Ruby HTTP file download with progress measurement

download-progress.rb

require 'net/http'
require 'uri'

def download(url)
  Thread.new do
    thread = Thread.current
    body = thread[:body] = []
    
    url = URI.parse url
    Net::HTTP.new(url.host, url.port).request_get(url.path) do |response|
      length = thread[:length] = response['Content-Length'].to_i

      response.read_body do |fragment|
        body << fragment
        thread[:done] = (thread[:done] || 0) + fragment.length
        thread[:progress] = thread[:done].quo(length) * 100
      end
    end
  end
end

thread = download 'http://caesar.acc.umu.se/mirror/ubuntu-releases/10.04/ubuntu-10.04-desktop-i386.iso'
puts "%.2f%%" % thread[:progress].to_f until thread.join 1