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lmgr.c
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1 /*-------------------------------------------------------------------------
2  *
3  * lmgr.c
4  * POSTGRES lock manager code
5  *
6  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  *
10  * IDENTIFICATION
11  * src/backend/storage/lmgr/lmgr.c
12  *
13  *-------------------------------------------------------------------------
14  */
15 
16 #include "postgres.h"
17 
18 #include "access/subtrans.h"
19 #include "access/transam.h"
20 #include "access/xact.h"
21 #include "catalog/catalog.h"
22 #include "commands/progress.h"
23 #include "miscadmin.h"
24 #include "pgstat.h"
25 #include "storage/lmgr.h"
26 #include "storage/procarray.h"
27 #include "storage/sinvaladt.h"
28 #include "utils/inval.h"
29 
30 
31 /*
32  * Per-backend counter for generating speculative insertion tokens.
33  *
34  * This may wrap around, but that's OK as it's only used for the short
35  * duration between inserting a tuple and checking that there are no (unique)
36  * constraint violations. It's theoretically possible that a backend sees a
37  * tuple that was speculatively inserted by another backend, but before it has
38  * started waiting on the token, the other backend completes its insertion,
39  * and then performs 2^32 unrelated insertions. And after all that, the
40  * first backend finally calls SpeculativeInsertionLockAcquire(), with the
41  * intention of waiting for the first insertion to complete, but ends up
42  * waiting for the latest unrelated insertion instead. Even then, nothing
43  * particularly bad happens: in the worst case they deadlock, causing one of
44  * the transactions to abort.
45  */
47 
48 
49 /*
50  * Struct to hold context info for transaction lock waits.
51  *
52  * 'oper' is the operation that needs to wait for the other transaction; 'rel'
53  * and 'ctid' specify the address of the tuple being waited for.
54  */
55 typedef struct XactLockTableWaitInfo
56 {
61 
62 static void XactLockTableWaitErrorCb(void *arg);
63 
64 /*
65  * RelationInitLockInfo
66  * Initializes the lock information in a relation descriptor.
67  *
68  * relcache.c must call this during creation of any reldesc.
69  */
70 void
72 {
73  Assert(RelationIsValid(relation));
75 
76  relation->rd_lockInfo.lockRelId.relId = RelationGetRelid(relation);
77 
78  if (relation->rd_rel->relisshared)
80  else
82 }
83 
84 /*
85  * SetLocktagRelationOid
86  * Set up a locktag for a relation, given only relation OID
87  */
88 static inline void
90 {
91  Oid dbid;
92 
93  if (IsSharedRelation(relid))
94  dbid = InvalidOid;
95  else
96  dbid = MyDatabaseId;
97 
98  SET_LOCKTAG_RELATION(*tag, dbid, relid);
99 }
100 
101 /*
102  * LockRelationOid
103  *
104  * Lock a relation given only its OID. This should generally be used
105  * before attempting to open the relation's relcache entry.
106  */
107 void
108 LockRelationOid(Oid relid, LOCKMODE lockmode)
109 {
110  LOCKTAG tag;
111  LOCALLOCK *locallock;
112  LockAcquireResult res;
113 
114  SetLocktagRelationOid(&tag, relid);
115 
116  res = LockAcquireExtended(&tag, lockmode, false, false, true, &locallock);
117 
118  /*
119  * Now that we have the lock, check for invalidation messages, so that we
120  * will update or flush any stale relcache entry before we try to use it.
121  * RangeVarGetRelid() specifically relies on us for this. We can skip
122  * this in the not-uncommon case that we already had the same type of lock
123  * being requested, since then no one else could have modified the
124  * relcache entry in an undesirable way. (In the case where our own xact
125  * modifies the rel, the relcache update happens via
126  * CommandCounterIncrement, not here.)
127  *
128  * However, in corner cases where code acts on tables (usually catalogs)
129  * recursively, we might get here while still processing invalidation
130  * messages in some outer execution of this function or a sibling. The
131  * "cleared" status of the lock tells us whether we really are done
132  * absorbing relevant inval messages.
