MDEV-21758 : Events switched randomly to SLAVESIDE_DISABLED

Change events only on Galera environment where idea is that
event is enabled only on one node of the cluster and nodes
are identified by server_id.

Author: Jan Lindström

mysql-test/r/events_restart.result

@@ -110,3 +110,30 @@ Db	Name	Definer	Time zone	Type	Execute at	Interval value	Interval field	Starts	E
 test	e1	root@localhost	SYSTEM	RECURRING	#	1	SECOND	#	#	DISABLED	1	latin1	latin1_swedish_ci	latin1_swedish_ci
 DROP EVENT e1;
 # end test for bug#11748899
+#
+# Test for MDEV-21758 Events switched randomly to SLAVESIDE_DISABLED
+#
+create event ev on schedule every 1 minute do set @a= 1;
+select name, originator, status from mysql.event;
+name	originator	status
+ev	1	ENABLED
+#
+# Restarting server with server_id=100
+#
+select @@global.server_id;
+@@global.server_id
+100
+select name, originator, status from mysql.event;
+name	originator	status
+ev	1	ENABLED
+set global server_id= 1;
+#
+# Restarting server with the original server_id=1
+#
+select @@global.server_id;
+@@global.server_id
+1
+select name, originator, status from mysql.event;
+name	originator	status
+ev	1	ENABLED
+drop event ev;

mysql-test/t/events_restart.test

@@ -141,3 +141,34 @@ SHOW EVENTS;
 DROP EVENT e1;
 
 --echo # end test for bug#11748899
+
+--echo #
+--echo # Test for MDEV-21758 Events switched randomly to SLAVESIDE_DISABLED
+--echo #
+
+create event ev on schedule every 1 minute do set @a= 1;
+select name, originator, status from mysql.event;
+
+--let $server_id= `SELECT @@global.server_id`
+
+--echo #
+--echo # Restarting server with server_id=100
+--echo #
+--let $restart_parameters= --server-id=100
+--source include/restart_mysqld.inc
+
+select @@global.server_id;
+select name, originator, status from mysql.event;
+--eval set global server_id= $server_id
+
+--echo #
+--echo # Restarting server with the original server_id=$server_id
+--echo #
+--let $restart_parameters=
+--source include/restart_mysqld.inc
+
+select @@global.server_id;
+select name, originator, status from mysql.event;
+
+# Cleanup
+drop event ev;

sql/events.cc

@@ -1201,9 +1201,9 @@ Events::load_events_from_db(THD *thd)
 
 #ifdef WITH_WSREP
     /**
-      IF SST is done from a galera node that is also acting as MASTER
-      newly synced node in galera eco-system will also copy-over the event state
-      enabling duplicate event in galera eco-system.
+      If SST is done from a galera node that is also acting as MASTER
+      newly synced node in galera eco-system will also copy-over the
+      event state enabling duplicate event in galera eco-system.
       DISABLE such events if the current node is not event orginator.
       (Also, make sure you skip disabling it if is already disabled to avoid
        creation of redundant action)
@@ -1213,7 +1213,7 @@ Events::load_events_from_db(THD *thd)
       Infact, based on galera use-case it seems like it recommends to have each
       node with different server-id.
     */
-    if (et->originator != thd->variables.server_id)
+    if (WSREP(thd) && et->originator != thd->variables.server_id)
     {
         if (et->status == Event_parse_data::SLAVESIDE_DISABLED)
           continue;