Re: Remove page-read callback from XLogReaderState. - Mailing list pgsql-hackers
| From | Kyotaro Horiguchi |
|---|---|
| Subject | Re: Remove page-read callback from XLogReaderState. |
| Date | |
| Msg-id | 20200526.164002.822446651247617415.horikyota.ntt@gmail.com Whole thread Raw |
| In response to | Re: Remove page-read callback from XLogReaderState. (Kyotaro Horiguchi <horikyota.ntt@gmail.com>) |
| Responses |
Re: Remove page-read callback from XLogReaderState.
|
| List | pgsql-hackers |
At Wed, 22 Apr 2020 10:12:46 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote in
> cd12323440 conflicts with this. Rebased.
b060dbe000 is conflicting. I gave up isolating XLogOpenSegment from
xlogreader.c, since the two are tightly coupled than I thought.
This patch removes all the three callbacks (open/close/page_read) in
XL_ROUTINE from XLogReaderState. It only has "cleanup" callback
instead.
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center
From fd04ff06de3ab7bcc36f0c80fff42452e49e0259 Mon Sep 17 00:00:00 2001
From: Kyotaro Horiguchi <horiguchi.kyotaro@lab.ntt.co.jp>
Date: Thu, 5 Sep 2019 20:21:55 +0900
Subject: [PATCH v10 1/4] Move callback-call from ReadPageInternal to
XLogReadRecord.
The current WAL record reader reads page data using a call back
function. Although it is not so problematic alone, it would be a
problem if we are going to do add tasks like encryption which is
performed on page data before WAL reader reads them. To avoid that the
record reader facility has to have a new code path corresponds to
every new callback, this patch separates page reader from WAL record
reading facility by modifying the current WAL record reader to a state
machine.
As the first step of that change, this patch moves the page reader
function out of ReadPageInternal, then the remaining tasks of the
function are taken over by the new function XLogNeedData. As the
result XLogPageRead directly calls the page reader callback function
according to the feedback from XLogNeedData.
---
src/backend/access/transam/xlog.c | 16 +-
src/backend/access/transam/xlogreader.c | 281 ++++++++++++++----------
src/backend/access/transam/xlogutils.c | 12 +-
src/backend/replication/walsender.c | 10 +-
src/bin/pg_rewind/parsexlog.c | 21 +-
src/bin/pg_waldump/pg_waldump.c | 8 +-
src/include/access/xlogreader.h | 25 ++-
src/include/access/xlogutils.h | 2 +-
8 files changed, 222 insertions(+), 153 deletions(-)
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index ca09d81b08..da468598e4 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -909,7 +909,7 @@ static bool InstallXLogFileSegment(XLogSegNo *segno, char *tmppath,
static int XLogFileRead(XLogSegNo segno, int emode, TimeLineID tli,
XLogSource source, bool notfoundOk);
static int XLogFileReadAnyTLI(XLogSegNo segno, int emode, XLogSource source);
-static int XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
+static bool XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
int reqLen, XLogRecPtr targetRecPtr, char *readBuf);
static bool WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
bool fetching_ckpt, XLogRecPtr tliRecPtr);
@@ -4329,7 +4329,6 @@ ReadRecord(XLogReaderState *xlogreader, int emode,
XLogRecord *record;
XLogPageReadPrivate *private = (XLogPageReadPrivate *) xlogreader->private_data;
- /* Pass through parameters to XLogPageRead */
private->fetching_ckpt = fetching_ckpt;
private->emode = emode;
private->randAccess = (xlogreader->ReadRecPtr == InvalidXLogRecPtr);
@@ -11854,7 +11853,7 @@ CancelBackup(void)
* XLogPageRead() to try fetching the record from another source, or to
* sleep and retry.
*/
-static int
+static bool
XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr, int reqLen,
XLogRecPtr targetRecPtr, char *readBuf)
{
@@ -11913,7 +11912,8 @@ retry:
readLen = 0;
readSource = XLOG_FROM_ANY;
- return -1;
+ xlogreader->readLen = -1;
+ return false;
}
}
@@ -12008,7 +12008,8 @@ retry:
goto next_record_is_invalid;
}
- return readLen;
+ xlogreader->readLen = readLen;
+ return true;
next_record_is_invalid:
lastSourceFailed = true;
@@ -12022,8 +12023,9 @@ next_record_is_invalid:
/* In standby-mode, keep trying */
if (StandbyMode)
goto retry;
- else
- return -1;
+
+ xlogreader->readLen = -1;
+ return false;
}
/*
diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index 5995798b58..399bad0603 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -36,8 +36,8 @@
static void report_invalid_record(XLogReaderState *state, const char *fmt,...)
pg_attribute_printf(2, 3);
static bool allocate_recordbuf(XLogReaderState *state, uint32 reclength);
-static int ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr,
- int reqLen);
+static bool XLogNeedData(XLogReaderState *state, XLogRecPtr pageptr,
+ int reqLen, bool header_inclusive);
static void XLogReaderInvalReadState(XLogReaderState *state);
static bool ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess);
@@ -274,7 +274,6 @@ XLogReadRecord(XLogReaderState *state, char **errormsg)
uint32 targetRecOff;
uint32 pageHeaderSize;
bool gotheader;
- int readOff;
/*
* randAccess indicates whether to verify the previous-record pointer of
@@ -324,14 +323,20 @@ XLogReadRecord(XLogReaderState *state, char **errormsg)
* 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 < 0)
+ while (XLogNeedData(state, targetPagePtr,
+ Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ),
+ targetRecOff != 0))
+ {
+ if (!state->routine.page_read(state, state->readPagePtr, state->readLen,
+ RecPtr, state->readBuf))
+ break;
+ }
+
+ if (!state->page_verified)
goto err;
/*
- * ReadPageInternal always returns at least the page header, so we can
- * examine it now.
+ * We have at least the page header, so we can examine it now.
*/
pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
if (targetRecOff == 0)
@@ -357,8 +362,8 @@ XLogReadRecord(XLogReaderState *state, char **errormsg)
goto err;
}
- /* ReadPageInternal has verified the page header */
- Assert(pageHeaderSize <= readOff);
+ /* XLogNeedData has verified the page header */
+ Assert(pageHeaderSize <= state->readLen);
/*
* Read the record length.
@@ -431,18 +436,27 @@ XLogReadRecord(XLogReaderState *state, char **errormsg)
do
{
+ int rest_len = total_len - gotlen;
+
/* 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));
+ while (XLogNeedData(state, targetPagePtr,
+ Min(rest_len, XLOG_BLCKSZ),
+ false))
+ {
+ if (!state->routine.page_read(state, state->readPagePtr,
+ state->readLen,
+ state->ReadRecPtr,
+ state->readBuf))
+ break;
+ }
- if (readOff < 0)
+ if (!state->page_verified)
goto err;
- Assert(SizeOfXLogShortPHD <= readOff);
+ Assert(SizeOfXLogShortPHD <= state->readLen);
/* Check that the continuation on next page looks valid */
pageHeader = (XLogPageHeader) state->readBuf;
@@ -471,21 +485,14 @@ XLogReadRecord(XLogReaderState *state, char **errormsg)
/* Append the continuation from this page to the buffer */
pageHeaderSize = XLogPageHeaderSize(pageHeader);
- if (readOff < pageHeaderSize)
- readOff = ReadPageInternal(state, targetPagePtr,
- pageHeaderSize);
-
- Assert(pageHeaderSize <= readOff);
+ Assert(pageHeaderSize <= state->readLen);
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);
-
+ Assert (pageHeaderSize + len <= state->readLen);
memcpy(buffer, (char *) contdata, len);
buffer += len;
gotlen += len;
@@ -515,9 +522,16 @@ XLogReadRecord(XLogReaderState *state, char **errormsg)
else
{
/* Wait for the record data to become available */
- readOff = ReadPageInternal(state, targetPagePtr,
- Min(targetRecOff + total_len, XLOG_BLCKSZ));
- if (readOff < 0)
+ while (XLogNeedData(state, targetPagePtr,
+ Min(targetRecOff + total_len, XLOG_BLCKSZ), true))
+ {
+ if (!state->routine.page_read(state, state->readPagePtr,
+ state->readLen,
+ state->ReadRecPtr, state->readBuf))
+ break;
+ }
+
+ if (!state->page_verified)
goto err;
/* Record does not cross a page boundary */
@@ -560,109 +574,138 @@ err:
}
/*
- * Read a single xlog page including at least [pageptr, reqLen] of valid data
- * via the page_read() callback.
+ * Checks that an xlog page loaded in state->readBuf is including at least
+ * [pageptr, reqLen] and the page is valid. header_inclusive indicates that
+ * reqLen is calculated including page header length.
*
- * Returns -1 if the required page cannot be read for some reason; errormsg_buf
- * is set in that case (unless the error occurs in the page_read callback).
+ * Returns false if the buffer already contains the requested data, or found
+ * error. state->page_verified is set to true for the former and false for the
+ * latter.
*
- * We fetch the page from a reader-local cache if we know we have the required
- * data and if there hasn't been any error since caching the data.
+ * Otherwise returns true and requests data loaded onto state->readBuf by
+ * state->readPagePtr and state->readLen. The caller shall call this function
+ * again after filling the buffer at least with that portion of data and set
+ * state->readLen to the length of actually loaded data.
+ *
+ * If header_inclusive is false, corrects reqLen internally by adding the
+ * actual page header length and may request caller for new data.
*/
-static int
-ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
+static bool
+XLogNeedData(XLogReaderState *state, XLogRecPtr pageptr, int reqLen,
+ bool header_inclusive)
{
- int readLen;
uint32 targetPageOff;
XLogSegNo targetSegNo;
- XLogPageHeader hdr;
+ uint32 addLen = 0;
- Assert((pageptr % XLOG_BLCKSZ) == 0);
+ /* Some data is loaded, but page header is not verified yet. */
+ if (!state->page_verified &&
+ !XLogRecPtrIsInvalid(state->readPagePtr) && state->readLen >= 0)
+ {
+ uint32 pageHeaderSize;
+ /* just loaded new data so needs to verify page header */
+
+ /* The caller must have loaded at least page header */
+ Assert (state->readLen >= SizeOfXLogShortPHD);
+
+ /*
+ * We have enough data to check the header length. Recheck the loaded
+ * length against the actual header length.
+ */
+ pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
+
+ /* Request more data if we don't have the full header. */
+ if (state->readLen < pageHeaderSize)
+ {
+ state->readLen = pageHeaderSize;
+ return true;
+ }
+
+ /* Now that we know we have the full header, validate it. */
+ if (!XLogReaderValidatePageHeader(state, state->readPagePtr,
+ (char *) state->readBuf))
+ {
+ /* That's bad. Force reading the page again. */
+ XLogReaderInvalReadState(state);
+
+ return false;
+ }
+
+ state->page_verified = true;
+
+ XLByteToSeg(state->readPagePtr, state->seg.ws_segno,
+ state->segcxt.ws_segsize);
+ }
+
+ /*
+ * The loaded page may not be the one caller is supposing to read when we
+ * are verifying the first page of new segment. In that case, skip further
+ * verification and immediately load the target page.
+ */
+ if (state->page_verified && pageptr == state->readPagePtr)
+ {
+ /*
+ * calculate additional length for page header keeping the total
+ * length within the block size.
+ */
+ if (!header_inclusive)
+ {
+ uint32 pageHeaderSize =
+ XLogPageHeaderSize((XLogPageHeader) state->readBuf);
+
+ addLen = pageHeaderSize;
+ if (reqLen + pageHeaderSize <= XLOG_BLCKSZ)
+ addLen = pageHeaderSize;
+ else
+ addLen = XLOG_BLCKSZ - reqLen;
+
+ Assert(addLen >= 0);
+ }
+
+ /* Return if we already have it. */
+ if (reqLen + addLen <= state->readLen)
+ return false;
+ }
+
+ /* Data is not in our buffer, request the caller for it. */
XLByteToSeg(pageptr, targetSegNo, state->segcxt.ws_segsize);
targetPageOff = XLogSegmentOffset(pageptr, state->segcxt.ws_segsize);
+ Assert((pageptr % XLOG_BLCKSZ) == 0);
- /* check whether we have all the requested data already */
- if (targetSegNo == state->seg.ws_segno &&
- targetPageOff == state->segoff && reqLen <= state->readLen)
- return state->readLen;
+ /*
+ * Every time we request to load new data of a page to the caller, even if
+ * we looked at a part of it before, we need to do verification on the next
+ * invocation as the caller might now be rereading data from a different
+ * source.
+ */
+ state->page_verified = false;
/*
- * 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.
+ * Don't do this if the caller requested the first page in the segment.
*/
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 < 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;
+ /*
+ * Then we'll see that the targetSegNo now matches the ws_segno, and
+ * will not come back here, but will request the actual target page.
