protected static function ensure_ready_for_stats($store, $definition, $mode = cache_store::MODE_APPLICATION) {
        // This function is performance-sensitive, so exit as quickly as possible
        // if we do not need to do anything.
        if (isset(self::$stats[$definition]['stores'][$store])) {
            return;
        }
        if (!array_key_exists($definition, self::$stats)) {
            self::$stats[$definition] = array(
                'mode' => $mode,
                'stores' => array(
                    $store => array(
                        'hits' => 0,
                        'misses' => 0,
                        'sets' => 0,
                    )
                )
            );
        } else if (!array_key_exists($store, self::$stats[$definition]['stores'])) {
            self::$stats[$definition]['stores'][$store] = array(
                'hits' => 0,
                'misses' => 0,
                'sets' => 0,
            );
        }
    }