WL#3337 (Event scheduler new architecture)

Post-review fixes. Mostly whitespace, int-to-bool return value, fixed comments sql/Makefile.am: compile all submodules of Events before compiling the facade sql/event_data_objects.cc: - Use initialization list - Clean whitespaces - Shorten comments - Fix comments sql/event_data_objects.h: - Fix whitespace sql/event_db_repository.cc: - Change return type from int to bool where only one error code is returned. - Don't use macros but get the maximal number of characters in a column from the column - Fix comments - Make functions which has return value but it's not used - void. sql/event_db_repository.h: - Methods with only one error code int -> bool return value - Remove declaration of fill_schema_events, a function that does not exist sql/event_queue.cc: - Use initialization lists - Let find_n_remove_event delete the object thus making the code more robust. The caller could forget to destruct the object. In addition, find_n_remove_element() does not return a value. - Move check_system_tables() to class Events - Fix comments sql/event_queue.h: - Whitespace changes - init_queue() should allow passing of THD - check_system_tables moved to class Events - find_n_remove_event() is now void sql/event_scheduler.cc: - Initialize res before use - Remove end stop from message sql/event_scheduler.h: Add uninitialized state. The scheduler is in it before init_scheduler() is called. The rationale is that otherwise state has no value before the call. If the system tables were damaged the scheduler won't be initialized but in Events::deinit() Event_scheduler::stop() will be called and this will touch state, generating valgrind warning at minimum. sql/events.cc: - Whitespace changes - Fix comments - Make methods which have only one error code be bool instead of int - Create temporarily a THD to be used for the initialization of Event_queue - Event_queue::check_system_tables() moved to Events::check_system_tables - is_started() is renamed to is_execution_of_events_started() sql/events.h: - Whitespace changes - When a method returns only one error code it should be bool, not int - is_started() renamed to is_execution_of_events_started() sql/set_var.cc: is_started() is renamed to is_execution_of_events_started() sql/sql_db.cc: The return code is not used, thus don't return anything and drop_schema_events() is now void. sql/sql_yacc.yy: - Fix comments - Remove unneeded initialization which is performed in lex_init() sql/share/errmsg.txt: New error message sql/table.cc: - Fix comments - make table_check_intact() accespt const *table_def sql/table.h: Make table_check_intact() accespt const *table_def

WL#3337 (Event scheduler new architecture)
Post-review fixes. Mostly whitespace, int-to-bool return value, fixed comments sql/Makefile.am: compile all submodules of Events before compiling the facade sql/event_data_objects.cc: - Use initialization list - Clean whitespaces - Shorten comments - Fix comments sql/event_data_objects.h: - Fix whitespace sql/event_db_repository.cc: - Change return type from int to bool where only one error code is returned. - Don't use macros but get the maximal number of characters in a column from the column - Fix comments - Make functions which has return value but it's not used - void. sql/event_db_repository.h: - Methods with only one error code int -> bool return value - Remove declaration of fill_schema_events, a function that does not exist sql/event_queue.cc: - Use initialization lists - Let find_n_remove_event delete the object thus making the code more robust. The caller could forget to destruct the object. In addition, find_n_remove_element() does not return a value. - Move check_system_tables() to class Events - Fix comments sql/event_queue.h: - Whitespace changes - init_queue() should allow passing of THD - check_system_tables moved to class Events - find_n_remove_event() is now void sql/event_scheduler.cc: - Initialize res before use - Remove end stop from message sql/event_scheduler.h: Add uninitialized state. The scheduler is in it before init_scheduler() is called. The rationale is that otherwise state has no value before the call. If the system tables were damaged the scheduler won't be initialized but in Events::deinit() Event_scheduler::stop() will be called and this will touch state, generating valgrind warning at minimum. sql/events.cc: - Whitespace changes - Fix comments - Make methods which have only one error code be bool instead of int - Create temporarily a THD to be used for the initialization of Event_queue - Event_queue::check_system_tables() moved to Events::check_system_tables - is_started() is renamed to is_execution_of_events_started() sql/events.h: - Whitespace changes - When a method returns only one error code it should be bool, not int - is_started() renamed to is_execution_of_events_started() sql/set_var.cc: is_started() is renamed to is_execution_of_events_started() sql/sql_db.cc: The return code is not used, thus don't return anything and drop_schema_events() is now void. sql/sql_yacc.yy: - Fix comments - Remove unneeded initialization which is performed in lex_init() sql/share/errmsg.txt: New error message sql/table.cc: - Fix comments - make table_check_intact() accespt const *table_def sql/table.h: Make table_check_intact() accespt const *table_def
2ee9a827 · unknown · 09e7ac2d · 2ee9a827 · 2ee9a827 · 2ee9a827
Commit 2ee9a827 authored Aug 17, 2006 by unknown
17 changed files
--- a/sql/Makefile.am
+++ b/sql/Makefile.am
@@ -105,8 +105,8 @@ mysqld_SOURCES =	sql_lex.cc sql_handler.cc sql_partition.cc \
 			tztime.cc my_time.c my_user.c my_decimal.cc\
 			sp_head.cc sp_pcontext.cc  sp_rcontext.cc sp.cc \
 			sp_cache.cc parse_file.cc sql_trigger.cc \
-                        event_scheduler.cc events.cc event_data_objects.cc \
+                        event_scheduler.cc event_data_objects.cc \
-                        event_queue.cc event_db_repository.cc \
+                        event_queue.cc event_db_repository.cc events.cc \
 			sql_plugin.cc sql_binlog.cc \
 			sql_builtin.cc sql_tablespace.cc partition_info.cc

--- a/sql/event_data_objects.cc
+++ b/sql/event_data_objects.cc
@@ -59,19 +59,17 @@ Event_parse_data::new_instance(THD *thd)
 */
 Event_parse_data::Event_parse_data()
+  :on_completion(ON_COMPLETION_DROP), status(ENABLED),
+   item_starts(NULL), item_ends(NULL), item_execute_at(NULL),
+   starts_null(TRUE), ends_null(TRUE), execute_at_null(TRUE),
+   item_expression(NULL), expression(0)
 {
  DBUG_ENTER("Event_parse_data::Event_parse_data");
-  item_execute_at= item_expression= item_starts= item_ends= NULL;
-  status= ENABLED;
-  on_completion= ON_COMPLETION_DROP;
-  expression= 0;
  /* Actually in the parser STARTS is always set */
  set_zero_time(&starts, MYSQL_TIMESTAMP_DATETIME);
  set_zero_time(&ends, MYSQL_TIMESTAMP_DATETIME);
  set_zero_time(&execute_at, MYSQL_TIMESTAMP_DATETIME);
-  starts_null= ends_null= execute_at_null= TRUE;
  body.str= comment.str= NULL;
  body.length= comment.length= 0;
@@ -736,8 +734,8 @@ Event_timed::~Event_timed()
    Event_job_data::Event_job_data()
 */
-Event_job_data::Event_job_data():
+Event_job_data::Event_job_data()
-  thd(NULL), sphead(NULL), sql_mode(0)
+  :thd(NULL), sphead(NULL), sql_mode(0)
 {
 }
@@ -1115,14 +1113,16 @@ bool get_next_time(TIME *next, TIME *start, TIME *time_now, TIME *last_exec,
    interval.month= (diff_months / months)*months;
    /*
      Check if the same month as last_exec (always set - prerequisite)
-      An event happens at most once per month so there is no way to schedule
+      An event happens at most once per month so there is no way to
-      it two times for the current month. This saves us from two calls to
+      schedule it two times for the current month. This saves us from two
-      date_add_interval() if the event was just executed.  But if the scheduler
+      calls to date_add_interval() if the event was just executed.  But if
-      is started and there was at least 1 scheduled date skipped this one does
+      the scheduler is started and there was at least 1 scheduled date
-      not help and two calls to date_add_interval() will be done, which is a
+      skipped this one does not help and two calls to date_add_interval()
-      bit more expensive but compared to the rareness of the case is neglectable.
+      will be done, which is a bit more expensive but compared to the
+      rareness of the case is neglectable.
    */
-    if (time_now->year==last_exec->year && time_now->month==last_exec->month)
+    if (time_now->year == last_exec->year &&
+        time_now->month == last_exec->month)
      interval.month+= months;
    tmp= *start;
@@ -1454,7 +1454,8 @@ Event_queue_element::drop(THD *thd)
  RETURN VALUE
    FALSE   OK
-    TRUE    Error while opening mysql.event for writing or during write on disk
+    TRUE    Error while opening mysql.event for writing or during
+            write on disk
 */
 bool
@@ -1645,9 +1646,9 @@ Event_job_data::execute(THD *thd)
  event_change_security_context(thd, definer_user, definer_host, dbname,
                                &save_ctx);
  /*
-    THD::~THD will clean this or if there is DROP DATABASE in the SP then
+    THD::~THD will clean this or if there is DROP DATABASE in the
-    it will be free there. It should not point to our buffer which is allocated
+    SP then it will be free there. It should not point to our buffer
-    on a mem_root.
+    which is allocated on a mem_root.
  */
  thd->db= my_strdup(dbname.str, MYF(0));
  thd->db_length= dbname.length;
@@ -1719,7 +1720,6 @@ Event_job_data::compile(THD *thd, MEM_ROOT *mem_root)
  switch (get_fake_create_event(thd, &show_create)) {
  case EVEX_MICROSECOND_UNSUP:
-    sql_print_error("Scheduler");
    DBUG_RETURN(EVEX_MICROSECOND_UNSUP);
  case 0:
    break;
@@ -1769,7 +1769,8 @@ Event_job_data::compile(THD *thd, MEM_ROOT *mem_root)
      Free lex associated resources
      QQ: Do we really need all this stuff here?
    */
-    sql_print_error("error during compile of %s.%s or thd->is_fatal_error=%d",
+    sql_print_error("SCHEDULER: Error during compilation of %s.%s or "
+                    "thd->is_fatal_error=%d",
                    dbname.str, name.str, thd->is_fatal_error);
    lex.unit.cleanup();
@@ -1832,10 +1833,13 @@ event_basic_db_equal(LEX_STRING db, Event_basic *et)
 /*
-  Checks whether two events are equal by identifiers
+  Checks whether an event has equal `db` and `name`
  SYNOPSIS
    event_basic_identifier_equal()
+      db   Schema
+      name Name
+      et   The event object
  RETURN VALUE
    TRUE   Equal
@@ -1851,7 +1855,8 @@ event_basic_identifier_equal(LEX_STRING db, LEX_STRING name, Event_basic *b)
 /*
-  Switches the security context
+  Switches the security context.
  SYNOPSIS
    event_change_security_context()
      thd     Thread
@@ -1887,7 +1892,8 @@ event_change_security_context(THD *thd, LEX_STRING user, LEX_STRING host,
 /*
-  Restores the security context
+  Restores the security context.
  SYNOPSIS
    event_restore_security_context()
      thd     Thread

