Rails output compress plugin

source code from: http://blog.craz8.com/files/compress.rb

require 'stringio'
require 'zlib'

class OutputCompressionFilter

  def self.filter(controller)
    return if controller.response.headers['Content-Encoding'] || controller.request.env['HTTP_ACCEPT_ENCODING'].nil?
    begin
      controller.request.env['HTTP_ACCEPT_ENCODING'].split(/\s*,\s*/).each do |encoding|
        # TODO: use "q" values to determine user agent encoding preferences
        case encoding
          when /\Agzip\b/
            StringIO.open('', 'w') do |strio|
              begin
                gz = Zlib::GzipWriter.new(strio)
                gz.write(controller.response.body)
                controller.response.body = strio.string
              ensure
                gz.close if gz
              end
            end
          when /\Adeflate\b/
            controller.response.body = Zlib::Deflate.deflate(controller.response.body, Zlib::BEST_COMPRESSION)
          when /\Aidentity\b/
            # do nothing for identity
          else
            next # the encoding is not supported, try the next one
        end
        controller.logger.info "Response body was encoded with #{encoding}" 
        controller.response.headers['Content-Encoding'] = encoding
        break    # the encoding is supported, stop
      end
    end
    controller.response.headers['Content-Length'] = controller.response.body.length
    if controller.response.headers['Vary'] != '*'
      controller.response.headers['Vary'] = 
        controller.response.headers['Vary'].to_s.split(',').push('Accept-Encoding').uniq.join(',')
    end
  end

end