------------------------------------------------------------
revno: 2617.68.24
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg-pre2-2
timestamp: Wed 2009-09-16 17:25:29 +0400
message:
  Pre-requisite patch for fixing bug #30977 "Concurrent statement
  using stored function and DROP FUNCTION breaks SBR".

  Added MDL_request for stored routine as member to Sroutine_hash_entry
  in order to be able perform metadata locking for stored routines in
  future (Sroutine_hash_entry is an equivalent of TABLE_LIST class for
  stored routines).
(WL#4284, follow up fixes).

sql/mdl.cc:
  Introduced version of MDL_request::init() method which initializes
  lock request using pre-built MDL key.
  MDL_key::table_name/table_name_length() getters were
  renamed to reflect the fact that MDL_key objects are
  now created not only for tables.
sql/mdl.h:
  Extended enum_mdl_namespace enum with values which correspond
  to namespaces for stored functions and triggers.
  Renamed MDL_key::table_name/table_name_length() getters
  to MDL_key::name() and name_length() correspondingly to
  reflect the fact that MDL_key objects are now created
  not only for tables.
  Added MDL_key::mdl_namespace() getter.
  Also added version of MDL_request::init() method which
  initializes lock request using pre-built MDL key.
sql/sp.cc:
  Added MDL_request for stored routine as member to Sroutine_hash_entry.
  Changed code to use MDL_key from this request as a key for LEX::sroutines
  set. Removed separate "key" member from Sroutine_hash_entry as it became
  unnecessary.
sql/sp.h:
  Added MDL_request for stored routine as member to Sroutine_hash_entry
  in order to be able perform metadata locking for stored routines in
  future (Sroutine_hash_entry is an equivalent of TABLE_LIST class for
  stored routines).
  Removed Sroutine_hash_entry::key member as now we can use MDL_key from
  this request as a key for LEX::sroutines set.
sql/sp_head.cc:
  Removed sp_name::m_sroutines_key member and set_routine_type() method.
  Since key for routine in LEX::sroutines set has no longer sp_name::m_qname
  as suffix we won't save anything by creating it at sp_name construction
  time.
  Adjusted sp_name constructor used for creating temporary objects for
  lookups in SP-cache to accept MDL_key as parameter and to avoid any
  memory allocation.
  Finally, removed sp_head::m_soutines_key member for reasons similar
  to why sp_name::m_sroutines_key was removed
sql/sp_head.h:
  Removed sp_name::m_sroutines_key member and set_routine_type() method.
  Since key for routine in LEX::sroutines set has no longer sp_name::m_qname
  as suffix we won't save anything by creating it at sp_name construction
  time.
  Adjusted sp_name constructor used for creating temporary objects for
  lookups in SP-cache to accept MDL_key as parameter and to avoid any
  memory allocation.
  Finally, removed sp_head::m_soutines_key member for reasons similar
  to why sp_name::m_sroutines_key was removed.
sql/sql_base.cc:
  Adjusted code to the fact that we now use MDL_key from
  Sroutine_hash_entry::mdl_request as a key for LEX::sroutines set.
  MDL_key::table_name/table_name_length() getters were
  renamed to reflect the fact that MDL_key objects are
  now created not only for tables.
sql/sql_trigger.cc:
  sp_add_used_routine() now takes MDL_key as parameter as now we use
  instance of this class as a key for LEX::sroutines set.

revno: 2617.68.23
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg-pre1
timestamp: Wed 2009-09-16 09:34:42 +0400
message:
  Pre-requisite patch for fixing bug #30977 "Concurrent statement
  using stored function and DROP FUNCTION breaks SBR".

  CREATE TABLE SELECT statements take exclusive metadata lock on table
  being created. Invariant of metadata locking subsystem states that
  such lock should be taken before taking any kind of shared locks.
  Once metadata locks on stored routines are introduced statements like
  "CREATE TABLE ... SELECT f1()" will break this invariant by taking
  shared locks on routines before exclusive lock on target table.
  To avoid this, open_tables() is reworked to process tables which are
  directly used by the statement before stored routines are processed.

sql/sql_base.cc:
  Refactored open_tables() implementation to process stored routines 
  only after tables which are directly used by statement were processed.
            
  To achieve this moved handling of routines in open_tables() out of 
  loop which iterates over tables to a new separate loop. And in its 
  turn this allowed to split handling of particular table or view to 
  an auxiliary function, which made code in open_tables() simpler and 
  more easy to understand.

------------------------------------------------------------
revno: 2617.68.10
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg46673
timestamp: Tue 2009-09-01 19:57:05 +0400
message:
  Fix for bug #46673 "Deadlock between FLUSH TABLES WITH READ LOCK and DML".

  Deadlocks occured when one concurrently executed transactions with
  several statements modifying data and FLUSH TABLES WITH READ LOCK
  statement or SET READ_ONLY=1 statement.

  These deadlocks were introduced by the patch for WL 4284: "Transactional
  DDL locking"/Bug 989: "If DROP TABLE while there's an active transaction,
  wrong binlog order" which has changed FLUSH TABLES WITH READ LOCK/SET
  READ_ONLY=1 to wait for pending transactions.
  What happened was that FLUSH TABLES WITH READ LOCK blocked all further
  statements changing tables by setting global_read_lock global variable
  and has started waiting for all pending transactions to complete.
  Then one of those transactions tried to executed DML, detected that
  global_read_lock non-zero and tried to wait until global read lock will
  be released (i.e. global_read_lock becomes 0), indeed, this led to a
  deadlock.

  Proper solution for this problem should probably involve full integration
  of global read lock with metadata locking subsystem (which will allow to
  implement waiting for pending transactions without blocking DML in them).
  But since it requires significant changes another, short-term solution
  for the problem is implemented in this patch.

