in mysqld--help test.
When mysql is compiled with different options,columns
might have different size (this depends on parameter
names and some parameters might only be available
when some option is switched on)
This change is supposed to reduce number of ER_LOCK_DEADLOCK
errors which occur when multi-statement transaction encounters
conflicting metadata lock in cases when waiting is possible.
The idea is not to fail ER_LOCK_DEADLOCK error immediately when
we encounter conflicting metadata lock. Instead we release all
metadata locks acquired by current statement and start to wait
until conflicting lock go away. To avoid deadlocks we use simple
empiric which aborts waiting with ER_LOCK_DEADLOCK error if it
turns out that somebody is waiting for metadata locks owned by
this transaction.
This patch also fixes bug #46273 "MySQL 5.4.4 new MDL: Bug#989
is not fully fixed in case of ALTER".
The bug was that concurrent execution of UPDATE or MULTI-UPDATE
statement as a part of multi-statement transaction that already
has used table being updated and ALTER TABLE statement might have
resulted of loss of isolation between this transaction and ALTER
TABLE statement, which manifested itself as changes performed by
ALTER TABLE becoming visible in transaction and wrong binary log
order as a consequence.
This problem occurred when UPDATE or MULTI-UPDATE's wait in
mysql_lock_tables() call was aborted due to metadata lock
upgrade performed by concurrent ALTER TABLE. After such abort all
metadata locks held by transaction were released but transaction
silently continued to be executed as if nothing has happened.
We solve this problem by changing our code not to release all
locks in such case. Instead we release only locks which were
acquired by current statement and then try to reacquire them
by restarting open/lock tables process. We piggyback on simple
deadlock detector implementation since this change has to be
done anyway for it.
mysql-test/include/handler.inc:
After introduction of basic deadlock detector for metadata locks
it became necessary to change parts of test for HANDLER statements
which covered some of scenarios in which ER_LOCK_DEADLOCK error
was detected in absence of real deadlock (with new deadlock detector
this no longer happens).
Also adjusted test to the fact that HANDLER READ for the table no
longer will be blocked by ALTER TABLE for the same table which awaits
for metadata lock upgrade (this is due to removal of mysql_lock_abort()
from wait_while_table_is_used()).
mysql-test/r/handler_innodb.result:
After introduction of basic deadlock detector for metadata locks
it became necessary to change parts of test for HANDLER statements
which covered some of scenarios in which ER_LOCK_DEADLOCK error
was detected in absence of real deadlock (with new deadlock detector
this no longer happens).
Also adjusted test to the fact that HANDLER READ for the table no
longer will be blocked by ALTER TABLE for the same table which awaits
for metadata lock upgrade (this is due to removal of mysql_lock_abort()
from wait_while_table_is_used()).
mysql-test/r/handler_myisam.result:
After introduction of basic deadlock detector for metadata locks
it became necessary to change parts of test for HANDLER statements
which covered some of scenarios in which ER_LOCK_DEADLOCK error
was detected in absence of real deadlock (with new deadlock detector
this no longer happens).
Also adjusted test to the fact that HANDLER READ for the table no
longer will be blocked by ALTER TABLE for the same table which awaits
for metadata lock upgrade (this is due to removal of mysql_lock_abort()
from wait_while_table_is_used()).
mysql-test/r/mdl_sync.result:
Added test coverage for basic deadlock detection in metadata
locking subsystem and for bug #46273 "MySQL 5.4.4 new MDL:
Bug#989 is not fully fixed in case of ALTER".
mysql-test/r/sp-lock.result:
Adjusted test coverage for metadata locking for stored routines
since after introduction of basic deadlock detector for metadata
locks number of scenarios in which ER_LOCK_DEADLOCK error in
absence of deadlock has decreased.
mysql-test/t/mdl_sync.test:
Added test coverage for basic deadlock detection in metadata
locking subsystem and for bug #46273 "MySQL 5.4.4 new MDL:
Bug#989 is not fully fixed in case of ALTER".
mysql-test/t/sp-lock.test:
Adjusted test coverage for metadata locking for stored routines
since after introduction of basic deadlock detector for metadata
locks number of scenarios in which ER_LOCK_DEADLOCK error in
absence of deadlock has decreased.
sql/log_event_old.cc:
close_tables_for_reopen() now takes one more argument which
specifies at which point it should stop releasing metadata
locks acquired by this connection.
sql/mdl.cc:
Changed metadata locking subsystem to support basic deadlock detection
with a help of the following simple empiric -- we assume that there is
a deadlock if there is a connection which has to wait for a metadata
lock which is currently acquired by some connection which is itself
waiting to be able to acquire some shared metadata lock.
To implement this change:
- Added MDL_context::can_wait_lead_to_deadlock()/_impl() methods
which allow to find out if there is someone waiting for metadata
lock which is held by the connection and therefore deadlocks are
possible if this connection is going to wait for some metadata lock.
To do this added version of MDL_ticket::has_pending_conflicting_lock()
method which assumes that its caller already owns LOCK_mdl mutex.
- Changed MDL_context::wait_for_locks() to use one of the above methods
to check if somebody is waiting for metadata lock owned by this
context (and therefore deadlock is possible) and emit ER_LOCK_DEADLOCK
error in this case. Also now we mark context of connections waiting
inside of this method by setting MDL_context::m_is_waiting_in_mdl
member. Thanks to this such connection could be waken up if some
other connection starts waiting for one of its metadata locks and
so a deadlock can occur.
- Adjusted notify_shared_lock() to wake up connections which wait inside
MDL_context::wait_for_locks() while holding shared metadata lock.
- Changed MDL_ticket::upgrade_shared_lock_to_exclusive() to add
temporary ticket for exclusive lock to MDL_lock::waiting queue, so
request for metadata lock upgrade can be properly detected by our
empiric.
Also now this method invokes a callback which forces transactions
holding shared metadata lock on the table to call MDL_context::
can_wait_lead_to_deadlock() method even if they don't need any new
metadata locks. Thanks to this such transactions can detect deadlocks/
livelocks between MDL and table-level locks.
Also reduced timeouts between calls to notify_shared_lock()
in MDL_ticket::upgrade_shared_lock_to_exclusive() and
MDL_context::acquire_exclusive_locks(). This was necessary
to get rid of call to mysql_lock_abort() in wait_while_table_is_used().
(Now we instead rely on notify_shared_lock() timely calling
mysql_lock_abort_for_thread() for the table on which lock
is being upgraded/acquired).
sql/mdl.h:
- Added a version of MDL_ticket::has_pending_conflicting_lock() method
to be used in situations when caller already has acquired LOCK_mdl
mutex.
- Added MDL_context::can_wait_lead_to_deadlock()/_impl() methods
which allow to find out if there is someone waiting for metadata lock
which is held by this connection and thus deadlocks are possible if
this connections will start waiting for some metadata lock.
- Added MDL_context::m_is_waiting_in_mdl member to mark connections
waiting in MDL_context::wait_for_locks() method of metadata locking
subsystem. Added getter method for this private member to make it
accessible in notify_shared_lock() auxiliary so we can wake-up such
connections if they hold shared metadata locks.
- Finally, added mysql_abort_transactions_with_shared_lock() callback
to be able force transactions which don't need any new metadata
locks still call MDL_context::can_wait_lead_to_deadlock() and detect
some of deadlocks between metadata locks and table-level locks.
sql/mysql_priv.h:
close_tables_for_reopen() now takes one more argument which
specifies at which point it should stop releasing metadata
locks acquired by this connection.
sql/sql_base.cc:
Changed approach to metadata locking for multi-statement transactions.
We no longer fail ER_LOCK_DEADLOCK error immediately when we encounter
conflicting metadata lock. Instead we release all metadata locks
acquired by current statement and start to wait until conflicting
locks to go away by calling MDL_context::wait_for_locks() method.
To avoid deadlocks the latter implements simple empiric which aborts
waiting with ER_LOCK_DEADLOCK error if it turns out that somebody
is waiting for metadata locks owned by this transaction.
To implement the change described above:
- Introduced Open_table_context::m_start_of_statement_svp member to
store state of metadata locks at the start of the statement.
- Changed Open_table_context::request_backoff_action() not to
fail with ER_LOCK_DEADLOCK immediately if back-off is requested
due to conflicting metadata lock.
- Added new argument for close_tables_for_reopen() procedure which
allows to specify subset of metadata locks to be released.
