Re: Remove page-read callback from XLogReaderState.
| От | Kyotaro Horiguchi |
|---|---|
| Тема | Re: Remove page-read callback from XLogReaderState. |
| Дата | |
| Msg-id | 20190910.174054.16391566.horikyota.ntt@gmail.com обсуждение исходный текст |
| Ответ на | Re: Remove page-read callback from XLogReaderState. (Kyotaro Horiguchi <horikyota.ntt@gmail.com>) |
| Ответы |
Re: Remove page-read callback from XLogReaderState.
(Kyotaro Horiguchi <horikyota.ntt@gmail.com>)
|
| Список | pgsql-hackers |
Attached is new version:
- Rebased. Cleaned up
- Rebased to the current master
- Fixed a known bug in the first step patch. It caused
timeline-following failure on a standby of a promoted primary.
- Fixed confused naming and setting of the parameter
includes_paeg_header.
- Removed useless XLogNeedData call in
XLREAD_NEED_CONTINUATION. The first call to the function
ensures that all required data is loaded. Finally, every case
block has just one XLogNeedData call.
- Removed the label "again" in XLogReadRecord. It is now needed
only to repeat XLREAD_NEED_CONTINUATION state. It is naturally
writtable as a while loop.
- Ensure record == NULL when XLogReadRecord returns other than
XLREAD_SUCCESS. Previously the value was not changed in that
case and it was not intuitive behavior for callers.
- Renamed XLREAD_NEED_* to XLREAD_*.
- Removed global variables readOff, readLen, readSegNo. (0003)
Other similar variables like readFile/readSource are left alone
as they are not common states of page reader and not in
XLogReaderState.
The attched are the current status, it is separated to two
significant parts plus one for readability.
v6-0001-Move-callback-call-from-ReadPageInternal-to-XLogR.patch:
ReadPageInternal part of the patch. Moves callback calls from
ReadPageInternal up to XLogReadRecord. Rerorded commit message
and fixed the bug in v5.
v6-0002-Move-page-reader-out-of-XLogReadRecord.patch
The remaining part of the main work. Eliminates callback calls
from XLogReadRecord. Reworded commit message and fixed several
bugs.
v6-0003-Remove-globals-readSegNo-readOff-readLen.patch
Seprate patch to remove some globals that are duplicate with
members of XLogReaderState.
v6-0004-Change-policy-of-XLog-read-buffer-allocation.patch
Separate patch to move page buffer allocation from
XLogReaderAllocation from allers of XLogReadRecord.
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center
From 81d3e58a1f017f34bb654cc4f66a4b9646469349 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 v6 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 | 336 +++++++++++++++----------
src/backend/access/transam/xlogutils.c | 10 +-
src/backend/replication/logical/logicalfuncs.c | 4 +-
src/backend/replication/walsender.c | 10 +-
src/bin/pg_rewind/parsexlog.c | 17 +-
src/bin/pg_waldump/pg_waldump.c | 8 +-
src/include/access/xlogreader.h | 26 +-
src/include/access/xlogutils.h | 2 +-
src/include/replication/logicalfuncs.h | 2 +-
10 files changed, 265 insertions(+), 166 deletions(-)
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 6876537b62..d7f899e738 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -884,7 +884,7 @@ static bool InstallXLogFileSegment(XLogSegNo *segno, char *tmppath,
static int XLogFileRead(XLogSegNo segno, int emode, TimeLineID tli,
int source, bool notfoundOk);
static int XLogFileReadAnyTLI(XLogSegNo segno, int emode, int source);
-static int XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
+static bool XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
TimeLineID *readTLI);
static bool WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
@@ -4249,7 +4249,6 @@ ReadRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr, 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 = (RecPtr != InvalidXLogRecPtr);
@@ -11521,7 +11520,7 @@ 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, TimeLineID *readTLI)
{
@@ -11580,7 +11579,8 @@ retry:
readLen = 0;
readSource = 0;
- return -1;
+ xlogreader->readLen = -1;
+ return false;
}
}
@@ -11675,7 +11675,8 @@ retry:
goto next_record_is_invalid;
}
- return readLen;
+ xlogreader->readLen = readLen;
+ return true;
next_record_is_invalid:
lastSourceFailed = true;
@@ -11689,8 +11690,9 @@ 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 a66e3324b1..12a52159a9 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -34,9 +34,9 @@
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 void XLogReaderInvalReadState(XLogReaderState *state);
+static bool XLogNeedData(XLogReaderState *state, XLogRecPtr pageptr,
+ int reqLen, bool header_inclusive);
+static void XLogReaderDiscardReadingPage(XLogReaderState *state);
static bool ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess);
static bool ValidXLogRecord(XLogReaderState *state, XLogRecord *record,
@@ -101,7 +101,7 @@ XLogReaderAllocate(int wal_segment_size, XLogPageReadCB pagereadfunc,
/* system_identifier initialized to zeroes above */
state->private_data = private_data;
/* ReadRecPtr and EndRecPtr initialized to zeroes above */
- /* readSegNo, readOff, readLen, readPageTLI initialized to zeroes above */
+ /* readSegNo, readLen, readPageTLI initialized to zeroes above */
state->errormsg_buf = palloc_extended(MAX_ERRORMSG_LEN + 1,
MCXT_ALLOC_NO_OOM);
if (!state->errormsg_buf)
@@ -225,7 +225,6 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg)
uint32 targetRecOff;
uint32 pageHeaderSize;
bool gotheader;
- int readOff;
/*
* randAccess indicates whether to verify the previous-record pointer of
@@ -277,15 +276,21 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, 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->read_page(state, state->readPagePtr, state->readLen,
+ RecPtr, state->readBuf,
+ &state->readPageTLI))
+ break;
+ }
+
+ if (!state->page_verified)
goto err;
/*
- * ReadPageInternal always returns at least the page header, so we can
- * examine it now.
+ * We have loaded at least the page header, so we can examine it now.
*/
pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
if (targetRecOff == 0)
@@ -311,8 +316,8 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, 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.
@@ -385,18 +390,26 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, 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->read_page(state, state->readPagePtr, state->readLen,
+ state->ReadRecPtr, state->readBuf,
+ &state->readPageTLI))
+ 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;
@@ -425,21 +438,14 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, 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;
@@ -469,9 +475,16 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, 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->read_page(state, state->readPagePtr, state->readLen,
+ state->ReadRecPtr, state->readBuf,
+ &state->readPageTLI))
+ break;
+ }
+
+ if (!state->page_verified)
goto err;
/* Record does not cross a page boundary */
@@ -505,7 +518,7 @@ err:
* Invalidate the read state. We might read from a different source after
* failure.
*/
- XLogReaderInvalReadState(state);
+ XLogReaderDiscardReadingPage(state);
if (state->errormsg_buf[0] != '\0')
*errormsg = state->errormsg_buf;
@@ -514,120 +527,183 @@ err:
}
/*
- * Read a single xlog page including at least [pageptr, reqLen] of valid data
- * via the read_page() 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 read_page 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;
-
- Assert((pageptr % XLOG_BLCKSZ) == 0);
-
- XLByteToSeg(pageptr, targetSegNo, state->wal_segment_size);
- targetPageOff = XLogSegmentOffset(pageptr, state->wal_segment_size);
+ uint32 addLen = 0;
/* check whether we have all the requested data already */
- if (targetSegNo == state->readSegNo && targetPageOff == state->readOff &&
- reqLen <= state->readLen)
- return state->readLen;
+ if (state->page_verified && pageptr == state->readPagePtr)
+ {
+ if (!header_inclusive)
+ {
+ /*
+ * calculate additional length for page header so that the total
+ * length doesn't exceed the block size.