133  */
134  if (res != LOCKACQUIRE_ALREADY_CLEAR)
135  {
137  MarkLockClear(locallock);
138  }
139 }
140 
141 /*
142  * ConditionalLockRelationOid
143  *
144  * As above, but only lock if we can get the lock without blocking.
145  * Returns true iff the lock was acquired.
146  *
147  * NOTE: we do not currently need conditional versions of all the
148  * LockXXX routines in this file, but they could easily be added if needed.
149  */
150 bool
152 {
153  LOCKTAG tag;
154  LOCALLOCK *locallock;
155  LockAcquireResult res;
156 
157  SetLocktagRelationOid(&tag, relid);
158 
159  res = LockAcquireExtended(&tag, lockmode, false, true, true, &locallock);
160 
161  if (res == LOCKACQUIRE_NOT_AVAIL)
162  return false;
163 
164  /*
165  * Now that we have the lock, check for invalidation messages; see notes
166  * in LockRelationOid.
167  */
168  if (res != LOCKACQUIRE_ALREADY_CLEAR)
169  {
171  MarkLockClear(locallock);
172  }
173 
174  return true;
175 }
176 
177 /*
178  * UnlockRelationId
179  *
180  * Unlock, given a LockRelId. This is preferred over UnlockRelationOid
181  * for speed reasons.
182  */
183 void
185 {
186  LOCKTAG tag;
187 
188  SET_LOCKTAG_RELATION(tag, relid->dbId, relid->relId);
189 
190  LockRelease(&tag, lockmode, false);
191 }
192 
193 /*
194  * UnlockRelationOid
195  *
196  * Unlock, given only a relation Oid. Use UnlockRelationId if you can.
197  */
198 void
200 {
201  LOCKTAG tag;
202 
203  SetLocktagRelationOid(&tag, relid);
204 
205  LockRelease(&tag, lockmode, false);
206 }
207 
208 /*
209  * LockRelation
210  *
211  * This is a convenience routine for acquiring an additional lock on an
212  * already-open relation. Never try to do "relation_open(foo, NoLock)"
213  * and then lock with this.
214  */
215 void
216 LockRelation(Relation relation, LOCKMODE lockmode)
217 {
218  LOCKTAG tag;
219  LOCALLOCK *locallock;
220  LockAcquireResult res;
221 
223  relation->rd_lockInfo.lockRelId.dbId,
224  relation->rd_lockInfo.lockRelId.relId);
225 
226  res = LockAcquireExtended(&tag, lockmode, false, false, true, &locallock);
227 
228  /*
229  * Now that we have the lock, check for invalidation messages; see notes
230  * in LockRelationOid.
231  */
232  if (res != LOCKACQUIRE_ALREADY_CLEAR)
233  {
235  MarkLockClear(locallock);
236  }
237 }
238 
239 /*
240  * ConditionalLockRelation
241  *
242  * This is a convenience routine for acquiring an additional lock on an
243  * already-open relation. Never try to do "relation_open(foo, NoLock)"
244  * and then lock with this.
245  */
246 bool
248 {
249  LOCKTAG tag;
250  LOCALLOCK *locallock;
251  LockAcquireResult res;
252 
254  relation->rd_lockInfo.lockRelId.dbId,
255  relation->rd_lockInfo.lockRelId.relId);
256 
257  res = LockAcquireExtended(&tag, lockmode, false, true, true, &locallock);
258 
259  if (res == LOCKACQUIRE_NOT_AVAIL)
260  return false;
261 
262  /*
263  * Now that we have the lock, check for invalidation messages; see notes
264  * in LockRelationOid.
265  */
266  if (res != LOCKACQUIRE_ALREADY_CLEAR)
267  {
269  MarkLockClear(locallock);
270  }
271 
272  return true;
273 }
274 
275 /*
276  * UnlockRelation
277  *
278  * This is a convenience routine for unlocking a relation without also
279  * closing it.
280  */
281 void
282 UnlockRelation(Relation relation, LOCKMODE lockmode)
283 {
284  LOCKTAG tag;
285 
287  relation->rd_lockInfo.lockRelId.dbId,
288  relation->rd_lockInfo.lockRelId.relId);
289 
290  LockRelease(&tag, lockmode, false);
291 }
292 
293 /*
294  * CheckRelationLockedByMe
295  *
296  * Returns true if current transaction holds a lock on 'relation' of mode
297  * 'lockmode'. If 'orstronger' is true, a stronger lockmode is also OK.
