#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 "miscadmin.h"
#include "pgstat.h"
#include "utils/memutils.h"

Include dependency graph for xlogreader.c:

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 bool	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 non_blocking)

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)

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

void	XLogReaderFree (XLogReaderState *state)

void	XLogBeginRead (XLogReaderState *state, XLogRecPtr RecPtr)

void	XLogReleasePreviousRecord (XLogReaderState *state)

DecodedXLogRecord *	XLogNextRecord (XLogReaderState state, char *errormsg)

XLogRecord *	XLogReadRecord (XLogReaderState state, char *errormsg)

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

DecodedXLogRecord *	XLogReadAhead (XLogReaderState *state, bool nonblocking)

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

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, RelFileNode rnode, ForkNumber forknum, BlockNumber blknum)

bool	XLogRecGetBlockTagExtended (XLogReaderState record, uint8 block_id, RelFileNode rnode, 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)

◆ DEFAULT_DECODE_BUFFER_SIZE

#define DEFAULT_DECODE_BUFFER_SIZE (64 * 1024)

Definition at line 66 of file xlogreader.c.

◆ MAX_ERRORMSG_LEN

#define MAX_ERRORMSG_LEN 1000

Definition at line 60 of file xlogreader.c.

Function Documentation

◆ allocate_recordbuf()

static bool allocate_recordbuf	(	XLogReaderState *	state,
		uint32	reclength
	)

static

Definition at line 197 of file xlogreader.c.

 {
     uint32      newSize = reclength;
  
     newSize += XLOG_BLCKSZ - (newSize % XLOG_BLCKSZ);
     newSize = Max(newSize, 5 * Max(BLCKSZ, XLOG_BLCKSZ));
  
 #ifndef FRONTEND
  
     /*
      * Note that in much unlucky circumstances, the random data read from a
      * recycled segment can cause this routine to be called with a size
      * causing a hard failure at allocation.  For a standby, this would cause
      * the instance to stop suddenly with a hard failure, preventing it to
      * retry fetching WAL from one of its sources which could allow it to move
      * on with replay without a manual restart. If the data comes from a past
      * recycled segment and is still valid, then the allocation may succeed
      * but record checks are going to fail so this would be short-lived.  If
      * the allocation fails because of a memory shortage, then this is not a
      * hard failure either per the guarantee given by MCXT_ALLOC_NO_OOM.
      */
     if (!AllocSizeIsValid(newSize))
         return false;
  
 #endif
  
     if (state->readRecordBuf)
         pfree(state->readRecordBuf);
     state->readRecordBuf =
         (char *) palloc_extended(newSize, MCXT_ALLOC_NO_OOM);
     if (state->readRecordBuf == NULL)
     {
         state->readRecordBufSize = 0;
         return false;
     }
     state->readRecordBufSize = newSize;
     return true;
 }

References AllocSizeIsValid, Max, MCXT_ALLOC_NO_OOM, palloc_extended(), and pfree().

Referenced by XLogDecodeNextRecord(), and XLogReaderAllocate().

◆ DecodeXLogRecord()

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

Definition at line 1619 of file xlogreader.c.

 {
     /*
      * read next _size bytes from record buffer, but check for overrun first.
      */
 #define COPY_HEADER_FIELD(_dst, _size)          \
     do {                                        \
         if (remaining < _size)                  \
             goto shortdata_err;                 \
         memcpy(_dst, ptr, _size);               \
         ptr += _size;                           \
         remaining -= _size;                     \
     } while(0)
  
     char       *ptr;
     char       *out;
     uint32      remaining;
     uint32      datatotal;
     RelFileNode *rnode = NULL;
     uint8       block_id;
  
     decoded->header = *record;
     decoded->lsn = lsn;
     decoded->next = NULL;
     decoded->record_origin = InvalidRepOriginId;
     decoded->toplevel_xid = InvalidTransactionId;
     decoded->main_data = NULL;
     decoded->main_data_len = 0;
     decoded->max_block_id = -1;
     ptr = (char *) record;
     ptr += SizeOfXLogRecord;
     remaining = record->xl_tot_len - SizeOfXLogRecord;
  
     /* Decode the headers */
     datatotal = 0;
     while (remaining > datatotal)
     {
         COPY_HEADER_FIELD(&block_id, sizeof(uint8));
  
         if (block_id == XLR_BLOCK_ID_DATA_SHORT)
         {
             /* XLogRecordDataHeaderShort */
             uint8       main_data_len;
  
             COPY_HEADER_FIELD(&main_data_len, sizeof(uint8));
  
             decoded->main_data_len = main_data_len;
             datatotal += main_data_len;
             break;              /* by convention, the main data fragment is
                                  * always last */
         }
         else if (block_id == XLR_BLOCK_ID_DATA_LONG)
         {
             /* XLogRecordDataHeaderLong */
             uint32      main_data_len;
  
             COPY_HEADER_FIELD(&main_data_len, sizeof(uint32));
             decoded->main_data_len = main_data_len;
             datatotal += main_data_len;
             break;              /* by convention, the main data fragment is
                                  * always last */
         }
         else if (block_id == XLR_BLOCK_ID_ORIGIN)
         {
             COPY_HEADER_FIELD(&decoded->record_origin, sizeof(RepOriginId));
         }
         else if (block_id == XLR_BLOCK_ID_TOPLEVEL_XID)
         {
             COPY_HEADER_FIELD(&decoded->toplevel_xid, sizeof(TransactionId));
         }
         else if (block_id <= XLR_MAX_BLOCK_ID)
         {
             /* XLogRecordBlockHeader */
             DecodedBkpBlock *blk;
             uint8       fork_flags;
  
             /* mark any intervening block IDs as not in use */
             for (int i = decoded->max_block_id + 1; i < block_id; ++i)
                 decoded->blocks[i].in_use = false;
  
             if (block_id <= decoded->max_block_id)
             {
                 report_invalid_record(state,
                                       "out-of-order block_id %u at %X/%X",
                                       block_id,
                                       LSN_FORMAT_ARGS(state->ReadRecPtr));
                 goto err;
             }
             decoded->max_block_id = block_id;
  
             blk = &decoded->blocks[block_id];
             blk->in_use = true;
             blk->apply_image = false;
  
             COPY_HEADER_FIELD(&fork_flags, sizeof(uint8));
             blk->forknum = fork_flags & BKPBLOCK_FORK_MASK;
             blk->flags = fork_flags;
             blk->has_image = ((fork_flags & BKPBLOCK_HAS_IMAGE) != 0);
             blk->has_data = ((fork_flags & BKPBLOCK_HAS_DATA) != 0);
  
             blk->prefetch_buffer = InvalidBuffer;
  
             COPY_HEADER_FIELD(&blk->data_len, sizeof(uint16));
             /* cross-check that the HAS_DATA flag is set iff data_length > 0 */
             if (blk->has_data && blk->data_len == 0)
             {
                 report_invalid_record(state,
                                       "BKPBLOCK_HAS_DATA set, but no data included at %X/%X",
                                       LSN_FORMAT_ARGS(state->ReadRecPtr));
                 goto err;
             }
             if (!blk->has_data && blk->data_len != 0)
             {
                 report_invalid_record(state,
                                       "BKPBLOCK_HAS_DATA not set, but data length is %u at %X/%X",
                                       (unsigned int) blk->data_len,
                                       LSN_FORMAT_ARGS(state->ReadRecPtr));
                 goto err;
             }
             datatotal += blk->data_len;
  
             if (blk->has_image)
             {
                 COPY_HEADER_FIELD(&blk->bimg_len, sizeof(uint16));
                 COPY_HEADER_FIELD(&blk->hole_offset, sizeof(uint16));
                 COPY_HEADER_FIELD(&blk->bimg_info, sizeof(uint8));
  
                 blk->apply_image = ((blk->bimg_info & BKPIMAGE_APPLY) != 0);
  
                 if (BKPIMAGE_COMPRESSED(blk->bimg_info))
                 {
                     if (blk->bimg_info & BKPIMAGE_HAS_HOLE)
                         COPY_HEADER_FIELD(&blk->hole_length, sizeof(uint16));
                     else
                         blk->hole_length = 0;
                 }
                 else
                     blk->hole_length = BLCKSZ - blk->bimg_len;
                 datatotal += blk->bimg_len;
  
