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Allow read-only cursors to use mmap pages even if there is an open write transaction.

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FossilOrigin-Name: b387e2f9d24dccac1fd040e309f6fc7ec1cfffba
This commit is contained in:
dan
2013-03-15 18:29:18 +00:00
parent b2d3de3bf4
commit 11dcd11913
5 changed files with 124 additions and 76 deletions
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100
src/btree.c
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@@ -1569,13 +1569,17 @@ static int btreeGetPage(
BtShared *pBt, /* The btree */
Pgno pgno, /* Number of the page to fetch */
MemPage **ppPage, /* Return the page in this parameter */
int noContent /* Do not load page content if true */
int noContent, /* Do not load page content if true */
int bReadonly /* True if a read-only (mmap) page is ok */
){
int rc;
DbPage *pDbPage;
int flags = (noContent ? PAGER_ACQUIRE_NOCONTENT : 0)
| (bReadonly ? PAGER_ACQUIRE_READONLY : 0);
assert( noContent==0 || bReadonly==0 );
assert( sqlite3_mutex_held(pBt->mutex) );
rc = sqlite3PagerAcquire(pBt->pPager, pgno, (DbPage**)&pDbPage, noContent);
rc = sqlite3PagerAcquire(pBt->pPager, pgno, (DbPage**)&pDbPage, flags);
if( rc ) return rc;
*ppPage = btreePageFromDbPage(pDbPage, pgno, pBt);
return SQLITE_OK;
@@ -1618,9 +1622,10 @@ u32 sqlite3BtreeLastPage(Btree *p){
** 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 */
BtShared *pBt, /* The database file */
Pgno pgno, /* Number of the page to get */
MemPage **ppPage, /* Write the page pointer here */
int bReadonly /* True if a read-only (mmap) page is ok */
){
int rc;
assert( sqlite3_mutex_held(pBt->mutex) );
@@ -1628,7 +1633,7 @@ static int getAndInitPage(
if( pgno>btreePagecount(pBt) ){
rc = SQLITE_CORRUPT_BKPT;
}else{
rc = btreeGetPage(pBt, pgno, ppPage, 0);
rc = btreeGetPage(pBt, pgno, ppPage, 0, bReadonly);
if( rc==SQLITE_OK ){
rc = btreeInitPage(*ppPage);
if( rc!=SQLITE_OK ){
@@ -2350,7 +2355,7 @@ static int lockBtree(BtShared *pBt){
assert( pBt->pPage1==0 );
rc = sqlite3PagerSharedLock(pBt->pPager);
if( rc!=SQLITE_OK ) return rc;
rc = btreeGetPage(pBt, 1, &pPage1, 0);
rc = btreeGetPage(pBt, 1, &pPage1, 0, 0);
if( rc!=SQLITE_OK ) return rc;
