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twophase.c
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1 /*-------------------------------------------------------------------------
2  *
3  * twophase.c
4  * Two-phase commit support functions.
5  *
6  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  * IDENTIFICATION
10  * src/backend/access/transam/twophase.c
11  *
12  * NOTES
13  * Each global transaction is associated with a global transaction
14  * identifier (GID). The client assigns a GID to a postgres
15  * transaction with the PREPARE TRANSACTION command.
16  *
17  * We keep all active global transactions in a shared memory array.
18  * When the PREPARE TRANSACTION command is issued, the GID is
19  * reserved for the transaction in the array. This is done before
20  * a WAL entry is made, because the reservation checks for duplicate
21  * GIDs and aborts the transaction if there already is a global
22  * transaction in prepared state with the same GID.
23  *
24  * A global transaction (gxact) also has dummy PGPROC; this is what keeps
25  * the XID considered running by TransactionIdIsInProgress. It is also
26  * convenient as a PGPROC to hook the gxact's locks to.
27  *
28  * Information to recover prepared transactions in case of crash is
29  * now stored in WAL for the common case. In some cases there will be
30  * an extended period between preparing a GXACT and commit/abort, in
31  * which case we need to separately record prepared transaction data
32  * in permanent storage. This includes locking information, pending
33  * notifications etc. All that state information is written to the
34  * per-transaction state file in the pg_twophase directory.
35  * All prepared transactions will be written prior to shutdown.
36  *
37  * Life track of state data is following:
38  *
39  * * On PREPARE TRANSACTION backend writes state data only to the WAL and
40  * stores pointer to the start of the WAL record in
41  * gxact->prepare_start_lsn.
42  * * If COMMIT occurs before checkpoint then backend reads data from WAL
43  * using prepare_start_lsn.
44  * * On checkpoint state data copied to files in pg_twophase directory and
45  * fsynced
46  * * If COMMIT happens after checkpoint then backend reads state data from
47  * files
48  *
49  * During replay and replication, TwoPhaseState also holds information
50  * about active prepared transactions that haven't been moved to disk yet.
51  *
52  * Replay of twophase records happens by the following rules:
53  *
54  * * At the beginning of recovery, pg_twophase is scanned once, filling
55  * TwoPhaseState with entries marked with gxact->inredo and
56  * gxact->ondisk. Two-phase file data older than the XID horizon of
57  * the redo position are discarded.
58  * * On PREPARE redo, the transaction is added to TwoPhaseState->prepXacts.
59  * gxact->inredo is set to true for such entries.
60  * * On Checkpoint we iterate through TwoPhaseState->prepXacts entries
61  * that have gxact->inredo set and are behind the redo_horizon. We
62  * save them to disk and then switch gxact->ondisk to true.
63  * * On COMMIT/ABORT we delete the entry from TwoPhaseState->prepXacts.
64  * If gxact->ondisk is true, the corresponding entry from the disk
65  * is additionally deleted.
66  * * RecoverPreparedTransactions(), StandbyRecoverPreparedTransactions()
67  * and PrescanPreparedTransactions() have been modified to go through
68  * gxact->inredo entries that have not made it to disk.
69  *
70  *-------------------------------------------------------------------------
71  */
72 #include "postgres.h"
73 
74 #include <fcntl.h>
75 #include <sys/stat.h>
76 #include <time.h>
77 #include <unistd.h>
78 
79 #include "access/commit_ts.h"
80 #include "access/htup_details.h"
81 #include "access/subtrans.h"
82 #include "access/transam.h"
83 #include "access/twophase.h"
84 #include "access/twophase_rmgr.h"
85 #include "access/xact.h"
86 #include "access/xlog.h"
87 #include "access/xloginsert.h"
88 #include "access/xlogreader.h"
89 #include "access/xlogutils.h"
90 #include "catalog/pg_type.h"
91 #include "catalog/storage.h"
92 #include "funcapi.h"
93 #include "miscadmin.h"
94 #include "pg_trace.h"
95 #include "pgstat.h"
96 #include "replication/origin.h"
97 #include "replication/syncrep.h"
98 #include "replication/walsender.h"
99 #include "storage/fd.h"
100 #include "storage/ipc.h"
101 #include "storage/md.h"
102 #include "storage/predicate.h"
103 #include "storage/proc.h"
104 #include "storage/procarray.h"
105 #include "storage/sinvaladt.h"
106 #include "storage/smgr.h"
107 #include "utils/builtins.h"
108 #include "utils/memutils.h"
109 #include "utils/timestamp.h"
110 
111 /*
112  * Directory where Two-phase commit files reside within PGDATA
113  */
114 #define TWOPHASE_DIR "pg_twophase"
115 
116 /* GUC variable, can't be changed after startup */
118 
119 /*
120  * This struct describes one global transaction that is in prepared state
121  * or attempting to become prepared.
122  *
123  * The lifecycle of a global transaction is:
124  *
125  * 1. After checking that the requested GID is not in use, set up an entry in
126  * the TwoPhaseState->prepXacts array with the correct GID and valid = false,
127  * and mark it as locked by my backend.
128  *
129  * 2. After successfully completing prepare, set valid = true and enter the
130  * referenced PGPROC into the global ProcArray.
131  *
132  * 3. To begin COMMIT PREPARED or ROLLBACK PREPARED, check that the entry is
133  * valid and not locked, then mark the entry as locked by storing my current
134  * backend ID into locking_backend. This prevents concurrent attempts to
135  * commit or rollback the same prepared xact.
136  *
137  * 4. On completion of COMMIT PREPARED or ROLLBACK PREPARED, remove the entry
138  * from the ProcArray and the TwoPhaseState->prepXacts array and return it to
139  * the freelist.
140  *
141  * Note that if the preparing transaction fails between steps 1 and 2, the
142  * entry must be removed so that the GID and the GlobalTransaction struct
143  * can be reused. See AtAbort_Twophase().
144  *
145  * typedef struct GlobalTransactionData *GlobalTransaction appears in
146  * twophase.h
147  */
148 
149 typedef struct GlobalTransactionData
150 {
151  GlobalTransaction next; /* list link for free list */
152  int pgprocno; /* ID of associated dummy PGPROC */
153  BackendId dummyBackendId; /* similar to backend id for backends */
154  TimestampTz prepared_at; /* time of preparation */
155 
156  /*
157  * Note that we need to keep track of two LSNs for each GXACT. We keep
158  * track of the start LSN because this is the address we must use to read
159  * state data back from WAL when committing a prepared GXACT. We keep
160  * track of the end LSN because that is the LSN we need to wait for prior
161  * to commit.
162  */
163  XLogRecPtr prepare_start_lsn; /* XLOG offset of prepare record start */
164  XLogRecPtr prepare_end_lsn; /* XLOG offset of prepare record end */
165  TransactionId xid; /* The GXACT id */
166 
167  Oid owner; /* ID of user that executed the xact */
168  BackendId locking_backend; /* backend currently working on the xact */
169  bool valid; /* true if PGPROC entry is in proc array */
170  bool ondisk; /* true if prepare state file is on disk */
171  bool inredo; /* true if entry was added via xlog_redo */
172  char gid[GIDSIZE]; /* The GID assigned to the prepared xact */
174 
175 /*
176  * Two Phase Commit shared state. Access to this struct is protected
177  * by TwoPhaseStateLock.
178  */
179 typedef struct TwoPhaseStateData
180 {
181  /* Head of linked list of free GlobalTransactionData structs */
183 
184  /* Number of valid prepXacts entries. */
186 
187  /* There are max_prepared_xacts items in this array */
190 
192 
193 /*
194  * Global transaction entry currently locked by us, if any. Note that any
195  * access to the entry pointed to by this variable must be protected by
196  * TwoPhaseStateLock, though obviously the pointer itself doesn't need to be
197  * (since it's just local memory).
198  */
200 
201 static bool twophaseExitRegistered = false;
202 
204  int nchildren,
205  TransactionId *children,
206  int nrels,
207  RelFileLocator *rels,
208  int nstats,
209  xl_xact_stats_item *stats,
210  int ninvalmsgs,
211  SharedInvalidationMessage *invalmsgs,
212  bool initfileinval,
213  const char *gid);
215  int nchildren,
216  TransactionId *children,
217  int nrels,
218  RelFileLocator *rels,
219  int nstats,
220  xl_xact_stats_item *stats,
221  const char *gid);
222 static void ProcessRecords(char *bufptr, TransactionId xid,
223  const TwoPhaseCallback callbacks[]);
224 static void RemoveGXact(GlobalTransaction gxact);
225 
226 static void XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len);
227 static char *ProcessTwoPhaseBuffer(TransactionId xid,
228  XLogRecPtr prepare_start_lsn,
229  bool fromdisk, bool setParent, bool setNextXid);
231  const char *gid, TimestampTz prepared_at, Oid owner,
232  Oid databaseid);
233 static void RemoveTwoPhaseFile(TransactionId xid, bool giveWarning);
234 static void RecreateTwoPhaseFile(TransactionId xid, void *content, int len);
235 
236 /*
237  * Initialization of shared memory
238  */
239 Size
241 {
242  Size size;
243 
244  /* Need the fixed struct, the array of pointers, and the GTD structs */
245  size = offsetof(TwoPhaseStateData, prepXacts);
246  size = add_size(size, mul_size(max_prepared_xacts,
247  sizeof(GlobalTransaction)));
248  size = MAXALIGN(size);
249  size = add_size(size, mul_size(max_prepared_xacts,
250  sizeof(GlobalTransactionData)));
251 
252  return size;
253 }
254 
255 void
257 {
258  bool found;
259 
260  TwoPhaseState = ShmemInitStruct("Prepared Transaction Table",
262  &found);
263  if (!IsUnderPostmaster)
264  {
265  GlobalTransaction gxacts;
266  int i;
267 
268  Assert(!found);
269  TwoPhaseState->freeGXacts = NULL;
271 
272  /*
273  * Initialize the linked list of free GlobalTransactionData structs
274  */
275  gxacts = (GlobalTransaction)
276  ((char *) TwoPhaseState +
277  MAXALIGN(offsetof(TwoPhaseStateData, prepXacts) +
279  for (i = 0; i < max_prepared_xacts; i++)
280  {
281  /* insert into linked list */
282  gxacts[i].next = TwoPhaseState->freeGXacts;
283  TwoPhaseState->freeGXacts = &gxacts[i];
284 
285  /* associate it with a PGPROC assigned by InitProcGlobal */
287 
288  /*
289  * Assign a unique ID for each dummy proc, so that the range of
290  * dummy backend IDs immediately follows the range of normal
291  * backend IDs. We don't dare to assign a real backend ID to dummy
292  * procs, because prepared transactions don't take part in cache
293  * invalidation like a real backend ID would imply, but having a
294  * unique ID for them is nevertheless handy. This arrangement
295  * allows you to allocate an array of size (MaxBackends +
296  * max_prepared_xacts + 1), and have a slot for every backend and
297  * prepared transaction. Currently multixact.c uses that
298  * technique.
299  */
300  gxacts[i].dummyBackendId = MaxBackends + 1 + i;
301  }
302  }
303  else
304  Assert(found);
305 }
306 
307 /*
308  * Exit hook to unlock the global transaction entry we're working on.
309  */
310 static void
312 {
313  /* same logic as abort */
315 }
316 
317 /*
318  * Abort hook to unlock the global transaction entry we're working on.
319  */
320 void
322 {
323  if (MyLockedGxact == NULL)
324  return;
325 
326  /*
327  * What to do with the locked global transaction entry? If we were in the
328  * process of preparing the transaction, but haven't written the WAL
329  * record and state file yet, the transaction must not be considered as
330  * prepared. Likewise, if we are in the process of finishing an
331  * already-prepared transaction, and fail after having already written the
332  * 2nd phase commit or rollback record to the WAL, the transaction should
333  * not be considered as prepared anymore. In those cases, just remove the
334  * entry from shared memory.
335  *
336  * Otherwise, the entry must be left in place so that the transaction can
337  * be finished later, so just unlock it.
338  *
339  * If we abort during prepare, after having written the WAL record, we
340  * might not have transferred all locks and other state to the prepared
341  * transaction yet. Likewise, if we abort during commit or rollback,
342  * after having written the WAL record, we might not have released all the
343  * resources held by the transaction yet. In those cases, the in-memory
344  * state can be wrong, but it's too late to back out.
345  */
346  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
347  if (!MyLockedGxact->valid)
349  else
351  LWLockRelease(TwoPhaseStateLock);
352 
353  MyLockedGxact = NULL;
354 }
355 
356 /*
357  * This is called after we have finished transferring state to the prepared
358  * PGPROC entry.
359  */
360 void
362 {
363  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
365  LWLockRelease(TwoPhaseStateLock);
366 
367  MyLockedGxact = NULL;
368 }
369 
370 
371 /*
372  * MarkAsPreparing
373  * Reserve the GID for the given transaction.
