public static function deleteAllCached()
 {
     foreach (self::$_cached as $url => $tempFile) {
         if (XenForo_Application::debugMode()) {
             $fileSize = @filesize($tempFile);
         }
         $deleted = @unlink($tempFile);
         if (XenForo_Application::debugMode()) {
             XenForo_Helper_File::log(__CLASS__, call_user_func_array('sprintf', array('delete %s -> %s, %s, %d bytes', $url, $tempFile, $deleted ? 'succeeded' : 'failed', !empty($fileSize) ? $fileSize : 0)));
         }
     }
     self::$_cached = array();
 }