summaryrefslogtreecommitdiff
path: root/sql/events.cc
blob: 196c8df591da4556874695c1c8f9098544b27250 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
/*
   Copyright (c) 2005, 2013, Oracle and/or its affiliates.
   Copyright (c) 2017, MariaDB Corporation.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include "mariadb.h"
#include "sql_priv.h"
#include "unireg.h"
#include "sql_parse.h"                          // check_access
#include "sql_base.h"                           // close_mysql_tables
#include "sql_show.h"                           // append_definer
#include "events.h"
#include "sql_db.h"                          // check_db_dir_existence
#include "sql_table.h"                       // write_bin_log
#include "tztime.h"                             // struct Time_zone
#include "sql_acl.h"                            // EVENT_ACL
#include "records.h"          // init_read_record, end_read_record
#include "event_data_objects.h"
#include "event_db_repository.h"
#include "event_queue.h"
#include "event_scheduler.h"
#include "sp_head.h" // for Stored_program_creation_ctx
#include "set_var.h"
#include "lock.h"   // lock_object_name

/**
  @addtogroup Event_Scheduler
  @{
*/

/*
 TODO list :
 - CREATE EVENT should not go into binary log! Does it now? The SQL statements
   issued by the EVENT are replicated.
   I have an idea how to solve the problem at failover. So the status field
   will be ENUM('DISABLED', 'ENABLED', 'SLAVESIDE_DISABLED').
   In this case when CREATE EVENT is replicated it should go into the binary
   as SLAVESIDE_DISABLED if it is ENABLED, when it's created as DISABLEd it
   should be replicated as disabled. If an event is ALTERed as DISABLED the
   query should go untouched into the binary log, when ALTERed as enable then
   it should go as SLAVESIDE_DISABLED. This is regarding the SQL interface.
   TT routines however modify mysql.event internally and this does not go the
   log so in this case queries has to be injected into the log...somehow... or
   maybe a solution is RBR for this case, because the event may go only from
   ENABLED to DISABLED status change and this is safe for replicating. As well
   an event may be deleted which is also safe for RBR.

 - Add logging to file

*/


/*
  If the user (un)intentionally removes an event directly from mysql.event
  the following sequence has to be used to be able to remove the in-memory
  counterpart.
  1. CREATE EVENT the_name ON SCHEDULE EVERY 1 SECOND DISABLE DO SELECT 1;
  2. DROP EVENT the_name

  In other words, the first one will create a row in mysql.event . In the
  second step because there will be a line, disk based drop will pass and
  the scheduler will remove the memory counterpart. The reason is that
  in-memory queue does not check whether the event we try to drop from memory
  is disabled. Disabled events are not kept in-memory because they are not
  eligible for execution.
*/

Event_queue *Events::event_queue;
Event_scheduler *Events::scheduler;
Event_db_repository *Events::db_repository;
ulong Events::opt_event_scheduler= Events::EVENTS_OFF;
ulong Events::startup_state= Events::EVENTS_OFF;
ulong Events::inited;


/*
  Compares 2 LEX strings regarding case.

  SYNOPSIS
    sortcmp_lex_string()
      s   First LEX_STRING
      t   Second LEX_STRING
      cs  Charset

  RETURN VALUE
   -1   s < t
    0   s == t
    1   s > t
*/

int sortcmp_lex_string(const LEX_CSTRING *s, const LEX_CSTRING *t,
                       const CHARSET_INFO *cs)
{
 return cs->coll->strnncollsp(cs, (uchar *) s->str, s->length,
                                  (uchar *) t->str, t->length);
}


/**
  Push an error into the error stack if the system tables are
  not up to date.
*/

bool Events::check_if_system_tables_error()
{
  DBUG_ENTER("Events::check_if_system_tables_error");

  if (!inited)
  {
    my_error(ER_EVENTS_DB_ERROR, MYF(0));
    DBUG_RETURN(TRUE);
  }

  DBUG_RETURN(FALSE);
}


/**
  Reconstructs interval expression from interval type and expression
  value that is in form of a value of the smalles entity:
  For
    YEAR_MONTH - expression is in months
    DAY_MINUTE - expression is in minutes

  SYNOPSIS
    Events::reconstruct_interval_expression()
      buf         Preallocated String buffer to add the value to
      interval    The interval type (for instance YEAR_MONTH)
      expression  The value in the lowest entity

