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

1 files changed, 4 insertions, 0 deletions

diff --git a/mysql-test/t/events_scheduling.test b/mysql-test/t/events_scheduling.test
index e3b55685e65..ff9dfaad927 100644
--- a/mysql-test/t/events_scheduling.test
+++ b/mysql-test/t/events_scheduling.test
@@ -6,12 +6,16 @@ CREATE DATABASE IF NOT EXISTS events_test;
 USE events_test;
 
 SET GLOBAL event_scheduler=OFF;
+--echo Try agian to make sure it's allowed
+SET GLOBAL event_scheduler=OFF;
 SHOW VARIABLES LIKE 'event_scheduler';
 SET GLOBAL event_scheduler=1;
 SHOW VARIABLES LIKE 'event_scheduler';
 SET GLOBAL event_scheduler=0;
 SHOW VARIABLES LIKE 'event_scheduler';
 SET GLOBAL event_scheduler=ON;
+--echo Try again to make sure it's allowed
+SET GLOBAL event_scheduler=ON;
 SHOW VARIABLES LIKE 'event_scheduler';
 --error ER_WRONG_VALUE_FOR_VAR
 SET GLOBAL event_scheduler=DISABLED;