A better progress meter for your (Rails) scripts

As a follow-up to my post a couple weeks back on putting a progress meter in your long-running migrations, I've whipped up a more helpful and re-usable tool.

I've called it simply "Progress" and here it is in its entirety:

class Progress
  require 'action_view/helpers/date_helper'
  include ActionView::Helpers::DateHelper
  
  def initialize(total, interval = 10)
    @total = total
    @interval = interval
    @count = 0
    @start = Time.now
  end
  
  def tick
    @count += 1
    if 0 == @count % @interval
      sofar = Time.now
      elapsed = sofar - @start
      puts "been running for #{distance_of_time_in_words(@start, sofar)}"
      rate = elapsed / @count
      puts "at a rate of #{distance_of_time_in_words(sofar, (sofar - rate), true)} per item"
      finish = sofar + ((@total * rate) - elapsed)
      puts "should finish around #{distance_of_time_in_words(sofar, finish)}"
    end
  end
end

Usage is pretty simple. Here's an (slightly-abridged) example from a Rake task I wrote to clean out bad references to removed YouTube videos:

namespace :videos do
  desc "Remove videos from SpumCo if YouTube also removed them"
  task :purge => :environment do
    videos = Video.find(:all, :order => 'created_at asc')
    progress = Progress.new(videos.size)
    videos.each do |video|
      progress.tick
      video.destroy unless video.still_on_youtube?        
    end
  end
end

And what you see in the console as the script runs is periodic updates like so:

been running for less than a minute
at a rate of less than 5 seconds per item
should finish around 14 minutes