高并发下论坛间歇性出现(Discuz! Database Error)Bug修复

discus999

Bug：高并发下，pre_common_session会员认证表的delete操作表锁冲突导致数据库连接数耗尽，适用X3.2、X3.4


Fix：
public function delete_by_session($session, $onlinehold, $guestspan) {
        if(!empty($session) && is_array($session)) {
                $onlinehold = time() - $onlinehold;
                $guestspan = time() - $guestspan;
                $session = daddslashes($session);


                $condition = " sid='{$session[sid]}' ";
                $condition .= " OR lastactivity<$onlinehold ";
                $condition .= " OR (uid='0' AND ip1='{$session['ip1']}' AND ip2='{$session['ip2']}' AND ip3='{$session['ip3']}' AND ip4='{$session['ip4']}' AND lastactivity>$guestspan) ";
                $condition .= $session['uid'] ? " OR (uid='{$session['uid']}') " : '';
                //DB::delete('common_session', $condition);
               //fix by wangxj
                $query = DB::query("SELECT sid FROM ".DB::table('common_session')." WHERE $condition");
                $sids = array();
                while ($row = DB::fetch($query)) {
                        $sids[] = $row['sid'];
                }
                // 按主键sid删除
                if (!empty($sids)) {
                        DB::delete('common_session', DB::field('sid', $sids));
                }
        }
}