PostgreSQL Source Code  git master
snapbuild.h File Reference
#include "access/xlogdefs.h"
#include "utils/snapmgr.h"
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Typedefs

typedef struct SnapBuild SnapBuild
 

Enumerations

enum  SnapBuildState { SNAPBUILD_START = -1, SNAPBUILD_BUILDING_SNAPSHOT = 0, SNAPBUILD_FULL_SNAPSHOT = 1, SNAPBUILD_CONSISTENT = 2 }
 

Functions

void CheckPointSnapBuild (void)
 
SnapBuildAllocateSnapshotBuilder (struct ReorderBuffer *cache, TransactionId xmin_horizon, XLogRecPtr start_lsn, bool need_full_snapshot, XLogRecPtr initial_consistent_point)
 
void FreeSnapshotBuilder (SnapBuild *cache)
 
void SnapBuildSnapDecRefcount (Snapshot snap)
 
Snapshot SnapBuildInitialSnapshot (SnapBuild *builder)
 
const char * SnapBuildExportSnapshot (SnapBuild *snapstate)
 
void SnapBuildClearExportedSnapshot (void)
 
SnapBuildState SnapBuildCurrentState (SnapBuild *snapstate)
 
Snapshot SnapBuildGetOrBuildSnapshot (SnapBuild *builder, TransactionId xid)
 
bool SnapBuildXactNeedsSkip (SnapBuild *snapstate, XLogRecPtr ptr)
 
XLogRecPtr SnapBuildInitialConsistentPoint (SnapBuild *builder)
 
void SnapBuildCommitTxn (SnapBuild *builder, XLogRecPtr lsn, TransactionId xid, int nsubxacts, TransactionId *subxacts)
 
bool SnapBuildProcessChange (SnapBuild *builder, TransactionId xid, XLogRecPtr lsn)
 
void SnapBuildProcessNewCid (SnapBuild *builder, TransactionId xid, XLogRecPtr lsn, struct xl_heap_new_cid *cid)
 
void SnapBuildProcessRunningXacts (SnapBuild *builder, XLogRecPtr lsn, struct xl_running_xacts *running)
 
void SnapBuildSerializationPoint (SnapBuild *builder, XLogRecPtr lsn)
 

Typedef Documentation

◆ SnapBuild

typedef struct SnapBuild SnapBuild

Definition at line 51 of file snapbuild.h.

Enumeration Type Documentation

◆ SnapBuildState

Enumerator
SNAPBUILD_START 
SNAPBUILD_BUILDING_SNAPSHOT 
SNAPBUILD_FULL_SNAPSHOT 
SNAPBUILD_CONSISTENT 

Definition at line 18 of file snapbuild.h.

19 {
20  /*
21  * Initial state, we can't do much yet.
22  */
23  SNAPBUILD_START = -1,
24 
25  /*
26  * Collecting committed transactions, to build the initial catalog
27  * snapshot.
28  */
30 
31  /*
32  * We have collected enough information to decode tuples in transactions
33  * that started after this.
34  *
35  * Once we reached this we start to collect changes. We cannot apply them
36  * yet, because they might be based on transactions that were still
37  * running when FULL_SNAPSHOT was reached.
38  */
40 
41  /*
42  * Found a point after SNAPBUILD_FULL_SNAPSHOT where all transactions that
43  * were running at that point finished. Till we reach that we hold off
44  * calling any commit callbacks.
45  */
SnapBuildState
Definition: snapbuild.h:18

Function Documentation

◆ AllocateSnapshotBuilder()

SnapBuild* AllocateSnapshotBuilder ( struct ReorderBuffer cache,
TransactionId  xmin_horizon,
XLogRecPtr  start_lsn,
bool  need_full_snapshot,
XLogRecPtr  initial_consistent_point 
)

Definition at line 280 of file snapbuild.c.

References ALLOCSET_DEFAULT_SIZES, AllocSetContextCreate, SnapBuild::building_full_snapshot, SnapBuild::committed, SnapBuild::context, CurrentMemoryContext, SnapBuild::includes_all_transactions, SnapBuild::initial_consistent_point, SnapBuild::initial_xmin_horizon, MemoryContextSwitchTo(), palloc0(), SnapBuild::reorder, SNAPBUILD_START, SnapBuild::start_decoding_at, SnapBuild::state, SnapBuild::xcnt, SnapBuild::xcnt_space, and SnapBuild::xip.

Referenced by StartupDecodingContext().

285 {
286  MemoryContext context;
287  MemoryContext oldcontext;
288  SnapBuild *builder;
289 
290  /* allocate memory in own context, to have better accountability */
292  "snapshot builder context",
294  oldcontext = MemoryContextSwitchTo(context);
295 
296  builder = palloc0(sizeof(SnapBuild));
297 
298  builder->state = SNAPBUILD_START;
299  builder->context = context;
300  builder->reorder = reorder;
301  /* Other struct members initialized by zeroing via palloc0 above */
302 
303  builder->committed.xcnt = 0;
304  builder->committed.xcnt_space = 128; /* arbitrary number */
305  builder->committed.xip =
306  palloc0(builder->committed.xcnt_space * sizeof(TransactionId));
307  builder->committed.includes_all_transactions = true;
308 
309  builder->initial_xmin_horizon = xmin_horizon;
310  builder->start_decoding_at = start_lsn;
311  builder->building_full_snapshot = need_full_snapshot;
312  builder->initial_consistent_point = initial_consistent_point;
313 
314  MemoryContextSwitchTo(oldcontext);
315 
316  return builder;
317 }
#define AllocSetContextCreate
Definition: memutils.h:170
uint32 TransactionId
Definition: c.h:587
XLogRecPtr initial_consistent_point
Definition: snapbuild.c:176
bool building_full_snapshot
Definition: snapbuild.c:185
static MemoryContext MemoryContextSwitchTo(MemoryContext context)
Definition: palloc.h:109
size_t xcnt_space
Definition: snapbuild.c:219
size_t xcnt
Definition: snapbuild.c:216
SnapBuildState state
Definition: snapbuild.c:150
#define ALLOCSET_DEFAULT_SIZES
Definition: memutils.h:192
ReorderBuffer * reorder
Definition: snapbuild.c:200
TransactionId initial_xmin_horizon
Definition: snapbuild.c:182
TransactionId * xip
Definition: snapbuild.c:242
bool includes_all_transactions
Definition: snapbuild.c:226
MemoryContext CurrentMemoryContext
Definition: mcxt.c:38
void * palloc0(Size size)
Definition: mcxt.c:981
MemoryContext context
Definition: snapbuild.c:153
struct SnapBuild::@16 committed
XLogRecPtr start_decoding_at
Definition: snapbuild.c:165