- Changed open_tables() not to release all metadata locks acquired
by current transaction when metadata lock conflict is discovered.
Instead we release only locks acquired by current statement.
- Changed open_ltable() and open_and_lock_tables_derived() not to emit
ER_LOCK_DEADLOCK error when mysql_lock_tables() is aborted in
multi-statement transaction when somebody tries to acquire exclusive
metadata lock on the table. Instead we release metadata locks acquired
by current statement and try to wait until they can be re-acquired.
- Adjusted tdc_wait_for_old_versions() to check if there is someone
waiting for one of metadata locks held by this connection and run
deadlock detection in order to avoid deadlocks in some
situations.
- Added mysql_abort_transactions_with_shared_lock() callback which
allows to force transactions holding shared metadata lock on the
table to call MDL_context::can_wait_lead_to_deadlock() even if they
don't need any new metadata locks so they can detect potential
deadlocks between metadata locking subsystem and table-level locks.
- Adjusted wait_while_table_is_used() not to set TABLE::version to
0 as it is now done only when necessary by the above-mentioned
callback. Also removed unnecessary call to mysql_lock_abort().
Instead we rely on code performing metadata lock upgrade aborting
waits on the table-level lock for this table by calling
mysql_lock_abort_for_thread() (invoked by
mysql_notify_thread_having_shared_lock()). In future this should
allow to reduce number of scenarios in which we produce
ER_LOCK_DEADLOCK error even though no real deadlock exists.
sql/sql_class.h:
Introduced Open_table_context::m_start_of_statement_svp member to
store state of metadata locks at the start of the statement.
Replaced Open_table_context::m_can_deadlock member with m_has_locks
member to reflect the fact that we no longer unconditionally emit
ER_LOCK_DEADLOCK error for transaction having some metadata locks
when conflicting metadata lock is discovered.
sql/sql_insert.cc:
close_tables_for_reopen() now takes one more argument which
specifies at which point it should stop releasing metadata
locks acquired by this connection.
sql/sql_plist.h:
Made I_P_List_iterator<T, B> usable with const lists.
sql/sql_show.cc:
close_tables_for_reopen() now takes one more argument which
specifies at which point it should stop releasing metadata
locks acquired by this connection.
sql/sql_update.cc:
Changed UPDATE and MULTI-UPDATE code not to release all metadata
locks when calls to mysql_lock_tables() are aborted. Instead we
release only locks which are acquired by this statement and then
try to reacquire them by calling open_tables(). This solves
bug #46273 "MySQL 5.4.4 new MDL: Bug#989 is not fully fixed in
case of ALTER".
"HANDLER statements within a transaction might lead to deadlocks".
Introduce a notion of a sentinel to MDL_context. A sentinel
is a ticket that separates all tickets in the context into two
groups: before and after it. Currently we can have (and need) only
one designated sentinel -- it separates all locks taken by LOCK
TABLE or HANDLER statement, which must survive COMMIT and ROLLBACK
and all other locks, which must be released at COMMIT or ROLLBACK.
The tricky part is maintaining the sentinel up to date when
someone release its corresponding ticket. This can happen, e.g.
if someone issues DROP TABLE under LOCK TABLES (generally,
see all calls to release_all_locks_for_name()).
MDL_context::release_ticket() is modified to take care of it.
******
A fix and a test case for Bug#46224 "HANDLER statements within a
transaction might lead to deadlocks".
An attempt to mix HANDLER SQL statements, which are transaction-
agnostic, an open multi-statement transaction,
and DDL against the involved tables (in a concurrent connection)
could lead to a deadlock. The deadlock would occur when
HANDLER OPEN or HANDLER READ would have to wait on a conflicting
metadata lock. If the connection that issued HANDLER statement
also had other metadata locks (say, acquired in scope of a
transaction), a classical deadlock situation of mutual wait
could occur.
Incompatible change: entering LOCK TABLES mode automatically
closes all open HANDLERs in the current connection.
Incompatible change: previously an attempt to wait on a lock
in a connection that has an open HANDLER statement could wait
indefinitely/deadlock. After this patch, an error ER_LOCK_DEADLOCK
is produced.
The idea of the fix is to merge thd->handler_mdl_context
with the main mdl_context of the connection, used for transactional
locks. This makes deadlock detection possible, since all waits
with locks are "visible" and available to analysis in a single
MDL context of the connection.
Since HANDLER locks and transactional locks have a different life
cycle -- HANDLERs are explicitly open and closed, and so
are HANDLER locks, explicitly acquired and released, whereas
transactional locks "accumulate" till the end of a transaction
and are released only with COMMIT, ROLLBACK and ROLLBACK TO SAVEPOINT,
a concept of "sentinel" was introduced to MDL_context.
All locks, HANDLER and others, reside in the same linked list.
However, a selected element of the list separates locks with
different life cycle. HANDLER locks always reside at the
end of the list, after the sentinel. Transactional locks are
prepended to the beginning of the list, before the sentinel.
Thus, ROLLBACK, COMMIT or ROLLBACK TO SAVEPOINT, only
release those locks that reside before the sentinel. HANDLER locks
must be released explicitly as part of HANDLER CLOSE statement,
or an implicit close.
The same approach with sentinel
is also employed for LOCK TABLES locks. Since HANDLER and LOCK TABLES
statement has never worked together, the implementation is
made simple and only maintains one sentinel, which is used either
for HANDLER locks, or for LOCK TABLES locks.
mysql-test/include/handler.inc:
Add test coverage for Bug#46224 "HANDLER statements within a
transaction might lead to deadlocks".
Extended HANDLER coverage to cover a mix of HANDLER, transactions
and DDL statements.
mysql-test/r/handler_innodb.result:
Update results (Bug#46224).
mysql-test/r/handler_myisam.result:
Update results (Bug#46224).
sql/lock.cc:
Remove thd->some_tables_deleted, it's never used.
sql/log_event.cc:
No need to check for thd->locked_tables_mode,
it's done inside release_transactional_locks().
sql/mdl.cc:
Implement the concept of HANDLER and LOCK TABLES "sentinel".
Implement a method to clone an acquired ticket.
Do not return tickets beyond the sentinel when acquiring
locks, create a copy.
Remove methods to merge and backup MDL_context, they are now
not used (Hurra!). This opens a path to a proper constructor
and destructor of class MDL_context (to be done in a separate
patch).
Modify find_ticket() to provide information about where
the ticket position is with regard to the sentinel.
sql/mdl.h:
Add declarations necessary for the implementation of the concept
of "sentinel", a dedicated ticket separating transactional and
non-transactional locks.
sql/mysql_priv.h:
Add mark_tmp_table_for_reuse() declaration,
a function to "close" a single session (temporary) table.
sql/sql_base.cc:
Remove thd->some_tables_deleted.
Modify deadlock-prevention asserts and deadlock detection
heuristics to take into account that from now on HANDLER locks
reside in the same locking context.
Add broadcast_refresh() to mysql_notify_thread_having_shared_lock():
this is necessary for the case when a thread having a shared lock
is asleep in tdc_wait_for_old_versions(). This situation is only
possible with HANDLER t1 OPEN; FLUSH TABLE (since all over code paths
that lead to tdc_wait_for_old_versions() always have an
empty MDL_context). Previously the server would simply deadlock
in this situation.
sql/sql_class.cc:
Remove now unused member "THD::some_tables_deleted".
Move mysql_ha_cleanup() a few lines above in THD::cleanup()
to make sure that all handlers are closed when it's time to
destroy the MDL_context of this connection.
Remove handler_mdl_context and handler_tables.
sql/sql_class.h:
Remove THD::handler_tables, THD::handler_mdl_context,
THD::some_tables_deleted.
sql/sql_handler.cc:
Remove thd->handler_tables.
Remove thd->handler_mdl_context.
Rewrite mysql_ha_open() to have no special provision for MERGE
tables, now that we don't have to manipulate with thd->handler_tables
it's easy to do.
Remove dead code.
Fix a bug in mysql_ha_flush() when we would always flush
a temporary HANDLER when mysql_ha_flush() is called (actually
mysql_ha_flush() never needs to flush temporary tables).
sql/sql_insert.cc:
Update a comment, no more thd->some_tables_deleted.
sql/sql_parse.cc:
Implement an incompatible change: entering LOCK TABLES closes
active HANDLERs, if any.