374  */
376 MarkAsPreparing(TransactionId xid, const char *gid,
377  TimestampTz prepared_at, Oid owner, Oid databaseid)
378 {
379  GlobalTransaction gxact;
380  int i;
381 
382  if (strlen(gid) >= GIDSIZE)
383  ereport(ERROR,
384  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
385  errmsg("transaction identifier \"%s\" is too long",
386  gid)));
387 
388  /* fail immediately if feature is disabled */
389  if (max_prepared_xacts == 0)
390  ereport(ERROR,
391  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
392  errmsg("prepared transactions are disabled"),
393  errhint("Set max_prepared_transactions to a nonzero value.")));
394 
395  /* on first call, register the exit hook */
397  {
399  twophaseExitRegistered = true;
400  }
401 
402  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
403 
404  /* Check for conflicting GID */
405  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
406  {
407  gxact = TwoPhaseState->prepXacts[i];
408  if (strcmp(gxact->gid, gid) == 0)
409  {
410  ereport(ERROR,
412  errmsg("transaction identifier \"%s\" is already in use",
413  gid)));
414  }
415  }
416 
417  /* Get a free gxact from the freelist */
418  if (TwoPhaseState->freeGXacts == NULL)
419  ereport(ERROR,
420  (errcode(ERRCODE_OUT_OF_MEMORY),
421  errmsg("maximum number of prepared transactions reached"),
422  errhint("Increase max_prepared_transactions (currently %d).",
424  gxact = TwoPhaseState->freeGXacts;
425  TwoPhaseState->freeGXacts = gxact->next;
426 
427  MarkAsPreparingGuts(gxact, xid, gid, prepared_at, owner, databaseid);
428 
429  gxact->ondisk = false;
430 
431  /* And insert it into the active array */
434 
435  LWLockRelease(TwoPhaseStateLock);
436 
437  return gxact;
438 }
439 
440 /*
441  * MarkAsPreparingGuts
442  *
443  * This uses a gxact struct and puts it into the active array.
444  * NOTE: this is also used when reloading a gxact after a crash; so avoid
445  * assuming that we can use very much backend context.
446  *
447  * Note: This function should be called with appropriate locks held.
448  */
449 static void
451  TimestampTz prepared_at, Oid owner, Oid databaseid)
452 {
453  PGPROC *proc;
454  int i;
455 
456  Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
457 
458  Assert(gxact != NULL);
459  proc = &ProcGlobal->allProcs[gxact->pgprocno];
460 
461  /* Initialize the PGPROC entry */
462  MemSet(proc, 0, sizeof(PGPROC));
463  proc->pgprocno = gxact->pgprocno;
464  SHMQueueElemInit(&(proc->links));
467  {
468  /* clone VXID, for TwoPhaseGetXidByVirtualXID() to find */
469  proc->lxid = MyProc->lxid;
470  proc->backendId = MyBackendId;
471  }
472  else
473  {
475  /* GetLockConflicts() uses this to specify a wait on the XID */
476  proc->lxid = xid;
477  proc->backendId = InvalidBackendId;
478  }
479  proc->xid = xid;
480  Assert(proc->xmin == InvalidTransactionId);
481  proc->delayChkptFlags = 0;
482  proc->statusFlags = 0;
483  proc->pid = 0;
484  proc->databaseId = databaseid;
485  proc->roleId = owner;
486  proc->tempNamespaceId = InvalidOid;
487  proc->isBackgroundWorker = false;
488  proc->lwWaiting = false;
489  proc->lwWaitMode = 0;
490  proc->waitLock = NULL;
491  proc->waitProcLock = NULL;
492  pg_atomic_init_u64(&proc->waitStart, 0);
493  for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
494  SHMQueueInit(&(proc->myProcLocks[i]));
495  /* subxid data must be filled later by GXactLoadSubxactData */
496  proc->subxidStatus.overflowed = false;
497  proc->subxidStatus.count = 0;
498 
499  gxact->prepared_at = prepared_at;
500  gxact->xid = xid;
501  gxact->owner = owner;
502  gxact->locking_backend = MyBackendId;
503  gxact->valid = false;
504  gxact->inredo = false;
505  strcpy(gxact->gid, gid);
506 
507  /*
508  * Remember that we have this GlobalTransaction entry locked for us. If we
509  * abort after this, we must release it.
510  */
511  MyLockedGxact = gxact;
512 }
513 
514 /*
515  * GXactLoadSubxactData
516  *
517  * If the transaction being persisted had any subtransactions, this must
518  * be called before MarkAsPrepared() to load information into the dummy
519  * PGPROC.
520  */
521 static void
523  TransactionId *children)
524 {
525  PGPROC *proc = &ProcGlobal->allProcs[gxact->pgprocno];
526 
527  /* We need no extra lock since the GXACT isn't valid yet */
528  if (nsubxacts > PGPROC_MAX_CACHED_SUBXIDS)
529  {
530  proc->subxidStatus.overflowed = true;
531  nsubxacts = PGPROC_MAX_CACHED_SUBXIDS;
532  }
533  if (nsubxacts > 0)
534  {
535  memcpy(proc->subxids.xids, children,
536  nsubxacts * sizeof(TransactionId));
537  proc->subxidStatus.count = nsubxacts;
538  }
539 }
540 
541 /*
542  * MarkAsPrepared
543  * Mark the GXACT as fully valid, and enter it into the global ProcArray.
544  *
545  * lock_held indicates whether caller already holds TwoPhaseStateLock.
546  */
547 static void
548 MarkAsPrepared(GlobalTransaction gxact, bool lock_held)
549 {
550  /* Lock here may be overkill, but I'm not convinced of that ... */
551  if (!lock_held)
552  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
553  Assert(!gxact->valid);
554  gxact->valid = true;
555  if (!lock_held)
556  LWLockRelease(TwoPhaseStateLock);
557 
558  /*
559  * Put it into the global ProcArray so TransactionIdIsInProgress considers
560  * the XID as still running.
561  */
563 }
564 
565 /*
566  * LockGXact
567  * Locate the prepared transaction and mark it busy for COMMIT or PREPARE.
568  */
569 static GlobalTransaction
570 LockGXact(const char *gid, Oid user)
571 {
572  int i;
573 
574  /* on first call, register the exit hook */
576  {
578  twophaseExitRegistered = true;
579  }
580 
581  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
582 
583  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
584  {
586  PGPROC *proc = &ProcGlobal->allProcs[gxact->pgprocno];
587 
588  /* Ignore not-yet-valid GIDs */
589  if (!gxact->valid)
590  continue;
591  if (strcmp(gxact->gid, gid) != 0)
592  continue;
593 
594  /* Found it, but has someone else got it locked? */
595  if (gxact->locking_backend != InvalidBackendId)
596  ereport(ERROR,
597  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
598  errmsg("prepared transaction with identifier \"%s\" is busy",
599  gid)));
600 
601  if (user != gxact->owner && !superuser_arg(user))
602  ereport(ERROR,
603  (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
604  errmsg("permission denied to finish prepared transaction"),
605  errhint("Must be superuser or the user that prepared the transaction.")));
606 
607  /*
608  * Note: it probably would be possible to allow committing from
609  * another database; but at the moment NOTIFY is known not to work and
610  * there may be some other issues as well. Hence disallow until
611  * someone gets motivated to make it work.
612  */
613  if (MyDatabaseId != proc->databaseId)
614  ereport(ERROR,
615  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
616  errmsg("prepared transaction belongs to another database"),
617  errhint("Connect to the database where the transaction was prepared to finish it.")));
618 
619  /* OK for me to lock it */
620  gxact->locking_backend = MyBackendId;
621  MyLockedGxact = gxact;
622 
623  LWLockRelease(TwoPhaseStateLock);
624 
625  return gxact;
626  }
627 
628  LWLockRelease(TwoPhaseStateLock);
629 
630  ereport(ERROR,
631  (errcode(ERRCODE_UNDEFINED_OBJECT),
632  errmsg("prepared transaction with identifier \"%s\" does not exist",
633  gid)));
634 
635  /* NOTREACHED */
636  return NULL;
637 }
638 
639 /*
640  * RemoveGXact
641  * Remove the prepared transaction from the shared memory array.
642  *
643  * NB: caller should have already removed it from ProcArray
644  */
645 static void
647 {
648  int i;
649 
650  Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
651 
652  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
653  {
654  if (gxact == TwoPhaseState->prepXacts[i])
655  {
656  /* remove from the active array */
659 
660  /* and put it back in the freelist */
661  gxact->next = TwoPhaseState->freeGXacts;
662  TwoPhaseState->freeGXacts = gxact;
663 
664  return;
665  }
666  }
667 
668  elog(ERROR, "failed to find %p in GlobalTransaction array", gxact);
669 }
670 
671 /*
672  * Returns an array of all prepared transactions for the user-level
673  * function pg_prepared_xact.
674  *
675  * The returned array and all its elements are copies of internal data
676  * structures, to minimize the time we need to hold the TwoPhaseStateLock.
677  *
678  * WARNING -- we return even those transactions that are not fully prepared
679  * yet. The caller should filter them out if he doesn't want them.
680  *
681  * The returned array is palloc'd.
682  */
683 static int
685 {
686  GlobalTransaction array;
687  int num;
688  int i;
689 
690  LWLockAcquire(TwoPhaseStateLock, LW_SHARED);
691 
692  if (TwoPhaseState->numPrepXacts == 0)
693  {
694  LWLockRelease(TwoPhaseStateLock);
695 
696  *gxacts = NULL;
697  return 0;
698  }
699 
701  array = (GlobalTransaction) palloc(sizeof(GlobalTransactionData) * num);
702  *gxacts = array;
703  for (i = 0; i < num; i++)
704  memcpy(array + i, TwoPhaseState->prepXacts[i],
705  sizeof(GlobalTransactionData));
706 
707  LWLockRelease(TwoPhaseStateLock);
708 
709  return num;
710 }
711 
712 
713 /* Working status for pg_prepared_xact */
714 typedef struct
715 {
717  int ngxacts;
718  int currIdx;
719 } Working_State;
720 
721 /*
722  * pg_prepared_xact
723  * Produce a view with one row per prepared transaction.
724  *
725  * This function is here so we don't have to export the
726  * GlobalTransactionData struct definition.
727  */
728 Datum
730 {
731  FuncCallContext *funcctx;
733 
734  if (SRF_IS_FIRSTCALL())
735  {
736  TupleDesc tupdesc;
737  MemoryContext oldcontext;
738 
739  /* create a function context for cross-call persistence */
740  funcctx = SRF_FIRSTCALL_INIT();
741 
742  /*
743  * Switch to memory context appropriate for multiple function calls
744  */
745  oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
746 
747  /* build tupdesc for result tuples */
748  /* this had better match pg_prepared_xacts view in system_views.sql */
749  tupdesc = CreateTemplateTupleDesc(5);
750  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "transaction",
751  XIDOID, -1, 0);
752  TupleDescInitEntry(tupdesc, (AttrNumber) 2, "gid",
753  TEXTOID, -1, 0);
754  TupleDescInitEntry(tupdesc, (AttrNumber) 3, "prepared",
755  TIMESTAMPTZOID, -1, 0);
756  TupleDescInitEntry(tupdesc, (AttrNumber) 4, "ownerid",
757  OIDOID, -1, 0);
758  TupleDescInitEntry(tupdesc, (AttrNumber) 5, "dbid",
759  OIDOID, -1, 0);
760 
761  funcctx->tuple_desc = BlessTupleDesc(tupdesc);
762 
763  /*
764  * Collect all the 2PC status information that we will format and send
765  * out as a result set.
766  */
767  status = (Working_State *) palloc(sizeof(Working_State));
768  funcctx->user_fctx = (void *) status;
769 
770  status->ngxacts = GetPreparedTransactionList(&status->array);
771  status->currIdx = 0;
772 
773  MemoryContextSwitchTo(oldcontext);
774  }
775 
776  funcctx = SRF_PERCALL_SETUP();
777  status = (Working_State *) funcctx->user_fctx;
778 
779  while (status->array != NULL && status->currIdx < status->ngxacts)
780  {
781  GlobalTransaction gxact = &status->array[status->currIdx++];
782  PGPROC *proc = &ProcGlobal->allProcs[gxact->pgprocno];
783  Datum values[5] = {0};
784  bool nulls[5] = {0};
785  HeapTuple tuple;
786  Datum result;
787 
788  if (!gxact->valid)
789  continue;
790 
791  /*
792  * Form tuple with appropriate data.
