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Begin adding mutexes. Compiles without SQLITE_OMIT_SHARED_CACHE but we

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get an assertion fault on the shared cache testing. (CVS 4239)

FossilOrigin-Name: 4c1e9ffebe7c611a8b6a89153ae97ab9bca19ea3
This commit is contained in:
drh
2007-08-17 01:14:38 +00:00
parent 6bdec4afb4
commit e53831d644
13 changed files with 449 additions and 219 deletions
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433
src/btree.c
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@@ -9,7 +9,7 @@
** May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.398 2007/08/16 10:09:02 danielk1977 Exp $
** $Id: btree.c,v 1.399 2007/08/17 01:14:38 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
@@ -32,6 +32,36 @@ static const char zMagicHeader[] = SQLITE_FILE_HEADER;
int sqlite3_btree_trace=0; /* True to enable tracing */
#endif
#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** A flag to indicate whether or not shared cache is enabled. Also,
** a list of BtShared objects that are eligible for participation
** in shared cache.
*/
#ifdef SQLITE_TEST
BtShared *sqlite3SharedCacheList = 0;
int sqlite3SharedCacheEnabled = 0;
#else
static BtShared *sqlite3SharedCacheList = 0;
static int sqlite3SharedCacheEnabled = 0;
#endif
#endif /* SQLITE_OMIT_SHARED_CACHE */
#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Enable or disable the shared pager and schema features.
**
** This routine has no effect on existing database connections.
** The shared cache setting effects only future calls to
** sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2().
*/
int sqlite3_enable_shared_cache(int enable){
sqlite3SharedCacheEnabled = enable;
return SQLITE_OK;
}
#endif
/*
** Forward declaration
*/
@@ -50,8 +80,9 @@ static int checkReadLocks(Btree*,Pgno,BtCursor*);
#define queryTableLock(a,b,c) SQLITE_OK
#define lockTable(a,b,c) SQLITE_OK
#define unlockAllTables(a)
#else
#endif
#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Query to see if btree handle p may obtain a lock of type eLock
** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return
@@ -63,7 +94,7 @@ static int queryTableLock(Btree *p, Pgno iTab, u8 eLock){
BtLock *pIter;
/* This is a no-op if the shared-cache is not enabled */
if( 0==sqlite3ThreadDataReadOnly()->useSharedData ){
if( !p->sharable ){
return SQLITE_OK;
}
@@ -96,7 +127,9 @@ static int queryTableLock(Btree *p, Pgno iTab, u8 eLock){
}
return SQLITE_OK;
}
#endif /* !SQLITE_OMIT_SHARED_CACHE */
#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Add a lock on the table with root-page iTable to the shared-btree used
** by Btree handle p. Parameter eLock must be either READ_LOCK or
@@ -111,7 +144,7 @@ static int lockTable(Btree *p, Pgno iTable, u8 eLock){
BtLock *pIter;
/* This is a no-op if the shared-cache is not enabled */
if( 0==sqlite3ThreadDataReadOnly()->useSharedData ){
if( !p->sharable ){
return SQLITE_OK;
}
@@ -164,7 +197,9 @@ static int lockTable(Btree *p, Pgno iTable, u8 eLock){
return SQLITE_OK;
}
#endif /* !SQLITE_OMIT_SHARED_CACHE */
#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Release all the table locks (locks obtained via calls to the lockTable()
** procedure) held by Btree handle p.
@@ -172,11 +207,7 @@ static int lockTable(Btree *p, Pgno iTable, u8 eLock){
static void unlockAllTables(Btree *p){
BtLock **ppIter = &p->pBt->pLock;
/* If the shared-cache extension is not enabled, there should be no
** locks in the BtShared.pLock list, making this procedure a no-op. Assert
** that this is the case.
*/
assert( sqlite3ThreadDataReadOnly()->useSharedData || 0==*ppIter );
assert( p->sharable || 0==*ppIter );
while( *ppIter ){
BtLock *pLock = *ppIter;
