fix for bug #17619 Scheduler race conditions

- Scheduler is either initialized at server start or never.
  Starting & stopping is now suspending & resuming.
- The scheduler has clear OO interface
- Now all calls to the scheduler are synchronous
- GLOBAL event_scheduler uses thd::sys_var_tmp (see set_var.cc)
- External API is encapsulated into class Events
- Includes fixes for all comments of Kostja's review of 19.05.2005

Starting to merge into 5.1-release (5.1.10) and push


BitKeeper/etc/ignore:
  Added libmysqld/event_scheduler.cc to the ignore list
libmysqld/Makefile.am:
  executor -> scheduler
mysql-test/r/events.result:
  update result
mysql-test/r/events_bugs.result:
  update result
mysql-test/r/events_logs_tests.result:
  update result
mysql-test/r/events_microsec.result:
  update result
mysql-test/r/events_scheduling.result:
  update result
mysql-test/r/events_stress.result:
  update result
mysql-test/t/disabled.def:
  enable these tests
mysql-test/t/events.test:
  optimize the test a bit for speed, save some seconds runtime
  remove FULL from SHOW EVENTS
  mostly use I_S.EVENTS
mysql-test/t/events_bugs.test:
  Skip irrelevant for the current design tests - all events are loaded
  on server startup. Change in mysql.event will be visible on next server start.
  Don't use numeric error codes.
mysql-test/t/events_logs_tests.test:
  optimize the test a bit for speed
mysql-test/t/events_microsec.test:
   Skip irrelevant for the current design tests - all events are loaded
      on server startup. Change in mysql.event will be visible on next server start.
      Don't use numeric error codes.
mysql-test/t/events_scheduling.test:
  broader test
mysql-test/t/events_stress.test:
  Rework the test to the new architecture of suspending/resuming.
  Use less events, no need for thousands, hundreds is still ok.
sql/Makefile.am:
  executor -> scheduler
sql/cmakelists.txt:
  executor -> scheduler
sql/event.cc:
  - remove todo comments
  - remove unneded evex_queue abstraction functions
  - move events_init() and events_shutdown() from event_executor.cc to here
  - export db_create_event
  - remove evex_load_and_compile_event, part of class Event_scheduler
  - integrate the public interface found in event.h and used by sql_parse.cc
    to use the new class Event_scheduler.
sql/event.h:
  - add COND_finished so if one thread kills a running event it waits on this
  - export callback event_timed_definer_equal, event_timed_identifier_equal(),
    event_timed_name_equal and event_timed_db_equal()
    to be used by Event_scheduler::drop_matching_events()
  - cleanup event.h
  - encapsulated all external interface into class Events
sql/event_executor.cc:
  make it empty, will delete after that
sql/event_priv.h:
  - more things in the private header
  - remove event queue abstraction functions. tightly bind to QUEUE
  - export privately db_drop_event, db_find_event, db_create_event()
  - made change_security_context() and restore_security_context() free functions
sql/event_timed.cc:
  - fix calculation of time when ENDS is set (STARTS is always set)
  - during Event_timed::compile() set the right Security_ctx. Prevents a crash
        during Event_scheduler::load_events_from_db()
  - add Event_timed::kill_thread()
  - implement event_timed_*_equal()
  - made change_security_context() and restore_security_context() free functions.
  - Comments cleanups
sql/lex.h:
  new word scheduler for SHOW SCHEDULER STATUS (available only debug builds)
sql/log.cc:
  move these from event_scheduler.cc
sql/mysql_priv.h:
  refactor kill_one_thread
  export sql_print_message_func and sql_print_message_handlers
sql/mysqld.cc:
  In close_connections, called by kill_server() skip the main scheduler
  thread and use events_shutdown() for shutting down the scheduler, in the same
  manner it's done for RPL.
  Add a new value to --event-scheduler :
  0 <- No scheduler available
  1 <- Start with scheduler enabled
  2 <- Start with scheduler suspended
sql/repl_failsafe.cc:
  refactor thd::system_thread to be an enum
sql/set_var.cc:
  move sys_var_event_executor::update() to set_var.cc
  executor -> scheduler
  use thd::sys_var_tmp
sql/set_var.h:
  executor -> scheduler
sql/share/errmsg.txt:
  3 new error messages
sql/sql_class.cc:
  refactor thd::system_thread to be an enum . more type-safety
sql/sql_class.h:
  refactor thd::system_thread to be an enum . more type-safety
sql/sql_db.cc:
  get the error from evex_drop_schema_events
sql/sql_error.h:
  export warning_level_names
sql/sql_lex.h:
  new command SHOW SCHEDULER STATUS, available only in debug build and
  for debug purposes.
sql/sql_parse.cc:
  refactor kill_one_thread() -> does the *dirty* work, and sql_kill
  just the reporting.
  add handler for SQLCOM_SHOW_SCHEDULER_STATUS
sql/sql_show.cc:
  fix verbosity handling (this will be obsoleted anyway by the fix for 17394).
sql/sql_yacc.yy:
  remove FULL from SHOW EVENTS
  add SHOW SCHEDULER STATUS in debug builds
sql/table.cc:
  Fix valgrind warning.

