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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 two_phase_at)
 
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 SnapBuildGetTwoPhaseAt (SnapBuild *builder)
 
void SnapBuildSetTwoPhaseAt (SnapBuild *builder, XLogRecPtr ptr)
 
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  two_phase_at 
)

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_xmin_horizon, MemoryContextSwitchTo(), palloc0(), SnapBuild::reorder, SNAPBUILD_START, SnapBuild::start_decoding_at, SnapBuild::state, SnapBuild::two_phase_at, 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->two_phase_at = two_phase_at;
313 
314  MemoryContextSwitchTo(oldcontext);
315 
316  return builder;
317 }
#define AllocSetContextCreate
Definition: memutils.h:173
uint32 TransactionId
Definition: c.h:587
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:195
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:42
XLogRecPtr two_phase_at
Definition: snapbuild.c:176
void * palloc0(Size size)
Definition: mcxt.c:1093
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 1907 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().

1908 {
1909  XLogRecPtr cutoff;
1910  XLogRecPtr redo;
1911  DIR *snap_dir;
1912  struct dirent *snap_de;
1913  char path[MAXPGPATH + 21];
1914 
1915  /*
1916  * We start off with a minimum of the last redo pointer. No new
1917  * replication slot will start before that, so that's a safe upper bound
1918  * for removal.
1919  */
1920  redo = GetRedoRecPtr();
1921 
1922  /* now check for the restart ptrs from existing slots */
1924 
1925  /* don't start earlier than the restart lsn */
1926  if (redo < cutoff)
1927  cutoff = redo;
1928 
1929  snap_dir = AllocateDir("pg_logical/snapshots");
1930  while ((snap_de = ReadDir(snap_dir, "pg_logical/snapshots")) != NULL)
1931  {
1932  uint32 hi;
1933  uint32 lo;
1934  XLogRecPtr lsn;
1935  struct stat statbuf;
1936 
1937  if (strcmp(snap_de->d_name, ".") == 0 ||
1938  strcmp(snap_de->d_name, "..") == 0)
1939  continue;
1940 
1941  snprintf(path, sizeof(path), "pg_logical/snapshots/%s", snap_de->d_name);
1942 
1943  if (lstat(path, &statbuf) == 0 && !S_ISREG(statbuf.st_mode))
1944  {
1945  elog(DEBUG1, "only regular files expected: %s", path);
1946  continue;
1947  }
1948 
1949  /*
1950  * temporary filenames from SnapBuildSerialize() include the LSN and
1951  * everything but are postfixed by .$pid.tmp. We can just remove them
1952  * the same as other files because there can be none that are
1953  * currently being written that are older than cutoff.
1954  *
1955  * We just log a message if a file doesn't fit the pattern, it's
1956  * probably some editors lock/state file or similar...
1957  */
1958  if (sscanf(snap_de->d_name, "%X-%X.snap", &hi, &lo) != 2)
1959  {
1960  ereport(LOG,
1961  (errmsg("could not parse file name \"%s\"", path)));
1962  continue;
1963  }
1964 
1965  lsn = ((uint64) hi) << 32 | lo;
1966 
1967  /* check whether we still need it */
1968  if (lsn < cutoff || cutoff == InvalidXLogRecPtr)
1969  {
1970  elog(DEBUG1, "removing snapbuild snapshot %s", path);
1971 
1972  /*
1973  * It's not particularly harmful, though strange, if we can't
1974  * remove the file here. Don't prevent the checkpoint from
1975  * completing, that'd be a cure worse than the disease.
1976  */
1977  if (unlink(path) < 0)
1978  {
1979  ereport(LOG,
1981  errmsg("could not remove file \"%s\": %m",
1982  path)));
1983  continue;
1984  }
1985  }
1986  }
1987  FreeDir(snap_dir);
1988 }
#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:721
XLogRecPtr ReplicationSlotsComputeLogicalRestartLSN(void)
Definition: slot.c:860
unsigned int uint32
Definition: c.h:441
DIR * AllocateDir(const char *dirname)
Definition: fd.c:2720
#define S_ISREG(m)
Definition: win32_port.h:319
#define ereport(elevel,...)
Definition: elog.h:157
uint64 XLogRecPtr
Definition: xlogdefs.h:21
struct dirent * ReadDir(DIR *dir, const char *dirname)
Definition: fd.c:2786
XLogRecPtr GetRedoRecPtr(void)
Definition: xlog.c:8512
#define lstat(path, sb)
Definition: win32_port.h:276
int errmsg(const char *fmt,...)
Definition: elog.c:909
#define elog(elevel,...)
Definition: elog.h:232
char d_name[MAX_PATH]
Definition: dirent.h:15
#define snprintf
Definition: port.h:216
int FreeDir(DIR *dir)
Definition: fd.c:2838