--- a/sql/event_data_objects.h
+++ b/sql/event_data_objects.h
@@ -237,7 +237,7 @@ class Event_parse_data : public Sql_alloc
  new_instance(THD *thd);
  bool
-  check_parse_data(THD *);
+  check_parse_data(THD *thd);
  void
  init_body(THD *thd);

--- a/sql/event_db_repository.cc
+++ b/sql/event_db_repository.cc
@@ -22,14 +22,12 @@
 #include "sp.h"
 #include "sp_head.h"
-#define EVEX_DB_FIELD_LEN 64
-#define EVEX_NAME_FIELD_LEN 64
+static
 time_t mysql_event_last_create_time= 0L;
 static
-TABLE_FIELD_W_TYPE event_table_fields[ET_FIELD_COUNT] =
+TABLE_FIELD_W_TYPE const event_table_fields[ET_FIELD_COUNT] =
 {
  {
    {(char *) STRING_WITH_LEN("db")},
@@ -250,18 +248,18 @@ mysql_event_fill_row(THD *thd, TABLE *table, Event_parse_data *et,
 /*
  Performs an index scan of event_table (mysql.event) and fills schema_table.
-  Synopsis
+  SYNOPSIS
    Event_db_repository::index_read_for_db_for_i_s()
      thd          Thread
      schema_table The I_S.EVENTS table
      event_table  The event table to use for loading (mysql.event)
-  Returns
+  RETURN VALUE
    0  OK
    1  Error
 */
-int
+bool
 Event_db_repository::index_read_for_db_for_i_s(THD *thd, TABLE *schema_table,
                                               TABLE *event_table, char *db)
 {
@@ -305,33 +303,34 @@ Event_db_repository::index_read_for_db_for_i_s(THD *thd, TABLE *schema_table,
  event_table->file->ha_index_end(); 
  /*  ret is guaranteed to be != 0 */
  if (ret == HA_ERR_END_OF_FILE || ret == HA_ERR_KEY_NOT_FOUND)
-    DBUG_RETURN(0);
+    DBUG_RETURN(FALSE);
-  DBUG_RETURN(1);
+  DBUG_RETURN(TRUE);
 }
 /*
  Performs a table scan of event_table (mysql.event) and fills schema_table.
-  Synopsis
+  SYNOPSIS
    Events_db_repository::table_scan_all_for_i_s()
      thd          Thread
      schema_table The I_S.EVENTS in memory table
      event_table  The event table to use for loading.
-  Returns
+  RETURN VALUE
-    0  OK
+    FALSE  OK
-    1  Error
+    TRUE   Error
 */
-int
+bool
 Event_db_repository::table_scan_all_for_i_s(THD *thd, TABLE *schema_table,
                                            TABLE *event_table)
 {
  int ret;
  READ_RECORD read_record_info;
  DBUG_ENTER("Event_db_repository::table_scan_all_for_i_s");
  init_read_record(&read_record_info, thd, event_table, NULL, 1, 0);
  /*
@@ -350,7 +349,7 @@ Event_db_repository::table_scan_all_for_i_s(THD *thd, TABLE *schema_table,
  end_read_record(&read_record_info);
  /*  ret is guaranteed to be != 0 */
-  DBUG_RETURN(ret == -1? 0:1);
+  DBUG_RETURN(ret == -1? FALSE:TRUE);
 }
@@ -358,15 +357,15 @@ Event_db_repository::table_scan_all_for_i_s(THD *thd, TABLE *schema_table,
  Fills I_S.EVENTS with data loaded from mysql.event. Also used by
  SHOW EVENTS
-  Synopsis
+  SYNOPSIS
    Event_db_repository::fill_schema_events()
      thd     Thread
      tables  The schema table
      db      If not NULL then get events only from this schema
-  Returns
+  RETURN VALUE
-    0  OK
+    FALSE  OK
-    1  Error
+    TRUE   Error
 */
 int
@@ -459,12 +458,12 @@ Event_db_repository::open_event_table(THD *thd, enum thr_lock_type lock_type,
  SYNOPSIS
    check_parse_params()
-       thd            THD
+      thd         Thread context
-       et             event's data
+      parse_data  Event's data
-   RETURNS
+  RETURN VALUE
-     0                OK
+    FALSE  OK
-     EVEX_BAD_PARAMS  Error (reported)
+    TRUE   Error (reported)
 */
 static int
@@ -504,7 +503,7 @@ check_parse_params(THD *thd, Event_parse_data *parse_data)
  SYNOPSIS
    Event_db_repository::create_event()
      thd             [in]  THD
-      et              [in]  Object containing info about the event
+      parse_data      [in]  Object containing info about the event
      create_if_not   [in]  Whether to generate anwarning in case event exists
      rows_affected   [out] How many rows were affected
@@ -517,7 +516,7 @@ check_parse_params(THD *thd, Event_parse_data *parse_data)
    ::update_event. The name of the event is inside "et".
 */
-int
+bool
 Event_db_repository::create_event(THD *thd, Event_parse_data *parse_data,
                                  my_bool create_if_not, uint *rows_affected)
 {
@@ -531,6 +530,9 @@ Event_db_repository::create_event(THD *thd, Event_parse_data *parse_data,
  DBUG_ENTER("Event_db_repository::create_event");
  *rows_affected= 0;
+  if (check_parse_params(thd, parse_data))
+    goto err;
  DBUG_PRINT("info", ("open mysql.event for update"));
  if (open_event_table(thd, TL_WRITE, &table))
  {
@@ -538,8 +540,6 @@ Event_db_repository::create_event(THD *thd, Event_parse_data *parse_data,
    goto err;
  }
-  if (check_parse_params(thd, parse_data))
-    goto err;
  DBUG_PRINT("info", ("name: %.*s", parse_data->name.length,
             parse_data->name.str));
@@ -570,16 +570,17 @@ Event_db_repository::create_event(THD *thd, Event_parse_data *parse_data,
  if (system_charset_info->cset->
        numchars(system_charset_info, parse_data->dbname.str,
-                 parse_data->dbname.str +
+                 parse_data->dbname.str + parse_data->dbname.length) >
-                 parse_data->dbname.length) > EVEX_DB_FIELD_LEN)
+      table->field[ET_FIELD_DB]->char_length())
  {
    my_error(ER_TOO_LONG_IDENT, MYF(0), parse_data->dbname.str);
    goto err;
  }
  if (system_charset_info->cset->
        numchars(system_charset_info, parse_data->name.str,
-                 parse_data->name.str +
+                 parse_data->name.str + parse_data->name.length) >
-                 parse_data->name.length) > EVEX_DB_FIELD_LEN)
+      table->field[ET_FIELD_NAME]->char_length())
  {
    my_error(ER_TOO_LONG_IDENT, MYF(0), parse_data->name.str);
    goto err;
@@ -622,36 +623,18 @@ Event_db_repository::create_event(THD *thd, Event_parse_data *parse_data,
  if (dbchanged)
    (void) mysql_change_db(thd, old_db.str, 1);
  /*
-    When valgrinded, the following call may lead to the following error:
+    This statement may cause a spooky valgrind warning at startup
+    inside init_key_cache on my system (ahristov, 2006/08/10) 
-    Syscall param pwrite64(buf) points to uninitialised byte(s)
-      at 0x406003B: do_pwrite64 (in /lib/tls/libpthread.so.0)
-      by 0x40600EF: pwrite64 (in /lib/tls/libpthread.so.0)
-      by 0x856FF74: my_pwrite (my_pread.c:146)
-      by 0x85734E1: flush_cached_blocks (mf_keycache.c:2280)
-    ....
-    Address 0x6618110 is 56 bytes inside a block of size 927,772 alloc'd
-     at 0x401C451: malloc (vg_replace_malloc.c:149)
-      by 0x8578CDC: _mymalloc (safemalloc.c:138)
-      by 0x858E5E2: my_large_malloc (my_largepage.c:65)
-      by 0x8570634: init_key_cache (mf_keycache.c:343)
