PostgreSQL Source Code git master
xlogreader.c File Reference
#include "postgres.h"
#include <unistd.h>
#include "access/transam.h"
#include "access/xlog_internal.h"
#include "access/xlogreader.h"
#include "access/xlogrecord.h"
#include "catalog/pg_control.h"
#include "common/pg_lzcompress.h"
#include "replication/origin.h"
#include "pgstat.h"
#include "storage/bufmgr.h"
Include dependency graph for xlogreader.c:

Go to the source code of this file.

Macros

#define MAX_ERRORMSG_LEN   1000
 
#define DEFAULT_DECODE_BUFFER_SIZE   (64 * 1024)
 
#define COPY_HEADER_FIELD(_dst, _size)
 

Functions

static void report_invalid_record (XLogReaderState *state, const char *fmt,...) pg_attribute_printf(2
 
static void static void allocate_recordbuf (XLogReaderState *state, uint32 reclength)
 
static int ReadPageInternal (XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
 
static void XLogReaderInvalReadState (XLogReaderState *state)
 
static XLogPageReadResult XLogDecodeNextRecord (XLogReaderState *state, bool nonblocking)
 
static bool ValidXLogRecordHeader (XLogReaderState *state, XLogRecPtr RecPtr, XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess)
 
static bool ValidXLogRecord (XLogReaderState *state, XLogRecord *record, XLogRecPtr recptr)
 
static void ResetDecoder (XLogReaderState *state)
 
static void WALOpenSegmentInit (WALOpenSegment *seg, WALSegmentContext *segcxt, int segsize, const char *waldir)
 
void XLogReaderSetDecodeBuffer (XLogReaderState *state, void *buffer, size_t size)
 
XLogReaderStateXLogReaderAllocate (int wal_segment_size, const char *waldir, XLogReaderRoutine *routine, void *private_data)
 
void XLogReaderFree (XLogReaderState *state)
 
void XLogBeginRead (XLogReaderState *state, XLogRecPtr RecPtr)
 
XLogRecPtr XLogReleasePreviousRecord (XLogReaderState *state)
 
DecodedXLogRecordXLogNextRecord (XLogReaderState *state, char **errormsg)
 
XLogRecordXLogReadRecord (XLogReaderState *state, char **errormsg)
 
static DecodedXLogRecordXLogReadRecordAlloc (XLogReaderState *state, size_t xl_tot_len, bool allow_oversized)
 
DecodedXLogRecordXLogReadAhead (XLogReaderState *state, bool nonblocking)
 
bool XLogReaderValidatePageHeader (XLogReaderState *state, XLogRecPtr recptr, char *phdr)
 
void XLogReaderResetError (XLogReaderState *state)
 
XLogRecPtr XLogFindNextRecord (XLogReaderState *state, XLogRecPtr RecPtr)
 
bool WALRead (XLogReaderState *state, char *buf, XLogRecPtr startptr, Size count, TimeLineID tli, WALReadError *errinfo)
 
size_t DecodeXLogRecordRequiredSpace (size_t xl_tot_len)
 
bool DecodeXLogRecord (XLogReaderState *state, DecodedXLogRecord *decoded, XLogRecord *record, XLogRecPtr lsn, char **errormsg)
 
void XLogRecGetBlockTag (XLogReaderState *record, uint8 block_id, RelFileLocator *rlocator, ForkNumber *forknum, BlockNumber *blknum)
 
bool XLogRecGetBlockTagExtended (XLogReaderState *record, uint8 block_id, RelFileLocator *rlocator, ForkNumber *forknum, BlockNumber *blknum, Buffer *prefetch_buffer)
 
char * XLogRecGetBlockData (XLogReaderState *record, uint8 block_id, Size *len)
 
bool RestoreBlockImage (XLogReaderState *record, uint8 block_id, char *page)
 
FullTransactionId XLogRecGetFullXid (XLogReaderState *record)
 

Macro Definition Documentation

◆ COPY_HEADER_FIELD

#define COPY_HEADER_FIELD (   _dst,
  _size 
)
Value:
do { \
if (remaining < _size) \
goto shortdata_err; \
memcpy(_dst, ptr, _size); \
ptr += _size; \
remaining -= _size; \
} while(0)
int remaining
Definition: informix.c:692

◆ DEFAULT_DECODE_BUFFER_SIZE

#define DEFAULT_DECODE_BUFFER_SIZE   (64 * 1024)

Definition at line 65 of file xlogreader.c.

◆ MAX_ERRORMSG_LEN

#define MAX_ERRORMSG_LEN   1000

Definition at line 59 of file xlogreader.c.

Function Documentation

◆ allocate_recordbuf()

static void allocate_recordbuf ( XLogReaderState state,
uint32  reclength 
)
static

Definition at line 191 of file xlogreader.c.

192{
193 uint32 newSize = reclength;
194
195 newSize += XLOG_BLCKSZ - (newSize % XLOG_BLCKSZ);
196 newSize = Max(newSize, 5 * Max(BLCKSZ, XLOG_BLCKSZ));
197
198 if (state->readRecordBuf)
199 pfree(state->readRecordBuf);
200 state->readRecordBuf = (char *) palloc(newSize);
201 state->readRecordBufSize = newSize;
202}
#define Max(x, y)
Definition: c.h:969
uint32_t uint32
Definition: c.h:502
void pfree(void *pointer)
Definition: mcxt.c:1524
void * palloc(Size size)
Definition: mcxt.c:1317
Definition: regguts.h:323

References Max, palloc(), and pfree().

Referenced by XLogDecodeNextRecord(), and XLogReaderAllocate().

◆ DecodeXLogRecord()

bool DecodeXLogRecord ( XLogReaderState state,
DecodedXLogRecord decoded,
XLogRecord record,
XLogRecPtr  lsn,
char **  errormsg 
)

Definition at line 1672 of file xlogreader.c.

