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Add a new subclass for MemPage.xCellSize specifically for the case of a leaf

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page in a B+Tree, that is optimized for that cases.  This gains a half million
cycles or more at the cost of less than 200 bytes of code space.

FossilOrigin-Name: 7ad829224adbec5d74ff9e5ab040eb2ad3e17fe45da7a2cf0cca770a0731401a
This commit is contained in:
drh 2022-02-23 22:56:10 +00:00
parent 009a48e0ad
commit 19ae01be13
3 changed files with 62 additions and 15 deletions
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12
manifest
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@ -1,5 +1,5 @@
C Optimize\scalls\sto\sget2byte()\sin\sbtree.c\sfor\salmost\sa\sone-million\scycle\nperformance\sgain\sand\sa\sfew\sbytes\sless\scode.
D 2022-02-23T18:23:15.914
C Add\sa\snew\ssubclass\sfor\sMemPage.xCellSize\sspecifically\sfor\sthe\scase\sof\sa\sleaf\npage\sin\sa\sB+Tree,\sthat\sis\soptimized\sfor\sthat\scases.\s\sThis\sgains\sa\shalf\smillion\ncycles\sor\smore\sat\sthe\scost\sof\sless\sthan\s200\sbytes\sof\scode\sspace.
D 2022-02-23T22:56:10.399
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@ -492,7 +492,7 @@ F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
F src/backup.c a2891172438e385fdbe97c11c9745676bec54f518d4447090af97189fd8e52d7
F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
F src/btree.c 35870e7059b2b5bd90b0e1ac482b632b41a81dbb9b466bc7c9f3e4086571391c
F src/btree.c 50a8f846a1cad4e903aa31afe94df6ec329ac0cafba12977dcb7fc8b076a57d0
F src/btree.h 74d64b8f28cfa4a894d14d4ed64fa432cd697b98b61708d4351482ae15913e22
F src/btreeInt.h 7282a6e77775f93a6eb78d3a41dab372a01a4ec1d93d3b4728d191d15fda42e2
F src/build.c 9891c2160886cf7e344d7e8f1f7177f9612916c7c67ffeacd64cb34a92d387a8
@ -1944,8 +1944,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P ece326db50201937eb688809df39edc7fb97413b4614d2e2e783418192f7b02a
R 1c57a2dcd8f8c477175cc03c1d736930
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R 0695953d4b2e50c110a18d3aed9c37a6
U drh
Z 34e99039e8cc6255862cb2a477919b3e
Z dd86536eafbb7b97b20458522e864263
# Remove this line to create a well-formed Fossil manifest.

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@ -1 +1 @@
41061f29969dc546c2702f7f412127070a4dd54593827692df93a83c939dfb61
7ad829224adbec5d74ff9e5ab040eb2ad3e17fe45da7a2cf0cca770a0731401a

63
src/btree.c
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@ -1327,6 +1327,7 @@ static void btreeParseCell(
** the space used by the cell pointer.
**
** cellSizePtrNoPayload() => table internal nodes
** cellSizePtrTableLeaf() => table leaf nodes
** cellSizePtr() => all index nodes & table leaf nodes
*/
static u16 cellSizePtr(MemPage *pPage, u8 *pCell){
@ -1352,13 +1353,6 @@ static u16 cellSizePtr(MemPage *pPage, u8 *pCell){
}while( *(pIter)>=0x80 && pIter<pEnd );
}
pIter++;
if( pPage->intKey ){
/* pIter now points at the 64-bit integer key value, a variable length
** integer. The following block moves pIter to point at the first byte
** past the end of the key value. */
pEnd = &pIter[9];
while( (*pIter++)&0x80 && pIter<pEnd );
}
testcase( nSize==pPage->maxLocal );
testcase( nSize==(u32)pPage->maxLocal+1 );
if( nSize<=pPage->maxLocal ){
@ -1398,6 +1392,58 @@ static u16 cellSizePtrNoPayload(MemPage *pPage, u8 *pCell){
assert( debuginfo.nSize==(u16)(pIter - pCell) || CORRUPT_DB );
return (u16)(pIter - pCell);
}
static u16 cellSizePtrTableLeaf(MemPage *pPage, u8 *pCell){
u8 *pIter = pCell; /* For looping over bytes of pCell */
u8 *pEnd; /* End mark for a varint */
u32 nSize; /* Size value to return */
#ifdef SQLITE_DEBUG
/* The value returned by this function should always be the same as
** the (CellInfo.nSize) value found by doing a full parse of the
** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of
** this function verifies that this invariant is not violated. */
CellInfo debuginfo;
pPage->xParseCell(pPage, pCell, &debuginfo);
#endif
nSize = *pIter;
if( nSize>=0x80 ){
pEnd = &pIter[8];
nSize &= 0x7f;
do{
nSize = (nSize<<7) | (*++pIter & 0x7f);
}while( *(pIter)>=0x80 && pIter<pEnd );
}
pIter++;
/* pIter now points at the 64-bit integer key value, a variable length
** integer. The following block moves pIter to point at the first byte
** past the end of the key value. */
if( (*pIter++)&0x80
&& (*pIter++)&0x80
&& (*pIter++)&0x80
&& (*pIter++)&0x80
&& (*pIter++)&0x80
&& (*pIter++)&0x80
&& (*pIter++)&0x80
&& (*pIter++)&0x80 ){ pIter++; }
testcase( nSize==pPage->maxLocal );
testcase( nSize==(u32)pPage->maxLocal+1 );
if( nSize<=pPage->maxLocal ){
nSize += (u32)(pIter - pCell);
if( nSize<4 ) nSize = 4;
}else{
int minLocal = pPage->minLocal;
nSize = minLocal + (nSize - minLocal) % (pPage->pBt->usableSize - 4);
testcase( nSize==pPage->maxLocal );
testcase( nSize==(u32)pPage->maxLocal+1 );
if( nSize>pPage->maxLocal ){
nSize = minLocal;
}
nSize += 4 + (u16)(pIter - pCell);
}
assert( nSize==debuginfo.nSize || CORRUPT_DB );
return (u16)nSize;
}
#ifdef SQLITE_DEBUG
@ -1880,6 +1926,7 @@ static int decodeFlags(MemPage *pPage, int flagByte){
pPage->intKey = 1;
if( pPage->leaf ){
pPage->intKeyLeaf = 1;
pPage->xCellSize = cellSizePtrTableLeaf;
pPage->xParseCell = btreeParseCellPtr;
}else{
pPage->intKeyLeaf = 0;
@ -9310,7 +9357,7 @@ int sqlite3BtreeDelete(BtCursor *pCur, u8 flags){
bPreserve = (flags & BTREE_SAVEPOSITION)!=0;
if( bPreserve ){
if( !pPage->leaf
|| (pPage->nFree+cellSizePtr(pPage,pCell)+2)>(int)(pBt->usableSize*2/3)
|| (pPage->nFree+pPage->xCellSize(pPage,pCell)+2)>(int)(pBt->usableSize*2/3)
|| pPage->nCell==1 /* See dbfuzz001.test for a test case */
){
/* A b-tree rebalance will be required after deleting this entry.