display percentages in a rake task

percentages_display

  def calculate_perc(i, total)
    (i * 100 / total).to_i
  end

  def rate_limit_1_perc?(perc, last_perc, last_updated)
    # Changes of at least 1% 
    # once every 20 seconds
    perc > last_perc && last_updated < Time.now.ago(20.seconds)
  end

  def rate_limit_5_perc?(perc, last_perc, last_updated)
    # Changes >5%
    # once every 10 seconds
    perc.divmod(5).first > last_perc.divmod(5).first && 
        last_updated < Time.now.ago(10.seconds)
  end

  def show_start_end_perc?(i, total)
    # Show 0% and 100%
    i == 1 || i == total
  end
  
  def main_loop
    i = 1
    last_perc ||= 0
    last_updated ||= Time.now
    total = e_batch.e_base_records.size
    
   array_of_records.each do |rec|
      if show_progress
        perc = calculate_perc(i, total)

        if rate_limit_1_perc?(perc, last_perc, last_updated) ||
           rate_limit_5_perc?(perc, last_perc, last_updated) ||
           show_start_end_perc?(i, total)

          print "#{perc}% "

          $stdout.flush
          last_updated = Time.now
        end
        i += 1
        last_perc = perc
      end
    end
  end