diff options
Diffstat (limited to 'sql/handler.h')
| -rw-r--r-- | sql/handler.h | 72 |
1 files changed, 31 insertions, 41 deletions
diff --git a/sql/handler.h b/sql/handler.h index 172f43b6b59..ddea6c3a34c 100644 --- a/sql/handler.h +++ b/sql/handler.h @@ -1021,6 +1021,7 @@ public: uint ref_length; FT_INFO *ft_handler; enum {NONE=0, INDEX, RND} inited; + bool locked; bool implicit_emptied; /* Can be !=0 only if HEAP */ const COND *pushed_cond; /* @@ -1051,11 +1052,13 @@ public: estimation_rows_to_insert(0), ht(ht_arg), ref(0), key_used_on_scan(MAX_KEY), active_index(MAX_KEY), ref_length(sizeof(my_off_t)), - ft_handler(0), inited(NONE), implicit_emptied(0), + ft_handler(0), inited(NONE), + locked(FALSE), implicit_emptied(0), pushed_cond(0), next_insert_id(0), insert_id_for_cur_row(0) {} virtual ~handler(void) { + DBUG_ASSERT(locked == FALSE); /* TODO: DBUG_ASSERT(inited == NONE); */ } virtual handler *clone(MEM_ROOT *mem_root); @@ -1064,44 +1067,6 @@ public: { cached_table_flags= table_flags(); } - /* - Check whether a handler allows to lock the table. - - SYNOPSIS - check_if_locking_is_allowed() - thd Handler of the thread, trying to lock the table - table Table handler to check - count Total number of tables to be locked - current Index of the current table in the list of the tables - to be locked. - system_count Pointer to the counter of system tables seen thus - far. - called_by_privileged_thread TRUE if called from a logger THD - (general_log_thd or slow_log_thd) - or by a privileged thread, which - has the right to lock log tables. - - DESCRIPTION - Check whether a handler allows to lock the table. For instance, - MyISAM does not allow to lock mysql.proc along with other tables. - This limitation stems from the fact that MyISAM does not support - row-level locking and we have to add this limitation to avoid - deadlocks. - - RETURN - TRUE Locking is allowed - FALSE Locking is not allowed. The error was thrown. - */ - virtual bool check_if_locking_is_allowed(uint sql_command, - ulong type, TABLE *table, - uint count, uint current, - uint *system_count, - bool called_by_privileged_thread) - { - return TRUE; - } - bool check_if_log_table_locking_is_allowed(uint sql_command, - ulong type, TABLE *table); int ha_open(TABLE *table, const char *name, int mode, int test_if_locked); void adjust_next_insert_id_after_explicit_value(ulonglong nr); int update_auto_increment(); @@ -1658,8 +1623,10 @@ public: /* lock_count() can be more than one if the table is a MERGE */ virtual uint lock_count(void) const { return 1; } - /* - NOTE that one can NOT rely on table->in_use in store_lock(). It may + /** + Is not invoked for non-transactional temporary tables. + + @note that one can NOT rely on table->in_use in store_lock(). It may refer to a different thread if called from mysql_lock_abort_for_thread(). */ virtual THR_LOCK_DATA **store_lock(THD *thd, @@ -1790,6 +1757,29 @@ private: overridden by the storage engine class. To call these methods, use the corresponding 'ha_*' method above. */ + + /** + Is not invoked for non-transactional temporary tables. + + Tells the storage engine that we intend to read or write data + from the table. This call is prefixed with a call to handler::store_lock() + and is invoked only for those handler instances that stored the lock. + + Calls to rnd_init/index_init are prefixed with this call. When table + IO is complete, we call external_lock(F_UNLCK). + A storage engine writer should expect that each call to + ::external_lock(F_[RD|WR]LOCK is followed by a call to + ::external_lock(F_UNLCK). If it is not, it is a bug in MySQL. + + The name and signature originate from the first implementation + in MyISAM, which would call fcntl to set/clear an advisory + lock on the data file in this method. + + @param lock_type F_RDLCK, F_WRLCK, F_UNLCK + + @return non-0 in case of failure, 0 in case of success. + When lock_type is F_UNLCK, the return value is ignored. + */ virtual int external_lock(THD *thd __attribute__((unused)), int lock_type __attribute__((unused))) { |