protected function init()
 {
     parent::init();
     if (!extension_loaded('XCache')) {
         throw new waException("XCache module not loaded");
     }
     if (version_compare(phpversion("XCache"), "3.1.0", "<")) {
         throw new waException("XCache version 3.1.0 or newer required");
     }
     if (!isset($this->options["prefix"])) {
         throw new waException("Prefix for XCache is not set");
     }
 }