@@ -1023,6 +1054,8 @@ static void pageReinit(DbPage *pData, int pageSize){
** zFilename is the name of the database file. If zFilename is NULL
** a new database with a random name is created. This randomly named
** database file will be deleted when sqlite3BtreeClose() is called.
** If zFilename is ":memory:" then an in-memory database is created
** that is automatically destroyed when it is closed.
*/
int sqlite3BtreeOpen(
const char *zFilename, /* Name of the file containing the BTree database */
@@ -1030,14 +1063,11 @@ int sqlite3BtreeOpen(
Btree **ppBtree, /* Pointer to new Btree object written here */
int flags /* Options */
){
BtShared *pBt; /* Shared part of btree structure */
BtShared *pBt = 0; /* Shared part of btree structure */
Btree *p; /* Handle to return */
int rc = SQLITE_OK;
int nReserve;
unsigned char zDbHeader[100];
#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
const ThreadData *pTsdro;
#endif
/* Set the variable isMemdb to true for an in-memory database, or
** false for a file-based database. This symbol is only required if
@@ -1059,106 +1089,150 @@ int sqlite3BtreeOpen(
p->inTrans = TRANS_NONE;
p->pSqlite = pSqlite;
/* Try to find an existing Btree structure opened on zFilename. */
#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
pTsdro = sqlite3ThreadDataReadOnly();
if( pTsdro->useSharedData && zFilename && !isMemdb ){
/*
** If this Btree is a candidate for shared cache, try to find an
** existing BtShared object that we can share with
*/
if( (flags & BTREE_PRIVATE)==0
&& isMemdb==0
&& zFilename && zFilename[0]
&& sqlite3SharedCacheEnabled
){
char *zFullPathname = sqlite3OsFullPathname(zFilename);
sqlite3_mutex *mutexShared;
p->sharable = 1;
if( !zFullPathname ){
sqlite3_free(p);
return SQLITE_NOMEM;
}
for(pBt=pTsdro->pBtree; pBt; pBt=pBt->pNext){
mutexShared = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
sqlite3_mutex_enter(mutexShared);
for(pBt=sqlite3SharedCacheList; pBt; pBt=pBt->pNext){
assert( pBt->nRef>0 );
if( 0==strcmp(zFullPathname, sqlite3PagerFilename(pBt->pPager)) ){
p->pBt = pBt;
*ppBtree = p;
pBt->nRef++;
sqlite3_free(zFullPathname);
return SQLITE_OK;
break;
}
}
sqlite3_mutex_leave(mutexShared);
sqlite3_free(zFullPathname);
}
#endif
/*
** The following asserts make sure that structures used by the btree are
** the right size. This is to guard against size changes that result
** when compiling on a different architecture.
*/
assert( sizeof(i64)==8 || sizeof(i64)==4 );
assert( sizeof(u64)==8 || sizeof(u64)==4 );
assert( sizeof(u32)==4 );
assert( sizeof(u16)==2 );
assert( sizeof(Pgno)==4 );
pBt = sqlite3MallocZero( sizeof(*pBt) );
if( pBt==0 ){
rc = SQLITE_NOMEM;
goto btree_open_out;
}
rc = sqlite3PagerOpen(&pBt->pPager, zFilename, EXTRA_SIZE, flags);
if( rc==SQLITE_OK ){
rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
}
if( rc!=SQLITE_OK ){
goto btree_open_out;
}
p->pBt = pBt;
sqlite3PagerSetDestructor(pBt->pPager, pageDestructor);
sqlite3PagerSetReiniter(pBt->pPager, pageReinit);
pBt->pCursor = 0;
pBt->pPage1 = 0;
pBt->readOnly = sqlite3PagerIsreadonly(pBt->pPager);
pBt->pageSize = get2byte(&zDbHeader[16]);
if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE
|| ((pBt->pageSize-1)&pBt->pageSize)!=0 ){
pBt->pageSize = SQLITE_DEFAULT_PAGE_SIZE;
