Add example producer using DeferredConfirm

Signed-off-by: Aitor Pérez Cedres <acedres@vmware.com>

_examples/sequential-producer/producer.go

@@ -0,0 +1,128 @@
+// This example declares a durable exchange, and publishes one messages to that
+// exchange. This example waits for a publish-confirmation before sending another
+// message.
+//
+package main
+
+import (
+	"context"
+	"flag"
+	amqp "github.com/rabbitmq/amqp091-go"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+)
+
+var (
+	uri          = flag.String("uri", "amqp://guest:guest@localhost:5672/", "AMQP URI")
+	exchange     = flag.String("exchange", "test-exchange", "Durable AMQP exchange name")
+	exchangeType = flag.String("exchange-type", "direct", "Exchange type - direct|fanout|topic|x-custom")
+	routingKey   = flag.String("key", "test-key", "AMQP routing key")
+	body         = flag.String("body", "foobar", "Body of message")
+	continuous   = flag.Bool("continuous", false, "Keep publishing messages at a 1msg/sec rate")
+	ErrLog       = log.New(os.Stderr, "[ERROR] ", log.LstdFlags|log.Lmsgprefix)
+	Log          = log.New(os.Stdout, "[INFO] ", log.LstdFlags|log.Lmsgprefix)
+)
+
+func init() {
+	flag.Parse()
+}
+
+func main() {
+	done := make(chan struct{})
+
+	SetupCloseHandler(done)
+
+	publish(context.Background(), done)
+}
+
+func publish(ctx context.Context, done chan struct{}) {
+	config := amqp.Config{
+		Vhost:      "/",
+		Properties: amqp.NewConnectionProperties(),
+	}
+	config.Properties.SetClientConnectionName("sequential-producer")
+
+	Log.Printf("dialing %s", uri)
+	conn, err := amqp.Dial(*uri)
+	if err != nil {
+		ErrLog.Fatalf("error in dial: %s", err)
+	}
+	defer conn.Close()
+
+	Log.Println("got Connection, getting Channel")
+	channel, err := conn.Channel()
+	if err != nil {
+		ErrLog.Fatalf("error getting a channel: %s", err)
+	}
+
+	Log.Printf("declaring exchange")
+	if err := channel.ExchangeDeclare(
+		*exchange,     // name
+		*exchangeType, // type
+		true,          // durable
+		false,         // auto-deleted
+		false,         // internal
+		false,         // noWait
+		nil,           // arguments
+	); err != nil {
+		ErrLog.Fatalf("Exchange Declare: %s", err)
+	}
+
+	// Reliable publisher confirms require confirm.select support from the
+	// connection.
+	Log.Printf("enabling publisher confirms.")
+	if err := channel.Confirm(false); err != nil {
+		ErrLog.Fatalf("Channel could not be put into confirm mode: %s", err)
+	}
+
+	for {
+		Log.Printf("publishing %dB body (%q)", len(*body), *body)
+		dConfirmation, err := channel.PublishWithDeferredConfirmWithContext(
+			ctx,
+			*exchange,
+			*routingKey,
+			false,
+			false,
+			amqp.Publishing{
+				Headers:         amqp.Table{},
+				ContentType:     "text/plain",
+				ContentEncoding: "",
+				DeliveryMode:    amqp.Persistent,
+				Priority:        0,
+				AppId:           "sequential-producer",
+				Body:            []byte(*body),
+			},
+		)
+		if err != nil {
+			ErrLog.Fatalf("error in publish: %s", err)
+		}
+
+		dConfirmation.Wait()
+		Log.Printf("confirmed delivery with tag: %d", dConfirmation.DeliveryTag)
+
+		if *continuous {
+			select {
+			case <-done:
+				Log.Println("producer is stopping")
+				return
+			case <-time.After(time.Second):
+				continue
+			}
+		} else {
+			break
+		}
+	}
+}
+
+func SetupCloseHandler(done chan struct{}) {
+	c := make(chan os.Signal, 2)
+	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
+	go func() {
+		<-c
+		close(done)
+		Log.Printf("Ctrl+C pressed in Terminal")
+	}()
+}