◆ CheckPointSnapBuild()

void CheckPointSnapBuild ( void  )

Definition at line 1898 of file snapbuild.c.

References AllocateDir(), dirent::d_name, DEBUG1, elog, ereport, errcode_for_file_access(), errmsg(), FreeDir(), GetRedoRecPtr(), InvalidXLogRecPtr, LOG, lstat, MAXPGPATH, ReadDir(), ReplicationSlotsComputeLogicalRestartLSN(), S_ISREG, snprintf, and stat::st_mode.

Referenced by CheckPointGuts().

1899 {
1900  XLogRecPtr cutoff;
1901  XLogRecPtr redo;
1902  DIR *snap_dir;
1903  struct dirent *snap_de;
1904  char path[MAXPGPATH + 21];
1905 
1906  /*
1907  * We start off with a minimum of the last redo pointer. No new
1908  * replication slot will start before that, so that's a safe upper bound
1909  * for removal.
1910  */
1911  redo = GetRedoRecPtr();
1912 
1913  /* now check for the restart ptrs from existing slots */
1915 
1916  /* don't start earlier than the restart lsn */
1917  if (redo < cutoff)
1918  cutoff = redo;
1919 
1920  snap_dir = AllocateDir("pg_logical/snapshots");
1921  while ((snap_de = ReadDir(snap_dir, "pg_logical/snapshots")) != NULL)
1922  {
1923  uint32 hi;
1924  uint32 lo;
1925  XLogRecPtr lsn;
1926  struct stat statbuf;
1927 
1928  if (strcmp(snap_de->d_name, ".") == 0 ||
1929  strcmp(snap_de->d_name, "..") == 0)
1930  continue;
1931 
1932  snprintf(path, sizeof(path), "pg_logical/snapshots/%s", snap_de->d_name);
1933 
1934  if (lstat(path, &statbuf) == 0 && !S_ISREG(statbuf.st_mode))
1935  {
1936  elog(DEBUG1, "only regular files expected: %s", path);
1937  continue;
1938  }
1939 
1940  /*
1941  * temporary filenames from SnapBuildSerialize() include the LSN and
1942  * everything but are postfixed by .$pid.tmp. We can just remove them
1943  * the same as other files because there can be none that are
1944  * currently being written that are older than cutoff.
1945  *
1946  * We just log a message if a file doesn't fit the pattern, it's
1947  * probably some editors lock/state file or similar...
1948  */
1949  if (sscanf(snap_de->d_name, "%X-%X.snap", &hi, &lo) != 2)
1950  {
1951  ereport(LOG,
1952  (errmsg("could not parse file name \"%s\"", path)));
1953  continue;
1954  }
1955 
1956  lsn = ((uint64) hi) << 32 | lo;
1957 
1958  /* check whether we still need it */
1959  if (lsn < cutoff || cutoff == InvalidXLogRecPtr)
1960  {
1961  elog(DEBUG1, "removing snapbuild snapshot %s", path);
1962 
1963  /*
1964  * It's not particularly harmful, though strange, if we can't
1965  * remove the file here. Don't prevent the checkpoint from
1966  * completing, that'd be a cure worse than the disease.
1967  */
1968  if (unlink(path) < 0)
1969  {
1970  ereport(LOG,
1972  errmsg("could not remove file \"%s\": %m",
1973  path)));
1974  continue;
1975  }
1976  }
1977  }
1978  FreeDir(snap_dir);
1979 }
#define InvalidXLogRecPtr
Definition: xlogdefs.h:28
#define DEBUG1
Definition: elog.h:25
#define LOG
Definition: elog.h:26
Definition: dirent.h:9
Definition: dirent.c:25
#define MAXPGPATH
int errcode_for_file_access(void)
Definition: elog.c:717
XLogRecPtr ReplicationSlotsComputeLogicalRestartLSN(void)
Definition: slot.c:877
unsigned int uint32
Definition: c.h:441
DIR * AllocateDir(const char *dirname)
Definition: fd.c:2615
#define S_ISREG(m)
Definition: win32_port.h:319
#define ereport(elevel,...)
Definition: elog.h:155
uint64 XLogRecPtr
Definition: xlogdefs.h:21
struct dirent * ReadDir(DIR *dir, const char *dirname)
Definition: fd.c:2681
XLogRecPtr GetRedoRecPtr(void)
Definition: xlog.c:8424
#define lstat(path, sb)
Definition: win32_port.h:276
int errmsg(const char *fmt,...)
Definition: elog.c:905
#define elog(elevel,...)
Definition: elog.h:227
char d_name[MAX_PATH]
Definition: dirent.h:15
#define snprintf
Definition: port.h:216
int FreeDir(DIR *dir)
Definition: fd.c:2733

◆ FreeSnapshotBuilder()

void FreeSnapshotBuilder ( SnapBuild cache)

Definition at line 323 of file snapbuild.c.

References SnapBuild::context, MemoryContextDelete(), SnapBuildSnapDecRefcount(), and SnapBuild::snapshot.

Referenced by FreeDecodingContext().

