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-rw-r--r--src/btree.c290
-rw-r--r--src/test3.c7
-rw-r--r--src/vdbe.c4
-rw-r--r--src/vdbeblob.c50
4 files changed, 214 insertions, 137 deletions
diff --git a/src/btree.c b/src/btree.c
index 6c770cd0f..68f196206 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -9,7 +9,7 @@
** May you share freely, never taking more than you give.
**
*************************************************************************
-** $Id: btree.c,v 1.645 2009/06/26 16:32:13 shane Exp $
+** $Id: btree.c,v 1.646 2009/06/29 06:00:37 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
@@ -67,11 +67,6 @@ int sqlite3_enable_shared_cache(int enable){
#endif
-/*
-** Forward declaration
-*/
-static int checkForReadConflicts(Btree*, Pgno, BtCursor*, i64);
-
#ifdef SQLITE_OMIT_SHARED_CACHE
/*
@@ -86,9 +81,113 @@ static int checkForReadConflicts(Btree*, Pgno, BtCursor*, i64);
#define querySharedCacheTableLock(a,b,c) SQLITE_OK
#define setSharedCacheTableLock(a,b,c) SQLITE_OK
#define clearAllSharedCacheTableLocks(a)
+ #define hasSharedCacheTableLock(a,b,c,d) 1
+ #define hasReadConflicts(a, b) 0
#endif
#ifndef SQLITE_OMIT_SHARED_CACHE
+
+#ifdef SQLITE_DEBUG
+/*
+** This function is only used as part of an assert() statement. It checks
+** that connection p holds the required locks to read or write to the
+** b-tree with root page iRoot. If so, true is returned. Otherwise, false.
+** For example, when writing to a table b-tree with root-page iRoot via
+** Btree connection pBtree:
+**
+** assert( hasSharedCacheTableLock(pBtree, iRoot, 0, WRITE_LOCK) );
+**
+** When writing to an index b-tree that resides in a sharable database, the
+** caller should have first obtained a lock specifying the root page of
+** the corresponding table b-tree. This makes things a bit more complicated,
+** as this module treats each b-tree as a separate structure. To determine
+** the table b-tree corresponding to the index b-tree being written, this
+** function has to search through the database schema.
+**
+** Instead of a lock on the b-tree rooted at page iRoot, the caller may
+** hold a write-lock on the schema table (root page 1). This is also
+** acceptable.
+*/
+static int hasSharedCacheTableLock(
+ Btree *pBtree, /* Handle that must hold lock */
+ Pgno iRoot, /* Root page of b-tree */
+ int isIndex, /* True if iRoot is the root of an index b-tree */
+ int eLockType /* Required lock type (READ_LOCK or WRITE_LOCK) */
+){
+ Schema *pSchema = (Schema *)pBtree->pBt->pSchema;
+ Pgno iTab = 0;
+ BtLock *pLock;
+
+ /* If this b-tree database is not shareable, or if the client is reading
+ ** and has the read-uncommitted flag set, then no lock is required.
