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----------------------------------------------------------
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.
This commit is contained in:
Konstantin Osipov
2009-12-08 12:57:07 +03:00
parent 4a8a1c568d
commit a66a2608ae
30 changed files with 566 additions and 733 deletions
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53
sql/sql_class.h
View File

@ -1180,6 +1180,49 @@ private:
Internal_error_handler *m_err_handler;
};
/**
A context of open_tables() function, used to recover
from a failed open_table() attempt.
Implemented in sql_base.cc.
*/
class Open_table_context
{
public:
enum enum_open_table_action
{
OT_NO_ACTION= 0,
OT_WAIT,
OT_DISCOVER,
OT_REPAIR
};
Open_table_context(THD *thd);
bool recover_from_failed_open_table_attempt(THD *thd, TABLE_LIST *tables);
bool request_backoff_action(enum_open_table_action action_arg);
void add_request(MDL_request *request)
{ m_mdl_requests.push_front(request); }
bool can_recover_from_failed_open_table() const
{ return m_action != OT_NO_ACTION; }
bool can_deadlock() const { return m_can_deadlock; }
private:
/** List of requests for all locks taken so far. Used for waiting on locks. */
MDL_request_list m_mdl_requests;
/** 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_can_deadlock;
};
/**
Tables that were locked with LOCK TABLES statement.
@ -1236,7 +1279,6 @@ public:
}
bool init_locked_tables(THD *thd);
TABLE_LIST *locked_tables() { return m_locked_tables; }
MEM_ROOT *locked_tables_root() { return &m_locked_tables_root; }
void unlink_from_list(THD *thd, TABLE_LIST *table_list,
bool remove_from_locked_tables);
void unlink_all_closed_tables(THD *thd,
@ -1895,15 +1937,6 @@ public:
/* Debug Sync facility. See debug_sync.cc. */
struct st_debug_sync_control *debug_sync_control;
#endif /* defined(ENABLED_DEBUG_SYNC) */
/**
Points to the memory root of Locked_tables_list if
we're locking the tables for LOCK TABLES. Otherwise is NULL.
This is necessary to ensure that metadata locks allocated for
tables used in triggers will persist after statement end.
*/
MEM_ROOT *locked_tables_root;
THD();
~THD();