  RETURN VALUE
    0  OK
    1  Error
*/

int
Events::reconstruct_interval_expression(String *buf, interval_type interval,
                                        longlong expression)
{
  ulonglong expr= expression;
  char tmp_buff[128], *end;
  bool close_quote= TRUE;
  int multipl= 0;
  char separator=':';

  switch (interval) {
  case INTERVAL_YEAR_MONTH:
    multipl= 12;
    separator= '-';
    goto common_1_lev_code;
  case INTERVAL_DAY_HOUR:
    multipl= 24;
    separator= ' ';
    goto common_1_lev_code;
  case INTERVAL_HOUR_MINUTE:
  case INTERVAL_MINUTE_SECOND:
    multipl= 60;
common_1_lev_code:
    buf->append('\'');
    end= longlong10_to_str(expression/multipl, tmp_buff, 10);
    buf->append(tmp_buff, (uint) (end- tmp_buff));
    expr= expr - (expr/multipl)*multipl;
    break;
  case INTERVAL_DAY_MINUTE:
  {
    ulonglong tmp_expr= expr;

    tmp_expr/=(24*60);
    buf->append('\'');
    end= longlong10_to_str(tmp_expr, tmp_buff, 10);
    buf->append(tmp_buff, (uint) (end- tmp_buff));// days
    buf->append(' ');

    tmp_expr= expr - tmp_expr*(24*60);//minutes left
    end= longlong10_to_str(tmp_expr/60, tmp_buff, 10);
    buf->append(tmp_buff, (uint) (end- tmp_buff));// hours

    expr= tmp_expr - (tmp_expr/60)*60;
    /* the code after the switch will finish */
    break;
  }
  case INTERVAL_HOUR_SECOND:
  {
    ulonglong tmp_expr= expr;

    buf->append('\'');
    end= longlong10_to_str(tmp_expr/3600, tmp_buff, 10);
    buf->append(tmp_buff, (uint) (end- tmp_buff));// hours
    buf->append(':');

    tmp_expr= tmp_expr - (tmp_expr/3600)*3600;
    end= longlong10_to_str(tmp_expr/60, tmp_buff, 10);
    buf->append(tmp_buff, (uint) (end- tmp_buff));// minutes

    expr= tmp_expr - (tmp_expr/60)*60;
    /* the code after the switch will finish */
    break;
  }
  case INTERVAL_DAY_SECOND:
  {
    ulonglong tmp_expr= expr;

    tmp_expr/=(24*3600);
    buf->append('\'');
    end= longlong10_to_str(tmp_expr, tmp_buff, 10);
    buf->append(tmp_buff, (uint) (end- tmp_buff));// days
    buf->append(' ');

    tmp_expr= expr - tmp_expr*(24*3600);//seconds left
    end= longlong10_to_str(tmp_expr/3600, tmp_buff, 10);
    buf->append(tmp_buff, (uint) (end- tmp_buff));// hours
    buf->append(':');

    tmp_expr= tmp_expr - (tmp_expr/3600)*3600;
    end= longlong10_to_str(tmp_expr/60, tmp_buff, 10);
    buf->append(tmp_buff, (uint) (end- tmp_buff));// minutes

    expr= tmp_expr - (tmp_expr/60)*60;
    /* the code after the switch will finish */
    break;
  }
  case INTERVAL_DAY_MICROSECOND:
  case INTERVAL_HOUR_MICROSECOND:
  case INTERVAL_MINUTE_MICROSECOND:
  case INTERVAL_SECOND_MICROSECOND:
  case INTERVAL_MICROSECOND:
    my_error(ER_NOT_SUPPORTED_YET, MYF(0), "MICROSECOND");
    return 1;
  case INTERVAL_QUARTER:
    expr/= 3;
    close_quote= FALSE;
    break;
  case INTERVAL_WEEK:
    expr/= 7;
    close_quote= FALSE;
    break;
  default:
    close_quote= FALSE;
    break;
  }
  if (close_quote)
    buf->append(separator);
  end= longlong10_to_str(expr, tmp_buff, 10);
  buf->append(tmp_buff, (uint) (end- tmp_buff));
  if (close_quote)
    buf->append('\'');

  return 0;
}


/**
  Create a new query string for removing executable comments
  for avoiding leak and keeping consistency of the execution
  on master and slave.

  @param[in] thd                 Thread handler
  @param[in] buf                 Query string

  @return
             0           ok
             1           error
*/
static int
create_query_string(THD *thd, String *buf)
{
  buf->length(0);
  /* Append the "CREATE" part of the query */
  if (thd->lex->create_info.or_replace())
  {
    if (buf->append(STRING_WITH_LEN("CREATE OR REPLACE ")))
      return 1;
  }
  else if (buf->append(STRING_WITH_LEN("CREATE ")))
    return 1;
  /* Append definer */
  append_definer(thd, buf, &(thd->lex->definer->user), &(thd->lex->definer->host));
  /* Append the left part of thd->query after "DEFINER" part */
  if (buf->append(thd->lex->stmt_definition_begin,
                  thd->lex->stmt_definition_end -
                  thd->lex->stmt_definition_begin))
    return 1;

  return 0;
}


/**
  Create a new event.

  @param[in,out]  thd            THD
  @param[in]      parse_data     Event's data from parsing stage

  In case there is an event with the same name (db) and
  IF NOT EXISTS is specified, an warning is put into the stack.
  @sa Events::drop_event for the notes about locking, pre-locking
  and Events DDL.