-      by 0x82EDA51: ha_init_key_cache(char const*, st_key_cache*) (handler.cc:2509)
-      by 0x8212071: process_key_caches(int (*)(char const*, st_key_cache*))
-                                                                  (set_var.cc:3824)
-      by 0x8206D75: init_server_components() (mysqld.cc:3304)
-      by 0x8207163: main (mysqld.cc:3578)
-    I think it is safe not to think about it.
  */
  close_thread_tables(thd);
-  DBUG_RETURN(0);
+  DBUG_RETURN(FALSE);
 err:
  if (dbchanged)
    (void) mysql_change_db(thd, old_db.str, 1);
  if (table)
    close_thread_tables(thd);
-  DBUG_RETURN(EVEX_GENERAL_ERROR);
+  DBUG_RETURN(TRUE);
 }
@@ -665,8 +648,8 @@ Event_db_repository::create_event(THD *thd, Event_parse_data *parse_data,
      et       event's data
  RETURN VALUE
-    0  OK
+    FALSE  OK
-    EVEX_GENERAL_ERROR  Error occured and reported
+    TRUE   Error (reported)
  NOTES
    sp_name is passed since this is the name of the event to
@@ -679,7 +662,6 @@ Event_db_repository::update_event(THD *thd, Event_parse_data *parse_data,
 {
  CHARSET_INFO *scs= system_charset_info;
  TABLE *table= NULL;
-  int ret;
  DBUG_ENTER("Event_db_repository::update_event");
  if (open_event_table(thd, TL_WRITE, &table))
@@ -698,7 +680,7 @@ Event_db_repository::update_event(THD *thd, Event_parse_data *parse_data,
    DBUG_PRINT("info", ("rename to: %s@%s", new_dbname->str, new_name->str));
  /* first look whether we overwrite */
-  if (new_dbname)
+  if (new_name)
  {
    if (!sortcmp_lex_string(parse_data->name, *new_name, scs) &&
        !sortcmp_lex_string(parse_data->dbname, *new_dbname, scs))
@@ -747,9 +729,10 @@ Event_db_repository::update_event(THD *thd, Event_parse_data *parse_data,
  if (end_active_trans(thd))
    goto err;
-  if (table->file->ha_update_row(table->record[1], table->record[0]))
+  int res;
+  if ((res= table->file->ha_update_row(table->record[1], table->record[0])))
  {
-    my_error(ER_EVENT_STORE_FAILED, MYF(0), parse_data->name.str, ret);
+    my_error(ER_EVENT_STORE_FAILED, MYF(0), parse_data->name.str, res);
    goto err;
  }
@@ -887,16 +870,14 @@ Event_db_repository::find_named_event(THD *thd, LEX_STRING db, LEX_STRING name,
    Event_db_repository::drop_schema_events()
      thd     Thread
      schema  The database to clean from events
-  RETURN VALUE
-    0  OK
-   !0  Error (Reported)
 */
-int
+void
 Event_db_repository::drop_schema_events(THD *thd, LEX_STRING schema)
 {
-  return drop_events_by_field(thd, ET_FIELD_DB, schema);
+  DBUG_ENTER("Event_db_repository::drop_schema_events");
+  drop_events_by_field(thd, ET_FIELD_DB, schema);
+  DBUG_VOID_RETURN;
 }
@@ -909,28 +890,29 @@ Event_db_repository::drop_schema_events(THD *thd, LEX_STRING schema)
      table       mysql.event TABLE
      field       Which field of the row to use for matching
      field_value The value that should match
-  RETURN VALUE
-     0  OK
-    !0  Error from ha_delete_row
 */
-int
+void
 Event_db_repository::drop_events_by_field(THD *thd,  
                                          enum enum_events_table_field field,
                                          LEX_STRING field_value)
 {
  int ret= 0;
  TABLE *table= NULL;
-  Open_tables_state backup;
  READ_RECORD read_record_info;
  DBUG_ENTER("Event_db_repository::drop_events_by_field");  
  DBUG_PRINT("enter", ("field=%d field_value=%s", field, field_value.str));
  if (open_event_table(thd, TL_WRITE, &table))
  {
+    /*
+      Currently being used only for DROP DATABASE - In this case we don't need
+      error message since the OK packet has been sent. But for DROP USER we
+      could need it.
      my_error(ER_EVENT_OPEN_TABLE_FAILED, MYF(0));
-    DBUG_RETURN(1);
+    */
+    DBUG_VOID_RETURN;
  }
  /* only enabled events are in memory, so we go now and delete the rest */
@@ -939,22 +921,20 @@ Event_db_repository::drop_events_by_field(THD *thd,
  {
    char *et_field= get_field(thd->mem_root, table->field[field]);
-    LEX_STRING et_field_lex= {et_field, strlen(et_field)};
+    LEX_STRING et_field_lex= { et_field, strlen(et_field) };
    DBUG_PRINT("info", ("Current event %s name=%s", et_field,
               get_field(thd->mem_root, table->field[ET_FIELD_NAME])));
    if (!sortcmp_lex_string(et_field_lex, field_value, system_charset_info))
    {
      DBUG_PRINT("info", ("Dropping"));
-      if ((ret= table->file->ha_delete_row(table->record[0])))
+      ret= table->file->ha_delete_row(table->record[0]);
-        my_error(ER_EVENT_DROP_FAILED, MYF(0),
-                 get_field(thd->mem_root, table->field[ET_FIELD_NAME]));
    }
  }
  end_read_record(&read_record_info);
-  thd->version--;   /* Force close to free memory */
+  close_thread_tables(thd);
-  DBUG_RETURN(ret);
+  DBUG_VOID_RETURN;
 }
@@ -964,10 +944,10 @@ Event_db_repository::drop_events_by_field(THD *thd,
  SYNOPSIS
    Event_db_repository::load_named_event()
-      thd      [in]  THD
+      thd      [in]  Thread context
      dbname   [in]  Event's db name
      name     [in]  Event's name
-      etn_new  [out] The loaded event
+      etn      [out] The loaded event
  RETURN VALUE
    FALSE  OK

--- a/sql/event_db_repository.h
+++ b/sql/event_db_repository.h
@@ -47,9 +47,6 @@ events_table_index_read_for_db(THD *thd, TABLE *schema_table,
 int
 events_table_scan_all(THD *thd, TABLE *schema_table, TABLE *event_table);
-int
-fill_schema_events(THD *thd, TABLE_LIST *tables, COND * /* cond */);
 class Event_basic;
 class Event_parse_data;
@@ -58,7 +55,7 @@ class Event_db_repository
 public:
  Event_db_repository(){}
-  int
+  bool
  create_event(THD *thd, Event_parse_data *parse_data, my_bool create_if_not,
               uint *rows_affected);
@@ -70,7 +67,7 @@ class Event_db_repository
  drop_event(THD *thd, LEX_STRING db, LEX_STRING name, bool drop_if_exists,
             uint *rows_affected);
-  int
+  void
  drop_schema_events(THD *thd, LEX_STRING schema);
  bool
@@ -79,7 +76,6 @@ class Event_db_repository
  bool
  load_named_event(THD *thd, LEX_STRING dbname, LEX_STRING name, Event_basic *et);
  int
  open_event_table(THD *thd, enum thr_lock_type lock_type, TABLE **table);
@@ -87,14 +83,14 @@ class Event_db_repository
  fill_schema_events(THD *thd, TABLE_LIST *tables, char *db);
 private:
-  int
+  void
  drop_events_by_field(THD *thd, enum enum_events_table_field field,
                       LEX_STRING field_value);
-  int
+  bool
  index_read_for_db_for_i_s(THD *thd, TABLE *schema_table, TABLE *event_table,
                            char *db);
-  int
+  bool
  table_scan_all_for_i_s(THD *thd, TABLE *schema_table, TABLE *event_table);
  static bool

