: time_source_(time_source), histogram_(histogram), start_(time_source.monotonicTime()) {

  ensureTimeHistogram(histogram);

}

std::chrono::milliseconds HistogramCompletableTimespanImpl::elapsed() const {

  return HistogramCompletableTimespanImpl::elapsedDuration<std::chrono::milliseconds>();

}

void HistogramCompletableTimespanImpl::complete() { histogram_.recordValue(tickCount()); }

void HistogramCompletableTimespanImpl::ensureTimeHistogram(const Histogram& histogram) const {

  switch (histogram.unit()) {

  case Histogram::Unit::Null:

  case Histogram::Unit::Microseconds:

  case Histogram::Unit::Milliseconds:

    return;

        false,

        fmt::format("Cannot create a timespan flushing the duration to histogram '{}' because "

                    "it does not measure time. This is a programming error, either pass a "

                    "histogram measuring time or fix the unit of the passed histogram.",

                    histogram.name()));

  }

}

uint64_t HistogramCompletableTimespanImpl::tickCount() const {

  switch (histogram_.unit()) {

  case Histogram::Unit::Null:

    return 0;

  case Histogram::Unit::Microseconds:

    return HistogramCompletableTimespanImpl::elapsedDuration<std::chrono::microseconds>().count();

  case Histogram::Unit::Milliseconds:

    return HistogramCompletableTimespanImpl::elapsedDuration<std::chrono::milliseconds>().count();

  }