  @retval  FALSE  OK
  @retval  TRUE   Error (reported)
*/

bool
Events::create_event(THD *thd, Event_parse_data *parse_data)
{
  bool ret;
  bool event_already_exists;
  enum_binlog_format save_binlog_format;
  DBUG_ENTER("Events::create_event");

  if (unlikely(check_if_system_tables_error()))
    DBUG_RETURN(TRUE);

  /*
    Perform semantic checks outside of Event_db_repository:
    once CREATE EVENT is supported in prepared statements, the
    checks will be moved to PREPARE phase.
  */
  if (parse_data->check_parse_data(thd))
    DBUG_RETURN(TRUE);

  /* At create, one of them must be set */
  DBUG_ASSERT(parse_data->expression || parse_data->execute_at);

  if (check_access(thd, EVENT_ACL, parse_data->dbname.str, NULL, NULL, 0, 0))
    DBUG_RETURN(TRUE);
  WSREP_TO_ISOLATION_BEGIN(WSREP_MYSQL_DB, NULL, NULL);

  if (lock_object_name(thd, MDL_key::EVENT,
                       parse_data->dbname.str, parse_data->name.str))
    DBUG_RETURN(TRUE);

  if (check_db_dir_existence(parse_data->dbname.str))
  {
    my_error(ER_BAD_DB_ERROR, MYF(0), parse_data->dbname.str);
    DBUG_RETURN(TRUE);
  }

  if (parse_data->do_not_create)
    DBUG_RETURN(FALSE);
  /*
    Turn off row binlogging of this statement and use statement-based
    so that all supporting tables are updated for CREATE EVENT command.
  */
  save_binlog_format= thd->set_current_stmt_binlog_format_stmt();

  if (thd->lex->create_info.or_replace() && event_queue)
    event_queue->drop_event(thd, &parse_data->dbname, &parse_data->name);

  /* On error conditions my_error() is called so no need to handle here */
  if (!(ret= db_repository->create_event(thd, parse_data,
                                         &event_already_exists)))
  {
    Event_queue_element *new_element;
    bool dropped= 0;

    if (!event_already_exists)
    {
      if (!(new_element= new Event_queue_element()))
        ret= TRUE;                                // OOM
      else if ((ret= db_repository->load_named_event(thd, &parse_data->dbname,
                                                     &parse_data->name,
                                                     new_element)))
      {
        if (!db_repository->drop_event(thd, &parse_data->dbname,
                                       &parse_data->name, TRUE))
          dropped= 1;
        delete new_element;
      }
      else
      {
        /* TODO: do not ignore the out parameter and a possible OOM error! */
        bool created;
        if (event_queue)
          event_queue->create_event(thd, new_element, &created);
      }
    }
    /*
      binlog the create event unless it's been successfully dropped
    */
    if (!dropped)
    {
      /* Binlog the create event. */
      DBUG_ASSERT(thd->query() && thd->query_length());
      char buffer[1024];
      String log_query(buffer, sizeof(buffer), &my_charset_bin);
      if (create_query_string(thd, &log_query))
      {
        my_message_sql(ER_STARTUP,
                       "Event Error: An error occurred while creating query "
                       "string, before writing it into binary log.",
                       MYF(ME_ERROR_LOG));
        ret= true;
      }
      else
      {
        /*
          If the definer is not set or set to CURRENT_USER, the value
          of CURRENT_USER will be written into the binary log as the
          definer for the SQL thread.
        */
        ret= write_bin_log(thd, TRUE, log_query.ptr(), log_query.length());
      }
    }
  }

  thd->restore_stmt_binlog_format(save_binlog_format);

  DBUG_RETURN(ret);
#ifdef WITH_WSREP
wsrep_error_label:
  DBUG_RETURN(true);
#endif
}


/**
  Alter an event.

  @param[in,out] thd         THD
  @param[in]     parse_data  Event's data from parsing stage
  @param[in]     new_dbname  A new schema name for the event. Set in the case of
                             ALTER EVENT RENAME, otherwise is NULL.
  @param[in]     new_name    A new name for the event. Set in the case of
                             ALTER EVENT RENAME

  Parameter 'et' contains data about dbname and event name.
  Parameter 'new_name' is the new name of the event, if not null
  this means that RENAME TO was specified in the query
  @sa Events::drop_event for the locking notes.

  @retval  FALSE  OK
  @retval  TRUE   error (reported)
*/

bool
Events::update_event(THD *thd, Event_parse_data *parse_data,
                     LEX_CSTRING *new_dbname, LEX_CSTRING *new_name)
{
  int ret;
  enum_binlog_format save_binlog_format;
  Event_queue_element *new_element;

  DBUG_ENTER("Events::update_event");

  if (unlikely(check_if_system_tables_error()))
    DBUG_RETURN(TRUE);

  if (parse_data->check_parse_data(thd) || parse_data->do_not_create)
    DBUG_RETURN(TRUE);

  if (check_access(thd, EVENT_ACL, parse_data->dbname.str, NULL, NULL, 0, 0))
    DBUG_RETURN(TRUE);