--- a/sql/event_queue.cc
+++ b/sql/event_queue.cc
@@ -73,35 +73,6 @@ event_queue_element_compare_q(void *vptr, byte* a, byte *b)
 }
-pthread_handler_t
-event_queue_loader_thread(void *arg)
-{
-  /* needs to be first for thread_stack */
-  THD *thd= (THD *)((struct event_queue_param *) arg)->thd;
-  struct event_queue_param *param= (struct event_queue_param *) arg;
-  thd->thread_stack= (char *) &thd;
-  if (post_init_event_thread(thd))
-    goto end;
-  DBUG_ENTER("event_queue_loader_thread");
-  pthread_mutex_lock(&param->LOCK_loaded);
-  param->queue->check_system_tables(thd);
-  param->queue->load_events_from_db(thd);
-  param->loading_finished= TRUE;
-  pthread_cond_signal(&param->COND_loaded);
-  pthread_mutex_unlock(&param->LOCK_loaded);
-end:
-  deinit_event_thread(thd);
-  DBUG_RETURN(0);                               // Against gcc warnings
-}
 /*
  Constructor of class Event_queue.
@@ -110,14 +81,12 @@ event_queue_loader_thread(void *arg)
 */
 Event_queue::Event_queue()
+  :mutex_last_unlocked_at_line(0), mutex_last_locked_at_line(0),
+   mutex_last_attempted_lock_at_line(0),
+   mutex_queue_data_locked(FALSE), mutex_queue_data_attempting_lock(FALSE)
 {
-  mutex_last_unlocked_at_line= mutex_last_locked_at_line=
-    mutex_last_attempted_lock_at_line= 0;
  mutex_last_unlocked_in_func= mutex_last_locked_in_func=
    mutex_last_attempted_lock_in_func= "";
-  mutex_queue_data_locked= mutex_queue_data_attempting_lock= FALSE;
 }
@@ -150,7 +119,12 @@ Event_queue::deinit_mutexes()
 /*
-  Inits the queue
+  This is a queue's constructor. Until this method is called, the
+  queue is unusable.  We don't use a C++ constructor instead in
+  order to be able to check the return value. The queue is
+  initialized once at server startup.  Initialization can fail in
+  case of a failure reading events from the database or out of
+  memory.
  SYNOPSIS
    Event_queue::init()
@@ -161,9 +135,9 @@ Event_queue::deinit_mutexes()
 */
 bool
-Event_queue::init_queue(Event_db_repository *db_repo, Event_scheduler *sched)
+Event_queue::init_queue(THD *thd, Event_db_repository *db_repo,
+                        Event_scheduler *sched)
 {
-  THD *new_thd;
  pthread_t th;
  bool res;
  struct event_queue_param *event_queue_param_value= NULL;
@@ -186,43 +160,16 @@ Event_queue::init_queue(Event_db_repository *db_repo, Event_scheduler *sched)
  if (sizeof(my_time_t) != sizeof(time_t))
  {
    sql_print_error("SCHEDULER: sizeof(my_time_t) != sizeof(time_t) ."
-                    "The scheduler may not work correctly. Stopping.");
+                    "The scheduler may not work correctly. Stopping");
    DBUG_ASSERT(0);
    goto err;
  }
-  if (!(new_thd= new THD))
+  res= load_events_from_db(thd);
-    goto err;
-  pre_init_event_thread(new_thd);
-  new_thd->security_ctx->set_user((char*)"event_scheduler_loader");
-  event_queue_param_value= (struct event_queue_param *)
-                          my_malloc(sizeof(struct event_queue_param), MYF(0));
-  event_queue_param_value->thd= new_thd;
-  event_queue_param_value->queue= this;
-  event_queue_param_value->loading_finished= FALSE;
-  pthread_mutex_init(&event_queue_param_value->LOCK_loaded, MY_MUTEX_INIT_FAST);
-  pthread_cond_init(&event_queue_param_value->COND_loaded, NULL);
-  pthread_mutex_lock(&event_queue_param_value->LOCK_loaded);
-  DBUG_PRINT("info", ("Forking new thread for scheduduler. THD=0x%lx", new_thd));
-  if (!(res= pthread_create(&th, &connection_attrib, event_queue_loader_thread,
-                            (void*)event_queue_param_value)))
-  {
-    do {
-      pthread_cond_wait(&event_queue_param_value->COND_loaded,
-                        &event_queue_param_value->LOCK_loaded);
-    } while (event_queue_param_value->loading_finished == FALSE);
-  }
-  pthread_mutex_unlock(&event_queue_param_value->LOCK_loaded);
-  pthread_mutex_destroy(&event_queue_param_value->LOCK_loaded);
-  pthread_cond_destroy(&event_queue_param_value->COND_loaded);
-  my_free((char *)event_queue_param_value, MYF(0));
  UNLOCK_QUEUE_DATA();
+  if (res)
+    deinit_queue();
  DBUG_RETURN(res);
 err:
@@ -316,16 +263,15 @@ Event_queue::update_event(THD *thd, LEX_STRING dbname, LEX_STRING name,
                          LEX_STRING *new_schema, LEX_STRING *new_name)
 {
  int res;
-  Event_queue_element *old_element= NULL,
+  Event_queue_element *new_element;
-                      *new_element;
  DBUG_ENTER("Event_queue::update_event");
  DBUG_PRINT("enter", ("thd=0x%lx et=[%s.%s]", thd, dbname.str, name.str));
  new_element= new Event_queue_element();
-  res= db_repository->load_named_event(thd, new_schema? *new_schema:dbname,
+  res= db_repository->load_named_event(thd, new_schema ? *new_schema:dbname,
-                                       new_name? *new_name:name, new_element);
+                                       new_name ? *new_name:name, new_element);
  if (res)
  {
    delete new_element;
@@ -345,16 +291,12 @@ Event_queue::update_event(THD *thd, LEX_STRING dbname, LEX_STRING name,
    new_element->compute_next_execution_time();
  LOCK_QUEUE_DATA();
-  if (!(old_element= find_n_remove_event(dbname, name)))
+  find_n_remove_event(dbname, name);
-  {
-    DBUG_PRINT("info", ("%s.%s not cached, probably was DISABLED",
-                        dbname.str, name.str));
-  }
  /* If not disabled event */
  if (new_element)
  {
-    DBUG_PRINT("info", ("new event in the Q 0x%lx old 0x%lx",
+    DBUG_PRINT("info", ("new event in the Q 0x%lx", new_element));
-                        new_element, old_element));
    queue_insert_safe(&queue, (byte *) new_element);
  }
  dbug_dump_queue(thd->query_start());
@@ -363,8 +305,6 @@ Event_queue::update_event(THD *thd, LEX_STRING dbname, LEX_STRING name,
  if (new_element)
    notify_observers();
-  if (old_element)
-    delete old_element;
 end:
  DBUG_PRINT("info", ("res=%d", res));
  DBUG_RETURN(res);
@@ -385,20 +325,14 @@ void
 Event_queue::drop_event(THD *thd, LEX_STRING dbname, LEX_STRING name)
 {
  int res;
-  Event_queue_element *element;
  DBUG_ENTER("Event_queue::drop_event");
  DBUG_PRINT("enter", ("thd=0x%lx name=0x%lx", thd, name));
  LOCK_QUEUE_DATA();
-  element= find_n_remove_event(dbname, name);
+  find_n_remove_event(dbname, name);
  dbug_dump_queue(thd->query_start());
  UNLOCK_QUEUE_DATA();
-  if (element)
-    delete element;
-  else
-    DBUG_PRINT("info", ("No such event found, probably DISABLED"));
  /*
    We don't signal here because the scheduler will catch the change
    next time it wakes up.
@@ -429,10 +363,10 @@ void
 Event_queue::drop_matching_events(THD *thd, LEX_STRING pattern,
                           bool (*comparator)(LEX_STRING, Event_basic *))
 {
+  uint i= 0;
  DBUG_ENTER("Event_queue::drop_matching_events");
  DBUG_PRINT("enter", ("pattern=%s", pattern.str));
-  uint i= 0;
  while (i < queue.elements)
  {
    Event_queue_element *et= (Event_queue_element *) queue_element(&queue, i);
@@ -440,10 +374,10 @@ Event_queue::drop_matching_events(THD *thd, LEX_STRING pattern,
    if (comparator(pattern, et))
    {
      /*
-        The queue is ordered. If we remove an element, then all elements after
+        The queue is ordered. If we remove an element, then all elements
-        it will shift one position to the left, if we imagine it as an array
+        after it will shift one position to the left, if we imagine it as
-        from left to the right. In this case we should not increment the 
+        an array from left to the right. In this case we should not
-        counter and the (i < queue.elements) condition is ok.
+        increment the counter and the (i < queue.elements) condition is ok.
      */
      queue_remove(&queue, i);
      delete et;
@@ -453,12 +387,12 @@ Event_queue::drop_matching_events(THD *thd, LEX_STRING pattern,
  }
  /*
    We don't call notify_observers() . If we remove the top event:
-    1. The queue is empty. The scheduler will wake up at some time and realize
+    1. The queue is empty. The scheduler will wake up at some time and
-       that the queue is empty. If create_event() comes inbetween it will
+       realize that the queue is empty. If create_event() comes inbetween
-       signal the scheduler
+       it will signal the scheduler
-    2. The queue is not empty, but the next event after the previous top, won't
+    2. The queue is not empty, but the next event after the previous top,
-       be executed any time sooner than the element we removed. Hence, we may
+       won't be executed any time sooner than the element we removed. Hence,
-       not notify the scheduler and it will realize the change when it
+       we may not notify the scheduler and it will realize the change when it
       wakes up from timedwait.
  */
@@ -472,11 +406,8 @@ Event_queue::drop_matching_events(THD *thd, LEX_STRING pattern,
  SYNOPSIS
    Event_queue::drop_schema_events()
-      thd        THD
+      thd        HD
-      db         The schema name
+      schema    The schema name
-  RETURN VALUE
-    >=0  Number of dropped events
 */
 void
@@ -516,16 +447,12 @@ Event_queue::notify_observers()
      db    The schema of the event to find
      name  The event to find
-  RETURN VALUE
-    NULL       Not found
-    otherwise  Address
  NOTE
    The caller should do the locking also the caller is responsible for
    actual signalling in case an event is removed from the queue.
 */
-Event_queue_element *
+void
 Event_queue::find_n_remove_event(LEX_STRING db, LEX_STRING name)
 {
  uint i;
@@ -539,11 +466,12 @@ Event_queue::find_n_remove_event(LEX_STRING db, LEX_STRING name)
    if (event_basic_identifier_equal(db, name, et))
    {
      queue_remove(&queue, i);
-      DBUG_RETURN(et);
+      delete et;
+      break;
    }
  }
-  DBUG_RETURN(NULL);
+  DBUG_VOID_RETURN;
 }
@@ -583,7 +511,7 @@ Event_queue::load_events_from_db(THD *thd)
  if ((ret= db_repository->open_event_table(thd, TL_READ, &table)))
  {
-    sql_print_error("SCHEDULER: Table mysql.event is damaged. Can not open.");
+    sql_print_error("SCHEDULER: Table mysql.event is damaged. Can not open");
    DBUG_RETURN(EVEX_OPEN_TABLE_FAILED);
  }
@@ -625,14 +553,17 @@ Event_queue::load_events_from_db(THD *thd)
      temp_job_data.load_from_row(table);
-      /* We load only on scheduler root just to check whether the body compiles */
+      /*
+        We load only on scheduler root just to check whether the body
+        compiles.
+      */
      switch (ret= temp_job_data.compile(thd, thd->mem_root)) {
      case EVEX_MICROSECOND_UNSUP:
        sql_print_error("SCHEDULER: mysql.event is tampered. MICROSECOND is not "
                        "supported but found in mysql.event");
        break;
      case EVEX_COMPILE_ERROR:
-        sql_print_error("SCHEDULER: Error while compiling %s.%s. Aborting load.",
+        sql_print_error("SCHEDULER: Error while compiling %s.%s. Aborting load",
                        et->dbname.str, et->name.str);
        break;
      default:
@@ -663,12 +594,10 @@ Event_queue::load_events_from_db(THD *thd)
  else
  {
    ret= 0;
-    sql_print_information("SCHEDULER: Loaded %d event%s", count, (count == 1)?"":"s");
+    sql_print_information("SCHEDULER: Loaded %d event%s", count,
+                          (count == 1)?"":"s");
  }
-  /* Force close to free memory */
-  thd->version--;
  close_thread_tables(thd);
  DBUG_PRINT("info", ("Status code %d. Loaded %d event(s)", ret, count));
@@ -676,71 +605,6 @@ Event_queue::load_events_from_db(THD *thd)
 }
-/*
-  Opens mysql.db and mysql.user and checks whether:
-    1. mysql.db has column Event_priv at column 20 (0 based);
-    2. mysql.user has column Event_priv at column 29 (0 based);
-  SYNOPSIS
-    Event_queue::check_system_tables()
-      thd  Thread
-  RETURN VALUE
-    FALSE  OK
-    TRUE   Error
-*/
-void
-Event_queue::check_system_tables(THD *thd)
-{
-  TABLE_LIST tables;
-  bool not_used;
-  Open_tables_state backup;
-  bool ret;
-  DBUG_ENTER("Event_queue::check_system_tables");
-  DBUG_PRINT("enter", ("thd=0x%lx", thd));
-  thd->reset_n_backup_open_tables_state(&backup);
-  bzero((char*) &tables, sizeof(tables));
-  tables.db= (char*) "mysql";
-  tables.table_name= tables.alias= (char*) "db";
-  tables.lock_type= TL_READ;
-  if ((ret= simple_open_n_lock_tables(thd, &tables)))
-  {
-    sql_print_error("Cannot open mysql.db");
-    goto end;
-  }
-  ret= table_check_intact(tables.table, MYSQL_DB_FIELD_COUNT,
-                          mysql_db_table_fields, &mysql_db_table_last_check,
-                          ER_CANNOT_LOAD_FROM_TABLE);
-  close_thread_tables(thd);
-  bzero((char*) &tables, sizeof(tables));
-  tables.db= (char*) "mysql";
-  tables.table_name= tables.alias= (char*) "user";
-  tables.lock_type= TL_READ;
-  if (simple_open_n_lock_tables(thd, &tables))
-    sql_print_error("Cannot open mysql.db");
-  else
-  {
-    if (tables.table->s->fields < 29 ||
-        strncmp(tables.table->field[29]->field_name,
-                STRING_WITH_LEN("Event_priv")))
-      sql_print_error("mysql.user has no `Event_priv` column at position 29");
-    close_thread_tables(thd);
-  }
-end:
-  thd->restore_backup_open_tables_state(&backup);
-  DBUG_VOID_RETURN;
-}
 /*
  Recalculates activation times in the queue. There is one reason for
  that. Because the values (execute_at) by which the queue is ordered are

