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lockfuncs.c
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1 /*-------------------------------------------------------------------------
2  *
3  * lockfuncs.c
4  * Functions for SQL access to various lock-manager capabilities.
5  *
6  * Copyright (c) 2002-2024, PostgreSQL Global Development Group
7  *
8  * IDENTIFICATION
9  * src/backend/utils/adt/lockfuncs.c
10  *
11  *-------------------------------------------------------------------------
12  */
13 #include "postgres.h"
14 
15 #include "access/htup_details.h"
16 #include "funcapi.h"
17 #include "miscadmin.h"
19 #include "utils/array.h"
20 #include "utils/builtins.h"
21 
22 
23 /*
24  * This must match enum LockTagType! Also, be sure to document any changes
25  * in the docs for the pg_locks view and update the WaitEventLOCK section in
26  * src/backend/utils/activity/wait_event_names.txt.
27  */
28 const char *const LockTagTypeNames[] = {
29  "relation",
30  "extend",
31  "frozenid",
32  "page",
33  "tuple",
34  "transactionid",
35  "virtualxid",
36  "spectoken",
37  "object",
38  "userlock",
39  "advisory",
40  "applytransaction"
41 };
42 
44  "array length mismatch");
45 
46 /* This must match enum PredicateLockTargetType (predicate_internals.h) */
47 static const char *const PredicateLockTagTypeNames[] = {
48  "relation",
49  "page",
50  "tuple"
51 };
52 
54  "array length mismatch");
55 
56 /* Working status for pg_lock_status */
57 typedef struct
58 {
59  LockData *lockData; /* state data from lmgr */
60  int currIdx; /* current PROCLOCK index */
61  PredicateLockData *predLockData; /* state data for pred locks */
62  int predLockIdx; /* current index for pred lock */
64 
65 /* Number of columns in pg_locks output */
66 #define NUM_LOCK_STATUS_COLUMNS 16
67 
68 /*
69  * VXIDGetDatum - Construct a text representation of a VXID
70  *
71  * This is currently only used in pg_lock_status, so we put it here.
72  */
73 static Datum
75 {
76  /*
77  * The representation is "<procNumber>/<lxid>", decimal and unsigned
78  * decimal respectively. Note that elog.c also knows how to format a
79  * vxid.
80  */
81  char vxidstr[32];
82 
83  snprintf(vxidstr, sizeof(vxidstr), "%d/%u", procNumber, lxid);
84 
85  return CStringGetTextDatum(vxidstr);
86 }
87 
88 
89 /*
90  * pg_lock_status - produce a view with one row per held or awaited lock mode
91  */
92 Datum
94 {
95  FuncCallContext *funcctx;
96  PG_Lock_Status *mystatus;
97  LockData *lockData;
98  PredicateLockData *predLockData;
99 
100  if (SRF_IS_FIRSTCALL())
101  {
102  TupleDesc tupdesc;
103  MemoryContext oldcontext;
104 
105  /* create a function context for cross-call persistence */
106  funcctx = SRF_FIRSTCALL_INIT();
107 
108  /*
109  * switch to memory context appropriate for multiple function calls
110  */
111  oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
112 
113  /* build tupdesc for result tuples */
114  /* this had better match function's declaration in pg_proc.h */
116  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "locktype",
117  TEXTOID, -1, 0);
118  TupleDescInitEntry(tupdesc, (AttrNumber) 2, "database",
119  OIDOID, -1, 0);
120  TupleDescInitEntry(tupdesc, (AttrNumber) 3, "relation",
121  OIDOID, -1, 0);
122  TupleDescInitEntry(tupdesc, (AttrNumber) 4, "page",
123  INT4OID, -1, 0);
124  TupleDescInitEntry(tupdesc, (AttrNumber) 5, "tuple",
125  INT2OID, -1, 0);
126  TupleDescInitEntry(tupdesc, (AttrNumber) 6, "virtualxid",
127  TEXTOID, -1, 0);
128  TupleDescInitEntry(tupdesc, (AttrNumber) 7, "transactionid",
129  XIDOID, -1, 0);
130  TupleDescInitEntry(tupdesc, (AttrNumber) 8, "classid",
131  OIDOID, -1, 0);
132  TupleDescInitEntry(tupdesc, (AttrNumber) 9, "objid",
133  OIDOID, -1, 0);
134  TupleDescInitEntry(tupdesc, (AttrNumber) 10, "objsubid",
135  INT2OID, -1, 0);
136  TupleDescInitEntry(tupdesc, (AttrNumber) 11, "virtualtransaction",
137  TEXTOID, -1, 0);
138  TupleDescInitEntry(tupdesc, (AttrNumber) 12, "pid",
139  INT4OID, -1, 0);
140  TupleDescInitEntry(tupdesc, (AttrNumber) 13, "mode",
141  TEXTOID, -1, 0);
142  TupleDescInitEntry(tupdesc, (AttrNumber) 14, "granted",
143  BOOLOID, -1, 0);
144  TupleDescInitEntry(tupdesc, (AttrNumber) 15, "fastpath",
145  BOOLOID, -1, 0);
146  TupleDescInitEntry(tupdesc, (AttrNumber) 16, "waitstart",
147  TIMESTAMPTZOID, -1, 0);
148 
149  funcctx->tuple_desc = BlessTupleDesc(tupdesc);
150 
151  /*
152  * Collect all the locking information that we will format and send
153  * out as a result set.