1677{
1678 /*
1679 * read next _size bytes from record buffer, but check for overrun first.
1680 */
1681#define COPY_HEADER_FIELD(_dst, _size) \
1682 do { \
1683 if (remaining < _size) \
1684 goto shortdata_err; \
1685 memcpy(_dst, ptr, _size); \
1686 ptr += _size; \
1687 remaining -= _size; \
1688 } while(0)
1689
1690 char *ptr;
1691 char *out;
1693 uint32 datatotal;
1694 RelFileLocator *rlocator = NULL;
1695 uint8 block_id;
1696
1697 decoded->header = *record;
1698 decoded->lsn = lsn;
1699 decoded->next = NULL;
1702 decoded->main_data = NULL;
1703 decoded->main_data_len = 0;
1704 decoded->max_block_id = -1;
1705 ptr = (char *) record;
1706 ptr += SizeOfXLogRecord;
1708
1709 /* Decode the headers */
1710 datatotal = 0;
1711 while (remaining > datatotal)
1712 {
1713 COPY_HEADER_FIELD(&block_id, sizeof(uint8));
1714
1715 if (block_id == XLR_BLOCK_ID_DATA_SHORT)
1716 {
1717 /* XLogRecordDataHeaderShort */
1718 uint8 main_data_len;
1719
1720 COPY_HEADER_FIELD(&main_data_len, sizeof(uint8));
1721
1722 decoded->main_data_len = main_data_len;
1723 datatotal += main_data_len;
1724 break; /* by convention, the main data fragment is
1725 * always last */
1726 }
1727 else if (block_id == XLR_BLOCK_ID_DATA_LONG)
1728 {
1729 /* XLogRecordDataHeaderLong */
1730 uint32 main_data_len;
1731
1732 COPY_HEADER_FIELD(&main_data_len, sizeof(uint32));
1733 decoded->main_data_len = main_data_len;
1734 datatotal += main_data_len;
1735 break; /* by convention, the main data fragment is
1736 * always last */
1737 }
1738 else if (block_id == XLR_BLOCK_ID_ORIGIN)
1739 {
1740 COPY_HEADER_FIELD(&decoded->record_origin, sizeof(RepOriginId));
1741 }
1742 else if (block_id == XLR_BLOCK_ID_TOPLEVEL_XID)
1743 {
1744 COPY_HEADER_FIELD(&decoded->toplevel_xid, sizeof(TransactionId));
1745 }
1746 else if (block_id <= XLR_MAX_BLOCK_ID)
1747 {
1748 /* XLogRecordBlockHeader */
1749 DecodedBkpBlock *blk;
1750 uint8 fork_flags;
1751
1752 /* mark any intervening block IDs as not in use */
1753 for (int i = decoded->max_block_id + 1; i < block_id; ++i)
1754 decoded->blocks[i].in_use = false;
1755
1756 if (block_id <= decoded->max_block_id)
1757 {
1759 "out-of-order block_id %u at %X/%X",
1760 block_id,
1761 LSN_FORMAT_ARGS(state->ReadRecPtr));
1762 goto err;
1763 }
1764 decoded->max_block_id = block_id;
1765
1766 blk = &decoded->blocks[block_id];
1767 blk->in_use = true;
1768 blk->apply_image = false;
1769
1770 COPY_HEADER_FIELD(&fork_flags, sizeof(uint8));
1771 blk->forknum = fork_flags & BKPBLOCK_FORK_MASK;
1772 blk->flags = fork_flags;
1773 blk->has_image = ((fork_flags & BKPBLOCK_HAS_IMAGE) != 0);
1774 blk->has_data = ((fork_flags & BKPBLOCK_HAS_DATA) != 0);
1775
1777
1778 COPY_HEADER_FIELD(&blk->data_len, sizeof(uint16));
1779 /* cross-check that the HAS_DATA flag is set iff data_length > 0 */
1780 if (blk->has_data && blk->data_len == 0)
1781 {
1783 "BKPBLOCK_HAS_DATA set, but no data included at %X/%X",
1784 LSN_FORMAT_ARGS(state->ReadRecPtr));
1785 goto err;
1786 }
1787 if (!blk->has_data && blk->data_len != 0)
1788 {
1790 "BKPBLOCK_HAS_DATA not set, but data length is %u at %X/%X",
1791 (unsigned int) blk->data_len,
1792 LSN_FORMAT_ARGS(state->ReadRecPtr));
1793 goto err;
1794 }
1795 datatotal += blk->data_len;
1796
1797 if (blk->has_image)
1798 {
1799 COPY_HEADER_FIELD(&blk->bimg_len, sizeof(uint16));
1800 COPY_HEADER_FIELD(&blk->hole_offset, sizeof(uint16));
1801 COPY_HEADER_FIELD(&blk->bimg_info, sizeof(uint8));
1802
1803 blk->apply_image = ((blk->bimg_info & BKPIMAGE_APPLY) != 0);
1804
1806 {
1807 if (blk->bimg_info & BKPIMAGE_HAS_HOLE)
1808 COPY_HEADER_FIELD(&blk->hole_length, sizeof(uint16));
1809 else
1810 blk->hole_length = 0;
1811 }
1812 else
1813 blk->hole_length = BLCKSZ - blk->bimg_len;
1814 datatotal += blk->bimg_len;
1815
1816 /*
1817 * cross-check that hole_offset > 0, hole_length > 0 and
1818 * bimg_len < BLCKSZ if the HAS_HOLE flag is set.
1819 */
1820 if ((blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1821 (blk->hole_offset == 0 ||
1822 blk->hole_length == 0 ||
1823 blk->bimg_len == BLCKSZ))
1824 {
1826 "BKPIMAGE_HAS_HOLE set, but hole offset %u length %u block image length %u at %X/%X",
1827 (unsigned int) blk->hole_offset,
1828 (unsigned int) blk->hole_length,
1829 (unsigned int) blk->bimg_len,
1830 LSN_FORMAT_ARGS(state->ReadRecPtr));
1831 goto err;
1832 }
1833
1834 /*
1835 * cross-check that hole_offset == 0 and hole_length == 0 if
1836 * the HAS_HOLE flag is not set.
1837 */
1838 if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1839 (blk->hole_offset != 0 || blk->hole_length != 0))
1840 {
1842 "BKPIMAGE_HAS_HOLE not set, but hole offset %u length %u at %X/%X",
1843 (unsigned int) blk->hole_offset,
1844 (unsigned int) blk->hole_length,
1845 LSN_FORMAT_ARGS(state->ReadRecPtr));
1846 goto err;
1847 }
1848
1849 /*
1850 * Cross-check that bimg_len < BLCKSZ if it is compressed.
1851 */
1852 if (BKPIMAGE_COMPRESSED(blk->bimg_info) &&
1853 blk->bimg_len == BLCKSZ)
1854 {
1856 "BKPIMAGE_COMPRESSED set, but block image length %u at %X/%X",
1857 (unsigned int) blk->bimg_len,
1858 LSN_FORMAT_ARGS(state->ReadRecPtr));
1859 goto err;
1860 }
1861
1862 /*
1863 * cross-check that bimg_len = BLCKSZ if neither HAS_HOLE is
1864 * set nor COMPRESSED().
1865 */
1866 if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1868 blk->bimg_len != BLCKSZ)
1869 {
1871 "neither BKPIMAGE_HAS_HOLE nor BKPIMAGE_COMPRESSED set, but block image length is %u at %X/%X",
1872 (unsigned int) blk->data_len,
1873 LSN_FORMAT_ARGS(state->ReadRecPtr));
1874 goto err;
1875 }
1876 }
1877 if (!(fork_flags & BKPBLOCK_SAME_REL))
1878 {
1880 rlocator = &blk->rlocator;
1881 }
1882 else
1883 {
1884 if (rlocator == NULL)
1885 {
1887 "BKPBLOCK_SAME_REL set but no previous rel at %X/%X",
1888 LSN_FORMAT_ARGS(state->ReadRecPtr));
1889 goto err;
1890 }
1891
1892 blk->rlocator = *rlocator;
1893 }
1894 COPY_HEADER_FIELD(&blk->blkno, sizeof(BlockNumber));
1895 }
1896 else
1897 {
1899 "invalid block_id %u at %X/%X",
1900 block_id, LSN_FORMAT_ARGS(state->ReadRecPtr));
1901 goto err;
1902 }
1903 }
1904
1905 if (remaining != datatotal)
1906 goto shortdata_err;
1907
1908 /*
1909 * Ok, we've parsed the fragment headers, and verified that the total
1910 * length of the payload in the fragments is equal to the amount of data
1911 * left. Copy the data of each fragment to contiguous space after the
1912 * blocks array, inserting alignment padding before the data fragments so
1913 * they can be cast to struct pointers by REDO routines.
1914 */
1915 out = ((char *) decoded) +
1916 offsetof(DecodedXLogRecord, blocks) +
1917 sizeof(decoded->blocks[0]) * (decoded->max_block_id + 1);
1918
1919 /* block data first */
1920 for (block_id = 0; block_id <= decoded->max_block_id; block_id++)
1921 {
1922 DecodedBkpBlock *blk = &decoded->blocks[block_id];
1923
1924 if (!blk->in_use)
1925 continue;
1926
1927 Assert(blk->has_image || !blk->apply_image);
1928
1929 if (blk->has_image)
1930 {
1931 /* no need to align image */
1932 blk->bkp_image = out;
1933 memcpy(out, ptr, blk->bimg_len);
1934 ptr += blk->bimg_len;
1935 out += blk->bimg_len;
1936 }
1937 if (blk->has_data)
1938 {
1939 out = (char *) MAXALIGN(out);
1940 blk->data = out;
1941 memcpy(blk->data, ptr, blk->data_len);
1942 ptr += blk->data_len;
1943 out += blk->data_len;
1944 }
1945 }
1946
1947 /* and finally, the main data */
1948 if (decoded->main_data_len > 0)
1949 {
1950 out = (char *) MAXALIGN(out);
1951 decoded->main_data = out;
1952 memcpy(decoded->main_data, ptr, decoded->main_data_len);
1953 ptr += decoded->main_data_len;
1954 out += decoded->main_data_len;
1955 }
1956
1957 /* Report the actual size we used. */
1958 decoded->size = MAXALIGN(out - (char *) decoded);
1960 decoded->size);
1961
1962 return true;
1963
1964shortdata_err:
1966 "record with invalid length at %X/%X",
1967 LSN_FORMAT_ARGS(state->ReadRecPtr));
1968err:
1969 *errormsg = state->errormsg_buf;
1970
1971 return false;
1972}
uint32 BlockNumber
Definition: block.h:31
#define InvalidBuffer
Definition: buf.h:25
#define MAXALIGN(LEN)
Definition: c.h:782
uint8_t uint8
Definition: c.h:500
uint16_t uint16
Definition: c.h:501
uint32 TransactionId
Definition: c.h:623
void err(int eval, const char *fmt,...)
Definition: err.c:43
Assert(PointerIsAligned(start, uint64))
int i
Definition: isn.c:74
#define InvalidRepOriginId
Definition: origin.h:33
uint16 hole_length
Definition: xlogreader.h:140
char * bkp_image
Definition: xlogreader.h:138
Buffer prefetch_buffer
Definition: xlogreader.h:130
RelFileLocator rlocator
Definition: xlogreader.h:125
BlockNumber blkno
Definition: xlogreader.h:127
ForkNumber forknum
Definition: xlogreader.h:126
uint16 hole_offset
Definition: xlogreader.h:139
XLogRecord header
Definition: xlogreader.h:166
struct DecodedXLogRecord * next
Definition: xlogreader.h:161
TransactionId toplevel_xid
Definition: xlogreader.h:168
uint32 main_data_len
Definition: xlogreader.h:170
RepOriginId record_origin
Definition: xlogreader.h:167
DecodedBkpBlock blocks[FLEXIBLE_ARRAY_MEMBER]
Definition: xlogreader.h:172
XLogRecPtr lsn
Definition: xlogreader.h:164
uint32 xl_tot_len
Definition: xlogrecord.h:43
#define InvalidTransactionId
Definition: transam.h:31
#define LSN_FORMAT_ARGS(lsn)
Definition: xlogdefs.h:43
uint16 RepOriginId
Definition: xlogdefs.h:65
static void report_invalid_record(XLogReaderState *state, const char *fmt,...) pg_attribute_printf(2
Definition: xlogreader.c:72
#define COPY_HEADER_FIELD(_dst, _size)
size_t DecodeXLogRecordRequiredSpace(size_t xl_tot_len)
Definition: xlogreader.c:1639
#define BKPBLOCK_FORK_MASK
Definition: xlogrecord.h:195
#define BKPBLOCK_HAS_DATA
Definition: xlogrecord.h:198
#define BKPIMAGE_APPLY
Definition: xlogrecord.h:158
#define BKPIMAGE_HAS_HOLE
Definition: xlogrecord.h:157
#define XLR_BLOCK_ID_DATA_LONG
Definition: xlogrecord.h:242
#define BKPIMAGE_COMPRESSED(info)
Definition: xlogrecord.h:164
#define XLR_BLOCK_ID_TOPLEVEL_XID
Definition: xlogrecord.h:244
#define XLR_BLOCK_ID_DATA_SHORT
Definition: xlogrecord.h:241
#define XLR_MAX_BLOCK_ID
Definition: xlogrecord.h:239
#define BKPBLOCK_SAME_REL
Definition: xlogrecord.h:200
#define XLR_BLOCK_ID_ORIGIN
Definition: xlogrecord.h:243
#define SizeOfXLogRecord
Definition: xlogrecord.h:55
#define BKPBLOCK_HAS_IMAGE
Definition: xlogrecord.h:197

References DecodedBkpBlock::apply_image, Assert(), DecodedBkpBlock::bimg_info, DecodedBkpBlock::bimg_len, DecodedBkpBlock::bkp_image, BKPBLOCK_FORK_MASK, BKPBLOCK_HAS_DATA, BKPBLOCK_HAS_IMAGE, BKPBLOCK_SAME_REL, BKPIMAGE_APPLY, BKPIMAGE_COMPRESSED, BKPIMAGE_HAS_HOLE, DecodedBkpBlock::blkno, DecodedXLogRecord::blocks, COPY_HEADER_FIELD, DecodedBkpBlock::data, DecodedBkpBlock::data_len, DecodeXLogRecordRequiredSpace(), err(), DecodedBkpBlock::flags, DecodedBkpBlock::forknum, DecodedBkpBlock::has_data, DecodedBkpBlock::has_image, DecodedXLogRecord::header, DecodedBkpBlock::hole_length, DecodedBkpBlock::hole_offset, i, DecodedBkpBlock::in_use, InvalidBuffer, InvalidRepOriginId, InvalidTransactionId, DecodedXLogRecord::lsn, LSN_FORMAT_ARGS, DecodedXLogRecord::main_data, DecodedXLogRecord::main_data_len, DecodedXLogRecord::max_block_id, MAXALIGN, DecodedXLogRecord::next, DecodedBkpBlock::prefetch_buffer, DecodedXLogRecord::record_origin, remaining, report_invalid_record(), DecodedBkpBlock::rlocator, DecodedXLogRecord::size, SizeOfXLogRecord, DecodedXLogRecord::toplevel_xid, XLogRecord::xl_tot_len, XLR_BLOCK_ID_DATA_LONG, XLR_BLOCK_ID_DATA_SHORT, XLR_BLOCK_ID_ORIGIN, XLR_BLOCK_ID_TOPLEVEL_XID, and XLR_MAX_BLOCK_ID.

Referenced by XLogDecodeNextRecord(), and XLogInsertRecord().

◆ DecodeXLogRecordRequiredSpace()

size_t DecodeXLogRecordRequiredSpace ( size_t  xl_tot_len)

Definition at line 1639 of file xlogreader.c.

1640{
1641 size_t size = 0;
1642
1643 /* Account for the fixed size part of the decoded record struct. */
1644 size += offsetof(DecodedXLogRecord, blocks[0]);
1645 /* Account for the flexible blocks array of maximum possible size. */
1646 size += sizeof(DecodedBkpBlock) * (XLR_MAX_BLOCK_ID + 1);
1647 /* Account for all the raw main and block data. */
1648 size += xl_tot_len;
1649 /* We might insert padding before main_data. */
1650 size += (MAXIMUM_ALIGNOF - 1);
1651 /* We might insert padding before each block's data. */
1652 size += (MAXIMUM_ALIGNOF - 1) * (XLR_MAX_BLOCK_ID + 1);
1653 /* We might insert padding at the end. */
1654 size += (MAXIMUM_ALIGNOF - 1);
1655
1656 return size;
1657}

References XLR_MAX_BLOCK_ID.

Referenced by DecodeXLogRecord(), InitXLogInsert(), XLogInsertRecord(), and XLogReadRecordAlloc().

◆ ReadPageInternal()

static int ReadPageInternal ( XLogReaderState state,
XLogRecPtr  pageptr,
int  reqLen 
)
static

Definition at line 1001 of file xlogreader.c.