--- a/sql/event_queue.h
+++ b/sql/event_queue.h
@@ -36,7 +36,7 @@ class Event_queue
  deinit_mutexes();
  bool
-  init_queue(Event_db_repository *db_repo, Event_scheduler *sched);
+  init_queue(THD *thd, Event_db_repository *db_repo, Event_scheduler *sched);
  void
  deinit_queue();
@@ -56,9 +56,6 @@ class Event_queue
  void
  drop_schema_events(THD *thd, LEX_STRING schema);
-  void
-  check_system_tables(THD *thd);
  void
  recalculate_activation_times(THD *thd);
@@ -72,7 +69,7 @@ class Event_queue
  load_events_from_db(THD *thd);
 protected:
-  Event_queue_element *
+  void
  find_n_remove_event(LEX_STRING db, LEX_STRING name);

--- a/sql/event_scheduler.cc
+++ b/sql/event_scheduler.cc
@@ -384,7 +384,7 @@ Event_scheduler::start()
  if (!(new_thd= new THD))
  {
-    sql_print_error("SCHEDULER: Cannot init manager event thread.");
+    sql_print_error("SCHEDULER: Cannot init manager event thread");
    ret= TRUE;
    goto end;
  }
@@ -441,7 +441,7 @@ Event_scheduler::start()
 bool
 Event_scheduler::run(THD *thd)
 {
-  int res;
+  int res= FALSE;
  struct timespec abstime;
  Event_job_data *job_data;
  DBUG_ENTER("Event_scheduler::run");
@@ -464,7 +464,7 @@ Event_scheduler::run(THD *thd)
                                             &job_data, &abstime))
    {
      sql_print_information("SCHEDULER: Serious error during getting next"
-                            " event to execute. Stopping.");
+                            " event to execute. Stopping");
      break;
    }
@@ -532,7 +532,7 @@ Event_scheduler::execute_top(THD *thd, Event_job_data *job_data)
  pthread_t th;
  int res= 0;
  DBUG_ENTER("Event_scheduler::execute_top");
-  if (!(new_thd= new THD))
+  if (!(new_thd= new THD()))
    goto error;
  pre_init_event_thread(new_thd);