154  */
155  mystatus = (PG_Lock_Status *) palloc(sizeof(PG_Lock_Status));
156  funcctx->user_fctx = (void *) mystatus;
157 
158  mystatus->lockData = GetLockStatusData();
159  mystatus->currIdx = 0;
161  mystatus->predLockIdx = 0;
162 
163  MemoryContextSwitchTo(oldcontext);
164  }
165 
166  funcctx = SRF_PERCALL_SETUP();
167  mystatus = (PG_Lock_Status *) funcctx->user_fctx;
168  lockData = mystatus->lockData;
169 
170  while (mystatus->currIdx < lockData->nelements)
171  {
172  bool granted;
173  LOCKMODE mode = 0;
174  const char *locktypename;
175  char tnbuf[32];
177  bool nulls[NUM_LOCK_STATUS_COLUMNS] = {0};
178  HeapTuple tuple;
179  Datum result;
180  LockInstanceData *instance;
181 
182  instance = &(lockData->locks[mystatus->currIdx]);
183 
184  /*
185  * Look to see if there are any held lock modes in this PROCLOCK. If
186  * so, report, and destructively modify lockData so we don't report
187  * again.
188  */
189  granted = false;
190  if (instance->holdMask)
191  {
192  for (mode = 0; mode < MAX_LOCKMODES; mode++)
193  {
194  if (instance->holdMask & LOCKBIT_ON(mode))
195  {
196  granted = true;
197  instance->holdMask &= LOCKBIT_OFF(mode);
198  break;
199  }
200  }
201  }
202 
203  /*
204  * If no (more) held modes to report, see if PROC is waiting for a
205  * lock on this lock.
206  */
207  if (!granted)
208  {
209  if (instance->waitLockMode != NoLock)
210  {
211  /* Yes, so report it with proper mode */
212  mode = instance->waitLockMode;
213 
214  /*
215  * We are now done with this PROCLOCK, so advance pointer to
216  * continue with next one on next call.
217  */
218  mystatus->currIdx++;
219  }
220  else
221  {
222  /*
223  * Okay, we've displayed all the locks associated with this
224  * PROCLOCK, proceed to the next one.
225  */
226  mystatus->currIdx++;
227  continue;
228  }
229  }
230 
231  /*
232  * Form tuple with appropriate data.
233  */
234 
235  if (instance->locktag.locktag_type <= LOCKTAG_LAST_TYPE)
236  locktypename = LockTagTypeNames[instance->locktag.locktag_type];
237  else
238  {
239  snprintf(tnbuf, sizeof(tnbuf), "unknown %d",
240  (int) instance->locktag.locktag_type);
241  locktypename = tnbuf;
242  }
243  values[0] = CStringGetTextDatum(locktypename);
244 
245  switch ((LockTagType) instance->locktag.locktag_type)
246  {
247  case LOCKTAG_RELATION:
251  nulls[3] = true;
252  nulls[4] = true;
253  nulls[5] = true;
254  nulls[6] = true;
255  nulls[7] = true;
256  nulls[8] = true;
257  nulls[9] = true;
258  break;
261  nulls[2] = true;
262  nulls[3] = true;
263  nulls[4] = true;
264  nulls[5] = true;
265  nulls[6] = true;
266  nulls[7] = true;
267  nulls[8] = true;
268  nulls[9] = true;
269  break;
270  case LOCKTAG_PAGE:
274  nulls[4] = true;
275  nulls[5] = true;
276  nulls[6] = true;
277  nulls[7] = true;
278  nulls[8] = true;
279  nulls[9] = true;
280  break;
281  case LOCKTAG_TUPLE:
286  nulls[5] = true;
287  nulls[6] = true;
288  nulls[7] = true;
289  nulls[8] = true;
290  nulls[9] = true;
291  break;
292  case LOCKTAG_TRANSACTION:
293  values[6] =
295  nulls[1] = true;
296  nulls[2] = true;
297  nulls[3] = true;
298  nulls[4] = true;
299  nulls[5] = true;
300  nulls[7] = true;
301  nulls[8] = true;
302  nulls[9] = true;
303  break;
305  values[5] = VXIDGetDatum(instance->locktag.locktag_field1,
306  instance->locktag.locktag_field2);
307  nulls[1] = true;
308  nulls[2] = true;
309  nulls[3] = true;
310  nulls[4] = true;
311  nulls[6] = true;
312  nulls[7] = true;
313  nulls[8] = true;
314  nulls[9] = true;
315  break;
317  values[6] =
320  nulls[1] = true;
321  nulls[2] = true;
322  nulls[3] = true;
323  nulls[4] = true;
324  nulls[5] = true;
325  nulls[7] = true;
326  nulls[9] = true;
327  break;
332  values[9] = Int16GetDatum(instance->locktag.locktag_field4);
333  nulls[2] = true;
334  nulls[3] = true;
335  nulls[4] = true;
336  nulls[5] = true;
337  nulls[7] = true;
338  break;
339  case LOCKTAG_OBJECT:
340  case LOCKTAG_USERLOCK:
341  case LOCKTAG_ADVISORY:
342  default: /* treat unknown locktags like OBJECT */
346  values[9] = Int16GetDatum(instance->locktag.locktag_field4);
347  nulls[2] = true;
348  nulls[3] = true;
349  nulls[4] = true;
350  nulls[5] = true;
351  nulls[6] = true;
352  break;
353  }
354 
355  values[10] = VXIDGetDatum(instance->vxid.procNumber, instance->vxid.localTransactionId);
356  if (instance->pid != 0)
357  values[11] = Int32GetDatum(instance->pid);
358  else
359  nulls[11] = true;
361  values[13] = BoolGetDatum(granted);
362  values[14] = BoolGetDatum(instance->fastpath);
363  if (!granted && instance->waitStart != 0)
364  values[15] = TimestampTzGetDatum(instance->waitStart);
365  else
366  nulls[15] = true;
367 
368  tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
369  result = HeapTupleGetDatum(tuple);
370  SRF_RETURN_NEXT(funcctx, result);
371  }
372 
373  /*
374  * Have returned all regular locks. Now start on the SIREAD predicate
375  * locks.
