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[PATCH 5/5] Remove the old implemenations of XLogRead().
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* [PATCH 5/5] Remove the old implemenations of XLogRead().
@ 2019-07-09 09:54  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 9+ messages in thread

From: Antonin Houska @ 2019-07-09 09:54 UTC (permalink / raw)

Done in a separate patch because the diff looks harder to read if one function
(XLogRead) is removed and another one (the XLogOpenSegment callback) is added
nearby at the same time (the addition and removal of code can get mixed in the
diff).
---
 src/backend/access/transam/xlogutils.c | 125 ----------------------
 src/backend/replication/walsender.c    | 186 ---------------------------------
 src/bin/pg_waldump/pg_waldump.c        | 123 ----------------------
 3 files changed, 434 deletions(-)

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 899bf1b551..c35852d7a1 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -17,14 +17,11 @@
  */
 #include "postgres.h"
 
-#include <unistd.h>
-
 #include "access/timeline.h"
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
 #include "access/xlogutils.h"
 #include "miscadmin.h"
-#include "pgstat.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/hsearch.h"
@@ -639,128 +636,6 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
 	forget_invalid_pages(rnode, forkNum, nblocks);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- * in timeline 'tli'.
- *
- * Will open, and keep open, one WAL segment stored in the static file
- * descriptor 'sendFile'. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- *
- * XXX This is very similar to pg_waldump's XLogDumpXLogRead and to XLogRead
- * in walsender.c but for small differences (such as lack of elog() in
- * frontend).  Probably these should be merged at some point.
- */
-static void
-XLogReadOld(char *buf, int segsize, TimeLineID tli, XLogRecPtr startptr,
-			Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	/* state maintained across calls */
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static TimeLineID sendTLI = 0;
-	static uint32 sendOff = 0;
-
-	Assert(segsize == wal_segment_size);
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segsize);
-
-		/* Do we need to switch to a different xlog segment? */
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, segsize) ||
-			sendTLI != tli)
-		{
-			char		path[MAXPGPATH];
-
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, segsize);
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-
-			sendFile = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-
-			if (sendFile < 0)
-			{
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									path)));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendOff = 0;
-			sendTLI = tli;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				char		path[MAXPGPATH];
-				int			save_errno = errno;
-
-				XLogFilePath(path, tli, sendSegNo, segsize);
-				errno = save_errno;
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								path, startoff)));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segsize - startoff))
-			segbytes = segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendFile, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes <= 0)
-		{
-			char		path[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-			errno = save_errno;
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %lu: %m",
-							path, sendOff, (unsigned long) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * Determine which timeline to read an xlog page from and set the
  * XLogReaderState's currTLI to that timeline ID.
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index c64a4bf9f8..68715aed9e 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -249,7 +249,6 @@ static bool TransactionIdInRecentPast(TransactionId xid, uint32 epoch);
 
 static void WalSndOpenSegment(XLogSegNo nextSegNo, TimeLineID *tli,
 							  XLogSegment *seg);
-static void XLogReadOld(char *buf, XLogRecPtr startptr, Size count);
 
 
 /* Initialize walsender process before entering the main command loop */
@@ -2351,191 +2350,6 @@ WalSndKill(int code, Datum arg)
 	SpinLockRelease(&walsnd->mutex);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- *
- * XXX probably this should be improved to suck data directly from the
- * WAL buffers when possible.
- *
- * Will open, and keep open, one WAL segment stored in the global file
- * descriptor sendFile. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- */
-static void
-XLogReadOld(char *buf, XLogRecPtr startptr, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-	XLogSegNo	segno;
-
-retry:
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, wal_segment_size);
-
-		if (sendSeg->file < 0 ||
-			!XLByteInSeg(recptr, sendSeg->num, sendSeg->size))
-		{
-			char		path[MAXPGPATH];
-
-			/* Switch to another logfile segment */
-			if (sendSeg->file >= 0)
-				close(sendSeg->file);
-
-			XLByteToSeg(recptr, sendSeg->num, sendSeg->size);
-
-			/*-------
-			 * When reading from a historic timeline, and there is a timeline
-			 * switch within this segment, read from the WAL segment belonging
-			 * to the new timeline.
-			 *
-			 * For example, imagine that this server is currently on timeline
-			 * 5, and we're streaming timeline 4. The switch from timeline 4
-			 * to 5 happened at 0/13002088. In pg_wal, we have these files:
-			 *
-			 * ...
-			 * 000000040000000000000012
-			 * 000000040000000000000013
-			 * 000000050000000000000013
-			 * 000000050000000000000014
-			 * ...
-			 *
-			 * In this situation, when requested to send the WAL from
-			 * segment 0x13, on timeline 4, we read the WAL from file
-			 * 000000050000000000000013. Archive recovery prefers files from
-			 * newer timelines, so if the segment was restored from the
-			 * archive on this server, the file belonging to the old timeline,
-			 * 000000040000000000000013, might not exist. Their contents are
-			 * equal up to the switchpoint, because at a timeline switch, the
-			 * used portion of the old segment is copied to the new file.
-			 *-------
-			 */
-			sendSeg->tli = sendTimeLine;
-			if (sendTimeLineIsHistoric)
-			{
-				XLogSegNo	endSegNo;
-
-				XLByteToSeg(sendTimeLineValidUpto, endSegNo, wal_segment_size);
-				if (sendSeg->num == endSegNo)
-					sendSeg->tli = sendTimeLineNextTLI;
-			}
-
-			XLogFilePath(path, sendSeg->tli, sendSeg->num, wal_segment_size);
-
-			sendSeg->file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-			if (sendSeg->file < 0)
-			{
-				/*
-				 * If the file is not found, assume it's because the standby
-				 * asked for a too old WAL segment that has already been
-				 * removed or recycled.
-				 */
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									XLogFileNameP(sendSeg->tli, sendSeg->num))));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendSeg->off = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendSeg->off != startoff)
-		{
-			if (lseek(sendSeg->file, (off_t) startoff, SEEK_SET) < 0)
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								XLogFileNameP(sendSeg->tli, sendSeg->num),
-								startoff)));
-			sendSeg->off = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (wal_segment_size - startoff))
-			segbytes = wal_segment_size - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendSeg->file, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes < 0)
-		{
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %zu: %m",
-							XLogFileNameP(sendSeg->tli, sendSeg->num),
-							sendSeg->off, (Size) segbytes)));
-		}
-		else if (readbytes == 0)
-		{
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg("could not read from log segment %s, offset %u: read %d of %zu",
-							XLogFileNameP(sendSeg->tli, sendSeg->num),
-							sendSeg->off, readbytes, (Size) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendSeg->off += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-
-	/*
-	 * After reading into the buffer, check that what we read was valid. We do
-	 * this after reading, because even though the segment was present when we
-	 * opened it, it might get recycled or removed while we read it. The
-	 * read() succeeds in that case, but the data we tried to read might
-	 * already have been overwritten with new WAL records.
-	 */
-	XLByteToSeg(startptr, segno, wal_segment_size);
-	CheckXLogRemoved(segno, ThisTimeLineID);
-
-	/*
-	 * During recovery, the currently-open WAL file might be replaced with the
-	 * file of the same name retrieved from archive. So we always need to
-	 * check what we read was valid after reading into the buffer. If it's
-	 * invalid, we try to open and read the file again.
-	 */
-	if (am_cascading_walsender)
-	{
-		WalSnd	   *walsnd = MyWalSnd;
-		bool		reload;
-
-		SpinLockAcquire(&walsnd->mutex);
-		reload = walsnd->needreload;
-		walsnd->needreload = false;
-		SpinLockRelease(&walsnd->mutex);
-
-		if (reload && sendSeg->file >= 0)
-		{
-			close(sendSeg->file);
-			sendSeg->file = -1;
-
-			goto retry;
-		}
-	}
-}
-
 /*
  * Callback for XLogRead() to open the next segment.
  */
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index 3e09519f88..cd44090d36 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -14,7 +14,6 @@
 
 #include <dirent.h>
 #include <sys/stat.h>
-#include <unistd.h>
 
 #include "access/xlogreader.h"
 #include "access/xlogrecord.h"
@@ -335,128 +334,6 @@ XLogDumpOpenSegment(XLogSegNo nextSegNo, TimeLineID *tli, XLogSegment *seg)
 	seg->tli = *tli;
 }
 
-/*
- * Read count bytes from a segment file in the specified directory, for the
- * given timeline, containing the specified record pointer; store the data in
- * the passed buffer.
- */
-static void
-XLogDumpXLogRead(const char *directory, TimeLineID timeline_id,
-				 XLogRecPtr startptr, char *buf, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static uint32 sendOff = 0;
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, WalSegSz);
-
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, WalSegSz))
-		{
-			char		fname[MAXFNAMELEN];
-			int			tries;
-
-			/* Switch to another logfile segment */
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, WalSegSz);
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-			/*
-			 * In follow mode there is a short period of time after the server
-			 * has written the end of the previous file before the new file is
-			 * available. So we loop for 5 seconds looking for the file to
-			 * appear before giving up.
-			 */
-			for (tries = 0; tries < 10; tries++)
-			{
-				sendFile = open_file_in_directory(directory, fname);
-				if (sendFile >= 0)
-					break;
-				if (errno == ENOENT)
-				{
-					int			save_errno = errno;
-
-					/* File not there yet, try again */
-					pg_usleep(500 * 1000);
-
-					errno = save_errno;
-					continue;
-				}
-				/* Any other error, fall through and fail */
-				break;
-			}
-
-			if (sendFile < 0)
-				fatal_error("could not find file \"%s\": %s",
-							fname, strerror(errno));
-			sendOff = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				int			err = errno;
-				char		fname[MAXPGPATH];
-
-				XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-				fatal_error("could not seek in log file %s to offset %u: %s",
-							fname, startoff, strerror(err));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (WalSegSz - startoff))
-			segbytes = WalSegSz - startoff;
-		else
-			segbytes = nbytes;
-
-		readbytes = read(sendFile, p, segbytes);
-		if (readbytes <= 0)
-		{
-			int			err = errno;
-			char		fname[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-			errno = save_errno;
-
-			if (readbytes < 0)
-				fatal_error("could not read from log file %s, offset %u, length %d: %s",
-							fname, sendOff, segbytes, strerror(err));
-			else if (readbytes == 0)
-				fatal_error("could not read from log file %s, offset %u: read %d of %zu",
-							fname, sendOff, readbytes, (Size) segbytes);
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * XLogReader read_page callback
  */
-- 
2.16.4


--=-=-=--





^ permalink  raw  reply  [nested|flat] 9+ messages in thread

* [PATCH 4/4] Remove the old implemenations of XLogRead().
@ 2019-09-09 09:53  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 9+ messages in thread

From: Antonin Houska @ 2019-09-09 09:53 UTC (permalink / raw)

Done in a separate patch because the diff looks harder to read if one function
(XLogRead) is removed and another one (the XLogOpenSegment callback) is added
nearby at the same time (the addition and removal of code can get mixed in the
diff).
---
 src/backend/access/transam/xlogutils.c | 125 -----------------
 src/backend/replication/walsender.c    | 186 -------------------------
 src/bin/pg_waldump/pg_waldump.c        | 123 ----------------
 3 files changed, 434 deletions(-)

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 83b014e04c..5b0ba39f17 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -17,14 +17,11 @@
  */
 #include "postgres.h"
 
