add a IP addr in this error for locating issues faster?

[goith]

fasthttp/tcpdialer.go

Line 365 in 03813ae

var ErrDialTimeout = errors.New("dialing to the given TCP address timed out")

usually, dialing a host, that resovle to mullti ips. and If include the IP information in this ErrDialTimeout, we can know which server is the problem faster.

[erikdubbelboer]

The problem is that we can't really add it to the error as that would change the API. If we make the error dynamic doing err == fasthttp.ErrDialTimeout won't work anymore.

Anyone have any suggestions on how to put this in there?

[phuslu]

a possible path is

1. rewrite fasthttp.ErrDialTimeout to a struct, maybe DailTimeoutError which implement net.Error interface

// see https://golang.org/src/net/net.go?s=17034:17068#L539
type DailTimeoutError struct {
	Err  string
	Addr string
}

func (e *DailTimeoutError) Error() string {
	if e == nil {
		return "<nil>"
	}
	s := e.Err
	if e.Addr != "" {
		s = "dialing to the given TCP address " + e.Addr + ": " + s
	}
	return s
}

func (e *DailTimeoutError) Timeout() bool   { return true}
func (e *DailTimeoutError) Temporary() bool { return true}

var ErrDialTimeout = &DailTimeoutError{Err: "dialing to the given TCP address timed out"}

2. return "Timeout() bool" to true
3. encourage user use Timeout() bool or net.Error interface
4. finally, drop ErrDialTimeout at proper future.

[erikdubbelboer]

@phuslu that would still break for users who currently do err == fasthttp.ErrDialTimeout in their code.

[Fenny]

This would break the existing API design, but could be possible when Fasthttp moves to an organization github.com/fasthttp/fasthttp #684