PHP 统计目录下文件数和文件大小

/**
 * 统计文件数和文件大小
 */
private function getFileCacheCount($pathName)
{
    $data = [
        'num' => 0,
        'size' => 0
    ];
    if (file_exists($pathName)) {
        $dir = opendir($pathName);
        while(false !== ($file_name = readdir($dir))){
            if(!($file_name == "." || $file_name == "..")){
                $fileName = $pathName . "/" . $file_name;
                if(is_dir($fileName)){
                    $subData = $this->getFileCacheCount($fileName);
                    $data['size'] += $subData['size'];
                    $data['num'] += $subData['num'];
                }else{
                    $data['size'] += filesize($fileName);
                    $data['num']++;
                }
            }
        }
        closedir($dir);
    }
    return $data;
}