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 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 57 of file clog.h.

◆ CLOG_ZEROPAGE

#define CLOG_ZEROPAGE   0x00

Definition at line 56 of file clog.h.

◆ TRANSACTION_STATUS_ABORTED

#define TRANSACTION_STATUS_ABORTED   0x02

Definition at line 29 of file clog.h.

◆ TRANSACTION_STATUS_COMMITTED

#define TRANSACTION_STATUS_COMMITTED   0x01

Definition at line 28 of file clog.h.

◆ TRANSACTION_STATUS_IN_PROGRESS

#define TRANSACTION_STATUS_IN_PROGRESS   0x00

Definition at line 27 of file clog.h.

◆ TRANSACTION_STATUS_SUB_COMMITTED

#define TRANSACTION_STATUS_SUB_COMMITTED   0x03

Definition at line 30 of file clog.h.

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 711 of file clog.c.

712 {
713  int slotno;
714 
715  LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);
716 
717  /* Create and zero the first page of the commit log */
718  slotno = ZeroCLOGPage(0, false);
719 
720  /* Make sure it's written out */
721  SimpleLruWritePage(XactCtl, slotno);
722  Assert(!XactCtl->shared->page_dirty[slotno]);
723 
724  LWLockRelease(XactSLRULock);
725 }
#define XactCtl
Definition: clog.c:89
static int ZeroCLOGPage(int pageno, bool writeXlog)
Definition: clog.c:737
Assert(fmt[strlen(fmt) - 1] !='\n')
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1194
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1802
@ LW_EXCLUSIVE
Definition: lwlock.h:112
void SimpleLruWritePage(SlruCtl ctl, int slotno)
Definition: slru.c:615

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

Referenced by BootStrapXLOG().

◆ CheckPointCLOG()

void CheckPointCLOG ( void  )

Definition at line 817 of file clog.c.

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 }
void SimpleLruWriteAll(SlruCtl ctl, bool allow_redirtied)
Definition: slru.c:1157

References SimpleLruWriteAll(), and XactCtl.

Referenced by CheckPointGuts().

◆ clog_desc()

void clog_desc ( StringInfo  buf,
XLogReaderState record 
)

Definition at line 21 of file clogdesc.c.

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:440
#define CLOG_ZEROPAGE
Definition: clog.h:56
#define CLOG_TRUNCATE
Definition: clog.h:57
static char * buf
Definition: pg_test_fsync.c:67
void appendStringInfo(StringInfo str, const char *fmt,...)
Definition: stringinfo.c:91
int pageno
Definition: clog.h:34
TransactionId oldestXact
Definition: clog.h:35
#define XLogRecGetInfo(decoder)
Definition: xlogreader.h:411
#define XLogRecGetData(decoder)
Definition: xlogreader.h:416
#define XLR_INFO_MASK
Definition: xlogrecord.h:62

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

◆ clog_identify()

const char* clog_identify ( uint8  info)

Definition at line 44 of file clogdesc.c.

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 }

References CLOG_TRUNCATE, CLOG_ZEROPAGE, and XLR_INFO_MASK.

◆ clog_redo()

void clog_redo ( XLogReaderState record)

Definition at line 985 of file clog.c.

986 {
987  uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
988 
989  /* Backup blocks are not used in clog records */
990  Assert(!XLogRecHasAnyBlockRefs(record));
991 
992  if (info == CLOG_ZEROPAGE)
993  {
994  int pageno;
995  int slotno;
996 
997  memcpy(&pageno, XLogRecGetData(record), sizeof(int));
998 
999  LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);
1000 
1001  slotno = ZeroCLOGPage(pageno, false);
1002  SimpleLruWritePage(XactCtl, slotno);
1003  Assert(!XactCtl->shared->page_dirty[slotno]);
1004 
1005  LWLockRelease(XactSLRULock);
1006  }
1007  else if (info == CLOG_TRUNCATE)
1008  {
1009  xl_clog_truncate xlrec;
1010 
1011  memcpy(&xlrec, XLogRecGetData(record), sizeof(xl_clog_truncate));
1012 
1014 
1016  }
1017  else
1018  elog(PANIC, "clog_redo: unknown op code %u", info);
1019 }
#define PANIC
Definition: elog.h:38
void SimpleLruTruncate(SlruCtl ctl, int cutoffPage)
Definition: slru.c:1227
void AdvanceOldestClogXid(TransactionId oldest_datfrozenxid)
Definition: varsup.c:328
#define XLogRecHasAnyBlockRefs(decoder)
Definition: xlogreader.h:418

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().

