summaryrefslogtreecommitdiffstats
path: root/sql/transaction.cc
blob: a6dbf57c24afacb4bb88394421e1135d0fe579ab (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
/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
   Copyright (c) 2009, 2021, 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 Street, Fifth Floor, Boston, MA  02110-1335  USA */


#ifdef USE_PRAGMA_IMPLEMENTATION
#pragma implementation                         // gcc: Class implementation
#endif

#include "mariadb.h"
#include "sql_priv.h"
#include "transaction.h"
#include "debug_sync.h"         // DEBUG_SYNC
#include "sql_acl.h"
#include "semisync_master.h"
#include <pfs_transaction_provider.h>
#include <mysql/psi/mysql_transaction.h>
#ifdef WITH_WSREP
#include "wsrep_trans_observer.h"
#endif /* WITH_WSREP */

/**
  Helper: Tell tracker (if any) that transaction ended.
*/
void trans_track_end_trx(THD *thd)
{
#ifndef EMBEDDED_LIBRARY
  if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
    thd->session_tracker.transaction_info.end_trx(thd);
#endif //EMBEDDED_LIBRARY
}


/**
  Helper: transaction ended, SET TRANSACTION one-shot variables
  revert to session values. Let the transaction state tracker know.
*/
void trans_reset_one_shot_chistics(THD *thd)
{
#ifndef EMBEDDED_LIBRARY
  if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
  {
    thd->session_tracker.transaction_info.set_read_flags(thd, TX_READ_INHERIT);
    thd->session_tracker.transaction_info.set_isol_level(thd, TX_ISOL_INHERIT);
  }
#endif //EMBEDDED_LIBRARY
  thd->tx_isolation= (enum_tx_isolation) thd->variables.tx_isolation;
  thd->tx_read_only= thd->variables.tx_read_only;
}


/*
  Conditions under which the transaction state must not change

  @result TRUE  Transaction can not commit
  @result FALSE Transaction can commit
*/

static bool trans_check(THD *thd)
{
  DBUG_ENTER("trans_check");

  /*
    Always commit statement transaction before manipulating with
    the normal one.
  */
  DBUG_ASSERT(thd->transaction->stmt.is_empty());

  if (unlikely(thd->in_sub_stmt))
  {
    my_error(ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG, MYF(0));
    DBUG_RETURN(TRUE);
  }
  if (likely(!thd->transaction->xid_state.is_explicit_XA()))
    DBUG_RETURN(FALSE);

  thd->transaction->xid_state.er_xaer_rmfail();
  DBUG_RETURN(TRUE);
}


/**
  Begin a new transaction.

  @note Beginning a transaction implicitly commits any current
        transaction and releases existing locks.

  @param thd     Current thread
  @param flags   Transaction flags

  @retval FALSE  Success
  @retval TRUE   Failure
*/

bool trans_begin(THD *thd, uint flags)
{
  int res= FALSE;
  DBUG_ENTER("trans_begin");

  if (trans_check(thd))
    DBUG_RETURN(TRUE);

  if (thd->locked_tables_list.unlock_locked_tables(thd))
    DBUG_RETURN(true);

  DBUG_ASSERT(!thd->locked_tables_mode);

  if (thd->in_multi_stmt_transaction_mode() ||
      (thd->variables.option_bits & OPTION_TABLE_LOCK))
  {
    thd->variables.option_bits&= ~OPTION_TABLE_LOCK;
    thd->server_status&=
      ~(SERVER_STATUS_IN_TRANS | SERVER_STATUS_IN_TRANS_READONLY);
    DBUG_PRINT("info", ("clearing SERVER_STATUS_IN_TRANS"));
    res= MY_TEST(ha_commit_trans(thd, TRUE));
#ifdef WITH_WSREP
    if (wsrep_thd_is_local(thd))
    {
      res= res || wsrep_after_statement(thd);
    }
#endif /* WITH_WSREP */
  }

  thd->variables.option_bits&= ~(OPTION_BEGIN | OPTION_BINLOG_THIS_TRX);