+ ** In these cases return true immediately. If the client is reading
+ ** or writing an index b-tree, but the schema is not loaded, then return
+ ** true also. In this case the lock is required, but it is too difficult
+ ** to check if the client actually holds it. This doesn't happen very
+ ** often. */
+ if( (pBtree->sharable==0)
+ || (eLockType==READ_LOCK && (pBtree->db->flags & SQLITE_ReadUncommitted))
+ || (isIndex && (!pSchema || (pSchema->flags&DB_SchemaLoaded)==0 ))
+ ){
+ return 1;
+ }
+
+ /* Figure out the root-page that the lock should be held on. For table
+ ** b-trees, this is just the root page of the b-tree being read or
+ ** written. For index b-trees, it is the root page of the associated
+ ** table. */
+ if( isIndex ){
+ HashElem *p;
+ for(p=sqliteHashFirst(&pSchema->idxHash); p; p=sqliteHashNext(p)){
+ Index *pIdx = (Index *)sqliteHashData(p);
+ if( pIdx->tnum==iRoot ){
+ iTab = pIdx->pTable->tnum;
+ }
+ }
+ }else{
+ iTab = iRoot;
+ }
+
+ /* Search for the required lock. Either a write-lock on root-page iTab, a
+ ** write-lock on the schema table, or (if the client is reading) a
+ ** read-lock on iTab will suffice. Return 1 if any of these are found. */
+ for(pLock=pBtree->pBt->pLock; pLock; pLock=pLock->pNext){
+ if( pLock->pBtree==pBtree
+ && (pLock->iTable==iTab || (pLock->eLock==WRITE_LOCK && pLock->iTable==1))
+ && pLock->eLock>=eLockType
+ ){
+ return 1;
+ }
+ }
+
+ /* Failed to find the required lock. */
+ return 0;
+}
+
+/*
+** This function is also used as part of assert() statements only. It
+** returns true if there exist one or more cursors open on the table
+** with root page iRoot that do not belong to either connection pBtree
+** or some other connection that has the read-uncommitted flag set.
+**
+** For example, before writing to page iRoot:
+**
+** assert( !hasReadConflicts(pBtree, iRoot) );
+*/
+static int hasReadConflicts(Btree *pBtree, Pgno iRoot){
+ BtCursor *p;
+ for(p=pBtree->pBt->pCursor; p; p=p->pNext){
+ if( p->pgnoRoot==iRoot
+ && p->pBtree!=pBtree
+ && 0==(p->pBtree->db->flags & SQLITE_ReadUncommitted)
+ ){
+ return 1;
+ }
+ }
+ return 0;
+}
+#endif /* #ifdef SQLITE_DEBUG */
+
/*
** 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
@@ -326,9 +425,41 @@ static void invalidateAllOverflowCache(BtShared *pBt){
invalidateOverflowCache(p);
}
}
+
+/*
+** This function is called before modifying the contents of a table
+** b-tree to invalidate any incrblob cursors that are open on the
+** row or one of the rows being modified. Argument pgnoRoot is the
+** root-page of the table b-tree.
+**
+** If argument isClearTable is true, then the entire contents of the
+** table is about to be deleted. In this case invalidate all incrblob
+** cursors open on any row within the table with root-page pgnoRoot.
+**
+** Otherwise, if argument isClearTable is false, then the row with
+** rowid iRow is being replaced or deleted. In this case invalidate
+** only those incrblob cursors open on this specific row.
+*/
+static void invalidateIncrblobCursors(
+ Btree *pBtree, /* The database file to check */
+ Pgno pgnoRoot, /* Look for read cursors on this btree */
+ i64 iRow, /* The rowid that might be changing */
+ int isClearTable /* True if all rows are being deleted */
+){
+ BtCursor *p;
+ BtShared *pBt = pBtree->pBt;
+ assert( sqlite3BtreeHoldsMutex(pBtree) );
+ for(p=pBt->pCursor; p; p=p->pNext){
+ if( p->isIncrblobHandle && (isClearTable || p->info.nKey==iRow) ){
+ p->eState = CURSOR_INVALID;
+ }
+ }
+}
+
#else
#define invalidateOverflowCache(x)
#define invalidateAllOverflowCache(x)
+ #define invalidateIncrblobCursors(w,x,y,z)
#endif
/*
@@ -3055,16 +3186,22 @@ static int btreeCursor(
assert( sqlite3BtreeHoldsMutex(p) );
assert( wrFlag==0 || wrFlag==1 );
- if( wrFlag ){
- assert( !pBt->readOnly );
- if( NEVER(pBt->readOnly) ){
- return SQLITE_READONLY;
- }
- rc = checkForReadConflicts(p, iTable, 0, 0);
- if( rc!=SQLITE_OK ){
- assert( rc==SQLITE_LOCKED_SHAREDCACHE );
- return rc;
- }
+
+ /* The following assert statements verify that if this is a sharable b-tree
+ ** database, the connection is holding the required table locks, and that
+ ** no other connection has any open cursor that conflicts with this lock.
