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Bug #54105 assert in MDL_context::release_locks_stored_before

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The problem was that SHOW CREATE EVENT released all metadata locks
held by the current transaction. This made any exisiting savepoints
invalid, triggering the assert when ROLLBACK TO SAVEPOINT later
was executed.

This patch fixes the problem by making sure SHOW CREATE EVENT only
releases metadata locks acquired by the statement itself.

Test case added to event_trans.test.
This commit is contained in:
Jon Olav Hauglid
2010-08-13 10:02:37 +02:00
parent 7349ddae6f
commit 3bc4d54073
4 changed files with 58 additions and 8 deletions
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19
mysql-test/r/events_trans.result
View File

@@ -116,3 +116,22 @@ OK: create event: database does not exist
delete from t1;
commit work;
drop database events_test;
#
# Bug#54105 assert in MDL_context::release_locks_stored_before
#
USE test;
DROP TABLE IF EXISTS t1, t2;
DROP EVENT IF EXISTS e1;
CREATE TABLE t1 (a INT) ENGINE=InnoDB;
CREATE TABLE t2 (a INT);
CREATE EVENT e1 ON SCHEDULE EVERY 1 DAY DO SELECT 1;
START TRANSACTION;
INSERT INTO t1 VALUES (1);
SAVEPOINT A;
SHOW CREATE EVENT e1;
Event sql_mode time_zone Create Event character_set_client collation_connection Database Collation
e1 SYSTEM CREATE DEFINER=`root`@`localhost` EVENT `e1` ON SCHEDULE EVERY 1 DAY STARTS '#' ON COMPLETION NOT PRESERVE ENABLE DO SELECT 1 latin1 latin1_swedish_ci latin1_swedish_ci
SELECT * FROM t2;
a
ROLLBACK WORK TO SAVEPOINT A;
DROP TABLE t1, t2;

25
mysql-test/t/events_trans.test
View File

@@ -121,3 +121,28 @@ let $wait_condition=
drop database events_test;
--echo #
--echo # Bug#54105 assert in MDL_context::release_locks_stored_before
--echo #
USE test;
--disable_warnings
DROP TABLE IF EXISTS t1, t2;
DROP EVENT IF EXISTS e1;
--enable_warnings
CREATE TABLE t1 (a INT) ENGINE=InnoDB;
CREATE TABLE t2 (a INT);
CREATE EVENT e1 ON SCHEDULE EVERY 1 DAY DO SELECT 1;
START TRANSACTION;
INSERT INTO t1 VALUES (1);
SAVEPOINT A;
--replace_regex /STARTS '[^']+'/STARTS '#'/
SHOW CREATE EVENT e1;
SELECT * FROM t2;
ROLLBACK WORK TO SAVEPOINT A;
DROP TABLE t1, t2;

19
sql/event_db_repository.cc
View File

@@ -996,24 +996,33 @@ Event_db_repository::load_named_event(THD *thd, LEX_STRING dbname,
LEX_STRING name, Event_basic *etn)
{
bool ret;
TABLE *table= NULL;
ulong saved_mode= thd->variables.sql_mode;
Open_tables_backup open_tables_backup;
TABLE_LIST event_table;
DBUG_ENTER("Event_db_repository::load_named_event");
DBUG_PRINT("enter",("thd: 0x%lx name: %*s", (long) thd,
(int) name.length, name.str));
event_table.init_one_table("mysql", 5, "event", 5, "event", TL_READ);
/* Reset sql_mode during data dictionary operations. */
thd->variables.sql_mode= 0;
if (!(ret= open_event_table(thd, TL_READ, &table)))
/*
We don't use open_event_table() here to make sure that SHOW
CREATE EVENT works properly in transactional context, and
does not release transactional metadata locks when the
event table is closed.
*/
if (!(ret= open_system_tables_for_read(thd, &event_table, &open_tables_backup)))
{
if ((ret= find_named_event(dbname, name, table)))
if ((ret= find_named_event(dbname, name, event_table.table)))
my_error(ER_EVENT_DOES_NOT_EXIST, MYF(0), name.str);
else if ((ret= etn->load_from_row(thd, table)))
else if ((ret= etn->load_from_row(thd, event_table.table)))
my_error(ER_CANNOT_LOAD_FROM_TABLE, MYF(0), "event");
close_mysql_tables(thd);
close_system_tables(thd, &open_tables_backup);
}
thd->variables.sql_mode= saved_mode;

3
sql/events.cc
View File

@@ -699,7 +699,6 @@ send_show_create_event(THD *thd, Event_timed *et, Protocol *protocol)
bool
Events::show_create_event(THD *thd, LEX_STRING dbname, LEX_STRING name)
{
Open_tables_backup open_tables_backup;
Event_timed et;
bool ret;
@@ -722,9 +721,7 @@ Events::show_create_event(THD *thd, LEX_STRING dbname, LEX_STRING name)
deadlock can occur please refer to the description of 'system table'
flag.
*/
thd->reset_n_backup_open_tables_state(&open_tables_backup);
ret= db_repository->load_named_event(thd, dbname, name, &et);
thd->restore_backup_open_tables_state(&open_tables_backup);
if (!ret)
ret= send_show_create_event(thd, &et, thd->protocol);