376  */
377  predLockData = mystatus->predLockData;
378  if (mystatus->predLockIdx < predLockData->nelements)
379  {
380  PredicateLockTargetType lockType;
381 
382  PREDICATELOCKTARGETTAG *predTag = &(predLockData->locktags[mystatus->predLockIdx]);
383  SERIALIZABLEXACT *xact = &(predLockData->xacts[mystatus->predLockIdx]);
385  bool nulls[NUM_LOCK_STATUS_COLUMNS] = {0};
386  HeapTuple tuple;
387  Datum result;
388 
389  mystatus->predLockIdx++;
390 
391  /*
392  * Form tuple with appropriate data.
393  */
394 
395  /* lock type */
396  lockType = GET_PREDICATELOCKTARGETTAG_TYPE(*predTag);
397 
399 
400  /* lock target */
401  values[1] = GET_PREDICATELOCKTARGETTAG_DB(*predTag);
403  if (lockType == PREDLOCKTAG_TUPLE)
405  else
406  nulls[4] = true;
407  if ((lockType == PREDLOCKTAG_TUPLE) ||
408  (lockType == PREDLOCKTAG_PAGE))
410  else
411  nulls[3] = true;
412 
413  /* these fields are targets for other types of locks */
414  nulls[5] = true; /* virtualxid */
415  nulls[6] = true; /* transactionid */
416  nulls[7] = true; /* classid */
417  nulls[8] = true; /* objid */
418  nulls[9] = true; /* objsubid */
419 
420  /* lock holder */
421  values[10] = VXIDGetDatum(xact->vxid.procNumber,
422  xact->vxid.localTransactionId);
423  if (xact->pid != 0)
424  values[11] = Int32GetDatum(xact->pid);
425  else
426  nulls[11] = true;
427 
428  /*
429  * Lock mode. Currently all predicate locks are SIReadLocks, which are
430  * always held (never waiting) and have no fast path
431  */
432  values[12] = CStringGetTextDatum("SIReadLock");
433  values[13] = BoolGetDatum(true);
434  values[14] = BoolGetDatum(false);
435  nulls[15] = true;
436 
437  tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
438  result = HeapTupleGetDatum(tuple);
439  SRF_RETURN_NEXT(funcctx, result);
440  }
441 
442  SRF_RETURN_DONE(funcctx);
443 }
444 
445 
446 /*
447  * pg_blocking_pids - produce an array of the PIDs blocking given PID
448  *
449  * The reported PIDs are those that hold a lock conflicting with blocked_pid's
450  * current request (hard block), or are requesting such a lock and are ahead
451  * of blocked_pid in the lock's wait queue (soft block).
452  *
453  * In parallel-query cases, we report all PIDs blocking any member of the
454  * given PID's lock group, and the reported PIDs are those of the blocking
455  * PIDs' lock group leaders. This allows callers to compare the result to
456  * lists of clients' pg_backend_pid() results even during a parallel query.
457  *
458  * Parallel query makes it possible for there to be duplicate PIDs in the
459  * result (either because multiple waiters are blocked by same PID, or
460  * because multiple blockers have same group leader PID). We do not bother
461  * to eliminate such duplicates from the result.
462  *
463  * We need not consider predicate locks here, since those don't block anything.
