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-rw-r--r--src/backend/access/transam/xlog.c118
1 files changed, 67 insertions, 51 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index c1609356d39..aa37244162a 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.196 2005/06/06 17:01:23 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.197 2005/06/06 20:22:57 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -434,7 +434,8 @@ static void exitArchiveRecovery(TimeLineID endTLI,
uint32 endLogId, uint32 endLogSeg);
static bool recoveryStopsHere(XLogRecord *record, bool *includeThis);
-static void SetBkpBlock(BkpBlock *bkpb, Buffer buffer);
+static bool XLogCheckBuffer(XLogRecData *rdata,
+ XLogRecPtr *lsn, BkpBlock *bkpb);
static bool AdvanceXLInsertBuffer(void);
static void XLogWrite(XLogwrtRqst WriteRqst);
static int XLogFileInit(uint32 log, uint32 seg,
@@ -473,7 +474,7 @@ static void remove_backup_label(void);
/*
* Insert an XLOG record having the specified RMID and info bytes,
* with the body of the record being the data chunk(s) described by
- * the rdata list (see xlog.h for notes about rdata).
+ * the rdata chain (see xlog.h for notes about rdata).
*
* Returns XLOG pointer to end of record (beginning of next record).
* This can be used as LSN for data pages affected by the logged action.
@@ -532,7 +533,7 @@ XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata)
}
/*
- * Here we scan the rdata list, determine which buffers must be backed
+ * Here we scan the rdata chain, determine which buffers must be backed
* up, and compute the CRC values for the data. Note that the record
* header isn't added into the CRC initially since we don't know the
* final length or info bits quite yet. Thus, the CRC will represent
@@ -543,13 +544,13 @@ XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata)
* below. We could prevent the race by doing all this work while
* holding the insert lock, but it seems better to avoid doing CRC
* calculations while holding the lock. This means we have to be
- * careful about modifying the rdata list until we know we aren't
+ * careful about modifying the rdata chain until we know we aren't
* going to loop back again. The only change we allow ourselves to
- * make earlier is to set rdt->data = NULL in list items we have
+ * make earlier is to set rdt->data = NULL in chain items we have
* decided we will have to back up the whole buffer for. This is OK
* because we will certainly decide the same thing again for those
* items if we do it over; doing it here saves an extra pass over the
- * list later.
+ * chain later.
*/
begin:;
for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
@@ -575,7 +576,7 @@ begin:;
{
if (rdt->buffer == dtbuf[i])
{
- /* Buffer already referenced by earlier list item */
+ /* Buffer already referenced by earlier chain item */
if (dtbuf_bkp[i])
rdt->data = NULL;
else if (rdt->data)
@@ -589,15 +590,9 @@ begin:;
{
/* OK, put it in this slot */
dtbuf[i] = rdt->buffer;
-
- /*
- * XXX We assume page LSN is first data on page
- */
- dtbuf_lsn[i] = *((XLogRecPtr *) BufferGetBlock(rdt->buffer));
- if (XLByteLE(dtbuf_lsn[i], RedoRecPtr))
+ if (XLogCheckBuffer(rdt, &(dtbuf_lsn[i]), &(dtbuf_xlg[i])))
{
dtbuf_bkp[i] = true;
- SetBkpBlock(&(dtbuf_xlg[i]), rdt->buffer);
rdt->data = NULL;
}
else if (rdt->data)
@@ -612,7 +607,7 @@ begin:;
elog(PANIC, "can backup at most %d blocks per xlog record",
XLR_MAX_BKP_BLOCKS);
}
- /* Break out of loop when rdt points to last list item */
+ /* Break out of loop when rdt points to last chain item */
if (rdt->next == NULL)
break;
rdt = rdt->next;
@@ -726,15 +721,15 @@ begin:;
}
/*
- * Make additional rdata list entries for the backup blocks, so that
+ * Make additional rdata chain entries for the backup blocks, so that
* we don't need to special-case them in the write loop. Note that we
- * have now irrevocably changed the input rdata list. At the exit of
+ * have now irrevocably changed the input rdata chain. At the exit of
* this loop, write_len includes the backup block data.
*
* Also set the appropriate info bits to show which buffers were backed
* up. The i'th XLR_SET_BKP_BLOCK bit corresponds to the i'th
* distinct buffer value (ignoring InvalidBuffer) appearing in the
- * rdata list.
+ * rdata chain.