+ */
+ uint32 pageHeaderSize =
+ XLogPageHeaderSize((XLogPageHeader) state->readBuf);
+
+ addLen = pageHeaderSize;
+ if (reqLen + pageHeaderSize <= XLOG_BLCKSZ)
+ addLen = pageHeaderSize;
+ else
+ addLen = XLOG_BLCKSZ - reqLen;
+ }
+
+ if (reqLen + addLen <= state->readLen)
+ return false;
+ }
+
+ /* Haven't loaded any data yet? Then request it. */
+ if (XLogRecPtrIsInvalid(state->readPagePtr) ||
+ state->readPagePtr != pageptr || state->readLen < 0)
+ {
+ state->readPagePtr = pageptr;
+ state->readLen = Max(reqLen, SizeOfXLogShortPHD);
+ state->page_verified = false;
+ return true;
+ }
+
+ if (!state->page_verified)
+ {
+ uint32 pageHeaderSize;
+ uint32 addLen = 0;
+
+ /* 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 if it is a long header if any.
+ */
+ pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
+
+ /*
+ * If we have not loaded a page so far, readLen is zero, which is
+ * shorter than pageHeaderSize here.
+ */
+ if (state->readLen < pageHeaderSize)
+ {
+ state->readPagePtr = pageptr;
+ state->readLen = pageHeaderSize;
+ return true;
+ }
+
+ /*
+ * Now that we know we have the full header, validate it.
+ */
+ if (!XLogReaderValidatePageHeader(state, state->readPagePtr,
+ (char *) state->readBuf))
+ {
+ /* force reading the page again. */
+ XLogReaderDiscardReadingPage(state);
+
+ return false;
+ }
+
+ state->page_verified = true;
+
+ XLByteToSeg(state->readPagePtr, state->readSegNo,
+ state->wal_segment_size);
+
+ /*
+ * calculate additional length for page header so that the total
+ * length doesn't exceed the block size.
+ */
+ if (!header_inclusive)
+ {
+ addLen = pageHeaderSize;
+ if (reqLen + pageHeaderSize <= XLOG_BLCKSZ)
+ addLen = pageHeaderSize;
+ else
+ addLen = XLOG_BLCKSZ - reqLen;
+
+ Assert(addLen >= 0);
+ }
+
+ /* Usually we have requested data loaded in buffer here. */
+ if (pageptr == state->readPagePtr && reqLen + addLen <= state->readLen)
+ return false;
+
+ /*
+ * In the case the page is requested for the first record in the page,
+ * the previous request have been made not counting page header
+ * length. Request again for the same page with the length known to be
+ * needed. Otherwise we don't know the header length of the new page.
+ */
+ if (pageptr != state->readPagePtr)
+ addLen = 0;
+ }
+
+ /* Data is not in our buffer, make a new load request to the caller. */
+ XLByteToSeg(pageptr, targetSegNo, state->wal_segment_size);
+ targetPageOff = XLogSegmentOffset(pageptr, state->wal_segment_size);
+ Assert((pageptr % XLOG_BLCKSZ) == 0);
+
+ /*
+ * 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 page, even if we looked at parts of it
- * before, we need to do verification as the read_page 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->readSegNo && targetPageOff != 0)
{
- XLogRecPtr targetSegmentPtr = pageptr - targetPageOff;
-
- readLen = state->read_page(state, targetSegmentPtr, XLOG_BLCKSZ,
- state->currRecPtr,
- state->readBuf, &state->readPageTLI);
- 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 readSegNo, 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 requested page. We need at least a short
+ * page header so that we can validate it.
*/
- readLen = state->read_page(state, pageptr, Max(reqLen, SizeOfXLogShortPHD),
- state->currRecPtr,
- state->readBuf, &state->readPageTLI);
- 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->read_page(state, pageptr, XLogPageHeaderSize(hdr),
- state->currRecPtr,
- state->readBuf, &state->readPageTLI);
- 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->readSegNo = targetSegNo;
- state->readOff = targetPageOff;
- state->readLen = readLen;
-
- return readLen;
-
-err:
- XLogReaderInvalReadState(state);
- return -1;
+ state->readPagePtr = pageptr;
+ state->readLen = Max(reqLen + addLen, SizeOfXLogShortPHD);
+ return true;
}
/*
- * Invalidate the xlogreader's read state to force a re-read.
+ * Invalidate current reading page buffer
*/
static void
-XLogReaderInvalReadState(XLogReaderState *state)
+XLogReaderDiscardReadingPage(XLogReaderState *state)
{
- state->readSegNo = 0;
- state->readOff = 0;
- state->readLen = 0;
+ state->readPagePtr = InvalidXLogRecPtr;
}
/*
@@ -905,7 +981,6 @@ XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
XLogRecPtr targetPagePtr;
int targetRecOff;
uint32 pageHeaderSize;
- int readLen;
/*
* Compute targetRecOff. It should typically be equal or greater than
@@ -913,7 +988,7 @@ 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
+ * CheckPage() is prepared to handle that and will read at
* least short page-header worth of data
*/
targetRecOff = tmpRecPtr % XLOG_BLCKSZ;
@@ -921,19 +996,24 @@ 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->read_page(state, state->readPagePtr, state->readLen,
+ state->ReadRecPtr, state->readBuf,
+ &state->readPageTLI))
+ 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)
@@ -990,7 +1070,7 @@ out:
/* Reset state to what we had before finding the record */
state->ReadRecPtr = saved_state.ReadRecPtr;
state->EndRecPtr = saved_state.EndRecPtr;
- XLogReaderInvalReadState(state);
+ XLogReaderDiscardReadingPage(state);
return found;
}
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 1fc39333f1..dad9074b9f 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -803,7 +803,7 @@ void
XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wantLength)
{
const XLogRecPtr lastReadPage = state->readSegNo *
- state->wal_segment_size + state->readOff;
+ state->wal_segment_size + state->readLen;
Assert(wantPage != InvalidXLogRecPtr && wantPage % XLOG_BLCKSZ == 0);
Assert(wantLength <= XLOG_BLCKSZ);
@@ -907,7 +907,7 @@ XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wa
* 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,
TimeLineID *pageTLI)
@@ -1009,7 +1009,8 @@ 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
{
@@ -1026,5 +1027,6 @@ read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr,
XLOG_BLCKSZ);
/* number of valid bytes in the buffer */
- return count;
+ state->readLen = count;
+ return true;
}
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index d974400d6e..7210a940bd 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -114,12 +114,12 @@ check_permissions(void)
(errmsg("must be superuser or replication role to use replication slots"))));
}
-int
+bool
logical_read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr,
int reqLen, XLogRecPtr targetRecPtr, char *cur_page, TimeLineID *pageTLI)
{
return read_local_xlog_page(state, targetPagePtr, reqLen,
- targetRecPtr, cur_page, pageTLI);
+ targetRecPtr, cur_page, pageTLI);
}
/*
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 23870a25a5..cc35e2a04d 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -761,7 +761,7 @@ 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, TimeLineID *pageTLI)
{
@@ -779,7 +779,10 @@ 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 */
@@ -789,7 +792,8 @@ logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int req
/* now actually read the data, we know it's there */
XLogRead(cur_page, targetPagePtr, XLOG_BLCKSZ);
- return count;
+ state->readLen = count;
+ return true;
}
/*
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 63c3879ead..4df53964e4 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -47,7 +47,7 @@ typedef struct XLogPageReadPrivate
int tliIndex;
} XLogPageReadPrivate;
-static int SimpleXLogPageRead(XLogReaderState *xlogreader,