324 {
325  MemoryContext context = builder->context;
326 
327  /* free snapshot explicitly, that contains some error checking */
328  if (builder->snapshot != NULL)
329  {
330  SnapBuildSnapDecRefcount(builder->snapshot);
331  builder->snapshot = NULL;
332  }
333 
334  /* other resources are deallocated via memory context reset */
335  MemoryContextDelete(context);
336 }
void MemoryContextDelete(MemoryContext context)
Definition: mcxt.c:212
void SnapBuildSnapDecRefcount(Snapshot snap)
Definition: snapbuild.c:409

◆ SnapBuildClearExportedSnapshot()

void SnapBuildClearExportedSnapshot ( void  )

Definition at line 674 of file snapbuild.c.

References AbortCurrentTransaction(), CurrentResourceOwner, elog, ERROR, ExportInProgress, IsTransactionState(), and SavedResourceOwnerDuringExport.

Referenced by exec_replication_command().

675 {
676  /* nothing exported, that is the usual case */
677  if (!ExportInProgress)
678  return;
679 
680  if (!IsTransactionState())
681  elog(ERROR, "clearing exported snapshot in wrong transaction state");
682 
683  /* make sure nothing could have ever happened */
685 
688  ExportInProgress = false;
689 }
void AbortCurrentTransaction(void)
Definition: xact.c:3210
ResourceOwner CurrentResourceOwner
Definition: resowner.c:144
static ResourceOwner SavedResourceOwnerDuringExport
Definition: snapbuild.c:250
#define ERROR
Definition: elog.h:45
static bool ExportInProgress
Definition: snapbuild.c:251
bool IsTransactionState(void)
Definition: xact.c:371
#define elog(elevel,...)
Definition: elog.h:227

◆ SnapBuildCommitTxn()

void SnapBuildCommitTxn ( SnapBuild builder,
XLogRecPtr  lsn,
TransactionId  xid,
int  nsubxacts,
TransactionId subxacts 
)

Definition at line 912 of file snapbuild.c.

References Assert, SnapBuild::building_full_snapshot, SnapBuild::committed, DEBUG1, DEBUG2, elog, SnapBuild::includes_all_transactions, SnapBuild::next_phase_at, NormalTransactionIdFollows, SnapBuild::reorder, ReorderBufferSetBaseSnapshot(), ReorderBufferXidHasBaseSnapshot(), ReorderBufferXidHasCatalogChanges(), SNAPBUILD_BUILDING_SNAPSHOT, SNAPBUILD_CONSISTENT, SNAPBUILD_FULL_SNAPSHOT, SNAPBUILD_START, SnapBuildAddCommittedTxn(), SnapBuildBuildSnapshot(), SnapBuildDistributeNewCatalogSnapshot(), SnapBuildSnapDecRefcount(), SnapBuildSnapIncRefcount(), SnapBuild::snapshot, SnapBuild::start_decoding_at, SnapBuild::state, TransactionIdAdvance, TransactionIdFollowsOrEquals(), TransactionIdIsValid, TransactionIdPrecedes(), and SnapBuild::xmax.

Referenced by DecodeCommit().