+ **
+ ** The exception to this is read-only cursors open on the schema table.
+ ** Such a cursor is opened without a lock while reading the database
+ ** schema. This is safe because BtShared.mutex is held for the entire
+ ** lifetime of this cursor. */
+ assert( (iTable==1 && wrFlag==0)
+ || hasSharedCacheTableLock(p, iTable, pKeyInfo!=0, wrFlag+1)
+ );
+ assert( wrFlag==0 || !hasReadConflicts(p, iTable) );
+
+ if( NEVER(wrFlag && pBt->readOnly) ){
+ return SQLITE_READONLY;
}
if( pBt->pPage1==0 ){
@@ -6210,75 +6347,6 @@ static int balance(BtCursor *pCur){
return rc;
}
-/*
-** This routine checks all cursors that point to table pgnoRoot.
-** If any of those cursors were opened with wrFlag==0 in a different
-** database connection (a database connection that shares the pager
-** cache with the current connection) and that other connection
-** is not in the ReadUncommmitted state, then this routine returns
-** SQLITE_LOCKED.
-**
-** As well as cursors with wrFlag==0, cursors with
-** isIncrblobHandle==1 are also considered 'read' cursors because
-** incremental blob cursors are used for both reading and writing.
-**
-** When pgnoRoot is the root page of an intkey table, this function is also
-** responsible for invalidating incremental blob cursors when the table row
-** on which they are opened is deleted or modified. Cursors are invalidated
-** according to the following rules:
-**
-** 1) When BtreeClearTable() is called to completely delete the contents
-** of a B-Tree table, pExclude is set to zero and parameter iRow is
-** set to non-zero. In this case all incremental blob cursors open
-** on the table rooted at pgnoRoot are invalidated.
-**
-** 2) When BtreeInsert(), BtreeDelete() or BtreePutData() is called to
-** modify a table row via an SQL statement, pExclude is set to the
-** write cursor used to do the modification and parameter iRow is set
-** to the integer row id of the B-Tree entry being modified. Unless
-** pExclude is itself an incremental blob cursor, then all incremental
-** blob cursors open on row iRow of the B-Tree are invalidated.
-**
-** 3) If both pExclude and iRow are set to zero, no incremental blob
-** cursors are invalidated.
-*/
-static int checkForReadConflicts(
- Btree *pBtree, /* The database file to check */
- Pgno pgnoRoot, /* Look for read cursors on this btree */
- BtCursor *pExclude, /* Ignore this cursor */
- i64 iRow /* The rowid that might be changing */
-){
- BtCursor *p;
- BtShared *pBt = pBtree->pBt;
- sqlite3 *db = pBtree->db;
- assert( sqlite3BtreeHoldsMutex(pBtree) );
- for(p=pBt->pCursor; p; p=p->pNext){
- if( p==pExclude ) continue;
- if( p->pgnoRoot!=pgnoRoot ) continue;
-#ifndef SQLITE_OMIT_INCRBLOB
- if( p->isIncrblobHandle && (
- (!pExclude && iRow)
- || (pExclude && !pExclude->isIncrblobHandle && p->info.nKey==iRow)
- )){
- p->eState = CURSOR_INVALID;
- }
-#endif
