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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''
109 lines
3.8 KiB
C++
109 lines
3.8 KiB
C++
/* Copyright (C) 2000,2004 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 heap handler */
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#include <heap.h>
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class ha_heap: public handler
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{
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HP_INFO *file;
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key_map btree_keys;
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/* number of records changed since last statistics update */
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uint records_changed;
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bool key_stats_ok;
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public:
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ha_heap(TABLE *table);
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~ha_heap() {}
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const char *table_type() const
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{
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return (table->in_use->variables.sql_mode & MODE_MYSQL323) ?
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"HEAP" : "MEMORY";
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}
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const char *index_type(uint inx)
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{
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return ((table->key_info[inx].algorithm == HA_KEY_ALG_BTREE) ? "BTREE" :
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"HASH");
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}
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const char **bas_ext() const;
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ulong table_flags() const
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{
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return (HA_FAST_KEY_READ | HA_NO_BLOBS | HA_NULL_IN_KEY |
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HA_REC_NOT_IN_SEQ | HA_READ_RND_SAME |
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HA_CAN_INSERT_DELAYED);
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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_BTREE) ?
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HA_READ_NEXT | HA_READ_PREV | HA_READ_ORDER | HA_READ_RANGE :
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HA_ONLY_WHOLE_INDEX);
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}
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const key_map *keys_to_use_for_scanning() { return &btree_keys; }
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uint max_supported_keys() const { return MAX_KEY; }
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uint max_supported_key_part_length() const { return MAX_KEY_LENGTH; }
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double scan_time() { return (double) (records+deleted) / 20.0+10; }
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double read_time(uint index, uint ranges, ha_rows rows)
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{ return (double) rows / 20.0+1; }
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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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void set_keys_for_scanning(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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ulonglong get_auto_increment();
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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 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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void info(uint);
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int extra(enum ha_extra_function operation);
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int external_lock(THD *thd, int lock_type);
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int delete_all_rows(void);
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int disable_indexes(uint mode);
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int enable_indexes(uint mode);
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int indexes_are_disabled(void);
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ha_rows records_in_range(uint inx, key_range *min_key, key_range *max_key);
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int delete_table(const char *from);
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int rename_table(const char * from, const char * to);
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int create(const char *name, TABLE *form, HA_CREATE_INFO *create_info);
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void update_create_info(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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int cmp_ref(const byte *ref1, const byte *ref2)
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{
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HEAP_PTR ptr1=*(HEAP_PTR*)ref1;
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HEAP_PTR ptr2=*(HEAP_PTR*)ref2;
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return ptr1 < ptr2? -1 : (ptr1 > ptr2? 1 : 0);
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}
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private:
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void update_key_stats();
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};
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