298  * ("Stronger" is defined as "numerically higher", which is a bit
299  * semantically dubious but is OK for the purposes we use this for.)
300  */
301 bool
302 CheckRelationLockedByMe(Relation relation, LOCKMODE lockmode, bool orstronger)
303 {
304  LOCKTAG tag;
305 
307  relation->rd_lockInfo.lockRelId.dbId,
308  relation->rd_lockInfo.lockRelId.relId);
309 
310  if (LockHeldByMe(&tag, lockmode))
311  return true;
312 
313  if (orstronger)
314  {
315  LOCKMODE slockmode;
316 
317  for (slockmode = lockmode + 1;
318  slockmode <= MaxLockMode;
319  slockmode++)
320  {
321  if (LockHeldByMe(&tag, slockmode))
322  {
323 #ifdef NOT_USED
324  /* Sometimes this might be useful for debugging purposes */
325  elog(WARNING, "lock mode %s substituted for %s on relation %s",
326  GetLockmodeName(tag.locktag_lockmethodid, slockmode),
327  GetLockmodeName(tag.locktag_lockmethodid, lockmode),
328  RelationGetRelationName(relation));
329 #endif
330  return true;
331  }
332  }
333  }
334 
335  return false;
336 }
337 
338 /*
339  * LockHasWaitersRelation
340  *
341  * This is a function to check whether someone else is waiting for a
342  * lock which we are currently holding.
343  */
344 bool
346 {
347  LOCKTAG tag;
348 
350  relation->rd_lockInfo.lockRelId.dbId,
351  relation->rd_lockInfo.lockRelId.relId);
352 
353  return LockHasWaiters(&tag, lockmode, false);
354 }
355 
356 /*
357  * LockRelationIdForSession
358  *
359  * This routine grabs a session-level lock on the target relation. The
360  * session lock persists across transaction boundaries. It will be removed
361  * when UnlockRelationIdForSession() is called, or if an ereport(ERROR) occurs,
362  * or if the backend exits.
363  *
364  * Note that one should also grab a transaction-level lock on the rel
365  * in any transaction that actually uses the rel, to ensure that the
366  * relcache entry is up to date.
367  */
368 void
370 {
371  LOCKTAG tag;
372 
373  SET_LOCKTAG_RELATION(tag, relid->dbId, relid->relId);
374 
375  (void) LockAcquire(&tag, lockmode, true, false);
376 }
377 
378 /*
379  * UnlockRelationIdForSession
380  */
381 void
383 {
384  LOCKTAG tag;
385 
386  SET_LOCKTAG_RELATION(tag, relid->dbId, relid->relId);
387 
388  LockRelease(&tag, lockmode, true);
389 }
390 
391 /*
392  * LockRelationForExtension
393  *
394  * This lock tag is used to interlock addition of pages to relations.
395  * We need such locking because bufmgr/smgr definition of P_NEW is not
396  * race-condition-proof.
397  *
398  * We assume the caller is already holding some type of regular lock on
399  * the relation, so no AcceptInvalidationMessages call is needed here.
400  */
401 void
403 {
404  LOCKTAG tag;
405 
407  relation->rd_lockInfo.lockRelId.dbId,
408  relation->rd_lockInfo.lockRelId.relId);
409 
410  (void) LockAcquire(&tag, lockmode, false, false);
411 }
412 
413 /*
414  * ConditionalLockRelationForExtension
415  *
416  * As above, but only lock if we can get the lock without blocking.
417  * Returns true iff the lock was acquired.
418  */
419 bool
421 {
422  LOCKTAG tag;
423 
425  relation->rd_lockInfo.lockRelId.dbId,
426  relation->rd_lockInfo.lockRelId.relId);
427 
428  return (LockAcquire(&tag, lockmode, false, true) != LOCKACQUIRE_NOT_AVAIL);
429 }
430 
431 /*
432  * RelationExtensionLockWaiterCount
433  *
434  * Count the number of processes waiting for the given relation extension lock.
