Example of an auto-piplining HTTP client

auto_pipeline.rb

require "net/http/persistent"
require "net/http/pipeline"

class DeferredProxy < BasicObject
  def initialize(&generator)
    @generator = generator
  end

  def method_missing(*args, &block)
    @source ||= @generator.call
    @source.send(*args, &block)
  end
end

# Usage:
#   client = Client.new("http://www.apple.com")
# 
# queue up some requests:
#   a = client.get("/")
#   b = client.get("/mac/")
#   c = client.get("/ipad/")
# 
# requests aren't made untill one of the responses is actually used.
#   puts a.code
class Client
  def initialize(url)
    @uri = URI.parse(url)
    @http = Net::HTTP::Persistent.new(self.class.name)
    @requests = []
    @responses = {}
  end

  def get(path)
    request = Net::HTTP::Get.new(path, {})
    @requests << request
    DeferredProxy.new do
      do_requests unless @responses.key?(request)
      @responses.delete(request)
    end
  end

  private

  def do_requests
    requests = @requests.dup
    @responses.merge!(Hash[requests.zip(@http.pipeline(@uri, @requests))])
  end
end