feat!: update SQS receiveMessage to return no messages error when no …

…messages received from the queue

aws/sqs/sqs.go

@@ -27,6 +27,9 @@ type SQS struct {
 	client *sqs.Client
 }
 
+// specific error to return when no messages are received from the queue
+var ErrNoMessages = errors.New("no messages received from queue")
+
 // New returns an SQS struct which wraps an SQS client using the default AWS credentials chain.
 // This consults (in order) environment vars, config files, EC2 and ECS roles.
 // It is an error if the AWS_REGION environment variable is not set.
@@ -125,29 +128,28 @@ func (s *SQS) ReceiveWithContextAttributes(ctx context.Context, queueURL string,
 // receiveMessage is the common code used internally to receive an SQS message based
 // on the provided input.
 func (s *SQS) receiveMessage(ctx context.Context, input *sqs.ReceiveMessageInput) (Raw, error) {
+	r, err := s.client.ReceiveMessage(ctx, input)
+	if err != nil {
+		return Raw{}, err
+	}
 
-	for {
-		r, err := s.client.ReceiveMessage(ctx, input)
-		if err != nil {
-			return Raw{}, err
-		}
+	switch {
+	case r == nil || len(r.Messages) == 0:
+		// no message received
+		return Raw{}, ErrNoMessages
 
-		switch {
-		case r == nil || len(r.Messages) == 0:
-			// no message received
-			continue
-		case len(r.Messages) == 1:
-			raw := r.Messages[0]
-
-			m := Raw{
-				Body:          aws.ToString(raw.Body),
-				ReceiptHandle: aws.ToString(raw.ReceiptHandle),
-				Attributes:    raw.Attributes,
-			}
-			return m, nil
-		case len(r.Messages) > 1:
-			return Raw{}, fmt.Errorf("received more than 1 message: %d", len(r.Messages))
+	case len(r.Messages) == 1:
+		raw := r.Messages[0]
+
+		m := Raw{
+			Body:          aws.ToString(raw.Body),
+			ReceiptHandle: aws.ToString(raw.ReceiptHandle),
+			Attributes:    raw.Attributes,
 		}
+		return m, nil
+
+	default:
+		return Raw{}, fmt.Errorf("received unexpected messages: %d", len(r.Messages))
 	}
 }
 
@@ -333,3 +335,7 @@ func Cancelled(err error) bool {
 	}
 	return false
 }
+
+func IsNoMessagesError(err error) bool {
+	return errors.Is(err, ErrNoMessages)
+}