1 files changed, 25 insertions, 27 deletions

diff --git a/mysql-test/r/events.result b/mysql-test/r/events.result
index 01d206be7cb..d02a2af3c9f 100644
--- a/mysql-test/r/events.result
+++ b/mysql-test/r/events.result
@@ -17,13 +17,13 @@ db_x
 SHOW TABLES FROM db_x;
 Tables_in_db_x
 x_table
-SET GLOBAL event_scheduler=0;
+SET GLOBAL event_scheduler=2;
 DROP EVENT e_x1;
 DROP EVENT e_x2;
 DROP DATABASE db_x;
 DROP USER pauline@localhost;
 USE events_test;
-SET GLOBAL event_scheduler=0;
+SET GLOBAL event_scheduler=2;
 drop event if exists event1;
 Warnings:
 Note	1305	Event event1 does not exist
@@ -100,7 +100,7 @@ a
 800219
 drop event non_qualif_ev;
 drop table non_qualif;
-set global event_scheduler = 0;
+set global event_scheduler = 2;
 create table t_event3 (a int, b float);
 drop event if exists event3;
 Warnings:
@@ -324,18 +324,18 @@ events_test	one_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
 events_test	three_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
 events_test	two_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
 "This should show us only 3 events:";
-SHOW FULL EVENTS;
+SHOW EVENTS;
 Db	Name	Definer	Type	Execute at	Interval value	Interval field	Starts	Ends	Status
 events_test	one_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
 events_test	three_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
 events_test	two_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
 "This should show us only 2 events:";
-SHOW FULL EVENTS LIKE 't%event';
+SHOW EVENTS LIKE 't%event';
 Db	Name	Definer	Type	Execute at	Interval value	Interval field	Starts	Ends	Status
 events_test	three_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
 events_test	two_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
 "This should show us no events:";
-SHOW FULL EVENTS FROM test LIKE '%';
+SHOW EVENTS FROM test LIKE '%';
 Db	Name	Definer	Type	Execute at	Interval value	Interval field	Starts	Ends	Status
 DROP DATABASE events_test2;
 "should see 1 event:";
@@ -343,11 +343,8 @@ SHOW EVENTS;
 Db	Name	Definer	Type	Execute at	Interval value	Interval field	Starts	Ends	Status
 events_test	one_event	root@localhost	RECURRING	NULL	10	SECOND	#	#	ENABLED
 "we should see 4 events now:";
-SHOW FULL EVENTS;
+SHOW EVENTS;
 Db	Name	Definer	Type	Execute at	Interval value	Interval field	Starts	Ends	Status
-events_test	one_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
-events_test	three_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
-events_test	two_event	ev_test@localhost	RECURRING	NULL	20	SECOND	#	#	ENABLED
 events_test	one_event	root@localhost	RECURRING	NULL	10	SECOND	#	#	ENABLED
 SELECT EVENT_CATALOG, EVENT_SCHEMA, EVENT_NAME, DEFINER, EVENT_BODY, EVENT_TYPE, EXECUTE_AT, INTERVAL_VALUE, INTERVAL_FIELD, STATUS,ON_COMPLETION, EVENT_COMMENT from information_schema.events;
 EVENT_CATALOG	EVENT_SCHEMA	EVENT_NAME	DEFINER	EVENT_BODY	EVENT_TYPE	EXECUTE_AT	INTERVAL_VALUE	INTERVAL_FIELD	STATUS	ON_COMPLETION	EVENT_COMMENT
@@ -373,12 +370,12 @@ ERROR HY000: Incorrect AT value: 'definitely not a datetime'
 set names utf8;
 create event задачка on schedule every 123 minute starts now() ends now() + interval 1 month do select 1;
 drop event задачка;
-set event_scheduler=0;
+set event_scheduler=2;
 ERROR HY000: Variable 'event_scheduler' is a GLOBAL variable and should be set with SET GLOBAL
-set global event_scheduler=2;
-ERROR 42000: Variable 'event_scheduler' can't be set to the value of '2'
+set global event_scheduler=3;
+ERROR 42000: Variable 'event_scheduler' can't be set to the value of '3'
