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mariadb/sql/sql_base.h
Dmitry Lenev 00496b7acd Fix for bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH 
TABLES <list> WITH READ LOCK are incompatible".

The problem was that FLUSH TABLES <list> WITH READ LOCK
which was issued when other connection has acquired global
read lock using FLUSH TABLES WITH READ LOCK was blocked
and has to wait until global read lock is released.

This issue stemmed from the fact that FLUSH TABLES <list>
WITH READ LOCK implementation has acquired X metadata locks
on tables to be flushed. Since these locks required acquiring
of global IX lock this statement was incompatible with global
read lock.

This patch addresses problem by using SNW metadata type of
lock for tables to be flushed by FLUSH TABLES <list> WITH
READ LOCK. It is OK to acquire them without global IX lock
as long as we won't try to upgrade those locks. Since SNW
locks allow concurrent statements using same table FLUSH
TABLE <list> WITH READ LOCK now has to wait until old
versions of tables to be flushed go away after acquiring
metadata locks. Since such waiting can lead to deadlock
MDL deadlock detector was extended to take into account
waits for flush and resolve such deadlocks.

As a bonus code in open_tables() which was responsible for
waiting old versions of tables to go away was refactored.
Now when we encounter old version of table in open_table()
we don't back-off and wait for all old version to go away,
but instead wait for this particular table to be flushed.
Such approach supported by deadlock detection should reduce
number of scenarios in which FLUSH TABLES aborts concurrent
multi-statement transactions.

Note that active FLUSH TABLES <list> WITH READ LOCK still
blocks concurrent FLUSH TABLES WITH READ LOCK statement
as the former keeps tables open and thus prevents the
latter statement from doing flush.

mysql-test/include/handler.inc:
  Adjusted test case after changing status which is set
  when FLUSH TABLES waits for tables to be flushed from
  "Flushing tables" to "Waiting for table".
mysql-test/r/flush.result:
  Added test which checks that "flush tables <list> with
  read lock" is compatible with active "flush tables with
  read lock" but not vice-versa. This test also covers
  bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES
  <list> WITH READ LOCK are incompatible".
mysql-test/r/mdl_sync.result:
  Added scenarios in which wait for table to be flushed
  causes deadlocks to the coverage of MDL deadlock detector.
mysql-test/suite/perfschema/r/dml_setup_instruments.result:
  Adjusted test results after removal of COND_refresh
  condition variable.
mysql-test/suite/perfschema/r/server_init.result:
  Adjusted test and its results after removal of COND_refresh
  condition variable.
mysql-test/suite/perfschema/t/server_init.test:
  Adjusted test and its results after removal of COND_refresh
  condition variable.
mysql-test/t/flush.test:
  Added test which checks that "flush tables <list> with
  read lock" is compatible with active "flush tables with
  read lock" but not vice-versa. This test also covers
  bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES
  <list> WITH READ LOCK are incompatible".
mysql-test/t/kill.test:
  Adjusted test case after changing status which is set
  when FLUSH TABLES waits for tables to be flushed from
  "Flushing tables" to "Waiting for table".
mysql-test/t/lock_multi.test:
  Adjusted test case after changing status which is set
  when FLUSH TABLES waits for tables to be flushed from
  "Flushing tables" to "Waiting for table".
mysql-test/t/mdl_sync.test:
  Added scenarios in which wait for table to be flushed
  causes deadlocks to the coverage of MDL deadlock detector.
sql/ha_ndbcluster.cc:
  Adjusted code after adding one more parameter for
  close_cached_tables() call - timeout for waiting for
  table to be flushed.
sql/ha_ndbcluster_binlog.cc:
  Adjusted code after adding one more parameter for
  close_cached_tables() call - timeout for waiting for
  table to be flushed.
sql/lock.cc:
  Removed COND_refresh condition variable. See comment
  for sql_base.cc for details.
sql/mdl.cc:
  Now MDL deadlock detector takes into account information
  about waits for table flushes when searching for deadlock.
