[Engine-devel] java 1.6 compatibility no more?

[Allon Mureinik]

----- Original Message -----
> From: "Juan Hernandez" <jhernand at redhat.com>
> To: "Allon Mureinik" <amureini at redhat.com>
> Cc: "Itamar Heim" <iheim at redhat.com>, engine-devel at ovirt.org
> Sent: Monday, July 23, 2012 1:22:37 PM
> Subject: Re: [Engine-devel] java 1.6 compatibility no more?
> 
> On 07/23/2012 11:46 AM, Allon Mureinik wrote:
> > 
> > 
> > ----- Original Message -----
> >> From: "Itamar Heim" <iheim at redhat.com>
> >> To: "Allon Mureinik" <amureini at redhat.com>
> >> Cc: "Livnat Peer" <lpeer at redhat.com>, "Juan Hernandez"
> >> <jhernand at redhat.com>, engine-devel at ovirt.org, "Michael
> >> Kublin" <mkublin at redhat.com>
> >> Sent: Monday, July 23, 2012 8:43:02 AM
> >> Subject: Re: [Engine-devel] java 1.6 compatibility no more?
> >>
> >> On 07/23/2012 08:29 AM, Allon Mureinik wrote:
> >>>
> >>>
> >>> ----- Original Message -----
> >>>> From: "Itamar Heim" <iheim at redhat.com>
> >>>> To: "Allon Mureinik" <amureini at redhat.com>
> >>>> Cc: "Livnat Peer" <lpeer at redhat.com>, "Juan Hernandez"
> >>>> <jhernand at redhat.com>, engine-devel at ovirt.org, "Michael
> >>>> Kublin" <mkublin at redhat.com>
> >>>> Sent: Sunday, July 22, 2012 7:41:00 PM
> >>>> Subject: Re: [Engine-devel] java 1.6 compatibility no more?
> >>>>
> >>>> On 07/22/2012 07:38 PM, Allon Mureinik wrote:
> >>>>>
> >>>>>
> >>>>> ----- Original Message -----
> >>>>>> From: "Livnat Peer" <lpeer at redhat.com>
> >>>>>> To: "Itamar Heim" <iheim at redhat.com>, "Michael Kublin"
> >>>>>> <mkublin at redhat.com>
> >>>>>> Cc: "Juan Hernandez" <jhernand at redhat.com>,
> >>>>>> engine-devel at ovirt.org
> >>>>>> Sent: Sunday, July 22, 2012 9:50:47 AM
> >>>>>> Subject: Re: [Engine-devel] java 1.6 compatibility no more?
> >>>>>>
> >>>>>> On 21/07/12 15:15, Itamar Heim wrote:
> >>>>>>> On 07/19/2012 03:34 PM, Ayal Baron wrote:
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> ----- Original Message -----
> >>>>>>>>>
> >>>>>>>>> On Jul 19, 2012, at 14:14 , Livnat Peer wrote:
> >>>>>>>>>
> >>>>>>>>>> On 19/07/12 14:41, Juan Hernandez wrote:
> >>>>>>>>>>> On 07/19/2012 01:39 PM, Yair Zaslavsky wrote:
> >>>>>>>>>>>> On 07/19/2012 02:31 PM, Vojtech Szocs wrote:
> >>>>>>>>>>>>>> Don't we need that (the source part) to avoid Java 7
> >>>>>>>>>>>>>> syntax
> >>>>>>>>>>>>>> in
> >>>>>>>>>>>>>> GWT code?
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> That's a very good point.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> In general, GWT compiler supports Java 5 syntax (note
> >>>>>>>>>>>>> that
> >>>>>>>>>>>>> there
> >>>>>>>>>>>>> are no language changes between Java 5 and 6). For this
> >>>>>>>>>>>>> reason,
> >>>>>>>>>>>>> our frontend code should be compliant with Java 5. If
> >>>>>>>>>>>>> someone
> >>>>>>>>>>>>> uses new Java 7 language features in frontend code, GWT
> >>>>>>>>>>>>> compiler will throw an error and the build will fail.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> So the 'Java 5 only' limitation applies to frontend
> >>>>>>>>>>>>> code
> >>>>>>>>>>>>> and
> >>>>>>>>>>>>> any
> >>>>>>>>>>>>> other code (e.g. shared modules) that is directly
> >>>>>>>>>>>>> referenced
> >>>>>>>>>>>>> by
> >>>>>>>>>>>>> frontend code. This shouldn't affect the backend,
> >>>>>>>>>>>>> however.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> We could do something like this:
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> - let oVirt root POM declare source and target
> >>>>>>>>>>>>> compliance
> >>>>>>>>>>>>> to
> >>>>>>>>>>>>> Java 7
> >>>>>>>>>>>>> - let frontend modules POM
> >>>>>>>>>>>>> (frontend/webadmin/modules/pom.xml)
> >>>>>>>>>>>>> declare source compliance to Java 5 (or 6)
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> (note that target compliance can be left to Java 7
> >>>>>>>>>>>>> since
> >>>>>>>>>>>>> frontend compilation results in JavaScript code)
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> What do you think?
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Vojtech
> >>>>>>>>>>>>
> >>>>>>>>>>>> +1 - I really like this idea!
> >>>>>>>>>>>
> >>>>>>>>>>> +1 from me as well.
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> There are two calls to make when it comes to JDK7
> >>>>>>>>>> (regardless
> >>>>>>>>>> of
> >>>>>>>>>> GWT -
> >>>>>>>>>> excuse me for taking this discussion some steps backwards)
> >>>>>>>>>>
> >>>>>>>>>> 1. Are we running with JRE 7?