Now that we have a sentinel, we don't need to check
for thd->locked_tables_mode when releasing metadata locks in
COMMIT/ROLLBACK.
sql/sql_plist.h:
Add new (now necessary) methods to the list class.
sql/sql_prepare.cc:
Make sure we don't release HANDLER locks when rollback to a
savepoint, set to not keep locks taken at PREPARE.
sql/sql_servers.cc:
Update to a new signature of MDL_context::release_all_locks().
sql/sql_table.cc:
Remove thd->some_tables_deleted.
sql/transaction.cc:
Add comments.
Make sure rollback to (MDL) savepoint works under LOCK TABLES and
with HANDLER tables.
Bug#16565 mysqld --help --verbose does not order variablesBug#20413 sql_slave_skip_counter is not shown in show variables
Bug#20415 Output of mysqld --help --verbose is incomplete
Bug#25430 variable not found in SELECT @@global.ft_max_word_len;
Bug#32902 plugin variables don't know their names
Bug#34599 MySQLD Option and Variable Reference need to be consistent in formatting!
Bug#34829 No default value for variable and setting default does not raise error
Bug#34834 ? Is accepted as a valid sql mode
Bug#34878 Few variables have default value according to documentation but error occurs
Bug#34883 ft_boolean_syntax cant be assigned from user variable to global var.
Bug#37187 `INFORMATION_SCHEMA`.`GLOBAL_VARIABLES`: inconsistent status
Bug#40988 log_output_basic.test succeeded though syntactically false.
Bug#41010 enum-style command-line options are not honoured (maria.maria-recover fails)
Bug#42103 Setting key_buffer_size to a negative value may lead to very large allocations
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
Bug#44797 plugins w/o command-line options have no disabling option in --help
Bug#46314 string system variables don't support expressions
Bug#46470 sys_vars.max_binlog_cache_size_basic_32 is broken
Bug#46586 When using the plugin interface the type "set" for options caused a crash.
Bug#47212 Crash in DBUG_PRINT in mysqltest.cc when trying to print octal number
Bug#48758 mysqltest crashes on sys_vars.collation_server_basic in gcov builds
Bug#49417 some complaints about mysqld --help --verbose output
Bug#49540 DEFAULT value of binlog_format isn't the default value
Bug#49640 ambiguous option '--skip-skip-myisam' (double skip prefix)
Bug#49644 init_connect and \0
Bug#49645 init_slave and multi-byte characters
Bug#49646 mysql --show-warnings crashes when server dies
CMakeLists.txt:
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
client/mysql.cc:
don't crash with --show-warnings when mysqld dies
config/ac-macros/plugins.m4:
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
include/my_getopt.h:
comments
include/my_pthread.h:
fix double #define
mysql-test/mysql-test-run.pl:
run sys_vars suite by default
properly recognize envirinment variables (e.g. MTR_MAX_SAVE_CORE) set to 0
escape gdb command line arguments
mysql-test/suite/sys_vars/r/rpl_init_slave_func.result:
init_slave+utf8 bug
mysql-test/suite/sys_vars/t/rpl_init_slave_func.test:
init_slave+utf8 bug
mysys/my_getopt.c:
Bug#34599 MySQLD Option and Variable Reference need to be consistent in formatting!
Bug#46586 When using the plugin interface the type "set" for options caused a crash.
Bug#49640 ambiguous option '--skip-skip-myisam' (double skip prefix)
mysys/typelib.c:
support for flagset
sql/ha_ndbcluster.cc:
backport from telco tree
sql/item_func.cc:
Bug#49644 init_connect and \0
Bug#49645 init_slave and multi-byte characters
sql/sql_builtin.cc.in:
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
sql/sql_plugin.cc:
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
Bug#32902 plugin variables don't know their names
Bug#44797 plugins w/o command-line options have no disabling option in --help
sql/sys_vars.cc:
all server variables are defined here
storage/myisam/ft_parser.c:
remove unnecessary updates of param->quot
storage/myisam/ha_myisam.cc:
myisam_* variables belong here
strings/my_vsnprintf.c:
%o and %llx
unittest/mysys/my_vsnprintf-t.c:
%o and %llx tests
vio/viosocket.c:
bugfix: fix @@wait_timeout to work with socket timeouts (vs. alarm thread)
mysql-test/include/kill_query.inc:
Error 1034 can be generated when change MyISAM table indexes was interrupted
mysql-test/r/rpl_killed_ddl.result:
table t4 may not exists because the ALTER above was interrupted
mysql-test/t/rpl_killed_ddl.test:
table t4 may not exists because the ALTER above was interrupted
Bug #42147 Concurrent DML and LOCK TABLE ... READ for InnoDB
table cause warnings in errlog
Concurrent execution of LOCK TABLES ... READ statement and DML statements
affecting the same InnoDB table on debug builds of MySQL server might lead
to "Found lock of type 6 that is write and read locked" warnings appearing
in error log.
The problem is that the table-level locking code allows a thread to acquire
TL_READ_NO_INSERT lock on a table even if there is another thread which holds
TL_WRITE_ALLOW_WRITE lock on the same table. At the same time, the locking
code assumes that that such locks are incompatible (for example, see check_locks()).
This doesn't lead to any problems other than warnings in error log for
debug builds of server since for InnoDB tables TL_READ_NO_INSERT type of
lock is only used for LOCK TABLES and for this statement InnoDB also
performs its own table-level locking.
Unfortunately, the table lock compatibility matrix cannot be updated to disallow
TL_READ_NO_INSERT when another thread holds TL_WRITE_ALLOW_WRITE without
causing starvation of LOCK TABLE READ in InnoDB under high write load.
This patch therefore contains no code changes.
The issue will be fixed later when LOCK TABLE READ has been updated
to not use table locks. This bug will therefore be marked as
"To be fixed later".
Code comment in thr_lock.c expanded to clarify the issue and a
test case based on the bug description added to innodb_mysql_lock.test.
Note that a global suppression rule has been added to both MTR v1 and v2
for the "Found lock of type 6 that is write and read locked" warning.
These suppression rules must be removed once this bug is properly fixed.
------------------------------------------------------------
revno: 2617.31.7
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: mysql-6.0-runtime
timestamp: Wed 2009-03-25 19:22:00 -0300
message:
WL#4284: Transactional DDL locking
Post-merge fixes for test cases.
mysql-test/include/mix1.inc:
Ignore deadlock errors due to the table being altered.
mysql-test/r/innodb_mysql.result:
Update test case result (WL$4284).
mysql-test/suite/parts/r/partition_special_innodb.result:
The INSERT and SELECT are not necessary to reproduce the
problem as the assertion happens when the table is being
altered.
Furthermore, the INSERT and SELECT will yield a deadlock
error as after the alter the table version is set to zero,
which means that any metadata locks on the table must be
relinquished, but this won't happen voluntarily in a
multi-statement transaction (metadata locks are released
on commit or rollback). Reported as Bug#43867.
mysql-test/suite/parts/t/partition_special_innodb.test:
The INSERT and SELECT are not necessary to reproduce the
problem as the assertion happens when the table is being
altered.
Furthermore, the INSERT and SELECT will yield a deadlock
error as after the alter the table version is set to zero,
which means that any metadata locks on the table must be
relinquished, but this won't happen voluntarily in a
multi-statement transaction (metadata locks are released
on commit or rollback). Reported as Bug#43867.
2617.31.12, 2617.31.15, 2617.31.15, 2617.31.16, 2617.43.1
- initial changeset that introduced the fix for
Bug#989 and follow up fixes for all test suite failures
introduced in the initial changeset.
------------------------------------------------------------
revno: 2617.31.1
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 4284-6.0
timestamp: Fri 2009-03-06 19:17:00 -0300
message:
Bug#989: If DROP TABLE while there's an active transaction, wrong binlog order
WL#4284: Transactional DDL locking
Currently the MySQL server does not keep metadata locks on
schema objects for the duration of a transaction, thus failing
to guarantee the integrity of the schema objects being used
during the transaction and to protect then from concurrent
DDL operations. This also poses a problem for replication as
a DDL operation might be replicated even thought there are
active transactions using the object being modified.
The solution is to defer the release of metadata locks until
a active transaction is either committed or rolled back. This
prevents other statements from modifying the table for the
entire duration of the transaction. This provides commitment
ordering for guaranteeing serializability across multiple
transactions.
