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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.
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24 files changed

+434
-537
lines changed

24 files changed

+434
-537
lines changed

‎src/backend/access/gist/gist.c‎

Lines changed: 37 additions & 41 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/gist/gist.c,v 1.130 2006/03/30 23:03:09 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/gist/gist.c,v 1.131 2006/03/31 23:32:05 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -111,6 +111,9 @@ gistbuild(PG_FUNCTION_ARGS)
111111
START_CRIT_SECTION();
112112

113113
GISTInitBuffer(buffer, F_LEAF);
114+
115+
MarkBufferDirty(buffer);
116+
114117
if (!index->rd_istemp)
115118
{
116119
XLogRecPtr recptr;
@@ -127,8 +130,8 @@ gistbuild(PG_FUNCTION_ARGS)
127130
}
128131
else
129132
PageSetLSN(page, XLogRecPtrForTemp);
130-
LockBuffer(buffer, GIST_UNLOCK);
131-
WriteBuffer(buffer);
133+
134+
UnlockReleaseBuffer(buffer);
132135

133136
END_CRIT_SECTION();
134137

@@ -345,6 +348,15 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
345348
itvec = gistjoinvector(itvec, &tlen, state->itup, state->ituplen);
346349
newitup = gistSplit(state->r, state->stack->buffer, itvec, &tlen, &dist, giststate);
347350

351+
/*
352+
* must mark buffers dirty before XLogInsert, even though we'll
353+
* still be changing their opaque fields below
354+
*/
355+
for (ptr = dist; ptr; ptr = ptr->next)
356+
{
357+
MarkBufferDirty(ptr->buffer);
358+
}
359+
348360
if (!state->r->rd_istemp)
349361
{
350362
XLogRecPtr recptr;
@@ -354,21 +366,17 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
354366
is_leaf, &(state->key), dist);
355367

356368
recptr = XLogInsert(RM_GIST_ID, XLOG_GIST_PAGE_SPLIT, rdata);
357-
ptr = dist;
358-
while (ptr)
369+
for (ptr = dist; ptr; ptr = ptr->next)
359370
{
360371
PageSetLSN(BufferGetPage(ptr->buffer), recptr);
361372
PageSetTLI(BufferGetPage(ptr->buffer), ThisTimeLineID);
362-
ptr = ptr->next;
363373
}
364374
}
365375
else
366376
{
367-
ptr = dist;
368-
while (ptr)
377+
for (ptr = dist; ptr; ptr = ptr->next)
369378
{
370379
PageSetLSN(BufferGetPage(ptr->buffer), XLogRecPtrForTemp);
371-
ptr = ptr->next;
372380
}
373381
}
374382

@@ -379,17 +387,14 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
379387
{
380388
gistnewroot(state->r, state->stack->buffer, state->itup, state->ituplen, &(state->key));
381389
state->needInsertComplete = false;
382-
ptr = dist;
383-
while (ptr)
390+
for (ptr = dist; ptr; ptr = ptr->next)
384391
{
385392
Page page = (Page) BufferGetPage(ptr->buffer);
386393

387394
GistPageGetOpaque(page)->rightlink = (ptr->next) ?
388395
ptr->next->block.blkno : InvalidBlockNumber;
389396
GistPageGetOpaque(page)->nsn = PageGetLSN(page);
390-
LockBuffer(ptr->buffer, GIST_UNLOCK);
391-
WriteBuffer(ptr->buffer);
392-
ptr = ptr->next;
397+
UnlockReleaseBuffer(ptr->buffer);
393398
}
394399
}
395400
else
@@ -430,11 +435,9 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
430435
opaque->rightlink = ourpage->next->block.blkno;
431436

