[DGD] priority of user/network i/o vs callouts

[Raymond Jennings]

How many user I/O events are handled between each callout batch?

>From the code it *looks* like only one I/O event per batch, but did I read
the code correctly?

On Sun, Feb 16, 2014 at 7:59 AM, Felix A. Croes <felix at dworkin.nl> wrote:

> Raymond Jennings <shentino at gmail.com> wrote:
>
> > I remember one time you said you'd refuse any patches that rearranged
> > things so that callouts were pushed behind user i/o or something.
> >
> > Did I get that right, and if so...why is dgd's design based on this
> > relative priority?
> >
> > My personal choice would be to have interrupts at top priority, then
> > handling i/o, then callouts, and finally housekeeping.
>
> Interrupts in DGD are triggered by kill signals.  Signals are a
> rudimentary form of inter-process communication, and as such they are
> a very poor choice for the highest priority.
>
> Callouts must have higher priority than user input because there will
> be many callouts for each user command; this is not true for the classic
> mudlibs, but it is true for modern ones (e.g. Discworld) and for non-mud
> uses.  Callouts are already kept in check by the fact that they are
> run in batches, and a callout started from one batch will not execute
> until the next batch at the earliest, with user input handled in between
> those batches.
>
> The idea that callouts should have lower priority than user input is
> prompted by the notion that admins can login and stop callout explosions.
> That doesn't really work anyway, and callout explosions are best prevented
> in a different way, for instance by imposing resource limits.
>
> Regards,
> Felix Croes
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