pBt->maxEmbedFrac = 64; /* 25% */
pBt->minEmbedFrac = 32; /* 12.5% */
pBt->minLeafFrac = 32; /* 12.5% */
#ifndef SQLITE_OMIT_AUTOVACUUM
/* If the magic name ":memory:" will create an in-memory database, then
** leave the autoVacuum mode at 0 (do not auto-vacuum), even if
** SQLITE_DEFAULT_AUTOVACUUM is true. On the other hand, if
** SQLITE_OMIT_MEMORYDB has been defined, then ":memory:" is just a
** regular file-name. In this case the auto-vacuum applies as per normal.
/*
** The following asserts make sure that structures used by the btree are
** the right size. This is to guard against size changes that result
** when compiling on a different architecture.
*/
if( zFilename && !isMemdb ){
pBt->autoVacuum = (SQLITE_DEFAULT_AUTOVACUUM ? 1 : 0);
pBt->incrVacuum = (SQLITE_DEFAULT_AUTOVACUUM==2 ? 1 : 0);
assert( sizeof(i64)==8 || sizeof(i64)==4 );
assert( sizeof(u64)==8 || sizeof(u64)==4 );
assert( sizeof(u32)==4 );
assert( sizeof(u16)==2 );
assert( sizeof(Pgno)==4 );
pBt = sqlite3MallocZero( sizeof(*pBt) );
if( pBt==0 ){
rc = SQLITE_NOMEM;
goto btree_open_out;
}
rc = sqlite3PagerOpen(&pBt->pPager, zFilename, EXTRA_SIZE, flags);
if( rc==SQLITE_OK ){
rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
}
if( rc!=SQLITE_OK ){
goto btree_open_out;
}
p->pBt = pBt;
sqlite3PagerSetDestructor(pBt->pPager, pageDestructor);
sqlite3PagerSetReiniter(pBt->pPager, pageReinit);
pBt->pCursor = 0;
pBt->pPage1 = 0;
pBt->readOnly = sqlite3PagerIsreadonly(pBt->pPager);
pBt->pageSize = get2byte(&zDbHeader[16]);
if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE
|| ((pBt->pageSize-1)&pBt->pageSize)!=0 ){
pBt->pageSize = SQLITE_DEFAULT_PAGE_SIZE;
pBt->maxEmbedFrac = 64; /* 25% */
pBt->minEmbedFrac = 32; /* 12.5% */
pBt->minLeafFrac = 32; /* 12.5% */
#ifndef SQLITE_OMIT_AUTOVACUUM
/* If the magic name ":memory:" will create an in-memory database, then
** leave the autoVacuum mode at 0 (do not auto-vacuum), even if
** SQLITE_DEFAULT_AUTOVACUUM is true. On the other hand, if
** SQLITE_OMIT_MEMORYDB has been defined, then ":memory:" is just a
** regular file-name. In this case the auto-vacuum applies as per normal.
*/
if( zFilename && !isMemdb ){
pBt->autoVacuum = (SQLITE_DEFAULT_AUTOVACUUM ? 1 : 0);
pBt->incrVacuum = (SQLITE_DEFAULT_AUTOVACUUM==2 ? 1 : 0);
}
#endif
nReserve = 0;
}else{
nReserve = zDbHeader[20];
pBt->maxEmbedFrac = zDbHeader[21];
pBt->minEmbedFrac = zDbHeader[22];
pBt->minLeafFrac = zDbHeader[23];
pBt->pageSizeFixed = 1;
#ifndef SQLITE_OMIT_AUTOVACUUM
pBt->autoVacuum = (get4byte(&zDbHeader[36 + 4*4])?1:0);
pBt->incrVacuum = (get4byte(&zDbHeader[36 + 7*4])?1:0);
#endif
}
pBt->usableSize = pBt->pageSize - nReserve;
assert( (pBt->pageSize & 7)==0 ); /* 8-byte alignment of pageSize */
sqlite3PagerSetPagesize(pBt->pPager, pBt->pageSize);
#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
/* Add the new BtShared object to the linked list sharable BtShareds.
*/
if( p->sharable ){
sqlite3_mutex *mutexShared;
pBt->nRef = 1;
mutexShared = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
pBt->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
sqlite3_mutex_enter(mutexShared);
pBt->pNext = sqlite3SharedCacheList;
sqlite3SharedCacheList = pBt;
sqlite3_mutex_leave(mutexShared);
}
#endif
nReserve = 0;
}else{
nReserve = zDbHeader[20];
pBt->maxEmbedFrac = zDbHeader[21];
pBt->minEmbedFrac = zDbHeader[22];
pBt->minLeafFrac = zDbHeader[23];
pBt->pageSizeFixed = 1;
#ifndef SQLITE_OMIT_AUTOVACUUM
pBt->autoVacuum = (get4byte(&zDbHeader[36 + 4*4])?1:0);
pBt->incrVacuum = (get4byte(&zDbHeader[36 + 7*4])?1:0);
#endif
}
pBt->usableSize = pBt->pageSize - nReserve;
assert( (pBt->pageSize & 7)==0 ); /* 8-byte alignment of pageSize */
sqlite3PagerSetPagesize(pBt->pPager, pBt->pageSize);
#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
/* Add the new btree to the linked list starting at ThreadData.pBtree.