+ */
+ state->readPagePtr = pageptr - targetPageOff;
+ state->readLen = XLOG_BLCKSZ;
+ return true;
}
/*
- * First, read the requested data length, but at least a short page header
- * so that we can validate it.
+ * Request the caller to load the page. We need 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 < 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 < 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:
- XLogReaderInvalReadState(state);
- return -1;
+ state->readPagePtr = pageptr;
+ state->readLen = Max(reqLen + addLen, SizeOfXLogShortPHD);
+ return true;
}
/*
@@ -671,9 +714,7 @@ err:
static void
XLogReaderInvalReadState(XLogReaderState *state)
{
- state->seg.ws_segno = 0;
- state->segoff = 0;
- state->readLen = 0;
+ state->readPagePtr = InvalidXLogRecPtr;
}
/*
@@ -954,7 +995,6 @@ XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
XLogRecPtr targetPagePtr;
int targetRecOff;
uint32 pageHeaderSize;
- int readLen;
/*
* Compute targetRecOff. It should typically be equal or greater than
@@ -962,7 +1002,7 @@ XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
* 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
+ * XLogNeedData() is prepared to handle that and will read at
* least short page-header worth of data
*/
targetRecOff = tmpRecPtr % XLOG_BLCKSZ;
@@ -970,19 +1010,24 @@ XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
/* scroll back to page boundary */
targetPagePtr = tmpRecPtr - targetRecOff;
- /* Read the page containing the record */
- readLen = ReadPageInternal(state, targetPagePtr, targetRecOff);
- if (readLen < 0)
+ while(XLogNeedData(state, targetPagePtr, targetRecOff,
+ targetRecOff != 0))
+ {
+ if (!state->routine.page_read(state, state->readPagePtr,
+ state->readLen,
+ state->ReadRecPtr, state->readBuf))
+ break;
+ }
+
+ if (!state->page_verified)
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;
+ /* we should have read the page header */
+ Assert (state->readLen >= pageHeaderSize);
/* skip over potential continuation data */
if (header->xlp_info & XLP_FIRST_IS_CONTRECORD)
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 322b0e8ff5..1b10b6df20 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -689,8 +689,8 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
void
XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wantLength)
{
- const XLogRecPtr lastReadPage = (state->seg.ws_segno *
- state->segcxt.ws_segsize + state->segoff);
+ const XLogRecPtr lastReadPage = state->seg.ws_segno *
+ state->segcxt.ws_segsize + state->readLen;
Assert(wantPage != InvalidXLogRecPtr && wantPage % XLOG_BLCKSZ == 0);
Assert(wantLength <= XLOG_BLCKSZ);
@@ -828,7 +828,7 @@ wal_segment_close(XLogReaderState *state)
* exists for normal backends, so we have to do a check/sleep/repeat style of
* loop for now.
*/
-int
+bool
read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr,
int reqLen, XLogRecPtr targetRecPtr, char *cur_page)
{
@@ -930,7 +930,8 @@ read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr,
else if (targetPagePtr + reqLen > read_upto)
{
/* not enough data there */
- return -1;
+ state->readLen = -1;
+ return false;
}
else
{
@@ -948,7 +949,8 @@ read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr,
WALReadRaiseError(&errinfo);
/* number of valid bytes in the buffer */
- return count;
+ state->readLen = count;
+ return true;
}
/*
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 86847cbb54..d3a94d611f 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -815,7 +815,7 @@ StartReplication(StartReplicationCmd *cmd)
* which has to do a plain sleep/busy loop, because the walsender's latch gets
* set every time WAL is flushed.
*/
-static int
+static bool
logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
XLogRecPtr targetRecPtr, char *cur_page)
{
@@ -835,7 +835,10 @@ logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int req
/* fail if not (implies we are going to shut down) */
if (flushptr < targetPagePtr + reqLen)
- return -1;
+ {
+ state->readLen = -1;
+ return false;
+ }
if (targetPagePtr + XLOG_BLCKSZ <= flushptr)
count = XLOG_BLCKSZ; /* more than one block available */
@@ -863,7 +866,8 @@ logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int req
XLByteToSeg(targetPagePtr, segno, state->segcxt.ws_segsize);
CheckXLogRemoved(segno, state->seg.ws_tli);
- return count;
+ state->readLen = count;
+ return true;
}
/*
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index d637f5eb77..907db33b9e 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -46,7 +46,7 @@ typedef struct XLogPageReadPrivate
int tliIndex;
} XLogPageReadPrivate;
-static int SimpleXLogPageRead(XLogReaderState *xlogreader,
+static bool SimpleXLogPageRead(XLogReaderState *xlogreader,
XLogRecPtr targetPagePtr,
int reqLen, XLogRecPtr targetRecPtr, char *readBuf);
@@ -236,7 +236,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
}
/* XLogReader callback function, to read a WAL page */
-static int
+static bool
SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
int reqLen, XLogRecPtr targetRecPtr, char *readBuf)
{
@@ -296,7 +296,8 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
if (private->restoreCommand == NULL)
{
pg_log_error("could not open file \"%s\": %m", xlogfpath);
- return -1;
+ xlogreader->readLen = -1;
+ return false;
}
/*
@@ -309,7 +310,10 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
private->restoreCommand);
if (xlogreadfd < 0)
- return -1;
+ {
+ xlogreader->readLen = -1;
+ return false;
+ }
else
pg_log_debug("using file \"%s\" restored from archive",
xlogfpath);
@@ -325,7 +329,8 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
if (lseek(xlogreadfd, (off_t) targetPageOff, SEEK_SET) < 0)
{
pg_log_error("could not seek in file \"%s\": %m", xlogfpath);
- return -1;
+ xlogreader->readLen = -1;
+ return false;
}
@@ -338,13 +343,15 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
pg_log_error("could not read file \"%s\": read %d of %zu",
xlogfpath, r, (Size) XLOG_BLCKSZ);
- return -1;
+ xlogreader->readLen = -1;
+ return false;
}
Assert(targetSegNo == xlogreadsegno);
xlogreader->seg.ws_tli = targetHistory[private->tliIndex].tli;
- return XLOG_BLCKSZ;
+ xlogreader->readLen = XLOG_BLCKSZ;
+ return true;
}
/*
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index d1a0678935..ab0c28d9b7 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -331,7 +331,7 @@ WALDumpCloseSegment(XLogReaderState *state)
}
/* pg_waldump's XLogReaderRoutine->page_read callback */
-static int
+static bool
WALDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
XLogRecPtr targetPtr, char *readBuff)
{
@@ -348,7 +348,8 @@ WALDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
else
{
private->endptr_reached = true;
- return -1;
+ state->readLen = -1;
+ return false;
}
}
@@ -373,7 +374,8 @@ WALDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
(Size) errinfo.wre_req);
}
- return count;
+ state->readLen = count;
+ return true;
}
/*
diff --git a/src/include/access/xlogreader.h b/src/include/access/xlogreader.h
index c21b0ba972..53e4212ac4 100644
--- a/src/include/access/xlogreader.h
+++ b/src/include/access/xlogreader.h
@@ -57,8 +57,8 @@ typedef struct WALSegmentContext
typedef struct XLogReaderState XLogReaderState;
-/* Function type definitions for various xlogreader interactions */
-typedef int (*XLogPageReadCB) (XLogReaderState *xlogreader,
+/* Function type definition for the read_page callback */
+typedef bool (*XLogPageReadCB) (XLogReaderState *xlogreader,
XLogRecPtr targetPagePtr,
int reqLen,
XLogRecPtr targetRecPtr,
@@ -175,6 +175,20 @@ struct XLogReaderState
XLogRecPtr ReadRecPtr; /* start of last record read */
XLogRecPtr EndRecPtr; /* end+1 of last record read */
+ /* ----------------------------------------
+ * Communication with page reader
+ * readBuf is XLOG_BLCKSZ bytes, valid up to at least readLen bytes.
+ * ----------------------------------------
+ */
+ /* variables to communicate with page reader */
+ XLogRecPtr readPagePtr; /* page pointer to read */
+ int32 readLen; /* bytes requested to reader, or actual bytes
+ * read by reader, which must be larger than
+ * the request, or -1 on error */
+ TimeLineID readPageTLI; /* TLI for data currently in readBuf */
+ char *readBuf; /* buffer to store data */
+ bool page_verified; /* is the page on the buffer verified? */
+
/* ----------------------------------------
* Decoded representation of current record
@@ -201,13 +215,6 @@ struct XLogReaderState
* ----------------------------------------
*/
- /*
- * Buffer for currently read page (XLOG_BLCKSZ bytes, valid up to at least
- * readLen bytes)
- */
- char *readBuf;
- uint32 readLen;
-
/* last read XLOG position for data currently in readBuf */
WALSegmentContext segcxt;
WALOpenSegment seg;
diff --git a/src/include/access/xlogutils.h b/src/include/access/xlogutils.h
index e59b6cf3a9..c287edf206 100644
--- a/src/include/access/xlogutils.h
+++ b/src/include/access/xlogutils.h
@@ -47,7 +47,7 @@ extern Buffer XLogReadBufferExtended(RelFileNode rnode, ForkNumber forknum,
extern Relation CreateFakeRelcacheEntry(RelFileNode rnode);
extern void FreeFakeRelcacheEntry(Relation fakerel);
-extern int read_local_xlog_page(XLogReaderState *state,
+extern bool read_local_xlog_page(XLogReaderState *state,
XLogRecPtr targetPagePtr, int reqLen,
XLogRecPtr targetRecPtr, char *cur_page);
extern void wal_segment_open(XLogReaderState *state,
--
2.18.2
From f057f47e030cf6cf8a94e5b82237f6c95afa8f20 Mon Sep 17 00:00:00 2001
From: Kyotaro Horiguchi <horiguchi.kyotaro@lab.ntt.co.jp>
Date: Tue, 10 Sep 2019 12:58:27 +0900
Subject: [PATCH v10 2/4] Move page-reader out of XLogReadRecord
This is the second step of removing callbacks from WAL record reader.
Since it is essential to take in additional data while reading a
record, the function have to ask caller for new data while keeping
working state. Thus the function is turned into a state machine.
---
src/backend/access/transam/twophase.c | 15 +-
src/backend/access/transam/xlog.c | 58 +-
src/backend/access/transam/xlogreader.c | 700 +++++++++++-------
src/backend/access/transam/xlogutils.c | 17 +-
src/backend/replication/logical/logical.c | 26 +-
.../replication/logical/logicalfuncs.c | 13 +-
src/backend/replication/slotfuncs.c | 18 +-
src/backend/replication/walsender.c | 47 +-
src/bin/pg_rewind/parsexlog.c | 84 +--
src/bin/pg_waldump/pg_waldump.c | 36 +-
src/include/access/xlogreader.h | 121 ++-
src/include/access/xlogutils.h | 4 +-
src/include/replication/logical.h | 11 +-
13 files changed, 656 insertions(+), 494 deletions(-)
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index e1904877fa..8630ad2032 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -1330,11 +1330,8 @@ XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len)
XLogReaderState *xlogreader;
char *errormsg;
- xlogreader = XLogReaderAllocate(wal_segment_size, NULL,
- XL_ROUTINE(.page_read = &read_local_xlog_page,
- .segment_open = &wal_segment_open,
- .segment_close = &wal_segment_close),
- NULL);
+ xlogreader = XLogReaderAllocate(wal_segment_size, NULL, wal_segment_close);
+
if (!xlogreader)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
@@ -1342,7 +1339,13 @@ XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len)
errdetail("Failed while allocating a WAL reading processor.")));
XLogBeginRead(xlogreader, lsn);
- record = XLogReadRecord(xlogreader, &errormsg);
+ while (XLogReadRecord(xlogreader, &record, &errormsg) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!read_local_xlog_page(xlogreader))
+ break;
+ }
+
if (record == NULL)
ereport(ERROR,
(errcode_for_file_access(),
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index da468598e4..840218efee 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -828,13 +828,6 @@ static XLogSource currentSource = XLOG_FROM_ANY;
static bool lastSourceFailed = false;
static bool pendingWalRcvRestart = false;
-typedef struct XLogPageReadPrivate
-{
- int emode;
- bool fetching_ckpt; /* are we fetching a checkpoint record? */
- bool randAccess;
-} XLogPageReadPrivate;
-
/*
* These variables track when we last obtained some WAL data to process,
* and where we got it from. (XLogReceiptSource is initially the same as
@@ -909,8 +902,8 @@ static bool InstallXLogFileSegment(XLogSegNo *segno, char *tmppath,
static int XLogFileRead(XLogSegNo segno, int emode, TimeLineID tli,
XLogSource source, bool notfoundOk);
static int XLogFileReadAnyTLI(XLogSegNo segno, int emode, XLogSource source);
-static bool XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
- int reqLen, XLogRecPtr targetRecPtr, char *readBuf);
+static bool XLogPageRead(XLogReaderState *xlogreader,
+ bool fetching_ckpt, int emode, bool randAccess);
static bool WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
bool fetching_ckpt, XLogRecPtr tliRecPtr);
static int emode_for_corrupt_record(int emode, XLogRecPtr RecPtr);
@@ -1222,8 +1215,7 @@ XLogInsertRecord(XLogRecData *rdata,
appendBinaryStringInfo(&recordBuf, rdata->data, rdata->len);
if (!debug_reader)
- debug_reader = XLogReaderAllocate(wal_segment_size, NULL,
- XL_ROUTINE(), NULL);
+ debug_reader = XLogReaderAllocate(wal_segment_size, NULL NULL);
if (!debug_reader)
{
@@ -4323,15 +4315,10 @@ CleanupBackupHistory(void)
* record is available.
