mariadb/sql/lock.h
Jon Olav Hauglid 41a3dfe490 A 5.5 version of the fix for Bug #54360 "Deadlock DROP/ALTER/CREATE
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.
2010-07-01 15:53:46 +02:00

70 lines
2.8 KiB
C++

#ifndef LOCK_INCLUDED
#define LOCK_INCLUDED
#include "thr_lock.h" /* thr_lock_type */
// Forward declarations
struct TABLE;
struct TABLE_LIST;
class THD;
typedef struct st_mysql_lock MYSQL_LOCK;
/* mysql_lock_tables() and open_table() flags bits */
#define MYSQL_OPEN_IGNORE_GLOBAL_READ_LOCK 0x0001
#define MYSQL_OPEN_IGNORE_FLUSH 0x0002
#define MYSQL_OPEN_TEMPORARY_ONLY 0x0004
#define MYSQL_LOCK_IGNORE_GLOBAL_READ_ONLY 0x0008
#define MYSQL_LOCK_LOG_TABLE 0x0010
/**
Do not try to acquire a metadata lock on the table: we
already have one.
*/
#define MYSQL_OPEN_HAS_MDL_LOCK 0x0020
/**
If in locked tables mode, ignore the locked tables and get
a new instance of the table.
*/
#define MYSQL_OPEN_GET_NEW_TABLE 0x0040
/** Don't look up the table in the list of temporary tables. */
#define MYSQL_OPEN_SKIP_TEMPORARY 0x0080
/** Fail instead of waiting when conficting metadata lock is discovered. */
#define MYSQL_OPEN_FAIL_ON_MDL_CONFLICT 0x0100
/** Open tables using MDL_SHARED lock instead of one specified in parser. */
#define MYSQL_OPEN_FORCE_SHARED_MDL 0x0200
/**
Open tables using MDL_SHARED_HIGH_PRIO lock instead of one specified
in parser.
*/
#define MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL 0x0400
/**
When opening or locking the table, use the maximum timeout
(LONG_TIMEOUT = 1 year) rather than the user-supplied timeout value.
*/
#define MYSQL_LOCK_IGNORE_TIMEOUT 0x0800
/** Please refer to the internals manual. */
#define MYSQL_OPEN_REOPEN (MYSQL_OPEN_IGNORE_FLUSH |\
MYSQL_OPEN_IGNORE_GLOBAL_READ_LOCK |\
MYSQL_LOCK_IGNORE_GLOBAL_READ_ONLY |\
MYSQL_LOCK_IGNORE_TIMEOUT |\
MYSQL_OPEN_GET_NEW_TABLE |\
MYSQL_OPEN_SKIP_TEMPORARY |\
MYSQL_OPEN_HAS_MDL_LOCK)
MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **table, uint count, uint flags);
void mysql_unlock_tables(THD *thd, MYSQL_LOCK *sql_lock);
void mysql_unlock_read_tables(THD *thd, MYSQL_LOCK *sql_lock);
void mysql_unlock_some_tables(THD *thd, TABLE **table,uint count);
void mysql_lock_remove(THD *thd, MYSQL_LOCK *locked,TABLE *table);
void mysql_lock_abort(THD *thd, TABLE *table, bool upgrade_lock);
bool mysql_lock_abort_for_thread(THD *thd, TABLE *table);
MYSQL_LOCK *mysql_lock_merge(MYSQL_LOCK *a,MYSQL_LOCK *b);
void broadcast_refresh(void);
/* Lock based on name */
bool lock_schema_name(THD *thd, const char *db);
/* Lock based on stored routine name */
bool lock_routine_name(THD *thd, bool is_function, const char *db,
const char *name);
#endif /* LOCK_INCLUDED */