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Size and performance optimization to dropCell() and freeSpace().

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FossilOrigin-Name: bc1ec123ce05c9d16b0942f870381145dc9725764e47806939ff207a73066f4d
This commit is contained in:
drh
2017-08-23 20:36:06 +00:00
parent 5e27e1dc49
commit 5e398e4cbd
3 changed files with 24 additions and 22 deletions
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32
src/btree.c
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@@ -1505,7 +1505,7 @@ static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
if( (x = size - nByte)>=0 ){
testcase( x==4 );
testcase( x==3 );
if( pc < pPg->cellOffset+2*pPg->nCell || size+pc > usableSize ){
if( size+pc > usableSize ){
*pRc = SQLITE_CORRUPT_PGNO(pPg->pgno);
return 0;
}else if( x<4 ){
@@ -1640,7 +1640,7 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
u8 hdr; /* Page header size. 0 or 100 */
u8 nFrag = 0; /* Reduction in fragmentation */
u16 iOrigSize = iSize; /* Original value of iSize */
u32 iLast = pPage->pBt->usableSize-4; /* Largest possible freeblock offset */
u16 x; /* Offset to cell content area */
u32 iEnd = iStart + iSize; /* First byte past the iStart buffer */
unsigned char *data = pPage->aData; /* Page content */
@@ -1650,13 +1650,7 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
assert( CORRUPT_DB || iEnd <= pPage->pBt->usableSize );
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
assert( iSize>=4 ); /* Minimum cell size is 4 */
assert( iStart<=iLast );
/* Overwrite deleted information with zeros when the secure_delete
** option is enabled */
if( pPage->pBt->btsFlags & BTS_FAST_SECURE ){
memset(&data[iStart], 0, iSize);
}
assert( iStart<=pPage->pBt->usableSize-4 );
/* The list of freeblocks must be in ascending order. Find the
** spot on the list where iStart should be inserted.
@@ -1673,7 +1667,9 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
}
iPtr = iFreeBlk;
}
if( iFreeBlk>iLast ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
if( iFreeBlk>pPage->pBt->usableSize-4 ){
return SQLITE_CORRUPT_PGNO(pPage->pgno);
}
assert( iFreeBlk>iPtr || iFreeBlk==0 );
/* At this point:
@@ -1709,19 +1705,25 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
if( nFrag>data[hdr+7] ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
data[hdr+7] -= nFrag;
}
if( iStart==get2byte(&data[hdr+5]) ){
x = get2byte(&data[hdr+5]);
if( iStart<=x ){
/* The new freeblock is at the beginning of the cell content area,
** so just extend the cell content area rather than create another
** freelist entry */
if( iPtr!=hdr+1 ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
if( iStart<x || iPtr!=hdr+1 ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
put2byte(&data[hdr+1], iFreeBlk);
put2byte(&data[hdr+5], iEnd);
}else{
/* Insert the new freeblock into the freelist */
put2byte(&data[iPtr], iStart);
put2byte(&data[iStart], iFreeBlk);
put2byte(&data[iStart+2], iSize);
}
if( pPage->pBt->btsFlags & BTS_FAST_SECURE ){
/* Overwrite deleted information with zeros when the secure_delete
** option is enabled */
memset(&data[iStart], 0, iSize);
}
put2byte(&data[iStart], iFreeBlk);
put2byte(&data[iStart+2], iSize);
pPage->nFree += iOrigSize;
return SQLITE_OK;
}
@@ -6418,7 +6420,7 @@ static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){
hdr = pPage->hdrOffset;
testcase( pc==get2byte(&data[hdr+5]) );
testcase( pc+sz==pPage->pBt->usableSize );
if( pc < (u32)get2byte(&data[hdr+5]) || pc+sz > pPage->pBt->usableSize ){
if( pc+sz > pPage->pBt->usableSize ){
*pRC = SQLITE_CORRUPT_BKPT;
return;
}