1002{
1003 int readLen;
1004 uint32 targetPageOff;
1005 XLogSegNo targetSegNo;
1006 XLogPageHeader hdr;
1007
1008 Assert((pageptr % XLOG_BLCKSZ) == 0);
1009
1010 XLByteToSeg(pageptr, targetSegNo, state->segcxt.ws_segsize);
1011 targetPageOff = XLogSegmentOffset(pageptr, state->segcxt.ws_segsize);
1012
1013 /* check whether we have all the requested data already */
1014 if (targetSegNo == state->seg.ws_segno &&
1015 targetPageOff == state->segoff && reqLen <= state->readLen)
1016 return state->readLen;
1017
1018 /*
1019 * Invalidate contents of internal buffer before read attempt. Just set
1020 * the length to 0, rather than a full XLogReaderInvalReadState(), so we
1021 * don't forget the segment we last successfully read.
1022 */
1023 state->readLen = 0;
1024
1025 /*
1026 * Data is not in our buffer.
1027 *
1028 * Every time we actually read the segment, even if we looked at parts of
1029 * it before, we need to do verification as the page_read callback might
1030 * now be rereading data from a different source.
1031 *
1032 * Whenever switching to a new WAL segment, we read the first page of the
1033 * file and validate its header, even if that's not where the target
1034 * record is. This is so that we can check the additional identification
1035 * info that is present in the first page's "long" header.
1036 */
1037 if (targetSegNo != state->seg.ws_segno && targetPageOff != 0)
1038 {
1039 XLogRecPtr targetSegmentPtr = pageptr - targetPageOff;
1040
1041 readLen = state->routine.page_read(state, targetSegmentPtr, XLOG_BLCKSZ,
1042 state->currRecPtr,
1043 state->readBuf);
1045 return XLREAD_WOULDBLOCK;
1046 else if (readLen < 0)
1047 goto err;
1048
1049 /* we can be sure to have enough WAL available, we scrolled back */
1050 Assert(readLen == XLOG_BLCKSZ);
1051
1052 if (!XLogReaderValidatePageHeader(state, targetSegmentPtr,
1053 state->readBuf))
1054 goto err;
1055 }
1056
1057 /*
1058 * First, read the requested data length, but at least a short page header
1059 * so that we can validate it.
1060 */
1061 readLen = state->routine.page_read(state, pageptr, Max(reqLen, SizeOfXLogShortPHD),
1062 state->currRecPtr,
1063 state->readBuf);
1065 return XLREAD_WOULDBLOCK;
1066 else if (readLen < 0)
1067 goto err;
1068
1069 Assert(readLen <= XLOG_BLCKSZ);
1070
1071 /* Do we have enough data to check the header length? */
1073 goto err;
1074
1075 Assert(readLen >= reqLen);
1076
1077 hdr = (XLogPageHeader) state->readBuf;
1078
1079 /* still not enough */
1081 {
1082 readLen = state->routine.page_read(state, pageptr, XLogPageHeaderSize(hdr),
1083 state->currRecPtr,
1084 state->readBuf);
1086 return XLREAD_WOULDBLOCK;
1087 else if (readLen < 0)
1088 goto err;
1089 }
1090
1091 /*
1092 * Now that we know we have the full header, validate it.
1093 */
1094 if (!XLogReaderValidatePageHeader(state, pageptr, (char *) hdr))
1095 goto err;
1096
1097 /* update read state information */
1098 state->seg.ws_segno = targetSegNo;
1099 state->segoff = targetPageOff;
1100 state->readLen = readLen;
1101
1102 return readLen;
1103
1104err:
1106
1107 return XLREAD_FAIL;
1108}
if(TABLE==NULL||TABLE_index==NULL)
Definition: isn.c:78
#define XLogSegmentOffset(xlogptr, wal_segsz_bytes)
XLogPageHeaderData * XLogPageHeader
Definition: xlog_internal.h:54
#define XLByteToSeg(xlrp, logSegNo, wal_segsz_bytes)
#define SizeOfXLogShortPHD
Definition: xlog_internal.h:52
#define XLogPageHeaderSize(hdr)
Definition: xlog_internal.h:84
uint64 XLogRecPtr
Definition: xlogdefs.h:21
uint64 XLogSegNo
Definition: xlogdefs.h:48
static void XLogReaderInvalReadState(XLogReaderState *state)
Definition: xlogreader.c:1114
bool XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr, char *phdr)
Definition: xlogreader.c:1225
@ XLREAD_WOULDBLOCK
Definition: xlogreader.h:353
@ XLREAD_FAIL
Definition: xlogreader.h:352
static uint32 readLen
Definition: xlogrecovery.c:234

References Assert(), err(), if(), Max, readLen, SizeOfXLogShortPHD, XLByteToSeg, XLogPageHeaderSize, XLogReaderInvalReadState(), XLogReaderValidatePageHeader(), XLogSegmentOffset, XLREAD_FAIL, and XLREAD_WOULDBLOCK.

Referenced by XLogDecodeNextRecord(), and XLogFindNextRecord().

◆ report_invalid_record()

static void report_invalid_record ( XLogReaderState state,
const char *  fmt,
  ... 
)
static

Definition at line 72 of file xlogreader.c.

73{
74 va_list args;
75
76 fmt = _(fmt);
77
78 va_start(args, fmt);
79 vsnprintf(state->errormsg_buf, MAX_ERRORMSG_LEN, fmt, args);
80 va_end(args);
81
82 state->errormsg_deferred = true;
83}
#define _(x)
Definition: elog.c:90
#define vsnprintf
Definition: port.h:238
#define MAX_ERRORMSG_LEN
Definition: xlogreader.c:59

References _, generate_unaccent_rules::args, MAX_ERRORMSG_LEN, and vsnprintf.

Referenced by DecodeXLogRecord(), RestoreBlockImage(), ValidXLogRecord(), ValidXLogRecordHeader(), XLogDecodeNextRecord(), and XLogReaderValidatePageHeader().

◆ ResetDecoder()

static void ResetDecoder ( XLogReaderState state)
static

Definition at line 1605 of file xlogreader.c.

1606{
1608
1609 /* Reset the decoded record queue, freeing any oversized records. */
1610 while ((r = state->decode_queue_head) != NULL)
1611 {
1612 state->decode_queue_head = r->next;
1613 if (r->oversized)
1614 pfree(r);
1615 }
1616 state->decode_queue_tail = NULL;
1617 state->decode_queue_head = NULL;
1618 state->record = NULL;
1619
1620 /* Reset the decode buffer to empty. */
1621 state->decode_buffer_tail = state->decode_buffer;
1622 state->decode_buffer_head = state->decode_buffer;
1623
1624 /* Clear error state. */
1625 state->errormsg_buf[0] = '\0';
1626 state->errormsg_deferred = false;
1627}

References DecodedXLogRecord::next, DecodedXLogRecord::oversized, and pfree().

Referenced by XLogBeginRead().

◆ RestoreBlockImage()

bool RestoreBlockImage ( XLogReaderState record,
uint8  block_id,
char *  page 
)

Definition at line 2066 of file xlogreader.c.

2067{
2068 DecodedBkpBlock *bkpb;
2069 char *ptr;
2070 PGAlignedBlock tmp;
2071
2072 if (block_id > record->record->max_block_id ||
2073 !record->record->blocks[block_id].in_use)
2074 {
2075 report_invalid_record(record,
2076 "could not restore image at %X/%X with invalid block %d specified",
2077 LSN_FORMAT_ARGS(record->ReadRecPtr),
2078 block_id);
2079 return false;
2080 }
2081 if (!record->record->blocks[block_id].has_image)
2082 {
2083 report_invalid_record(record, "could not restore image at %X/%X with invalid state, block %d",
2084 LSN_FORMAT_ARGS(record->ReadRecPtr),
2085 block_id);
2086 return false;
2087 }
2088
2089 bkpb = &record->record->blocks[block_id];
2090 ptr = bkpb->bkp_image;
2091
2092 if (BKPIMAGE_COMPRESSED(bkpb->bimg_info))
2093 {
2094 /* If a backup block image is compressed, decompress it */
2095 bool decomp_success = true;
2096
2097 if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_PGLZ) != 0)
2098 {
2099 if (pglz_decompress(ptr, bkpb->bimg_len, tmp.data,
2100 BLCKSZ - bkpb->hole_length, true) < 0)
2101 decomp_success = false;
2102 }
2103 else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_LZ4) != 0)
2104 {
2105#ifdef USE_LZ4
2106 if (LZ4_decompress_safe(ptr, tmp.data,
2107 bkpb->bimg_len, BLCKSZ - bkpb->hole_length) <= 0)
2108 decomp_success = false;
2109#else
2110 report_invalid_record(record, "could not restore image at %X/%X compressed with %s not supported by build, block %d",
2111 LSN_FORMAT_ARGS(record->ReadRecPtr),
2112 "LZ4",
2113 block_id);
2114 return false;
2115#endif
2116 }
2117 else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_ZSTD) != 0)
2118 {
2119#ifdef USE_ZSTD
2120 size_t decomp_result = ZSTD_decompress(tmp.data,
2121 BLCKSZ - bkpb->hole_length,
2122 ptr, bkpb->bimg_len);
2123
2124 if (ZSTD_isError(decomp_result))
2125 decomp_success = false;
2126#else
2127 report_invalid_record(record, "could not restore image at %X/%X compressed with %s not supported by build, block %d",
2128 LSN_FORMAT_ARGS(record->ReadRecPtr),
2129 "zstd",
2130 block_id);
2131 return false;
2132#endif
2133 }
2134 else
2135 {
2136 report_invalid_record(record, "could not restore image at %X/%X compressed with unknown method, block %d",
2137 LSN_FORMAT_ARGS(record->ReadRecPtr),
2138 block_id);
2139 return false;
2140 }
2141
2142 if (!decomp_success)
2143 {
2144 report_invalid_record(record, "could not decompress image at %X/%X, block %d",
2145 LSN_FORMAT_ARGS(record->ReadRecPtr),
2146 block_id);
2147 return false;
2148 }
2149
2150 ptr = tmp.data;
2151 }
2152
2153 /* generate page, taking into account hole if necessary */
2154 if (bkpb->hole_length == 0)
2155 {
2156 memcpy(page, ptr, BLCKSZ);
2157 }
2158 else
2159 {
2160 memcpy(page, ptr, bkpb->hole_offset);
2161 /* must zero-fill the hole */
2162 MemSet(page + bkpb->hole_offset, 0, bkpb->hole_length);
2163 memcpy(page + (bkpb->hole_offset + bkpb->hole_length),
2164 ptr + bkpb->hole_offset,
2165 BLCKSZ - (bkpb->hole_offset + bkpb->hole_length));
2166 }
2167
2168 return true;
2169}
#define MemSet(start, val, len)
Definition: c.h:991
int32 pglz_decompress(const char *source, int32 slen, char *dest, int32 rawsize, bool check_complete)
DecodedXLogRecord * record
Definition: xlogreader.h:236
XLogRecPtr ReadRecPtr
Definition: xlogreader.h:206
char data[BLCKSZ]
Definition: c.h:1090
#define BKPIMAGE_COMPRESS_ZSTD
Definition: xlogrecord.h:162
#define BKPIMAGE_COMPRESS_LZ4
Definition: xlogrecord.h:161
#define BKPIMAGE_COMPRESS_PGLZ
Definition: xlogrecord.h:160

References DecodedBkpBlock::bimg_info, DecodedBkpBlock::bimg_len, DecodedBkpBlock::bkp_image, BKPIMAGE_COMPRESS_LZ4, BKPIMAGE_COMPRESS_PGLZ, BKPIMAGE_COMPRESS_ZSTD, BKPIMAGE_COMPRESSED, DecodedXLogRecord::blocks, PGAlignedBlock::data, DecodedBkpBlock::has_image, DecodedBkpBlock::hole_length, DecodedBkpBlock::hole_offset, DecodedBkpBlock::in_use, LSN_FORMAT_ARGS, DecodedXLogRecord::max_block_id, MemSet, pglz_decompress(), XLogReaderState::ReadRecPtr, XLogReaderState::record, and report_invalid_record().

