PostgreSQL Source Code  git master
clog.h File Reference
#include "access/xlogreader.h"
#include "storage/sync.h"
#include "lib/stringinfo.h"
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Data Structures

struct  xl_clog_truncate
 

Macros

#define TRANSACTION_STATUS_IN_PROGRESS   0x00
 
#define TRANSACTION_STATUS_COMMITTED   0x01
 
#define TRANSACTION_STATUS_ABORTED   0x02
 
#define TRANSACTION_STATUS_SUB_COMMITTED   0x03
 
#define CLOG_ZEROPAGE   0x00
 
#define CLOG_TRUNCATE   0x10
 

Typedefs

typedef int XidStatus
 
typedef struct xl_clog_truncate xl_clog_truncate
 

Functions

void TransactionIdSetTreeStatus (TransactionId xid, int nsubxids, TransactionId *subxids, XidStatus status, XLogRecPtr lsn)
 
XidStatus TransactionIdGetStatus (TransactionId xid, XLogRecPtr *lsn)
 
Size CLOGShmemBuffers (void)
 
Size CLOGShmemSize (void)
 
void CLOGShmemInit (void)
 
void BootStrapCLOG (void)
 
void StartupCLOG (void)
 
void TrimCLOG (void)
 
void ShutdownCLOG (void)
 
void CheckPointCLOG (void)
 
void ExtendCLOG (TransactionId newestXact)
 
void TruncateCLOG (TransactionId oldestXact, Oid oldestxid_datoid)
 
int clogsyncfiletag (const FileTag *ftag, char *path)
 
void clog_redo (XLogReaderState *record)
 
void clog_desc (StringInfo buf, XLogReaderState *record)
 
const char * clog_identify (uint8 info)
 

Macro Definition Documentation

◆ CLOG_TRUNCATE

#define CLOG_TRUNCATE   0x10

Definition at line 58 of file clog.h.

Referenced by clog_desc(), clog_identify(), clog_redo(), and WriteTruncateXlogRec().

◆ CLOG_ZEROPAGE

#define CLOG_ZEROPAGE   0x00

Definition at line 57 of file clog.h.

Referenced by clog_desc(), clog_identify(), clog_redo(), and WriteZeroPageXlogRec().

◆ TRANSACTION_STATUS_ABORTED

#define TRANSACTION_STATUS_ABORTED   0x02

◆ TRANSACTION_STATUS_COMMITTED

◆ TRANSACTION_STATUS_IN_PROGRESS

#define TRANSACTION_STATUS_IN_PROGRESS   0x00

Definition at line 27 of file clog.h.

Referenced by InitProcess(), TransactionIdSetStatusBit(), and TransactionLogFetch().

◆ TRANSACTION_STATUS_SUB_COMMITTED

#define TRANSACTION_STATUS_SUB_COMMITTED   0x03

Typedef Documentation

◆ XidStatus

typedef int XidStatus

Definition at line 25 of file clog.h.

◆ xl_clog_truncate

Function Documentation

◆ BootStrapCLOG()

void BootStrapCLOG ( void  )

Definition at line 706 of file clog.c.

References Assert, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), SimpleLruWritePage(), XactCtl, and ZeroCLOGPage().

Referenced by BootStrapXLOG().

707 {
708  int slotno;
709 
710  LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);
711 
712  /* Create and zero the first page of the commit log */
713  slotno = ZeroCLOGPage(0, false);
714 
715  /* Make sure it's written out */
716  SimpleLruWritePage(XactCtl, slotno);
717  Assert(!XactCtl->shared->page_dirty[slotno]);
718 
719  LWLockRelease(XactSLRULock);
720 }
#define XactCtl
Definition: clog.c:89
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1812
void SimpleLruWritePage(SlruCtl ctl, int slotno)
Definition: slru.c:613
#define Assert(condition)
Definition: c.h:746
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1208
static int ZeroCLOGPage(int pageno, bool writeXlog)
Definition: clog.c:732

◆ CheckPointCLOG()

void CheckPointCLOG ( void  )

Definition at line 817 of file clog.c.

References SimpleLruWriteAll(), and XactCtl.

Referenced by CheckPointGuts().