◆ CLOGShmemBuffers()

Size CLOGShmemBuffers ( void  )

Definition at line 680 of file clog.c.

681 {
682  return Min(128, Max(4, NBuffers / 512));
683 }
#define Min(x, y)
Definition: c.h:937
#define Max(x, y)
Definition: c.h:931
int NBuffers
Definition: globals.c:136

References Max, Min, and NBuffers.

Referenced by CLOGShmemInit(), and CLOGShmemSize().

◆ CLOGShmemInit()

void CLOGShmemInit ( void  )

Definition at line 695 of file clog.c.

696 {
697  XactCtl->PagePrecedes = CLOGPagePrecedes;
699  XactSLRULock, "pg_xact", LWTRANCHE_XACT_BUFFER,
702 }
#define CLOG_XACTS_PER_PAGE
Definition: clog.c:62
static bool CLOGPagePrecedes(int page1, int page2)
Definition: clog.c:933
Size CLOGShmemBuffers(void)
Definition: clog.c:680
#define CLOG_LSNS_PER_PAGE
Definition: clog.c:72
@ LWTRANCHE_XACT_BUFFER
Definition: lwlock.h:177
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:188
#define SlruPagePrecedesUnitTests(ctl, per_page)
Definition: slru.h:156
@ SYNC_HANDLER_CLOG
Definition: sync.h:38

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

Referenced by CreateSharedMemoryAndSemaphores().

◆ CLOGShmemSize()

Size CLOGShmemSize ( void  )

Definition at line 689 of file clog.c.

690 {
692 }
Size SimpleLruShmemSize(int nslots, int nlsns)
Definition: slru.c:156

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

Referenced by CalculateShmemSize().

◆ clogsyncfiletag()

int clogsyncfiletag ( const FileTag ftag,
char *  path 
)

Definition at line 1025 of file clog.c.

1026 {
1027  return SlruSyncFileTag(XactCtl, ftag, path);
1028 }
int SlruSyncFileTag(SlruCtl ctl, const FileTag *ftag, char *path)
Definition: slru.c:1594

References SlruSyncFileTag(), and XactCtl.

◆ ExtendCLOG()

void ExtendCLOG ( TransactionId  newestXact)

Definition at line 839 of file clog.c.

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 TransactionIdToPgIndex(xid)
Definition: clog.c:66
#define TransactionIdToPage(xid)
Definition: clog.c:65
#define TransactionIdEquals(id1, id2)
Definition: transam.h:43
#define FirstNormalTransactionId
Definition: transam.h:34

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

Referenced by GetNewTransactionId().

◆ StartupCLOG()

void StartupCLOG ( void  )

Definition at line 754 of file clog.c.

755 {
757  int pageno = TransactionIdToPage(xid);
758 
759  LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);
760 
761  /*
762  * Initialize our idea of the latest page number.
763  */
764  XactCtl->shared->latest_page_number = pageno;
765 
766  LWLockRelease(XactSLRULock);
767 }
uint32 TransactionId
Definition: c.h:588
FullTransactionId nextXid
Definition: transam.h:220
#define XidFromFullTransactionId(x)
Definition: transam.h:48
VariableCache ShmemVariableCache
Definition: varsup.c:34

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

Referenced by StartupXLOG().

◆ TransactionIdGetStatus()

XidStatus TransactionIdGetStatus ( TransactionId  xid,
XLogRecPtr lsn 
)

Definition at line 638 of file clog.c.

639 {
640  int pageno = TransactionIdToPage(xid);
641  int byteno = TransactionIdToByte(xid);
642  int bshift = TransactionIdToBIndex(xid) * CLOG_BITS_PER_XACT;
643  int slotno;
644  int lsnindex;
645  char *byteptr;
647 
648  /* lock is acquired by SimpleLruReadPage_ReadOnly */
649 
650  slotno = SimpleLruReadPage_ReadOnly(XactCtl, pageno, xid);
651  byteptr = XactCtl->shared->page_buffer[slotno] + byteno;
652 
653  status = (*byteptr >> bshift) & CLOG_XACT_BITMASK;
654 
655  lsnindex = GetLSNIndex(slotno, xid);
656  *lsn = XactCtl->shared->group_lsn[lsnindex];
657 
658  LWLockRelease(XactSLRULock);
659 
660  return status;
661 }
#define CLOG_XACT_BITMASK
Definition: clog.c:63
#define TransactionIdToBIndex(xid)
Definition: clog.c:68
#define CLOG_BITS_PER_XACT
Definition: clog.c:60
#define TransactionIdToByte(xid)
Definition: clog.c:67
#define GetLSNIndex(slotno, xid)
Definition: clog.c:74
int XidStatus
Definition: clog.h:25
static void static void status(const char *fmt,...) pg_attribute_printf(1
Definition: pg_regress.c:225
int SimpleLruReadPage_ReadOnly(SlruCtl ctl, int pageno, TransactionId xid)
Definition: slru.c:496

