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Get rid of page-level locking in btree-s.

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LockBuffer is used to acquire read/write access
to index pages. Pages are released before leaving
index internals.
This commit is contained in:
Vadim B. Mikheev
1999-05-25 18:20:31 +00:00
parent 07842084fe
commit 7d443a85af
7 changed files with 73 additions and 132 deletions
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92
src/backend/access/nbtree/nbtpage.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtpage.c,v 1.21 1999/05/25 16:07:26 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtpage.c,v 1.22 1999/05/25 18:20:29 vadim Exp $
*
* NOTES
* Postgres btree pages look like ordinary relation pages. The opaque
@@ -27,7 +27,6 @@
#include <storage/bufpage.h>
#include <access/nbtree.h>
#include <miscadmin.h>
#include <storage/bufmgr.h>
#include <storage/lmgr.h>
#ifndef HAVE_MEMMOVE
@@ -36,26 +35,17 @@
#include <string.h>
#endif
static void _bt_setpagelock(Relation rel, BlockNumber blkno, int access);
static void _bt_unsetpagelock(Relation rel, BlockNumber blkno, int access);
#define BTREE_METAPAGE 0
#define BTREE_MAGIC 0x053162
#ifdef BTREE_VERSION_1
#define BTREE_VERSION 1
#else
#define BTREE_VERSION 0
#endif
typedef struct BTMetaPageData
{
uint32 btm_magic;
uint32 btm_version;
BlockNumber btm_root;
#ifdef BTREE_VERSION_1
int32 btm_level;
#endif
} BTMetaPageData;
#define BTPageGetMeta(p) \
@@ -108,9 +98,7 @@ _bt_metapinit(Relation rel)
metad.btm_magic = BTREE_MAGIC;
metad.btm_version = BTREE_VERSION;
metad.btm_root = P_NONE;
#ifdef BTREE_VERSION_1
metad.btm_level = 0;
#endif
memmove((char *) BTPageGetMeta(pg), (char *) &metad, sizeof(metad));
op = (BTPageOpaque) PageGetSpecialPointer(pg);
@@ -246,9 +234,7 @@ _bt_getroot(Relation rel, int access)
rootblkno = BufferGetBlockNumber(rootbuf);
rootpg = BufferGetPage(rootbuf);
metad->btm_root = rootblkno;
#ifdef BTREE_VERSION_1
metad->btm_level = 1;
#endif
_bt_pageinit(rootpg, BufferGetPageSize(rootbuf));
rootopaque = (BTPageOpaque) PageGetSpecialPointer(rootpg);
rootopaque->btpo_flags |= (BTP_LEAF | BTP_ROOT);
@@ -257,8 +243,8 @@ _bt_getroot(Relation rel, int access)
/* swap write lock for read lock, if appropriate */
if (access != BT_WRITE)
{
_bt_setpagelock(rel, rootblkno, BT_READ);
_bt_unsetpagelock(rel, rootblkno, BT_WRITE);
LockBuffer(rootbuf, BUFFER_LOCK_UNLOCK);
LockBuffer(rootbuf, BT_READ);
}
/* okay, metadata is correct */
@@ -322,31 +308,24 @@ _bt_getbuf(Relation rel, BlockNumber blkno, int access)
Buffer buf;
Page page;
/*
* If we want a new block, we can't set a lock of the appropriate type
* until we've instantiated the buffer.
*/
if (blkno != P_NEW)
{
if (access == BT_WRITE)
_bt_setpagelock(rel, blkno, BT_WRITE);
else
_bt_setpagelock(rel, blkno, BT_READ);
buf = ReadBuffer(rel, blkno);
LockBuffer(buf, access);
}
else
{
/*
* Extend bufmgr code is unclean and so we have to
* use locking here.
*/
LockPage(rel, 0, ExclusiveLock);
buf = ReadBuffer(rel, blkno);
UnlockPage(rel, 0, ExclusiveLock);
blkno = BufferGetBlockNumber(buf);
page = BufferGetPage(buf);
_bt_pageinit(page, BufferGetPageSize(buf));
if (access == BT_WRITE)
_bt_setpagelock(rel, blkno, BT_WRITE);
else
_bt_setpagelock(rel, blkno, BT_READ);
LockBuffer(buf, access);
}
/* ref count and lock type are correct */
@@ -359,16 +338,7 @@ _bt_getbuf(Relation rel, BlockNumber blkno, int access)
void
_bt_relbuf(Relation rel, Buffer buf, int access)
{
BlockNumber blkno;
blkno = BufferGetBlockNumber(buf);
/* access had better be one of read or write */
if (access == BT_WRITE)
_bt_unsetpagelock(rel, blkno, BT_WRITE);
else
_bt_unsetpagelock(rel, blkno, BT_READ);
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buf);
}
@@ -382,11 +352,8 @@ _bt_relbuf(Relation rel, Buffer buf, int access)
void
_bt_wrtbuf(Relation rel, Buffer buf)
{
BlockNumber blkno;
blkno = BufferGetBlockNumber(buf);
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
WriteBuffer(buf);
_bt_unsetpagelock(rel, blkno, BT_WRITE);
}
/*
@@ -399,9 +366,6 @@ _bt_wrtbuf(Relation rel, Buffer buf)
void
_bt_wrtnorelbuf(Relation rel, Buffer buf)
{
BlockNumber blkno;
blkno = BufferGetBlockNumber(buf);
WriteNoReleaseBuffer(buf);
}
@@ -452,12 +416,10 @@ _bt_metaproot(Relation rel, BlockNumber rootbknum, int level)
Assert(metaopaque->btpo_flags & BTP_META);
metad = BTPageGetMeta(metap);
metad->btm_root = rootbknum;
#ifdef BTREE_VERSION_1
if (level == 0) /* called from _do_insert */
if (level == 0) /* called from _do_insert */
metad->btm_level += 1;
else
metad->btm_level = level; /* called from btsort */
#endif
_bt_wrtbuf(rel, metabuf);
}
@@ -582,32 +544,6 @@ _bt_getstackbuf(Relation rel, BTStack stack, int access)
}
}
static void
_bt_setpagelock(Relation rel, BlockNumber blkno, int access)
{
if (USELOCKING)
{
if (access == BT_WRITE)
LockPage(rel, blkno, ExclusiveLock);
else
LockPage(rel, blkno, ShareLock);
}
}
static void
_bt_unsetpagelock(Relation rel, BlockNumber blkno, int access)
{
if (USELOCKING)
{
if (access == BT_WRITE)
UnlockPage(rel, blkno, ExclusiveLock);
else
UnlockPage(rel, blkno, ShareLock);
}
}
void
_bt_pagedel(Relation rel, ItemPointer tid)
{