                 /*
                  * cross-check that hole_offset > 0, hole_length > 0 and
                  * bimg_len < BLCKSZ if the HAS_HOLE flag is set.
                  */
                 if ((blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
                     (blk->hole_offset == 0 ||
                      blk->hole_length == 0 ||
                      blk->bimg_len == BLCKSZ))
                 {
                     report_invalid_record(state,
                                           "BKPIMAGE_HAS_HOLE set, but hole offset %u length %u block image length %u at %X/%X",
                                           (unsigned int) blk->hole_offset,
                                           (unsigned int) blk->hole_length,
                                           (unsigned int) blk->bimg_len,
                                           LSN_FORMAT_ARGS(state->ReadRecPtr));
                     goto err;
                 }
  
                 /*
                  * cross-check that hole_offset == 0 and hole_length == 0 if
                  * the HAS_HOLE flag is not set.
                  */
                 if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
                     (blk->hole_offset != 0 || blk->hole_length != 0))
                 {
                     report_invalid_record(state,
                                           "BKPIMAGE_HAS_HOLE not set, but hole offset %u length %u at %X/%X",
                                           (unsigned int) blk->hole_offset,
                                           (unsigned int) blk->hole_length,
                                           LSN_FORMAT_ARGS(state->ReadRecPtr));
                     goto err;
                 }
  
                 /*
                  * Cross-check that bimg_len < BLCKSZ if it is compressed.
                  */
                 if (BKPIMAGE_COMPRESSED(blk->bimg_info) &&
                     blk->bimg_len == BLCKSZ)
                 {
                     report_invalid_record(state,
                                           "BKPIMAGE_COMPRESSED set, but block image length %u at %X/%X",
                                           (unsigned int) blk->bimg_len,
                                           LSN_FORMAT_ARGS(state->ReadRecPtr));
                     goto err;
                 }
  
                 /*
                  * cross-check that bimg_len = BLCKSZ if neither HAS_HOLE is
                  * set nor COMPRESSED().
                  */
                 if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
                     !BKPIMAGE_COMPRESSED(blk->bimg_info) &&
                     blk->bimg_len != BLCKSZ)
                 {
                     report_invalid_record(state,
                                           "neither BKPIMAGE_HAS_HOLE nor BKPIMAGE_COMPRESSED set, but block image length is %u at %X/%X",
                                           (unsigned int) blk->data_len,
                                           LSN_FORMAT_ARGS(state->ReadRecPtr));
                     goto err;
                 }
             }
             if (!(fork_flags & BKPBLOCK_SAME_REL))
             {
                 COPY_HEADER_FIELD(&blk->rnode, sizeof(RelFileNode));
                 rnode = &blk->rnode;
             }
             else
             {
                 if (rnode == NULL)
                 {
                     report_invalid_record(state,
                                           "BKPBLOCK_SAME_REL set but no previous rel at %X/%X",
                                           LSN_FORMAT_ARGS(state->ReadRecPtr));
                     goto err;
                 }
  
                 blk->rnode = *rnode;
             }
             COPY_HEADER_FIELD(&blk->blkno, sizeof(BlockNumber));
         }
         else
         {
             report_invalid_record(state,
                                   "invalid block_id %u at %X/%X",
                                   block_id, LSN_FORMAT_ARGS(state->ReadRecPtr));
             goto err;
         }
     }
  
     if (remaining != datatotal)
         goto shortdata_err;
  
     /*
      * Ok, we've parsed the fragment headers, and verified that the total
      * length of the payload in the fragments is equal to the amount of data
      * left.  Copy the data of each fragment to contiguous space after the
      * blocks array, inserting alignment padding before the data fragments so
      * they can be cast to struct pointers by REDO routines.
      */
     out = ((char *) decoded) +
         offsetof(DecodedXLogRecord, blocks) +
         sizeof(decoded->blocks[0]) * (decoded->max_block_id + 1);
  
     /* block data first */
     for (block_id = 0; block_id <= decoded->max_block_id; block_id++)
     {
         DecodedBkpBlock *blk = &decoded->blocks[block_id];
  
         if (!blk->in_use)
             continue;
  
         Assert(blk->has_image || !blk->apply_image);
  
         if (blk->has_image)
         {
             /* no need to align image */
             blk->bkp_image = out;
             memcpy(out, ptr, blk->bimg_len);
             ptr += blk->bimg_len;
             out += blk->bimg_len;
         }
         if (blk->has_data)
         {
             out = (char *) MAXALIGN(out);
             blk->data = out;
             memcpy(blk->data, ptr, blk->data_len);
             ptr += blk->data_len;
             out += blk->data_len;
         }
     }
  
     /* and finally, the main data */
     if (decoded->main_data_len > 0)
     {
         out = (char *) MAXALIGN(out);
         decoded->main_data = out;
         memcpy(decoded->main_data, ptr, decoded->main_data_len);
         ptr += decoded->main_data_len;
         out += decoded->main_data_len;
     }
  
     /* Report the actual size we used. */
     decoded->size = MAXALIGN(out - (char *) decoded);
     Assert(DecodeXLogRecordRequiredSpace(record->xl_tot_len) >=
            decoded->size);
  
     return true;
  
 shortdata_err:
     report_invalid_record(state,
                           "record with invalid length at %X/%X",
                           LSN_FORMAT_ARGS(state->ReadRecPtr));
 err:
     *errormsg = state->errormsg_buf;
  
     return false;
 }

Referenced by XLogDecodeNextRecord(), and XLogInsertRecord().

◆ DecodeXLogRecordRequiredSpace()

size_t DecodeXLogRecordRequiredSpace ( size_t xl_tot_len )

Definition at line 1586 of file xlogreader.c.

 {
     size_t      size = 0;
  
     /* Account for the fixed size part of the decoded record struct. */
     size += offsetof(DecodedXLogRecord, blocks[0]);
     /* Account for the flexible blocks array of maximum possible size. */
     size += sizeof(DecodedBkpBlock) * (XLR_MAX_BLOCK_ID + 1);
     /* Account for all the raw main and block data. */
     size += xl_tot_len;
     /* We might insert padding before main_data. */
     size += (MAXIMUM_ALIGNOF - 1);
     /* We might insert padding before each block's data. */
     size += (MAXIMUM_ALIGNOF - 1) * (XLR_MAX_BLOCK_ID + 1);
     /* We might insert padding at the end. */
     size += (MAXIMUM_ALIGNOF - 1);
  
     return size;
 }

References offsetof, and XLR_MAX_BLOCK_ID.

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

◆ ReadPageInternal()

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

static

Definition at line 972 of file xlogreader.c.

 {
     int         readLen;
     uint32      targetPageOff;
     XLogSegNo   targetSegNo;
     XLogPageHeader hdr;
  
     Assert((pageptr % XLOG_BLCKSZ) == 0);
  
     XLByteToSeg(pageptr, targetSegNo, state->segcxt.ws_segsize);
     targetPageOff = XLogSegmentOffset(pageptr, state->segcxt.ws_segsize);
  
     /* check whether we have all the requested data already */
     if (targetSegNo == state->seg.ws_segno &&
         targetPageOff == state->segoff && reqLen <= state->readLen)
         return state->readLen;
  
     /*
      * Data is not in our buffer.
      *
      * Every time we actually read the segment, even if we looked at parts of
      * it before, we need to do verification as the page_read callback might
      * now be rereading data from a different source.
      *
      * Whenever switching to a new WAL segment, we read the first page of the
      * file and validate its header, even if that's not where the target
      * record is.  This is so that we can check the additional identification
      * info that is present in the first page's "long" header.
      */
     if (targetSegNo != state->seg.ws_segno && targetPageOff != 0)
     {
         XLogRecPtr  targetSegmentPtr = pageptr - targetPageOff;
  
         readLen = state->routine.page_read(state, targetSegmentPtr, XLOG_BLCKSZ,
                                            state->currRecPtr,
                                            state->readBuf);
         if (readLen == XLREAD_WOULDBLOCK)
             return XLREAD_WOULDBLOCK;
         else if (readLen < 0)
             goto err;
  