- Incompatible change:
If MySQL's metadata locking system encounters a lock conflict,
the usual schema is to use the try and back-off technique to
avoid deadlocks -- this schema consists in releasing all locks
and trying to acquire them all in one go.
But in a transactional context this algorithm can't be utilized
as its not possible to release locks acquired during the course
of the transaction without breaking the transaction commitments.
To avoid deadlocks in this case, the ER_LOCK_DEADLOCK will be
returned if a lock conflict is encountered during a transaction.
Let's consider an example:
A transaction has two statements that modify table t1, then table
t2, and then commits. The first statement of the transaction will
acquire a shared metadata lock on table t1, and it will be kept
utill COMMIT to ensure serializability.
At the moment when the second statement attempts to acquire a
shared metadata lock on t2, a concurrent ALTER or DROP statement
might have locked t2 exclusively. The prescription of the current
locking protocol is that the acquirer of the shared lock backs off
-- gives up all his current locks and retries. This implies that
the entire multi-statement transaction has to be rolled back.
- Incompatible change:
FLUSH commands such as FLUSH PRIVILEGES and FLUSH TABLES WITH READ
LOCK won't cause locked tables to be implicitly unlocked anymore.
mysql-test/extra/binlog_tests/drop_table.test:
Add test case for Bug#989.
mysql-test/extra/binlog_tests/mix_innodb_myisam_binlog.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction.
mysql-test/include/mix1.inc:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction.
mysql-test/include/mix2.inc:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction.
mysql-test/r/flush_block_commit.result:
Update test case result (WL#4284).
mysql-test/r/flush_block_commit_notembedded.result:
Update test case result (WL#4284).
mysql-test/r/innodb.result:
Update test case result (WL#4284).
mysql-test/r/innodb_mysql.result:
Update test case result (WL#4284).
mysql-test/r/lock.result:
Add test case result for an effect of WL#4284/Bug#989
(all locks should be released when a connection terminates).
mysql-test/r/mix2_myisam.result:
Update test case result (effects of WL#4284/Bug#989).
mysql-test/r/not_embedded_server.result:
Update test case result (effects of WL#4284/Bug#989).
Add a test case for interaction of WL#4284 and FLUSH PRIVILEGES.
mysql-test/r/partition_innodb_semi_consistent.result:
Update test case result (effects of WL#4284/Bug#989).
mysql-test/r/partition_sync.result:
Temporarily disable the test case for Bug#43867,
which will be fixed by a subsequent backport.
mysql-test/r/ps.result:
Add a test case for effect of PREPARE on transactional
locks: we take a savepoint at beginning of PREAPRE
and release it at the end. Thus PREPARE does not
accumulate metadata locks (Bug#989/WL#4284).
mysql-test/r/read_only_innodb.result:
Update test case result (effects of WL#4284/Bug#989).
mysql-test/suite/binlog/r/binlog_row_drop_tbl.result:
Add a test case result (WL#4284/Bug#989).
mysql-test/suite/binlog/r/binlog_row_mix_innodb_myisam.result:
Update test case result (effects of WL#4284/Bug#989).
mysql-test/suite/binlog/r/binlog_stm_drop_tbl.result:
Add a test case result (WL#4284/Bug#989).
mysql-test/suite/binlog/r/binlog_stm_mix_innodb_myisam.result:
Update test case result (effects of WL#4284/Bug#989).
mysql-test/suite/binlog/r/binlog_unsafe.result:
A side effect of Bug#989 -- slightly different table map ids.
mysql-test/suite/binlog/t/binlog_row_drop_tbl.test:
Add a test case for WL#4284/Bug#989.
mysql-test/suite/binlog/t/binlog_stm_drop_tbl.test:
Add a test case for WL#4284/Bug#989.
mysql-test/suite/binlog/t/binlog_stm_row.test:
Update to the new state name. This
is actually a follow up to another patch for WL#4284,
that changes Locked thread state to Table lock.
mysql-test/suite/ndb/r/ndb_index_ordered.result:
Remove result for disabled part of the test case.
mysql-test/suite/ndb/t/disabled.def:
Temporarily disable a test case (Bug#45621).
mysql-test/suite/ndb/t/ndb_index_ordered.test:
Disable a part of a test case (needs update to
reflect semantics of Bug#989).
mysql-test/suite/rpl/t/disabled.def:
Disable tests made meaningless by transactional metadata
locking.
mysql-test/suite/sys_vars/r/autocommit_func.result:
Add a commit (Bug#989).
mysql-test/suite/sys_vars/t/autocommit_func.test:
Add a commit (Bug#989).
mysql-test/t/flush_block_commit.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction.
mysql-test/t/flush_block_commit_notembedded.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction.
Add a test case for transaction-scope locks and the global
read lock (Bug#989/WL#4284).
mysql-test/t/innodb.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction
(effects of Bug#989/WL#4284).
mysql-test/t/lock.test:
Add a test case for Bug#989/WL#4284.
mysql-test/t/not_embedded_server.test:
Add a test case for Bug#989/WL#4284.
mysql-test/t/partition_innodb_semi_consistent.test:
Replace TRUNCATE with DELETE, to not issue
an implicit commit of a transaction, and not depend
on metadata locks.
mysql-test/t/partition_sync.test:
Temporarily disable the test case for Bug#43867,
which needs a fix to be backported from 6.0.
mysql-test/t/ps.test:
Add a test case for semantics of PREPARE and transaction-scope
locks: metadata locks on tables used in PREPARE are enclosed into a
temporary savepoint, taken at the beginning of PREPARE,
and released at the end. Thus PREPARE does not effect
what locks a transaction owns.
mysql-test/t/read_only_innodb.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction
(Bug#989/WL#4284).
Wait for the read_only statement to actually flush tables before
sending other concurrent statements that depend on its state.
mysql-test/t/xa.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction
(Bug#989/WL#4284).
sql/ha_ndbcluster_binlog.cc:
Backport bits of changes of ha_ndbcluster_binlog.cc
from 6.0, to fix the failing binlog test suite with
WL#4284. WL#4284 implementation does not work
with 5.1 implementation of ndbcluster binlog index.
sql/log_event.cc:
Release metadata locks after issuing a commit.
sql/mdl.cc:
Style changes (WL#4284).
sql/mysql_priv.h:
Rename parameter to match the name used in the definition (WL#4284).
sql/rpl_injector.cc:
Release metadata locks on commit (WL#4284).
sql/rpl_rli.cc:
Remove assert made meaningless, metadata locks are released
at the end of the transaction.
sql/set_var.cc:
Close tables and release locks if autocommit mode is set.
sql/slave.cc:
Release metadata locks after a rollback.
sql/sql_acl.cc:
Don't implicitly unlock locked tables. Issue a implicit commit
at the end and unlock tables.
sql/sql_base.cc:
Defer the release of metadata locks when closing tables
if not required to.
Issue a deadlock error if the locking protocol requires
that a transaction re-acquire its locks.
Release metadata locks when closing tables for reopen.
sql/sql_class.cc:
Release metadata locks if the thread is killed.
sql/sql_parse.cc:
Release metadata locks after implicitly committing a active
transaction, or after explicit commits or rollbacks.
sql/sql_plugin.cc:
Allocate MDL request on the stack as the use of the table
is contained within the function. It will be removed from
the context once close_thread_tables is called at the end
of the function.
sql/sql_prepare.cc:
The problem is that the prepare phase of the CREATE TABLE
statement takes a exclusive metadata lock lock and this can
cause a self-deadlock the thread already holds a shared lock
on the table being that should be created.
The solution is to make the prepare phase take a shared
metadata lock when preparing a CREATE TABLE statement. The
execution of the statement will still acquire a exclusive
lock, but won't cause any problem as it issues a implicit
commit.
After some discussions with stakeholders it has been decided that
metadata locks acquired during a PREPARE statement must be released
once the statement is prepared even if it is prepared within a multi
statement transaction.
sql/sql_servers.cc:
Don't implicitly unlock locked tables. Issue a implicit commit
at the end and unlock tables.
sql/sql_table.cc:
Close table and release metadata locks after a admin operation.
sql/table.h:
The problem is that the prepare phase of the CREATE TABLE
statement takes a exclusive metadata lock lock and this can
cause a self-deadlock the thread already holds a shared lock
on the table being that should be created.
