std::this_thread::sleep_for with custom accelerated clock

Question

I have many instances of std::this_thread::sleep_for(remaining_loop_time_duration).

To speed up simulation, we now were asked to use a special custom clock reference (queried using GetSimTime), which runs faster than real-time by a factor > 1.0.

To avoid large restructuring of my code I simply want to use a custom clock like this:

struct speedy_clock {
  using duration = std::chrono::microseconds;
  using rep = duration::rep;
  using period = duration::period;
  using time_point = std::chrono::time_point<motion_clock>;

  static const bool is_steady = false;

  static time_point now() noexcept {
    SimTime time;
    GetSimTime(&time);

    unsigned int seconds_since_epoch = time.Seconds;
    unsigned int microseconds_within_second = time.USec;

    std::chrono::seconds seconds_duration(seconds_since_epoch);
    std::chrono::microseconds microseconds_duration(microseconds_within_second);

    // Calculate the total duration
    std::chrono::microseconds total_duration = seconds_duration + microseconds_duration;

    return ans_motion_util::motion_clock::time_point(total_duration);
  }
};

My goal is of course, that all instances of std::this_thread::sleep_for() sleep with regard to the accelerated time GetSimTime provided via my speedy_clock. Is this doable or do I need to write my own version of sleep for?

Answer 1

I'm afraid you'll have to write a custom sleep function. std::this_thread::sleep_for sleeps on a std::chrono::duration. And std::chrono::duration is completely ignorant of the existence of clocks:

template <class Rep, class Period = ratio<1>>
class duration
{
    Rep count_;

public:
    duration() = default;
    // ...
};