server: add txn check (#2920)
server: add txn check (#2920)


ueizhou/tidb,qhsong/tidb,kyle-wang/tidb,gaocegege/tidb,ming-relax/tidb,8cbx/tidb,wusphinx/tidb,pingcap/tidb,anywhy/tidb,yuanwhy/tidb,ngaut/tidb,simon-xia/tidb,kyle-wang/tidb,JinheLin/tidb,ngaut/tidb,silentred/tidb,c4pt0r/tidb,silentred/tidb,simon-xia/tidb,astaxie/tidb,yangwenmai/tidb,mccxj/tidb,XuHuaiyu/tidb,c4pt0r/tidb,Cofyc/tidb,myrice/tidb,ngaut/tidb,cosmtrek/tidb,kyle-wang/tidb,zimulala/tidb,Nify/tidb,qiuyesuifeng/tidb,ngaut/tidb,Cofyc/tidb,CodeRushing/tidb,EvilMcJerkface/tidb,JinheLin/tidb,spongedu/tidb,spongedu/tidb,8cbx/tidb,c4pt0r/tidb,zimulala/tidb,louishust/tidb,c4pt0r/tidb,wusphinx/tidb,ueizhou/tidb,astaxie/tidb,pingcap/tidb,gaocegege/tidb,CodeRushing/tidb,c4pt0r/tidb,yuanwhy/tidb,mccxj/tidb,qhsong/tidb,EvilMcJerkface/tidb,zs634134578/tidb,ngaut/tidb,pingcap/tidb,pingcap/tidb,cosmtrek/tidb,XuHuaiyu/tidb,pingcap/tidb,c4pt0r/tidb,tiancaiamao/tidb,pingcap/tidb,kyle-wang/tidb,liyu4/tidb,qiuyesuifeng/tidb,kyle-wang/tidb,anywhy/tidb,yangwenmai/tidb,myrice/tidb,coocood/tidb,liyu4/tidb,ming-relax/tidb,coocood/tidb,louishust/tidb,zs634134578/tidb,kyle-wang/tidb,tiancaiamao/tidb,ngaut/tidb,Nify/tidb