BUG#28908 Replication: set global server_id is not setting the session server_id

When set the server-id dynamically, the server_id member of current thread is not updated.

Update the server_id member of current thread after updated the global variable value.

mysql-test/r/rpl_server_id.result

+set global server_id=1;
+reset master;
+drop table if exists t1,t2,t3;
+create table t1 (a int);
+select @@server_id;
+@@server_id
+1
+show binlog events from <binlog_start>;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	#	Query	1	#	use `test`; drop table if exists t1,t2,t3
+master-bin.000001	#	Query	1	#	use `test`; create table t1 (a int)
+set global server_id=2;
+create table t2 (b int);
+select @@server_id;
+@@server_id
+2
+show binlog events from <binlog_start>;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	#	Query	1	#	use `test`; drop table if exists t1,t2,t3
+master-bin.000001	#	Query	1	#	use `test`; create table t1 (a int)
+master-bin.000001	#	Query	2	#	use `test`; create table t2 (b int)
+set global server_id=3;
+create table t3 (c int);
+select @@server_id;
+@@server_id
+3
+show binlog events from <binlog_start>;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	#	Query	1	#	use `test`; drop table if exists t1,t2,t3
+master-bin.000001	#	Query	1	#	use `test`; create table t1 (a int)
+master-bin.000001	#	Query	2	#	use `test`; create table t2 (b int)
+master-bin.000001	#	Query	3	#	use `test`; create table t3 (c int)
+set global server_id=1;
+drop table t1,t2,t3;

mysql-test/t/rpl_server_id.test

+# Test for BUG#28908 Replication: set global server_id is not setting the session server_id
+
+-- source include/have_log_bin.inc
+
+let $saved_server_id=`select @@server_id`;
+set global server_id=1;
+reset master;
+
+-- disable_warnings
+drop table if exists t1,t2,t3;
+-- enable_warnings
+
+create table t1 (a int);
+select @@server_id;
+source include/show_binlog_events2.inc;
+
+set global server_id=2;
+create table t2 (b int);
+select @@server_id;
+source include/show_binlog_events2.inc;
+
+set global server_id=3;
+create table t3 (c int);
+select @@server_id;
+source include/show_binlog_events2.inc;
+
+# cleanup
+eval set global server_id=$saved_server_id;
+drop table t1,t2,t3;

sql/set_var.cc

@@ -1441,6 +1441,7 @@ static void fix_trans_mem_root(THD *thd, enum_var_type type)
 static void fix_server_id(THD *thd, enum_var_type type)
 {
   server_id_supplied = 1;
+  thd->server_id= server_id;
 }