class FrequencyLoop
  def initialize(@frequency : Time::Span)
    @sleep = [] of Time::Span
    @span = [] of Time::Span
  end

  getter :sleep, :frequency, :span

  ZERO = Time::Span.zero

  def loop(max_tick : Int = UInt64::MAX, &)
    i = 0u64
    t0 = Time.utc
    while max_tick > i
      yield i
      t1 = Time.utc
      span = (t1 - t0)
      i += 1
      sleep_span = (@frequency * i) - span
      @sleep << sleep_span
      @span << span
      sleep(sleep_span) if sleep_span > ZERO
    end
  end
end