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Allocate orig_list statically

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tool_list is a temporary list needed only for SET SESSION
session_track_system_variables, so allocate it on stack instead.

Sane reinit() calls.

Saves 2 new/delete per connection.

Part of MDEV-14984 - regression in connect performance
This commit is contained in:
Sergey Vojtovich 2019-03-13 13:41:18 +04:00
parent 55bdd7f7b4
commit 01e8f3c52b
1 changed files with 17 additions and 40 deletions
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57
sql/session_tracker.cc
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@ -98,8 +98,7 @@ class Session_sysvars_tracker : public State_tracker
my_hash_element(&m_registered_sysvars, i));
}
public:
vars_list() :
buffer_length(0)
vars_list(): buffer_length(0), track_all(false)
{
m_mem_flag= current_thd ? MY_THREAD_SPECIFIC : 0;
init();
@ -150,30 +149,16 @@ class Session_sysvars_tracker : public State_tracker
Two objects of vars_list type are maintained to manage
various operations.
*/
vars_list *orig_list, *tool_list;
vars_list orig_list;
public:
Session_sysvars_tracker()
{
orig_list= new (std::nothrow) vars_list();
tool_list= new (std::nothrow) vars_list();
}
~Session_sysvars_tracker()
{
if (orig_list)
delete orig_list;
if (tool_list)
delete tool_list;
}
size_t get_buffer_length()
{
return orig_list->get_buffer_length();
return orig_list.get_buffer_length();
}
bool construct_var_list(char *buf, size_t buf_len)
{
return orig_list->construct_var_list(buf, buf_len);
return orig_list.construct_var_list(buf, buf_len);
}
bool enable(THD *thd);
@ -249,7 +234,6 @@ void Session_sysvars_tracker::vars_list::reinit()
void Session_sysvars_tracker::vars_list::copy(vars_list* from, THD *thd)
{
reinit();
track_all= from->track_all;
free_hash();
buffer_length= from->buffer_length;
@ -271,10 +255,7 @@ bool Session_sysvars_tracker::vars_list::insert(const sys_var *svar)
sysvar_node_st *node;
if (!(node= (sysvar_node_st *) my_malloc(sizeof(sysvar_node_st),
MYF(MY_WME | m_mem_flag))))
{
reinit();
return true;
}
node->m_svar= (sys_var *)svar;
node->test_load= node->m_svar->test_load;
@ -285,7 +266,6 @@ bool Session_sysvars_tracker::vars_list::insert(const sys_var *svar)
if (!search((sys_var *)svar))
{
//EOF (error is already reported)
reinit();
return true;
}
}
@ -322,7 +302,6 @@ bool Session_sysvars_tracker::vars_list::parse_var_list(THD *thd,
const char separator= ',';
char *token, *lasts= NULL;
size_t rest= var_list.length;
reinit();
if (!var_list.str || var_list.length == 0)
{
@ -573,14 +552,13 @@ bool Session_sysvars_tracker::enable(THD *thd)
LEX_STRING tmp;
tmp.str= global_system_variables.session_track_system_variables;
tmp.length= safe_strlen(tmp.str);
if (tool_list->parse_var_list(thd, tmp,
true, thd->charset(), false) == true)
if (orig_list.parse_var_list(thd, tmp, true, thd->charset(), false) == true)
{
mysql_mutex_unlock(&LOCK_plugin);
orig_list.reinit();
return true;
}
mysql_mutex_unlock(&LOCK_plugin);
orig_list->copy(tool_list, thd);
m_enabled= true;
return false;
@ -593,6 +571,9 @@ bool Session_sysvars_tracker::enable(THD *thd)
Session_sysvars_tracker::vars_list::copy updating the hash in orig_list
which represents the system variables to be tracked.
We are doing via tool list because there possible errors with memory
in this case value will be unchanged.
@note This function is called from the ON_UPDATE() function of the
session_track_system_variables' sys_var class.
@ -604,15 +585,11 @@ bool Session_sysvars_tracker::enable(THD *thd)
bool Session_sysvars_tracker::update(THD *thd, set_var *var)
{
/*
We are doing via tool list because there possible errors with memory
in this case value will be unchanged.
*/
tool_list->reinit();
if (tool_list->parse_var_list(thd, var->save_result.string_value, true,
thd->charset(), true))
vars_list tool_list;
if (tool_list.parse_var_list(thd, var->save_result.string_value, true,
thd->charset(), true))
return true;
orig_list->copy(tool_list, thd);
orig_list.copy(&tool_list, thd);
return false;
}
@ -694,13 +671,13 @@ bool Session_sysvars_tracker::vars_list::store(THD *thd, String *buf)
bool Session_sysvars_tracker::store(THD *thd, String *buf)
{
if (!orig_list->is_enabled())
if (!orig_list.is_enabled())
return false;
if (orig_list->store(thd, buf))
if (orig_list.store(thd, buf))
return true;
orig_list->reset();
orig_list.reset();
return false;
}
@ -721,7 +698,7 @@ void Session_sysvars_tracker::mark_as_changed(THD *thd,
Check if the specified system variable is being tracked, if so
mark it as changed and also set the class's m_changed flag.
*/
if (orig_list->is_enabled() && (node= orig_list->insert_or_search(svar)))
if (orig_list.is_enabled() && (node= orig_list.insert_or_search(svar)))
{
node->m_changed= true;
State_tracker::mark_as_changed(thd, var);