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


mysql-test/r/events.result:
  Update results.
mysql-test/r/events_bugs.result:
  Update results.
mysql-test/r/events_restart_phase1.result:
  Update results.
mysql-test/r/events_restart_phase2.result:
  Update results.
mysql-test/r/events_restart_phase3.result:
  Update results.
mysql-test/r/events_scheduling.result:
  Update results.
mysql-test/r/events_time_zone.result:
  Update results.
mysql-test/t/events.test:
  Add new tests for tampering with mysql.event and some more
  tests for sub-statements, LOCK TABLES mode and pre-locking.
mysql-test/t/events_bugs.test:
  Move the non-concurrent part of test for Bug 16420 to this file.
mysql-test/t/events_restart_phase1.test:
  Rewrite events_restart_* tests to take into account that now
  we check mysql.event table only once, at server startup.
mysql-test/t/events_restart_phase2.test:
  Rewrite events_restart_* tests to take into account that now
  we check mysql.event table only once, at server startup.
mysql-test/t/events_restart_phase3.test:
  Rewrite events_restart_* tests to take into account that now
  we check mysql.event table only once, at server startup.
mysql-test/t/events_scheduling.test:
  Add more coverage for event_scheduler global variable.
mysql-test/t/events_time_zone.test:
  Move the non-concurrent part of the tests for Bug 16420 to 
  events_bugs.test
sql/event_data_objects.cc:
  Move update_timing_fields functionality to Event_db_repository.
  Make loading of events from a table record more robust to tampering
  with the table - now we do not check mysql.event on every table open.
sql/event_data_objects.h:
  Cleanup.
sql/event_db_repository.cc:
  Now Event_db_repository is responsible for table I/O only.
  All the logic of events DDL is handled outside, in Events class please
  refer to the added test coverage to see how this change affected
  the behavior of Event Scheduler.
  Dependency on sp_head.h and sp.h removed.
  Make this module robust to tweaks with mysql.event table.
  Move check_system_tables from events.cc to this file
sql/event_db_repository.h:
  Cleanup declarations (remove unused ones, change return type to bool
  from int).
sql/event_queue.cc:
  Update to adapt to the new start up scheme of the Event Scheduler.
sql/event_queue.h:
  Cleanup declarations.
sql/event_scheduler.cc:
  Make all the error messages uniform:
  [SEVERITY] Event Scheduler: [user][schema.event] message
  Using append_identifier for error logging was an overkill - we may 
  need it only if the system character set may have NUL (null character)
  as part of a valid identifier, this is currently never the case, 
  whereas additional quoting did not look nice in the log.
sql/event_scheduler.h:
  Cleanup the headers.
sql/events.cc:
  Use a different start up procedure of Event Scheduler:
  - at start up, try to check the system tables first.
  If they are not up-to-date, disable the scheduler.
  - try to load all the active events. In case of a load error, abort
  start up.
  - do not parse an event on start up. Parsing only gives some information
  about event validity, but far not all.
  Consolidate the business logic of Events DDL in this module.
  Now opt_event_scheduler may change after start up and thus is protected
  by LOCK_event_metadata mutex.
sql/events.h:
  Use all-static-data-members approach to implement Singleton pattern.
sql/mysqld.cc:
  New invocation scheme of Events. Move some logic to events.cc.
  Initialize the scheduler before reporting "Ready for connections".
sql/set_var.cc:
  Clean up sys_var_thd_sql_mode::symbolic_mode_representation
  to work with a LEX_STRING.
  Move more logic related to @@events_scheduler global variable to Events
  module.
sql/set_var.h:
  Update declarations.
sql/share/errmsg.txt:
  If someone tampered with mysql.event table after the server has
  started we no longer give him/her a complete report what was actually 
  broken. Do not send the user to look at the error log in such case,
  as there is nothing there (check_table_intact is not executed).
sql/sp_head.cc:
  Update to a new declaration of 
  sys_var_thd_sql_mode::symbolic_mode_representation
sql/sql_db.cc:
  New invocation scheme of Events module.
sql/sql_parse.cc:
  Move more logic to Events module. Make sure that we are consistent
  in the way access rights are checked for Events DDL: always
  after committing the current transaction and checking the system tables.
sql/sql_show.cc:
  Update to the new declarations of 
  sys_var_thd_sql_mode::symbolic_mode_representation
sql/sql_test.cc:
  New invocation scheme of events.
sql/table.cc:
  mysql.event is a system table.