  Basically, this patch restores behavior of FLUSH TABLES WITH READ LOCK/
  SET READ_ONLY=1 before the patch for WL 4284/bug 989. By ensuring that
  extra references to TABLE_SHARE are not stored for active metadata locks
  it changes these statements not to wait for pending transactions.
  As result deadlock is eliminated.
  Note that this does not change the fact that active FLUSH TABLES WITH
  READ LOCK lock or SET READ_ONLY=1 prevent modifications to tables as
  they also block transaction commits.


mysql-test/r/flush_block_commit.result:
  Adjusted test case after change in FLUSH TABLES WITH READ LOCK behavior
  - it is no longer blocked by a pending transaction.
mysql-test/r/mdl_sync.result:
  Added test for bug #46673 "Deadlock between FLUSH TABLES WITH READ LOCK
  and DML".
mysql-test/r/read_only_innodb.result:
  Adjusted test case after change in SET READ_ONLY behavior - it is no
  longer blocked by a pending transaction.
mysql-test/t/flush_block_commit.test:
  Adjusted test case after change in FLUSH TABLES WITH READ LOCK behavior
  - it is no longer blocked by a pending transaction.
mysql-test/t/mdl_sync.test:
  Added test for bug #46673 "Deadlock between FLUSH TABLES WITH READ LOCK
  and DML".
mysql-test/t/read_only_innodb.test:
  Adjusted test case after change in SET READ_ONLY behavior - it is no
  longer blocked by a pending transaction.
sql/sql_base.cc:
  Disable caching of pointers to TABLE_SHARE objects in MDL subsystem.
  This means that transactions holding metadata lock on the table will
  no longer have extra reference to the TABLE_SHARE (due to this lock)
  and will no longer block concurrent FLUSH TABLES/FLUSH TABLES WITH
  READ LOCK. Note that this does not change the fact that FLUSH TABLES
  WITH READ LOCK prevents concurrent transactions from modifying data
  as it also blocks all commits.

------------------------------------------------------------
revno: 2617.68.7
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg46044
timestamp: Thu 2009-08-27 10:22:17 +0400
message:
  Fix for bug #46044 "MDL deadlock on LOCK TABLE + CREATE TABLE HIGH_PRIORITY
  FOR UPDATE".

  Deadlock occured when during execution of query to I_S we tried to open
  a table or its .FRM in order to get information about it and had to wait
  because we have encountered exclusive metadata lock on this table held by
  a DDL operation from another connection which in its turn waited for some
  resource currently owned by connection executing this I_S query.
  For example, this might have happened if one under LOCK TABLES executed I_S
  query targeted to particular table (which was not among locked) and also
  concurrently tried to create this table using CREATE TABLE SELECT which
  had to wait for one of tables locked by the first connection.
  Another situation in which deadlock might have occured is when I_S query,
  which was executed as part of transaction, tried to get information about
  table which just has been dropped by concurrent DROP TABLES executed under
  LOCK TABLES and this DROP TABLES for its completion also had to wait
  transaction from the first connection.

  This problem stemmed from the fact that opening of tables/.FRMs for I_S
  filling is happening outside of connection's main MDL_context so code
  which tries to detect deadlocks due to conflicting metadata locks doesn't
  work in this case. Indeed, this led to deadlocks when during I_S filling
  we tried to wait for conflicting metadata lock to go away, while its owner
  was waiting for some resource held by connection executing I_S query.

  This patch solves this problem by avoiding waiting in such situation.
  Instead we skip this table and produce warning that information about
  it was omitted from I_S due to concurrent DDL operation. We still wait
  for conflicting metadata lock to go away when it is known that deadlock
  is not possible (i.e. when connection executing I_S query does not hold
  any metadata or table-level locks).
  Basically, we apply our standard deadlock avoidance technique for metadata
  locks to the process of filling of I_S tables but replace ER_LOCK_DEADLOCK
  error with a warning.
  Note that this change is supposed to be safe for 'mysqldump' since the
  only its mode which is affected by this change is --single-transaction mode
  is not safe in the presence of concurrent DDL anyway (and this fact is
  documented). Other modes are unaffected because they either use
  SHOW TABLES/SELECT * FROM I_S.TABLE_NAMES which do not take any metadata
  locks in the process of I_S table filling and thus cannot skip tables or
  execute I_S queries for tables which were previously locked by LOCK TABLES
  (or in the presence of global read lock) which excludes possibility of
  encountering conflicting metadata lock.


mysql-test/r/mdl_sync.result:
  Added test for bug #46044 "MDL deadlock on LOCK TABLE + CREATE TABLE
  HIGH_PRIORITY FOR UPDATE".
mysql-test/t/mdl_sync.test:
  Added test for bug #46044 "MDL deadlock on LOCK TABLE + CREATE TABLE
  HIGH_PRIORITY FOR UPDATE".
sql/mysql_priv.h:
  Added a new flag for open_table() call which allows it to fail
  with an error in cases when conflicting metadata lock is discovered
  instead of waiting until this lock goes away.
sql/share/errmsg-utf8.txt:
  Added error/warning message to be generated in cases when information
  about table is omitted from I_S since there is conflicting metadata lock
  on the table.
sql/share/errmsg.txt:
  Added error/warning message to be generated in cases when information
  about table is omitted from I_S since there is conflicting metadata lock
  on the table.
sql/sql_base.cc:
  Added a new flag for open_table() call which allows it to fail
  with an error in cases when conflicting metadata lock is discovered
  instead of waiting until this lock goes away.
sql/sql_show.cc:
  When we are opening a table (or just .FRM) in order to fill I_S with
  information about this table and encounter conflicting metadata lock
  waiting for this lock to go away can lead to a deadlock in some
  situations (under LOCK TABLES, within transaction, etc.). To avoid
  these deadlocks we detect such situations and don't do waiting.
  Instead, we skip table for which we have conflicting metadata lock,
  thus omitting information about it from I_S table, and produce an
  appropriate warning.

------------------------------------------------------------
revno: 2617.69.37
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg46748
timestamp: Fri 2009-08-21 18:17:02 +0400
message:
  Fix for bug #46748 "Assertion in MDL_context::wait_for_locks()
  on INSERT + CREATE TRIGGER".

