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Remove the BtreeMutexArray object - use the Vdbe.btreeMask field to accomplish

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the same result.  Add a generation counter to btree mutexes in order to assert
that mutexes are never temporarily dropped over a range of instructions in order
to do deadlock avoidance in some subroutine.  Lock all btrees in any Vdbe
program that uses OP_ParseSchema.

FossilOrigin-Name: d81708f7d1eee399bfe76f6b8dac950a85dc2582
This commit is contained in:
drh
2011-04-04 00:14:43 +00:00
parent dddd779b2b
commit bdaec52c62
8 changed files with 242 additions and 198 deletions
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81
src/vdbe.c
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@@ -571,7 +571,7 @@ int sqlite3VdbeExec(
/*** INSERT STACK UNION HERE ***/
assert( p->magic==VDBE_MAGIC_RUN ); /* sqlite3_step() verifies this */
sqlite3VdbeMutexArrayEnter(p);
sqlite3VdbeEnter(p);
if( p->rc==SQLITE_NOMEM ){
/* This happens if a malloc() inside a call to sqlite3_column_text() or
** sqlite3_column_text16() failed. */
@@ -1394,6 +1394,7 @@ case OP_Function: {
ctx.pColl = pOp[-1].p4.pColl;
}
(*ctx.pFunc->xFunc)(&ctx, n, apVal); /* IMP: R-24505-23230 */
sqlite3VdbeMutexResync(p);
if( db->mallocFailed ){
/* Even though a malloc() has failed, the implementation of the
** user function may have called an sqlite3_result_XXX() function
@@ -1404,6 +1405,17 @@ case OP_Function: {
goto no_mem;
}
/* The app-defined function has done something that as caused this
** statement to expire. (Perhaps the function called sqlite3_exec()
** with a CREATE TABLE statement.)
*/
#if 0
if( p->expired ){
rc = SQLITE_ABORT;
break;
}
#endif
/* If any auxiliary data functions have been called by this user function,
** immediately call the destructor for any non-static values.
*/
@@ -2650,6 +2662,7 @@ case OP_Savepoint: {
if( p1==SAVEPOINT_ROLLBACK && (db->flags&SQLITE_InternChanges)!=0 ){
sqlite3ExpirePreparedStatements(db);
sqlite3ResetInternalSchema(db, 0);
sqlite3VdbeMutexResync(p);
db->flags = (db->flags | SQLITE_InternChanges);
}
}
@@ -2940,6 +2953,7 @@ case OP_VerifyCookie: {
*/
if( db->aDb[pOp->p1].pSchema->schema_cookie!=iMeta ){
sqlite3ResetInternalSchema(db, pOp->p1);
sqlite3VdbeMutexResync(p);
}
p->expired = 1;
@@ -4622,29 +4636,22 @@ case OP_ParseSchema: {
char *zSql;
InitData initData;
/* Any prepared statement that invokes this opcode will hold mutexes
** on every btree. This is a prerequisite for invoking
** sqlite3InitCallback().
*/
#ifdef SQLITE_DEBUG
for(iDb=0; iDb<db->nDb; iDb++){
assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );
}
#endif
assert( p->btreeMask == ~(yDbMask)0 );
iDb = pOp->p1;
assert( iDb>=0 && iDb<db->nDb );