-#include <unistd.h>
-
 #include "access/timeline.h"
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
 #include "access/xlogutils.h"
 #include "miscadmin.h"
-#include "pgstat.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/hsearch.h"
@@ -639,128 +636,6 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
 	forget_invalid_pages(rnode, forkNum, nblocks);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- * in timeline 'tli'.
- *
- * Will open, and keep open, one WAL segment stored in the static file
- * descriptor 'sendFile'. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- *
- * XXX This is very similar to pg_waldump's XLogDumpXLogRead and to XLogRead
- * in walsender.c but for small differences (such as lack of elog() in
- * frontend).  Probably these should be merged at some point.
- */
-static void
-XLogReadOld(char *buf, int segsize, TimeLineID tli, XLogRecPtr startptr,
-			Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	/* state maintained across calls */
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static TimeLineID sendTLI = 0;
-	static uint32 sendOff = 0;
-
-	Assert(segsize == wal_segment_size);
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segsize);
-
-		/* Do we need to switch to a different xlog segment? */
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, segsize) ||
-			sendTLI != tli)
-		{
-			char		path[MAXPGPATH];
-
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, segsize);
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-
-			sendFile = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-
-			if (sendFile < 0)
-			{
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									path)));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendOff = 0;
-			sendTLI = tli;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				char		path[MAXPGPATH];
-				int			save_errno = errno;
-
-				XLogFilePath(path, tli, sendSegNo, segsize);
-				errno = save_errno;
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								path, startoff)));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segsize - startoff))
-			segbytes = segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendFile, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes <= 0)
-		{
-			char		path[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-			errno = save_errno;
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %lu: %m",
-							path, sendOff, (unsigned long) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * Determine which timeline to read an xlog page from and set the
  * XLogReaderState's currTLI to that timeline ID.
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 0685c320b4..072d46d853 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -249,7 +249,6 @@ static bool TransactionIdInRecentPast(TransactionId xid, uint32 epoch);
 
 static void WalSndOpenSegment(XLogSegNo nextSegNo, TimeLineID *tli,
 							  XLogSegment *seg);
-static void XLogReadOld(char *buf, XLogRecPtr startptr, Size count);
 
 
 /* Initialize walsender process before entering the main command loop */
@@ -2351,191 +2350,6 @@ WalSndKill(int code, Datum arg)
 	SpinLockRelease(&walsnd->mutex);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- *
- * XXX probably this should be improved to suck data directly from the
- * WAL buffers when possible.
- *
- * Will open, and keep open, one WAL segment stored in the global file
- * descriptor sendFile. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- */
-static void
-XLogReadOld(char *buf, XLogRecPtr startptr, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-	XLogSegNo	segno;
-
-retry:
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, wal_segment_size);
-
-		if (sendSeg->file < 0 ||
-			!XLByteInSeg(recptr, sendSeg->num, sendSeg->size))
-		{
-			char		path[MAXPGPATH];
-
-			/* Switch to another logfile segment */
-			if (sendSeg->file >= 0)
-				close(sendSeg->file);
-
-			XLByteToSeg(recptr, sendSeg->num, sendSeg->size);
-
-			/*-------
-			 * When reading from a historic timeline, and there is a timeline
-			 * switch within this segment, read from the WAL segment belonging
-			 * to the new timeline.
-			 *
-			 * For example, imagine that this server is currently on timeline
-			 * 5, and we're streaming timeline 4. The switch from timeline 4
-			 * to 5 happened at 0/13002088. In pg_wal, we have these files:
-			 *
-			 * ...
-			 * 000000040000000000000012
-			 * 000000040000000000000013
-			 * 000000050000000000000013
-			 * 000000050000000000000014
-			 * ...
-			 *
-			 * In this situation, when requested to send the WAL from
-			 * segment 0x13, on timeline 4, we read the WAL from file
-			 * 000000050000000000000013. Archive recovery prefers files from
-			 * newer timelines, so if the segment was restored from the
-			 * archive on this server, the file belonging to the old timeline,
-			 * 000000040000000000000013, might not exist. Their contents are
-			 * equal up to the switchpoint, because at a timeline switch, the
-			 * used portion of the old segment is copied to the new file.
-			 *-------
-			 */
-			sendSeg->tli = sendTimeLine;
-			if (sendTimeLineIsHistoric)
-			{
-				XLogSegNo	endSegNo;
-
-				XLByteToSeg(sendTimeLineValidUpto, endSegNo, wal_segment_size);
-				if (sendSeg->num == endSegNo)
-					sendSeg->tli = sendTimeLineNextTLI;
-			}
-
-			XLogFilePath(path, sendSeg->tli, sendSeg->num, wal_segment_size);
-
-			sendSeg->file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-			if (sendSeg->file < 0)
-			{
-				/*
-				 * If the file is not found, assume it's because the standby
-				 * asked for a too old WAL segment that has already been
-				 * removed or recycled.
-				 */
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									XLogFileNameP(sendSeg->tli, sendSeg->num))));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendSeg->off = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendSeg->off != startoff)
-		{
-			if (lseek(sendSeg->file, (off_t) startoff, SEEK_SET) < 0)
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								XLogFileNameP(sendSeg->tli, sendSeg->num),
-								startoff)));
-			sendSeg->off = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (wal_segment_size - startoff))
-			segbytes = wal_segment_size - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendSeg->file, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes < 0)
-		{
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %zu: %m",
-							XLogFileNameP(sendSeg->tli, sendSeg->num),
-							sendSeg->off, (Size) segbytes)));
-		}
-		else if (readbytes == 0)
-		{
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg("could not read from log segment %s, offset %u: read %d of %zu",
-							XLogFileNameP(sendSeg->tli, sendSeg->num),
-							sendSeg->off, readbytes, (Size) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendSeg->off += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-
-	/*
-	 * After reading into the buffer, check that what we read was valid. We do
-	 * this after reading, because even though the segment was present when we
-	 * opened it, it might get recycled or removed while we read it. The
-	 * read() succeeds in that case, but the data we tried to read might
-	 * already have been overwritten with new WAL records.
-	 */
-	XLByteToSeg(startptr, segno, wal_segment_size);
-	CheckXLogRemoved(segno, ThisTimeLineID);
-
-	/*
-	 * During recovery, the currently-open WAL file might be replaced with the
-	 * file of the same name retrieved from archive. So we always need to
-	 * check what we read was valid after reading into the buffer. If it's
-	 * invalid, we try to open and read the file again.
-	 */
-	if (am_cascading_walsender)
-	{
-		WalSnd	   *walsnd = MyWalSnd;
-		bool		reload;
-
-		SpinLockAcquire(&walsnd->mutex);
-		reload = walsnd->needreload;
-		walsnd->needreload = false;
-		SpinLockRelease(&walsnd->mutex);
-
-		if (reload && sendSeg->file >= 0)
-		{
-			close(sendSeg->file);
-			sendSeg->file = -1;
-
-			goto retry;
-		}
-	}
-}
-
 /*
  * Callback for XLogRead() to open the next segment.
  */
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index 3e09519f88..cd44090d36 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -14,7 +14,6 @@
 
 #include <dirent.h>
 #include <sys/stat.h>
-#include <unistd.h>
 
 #include "access/xlogreader.h"
 #include "access/xlogrecord.h"
@@ -335,128 +334,6 @@ XLogDumpOpenSegment(XLogSegNo nextSegNo, TimeLineID *tli, XLogSegment *seg)
 	seg->tli = *tli;
 }
 
-/*
- * Read count bytes from a segment file in the specified directory, for the
- * given timeline, containing the specified record pointer; store the data in
- * the passed buffer.
- */
-static void
-XLogDumpXLogRead(const char *directory, TimeLineID timeline_id,
-				 XLogRecPtr startptr, char *buf, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static uint32 sendOff = 0;
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, WalSegSz);
-
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, WalSegSz))
-		{
-			char		fname[MAXFNAMELEN];
-			int			tries;
-
-			/* Switch to another logfile segment */
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, WalSegSz);
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-			/*
-			 * In follow mode there is a short period of time after the server
-			 * has written the end of the previous file before the new file is
-			 * available. So we loop for 5 seconds looking for the file to
-			 * appear before giving up.
-			 */
-			for (tries = 0; tries < 10; tries++)
-			{
-				sendFile = open_file_in_directory(directory, fname);
-				if (sendFile >= 0)
-					break;
-				if (errno == ENOENT)
-				{
-					int			save_errno = errno;
-
-					/* File not there yet, try again */
-					pg_usleep(500 * 1000);
-
-					errno = save_errno;
-					continue;
-				}
-				/* Any other error, fall through and fail */
-				break;
-			}
-
-			if (sendFile < 0)
-				fatal_error("could not find file \"%s\": %s",
-							fname, strerror(errno));
-			sendOff = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				int			err = errno;
-				char		fname[MAXPGPATH];
-
-				XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-				fatal_error("could not seek in log file %s to offset %u: %s",
-							fname, startoff, strerror(err));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (WalSegSz - startoff))
-			segbytes = WalSegSz - startoff;
-		else
-			segbytes = nbytes;
-
-		readbytes = read(sendFile, p, segbytes);
-		if (readbytes <= 0)
-		{
-			int			err = errno;
-			char		fname[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-			errno = save_errno;
-
-			if (readbytes < 0)
-				fatal_error("could not read from log file %s, offset %u, length %d: %s",
-							fname, sendOff, segbytes, strerror(err));
-			else if (readbytes == 0)
-				fatal_error("could not read from log file %s, offset %u: read %d of %zu",
-							fname, sendOff, readbytes, (Size) segbytes);
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * XLogReader read_page callback
  */
-- 
2.22.0


--=-=-=--





^ permalink  raw  reply  [nested|flat] 9+ messages in thread

* [PATCH 6/6] Remove the old implemenations of XLogRead().
@ 2019-09-23 05:40  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 9+ messages in thread

From: Antonin Houska @ 2019-09-23 05:40 UTC (permalink / raw)

Done in a separate patch because the diff looks harder to read if one function
(XLogRead) is removed and another one (the WALSegmentOpen callback) is added
nearby at the same time (the addition and removal of code can get mixed in the
diff).
---
 src/backend/access/transam/xlogutils.c | 125 -----------------
 src/backend/replication/walsender.c    | 187 -------------------------
 src/bin/pg_waldump/pg_waldump.c        | 123 ----------------
 3 files changed, 435 deletions(-)

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 38c3196168..078d58e34c 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -17,14 +17,11 @@
  */
 #include "postgres.h"
 
