database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-08-07 02:42:48 +03:00
Code Activity

Micro-optimizations in sqlite3BtreeNext() and sqlite3BtreePrevious().

Browse Source 
FossilOrigin-Name: 839c7996eecd5480152c514555b9aa1121a69ce0
This commit is contained in:
drh
2014-09-01 13:29:32 +00:00
parent 31970cca38
commit ee6438df0b
3 changed files with 84 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

123
src/btree.c
View File

@@ -4513,17 +4513,16 @@ static int moveToRightmost(BtCursor *pCur){
assert( cursorHoldsMutex(pCur) );
assert( pCur->eState==CURSOR_VALID );
while( rc==SQLITE_OK && !(pPage = pCur->apPage[pCur->iPage])->leaf ){
while( !(pPage = pCur->apPage[pCur->iPage])->leaf ){
pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
pCur->aiIdx[pCur->iPage] = pPage->nCell;
rc = moveToChild(pCur, pgno);
if( rc ) return rc;
}
if( rc==SQLITE_OK ){
pCur->aiIdx[pCur->iPage] = pPage->nCell-1;
pCur->info.nSize = 0;
pCur->curFlags &= ~BTCF_ValidNKey;
}
return rc;
pCur->aiIdx[pCur->iPage] = pPage->nCell-1;
assert( pCur->info.nSize==0 );
assert( (pCur->curFlags & BTCF_ValidNKey)==0 );
return SQLITE_OK;
}
/* Move the cursor to the first entry in the table. Return SQLITE_OK
@@ -4843,6 +4842,12 @@ int sqlite3BtreeEof(BtCursor *pCur){
** was already pointing to the last entry in the database before
** this routine was called, then set *pRes=1.
**
** The main entry point is sqlite3BtreeNext(). That routine is optimized
** for the common case of merely incrementing the cell counter BtCursor.aiIdx
** to the next cell on the current page. The (slower) btreeNext() helper
** routine is called when it is necessary to move to a different page or
** to restore the cursor.
**
** The calling function will set *pRes to 0 or 1. The initial *pRes value
** will be 1 if the cursor being stepped corresponds to an SQL index and
** if this routine could have been skipped if that SQL index had been
@@ -4852,20 +4857,18 @@ int sqlite3BtreeEof(BtCursor *pCur){
** SQLite btree implementation does not. (Note that the comdb2 btree
** implementation does use this hint, however.)
*/
int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
static SQLITE_NOINLINE int btreeNext(BtCursor *pCur, int *pRes){
int rc;
int idx;
MemPage *pPage;
assert( cursorHoldsMutex(pCur) );
assert( pRes!=0 );
assert( *pRes==0 || *pRes==1 );
assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
assert( *pRes==0 );
if( pCur->eState!=CURSOR_VALID ){
invalidateOverflowCache(pCur);
assert( (pCur->curFlags & BTCF_ValidOvfl)==0 );
rc = restoreCursorPosition(pCur);
if( rc!=SQLITE_OK ){
*pRes = 0;
return rc;
}
if( CURSOR_INVALID==pCur->eState ){
@@ -4877,7 +4880,6 @@ int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
pCur->eState = CURSOR_VALID;
if( pCur->skipNext>0 ){
pCur->skipNext = 0;
*pRes = 0;
return SQLITE_OK;
}
pCur->skipNext = 0;
@@ -4895,18 +4897,11 @@ int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
** page into more than one b-tree structure. */
testcase( idx>pPage->nCell );
pCur->info.nSize = 0;
pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
if( idx>=pPage->nCell ){
if( !pPage->leaf ){
rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
if( rc ){
*pRes = 0;
return rc;
}
rc = moveToLeftmost(pCur);
*pRes = 0;
return rc;
if( rc ) return rc;
return moveToLeftmost(pCur);
}
do{
if( pCur->iPage==0 ){
@@ -4917,22 +4912,39 @@ int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
moveToParent(pCur);
pPage = pCur->apPage[pCur->iPage];
}while( pCur->aiIdx[pCur->iPage]>=pPage->nCell );
*pRes = 0;
if( pPage->intKey ){
rc = sqlite3BtreeNext(pCur, pRes);
return sqlite3BtreeNext(pCur, pRes);
}else{
rc = SQLITE_OK;
return SQLITE_OK;
}
return rc;
}
*pRes = 0;
if( pPage->leaf ){
return SQLITE_OK;
}else{
return moveToLeftmost(pCur);
}
}
int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
MemPage *pPage;
assert( cursorHoldsMutex(pCur) );
