graceful. not even mad

src/34-embedding.go

@@ -49,3 +49,7 @@ func main() {
 	}
 	fmt.Println(area)
 }
+
+// == todo
+// is this named wrong?
+// note about embedding access

src/xx-http-server-graceful-shutdown.go

@@ -0,0 +1,86 @@
+package main
+
+import ("net"; "net/http"; "time"; "os"; "os/signal"; "syscall"; "fmt"; "sync/atomic")
+
+func slow(res http.ResponseWriter, req *http.Request) {
+	fmt.Println("respond at=start")
+	time.Sleep(time.Second * 5)
+	res.Header().Set("Content-Type", "text/plain")
+	fmt.Fprintln(res, "Finally.")
+	fmt.Println("respond at=finish")
+}
+
+var connCount int64 = 0
+
+type watchedConn struct {
+	net.Conn
+}
+
+func (w *watchedConn) Close() error {
+	atomic.AddInt64(&connCount, -1)
+ 	return w.Conn.Close()
+}
+
+type watchedListener struct {
+	net.Listener
+}
+
+func (l *watchedListener) Accept() (net.Conn, error) {
+	conn, err := l.Listener.Accept()
+	if err != nil {
+		return nil, err
+	}
+	atomic.AddInt64(&connCount, 1)
+	return &watchedConn{Conn: conn}, nil
+}
+
+func main() {
+	stop := make(chan bool, 1)
+	sig := make(chan os.Signal, 1)
+	
+	server := &http.Server{Handler: http.HandlerFunc(slow)}
+	fmt.Println("listen at=start")
+	listener, listenErr := net.Listen("tcp", ":5000")
+	if listenErr != nil { panic(listenErr) }
+	wListener := &watchedListener{Listener: listener}
+	fmt.Println("listen at=finish")
+
+	go func() {
+		<-stop
+		fmt.Println("close at=start")
+		closeErr := wListener.Close()
+		if closeErr != nil { panic(closeErr) }
+		fmt.Println("close at=finish")
+	}()
+
+	go func() {
+		signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
+		fmt.Println("trap at=start")
+		<- sig
+		stop <- true
+		fmt.Println("trap at=finish")
+	}()
+
+	fmt.Println("serve at=start")
+	server.Serve(wListener)	
+	fmt.Println("serve at=finish")
+	for {
+		connCountCurrent := atomic.LoadInt64(&connCount)
+		if connCountCurrent > 0 {
+			fmt.Println("wait at=pending remaining=", connCountCurrent)
+			time.Sleep(time.Second)
+		} else {
+			fmt.Println("wait at=finish remaining=", connCountCurrent)
+			return
+		}
+	}
+}
+
+// == running
+// $ cd src
+// $ go build xx-http-server-graceful-shutdown.go
+// $ ./xx-http-server-graceful-shutdown
+//
+// $ curl -i http://127.0.0.1:5000/
+//
+// ^C