435  */
436 int
438 {
439  LOCKTAG tag;
440 
442  relation->rd_lockInfo.lockRelId.dbId,
443  relation->rd_lockInfo.lockRelId.relId);
444 
445  return LockWaiterCount(&tag);
446 }
447 
448 /*
449  * UnlockRelationForExtension
450  */
451 void
453 {
454  LOCKTAG tag;
455 
457  relation->rd_lockInfo.lockRelId.dbId,
458  relation->rd_lockInfo.lockRelId.relId);
459 
460  LockRelease(&tag, lockmode, false);
461 }
462 
463 /*
464  * LockPage
465  *
466  * Obtain a page-level lock. This is currently used by some index access
467  * methods to lock individual index pages.
468  */
469 void
470 LockPage(Relation relation, BlockNumber blkno, LOCKMODE lockmode)
471 {
472  LOCKTAG tag;
473 
474  SET_LOCKTAG_PAGE(tag,
475  relation->rd_lockInfo.lockRelId.dbId,
476  relation->rd_lockInfo.lockRelId.relId,
477  blkno);
478 
479  (void) LockAcquire(&tag, lockmode, false, false);
480 }
481 
482 /*
483  * ConditionalLockPage
484  *
485  * As above, but only lock if we can get the lock without blocking.
486  * Returns true iff the lock was acquired.
487  */
488 bool
490 {
491  LOCKTAG tag;
492 
493  SET_LOCKTAG_PAGE(tag,
494  relation->rd_lockInfo.lockRelId.dbId,
495  relation->rd_lockInfo.lockRelId.relId,
496  blkno);
497 
498  return (LockAcquire(&tag, lockmode, false, true) != LOCKACQUIRE_NOT_AVAIL);
499 }
500 
501 /*
502  * UnlockPage
503  */
504 void
505 UnlockPage(Relation relation, BlockNumber blkno, LOCKMODE lockmode)
506 {
507  LOCKTAG tag;
508 
509  SET_LOCKTAG_PAGE(tag,
510  relation->rd_lockInfo.lockRelId.dbId,
511  relation->rd_lockInfo.lockRelId.relId,
512  blkno);
513 
514  LockRelease(&tag, lockmode, false);
515 }
516 
517 /*
518  * LockTuple
519  *
520  * Obtain a tuple-level lock. This is used in a less-than-intuitive fashion
521  * because we can't afford to keep a separate lock in shared memory for every
522  * tuple. See heap_lock_tuple before using this!
523  */
524 void
525 LockTuple(Relation relation, ItemPointer tid, LOCKMODE lockmode)
526 {
527  LOCKTAG tag;
528 
529  SET_LOCKTAG_TUPLE(tag,
530  relation->rd_lockInfo.lockRelId.dbId,
531  relation->rd_lockInfo.lockRelId.relId,
534 
535  (void) LockAcquire(&tag, lockmode, false, false);
536 }
537 
538 /*
539  * ConditionalLockTuple
540  *
541  * As above, but only lock if we can get the lock without blocking.
542  * Returns true iff the lock was acquired.
543  */
544 bool
546 {
547  LOCKTAG tag;
548 
549  SET_LOCKTAG_TUPLE(tag,
550  relation->rd_lockInfo.lockRelId.dbId,
551  relation->rd_lockInfo.lockRelId.relId,
554 
555  return (LockAcquire(&tag, lockmode, false, true) != LOCKACQUIRE_NOT_AVAIL);
556 }
557 
558 /*
559  * UnlockTuple
560  */
561 void
562 UnlockTuple(Relation relation, ItemPointer tid, LOCKMODE lockmode)
563 {
564  LOCKTAG tag;
565 
566  SET_LOCKTAG_TUPLE(tag,
567  relation->rd_lockInfo.lockRelId.dbId,
568  relation->rd_lockInfo.lockRelId.relId,
571 
572  LockRelease(&tag, lockmode, false);
573 }
574 
575 /*
576  * XactLockTableInsert
577  *
578  * Insert a lock showing that the given transaction ID is running ---
579  * this is done when an XID is acquired by a transaction or subtransaction.
580  * The lock can then be used to wait for the transaction to finish.