914 {
915  int nxact;
916 
917  bool needs_snapshot = false;
918  bool needs_timetravel = false;
919  bool sub_needs_timetravel = false;
920 
921  TransactionId xmax = xid;
922 
923  /*
924  * Transactions preceding BUILDING_SNAPSHOT will neither be decoded, nor
925  * will they be part of a snapshot. So we don't need to record anything.
926  */
927  if (builder->state == SNAPBUILD_START ||
928  (builder->state == SNAPBUILD_BUILDING_SNAPSHOT &&
929  TransactionIdPrecedes(xid, builder->next_phase_at)))
930  {
931  /* ensure that only commits after this are getting replayed */
932  if (builder->start_decoding_at <= lsn)
933  builder->start_decoding_at = lsn + 1;
934  return;
935  }
936 
937  if (builder->state < SNAPBUILD_CONSISTENT)
938  {
939  /* ensure that only commits after this are getting replayed */
940  if (builder->start_decoding_at <= lsn)
941  builder->start_decoding_at = lsn + 1;
942 
943  /*
944  * If building an exportable snapshot, force xid to be tracked, even
945  * if the transaction didn't modify the catalog.
946  */
947  if (builder->building_full_snapshot)
948  {
949  needs_timetravel = true;
950  }
951  }
952 
953  for (nxact = 0; nxact < nsubxacts; nxact++)
954  {
955  TransactionId subxid = subxacts[nxact];
956 
957  /*
958  * Add subtransaction to base snapshot if catalog modifying, we don't
959  * distinguish to toplevel transactions there.
960  */
961  if (ReorderBufferXidHasCatalogChanges(builder->reorder, subxid))
962  {
963  sub_needs_timetravel = true;
964  needs_snapshot = true;
965 
966  elog(DEBUG1, "found subtransaction %u:%u with catalog changes",
967  xid, subxid);
968 
969  SnapBuildAddCommittedTxn(builder, subxid);
970 
971  if (NormalTransactionIdFollows(subxid, xmax))
972  xmax = subxid;
973  }
974 
975  /*
976  * If we're forcing timetravel we also need visibility information
977  * about subtransaction, so keep track of subtransaction's state, even
978  * if not catalog modifying. Don't need to distribute a snapshot in
979  * that case.
980  */
981  else if (needs_timetravel)
982  {
983  SnapBuildAddCommittedTxn(builder, subxid);
984  if (NormalTransactionIdFollows(subxid, xmax))
985  xmax = subxid;
986  }
987  }
988 
989  /* if top-level modified catalog, it'll need a snapshot */
990  if (ReorderBufferXidHasCatalogChanges(builder->reorder, xid))
991  {
992  elog(DEBUG2, "found top level transaction %u, with catalog changes",
993  xid);
994  needs_snapshot = true;
995  needs_timetravel = true;
996  SnapBuildAddCommittedTxn(builder, xid);
997  }
998  else if (sub_needs_timetravel)
999  {
1000  /* track toplevel txn as well, subxact alone isn't meaningful */
1001  SnapBuildAddCommittedTxn(builder, xid);
1002  }
1003  else if (needs_timetravel)
1004  {
1005  elog(DEBUG2, "forced transaction %u to do timetravel", xid);
1006 
1007  SnapBuildAddCommittedTxn(builder, xid);
1008  }
1009 
1010  if (!needs_timetravel)
1011  {
1012  /* record that we cannot export a general snapshot anymore */
1013  builder->committed.includes_all_transactions = false;
1014  }
1015 
1016  Assert(!needs_snapshot || needs_timetravel);
1017 
1018  /*
1019  * Adjust xmax of the snapshot builder, we only do that for committed,
1020  * catalog modifying, transactions, everything else isn't interesting for
1021  * us since we'll never look at the respective rows.
1022  */
1023  if (needs_timetravel &&
1024  (!TransactionIdIsValid(builder->xmax) ||
1025  TransactionIdFollowsOrEquals(xmax, builder->xmax)))
1026  {
1027  builder->xmax = xmax;
1028  TransactionIdAdvance(builder->xmax);
1029  }
1030 
1031  /* if there's any reason to build a historic snapshot, do so now */
1032  if (needs_snapshot)
1033  {
1034  /*
1035  * If we haven't built a complete snapshot yet there's no need to hand
1036  * it out, it wouldn't (and couldn't) be used anyway.
1037  */
1038  if (builder->state < SNAPBUILD_FULL_SNAPSHOT)
1039  return;
1040 
1041  /*
1042  * Decrease the snapshot builder's refcount of the old snapshot, note
1043  * that it still will be used if it has been handed out to the
1044  * reorderbuffer earlier.
1045  */
1046  if (builder->snapshot)
1048 
1049  builder->snapshot = SnapBuildBuildSnapshot(builder);
1050 
1051  /* we might need to execute invalidations, add snapshot */
1052  if (!ReorderBufferXidHasBaseSnapshot(builder->reorder, xid))
1053  {
1055  ReorderBufferSetBaseSnapshot(builder->reorder, xid, lsn,
1056  builder->snapshot);
1057  }
1058 
1059  /* refcount of the snapshot builder for the new snapshot */
1061 
1062  /* add a new catalog snapshot to all currently running transactions */
1064  }
1065 }
#define TransactionIdAdvance(dest)
Definition: transam.h:91
bool ReorderBufferXidHasBaseSnapshot(ReorderBuffer *rb, TransactionId xid)
#define DEBUG1
Definition: elog.h:25
static void SnapBuildAddCommittedTxn(SnapBuild *builder, TransactionId xid)
Definition: snapbuild.c:842
uint32 TransactionId
Definition: c.h:587
TransactionId next_phase_at
Definition: snapbuild.c:207
Snapshot snapshot
Definition: snapbuild.c:190
bool building_full_snapshot
Definition: snapbuild.c:185
void ReorderBufferSetBaseSnapshot(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn, Snapshot snap)
bool TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2)
Definition: transam.c:349
SnapBuildState state
Definition: snapbuild.c:150
static void SnapBuildDistributeNewCatalogSnapshot(SnapBuild *builder, XLogRecPtr lsn)
Definition: snapbuild.c:789
#define DEBUG2
Definition: elog.h:24
ReorderBuffer * reorder
Definition: snapbuild.c:200
static Snapshot SnapBuildBuildSnapshot(SnapBuild *builder)
Definition: snapbuild.c:441
bool includes_all_transactions
Definition: snapbuild.c:226
bool ReorderBufferXidHasCatalogChanges(ReorderBuffer *rb, TransactionId xid)
bool TransactionIdPrecedes(TransactionId id1, TransactionId id2)
Definition: transam.c:300
TransactionId xmax
Definition: snapbuild.c:159
#define Assert(condition)
Definition: c.h:804
#define NormalTransactionIdFollows(id1, id2)
Definition: transam.h:152
void SnapBuildSnapDecRefcount(Snapshot snap)
Definition: snapbuild.c:409
struct SnapBuild::@16 committed
#define elog(elevel,...)
Definition: elog.h:227
#define TransactionIdIsValid(xid)
Definition: transam.h:41
static void SnapBuildSnapIncRefcount(Snapshot snap)
Definition: snapbuild.c:397
XLogRecPtr start_decoding_at
Definition: snapbuild.c:165

◆ SnapBuildCurrentState()

SnapBuildState SnapBuildCurrentState ( SnapBuild snapstate)

Definition at line 367 of file snapbuild.c.

References SnapBuild::state.

Referenced by DecodeHeap2Op(), DecodeHeapOp(), DecodeLogicalMsgOp(), DecodePrepare(), DecodeXactOp(), DecodingContextReady(), and ReorderBufferCanStartStreaming().

368 {
369  return builder->state;
370 }

◆ SnapBuildExportSnapshot()

const char* SnapBuildExportSnapshot ( SnapBuild snapstate)

Definition at line 613 of file snapbuild.c.

References CurrentResourceOwner, elog, ereport, errmsg_plural(), ERROR, ExportInProgress, ExportSnapshot(), IsTransactionOrTransactionBlock(), LOG, SnapBuildInitialSnapshot(), StartTransactionCommand(), XACT_REPEATABLE_READ, XactIsoLevel, XactReadOnly, and SnapshotData::xcnt.

Referenced by CreateReplicationSlot().