         /* we can be sure to have enough WAL available, we scrolled back */
         Assert(readLen == XLOG_BLCKSZ);
  
         if (!XLogReaderValidatePageHeader(state, targetSegmentPtr,
                                           state->readBuf))
             goto err;
     }
  
     /*
      * First, read the requested data length, but at least a short page header
      * so that we can validate it.
      */
     readLen = state->routine.page_read(state, pageptr, Max(reqLen, SizeOfXLogShortPHD),
                                        state->currRecPtr,
                                        state->readBuf);
     if (readLen == XLREAD_WOULDBLOCK)
         return XLREAD_WOULDBLOCK;
     else if (readLen < 0)
         goto err;
  
     Assert(readLen <= XLOG_BLCKSZ);
  
     /* Do we have enough data to check the header length? */
     if (readLen <= SizeOfXLogShortPHD)
         goto err;
  
     Assert(readLen >= reqLen);
  
     hdr = (XLogPageHeader) state->readBuf;
  
     /* still not enough */
     if (readLen < XLogPageHeaderSize(hdr))
     {
         readLen = state->routine.page_read(state, pageptr, XLogPageHeaderSize(hdr),
                                            state->currRecPtr,
                                            state->readBuf);
         if (readLen == XLREAD_WOULDBLOCK)
             return XLREAD_WOULDBLOCK;
         else if (readLen < 0)
             goto err;
     }
  
     /*
      * Now that we know we have the full header, validate it.
      */
     if (!XLogReaderValidatePageHeader(state, pageptr, (char *) hdr))
         goto err;
  
     /* update read state information */
     state->seg.ws_segno = targetSegNo;
     state->segoff = targetPageOff;
     state->readLen = readLen;
  
     return readLen;
  
 err:
     if (state->errormsg_buf[0] != '\0')
     {
         state->errormsg_deferred = true;
         XLogReaderInvalReadState(state);
     }
     return XLREAD_FAIL;
 }

References Assert(), 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 73 of file xlogreader.c.

 {
     va_list     args;
  
     fmt = _(fmt);
  
     va_start(args, fmt);
     vsnprintf(state->errormsg_buf, MAX_ERRORMSG_LEN, fmt, args);
     va_end(args);
  
     state->errormsg_deferred = true;
 }

References _, generate_unaccent_rules::args, fmt, MAX_ERRORMSG_LEN, va_end(), va_start(), and vsnprintf.

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

◆ ResetDecoder()

static void ResetDecoder ( XLogReaderState * state )

static

Definition at line 1552 of file xlogreader.c.

 {
     DecodedXLogRecord *r;
  
     /* Reset the decoded record queue, freeing any oversized records. */
     while ((r = state->decode_queue_head) != NULL)
     {
         state->decode_queue_head = r->next;
         if (r->oversized)
             pfree(r);
     }
     state->decode_queue_tail = NULL;
     state->decode_queue_head = NULL;
     state->record = NULL;
  
     /* Reset the decode buffer to empty. */
     state->decode_buffer_tail = state->decode_buffer;
     state->decode_buffer_head = state->decode_buffer;
  
     /* Clear error state. */
     state->errormsg_buf[0] = '\0';
     state->errormsg_deferred = false;
 }

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

Referenced by XLogBeginRead().

◆ RestoreBlockImage()

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

Definition at line 2011 of file xlogreader.c.

 {
     DecodedBkpBlock *bkpb;
     char       *ptr;
     PGAlignedBlock tmp;
  
     if (block_id > record->record->max_block_id ||
         !record->record->blocks[block_id].in_use)
         return false;
     if (!record->record->blocks[block_id].has_image)
         return false;
  
     bkpb = &record->record->blocks[block_id];
     ptr = bkpb->bkp_image;
  
     if (BKPIMAGE_COMPRESSED(bkpb->bimg_info))
     {
         /* If a backup block image is compressed, decompress it */
         bool        decomp_success = true;
  
         if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_PGLZ) != 0)
         {
             if (pglz_decompress(ptr, bkpb->bimg_len, tmp.data,
                                 BLCKSZ - bkpb->hole_length, true) < 0)
                 decomp_success = false;
         }
         else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_LZ4) != 0)
         {
 #ifdef USE_LZ4
             if (LZ4_decompress_safe(ptr, tmp.data,
                                     bkpb->bimg_len, BLCKSZ - bkpb->hole_length) <= 0)
                 decomp_success = false;
 #else
             report_invalid_record(record, "image at %X/%X compressed with %s not supported by build, block %d",
                                   LSN_FORMAT_ARGS(record->ReadRecPtr),
                                   "LZ4",
                                   block_id);
             return false;
 #endif
         }
         else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_ZSTD) != 0)
         {
 #ifdef USE_ZSTD
             size_t      decomp_result = ZSTD_decompress(tmp.data,
                                                         BLCKSZ - bkpb->hole_length,
                                                         ptr, bkpb->bimg_len);
  
             if (ZSTD_isError(decomp_result))
                 decomp_success = false;
 #else
             report_invalid_record(record, "image at %X/%X compressed with %s not supported by build, block %d",
                                   LSN_FORMAT_ARGS(record->ReadRecPtr),
                                   "zstd",
                                   block_id);
             return false;
 #endif
         }
         else
         {
             report_invalid_record(record, "image at %X/%X compressed with unknown method, block %d",
                                   LSN_FORMAT_ARGS(record->ReadRecPtr),
                                   block_id);
             return false;
         }
  
         if (!decomp_success)
         {
             report_invalid_record(record, "invalid compressed image at %X/%X, block %d",
                                   LSN_FORMAT_ARGS(record->ReadRecPtr),
                                   block_id);
             return false;
         }
  
         ptr = tmp.data;
     }
  
     /* generate page, taking into account hole if necessary */
     if (bkpb->hole_length == 0)
     {
         memcpy(page, ptr, BLCKSZ);
     }
     else
     {
         memcpy(page, ptr, bkpb->hole_offset);
         /* must zero-fill the hole */
         MemSet(page + bkpb->hole_offset, 0, bkpb->hole_length);
         memcpy(page + (bkpb->hole_offset + bkpb->hole_length),
                ptr + bkpb->hole_offset,
                BLCKSZ - (bkpb->hole_offset + bkpb->hole_length));
     }
  
     return true;
 }

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 verifyBackupPageConsistency(), and XLogReadBufferForRedoExtended().

◆ ValidXLogRecord()

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

static

Definition at line 1161 of file xlogreader.c.

 {
     pg_crc32c   crc;
  
     /* Calculate the CRC */
     INIT_CRC32C(crc);
     COMP_CRC32C(crc, ((char *) record) + SizeOfXLogRecord, record->xl_tot_len - SizeOfXLogRecord);
     /* include the record header last */
     COMP_CRC32C(crc, (char *) record, offsetof(XLogRecord, xl_crc));
     FIN_CRC32C(crc);
  
     if (!EQ_CRC32C(record->xl_crc, crc))
     {
         report_invalid_record(state,
                               "incorrect resource manager data checksum in record at %X/%X",
                               LSN_FORMAT_ARGS(recptr));
         return false;
     }
  
     return true;
 }

References COMP_CRC32C, crc, EQ_CRC32C, FIN_CRC32C, INIT_CRC32C, LSN_FORMAT_ARGS, offsetof, 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 1095 of file xlogreader.c.

 {
     if (record->xl_tot_len < SizeOfXLogRecord)
     {
         report_invalid_record(state,
                               "invalid record length at %X/%X: wanted %u, got %u",
                               LSN_FORMAT_ARGS(RecPtr),
                               (uint32) SizeOfXLogRecord, record->xl_tot_len);
         return false;
     }
     if (!RmgrIdIsValid(record->xl_rmid))
     {
         report_invalid_record(state,
                               "invalid resource manager ID %u at %X/%X",
                               record->xl_rmid, LSN_FORMAT_ARGS(RecPtr));
         return false;
     }
     if (randAccess)
     {
         /*
          * We can't exactly verify the prev-link, but surely it should be less
          * than the record's own address.
          */
         if (!(record->xl_prev < RecPtr))
         {
             report_invalid_record(state,
                                   "record with incorrect prev-link %X/%X at %X/%X",
                                   LSN_FORMAT_ARGS(record->xl_prev),
                                   LSN_FORMAT_ARGS(RecPtr));
             return false;
         }
     }
     else
     {
         /*
          * Record's prev-link should exactly match our previous location. This
          * check guards against torn WAL pages where a stale but valid-looking
          * WAL record starts on a sector boundary.
          */
         if (record->xl_prev != PrevRecPtr)
         {
             report_invalid_record(state,
                                   "record with incorrect prev-link %X/%X at %X/%X",
                                   LSN_FORMAT_ARGS(record->xl_prev),
                                   LSN_FORMAT_ARGS(RecPtr));
             return false;
         }
     }
  
     return true;
 }

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 240 of file xlogreader.c.

