Gdn_Session::getStashSession PHP Method

    private function getStashSession($sql, $valueToStash)
    {
        $cookieName = c('Garden.Cookie.Name', 'Vanilla');
        $name = $cookieName . '-sid';
        // Grab the entire session record.
        $sessionID = val($name, $_COOKIE, '');
        // If there is no session, and no value for saving, return.
        if ($sessionID == '' && $valueToStash == '') {
            return false;
        }
        $session = $sql->select()->from('Session')->where('SessionID', $sessionID)->get()->firstRow();
        if (!$session) {
            $sessionID = betterRandomString(32);
            $transientKey = substr(md5(mt_rand()), 0, 11) . '!';
            // Save the session information to the database.
            $sql->insert('Session', ['SessionID' => $sessionID, 'UserID' => Gdn::session()->UserID, 'TransientKey' => $transientKey, 'DateInserted' => Gdn_Format::toDateTime(), 'DateUpdated' => Gdn_Format::toDateTime()]);
            trace("Inserting session stash {$sessionID}");
            $session = $sql->select()->from('Session')->where('SessionID', $sessionID)->get()->firstRow();
            // Save a session cookie.
            $path = c('Garden.Cookie.Path', '/');
            $domain = c('Garden.Cookie.Domain', '');
            $expire = 0;
            // If the domain being set is completely incompatible with the
            // current domain then make the domain work.
            $currentHost = Gdn::request()->host();
            if (!stringEndsWith($currentHost, trim($domain, '.'))) {
                $domain = '';
            }
            safeCookie($name, $sessionID, $expire, $path, $domain);
            $_COOKIE[$name] = $sessionID;
        }
        $session->Attributes = dbdecode($session->Attributes);
        if (!$session->Attributes) {
            $session->Attributes = [];
        }
        return $session;
    }