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MDEV-15135 - Make LOCK_show_status rwlock, to enable parallelism of

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fill_status.

Also, remove LOCK_status around calc_sum_of_all_status()

Also, rename LOCK_show_status into LOCK_all_status_vars.
This reflects the variable the lock protects.
This commit is contained in:
Vladislav Vaintroub
2019-01-24 19:26:34 +01:00
committed by Sergey Vojtovich
parent 8b4fcc434d
commit c2318291be
5 changed files with 20 additions and 21 deletions
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15
sql/sql_show.cc
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@ -3383,7 +3383,7 @@ int add_status_vars(SHOW_VAR *list)
{
int res= 0;
if (status_vars_inited)
mysql_mutex_lock(&LOCK_show_status);
mysql_rwlock_wrlock(&LOCK_all_status_vars);
if (!all_status_vars.buffer && // array is not allocated yet - do it now
my_init_dynamic_array(&all_status_vars, sizeof(SHOW_VAR), 250, 50, MYF(0)))
{
@ -3398,7 +3398,7 @@ int add_status_vars(SHOW_VAR *list)
sort_dynamic(&all_status_vars, show_var_cmp);
err:
if (status_vars_inited)
mysql_mutex_unlock(&LOCK_show_status);
mysql_rwlock_unlock(&LOCK_all_status_vars);
return res;
}
@ -3460,7 +3460,7 @@ void remove_status_vars(SHOW_VAR *list)
{
if (status_vars_inited)
{
mysql_mutex_lock(&LOCK_show_status);
mysql_rwlock_wrlock(&LOCK_all_status_vars);
SHOW_VAR *all= dynamic_element(&all_status_vars, 0, SHOW_VAR *);
for (; list->name; list++)
@ -3481,7 +3481,7 @@ void remove_status_vars(SHOW_VAR *list)
}
}
shrink_var_array(&all_status_vars);
mysql_mutex_unlock(&LOCK_show_status);
mysql_rwlock_unlock(&LOCK_all_status_vars);
}
else
{
@ -7836,18 +7836,15 @@ int fill_status(THD *thd, TABLE_LIST *tables, COND *cond)
if (scope == OPT_GLOBAL)
{
/* We only hold LOCK_status for summary status vars */
mysql_mutex_lock(&LOCK_status);
calc_sum_of_all_status(&tmp);
mysql_mutex_unlock(&LOCK_status);
}
mysql_mutex_lock(&LOCK_show_status);
mysql_rwlock_rdlock(&LOCK_all_status_vars);
res= show_status_array(thd, wild,
(SHOW_VAR *)all_status_vars.buffer,
scope, tmp1, "", tables->table,
upper_case_names, partial_cond);
mysql_mutex_unlock(&LOCK_show_status);
mysql_rwlock_unlock(&LOCK_all_status_vars);
DBUG_RETURN(res);
}