+static bool SimpleXLogPageRead(XLogReaderState *xlogreader,
XLogRecPtr targetPagePtr,
int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
TimeLineID *pageTLI);
@@ -235,7 +235,7 @@ 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,
TimeLineID *pageTLI)
@@ -290,7 +290,8 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
if (xlogreadfd < 0)
{
pg_log_error("could not open file \"%s\": %m", xlogfpath);
- return -1;
+ xlogreader->readLen = -1;
+ return false;
}
}
@@ -303,7 +304,8 @@ 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;
}
@@ -316,13 +318,16 @@ 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);
*pageTLI = 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 b95d467805..96d1f36ebc 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -421,7 +421,7 @@ XLogDumpXLogRead(const char *directory, TimeLineID timeline_id,
/*
* XLogReader read_page callback
*/
-static int
+static bool
XLogDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
XLogRecPtr targetPtr, char *readBuff, TimeLineID *curFileTLI)
{
@@ -437,14 +437,16 @@ XLogDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
else
{
private->endptr_reached = true;
- return -1;
+ state->readLen = -1;
+ return false;
}
}
XLogDumpXLogRead(private->inpath, private->timeline, targetPagePtr,
readBuff, count);
- return count;
+ state->readLen = count;
+ return true;
}
/*
diff --git a/src/include/access/xlogreader.h b/src/include/access/xlogreader.h
index 735b1bd2fd..6de7c19a2a 100644
--- a/src/include/access/xlogreader.h
+++ b/src/include/access/xlogreader.h
@@ -34,7 +34,7 @@
typedef struct XLogReaderState XLogReaderState;
/* Function type definition for the read_page callback */
-typedef int (*XLogPageReadCB) (XLogReaderState *xlogreader,
+typedef bool (*XLogPageReadCB) (XLogReaderState *xlogreader,
XLogRecPtr targetPagePtr,
int reqLen,
XLogRecPtr targetRecPtr,
@@ -123,6 +123,18 @@ 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 */
/* ----------------------------------------
* Decoded representation of current record
@@ -149,17 +161,9 @@ struct XLogReaderState
* ----------------------------------------
*/
- /*
- * Buffer for currently read page (XLOG_BLCKSZ bytes, valid up to at least
- * readLen bytes)
- */
- char *readBuf;
- uint32 readLen;
-
- /* last read segment, segment offset, TLI for data currently in readBuf */
+ /* last read segment and segment offset for data currently in readBuf */
+ bool page_verified;
XLogSegNo readSegNo;
- uint32 readOff;
- TimeLineID readPageTLI;
/*
* beginning of prior page read, and its TLI. Doesn't necessarily
diff --git a/src/include/access/xlogutils.h b/src/include/access/xlogutils.h
index 4105b59904..0842af9f95 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,
TimeLineID *pageTLI);
diff --git a/src/include/replication/logicalfuncs.h b/src/include/replication/logicalfuncs.h
index a9c178a9e6..8e52b1f4aa 100644
--- a/src/include/replication/logicalfuncs.h
+++ b/src/include/replication/logicalfuncs.h
@@ -11,7 +11,7 @@
#include "replication/logical.h"
-extern int logical_read_local_xlog_page(XLogReaderState *state,
+extern bool logical_read_local_xlog_page(XLogReaderState *state,
XLogRecPtr targetPagePtr,
int reqLen, XLogRecPtr targetRecPtr,
char *cur_page, TimeLineID *pageTLI);
--
2.16.3
From 1998e14fbad74aa2deb4c4bead40dd019b5a6706 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 v6 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 | 11 +-
src/backend/access/transam/xlog.c | 50 +-
src/backend/access/transam/xlogreader.c | 708 +++++++++++++++----------
src/backend/access/transam/xlogutils.c | 14 +-
src/backend/replication/logical/logical.c | 17 +-
src/backend/replication/logical/logicalfuncs.c | 14 +-
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 14 +-
src/bin/pg_rewind/parsexlog.c | 83 ++-
src/bin/pg_waldump/pg_waldump.c | 24 +-
src/include/access/xlogreader.h | 90 ++--
src/include/access/xlogutils.h | 5 +-
src/include/replication/logical.h | 9 +-
src/include/replication/logicalfuncs.h | 5 +-
14 files changed, 617 insertions(+), 435 deletions(-)
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index 477709bbc2..a736504d62 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -1386,15 +1386,20 @@ XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len)
XLogReaderState *xlogreader;
char *errormsg;
- xlogreader = XLogReaderAllocate(wal_segment_size, &read_local_xlog_page,
- NULL);
+ xlogreader = XLogReaderAllocate(wal_segment_size);
if (!xlogreader)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed while allocating a WAL reading processor.")));
- record = XLogReadRecord(xlogreader, lsn, &errormsg);
+ while (XLogReadRecord(xlogreader, lsn, &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 d7f899e738..34ab4ea359 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -803,13 +803,6 @@ static XLogSource readSource = 0; /* XLOG_FROM_* code */
static XLogSource currentSource = 0; /* XLOG_FROM_* code */
static bool lastSourceFailed = 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
@@ -884,9 +877,8 @@ static bool InstallXLogFileSegment(XLogSegNo *segno, char *tmppath,
static int XLogFileRead(XLogSegNo segno, int emode, TimeLineID tli,
int source, bool notfoundOk);
static int XLogFileReadAnyTLI(XLogSegNo segno, int emode, int source);
-static bool XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
- int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
- TimeLineID *readTLI);
+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);
@@ -1195,7 +1187,7 @@ XLogInsertRecord(XLogRecData *rdata,
appendBinaryStringInfo(&recordBuf, rdata->data, rdata->len);
if (!debug_reader)
- debug_reader = XLogReaderAllocate(wal_segment_size, NULL, NULL);
+ debug_reader = XLogReaderAllocate(wal_segment_size);
if (!debug_reader)
{
@@ -4247,11 +4239,7 @@ ReadRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr, int emode,
bool fetching_ckpt)
{
XLogRecord *record;
- XLogPageReadPrivate *private = (XLogPageReadPrivate *) xlogreader->private_data;
-
- private->fetching_ckpt = fetching_ckpt;
- private->emode = emode;
- private->randAccess = (RecPtr != InvalidXLogRecPtr);
+ bool randAccess = (RecPtr != InvalidXLogRecPtr);
/* This is the first attempt to read this page. */
lastSourceFailed = false;
@@ -4259,8 +4247,15 @@ ReadRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr, int emode,
for (;;)
{
char *errormsg;
+ XLogReadRecordResult result;
+
+ while ((result = XLogReadRecord(xlogreader, RecPtr, &record, &errormsg))
+ == XLREAD_NEED_DATA)
+ {
+ if (!XLogPageRead(xlogreader, fetching_ckpt, emode, randAccess))
+ break;
+ }
- record = XLogReadRecord(xlogreader, RecPtr, &errormsg);
ReadRecPtr = xlogreader->ReadRecPtr;
EndRecPtr = xlogreader->EndRecPtr;
if (record == NULL)
@@ -6210,7 +6205,6 @@ StartupXLOG(void)
bool backupFromStandby = false;
DBState dbstate_at_startup;
XLogReaderState *xlogreader;
- XLogPageReadPrivate private;
bool fast_promoted = false;
struct stat st;
@@ -6351,8 +6345,7 @@ StartupXLOG(void)
OwnLatch(&XLogCtl->recoveryWakeupLatch);
/* Set up XLOG reader facility */
- MemSet(&private, 0, sizeof(XLogPageReadPrivate));
- xlogreader = XLogReaderAllocate(wal_segment_size, &XLogPageRead, &private);
+ xlogreader = XLogReaderAllocate(wal_segment_size);
if (!xlogreader)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
@@ -11521,12 +11514,14 @@ CancelBackup(void)
* sleep and retry.