818 {
819  /*
820  * Write dirty CLOG pages to disk. This may result in sync requests
821  * queued for later handling by ProcessSyncRequests(), as part of the
822  * checkpoint.
823  */
824  TRACE_POSTGRESQL_CLOG_CHECKPOINT_START(true);
825  SimpleLruWriteAll(XactCtl, true);
826  TRACE_POSTGRESQL_CLOG_CHECKPOINT_DONE(true);
827 }
#define XactCtl
Definition: clog.c:89
void SimpleLruWriteAll(SlruCtl ctl, bool allow_redirtied)
Definition: slru.c:1155

◆ clog_desc()

void clog_desc ( StringInfo  buf,
XLogReaderState record 
)

Definition at line 21 of file clogdesc.c.

References appendStringInfo(), CLOG_TRUNCATE, CLOG_ZEROPAGE, xl_clog_truncate::oldestXact, xl_clog_truncate::pageno, XLogRecGetData, XLogRecGetInfo, and XLR_INFO_MASK.

22 {
23  char *rec = XLogRecGetData(record);
24  uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
25 
26  if (info == CLOG_ZEROPAGE)
27  {
28  int pageno;
29 
30  memcpy(&pageno, rec, sizeof(int));
31  appendStringInfo(buf, "page %d", pageno);
32  }
33  else if (info == CLOG_TRUNCATE)
34  {
35  xl_clog_truncate xlrec;
36 
37  memcpy(&xlrec, rec, sizeof(xl_clog_truncate));
38  appendStringInfo(buf, "page %d; oldestXact %u",
39  xlrec.pageno, xlrec.oldestXact);
40  }
41 }
unsigned char uint8
Definition: c.h:373
#define CLOG_ZEROPAGE
Definition: clog.h:57
#define XLogRecGetData(decoder)
Definition: xlogreader.h:310
void appendStringInfo(StringInfo str, const char *fmt,...)
Definition: stringinfo.c:91
int pageno
Definition: clog.h:34
#define CLOG_TRUNCATE
Definition: clog.h:58
#define XLogRecGetInfo(decoder)
Definition: xlogreader.h:305
TransactionId oldestXact
Definition: clog.h:35
#define XLR_INFO_MASK
Definition: xlogrecord.h:62

◆ clog_identify()

const char* clog_identify ( uint8  info)

Definition at line 44 of file clogdesc.c.

References CLOG_TRUNCATE, CLOG_ZEROPAGE, and XLR_INFO_MASK.

45 {
46  const char *id = NULL;
47 
48  switch (info & ~XLR_INFO_MASK)
49  {
50  case CLOG_ZEROPAGE:
51  id = "ZEROPAGE";
52  break;
53  case CLOG_TRUNCATE:
54  id = "TRUNCATE";
55  break;
56  }
57 
58  return id;
59 }
#define CLOG_ZEROPAGE
Definition: clog.h:57
#define CLOG_TRUNCATE
Definition: clog.h:58
#define XLR_INFO_MASK
Definition: xlogrecord.h:62

◆ clog_redo()

void clog_redo ( XLogReaderState record)

Definition at line 975 of file clog.c.

References AdvanceOldestClogXid(), Assert, CLOG_TRUNCATE, CLOG_ZEROPAGE, elog, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), xl_clog_truncate::oldestXact, xl_clog_truncate::pageno, PANIC, SimpleLruTruncate(), SimpleLruWritePage(), XactCtl, XLogRecGetData, XLogRecGetInfo, XLogRecHasAnyBlockRefs, XLR_INFO_MASK, and ZeroCLOGPage().

