Commit bbe92605 authored by Davi Arnaut's avatar Davi Arnaut

Bug#44664: valgrind warning for COMMIT_AND_CHAIN and ROLLBACK_AND_CHAIN

The problem is that the internal variable used to specify a
transaction with consistent read was being used outside the
processing context of a START TRANSACTION WITH CONSISTENT
SNAPSHOT statement. The practical consequence was that a
consistent snapshot specification could leak to unrelated
transactions on the same session.

The solution is to ensure a consistent snapshot clause is
only relied upon for the START TRANSACTION statement.

This is already fixed in a similar way on 6.0.
parent a4fba572
Branches unavailable
Tags unavailable
No related merge requests found
DROP TABLE IF EXISTS t1;
# Establish connection con1 (user=root)
# Establish connection con2 (user=root)
### Test 1:
### - While a consistent snapshot transaction is executed,
### no external inserts should be visible to the transaction.
# Switch to connection con1
CREATE TABLE t1 (a INT) ENGINE=innodb;
START TRANSACTION WITH CONSISTENT SNAPSHOT;
......@@ -10,6 +13,9 @@ INSERT INTO t1 VALUES(1);
SELECT * FROM t1;
a
COMMIT;
### Test 2:
### - For any non-consistent snapshot transaction, external
### committed inserts should be visible to the transaction.
DELETE FROM t1;
START TRANSACTION;
# Switch to connection con2
......@@ -19,5 +25,18 @@ SELECT * FROM t1;
a
1
COMMIT;
### Test 3:
### - Bug#44664: valgrind warning for COMMIT_AND_CHAIN and ROLLBACK_AND_CHAIN
### Chaining a transaction does not retain consistency level.
START TRANSACTION WITH CONSISTENT SNAPSHOT;
DELETE FROM t1;
COMMIT WORK AND CHAIN;
# Switch to connection con2
INSERT INTO t1 VALUES(1);
# Switch to connection con1
SELECT * FROM t1;
a
1
COMMIT;
# Switch to connection default + close connections con1 and con2
DROP TABLE t1;
......@@ -12,9 +12,9 @@ connect (con1,localhost,root,,);
--echo # Establish connection con2 (user=root)
connect (con2,localhost,root,,);
### Test 1:
### - While a consistent snapshot transaction is executed,
### no external inserts should be visible to the transaction.
--echo ### Test 1:
--echo ### - While a consistent snapshot transaction is executed,
--echo ### no external inserts should be visible to the transaction.
--echo # Switch to connection con1
connection con1;
......@@ -31,9 +31,9 @@ SELECT * FROM t1; # if consistent snapshot was set as expected, we
# should see nothing.
COMMIT;
### Test 2:
### - For any non-consistent snapshot transaction, external
### committed inserts should be visible to the transaction.
--echo ### Test 2:
--echo ### - For any non-consistent snapshot transaction, external
--echo ### committed inserts should be visible to the transaction.
DELETE FROM t1;
START TRANSACTION; # Now we omit WITH CONSISTENT SNAPSHOT
......@@ -48,6 +48,24 @@ SELECT * FROM t1; # if consistent snapshot was not set, as expected, we
# should see 1.
COMMIT;
--echo ### Test 3:
--echo ### - Bug#44664: valgrind warning for COMMIT_AND_CHAIN and ROLLBACK_AND_CHAIN
--echo ### Chaining a transaction does not retain consistency level.
START TRANSACTION WITH CONSISTENT SNAPSHOT;
DELETE FROM t1;
COMMIT WORK AND CHAIN;
--echo # Switch to connection con2
connection con2;
INSERT INTO t1 VALUES(1);
--echo # Switch to connection con1
connection con1;
SELECT * FROM t1; # if consistent snapshot was not set, as expected, we
# should see 1.
COMMIT;
--echo # Switch to connection default + close connections con1 and con2
connection default;
disconnect con1;
......
......@@ -198,8 +198,6 @@ bool begin_trans(THD *thd)
LEX *lex= thd->lex;
thd->options|= OPTION_BEGIN;
thd->server_status|= SERVER_STATUS_IN_TRANS;
if (lex->start_transaction_opt & MYSQL_START_TRANS_OPT_WITH_CONS_SNAPSHOT)
error= ha_start_consistent_snapshot(thd);
}
return error;
}
......@@ -4027,6 +4025,11 @@ mysql_execute_command(THD *thd)
}
if (begin_trans(thd))
goto error;
if (lex->start_transaction_opt & MYSQL_START_TRANS_OPT_WITH_CONS_SNAPSHOT)
{
if (ha_start_consistent_snapshot(thd))
goto error;
}
my_ok(thd);
break;
case SQLCOM_COMMIT:
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment