MDEV-5804: If same GTID is received on multiple master connections in multi-source replication, the event is double-executed causing corruption or replication failure

Before, the arrival of same GTID twice in multi-source replication
would cause double-apply or in gtid strict mode an error.

Keep the behaviour, but add an option --gtid-ignore-duplicates which
allows to correctly handle duplicates, ignoring all but the first.
This relies on the user ensuring correct configuration so that
sequence numbers are strictly increasing within each replication
domain; then duplicates can be detected simply by comparing the
sequence numbers against what is already applied.

Only one master connection (but possibly multiple parallel worker
threads within that connection) is allowed to apply events within
one replication domain at a time; any other connection that
receives a GTID in the same domain either discards it (if it is
already applied) or waits for the other connection to not have
any events to apply.

Intermediate patch, as proof-of-concept for testing. The main limitation
is that currently it is only implemented for parallel replication,
@@slave_parallel_threads > 0.

3 files changed, 420 insertions, 0 deletions

diff --git a/mysql-test/suite/multi_source/gtid_ignore_duplicates.cnf b/mysql-test/suite/multi_source/gtid_ignore_duplicates.cnf
new file mode 100644
index 00000000000..b47ebb2cf30
--- /dev/null
+++ b/mysql-test/suite/multi_source/gtid_ignore_duplicates.cnf
@@ -0,0 +1,24 @@
+!include my.cnf
+
+[mysqld.1]
+log-slave-updates
+loose-innodb
+
+[mysqld.2]
+log-slave-updates
+loose-innodb
+
+[mysqld.3]
+log-bin=server3-bin
+log-slave-updates
+loose-innodb
+
+[mysqld.4]
+server-id=4
+log-bin=server4-bin
+log-slave-updates
+loose-innodb
+
+[ENV]
+SERVER_MYPORT_4=		@mysqld.4.port
+SERVER_MYSOCK_4=		@mysqld.4.socket
diff --git a/mysql-test/suite/multi_source/gtid_ignore_duplicates.result b/mysql-test/suite/multi_source/gtid_ignore_duplicates.result
new file mode 100644
index 00000000000..bac522af76b
--- /dev/null
+++ b/mysql-test/suite/multi_source/gtid_ignore_duplicates.result
@@ -0,0 +1,188 @@
+*** Test all-to-all replication with --gtid-ignore-duplicates ***
+SET @old_parallel= @@GLOBAL.slave_parallel_threads;
+SET GLOBAL slave_parallel_threads=5;
+SET @old_ignore_duplicates= @@GLOBAL.gtid_ignore_duplicates;
+SET GLOBAL gtid_ignore_duplicates=1;
+SET GLOBAL gtid_domain_id= 1;
+SET SESSION gtid_domain_id= 1;
+CHANGE MASTER 'b2a' TO master_port=MYPORT_2, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+CHANGE MASTER 'c2a' TO master_port=MYPORT_3, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+set default_master_connection = 'b2a';
+START SLAVE;
+include/wait_for_slave_to_start.inc
+set default_master_connection = 'c2a';
+START SLAVE;
+include/wait_for_slave_to_start.inc
+set default_master_connection = '';
+SET @old_parallel= @@GLOBAL.slave_parallel_threads;
+SET GLOBAL slave_parallel_threads=5;
+SET @old_ignore_duplicates= @@GLOBAL.gtid_ignore_duplicates;
+SET GLOBAL gtid_ignore_duplicates=1;
+SET GLOBAL gtid_domain_id= 2;
+SET SESSION gtid_domain_id= 2;
+CHANGE MASTER 'a2b' TO master_port=MYPORT_1, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+CHANGE MASTER 'c2b' TO master_port=MYPORT_3, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+set default_master_connection = 'a2b';
+START SLAVE;
+include/wait_for_slave_to_start.inc
+set default_master_connection = 'c2b';
+START SLAVE;
+include/wait_for_slave_to_start.inc
+set default_master_connection = '';
+SET @old_parallel= @@GLOBAL.slave_parallel_threads;
+SET GLOBAL slave_parallel_threads=5;
+SET @old_ignore_duplicates= @@GLOBAL.gtid_ignore_duplicates;
+SET GLOBAL gtid_ignore_duplicates=1;
+SET GLOBAL gtid_domain_id= 3;
+SET SESSION gtid_domain_id= 3;
+CHANGE MASTER 'a2c' TO master_port=MYPORT_1, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+CHANGE MASTER 'b2c' TO master_port=MYPORT_2, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+set default_master_connection = 'a2c';
+START SLAVE;
+include/wait_for_slave_to_start.inc
+set default_master_connection = 'b2c';
+START SLAVE;
+include/wait_for_slave_to_start.inc
