platform

rabbit/topic.go

@@ -0,0 +1,64 @@
+package rabbit
+
+import (
+	"encoding/json"
+	"log"
+	"time"
+
+	"git.k6n.net/mats/platform/event"
+	amqp "github.com/rabbitmq/amqp091-go"
+)
+
+// PublishEvent marshals an event.Event and publishes it to exchange with
+// routingKey = string(ev.Type). Opens and closes a channel per call. The
+// exchange must already exist (declare it with ListenToPattern or call
+// ExchangeDeclare explicitly before the first publish).
+func PublishEvent(c *amqp.Connection, exchange string, ev event.Event) error {
+	body, err := json.Marshal(ev)
+	if err != nil {
+		return err
+	}
+	ch, err := c.Channel()
+	if err != nil {
+		return err
+	}
+	defer ch.Close()
+	return ch.Publish(exchange, string(ev.Type), true, false, amqp.Publishing{
+		ContentType:  "application/json",
+		Body:         body,
+		DeliveryMode: amqp.Persistent,
+		Timestamp:    time.Now(),
+	})
+}
+
+// ListenToPattern binds an exclusive queue with a routing-key pattern (wildcard)
+// on a durable topic exchange, so one subscription receives every message
+// matching the pattern. A handler error nacks (drops) that single message and
+// keeps consuming.
+func ListenToPattern(ch *amqp.Channel, exchange, pattern string, handler func(amqp.Delivery) error) error {
+	if err := ch.ExchangeDeclare(exchange, "topic", true, false, false, false, nil); err != nil {
+		return err
+	}
+	q, err := ch.QueueDeclare("", false, false, true, false, nil)
+	if err != nil {
+		return err
+	}
+	if err := ch.QueueBind(q.Name, pattern, exchange, false, nil); err != nil {
+		return err
+	}
+	msgs, err := ch.Consume(q.Name, "", false, false, false, false, nil)
+	if err != nil {
+		return err
+	}
+	go func() {
+		for d := range msgs {
+			if err := handler(d); err != nil {
+				log.Printf("Error processing pattern message: %v", err)
+				d.Nack(false, false)
+			} else {
+				d.Ack(false)
+			}
+		}
+	}()
+	return nil
+}