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MDEV-10812 WSREP causes responses being sent to protocol commands

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that must not send a response

Problem:- When using wsrep (w/ galera) and issuing commands that can
cause deadlocks, deadlock exception errors are sent in responses to
commands such as close prepared statement and close connection which,
by spec, must not send a response.

Solution:- In dispatch_command, we will handle COM_QUIT and COM_STMT_CLOSE
commands even in case of error.

Patch Credit:- Jaka Močnik
This commit is contained in:
Sachin Setiya 2017-01-27 11:15:45 +05:30
parent bb1e8e4367
commit 41997d148d
3 changed files with 47 additions and 1 deletions
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11
mysql-test/suite/galera/r/galera_mdev_10812.result Normal file
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@ -0,0 +1,11 @@
#
# MDEV-10812: On COM_STMT_CLOSE/COM_QUIT, when wsrep_conflict_state
# is ABORTED, it causes wrong response to be sent to the client
#
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
CREATE TABLE t1(a INT PRIMARY KEY);
INSERT INTO t1 VALUES(1),(2),(3);
START TRANSACTION ;
UPDATE t1 SET a=a+100;
UPDATE t1 SET a=a+100;
DROP TABLE t1;

27
mysql-test/suite/galera/t/galera_mdev_10812.test Normal file
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@ -0,0 +1,27 @@
--source include/galera_cluster.inc
--source include/have_innodb.inc
--echo #
--echo # MDEV-10812: On COM_STMT_CLOSE/COM_QUIT, when wsrep_conflict_state
--echo # is ABORTED, it causes wrong response to be sent to the client
--echo #
# First create a deadlock
--connect node_1a, 127.0.0.1, root, , test, $NODE_MYPORT_1
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
CREATE TABLE t1(a INT PRIMARY KEY);
INSERT INTO t1 VALUES(1),(2),(3);
START TRANSACTION ;
UPDATE t1 SET a=a+100;
--sleep 2
--connection node_2
UPDATE t1 SET a=a+100;
--sleep 2
--connection node_1a
# here we get deadlock error
--disconnect node_1a
--connection node_2
DROP TABLE t1;

10
sql/sql_parse.cc
View File

@ -1265,7 +1265,9 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
{
wsrep_client_rollback(thd);
}
if (thd->wsrep_conflict_state== ABORTED)
/* We let COM_QUIT and COM_STMT_CLOSE to execute even if wsrep aborted. */
if (thd->wsrep_conflict_state == ABORTED &&
command != COM_STMT_CLOSE && command != COM_QUIT)
{
my_error(ER_LOCK_DEADLOCK, MYF(0), "wsrep aborted transaction");
WSREP_DEBUG("Deadlock error for: %s", thd->query());
@ -1918,6 +1920,12 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
if (WSREP(thd))
{
/*
MDEV-10812
In the case of COM_QUIT/COM_STMT_CLOSE thread status should be disabled.
*/
DBUG_ASSERT((command != COM_QUIT && command != COM_STMT_CLOSE)
|| thd->get_stmt_da()->is_disabled());
/* wsrep BF abort in query exec phase */
mysql_mutex_lock(&thd->LOCK_wsrep_thd);
do_end_of_statement= thd->wsrep_conflict_state != REPLAYING &&