def is_update_free_time(bar_index)
    cache_key = "progress_bar_#{self.experiment_id}_#{bar_index}"

    bar_last_update = Rails.cache.read(cache_key)
    Rails.logger.debug("Bar last update - #{bar_last_update}")
    Rails.cache.write(cache_key, Time.now, :expires_in => 30) if bar_last_update.nil?

    not bar_last_update.nil?
  end