-#include <unistd.h>
-
 #include "access/timeline.h"
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
 #include "access/xlogutils.h"
 #include "miscadmin.h"
-#include "pgstat.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/hsearch.h"
@@ -639,128 +636,6 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
 	forget_invalid_pages(rnode, forkNum, nblocks);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- * in timeline 'tli'.
- *
- * Will open, and keep open, one WAL segment stored in the static file
- * descriptor 'sendFile'. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- *
- * XXX This is very similar to pg_waldump's XLogDumpXLogRead and to XLogRead
- * in walsender.c but for small differences (such as lack of elog() in
- * frontend).  Probably these should be merged at some point.
- */
-static void
-XLogReadOld(char *buf, int segsize, TimeLineID tli, XLogRecPtr startptr,
-			Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	/* state maintained across calls */
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static TimeLineID sendTLI = 0;
-	static uint32 sendOff = 0;
-
-	Assert(segsize == wal_segment_size);
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segsize);
-
-		/* Do we need to switch to a different xlog segment? */
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, segsize) ||
-			sendTLI != tli)
-		{
-			char		path[MAXPGPATH];
-
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, segsize);
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-
-			sendFile = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-
-			if (sendFile < 0)
-			{
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									path)));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendOff = 0;
-			sendTLI = tli;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				char		path[MAXPGPATH];
-				int			save_errno = errno;
-
-				XLogFilePath(path, tli, sendSegNo, segsize);
-				errno = save_errno;
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								path, startoff)));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segsize - startoff))
-			segbytes = segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendFile, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes <= 0)
-		{
-			char		path[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-			errno = save_errno;
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %lu: %m",
-							path, sendOff, (unsigned long) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * Determine which timeline to read an xlog page from and set the
  * XLogReaderState's currTLI to that timeline ID.
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index a7b3e0ecbe..3ea05add53 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -251,8 +251,6 @@ static void WalSndSegmentOpen(XLogSegNo nextSegNo, TimeLineID *tli_p,
 							  int *file_p, WALOpenSegment *seg);
 
 
-static void XLogReadOld(char *buf, XLogRecPtr startptr, Size count);
-
 /* Initialize walsender process before entering the main command loop */
 void
 InitWalSender(void)
@@ -2358,191 +2356,6 @@ WalSndKill(int code, Datum arg)
 	SpinLockRelease(&walsnd->mutex);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- *
- * XXX probably this should be improved to suck data directly from the
- * WAL buffers when possible.
- *
- * Will open, and keep open, one WAL segment stored in the global file
- * descriptor sendFile. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- */
-static void
-XLogReadOld(char *buf, XLogRecPtr startptr, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-	XLogSegNo	segno;
-
-retry:
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, wal_segment_size);
-
-		if (sendSeg->file < 0 ||
-			!XLByteInSeg(recptr, sendSeg->num, sendSeg->size))
-		{
-			char		path[MAXPGPATH];
-
-			/* Switch to another logfile segment */
-			if (sendSeg->file >= 0)
-				close(sendSeg->file);
-
-			XLByteToSeg(recptr, sendSeg->num, sendSeg->size);
-
-			/*-------
-			 * When reading from a historic timeline, and there is a timeline
-			 * switch within this segment, read from the WAL segment belonging
-			 * to the new timeline.
-			 *
-			 * For example, imagine that this server is currently on timeline
-			 * 5, and we're streaming timeline 4. The switch from timeline 4
-			 * to 5 happened at 0/13002088. In pg_wal, we have these files:
-			 *
-			 * ...
-			 * 000000040000000000000012
-			 * 000000040000000000000013
-			 * 000000050000000000000013
-			 * 000000050000000000000014
-			 * ...
-			 *
-			 * In this situation, when requested to send the WAL from
-			 * segment 0x13, on timeline 4, we read the WAL from file
-			 * 000000050000000000000013. Archive recovery prefers files from
-			 * newer timelines, so if the segment was restored from the
-			 * archive on this server, the file belonging to the old timeline,
-			 * 000000040000000000000013, might not exist. Their contents are
-			 * equal up to the switchpoint, because at a timeline switch, the
-			 * used portion of the old segment is copied to the new file.
-			 *-------
-			 */
-			sendSeg->tli = sendTimeLine;
-			if (sendTimeLineIsHistoric)
-			{
-				XLogSegNo	endSegNo;
-
-				XLByteToSeg(sendTimeLineValidUpto, endSegNo, wal_segment_size);
-				if (sendSeg->num == endSegNo)
-					sendSeg->tli = sendTimeLineNextTLI;
-			}
-
-			XLogFilePath(path, sendSeg->tli, sendSeg->num, wal_segment_size);
-
-			sendSeg->file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-			if (sendSeg->file < 0)
-			{
-				/*
-				 * If the file is not found, assume it's because the standby
-				 * asked for a too old WAL segment that has already been
-				 * removed or recycled.
-				 */
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									XLogFileNameP(sendSeg->tli, sendSeg->num))));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendSeg->off = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendSeg->off != startoff)
-		{
-			if (lseek(sendSeg->file, (off_t) startoff, SEEK_SET) < 0)
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								XLogFileNameP(sendSeg->tli, sendSeg->num),
-								startoff)));
-			sendSeg->off = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (wal_segment_size - startoff))
-			segbytes = wal_segment_size - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendSeg->file, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes < 0)
-		{
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %zu: %m",
-							XLogFileNameP(sendSeg->tli, sendSeg->num),
-							sendSeg->off, (Size) segbytes)));
-		}
-		else if (readbytes == 0)
-		{
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg("could not read from log segment %s, offset %u: read %d of %zu",
-							XLogFileNameP(sendSeg->tli, sendSeg->num),
-							sendSeg->off, readbytes, (Size) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendSeg->off += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-
-	/*
-	 * After reading into the buffer, check that what we read was valid. We do
-	 * this after reading, because even though the segment was present when we
-	 * opened it, it might get recycled or removed while we read it. The
-	 * read() succeeds in that case, but the data we tried to read might
-	 * already have been overwritten with new WAL records.
-	 */
-	XLByteToSeg(startptr, segno, wal_segment_size);
-	CheckXLogRemoved(segno, ThisTimeLineID);
-
-	/*
-	 * During recovery, the currently-open WAL file might be replaced with the
-	 * file of the same name retrieved from archive. So we always need to
-	 * check what we read was valid after reading into the buffer. If it's
-	 * invalid, we try to open and read the file again.
-	 */
-	if (am_cascading_walsender)
-	{
-		WalSnd	   *walsnd = MyWalSnd;
-		bool		reload;
-
-		SpinLockAcquire(&walsnd->mutex);
-		reload = walsnd->needreload;
-		walsnd->needreload = false;
-		SpinLockRelease(&walsnd->mutex);
-
-		if (reload && sendSeg->file >= 0)
-		{
-			close(sendSeg->file);
-			sendSeg->file = -1;
-
-			goto retry;
-		}
-	}
-}
-
 /*
  * Callback for XLogRead() to open the next segment.
  */
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index cd5f589f03..1de8eb350e 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -14,7 +14,6 @@
 
 #include <dirent.h>
 #include <sys/stat.h>
-#include <unistd.h>
 
 #include "access/xlogreader.h"
 #include "access/xlogrecord.h"
@@ -341,128 +340,6 @@ WALDumpOpenSegment(XLogSegNo nextSegNo, TimeLineID *tli_p, int *file_p,
 	*file_p = file;
 }
 
-/*
- * Read count bytes from a segment file in the specified directory, for the
- * given timeline, containing the specified record pointer; store the data in
- * the passed buffer.
- */
-static void
-XLogDumpXLogRead(const char *directory, TimeLineID timeline_id,
-				 XLogRecPtr startptr, char *buf, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static uint32 sendOff = 0;
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, WalSegSz);
-
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, WalSegSz))
-		{
-			char		fname[MAXFNAMELEN];
-			int			tries;
-
-			/* Switch to another logfile segment */
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, WalSegSz);
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-			/*
-			 * In follow mode there is a short period of time after the server
-			 * has written the end of the previous file before the new file is
-			 * available. So we loop for 5 seconds looking for the file to
-			 * appear before giving up.
-			 */
-			for (tries = 0; tries < 10; tries++)
-			{
-				sendFile = open_file_in_directory(directory, fname);
-				if (sendFile >= 0)
-					break;
-				if (errno == ENOENT)
-				{
-					int			save_errno = errno;
-
-					/* File not there yet, try again */
-					pg_usleep(500 * 1000);
-
-					errno = save_errno;
-					continue;
-				}
-				/* Any other error, fall through and fail */
-				break;
-			}
-
-			if (sendFile < 0)
-				fatal_error("could not find file \"%s\": %s",
-							fname, strerror(errno));
-			sendOff = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				int			err = errno;
-				char		fname[MAXPGPATH];
-
-				XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-				fatal_error("could not seek in log file %s to offset %u: %s",
-							fname, startoff, strerror(err));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (WalSegSz - startoff))
-			segbytes = WalSegSz - startoff;
-		else
-			segbytes = nbytes;
-
-		readbytes = read(sendFile, p, segbytes);
-		if (readbytes <= 0)
-		{
-			int			err = errno;
-			char		fname[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-			errno = save_errno;
-
-			if (readbytes < 0)
-				fatal_error("could not read from log file %s, offset %u, length %d: %s",
-							fname, sendOff, segbytes, strerror(err));
-			else if (readbytes == 0)
-				fatal_error("could not read from log file %s, offset %u: read %d of %zu",
-							fname, sendOff, readbytes, (Size) segbytes);
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * XLogReader read_page callback
  */
-- 
2.20.1


--=-=-=--





^ permalink  raw  reply  [nested|flat] 9+ messages in thread

* [PATCH 2/2] Remove the old implemenations of XLogRead().
@ 2019-09-26 11:51  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 9+ messages in thread

From: Antonin Houska @ 2019-09-26 11:51 UTC (permalink / raw)

Done in a separate patch because the diff looks harder to read if one function
(XLogRead) is removed and another one (the WALSegmentOpen callback) is added
nearby at the same time (the addition and removal of code can get mixed in the
diff).
---
 src/backend/access/transam/xlogutils.c | 122 ----------------
 src/backend/replication/walsender.c    | 188 -------------------------
 src/bin/pg_waldump/pg_waldump.c        | 122 ----------------
 3 files changed, 432 deletions(-)

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 09d42d3112..002b8f72a9 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -639,128 +639,6 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
 	forget_invalid_pages(rnode, forkNum, nblocks);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- * in timeline 'tli'.
- *
- * Will open, and keep open, one WAL segment stored in the static file
- * descriptor 'sendFile'. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- *
- * XXX This is very similar to pg_waldump's XLogDumpXLogRead and to XLogRead
- * in walsender.c but for small differences (such as lack of elog() in
- * frontend).  Probably these should be merged at some point.
- */
-static void
-XLogReadOld(char *buf, int segsize, TimeLineID tli, XLogRecPtr startptr,
-			Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	/* state maintained across calls */
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static TimeLineID sendTLI = 0;
-	static uint32 sendOff = 0;
-
-	Assert(segsize == wal_segment_size);
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segsize);
-
-		/* Do we need to switch to a different xlog segment? */
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, segsize) ||
-			sendTLI != tli)
-		{
-			char		path[MAXPGPATH];
-
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, segsize);
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-
-			sendFile = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-
-			if (sendFile < 0)
-			{
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									path)));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendOff = 0;
-			sendTLI = tli;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				char		path[MAXPGPATH];
-				int			save_errno = errno;
-
-				XLogFilePath(path, tli, sendSegNo, segsize);
-				errno = save_errno;
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								path, startoff)));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segsize - startoff))
-			segbytes = segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendFile, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes <= 0)
-		{
-			char		path[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-			errno = save_errno;
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %lu: %m",
-							path, sendOff, (unsigned long) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * Determine which timeline to read an xlog page from and set the
  * XLogReaderState's currTLI to that timeline ID.
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index dcb84693fc..d7df72fb87 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -253,9 +253,6 @@ static void WalSndSegmentOpen(XLogSegNo nextSegNo, TimeLineID *tli_p,
 							  WALSegmentContext *segcxt);
 
