MW-416 DDL replication moved after acl checking

galera_events test shows a regression with the original fix for MW-416 Reason was that Events::drop_event() can be called also from inside event execution, and there we have a speacial treatment for event, which executes "DROP EVENT" statement, and runs TOI replication inside the event processing body. This resulted in executing WSREP_TO_ISOLATION two times for such DROP EVENT statement. Fix is to call WSREP_TO_ISOLATION_BEGIN only in Events::drop_event()

Author: sjaakola

sql/event_data_objects.cc

@@ -1472,19 +1472,33 @@ Event_job_data::execute(THD *thd, bool drop)
  bool save_tx_read_only= thd->tx_read_only;
  thd->tx_read_only= false;
 
- if (WSREP(thd))
- {
+ /*
+ This code is processing event execution and does not have client
+ connection. Here, event execution will now execute a prepared
+ DROP EVENT statement, but thd->lex->sql_command is set to
+ SQLCOM_CREATE_PROCEDURE
+ DROP EVENT will be logged in binlog, and we have to
+ replicate it to make all nodes have consistent event definitions
+ Wsrep DDL replication is triggered inside Events::drop_event(),
+ and here we need to prepare the THD so that DDL replication is
+ possible, essentially it requires setting sql_command to
+ SQLCOMM_DROP_EVENT, we will switch sql_command for the duration
+ of DDL replication only.
+ */
+ const enum_sql_command sql_command_save= thd->lex->sql_command;
+ const bool sql_command_set= WSREP(thd);
+
+ if (sql_command_set)
  thd->lex->sql_command = SQLCOM_DROP_EVENT;
- WSREP_TO_ISOLATION_BEGIN(WSREP_MYSQL_DB, NULL, NULL);
- }
 
  ret= Events::drop_event(thd, dbname, name, FALSE);
 
- WSREP_TO_ISOLATION_END;
+ if (sql_command_set)
+ {
+ WSREP_TO_ISOLATION_END;
+ thd->lex->sql_command = sql_command_save;
+ }
 
-#ifdef WITH_WSREP
- error:
-#endif
  thd->tx_read_only= save_tx_read_only;
  thd->security_ctx->master_access= saved_master_access;
  }