Restructure local-buffer handling per recent pghackers discussion.

The local buffer manager is no longer used for newly-created relations
(unless they are TEMP); a new non-TEMP relation goes through the shared
bufmgr and thus will participate normally in checkpoints.  But TEMP relations
use the local buffer manager throughout their lifespan.  Also, operations
in TEMP relations are not logged in WAL, thus improving performance.
Since it's no longer necessary to fsync relations as they move out of the
local buffers into shared buffers, quite a lot of smgr.c/md.c/fd.c code
is no longer needed and has been removed: there's no concept of a dirty
relation anymore in md.c/fd.c, and we never fsync anything but WAL.
Still TODO: improve local buffer management algorithms so that it would
be reasonable to increase NLocBuffer.

1 files changed, 16 insertions, 150 deletions

diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index 978d85d4868..25051a9799c 100644
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/smgr/md.c,v 1.91 2002/06/20 20:29:35 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/smgr/md.c,v 1.92 2002/08/06 02:36:34 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -381,16 +381,7 @@ mdclose_fd(int fd)
 
 		/* if not closed already */
 		if (v->mdfd_vfd >= 0)
-		{
-			/*
-			 * We sync the file descriptor so that we don't need to reopen
-			 * it at transaction commit to force changes to disk.  (This
-			 * is not really optional, because we are about to forget that
-			 * the file even exists...)
-			 */
-			FileSync(v->mdfd_vfd);
 			FileClose(v->mdfd_vfd);
-		}
 		/* Now free vector */
 		v = v->mdfd_chain;
 		if (ov != &Md_fdvec[fd])
@@ -403,16 +394,7 @@ mdclose_fd(int fd)
 	if (v != (MdfdVec *) NULL)
 	{
 		if (v->mdfd_vfd >= 0)
-		{
-			/*
-			 * We sync the file descriptor so that we don't need to reopen
-			 * it at transaction commit to force changes to disk.  (This
-			 * is not really optional, because we are about to forget that
-			 * the file even exists...)
-			 */
-			FileSync(v->mdfd_vfd);
 			FileClose(v->mdfd_vfd);
-		}
 	}
 #endif
 
@@ -498,55 +480,15 @@ mdwrite(Relation reln, BlockNumber blocknum, char *buffer)
 }
 
 /*
- *	mdflush() -- Synchronously write a block to disk.
- *
- *		This is exactly like mdwrite(), but doesn't return until the file
- *		system buffer cache has been flushed.
- */
-int
-mdflush(Relation reln, BlockNumber blocknum, char *buffer)
-{
-	int			status;
-	long		seekpos;
-	MdfdVec    *v;
-
-	v = _mdfd_getseg(reln, blocknum);
-
-#ifndef LET_OS_MANAGE_FILESIZE
-	seekpos = (long) (BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE)));
-#ifdef DIAGNOSTIC
-	if (seekpos >= BLCKSZ * RELSEG_SIZE)
-		elog(FATAL, "seekpos too big!");
-#endif
-#else
-	seekpos = (long) (BLCKSZ * (blocknum));
-#endif
-
-	if (FileSeek(v->mdfd_vfd, seekpos, SEEK_SET) != seekpos)
-		return SM_FAIL;
-
-	/* write and sync the block */
-	status = SM_SUCCESS;
-	if (FileWrite(v->mdfd_vfd, buffer, BLCKSZ) != BLCKSZ
-		|| FileSync(v->mdfd_vfd) < 0)
-		status = SM_FAIL;
-
-	return status;
-}
-
-/*
  *	mdblindwrt() -- Write a block to disk blind.
  *
- *		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 much like mdwrite().  If dofsync is TRUE, then we fsync
- *		the file, making it more like mdflush().
+ *		We have to be able to do this using only the rnode of the relation
+ *		in which the block belongs.  Otherwise this is much like mdwrite().
  */
 int
 mdblindwrt(RelFileNode rnode,
 		   BlockNumber blkno,
-		   char *buffer,
-		   bool dofsync)
+		   char *buffer)
 {
 	int			status;
 	long		seekpos;
@@ -568,7 +510,6 @@ mdblindwrt(RelFileNode rnode,
 #endif
 
 	errno = 0;
-
 	if (lseek(fd, seekpos, SEEK_SET) != seekpos)
 	{
 		elog(LOG, "mdblindwrt: lseek(%ld) failed: %m", seekpos);
@@ -578,7 +519,7 @@ mdblindwrt(RelFileNode rnode,
 
 	status = SM_SUCCESS;
 
