MDEV-35019 Provide a way to enable "rollback XA on disconnect" behavior we had before 10.5.2

Implement variable legacy_xa_rollback_at_disconnect to support
backwards compatibility for applications that rely on the pre-10.5
behavior for connection disconnect, which is to rollback the
transaction (in violation of the XA specification).

Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>

mysql-test/main/mysqld--help.result

@@ -433,6 +433,13 @@ The following specify which files/extra groups are read (specified before remain
  --lc-time-names=name 
  Set the language used for the month names and the days of
  the week.
+ --legacy-xa-rollback-at-disconnect 
+ If a user session disconnects after putting a transaction
+ into the XA PREPAREd state, roll back the transaction.
+ Can be used for backwards compatibility to enable this
+ pre-10.5 behavior for applications that expect it. Note
+ that this violates the XA specification and should not be
+ used for new code
  --local-infile      Enable LOAD DATA LOCAL INFILE
  (Defaults to on; use --skip-local-infile to disable.)
  --lock-wait-timeout=# 
@@ -1572,6 +1579,7 @@ large-pages FALSE
 lc-messages en_US
 lc-messages-dir MYSQL_SHAREDIR/
 lc-time-names en_US
+legacy-xa-rollback-at-disconnect FALSE
 local-infile TRUE
 lock-wait-timeout 86400
 log-bin foo

mysql-test/main/xa.result

@@ -592,6 +592,22 @@ formatID	gtrid_length	bqual_length	data
 xa rollback '4';
 ERROR XA100: XA_RBROLLBACK: Transaction branch was rolled back
 set @@global.read_only=@sav_read_only;
+# MDEV-35019: Provide a way to enable "rollback XA on disconnect" behavior we had before 10.5.2
+# Test legacy_xa_rollback_at_disconnect option.
+CREATE TABLE t1 (a INT PRIMARY KEY, b INT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1, 0);
+connect  con1,localhost,root,,;
+SET SESSION legacy_xa_rollback_at_disconnect= 1;
+XA START '5';
+INSERT INTO t1 VALUES (2, 0);
+XA END '5';
+XA PREPARE '5';
+disconnect con1;
+connection default;
+INSERT INTO t1 VALUES (3, 0);
+XA ROLLBACK '5';
+ERROR XAE04: XAER_NOTA: Unknown XID
+DROP TABLE t1;
 #
 # End of 10.5 tests
 #

mysql-test/main/xa.test

@@ -747,6 +747,25 @@ xa rollback '4';
 set @@global.read_only=@sav_read_only;
 
 
+--echo # MDEV-35019: Provide a way to enable "rollback XA on disconnect" behavior we had before 10.5.2
+--echo # Test legacy_xa_rollback_at_disconnect option.
+CREATE TABLE t1 (a INT PRIMARY KEY, b INT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1, 0);
+connect (con1,localhost,root,,);
+SET SESSION legacy_xa_rollback_at_disconnect= 1;
+XA START '5';
+INSERT INTO t1 VALUES (2, 0);
+XA END '5';
+XA PREPARE '5';
+disconnect con1;
+
+connection default;
+--source include/wait_until_count_sessions.inc
+INSERT INTO t1 VALUES (3, 0);
+--error ER_XAER_NOTA
+XA ROLLBACK '5';
+DROP TABLE t1;
+
 --echo #
 --echo # End of 10.5 tests
 --echo #

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

@@ -280,4 +280,28 @@ disconnect con1;
 connection master;
 xa commit '1';
 drop table t2, t1;
+# MDEV-35019 Provide a way to enable "rollback XA on disconnect" behavior we had before 10.5.2
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1), (3);
+connect con1, localhost,root;
+SET SESSION legacy_xa_rollback_at_disconnect= 1;
+XA START '3';
+INSERT INTO t1 VALUES (2);
+XA END '3';
+XA PREPARE '3';
+disconnect con1;
+connection master;
+include/save_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+a
+1
+3
+connection slave;
+include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+a
+1
+3
+connection master;
+DROP TABLE t1;
 include/rpl_end.inc

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

@@ -289,6 +289,30 @@ disconnect con1;
 connection master;
 xa commit '1';
 drop table t2, t1;
+# MDEV-35019 Provide a way to enable "rollback XA on disconnect" behavior we had before 10.5.2
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1), (3);
+connect con1, localhost,root;
+SET SESSION legacy_xa_rollback_at_disconnect= 1;
+XA START '3';
+INSERT INTO t1 VALUES (2);
+XA END '3';
+XA PREPARE '3';
+disconnect con1;
+connection master;
+include/save_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+a
+1
+3
+connection slave;
+include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+a
+1
+3
+connection master;
+DROP TABLE t1;
 connection slave;
 include/stop_slave.inc
 SET @@global.gtid_pos_auto_engines="";