 
-static void XLogReadOld(WALSegmentContext *segcxt, char *buf,
-						XLogRecPtr startptr, Size count);
-
 /* Initialize walsender process before entering the main command loop */
 void
 InitWalSender(void)
@@ -2375,191 +2372,6 @@ WalSndKill(int code, Datum arg)
 	SpinLockRelease(&walsnd->mutex);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- *
- * XXX probably this should be improved to suck data directly from the
- * WAL buffers when possible.
- *
- * Will open, and keep open, one WAL segment stored in the global file
- * descriptor sendFile. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- */
-static void
-XLogReadOld(WALSegmentContext *segcxt, char *buf, XLogRecPtr startptr, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-	XLogSegNo	segno;
-
-retry:
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segcxt->ws_segsize);
-
-		if (sendSeg->ws_file < 0 ||
-			!XLByteInSeg(recptr, sendSeg->ws_segno, segcxt->ws_segsize))
-		{
-			char		path[MAXPGPATH];
-
-			/* Switch to another logfile segment */
-			if (sendSeg->ws_file >= 0)
-				close(sendSeg->ws_file);
-
-			XLByteToSeg(recptr, sendSeg->ws_segno, segcxt->ws_segsize);
-
-			/*-------
-			 * When reading from a historic timeline, and there is a timeline
-			 * switch within this segment, read from the WAL segment belonging
-			 * to the new timeline.
-			 *
-			 * For example, imagine that this server is currently on timeline
-			 * 5, and we're streaming timeline 4. The switch from timeline 4
-			 * to 5 happened at 0/13002088. In pg_wal, we have these files:
-			 *
-			 * ...
-			 * 000000040000000000000012
-			 * 000000040000000000000013
-			 * 000000050000000000000013
-			 * 000000050000000000000014
-			 * ...
-			 *
-			 * In this situation, when requested to send the WAL from
-			 * segment 0x13, on timeline 4, we read the WAL from file
-			 * 000000050000000000000013. Archive recovery prefers files from
-			 * newer timelines, so if the segment was restored from the
-			 * archive on this server, the file belonging to the old timeline,
-			 * 000000040000000000000013, might not exist. Their contents are
-			 * equal up to the switchpoint, because at a timeline switch, the
-			 * used portion of the old segment is copied to the new file.
-			 *-------
-			 */
-			sendSeg->ws_tli = sendTimeLine;
-			if (sendTimeLineIsHistoric)
-			{
-				XLogSegNo	endSegNo;
-
-				XLByteToSeg(sendTimeLineValidUpto, endSegNo, segcxt->ws_segsize);
-				if (sendSeg->ws_segno == endSegNo)
-					sendSeg->ws_tli = sendTimeLineNextTLI;
-			}
-
-			XLogFilePath(path, sendSeg->ws_tli, sendSeg->ws_segno, segcxt->ws_segsize);
-
-			sendSeg->ws_file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-			if (sendSeg->ws_file < 0)
-			{
-				/*
-				 * If the file is not found, assume it's because the standby
-				 * asked for a too old WAL segment that has already been
-				 * removed or recycled.
-				 */
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno))));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendSeg->ws_off = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendSeg->ws_off != startoff)
-		{
-			if (lseek(sendSeg->ws_file, (off_t) startoff, SEEK_SET) < 0)
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-								startoff)));
-			sendSeg->ws_off = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segcxt->ws_segsize - startoff))
-			segbytes = segcxt->ws_segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendSeg->ws_file, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes < 0)
-		{
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %zu: %m",
-							XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-							sendSeg->ws_off, (Size) segbytes)));
-		}
-		else if (readbytes == 0)
-		{
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg("could not read from log segment %s, offset %u: read %d of %zu",
-							XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-							sendSeg->ws_off, readbytes, (Size) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendSeg->ws_off += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-
-	/*
-	 * After reading into the buffer, check that what we read was valid. We do
-	 * this after reading, because even though the segment was present when we
-	 * opened it, it might get recycled or removed while we read it. The
-	 * read() succeeds in that case, but the data we tried to read might
-	 * already have been overwritten with new WAL records.
-	 */
-	XLByteToSeg(startptr, segno, segcxt->ws_segsize);
-	CheckXLogRemoved(segno, ThisTimeLineID);
-
-	/*
-	 * During recovery, the currently-open WAL file might be replaced with the
-	 * file of the same name retrieved from archive. So we always need to
-	 * check what we read was valid after reading into the buffer. If it's
-	 * invalid, we try to open and read the file again.
-	 */
-	if (am_cascading_walsender)
-	{
-		WalSnd	   *walsnd = MyWalSnd;
-		bool		reload;
-
-		SpinLockAcquire(&walsnd->mutex);
-		reload = walsnd->needreload;
-		walsnd->needreload = false;
-		SpinLockRelease(&walsnd->mutex);
-
-		if (reload && sendSeg->ws_file >= 0)
-		{
-			close(sendSeg->ws_file);
-			sendSeg->ws_file = -1;
-
-			goto retry;
-		}
-	}
-}
-
 /*
  * Callback for XLogRead() to open the next segment.
  */
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index c97376101c..57dd7df56f 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -321,128 +321,6 @@ WALDumpOpenSegment(XLogSegNo nextSegNo, TimeLineID *tli_p, int *file_p,
 					fname, strerror(errno));
 }
 
-/*
- * Read count bytes from a segment file in the specified directory, for the
- * given timeline, containing the specified record pointer; store the data in
- * the passed buffer.
- */
-static void
-XLogDumpXLogRead(const char *directory, TimeLineID timeline_id,
-				 XLogRecPtr startptr, char *buf, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static uint32 sendOff = 0;
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, WalSegSz);
-
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, WalSegSz))
-		{
-			char		fname[MAXFNAMELEN];
-			int			tries;
-
-			/* Switch to another logfile segment */
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, WalSegSz);
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-			/*
-			 * In follow mode there is a short period of time after the server
-			 * has written the end of the previous file before the new file is
-			 * available. So we loop for 5 seconds looking for the file to
-			 * appear before giving up.
-			 */
-			for (tries = 0; tries < 10; tries++)
-			{
-				sendFile = open_file_in_directory(directory, fname);
-				if (sendFile >= 0)
-					break;
-				if (errno == ENOENT)
-				{
-					int			save_errno = errno;
-
-					/* File not there yet, try again */
-					pg_usleep(500 * 1000);
-
-					errno = save_errno;
-					continue;
-				}
-				/* Any other error, fall through and fail */
-				break;
-			}
-
-			if (sendFile < 0)
-				fatal_error("could not find file \"%s\": %s",
-							fname, strerror(errno));
-			sendOff = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				int			err = errno;
-				char		fname[MAXPGPATH];
-
-				XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-				fatal_error("could not seek in log file %s to offset %u: %s",
-							fname, startoff, strerror(err));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (WalSegSz - startoff))
-			segbytes = WalSegSz - startoff;
-		else
-			segbytes = nbytes;
-
-		readbytes = read(sendFile, p, segbytes);
-		if (readbytes <= 0)
-		{
-			int			err = errno;
-			char		fname[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-			errno = save_errno;
-
-			if (readbytes < 0)
-				fatal_error("could not read from log file %s, offset %u, length %d: %s",
-							fname, sendOff, segbytes, strerror(err));
-			else if (readbytes == 0)
-				fatal_error("could not read from log file %s, offset %u: read %d of %zu",
-							fname, sendOff, readbytes, (Size) segbytes);
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * XLogReader read_page callback
  */
-- 
2.20.1


--=-=-=--





^ permalink  raw  reply  [nested|flat] 9+ messages in thread

* [PATCH 2/2] Remove the old implemenations of XLogRead().
@ 2019-10-04 10:07  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 9+ messages in thread

From: Antonin Houska @ 2019-10-04 10:07 UTC (permalink / raw)

Done in a separate patch because the diff looks harder to read if one function
(XLogRead) is removed and another one (the WALSegmentOpen callback) is added
nearby at the same time (the addition and removal of code can get mixed in the
diff).
---
 src/backend/access/transam/xlogutils.c | 122 ----------------
 src/backend/replication/walsender.c    | 188 -------------------------
 src/bin/pg_waldump/pg_waldump.c        | 122 ----------------
 3 files changed, 432 deletions(-)

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 007974ea99..0211a68640 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -639,128 +639,6 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
 	forget_invalid_pages(rnode, forkNum, nblocks);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- * in timeline 'tli'.
- *
- * Will open, and keep open, one WAL segment stored in the static file
- * descriptor 'sendFile'. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- *
- * XXX This is very similar to pg_waldump's XLogDumpXLogRead and to XLogRead
- * in walsender.c but for small differences (such as lack of elog() in
- * frontend).  Probably these should be merged at some point.
- */
-static void
-XLogReadOld(char *buf, int segsize, TimeLineID tli, XLogRecPtr startptr,
-			Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	/* state maintained across calls */
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static TimeLineID sendTLI = 0;
-	static uint32 sendOff = 0;
-
-	Assert(segsize == wal_segment_size);
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segsize);
-
-		/* Do we need to switch to a different xlog segment? */
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, segsize) ||
-			sendTLI != tli)
-		{
-			char		path[MAXPGPATH];
-
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, segsize);
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-
-			sendFile = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-
-			if (sendFile < 0)
-			{
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									path)));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendOff = 0;
-			sendTLI = tli;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				char		path[MAXPGPATH];
-				int			save_errno = errno;
-
-				XLogFilePath(path, tli, sendSegNo, segsize);
-				errno = save_errno;
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								path, startoff)));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segsize - startoff))
-			segbytes = segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendFile, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes <= 0)
-		{
-			char		path[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-			errno = save_errno;
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %lu: %m",
-							path, sendOff, (unsigned long) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * Determine which timeline to read an xlog page from and set the
  * XLogReaderState's currTLI to that timeline ID.
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b21b143f99..76a5477389 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -252,9 +252,6 @@ static void WalSndSegmentOpen(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
 							  TimeLineID *tli_p, int *file_p);
 