*/
static XLogRecord *
-ReadRecord(XLogReaderState *xlogreader, int emode,
- bool fetching_ckpt)
+ReadRecord(XLogReaderState *xlogreader, int emode, bool fetching_ckpt)
{
XLogRecord *record;
- XLogPageReadPrivate *private = (XLogPageReadPrivate *) xlogreader->private_data;
-
- private->fetching_ckpt = fetching_ckpt;
- private->emode = emode;
- private->randAccess = (xlogreader->ReadRecPtr == InvalidXLogRecPtr);
+ bool randAccess = (xlogreader->ReadRecPtr == InvalidXLogRecPtr);
/* This is the first attempt to read this page. */
lastSourceFailed = false;
@@ -4339,8 +4326,16 @@ ReadRecord(XLogReaderState *xlogreader, int emode,
for (;;)
{
char *errormsg;
+ XLogReadRecordResult result;
+
+ while ((result = XLogReadRecord(xlogreader, &record, &errormsg))
+ == XLREAD_NEED_DATA)
+ {
+ if (!XLogPageRead(xlogreader, fetching_ckpt, emode, randAccess))
+ break;
+
+ }
- record = XLogReadRecord(xlogreader, &errormsg);
ReadRecPtr = xlogreader->ReadRecPtr;
EndRecPtr = xlogreader->EndRecPtr;
if (record == NULL)
@@ -6317,7 +6312,6 @@ StartupXLOG(void)
bool backupFromStandby = false;
DBState dbstate_at_startup;
XLogReaderState *xlogreader;
- XLogPageReadPrivate private;
bool fast_promoted = false;
struct stat st;
@@ -6477,13 +6471,9 @@ StartupXLOG(void)
OwnLatch(&XLogCtl->recoveryWakeupLatch);
/* Set up XLOG reader facility */
- MemSet(&private, 0, sizeof(XLogPageReadPrivate));
xlogreader =
- XLogReaderAllocate(wal_segment_size, NULL,
- XL_ROUTINE(.page_read = &XLogPageRead,
- .segment_open = NULL,
- .segment_close = wal_segment_close),
- &private);
+ XLogReaderAllocate(wal_segment_size, NULL, wal_segment_close);
+
if (!xlogreader)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
@@ -11854,12 +11844,13 @@ CancelBackup(void)
* sleep and retry.
*/
static bool
-XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr, int reqLen,
- XLogRecPtr targetRecPtr, char *readBuf)
+XLogPageRead(XLogReaderState *xlogreader,
+ bool fetching_ckpt, int emode, bool randAccess)
{
- XLogPageReadPrivate *private =
- (XLogPageReadPrivate *) xlogreader->private_data;
- int emode = private->emode;
+ char *readBuf = xlogreader->readBuf;
+ XLogRecPtr targetPagePtr = xlogreader->readPagePtr;
+ int reqLen = xlogreader->readLen;
+ XLogRecPtr targetRecPtr = xlogreader->ReadRecPtr;
uint32 targetPageOff;
XLogSegNo targetSegNo PG_USED_FOR_ASSERTS_ONLY;
int r;
@@ -11902,8 +11893,8 @@ retry:
flushedUpto < targetPagePtr + reqLen))
{
if (!WaitForWALToBecomeAvailable(targetPagePtr + reqLen,
- private->randAccess,
- private->fetching_ckpt,
+ randAccess,
+ fetching_ckpt,
targetRecPtr))
{
if (readFile >= 0)
@@ -12008,6 +11999,7 @@ retry:
goto next_record_is_invalid;
}
+ Assert(xlogreader->readPagePtr == targetPagePtr);
xlogreader->readLen = readLen;
return true;
diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index 399bad0603..bdde75086c 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -40,7 +40,7 @@ static bool XLogNeedData(XLogReaderState *state, XLogRecPtr pageptr,
int reqLen, bool header_inclusive);
static void XLogReaderInvalReadState(XLogReaderState *state);
static bool ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
- XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess);
+ XLogRecPtr PrevRecPtr, XLogRecord *record);
static bool ValidXLogRecord(XLogReaderState *state, XLogRecord *record,
XLogRecPtr recptr);
static void ResetDecoder(XLogReaderState *state);
@@ -71,7 +71,7 @@ report_invalid_record(XLogReaderState *state, const char *fmt,...)
*/
XLogReaderState *
XLogReaderAllocate(int wal_segment_size, const char *waldir,
- XLogReaderRoutine *routine, void *private_data)
+ WALSegmentCleanupCB cleanup_cb)
{
XLogReaderState *state;
@@ -82,7 +82,7 @@ XLogReaderAllocate(int wal_segment_size, const char *waldir,
return NULL;
/* initialize caller-provided support functions */
- state->routine = *routine;
+ state->cleanup_cb = cleanup_cb;
state->max_block_id = -1;
@@ -105,8 +105,6 @@ XLogReaderAllocate(int wal_segment_size, const char *waldir,
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);
@@ -138,8 +136,8 @@ XLogReaderFree(XLogReaderState *state)
{
int block_id;
- if (state->seg.ws_file != -1)
- state->routine.segment_close(state);
+ if (state->seg.ws_file >= 0)
+ state->cleanup_cb(state);
for (block_id = 0; block_id <= XLR_MAX_BLOCK_ID; block_id++)
{
@@ -244,6 +242,7 @@ XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr)
/* Begin at the passed-in record pointer. */
state->EndRecPtr = RecPtr;
state->ReadRecPtr = InvalidXLogRecPtr;
+ state->readRecordState = XLREAD_NEXT_RECORD;
}
/*
@@ -252,317 +251,452 @@ XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr)
* XLogBeginRead() or XLogFindNextRecord() must be called before the first call
* to XLogReadRecord().
*
- * If the page_read callback fails to read the requested data, NULL is
- * returned. The callback is expected to have reported the error; errormsg
- * is set to NULL.
+ * This function may return XLREAD_NEED_DATA several times before returning a
+ * result record. The caller shall read in some new data then call this
+ * function again with the same parameters.
*
- * If the reading fails for some other reason, NULL is also returned, and
- * *errormsg is set to a string with details of the failure.
+ * When a record is successfully read, returns XLREAD_SUCCESS with result
+ * record being stored in *record. Otherwise *record is NULL.
*
- * The returned pointer (or *errormsg) points to an internal buffer that's
- * valid until the next call to XLogReadRecord.
+ * Returns XLREAD_NEED_DATA if more data is needed to finish reading the
+ * current record. In that case, state->readPagePtr and state->readLen inform
+ * the desired position and minimum length of data needed. The caller shall
+ * read in the requested data and set state->readBuf to point to a buffer
+ * containing it. The caller must also set state->readPageTLI and
+ * state->readLen to indicate the timeline that it was read from, and the
+ * length of data that is now available (which must be >= given readLen),
+ * respectively.
+ *
+ * If invalid data is encountered, returns XLREAD_FAIL with *record being set to
+ * NULL. *errormsg is set to a string with details of the failure.
+ * The returned pointer (or *errormsg) points to an internal buffer that's valid
+ * until the next call to XLogReadRecord.
+ *
+ *
+ * This function runs a state machine consists of the following states.
+ *
+ * XLREAD_NEXT_RECORD :
+ * The initial state, if called with valid RecPtr, try to read a record at
+ * that position. If invalid RecPtr is given try to read a record just after
+ * the last one previously read.
+ * This state ens after setting ReadRecPtr. Then goes to XLREAD_TOT_LEN.
+ *
+ * XLREAD_TOT_LEN:
+ * Examining record header. Ends after reading record total
+ * length. recordRemainLen and recordGotLen are initialized.
+ *
+ * XLREAD_FIRST_FRAGMENT:
+ * Reading the first fragment. Ends with finishing reading a single
+ * record. Goes to XLREAD_NEXT_RECORD if that's all or
+ * XLREAD_CONTINUATION if we have continuation.
+
+ * XLREAD_CONTINUATION:
+ * Reading continuation of record. Ends with finishing the whole record then
+ * goes to XLREAD_NEXT_RECORD. During this state, recordRemainLen indicates
+ * how much is left and readRecordBuf holds the partially assert
+ * record.recordContRecPtr points to the beginning of the next page where to
+ * continue.
+ *
+ * If wrong data found in any state, the state machine stays at the current
+ * state. This behavior allows to continue reading a reacord switching among
+ * different souces, while streaming replication.
*/
-XLogRecord *
-XLogReadRecord(XLogReaderState *state, char **errormsg)
+XLogReadRecordResult
+XLogReadRecord(XLogReaderState *state, XLogRecord **record, char **errormsg)
{
- XLogRecPtr RecPtr;
- XLogRecord *record;
- XLogRecPtr targetPagePtr;
- bool randAccess;
- uint32 len,
- total_len;
- uint32 targetRecOff;
- uint32 pageHeaderSize;
- bool gotheader;
+ XLogRecord *prec;
- /*
- * 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;
+ *record = NULL;
/* reset error state */
*errormsg = NULL;
state->errormsg_buf[0] = '\0';
- ResetDecoder(state);
-
- RecPtr = state->EndRecPtr;
-
- if (state->ReadRecPtr != InvalidXLogRecPtr)
- {
- /* read the record after the one we just read */
-
- /*
- * EndRecPtr 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, EndRecPtr should already be pointing to a valid
- * record starting position.
- */
- Assert(XRecOffIsValid(RecPtr));
- randAccess = true;
- }
-
- state->currRecPtr = RecPtr;
-
- 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.
- */
- while (XLogNeedData(state, targetPagePtr,
- Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ),
- targetRecOff != 0))
- {
- if (!state->routine.page_read(state, state->readPagePtr, state->readLen,
- RecPtr, state->readBuf))
- break;
- }
-
- if (!state->page_verified)
- goto err;
-
- /*
- * We have 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",
- (uint32) (RecPtr >> 32), (uint32) 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",
- (uint32) (RecPtr >> 32), (uint32) RecPtr);
- goto err;
- }
-
- /* XLogNeedData has verified the page header */
- Assert(pageHeaderSize <= state->readLen);
-
- /*
- * 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->ReadRecPtr, 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",
- (uint32) (RecPtr >> 32), (uint32) RecPtr,
- (uint32) SizeOfXLogRecord, total_len);
- goto err;
- }
- gotheader = false;
- }
-
- len = XLOG_BLCKSZ - RecPtr % XLOG_BLCKSZ;
- if (total_len > len)
+ switch (state->readRecordState)
{
- /* Need to reassemble record */
- char *contdata;
- XLogPageHeader pageHeader;
- char *buffer;
- uint32 gotlen;
-
- /*
- * 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,
- (uint32) (RecPtr >> 32), (uint32) RecPtr);
- goto err;
- }
+ case XLREAD_NEXT_RECORD:
+ ResetDecoder(state);
- /* 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
- {
- int rest_len = total_len - gotlen;
-
- /* Calculate pointer to beginning of next page */
- targetPagePtr += XLOG_BLCKSZ;
-
- /* Wait for the next page to become available */
- while (XLogNeedData(state, targetPagePtr,
- Min(rest_len, XLOG_BLCKSZ),
- false))
+ if (state->ReadRecPtr != InvalidXLogRecPtr)
{
- if (!state->routine.page_read(state, state->readPagePtr,
- state->readLen,
- state->ReadRecPtr,
- state->readBuf))
- break;
+ /* read the record after the one we just read */
+
+ /*
+ * EndRecPtr 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.
+ */
+ state->PrevRecPtr = state->ReadRecPtr;
+ state->ReadRecPtr = state->EndRecPtr;
+ }
+ else
+ {
+ /*
+ * Caller supplied a position to start at.
+ *
+ * In this case, EndRecPtr should already be pointing to a
+ * valid record starting position.
+ */
+ Assert(XRecOffIsValid(state->EndRecPtr));
+ state->ReadRecPtr = state->EndRecPtr;
+
+ /*
+ * We cannot verify the previous-record pointer when we're
+ * seeking to a particular record. Reset PrevRecPtr so that we
+ * won't try doing that.
