safe truncation

cart-grain.go

@@ -238,7 +238,6 @@ func (c *CartGrain) HandleMessage(message *Message, isReplay bool) (*CallResult,
 				if item.Id == int(msg.Id) {
 					if item.Quantity <= int(msg.Quantity) {
 						c.Items = append(c.Items[:i], c.Items[i+1:]...)
-
 					} else {
 						item.Quantity -= int(msg.Quantity)
 					}
@@ -253,13 +252,15 @@ func (c *CartGrain) HandleMessage(message *Message, isReplay bool) (*CallResult,
 		if !ok {
 			err = fmt.Errorf("expected RemoveItem")
 		} else {
-			for i, item := range c.Items {
+			items := make([]*CartItem, 0, len(c.Items))
+			for _, item := range c.Items {
 				if item.Id == int(msg.Id) {
 					c.TotalPrice -= item.Price * int64(item.Quantity)
-					c.Items = append(c.Items[:i], c.Items[i+1:]...)
-					break
+				} else {
+					items = append(items, item)
 				}
 			}
+			c.Items = items
 		}
 	case SetDeliveryType:
 		msg, ok := message.Content.(*messages.SetDelivery)