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vadim4ovadim4o
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No more LateWrite, but there is WriteMode;
SetBufferWriteMode () added; FlushBuffer () fixed: now directly calls smgrflush () and releases buffer only if required by caller.
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-17
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+44
-17
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‎src/backend/storage/buffer/bufmgr.c

Lines changed: 44 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.7 1997/01/14 05:40:45 vadim Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.8 1997/01/16 08:11:41 vadim Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -26,7 +26,7 @@
2626
*
2727
* WriteNoReleaseBuffer() -- mark the buffer contents as "dirty"
2828
* but don't unpin. The disk IO is delayed until buffer
29-
* replacement if LateWrite flag is set.
29+
* replacement if WriteMode is BUFFER_LATE_WRITE.
3030
*
3131
* WriteBuffer() -- WriteNoReleaseBuffer() + ReleaseBuffer()
3232
*
@@ -74,12 +74,13 @@
7474
#include "executor/execdebug.h" /* for NDirectFileRead */
7575
#include "catalog/catalog.h"
7676

77-
extern int LateWrite;
7877
extern SPINLOCK BufMgrLock;
7978
extern int ReadBufferCount;
8079
extern int BufferHitCount;
8180
extern int BufferFlushCount;
8281

82+
static int WriteMode = BUFFER_LATE_WRITE; /* Delayed write is default */
83+
8384
static void WaitIO(BufferDesc *buf, SPINLOCK spinlock);
8485
#ifndef HAS_TEST_AND_SET
8586
static void SignalIO(BufferDesc *buf);
@@ -90,7 +91,7 @@ static Buffer ReadBufferWithBufferLock(Relation relation, BlockNumber blockNum,
9091
bool bufferLockHeld);
9192
static BufferDesc *BufferAlloc(Relation reln, BlockNumber blockNum,
9293
bool *foundPtr, bool bufferLockHeld);
93-
static int FlushBuffer(Buffer buffer);
94+
static int FlushBuffer (Buffer buffer, bool release);
9495
static void BufferSync(void);
9596
static int BufferReplace(BufferDesc *bufHdr, bool bufferLockHeld);
9697

@@ -611,8 +612,8 @@ BufferAlloc(Relation reln,
611612
/*
612613
* WriteBuffer--
613614
*
614-
* Pushes buffer contents to disk if LateWrite is
615-
* not set. Otherwise, marks contents as dirty.
615+
* Pushes buffer contents to disk if WriteMode is BUFFER_FLUSH_WRITE.
616+
* Otherwise, marks contents as dirty.
616617
*
617618
* Assume that buffer is pinned. Assume that reln is
618619
* valid.
@@ -628,8 +629,8 @@ WriteBuffer(Buffer buffer)
628629
{
629630
BufferDesc *bufHdr;
630631

631-
if (! LateWrite) {
632-
return(FlushBuffer(buffer));
632+
if (WriteMode == BUFFER_FLUSH_WRITE) {
633+
return (FlushBuffer (buffer, TRUE));
633634
} else {
634635

635636
if (BufferIsLocal(buffer))
@@ -712,26 +713,41 @@ DirtyBufferCopy(Oid dbid, Oid relid, BlockNumber blkno, char *dest)
712713
* us).
713714
*/
714715
static int
715-
FlushBuffer(Buffer buffer)
716+
FlushBuffer(Buffer buffer, bool release)
716717
{
717718
BufferDesc *bufHdr;
719+
Oid bufdb;
720+
Relation bufrel;
721+
int status;
718722

719723
if (BufferIsLocal(buffer))
720-
return FlushLocalBuffer(buffer);
724+
return FlushLocalBuffer(buffer, release);
721725

722726
if (BAD_BUFFER_ID(buffer))
723727
return (STATUS_ERROR);
724728

725729
bufHdr = &BufferDescriptors[buffer-1];
730+
bufdb = bufHdr->tag.relId.dbId;
726731

727-
if (!BufferReplace(bufHdr, false)) {
728-
elog(WARN, "FlushBuffer: cannot flush %d", bufHdr->tag.blockNum);
732+
Assert (bufdb == MyDatabaseId || bufdb == (Oid) NULL);
733+
bufrel = RelationIdCacheGetRelation (bufHdr->tag.relId.relId);
734+
Assert (bufrel != (Relation) NULL);
735+
736+
status = smgrflush(bufHdr->bufsmgr, bufrel, bufHdr->tag.blockNum,
737+
(char *) MAKE_PTR(bufHdr->data));
738+
739+
if (status == SM_FAIL)
740+
{
741+
elog(WARN, "FlushBuffer: cannot flush block %u of the relation %.*s",
742+
bufHdr->tag.blockNum,
743+
NAMEDATALEN, bufrel->rd_rel->relname.data);
729744
return (STATUS_ERROR);
730745
}
731746

732747
SpinAcquire(BufMgrLock);
733748
bufHdr->flags &= ~BM_DIRTY;
734-
UnpinBuffer(bufHdr);
749+
if ( release )
750+
UnpinBuffer(bufHdr);
735751
SpinRelease(BufMgrLock);
736752

737753
return(STATUS_OK);
@@ -750,8 +766,8 @@ WriteNoReleaseBuffer(Buffer buffer)
750766
{
751767
BufferDesc *bufHdr;
752768

753-
if (! LateWrite) {
754-
return(FlushBuffer(buffer));
769+
if (WriteMode == BUFFER_FLUSH_WRITE) {
770+
return (FlushBuffer (buffer, FALSE));
755771
} else {
756772

757773
if (BufferIsLocal(buffer))
@@ -899,7 +915,11 @@ BufferSync()
899915
elog(WARN, "cannot write %u for %s",
900916
bufHdr->tag.blockNum, bufHdr->sb_relname);
901917
}
902-
918+
/*
919+
* What if someone has marked this buffer as DIRTY after
920+
* smgr[blind]write but before SpinAcquire(BufMgrLock)
921+
* ??? - vadim 01/16/97
922+
*/
903923
bufHdr->flags &= ~BM_DIRTY;
904924
if (reln != (Relation)NULL)
905925
RelationDecrementReferenceCount(reln);
@@ -1145,7 +1165,6 @@ BufferGetRelation(Buffer buffer)
11451165
*
11461166
* Flush the buffer corresponding to 'bufHdr'
11471167
*
1148-
* Assumes that the BufMgrLock has NOT been acquired.
11491168
*/
11501169
static int
11511170
BufferReplace(BufferDesc *bufHdr, bool bufferLockHeld)
@@ -1655,3 +1674,11 @@ BufferRefCountRestore(int *refcountsave)
16551674
}
16561675
}
16571676

1677+
int SetBufferWriteMode (int mode)
1678+
{
1679+
int old;
1680+
1681+
old = WriteMode;
1682+
WriteMode = mode;
1683+
return (old);
1684+
}

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