[zeromq-dev] drop oldest

[Pieter Hintjens]

On Thu, Apr 12, 2012 at 12:32 PM, Ian Barber <ian.barber at gmail.com> wrote:

> It is worth noting that the oldest in many cases will be in the buffers of
> the transport, so you will in reality be dropping the oldest-in-zmq-space.
> There's a high chance of receiving some old messages on the other end.
> Still, might be a preferable option, but would need to be caveated in the
> documentation. I think there is a sensible abstraction somewhere (though
> fwiw MS wasn't too convinced) for flexible HWM code - there are regular
> requests for oldest first and credit based flow control, both of which are
> basically HWM policies. The ability to do rollups in the queued messages
> would also be beneficial for some applications.

Drop-oldest has to happen at the receiver to be safe.

All the things you're talking about are fairly doable in user space.
Perhaps worth exploring as a higher-level pub/sub pattern?

-Pieter