[cdi-dev] Building EJB-like @Asynchronous via interceptor in CDI
Antonio Goncalves
antonio.goncalves at gmail.com
Sat Jan 17 10:30:49 EST 2015
@Arjan, remember the email I sent to the EE EG entitled "Status of the Java
EE 8 specifications". Bill Shannon replied :
*We agree on the long term vision. This is almost entirely a resource
issue. In order to do this, we have to stop doing something else, or we
have to delay the release. Based on the feedback we've gotten from the
community, the things we've chosen to work on right now are the most
important. We'd like to do what you suggest below as well, but it's most
likely going to have to be done later.*
So I don't know how we could "push" for an MR of the EE Concurrency spec.
Any idea ? Except harassing Bill to add resources to the EE Concurrency
spec and taking other resources out somewhere else... I don't know how we
could do this.
@Mark EE Concurreny could also add a @ThreadScoped like the one in Weld
(but with a EE meaning).
Antonio
On Sat, Jan 17, 2015 at 1:53 PM, Mark Struberg <struberg at yahoo.de> wrote:
> EE concurrency spec needs an update anyway. It currently doesn't
> explicitly require @RequestScoped beans to be supported on a new Thread.
> That breaks tons of frameworks and makes it barely usable in EE7.
>
> LieGrue,
> strub
>
> On Saturday, 17 January 2015, 13:12, arjan tijms <arjan.tijms at gmail.com>
> wrote:
>
>
> >
> >
> >Hi,
> >
> >
> >
> >On Sat, Jan 17, 2015 at 11:05 AM, Antonio Goncalves <
> antonio.goncalves at gmail.com> wrote:
> >
> >@arjan Your example is base on ManagedExecutorService from the Java EE
> Concurrency spec. That's one topic we've been wondering about : should the
> @Asynchronous interceptor go to the Java EE Concurrency spec or not ? But
> it looks like the spec might not be updated.
> >
> >
> >The example I showed here would IMHO best be placed in the Java EE
> Concurrency spec. That would in my opinion be a perfect analogy to
> @Transactional and JTA. As given, the interceptor uses CDI/Interceptors and
> Concurrency, so theoretically it could also be put into a third spec.
> >
> >
> >Personally I would find it strange to put something in spec A, when it
> may better belong in spec B, just because spec B is not updated. What's
> holding the update of Java EE Concurrency back? If most of the EG members
> would be of the opinion that an @Asynchronous interceptor belongs best in
> Java EE Concurrency, then we can just update that spec, right?
> >
> >
> >I know that MR releases can be quite fast and agile process wise, while
> still packing some punch. JTA 1.2 itself was just such an MR, and JASPIC
> 1.1 was too. I was somewhat involved with JASPIC 1.1 (as community member)
> and I think the setup time was pretty fast. Mid feb 2013 we created the
> JIRA issues, the MR draft was published early march 2013 and the release
> was with EE 7 end may 2013.
> >
> >
> >If it would just be about putting a few interceptors formally in Java EE
> Concurrency, then why not do such small update for it?
> >
> >
> >Kind regards,
> >Arjan
> >
> >
> >>
> >>Antonio
> >>
> >>
> >>On Sat, Jan 17, 2015 at 12:32 AM, arjan tijms <arjan.tijms at gmail.com>
> wrote:
> >>
> >>Hi,
> >>>
> >>>
> >>>
> >>>On Fri, Jan 16, 2015 at 10:41 PM, Jozef Hartinger <jharting at redhat.com>
> wrote:
> >>>
> >>>Hi Arjan,
> >>>>
> >>>>I did some changes recently in Weld interceptors and this usecase
> now works smoothly. The code is not part of a release yet. See this
> test for a simple implementation of an @Async interceptor (basically
> the same as your initial attempt). Note that the chain is repeatable
> but at the same time it is not reset after dispatch to a different
> thread so you no longer need the ThreadLocal nor any other
> workaround.
> >>>>
> >>>
> >>>
> >>>That's quite a coincidence, it's indeed rather similar ;)
> >>>
> >>>
> >>>I wonder how it now works though, as the InvocationContext "ctx" does
> not seem to be made aware that it's been dispatched to a different thread
> from within the code. Does it use an internal thread local to keep state or
> so?
> >>>
> >>>
> >>>I'll also try to see what this does on OWB. Do you think this is
> something that should work, or just something that Weld happens to support
> regardless of the spec?
> >>>
> >>>
> >>>Kind regards,
> >>>Arjan
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>>
> https://github.com/weld/core/blob/master/tests-arquillian/src/test/java/org/jboss/weld/tests/interceptors/thread/async/AsyncInterceptor.java
> >>>>
> >>>>Jozef
> >>>>
> >>>>
> >>>>
> >>>>On 01/16/2015 06:17 PM, arjan tijms wrote:
> >>>>
> >>>>Hi,
> >>>>>
> >>>>>
> I'm attempting to emulate EJB's @Asynchronous in CDI using interceptors.
