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A follow-up for 5.5 version of fix for bug#54360 "Deadlock

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DROP/ALTER/CREATE DATABASE with open HANDLER".

Remove wait_for_condition() which became unused after 
database locks were replaced with MDL scoped locks.
If one needs functionality provided by this call one can 
always use THD::enter_cond()/exit_cond() methods.

Also removed an unused include from sql_db.cc and updated 
comment describing one of used includes to reflect current
situation.
This commit is contained in:
Dmitry Lenev 2010-07-01 18:58:47 +04:00
parent 41a3dfe490
commit 8ad1aa562f
3 changed files with 1 additions and 50 deletions
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45
sql/sql_base.cc
View File

@ -2412,51 +2412,6 @@ void drop_open_table(THD *thd, TABLE *table, const char *db_name,
}
/*
Wait for condition but allow the user to send a kill to mysqld
SYNOPSIS
wait_for_condition()
thd Thread handler
mutex mutex that is currently hold that is associated with condition
Will be unlocked on return
cond Condition to wait for
*/
void wait_for_condition(THD *thd, mysql_mutex_t *mutex, mysql_cond_t *cond)
{
/* Wait until the current table is up to date */
const char *proc_info;
thd->mysys_var->current_mutex= mutex;
thd->mysys_var->current_cond= cond;
proc_info=thd->proc_info;
thd_proc_info(thd, "Waiting for table");
DBUG_ENTER("wait_for_condition");
DEBUG_SYNC(thd, "waiting_for_table");
if (!thd->killed)
mysql_cond_wait(cond, mutex);
/*
We must unlock mutex first to avoid deadlock becasue conditions are
sent to this thread by doing locks in the following order:
lock(mysys_var->mutex)
lock(mysys_var->current_mutex)
One by effect of this that one can only use wait_for_condition with
condition variables that are guranteed to not disapper (freed) even if this
mutex is unlocked
*/
mysql_mutex_unlock(mutex);
mysql_mutex_lock(&thd->mysys_var->mutex);
thd->mysys_var->current_mutex= 0;
thd->mysys_var->current_cond= 0;
thd_proc_info(thd, proc_info);
mysql_mutex_unlock(&thd->mysys_var->mutex);
DBUG_VOID_RETURN;
}
/**
Check that table exists in table definition cache, on disk
or in some storage engine.

2
sql/sql_base.h
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@ -203,8 +203,6 @@ int setup_conds(THD *thd, TABLE_LIST *tables, TABLE_LIST *leaves,
COND **conds);
int setup_ftfuncs(SELECT_LEX* select);
int init_ftfuncs(THD *thd, SELECT_LEX* select, bool no_order);
void wait_for_condition(THD *thd, mysql_mutex_t *mutex,
mysql_cond_t *cond);
bool lock_table_names(THD *thd, TABLE_LIST *table_list,
TABLE_LIST *table_list_end, ulong lock_wait_timeout,
uint flags);

4
sql/sql_db.cc
View File

@ -21,14 +21,12 @@
#include "unireg.h"
#include "sql_db.h"
#include "sql_cache.h" // query_cache_*
#include "lock.h" // wait_if_global_read_lock,
// start_waiting_global_read_lock
#include "lock.h" // lock_schema_name
#include "sql_table.h" // build_table_filename,
// filename_to_tablename
#include "sql_rename.h" // mysql_rename_tables
#include "sql_acl.h" // SELECT_ACL, DB_ACLS,
// acl_get, check_grant_db
#include "sql_base.h" // wait_for_condition
#include "log_event.h" // Query_log_event
#include <mysys_err.h>
#include "sp.h"