581  */
582 void
584 {
585  LOCKTAG tag;
586 
587  SET_LOCKTAG_TRANSACTION(tag, xid);
588 
589  (void) LockAcquire(&tag, ExclusiveLock, false, false);
590 }
591 
592 /*
593  * XactLockTableDelete
594  *
595  * Delete the lock showing that the given transaction ID is running.
596  * (This is never used for main transaction IDs; those locks are only
597  * released implicitly at transaction end. But we do use it for subtrans IDs.)
598  */
599 void
601 {
602  LOCKTAG tag;
603 
604  SET_LOCKTAG_TRANSACTION(tag, xid);
605 
606  LockRelease(&tag, ExclusiveLock, false);
607 }
608 
609 /*
610  * XactLockTableWait
611  *
612  * Wait for the specified transaction to commit or abort. If an operation
613  * is specified, an error context callback is set up. If 'oper' is passed as
614  * None, no error context callback is set up.
615  *
616  * Note that this does the right thing for subtransactions: if we wait on a
617  * subtransaction, we will exit as soon as it aborts or its top parent commits.
618  * It takes some extra work to ensure this, because to save on shared memory
619  * the XID lock of a subtransaction is released when it ends, whether
620  * successfully or unsuccessfully. So we have to check if it's "still running"
621  * and if so wait for its parent.
622  */
623 void
625  XLTW_Oper oper)
626 {
627  LOCKTAG tag;
630  bool first = true;
631 
632  /*
633  * If an operation is specified, set up our verbose error context
634  * callback.
635  */
636  if (oper != XLTW_None)
637  {
638  Assert(RelationIsValid(rel));
639  Assert(ItemPointerIsValid(ctid));
640 
641  info.rel = rel;
642  info.ctid = ctid;
643  info.oper = oper;
644 
646  callback.arg = &info;
647  callback.previous = error_context_stack;
649  }
650 
651  for (;;)
652  {
655 
656  SET_LOCKTAG_TRANSACTION(tag, xid);
657 
658  (void) LockAcquire(&tag, ShareLock, false, false);
659 
660  LockRelease(&tag, ShareLock, false);
661 
662  if (!TransactionIdIsInProgress(xid))
663  break;
664 
665  /*
666  * If the Xid belonged to a subtransaction, then the lock would have
667  * gone away as soon as it was finished; for correct tuple visibility,
668  * the right action is to wait on its parent transaction to go away.
669  * But instead of going levels up one by one, we can just wait for the
670  * topmost transaction to finish with the same end result, which also
671  * incurs less locktable traffic.
672  *
673  * Some uses of this function don't involve tuple visibility -- such
674  * as when building snapshots for logical decoding. It is possible to
675  * see a transaction in ProcArray before it registers itself in the
676  * locktable. The topmost transaction in that case is the same xid,
677  * so we try again after a short sleep. (Don't sleep the first time
678  * through, to avoid slowing down the normal case.)
679  */
680  if (!first)
681  pg_usleep(1000L);
682  first = false;
684  }
685 
686  if (oper != XLTW_None)
687  error_context_stack = callback.previous;
688 }
689 
690 /*
691  * ConditionalXactLockTableWait
692  *
693  * As above, but only lock if we can get the lock without blocking.
694  * Returns true if the lock was acquired.
695  */
696 bool
698 {
699  LOCKTAG tag;
700  bool first = true;
701 
702  for (;;)
703  {
706 
707  SET_LOCKTAG_TRANSACTION(tag, xid);
708 
709  if (LockAcquire(&tag, ShareLock, false, true) == LOCKACQUIRE_NOT_AVAIL)
710  return false;
711 
712  LockRelease(&tag, ShareLock, false);
713 
714  if (!TransactionIdIsInProgress(xid))
715  break;
716 
717  /* See XactLockTableWait about this case */
718  if (!first)
719  pg_usleep(1000L);
720  first = false;
722  }
723 
724  return true;
725 }
726 
727 /*
728  * SpeculativeInsertionLockAcquire
729  *
730  * Insert a lock showing that the given transaction ID is inserting a tuple,
731  * but hasn't yet decided whether it's going to keep it. The lock can then be
732  * used to wait for the decision to go ahead with the insertion, or aborting
733  * it.
