parallelFuture

[dsimcha]

I've created an alpha release of parallelFuture, a high-level parallelization
library for D2.  Right now, it has a task pool, futures, parallel foreach, and
parallel map.

Here's the (IMHO) coolest example:

auto pool = new ThreadPool();

// Assuming we have a function isPrime(), print all
// prime numbers from 0 to uint.max, testing for primeness
// in parallel.
auto myRange = iota(0, uint.max);
foreach(num; pool.parallel(myRange)) {
    if(isPrime(num)) {
        synchronized writeln(num);
    }
}

The interface is there and it seems to work, although it has not been
extensively stress tested yet.  Some of the implementation details could
admittedly use some cleaning up, and I would appreciate help from some
threading gurus on improving my queue (right now it's a naive synchronized
singly-linked list) and getting condition mutexes to work properly.  (Right
now, I'm using atomic polling followed by sleeping for 1 millisecond in a lot
of places.  It's a kludge, but it seems to work reasonably well in practice.)

The code is at:

http://dsource.org/projects/scrapple/browser/trunk/parallelFuture/parallelFuture.d

The docs are at:

http://cis.jhu.edu/~dsimcha/parallelFuture.html