The solution is to make the prepare phase take a shared
metadata lock when preparing a CREATE TABLE statement. The
execution of the statement will still acquire a exclusive
lock, but won't cause any problem as it issues a implicit
commit.
sql/transaction.cc:
Release metadata locks after the implicitly committed due
to a new transaction being started. Also, release metadata
locks acquired after a savepoint if the transaction is rolled
back to the save point.
The problem is that in some cases transaction-long metadata locks
could be released before the transaction was committed. This could
happen when a active transaction was ended by a "START TRANSACTION"
or "BEGIN" statement, in which case the metadata locks would be
released before the actual commit of the active transaction.
The solution is to defer the release of metadata locks to after the
transaction has been implicitly committed. No test case is provided
as the effort to provide one is too disproportional to the size of
the fix.
------------------------------------------------------------
revno: 2630.13.16
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: WL#4284
timestamp: Sat 2008-07-26 13:38:20 -0300
message:
WL#4284: Transactional DDL locking
SQL statements' effect on transactions.
Currently the MySQL server and its storage engines are not
capable of rolling back operations that define or modify data
structures (also known as DDL statements) or operations that
alter any of the system tables (the mysql database). Allowing
these group of statements to participate in transactions
is unfeasible at this time (since rollback has no effect
whatsoever on them) and goes against the design of our metadata
locking subsystem.
The solution is to issue implicit commits before and after
those statements execution. This effectively confines each of
those statements to its own special transaction and ensures
that metadata locks taken during this special transaction
are not leaked into posterior statements/transactions.
mysql-test/include/commit.inc:
Alter table rename was not committing the normal transaction at the
end of its execution, and as a consequence, the commit was being
issued in the next DDL command (rename table) that happened to end
the active transaction. Other changes are to take into account the
implicit commits issued before and after the DDL command execution.
mysql-test/include/implicit_commit_helper.inc:
Add auxiliary test that shows if a statement issued a
implicit commit.
mysql-test/r/commit_1innodb.result:
Update test case result.
mysql-test/r/implicit_commit.result:
Test implicit commit behavior of some SQL commands.
mysql-test/t/implicit_commit.test:
Test implicit commit behavior of some SQL commands.
sql/events.cc:
Transaction is now ended before the command execution.
sql/mysql_priv.h:
Add flags array for server commands and remove historical
left over.
sql/sql_class.h:
Add flags to control when to issue implicit commits before and
after a command execution.
sql/sql_delete.cc:
A implicit commit is issued at the end of truncate
statements.
sql/sql_parse.cc:
Mark commands that need implicit commits before and
after their executions. The implicit commits of the
statement and the normal transaction are now issued
regardless of the user access privileges.
sql/sql_table.cc:
A implicit commit is now issued before admin commands.
tests/mysql_client_test.c:
Test that COM_REFRESH issues a implicit commit.
The original test case was lost when
merging WL#4571.
Added the testcase.
mysql-test/include/check_key_reads.inc:
Bug#49369: No testcase for key caches on partitions
New include file for testing key caches on partitions
WL#4571
mysql-test/include/check_key_req.inc:
Bug#49369: No testcase for key caches on partitions
New include file for testing key caches on partitions
WL#4571
mysql-test/r/partition_key_cache.result:
Bug#49369: No testcase for key caches on partitions
New test case for testing key caches on partitions
WL#4571
mysql-test/t/partition_key_cache.test:
Bug#49369: No testcase for key caches on partitions
New test case for testing key caches on partitions
WL#4571
Text conflict in mysql-test/collections/default.experimental
Text conflict in mysql-test/r/show_check.result
Text conflict in mysql-test/r/sp-code.result
Text conflict in mysql-test/suite/binlog/r/binlog_tmp_table.result
Text conflict in mysql-test/suite/rpl/t/disabled.def
Text conflict in mysql-test/t/show_check.test
Text conflict in mysys/my_delete.c
Text conflict in sql/item.h
Text conflict in sql/item_cmpfunc.h
Text conflict in sql/log.cc
Text conflict in sql/mysqld.cc
Text conflict in sql/repl_failsafe.cc
Text conflict in sql/slave.cc
Text conflict in sql/sql_parse.cc
Text conflict in sql/sql_table.cc
Text conflict in sql/sql_yacc.yy
Text conflict in storage/myisam/ha_myisam.cc
Corrected results for
stm_auto_increment_bug33029.reject 2009-12-01
20:01:49.000000000 +0300
<andrei> @@ -42,9 +42,6 @@
<andrei> RETURN i;
<andrei> END//
<andrei> CALL p1();
<andrei> -Warnings:
<andrei> -Note 1592 Statement may not be safe to log in statement
format.
<andrei> -Note 1592 Statement may not be safe to log in statement
format.
There should be indeed no Note present because there is in fact autoincrement
top-level query in sp() that triggers inserting in yet another auto-inc table.
(todo: alert DaoGang to improve the test).
Backport of:
------------------------------------------------------------
revno: 2630.4.1
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Fri 2008-05-23 17:54:03 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After review fixes in progress.
------------------------------------------------------------
This is the first patch in series. It transforms the metadata
locking subsystem to use a dedicated module (mdl.h,cc). No
significant changes in the locking protocol.
The import passes the test suite with the exception of
deprecated/removed 6.0 features, and MERGE tables. The latter
are subject to a fix by WL#4144.
Unfortunately, the original changeset comments got lost in a merge,
thus this import has its own (largely insufficient) comments.
This patch fixes Bug#25144 "replication / binlog with view breaks".
Warning: this patch introduces an incompatible change:
Under LOCK TABLES, it's no longer possible to FLUSH a table that
was not locked for WRITE.
Under LOCK TABLES, it's no longer possible to DROP a table or
VIEW that was not locked for WRITE.
******
Backport of:
------------------------------------------------------------
revno: 2630.4.2
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Sat 2008-05-24 14:03:45 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After review fixes in progress.
******
Backport of:
------------------------------------------------------------
revno: 2630.4.3
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Sat 2008-05-24 14:08:51 +0400
message:
WL#3726 "DDL locking for all metadata objects"
Fixed failing Windows builds by adding mdl.cc to the lists
of files needed to build server/libmysqld on Windows.
******
Backport of:
------------------------------------------------------------
revno: 2630.4.4
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Sat 2008-05-24 21:57:58 +0400
message:
WL#3726 "DDL locking for all metadata objects".
Fix for assert failures in kill.test which occured when one
tried to kill ALTER TABLE statement on merge table while it
was waiting in wait_while_table_is_used() for other connections
to close this table.
These assert failures stemmed from the fact that cleanup code
in this case assumed that temporary table representing new
version of table was open with adding to THD::temporary_tables
list while code which were opening this temporary table wasn't
always fulfilling this.
This patch changes code that opens new version of table to
always do this linking in. It also streamlines cleanup process
for cases when error occurs while we have new version of table
open.
******
WL#3726 "DDL locking for all metadata objects"
Add libmysqld/mdl.cc to .bzrignore.
******
Backport of:
------------------------------------------------------------
revno: 2630.4.6
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Sun 2008-05-25 00:33:22 +0400
message:
WL#3726 "DDL locking for all metadata objects".
Addition to the fix of assert failures in kill.test caused by
changes for this worklog.
Make sure we close the new table only once.
.bzrignore:
Add libmysqld/mdl.cc
libmysqld/CMakeLists.txt:
Added mdl.cc to the list of files needed for building of libmysqld.
libmysqld/Makefile.am:
Added files implementing new meta-data locking subsystem to the server.
mysql-test/include/handler.inc:
Use separate connection for waiting while threads performing DDL
operations conflicting with open HANDLER tables reach blocked
state. This is required because now we check and close tables open
by HANDLER statements in this connection conflicting with DDL in
another each time open_tables() is called and thus select from I_S
which is used for waiting will unblock DDL operations if issued
from connection with open HANDLERs.
mysql-test/r/create.result:
Adjusted test case after change in implementation of CREATE TABLE
... SELECT. We no longer have special check in open_table() which
catches the case when we select from the table created. Instead we
rely on unique_table() call which happens after opening and
locking all tables.
mysql-test/r/flush.result:
FLUSH TABLES WITH READ LOCK can no longer happen under LOCK
TABLES. Updated test accordingly.
mysql-test/r/flush_table.result:
Under LOCK TABLES we no longer allow to do FLUSH TABLES for tables
locked for read. Updated test accordingly.
mysql-test/r/handler_innodb.result:
Use separate connection for waiting while threads performing DDL
operations conflicting with open HANDLER tables reach blocked
state. This is required because now we check and close tables open
by HANDLER statements in this connection conflicting with DDL in
another each time open_tables() is called and thus select from I_S
which is used for waiting will unblock DDL operations if issued
from connection with open HANDLERs.
mysql-test/r/handler_myisam.result:
Use separate connection for waiting while threads performing DDL
operations conflicting with open HANDLER tables reach blocked
state. This is required because now we check and close tables open
by HANDLER statements in this connection conflicting with DDL in
another each time open_tables() is called and thus select from I_S
which is used for waiting will unblock DDL operations if issued
from connection with open HANDLERs.
mysql-test/r/information_schema.result:
Additional test for WL#3726 "DDL locking for all metadata
objects". Check that we use high-priority metadata lock requests
when filling I_S tables.