734  *
735  * The token is used to distinguish multiple insertions by the same
736  * transaction. It is returned to caller.
737  */
738 uint32
740 {
741  LOCKTAG tag;
742 
744 
745  /*
746  * Check for wrap-around. Zero means no token is held, so don't use that.
747  */
748  if (speculativeInsertionToken == 0)
750 
752 
753  (void) LockAcquire(&tag, ExclusiveLock, false, false);
754 
756 }
757 
758 /*
759  * SpeculativeInsertionLockRelease
760  *
761  * Delete the lock showing that the given transaction is speculatively
762  * inserting a tuple.
763  */
764 void
766 {
767  LOCKTAG tag;
768 
770 
771  LockRelease(&tag, ExclusiveLock, false);
772 }
773 
774 /*
775  * SpeculativeInsertionWait
776  *
777  * Wait for the specified transaction to finish or abort the insertion of a
778  * tuple.
779  */
780 void
782 {
783  LOCKTAG tag;
784 
785  SET_LOCKTAG_SPECULATIVE_INSERTION(tag, xid, token);
786 
788  Assert(token != 0);
789 
790  (void) LockAcquire(&tag, ShareLock, false, false);
791  LockRelease(&tag, ShareLock, false);
792 }
793 
794 /*
795  * XactLockTableWaitErrorCb
796  * Error context callback for transaction lock waits.
797  */
798 static void
800 {
802 
803  /*
804  * We would like to print schema name too, but that would require a
805  * syscache lookup.
806  */
807  if (info->oper != XLTW_None &&
808  ItemPointerIsValid(info->ctid) && RelationIsValid(info->rel))
809  {
810  const char *cxt;
811 
812  switch (info->oper)
813  {
814  case XLTW_Update:
815  cxt = gettext_noop("while updating tuple (%u,%u) in relation \"%s\"");
816  break;
817  case XLTW_Delete:
818  cxt = gettext_noop("while deleting tuple (%u,%u) in relation \"%s\"");
819  break;
820  case XLTW_Lock:
821  cxt = gettext_noop("while locking tuple (%u,%u) in relation \"%s\"");
822  break;
823  case XLTW_LockUpdated:
824  cxt = gettext_noop("while locking updated version (%u,%u) of tuple in relation \"%s\"");
825  break;
826  case XLTW_InsertIndex:
827  cxt = gettext_noop("while inserting index tuple (%u,%u) in relation \"%s\"");
828  break;
830  cxt = gettext_noop("while checking uniqueness of tuple (%u,%u) in relation \"%s\"");
831  break;
832  case XLTW_FetchUpdated:
833  cxt = gettext_noop("while rechecking updated tuple (%u,%u) in relation \"%s\"");
834  break;
836  cxt = gettext_noop("while checking exclusion constraint on tuple (%u,%u) in relation \"%s\"");
837  break;
838 
839  default:
840  return;
841  }
842 
843  errcontext(cxt,
847  }
848 }
849 
850 /*
851  * WaitForLockersMultiple
852  * Wait until no transaction holds locks that conflict with the given
853  * locktags at the given lockmode.
854  *
855  * To do this, obtain the current list of lockers, and wait on their VXIDs
856  * until they are finished.
857  *
858  * Note we don't try to acquire the locks on the given locktags, only the VXIDs
859  * of its lock holders; if somebody grabs a conflicting lock on the objects
860  * after we obtained our initial list of lockers, we will not wait for them.
861  */
862 void
863 WaitForLockersMultiple(List *locktags, LOCKMODE lockmode, bool progress)
864 {
865  List *holders = NIL;
866  ListCell *lc;
867  int total = 0;
868  int done = 0;
869 
870  /* Done if no locks to wait for */
871  if (list_length(locktags) == 0)
872  return;
873 
874  /* Collect the transactions we need to wait on */
875  foreach(lc, locktags)
876  {
877  LOCKTAG *locktag = lfirst(lc);
878  int count;
879 
880  holders = lappend(holders,
881  GetLockConflicts(locktag, lockmode,
882  progress ? &count : NULL));
883  if (progress)
884  total += count;
885  }
886 
887  if (progress)
889 
890  /*
891  * Note: GetLockConflicts() never reports our own xid, hence we need not
892  * check for that. Also, prepared xacts are not reported, which is fine
893  * since they certainly aren't going to do anything anymore.
