[TOC] ## 語法 可追蹤的函數 ``` type ClientTrace struct { GetConn func(hostPort string) GotConn func(GotConnInfo) PutIdleConn func(err error) GotFirstResponseByte func() Got100Continue func() DNSStart func(DNSStartInfo) DNSDone func(DNSDoneInfo) ConnectStart func(network, addr string) ConnectDone func(network, addr string, err error) TLSHandshakeStart func() TLSHandshakeDone func(tls.ConnectionState, error) WroteHeaders func() Wait100Continue func() WroteRequest func(WroteRequestInfo) } ``` ## 實例 ### 設置監聽函數 ``` req, _ := http.NewRequest("GET", "http://example.com", nil) trace := &httptrace.ClientTrace{ GotConn: func(connInfo httptrace.GotConnInfo) { fmt.Printf("Got Conn: %+v\n", connInfo) }, DNSStart: func(info httptrace.DNSStartInfo) { fmt.Printf("DNSStart %+v\n", info) }, DNSDone: func(dnsInfo httptrace.DNSDoneInfo) { fmt.Printf("DNS Info: %+v\n", dnsInfo) }, ConnectStart: func(network, addr string) { fmt.Printf("connectStart %+v%+v\n", network, addr) }, } req = req.WithContext(httptrace.WithClientTrace(req.Context(), trace)) res, err := http.DefaultClient.Do(req) if err != nil { log.Fatal(err) } fmt.Printf("%+v\n", res.Status) ```