◆ 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:218
void SnapBuildSnapDecRefcount(Snapshot snap)
Definition: snapbuild.c:418

◆ SnapBuildClearExportedSnapshot()

void SnapBuildClearExportedSnapshot ( void  )

Definition at line 683 of file snapbuild.c.

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

Referenced by exec_replication_command().

684 {
685  /* nothing exported, that is the usual case */
686  if (!ExportInProgress)
687  return;
688 
689  if (!IsTransactionState())
690  elog(ERROR, "clearing exported snapshot in wrong transaction state");
691 
692  /* make sure nothing could have ever happened */
694 
697  ExportInProgress = false;
698 }
void AbortCurrentTransaction(void)
Definition: xact.c:3220
ResourceOwner CurrentResourceOwner
Definition: resowner.c:146
static ResourceOwner SavedResourceOwnerDuringExport
Definition: snapbuild.c:250
#define ERROR
Definition: elog.h:46
static bool ExportInProgress
Definition: snapbuild.c:251
bool IsTransactionState(void)
Definition: xact.c:371
#define elog(elevel,...)
Definition: elog.h:232

◆ SnapBuildCommitTxn()

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

Definition at line 921 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().

923 {
924  int nxact;
925 
926  bool needs_snapshot = false;
927  bool needs_timetravel = false;
928  bool sub_needs_timetravel = false;
929 
930  TransactionId xmax = xid;
931 
932  /*
933  * Transactions preceding BUILDING_SNAPSHOT will neither be decoded, nor
934  * will they be part of a snapshot. So we don't need to record anything.
935  */
936  if (builder->state == SNAPBUILD_START ||
937  (builder->state == SNAPBUILD_BUILDING_SNAPSHOT &&
938  TransactionIdPrecedes(xid, builder->next_phase_at)))
939  {
940  /* ensure that only commits after this are getting replayed */
941  if (builder->start_decoding_at <= lsn)
942  builder->start_decoding_at = lsn + 1;
943  return;
944  }
945 
946  if (builder->state < SNAPBUILD_CONSISTENT)
947  {
948  /* ensure that only commits after this are getting replayed */
949  if (builder->start_decoding_at <= lsn)
950  builder->start_decoding_at = lsn + 1;
951 
952  /*
953  * If building an exportable snapshot, force xid to be tracked, even
954  * if the transaction didn't modify the catalog.
955  */
956  if (builder->building_full_snapshot)
957  {
958  needs_timetravel = true;
959  }
960  }
961 
962  for (nxact = 0; nxact < nsubxacts; nxact++)
963  {
964  TransactionId subxid = subxacts[nxact];
965 
966  /*
967  * Add subtransaction to base snapshot if catalog modifying, we don't
968  * distinguish to toplevel transactions there.
969  */
970  if (ReorderBufferXidHasCatalogChanges(builder->reorder, subxid))
971  {
972  sub_needs_timetravel = true;
973  needs_snapshot = true;
974 
975  elog(DEBUG1, "found subtransaction %u:%u with catalog changes",
976  xid, subxid);
977 
978  SnapBuildAddCommittedTxn(builder, subxid);
979 
980  if (NormalTransactionIdFollows(subxid, xmax))
981  xmax = subxid;
982  }
983 
984  /*
985  * If we're forcing timetravel we also need visibility information
986  * about subtransaction, so keep track of subtransaction's state, even
987  * if not catalog modifying. Don't need to distribute a snapshot in
988  * that case.
989  */