Rearrange tests to match 6.0 better (fewer merge conflicts).
mysql-test/r/kill.result:
Added tests checking that DDL and DML statements waiting for
metadata locks can be interrupted by KILL command.
mysql-test/r/lock.result:
One no longer is allowed to do DROP VIEW under LOCK TABLES even if
this view is locked by LOCK TABLES. The problem is that in such
situation write locks on view are not mutually exclusive so
upgrading metadata lock which is required for dropping of view
will lead to deadlock.
mysql-test/r/partition_column_prune.result:
Update results (same results in 6.0), WL#3726
mysql-test/r/partition_pruning.result:
Update results (same results in 6.0), WL#3726
mysql-test/r/ps_ddl.result:
We no longer invalidate prepared CREATE TABLE ... SELECT statement
if target table changes. This is OK since it is not strictly
necessary.
The first change is wrong, is caused by FLUSH TABLE
now flushing all unused tables. This is a regression that
Dmitri fixed in 6.0 in a follow up patch.
mysql-test/r/sp.result:
Under LOCK TABLES we no longer allow accessing views which were
not explicitly locked. To access view we need to obtain metadata
lock on it and doing this under LOCK TABLES may lead to deadlocks.
mysql-test/r/view.result:
One no longer is allowed to do DROP VIEW under LOCK TABLES even if
this view is locked by LOCK TABLES. The problem is that in such
situation even "write locks" on view are not mutually exclusive so
upgrading metadata lock which is required for dropping of view
will lead to deadlock
mysql-test/r/view_grant.result:
ALTER VIEW implementation was changed to open a view only after
checking that user which does alter has appropriate privileges on
it. This means that in case when user's privileges are
insufficient for this we won't check that new view definer is the
same as original one or user performing alter has SUPER privilege.
Adjusted test case accordingly.
mysql-test/r/view_multi.result:
Added test case for bug#25144 "replication / binlog with view
breaks".
mysql-test/suite/rpl/t/disabled.def:
Disable test for deprecated features (they don't work with new MDL).
mysql-test/t/create.test:
Adjusted test case after change in implementation of CREATE TABLE
... SELECT. We no longer have special check in open_table() which
catches the case when we select from the table created. Instead we
rely on unique_table() call which happens after opening and
locking all tables.
mysql-test/t/disabled.def:
Disable merge.test, subject of WL#4144
mysql-test/t/flush.test:
FLUSH TABLES WITH READ LOCK can no longer happen under LOCK
TABLES. Updated test accordingly.
mysql-test/t/flush_table.test:
Under LOCK TABLES we no longer allow to do FLUSH TABLES for tables
locked for read. Updated test accordingly.
mysql-test/t/information_schema.test:
Additional test for WL#3726 "DDL locking for all metadata
objects". Check that we use high-priority metadata lock requests
when filling I_S tables.
Rearrange the results for easier merges with 6.0.
mysql-test/t/kill.test:
Added tests checking that DDL and DML statements waiting for
metadata locks can be interrupted by KILL command.
mysql-test/t/lock.test:
One no longer is allowed to do DROP VIEW under LOCK TABLES even if
this view is locked by LOCK TABLES. The problem is that in such
situation write locks on view are not mutually exclusive so
upgrading metadata lock which is required for dropping of view
will lead to deadlock.
mysql-test/t/lock_multi.test:
Adjusted test case to the changes of status in various places
caused by change in implementation FLUSH TABLES WITH READ LOCK,
which is now takes global metadata lock before flushing tables and
therefore waits on at these places.
mysql-test/t/ps_ddl.test:
We no longer invalidate prepared CREATE TABLE ... SELECT statement
if target table changes. This is OK since it is not strictly
necessary.
The first change is wrong, is caused by FLUSH TABLE
now flushing all unused tables. This is a regression that
Dmitri fixed in 6.0 in a follow up patch.
mysql-test/t/sp.test:
Under LOCK TABLES we no longer allow accessing views which were
not explicitly locked. To access view we need to obtain metadata
lock on it and doing this under LOCK TABLES may lead to deadlocks.
mysql-test/t/trigger_notembedded.test:
Adjusted test case to the changes of status in various places
caused by change in implementation FLUSH TABLES WITH READ LOCK,
which is now takes global metadata lock before flushing tables and
therefore waits on at these places.
mysql-test/t/view.test:
One no longer is allowed to do DROP VIEW under LOCK TABLES even if
this view is locked by LOCK TABLES. The problem is that in such
situation even "write locks" on view are not mutually exclusive so
upgrading metadata lock which is required for dropping of view
will lead to deadlock.
mysql-test/t/view_grant.test:
ALTER VIEW implementation was changed to open a view only after
checking that user which does alter has appropriate privileges on
it. This means that in case when user's privileges are
insufficient for this we won't check that new view definer is the
same as original one or user performing alter has SUPER privilege.
Adjusted test case accordingly.
mysql-test/t/view_multi.test:
Added test case for bug#25144 "replication / binlog with view
breaks".
sql/CMakeLists.txt:
Added mdl.cc to the list of files needed for building of server.
sql/Makefile.am:
Added files implementing new meta-data locking subsystem to the
server.
sql/event_db_repository.cc:
Allocate metadata lock requests objects (MDL_LOCK) on execution
memory root in cases when TABLE_LIST objects is also allocated
there or on stack.
sql/ha_ndbcluster.cc:
Adjusted code to work nicely with new metadata locking subsystem.
close_cached_tables() no longer has wait_for_placeholder argument.
Instead of relying on this parameter and related behavior FLUSH
TABLES WITH READ LOCK now takes global shared metadata lock.
sql/ha_ndbcluster_binlog.cc:
Adjusted code to work with new metadata locking subsystem.
close_cached_tables() no longer has wait_for_placeholder argument.
Instead of relying on this parameter and related behavior FLUSH
TABLES WITH READ LOCK now takes global shared metadata lock.
sql/handler.cc:
update_frm_version():
Directly update TABLE_SHARE::mysql_version member instead of
going through all TABLE instances for this table (old code was a
legacy from pre-table-definition-cache days).
sql/lock.cc:
Use new metadata locking subsystem. Threw away most of functions
related to name locking as now one is supposed to use metadata
locking API instead. In lock_global_read_lock() and
unlock_global_read_lock() in order to avoid problems with global
read lock sneaking in at the moment when we perform FLUSH TABLES
or ALTER TABLE under LOCK TABLES and when tables being reopened
are protected only by metadata locks we also have to take global
shared meta data lock.
sql/log_event.cc:
Adjusted code to work with new metadata locking subsystem. For
tables open by slave thread for applying RBR events allocate
memory for lock request object in the same chunk of memory as
TABLE_LIST objects for them. In order to ensure that we keep these
objects around until tables are open always close tables before
calling Relay_log_info::clear_tables_to_lock(). Use new auxiliary
Relay_log_info::slave_close_thread_tables() method to enforce
this.
sql/log_event_old.cc:
Adjusted code to work with new metadata locking subsystem. Since
for tables open by slave thread for applying RBR events memory for
lock request object is allocated in the same chunk of memory as
TABLE_LIST objects for them we have to ensure that we keep these
objects around until tables are open. To ensure this we always
close tables before calling
Relay_log_info::clear_tables_to_lock(). To enfore this we use
new auxiliary Relay_log_info::slave_close_thread_tables()
method.
sql/mdl.cc:
Implemented new metadata locking subsystem and API described in
WL3726 "DDL locking for all metadata objects".
sql/mdl.h:
Implemented new metadata locking subsystem and API described in
WL3726 "DDL locking for all metadata objects".
sql/mysql_priv.h:
- close_thread_tables()/close_tables_for_reopen() now has one more
argument which indicates that metadata locks should be released
but not removed from the context in order to be used later in
mdl_wait_for_locks() and tdc_wait_for_old_version().
