function change_token($c, $dbo, $bottom = 10, $mail = true, $write = true)
{
    $sql = "select sina_token as st, unix_timestamp(token_update_at) as tua, token_expires_in as tei, user_id as uid from user_info_sina where sina_token IS NOT NULL limit 10";
    $sql_res = $dbo->getRs($sql);
    while (1) {
        foreach ($sql_res as $res) {
            $token = $res['st'];
            $uid = $res['uid'];
            $tua = $res['tua'];
            $tei = $res['tei'];
            $now = time();
            $left_time = $tua + $tei - $now;
            if ($left_time < 3600 && $left_time > 2650) {
                $msg = "user {$uid} 's token will expire in an hour.";
                $sub = "微动力提醒";
                if ($mail) {
                    mail_to_master($msg, $sub);
                } else {
                    $write_msg = "{$sub}: {$msg} \n";
                    write_line_with_time_and_newline($write_msg);
                }
            }
            //            var_dump($token);   // debug
            $c = new SaeTClientV2(WB_AKEY, WB_SKEY, $token);
            $api_left = api_left($c);
            //            var_dump($api_left);    // debug
            if ($api_left['user'] > $bottom) {
                $msg = 'token changed, user_id:' . "{$uid}\n";
                //                echo $msg;
                if ($write) {
                    write_line_with_time_and_newline($msg);
                }
                return $c;
            }
        }
        // 当前没有可用token了
        $msg = "no avilable token, exit.";
        //        echo $msg;
        write_line_with_time_and_newline($msg);
        exit;
    }
}
function change_token($c, $dbo)
{
    $sql = "select sina_token as st, user_id as uid from user where sina_token IS NOT NULL limit 10";
    $sql_res = $dbo->getRs($sql);
    while (1) {
        foreach ($sql_res as $res) {
            $token = $res['st'];
            //            var_dump($token);   // debug
            $c = new SaeTClientV2(WB_AKEY, WB_SKEY, $token);
            $api_left = api_left($c);
            //            var_dump($api_left);    // debug
            if ($api_left['user'] > 10) {
                $msg = 'token changed, user_id:' . "{$res['uid']}\n";
                //                echo $msg;
                write_log($msg);
                return $c;
            }
        }
        // 当前没有可用token了
        $msg = "no avilable token, exit.\n";
        //        echo $msg;
        write_line($msg);
        exit;
    }
}