 {
     seg->ws_file = -1;
     seg->ws_segno = 0;
     seg->ws_tli = 0;
  
     segcxt->ws_segsize = segsize;
     if (waldir)
         snprintf(segcxt->ws_dir, MAXPGPATH, "%s", waldir);
 }

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 1460 of file xlogreader.c.

 {
     char       *p;
     XLogRecPtr  recptr;
     Size        nbytes;
  
     p = buf;
     recptr = startptr;
     nbytes = count;
  
     while (nbytes > 0)
     {
         uint32      startoff;
         int         segbytes;
         int         readbytes;
  
         startoff = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
  
         /*
          * If the data we want is not in a segment we have open, close what we
          * have (if anything) and open the next one, using the caller's
          * provided openSegment callback.
          */
         if (state->seg.ws_file < 0 ||
             !XLByteInSeg(recptr, state->seg.ws_segno, state->segcxt.ws_segsize) ||
             tli != state->seg.ws_tli)
         {
             XLogSegNo   nextSegNo;
  
             if (state->seg.ws_file >= 0)
                 state->routine.segment_close(state);
  
             XLByteToSeg(recptr, nextSegNo, state->segcxt.ws_segsize);
             state->routine.segment_open(state, nextSegNo, &tli);
  
             /* This shouldn't happen -- indicates a bug in segment_open */
             Assert(state->seg.ws_file >= 0);
  
             /* Update the current segment info. */
             state->seg.ws_tli = tli;
             state->seg.ws_segno = nextSegNo;
         }
  
         /* How many bytes are within this segment? */
         if (nbytes > (state->segcxt.ws_segsize - startoff))
             segbytes = state->segcxt.ws_segsize - startoff;
         else
             segbytes = nbytes;
  
 #ifndef FRONTEND
         pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
 #endif
  
         /* Reset errno first; eases reporting non-errno-affecting errors */
         errno = 0;
         readbytes = pg_pread(state->seg.ws_file, p, segbytes, (off_t) startoff);
  
 #ifndef FRONTEND
         pgstat_report_wait_end();
 #endif
  
         if (readbytes <= 0)
         {
             errinfo->wre_errno = errno;
             errinfo->wre_req = segbytes;
             errinfo->wre_read = readbytes;
             errinfo->wre_off = startoff;
             errinfo->wre_seg = state->seg;
             return false;
         }
  
         /* Update state for read */
         recptr += readbytes;
         nbytes -= readbytes;
         p += readbytes;
     }
  
     return true;
 }

References Assert(), buf, pg_pread(), pgstat_report_wait_end(), pgstat_report_wait_start(), WAIT_EVENT_WAL_READ, 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(), WALDumpReadPage(), and XLogSendPhysical().

◆ XLogBeginRead()

void XLogBeginRead	(	XLogReaderState *	state,
		XLogRecPtr	RecPtr
	)

Definition at line 264 of file xlogreader.c.

 {
     Assert(!XLogRecPtrIsInvalid(RecPtr));
  
     ResetDecoder(state);
  
     /* Begin at the passed-in record pointer. */
     state->EndRecPtr = RecPtr;
     state->NextRecPtr = RecPtr;
     state->ReadRecPtr = InvalidXLogRecPtr;
     state->DecodeRecPtr = InvalidXLogRecPtr;
 }

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

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

◆ XLogDecodeNextRecord()

static XLogPageReadResult XLogDecodeNextRecord	(	XLogReaderState *	state,
		bool	non_blocking
	)

static

Definition at line 531 of file xlogreader.c.

 {
     XLogRecPtr  RecPtr;
     XLogRecord *record;
     XLogRecPtr  targetPagePtr;
     bool        randAccess;
     uint32      len,
                 total_len;
     uint32      targetRecOff;
     uint32      pageHeaderSize;
     bool        assembled;
     bool        gotheader;
     int         readOff;
     DecodedXLogRecord *decoded;
     char       *errormsg;       /* not used */
  
     /*
      * randAccess indicates whether to verify the previous-record pointer of
      * the record we're reading.  We only do this if we're reading
      * sequentially, which is what we initially assume.
      */
     randAccess = false;
  
     /* reset error state */
     state->errormsg_buf[0] = '\0';
     decoded = NULL;
  
     state->abortedRecPtr = InvalidXLogRecPtr;
     state->missingContrecPtr = InvalidXLogRecPtr;
  
     RecPtr = state->NextRecPtr;
  
     if (state->DecodeRecPtr != InvalidXLogRecPtr)
     {
         /* read the record after the one we just read */
  
         /*
          * NextRecPtr is pointing to end+1 of the previous WAL record.  If
          * we're at a page boundary, no more records can fit on the current
          * page. We must skip over the page header, but we can't do that until
          * we've read in the page, since the header size is variable.
          */
     }
     else
     {
         /*
          * Caller supplied a position to start at.
          *
          * In this case, NextRecPtr should already be pointing to a valid
          * record starting position.
          */
         Assert(XRecOffIsValid(RecPtr));
         randAccess = true;
     }
  
 restart:
     state->nonblocking = nonblocking;
     state->currRecPtr = RecPtr;
     assembled = false;
  
     targetPagePtr = RecPtr - (RecPtr % XLOG_BLCKSZ);
     targetRecOff = RecPtr % XLOG_BLCKSZ;
  
     /*
      * Read the page containing the record into state->readBuf. Request enough
      * byte to cover the whole record header, or at least the part of it that
      * fits on the same page.
      */
     readOff = ReadPageInternal(state, targetPagePtr,
                                Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ));
     if (readOff == XLREAD_WOULDBLOCK)
         return XLREAD_WOULDBLOCK;
     else if (readOff < 0)
         goto err;
  
     /*
      * ReadPageInternal always returns at least the page header, so we can
      * examine it now.
      */
     pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
     if (targetRecOff == 0)
     {
         /*
          * At page start, so skip over page header.
          */
         RecPtr += pageHeaderSize;
         targetRecOff = pageHeaderSize;
     }
     else if (targetRecOff < pageHeaderSize)
     {
         report_invalid_record(state, "invalid record offset at %X/%X",
                               LSN_FORMAT_ARGS(RecPtr));
         goto err;
     }
  
     if ((((XLogPageHeader) state->readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
         targetRecOff == pageHeaderSize)
     {
         report_invalid_record(state, "contrecord is requested by %X/%X",
                               LSN_FORMAT_ARGS(RecPtr));
         goto err;
     }
  
     /* ReadPageInternal has verified the page header */
     Assert(pageHeaderSize <= readOff);
  
     /*
      * Read the record length.
      *
      * NB: Even though we use an XLogRecord pointer here, the whole record
      * header might not fit on this page. xl_tot_len is the first field of the
      * struct, so it must be on this page (the records are MAXALIGNed), but we
      * cannot access any other fields until we've verified that we got the
      * whole header.
      */
     record = (XLogRecord *) (state->readBuf + RecPtr % XLOG_BLCKSZ);
     total_len = record->xl_tot_len;
  
     /*
      * If the whole record header is on this page, validate it immediately.
      * Otherwise do just a basic sanity check on xl_tot_len, and validate the
      * rest of the header after reading it from the next page.  The xl_tot_len
      * check is necessary here to ensure that we enter the "Need to reassemble
      * record" code path below; otherwise we might fail to apply
      * ValidXLogRecordHeader at all.
      */
     if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord)
     {
         if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr, record,
                                    randAccess))
             goto err;
         gotheader = true;
     }
     else
     {
         /* XXX: more validation should be done here */
         if (total_len < SizeOfXLogRecord)
         {
             report_invalid_record(state,
                                   "invalid record length at %X/%X: wanted %u, got %u",
                                   LSN_FORMAT_ARGS(RecPtr),
                                   (uint32) SizeOfXLogRecord, total_len);
             goto err;
         }
         gotheader = false;
     }
  