  /*
    The following set should not be needed as transaction state should
    already be reset. We should at some point change this to an assert.
  */
  thd->transaction->all.reset();
  thd->has_waiter= false;
  thd->waiting_on_group_commit= false;
  thd->transaction->start_time.reset(thd);

  if (res)
    DBUG_RETURN(TRUE);

  /*
    Release transactional metadata locks only after the
    transaction has been committed.
  */
  thd->release_transactional_locks();

  // The RO/RW options are mutually exclusive.
  DBUG_ASSERT(!((flags & MYSQL_START_TRANS_OPT_READ_ONLY) &&
                (flags & MYSQL_START_TRANS_OPT_READ_WRITE)));
  if (flags & MYSQL_START_TRANS_OPT_READ_ONLY)
  {
    thd->tx_read_only= true;
#ifndef EMBEDDED_LIBRARY
    if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
      thd->session_tracker.transaction_info.set_read_flags(thd, TX_READ_ONLY);
#endif //EMBEDDED_LIBRARY
  }
  else if (flags & MYSQL_START_TRANS_OPT_READ_WRITE)
  {
    /*
      Explicitly starting a RW transaction when the server is in
      read-only mode, is not allowed unless the user has SUPER priv.
      Implicitly starting a RW transaction is allowed for backward
      compatibility.
    */
    const bool user_is_super=
      MY_TEST(thd->security_ctx->master_access & PRIV_IGNORE_READ_ONLY);
    if (opt_readonly && !user_is_super)
    {
      my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0), "--read-only");
      DBUG_RETURN(true);
    }
    thd->tx_read_only= false;
    /*
      This flags that tx_read_only was set explicitly, rather than
      just from the session's default.
    */
#ifndef EMBEDDED_LIBRARY
    if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
      thd->session_tracker.transaction_info.set_read_flags(thd, TX_READ_WRITE);
#endif //EMBEDDED_LIBRARY
  }

#ifdef WITH_WSREP
  if (wsrep_thd_is_local(thd))
  {
    if (wsrep_sync_wait(thd))
      DBUG_RETURN(TRUE);
    if (!thd->tx_read_only &&
        wsrep_start_transaction(thd, thd->wsrep_next_trx_id()))
      DBUG_RETURN(TRUE);
  }
#endif /* WITH_WSREP */

  thd->variables.option_bits|= OPTION_BEGIN;
  thd->server_status|= SERVER_STATUS_IN_TRANS;
  if (thd->tx_read_only)
    thd->server_status|= SERVER_STATUS_IN_TRANS_READONLY;
  DBUG_PRINT("info", ("setting SERVER_STATUS_IN_TRANS"));

#ifndef EMBEDDED_LIBRARY
  if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
    thd->session_tracker.transaction_info.add_trx_state(thd, TX_EXPLICIT);
#endif //EMBEDDED_LIBRARY

  /* ha_start_consistent_snapshot() relies on OPTION_BEGIN flag set. */
  if (flags & MYSQL_START_TRANS_OPT_WITH_CONS_SNAPSHOT)
  {
#ifndef EMBEDDED_LIBRARY
    if (thd->variables.session_track_transaction_info > TX_TRACK_NONE)
      thd->session_tracker.transaction_info.add_trx_state(thd, TX_WITH_SNAPSHOT);
#endif //EMBEDDED_LIBRARY
    res= ha_start_consistent_snapshot(thd);
  }
  /*
    Register transaction start in performance schema if not done already.
    We handle explicitly started transactions here, implicitly started
    transactions (and single-statement transactions in autocommit=1 mode)
    are handled in trans_register_ha().
    We can't handle explicit transactions in the same way as implicit
    because we want to correctly attribute statements which follow
    BEGIN but do not touch any transactional tables.
  */
  if (thd->m_transaction_psi == NULL)
  {
    thd->m_transaction_psi= MYSQL_START_TRANSACTION(&thd->m_transaction_state,
                                                 NULL, 0, thd->tx_isolation,
                                                 thd->tx_read_only, false);
    DEBUG_SYNC(thd, "after_set_transaction_psi_before_set_transaction_gtid");
    //gtid_set_performance_schema_values(thd);
  }

  DBUG_RETURN(MY_TEST(res));
}


/**
  Commit the current transaction, making its changes permanent.