464  */
465 Datum
467 {
468  int blocked_pid = PG_GETARG_INT32(0);
469  Datum *arrayelems;
470  int narrayelems;
471  BlockedProcsData *lockData; /* state data from lmgr */
472  int i,
473  j;
474 
475  /* Collect a snapshot of lock manager state */
476  lockData = GetBlockerStatusData(blocked_pid);
477 
478  /* We can't need more output entries than there are reported PROCLOCKs */
479  arrayelems = (Datum *) palloc(lockData->nlocks * sizeof(Datum));
480  narrayelems = 0;
481 
482  /* For each blocked proc in the lock group ... */
483  for (i = 0; i < lockData->nprocs; i++)
484  {
485  BlockedProcData *bproc = &lockData->procs[i];
486  LockInstanceData *instances = &lockData->locks[bproc->first_lock];
487  int *preceding_waiters = &lockData->waiter_pids[bproc->first_waiter];
488  LockInstanceData *blocked_instance;
489  LockMethod lockMethodTable;
490  int conflictMask;
491 
492  /*
493  * Locate the blocked proc's own entry in the LockInstanceData array.
494  * There should be exactly one matching entry.
495  */
496  blocked_instance = NULL;
497  for (j = 0; j < bproc->num_locks; j++)
498  {
499  LockInstanceData *instance = &(instances[j]);
500 
501  if (instance->pid == bproc->pid)
502  {
503  Assert(blocked_instance == NULL);
504  blocked_instance = instance;
505  }
506  }
507  Assert(blocked_instance != NULL);
508 
509  lockMethodTable = GetLockTagsMethodTable(&(blocked_instance->locktag));
510  conflictMask = lockMethodTable->conflictTab[blocked_instance->waitLockMode];
511 
512  /* Now scan the PROCLOCK data for conflicting procs */
513  for (j = 0; j < bproc->num_locks; j++)
514  {
515  LockInstanceData *instance = &(instances[j]);
516 
517  /* A proc never blocks itself, so ignore that entry */
518  if (instance == blocked_instance)
519  continue;
520  /* Members of same lock group never block each other, either */
521  if (instance->leaderPid == blocked_instance->leaderPid)
522  continue;
523 
524  if (conflictMask & instance->holdMask)
525  {
526  /* hard block: blocked by lock already held by this entry */
527  }
528  else if (instance->waitLockMode != NoLock &&
529  (conflictMask & LOCKBIT_ON(instance->waitLockMode)))
530  {
531  /* conflict in lock requests; who's in front in wait queue? */
532  bool ahead = false;
533  int k;
534 
535  for (k = 0; k < bproc->num_waiters; k++)
536  {
537  if (preceding_waiters[k] == instance->pid)
538  {
539  /* soft block: this entry is ahead of blocked proc */
540  ahead = true;
541  break;
542  }
543  }
544  if (!ahead)
545  continue; /* not blocked by this entry */
546  }
547  else
548  {
549  /* not blocked by this entry */
550  continue;
551  }
552 
553  /* blocked by this entry, so emit a record */
554  arrayelems[narrayelems++] = Int32GetDatum(instance->leaderPid);
555  }
556  }
557 
558  /* Assert we didn't overrun arrayelems[] */
559  Assert(narrayelems <= lockData->nlocks);
560 
561  PG_RETURN_ARRAYTYPE_P(construct_array_builtin(arrayelems, narrayelems, INT4OID));
562 }
563 
564 
565 /*
566  * pg_safe_snapshot_blocking_pids - produce an array of the PIDs blocking
567  * given PID from getting a safe snapshot
568  *
569  * XXX this does not consider parallel-query cases; not clear how big a
570  * problem that is in practice
571  */
572 Datum
574 {
575  int blocked_pid = PG_GETARG_INT32(0);
576  int *blockers;
577  int num_blockers;
578  Datum *blocker_datums;
579 
580  /* A buffer big enough for any possible blocker list without truncation */
581  blockers = (int *) palloc(MaxBackends * sizeof(int));
582 
583  /* Collect a snapshot of processes waited for by GetSafeSnapshot */
584  num_blockers =
585  GetSafeSnapshotBlockingPids(blocked_pid, blockers, MaxBackends);
586 
587  /* Convert int array to Datum array */
588  if (num_blockers > 0)
589  {
590  int i;
591 
592  blocker_datums = (Datum *) palloc(num_blockers * sizeof(Datum));
593  for (i = 0; i < num_blockers; ++i)
594  blocker_datums[i] = Int32GetDatum(blockers[i]);
595  }
596  else
597  blocker_datums = NULL;
598 
599  PG_RETURN_ARRAYTYPE_P(construct_array_builtin(blocker_datums, num_blockers, INT4OID));
600 }
601 
602 
603 /*
604  * Functions for manipulating advisory locks
605  *
606  * We make use of the locktag fields as follows:
607  *