*/
static bool
-XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr, int reqLen,
- XLogRecPtr targetRecPtr, char *readBuf, TimeLineID *readTLI)
+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;
+ TimeLineID *readTLI = &xlogreader->readPageTLI;
uint32 targetPageOff;
XLogSegNo targetSegNo PG_USED_FOR_ASSERTS_ONLY;
int r;
@@ -11569,8 +11564,8 @@ retry:
receivedUpto < targetPagePtr + reqLen))
{
if (!WaitForWALToBecomeAvailable(targetPagePtr + reqLen,
- private->randAccess,
- private->fetching_ckpt,
+ randAccess,
+ fetching_ckpt,
targetRecPtr))
{
if (readFile >= 0)
@@ -11675,6 +11670,7 @@ 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 12a52159a9..e00fa270ae 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -38,7 +38,7 @@ static bool XLogNeedData(XLogReaderState *state, XLogRecPtr pageptr,
int reqLen, bool header_inclusive);
static void XLogReaderDiscardReadingPage(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);
@@ -68,8 +68,7 @@ report_invalid_record(XLogReaderState *state, const char *fmt,...)
* Returns NULL if the xlogreader couldn't be allocated.
*/
XLogReaderState *
-XLogReaderAllocate(int wal_segment_size, XLogPageReadCB pagereadfunc,
- void *private_data)
+XLogReaderAllocate(int wal_segment_size)
{
XLogReaderState *state;
@@ -97,11 +96,6 @@ XLogReaderAllocate(int wal_segment_size, XLogPageReadCB pagereadfunc,
}
state->wal_segment_size = wal_segment_size;
- state->read_page = pagereadfunc;
- /* system_identifier initialized to zeroes above */
- state->private_data = private_data;
- /* ReadRecPtr and EndRecPtr initialized to zeroes above */
- /* readSegNo, readLen, readPageTLI initialized to zeroes above */
state->errormsg_buf = palloc_extended(MAX_ERRORMSG_LEN + 1,
MCXT_ALLOC_NO_OOM);
if (!state->errormsg_buf)
@@ -201,321 +195,464 @@ allocate_recordbuf(XLogReaderState *state, uint32 reclength)
/*
* Attempt to read an XLOG record.
*
- * If RecPtr is valid, try to read a record at that position. Otherwise
- * try to read a record just after the last one previously read.
+ * When starting to read a new record, valid RecPtr starts reading the record
+ * at that position. If invalid RecPtr is given try to start reading a record
+ * just after the last one previously read. Anytime (means in any internal
+ * state) when valid new RecPtr is given, starts reading the record at that
+ * position. 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 read_page callback fails to read the requested data, NULL is
- * returned. The callback is expected to have reported the error; errormsg
- * is set to NULL.
+ * When a record is successfully read, returns XLREAD_SUCCESS with result
+ * record being stored in *record. Otherwise *record is NULL.
*
- * If the reading fails for some other reason, NULL is also returned, and
- * *errormsg is set to a string with details of the failure.
+ * 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.
*
- * The returned pointer (or *errormsg) points to an internal buffer that's
- * valid until the next call to XLogReadRecord.
- */
-XLogRecord *
-XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg)
-{
- XLogRecord *record;
- XLogRecPtr targetPagePtr;
- bool randAccess;
- uint32 len,
- total_len;
- uint32 targetRecOff;
- uint32 pageHeaderSize;
- bool gotheader;
+ * 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.
- /*
- * 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;
+ * 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.
+ */
+XLogReadRecordResult
+XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, XLogRecord **record,
+ char **errormsg)
+{
+ XLogRecord *prec;
+
+ *record = NULL;
/* reset error state */
*errormsg = NULL;
state->errormsg_buf[0] = '\0';
- ResetDecoder(state);
-
- if (RecPtr == InvalidXLogRecPtr)
- {
- /* No explicit start point; read the record after the one we just read */
- RecPtr = state->EndRecPtr;
-
- if (state->ReadRecPtr == InvalidXLogRecPtr)
- randAccess = true;
-
- /*
- * RecPtr 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, the passed-in record pointer 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.
+ * Reset to the initial state anytime the caller requested new record.
*/
- while (XLogNeedData(state, targetPagePtr,
- Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ),
- targetRecOff != 0))
+ if (RecPtr != InvalidXLogRecPtr && RecPtr != state->ReadRecPtr)
+ state->readRecordState = XLREAD_NEXT_RECORD;
+
+ switch (state->readRecordState)
{
- if (!state->read_page(state, state->readPagePtr, state->readLen,
- RecPtr, state->readBuf,
- &state->readPageTLI))
- break;
- }
+ case XLREAD_NEXT_RECORD:
+ ResetDecoder(state);
- if (!state->page_verified)
- goto err;
-
- /*
- * We have loaded 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)
- {
- /* 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;
- }
-
- /* 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 (RecPtr != InvalidXLogRecPtr)
{
- if (!state->read_page(state, state->readPagePtr, state->readLen,
- state->ReadRecPtr, state->readBuf,
- &state->readPageTLI))
- break;
+ /*
+ * Caller supplied a position to start at.
+ *
+ * In this case, the passed-in record pointer should already be
+ * pointing to a valid record starting position.
+ */
+ state->ReadRecPtr = RecPtr;
+
+ /*
+ * We cannot verify the previous-record pointer when we're
+ * seeking to a particular record. Reset ReadRecPtr so that we
+ * won't try doing that.
+ */
+ state->PrevRecPtr = InvalidXLogRecPtr;
+ state->EndRecPtr = InvalidXLogRecPtr; /* to be tidy */
+ }
+ else
+ {
+ /*
+ * Otherwise, read the record after the one we just read. (Or
+ * the first record, if this is the first call. In that case,
+ * EndRecPtr was set to the desired starting point above.)
+ *
+ * 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 on the next
+ * page, 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;
}
+ 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);
-
- /* Check that the continuation on next page looks valid */
- pageHeader = (XLogPageHeader) state->readBuf;
- if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD))
+ /* examine page header now. */
+ pageHeaderSize =
+ XLogPageHeaderSize((XLogPageHeader) state->readBuf);
+ if (targetRecOff == 0)
{
- report_invalid_record(state,
- "there is no contrecord flag at %X/%X",
- (uint32) (RecPtr >> 32), (uint32) RecPtr);
+ /* 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;
}
+ pageHeader = (XLogPageHeader) state->readBuf;
+ if ((pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
+ targetRecOff == pageHeaderSize)
+ {
+ report_invalid_record(state, "contrecord is requested by %X/%X",
+ (uint32) (state->ReadRecPtr >> 32),
+ (uint32) state->ReadRecPtr);
+ 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.