  @param thd     Current thread

  @retval FALSE  Success
  @retval TRUE   Failure
*/

bool trans_commit(THD *thd)
{
  int res;
  DBUG_ENTER("trans_commit");

  if (trans_check(thd))
    DBUG_RETURN(TRUE);

  thd->server_status&=
    ~(SERVER_STATUS_IN_TRANS | SERVER_STATUS_IN_TRANS_READONLY);
  DBUG_PRINT("info", ("clearing SERVER_STATUS_IN_TRANS"));
  res= ha_commit_trans(thd, TRUE);

  mysql_mutex_assert_not_owner(&LOCK_prepare_ordered);
  mysql_mutex_assert_not_owner(mysql_bin_log.get_log_lock());
  mysql_mutex_assert_not_owner(&LOCK_after_binlog_sync);
  mysql_mutex_assert_not_owner(&LOCK_commit_ordered);

  /*
    if res is non-zero, then ha_commit_trans has rolled back the
    transaction, so the hooks for rollback will be called.
  */
#ifdef HAVE_REPLICATION
  if (res)
    repl_semisync_master.wait_after_rollback(thd, FALSE);
  else
    repl_semisync_master.wait_after_commit(thd, FALSE);
#endif
  thd->variables.option_bits&= ~(OPTION_BEGIN | OPTION_BINLOG_THIS_TRX);
  thd->transaction->all.reset();
  thd->lex->start_transaction_opt= 0;

  /* The transaction should be marked as complete in P_S. */
  DBUG_ASSERT(thd->m_transaction_psi == NULL);
  trans_track_end_trx(thd);

  DBUG_RETURN(MY_TEST(res));
}


/**
  Implicitly commit the current transaction.

  @note A implicit commit does not releases existing table locks.

  @param thd     Current thread

  @retval FALSE  Success
  @retval TRUE   Failure
*/

bool trans_commit_implicit(THD *thd)
{
  bool res= FALSE;
  DBUG_ENTER("trans_commit_implicit");

  if (trans_check(thd))
    DBUG_RETURN(TRUE);

  if (thd->variables.option_bits & OPTION_GTID_BEGIN)
  {
    DBUG_PRINT("error", ("OPTION_GTID_BEGIN is set. "
                         "Master and slave will have different GTID values"));
  }

  if (thd->in_multi_stmt_transaction_mode() ||
      (thd->variables.option_bits & OPTION_TABLE_LOCK))
  {
    /* Safety if one did "drop table" on locked tables */
    if (!thd->locked_tables_mode)
      thd->variables.option_bits&= ~OPTION_TABLE_LOCK;
    thd->server_status&=
      ~(SERVER_STATUS_IN_TRANS | SERVER_STATUS_IN_TRANS_READONLY);
    DBUG_PRINT("info", ("clearing SERVER_STATUS_IN_TRANS"));
    res= MY_TEST(ha_commit_trans(thd, TRUE));
  }

  thd->variables.option_bits&= ~(OPTION_BEGIN | OPTION_BINLOG_THIS_TRX);
  thd->transaction->all.reset();

  /* The transaction should be marked as complete in P_S. */
  DBUG_ASSERT(thd->m_transaction_psi == NULL);

  /*
    Upon implicit commit, reset the current transaction
    isolation level and access mode. We do not care about
    @@session.completion_type since it's documented
    to not have any effect on implicit commit.
  */
  trans_reset_one_shot_chistics(thd);

  trans_track_end_trx(thd);

  DBUG_RETURN(res);
}


/**
  Rollback the current transaction, canceling its changes.

