ccls/src/timer.h

#pragma once

#include <optional.h>

#include <chrono>
#include <string>

struct Timer {
  using Clock = std::chrono::high_resolution_clock;

  // Creates a new timer. A timer is always running.
  Timer();

  // Returns elapsed microseconds.
  long long ElapsedMicroseconds() const;
  // Returns elapsed microseconds and restarts/resets the timer.
  long long ElapsedMicrosecondsAndReset();
  // Restart/reset the timer.
  void Reset();
  // Resets timer and prints a message like "<foo> took 5ms"
  void ResetAndPrint(const std::string& message);
  // Pause the timer.
  void Pause();
  // Resume the timer after it has been paused.
  void Resume();

  // Raw start time.
  optional<std::chrono::time_point<Clock>> start_;
  // Elapsed time.
  long long elapsed_ = 0;
};

struct ScopedPerfTimer {
  ScopedPerfTimer(const std::string& message);
  ~ScopedPerfTimer();

  Timer timer_;
  std::string message_;
};