  To implement this change:
  - Declaration of enum_deadlock_weight and
    Deadlock_detection_visitor were moved to mdl.h header
    to make them available to the code in table.cc which
    implements deadlock detector traversal through edges
    of waiters graph representing waiting for flush.
  - Since now MDL_context may wait not only for metadata
    lock but also for table to be flushed an abstract
    Wait_for_edge class was introduced. Its descendants
    MDL_ticket and Flush_ticket incapsulate specifics
    of inspecting waiters graph when following through
    edge representing wait of particular type.
  
  We no longer require global IX metadata lock when acquiring
  SNW or SNRW locks. Such locks are needed only when metadata
  locks of these types are upgraded to X locks. This allows
  to use SNW locks in FLUSH TABLES <list> WITH READ LOCK
  implementation and keep the latter compatible with global
  read lock.
sql/mdl.h:
  Now MDL deadlock detector takes into account information
  about waits for table flushes when searching for deadlock.
  To implement this change:
  - Declaration of enum_deadlock_weight and
    Deadlock_detection_visitor were moved to mdl.h header
    to make them available to the code in table.cc which
    implements deadlock detector traversal through edges
    of waiters graph representing waiting for flush.
  - Since now MDL_context may wait not only for metadata
    lock but also for table to be flushed an abstract
    Wait_for_edge class was introduced. Its descendants
    MDL_ticket and Flush_ticket incapsulate specifics
    of inspecting waiters graph when following through
    edge representing wait of particular type.
  - Deadlock_detection_visitor now has m_table_shares_visited
    member which allows to support recursive locking for
    LOCK_open. This is required when deadlock detector
    inspects waiters graph which contains several edges
    representing waits for flushes or needs to come through
    the such edge more than once.
sql/mysqld.cc:
  Removed COND_refresh condition variable. See comment
  for sql_base.cc for details.
sql/mysqld.h:
  Removed COND_refresh condition variable. See comment
  for sql_base.cc for details.
sql/sql_base.cc:
  Changed approach to how threads are waiting for table
  to be flushed. Now thread that wants to wait for old
  table to go away subscribes for notification by adding
  Flush_ticket to table's share and waits using
  MDL_context::m_wait object. Once table gets flushed
  (i.e. all tables are closed and table share is ready
  to be destroyed) all such waiters are notified
  individually.
  Thanks to this change MDL deadlock detector can take
  such waits into account.
  
  To implement this/as result of this change:
  - tdc_wait_for_old_versions() was replaced with
    tdc_wait_for_old_version() which waits for individual
    old share to go away and which is called by open_table()
    after finding out that share is outdated. We don't
    need to perform back-off before such waiting thanks
    to the fact that deadlock detector now sees such waits.
  - As result Open_table_ctx::m_mdl_requests became
    unnecessary and was removed. We no longer allocate
    copies of MDL_request objects on MEM_ROOT when
    MYSQL_OPEN_FORCE_SHARED/SHARED_HIGH_PRIO flags are
    in effect.
  - close_cached_tables() and tdc_wait_for_old_version()
    share code which implements waiting for share to be
    flushed - the both use TABLE_SHARE::wait_until_flush()
    method. Thanks to this close_cached_tables() supports
    timeouts and has extra parameter for this.
  - Open_table_context::OT_MDL_CONFLICT enum element was
    renamed to OT_CONFLICT as it is now also used in cases
    when back-off is required to resolve deadlock caused
    by waiting for flush and not metadata lock.
  - In cases when we discover that current connection tries
    to open tables from different generation we now simply
    back-off and restart process of opening tables. To
    support this Open_table_context::OT_REOPEN_TABLES enum
    element was added.
  - COND_refresh condition variable became unnecessary and
    was removed.
  - mysql_notify_thread_having_shared_lock() no longer wakes
    up connections waiting for flush as all such connections
    can be waken up by deadlock detector if necessary.
sql/sql_base.h:
  - close_cached_tables() now has one more parameter -
    timeout for waiting for table to be flushed.