432437
/*
433-
* fills and write all new pages. They isn't linked into tree yet
438+
* fill and release all new pages. They isn't linked into tree yet
434439
*/
435-
436-
ptr = ourpage->next;
437-
while (ptr)
440+
for (ptr = ourpage->next; ptr; ptr = ptr->next)
438441
{
439442
page = (Page) BufferGetPage(ptr->buffer);
440443
GistPageGetOpaque(page)->rightlink = (ptr->next) ?
@@ -443,12 +446,8 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
443446
GistPageGetOpaque(page)->nsn = (ptr->next) ?
444447
opaque->nsn : oldnsn;
445448

446-
LockBuffer(ptr->buffer, GIST_UNLOCK);
447-
WriteBuffer(ptr->buffer);
448-
ptr = ptr->next;
449+
UnlockReleaseBuffer(ptr->buffer);
449450
}
450-
451-
WriteNoReleaseBuffer(state->stack->buffer);
452451
}
453452

454453
END_CRIT_SECTION();
@@ -460,6 +459,8 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
460459

461460
gistfillbuffer(state->r, state->stack->page, state->itup, state->ituplen, InvalidOffsetNumber);
462461

462+
MarkBufferDirty(state->stack->buffer);
463+
463464
oldlsn = PageGetLSN(state->stack->page);
464465
if (!state->r->rd_istemp)
465466
{
@@ -489,7 +490,6 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
489490

490491
if (state->stack->blkno == GIST_ROOT_BLKNO)
491492
state->needInsertComplete = false;
492-
WriteNoReleaseBuffer(state->stack->buffer);
493493

494494
END_CRIT_SECTION();
495495

@@ -561,8 +561,7 @@ gistfindleaf(GISTInsertState *state, GISTSTATE *giststate)
561561
* caused split non-root page is detected, go up to parent to
562562
* choose best child
563563
*/
564-
LockBuffer(state->stack->buffer, GIST_UNLOCK);
565-
ReleaseBuffer(state->stack->buffer);
564+
UnlockReleaseBuffer(state->stack->buffer);
566565
state->stack = state->stack->parent;
567566
continue;
568567
}
@@ -630,8 +629,7 @@ gistfindleaf(GISTInsertState *state, GISTSTATE *giststate)
630629
*/
631630

632631
/* forget buffer */
633-
LockBuffer(state->stack->buffer, GIST_UNLOCK);
634-
ReleaseBuffer(state->stack->buffer);
632+
UnlockReleaseBuffer(state->stack->buffer);
635633

636634
state->stack = state->stack->parent;
637635
continue;
@@ -681,8 +679,7 @@ gistFindPath(Relation r, BlockNumber child)
681679
if (GistPageIsLeaf(page))
682680
{
683681
/* we can safety go away, follows only leaf pages */
684-
LockBuffer(buffer, GIST_UNLOCK);
685-
ReleaseBuffer(buffer);
682+
UnlockReleaseBuffer(buffer);
686683
return NULL;
687684
}
688685

@@ -735,8 +732,7 @@ gistFindPath(Relation r, BlockNumber child)
735732
ptr = ptr->parent;
736733
}
737734
top->childoffnum = i;
738-
LockBuffer(buffer, GIST_UNLOCK);
739-
ReleaseBuffer(buffer);
735+
UnlockReleaseBuffer(buffer);
740736
return top;
741737
}
742738
else
@@ -753,8 +749,7 @@ gistFindPath(Relation r, BlockNumber child)
753749
}
754750
}
755751

756-
LockBuffer(buffer, GIST_UNLOCK);
757-
ReleaseBuffer(buffer);
752+
UnlockReleaseBuffer(buffer);
758753
top = top->next;
759754
}
760755

@@ -801,8 +796,7 @@ gistFindCorrectParent(Relation r, GISTInsertStack *child)
801796
}
802797

803798
parent->blkno = GistPageGetOpaque(parent->page)->rightlink;
804-
LockBuffer(parent->buffer, GIST_UNLOCK);
805-
ReleaseBuffer(parent->buffer);
799+
UnlockReleaseBuffer(parent->buffer);
806800
if (parent->blkno == InvalidBlockNumber)
807801

