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

[Romain Manni-Bucau]

2016-03-07 10:57 GMT+01:00 Martin Kouba <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>>:
>>
>>
>>     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>>> 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?


>
>>
>>           >
>>           >>
>>           >> 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
>
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