--- a/sql/event_scheduler.h
+++ b/sql/event_scheduler.h
@@ -31,12 +31,13 @@ deinit_event_thread(THD *thd);
 class Event_scheduler
 {
 public:
-  Event_scheduler(){}
+  Event_scheduler():state(UNINITIALIZED){}
  ~Event_scheduler(){}
  enum enum_state
  {
-    INITIALIZED = 0,
+    UNINITIALIZED = 0,
+    INITIALIZED,
    RUNNING,
    STOPPING
  };

--- a/sql/events.cc
+++ b/sql/events.cc
@@ -70,6 +70,15 @@ TYPELIB Events::opt_typelib=
  NULL
 };
+static
+Event_queue events_event_queue;
+static
+Event_scheduler events_event_scheduler;
+static
+Event_db_repository events_event_db_repository;
 Events Events::singleton;
 ulong Events::opt_event_scheduler= 2;
@@ -247,6 +256,22 @@ Events::reconstruct_interval_expression(String *buf, interval_type interval,
  return 0;
 }
+/*
+  Constructor of Events class. It's called when events.o
+  is loaded. Assigning addressed of static variables in this
+  object file.
+  SYNOPSIS
+    Events::Events()
+*/
+Events::Events()
+{
+  scheduler=     &events_event_scheduler;
+  event_queue=   &events_event_queue;
+  db_repository= &events_event_db_repository;
+}
 /*
  Opens mysql.event table with specified lock
@@ -277,25 +302,30 @@ Events::open_event_table(THD *thd, enum thr_lock_type lock_type,
  SYNOPSIS
    Events::create_event()
      thd            [in]  THD
-      et             [in]  Event's data from parsing stage
+      parse_data     [in]  Event's data from parsing stage
      if_not_exists  [in]  Whether IF NOT EXISTS was specified in the DDL
      rows_affected  [out] How many rows were affected
  RETURN VALUE
-    0   OK
+    FALSE  OK
-    !0  Error (Reported)
+    TRUE   Error (Reported)
  NOTES
    In case there is an event with the same name (db) and 
    IF NOT EXISTS is specified, an warning is put into the stack.
 */
-int
+bool
 Events::create_event(THD *thd, Event_parse_data *parse_data, bool if_not_exists,
                     uint *rows_affected)
 {
  int ret;
  DBUG_ENTER("Events::create_event");
+  if (unlikely(check_system_tables_error))
+  {
+    my_error(ER_EVENTS_DB_ERROR, MYF(0));
+    DBUG_RETURN(TRUE);
+  }
  pthread_mutex_lock(&LOCK_event_metadata);
  /* On error conditions my_error() is called so no need to handle here */
@@ -321,13 +351,13 @@ Events::create_event(THD *thd, Event_parse_data *parse_data, bool if_not_exists,
  SYNOPSIS
    Events::update_event()
      thd           [in]  THD
-      et            [in]  Event's data from parsing stage
+      parse_data    [in]  Event's data from parsing stage
      rename_to     [in]  Set in case of RENAME TO.
      rows_affected [out] How many rows were affected.
  RETURN VALUE
-    0   OK
+    FALSE  OK
-    !0  Error
+    TRUE   Error
  NOTES
    et contains data about dbname and event name. 
@@ -335,14 +365,19 @@ Events::create_event(THD *thd, Event_parse_data *parse_data, bool if_not_exists,
    that RENAME TO was specified in the query
 */
-int
+bool
 Events::update_event(THD *thd, Event_parse_data *parse_data, sp_name *rename_to,
                     uint *rows_affected)
 {
  int ret;
  DBUG_ENTER("Events::update_event");
-  LEX_STRING *new_dbname= rename_to? &rename_to->m_db: NULL;
+  LEX_STRING *new_dbname= rename_to ? &rename_to->m_db : NULL;
-  LEX_STRING *new_name= rename_to? &rename_to->m_name: NULL;
+  LEX_STRING *new_name= rename_to ? &rename_to->m_name : NULL;
+  if (unlikely(check_system_tables_error))
+  {
+    my_error(ER_EVENTS_DB_ERROR, MYF(0));
+    DBUG_RETURN(TRUE);
+  }
  pthread_mutex_lock(&LOCK_event_metadata);
  /* On error conditions my_error() is called so no need to handle here */
@@ -378,16 +413,21 @@ Events::update_event(THD *thd, Event_parse_data *parse_data, sp_name *rename_to,
                            removal from memory queue.
  RETURN VALUE
-     0  OK
+    FALSE  OK
-    !0  Error (reported)
+    TRUE   Error (reported)
 */
-int
+bool
 Events::drop_event(THD *thd, LEX_STRING dbname, LEX_STRING name, bool if_exists,
                   uint *rows_affected, bool only_from_disk)
 {
  int ret;
  DBUG_ENTER("Events::drop_event");
+  if (unlikely(check_system_tables_error))
+  {
+    my_error(ER_EVENTS_DB_ERROR, MYF(0));
+    DBUG_RETURN(TRUE);
+  }
  pthread_mutex_lock(&LOCK_event_metadata);
  /* On error conditions my_error() is called so no need to handle here */
@@ -409,27 +449,27 @@ Events::drop_event(THD *thd, LEX_STRING dbname, LEX_STRING name, bool if_exists,
    Events::drop_schema_events()
      thd  Thread
      db   ASCIIZ schema name
-  RETURN VALUE
-    0   OK
-    !0  Error
 */
-int
+void
 Events::drop_schema_events(THD *thd, char *db)
 {
-  int ret= 0;
+  LEX_STRING const db_lex= { db, strlen(db) };
-  LEX_STRING db_lex= {db, strlen(db)};
  DBUG_ENTER("Events::drop_schema_events");  
  DBUG_PRINT("enter", ("dropping events from %s", db));
+  if (unlikely(check_system_tables_error))
+  {
+    my_error(ER_EVENTS_DB_ERROR, MYF(0));
+    DBUG_VOID_RETURN;
+  }
  pthread_mutex_lock(&LOCK_event_metadata);
  event_queue->drop_schema_events(thd, db_lex);
-  ret= db_repository->drop_schema_events(thd, db_lex);
+  db_repository->drop_schema_events(thd, db_lex);
  pthread_mutex_unlock(&LOCK_event_metadata);
-  DBUG_RETURN(ret);
+  DBUG_VOID_RETURN;
 }
@@ -438,15 +478,15 @@ Events::drop_schema_events(THD *thd, char *db)
  SYNOPSIS
    Events::show_create_event()
-      thd        THD
+      thd   Thread context
-      spn        the name of the event (db, name)
+      spn   The name of the event (db, name)
  RETURN VALUE
-    0  OK
+    FALSE  OK
-    1  Error during writing to the wire
+    TRUE   Error during writing to the wire
 */
-int
+bool
 Events::show_create_event(THD *thd, LEX_STRING dbname, LEX_STRING name)
 {
  CHARSET_INFO *scs= system_charset_info;
@@ -455,6 +495,11 @@ Events::show_create_event(THD *thd, LEX_STRING dbname, LEX_STRING name)
  DBUG_ENTER("Events::show_create_event");
  DBUG_PRINT("enter", ("name: %s@%s", dbname.str, name.str));
+  if (unlikely(check_system_tables_error))
+  {
+    my_error(ER_EVENTS_DB_ERROR, MYF(0));
+    DBUG_RETURN(TRUE);
+  }
  ret= db_repository->load_named_event(thd, dbname, name, et);
@@ -481,8 +526,8 @@ Events::show_create_event(THD *thd, LEX_STRING dbname, LEX_STRING name)
    field_list.push_back(new Item_empty_string("sql_mode", sql_mode_len));
-    field_list.
+    field_list.push_back(new Item_empty_string("Create Event",
-        push_back(new Item_empty_string("Create Event", show_str.length()));
+                                               show_str.length()));
    if (protocol->send_fields(&field_list, Protocol::SEND_NUM_ROWS |
                                           Protocol::SEND_EOF))
@@ -501,7 +546,7 @@ Events::show_create_event(THD *thd, LEX_STRING dbname, LEX_STRING name)
  DBUG_RETURN(ret);
 err:
  delete et;
-  DBUG_RETURN(1);
+  DBUG_RETURN(TRUE);
 }
@@ -511,7 +556,7 @@ Events::show_create_event(THD *thd, LEX_STRING dbname, LEX_STRING name)
  SYNOPSIS
    Events::fill_schema_events()
-      thd     Thread
+      thd     Thread context
      tables  The schema table
      cond    Unused
@@ -525,6 +570,13 @@ Events::fill_schema_events(THD *thd, TABLE_LIST *tables, COND * /* cond */)
 {
  char *db= NULL;
  DBUG_ENTER("Events::fill_schema_events");
+  Events *myself= get_instance();
+  if (unlikely(myself->check_system_tables_error))
+  {
+    my_error(ER_EVENTS_DB_ERROR, MYF(0));
+    DBUG_RETURN(TRUE);
+  }
  /*
    If it's SHOW EVENTS then thd->lex->select_lex.db is guaranteed not to