990  else if (needs_timetravel)
991  {
992  SnapBuildAddCommittedTxn(builder, subxid);
993  if (NormalTransactionIdFollows(subxid, xmax))
994  xmax = subxid;
995  }
996  }
997 
998  /* if top-level modified catalog, it'll need a snapshot */
999  if (ReorderBufferXidHasCatalogChanges(builder->reorder, xid))
1000  {
1001  elog(DEBUG2, "found top level transaction %u, with catalog changes",
1002  xid);
1003  needs_snapshot = true;
1004  needs_timetravel = true;
1005  SnapBuildAddCommittedTxn(builder, xid);
1006  }
1007  else if (sub_needs_timetravel)
1008  {
1009  /* track toplevel txn as well, subxact alone isn't meaningful */
1010  SnapBuildAddCommittedTxn(builder, xid);
1011  }
1012  else if (needs_timetravel)
1013  {
1014  elog(DEBUG2, "forced transaction %u to do timetravel", xid);
1015 
1016  SnapBuildAddCommittedTxn(builder, xid);
1017  }
1018 
1019  if (!needs_timetravel)
1020  {
1021  /* record that we cannot export a general snapshot anymore */
1022  builder->committed.includes_all_transactions = false;
1023  }
1024 
1025  Assert(!needs_snapshot || needs_timetravel);
1026 
1027  /*
1028  * Adjust xmax of the snapshot builder, we only do that for committed,
1029  * catalog modifying, transactions, everything else isn't interesting for
1030  * us since we'll never look at the respective rows.
1031  */
1032  if (needs_timetravel &&
1033  (!TransactionIdIsValid(builder->xmax) ||
1034  TransactionIdFollowsOrEquals(xmax, builder->xmax)))
1035  {
1036  builder->xmax = xmax;
1037  TransactionIdAdvance(builder->xmax);
1038  }
1039 
1040  /* if there's any reason to build a historic snapshot, do so now */
1041  if (needs_snapshot)
1042  {
1043  /*
1044  * If we haven't built a complete snapshot yet there's no need to hand
1045  * it out, it wouldn't (and couldn't) be used anyway.
1046  */
1047  if (builder->state < SNAPBUILD_FULL_SNAPSHOT)
1048  return;
1049 
1050  /*
1051  * Decrease the snapshot builder's refcount of the old snapshot, note
1052  * that it still will be used if it has been handed out to the
1053  * reorderbuffer earlier.
1054  */
1055  if (builder->snapshot)
1057 
1058  builder->snapshot = SnapBuildBuildSnapshot(builder);
1059 
1060  /* we might need to execute invalidations, add snapshot */
1061  if (!ReorderBufferXidHasBaseSnapshot(builder->reorder, xid))
1062  {
1064  ReorderBufferSetBaseSnapshot(builder->reorder, xid, lsn,
1065  builder->snapshot);
1066  }
1067 
1068  /* refcount of the snapshot builder for the new snapshot */
1070 
1071  /* add a new catalog snapshot to all currently running transactions */
1073  }
1074 }
#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:851
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:798
#define DEBUG2
Definition: elog.h:24
ReorderBuffer * reorder
Definition: snapbuild.c:200
static Snapshot SnapBuildBuildSnapshot(SnapBuild *builder)
Definition: snapbuild.c:450
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:418
struct SnapBuild::@16 committed
#define elog(elevel,...)
Definition: elog.h:232
#define TransactionIdIsValid(xid)
Definition: transam.h:41
static void SnapBuildSnapIncRefcount(Snapshot snap)
Definition: snapbuild.c:406
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 622 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().

