Persistent Queue implementations?

[Aahz]

In article <aucseb$fb$1 at baldur.whoi.edu>,
Karl A. Krueger <kkrueger at example.edu> wrote:
>Aahz <aahz at pythoncraft.com> wrote:
>>
>> Just how much ACID do you need, anyway?
>
>Persistent queue operations need to be atomic, in order to be thread-
>safe.  Consistency is pretty much assumed since only single objects
>are being enqueued or dequeued.  Isolation is necessary only to the
>extent of blocking concurrent enqueues or dequeues.  And as for
>durability, well, this is supposed to be a persistent queue, not a drop-
>stuff-on-the-floor queue.

The question really is: what happens to dequeued objects that are not
fully processed (due to a system crash, say)?  That's why I was
suggesting a full-blown database, so that you can have a two-phase
commit.
-- 
Aahz (aahz at pythoncraft.com)           <*>         http://www.pythoncraft.com/

"I disrespectfully agree."  --SJM