+ */
+ state->PrevRecPtr = InvalidXLogRecPtr;
+ state->EndRecPtr = InvalidXLogRecPtr; /* to be tidy */
}
+ state->record_verified = false;
+ state->readRecordState = XLREAD_TOT_LEN;
+ /* fall through */
+
+ case XLREAD_TOT_LEN:
+ {
+ uint32 total_len;
+ uint32 pageHeaderSize;
+ XLogRecPtr targetPagePtr;
+ uint32 targetRecOff;
+ XLogPageHeader pageHeader;
+
+ targetPagePtr =
+ state->ReadRecPtr - (state->ReadRecPtr % XLOG_BLCKSZ);
+ targetRecOff = state->ReadRecPtr % XLOG_BLCKSZ;
+
+ /*
+ * Check if we have enough data. For the first record in the page,
+ * the requesting length doesn't contain page header.
+ */
+ if (XLogNeedData(state, targetPagePtr,
+ Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ),
+ targetRecOff != 0))
+ return XLREAD_NEED_DATA;
+
+ /* error out if caller supplied bogus page */
if (!state->page_verified)
goto err;
- Assert(SizeOfXLogShortPHD <= state->readLen);
+ /* examine page header now. */
+ pageHeaderSize =
+ XLogPageHeaderSize((XLogPageHeader) state->readBuf);
+ if (targetRecOff == 0)
+ {
+ /* At page start, so skip over page header. */
+ state->ReadRecPtr += pageHeaderSize;
+ targetRecOff = pageHeaderSize;
+ }
+ else if (targetRecOff < pageHeaderSize)
+ {
+ report_invalid_record(state, "invalid record offset at %X/%X",
+ (uint32) (state->ReadRecPtr >> 32),
+ (uint32) state->ReadRecPtr);
+ goto err;
+ }
- /* Check that the continuation on next page looks valid */
pageHeader = (XLogPageHeader) state->readBuf;
- if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD))
+ if ((pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
+ targetRecOff == pageHeaderSize)
{
- report_invalid_record(state,
- "there is no contrecord flag at %X/%X",
- (uint32) (RecPtr >> 32), (uint32) RecPtr);
+ report_invalid_record(state, "contrecord is requested by %X/%X",
+ (uint32) (state->ReadRecPtr >> 32),
+ (uint32) state->ReadRecPtr);
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 at %X/%X",
- pageHeader->xlp_rem_len,
- (uint32) (RecPtr >> 32), (uint32) RecPtr);
- goto err;
- }
-
- /* Append the continuation from this page to the buffer */
- pageHeaderSize = XLogPageHeaderSize(pageHeader);
-
+ /* XLogNeedData has verified the page header */
Assert(pageHeaderSize <= state->readLen);
- contdata = (char *) state->readBuf + pageHeaderSize;
- len = XLOG_BLCKSZ - pageHeaderSize;
- if (pageHeader->xlp_rem_len < len)
- len = pageHeader->xlp_rem_len;
+ /*
+ * 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.
+ */
+ prec = (XLogRecord *) (state->readBuf +
+ state->ReadRecPtr % XLOG_BLCKSZ);
+ total_len = prec->xl_tot_len;
- Assert (pageHeaderSize + len <= state->readLen);
- memcpy(buffer, (char *) contdata, len);
- buffer += len;
- gotlen += 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 XLREAD_CONTINUATION state below;
+ * otherwise we might fail to apply ValidXLogRecordHeader at all.
+ */
+ if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord)
+ {
+ if (!ValidXLogRecordHeader(state, state->ReadRecPtr,
+ state->PrevRecPtr, prec))
+ goto err;
- /* If we just reassembled the record header, validate it. */
- if (!gotheader)
+ state->record_verified = true;
+ }
+ else
{
- record = (XLogRecord *) state->readRecordBuf;
- if (!ValidXLogRecordHeader(state, RecPtr, state->ReadRecPtr,
- record, randAccess))
+ /* 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",
+ (uint32) (state->ReadRecPtr >> 32),
+ (uint32) state->ReadRecPtr,
+ (uint32) SizeOfXLogRecord, total_len);
goto err;
- gotheader = true;
+ }
}
- } while (gotlen < total_len);
-
- Assert(gotheader);
- record = (XLogRecord *) state->readRecordBuf;
- if (!ValidXLogRecord(state, record, RecPtr))
- goto err;
+ /*
+ * Wait for the rest of the record, or the part of the record that
+ * fit on the first page if crossed a page boundary, to become
+ * available.
+ */
+ state->recordGotLen = 0;
+ state->recordRemainLen = total_len;
+ state->readRecordState = XLREAD_FIRST_FRAGMENT;
+ }
+ /* fall through */
- pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
- state->ReadRecPtr = RecPtr;
- state->EndRecPtr = targetPagePtr + pageHeaderSize
- + MAXALIGN(pageHeader->xlp_rem_len);
- }
- else
- {
- /* Wait for the record data to become available */
- while (XLogNeedData(state, targetPagePtr,
- Min(targetRecOff + total_len, XLOG_BLCKSZ), true))
+ case XLREAD_FIRST_FRAGMENT:
{
- if (!state->routine.page_read(state, state->readPagePtr,
- state->readLen,
- state->ReadRecPtr, state->readBuf))
+ uint32 total_len = state->recordRemainLen;
+ uint32 request_len;
+ uint32 record_len;
+ XLogRecPtr targetPagePtr;
+ uint32 targetRecOff;
+
+ /*
+ * Wait for the rest of the record on the first page to become
+ * available
+ */
+ targetPagePtr =
+ state->ReadRecPtr - (state->ReadRecPtr % XLOG_BLCKSZ);
+ targetRecOff = state->ReadRecPtr % XLOG_BLCKSZ;
+
+ request_len = Min(targetRecOff + total_len, XLOG_BLCKSZ);
+ record_len = request_len - targetRecOff;
+
+ /* ReadRecPtr contains page header */
+ Assert (targetRecOff != 0);
+ if (XLogNeedData(state, targetPagePtr, request_len, true))
+ return XLREAD_NEED_DATA;
+
+ /* error out if caller supplied bogus page */
+ if (!state->page_verified)
+ goto err;
+
+ prec = (XLogRecord *) (state->readBuf + targetRecOff);
+
+ /* validate record header if not yet */
+ if (!state->record_verified && record_len >= SizeOfXLogRecord)
+ {
+ if (!ValidXLogRecordHeader(state, state->ReadRecPtr,
+ state->PrevRecPtr, prec))
+ goto err;
+
+ state->record_verified = true;
+ }
+
+
+ if (total_len == record_len)
+ {
+ /* Record does not cross a page boundary */
+ Assert(state->record_verified);
+
+ if (!ValidXLogRecord(state, prec, state->ReadRecPtr))
+ goto err;
+
+ state->record_verified = true; /* to be tidy */
+
+ /* We already checked the header earlier */
+ state->EndRecPtr = state->ReadRecPtr + MAXALIGN(record_len);
+
+ *record = prec;
+ state->readRecordState = XLREAD_NEXT_RECORD;
break;
+ }
+
+ /*
+ * The record continues on the next page. Need to reassemble
+ * record
+ */
+ Assert(total_len > record_len);
+
+ /* 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,
+ (uint32) (state->ReadRecPtr >> 32),
+ (uint32) state->ReadRecPtr);
+ goto err;
+ }
+
+ /* Copy the first fragment of the record from the first page. */
+ memcpy(state->readRecordBuf, state->readBuf + targetRecOff,
+ record_len);
+ state->recordGotLen += record_len;
+ state->recordRemainLen -= record_len;
+
+ /* Calculate pointer to beginning of next page */
+ state->recordContRecPtr = state->ReadRecPtr + record_len;
+ Assert(state->recordContRecPtr % XLOG_BLCKSZ == 0);
+
+ state->readRecordState = XLREAD_CONTINUATION;
}
+ /* fall through */
+
+ case XLREAD_CONTINUATION:
+ {
+ XLogPageHeader pageHeader;
+ uint32 pageHeaderSize;
+ XLogRecPtr targetPagePtr;
+
+ /* we enter this state only if we haven't read the whole record. */
+ Assert (state->recordRemainLen > 0);
+
+ while(state->recordRemainLen > 0)
+ {
+ char *contdata;
+ uint32 request_len;
+ uint32 record_len;
+
+ /* Wait for the next page to become available */
+ targetPagePtr = state->recordContRecPtr;
+
+ /* this request contains page header */
+ Assert (targetPagePtr != 0);
+ if (XLogNeedData(state, targetPagePtr,
+ Min(state->recordRemainLen, XLOG_BLCKSZ),
+ false))
+ return XLREAD_NEED_DATA;
+
+ if (!state->page_verified)
+ goto err;
+
+ Assert(SizeOfXLogShortPHD <= state->readLen);
- if (!state->page_verified)
- goto err;
+ /* Check that the continuation on next page looks valid */
+ pageHeader = (XLogPageHeader) state->readBuf;
+ if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD))
+ {
+ report_invalid_record(
+ state,
+ "there is no contrecord flag at %X/%X reading %X/%X",
+ (uint32) (state->recordContRecPtr >> 32),
+ (uint32) state->recordContRecPtr,
+ (uint32) (state->ReadRecPtr >> 32),
+ (uint32) state->ReadRecPtr);
+ goto err;
+ }
- /* Record does not cross a page boundary */
- if (!ValidXLogRecord(state, record, 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 ||
+ pageHeader->xlp_rem_len != state->recordRemainLen)
+ {
+ report_invalid_record(
+ state,
+ "invalid contrecord length %u at %X/%X reading %X/%X, expected %u",
+ pageHeader->xlp_rem_len,
+ (uint32) (state->recordContRecPtr >> 32),
+ (uint32) state->recordContRecPtr,
+ (uint32) (state->ReadRecPtr >> 32),
+ (uint32) state->ReadRecPtr,
+ state->recordRemainLen);
+ goto err;
+ }
- state->EndRecPtr = RecPtr + MAXALIGN(total_len);
+ /* Append the continuation from this page to the buffer */
+ pageHeaderSize = XLogPageHeaderSize(pageHeader);
- state->ReadRecPtr = RecPtr;
+ /*
+ * XLogNeedData should have ensured that the whole page header
+ * was read
+ */
+ Assert(state->readLen >= pageHeaderSize);
+
+ contdata = (char *) state->readBuf + pageHeaderSize;
+ record_len = XLOG_BLCKSZ - pageHeaderSize;
+ if (pageHeader->xlp_rem_len < record_len)
+ record_len = pageHeader->xlp_rem_len;
+
+ request_len = record_len + pageHeaderSize;
+
+ /* XLogNeedData should have ensured all needed data was read */
+ Assert (state->readLen >= request_len);
+
+ memcpy(state->readRecordBuf + state->recordGotLen,
+ (char *) contdata, record_len);
+ state->recordGotLen += record_len;
+ state->recordRemainLen -= record_len;
+
+ /* If we just reassembled the record header, validate it. */
+ if (!state->record_verified)
+ {
+ Assert(state->recordGotLen >= SizeOfXLogRecord);
+ if (!ValidXLogRecordHeader(state, state->ReadRecPtr,
+ state->PrevRecPtr,
+ (XLogRecord *) state->readRecordBuf))
+ goto err;
+
+ state->record_verified = true;
+ }
+
+ /* Calculate pointer to beginning of next page, and continue */
+ state->recordContRecPtr += XLOG_BLCKSZ;
+ }
+
+ /* targetPagePtr is pointing the last-read page here */
+ prec = (XLogRecord *) state->readRecordBuf;
+ if (!ValidXLogRecord(state, prec, state->ReadRecPtr))
+ goto err;
+
+ pageHeaderSize =
+ XLogPageHeaderSize((XLogPageHeader) state->readBuf);
+ state->EndRecPtr = targetPagePtr + pageHeaderSize
+ + MAXALIGN(pageHeader->xlp_rem_len);
+
+ *record = prec;
+ state->readRecordState = XLREAD_NEXT_RECORD;
+ break;
+ }
}
/*
* Special processing if it's an XLOG SWITCH record
*/
- if (record->xl_rmid == RM_XLOG_ID &&
- (record->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH)
+ if ((*record)->xl_rmid == RM_XLOG_ID &&
+ ((*record)->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH)
{
/* Pretend it extends to end of segment */
state->EndRecPtr += state->segcxt.ws_segsize - 1;
state->EndRecPtr -= XLogSegmentOffset(state->EndRecPtr, state->segcxt.ws_segsize);
}
- if (DecodeXLogRecord(state, record, errormsg))
- return record;
- else
- return NULL;
+ Assert (!*record || state->readLen >= 0);
+ if (DecodeXLogRecord(state, *record, errormsg))
+ return XLREAD_SUCCESS;
+
+ *record = NULL;
+ return XLREAD_FAIL;
err:
/*
- * Invalidate the read state. We might read from a different source after
+ * Invalidate the read page. We might read from a different source after
* failure.