894  */
895 
896  /* Finally wait for each such transaction to complete */
897  foreach(lc, holders)
898  {
899  VirtualTransactionId *lockholders = lfirst(lc);
900 
901  while (VirtualTransactionIdIsValid(*lockholders))
902  {
903  /* If requested, publish who we're going to wait for. */
904  if (progress)
905  {
906  PGPROC *holder = BackendIdGetProc(lockholders->backendId);
907 
908  if (holder)
910  holder->pid);
911  }
912  VirtualXactLock(*lockholders, true);
913  lockholders++;
914 
915  if (progress)
917  }
918  }
919  if (progress)
920  {
921  const int index[] = {
925  };
926  const int64 values[] = {
927  0, 0, 0
928  };
929 
930  pgstat_progress_update_multi_param(3, index, values);
931  }
932 
933  list_free_deep(holders);
934 }
935 
936 /*
937  * WaitForLockers
938  *
939  * Same as WaitForLockersMultiple, for a single lock tag.
940  */
941 void
942 WaitForLockers(LOCKTAG heaplocktag, LOCKMODE lockmode, bool progress)
943 {
944  List *l;
945 
946  l = list_make1(&heaplocktag);
947  WaitForLockersMultiple(l, lockmode, progress);
948  list_free(l);
949 }
950 
951 
952 /*
953  * LockDatabaseObject
954  *
955  * Obtain a lock on a general object of the current database. Don't use
956  * this for shared objects (such as tablespaces). It's unwise to apply it
957  * to relations, also, since a lock taken this way will NOT conflict with
958  * locks taken via LockRelation and friends.
959  */
960 void
961 LockDatabaseObject(Oid classid, Oid objid, uint16 objsubid,
962  LOCKMODE lockmode)
963 {
964  LOCKTAG tag;
965 
966  SET_LOCKTAG_OBJECT(tag,
967  MyDatabaseId,
968  classid,
969  objid,
970  objsubid);
971 
972  (void) LockAcquire(&tag, lockmode, false, false);
973 
974  /* Make sure syscaches are up-to-date with any changes we waited for */
976 }
977 
978 /*
979  * UnlockDatabaseObject
980  */
981 void
982 UnlockDatabaseObject(Oid classid, Oid objid, uint16 objsubid,
983  LOCKMODE lockmode)
984 {
985  LOCKTAG tag;
986 
987  SET_LOCKTAG_OBJECT(tag,
988  MyDatabaseId,
989  classid,
990  objid,
991  objsubid);
992 
993  LockRelease(&tag, lockmode, false);
994 }
995 
996 /*
997  * LockSharedObject
998  *
999  * Obtain a lock on a shared-across-databases object.
1000  */
1001 void
1002 LockSharedObject(Oid classid, Oid objid, uint16 objsubid,
1003  LOCKMODE lockmode)
1004 {
1005  LOCKTAG tag;
1006 
1007  SET_LOCKTAG_OBJECT(tag,
1008  InvalidOid,
1009  classid,
1010  objid,
1011  objsubid);
1012 
1013  (void) LockAcquire(&tag, lockmode, false, false);
1014 
1015  /* Make sure syscaches are up-to-date with any changes we waited for */
1017 }
1018 
1019 /*
1020  * UnlockSharedObject
1021  */
1022 void
1023 UnlockSharedObject(Oid classid, Oid objid, uint16 objsubid,
1024  LOCKMODE lockmode)
1025 {
1026  LOCKTAG tag;
1027 
1028  SET_LOCKTAG_OBJECT(tag,
1029  InvalidOid,
1030  classid,
1031  objid,
1032  objsubid);
1033 
1034  LockRelease(&tag, lockmode, false);
1035 }
1036 
1037 /*
1038  * LockSharedObjectForSession
1039  *
1040  * Obtain a session-level lock on a shared-across-databases object.
1041  * See LockRelationIdForSession for notes about session-level locks.