  Concurrent execution of statements involving stored functions or triggers
  which were using several tables and DDL statements which affected those
  tables on debug build of server might have led to assertion failures in
  MDL_context::wait_for_locks(). Non-debug build was not affected.

  The problem was that during back-off which happens when open_tables()
  encounters conflicting metadata lock for one of the tables being open
  we didn't reset MDL_request::ticket value for requests which correspond
  to tables from extended prelocking set. Since these requests are part
  of of list of requests to be waited for in Open_table_context this broke
  assumption that ticket value for them is 0 in MDL_context::wait_for_locks()
  and caused assertion failure.

  This fix ensures that close_tables_for_reopen(), which performs this back-off
  resets MDL_request::ticket value not only for tables directly used by the
  statement but also for tables from extended prelocking set, thus satisfying
  assumption described above.



mysql-test/r/mdl_sync.result:
  Added test case for bug #46748 "Assertion in MDL_context::wait_for_locks()
  on INSERT + CREATE TRIGGER".
mysql-test/t/mdl_sync.test:
  Added test case for bug #46748 "Assertion in MDL_context::wait_for_locks()
  on INSERT + CREATE TRIGGER".
sql/sql_base.cc:
  Since metadata lock requests for tables from extended part of prelocking
  set are also part of list of requests to be waited for in Open_table_context
  in close_tables_for_reopen() we have to reset MDL_request::ticket 
  values for them to assumptions in MDL_context::wait_for_locks().

Bug #47249 assert in MDL_global_lock::is_lock_type_compatible

This assert could be triggered if LOCK TABLES were used to lock
both a table and a view that used the same table. The table would have
to be first WRITE locked and then READ locked. So "LOCK TABLES v1
WRITE, t1 READ" would eventually trigger the assert, "LOCK TABLES
v1 READ, t1 WRITE" would not. The reason is that the ordering of locks
in the interal representation made a difference when executing 
FLUSH TABLE on the table.

During FLUSH TABLE, a lock was upgraded to exclusive. If this lock
was of type MDL_SHARED and not MDL_SHARED_UPGRADABLE, an internal
counter in the MDL subsystem would get out of sync. This would happen
if the *last* mention of the table in LOCK TABLES was a READ lock.

The counter in question is the number exclusive locks (active or intention). 
This is used to make sure a global metadata lock is only taken when the 
counter is zero (= no conflicts). The counter is increased when a
MDL_EXCLUSIVE or MDL_SHARED_UPGRADABLE lock is taken, but not when 
upgrade_shared_lock_to_exclusive() is used to upgrade directly
from MDL_SHARED to MDL_EXCLUSIVE. 

This patch fixes the problem by searching for a TABLE instance locked
with MDL_SHARED_UPGRADABLE or MDL_EXCLUSIVE before calling
upgrade_shared_lock_to_exclusive(). The patch also adds an assert checking
that only MDL_SHARED_UPGRADABLE locks are upgraded to exclusive.

Test case added to lock_multi.test.

------------------------------------------------------------
revno: 2617.69.32
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg46747
timestamp: Wed 2009-08-19 18:12:27 +0400
message:
  Fix for bug #46747 "Crash in MDL_ticket::upgrade_shared_lock_to_exclusive
  on TRIGGER + TEMP table".

  Server crashed when one tried to drop trigger which had its subject
  table shadowed by a temporary table with the same name.

  This problem occured because in such situation DROP TRIGGER has opened
  temporary table instead of base table on which trigger was defined.
  Attempt to upgrade metadata lock on this temporary table led to crash
  (we don't acquire metadata locks for temporary tables).

  This fix ensures that DROP TRIGGER ignores temporary tables when
  trying to open table on which trigger to be dropped is defined.


mysql-test/r/trigger.result:
  Added test case for bug #46747 "Crash in
  MDL_ticket::upgrade_shared_lock_to_exclusive
  on TRIGGER + TEMP table".
mysql-test/t/trigger.test:
  Added test case for bug #46747 "Crash in
  MDL_ticket::upgrade_shared_lock_to_exclusive
  on TRIGGER + TEMP table".
sql/sql_trigger.cc:
  Prevent DROP TRIGGER from opening temporary table which might
  shadow base table on which trigger to be dropped is defined.

revno: 2617.69.33
committer: Konstantin Osipov <kostja@sun.com>
branch nick: mysql-next-46452
timestamp: Wed 2009-08-19 18:39:31 +0400
message:
  Bug#46452 "Crash in MDL, HANDLER OPEN + TRUNCATE TABLE".
  Flush open HANDLER tables before TRUNCATE, which is a DDL.


mysql-test/r/truncate.result:
  Update results for Bug#46452.
mysql-test/t/truncate.test:
  Add a test case for Bug#46452 "Crash in MDL, HANDLER OPEN + TRUNCATE TABLE".

----------------------------------------------------------
revno: 2617.69.28
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-azalea-bugfixing
timestamp: Tue 2009-08-18 15:27:35 +0400
message:
  An attempt to fix a link failure on Windows -- Sroutine_hash_entry
  is forward-declared as class.
(Part of WL#4284).

----------------------------------------------------------
revno: 2617.69.25
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-42546
timestamp: Fri 2009-08-14 23:52:00 +0400
message:
  A cleanup in open_tables() and lock_tables():
  change return type of these functions to bool from int,
  to follow convention in the rest of the code.
(Part of WL#4284 review fixes).

sql/mysql_priv.h:
  Change return type of open_talbes() and lock_tables() from
  int to bool.
sql/sql_base.cc:
  Change return type of open_tables() and lock_tables() from int to bool.
sql/sql_handler.cc:
  Use bool now that open_tables() returns bool.

A pre-requisite patch for Bug#30977 "Concurrent statement using 
stored function and DROP FUNCTION breaks SBR".

This patch changes the MDL API by introducing a namespace for
lock keys: MDL_TABLE for tables and views and MDL_PROCEDURE
for stored procedures and functions. The latter is needed for
the fix for Bug#30977.

