only after mutations

cmd/cart/main.go

@@ -117,17 +117,19 @@ func main() {
 	promotionService := promotions.NewPromotionService(nil)
 
 	reg := cart.NewCartMultationRegistry()
-	reg.RegisterProcessor(actor.NewMutationProcessor(func(g *cart.CartGrain) error {
+	reg.RegisterProcessor(
-		ctx := promotions.NewContextFromCart(g)
+		actor.NewMutationProcessor(func(g *cart.CartGrain) error {
-		_, actions := promotionService.EvaluateAll(promotionData.State.Promotions, ctx)
+			ctx := promotions.NewContextFromCart(g)
-		for _, action := range actions {
+			_, actions := promotionService.EvaluateAll(promotionData.State.Promotions, ctx)
-			log.Printf("apply: %V", action)
+			for _, action := range actions {
-		}
+				log.Printf("apply: %V", action)
-		return nil
+			}
-	}), actor.NewMutationProcessor(func(g *cart.CartGrain) error {
+			return nil
-		g.UpdateTotals()
+		}),
-		return nil
+		actor.NewMutationProcessor(func(g *cart.CartGrain) error {
-	}))
+			g.UpdateTotals()
+			return nil
+		}))
 	diskStorage := actor.NewDiskStorage[cart.CartGrain]("data", reg)
 	poolConfig := actor.GrainPoolConfig[cart.CartGrain]{
 		MutationRegistry: reg,

pkg/actor/mutation_registry.go

@@ -225,10 +225,12 @@ func (r *ProtoMutationRegistry) Apply(grain any, msg ...proto.Message) ([]ApplyR
 		results = append(results, ApplyResult{Error: err, Type: rt.Name(), Mutation: m})
 	}
 
-	for _, processor := range r.processors {
+	if len(results) > 0 {
-		err := processor.Process(grain)
+		for _, processor := range r.processors {
-		if err != nil {
+			err := processor.Process(grain)
-			return results, err
+			if err != nil {
+				return results, err
+			}
 		}
 	}
 	return results, nil