Referenced by GetWALBlockInfo(), verifyBackupPageConsistency(), XLogReadBufferForRedoExtended(), and XLogRecordSaveFPWs().

◆ ValidXLogRecord()

static bool ValidXLogRecord ( XLogReaderState state,
XLogRecord record,
XLogRecPtr  recptr 
)
static

Definition at line 1194 of file xlogreader.c.

1195{
1196 pg_crc32c crc;
1197
1199
1200 /* Calculate the CRC */
1202 COMP_CRC32C(crc, ((char *) record) + SizeOfXLogRecord, record->xl_tot_len - SizeOfXLogRecord);
1203 /* include the record header last */
1204 COMP_CRC32C(crc, (char *) record, offsetof(XLogRecord, xl_crc));
1205 FIN_CRC32C(crc);
1206
1207 if (!EQ_CRC32C(record->xl_crc, crc))
1208 {
1210 "incorrect resource manager data checksum in record at %X/%X",
1211 LSN_FORMAT_ARGS(recptr));
1212 return false;
1213 }
1214
1215 return true;
1216}
uint32 pg_crc32c
Definition: pg_crc32c.h:38
#define COMP_CRC32C(crc, data, len)
Definition: pg_crc32c.h:98
#define EQ_CRC32C(c1, c2)
Definition: pg_crc32c.h:42
#define INIT_CRC32C(crc)
Definition: pg_crc32c.h:41
#define FIN_CRC32C(crc)
Definition: pg_crc32c.h:103
return crc

References Assert(), COMP_CRC32C, crc, EQ_CRC32C, FIN_CRC32C, INIT_CRC32C, LSN_FORMAT_ARGS, report_invalid_record(), SizeOfXLogRecord, XLogRecord::xl_crc, and XLogRecord::xl_tot_len.

Referenced by XLogDecodeNextRecord().

◆ ValidXLogRecordHeader()

static bool ValidXLogRecordHeader ( XLogReaderState state,
XLogRecPtr  RecPtr,
XLogRecPtr  PrevRecPtr,
XLogRecord record,
bool  randAccess 
)
static

Definition at line 1128 of file xlogreader.c.

1131{
1132 if (record->xl_tot_len < SizeOfXLogRecord)
1133 {
1135 "invalid record length at %X/%X: expected at least %u, got %u",
1136 LSN_FORMAT_ARGS(RecPtr),
1138 return false;
1139 }
1140 if (!RmgrIdIsValid(record->xl_rmid))
1141 {
1143 "invalid resource manager ID %u at %X/%X",
1144 record->xl_rmid, LSN_FORMAT_ARGS(RecPtr));
1145 return false;
1146 }
1147 if (randAccess)
1148 {
1149 /*
1150 * We can't exactly verify the prev-link, but surely it should be less
1151 * than the record's own address.
1152 */
1153 if (!(record->xl_prev < RecPtr))
1154 {
1156 "record with incorrect prev-link %X/%X at %X/%X",
1157 LSN_FORMAT_ARGS(record->xl_prev),
1158 LSN_FORMAT_ARGS(RecPtr));
1159 return false;
1160 }
1161 }
1162 else
1163 {
1164 /*
1165 * Record's prev-link should exactly match our previous location. This
1166 * check guards against torn WAL pages where a stale but valid-looking
1167 * WAL record starts on a sector boundary.
1168 */
1169 if (record->xl_prev != PrevRecPtr)
1170 {
1172 "record with incorrect prev-link %X/%X at %X/%X",
1173 LSN_FORMAT_ARGS(record->xl_prev),
1174 LSN_FORMAT_ARGS(RecPtr));
1175 return false;
1176 }
1177 }
1178
1179 return true;
1180}
#define RmgrIdIsValid(rmid)
Definition: rmgr.h:53
XLogRecPtr xl_prev
Definition: xlogrecord.h:45
RmgrId xl_rmid
Definition: xlogrecord.h:47

References LSN_FORMAT_ARGS, report_invalid_record(), RmgrIdIsValid, SizeOfXLogRecord, XLogRecord::xl_prev, XLogRecord::xl_rmid, and XLogRecord::xl_tot_len.

Referenced by XLogDecodeNextRecord().

◆ WALOpenSegmentInit()

static void WALOpenSegmentInit ( WALOpenSegment seg,
WALSegmentContext segcxt,
int  segsize,
const char *  waldir 
)
static

Definition at line 208 of file xlogreader.c.

210{
211 seg->ws_file = -1;
212 seg->ws_segno = 0;
213 seg->ws_tli = 0;
214
215 segcxt->ws_segsize = segsize;
216 if (waldir)
217 snprintf(segcxt->ws_dir, MAXPGPATH, "%s", waldir);
218}
#define MAXPGPATH
#define snprintf
Definition: port.h:239
XLogSegNo ws_segno
Definition: xlogreader.h:48
TimeLineID ws_tli
Definition: xlogreader.h:49
char ws_dir[MAXPGPATH]
Definition: xlogreader.h:55

References MAXPGPATH, snprintf, WALSegmentContext::ws_dir, WALOpenSegment::ws_file, WALOpenSegment::ws_segno, WALSegmentContext::ws_segsize, and WALOpenSegment::ws_tli.

Referenced by XLogReaderAllocate().

◆ WALRead()

bool WALRead ( XLogReaderState state,
char *  buf,
XLogRecPtr  startptr,
Size  count,
TimeLineID  tli,
WALReadError errinfo 
)

Definition at line 1504 of file xlogreader.c.

1507{
1508 char *p;
1509 XLogRecPtr recptr;
1510 Size nbytes;
1511#ifndef FRONTEND
1512 instr_time io_start;
1513#endif
1514
1515 p = buf;
1516 recptr = startptr;
1517 nbytes = count;
1518
1519 while (nbytes > 0)
1520 {
1521 uint32 startoff;
1522 int segbytes;
1523 int readbytes;
1524
1525 startoff = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
1526
1527 /*
1528 * If the data we want is not in a segment we have open, close what we
1529 * have (if anything) and open the next one, using the caller's
1530 * provided segment_open callback.
1531 */
1532 if (state->seg.ws_file < 0 ||
1533 !XLByteInSeg(recptr, state->seg.ws_segno, state->segcxt.ws_segsize) ||
1534 tli != state->seg.ws_tli)
1535 {
1536 XLogSegNo nextSegNo;
1537
1538 if (state->seg.ws_file >= 0)
1539 state->routine.segment_close(state);
1540
1541 XLByteToSeg(recptr, nextSegNo, state->segcxt.ws_segsize);
1542 state->routine.segment_open(state, nextSegNo, &tli);
1543
1544 /* This shouldn't happen -- indicates a bug in segment_open */
1545 Assert(state->seg.ws_file >= 0);
1546
1547 /* Update the current segment info. */
1548 state->seg.ws_tli = tli;
1549 state->seg.ws_segno = nextSegNo;
1550 }
1551
1552 /* How many bytes are within this segment? */
1553 if (nbytes > (state->segcxt.ws_segsize - startoff))
1554 segbytes = state->segcxt.ws_segsize - startoff;
1555 else
1556 segbytes = nbytes;
1557
1558#ifndef FRONTEND
1559 /* Measure I/O timing when reading segment */
1561
1562 pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
1563#endif
1564
1565 /* Reset errno first; eases reporting non-errno-affecting errors */
1566 errno = 0;
1567 readbytes = pg_pread(state->seg.ws_file, p, segbytes, (off_t) startoff);
1568
1569#ifndef FRONTEND
1571
1573 io_start, 1, readbytes);
1574#endif
1575
1576 if (readbytes <= 0)
1577 {
1578 errinfo->wre_errno = errno;
1579 errinfo->wre_req = segbytes;
1580 errinfo->wre_read = readbytes;
1581 errinfo->wre_off = startoff;
1582 errinfo->wre_seg = state->seg;
1583 return false;
1584 }
1585
1586 /* Update state for read */
1587 recptr += readbytes;
1588 nbytes -= readbytes;
1589 p += readbytes;
1590 }
1591
1592 return true;
1593}
size_t Size
Definition: c.h:576
static char * buf
Definition: pg_test_fsync.c:72
@ IOOBJECT_WAL
Definition: pgstat.h:276
@ IOCONTEXT_NORMAL
Definition: pgstat.h:286
@ IOOP_READ
Definition: pgstat.h:312
instr_time pgstat_prepare_io_time(bool track_io_guc)
Definition: pgstat_io.c:90
void pgstat_count_io_op_time(IOObject io_object, IOContext io_context, IOOp io_op, instr_time start_time, uint32 cnt, uint64 bytes)
Definition: pgstat_io.c:121
#define pg_pread
Definition: port.h:226
WALOpenSegment wre_seg
Definition: xlogreader.h:388
static void pgstat_report_wait_start(uint32 wait_event_info)
Definition: wait_event.h:85
static void pgstat_report_wait_end(void)
Definition: wait_event.h:101
bool track_wal_io_timing
Definition: xlog.c:137
#define XLByteInSeg(xlrp, logSegNo, wal_segsz_bytes)

References Assert(), buf, IOCONTEXT_NORMAL, IOOBJECT_WAL, IOOP_READ, pg_pread, pgstat_count_io_op_time(), pgstat_prepare_io_time(), pgstat_report_wait_end(), pgstat_report_wait_start(), track_wal_io_timing, WALReadError::wre_errno, WALReadError::wre_off, WALReadError::wre_read, WALReadError::wre_req, WALReadError::wre_seg, XLByteInSeg, XLByteToSeg, and XLogSegmentOffset.

Referenced by logical_read_xlog_page(), read_local_xlog_page_guts(), summarizer_read_local_xlog_page(), WALDumpReadPage(), and XLogSendPhysical().

◆ XLogBeginRead()

void XLogBeginRead ( XLogReaderState state,
XLogRecPtr  RecPtr 
)

Definition at line 232 of file xlogreader.c.

233{
234 Assert(!XLogRecPtrIsInvalid(RecPtr));
235
237
238 /* Begin at the passed-in record pointer. */
239 state->EndRecPtr = RecPtr;
240 state->NextRecPtr = RecPtr;
241 state->ReadRecPtr = InvalidXLogRecPtr;
242 state->DecodeRecPtr = InvalidXLogRecPtr;
243}
#define XLogRecPtrIsInvalid(r)
Definition: xlogdefs.h:29
#define InvalidXLogRecPtr
Definition: xlogdefs.h:28
static void ResetDecoder(XLogReaderState *state)
Definition: xlogreader.c:1605

References Assert(), InvalidXLogRecPtr, ResetDecoder(), and XLogRecPtrIsInvalid.

Referenced by DecodingContextFindStartpoint(), extractPageMap(), findLastCheckpoint(), LogicalReplicationSlotHasPendingWal(), LogicalSlotAdvanceAndCheckSnapState(), pg_logical_slot_get_changes_guts(), readOneRecord(), StartLogicalReplication(), SummarizeWAL(), XLogFindNextRecord(), XLogPrefetcherBeginRead(), and XlogReadTwoPhaseData().