     /*
      * Find space to decode this record.  Don't allow oversized allocation if
      * the caller requested nonblocking.  Otherwise, we *have* to try to
      * decode the record now because the caller has nothing else to do, so
      * allow an oversized record to be palloc'd if that turns out to be
      * necessary.
      */
     decoded = XLogReadRecordAlloc(state,
                                   total_len,
                                   !nonblocking /* allow_oversized */ );
     if (decoded == NULL)
     {
         /*
          * There is no space in the decode buffer.  The caller should help
          * with that problem by consuming some records.
          */
         if (nonblocking)
             return XLREAD_WOULDBLOCK;
  
         /* We failed to allocate memory for an oversized record. */
         report_invalid_record(state,
                               "out of memory while trying to decode a record of length %u", total_len);
         goto err;
     }
  
     len = XLOG_BLCKSZ - RecPtr % XLOG_BLCKSZ;
     if (total_len > len)
     {
         /* Need to reassemble record */
         char       *contdata;
         XLogPageHeader pageHeader;
         char       *buffer;
         uint32      gotlen;
  
         assembled = true;
  
         /*
          * Enlarge readRecordBuf as needed.
          */
         if (total_len > state->readRecordBufSize &&
             !allocate_recordbuf(state, total_len))
         {
             /* We treat this as a "bogus data" condition */
             report_invalid_record(state, "record length %u at %X/%X too long",
                                   total_len, LSN_FORMAT_ARGS(RecPtr));
             goto err;
         }
  
         /* Copy the first fragment of the record from the first page. */
         memcpy(state->readRecordBuf,
                state->readBuf + RecPtr % XLOG_BLCKSZ, len);
         buffer = state->readRecordBuf + len;
         gotlen = len;
  
         do
         {
             /* Calculate pointer to beginning of next page */
             targetPagePtr += XLOG_BLCKSZ;
  
             /* Wait for the next page to become available */
             readOff = ReadPageInternal(state, targetPagePtr,
                                        Min(total_len - gotlen + SizeOfXLogShortPHD,
                                            XLOG_BLCKSZ));
  
             if (readOff == XLREAD_WOULDBLOCK)
                 return XLREAD_WOULDBLOCK;
             else if (readOff < 0)
                 goto err;
  
             Assert(SizeOfXLogShortPHD <= readOff);
  
             pageHeader = (XLogPageHeader) state->readBuf;
  
             /*
              * If we were expecting a continuation record and got an
              * "overwrite contrecord" flag, that means the continuation record
              * was overwritten with a different record.  Restart the read by
              * assuming the address to read is the location where we found
              * this flag; but keep track of the LSN of the record we were
              * reading, for later verification.
              */
             if (pageHeader->xlp_info & XLP_FIRST_IS_OVERWRITE_CONTRECORD)
             {
                 state->overwrittenRecPtr = RecPtr;
                 RecPtr = targetPagePtr;
                 goto restart;
             }
  
             /* Check that the continuation on next page looks valid */
             if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD))
             {
                 report_invalid_record(state,
                                       "there is no contrecord flag at %X/%X",
                                       LSN_FORMAT_ARGS(RecPtr));
                 goto err;
             }
  
             /*
              * Cross-check that xlp_rem_len agrees with how much of the record
              * we expect there to be left.
              */
             if (pageHeader->xlp_rem_len == 0 ||
                 total_len != (pageHeader->xlp_rem_len + gotlen))
             {
                 report_invalid_record(state,
                                       "invalid contrecord length %u (expected %lld) at %X/%X",
                                       pageHeader->xlp_rem_len,
                                       ((long long) total_len) - gotlen,
                                       LSN_FORMAT_ARGS(RecPtr));
                 goto err;
             }
  
             /* Append the continuation from this page to the buffer */
             pageHeaderSize = XLogPageHeaderSize(pageHeader);
  
             if (readOff < pageHeaderSize)
                 readOff = ReadPageInternal(state, targetPagePtr,
                                            pageHeaderSize);
  
             Assert(pageHeaderSize <= readOff);
  
             contdata = (char *) state->readBuf + pageHeaderSize;
             len = XLOG_BLCKSZ - pageHeaderSize;
             if (pageHeader->xlp_rem_len < len)
                 len = pageHeader->xlp_rem_len;
  
             if (readOff < pageHeaderSize + len)
                 readOff = ReadPageInternal(state, targetPagePtr,
                                            pageHeaderSize + len);
  
             memcpy(buffer, (char *) contdata, len);
             buffer += len;
             gotlen += len;
  
             /* If we just reassembled the record header, validate it. */
             if (!gotheader)
             {
                 record = (XLogRecord *) state->readRecordBuf;
                 if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr,
                                            record, randAccess))
                     goto err;
                 gotheader = true;
             }
         } while (gotlen < total_len);
  
         Assert(gotheader);
  
         record = (XLogRecord *) state->readRecordBuf;
         if (!ValidXLogRecord(state, record, RecPtr))
             goto err;
  
         pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
         state->DecodeRecPtr = RecPtr;
         state->NextRecPtr = targetPagePtr + pageHeaderSize
             + MAXALIGN(pageHeader->xlp_rem_len);
     }
     else
     {
         /* Wait for the record data to become available */
         readOff = ReadPageInternal(state, targetPagePtr,
                                    Min(targetRecOff + total_len, XLOG_BLCKSZ));
         if (readOff == XLREAD_WOULDBLOCK)
             return XLREAD_WOULDBLOCK;
         else if (readOff < 0)
             goto err;
  
         /* Record does not cross a page boundary */
         if (!ValidXLogRecord(state, record, RecPtr))
             goto err;
  
         state->NextRecPtr = RecPtr + MAXALIGN(total_len);
  
         state->DecodeRecPtr = RecPtr;
     }
  
     /*
      * Special processing if it's an XLOG SWITCH record
      */
     if (record->xl_rmid == RM_XLOG_ID &&
         (record->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH)
     {
         /* Pretend it extends to end of segment */
         state->NextRecPtr += state->segcxt.ws_segsize - 1;
         state->NextRecPtr -= XLogSegmentOffset(state->NextRecPtr, state->segcxt.ws_segsize);
     }
  
     if (DecodeXLogRecord(state, decoded, record, RecPtr, &errormsg))
     {
         /* Record the location of the next record. */
         decoded->next_lsn = state->NextRecPtr;
  
         /*
          * If it's in the decode buffer, mark the decode buffer space as
          * occupied.
          */
         if (!decoded->oversized)
         {
             /* The new decode buffer head must be MAXALIGNed. */
             Assert(decoded->size == MAXALIGN(decoded->size));
             if ((char *) decoded == state->decode_buffer)
                 state->decode_buffer_tail = state->decode_buffer + decoded->size;
             else
                 state->decode_buffer_tail += decoded->size;
         }
  
         /* Insert it into the queue of decoded records. */
         Assert(state->decode_queue_tail != decoded);
         if (state->decode_queue_tail)
             state->decode_queue_tail->next = decoded;
         state->decode_queue_tail = decoded;
         if (!state->decode_queue_head)
             state->decode_queue_head = decoded;
         return XLREAD_SUCCESS;
     }
     else
         return XLREAD_FAIL;
  
 err:
     if (assembled)
     {
         /*
          * We get here when a record that spans multiple pages needs to be
          * assembled, but something went wrong -- perhaps a contrecord piece
          * was lost.  If caller is WAL replay, it will know where the aborted
          * record was and where to direct followup WAL to be written, marking
          * the next piece with XLP_FIRST_IS_OVERWRITE_CONTRECORD, which will
          * in turn signal downstream WAL consumers that the broken WAL record
          * is to be ignored.
          */
         state->abortedRecPtr = RecPtr;
         state->missingContrecPtr = targetPagePtr;
     }
  
     if (decoded && decoded->oversized)
         pfree(decoded);
  
     /*
      * Invalidate the read state. We might read from a different source after
      * failure.
      */
     XLogReaderInvalReadState(state);
  
     /*
      * If an error was written to errmsg_buf, it'll be returned to the caller
      * of XLogReadRecord() after all successfully decoded records from the
      * read queue.
      */
  
     return XLREAD_FAIL;
 }

References allocate_recordbuf(), Assert(), DecodeXLogRecord(), if(), InvalidXLogRecPtr, len, 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 1337 of file xlogreader.c.

