asciinema.org/app/services/view_counter.rb

class ViewCounter

  def increment(asciicast, storage)
    key = :"asciicast_#{asciicast.id}_viewed"
    return if storage[key]

    Asciicast.increment_counter(:views_count, asciicast.id)
    asciicast.reload
    storage[key] = '1'
  end

end