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de6f5ae5ab
The idea of the patch
is that every cursor gets its own lock id for table level locking.
Thus cursors are protected from updates performed within the same
connection. Additionally a list of transient (must be closed at
commit) cursors is maintained and all transient cursors are closed
when necessary. Lastly, this patch adds support for deadlock
timeouts to TLL locking when using cursors.
+ post-review fixes.
include/thr_lock.h:
- add a notion of lock owner to table level locking. When using
cursors, lock owner can not be identified by a thread id any more,
as we must protect cursors from updates issued within the same
connection (thread). So, each cursor has its own lock identifier to
use with table level locking.
- extend return values of thr_lock and thr_multi_lock with
THR_LOCK_TIMEOUT and THR_LOCK_DEADLOCK, since these conditions
are now possible (see comments to thr_lock.c)
mysys/thr_lock.c:
Better support for cursors:
- use THR_LOCK_OWNER * as lock identifier, not pthread_t.
- check and return an error for a trivial deadlock case, when an
update statement is issued to a table locked by a cursor which has
been previously opened in the same connection.
- add support for locking timeouts: with use of cursors, trivial
deadlocks can occur. For now the only remedy is the lock wait timeout,
which is initialized from a new global variable 'table_lock_wait_timeout'
Example of a deadlock (assuming the storage engine does not downgrade
locks):
con1: open cursor for select * from t1;
con2: open cursor for select * from t2;
con1: update t2 set id=id*2; -- blocked
con2: update t1 set id=id*2; -- deadlock
Lock timeouts are active only if a connection is using cursors.
- the check in the wait_for_lock loop has been changed from
data->cond != cond to data->cond != 0. data->cond is zeroed
in every place it's changed.
- added comments
sql/examples/ha_archive.cc:
- extend the handlerton with the info about cursor behaviour at commit.
sql/examples/ha_archive.h:
- ctor moved to .cc to make use of archive handlerton
sql/examples/ha_example.cc:
- add handlerton instance, init handler::ht with it
sql/examples/ha_example.h:
- ctor moved to .cc to make use of ha_example handlerton
sql/examples/ha_tina.cc:
- add handlerton instance, init handler::ht with it
sql/examples/ha_tina.h:
- ctor moved to .cc to make use of CSV handlerton
sql/ha_berkeley.cc:
- init handlerton::flags and handler::ht
sql/ha_berkeley.h:
- ctor moved to .cc to make use of BerkeleyDB handlerton
sql/ha_blackhole.cc:
- add handlerton instance, init handler::ht with it
sql/ha_blackhole.h:
- ctor moved to .cc to make use of blackhole handlerton
sql/ha_federated.cc:
- add handlerton instance, init handler::ht with it
sql/ha_federated.h:
- ctor moved to .cc to make use of federated handlerton
sql/ha_heap.cc:
- add handlerton instance, init handler::ht with it
sql/ha_heap.h:
- ctor moved to .cc to make use of ha_heap handlerton
sql/ha_innodb.cc:
- init handlerton::flags and handler::ht of innobase storage engine
sql/ha_innodb.h:
- ctor moved to .cc to make use of archive handlerton
sql/ha_myisam.cc:
- add handlerton instance, init handler::ht with it
sql/ha_myisam.h:
- ctor moved to .cc to make use of MyISAM handlerton
sql/ha_myisammrg.cc:
- init handler::ht in the ctor
sql/ha_myisammrg.h:
- ctor moved to .cc to make use of MyISAM MERGE handlerton
sql/ha_ndbcluster.cc:
- init handlerton::flags and handler::ht
sql/handler.cc:
- drop support for ISAM storage engine, which was removed from 5.0
- close all "transient" cursors at COMMIT/ROLLBACK. A "transient"
SQL level cursor is a cursor that uses tables that have a transaction-
specific state.
sql/handler.h:
- extend struct handlerton with flags, add handlerton *ht to every
handler instance.
sql/lock.cc:
- extend mysql_lock_tables to send error to the client if
thr_multi_lock returns a timeout or a deadlock error.
sql/mysqld.cc:
- add server option --table_lock_wait_timeout (in seconds)
sql/set_var.cc:
- add new global variable 'table_lock_wait_timeout' to specify
a wait timeout for table-level locks of MySQL (in seconds). The default
timeout is 50 seconds. The timeout is active only if the connection
has open cursors.
