sdlisten.go

package main

import (
	"flag"
	"fmt"
	"log"
	"net"
	"os"
	"os/signal"
	"time"
)

var (
	info_log  = log.New(os.Stdout, "i ", log.LstdFlags)
	error_log = log.New(os.Stderr, "e ", log.LstdFlags)
)

func bail(status int, t string, args ...interface{}) {
	if status == 0 {
		info_log.Printf(t, args...)
	} else {
		error_log.Printf(t, args...)
	}
	os.Exit(0)
}

var opts struct {
	port int
}

func handle(conn net.Conn) {
	for count := 0; count < 10000; count++ {
		fmt.Fprintln(conn, "hi. count: ", count)
		time.Sleep(1 * time.Second)
	}
}

func main() {
	flag.IntVar(&opts.port, "port", 9000, "the port on which we listen")
	flag.Parse()

	l, err := net.ListenTCP("tcp4", &net.TCPAddr{Port: opts.port})
	if err != nil {
		bail(1, "couldn't open port %d: %v", opts.port, err)
	}

	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt, os.Kill)
	go func() {
		<-c
		info_log.Printf("closing listener")
		l.Close()
	}()

	for {
		conn, err := l.Accept()
		if err != nil {
			error_log.Printf("unable to accept new connection: %v", err)
			break
		}
		go handle(conn)
	}

	<-c
	bail(0, "shutting down")
}