1042  */
1043 void
1044 LockSharedObjectForSession(Oid classid, Oid objid, uint16 objsubid,
1045  LOCKMODE lockmode)
1046 {
1047  LOCKTAG tag;
1048 
1049  SET_LOCKTAG_OBJECT(tag,
1050  InvalidOid,
1051  classid,
1052  objid,
1053  objsubid);
1054 
1055  (void) LockAcquire(&tag, lockmode, true, false);
1056 }
1057 
1058 /*
1059  * UnlockSharedObjectForSession
1060  */
1061 void
1062 UnlockSharedObjectForSession(Oid classid, Oid objid, uint16 objsubid,
1063  LOCKMODE lockmode)
1064 {
1065  LOCKTAG tag;
1066 
1067  SET_LOCKTAG_OBJECT(tag,
1068  InvalidOid,
1069  classid,
1070  objid,
1071  objsubid);
1072 
1073  LockRelease(&tag, lockmode, true);
1074 }
1075 
1076 
1077 /*
1078  * Append a description of a lockable object to buf.
1079  *
1080  * Ideally we would print names for the numeric values, but that requires
1081  * getting locks on system tables, which might cause problems since this is
1082  * typically used to report deadlock situations.
1083  */
1084 void
1086 {
1087  switch ((LockTagType) tag->locktag_type)
1088  {
1089  case LOCKTAG_RELATION:
1090  appendStringInfo(buf,
1091  _("relation %u of database %u"),
1092  tag->locktag_field2,
1093  tag->locktag_field1);
1094  break;
1096  appendStringInfo(buf,
1097  _("extension of relation %u of database %u"),
1098  tag->locktag_field2,
1099  tag->locktag_field1);
1100  break;
1101  case LOCKTAG_PAGE:
1102  appendStringInfo(buf,
1103  _("page %u of relation %u of database %u"),
1104  tag->locktag_field3,
1105  tag->locktag_field2,
1106  tag->locktag_field1);
1107  break;
1108  case LOCKTAG_TUPLE:
1109  appendStringInfo(buf,
1110  _("tuple (%u,%u) of relation %u of database %u"),
1111  tag->locktag_field3,
1112  tag->locktag_field4,
1113  tag->locktag_field2,
1114  tag->locktag_field1);
1115  break;
1116  case LOCKTAG_TRANSACTION:
1117  appendStringInfo(buf,
1118  _("transaction %u"),
1119  tag->locktag_field1);
1120  break;
1122  appendStringInfo(buf,
1123  _("virtual transaction %d/%u"),
1124  tag->locktag_field1,
1125  tag->locktag_field2);
1126  break;
1128  appendStringInfo(buf,
1129  _("speculative token %u of transaction %u"),
1130  tag->locktag_field2,
1131  tag->locktag_field1);
1132  break;
1133  case LOCKTAG_OBJECT:
1134  appendStringInfo(buf,
1135  _("object %u of class %u of database %u"),
1136  tag->locktag_field3,
1137  tag->locktag_field2,
1138  tag->locktag_field1);
1139  break;
1140  case LOCKTAG_USERLOCK:
1141  /* reserved for old contrib code, now on pgfoundry */
1142  appendStringInfo(buf,
1143  _("user lock [%u,%u,%u]"),
1144  tag->locktag_field1,
1145  tag->locktag_field2,
1146  tag->locktag_field3);
1147  break;
1148  case LOCKTAG_ADVISORY:
1149  appendStringInfo(buf,
1150  _("advisory lock [%u,%u,%u,%u]"),
1151  tag->locktag_field1,
1152  tag->locktag_field2,
1153  tag->locktag_field3,
1154  tag->locktag_field4);
1155  break;
1156  default:
1157  appendStringInfo(buf,
1158  _("unrecognized locktag type %d"),
1159  (int) tag->locktag_type);
1160  break;
1161  }
1162 }
1163 
1164 /*
1165  * GetLockNameFromTagType
1166  *
1167  * Given locktag type, return the corresponding lock name.
1168  */
1169 const char *
1171 {
1172  if (locktag_type > LOCKTAG_LAST_TYPE)
1173  return "???";
1174  return LockTagTypeNames[locktag_type];
1175 }
#define SET_LOCKTAG_TUPLE(locktag, dboid, reloid, blocknum, offnum)
Definition: lock.h:208
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#define MaxLockMode
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