public function del_by_tags($tags)
{
if (!is_array($tags)) {
$tags = array($tags);
}
$d = 0;
foreach ($tags as $tag) {
$keys = $this->redis->sMembers($this->tag_prefix . $tag);
if (!empty($keys)) {
$d += $this->del($keys);
}
$this->redis->Del($this->tag_prefix . $tag);
}
return $d;
}