quick hack to download some course materials

parallel_download.rb

require 'hpricot'
require 'open-uri'
require 'parallel'

overall_start_time = Time.now
uri = "http://www.stanford.edu/class/cs193p/cgi-bin/drupal/downloads-2010-fall"
puts "Downloading #{uri}"
doc = Hpricot(open(uri))

pdfs = doc/"//a[@href*=pdf]"

Dir.mkdir('download') unless File.directory?('download')
Dir.chdir('download')

Parallel.map(pdfs, :in_threads=>8) do |e|
  fileName = e.inner_html
  startTime = Time.now
  puts "Downloading #{fileName}"
	open(fileName, 'wb') do |file|
		file << open(e['href']).read
	end
	elapsedTime = Time.now - startTime
	puts "#{fileName} downloaded in #{elapsedTime} seconds"
end
puts "Finished in #{Time.now - overall_start_time}"