MDEV-26: Global transaction ID.

Fix MDEV-4275 - I/O thread restart duplicates events in the relay log.
The first time we connect to master after CHANGE MASTER or restart, we connect
from the GTID position. But then subsequent reconnects or IO thread restarts
reconnect with the old-style file/offset binlog pos from where it left off at
last disconnect. This is necessary to avoid duplicate events in the relay
logs, as there is nothing that synchronises the SQL thread update of GTID
state (multiple threads in case of multi-source) with IO thread reconnects.

Test cases.

Some small cleanups and fixes.

3 files changed, 118 insertions, 1 deletions

diff --git a/mysql-test/suite/rpl/t/rpl_gtid_crash-master.opt b/mysql-test/suite/rpl/t/rpl_gtid_crash-master.opt
new file mode 100644
index 00000000000..425fda95086
--- /dev/null
+++ b/mysql-test/suite/rpl/t/rpl_gtid_crash-master.opt
@@ -0,0 +1 @@
+--skip-stack-trace --skip-core-file
diff --git a/mysql-test/suite/rpl/t/rpl_gtid_crash.test b/mysql-test/suite/rpl/t/rpl_gtid_crash.test
new file mode 100644
index 00000000000..7f0413bfb6c
--- /dev/null
+++ b/mysql-test/suite/rpl/t/rpl_gtid_crash.test
@@ -0,0 +1,71 @@
+--source include/have_innodb.inc
+--let $rpl_topology=1->2
+--source include/rpl_init.inc
+
+--echo *** Test crashing master, causing slave IO thread to reconnect while SQL thread is running ***
+
+--connection server_1
+CREATE TABLE t1 (a INT PRIMARY KEY, b INT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1, 0);
+--save_master_pos
+
+--connection server_2
+--sync_with_master
+--source include/stop_slave.inc
+--replace_result $MASTER_MYPORT MASTER_PORT
+eval CHANGE MASTER TO master_host = '127.0.0.1', master_port = $MASTER_MYPORT,
+     MASTER_GTID_POS=AUTO;
+
+--connection server_1
+INSERT INTO t1 VALUES (2,1);
+INSERT INTO t1 VALUES (3,1);
+
+--connection server_2
+--source include/start_slave.inc
+
+--connection server_1
+
+--write_file $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+wait-rpl_gtid_crash.test
+EOF
+
+let $1=200;
+--disable_query_log
+while ($1)
+{
+  eval INSERT INTO t1 VALUES ($1 + 10, 2);
+  dec $1;
+}
+--enable_query_log
+
+SET SESSION debug_dbug="+d,crash_dispatch_command_before";
+--error 2006,2013
+SELECT 1;
+
+--remove_file $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+--write_file $MYSQLTEST_VARDIR/tmp/mysqld.1.expect
+restart-rpl_gtid_crash.test
+EOF
+
+--enable_reconnect
+--source include/wait_until_connected_again.inc
+
+--connection server_2
+--let $wait_condition= SELECT COUNT(*) = 200 FROM t1 WHERE b=2
+--source include/wait_condition.inc
+
+--connection server_1
+INSERT INTO t1 VALUES (1000, 3);
+
+--connection server_2
+--let $wait_condition= SELECT COUNT(*) = 1 FROM t1 WHERE b=3
+--source include/wait_condition.inc
+
+--connection server_1
+DROP TABLE t1;
+
+--connection default
+--enable_reconnect
+--source include/wait_until_connected_again.inc
+
+--source include/rpl_end.inc
diff --git a/mysql-test/suite/rpl/t/rpl_gtid_startpos.test b/mysql-test/suite/rpl/t/rpl_gtid_startpos.test
index 58f93ba6c54..32fb608080c 100644
--- a/mysql-test/suite/rpl/t/rpl_gtid_startpos.test
+++ b/mysql-test/suite/rpl/t/rpl_gtid_startpos.test
@@ -98,9 +98,54 @@ START SLAVE;
 --source include/wait_condition.inc
 SELECT * FROM t1 ORDER by a;
 
-# Clean up.
+--connection server_1
+DROP TABLE t1;
+--save_master_pos
+
+--connection server_2
+--sync_with_master
+
+
+--echo *** MDEV-4275: I/O thread restart duplicates events in relay log ***
+
+--connection server_2
+--source include/stop_slave.inc
+RESET SLAVE ALL;
+RESET MASTER;
+
+--connection server_1
+RESET MASTER;
+
+--connection server_2
+--replace_result $MASTER_MYPORT MASTER_PORT
+eval CHANGE MASTER TO master_host='127.0.0.1', master_port=$MASTER_MYPORT, master_user='root', master_gtid_pos='';
+--source include/start_slave.inc
 
 --connection server_1
+CREATE TABLE t1 (a INT PRIMARY KEY);
+INSERT INTO t1 VALUES (1);
+--save_master_pos
+
+--connection server_2
+--sync_with_master
+SELECT * FROM t1;
+
+--source include/stop_slave_io.inc
+START SLAVE IO_THREAD;
+--source include/wait_for_slave_io_to_start.inc
+
+--connection server_1
+INSERT INTO t1 VALUES (2);
+--save_master_pos
+
+--connection server_2
+--sync_with_master
+
+SELECT * FROM t1 ORDER BY a;
+
+# Clean up.
+--connection server_1
 DROP TABLE t1;
 
+
 --source include/rpl_end.inc