Clean up WAL/buffer interactions as per my recent proposal. Get rid of the

misleadingly-named WriteBuffer routine, and instead require routines that
change buffer pages to call MarkBufferDirty (which does exactly what it says).
We also require that they do so before calling XLogInsert; this takes care of
the synchronization requirement documented in SyncOneBuffer.  Note that
because bufmgr takes the buffer content lock (in shared mode) while writing
out any buffer, it doesn't matter whether MarkBufferDirty is executed before
the buffer content change is complete, so long as the content change is
completed before releasing exclusive lock on the buffer.  So it's OK to set
the dirtybit before we fill in the LSN.
This eliminates the former kluge of needing to set the dirtybit in LockBuffer.
Aside from making the code more transparent, we can also add some new
debugging assertions, in particular that the caller of MarkBufferDirty must
hold the buffer content lock, not merely a pin.

1 files changed, 32 insertions, 38 deletions

diff --git a/src/backend/access/nbtree/nbtxlog.c b/src/backend/access/nbtree/nbtxlog.c
index 2047f37529..b8d33f5ae1 100644
--- a/src/backend/access/nbtree/nbtxlog.c
+++ b/src/backend/access/nbtree/nbtxlog.c
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/nbtree/nbtxlog.c,v 1.29 2006/03/29 21:17:37 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/nbtree/nbtxlog.c,v 1.30 2006/03/31 23:32:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -69,8 +69,7 @@ forget_matching_split(Relation reln, RelFileNode node,
 	itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum));
 	rightblk = ItemPointerGetBlockNumber(&(itup->t_tid));
 	Assert(ItemPointerGetOffsetNumber(&(itup->t_tid)) == P_HIKEY);
-	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-	ReleaseBuffer(buffer);
+	UnlockReleaseBuffer(buffer);
 
 	foreach(l, incomplete_splits)
 	{
@@ -80,7 +79,8 @@ forget_matching_split(Relation reln, RelFileNode node,
 			rightblk == split->rightblk)
 		{
 			if (is_root != split->is_root)
-				elog(LOG, "forget_matching_split: fishy is_root data");
+				elog(LOG, "forget_matching_split: fishy is_root data (expected %d, got %d)",
+					 split->is_root, is_root);
 			incomplete_splits = list_delete_ptr(incomplete_splits, split);
 			break;				/* need not look further */
 		}
@@ -143,8 +143,8 @@ _bt_restore_meta(Relation reln, XLogRecPtr lsn,
 
 	PageSetLSN(metapg, lsn);
 	PageSetTLI(metapg, ThisTimeLineID);
-	LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
-	WriteBuffer(metabuf);
+	MarkBufferDirty(metabuf);
+	UnlockReleaseBuffer(metabuf);
 }
 
 static void
@@ -185,8 +185,7 @@ btree_xlog_insert(bool isleaf, bool ismeta,
 
 			if (XLByteLE(lsn, PageGetLSN(page)))
 			{
-				LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-				ReleaseBuffer(buffer);
+				UnlockReleaseBuffer(buffer);
 			}
 			else
 			{
@@ -197,8 +196,8 @@ btree_xlog_insert(bool isleaf, bool ismeta,
 
 				PageSetLSN(page, lsn);
 				PageSetTLI(page, ThisTimeLineID);
-				LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-				WriteBuffer(buffer);
+				MarkBufferDirty(buffer);
+				UnlockReleaseBuffer(buffer);
 			}
 		}
 	}
@@ -255,8 +254,8 @@ btree_xlog_split(bool onleft, bool isroot,
 
 	PageSetLSN(page, lsn);
 	PageSetTLI(page, ThisTimeLineID);
-	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-	WriteBuffer(buffer);
+	MarkBufferDirty(buffer);
+	UnlockReleaseBuffer(buffer);
 
 	/* Right (new) sibling */
 	buffer = XLogReadBuffer(reln, rightsib, true);
@@ -277,8 +276,8 @@ btree_xlog_split(bool onleft, bool isroot,
 
 	PageSetLSN(page, lsn);
 	PageSetTLI(page, ThisTimeLineID);
-	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-	WriteBuffer(buffer);
+	MarkBufferDirty(buffer);
+	UnlockReleaseBuffer(buffer);
 
