mariadb/storage/myisam/ha_myisam.h
unknown 4462578a1c WL#3984 (Revise locking of mysql.general_log and mysql.slow_log)
Bug#25422 (Hang with log tables)
Bug 17876 (Truncating mysql.slow_log in a SP after using cursor locks the
          thread)
Bug 23044 (Warnings on flush of a log table)
Bug 29129 (Resetting general_log while the GLOBAL READ LOCK is set causes
           a deadlock)

Prior to this fix, the server would hang when performing concurrent
ALTER TABLE or TRUNCATE TABLE statements against the LOG TABLES,
which are mysql.general_log and mysql.slow_log.

The root cause traces to the following code:
in sql_base.cc, open_table()
  if (table->in_use != thd)
  {
    /* wait_for_condition will unlock LOCK_open for us */
    wait_for_condition(thd, &LOCK_open, &COND_refresh);
  }
The problem with this code is that the current implementation of the
LOGGER creates 'fake' THD objects, like
- Log_to_csv_event_handler::general_log_thd
- Log_to_csv_event_handler::slow_log_thd
which are not associated to a real thread running in the server,
so that waiting for these non-existing threads to release table locks
cause the dead lock.

In general, the design of Log_to_csv_event_handler does not fit into the
general architecture of the server, so that the concept of general_log_thd
and slow_log_thd has to be abandoned:
- this implementation does not work with table locking
- it will not work with commands like SHOW PROCESSLIST
- having the log tables always opened does not integrate well with DDL
operations / FLUSH TABLES / SET GLOBAL READ_ONLY

With this patch, the fundamental design of the LOGGER has been changed to:
- always open and close a log table when writing a log
- remove totally the usage of fake THD objects
- clarify how locking of log tables is implemented in general.

See WL#3984 for details related to the new locking design.

Additional changes (misc bugs exposed and fixed):

1)

mysqldump which would ignore some tables in dump_all_tables_in_db(),
 but forget to ignore the same in dump_all_views_in_db().

2)

mysqldump would also issue an empty "LOCK TABLE" command when all the tables
to lock are to be ignored (numrows == 0), instead of not issuing the query.

3)

Internal errors handlers could intercept errors but not warnings
(see sql_error.cc).

4)

Implementing a nested call to open tables, for the performance schema tables,
exposed an existing bug in remove_table_from_cache(), which would perform:
  in_use->some_tables_deleted=1;
against another thread, without any consideration about thread locking.
This call inside remove_table_from_cache() was not required anyway,
since calling mysql_lock_abort() takes care of aborting -- cleanly -- threads
that might hold a lock on a table.
This line (in_use->some_tables_deleted=1) has been removed.


sql/handler.cc:
  Moved logic for system / log tables in the SQL layer.
sql/handler.h:
  Moved logic for system / log tables in the SQL layer.
sql/lock.cc:
  Revised locking of log tables
sql/log.cc:
  Major cleanup: changed how log tables are locked / written to.
sql/log.h:
  Major cleanup: changed how log tables are locked / written to.
sql/mysql_priv.h:
  performance schema helpers
sql/slave.cc:
  open_ltable() lock flags
sql/sp.cc:
  open_ltable() lock flags
sql/sql_acl.cc:
  open_ltable() lock flags
sql/sql_class.h:
  performance schema helpers
sql/sql_delete.cc:
  log tables cleanup in TRUNCATE
sql/sql_error.cc:
  Internal handlers can also intercept warnings
sql/sql_insert.cc:
  open_ltable() lock flags
sql/sql_parse.cc:
  performance schema helpers
sql/sql_plugin.cc:
  open_ltable() lock flags
sql/sql_rename.cc:
  log tables cleanup in RENAME
sql/sql_servers.cc:
  open_ltable() lock flags
sql/sql_show.cc:
  Move INFORMATION_SCHEMA_NAME to table.cc
sql/sql_table.cc:
  log tables cleanup (admin operations, ALTER TABLE)
sql/sql_udf.cc:
  open_ltable() lock flags
sql/table.cc:
  Implemented TABLE_CATEGORY.
sql/share/errmsg.txt:
  Changed the wording and name of ER_CANT_READ_LOCK_LOG_TABLE
sql/table.h:
  Implemented TABLE_CATEGORY.
storage/csv/ha_tina.cc:
  Moved logic for system / log tables in the SQL layer.
storage/csv/ha_tina.h:
  Moved logic for system / log tables in the SQL layer.
storage/myisam/ha_myisam.cc:
  Moved logic for system / log tables in the SQL layer.
storage/myisam/ha_myisam.h:
  Moved logic for system / log tables in the SQL layer.
client/mysqldump.c:
  Don't lock tables in the ignore list.
  Don't issue empty LOCK TABLES queries.
sql/sql_base.cc:
  log tables cleanup
  performance schema helpers
mysql-test/r/ps.result:
  Adjust test results
mysql-test/r/show_check.result:
  Adjust test results
mysql-test/r/status.result:
  Adjust test results
mysql-test/t/log_state.test:
  Added tests for Bug#29129
mysql-test/t/ps.test:
  Make the test output deterministic
mysql-test/t/show_check.test:
  Make the test output deterministic
mysql-test/r/log_state.result:
  Changed the default location of the log output to LOG_FILE,
  for backward compatibility with MySQL 5.0
  ---
  Adjust test results
mysql-test/r/log_tables.result:
  cleanup for -ps-protocol
mysql-test/t/log_tables.test:
  cleanup for -ps-protocol
sql/set_var.cc:
  Changed the default location of the log output to LOG_FILE,
  for backward compatibility with MySQL 5.0
  ---
  log tables cleanup
2007-07-27 00:31:06 -06:00