  WSREP_TO_ISOLATION_BEGIN(WSREP_MYSQL_DB, NULL, NULL);

  if (lock_object_name(thd, MDL_key::EVENT,
                       parse_data->dbname.str, parse_data->name.str))
    DBUG_RETURN(TRUE);

  if (check_db_dir_existence(parse_data->dbname.str))
  {
    my_error(ER_BAD_DB_ERROR, MYF(0), parse_data->dbname.str);
    DBUG_RETURN(TRUE);
  }


  if (new_dbname)                               /* It's a rename */
  {
    /* Check that the new and the old names differ. */
    if ( !sortcmp_lex_string(&parse_data->dbname, new_dbname,
                             system_charset_info) &&
         !sortcmp_lex_string(&parse_data->name, new_name,
                             system_charset_info))
    {
      my_error(ER_EVENT_SAME_NAME, MYF(0));
      DBUG_RETURN(TRUE);
    }

    /*
      And the user has sufficient privileges to use the target database.
      Do it before checking whether the database exists: we don't want
      to tell the user that a database doesn't exist if they can not
      access it.
    */
    if (check_access(thd, EVENT_ACL, new_dbname->str, NULL, NULL, 0, 0))
      DBUG_RETURN(TRUE);

    /*
     Acquire mdl exclusive lock on target database name.
    */
    if (lock_object_name(thd, MDL_key::EVENT,
                         new_dbname->str, new_name->str))
      DBUG_RETURN(TRUE);

    /* Check that the target database exists */
    if (check_db_dir_existence(new_dbname->str))
    {
      my_error(ER_BAD_DB_ERROR, MYF(0), new_dbname->str);
      DBUG_RETURN(TRUE);
    }
  }

  /*
    Turn off row binlogging of this statement and use statement-based
    so that all supporting tables are updated for UPDATE EVENT command.
  */
  save_binlog_format= thd->set_current_stmt_binlog_format_stmt();

  /* On error conditions my_error() is called so no need to handle here */
  if (!(ret= db_repository->update_event(thd, parse_data,
                                         new_dbname, new_name)))
  {
    LEX_CSTRING dbname= new_dbname ? *new_dbname : parse_data->dbname;
    LEX_CSTRING name= new_name ? *new_name : parse_data->name;

    if (!(new_element= new Event_queue_element()))
      ret= TRUE;                                // OOM
    else if ((ret= db_repository->load_named_event(thd, &dbname, &name,
                                                   new_element)))
      delete new_element;
    else
    {
      /*
        TODO: check if an update actually has inserted an entry
        into the queue.
        If not, and the element is ON COMPLETION NOT PRESERVE, delete
        it right away.
      */
      if (event_queue)
        event_queue->update_event(thd, &parse_data->dbname, &parse_data->name,
                                  new_element);
      /* Binlog the alter event. */
      DBUG_ASSERT(thd->query() && thd->query_length());
      ret= write_bin_log(thd, TRUE, thd->query(), thd->query_length());
    }
  }

  thd->restore_stmt_binlog_format(save_binlog_format);
  DBUG_RETURN(ret);
#ifdef WITH_WSREP
wsrep_error_label:
  DBUG_RETURN(true);
#endif
}


/**
  Drops an event

  @param[in,out]  thd        THD
  @param[in]      dbname     Event's schema
  @param[in]      name       Event's name
  @param[in]      if_exists  When this is set and the event does not exist
                             a warning is pushed into the warning stack.
                             Otherwise the operation produces an error.

  @note Similarly to DROP PROCEDURE, we do not allow DROP EVENT
  under LOCK TABLES mode, unless table mysql.event is locked.  To
  ensure that, we do not reset & backup the open tables state in
  this function - if in LOCK TABLES or pre-locking mode, this will
  lead to an error 'Table mysql.event is not locked with LOCK
  TABLES' unless it _is_ locked. In pre-locked mode there is
  another barrier - DROP EVENT commits the current transaction,
  and COMMIT/ROLLBACK is not allowed in stored functions and
  triggers.

  @retval  FALSE  OK
  @retval  TRUE   Error (reported)
*/

bool
Events::drop_event(THD *thd, const LEX_CSTRING *dbname,
                   const LEX_CSTRING *name, bool if_exists)
{
  int ret;
  enum_binlog_format save_binlog_format;
  DBUG_ENTER("Events::drop_event");

  if (unlikely(check_if_system_tables_error()))
    DBUG_RETURN(TRUE);

  if (check_access(thd, EVENT_ACL, dbname->str, NULL, NULL, 0, 0))
    DBUG_RETURN(TRUE);

  WSREP_TO_ISOLATION_BEGIN(WSREP_MYSQL_DB, NULL, NULL);