** There is no chance that a malloc() may fail inside of the
** sqlite3ThreadData() call, as the ThreadData structure must have already
** been allocated for pTsdro->useSharedData to be non-zero.
/* If the new Btree uses a sharable pBtShared, then link the new
** Btree into the list of all sharable Btrees for the same connection.
** The list is kept in ascending order by pBtShared address.
*/
if( pTsdro->useSharedData && zFilename && !isMemdb ){
pBt->pNext = pTsdro->pBtree;
sqlite3ThreadData()->pBtree = pBt;
if( p->sharable ){
int i;
Btree *pSib;
for(i=0; i<pSqlite->nDb; i++){
if( (pSib = pSqlite->aDb[i].pBt)!=0 && pSib->sharable ){
while( pSib->pPrev ){ pSib = pSib->pPrev; }
if( p->pBt<pSib->pBt ){
p->pNext = pSib;
p->pPrev = 0;
pSib->pPrev = p;
}else{
while( pSib->pNext && pSib->pNext->pBt>p->pBt ){
pSib = pSib->pNext;
}
p->pNext = pSib->pNext;
p->pPrev = pSib;
if( p->pNext ){
p->pNext->pPrev = p;
}
pSib->pNext = p;
}
break;
}
}
}
#endif
pBt->nRef = 1;
*ppBtree = p;
btree_open_out:
@@ -1173,6 +1247,43 @@ btree_open_out:
return rc;
}
/*
** Decrement the BtShared.nRef counter. When it reaches zero,
** remove the BtShared structure from the sharing list. Return
** true if the BtShared.nRef counter reaches zero and return
** false if it is still positive.
*/
static int removeFromSharingList(BtShared *pBt){
#ifndef SQLITE_OMIT_SHARED_CACHE
sqlite3_mutex *pMaster;
BtShared *pList;
int removed = 0;
pMaster = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
sqlite3_mutex_enter(pMaster);
pBt->nRef--;
if( pBt->nRef<=0 ){
if( sqlite3SharedCacheList==pBt ){
sqlite3SharedCacheList = pBt->pNext;
}else{
pList = sqlite3SharedCacheList;
while( pList && pList->pNext!=pBt ){
pList=pList->pNext;
}
if( pList ){
pList->pNext = pBt->pNext;
}
}
sqlite3_mutex_free(pBt->mutex);
removed = 1;
}
sqlite3_mutex_leave(pMaster);
return removed;
#else
return 1;
#endif
}
/*
** Close an open database and invalidate all cursors.
*/
@@ -1180,11 +1291,8 @@ int sqlite3BtreeClose(Btree *p){
BtShared *pBt = p->pBt;
BtCursor *pCur;
#ifndef SQLITE_OMIT_SHARED_CACHE
ThreadData *pTsd;
#endif
/* Close all cursors opened via this handle. */
sqlite3BtreeEnter(p);
pCur = pBt->pCursor;
while( pCur ){
BtCursor *pTmp = pCur;
@@ -1199,48 +1307,131 @@ int sqlite3BtreeClose(Btree *p){
** this handle.
*/
sqlite3BtreeRollback(p);
sqlite3_free(p);
sqlite3BtreeLeave(p);
#ifndef SQLITE_OMIT_SHARED_CACHE
/* If there are still other outstanding references to the shared-btree
** structure, return now. The remainder of this procedure cleans
** up the shared-btree.
*/
assert( pBt->nRef>0 );
pBt->nRef--;
if( pBt->nRef ){
return SQLITE_OK;
assert( p->wantToLock==0 && p->locked==0 );
if( !p->sharable || removeFromSharingList(pBt) ){
/* The pBt is no longer on the sharing list, so we can access
** it without having to hold the mutex.
**
** Clean out and delete the BtShared object.
*/
assert( !pBt->pCursor );
assert( pBt->nRef==0 );
sqlite3PagerClose(pBt->pPager);
if( pBt->xFreeSchema && pBt->pSchema ){
pBt->xFreeSchema(pBt->pSchema);
}
sqlite3_free(pBt->pSchema);
sqlite3_free(pBt);