  - Open_table_context::OT_MDL_CONFLICT enum element was
    renamed to OT_CONFLICT as it is now also used in cases
    when back-off is required to resolve deadlock caused
    by waiting for flush and not metadata lock.
    Added new OT_REOPEN_TABLES enum element to be used in
    cases when we need to restart open tables process even
    in the middle of transaction.
  - Open_table_ctx::m_mdl_requests became unnecessary and
    was removed.
sql/sql_class.h:
  Added assert ensuring that we won't use LOCK_open mutex
  with THD::enter_cond(). Otherwise deadlocks can arise in
  MDL deadlock detector.
sql/sql_parse.cc:
  Changed FLUSH TABLES <list> WITH READ LOCK to take SNW
  metadata locks instead of X locks on tables to be flushed.
  Since we no longer require global IX lock to be taken
  when SNW locks are taken this makes this statement
  compatible with FLUSH TABLES WITH READ LOCK statement.
  Since SNW locks allow other connections to have table
  opened FLUSH TABLES <list> WITH READ LOCK now has to
  wait during open_tables() for old version to go away.
  Such waits can lead to deadlocks which will be detected
  by MDL deadlock detector which now takes waits for table
  to be flushed into account.
  
  Also adjusted code after adding one more parameter for
  close_cached_tables() call - timeout for waiting for
  table to be flushed.
sql/sql_yacc.yy:
  FLUSH TABLES <list> WITH READ LOCK now needs only SNW
  metadata locks on tables.
sql/sys_vars.cc:
  Adjusted code after adding one more parameter for
  close_cached_tables() call - timeout for waiting for
  table to be flushed.
sql/table.cc:
  Implemented new approach to how threads are waiting for
  table to be flushed. Now thread that wants to wait for
  old table to go away subscribes for notification by
  adding Flush_ticket to table's share and waits using
  MDL_context::m_wait object. Once table gets flushed
  (i.e. all tables are closed and table share is ready
  to be destroyed) all such waiters are notified
  individually. This change allows to make such waits
  visible inside of MDL deadlock detector.
  To do it:
  
  - Added list of waiters/Flush_tickets to TABLE_SHARE
    class.
  - Changed free_table_share() to postpone freeing of
    share memory until last waiter goes away and to
    wake up subscribed waiters.
  - Added TABLE_SHARE::wait_until_flushed() method which
    implements subscription to the list of waiters for
    table to be flushed and waiting for this event.
  
  Implemented interface which allows to expose waits for
  flushes to MDL deadlock detector:
  
  - Introduced Flush_ticket class a descendant of
    Wait_for_edge class.
  - Added TABLE_SHARE::find_deadlock() method which allows
    deadlock detector to find out what contexts are still
    using old version of table in question (i.e. to find
    out what contexts are waited for by owner of
    Flush_ticket).
sql/table.h:
  In order to support new strategy of waiting for table flush
  (see comment for table.cc for details) added list of
  waiters/Flush_tickets to TABLE_SHARE class.
  
  Implemented interface which allows to expose waits for
  flushes to MDL deadlock detector:
  - Introduced Flush_ticket class a descendant of
    Wait_for_edge class.
  - Added TABLE_SHARE::find_deadlock() method which allows
    deadlock detector to find out what contexts are still
    using old version of table in question (i.e. to find
    out what contexts are waited for by owner of
    Flush_ticket).
2010-07-27 17:34:58 +04:00

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/* Copyright 2006-2008 MySQL AB, 2008-2009 Sun Microsystems, Inc.
