// WriteTo writes the length and contents of the engine to w.
func (s *Store) WriteTo(w io.Writer) (n int64, err error) {
tx, err := s.db.Begin(false)
if err != nil {
return 0, err
}
defer tx.Rollback()
// Set content length header, if an HTTP response writer.
if w, ok := w.(http.ResponseWriter); ok {
w.Header().Set("Content-Length", strconv.FormatInt(tx.Size(), 10))
}
// Write data.
return tx.WriteTo(w)
}