/* Do some checking to help insure the file we opened really is
@@ -2565,31 +2570,30 @@ int sqlite3BtreeNewDb(Btree *p){
}
/*
** If the shared-btree passed as the only argument is holding references
** to mmap pages, replace them with read/write pages. Return SQLITE_OK
** if successful, or an error code otherwise.
** Ensure that any root page references held by open cursors are not
** mmap pages.
*/
static int btreeSwapOutMmap(BtShared *pBt){
BtCursor *pCsr;
for(pCsr=pBt->pCursor; pCsr; pCsr=pCsr->pNext){
int i;
for(i=0; i<=pCsr->iPage; i++){
MemPage *pPg = pCsr->apPage[i];
int rc = SQLITE_OK; /* Return code */
BtCursor *pCsr; /* Used to iterate through all open cursors */
for(pCsr=pBt->pCursor; pCsr && rc==SQLITE_OK; pCsr=pCsr->pNext){
if( pCsr->iPage>=0 ){
MemPage *pPg = pCsr->apPage[0];
if( pPg->pDbPage->flags & PGHDR_MMAP ){
int rc;
MemPage *pNew = 0;
rc = btreeGetPage(pBt, pPg->pgno, &pNew, 0);
if( rc==SQLITE_OK && i==pCsr->iPage ){
rc = btreeGetPage(pBt, pPg->pgno, &pNew, 0, 0);
if( rc==SQLITE_OK && pCsr->iPage==0 ){
pCsr->info.pCell = pNew->aData + (pCsr->info.pCell - pPg->aData);
}
pCsr->apPage[i] = pNew;
pCsr->apPage[0] = pNew;
releasePage(pPg);
if( rc!=SQLITE_OK ) return rc;
}
}
}
return SQLITE_OK;
return rc;
}
/*
@@ -2940,7 +2944,7 @@ static int relocatePage(
** iPtrPage.
*/
if( eType!=PTRMAP_ROOTPAGE ){
rc = btreeGetPage(pBt, iPtrPage, &pPtrPage, 0);
rc = btreeGetPage(pBt, iPtrPage, &pPtrPage, 0, 0);
if( rc!=SQLITE_OK ){
return rc;
}
@@ -3024,7 +3028,7 @@ static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg, int bCommit){
u8 eMode = BTALLOC_ANY; /* Mode parameter for allocateBtreePage() */
Pgno iNear = 0; /* nearby parameter for allocateBtreePage() */
rc = btreeGetPage(pBt, iLastPg, &pLastPg, 0);
rc = btreeGetPage(pBt, iLastPg, &pLastPg, 0, 0);
if( rc!=SQLITE_OK ){
return rc;
}
@@ -3116,8 +3120,11 @@ int sqlite3BtreeIncrVacuum(Btree *p){
if( nOrig<nFin ){
rc = SQLITE_CORRUPT_BKPT;
}else if( nFree>0 ){
invalidateAllOverflowCache(pBt);
rc = incrVacuumStep(pBt, nFin, nOrig, 0);
rc = saveAllCursors(pBt, 0, 0);
if( rc==SQLITE_OK ){
invalidateAllOverflowCache(pBt);
rc = incrVacuumStep(pBt, nFin, nOrig, 0);
}
if( rc==SQLITE_OK ){
rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
put4byte(&pBt->pPage1->aData[28], pBt->nPage);
@@ -3438,7 +3445,7 @@ int sqlite3BtreeRollback(Btree *p, int tripCode){
/* The rollback may have destroyed the pPage1->aData value. So
** call btreeGetPage() on page 1 again to make
** sure pPage1->aData is set correctly. */
if( btreeGetPage(pBt, 1, &pPage1, 0)==SQLITE_OK ){
if( btreeGetPage(pBt, 1, &pPage1, 0, 0)==SQLITE_OK ){
int nPage = get4byte(28+(u8*)pPage1->aData);
testcase( nPage==0 );
if( nPage==0 ) sqlite3PagerPagecount(pBt->pPager, &nPage);
@@ -3872,7 +3879,7 @@ static int getOverflowPage(
assert( next==0 || rc==SQLITE_DONE );
if( rc==SQLITE_OK ){
