(queueName string, handler MessageHandler)
| 51 | type MessageHandler func(context.Context, amqp.Delivery) error |
| 52 | |
| 53 | func (r *RabbitMQ) ConsumeMessages(queueName string, handler MessageHandler) error { |
| 54 | // Set prefetch count to 1 for fair dispatch |
| 55 | // This tells RabbitMQ not to give more than one message to a service at a time. |
| 56 | // The worker will only get the next message after it has acknowledged the previous one. |
| 57 | err := r.Channel.Qos( |
| 58 | 1, // prefetchCount: Limit to 1 unacknowledged message per consumer |
| 59 | 0, // prefetchSize: No specific limit on message size |
| 60 | false, // global: Apply prefetchCount to each consumer individually |
| 61 | ) |
| 62 | if err != nil { |
| 63 | return fmt.Errorf("failed to set QoS: %v", err) |
| 64 | } |
| 65 | |
| 66 | msgs, err := r.Channel.Consume( |
| 67 | queueName, // queue |
| 68 | "", // consumer |
| 69 | false, // auto-ack |
| 70 | false, // exclusive |
| 71 | false, // no-local |
| 72 | false, // no-wait |
| 73 | nil, // args |
| 74 | ) |
| 75 | if err != nil { |
| 76 | return err |
| 77 | } |
| 78 | |
| 79 | go func() { |
| 80 | for msg := range msgs { |
| 81 | if err := tracing.TracedConsumer(msg, func(ctx context.Context, d amqp.Delivery) error { |
| 82 | log.Printf("Received a message: %s", msg.Body) |
| 83 | |
| 84 | cfg := retry.DefaultConfig() |
| 85 | err := retry.WithBackoff(ctx, cfg, func() error { |
| 86 | return handler(ctx, d) |
| 87 | }) |
| 88 | if err != nil { |
| 89 | log.Printf("Message processing failed after %d retries for message ID: %s, err: %v", cfg.MaxRetries, d.MessageId, err) |
| 90 | |
| 91 | // Add failure context before sending to the DLQ |
| 92 | headers := amqp.Table{} |
| 93 | if d.Headers != nil { |
| 94 | headers = d.Headers |
| 95 | } |
| 96 | |
| 97 | headers["x-death-reason"] = err.Error() |
| 98 | headers["x-origin-exchange"] = d.Exchange |
| 99 | headers["x-original-routing-key"] = d.RoutingKey |
| 100 | headers["x-retry-count"] = cfg.MaxRetries |
| 101 | d.Headers = headers |
| 102 | |
| 103 | // Reject without requeue - message will go to the DLQ |
| 104 | _ = d.Reject(false) |
| 105 | return err |
| 106 | } |
| 107 | |
| 108 | // Only Ack if the handler succeeds |
| 109 | if ackErr := msg.Ack(false); ackErr != nil { |
| 110 | log.Printf("ERROR: Failed to Ack message: %v. Message body: %s", ackErr, msg.Body) |
no test coverage detected