*/
write_len = len;
for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
@@ -742,7 +737,7 @@ begin:;
BkpBlock *bkpb;
char *page;
- if (dtbuf[i] == InvalidBuffer || !(dtbuf_bkp[i]))
+ if (!dtbuf_bkp[i])
continue;
info |= XLR_SET_BKP_BLOCK(i);
@@ -938,43 +933,64 @@ begin:;
}
/*
- * Fill a BkpBlock struct given a buffer containing the page to be saved
- *
- * This is nontrivial only because it has to decide whether to apply "hole
- * compression".
+ * Determine whether the buffer referenced by an XLogRecData item has to
+ * be backed up, and if so fill a BkpBlock struct for it. In any case
+ * save the buffer's LSN at *lsn.
*/
-static void
-SetBkpBlock(BkpBlock *bkpb, Buffer buffer)
+static bool
+XLogCheckBuffer(XLogRecData *rdata,
+ XLogRecPtr *lsn, BkpBlock *bkpb)
{
PageHeader page;
- uint16 offset;
- uint16 length;
- /* Save page identity info */
- bkpb->node = BufferGetFileNode(buffer);
- bkpb->block = BufferGetBlockNumber(buffer);
+ page = (PageHeader) BufferGetBlock(rdata->buffer);
+
+ /*
+ * XXX We assume page LSN is first data on *every* page that can be
+ * passed to XLogInsert, whether it otherwise has the standard page
+ * layout or not.
+ */
+ *lsn = page->pd_lsn;
- /* Test whether there is a "hole" containing zeroes in the page */
- page = (PageHeader) BufferGetBlock(buffer);
- offset = page->pd_lower;
- /* Check if pd_lower appears sane at all */
- if (offset >= SizeOfPageHeaderData && offset < BLCKSZ)
+ if (XLByteLE(page->pd_lsn, RedoRecPtr))
{
- char *spd = (char *) page + offset;
- char *epd = (char *) page + BLCKSZ;
- char *pd = spd;
+ /*
+ * The page needs to be backed up, so set up *bkpb
+ */
+ bkpb->node = BufferGetFileNode(rdata->buffer);
+ bkpb->block = BufferGetBlockNumber(rdata->buffer);
+
+ if (rdata->buffer_std)
+ {
+ /* Assume we can omit data between pd_lower and pd_upper */
+ uint16 lower = page->pd_lower;
+ uint16 upper = page->pd_upper;
- while (pd < epd && *pd == '\0')
- pd++;
+ if (lower >= SizeOfPageHeaderData &&
+ upper > lower &&
+ upper <= BLCKSZ)
+ {
+ bkpb->hole_offset = lower;
+ bkpb->hole_length = upper - lower;
+ }
+ else
+ {
+ /* No "hole" to compress out */
+ bkpb->hole_offset = 0;
+ bkpb->hole_length = 0;
+ }
+ }
+ else
+ {
+ /* Not a standard page header, don't try to eliminate "hole" */
+ bkpb->hole_offset = 0;
+ bkpb->hole_length = 0;
+ }
- length = pd - spd;
- if (length == 0)
- offset = 0;
+ return true; /* buffer requires backup */
}
- else
- offset = length = 0;
- bkpb->hole_offset = offset;
- bkpb->hole_length = length;
+
+ return false; /* buffer does not need to be backed up */
}
/*
@@ -5093,9 +5109,9 @@ CreateCheckPoint(bool shutdown, bool force)
/*
* Now insert the checkpoint record into XLOG.
*/
- rdata.buffer = InvalidBuffer;
rdata.data = (char *) (&checkPoint);
rdata.len = sizeof(checkPoint);
+ rdata.buffer = InvalidBuffer;
rdata.next = NULL;
recptr = XLogInsert(RM_XLOG_ID,
@@ -5197,9 +5213,9 @@ XLogPutNextOid(Oid nextOid)
{
XLogRecData rdata;
- rdata.buffer = InvalidBuffer;
rdata.data = (char *) (&nextOid);
rdata.len = sizeof(Oid);
+ rdata.buffer = InvalidBuffer;
rdata.next = NULL;
(void) XLogInsert(RM_XLOG_ID, XLOG_NEXTOID, &rdata);
/*
@@ -5220,9 +5236,9 @@ XLogPutNextMultiXactId(MultiXactId nextMulti)
{
XLogRecData rdata;
- rdata.buffer = InvalidBuffer;
rdata.data = (char *) (&nextMulti);
rdata.len = sizeof(MultiXactId);
+ rdata.buffer = InvalidBuffer;
rdata.next = NULL;
(void) XLogInsert(RM_XLOG_ID, XLOG_NEXTMULTI, &rdata);
/*
generated by cgit v1.2.3 (git 2.25.1) at 2025-06-29 14:47:24 +0000