mariadb/sql/event_scheduler.h
unknown 3c39b0d831 Fix for bug#22740 Events: Decouple Event_queue from Event_db_repository
This patch implements the idea of the bug report by making Event_queue
unaware of Event_db_repository by making a higher level class - Events,
which is aware of most of all classes, responsible for passing all data
needed for adding/updating/deleting an event to/from the queue.

Introduces few new classes :
 - Event_worker_thread
 - Event_queue_element_for_exec


sql/event_data_objects.cc:
  Introduced a new class Event_queue_element_for_exec
  According to Konstantin it should be named Event_name and hold
  only two LEX_STRINGs but `dropped` is not saved on disk and will
  require additional logic in Event_worker_thread class, after loading
  to compute whether the event should be dropped or not. It's easier
  just to pass this flag around.
  
  Removed Event_queue_element::drop(). This method was a source of a
  race condition. At the place where the event should be dropped we
  call Events::drop_event() which is the only code-flow for dropping.
  In addition, because ::drop_event() holds Events::LOCK_metadata there is
  no source of race conditions. Before this patch dropping from ::drop()
  wasn't under LOCK_metadata and races were possible.
  
  Because Events::open_event_table was removed as a method, provisionally
  events_event_db_repository was exported from events.cc till a solution is
  build where Event_queue_element does not access directly mysql.event.
sql/event_data_objects.h:
  New class Event_queue_element_for_exec added which is returned
  from Event_queue::get_top_if_time() and passed through Event_scheduler
  to Event_worker_thread. There by using the (db)name Event_job_data is
  instanciated and executed.
  
  Dropped Event_queue_element::drop()
  
  thd was moved out of Event_job_data as it is now part of
  Event_queue_element_for_exec
sql/event_queue.cc:
  Removed dependency of Event_queue on Event_db_repository.
  The instantiation of Event_job_data was moved to class Event_worker_thread
  In place is a return of an object of Event_queue_element_for_exec is used
  later for instantiating Event_job_data.
  
  The `dropped` flag of Event_queue_element is passed over
  Event_queue_element_for_exec to the code in Event_worker_thread.
sql/event_queue.h:
  Removed dependency of Event_queue on Event_db_repository
  Removed dependency on Event_scheduler
sql/event_scheduler.cc:
  Added class Event_worker_thread, which is used during
  the execution of an event. It has a static init() method
  to get a pointer to Event_db_repository to be used for
  instantiation of Event_job_data object. This object it then
  executed.
sql/event_scheduler.h:
  Added class Event_worker_thread, which is used during
  the execution of an event.
sql/events.cc:
  Removed Events::open_event_table() because it was a product of
  a bad architecture.
sql/events.h:
  Removed friend definition, unneeded.
  
  Fixed Events::drop_event() to have the previous signature without
  bool only_from_disk
sql/sql_parse.cc:
  Fix call
2007-01-29 20:46:29 +03:00

149 lines
2.9 KiB
C++

#ifndef _EVENT_SCHEDULER_H_
#define _EVENT_SCHEDULER_H_
/* Copyright (C) 2004-2006 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
class Event_queue;
class Event_job_data;
class Event_db_repository;
class Events;
void
pre_init_event_thread(THD* thd);
bool
post_init_event_thread(THD* thd);
void
deinit_event_thread(THD *thd);
class Event_worker_thread
{
public:
static void
init(Events *events, Event_db_repository *db_repo)
{
db_repository= db_repo;
events_facade= events;
}
void
run(THD *thd, Event_queue_element_for_exec *event);
private:
void
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(){}
/* State changing methods follow */
bool
start();
bool
stop();
/*
Need to be public because has to be called from the function
passed to pthread_create.
*/
bool
run(THD *thd);
void
init_scheduler(Event_queue *queue);
void
deinit_scheduler();
void
init_mutexes();
void
deinit_mutexes();
/* Information retrieving methods follow */
bool
is_running();
void
dump_internal_status();
private:
uint
workers_count();
/* helper functions */
bool
execute_top(THD *thd, Event_queue_element_for_exec *event_name);
/* helper functions for working with mutexes & conditionals */
void
lock_data(const char *func, uint line);
void
unlock_data(const char *func, uint line);
void
cond_wait(THD *thd, struct timespec *abstime, const char* msg,
const char *func, uint line);
pthread_mutex_t LOCK_scheduler_state;
enum enum_state
{
UNINITIALIZED = 0,
INITIALIZED,
RUNNING,
STOPPING
};
/* This is the current status of the life-cycle of the scheduler. */
enum enum_state state;
THD *scheduler_thd;
pthread_cond_t COND_state;
Event_queue *queue;
uint mutex_last_locked_at_line;
uint mutex_last_unlocked_at_line;
const char* mutex_last_locked_in_func;
const char* mutex_last_unlocked_in_func;
bool mutex_scheduler_data_locked;
bool waiting_on_cond;
ulonglong started_events;
private:
/* Prevent use of these */
Event_scheduler(const Event_scheduler &);
void operator=(Event_scheduler &);
};
#endif /* _EVENT_SCHEDULER_H_ */