Go bounded network listener.

boudconn.go

package main

import (
	"fmt"
	"log"
	"net"
	"net/http"
	"time"
)

func NewBoundListener(maxActive int, l net.Listener) net.Listener {
	return &boundListener{l, make(chan bool, maxActive)}
}

type boundListener struct {
	net.Listener
	active chan bool
}

type boundConn struct {
	net.Conn
	active chan bool
}

func (l *boundListener) Accept() (net.Conn, error) {
	l.active <- true
	c, err := l.Listener.Accept()
	if err != nil {
		<-l.active
	}
	return &boundConn{c, l.active}, err
}

func (l *boundConn) Close() error {
	err := l.Conn.Close()
	<-l.active
	return err
}

func main() {
	l, err := net.Listen("tcp", "127.0.0.1:8080")
	if err != nil {
		log.Fatal(err)
	}
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		log.Printf("Sleeping...")
		before := time.Now()
		time.Sleep(5 * time.Second)
		log.Printf("Waking up!")
		fmt.Fprintf(w, "Slept for %d seconds.", time.Now().Sub(before)/time.Second)
	})
	http.Serve(NewBoundListener(2, l), http.DefaultServeMux)
}