diff --git a/transport/ray/direct.go b/transport/ray/direct.go
index f9406f8e3..e26348c24 100644
--- a/transport/ray/direct.go
+++ b/transport/ray/direct.go
@@ -143,15 +143,20 @@ func (s *Stream) ReadTimeout(timeout time.Duration) (buf.MultiBuffer, error) {
 	}
 }
 
+// Size returns the number of bytes hold in the Stream.
+func (s *Stream) Size() uint64 {
+	s.access.RLock()
+	defer s.access.RUnlock()
+
+	return s.size
+}
+
 func (s *Stream) waitForStreamSize() error {
 	if streamSizeLimit == 0 {
 		return nil
 	}
 
-	s.access.RLock()
-	defer s.access.RUnlock()
-
-	for streamSizeLimit > 0 && s.size >= streamSizeLimit {
+	for s.Size() >= streamSizeLimit {
 		select {
 		case <-s.ctx.Done():
 			return io.ErrClosedPipe