 
-static void XLogReadOld(WALSegmentContext *segcxt, char *buf,
-						XLogRecPtr startptr, Size count);
-
 /* Initialize walsender process before entering the main command loop */
 void
 InitWalSender(void)
@@ -2377,191 +2374,6 @@ WalSndKill(int code, Datum arg)
 	SpinLockRelease(&walsnd->mutex);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- *
- * XXX probably this should be improved to suck data directly from the
- * WAL buffers when possible.
- *
- * Will open, and keep open, one WAL segment stored in the global file
- * descriptor sendFile. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- */
-static void
-XLogReadOld(WALSegmentContext *segcxt, char *buf, XLogRecPtr startptr, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-	XLogSegNo	segno;
-
-retry:
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segcxt->ws_segsize);
-
-		if (sendSeg->ws_file < 0 ||
-			!XLByteInSeg(recptr, sendSeg->ws_segno, segcxt->ws_segsize))
-		{
-			char		path[MAXPGPATH];
-
-			/* Switch to another logfile segment */
-			if (sendSeg->ws_file >= 0)
-				close(sendSeg->ws_file);
-
-			XLByteToSeg(recptr, sendSeg->ws_segno, segcxt->ws_segsize);
-
-			/*-------
-			 * When reading from a historic timeline, and there is a timeline
-			 * switch within this segment, read from the WAL segment belonging
-			 * to the new timeline.
-			 *
-			 * For example, imagine that this server is currently on timeline
-			 * 5, and we're streaming timeline 4. The switch from timeline 4
-			 * to 5 happened at 0/13002088. In pg_wal, we have these files:
-			 *
-			 * ...
-			 * 000000040000000000000012
-			 * 000000040000000000000013
-			 * 000000050000000000000013
-			 * 000000050000000000000014
-			 * ...
-			 *
-			 * In this situation, when requested to send the WAL from
-			 * segment 0x13, on timeline 4, we read the WAL from file
-			 * 000000050000000000000013. Archive recovery prefers files from
-			 * newer timelines, so if the segment was restored from the
-			 * archive on this server, the file belonging to the old timeline,
-			 * 000000040000000000000013, might not exist. Their contents are
-			 * equal up to the switchpoint, because at a timeline switch, the
-			 * used portion of the old segment is copied to the new file.
-			 *-------
-			 */
-			sendSeg->ws_tli = sendTimeLine;
-			if (sendTimeLineIsHistoric)
-			{
-				XLogSegNo	endSegNo;
-
-				XLByteToSeg(sendTimeLineValidUpto, endSegNo, segcxt->ws_segsize);
-				if (sendSeg->ws_segno == endSegNo)
-					sendSeg->ws_tli = sendTimeLineNextTLI;
-			}
-
-			XLogFilePath(path, sendSeg->ws_tli, sendSeg->ws_segno, segcxt->ws_segsize);
-
-			sendSeg->ws_file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-			if (sendSeg->ws_file < 0)
-			{
-				/*
-				 * If the file is not found, assume it's because the standby
-				 * asked for a too old WAL segment that has already been
-				 * removed or recycled.
-				 */
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno))));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendSeg->ws_off = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendSeg->ws_off != startoff)
-		{
-			if (lseek(sendSeg->ws_file, (off_t) startoff, SEEK_SET) < 0)
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-								startoff)));
-			sendSeg->ws_off = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segcxt->ws_segsize - startoff))
-			segbytes = segcxt->ws_segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendSeg->ws_file, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes < 0)
-		{
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %zu: %m",
-							XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-							sendSeg->ws_off, (Size) segbytes)));
-		}
-		else if (readbytes == 0)
-		{
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg("could not read from log segment %s, offset %u: read %d of %zu",
-							XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-							sendSeg->ws_off, readbytes, (Size) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendSeg->ws_off += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-
-	/*
-	 * After reading into the buffer, check that what we read was valid. We do
-	 * this after reading, because even though the segment was present when we
-	 * opened it, it might get recycled or removed while we read it. The
-	 * read() succeeds in that case, but the data we tried to read might
-	 * already have been overwritten with new WAL records.
-	 */
-	XLByteToSeg(startptr, segno, segcxt->ws_segsize);
-	CheckXLogRemoved(segno, ThisTimeLineID);
-
-	/*
-	 * During recovery, the currently-open WAL file might be replaced with the
-	 * file of the same name retrieved from archive. So we always need to
-	 * check what we read was valid after reading into the buffer. If it's
-	 * invalid, we try to open and read the file again.
-	 */
-	if (am_cascading_walsender)
-	{
-		WalSnd	   *walsnd = MyWalSnd;
-		bool		reload;
-
-		SpinLockAcquire(&walsnd->mutex);
-		reload = walsnd->needreload;
-		walsnd->needreload = false;
-		SpinLockRelease(&walsnd->mutex);
-
-		if (reload && sendSeg->ws_file >= 0)
-		{
-			close(sendSeg->ws_file);
-			sendSeg->ws_file = -1;
-
-			goto retry;
-		}
-	}
-}
-
 /*
  * Callback for XLogRead() to open the next segment.
  */
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index 4c49d1acf4..39686c235c 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -321,128 +321,6 @@ WALDumpOpenSegment(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
 					fname, strerror(errno));
 }
 
-/*
- * Read count bytes from a segment file in the specified directory, for the
- * given timeline, containing the specified record pointer; store the data in
- * the passed buffer.
- */
-static void
-XLogDumpXLogRead(const char *directory, TimeLineID timeline_id,
-				 XLogRecPtr startptr, char *buf, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static uint32 sendOff = 0;
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, WalSegSz);
-
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, WalSegSz))
-		{
-			char		fname[MAXFNAMELEN];
-			int			tries;
-
-			/* Switch to another logfile segment */
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, WalSegSz);
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-			/*
-			 * In follow mode there is a short period of time after the server
-			 * has written the end of the previous file before the new file is
-			 * available. So we loop for 5 seconds looking for the file to
-			 * appear before giving up.
-			 */
-			for (tries = 0; tries < 10; tries++)
-			{
-				sendFile = open_file_in_directory(directory, fname);
-				if (sendFile >= 0)
-					break;
-				if (errno == ENOENT)
-				{
-					int			save_errno = errno;
-
-					/* File not there yet, try again */
-					pg_usleep(500 * 1000);
-
-					errno = save_errno;
-					continue;
-				}
-				/* Any other error, fall through and fail */
-				break;
-			}
-
-			if (sendFile < 0)
-				fatal_error("could not find file \"%s\": %s",
-							fname, strerror(errno));
-			sendOff = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				int			err = errno;
-				char		fname[MAXPGPATH];
-
-				XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-				fatal_error("could not seek in log file %s to offset %u: %s",
-							fname, startoff, strerror(err));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (WalSegSz - startoff))
-			segbytes = WalSegSz - startoff;
-		else
-			segbytes = nbytes;
-
-		readbytes = read(sendFile, p, segbytes);
-		if (readbytes <= 0)
-		{
-			int			err = errno;
-			char		fname[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-			errno = save_errno;
-
-			if (readbytes < 0)
-				fatal_error("could not read from log file %s, offset %u, length %d: %s",
-							fname, sendOff, segbytes, strerror(err));
-			else if (readbytes == 0)
-				fatal_error("could not read from log file %s, offset %u: read %d of %zu",
-							fname, sendOff, readbytes, (Size) segbytes);
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * XLogReader read_page callback
  */
-- 
2.20.1


--=-=-=--





^ permalink  raw  reply  [nested|flat] 9+ messages in thread

* [PATCH 2/2] Remove the old implemenations of XLogRead().
@ 2019-10-11 10:07  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 9+ messages in thread

From: Antonin Houska @ 2019-10-11 10:07 UTC (permalink / raw)

Done in a separate patch because the diff looks harder to read if one function
(XLogRead) is removed and another one (the WALSegmentOpen callback) is added
nearby at the same time (the addition and removal of code can get mixed in the
diff).
---
 src/backend/access/transam/xlogutils.c | 122 ----------------
 src/backend/replication/walsender.c    | 188 -------------------------
 src/bin/pg_waldump/pg_waldump.c        | 122 ----------------
 3 files changed, 432 deletions(-)

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 007974ea99..0211a68640 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -639,128 +639,6 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
 	forget_invalid_pages(rnode, forkNum, nblocks);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- * in timeline 'tli'.
- *
- * Will open, and keep open, one WAL segment stored in the static file
- * descriptor 'sendFile'. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- *
- * XXX This is very similar to pg_waldump's XLogDumpXLogRead and to XLogRead
- * in walsender.c but for small differences (such as lack of elog() in
- * frontend).  Probably these should be merged at some point.
- */
-static void
-XLogReadOld(char *buf, int segsize, TimeLineID tli, XLogRecPtr startptr,
-			Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	/* state maintained across calls */
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static TimeLineID sendTLI = 0;
-	static uint32 sendOff = 0;
-
-	Assert(segsize == wal_segment_size);
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segsize);
-
-		/* Do we need to switch to a different xlog segment? */
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, segsize) ||
-			sendTLI != tli)
-		{
-			char		path[MAXPGPATH];
-
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, segsize);
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-
-			sendFile = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-
-			if (sendFile < 0)
-			{
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									path)));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendOff = 0;
-			sendTLI = tli;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				char		path[MAXPGPATH];
-				int			save_errno = errno;
-
-				XLogFilePath(path, tli, sendSegNo, segsize);
-				errno = save_errno;
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								path, startoff)));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segsize - startoff))
-			segbytes = segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendFile, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes <= 0)
-		{
-			char		path[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-			errno = save_errno;
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %lu: %m",
-							path, sendOff, (unsigned long) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * Determine which timeline to read an xlog page from and set the
  * XLogReaderState's currTLI to that timeline ID.
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b21b143f99..76a5477389 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -252,9 +252,6 @@ static void WalSndSegmentOpen(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
 							  TimeLineID *tli_p, int *file_p);
 
 
-static void XLogReadOld(WALSegmentContext *segcxt, char *buf,
-						XLogRecPtr startptr, Size count);
-
 /* Initialize walsender process before entering the main command loop */
 void
 InitWalSender(void)
@@ -2377,191 +2374,6 @@ WalSndKill(int code, Datum arg)
 	SpinLockRelease(&walsnd->mutex);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- *
- * XXX probably this should be improved to suck data directly from the
- * WAL buffers when possible.
- *
- * Will open, and keep open, one WAL segment stored in the global file
- * descriptor sendFile. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- */
-static void
-XLogReadOld(WALSegmentContext *segcxt, char *buf, XLogRecPtr startptr, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-	XLogSegNo	segno;
-
-retry:
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segcxt->ws_segsize);
-
-		if (sendSeg->ws_file < 0 ||
-			!XLByteInSeg(recptr, sendSeg->ws_segno, segcxt->ws_segsize))
-		{
-			char		path[MAXPGPATH];
-
-			/* Switch to another logfile segment */
-			if (sendSeg->ws_file >= 0)
-				close(sendSeg->ws_file);
-
-			XLByteToSeg(recptr, sendSeg->ws_segno, segcxt->ws_segsize);
-
-			/*-------
-			 * When reading from a historic timeline, and there is a timeline
-			 * switch within this segment, read from the WAL segment belonging
-			 * to the new timeline.
-			 *
-			 * For example, imagine that this server is currently on timeline
-			 * 5, and we're streaming timeline 4. The switch from timeline 4
-			 * to 5 happened at 0/13002088. In pg_wal, we have these files:
-			 *
-			 * ...
-			 * 000000040000000000000012
-			 * 000000040000000000000013
-			 * 000000050000000000000013
-			 * 000000050000000000000014
-			 * ...
-			 *
-			 * In this situation, when requested to send the WAL from
-			 * segment 0x13, on timeline 4, we read the WAL from file
-			 * 000000050000000000000013. Archive recovery prefers files from
-			 * newer timelines, so if the segment was restored from the
-			 * archive on this server, the file belonging to the old timeline,
-			 * 000000040000000000000013, might not exist. Their contents are
-			 * equal up to the switchpoint, because at a timeline switch, the
-			 * used portion of the old segment is copied to the new file.
-			 *-------
-			 */
-			sendSeg->ws_tli = sendTimeLine;
-			if (sendTimeLineIsHistoric)
-			{
-				XLogSegNo	endSegNo;
-
-				XLByteToSeg(sendTimeLineValidUpto, endSegNo, segcxt->ws_segsize);
-				if (sendSeg->ws_segno == endSegNo)
-					sendSeg->ws_tli = sendTimeLineNextTLI;
-			}
-
-			XLogFilePath(path, sendSeg->ws_tli, sendSeg->ws_segno, segcxt->ws_segsize);
-
-			sendSeg->ws_file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-			if (sendSeg->ws_file < 0)
-			{
-				/*
-				 * If the file is not found, assume it's because the standby
-				 * asked for a too old WAL segment that has already been
-				 * removed or recycled.
-				 */
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno))));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendSeg->ws_off = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendSeg->ws_off != startoff)
-		{
-			if (lseek(sendSeg->ws_file, (off_t) startoff, SEEK_SET) < 0)
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-								startoff)));
-			sendSeg->ws_off = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segcxt->ws_segsize - startoff))
-			segbytes = segcxt->ws_segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendSeg->ws_file, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes < 0)
-		{
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %zu: %m",
-							XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-							sendSeg->ws_off, (Size) segbytes)));
-		}
-		else if (readbytes == 0)
-		{
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg("could not read from log segment %s, offset %u: read %d of %zu",
-							XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-							sendSeg->ws_off, readbytes, (Size) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendSeg->ws_off += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-
-	/*
-	 * After reading into the buffer, check that what we read was valid. We do
-	 * this after reading, because even though the segment was present when we
-	 * opened it, it might get recycled or removed while we read it. The
-	 * read() succeeds in that case, but the data we tried to read might
-	 * already have been overwritten with new WAL records.
-	 */
-	XLByteToSeg(startptr, segno, segcxt->ws_segsize);
-	CheckXLogRemoved(segno, ThisTimeLineID);
-
-	/*
-	 * During recovery, the currently-open WAL file might be replaced with the
-	 * file of the same name retrieved from archive. So we always need to
-	 * check what we read was valid after reading into the buffer. If it's
-	 * invalid, we try to open and read the file again.
-	 */
-	if (am_cascading_walsender)
-	{
-		WalSnd	   *walsnd = MyWalSnd;
-		bool		reload;
-
-		SpinLockAcquire(&walsnd->mutex);
-		reload = walsnd->needreload;
-		walsnd->needreload = false;
-		SpinLockRelease(&walsnd->mutex);
-
-		if (reload && sendSeg->ws_file >= 0)
-		{
-			close(sendSeg->ws_file);
-			sendSeg->ws_file = -1;
-
-			goto retry;
-		}
-	}
-}
-
 /*
  * Callback for XLogRead() to open the next segment.
  */
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index 4c49d1acf4..39686c235c 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -321,128 +321,6 @@ WALDumpOpenSegment(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
 					fname, strerror(errno));
 }
 