793  */
794 
795  values[0] = TransactionIdGetDatum(proc->xid);
796  values[1] = CStringGetTextDatum(gxact->gid);
798  values[3] = ObjectIdGetDatum(gxact->owner);
799  values[4] = ObjectIdGetDatum(proc->databaseId);
800 
801  tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
802  result = HeapTupleGetDatum(tuple);
803  SRF_RETURN_NEXT(funcctx, result);
804  }
805 
806  SRF_RETURN_DONE(funcctx);
807 }
808 
809 /*
810  * TwoPhaseGetGXact
811  * Get the GlobalTransaction struct for a prepared transaction
812  * specified by XID
813  *
814  * If lock_held is set to true, TwoPhaseStateLock will not be taken, so the
815  * caller had better hold it.
816  */
817 static GlobalTransaction
818 TwoPhaseGetGXact(TransactionId xid, bool lock_held)
819 {
820  GlobalTransaction result = NULL;
821  int i;
822 
823  static TransactionId cached_xid = InvalidTransactionId;
824  static GlobalTransaction cached_gxact = NULL;
825 
826  Assert(!lock_held || LWLockHeldByMe(TwoPhaseStateLock));
827 
828  /*
829  * During a recovery, COMMIT PREPARED, or ABORT PREPARED, we'll be called
830  * repeatedly for the same XID. We can save work with a simple cache.
831  */
832  if (xid == cached_xid)
833  return cached_gxact;
834 
835  if (!lock_held)
836  LWLockAcquire(TwoPhaseStateLock, LW_SHARED);
837 
838  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
839  {
841 
842  if (gxact->xid == xid)
843  {
844  result = gxact;
845  break;
846  }
847  }
848 
849  if (!lock_held)
850  LWLockRelease(TwoPhaseStateLock);
851 
852  if (result == NULL) /* should not happen */
853  elog(ERROR, "failed to find GlobalTransaction for xid %u", xid);
854 
855  cached_xid = xid;
856  cached_gxact = result;
857 
858  return result;
859 }
860 
861 /*
862  * TwoPhaseGetXidByVirtualXID
863  * Lookup VXID among xacts prepared since last startup.
864  *
865  * (This won't find recovered xacts.) If more than one matches, return any
866  * and set "have_more" to true. To witness multiple matches, a single
867  * BackendId must consume 2^32 LXIDs, with no intervening database restart.
868  */
871  bool *have_more)
872 {
873  int i;
875 
877  LWLockAcquire(TwoPhaseStateLock, LW_SHARED);
878 
879  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
880  {
882  PGPROC *proc;
883  VirtualTransactionId proc_vxid;
884 
885  if (!gxact->valid)
886  continue;
887  proc = &ProcGlobal->allProcs[gxact->pgprocno];
888  GET_VXID_FROM_PGPROC(proc_vxid, *proc);
889  if (VirtualTransactionIdEquals(vxid, proc_vxid))
890  {
891  /* Startup process sets proc->backendId to InvalidBackendId. */
892  Assert(!gxact->inredo);
893 
894  if (result != InvalidTransactionId)
895  {
896  *have_more = true;
897  break;
898  }
899  result = gxact->xid;
900  }
901  }
902 
903  LWLockRelease(TwoPhaseStateLock);
904 
905  return result;
906 }
907 
908 /*
909  * TwoPhaseGetDummyBackendId
910  * Get the dummy backend ID for prepared transaction specified by XID
911  *
912  * Dummy backend IDs are similar to real backend IDs of real backends.
913  * They start at MaxBackends + 1, and are unique across all currently active
914  * real backends and prepared transactions. If lock_held is set to true,
915  * TwoPhaseStateLock will not be taken, so the caller had better hold it.
916  */
917 BackendId
919 {
920  GlobalTransaction gxact = TwoPhaseGetGXact(xid, lock_held);
921 
922  return gxact->dummyBackendId;
923 }
924 
925 /*
926  * TwoPhaseGetDummyProc
927  * Get the PGPROC that represents a prepared transaction specified by XID
928  *
929  * If lock_held is set to true, TwoPhaseStateLock will not be taken, so the
930  * caller had better hold it.
931  */
932 PGPROC *
934 {
935  GlobalTransaction gxact = TwoPhaseGetGXact(xid, lock_held);
936 
937  return &ProcGlobal->allProcs[gxact->pgprocno];
938 }
939 
940 /************************************************************************/
941 /* State file support */
942 /************************************************************************/
943 
944 #define TwoPhaseFilePath(path, xid) \
945  snprintf(path, MAXPGPATH, TWOPHASE_DIR "/%08X", xid)
946 
947 /*
948  * 2PC state file format:
949  *
950  * 1. TwoPhaseFileHeader
951  * 2. TransactionId[] (subtransactions)
952  * 3. RelFileLocator[] (files to be deleted at commit)
953  * 4. RelFileLocator[] (files to be deleted at abort)
954  * 5. SharedInvalidationMessage[] (inval messages to be sent at commit)
955  * 6. TwoPhaseRecordOnDisk
956  * 7. ...
957  * 8. TwoPhaseRecordOnDisk (end sentinel, rmid == TWOPHASE_RM_END_ID)
958  * 9. checksum (CRC-32C)
959  *
960  * Each segment except the final checksum is MAXALIGN'd.
961  */
962 
963 /*
964  * Header for a 2PC state file
965  */
966 #define TWOPHASE_MAGIC 0x57F94534 /* format identifier */
967 
969 
970 /*
971  * Header for each record in a state file
972  *
973  * NOTE: len counts only the rmgr data, not the TwoPhaseRecordOnDisk header.
974  * The rmgr data will be stored starting on a MAXALIGN boundary.
975  */
976 typedef struct TwoPhaseRecordOnDisk
977 {
978  uint32 len; /* length of rmgr data */
979  TwoPhaseRmgrId rmid; /* resource manager for this record */
980  uint16 info; /* flag bits for use by rmgr */
982 
983 /*
984  * During prepare, the state file is assembled in memory before writing it
985  * to WAL and the actual state file. We use a chain of StateFileChunk blocks
986  * for that.
987  */
988 typedef struct StateFileChunk
989 {
990  char *data;
994 
995 static struct xllist
996 {
997  StateFileChunk *head; /* first data block in the chain */
998  StateFileChunk *tail; /* last block in chain */
1000  uint32 bytes_free; /* free bytes left in tail block */
1001  uint32 total_len; /* total data bytes in chain */
1003 
1004 
1005 /*
1006  * Append a block of data to records data structure.
1007  *
1008  * NB: each block is padded to a MAXALIGN multiple. This must be
1009  * accounted for when the file is later read!
1010  *
1011  * The data is copied, so the caller is free to modify it afterwards.
1012  */
1013 static void
1015 {
1016  uint32 padlen = MAXALIGN(len);
1017 
1018  if (padlen > records.bytes_free)
1019  {
1020  records.tail->next = palloc0(sizeof(StateFileChunk));
1022  records.tail->len = 0;
1023  records.tail->next = NULL;
1024  records.num_chunks++;
1025 
1026  records.bytes_free = Max(padlen, 512);
1028  }
1029 
1030  memcpy(((char *) records.tail->data) + records.tail->len, data, len);
1031  records.tail->len += padlen;
1032  records.bytes_free -= padlen;
1033  records.total_len += padlen;
1034 }
1035 
1036 /*
1037  * Start preparing a state file.
1038  *
1039  * Initializes data structure and inserts the 2PC file header record.
1040  */
1041 void
1043 {
1044  PGPROC *proc = &ProcGlobal->allProcs[gxact->pgprocno];
1045  TransactionId xid = gxact->xid;
1046  TwoPhaseFileHeader hdr;
1047  TransactionId *children;
1048  RelFileLocator *commitrels;
1049  RelFileLocator *abortrels;
1050  xl_xact_stats_item *abortstats = NULL;
1051  xl_xact_stats_item *commitstats = NULL;
1052  SharedInvalidationMessage *invalmsgs;
1053 
1054  /* Initialize linked list */
1055  records.head = palloc0(sizeof(StateFileChunk));
1056  records.head->len = 0;
1057  records.head->next = NULL;
1058 
1059  records.bytes_free = Max(sizeof(TwoPhaseFileHeader), 512);
1061 
1063  records.num_chunks = 1;
1064 
1065  records.total_len = 0;
1066 
1067  /* Create header */
1068  hdr.magic = TWOPHASE_MAGIC;
1069  hdr.total_len = 0; /* EndPrepare will fill this in */
1070  hdr.xid = xid;
1071  hdr.database = proc->databaseId;
1072  hdr.prepared_at = gxact->prepared_at;
1073  hdr.owner = gxact->owner;
1074  hdr.nsubxacts = xactGetCommittedChildren(&children);
1075  hdr.ncommitrels = smgrGetPendingDeletes(true, &commitrels);
1076  hdr.nabortrels = smgrGetPendingDeletes(false, &abortrels);
1077  hdr.ncommitstats =
1078  pgstat_get_transactional_drops(true, &commitstats);
1079  hdr.nabortstats =
1080  pgstat_get_transactional_drops(false, &abortstats);
1082  &hdr.initfileinval);
1083  hdr.gidlen = strlen(gxact->gid) + 1; /* Include '\0' */
1084  /* EndPrepare will fill the origin data, if necessary */
1086  hdr.origin_timestamp = 0;
1087 
1088  save_state_data(&hdr, sizeof(TwoPhaseFileHeader));
1089  save_state_data(gxact->gid, hdr.gidlen);
1090 
1091  /*
1092  * Add the additional info about subxacts, deletable files and cache
1093  * invalidation messages.
1094  */
1095  if (hdr.nsubxacts > 0)
1096  {
1097  save_state_data(children, hdr.nsubxacts * sizeof(TransactionId));
1098  /* While we have the child-xact data, stuff it in the gxact too */
1099  GXactLoadSubxactData(gxact, hdr.nsubxacts, children);
1100  }
1101  if (hdr.ncommitrels > 0)
1102  {
1103  save_state_data(commitrels, hdr.ncommitrels * sizeof(RelFileLocator));
1104  pfree(commitrels);
1105  }
1106  if (hdr.nabortrels > 0)
1107  {
1108  save_state_data(abortrels, hdr.nabortrels * sizeof(RelFileLocator));
1109  pfree(abortrels);
1110  }
1111  if (hdr.ncommitstats > 0)
1112  {
1113  save_state_data(commitstats,
1114  hdr.ncommitstats * sizeof(xl_xact_stats_item));
1115  pfree(commitstats);
1116  }
1117  if (hdr.nabortstats > 0)
1118  {
1119  save_state_data(abortstats,
1120  hdr.nabortstats * sizeof(xl_xact_stats_item));
1121  pfree(abortstats);
1122  }
1123  if (hdr.ninvalmsgs > 0)
1124  {
1125  save_state_data(invalmsgs,
1126  hdr.ninvalmsgs * sizeof(SharedInvalidationMessage));
1127  pfree(invalmsgs);
1128  }
1129 }
1130 
1131 /*
1132  * Finish preparing state data and writing it to WAL.
1133  */
1134 void
1136 {
1137  TwoPhaseFileHeader *hdr;
1138  StateFileChunk *record;
1139  bool replorigin;
1140 
1141  /* Add the end sentinel to the list of 2PC records */
1143  NULL, 0);
1144 
1145  /* Go back and fill in total_len in the file header record */
1146  hdr = (TwoPhaseFileHeader *) records.head->data;
1147  Assert(hdr->magic == TWOPHASE_MAGIC);
1148  hdr->total_len = records.total_len + sizeof(pg_crc32c);
1149 
1150  replorigin = (replorigin_session_origin != InvalidRepOriginId &&
1152 
1153  if (replorigin)
1154  {
1157  }
1158 
1159  /*
1160  * If the data size exceeds MaxAllocSize, we won't be able to read it in
1161  * ReadTwoPhaseFile. Check for that now, rather than fail in the case
1162  * where we write data to file and then re-read at commit time.
1163  */
1164  if (hdr->total_len > MaxAllocSize)
1165  ereport(ERROR,
1166  (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
1167  errmsg("two-phase state file maximum length exceeded")));
1168 
1169  /*
1170  * Now writing 2PC state data to WAL. We let the WAL's CRC protection
1171  * cover us, so no need to calculate a separate CRC.
1172  *
1173  * We have to set DELAY_CHKPT_START here, too; otherwise a checkpoint
1174  * starting immediately after the WAL record is inserted could complete
1175  * without fsync'ing our state file. (This is essentially the same kind
1176  * of race condition as the COMMIT-to-clog-write case that
1177  * RecordTransactionCommit uses DELAY_CHKPT_START for; see notes there.)
1178  *
1179  * We save the PREPARE record's location in the gxact for later use by
1180  * CheckPointTwoPhase.
