Sergei, I have pushed the updates in the separate commit:
diff --git a/storage/perfschema/pfs_variable.cc
b/storage/perfschema/pfs_variable.cc
index 984b68e699b..85656532c72 100644 --- a/storage/perfschema/pfs_variable.cc +++ b/storage/perfschema/pfs_variable.cc @@ -100,6 +102,15 @@ bool PFS_system_variable_cache::init_show_var_array(enum_var_type scope, bool st
mysql_prlock_unlock(&LOCK_system_variables_hash);
+ for (uint i= 0; i < m_show_var_array.elements(); i++)
why separately, not in the loop above?
I wanted to do ti outside of LOCK_system_variables_hash, only that's why.
+ { + sys_var *var= (sys_var *)m_show_var_array.at(i).value; + if (!var) continue;
can var be NULL?
I have seen this protection elsewhere in PS code, and blindly relied on that it's important:)
See for example the loop in PFS_system_variable_cache::do_materialize_global. They only continue until the value is NULL. Do you have a clue why?
+ sys_var *prev= i == 0 ? NULL : (sys_var *)m_show_var_array.at (i-1).value;
hmm, normally this is done with
sys_var *prev= NULL;
before the loop and
prev= var;
in the loop, after plugin_lock_by_var_if_different().
Right, that'll be better. I'll rewrite.
Since it is already a separate loop, I have extracted it to the plugin_lock_by_sys_var_array function altogether. The function's meaning is now much cleaner itself. And besides there's much less conditions computed in the loop, so it's faster.
@@ -316,7 +327,27 @@ class PFS_system_variable_cache_apc: public
Apc_target::Apc_call
void call_in_target_thread() override { - (m_pfs->*m_func)(m_param); + call(m_pfs, m_func, m_param); + } +public: + static void call(PFS_system_variable_cache *pfs, Request func, uint
param)
+ { + THD *safe_thd= pfs->safe_thd(); + + if (pfs->query_scope() == OPT_SESSION)
what's the point doing apc call if the query_scope() is not OPT_SESSION? It seems like here you need a DBUG_ASSERT, and the if() should be much earlier up the stack.
I just used the same mechanism for global variables as well. I understand now it's an overkill. Will simplify!
I realized i didn't touch global variables traverse, so moving this check to an assertion was enough -- Yours truly, Nikita Malyavin