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#ifndef MOZC_BASE_STOPWATCH_H_
#define MOZC_BASE_STOPWATCH_H_

#include <cstdint>

#include "base/port.h"

namespace mozc {

class Stopwatch {
 public:
  enum StopwatchState {
    STOPWATCH_RUNNING,
    STOPWATCH_STOPPED,
  };

  // Initializes a new stopwatch object, starts measuring elapsed time,
  // and returns the stopwatch object.
  static Stopwatch StartNew();

  Stopwatch();

  // Sets elapsed time to zero.
  // Stops the time counting.
  void Reset();

  // (Re)starts the time counting.
  // This function does not reset elapsed time so that you can use Start()
  // to accumulate a periodic activity.
  void Start();

  // Stops the time counting.
  // This function does not reset elapsed time so that you can use Start()
  // to accumulate a periodic activity.
  void Stop();

  // Returns the elapsed time as millisecond.
  int64_t GetElapsedMilliseconds();

  // Returns the elapsed time as microsecond.
  double GetElapsedMicroseconds();

  // Returns the elapsed time as nanosecond.
  double GetElapsedNanoseconds();

  // Returns the elapsed time as ticks.
  int64_t GetElapsedTicks();

  // Returns true if the time counting is on-going.
  bool IsRunning() const;

 private:
  StopwatchState state_;
  int64_t frequency_;
  int64_t start_timestamp_;
  int64_t elapsed_timestamp_;
};

}  // namespace mozc

#endif  // MOZC_BASE_STOPWATCH_H_
