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Commit 7d443a8

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vadim4ovadim4o
committed
Get rid of page-level locking in btree-s.
LockBuffer is used to acquire read/write access to index pages. Pages are released before leaving index internals.
1 parent 0784208 commit 7d443a8

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7 files changed

+73
-132
lines changed

7 files changed

+73
-132
lines changed

‎src/backend/access/nbtree/nbtinsert.c

+18-20
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.40 1999/05/25 16:07:23 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.41 1999/05/25 18:20:28 vadim Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -19,7 +19,6 @@
1919
#include <access/nbtree.h>
2020
#include <access/heapam.h>
2121
#include <access/xact.h>
22-
#include <storage/bufmgr.h>
2322
#include <fmgr.h>
2423

2524
#ifndef HAVE_MEMMOVE
@@ -64,14 +63,11 @@ _bt_doinsert(Relation rel, BTItem btitem, bool index_is_unique, Relation heapRel
6463
/* find the page containing this key */
6564
stack = _bt_search(rel, natts, itup_scankey, &buf);
6665

67-
blkno = BufferGetBlockNumber(buf);
68-
6966
/* trade in our read lock for a write lock */
70-
_bt_relbuf(rel, buf, BT_READ);
67+
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
68+
LockBuffer(buf, BT_WRITE);
7169

7270
l1:
73-
buf = _bt_getbuf(rel, blkno, BT_WRITE);
74-
7571
/*
7672
* If the page was split between the time that we surrendered our read
7773
* lock and acquired our write lock, then this page may no longer be
@@ -81,6 +77,7 @@ _bt_doinsert(Relation rel, BTItem btitem, bool index_is_unique, Relation heapRel
8177
*/
8278

8379
buf = _bt_moveright(rel, buf, natts, itup_scankey, BT_WRITE);
80+
blkno = BufferGetBlockNumber(buf);
8481

8582
/* if we're not allowing duplicates, make sure the key isn't */
8683
/* already in the node */
@@ -99,13 +96,13 @@ _bt_doinsert(Relation rel, BTItem btitem, bool index_is_unique, Relation heapRel
9996
/* key on the page before trying to compare it */
10097
if (!PageIsEmpty(page) && offset <= maxoff)
10198
{
102-
TupleDesc itupdesc;
103-
BTItem cbti;
104-
HeapTupleData htup;
105-
BTPageOpaque opaque;
106-
Buffer nbuf;
107-
BlockNumber blkno;
108-
bool chtup = true;
99+
TupleDesc itupdesc;
100+
BTItem cbti;
101+
HeapTupleData htup;
102+
BTPageOpaque opaque;
103+
Buffer nbuf;
104+
BlockNumber nblkno;
105+
bool chtup = true;
109106

110107
itupdesc = RelationGetDescr(rel);
111108
nbuf = InvalidBuffer;
@@ -157,7 +154,8 @@ _bt_doinsert(Relation rel, BTItem btitem, bool index_is_unique, Relation heapRel
157154
_bt_relbuf(rel, nbuf, BT_READ);
158155
_bt_relbuf(rel, buf, BT_WRITE);
159156
XactLockTableWait(xwait);
160-
goto l1;/* continue from the begin */
157+
buf = _bt_getbuf(rel, blkno, BT_WRITE);
158+
goto l1; /* continue from the begin */
161159
}
162160
elog(ERROR, "Cannot insert a duplicate key into a unique index");
163161
}
@@ -177,12 +175,12 @@ _bt_doinsert(Relation rel, BTItem btitem, bool index_is_unique, Relation heapRel
177175
* min key of the right page is the same, ooh - so
178176
* many dead duplicates...
179177
*/
180-
blkno = opaque->btpo_next;
178+
nblkno = opaque->btpo_next;
181179
if (nbuf != InvalidBuffer)
182180
_bt_relbuf(rel, nbuf, BT_READ);
183-
for (nbuf = InvalidBuffer;;)
181+
for (nbuf = InvalidBuffer; ; )
184182
{
185-
nbuf = _bt_getbuf(rel, blkno, BT_READ);
183+
nbuf = _bt_getbuf(rel, nblkno, BT_READ);
186184
page = BufferGetPage(nbuf);
187185
maxoff = PageGetMaxOffsetNumber(page);
188186
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
@@ -193,10 +191,10 @@ _bt_doinsert(Relation rel, BTItem btitem, bool index_is_unique, Relation heapRel
193191
}
194192
else
195193
{ /* Empty or "pseudo"-empty page - get next */
196-
blkno = opaque->btpo_next;
194+
nblkno = opaque->btpo_next;
197195
_bt_relbuf(rel, nbuf, BT_READ);
198196
nbuf = InvalidBuffer;
199-
if (blkno == P_NONE)
197+
if (nblkno == P_NONE)
200198
break;
201199
}
202200
}

