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, 5 insertions, 14 deletions

diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c
index 5a86a7c7628..31d5c27e793 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/buffer/localbuf.c,v 1.73 2006/03/05 15:58:36 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/buffer/localbuf.c,v 1.74 2006/03/31 23:32:06 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -209,11 +209,11 @@ LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr)
 }
 
 /*
- * WriteLocalBuffer -
- *	  writes out a local buffer (actually, just marks it dirty)
+ * MarkLocalBufferDirty -
+ *	  mark a local buffer dirty
  */
 void
-WriteLocalBuffer(Buffer buffer, bool release)
+MarkLocalBufferDirty(Buffer buffer)
 {
 	int			bufid;
 	BufferDesc *bufHdr;
@@ -221,7 +221,7 @@ WriteLocalBuffer(Buffer buffer, bool release)
 	Assert(BufferIsLocal(buffer));
 
 #ifdef LBDEBUG
-	fprintf(stderr, "LB WRITE %d\n", buffer);
+	fprintf(stderr, "LB DIRTY %d\n", buffer);
 #endif
 
 	bufid = -(buffer + 1);
@@ -230,15 +230,6 @@ WriteLocalBuffer(Buffer buffer, bool release)
 
 	bufHdr = &LocalBufferDescriptors[bufid];
 	bufHdr->flags |= BM_DIRTY;
-
-	if (release)
-	{
-		LocalRefCount[bufid]--;
-		if (LocalRefCount[bufid] == 0 &&
-			bufHdr->usage_count < BM_MAX_USAGE_COUNT)
-			bufHdr->usage_count++;
-		ResourceOwnerForgetBuffer(CurrentResourceOwner, buffer);
-	}
 }
 
 /*