gracefully handle SIGINT on a Go webserver

webserver.go

package main

import (
    "net"
    "log"
    "net/http"
    "io"
    "time"
    "os"
    "os/signal"
    "syscall"
    "fmt"
    "sync"
)

type Handler struct {
    net.Listener
    sync.WaitGroup
}

func (h *Handler)ServeHTTP(w http.ResponseWriter, r *http.Request) {
    h.Add(1)
    defer h.Done()
    time.Sleep(time.Duration(5e9))
    io.WriteString(w, "hey")
}

func main() {
    handler := new(Handler)
    var err error
    handler.Listener, err = net.Listen("tcp", ":8000")
    if err != nil {
        log.Fatal(err)
    }

    c := make(chan os.Signal)
    signal.Notify(c, syscall.SIGINT)
    go func(quit chan os.Signal) {
        <-quit
        fmt.Println("Received SIGINT")
        handler.Wait()
        handler.Close()
        os.Exit(0)
    }(c)

    if err := http.Serve(handler, handler); err != nil {
        log.Fatal(err)
    }
}