Bug #42074 concurrent optimize table and 
           alter table = Assertion failed: thd->is_error()

This assertion could occur if OPTIMIZE TABLE was started on a InnoDB table
and the table was altered to different storage engine after OPTIMIZE
had started. This allowed OPTIMIZE to pass the initial checks for 
storage engine support, but fail once it reached "recreate+analyze"
if this operation was not supported by the new storage engine.
The bug had no consequences for non-debug builds of the server.

In detail, the assertion was triggered when ha_analyze() returned 
HA_ADMIN_NOT_IMPLEMENTED. This led to a code path which included an 
assert checking for diagnostics area contents. Since this area had 
not been filled, the assertion was triggered. The diagnostics area 
is in this case only used to provide more detailed information about 
why optimize failed. The triggered code path sends this information 
to the client and clears the diagnostic area.

This patch fixed the problem by adding an error message to the diagnostic 
area if ha_analyze() fails. This error message contains the error code
returned by ha_analyze().

Test case added to innodb_mysql_sync.test.

Bug #43272 HANDLER SQL command does not work under LOCK TABLES

HANDLER commands are now explicitly disallowed in LOCK TABLES mode.

Before, HANDLER OPEN gave the misleading error message: "Table x was 
not locked with LOCK TABLES". This patch changes HANDLER OPEN/READ/CLOSE 
to give ER_LOCK_OR_ACTIVE_TRANSACTION "Can't execute the given command 
because you have active locked tables or an active transaction" in
LOCK TABLES mode.

Test case added to lock.test.

Bug #45067 Assertion `stmt_da->is_error()' in 
           Delayed_insert::open_and_lock_table

The assert was triggered when delayed insert was killed by another 
connection using mysql_notify_thread_having_shared_lock().
During handling of thd->killed, thd.fatal_error() was called without
a previous call to my_error() which triggered the assert.
This patch allows the assert to pass if thd->killed has been set.

----------------------------------------------------------
revno: 2617.69.24
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-42546
timestamp: Fri 2009-08-14 19:22:05 +0400
message:
  A pre-requisite for a fix for Bug#42546 "Backup: RESTORE fails, thinking it
  finds an existing table"
  Back-port from WL 148 "Foreign keys" feature tree a patch
  that introduced Prelocking_strategy class -- a way to parameterize
  open_tables() behaviour, implemented by Dmitry Lenev.

(Part of WL#4284).

sql/sql_base.cc:
  Implement different prelocking strategies. Use an instance of
  prelocking_strategy in open_tables().
sql/sql_class.h:
  Add declarations for class Prelocking_strategy.
sql/sql_lex.h:
  Add a helper method to access last table of the global table list
  (lex->query_tables).
sql/sql_parse.cc:
  Use a special prelocking strategy when locking tables for LOCK TABLES.
sql/sql_table.cc:
  Use normal open_and_lock_tables_derived() in ALTER TABLE.
sql/sql_yacc.yy:
  Modify the grammar to not pollute the global table list with tables
  that should not be opened.

----------------------------------------------------------
revno: 2617.69.21
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-4284-1-assert
timestamp: Thu 2009-08-13 20:13:55 +0400
message:
  A fix and a test case for Bug#46610 "MySQL 5.4.4: MyISAM MRG engine crash
  on auto-repair of child".
  Also fixes Bug#42862 "Crash on failed attempt to open a children of a
  merge table".

  MERGE engine needs to extend the global table list
  with TABLE_LIST elements for child tables,
  so that they are opened and locked.
  Previously these table list elements were allocated
  in memory of ha_myisammrg object (MERGE engine handler).
  That would lead to access to freed memory in
  recover_from_failed_open_table_attempt(), which would
  try to recover a MERGE table child (MyISAM table)
  and use for that TABLE_LIST of that child.
  But by the time recover_from_failed_open_table_attempt()
  is invoked, ha_myisammrg object that owns this
  TABLE_LIST may be destroyed, and thus TABLE_LIST
  memory freed.

  The fix is to ensure that TABLE_LIST elements
  that are added to the global table list (lex->query_tables)
  are always allocated in thd->mem_root, which is not
  destroyed until end of execution.

  If previously TABLE_LIST elements were allocated
  at ha_myisammrg::open() (i.e. when the TABLE
  object was created and added to the table cache),
  now they are allocated in ha_myisammrg::add_chidlren_list()
  (i.e. right after "open" of the merge parent in
  open_tables()).
  We still create a list of children names
  at ha_myisammrg::open() to use as a basis
  for creation of TABLE_LISTs, that allows
  to avoid reading the merge handler data
  file on every execution.


mysql-test/r/merge_recover.result:
  Test results for Bug#46610.
mysql-test/t/merge_recover-master.opt:
  Option file for Bug#46610 test (need a new test because
  of that option, which is not tested anywhere else).
mysql-test/t/merge_recover.test:
  Add a test case for Bug#46610.
sql/table.h:
  MERGE child child_def_version is now moved from TABLE_LIST
  to MERGE engine specific data structure.
storage/myisammrg/ha_myisammrg.cc:
  Introduce an auxiliary structure to keep MERGE child name
  and definition version. A list of Mrg_child_def is created
  in ha_myisammrg::open() and reused in ha_myisammrg::add_children_list().

Bug #22876 Four-way deadlock

This bug was fixed as a part of Bug#989 
"If DROP TABLE while there's an active transaction, wrong binlog order"
A statement which would have caused circular wait will now 
be aborted with ER_LOCK_DEADLOCK.

Test case based on bug description added to innodb_mysql_lock.test.
Note that innodb_lock_wait_timeout is set to 5 mins to 
prevent race conditions in the test.

Bug #39675 rename tables on innodb tables with pending 
           transactions causes slave data issue

Bug was already fixed as part of patch for Bug#989 
(If DROP TABLE while there's an active transaction, 
wrong binlog order) 

Test case added to rpl_innodb.test.

Bug #45066 FLUSH TABLES WITH READ LOCK deadlocks against LOCK TABLE

Test coverage for combinations of LOCK TABLE READ / WRITE and 
FLUSH TABLES / FLUSH TABLES WITH READ LOCK added to lock.test.
LOCK and FLUSH are executed sequentially from one connection.

