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, 17 insertions, 6 deletions

diff --git a/sql/sql_class.h b/sql/sql_class.h
index 04095ff9acd..a0971b22d3d 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -629,6 +629,8 @@ public:
   {
     return (*priv_host ? priv_host : (char *)"%");
   }
+  
+  bool set_user(char *user_arg);
 };
 
 
@@ -770,6 +772,19 @@ public:
 };
 
 
+/* Flags for the THD::system_thread variable */
+enum enum_thread_type
+{
+  NON_SYSTEM_THREAD= 0,
+  SYSTEM_THREAD_DELAYED_INSERT= 1,
+  SYSTEM_THREAD_SLAVE_IO= 2,
+  SYSTEM_THREAD_SLAVE_SQL= 4,
+  SYSTEM_THREAD_NDBCLUSTER_BINLOG= 8,
+  SYSTEM_THREAD_EVENT_SCHEDULER= 16,
+  SYSTEM_THREAD_EVENT_WORKER= 32
+};
+
+
 /*
   For each client connection we create a separate thread with THD serving as
   a thread/connection descriptor
@@ -1103,7 +1118,8 @@ public:
   long	     dbug_thread_id;
   pthread_t  real_id;
   uint	     tmp_table, global_read_lock;
-  uint	     server_status,open_options,system_thread;
+  uint	     server_status,open_options;
+  enum enum_thread_type system_thread;
   uint32     db_length;
   uint       select_number;             //number of select (used for EXPLAIN)
   /* variables.transaction_isolation is reset to this after each commit */
@@ -1404,11 +1420,6 @@ public:
 
 #define reenable_binlog(A)   (A)->options= tmp_disable_binlog__save_options;}
 
-/* Flags for the THD::system_thread (bitmap) variable */
-#define SYSTEM_THREAD_DELAYED_INSERT 1
-#define SYSTEM_THREAD_SLAVE_IO 2
-#define SYSTEM_THREAD_SLAVE_SQL 4
-#define SYSTEM_THREAD_NDBCLUSTER_BINLOG 8
 
 /*
   Used to hold information about file and file structure in exchainge