    be NULL. Let's do an assert anyway.
@@ -537,8 +589,7 @@ Events::fill_schema_events(THD *thd, TABLE_LIST *tables, COND * /* cond */)
      DBUG_RETURN(1);
    db= thd->lex->select_lex.db;
  }
-  DBUG_RETURN(get_instance()->db_repository->
+  DBUG_RETURN(myself->db_repository->fill_schema_events(thd, tables, db));
-                                      fill_schema_events(thd, tables, db));
 }
@@ -552,31 +603,60 @@ Events::fill_schema_events(THD *thd, TABLE_LIST *tables, COND * /* cond */)
    This function is not synchronized.
  RETURN VALUE
-    0  OK
+    FALSE  OK
-    1  Error in case the scheduler can't start
+    TRUE   Error in case the scheduler can't start
 */
 bool
 Events::init()
 {
-  int res;
+  THD *thd;
+  bool res= FALSE;
  DBUG_ENTER("Events::init");
-  if (event_queue->init_queue(db_repository, scheduler))
+  /* We need a temporary THD during boot */
+  if (!(thd= new THD()))
  {
-    sql_print_information("SCHEDULER: Error while loading from disk.");
+    res= TRUE;
-    DBUG_RETURN(TRUE);
+    goto end;
+  }
+  /*
+    The thread stack does not start from this function but we cannot
+    guess the real value. So better some value that doesn't assert than
+    no value.
+  */
+  thd->thread_stack= (char*) &thd;
+  thd->store_globals();
+  if (check_system_tables(thd))
+  {
+    check_system_tables_error= TRUE;
+    sql_print_error("SCHEDULER: The system tables are damaged. "
+                    "The scheduler subsystem will be unusable during this run.");
+    goto end;
+  }
+  check_system_tables_error= FALSE;
+  if (event_queue->init_queue(thd, db_repository, scheduler))
+  {
+    sql_print_error("SCHEDULER: Error while loading from disk.");
+    goto end;
  }
  scheduler->init_scheduler(event_queue);
-  /* it should be an assignment! */
  if (opt_event_scheduler)
  {
    DBUG_ASSERT(opt_event_scheduler == 1 || opt_event_scheduler == 2);
    if (opt_event_scheduler == 1)
-      DBUG_RETURN(scheduler->start());
+      res= scheduler->start();
  }
-  DBUG_RETURN(FALSE);
+end:
+  delete thd;
+  /* Remember that we don't have a THD */
+  my_pthread_setspecific_ptr(THR_THD,  NULL);
+  DBUG_RETURN(res);
 }
@@ -595,10 +675,13 @@ Events::deinit()
 {
  DBUG_ENTER("Events::deinit");
+  if (likely(!check_system_tables_error))
+  {
    scheduler->stop();
    scheduler->deinit_scheduler();
    event_queue->deinit_queue();
+  }
  DBUG_VOID_RETURN;
 }
@@ -616,13 +699,7 @@ void
 Events::init_mutexes()
 {
  pthread_mutex_init(&LOCK_event_metadata, MY_MUTEX_INIT_FAST);
-  db_repository= new Event_db_repository;
-  event_queue= new Event_queue;
  event_queue->init_mutexes();
-  scheduler= new Event_scheduler;
  scheduler->init_mutexes();
 }
@@ -639,11 +716,6 @@ Events::destroy_mutexes()
 {
  event_queue->deinit_mutexes();
  scheduler->deinit_mutexes();
-  delete scheduler;
-  delete db_repository;
-  delete event_queue;
  pthread_mutex_destroy(&LOCK_event_metadata);
 }
@@ -700,6 +772,11 @@ bool
 Events::start_execution_of_events()
 {
  DBUG_ENTER("Events::start_execution_of_events");
+  if (unlikely(check_system_tables_error))
+  {
+    my_error(ER_EVENTS_DB_ERROR, MYF(0));
+    DBUG_RETURN(TRUE);
+  }
  DBUG_RETURN(scheduler->start());
 }
@@ -721,6 +798,11 @@ bool
 Events::stop_execution_of_events()
 {
  DBUG_ENTER("Events::stop_execution_of_events");
+  if (unlikely(check_system_tables_error))
+  {
+    my_error(ER_EVENTS_DB_ERROR, MYF(0));
+    DBUG_RETURN(TRUE);
+  }
  DBUG_RETURN(scheduler->stop());
 }
@@ -737,8 +819,86 @@ Events::stop_execution_of_events()
 */
 bool
-Events::is_started()
+Events::is_execution_of_events_started()
 {
-  DBUG_ENTER("Events::is_started");
+  DBUG_ENTER("Events::is_execution_of_events_started");
+  if (unlikely(check_system_tables_error))
+  {
+    my_error(ER_EVENTS_DB_ERROR, MYF(0));
+    DBUG_RETURN(FALSE);
+  }
  DBUG_RETURN(scheduler->get_state() == Event_scheduler::RUNNING);
 }
+/*
+  Opens mysql.db and mysql.user and checks whether:
+    1. mysql.db has column Event_priv at column 20 (0 based);
+    2. mysql.user has column Event_priv at column 29 (0 based);
+  SYNOPSIS
+    Events::check_system_tables()
+      thd  Thread
+  RETURN VALUE
+    FALSE  OK
+    TRUE   Error
+*/
+bool
+Events::check_system_tables(THD *thd)
+{
+  TABLE_LIST tables;
+  bool not_used;
+  Open_tables_state backup;
+  bool ret= FALSE;
+  DBUG_ENTER("Events::check_system_tables");
+  DBUG_PRINT("enter", ("thd=0x%lx", thd));
+  thd->reset_n_backup_open_tables_state(&backup);
+  bzero((char*) &tables, sizeof(tables));
+  tables.db= (char*) "mysql";
+  tables.table_name= tables.alias= (char*) "db";
+  tables.lock_type= TL_READ;
+  if ((ret= simple_open_n_lock_tables(thd, &tables)))
+  {
+    sql_print_error("SCHEDULER: Cannot open mysql.db");
+    ret= TRUE;
+  }
+  ret= table_check_intact(tables.table, MYSQL_DB_FIELD_COUNT,
+                          mysql_db_table_fields, &mysql_db_table_last_check,
+                          ER_CANNOT_LOAD_FROM_TABLE);
+  close_thread_tables(thd);
+  bzero((char*) &tables, sizeof(tables));
+  tables.db= (char*) "mysql";
+  tables.table_name= tables.alias= (char*) "user";
+  tables.lock_type= TL_READ;
+  if (simple_open_n_lock_tables(thd, &tables))
+  {
+    sql_print_error("SCHEDULER: Cannot open mysql.user");
+    ret= TRUE;
+  }
+  else
+  {
+    if (tables.table->s->fields < 29 ||
+        strncmp(tables.table->field[29]->field_name,
+                STRING_WITH_LEN("Event_priv")))
+    {
+      sql_print_error("mysql.user has no `Event_priv` column at position %d",
+                      29);
+      ret= TRUE;
+    }
+    close_thread_tables(thd);
+  }
+end:
+  thd->restore_backup_open_tables_state(&backup);
+  DBUG_RETURN(ret);
+}
--- a/sql/events.h
+++ b/sql/events.h
@@ -42,12 +42,12 @@ sortcmp_lex_string(LEX_STRING s, LEX_STRING t, CHARSET_INFO *cs);
 class Events
 {
 public:
-  friend class Event_queue_element;
  /*
    Quite NOT the best practice and will be removed once
    Event_timed::drop() and Event_timed is fixed not do drop directly
    or other scheme will be found.
  */
+  friend class Event_queue_element;
  static ulong opt_event_scheduler;
  static TYPELIB opt_typelib;
@@ -71,30 +71,30 @@ class Events
  stop_execution_of_events();
  bool
-  is_started();
+  is_execution_of_events_started();
-  static Events*
+  static Events *
  get_instance();
-  int
+  bool
  create_event(THD *thd, Event_parse_data *parse_data, bool if_exists,
               uint *rows_affected);
-  int
+  bool
  update_event(THD *thd, Event_parse_data *parse_data, sp_name *rename_to,
               uint *rows_affected);
-  int
+  bool
  drop_event(THD *thd, LEX_STRING dbname, LEX_STRING name, bool if_exists,
             uint *rows_affected, bool only_from_disk);
-  int
+  void
  drop_schema_events(THD *thd, char *db);
  int
  open_event_table(THD *thd, enum thr_lock_type lock_type, TABLE **table);
-  int
+  bool
  show_create_event(THD *thd, LEX_STRING dbname, LEX_STRING name);
  /* Needed for both SHOW CREATE EVENT and INFORMATION_SCHEMA */
@@ -109,8 +109,11 @@ class Events
  dump_internal_status(THD *thd);
 private:
+  bool
+  check_system_tables(THD *thd);
  /* Singleton DP is used */
-  Events(){}
+  Events();
  ~Events(){}
  /* Singleton instance */
@@ -122,6 +125,8 @@ class Events
  pthread_mutex_t LOCK_event_metadata;
+  bool check_system_tables_error;
  /* Prevent use of these */
  Events(const Events &);
  void operator=(Events &);