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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
#ifndef SQL_BASE_INCLUDED
#define SQL_BASE_INCLUDED
#include "unireg.h" // REQUIRED: for other includes
#include "table.h" /* open_table_mode */
#include "sql_trigger.h" /* trg_event_type */
#include "sql_class.h" /* enum_mark_columns */
#include "mysqld.h" /* key_map */
class Item_ident;
struct Name_resolution_context;
class Open_table_context;
class Open_tables_state;
class Prelocking_strategy;
struct TABLE_LIST;
class THD;
struct handlerton;
struct TABLE;
typedef class st_select_lex SELECT_LEX;
typedef struct st_lock_param_type ALTER_PARTITION_PARAM_TYPE;
/*
This enumeration type is used only by the function find_item_in_list
to return the info on how an item has been resolved against a list
of possibly aliased items.
The item can be resolved:
- against an alias name of the list's element (RESOLVED_AGAINST_ALIAS)
- against non-aliased field name of the list (RESOLVED_WITH_NO_ALIAS)
- against an aliased field name of the list (RESOLVED_BEHIND_ALIAS)
- ignoring the alias name in cases when SQL requires to ignore aliases
(e.g. when the resolved field reference contains a table name or
when the resolved item is an expression) (RESOLVED_IGNORING_ALIAS)
*/
enum enum_resolution_type {
NOT_RESOLVED=0,
RESOLVED_IGNORING_ALIAS,
RESOLVED_BEHIND_ALIAS,
RESOLVED_WITH_NO_ALIAS,
RESOLVED_AGAINST_ALIAS
};
enum find_item_error_report_type {REPORT_ALL_ERRORS, REPORT_EXCEPT_NOT_FOUND,
IGNORE_ERRORS, REPORT_EXCEPT_NON_UNIQUE,
IGNORE_EXCEPT_NON_UNIQUE};
enum enum_tdc_remove_table_type {TDC_RT_REMOVE_ALL, TDC_RT_REMOVE_NOT_OWN,
TDC_RT_REMOVE_UNUSED};
/* bits for last argument to remove_table_from_cache() */
#define RTFC_NO_FLAG 0x0000
#define RTFC_OWNED_BY_THD_FLAG 0x0001
#define RTFC_WAIT_OTHER_THREAD_FLAG 0x0002
#define RTFC_CHECK_KILLED_FLAG 0x0004
bool check_dup(const char *db, const char *name, TABLE_LIST *tables);
bool table_cache_init(void);
void table_cache_free(void);
bool table_def_init(void);
void table_def_free(void);
void table_def_start_shutdown(void);
void assign_new_table_id(TABLE_SHARE *share);
uint cached_open_tables(void);
uint cached_table_definitions(void);
uint create_table_def_key(THD *thd, char *key, TABLE_LIST *table_list,
bool tmp_table);
TABLE_SHARE *get_table_share(THD *thd, TABLE_LIST *table_list, char *key,
uint key_length, uint db_flags, int *error,
my_hash_value_type hash_value);
void release_table_share(TABLE_SHARE *share);
TABLE_SHARE *get_cached_table_share(const char *db, const char *table_name);
TABLE *open_ltable(THD *thd, TABLE_LIST *table_list, thr_lock_type update,
uint lock_flags);
bool open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root,
Open_table_context *ot_ctx);
bool name_lock_locked_table(THD *thd, TABLE_LIST *tables);
bool reopen_name_locked_table(THD* thd, TABLE_LIST* table_list, bool link_in);
TABLE *table_cache_insert_placeholder(THD *thd, const char *key,
uint key_length);
bool lock_table_name_if_not_cached(THD *thd, const char *db,
const char *table_name, TABLE **table);
void detach_merge_children(TABLE *table, bool clear_refs);
bool fix_merge_after_open(TABLE_LIST *old_child_list, TABLE_LIST **old_last,
TABLE_LIST *new_child_list, TABLE_LIST **new_last);
bool reopen_table(TABLE *table);
bool reopen_tables(THD *thd,bool get_locks,bool in_refresh);
void close_data_files_and_morph_locks(THD *thd, const char *db,
const char *table_name);
void close_handle_and_leave_table_as_lock(TABLE *table);
bool open_new_frm(THD *thd, TABLE_SHARE *share, const char *alias,
uint db_stat, uint prgflag,
uint ha_open_flags, TABLE *outparam, TABLE_LIST *table_desc,
MEM_ROOT *mem_root);
bool wait_for_tables(THD *thd);