  Update check_table_intact to be concurrent, more verbose, and less smart.
sql/table.h:
  Add a helper method.
mysql-test/r/events_trans.result:
  New BitKeeper file ``mysql-test/r/events_trans.result''
mysql-test/t/events_trans.test:
  New BitKeeper file ``mysql-test/t/events_trans.test'':
  test cases for Event Scheduler that require a transactional
  storage engine.

1 files changed, 337 insertions, 37 deletions

diff --git a/mysql-test/t/events.test b/mysql-test/t/events.test
index 39bc1063ace..c8054e49da4 100644
--- a/mysql-test/t/events.test
+++ b/mysql-test/t/events.test
@@ -1,7 +1,13 @@
 # Can't test with embedded server that doesn't support grants
 -- source include/not_embedded.inc
 
-create database if not exists events_test;
+--disable_warnings
+drop database if exists events_test;
+drop database if exists db_x;
+drop database if exists mysqltest_db2;
+drop database if exists mysqltest_no_such_database;
+--enable_warnings
+create database events_test;
 use events_test;
 
 #
@@ -215,62 +221,161 @@ set names latin1;
 #
 
 #
-# mysql.event intact checking start
+# mysql.event intact checking
+# Check that the server does not crash if
+# one has destroyed or tampered with the event table. 
+# Please see see for events_restart_phase* tests to 
+# see the server behavior at start up with bad mysql.event
+# table.
 #
-# There should be at least 1 second between the ALTERs or we can't catch the change of create_time!!
+#
+--echo Create a test event. Only event metadata is relevant, 
+--echo the actual schedule and body are not.
 #
 CREATE EVENT intact_check ON SCHEDULE EVERY 10 HOUR DO SELECT "nothing";
 --replace_column 8 # 9 #
 SHOW EVENTS;
-ALTER TABLE mysql.event ADD dummy INT FIRST;
---error ER_COL_COUNT_DOESNT_MATCH_CORRUPTED
-SHOW EVENTS;
-ALTER TABLE mysql.event DROP dummy, ADD dummy2 VARCHAR(64) FIRST;
---error ER_COL_COUNT_DOESNT_MATCH_CORRUPTED
-SHOW EVENTS;
-ALTER TABLE mysql.event DROP dummy2;
+#
+--echo Try to alter mysql.event: the server should fail to load
+--echo event information after mysql.event was tampered with.
+--echo 
+--echo First, let's add a column to the end and make sure everything
+--echo works as before
+--echo 
+ALTER TABLE mysql.event ADD dummy INT;
 --replace_column 8 # 9 #
 SHOW EVENTS;
+SELECT event_name FROM INFORMATION_SCHEMA.events;
+--replace_regex /STARTS '[^']+'/STARTS '#'/
+SHOW CREATE EVENT intact_check;
+--error ER_EVENT_DOES_NOT_EXIST
+DROP EVENT no_such_event;
+CREATE EVENT intact_check_1 ON SCHEDULE EVERY 5 HOUR DO SELECT 5;
+ALTER EVENT intact_check_1 ON SCHEDULE EVERY 8 HOUR DO SELECT 8;
+ALTER EVENT intact_check_1 RENAME TO intact_check_2;
+--error ER_EVENT_DOES_NOT_EXIST
+DROP EVENT intact_check_1;
+DROP EVENT intact_check_2;
+DROP EVENT intact_check;
+DROP DATABASE IF EXISTS mysqltest_no_such_database;
+CREATE DATABASE mysqltest_db2;
