[Zope3-dev] buildbot failure in Zope3 trunk 2.4 FreeBSD tmiddleton

[Christian Theune]

Hi,

Tim Peters wrote:
> [Christian]
>> Thanks for the clarification, Tim!
> 
> You're welcome :-)
> 
>> Due to the possible future use of 64-bit BTrees, I'm inclined to go for
>> the 2-character fix for now and possibly remove it once we hit 64-bit
>> everywhere.

Yupp. If we remember ... ;)

> The BTree bug and the intid bug are quite distinct.  intid should be
> repaired regardless, and is easy to repair.  The only reason the BTree
> bug got sucked into this is because an overly-elaborate way of
> repairing the intid bug bashed into the BTree bug (the elaborate initd
> fix reasonably assumed that Ix BTrees would complain if you tried to
> store a key they can't actually handle, but in fact they don't always
> complain).  All the _simple_ ways of repairing intid avoid the BTree
> bug.

Which is ok with me ... and is what I did.

> In a 64-bit-everywhere world, presumably intid will want to change to
> use an id range substantially larger than 31 bits anyway.
> 
> BTW, note that the simple intid fixes are essentially untestable, and
> for the same reason you can't actually write a convincing test now
> that _shows_ that the current (pre-patch) intid is buggy.  There are
> only 2 return values (out of 2**31+1 current possible outcomes) that
> create a problem, so it's a one-in-a-billion chance of screwing up.
> The simple fixes just remove (exactly) those two problem cases.  It's
> trivial to prove that the current intid has that bug, and
> substantially harder to prove that the 2-character fix repairs it (but
> trivial to prove that my original suggestion repairs it), but it's
> very much harder to write a test showing either the bug or its
> absence.

Right. The test that I wrote merely checks that the border case of 
2**31-1 is applied correctly and assumes all smaller numbers to work 
fine. :)

This finally works on 32- and 64-bit machines.

Christian

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