- if( p->eState!=CURSOR_VALID ) continue;
- if( p->wrFlag==0
-#ifndef SQLITE_OMIT_INCRBLOB
- || p->isIncrblobHandle
-#endif
- ){
- sqlite3 *dbOther = p->pBtree->db;
- assert(dbOther);
- if( dbOther!=db && (dbOther->flags & SQLITE_ReadUncommitted)==0 ){
- sqlite3ConnectionBlocked(db, dbOther);
- return SQLITE_LOCKED_SHAREDCACHE;
- }
- }
- }
- return SQLITE_OK;
-}
/*
** Insert a new record into the BTree. The key is given by (pKey,nKey)
@@ -6322,12 +6390,15 @@ int sqlite3BtreeInsert(
assert( pBt->inTransaction==TRANS_WRITE );
assert( !pBt->readOnly );
assert( pCur->wrFlag );
- rc = checkForReadConflicts(pCur->pBtree, pCur->pgnoRoot, pCur, nKey);
- if( rc ){
- /* The table pCur points to has a read lock */
- assert( rc==SQLITE_LOCKED_SHAREDCACHE );
- return rc;
+ assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) );
+
+ /* If this is an insert into a table b-tree, invalidate any incrblob
+ ** cursors open on the row being replaced (assuming this is a replace
+ ** operation - if it is not, the following is a no-op). */
+ if( pCur->pKeyInfo==0 ){
+ invalidateIncrblobCursors(p, pCur->pgnoRoot, nKey, 0);
}
+
if( pCur->eState==CURSOR_FAULT ){
return pCur->skip;
}
@@ -6448,16 +6519,19 @@ int sqlite3BtreeDelete(BtCursor *pCur){
assert( pBt->inTransaction==TRANS_WRITE );
assert( !pBt->readOnly );
assert( pCur->wrFlag );
+ assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) );
+ assert( !hasReadConflicts(p, pCur->pgnoRoot) );
+
if( NEVER(pCur->aiIdx[pCur->iPage]>=pCur->apPage[pCur->iPage]->nCell)
|| NEVER(pCur->eState!=CURSOR_VALID)
){
return SQLITE_ERROR; /* Something has gone awry. */
}
- rc = checkForReadConflicts(p, pCur->pgnoRoot, pCur, pCur->info.nKey);
- if( rc!=SQLITE_OK ){
- assert( rc==SQLITE_LOCKED_SHAREDCACHE );
- return rc; /* The table pCur points to has a read lock */
+ /* If this is a delete operation to remove a row from a table b-tree,
+ ** invalidate any incrblob cursors open on the row being deleted. */
+ if( pCur->pKeyInfo==0 ){
+ invalidateIncrblobCursors(p, pCur->pgnoRoot, pCur->info.nKey, 0);
}
iCellDepth = pCur->iPage;
@@ -6757,11 +6831,13 @@ int sqlite3BtreeClearTable(Btree *p, int iTable, int *pnChange){
BtShared *pBt = p->pBt;
sqlite3BtreeEnter(p);
assert( p->inTrans==TRANS_WRITE );
- if( (rc = checkForReadConflicts(p, iTable, 0, 1))!=SQLITE_OK ){
- /* nothing to do */
- }else if( SQLITE_OK!=(rc = saveAllCursors(pBt, iTable, 0)) ){
- /* nothing to do */
- }else{
+
+ /* Invalidate all incrblob cursors open on table iTable (assuming iTable
+ ** is the root of a table b-tree - if it is not, the following call is
+ ** a no-op). */
+ invalidateIncrblobCursors(p, iTable, 0, 1);
+
+ if( SQLITE_OK==(rc = saveAllCursors(pBt, (Pgno)iTable, 0)) ){
rc = clearDatabasePage(pBt, (Pgno)iTable, 0, pnChange);
}
sqlite3BtreeLeave(p);
@@ -7687,11 +7763,9 @@ int sqlite3BtreeLockTable(Btree *p, int iTab, u8 isWriteLock){
