don't add redundant IDs to batch timers, close data channel properly

frontend/ts/batch-timer.ts

@@ -10,10 +10,12 @@ export class BatchTimer {
   }
   
   public queue(id: string, timeout: number){
+    if (!this._batch.includes(id)) {
       this._timer = new Date().getTime() + timeout;
       this._batch.push(id);
       setTimeout(this.checkBatch.bind(this), timeout);
     }
+  }
   
   private checkBatch() {
     if ((new Date()).getTime() >= this._timer) {

server/server.go

@@ -98,6 +98,7 @@ func (self *BBSServer) subscribeHandler(w http.ResponseWriter, r *http.Request)
 
 			case <-ctx.Done():
 				fmt.Println("subscriber has disconnected")
+				close(s.data)
 				return //ctx.Err()
 			}
 		}
@@ -109,6 +110,8 @@ func (self *BBSServer) subscribeHandler(w http.ResponseWriter, r *http.Request)
 	// block on the data channel, serializing and passing the data to the subscriber
 	listen([]chan models.SocketData{s.data}, s.msgs)
 
+	fmt.Println("data listener is done!")
+
 	if errors.Is(err, context.Canceled) {
 		return
 	}