+set default_master_connection = '';
+SET @old_parallel= @@GLOBAL.slave_parallel_threads;
+SET GLOBAL slave_parallel_threads=5;
+SET @old_ignore_duplicates= @@GLOBAL.gtid_ignore_duplicates;
+SET GLOBAL gtid_ignore_duplicates=1;
+SET GLOBAL gtid_domain_id= 1;
+SET SESSION gtid_domain_id= 1;
+CHANGE MASTER 'a2d' TO master_port=MYPORT_1, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+set default_master_connection = 'a2d';
+START SLAVE;
+include/wait_for_slave_to_start.inc
+set default_master_connection = '';
+ALTER TABLE mysql.gtid_slave_pos ENGINE=InnoDB;
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1);
+BEGIN;
+INSERT INTO t1 VALUES (2);
+INSERT INTO t1 VALUES (3);
+COMMIT;
+INSERT INTO t1 VALUES (4), (5);
+INSERT INTO t1 VALUES (6);
+include/save_master_gtid.inc
+include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+a
+1
+2
+3
+4
+5
+6
+include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+a
+1
+2
+3
+4
+5
+6
+include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+a
+1
+2
+3
+4
+5
+6
+include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+a
+1
+2
+3
+4
+5
+6
+INSERT INTO t1 VALUES (10);
+include/save_master_gtid.inc
+include/sync_with_master_gtid.inc
+SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
+a
+10
+STOP SLAVE "c2b";
+SET default_master_connection = "c2b";
+include/wait_for_slave_to_stop.inc
+STOP SLAVE "a2b";
+SET default_master_connection = "a2b";
+include/wait_for_slave_to_stop.inc
+INSERT INTO t1 VALUES (11);
+include/save_master_gtid.inc
+include/sync_with_master_gtid.inc
+SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
+a
+10
+11
+SET default_master_connection = "b2a";
+STOP SLAVE;
+include/wait_for_slave_to_stop.inc
+INSERT INTO t1 VALUES (12);
+SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
+a
+10
+12
+include/save_master_gtid.inc
+START SLAVE "b2a";
+SET default_master_connection = "b2a";
+include/wait_for_slave_to_start.inc
+include/sync_with_master_gtid.inc
+SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
+a
+10
+11
+12
+START SLAVE "c2b";
+SET default_master_connection = "c2b";
+include/wait_for_slave_to_start.inc
+START SLAVE "a2b";
+SET default_master_connection = "a2b";
+include/wait_for_slave_to_start.inc
+include/save_master_gtid.inc
+include/sync_with_master_gtid.inc
+SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
+a
+10
+11
+12
+SET GLOBAL gtid_domain_id=0;
+STOP ALL SLAVES;
+Warnings:
+Note	1938	SLAVE 'c2a' stopped
+Note	1938	SLAVE 'b2a' stopped
+include/reset_master_slave.inc
+SET GLOBAL slave_parallel_threads= @old_parallel;
+SET GLOBAL gtid_ignore_duplicates= @old_ignore_duplicates;
+DROP TABLE t1;
+SET GLOBAL gtid_domain_id=0;
+STOP ALL SLAVES;
+Warnings:
+Note	1938	SLAVE 'a2b' stopped
+Note	1938	SLAVE 'c2b' stopped
+include/reset_master_slave.inc
+SET GLOBAL slave_parallel_threads= @old_parallel;
+SET GLOBAL gtid_ignore_duplicates= @old_ignore_duplicates;
+DROP TABLE t1;
+SET GLOBAL gtid_domain_id=0;
+STOP ALL SLAVES;
+Warnings:
+Note	1938	SLAVE 'a2c' stopped
+Note	1938	SLAVE 'b2c' stopped
+include/reset_master_slave.inc
+SET GLOBAL slave_parallel_threads= @old_parallel;
+SET GLOBAL gtid_ignore_duplicates= @old_ignore_duplicates;
+DROP TABLE t1;
+SET GLOBAL gtid_domain_id=0;
+STOP ALL SLAVES;
+Warnings:
+Note	1938	SLAVE 'a2d' stopped
+include/reset_master_slave.inc
+SET GLOBAL slave_parallel_threads= @old_parallel;
+SET GLOBAL gtid_ignore_duplicates= @old_ignore_duplicates;
+DROP TABLE t1;
diff --git a/mysql-test/suite/multi_source/gtid_ignore_duplicates.test b/mysql-test/suite/multi_source/gtid_ignore_duplicates.test
new file mode 100644
index 00000000000..16db4d82ddd
--- /dev/null
+++ b/mysql-test/suite/multi_source/gtid_ignore_duplicates.test
@@ -0,0 +1,208 @@
+--source include/not_embedded.inc
+--source include/have_innodb.inc
+
+--echo *** Test all-to-all replication with --gtid-ignore-duplicates ***
+
+--connect (server_1,127.0.0.1,root,,,$SERVER_MYPORT_1)
+--connect (server_2,127.0.0.1,root,,,$SERVER_MYPORT_2)
+--connect (server_3,127.0.0.1,root,,,$SERVER_MYPORT_3)
+--connect (server_4,127.0.0.1,root,,,$SERVER_MYPORT_4)
+
+# Setup A <-> B, B <-> C, C <-> A, and A -> D.