623 {
624  Snapshot snap;
625  char *snapname;
626 
628  elog(ERROR, "cannot export a snapshot from within a transaction");
629 
631  elog(ERROR, "can only export one snapshot at a time");
632 
634  ExportInProgress = true;
635 
637 
638  /* There doesn't seem to a nice API to set these */
640  XactReadOnly = true;
641 
642  snap = SnapBuildInitialSnapshot(builder);
643 
644  /*
645  * now that we've built a plain snapshot, make it active and use the
646  * normal mechanisms for exporting it
647  */
648  snapname = ExportSnapshot(snap);
649 
650  ereport(LOG,
651  (errmsg_plural("exported logical decoding snapshot: \"%s\" with %u transaction ID",
652  "exported logical decoding snapshot: \"%s\" with %u transaction IDs",
653  snap->xcnt,
654  snapname, snap->xcnt)));
655  return snapname;
656 }
int errmsg_plural(const char *fmt_singular, const char *fmt_plural, unsigned long n,...)
Definition: elog.c:1019
ResourceOwner CurrentResourceOwner
Definition: resowner.c:146
#define XACT_REPEATABLE_READ
Definition: xact.h:38
bool IsTransactionOrTransactionBlock(void)
Definition: xact.c:4711
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:46
static bool ExportInProgress
Definition: snapbuild.c:251
#define ereport(elevel,...)
Definition: elog.h:157
bool XactReadOnly
Definition: xact.c:78
void StartTransactionCommand(void)
Definition: xact.c:2848
int XactIsoLevel
Definition: xact.c:75
Snapshot SnapBuildInitialSnapshot(SnapBuild *builder)
Definition: snapbuild.c:530
uint32 xcnt
Definition: snapshot.h:169
#define elog(elevel,...)
Definition: elog.h:232

◆ SnapBuildGetOrBuildSnapshot()

Snapshot SnapBuildGetOrBuildSnapshot ( SnapBuild builder,
TransactionId  xid 
)

Definition at line 662 of file snapbuild.c.

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

Referenced by DecodeLogicalMsgOp().

663 {
664  Assert(builder->state == SNAPBUILD_CONSISTENT);
665 
666  /* only build a new snapshot if we don't have a prebuilt one */
667  if (builder->snapshot == NULL)
668  {
669  builder->snapshot = SnapBuildBuildSnapshot(builder);
670  /* increase refcount for the snapshot builder */
672  }
673 
674  return builder->snapshot;
675 }
Snapshot snapshot
Definition: snapbuild.c:190
SnapBuildState state
Definition: snapbuild.c:150
static Snapshot SnapBuildBuildSnapshot(SnapBuild *builder)
Definition: snapbuild.c:450
#define Assert(condition)
Definition: c.h:804
static void SnapBuildSnapIncRefcount(Snapshot snap)
Definition: snapbuild.c:406

◆ SnapBuildGetTwoPhaseAt()

XLogRecPtr SnapBuildGetTwoPhaseAt ( SnapBuild builder)

Definition at line 376 of file snapbuild.c.

References SnapBuild::two_phase_at.

Referenced by DecodeCommit().

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

◆ SnapBuildInitialSnapshot()

Snapshot SnapBuildInitialSnapshot ( SnapBuild builder)

Definition at line 530 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().