+ */
+ prec = (XLogRecord *) (state->readBuf +
+ state->ReadRecPtr % XLOG_BLCKSZ);
+ total_len = prec->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 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;
+
+ state->record_verified = 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) (state->ReadRecPtr >> 32),
+ (uint32) state->ReadRecPtr,
+ (uint32) SizeOfXLogRecord, total_len);
+ goto err;
+ }
+ }
+
/*
- * Cross-check that xlp_rem_len agrees with how much of the record
- * we expect there to be left.
+ * 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.
*/
- if (pageHeader->xlp_rem_len == 0 ||
- total_len != (pageHeader->xlp_rem_len + gotlen))
+ state->recordGotLen = 0;
+ state->recordRemainLen = total_len;
+ state->readRecordState = XLREAD_FIRST_FRAGMENT;
+ }
+ /* fall through */
+
+ case XLREAD_FIRST_FRAGMENT:
+ {
+ 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,
- "invalid contrecord length %u at %X/%X",
- pageHeader->xlp_rem_len,
- (uint32) (RecPtr >> 32), (uint32) RecPtr);
+ "record length %u at %X/%X too long",
+ total_len,
+ (uint32) (state->ReadRecPtr >> 32),
+ (uint32) state->ReadRecPtr);
goto err;
}
- /* Append the continuation from this page to the buffer */
- pageHeaderSize = XLogPageHeaderSize(pageHeader);
+ /* 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;
- Assert (pageHeaderSize <= state->readLen);
+ /* Calculate pointer to beginning of next page */
+ state->recordContRecPtr = state->ReadRecPtr + record_len;
+ Assert(state->recordContRecPtr % XLOG_BLCKSZ == 0);
- contdata = (char *) state->readBuf + pageHeaderSize;
- len = XLOG_BLCKSZ - pageHeaderSize;
- if (pageHeader->xlp_rem_len < len)
- len = pageHeader->xlp_rem_len;
-
- Assert (pageHeaderSize + len <= state->readLen);
- memcpy(buffer, (char *) contdata, len);
- buffer += len;
- gotlen += len;
-
- /* If we just reassembled the record header, validate it. */
- if (!gotheader)
- {
- record = (XLogRecord *) state->readRecordBuf;
- if (!ValidXLogRecordHeader(state, RecPtr, state->ReadRecPtr,
- record, randAccess))
- goto err;
- gotheader = true;
- }
- } while (gotlen < total_len);
-
- Assert(gotheader);
-
- record = (XLogRecord *) state->readRecordBuf;
- if (!ValidXLogRecord(state, record, RecPtr))
- goto err;
-
- pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
- state->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))
- {
- if (!state->read_page(state, state->readPagePtr, state->readLen,
- state->ReadRecPtr, state->readBuf,
- &state->readPageTLI))
- break;
+ state->readRecordState = XLREAD_CONTINUATION;
}
+ /* fall through */
- if (!state->page_verified)
- goto err;
+ case XLREAD_CONTINUATION:
+ {
+ XLogPageHeader pageHeader;
+ uint32 pageHeaderSize;
+ XLogRecPtr targetPagePtr;
- /* Record does not cross a page boundary */
- if (!ValidXLogRecord(state, record, RecPtr))
- goto err;
+ /* we enter this state only if we haven't read the whole record. */
+ Assert (state->recordRemainLen > 0);
- state->EndRecPtr = RecPtr + MAXALIGN(total_len);
+ while(state->recordRemainLen > 0)
+ {
+ char *contdata;
+ uint32 request_len;
+ uint32 record_len;
- state->ReadRecPtr = RecPtr;
+ /* 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);
+
+ /* 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;
+ }
+
+ /*
+ * 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;
+ }
+
+ /* Append the continuation from this page to the buffer */
+ pageHeaderSize = XLogPageHeaderSize(pageHeader);
+
+ /*
+ * 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->wal_segment_size - 1;
state->EndRecPtr -= XLogSegmentOffset(state->EndRecPtr, state->wal_segment_size);
}
- 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.
*/
XLogReaderDiscardReadingPage(state);
@@ -523,7 +660,8 @@ err:
if (state->errormsg_buf[0] != '\0')
*errormsg = state->errormsg_buf;
- return NULL;
+ *record = NULL;
+ return XLREAD_FAIL;
}
/*
@@ -711,11 +849,12 @@ XLogReaderDiscardReadingPage(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)
{
@@ -733,7 +872,7 @@ 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
@@ -961,12 +1100,15 @@ XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr,
* debugging purposes.
*/
XLogRecPtr
-XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
+XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr,
+ XLogFindNextRecordCB read_page, void *private)
{
XLogReaderState saved_state = *state;
XLogRecPtr tmpRecPtr;
XLogRecPtr found = InvalidXLogRecPtr;
XLogPageHeader header;
+ XLogRecord *record;
+ XLogReadRecordResult result;
char *errormsg;
Assert(!XLogRecPtrIsInvalid(RecPtr));
@@ -999,9 +1141,7 @@ XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
while(XLogNeedData(state, targetPagePtr, targetRecOff,
targetRecOff != 0))
{
- if (!state->read_page(state, state->readPagePtr, state->readLen,
- state->ReadRecPtr, state->readBuf,
- &state->readPageTLI))
+ if (!read_page(state, private))
break;
}
@@ -1052,11 +1192,19 @@ XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
* because either we're at the first record after the beginning of a page
* or we just jumped over the remaining data of a continuation.
*/
- while (XLogReadRecord(state, tmpRecPtr, &errormsg) != NULL)
+ while ((result = XLogReadRecord(state, tmpRecPtr, &record, &errormsg)) !=
+ XLREAD_FAIL)
{
/* continue after the record */
tmpRecPtr = InvalidXLogRecPtr;
+ 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)
{
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index dad9074b9f..d50a0ca187 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -802,8 +802,7 @@ XLogRead(char *buf, int segsize, TimeLineID tli, XLogRecPtr startptr,
void
XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wantLength)
{
- const XLogRecPtr lastReadPage = state->readSegNo *
- state->wal_segment_size + state->readLen;
+ const XLogRecPtr lastReadPage = state->readPagePtr;
Assert(wantPage != InvalidXLogRecPtr && wantPage % XLOG_BLCKSZ == 0);
Assert(wantLength <= XLOG_BLCKSZ);
@@ -818,7 +817,7 @@ 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;
@@ -908,10 +907,12 @@ XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wa
* loop for now.