614 {
615  Snapshot snap;
616  char *snapname;
617 
619  elog(ERROR, "cannot export a snapshot from within a transaction");
620 
622  elog(ERROR, "can only export one snapshot at a time");
623 
625  ExportInProgress = true;
626 
628 
629  /* There doesn't seem to a nice API to set these */
631  XactReadOnly = true;
632 
633  snap = SnapBuildInitialSnapshot(builder);
634 
635  /*
636  * now that we've built a plain snapshot, make it active and use the
637  * normal mechanisms for exporting it
638  */
639  snapname = ExportSnapshot(snap);
640 
641  ereport(LOG,
642  (errmsg_plural("exported logical decoding snapshot: \"%s\" with %u transaction ID",
643  "exported logical decoding snapshot: \"%s\" with %u transaction IDs",
644  snap->xcnt,
645  snapname, snap->xcnt)));
646  return snapname;
647 }
int errmsg_plural(const char *fmt_singular, const char *fmt_plural, unsigned long n,...)
Definition: elog.c:1015
ResourceOwner CurrentResourceOwner
Definition: resowner.c:144
#define XACT_REPEATABLE_READ
Definition: xact.h:38
bool IsTransactionOrTransactionBlock(void)
Definition: xact.c:4701
char * ExportSnapshot(Snapshot snapshot)
Definition: snapmgr.c:1106
#define LOG
Definition: elog.h:26
static ResourceOwner SavedResourceOwnerDuringExport
Definition: snapbuild.c:250
#define ERROR
Definition: elog.h:45
static bool ExportInProgress
Definition: snapbuild.c:251
#define ereport(elevel,...)
Definition: elog.h:155
bool XactReadOnly
Definition: xact.c:78
void StartTransactionCommand(void)
Definition: xact.c:2838
int XactIsoLevel
Definition: xact.c:75
Snapshot SnapBuildInitialSnapshot(SnapBuild *builder)
Definition: snapbuild.c:521
uint32 xcnt
Definition: snapshot.h:169
#define elog(elevel,...)
Definition: elog.h:227

◆ SnapBuildGetOrBuildSnapshot()

Snapshot SnapBuildGetOrBuildSnapshot ( SnapBuild builder,
TransactionId  xid 
)

Definition at line 653 of file snapbuild.c.

References Assert, SNAPBUILD_CONSISTENT, SnapBuildBuildSnapshot(), SnapBuildSnapIncRefcount(), SnapBuild::snapshot, and SnapBuild::state.

Referenced by DecodeLogicalMsgOp().

654 {
655  Assert(builder->state == SNAPBUILD_CONSISTENT);
656 
657  /* only build a new snapshot if we don't have a prebuilt one */
658  if (builder->snapshot == NULL)
659  {
660  builder->snapshot = SnapBuildBuildSnapshot(builder);
661  /* increase refcount for the snapshot builder */
663  }
664 
665  return builder->snapshot;
666 }
Snapshot snapshot
Definition: snapbuild.c:190
SnapBuildState state
Definition: snapbuild.c:150
static Snapshot SnapBuildBuildSnapshot(SnapBuild *builder)
Definition: snapbuild.c:441
#define Assert(condition)
Definition: c.h:804
static void SnapBuildSnapIncRefcount(Snapshot snap)
Definition: snapbuild.c:397

◆ SnapBuildInitialConsistentPoint()

XLogRecPtr SnapBuildInitialConsistentPoint ( SnapBuild builder)

Definition at line 376 of file snapbuild.c.

References SnapBuild::initial_consistent_point.

Referenced by DecodeCommit().

377 {
378  return builder->initial_consistent_point;
379 }
XLogRecPtr initial_consistent_point
Definition: snapbuild.c:176

◆ SnapBuildInitialSnapshot()

Snapshot SnapBuildInitialSnapshot ( SnapBuild builder)

Definition at line 521 of file snapbuild.c.

References Assert, SnapBuild::committed, elog, ereport, errcode(), errmsg(), ERROR, FirstSnapshotSet, GetMaxSnapshotXidCount(), GetOldestSafeDecodingTransactionId(), SnapBuild::includes_all_transactions, LW_SHARED, LWLockAcquire(), LWLockRelease(), MyProc, NormalTransactionIdPrecedes, palloc(), SNAPBUILD_CONSISTENT, SnapBuildBuildSnapshot(), SNAPSHOT_MVCC, SnapshotData::snapshot_type, SnapBuild::state, test(), TransactionIdAdvance, TransactionIdIsValid, TransactionIdPrecedesOrEquals(), XACT_REPEATABLE_READ, XactIsoLevel, SnapshotData::xcnt, xidComparator(), SnapshotData::xip, SnapshotData::xmax, PGPROC::xmin, and SnapshotData::xmin.

Referenced by CreateReplicationSlot(), and SnapBuildExportSnapshot().

