public function getCacheProvider($key = '', $options = array()) {
        $objCache = null;
        if (empty($key)) {
            $key = $this->getOption(xPDO::OPT_CACHE_KEY, $options, 'default');
        }
        $objCacheClass= 'xPDO\\Cache\\xPDOFileCache';
        if (!isset($this->caches[$key]) || !is_object($this->caches[$key])) {
            if ($cacheClass = $this->getOption($key . '_' . xPDO::OPT_CACHE_HANDLER, $options, $this->getOption(xPDO::OPT_CACHE_HANDLER, $options))) {
                $cacheClass = $this->xpdo->loadClass($cacheClass, XPDO_CORE_PATH, false, true);
                if ($cacheClass) {
                    $objCacheClass= $cacheClass;
                }
            }
            $options[xPDO::OPT_CACHE_KEY]= $key;
            $this->caches[$key] = new $objCacheClass($this->xpdo, $options);
            if (empty($this->caches[$key]) || !$this->caches[$key]->isInitialized()) {
                $this->caches[$key] = new xPDOFileCache($this->xpdo, $options);
            }
            $objCache = $this->caches[$key];
            $objCacheClass= get_class($objCache);
        } else {
            $objCache =& $this->caches[$key];
            $objCacheClass= get_class($objCache);
        }
        if ($this->xpdo->getDebug() === true) $this->xpdo->log(xPDO::LOG_LEVEL_DEBUG, "Returning {$objCacheClass}:{$key} cache provider from available providers: " . print_r(array_keys($this->caches), 1));
        return $objCache;
    }