*/
bool
-read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr,
- int reqLen, XLogRecPtr targetRecPtr, char *cur_page,
- TimeLineID *pageTLI)
+read_local_xlog_page(XLogReaderState *state)
{
+ XLogRecPtr targetPagePtr = state->readPagePtr;
+ int reqLen = state->readLen;
+ char *cur_page = state->readBuf;
+ TimeLineID *pageTLI = &state->readPageTLI;
XLogRecPtr read_upto,
loc;
int count;
@@ -1027,6 +1028,7 @@ read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr,
XLOG_BLCKSZ);
/* 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 f8b9020081..11e52e4c01 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -124,7 +124,7 @@ StartupDecodingContext(List *output_plugin_options,
TransactionId xmin_horizon,
bool need_full_snapshot,
bool fast_forward,
- XLogPageReadCB read_page,
+ LogicalDecodingXLogReadPageCB read_page,
LogicalOutputPluginWriterPrepareWrite prepare_write,
LogicalOutputPluginWriterWrite do_write,
LogicalOutputPluginWriterUpdateProgress update_progress)
@@ -173,11 +173,12 @@ StartupDecodingContext(List *output_plugin_options,
ctx->slot = slot;
- ctx->reader = XLogReaderAllocate(wal_segment_size, read_page, ctx);
+ ctx->reader = XLogReaderAllocate(wal_segment_size);
if (!ctx->reader)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
+ ctx->read_page = read_page;
ctx->reorder = ReorderBufferAllocate();
ctx->snapshot_builder =
@@ -232,7 +233,7 @@ CreateInitDecodingContext(char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
XLogRecPtr restart_lsn,
- XLogPageReadCB read_page,
+ LogicalDecodingXLogReadPageCB read_page,
LogicalOutputPluginWriterPrepareWrite prepare_write,
LogicalOutputPluginWriterWrite do_write,
LogicalOutputPluginWriterUpdateProgress update_progress)
@@ -374,7 +375,7 @@ LogicalDecodingContext *
CreateDecodingContext(XLogRecPtr start_lsn,
List *output_plugin_options,
bool fast_forward,
- XLogPageReadCB read_page,
+ LogicalDecodingXLogReadPageCB read_page,
LogicalOutputPluginWriterPrepareWrite prepare_write,
LogicalOutputPluginWriterWrite do_write,
LogicalOutputPluginWriterUpdateProgress update_progress)
@@ -482,7 +483,13 @@ DecodingContextFindStartpoint(LogicalDecodingContext *ctx)
char *err = NULL;
/* the read_page callback waits for new WAL */
- record = XLogReadRecord(ctx->reader, startptr, &err);
+ while (XLogReadRecord(ctx->reader, startptr, &record, &err) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!ctx->read_page(ctx))
+ 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 7210a940bd..5270f646bd 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,11 +115,9 @@ check_permissions(void)
}
bool
-logical_read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr,
- int reqLen, XLogRecPtr targetRecPtr, char *cur_page, TimeLineID *pageTLI)
+logical_read_local_xlog_page(LogicalDecodingContext *ctx)
{
- return read_local_xlog_page(state, targetPagePtr, reqLen,
- targetRecPtr, cur_page, pageTLI);
+ return read_local_xlog_page(ctx->reader);
}
/*
@@ -289,7 +287,13 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
XLogRecord *record;
char *errm = NULL;
- record = XLogReadRecord(ctx->reader, startptr, &errm);
+ while (XLogReadRecord(ctx->reader, startptr, &record, &errm) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!ctx->read_page(ctx))
+ break;
+ }
+
if (errm)
elog(ERROR, "%s", errm);
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 808a6f5b83..fb5c0a702d 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -433,7 +433,13 @@ 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, startlsn, &errm);
+ while (XLogReadRecord(ctx->reader, startlsn, &record, &errm) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!ctx->read_page(ctx))
+ break;
+ }
+
if (errm)
elog(ERROR, "%s", errm);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index cc35e2a04d..a4518f5b55 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -762,9 +762,12 @@ 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, TimeLineID *pageTLI)
+logical_read_xlog_page(LogicalDecodingContext *ctx)
{
+ XLogReaderState *state = ctx->reader;
+ XLogRecPtr targetPagePtr = state->readPagePtr;
+ int reqLen = state->readLen;
+ char *cur_page = state->readBuf;
XLogRecPtr flushptr;
int count;
@@ -2827,7 +2830,12 @@ XLogSendLogical(void)
*/
WalSndCaughtUp = false;
- record = XLogReadRecord(logical_decoding_ctx->reader, logical_startptr, &errm);
+ while (XLogReadRecord(logical_decoding_ctx->reader,
+ logical_startptr, &record, &errm) == XLREAD_NEED_DATA)
+ {
+ if (!logical_decoding_ctx->read_page(logical_decoding_ctx))
+ break;
+ }
logical_startptr = InvalidXLogRecPtr;
/* xlog record was invalid */
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 4df53964e4..ff26b30f82 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -41,16 +41,8 @@ static int xlogreadfd = -1;
static XLogSegNo xlogreadsegno = -1;
static char xlogfpath[MAXPGPATH];
-typedef struct XLogPageReadPrivate
-{
- const char *datadir;
- int tliIndex;
-} XLogPageReadPrivate;
-
-static bool SimpleXLogPageRead(XLogReaderState *xlogreader,
- XLogRecPtr targetPagePtr,
- int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
- TimeLineID *pageTLI);
+static bool SimpleXLogPageRead(XLogReaderState *xlogreader,
+ const char *datadir, int *tliIndex);
/*
* Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
@@ -64,24 +56,26 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
XLogRecord *record;
XLogReaderState *xlogreader;
char *errormsg;
- XLogPageReadPrivate private;
- private.datadir = datadir;
- private.tliIndex = tliIndex;
- xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
- &private);
+ xlogreader = XLogReaderAllocate(WalSegSz);
if (xlogreader == NULL)
pg_fatal("out of memory");
do
{
- record = XLogReadRecord(xlogreader, startpoint, &errormsg);
+ while (XLogReadRecord(xlogreader, startpoint, &record, &errormsg) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!SimpleXLogPageRead(xlogreader, datadir, &tliIndex))
+ break;
+ }
if (record == NULL)
{
- XLogRecPtr errptr;
+ XLogRecPtr errptr = xlogreader->EndRecPtr;
- errptr = startpoint ? startpoint : xlogreader->EndRecPtr;
+ if (startpoint)
+ errptr = startpoint;
if (errormsg)
pg_fatal("could not read WAL record at %X/%X: %s",
@@ -116,17 +110,18 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
XLogRecord *record;
XLogReaderState *xlogreader;
char *errormsg;
- XLogPageReadPrivate private;
XLogRecPtr endptr;
- private.datadir = datadir;
- private.tliIndex = tliIndex;
- xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
- &private);
+ xlogreader = XLogReaderAllocate(WalSegSz);
if (xlogreader == NULL)
pg_fatal("out of memory");
- record = XLogReadRecord(xlogreader, ptr, &errormsg);
+ while (XLogReadRecord(xlogreader, ptr, &record, &errormsg) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!SimpleXLogPageRead(xlogreader, datadir, &tliIndex))
+ break;
+ }
if (record == NULL)
{
if (errormsg)
@@ -161,7 +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,
@@ -177,10 +171,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
forkptr += SizeOfXLogShortPHD;
}
- private.datadir = datadir;
- private.tliIndex = tliIndex;
- xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
- &private);
+ xlogreader = XLogReaderAllocate(WalSegSz);
if (xlogreader == NULL)
pg_fatal("out of memory");
@@ -189,7 +180,12 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
{
uint8 info;
- record = XLogReadRecord(xlogreader, searchptr, &errormsg);