608  * field1: MyDatabaseId ... ensures locks are local to each database
609  * field2: first of 2 int4 keys, or high-order half of an int8 key
610  * field3: second of 2 int4 keys, or low-order half of an int8 key
611  * field4: 1 if using an int8 key, 2 if using 2 int4 keys
612  */
613 #define SET_LOCKTAG_INT64(tag, key64) \
614  SET_LOCKTAG_ADVISORY(tag, \
615  MyDatabaseId, \
616  (uint32) ((key64) >> 32), \
617  (uint32) (key64), \
618  1)
619 #define SET_LOCKTAG_INT32(tag, key1, key2) \
620  SET_LOCKTAG_ADVISORY(tag, MyDatabaseId, key1, key2, 2)
621 
622 /*
623  * pg_advisory_lock(int8) - acquire exclusive lock on an int8 key
624  */
625 Datum
627 {
628  int64 key = PG_GETARG_INT64(0);
629  LOCKTAG tag;
630 
631  SET_LOCKTAG_INT64(tag, key);
632 
633  (void) LockAcquire(&tag, ExclusiveLock, true, false);
634 
635  PG_RETURN_VOID();
636 }
637 
638 /*
639  * pg_advisory_xact_lock(int8) - acquire xact scoped
640  * exclusive lock on an int8 key
641  */
642 Datum
644 {
645  int64 key = PG_GETARG_INT64(0);
646  LOCKTAG tag;
647 
648  SET_LOCKTAG_INT64(tag, key);
649 
650  (void) LockAcquire(&tag, ExclusiveLock, false, false);
651 
652  PG_RETURN_VOID();
653 }
654 
655 /*
656  * pg_advisory_lock_shared(int8) - acquire share lock on an int8 key
657  */
658 Datum
660 {
661  int64 key = PG_GETARG_INT64(0);
662  LOCKTAG tag;
663 
664  SET_LOCKTAG_INT64(tag, key);
665 
666  (void) LockAcquire(&tag, ShareLock, true, false);
667 
668  PG_RETURN_VOID();
669 }
670 
671 /*
672  * pg_advisory_xact_lock_shared(int8) - acquire xact scoped
673  * share lock on an int8 key
674  */
675 Datum
677 {
678  int64 key = PG_GETARG_INT64(0);
679  LOCKTAG tag;
680 
681  SET_LOCKTAG_INT64(tag, key);
682 
683  (void) LockAcquire(&tag, ShareLock, false, false);
684 
685  PG_RETURN_VOID();
686 }
687 
688 /*
689  * pg_try_advisory_lock(int8) - acquire exclusive lock on an int8 key, no wait
690  *
691  * Returns true if successful, false if lock not available
692  */
693 Datum
695 {
696  int64 key = PG_GETARG_INT64(0);
697  LOCKTAG tag;
699 
700  SET_LOCKTAG_INT64(tag, key);
701 
702  res = LockAcquire(&tag, ExclusiveLock, true, true);
703 
705 }
706 
707 /*
708  * pg_try_advisory_xact_lock(int8) - acquire xact scoped
709  * exclusive lock on an int8 key, no wait
710  *
711  * Returns true if successful, false if lock not available
712  */
713 Datum
715 {
716  int64 key = PG_GETARG_INT64(0);
717  LOCKTAG tag;
719 
720  SET_LOCKTAG_INT64(tag, key);
721 
722  res = LockAcquire(&tag, ExclusiveLock, false, true);
723 
725 }
726 
727 /*
728  * pg_try_advisory_lock_shared(int8) - acquire share lock on an int8 key, no wait
729  *
730  * Returns true if successful, false if lock not available
731  */
732 Datum
734 {
735  int64 key = PG_GETARG_INT64(0);
736  LOCKTAG tag;
738 
739  SET_LOCKTAG_INT64(tag, key);
740 
741  res = LockAcquire(&tag, ShareLock, true, true);
742 
744 }
745 
746 /*
747  * pg_try_advisory_xact_lock_shared(int8) - acquire xact scoped
748  * share lock on an int8 key, no wait
749  *
750  * Returns true if successful, false if lock not available
751  */
752 Datum
754 {
755  int64 key = PG_GETARG_INT64(0);
756  LOCKTAG tag;
758 
759  SET_LOCKTAG_INT64(tag, key);
760 
761  res = LockAcquire(&tag, ShareLock, false, true);
762 
764 }
765 
766 /*
767  * pg_advisory_unlock(int8) - release exclusive lock on an int8 key
768  *
769  * Returns true if successful, false if lock was not held
770 */
771 Datum
773 {
774  int64 key = PG_GETARG_INT64(0);
775  LOCKTAG tag;
776  bool res;
777 
778  SET_LOCKTAG_INT64(tag, key);
779 
780  res = LockRelease(&tag, ExclusiveLock, true);
781 
783 }
784 
785 /*
786  * pg_advisory_unlock_shared(int8) - release share lock on an int8 key
787  *
788  * Returns true if successful, false if lock was not held
789  */
790 Datum
792 {
793  int64 key = PG_GETARG_INT64(0);
794  LOCKTAG tag;
795  bool res;
796 
797  SET_LOCKTAG_INT64(tag, key);
798 
799  res = LockRelease(&tag, ShareLock, true);
800 
802 }
803 
804 /*
805  * pg_advisory_lock(int4, int4) - acquire exclusive lock on 2 int4 keys
806  */
807 Datum
809 {
810  int32 key1 = PG_GETARG_INT32(0);
811  int32 key2 = PG_GETARG_INT32(1);
812  LOCKTAG tag;
813 
814  SET_LOCKTAG_INT32(tag, key1, key2);
815 
816  (void) LockAcquire(&tag, ExclusiveLock, true, false);