> >>>>>
> >>>>>Originally I had defined my interceptor as follows;
> >>>>>
> >>>>>@Interceptor
> >>>>>@Asynchronous
> >>>>>@Priority(APPLICATION)
> >>>>>public class AsynchronousInterceptor implements Serializable {
> >>>>>
> >>>>> private static final long serialVersionUID = 1L;
> >>>>>
> >>>>> @Resource
> >>>>> private ManagedExecutorService managedExecutorService;
> >>>>>
> >>>>> @AroundInvoke
> >>>>> public Object submitAsync(InvocationContext ctx) throws
> Exception {
> >>>>> return new
> FutureDelegator(managedExecutorService.submit( ()-> {
> return ctx.proceed(); } ));
> >>>>> }
> >>>>>
> >>>>>}
> >>>>>
> >>>>>
> >>>>>With FutureDelegator as follows:
> >>>>>
> >>>>>public class FutureDelegator implements Future<Object> {
> >>>>>
> >>>>> private Future<?> future;
> >>>>>
> >>>>> public FutureDelegator(Future<?> future) {
> >>>>> this.future = future;
> >>>>> }
> >>>>>
> >>>>> @Override
> >>>>> public Object get() throws InterruptedException,
> ExecutionException {
> >>>>> AsyncResult<?> asyncResult =
> (AsyncResult<?>) future.get();
> >>>>> if (asyncResult == null) {
> >>>>> return null;
> >>>>> }
> >>>>>
> >>>>> return asyncResult.get();
> >>>>> }
> >>>>>
> >>>>> @Override
> >>>>> public Object get(long timeout, TimeUnit unit) throws
> InterruptedException, ExecutionException, TimeoutException
> {
> >>>>> AsyncResult<?> asyncResult =
> (AsyncResult<?>) future.get(timeout, unit);
> >>>>> if (asyncResult == null) {
> >>>>> return null;
> >>>>> }
> >>>>>
> >>>>> return asyncResult.get();
> >>>>> }
> >>>>>
> >>>>> @Override
> >>>>> public boolean cancel(boolean mayInterruptIfRunning) {
> >>>>> return future.cancel(mayInterruptIfRunning);
> >>>>> }
> >>>>>
> >>>>> @Override
> >>>>> public boolean isCancelled() {
> >>>>> return future.isCancelled();
> >>>>> }
> >>>>> @Override
> >>>>> public boolean isDone() {
> >>>>> return future.isDone();
> >>>>> }
> >>>>>
> >>>>>}
> >>>>>
> >>>>>
> >>>>>This of course didn't quite work, as the InvocationContext will be
> reset after the @AroundInvoke method returns, and an infinite intercept
> loop results (on Weld).
> >>>>>
> >>>>>I got it to work though on Weld by using a thread local check
> to break that loop:
> >>>>>
> >>>>>@Interceptor
> >>>>>@Asynchronous
> >>>>>@Priority(PLATFORM_BEFORE)
> >>>>>public class AsynchronousInterceptor implements Serializable {
> >>>>>
> >>>>> private static final long serialVersionUID = 1L;
> >>>>>
> >>>>> @Resource
> >>>>> private ManagedExecutorService managedExecutorService;
> >>>>>
> >>>>> private static final ThreadLocal<Boolean>
> asyncInvocation = new ThreadLocal<Boolean>();
> >>>>>
> >>>>> @AroundInvoke
> >>>>> public synchronized Object submitAsync(InvocationContext
> ctx) throws Exception {
> >>>>>
> >>>>> if (TRUE.equals(asyncInvocation.get())) {
> >>>>> return ctx.proceed();
> >>>>> }
> >>>>>
> >>>>> return new
> FutureDelegator(managedExecutorService.submit( ()-> {
> >>>>> try {
> >>>>> asyncInvocation.set(TRUE);
> >>>>> return ctx.proceed();
> >>>>> } finally {
> >>>>> asyncInvocation.remove();
> >>>>> }
> >>>>> }));
> >>>>> }
> >>>>>
> >>>>>}
> >>>>>
> >>>>>
> >>>>>But I've got a feeling this works just by chance and not because the
> workaround is so clever.
> >>>>>
> >>>>>
> >>>>>What do you guys think, what would be the best way to support this
> with the current CDI version? Or would CDI/Interceptors need something like
> Servlet's async support, where the InvocationContext is put into async mode
> whereafter it "simply" allows an other thread to continue processing on it?
> >>>>>
> >>>>>
> >>>>>Kind regards,
> >>>>>Arjan Tijms
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>_______________________________________________
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> >>>>
> >>>
> >>>_______________________________________________
> >>>cdi-dev mailing list
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> >>>https://lists.jboss.org/mailman/listinfo/cdi-dev
> >>>
> >>>Note that for all code provided on this list, the provider licenses the
> code under the Apache License, Version 2 (
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> provided on this list, the provider waives all patent and other
> intellectual property rights inherent in such information.
> >>>
> >>
> >>
> >>
> >>--
> >>
> >>Antonio Goncalves
> >>Software architect, Java Champion and Pluralsight author
> >>
> >>Web site | Twitter | LinkedIn | Pluralsight | Paris JUG | Devoxx France
> >
> >
> >
> >_______________________________________________
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> >cdi-dev at lists.jboss.org
> >https://lists.jboss.org/mailman/listinfo/cdi-dev
> >
> >Note that for all code provided on this list, the provider licenses the
> code under the Apache License, Version 2 (
> http://www.apache.org/licenses/LICENSE-2.0.html). For all other ideas
> provided on this list, the provider waives all patent and other
> intellectual property rights inherent in such information.
> >
> >
>
--
Antonio Goncalves
Software architect, Java Champion and Pluralsight author
Web site <http://www.antoniogoncalves.org> | Twitter
<http://twitter.com/agoncal> | LinkedIn <http://www.linkedin.com/in/agoncal> |
Pluralsight
<http://pluralsight.com/training/Authors/Details/antonio-goncalves> | Paris
JUG <http://www.parisjug.org> | Devoxx France <http://www.devoxx.fr>
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