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Allocate page cache headers and page cache data buffers separately.

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The data buffer will be a power of two in size and this gives some
malloc implementation additional optimization opportunitites. (CVS 4409)

FossilOrigin-Name: 2b755defe51a565a2b6ace58381d6e91f6f17db8
This commit is contained in:
drh
2007-09-06 22:19:14 +00:00
parent 24e824c4eb
commit bf4bca541e
5 changed files with 61 additions and 48 deletions
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25
src/btree.c
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@@ -9,7 +9,7 @@
** May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.422 2007/09/03 22:00:39 drh Exp $
** $Id: btree.c,v 1.423 2007/09/06 22:19:15 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
@@ -902,7 +902,8 @@ int sqlite3BtreeInitPage(
assert( pParent==0 || pParent->pBt==pBt );
assert( sqlite3_mutex_held(pBt->mutex) );
assert( pPage->pgno==sqlite3PagerPagenumber(pPage->pDbPage) );
assert( pPage->aData == &((unsigned char*)pPage)[-pBt->pageSize] );
assert( pPage == sqlite3PagerGetExtra(pPage->pDbPage) );
assert( pPage->aData == sqlite3PagerGetData(pPage->pDbPage) );
if( pPage->pParent!=pParent && (pPage->pParent!=0 || pPage->isInit) ){
/* The parent page should never change unless the file is corrupt */
return SQLITE_CORRUPT_BKPT;
@@ -969,7 +970,8 @@ static void zeroPage(MemPage *pPage, int flags){
int first;
assert( sqlite3PagerPagenumber(pPage->pDbPage)==pPage->pgno );
assert( &data[pBt->pageSize] == (unsigned char*)pPage );
assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
assert( sqlite3PagerGetData(pPage->pDbPage) == data );
assert( sqlite3PagerIswriteable(pPage->pDbPage) );
assert( sqlite3_mutex_held(pBt->mutex) );
memset(&data[hdr], 0, pBt->usableSize - hdr);
@@ -1053,7 +1055,8 @@ static void releasePage(MemPage *pPage){
if( pPage ){
assert( pPage->aData );
assert( pPage->pBt );
assert( &pPage->aData[pPage->pBt->pageSize]==(unsigned char*)pPage );
assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData );
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
sqlite3PagerUnref(pPage->pDbPage);
}
@@ -1731,7 +1734,7 @@ static void unlockBtreeIfUnused(BtShared *pBt){
if( sqlite3PagerRefcount(pBt->pPager)>=1 ){
if( pBt->pPage1->aData==0 ){
MemPage *pPage = pBt->pPage1;
pPage->aData = &((u8*)pPage)[-pBt->pageSize];
pPage->aData = sqlite3PagerGetData(pPage->pDbPage);
pPage->pBt = pBt;
pPage->pgno = 1;
}
@@ -4348,7 +4351,7 @@ static int reparentPage(BtShared *pBt, Pgno pgno, MemPage *pNewParent, int idx){
if( pDbPage ){
pThis = (MemPage *)sqlite3PagerGetExtra(pDbPage);
if( pThis->isInit ){
assert( pThis->aData==(sqlite3PagerGetData(pDbPage)) );
assert( pThis->aData==sqlite3PagerGetData(pDbPage) );
if( pThis->pParent!=pNewParent ){
if( pThis->pParent ) sqlite3PagerUnref(pThis->pParent->pDbPage);
pThis->pParent = pNewParent;
@@ -4899,12 +4902,10 @@ static int balance_nonroot(MemPage *pPage){
** process of being overwritten.
*/
for(i=0; i<nOld; i++){
MemPage *p = apCopy[i] = (MemPage*)&aCopy[i][pBt->pageSize];
p->aData = &((u8*)p)[-pBt->pageSize];
memcpy(p->aData, apOld[i]->aData, pBt->pageSize + sizeof(MemPage));
/* The memcpy() above changes the value of p->aData so we have to
** set it again. */
p->aData = &((u8*)p)[-pBt->pageSize];
MemPage *p = apCopy[i] = (MemPage*)aCopy[i];
memcpy(p, apOld[i], sizeof(MemPage));
p->aData = (void*)&p[1];
memcpy(p->aData, apOld[i]->aData, pBt->pageSize);
}
/*