1181  */
1183 
1185 
1188 
1189  XLogBeginInsert();
1190  for (record = records.head; record != NULL; record = record->next)
1191  XLogRegisterData(record->data, record->len);
1192 
1194 
1195  gxact->prepare_end_lsn = XLogInsert(RM_XACT_ID, XLOG_XACT_PREPARE);
1196 
1197  if (replorigin)
1198  {
1199  /* Move LSNs forward for this replication origin */
1201  gxact->prepare_end_lsn);
1202  }
1203 
1204  XLogFlush(gxact->prepare_end_lsn);
1205 
1206  /* If we crash now, we have prepared: WAL replay will fix things */
1207 
1208  /* Store record's start location to read that later on Commit */
1210 
1211  /*
1212  * Mark the prepared transaction as valid. As soon as xact.c marks MyProc
1213  * as not running our XID (which it will do immediately after this
1214  * function returns), others can commit/rollback the xact.
1215  *
1216  * NB: a side effect of this is to make a dummy ProcArray entry for the
1217  * prepared XID. This must happen before we clear the XID from MyProc /
1218  * ProcGlobal->xids[], else there is a window where the XID is not running
1219  * according to TransactionIdIsInProgress, and onlookers would be entitled
1220  * to assume the xact crashed. Instead we have a window where the same
1221  * XID appears twice in ProcArray, which is OK.
1222  */
1223  MarkAsPrepared(gxact, false);
1224 
1225  /*
1226  * Now we can mark ourselves as out of the commit critical section: a
1227  * checkpoint starting after this will certainly see the gxact as a
1228  * candidate for fsyncing.
1229  */
1231 
1232  /*
1233  * Remember that we have this GlobalTransaction entry locked for us. If
1234  * we crash after this point, it's too late to abort, but we must unlock
1235  * it so that the prepared transaction can be committed or rolled back.
1236  */
1237  MyLockedGxact = gxact;
1238 
1239  END_CRIT_SECTION();
1240 
1241  /*
1242  * Wait for synchronous replication, if required.
1243  *
1244  * Note that at this stage we have marked the prepare, but still show as
1245  * running in the procarray (twice!) and continue to hold locks.
1246  */
1247  SyncRepWaitForLSN(gxact->prepare_end_lsn, false);
1248 
1249  records.tail = records.head = NULL;
1250  records.num_chunks = 0;
1251 }
1252 
1253 /*
1254  * Register a 2PC record to be written to state file.
1255  */
1256 void
1258  const void *data, uint32 len)
1259 {
1260  TwoPhaseRecordOnDisk record;
1261 
1262  record.rmid = rmid;
1263  record.info = info;
1264  record.len = len;
1265  save_state_data(&record, sizeof(TwoPhaseRecordOnDisk));
1266  if (len > 0)
1268 }
1269 
1270 
1271 /*
1272  * Read and validate the state file for xid.
1273  *
1274  * If it looks OK (has a valid magic number and CRC), return the palloc'd
1275  * contents of the file, issuing an error when finding corrupted data. If
1276  * missing_ok is true, which indicates that missing files can be safely
1277  * ignored, then return NULL. This state can be reached when doing recovery.
1278  */
1279 static char *
1280 ReadTwoPhaseFile(TransactionId xid, bool missing_ok)
1281 {
1282  char path[MAXPGPATH];
1283  char *buf;
1284  TwoPhaseFileHeader *hdr;
1285  int fd;
1286  struct stat stat;
1287  uint32 crc_offset;
1288  pg_crc32c calc_crc,
1289  file_crc;
1290  int r;
1291 
1292  TwoPhaseFilePath(path, xid);
1293 
1294  fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
1295  if (fd < 0)
1296  {
1297  if (missing_ok && errno == ENOENT)
1298  return NULL;
1299 
1300  ereport(ERROR,
1302  errmsg("could not open file \"%s\": %m", path)));
1303  }
1304 
1305  /*
1306  * Check file length. We can determine a lower bound pretty easily. We
1307  * set an upper bound to avoid palloc() failure on a corrupt file, though
1308  * we can't guarantee that we won't get an out of memory error anyway,
1309  * even on a valid file.
1310  */
1311  if (fstat(fd, &stat))
1312  ereport(ERROR,
1314  errmsg("could not stat file \"%s\": %m", path)));
1315 
1316  if (stat.st_size < (MAXALIGN(sizeof(TwoPhaseFileHeader)) +
1317  MAXALIGN(sizeof(TwoPhaseRecordOnDisk)) +
1318  sizeof(pg_crc32c)) ||
1320  ereport(ERROR,
1322  errmsg_plural("incorrect size of file \"%s\": %lld byte",
1323  "incorrect size of file \"%s\": %lld bytes",
1324  (long long int) stat.st_size, path,
1325  (long long int) stat.st_size)));
1326 
1327  crc_offset = stat.st_size - sizeof(pg_crc32c);
1328  if (crc_offset != MAXALIGN(crc_offset))
1329  ereport(ERROR,
1331  errmsg("incorrect alignment of CRC offset for file \"%s\"",
1332  path)));
1333 
1334  /*
1335  * OK, slurp in the file.
1336  */
1337  buf = (char *) palloc(stat.st_size);
1338 
1340  r = read(fd, buf, stat.st_size);
1341  if (r != stat.st_size)
1342  {
1343  if (r < 0)
1344  ereport(ERROR,
1346  errmsg("could not read file \"%s\": %m", path)));
1347  else
1348  ereport(ERROR,
1349  (errmsg("could not read file \"%s\": read %d of %lld",
1350  path, r, (long long int) stat.st_size)));
1351  }
1352 
1354 
1355  if (CloseTransientFile(fd) != 0)
1356  ereport(ERROR,
1358  errmsg("could not close file \"%s\": %m", path)));
1359 
1360  hdr = (TwoPhaseFileHeader *) buf;
1361  if (hdr->magic != TWOPHASE_MAGIC)
1362  ereport(ERROR,
1364  errmsg("invalid magic number stored in file \"%s\"",
1365  path)));
1366 
1367  if (hdr->total_len != stat.st_size)
1368  ereport(ERROR,
1370  errmsg("invalid size stored in file \"%s\"",
1371  path)));
1372 
1373  INIT_CRC32C(calc_crc);
1374  COMP_CRC32C(calc_crc, buf, crc_offset);
1375  FIN_CRC32C(calc_crc);
1376 
1377  file_crc = *((pg_crc32c *) (buf + crc_offset));
1378 
1379  if (!EQ_CRC32C(calc_crc, file_crc))
1380  ereport(ERROR,
1382  errmsg("calculated CRC checksum does not match value stored in file \"%s\"",
1383  path)));
1384 
1385  return buf;
1386 }
1387 
1388 
1389 /*
1390  * Reads 2PC data from xlog. During checkpoint this data will be moved to
1391  * twophase files and ReadTwoPhaseFile should be used instead.
1392  *
1393  * Note clearly that this function can access WAL during normal operation,
1394  * similarly to the way WALSender or Logical Decoding would do.
1395  */
1396 static void
1398 {
1399  XLogRecord *record;
1401  char *errormsg;
1402 
1404  XL_ROUTINE(.page_read = &read_local_xlog_page,
1405  .segment_open = &wal_segment_open,
1406  .segment_close = &wal_segment_close),
1407  NULL);
1408  if (!xlogreader)
1409  ereport(ERROR,
1410  (errcode(ERRCODE_OUT_OF_MEMORY),
1411  errmsg("out of memory"),
1412  errdetail("Failed while allocating a WAL reading processor.")));
1413 
1414  XLogBeginRead(xlogreader, lsn);
1415  record = XLogReadRecord(xlogreader, &errormsg);
1416 
1417  if (record == NULL)
1418  {
1419  if (errormsg)
1420  ereport(ERROR,
1422  errmsg("could not read two-phase state from WAL at %X/%X: %s",
1423  LSN_FORMAT_ARGS(lsn), errormsg)));
1424  else
1425  ereport(ERROR,
1427  errmsg("could not read two-phase state from WAL at %X/%X",
1428  LSN_FORMAT_ARGS(lsn))));
1429  }
1430 
1431  if (XLogRecGetRmid(xlogreader) != RM_XACT_ID ||
1433  ereport(ERROR,
1435  errmsg("expected two-phase state data is not present in WAL at %X/%X",
1436  LSN_FORMAT_ARGS(lsn))));
1437 
1438  if (len != NULL)
1440 
1441  *buf = palloc(sizeof(char) * XLogRecGetDataLen(xlogreader));
1442  memcpy(*buf, XLogRecGetData(xlogreader), sizeof(char) * XLogRecGetDataLen(xlogreader));
1443 
1445 }
1446 
1447 
1448 /*
1449  * Confirms an xid is prepared, during recovery
1450  */
1451 bool
1453 {
1454  char *buf;
1455  TwoPhaseFileHeader *hdr;
1456  bool result;
1457 
1459 
1460  if (max_prepared_xacts <= 0)
1461  return false; /* nothing to do */
1462 
1463  /* Read and validate file */
1464  buf = ReadTwoPhaseFile(xid, true);
1465  if (buf == NULL)
1466  return false;
1467 
1468  /* Check header also */
1469  hdr = (TwoPhaseFileHeader *) buf;
1470  result = TransactionIdEquals(hdr->xid, xid);
1471  pfree(buf);
1472 
1473  return result;
1474 }
1475 
1476 /*
1477  * FinishPreparedTransaction: execute COMMIT PREPARED or ROLLBACK PREPARED
1478  */
1479 void
1480 FinishPreparedTransaction(const char *gid, bool isCommit)
1481 {
1482  GlobalTransaction gxact;
1483  PGPROC *proc;
1484  TransactionId xid;
1485  char *buf;
1486  char *bufptr;
1487  TwoPhaseFileHeader *hdr;
1488  TransactionId latestXid;
1489  TransactionId *children;
1490  RelFileLocator *commitrels;
1491  RelFileLocator *abortrels;
1492  RelFileLocator *delrels;
1493  int ndelrels;
1494  xl_xact_stats_item *commitstats;
1495  xl_xact_stats_item *abortstats;
1496  SharedInvalidationMessage *invalmsgs;
1497 
1498  /*
1499  * Validate the GID, and lock the GXACT to ensure that two backends do not
1500  * try to commit the same GID at once.
1501  */
1502  gxact = LockGXact(gid, GetUserId());
1503  proc = &ProcGlobal->allProcs[gxact->pgprocno];
1504  xid = gxact->xid;
1505 
1506  /*
1507  * Read and validate 2PC state data. State data will typically be stored
1508  * in WAL files if the LSN is after the last checkpoint record, or moved
1509  * to disk if for some reason they have lived for a long time.
1510  */
1511  if (gxact->ondisk)
1512  buf = ReadTwoPhaseFile(xid, false);
1513  else
1514  XlogReadTwoPhaseData(gxact->prepare_start_lsn, &buf, NULL);
1515 
1516 
1517  /*
1518  * Disassemble the header area
1519  */
1520  hdr = (TwoPhaseFileHeader *) buf;
1521  Assert(TransactionIdEquals(hdr->xid, xid));
1522  bufptr = buf + MAXALIGN(sizeof(TwoPhaseFileHeader));
1523  bufptr += MAXALIGN(hdr->gidlen);
1524  children = (TransactionId *) bufptr;
1525  bufptr += MAXALIGN(hdr->nsubxacts * sizeof(TransactionId));
1526  commitrels = (RelFileLocator *) bufptr;
1527  bufptr += MAXALIGN(hdr->ncommitrels * sizeof(RelFileLocator));
1528  abortrels = (RelFileLocator *) bufptr;
1529  bufptr += MAXALIGN(hdr->nabortrels * sizeof(RelFileLocator));
1530  commitstats = (xl_xact_stats_item *) bufptr;
1531  bufptr += MAXALIGN(hdr->ncommitstats * sizeof(xl_xact_stats_item));
1532  abortstats = (xl_xact_stats_item *) bufptr;
1533  bufptr += MAXALIGN(hdr->nabortstats * sizeof(xl_xact_stats_item));
1534  invalmsgs = (SharedInvalidationMessage *) bufptr;
1535  bufptr += MAXALIGN(hdr->ninvalmsgs * sizeof(SharedInvalidationMessage));
1536 
1537  /* compute latestXid among all children */
1538  latestXid = TransactionIdLatest(xid, hdr->nsubxacts, children);
1539 
1540  /* Prevent cancel/die interrupt while cleaning up */
1541  HOLD_INTERRUPTS();
1542 
1543  /*
1544  * The order of operations here is critical: make the XLOG entry for
1545  * commit or abort, then mark the transaction committed or aborted in
1546  * pg_xact, then remove its PGPROC from the global ProcArray (which means
1547  * TransactionIdIsInProgress will stop saying the prepared xact is in
1548  * progress), then run the post-commit or post-abort callbacks. The
1549  * callbacks will release the locks the transaction held.