817 
818  PG_RETURN_VOID();
819 }
820 
821 /*
822  * pg_advisory_xact_lock(int4, int4) - acquire xact scoped
823  * exclusive lock on 2 int4 keys
824  */
825 Datum
827 {
828  int32 key1 = PG_GETARG_INT32(0);
829  int32 key2 = PG_GETARG_INT32(1);
830  LOCKTAG tag;
831 
832  SET_LOCKTAG_INT32(tag, key1, key2);
833 
834  (void) LockAcquire(&tag, ExclusiveLock, false, false);
835 
836  PG_RETURN_VOID();
837 }
838 
839 /*
840  * pg_advisory_lock_shared(int4, int4) - acquire share lock on 2 int4 keys
841  */
842 Datum
844 {
845  int32 key1 = PG_GETARG_INT32(0);
846  int32 key2 = PG_GETARG_INT32(1);
847  LOCKTAG tag;
848 
849  SET_LOCKTAG_INT32(tag, key1, key2);
850 
851  (void) LockAcquire(&tag, ShareLock, true, false);
852 
853  PG_RETURN_VOID();
854 }
855 
856 /*
857  * pg_advisory_xact_lock_shared(int4, int4) - acquire xact scoped
858  * share lock on 2 int4 keys
859  */
860 Datum
862 {
863  int32 key1 = PG_GETARG_INT32(0);
864  int32 key2 = PG_GETARG_INT32(1);
865  LOCKTAG tag;
866 
867  SET_LOCKTAG_INT32(tag, key1, key2);
868 
869  (void) LockAcquire(&tag, ShareLock, false, false);
870 
871  PG_RETURN_VOID();
872 }
873 
874 /*
875  * pg_try_advisory_lock(int4, int4) - acquire exclusive lock on 2 int4 keys, no wait
876  *
877  * Returns true if successful, false if lock not available
878  */
879 Datum
881 {
882  int32 key1 = PG_GETARG_INT32(0);
883  int32 key2 = PG_GETARG_INT32(1);
884  LOCKTAG tag;
886 
887  SET_LOCKTAG_INT32(tag, key1, key2);
888 
889  res = LockAcquire(&tag, ExclusiveLock, true, true);
890 
892 }
893 
894 /*
895  * pg_try_advisory_xact_lock(int4, int4) - acquire xact scoped
896  * exclusive lock on 2 int4 keys, no wait
897  *
898  * Returns true if successful, false if lock not available
899  */
900 Datum
902 {
903  int32 key1 = PG_GETARG_INT32(0);
904  int32 key2 = PG_GETARG_INT32(1);
905  LOCKTAG tag;
907 
908  SET_LOCKTAG_INT32(tag, key1, key2);
909 
910  res = LockAcquire(&tag, ExclusiveLock, false, true);
911 
913 }
914 
915 /*
916  * pg_try_advisory_lock_shared(int4, int4) - acquire share lock on 2 int4 keys, no wait
917  *
918  * Returns true if successful, false if lock not available
919  */
920 Datum
922 {
923  int32 key1 = PG_GETARG_INT32(0);
924  int32 key2 = PG_GETARG_INT32(1);
925  LOCKTAG tag;
927 
928  SET_LOCKTAG_INT32(tag, key1, key2);
929 
930  res = LockAcquire(&tag, ShareLock, true, true);
931 
933 }
934 
935 /*
936  * pg_try_advisory_xact_lock_shared(int4, int4) - acquire xact scoped
937  * share lock on 2 int4 keys, no wait
938  *
939  * Returns true if successful, false if lock not available
940  */
941 Datum
943 {
944  int32 key1 = PG_GETARG_INT32(0);
945  int32 key2 = PG_GETARG_INT32(1);
946  LOCKTAG tag;
948 
949  SET_LOCKTAG_INT32(tag, key1, key2);
950 
951  res = LockAcquire(&tag, ShareLock, false, true);
952 
954 }
955 
956 /*
957  * pg_advisory_unlock(int4, int4) - release exclusive lock on 2 int4 keys
958  *
959  * Returns true if successful, false if lock was not held
960 */
961 Datum
963 {
964  int32 key1 = PG_GETARG_INT32(0);
965  int32 key2 = PG_GETARG_INT32(1);
966  LOCKTAG tag;
967  bool res;
968 
969  SET_LOCKTAG_INT32(tag, key1, key2);
970 
971  res = LockRelease(&tag, ExclusiveLock, true);
972 
974 }
975 
976 /*
977  * pg_advisory_unlock_shared(int4, int4) - release share lock on 2 int4 keys
978  *
979  * Returns true if successful, false if lock was not held
980  */
981 Datum
983 {
984  int32 key1 = PG_GETARG_INT32(0);
985  int32 key2 = PG_GETARG_INT32(1);
986  LOCKTAG tag;
987  bool res;
988 
989  SET_LOCKTAG_INT32(tag, key1, key2);
990 
991  res = LockRelease(&tag, ShareLock, true);
992 
994 }
995 
996 /*
997  * pg_advisory_unlock_all() - release all advisory locks
998  */
999 Datum
1001 {
1003 
1004  PG_RETURN_VOID();
1005 }
#define PG_RETURN_ARRAYTYPE_P(x)
Definition: array.h:265
ArrayType * construct_array_builtin(Datum *elems, int nelems, Oid elmtype)
Definition: arrayfuncs.c:3374
int16 AttrNumber
Definition: attnum.h:21
static Datum values[MAXATTR]
Definition: bootstrap.c:152
#define CStringGetTextDatum(s)
Definition: builtins.h:97
signed int int32
Definition: c.h:494
#define Assert(condition)
Definition: c.h:858
#define lengthof(array)
Definition: c.h:788
uint32 LocalTransactionId
Definition: c.h:654
