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Reduce the amount of memcpy() required by defragmentPage().

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FossilOrigin-Name: 3edab9957cc7bb90b52fd40b02613c2cb03fc166
This commit is contained in:
drh
2014-09-27 05:00:25 +00:00
parent 867db83159
commit 588400b861
3 changed files with 26 additions and 16 deletions
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25
src/btree.c
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@@ -1151,6 +1151,7 @@ static int defragmentPage(MemPage *pPage){
int nCell; /* Number of cells on the page */
unsigned char *data; /* The page data */
unsigned char *temp; /* Temp area for cell content */
unsigned char *src; /* Source of content */
int iCellFirst; /* First allowable cell index */
int iCellLast; /* Last possible cell index */
@@ -1160,15 +1161,13 @@ static int defragmentPage(MemPage *pPage){
assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE );
assert( pPage->nOverflow==0 );
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
temp = sqlite3PagerTempSpace(pPage->pBt->pPager);
data = pPage->aData;
temp = 0;
src = data = pPage->aData;
hdr = pPage->hdrOffset;
cellOffset = pPage->cellOffset;
nCell = pPage->nCell;
assert( nCell==get2byte(&data[hdr+3]) );
usableSize = pPage->pBt->usableSize;
cbrk = get2byte(&data[hdr+5]);
memcpy(&temp[cbrk], &data[cbrk], usableSize - cbrk);
cbrk = usableSize;
iCellFirst = cellOffset + 2*nCell;
iCellLast = usableSize - 4;
@@ -1187,7 +1186,7 @@ static int defragmentPage(MemPage *pPage){
}
#endif
assert( pc>=iCellFirst && pc<=iCellLast );
size = cellSizePtr(pPage, &temp[pc]);
size = cellSizePtr(pPage, &src[pc]);
cbrk -= size;
#if defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
if( cbrk<iCellFirst ){
@@ -1201,8 +1200,16 @@ static int defragmentPage(MemPage *pPage){
assert( cbrk+size<=usableSize && cbrk>=iCellFirst );
testcase( cbrk+size==usableSize );
testcase( pc+size==usableSize );
memcpy(&data[cbrk], &temp[pc], size);
put2byte(pAddr, cbrk);
if( temp==0 ){
int x;
if( cbrk==pc ) continue;
temp = sqlite3PagerTempSpace(pPage->pBt->pPager);
x = get2byte(&data[hdr+5]);
memcpy(&temp[x], &data[x], (cbrk+size) - x);
src = temp;
}
memcpy(&data[cbrk], &src[pc], size);
}
assert( cbrk>=iCellFirst );
put2byte(&data[hdr+5], cbrk);
@@ -5955,13 +5962,13 @@ static void assemblePage(
assert( pPage->nCell==0 );
assert( get2byteNotZero(&data[hdr+5])==nUsable );
pCellptr = &pPage->aCellIdx[nCell*2];
pCellptr = pPage->aCellIdx;
cellbody = nUsable;
for(i=nCell-1; i>=0; i--){
for(i=0; i<nCell; i++){
u16 sz = aSize[i];
pCellptr -= 2;
cellbody -= sz;
put2byte(pCellptr, cellbody);
pCellptr += 2;
memcpy(&data[cellbody], apCell[i], sz);
}
put2byte(&data[hdr+3], nCell);