Resty Tracer

main.go

package main

import (
	"context"
	"crypto/tls"
	"fmt"
	"net/http/httptrace"
	"time"

	"gopkg.in/resty.v1"
)

type HTTPTracer struct {
	GetConn              time.Time
	GotConn              time.Time
	GotFirstResponseByte time.Time
	DNSStart             time.Time
	DNSDone              time.Time
	ConnectStart         time.Time
	ConnectDone          time.Time
	TLSHandshakeStart    time.Time
	TLSHandshakeDone     time.Time
}

func (t *HTTPTracer) Context() context.Context {
	return httptrace.WithClientTrace(
		context.Background(),
		&httptrace.ClientTrace{
			GetConn:  func(_ string) { t.GetConn = time.Now() },
			DNSStart: func(_ httptrace.DNSStartInfo) { t.DNSStart = time.Now() },
			DNSDone:  func(_ httptrace.DNSDoneInfo) { t.DNSDone = time.Now() },
			ConnectStart: func(_, _ string) {
				if t.DNSDone.IsZero() {
					t.DNSDone = time.Now()
				}
			},
			GotConn:              func(_ httptrace.GotConnInfo) { t.GotConn = time.Now() },
			GotFirstResponseByte: func() { t.GotFirstResponseByte = time.Now() },
			TLSHandshakeStart:    func() { t.TLSHandshakeStart = time.Now() },
			TLSHandshakeDone:     func(_ tls.ConnectionState, _ error) { t.TLSHandshakeDone = time.Now() },
		},
	)
}

func main() {
	tr := &HTTPTracer{}
	_, _ = resty.R().
		SetContext(tr.Context()).
		Get("http://httpbin.org/get")
	endTime := time.Now()

	if tr.DNSStart.IsZero() {
		tr.DNSStart = tr.GetConn
		tr.DNSDone = tr.GetConn
	}
	fmt.Println("DNS Lookup", tr.DNSDone.Sub(tr.DNSStart))
	fmt.Println("TCP Connection", tr.GotConn.Sub(tr.DNSDone))
	fmt.Println("Server Processing", tr.GotFirstResponseByte.Sub(tr.GotConn))
	fmt.Println("TLS Handshake", tr.TLSHandshakeDone.Sub(tr.TLSHandshakeStart))
	fmt.Println("Content Transfer", endTime.Sub(tr.GotFirstResponseByte))
	fmt.Println("Total Time", endTime.Sub(tr.GetConn))
}