----------------------------------------------------------
revno: 2617.69.20
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-4284-1-assert
timestamp: Thu 2009-08-13 18:29:55 +0400
message:
  WL#4284 "Transactional DDL locking"
  A review fix.
  Since WL#4284 implementation separated MDL_request and MDL_ticket,
  MDL_request becamse a utility object necessary only to get a ticket.
  Store it by-value in TABLE_LIST with the intent to merge
  MDL_request::key with table_list->table_name and table_list->db
  in future.
  Change the MDL subsystem to not require MDL_requests to
  stay around till close_thread_tables().
  Remove the list of requests from the MDL context.
  Requests for shared metadata locks acquired in open_tables()
  are only used as a list in recover_from_failed_open_table_attempt(),
  which calls mdl_context.wait_for_locks() for this list.
  To keep such list for recover_from_failed_open_table_attempt(),
  introduce a context class (Open_table_context), that collects
  all requests.
  A lot of minor cleanups and simplications that became possible
  with this change.


sql/event_db_repository.cc:
  Remove alloc_mdl_requests(). Now MDL_request instance is a member
  of TABLE_LIST, and init_one_table() initializes it.
sql/ha_ndbcluster_binlog.cc:
  Remove now unnecessary declaration and initialization
  of binlog_mdl_request.
sql/lock.cc:
  No need to allocate MDL requests in lock_table_names() now.
sql/log.cc:
  Use init_one_table() method, remove alloc_mdl_requests(),
  which is now unnecessary.
sql/log_event.cc:
  No need to allocate mdl_request separately now.
  Use init_one_table() method.
sql/log_event_old.cc:
  Update to the new signature of close_tables_for_reopen().
sql/mdl.cc:
  Update try_acquire_exclusive_lock() to be more easy to use.
  Function lock_table_name_if_not_cached() has been removed.
  Make acquire_shared_lock() signature consistent with
  try_acquire_exclusive_lock() signature.
  Remove methods that are no longer used.
  Update comments.
sql/mdl.h:
  Implement an assignment operator that doesn't
  copy MDL_key (MDL_key::operator= is private and
  should remain private).
  This is a hack to work-around assignment of TABLE_LIST
  by value in several places. Such assignments violate
  encapsulation, since only perform a shallow copy.
  In most cases these assignments are a hack on their own.
sql/mysql_priv.h:
  Update signatures of close_thread_tables() and close_tables_for_reopen().
sql/sp.cc:
  Allocate TABLE_LIST in thd->mem_root.
  Use init_one_table().
sql/sp_head.cc:
  Use init_one_table().
  Remove thd->locked_tables_root, it's no longer needed.
sql/sql_acl.cc:
  Use init_mdl_requests() and init_one_table().
sql/sql_base.cc:
  Update to new signatures of try_acquire_shared_lock() and
  try_acquire_exclusive_lock().
  Remove lock_table_name_if_not_cached().
  Fix a bug in open_ltable() that would not return ER_LOCK_DEADLOCK
  in case of a failed lock_tables() and a multi-statement
  transaction.
  Fix a bug in open_and_lock_tables_derived() that would
  not return ER_LOCK_DEADLOCK in case of a multi-statement
  transaction and a failure of lock_tables().
  Move assignment of enum_open_table_action to a method of Open_table_context, a new class that maintains information
  for backoff actions.
  Minor rearrangements of the code.
  Remove alloc_mdl_requests() in functions that work with system
  tables: instead the patch ensures that callers always initialize
  TABLE_LIST argument.
sql/sql_class.cc:
  THD::locked_tables_root is no more.
sql/sql_class.h:
  THD::locked_tables_root is no more.
  Add a declaration for Open_table_context class.
sql/sql_delete.cc:
  Update to use the simplified MDL API.
sql/sql_handler.cc:
  TABLE_LIST::mdl_request is stored by-value now.
  Ensure that mdl_request.ticket is NULL for every request
  that is passed into MDL, to satisfy MDL asserts.
  @ sql/sql_help.cc
  Function open_system_tables_for_read() no longer initializes
  mdl_requests.
  Move TABLE_LIST::mdl_request initialization closer to
  TABLE_LIST initialization.
sql/sql_help.cc:
  Function open_system_tables_for_read() no longer initializes
  mdl_requests.
  Move TABLE_LIST::mdl_request initialization closer to
  TABLE_LIST initialization.
sql/sql_insert.cc:
  Remove assignment by-value of TABLE_LIST in
  TABLEOP_HOOKS. We can't carry over a granted
  MDL ticket from one table list to another.
sql/sql_parse.cc:
  Change alloc_mdl_requests() -> init_mdl_requests().
  @todo We can remove init_mdl_requests() altogether
  in some places: all places that call add_table_to_list()
  already have mdl requests initialized.
sql/sql_plugin.cc:
  Use init_one_table().
  THD::locked_tables_root is no more.
sql/sql_servers.cc:
  Use init_one_table().
sql/sql_show.cc:
  Update acquire_high_priority_shared_lock() to use
  TABLE_LIST::mdl_request rather than allocate an own.
  Fix get_trigger_table_impl() to use init_one_table(),
  check for out of memory, follow the coding style.
sql/sql_table.cc:
  Update to work with TABLE_LIST::mdl_request by-value.
  Remove lock_table_name_if_not_cached().
  The code that used to delegate to it is quite simple and
  concise without it now.
sql/sql_udf.cc:
  Use init_one_table().
sql/sql_update.cc:
  Update to use the new signature of close_tables_for_reopen().
sql/table.cc:
  Move re-setting of mdl_requests for prepared statements
  and stored procedures from close_thread_tables() to
  reinit_stmt_before_use().
  Change alloc_mdl_requests() to init_mdl_requests().
  init_mdl_requests() is a hack that can't be deleted
  until we don't have a list-aware TABLE_LIST constructor.
  Hopefully its use will be minimal
sql/table.h:
  Change alloc_mdl_requests() to init_mdl_requests()
  TABLE_LIST::mdl_request is stored by value.
sql/tztime.cc:
  We no longer initialize mdl requests in open_system_tables_for*()
  functions. Move this initialization closer to initialization
  of the rest of TABLE_LIST members.
storage/myisammrg/ha_myisammrg.cc:
  Simplify mdl_request initialization.

