Tweak smgrblindwrt per advice from Vadim: add parameter indicating

whether to do fsync or not, and if so (which should be seldom) just
do the fsync immediately.  This way we need not build data structures
in md.c/fd.c for blind writes.

Author: tglsfdc

src/backend/storage/buffer/bufmgr.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.78 2000/04/09 04:43:18 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.79 2000/04/10 23:41:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1127,7 +1127,8 @@ BufferSync()
 											  bufHdr->blind.relname,
 											  bufdb, bufrel,
 											  bufHdr->tag.blockNum,
-											  (char *) MAKE_PTR(bufHdr->data));
+											  (char *) MAKE_PTR(bufHdr->data),
+											  true); /* must fsync */
 					}
 					else
 					{
@@ -1529,7 +1530,8 @@ BufferReplace(BufferDesc *bufHdr)
 		status = smgrblindwrt(DEFAULT_SMGR, bufHdr->blind.dbname,
 							  bufHdr->blind.relname, bufdb, bufrel,
 							  bufHdr->tag.blockNum,
-							  (char *) MAKE_PTR(bufHdr->data));
+							  (char *) MAKE_PTR(bufHdr->data),
+							  false); /* no fsync */
 	}
 
 #ifndef OPTIMIZE_SINGLE
@@ -1544,9 +1546,11 @@ BufferReplace(BufferDesc *bufHdr)
 		return FALSE;
 
 	/* If we had marked this buffer as needing to be fsync'd, we can forget
-	 * about that, because it's now the storage manager's responsibility.
+	 * about that, because it's now the storage manager's responsibility
+	 * (but only if we called smgrwrite, not smgrblindwrt).
 	 */
-	ClearBufferDirtiedByMe(BufferDescriptorGetBuffer(bufHdr), bufHdr);
+	if (reln != (Relation) NULL)
+		ClearBufferDirtiedByMe(BufferDescriptorGetBuffer(bufHdr), bufHdr);
 
 	BufferFlushCount++;
 

src/backend/storage/smgr/md.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/smgr/md.c,v 1.65 2000/04/09 04:43:20 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/smgr/md.c,v 1.66 2000/04/10 23:41:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -48,11 +48,10 @@
 typedef struct _MdfdVec
 {
 	int			mdfd_vfd;		/* fd number in vfd pool */
-	int			mdfd_flags;		/* free, temporary */
+	int			mdfd_flags;		/* fd status flags */
 
 /* these are the assigned bits in mdfd_flags: */
 #define MDFD_FREE		(1 << 0)/* unused entry */
-#define MDFD_TEMP		(1 << 1)/* close this entry at transaction end */
 
 	int			mdfd_lstbcnt;	/* most recent block count */
 	int			mdfd_nextFree;	/* next free vector */
@@ -72,8 +71,8 @@ static void mdclose_fd(int fd);
 static int _mdfd_getrelnfd(Relation reln);
 static MdfdVec *_mdfd_openseg(Relation reln, int segno, int oflags);
 static MdfdVec *_mdfd_getseg(Relation reln, int blkno);
-static MdfdVec *_mdfd_blind_getseg(char *dbname, char *relname,
-								   Oid dbid, Oid relid, int blkno);
+static int _mdfd_blind_getseg(char *dbname, char *relname,
+							  Oid dbid, Oid relid, int blkno);
 static int	_fdvec_alloc(void);
 static void _fdvec_free(int);
 static BlockNumber _mdnblocks(File file, Size blcksz);
@@ -572,23 +571,25 @@ mdflush(Relation reln, BlockNumber blocknum, char *buffer)
  *
  *		We have to be able to do this using only the name and OID of
  *		the database and relation in which the block belongs.  Otherwise
- *		this is just like mdwrite().
+ *		this is much like mdwrite().  If dofsync is TRUE, then we fsync
+ *		the file, making it more like mdflush().
  */
 int
 mdblindwrt(char *dbname,
 		   char *relname,
 		   Oid dbid,
 		   Oid relid,
 		   BlockNumber blkno,
-		   char *buffer)
+		   char *buffer,
+		   bool dofsync)
 {
 	int			status;
 	long		seekpos;
-	MdfdVec    *v;
+	int			fd;
 
-	v = _mdfd_blind_getseg(dbname, relname, dbid, relid, blkno);
+	fd = _mdfd_blind_getseg(dbname, relname, dbid, relid, blkno);
 
-	if (v == NULL)
+	if (fd < 0)
 		return SM_FAIL;
 
