func setupReqStatsUpdate(req *http.Request) (*http.Request, func()) {
	var dialStart, dialEnd int64
	start := time.Now()
	trace := &httptrace.ClientTrace{
		GotFirstResponseByte: func() {
			atomic.AddUint64(&globalStats.tcpTimeForFirstByteTotalDur, uint64(time.Since(start)))
		},
		ConnectStart: func(network, addr string) {
			atomic.StoreInt64(&dialStart, time.Now().UnixNano())
		},
		ConnectDone: func(network, addr string, err error) {