Pimcore\Tool\Session::getReadOnly PHP Method

    public static function getReadOnly($namespace = "pimcore_admin")
    {
        $session = self::get($namespace, true);
        $session->lock();
        self::writeClose();
        return $session;
    }

 /**
  * @static
  * @throws Exception
  * @return User
  */
 public static function authenticateSession()
 {
     if (!isset($_COOKIE["pimcore_admin_sid"]) && !isset($_REQUEST["pimcore_admin_sid"])) {
         // if no session cookie / ID no authentication possible, we don't need to start a session
         return null;
     }
     $session = Session::getReadOnly();
     $user = $session->user;
     if ($user instanceof User) {
         // renew user
         $user = User::getById($user->getId());
         if (self::isValidUser($user)) {
             return $user;
         }
     }
     return null;
 }