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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 34e409fafa
commit 41a3dfe490
28 changed files with 1300 additions and 652 deletions
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97
sql/sql_acl.cc
View File

@ -677,16 +677,15 @@ my_bool acl_reload(THD *thd)
To avoid deadlocks we should obtain table locks before
obtaining acl_cache->lock mutex.
*/
bzero((char*) tables, sizeof(tables));
tables[0].alias= tables[0].table_name= (char*) "host";
tables[1].alias= tables[1].table_name= (char*) "user";
tables[2].alias= tables[2].table_name= (char*) "db";
tables[0].db=tables[1].db=tables[2].db=(char*) "mysql";
tables[0].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("host"), "host", TL_READ);
tables[1].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("user"), "user", TL_READ);
tables[2].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("db"), "db", TL_READ);
tables[0].next_local= tables[0].next_global= tables+1;
tables[1].next_local= tables[1].next_global= tables+2;
tables[0].lock_type=tables[1].lock_type=tables[2].lock_type=TL_READ;
tables[0].open_type= tables[1].open_type= tables[2].open_type= OT_BASE_ONLY;
init_mdl_requests(tables);
if (open_and_lock_tables(thd, tables, FALSE, MYSQL_LOCK_IGNORE_TIMEOUT))
{
@ -1925,9 +1924,8 @@ static bool test_if_create_new_users(THD *thd)
{
TABLE_LIST tl;
ulong db_access;
bzero((char*) &tl,sizeof(tl));
tl.db= (char*) "mysql";
tl.table_name= (char*) "user";
tl.init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("user"), "user", TL_WRITE);
create_new_users= 1;
db_access=acl_get(sctx->host, sctx->ip,
@ -3107,20 +3105,18 @@ int mysql_table_grant(THD *thd, TABLE_LIST *table_list,
/* open the mysql.tables_priv and mysql.columns_priv tables */
bzero((char*) &tables,sizeof(tables));
tables[0].alias=tables[0].table_name= (char*) "user";
tables[1].alias=tables[1].table_name= (char*) "tables_priv";
tables[2].alias=tables[2].table_name= (char*) "columns_priv";
tables[0].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("user"), "user", TL_WRITE);
tables[1].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("tables_priv"),
"tables_priv", TL_WRITE);
tables[2].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("columns_priv"),
"columns_priv", TL_WRITE);
tables[0].next_local= tables[0].next_global= tables+1;
/* Don't open column table if we don't need it ! */
tables[1].next_local=
tables[1].next_global= ((column_priv ||
(revoke_grant &&
((rights & COL_ACLS) || columns.elements)))
? tables+2 : 0);
tables[0].lock_type=tables[1].lock_type=tables[2].lock_type=TL_WRITE;
tables[0].db=tables[1].db=tables[2].db=(char*) "mysql";
init_mdl_requests(tables);
if (column_priv || (revoke_grant && ((rights & COL_ACLS) || columns.elements)))
tables[1].next_local= tables[1].next_global= tables+2;
/*
This statement will be replicated as a statement, even when using
@ -3354,13 +3350,11 @@ bool mysql_routine_grant(THD *thd, TABLE_LIST *table_list, bool is_proc,
/* open the mysql.user and mysql.procs_priv tables */
bzero((char*) &tables,sizeof(tables));
tables[0].alias=tables[0].table_name= (char*) "user";
tables[1].alias=tables[1].table_name= (char*) "procs_priv";
tables[0].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("user"), "user", TL_WRITE);
tables[1].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("procs_priv"), "procs_priv", TL_WRITE);
tables[0].next_local= tables[0].next_global= tables+1;
tables[0].lock_type=tables[1].lock_type=TL_WRITE;
tables[0].db=tables[1].db=(char*) "mysql";
init_mdl_requests(tables);
/*
This statement will be replicated as a statement, even when using
@ -3511,13 +3505,11 @@ bool mysql_grant(THD *thd, const char *db, List <LEX_USER> &list,
}
/* open the mysql.user and mysql.db tables */
bzero((char*) &tables,sizeof(tables));
tables[0].alias=tables[0].table_name=(char*) "user";
tables[1].alias=tables[1].table_name=(char*) "db";
tables[0].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("user"), "user", TL_WRITE);
tables[1].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("db"), "db", TL_WRITE);
tables[0].next_local= tables[0].next_global= tables+1;
tables[0].lock_type=tables[1].lock_type=TL_WRITE;
tables[0].db=tables[1].db=(char*) "mysql";
init_mdl_requests(tables);
/*
This statement will be replicated as a statement, even when using
@ -3930,14 +3922,14 @@ my_bool grant_reload(THD *thd)
if (!initialized)
DBUG_RETURN(0);
bzero((char*) tables, sizeof(tables));
tables[0].alias= tables[0].table_name= (char*) "tables_priv";
tables[1].alias= tables[1].table_name= (char*) "columns_priv";
tables[0].db= tables[1].db= (char *) "mysql";
tables[0].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("tables_priv"),
"tables_priv", TL_READ);
tables[1].init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("columns_priv"),
"columns_priv", TL_READ);
tables[0].next_local= tables[0].next_global= tables+1;
tables[0].lock_type= tables[1].lock_type= TL_READ;
tables[0].open_type= tables[1].open_type= OT_BASE_ONLY;
init_mdl_requests(tables);
/*
To avoid deadlocks we should obtain table locks before
@ -5209,22 +5201,23 @@ int open_grant_tables(THD *thd, TABLE_LIST *tables)
DBUG_RETURN(-1);
}
bzero((char*) tables, GRANT_TABLES*sizeof(*tables));
tables->alias= tables->table_name= (char*) "user";
(tables+1)->alias= (tables+1)->table_name= (char*) "db";
(tables+2)->alias= (tables+2)->table_name= (char*) "tables_priv";
(tables+3)->alias= (tables+3)->table_name= (char*) "columns_priv";
(tables+4)->alias= (tables+4)->table_name= (char*) "procs_priv";
tables->init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("user"), "user", TL_WRITE);
(tables+1)->init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("db"), "db", TL_WRITE);
(tables+2)->init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("tables_priv"),
"tables_priv", TL_WRITE);
(tables+3)->init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("columns_priv"),
"columns_priv", TL_WRITE);
(tables+4)->init_one_table(C_STRING_WITH_LEN("mysql"),
C_STRING_WITH_LEN("procs_priv"),
"procs_priv", TL_WRITE);
tables->next_local= tables->next_global= tables+1;
(tables+1)->next_local= (tables+1)->next_global= tables+2;
(tables+2)->next_local= (tables+2)->next_global= tables+3;
(tables+3)->next_local= (tables+3)->next_global= tables+4;
tables->lock_type= (tables+1)->lock_type=
(tables+2)->lock_type= (tables+3)->lock_type=
(tables+4)->lock_type= TL_WRITE;
tables->db= (tables+1)->db= (tables+2)->db=
(tables+3)->db= (tables+4)->db= (char*) "mysql";
init_mdl_requests(tables);
#ifdef HAVE_REPLICATION
/*