- close_cached_table() routine is no longer public.
- Thread waiting in wait_while_table_is_used() can be now killed
so this function returns boolean to make caller aware of such
situation.
- We no longer have table cache as separate entity instead used
and unused TABLE instances are linked to TABLE_SHARE objects in
table definition cache.
- Now third argument of open_table() is also used for requesting
table repair or auto-discovery of table's new definition. So its
type was changed from bool to enum.
- Added tdc_open_view() function for opening view by getting its
definition from disk (and table cache in future).
- reopen_name_locked_table() no longer needs "link_in" argument as
now we have exclusive metadata locks instead of dummy TABLE
instances when this function is called.
- find_locked_table() now takes head of list of TABLE instances
instead of always scanning through THD::open_tables list. Also
added find_write_locked_table() auxiliary.
- reopen_tables(), close_cached_tables() no longer have
mark_share_as_old and wait_for_placeholder arguments. Instead of
relying on this parameters and related behavior FLUSH TABLES
WITH READ LOCK now takes global shared metadata lock.
- We no longer need drop_locked_tables() and
abort_locked_tables().
- mysql_ha_rm_tables() now always assume that LOCK_open is not
acquired by caller.
- Added notify_thread_having_shared_lock() callback invoked by
metadata locking subsystem when acquiring an exclusive lock, for
each thread that has a conflicting shared metadata lock.
- Introduced expel_table_from_cache() as replacement for
remove_table_from_cache() (the main difference is that this new
function assumes that caller follows metadata locking protocol
and never waits).
- Threw away most of functions related to name locking. One should
use new metadata locking subsystem and API instead.
sql/mysqld.cc:
Got rid of call initializing/deinitializing table cache since now
it is embedded into table definition cache. Added calls for
initializing/ deinitializing metadata locking subsystem.
sql/rpl_rli.cc:
Introduced auxiliary Relay_log_info::slave_close_thread_tables()
method which is used for enforcing that we always close tables
open for RBR before deallocating TABLE_LIST elements and MDL_LOCK
objects for them.
sql/rpl_rli.h:
Introduced auxiliary Relay_log_info::slave_close_thread_tables()
method which is used for enforcing that we always close tables
open for RBR before deallocating TABLE_LIST elements and MDL_LOCK
objects for them.
sql/set_var.cc:
close_cached_tables() no longer has wait_for_placeholder argument.
Instead of relying on this parameter and related behavior FLUSH
TABLES WITH READ LOCK now takes global shared metadata lock.
sql/sp_head.cc:
For tables added to the statement's table list by prelocking
algorithm we allocate these objects either on the same memory as
corresponding table list elements or on THD::locked_tables_root
(if we are building table list for LOCK TABLES).
sql/sql_acl.cc:
Allocate metadata lock requests objects (MDL_LOCK) on execution
memory root in cases when we use stack TABLE_LIST objects to open
tables. Got rid of redundant code by using unlock_locked_tables()
function.
sql/sql_base.cc:
Changed code to use new MDL subsystem. Got rid of separate table
cache. Now used and unused TABLE instances are linked to the
TABLE_SHAREs in table definition cache.
check_unused():
Adjusted code to the fact that we no longer have separate table
cache. Removed dead code.
table_def_free():
Free TABLE instances referenced from TABLE_SHARE objects before
destroying table definition cache.
get_table_share():
Added assert which ensures that noone will be able to access
table (and its share) without acquiring some kind of metadata
lock first.
close_handle_and_leave_table_as_lock():
Adjusted code to the fact that TABLE instances now are linked to
list in TABLE_SHARE.
list_open_tables():
Changed this function to use table definition cache instead of
table cache.
free_cache_entry():
Unlink freed TABLE elements from the list of all TABLE instances
for the table in TABLE_SHARE.
kill_delayed_thread_for_table():
Added auxiliary for killing delayed insert threads for
particular table.
close_cached_tables():
Got rid of wait_for_refresh argument as we now rely on global
shared metadata lock to prevent FLUSH WITH READ LOCK sneaking in
when we are reopening tables. Heavily reworked this function to
use new MDL code and not to rely on separate table cache entity.
close_open_tables():
We no longer have separate table cache.
close_thread_tables():
Release metadata locks after closing all tables. Added skip_mdl
argument which allows us not to remove metadata lock requests
from the context in case when we are going to use this requests
later in mdl_wait_for_locks() and tdc_wait_for_old_versions().
close_thread_table()/close_table_for_reopen():
Since we no longer have separate table cache and all TABLE
instances are linked to TABLE_SHARE objects in table definition
cache we have to link/unlink TABLE object to/from appropriate
lists in the share.
name_lock_locked_table():
Moved redundant code to find_write_locked_table() function and
adjusted code to the fact that wait_while_table_is_used() can
now return with an error if our thread is killed.
reopen_table_entry():
We no longer need "link_in" argument as with MDL we no longer
call this function with dummy TABLE object pre-allocated and
added to the THD::open_tables. Also now we add newly-open TABLE
instance to the list of share's used TABLE instances.
table_cache_insert_placeholder():
Got rid of name-locking legacy.
lock_table_name_if_not_cached():
Moved to sql_table.cc the only place where it is used. It was
also reimplemented using new MDL API.
open_table():
- Reworked this function to use new MDL subsystem.
- Changed code to deal with table definition cache directly
instead of going through separate table cache.
- Now third argument is also used for requesting table repair
or auto-discovery of table's new definition. So its type was
changed from bool to enum.
find_locked_table()/find_write_locked_table():
Accept head of list of TABLE objects as first argument and use
this list instead of always searching in THD::open_tables list.
Also added auxiliary for finding write-locked locked tables.
reopen_table():
Adjusted function to work with new MDL subsystem and to properly
manuipulate with lists of used/unused TABLE instaces in
TABLE_SHARE.
reopen_tables():
Removed mark_share_as_old parameter. Instead of relying on it
and related behavior FLUSH TABLES WITH READ LOCK now takes
global shared metadata lock. Changed code after removing
separate table cache.
drop_locked_tables()/abort_locked_tables():
Got rid of functions which are no longer needed.
unlock_locked_tables():
Moved this function from sql_parse.cc and changed it to release
memory which was used for allocating metadata lock requests for
tables open and locked by LOCK TABLES.
tdc_open_view():
Intoduced function for opening a view by getting its definition
from disk (and table cache in future).
reopen_table_entry():
Introduced function for opening table definitions while holding
exclusive metatadata lock on it.
open_unireg_entry():
Got rid of this function. Most of its functionality is relocated
to open_table() and open_table_fini() functions, and some of it
to reopen_table_entry() and tdc_open_view(). Also code
resposible for auto-repair and auto-discovery of tables was
moved to separate function.
open_table_entry_fini():
Introduced function which contains common actions which finalize
process of TABLE object creation.
auto_repair_table():
Moved code responsible for auto-repair of table being opened
here.
handle_failed_open_table_attempt()
Moved code responsible for handling failing attempt to open
table to one place (retry due to lock conflict/old version,
auto-discovery and repair).
open_tables():
- Flush open HANDLER tables if they have old version of if there
is conflicting metadata lock against them (before this moment
we had this code in open_table()).
- When we open view which should be processed via derived table
on the second execution of prepared statement or stored
routine we still should call open_table() for it in order to
obtain metadata lock on it and prepare its security context.
- In cases when we discover that some special handling of
failure to open table is needed call
handle_failed_open_table_attempt() which handles all such
scenarios.
open_ltable():
Handling of various special scenarios of failure to open a table
was moved to separate handle_failed_open_table_attempt()
function.
remove_db_from_cache():
Removed this function as it is no longer used.
notify_thread_having_shared_lock():
Added callback which is invoked by MDL subsystem when acquiring
an exclusive lock, for each thread that has a conflicting shared
metadata lock.
expel_table_from_cache():
Introduced function for removing unused TABLE instances. Unlike
remove_table_from_cache() it relies on caller following MDL
protocol and having appropriate locks when calling it and thus
does not do any waiting if table is still in use.
tdc_wait_for_old_version():
Added function which allows open_tables() to wait in cases when
we discover that we should back-off due to presence of old
version of table.
abort_and_upgrade_lock():
Use new MDL calls.
mysql_wait_completed_table():
Got rid of unused function.
open_system_tables_for_read/for_update()/performance_schema_table():
Allocate MDL_LOCK objects on execution memory root in cases when
TABLE_LIST objects for corresponding tables is allocated on
stack.
close_performance_schema_table():
Release metadata locks after closing tables.