mysql-test/suite/rpl/t/rpl_xa.inc

@@ -434,3 +434,26 @@ disconnect con1;
 connection master;
 xa commit '1';
 drop table t2, t1;
+
+--echo # MDEV-35019 Provide a way to enable "rollback XA on disconnect" behavior we had before 10.5.2
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1), (3);
+
+connect con1, localhost,root;
+SET SESSION legacy_xa_rollback_at_disconnect= 1;
+XA START '3';
+INSERT INTO t1 VALUES (2);
+XA END '3';
+XA PREPARE '3';
+--disconnect con1
+
+--connection master
+--source include/save_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+
+--connection slave
+--source include/sync_with_master_gtid.inc
+SELECT * FROM t1 ORDER BY a;
+
+--connection master
+DROP TABLE t1;

mysql-test/suite/sys_vars/r/sysvars_server_embedded.result

@@ -1532,6 +1532,16 @@ NUMERIC_BLOCK_SIZE	NULL
 ENUM_VALUE_LIST	NULL
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	NULL
+VARIABLE_NAME	LEGACY_XA_ROLLBACK_AT_DISCONNECT
+VARIABLE_SCOPE	SESSION
+VARIABLE_TYPE	BOOLEAN
+VARIABLE_COMMENT	If a user session disconnects after putting a transaction into the XA PREPAREd state, roll back the transaction. Can be used for backwards compatibility to enable this pre-10.5 behavior for applications that expect it. Note that this violates the XA specification and should not be used for new code
+NUMERIC_MIN_VALUE	NULL
+NUMERIC_MAX_VALUE	NULL
+NUMERIC_BLOCK_SIZE	NULL
+ENUM_VALUE_LIST	OFF,ON
+READ_ONLY	NO
+COMMAND_LINE_ARGUMENT	OPTIONAL
 VARIABLE_NAME	LICENSE
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	VARCHAR

mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result

@@ -1642,6 +1642,16 @@ NUMERIC_BLOCK_SIZE	NULL
 ENUM_VALUE_LIST	NULL
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	NULL
+VARIABLE_NAME	LEGACY_XA_ROLLBACK_AT_DISCONNECT
+VARIABLE_SCOPE	SESSION
+VARIABLE_TYPE	BOOLEAN
+VARIABLE_COMMENT	If a user session disconnects after putting a transaction into the XA PREPAREd state, roll back the transaction. Can be used for backwards compatibility to enable this pre-10.5 behavior for applications that expect it. Note that this violates the XA specification and should not be used for new code
+NUMERIC_MIN_VALUE	NULL
+NUMERIC_MAX_VALUE	NULL
+NUMERIC_BLOCK_SIZE	NULL
+ENUM_VALUE_LIST	OFF,ON
+READ_ONLY	NO
+COMMAND_LINE_ARGUMENT	OPTIONAL
 VARIABLE_NAME	LICENSE
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	VARCHAR

sql/sql_class.cc

@@ -1553,7 +1553,12 @@ void THD::cleanup(void)
   close_temporary_tables();
 
   if (transaction->xid_state.is_explicit_XA())
-    trans_xa_detach(this);
+  {
+    if (unlikely(variables.legacy_xa_rollback_at_disconnect))
+      xa_trans_force_rollback(this);
+    else
+      trans_xa_detach(this);
+  }
   else
     trans_rollback(this);
 

sql/sql_class.h

@@ -788,6 +788,7 @@ typedef struct system_variables
   my_bool binlog_annotate_row_events;
   my_bool binlog_direct_non_trans_update;
   my_bool column_compression_zlib_wrap;
+  my_bool legacy_xa_rollback_at_disconnect;
 
   plugin_ref table_plugin;
   plugin_ref tmp_table_plugin;

sql/sys_vars.cc

@@ -6788,3 +6788,13 @@ static Sys_var_ulonglong Sys_max_rowid_filter_size(
        SESSION_VAR(max_rowid_filter_size), CMD_LINE(REQUIRED_ARG),
        VALID_RANGE(1024, (ulonglong)~(intptr)0), DEFAULT(128*1024),
        BLOCK_SIZE(1));
+
+static Sys_var_mybool Sys_legacy_xa_rollback_at_disconnect(
+       "legacy_xa_rollback_at_disconnect",
+       "If a user session disconnects after putting a transaction into the XA "
+       "PREPAREd state, roll back the transaction. Can be used for backwards "
+       "compatibility to enable this pre-10.5 behavior for applications that "
+       "expect it. Note that this violates the XA specification and should not "
+       "be used for new code",
+       SESSION_VAR(legacy_xa_rollback_at_disconnect), CMD_LINE(OPT_ARG),
+       DEFAULT(FALSE), NO_MUTEX_GUARD, NOT_IN_BINLOG);

sql/xa.h

@@ -46,6 +46,7 @@ bool xid_cache_insert(XID *xid);
 bool xid_cache_insert(THD *thd, XID_STATE *xid_state, XID *xid);
 void xid_cache_delete(THD *thd, XID_STATE *xid_state);
 
+bool xa_trans_force_rollback(THD *thd);
 bool trans_xa_start(THD *thd);
 bool trans_xa_end(THD *thd);
 bool trans_xa_prepare(THD *thd);