 {
     XLogRecPtr  tmpRecPtr;
     XLogRecPtr  found = InvalidXLogRecPtr;
     XLogPageHeader header;
     char       *errormsg;
  
     Assert(!XLogRecPtrIsInvalid(RecPtr));
  
     /* Make sure ReadPageInternal() can't return XLREAD_WOULDBLOCK. */
     state->nonblocking = false;
  
     /*
      * skip over potential continuation data, keeping in mind that it may span
      * multiple pages
      */
     tmpRecPtr = RecPtr;
     while (true)
     {
         XLogRecPtr  targetPagePtr;
         int         targetRecOff;
         uint32      pageHeaderSize;
         int         readLen;
  
         /*
          * Compute targetRecOff. It should typically be equal or greater than
          * short page-header since a valid record can't start anywhere before
          * that, except when caller has explicitly specified the offset that
          * falls somewhere there or when we are skipping multi-page
          * continuation record. It doesn't matter though because
          * ReadPageInternal() is prepared to handle that and will read at
          * least short page-header worth of data
          */
         targetRecOff = tmpRecPtr % XLOG_BLCKSZ;
  
         /* scroll back to page boundary */
         targetPagePtr = tmpRecPtr - targetRecOff;
  
         /* Read the page containing the record */
         readLen = ReadPageInternal(state, targetPagePtr, targetRecOff);
         if (readLen < 0)
             goto err;
  
         header = (XLogPageHeader) state->readBuf;
  
         pageHeaderSize = XLogPageHeaderSize(header);
  
         /* make sure we have enough data for the page header */
         readLen = ReadPageInternal(state, targetPagePtr, pageHeaderSize);
         if (readLen < 0)
             goto err;
  
         /* skip over potential continuation data */
         if (header->xlp_info & XLP_FIRST_IS_CONTRECORD)
         {
             /*
              * If the length of the remaining continuation data is more than
              * what can fit in this page, the continuation record crosses over
              * this page. Read the next page and try again. xlp_rem_len in the
              * next page header will contain the remaining length of the
              * continuation data
              *
              * Note that record headers are MAXALIGN'ed
              */
             if (MAXALIGN(header->xlp_rem_len) >= (XLOG_BLCKSZ - pageHeaderSize))
                 tmpRecPtr = targetPagePtr + XLOG_BLCKSZ;
             else
             {
                 /*
                  * The previous continuation record ends in this page. Set
                  * tmpRecPtr to point to the first valid record
                  */
                 tmpRecPtr = targetPagePtr + pageHeaderSize
                     + MAXALIGN(header->xlp_rem_len);
                 break;
             }
         }
         else
         {
             tmpRecPtr = targetPagePtr + pageHeaderSize;
             break;
         }
     }
  
     /*
      * we know now that tmpRecPtr is an address pointing to a valid XLogRecord
      * because either we're at the first record after the beginning of a page
      * or we just jumped over the remaining data of a continuation.
      */
     XLogBeginRead(state, tmpRecPtr);
     while (XLogReadRecord(state, &errormsg) != NULL)
     {
         /* past the record we've found, break out */
         if (RecPtr <= state->ReadRecPtr)
         {
             /* Rewind the reader to the beginning of the last record. */
             found = state->ReadRecPtr;
             XLogBeginRead(state, found);
             return found;
         }
     }
  
 err:
     XLogReaderInvalReadState(state);
  
     return InvalidXLogRecPtr;
 }

References Assert(), header(), InvalidXLogRecPtr, MAXALIGN, readLen, ReadPageInternal(), XLogBeginRead(), XLogPageHeaderSize, XLogReaderInvalReadState(), XLogReadRecord(), XLogRecPtrIsInvalid, and XLP_FIRST_IS_CONTRECORD.

Referenced by InitXLogReaderState(), and main().

◆ XLogNextRecord()

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

Definition at line 354 of file xlogreader.c.

 {
     /* Release the last record returned by XLogNextRecord(). */
     XLogReleasePreviousRecord(state);
  
     if (state->decode_queue_head == NULL)
     {
         *errormsg = NULL;
         if (state->errormsg_deferred)
         {
             if (state->errormsg_buf[0] != '\0')
                 *errormsg = state->errormsg_buf;
             state->errormsg_deferred = false;
         }
  
         /*
          * state->EndRecPtr is expected to have been set by the last call to
          * XLogBeginRead() or XLogNextRecord(), and is the location of the
          * error.
          */
         Assert(!XLogRecPtrIsInvalid(state->EndRecPtr));
  
         return NULL;
     }
  
     /*
      * Record this as the most recent record returned, so that we'll release
      * it next time.  This also exposes it to the traditional
      * XLogRecXXX(xlogreader) macros, which work with the decoder rather than
      * the record for historical reasons.
      */
     state->record = state->decode_queue_head;
  
     /*
      * Update the pointers to the beginning and one-past-the-end of this
      * record, again for the benefit of historical code that expected the
      * decoder to track this rather than accessing these fields of the record
      * itself.
      */
     state->ReadRecPtr = state->record->lsn;
     state->EndRecPtr = state->record->next_lsn;
  
     *errormsg = NULL;
  
     return state->record;
 }

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

Referenced by XLogPrefetcherReadRecord(), and XLogReadRecord().

◆ XLogReadAhead()

DecodedXLogRecord* XLogReadAhead	(	XLogReaderState *	state,
		bool	nonblocking
	)

Definition at line 938 of file xlogreader.c.

 {
     XLogPageReadResult result;
  
     if (state->errormsg_deferred)
         return NULL;
  
     result = XLogDecodeNextRecord(state, nonblocking);
     if (result == XLREAD_SUCCESS)
     {
         Assert(state->decode_queue_tail != NULL);
         return state->decode_queue_tail;
     }
  
     return NULL;
 }

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 108 of file xlogreader.c.

 {
     XLogReaderState *state;
  
     state = (XLogReaderState *)
         palloc_extended(sizeof(XLogReaderState),
                         MCXT_ALLOC_NO_OOM | MCXT_ALLOC_ZERO);
     if (!state)
         return NULL;
  
     /* initialize caller-provided support functions */
     state->routine = *routine;
  
     /*
      * Permanently allocate readBuf.  We do it this way, rather than just
      * making a static array, for two reasons: (1) no need to waste the
      * storage in most instantiations of the backend; (2) a static char array
      * isn't guaranteed to have any particular alignment, whereas
      * palloc_extended() will provide MAXALIGN'd storage.
      */
     state->readBuf = (char *) palloc_extended(XLOG_BLCKSZ,
                                               MCXT_ALLOC_NO_OOM);
     if (!state->readBuf)
     {
         pfree(state);
         return NULL;
     }
  
     /* Initialize segment info. */
     WALOpenSegmentInit(&state->seg, &state->segcxt, wal_segment_size,
                        waldir);
  
     /* system_identifier initialized to zeroes above */
     state->private_data = private_data;
     /* ReadRecPtr, EndRecPtr and readLen initialized to zeroes above */
     state->errormsg_buf = palloc_extended(MAX_ERRORMSG_LEN + 1,
                                           MCXT_ALLOC_NO_OOM);
     if (!state->errormsg_buf)
     {
         pfree(state->readBuf);
         pfree(state);
         return NULL;
     }
     state->errormsg_buf[0] = '\0';
  
     /*
      * Allocate an initial readRecordBuf of minimal size, which can later be
      * enlarged if necessary.
      */
     if (!allocate_recordbuf(state, 0))
     {
         pfree(state->errormsg_buf);
         pfree(state->readBuf);
         pfree(state);
         return NULL;
     }
  
     return state;
 }

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(), XLogInsertRecord(), and XlogReadTwoPhaseData().

