When implicit XA transaction fail to commit and is automatically rollbacked, the real error should be returned to the user instead of OK packet.

[tankilo]

• dble version：
• preconditions ：
  no
• configs：

schema.xml

<table name="xa_test" dataNode="dn1,dn2" rule="sharding-by-mod2" primaryKey="ID"/>

rule.xml

<tableRule name="sharding-by-mod2">
        <rule>
            <columns>id</columns>
            <algorithm>hashmod2</algorithm>
        </rule>
    </tableRule>
    <function name="hashmod2" class="Hash">
        <property name="partitionCount">2</property>
        <property name="partitionLength">1</property>
    </function>

server.xml

steps：

step1. executing following command

delete from xa_test;
INSERT INTO xa_test (id) VALUES(1),(2),(3);
set xa=1;
delete from xa_test;

Before you execute delete from xa_test; the second time, set a break point in method com.actiontech.dble.backend.mysql.nio.handler.transaction.xa.XACommitNodesHandler#preparePhase

step2. kill connection manually to imitate the network failure

step3 check result of the second delete statement

• expect result：
  1. If the implicit transaction failed to commit and is rollbacked automatically
     (DML executed sucessfully but xa prepare run into network failure) , then error message that 【indicate the fact of auto-rollback behaviour】 and 【the real error message】 should be returned to the user.
• real result：
  1. It's OK Packet...
• supplements：
  1.

/label ~BUG

[tankilo]

The cause of the problem

XAAutoRollbackNodesHandler extends XARollbackNodesHandler, in XAAutoRollbackNodesHandler's constructor, the error that leads to automatic rollback operation is passed to XARollbackNodesHandler#sendData.

In XARollbackNodesHandler#cleanAndFeedback, when rollback opertaion executed successfully, the following logic doesn't consider the automatic rollback scene, it simplely return OK packet. In explicit transaction scene, this is reasonable, users get OK packet from their rollback statement. But in the case of implicit transaction with automatic rollback, the error that passed via XAAutoRollbackNodesHandler's constructor should be used. l think the error bytes should be decoded using the orginal charset and words that such as 'auto rollback happend, reason: ' should be added to the decoded error message.

[FlyingMao]

verified version： dble-9.9.9.9-3e92f5e5fde9cb9fb5b328c1d4fd2132e6232a7c-20190524070519