}
/* Remove the shared-btree from the thread wide list. Call
** ThreadDataReadOnly() and then cast away the const property of the
** pointer to avoid allocating thread data if it is not really required.
*/
pTsd = (ThreadData *)sqlite3ThreadDataReadOnly();
if( pTsd->pBtree==pBt ){
assert( pTsd==sqlite3ThreadData() );
pTsd->pBtree = pBt->pNext;
}else{
BtShared *pPrev;
for(pPrev=pTsd->pBtree; pPrev && pPrev->pNext!=pBt; pPrev=pPrev->pNext){}
if( pPrev ){
assert( pTsd==sqlite3ThreadData() );
pPrev->pNext = pBt->pNext;
}
#ifndef SQLITE_OMIT_SHARED_CACHE
else{
assert( p->wantToLock==0 );
assert( p->locked==0 );
assert( p->sharable );
if( p->pPrev ) p->pPrev->pNext = p->pNext;
if( p->pNext ) p->pNext->pPrev = p->pPrev;
}
#endif
/* Close the pager and free the shared-btree structure */
assert( !pBt->pCursor );
sqlite3PagerClose(pBt->pPager);
if( pBt->xFreeSchema && pBt->pSchema ){
pBt->xFreeSchema(pBt->pSchema);
}
sqlite3_free(pBt->pSchema);
sqlite3_free(pBt);
sqlite3_free(p);
return SQLITE_OK;
}
#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Enter a mutex on the given BTree object.
**
** If the object is not sharable, then no mutex is ever required
** and this routine is a no-op. The underlying mutex is non-recursive.
** But we keep a reference count in Btree.wantToLock so the behavior
** of this interface is recursive.
**
** To avoid deadlocks, multiple Btrees are locked in the same order
** by all database connections. The p->pNext is a list of other
** Btrees belonging to the same database connection as the p Btree
** which need to be locked after p. If we cannot get a lock on
** p, then first unlock all of the others on p->pNext, then wait
** for the lock to become available on p, then relock all of the
** subsequent Btrees that desire a lock.
*/
void sqlite3BtreeEnter(Btree *p){
Btree *pLater;
/* Some basic sanity checking on the Btree. The list of Btrees
** connected by pNext and pPrev should be in sorted order by
** Btree.pBt value. All elements of the list should belong to
** the same connection. Only shared Btrees are on the list. */
assert( p->pNext==0 || p->pNext->pBt>p->pBt );
assert( p->pPrev==0 || p->pPrev->pBt<p->pBt );
assert( p->pNext==0 || p->pNext->pSqlite==p->pSqlite );
assert( p->pPrev==0 || p->pPrev->pSqlite==p->pSqlite );
assert( p->sharable || (p->pNext==0 && p->pPrev==0) );
/* Check for locking consistency */
assert( !p->locked || p->wantToLock>0 );
assert( p->sharable || p->wantToLock==0 );
if( !p->sharable ) return;
p->wantToLock++;
if( p->locked ) return;
/* In most cases, we should be able to acquire the lock we
** want without having to go throught the ascending lock
** procedure that follows. Just be sure not to block.
*/
if( sqlite3_mutex_try(p->pBt->mutex)==SQLITE_OK ){
p->locked = 1;
return;
}
/* To avoid deadlock, first release all locks with a larger
** BtShared address. Then acquire our lock. Then reacquire
** the other BtShared locks that we used to hold in ascending
** order.
*/
for(pLater=p->pNext; pLater; pLater=pLater->pNext){
assert( pLater->sharable );
assert( pLater->pNext==0 || pLater->pNext->pBt>pLater->pBt );
assert( !pLater->locked || pLater->wantToLock>0 );
if( pLater->locked ){
sqlite3_mutex_leave(pLater->pBt->mutex);
pLater->locked = 0;
}
}
sqlite3_mutex_enter(p->pBt->mutex);
for(pLater=p->pNext; pLater; pLater=pLater->pNext){
if( pLater->wantToLock ){
sqlite3_mutex_enter(pLater->pBt->mutex);
pLater->locked = 1;
}
}
}
#endif /* !SQLITE_OMIT_SHARED_CACHE */
/*
** Exit the recursive mutex on a Btree.
*/
#ifndef SQLITE_OMIT_SHARED_CACHE
void sqlite3BtreeLeave(Btree *p){
if( p->sharable ){
assert( p->wantToLock>0 );
p->wantToLock--;
if( p->wantToLock==0 ){
assert( p->locked );
sqlite3_mutex_leave(p->pBt->mutex);
p->locked = 0;
}
}
}
#endif /* !SQLITE_OMIT_SHARED_CACHE */
/*
** Change the busy handler callback function.
*/