MDEV-26: Global transaction ID.

Fix MDEV-4278: Slave does not check that master understands GTID.

Now the slave will abort with a suitable error if an attempt is made to connect
with GTID to a master that does not support GTID.

mysql-test/suite/rpl/r/rpl_gtid_errorhandling.result

@@ -73,5 +73,17 @@ a
 3
 4
 5
+*** MDEV-4278: Slave does not detect that master is not GTID-aware ***
+include/stop_slave.inc
+SET @old_dbug= @@global.DEBUG_DBUG;
+SET GLOBAL debug_dbug="+d,simulate_non_gtid_aware_master";
+START SLAVE;
+include/wait_for_slave_io_error.inc [errno=1233]
+SET GLOBAL debug_dbug= @old_dbug;
+INSERT INTO t1 VALUES (6);
+START SLAVE;
+SET sql_log_bin=0;
+CALL mtr.add_suppression("The slave I/O thread stops because master does not support MariaDB global transaction id");
+SET sql_log_bin=1;
 DROP TABLE t1;
 include/rpl_end.inc

mysql-test/suite/rpl/t/rpl_gtid_errorhandling.test

@@ -107,6 +107,33 @@ INSERT INTO t1 VALUES (5);
 SELECT * FROM t1 ORDER BY a;
 
 
+--echo *** MDEV-4278: Slave does not detect that master is not GTID-aware ***
+
+--connection slave
+--source include/stop_slave.inc
+
+--connection master
+SET @old_dbug= @@global.DEBUG_DBUG;
+SET GLOBAL debug_dbug="+d,simulate_non_gtid_aware_master";
+
+--connection slave
+START SLAVE;
+--let $slave_io_errno= 1233
+--source include/wait_for_slave_io_error.inc
+
+--connection master
+SET GLOBAL debug_dbug= @old_dbug;
+INSERT INTO t1 VALUES (6);
+--save_master_pos
+
+--connection slave
+START SLAVE;
+--sync_with_master
+SET sql_log_bin=0;
+CALL mtr.add_suppression("The slave I/O thread stops because master does not support MariaDB global transaction id");
+SET sql_log_bin=1;
+
+
 --connection master
 DROP TABLE t1;
 

sql/item_func.cc

@@ -5678,6 +5678,14 @@ longlong Item_func_get_system_var::val_int()
 {
   THD *thd= current_thd;
 
+  DBUG_EXECUTE_IF("simulate_non_gtid_aware_master",
+                  {
+                    if (0 == strcmp("gtid_domain_id", var->name.str))
+                    {
+                      my_error(ER_VAR_CANT_BE_READ, MYF(0), var->name.str);
+                      return 0;
+                    }
+                  });
   if (cache_present && thd->query_id == used_query_id)
   {
     if (cache_present & GET_SYS_VAR_CACHE_LONG)

sql/slave.cc

@@ -1823,6 +1823,27 @@ after_set_capability:
     rpl_gtid *binlog_gtid_list= NULL;
     uint32 num_binlog_gtids= 0;
 
+    /*
+      Read the master @@GLOBAL.gtid_domain_id variable.
+      This is mostly to check that master is GTID aware, but we could later
+      perhaps use it to check that different multi-source masters are correctly
+      configured with distinct domain_id.
+    */
+    if (mysql_real_query(mysql,
+                         STRING_WITH_LEN("SELECT @@GLOBAL.gtid_domain_id")) ||
+        !(master_res= mysql_store_result(mysql)) ||
+        !(master_row= mysql_fetch_row(master_res)))
+    {
+      err_code= mysql_errno(mysql);
+      errmsg= "The slave I/O thread stops because master does not support "
+        "MariaDB global transaction id. A fatal error is encountered when "
+        "it tries to SELECT @@GLOBAL.gtid_domain_id.";
+      sprintf(err_buff, "%s Error: %s", errmsg, mysql_error(mysql));
+      goto err;
+    }
+    mysql_free_result(master_res);
+    master_res= NULL;
+
     if (opt_bin_log)
     {
       int err= mysql_bin_log.get_most_recent_gtid_list(&binlog_gtid_list,

sql/sql_repl.cc

@@ -1419,6 +1419,7 @@ void mysql_binlog_send(THD* thd, char* log_ident, my_off_t pos,
 
   connect_gtid_state.length(0);
   using_gtid_state= get_slave_connect_state(thd, &connect_gtid_state);
+  DBUG_EXECUTE_IF("simulate_non_gtid_aware_master", using_gtid_state= false;);
 
   if (global_system_variables.log_warnings > 1)
     sql_print_information("Start binlog_dump to slave_server(%d), pos(%s, %lu)",