----------------------------------------------------------
revno: 2617.69.2
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-azalea-bugfixing
timestamp: Mon 2009-08-03 19:26:04 +0400
message:
  A fix and a test case for Bug#45035 "Altering table under LOCK TABLES
  results in "Error 1213 Deadlock found...".

  If a user had a table locked with LOCK TABLES
  for READ and for WRITE in the same connection, ALTER TABLE
  could fail.

  Root cause analysis:

  If a connection issues

  LOCK TABLE t1 write, t1 a read, t1 b read;

  the new LOCK TABLES code in 6.0 (part of WL 3726) will create
  the following list of TABLE_LIST objects
  (thd->locked_tables_list->m_locked_tables):

  {"t1" "b" tl_read_no_insert}, {"t1" "a" tl_read_no_insert},
  {"t1" "t1" tl_write }

  Later on, when we try to ALTER table t1, mysql_alter_table()
  closes all TABLE instances and releases its thr_lock locks,
  keeping only an exclusive metadata lock on t1.

  But when ALTER is finished, Locked_table_list::reopen_tables()
  tries to restore the original list of open and locked tables.

  Before this patch, it used to do so one by one:
  Open t1 b, get TL_READ_NO_INSERT lock,
  Open t1 a, get TL_READ_NO_INSERT lock
  Open t1, try to get TL_WRITE lock, deadlock.

  The cause of the deadlock is that thr_lock.c doesn't
  resolve the situation when the read list only consists
  of locks taken by the same thread, followed by this very
  thread trying to take a WRITE lock. Indeed, since
  thr_lock_multi always gets a sorted list of locks,
  WRITE locks always precede READ locks in the list
  to lock.

  Don't try to fix thr_lock.c deficiency, keep this
  code simple.
  Instead, try to take all thr_lock locks at once
  in ::reopen_tables().


mysql-test/r/lock.result:
  Update results: test case for Bug#45035.
mysql-test/t/lock.test:
  Add a test case for Bug#45035.
sql/sql_base.cc:
  Take all thr_lock locks at once in Locked_tables_list::reopen_tables().
sql/sql_class.h:
  Add a helper array to store tables for mysql_lock_tables()
  in reopen_tables().
sql/sql_table.cc:
  Update unlink_all_closed_tables() to the new signature.

------------------------------------------------------------
revno: 2617.65.6
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-azalea-bg39674
timestamp: Sat 2009-07-25 00:28:43 +0400
message:
  Fix for bug #39674 "On shutdown mdl_destroy() called before
  plugin_shutdown()".

  Attempt to shutdown PBXT engine plugin led to assertion failure
  caused by using already destroyed mutex in metadata locking
  subsystem.

  This problem stemmed from the fact that we MDL subsystem and
  table definition cache were deinitialized before plugin shutdown
  while PBXT plugin during its shutdown process accessed tables and
  therefore expected them to be in working shape.

  This patch solves this problem by moving deinitialization of
  these two subsystems after plugins are shut down.

  No test case is provided since such test case would require
  using PBXT or other plugin which accesses tables during its
  shutdown process.


sql/mysql_priv.h:
  Introduced table_def_start_shutdown() function which informs
  table definition cache that shutdown process has been started
  so it has to keep number of TABLE and TABLE_SHARE objects minimal
  in order to reduce number of references to pluggable engines.
sql/mysqld.cc:
  Destroy table definition cache and meta-data locking subsystem
  after shutting down plugins. This allows plugins to work with
  tables during their shutdown.
  Since table definition cache hold references to storage engine
  plugins we have to remove unused tables from it before shutting
  down plugins and keep number of these references minimal during
  the process (by immediately removing tables opened during this
  process from the table definition cache).
sql/sql_base.cc:
  Introduced table_def_start_shutdown() function which informs
  table definition cache that shutdown process has been started
  so it has to keep number of TABLE and TABLE_SHARE objects
  minimal in order to reduce number of references to pluggable
  engines.
          This allows to smoothly shutdown such plugins without completely
          prohibiting access to tables/table definition cache while
          shutting down other plugins.

------------------------------------------------------------
revno: 2617.43.3
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 40188-6.0
timestamp: Thu 2009-05-07 13:15:54 +0200
message:
Sort results as the file list of the database directory is not
sorted (MY_DONT_SORT).

(This is a follow-up fix for WL#4284).

mysql-test/r/drop_debug.result:
  Update test case result.
mysql-test/t/drop_debug.test:
  Sort warnings.

------------------------------------------------------------
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: 2617.23.22
committer: Konstantin Osipov <kostja@sun.com>
branch nick: mysql-6.0-runtime
timestamp: Wed 2009-03-04 23:29:16 +0300
message:
  WL#4284, "Transactional DDL locking": fix a Windows compilation warning.

------------------------------------------------------------
revno: 2617.23.23
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: mysql-6.0-runtime
timestamp: Thu 2009-03-05 18:39:58 -0300
message:
Fix for broken build: SHARED is defined by Solaris headers.


sql/mdl.cc:
  Add MDL_LOCK prefix to the lock types of MDL_LOCK.

----------------------------------------------------------
revno: 2617.23.20
committer: Konstantin Osipov <kostja@sun.com>
branch nick: mysql-6.0-runtime
timestamp: Wed 2009-03-04 16:31:31 +0300
message:
  WL#4284 "Transactional DDL locking"
  Review comments: "Objectify" the MDL API.
  MDL_request and MDL_context still need manual construction and
  destruction, since they are used in environment that is averse
  to constructors/destructors.


sql/mdl.cc:
  Improve comments.
  Add asserts to backup()/restore_from_backup()/merge() methods.
  Fix an order bug in the error path of mdl_acquire_exclusive_locks():
  we used to first free a ticket object, and only then exclude
  it from the list of tickets.

