[cdi-dev] async: back to completion future?

[Martin Kouba]

Dne 7.3.2016 v 11:10 Romain Manni-Bucau napsal(a):
>
> 2016-03-07 10:57 GMT+01:00 Martin Kouba <mkouba at redhat.com
> <mailto:mkouba at redhat.com>>:
>
>     Dne 7.3.2016 v 09:45 Romain Manni-Bucau napsal(a):
>
>         2016-03-07 9:07 GMT+01:00 Martin Kouba <mkouba at redhat.com
>         <mailto:mkouba at redhat.com>
>         <mailto:mkouba at redhat.com <mailto:mkouba at redhat.com>>>:
>
>
>              Dne 7.3.2016 v 09:03 Romain Manni-Bucau napsal(a):
>
>
>                  Le 7 mars 2016 08:35, "Martin Kouba" <mkouba at redhat.com
>         <mailto:mkouba at redhat.com>
>                  <mailto:mkouba at redhat.com <mailto:mkouba at redhat.com>>
>                  <mailto:mkouba at redhat.com <mailto:mkouba at redhat.com>
>         <mailto:mkouba at redhat.com <mailto:mkouba at redhat.com>>>> a écrit :
>
>                    >
>                    > Dne 6.3.2016 v 15:39 Romain Manni-Bucau napsal(a):
>                    >
>                    >> Hi guys,
>                    >>
>                    >> as a user having a ComlpetionStage makes me loose
>         some JDK
>                  utilities,
>                    >> can we move back to CompletionFuture?
>                    >>
>                    >> It would allow for instance:
>                    >>
>                    >> // doesn't work with CompletionStage
>                    >> CompletionFuture.allOf(event1.fireAsync(...),
>                  event2.fireAsync(...))
>                    >>        .then(...)
>                    >
>                    >
>                    > Well, this should work if the underlying
>         CompletionStage impl
>                  supports toCompletableFuture(), i.e. in Weld 3:
>                    >
>
>                  Yes but it is not natural to convert it IMO = we can do
>         better
>
>                    >
>
>         CompletableFuture.allOf(event1.fireAsync(...).toCompletableFuture(),
>                  event2.fireAsync(...).toCompletableFuture())
>                    >
>                    > AFAIK the default async execution facility of
>                  CompletableFuture is
>                  ForkJoinPool.commonPool() which is not a good fit for
>         Java EE.
>                  Using the
>                  CompletionStage interface allows us to wrap the async calls
>                  without the
>                  specified executor (e.g.
>                  CompletionStage.thenApplyAsync(Function<? super
>                  T, ? extends U>)) and supply a default one provided by
>         the impl.
>                    >
>
>                  Should use the pool in which the evznt is fired then
>         "then step" is
>                  synchronous is my sample so all is decided at fire time
>
>
>              I don't talk about your particular example - I understand
>         that it's
>              not using async exec (although the "then()" method does not
>         exist).
>
>
>         was supposed to represent the different flavours (thenRun,
>         thenCompose,
>         ...) ;).
>
>         That said I agree on the state switching the pool is better but with
>         these 2 notes:
>
>         - could be better to hide these poorly designed methods then ->
>         don't
>         use CompletionXXX but a CDI API with a bridge to CompletionX to
>         let the
>         user go back on SE tools
>
>
>     Yep, this is one of the possible solutions. On the other hand, I
>     don't think it's poorly designed. CompletionStage defines the
>     "default asynchronous execution facility" and CDI spec states that
>     the CompletionStage returned by fireAsync methods is
>     container-specific. The impl may choose to clarify this "default
>     asynchronous execution facility", i.e. there's place for innovation...
>
>         - we still don't have a *standard* config for the pool(s)
>         underlying CDI
>         features so it sounds as poor as SE solution IMO (at least a
>         core/max/ttl config in beans.xml)
>
>
>     I don't think this should be standardized...
>
>
> Why? Typically if you take @Asynchronous (EJB spec) you have already
> this issue and this is often avoided when portability matters for that
> particular reason you don't know how you will behave. Or do you think
> concurrency-utilities solves it?

No, it doesn't. I think it should remain impl-specific. You know how it 
will behave - it will be async. And if needed you could tune up the 
config, depending on the container. If you specify core/max/ttl the 
container will not be able to optimize.

>
>
>
>                    >
>                    >>
>                    >> Romain Manni-Bucau
>                    >> @rmannibucau <https://twitter.com/rmannibucau> | Blog
>                    >> <http://rmannibucau.wordpress.com> | Github
>                    >> <https://github.com/rmannibucau> | LinkedIn
>                    >> <https://www.linkedin.com/in/rmannibucau> | Tomitriber
>                    >> <http://www.tomitribe.com>
>                    >>
>                    >>
>                    >>
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>                    >
>                    > --
>                    > Martin Kouba
>                    > Software Engineer
>                    > Red Hat, Czech Republic
>
>
>              --
>              Martin Kouba
>              Software Engineer
>              Red Hat, Czech Republic
>
>
>
>     --
>     Martin Kouba
>     Software Engineer
>     Red Hat, Czech Republic
>
>

-- 
Martin Kouba
Software Engineer
Red Hat, Czech Republic