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.

mysql-test/r/consistent_snapshot.result:
  Add test case result for Bug#44664
mysql-test/t/consistent_snapshot.test:
  Add test case for Bug#44664
sql/sql_parse.cc:
  The WITH CONSISTENT SNAPSHOT clause is only valid for the
  START TRANSACTION statement.

1 files changed, 24 insertions, 6 deletions

diff --git a/mysql-test/t/consistent_snapshot.test b/mysql-test/t/consistent_snapshot.test
index 82edf2e22b2..fb1f3bc007c 100644
--- a/mysql-test/t/consistent_snapshot.test
+++ b/mysql-test/t/consistent_snapshot.test
@@ -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;