Postgres-xl GTM（全局事务管理器 Globale Transaction Manager）事务管理消息处理

系统管理员 2022-09-10 00:23 156阅读 0赞

消息处理API，由客户端通过网络连接GTM Master调用，这些消息处理API通过上述函数达到目的。

ProcessGetGIDDataTransactionCommand()  -->  MSG_TXN_GET_GID_DATA
    ProcessGXIDListCommand()  -->  MSG_TXN_GXID_LIST
    ProcessGetGXIDTransactionCommand()  -->  MSG_TXN_GET_GXID
    ProcessGetNextGXIDTransactionCommand()  -->  MSG_TXN_GET_NEXT_GXID
    ProcessReportXminCommand()
    
    ProcessBeginTransactionCommand()  -->  MSG_TXN_BEGIN message
    ProcessBeginTransactionGetGXIDCommand()  -->  MSG_TXN_BEGIN_GETGXID
    ProcessBeginTransactionGetGXIDAutovacuumCommand()  -->  MSG_TXN_BEGIN_GETGXID_AUTOVACUUM
    ProcessBeginTransactionGetGXIDCommandMulti()  -->  MSG_TXN_BEGIN_GETGXID_MULTI
    
    ProcessBkupBeginTransactionCommand()  -->  MSG_BKUP_TXN_BEGIN
    ProcessBkupBeginTransactionGetGXIDCommand()  -->  MSG_BKUP_TXN_BEGIN_GETGXID
    ProcessBkupBeginTransactionGetGXIDCommandMulti()  -->  MSG_BKUP_BEGIN_TXN_GETGXID_MULTI
    ProcessBkupBeginTransactionGetGXIDAutovacuumCommand()  -->  MSG_BKUP_TXN_BEGIN_GETGXID_AUTOVACUUM
    
    ProcessRollbackTransactionCommand()  -->  MSG_TXN_ROLLBACK/MSG_BKUP_TXN_ROLLBACK
    ProcessRollbackTransactionCommandMulti()  -->  MSG_TXN_ROLLBACK_MULTI/MSG_BKUP_TXN_ROLLBACK_MULTIMSG_TXN_COMMIT_MULTI/MSG_BKUP_TXN_COMMIT_MULTI
    
    ProcessCommitTransactionCommand()  -->  MSG_TXN_COMMIT/MSG_BKUP_TXN_COMMIT
    ProcessCommitTransactionCommandMulti()
    ProcessCommitPreparedTransactionCommand()  -->  MSG_TXN_COMMIT_PREPARED/MSG_BKUP_TXN_COMMIT_PREPARED
    
    ProcessPrepareTransactionCommand()  -->  MSG_TXN_PREPARE/MSG_BKUP_TXN_PREPARE
    ProcessStartPreparedTransactionCommand()  -->  MSG_TXN_START_PREPARED/MSG_BKUP_TXN_START_PREPARED

### BeginTransaction ###

ProcessBeginTransactionCommand()  -->  MSG_TXN_BEGIN message
    ProcessBeginTransactionGetGXIDCommand()  -->  MSG_TXN_BEGIN_GETGXID
    ProcessBeginTransactionGetGXIDAutovacuumCommand()  -->  MSG_TXN_BEGIN_GETGXID_AUTOVACUUM
    ProcessBeginTransactionGetGXIDCommandMulti()  -->  MSG_TXN_BEGIN_GETGXID_MULTI

ProcessBeginTransactionCommand函数的流程如下：从message中取出事务隔离级别、read only、session字符串，调用GTM\_BeginTransaction函数启动新事务，获取时间戳，调用bkup\_begin\_transaction向standby同步事务，填充返回消息并将消息返回。

ProcessBeginTransactionGetGXIDCommand函数的流程如下：从message中取出事务隔离级别、read only、session字符串，获取时间戳，调用GTM\_BeginTransaction函数启动新事务，**调用GTM\_GetGlobalTransactionId函数获取全局事务ID**，调用bkup\_begin\_transaction\_gxid向standby同步事务，填充返回消息并将消息返回。

ProcessBeginTransactionGetGXIDAutovacuumCommand函数取出事务隔离级别、txn client id，调用GTM\_BeginTransaction函数启动新事务，**调用GTM\_GetGlobalTransactionId函数获取全局事务ID**，调用GTM\_SetDoVacuum函数，调用bkup\_begin\_transaction\_autovacuum向standby同步事务，填充返回消息并将消息返回。

ProcessBeginTransactionGetGXIDCommandMulti函数先获取请求事务数、再循环获取事务隔离级别、read only、session字符串，txn client id，调用GTM\_BeginTransactionMulti，获取时间戳，调用bkup\_begin\_transaction\_multi向standby同步事务，填充返回消息并将消息返回。

ProcessBkupBeginTransactionCommand()  -->  MSG_BKUP_TXN_BEGIN
    ProcessBkupBeginTransactionGetGXIDCommand()  -->  MSG_BKUP_TXN_BEGIN_GETGXID
    ProcessBkupBeginTransactionGetGXIDCommandMulti()  -->  MSG_BKUP_BEGIN_TXN_GETGXID_MULTI
    ProcessBkupBeginTransactionGetGXIDAutovacuumCommand()  -->  MSG_BKUP_TXN_BEGIN_GETGXID_AUTOVACUUM

ProcessBkupBeginTransactionCommand函数从message中取出事务隔离级别、read only、session字符串、client id，调用GTM\_BkupBeginTransaction函数。

ProcessBkupBeginTransactionGetGXIDCommand函数取出事务隔离级别、read only、session字符串、txn client id，调用GTM\_BkupBeginTransactionGetGXID函数。

ProcessBkupBeginTransactionGetGXIDCommandMulti先获取请求事务数、再循环获取事务隔离级别、read only、session字符串，txn client id，调用GTM\_BkupBeginTransactionGetGXIDMulti函数。

ProcessBkupBeginTransactionGetGXIDAutovacuumCommand函数取出事务隔离级别、txn client id，调用GTM\_BkupBeginTransactionGetGXID函数，调用GTM\_SetDoVacuum函数。

### CommitTransaction ###

ProcessCommitTransactionCommand()  -->  MSG_TXN_COMMIT/MSG_BKUP_TXN_COMMIT
    ProcessCommitTransactionCommandMulti()
    ProcessCommitPreparedTransactionCommand()  -->  MSG_TXN_COMMIT_PREPARED/MSG_BKUP_TXN_COMMIT_PREPARED

ProcessCommitTransactionCommand函数从消息中获取gxid，通过GTM\_GXIDToHandle(gxid)获取事务句柄，然后从消息中获取等待xid的数量，获取其等待的所有xid，调用GTM\_CommitTransaction函数，调用bkup\_commit\_transaction向standby同步事务，填充返回消息并将消息返回。

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ProcessCommitPreparedTransactionCommand函数