+
+--connection server_1
+SET @old_parallel= @@GLOBAL.slave_parallel_threads;
+SET GLOBAL slave_parallel_threads=5;
+SET @old_ignore_duplicates= @@GLOBAL.gtid_ignore_duplicates;
+SET GLOBAL gtid_ignore_duplicates=1;
+SET GLOBAL gtid_domain_id= 1;
+SET SESSION gtid_domain_id= 1;
+--replace_result $SERVER_MYPORT_2 MYPORT_2
+eval CHANGE MASTER 'b2a' TO master_port=$SERVER_MYPORT_2, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+--replace_result $SERVER_MYPORT_3 MYPORT_3
+eval CHANGE MASTER 'c2a' TO master_port=$SERVER_MYPORT_3, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+set default_master_connection = 'b2a';
+START SLAVE;
+--source include/wait_for_slave_to_start.inc
+set default_master_connection = 'c2a';
+START SLAVE;
+--source include/wait_for_slave_to_start.inc
+set default_master_connection = '';
+
+--connection server_2
+SET @old_parallel= @@GLOBAL.slave_parallel_threads;
+SET GLOBAL slave_parallel_threads=5;
+SET @old_ignore_duplicates= @@GLOBAL.gtid_ignore_duplicates;
+SET GLOBAL gtid_ignore_duplicates=1;
+SET GLOBAL gtid_domain_id= 2;
+SET SESSION gtid_domain_id= 2;
+--replace_result $SERVER_MYPORT_1 MYPORT_1
+eval CHANGE MASTER 'a2b' TO master_port=$SERVER_MYPORT_1, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+--replace_result $SERVER_MYPORT_3 MYPORT_3
+eval CHANGE MASTER 'c2b' TO master_port=$SERVER_MYPORT_3, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+set default_master_connection = 'a2b';
+START SLAVE;
+--source include/wait_for_slave_to_start.inc
+set default_master_connection = 'c2b';
+START SLAVE;
+--source include/wait_for_slave_to_start.inc
+set default_master_connection = '';
+
+--connection server_3
+SET @old_parallel= @@GLOBAL.slave_parallel_threads;
+SET GLOBAL slave_parallel_threads=5;
+SET @old_ignore_duplicates= @@GLOBAL.gtid_ignore_duplicates;
+SET GLOBAL gtid_ignore_duplicates=1;
+SET GLOBAL gtid_domain_id= 3;
+SET SESSION gtid_domain_id= 3;
+--replace_result $SERVER_MYPORT_1 MYPORT_1
+eval CHANGE MASTER 'a2c' TO master_port=$SERVER_MYPORT_1, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+--replace_result $SERVER_MYPORT_2 MYPORT_2
+eval CHANGE MASTER 'b2c' TO master_port=$SERVER_MYPORT_2, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+set default_master_connection = 'a2c';
+START SLAVE;
+--source include/wait_for_slave_to_start.inc
+set default_master_connection = 'b2c';
+START SLAVE;
+--source include/wait_for_slave_to_start.inc
+set default_master_connection = '';
+
+--connection server_4
+SET @old_parallel= @@GLOBAL.slave_parallel_threads;
+SET GLOBAL slave_parallel_threads=5;
+SET @old_ignore_duplicates= @@GLOBAL.gtid_ignore_duplicates;
+SET GLOBAL gtid_ignore_duplicates=1;
+SET GLOBAL gtid_domain_id= 1;
+SET SESSION gtid_domain_id= 1;
+--replace_result $SERVER_MYPORT_1 MYPORT_1
+eval CHANGE MASTER 'a2d' TO master_port=$SERVER_MYPORT_1, master_host='127.0.0.1', master_user='root', master_use_gtid=slave_pos;
+set default_master_connection = 'a2d';
+START SLAVE;
+--source include/wait_for_slave_to_start.inc
+set default_master_connection = '';
+
+
+--connection server_1
+ALTER TABLE mysql.gtid_slave_pos ENGINE=InnoDB;
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1);
+BEGIN;
+INSERT INTO t1 VALUES (2);
+INSERT INTO t1 VALUES (3);
+COMMIT;
+INSERT INTO t1 VALUES (4), (5);
+INSERT INTO t1 VALUES (6);
+
+--source include/save_master_gtid.inc
+
+--connection server_2
+--source include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+
+--connection server_3
+--source include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+
+--connection server_4
+--source include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+
+--connection server_1
+--source include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+
+# Test that we can connect at a GTID position that has not yet reached
+# that master server.
