http trace

HTTP Request trace, timing and request’s information.
Timing include dns, connect, tls, first response byte and so on.

events:

• GetConn
• DNSStart
• DNSDone
• ConnectStart
• ConnectDone
• TLSHandshakeStart
• TLSHandshakeDone
• GotConn
• WroteHeaders
• WroteRequest
• GotFirstResponseByte

trace, ht := NewClientTrace()
ctx := context.Background()
ctx = httptrace.WithClientTrace(ctx, trace)
req, _ := http.NewRequest("GET", "https://www.baidu.com/", nil)
req = req.WithContext(ctx)
resp, _ := http.DefaultClient.Do(req)
ht.Finish()
stats := ht.Stats()
fmt.Println(stats)
fmt.Println(resp.Status)