976 {
977  uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
978 
979  /* Backup blocks are not used in clog records */
980  Assert(!XLogRecHasAnyBlockRefs(record));
981 
982  if (info == CLOG_ZEROPAGE)
983  {
984  int pageno;
985  int slotno;
986 
987  memcpy(&pageno, XLogRecGetData(record), sizeof(int));
988 
989  LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);
990 
991  slotno = ZeroCLOGPage(pageno, false);
992  SimpleLruWritePage(XactCtl, slotno);
993  Assert(!XactCtl->shared->page_dirty[slotno]);
994 
995  LWLockRelease(XactSLRULock);
996  }
997  else if (info == CLOG_TRUNCATE)
998  {
999  xl_clog_truncate xlrec;
1000 
1001  memcpy(&xlrec, XLogRecGetData(record), sizeof(xl_clog_truncate));
1002 
1003  /*
1004  * During XLOG replay, latest_page_number isn't set up yet; insert a
1005  * suitable value to bypass the sanity test in SimpleLruTruncate.
1006  */
1007  XactCtl->shared->latest_page_number = xlrec.pageno;
1008 
1010 
1012  }
1013  else
1014  elog(PANIC, "clog_redo: unknown op code %u", info);
1015 }
void SimpleLruTruncate(SlruCtl ctl, int cutoffPage)
Definition: slru.c:1225
#define XactCtl
Definition: clog.c:89
unsigned char uint8
Definition: c.h:373
#define PANIC
Definition: elog.h:53
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1812
#define CLOG_ZEROPAGE
Definition: clog.h:57
void AdvanceOldestClogXid(TransactionId oldest_datfrozenxid)
Definition: varsup.c:328
#define XLogRecGetData(decoder)
Definition: xlogreader.h:310
void SimpleLruWritePage(SlruCtl ctl, int slotno)
Definition: slru.c:613
int pageno
Definition: clog.h:34
#define CLOG_TRUNCATE
Definition: clog.h:58
#define XLogRecGetInfo(decoder)
Definition: xlogreader.h:305
TransactionId oldestXact
Definition: clog.h:35
#define Assert(condition)
Definition: c.h:746
#define XLR_INFO_MASK
Definition: xlogrecord.h:62
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1208
static int ZeroCLOGPage(int pageno, bool writeXlog)
Definition: clog.c:732
#define elog(elevel,...)
Definition: elog.h:214
#define XLogRecHasAnyBlockRefs(decoder)
Definition: xlogreader.h:312

◆ CLOGShmemBuffers()

Size CLOGShmemBuffers ( void  )

Definition at line 676 of file clog.c.

References Max, Min, and NBuffers.

Referenced by CLOGShmemInit(), and CLOGShmemSize().

677 {
678  return Min(128, Max(4, NBuffers / 512));
679 }
#define Min(x, y)
Definition: c.h:928
#define Max(x, y)
Definition: c.h:922
int NBuffers
Definition: globals.c:132

◆ CLOGShmemInit()

void CLOGShmemInit ( void  )

Definition at line 691 of file clog.c.

References CLOG_LSNS_PER_PAGE, CLOGPagePrecedes(), CLOGShmemBuffers(), LWTRANCHE_XACT_BUFFER, SimpleLruInit(), SYNC_HANDLER_CLOG, and XactCtl.

Referenced by CreateSharedMemoryAndSemaphores().

692 {
693  XactCtl->PagePrecedes = CLOGPagePrecedes;
695  XactSLRULock, "pg_xact", LWTRANCHE_XACT_BUFFER,
697 }
#define XactCtl
Definition: clog.c:89
void SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns, LWLock *ctllock, const char *subdir, int tranche_id, SyncRequestHandler sync_handler)
Definition: slru.c:186
#define CLOG_LSNS_PER_PAGE
Definition: clog.c:72
static bool CLOGPagePrecedes(int page1, int page2)
Definition: clog.c:924
Size CLOGShmemBuffers(void)
Definition: clog.c:676

◆ CLOGShmemSize()

Size CLOGShmemSize ( void  )

Definition at line 685 of file clog.c.

References CLOG_LSNS_PER_PAGE, CLOGShmemBuffers(), and SimpleLruShmemSize().

Referenced by CreateSharedMemoryAndSemaphores().

686 {
688 }
Size SimpleLruShmemSize(int nslots, int nlsns)
Definition: slru.c:155
#define CLOG_LSNS_PER_PAGE
Definition: clog.c:72
Size CLOGShmemBuffers(void)
Definition: clog.c:676

◆ clogsyncfiletag()

int clogsyncfiletag ( const FileTag ftag,
char *  path 
)

Definition at line 1021 of file clog.c.

References SlruSyncFileTag(), and XactCtl.

1022 {
1023  return SlruSyncFileTag(XactCtl, ftag, path);
1024 }
int SlruSyncFileTag(SlruCtl ctl, const FileTag *ftag, char *path)
Definition: slru.c:1489
#define XactCtl
Definition: clog.c:89

◆ ExtendCLOG()

void ExtendCLOG ( TransactionId  newestXact)

Definition at line 839 of file clog.c.

References FirstNormalTransactionId, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), TransactionIdEquals, TransactionIdToPage, TransactionIdToPgIndex, and ZeroCLOGPage().