 "DISABLE the scheduler. Testing that it does not work when the variable is 0"
-set global event_scheduler=0;
+set global event_scheduler=2;
 select definer, name, db from mysql.event;
 definer	name	db
 select get_lock("test_lock1", 20);
@@ -389,9 +386,10 @@ create event закачка on schedule every 10 hour do select get_lock("test_l
 select definer, name, db from mysql.event;
 definer	name	db
 root@localhost	закачка	events_test
-"Should be 0 processes"
+"Should be only 1 process"
 select /*1*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 user	host	db	command	state	info
+event_scheduler	localhost	NULL	Connect	Suspended	NULL
 select release_lock("test_lock1");
 release_lock("test_lock1")
 1
@@ -409,11 +407,12 @@ get_lock("test_lock2", 20)
 create event закачка on schedule every 10 hour do select get_lock("test_lock2", 20);
 "Let some time pass to the event starts"
 "Should have only 2 processes: the scheduler and the locked event"
-select /*1*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
+select /*2*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 user	host	db	command	state	info
 event_scheduler	localhost	NULL	Connect	Sleeping	NULL
 root	localhost	events_test	Connect	User lock	select get_lock("test_lock2", 20)
 "Release the mutex, the event worker should finish."
+"Release the mutex, the event worker should finish."
 select release_lock("test_lock2");
 release_lock("test_lock2")
 1
@@ -423,21 +422,17 @@ select get_lock("test_lock2_1", 20);
 get_lock("test_lock2_1", 20)
 1
 create event закачка21 on schedule every 10 hour do select get_lock("test_lock2_1", 20);
-"Should see 1 process, locked on get_lock("
-"Shutting down the scheduler, it should wait for the running event"
-set global event_scheduler=0;
-"Should have only 2 processes: the scheduler and the locked event"
-select /*4*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
+"Should have only 3 processes: the scheduler, our conn and the locked event"
+select /*3*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 user	host	db	command	state	info
 event_scheduler	localhost	NULL	Connect	Sleeping	NULL
 root	localhost	events_test	Connect	User lock	select get_lock("test_lock2_1", 20)
-"Release the lock so the child process should finish. Hence the scheduler also"
-select release_lock("test_lock2_1");
-release_lock("test_lock2_1")
-1
-"Should see 0 processes now:"
-select /*5*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
+set global event_scheduler=2;
+"Should have only our process now:"
+select /*4*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 user	host	db	command	state	info
+event_scheduler	localhost	NULL	Connect	Suspended	NULL
+root	localhost	events_test	Connect	User lock	select get_lock("test_lock2_1", 20)
 drop event закачка21;
 create table t_16 (s1 int);
 create trigger t_16_bi before insert on t_16 for each row create event  e_16 on schedule every 1 second do set @a=5;
@@ -457,6 +452,9 @@ select 2;
 select event_schema, event_name, definer, event_body from information_schema.events where event_name='white_space';
 event_schema	event_name	definer	event_body
 events_test	white_space	root@localhost	select 2
+select event_schema, event_name, definer, event_body from information_schema.events where event_name='white_space';
+event_schema	event_name	definer	event_body
+events_test	white_space	root@localhost	select 2
 drop event white_space;
 create event white_space on schedule every 10 hour disable do	select 3;
 select event_schema, event_name, definer, event_body from information_schema.events where event_name='white_space';