diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index c9e3a7af7b3b35b95d017f06e749739c715a8524..8d43660353f5f98d6b171b5f3b3895d37969f4a6 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -457,15 +457,6 @@ typedef struct XLogCtlInsert
XLogRecPtr lastBackupStart;
} XLogCtlInsert;
-/*
- * Shared state data for XLogWrite/XLogFlush.
- */
-typedef struct XLogCtlWrite
-{
- int curridx; /* cache index of next block to write */
- pg_time_t lastSegSwitchTime; /* time of last xlog segment switch */
-} XLogCtlWrite;
-
/*
* Total shared-memory state for XLOG.
*/
@@ -482,12 +473,12 @@ typedef struct XLogCtlData
XLogSegNo lastRemovedSegNo; /* latest removed/recycled XLOG
* segment */
- /* Fake LSN counter, for unlogged relations. Protected by ulsn_lck */
+ /* Fake LSN counter, for unlogged relations. Protected by ulsn_lck. */
XLogRecPtr unloggedLSN;
slock_t ulsn_lck;
- /* Protected by WALWriteLock: */
- XLogCtlWrite Write;
+ /* Time of last xlog segment switch. Protected by WALWriteLock. */
+ pg_time_t lastSegSwitchTime;
/*
* Protected by info_lck and WALWriteLock (you must hold either lock to
@@ -496,15 +487,15 @@ typedef struct XLogCtlData
XLogwrtResult LogwrtResult;
/*
- * Latest initialized block index in cache.
+ * Latest initialized page in the cache (last byte position + 1).
*
- * To change curridx and the identity of a buffer, you need to hold
- * WALBufMappingLock. To change the identity of a buffer that's still
+ * To change the identity of a buffer (and InitializedUpTo), you need to
+ * hold WALBufMappingLock. To change the identity of a buffer that's still
* dirty, the old page needs to be written out first, and for that you
* need WALWriteLock, and you need to ensure that there are no in-progress
* insertions to the page by calling WaitXLogInsertionsToFinish().
*/
- int curridx;
+ XLogRecPtr InitializedUpTo;
/*
* These values do not change after startup, although the pointed-to pages
@@ -618,16 +609,10 @@ static ControlFileData *ControlFile = NULL;
/*
* XLogRecPtrToBufIdx returns the index of the WAL buffer that holds, or
* would hold if it was in cache, the page containing 'recptr'.
- *
- * XLogRecEndPtrToBufIdx is the same, but a pointer to the first byte of a
- * page is taken to mean the previous page.
*/
#define XLogRecPtrToBufIdx(recptr) \
(((recptr) / XLOG_BLCKSZ) % (XLogCtl->XLogCacheBlck + 1))
-#define XLogRecEndPtrToBufIdx(recptr) \
- ((((recptr) - 1) / XLOG_BLCKSZ) % (XLogCtl->XLogCacheBlck + 1))
-
/*
* These are the number of bytes in a WAL page and segment usable for WAL data.
*/
@@ -2409,9 +2394,9 @@ AdvanceXLInsertBuffer(XLogRecPtr upto, bool opportunistic)
* Now that we have the lock, check if someone initialized the page
* already.
*/
- while (upto >= XLogCtl->xlblocks[XLogCtl->curridx] || opportunistic)
+ while (upto >= XLogCtl->InitializedUpTo || opportunistic)
{
- nextidx = NextBufIdx(XLogCtl->curridx);
+ nextidx = XLogRecPtrToBufIdx(XLogCtl->InitializedUpTo);
/*
* Get ending-offset of the buffer page we need to replace (this may
@@ -2484,11 +2469,9 @@ AdvanceXLInsertBuffer(XLogRecPtr upto, bool opportunistic)
* Now the next buffer slot is free and we can set it up to be the next
* output page.
*/
- NewPageBeginPtr = XLogCtl->xlblocks[XLogCtl->curridx];
+ NewPageBeginPtr = XLogCtl->InitializedUpTo;
NewPageEndPtr = NewPageBeginPtr + XLOG_BLCKSZ;
- Assert(NewPageEndPtr % XLOG_BLCKSZ == 0);
- Assert(XLogRecEndPtrToBufIdx(NewPageEndPtr) == nextidx);
Assert(XLogRecPtrToBufIdx(NewPageBeginPtr) == nextidx);
NewPage = (XLogPageHeader) (XLogCtl->pages + nextidx * (Size) XLOG_BLCKSZ);
@@ -2547,7 +2530,7 @@ AdvanceXLInsertBuffer(XLogRecPtr upto, bool opportunistic)
*((volatile XLogRecPtr *) &XLogCtl->xlblocks[nextidx]) = NewPageEndPtr;
- XLogCtl->curridx = nextidx;
+ XLogCtl->InitializedUpTo = NewPageEndPtr;
npages++;
}
@@ -2598,7 +2581,6 @@ XLogCheckpointNeeded(XLogSegNo new_segno)
static void
XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
{
- XLogCtlWrite *Write = &XLogCtl->Write;
bool ispartialpage;
bool last_iteration;
bool finishing_seg;
@@ -2631,12 +2613,10 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
/*
* Within the loop, curridx is the cache block index of the page to
- * consider writing. We advance Write->curridx only after successfully
- * writing pages. (Right now, this refinement is useless since we are
- * going to PANIC if any error occurs anyway; but someday it may come in
- * useful.)
+ * consider writing. Begin at the buffer containing the next unwritten
+ * page, or last partially written page.