◆ XLogDecodeNextRecord()

static XLogPageReadResult XLogDecodeNextRecord ( XLogReaderState state,
bool  nonblocking 
)
static

Definition at line 529 of file xlogreader.c.

530{
531 XLogRecPtr RecPtr;
532 XLogRecord *record;
533 XLogRecPtr targetPagePtr;
534 bool randAccess;
535 uint32 len,
536 total_len;
537 uint32 targetRecOff;
538 uint32 pageHeaderSize;
539 bool assembled;
540 bool gotheader;
541 int readOff;
542 DecodedXLogRecord *decoded;
543 char *errormsg; /* not used */
544
545 /*
546 * randAccess indicates whether to verify the previous-record pointer of
547 * the record we're reading. We only do this if we're reading
548 * sequentially, which is what we initially assume.
549 */
550 randAccess = false;
551
552 /* reset error state */
553 state->errormsg_buf[0] = '\0';
554 decoded = NULL;
555
556 state->abortedRecPtr = InvalidXLogRecPtr;
557 state->missingContrecPtr = InvalidXLogRecPtr;
558
559 RecPtr = state->NextRecPtr;
560
561 if (state->DecodeRecPtr != InvalidXLogRecPtr)
562 {
563 /* read the record after the one we just read */
564
565 /*
566 * NextRecPtr is pointing to end+1 of the previous WAL record. If
567 * we're at a page boundary, no more records can fit on the current
568 * page. We must skip over the page header, but we can't do that until
569 * we've read in the page, since the header size is variable.
570 */
571 }
572 else
573 {
574 /*
575 * Caller supplied a position to start at.
576 *
577 * In this case, NextRecPtr should already be pointing either to a
578 * valid record starting position or alternatively to the beginning of
579 * a page. See the header comments for XLogBeginRead.
580 */
581 Assert(RecPtr % XLOG_BLCKSZ == 0 || XRecOffIsValid(RecPtr));
582 randAccess = true;
583 }
584
585restart:
586 state->nonblocking = nonblocking;
587 state->currRecPtr = RecPtr;
588 assembled = false;
589
590 targetPagePtr = RecPtr - (RecPtr % XLOG_BLCKSZ);
591 targetRecOff = RecPtr % XLOG_BLCKSZ;
592
593 /*
594 * Read the page containing the record into state->readBuf. Request enough
595 * byte to cover the whole record header, or at least the part of it that
596 * fits on the same page.
597 */
598 readOff = ReadPageInternal(state, targetPagePtr,
599 Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ));
601 return XLREAD_WOULDBLOCK;
602 else if (readOff < 0)
603 goto err;
604
605 /*
606 * ReadPageInternal always returns at least the page header, so we can
607 * examine it now.
608 */
609 pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
610 if (targetRecOff == 0)
611 {
612 /*
613 * At page start, so skip over page header.
614 */
615 RecPtr += pageHeaderSize;
616 targetRecOff = pageHeaderSize;
617 }
618 else if (targetRecOff < pageHeaderSize)
619 {
620 report_invalid_record(state, "invalid record offset at %X/%X: expected at least %u, got %u",
621 LSN_FORMAT_ARGS(RecPtr),
622 pageHeaderSize, targetRecOff);
623 goto err;
624 }
625
626 if ((((XLogPageHeader) state->readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
627 targetRecOff == pageHeaderSize)
628 {
629 report_invalid_record(state, "contrecord is requested by %X/%X",
630 LSN_FORMAT_ARGS(RecPtr));
631 goto err;
632 }
633
634 /* ReadPageInternal has verified the page header */
635 Assert(pageHeaderSize <= readOff);
636
637 /*
638 * Read the record length.
639 *
640 * NB: Even though we use an XLogRecord pointer here, the whole record
641 * header might not fit on this page. xl_tot_len is the first field of the
642 * struct, so it must be on this page (the records are MAXALIGNed), but we
643 * cannot access any other fields until we've verified that we got the
644 * whole header.
645 */
646 record = (XLogRecord *) (state->readBuf + RecPtr % XLOG_BLCKSZ);
647 total_len = record->xl_tot_len;
648
649 /*
650 * If the whole record header is on this page, validate it immediately.
651 * Otherwise do just a basic sanity check on xl_tot_len, and validate the
652 * rest of the header after reading it from the next page. The xl_tot_len
653 * check is necessary here to ensure that we enter the "Need to reassemble
654 * record" code path below; otherwise we might fail to apply
655 * ValidXLogRecordHeader at all.
656 */
657 if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord)
658 {
659 if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr, record,
660 randAccess))
661 goto err;
662 gotheader = true;
663 }
664 else
665 {
666 /* There may be no next page if it's too small. */
667 if (total_len < SizeOfXLogRecord)
668 {
670 "invalid record length at %X/%X: expected at least %u, got %u",
671 LSN_FORMAT_ARGS(RecPtr),
672 (uint32) SizeOfXLogRecord, total_len);
673 goto err;
674 }
675 /* We'll validate the header once we have the next page. */
676 gotheader = false;
677 }
678
679 /*
680 * Try to find space to decode this record, if we can do so without
681 * calling palloc. If we can't, we'll try again below after we've
682 * validated that total_len isn't garbage bytes from a recycled WAL page.
683 */
684 decoded = XLogReadRecordAlloc(state,
685 total_len,
686 false /* allow_oversized */ );
687 if (decoded == NULL && nonblocking)
688 {
689 /*
690 * There is no space in the circular decode buffer, and the caller is
691 * only reading ahead. The caller should consume existing records to
692 * make space.
693 */
694 return XLREAD_WOULDBLOCK;
695 }
696
697 len = XLOG_BLCKSZ - RecPtr % XLOG_BLCKSZ;
698 if (total_len > len)
699 {
700 /* Need to reassemble record */
701 char *contdata;
702 XLogPageHeader pageHeader;
703 char *buffer;
704 uint32 gotlen;
705
706 assembled = true;
707
708 /*
709 * We always have space for a couple of pages, enough to validate a
710 * boundary-spanning record header.
711 */
712 Assert(state->readRecordBufSize >= XLOG_BLCKSZ * 2);
713 Assert(state->readRecordBufSize >= len);
714
715 /* Copy the first fragment of the record from the first page. */
716 memcpy(state->readRecordBuf,
717 state->readBuf + RecPtr % XLOG_BLCKSZ, len);
718 buffer = state->readRecordBuf + len;
719 gotlen = len;
720
721 do
722 {
723 /* Calculate pointer to beginning of next page */
724 targetPagePtr += XLOG_BLCKSZ;
725
726 /* Wait for the next page to become available */
727 readOff = ReadPageInternal(state, targetPagePtr,
728 Min(total_len - gotlen + SizeOfXLogShortPHD,
729 XLOG_BLCKSZ));
730
732 return XLREAD_WOULDBLOCK;
733 else if (readOff < 0)
734 goto err;
735
737
738 pageHeader = (XLogPageHeader) state->readBuf;
739
740 /*
741 * If we were expecting a continuation record and got an
742 * "overwrite contrecord" flag, that means the continuation record
743 * was overwritten with a different record. Restart the read by
744 * assuming the address to read is the location where we found
745 * this flag; but keep track of the LSN of the record we were
746 * reading, for later verification.
747 */
749 {
750 state->overwrittenRecPtr = RecPtr;
751 RecPtr = targetPagePtr;
752 goto restart;
753 }
754
755 /* Check that the continuation on next page looks valid */
756 if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD))
757 {
759 "there is no contrecord flag at %X/%X",
760 LSN_FORMAT_ARGS(RecPtr));
761 goto err;
762 }
763
764 /*
765 * Cross-check that xlp_rem_len agrees with how much of the record
766 * we expect there to be left.
767 */
768 if (pageHeader->xlp_rem_len == 0 ||
769 total_len != (pageHeader->xlp_rem_len + gotlen))
770 {
772 "invalid contrecord length %u (expected %lld) at %X/%X",
773 pageHeader->xlp_rem_len,
774 ((long long) total_len) - gotlen,
775 LSN_FORMAT_ARGS(RecPtr));
776 goto err;
777 }
778
779 /* Append the continuation from this page to the buffer */
780 pageHeaderSize = XLogPageHeaderSize(pageHeader);
781
782 if (readOff < pageHeaderSize)
783 readOff = ReadPageInternal(state, targetPagePtr,
784 pageHeaderSize);
785
786 Assert(pageHeaderSize <= readOff);
787
788 contdata = (char *) state->readBuf + pageHeaderSize;
789 len = XLOG_BLCKSZ - pageHeaderSize;
790 if (pageHeader->xlp_rem_len < len)
791 len = pageHeader->xlp_rem_len;
792
793 if (readOff < pageHeaderSize + len)
794 readOff = ReadPageInternal(state, targetPagePtr,
795 pageHeaderSize + len);
796
797 memcpy(buffer, contdata, len);
798 buffer += len;
799 gotlen += len;
800
801 /* If we just reassembled the record header, validate it. */
802 if (!gotheader)
803 {
804 record = (XLogRecord *) state->readRecordBuf;
805 if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr,
806 record, randAccess))
807 goto err;
808 gotheader = true;
809 }
810
811 /*
812 * We might need a bigger buffer. We have validated the record
813 * header, in the case that it split over a page boundary. We've
814 * also cross-checked total_len against xlp_rem_len on the second
815 * page, and verified xlp_pageaddr on both.
816 */
817 if (total_len > state->readRecordBufSize)
818 {
819 char save_copy[XLOG_BLCKSZ * 2];
820
821 /*
822 * Save and restore the data we already had. It can't be more
823 * than two pages.
824 */
825 Assert(gotlen <= lengthof(save_copy));
826 Assert(gotlen <= state->readRecordBufSize);
827 memcpy(save_copy, state->readRecordBuf, gotlen);
828 allocate_recordbuf(state, total_len);
829 memcpy(state->readRecordBuf, save_copy, gotlen);
830 buffer = state->readRecordBuf + gotlen;
831 }
832 } while (gotlen < total_len);
833 Assert(gotheader);
834
835 record = (XLogRecord *) state->readRecordBuf;
836 if (!ValidXLogRecord(state, record, RecPtr))
837 goto err;
838
839 pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
840 state->DecodeRecPtr = RecPtr;
841 state->NextRecPtr = targetPagePtr + pageHeaderSize
842 + MAXALIGN(pageHeader->xlp_rem_len);
843 }
844 else
845 {
846 /* Wait for the record data to become available */
847 readOff = ReadPageInternal(state, targetPagePtr,
848 Min(targetRecOff + total_len, XLOG_BLCKSZ));
850 return XLREAD_WOULDBLOCK;
851 else if (readOff < 0)
852 goto err;
853
854 /* Record does not cross a page boundary */
855 if (!ValidXLogRecord(state, record, RecPtr))
856 goto err;
857
858 state->NextRecPtr = RecPtr + MAXALIGN(total_len);
859
860 state->DecodeRecPtr = RecPtr;
861 }
862
863 /*
864 * Special processing if it's an XLOG SWITCH record
865 */
866 if (record->xl_rmid == RM_XLOG_ID &&
867 (record->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH)
868 {
869 /* Pretend it extends to end of segment */
870 state->NextRecPtr += state->segcxt.ws_segsize - 1;
871 state->NextRecPtr -= XLogSegmentOffset(state->NextRecPtr, state->segcxt.ws_segsize);
872 }
873
874 /*
875 * If we got here without a DecodedXLogRecord, it means we needed to
876 * validate total_len before trusting it, but by now we've done that.
877 */
878 if (decoded == NULL)
879 {
880 Assert(!nonblocking);
881 decoded = XLogReadRecordAlloc(state,
882 total_len,
883 true /* allow_oversized */ );
884 /* allocation should always happen under allow_oversized */
885 Assert(decoded != NULL);
886 }
887
888 if (DecodeXLogRecord(state, decoded, record, RecPtr, &errormsg))
889 {
890 /* Record the location of the next record. */
891 decoded->next_lsn = state->NextRecPtr;
892
893 /*
894 * If it's in the decode buffer, mark the decode buffer space as
895 * occupied.
896 */
897 if (!decoded->oversized)
898 {
899 /* The new decode buffer head must be MAXALIGNed. */
900 Assert(decoded->size == MAXALIGN(decoded->size));
901 if ((char *) decoded == state->decode_buffer)
902 state->decode_buffer_tail = state->decode_buffer + decoded->size;
903 else
904 state->decode_buffer_tail += decoded->size;
905 }
906
907 /* Insert it into the queue of decoded records. */
908 Assert(state->decode_queue_tail != decoded);
909 if (state->decode_queue_tail)
910 state->decode_queue_tail->next = decoded;
911 state->decode_queue_tail = decoded;
912 if (!state->decode_queue_head)
913 state->decode_queue_head = decoded;
914 return XLREAD_SUCCESS;
915 }
916
917err:
918 if (assembled)
919 {
920 /*
921 * We get here when a record that spans multiple pages needs to be
922 * assembled, but something went wrong -- perhaps a contrecord piece
923 * was lost. If caller is WAL replay, it will know where the aborted
924 * record was and where to direct followup WAL to be written, marking
925 * the next piece with XLP_FIRST_IS_OVERWRITE_CONTRECORD, which will
926 * in turn signal downstream WAL consumers that the broken WAL record
927 * is to be ignored.
928 */
929 state->abortedRecPtr = RecPtr;
930 state->missingContrecPtr = targetPagePtr;
931
932 /*
933 * If we got here without reporting an error, make sure an error is
934 * queued so that XLogPrefetcherReadRecord() doesn't bring us back a
935 * second time and clobber the above state.
936 */
937 state->errormsg_deferred = true;
938 }
939
940 if (decoded && decoded->oversized)
941 pfree(decoded);
942
943 /*
944 * Invalidate the read state. We might read from a different source after
945 * failure.
946 */
948
949 /*
950 * If an error was written to errormsg_buf, it'll be returned to the
951 * caller of XLogReadRecord() after all successfully decoded records from
952 * the read queue.
953 */
954
955 return XLREAD_FAIL;
956}
#define Min(x, y)
Definition: c.h:975
#define lengthof(array)
Definition: c.h:759
#define XLOG_SWITCH
Definition: pg_control.h:72
const void size_t len
XLogRecPtr next_lsn
Definition: xlogreader.h:165
uint8 xl_info
Definition: xlogrecord.h:46
struct state * next
Definition: regguts.h:332
#define XLP_FIRST_IS_CONTRECORD
Definition: xlog_internal.h:74
#define XLP_FIRST_IS_OVERWRITE_CONTRECORD
Definition: xlog_internal.h:80
#define XRecOffIsValid(xlrp)
static int ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
Definition: xlogreader.c:1001
static void static void allocate_recordbuf(XLogReaderState *state, uint32 reclength)
Definition: xlogreader.c:191
bool DecodeXLogRecord(XLogReaderState *state, DecodedXLogRecord *decoded, XLogRecord *record, XLogRecPtr lsn, char **errormsg)
Definition: xlogreader.c:1672
static bool ValidXLogRecord(XLogReaderState *state, XLogRecord *record, XLogRecPtr recptr)
Definition: xlogreader.c:1194
static DecodedXLogRecord * XLogReadRecordAlloc(XLogReaderState *state, size_t xl_tot_len, bool allow_oversized)
Definition: xlogreader.c:439
static bool ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr, XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess)
Definition: xlogreader.c:1128
@ XLREAD_SUCCESS
Definition: xlogreader.h:351
#define XLR_INFO_MASK
Definition: xlogrecord.h:62
static uint32 readOff
Definition: xlogrecovery.c:233