bool table_is_used(TABLE *table, bool wait_for_name_lock);
TABLE *drop_locked_tables(THD *thd,const char *db, const char *table_name);
void abort_locked_tables(THD *thd,const char *db, const char *table_name);
bool get_key_map_from_key_list(key_map *map, TABLE *table,
List<String> *index_list);
TABLE *open_temporary_table(THD *thd, const char *path, const char *db,
const char *table_name, bool link_in_list);
TABLE *find_locked_table(TABLE *list, const char *db, const char *table_name);
TABLE *find_write_locked_table(TABLE *list, const char *db,
const char *table_name);
thr_lock_type read_lock_type_for_table(THD *thd,
Query_tables_list *prelocking_ctx,
TABLE_LIST *table_list);
my_bool mysql_rm_tmp_tables(void);
bool rm_temporary_table(handlerton *base, char *path);
void close_tables_for_reopen(THD *thd, TABLE_LIST **tables,
MDL_ticket *start_of_statement_svp);
TABLE_LIST *find_table_in_list(TABLE_LIST *table,
TABLE_LIST *TABLE_LIST::*link,
const char *db_name,
const char *table_name);
TABLE *find_temporary_table(THD *thd, const char *db, const char *table_name);
TABLE *find_temporary_table(THD *thd, TABLE_LIST *table_list);
void close_thread_tables(THD *thd);
bool fill_record_n_invoke_before_triggers(THD *thd, List<Item> &fields,
List<Item> &values,
bool ignore_errors,
Table_triggers_list *triggers,
enum trg_event_type event);
bool fill_record_n_invoke_before_triggers(THD *thd, Field **field,
List<Item> &values,
bool ignore_errors,
Table_triggers_list *triggers,
enum trg_event_type event);
bool insert_fields(THD *thd, Name_resolution_context *context,
const char *db_name, const char *table_name,
List_iterator<Item> *it, bool any_privileges);
int setup_wild(THD *thd, TABLE_LIST *tables, List<Item> &fields,
List<Item> *sum_func_list, uint wild_num);
bool setup_fields(THD *thd, Item** ref_pointer_array,
List<Item> &item, enum_mark_columns mark_used_columns,
List<Item> *sum_func_list, bool allow_sum_func);
bool fill_record(THD *thd, Field **field, List<Item> &values,
bool ignore_errors);
Field *
find_field_in_tables(THD *thd, Item_ident *item,
TABLE_LIST *first_table, TABLE_LIST *last_table,
Item **ref, find_item_error_report_type report_error,
bool check_privileges, bool register_tree_change);
Field *
find_field_in_table_ref(THD *thd, TABLE_LIST *table_list,
const char *name, uint length,
const char *item_name, const char *db_name,
const char *table_name, Item **ref,
bool check_privileges, bool allow_rowid,
uint *cached_field_index_ptr,
bool register_tree_change, TABLE_LIST **actual_table);
Field *
find_field_in_table(THD *thd, TABLE *table, const char *name, uint length,
bool allow_rowid, uint *cached_field_index_ptr);
Field *
find_field_in_table_sef(TABLE *table, const char *name);
Item ** find_item_in_list(Item *item, List<Item> &items, uint *counter,
find_item_error_report_type report_error,
enum_resolution_type *resolution);
bool setup_tables(THD *thd, Name_resolution_context *context,
List<TABLE_LIST> *from_clause, TABLE_LIST *tables,
TABLE_LIST **leaves, bool select_insert);
bool setup_tables_and_check_access(THD *thd,
Name_resolution_context *context,
List<TABLE_LIST> *from_clause,
TABLE_LIST *tables,
TABLE_LIST **leaves,
bool select_insert,
ulong want_access_first,
ulong want_access);
bool wait_while_table_is_used(THD *thd, TABLE *table,
enum ha_extra_function function);
void unlink_open_table(THD *thd, TABLE *find, bool unlock);
void drop_open_table(THD *thd, TABLE *table, const char *db_name,
const char *table_name);
void close_all_tables_for_name(THD *thd, TABLE_SHARE *share,
bool remove_from_locked_tables);
void update_non_unique_table_error(TABLE_LIST *update,
const char *operation,
TABLE_LIST *duplicate);
int setup_conds(THD *thd, TABLE_LIST *tables, TABLE_LIST *leaves,
