[Concurrency] Actors & actor isolation

[Douglas_Gregor]

@Lantua

I've been trying to figure this out. If I have an old custom executor, say DispatchQueue or some kind of RunLoop , and would like to wrap it as a (global) actor, how should I go about doing it? There don't seem to be a direct way to call async function from inside sync function, and old executor would accept only sync ones. Feels like it would need to open up PartialAsyncTask somehow.

PartialAsyncTask will have some kind of synchronous run() operation that should allow one to do this. For DispatchQueue, we will probably want to add some API to allow you to run an async operation on that particular queue. The details here will evolve as more of the pieces of the prototype implementation come together.

Doug