+# We stop the connections C->B and A->B, create an event on C, Check that
+# the event has reached A (but not B). Then let A stop and re-connect to
+# B, which will connect at the new event, which is in the future for B.
+
+--connection server_3
+INSERT INTO t1 VALUES (10);
+--source include/save_master_gtid.inc
+
+--connection server_2
+--source include/sync_with_master_gtid.inc
+SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
+STOP SLAVE "c2b";
+SET default_master_connection = "c2b";
+--source include/wait_for_slave_to_stop.inc
+STOP SLAVE "a2b";
+SET default_master_connection = "a2b";
+--source include/wait_for_slave_to_stop.inc
+
+--connection server_3
+INSERT INTO t1 VALUES (11);
+--source include/save_master_gtid.inc
+
+--connection server_1
+--source include/sync_with_master_gtid.inc
+SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
+SET default_master_connection = "b2a";
+STOP SLAVE;
+--source include/wait_for_slave_to_stop.inc
+
+--connection server_2
+INSERT INTO t1 VALUES (12);
+SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
+--source include/save_master_gtid.inc
+
+--connection server_1
+START SLAVE "b2a";
+SET default_master_connection = "b2a";
+--source include/wait_for_slave_to_start.inc
+--source include/sync_with_master_gtid.inc
+SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
+
+--connection server_2
+START SLAVE "c2b";
+SET default_master_connection = "c2b";
+--source include/wait_for_slave_to_start.inc
+START SLAVE "a2b";
+SET default_master_connection = "a2b";
+--source include/wait_for_slave_to_start.inc
+
+--connection server_1
+--source include/save_master_gtid.inc
+
+--connection server_2
+--source include/sync_with_master_gtid.inc
+SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
+
+
+# Clean up.
+--connection server_1
+SET GLOBAL gtid_domain_id=0;
+STOP ALL SLAVES;
+--source reset_master_slave.inc
+SET GLOBAL slave_parallel_threads= @old_parallel;
+SET GLOBAL gtid_ignore_duplicates= @old_ignore_duplicates;
+DROP TABLE t1;
+--disconnect server_1
+
+--connection server_2
+SET GLOBAL gtid_domain_id=0;
+STOP ALL SLAVES;
+--source reset_master_slave.inc
+SET GLOBAL slave_parallel_threads= @old_parallel;
+SET GLOBAL gtid_ignore_duplicates= @old_ignore_duplicates;
+DROP TABLE t1;
+--disconnect server_2
+
+--connection server_3
+SET GLOBAL gtid_domain_id=0;
+STOP ALL SLAVES;
+--source reset_master_slave.inc
+SET GLOBAL slave_parallel_threads= @old_parallel;
+SET GLOBAL gtid_ignore_duplicates= @old_ignore_duplicates;
+DROP TABLE t1;
+--disconnect server_3
+
+--connection server_4
+SET GLOBAL gtid_domain_id=0;
+STOP ALL SLAVES;
+--source reset_master_slave.inc
+SET GLOBAL slave_parallel_threads= @old_parallel;
+SET GLOBAL gtid_ignore_duplicates= @old_ignore_duplicates;
+DROP TABLE t1;
+--disconnect server_4