assert( pRes!=0 );
assert( *pRes==0 || *pRes==1 );
assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
pCur->info.nSize = 0;
pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
*pRes = 0;
if( pCur->eState!=CURSOR_VALID ) return btreeNext(pCur, pRes);
pPage = pCur->apPage[pCur->iPage];
if( (++pCur->aiIdx[pCur->iPage])>=pPage->nCell ){
pCur->aiIdx[pCur->iPage]--;
return btreeNext(pCur, pRes);
}
if( pPage->leaf ){
return SQLITE_OK;
}else{
return moveToLeftmost(pCur);
}
rc = moveToLeftmost(pCur);
return rc;
}
/*
** Step the cursor to the back to the previous entry in the database. If
@@ -4940,6 +4952,12 @@ int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
** was already pointing to the first entry in the database before
** this routine was called, then set *pRes=1.
**
** The main entry point is sqlite3BtreePrevious(). That routine is optimized
** for the common case of merely decrementing the cell counter BtCursor.aiIdx
** to the previous cell on the current page. The (slower) btreePrevious() helper
** routine is called when it is necessary to move to a different page or
** to restore the cursor.
**
** The calling function will set *pRes to 0 or 1. The initial *pRes value
** will be 1 if the cursor being stepped corresponds to an SQL index and
** if this routine could have been skipped if that SQL index had been
@@ -4949,22 +4967,21 @@ int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
** SQLite btree implementation does not. (Note that the comdb2 btree
** implementation does use this hint, however.)
*/
int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
static SQLITE_NOINLINE int btreePrevious(BtCursor *pCur, int *pRes){
int rc;
MemPage *pPage;
assert( cursorHoldsMutex(pCur) );
assert( pRes!=0 );
assert( *pRes==0 || *pRes==1 );
assert( *pRes==0 );
assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
pCur->curFlags &= ~(BTCF_AtLast|BTCF_ValidOvfl);
assert( (pCur->curFlags & (BTCF_AtLast|BTCF_ValidOvfl|BTCF_ValidNKey))==0 );
assert( pCur->info.nSize==0 );
if( pCur->eState!=CURSOR_VALID ){
if( ALWAYS(pCur->eState>=CURSOR_REQUIRESEEK) ){
rc = btreeRestoreCursorPosition(pCur);
if( rc!=SQLITE_OK ){
*pRes = 0;
return rc;
}
assert( pCur->eState>=CURSOR_REQUIRESEEK );
rc = btreeRestoreCursorPosition(pCur);
if( rc!=SQLITE_OK ){
return rc;
}
if( CURSOR_INVALID==pCur->eState ){
*pRes = 1;
@@ -4975,7 +4992,6 @@ int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
pCur->eState = CURSOR_VALID;
if( pCur->skipNext<0 ){
pCur->skipNext = 0;
*pRes = 0;
return SQLITE_OK;
}
pCur->skipNext = 0;
@@ -4987,10 +5003,7 @@ int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
if( !pPage->leaf ){
int idx = pCur->aiIdx[pCur->iPage];
rc = moveToChild(pCur, get4byte(findCell(pPage, idx)));
if( rc ){
*pRes = 0;
return rc;
}
if( rc ) return rc;
rc = moveToRightmost(pCur);
}else{
while( pCur->aiIdx[pCur->iPage]==0 ){
@@ -5001,8 +5014,8 @@ int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
}
moveToParent(pCur);
}
pCur->info.nSize = 0;
pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
assert( pCur->info.nSize==0 );
assert( (pCur->curFlags & (BTCF_ValidNKey|BTCF_ValidOvfl))==0 );
pCur->aiIdx[pCur->iPage]--;
pPage = pCur->apPage[pCur->iPage];
@@ -5012,9 +5025,25 @@ int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
rc = SQLITE_OK;
}
}
*pRes = 0;
return rc;
}
int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
assert( cursorHoldsMutex(pCur) );
assert( pRes!=0 );
assert( *pRes==0 || *pRes==1 );
assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
*pRes = 0;
pCur->curFlags &= ~(BTCF_AtLast|BTCF_ValidOvfl|BTCF_ValidNKey);
pCur->info.nSize = 0;
if( pCur->eState!=CURSOR_VALID
|| pCur->aiIdx[pCur->iPage]==0
|| pCur->apPage[pCur->iPage]->leaf==0
){
return btreePrevious(pCur, pRes);
}
pCur->aiIdx[pCur->iPage]--;
return SQLITE_OK;
}
/*
** Allocate a new page from the database file.