Referenced by GetNewTransactionId().

840 {
841  int pageno;
842 
843  /*
844  * No work except at first XID of a page. But beware: just after
845  * wraparound, the first XID of page zero is FirstNormalTransactionId.
846  */
847  if (TransactionIdToPgIndex(newestXact) != 0 &&
849  return;
850 
851  pageno = TransactionIdToPage(newestXact);
852 
853  LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);
854 
855  /* Zero the page and make an XLOG entry about it */
856  ZeroCLOGPage(pageno, true);
857 
858  LWLockRelease(XactSLRULock);
859 }
#define TransactionIdToPage(xid)
Definition: clog.c:65
#define TransactionIdEquals(id1, id2)
Definition: transam.h:43
#define TransactionIdToPgIndex(xid)
Definition: clog.c:66
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1812
#define FirstNormalTransactionId
Definition: transam.h:34
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1208
static int ZeroCLOGPage(int pageno, bool writeXlog)
Definition: clog.c:732

◆ ShutdownCLOG()

void ShutdownCLOG ( void  )

◆ StartupCLOG()

void StartupCLOG ( void  )

Definition at line 749 of file clog.c.

References LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), VariableCacheData::nextXid, ShmemVariableCache, TransactionIdToPage, XactCtl, and XidFromFullTransactionId.

Referenced by StartupXLOG().

750 {
752  int pageno = TransactionIdToPage(xid);
753 
754  LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);
755 
756  /*
757  * Initialize our idea of the latest page number.
758  */
759  XactCtl->shared->latest_page_number = pageno;
760 
761  LWLockRelease(XactSLRULock);
762 }
#define TransactionIdToPage(xid)
Definition: clog.c:65
uint32 TransactionId
Definition: c.h:521
#define XactCtl
Definition: clog.c:89
FullTransactionId nextXid
Definition: transam.h:213
#define XidFromFullTransactionId(x)
Definition: transam.h:48
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1812
VariableCache ShmemVariableCache
Definition: varsup.c:34
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1208

◆ TransactionIdGetStatus()

XidStatus TransactionIdGetStatus ( TransactionId  xid,
XLogRecPtr lsn 
)

Definition at line 634 of file clog.c.

References CLOG_BITS_PER_XACT, CLOG_XACT_BITMASK, GetLSNIndex, LWLockRelease(), SimpleLruReadPage_ReadOnly(), status(), TransactionIdToBIndex, TransactionIdToByte, TransactionIdToPage, and XactCtl.

Referenced by TransactionIdGetCommitLSN(), and TransactionLogFetch().

635 {
636  int pageno = TransactionIdToPage(xid);
637  int byteno = TransactionIdToByte(xid);
638  int bshift = TransactionIdToBIndex(xid) * CLOG_BITS_PER_XACT;
639  int slotno;
640  int lsnindex;
641  char *byteptr;
643 
644  /* lock is acquired by SimpleLruReadPage_ReadOnly */
645 
646  slotno = SimpleLruReadPage_ReadOnly(XactCtl, pageno, xid);
647  byteptr = XactCtl->shared->page_buffer[slotno] + byteno;
648 
649  status = (*byteptr >> bshift) & CLOG_XACT_BITMASK;
650 
651  lsnindex = GetLSNIndex(slotno, xid);
652  *lsn = XactCtl->shared->group_lsn[lsnindex];
653 
654  LWLockRelease(XactSLRULock);
655 
656  return status;
657 }
#define TransactionIdToBIndex(xid)
Definition: clog.c:68
#define CLOG_XACT_BITMASK
Definition: clog.c:63
#define TransactionIdToPage(xid)
Definition: clog.c:65
#define GetLSNIndex(slotno, xid)
Definition: clog.c:74
#define XactCtl
Definition: clog.c:89
int XidStatus
Definition: clog.h:25
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1812
#define CLOG_BITS_PER_XACT
Definition: clog.c:60
int SimpleLruReadPage_ReadOnly(SlruCtl ctl, int pageno, TransactionId xid)
Definition: slru.c:494
#define TransactionIdToByte(xid)
Definition: clog.c:67
static void static void status(const char *fmt,...) pg_attribute_printf(1
Definition: pg_regress.c:227

◆ TransactionIdSetTreeStatus()

void TransactionIdSetTreeStatus ( TransactionId  xid,
int  nsubxids,
TransactionId subxids,
XidStatus  status,
XLogRecPtr  lsn 
)

Definition at line 164 of file clog.c.

