PHP에서 한 명의 사용자만 로그인하는 방법

//初始化
socket.on('init', () => { //连接初始化
socket.send({
type: 'login',
token: uni.getStorageSync('access_token'),
device_no: plus.device.uuid,//手机设备唯一编号
});
}).on('quit_push',(res)=> {
if(res) {
uni.showModal({
title: '退出通知',
content: '你的账号在其他设备上登录！',
showCancel: true,
cancelText: '取消',
confirmText: '确定',
success: res => {
if(res.confirm) {
uni.clearStorageSync()
store.commit('chat/clear')
uni.reLaunch({
url:"../../pages/login/index"
})
}else if(res.cancel) {
uni.clearStorageSync()
store.commit('chat/clear')
uni.reLaunch({
url:"../../pages/login/index"
})
}
}
});
}
});

$is_online = Db::name('UserLoginClient')->where('user_id',$user['id'])->order('id desc')->find();
if(isset($device_no) && $device_no && $is_online['device_no'] != $device_no && !empty($is_online['device_no'])) { 
Tools::sendToClient($is_online['client_id'],json_encode([
'type' => 'quit_push',
'data' => 'ip',
'message' => '强制下线'
]));
}

public static function sendToClient($client_id, $message)
    {
        Gateway::sendToClient($client_id, $message);
    }

if (self::$headToken && Cache::has(self::$prefix . self::$userId)) {
            if (self::$headToken == Cache::get(self::$prefix . self::$userId)) {
                Cache::set(self::$prefix . self::$userId, self::$headToken, self::$timeOut);
            } else {        // 换了手机,客户端重新发送pushtoken到服务端，服务端与缓存中的pushtoken比较，不同则给原来pushtoken手机推送一条并重新缓存新的token
                // modify by wensen on 20180816
                // $addr = getCity();
                $addr = getMobCity();
                $ip = request()->ip();
                
                if ($addr) {
                    $addr['province'] = empty($addr['province']) ? '' : $addr['province'];
                    $addr['city'] = empty($addr['city']) ? '' : $addr['city'];
                    // $address = "\t" . $addr['country'] . "-" . $addr['region'] . "-" . $addr['city'] . " (IP:" . $ip . ")\t";
                    $address = "\t" . $addr['country'] . "-" . $addr['province'] . "-" . $addr['city'] . " (IP:" . $ip . ")\t";
                } else {
                    $address = "IP:" . $ip . "";
                }
                $OldToken = Cache::get(self::$prefix . self::$userId);
                if (strlen($OldToken) == 64) {
                    $content = array(
                        'title' => 'APP紧急通知',
                        'body' => '您的账号于:' . date('Y-m-d H:i:s') . '在' . $address . '处登录,若不为您本人登录,请您立即修改密码!',
                        'pull_service' => 'login'
                    );
                    \umeng\Push::send($OldToken, 'unicast', $content, 'message', true);
                } elseif (strlen($OldToken) == 44) {
                    $content = array(
                        'pull_service' => 'login',
                        'msg' => '您的账号于:' . date('Y-m-d H:i:s') . '在' . $address . '处登录,若不为您本人登录,请您立即修改密码!'
                    );
                    \umeng\Push::send($OldToken, 'unicast', $content, 'message', true);
                }
                Cache::set(self::$prefix . self::$userId, self::$headToken, self::$timeOut);
            }
        } else {
            Cache::set(self::$prefix . self::$userId, self::$headToken, self::$timeOut);
        }