Ruby HTTP file download with progress measurement

download-progress.rb

require 'net/http'

def download(url)
  Thread.new do
    thread = Thread.current
    thread[:body] = []
    thread[:done] = 0
    
    url = URI(url)
    Net::HTTP.new(url.host, url.port).get2(url.path) do |res|
      length = thread[:length] = res.content_length

      res.read_body do |segment|
        thread[:body] << segment
        thread[:done] += segment.length
        thread[:progress] = thread[:done].fdiv(length)
      end
    end
  end
end

thread = download "http://mirror.pnl.gov/releases/10.04/ubuntu-10.04.3-desktop-i386.iso"
puts "%.2f%%" % (thread[:progress]*100) until thread.join(4)