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A 5.5 version of the fix for Bug #54360 "Deadlock DROP/ALTER/CREATE

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DATABASE with open HANDLER"

Remove LOCK_create_db, database name locks, and use metadata locks instead.
This exposes CREATE/DROP/ALTER DATABASE statements to the graph-based
deadlock detector in MDL, and paves the way for a safe, deadlock-free
implementation of RENAME DATABASE.

Database DDL statements will now take exclusive metadata locks on
the database name, while table/view/routine DDL statements take
intention exclusive locks on the database name. This prevents race
conditions between database DDL and table/view/routine DDL.
(e.g. DROP DATABASE with concurrent CREATE/ALTER/DROP TABLE)

By adding database name locks, this patch implements
WL#4450 "DDL locking: CREATE/DROP DATABASE must use database locks" and
WL#4985 "DDL locking: namespace/hierarchical locks".

The patch also changes code to use init_one_table() where appropriate.
The new lock_table_names() function requires TABLE_LIST::db_length to
be set correctly, and this is taken care of by init_one_table().

This patch also adds a simple template to help work with 
the mysys HASH data structure.

Most of the patch was written by Konstantin Osipov.
This commit is contained in:
Jon Olav Hauglid
2010-07-01 15:53:46 +02:00
parent 29e9130d60
commit 9ff272fbbd
28 changed files with 1300 additions and 652 deletions
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10
sql/sql_rename.cc
View File

@ -24,10 +24,9 @@
#include "sql_table.h" // build_table_filename
#include "sql_view.h" // mysql_frm_type, mysql_rename_view
#include "sql_trigger.h"
#include "lock.h" // wait_if_global_read_lock, lock_table_names,
// unlock_table_names,
#include "lock.h" // wait_if_global_read_lock
// start_waiting_global_read_lock
#include "sql_base.h" // tdc_remove_table
#include "sql_base.h" // tdc_remove_table, lock_table_names,
#include "sql_handler.h" // mysql_ha_rm_tables
#include "datadict.h"
@ -144,7 +143,8 @@ bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent)
}
}
if (lock_table_names(thd, table_list))
if (lock_table_names(thd, table_list, 0, thd->variables.lock_wait_timeout,
MYSQL_OPEN_SKIP_TEMPORARY))
goto err;
mysql_mutex_lock(&LOCK_open);
@ -197,7 +197,7 @@ bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent)
if (!error)
query_cache_invalidate3(thd, table_list, 0);
unlock_table_names(thd);
thd->mdl_context.release_transactional_locks();
err:
thd->global_read_lock.start_waiting_global_read_lock(thd);