  @param thd     Current thread

  @retval FALSE  Success
  @retval TRUE   Failure
*/

bool trans_rollback(THD *thd)
{
  int res;
  DBUG_ENTER("trans_rollback");

  if (trans_check(thd))
    DBUG_RETURN(TRUE);

  thd->server_status&=
    ~(SERVER_STATUS_IN_TRANS | SERVER_STATUS_IN_TRANS_READONLY);
  DBUG_PRINT("info", ("clearing SERVER_STATUS_IN_TRANS"));
  res= ha_rollback_trans(thd, TRUE);
#ifdef HAVE_REPLICATION
  repl_semisync_master.wait_after_rollback(thd, FALSE);
#endif
  /* Reset the binlog transaction marker */
  thd->variables.option_bits&= ~(OPTION_BEGIN | OPTION_BINLOG_THIS_TRX |
                                 OPTION_GTID_BEGIN);
  thd->transaction->all.reset();
  thd->lex->start_transaction_opt= 0;

  /* The transaction should be marked as complete in P_S. */
  DBUG_ASSERT(thd->m_transaction_psi == NULL);

  trans_track_end_trx(thd);

  DBUG_RETURN(MY_TEST(res));
}


/**
  Implicitly rollback the current transaction, typically
  after deadlock was discovered.

  @param thd     Current thread

  @retval False Success
  @retval True  Failure

  @note ha_rollback_low() which is indirectly called by this
        function will mark XA transaction for rollback by
        setting appropriate RM error status if there was
        transaction rollback request.
*/

bool trans_rollback_implicit(THD *thd)
{
  int res;
  DBUG_ENTER("trans_rollback_implict");

  /*
    Always commit/rollback statement transaction before manipulating
    with the normal one.
    Don't perform rollback in the middle of sub-statement, wait till
    its end.
  */
  DBUG_ASSERT(thd->transaction->stmt.is_empty() && !thd->in_sub_stmt);

  thd->server_status&= ~(SERVER_STATUS_IN_TRANS | SERVER_STATUS_IN_TRANS_READONLY);
  DBUG_PRINT("info", ("clearing SERVER_STATUS_IN_TRANS"));
  res= ha_rollback_trans(thd, true);
  /*
    We don't reset OPTION_BEGIN flag below to simulate implicit start
    of new transacton in @@autocommit=1 mode. This is necessary to
    preserve backward compatibility.
  */
  thd->variables.option_bits&= ~(OPTION_BINLOG_THIS_TRX);
  thd->transaction->all.reset();

  /* Rollback should clear transaction_rollback_request flag. */
  DBUG_ASSERT(!thd->transaction_rollback_request);
  /* The transaction should be marked as complete in P_S. */
  DBUG_ASSERT(thd->m_transaction_psi == NULL);

  trans_track_end_trx(thd);

  DBUG_RETURN(MY_TEST(res));
}


/**
  Commit the single statement transaction.

  @note Note that if the autocommit is on, then the following call
        inside InnoDB will commit or rollback the whole transaction
        (= the statement). The autocommit mechanism built into InnoDB
        is based on counting locks, but if the user has used LOCK
        TABLES then that mechanism does not know to do the commit.

  @param thd     Current thread

  @retval FALSE  Success
  @retval TRUE   Failure
*/

bool trans_commit_stmt(THD *thd)
{
  DBUG_ENTER("trans_commit_stmt");
  int res= FALSE;
  /*
    We currently don't invoke commit/rollback at end of
    a sub-statement.  In future, we perhaps should take
    a savepoint for each nested statement, and release the
    savepoint when statement has succeeded.
  */
  DBUG_ASSERT(!(thd->in_sub_stmt));

  thd->merge_unsafe_rollback_flags();

  if (thd->transaction->stmt.ha_list)
  {
    res= ha_commit_trans(thd, FALSE);
    if (! thd->in_active_multi_stmt_transaction())
    {
      trans_reset_one_shot_chistics(thd);
    }
  }

  mysql_mutex_assert_not_owner(&LOCK_prepare_ordered);
  mysql_mutex_assert_not_owner(mysql_bin_log.get_log_lock());
  mysql_mutex_assert_not_owner(&LOCK_after_binlog_sync);
  mysql_mutex_assert_not_owner(&LOCK_commit_ordered);