‎src/backend/access/nbtree/nbtpage.c

+14-78
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtpage.c,v 1.21 1999/05/25 16:07:26 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtpage.c,v 1.22 1999/05/25 18:20:29 vadim Exp $
1212
*
1313
* NOTES
1414
* Postgres btree pages look like ordinary relation pages. The opaque
@@ -27,7 +27,6 @@
2727
#include <storage/bufpage.h>
2828
#include <access/nbtree.h>
2929
#include <miscadmin.h>
30-
#include <storage/bufmgr.h>
3130
#include <storage/lmgr.h>
3231

3332
#ifndef HAVE_MEMMOVE
@@ -36,26 +35,17 @@
3635
#include <string.h>
3736
#endif
3837

39-
static void _bt_setpagelock(Relation rel, BlockNumber blkno, int access);
40-
static void _bt_unsetpagelock(Relation rel, BlockNumber blkno, int access);
41-
4238
#define BTREE_METAPAGE 0
4339
#define BTREE_MAGIC 0x053162
4440

45-
#ifdef BTREE_VERSION_1
4641
#define BTREE_VERSION 1
47-
#else
48-
#define BTREE_VERSION 0
49-
#endif
5042

5143
typedef struct BTMetaPageData
5244
{
5345
uint32 btm_magic;
5446
uint32 btm_version;
5547
BlockNumber btm_root;
56-
#ifdef BTREE_VERSION_1
5748
int32 btm_level;
58-
#endif
5949
} BTMetaPageData;
6050

6151
#define BTPageGetMeta(p) \
@@ -108,9 +98,7 @@ _bt_metapinit(Relation rel)
10898
metad.btm_magic = BTREE_MAGIC;
10999
metad.btm_version = BTREE_VERSION;
110100
metad.btm_root = P_NONE;
111-
#ifdef BTREE_VERSION_1
112101
metad.btm_level = 0;
113-
#endif
114102
memmove((char *) BTPageGetMeta(pg), (char *) &metad, sizeof(metad));
115103

116104
op = (BTPageOpaque) PageGetSpecialPointer(pg);
@@ -246,9 +234,7 @@ _bt_getroot(Relation rel, int access)
246234
rootblkno = BufferGetBlockNumber(rootbuf);
247235
rootpg = BufferGetPage(rootbuf);
248236
metad->btm_root = rootblkno;
249-
#ifdef BTREE_VERSION_1
250237
metad->btm_level = 1;
251-
#endif
252238
_bt_pageinit(rootpg, BufferGetPageSize(rootbuf));
253239
rootopaque = (BTPageOpaque) PageGetSpecialPointer(rootpg);
254240
rootopaque->btpo_flags |= (BTP_LEAF | BTP_ROOT);
@@ -257,8 +243,8 @@ _bt_getroot(Relation rel, int access)
257243
/* swap write lock for read lock, if appropriate */
258244
if (access != BT_WRITE)
259245
{
260-
_bt_setpagelock(rel, rootblkno, BT_READ);
261-
_bt_unsetpagelock(rel, rootblkno, BT_WRITE);
246+
LockBuffer(rootbuf, BUFFER_LOCK_UNLOCK);
247+
LockBuffer(rootbuf, BT_READ);
262248
}
263249

264250
/* okay, metadata is correct */
@@ -322,31 +308,24 @@ _bt_getbuf(Relation rel, BlockNumber blkno, int access)
322308
Buffer buf;
323309
Page page;
324310