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/* Copyright (C) 2000-2006 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifdef USE_PRAGMA_INTERFACE
#pragma interface /* gcc class implementation */
#endif
/* class for the the myisam handler */
#include <myisam.h>
#include <ft_global.h>
#define HA_RECOVER_NONE 0 /* No automatic recover */
#define HA_RECOVER_DEFAULT 1 /* Automatic recover active */
#define HA_RECOVER_BACKUP 2 /* Make a backupfile on recover */
#define HA_RECOVER_FORCE 4 /* Recover even if we loose rows */
#define HA_RECOVER_QUICK 8 /* Don't check rows in data file */
extern ulong myisam_sort_buffer_size;
extern TYPELIB myisam_recover_typelib;
extern ulong myisam_recover_options;
class ha_myisam: public handler
{
MI_INFO *file;
ulonglong int_table_flags;
char *data_file_name, *index_file_name;
bool can_enable_indexes;
int repair(THD *thd, MI_CHECK &param, bool optimize);
public:
ha_myisam(handlerton *hton, TABLE_SHARE *table_arg);
~ha_myisam() {}
handler *clone(MEM_ROOT *mem_root);
const char *table_type() const { return "MyISAM"; }
const char *index_type(uint key_number);
const char **bas_ext() const;
ulonglong table_flags() const { return int_table_flags; }
ulong index_flags(uint inx, uint part, bool all_parts) const
{
return ((table_share->key_info[inx].algorithm == HA_KEY_ALG_FULLTEXT) ?
0 : HA_READ_NEXT | HA_READ_PREV | HA_READ_RANGE |
HA_READ_ORDER | HA_KEYREAD_ONLY);
}
uint max_supported_keys() const { return MI_MAX_KEY; }
uint max_supported_key_length() const { return MI_MAX_KEY_LENGTH; }
uint max_supported_key_part_length() const { return MI_MAX_KEY_LENGTH; }
uint checksum() const;
int open(const char *name, int mode, uint test_if_locked);
int close(void);
int write_row(uchar * buf);
int update_row(const uchar * old_data, uchar * new_data);
int delete_row(const uchar * buf);
int index_read(uchar *buf, const uchar *key, key_part_map keypart_map,
enum ha_rkey_function find_flag);
int index_read_idx(uchar *buf, uint index, const uchar *key,
key_part_map keypart_map, enum ha_rkey_function find_flag);
int index_read_last(uchar *buf, const uchar *key, key_part_map keypart_map);
int index_next(uchar * buf);
int index_prev(uchar * buf);
int index_first(uchar * buf);
int index_last(uchar * buf);
int index_next_same(uchar *buf, const uchar *key, uint keylen);
int ft_init()
{
if (!ft_handler)
return 1;
ft_handler->please->reinit_search(ft_handler);
return 0;
}
FT_INFO *ft_init_ext(uint flags, uint inx,String *key)
{
return ft_init_search(flags,file,inx,
(uchar *)key->ptr(), key->length(), key->charset(),
table->record[0]);
}
int ft_read(uchar *buf);
int rnd_init(bool scan);
int rnd_next(uchar *buf);
int rnd_pos(uchar * buf, uchar *pos);
int restart_rnd_next(uchar *buf, uchar *pos);
void position(const uchar *record);
int info(uint);
int extra(enum ha_extra_function operation);
int extra_opt(enum ha_extra_function operation, ulong cache_size);
int reset(void);
int external_lock(THD *thd, int lock_type);
int delete_all_rows(void);
int disable_indexes(uint mode);
int enable_indexes(uint mode);
int indexes_are_disabled(void);
void start_bulk_insert(ha_rows rows);
int end_bulk_insert();
ha_rows records_in_range(uint inx, key_range *min_key, key_range *max_key);
void update_create_info(HA_CREATE_INFO *create_info);
int create(const char *name, TABLE *form, HA_CREATE_INFO *create_info);
THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,
enum thr_lock_type lock_type);
virtual void get_auto_increment(ulonglong offset, ulonglong increment,
ulonglong nb_desired_values,
ulonglong *first_value,
ulonglong *nb_reserved_values);
int rename_table(const char * from, const char * to);
int delete_table(const char *name);
int check(THD* thd, HA_CHECK_OPT* check_opt);
int analyze(THD* thd,HA_CHECK_OPT* check_opt);
int repair(THD* thd, HA_CHECK_OPT* check_opt);
bool check_and_repair(THD *thd);
bool is_crashed() const;
bool auto_repair() const { return myisam_recover_options != 0; }
int optimize(THD* thd, HA_CHECK_OPT* check_opt);
int restore(THD* thd, HA_CHECK_OPT* check_opt);
int backup(THD* thd, HA_CHECK_OPT* check_opt);
int assign_to_keycache(THD* thd, HA_CHECK_OPT* check_opt);
int preload_keys(THD* thd, HA_CHECK_OPT* check_opt);
bool check_if_incompatible_data(HA_CREATE_INFO *info, uint table_changes);
#ifdef HAVE_REPLICATION
int dump(THD* thd, int fd);
int net_read_dump(NET* net);
#endif
#ifdef HAVE_QUERY_CACHE
my_bool register_query_cache_table(THD *thd, char *table_key,
uint key_length,
qc_engine_callback
*engine_callback,
ulonglong *engine_data);
#endif
};