References allocate_recordbuf(), Assert(), DecodeXLogRecord(), err(), if(), InvalidXLogRecPtr, len, lengthof, LSN_FORMAT_ARGS, MAXALIGN, Min, state::next, DecodedXLogRecord::next_lsn, DecodedXLogRecord::oversized, pfree(), readOff, ReadPageInternal(), report_invalid_record(), DecodedXLogRecord::size, SizeOfXLogRecord, SizeOfXLogShortPHD, ValidXLogRecord(), ValidXLogRecordHeader(), XLogRecord::xl_info, XLogRecord::xl_rmid, XLogRecord::xl_tot_len, XLOG_SWITCH, XLogPageHeaderSize, XLogReaderInvalReadState(), XLogReadRecordAlloc(), XLogSegmentOffset, XLP_FIRST_IS_CONTRECORD, XLP_FIRST_IS_OVERWRITE_CONTRECORD, XLogPageHeaderData::xlp_info, XLogPageHeaderData::xlp_rem_len, XLR_INFO_MASK, XLREAD_FAIL, XLREAD_SUCCESS, XLREAD_WOULDBLOCK, and XRecOffIsValid.

Referenced by XLogReadAhead().

◆ XLogFindNextRecord()

XLogRecPtr XLogFindNextRecord ( XLogReaderState state,
XLogRecPtr  RecPtr 
)

Definition at line 1384 of file xlogreader.c.

1385{
1386 XLogRecPtr tmpRecPtr;
1388 XLogPageHeader header;
1389 char *errormsg;
1390
1391 Assert(!XLogRecPtrIsInvalid(RecPtr));
1392
1393 /* Make sure ReadPageInternal() can't return XLREAD_WOULDBLOCK. */
1394 state->nonblocking = false;
1395
1396 /*
1397 * skip over potential continuation data, keeping in mind that it may span
1398 * multiple pages
1399 */
1400 tmpRecPtr = RecPtr;
1401 while (true)
1402 {
1403 XLogRecPtr targetPagePtr;
1404 int targetRecOff;
1405 uint32 pageHeaderSize;
1406 int readLen;
1407
1408 /*
1409 * Compute targetRecOff. It should typically be equal or greater than
1410 * short page-header since a valid record can't start anywhere before
1411 * that, except when caller has explicitly specified the offset that
1412 * falls somewhere there or when we are skipping multi-page
1413 * continuation record. It doesn't matter though because
1414 * ReadPageInternal() is prepared to handle that and will read at
1415 * least short page-header worth of data
1416 */
1417 targetRecOff = tmpRecPtr % XLOG_BLCKSZ;
1418
1419 /* scroll back to page boundary */
1420 targetPagePtr = tmpRecPtr - targetRecOff;
1421
1422 /* Read the page containing the record */
1423 readLen = ReadPageInternal(state, targetPagePtr, targetRecOff);
1424 if (readLen < 0)
1425 goto err;
1426
1427 header = (XLogPageHeader) state->readBuf;
1428
1429 pageHeaderSize = XLogPageHeaderSize(header);
1430
1431 /* make sure we have enough data for the page header */
1432 readLen = ReadPageInternal(state, targetPagePtr, pageHeaderSize);
1433 if (readLen < 0)
1434 goto err;
1435
1436 /* skip over potential continuation data */
1437 if (header->xlp_info & XLP_FIRST_IS_CONTRECORD)
1438 {
1439 /*
1440 * If the length of the remaining continuation data is more than
1441 * what can fit in this page, the continuation record crosses over
1442 * this page. Read the next page and try again. xlp_rem_len in the
1443 * next page header will contain the remaining length of the
1444 * continuation data
1445 *
1446 * Note that record headers are MAXALIGN'ed
1447 */
1448 if (MAXALIGN(header->xlp_rem_len) >= (XLOG_BLCKSZ - pageHeaderSize))
1449 tmpRecPtr = targetPagePtr + XLOG_BLCKSZ;
1450 else
1451 {
1452 /*
1453 * The previous continuation record ends in this page. Set
1454 * tmpRecPtr to point to the first valid record
1455 */
1456 tmpRecPtr = targetPagePtr + pageHeaderSize
1457 + MAXALIGN(header->xlp_rem_len);
1458 break;
1459 }
1460 }
1461 else
1462 {
1463 tmpRecPtr = targetPagePtr + pageHeaderSize;
1464 break;
1465 }
1466 }
1467
1468 /*
1469 * we know now that tmpRecPtr is an address pointing to a valid XLogRecord
1470 * because either we're at the first record after the beginning of a page
1471 * or we just jumped over the remaining data of a continuation.
1472 */
1473 XLogBeginRead(state, tmpRecPtr);
1474 while (XLogReadRecord(state, &errormsg) != NULL)
1475 {
1476 /* past the record we've found, break out */
1477 if (RecPtr <= state->ReadRecPtr)
1478 {
1479 /* Rewind the reader to the beginning of the last record. */
1480 found = state->ReadRecPtr;
1481 XLogBeginRead(state, found);
1482 return found;
1483 }
1484 }
1485
1486err:
1488
1489 return InvalidXLogRecPtr;
1490}
XLogRecord * XLogReadRecord(XLogReaderState *state, char **errormsg)
Definition: xlogreader.c:390
void XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr)
Definition: xlogreader.c:232

References Assert(), err(), InvalidXLogRecPtr, MAXALIGN, readLen, ReadPageInternal(), XLogBeginRead(), XLogPageHeaderSize, XLogReaderInvalReadState(), XLogReadRecord(), XLogRecPtrIsInvalid, XLP_FIRST_IS_CONTRECORD, XLogPageHeaderData::xlp_info, and XLogPageHeaderData::xlp_rem_len.

Referenced by InitXLogReaderState(), main(), and SummarizeWAL().

◆ XLogNextRecord()

DecodedXLogRecord * XLogNextRecord ( XLogReaderState state,
char **  errormsg 
)

Definition at line 326 of file xlogreader.c.

327{
328 /* Release the last record returned by XLogNextRecord(). */
330
331 if (state->decode_queue_head == NULL)
332 {
333 *errormsg = NULL;
334 if (state->errormsg_deferred)
335 {
336 if (state->errormsg_buf[0] != '\0')
337 *errormsg = state->errormsg_buf;
338 state->errormsg_deferred = false;
339 }
340
341 /*
342 * state->EndRecPtr is expected to have been set by the last call to
343 * XLogBeginRead() or XLogNextRecord(), and is the location of the
344 * error.
345 */
346 Assert(!XLogRecPtrIsInvalid(state->EndRecPtr));
347
348 return NULL;
349 }
350
351 /*
352 * Record this as the most recent record returned, so that we'll release
353 * it next time. This also exposes it to the traditional
354 * XLogRecXXX(xlogreader) macros, which work with the decoder rather than
355 * the record for historical reasons.
356 */
357 state->record = state->decode_queue_head;
358
359 /*
360 * Update the pointers to the beginning and one-past-the-end of this
361 * record, again for the benefit of historical code that expected the
362 * decoder to track this rather than accessing these fields of the record
363 * itself.
364 */
365 state->ReadRecPtr = state->record->lsn;
366 state->EndRecPtr = state->record->next_lsn;
367
368 *errormsg = NULL;
369
370 return state->record;
371}
XLogRecPtr XLogReleasePreviousRecord(XLogReaderState *state)
Definition: xlogreader.c:250

References Assert(), XLogRecPtrIsInvalid, and XLogReleasePreviousRecord().

Referenced by XLogPrefetcherReadRecord(), and XLogReadRecord().

