run method
Process a WorkerMessage
on the pool.
Implementation
Future<WorkerResponse> run(WorkerMessage msg) {
if (nextWorker >= workers.length) {
nextWorker = 0;
}
WorkerHandle worker = workers[nextWorker];
worker.send(msg);
nextWorker += 1;
return worker.rx.next.then((value) => value as WorkerResponse);
}