1550  */
1551  if (isCommit)
1553  hdr->nsubxacts, children,
1554  hdr->ncommitrels, commitrels,
1555  hdr->ncommitstats,
1556  commitstats,
1557  hdr->ninvalmsgs, invalmsgs,
1558  hdr->initfileinval, gid);
1559  else
1561  hdr->nsubxacts, children,
1562  hdr->nabortrels, abortrels,
1563  hdr->nabortstats,
1564  abortstats,
1565  gid);
1566 
1567  ProcArrayRemove(proc, latestXid);
1568 
1569  /*
1570  * In case we fail while running the callbacks, mark the gxact invalid so
1571  * no one else will try to commit/rollback, and so it will be recycled if
1572  * we fail after this point. It is still locked by our backend so it
1573  * won't go away yet.
1574  *
1575  * (We assume it's safe to do this without taking TwoPhaseStateLock.)
1576  */
1577  gxact->valid = false;
1578 
1579  /*
1580  * We have to remove any files that were supposed to be dropped. For
1581  * consistency with the regular xact.c code paths, must do this before
1582  * releasing locks, so do it before running the callbacks.
1583  *
1584  * NB: this code knows that we couldn't be dropping any temp rels ...
1585  */
1586  if (isCommit)
1587  {
1588  delrels = commitrels;
1589  ndelrels = hdr->ncommitrels;
1590  }
1591  else
1592  {
1593  delrels = abortrels;
1594  ndelrels = hdr->nabortrels;
1595  }
1596 
1597  /* Make sure files supposed to be dropped are dropped */
1598  DropRelationFiles(delrels, ndelrels, false);
1599 
1600  if (isCommit)
1601  pgstat_execute_transactional_drops(hdr->ncommitstats, commitstats, false);
1602  else
1603  pgstat_execute_transactional_drops(hdr->nabortstats, abortstats, false);
1604 
1605  /*
1606  * Handle cache invalidation messages.
1607  *
1608  * Relcache init file invalidation requires processing both before and
1609  * after we send the SI messages, only when committing. See
1610  * AtEOXact_Inval().
1611  */
1612  if (isCommit)
1613  {
1614  if (hdr->initfileinval)
1616  SendSharedInvalidMessages(invalmsgs, hdr->ninvalmsgs);
1617  if (hdr->initfileinval)
1619  }
1620 
1621  /*
1622  * Acquire the two-phase lock. We want to work on the two-phase callbacks
1623  * while holding it to avoid potential conflicts with other transactions
1624  * attempting to use the same GID, so the lock is released once the shared
1625  * memory state is cleared.
1626  */
1627  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
1628 
1629  /* And now do the callbacks */
1630  if (isCommit)
1632  else
1634 
1635  PredicateLockTwoPhaseFinish(xid, isCommit);
1636 
1637  /* Clear shared memory state */
1638  RemoveGXact(gxact);
1639 
1640  /*
1641  * Release the lock as all callbacks are called and shared memory cleanup
1642  * is done.
1643  */
1644  LWLockRelease(TwoPhaseStateLock);
1645 
1646  /* Count the prepared xact as committed or aborted */
1647  AtEOXact_PgStat(isCommit, false);
1648 
1649  /*
1650  * And now we can clean up any files we may have left.
1651  */
1652  if (gxact->ondisk)
1653  RemoveTwoPhaseFile(xid, true);
1654 
1655  MyLockedGxact = NULL;
1656 
1658 
1659  pfree(buf);
1660 }
1661 
1662 /*
1663  * Scan 2PC state data in memory and call the indicated callbacks for each 2PC record.
1664  */
1665 static void
1666 ProcessRecords(char *bufptr, TransactionId xid,
1667  const TwoPhaseCallback callbacks[])
1668 {
1669  for (;;)
1670  {
1671  TwoPhaseRecordOnDisk *record = (TwoPhaseRecordOnDisk *) bufptr;
1672 
1673  Assert(record->rmid <= TWOPHASE_RM_MAX_ID);
1674  if (record->rmid == TWOPHASE_RM_END_ID)
1675  break;
1676 
1677  bufptr += MAXALIGN(sizeof(TwoPhaseRecordOnDisk));
1678 
1679  if (callbacks[record->rmid] != NULL)
1680  callbacks[record->rmid] (xid, record->info,
1681  (void *) bufptr, record->len);
1682 
1683  bufptr += MAXALIGN(record->len);
1684  }
1685 }
1686 
1687 /*
1688  * Remove the 2PC file for the specified XID.
1689  *
1690  * If giveWarning is false, do not complain about file-not-present;
1691  * this is an expected case during WAL replay.
1692  */
1693 static void
1694 RemoveTwoPhaseFile(TransactionId xid, bool giveWarning)
1695 {
1696  char path[MAXPGPATH];
1697 
1698  TwoPhaseFilePath(path, xid);
1699  if (unlink(path))
1700  if (errno != ENOENT || giveWarning)
1701  ereport(WARNING,
1703  errmsg("could not remove file \"%s\": %m", path)));
1704 }
1705 
1706 /*
1707  * Recreates a state file. This is used in WAL replay and during
1708  * checkpoint creation.
1709  *
1710  * Note: content and len don't include CRC.
1711  */
1712 static void
1713 RecreateTwoPhaseFile(TransactionId xid, void *content, int len)
1714 {
1715  char path[MAXPGPATH];
1716  pg_crc32c statefile_crc;
1717  int fd;
1718 
1719  /* Recompute CRC */
1720  INIT_CRC32C(statefile_crc);
1721  COMP_CRC32C(statefile_crc, content, len);
1722  FIN_CRC32C(statefile_crc);
1723 
1724  TwoPhaseFilePath(path, xid);
1725 
1726  fd = OpenTransientFile(path,
1727  O_CREAT | O_TRUNC | O_WRONLY | PG_BINARY);
1728  if (fd < 0)
1729  ereport(ERROR,
1731  errmsg("could not recreate file \"%s\": %m", path)));
1732 
1733  /* Write content and CRC */
1734  errno = 0;
1736  if (write(fd, content, len) != len)
1737  {
1738  /* if write didn't set errno, assume problem is no disk space */
1739  if (errno == 0)
1740  errno = ENOSPC;
1741  ereport(ERROR,
1743  errmsg("could not write file \"%s\": %m", path)));
1744  }
1745  if (write(fd, &statefile_crc, sizeof(pg_crc32c)) != sizeof(pg_crc32c))
1746  {
1747  /* if write didn't set errno, assume problem is no disk space */
1748  if (errno == 0)
1749  errno = ENOSPC;
1750  ereport(ERROR,
1752  errmsg("could not write file \"%s\": %m", path)));
1753  }
1755 
1756  /*
1757  * We must fsync the file because the end-of-replay checkpoint will not do
1758  * so, there being no GXACT in shared memory yet to tell it to.
1759  */
1761  if (pg_fsync(fd) != 0)
1762  ereport(ERROR,
1764  errmsg("could not fsync file \"%s\": %m", path)));
1766 
1767  if (CloseTransientFile(fd) != 0)
1768  ereport(ERROR,
1770  errmsg("could not close file \"%s\": %m", path)));
1771 }
1772 
1773 /*
1774  * CheckPointTwoPhase -- handle 2PC component of checkpointing.
1775  *
1776  * We must fsync the state file of any GXACT that is valid or has been
1777  * generated during redo and has a PREPARE LSN <= the checkpoint's redo
1778  * horizon. (If the gxact isn't valid yet, has not been generated in
1779  * redo, or has a later LSN, this checkpoint is not responsible for
1780  * fsyncing it.)
1781  *
1782  * This is deliberately run as late as possible in the checkpoint sequence,
1783  * because GXACTs ordinarily have short lifespans, and so it is quite
1784  * possible that GXACTs that were valid at checkpoint start will no longer
1785  * exist if we wait a little bit. With typical checkpoint settings this
1786  * will be about 3 minutes for an online checkpoint, so as a result we
1787  * expect that there will be no GXACTs that need to be copied to disk.
1788  *
1789  * If a GXACT remains valid across multiple checkpoints, it will already
1790  * be on disk so we don't bother to repeat that write.
1791  */
1792 void
1794 {
1795  int i;
1796  int serialized_xacts = 0;
1797 
1798  if (max_prepared_xacts <= 0)
1799  return; /* nothing to do */
1800 
1801  TRACE_POSTGRESQL_TWOPHASE_CHECKPOINT_START();
1802 
1803  /*
1804  * We are expecting there to be zero GXACTs that need to be copied to
1805  * disk, so we perform all I/O while holding TwoPhaseStateLock for
1806  * simplicity. This prevents any new xacts from preparing while this
1807  * occurs, which shouldn't be a problem since the presence of long-lived
1808  * prepared xacts indicates the transaction manager isn't active.
1809  *
1810  * It's also possible to move I/O out of the lock, but on every error we
1811  * should check whether somebody committed our transaction in different
1812  * backend. Let's leave this optimization for future, if somebody will
1813  * spot that this place cause bottleneck.
1814  *
1815  * Note that it isn't possible for there to be a GXACT with a
1816  * prepare_end_lsn set prior to the last checkpoint yet is marked invalid,
1817  * because of the efforts with delayChkptFlags.
1818  */
1819  LWLockAcquire(TwoPhaseStateLock, LW_SHARED);
1820  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
1821  {
1822  /*
1823  * Note that we are using gxact not PGPROC so this works in recovery
1824  * also
1825  */
1827 
1828  if ((gxact->valid || gxact->inredo) &&
1829  !gxact->ondisk &&
1830  gxact->prepare_end_lsn <= redo_horizon)
1831  {
1832  char *buf;
1833  int len;
1834 
1836  RecreateTwoPhaseFile(gxact->xid, buf, len);
1837  gxact->ondisk = true;
1840  pfree(buf);
1841  serialized_xacts++;
1842  }
1843  }
1844  LWLockRelease(TwoPhaseStateLock);
1845 
1846  /*
1847  * Flush unconditionally the parent directory to make any information
1848  * durable on disk. Two-phase files could have been removed and those
1849  * removals need to be made persistent as well as any files newly created
1850  * previously since the last checkpoint.
1851  */
1852  fsync_fname(TWOPHASE_DIR, true);
1853 
1854  TRACE_POSTGRESQL_TWOPHASE_CHECKPOINT_DONE();
1855 
1856  if (log_checkpoints && serialized_xacts > 0)
1857  ereport(LOG,
1858  (errmsg_plural("%u two-phase state file was written "
1859  "for a long-running prepared transaction",
1860  "%u two-phase state files were written "
1861  "for long-running prepared transactions",
1862  serialized_xacts,
1863  serialized_xacts)));
1864 }
1865 
1866 /*
1867  * restoreTwoPhaseData
1868  *
1869  * Scan pg_twophase and fill TwoPhaseState depending on the on-disk data.
1870  * This is called once at the beginning of recovery, saving any extra
1871  * lookups in the future. Two-phase files that are newer than the
1872  * minimum XID horizon are discarded on the way.
1873  */
1874 void
1876 {
1877  DIR *cldir;
1878  struct dirent *clde;
1879 
1880  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
1881  cldir = AllocateDir(TWOPHASE_DIR);
1882  while ((clde = ReadDir(cldir, TWOPHASE_DIR)) != NULL)
1883  {
1884  if (strlen(clde->d_name) == 8 &&
1885  strspn(clde->d_name, "0123456789ABCDEF") == 8)
1886  {
1887  TransactionId xid;
1888  char *buf;
1889 
1890  xid = (TransactionId) strtoul(clde->d_name, NULL, 16);
1891 
1893  true, false, false);
1894  if (buf == NULL)
1895  continue;
1896 
1899  }
1900  }
1901  LWLockRelease(TwoPhaseStateLock);
1902  FreeDir(cldir);
1903 }
1904 
1905 /*
1906  * PrescanPreparedTransactions
1907  *
1908  * Scan the shared memory entries of TwoPhaseState and determine the range
1909  * of valid XIDs present. This is run during database startup, after we
1910  * have completed reading WAL. ShmemVariableCache->nextXid has been set to
1911  * one more than the highest XID for which evidence exists in WAL.
1912  *
1913  * We throw away any prepared xacts with main XID beyond nextXid --- if any
1914  * are present, it suggests that the DBA has done a PITR recovery to an
1915  * earlier point in time without cleaning out pg_twophase. We dare not
1916  * try to recover such prepared xacts since they likely depend on database
1917  * state that doesn't exist now.
1918  *
1919  * However, we will advance nextXid beyond any subxact XIDs belonging to
1920  * valid prepared xacts. We need to do this since subxact commit doesn't
1921  * write a WAL entry, and so there might be no evidence in WAL of those
1922  * subxact XIDs.
1923  *
1924  * On corrupted two-phase files, fail immediately. Keeping around broken
1925  * entries and let replay continue causes harm on the system, and a new
1926  * backup should be rolled in.
1927  *
1928  * Our other responsibility is to determine and return the oldest valid XID
1929  * among the prepared xacts (if none, return ShmemVariableCache->nextXid).