  /*
    Turn off row binlogging of this statement and use statement-based so
    that all supporting tables are updated for DROP EVENT command.
  */
  save_binlog_format= thd->set_current_stmt_binlog_format_stmt();

  if (lock_object_name(thd, MDL_key::EVENT,
                       dbname->str, name->str))
    DBUG_RETURN(TRUE);
  /* On error conditions my_error() is called so no need to handle here */
  if (!(ret= db_repository->drop_event(thd, dbname, name, if_exists)))
  {
    if (event_queue)
      event_queue->drop_event(thd, dbname, name);
    /* Binlog the drop event. */
    DBUG_ASSERT(thd->query() && thd->query_length());
    ret= write_bin_log(thd, TRUE, thd->query(), thd->query_length());
  }

  thd->restore_stmt_binlog_format(save_binlog_format);
  DBUG_RETURN(ret);
#ifdef WITH_WSREP
wsrep_error_label:
  DBUG_RETURN(true);
#endif
}


/**
  Drops all events from a schema

  @note We allow to drop all events in a schema even if the
  scheduler is disabled. This is to not produce any warnings
  in case of DROP DATABASE and a disabled scheduler.

  @param[in,out]  thd  Thread
  @param[in]      db   ASCIIZ schema name
*/

void
Events::drop_schema_events(THD *thd, const char *db)
{
  const LEX_CSTRING db_lex= { db, strlen(db) };

  DBUG_ENTER("Events::drop_schema_events");
  DBUG_PRINT("enter", ("dropping events from %s", db));

  DBUG_SLOW_ASSERT(ok_for_lower_case_names(db));

  /*
    Sic: no check if the scheduler is disabled or system tables
    are damaged, as intended.
  */
  if (event_queue)
    event_queue->drop_schema_events(thd, &db_lex);
  db_repository->drop_schema_events(thd, &db_lex);

  DBUG_VOID_RETURN;
}


/**
  A helper function to generate SHOW CREATE EVENT output from
  a named event
*/

static bool
send_show_create_event(THD *thd, Event_timed *et, Protocol *protocol)
{
  char show_str_buf[10 * STRING_BUFFER_USUAL_SIZE];
  String show_str(show_str_buf, sizeof(show_str_buf), system_charset_info);
  List<Item> field_list;
  LEX_CSTRING sql_mode;
  const String *tz_name;
  MEM_ROOT *mem_root= thd->mem_root;
  DBUG_ENTER("send_show_create_event");

  show_str.length(0);
  if (et->get_create_event(thd, &show_str))
    DBUG_RETURN(TRUE);

  field_list.push_back(new (mem_root)
                       Item_empty_string(thd, "Event", NAME_CHAR_LEN),
                       mem_root);

  if (sql_mode_string_representation(thd, et->sql_mode, &sql_mode))
    DBUG_RETURN(TRUE);

  field_list.push_back(new (mem_root)
                       Item_empty_string(thd, "sql_mode",
                                         (uint) sql_mode.length), mem_root);

  tz_name= et->time_zone->get_name();

  field_list.push_back(new (mem_root)
                       Item_empty_string(thd, "time_zone", tz_name->length()),
                       mem_root);

  field_list.push_back(new (mem_root)
                       Item_empty_string(thd, "Create Event",
                                         show_str.length()), mem_root);

  field_list.push_back(new (mem_root)
                       Item_empty_string(thd, "character_set_client",
                                         MY_CS_NAME_SIZE), mem_root);

  field_list.push_back(new (mem_root)
                       Item_empty_string(thd, "collation_connection",
                                         MY_CS_NAME_SIZE), mem_root);

  field_list.push_back(new (mem_root)
                       Item_empty_string(thd, "Database Collation",
                                         MY_CS_NAME_SIZE), mem_root);

  if (protocol->send_result_set_metadata(&field_list,
                            Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF))
    DBUG_RETURN(TRUE);

  protocol->prepare_for_resend();

  protocol->store(et->name.str, et->name.length, system_charset_info);
  protocol->store(sql_mode.str, sql_mode.length, system_charset_info);
  protocol->store(tz_name->ptr(), tz_name->length(), system_charset_info);
  protocol->store(show_str.ptr(), show_str.length(),
                  et->creation_ctx->get_client_cs());
  protocol->store(et->creation_ctx->get_client_cs()->csname,
                  strlen(et->creation_ctx->get_client_cs()->csname),
                  system_charset_info);
  protocol->store(et->creation_ctx->get_connection_cl()->name,
                  strlen(et->creation_ctx->get_connection_cl()->name),
                  system_charset_info);
  protocol->store(et->creation_ctx->get_db_cl()->name,
                  strlen(et->creation_ctx->get_db_cl()->name),
                  system_charset_info);

  if (protocol->write())
    DBUG_RETURN(TRUE);

  my_eof(thd);

  DBUG_RETURN(FALSE);
}


/**
  Implement SHOW CREATE EVENT statement

      thd   Thread context
      spn   The name of the event (db, name)

  @retval  FALSE  OK
  @retval  TRUE   error (reported)
*/

bool
Events::show_create_event(THD *thd, const LEX_CSTRING *dbname,
                          const LEX_CSTRING *name)
{
  Event_timed et;
  bool ret;

