first servicable server

wsconn.go

@@ -0,0 +1,125 @@
+// Slightly modified from The Gorilla Websocket Authors.
+//
+// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package kubelwagen
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/gorilla/websocket"
+	"github.com/sirupsen/logrus"
+)
+
+const (
+	// Time allowed to write a message to the peer.
+	writeWait = 10 * time.Second
+
+	// Time allowed to read the next pong message from the peer.
+	pongWait = 60 * time.Second
+
+	// Send pings to peer with this period. Must be less than pongWait.
+	pingPeriod = (pongWait * 9) / 10
+)
+
+var upgrader = websocket.Upgrader{
+	ReadBufferSize:  1024,
+	WriteBufferSize: 1024,
+}
+
+// Client is a middleman between the websocket connection and the hub.
+type WSConn struct {
+	hub *Hub
+
+	// The websocket connection.
+	conn *websocket.Conn
+
+	// Buffered channel of outbound messages.
+	send chan Request
+}
+
+// readPump pumps messages from the websocket connection to the hub.
+//
+// The application runs readPump in a per-connection goroutine. The application
+// ensures that there is at most one reader on a connection by executing all
+// reads from this goroutine.
+func (c *WSConn) readPump() {
+	defer func() {
+		c.hub.Lock()
+		defer c.hub.Unlock()
+		c.hub.conn = nil
+		c.conn.Close()
+	}()
+	c.conn.SetReadDeadline(time.Now().Add(pongWait))
+	c.conn.SetPongHandler(func(string) error { c.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
+	for {
+		var resp Response
+		err := c.conn.ReadJSON(&resp)
+		if err != nil {
+			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
+				logrus.Printf("error: %v", err)
+			}
+			break
+		}
+		c.hub.responses <- resp
+	}
+}
+
+// writePump pumps messages from the hub to the websocket connection.
+//
+// A goroutine running writePump is started for each connection. The
+// application ensures that there is at most one writer to a connection by
+// executing all writes from this goroutine.
+func (c *WSConn) writePump() {
+	ticker := time.NewTicker(pingPeriod)
+	defer func() {
+		ticker.Stop()
+		c.conn.Close()
+	}()
+	for {
+		select {
+		case message, ok := <-c.send:
+			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
+			if !ok {
+				// The hub closed the channel.
+				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
+				return
+			}
+
+			err := c.conn.WriteJSON(message)
+			if err != nil {
+				return
+			}
+
+		case <-ticker.C:
+			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
+			if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
+				return
+			}
+		}
+	}
+}
+
+func serveWs(hub *Hub, w http.ResponseWriter, r *http.Request) {
+	hub.Lock()
+	defer hub.Unlock()
+	if hub.conn != nil {
+		w.WriteHeader(400)
+		w.Write([]byte("Client already connected"))
+	}
+	conn, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		logrus.Println(err)
+		return
+	}
+	client := &WSConn{hub: hub, conn: conn, send: make(chan Request, 256)}
+	hub.conn = client
+
+	// Allow collection of memory referenced by the caller by doing all work in
+	// new goroutines.
+	go client.writePump()
+	go client.readPump()
+}