References Assert, i, set_status_by_pages(), TRANSACTION_STATUS_ABORTED, TRANSACTION_STATUS_COMMITTED, TRANSACTION_STATUS_SUB_COMMITTED, TransactionIdSetPageStatus(), and TransactionIdToPage.

Referenced by TransactionIdAbortTree(), TransactionIdAsyncCommitTree(), and TransactionIdCommitTree().

166 {
167  int pageno = TransactionIdToPage(xid); /* get page of parent */
168  int i;
169 
172 
173  /*
174  * See how many subxids, if any, are on the same page as the parent, if
175  * any.
176  */
177  for (i = 0; i < nsubxids; i++)
178  {
179  if (TransactionIdToPage(subxids[i]) != pageno)
180  break;
181  }
182 
183  /*
184  * Do all items fit on a single page?
185  */
186  if (i == nsubxids)
187  {
188  /*
189  * Set the parent and all subtransactions in a single call
190  */
191  TransactionIdSetPageStatus(xid, nsubxids, subxids, status, lsn,
192  pageno, true);
193  }
194  else
195  {
196  int nsubxids_on_first_page = i;
197 
198  /*
199  * If this is a commit then we care about doing this correctly (i.e.
200  * using the subcommitted intermediate status). By here, we know
201  * we're updating more than one page of clog, so we must mark entries
202  * that are *not* on the first page so that they show as subcommitted
203  * before we then return to update the status to fully committed.
204  *
205  * To avoid touching the first page twice, skip marking subcommitted
206  * for the subxids on that first page.
207  */
209  set_status_by_pages(nsubxids - nsubxids_on_first_page,
210  subxids + nsubxids_on_first_page,
212 
213  /*
214  * Now set the parent and subtransactions on same page as the parent,
215  * if any
216  */
217  pageno = TransactionIdToPage(xid);
218  TransactionIdSetPageStatus(xid, nsubxids_on_first_page, subxids, status,
219  lsn, pageno, false);
220 
221  /*
222  * Now work through the rest of the subxids one clog page at a time,
223  * starting from the second page onwards, like we did above.
224  */
225  set_status_by_pages(nsubxids - nsubxids_on_first_page,
226  subxids + nsubxids_on_first_page,
227  status, lsn);
228  }
229 }
#define TransactionIdToPage(xid)
Definition: clog.c:65
#define TRANSACTION_STATUS_COMMITTED
Definition: clog.h:28
#define TRANSACTION_STATUS_ABORTED
Definition: clog.h:29
#define TRANSACTION_STATUS_SUB_COMMITTED
Definition: clog.h:30
static void set_status_by_pages(int nsubxids, TransactionId *subxids, XidStatus status, XLogRecPtr lsn)
Definition: clog.c:238
#define Assert(condition)
Definition: c.h:746
static void TransactionIdSetPageStatus(TransactionId xid, int nsubxids, TransactionId *subxids, XidStatus status, XLogRecPtr lsn, int pageno, bool all_xact_same_page)
Definition: clog.c:274
int i
static void static void status(const char *fmt,...) pg_attribute_printf(1
Definition: pg_regress.c:227

◆ TrimCLOG()

void TrimCLOG ( void  )

Definition at line 768 of file clog.c.

References CLOG_BITS_PER_XACT, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MemSet, VariableCacheData::nextXid, ShmemVariableCache, SimpleLruReadPage(), TransactionIdToBIndex, TransactionIdToByte, TransactionIdToPage, TransactionIdToPgIndex, XactCtl, and XidFromFullTransactionId.

Referenced by StartupXLOG().