531 {
532  Snapshot snap;
533  TransactionId xid;
534  TransactionId *newxip;
535  int newxcnt = 0;
536 
539 
540  if (builder->state != SNAPBUILD_CONSISTENT)
541  elog(ERROR, "cannot build an initial slot snapshot before reaching a consistent state");
542 
543  if (!builder->committed.includes_all_transactions)
544  elog(ERROR, "cannot build an initial slot snapshot, not all transactions are monitored anymore");
545 
546  /* so we don't overwrite the existing value */
548  elog(ERROR, "cannot build an initial slot snapshot when MyProc->xmin already is valid");
549 
550  snap = SnapBuildBuildSnapshot(builder);
551 
552  /*
553  * We know that snap->xmin is alive, enforced by the logical xmin
554  * mechanism. Due to that we can do this without locks, we're only
555  * changing our own value.
556  */
557 #ifdef USE_ASSERT_CHECKING
558  {
559  TransactionId safeXid;
560 
561  LWLockAcquire(ProcArrayLock, LW_SHARED);
562  safeXid = GetOldestSafeDecodingTransactionId(false);
563  LWLockRelease(ProcArrayLock);
564 
565  Assert(TransactionIdPrecedesOrEquals(safeXid, snap->xmin));
566  }
567 #endif
568 
569  MyProc->xmin = snap->xmin;
570 
571  /* allocate in transaction context */
572  newxip = (TransactionId *)
574 
575  /*
576  * snapbuild.c builds transactions in an "inverted" manner, which means it
577  * stores committed transactions in ->xip, not ones in progress. Build a
578  * classical snapshot by marking all non-committed transactions as
579  * in-progress. This can be expensive.
580  */
581  for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);)
582  {
583  void *test;
584 
585  /*
586  * Check whether transaction committed using the decoding snapshot
587  * meaning of ->xip.
588  */
589  test = bsearch(&xid, snap->xip, snap->xcnt,
590  sizeof(TransactionId), xidComparator);
591 
592  if (test == NULL)
593  {
594  if (newxcnt >= GetMaxSnapshotXidCount())
595  ereport(ERROR,
596  (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
597  errmsg("initial slot snapshot too large")));
598 
599  newxip[newxcnt++] = xid;
600  }
601 
603  }
604 
605  /* adjust remaining snapshot fields as needed */
607  snap->xcnt = newxcnt;
608  snap->xip = newxip;
609 
610  return snap;
611 }
#define TransactionIdAdvance(dest)
Definition: transam.h:91
TransactionId GetOldestSafeDecodingTransactionId(bool catalogOnly)
Definition: procarray.c:2947
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:698
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1803
SnapBuildState state
Definition: snapbuild.c:150
bool TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2)
Definition: transam.c:319
#define ERROR
Definition: elog.h:46
bool FirstSnapshotSet
Definition: snapmgr.c:149
TransactionId xmin
Definition: proc.h:138
static Snapshot SnapBuildBuildSnapshot(SnapBuild *builder)
Definition: snapbuild.c:450
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:157
int GetMaxSnapshotXidCount(void)
Definition: procarray.c:2069
#define Assert(condition)
Definition: c.h:804
int XactIsoLevel
Definition: xact.c:75
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1199
#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:1062
int errmsg(const char *fmt,...)
Definition: elog.c:909
#define elog(elevel,...)
Definition: elog.h:232
#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 706 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().

707 {
708  /*
709  * We can't handle data in transactions if we haven't built a snapshot
710  * yet, so don't store them.
711  */
712  if (builder->state < SNAPBUILD_FULL_SNAPSHOT)
713  return false;
714 
715  /*
716  * No point in keeping track of changes in transactions that we don't have
717  * enough information about to decode. This means that they started before
718  * we got into the SNAPBUILD_FULL_SNAPSHOT state.
719  */
720  if (builder->state < SNAPBUILD_CONSISTENT &&
721  TransactionIdPrecedes(xid, builder->next_phase_at))
722  return false;
723 
724  /*
725  * If the reorderbuffer doesn't yet have a snapshot, add one now, it will
726  * be needed to decode the change we're currently processing.
727  */
728  if (!ReorderBufferXidHasBaseSnapshot(builder->reorder, xid))
729  {
730  /* only build a new snapshot if we don't have a prebuilt one */
731  if (builder->snapshot == NULL)
732  {
733  builder->snapshot = SnapBuildBuildSnapshot(builder);
734  /* increase refcount for the snapshot builder */
736  }
737 
738  /*
739  * Increase refcount for the transaction we're handing the snapshot
740  * out to.
741  */
743  ReorderBufferSetBaseSnapshot(builder->reorder, xid, lsn,
744  builder->snapshot);
745  }
746 
747  return true;
748 }
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:450
bool TransactionIdPrecedes(TransactionId id1, TransactionId id2)
Definition: transam.c:300
static void SnapBuildSnapIncRefcount(Snapshot snap)
Definition: snapbuild.c:406

◆ SnapBuildProcessNewCid()

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

Definition at line 756 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().