522 {
523  Snapshot snap;
524  TransactionId xid;
525  TransactionId *newxip;
526  int newxcnt = 0;
527 
530 
531  if (builder->state != SNAPBUILD_CONSISTENT)
532  elog(ERROR, "cannot build an initial slot snapshot before reaching a consistent state");
533 
534  if (!builder->committed.includes_all_transactions)
535  elog(ERROR, "cannot build an initial slot snapshot, not all transactions are monitored anymore");
536 
537  /* so we don't overwrite the existing value */
539  elog(ERROR, "cannot build an initial slot snapshot when MyProc->xmin already is valid");
540 
541  snap = SnapBuildBuildSnapshot(builder);
542 
543  /*
544  * We know that snap->xmin is alive, enforced by the logical xmin
545  * mechanism. Due to that we can do this without locks, we're only
546  * changing our own value.
547  */
548 #ifdef USE_ASSERT_CHECKING
549  {
550  TransactionId safeXid;
551 
552  LWLockAcquire(ProcArrayLock, LW_SHARED);
553  safeXid = GetOldestSafeDecodingTransactionId(false);
554  LWLockRelease(ProcArrayLock);
555 
556  Assert(TransactionIdPrecedesOrEquals(safeXid, snap->xmin));
557  }
558 #endif
559 
560  MyProc->xmin = snap->xmin;
561 
562  /* allocate in transaction context */
563  newxip = (TransactionId *)
565 
566  /*
567  * snapbuild.c builds transactions in an "inverted" manner, which means it
568  * stores committed transactions in ->xip, not ones in progress. Build a
569  * classical snapshot by marking all non-committed transactions as
570  * in-progress. This can be expensive.
571  */
572  for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);)
573  {
574  void *test;
575 
576  /*
577  * Check whether transaction committed using the decoding snapshot
578  * meaning of ->xip.
579  */
580  test = bsearch(&xid, snap->xip, snap->xcnt,
581  sizeof(TransactionId), xidComparator);
582 
583  if (test == NULL)
584  {
585  if (newxcnt >= GetMaxSnapshotXidCount())
586  ereport(ERROR,
587  (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
588  errmsg("initial slot snapshot too large")));
589 
590  newxip[newxcnt++] = xid;
591  }
592 
594  }
595 
596  /* adjust remaining snapshot fields as needed */
598  snap->xcnt = newxcnt;
599  snap->xip = newxip;
600 
601  return snap;
602 }
#define TransactionIdAdvance(dest)
Definition: transam.h:91
TransactionId GetOldestSafeDecodingTransactionId(bool catalogOnly)
Definition: procarray.c:2876
static void test(void)
uint32 TransactionId
Definition: c.h:587
PGPROC * MyProc
Definition: proc.c:68
#define XACT_REPEATABLE_READ
Definition: xact.h:38
int errcode(int sqlerrcode)
Definition: elog.c:694
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1808
SnapBuildState state
Definition: snapbuild.c:150
bool TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2)
Definition: transam.c:319
#define ERROR
Definition: elog.h:45
bool FirstSnapshotSet
Definition: snapmgr.c:149
TransactionId xmin
Definition: proc.h:138
static Snapshot SnapBuildBuildSnapshot(SnapBuild *builder)
Definition: snapbuild.c:441
bool includes_all_transactions
Definition: snapbuild.c:226
SnapshotType snapshot_type
Definition: snapshot.h:144
TransactionId xmax
Definition: snapshot.h:158
TransactionId xmin
Definition: snapshot.h:157
TransactionId * xip
Definition: snapshot.h:168
#define ereport(elevel,...)
Definition: elog.h:155
int GetMaxSnapshotXidCount(void)
Definition: procarray.c:1998
#define Assert(condition)
Definition: c.h:804
int XactIsoLevel
Definition: xact.c:75
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1206
#define NormalTransactionIdPrecedes(id1, id2)
Definition: transam.h:147
struct SnapBuild::@16 committed
uint32 xcnt
Definition: snapshot.h:169
void * palloc(Size size)
Definition: mcxt.c:950
int errmsg(const char *fmt,...)
Definition: elog.c:905
#define elog(elevel,...)
Definition: elog.h:227
#define TransactionIdIsValid(xid)
Definition: transam.h:41
int xidComparator(const void *arg1, const void *arg2)
Definition: xid.c:136

◆ SnapBuildProcessChange()

bool SnapBuildProcessChange ( SnapBuild builder,
TransactionId  xid,
XLogRecPtr  lsn 
)

Definition at line 697 of file snapbuild.c.

References SnapBuild::next_phase_at, SnapBuild::reorder, ReorderBufferSetBaseSnapshot(), ReorderBufferXidHasBaseSnapshot(), SNAPBUILD_CONSISTENT, SNAPBUILD_FULL_SNAPSHOT, SnapBuildBuildSnapshot(), SnapBuildSnapIncRefcount(), SnapBuild::snapshot, SnapBuild::state, and TransactionIdPrecedes().

Referenced by DecodeHeap2Op(), DecodeHeapOp(), and DecodeLogicalMsgOp().

698 {
699  /*
700  * We can't handle data in transactions if we haven't built a snapshot
701  * yet, so don't store them.
702  */
703  if (builder->state < SNAPBUILD_FULL_SNAPSHOT)
704  return false;
705 
706  /*
707  * No point in keeping track of changes in transactions that we don't have
708  * enough information about to decode. This means that they started before
709  * we got into the SNAPBUILD_FULL_SNAPSHOT state.
710  */
711  if (builder->state < SNAPBUILD_CONSISTENT &&
712  TransactionIdPrecedes(xid, builder->next_phase_at))
713  return false;
714 
715  /*
716  * If the reorderbuffer doesn't yet have a snapshot, add one now, it will
717  * be needed to decode the change we're currently processing.
718  */
719  if (!ReorderBufferXidHasBaseSnapshot(builder->reorder, xid))
720  {
721  /* only build a new snapshot if we don't have a prebuilt one */
722  if (builder->snapshot == NULL)
723  {
724  builder->snapshot = SnapBuildBuildSnapshot(builder);
725  /* increase refcount for the snapshot builder */
727  }
728 
729  /*
730  * Increase refcount for the transaction we're handing the snapshot
731  * out to.
732  */
734  ReorderBufferSetBaseSnapshot(builder->reorder, xid, lsn,
735  builder->snapshot);
736  }
737 
738  return true;
739 }
bool ReorderBufferXidHasBaseSnapshot(ReorderBuffer *rb, TransactionId xid)
TransactionId next_phase_at
Definition: snapbuild.c:207
Snapshot snapshot
Definition: snapbuild.c:190
void ReorderBufferSetBaseSnapshot(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn, Snapshot snap)
SnapBuildState state
Definition: snapbuild.c:150
ReorderBuffer * reorder
Definition: snapbuild.c:200
static Snapshot SnapBuildBuildSnapshot(SnapBuild *builder)
Definition: snapbuild.c:441
bool TransactionIdPrecedes(TransactionId id1, TransactionId id2)
Definition: transam.c:300
static void SnapBuildSnapIncRefcount(Snapshot snap)
Definition: snapbuild.c:397

◆ SnapBuildProcessNewCid()

void SnapBuildProcessNewCid ( SnapBuild builder,
TransactionId  xid,
XLogRecPtr  lsn,
struct xl_heap_new_cid cid 
)

Definition at line 747 of file snapbuild.c.

