snapshot of https://github.com/ThreeDotsLabs/watermill.git (master, 2026-09-15; blobs > 131072B omitted)

_examples/real-world-examples/delayed-requeue/main.go

@@ -0,0 +1,197 @@
+package main
+
+import (
+	"context"
+	stdSQL "database/sql"
+	"fmt"
+	"math/rand"
+	"time"
+
+	"github.com/ThreeDotsLabs/watermill/message/router/middleware"
+
+	"github.com/brianvoe/gofakeit/v6"
+	_ "github.com/lib/pq"
+	"github.com/redis/go-redis/v9"
+
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill-redisstream/pkg/redisstream"
+	"github.com/ThreeDotsLabs/watermill-sql/v4/pkg/sql"
+	"github.com/ThreeDotsLabs/watermill/components/cqrs"
+	"github.com/ThreeDotsLabs/watermill/message"
+)
+
+func main() {
+	db, err := stdSQL.Open("postgres", "postgres://watermill:password@postgres:5432/watermill?sslmode=disable")
+	if err != nil {
+		panic(err)
+	}
+
+	logger := watermill.NewStdLogger(false, false)
+
+	redisClient := redis.NewClient(&redis.Options{Addr: "redis:6379"})
+
+	redisPublisher, err := redisstream.NewPublisher(redisstream.PublisherConfig{
+		Client: redisClient,
+	}, logger)
+	if err != nil {
+		panic(err)
+	}
+
+	delayedRequeuer, err := sql.NewPostgreSQLDelayedRequeuer(sql.DelayedRequeuerConfig{
+		DB:        sql.BeginnerFromStdSQL(db),
+		Publisher: redisPublisher,
+		DelayOnError: &middleware.DelayOnError{
+			InitialInterval: 10 * time.Second,
+			MaxInterval:     3 * time.Minute,
+			Multiplier:      2,
+		},
+		Logger: logger,
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	marshaler := cqrs.JSONMarshaler{
+		GenerateName: cqrs.StructName,
+	}
+
+	eventBus, err := cqrs.NewEventBusWithConfig(redisPublisher, cqrs.EventBusConfig{
+		GeneratePublishTopic: func(params cqrs.GenerateEventPublishTopicParams) (string, error) {
+			return params.EventName, nil
+		},
+		Marshaler: marshaler,
+		Logger:    logger,
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	router := message.NewDefaultRouter(logger)
+	router.AddMiddleware(delayedRequeuer.Middleware()...)
+
+	eventProcessor, err := cqrs.NewEventProcessorWithConfig(router, cqrs.EventProcessorConfig{
+		GenerateSubscribeTopic: func(params cqrs.EventProcessorGenerateSubscribeTopicParams) (string, error) {
+			return params.EventName, nil
+		},
+		SubscriberConstructor: func(params cqrs.EventProcessorSubscriberConstructorParams) (message.Subscriber, error) {
+			return redisstream.NewSubscriber(redisstream.SubscriberConfig{
+				Client:        redisClient,
+				ConsumerGroup: params.HandlerName,
+			}, logger)
+		},
+		Marshaler: marshaler,
+		Logger:    logger,
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	err = eventProcessor.AddHandlers(
+		cqrs.NewEventHandler(
+			"OnOrderPlacedHandler",
+			func(ctx context.Context, event *OrderPlaced) error {
+				if event.OrderID == "" {
+					fmt.Println("ERROR: Received order placed without order_id")
+					return fmt.Errorf("empty order_id")
+				}
+
+				fmt.Println("Received order placed:", event.OrderID)
+
+				return nil
+			},
+		),
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	go func() {
+		err = delayedRequeuer.Run(context.Background())
+		if err != nil {
+			panic(err)
+		}
+	}()
+
+	go func() {
+		err = router.Run(context.Background())
+		if err != nil {
+			panic(err)
+		}
+	}()
+
+	<-router.Running()
+
+	i := 0
+
+	for {
+		e := newFakeOrderPlaced()
+
+		i++
+
+		if i == 10 {
+			e.OrderID = ""
+			i = 0
+		}
+
+		err = eventBus.Publish(context.Background(), e)
+		if err != nil {
+			panic(err)
+		}
+
+		time.Sleep(1 * time.Second)
+	}
+}
+
+func newFakeOrderPlaced() OrderPlaced {
+	var products []Product
+
+	for i := 0; i < rand.Intn(5)+1; i++ {
+		products = append(products, Product{
+			ID:   watermill.NewShortUUID(),
+			Name: gofakeit.ProductName(),
+		})
+	}
+
+	return OrderPlaced{
+		OrderID: watermill.NewUUID(),
+		Customer: Customer{
+			ID:    watermill.NewULID(),
+			Name:  gofakeit.Name(),
+			Email: gofakeit.Email(),
+			Phone: gofakeit.Phone(),
+		},
+		Address: Address{
+			Street:  gofakeit.Street(),
+			City:    gofakeit.City(),
+			Zip:     gofakeit.Zip(),
+			Country: gofakeit.Country(),
+		},
+		Products: products,
+	}
+}
+
+type OrderPlaced struct {
+	OrderID  string    `json:"order_id"`
+	Customer Customer  `json:"customer"`
+	Address  Address   `json:"address"`
+	Products []Product `json:"products"`
+}
+
+type Customer struct {
+	ID    string `json:"id"`
+	Name  string `json:"name"`
+	Email string `json:"email"`
+	Phone string `json:"phone"`
+}
+
+type Address struct {
+	Street  string `json:"street"`
+	City    string `json:"city"`
+	Zip     string `json:"zip"`
+	Country string `json:"country"`
+}
+
+type Product struct {
+	ID   string `json:"id"`
+	Name string `json:"name"`
+}