*/
XLogReaderInvalReadState(state);
@@ -570,7 +704,8 @@ err:
if (state->errormsg_buf[0] != '\0')
*errormsg = state->errormsg_buf;
- return NULL;
+ *record = NULL;
+ return XLREAD_FAIL;
}
/*
@@ -722,11 +857,12 @@ XLogReaderInvalReadState(XLogReaderState *state)
*
* This is just a convenience subroutine to avoid duplicated code in
* XLogReadRecord. It's not intended for use from anywhere else.
+ *
+ * If PrevRecPtr is valid, the xl_prev is is cross-checked with it.
*/
static bool
ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
- XLogRecPtr PrevRecPtr, XLogRecord *record,
- bool randAccess)
+ XLogRecPtr PrevRecPtr, XLogRecord *record)
{
if (record->xl_tot_len < SizeOfXLogRecord)
{
@@ -744,7 +880,7 @@ ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
(uint32) RecPtr);
return false;
}
- if (randAccess)
+ if (PrevRecPtr == InvalidXLogRecPtr)
{
/*
* We can't exactly verify the prev-link, but surely it should be less
@@ -976,11 +1112,14 @@ XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr,
* XLogReadRecord() will read the next valid record.
*/
XLogRecPtr
-XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
+XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr,
+ XLogFindNextRecordCB read_page, void *private)
{
XLogRecPtr tmpRecPtr;
XLogRecPtr found = InvalidXLogRecPtr;
XLogPageHeader header;
+ XLogRecord *record;
+ XLogReadRecordResult result;
char *errormsg;
Assert(!XLogRecPtrIsInvalid(RecPtr));
@@ -1013,9 +1152,7 @@ XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
while(XLogNeedData(state, targetPagePtr, targetRecOff,
targetRecOff != 0))
{
- if (!state->routine.page_read(state, state->readPagePtr,
- state->readLen,
- state->ReadRecPtr, state->readBuf))
+ if (!read_page(state, private))
break;
}
@@ -1067,8 +1204,16 @@ XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
* or we just jumped over the remaining data of a continuation.
*/
XLogBeginRead(state, tmpRecPtr);
- while (XLogReadRecord(state, &errormsg) != NULL)
+ while ((result = XLogReadRecord(state, &record, &errormsg)) !=
+ XLREAD_FAIL)
{
+ if (result == XLREAD_NEED_DATA)
+ {
+ if (!read_page(state, private))
+ goto err;
+ continue;
+ }
+
/* past the record we've found, break out */
if (RecPtr <= state->ReadRecPtr)
{
@@ -1088,9 +1233,9 @@ err:
#endif /* FRONTEND */
/*
- * Helper function to ease writing of XLogRoutine->page_read callbacks.
- * If this function is used, caller must supply a segment_open callback in
- * 'state', as that is used here.
+ * Helper function to ease writing of page_read callback.
+ * If this function is used, caller must supply a segment_open callback and
+ * segment_close callback as that is used here.
*
* Read 'count' bytes into 'buf', starting at location 'startptr', from WAL
* fetched from timeline 'tli'.
@@ -1103,6 +1248,7 @@ err:
*/
bool
WALRead(XLogReaderState *state,
+ WALSegmentOpenCB segopenfn, WALSegmentCloseCB segclosefn,
char *buf, XLogRecPtr startptr, Size count, TimeLineID tli,
WALReadError *errinfo)
{
@@ -1134,10 +1280,10 @@ WALRead(XLogReaderState *state,
XLogSegNo nextSegNo;
if (state->seg.ws_file >= 0)
- state->routine.segment_close(state);
+ segclosefn(state);
XLByteToSeg(recptr, nextSegNo, state->segcxt.ws_segsize);
- state->routine.segment_open(state, nextSegNo, &tli);
+ segopenfn(state, nextSegNo, &tli);
/* This shouldn't happen -- indicates a bug in segment_open */
Assert(state->seg.ws_file >= 0);
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 1b10b6df20..303333571f 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -689,8 +689,7 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
void
XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wantLength)
{
- const XLogRecPtr lastReadPage = state->seg.ws_segno *
- state->segcxt.ws_segsize + state->readLen;
+ const XLogRecPtr lastReadPage = state->readPagePtr;
Assert(wantPage != InvalidXLogRecPtr && wantPage % XLOG_BLCKSZ == 0);
Assert(wantLength <= XLOG_BLCKSZ);
@@ -705,7 +704,7 @@ XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wa
* current TLI has since become historical.
*/
if (lastReadPage == wantPage &&
- state->readLen != 0 &&
+ state->page_verified &&
lastReadPage + state->readLen >= wantPage + Min(wantLength, XLOG_BLCKSZ - 1))
return;
@@ -792,6 +791,7 @@ wal_segment_open(XLogReaderState *state, XLogSegNo nextSegNo,
char path[MAXPGPATH];
XLogFilePath(path, tli, nextSegNo, state->segcxt.ws_segsize);
+ elog(LOG, "HOGE: %lu, %d => %s", nextSegNo, tli, path);
state->seg.ws_file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
if (state->seg.ws_file >= 0)
return;
@@ -829,9 +829,11 @@ wal_segment_close(XLogReaderState *state)
* loop for now.
*/
bool
-read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr,
- int reqLen, XLogRecPtr targetRecPtr, char *cur_page)
+read_local_xlog_page(XLogReaderState *state)
{
+ XLogRecPtr targetPagePtr = state->readPagePtr;
+ int reqLen = state->readLen;
+ char *cur_page = state->readBuf;
XLogRecPtr read_upto,
loc;
TimeLineID tli;
@@ -944,11 +946,12 @@ read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr,
* as 'count', read the whole page anyway. It's guaranteed to be
* zero-padded up to the page boundary if it's incomplete.
*/
- if (!WALRead(state, cur_page, targetPagePtr, XLOG_BLCKSZ, tli,
- &errinfo))
+ if (!WALRead(state, wal_segment_open, wal_segment_close,
+ cur_page, targetPagePtr, XLOG_BLCKSZ, tli, &errinfo))
WALReadRaiseError(&errinfo);
/* number of valid bytes in the buffer */
+ state->readPagePtr = targetPagePtr;
state->readLen = count;
return true;
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc69e5ce5f..d99474c173 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -120,7 +120,8 @@ StartupDecodingContext(List *output_plugin_options,
TransactionId xmin_horizon,
bool need_full_snapshot,
bool fast_forward,
- XLogReaderRoutine *xl_routine,
+ LogicalDecodingXLogPageReadCB page_read,
+ WALSegmentCleanupCB cleanup_cb,
LogicalOutputPluginWriterPrepareWrite prepare_write,
LogicalOutputPluginWriterWrite do_write,
LogicalOutputPluginWriterUpdateProgress update_progress)
@@ -169,11 +170,12 @@ StartupDecodingContext(List *output_plugin_options,
ctx->slot = slot;
- ctx->reader = XLogReaderAllocate(wal_segment_size, NULL, xl_routine, ctx);
+ ctx->reader = XLogReaderAllocate(wal_segment_size, NULL, cleanup_cb);
if (!ctx->reader)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
+ ctx->page_read = page_read;
ctx->reorder = ReorderBufferAllocate();
ctx->snapshot_builder =
@@ -231,7 +233,8 @@ CreateInitDecodingContext(char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
XLogRecPtr restart_lsn,
- XLogReaderRoutine *xl_routine,
+ LogicalDecodingXLogPageReadCB page_read,
+ WALSegmentCleanupCB cleanup_cb,
LogicalOutputPluginWriterPrepareWrite prepare_write,
LogicalOutputPluginWriterWrite do_write,
LogicalOutputPluginWriterUpdateProgress update_progress)
@@ -328,7 +331,7 @@ CreateInitDecodingContext(char *plugin,
ctx = StartupDecodingContext(NIL, restart_lsn, xmin_horizon,
need_full_snapshot, false,
- xl_routine, prepare_write, do_write,
+ page_read, cleanup_cb, prepare_write, do_write,
update_progress);
/* call output plugin initialization callback */
@@ -376,7 +379,8 @@ LogicalDecodingContext *
CreateDecodingContext(XLogRecPtr start_lsn,
List *output_plugin_options,
bool fast_forward,
- XLogReaderRoutine *xl_routine,
+ LogicalDecodingXLogPageReadCB page_read,
+ WALSegmentCleanupCB cleanup_cb,
LogicalOutputPluginWriterPrepareWrite prepare_write,
LogicalOutputPluginWriterWrite do_write,
LogicalOutputPluginWriterUpdateProgress update_progress)
@@ -429,8 +433,8 @@ CreateDecodingContext(XLogRecPtr start_lsn,
ctx = StartupDecodingContext(output_plugin_options,
start_lsn, InvalidTransactionId, false,
- fast_forward, xl_routine, prepare_write,
- do_write, update_progress);
+ fast_forward, page_read, cleanup_cb,
+ prepare_write, do_write, update_progress);
/* call output plugin initialization callback */
old_context = MemoryContextSwitchTo(ctx->context);
@@ -483,7 +487,13 @@ DecodingContextFindStartpoint(LogicalDecodingContext *ctx)
char *err = NULL;
/* the read_page callback waits for new WAL */
- record = XLogReadRecord(ctx->reader, &err);
+ while (XLogReadRecord(ctx->reader, &record, &err) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!ctx->page_read(ctx->reader))
+ break;
+ }
+
if (err)
elog(ERROR, "%s", err);
if (!record)
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index b99c94e848..fcc81b358e 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -233,9 +233,8 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
ctx = CreateDecodingContext(InvalidXLogRecPtr,
options,
false,
- XL_ROUTINE(.page_read = read_local_xlog_page,
- .segment_open = wal_segment_open,
- .segment_close = wal_segment_close),
+ read_local_xlog_page,
+ wal_segment_close,
LogicalOutputPrepareWrite,
LogicalOutputWrite, NULL);
@@ -284,7 +283,13 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
XLogRecord *record;
char *errm = NULL;
- record = XLogReadRecord(ctx->reader, &errm);
+ while (XLogReadRecord(ctx->reader, &record, &errm) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!ctx->page_read(ctx->reader))
+ break;
+ }
+
if (errm)
elog(ERROR, "%s", errm);
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 6fed3cfd23..cac197045d 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -152,9 +152,8 @@ create_logical_replication_slot(char *name, char *plugin,
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
restart_lsn,
- XL_ROUTINE(.page_read = read_local_xlog_page,
- .segment_open = wal_segment_open,
- .segment_close = wal_segment_close),
+ read_local_xlog_page,
+ wal_segment_close,
NULL, NULL, NULL);
/*
@@ -465,9 +464,8 @@ pg_logical_replication_slot_advance(XLogRecPtr moveto)
ctx = CreateDecodingContext(InvalidXLogRecPtr,
NIL,
true, /* fast_forward */
- XL_ROUTINE(.page_read = read_local_xlog_page,
- .segment_open = wal_segment_open,
- .segment_close = wal_segment_close),
+ read_local_xlog_page,
+ wal_segment_close,
NULL, NULL, NULL);
/*
@@ -492,7 +490,13 @@ pg_logical_replication_slot_advance(XLogRecPtr moveto)
* Read records. No changes are generated in fast_forward mode,
* but snapbuilder/slot statuses are updated properly.
*/
- record = XLogReadRecord(ctx->reader, &errm);
+ while (XLogReadRecord(ctx->reader, &record, &errm) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!ctx->page_read(ctx->reader))
+ break;
+ }
+
if (errm)
elog(ERROR, "%s", errm);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index d3a94d611f..cc7e7fdac7 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -293,11 +293,9 @@ InitWalSender(void)
if (!am_db_walsender)
{
xlogreader = &fake_xlogreader;
- xlogreader->routine =
- *XL_ROUTINE(.segment_open = WalSndSegmentOpen,
- .segment_close = wal_segment_close);
WALOpenSegmentInit(&xlogreader->seg, &xlogreader->segcxt,
wal_segment_size, NULL);
+ xlogreader->cleanup_cb = wal_segment_close;
}
}
@@ -816,9 +814,11 @@ StartReplication(StartReplicationCmd *cmd)
* set every time WAL is flushed.
*/
static bool
-logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
- XLogRecPtr targetRecPtr, char *cur_page)
+logical_read_xlog_page(XLogReaderState *state)
{
+ XLogRecPtr targetPagePtr = state->readPagePtr;
+ int reqLen = state->readLen;
+ char *cur_page = state->readBuf;
XLogRecPtr flushptr;
int count;
WALReadError errinfo;
@@ -846,11 +846,11 @@ logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int req
count = flushptr - targetPagePtr; /* part of the page available */
/* now actually read the data, we know it's there */
- if (!WALRead(state,
+ if (!WALRead(state, WalSndSegmentOpen, wal_segment_close,
cur_page,
targetPagePtr,
XLOG_BLCKSZ,
- state->seg.ws_tli, /* Pass the current TLI because only
+ xlogreader->seg.ws_tli, /* Pass the current TLI because only
* WalSndSegmentOpen controls whether new
* TLI is needed. */
&errinfo))
@@ -863,8 +863,8 @@ logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int req
* read() succeeds in that case, but the data we tried to read might
* already have been overwritten with new WAL records.
