src/web/Session.php
public function setSavePath($value)
    {
        $path = Yii::getAlias($value);
        if (is_dir($path)) {
            session_save_path($path);
        } else {
            throw new InvalidParamException("Session save path is not a valid directory: $value");
        }
    }
public function setSavePath($value)
    {
        $path = Yii::getAlias($value);
        if (is_dir($path)) {
            session_save_path($path);
        } else {
            throw new InvalidParamException("Session save path is not a valid directory: $value");
        }
    }
Sets the current session save path.
This is a wrapper for [PHP session_save_path()](http://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.
@throws InvalidParamException if the path is not a valid directory