strict aliasing violations.
One somewhat major source of strict-aliasing violations and
related warnings is the SQL_LIST structure. For example,
consider its member function `link_in_list` which takes
a pointer to pointer of type T (any type) as a pointer to
pointer to unsigned char. Dereferencing this pointer, which
is done to reset the next field, violates strict-aliasing
rules and might cause problems for surrounding code that
uses the next field of the object being added to the list.
The solution is to use templates to parametrize the SQL_LIST
structure in order to deference the pointers with compatible
types. As a side bonus, it becomes possible to remove quite
a few casts related to acessing data members of SQL_LIST.
Analysis showed that in case of accessing I_S table
ROUTINES we perform unnecessary allocations
with get_field() function for every processed row that
in their turn causes significant memory growth.
the fix is to avoid use of get_field().
concurrent I_S query
There were two problem:
1) MYSQL_LOCK_IGNORE_FLUSH also ignored name locks
2) there was a race between abort_and_upgrade_locks and
alter_close_tables
(i.e. remove_table_from_cache and
close_data_files_and_morph_locks)
Which allowed the table to be opened with MYSQL_LOCK_IGNORE_FLUSH flag
resulting in renaming a partition that was already in use,
which could cause the table to be unusable.
Solution was to not allow IGNORE_FLUSH to skip waiting for
a named locked table.
And to not release the LOCK_open mutex between the
calls to remove_table_from_cache and
close_data_files_and_morph_locks by merging the functions
abort_and_upgrade_locks and alter_close_tables.
the fill_schema_processlist function accesses THD::query() without proper protection
so the parallel thread killing can lead to access to the freed meemory.
per-file comments:
sql/sql_load.cc
Bug#51377 Crash in information_schema / processlist on concurrent DDL workload
the THD::set_query_inner() call needs to be protected.
But here we don't need to change the original thd->query() at all.
sql/sql_show.cc
Bug#51377 Crash in information_schema / processlist on concurrent DDL workload
protect the THD::query() access with the THD::LOCK_thd_data mutex.
check_access() returning false for a database does not
guarantee that the access is granted to it.
This wrong condition in filling the INFORMATION_SCHEMA
tables causes extra tables to be returned to the user
even if he has no rights to see them.
Fixed by correcting the condition.
When checking for an error after removing the special view error handler the code
was not taking into account that open_tables() may fail because of the current
statement being killed.
Added a check for thd->killed.
Added a client program to test it.
Implemented the server infrastructure for the fix:
1. Added a function LEX_STRING *thd_query_string(THD) to return
a LEX_STRING structure instead of char *.
This is the function that must be called in innodb instead of
thd_query()
2. Did some encapsulation in THD : aggregated thd_query and
thd_query_length into a LEX_STRING and made accessor and mutator
methods for easy code updating.
3. Updated the server code to use the new methods where applicable.
view definition
During SHOW CREATE VIEW there is no reason to 'anonymize'
errors that name objects that a user does not have access
to. Moreover it was inconsistently implemented. For example
base tables being referenced from a view appear to be ok,
but not views. The manual on the other hand is clear: If a
user has the privileges SELECT and SHOW VIEW, the view
definition is available to that user, period. The fix
changes the behavior to support the manual.
on SHOW CREATE TRIGGER + MERGE table
Problem: SHOW CREATE TRIGGER erroneously relies on fact
that we have the only underlying table for a trigger
(wrong for merge tables).
Fix: remove erroneous assert().
those keywords do nothing in 5.1 (they are meant for future versions, for example featuring the Maria engine)
so they are here removed from the syntax. Adding those keywords to future versions when needed is:
- WL#5034 "Add TRANSACTIONA=0|1 and PAGE_CHECKSUM=0|1 clauses to CREATE TABLE"
- WL#5037 "New ROW_FORMAT value for CREATE TABLE: PAGE"
procedures causes crashes!
The problem of that bugreport was mostly fixed by the
patch for bug 38691.
