[Engine-devel] java 1.6 compatibility no more?

[Itamar Heim]

On 07/23/2012 01:22 PM, Juan Hernandez wrote:
> 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.
>
> Also need to make sure that the new dependency is available in the build
> environments we use. I am specially concerned about the Fedora build
> system, where we have the plugin but not the signatures for the JDKs.
> This means that we will need to ignore the plugin or build the
> signatures ourselves.
>
> Also take into account that every new maven plugin we add to the POMs
> introduces new potential problems with the maven eclipse support.
>
> 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.
> This combined with the Jenkins checks can be a good compromise.
>

we really need the jenkins checks on patches... I'll try to push this 
some more.