> >>>>>>>>>> The answer is yes we agreed on that a few months ago.
> >>>>>>>>>>
> >>>>>>>>>> 2. Are we using code syntax which is incompatible with
> >>>>>>>>>> JDK6?
> >>>>>>>>>>
> >>>>>>>>>> I think the answer to the above should be no (at least for
> >>>>>>>>>> now
> >>>>>>>>>> -
> >>>>>>>>>> maybe
> >>>>>>>>>> until the next ovirt release?).
> >>>>>>>>> +1
> >>>>>>>>> exactly. Why starting with jdk6 incompatible constructs
> >>>>>>>>> unless
> >>>>>>>>> there
> >>>>>>>>> is a good (or at least any) reason for them…
> >>>>>>>>
> >>>>>>>> +1
> >>>>>>>
> >>>>>>> +1 - there is merit keeping backward compatibility to allow
> >>>>>>> comparing
> >>>>>>> behavior while java 7 is still young.
> >>>>>>
> >>>>>> Since no one objected, we'll go with JDK6 syntax compatibility
> >>>>>> for
> >>>>>> Now.
> >>>>> I'm a very small fan of enforcing policy by reviewers.
> >>>>> Not that the community reviews aren't great - but people miss
> >>>>> things.
> >>>>>
> >>>>> Here's my take on Maven's enforcer plugin to actually verify we
> >>>>> aren't compiling with JDK 7:
> >>>>> http://gerrit.ovirt.org/#/c/6523
> >>>>
> >>>> we don't want to enforce compilation or run with JDK 6, only to
> >>>> preserve
> >>>> backward compatibility.
> >>>> I'm for jenkins to have a job to compile and run unitests with
> >>>> openjdk 6
> >>>> to be on the safe side.
> >>>
> >>> I don't understand this suggestion.
> >>> What you're saying is that you can compile with whatever JDK you
> >>> want, but:
> >>> - it won't compile with JDKs prior to 6, since we're using 6's
> >>> features.
> >>> - you aren't allowed to use JDK 7 features, and if you do, you'll
> >>> get an email from jenkins that you broke something and must fix
> >>> it.
> >>>
> >>> To me, this sounds a lot like enforcing JDK 6 compatibility.
> >>>
> >>
> >> its preserving jdk 6 compatibility for a few more months, not
> >> enforcing
> >> to use jdk 6 compiler.
> > Fair enough.
> > 
> >>
> >>> /today/ if have way too many (i.e., >0) jenkins breaks, a lot of
> >>> which could be avoided by not running with -DskipTetst or making
> >>> sure to run with -Penable-dao-tests.
> >>> I fear this suggestion will just add to this "noise", and could
> >>> easily be avoided.
> >>
> >> jenkins breaks should be visible at patch level prior to commit,
> >> something we are trying to resolve by adding more hardware to
> >> allow
> >> running the various tests at patch level rather than post commit
> >> only.
> > I agree that this is an excellent goal, but I maintain that this is
> > an uncomfortable way to work.
> > I would still like a way to check, on my own machine, as part of my
> > compilation process, that I'm not doing anything I shouldn't.
> > Here's my second take on the issue, using Animal Sniffer
> > (http://mojo.codehaus.org/animal-sniffer/):
> > http://gerrit.ovirt.org/#/c/6540
> > 
> > Again, comments welcome.
> 
> Before going ahead I would check that using it doesn't increase the
> already long compilation time to an unacceptable level.
mvn clean install on my machine took just over 5 minutes - not too bad considering that up till a month ago or so it took 15-20 minutes to run the test suite.

> 
> Also need to make sure that the new dependency is available in the
> build
> environments we use. 
Built it against brew's repo, seemed to work fine.
If you have any more suggestions on how to check it, please advise.

> I am specially concerned about the Fedora build
> system, where we have the plugin but not the signatures for the JDKs.
The signatures are provided as part of the plugin - they are not taken directly from the JDK.
Or am I missing something in your point?

> This means that we will need to ignore the plugin or build the
> signatures ourselves.
Not so - see above.

> 
> Also take into account that every new maven plugin we add to the POMs
> introduces new potential problems with the maven eclipse support.
True.
IMHO, it's a small price to pay, but I guess that's why we discuss things upstream - to get different opinions ;-)

> 
> I think we can leave the decision to each developer, maybe providing
> an
> script that calls "mvn animal-sniffer:check ..." with the right
> parameters, maybe with git pre-commit hook, to make it more
> automatic.
I really don't like this approach, but again - difference of opinions :-)
Let's gather somemore feedback before deciding either way?

> This combined with the Jenkins checks can be a good compromise.
> 
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