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

_examples/pubsubs/sqlite/main.go

@@ -0,0 +1,90 @@
+// Sources for https://watermill.io/docs/getting-started/
+package main
+
+import (
+	"context"
+	"database/sql"
+	"log"
+	"time"
+
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill-sqlite/wmsqlitemodernc"
+	"github.com/ThreeDotsLabs/watermill/message"
+	_ "modernc.org/sqlite"
+)
+
+func main() {
+	db := createDB()
+	defer db.Close()
+	logger := watermill.NewStdLogger(false, false)
+
+	subscriber, err := wmsqlitemodernc.NewSubscriber(
+		db,
+		wmsqlitemodernc.SubscriberOptions{
+			InitializeSchema: true,
+			Logger:           logger,
+		},
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	messages, err := subscriber.Subscribe(context.Background(), "example_topic")
+	if err != nil {
+		panic(err)
+	}
+
+	go process(messages)
+
+	publisher, err := wmsqlitemodernc.NewPublisher(
+		db,
+		wmsqlitemodernc.PublisherOptions{
+			InitializeSchema: true,
+			Logger:           logger,
+		},
+	)
+	if err != nil {
+		panic(err)
+	}
+	publishMessages(publisher)
+}
+
+func createDB() *sql.DB {
+	connectionDSN := ":memory:" // or "db.sqlite3?journal_mode=WAL&busy_timeout=1000&cache=shared"
+	db, err := sql.Open("sqlite", connectionDSN)
+	if err != nil {
+		panic(err)
+	}
+	// limit the number of concurrent connections to one
+	// this is a limitation of `modernc.org/sqlite` driver
+	db.SetMaxOpenConns(1)
+
+	err = db.Ping()
+	if err != nil {
+		panic(err)
+	}
+
+	return db
+}
+
+func publishMessages(publisher message.Publisher) {
+	for {
+		msg := message.NewMessage(watermill.NewUUID(), []byte(`{"message": "Hello, world!"}`))
+
+		if err := publisher.Publish("example_topic", msg); err != nil {
+			panic(err)
+		}
+
+		time.Sleep(time.Second)
+	}
+}
+
+func process(messages <-chan *message.Message) {
+	for msg := range messages {
+		log.Printf("received message: %s, payload: %s", msg.UUID, string(msg.Payload))
+
+		// we need to Acknowledge that we received and processed the message,
+		// otherwise, it will be resent over and over again.
+		msg.Ack()
+	}
+}