  DBUG_ENTER("Events::show_create_event");
  DBUG_PRINT("enter", ("name: %s@%s", dbname->str, name->str));

  if (unlikely(check_if_system_tables_error()))
    DBUG_RETURN(TRUE);

  if (check_access(thd, EVENT_ACL, dbname->str, NULL, NULL, 0, 0))
    DBUG_RETURN(TRUE);

  /*
    We would like to allow SHOW CREATE EVENT under LOCK TABLES and
    in pre-locked mode. mysql.event table is marked as a system table.
    This flag reduces the set of its participation scenarios in LOCK TABLES
    operation, and therefore an out-of-bound open of this table
    for reading like the one below (sic, only for reading) is
    more or less deadlock-free. For additional information about when a
    deadlock can occur please refer to the description of 'system table'
    flag.
  */
  ret= db_repository->load_named_event(thd, dbname, name, &et);

  if (!ret)
    ret= send_show_create_event(thd, &et, thd->protocol);

  DBUG_RETURN(ret);
}


/**
  Check access rights and fill INFORMATION_SCHEMA.events table.

  @param[in,out]  thd     Thread context
  @param[in]      tables  The temporary table to fill.

  In MySQL INFORMATION_SCHEMA tables are temporary tables that are
  created and filled on demand. In this function, we fill
  INFORMATION_SCHEMA.events. It is a callback for I_S module, invoked from
  sql_show.cc

  @return Has to be integer, as such is the requirement of the I_S API
  @retval  0  success
  @retval  1  an error, pushed into the error stack
*/

int
Events::fill_schema_events(THD *thd, TABLE_LIST *tables, COND * /* cond */)
{
  const char *db= NULL;
  int ret;
  char db_tmp[SAFE_NAME_LEN];
  DBUG_ENTER("Events::fill_schema_events");

  /*
    If we didn't start events because of --skip-grant-tables, return an
    empty set
  */
  if (opt_noacl)
    DBUG_RETURN(0);

  if (unlikely(check_if_system_tables_error()))
    DBUG_RETURN(1);

  /*
    If it's SHOW EVENTS then thd->lex->select_lex.db is guaranteed not to
    be NULL. Let's do an assert anyway.
  */
  if (thd->lex->sql_command == SQLCOM_SHOW_EVENTS)
  {
    DBUG_ASSERT(thd->lex->first_select_lex()->db.str);
    if (!is_infoschema_db(&thd->lex->first_select_lex()->db) && // There is no events in I_S
        check_access(thd, EVENT_ACL, thd->lex->first_select_lex()->db.str,
                     NULL, NULL, 0, 0))
      DBUG_RETURN(1);
    db= normalize_db_name(thd->lex->first_select_lex()->db.str,
                          db_tmp, sizeof(db_tmp));
  }
  ret= db_repository->fill_schema_events(thd, tables, db);

  DBUG_RETURN(ret);
}


/**
  Initializes the scheduler's structures.

  @param  THD or null (if called by init)
  @param  opt_noacl_or_bootstrap
                     TRUE if there is --skip-grant-tables or --bootstrap
                     option. In that case we disable the event scheduler.

  @note   This function is not synchronized.

  @retval  FALSE   Perhaps there was an error, and the event scheduler
                   is disabled. But the error is not fatal and the
                   server start up can continue.
  @retval  TRUE    Fatal error. Startup must terminate (call unireg_abort()).
*/

bool
Events::init(THD *thd, bool opt_noacl_or_bootstrap)
{
  int err_no;
  bool res= FALSE;
  bool had_thd= thd != 0;
  DBUG_ENTER("Events::init");

  DBUG_ASSERT(inited == 0);

  /*
    Was disabled explicitly from the command line
  */
  if (opt_event_scheduler == Events::EVENTS_DISABLED ||
      opt_noacl_or_bootstrap)
    DBUG_RETURN(FALSE);

  /* We need a temporary THD during boot */
  if (!thd)
  {

    if (!(thd= new THD(0)))
    {
      res= 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();
    /*
      Set current time for the thread that handles events.
      Current time is stored in data member start_time of THD class.
      Subsequently, this value is used to check whether event was expired
      when make loading events from storage. Check for event expiration time
      is done at Event_queue_element::compute_next_execution_time() where
      event's status set to Event_parse_data::DISABLED and dropped flag set
      to true if event was expired.
    */
    thd->set_time();
  }

  /*
    We will need Event_db_repository anyway, even if the scheduler is
    disabled - to perform events DDL.
  */
  if (!(db_repository= new Event_db_repository))
  {
    res= TRUE; /* fatal error: request unireg_abort */
    goto end;
  }

  /*
    Since we allow event DDL even if the scheduler is disabled,
    check the system tables, as we might need them.

