public function getMeasurableSettingsStorage($idSite, $pluginName)
    {
        $id = 'measurableSettings' . (int) $idSite . '#' . $pluginName;

        if (empty($idSite)) {
            return $this->getNonPersistentStorage($id . '#nonpersistent');
        }

        if (!isset($this->cache[$id])) {
            $backend = new Backend\MeasurableSettingsTable($idSite, $pluginName);
            $this->cache[$id] = $this->makeStorage($backend);
        }

        return $this->cache[$id];
    }