-/*
- * Read count bytes from a segment file in the specified directory, for the
- * given timeline, containing the specified record pointer; store the data in
- * the passed buffer.
- */
-static void
-XLogDumpXLogRead(const char *directory, TimeLineID timeline_id,
-				 XLogRecPtr startptr, char *buf, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static uint32 sendOff = 0;
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, WalSegSz);
-
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, WalSegSz))
-		{
-			char		fname[MAXFNAMELEN];
-			int			tries;
-
-			/* Switch to another logfile segment */
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, WalSegSz);
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-			/*
-			 * In follow mode there is a short period of time after the server
-			 * has written the end of the previous file before the new file is
-			 * available. So we loop for 5 seconds looking for the file to
-			 * appear before giving up.
-			 */
-			for (tries = 0; tries < 10; tries++)
-			{
-				sendFile = open_file_in_directory(directory, fname);
-				if (sendFile >= 0)
-					break;
-				if (errno == ENOENT)
-				{
-					int			save_errno = errno;
-
-					/* File not there yet, try again */
-					pg_usleep(500 * 1000);
-
-					errno = save_errno;
-					continue;
-				}
-				/* Any other error, fall through and fail */
-				break;
-			}
-
-			if (sendFile < 0)
-				fatal_error("could not find file \"%s\": %s",
-							fname, strerror(errno));
-			sendOff = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				int			err = errno;
-				char		fname[MAXPGPATH];
-
-				XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-				fatal_error("could not seek in log file %s to offset %u: %s",
-							fname, startoff, strerror(err));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (WalSegSz - startoff))
-			segbytes = WalSegSz - startoff;
-		else
-			segbytes = nbytes;
-
-		readbytes = read(sendFile, p, segbytes);
-		if (readbytes <= 0)
-		{
-			int			err = errno;
-			char		fname[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-			errno = save_errno;
-
-			if (readbytes < 0)
-				fatal_error("could not read from log file %s, offset %u, length %d: %s",
-							fname, sendOff, segbytes, strerror(err));
-			else if (readbytes == 0)
-				fatal_error("could not read from log file %s, offset %u: read %d of %zu",
-							fname, sendOff, readbytes, (Size) segbytes);
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * XLogReader read_page callback
  */
-- 
2.20.1


--=-=-=--





^ permalink  raw  reply  [nested|flat] 9+ messages in thread

* [PATCH 2/2] Remove the old implemenations of XLogRead().
@ 2019-11-12 10:51  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 9+ messages in thread

From: Antonin Houska @ 2019-11-12 10:51 UTC (permalink / raw)

Done in a separate patch because the diff looks harder to read if one function
(XLogRead) is removed and another one (the WALSegmentOpen callback) is added
nearby at the same time (the addition and removal of code can get mixed in the
diff).
---
 src/backend/access/transam/xlogutils.c | 122 ----------------
 src/backend/replication/walsender.c    | 188 -------------------------
 src/bin/pg_waldump/pg_waldump.c        | 122 ----------------
 3 files changed, 432 deletions(-)

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 18e436f4fd..98118f484e 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -639,128 +639,6 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
 	forget_invalid_pages(rnode, forkNum, nblocks);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- * in timeline 'tli'.
- *
- * Will open, and keep open, one WAL segment stored in the static file
- * descriptor 'sendFile'. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- *
- * XXX This is very similar to pg_waldump's XLogDumpXLogRead and to XLogRead
- * in walsender.c but for small differences (such as lack of elog() in
- * frontend).  Probably these should be merged at some point.
- */
-static void
-XLogReadOld(char *buf, int segsize, TimeLineID tli, XLogRecPtr startptr,
-			Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	/* state maintained across calls */
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static TimeLineID sendTLI = 0;
-	static uint32 sendOff = 0;
-
-	Assert(segsize == wal_segment_size);
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segsize);
-
-		/* Do we need to switch to a different xlog segment? */
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, segsize) ||
-			sendTLI != tli)
-		{
-			char		path[MAXPGPATH];
-
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, segsize);
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-
-			sendFile = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-
-			if (sendFile < 0)
-			{
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									path)));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendOff = 0;
-			sendTLI = tli;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				char		path[MAXPGPATH];
-				int			save_errno = errno;
-
-				XLogFilePath(path, tli, sendSegNo, segsize);
-				errno = save_errno;
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								path, startoff)));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segsize - startoff))
-			segbytes = segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendFile, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes <= 0)
-		{
-			char		path[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-			errno = save_errno;
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %lu: %m",
-							path, sendOff, (unsigned long) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * Determine which timeline to read an xlog page from and set the
  * XLogReaderState's currTLI to that timeline ID.
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 92a539aa5c..80ef5eb909 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -252,9 +252,6 @@ static void WalSndSegmentOpen(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
 							  TimeLineID *tli_p, int *file_p);
 
 
-static void XLogReadOld(WALSegmentContext *segcxt, char *buf,
-						XLogRecPtr startptr, Size count);
-
 /* Initialize walsender process before entering the main command loop */
 void
 InitWalSender(void)
@@ -2376,191 +2373,6 @@ WalSndKill(int code, Datum arg)
 	SpinLockRelease(&walsnd->mutex);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- *
- * XXX probably this should be improved to suck data directly from the
- * WAL buffers when possible.
- *
- * Will open, and keep open, one WAL segment stored in the global file
- * descriptor sendFile. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- */
-static void
-XLogReadOld(WALSegmentContext *segcxt, char *buf, XLogRecPtr startptr, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-	XLogSegNo	segno;
-
-retry:
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segcxt->ws_segsize);
-
-		if (sendSeg->ws_file < 0 ||
-			!XLByteInSeg(recptr, sendSeg->ws_segno, segcxt->ws_segsize))
-		{
-			char		path[MAXPGPATH];
-
-			/* Switch to another logfile segment */
-			if (sendSeg->ws_file >= 0)
-				close(sendSeg->ws_file);
-
-			XLByteToSeg(recptr, sendSeg->ws_segno, segcxt->ws_segsize);
-
-			/*-------
-			 * When reading from a historic timeline, and there is a timeline
-			 * switch within this segment, read from the WAL segment belonging
-			 * to the new timeline.
-			 *
-			 * For example, imagine that this server is currently on timeline
-			 * 5, and we're streaming timeline 4. The switch from timeline 4
-			 * to 5 happened at 0/13002088. In pg_wal, we have these files:
-			 *
-			 * ...
-			 * 000000040000000000000012
-			 * 000000040000000000000013
-			 * 000000050000000000000013
-			 * 000000050000000000000014
-			 * ...
-			 *
-			 * In this situation, when requested to send the WAL from
-			 * segment 0x13, on timeline 4, we read the WAL from file
-			 * 000000050000000000000013. Archive recovery prefers files from
-			 * newer timelines, so if the segment was restored from the
-			 * archive on this server, the file belonging to the old timeline,
-			 * 000000040000000000000013, might not exist. Their contents are
-			 * equal up to the switchpoint, because at a timeline switch, the
-			 * used portion of the old segment is copied to the new file.
-			 *-------
-			 */
-			sendSeg->ws_tli = sendTimeLine;
-			if (sendTimeLineIsHistoric)
-			{
-				XLogSegNo	endSegNo;
-
-				XLByteToSeg(sendTimeLineValidUpto, endSegNo, segcxt->ws_segsize);
-				if (sendSeg->ws_segno == endSegNo)
-					sendSeg->ws_tli = sendTimeLineNextTLI;
-			}
-
-			XLogFilePath(path, sendSeg->ws_tli, sendSeg->ws_segno, segcxt->ws_segsize);
-
-			sendSeg->ws_file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-			if (sendSeg->ws_file < 0)
-			{
-				/*
-				 * If the file is not found, assume it's because the standby
-				 * asked for a too old WAL segment that has already been
-				 * removed or recycled.
-				 */
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno))));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendSeg->ws_off = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendSeg->ws_off != startoff)
-		{
-			if (lseek(sendSeg->ws_file, (off_t) startoff, SEEK_SET) < 0)
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-								startoff)));
-			sendSeg->ws_off = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segcxt->ws_segsize - startoff))
-			segbytes = segcxt->ws_segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendSeg->ws_file, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes < 0)
-		{
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %zu: %m",
-							XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-							sendSeg->ws_off, (Size) segbytes)));
-		}
-		else if (readbytes == 0)
-		{
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg("could not read from log segment %s, offset %u: read %d of %zu",
-							XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-							sendSeg->ws_off, readbytes, (Size) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendSeg->ws_off += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-
-	/*
-	 * After reading into the buffer, check that what we read was valid. We do
-	 * this after reading, because even though the segment was present when we
-	 * opened it, it might get recycled or removed while we read it. The
-	 * read() succeeds in that case, but the data we tried to read might
-	 * already have been overwritten with new WAL records.
-	 */
-	XLByteToSeg(startptr, segno, segcxt->ws_segsize);
-	CheckXLogRemoved(segno, ThisTimeLineID);
-
-	/*
-	 * During recovery, the currently-open WAL file might be replaced with the
-	 * file of the same name retrieved from archive. So we always need to
-	 * check what we read was valid after reading into the buffer. If it's
-	 * invalid, we try to open and read the file again.
-	 */
-	if (am_cascading_walsender)
-	{
-		WalSnd	   *walsnd = MyWalSnd;
-		bool		reload;
-
-		SpinLockAcquire(&walsnd->mutex);
-		reload = walsnd->needreload;
-		walsnd->needreload = false;
-		SpinLockRelease(&walsnd->mutex);
-
-		if (reload && sendSeg->ws_file >= 0)
-		{
-			close(sendSeg->ws_file);
-			sendSeg->ws_file = -1;
-
-			goto retry;
-		}
-	}
-}
-
 /*
  * Callback for XLogRead() to open the next segment.
  */
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index c0c2590d56..f1908a8868 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -320,128 +320,6 @@ WALDumpOpenSegment(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
 					fname, strerror(errno));
 }
 