*/
- XLByteToSeg(targetPagePtr, segno, state->segcxt.ws_segsize);
- CheckXLogRemoved(segno, state->seg.ws_tli);
+ XLByteToSeg(targetPagePtr, segno, xlogreader->segcxt.ws_segsize);
+ CheckXLogRemoved(segno, xlogreader->seg.ws_tli);
state->readLen = count;
return true;
@@ -1018,9 +1018,8 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
InvalidXLogRecPtr,
- XL_ROUTINE(.page_read = logical_read_xlog_page,
- .segment_open = WalSndSegmentOpen,
- .segment_close = wal_segment_close),
+ logical_read_xlog_page,
+ wal_segment_close,
WalSndPrepareWrite, WalSndWriteData,
WalSndUpdateProgress);
@@ -1183,9 +1182,8 @@ StartLogicalReplication(StartReplicationCmd *cmd)
*/
logical_decoding_ctx =
CreateDecodingContext(cmd->startpoint, cmd->options, false,
- XL_ROUTINE(.page_read = logical_read_xlog_page,
- .segment_open = WalSndSegmentOpen,
- .segment_close = wal_segment_close),
+ logical_read_xlog_page,
+ wal_segment_close,
WalSndPrepareWrite, WalSndWriteData,
WalSndUpdateProgress);
xlogreader = logical_decoding_ctx->reader;
@@ -2495,14 +2493,14 @@ WalSndSegmentOpen(XLogReaderState *state, XLogSegNo nextSegNo,
{
XLogSegNo endSegNo;
- XLByteToSeg(sendTimeLineValidUpto, endSegNo, state->segcxt.ws_segsize);
- if (state->seg.ws_segno == endSegNo)
+ XLByteToSeg(sendTimeLineValidUpto, endSegNo, xlogreader->segcxt.ws_segsize);
+ if (xlogreader->seg.ws_segno == endSegNo)
*tli_p = sendTimeLineNextTLI;
}
- XLogFilePath(path, *tli_p, nextSegNo, state->segcxt.ws_segsize);
- state->seg.ws_file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
- if (state->seg.ws_file >= 0)
+ XLogFilePath(path, *tli_p, nextSegNo, xlogreader->segcxt.ws_segsize);
+ xlogreader->seg.ws_file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
+ if (xlogreader->seg.ws_file >= 0)
return;
/*
@@ -2763,7 +2761,7 @@ XLogSendPhysical(void)
enlargeStringInfo(&output_message, nbytes);
retry:
- if (!WALRead(xlogreader,
+ if (!WALRead(xlogreader, WalSndSegmentOpen, wal_segment_close,
&output_message.data[output_message.len],
startptr,
nbytes,
@@ -2861,7 +2859,12 @@ XLogSendLogical(void)
*/
WalSndCaughtUp = false;
- record = XLogReadRecord(logical_decoding_ctx->reader, &errm);
+ while (XLogReadRecord(logical_decoding_ctx->reader, &record, &errm) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!logical_decoding_ctx->page_read(logical_decoding_ctx->reader))
+ break;
+ }
/* xlog record was invalid */
if (errm != NULL)
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 907db33b9e..cad8e13965 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -40,15 +40,9 @@ static int xlogreadfd = -1;
static XLogSegNo xlogreadsegno = -1;
static char xlogfpath[MAXPGPATH];
-typedef struct XLogPageReadPrivate
-{
- const char *restoreCommand;
- int tliIndex;
-} XLogPageReadPrivate;
-
-static bool SimpleXLogPageRead(XLogReaderState *xlogreader,
- XLogRecPtr targetPagePtr,
- int reqLen, XLogRecPtr targetRecPtr, char *readBuf);
+static bool SimpleXLogPageRead(XLogReaderState *xlogreader,
+ const char *datadir, int *tliIndex,
+ const char *restoreCommand);
/*
* Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
@@ -62,20 +56,22 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
XLogRecord *record;
XLogReaderState *xlogreader;
char *errormsg;
- XLogPageReadPrivate private;
- private.tliIndex = tliIndex;
- private.restoreCommand = restoreCommand;
- xlogreader = XLogReaderAllocate(WalSegSz, datadir,
- XL_ROUTINE(.page_read = &SimpleXLogPageRead),
- &private);
+ xlogreader = XLogReaderAllocate(WalSegSz, datadir, NULL);
+
if (xlogreader == NULL)
pg_fatal("out of memory");
XLogBeginRead(xlogreader, startpoint);
do
{
- record = XLogReadRecord(xlogreader, &errormsg);
+ while (XLogReadRecord(xlogreader, &record, &errormsg) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!SimpleXLogPageRead(xlogreader, datadir,
+ &tliIndex, restoreCommand))
+ break;
+ }
if (record == NULL)
{
@@ -113,19 +109,19 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex,
XLogRecord *record;
XLogReaderState *xlogreader;
char *errormsg;
- XLogPageReadPrivate private;
XLogRecPtr endptr;
- private.tliIndex = tliIndex;
- private.restoreCommand = restoreCommand;
- xlogreader = XLogReaderAllocate(WalSegSz, datadir,
- XL_ROUTINE(.page_read = &SimpleXLogPageRead),
- &private);
+ xlogreader = XLogReaderAllocate(WalSegSz, datadir, NULL);
if (xlogreader == NULL)
pg_fatal("out of memory");
XLogBeginRead(xlogreader, ptr);
- record = XLogReadRecord(xlogreader, &errormsg);
+ while (XLogReadRecord(xlogreader, &record, &errormsg) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!SimpleXLogPageRead(xlogreader, datadir, &tliIndex, restoreCommand))
+ break;
+ }
if (record == NULL)
{
if (errormsg)
@@ -160,7 +156,6 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
XLogRecPtr searchptr;
XLogReaderState *xlogreader;
char *errormsg;
- XLogPageReadPrivate private;
/*
* The given fork pointer points to the end of the last common record,
@@ -176,11 +171,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
forkptr += SizeOfXLogShortPHD;
}
- private.tliIndex = tliIndex;
- private.restoreCommand = restoreCommand;
- xlogreader = XLogReaderAllocate(WalSegSz, datadir,
- XL_ROUTINE(.page_read = &SimpleXLogPageRead),
- &private);
+ xlogreader = XLogReaderAllocate(WalSegSz, datadir, NULL);
if (xlogreader == NULL)
pg_fatal("out of memory");
@@ -190,7 +181,13 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
uint8 info;
XLogBeginRead(xlogreader, searchptr);
- record = XLogReadRecord(xlogreader, &errormsg);
+ while (XLogReadRecord(xlogreader, &record, &errormsg) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!SimpleXLogPageRead(xlogreader, datadir,
+ &tliIndex, restoreCommand))
+ break;
+ }
if (record == NULL)
{
@@ -237,10 +234,11 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
/* XLogReader callback function, to read a WAL page */
static bool
-SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
- int reqLen, XLogRecPtr targetRecPtr, char *readBuf)
+SimpleXLogPageRead(XLogReaderState *xlogreader, const char *datadir,
+ int *tliIndex, const char *restoreCommand)
{
- XLogPageReadPrivate *private = (XLogPageReadPrivate *) xlogreader->private_data;
+ XLogRecPtr targetPagePtr = xlogreader->readPagePtr;
+ char *readBuf = xlogreader->readBuf;
uint32 targetPageOff;
XLogRecPtr targetSegEnd;
XLogSegNo targetSegNo;
@@ -273,14 +271,14 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
* be done both forward and backward, consider also switching timeline
* accordingly.
*/
- while (private->tliIndex < targetNentries - 1 &&
- targetHistory[private->tliIndex].end < targetSegEnd)
- private->tliIndex++;
- while (private->tliIndex > 0 &&
- targetHistory[private->tliIndex].begin >= targetSegEnd)
- private->tliIndex--;
+ while (*tliIndex < targetNentries - 1 &&
+ targetHistory[*tliIndex].end < targetSegEnd)
+ (*tliIndex)++;
+ while (*tliIndex > 0 &&
+ targetHistory[*tliIndex].begin >= targetSegEnd)
+ (*tliIndex)--;
- XLogFileName(xlogfname, targetHistory[private->tliIndex].tli,
+ XLogFileName(xlogfname, targetHistory[*tliIndex].tli,
xlogreadsegno, WalSegSz);
snprintf(xlogfpath, MAXPGPATH, "%s/" XLOGDIR "/%s",
@@ -293,7 +291,7 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
/*
* If we have no restore_command to execute, then exit.
*/
- if (private->restoreCommand == NULL)
+ if (restoreCommand == NULL)
{
pg_log_error("could not open file \"%s\": %m", xlogfpath);
xlogreader->readLen = -1;
@@ -307,7 +305,7 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
xlogreadfd = RestoreArchivedFile(xlogreader->segcxt.ws_dir,
xlogfname,
WalSegSz,
- private->restoreCommand);
+ restoreCommand);
if (xlogreadfd < 0)
{
@@ -349,7 +347,7 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
Assert(targetSegNo == xlogreadsegno);
- xlogreader->seg.ws_tli = targetHistory[private->tliIndex].tli;
+ xlogreader->seg.ws_tli = targetHistory[*tliIndex].tli;
xlogreader->readLen = XLOG_BLCKSZ;
return true;
}
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index ab0c28d9b7..02e71138cc 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -330,12 +330,17 @@ WALDumpCloseSegment(XLogReaderState *state)
state->seg.ws_file = -1;
}
-/* pg_waldump's XLogReaderRoutine->page_read callback */
+/*
+ * pg_waldump's WAL page rader, also used as page_read callback for
+ * XLogFindNextRecord
+ */
static bool
-WALDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
- XLogRecPtr targetPtr, char *readBuff)
+WALDumpReadPage(XLogReaderState *state, void *priv)
{
- XLogDumpPrivate *private = state->private_data;
+ XLogRecPtr targetPagePtr = state->readPagePtr;
+ int reqLen = state->readLen;
+ char *readBuff = state->readBuf;
+ XLogDumpPrivate *private = (XLogDumpPrivate *) priv;
int count = XLOG_BLCKSZ;
WALReadError errinfo;
@@ -353,8 +358,8 @@ WALDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
}
}
- if (!WALRead(state, readBuff, targetPagePtr, count, private->timeline,
- &errinfo))
+ if (!WALRead(state, WALDumpOpenSegment, WALDumpCloseSegment,
+ readBuff, targetPagePtr, count, private->timeline, &errinfo))
{
WALOpenSegment *seg = &errinfo.wre_seg;
char fname[MAXPGPATH];
@@ -374,6 +379,7 @@ WALDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
(Size) errinfo.wre_req);
}
+ Assert(count >= state->readLen);
state->readLen = count;
return true;
}
@@ -1042,16 +1048,14 @@ main(int argc, char **argv)
/* we have everything we need, start reading */
xlogreader_state =
- XLogReaderAllocate(WalSegSz, waldir,
- XL_ROUTINE(.page_read = WALDumpReadPage,
- .segment_open = WALDumpOpenSegment,
- .segment_close = WALDumpCloseSegment),
- &private);
+ XLogReaderAllocate(WalSegSz, waldir, WALDumpCloseSegment);
+
if (!xlogreader_state)
fatal_error("out of memory");
/* first find a valid recptr to start from */
- first_record = XLogFindNextRecord(xlogreader_state, private.startptr);
+ first_record = XLogFindNextRecord(xlogreader_state, private.startptr,
+ &WALDumpReadPage, (void*) &private);
if (first_record == InvalidXLogRecPtr)
fatal_error("could not find a valid record after %X/%X",
@@ -1075,7 +1079,13 @@ main(int argc, char **argv)
for (;;)
{
/* try to read the next record */
- record = XLogReadRecord(xlogreader_state, &errormsg);
+ while (XLogReadRecord(xlogreader_state, &record, &errormsg) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!WALDumpReadPage(xlogreader_state, (void *) &private))
+ break;
+ }
+
if (!record)
{
if (!config.follow || private.endptr_reached)
diff --git a/src/include/access/xlogreader.h b/src/include/access/xlogreader.h
index 53e4212ac4..1d0167e26d 100644
--- a/src/include/access/xlogreader.h
+++ b/src/include/access/xlogreader.h
@@ -57,64 +57,15 @@ typedef struct WALSegmentContext
typedef struct XLogReaderState XLogReaderState;
-/* Function type definition for the read_page callback */
-typedef bool (*XLogPageReadCB) (XLogReaderState *xlogreader,
- XLogRecPtr targetPagePtr,
- int reqLen,
- XLogRecPtr targetRecPtr,
- char *readBuf);
+/* Function type definition for the segment cleanup callback */
+typedef void (*WALSegmentCleanupCB) (XLogReaderState *xlogreader);
+
+/* Function type definition for the open/close callbacks for WALRead() */
typedef void (*WALSegmentOpenCB) (XLogReaderState *xlogreader,
XLogSegNo nextSegNo,
TimeLineID *tli_p);
typedef void (*WALSegmentCloseCB) (XLogReaderState *xlogreader);
-typedef struct XLogReaderRoutine
-{
- /*
- * Data input callback
- *
- * This callback shall read at least reqLen valid bytes of the xlog page
- * starting at targetPagePtr, and store them in readBuf. The callback
- * shall return the number of bytes read (never more than XLOG_BLCKSZ), or
- * -1 on failure. The callback shall sleep, if necessary, to wait for the
- * requested bytes to become available. The callback will not be invoked
- * again for the same page unless more than the returned number of bytes
- * are needed.
