On Jan 23, 11:24 am, e <evier...@gmail.com> wrote:
> wow. I wonder if I could use this for the quicksort I was talking about.
Interesting question. I can't think of an elegant way to implement an
agent based parallel quicksort because await cannot be used
recursively. So I implemented a version using Futures instead. Now you
wont be able to run this unless you modify Agent.java, search for
soloExectuor, make it public, and recompile Clojure.
http://groups.google.com/group/clojure/web/pquicksort.clj
Using futures like this seems convenient to me, I think it has some
benefits over just using a Thread (two pools to choose from, you can
wait for a return, you can cancel it) and making a one-shot agent just
feels a bit messy.
On Jan 23, 4:06 am, Emeka <emekami...@gmail.com> wrote:
> Could you explain atoms the way you explained agents?\
Atoms provide a place to put some data. Multiple threads can update or
read this data without fear of it be 'half' updated by two threads
accessing it at once. Further more, modification of Atoms is only
available via supplying a function which takes the current value and
returns a new value. The reason for this is that even with a piece of
atomic data, if you had two threads execute A = A + A * A at the same
time, one might update A while the other was half way through its
calculation, so on the second thread it might be something like this:
Anew = Abefore + Abefore * Aafter
That would be really confusing!
So instead you update atoms by providing a fuction (swap! A (fn [x] (x
+ x * x))
A will only be set when the entire calculation has been made without A
changing in the meantime.
This is in contrast to Refs, which use transactions to coordinate
access.
Regards,
Tim.
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