 #ifndef LET_OS_MANAGE_FILESIZE
@@ -601,11 +602,22 @@ mdblindwrt(char *dbname,
 	seekpos = (long) (BLCKSZ * (blkno));
 #endif
 
-	if (FileSeek(v->mdfd_vfd, seekpos, SEEK_SET) != seekpos)
+	if (lseek(fd, seekpos, SEEK_SET) != seekpos)
+	{
+		close(fd);
 		return SM_FAIL;
+	}
 
 	status = SM_SUCCESS;
-	if (FileWrite(v->mdfd_vfd, buffer, BLCKSZ) != BLCKSZ)
+
+	/* write and optionally sync the block */
+	if (write(fd, buffer, BLCKSZ) != BLCKSZ)
+		status = SM_FAIL;
+	else if (dofsync &&
+			 pg_fsync(fd) < 0)
+		status = SM_FAIL;
+
+	if (close(fd) < 0)
 		status = SM_FAIL;
 
 	return status;
@@ -633,7 +645,8 @@ mdmarkdirty(Relation reln, BlockNumber blkno)
  *
  *		We have to be able to do this using only the name and OID of
  *		the database and relation in which the block belongs.  Otherwise
- *		this is just like mdmarkdirty().
+ *		this is much like mdmarkdirty().  However, we do the fsync immediately
+ *		rather than building md/fd datastructures to postpone it till later.
  */
 int
 mdblindmarkdirty(char *dbname,
@@ -642,16 +655,23 @@ mdblindmarkdirty(char *dbname,
 				 Oid relid,
 				 BlockNumber blkno)
 {
-	MdfdVec    *v;
+	int			status;
+	int			fd;
 
-	v = _mdfd_blind_getseg(dbname, relname, dbid, relid, blkno);
+	fd = _mdfd_blind_getseg(dbname, relname, dbid, relid, blkno);
 
-	if (v == NULL)
+	if (fd < 0)
 		return SM_FAIL;
 
-	FileMarkDirty(v->mdfd_vfd);
+	status = SM_SUCCESS;
 
-	return SM_SUCCESS;
+	if (pg_fsync(fd) < 0)
+		status = SM_FAIL;
+
+	if (close(fd) < 0)
+		status = SM_FAIL;
+
+	return status;
 }
 
 /*
@@ -820,24 +840,15 @@ mdcommit()
 		v = &Md_fdvec[i];
 		if (v->mdfd_flags & MDFD_FREE)
 			continue;
-		if (v->mdfd_flags & MDFD_TEMP)
-		{
-			/* Sync and close the file */
-			mdclose_fd(i);
-		}
-		else
-		{
-			/* Sync, but keep the file entry */
-
+		/* Sync the file entry */
 #ifndef LET_OS_MANAGE_FILESIZE
-			for ( ; v != (MdfdVec *) NULL; v = v->mdfd_chain)
+		for ( ; v != (MdfdVec *) NULL; v = v->mdfd_chain)
 #else
-			if (v != (MdfdVec *) NULL)
+		if (v != (MdfdVec *) NULL)
 #endif
-			{
-				if (FileSync(v->mdfd_vfd) < 0)
-					return SM_FAIL;
-			}
+		{
+			if (FileSync(v->mdfd_vfd) < 0)
+				return SM_FAIL;
 		}
 	}
 
@@ -854,21 +865,9 @@ mdcommit()
 int
 mdabort()
 {
-	int			i;
-	MdfdVec    *v;
-
-	for (i = 0; i < CurFd; i++)
-	{
-		v = &Md_fdvec[i];
-		if (v->mdfd_flags & MDFD_FREE)
-			continue;
-		if (v->mdfd_flags & MDFD_TEMP)
-		{
-			/* Close the file */
-			mdclose_fd(i);
-		}
-	}
-
+	/* We don't actually have to do anything here.  fd.c will discard
+	 * fsync-needed bits in its AtEOXact_Files() routine.
+	 */
 	return SM_SUCCESS;
 }
 
@@ -1057,102 +1056,52 @@ _mdfd_getseg(Relation reln, int blkno)
 	return v;
 }
 
-/* Find the segment of the relation holding the specified block.
- * This is the same as _mdfd_getseg() except that we must work
- * "blind" with no Relation struct.
+/*
+ * Find the segment of the relation holding the specified block.
  *
- * NOTE: we have no easy way to tell whether a FD already exists for the
- * target relation, so we always make a new one.  This should probably
- * be improved somehow, but I doubt it's a significant performance issue
- * under normal circumstances.  The FD is marked to be closed at end of xact
- * so that we don't accumulate a lot of dead FDs.
+ * This performs the same work as _mdfd_getseg() except that we must work
+ * "blind" with no Relation struct.  We assume that we are not likely to
+ * touch the same relation again soon, so we do not create an FD entry for
+ * the relation --- we just open a kernel file descriptor which will be
+ * used and promptly closed.  The return value is the kernel descriptor,
+ * or -1 on failure.
  */
 
