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

[Michael Wilde]

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.

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.

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().

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.