 	/* Fix left-link of right (next) page */
 	if (!(record->xl_info & XLR_BKP_BLOCK_1))
@@ -292,8 +291,7 @@ btree_xlog_split(bool onleft, bool isroot,
 
 				if (XLByteLE(lsn, PageGetLSN(page)))
 				{
-					LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-					ReleaseBuffer(buffer);
+					UnlockReleaseBuffer(buffer);
 				}
 				else
 				{
@@ -302,8 +300,8 @@ btree_xlog_split(bool onleft, bool isroot,
 
 					PageSetLSN(page, lsn);
 					PageSetTLI(page, ThisTimeLineID);
-					LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-					WriteBuffer(buffer);
+					MarkBufferDirty(buffer);
+					UnlockReleaseBuffer(buffer);
 				}
 			}
 		}
@@ -343,8 +341,7 @@ btree_xlog_delete(XLogRecPtr lsn, XLogRecord *record)
 
 	if (XLByteLE(lsn, PageGetLSN(page)))
 	{
-		LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-		ReleaseBuffer(buffer);
+		UnlockReleaseBuffer(buffer);
 		return;
 	}
 
@@ -361,8 +358,8 @@ btree_xlog_delete(XLogRecPtr lsn, XLogRecord *record)
 
 	PageSetLSN(page, lsn);
 	PageSetTLI(page, ThisTimeLineID);
-	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-	WriteBuffer(buffer);
+	MarkBufferDirty(buffer);
+	UnlockReleaseBuffer(buffer);
 }
 
 static void
@@ -395,8 +392,7 @@ btree_xlog_delete_page(bool ismeta,
 			pageop = (BTPageOpaque) PageGetSpecialPointer(page);
 			if (XLByteLE(lsn, PageGetLSN(page)))
 			{
-				LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-				ReleaseBuffer(buffer);
+				UnlockReleaseBuffer(buffer);
 			}
 			else
 			{
@@ -424,8 +420,8 @@ btree_xlog_delete_page(bool ismeta,
 
 				PageSetLSN(page, lsn);
 				PageSetTLI(page, ThisTimeLineID);
-				LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-				WriteBuffer(buffer);
+				MarkBufferDirty(buffer);
+				UnlockReleaseBuffer(buffer);
 			}
 		}
 	}
@@ -439,8 +435,7 @@ btree_xlog_delete_page(bool ismeta,
 			page = (Page) BufferGetPage(buffer);
 			if (XLByteLE(lsn, PageGetLSN(page)))
 			{
-				LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-				ReleaseBuffer(buffer);
+				UnlockReleaseBuffer(buffer);
 			}
 			else
 			{
@@ -449,8 +444,8 @@ btree_xlog_delete_page(bool ismeta,
 
 				PageSetLSN(page, lsn);
 				PageSetTLI(page, ThisTimeLineID);
-				LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-				WriteBuffer(buffer);
+				MarkBufferDirty(buffer);
+				UnlockReleaseBuffer(buffer);
 			}
 		}
 	}
@@ -466,8 +461,7 @@ btree_xlog_delete_page(bool ismeta,
 				page = (Page) BufferGetPage(buffer);
 				if (XLByteLE(lsn, PageGetLSN(page)))
 				{
-					LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-					ReleaseBuffer(buffer);
+					UnlockReleaseBuffer(buffer);
 				}
 				else
 				{
@@ -476,8 +470,8 @@ btree_xlog_delete_page(bool ismeta,
 
 					PageSetLSN(page, lsn);
 					PageSetTLI(page, ThisTimeLineID);
-					LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-					WriteBuffer(buffer);
+					MarkBufferDirty(buffer);
+					UnlockReleaseBuffer(buffer);
 				}
 			}
 		}
@@ -498,8 +492,8 @@ btree_xlog_delete_page(bool ismeta,
 
 	PageSetLSN(page, lsn);
 	PageSetTLI(page, ThisTimeLineID);
-	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-	WriteBuffer(buffer);
+	MarkBufferDirty(buffer);
+	UnlockReleaseBuffer(buffer);
 
 	/* Update metapage if needed */
 	if (ismeta)
@@ -544,8 +538,8 @@ btree_xlog_newroot(XLogRecPtr lsn, XLogRecord *record)
 
 	PageSetLSN(page, lsn);
 	PageSetTLI(page, ThisTimeLineID);
-	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-	WriteBuffer(buffer);
+	MarkBufferDirty(buffer);
+	UnlockReleaseBuffer(buffer);
 
 	_bt_restore_meta(reln, lsn,
 					 xlrec->rootblk, xlrec->level,