WL#3337 (Event scheduler new architecture)

Post-review fixes. Mostly whitespace, int-to-bool return value, fixed comments


sql/Makefile.am:
  compile all submodules of Events before compiling the facade
sql/event_data_objects.cc:
  - Use initialization list
  - Clean whitespaces
  - Shorten comments
  - Fix comments
sql/event_data_objects.h:
  - Fix whitespace
sql/event_db_repository.cc:
  - Change return type from int to bool where only one error code is
    returned.
  - Don't use macros but get the maximal number of characters in a column
    from the column
  - Fix  comments
  - Make functions which has return value but it's not used - void.
sql/event_db_repository.h:
  - Methods with only one error code int -> bool return value
  - Remove declaration of fill_schema_events, a function that does not exist
sql/event_queue.cc:
  - Use initialization lists
  - Let find_n_remove_event delete the object thus making the code more robust.
    The caller could forget to destruct the object. In addition, find_n_remove_element()
    does not return a value.
  - Move check_system_tables() to class Events
  - Fix comments
sql/event_queue.h:
  - Whitespace changes
  - init_queue() should allow passing of THD
  - check_system_tables moved to class Events
  - find_n_remove_event() is now void
sql/event_scheduler.cc:
  - Initialize res before use
  - Remove end stop from message
sql/event_scheduler.h:
  Add uninitialized state. The scheduler is in it before init_scheduler()
  is called. The rationale is that otherwise state has no value before
  the call. If the system tables were damaged the scheduler won't be initialized
  but in Events::deinit() Event_scheduler::stop() will be called and this will
  touch state, generating valgrind warning at minimum.
sql/events.cc:
  - Whitespace changes
  - Fix comments
  - Make methods which have only one error code be bool instead of int
  - Create temporarily a THD to be used for the initialization of Event_queue
  - Event_queue::check_system_tables() moved to Events::check_system_tables
  - is_started() is renamed to is_execution_of_events_started()
sql/events.h:
  - Whitespace changes
  - When a method returns only one error code it should be bool, not int
  - is_started() renamed to is_execution_of_events_started()
sql/set_var.cc:
  is_started() is renamed to is_execution_of_events_started()
sql/sql_db.cc:
  The return code is not used, thus don't return anything and drop_schema_events()
  is now void.
sql/sql_yacc.yy:
  - Fix comments
  - Remove unneeded initialization which is performed in lex_init()
sql/share/errmsg.txt:
  New error message
sql/table.cc:
  - Fix comments
  - make table_check_intact() accespt const *table_def
sql/table.h:
  Make table_check_intact() accespt const *table_def

sql/event_queue.h

@@ -31,12 +31,12 @@ public:
 
   void
   init_mutexes();
-  
+
   void
   deinit_mutexes();
-  
+
   bool
-  init_queue(Event_db_repository *db_repo, Event_scheduler *sched);
+  init_queue(THD *thd, Event_db_repository *db_repo, Event_scheduler *sched);
   
   void
   deinit_queue();
@@ -56,9 +56,6 @@ public:
   void
   drop_schema_events(THD *thd, LEX_STRING schema);
 
-  void
-  check_system_tables(THD *thd);
-
   void
   recalculate_activation_times(THD *thd);
 
@@ -72,7 +69,7 @@ public:
   load_events_from_db(THD *thd);
 
 protected:
-  Event_queue_element *
+  void
   find_n_remove_event(LEX_STRING db, LEX_STRING name);
 
 
@@ -107,7 +104,7 @@ protected:
   const char* mutex_last_attempted_lock_in_func;
   bool mutex_queue_data_locked;
   bool mutex_queue_data_attempting_lock;
-  
+
   /* helper functions for working with mutexes & conditionals */
   void
   lock_data(const char *func, uint line);