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Performance improvements in btreeParseCell() by inlining the varint decoder.

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FossilOrigin-Name: faab0ed928074f3ec7c25e1a2058414fbd9b013c
This commit is contained in:
drh
2015-06-19 18:24:37 +00:00
parent 5fa605142f
commit 56cb04efc8
3 changed files with 51 additions and 9 deletions
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43
src/btree.c
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@@ -1054,6 +1054,7 @@ static void btreeParseCellPtr(
){
u8 *pIter; /* For scanning through pCell */
u32 nPayload; /* Number of bytes of cell payload */
u64 iKey; /* Extracted Key value */
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
assert( pPage->leaf==0 || pPage->leaf==1 );
@@ -1061,8 +1062,46 @@ static void btreeParseCellPtr(
assert( pPage->noPayload==0 );
assert( pPage->intKeyLeaf );
assert( pPage->childPtrSize==0 );
pIter = pCell + getVarint32(pCell, nPayload);
pIter += getVarint(pIter, (u64*)&pInfo->nKey);
pIter = pCell;
/* The next block of code is equivalent to:
**
** pIter += getVarint32(pIter, nPayload);
**
** The code is inlined to avoid a function call.
*/
nPayload = *pIter;
if( nPayload>=0x80 ){
u8 *pEnd = &pIter[9];
nPayload &= 0x7f;
do{
nPayload = (nPayload<<7) | (*++pIter & 0x7f);
}while( (*pIter)>=0x80 && pIter<pEnd );
}
pIter++;
/* The next block of code is equivalent to:
**
** pIter += getVarint(pIter, (u64*)&pInfo->nKey);
**
** The code is inlined to avoid a function call.
*/
iKey = *pIter;
if( iKey>=0x80 ){
u8 *pEnd = &pIter[7];
iKey &= 0x7f;
while(1){
iKey = (iKey<<7) | (*++pIter & 0x7f);
if( (*pIter)<0x80 ) break;
if( pIter>=pEnd ){
iKey = (iKey<<8) | *++pIter;
break;
}
}
}
pIter++;
pInfo->nKey = *(i64*)&iKey;
pInfo->nPayload = nPayload;
pInfo->pPayload = pIter;
testcase( nPayload==pPage->maxLocal );