*/
- curridx = Write->curridx;
+ curridx = XLogRecPtrToBufIdx(LogwrtResult.Write);
while (LogwrtResult.Write < WriteRqst.Write)
{
@@ -2747,7 +2727,6 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
/* Update state for write */
openLogOff += nbytes;
- Write->curridx = ispartialpage ? curridx : NextBufIdx(curridx);
npages = 0;
/*
@@ -2775,7 +2754,7 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
if (XLogArchivingActive())
XLogArchiveNotifySeg(openLogSegNo);
- Write->lastSegSwitchTime = (pg_time_t) time(NULL);
+ XLogCtl->lastSegSwitchTime = (pg_time_t) time(NULL);
/*
* Request a checkpoint if we've consumed too much xlog since
@@ -2807,7 +2786,6 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
}
Assert(npages == 0);
- Assert(curridx == Write->curridx);
/*
* If asked to flush, do so
@@ -6021,12 +5999,10 @@ StartupXLOG(void)
XLogSegNo endLogSegNo;
TimeLineID PrevTimeLineID;
XLogRecord *record;
- uint32 freespace;
TransactionId oldestActiveXID;
bool backupEndRequired = false;
bool backupFromStandby = false;
DBState dbstate_at_startup;
- int firstIdx;
XLogReaderState *xlogreader;
XLogPageReadPrivate private;
bool fast_promoted = false;
@@ -7034,48 +7010,51 @@ StartupXLOG(void)
openLogOff = 0;
Insert = &XLogCtl->Insert;
Insert->PrevBytePos = XLogRecPtrToBytePos(LastRec);
-
- firstIdx = XLogRecEndPtrToBufIdx(EndOfLog);
- XLogCtl->curridx = firstIdx;
-
- XLogCtl->xlblocks[firstIdx] = ((EndOfLog - 1) / XLOG_BLCKSZ + 1) * XLOG_BLCKSZ;
+ Insert->CurrBytePos = XLogRecPtrToBytePos(EndOfLog);
/*
* Tricky point here: readBuf contains the *last* block that the LastRec
* record spans, not the one it starts in. The last block is indeed the
* one we want to use.
*/
- Assert(readOff == (XLogCtl->xlblocks[firstIdx] - XLOG_BLCKSZ) % XLogSegSize);
- memcpy((char *) &XLogCtl->pages[firstIdx * XLOG_BLCKSZ], xlogreader->readBuf, XLOG_BLCKSZ);
- Insert->CurrBytePos = XLogRecPtrToBytePos(EndOfLog);
+ if (EndOfLog % XLOG_BLCKSZ != 0)
+ {
+ char *page;
+ int len;
+ int firstIdx;
+ XLogRecPtr pageBeginPtr;
- LogwrtResult.Write = LogwrtResult.Flush = EndOfLog;
+ pageBeginPtr = EndOfLog - (EndOfLog % XLOG_BLCKSZ);
+ Assert(readOff == pageBeginPtr % XLogSegSize);
- XLogCtl->LogwrtResult = LogwrtResult;
+ firstIdx = XLogRecPtrToBufIdx(EndOfLog);
- XLogCtl->LogwrtRqst.Write = EndOfLog;
- XLogCtl->LogwrtRqst.Flush = EndOfLog;
+ /* Copy the valid part of the last block, and zero the rest */
+ page = &XLogCtl->pages[firstIdx * XLOG_BLCKSZ];
+ len = EndOfLog % XLOG_BLCKSZ;
+ memcpy(page, xlogreader->readBuf, len);
+ memset(page + len, 0, XLOG_BLCKSZ - len);
- freespace = INSERT_FREESPACE(EndOfLog);
- if (freespace > 0)
- {
- /* Make sure rest of page is zero */
- MemSet(&XLogCtl->pages[firstIdx * XLOG_BLCKSZ] + EndOfLog % XLOG_BLCKSZ, 0, freespace);
- XLogCtl->Write.curridx = firstIdx;
+ XLogCtl->xlblocks[firstIdx] = pageBeginPtr + XLOG_BLCKSZ;
+ XLogCtl->InitializedUpTo = pageBeginPtr + XLOG_BLCKSZ;
}
else
{
/*
- * Whenever LogwrtResult points to exactly the end of a page,
- * Write.curridx must point to the *next* page (see XLogWrite()).
- *
- * Note: it might seem we should do AdvanceXLInsertBuffer() here, but
- * this is sufficient. The first actual attempt to insert a log
- * record will advance the insert state.
+ * There is no partial block to copy. Just set InitializedUpTo,
+ * and let the first attempt to insert a log record to initialize
+ * the next buffer.
*/
- XLogCtl->Write.curridx = NextBufIdx(firstIdx);
+ XLogCtl->InitializedUpTo = EndOfLog;
}
+ LogwrtResult.Write = LogwrtResult.Flush = EndOfLog;
+
+ XLogCtl->LogwrtResult = LogwrtResult;
+
+ XLogCtl->LogwrtRqst.Write = EndOfLog;
+ XLogCtl->LogwrtRqst.Flush = EndOfLog;
+
/* Pre-scan prepared transactions to find out the range of XIDs present */
oldestActiveXID = PrescanPreparedTransactions(NULL, NULL);
@@ -7199,7 +7178,7 @@ StartupXLOG(void)
LWLockRelease(ControlFileLock);
/* start the archive_timeout timer running */
- XLogCtl->Write.lastSegSwitchTime = (pg_time_t) time(NULL);
+ XLogCtl->lastSegSwitchTime = (pg_time_t) time(NULL);
/* also initialize latestCompletedXid, to nextXid - 1 */
LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
@@ -7710,7 +7689,7 @@ GetLastSegSwitchTime(void)
/* Need WALWriteLock, but shared lock is sufficient */
LWLockAcquire(WALWriteLock, LW_SHARED);
- result = XLogCtl->Write.lastSegSwitchTime;
+ result = XLogCtl->lastSegSwitchTime;
LWLockRelease(WALWriteLock);
return result;