TupleDesc BlessTupleDesc(TupleDesc tupdesc)
Definition: execTuples.c:2158
#define PG_RETURN_VOID()
Definition: fmgr.h:349
#define PG_GETARG_INT64(n)
Definition: fmgr.h:283
#define PG_GETARG_INT32(n)
Definition: fmgr.h:269
#define PG_FUNCTION_ARGS
Definition: fmgr.h:193
#define PG_RETURN_BOOL(x)
Definition: fmgr.h:359
#define SRF_IS_FIRSTCALL()
Definition: funcapi.h:304
#define SRF_PERCALL_SETUP()
Definition: funcapi.h:308
#define SRF_RETURN_NEXT(_funcctx, _result)
Definition: funcapi.h:310
#define SRF_FIRSTCALL_INIT()
Definition: funcapi.h:306
static Datum HeapTupleGetDatum(const HeapTupleData *tuple)
Definition: funcapi.h:230
#define SRF_RETURN_DONE(_funcctx)
Definition: funcapi.h:328
int MaxBackends
Definition: globals.c:144
HeapTuple heap_form_tuple(TupleDesc tupleDescriptor, const Datum *values, const bool *isnull)
Definition: heaptuple.c:1116
int j
Definition: isn.c:74
int i
Definition: isn.c:73
LockAcquireResult LockAcquire(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock, bool dontWait)
Definition: lock.c:756
bool LockRelease(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
Definition: lock.c:1964
BlockedProcsData * GetBlockerStatusData(int blocked_pid)
Definition: lock.c:3803
LockData * GetLockStatusData(void)
Definition: lock.c:3611
void LockReleaseSession(LOCKMETHODID lockmethodid)
Definition: lock.c:2434
const char * GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode)
Definition: lock.c:4060
LockMethod GetLockTagsMethodTable(const LOCKTAG *locktag)
Definition: lock.c:486
LockTagType
Definition: lock.h:136
@ LOCKTAG_OBJECT
Definition: lock.h:145
@ LOCKTAG_RELATION_EXTEND
Definition: lock.h:138
@ LOCKTAG_RELATION
Definition: lock.h:137
@ LOCKTAG_TUPLE
Definition: lock.h:141
@ LOCKTAG_SPECULATIVE_TOKEN
Definition: lock.h:144
@ LOCKTAG_APPLY_TRANSACTION
Definition: lock.h:148
@ LOCKTAG_USERLOCK
Definition: lock.h:146
@ LOCKTAG_DATABASE_FROZEN_IDS
Definition: lock.h:139
@ LOCKTAG_VIRTUALTRANSACTION
Definition: lock.h:143
@ LOCKTAG_TRANSACTION
Definition: lock.h:142
@ LOCKTAG_PAGE
Definition: lock.h:140
@ LOCKTAG_ADVISORY
Definition: lock.h:147
#define USER_LOCKMETHOD
Definition: lock.h:126
#define LOCKBIT_OFF(lockmode)
Definition: lock.h:85
#define LOCKTAG_LAST_TYPE
Definition: lock.h:152
#define MAX_LOCKMODES
Definition: lock.h:82
#define LOCKBIT_ON(lockmode)
Definition: lock.h:84
LockAcquireResult
Definition: lock.h:500
@ LOCKACQUIRE_NOT_AVAIL
Definition: lock.h:501
int LOCKMODE
Definition: lockdefs.h:26
#define NoLock
Definition: lockdefs.h:34
#define ExclusiveLock
Definition: lockdefs.h:42
#define ShareLock
Definition: lockdefs.h:40
Datum pg_advisory_lock_int4(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:808
#define SET_LOCKTAG_INT64(tag, key64)
Definition: lockfuncs.c:613
Datum pg_try_advisory_xact_lock_int4(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:901
Datum pg_advisory_unlock_int8(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:772
Datum pg_advisory_lock_shared_int4(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:843
Datum pg_safe_snapshot_blocking_pids(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:573
Datum pg_advisory_lock_int8(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:626
Datum pg_try_advisory_xact_lock_shared_int8(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:753
Datum pg_advisory_xact_lock_int8(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:643
Datum pg_try_advisory_lock_shared_int4(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:921
static Datum VXIDGetDatum(ProcNumber procNumber, LocalTransactionId lxid)
Definition: lockfuncs.c:74
Datum pg_try_advisory_lock_int4(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:880
#define SET_LOCKTAG_INT32(tag, key1, key2)
Definition: lockfuncs.c:619
#define NUM_LOCK_STATUS_COLUMNS
Definition: lockfuncs.c:66
Datum pg_advisory_unlock_shared_int4(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:982
Datum pg_advisory_unlock_int4(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:962
static const char *const PredicateLockTagTypeNames[]
Definition: lockfuncs.c:47
Datum pg_try_advisory_lock_shared_int8(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:733
Datum pg_lock_status(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:93
