mariadb/mysql-test/suite/innodb/t/stats_persistent.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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--source include/have_innodb.inc
--source include/have_debug.inc
--source include/have_debug_sync.inc
--echo #
--echo # MDEV-23991 dict_table_stats_lock() has unnecessarily long scope
--echo #
CREATE TABLE t1(a INT) ENGINE=INNODB STATS_PERSISTENT=1;
SET DEBUG_SYNC='dict_stats_update_persistent SIGNAL stop WAIT_FOR go';
--send ANALYZE TABLE t1
--connect(con1, localhost, root)
SET DEBUG_SYNC='now WAIT_FOR stop';
--replace_column 1 SUM
SELECT SUM(DATA_LENGTH+INDEX_LENGTH) FROM information_schema.TABLES WHERE ENGINE='InnoDB';
SET DEBUG_SYNC='now SIGNAL go';
--disconnect con1
--connection default
--reap
SET DEBUG_SYNC= 'RESET';
DROP TABLE t1;