[cdi-dev] inheritance of cdi scopes
Reza Rahman
reza_rahman at lycos.com
Sun Mar 6 17:33:02 EST 2016
This is fair, although probably rare in practice. The utilities I do think mostly assume a read-only context that does not change from thread to thread.
> On Mar 6, 2016, at 5:23 PM, Mark Struberg <struberg at yahoo.de> wrote:
>
> Also keep in mind that the request scoped instances are mostly not thread safe.
> Lg,
> Strub
>
>> Am 06.03.2016 um 20:15 schrieb Romain Manni-Bucau <rmannibucau at gmail.com>:
>>
>>
>> 2016-03-06 19:42 GMT+01:00 Reza Rahman <reza_rahman at lycos.com>:
>>> This frankly surprises me. I'll check the specification text. This might indeed just be an implementation bug. The EE concurrency utilities are supposed to be copying all relevant context. If this is an issue than it has to be that it is not copying enough of the HTTP request context for CDI to work.
>>
>> The issue is not technical since I got it working but needed to reverse. From my understanding ee concurrency utilities was done in a time CDI was not there so it just ignored it somehow and it hasnt been updated when integrated to the spec. Now with the wording of the CDI - and TCK - it is impossible to make it working since request scope is bound the thre request thread - and not the request. Side note: same applies to session scope and conversation.
>>
>>> Surely the Red Hat folks can quickly shed some light here since they implement essentially this whole stack?
>>>
>>>> On Mar 6, 2016, at 1:30 PM, Romain Manni-Bucau <rmannibucau at gmail.com> wrote:
>>>>
>>>> 2016-03-06 19:20 GMT+01:00 Reza Rahman <reza_rahman at lycos.com>:
>>>>> Can you kindly try to make the example a bit simpler? It's important to make the case for how likely this is supposed to occur in most business applications.
>>>>>
>>>>> Also, other than making sure that the executor service is propagating thread local request contexts correctly what other solution are you proposing? Did you check the specification? How sure are you that this isn't simply an implementation bug?
>>>>>
>>>>> As far as I know the executor service is supposed to be preserving all relevant parts of the EE context?
>>>>
>>>> Not in concurrency-utilities for EE at least. That was the first impl I did then Mark pointed out it was violating CDI spec and request scope definition. There is a kind of contracdiction there cause concurrency-utilities doesn't integrate with CDI at all but we can also see it the opposite way: CDI doesn't provide any way to propagate a context in another thread. Both point of view are valid so we need to see where we tackle it.
>>>>
>>>>>> On Mar 6, 2016, at 12:35 PM, Romain Manni-Bucau <rmannibucau at gmail.com> wrote:
>>>>>>
>>>>>> does https://gist.github.com/rmannibucau/d55fce47b001185dca3e help?
>>>>>>
>>>>>> Idea is to give an API to make:
>>>>>>
>>>>>> public void complete() {
>>>>>> try {
>>>>>> asyncContext.complete();
>>>>>> } finally {
>>>>>> auditContext.end();
>>>>>> }
>>>>>> }
>>>>>>
>>>>>> working without hacky and almost impossible context pushing (cause of injections nature you are not supposed to know what to push in the context when going async).
>>>>>>
>>>>>>
>>>>>>
>>>>>> Romain Manni-Bucau
>>>>>> @rmannibucau | Blog | Github | LinkedIn | Tomitriber
>>>>>>
>>>>>> 2016-03-06 16:40 GMT+01:00 Reza Rahman <reza_rahman at lycos.com>:
>>>>>>> Can you kindly share an annotated code example of the proposed solution so we can all follow and discuss this?
>>>>>>>
>>>>>>> On Mar 6, 2016, at 9:31 AM, Romain Manni-Bucau <rmannibucau at gmail.com> wroteshar:
>>>>>>>
>>>>>>>> Hi guys,
>>>>>>>>
>>>>>>>> spoke on concurrency utilities about the ability to inherit a cdi scope. Idea is to follow request scope more than cdi spec allows. First thought it was a concurrency utilities thing but Reza mentionned can be a CDI one so here it is.
>>>>>>>>
>>>>>>>> Sample:
>>>>>>>> In a servlet i get MyBean which is @RequestScoped, I do some set on it. The i go async (AsyncContext) and trigger a task in another thread. It would be neat - and mandatory in some case by the loose coupling nature of CDI - to get the *same* MyBean *instance* in this thread. With a direct dependency you can easily use message passing pattern - but you loose the loose coupling cause you need to know until which level you unwrap, think t principal case which has 2-3 proxies!. However in practice you have a lot of undirect dependencies, in particular with enterprise concerns (auditing, security...) so you can't really do it easily/naturally.
>>>>>>>>
>>>>>>>> Bonus:
>>>>>>>> One very verbose way is to be able to kind of push/pop an existing context in a thread - wrappers doing it on a Runnable/Consumer/Function/... would be neat.
>>>>>>>>
>>>>>>>> Question:
>>>>>>>> Would CDI handle it in 2.0?
>>>>>>>>
>>>>>>>> Side note: this is really about the fact to reuse a "context context" (its current instances map) in another thread the more transparently possible and match the user vision more than a technical question for now.
>>>>>>>>
>>>>>>>>
>>>>>>>> Romain Manni-Bucau
>>>>>>>> @rmannibucau | Blog | Github | LinkedIn | Tomitriber
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