-	/* write and optionally sync the block */
+	/* write the block */
 	errno = 0;
 	if (write(fd, buffer, BLCKSZ) != BLCKSZ)
 	{
@@ -599,54 +540,6 @@ mdblindwrt(RelFileNode rnode,
 }
 
 /*
- *	mdmarkdirty() -- Mark the specified block "dirty" (ie, needs fsync).
- *
- *		Returns SM_SUCCESS or SM_FAIL.
- */
-int
-mdmarkdirty(Relation reln, BlockNumber blkno)
-{
-	MdfdVec    *v;
-
-	v = _mdfd_getseg(reln, blkno);
-
-	FileMarkDirty(v->mdfd_vfd);
-
-	return SM_SUCCESS;
-}
-
-/*
- *	mdblindmarkdirty() -- Mark the specified block "dirty" (ie, needs fsync).
- *
- *		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 much like mdmarkdirty().  However, we do the fsync immediately
- *		rather than building md/fd datastructures to postpone it till later.
- */
-int
-mdblindmarkdirty(RelFileNode rnode,
-				 BlockNumber blkno)
-{
-	int			status;
-	int			fd;
-
-	fd = _mdfd_blind_getseg(rnode, blkno);
-
-	if (fd < 0)
-		return SM_FAIL;
-
-	status = SM_SUCCESS;
-
-	if (pg_fsync(fd) < 0)
-		status = SM_FAIL;
-
-	if (close(fd) < 0)
-		status = SM_FAIL;
-
-	return status;
-}
-
-/*
  *	mdnblocks() -- Get the number of blocks stored in a relation.
  *
  *		Important side effect: all segments of the relation are opened
@@ -796,61 +689,36 @@ mdtruncate(Relation reln, BlockNumber nblocks)
 /*
  *	mdcommit() -- Commit a transaction.
  *
- *		All changes to magnetic disk relations must be forced to stable
- *		storage.  This routine makes a pass over the private table of
- *		file descriptors.  Any descriptors to which we have done writes,
- *		but not synced, are synced here.
- *
  *		Returns SM_SUCCESS or SM_FAIL with errno set as appropriate.
  */
 int
-mdcommit()
+mdcommit(void)
 {
-	int			i;
-	MdfdVec    *v;
-
-	for (i = 0; i < CurFd; i++)
-	{
-		v = &Md_fdvec[i];
-		if (v->mdfd_flags & MDFD_FREE)
-			continue;
-		/* Sync the file entry */
-#ifndef LET_OS_MANAGE_FILESIZE
-		for (; v != (MdfdVec *) NULL; v = v->mdfd_chain)
-#else
-		if (v != (MdfdVec *) NULL)
-#endif
-		{
-			if (FileSync(v->mdfd_vfd) < 0)
-				return SM_FAIL;
-		}
-	}
-
+	/*
+	 * We don't actually have to do anything here...
+	 */
 	return SM_SUCCESS;
 }
 
 /*
  *	mdabort() -- Abort a transaction.
  *
- *		Changes need not be forced to disk at transaction abort.  We mark
- *		all file descriptors as clean here.  Always returns SM_SUCCESS.
+ *		Changes need not be forced to disk at transaction abort.
  */
 int
-mdabort()
+mdabort(void)
 {
 	/*
-	 * We don't actually have to do anything here.  fd.c will discard
-	 * fsync-needed bits in its AtEOXact_Files() routine.
+	 * We don't actually have to do anything here...
 	 */
 	return SM_SUCCESS;
 }
 
 /*
- *	mdsync() -- Sync storage.
- *
+ *	mdsync() -- Sync previous writes to stable storage.
  */
 int
-mdsync()
+mdsync(void)
 {
 	sync();
 	if (IsUnderPostmaster)
@@ -861,11 +729,9 @@ mdsync()
 
 /*
  *	_fdvec_alloc () -- grab a free (or new) md file descriptor vector.
- *
  */
-static
-int
-_fdvec_alloc()
+static int
+_fdvec_alloc(void)
 {
 	MdfdVec    *nvec;
 	int			fdvec,