+DROP DATABASE mysqltest_db2;
+SELECT @@event_scheduler;
+SHOW VARIABLES LIKE 'event_scheduler';
+SET GLOBAL event_scheduler=OFF;
+# Clean up
+ALTER TABLE mysql.event DROP dummy;
+CREATE EVENT intact_check ON SCHEDULE EVERY 10 HOUR DO SELECT "nothing";
+--echo 
+--echo Now let's add a column to the first position: the server
+--echo expects to see event schema name there
+--echo 
+ALTER TABLE mysql.event ADD dummy INT FIRST;
+--error ER_CANNOT_LOAD_FROM_TABLE
+SHOW EVENTS;
+--error ER_CANNOT_LOAD_FROM_TABLE
+SELECT event_name FROM INFORMATION_SCHEMA.events;
+--error ER_EVENT_DOES_NOT_EXIST
+SHOW CREATE EVENT intact_check;
+--error ER_EVENT_DOES_NOT_EXIST
+DROP EVENT no_such_event;
+--error ER_CANNOT_LOAD_FROM_TABLE
+CREATE EVENT intact_check_1 ON SCHEDULE EVERY 5 HOUR DO SELECT 5;
+--error ER_EVENT_DOES_NOT_EXIST
+ALTER EVENT intact_check_1 ON SCHEDULE EVERY 8 HOUR DO SELECT 8;
+--error ER_EVENT_DOES_NOT_EXIST
+ALTER EVENT intact_check_1 RENAME TO intact_check_2;
+--error ER_EVENT_DOES_NOT_EXIST
+DROP EVENT intact_check_1;
+--error ER_EVENT_DOES_NOT_EXIST
+DROP EVENT intact_check_2;
+--error ER_EVENT_DOES_NOT_EXIST
+DROP EVENT intact_check;
+# Should work OK
+DROP DATABASE IF EXISTS mysqltest_no_such_database;
+CREATE DATABASE mysqltest_db2;
+DROP DATABASE mysqltest_db2;
+SELECT @@event_scheduler;
+SHOW VARIABLES LIKE 'event_scheduler';
+SET GLOBAL event_scheduler=OFF;
+--echo Clean up
+ALTER TABLE mysql.event DROP dummy;
+DELETE FROM mysql.event;
+CREATE EVENT intact_check ON SCHEDULE EVERY 10 HOUR DO SELECT "nothing";
+--echo Back up the table, further changes are not reversible
 CREATE TABLE event_like LIKE mysql.event;
 INSERT INTO event_like SELECT * FROM mysql.event;
-#sleep a bit or we won't catch the change of time
---sleep 1.1
-ALTER TABLE mysql.event MODIFY db char(64) character set cp1251 default '';
---error ER_CANNOT_LOAD_FROM_TABLE
-SELECT event_name FROM INFORMATION_SCHEMA.EVENTS;
-ALTER TABLE mysql.event MODIFY db char(20) character set utf8 collate utf8_bin default '';
-#wait a bit or we won't see the difference because of seconds resolution
---sleep 1.1
-SHOW CREATE TABLE mysql.event;
+--echo 
+--echo Drop some columns and try more checks. 
+--echo
+--echo 
+ALTER TABLE mysql.event DROP comment, DROP starts;
 --error ER_CANNOT_LOAD_FROM_TABLE
-SELECT event_name FROM INFORMATION_SCHEMA.EVENTS;
---sleep 1.1
-ALTER TABLE mysql.event MODIFY db char(64) character set utf8 collate utf8_bin default '';
---sleep 1.1
---echo "This should work"
---replace_column 8 # 9 #
 SHOW EVENTS;
---sleep 1.1
-ALTER TABLE mysql.event MODIFY db char(64) character set cp1251 default '';
 --error ER_CANNOT_LOAD_FROM_TABLE
 SELECT event_name FROM INFORMATION_SCHEMA.EVENTS;
---sleep 1.1
-ALTER TABLE mysql.event MODIFY db varchar(64) character set utf8 collate utf8_bin default '';
---sleep 1.1
 --error ER_CANNOT_LOAD_FROM_TABLE
