public static function getFastest($appkey, $hosts)
 {
     if ($hosts == null || count($hosts) == 0) {
         throw new Exception("Hosts cann't be null or size must greater than 0");
     }
     if (isset(ApiUrlRespectUtils::$appkeyAndFasterHost[$appkey]) && count(array_diff($hosts, isset(ApiUrlRespectUtils::$appKeyAndHost[$appkey]) ? ApiUrlRespectUtils::$appKeyAndHost[$appkey] : null)) == 0) {
         return ApiUrlRespectUtils::$appkeyAndFasterHost[$appkey];
     } else {
         $fastest = ApiUrlRespectUtils::getFastestRealTime($hosts);
         ApiUrlRespectUtils::$appKeyAndHost[$appkey] = $hosts;
         ApiUrlRespectUtils::$appkeyAndFasterHost[$appkey] = $fastest;
         return $fastest;
     }
 }