`select` statement for Java

[Alex Otenko]

It's not the same as blocking on N queues. That consumes N elements.

Select consumes one element from some queue. It's like blocking on N
queues, then push back N-1 elements before anyone else gets anything from
those queues.

Alex

On Tue, 4 Feb 2020, 08:42 Dávid Karnok, <akarnokd at gmail.com> wrote:

> What do you mean "multiple streams of events"? Merging them, zipping them,
> combining them?
>
> > blocking on multiple `BlockingQueue`
>
> My impression about Loom is that most operators, especially multi-valued
> streams, are DIY. So blocking on multiple queues means you block on each in
> its own virtual thread, then enqueue the object on another blocking queue
> which you block for on the end consumer virtual thread. The complication
> is, as with Flow.Publishers, when the number of input queues is dynamic,
> how to propagate errors and indicate termination.
>
>
> Doug Lea <dl at cs.oswego.edu> ezt írta (időpont: 2020. febr. 4., K, 1:33):
>
> > On 2/3/20 1:38 PM, Ryan Schmitt wrote:
> > > Are there any current or planned constructs in Java that allow blocking
> > on
> > > multiple streams of events simultaneously, similar to the `select`
> > > statement in Go? I realize that technically speaking this is probably
> > > orthogonal to Loom, but it seems like an important capability in order
> to
> > > get the most out of the blocking, imperative thread abstraction that
> Loom
> > > is fundamentally about.
> > >
> >
> > Yes. We've been contemplating adding to java.util.concurrent a
> > Loom-friendly channel-like component with select-like capabilities. I
> > hope to write more about this in the coming months when it gets concrete
> > enough to ask for feedback. For now: the most likely name is "Carrier",
> > to distinguish from other channels and queues in Java.
> >
> > As others have noted, there's not likely to be special syntax, but the
> > new pattern-match constructs should serve well. As in:
> > switch(selector.receive()) { case Request r -> service(r); ... }
> >
> > -Doug
> >
> >
> >
> >
>
> --
> Best regards,
> David Karnok
>