Specifically check for timeout error

Question

I use the following to check for timeouts when calling a webservice, but I would like to check specifically if there is a timeout error returned. How do I do that :S

I have this:

// Timeout type Timeout struct {     Connect   time.Duration     ReadWrite time.Duration }  // TimeoutDialer func TimeoutDialer(timeout *Timeout) func(net, addr string) (c net.Conn, err error) {     return func(netw, addr string) (net.Conn, error) {             conn, err := net.DialTimeout(netw, addr, timeout.Connect)         if err != nil {             return nil, err         }         conn.SetDeadline(time.Now().Add(timeout.ReadWrite))         return conn, nil     } }  // HttpClient func HttpClient(config Config) *http.Client {     to := &Timeout{         Connect:   time.Duration(config.MaxWait) * time.Second,         ReadWrite: time.Duration(config.MaxWait) * time.Second,     }      return &http.Client{         Transport: &http.Transport{             Dial: TimeoutDialer(to),         },     } } 

Answer 1

As of go1.6, all errors from timeouts should conform to net.Error with Timeout() set properly. All you need to check for is:

if err, ok := err.(net.Error); ok && err.Timeout() { 

---

In older versions, checking for timeout through the http package was more difficult.

• You can get a *net.OpError with Timeout() if you hit a Deadline set on the underlying connection.
• You can get a tlsHandshakeTimeoutError (which is obviously not exported) that implements the net.Error interface.
• You can get a url.Error, if there was a problem within the url package (timeout during initial connection)
• You can get an error with "use of closed network connection" if you hit a timeout set with http.Client.Timeout[go1.3+] (which calls Transport.CancelRequest). As of go1.5, this will have the Timeout property set correctly.

You could check for a net.Error with a type switch:

switch err := err.(type) { case net.Error:     if err.Timeout() {         fmt.Println("This was a net.Error with a Timeout")     } case *url.Error:     fmt.Println("This is a *url.Error")     if err, ok := err.Err.(net.Error); ok && err.Timeout() {         fmt.Println("and it was because of a timeout")     } } 

With go < 1.5 you will need to check the error string for an http.Client timeout:

if err != nil && strings.Contains(err.Error(), "use of closed network connection") {     fmt.Println("Could be from a Transport.CancelRequest") }