diff options
Diffstat (limited to 'sql/mdl.h')
| -rw-r--r-- | sql/mdl.h | 43 |
1 files changed, 29 insertions, 14 deletions
diff --git a/sql/mdl.h b/sql/mdl.h index 68f24a7a0e8..a86b45e180f 100644 --- a/sql/mdl.h +++ b/sql/mdl.h @@ -212,6 +212,7 @@ public: TRIGGER, EVENT, COMMIT, + USER_LOCK, /* user level locks. */ /* This should be the last ! */ NAMESPACE_END }; @@ -492,6 +493,7 @@ public: } enum_mdl_type get_type() const { return m_type; } MDL_lock *get_lock() const { return m_lock; } + MDL_key *get_key() const; void downgrade_exclusive_lock(enum_mdl_type type); bool has_stronger_or_equal_type(enum_mdl_type type) const; @@ -653,6 +655,7 @@ public: bool is_lock_owner(MDL_key::enum_mdl_namespace mdl_namespace, const char *db, const char *name, enum_mdl_type mdl_type); + unsigned long get_lock_owner(MDL_key *mdl_key); bool has_lock(const MDL_savepoint &mdl_savepoint, MDL_ticket *mdl_ticket); @@ -721,9 +724,9 @@ private: Lists of MDL tickets: --------------------- The entire set of locks acquired by a connection can be separated - in three subsets according to their: locks released at the end of - statement, at the end of transaction and locks are released - explicitly. + in three subsets according to their duration: locks released at + the end of statement, at the end of transaction and locks are + released explicitly. Statement and transactional locks are locks with automatic scope. They are accumulated in the course of a transaction, and released @@ -732,11 +735,12 @@ private: locks). They must not be (and never are) released manually, i.e. with release_lock() call. - Locks with explicit duration are taken for locks that span + Tickets with explicit duration are taken for locks that span multiple transactions or savepoints. These are: HANDLER SQL locks (HANDLER SQL is transaction-agnostic), LOCK TABLES locks (you can COMMIT/etc - under LOCK TABLES, and the locked tables stay locked), and + under LOCK TABLES, and the locked tables stay locked), user level + locks (GET_LOCK()/RELEASE_LOCK() functions) and locks implementing "global read lock". Statement/transactional locks are always prepended to the @@ -745,20 +749,19 @@ private: a savepoint, we start popping and releasing tickets from the front until we reach the last ticket acquired after the savepoint. - Locks with explicit duration stored are not stored in any + Locks with explicit duration are not stored in any particular order, and among each other can be split into - three sets: + four sets: - [LOCK TABLES locks] [HANDLER locks] [GLOBAL READ LOCK locks] + [LOCK TABLES locks] [USER locks] [HANDLER locks] [GLOBAL READ LOCK locks] The following is known about these sets: - * GLOBAL READ LOCK locks are always stored after LOCK TABLES - locks and after HANDLER locks. This is because one can't say - SET GLOBAL read_only=1 or FLUSH TABLES WITH READ LOCK - if one has locked tables. One can, however, LOCK TABLES - after having entered the read only mode. Note, that - subsequent LOCK TABLES statement will unlock the previous + * GLOBAL READ LOCK locks are always stored last. + This is because one can't say SET GLOBAL read_only=1 or + FLUSH TABLES WITH READ LOCK if one has locked tables. One can, + however, LOCK TABLES after having entered the read only mode. + Note, that subsequent LOCK TABLES statement will unlock the previous set of tables, but not the GRL! There are no HANDLER locks after GRL locks because SET GLOBAL read_only performs a FLUSH TABLES WITH @@ -853,6 +856,18 @@ extern bool mysql_notify_thread_having_shared_lock(THD *thd, THD *in_use, extern "C" const char* thd_enter_cond(MYSQL_THD thd, mysql_cond_t *cond, mysql_mutex_t *mutex, const char *msg); extern "C" void thd_exit_cond(MYSQL_THD thd, const char *old_msg); +extern "C" unsigned long thd_get_thread_id(const MYSQL_THD thd); + +/** + Check if a connection in question is no longer connected. + + @details + Replication apply thread is always connected. Otherwise, + does a poll on the associated socket to check if the client + is gone. +*/ +extern "C" int thd_is_connected(MYSQL_THD thd); + #ifndef DBUG_OFF extern mysql_mutex_t LOCK_open; |