ox-builder.rb

#!/usr/bin/env ruby

require 'ox'
require 'benchmark'
require 'builder'

NO_SUCH_KEY_CODE    = 'NoSuchKey'.freeze
NO_SUCH_KEY_MESSAGE = 'The specified key does not exist.'.freeze

@code    = NO_SUCH_KEY_CODE
@message = NO_SUCH_KEY_MESSAGE

def builder(indent = 2, params ={})
  xml = Builder::XmlMarkup.new(:indent => indent);
  xml.instruct! :xml, :version=>"1.0", :encoding=>"UTF-8"
  xml.Error do
    xml.Code @code
    xml.Message @message
    if @bucket
      xml.Bucket @bucket
    end
    xml.RequestId params['action_dispatch.request_id']
    xml.Resource params['path_info']
    xml.HostId params['server_name']
  end
  xml.target!
end

def ox(indent = 2, params={})
  Ox.default_options = { indent: indent, with_xml: true }
  doc = ::Ox::Document.new(:version => '1.0', :encoding => 'UTF-8')
  error = Ox::Element.new('Error')
  doc << error

  code = Ox::Element.new('Code')
  code << @code
  error << code

  if @bucket
    bucket = Ox::Element.new('Bucket')
    bucket << @bucket
    error << bucket
  end

  message = Ox::Element.new('Message')
  message << @message
  error << message

  request_id = Ox::Element.new('RequestId')
  if val = params['action_dispatch.request_id']
    request_id << val
  end
  error << request_id

  resource = Ox::Element.new('Resource')
  resource << params['path_info']
  error << resource

  host_id = Ox::Element.new('HostId')
  host_id << params['server_name']
  error << host_id
  Ox.dump(doc)
end

params = {
  'path_info'   => '/anonymous',
  'server_name' => 'example.org',
}

Benchmark.bm(20) do |x|
  x.report('Builder  indent=0') { 100000.times { builder(0, params) } }
  x.report('Ox       indent=0') { 100000.times { ox(-1, params) } }
end