    If run with --skip-grant-tables or --bootstrap, don't try to do the
    check of system tables and don't complain: in these modes the tables
    are most likely not there and we're going to disable the event
    scheduler anyway.
  */
  if (Event_db_repository::check_system_tables(thd))
  {
    delete db_repository;
    db_repository= 0;
    my_message(ER_STARTUP,
               "Event Scheduler: An error occurred when initializing "
               "system tables. Disabling the Event Scheduler.",
               MYF(ME_ERROR_LOG));
    /* Disable the scheduler since the system tables are not up to date */
    opt_event_scheduler= EVENTS_OFF;
    goto end;
  }


  DBUG_ASSERT(opt_event_scheduler == Events::EVENTS_ON ||
              opt_event_scheduler == Events::EVENTS_OFF);

  if (!(event_queue= new Event_queue) ||
      !(scheduler= new Event_scheduler(event_queue)))
  {
    res= TRUE; /* fatal error: request unireg_abort */
    goto end;
  }

  if (event_queue->init_queue(thd) || load_events_from_db(thd) ||
      (opt_event_scheduler == EVENTS_ON && scheduler->start(&err_no)))
  {
    my_message_sql(ER_STARTUP,
                   "Event Scheduler: Error while loading from mysql.event table.",
                   MYF(ME_ERROR_LOG));
    res= TRUE; /* fatal error: request unireg_abort */
    goto end;
  }
  Event_worker_thread::init(db_repository);
  inited= 1;

end:
  if (res)
    deinit();
  if (!had_thd)
    delete thd;

  DBUG_RETURN(res);
}

/*
  Cleans up scheduler's resources. Called at server shutdown.

  SYNOPSIS
    Events::deinit()

  NOTES
    This function is not synchronized.
*/

void
Events::deinit()
{
  DBUG_ENTER("Events::deinit");

  delete scheduler;
  scheduler= NULL;                            /* For restart */
  delete event_queue;
  event_queue= NULL;                          /* For restart */
  delete db_repository;
  db_repository= NULL;                        /* For restart */

  inited= 0;
  DBUG_VOID_RETURN;
}

#ifdef HAVE_PSI_INTERFACE
PSI_mutex_key key_LOCK_event_queue,
              key_event_scheduler_LOCK_scheduler_state;

static PSI_mutex_info all_events_mutexes[]=
{
  { &key_LOCK_event_queue, "LOCK_event_queue", PSI_FLAG_GLOBAL},
  { &key_event_scheduler_LOCK_scheduler_state, "Event_scheduler::LOCK_scheduler_state", PSI_FLAG_GLOBAL}
};

PSI_cond_key key_event_scheduler_COND_state, key_COND_queue_state;

static PSI_cond_info all_events_conds[]=
{
  { &key_event_scheduler_COND_state, "Event_scheduler::COND_state", PSI_FLAG_GLOBAL},
  { &key_COND_queue_state, "COND_queue_state", PSI_FLAG_GLOBAL},
};

PSI_thread_key key_thread_event_scheduler, key_thread_event_worker;

static PSI_thread_info all_events_threads[]=
{
  { &key_thread_event_scheduler, "event_scheduler", PSI_FLAG_GLOBAL},
  { &key_thread_event_worker, "event_worker", 0}
};
#endif /* HAVE_PSI_INTERFACE */

PSI_stage_info stage_waiting_on_empty_queue= { 0, "Waiting on empty queue", 0};
PSI_stage_info stage_waiting_for_next_activation= { 0, "Waiting for next activation", 0};
PSI_stage_info stage_waiting_for_scheduler_to_stop= { 0, "Waiting for the scheduler to stop", 0};

#ifdef HAVE_PSI_INTERFACE
PSI_stage_info *all_events_stages[]=
{
  & stage_waiting_on_empty_queue,
  & stage_waiting_for_next_activation,
  & stage_waiting_for_scheduler_to_stop
};

static void init_events_psi_keys(void)
{
  const char* category= "sql";
  int count;

  count= array_elements(all_events_mutexes);
  mysql_mutex_register(category, all_events_mutexes, count);

  count= array_elements(all_events_conds);
  mysql_cond_register(category, all_events_conds, count);

  count= array_elements(all_events_threads);
  mysql_thread_register(category, all_events_threads, count);

  count= array_elements(all_events_stages);
  mysql_stage_register(category, all_events_stages, count);

}
#endif /* HAVE_PSI_INTERFACE */

/**
  Inits Events mutexes

  SYNOPSIS
    Events::init_mutexes()
      thd  Thread
*/

void
Events::init_mutexes()
{
#ifdef HAVE_PSI_INTERFACE
  init_events_psi_keys();
#endif
}


/*
  Dumps the internal status of the scheduler and the memory cache
  into a table with two columns - Name & Value. Different properties
  which could be useful for debugging for instance deadlocks are
  returned.

