packet with ack id 1emitting packet with ack id 2？？？下线了如何减去相对应的？

// 当有客户端连接时
         $io->on('connection', function($socket) {
            // 定义chat message事件回调函数
            $socket->on('init', function ($data) use($socket) {
                $data = json_decode($data, true);
                $socket->uid = $data['uid'];
                static::$online[$data['uid']] =$socket;
                $socket->emit('init', 'login listen success', function ($res){});
            });
});