+ add workaround for bug 38124
+ messages into the protocol when sessions are switched
+ replace error numbers by error names
+ reset of system variables to initial values per subtest
+ remove a file created by this test
+ minor improvements in structure and formatting
Adds --general_log_file, --slow_query_log_file command-
line options to match system variables of the same names.
Deprecates --log, --log-slow-queries command-line options
and log, log_slow_queries system-variables for v7.0; they
are superseded by general_log/general_log_file and
slow_query_log/slow_query_log_file, respectively.
general_log_file/slow_query_log_file.
The problem was that log file path was rejected if directory
path was empty. The fix is to reject log file path only if it
is entirely empty.
doesn't recognize it
This is a 5.1 version of the patch.
Problem:
'log' and 'log_slow_queries' were "fixed" variables, i.e. they showed up
in SHOW VARIABLES, but could not be used in expressions like
"select @@log". Also, using them in the SET statement produced an
incorrect "unknown system variable" error.
Solution:
Since as of MySQL 5.1.12 one can enable or disable the general query log
or the slow query log at runtime by changing values of
general_log/slow_query_log, make 'log' and 'log_slow_queries" to be
synonyms for 'general_log' and 'slow_query_log' respectively. This
makes expressions using the '@@var' syntax backward compatible with
5.0 and SHOW VARIABLES output to be consistent with the SET statement.
Problem: we don't evaluate given expression checking values of the
slow_query_log_file/general_log_file, don't check it for NULL.
Fix: evaluate the expression, check result returned.
Bug#25422 (Hang with log tables)
Bug 17876 (Truncating mysql.slow_log in a SP after using cursor locks the
thread)
Bug 23044 (Warnings on flush of a log table)
Bug 29129 (Resetting general_log while the GLOBAL READ LOCK is set causes
a deadlock)
Prior to this fix, the server would hang when performing concurrent
ALTER TABLE or TRUNCATE TABLE statements against the LOG TABLES,
which are mysql.general_log and mysql.slow_log.
The root cause traces to the following code:
in sql_base.cc, open_table()
if (table->in_use != thd)
{
/* wait_for_condition will unlock LOCK_open for us */
wait_for_condition(thd, &LOCK_open, &COND_refresh);
}
The problem with this code is that the current implementation of the
LOGGER creates 'fake' THD objects, like
- Log_to_csv_event_handler::general_log_thd
- Log_to_csv_event_handler::slow_log_thd
which are not associated to a real thread running in the server,
so that waiting for these non-existing threads to release table locks
cause the dead lock.
In general, the design of Log_to_csv_event_handler does not fit into the
general architecture of the server, so that the concept of general_log_thd
and slow_log_thd has to be abandoned:
- this implementation does not work with table locking
- it will not work with commands like SHOW PROCESSLIST
- having the log tables always opened does not integrate well with DDL
operations / FLUSH TABLES / SET GLOBAL READ_ONLY
With this patch, the fundamental design of the LOGGER has been changed to:
- always open and close a log table when writing a log
- remove totally the usage of fake THD objects
- clarify how locking of log tables is implemented in general.
See WL#3984 for details related to the new locking design.
Additional changes (misc bugs exposed and fixed):
1)
mysqldump which would ignore some tables in dump_all_tables_in_db(),
but forget to ignore the same in dump_all_views_in_db().
2)
mysqldump would also issue an empty "LOCK TABLE" command when all the tables
to lock are to be ignored (numrows == 0), instead of not issuing the query.
3)
Internal errors handlers could intercept errors but not warnings
(see sql_error.cc).
4)
Implementing a nested call to open tables, for the performance schema tables,
exposed an existing bug in remove_table_from_cache(), which would perform:
in_use->some_tables_deleted=1;
against another thread, without any consideration about thread locking.
This call inside remove_table_from_cache() was not required anyway,
since calling mysql_lock_abort() takes care of aborting -- cleanly -- threads
that might hold a lock on a table.
This line (in_use->some_tables_deleted=1) has been removed.