COND **conds);
int setup_ftfuncs(SELECT_LEX* select);
int init_ftfuncs(THD *thd, SELECT_LEX* select, bool no_order);
bool lock_table_names(THD *thd, TABLE_LIST *table_list,
TABLE_LIST *table_list_end, ulong lock_wait_timeout,
uint flags);
bool open_tables(THD *thd, TABLE_LIST **tables, uint *counter, uint flags,
Prelocking_strategy *prelocking_strategy);
/* open_and_lock_tables with optional derived handling */
bool open_and_lock_tables(THD *thd, TABLE_LIST *tables,
bool derived, uint flags,
Prelocking_strategy *prelocking_strategy);
int open_and_lock_tables_derived(THD *thd, TABLE_LIST *tables, bool derived);
/* simple open_and_lock_tables without derived handling for single table */
TABLE *open_n_lock_single_table(THD *thd, TABLE_LIST *table_l,
thr_lock_type lock_type, uint flags);
bool open_normal_and_derived_tables(THD *thd, TABLE_LIST *tables, uint flags);
bool lock_tables(THD *thd, TABLE_LIST *tables, uint counter, uint flags);
int abort_and_upgrade_lock_and_close_table(ALTER_PARTITION_PARAM_TYPE *lpt);
int decide_logging_format(THD *thd, TABLE_LIST *tables);
void free_io_cache(TABLE *entry);
void intern_close_table(TABLE *entry);
bool close_thread_table(THD *thd, TABLE **table_ptr);
void close_temporary_tables(THD *thd);
TABLE_LIST *unique_table(THD *thd, TABLE_LIST *table, TABLE_LIST *table_list,
bool check_alias);
int drop_temporary_table(THD *thd, TABLE_LIST *table_list);
void close_temporary_table(THD *thd, TABLE *table, bool free_share,
bool delete_table);
void close_temporary(TABLE *table, bool free_share, bool delete_table);
bool rename_temporary_table(THD* thd, TABLE *table, const char *new_db,
const char *table_name);
void mysql_wait_completed_table(ALTER_PARTITION_PARAM_TYPE *lpt, TABLE *my_table);
void remove_db_from_cache(const char *db);
bool is_equal(const LEX_STRING *a, const LEX_STRING *b);
/* Functions to work with system tables. */
bool open_system_tables_for_read(THD *thd, TABLE_LIST *table_list,
Open_tables_backup *backup);
void close_system_tables(THD *thd, Open_tables_backup *backup);
void close_mysql_tables(THD *thd);
TABLE *open_system_table_for_update(THD *thd, TABLE_LIST *one_table);
TABLE *open_log_table(THD *thd, TABLE_LIST *one_table, Open_tables_backup *backup);
void close_log_table(THD *thd, Open_tables_backup *backup);
TABLE *open_performance_schema_table(THD *thd, TABLE_LIST *one_table,
Open_tables_state *backup);
void close_performance_schema_table(THD *thd, Open_tables_state *backup);
bool close_cached_tables(THD *thd, TABLE_LIST *tables, bool have_lock,
bool wait_for_refresh, ulong timeout);
bool close_cached_connection_tables(THD *thd, bool wait_for_refresh,
LEX_STRING *connect_string,
bool have_lock = FALSE);
void close_all_tables_for_name(THD *thd, TABLE_SHARE *share,
bool remove_from_locked_tables);
OPEN_TABLE_LIST *list_open_tables(THD *thd, const char *db, const char *wild);
bool remove_table_from_cache(THD *thd, const char *db, const char *table,
uint flags);
void tdc_remove_table(THD *thd, enum_tdc_remove_table_type remove_type,
const char *db, const char *table_name);
bool tdc_open_view(THD *thd, TABLE_LIST *table_list, const char *alias,
char *cache_key, uint cache_key_length,
MEM_ROOT *mem_root, uint flags);
void tdc_flush_unused_tables();
TABLE *find_table_for_mdl_upgrade(TABLE *list, const char *db,
const char *table_name,
bool no_error);
void mark_tmp_table_for_reuse(TABLE *table);
bool check_if_table_exists(THD *thd, TABLE_LIST *table, bool *exists);
extern uint table_cache_count;
extern TABLE *unused_tables;
extern Item **not_found_item;
extern Field *not_found_field;
extern Field *view_ref_found;
extern HASH open_cache;
extern HASH table_def_cache;
/**
clean/setup table fields and map.