sql/sql_class.cc:
- implement Statement_map::close_transient_cursors
- safety suggests that we need an assert ensuring
llock_info->n_cursors is functioning properly, adjust destruction of
the Statement_map to allow such assert in THD::~THD
sql/sql_class.h:
- add support for Cursors registry to Statement map.
sql/sql_prepare.cc:
- maintain a list of cursors that must be closed at commit/rollback.
sql/sql_select.cc:
- extend class Cursor to support specific at-COMMIT/ROLLBACK behavior.
If a cursor uses tables of a storage engine that
invalidates all open tables at COMMIT/ROLLBACK, it must be closed
before COMMIT/ROLLBACK is executed.
sql/sql_select.h:
- add an own lock_id and commit/rollback status flag to class Cursor
tests/mysql_client_test.c:
A test case for Bug#10760 and complementary issues: test a simple
deadlock case too.
mysql-test/var:
New BitKeeper file ``mysql-test/var''
85 lines
3.3 KiB
C++
85 lines
3.3 KiB
C++
/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#ifdef USE_PRAGMA_INTERFACE
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#pragma interface /* gcc class implementation */
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#endif
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/* class for the the myisam merge handler */
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#include <myisammrg.h>
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class ha_myisammrg: public handler
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{
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MYRG_INFO *file;
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public:
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ha_myisammrg(TABLE *table_arg);
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~ha_myisammrg() {}
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const char *table_type() const { return "MRG_MyISAM"; }
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const char **bas_ext() const;
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const char *index_type(uint key_number);
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ulong table_flags() const
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{
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return (HA_REC_NOT_IN_SEQ | HA_AUTO_PART_KEY | HA_READ_RND_SAME |
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HA_NULL_IN_KEY | HA_CAN_INDEX_BLOBS | HA_FILE_BASED |
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HA_CAN_INSERT_DELAYED | HA_ANY_INDEX_MAY_BE_UNIQUE);
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}
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ulong index_flags(uint inx, uint part, bool all_parts) const
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{
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return ((table->key_info[inx].algorithm == HA_KEY_ALG_FULLTEXT) ?
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0 : HA_READ_NEXT | HA_READ_PREV | HA_READ_RANGE |
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HA_READ_ORDER | HA_KEYREAD_ONLY);
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}
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uint max_supported_keys() const { return MI_MAX_KEY; }
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uint max_supported_key_length() const { return MI_MAX_KEY_LENGTH; }
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uint max_supported_key_part_length() const { return MI_MAX_KEY_LENGTH; }
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double scan_time()
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{ return ulonglong2double(data_file_length) / IO_SIZE + file->tables; }
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int open(const char *name, int mode, uint test_if_locked);
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int close(void);
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int write_row(byte * buf);
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int update_row(const byte * old_data, byte * new_data);
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int delete_row(const byte * buf);
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int index_read(byte * buf, const byte * key,
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uint key_len, enum ha_rkey_function find_flag);
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int index_read_idx(byte * buf, uint idx, const byte * key,
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uint key_len, enum ha_rkey_function find_flag);
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int index_read_last(byte * buf, const byte * key, uint key_len);
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int index_next(byte * buf);
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int index_prev(byte * buf);
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int index_first(byte * buf);
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int index_last(byte * buf);
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int index_next_same(byte *buf, const byte *key, uint keylen);
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int rnd_init(bool scan);
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int rnd_next(byte *buf);
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int rnd_pos(byte * buf, byte *pos);
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void position(const byte *record);
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ha_rows records_in_range(uint inx, key_range *min_key, key_range *max_key);
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void info(uint);
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int extra(enum ha_extra_function operation);
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int extra_opt(enum ha_extra_function operation, ulong cache_size);
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int external_lock(THD *thd, int lock_type);
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uint lock_count(void) const;
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int create(const char *name, TABLE *form, HA_CREATE_INFO *create_info);
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THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,
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enum thr_lock_type lock_type);
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void update_create_info(HA_CREATE_INFO *create_info);
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void append_create_info(String *packet);
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MYRG_INFO *myrg_info() { return file; }
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};
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