◆ XLogReaderFree()

void XLogReaderFree ( XLogReaderState * state )

Definition at line 170 of file xlogreader.c.

 {
     if (state->seg.ws_file != -1)
         state->routine.segment_close(state);
  
     if (state->decode_buffer && state->free_decode_buffer)
         pfree(state->decode_buffer);
  
     pfree(state->errormsg_buf);
     if (state->readRecordBuf)
         pfree(state->readRecordBuf);
     pfree(state->readBuf);
     pfree(state);
 }

References pfree().

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

◆ XLogReaderInvalReadState()

static void XLogReaderInvalReadState ( XLogReaderState * state )

static

Definition at line 1081 of file xlogreader.c.

 {
     state->seg.ws_segno = 0;
     state->segoff = 0;
     state->readLen = 0;
 }

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

◆ XLogReaderSetDecodeBuffer()

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

Definition at line 92 of file xlogreader.c.

 {
     Assert(state->decode_buffer == NULL);
  
     state->decode_buffer = buffer;
     state->decode_buffer_size = size;
     state->decode_buffer_tail = buffer;
     state->decode_buffer_head = buffer;
 }

References Assert().

Referenced by InitWalRecovery().

◆ XLogReaderValidatePageHeader()

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

Definition at line 1190 of file xlogreader.c.

 {
     XLogRecPtr  recaddr;
     XLogSegNo   segno;
     int32       offset;
     XLogPageHeader hdr = (XLogPageHeader) phdr;
  
     Assert((recptr % XLOG_BLCKSZ) == 0);
  
     XLByteToSeg(recptr, segno, state->segcxt.ws_segsize);
     offset = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
  
     XLogSegNoOffsetToRecPtr(segno, offset, state->segcxt.ws_segsize, recaddr);
  
     if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
     {
         char        fname[MAXFNAMELEN];
  
         XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
  
         report_invalid_record(state,
                               "invalid magic number %04X in log segment %s, offset %u",
                               hdr->xlp_magic,
                               fname,
                               offset);
         return false;
     }
  
     if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0)
     {
         char        fname[MAXFNAMELEN];
  
         XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
  
         report_invalid_record(state,
                               "invalid info bits %04X in log segment %s, offset %u",
                               hdr->xlp_info,
                               fname,
                               offset);
         return false;
     }
  
     if (hdr->xlp_info & XLP_LONG_HEADER)
     {
         XLogLongPageHeader longhdr = (XLogLongPageHeader) hdr;
  
         if (state->system_identifier &&
             longhdr->xlp_sysid != state->system_identifier)
         {
             report_invalid_record(state,
                                   "WAL file is from different database system: WAL file database system identifier is %llu, pg_control database system identifier is %llu",
                                   (unsigned long long) longhdr->xlp_sysid,
                                   (unsigned long long) state->system_identifier);
             return false;
         }
         else if (longhdr->xlp_seg_size != state->segcxt.ws_segsize)
         {
             report_invalid_record(state,
                                   "WAL file is from different database system: incorrect segment size in page header");
             return false;
         }
         else if (longhdr->xlp_xlog_blcksz != XLOG_BLCKSZ)
         {
             report_invalid_record(state,
                                   "WAL file is from different database system: incorrect XLOG_BLCKSZ in page header");
             return false;
         }
     }
     else if (offset == 0)
     {
         char        fname[MAXFNAMELEN];
  
         XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
  
         /* hmm, first page of file doesn't have a long header? */
         report_invalid_record(state,
                               "invalid info bits %04X in log segment %s, offset %u",
                               hdr->xlp_info,
                               fname,
                               offset);
         return false;
     }
  
     /*
      * Check that the address on the page agrees with what we expected. This
      * check typically fails when an old WAL segment is recycled, and hasn't
      * yet been overwritten with new data yet.
      */
     if (hdr->xlp_pageaddr != recaddr)
     {
         char        fname[MAXFNAMELEN];
  
         XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
  
         report_invalid_record(state,
                               "unexpected pageaddr %X/%X in log segment %s, offset %u",
                               LSN_FORMAT_ARGS(hdr->xlp_pageaddr),
                               fname,
                               offset);
         return false;
     }
  
     /*
      * Since child timelines are always assigned a TLI greater than their
      * immediate parent's TLI, we should never see TLI go backwards across
      * successive pages of a consistent WAL sequence.
      *
      * Sometimes we re-read a segment that's already been (partially) read. So
      * we only verify TLIs for pages that are later than the last remembered
      * LSN.
      */
     if (recptr > state->latestPagePtr)
     {
         if (hdr->xlp_tli < state->latestPageTLI)
         {
             char        fname[MAXFNAMELEN];
  
             XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
  
             report_invalid_record(state,
                                   "out-of-sequence timeline ID %u (after %u) in log segment %s, offset %u",
                                   hdr->xlp_tli,
                                   state->latestPageTLI,
                                   fname,
                                   offset);
             return false;
         }
     }
     state->latestPagePtr = recptr;
     state->latestPageTLI = hdr->xlp_tli;
  
     return true;
 }

References Assert(), LSN_FORMAT_ARGS, MAXFNAMELEN, report_invalid_record(), XLByteToSeg, XLOG_PAGE_MAGIC, XLogFileName, XLogSegmentOffset, XLogSegNoOffsetToRecPtr, 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 418 of file xlogreader.c.

 {
     DecodedXLogRecord *decoded;
  
     /*
      * Release last returned record, if there is one.  We need to do this so
      * that we can check for empty decode queue accurately.
      */
     XLogReleasePreviousRecord(state);
  
     /*
      * Call XLogReadAhead() in blocking mode to make sure there is something
      * in the queue, though we don't use the result.
      */
     if (!XLogReaderHasQueuedRecordOrError(state))
         XLogReadAhead(state, false /* nonblocking */ );
  
     /* Consume the head record or error. */
     decoded = XLogNextRecord(state, errormsg);
     if (decoded)
     {
         /*
          * This function returns a pointer to the record's header, not the
          * actual decoded record.  The caller will access the decoded record
          * through the XLogRecGetXXX() macros, which reach the decoded
          * recorded as xlogreader->record.
          */
         Assert(state->record == decoded);
         return &decoded->header;
     }
  
     return NULL;
 }

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

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

◆ XLogReadRecordAlloc()

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

static

Definition at line 467 of file xlogreader.c.

 {
     size_t      required_space = DecodeXLogRecordRequiredSpace(xl_tot_len);
     DecodedXLogRecord *decoded = NULL;
  
     /* Allocate a circular decode buffer if we don't have one already. */
     if (unlikely(state->decode_buffer == NULL))
     {
         if (state->decode_buffer_size == 0)
             state->decode_buffer_size = DEFAULT_DECODE_BUFFER_SIZE;
         state->decode_buffer = palloc(state->decode_buffer_size);
         state->decode_buffer_head = state->decode_buffer;
         state->decode_buffer_tail = state->decode_buffer;
         state->free_decode_buffer = true;
     }
  
     /* Try to allocate space in the circular decode buffer. */
     if (state->decode_buffer_tail >= state->decode_buffer_head)
     {
         /* Empty, or tail is to the right of head. */
         if (state->decode_buffer_tail + required_space <=
             state->decode_buffer + state->decode_buffer_size)
         {
             /* There is space between tail and end. */
             decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
             decoded->oversized = false;
             return decoded;
         }
         else if (state->decode_buffer + required_space <
                  state->decode_buffer_head)
         {
             /* There is space between start and head. */
             decoded = (DecodedXLogRecord *) state->decode_buffer;
             decoded->oversized = false;
             return decoded;
         }
     }
     else
     {
         /* Tail is to the left of head. */
         if (state->decode_buffer_tail + required_space <
             state->decode_buffer_head)
         {
             /* There is space between tail and head. */
             decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
             decoded->oversized = false;
             return decoded;
         }
     }
  
     /* Not enough space in the decode buffer.  Are we allowed to allocate? */
     if (allow_oversized)
     {
         decoded = palloc_extended(required_space, MCXT_ALLOC_NO_OOM);
         if (decoded == NULL)
             return NULL;
         decoded->oversized = true;
         return decoded;
     }
  
     return NULL;
 }

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

Referenced by XLogDecodeNextRecord().