rc = btreeGetPage(pBt, ovfl, &pPage, 0);
rc = btreeGetPage(pBt, ovfl, &pPage, 0, (ppPage==0));
assert( rc==SQLITE_OK || pPage==0 );
if( rc==SQLITE_OK ){
next = get4byte(pPage->aData);
@@ -4093,7 +4100,9 @@ static int accessPayload(
{
DbPage *pDbPage;
rc = sqlite3PagerGet(pBt->pPager, nextPage, &pDbPage);
rc = sqlite3PagerAcquire(pBt->pPager, nextPage, &pDbPage,
(eOp==0 ? PAGER_ACQUIRE_READONLY : 0)
);
if( rc==SQLITE_OK ){
aPayload = sqlite3PagerGetData(pDbPage);
nextPage = get4byte(aPayload);
@@ -4272,10 +4281,11 @@ static int moveToChild(BtCursor *pCur, u32 newPgno){
assert( cursorHoldsMutex(pCur) );
assert( pCur->eState==CURSOR_VALID );
assert( pCur->iPage<BTCURSOR_MAX_DEPTH );
assert( pCur->iPage>=0 );
if( pCur->iPage>=(BTCURSOR_MAX_DEPTH-1) ){
return SQLITE_CORRUPT_BKPT;
}
rc = getAndInitPage(pBt, newPgno, &pNewPage);
rc = getAndInitPage(pBt, newPgno, &pNewPage, (pCur->wrFlag==0));
if( rc ) return rc;
pCur->apPage[i+1] = pNewPage;
pCur->aiIdx[i+1] = 0;
@@ -4392,7 +4402,7 @@ static int moveToRoot(BtCursor *pCur){
pCur->eState = CURSOR_INVALID;
return SQLITE_OK;
}else{
rc = getAndInitPage(pBt, pCur->pgnoRoot, &pCur->apPage[0]);
rc = getAndInitPage(pBt, pCur->pgnoRoot, &pCur->apPage[0], 0);
if( rc!=SQLITE_OK ){
pCur->eState = CURSOR_INVALID;
return rc;
@@ -5006,7 +5016,7 @@ static int allocateBtreePage(
if( iTrunk>mxPage ){
rc = SQLITE_CORRUPT_BKPT;
}else{
rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0, 0);
}
if( rc ){
pTrunk = 0;
@@ -5070,7 +5080,7 @@ static int allocateBtreePage(
goto end_allocate_page;
}
testcase( iNewTrunk==mxPage );
rc = btreeGetPage(pBt, iNewTrunk, &pNewTrunk, 0);
rc = btreeGetPage(pBt, iNewTrunk, &pNewTrunk, 0, 0);
if( rc!=SQLITE_OK ){
goto end_allocate_page;
}
@@ -5150,7 +5160,7 @@ static int allocateBtreePage(
}
put4byte(&aData[4], k-1);
noContent = !btreeGetHasContent(pBt, *pPgno);
rc = btreeGetPage(pBt, *pPgno, ppPage, noContent);
rc = btreeGetPage(pBt, *pPgno, ppPage, noContent, 0);
if( rc==SQLITE_OK ){
rc = sqlite3PagerWrite((*ppPage)->pDbPage);
if( rc!=SQLITE_OK ){
@@ -5198,7 +5208,7 @@ static int allocateBtreePage(
MemPage *pPg = 0;
TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", pBt->nPage));
assert( pBt->nPage!=PENDING_BYTE_PAGE(pBt) );
rc = btreeGetPage(pBt, pBt->nPage, &pPg, bNoContent);
rc = btreeGetPage(pBt, pBt->nPage, &pPg, bNoContent, 0);
if( rc==SQLITE_OK ){
rc = sqlite3PagerWrite(pPg->pDbPage);
releasePage(pPg);
@@ -5212,7 +5222,7 @@ static int allocateBtreePage(
*pPgno = pBt->nPage;
assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
rc = btreeGetPage(pBt, *pPgno, ppPage, bNoContent);
rc = btreeGetPage(pBt, *pPgno, ppPage, bNoContent, 0);
if( rc ) return rc;
rc = sqlite3PagerWrite((*ppPage)->pDbPage);
if( rc!=SQLITE_OK ){
@@ -5280,7 +5290,7 @@ static int freePage2(BtShared *pBt, MemPage *pMemPage, Pgno iPage){