-SELECT event_name FROM INFORMATION_SCHEMA.EVENTS;
---sleep 1.1
-ALTER TABLE mysql.event DROP comment, DROP starts;
---sleep 1.1
+SHOW CREATE EVENT intact_check;
+--error ER_EVENT_DOES_NOT_EXIST
+DROP EVENT no_such_event;
 --error ER_COL_COUNT_DOESNT_MATCH_CORRUPTED
-SELECT event_name FROM INFORMATION_SCHEMA.EVENTS;
+CREATE EVENT intact_check_1 ON SCHEDULE EVERY 5 HOUR DO SELECT 5;
+--error ER_EVENT_DOES_NOT_EXIST
+ALTER EVENT intact_check_1 ON SCHEDULE EVERY 8 HOUR DO SELECT 8;
+--error ER_EVENT_DOES_NOT_EXIST
+ALTER EVENT intact_check_1 RENAME TO intact_check_2;
+--error ER_EVENT_DOES_NOT_EXIST
+DROP EVENT intact_check_1;
+--error ER_EVENT_DOES_NOT_EXIST
+DROP EVENT intact_check_2;
+# Should succeed
+DROP EVENT intact_check;
+DROP DATABASE IF EXISTS mysqltest_no_such_database;
+CREATE DATABASE mysqltest_db2;
+DROP DATABASE mysqltest_db2;
+SELECT @@event_scheduler;
+SHOW VARIABLES LIKE 'event_scheduler';
+SET GLOBAL event_scheduler=OFF;
+--echo 
+--echo Now drop the table, and test again
+--echo
+--echo 
 DROP TABLE mysql.event;
+--error ER_NO_SUCH_TABLE
+SHOW EVENTS;
+--error ER_NO_SUCH_TABLE
+SELECT event_name FROM INFORMATION_SCHEMA.events;
+--error ER_NO_SUCH_TABLE
+SHOW CREATE EVENT intact_check;
+--error ER_NO_SUCH_TABLE
+DROP EVENT no_such_event;
+--error ER_NO_SUCH_TABLE
+CREATE EVENT intact_check_1 ON SCHEDULE EVERY 5 HOUR DO SELECT 5;
+--error ER_NO_SUCH_TABLE
+ALTER EVENT intact_check_1 ON SCHEDULE EVERY 8 HOUR DO SELECT 8;
+--error ER_NO_SUCH_TABLE
+ALTER EVENT intact_check_1 RENAME  TO intact_check_2;
+--error ER_NO_SUCH_TABLE
+DROP EVENT intact_check_1;
+--error ER_NO_SUCH_TABLE
+DROP EVENT intact_check_2;
+--error ER_NO_SUCH_TABLE
+DROP EVENT intact_check;
+DROP DATABASE IF EXISTS mysqltest_no_such_database;
+CREATE DATABASE mysqltest_db2;
+DROP DATABASE mysqltest_db2;
+--echo OK, there is an unnecessary warning about the non-existent table 
+--echo but it's not easy to fix and no one complained about it.
+--echo A similar warning is printed if mysql.proc is missing.
+SHOW WARNINGS;
+SELECT @@event_scheduler;
+SHOW VARIABLES LIKE 'event_scheduler';
+SET GLOBAL event_scheduler=OFF;
+--echo Restore the original table.
 CREATE TABLE mysql.event like event_like;
-INSERT INTO  mysql.event SELECT * FROM event_like;
 DROP TABLE event_like;
 --replace_column 8 # 9 #
 SHOW EVENTS;
-DROP EVENT intact_check;
 #
 # mysql.event intact checking end
 #
@@ -424,5 +529,200 @@ SHOW EVENTS FROM aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
 SHOW EVENTS FROM ``;
 
 SHOW EVENTS FROM `events\\test`;
+#
+# A check for events SQL under LOCK TABLES and in pre-locked mode.
+#
+--echo
+--echo LOCK TABLES mode.
+--echo 
+#
+# SHOW CREATE EVENT and INFORMATION_SCHEMA.events are available and 
+# cause an implicit lock/unlock of mysql.event table, regardless of the
+# currently locked tables.