References xl_heap_new_cid::cmax, xl_heap_new_cid::cmin, xl_heap_new_cid::combocid, elog, ERROR, InvalidCommandId, Max, SnapBuild::reorder, ReorderBufferAddNewCommandId(), ReorderBufferAddNewTupleCids(), ReorderBufferXidSetCatalogChanges(), xl_heap_new_cid::target_node, xl_heap_new_cid::target_tid, and xl_heap_new_cid::top_xid.

Referenced by DecodeHeap2Op().

749 {
750  CommandId cid;
751 
752  /*
753  * we only log new_cid's if a catalog tuple was modified, so mark the
754  * transaction as containing catalog modifications
755  */
756  ReorderBufferXidSetCatalogChanges(builder->reorder, xid, lsn);
757 
758  ReorderBufferAddNewTupleCids(builder->reorder, xlrec->top_xid, lsn,
759  xlrec->target_node, xlrec->target_tid,
760  xlrec->cmin, xlrec->cmax,
761  xlrec->combocid);
762 
763  /* figure out new command id */
764  if (xlrec->cmin != InvalidCommandId &&
765  xlrec->cmax != InvalidCommandId)
766  cid = Max(xlrec->cmin, xlrec->cmax);
767  else if (xlrec->cmax != InvalidCommandId)
768  cid = xlrec->cmax;
769  else if (xlrec->cmin != InvalidCommandId)
770  cid = xlrec->cmin;
771  else
772  {
773  cid = InvalidCommandId; /* silence compiler */
774  elog(ERROR, "xl_heap_new_cid record without a valid CommandId");
775  }
776 
777  ReorderBufferAddNewCommandId(builder->reorder, xid, lsn, cid + 1);
778 }
uint32 CommandId
Definition: c.h:601
void ReorderBufferAddNewTupleCids(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn, RelFileNode node, ItemPointerData tid, CommandId cmin, CommandId cmax, CommandId combocid)
#define ERROR
Definition: elog.h:45
ReorderBuffer * reorder
Definition: snapbuild.c:200
#define InvalidCommandId
Definition: c.h:604
#define Max(x, y)
Definition: c.h:980
#define elog(elevel,...)
Definition: elog.h:227
void ReorderBufferXidSetCatalogChanges(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn)
void ReorderBufferAddNewCommandId(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn, CommandId cid)

◆ SnapBuildProcessRunningXacts()

void SnapBuildProcessRunningXacts ( SnapBuild builder,
XLogRecPtr  lsn,
struct xl_running_xacts running 
)

Definition at line 1079 of file snapbuild.c.

References ReorderBuffer::current_restart_decoding_lsn, DEBUG3, elog, InvalidTransactionId, InvalidXLogRecPtr, SnapBuild::last_serialized_snapshot, LogicalIncreaseRestartDecodingForSlot(), LogicalIncreaseXminForSlot(), xl_running_xacts::oldestRunningXid, SnapBuild::reorder, ReorderBufferGetOldestTXN(), ReorderBufferGetOldestXmin(), ReorderBufferTXN::restart_decoding_lsn, SNAPBUILD_CONSISTENT, SnapBuildFindSnapshot(), SnapBuildPurgeCommittedTxn(), SnapBuildSerialize(), SnapBuild::state, SnapBuild::xmax, and SnapBuild::xmin.

Referenced by DecodeStandbyOp().