+ while (XLogReadRecord(xlogreader, searchptr, &record, &errormsg) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!SimpleXLogPageRead(xlogreader, datadir, &tliIndex))
+ break;
+ }
if (record == NULL)
{
@@ -236,11 +232,12 @@ 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,
- TimeLineID *pageTLI)
+SimpleXLogPageRead(XLogReaderState *xlogreader,
+ const char*datadir, int *tliIndex)
{
- XLogPageReadPrivate *private = (XLogPageReadPrivate *) xlogreader->private_data;
+ XLogRecPtr targetPagePtr = xlogreader->readPagePtr;
+ char *readBuf = xlogreader->readBuf;
+ TimeLineID *pageTLI = &xlogreader->readPageTLI;
uint32 targetPageOff;
XLogRecPtr targetSegEnd;
XLogSegNo targetSegNo;
@@ -273,17 +270,17 @@ 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", private->datadir, xlogfname);
+ snprintf(xlogfpath, MAXPGPATH, "%s/" XLOGDIR "/%s", datadir, xlogfname);
xlogreadfd = open(xlogfpath, O_RDONLY | PG_BINARY, 0);
@@ -324,7 +321,7 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
Assert(targetSegNo == xlogreadsegno);
- *pageTLI = targetHistory[private->tliIndex].tli;
+ *pageTLI = 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 96d1f36ebc..a61a5a91cb 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -422,10 +422,12 @@ XLogDumpXLogRead(const char *directory, TimeLineID timeline_id,
* XLogReader read_page callback
*/
static bool
-XLogDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
- XLogRecPtr targetPtr, char *readBuff, TimeLineID *curFileTLI)
+XLogDumpReadPage(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;
if (private->endptr != InvalidXLogRecPtr)
@@ -445,6 +447,7 @@ XLogDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
XLogDumpXLogRead(private->inpath, private->timeline, targetPagePtr,
readBuff, count);
+ Assert(count >= state->readLen);
state->readLen = count;
return true;
}
@@ -1102,13 +1105,13 @@ main(int argc, char **argv)
/* done with argument parsing, do the actual work */
/* we have everything we need, start reading */
- xlogreader_state = XLogReaderAllocate(WalSegSz, XLogDumpReadPage,
- &private);
+ xlogreader_state = XLogReaderAllocate(WalSegSz);
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,
+ &XLogDumpReadPage, (void*) &private);
if (first_record == InvalidXLogRecPtr)
fatal_error("could not find a valid record after %X/%X",
@@ -1132,7 +1135,14 @@ main(int argc, char **argv)
for (;;)
{
/* try to read the next record */
- record = XLogReadRecord(xlogreader_state, first_record, &errormsg);
+ while (XLogReadRecord(xlogreader_state,
+ first_record, &record, &errormsg) ==
+ XLREAD_NEED_DATA)
+ {
+ if (!XLogDumpReadPage(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 6de7c19a2a..11ae82b96d 100644
--- a/src/include/access/xlogreader.h
+++ b/src/include/access/xlogreader.h
@@ -33,14 +33,6 @@
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,
- TimeLineID *pageTLI);
-
typedef struct
{
/* Is this block ref in use? */
@@ -70,6 +62,29 @@ 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
{
/* ----------------------------------------
@@ -82,46 +97,19 @@ struct XLogReaderState
*/
int wal_segment_size;
- /*
- * Data input callback (mandatory).
- *
- * 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 *pageTLI to the TLI of the file the page was
- * read from. It is currently used only for error reporting purposes, to
- * reconstruct the name of the WAL file where an error occurred.
- */
- XLogPageReadCB read_page;
-
/*
* System identifier of the xlog files we're about to read. Set to zero
* (the default value) if unknown or unimportant.
*/
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, if XLogReadRecord receives an invalid recptr.
*/
- 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
@@ -163,6 +151,7 @@ struct XLogReaderState
/* last read segment and segment offset for data currently in readBuf */
bool page_verified;
+ bool record_verified;
XLogSegNo readSegNo;
/*
@@ -172,8 +161,6 @@ 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;
@@ -200,28 +187,41 @@ 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;
};
/* Get a new XLogReader */
-extern XLogReaderState *XLogReaderAllocate(int wal_segment_size,
- XLogPageReadCB pagereadfunc,
- void *private_data);
+extern XLogReaderState *XLogReaderAllocate(int wal_segment_size);
/* Free an XLogReader */
extern void XLogReaderFree(XLogReaderState *state);
/* Read the next XLog record. Returns NULL on end-of-WAL or failure */
-extern struct XLogRecord *XLogReadRecord(XLogReaderState *state,
- XLogRecPtr recptr, char **errormsg);
+extern XLogReadRecordResult XLogReadRecord(XLogReaderState *state,
+ XLogRecPtr recptr,
+ XLogRecord **record,
+ char **errormsg);
/* Validate a page */
extern bool XLogReaderValidatePageHeader(XLogReaderState *state,
XLogRecPtr recptr, char *phdr);
#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 */
/* Functions for decoding an XLogRecord */
diff --git a/src/include/access/xlogutils.h b/src/include/access/xlogutils.h
index 0842af9f95..55a9b6237a 100644
--- a/src/include/access/xlogutils.h
+++ b/src/include/access/xlogutils.h
@@ -47,10 +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,
- TimeLineID *pageTLI);
+extern bool read_local_xlog_page(XLogReaderState *state);
extern void XLogReadDetermineTimeline(XLogReaderState *state,
XLogRecPtr wantPage, uint32 wantLength);
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index 31c796b765..482d3d311c 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -30,6 +30,10 @@ typedef void (*LogicalOutputPluginWriterUpdateProgress) (struct LogicalDecodingC
TransactionId xid
);
+typedef struct LogicalDecodingContext LogicalDecodingContext;
+
+typedef bool (*LogicalDecodingXLogReadPageCB)(LogicalDecodingContext *ctx);
+
typedef struct LogicalDecodingContext
{
/* memory context this is all allocated in */
@@ -40,6 +44,7 @@ typedef struct LogicalDecodingContext
/* infrastructure pieces for decoding */
XLogReaderState *reader;
+ LogicalDecodingXLogReadPageCB read_page;
struct ReorderBuffer *reorder;
struct SnapBuild *snapshot_builder;
@@ -96,14 +101,14 @@ extern LogicalDecodingContext *CreateInitDecodingContext(char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
XLogRecPtr restart_lsn,
- XLogPageReadCB read_page,
+ LogicalDecodingXLogReadPageCB read_page,
LogicalOutputPluginWriterPrepareWrite prepare_write,
LogicalOutputPluginWriterWrite do_write,
LogicalOutputPluginWriterUpdateProgress update_progress);
extern LogicalDecodingContext *CreateDecodingContext(XLogRecPtr start_lsn,
List *output_plugin_options,
bool fast_forward,
- XLogPageReadCB read_page,
+ LogicalDecodingXLogReadPageCB read_page,
LogicalOutputPluginWriterPrepareWrite prepare_write,
LogicalOutputPluginWriterWrite do_write,
LogicalOutputPluginWriterUpdateProgress update_progress);
diff --git a/src/include/replication/logicalfuncs.h b/src/include/replication/logicalfuncs.h
index 8e52b1f4aa..25fa68d5b9 100644
--- a/src/include/replication/logicalfuncs.h
+++ b/src/include/replication/logicalfuncs.h
@@ -11,9 +11,6 @@
#include "replication/logical.h"
-extern bool logical_read_local_xlog_page(XLogReaderState *state,
- XLogRecPtr targetPagePtr,
- int reqLen, XLogRecPtr targetRecPtr,
- char *cur_page, TimeLineID *pageTLI);
+extern bool logical_read_local_xlog_page(LogicalDecodingContext *ctx);
#endif
--
2.16.3
From 540c683f9702a0e27a593d29019e125304a6ea7a 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 v6 3/4] Remove globals readSegNo, readOff, readLen
These global variables is functionally duplicated with them in
XLogReaderState. Remove the globals.