+#
+create table t1 (a int);
+create event e1 on schedule every 10 hour do select 1;
+#
+lock table t1 read;
+#
+--replace_regex /STARTS '[^']+'/STARTS '#'/
+show create event e1;
+select event_name from information_schema.events;
+--error ER_TABLE_NOT_LOCKED
+create event e2 on schedule every 10 hour do select 1;
+--error ER_TABLE_NOT_LOCKED
+alter event e2 disable;
+--error ER_TABLE_NOT_LOCKED
+alter event e2 rename to e3;
+--error ER_TABLE_NOT_LOCKED
+drop event e2;
+--error ER_TABLE_NOT_LOCKED
+drop event e1;
+unlock tables;
+#
+lock table t1 write;
+#
+--replace_regex /STARTS '[^']+'/STARTS '#'/
+show create event e1;
+select event_name from information_schema.events;
+--error ER_TABLE_NOT_LOCKED
+create event e2 on schedule every 10 hour do select 1;
+--error ER_TABLE_NOT_LOCKED
+alter event e2 disable;
+--error ER_TABLE_NOT_LOCKED
+alter event e2 rename to e3;
+--error ER_TABLE_NOT_LOCKED
+drop event e2;
+--error ER_TABLE_NOT_LOCKED
+drop event e1;
+unlock tables;
+#
+lock table t1 read, mysql.event read;
+#
+--replace_regex /STARTS '[^']+'/STARTS '#'/
+show create event e1;
+select event_name from information_schema.events;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+create event e2 on schedule every 10 hour do select 1;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+alter event e2 disable;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+alter event e2 rename to e3;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+drop event e2;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+drop event e1;
+unlock tables;
+#
+lock table t1 write, mysql.event read;
+#
+--replace_regex /STARTS '[^']+'/STARTS '#'/
+show create event e1;
+select event_name from information_schema.events;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+create event e2 on schedule every 10 hour do select 1;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+alter event e2 disable;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+alter event e2 rename to e3;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+drop event e2;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+drop event e1;
+unlock tables;
+#
+--error ER_WRONG_LOCK_OF_SYSTEM_TABLE
+lock table t1 read, mysql.event write;
+#
+--error ER_WRONG_LOCK_OF_SYSTEM_TABLE
+lock table t1 write, mysql.event write;
+#
+lock table mysql.event write;
+--replace_regex /STARTS '[^']+'/STARTS '#'/
+show create event e1;
+select event_name from information_schema.events;
+create event e2 on schedule every 10 hour do select 1;
+alter event e2 disable;
+alter event e2 rename to e3;
+drop event e3;
+drop event e1;
+unlock tables;
+--echo Make sure we have left no events 
+select event_name from information_schema.events;
+--echo
+--echo Events in sub-statements, events and prelocking
+--echo 
+--echo 
+create event e1 on schedule every 10 hour do select 1;
+delimiter |;
+--error ER_SP_NO_RETSET
+create function f1() returns int
+begin
+  show create event e1;
+  return 1;
+end|
+--error ER_SP_NO_RETSET
+create trigger trg before insert on t1 for each row
+begin
+  show create event e1;
+end|
+--error ER_SP_NO_RETSET
+create function f1() returns int
+begin
+  select event_name from information_schema.events;
+  return 1;
+end|
+--error ER_SP_NO_RETSET
+create trigger trg before insert on t1 for each row
+begin
+  select event_name from information_schema.events;
+end|
+--error ER_EVENT_RECURSION_FORBIDDEN
+create function f1() returns int
+begin
+  create event e2 on schedule every 10 hour do select 1;
+  return 1;
+end|
+--error ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG
+create function f1() returns int
+begin
+  alter event e1 rename to e2;
+  return 1;
+end|
+--error ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG
+create function f1() returns int
+begin
+  drop event e2;
+  return 1;
+end|
+--echo ----------------------------------------------------------------------
+create trigger trg before insert on t1 for each row
+begin
+  set new.a= f1();
+end|
+create function f1() returns int
+begin
+  call p1();
+  return 0;
+end|
+create procedure p1()
+begin
+  select event_name from information_schema.events;
+end|
+--error ER_SP_NO_RETSET
+insert into t1 (a) values (1)|
+drop procedure p1|
+create procedure p1()
+begin
+  show create event e1; 
+end|
+--error ER_SP_NO_RETSET
+insert into t1 (a) values (1)|
+drop procedure p1|
+create procedure p1()
+begin
+  create temporary table tmp select event_name from information_schema.events;
+end|
+--echo expected to work, since we redirect the output into a tmp table
+insert into t1 (a) values (1)|
+select * from tmp|
+drop temporary table tmp|
+drop procedure p1|
+create procedure p1()
+begin
+  alter event e1 rename to e2;
+end|
+--error ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG
+insert into t1 (a) values (1)|
+drop procedure p1|
+create procedure p1()
+begin
+  drop event e1;
+end|
+--error ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG
+insert into t1 (a) values (1)|
+drop table t1|
+drop event e1|
+delimiter ;|
 
 drop database events_test;