Datum pg_advisory_xact_lock_int4(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:826
StaticAssertDecl(lengthof(LockTagTypeNames)==(LOCKTAG_LAST_TYPE+1), "array length mismatch")
Datum pg_try_advisory_xact_lock_int8(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:714
Datum pg_blocking_pids(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:466
Datum pg_advisory_lock_shared_int8(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:659
Datum pg_try_advisory_xact_lock_shared_int4(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:942
Datum pg_advisory_xact_lock_shared_int8(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:676
Datum pg_advisory_unlock_shared_int8(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:791
Datum pg_try_advisory_lock_int8(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:694
Datum pg_advisory_unlock_all(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:1000
const char *const LockTagTypeNames[]
Definition: lockfuncs.c:28
Datum pg_advisory_xact_lock_shared_int4(PG_FUNCTION_ARGS)
Definition: lockfuncs.c:861
void * palloc(Size size)
Definition: mcxt.c:1317
static PgChecksumMode mode
Definition: pg_checksums.c:56
while(p+4<=pend)
#define snprintf
Definition: port.h:238
static Datum TransactionIdGetDatum(TransactionId X)
Definition: postgres.h:272
uintptr_t Datum
Definition: postgres.h:64
static Datum Int16GetDatum(int16 X)
Definition: postgres.h:172
static Datum UInt16GetDatum(uint16 X)
Definition: postgres.h:192
static Datum BoolGetDatum(bool X)
Definition: postgres.h:102
static Datum ObjectIdGetDatum(Oid X)
Definition: postgres.h:252
static Datum Int32GetDatum(int32 X)
Definition: postgres.h:212
static Datum UInt32GetDatum(uint32 X)
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PredicateLockData * GetPredicateLockStatusData(void)
Definition: predicate.c:1430
int GetSafeSnapshotBlockingPids(int blocked_pid, int *output, int output_size)
Definition: predicate.c:1613
PredicateLockTargetType
@ PREDLOCKTAG_PAGE
@ PREDLOCKTAG_TUPLE
#define GET_PREDICATELOCKTARGETTAG_DB(locktag)
#define GET_PREDICATELOCKTARGETTAG_RELATION(locktag)
#define GET_PREDICATELOCKTARGETTAG_TYPE(locktag)
#define GET_PREDICATELOCKTARGETTAG_PAGE(locktag)
#define GET_PREDICATELOCKTARGETTAG_OFFSET(locktag)
int ProcNumber
Definition: procnumber.h:24
MemoryContextSwitchTo(old_ctx)
int first_lock
Definition: lock.h:476
int first_waiter
Definition: lock.h:480
int num_waiters
Definition: lock.h:481
int num_locks
Definition: lock.h:477
LockInstanceData * locks
Definition: lock.h:487
int * waiter_pids
Definition: lock.h:488
BlockedProcData * procs
Definition: lock.h:486
void * user_fctx
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MemoryContext multi_call_memory_ctx
Definition: funcapi.h:101
TupleDesc tuple_desc
Definition: funcapi.h:112
Definition: lock.h:165
uint8 locktag_type
Definition: lock.h:170
uint32 locktag_field3
Definition: lock.h:168
uint32 locktag_field1
Definition: lock.h:166
uint8 locktag_lockmethodid
Definition: lock.h:171
uint16 locktag_field4
Definition: lock.h:169
uint32 locktag_field2
Definition: lock.h:167
Definition: lock.h:466
LockInstanceData * locks
Definition: lock.h:468
int nelements
Definition: lock.h:467
LOCKMASK holdMask
Definition: lock.h:455
LOCKMODE waitLockMode
Definition: lock.h:456
bool fastpath
Definition: lock.h:462
LOCKTAG locktag
Definition: lock.h:454
TimestampTz waitStart
Definition: lock.h:458
int leaderPid
Definition: lock.h:461
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Definition: lock.h:457
const LOCKMASK * conflictTab
Definition: lock.h:111
PredicateLockData * predLockData
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LockData * lockData
Definition: lockfuncs.c:59
PREDICATELOCKTARGETTAG * locktags
SERIALIZABLEXACT * xacts
VirtualTransactionId vxid
LocalTransactionId localTransactionId
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ProcNumber procNumber
Definition: lock.h:61
TupleDesc CreateTemplateTupleDesc(int natts)
Definition: tupdesc.c:67
void TupleDescInitEntry(TupleDesc desc, AttrNumber attributeNumber, const char *attributeName, Oid oidtypeid, int32 typmod, int attdim)
Definition: tupdesc.c:651
static Datum TimestampTzGetDatum(TimestampTz X)
Definition: timestamp.h:52