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Simplification to the getAndInitPage() routine that results in improved

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performance.

FossilOrigin-Name: 2e9734c2335d8c06fedc9f4cca02baaf326f7fa276bd464f3214f383715a48d6
This commit is contained in:
drh
2023-06-22 01:03:39 +00:00
parent 71aac8763f
commit d4170ac0eb
3 changed files with 66 additions and 58 deletions
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110
src/btree.c
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@@ -2318,69 +2318,41 @@ Pgno sqlite3BtreeLastPage(Btree *p){
/*
** Get a page from the pager and initialize it.
**
** If pCur!=0 then the page is being fetched as part of a moveToChild()
** call. Do additional sanity checking on the page in this case.
** And if that additional sanity checking fails, adjust the state of
** the cursor so that the fetch is effectively "undone".
**
** 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 */
BtCursor *pCur, /* Cursor to receive the page, or NULL */
int bReadOnly /* True for a read-only page */
){
int rc;
DbPage *pDbPage;
MemPage *pPage;
assert( sqlite3_mutex_held(pBt->mutex) );
assert( pCur==0 || ppPage==&pCur->pPage );
assert( pCur==0 || bReadOnly==pCur->curPagerFlags );
assert( pCur==0 || pCur->iPage>0 );
if( pgno>btreePagecount(pBt) ){
rc = SQLITE_CORRUPT_BKPT;
goto getAndInitPage_error1;
*ppPage = 0;
return SQLITE_CORRUPT_BKPT;
}
rc = sqlite3PagerGet(pBt->pPager, pgno, (DbPage**)&pDbPage, bReadOnly);
if( rc ){
goto getAndInitPage_error1;
*ppPage = 0;
return rc;
}
*ppPage = (MemPage*)sqlite3PagerGetExtra(pDbPage);
if( (*ppPage)->isInit==0 ){
pPage = (MemPage*)sqlite3PagerGetExtra(pDbPage);
if( pPage->isInit==0 ){
btreePageFromDbPage(pDbPage, pgno, pBt);
rc = btreeInitPage(*ppPage);
rc = btreeInitPage(pPage);
if( rc!=SQLITE_OK ){
goto getAndInitPage_error2;
releasePage(pPage);
*ppPage = 0;
return rc;
}
}
assert( (*ppPage)->pgno==pgno || CORRUPT_DB );
assert( (*ppPage)->aData==sqlite3PagerGetData(pDbPage) );
/* If obtaining a child page for a cursor, we must verify that the page is
** compatible with the root page. */
if( pCur && ((*ppPage)->nCell<1 || (*ppPage)->intKey!=pCur->curIntKey) ){
rc = SQLITE_CORRUPT_PGNO(pgno);
goto getAndInitPage_error2;
}
assert( pPage->pgno==pgno || CORRUPT_DB );
assert( pPage->aData==sqlite3PagerGetData(pDbPage) );
*ppPage = pPage;
return SQLITE_OK;
getAndInitPage_error2:
releasePage(*ppPage);
getAndInitPage_error1:
if( pCur ){
pCur->iPage--;
pCur->pPage = pCur->apPage[pCur->iPage];
}
testcase( pgno==0 );
assert( pgno!=0 || rc!=SQLITE_OK );
return rc;
}
/*
@@ -5354,6 +5326,7 @@ const void *sqlite3BtreePayloadFetch(BtCursor *pCur, u32 *pAmt){
** vice-versa).
*/
static int moveToChild(BtCursor *pCur, u32 newPgno){
int rc;
assert( cursorOwnsBtShared(pCur) );
assert( pCur->eState==CURSOR_VALID );
assert( pCur->iPage<BTCURSOR_MAX_DEPTH );
@@ -5367,8 +5340,17 @@ static int moveToChild(BtCursor *pCur, u32 newPgno){
pCur->apPage[pCur->iPage] = pCur->pPage;
pCur->ix = 0;
pCur->iPage++;
return getAndInitPage(pCur->pBt, newPgno, &pCur->pPage, pCur,
pCur->curPagerFlags);
rc = getAndInitPage(pCur->pBt, newPgno, &pCur->pPage, pCur->curPagerFlags);
if( rc==SQLITE_OK
&& (pCur->pPage->nCell<1 || pCur->pPage->intKey!=pCur->curIntKey)
){
releasePage(pCur->pPage);
rc = SQLITE_CORRUPT_PGNO(newPgno);
}
if( rc ){
pCur->pPage = pCur->apPage[--pCur->iPage];
}
return rc;
}
#ifdef SQLITE_DEBUG
@@ -5475,7 +5457,7 @@ static int moveToRoot(BtCursor *pCur){
sqlite3BtreeClearCursor(pCur);
}
rc = getAndInitPage(pCur->pBt, pCur->pgnoRoot, &pCur->pPage,
0, pCur->curPagerFlags);
pCur->curPagerFlags);
if( rc!=SQLITE_OK ){
pCur->eState = CURSOR_INVALID;
return rc;
@@ -6088,10 +6070,36 @@ bypass_moveto_root:
}else{
chldPg = get4byte(findCell(pPage, lwr));
}
pCur->ix = (u16)lwr;
rc = moveToChild(pCur, chldPg);
if( rc ) break;
}
/* This block is similar to an in-lined version of:
**
** pCur->ix = (u16)lwr;
** rc = moveToChild(pCur, chldPg);
** if( rc ) break;
*/
pCur->info.nSize = 0;
pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
if( pCur->iPage>=(BTCURSOR_MAX_DEPTH-1) ){
return SQLITE_CORRUPT_BKPT;
}
pCur->aiIdx[pCur->iPage] = (u16)lwr;
pCur->apPage[pCur->iPage] = pCur->pPage;
pCur->ix = 0;
pCur->iPage++;
rc = getAndInitPage(pCur->pBt, chldPg, &pCur->pPage, pCur->curPagerFlags);
if( rc==SQLITE_OK
&& (pCur->pPage->nCell<1 || pCur->pPage->intKey!=pCur->curIntKey)
){
releasePage(pCur->pPage);
rc = SQLITE_CORRUPT_PGNO(chldPg);
}
if( rc ){
pCur->pPage = pCur->apPage[--pCur->iPage];
break;
}
/*
***** End of in-lined moveToChild() call */
}
moveto_index_finish:
pCur->info.nSize = 0;
assert( (pCur->curFlags & BTCF_ValidOvfl)==0 );
@@ -8145,7 +8153,7 @@ static int balance_nonroot(
pgno = get4byte(pRight);
while( 1 ){
if( rc==SQLITE_OK ){
rc = getAndInitPage(pBt, pgno, &apOld[i], 0, 0);
rc = getAndInitPage(pBt, pgno, &apOld[i], 0);
}
if( rc ){
memset(apOld, 0, (i+1)*sizeof(MemPage*));
@@ -10030,7 +10038,7 @@ static int clearDatabasePage(
if( pgno>btreePagecount(pBt) ){
return SQLITE_CORRUPT_BKPT;
}
rc = getAndInitPage(pBt, pgno, &pPage, 0, 0);
rc = getAndInitPage(pBt, pgno, &pPage, 0);
if( rc ) return rc;
if( (pBt->openFlags & BTREE_SINGLE)==0
&& sqlite3PagerPageRefcount(pPage->pDbPage) != (1 + (pgno==1))