mariadb/sql/events.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

135 lines
2.8 KiB
C++

#ifndef _EVENT_H_
#define _EVENT_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 sp_name;
class Event_parse_data;
class Event_db_repository;
class Event_queue;
class Event_queue_element;
class Event_scheduler;
/* Return codes */
enum enum_events_error_code
{
OP_OK= 0,
OP_NOT_RUNNING,
OP_CANT_KILL,
OP_CANT_INIT,
OP_DISABLED_EVENT,
OP_LOAD_ERROR,
OP_ALREADY_EXISTS
};
int
sortcmp_lex_string(LEX_STRING s, LEX_STRING t, CHARSET_INFO *cs);
class Events
{
public:
/* The order should match the order in opt_typelib */
enum enum_opt_event_scheduler
{
EVENTS_OFF= 0,
EVENTS_ON= 1,
EVENTS_DISABLED= 4
};
static enum_opt_event_scheduler opt_event_scheduler;
static TYPELIB opt_typelib;
static TYPELIB var_typelib;
bool
init();
void
deinit();
void
init_mutexes();
void
destroy_mutexes();
bool
start_execution_of_events();
bool
stop_execution_of_events();
bool
is_execution_of_events_started();
static Events *
get_instance();
bool
create_event(THD *thd, Event_parse_data *parse_data, bool if_exists);
bool
update_event(THD *thd, Event_parse_data *parse_data, sp_name *rename_to);
bool
drop_event(THD *thd, LEX_STRING dbname, LEX_STRING name, bool if_exists);
void
drop_schema_events(THD *thd, char *db);
bool
show_create_event(THD *thd, LEX_STRING dbname, LEX_STRING name);
/* Needed for both SHOW CREATE EVENT and INFORMATION_SCHEMA */
static int
reconstruct_interval_expression(String *buf, interval_type interval,
longlong expression);
static int
fill_schema_events(THD *thd, TABLE_LIST *tables, COND * /* cond */);
void
dump_internal_status();
private:
bool
check_system_tables(THD *thd);
int
load_events_from_db(THD *thd);
/* Singleton DP is used */
Events();
~Events(){}
/* Singleton instance */
static Events singleton;
Event_queue *event_queue;
Event_scheduler *scheduler;
Event_db_repository *db_repository;
pthread_mutex_t LOCK_event_metadata;
bool check_system_tables_error;
/* Prevent use of these */
Events(const Events &);
void operator=(Events &);
};
#endif /* _EVENT_H_ */