---
src/backend/access/transam/xlog.c | 77 ++++++++++++++++++---------------------
src/include/access/xlogreader.h | 2 +-
2 files changed, 36 insertions(+), 43 deletions(-)
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 34ab4ea359..c20d3b1418 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -783,14 +783,10 @@ 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.
*/
static int readFile = -1;
-static XLogSegNo readSegNo = 0;
-static uint32 readOff = 0;
-static uint32 readLen = 0;
static XLogSource readSource = 0; /* XLOG_FROM_* code */
/*
@@ -877,10 +873,12 @@ static bool InstallXLogFileSegment(XLogSegNo *segno, char *tmppath,
static int XLogFileRead(XLogSegNo segno, int emode, TimeLineID tli,
int source, bool notfoundOk);
static int XLogFileReadAnyTLI(XLogSegNo segno, int emode, int 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);
@@ -7494,7 +7492,8 @@ 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);
@@ -11514,14 +11513,15 @@ 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;
- TimeLineID *readTLI = &xlogreader->readPageTLI;
+ char *readBuf = state->readBuf;
+ XLogRecPtr targetPagePtr = state->readPagePtr;
+ int reqLen = state->readLen;
+ int readLen = 0;
+ XLogRecPtr targetRecPtr = state->ReadRecPtr;
+ TimeLineID *readTLI = &state->readPageTLI;
uint32 targetPageOff;
XLogSegNo targetSegNo PG_USED_FOR_ASSERTS_ONLY;
int r;
@@ -11534,7 +11534,7 @@ 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
@@ -11542,10 +11542,10 @@ 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);
}
}
@@ -11555,7 +11555,7 @@ XLogPageRead(XLogReaderState *xlogreader,
readSource = 0;
}
- XLByteToSeg(targetPagePtr, readSegNo, wal_segment_size);
+ XLByteToSeg(targetPagePtr, state->readSegNo, wal_segment_size);
retry:
/* See if we need to retrieve more data */
@@ -11564,17 +11564,14 @@ retry:
receivedUpto < 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 = 0;
-
- xlogreader->readLen = -1;
+ state->readLen = -1;
return false;
}
}
@@ -11602,37 +11599,33 @@ 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);
*readTLI = curFileTLI;
@@ -11663,15 +11656,15 @@ 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:
@@ -11680,14 +11673,13 @@ next_record_is_invalid:
if (readFile >= 0)
close(readFile);
readFile = -1;
- readLen = 0;
readSource = 0;
/* In standby-mode, keep trying */
if (StandbyMode)
goto retry;
- xlogreader->readLen = -1;
+ state->readLen = -1;
return false;
}
@@ -11719,7 +11711,8 @@ 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 11ae82b96d..aca15be216 100644
--- a/src/include/access/xlogreader.h
+++ b/src/include/access/xlogreader.h
@@ -122,6 +122,7 @@ 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 */
/* ----------------------------------------
@@ -152,7 +153,6 @@ struct XLogReaderState
/* last read segment and segment offset for data currently in readBuf */
bool page_verified;
bool record_verified;
- XLogSegNo readSegNo;
/*
* beginning of prior page read, and its TLI. Doesn't necessarily
--
2.16.3
From a6f261d8454e61184142af91b0bf2a4811d78182 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 v6 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 | 18 ------------------
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(+), 18 deletions(-)
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index a736504d62..358951c232 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -1392,6 +1392,7 @@ 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);
while (XLogReadRecord(xlogreader, lsn, &record, &errormsg) ==
XLREAD_NEED_DATA)
@@ -1421,6 +1422,7 @@ 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 c20d3b1418..a199600399 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6349,6 +6349,7 @@ 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;
/*
@@ -7721,6 +7722,7 @@ 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 e00fa270ae..1f98dd0168 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -80,27 +80,11 @@ XLogReaderAllocate(int wal_segment_size)
state->max_block_id = -1;
- /*
- * Permanently allocate readBuf. We do it this way, rather than just
- * making a static array, for two reasons: (1) no need to waste the
- * storage in most instantiations of the backend; (2) a static char array
- * isn't guaranteed to have any particular alignment, whereas
- * palloc_extended() will provide MAXALIGN'd storage.
- */
- state->readBuf = (char *) palloc_extended(XLOG_BLCKSZ,
- MCXT_ALLOC_NO_OOM);
- if (!state->readBuf)
- {
- pfree(state);
- return NULL;
- }
-
state->wal_segment_size = wal_segment_size;
state->errormsg_buf = palloc_extended(MAX_ERRORMSG_LEN + 1,
MCXT_ALLOC_NO_OOM);
if (!state->errormsg_buf)
{
- pfree(state->readBuf);
pfree(state);
return NULL;
}
@@ -113,7 +97,6 @@ XLogReaderAllocate(int wal_segment_size)
if (!allocate_recordbuf(state, 0))
{
pfree(state->errormsg_buf);
- pfree(state->readBuf);
pfree(state);
return NULL;
}
@@ -137,7 +120,6 @@ 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 11e52e4c01..ea027caa69 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -178,6 +178,7 @@ StartupDecodingContext(List *output_plugin_options,
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
+ ctx->reader->readBuf = palloc(XLOG_BLCKSZ);
ctx->read_page = read_page;
ctx->reorder = ReorderBufferAllocate();
@@ -523,6 +524,7 @@ 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 ff26b30f82..c60267e87e 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -60,6 +60,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
xlogreader = XLogReaderAllocate(WalSegSz);
if (xlogreader == NULL)
pg_fatal("out of memory");
+ xlogreader->readBuf = pg_malloc(XLOG_BLCKSZ);
do
{
@@ -92,6 +93,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
} while (xlogreader->ReadRecPtr != endpoint);
+ pg_free(xlogreader->readBuf);
XLogReaderFree(xlogreader);
if (xlogreadfd != -1)
{
@@ -115,6 +117,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
xlogreader = XLogReaderAllocate(WalSegSz);
if (xlogreader == NULL)
pg_fatal("out of memory");
+ xlogreader->readBuf = pg_malloc(XLOG_BLCKSZ);
while (XLogReadRecord(xlogreader, ptr, &record, &errormsg) ==
XLREAD_NEED_DATA)
@@ -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);
if (xlogreader == NULL)
pg_fatal("out of memory");
+ xlogreader->readBuf = pg_malloc(XLOG_BLCKSZ);
searchptr = forkptr;
for (;;)
@@ -222,6 +227,7 @@ 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 a61a5a91cb..5eba802720 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -1108,6 +1108,7 @@ main(int argc, char **argv)
xlogreader_state = XLogReaderAllocate(WalSegSz);
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,
@@ -1188,6 +1189,7 @@ main(int argc, char **argv)
(uint32) xlogreader_state->ReadRecPtr,
errormsg);
+ pfree(xlogreader_state->readBuf);
XLogReaderFree(xlogreader_state);
return EXIT_SUCCESS;
--
2.16.3
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