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<H1>[MUD-Dev] Re: atomic functions</H1>
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<LI><em>To</em>: <A HREF="mailto:mud-dev#kanga,nu">mud-dev#kanga,nu</A></LI>
<LI><em>Subject</em>: [MUD-Dev] Re: atomic functions</LI>
<LI><em>From</em>: "Felix A. Croes" <<A HREF="mailto:felix#xs1,simplex.nl">felix#xs1,simplex.nl</A>></LI>
<LI><em>Date</em>: Sun, 3 May 1998 01:23:43 +0200 (MET DST)</LI>
<LI><em>Reply-To</em>: <A HREF="mailto:mud-dev#kanga,nu">mud-dev#kanga,nu</A></LI>
<LI><em>Sender</em>: "Petidomo List Agent -- Kanga.Nu version" <<A HREF="mailto:petidomo#kanga,nu">petidomo#kanga,nu</A>></LI>
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<PRE>
Jon A. Lambert <jlsysinc#ix,netcom.com> wrote:
> On 1 May 98 at 13:26, Shawn Halpenny wrote:
> >
> > So atomic fragments are akin to critical sections? For me, methods can
> > execute in their own context (essentially the call stack of an event's
> > processing is an entire critical section). Since they receive current
> > copies of any data they touch, rather than having to wait for it to
> > become available, though, there's no waiting upon entry. Given the way
> > I've structured things, atomic fragments don't add much benefit (but see
> > below).
> >
>
> There are a couple of issues here, asynchronous event execution and
> data currency/integrity. In looking at his model, it appears to be an
> example of how data currency/integrity issues would be handled at the MPL
> (or LPC) level. I'm not sure yet how his events are generated.
My server is a rewrite from scratch of LPmud, so events can be
generated in two different ways: a status change for a socket
(connection available/input available/output done/connection lost)
or with the infamous "call_out" function. I would like to rename
the latter to something that makes more sense, but at this point
I am bound to backward compatibility.
I mean to have both asynchronous event execution and data
currency/integrity. The interesting part is that the same
code can be used for both.
> > Explicitly defining an atomic function would require more programmer
> > work. In a free user programming environment, I don't want to require
> > people to decide whether the function they just wrote to make their
> > sword talk needs to be atomic or have atomic sections within it. For
> > now, I'm opting to leave it up to the server to decide the atomicity of
> > things (which it does by way of the event and DB models). An
> > experienced programmer can probably outdo the server if given the
> > capability to declare atomic blocks, but a newbie would be more
> > inclined to either not declare them at all (in which case, I'd have to
> > rely on a system like I've already got in mind) or declare them poorly
> > and result in performance worse than the server would obtain doing it
> > itself.
>
> Exactly so. Providing for explicit data currency in the language makes
> it a much more powerful tool, although there is the side-effect that
> programming for data currency is more complex.
>
> I've taken a similar position to yours, where data currency is implicitly
> linked to event atomicity (is that a word?).
Atomicity? Atomicness?
> My event method call() is
> the explicit way of declaring that data currency is NOT important or
> non-critical. Perhaps the semantic opposite of Felix's model?
I don't understand this.
> Thus an Event may be made up of many methods/functions, all of which must
> succeed for the event to commit. Methods may schedule additional Events
> and these events will be scheduled regardless of whether the generating
> Event succeeds or not. So in many cases, Event calls will be obviously
> be placed just before the successful return of the top-most method.
> There is a caveat. A method/function which is called as an event
> should ensure that it checks the state of the caller/callee for state
> validity. Nothing comes for free. I have just shuffled the complexity
> into another area of program design. I have a theory this might be
> unavoidable. :(
Hmm. That is one thing I mean to do differently: if the current
event fails to commit, then any events generated by it are unscheduled.
Felix
--
MUD-Dev: Advancing an unrealised future.
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<ul compact><li><em>From:</em> "Jon A. Lambert" <jlsysinc#ix,netcom.com></li></ul>
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<ul><li>Thread context:
<BLOCKQUOTE><UL>
<LI><STRONG>[MUD-Dev] Re: atomic functions</STRONG>, <EM>(continued)</EM>
<ul compact>
<ul compact>
<LI><strong><A NAME="00331" HREF="msg00331.html">[MUD-Dev] Re: atomic functions</A></strong>,
Jon A. Lambert <a href="mailto:jlsysinc#ix,netcom.com">jlsysinc#ix,netcom.com</a>, Sat 02 May 1998, 18:16 GMT
</LI>
</ul>
<LI><strong><A NAME="00420" HREF="msg00420.html">[MUD-Dev] Re: atomic functions</A></strong>,
J C Lawrence <a href="mailto:claw#under,engr.sgi.com">claw#under,engr.sgi.com</a>, Wed 06 May 1998, 17:39 GMT
</LI>
<LI><strong><A NAME="00333" HREF="msg00333.html">[MUD-Dev] Re: atomic functions</A></strong>,
Felix A. Croes <a href="mailto:felix#xs1,simplex.nl">felix#xs1,simplex.nl</a>, Sat 02 May 1998, 23:25 GMT
</LI>
<LI><strong><A NAME="00334" HREF="msg00334.html">[MUD-Dev] Re: atomic functions</A></strong>,
Felix A. Croes <a href="mailto:felix#xs1,simplex.nl">felix#xs1,simplex.nl</a>, Sat 02 May 1998, 23:26 GMT
</LI>
<LI><strong><A NAME="00335" HREF="msg00335.html">[MUD-Dev] Re: atomic functions</A></strong>,
Felix A. Croes <a href="mailto:felix#xs1,simplex.nl">felix#xs1,simplex.nl</a>, Sat 02 May 1998, 23:26 GMT
<UL>
<LI><strong><A NAME="00336" HREF="msg00336.html">[MUD-Dev] Re: atomic functions</A></strong>,
Jon A. Lambert <a href="mailto:jlsysinc#ix,netcom.com">jlsysinc#ix,netcom.com</a>, Sun 03 May 1998, 05:49 GMT
</LI>
</UL>
</LI>
<LI><strong><A NAME="00338" HREF="msg00338.html">[MUD-Dev] Re: atomic functions</A></strong>,
Chris Gray <a href="mailto:cg#ami-cg,GraySage.Edmonton.AB.CA">cg#ami-cg,GraySage.Edmonton.AB.CA</a>, Sun 03 May 1998, 17:16 GMT
<UL>
<LI><strong><A NAME="00344" HREF="msg00344.html">[MUD-Dev] Re: atomic functions</A></strong>,
Jon A. Lambert <a href="mailto:jlsysinc#ix,netcom.com">jlsysinc#ix,netcom.com</a>, Sun 03 May 1998, 15:19 GMT
</LI>
<LI><strong><A NAME="00399" HREF="msg00399.html">[MUD-Dev] Re: atomic functions</A></strong>,
Shawn Halpenny <a href="mailto:malachai#iname,com">malachai#iname,com</a>, Tue 05 May 1998, 14:32 GMT
</LI>
</UL>
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