** to change the length of the data stored.
*/
int sqlite3BtreePutData(BtCursor *pCsr, u32 offset, u32 amt, void *z){
- int rc;
-
assert( cursorHoldsMutex(pCsr) );
assert( sqlite3_mutex_held(pCsr->pBtree->db->mutex) );
- assert(pCsr->isIncrblobHandle);
+ assert( pCsr->isIncrblobHandle );
restoreCursorPosition(pCsr);
assert( pCsr->eState!=CURSOR_REQUIRESEEK );
@@ -7707,14 +7781,10 @@ int sqlite3BtreePutData(BtCursor *pCsr, u32 offset, u32 amt, void *z){
if( !pCsr->wrFlag ){
return SQLITE_READONLY;
}
- assert( !pCsr->pBt->readOnly
- && pCsr->pBt->inTransaction==TRANS_WRITE );
- rc = checkForReadConflicts(pCsr->pBtree, pCsr->pgnoRoot, pCsr, 0);
- if( rc!=SQLITE_OK ){
- /* The table pCur points to has a read lock */
- assert( rc==SQLITE_LOCKED_SHAREDCACHE );
- return rc;
- }
+ assert( !pCsr->pBt->readOnly && pCsr->pBt->inTransaction==TRANS_WRITE );
+ assert( hasSharedCacheTableLock(pCsr->pBtree, pCsr->pgnoRoot, 0, 2) );
+ assert( !hasReadConflicts(pCsr->pBtree, pCsr->pgnoRoot) );
+
if( pCsr->eState==CURSOR_INVALID || !pCsr->apPage[pCsr->iPage]->intKey ){
return SQLITE_ERROR;
}
diff --git a/src/test3.c b/src/test3.c
index 3a795b704..f60596270 100644
--- a/src/test3.c
+++ b/src/test3.c
@@ -13,7 +13,7 @@
** is not included in the SQLite library. It is used for automated
** testing of the SQLite library.
**
-** $Id: test3.c,v 1.104 2009/05/04 11:42:30 danielk1977 Exp $
+** $Id: test3.c,v 1.105 2009/06/29 06:00:37 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "btreeInt.h"
@@ -626,7 +626,10 @@ static int btree_cursor(
pCur = (BtCursor *)ckalloc(sqlite3BtreeCursorSize());
memset(pCur, 0, sqlite3BtreeCursorSize());
sqlite3BtreeEnter(pBt);
- rc = sqlite3BtreeCursor(pBt, iTable, wrFlag, 0, pCur);
+ rc = sqlite3BtreeLockTable(pBt, iTable, wrFlag);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3BtreeCursor(pBt, iTable, wrFlag, 0, pCur);
+ }
sqlite3BtreeLeave(pBt);
if( rc ){
ckfree((char *)pCur);
diff --git a/src/vdbe.c b/src/vdbe.c
index c865a7f57..c5b87da4b 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -43,7 +43,7 @@
** in this file for details. If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
-** $Id: vdbe.c,v 1.866 2009/06/26 16:32:13 shane Exp $
+** $Id: vdbe.c,v 1.867 2009/06/29 06:00:37 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"
@@ -4994,7 +4994,7 @@ case OP_Expire: {
** Obtain a lock on a particular table. This instruction is only used when
** the shared-cache feature is enabled.
**
-** If P1 is the index of the database in sqlite3.aDb[] of the database
+** P1 is the index of the database in sqlite3.aDb[] of the database
** on which the lock is acquired. A readlock is obtained if P3==0 or
** a write lock if P3==1.
**
diff --git a/src/vdbeblob.c b/src/vdbeblob.c
index d60a0d98c..b08cec344 100644
--- a/src/vdbeblob.c
+++ b/src/vdbeblob.c
@@ -12,7 +12,7 @@
**
** This file contains code used to implement incremental BLOB I/O.
**
-** $Id: vdbeblob.c,v 1.33 2009/06/01 19:53:31 drh Exp $
+** $Id: vdbeblob.c,v 1.34 2009/06/29 06:00:37 danielk1977 Exp $
*/
#include "sqliteInt.h"
@@ -66,19 +66,18 @@ int sqlite3_blob_open(
static const VdbeOpList openBlob[] = {
{OP_Transaction, 0, 0, 0}, /* 0: Start a transaction */
{OP_VerifyCookie, 0, 0, 0}, /* 1: Check the schema cookie */
-
- /* One of the following two instructions is replaced by an
- ** OP_Noop before exection.