-/*
- * Read count bytes from a segment file in the specified directory, for the
- * given timeline, containing the specified record pointer; store the data in
- * the passed buffer.
- */
-static void
-XLogDumpXLogRead(const char *directory, TimeLineID timeline_id,
-				 XLogRecPtr startptr, char *buf, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static uint32 sendOff = 0;
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, WalSegSz);
-
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, WalSegSz))
-		{
-			char		fname[MAXFNAMELEN];
-			int			tries;
-
-			/* Switch to another logfile segment */
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, WalSegSz);
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-			/*
-			 * In follow mode there is a short period of time after the server
-			 * has written the end of the previous file before the new file is
-			 * available. So we loop for 5 seconds looking for the file to
-			 * appear before giving up.
-			 */
-			for (tries = 0; tries < 10; tries++)
-			{
-				sendFile = open_file_in_directory(directory, fname);
-				if (sendFile >= 0)
-					break;
-				if (errno == ENOENT)
-				{
-					int			save_errno = errno;
-
-					/* File not there yet, try again */
-					pg_usleep(500 * 1000);
-
-					errno = save_errno;
-					continue;
-				}
-				/* Any other error, fall through and fail */
-				break;
-			}
-
-			if (sendFile < 0)
-				fatal_error("could not find file \"%s\": %s",
-							fname, strerror(errno));
-			sendOff = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				int			err = errno;
-				char		fname[MAXPGPATH];
-
-				XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-
-				fatal_error("could not seek in log file %s to offset %u: %s",
-							fname, startoff, strerror(err));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (WalSegSz - startoff))
-			segbytes = WalSegSz - startoff;
-		else
-			segbytes = nbytes;
-
-		readbytes = read(sendFile, p, segbytes);
-		if (readbytes <= 0)
-		{
-			int			err = errno;
-			char		fname[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFileName(fname, timeline_id, sendSegNo, WalSegSz);
-			errno = save_errno;
-
-			if (readbytes < 0)
-				fatal_error("could not read from log file %s, offset %u, length %d: %s",
-							fname, sendOff, segbytes, strerror(err));
-			else if (readbytes == 0)
-				fatal_error("could not read from log file %s, offset %u: read %d of %zu",
-							fname, sendOff, readbytes, (Size) segbytes);
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * XLogReader read_page callback
  */
-- 
2.20.1


--=-=-=--





^ permalink  raw  reply  [nested|flat] 9+ messages in thread

* [PATCH 2/2] Remove the old implemenations of XLogRead().
@ 2019-11-20 14:11  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 9+ messages in thread

From: Antonin Houska @ 2019-11-20 14:11 UTC (permalink / raw)

Done in a separate patch because the diff looks harder to read if one function
(XLogRead) is removed and another one (the WALSegmentOpen callback) is added
nearby at the same time (the addition and removal of code can get mixed in the
diff).
---
 src/backend/access/transam/xlogutils.c | 122 ----------------
 src/backend/replication/walsender.c    | 188 -------------------------
 2 files changed, 310 deletions(-)

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index baca17260c..a16d47f156 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -639,128 +639,6 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
 	forget_invalid_pages(rnode, forkNum, nblocks);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- * in timeline 'tli'.
- *
- * Will open, and keep open, one WAL segment stored in the static file
- * descriptor 'sendFile'. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- *
- * XXX This is very similar to pg_waldump's XLogDumpXLogRead and to XLogRead
- * in walsender.c but for small differences (such as lack of elog() in
- * frontend).  Probably these should be merged at some point.
- */
-static void
-XLogReadOld(char *buf, int segsize, TimeLineID tli, XLogRecPtr startptr,
-			Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-
-	/* state maintained across calls */
-	static int	sendFile = -1;
-	static XLogSegNo sendSegNo = 0;
-	static TimeLineID sendTLI = 0;
-	static uint32 sendOff = 0;
-
-	Assert(segsize == wal_segment_size);
-
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segsize);
-
-		/* Do we need to switch to a different xlog segment? */
-		if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo, segsize) ||
-			sendTLI != tli)
-		{
-			char		path[MAXPGPATH];
-
-			if (sendFile >= 0)
-				close(sendFile);
-
-			XLByteToSeg(recptr, sendSegNo, segsize);
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-
-			sendFile = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-
-			if (sendFile < 0)
-			{
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									path)));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendOff = 0;
-			sendTLI = tli;
-		}
-
-		/* Need to seek in the file? */
-		if (sendOff != startoff)
-		{
-			if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
-			{
-				char		path[MAXPGPATH];
-				int			save_errno = errno;
-
-				XLogFilePath(path, tli, sendSegNo, segsize);
-				errno = save_errno;
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								path, startoff)));
-			}
-			sendOff = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segsize - startoff))
-			segbytes = segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendFile, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes <= 0)
-		{
-			char		path[MAXPGPATH];
-			int			save_errno = errno;
-
-			XLogFilePath(path, tli, sendSegNo, segsize);
-			errno = save_errno;
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %lu: %m",
-							path, sendOff, (unsigned long) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendOff += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-}
-
 /*
  * Determine which timeline to read an xlog page from and set the
  * XLogReaderState's currTLI to that timeline ID.
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 11611072b0..d2426b0960 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -252,9 +252,6 @@ static int	WalSndSegmentOpen(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
 							  TimeLineID *tli_p);
 
 
-static void XLogReadOld(WALSegmentContext *segcxt, char *buf,
-						XLogRecPtr startptr, Size count);
-
 /* Initialize walsender process before entering the main command loop */
 void
 InitWalSender(void)
@@ -2376,191 +2373,6 @@ WalSndKill(int code, Datum arg)
 	SpinLockRelease(&walsnd->mutex);
 }
 
-/*
- * Read 'count' bytes from WAL into 'buf', starting at location 'startptr'
- *
- * XXX probably this should be improved to suck data directly from the
- * WAL buffers when possible.
- *
- * Will open, and keep open, one WAL segment stored in the global file
- * descriptor sendFile. This means if XLogRead is used once, there will
- * always be one descriptor left open until the process ends, but never
- * more than one.
- */
-static void
-XLogReadOld(WALSegmentContext *segcxt, char *buf, XLogRecPtr startptr, Size count)
-{
-	char	   *p;
-	XLogRecPtr	recptr;
-	Size		nbytes;
-	XLogSegNo	segno;
-
-retry:
-	p = buf;
-	recptr = startptr;
-	nbytes = count;
-
-	while (nbytes > 0)
-	{
-		uint32		startoff;
-		int			segbytes;
-		int			readbytes;
-
-		startoff = XLogSegmentOffset(recptr, segcxt->ws_segsize);
-
-		if (sendSeg->ws_file < 0 ||
-			!XLByteInSeg(recptr, sendSeg->ws_segno, segcxt->ws_segsize))
-		{
-			char		path[MAXPGPATH];
-
-			/* Switch to another logfile segment */
-			if (sendSeg->ws_file >= 0)
-				close(sendSeg->ws_file);
-
-			XLByteToSeg(recptr, sendSeg->ws_segno, segcxt->ws_segsize);
-
-			/*-------
-			 * When reading from a historic timeline, and there is a timeline
-			 * switch within this segment, read from the WAL segment belonging
-			 * to the new timeline.
-			 *
-			 * For example, imagine that this server is currently on timeline
-			 * 5, and we're streaming timeline 4. The switch from timeline 4
-			 * to 5 happened at 0/13002088. In pg_wal, we have these files:
-			 *
-			 * ...
-			 * 000000040000000000000012
-			 * 000000040000000000000013
-			 * 000000050000000000000013
-			 * 000000050000000000000014
-			 * ...
-			 *
-			 * In this situation, when requested to send the WAL from
-			 * segment 0x13, on timeline 4, we read the WAL from file
-			 * 000000050000000000000013. Archive recovery prefers files from
-			 * newer timelines, so if the segment was restored from the
-			 * archive on this server, the file belonging to the old timeline,
-			 * 000000040000000000000013, might not exist. Their contents are
-			 * equal up to the switchpoint, because at a timeline switch, the
-			 * used portion of the old segment is copied to the new file.
-			 *-------
-			 */
-			sendSeg->ws_tli = sendTimeLine;
-			if (sendTimeLineIsHistoric)
-			{
-				XLogSegNo	endSegNo;
-
-				XLByteToSeg(sendTimeLineValidUpto, endSegNo, segcxt->ws_segsize);
-				if (sendSeg->ws_segno == endSegNo)
-					sendSeg->ws_tli = sendTimeLineNextTLI;
-			}
-
-			XLogFilePath(path, sendSeg->ws_tli, sendSeg->ws_segno, segcxt->ws_segsize);
-
-			sendSeg->ws_file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
-			if (sendSeg->ws_file < 0)
-			{
-				/*
-				 * If the file is not found, assume it's because the standby
-				 * asked for a too old WAL segment that has already been
-				 * removed or recycled.
-				 */
-				if (errno == ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("requested WAL segment %s has already been removed",
-									XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno))));
-				else
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not open file \"%s\": %m",
-									path)));
-			}
-			sendSeg->ws_off = 0;
-		}
-
-		/* Need to seek in the file? */
-		if (sendSeg->ws_off != startoff)
-		{
-			if (lseek(sendSeg->ws_file, (off_t) startoff, SEEK_SET) < 0)
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not seek in log segment %s to offset %u: %m",
-								XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-								startoff)));
-			sendSeg->ws_off = startoff;
-		}
-
-		/* How many bytes are within this segment? */
-		if (nbytes > (segcxt->ws_segsize - startoff))
-			segbytes = segcxt->ws_segsize - startoff;
-		else
-			segbytes = nbytes;
-
-		pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
-		readbytes = read(sendSeg->ws_file, p, segbytes);
-		pgstat_report_wait_end();
-		if (readbytes < 0)
-		{
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read from log segment %s, offset %u, length %zu: %m",
-							XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-							sendSeg->ws_off, (Size) segbytes)));
-		}
-		else if (readbytes == 0)
-		{
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg("could not read from log segment %s, offset %u: read %d of %zu",
-							XLogFileNameP(sendSeg->ws_tli, sendSeg->ws_segno),
-							sendSeg->ws_off, readbytes, (Size) segbytes)));
-		}
-
-		/* Update state for read */
-		recptr += readbytes;
-
-		sendSeg->ws_off += readbytes;
-		nbytes -= readbytes;
-		p += readbytes;
-	}
-
-	/*
-	 * After reading into the buffer, check that what we read was valid. We do
-	 * this after reading, because even though the segment was present when we
-	 * opened it, it might get recycled or removed while we read it. The
-	 * read() succeeds in that case, but the data we tried to read might
-	 * already have been overwritten with new WAL records.
-	 */
-	XLByteToSeg(startptr, segno, segcxt->ws_segsize);
-	CheckXLogRemoved(segno, ThisTimeLineID);
-
-	/*
-	 * During recovery, the currently-open WAL file might be replaced with the
-	 * file of the same name retrieved from archive. So we always need to
-	 * check what we read was valid after reading into the buffer. If it's
-	 * invalid, we try to open and read the file again.
-	 */
-	if (am_cascading_walsender)
-	{
-		WalSnd	   *walsnd = MyWalSnd;
-		bool		reload;
-
-		SpinLockAcquire(&walsnd->mutex);
-		reload = walsnd->needreload;
-		walsnd->needreload = false;
-		SpinLockRelease(&walsnd->mutex);
-
-		if (reload && sendSeg->ws_file >= 0)
-		{
-			close(sendSeg->ws_file);
-			sendSeg->ws_file = -1;
-
-			goto retry;
-		}
-	}
-}
-
 /*
  * Callback for XLogRead() to open the next segment.
  */
-- 
2.20.1


