isPurgeRequestAllowed example

    protected function invalidate(Request $request, $catch = false)
    {
        if ($request->getMethod() !== 'BAN' && $request->getMethod() !== 'PURGE') {
            return parent::invalidate($request, $catch);
        }

        // Reject all non-authorized clients         if (!$this->isPurgeRequestAllowed($request)) {
            return new Response('', 405);
        }

        $response = new Response();

        if ($request->getMethod() === 'BAN') {
            if ($request->headers->has('x-shopware-invalidates')) {
                $cacheId = $request->headers->get('x-shopware-invalidates');
                $result = $this->getStore()->purgeByHeader('x-shopware-cache-id', $cacheId);
            } else {
                $result = $this->getStore()->purgeAll();
            }