However, attached test case focused on another crash or
valgrind warning problem: SHOW PROCESSLIST query accesses
freed memory of SP instruction that run in a parallel
connection.
Changes of thd->query/thd->query_length in dangerous
places have been guarded with the per-thread
LOCK_thd_data mutex (the THD::LOCK_delete mutex has been
renamed to THD::LOCK_thd_data).
"create as select" (innodb table)
Problem: code constructing "CREATE TABLE..." statement
doesn't take into account that current database is not set
in some cases. That may lead to a server crash.
Fix: check if current database is set.
The problem: described in the bug report.
The fix:
--increase buffers where it's necessary
(buffers which are used in stxnmov)
--decrease buffer lengths which are used
with gcc 4.3.2
Compiling MySQL with gcc 4.3.2 and later produces a number of
warnings, many of which are new with the recent compiler
versions.
This bug will be resolved in more than one patch to limit the
size of changesets. This is the second patch, fixing more
of the warnings.
with gcc 4.3.2
Compiling MySQL with gcc 4.3.2 and later produces a number of
warnings, many of which are new with the recent compiler
versions.
This bug will be resolved in more than one patch to limit the
size of changesets. This is the second patch, fixing more
of the warnings.
the thread->mysys_var parameter should be empty for the idle
embedded-server threads so that working threads can safely free
this memory.
per-file comments:
libmysqld/lib_sql.cc
Bug#43733 Select on processlist let the embedded server crash (concurrent_innodb_safelog)
set thread->mysys_var= 0 after the query is handled
mysql-test/include/concurrent.inc
Bug#43733 Select on processlist let the embedded server crash (concurrent_innodb_safelog)
enable these for the embedded-server mode
sql/sql_show.cc
Bug#43733 Select on processlist let the embedded server crash (concurrent_innodb_safelog)
show thread lock status in the query result
become negative
- merged the fix to 5.1
- extended to cover I_S.PROCESSLIST.TIME
- Changed the column type of I_S.PROCESSLIST.TIME from LOGNLONG
UNSIGNED
to LONG (to match the SHOW PROCESSLIST type)
- Added a test case
seems to become negative
THD::start_time has a dual meaning : it's either the time since the process
entered a given state or is the transaction time returned by e.g. NOW().
This causes problems, as sometimes THD::start_time may be set to a value
that is correct and needed when used as a base for NOW(), but these times
may be arbitrary (SET @@timestamp) or non-local (coming from the master
through the replication feed).
If one such non-local time is set there's no way to return a correct value
for e.g. SHOW PROCESSLIST or SELECT ... FROM INFORMATION_SCHEMA.PROCESSLIST.
Fixed by making the Time column in SHOW PROCESSLIST SIGNED LONG instead of
UNSIGNED LONG and doing the correct conversions.
Note that no reliable test suite can be constructed, since it would require
knowing the local time and can't be achieved by the means of the current test
suite.
- Remove bothersome warning messages. This change focuses on the warnings
that are covered by the ignore file: support-files/compiler_warnings.supp.
- Strings are guaranteed to be max uint in length
Added global status variable 'Queries' which represents
total amount of queries executed by server including
statements executed by SPs.
note: It's old behaviour of 'Questions' variable.
The problem is that we cannot insert new record into memory table
when table size exceeds max memory table size.
The fix is to use schema_table_store_record() function which
converts memory table into MyISAM in case of table size exceeding.
Note:
There is no test case for this bug, the reason is that
1. The code that was added already is checked(i.e. works) with existing tests
2. Correct work of schema_table_store_record() is checked with other test cases
(information_schema tests)
So new code is fully covered with existing test cases.
Static disabled plugins|engines and dynamic plugins which installed but disabled
are not visible in I_S PLUGINS|ENGINES tables because they are not stored into
global plugin array.
The fix: add such plugins|engines to plugin array with PLUGIN_IS_DISABLED status.
I_S.ENGINES 'Transactions', 'XA', 'Savepoints' fields have NULL value in this case.
