def get_queue(value)
      ms = (Time.now.to_f * 1000).to_i - value.to_i
      ms < 0 ? 0 : ms
    end
def get_queue(value)
      ms = (Time.now.to_f * 1000).to_i - value.to_i
      ms < 0 ? 0 : ms
    end
Calculates the difference, in milliseconds, between the
 HTTP_X_REQUEST_START time and the current time.

 @param [String] the timestamp from HTTP_X_REQUEST_START.
 @return [Integer] the queue time in milliseconds.