- */
- {OP_OpenRead, 0, 0, 0}, /* 2: Open cursor 0 for reading */
- {OP_OpenWrite, 0, 0, 0}, /* 3: Open cursor 0 for read/write */
-
- {OP_Variable, 1, 1, 1}, /* 4: Push the rowid to the stack */
- {OP_NotExists, 0, 8, 1}, /* 5: Seek the cursor */
- {OP_Column, 0, 0, 1}, /* 6 */
- {OP_ResultRow, 1, 0, 0}, /* 7 */
- {OP_Close, 0, 0, 0}, /* 8 */
- {OP_Halt, 0, 0, 0}, /* 9 */
+ {OP_TableLock, 0, 0, 0}, /* 2: Acquire a read or write lock */
+
+ /* One of the following two instructions is replaced by an OP_Noop. */
+ {OP_OpenRead, 0, 0, 0}, /* 3: Open cursor 0 for reading */
+ {OP_OpenWrite, 0, 0, 0}, /* 4: Open cursor 0 for read/write */
+
+ {OP_Variable, 1, 1, 1}, /* 5: Push the rowid to the stack */
+ {OP_NotExists, 0, 9, 1}, /* 6: Seek the cursor */
+ {OP_Column, 0, 0, 1}, /* 7 */
+ {OP_ResultRow, 1, 0, 0}, /* 8 */
+ {OP_Close, 0, 0, 0}, /* 9 */
+ {OP_Halt, 0, 0, 0}, /* 10 */
};
Vdbe *v = 0;
@@ -170,10 +169,11 @@ int sqlite3_blob_open(
if( v ){
int iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
sqlite3VdbeAddOpList(v, sizeof(openBlob)/sizeof(VdbeOpList), openBlob);
+ flags = !!flags; /* flags = (flags ? 1 : 0); */
/* Configure the OP_Transaction */
sqlite3VdbeChangeP1(v, 0, iDb);
- sqlite3VdbeChangeP2(v, 0, (flags ? 1 : 0));
+ sqlite3VdbeChangeP2(v, 0, flags);
/* Configure the OP_VerifyCookie */
sqlite3VdbeChangeP1(v, 1, iDb);
@@ -182,13 +182,17 @@ int sqlite3_blob_open(
/* Make sure a mutex is held on the table to be accessed */
sqlite3VdbeUsesBtree(v, iDb);
+ /* Configure the OP_TableLock instruction */
+ sqlite3VdbeChangeP1(v, 2, iDb);
+ sqlite3VdbeChangeP2(v, 2, pTab->tnum);
+ sqlite3VdbeChangeP3(v, 2, flags);
+ sqlite3VdbeChangeP4(v, 2, pTab->zName, P4_TRANSIENT);
+
/* Remove either the OP_OpenWrite or OpenRead. Set the P2
- ** parameter of the other to pTab->tnum.
- */
- flags = !!flags;
- sqlite3VdbeChangeToNoop(v, 3 - flags, 1);
- sqlite3VdbeChangeP2(v, 2 + flags, pTab->tnum);
- sqlite3VdbeChangeP3(v, 2 + flags, iDb);
+ ** parameter of the other to pTab->tnum. */
+ sqlite3VdbeChangeToNoop(v, 4 - flags, 1);
+ sqlite3VdbeChangeP2(v, 3 + flags, pTab->tnum);
+ sqlite3VdbeChangeP3(v, 3 + flags, iDb);
/* Configure the number of columns. Configure the cursor to
** think that the table has one more column than it really
@@ -197,8 +201,8 @@ int sqlite3_blob_open(
** we can invoke OP_Column to fill in the vdbe cursors type
** and offset cache without causing any IO.
*/
- sqlite3VdbeChangeP4(v, 2+flags, SQLITE_INT_TO_PTR(pTab->nCol+1),P4_INT32);
- sqlite3VdbeChangeP2(v, 6, pTab->nCol);
+ sqlite3VdbeChangeP4(v, 3+flags, SQLITE_INT_TO_PTR(pTab->nCol+1),P4_INT32);
+ sqlite3VdbeChangeP2(v, 7, pTab->nCol);
if( !db->mallocFailed ){
sqlite3VdbeMakeReady(v, 1, 1, 1, 0);
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-19 19:06:15 +0000