MDEV-18661 loading the audit plugin causes performance regression.

Plugin fixed to not lock the LOCK_operations when not active.
Server fixed to lock the LOCK_plugin less - do it once per
thread and then only if a plugin was installed/uninstalled.

1 files changed, 16 insertions, 0 deletions

diff --git a/sql/sql_audit.cc b/sql/sql_audit.cc
index dd98e3cf9b1..cee0ac2287c 100644
--- a/sql/sql_audit.cc
+++ b/sql/sql_audit.cc
@@ -212,6 +212,7 @@ void mysql_audit_acquire_plugins(THD *thd, ulong *event_class_mask)
   {
     plugin_foreach(thd, acquire_plugins, MYSQL_AUDIT_PLUGIN, event_class_mask);
     add_audit_mask(thd->audit_class_mask, event_class_mask);
+    thd->audit_plugin_version= global_plugin_version;
   }
   DBUG_VOID_RETURN;
 }
@@ -242,6 +243,20 @@ void mysql_audit_notify(THD *thd, uint event_class, uint event_subtype, ...)
 
 
 /**
+  Check if there were changes in the state of plugins
+  so we need to do the mysql_audit_release asap.
+
+  @param[in] thd
+
+*/
+
+my_bool mysql_audit_release_required(THD *thd)
+{
+  return thd && (thd->audit_plugin_version != global_plugin_version);
+}
+
+
+/**
   Release any resources associated with the current thd.
   
   @param[in] thd
@@ -276,6 +291,7 @@ void mysql_audit_release(THD *thd)
   /* Reset the state of thread values */
   reset_dynamic(&thd->audit_class_plugins);
   bzero(thd->audit_class_mask, sizeof(thd->audit_class_mask));
+  thd->audit_plugin_version= -1;
 }