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Pre-requisite patch for bug #51263 "Deadlock between

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transactional SELECT and ALTER TABLE ... REBUILD PARTITION".

The goal of this patch is to decouple type of metadata
lock acquired for table by open_tables() from type of
table-level lock to be acquired on it.

To achieve this we change approach to how we determine what
type of metadata lock should be acquired on table to be open.
Now instead of inferring it at open_tables() time from flags
and type of table-level lock we rely on that type of metadata
lock is properly set at parsing time and is not changed
further.
This commit is contained in:
Dmitry Lenev
2010-05-25 16:35:01 +04:00
parent 6ceacd4fb9
commit a3c080be7a
20 changed files with 359 additions and 227 deletions
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26
sql/sql_table.cc
View File

@ -4656,6 +4656,14 @@ static bool mysql_admin_table(THD* thd, TABLE_LIST* tables,
strxmov(table_name, db, ".", table->table_name, NullS);
thd->open_options|= extra_open_options;
table->lock_type= lock_type;
/*
To make code safe for re-execution we need to reset type of MDL
request as code below may change it.
To allow concurrent execution of read-only operations we acquire
weak metadata lock for them.
*/
table->mdl_request.set_type((lock_type >= TL_WRITE_ALLOW_READ) ?
MDL_SHARED_NO_READ_WRITE : MDL_SHARED_READ);
/* open only one table from local list of command */
{
TABLE_LIST *save_next_global, *save_next_local;
@ -4677,8 +4685,7 @@ static bool mysql_admin_table(THD* thd, TABLE_LIST* tables,
if (view_operator_func == NULL)
table->required_type=FRMTYPE_TABLE;
open_error= open_and_lock_tables(thd, table, TRUE,
MYSQL_OPEN_TAKE_UPGRADABLE_MDL);
open_error= open_and_lock_tables(thd, table, TRUE, 0);
thd->no_warnings_for_error= 0;
table->next_global= save_next_global;
table->next_local= save_next_local;
@ -5024,6 +5031,7 @@ send_result_message:
/* Clear the ticket released in close_thread_tables(). */
table->mdl_request.ticket= NULL;
DEBUG_SYNC(thd, "ha_admin_open_ltable");
table->mdl_request.set_type(MDL_SHARED_WRITE);
if ((table->table= open_ltable(thd, table, lock_type, 0)))
{
result_code= table->table->file->ha_analyze(thd, check_opt);
@ -5461,6 +5469,7 @@ mysql_discard_or_import_tablespace(THD *thd,
not complain when we lock the table
*/
thd->tablespace_op= TRUE;
table_list->mdl_request.set_type(MDL_SHARED_WRITE);
if (!(table=open_ltable(thd, table_list, TL_WRITE, 0)))
{
thd->tablespace_op=FALSE;
@ -6568,6 +6577,12 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
if (thd->global_read_lock.wait_if_global_read_lock(thd, FALSE, TRUE))
DBUG_RETURN(TRUE);
/*
TODO/FIXME: Get rid of this code branch if possible. To add insult
to injury it breaks locking protocol.
*/
table_list->mdl_request.set_type(MDL_EXCLUSIVE);
if (lock_table_names(thd, table_list))
{
error= 1;
@ -6608,8 +6623,7 @@ view_err:
Alter_table_prelocking_strategy alter_prelocking_strategy(alter_info);
error= open_and_lock_tables(thd, table_list, FALSE,
MYSQL_OPEN_TAKE_UPGRADABLE_MDL,
error= open_and_lock_tables(thd, table_list, FALSE, 0,
&alter_prelocking_strategy);
if (error)
@ -7904,6 +7918,10 @@ bool mysql_recreate_table(THD *thd, TABLE_LIST *table_list)
table_list->table= NULL;
/* Same applies to MDL ticket. */
table_list->mdl_request.ticket= NULL;
/* Set lock type which is appropriate for ALTER TABLE. */
table_list->lock_type= TL_WRITE_ALLOW_READ;
/* Same applies to MDL request. */
table_list->mdl_request.set_type(MDL_SHARED_NO_WRITE);
bzero((char*) &create_info, sizeof(create_info));
create_info.row_type=ROW_TYPE_NOT_USED;