-static MdfdVec *
+static int
 _mdfd_blind_getseg(char *dbname, char *relname, Oid dbid, Oid relid,
 				   int blkno)
 {
-	MdfdVec    *v;
 	char	   *path;
 	int			fd;
-	int			vfd;
 #ifndef LET_OS_MANAGE_FILESIZE
 	int			segno;
-	int			targsegno;
 #endif
 
-	/* construct the path to the file and open it */
+	/* construct the path to the relation */
 	path = relpath_blind(dbname, relname, dbid, relid);
 
-#ifndef __CYGWIN32__
-	fd = FileNameOpenFile(path, O_RDWR, 0600);
-#else
-	fd = FileNameOpenFile(path, O_RDWR | O_BINARY, 0600);
-#endif
-
-	if (fd < 0)
-		return NULL;
-
-	vfd = _fdvec_alloc();
-	if (vfd < 0)
-		return NULL;
-
-	Md_fdvec[vfd].mdfd_vfd = fd;
-	Md_fdvec[vfd].mdfd_flags = MDFD_TEMP;
-	Md_fdvec[vfd].mdfd_lstbcnt = _mdnblocks(fd, BLCKSZ);
 #ifndef LET_OS_MANAGE_FILESIZE
-	Md_fdvec[vfd].mdfd_chain = (MdfdVec *) NULL;
-
-#ifdef DIAGNOSTIC
-	if (Md_fdvec[vfd].mdfd_lstbcnt > RELSEG_SIZE)
-		elog(FATAL, "segment too big on relopen!");
-#endif
-
-	targsegno = blkno / RELSEG_SIZE;
-	for (v = &Md_fdvec[vfd], segno = 1; segno <= targsegno; segno++)
+	/* append the '.segno', if needed */
+	segno = blkno / RELSEG_SIZE;
+	if (segno > 0)
 	{
-		char	   *segpath;
-		MdfdVec    *newv;
-		MemoryContext oldcxt;
+		char   *segpath = (char *) palloc(strlen(path) + 12);
 
-		segpath = (char *) palloc(strlen(path) + 12);
 		sprintf(segpath, "%s.%d", path, segno);
-
-#ifndef __CYGWIN32__
-		fd = FileNameOpenFile(segpath, O_RDWR | O_CREAT, 0600);
-#else
-		fd = FileNameOpenFile(segpath, O_RDWR | O_BINARY | O_CREAT, 0600);
+		pfree(path);
+		path = segpath;
+	}
 #endif
 
-		pfree(segpath);
-
-		if (fd < 0)
-			return (MdfdVec *) NULL;
-
-		/* allocate an mdfdvec entry for it */
-		oldcxt = MemoryContextSwitchTo(MdCxt);
-		newv = (MdfdVec *) palloc(sizeof(MdfdVec));
-		MemoryContextSwitchTo(oldcxt);
-
-		/* fill the entry */
-		newv->mdfd_vfd = fd;
-		newv->mdfd_flags = MDFD_TEMP;
-		newv->mdfd_lstbcnt = _mdnblocks(fd, BLCKSZ);
-		newv->mdfd_chain = (MdfdVec *) NULL;
-#ifdef DIAGNOSTIC
-		if (newv->mdfd_lstbcnt > RELSEG_SIZE)
-			elog(FATAL, "segment too big on open!");
-#endif
-		v->mdfd_chain = newv;
-		v = newv;
-	}
+#ifndef __CYGWIN32__
+	fd = open(path, O_RDWR, 0600);
 #else
-	v = &Md_fdvec[vfd];
+	fd = open(path, O_RDWR | O_BINARY, 0600);
 #endif
 
 	pfree(path);
 
-	return v;
+	return fd;
 }
 
 static BlockNumber

src/backend/storage/smgr/mm.c

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/smgr/Attic/mm.c,v 1.18 2000/01/26 05:57:05 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/smgr/Attic/mm.c,v 1.19 2000/04/10 23:41:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -478,7 +478,8 @@ mmblindwrt(char *dbstr,
 		   Oid dbid,
 		   Oid relid,
 		   BlockNumber blkno,
-		   char *buffer)
+		   char *buffer,
+		   bool dofsync)
 {
 	return SM_FAIL;
 }