code: public function setSavePath($value)
      {
          $path = Yii::getAlias($value);
          if (is_dir($path)) {
              session_save_path($path);
          } else {
              throw new InvalidArgumentException("Session save path is not a valid directory: $value");
          }
      }
docs: Sets the current session save path.
  This is a wrapper for [PHP session_save_path()](https://secure.php.net/manual/en/function.session-save-path.php).
  @param string $value the current session save path. This can be either a directory name or a [path alias](guide:concept-aliases).
  @throws InvalidArgumentException if the path is not a valid directory