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Performance improvements in moveToChild() by shifting some work over

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to getAndInitPage().  Net improvement is about 800K cycles at cost of 30 bytes.

FossilOrigin-Name: 1956a4ce8eca650d98a7f68fd2d82eb8a3d6069f
This commit is contained in:
drh
2015-06-27 19:45:03 +00:00
parent 375beb0ec0
commit 28f58dd60e
4 changed files with 58 additions and 41 deletions
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82
src/btree.c
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@@ -1909,40 +1909,63 @@ u32 sqlite3BtreeLastPage(Btree *p){
}
/*
** Get a page from the pager and initialize it. This routine is just a
** convenience wrapper around separate calls to btreeGetPage() and
** btreeInitPage().
** Get a page from the pager and initialize it.
**
** If an error occurs, then the value *ppPage is set to is undefined. It
** If pCur!=0 then the page acquired will be added to that cursor.
** If the fetch fails, this routine must decrement pCur->iPage.
**
** The page is fetched as read-write unless pCur is not NULL and is
** a read-only cursor.
**
** If an error occurs, then *ppPage is undefined. It
** may remain unchanged, or it may be set to an invalid value.
*/
static int getAndInitPage(
BtShared *pBt, /* The database file */
Pgno pgno, /* Number of the page to get */
MemPage **ppPage, /* Write the page pointer here */
int bReadonly /* PAGER_GET_READONLY or 0 */
BtCursor *pCur, /* Cursor to receive the page, or NULL */
int bReadOnly /* True for a read-only page */
){
int rc;
DbPage *pDbPage;
assert( sqlite3_mutex_held(pBt->mutex) );
assert( bReadonly==PAGER_GET_READONLY || bReadonly==0 );
assert( pCur==0 || ppPage==&pCur->apPage[pCur->iPage] );
assert( pCur==0 || bReadOnly==pCur->curPagerFlags );
if( pgno>btreePagecount(pBt) ){
rc = SQLITE_CORRUPT_BKPT;
}else{
DbPage *pDbPage;
rc = sqlite3PagerAcquire(pBt->pPager, pgno, (DbPage**)&pDbPage, bReadonly);
if( rc ) return rc;
*ppPage = btreePageFromDbPage(pDbPage, pgno, pBt);
if( (*ppPage)->isInit==0 ){
rc = btreeInitPage(*ppPage);
if( rc!=SQLITE_OK ){
releasePage(*ppPage);
}
goto getAndInitPage_error;
}
rc = sqlite3PagerAcquire(pBt->pPager, pgno, (DbPage**)&pDbPage, bReadOnly);
if( rc ){
goto getAndInitPage_error;
}
*ppPage = btreePageFromDbPage(pDbPage, pgno, pBt);
if( (*ppPage)->isInit==0 ){
rc = btreeInitPage(*ppPage);
if( rc!=SQLITE_OK ){
releasePage(*ppPage);
goto getAndInitPage_error;
}
}
/* If obtaining a page for a cursor, we must verify that the page is
** compatible with the cursor */
if( pCur && pCur->iPage>0
&& ((*ppPage)->nCell<1 || (*ppPage)->intKey!=pCur->apPage[0]->intKey)
){
rc = SQLITE_CORRUPT_BKPT;
releasePage(*ppPage);
goto getAndInitPage_error;
}
testcase( pgno==0 );
assert( pgno!=0 || rc==SQLITE_CORRUPT );
return SQLITE_OK;
getAndInitPage_error:
if( pCur ) pCur->iPage--;
return rc;
}
@@ -4028,6 +4051,7 @@ static int btreeCursor(
pCur->pBt = pBt;
assert( wrFlag==0 || wrFlag==BTCF_WriteFlag );
pCur->curFlags = wrFlag;
pCur->curPagerFlags = wrFlag ? 0 : PAGER_GET_READONLY;
pCur->pNext = pBt->pCursor;
if( pCur->pNext ){
pCur->pNext->pPrev = pCur;
@@ -4641,9 +4665,6 @@ const void *sqlite3BtreeDataFetch(BtCursor *pCur, u32 *pAmt){
** vice-versa).
*/
static int moveToChild(BtCursor *pCur, u32 newPgno){
int rc;
int i = pCur->iPage;
MemPage *pNewPage;
BtShared *pBt = pCur->pBt;
assert( cursorHoldsMutex(pCur) );
@@ -4653,19 +4674,12 @@ static int moveToChild(BtCursor *pCur, u32 newPgno){
if( pCur->iPage>=(BTCURSOR_MAX_DEPTH-1) ){
return SQLITE_CORRUPT_BKPT;
}
rc = getAndInitPage(pBt, newPgno, &pNewPage,
(pCur->curFlags & BTCF_WriteFlag)==0 ? PAGER_GET_READONLY : 0);
if( rc ) return rc;
pCur->apPage[i+1] = pNewPage;
pCur->aiIdx[i+1] = 0;
pCur->iPage++;
pCur->info.nSize = 0;
pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
if( pNewPage->nCell<1 || pNewPage->intKey!=pCur->apPage[i]->intKey ){
return SQLITE_CORRUPT_BKPT;
}
return SQLITE_OK;
pCur->iPage++;
pCur->aiIdx[pCur->iPage] = 0;
return getAndInitPage(pBt, newPgno, &pCur->apPage[pCur->iPage],
pCur, pCur->curPagerFlags);
}
#if SQLITE_DEBUG
@@ -4760,8 +4774,10 @@ static int moveToRoot(BtCursor *pCur){
pCur->eState = CURSOR_INVALID;
return SQLITE_OK;
}else{
assert( pCur->iPage==(-1) );
pCur->iPage = 0;
rc = getAndInitPage(pCur->pBtree->pBt, pCur->pgnoRoot, &pCur->apPage[0],
(pCur->curFlags & BTCF_WriteFlag)==0 ? PAGER_GET_READONLY : 0);
pCur, pCur->curPagerFlags);
if( rc!=SQLITE_OK ){
pCur->eState = CURSOR_INVALID;
return rc;
@@ -6963,7 +6979,7 @@ static int balance_nonroot(
}
pgno = get4byte(pRight);
while( 1 ){
rc = getAndInitPage(pBt, pgno, &apOld[i], 0);
rc = getAndInitPage(pBt, pgno, &apOld[i], 0, 0);
if( rc ){
memset(apOld, 0, (i+1)*sizeof(MemPage*));
goto balance_cleanup;
@@ -8280,7 +8296,7 @@ static int clearDatabasePage(
if( pgno>btreePagecount(pBt) ){
return SQLITE_CORRUPT_BKPT;
}
rc = getAndInitPage(pBt, pgno, &pPage, 0);
rc = getAndInitPage(pBt, pgno, &pPage, 0, 0);
if( rc ) return rc;
if( pPage->bBusy ){
rc = SQLITE_CORRUPT_BKPT;