758 {
759  CommandId cid;
760 
761  /*
762  * we only log new_cid's if a catalog tuple was modified, so mark the
763  * transaction as containing catalog modifications
764  */
765  ReorderBufferXidSetCatalogChanges(builder->reorder, xid, lsn);
766 
767  ReorderBufferAddNewTupleCids(builder->reorder, xlrec->top_xid, lsn,
768  xlrec->target_node, xlrec->target_tid,
769  xlrec->cmin, xlrec->cmax,
770  xlrec->combocid);
771 
772  /* figure out new command id */
773  if (xlrec->cmin != InvalidCommandId &&
774  xlrec->cmax != InvalidCommandId)
775  cid = Max(xlrec->cmin, xlrec->cmax);
776  else if (xlrec->cmax != InvalidCommandId)
777  cid = xlrec->cmax;
778  else if (xlrec->cmin != InvalidCommandId)
779  cid = xlrec->cmin;
780  else
781  {
782  cid = InvalidCommandId; /* silence compiler */
783  elog(ERROR, "xl_heap_new_cid record without a valid CommandId");
784  }
785 
786  ReorderBufferAddNewCommandId(builder->reorder, xid, lsn, cid + 1);
787 }
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:46
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:232
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 1088 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().

1089 {
1090  ReorderBufferTXN *txn;
1091  TransactionId xmin;
1092 
1093  /*
1094  * If we're not consistent yet, inspect the record to see whether it
1095  * allows to get closer to being consistent. If we are consistent, dump
1096  * our snapshot so others or we, after a restart, can use it.
1097  */
1098  if (builder->state < SNAPBUILD_CONSISTENT)
1099  {
1100  /* returns false if there's no point in performing cleanup just yet */
1101  if (!SnapBuildFindSnapshot(builder, lsn, running))
1102  return;
1103  }
1104  else
1105  SnapBuildSerialize(builder, lsn);
1106 
1107  /*
1108  * Update range of interesting xids based on the running xacts
1109  * information. We don't increase ->xmax using it, because once we are in
1110  * a consistent state we can do that ourselves and much more efficiently
1111  * so, because we only need to do it for catalog transactions since we
1112  * only ever look at those.
1113  *
1114  * NB: We only increase xmax when a catalog modifying transaction commits
1115  * (see SnapBuildCommitTxn). Because of this, xmax can be lower than
1116  * xmin, which looks odd but is correct and actually more efficient, since
1117  * we hit fast paths in heapam_visibility.c.
1118  */
1119  builder->xmin = running->oldestRunningXid;
1120 
1121  /* Remove transactions we don't need to keep track off anymore */
1122  SnapBuildPurgeCommittedTxn(builder);
1123 
1124  /*
1125  * Advance the xmin limit for the current replication slot, to allow
1126  * vacuum to clean up the tuples this slot has been protecting.
1127  *
1128  * The reorderbuffer might have an xmin among the currently running
1129  * snapshots; use it if so. If not, we need only consider the snapshots
1130  * we'll produce later, which can't be less than the oldest running xid in
1131  * the record we're reading now.
1132  */
1133  xmin = ReorderBufferGetOldestXmin(builder->reorder);
1134  if (xmin == InvalidTransactionId)
1135  xmin = running->oldestRunningXid;
1136  elog(DEBUG3, "xmin: %u, xmax: %u, oldest running: %u, oldest xmin: %u",
1137  builder->xmin, builder->xmax, running->oldestRunningXid, xmin);
1138  LogicalIncreaseXminForSlot(lsn, xmin);
1139 
1140  /*
1141  * Also tell the slot where we can restart decoding from. We don't want to
1142  * do that after every commit because changing that implies an fsync of
1143  * the logical slot's state file, so we only do it every time we see a
1144  * running xacts record.
1145  *
1146  * Do so by looking for the oldest in progress transaction (determined by
1147  * the first LSN of any of its relevant records). Every transaction
1148  * remembers the last location we stored the snapshot to disk before its
1149  * beginning. That point is where we can restart from.
1150  */
1151 
1152  /*
1153  * Can't know about a serialized snapshot's location if we're not
1154  * consistent.
1155  */
1156  if (builder->state < SNAPBUILD_CONSISTENT)
1157  return;
1158 
1159  txn = ReorderBufferGetOldestTXN(builder->reorder);
1160 
1161  /*
1162  * oldest ongoing txn might have started when we didn't yet serialize
1163  * anything because we hadn't reached a consistent state yet.
1164  */
1165  if (txn != NULL && txn->restart_decoding_lsn != InvalidXLogRecPtr)
1167 
1168  /*
1169  * No in-progress transaction, can reuse the last serialized snapshot if
1170  * we have one.
1171  */
1172  else if (txn == NULL &&
1176  builder->last_serialized_snapshot);
1177 }
#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:1632
XLogRecPtr current_restart_decoding_lsn
static bool SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *running)
Definition: snapbuild.c:1190
SnapBuildState state
Definition: snapbuild.c:150
static void SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
Definition: snapbuild.c:1478
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:1564
TransactionId xmin
Definition: snapbuild.c:156
#define elog(elevel,...)
Definition: elog.h:232
XLogRecPtr restart_decoding_lsn
TransactionId oldestRunningXid
Definition: standbydefs.h:53
static void SnapBuildPurgeCommittedTxn(SnapBuild *builder)
Definition: snapbuild.c:880

