MM-34389: Reliable websockets: First commit (#17297)

* MM-34389: Reliable websockets: First commit

This is the first commit which makes some basic changes
to get it ready for the actual implementation.

Changes include:
- A config field to conditionally enable it.
- Refactoring the WriteMessage along with setting the deadline
to a separate method.

The basic idea is that the client sends the connection_id
and sequence_number either during the handshake (via query params),
or during challenge_auth (via added parameters in the map).

If the conn_id is empty, then we create a new one and set it.
Otherwise, we get the queues from a connection manager (TBD)
and attach them to WebConn.

```release-note
NONE
```

https://mattermost.atlassian.net/browse/MM-34389

* Incorporate review comments

* Trigger CI

* removing telemetry

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/web_conn.go

@@ -49,6 +49,7 @@ type WebConn struct {
 	send                      chan model.WebSocketMessage
 	sessionToken              atomic.Value
 	session                   atomic.Value
+	connectionID              atomic.Value
 	endWritePump              chan struct{}
 	pumpFinished              chan struct{}
 }
@@ -118,6 +119,11 @@ func (wc *WebConn) SetSessionToken(v string) {
 	wc.sessionToken.Store(v)
 }
 
+// SetConnectionID sets the connection id of the connection.
+func (wc *WebConn) SetConnectionID(id string) {
+	wc.connectionID.Store(id)
+}
+
 // GetSession returns the session of the connection.
 func (wc *WebConn) GetSession() *model.Session {
 	return wc.session.Load().(*model.Session)
@@ -147,6 +153,12 @@ func (wc *WebConn) Pump() {
 	wc.App.HubUnregister(wc)
 	close(wc.pumpFinished)
 
+	// TODO:
+	// Check if the channel is closed or not,
+	// if closed, then remove the entry from conn manager
+	// else
+	// take both channels, and store them in connection manager.
+
 	defer ReturnSessionToPool(wc.GetSession())
 }
 
@@ -195,8 +207,7 @@ func (wc *WebConn) writePump() {
 		select {
 		case msg, ok := <-wc.send:
 			if !ok {
-				wc.WebSocket.SetWriteDeadline(time.Now().Add(writeWaitTime))
-				wc.WebSocket.WriteMessage(websocket.CloseMessage, []byte{})
+				wc.writeMessage(websocket.CloseMessage, []byte{})
 				return
 			}
 
@@ -250,18 +261,18 @@ func (wc *WebConn) writePump() {
 				mlog.Warn("websocket.full", logData...)
 			}
 
-			wc.WebSocket.SetWriteDeadline(time.Now().Add(writeWaitTime))
-			if err := wc.WebSocket.WriteMessage(websocket.TextMessage, buf.Bytes()); err != nil {
+			if err := wc.writeMessage(websocket.TextMessage, buf.Bytes()); err != nil {
 				wc.logSocketErr("websocket.send", err)
 				return
 			}
 
+			// TODO: move to dead queue
+
 			if wc.App.Metrics() != nil {
 				wc.App.Metrics().IncrementWebSocketBroadcast(msg.EventType())
 			}
 		case <-ticker.C:
-			wc.WebSocket.SetWriteDeadline(time.Now().Add(writeWaitTime))
-			if err := wc.WebSocket.WriteMessage(websocket.PingMessage, []byte{}); err != nil {
+			if err := wc.writeMessage(websocket.PingMessage, []byte{}); err != nil {
 				wc.logSocketErr("websocket.ticker", err)
 				return
 			}
@@ -279,6 +290,13 @@ func (wc *WebConn) writePump() {
 	}
 }
 
+// writeMessage is a helper utility that wraps the write to the socket
+// along with setting the write deadline.
+func (wc *WebConn) writeMessage(msgType int, data []byte) error {
+	wc.WebSocket.SetWriteDeadline(time.Now().Add(writeWaitTime))
+	return wc.WebSocket.WriteMessage(msgType, data)
+}
+
 // InvalidateCache resets all internal data of the WebConn.
 func (wc *WebConn) InvalidateCache() {
 	wc.allChannelMembers = nil
@@ -318,7 +336,11 @@ func (wc *WebConn) IsAuthenticated() bool {
 
 func (wc *WebConn) createHelloMessage() *model.WebSocketEvent {
 	msg := model.NewWebSocketEvent(model.WEBSOCKET_EVENT_HELLO, "", "", wc.UserId, nil)
-	msg.Add("server_version", fmt.Sprintf("%v.%v.%v.%v", model.CurrentVersion, model.BuildNumber, wc.App.ClientConfigHash(), wc.App.Srv().License() != nil))
+	msg.Add("server_version", fmt.Sprintf("%v.%v.%v.%v", model.CurrentVersion,
+		model.BuildNumber,
+		wc.App.ClientConfigHash(),
+		wc.App.Srv().License() != nil))
+	msg.Add("connection_id", wc.connectionID.Load())
 	return msg
 }
 

app/websocket_router.go

@@ -55,11 +55,12 @@ func (wr *WebSocketRouter) ServeWebSocket(conn *WebConn, r *model.WebSocketReque
 			conn.WebSocket.Close()
 			return
 		}
-
 		conn.SetSession(session)
 		conn.SetSessionToken(session.Token)
 		conn.UserId = session.UserId
 
+		// TODO: Same logic to reconnect queue as api4/websocket.go
+
 		wr.app.HubRegister(conn)
 
 		wr.app.Srv().Go(func() {