808802
/*
@@ -881,8 +875,7 @@ gistmakedeal(GISTInsertState *state, GISTSTATE *giststate)
881875
is_splitted = gistplacetopage(state, giststate);
882876

883877
/* parent locked above, so release child buffer */
884-
LockBuffer(state->stack->buffer, GIST_UNLOCK);
885-
ReleaseBuffer(state->stack->buffer);
878+
UnlockReleaseBuffer(state->stack->buffer);
886879

887880
/* pop parent page from stack */
888881
state->stack = state->stack->parent;
@@ -1182,6 +1175,9 @@ gistSplit(Relation r,
11821175
return newtup;
11831176
}
11841177

1178+
/*
1179+
* buffer must be pinned and locked by caller
1180+
*/
11851181
void
11861182
gistnewroot(Relation r, Buffer buffer, IndexTuple *itup, int len, ItemPointer key)
11871183
{
@@ -1192,9 +1188,11 @@ gistnewroot(Relation r, Buffer buffer, IndexTuple *itup, int len, ItemPointer ke
11921188

11931189
START_CRIT_SECTION();
11941190

1195-
GISTInitBuffer(buffer, 0); /* XXX not F_LEAF? */
1191+
GISTInitBuffer(buffer, 0);
11961192
gistfillbuffer(r, page, itup, len, FirstOffsetNumber);
11971193

1194+
MarkBufferDirty(buffer);
1195+
11981196
if (!r->rd_istemp)
11991197
{
12001198
XLogRecPtr recptr;
@@ -1211,8 +1209,6 @@ gistnewroot(Relation r, Buffer buffer, IndexTuple *itup, int len, ItemPointer ke
12111209
else
12121210
PageSetLSN(page, XLogRecPtrForTemp);
12131211

1214-
WriteNoReleaseBuffer(buffer);
1215-
12161212
END_CRIT_SECTION();
12171213
}
12181214

‎src/backend/access/gist/gistvacuum.c‎

Lines changed: 21 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/gist/gistvacuum.c,v 1.17 2006/03/30 23:03:10 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/gist/gistvacuum.c,v 1.18 2006/03/31 23:32:05 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -71,11 +71,7 @@ gistVacuumUpdate(GistVacuum *gv, BlockNumber blkno, bool needunion)
7171
vacuum_delay_point();
7272

7373
buffer = ReadBuffer(gv->index, blkno);
74-
75-
/*
76-
* This is only used during VACUUM FULL, so we need not bother to lock
77-
* individual index pages
78-
*/
74+
LockBuffer(buffer, GIST_EXCLUSIVE);
7975
gistcheckpage(gv->index, buffer);
8076
page = (Page) BufferGetPage(buffer);
8177
maxoff = PageGetMaxOffsetNumber(page);
@@ -183,6 +179,11 @@ gistVacuumUpdate(GistVacuum *gv, BlockNumber blkno, bool needunion)
183179
}
184180
res.itup = vec;
185181

182+
for (ptr = dist; ptr; ptr = ptr->next)
183+
{
184+
MarkBufferDirty(ptr->buffer);
185+
}
186+
186187
if (!gv->index->rd_istemp)
187188
{
188189
XLogRecPtr recptr;
@@ -198,34 +199,29 @@ gistVacuumUpdate(GistVacuum *gv, BlockNumber blkno, bool needunion)
198199
xlinfo = rdata->data;
199200

200201
recptr = XLogInsert(RM_GIST_ID, XLOG_GIST_PAGE_SPLIT, rdata);
201-
ptr = dist;
202-
while (ptr)
202+
for (ptr = dist; ptr; ptr = ptr->next)
203203
{
204204
PageSetLSN(BufferGetPage(ptr->buffer), recptr);
205205
PageSetTLI(BufferGetPage(ptr->buffer), ThisTimeLineID);
206-
ptr = ptr->next;
207206
}
208207