1930  * This is needed to synchronize pg_subtrans startup properly.
1931  *
1932  * If xids_p and nxids_p are not NULL, pointer to a palloc'd array of all
1933  * top-level xids is stored in *xids_p. The number of entries in the array
1934  * is returned in *nxids_p.
1935  */
1938 {
1940  TransactionId origNextXid = XidFromFullTransactionId(nextXid);
1941  TransactionId result = origNextXid;
1942  TransactionId *xids = NULL;
1943  int nxids = 0;
1944  int allocsize = 0;
1945  int i;
1946 
1947  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
1948  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
1949  {
1950  TransactionId xid;
1951  char *buf;
1953 
1954  Assert(gxact->inredo);
1955 
1956  xid = gxact->xid;
1957 
1958  buf = ProcessTwoPhaseBuffer(xid,
1959  gxact->prepare_start_lsn,
1960  gxact->ondisk, false, true);
1961 
1962  if (buf == NULL)
1963  continue;
1964 
1965  /*
1966  * OK, we think this file is valid. Incorporate xid into the
1967  * running-minimum result.
1968  */
1969  if (TransactionIdPrecedes(xid, result))
1970  result = xid;
1971 
1972  if (xids_p)
1973  {
1974  if (nxids == allocsize)
1975  {
1976  if (nxids == 0)
1977  {
1978  allocsize = 10;
1979  xids = palloc(allocsize * sizeof(TransactionId));
1980  }
1981  else
1982  {
1983  allocsize = allocsize * 2;
1984  xids = repalloc(xids, allocsize * sizeof(TransactionId));
1985  }
1986  }
1987  xids[nxids++] = xid;
1988  }
1989 
1990  pfree(buf);
1991  }
1992  LWLockRelease(TwoPhaseStateLock);
1993 
1994  if (xids_p)
1995  {
1996  *xids_p = xids;
1997  *nxids_p = nxids;
1998  }
1999 
2000  return result;
2001 }
2002 
2003 /*
2004  * StandbyRecoverPreparedTransactions
2005  *
2006  * Scan the shared memory entries of TwoPhaseState and setup all the required
2007  * information to allow standby queries to treat prepared transactions as still
2008  * active.
2009  *
2010  * This is never called at the end of recovery - we use
2011  * RecoverPreparedTransactions() at that point.
2012  *
2013  * The lack of calls to SubTransSetParent() calls here is by design;
2014  * those calls are made by RecoverPreparedTransactions() at the end of recovery
2015  * for those xacts that need this.
2016  */
2017 void
2019 {
2020  int i;
2021 
2022  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
2023  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
2024  {
2025  TransactionId xid;
2026  char *buf;
2028 
2029  Assert(gxact->inredo);
2030 
2031  xid = gxact->xid;
2032 
2033  buf = ProcessTwoPhaseBuffer(xid,
2034  gxact->prepare_start_lsn,
2035  gxact->ondisk, false, false);
2036  if (buf != NULL)
2037  pfree(buf);
2038  }
2039  LWLockRelease(TwoPhaseStateLock);
2040 }
2041 
2042 /*
2043  * RecoverPreparedTransactions
2044  *
2045  * Scan the shared memory entries of TwoPhaseState and reload the state for
2046  * each prepared transaction (reacquire locks, etc).
2047  *
2048  * This is run at the end of recovery, but before we allow backends to write
2049  * WAL.
2050  *
2051  * At the end of recovery the way we take snapshots will change. We now need
2052  * to mark all running transactions with their full SubTransSetParent() info
2053  * to allow normal snapshots to work correctly if snapshots overflow.
2054  * We do this here because by definition prepared transactions are the only
2055  * type of write transaction still running, so this is necessary and
2056  * complete.
2057  */
2058 void
2060 {
2061  int i;
2062 
2063  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
2064  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
2065  {
2066  TransactionId xid;
2067  char *buf;
2069  char *bufptr;
2070  TwoPhaseFileHeader *hdr;
2071  TransactionId *subxids;
2072  const char *gid;
2073 
2074  xid = gxact->xid;
2075 
2076  /*
2077  * Reconstruct subtrans state for the transaction --- needed because
2078  * pg_subtrans is not preserved over a restart. Note that we are
2079  * linking all the subtransactions directly to the top-level XID;
2080  * there may originally have been a more complex hierarchy, but
2081  * there's no need to restore that exactly. It's possible that
2082  * SubTransSetParent has been set before, if the prepared transaction
2083  * generated xid assignment records.
2084  */
2085  buf = ProcessTwoPhaseBuffer(xid,
2086  gxact->prepare_start_lsn,
2087  gxact->ondisk, true, false);
2088  if (buf == NULL)
2089  continue;
2090 
2091  ereport(LOG,
2092  (errmsg("recovering prepared transaction %u from shared memory", xid)));
2093 
2094  hdr = (TwoPhaseFileHeader *) buf;
2095  Assert(TransactionIdEquals(hdr->xid, xid));
2096  bufptr = buf + MAXALIGN(sizeof(TwoPhaseFileHeader));
2097  gid = (const char *) bufptr;
2098  bufptr += MAXALIGN(hdr->gidlen);
2099  subxids = (TransactionId *) bufptr;
2100  bufptr += MAXALIGN(hdr->nsubxacts * sizeof(TransactionId));
2101  bufptr += MAXALIGN(hdr->ncommitrels * sizeof(RelFileLocator));
2102  bufptr += MAXALIGN(hdr->nabortrels * sizeof(RelFileLocator));
2103  bufptr += MAXALIGN(hdr->ncommitstats * sizeof(xl_xact_stats_item));
2104  bufptr += MAXALIGN(hdr->nabortstats * sizeof(xl_xact_stats_item));
2105  bufptr += MAXALIGN(hdr->ninvalmsgs * sizeof(SharedInvalidationMessage));
2106 
2107  /*
2108  * Recreate its GXACT and dummy PGPROC. But, check whether it was
2109  * added in redo and already has a shmem entry for it.
2110  */
2111  MarkAsPreparingGuts(gxact, xid, gid,
2112  hdr->prepared_at,
2113  hdr->owner, hdr->database);
2114 
2115  /* recovered, so reset the flag for entries generated by redo */
2116  gxact->inredo = false;
2117 
2118  GXactLoadSubxactData(gxact, hdr->nsubxacts, subxids);
2119  MarkAsPrepared(gxact, true);
2120 
2121  LWLockRelease(TwoPhaseStateLock);
2122 
2123  /*
2124  * Recover other state (notably locks) using resource managers.
2125  */
2127 
2128  /*
2129  * Release locks held by the standby process after we process each
2130  * prepared transaction. As a result, we don't need too many
2131  * additional locks at any one time.
2132  */
2133  if (InHotStandby)
2134  StandbyReleaseLockTree(xid, hdr->nsubxacts, subxids);
2135 
2136  /*
2137  * We're done with recovering this transaction. Clear MyLockedGxact,
2138  * like we do in PrepareTransaction() during normal operation.
2139  */
2141 
2142  pfree(buf);
2143 
2144  LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
2145  }
2146 
2147  LWLockRelease(TwoPhaseStateLock);
2148 }
2149 
2150 /*
2151  * ProcessTwoPhaseBuffer
2152  *
2153  * Given a transaction id, read it either from disk or read it directly
2154  * via shmem xlog record pointer using the provided "prepare_start_lsn".
2155  *
2156  * If setParent is true, set up subtransaction parent linkages.
2157  *
2158  * If setNextXid is true, set ShmemVariableCache->nextXid to the newest
2159  * value scanned.
2160  */
2161 static char *
2163  XLogRecPtr prepare_start_lsn,
2164  bool fromdisk,
2165  bool setParent, bool setNextXid)
2166 {
2168  TransactionId origNextXid = XidFromFullTransactionId(nextXid);
2169  TransactionId *subxids;
2170  char *buf;
2171  TwoPhaseFileHeader *hdr;
2172  int i;
2173 
2174  Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
2175 
2176  if (!fromdisk)
2177  Assert(prepare_start_lsn != InvalidXLogRecPtr);
2178 
2179  /* Already processed? */
2181  {
2182  if (fromdisk)
2183  {
2184  ereport(WARNING,
2185  (errmsg("removing stale two-phase state file for transaction %u",
2186  xid)));
2187  RemoveTwoPhaseFile(xid, true);
2188  }
2189  else
2190  {
2191  ereport(WARNING,
2192  (errmsg("removing stale two-phase state from memory for transaction %u",
2193  xid)));
2194  PrepareRedoRemove(xid, true);
2195  }
2196  return NULL;
2197  }
2198 
2199  /* Reject XID if too new */
2200  if (TransactionIdFollowsOrEquals(xid, origNextXid))
2201  {
2202  if (fromdisk)
2203  {
2204  ereport(WARNING,
2205  (errmsg("removing future two-phase state file for transaction %u",
2206  xid)));
2207  RemoveTwoPhaseFile(xid, true);
2208  }
2209  else
2210  {
2211  ereport(WARNING,
2212  (errmsg("removing future two-phase state from memory for transaction %u",
2213  xid)));
2214  PrepareRedoRemove(xid, true);
2215  }
2216  return NULL;
2217  }
2218 
2219  if (fromdisk)
2220  {
2221  /* Read and validate file */
2222  buf = ReadTwoPhaseFile(xid, false);
2223  }
2224  else
2225  {
2226  /* Read xlog data */
2227  XlogReadTwoPhaseData(prepare_start_lsn, &buf, NULL);
2228  }
2229 
2230  /* Deconstruct header */
2231  hdr = (TwoPhaseFileHeader *) buf;
2232  if (!TransactionIdEquals(hdr->xid, xid))
2233  {
2234  if (fromdisk)
2235  ereport(ERROR,
2237  errmsg("corrupted two-phase state file for transaction %u",
2238  xid)));
2239  else
2240  ereport(ERROR,
2242  errmsg("corrupted two-phase state in memory for transaction %u",
2243  xid)));
2244  }
2245 
2246  /*
2247  * Examine subtransaction XIDs ... they should all follow main XID, and
2248  * they may force us to advance nextXid.
2249  */
2250  subxids = (TransactionId *) (buf +
2251  MAXALIGN(sizeof(TwoPhaseFileHeader)) +
2252  MAXALIGN(hdr->gidlen));
2253  for (i = 0; i < hdr->nsubxacts; i++)
2254  {
2255  TransactionId subxid = subxids[i];
2256 
2257  Assert(TransactionIdFollows(subxid, xid));
2258 
2259  /* update nextXid if needed */
2260  if (setNextXid)
2262 
2263  if (setParent)
2264  SubTransSetParent(subxid, xid);
2265  }
2266 
2267  return buf;
2268 }
2269 
2270 
2271 /*
2272  * RecordTransactionCommitPrepared
2273  *
2274  * This is basically the same as RecordTransactionCommit (q.v. if you change
2275  * this function): in particular, we must set DELAY_CHKPT_START to avoid a
2276  * race condition.
2277  *
2278  * We know the transaction made at least one XLOG entry (its PREPARE),
2279  * so it is never possible to optimize out the commit record.
2280  */
2281 static void
2283  int nchildren,
2284  TransactionId *children,
2285  int nrels,
2286  RelFileLocator *rels,
2287  int nstats,
2288  xl_xact_stats_item *stats,
2289  int ninvalmsgs,
2290  SharedInvalidationMessage *invalmsgs,
2291  bool initfileinval,
2292  const char *gid)
2293 {
2294  XLogRecPtr recptr;
2295  TimestampTz committs = GetCurrentTimestamp();
2296  bool replorigin;
2297 
2298  /*
2299  * Are we using the replication origins feature? Or, in other words, are
2300  * we replaying remote actions?
2301  */
2302  replorigin = (replorigin_session_origin != InvalidRepOriginId &&
2304 
2306 
2307  /* See notes in RecordTransactionCommit */
2310 
2311  /*
2312  * Emit the XLOG commit record. Note that we mark 2PC commits as
2313  * potentially having AccessExclusiveLocks since we don't know whether or
2314  * not they do.
2315  */
2316  recptr = XactLogCommitRecord(committs,
2317  nchildren, children, nrels, rels,
2318  nstats, stats,
2319  ninvalmsgs, invalmsgs,
2320  initfileinval,
2322  xid, gid);
2323 
2324 
2325  if (replorigin)
2326  /* Move LSNs forward for this replication origin */
2328  XactLastRecEnd);
2329 
2330  /*
2331  * Record commit timestamp. The value comes from plain commit timestamp
2332  * if replorigin is not enabled, or replorigin already set a value for us
2333  * in replorigin_session_origin_timestamp otherwise.
2334  *
2335  * We don't need to WAL-log anything here, as the commit record written
2336  * above already contains the data.
