#At file:///home/dlenev/src/bzr/mysql-6.0-3726-w3/
2666 Dmitry Lenev 2008-06-10
WL#3726 "DDL locking for all metadata objects".
After review fixes in progress.
modified:
sql/mdl.cc
sql/mdl.h
sql/sql_base.cc
sql/sql_show.cc
per-file comments:
sql/mdl.cc
Changed mdl_acquire_shared_lock() signature to accept MDL_CONTEXT
as one of arguments as described in specification.
sql/mdl.h
Changed mdl_acquire_shared_lock() signature to accept MDL_CONTEXT
as one of arguments as described in specification.
sql/sql_base.cc
Changed mdl_acquire_shared_lock() signature to accept MDL_CONTEXT
as one of arguments as described in specification.
Renamed handle_failed_open_table_attempt() to
recover_from_failed_open_table_attempt() as suggested by review.
Added comment clarifying why we need to check TABLE::db_stat
while looking at TABLE instances open by other threads.
sql/sql_show.cc
Changed mdl_acquire_shared_lock() signature to accept MDL_CONTEXT
as one of arguments as described in specification.
=== modified file 'sql/mdl.cc'
--- a/sql/mdl.cc 2008-06-06 10:28:58 +0000
+++ b/sql/mdl.cc 2008-06-10 14:01:56 +0000
@@ -611,6 +611,7 @@ static bool can_grant_lock(MDL_LOCK *loc
This function must be called after the lock is added to a context.
+ @param context [in] Context containing request for lock
@param lock_data [in] Lock request object for lock to be acquired
@param retry [out] Indicates that conflicting lock exists and another
attempt should be made after releasing all current
@@ -622,16 +623,19 @@ static bool can_grant_lock(MDL_LOCK *loc
In the latter case "retry" parameter is set to TRUE.
*/
-bool mdl_acquire_shared_lock(MDL_LOCK_DATA *lock_data, bool *retry)
+bool mdl_acquire_shared_lock(MDL_CONTEXT *context, MDL_LOCK_DATA *lock_data,
+ bool *retry)
{
MDL_LOCK *lock;
*retry= FALSE;
DBUG_ASSERT(is_shared(lock_data) && lock_data->state == MDL_PENDING);
+ DBUG_ASSERT(lock_data->ctx == context);
+
safe_mutex_assert_not_owner(&LOCK_open);
- if (lock_data->ctx->has_global_shared_lock &&
+ if (context->has_global_shared_lock &&
lock_data->type == MDL_SHARED_UPGRADABLE)
{
my_error(ER_CANT_UPDATE_WITH_READLOCK, MYF(0));
=== modified file 'sql/mdl.h'
--- a/sql/mdl.h 2008-06-06 10:28:58 +0000
+++ b/sql/mdl.h 2008-06-10 14:01:56 +0000
@@ -164,7 +164,8 @@ inline void mdl_set_lock_type(MDL_LOCK_D
lock_data->type= lock_type;
}
-bool mdl_acquire_shared_lock(MDL_LOCK_DATA *lock_data, bool *retry);
+bool mdl_acquire_shared_lock(MDL_CONTEXT *context, MDL_LOCK_DATA *lock_data,
+ bool *retry);
bool mdl_acquire_exclusive_locks(MDL_CONTEXT *context);
bool mdl_upgrade_shared_lock_to_exclusive(MDL_CONTEXT *context,
MDL_LOCK_DATA *lock_data);
=== modified file 'sql/sql_base.cc'
--- a/sql/sql_base.cc 2008-06-08 18:13:58 +0000
+++ b/sql/sql_base.cc 2008-06-10 14:01:56 +0000
@@ -2792,7 +2792,7 @@ TABLE *open_table(THD *thd, TABLE_LIST *
if (flags & MYSQL_LOCK_IGNORE_FLUSH)
mdl_set_lock_type(mdl_lock_data, MDL_SHARED_HIGH_PRIO);
- if (mdl_acquire_shared_lock(mdl_lock_data, &retry))
+ if (mdl_acquire_shared_lock(&thd->mdl_context, mdl_lock_data, &retry))
{
if (retry)
*action= OT_BACK_OFF_AND_RETRY;
@@ -3990,18 +3990,21 @@ end_with_lock_open:
/**
- Handle failed attempt ot open table by performing requested action.
+ Recover from failed attempt ot open table by performing requested action.
@param thd Thread context
@param table Table list element for table that caused problem
@param action Type of action requested by failed open_table() call
+ @pre This function should be called only with "action" != OT_NO_ACTION.
+
@retval FALSE - Success. One should try to open tables once again.
@retval TRUE - Error
*/
-static bool handle_failed_open_table_attempt(THD *thd, TABLE_LIST *table,
- enum_open_table_action action)
+static bool
+recover_from_failed_open_table_attempt(THD *thd, TABLE_LIST *table,
+ enum_open_table_action action)
{
bool result= FALSE;
@@ -4635,7 +4638,7 @@ int open_tables(THD *thd, TABLE_LIST **s
TABLE_LIST element. Altough currently this assumption is valid
it may change in future.
*/
- if (handle_failed_open_table_attempt(thd, tables, action))
+ if (recover_from_failed_open_table_attempt(thd, tables, action))
{
result= -1;
goto err;
@@ -4910,7 +4913,7 @@ retry:
might have been acquired successfully.
*/
close_thread_tables(thd, (action == OT_BACK_OFF_AND_RETRY));
- if (handle_failed_open_table_attempt(thd, table_list, action))
+ if (recover_from_failed_open_table_attempt(thd, table_list, action))
break;
}
@@ -8328,7 +8331,13 @@ bool notify_thread_having_shared_lock(TH
thd_table ;
thd_table= thd_table->next)
{
- /* TODO With new MDL check for db_stat is probably a legacy */
+ /*
+ Check for TABLE::db_stat is needed since in some places we call
+ handler::close() for table instance (and set TABLE::db_stat to 0)
+ and do not remove such instances from the THD::open_tables
+ for some time, during which other thread can see those instances
+ (e.g. see partitioning code).
+ */
if (thd_table->db_stat)
signalled|= mysql_lock_abort_for_thread(thd, thd_table);
}
=== modified file 'sql/sql_show.cc'
--- a/sql/sql_show.cc 2008-06-06 10:28:58 +0000
+++ b/sql/sql_show.cc 2008-06-10 14:01:56 +0000
@@ -3121,7 +3121,7 @@ static int fill_schema_table_from_frm(TH
*/
while (1)
{
- if (mdl_acquire_shared_lock(&mdl_lock_data, &retry))
+ if (mdl_acquire_shared_lock(&thd->mdl_context, &mdl_lock_data, &retry))
{
if (!retry || mdl_wait_for_locks(&thd->mdl_context))
{
| Thread |
|---|
| • bzr commit into mysql-6.0 branch (dlenev:2666) WL#3726 | Dmitry Lenev | 10 Jun |
