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)
+}

backend/internal/middleware/rabbitmq/rabbitMQ.go

@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"errors"
 	"feedsystem_video_go/internal/config"
+	"log"
 	"strconv"
 	"time"
 
@@ -73,19 +74,25 @@ func (r *RabbitMQ) DeclareTopic(exchange string, queue string, bindingKey string
 		false,
 		false,
 		false,
-		nil,
+		amqp.Table{"x-dead-letter-exchange": DLXExchange},
 	)
 	if err != nil {
 		return err
 	}
 
-	return r.Ch.QueueBind(
+	if err := r.Ch.QueueBind(
 		q.Name,
 		bindingKey,
 		exchange,
 		false,
 		nil,
-	)
+	); err != nil {
+		return err
+	}
+	if err := DeclareDLX(r.Ch, queue); err != nil {
+		log.Printf("DLX declare failed for %s: %v", queue, err)
+	}
+	return nil
 }
 
 func (r *RabbitMQ) PublishJSON(ctx context.Context, exchange string, routingKey string, payload any) error {

backend/internal/worker/commentworker.go

@@ -59,7 +59,13 @@ func (w *CommentWorker) Run(ctx context.Context) error {
 
 func (w *CommentWorker) handleDelivery(ctx context.Context, d amqp.Delivery) {
 	if err := w.process(ctx, d.Body); err != nil {
-		log.Printf("comment worker: failed to process message: %v", err)
+		retryCount := rabbitmq.GetRetryCount(d)
+		if retryCount >= rabbitmq.MaxRetryCount {
+			log.Printf("comment worker: max retries exceeded (%d), moving to DLX: %v", retryCount, err)
+			_ = d.Ack(false)
+			return
+		}
+		log.Printf("comment worker: failed (retry %d/%d): %v", retryCount+1, rabbitmq.MaxRetryCount, err)
 		_ = d.Nack(false, true)
 		return
 	}

backend/internal/worker/likeworker.go

@@ -58,7 +58,13 @@ func (w *LikeWorker) Run(ctx context.Context) error {
 
 func (w *LikeWorker) handleDelivery(ctx context.Context, d amqp.Delivery) {
 	if err := w.process(ctx, d.Body); err != nil {
-		log.Printf("like worker: failed to process message: %v", err)
+		retryCount := rabbitmq.GetRetryCount(d)
+		if retryCount >= rabbitmq.MaxRetryCount {
+			log.Printf("like worker: max retries exceeded (%d), moving to DLX: %v", retryCount, err)
+			_ = d.Ack(false)
+			return
+		}
+		log.Printf("like worker: failed (retry %d/%d): %v", retryCount+1, rabbitmq.MaxRetryCount, err)
 		_ = d.Nack(false, true)
 		return
 	}

backend/internal/worker/popularityworker.go

@@ -58,7 +58,13 @@ func (w *PopularityWorker) Run(ctx context.Context) error {
 
 func (w *PopularityWorker) handleDelivery(ctx context.Context, d amqp.Delivery) {
 	if err := w.process(ctx, d.Body); err != nil {
-		log.Printf("popularity worker: failed to process message: %v", err)
+		retryCount := rabbitmq.GetRetryCount(d)
+		if retryCount >= rabbitmq.MaxRetryCount {
+			log.Printf("popularity worker: max retries exceeded (%d), moving to DLX: %v", retryCount, err)
+			_ = d.Ack(false)
+			return
+		}
+		log.Printf("popularity worker: failed (retry %d/%d): %v", retryCount+1, rabbitmq.MaxRetryCount, err)
 		_ = d.Nack(false, true)
 		return
 	}

backend/internal/worker/socialworker.go

@@ -58,8 +58,13 @@ func (w *SocialWorker) Run(ctx context.Context) error {
 
 func (w *SocialWorker) handleDelivery(ctx context.Context, d amqp.Delivery) {
 	if err := w.process(ctx, d.Body); err != nil {
-		log.Printf("social worker: failed to process message: %v", err)
+		retryCount := rabbitmq.GetRetryCount(d)
-		// 重新入队，稍后重试
+		if retryCount >= rabbitmq.MaxRetryCount {
+			log.Printf("social worker: max retries exceeded (%d), moving to DLX: %v", retryCount, err)
+			_ = d.Ack(false)
+			return
+		}
+		log.Printf("social worker: failed (retry %d/%d): %v", retryCount+1, rabbitmq.MaxRetryCount, err)
 		_ = d.Nack(false, true)
 		return
 	}