  SYNOPSIS
    Events::dump_internal_status()
*/

void
Events::dump_internal_status()
{
  DBUG_ENTER("Events::dump_internal_status");
  puts("\n\n\nEvents status:");
  puts("LLA = Last Locked At  LUA = Last Unlocked At");
  puts("WOC = Waiting On Condition  DL = Data Locked");

  /*
    opt_event_scheduler should only be accessed while
    holding LOCK_global_system_variables.
  */
  mysql_mutex_lock(&LOCK_global_system_variables);
  if (!inited)
    puts("The Event Scheduler is disabled");
  else
  {
    scheduler->dump_internal_status();
    event_queue->dump_internal_status();
  }

  mysql_mutex_unlock(&LOCK_global_system_variables);
  DBUG_VOID_RETURN;
}

bool Events::start(int *err_no)
{
  DBUG_ASSERT(inited);
  return scheduler->start(err_no);
}

bool Events::stop()
{
  DBUG_ASSERT(inited);
  return scheduler->stop();
}

/**
  Loads all ENABLED events from mysql.event into a prioritized
  queue.

  This function is called during the server start up. It reads
  every event, computes the next execution time, and if the event
  needs execution, adds it to a prioritized queue. Otherwise, if
  ON COMPLETION DROP is specified, the event is automatically
  removed from the table.

  @param[in,out] thd Thread context. Used for memory allocation in some cases.

  @retval  FALSE  success
  @retval  TRUE   error, the load is aborted

  @note Reports the error to the console
*/

bool
Events::load_events_from_db(THD *thd)
{
  TABLE *table;
  READ_RECORD read_record_info;
  bool ret= TRUE;
  uint count= 0;
  ulong saved_master_access;
  DBUG_ENTER("Events::load_events_from_db");
  DBUG_PRINT("enter", ("thd: %p", thd));

  /*
    NOTE: even if we run in read-only mode, we should be able to lock the
    mysql.event table for writing. In order to achieve this, we should call
    mysql_lock_tables() under the super user.

    Same goes for transaction access mode.
    Temporarily reset it to read-write.
  */

  saved_master_access= thd->security_ctx->master_access;
  thd->security_ctx->master_access |= SUPER_ACL;
  bool save_tx_read_only= thd->tx_read_only;
  thd->tx_read_only= false;

  ret= db_repository->open_event_table(thd, TL_WRITE, &table);

  thd->tx_read_only= save_tx_read_only;
  thd->security_ctx->master_access= saved_master_access;

  if (ret)
  {
    my_message_sql(ER_STARTUP,
                   "Event Scheduler: Failed to open table mysql.event",
                   MYF(ME_ERROR_LOG));
    DBUG_RETURN(TRUE);
  }

  if (init_read_record(&read_record_info, thd, table, NULL, NULL, 0, 1, FALSE))
  {
    close_thread_tables(thd);
    DBUG_RETURN(TRUE);
  }

  while (!(read_record_info.read_record()))
  {
    Event_queue_element *et;
    bool created, dropped;

    if (!(et= new Event_queue_element))
      goto end;

    DBUG_PRINT("info", ("Loading event from row."));

    if (et->load_from_row(thd, table))
    {
      my_message(ER_STARTUP,
                 "Event Scheduler: "
                 "Error while loading events from mysql.event. "
                 "The table probably contains bad data or is corrupted",
                 MYF(ME_ERROR_LOG));
      delete et;
      goto end;
    }
    /**
      Since the Event_queue_element object could be deleted inside
      Event_queue::create_event we should save the value of dropped flag
      into the temporary variable.
    */
    dropped= et->dropped;
    if (event_queue->create_event(thd, et, &created))
    {
      /* Out of memory */
      delete et;
      goto end;
    }
    if (created)
      count++;
    else if (dropped)
    {
      /*
        If not created, a stale event - drop if immediately if
        ON COMPLETION NOT PRESERVE.
        XXX: This won't be replicated, thus the drop won't appear in
             in the slave. When the slave is restarted it will drop events.
             However, as the slave will be "out of sync", it might happen that
             an event created on the master, after master restart, won't be
             replicated to the slave correctly, as the create will fail there.
      */
      int rc= table->file->ha_delete_row(table->record[0]);
      if (rc)
      {
        table->file->print_error(rc, MYF(0));
        goto end;
      }
    }
  }
  my_printf_error(ER_STARTUP,
                  "Event Scheduler: Loaded %d event%s",
                  MYF(ME_ERROR_LOG |
                      (global_system_variables.log_warnings) ?
                      ME_NOTE: 0),
                  count, (count == 1) ? "" : "s");
  ret= FALSE;

end:
  end_read_record(&read_record_info);

  close_mysql_tables(thd);
  DBUG_RETURN(ret);
}

#ifdef WITH_WSREP
int wsrep_create_event_query(THD *thd, uchar** buf, size_t* buf_len)
{
  char buffer[1024];
  String log_query(buffer, sizeof(buffer), &my_charset_bin);

  if (create_query_string(thd, &log_query))
  {
    WSREP_WARN("events create string failed: schema: %s, query: %s",
               thd->get_db(), thd->query());
    return 1;
  }
  return wsrep_to_buf_helper(thd, log_query.ptr(), log_query.length(), buf, buf_len);
}
#endif /* WITH_WSREP */
/**
  @} (End of group Event_Scheduler)
*/