Piwik\Plugins\Installation\Controller::checkPiwikIsNotInstalled PHP Method

    private function checkPiwikIsNotInstalled()
    {
        if (!SettingsPiwik::isPiwikInstalled()) {
            return;
        }
        \Piwik\Plugins\Login\Controller::clearSession();
        $message = Piwik::translate('Installation_InvalidStateError', array('<br /><strong>', '</strong><a id="piwik-is-already-installed" href=\'' . Common::sanitizeInputValue(Url::getCurrentUrlWithoutFileName()) . '\'>', '</a>'));
        Piwik::exitWithErrorMessage($message);
    }