[ZODB-Dev] Problem with Bsddb3Storage.copyTransactionsFrom

[Barry A. Warsaw]

>>>>> "JH" =3D=3D Jeremy Hylton <jeremy@zope.com> writes:

    JH> I think we should support None.  Take a look at line 157 of
    JH> ZODB/DB.py.  It's the transaction that creates the root object
    JH> in an empty storage.  It uses None.

Duh.  I need to get my eyes examined; Full supports this of course!

Here's the test case I added to verify this:

-------------------- snip snip --------------------BasicStorage.py
    def checkSerialIsNoneForInitialRevision(self):
        eq =3D self.assertEqual
        oid =3D self._storage.new_oid()
        txn =3D self._transaction
        self._storage.tpc_begin(txn)
        # Use None for serial.  Don't use _dostore() here because that =
coerces
        # serial=3DNone to serial=3DZERO.
        newrevid =3D self._storage.store(oid, None, zodb_pickle(MinPO(1=
1)),
                                       '', txn)
        self._storage.tpc_vote(txn)
        self._storage.tpc_finish(txn)
        data, revid =3D self._storage.load(oid, '')
        value =3D zodb_unpickle(data)
        eq(value, MinPO(11))
        eq(revid, newrevid)
-------------------- snip snip --------------------

Full passes this test, but ZEO with FileStorage does not:

-------------------- snip snip --------------------
FAIL: checkSerialIsNoneForInitialRevision (ZEO.tests.testZEO.ZEOFileSto=
rageTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "lib.linux-i686-2.1/ZODB/tests/BasicStorage.py", line 83, in che=
ckSerialIsNoneForInitialRevision
    eq(revid, newrevid)
  File "/usr/local/lib/python2.1/unittest.py", line 273, in failUnlessE=
qual
    raise self.failureException, (msg or '%s !=3D %s' % (first, second)=
)
AssertionError: =03@h[o=D1G; !=3D None
-------------------- snip snip --------------------

I'm getting a bunch of other failures in ZEOFileStorageTest and
testBTrees with current CVS, too though.

I wasn't very clear in my previous message:

>>>>> "BAW" =3D=3D Barry A Warsaw <barry@zope.com> writes:

    BAW> For some reason, your script is passing a None to the serial
    BAW> argument to store() and you're getting a conflict that
    BAW> tryToResolveConflict() is unable to resolve.  Full then wants
    BAW> to raise a ConflictError, but it tries unconditionally to
    BAW> stringify the serial via utils.U64().  That doesn't work when
    BAW> passing in None.

    BAW> This doesn't explain why None is getting passed in though.

What is /really/ happening is that for some reason your storage
already has a revision for the object, so its old serial number exists
-- i.e. the object is /not/ being created, but None is still being
passed in for the serial argument.  /That/ is what doesn't make sense!

Passing serial=3DNone for object creation is no problem.  But you will
get a conflict error if serial=3DNone when the object already has
revisions in the storage.  That seems as it should be.

-Barry