diff options
Diffstat (limited to 'sql/lock.cc')
| -rw-r--r-- | sql/lock.cc | 67 |
1 files changed, 28 insertions, 39 deletions
diff --git a/sql/lock.cc b/sql/lock.cc index de0f39018f7..dcee018276f 100644 --- a/sql/lock.cc +++ b/sql/lock.cc @@ -747,62 +747,48 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count, } -/***************************************************************************** - Lock table based on the name. - This is used when we need total access to a closed, not open table -*****************************************************************************/ - /** - Obtain exclusive metadata locks on the list of tables. + Obtain an exclusive metadata lock on a schema name. - @param thd Thread handle - @param table_list List of tables to lock + @param thd Thread handle. + @param db The database name. - @note This function assumes that no metadata locks were acquired - before calling it. Also it cannot be called while holding - LOCK_open mutex. Both these invariants are enforced by asserts - in MDL_context::acquire_locks(). - @note Initialization of MDL_request members of TABLE_LIST elements - is a responsibility of the caller. + This function cannot be called while holding LOCK_open mutex. + To avoid deadlocks, we do not try to obtain exclusive metadata + locks in LOCK TABLES mode, since in this mode there may be + other metadata locks already taken by the current connection, + and we must not wait for MDL locks while holding locks. - @retval FALSE Success. - @retval TRUE Failure (OOM or thread was killed). + @retval FALSE Success. + @retval TRUE Failure: we're in LOCK TABLES mode, or out of memory, + or this connection was killed. */ -bool lock_table_names(THD *thd, TABLE_LIST *table_list) +bool lock_schema_name(THD *thd, const char *db) { MDL_request_list mdl_requests; MDL_request global_request; - TABLE_LIST *lock_table; + MDL_request mdl_request; - global_request.init(MDL_key::GLOBAL, "", "", MDL_INTENTION_EXCLUSIVE); + if (thd->locked_tables_mode) + { + my_message(ER_LOCK_OR_ACTIVE_TRANSACTION, + ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0)); + return TRUE; + } - for (lock_table= table_list; lock_table; lock_table= lock_table->next_local) - mdl_requests.push_front(&lock_table->mdl_request); + global_request.init(MDL_key::GLOBAL, "", "", MDL_INTENTION_EXCLUSIVE); + mdl_request.init(MDL_key::SCHEMA, db, "", MDL_EXCLUSIVE); + mdl_requests.push_front(&mdl_request); mdl_requests.push_front(&global_request); if (thd->mdl_context.acquire_locks(&mdl_requests, thd->variables.lock_wait_timeout)) - return 1; - - return 0; -} - - -/** - Release all metadata locks previously obtained by lock_table_names(). - - @param thd Thread handle. - - @note Cannot be called while holding LOCK_open mutex. -*/ + return TRUE; -void unlock_table_names(THD *thd) -{ - DBUG_ENTER("unlock_table_names"); - thd->mdl_context.release_transactional_locks(); - DBUG_VOID_RETURN; + DEBUG_SYNC(thd, "after_wait_locked_schema_name"); + return FALSE; } @@ -837,6 +823,7 @@ bool lock_routine_name(THD *thd, bool is_function, MDL_key::PROCEDURE); MDL_request_list mdl_requests; MDL_request global_request; + MDL_request schema_request; MDL_request mdl_request; if (thd->locked_tables_mode) @@ -850,9 +837,11 @@ bool lock_routine_name(THD *thd, bool is_function, DEBUG_SYNC(thd, "before_wait_locked_pname"); global_request.init(MDL_key::GLOBAL, "", "", MDL_INTENTION_EXCLUSIVE); + schema_request.init(MDL_key::SCHEMA, db, "", MDL_INTENTION_EXCLUSIVE); mdl_request.init(mdl_type, db, name, MDL_EXCLUSIVE); mdl_requests.push_front(&mdl_request); + mdl_requests.push_front(&schema_request); mdl_requests.push_front(&global_request); if (thd->mdl_context.acquire_locks(&mdl_requests, |