Add Keepalive ping/pong (#46)

moon/cfc_chat_transit/server/init.moon

@@ -22,6 +22,13 @@ hook.Add "Think", loadHook, ->
     with ChatTransit.WebSocket
         .reconnectTimerName = "CFC_ChatTransit_WebsocketReconnect"
 
+        .onMessage = (msg) =>
+            if msg ~= "keepalive"
+                logger\info "Received a not-keepalive message from the server:", msg
+                return
+
+            \write "keepalive"
+
         .onConnected = =>
             logger\info "Established websocket connection"
             timer.Remove .reconnectTimerName
@@ -76,6 +83,11 @@ ChatTransit.guard = (f, delay) -> (...) ->
 
     return nil
 
+hook.Add "ShutDown", "CFC_ChatTransit_WebsocketDisconnect", ->
+    logger\info "Gracefully closing websocket.."
+    ProtectedCall -> ChatTransit.WebSocket\closeNow!
+    return nil
+
 logger\info "Loading modules..."
 for f in *file.Find "cfc_chat_transit/server/modules/*.lua", "LUA"
     logger\info "Loading modules/#{f}"

web/discord_relay/relay.go

@@ -1,16 +1,32 @@
 package main
 
 import (
-	"github.com/gorilla/websocket"
 	"log"
 	"net/http"
+	"time"
+
+	"github.com/gorilla/websocket"
 )
 
 var upgrader = websocket.Upgrader{}
 
-func relay(w http.ResponseWriter, r *http.Request) {
-	// TODO: Prevent multiple clients here
+func keepAlive(c *websocket.Conn, r *http.Request) {
+	ctx := r.Context()
 
+	select {
+	case <-time.After(2 * time.Second):
+		err := c.WriteMessage(websocket.PingMessage, []byte("keepalive"))
+		if err != nil {
+			log.Print("Received an error when sending keepalive. Exiting keepalive loop")
+			return
+		}
+	case <-ctx.Done():
+		log.Print("Request context is done. Existing keepalive loop")
+		return
+	}
+}
+
+func relay(w http.ResponseWriter, r *http.Request) {
 	c, err := upgrader.Upgrade(w, r, nil)
 	if err != nil {
 		log.Print("upgrade:", err)
@@ -19,6 +35,8 @@ func relay(w http.ResponseWriter, r *http.Request) {
 
 	defer c.Close()
 
+	go keepAlive(c, r)
+
 	for {
 		_, message, err := c.ReadMessage()
 		if err != nil {