----------------------------------------------------------
revno: 2617.23.19
committer: Konstantin Osipov <kostja@sun.com>
branch nick: mysql-6.0-runtime
timestamp: Tue 2009-03-03 01:20:44 +0300
message:
  Metadata locking: realign comments. No semantical changes,
  only enforce a bit of the coding style.
This is a review fix for WL#4284 "Transactional DDL locking".

sql/mdl.cc:
  Realign doxygen comments.
sql/mdl.h:
  Realign doxygen comments.

------------------------------------------------------------
revno: 2617.23.18
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 4284-6.0
timestamp: Mon 2009-03-02 18:18:26 -0300
message:
Bug#989: If DROP TABLE while there's an active transaction, wrong binlog order
WL#4284: Transactional DDL locking

This is a prerequisite patch:

These changes are intended to split lock requests from granted
locks and to allow the memory and lifetime of granted locks to
be managed within the MDL subsystem. Furthermore, tickets can
now be shared and therefore are used to satisfy multiple lock
requests, but only shared locks can be recursive.

The problem is that the MDL subsystem morphs lock requests into
granted locks locks but does not manage the memory and lifetime
of lock requests, and hence, does not manage the memory of
granted locks either. This can be problematic because it puts the
burden of tracking references on the users of the subsystem and
it can't be easily done in transactional contexts where the locks
have to be kept around for the duration of a transaction.

Another issue is that recursive locks (when the context trying to
acquire a lock already holds a lock on the same object) requires
that each time the lock is granted, a unique lock request/granted
lock structure structure must be kept around until the lock is
released. This can lead to memory leaks in transactional contexts
as locks taken during the transaction should only be released at
the end of the transaction. This also leads to unnecessary wake
ups (broadcasts) in the MDL subsystem if the context still holds
a equivalent of the lock being released.

These issues are exacerbated due to the fact that WL#4284 low-level
design says that the implementation should "2) Store metadata locks
in transaction memory root, rather than statement memory root" but
this is not possible because a memory root, as implemented in mysys,
requires all objects allocated from it to be freed all at once.

This patch combines review input and significant code contributions
from Konstantin Osipov (kostja) and Dmitri Lenev (dlenev).


mysql-test/r/mdl_sync.result:
  Add test case result.
mysql-test/t/mdl_sync.test:
  Add test case for shared lock upgrade case.
sql/event_db_repository.cc:
  Rename mdl_alloc_lock to mdl_request_alloc.
sql/ha_ndbcluster_binlog.cc:
  Use new function names to initialize MDL lock requests.
sql/lock.cc:
  Rename MDL functions.
sql/log_event.cc:
  The MDL request now holds the table and database name data (MDL_KEY).
sql/mdl.cc:
  Move the MDL key to the MDL_LOCK structure in order to make the
  object suitable for allocation from a fixed-size allocator. This
  allows the simplification of the lists in the MDL_LOCK object,
  which now are just two, one for granted tickets and other for
  waiting (upgraders) tickets.
  
  Recursive requests for a shared lock on the same object can now
  be granted using the same lock ticket. This schema is only used
  for shared locks because that the only case that matters. This
  is used to avoid waste of resources in case a context (connection)
  already holds a shared lock on a object.
sql/mdl.h:
  Introduce a metadata lock object key which is used  to uniquely
  identify lock objects.
  
  Separate the structure used to represent pending lock requests
  from the structure used to represent granted metadata locks.
  
  Rename functions used to manipulate locks requests in order to
  have a more consistent function naming schema.
sql/sp_head.cc:
  Rename mdl_alloc_lock to mdl_request_alloc.
sql/sql_acl.cc:
  Rename alloc_mdl_locks to alloc_mdl_requests.
sql/sql_base.cc:
  Various changes to accommodate that lock requests are separated
  from lock tickets (granted locks).
sql/sql_class.h:
  Last acquired lock before the savepoint was set.
sql/sql_delete.cc:
  Various changes to accommodate that lock requests are separated
  from lock tickets (granted locks).
sql/sql_handler.cc:
  Various changes to accommodate that lock requests are separated
  from lock tickets (granted locks).
sql/sql_insert.cc:
  Rename alloc_mdl_locks to alloc_mdl_requests.
sql/sql_parse.cc:
  Rename alloc_mdl_locks to alloc_mdl_requests.
sql/sql_plist.h:
  Typedef for iterator type.
sql/sql_plugin.cc:
  Rename alloc_mdl_locks to alloc_mdl_requests.
sql/sql_servers.cc:
  Rename alloc_mdl_locks to alloc_mdl_requests.
sql/sql_show.cc:
  Various changes to accommodate that lock requests are separated
  from lock tickets (granted locks).
sql/sql_table.cc:
  Various changes to accommodate that lock requests are separated
  from lock tickets (granted locks).
sql/sql_trigger.cc:
  Save reference to the lock ticket so it can be downgraded later.
sql/sql_udf.cc:
  Rename alloc_mdl_locks to alloc_mdl_requests.
sql/table.cc:
  Rename mdl_alloc_lock to mdl_request_alloc.
sql/table.h:
  Separate MDL lock requests from lock tickets (granted locks).
storage/myisammrg/ha_myisammrg.cc:
  Rename alloc_mdl_locks to alloc_mdl_requests.

Add two more files to .bzrignore.

.bzrignore:
  Ignore symlinks to new WL#4284 source and header files.

Add two more files to .bzrignore.

.bzrignore:
  Ignore symlinks to new WL#4284 source and header files.