@param table TABLE structure pointer (which should be setup)
@param table_list TABLE_LIST structure pointer (owner of TABLE)
@param tablenr table number
*/
inline void setup_table_map(TABLE *table, TABLE_LIST *table_list, uint tablenr)
{
table->used_fields= 0;
table->const_table= 0;
table->null_row= 0;
table->status= STATUS_NO_RECORD;
table->maybe_null= table_list->outer_join;
TABLE_LIST *embedding= table_list->embedding;
while (!table->maybe_null && embedding)
{
table->maybe_null= embedding->outer_join;
embedding= embedding->embedding;
}
table->tablenr= tablenr;
table->map= (table_map) 1 << tablenr;
table->force_index= table_list->force_index;
table->force_index_order= table->force_index_group= 0;
table->covering_keys= table->s->keys_for_keyread;
table->merge_keys.clear_all();
}
inline TABLE_LIST *find_table_in_global_list(TABLE_LIST *table,
const char *db_name,
const char *table_name)
{
return find_table_in_list(table, &TABLE_LIST::next_global,
db_name, table_name);
}
inline TABLE_LIST *find_table_in_local_list(TABLE_LIST *table,
const char *db_name,
const char *table_name)
{
return find_table_in_list(table, &TABLE_LIST::next_local,
db_name, table_name);
}
inline bool setup_fields_with_no_wrap(THD *thd, Item **ref_pointer_array,
List<Item> &item,
enum_mark_columns mark_used_columns,
List<Item> *sum_func_list,
bool allow_sum_func)
{
bool res;
thd->lex->select_lex.no_wrap_view_item= TRUE;
res= setup_fields(thd, ref_pointer_array, item, mark_used_columns,
sum_func_list, allow_sum_func);
thd->lex->select_lex.no_wrap_view_item= FALSE;
return res;
}
/**
An abstract class for a strategy specifying how the prelocking
algorithm should extend the prelocking set while processing
already existing elements in the set.
*/
class Prelocking_strategy
{
public:
virtual ~Prelocking_strategy() { }
virtual bool handle_routine(THD *thd, Query_tables_list *prelocking_ctx,
Sroutine_hash_entry *rt, sp_head *sp,
bool *need_prelocking) = 0;
virtual bool handle_table(THD *thd, Query_tables_list *prelocking_ctx,
TABLE_LIST *table_list, bool *need_prelocking) = 0;
virtual bool handle_view(THD *thd, Query_tables_list *prelocking_ctx,
TABLE_LIST *table_list, bool *need_prelocking)= 0;
};
/**
A Strategy for prelocking algorithm suitable for DML statements.
Ensures that all tables used by all statement's SF/SP/triggers and
required for foreign key checks are prelocked and SF/SPs used are
cached.