325-
/*
326-
* If we want a new block, we can't set a lock of the appropriate type
327-
* until we've instantiated the buffer.
328-
*/
329-
330311
if (blkno != P_NEW)
331312
{
332-
if (access == BT_WRITE)
333-
_bt_setpagelock(rel, blkno, BT_WRITE);
334-
else
335-
_bt_setpagelock(rel, blkno, BT_READ);
336-
337313
buf = ReadBuffer(rel, blkno);
314+
LockBuffer(buf, access);
338315
}
339316
else
340317
{
318+
/*
319+
* Extend bufmgr code is unclean and so we have to
320+
* use locking here.
321+
*/
322+
LockPage(rel, 0, ExclusiveLock);
341323
buf = ReadBuffer(rel, blkno);
324+
UnlockPage(rel, 0, ExclusiveLock);
342325
blkno = BufferGetBlockNumber(buf);
343326
page = BufferGetPage(buf);
344327
_bt_pageinit(page, BufferGetPageSize(buf));
345-
346-
if (access == BT_WRITE)
347-
_bt_setpagelock(rel, blkno, BT_WRITE);
348-
else
349-
_bt_setpagelock(rel, blkno, BT_READ);
328+
LockBuffer(buf, access);
350329
}
351330

352331
/* ref count and lock type are correct */
@@ -359,16 +338,7 @@ _bt_getbuf(Relation rel, BlockNumber blkno, int access)
359338
void
360339
_bt_relbuf(Relation rel, Buffer buf, int access)
361340
{
362-
BlockNumber blkno;
363-
364-
blkno = BufferGetBlockNumber(buf);
365-
366-
/* access had better be one of read or write */
367-
if (access == BT_WRITE)
368-
_bt_unsetpagelock(rel, blkno, BT_WRITE);
369-
else
370-
_bt_unsetpagelock(rel, blkno, BT_READ);
371-
341+
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
372342
ReleaseBuffer(buf);
373343
}
374344

@@ -382,11 +352,8 @@ _bt_relbuf(Relation rel, Buffer buf, int access)
382352
void
383353
_bt_wrtbuf(Relation rel, Buffer buf)
384354
{
385-
BlockNumber blkno;
386-
387-
blkno = BufferGetBlockNumber(buf);
355+
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
388356
WriteBuffer(buf);
389-
_bt_unsetpagelock(rel, blkno, BT_WRITE);
390357
}
391358

392359
/*
@@ -399,9 +366,6 @@ _bt_wrtbuf(Relation rel, Buffer buf)
399366
void
400367
_bt_wrtnorelbuf(Relation rel, Buffer buf)
401368
{
402-
BlockNumber blkno;
403-
404-
blkno = BufferGetBlockNumber(buf);
405369
WriteNoReleaseBuffer(buf);
406370
}
407371

@@ -452,12 +416,10 @@ _bt_metaproot(Relation rel, BlockNumber rootbknum, int level)
452416
Assert(metaopaque->btpo_flags & BTP_META);
453417
metad = BTPageGetMeta(metap);
454418
metad->btm_root = rootbknum;
455-
#ifdef BTREE_VERSION_1
456-
if (level == 0) /* called from _do_insert */
419+
if (level == 0) /* called from _do_insert */
457420
metad->btm_level += 1;
458421
else
459422
metad->btm_level = level; /* called from btsort */
460-
#endif
461423
_bt_wrtbuf(rel, metabuf);
462424
}
463425

@@ -582,32 +544,6 @@ _bt_getstackbuf(Relation rel, BTStack stack, int access)
582544
}
583545
}
584546

585-
static void
586-
_bt_setpagelock(Relation rel, BlockNumber blkno, int access)
587-
{
588-
589-
if (USELOCKING)
590-
{
591-
if (access == BT_WRITE)
592-
LockPage(rel, blkno, ExclusiveLock);
593-
else
594-
LockPage(rel, blkno, ShareLock);
595-
}
596-
}
597-
598-
static void
599-
_bt_unsetpagelock(Relation rel, BlockNumber blkno, int access)
600-
{
601-
602-
if (USELOCKING)
603-
{
604-
if (access == BT_WRITE)
605-
UnlockPage(rel, blkno, ExclusiveLock);
606-
else
607-
UnlockPage(rel, blkno, ShareLock);
608-
}
609-
}
610-
611547
void
612548
_bt_pagedel(Relation rel, ItemPointer tid)
613549
{

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