◆ XLogRecGetBlockData()

char* XLogRecGetBlockData	(	XLogReaderState *	record,
		uint8	block_id,
		Size *	len
	)

Definition at line 1981 of file xlogreader.c.

 {
     DecodedBkpBlock *bkpb;
  
     if (block_id > record->record->max_block_id ||
         !record->record->blocks[block_id].in_use)
         return NULL;
  
     bkpb = &record->record->blocks[block_id];
  
     if (!bkpb->has_data)
     {
         if (len)
             *len = 0;
         return NULL;
     }
     else
     {
         if (len)
             *len = bkpb->data_len;
         return bkpb->data;
     }
 }

References DecodedXLogRecord::blocks, DecodedBkpBlock::data, DecodedBkpBlock::data_len, DecodedBkpBlock::has_data, DecodedBkpBlock::in_use, len, DecodedXLogRecord::max_block_id, and XLogReaderState::record.

Referenced by _bt_restore_meta(), brin_xlog_insert_update(), brin_xlog_samepage_update(), btree_desc(), btree_xlog_dedup(), btree_xlog_delete(), btree_xlog_insert(), btree_xlog_newroot(), btree_xlog_split(), btree_xlog_vacuum(), DecodeInsert(), DecodeMultiInsert(), DecodeUpdate(), generic_redo(), gin_desc(), ginRedoInsert(), ginRedoInsertListPage(), ginRedoUpdateMetapage(), ginRedoVacuumDataLeafPage(), gistRedoPageSplitRecord(), gistRedoPageUpdateRecord(), hash_xlog_add_ovfl_page(), hash_xlog_delete(), hash_xlog_insert(), hash_xlog_move_page_contents(), hash_xlog_split_allocate_page(), hash_xlog_squeeze_page(), heap_xlog_freeze_page(), heap_xlog_inplace(), heap_xlog_insert(), heap_xlog_multi_insert(), heap_xlog_prune(), heap_xlog_update(), and heap_xlog_vacuum().

◆ XLogRecGetBlockTag()

void XLogRecGetBlockTag	(	XLogReaderState *	record,
		uint8	block_id,
		RelFileNode *	rnode,
		ForkNumber *	forknum,
		BlockNumber *	blknum
	)

Definition at line 1928 of file xlogreader.c.

 {
     if (!XLogRecGetBlockTagExtended(record, block_id, rnode, forknum, blknum,
                                     NULL))
     {
 #ifndef FRONTEND
         elog(ERROR, "failed to locate backup block with ID %d in WAL record",
              block_id);
 #else
         pg_fatal("failed to locate backup block with ID %d in WAL record",
                  block_id);
 #endif
     }
 }

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_freeze_page(), heap_xlog_insert(), heap_xlog_lock(), heap_xlog_lock_updated(), heap_xlog_multi_insert(), heap_xlog_prune(), heap_xlog_update(), heap_xlog_vacuum(), heap_xlog_visible(), spgRedoAddLeaf(), spgRedoAddNode(), spgRedoMoveLeafs(), spgRedoPickSplit(), and spgRedoVacuumRedirect().

◆ XLogRecGetBlockTagExtended()

bool XLogRecGetBlockTagExtended	(	XLogReaderState *	record,
		uint8	block_id,
		RelFileNode *	rnode,
		ForkNumber *	forknum,
		BlockNumber *	blknum,
		Buffer *	prefetch_buffer
	)

Definition at line 1953 of file xlogreader.c.

 {
     DecodedBkpBlock *bkpb;
  
     if (!XLogRecHasBlockRef(record, block_id))
         return false;
  
     bkpb = &record->record->blocks[block_id];
     if (rnode)
         *rnode = bkpb->rnode;
     if (forknum)
         *forknum = bkpb->forknum;
     if (blknum)
         *blknum = bkpb->blkno;
     if (prefetch_buffer)
         *prefetch_buffer = bkpb->prefetch_buffer;
     return true;
 }

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

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

◆ XLogRecGetFullXid()

FullTransactionId XLogRecGetFullXid ( XLogReaderState * record )

Definition at line 2111 of file xlogreader.c.

 {
     TransactionId xid,
                 next_xid;
     uint32      epoch;
  
     /*
      * This function is only safe during replay, because it depends on the
      * replay state.  See AdvanceNextFullTransactionIdPastXid() for more.
      */
     Assert(AmStartupProcess() || !IsUnderPostmaster);
  
     xid = XLogRecGetXid(record);
     next_xid = XidFromFullTransactionId(ShmemVariableCache->nextXid);
     epoch = EpochFromFullTransactionId(ShmemVariableCache->nextXid);
  
     /*
      * If xid is numerically greater than next_xid, it has to be from the last
      * epoch.
      */
     if (unlikely(xid > next_xid))
         --epoch;
  
     return FullTransactionIdFromEpochAndXid(epoch, xid);
 }

References AmStartupProcess, Assert(), epoch, EpochFromFullTransactionId, FullTransactionIdFromEpochAndXid(), IsUnderPostmaster, VariableCacheData::nextXid, ShmemVariableCache, unlikely, XidFromFullTransactionId, and XLogRecGetXid.

◆ XLogReleasePreviousRecord()

void XLogReleasePreviousRecord ( XLogReaderState * state )

Definition at line 282 of file xlogreader.c.

 {
     DecodedXLogRecord *record;
  
     if (!state->record)
         return;
  
     /*
      * Remove it from the decoded record queue.  It must be the oldest item
      * decoded, decode_queue_head.
      */
     record = state->record;
     Assert(record == state->decode_queue_head);
     state->record = NULL;
     state->decode_queue_head = record->next;
  
     /* It might also be the newest item decoded, decode_queue_tail. */
     if (state->decode_queue_tail == record)
         state->decode_queue_tail = NULL;
  
     /* Release the space. */
     if (unlikely(record->oversized))
     {
         /* It's not in the decode buffer, so free it to release space. */
         pfree(record);
     }
     else
     {
         /* It must be the head (oldest) record in the decode buffer. */
         Assert(state->decode_buffer_head == (char *) record);
  
         /*
          * We need to update head to point to the next record that is in the
          * decode buffer, if any, being careful to skip oversized ones
          * (they're not in the decode buffer).
          */
         record = record->next;
         while (unlikely(record && record->oversized))
             record = record->next;
  
         if (record)
         {
             /* Adjust head to release space up to the next record. */
             state->decode_buffer_head = (char *) record;
         }
         else
         {
             /*
              * Otherwise we might as well just reset head and tail to the
              * start of the buffer space, because we're empty.  This means
              * we'll keep overwriting the same piece of memory if we're not
              * doing any prefetching.
              */
             state->decode_buffer_head = state->decode_buffer;
             state->decode_buffer_tail = state->decode_buffer;
         }
     }
 }

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

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

Macros

Functions

Macro Definition Documentation

◆ COPY_HEADER_FIELD

◆ DEFAULT_DECODE_BUFFER_SIZE

◆ MAX_ERRORMSG_LEN

Function Documentation

◆ allocate_recordbuf()

◆ DecodeXLogRecord()

◆ DecodeXLogRecordRequiredSpace()

◆ ReadPageInternal()

◆ report_invalid_record()

◆ ResetDecoder()

◆ RestoreBlockImage()

◆ ValidXLogRecord()

◆ ValidXLogRecordHeader()

◆ WALOpenSegmentInit()

◆ WALRead()

◆ XLogBeginRead()

◆ XLogDecodeNextRecord()

◆ XLogFindNextRecord()

◆ XLogNextRecord()

◆ XLogReadAhead()

◆ XLogReaderAllocate()

◆ XLogReaderFree()

◆ XLogReaderInvalReadState()

◆ XLogReaderSetDecodeBuffer()

◆ XLogReaderValidatePageHeader()

◆ XLogReadRecord()

◆ XLogReadRecordAlloc()

◆ XLogRecGetBlockData()

◆ XLogRecGetBlockTag()

◆ XLogRecGetBlockTagExtended()

◆ XLogRecGetFullXid()

◆ XLogReleasePreviousRecord()