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

Referenced by TransactionIdGetCommitLSN(), and TransactionLogFetch().

◆ TransactionIdSetTreeStatus()

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

Definition at line 162 of file clog.c.

164 {
165  int pageno = TransactionIdToPage(xid); /* get page of parent */
166  int i;
167 
170 
171  /*
172  * See how many subxids, if any, are on the same page as the parent, if
173  * any.
174  */
175  for (i = 0; i < nsubxids; i++)
176  {
177  if (TransactionIdToPage(subxids[i]) != pageno)
178  break;
179  }
180 
181  /*
182  * Do all items fit on a single page?
183  */
184  if (i == nsubxids)
185  {
186  /*
187  * Set the parent and all subtransactions in a single call
188  */
189  TransactionIdSetPageStatus(xid, nsubxids, subxids, status, lsn,
190  pageno, true);
191  }
192  else
193  {
194  int nsubxids_on_first_page = i;
195 
196  /*
197  * If this is a commit then we care about doing this correctly (i.e.
198  * using the subcommitted intermediate status). By here, we know
199  * we're updating more than one page of clog, so we must mark entries
200  * that are *not* on the first page so that they show as subcommitted
201  * before we then return to update the status to fully committed.
202  *
203  * To avoid touching the first page twice, skip marking subcommitted
204  * for the subxids on that first page.
205  */
207  set_status_by_pages(nsubxids - nsubxids_on_first_page,
208  subxids + nsubxids_on_first_page,
210 
211  /*
212  * Now set the parent and subtransactions on same page as the parent,
213  * if any
214  */
215  pageno = TransactionIdToPage(xid);
216  TransactionIdSetPageStatus(xid, nsubxids_on_first_page, subxids, status,
217  lsn, pageno, false);
218 
219  /*
220  * Now work through the rest of the subxids one clog page at a time,
221  * starting from the second page onwards, like we did above.
222  */
223  set_status_by_pages(nsubxids - nsubxids_on_first_page,
224  subxids + nsubxids_on_first_page,
225  status, lsn);
226  }
227 }
static void TransactionIdSetPageStatus(TransactionId xid, int nsubxids, TransactionId *subxids, XidStatus status, XLogRecPtr lsn, int pageno, bool all_xact_same_page)
Definition: clog.c:272
static void set_status_by_pages(int nsubxids, TransactionId *subxids, XidStatus status, XLogRecPtr lsn)
Definition: clog.c:236
#define TRANSACTION_STATUS_ABORTED
Definition: clog.h:29
#define TRANSACTION_STATUS_SUB_COMMITTED
Definition: clog.h:30
#define TRANSACTION_STATUS_COMMITTED
Definition: clog.h:28
int i
Definition: isn.c:73

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

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

◆ TrimCLOG()

void TrimCLOG ( void  )

Definition at line 773 of file clog.c.

774 {
776  int pageno = TransactionIdToPage(xid);
777 
778  LWLockAcquire(XactSLRULock, LW_EXCLUSIVE);
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 MemSet(start, val, len)
Definition: c.h:953
int SimpleLruReadPage(SlruCtl ctl, int pageno, bool write_ok, TransactionId xid)
Definition: slru.c:396

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

Referenced by StartupXLOG().

◆ TruncateCLOG()

void TruncateCLOG ( TransactionId  oldestXact,
Oid  oldestxid_datoid 
)

Definition at line 878 of file clog.c.

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 }
static void WriteTruncateXlogRec(int pageno, TransactionId oldestXact, Oid oldestXactDb)
Definition: clog.c:966
bool SlruScanDirCbReportPresence(SlruCtl ctl, char *filename, int segpage, void *data)
Definition: slru.c:1501
bool SlruScanDirectory(SlruCtl ctl, SlruScanCallback callback, void *data)
Definition: slru.c:1554

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

Referenced by vac_truncate_clog().