io.Copy and timeout

io.Copy is useful in passing date from Reader to Writer. However, io.Copy hides Read(), Write() method calls.

When we want to set timeout to TCP socket I/O, I found wrapping this with customized type is the straight forward way like this:

package main

import (
	"io"
	"log"
	"net"
	"syscall"
	"time"
)

type IdleTimeoutConn struct {
	Conn net.Conn
}

func (self IdleTimeoutConn) Read(buf []byte) (int, error) {
	self.Conn.SetDeadline(time.Now().Add(5 * time.Second))
	return self.Conn.Read(buf)
}

func (self IdleTimeoutConn) Write(buf []byte) (int, error) {
	self.Conn.SetDeadline(time.Now().Add(5 * time.Second))
	return self.Conn.Write(buf)
}

func main() {
	ln, err := net.Listen("tcp", ":7")
	if err != nil {
		panic(err)
	}
	for {
		con, err := ln.Accept()
		if err != nil {
			if eno, ok := err.(syscall.Errno); ok && eno.Temporary() {
				continue
			}
			panic(err)
		}
		go func() {
			tcon := IdleTimeoutConn{
				Conn: con,
			}
			log.Print(io.Copy(tcon, tcon))
		}()
	}
}