--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -3978,7 +3978,7 @@ byte *sys_var_event_scheduler::value_ptr(THD *thd, enum_var_type type,
 {
  if (Events::opt_event_scheduler == 0)
    thd->sys_var_tmp.long_value= 0;
-  else if (Events::get_instance()->is_started())
+  else if (Events::get_instance()->is_execution_of_events_started())
    thd->sys_var_tmp.long_value= 1;
  else
    thd->sys_var_tmp.long_value= 2;

--- a/sql/share/errmsg.txt
+++ b/sql/share/errmsg.txt
@@ -5851,3 +5851,5 @@ ER_CANT_DROP_LOG_TABLE
        eng "Cannot drop log table if log is enabled"
 ER_EVENT_RECURSIVITY_FORBIDDEN
        eng "Recursivity of EVENT DDL statements is forbidden when body is present"
+ER_EVENTS_DB_ERROR
+        eng "Cannot proceed because the tables used by events were found damaged at server start"
--- a/sql/sql_db.cc
+++ b/sql/sql_db.cc
@@ -949,7 +949,7 @@ bool mysql_rm_db(THD *thd,char *db,bool if_exists, bool silent)
 exit:
  (void)sp_drop_db_routines(thd, db); /* QQ Ignore errors for now  */
-  error= Events::get_instance()->drop_schema_events(thd, db);
+  Events::get_instance()->drop_schema_events(thd, db);
  /*
    If this database was the client's selected database, we silently
    change the client's selected database to nothing (to have an empty

--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -1445,11 +1445,11 @@ ev_sql_stmt:
          {
            LEX *lex=Lex;
-            // return back to the original memory root ASAP
+            /* return back to the original memory root ASAP */
            lex->sphead->init_strings(YYTHD, lex);
            lex->sphead->restore_thd_mem_root(YYTHD);
-            lex->sp_chistics.suid= SP_IS_SUID;//always the definer!
+            lex->sp_chistics.suid= SP_IS_SUID;  //always the definer!
            Lex->event_parse_data->init_body(YYTHD);
          }
@@ -1568,9 +1568,9 @@ create_function_tail:
 	    sp->m_type= TYPE_ENUM_FUNCTION;
 	    lex->sphead= sp;
 	    /*
-	     * We have to turn of CLIENT_MULTI_QUERIES while parsing a
+	      We have to turn off CLIENT_MULTI_QUERIES while parsing a
-	     * stored procedure, otherwise yylex will chop it into pieces
+	      stored procedure, otherwise yylex will chop it into pieces
-	     * at each ';'.
+	      at each ';'.
 	    */
            $<ulong_num>$= YYTHD->client_capabilities & CLIENT_MULTI_QUERIES;
 	    YYTHD->client_capabilities &= ~CLIENT_MULTI_QUERIES;
@@ -4684,14 +4684,13 @@ alter:
              If it had to be supported spname had to be added to
              Event_parse_data.
            */
-            Lex->spname= NULL;
            if (!(Lex->event_parse_data= Event_parse_data::new_instance(YYTHD)))
              YYABORT;
            Lex->event_parse_data->identifier= $3;
            /*
-              We have to turn of CLIENT_MULTI_QUERIES while parsing a
+              We have to turn off CLIENT_MULTI_QUERIES while parsing a
              stored procedure, otherwise yylex will chop it into pieces
              at each ';'.
            */
@@ -4757,9 +4756,11 @@ ev_alter_on_schedule_completion: /* empty */ { $$= 0;}
 opt_ev_rename_to: /* empty */ { $$= 0;}
        | RENAME TO_SYM sp_name
          {
-            LEX *lex=Lex;
+            /*
-            lex->spname= $3; //use lex's spname to hold the new name
+              Use lex's spname to hold the new name.
-	                     //the original name is in the Event_parse_data object
+              The original name is in the Event_parse_data object
+            */
+            Lex->spname= $3; 
            $$= 1;
          }
      ;
@@ -4783,7 +4784,7 @@ alter_commands:
        | remove_partitioning
        | partitioning
 /*
-  This part was added for release 5.1 by Mikael Ronström.
+  This part was added for release 5.1 by Mikael Ronstrm.
  From here we insert a number of commands to manage the partitions of a
  partitioned table such as adding partitions, dropping partitions,
  reorganising partitions in various manners. In future releases the list

--- a/sql/table.cc
+++ b/sql/table.cc
@@ -2352,28 +2352,28 @@ bool check_column_name(const char *name)
  Checks whether a table is intact. Should be done *just* after the table has
  been opened.
-  Synopsis
+  SYNOPSIS
    table_check_intact()
-      table         - the table to check
+      table             The table to check
-      table_f_count - expected number of columns in the table
+      table_f_count     Expected number of columns in the table
-      table_def     - expected structure of the table (column name and type)
+      table_def         Expected structure of the table (column name and type)
-    last_create_time- the table->file->create_time of the table in memory
+      last_create_time  The table->file->create_time of the table in memory
                        we have checked last time
-      error_num     - ER_XXXX from the error messages file. When 0 no error
+      error_num         ER_XXXX from the error messages file. When 0 no error
                        is sent to the client in case types does not match.
                        If different col number either 
                        ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE or 
                        ER_COL_COUNT_DOESNT_MATCH_CORRUPTED is used
  RETURNS
-    0   - OK
+    FALSE  OK
-    1   - There was an error
+    TRUE   There was an error
 */
 my_bool
-table_check_intact(TABLE *table, uint table_f_count,
+table_check_intact(TABLE *table, const uint table_f_count,
-                   TABLE_FIELD_W_TYPE *table_def, time_t *last_create_time,
+                   const TABLE_FIELD_W_TYPE *table_def,
-                   int error_num)
+                   time_t *last_create_time, int error_num)
 {
  uint i;
  my_bool error= FALSE;
@@ -2388,7 +2388,7 @@ table_check_intact(TABLE *table, uint table_f_count,
    DBUG_PRINT("info", ("I am suspecting, checking table"));
    if (fields_diff_count)
    {
-      // previous MySQL version
+      /* previous MySQL version */
      error= TRUE;
      if (MYSQL_VERSION_ID > table->s->mysql_version)
      {
@@ -2411,22 +2411,22 @@ table_check_intact(TABLE *table, uint table_f_count,
      else
      {
        /*
-          moving from newer mysql to older one -> let's say not an error but
+          Moving from newer mysql to older one -> let's say not an error but
          will check the definition afterwards. If a column was added at the
          end then we don't care much since it's not in the middle.
        */
        error= FALSE;
      }
    }
-    //definitely something has changed
+    /* definitely something has changed */
    char buffer[255];
    for (i=0 ; i < table_f_count; i++, table_def++)
    {      
      String sql_type(buffer, sizeof(buffer), system_charset_info);
      sql_type.length(0);
      /*
-        name changes are not fatal, we use sequence numbers => no prob for us
+        Name changes are not fatal, we use sequence numbers => no problem
-        but this can show tampered table or broken table.
+        for us but this can show tampered table or broken table.
      */
      if (i < table->s->fields)
      {
@@ -2440,7 +2440,7 @@ table_check_intact(TABLE *table, uint table_f_count,
        }
        /*
-          IF the type does not match than something is really wrong
+          If the type does not match than something is really wrong
          Check up to length - 1. Why?
          1. datetime -> datetim -> the same
          2. int(11) -> int(11  -> the same

--- a/sql/table.h
+++ b/sql/table.h
@@ -965,9 +965,9 @@ typedef struct st_table_field_w_type
 my_bool
-table_check_intact(TABLE *table, uint table_f_count,
+table_check_intact(TABLE *table, const uint table_f_count,
-                   TABLE_FIELD_W_TYPE *table_def, time_t *last_create_time,
+                   const TABLE_FIELD_W_TYPE * const table_def,
-                   int error_num);
+                   time_t *last_create_time, int error_num);
 static inline my_bitmap_map *tmp_use_all_columns(TABLE *table,
                                                 MY_BITMAP *bitmap)