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

Mon Mar 7 14:39:21 EST 2016

2016-03-07 20:35 GMT+01:00 Reza Rahman <reza_rahman at lycos.com>:

> Talking with a colleague about this he reminded me of an important fact I
> almost forgot. The CompletableFuture API can actually be used with custom
> executors. That means users concerned about managed threads in a Java EE
> environment can use it with existing EE 7 concurrency executors.
>
> Basically this means CompletableFutures are already pretty Java EE ready.
>
> If this is the main cited reason for using CompletionStage, is it really
> that valid of an argument to justify yet another custom subclass specific
> only to CDI instead of what's likely to be far more familiar and expected?
>
>
Did he mention it is true for *created* comlpetion future which is not the
case for async events? But this is a good point to not add anything to CDI:
the feature is a one liner *already*.


> On Mar 7, 2016, at 8:11 AM, Reza Rahman <reza_rahman at lycos.com> wrote:
>
> I think this is a very bad idea. It's better not to use either API and
> wait to sort out how CompletableFuture can be used in EE consistently.
> Because of backwards compatibility rules, it is better to have no API than
> a bad API.
>
> On Mar 7, 2016, at 3:45 AM, Romain Manni-Bucau <rmannibucau at gmail.com>
> wrote:
>
> 2016-03-07 9:07 GMT+01:00 Martin Kouba <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>> 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
> - 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)
>
>
>>
>>>  >
>>>  >>
>>>  >> 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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>>>  >>
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>>>  >>
>>>  >
>>>  > --
>>>  > Martin Kouba
>>>  > Software Engineer
>>>  > Red Hat, Czech Republic
>>>
>>>
>> --
>> Martin Kouba
>> Software Engineer
>> Red Hat, Czech Republic
>>
>
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