- *
- * targetRecPtr is the position of the WAL record we're reading. Usually
- * it is equal to targetPagePtr + reqLen, but sometimes xlogreader needs
- * to read and verify the page or segment header, before it reads the
- * actual WAL record it's interested in. In that case, targetRecPtr can
- * be used to determine which timeline to read the page from.
- *
- * The callback shall set ->seg.ws_tli to the TLI of the file the page was
- * read from.
- */
- XLogPageReadCB page_read;
-
- /*
- * Callback to open the specified WAL segment for reading. ->seg.ws_file
- * shall be set to the file descriptor of the opened segment. In case of
- * failure, an error shall be raised by the callback and it shall not
- * return.
- *
- * "nextSegNo" is the number of the segment to be opened.
- *
- * "tli_p" is an input/output argument. WALRead() uses it to pass the
- * timeline in which the new segment should be found, but the callback can
- * use it to return the TLI that it actually opened.
- */
- WALSegmentOpenCB segment_open;
-
- /*
- * WAL segment close callback. ->seg.ws_file shall be set to a negative
- * number.
- */
- WALSegmentCloseCB segment_close;
-} XLogReaderRoutine;
-
-#define XL_ROUTINE(...) &(XLogReaderRoutine){__VA_ARGS__}
-
typedef struct
{
/* Is this block ref in use? */
@@ -144,12 +95,35 @@ typedef struct
uint16 data_bufsz;
} DecodedBkpBlock;
+/* Return code from XLogReadRecord */
+typedef enum XLogReadRecordResult
+{
+ XLREAD_SUCCESS, /* record is successfully read */
+ XLREAD_NEED_DATA, /* need more data. see XLogReadRecord. */
+ XLREAD_FAIL /* failed during reading a record */
+} XLogReadRecordResult;
+
+/*
+ * internal state of XLogReadRecord
+ *
+ * XLogReadState runs a state machine while reading a record. Theses states
+ * are not seen outside the function. Each state may repeat several times
+ * exiting requesting caller for new data. See the comment of XLogReadRecrod
+ * for details.
+ */
+typedef enum XLogReadRecordState {
+ XLREAD_NEXT_RECORD,
+ XLREAD_TOT_LEN,
+ XLREAD_FIRST_FRAGMENT,
+ XLREAD_CONTINUATION
+} XLogReadRecordState;
+
struct XLogReaderState
{
/*
* Operational callbacks
*/
- XLogReaderRoutine routine;
+ WALSegmentCleanupCB cleanup_cb;
/* ----------------------------------------
* Public parameters
@@ -162,18 +136,14 @@ struct XLogReaderState
*/
uint64 system_identifier;
- /*
- * Opaque data for callbacks to use. Not used by XLogReader.
- */
- void *private_data;
-
/*
* Start and end point of last record read. EndRecPtr is also used as the
* position to read next. Calling XLogBeginRead() sets EndRecPtr to the
* starting position and ReadRecPtr to invalid.
*/
- XLogRecPtr ReadRecPtr; /* start of last record read */
+ XLogRecPtr ReadRecPtr; /* start of last record read or being read */
XLogRecPtr EndRecPtr; /* end+1 of last record read */
+ XLogRecPtr PrevRecPtr; /* start of previous record read */
/* ----------------------------------------
* Communication with page reader
@@ -187,7 +157,9 @@ struct XLogReaderState
* the request, or -1 on error */
TimeLineID readPageTLI; /* TLI for data currently in readBuf */
char *readBuf; /* buffer to store data */
- bool page_verified; /* is the page on the buffer verified? */
+ bool page_verified; /* is the page header on the buffer verified? */
+ bool record_verified;/* is the current record header verified? */
+
/* ----------------------------------------
@@ -227,8 +199,6 @@ struct XLogReaderState
XLogRecPtr latestPagePtr;
TimeLineID latestPageTLI;
- /* beginning of the WAL record being read. */
- XLogRecPtr currRecPtr;
/* timeline to read it from, 0 if a lookup is required */
TimeLineID currTLI;
@@ -255,6 +225,15 @@ struct XLogReaderState
char *readRecordBuf;
uint32 readRecordBufSize;
+ /*
+ * XLogReadRecord() state
+ */
+ XLogReadRecordState readRecordState;/* state machine state */
+ int recordGotLen; /* amount of current record that has
+ * already been read */
+ int recordRemainLen; /* length of current record that remains */
+ XLogRecPtr recordContRecPtr; /* where the current record continues */
+
/* Buffer to hold error message */
char *errormsg_buf;
};
@@ -262,9 +241,7 @@ struct XLogReaderState
/* Get a new XLogReader */
extern XLogReaderState *XLogReaderAllocate(int wal_segment_size,
const char *waldir,
- XLogReaderRoutine *routine,
- void *private_data);
-extern XLogReaderRoutine *LocalXLogReaderRoutine(void);
+ WALSegmentCleanupCB cleanup_cb);
/* Free an XLogReader */
extern void XLogReaderFree(XLogReaderState *state);
@@ -276,12 +253,17 @@ extern void WALOpenSegmentInit(WALOpenSegment *seg, WALSegmentContext *segcxt,
/* Position the XLogReader to given record */
extern void XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr);
#ifdef FRONTEND
-extern XLogRecPtr XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr);
+/* Function type definition for the read_page callback */
+typedef bool (*XLogFindNextRecordCB) (XLogReaderState *xlogreader,
+ void *private);
+extern XLogRecPtr XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr,
+ XLogFindNextRecordCB read_page, void *private);
#endif /* FRONTEND */
/* Read the next XLog record. Returns NULL on end-of-WAL or failure */
-extern struct XLogRecord *XLogReadRecord(XLogReaderState *state,
- char **errormsg);
+extern XLogReadRecordResult XLogReadRecord(XLogReaderState *state,
+ XLogRecord **record,
+ char **errormsg);
/* Validate a page */
extern bool XLogReaderValidatePageHeader(XLogReaderState *state,
@@ -301,6 +283,7 @@ typedef struct WALReadError
} WALReadError;
extern bool WALRead(XLogReaderState *state,
+ WALSegmentOpenCB segopenfn, WALSegmentCloseCB sgclosefn,
char *buf, XLogRecPtr startptr, Size count,
TimeLineID tli, WALReadError *errinfo);
diff --git a/src/include/access/xlogutils.h b/src/include/access/xlogutils.h
index c287edf206..482e4ced69 100644
--- a/src/include/access/xlogutils.h
+++ b/src/include/access/xlogutils.h
@@ -47,9 +47,7 @@ extern Buffer XLogReadBufferExtended(RelFileNode rnode, ForkNumber forknum,
extern Relation CreateFakeRelcacheEntry(RelFileNode rnode);
extern void FreeFakeRelcacheEntry(Relation fakerel);
-extern bool read_local_xlog_page(XLogReaderState *state,
- XLogRecPtr targetPagePtr, int reqLen,
- XLogRecPtr targetRecPtr, char *cur_page);
+extern bool read_local_xlog_page(XLogReaderState *state);
extern void wal_segment_open(XLogReaderState *state,
XLogSegNo nextSegNo,
TimeLineID *tli_p);
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index c2f2475e5d..a743db49cf 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -29,6 +29,10 @@ typedef void (*LogicalOutputPluginWriterUpdateProgress) (struct LogicalDecodingC
TransactionId xid
);
+typedef struct LogicalDecodingContext LogicalDecodingContext;
+
+typedef bool (*LogicalDecodingXLogPageReadCB)(XLogReaderState *ctx);
+
typedef struct LogicalDecodingContext
{
/* memory context this is all allocated in */
@@ -39,6 +43,7 @@ typedef struct LogicalDecodingContext
/* infrastructure pieces for decoding */
XLogReaderState *reader;
+ LogicalDecodingXLogPageReadCB page_read;
struct ReorderBuffer *reorder;
struct SnapBuild *snapshot_builder;
@@ -95,14 +100,16 @@ extern LogicalDecodingContext *CreateInitDecodingContext(char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
XLogRecPtr restart_lsn,
- XLogReaderRoutine *xl_routine,
+ LogicalDecodingXLogPageReadCB page_read,
+ WALSegmentCleanupCB cleanup_cb,
LogicalOutputPluginWriterPrepareWrite prepare_write,
LogicalOutputPluginWriterWrite do_write,
LogicalOutputPluginWriterUpdateProgress update_progress);
extern LogicalDecodingContext *CreateDecodingContext(XLogRecPtr start_lsn,
List *output_plugin_options,
bool fast_forward,
- XLogReaderRoutine *xl_routine,
+ LogicalDecodingXLogPageReadCB page_read,
+ WALSegmentCleanupCB cleanup_cb,
LogicalOutputPluginWriterPrepareWrite prepare_write,
LogicalOutputPluginWriterWrite do_write,
LogicalOutputPluginWriterUpdateProgress update_progress);
--
2.18.2
From 4774cc0cff9e90abda426bdf7e0ef1050e1b81a8 Mon Sep 17 00:00:00 2001
From: Kyotaro Horiguchi <horiguchi.kyotaro@lab.ntt.co.jp>
Date: Tue, 10 Sep 2019 17:28:48 +0900
Subject: [PATCH v10 3/4] Remove globals readOff, readLen and readSegNo
The first two variables are functionally duplicate with them in
XLogReaderState. Remove the globals along with readSegNo, which
behaves in the similar way.
---
src/backend/access/transam/xlog.c | 79 ++++++++++++++-----------------
src/include/access/xlogreader.h | 1 +
2 files changed, 37 insertions(+), 43 deletions(-)
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 840218efee..694307a177 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -801,18 +801,14 @@ static XLogSegNo openLogSegNo = 0;
* These variables are used similarly to the ones above, but for reading
* the XLOG. Note, however, that readOff generally represents the offset
* of the page just read, not the seek position of the FD itself, which
- * will be just past that page. readLen indicates how much of the current
- * page has been read into readBuf, and readSource indicates where we got
- * the currently open file from.
+ * will be just past that page. readSource indicates where we got the
+ * currently open file from.
* Note: we could use Reserve/ReleaseExternalFD to track consumption of
* this FD too; but it doesn't currently seem worthwhile, since the XLOG is
* not read by general-purpose sessions.
*/
static int readFile = -1;
-static XLogSegNo readSegNo = 0;
-static uint32 readOff = 0;
-static uint32 readLen = 0;
-static XLogSource readSource = XLOG_FROM_ANY;
+static XLogSource readSource = 0; /* XLOG_FROM_* code */
/*
* Keeps track of which source we're currently reading from. This is
@@ -902,10 +898,12 @@ static bool InstallXLogFileSegment(XLogSegNo *segno, char *tmppath,
static int XLogFileRead(XLogSegNo segno, int emode, TimeLineID tli,
XLogSource source, bool notfoundOk);
static int XLogFileReadAnyTLI(XLogSegNo segno, int emode, XLogSource source);
-static bool XLogPageRead(XLogReaderState *xlogreader,
+static bool XLogPageRead(XLogReaderState *state,
bool fetching_ckpt, int emode, bool randAccess);
static bool WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
- bool fetching_ckpt, XLogRecPtr tliRecPtr);
+ bool fetching_ckpt,
+ XLogRecPtr tliRecPtr,
+ XLogSegNo readSegNo);
static int emode_for_corrupt_record(int emode, XLogRecPtr RecPtr);
static void XLogFileClose(void);
static void PreallocXlogFiles(XLogRecPtr endptr);
@@ -7662,7 +7660,8 @@ StartupXLOG(void)
XLogRecPtr pageBeginPtr;
pageBeginPtr = EndOfLog - (EndOfLog % XLOG_BLCKSZ);
- Assert(readOff == XLogSegmentOffset(pageBeginPtr, wal_segment_size));
+ Assert(XLogSegmentOffset(xlogreader->readPagePtr, wal_segment_size) ==
+ XLogSegmentOffset(pageBeginPtr, wal_segment_size));
firstIdx = XLogRecPtrToBufIdx(EndOfLog);
@@ -11844,13 +11843,14 @@ CancelBackup(void)
* sleep and retry.