769 {
771  int pageno = TransactionIdToPage(xid);
772 
773  LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);
774 
775  /*
776  * Re-Initialize our idea of the latest page number.
777  */
778  XactCtl->shared->latest_page_number = pageno;
779 
780  /*
781  * Zero out the remainder of the current clog page. Under normal
782  * circumstances it should be zeroes already, but it seems at least
783  * theoretically possible that XLOG replay will have settled on a nextXID
784  * value that is less than the last XID actually used and marked by the
785  * previous database lifecycle (since subtransaction commit writes clog
786  * but makes no WAL entry). Let's just be safe. (We need not worry about
787  * pages beyond the current one, since those will be zeroed when first
788  * used. For the same reason, there is no need to do anything when
789  * nextXid is exactly at a page boundary; and it's likely that the
790  * "current" page doesn't exist yet in that case.)
791  */
792  if (TransactionIdToPgIndex(xid) != 0)
793  {
794  int byteno = TransactionIdToByte(xid);
795  int bshift = TransactionIdToBIndex(xid) * CLOG_BITS_PER_XACT;
796  int slotno;
797  char *byteptr;
798 
799  slotno = SimpleLruReadPage(XactCtl, pageno, false, xid);
800  byteptr = XactCtl->shared->page_buffer[slotno] + byteno;
801 
802  /* Zero so-far-unused positions in the current byte */
803  *byteptr &= (1 << bshift) - 1;
804  /* Zero the rest of the page */
805  MemSet(byteptr + 1, 0, BLCKSZ - byteno - 1);
806 
807  XactCtl->shared->page_dirty[slotno] = true;
808  }
809 
810  LWLockRelease(XactSLRULock);
811 }
#define TransactionIdToBIndex(xid)
Definition: clog.c:68
#define TransactionIdToPage(xid)
Definition: clog.c:65
uint32 TransactionId
Definition: c.h:521
#define TransactionIdToPgIndex(xid)
Definition: clog.c:66
#define XactCtl
Definition: clog.c:89
#define MemSet(start, val, len)
Definition: c.h:950
FullTransactionId nextXid
Definition: transam.h:213
#define XidFromFullTransactionId(x)
Definition: transam.h:48
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1812
int SimpleLruReadPage(SlruCtl ctl, int pageno, bool write_ok, TransactionId xid)
Definition: slru.c:394
VariableCache ShmemVariableCache
Definition: varsup.c:34
#define CLOG_BITS_PER_XACT
Definition: clog.c:60
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1208
#define TransactionIdToByte(xid)
Definition: clog.c:67

◆ TruncateCLOG()

void TruncateCLOG ( TransactionId  oldestXact,
Oid  oldestxid_datoid 
)

Definition at line 878 of file clog.c.

References AdvanceOldestClogXid(), SimpleLruTruncate(), SlruScanDirCbReportPresence(), SlruScanDirectory(), TransactionIdToPage, WriteTruncateXlogRec(), and XactCtl.

Referenced by vac_truncate_clog().

879 {
880  int cutoffPage;
881 
882  /*
883  * The cutoff point is the start of the segment containing oldestXact. We
884  * pass the *page* containing oldestXact to SimpleLruTruncate.
885  */
886  cutoffPage = TransactionIdToPage(oldestXact);
887 
888  /* Check to see if there's any files that could be removed */
890  return; /* nothing to remove */
891 
892  /*
893  * Advance oldestClogXid before truncating clog, so concurrent xact status
894  * lookups can ensure they don't attempt to access truncated-away clog.
895  *
896  * It's only necessary to do this if we will actually truncate away clog
897  * pages.
898  */
899  AdvanceOldestClogXid(oldestXact);
900 
901  /*
902  * Write XLOG record and flush XLOG to disk. We record the oldest xid
903  * we're keeping information about here so we can ensure that it's always
904  * ahead of clog truncation in case we crash, and so a standby finds out
905  * the new valid xid before the next checkpoint.
906  */
907  WriteTruncateXlogRec(cutoffPage, oldestXact, oldestxid_datoid);
908 
909  /* Now we can remove the old CLOG segment(s) */
910  SimpleLruTruncate(XactCtl, cutoffPage);
911 }
#define TransactionIdToPage(xid)
Definition: clog.c:65
void SimpleLruTruncate(SlruCtl ctl, int cutoffPage)
Definition: slru.c:1225
#define XactCtl
Definition: clog.c:89
void AdvanceOldestClogXid(TransactionId oldest_datfrozenxid)
Definition: varsup.c:328
static void WriteTruncateXlogRec(int pageno, TransactionId oldestXact, Oid oldestXactDb)
Definition: clog.c:956
bool SlruScanDirCbReportPresence(SlruCtl ctl, char *filename, int segpage, void *data)
Definition: slru.c:1394
bool SlruScanDirectory(SlruCtl ctl, SlruScanCallback callback, void *data)
Definition: slru.c:1449