2337  */
2338  if (!replorigin || replorigin_session_origin_timestamp == 0)
2340 
2341  TransactionTreeSetCommitTsData(xid, nchildren, children,
2344 
2345  /*
2346  * We don't currently try to sleep before flush here ... nor is there any
2347  * support for async commit of a prepared xact (the very idea is probably
2348  * a contradiction)
2349  */
2350 
2351  /* Flush XLOG to disk */
2352  XLogFlush(recptr);
2353 
2354  /* Mark the transaction committed in pg_xact */
2355  TransactionIdCommitTree(xid, nchildren, children);
2356 
2357  /* Checkpoint can proceed now */
2359 
2360  END_CRIT_SECTION();
2361 
2362  /*
2363  * Wait for synchronous replication, if required.
2364  *
2365  * Note that at this stage we have marked clog, but still show as running
2366  * in the procarray and continue to hold locks.
2367  */
2368  SyncRepWaitForLSN(recptr, true);
2369 }
2370 
2371 /*
2372  * RecordTransactionAbortPrepared
2373  *
2374  * This is basically the same as RecordTransactionAbort.
2375  *
2376  * We know the transaction made at least one XLOG entry (its PREPARE),
2377  * so it is never possible to optimize out the abort record.
2378  */
2379 static void
2381  int nchildren,
2382  TransactionId *children,
2383  int nrels,
2384  RelFileLocator *rels,
2385  int nstats,
2386  xl_xact_stats_item *stats,
2387  const char *gid)
2388 {
2389  XLogRecPtr recptr;
2390  bool replorigin;
2391 
2392  /*
2393  * Are we using the replication origins feature? Or, in other words, are
2394  * we replaying remote actions?
2395  */
2396  replorigin = (replorigin_session_origin != InvalidRepOriginId &&
2398 
2399  /*
2400  * Catch the scenario where we aborted partway through
2401  * RecordTransactionCommitPrepared ...
2402  */
2403  if (TransactionIdDidCommit(xid))
2404  elog(PANIC, "cannot abort transaction %u, it was already committed",
2405  xid);
2406 
2408 
2409  /*
2410  * Emit the XLOG commit record. Note that we mark 2PC aborts as
2411  * potentially having AccessExclusiveLocks since we don't know whether or
2412  * not they do.
2413  */
2415  nchildren, children,
2416  nrels, rels,
2417  nstats, stats,
2419  xid, gid);
2420 
2421  if (replorigin)
2422  /* Move LSNs forward for this replication origin */
2424  XactLastRecEnd);
2425 
2426  /* Always flush, since we're about to remove the 2PC state file */
2427  XLogFlush(recptr);
2428 
2429  /*
2430  * Mark the transaction aborted in clog. This is not absolutely necessary
2431  * but we may as well do it while we are here.
2432  */
2433  TransactionIdAbortTree(xid, nchildren, children);
2434 
2435  END_CRIT_SECTION();
2436 
2437  /*
2438  * Wait for synchronous replication, if required.
2439  *
2440  * Note that at this stage we have marked clog, but still show as running
2441  * in the procarray and continue to hold locks.
2442  */
2443  SyncRepWaitForLSN(recptr, false);
2444 }
2445 
2446 /*
2447  * PrepareRedoAdd
2448  *
2449  * Store pointers to the start/end of the WAL record along with the xid in
2450  * a gxact entry in shared memory TwoPhaseState structure. If caller
2451  * specifies InvalidXLogRecPtr as WAL location to fetch the two-phase
2452  * data, the entry is marked as located on disk.
2453  */
2454 void
2455 PrepareRedoAdd(char *buf, XLogRecPtr start_lsn,
2456  XLogRecPtr end_lsn, RepOriginId origin_id)
2457 {
2459  char *bufptr;
2460  const char *gid;
2461  GlobalTransaction gxact;
2462 
2463  Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
2465 
2466  bufptr = buf + MAXALIGN(sizeof(TwoPhaseFileHeader));
2467  gid = (const char *) bufptr;
2468 
2469  /*
2470  * Reserve the GID for the given transaction in the redo code path.
2471  *
2472  * This creates a gxact struct and puts it into the active array.
2473  *
2474  * In redo, this struct is mainly used to track PREPARE/COMMIT entries in
2475  * shared memory. Hence, we only fill up the bare minimum contents here.
2476  * The gxact also gets marked with gxact->inredo set to true to indicate
2477  * that it got added in the redo phase
2478  */
2479 
2480  /* Get a free gxact from the freelist */
2481  if (TwoPhaseState->freeGXacts == NULL)
2482  ereport(ERROR,
2483  (errcode(ERRCODE_OUT_OF_MEMORY),
2484  errmsg("maximum number of prepared transactions reached"),
2485  errhint("Increase max_prepared_transactions (currently %d).",
2486  max_prepared_xacts)));
2487  gxact = TwoPhaseState->freeGXacts;
2488  TwoPhaseState->freeGXacts = gxact->next;
2489 
2490  gxact->prepared_at = hdr->prepared_at;
2491  gxact->prepare_start_lsn = start_lsn;
2492  gxact->prepare_end_lsn = end_lsn;
2493  gxact->xid = hdr->xid;
2494  gxact->owner = hdr->owner;
2496  gxact->valid = false;
2497  gxact->ondisk = XLogRecPtrIsInvalid(start_lsn);
2498  gxact->inredo = true; /* yes, added in redo */
2499  strcpy(gxact->gid, gid);
2500 
2501  /* And insert it into the active array */
2504 
2505  if (origin_id != InvalidRepOriginId)
2506  {
2507  /* recover apply progress */
2508  replorigin_advance(origin_id, hdr->origin_lsn, end_lsn,
2509  false /* backward */ , false /* WAL */ );
2510  }
2511 
2512  elog(DEBUG2, "added 2PC data in shared memory for transaction %u", gxact->xid);
2513 }
2514 
2515 /*
2516  * PrepareRedoRemove
2517  *
2518  * Remove the corresponding gxact entry from TwoPhaseState. Also remove
2519  * the 2PC file if a prepared transaction was saved via an earlier checkpoint.
2520  *
2521  * Caller must hold TwoPhaseStateLock in exclusive mode, because TwoPhaseState
2522  * is updated.
2523  */
2524 void
2525 PrepareRedoRemove(TransactionId xid, bool giveWarning)
2526 {
2527  GlobalTransaction gxact = NULL;
2528  int i;
2529  bool found = false;
2530 
2531  Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
2533 
2534  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
2535  {
2536  gxact = TwoPhaseState->prepXacts[i];
2537 
2538  if (gxact->xid == xid)
2539  {
2540  Assert(gxact->inredo);
2541  found = true;
2542  break;
2543  }
2544  }
2545 
2546  /*
2547  * Just leave if there is nothing, this is expected during WAL replay.
2548  */
2549  if (!found)
2550  return;
2551 
2552  /*
2553  * And now we can clean up any files we may have left.
2554  */
2555  elog(DEBUG2, "removing 2PC data for transaction %u", xid);
2556  if (gxact->ondisk)
2557  RemoveTwoPhaseFile(xid, giveWarning);
2558  RemoveGXact(gxact);
2559 }
2560 
2561 /*
2562  * LookupGXact
2563  * Check if the prepared transaction with the given GID, lsn and timestamp
2564  * exists.
2565  *
2566  * Note that we always compare with the LSN where prepare ends because that is
2567  * what is stored as origin_lsn in the 2PC file.
2568  *
2569  * This function is primarily used to check if the prepared transaction
2570  * received from the upstream (remote node) already exists. Checking only GID
2571  * is not sufficient because a different prepared xact with the same GID can
2572  * exist on the same node. So, we are ensuring to match origin_lsn and
2573  * origin_timestamp of prepared xact to avoid the possibility of a match of
2574  * prepared xact from two different nodes.
2575  */
2576 bool
2577 LookupGXact(const char *gid, XLogRecPtr prepare_end_lsn,
2578  TimestampTz origin_prepare_timestamp)
2579 {
2580  int i;
2581  bool found = false;
2582 
2583  LWLockAcquire(TwoPhaseStateLock, LW_SHARED);
2584  for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
2585  {
2587 
2588  /* Ignore not-yet-valid GIDs. */
2589  if (gxact->valid && strcmp(gxact->gid, gid) == 0)
2590  {
2591  char *buf;
2592  TwoPhaseFileHeader *hdr;
2593 
2594  /*
2595  * We are not expecting collisions of GXACTs (same gid) between
2596  * publisher and subscribers, so we perform all I/O while holding
2597  * TwoPhaseStateLock for simplicity.
2598  *
2599  * To move the I/O out of the lock, we need to ensure that no
2600  * other backend commits the prepared xact in the meantime. We can
2601  * do this optimization if we encounter many collisions in GID
2602  * between publisher and subscriber.
2603  */
2604  if (gxact->ondisk)
2605  buf = ReadTwoPhaseFile(gxact->xid, false);
2606  else
2607  {
2608  Assert(gxact->prepare_start_lsn);
2609  XlogReadTwoPhaseData(gxact->prepare_start_lsn, &buf, NULL);
2610  }
2611 
2612  hdr = (TwoPhaseFileHeader *) buf;
2613 
2614  if (hdr->origin_lsn == prepare_end_lsn &&
2615  hdr->origin_timestamp == origin_prepare_timestamp)
2616  {
2617  found = true;
2618  pfree(buf);
2619  break;
2620  }
2621 
2622  pfree(buf);
2623  }
2624  }
2625  LWLockRelease(TwoPhaseStateLock);
2626  return found;
2627 }
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Definition: twophase.c:154
BackendId dummyBackendId
Definition: twophase.c:153
TransactionId xid
Definition: twophase.c:165
XLogRecPtr prepare_start_lsn
Definition: twophase.c:163
XLogRecPtr prepare_end_lsn
Definition: twophase.c:164
GlobalTransaction next
Definition: twophase.c:151
BackendId locking_backend
Definition: twophase.c:168
char gid[GIDSIZE]
Definition: twophase.c:172
Definition: proc.h:162
TransactionId xmin
Definition: proc.h:178
LocalTransactionId lxid
Definition: proc.h:183
PROCLOCK * waitProcLock
Definition: proc.h:220
SHM_QUEUE links
Definition: proc.h:164
uint8 lwWaitMode
Definition: proc.h:211
uint8 statusFlags
Definition: proc.h:229
Oid databaseId
Definition: proc.h:194
pg_atomic_uint64 waitStart
Definition: proc.h:224
BackendId backendId
Definition: proc.h:193
int pid
Definition: proc.h:186
bool isBackgroundWorker
Definition: proc.h:200
XidCacheStatus subxidStatus
Definition: proc.h:250
LOCK * waitLock
Definition: proc.h:219
TransactionId xid
Definition: proc.h:173
int pgprocno
Definition: proc.h:190
struct XidCache subxids
Definition: proc.h:252
bool lwWaiting
Definition: proc.h:210
int delayChkptFlags
Definition: proc.h:227
Oid roleId
Definition: proc.h:195
ProcWaitStatus waitStatus
Definition: proc.h:168
Oid tempNamespaceId
Definition: proc.h:197
SHM_QUEUE myProcLocks[NUM_LOCK_PARTITIONS]
Definition: proc.h:248
PGPROC * allProcs
Definition: proc.h:358
struct StateFileChunk * next
Definition: twophase.c:992
uint32 len
Definition: twophase.c:991
char * data
Definition: twophase.c:990
TwoPhaseRmgrId rmid
Definition: twophase.c:979
GlobalTransaction freeGXacts
Definition: twophase.c:182
GlobalTransaction prepXacts[FLEXIBLE_ARRAY_MEMBER]
Definition: twophase.c:188
FullTransactionId nextXid
Definition: transam.h:220
GlobalTransaction array
Definition: twophase.c:716
bool overflowed
Definition: proc.h:45
uint8 count
Definition: proc.h:43
TransactionId xids[PGPROC_MAX_CACHED_SUBXIDS]
Definition: proc.h:50
Definition: dirent.h:10
char d_name[MAX_PATH]
Definition: dirent.h:15
__int64 st_size
Definition: win32_port.h:275
TimestampTz prepared_at
Definition: xact.h:345
int32 nabortrels
Definition: xact.h:349
int32 ninvalmsgs
Definition: xact.h:352
bool initfileinval
Definition: xact.h:353
int32 ncommitstats
Definition: xact.h:350
TimestampTz origin_timestamp
Definition: xact.h:356
uint16 gidlen
Definition: xact.h:354
uint32 total_len
Definition: xact.h:342
