TimeDelta delta);
+
+ private:
+  // The time is read and incremented with relaxed order. Each thread will see
+  // monotonically increasing time, and when threads post tasks or messages to
+  // one another, the synchronization done as part of the message passing should
+  // ensure that any causual chain of events on multiple threads also
+  // corresponds to monotonically increasing time.
+  std::atomic<int64_t> time_us_;
+};
+
+}  // namespace webrtc
+
+#endif  // SYSTEM_WRAPPERS_INCLUDE_CLOCK_H_