public function getFolderSize($path = null)
{
$size = 0;
$root = !is_null($path) ? $path . '/' : '';
$object_list = $this->listFolder($root, null, true, false, true);
foreach ($object_list as $key => $val) {
$size += isset($val['subdirs']) ? $this->getFolderSize($root . '/' . $key) : $this->size($root, $key);
}
return $size;
}