From 7eb000fd1777fd169655a9fe20a3b26acf05fb99 Mon Sep 17 00:00:00 2001
From: matst80 <mats.tornberg@gmail.com>
Date: Mon, 20 Oct 2025 21:09:45 +0200
Subject: [PATCH] only after mutations

---
 cmd/cart/main.go               | 24 +++++++++++++-----------
 pkg/actor/mutation_registry.go | 10 ++++++----
 2 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/cmd/cart/main.go b/cmd/cart/main.go
index 6c3a1e7..0e48304 100644
--- a/cmd/cart/main.go
+++ b/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 {
-		ctx := promotions.NewContextFromCart(g)
-		_, actions := promotionService.EvaluateAll(promotionData.State.Promotions, ctx)
-		for _, action := range actions {
-			log.Printf("apply: %V", action)
-		}
-		return nil
-	}), actor.NewMutationProcessor(func(g *cart.CartGrain) error {
-		g.UpdateTotals()
-		return nil
-	}))
+	reg.RegisterProcessor(
+		actor.NewMutationProcessor(func(g *cart.CartGrain) error {
+			ctx := promotions.NewContextFromCart(g)
+			_, actions := promotionService.EvaluateAll(promotionData.State.Promotions, ctx)
+			for _, action := range actions {
+				log.Printf("apply: %V", action)
+			}
+			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,
diff --git a/pkg/actor/mutation_registry.go b/pkg/actor/mutation_registry.go
index ca7d774..b76e693 100644
--- a/pkg/actor/mutation_registry.go
+++ b/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 {
-		err := processor.Process(grain)
-		if err != nil {
-			return results, err
+	if len(results) > 0 {
+		for _, processor := range r.processors {
+			err := processor.Process(grain)
+			if err != nil {
+				return results, err
+			}
 		}
 	}
 	return results, nil