◆ XLogReadAhead()

DecodedXLogRecord * XLogReadAhead ( XLogReaderState state,
bool  nonblocking 
)

Definition at line 967 of file xlogreader.c.

968{
969 XLogPageReadResult result;
970
971 if (state->errormsg_deferred)
972 return NULL;
973
974 result = XLogDecodeNextRecord(state, nonblocking);
975 if (result == XLREAD_SUCCESS)
976 {
977 Assert(state->decode_queue_tail != NULL);
978 return state->decode_queue_tail;
979 }
980
981 return NULL;
982}
static XLogPageReadResult XLogDecodeNextRecord(XLogReaderState *state, bool nonblocking)
Definition: xlogreader.c:529
XLogPageReadResult
Definition: xlogreader.h:350

References Assert(), XLogDecodeNextRecord(), and XLREAD_SUCCESS.

Referenced by XLogPrefetcherNextBlock(), and XLogReadRecord().

◆ XLogReaderAllocate()

XLogReaderState * XLogReaderAllocate ( int  wal_segment_size,
const char *  waldir,
XLogReaderRoutine routine,
void *  private_data 
)

Definition at line 107 of file xlogreader.c.

109{
111
115 if (!state)
116 return NULL;
117
118 /* initialize caller-provided support functions */
119 state->routine = *routine;
120
121 /*
122 * Permanently allocate readBuf. We do it this way, rather than just
123 * making a static array, for two reasons: (1) no need to waste the
124 * storage in most instantiations of the backend; (2) a static char array
125 * isn't guaranteed to have any particular alignment, whereas
126 * palloc_extended() will provide MAXALIGN'd storage.
127 */
128 state->readBuf = (char *) palloc_extended(XLOG_BLCKSZ,
130 if (!state->readBuf)
131 {
132 pfree(state);
133 return NULL;
134 }
135
136 /* Initialize segment info. */
138 waldir);
139
140 /* system_identifier initialized to zeroes above */
141 state->private_data = private_data;
142 /* ReadRecPtr, EndRecPtr and readLen initialized to zeroes above */
143 state->errormsg_buf = palloc_extended(MAX_ERRORMSG_LEN + 1,
145 if (!state->errormsg_buf)
146 {
147 pfree(state->readBuf);
148 pfree(state);
149 return NULL;
150 }
151 state->errormsg_buf[0] = '\0';
152
153 /*
154 * Allocate an initial readRecordBuf of minimal size, which can later be
155 * enlarged if necessary.
156 */
158 return state;
159}
#define MCXT_ALLOC_ZERO
Definition: fe_memutils.h:30
#define MCXT_ALLOC_NO_OOM
Definition: fe_memutils.h:29
void * palloc_extended(Size size, int flags)
Definition: mcxt.c:1369
int wal_segment_size
Definition: xlog.c:143
static void WALOpenSegmentInit(WALOpenSegment *seg, WALSegmentContext *segcxt, int segsize, const char *waldir)
Definition: xlogreader.c:208

References allocate_recordbuf(), MAX_ERRORMSG_LEN, MCXT_ALLOC_NO_OOM, MCXT_ALLOC_ZERO, palloc_extended(), pfree(), wal_segment_size, and WALOpenSegmentInit().

Referenced by extractPageMap(), findLastCheckpoint(), InitWalRecovery(), InitXLogReaderState(), main(), readOneRecord(), StartReplication(), StartupDecodingContext(), SummarizeWAL(), XLogInsertRecord(), and XlogReadTwoPhaseData().

◆ XLogReaderFree()

void XLogReaderFree ( XLogReaderState state)

Definition at line 162 of file xlogreader.c.

163{
164 if (state->seg.ws_file != -1)
165 state->routine.segment_close(state);
166
167 if (state->decode_buffer && state->free_decode_buffer)
168 pfree(state->decode_buffer);
169
170 pfree(state->errormsg_buf);
171 if (state->readRecordBuf)
172 pfree(state->readRecordBuf);
173 pfree(state->readBuf);
174 pfree(state);
175}

References pfree().

Referenced by extractPageMap(), findLastCheckpoint(), FreeDecodingContext(), GetWALRecordsInfo(), main(), pg_get_wal_block_info(), pg_get_wal_record_info(), readOneRecord(), ShutdownWalRecovery(), SummarizeWAL(), and XlogReadTwoPhaseData().

◆ XLogReaderInvalReadState()

static void XLogReaderInvalReadState ( XLogReaderState state)
static

Definition at line 1114 of file xlogreader.c.

1115{
1116 state->seg.ws_segno = 0;
1117 state->segoff = 0;
1118 state->readLen = 0;
1119}

Referenced by ReadPageInternal(), XLogDecodeNextRecord(), and XLogFindNextRecord().

◆ XLogReaderResetError()

void XLogReaderResetError ( XLogReaderState state)

Definition at line 1366 of file xlogreader.c.

1367{
1368 state->errormsg_buf[0] = '\0';
1369 state->errormsg_deferred = false;
1370}

Referenced by XLogPageRead().

◆ XLogReaderSetDecodeBuffer()

void XLogReaderSetDecodeBuffer ( XLogReaderState state,
void *  buffer,
size_t  size 
)

Definition at line 91 of file xlogreader.c.

92{
93 Assert(state->decode_buffer == NULL);
94
95 state->decode_buffer = buffer;
96 state->decode_buffer_size = size;
97 state->decode_buffer_tail = buffer;
98 state->decode_buffer_head = buffer;
99}

References Assert().

Referenced by InitWalRecovery().

◆ XLogReaderValidatePageHeader()

bool XLogReaderValidatePageHeader ( XLogReaderState state,
XLogRecPtr  recptr,
char *  phdr 
)

Definition at line 1225 of file xlogreader.c.

1227{
1228 XLogSegNo segno;
1229 int32 offset;
1230 XLogPageHeader hdr = (XLogPageHeader) phdr;
1231
1232 Assert((recptr % XLOG_BLCKSZ) == 0);
1233
1234 XLByteToSeg(recptr, segno, state->segcxt.ws_segsize);
1235 offset = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
1236
1237 if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
1238 {
1239 char fname[MAXFNAMELEN];
1240
1241 XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1242
1244 "invalid magic number %04X in WAL segment %s, LSN %X/%X, offset %u",
1245 hdr->xlp_magic,
1246 fname,
1247 LSN_FORMAT_ARGS(recptr),
1248 offset);
1249 return false;
1250 }
1251
1252 if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0)
1253 {
1254 char fname[MAXFNAMELEN];
1255
1256 XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1257
1259 "invalid info bits %04X in WAL segment %s, LSN %X/%X, offset %u",
1260 hdr->xlp_info,
1261 fname,
1262 LSN_FORMAT_ARGS(recptr),
1263 offset);
1264 return false;
1265 }
1266
1267 if (hdr->xlp_info & XLP_LONG_HEADER)
1268 {
1269 XLogLongPageHeader longhdr = (XLogLongPageHeader) hdr;
1270
1271 if (state->system_identifier &&
1272 longhdr->xlp_sysid != state->system_identifier)
1273 {
1275 "WAL file is from different database system: WAL file database system identifier is %llu, pg_control database system identifier is %llu",
1276 (unsigned long long) longhdr->xlp_sysid,
1277 (unsigned long long) state->system_identifier);
1278 return false;
1279 }
1280 else if (longhdr->xlp_seg_size != state->segcxt.ws_segsize)
1281 {
1283 "WAL file is from different database system: incorrect segment size in page header");
1284 return false;
1285 }
1286 else if (longhdr->xlp_xlog_blcksz != XLOG_BLCKSZ)
1287 {
1289 "WAL file is from different database system: incorrect XLOG_BLCKSZ in page header");
1290 return false;
1291 }
1292 }
1293 else if (offset == 0)
1294 {
1295 char fname[MAXFNAMELEN];
1296
1297 XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1298
1299 /* hmm, first page of file doesn't have a long header? */
1301 "invalid info bits %04X in WAL segment %s, LSN %X/%X, offset %u",
1302 hdr->xlp_info,
1303 fname,
1304 LSN_FORMAT_ARGS(recptr),
1305 offset);
1306 return false;
1307 }
1308
1309 /*
1310 * Check that the address on the page agrees with what we expected. This
1311 * check typically fails when an old WAL segment is recycled, and hasn't
1312 * yet been overwritten with new data yet.
1313 */
1314 if (hdr->xlp_pageaddr != recptr)
1315 {
1316 char fname[MAXFNAMELEN];
1317
1318 XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1319
1321 "unexpected pageaddr %X/%X in WAL segment %s, LSN %X/%X, offset %u",
1323 fname,
1324 LSN_FORMAT_ARGS(recptr),
1325 offset);
1326 return false;
1327 }
1328
1329 /*
1330 * Since child timelines are always assigned a TLI greater than their
1331 * immediate parent's TLI, we should never see TLI go backwards across
1332 * successive pages of a consistent WAL sequence.
1333 *
1334 * Sometimes we re-read a segment that's already been (partially) read. So
1335 * we only verify TLIs for pages that are later than the last remembered
1336 * LSN.
1337 */
1338 if (recptr > state->latestPagePtr)
1339 {
1340 if (hdr->xlp_tli < state->latestPageTLI)
1341 {
1342 char fname[MAXFNAMELEN];
1343
1344 XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1345
1347 "out-of-sequence timeline ID %u (after %u) in WAL segment %s, LSN %X/%X, offset %u",
1348 hdr->xlp_tli,
1349 state->latestPageTLI,
1350 fname,
1351 LSN_FORMAT_ARGS(recptr),
1352 offset);
1353 return false;
1354 }
1355 }
1356 state->latestPagePtr = recptr;
1357 state->latestPageTLI = hdr->xlp_tli;
1358
1359 return true;
1360}
int32_t int32
Definition: c.h:498
TimeLineID xlp_tli
Definition: xlog_internal.h:40
XLogRecPtr xlp_pageaddr
Definition: xlog_internal.h:41
XLogLongPageHeaderData * XLogLongPageHeader
Definition: xlog_internal.h:71
#define MAXFNAMELEN
#define XLP_LONG_HEADER
Definition: xlog_internal.h:76
#define XLP_ALL_FLAGS
Definition: xlog_internal.h:82
#define XLOG_PAGE_MAGIC
Definition: xlog_internal.h:34
static void XLogFileName(char *fname, TimeLineID tli, XLogSegNo logSegNo, int wal_segsz_bytes)

References Assert(), LSN_FORMAT_ARGS, MAXFNAMELEN, report_invalid_record(), XLByteToSeg, XLOG_PAGE_MAGIC, XLogFileName(), XLogSegmentOffset, XLP_ALL_FLAGS, XLogPageHeaderData::xlp_info, XLP_LONG_HEADER, XLogPageHeaderData::xlp_magic, XLogPageHeaderData::xlp_pageaddr, XLogLongPageHeaderData::xlp_seg_size, XLogLongPageHeaderData::xlp_sysid, XLogPageHeaderData::xlp_tli, and XLogLongPageHeaderData::xlp_xlog_blcksz.

Referenced by ReadPageInternal(), and XLogPageRead().

◆ XLogReadRecord()

XLogRecord * XLogReadRecord ( XLogReaderState state,
char **  errormsg 
)

Definition at line 390 of file xlogreader.c.

