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

_examples/basic/2-realtime-feed/producer/main.go

@@ -0,0 +1,110 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"math/rand"
+	"os"
+	"os/signal"
+	"sync"
+	"time"
+
+	"github.com/brianvoe/gofakeit/v6"
+
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill-kafka/v3/pkg/kafka"
+	"github.com/ThreeDotsLabs/watermill/message"
+	"github.com/ThreeDotsLabs/watermill/message/router/middleware"
+)
+
+var (
+	brokers = []string{"kafka:9092"}
+
+	messagesPerSecond = 100
+	numWorkers        = 20
+)
+
+func main() {
+	logger := watermill.NewStdLogger(false, false)
+	logger.Info("Starting the producer", watermill.LogFields{})
+
+	publisher, err := kafka.NewPublisher(
+		kafka.PublisherConfig{
+			Brokers:   brokers,
+			Marshaler: kafka.DefaultMarshaler{},
+		},
+		logger,
+	)
+	if err != nil {
+		panic(err)
+	}
+	defer publisher.Close()
+
+	closeCh := make(chan struct{})
+	workersGroup := &sync.WaitGroup{}
+	workersGroup.Add(numWorkers)
+
+	for i := 0; i < numWorkers; i++ {
+		go worker(publisher, workersGroup, closeCh)
+	}
+
+	// wait for SIGINT
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
+	<-c
+
+	// signal for the workers to stop publishing
+	close(closeCh)
+
+	// Waiting for all messages to be published
+	workersGroup.Wait()
+
+	logger.Info("All messages published", nil)
+}
+
+// worker publishes messages until closeCh is closed.
+func worker(publisher message.Publisher, wg *sync.WaitGroup, closeCh chan struct{}) {
+	ticker := time.NewTicker(time.Duration(int(time.Second) / messagesPerSecond))
+
+	for {
+		select {
+		case <-closeCh:
+			ticker.Stop()
+			wg.Done()
+			return
+
+		case <-ticker.C:
+		}
+
+		msgPayload := postAdded{
+			OccurredOn: time.Now(),
+			Author:     gofakeit.Username(),
+			Title:      gofakeit.Sentence(rand.Intn(5) + 1),
+			Content:    gofakeit.Sentence(rand.Intn(10) + 5),
+		}
+
+		payload, err := json.Marshal(msgPayload)
+		if err != nil {
+			panic(err)
+		}
+
+		msg := message.NewMessage(watermill.NewUUID(), payload)
+
+		// Use a middleware to set the correlation ID, it's useful for debugging
+		middleware.SetCorrelationID(watermill.NewShortUUID(), msg)
+		err = publisher.Publish("posts_published", msg)
+		if err != nil {
+			fmt.Println("cannot publish message:", err)
+			continue
+		}
+	}
+}
+
+type postAdded struct {
+	OccurredOn time.Time `json:"occurred_on"`
+
+	Author string `json:"author"`
+	Title  string `json:"title"`
+
+	Content string `json:"content"`
+}