initial work

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

app/echo.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"net/http"
+
+	"github.com/gorilla/websocket"
+)
+
+var (
+	wsClients = make(map[*websocket.Conn]struct{})
+
+	ws = struct {
+		Count chan int
+		Send  chan []byte
+		Add   chan *websocket.Conn
+	}{
+		Count: make(chan int, 100),
+		Send:  make(chan []byte, 100),
+		Add:   make(chan *websocket.Conn, 100),
+	}
+)
+
+func broadcast() {
+	for {
+		select {
+		case conn := <-ws.Add:
+			wsClients[conn] = struct{}{}
+
+		case <-ws.Count:
+			ws.Count <- len(wsClients)
+
+		case message := <-ws.Send:
+			for conn := range wsClients {
+				if err := conn.WriteMessage(1, message); err != nil {
+					conn.Close()
+					delete(wsClients, conn)
+				}
+			}
+		}
+	}
+}
+
+func wsHandler(w http.ResponseWriter, r *http.Request) {
+	conn, err := websocket.Upgrade(w, r, w.Header(), 1024, 1024)
+	if err != nil {
+		return
+	}
+	ws.Add <- conn
+}