----------------------------------------------------------
revno: 2617.22.7
committer: Konstantin Osipov <kostja@sun.com>
branch nick: mysql-6.0-runtime
timestamp: Tue 2009-01-27 16:41:58 +0300
message:
  WL#4284 "Transactional DDL locking" review.
  Improve a comment.


sql/mdl.cc:
  Improve a comment.

revno: 2617.22.4
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: mysql-6.0-runtime
timestamp: Mon 2009-01-26 15:19:14 -0200
message:
Move checks for OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN to a separate
helper function.


sql/ha_ndbcluster.cc:
  Use helper method to check transaction mode.
sql/log.cc:
  Use helper method to check transaction mode.
sql/sql_cache.cc:
  Use helper method to check transaction mode.
sql/sql_class.cc:
  Use helper method to check transaction mode.
sql/sql_class.h:
  Add helper method to check whether session is in a multi-statement
  transaction.
sql/sql_parse.cc:
  Use helper method to check transaction mode.
sql/transaction.cc:
  Use helper method to check transaction mode.

------------------------------------------------------------
revno: 3035.4.1
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 39897-6.0
timestamp: Thu 2009-01-15 12:17:57 -0200
message:
Bug#39897: lock_multi fails in pushbuild: timeout waiting for processlist

The problem is that relying on the "Table lock" thread state in
its current position to detect that a thread is waiting on a lock
is race prone. The "Table lock" state change happens before the
thread actually tries to grab a lock on a table.

The solution is to move the "Table lock" state so that its set
only when a thread is actually going to wait for a lock. The state
change happens after the thread fails to grab the lock (because it
is owned by other thread) and proceeds to wait on a condition.

This is considered part of work related to WL#4284 "Transactional
DDL locking"
Warning: this patch contains an incompatible change. 
When waiting on a lock in thr_lock.c, the server used to display "Locked"
processlist state. After this patch, the state is "Table lock".
The new state was actually intended to be display since year 2002,
when Monty added it. But up until removal of thd->locked boolean
member, this state was ignored by SHOW PROCESSLIST code.  

mysql-test/r/lock_multi.result:
  A style fix.
mysql-test/r/sp-threads.result:
  Changed output of SHOW PROCESSLIST (new wait state).
mysql-test/t/lock_multi.test:
  Use a more accurate state description when waiting inside thr_lock.c.
mysql-test/t/lock_sync.test:
  Use a more accurate state description when waiting inside thr_lock.c.
mysql-test/t/multi_update.test:
  Use a more accurate state description when waiting inside thr_lock.c.
mysql-test/t/query_cache_28249.test:
  Use a more accurate state description when waiting inside thr_lock.c.
mysql-test/t/sp_notembedded.test:
  Use a more accurate state description when waiting inside thr_lock.c.
mysql-test/t/status.test:
  Use a more accurate state description when waiting inside thr_lock.c.
mysys/thr_lock.c:
  Update thread state while waiting for a table lock.
sql/lock.cc:
  State change was moved inside thr_lock.c.

-----------------------------------------------------------
2497.479.10 Sergei Golubchik    2008-08-27
            proc_info_hook, mysys access to thd->proc_info

This patch is necessary for backport of WL#4284 "Transactional
DDL locking".


include/my_global.h:
  proc_info_hook
include/my_sys.h:
   proc_info_hook
mysys/my_static.c:
  proc_info_hook
sql/mysqld.cc:
  proc_info_hook
sql/sql_class.cc:
  proc_info_hook

------------------------------------------------------------
revno: 2630.22.3
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 4284-6.0
timestamp: Thu 2008-08-07 22:33:43 -0300
message:
WL#4284: Transactional DDL locking

Make transaction management more modular through a new interface.

The overall objective of this change is to provide groundwork
for the design of transactional DDL locking by cleaning up the
transaction high level API to better distinguish operations implicit
and explicit, and single statement transaction from operations on
the normal transaction.

Having a a high-level interface for transaction management provides
a better base for implementing transactional concepts that are not
always tied to storage engines and also makes it easier to interect
with other higher level modules of the server.

client/Makefile.am:
  Add new file to the build.
libmysqld/CMakeLists.txt:
  Add new file to the build.
libmysqld/Makefile.am:
  Add new file to the build.
sql/CMakeLists.txt:
  Add new file to the build.
sql/Makefile.am:
  Add new file to the build.
sql/handler.cc:
  Remove multiplexer commit or rollback function. Most callers already
  have enough information to decided whether to rollback or commit.
  Having plain and well named functions makes it easier to read
  and understand code.
sql/handler.h:
  Remove wrapper function as the low level transaction functions
  shouldn't be called directly anymore.
sql/log_event.cc:
  Rename transaction management functions to the new names.
sql/log_event_old.cc:
  Rename transaction management functions to the new names.
sql/mysql_priv.h:
  Remove obsolete functions for implicit and explicit commit.
sql/rpl_injector.cc:
  Rename transaction management functions to the new names.
sql/rpl_rli.cc:
  Rename transaction management functions to the new names.
sql/set_var.cc:
  Rename transaction management functions to the new names.
sql/slave.cc:
  Rename transaction management functions to the new names.
sql/sql_base.cc:
  Rename transaction management functions to the new names.
sql/sql_class.cc:
  Rename transaction management functions to the new names.
sql/sql_delete.cc:
  Rename transaction management functions to the new names.
sql/sql_do.cc:
  Rename transaction management functions to the new names.
sql/sql_insert.cc:
  Rename transaction management functions to the new names.
sql/sql_parse.cc:
  Rename transaction management functions to the new names.
sql/sql_partition.cc:
  Rename transaction management functions to the new names.
sql/sql_table.cc:
  Rename transaction management functions to the new names.
sql/transaction.cc:
  Implement wrapper functions to differentiate operations on
  the single statement transaction from the ones operating
  on the normal transaction.
sql/transaction.h:
  Export new functions for dealing with transaction commands.

------------------------------------------------------------
revno: 2630.13.17
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 4284-6.0
timestamp: Sun 2008-07-27 10:14:46 -0300
message:
Post-merge fixes:

Remove dependency on binlog, require not embedded as test uses
the event scheduler and disable abort on error for syntax only
available on servers built with debugging support.

This is a patch in scope of WL#4284 "Transactional DDL locking"

mysql-test/t/implicit_commit.test:
  Remove dependency on binlog, require not embedded as test uses
  the event scheduler and disable abort on error for syntax only
  available on servers built with debugging support.