class AbstractSessionHandler

abstract class AbstractSessionHandler implements \SessionHandlerInterface, \SessionUpdateTimestampHandlerInterface {
    private string $sessionName;
    private string $prefetchId;
    private string $prefetchData;
    private ?string $newSessionId = null;
    private string $igbinaryEmptyData;
    public function open(string $savePath, string $sessionName) : bool {
        $this->sessionName = $sessionName;
        if (!headers_sent() && !\ini_get('session.cache_limiter') && '0' !== \ini_get('session.cache_limiter')) {
            header(\sprintf('Cache-Control: max-age=%d, private, must-revalidate', 60 * (int) \ini_get('session.cache_expire')));
        }
        return true;
    }
    protected abstract function doRead(string $sessionId) : string;
    protected abstract function doWrite(string $sessionId, string $data) : bool;
    protected abstract function doDestroy(string $sessionId) : bool;
    public function validateId(string $sessionId) : bool {
        $this->prefetchData = $this->read($sessionId);
        $this->prefetchId = $sessionId;
        return '' !== $this->prefetchData;
    }
    public function read(string $sessionId) : string {
        if (isset($this->prefetchId)) {
            $prefetchId = $this->prefetchId;
            $prefetchData = $this->prefetchData;
            unset($this->prefetchId, $this->prefetchData);
            if ($prefetchId === $sessionId || '' === $prefetchData) {
                $this->newSessionId = '' === $prefetchData ? $sessionId : null;
                return $prefetchData;
            }
        }
        $data = $this->doRead($sessionId);
        $this->newSessionId = '' === $data ? $sessionId : null;
        return $data;
    }
    public function write(string $sessionId, string $data) : bool {
        // see https://github.com/igbinary/igbinary/issues/146
        $this->igbinaryEmptyData ??= \function_exists('igbinary_serialize') ? igbinary_serialize([]) : '';
        if ('' === $data || $this->igbinaryEmptyData === $data) {
            return $this->destroy($sessionId);
        }
        $this->newSessionId = null;
        return $this->doWrite($sessionId, $data);
    }
    public function destroy(string $sessionId) : bool {
        if (!headers_sent() && filter_var(\ini_get('session.use_cookies'), \FILTER_VALIDATE_BOOL)) {
            if (!isset($this->sessionName)) {
                throw new \LogicException(\sprintf('Session name cannot be empty, did you forget to call "parent::open()" in "%s"?.', static::class));
            }
            $cookie = SessionUtils::popSessionCookie($this->sessionName, $sessionId);
            
            /*
             * We send an invalidation Set-Cookie header (zero lifetime)
             * when either the session was started or a cookie with
             * the session name was sent by the client (in which case
             * we know it's invalid as a valid session cookie would've
             * started the session).
             */
            if (null === $cookie || isset($_COOKIE[$this->sessionName])) {
                $params = session_get_cookie_params();
                unset($params['lifetime']);
                setcookie($this->sessionName, '', $params);
            }
        }
        return $this->newSessionId === $sessionId || $this->doDestroy($sessionId);
    }

}