    /*
      if res is non-zero, then ha_commit_trans has rolled back the
      transaction, so the hooks for rollback will be called.
    */
  if (res)
  {
#ifdef HAVE_REPLICATION
    repl_semisync_master.wait_after_rollback(thd, FALSE);
#endif
  }
  else
  {
#ifdef HAVE_REPLICATION
    repl_semisync_master.wait_after_commit(thd, FALSE);
#endif
  }

  /* In autocommit=1 mode the transaction should be marked as complete in P_S */
  DBUG_ASSERT(thd->in_active_multi_stmt_transaction() ||
              thd->m_transaction_psi == NULL);

  thd->transaction->stmt.reset();

  DBUG_RETURN(MY_TEST(res));
}


/**
  Rollback the single statement transaction.

  @param thd     Current thread

  @retval FALSE  Success
  @retval TRUE   Failure
*/
bool trans_rollback_stmt(THD *thd)
{
  DBUG_ENTER("trans_rollback_stmt");

  /*
    We currently don't invoke commit/rollback at end of
    a sub-statement.  In future, we perhaps should take
    a savepoint for each nested statement, and release the
    savepoint when statement has succeeded.
  */
  DBUG_ASSERT(! thd->in_sub_stmt);

  thd->merge_unsafe_rollback_flags();

  if (thd->transaction->stmt.ha_list)
  {
    ha_rollback_trans(thd, FALSE);
    if (! thd->in_active_multi_stmt_transaction())
      trans_reset_one_shot_chistics(thd);
  }

#ifdef HAVE_REPLICATION
  repl_semisync_master.wait_after_rollback(thd, FALSE);
#endif

  /* In autocommit=1 mode the transaction should be marked as complete in P_S */
  DBUG_ASSERT(thd->in_active_multi_stmt_transaction() ||
              thd->m_transaction_psi == NULL);

  thd->transaction->stmt.reset();

  DBUG_RETURN(FALSE);
}

/* Find a named savepoint in the current transaction. */
static SAVEPOINT **
find_savepoint(THD *thd, LEX_CSTRING name)
{
  SAVEPOINT **sv= &thd->transaction->savepoints;

  while (*sv)
  {
    if (system_charset_info->strnncoll(
                     (uchar *) name.str, name.length,
                     (uchar *) (*sv)->name, (*sv)->length) == 0)
      break;
    sv= &(*sv)->prev;
  }

  return sv;
}


/**
  Set a named transaction savepoint.

  @param thd    Current thread
  @param name   Savepoint name

  @retval FALSE  Success
  @retval TRUE   Failure
*/

bool trans_savepoint(THD *thd, LEX_CSTRING name)
{
  SAVEPOINT **sv, *newsv;
  DBUG_ENTER("trans_savepoint");

  if (!(thd->in_multi_stmt_transaction_mode() || thd->in_sub_stmt) ||
      !opt_using_transactions)
    DBUG_RETURN(FALSE);

  if (thd->transaction->xid_state.check_has_uncommitted_xa())
    DBUG_RETURN(TRUE);

  sv= find_savepoint(thd, name);

  if (*sv) /* old savepoint of the same name exists */
  {
    newsv= *sv;
    ha_release_savepoint(thd, *sv);
    *sv= (*sv)->prev;
  }
  else if ((newsv= (SAVEPOINT *) alloc_root(&thd->transaction->mem_root,
                                            savepoint_alloc_size)) == NULL)
  {
    my_error(ER_OUT_OF_RESOURCES, MYF(0));
    DBUG_RETURN(TRUE);
  }

  newsv->name= strmake_root(&thd->transaction->mem_root, name.str, name.length);
  newsv->length= (uint)name.length;

