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Smaller and faster implementation of the fillInCell() routine.

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FossilOrigin-Name: 77074990edef6c42bdfe7ccce1affc8ed64a86dde3ad4fa50b60ba0a6d851eea
This commit is contained in:
drh
2017-08-23 14:45:59 +00:00
parent 489a224bea
commit 5e27e1dc49
3 changed files with 63 additions and 50 deletions
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99
src/btree.c
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@@ -6218,21 +6218,20 @@ static int fillInCell(
){
int nPayload;
const u8 *pSrc;
int nSrc, n, rc;
int nSrc, n, rc, mn;
int spaceLeft;
MemPage *pOvfl = 0;
MemPage *pToRelease = 0;
MemPage *pToRelease;
unsigned char *pPrior;
unsigned char *pPayload;
BtShared *pBt = pPage->pBt;
Pgno pgnoOvfl = 0;
BtShared *pBt;
Pgno pgnoOvfl;
int nHeader;
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
/* pPage is not necessarily writeable since pCell might be auxiliary
** buffer space that is separate from the pPage buffer area */
assert( pCell<pPage->aData || pCell>=&pPage->aData[pBt->pageSize]
assert( pCell<pPage->aData || pCell>=&pPage->aData[pPage->pBt->pageSize]
|| sqlite3PagerIswriteable(pPage->pDbPage) );
/* Fill in the header. */
@@ -6252,25 +6251,36 @@ static int fillInCell(
}
/* Fill in the payload */
pPayload = &pCell[nHeader];
if( nPayload<=pPage->maxLocal ){
/* This is the common case where everything fits on the btree page
** and no overflow pages are required. */
n = nHeader + nPayload;
testcase( n==3 );
testcase( n==4 );
if( n<4 ) n = 4;
*pnSize = n;
spaceLeft = nPayload;
pPrior = pCell;
}else{
int mn = pPage->minLocal;
n = mn + (nPayload - mn) % (pPage->pBt->usableSize - 4);
testcase( n==pPage->maxLocal );
testcase( n==pPage->maxLocal+1 );
if( n > pPage->maxLocal ) n = mn;
spaceLeft = n;
*pnSize = n + nHeader + 4;
pPrior = &pCell[nHeader+n];
assert( nSrc<=nPayload );
testcase( nSrc<nPayload );
memcpy(pPayload, pSrc, nSrc);
memset(pPayload+nSrc, 0, nPayload-nSrc);
return SQLITE_OK;
}
pPayload = &pCell[nHeader];
/* If we reach this point, it means that some of the content will need
** to spill onto overflow pages.
*/
mn = pPage->minLocal;
n = mn + (nPayload - mn) % (pPage->pBt->usableSize - 4);
testcase( n==pPage->maxLocal );
testcase( n==pPage->maxLocal+1 );
if( n > pPage->maxLocal ) n = mn;
spaceLeft = n;
*pnSize = n + nHeader + 4;
pPrior = &pCell[nHeader+n];
pToRelease = 0;
pgnoOvfl = 0;
pBt = pPage->pBt;
/* At this point variables should be set as follows:
**
@@ -6296,8 +6306,35 @@ static int fillInCell(
#endif
/* Write the payload into the local Cell and any extra into overflow pages */
while( nPayload>0 ){
while( 1 ){
n = nPayload;
if( n>spaceLeft ) n = spaceLeft;
/* If pToRelease is not zero than pPayload points into the data area
** of pToRelease. Make sure pToRelease is still writeable. */
assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) );
/* If pPayload is part of the data area of pPage, then make sure pPage
** is still writeable */
assert( pPayload<pPage->aData || pPayload>=&pPage->aData[pBt->pageSize]
|| sqlite3PagerIswriteable(pPage->pDbPage) );
if( nSrc>=n ){
memcpy(pPayload, pSrc, n);
}else if( nSrc>0 ){
n = nSrc;
memcpy(pPayload, pSrc, n);
}else{
memset(pPayload, 0, n);
}
nPayload -= n;
if( nPayload<=0 ) break;
pPayload += n;
pSrc += n;
nSrc -= n;
spaceLeft -= n;
if( spaceLeft==0 ){
MemPage *pOvfl = 0;
#ifndef SQLITE_OMIT_AUTOVACUUM
Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */
if( pBt->autoVacuum ){
@@ -6350,30 +6387,6 @@ static int fillInCell(
pPayload = &pOvfl->aData[4];
spaceLeft = pBt->usableSize - 4;
}
n = nPayload;
if( n>spaceLeft ) n = spaceLeft;
/* If pToRelease is not zero than pPayload points into the data area
** of pToRelease. Make sure pToRelease is still writeable. */
assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) );
/* If pPayload is part of the data area of pPage, then make sure pPage
** is still writeable */
assert( pPayload<pPage->aData || pPayload>=&pPage->aData[pBt->pageSize]
|| sqlite3PagerIswriteable(pPage->pDbPage) );
if( nSrc>0 ){
if( n>nSrc ) n = nSrc;
assert( pSrc );
memcpy(pPayload, pSrc, n);
}else{
memset(pPayload, 0, n);
}
nPayload -= n;
pPayload += n;
pSrc += n;
nSrc -= n;
spaceLeft -= n;
}
releasePage(pToRelease);
return SQLITE_OK;