/* If the secure_delete option is enabled, then
** always fully overwrite deleted information with zeros.
*/
if( (!pPage && ((rc = btreeGetPage(pBt, iPage, &pPage, 0))!=0) )
if( (!pPage && ((rc = btreeGetPage(pBt, iPage, &pPage, 0, 0))!=0) )
|| ((rc = sqlite3PagerWrite(pPage->pDbPage))!=0)
){
goto freepage_out;
@@ -5307,7 +5317,7 @@ static int freePage2(BtShared *pBt, MemPage *pMemPage, Pgno iPage){
u32 nLeaf; /* Initial number of leaf cells on trunk page */
iTrunk = get4byte(&pPage1->aData[32]);
rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0, 0);
if( rc!=SQLITE_OK ){
goto freepage_out;
}
@@ -5353,7 +5363,7 @@ static int freePage2(BtShared *pBt, MemPage *pMemPage, Pgno iPage){
** first trunk in the free-list is full. Either way, the page being freed
** will become the new first trunk page in the free-list.
*/
if( pPage==0 && SQLITE_OK!=(rc = btreeGetPage(pBt, iPage, &pPage, 0)) ){
if( pPage==0 && SQLITE_OK!=(rc = btreeGetPage(pBt, iPage, &pPage, 0, 0)) ){
goto freepage_out;
}
rc = sqlite3PagerWrite(pPage->pDbPage);
@@ -6154,7 +6164,7 @@ static int balance_nonroot(
}
pgno = get4byte(pRight);
while( 1 ){
rc = getAndInitPage(pBt, pgno, &apOld[i]);
rc = getAndInitPage(pBt, pgno, &apOld[i], 0);
if( rc ){
memset(apOld, 0, (i+1)*sizeof(MemPage*));
goto balance_cleanup;
@@ -7245,7 +7255,7 @@ static int btreeCreateTable(Btree *p, int *piTable, int createTabFlags){
releasePage(pPageMove);
/* Move the page currently at pgnoRoot to pgnoMove. */
rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0);
rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0, 0);
if( rc!=SQLITE_OK ){
return rc;
}
@@ -7266,7 +7276,7 @@ static int btreeCreateTable(Btree *p, int *piTable, int createTabFlags){
if( rc!=SQLITE_OK ){
return rc;
}
rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0);
rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0, 0);
if( rc!=SQLITE_OK ){
return rc;
}
@@ -7342,7 +7352,7 @@ static int clearDatabasePage(
return SQLITE_CORRUPT_BKPT;
}
rc = getAndInitPage(pBt, pgno, &pPage);
rc = getAndInitPage(pBt, pgno, &pPage, 0);
if( rc ) return rc;
for(i=0; i<pPage->nCell; i++){
pCell = findCell(pPage, i);
@@ -7444,7 +7454,7 @@ static int btreeDropTable(Btree *p, Pgno iTable, int *piMoved){
return SQLITE_LOCKED_SHAREDCACHE;
}
rc = btreeGetPage(pBt, (Pgno)iTable, &pPage, 0);
rc = btreeGetPage(pBt, (Pgno)iTable, &pPage, 0, 0);
if( rc ) return rc;
rc = sqlite3BtreeClearTable(p, iTable, 0);
if( rc ){
@@ -7479,7 +7489,7 @@ static int btreeDropTable(Btree *p, Pgno iTable, int *piMoved){
*/
MemPage *pMove;
releasePage(pPage);
rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0);
rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0, 0);
if( rc!=SQLITE_OK ){
return rc;
}
@@ -7489,7 +7499,7 @@ static int btreeDropTable(Btree *p, Pgno iTable, int *piMoved){
return rc;
}
pMove = 0;
rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0);
rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0, 0);
freePage(pMove, &rc);
releasePage(pMove);
if( rc!=SQLITE_OK ){
@@ -7901,7 +7911,7 @@ static int checkTreePage(
usableSize = pBt->usableSize;
if( iPage==0 ) return 0;
if( checkRef(pCheck, iPage, zParentContext) ) return 0;
if( (rc = btreeGetPage(pBt, (Pgno)iPage, &pPage, 0))!=0 ){
if( (rc = btreeGetPage(pBt, (Pgno)iPage, &pPage, 0, 0))!=0 ){
checkAppendMsg(pCheck, zContext,
"unable to get the page. error code=%d", rc);
return 0;