--=-=-=--





^ permalink  raw  reply  [nested|flat] 9+ messages in thread

* [PATCH v2 5/7] Row pattern recognition patch (docs).
@ 2023-06-26 08:05  Tatsuo Ishii <[email protected]>
  0 siblings, 0 replies; 9+ messages in thread

From: Tatsuo Ishii @ 2023-06-26 08:05 UTC (permalink / raw)

---
 doc/src/sgml/advanced.sgml   | 52 +++++++++++++++++++++++++++
 doc/src/sgml/func.sgml       | 69 ++++++++++++++++++++++++++++++++++++
 doc/src/sgml/ref/select.sgml | 29 +++++++++++++--
 3 files changed, 148 insertions(+), 2 deletions(-)

diff --git a/doc/src/sgml/advanced.sgml b/doc/src/sgml/advanced.sgml
index 755c9f1485..e9bbd5bc7c 100644
--- a/doc/src/sgml/advanced.sgml
+++ b/doc/src/sgml/advanced.sgml
@@ -537,6 +537,58 @@ WHERE pos &lt; 3;
     <literal>rank</literal> less than 3.
    </para>
 
+   <para>
+    Window function <function>rpr</function> can be used with row pattern
+    common syntax to perform row pattern recognition in a query. Row pattern
+    common syntax includes two sub clauses. <literal>DEFINE</literal> defines
+    definition variables along with an expression. The expression must be a
+    logical expression, which means it must
+    return <literal>TRUE</literal>, <literal>FALSE</literal>
+    or <literal>NULL</literal>. Moreover if the expression comprises a column
+    reference, it must be the argument of <function>rpr</function>. An
+    example of <literal>DEFINE</literal> is as follows.
+
+<programlisting>
+DEFINE
+ LOWPRICE AS price &lt;= 100,
+ UP AS price &gt; PREV(price),
+ DOWN AS price &lt; PREV(price)
+</programlisting>
+
+    Note that <function>PREV</function> returns price column in the previous
+    row if it's called in a context of row pattern recognition. So in the
+    second line means the definition variable "UP" is <literal>TRUE</literal>
+    when price column in the current row is greater than the price column in
+    the previous row. Likewise, "DOWN" is <literal>TRUE</literal> when when
+    price column in the current row is lower than the price column in the
+    previous row.
+   </para>
+   <para>
+    Once <literal>DEFINE</literal> exists, <literal>PATTERN</literal> can be
+    used. <literal>PATTERN</literal> defines a sequence of rows that satisfies
+    certain conditions.  For example following <literal>PATTERN</literal>
+    defines that a row starts with the condition "LOWPRICE", then one or more
+    rows satisfy "UP" and finally one or more rows satisfy "DOWN". If a
+    sequence of rows found, rpr returns the column at the starting row.
+    Example of a <literal>SELECT</literal> using the <literal>DEFINE</literal>
+    and <literal>PATTERN</literal> clause is as follows.
+
+<programlisting>    
+SELECT company, tdate, price, rpr(price) OVER w FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP PAST LAST ROW
+ INITIAL
+ PATTERN (LOWPRICE UP+ DOWN+)
+ DEFINE
+  LOWPRICE AS price &lt;= 100,
+  UP AS price &gt; PREV(price),
+  DOWN AS price &lt; PREV(price)
+);
+</programlisting>
+   </para>
+
    <para>
     When a query involves multiple window functions, it is possible to write
     out each one with a separate <literal>OVER</literal> clause, but this is
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 5a47ce4343..8069c58ca5 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -21648,6 +21648,22 @@ SELECT count(*) FROM sometable;
         returns <literal>NULL</literal> if there is no such row.
        </para></entry>
       </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>rpr</primary>
+        </indexterm>
+        <function>rpr</function> ( <parameter>value</parameter> <type>anyelement</type> )
+        <returnvalue>anyelement</returnvalue>
+       </para>
+       <para>
+        Perform row pattern recognition using column specified
+        by <parameter>value</parameter> and returns the value of the column if
+        current row is the first matching row;
+        returns <literal>NULL</literal> otherwise.
+       </para></entry>
+      </row>
      </tbody>
     </tgroup>
    </table>
@@ -21687,6 +21703,59 @@ SELECT count(*) FROM sometable;
    Other frame specifications can be used to obtain other effects.
   </para>
 
+  <para>
+   Row pattern recognition navigation functions are listed in
+   <xref linkend="functions-rpr-navigation-table"/>.  These functions
+   can be used to describe DEFINE clause of Row pattern recognition.
+  </para>
+
+   <table id="functions-rpr-navigation-table">
+    <title>Row Pattern Navigation Functions</title>
+    <tgroup cols="1">
+     <thead>
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        Function
+       </para>
+       <para>
+        Description
+       </para></entry>
+      </row>
+     </thead>
+
+     <tbody>
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>prev</primary>
+        </indexterm>
+        <function>prev</function> ( <parameter>value</parameter> <type>anyelement</type> )
+        <returnvalue>anyelement</returnvalue>
+       </para>
+       <para>
+        Returns the column value at the previous row;
+        returns NULL if there is no previous row in the window frame.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>next</primary>
+        </indexterm>
+        <function>next</function> ( <parameter>value</parameter> <type>anyelement</type> )
+        <returnvalue>anyelement</returnvalue>
+       </para>
+       <para>
+        Returns the column value at the next row;
+        returns NULL if there is no next row in the window frame.
+       </para></entry>
+      </row>
+
+     </tbody>
+    </tgroup>
+   </table>
+
   <note>
    <para>
     The SQL standard defines a <literal>RESPECT NULLS</literal> or
diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index 0ee0cc7e64..16478a3950 100644
--- a/doc/src/sgml/ref/select.sgml
+++ b/doc/src/sgml/ref/select.sgml
@@ -966,8 +966,8 @@ WINDOW <replaceable class="parameter">window_name</replaceable> AS ( <replaceabl
     The <replaceable class="parameter">frame_clause</replaceable> can be one of
 
 <synopsis>
-{ RANGE | ROWS | GROUPS } <replaceable>frame_start</replaceable> [ <replaceable>frame_exclusion</replaceable> ]
-{ RANGE | ROWS | GROUPS } BETWEEN <replaceable>frame_start</replaceable> AND <replaceable>frame_end</replaceable> [ <replaceable>frame_exclusion</replaceable> ]
+{ RANGE | ROWS | GROUPS } <replaceable>frame_start</replaceable> [ <replaceable>frame_exclusion</replaceable> ] [row_pattern_common_syntax]
+{ RANGE | ROWS | GROUPS } BETWEEN <replaceable>frame_start</replaceable> AND <replaceable>frame_end</replaceable> [ <replaceable>frame_exclusion</replaceable> ] [row_pattern_common_syntax]
 </synopsis>
 
     where <replaceable>frame_start</replaceable>
@@ -1074,6 +1074,31 @@ EXCLUDE NO OTHERS
     a given peer group will be in the frame or excluded from it.
    </para>
 
+   <para>
+    The
+    optional <replaceable class="parameter">row_pattern_common_syntax</replaceable>
+    defines the <firstterm>row pattern recognition condition</firstterm> for
+    this
+    window. <replaceable class="parameter">row_pattern_common_syntax</replaceable>
+    includes following subclauses. <literal>AFTER MATCH SKIP PAST LAST
+    ROW</literal> or <literal>AFTER MATCH SKIP TO NEXT ROW</literal> controls
+    how to proceed to next row position after a match
+    found. With <literal>AFTER MATCH SKIP PAST LAST ROW</literal> (the
+    default) next row position is next to the last row of previous match. On
+    the other hand, with <literal>AFTER MATCH SKIP TO NEXT ROW</literal> next
+    row position is always next to the last row of previous
+    match. <literal>DEFINE</literal> defines definition variables along with a
+    boolean expression. <literal>PATTERN</literal> defines a sequence of rows
+    that satisfies certain conditions using variables defined
+    in <literal>DEFINE</literal> clause.
+
+<synopsis>
+[ AFTER MATCH SKIP PAST LAST ROW | AFTER MATCH SKIP TO NEXT ROW ]
+PATTERN <replaceable class="parameter">pattern_variable_name</replaceable>[+] [, ...]
+DEFINE <replaceable class="parameter">definition_varible_name</replaceable> AS <replaceable class="parameter">expression</replaceable> [, ...]
+</synopsis>    
+   </para>
+
    <para>
     The purpose of a <literal>WINDOW</literal> clause is to specify the
     behavior of <firstterm>window functions</firstterm> appearing in the query's
-- 
2.25.1


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 filename="v2-0006-Row-pattern-recognition-patch-tests.patch"



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-- links below jump to the message on this page --
2019-07-09 09:54 [PATCH 5/5] Remove the old implemenations of XLogRead(). Antonin Houska <[email protected]>
2019-09-09 09:53 [PATCH 4/4] Remove the old implemenations of XLogRead(). Antonin Houska <[email protected]>
2019-09-23 05:40 [PATCH 6/6] Remove the old implemenations of XLogRead(). Antonin Houska <[email protected]>
2019-09-26 11:51 [PATCH 2/2] Remove the old implemenations of XLogRead(). Antonin Houska <[email protected]>
2019-10-04 10:07 [PATCH 2/2] Remove the old implemenations of XLogRead(). Antonin Houska <[email protected]>
2019-10-11 10:07 [PATCH 2/2] Remove the old implemenations of XLogRead(). Antonin Houska <[email protected]>
2019-11-12 10:51 [PATCH 2/2] Remove the old implemenations of XLogRead(). Antonin Houska <[email protected]>
2019-11-20 14:11 [PATCH 2/2] Remove the old implemenations of XLogRead(). Antonin Houska <[email protected]>
2023-06-26 08:05 [PATCH v2 5/7] Row pattern recognition patch (docs). Tatsuo Ishii <[email protected]>

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