1080 {
1081  ReorderBufferTXN *txn;
1082  TransactionId xmin;
1083 
1084  /*
1085  * If we're not consistent yet, inspect the record to see whether it
1086  * allows to get closer to being consistent. If we are consistent, dump
1087  * our snapshot so others or we, after a restart, can use it.
1088  */
1089  if (builder->state < SNAPBUILD_CONSISTENT)
1090  {
1091  /* returns false if there's no point in performing cleanup just yet */
1092  if (!SnapBuildFindSnapshot(builder, lsn, running))
1093  return;
1094  }
1095  else
1096  SnapBuildSerialize(builder, lsn);
1097 
1098  /*
1099  * Update range of interesting xids based on the running xacts
1100  * information. We don't increase ->xmax using it, because once we are in
1101  * a consistent state we can do that ourselves and much more efficiently
1102  * so, because we only need to do it for catalog transactions since we
1103  * only ever look at those.
1104  *
1105  * NB: We only increase xmax when a catalog modifying transaction commits
1106  * (see SnapBuildCommitTxn). Because of this, xmax can be lower than
1107  * xmin, which looks odd but is correct and actually more efficient, since
1108  * we hit fast paths in heapam_visibility.c.
1109  */
1110  builder->xmin = running->oldestRunningXid;
1111 
1112  /* Remove transactions we don't need to keep track off anymore */
1113  SnapBuildPurgeCommittedTxn(builder);
1114 
1115  /*
1116  * Advance the xmin limit for the current replication slot, to allow
1117  * vacuum to clean up the tuples this slot has been protecting.
1118  *
1119  * The reorderbuffer might have an xmin among the currently running
1120  * snapshots; use it if so. If not, we need only consider the snapshots
1121  * we'll produce later, which can't be less than the oldest running xid in
1122  * the record we're reading now.
1123  */
1124  xmin = ReorderBufferGetOldestXmin(builder->reorder);
1125  if (xmin == InvalidTransactionId)
1126  xmin = running->oldestRunningXid;
1127  elog(DEBUG3, "xmin: %u, xmax: %u, oldest running: %u, oldest xmin: %u",
1128  builder->xmin, builder->xmax, running->oldestRunningXid, xmin);
1129  LogicalIncreaseXminForSlot(lsn, xmin);
1130 
1131  /*
1132  * Also tell the slot where we can restart decoding from. We don't want to
1133  * do that after every commit because changing that implies an fsync of
1134  * the logical slot's state file, so we only do it every time we see a
1135  * running xacts record.
1136  *
1137  * Do so by looking for the oldest in progress transaction (determined by
1138  * the first LSN of any of its relevant records). Every transaction
1139  * remembers the last location we stored the snapshot to disk before its
1140  * beginning. That point is where we can restart from.
1141  */
1142 
1143  /*
1144  * Can't know about a serialized snapshot's location if we're not
1145  * consistent.
1146  */
1147  if (builder->state < SNAPBUILD_CONSISTENT)
1148  return;
1149 
1150  txn = ReorderBufferGetOldestTXN(builder->reorder);
1151 
1152  /*
1153  * oldest ongoing txn might have started when we didn't yet serialize
1154  * anything because we hadn't reached a consistent state yet.
1155  */
1156  if (txn != NULL && txn->restart_decoding_lsn != InvalidXLogRecPtr)
1158 
1159  /*
1160  * No in-progress transaction, can reuse the last serialized snapshot if
1161  * we have one.
1162  */
1163  else if (txn == NULL &&
1167  builder->last_serialized_snapshot);
1168 }
#define InvalidXLogRecPtr
Definition: xlogdefs.h:28
uint32 TransactionId
Definition: c.h:587
#define DEBUG3
Definition: elog.h:23
void LogicalIncreaseRestartDecodingForSlot(XLogRecPtr current_lsn, XLogRecPtr restart_lsn)
Definition: logical.c:1591
XLogRecPtr current_restart_decoding_lsn
static bool SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *running)
Definition: snapbuild.c:1181
SnapBuildState state
Definition: snapbuild.c:150
static void SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
Definition: snapbuild.c:1469
ReorderBuffer * reorder
Definition: snapbuild.c:200
#define InvalidTransactionId
Definition: transam.h:31
XLogRecPtr last_serialized_snapshot
Definition: snapbuild.c:195
TransactionId xmax
Definition: snapbuild.c:159
TransactionId ReorderBufferGetOldestXmin(ReorderBuffer *rb)
ReorderBufferTXN * ReorderBufferGetOldestTXN(ReorderBuffer *rb)
void LogicalIncreaseXminForSlot(XLogRecPtr current_lsn, TransactionId xmin)
Definition: logical.c:1534
TransactionId xmin
Definition: snapbuild.c:156
#define elog(elevel,...)
Definition: elog.h:227
XLogRecPtr restart_decoding_lsn
TransactionId oldestRunningXid
Definition: standbydefs.h:53
static void SnapBuildPurgeCommittedTxn(SnapBuild *builder)
Definition: snapbuild.c:871

◆ SnapBuildSerializationPoint()

void SnapBuildSerializationPoint ( SnapBuild builder,
XLogRecPtr  lsn 
)

Definition at line 1456 of file snapbuild.c.

References SNAPBUILD_CONSISTENT, SnapBuildRestore(), SnapBuildSerialize(), and SnapBuild::state.

Referenced by DecodeXLogOp().

1457 {
1458  if (builder->state < SNAPBUILD_CONSISTENT)
1459  SnapBuildRestore(builder, lsn);
1460  else
1461  SnapBuildSerialize(builder, lsn);
1462 }
static bool SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
Definition: snapbuild.c:1681
SnapBuildState state
Definition: snapbuild.c:150
static void SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
Definition: snapbuild.c:1469

◆ SnapBuildSnapDecRefcount()

void SnapBuildSnapDecRefcount ( Snapshot  snap)

Definition at line 409 of file snapbuild.c.

References SnapshotData::active_count, Assert, SnapshotData::copied, SnapshotData::curcid, elog, ERROR, FirstCommandId, SnapshotData::regd_count, SnapBuildFreeSnapshot(), SNAPSHOT_HISTORIC_MVCC, SnapshotData::snapshot_type, SnapshotData::suboverflowed, and SnapshotData::takenDuringRecovery.

Referenced by FreeSnapshotBuilder(), ReorderBufferCleanupTXN(), ReorderBufferFreeSnap(), ReorderBufferTransferSnapToParent(), SnapBuildCommitTxn(), and SnapBuildRestore().

410 {
411  /* make sure we don't get passed an external snapshot */
413 
414  /* make sure nobody modified our snapshot */
415  Assert(snap->curcid == FirstCommandId);
416  Assert(!snap->suboverflowed);
417  Assert(!snap->takenDuringRecovery);
418 
419  Assert(snap->regd_count == 0);
420 
421  Assert(snap->active_count > 0);
422 
423  /* slightly more likely, so it's checked even without casserts */
424  if (snap->copied)
425  elog(ERROR, "cannot free a copied snapshot");
426 
427  snap->active_count--;
428  if (snap->active_count == 0)
429  SnapBuildFreeSnapshot(snap);
430 }
bool copied
Definition: snapshot.h:185
bool suboverflowed
Definition: snapshot.h:182
uint32 regd_count
Definition: snapshot.h:205
#define FirstCommandId
Definition: c.h:603
#define ERROR
Definition: elog.h:45
static void SnapBuildFreeSnapshot(Snapshot snap)
Definition: snapbuild.c:342
SnapshotType snapshot_type
Definition: snapshot.h:144
CommandId curcid
Definition: snapshot.h:187
#define Assert(condition)
Definition: c.h:804
bool takenDuringRecovery
Definition: snapshot.h:184
#define elog(elevel,...)
Definition: elog.h:227
uint32 active_count
Definition: snapshot.h:204

◆ SnapBuildXactNeedsSkip()

bool SnapBuildXactNeedsSkip ( SnapBuild snapstate,
XLogRecPtr  ptr 
)

Definition at line 385 of file snapbuild.c.

References SnapBuild::start_decoding_at.

Referenced by DecodeLogicalMsgOp(), DecodeTXNNeedSkip(), and ReorderBufferCanStartStreaming().

386 {
387  return ptr < builder->start_decoding_at;
388 }