209208
pfree(xlinfo);
210209
pfree(rdata);
211210
}
212211
else
213212
{
214-
ptr = dist;
215-
while (ptr)
213+
for (ptr = dist; ptr; ptr = ptr->next)
216214
{
217215
PageSetLSN(BufferGetPage(ptr->buffer), XLogRecPtrForTemp);
218-
ptr = ptr->next;
219216
}
220217
}
221218

222-
ptr = dist;
223-
while (ptr)
219+
for (ptr = dist; ptr; ptr = ptr->next)
224220
{
221+
/* we must keep the buffer lock on the head page */
225222
if (BufferGetBlockNumber(ptr->buffer) != blkno)
226223
LockBuffer(ptr->buffer, GIST_UNLOCK);
227-
WriteBuffer(ptr->buffer);
228-
ptr = ptr->next;
224+
ReleaseBuffer(ptr->buffer);
229225
}
230226

231227
if (blkno == GIST_ROOT_BLKNO)
@@ -297,6 +293,8 @@ gistVacuumUpdate(GistVacuum *gv, BlockNumber blkno, bool needunion)
297293

298294
if (needwrite)
299295
{
296+
MarkBufferDirty(buffer);
297+
300298
if (!gv->index->rd_istemp)
301299
{
302300
XLogRecData *rdata;
@@ -317,13 +315,12 @@ gistVacuumUpdate(GistVacuum *gv, BlockNumber blkno, bool needunion)
317315
}
318316
else
319317
PageSetLSN(page, XLogRecPtrForTemp);
320-
WriteBuffer(buffer);
321318
}
322-
else
323-
ReleaseBuffer(buffer);
324319

325320
END_CRIT_SECTION();
326321

322+
UnlockReleaseBuffer(buffer);
323+
327324
if (ncompleted && !gv->index->rd_istemp)
328325
gistxlogInsertCompletion(gv->index->rd_node, completed, ncompleted);
329326

@@ -429,8 +426,7 @@ gistvacuumcleanup(PG_FUNCTION_ARGS)
429426
}
430427
else
431428
lastFilledBlock = blkno;
432-
LockBuffer(buffer, GIST_UNLOCK);
433-
ReleaseBuffer(buffer);
429+
UnlockReleaseBuffer(buffer);
434430
}
435431
lastBlock = npages - 1;
436432

@@ -569,8 +565,7 @@ gistbulkdelete(PG_FUNCTION_ARGS)
569565
if (stack->blkno == GIST_ROOT_BLKNO && !GistPageIsLeaf(page))
570566
{
571567
/* only the root can become non-leaf during relock */
572-
LockBuffer(buffer, GIST_UNLOCK);
573-
ReleaseBuffer(buffer);
568+
UnlockReleaseBuffer(buffer);
574569
/* one more check */
575570
continue;
576571
}
@@ -617,6 +612,8 @@ gistbulkdelete(PG_FUNCTION_ARGS)
617612
{
618613
GistMarkTuplesDeleted(page);
619614

615+
MarkBufferDirty(buffer);
616+
620617
if (!rel->rd_istemp)
621618
{
622619
XLogRecData *rdata;
@@ -638,7 +635,6 @@ gistbulkdelete(PG_FUNCTION_ARGS)
638635
}
639636
else
640637
PageSetLSN(page, XLogRecPtrForTemp);
641-
WriteNoReleaseBuffer(buffer);
642638
}
643639

644640
END_CRIT_SECTION();
@@ -666,8 +662,7 @@ gistbulkdelete(PG_FUNCTION_ARGS)
666662
}
667663
}
668664

669-
LockBuffer(buffer, GIST_UNLOCK);
670-
ReleaseBuffer(buffer);
665+
UnlockReleaseBuffer(buffer);
671666

672667
ptr = stack->next;
673668
pfree(stack);

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