◆ SnapBuildSerializationPoint()

void SnapBuildSerializationPoint ( SnapBuild builder,
XLogRecPtr  lsn 
)

Definition at line 1465 of file snapbuild.c.

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

Referenced by DecodeXLogOp().

1466 {
1467  if (builder->state < SNAPBUILD_CONSISTENT)
1468  SnapBuildRestore(builder, lsn);
1469  else
1470  SnapBuildSerialize(builder, lsn);
1471 }
static bool SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
Definition: snapbuild.c:1690
SnapBuildState state
Definition: snapbuild.c:150
static void SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
Definition: snapbuild.c:1478

◆ SnapBuildSetTwoPhaseAt()

void SnapBuildSetTwoPhaseAt ( SnapBuild builder,
XLogRecPtr  ptr 
)

Definition at line 385 of file snapbuild.c.

References SnapBuild::two_phase_at.

Referenced by CreateDecodingContext().

386 {
387  builder->two_phase_at = ptr;
388 }
XLogRecPtr two_phase_at
Definition: snapbuild.c:176

◆ SnapBuildSnapDecRefcount()

void SnapBuildSnapDecRefcount ( Snapshot  snap)

Definition at line 418 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().

419 {
420  /* make sure we don't get passed an external snapshot */
422 
423  /* make sure nobody modified our snapshot */
424  Assert(snap->curcid == FirstCommandId);
425  Assert(!snap->suboverflowed);
426  Assert(!snap->takenDuringRecovery);
427 
428  Assert(snap->regd_count == 0);
429 
430  Assert(snap->active_count > 0);
431 
432  /* slightly more likely, so it's checked even without casserts */
433  if (snap->copied)
434  elog(ERROR, "cannot free a copied snapshot");
435 
436  snap->active_count--;
437  if (snap->active_count == 0)
438  SnapBuildFreeSnapshot(snap);
439 }
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:46
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:232
uint32 active_count
Definition: snapshot.h:204

◆ SnapBuildXactNeedsSkip()

bool SnapBuildXactNeedsSkip ( SnapBuild snapstate,
XLogRecPtr  ptr 
)

Definition at line 394 of file snapbuild.c.

References SnapBuild::start_decoding_at.

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

395 {
396  return ptr < builder->start_decoding_at;
397 }