Chore: Compress websocket messages once per broadcast to improve performance (#695)

server/websockets/client.go

@@ -47,7 +47,7 @@ type Client struct {
 	conn *websocket.Conn
 
 	// Buffered channel of outbound messages.
-	send chan []byte
+	send chan *websocket.PreparedMessage
 }
 
 // ReadPump is used here solely to monitor the connection, not to actually receive messages.
@@ -90,7 +90,7 @@ func (c *Client) writePump() {
 				return
 			}
 
-			if err := c.conn.WriteMessage(websocket.TextMessage, message); err != nil {
+			if err := c.conn.WritePreparedMessage(message); err != nil {
 				return
 			}
 		case <-ticker.C:
@@ -124,7 +124,7 @@ func ServeWs(hub *Hub, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	client := &Client{hub: hub, conn: conn, send: make(chan []byte, 256)}
+	client := &Client{hub: hub, conn: conn, send: make(chan *websocket.PreparedMessage, 256)}
 	client.hub.register <- client
 
 	// Allow collection of memory referenced by the caller by doing all work in new goroutines.

server/websockets/hub.go

@@ -6,6 +6,7 @@ import (
 	"sync/atomic"
 
 	"github.com/axllent/mailpit/internal/logger"
+	"github.com/gorilla/websocket"
 )
 
 // Hub maintains the set of active clients and broadcasts messages to the
@@ -61,9 +62,14 @@ func (h *Hub) Run() {
 				h.clientCount.Add(-1)
 			}
 		case message := <-h.Broadcast:
+			prepared, err := websocket.NewPreparedMessage(websocket.TextMessage, message)
+			if err != nil {
+				logger.Log().Errorf("[websocket] error preparing message: %s", err.Error())
+				continue
+			}
 			for client := range h.Clients {
 				select {
-				case client.send <- message:
+				case client.send <- prepared:
 				default:
 					close(client.send)
 					delete(h.Clients, client)