Go语言 如果实现http重连？

怎样做到每次使用一个连接发送和接收前就设置超时呢？我想了个办法是在Dial回调返回自己包装过的TimeoutConn，间接的调用真实的Conn，这样就可以再每次Read和Write之前设置超时时间了。

以下是修改后的实验代码：

//// How to set timeout for http.Get() in golang//package mainimport (    "io"    "io/ioutil"    "log"    "net"    "net/http"    "sync"    "time")type TimeoutConn struct {    conn    net.Conn    timeout time.Duration}func NewTimeoutConn(conn net.Conn, timeout time.Duration) *TimeoutConn {    return &TimeoutConn{        conn:    conn,        timeout: timeout,    }}func (c *TimeoutConn) Read(b []byte) (n int, err error) {    c.SetReadDeadline(time.Now().Add(c.timeout))    return c.conn.Read(b)}func (c *TimeoutConn) Write(b []byte) (n int, err error) {    c.SetWriteDeadline(time.Now().Add(c.timeout))    return c.conn.Write(b)}func (c *TimeoutConn) Close() error {    return c.conn.Close()}func (c *TimeoutConn) LocalAddr() net.Addr {    return c.conn.LocalAddr()}func (c *TimeoutConn) RemoteAddr() net.Addr {    return c.conn.RemoteAddr()}func (c *TimeoutConn) SetDeadline(t time.Time) error {    return c.conn.SetDeadline(t)}func (c *TimeoutConn) SetReadDeadline(t time.Time) error {    return c.conn.SetReadDeadline(t)}func (c *TimeoutConn) SetWriteDeadline(t time.Time) error {    return c.conn.SetWriteDeadline(t)}func main() {    client := &http.Client{        Transport: &http.Transport{            Dial: func(netw, addr string) (net.Conn, error) {                log.Printf("dial to %s://%s", netw, addr)                conn, err := net.DialTimeout(netw, addr, time.Second*2)                if err != nil {                    return nil, err                }                return NewTimeoutConn(conn, time.Second*2), nil            },            ResponseHeaderTimeout: time.Second * 2,        },    }    addr := StartTestServer()    SendTestRequest(client, "1st", addr, "normal")    SendTestRequest(client, "2st", addr, "normal")    SendTestRequest(client, "3st", addr, "timeout")    SendTestRequest(client, "4st", addr, "normal")    time.Sleep(time.Second * 3)    SendTestRequest(client, "5st", addr, "normal")}func StartTestServer() string {    listener, err := net.Listen("tcp", ":0")    if err != nil {        log.Fatalf("failed to listen - %s", err.Error())    }    wg := new(sync.WaitGroup)    wg.Add(1)    go func() {        http.HandleFunc("/normal", func(w http.ResponseWriter, req *http.Request) {            time.Sleep(1000 * time.Millisecond)            io.WriteString(w, "ok")        })        http.HandleFunc("/timeout", func(w http.ResponseWriter, req *http.Request) {            time.Sleep(2500 * time.Millisecond)            io.WriteString(w, "ok")        })        wg.Done()        err = http.Serve(listener, nil)        if err != nil {            log.Fatalf("failed to start HTTP server - %s", err.Error())        }    }()    wg.Wait()    log.Printf("start http server at http://%s/", listener.Addr())    return listener.Addr().String()}func SendTestRequest(client *http.Client, id, addr, path string) {    req, err := http.NewRequest("GET", "http://"+addr+"/"+path, nil)    if err != nil {        log.Fatalf("new request failed - %s", err)    }    req.Header.Add("Connection", "keep-alive")    switch path {    case "normal":        if resp, err := client.Do(req); err != nil {            log.Fatalf("%s request failed - %s", id, err)        } else {            result, err2 := ioutil.ReadAll(resp.Body)            if err2 != nil {                log.Fatalf("%s response read failed - %s", id, err2)            }            resp.Body.Close()            log.Printf("%s request - %s", id, result)        }    case "timeout":        if _, err := client.Do(req); err == nil {            log.Fatalf("%s request not timeout", id)        } else {            log.Printf("%s request - %s", id, err)        }    }}