A set of changes aiming to make the Event Scheduler more user-friendly

when there are no up-to-date system tables to support it:
 - initialize the scheduler before reporting "Ready for connections".
   This ensures that warnings, if any, are printed before "Ready for
   connections", and this message is not mangled.
 - do not abort the scheduler if there are no system tables
 - check the tables once at start up, remember the status and disable
   the scheduler if the tables are not up to date.
   If one attempts to use the scheduler with bad tables,
   issue an error message.
 - clean up the behaviour of the module under LOCK TABLES and pre-locking
   mode
 - make sure implicit commit of Events DDL works as expected.
 - add more tests


Collateral clean ups in the events code.

This patch fixes Bug#23631 Events: SHOW VARIABLES doesn't work 
when mysql.event is damaged

1 files changed, 7 insertions, 18 deletions

diff --git a/sql/event_scheduler.h b/sql/event_scheduler.h
index 74d53c4f63d..70635196745 100644
--- a/sql/event_scheduler.h
+++ b/sql/event_scheduler.h
@@ -15,7 +15,8 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
-/*
+/**
+  @file
   This file is internal to Events module. Please do not include it directly.
   All public declarations of Events module are in events.h and
   event_data_objects.h.
@@ -41,10 +42,9 @@ class Event_worker_thread
 {
 public:
   static void
-  init(Events *events, Event_db_repository *db_repo)
+  init(Event_db_repository *db_repository_arg)
   {
-    db_repository= db_repo;
-    events_facade= events;
+    db_repository= db_repository_arg;
   }
 
   void
@@ -55,15 +55,15 @@ private:
   print_warnings(THD *thd, Event_job_data *et);
 
   static Event_db_repository *db_repository;
-  static Events *events_facade;
 };
 
 
 class Event_scheduler
 {
 public:
-  Event_scheduler():state(UNINITIALIZED){}
-  ~Event_scheduler(){}
+  Event_scheduler(Event_queue *event_queue_arg);
+  ~Event_scheduler();
+
 
   /* State changing methods follow */
 
@@ -80,17 +80,6 @@ public:
   bool
   run(THD *thd);
 
-  void
-  init_scheduler(Event_queue *queue);
-
-  void
-  deinit_scheduler();
-
-  void
-  init_mutexes();
-
-  void
-  deinit_mutexes();
 
   /* Information retrieving methods follow */
   bool