feat(P1): MQ Worker 死信队列 — 重试上限3次后 Ack 移入 DLX

backend/internal/middleware/rabbitmq/dlx.go

@@ -0,0 +1,53 @@
+package rabbitmq
+
+import (
+	"log"
+
+	amqp "github.com/rabbitmq/amqp091-go"
+)
+
+const (
+	DLXExchange   = "dlx.events"
+	MaxRetryCount = 3
+)
+
+// DeclareDLX 声明死信交换机和对应的死信队列
+func DeclareDLX(ch *amqp.Channel, queueName string) error {
+	if ch == nil {
+		return nil
+	}
+	if err := ch.ExchangeDeclare(
+		DLXExchange, "topic", true, false, false, false, nil,
+	); err != nil {
+		return err
+	}
+	dlxQueue := queueName + ".dlx"
+	_, err := ch.QueueDeclare(
+		dlxQueue, true, false, false, false, nil,
+	)
+	if err != nil {
+		return err
+	}
+	if err := ch.QueueBind(dlxQueue, "#", DLXExchange, false, nil); err != nil {
+		return err
+	}
+	log.Printf("DLX ready: exchange=%s queue=%s", DLXExchange, dlxQueue)
+	return nil
+}
+
+// GetRetryCount 从 AMQP x-death header 中提取当前消息已被重试的次数
+func GetRetryCount(d amqp.Delivery) int {
+	deaths, ok := d.Headers["x-death"].([]interface{})
+	if !ok || len(deaths) == 0 {
+		return 0
+	}
+	death, ok := deaths[0].(amqp.Table)
+	if !ok {
+		return 0
+	}
+	count, ok := death["count"].(int64)
+	if !ok {
+		return 0
+	}
+	return int(count)
+}