int32 nabortstats
Definition: xact.h:351
Oid database
Definition: xact.h:344
XLogRecPtr origin_lsn
Definition: xact.h:355
uint32 magic
Definition: xact.h:341
int32 ncommitrels
Definition: xact.h:348
TransactionId xid
Definition: xact.h:343
int32 nsubxacts
Definition: xact.h:347
uint32 total_len
Definition: twophase.c:1001
uint32 num_chunks
Definition: twophase.c:999
StateFileChunk * head
Definition: twophase.c:997
StateFileChunk * tail
Definition: twophase.c:998
uint32 bytes_free
Definition: twophase.c:1000
void SubTransSetParent(TransactionId xid, TransactionId parent)
Definition: subtrans.c:74
bool superuser_arg(Oid roleid)
Definition: superuser.c:56
void SyncRepWaitForLSN(XLogRecPtr lsn, bool commit)
Definition: syncrep.c:149
TransactionId TransactionIdLatest(TransactionId mainxid, int nxids, const TransactionId *xids)
Definition: transam.c:338
bool TransactionIdDidCommit(TransactionId transactionId)
Definition: transam.c:125
void TransactionIdCommitTree(TransactionId xid, int nxids, TransactionId *xids)
Definition: transam.c:233
void TransactionIdAbortTree(TransactionId xid, int nxids, TransactionId *xids)
Definition: transam.c:263
bool TransactionIdPrecedes(TransactionId id1, TransactionId id2)
Definition: transam.c:273
bool TransactionIdDidAbort(TransactionId transactionId)
Definition: transam.c:181
bool TransactionIdFollows(TransactionId id1, TransactionId id2)
Definition: transam.c:307
bool TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2)
Definition: transam.c:322
#define InvalidTransactionId
Definition: transam.h:31
#define TransactionIdEquals(id1, id2)
Definition: transam.h:43
#define XidFromFullTransactionId(x)
Definition: transam.h:48
#define TransactionIdIsValid(xid)
Definition: transam.h:41
TupleDesc CreateTemplateTupleDesc(int natts)
Definition: tupdesc.c:45
void TupleDescInitEntry(TupleDesc desc, AttrNumber attributeNumber, const char *attributeName, Oid oidtypeid, int32 typmod, int attdim)
Definition: tupdesc.c:583
static void XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len)
Definition: twophase.c:1397
void RecoverPreparedTransactions(void)
Definition: twophase.c:2059
static bool twophaseExitRegistered
Definition: twophase.c:201
void restoreTwoPhaseData(void)
Definition: twophase.c:1875
bool LookupGXact(const char *gid, XLogRecPtr prepare_end_lsn, TimestampTz origin_prepare_timestamp)
Definition: twophase.c:2577
Size TwoPhaseShmemSize(void)
Definition: twophase.c:240
#define TWOPHASE_DIR
Definition: twophase.c:114
static void RecordTransactionAbortPrepared(TransactionId xid, int nchildren, TransactionId *children, int nrels, RelFileLocator *rels, int nstats, xl_xact_stats_item *stats, const char *gid)
Definition: twophase.c:2380
void RegisterTwoPhaseRecord(TwoPhaseRmgrId rmid, uint16 info, const void *data, uint32 len)
Definition: twophase.c:1257
int max_prepared_xacts
Definition: twophase.c:117
static void RecordTransactionCommitPrepared(TransactionId xid, int nchildren, TransactionId *children, int nrels, RelFileLocator *rels, int nstats, xl_xact_stats_item *stats, int ninvalmsgs, SharedInvalidationMessage *invalmsgs, bool initfileinval, const char *gid)
Definition: twophase.c:2282
static void RemoveGXact(GlobalTransaction gxact)
Definition: twophase.c:646
struct TwoPhaseStateData TwoPhaseStateData
static GlobalTransaction MyLockedGxact
Definition: twophase.c:199
static TwoPhaseStateData * TwoPhaseState
Definition: twophase.c:191
static void ProcessRecords(char *bufptr, TransactionId xid, const TwoPhaseCallback callbacks[])
Definition: twophase.c:1666
void AtAbort_Twophase(void)
Definition: twophase.c:321
BackendId TwoPhaseGetDummyBackendId(TransactionId xid, bool lock_held)
Definition: twophase.c:918
static void MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid, TimestampTz prepared_at, Oid owner, Oid databaseid)
Definition: twophase.c:450
struct GlobalTransactionData GlobalTransactionData
static void save_state_data(const void *data, uint32 len)
Definition: twophase.c:1014
#define TWOPHASE_MAGIC
Definition: twophase.c:966
void FinishPreparedTransaction(const char *gid, bool isCommit)
Definition: twophase.c:1480
#define TwoPhaseFilePath(path, xid)
Definition: twophase.c:944
struct TwoPhaseRecordOnDisk TwoPhaseRecordOnDisk
TransactionId TwoPhaseGetXidByVirtualXID(VirtualTransactionId vxid, bool *have_more)
Definition: twophase.c:870
static void GXactLoadSubxactData(GlobalTransaction gxact, int nsubxacts, TransactionId *children)
Definition: twophase.c:522
void PrepareRedoRemove(TransactionId xid, bool giveWarning)
Definition: twophase.c:2525
Datum pg_prepared_xact(PG_FUNCTION_ARGS)
Definition: twophase.c:729
void EndPrepare(GlobalTransaction gxact)
Definition: twophase.c:1135
static void RemoveTwoPhaseFile(TransactionId xid, bool giveWarning)
Definition: twophase.c:1694
TransactionId PrescanPreparedTransactions(TransactionId **xids_p, int *nxids_p)
Definition: twophase.c:1937
static char * ReadTwoPhaseFile(TransactionId xid, bool missing_ok)
Definition: twophase.c:1280
void StartPrepare(GlobalTransaction gxact)
Definition: twophase.c:1042
static int GetPreparedTransactionList(GlobalTransaction *gxacts)
Definition: twophase.c:684
PGPROC * TwoPhaseGetDummyProc(TransactionId xid, bool lock_held)
Definition: twophase.c:933
void TwoPhaseShmemInit(void)
Definition: twophase.c:256
void PrepareRedoAdd(char *buf, XLogRecPtr start_lsn, XLogRecPtr end_lsn, RepOriginId origin_id)
Definition: twophase.c:2455
static GlobalTransaction TwoPhaseGetGXact(TransactionId xid, bool lock_held)
Definition: twophase.c:818
void StandbyRecoverPreparedTransactions(void)
Definition: twophase.c:2018
static void AtProcExit_Twophase(int code, Datum arg)
Definition: twophase.c:311
static char * ProcessTwoPhaseBuffer(TransactionId xid, XLogRecPtr prepare_start_lsn, bool fromdisk, bool setParent, bool setNextXid)
Definition: twophase.c:2162
static void MarkAsPrepared(GlobalTransaction gxact, bool lock_held)
Definition: twophase.c:548
void PostPrepare_Twophase(void)
Definition: twophase.c:361
xl_xact_prepare TwoPhaseFileHeader
Definition: twophase.c:968
void CheckPointTwoPhase(XLogRecPtr redo_horizon)
Definition: twophase.c:1793
struct StateFileChunk StateFileChunk
bool StandbyTransactionIdIsPrepared(TransactionId xid)
Definition: twophase.c:1452
static void RecreateTwoPhaseFile(TransactionId xid, void *content, int len)
Definition: twophase.c:1713
GlobalTransaction MarkAsPreparing(TransactionId xid, const char *gid, TimestampTz prepared_at, Oid owner, Oid databaseid)
Definition: twophase.c:376
static GlobalTransaction LockGXact(const char *gid, Oid user)
Definition: twophase.c:570
static struct xllist records
struct GlobalTransactionData * GlobalTransaction
Definition: twophase.h:26
const TwoPhaseCallback twophase_postcommit_callbacks[TWOPHASE_RM_MAX_ID+1]
Definition: twophase_rmgr.c:33
const TwoPhaseCallback twophase_recover_callbacks[TWOPHASE_RM_MAX_ID+1]
Definition: twophase_rmgr.c:24
const TwoPhaseCallback twophase_postabort_callbacks[TWOPHASE_RM_MAX_ID+1]
Definition: twophase_rmgr.c:42
#define TWOPHASE_RM_MAX_ID
Definition: twophase_rmgr.h:29
uint8 TwoPhaseRmgrId
Definition: twophase_rmgr.h:19
#define TWOPHASE_RM_END_ID
Definition: twophase_rmgr.h:24
void(* TwoPhaseCallback)(TransactionId xid, uint16 info, void *recdata, uint32 len)
Definition: twophase_rmgr.h:17
static Datum TimestampTzGetDatum(TimestampTz X)
Definition: timestamp.h:52
void AdvanceNextFullTransactionIdPastXid(TransactionId xid)
Definition: varsup.c:277
VariableCache ShmemVariableCache
Definition: varsup.c:34
@ WAIT_EVENT_TWOPHASE_FILE_READ
Definition: wait_event.h:218
@ WAIT_EVENT_TWOPHASE_FILE_WRITE
Definition: wait_event.h:220
@ WAIT_EVENT_TWOPHASE_FILE_SYNC
Definition: wait_event.h:219
static void pgstat_report_wait_start(uint32 wait_event_info)
Definition: wait_event.h:267
static void pgstat_report_wait_end(void)
Definition: wait_event.h:283
#define fstat
Definition: win32_port.h:285
XLogRecPtr XactLogCommitRecord(TimestampTz commit_time, int nsubxacts, TransactionId *subxacts, int nrels, RelFileLocator *rels, int ndroppedstats, xl_xact_stats_item *droppedstats, int nmsgs, SharedInvalidationMessage *msgs, bool relcacheInval, int xactflags, TransactionId twophase_xid, const char *twophase_gid)
Definition: xact.c:5609
int xactGetCommittedChildren(TransactionId **ptr)
Definition: xact.c:5585
int MyXactFlags
Definition: xact.c:135
XLogRecPtr XactLogAbortRecord(TimestampTz abort_time, int nsubxacts, TransactionId *subxacts, int nrels, RelFileLocator *rels, int ndroppedstats, xl_xact_stats_item *droppedstats, int xactflags, TransactionId twophase_xid, const char *twophase_gid)
Definition: xact.c:5781
#define XLOG_XACT_PREPARE
Definition: xact.h:163
#define XACT_FLAGS_ACQUIREDACCESSEXCLUSIVELOCK
Definition: xact.h:108
#define XLOG_XACT_OPMASK
Definition: xact.h:172
#define GIDSIZE
Definition: xact.h:31
XLogRecPtr ProcLastRecPtr
Definition: xlog.c:256
bool RecoveryInProgress(void)
Definition: xlog.c:5939
XLogRecPtr XactLastRecEnd
Definition: xlog.c:257
int wal_segment_size
Definition: xlog.c:146
bool log_checkpoints
Definition: xlog.c:132
void XLogFlush(XLogRecPtr record)
Definition: xlog.c:2516
#define XLOG_INCLUDE_ORIGIN
Definition: xlog.h:150
#define LSN_FORMAT_ARGS(lsn)
Definition: xlogdefs.h:43
#define XLogRecPtrIsInvalid(r)
Definition: xlogdefs.h:29
uint16 RepOriginId
Definition: xlogdefs.h:65
uint64 XLogRecPtr
Definition: xlogdefs.h:21
#define InvalidXLogRecPtr
Definition: xlogdefs.h:28
void XLogRegisterData(char *data, uint32 len)
Definition: xloginsert.c:351
XLogRecPtr XLogInsert(RmgrId rmid, uint8 info)
Definition: xloginsert.c:451
void XLogSetRecordFlags(uint8 flags)
Definition: xloginsert.c:433
void XLogBeginInsert(void)
Definition: xloginsert.c:150
void XLogEnsureRecordSpace(int max_block_id, int ndatas)
Definition: xloginsert.c:176
XLogRecord * XLogReadRecord(XLogReaderState *state, char **errormsg)
Definition: xlogreader.c:422
void XLogReaderFree(XLogReaderState *state)
Definition: xlogreader.c:170
XLogReaderState * XLogReaderAllocate(int wal_segment_size, const char *waldir, XLogReaderRoutine *routine, void *private_data)
Definition: xlogreader.c:108
void XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr)
Definition: xlogreader.c:264
#define XLogRecGetDataLen(decoder)
Definition: xlogreader.h:417
#define XLogRecGetInfo(decoder)
Definition: xlogreader.h:411
#define XLogRecGetRmid(decoder)
Definition: xlogreader.h:412
#define XLogRecGetData(decoder)
Definition: xlogreader.h:416
#define XL_ROUTINE(...)
Definition: xlogreader.h:117
static XLogReaderState * xlogreader
Definition: xlogrecovery.c:189
void wal_segment_close(XLogReaderState *state)
Definition: xlogutils.c:859
void wal_segment_open(XLogReaderState *state, XLogSegNo nextSegNo, TimeLineID *tli_p)
Definition: xlogutils.c:834
int read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen, XLogRecPtr targetRecPtr, char *cur_page)
Definition: xlogutils.c:878
#define InHotStandby
Definition: xlogutils.h:57