  /*
    if we'll get an error here, don't add new savepoint to the list.
    we'll lose a little bit of memory in transaction mem_root, but it'll
    be free'd when transaction ends anyway
  */
  if (unlikely(ha_savepoint(thd, newsv)))
    DBUG_RETURN(TRUE);

  newsv->prev= thd->transaction->savepoints;
  thd->transaction->savepoints= newsv;

  /*
    Remember locks acquired before the savepoint was set.
    They are used as a marker to only release locks acquired after
    the setting of this savepoint.
    Note: this works just fine if we're under LOCK TABLES,
    since mdl_savepoint() is guaranteed to be beyond
    the last locked table. This allows to release some
    locks acquired during LOCK TABLES.
  */
  newsv->mdl_savepoint= thd->mdl_context.mdl_savepoint();

  DBUG_RETURN(FALSE);
}


/**
  Rollback a transaction to the named savepoint.

  @note Modifications that the current transaction made to
        rows after the savepoint was set are undone in the
        rollback.

  @note Savepoints that were set at a later time than the
        named savepoint are deleted.

  @param thd    Current thread
  @param name   Savepoint name

  @retval FALSE  Success
  @retval TRUE   Failure
*/

bool trans_rollback_to_savepoint(THD *thd, LEX_CSTRING name)
{
  int res= FALSE;
  SAVEPOINT *sv= *find_savepoint(thd, name);
  DBUG_ENTER("trans_rollback_to_savepoint");

  if (sv == NULL)
  {
    my_error(ER_SP_DOES_NOT_EXIST, MYF(0), "SAVEPOINT", name.str);
    DBUG_RETURN(TRUE);
  }

  if (thd->transaction->xid_state.check_has_uncommitted_xa())
    DBUG_RETURN(TRUE);

  if (ha_rollback_to_savepoint(thd, sv))
    res= TRUE;
  else if (((thd->variables.option_bits & OPTION_BINLOG_THIS_TRX) ||
            thd->transaction->all.modified_non_trans_table) &&
           !thd->slave_thread)
    push_warning(thd, Sql_condition::WARN_LEVEL_WARN,
                 ER_WARNING_NOT_COMPLETE_ROLLBACK,
                 ER_THD(thd, ER_WARNING_NOT_COMPLETE_ROLLBACK));

  thd->transaction->savepoints= sv;

  if (res)
    /* An error occurred during rollback; we cannot release any MDL */;
  else if (thd->variables.sql_log_bin &&
           (WSREP_EMULATE_BINLOG_NNULL(thd) || mysql_bin_log.is_open()))
    /* In some cases (such as with non-transactional tables) we may
    choose to preserve events that were added after the SAVEPOINT,
    delimiting them by SAVEPOINT and ROLLBACK TO SAVEPOINT statements.
    Prematurely releasing MDL on such objects would break replication. */;
  else if (ha_rollback_to_savepoint_can_release_mdl(thd))
    thd->mdl_context.rollback_to_savepoint(sv->mdl_savepoint);

  DBUG_RETURN(MY_TEST(res));
}


/**
  Remove the named savepoint from the set of savepoints of
  the current transaction.

  @note No commit or rollback occurs. It is an error if the
        savepoint does not exist.

  @param thd    Current thread
  @param name   Savepoint name

  @retval FALSE  Success
  @retval TRUE   Failure
*/

bool trans_release_savepoint(THD *thd, LEX_CSTRING name)
{
  int res= FALSE;
  SAVEPOINT *sv= *find_savepoint(thd, name);
  DBUG_ENTER("trans_release_savepoint");

  if (sv == NULL)
  {
    my_error(ER_SP_DOES_NOT_EXIST, MYF(0), "SAVEPOINT", name.str);
    DBUG_RETURN(TRUE);
  }

  if (ha_release_savepoint(thd, sv))
    res= TRUE;

  thd->transaction->savepoints= sv->prev;

  DBUG_RETURN(MY_TEST(res));
}