[Swift-user] How to wait on functions that return no data?

[Mihael Hategan]

On Tue, 2008-03-25 at 09:46 -0500, Michael Wilde wrote:
> For the petro-model app Im working on, it would be interesting to run 
> the parameter sweep in "map reduce" manner, in which each invocation 
> bites off a portion of the parameter space and processes it, resulting 
> in a set of result tuples. Each run of the model will produce a set of 
> tuples, and when all are done, we want to aggregate and plot the tuples.
> 
> While with batching this is not strictly needed, it would be interesting 
> to let the model results accumulate on the local filesystem (as in this 
> case they are small) and collect them either at the end of the run, or 
> periodically and perhaps asynchronously during the run.
> 
> To do this, we'd want to write the model invocation as a swift function 
> with only scalar numeric parameters, and no output.

That assertion I'm not sure about.

> 
> The question is how to call a zero-returns function in a swift foreach() 
> loop, and embed that foreach() in a function that doesnt return until 
> all members of the foreach() have been processed.

The very notion of "return" as it would appear in a strict language
doesn't make much sense in Swift, so I'm not quite sure.

> 
> I havent tried to code this yet, because I cant think of a way to 
> express it in swift, due to the data-dependency semantics.
> 
> In the example below, I want collectResults() to get invoked after all 
> the runam() calls complete in doall().

results = doall();
collectResults(results);

Mihael

> 
> Anyone have any ideas?
> 
> This is a low-priority question, just food for thought, as the batched 
> way of running this parameter sweep should be straightforward and efficient.
> 
> Mike
> 
> 
> 
> // Amiga-Mars Parameter Sweep
> 
> type amout;
> 
> runam (string id , string p1, string p2) // no ret val
> {
>    app { runam3 id p1 p2 ; }
> }
> 
> type params {
>    string id;
>    string p1;
>    string p2;
> };
> 
> doall(params p[])
> {
>    foreach pset in p {
>      runam(pset.id, pset.p1, pset.p2);
>    }
>    // waitTillAllDone();
>    // want to block here till all above finish,
>    // but no data to wait on.  any way to
>    // achieve this???
> }
> 
> // Main
> 
> params p[];
> p = readdata("paramlist");
> doall(p);
> amout amdata <some mapping>;
> amdata = collectResults();
> 
> // ^^^ Want collectresults to run AFTER all runam() calls finish
> //     in the doall() function.
> 
> 
> 
> 
> 
> 
> _______________________________________________
> Swift-user mailing list
> Swift-user at ci.uchicago.edu
> http://mail.ci.uchicago.edu/mailman/listinfo/swift-user
>