******
Use I_P_List for free/used tables list in the table share.
sql/sql_binlog.cc:
Use Relay_log_info::slave_close_thread_tables() method to enforce
that we always close tables open for RBR before deallocating
TABLE_LIST elements and MDL_LOCK objects for them.
sql/sql_class.cc:
Added meta-data locking contexts as part of Open_tables_state
context. Also introduced THD::locked_tables_root memory root
which is to be used for allocating MDL_LOCK objects for tables in
LOCK TABLES statement (end of lifetime for such objects is UNLOCK
TABLES so we can't use statement or execution root for them).
sql/sql_class.h:
Added meta-data locking contexts as part of Open_tables_state
context. Also introduced THD::locked_tables_root memory root
which is to be used for allocating MDL_LOCK objects for tables in
LOCK TABLES statement (end of lifetime for such objects is UNLOCK
TABLES so we can't use statement or execution root for them).
Note: handler_mdl_context and locked_tables_root and
mdl_el_root will be removed by subsequent patches.
sql/sql_db.cc:
mysql_rm_db() does not really need to call remove_db_from_cache()
as it drops each table in the database using
mysql_rm_table_part2(), which performs all necessary operations on
table (definition) cache.
sql/sql_delete.cc:
Use the new metadata locking API for TRUNCATE.
sql/sql_handler.cc:
Changed HANDLER implementation to use new metadata locking
subsystem. Note that MDL_LOCK objects for HANDLER tables are
allocated in the same chunk of heap memory as TABLE_LIST object
for those tables.
sql/sql_insert.cc:
mysql_insert():
find_locked_table() now takes head of list of TABLE object as
its argument instead of always scanning through THD::open_tables
list.
handle_delayed_insert():
Allocate metadata lock request object for table open by delayed
insert thread on execution memroot. create_table_from_items():
We no longer allocate dummy TABLE objects for tables being
created if they don't exist. As consequence
reopen_name_locked_table() no longer has link_in argument.
open_table() now has one more argument which is not relevant for
temporary tables.
sql/sql_parse.cc:
- Moved unlock_locked_tables() routine to sql_base.cc and made
available it in other files. Got rid of some redundant code by
using this function.
- Replaced boolean TABLE_LIST::create member with enum
open_table_type member.
- Use special memory root for allocating MDL_LOCK objects for
tables open and locked by LOCK TABLES (these object should live
till UNLOCK TABLES so we can't allocate them on statement nor
execution memory root). Also properly set metadata lock
upgradability attribure for those tables.
- Under LOCK TABLES it is no longer allowed to flush tables which
are not write-locked as this breaks metadata locking protocol
and thus potentially might lead to deadlock.
- Added auxiliary adjust_mdl_locks_upgradability() function.
sql/sql_partition.cc:
Adjusted code to the fact that reopen_tables() no longer has
"mark_share_as_old" argument. Got rid of comments which are no
longer true.
sql/sql_plist.h:
Added I_P_List template class for parametrized intrusive doubly
linked lists and I_P_List_iterator for corresponding iterator.
Unlike for I_List<> list elements of such list can participate in
several lists. Unlike List<> such lists are doubly-linked and
intrusive.
sql/sql_plugin.cc:
Allocate metadata lock requests objects (MDL_LOCK) on execution
memory root in cases when we use stack TABLE_LIST objects to open
tables.
sql/sql_prepare.cc:
Replaced boolean TABLE_LIST::create member with enum
open_table_type member. This allows easily handle situation in
which instead of opening the table we want only to take exclusive
metadata lock on it.
sql/sql_rename.cc:
Use new metadata locking subsystem in implementation of RENAME
TABLE.
sql/sql_servers.cc:
Allocate metadata lock requests objects (MDL_LOCK) on execution
memory root in cases when we use stack TABLE_LIST objects to open
tables. Got rid of redundant code by using unlock_locked_tables()
function.
sql/sql_show.cc:
Acquire shared metadata lock when we are getting information for
I_S table directly from TABLE_SHARE without doing full-blown table
open. We use high priority lock request in this situation in
order to avoid deadlocks.
Also allocate metadata lock requests objects (MDL_LOCK) on
execution memory root in cases when TABLE_LIST objects are also
allocated there
sql/sql_table.cc:
mysql_rm_table():
Removed comment which is no longer relevant.
mysql_rm_table_part2():
Now caller of mysql_ha_rm_tables() should not own LOCK_open.
Adjusted code to use new metadata locking subsystem instead of
name-locks.
lock_table_name_if_not_cached():
Moved this function from sql_base.cc to this file and
reimplemented it using metadata locking API.
mysql_create_table():
Adjusted code to use new MDL API.
wait_while_table_is_used():
Changed function to use new MDL subsystem. Made thread waiting
in it killable (this also led to introduction of return value so
caller can distinguish successful executions from situations
when waiting was aborted).
close_cached_tables():
Thread waiting in this function is killable now. As result it
has return value for distinguishing between succes and failure.
Got rid of redundant boradcast_refresh() call.
prepare_for_repair():
Use MDL subsystem instead of name-locks.
mysql_admin_table():
mysql_ha_rm_tables() now always assumes that caller doesn't own
LOCK_open.
mysql_repair_table():
We should mark all elements of table list as requiring
upgradable metadata locks.
mysql_create_table_like():
Use new MDL subsystem instead of name-locks.
create_temporary_tables():
We don't need to obtain metadata locks when creating temporary
table.
mysql_fast_or_online_alter_table():
Thread waiting in wait_while_table_is_used() is now killable.
mysql_alter_table():
Adjusted code to work with new MDL subsystem and to the fact
that threads waiting in what_while_table_is_used() and
close_cached_table() are now killable.
sql/sql_test.cc:
We no longer have separate table cache. TABLE instances are now
associated with/linked to TABLE_SHARE objects in table definition
cache.
sql/sql_trigger.cc:
Adjusted code to work with new metadata locking subsystem. Also
reopen_tables() no longer has mark_share_as_old argument (Instead
of relying on this parameter and related behavior FLUSH TABLES
WITH READ LOCK now takes global shared metadata lock).
sql/sql_udf.cc:
Allocate metadata lock requests objects (MDL_LOCK) on execution
memory root in cases when we use stack TABLE_LIST objects to open
tables.
sql/sql_update.cc:
Adjusted code to work with new meta-data locking subsystem.
sql/sql_view.cc:
Added proper meta-data locking to implementations of
CREATE/ALTER/DROP VIEW statements. Now we obtain exclusive
meta-data lock on a view before creating/ changing/dropping it.
This ensures that all concurrent statements that use this view
will finish before our statement will proceed and therefore we
will get correct order of statements in the binary log.
Also ensure that TABLE_LIST::mdl_upgradable attribute is properly
propagated for underlying tables of view.
sql/table.cc:
Added auxiliary alloc_mdl_locks() function for allocating metadata
lock request objects for all elements of table list.
sql/table.h:
TABLE_SHARE:
Got rid of unused members. Introduced members for storing lists
of used and unused TABLE objects for this share.
TABLE:
Added members for linking TABLE objects into per-share lists of
used and unused TABLE instances. Added member for holding
pointer to metadata lock for this table.
TABLE_LIST:
Replaced boolean TABLE_LIST::create member with enum
open_table_type member. This allows easily handle situation in
which instead of opening the table we want only to take
exclusive meta-data lock on it (we need this in order to handle
ALTER VIEW and CREATE VIEW statements).
Introduced new mdl_upgradable member for marking elements of
table list for which we need to take upgradable shared metadata
lock instead of plain shared metadata lock. Added pointer for
holding pointer to MDL_LOCK for the table.
Added auxiliary alloc_mdl_locks() function for allocating metadata
lock requests objects for all elements of table list. Added
auxiliary set_all_mdl_upgradable() function for marking all
elements in table list as requiring upgradable metadata locks.
storage/myisammrg/ha_myisammrg.cc:
Allocate MDL_LOCK objects for underlying tables of MERGE table.
To be reworked once Ingo pushes his patch for WL4144.
