mariadb/mysql-test/main/client_xml.test
Sergei Golubchik bead24b7f3 mariadb-test: wait on disconnect
Remove one of the major sources of race condiitons in mariadb-test.
Normally, mariadb_close() sends COM_QUIT to the server and immediately
disconnects. In mariadb-test it means the test can switch to another
connection and sends queries to the server before the server even
started parsing the COM_QUIT packet and these queries can see the
connection as fully active, as it didn't reach dispatch_command yet.

This is a major source of instability in tests and many - but not all,
still less than a half - tests employ workarounds. The correct one
is a pair count_sessions.inc/wait_until_count_sessions.inc.
Also very popular was wait_until_disconnected.inc, which was completely
useless, because it verifies that the connection is closed, and after
disconnect it always is, it didn't verify whether the server processed
COM_QUIT. Sadly the placebo was as widely used as the real thing.

Let's fix this by making mariadb-test `disconnect` command _to wait_ for
the server to confirm. This makes almost all workarounds redundant.

In some cases count_sessions.inc/wait_until_count_sessions.inc is still
needed, though, as only `disconnect` command is changed:

 * after external tools, like `exec $MYSQL`
 * after failed `connect` command
 * replication, after `STOP SLAVE`
 * Federated/CONNECT/SPIDER/etc after `DROP TABLE`

and also in some XA tests, because an XA transaction is dissociated from
the THD very late, after the server has closed the client connection.

Collateral cleanups: fix comments, remove some redundant statements:
 * DROP IF EXISTS if nothing is known to exist
 * DROP table/view before DROP DATABASE
 * REVOKE privileges before DROP USER
 etc
2025-07-16 09:14:33 +07:00

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# Can't run with embedded server
--source include/not_embedded.inc
--source include/no_view_protocol.inc
# Disable concurrent inserts to avoid test failures when reading
# data from concurrent connections (insert might return before
# the data is actually in the table).
set @old_concurrent_insert= @@global.concurrent_insert;
set @@global.concurrent_insert= 0;
# Test of the xml output of the 'mysql' and 'mysqldump' clients -- makes
# sure that basic encoding issues are handled properly
create table t1 (
`a&b` int,
`a<b` int NOT NULL,
`a>b` text
);
insert into t1 values (1, 2, 'a&b a<b a>b');
# Determine the number of open sessions
--source include/count_sessions.inc
--exec $MYSQL --xml test -e "select * from t1"
--exec $MYSQL_DUMP --xml --skip-create-options test
--exec $MYSQL --xml test -e "select count(*) from t1"
--exec $MYSQL --xml test -e "select 1 < 2 from dual"
--exec $MYSQL --xml test -e "select 1 > 2 from dual"
--exec $MYSQL --xml test -e "select 1 & 3 from dual"
--exec $MYSQL --xml test -e "select null from dual"
--exec $MYSQL --xml test -e "select 1 limit 0"
--exec $MYSQL --xml test -vv -e "select 1 limit 0"
drop table t1;
# Restore global concurrent_insert value
set @@global.concurrent_insert= @old_concurrent_insert;
# Wait till the number of open sessions is <= the number before the runs with
# $MYSQL and $MYSQL_DUMP
# = The session caused by mysql and mysqldump have finished their disconnect
--source include/wait_until_count_sessions.inc