support multiple mutations

cmd/cart/pool-server.go

@@ -29,8 +29,8 @@ func NewPoolServer(pool actor.GrainPool[*CartGrain], pod_name string, klarnaClie
 	}
 }
 
-func (s *PoolServer) ApplyLocal(id CartId, mutation proto.Message) (*CartGrain, error) {
-	return s.Apply(uint64(id), mutation)
+func (s *PoolServer) ApplyLocal(id CartId, mutation ...proto.Message) (*CartGrain, error) {
+	return s.Apply(uint64(id), mutation...)
 }
 
 func (s *PoolServer) HandleGet(w http.ResponseWriter, r *http.Request, id CartId) error {
@@ -178,28 +178,30 @@ func (s *PoolServer) HandleSetCartItems(w http.ResponseWriter, r *http.Request,
 	if err != nil {
 		return err
 	}
-	reply, err := s.ApplyLocal(id, &messages.ClearCartRequest{})
-	if err != nil {
-		return err
-	}
+
+	msgs := make([]proto.Message, 0, len(setCartItems.Items)+1)
+	msgs = append(msgs, &messages.ClearCartRequest{})
 	wg := sync.WaitGroup{}
 	for _, item := range setCartItems.Items {
 		wg.Add(1)
 		go func(sku string, quantity int) {
+			defer wg.Done()
 			msg, err := GetItemAddMessage(sku, quantity, setCartItems.Country, nil)
 			if err != nil {
 				log.Printf("error adding item %s: %v", sku, err)
 				return
 			}
-			reply, err = s.ApplyLocal(id, msg)
-			if err != nil {
-				log.Printf("error applying message %v: %v", msg, err)
-				return
-			}
-			wg.Done()
+			msgs = append(msgs, msg)
+
 		}(item.Sku, item.Quantity)
 	}
+
 	wg.Wait()
+
+	reply, err := s.ApplyLocal(id, msgs...)
+	if err != nil {
+		return err
+	}
 	return s.WriteResult(w, reply)
 }