*/
static bool
-XLogPageRead(XLogReaderState *xlogreader,
+XLogPageRead(XLogReaderState *state,
bool fetching_ckpt, int emode, bool randAccess)
{
- char *readBuf = xlogreader->readBuf;
- XLogRecPtr targetPagePtr = xlogreader->readPagePtr;
- int reqLen = xlogreader->readLen;
- XLogRecPtr targetRecPtr = xlogreader->ReadRecPtr;
+ char *readBuf = state->readBuf;
+ XLogRecPtr targetPagePtr = state->readPagePtr;
+ int reqLen = state->readLen;
+ int readLen = 0;
+ XLogRecPtr targetRecPtr = state->ReadRecPtr;
uint32 targetPageOff;
XLogSegNo targetSegNo PG_USED_FOR_ASSERTS_ONLY;
int r;
@@ -11863,7 +11863,7 @@ XLogPageRead(XLogReaderState *xlogreader,
* is not in the currently open one.
*/
if (readFile >= 0 &&
- !XLByteInSeg(targetPagePtr, readSegNo, wal_segment_size))
+ !XLByteInSeg(targetPagePtr, state->readSegNo, wal_segment_size))
{
/*
* Request a restartpoint if we've replayed too much xlog since the
@@ -11871,10 +11871,10 @@ XLogPageRead(XLogReaderState *xlogreader,
*/
if (bgwriterLaunched)
{
- if (XLogCheckpointNeeded(readSegNo))
+ if (XLogCheckpointNeeded(state->readSegNo))
{
(void) GetRedoRecPtr();
- if (XLogCheckpointNeeded(readSegNo))
+ if (XLogCheckpointNeeded(state->readSegNo))
RequestCheckpoint(CHECKPOINT_CAUSE_XLOG);
}
}
@@ -11884,7 +11884,7 @@ XLogPageRead(XLogReaderState *xlogreader,
readSource = XLOG_FROM_ANY;
}
- XLByteToSeg(targetPagePtr, readSegNo, wal_segment_size);
+ XLByteToSeg(targetPagePtr, state->readSegNo, wal_segment_size);
retry:
/* See if we need to retrieve more data */
@@ -11893,17 +11893,14 @@ retry:
flushedUpto < targetPagePtr + reqLen))
{
if (!WaitForWALToBecomeAvailable(targetPagePtr + reqLen,
- randAccess,
- fetching_ckpt,
- targetRecPtr))
+ randAccess, fetching_ckpt,
+ targetRecPtr, state->readSegNo))
{
if (readFile >= 0)
close(readFile);
readFile = -1;
- readLen = 0;
readSource = XLOG_FROM_ANY;
-
- xlogreader->readLen = -1;
+ state->readLen = -1;
return false;
}
}
@@ -11931,40 +11928,36 @@ retry:
else
readLen = XLOG_BLCKSZ;
- /* Read the requested page */
- readOff = targetPageOff;
-
pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
- r = pg_pread(readFile, readBuf, XLOG_BLCKSZ, (off_t) readOff);
+ r = pg_pread(readFile, readBuf, XLOG_BLCKSZ, (off_t) targetPageOff);
if (r != XLOG_BLCKSZ)
{
char fname[MAXFNAMELEN];
int save_errno = errno;
pgstat_report_wait_end();
- XLogFileName(fname, curFileTLI, readSegNo, wal_segment_size);
+ XLogFileName(fname, curFileTLI, state->readSegNo, wal_segment_size);
if (r < 0)
{
errno = save_errno;
ereport(emode_for_corrupt_record(emode, targetPagePtr + reqLen),
(errcode_for_file_access(),
errmsg("could not read from log segment %s, offset %u: %m",
- fname, readOff)));
+ fname, targetPageOff)));
}
else
ereport(emode_for_corrupt_record(emode, targetPagePtr + reqLen),
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("could not read from log segment %s, offset %u: read %d of %zu",
- fname, readOff, r, (Size) XLOG_BLCKSZ)));
+ fname, targetPageOff, r, (Size) XLOG_BLCKSZ)));
goto next_record_is_invalid;
}
pgstat_report_wait_end();
- Assert(targetSegNo == readSegNo);
- Assert(targetPageOff == readOff);
+ Assert(targetSegNo == state->readSegNo);
Assert(reqLen <= readLen);
- xlogreader->seg.ws_tli = curFileTLI;
+ state->seg.ws_tli = curFileTLI;
/*
* Check the page header immediately, so that we can retry immediately if
@@ -11992,15 +11985,15 @@ retry:
* Validating the page header is cheap enough that doing it twice
* shouldn't be a big deal from a performance point of view.
*/
- if (!XLogReaderValidatePageHeader(xlogreader, targetPagePtr, readBuf))
+ if (!XLogReaderValidatePageHeader(state, targetPagePtr, readBuf))
{
- /* reset any error XLogReaderValidatePageHeader() might have set */
- xlogreader->errormsg_buf[0] = '\0';
+ /* reset any error StateValidatePageHeader() might have set */
+ state->errormsg_buf[0] = '\0';
goto next_record_is_invalid;
}
- Assert(xlogreader->readPagePtr == targetPagePtr);
- xlogreader->readLen = readLen;
+ Assert(state->readPagePtr == targetPagePtr);
+ state->readLen = readLen;
return true;
next_record_is_invalid:
@@ -12009,14 +12002,13 @@ next_record_is_invalid:
if (readFile >= 0)
close(readFile);
readFile = -1;
- readLen = 0;
readSource = XLOG_FROM_ANY;
/* In standby-mode, keep trying */
if (StandbyMode)
goto retry;
- xlogreader->readLen = -1;
+ state->readLen = -1;
return false;
}
@@ -12048,7 +12040,8 @@ next_record_is_invalid:
*/
static bool
WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
- bool fetching_ckpt, XLogRecPtr tliRecPtr)
+ bool fetching_ckpt, XLogRecPtr tliRecPtr,
+ XLogSegNo readSegNo)
{
static TimestampTz last_fail_time = 0;
TimestampTz now;
diff --git a/src/include/access/xlogreader.h b/src/include/access/xlogreader.h
index 1d0167e26d..79bb2bc537 100644
--- a/src/include/access/xlogreader.h
+++ b/src/include/access/xlogreader.h
@@ -156,6 +156,7 @@ struct XLogReaderState
* read by reader, which must be larger than
* the request, or -1 on error */
TimeLineID readPageTLI; /* TLI for data currently in readBuf */
+ XLogSegNo readSegNo; /* Segment # for data currently in readBuf */
char *readBuf; /* buffer to store data */
bool page_verified; /* is the page header on the buffer verified? */
bool record_verified;/* is the current record header verified? */
--
2.18.2
From d2f988b454a662c76bb3b681f454d7d35c639a33 Mon Sep 17 00:00:00 2001
From: Kyotaro Horiguchi <horiguchi.kyotaro@lab.ntt.co.jp>
Date: Thu, 5 Sep 2019 21:29:32 +0900
Subject: [PATCH v10 4/4] Change policy of XLog read-buffer allocation
Page buffer in XLogReaderState was allocated by XLogReaderAllcoate but
actually it'd be the responsibility to the callers of XLogReadRecord,
which now actually reads in pages. This patch does that.
---
src/backend/access/transam/twophase.c | 2 ++
src/backend/access/transam/xlog.c | 2 ++
src/backend/access/transam/xlogreader.c | 3 ---
src/backend/replication/logical/logical.c | 2 ++
src/bin/pg_rewind/parsexlog.c | 6 ++++++
src/bin/pg_waldump/pg_waldump.c | 2 ++
6 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index 8630ad2032..7f394156bd 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -1337,6 +1337,7 @@ XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len)
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed while allocating a WAL reading processor.")));
+ xlogreader->readBuf = palloc(XLOG_BLCKSZ);
XLogBeginRead(xlogreader, lsn);
while (XLogReadRecord(xlogreader, &record, &errormsg) ==
@@ -1367,6 +1368,7 @@ XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len)
*buf = palloc(sizeof(char) * XLogRecGetDataLen(xlogreader));
memcpy(*buf, XLogRecGetData(xlogreader), sizeof(char) * XLogRecGetDataLen(xlogreader));
+ pfree(xlogreader->readBuf);
XLogReaderFree(xlogreader);
}
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 694307a177..b144e3e241 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6477,6 +6477,7 @@ StartupXLOG(void)
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed while allocating a WAL reading processor.")));
+ xlogreader->readBuf = palloc(XLOG_BLCKSZ);
xlogreader->system_identifier = ControlFile->system_identifier;
/*
@@ -7889,6 +7890,7 @@ StartupXLOG(void)
close(readFile);
readFile = -1;
}
+ pfree(xlogreader->readBuf);
XLogReaderFree(xlogreader);
/*
diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index bdde75086c..71a4931131 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -110,7 +110,6 @@ XLogReaderAllocate(int wal_segment_size, const char *waldir,
MCXT_ALLOC_NO_OOM);
if (!state->errormsg_buf)
{
- pfree(state->readBuf);
pfree(state);
return NULL;
}
@@ -123,7 +122,6 @@ XLogReaderAllocate(int wal_segment_size, const char *waldir,
if (!allocate_recordbuf(state, 0))
{
pfree(state->errormsg_buf);
- pfree(state->readBuf);
pfree(state);
return NULL;
}
@@ -150,7 +148,6 @@ XLogReaderFree(XLogReaderState *state)
pfree(state->errormsg_buf);
if (state->readRecordBuf)
pfree(state->readRecordBuf);
- pfree(state->readBuf);
pfree(state);
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index d99474c173..18d3248192 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -175,6 +175,7 @@ StartupDecodingContext(List *output_plugin_options,
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
+ ctx->reader->readBuf = palloc(XLOG_BLCKSZ);
ctx->page_read = page_read;
ctx->reorder = ReorderBufferAllocate();
@@ -525,6 +526,7 @@ FreeDecodingContext(LogicalDecodingContext *ctx)
ReorderBufferFree(ctx->reorder);
FreeSnapshotBuilder(ctx->snapshot_builder);
+ pfree(ctx->reader->readBuf);
XLogReaderFree(ctx->reader);
MemoryContextDelete(ctx->context);
}
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index cad8e13965..c6247344d6 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -61,6 +61,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
if (xlogreader == NULL)
pg_fatal("out of memory");
+ xlogreader->readBuf = pg_malloc(XLOG_BLCKSZ);
XLogBeginRead(xlogreader, startpoint);
do
@@ -90,6 +91,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
} while (xlogreader->ReadRecPtr != endpoint);
+ pg_free(xlogreader->readBuf);
XLogReaderFree(xlogreader);
if (xlogreadfd != -1)
{
@@ -114,6 +116,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex,
xlogreader = XLogReaderAllocate(WalSegSz, datadir, NULL);
if (xlogreader == NULL)
pg_fatal("out of memory");
+ xlogreader->readBuf = pg_malloc(XLOG_BLCKSZ);
XLogBeginRead(xlogreader, ptr);
while (XLogReadRecord(xlogreader, &record, &errormsg) ==
@@ -133,6 +136,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex,
}
endptr = xlogreader->EndRecPtr;
+ pg_free(xlogreader->readBuf);
XLogReaderFree(xlogreader);
if (xlogreadfd != -1)
{
@@ -174,6 +178,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
xlogreader = XLogReaderAllocate(WalSegSz, datadir, NULL);
if (xlogreader == NULL)
pg_fatal("out of memory");
+ xlogreader->readBuf = pg_malloc(XLOG_BLCKSZ);
searchptr = forkptr;
for (;;)
@@ -224,6 +229,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
searchptr = record->xl_prev;
}
+ pg_free(xlogreader->readBuf);
XLogReaderFree(xlogreader);
if (xlogreadfd != -1)
{
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index 02e71138cc..14f2eb1d28 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -1052,6 +1052,7 @@ main(int argc, char **argv)
if (!xlogreader_state)
fatal_error("out of memory");
+ xlogreader_state->readBuf = palloc(XLOG_BLCKSZ);
/* first find a valid recptr to start from */
first_record = XLogFindNextRecord(xlogreader_state, private.startptr,
@@ -1131,6 +1132,7 @@ main(int argc, char **argv)
(uint32) xlogreader_state->ReadRecPtr,
errormsg);
+ pfree(xlogreader_state->readBuf);
XLogReaderFree(xlogreader_state);
return EXIT_SUCCESS;
--
2.18.2
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