/* When this opcode is invoked, it is guaranteed that the b-tree mutex
** is held and the schema is loaded for database iDb. However, at the
** start of the sqlite3_exec() call below, SQLite will invoke
** sqlite3BtreeEnterAll(). If all mutexes are not already held, the iDb
** mutex may be temporarily released to avoid deadlock. If this happens,
** then some other thread may delete the in-memory schema of database iDb
** before the SQL statement runs. The schema will not be reloaded because
** the db->init.busy flag is set. This can result in a "no such table:
** sqlite_master" or "malformed database schema" error being returned to
** the user.
**
** To avoid this, obtain all mutexes and check that no other thread has
** deleted the schema before calling sqlite3_exec(). If we find that the
** another thread has deleted the schema, there is no need to update it.
** The updated schema will be loaded from disk when it is next required.
*/
assert( sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );
assert( DbHasProperty(db, iDb, DB_SchemaLoaded) );
sqlite3BtreeEnterAll(db);
if( DbHasProperty(db, iDb, DB_SchemaLoaded) ){
/* Used to be a conditional */ {
zMaster = SCHEMA_TABLE(iDb);
initData.db = db;
initData.iDb = pOp->p1;
@@ -4665,7 +4672,6 @@ case OP_ParseSchema: {
db->init.busy = 0;
}
}
sqlite3BtreeLeaveAll(db);
if( rc==SQLITE_NOMEM ){
goto no_mem;
}
@@ -5190,11 +5196,25 @@ case OP_AggStep: {
ctx.pColl = pOp[-1].p4.pColl;
}
(ctx.pFunc->xStep)(&ctx, n, apVal); /* IMP: R-24505-23230 */
sqlite3VdbeMutexResync(p);
if( ctx.isError ){
sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(&ctx.s));
rc = ctx.isError;
}
/* The app-defined function has done something that as caused this
** statement to expire. (Perhaps the function called sqlite3_exec()
** with a CREATE TABLE statement.)
*/
#if 0
if( p->expired ){
rc = SQLITE_ABORT;
break;
}
#endif
sqlite3VdbeMemRelease(&ctx.s);
break;
}
@@ -5216,8 +5236,11 @@ case OP_AggFinal: {
pMem = &aMem[pOp->p1];
assert( (pMem->flags & ~(MEM_Null|MEM_Agg))==0 );
rc = sqlite3VdbeMemFinalize(pMem, pOp->p4.pFunc);
sqlite3VdbeMutexResync(p);
if( rc ){
sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(pMem));
}else if( p->expired ){
rc = SQLITE_ABORT;
}
sqlite3VdbeChangeEncoding(pMem, encoding);
UPDATE_MAX_BLOBSIZE(pMem);
@@ -5294,7 +5317,7 @@ case OP_JournalMode: { /* out2-prerelease */
/* This opcode is used in two places: PRAGMA journal_mode and ATTACH.
** In PRAGMA journal_mode, the sqlite3VdbeUsesBtree() routine is called
** when the statment is prepared and so p->aMutex.nMutex>0. All mutexes
** when the statement is prepared and so p->btreeMask!=0. All mutexes
** are already acquired. But when used in ATTACH, sqlite3VdbeUsesBtree()
** is not called when the statement is prepared because it requires the
** iDb index of the database as a parameter, and the database has not
@@ -5303,12 +5326,11 @@ case OP_JournalMode: { /* out2-prerelease */
** No other mutexes are required by the ATTACH command so this is safe
** to do.
*/
assert( (p->btreeMask & (((yDbMask)1)<<pOp->p1))!=0 || p->aMutex.nMutex==0 );
if( p->aMutex.nMutex==0 ){
if( p->btreeMask==0 ){
/* This occurs right after ATTACH. Get a mutex on the newly ATTACHed
** database. */
sqlite3VdbeUsesBtree(p, pOp->p1);
sqlite3VdbeMutexArrayEnter(p);
sqlite3VdbeEnter(p);
}
pBt = db->aDb[pOp->p1].pBt;
@@ -5946,13 +5968,16 @@ vdbe_error_halt:
sqlite3VdbeHalt(p);
if( rc==SQLITE_IOERR_NOMEM ) db->mallocFailed = 1;
rc = SQLITE_ERROR;
if( resetSchemaOnFault ) sqlite3ResetInternalSchema(db, 0);
if( resetSchemaOnFault ){
sqlite3ResetInternalSchema(db, 0);
sqlite3VdbeMutexResync(p);
}
/* This is the only way out of this procedure. We have to
** release the mutexes on btrees that were acquired at the
** top. */
vdbe_return:
sqlite3BtreeMutexArrayLeave(&p->aMutex);
sqlite3VdbeLeave(p);
return rc;
/* Jump to here if a string or blob larger than SQLITE_MAX_LENGTH