391{
392 DecodedXLogRecord *decoded;
393
394 /*
395 * Release last returned record, if there is one. We need to do this so
396 * that we can check for empty decode queue accurately.
397 */
399
400 /*
401 * Call XLogReadAhead() in blocking mode to make sure there is something
402 * in the queue, though we don't use the result.
403 */
405 XLogReadAhead(state, false /* nonblocking */ );
406
407 /* Consume the head record or error. */
408 decoded = XLogNextRecord(state, errormsg);
409 if (decoded)
410 {
411 /*
412 * This function returns a pointer to the record's header, not the
413 * actual decoded record. The caller will access the decoded record
414 * through the XLogRecGetXXX() macros, which reach the decoded
415 * recorded as xlogreader->record.
416 */
417 Assert(state->record == decoded);
418 return &decoded->header;
419 }
420
421 return NULL;
422}
DecodedXLogRecord * XLogReadAhead(XLogReaderState *state, bool nonblocking)
Definition: xlogreader.c:967
DecodedXLogRecord * XLogNextRecord(XLogReaderState *state, char **errormsg)
Definition: xlogreader.c:326
static bool XLogReaderHasQueuedRecordOrError(XLogReaderState *state)
Definition: xlogreader.h:325

References Assert(), DecodedXLogRecord::header, XLogNextRecord(), XLogReadAhead(), XLogReaderHasQueuedRecordOrError(), and XLogReleasePreviousRecord().

Referenced by DecodingContextFindStartpoint(), extractPageMap(), findLastCheckpoint(), LogicalReplicationSlotHasPendingWal(), LogicalSlotAdvanceAndCheckSnapState(), main(), pg_logical_slot_get_changes_guts(), ReadNextXLogRecord(), readOneRecord(), SummarizeWAL(), XLogFindNextRecord(), XlogReadTwoPhaseData(), and XLogSendLogical().

◆ XLogReadRecordAlloc()

static DecodedXLogRecord * XLogReadRecordAlloc ( XLogReaderState state,
size_t  xl_tot_len,
bool  allow_oversized 
)
static

Definition at line 439 of file xlogreader.c.

440{
441 size_t required_space = DecodeXLogRecordRequiredSpace(xl_tot_len);
442 DecodedXLogRecord *decoded = NULL;
443
444 /* Allocate a circular decode buffer if we don't have one already. */
445 if (unlikely(state->decode_buffer == NULL))
446 {
447 if (state->decode_buffer_size == 0)
448 state->decode_buffer_size = DEFAULT_DECODE_BUFFER_SIZE;
449 state->decode_buffer = palloc(state->decode_buffer_size);
450 state->decode_buffer_head = state->decode_buffer;
451 state->decode_buffer_tail = state->decode_buffer;
452 state->free_decode_buffer = true;
453 }
454
455 /* Try to allocate space in the circular decode buffer. */
456 if (state->decode_buffer_tail >= state->decode_buffer_head)
457 {
458 /* Empty, or tail is to the right of head. */
459 if (required_space <=
460 state->decode_buffer_size -
461 (state->decode_buffer_tail - state->decode_buffer))
462 {
463 /*-
464 * There is space between tail and end.
465 *
466 * +-----+--------------------+-----+
467 * | |////////////////////|here!|
468 * +-----+--------------------+-----+
469 * ^ ^
470 * | |
471 * h t
472 */
473 decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
474 decoded->oversized = false;
475 return decoded;
476 }
477 else if (required_space <
478 state->decode_buffer_head - state->decode_buffer)
479 {
480 /*-
481 * There is space between start and head.
482 *
483 * +-----+--------------------+-----+
484 * |here!|////////////////////| |
485 * +-----+--------------------+-----+
486 * ^ ^
487 * | |
488 * h t
489 */
490 decoded = (DecodedXLogRecord *) state->decode_buffer;
491 decoded->oversized = false;
492 return decoded;
493 }
494 }
495 else
496 {
497 /* Tail is to the left of head. */
498 if (required_space <
499 state->decode_buffer_head - state->decode_buffer_tail)
500 {
501 /*-
502 * There is space between tail and head.
503 *
504 * +-----+--------------------+-----+
505 * |/////|here! |/////|
506 * +-----+--------------------+-----+
507 * ^ ^
508 * | |
509 * t h
510 */
511 decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
512 decoded->oversized = false;
513 return decoded;
514 }
515 }
516
517 /* Not enough space in the decode buffer. Are we allowed to allocate? */
518 if (allow_oversized)
519 {
520 decoded = palloc(required_space);
521 decoded->oversized = true;
522 return decoded;
523 }
524
525 return NULL;
526}
#define unlikely(x)
Definition: c.h:347
#define DEFAULT_DECODE_BUFFER_SIZE
Definition: xlogreader.c:65

References DecodeXLogRecordRequiredSpace(), DEFAULT_DECODE_BUFFER_SIZE, DecodedXLogRecord::oversized, palloc(), and unlikely.

Referenced by XLogDecodeNextRecord().

◆ XLogRecGetBlockData()

◆ XLogRecGetBlockTag()

void XLogRecGetBlockTag ( XLogReaderState record,
uint8  block_id,
RelFileLocator rlocator,
ForkNumber forknum,
BlockNumber blknum 
)

Definition at line 1981 of file xlogreader.c.

1984{
1985 if (!XLogRecGetBlockTagExtended(record, block_id, rlocator, forknum,
1986 blknum, NULL))
1987 {
1988#ifndef FRONTEND
1989 elog(ERROR, "could not locate backup block with ID %d in WAL record",
1990 block_id);
1991#else
1992 pg_fatal("could not locate backup block with ID %d in WAL record",
1993 block_id);
1994#endif
1995 }
1996}
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:225
#define pg_fatal(...)
bool XLogRecGetBlockTagExtended(XLogReaderState *record, uint8 block_id, RelFileLocator *rlocator, ForkNumber *forknum, BlockNumber *blknum, Buffer *prefetch_buffer)
Definition: xlogreader.c:2007

References elog, ERROR, pg_fatal, and XLogRecGetBlockTagExtended().

Referenced by brin_xlog_revmap_extend(), btree_xlog_delete(), btree_xlog_split(), DecodeDelete(), DecodeInsert(), DecodeMultiInsert(), DecodeSpecConfirm(), DecodeUpdate(), gistRedoDeleteRecord(), gistRedoPageSplitRecord(), hash_xlog_add_ovfl_page(), hash_xlog_init_bitmap_page(), hash_xlog_init_meta_page(), hash_xlog_vacuum_one_page(), heap_xlog_delete(), heap_xlog_insert(), heap_xlog_lock(), heap_xlog_lock_updated(), heap_xlog_multi_insert(), heap_xlog_prune_freeze(), heap_xlog_update(), heap_xlog_visible(), spgRedoAddLeaf(), spgRedoAddNode(), spgRedoMoveLeafs(), spgRedoPickSplit(), and spgRedoVacuumRedirect().

◆ XLogRecGetBlockTagExtended()

bool XLogRecGetBlockTagExtended ( XLogReaderState record,
uint8  block_id,
RelFileLocator rlocator,
ForkNumber forknum,
BlockNumber blknum,
Buffer prefetch_buffer 
)

Definition at line 2007 of file xlogreader.c.

2011{
2012 DecodedBkpBlock *bkpb;
2013
2014 if (!XLogRecHasBlockRef(record, block_id))
2015 return false;
2016
2017 bkpb = &record->record->blocks[block_id];
2018 if (rlocator)
2019 *rlocator = bkpb->rlocator;
2020 if (forknum)
2021 *forknum = bkpb->forknum;
2022 if (blknum)
2023 *blknum = bkpb->blkno;
2024 if (prefetch_buffer)
2025 *prefetch_buffer = bkpb->prefetch_buffer;
2026 return true;
2027}
#define XLogRecHasBlockRef(decoder, block_id)
Definition: xlogreader.h:420

References DecodedBkpBlock::blkno, DecodedXLogRecord::blocks, DecodedBkpBlock::forknum, DecodedBkpBlock::prefetch_buffer, XLogReaderState::record, DecodedBkpBlock::rlocator, and XLogRecHasBlockRef.

Referenced by btree_xlog_split(), extractPageInfo(), GetWALBlockInfo(), heap_xlog_update(), SummarizeWAL(), verifyBackupPageConsistency(), xlog_block_info(), XLogReadBufferForRedoExtended(), XLogRecGetBlockRefInfo(), XLogRecGetBlockTag(), XLogRecordMatchesRelationBlock(), and XLogRecordSaveFPWs().

◆ XLogRecGetFullXid()

FullTransactionId XLogRecGetFullXid ( XLogReaderState record)

Definition at line 2177 of file xlogreader.c.

2178{
2179 /*
2180 * This function is only safe during replay, because it depends on the
2181 * replay state. See AdvanceNextFullTransactionIdPastXid() for more.
2182 */
2184
2186 XLogRecGetXid(record));
2187}
bool IsUnderPostmaster
Definition: globals.c:119
#define AmStartupProcess()
Definition: miscadmin.h:389
FullTransactionId nextXid
Definition: transam.h:220
static FullTransactionId FullTransactionIdFromAllowableAt(FullTransactionId nextFullXid, TransactionId xid)
Definition: transam.h:381
TransamVariablesData * TransamVariables
Definition: varsup.c:34
#define XLogRecGetXid(decoder)
Definition: xlogreader.h:412

References AmStartupProcess, Assert(), FullTransactionIdFromAllowableAt(), IsUnderPostmaster, TransamVariablesData::nextXid, TransamVariables, and XLogRecGetXid.

◆ XLogReleasePreviousRecord()

XLogRecPtr XLogReleasePreviousRecord ( XLogReaderState state)

Definition at line 250 of file xlogreader.c.

251{
252 DecodedXLogRecord *record;
253 XLogRecPtr next_lsn;
254
255 if (!state->record)
256 return InvalidXLogRecPtr;
257
258 /*
259 * Remove it from the decoded record queue. It must be the oldest item
260 * decoded, decode_queue_head.
261 */
262 record = state->record;
263 next_lsn = record->next_lsn;
264 Assert(record == state->decode_queue_head);
265 state->record = NULL;
266 state->decode_queue_head = record->next;
267
268 /* It might also be the newest item decoded, decode_queue_tail. */
269 if (state->decode_queue_tail == record)
270 state->decode_queue_tail = NULL;
271
272 /* Release the space. */
273 if (unlikely(record->oversized))
274 {
275 /* It's not in the decode buffer, so free it to release space. */
276 pfree(record);
277 }
278 else
279 {
280 /* It must be the head (oldest) record in the decode buffer. */
281 Assert(state->decode_buffer_head == (char *) record);
282
283 /*
284 * We need to update head to point to the next record that is in the
285 * decode buffer, if any, being careful to skip oversized ones
286 * (they're not in the decode buffer).
287 */
288 record = record->next;
289 while (unlikely(record && record->oversized))
290 record = record->next;
291
292 if (record)
293 {
294 /* Adjust head to release space up to the next record. */
295 state->decode_buffer_head = (char *) record;
296 }
297 else
298 {
299 /*
300 * Otherwise we might as well just reset head and tail to the
301 * start of the buffer space, because we're empty. This means
302 * we'll keep overwriting the same piece of memory if we're not
303 * doing any prefetching.
304 */
305 state->decode_buffer_head = state->decode_buffer;
306 state->decode_buffer_tail = state->decode_buffer;
307 }
308 }
309
310 return next_lsn;
311}

References Assert(), InvalidXLogRecPtr, DecodedXLogRecord::next, DecodedXLogRecord::next_lsn, DecodedXLogRecord::oversized, pfree(), and unlikely.

Referenced by XLogNextRecord(), XLogPrefetcherReadRecord(), and XLogReadRecord().