AMQP monkey patch

gistfile1.txt

# This monkey patches tmm1's amqp gem to handle Basic Return

module AMQP
  class ConsumerHijacker
    attr_reader :header, :body
    
    def receive(header, body)
      @header, @body = header, body
    end
    
    def reset!
      receive(nil, nil)
    end
  end
  
  class Channel
    alias_method :old_process_frame, :process_frame

    def process_frame(frame)
      if frame.is_a?(Frame::Body) && @method.is_a?(Protocol::Basic::Return)
        @consumer_hijacker ||= ConsumerHijacker.new
        @consumer_hijacker.reset!
        actual_consumer = @consumer
        @consumer = @consumer_hijacker
        old_process_frame(frame)
        @consumer = actual_consumer
        if @consumer_hijacker.header && @consumer_hijacker.body
          header, body = @consumer_hijacker.header, @consumer_hijacker.body
          @consumer.receive(header, body) if @consumer
          @return_callback.call(Header.new(self, header), body) if @return_callback
        end
      else
        old_process_frame(frame)
      end
    end
    
    def on_return(&callback)
      @return_callback = callback
    end
  end
end