*/
class DML_prelocking_strategy : public Prelocking_strategy
{
public:
virtual bool handle_routine(THD *thd, Query_tables_list *prelocking_ctx,
Sroutine_hash_entry *rt, sp_head *sp,
bool *need_prelocking);
virtual bool handle_table(THD *thd, Query_tables_list *prelocking_ctx,
TABLE_LIST *table_list, bool *need_prelocking);
virtual bool handle_view(THD *thd, Query_tables_list *prelocking_ctx,
TABLE_LIST *table_list, bool *need_prelocking);
};
/**
A strategy for prelocking algorithm to be used for LOCK TABLES
statement.
*/
class Lock_tables_prelocking_strategy : public DML_prelocking_strategy
{
virtual bool handle_table(THD *thd, Query_tables_list *prelocking_ctx,
TABLE_LIST *table_list, bool *need_prelocking);
};
/**
Strategy for prelocking algorithm to be used for ALTER TABLE statements.
Unlike DML or LOCK TABLES strategy, it doesn't
prelock triggers, views or stored routines, since they are not
used during ALTER.
*/
class Alter_table_prelocking_strategy : public Prelocking_strategy
{
public:
Alter_table_prelocking_strategy(Alter_info *alter_info)
: m_alter_info(alter_info)
{}
virtual bool handle_routine(THD *thd, Query_tables_list *prelocking_ctx,
Sroutine_hash_entry *rt, sp_head *sp,
bool *need_prelocking);
virtual bool handle_table(THD *thd, Query_tables_list *prelocking_ctx,
TABLE_LIST *table_list, bool *need_prelocking);
virtual bool handle_view(THD *thd, Query_tables_list *prelocking_ctx,
TABLE_LIST *table_list, bool *need_prelocking);
private:
Alter_info *m_alter_info;
};
inline bool
open_tables(THD *thd, TABLE_LIST **tables, uint *counter, uint flags)
{
DML_prelocking_strategy prelocking_strategy;
return open_tables(thd, tables, counter, flags, &prelocking_strategy);
}
/* open_and_lock_tables with derived handling */
inline bool open_and_lock_tables(THD *thd, TABLE_LIST *tables,
bool derived, uint flags)
{
DML_prelocking_strategy prelocking_strategy;
return open_and_lock_tables(thd, tables, derived, flags,
&prelocking_strategy);
}
/**
A context of open_tables() function, used to recover
from a failed open_table() or open_routine() attempt.
*/
class Open_table_context
{
public:
enum enum_open_table_action
{
OT_NO_ACTION= 0,
OT_CONFLICT,
OT_REOPEN_TABLES,
OT_DISCOVER,
OT_REPAIR
};
Open_table_context(THD *thd, uint flags);
bool recover_from_failed_open(THD *thd);
bool request_backoff_action(enum_open_table_action action_arg,
TABLE_LIST *table);
bool can_recover_from_failed_open() const
{ return m_action != OT_NO_ACTION; }
/**
When doing a back-off, we close all tables acquired by this
statement. Return an MDL savepoint taken at the beginning of
the statement, so that we can rollback to it before waiting on
locks.
*/
MDL_ticket *start_of_statement_svp() const
{
return m_start_of_statement_svp;
}
inline ulong get_timeout() const
{
return m_timeout;
}
uint get_flags() const { return m_flags; }
private:
/**
For OT_DISCOVER and OT_REPAIR actions, the table list element for
the table which definition should be re-discovered or which
should be repaired.
*/
TABLE_LIST *m_failed_table;
MDL_ticket *m_start_of_statement_svp;
/**
Lock timeout in seconds. Initialized to LONG_TIMEOUT when opening system
tables or to the "lock_wait_timeout" system variable for regular tables.
*/
ulong m_timeout;
/* open_table() flags. */
uint m_flags;
/** Back off action. */
enum enum_open_table_action m_action;
/**
Whether we had any locks when this context was created.
If we did, they are from the previous statement of a transaction,
and we can't safely do back-off (and release them).
*/
bool m_has_locks;
};
#endif /* SQL_BASE_INCLUDED */
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