Incompatible change to java.lang.instrument.Instrumentation

[Peter Levart]

Hi Sven,

On 06/16/2017 11:08 AM, Sven Reimers wrote:
> Hi Peter,
>
> nice idea. The only drawback is this requires JDK 9 for a build. What 
> I wanted to check is if I can compile the same unchanged source tree 
> with JDK 8 and 9...

Another trick that comes to my mind is to dynamically generate a 
java.lang.instrument.Instrumentation implementation using 
java.lang.reflect.Proxy and create an InvocationHandler as a substitute 
for NbInstrumentation rather than directly implementing the interface...

Regards, Peter

>
> Since there is not yet a hard requirement for JDK 9 compilation, i.e. 
> this is just an experiment to figure out things that may be broken and 
> need work, I would not see any actions on NetBeans side at the moment. 
> I was just astonished about the breaking change naively assuming that 
> default methods should be an easy fix.
>
> Thanks for the hint, waiting what Alan comes up with in the meantime 
> (probably more projects could be hit by the problem)
>
> @Alan: Shall I file a bug?
>
> Thanks for the fast responses
>
> Sven
>
> On Fri, Jun 16, 2017 at 10:21 AM, Peter Levart <peter.levart at gmail.com 
> <mailto:peter.levart at gmail.com>> wrote:
>
>     Hi Sven,
>
>     Just an idea...
>
>     What NetBeans could probably do is to create a special
>     sub-interface of java.lang.instrument.Instrumentation in its
>     bootstrap jar file (the jar passed to class-path) and make that
>     jar file MR jar with two versions of say
>     org.netbeans.core.Instrumentation interfaces extending
>     java.lang.instrument.Instrumentation. The one for pre-9 JDK would
>     have an empty body while the one for JDK 9 would override the
>     newly introduced abstract methods with default implementations.
>     NetBeans implementation classes would then implement
>     org.netbeans.core.Instrumentation instead of
>     java.lang.instrument.Instrumentation.
>
>     Regards, Peter
>
>
>     On 06/16/2017 09:40 AM, Jaroslav Tulach wrote:
>
>         On pátek 16. června 2017 8:17:51 CEST Sven Reimers wrote:
>
>             Hi Alan,
>
>             the code in question I am looking at is in
>
>               o.n.bootstrap/src/org/netbeans/NbInstrumentation.java
>
>             So this looks more like some basic stuff baked deep into
>             NetBeans core...
>
>             cc'Ing Jaroslav Tulach who wrote this - he should have
>             some more details..
>             else I will try to figure this out.
>
>             Thanks for looking into this
>
>             Sven
>
>
>             On Fri, Jun 16, 2017 at 8:11 AM, Alan Bateman
>             <Alan.Bateman at oracle.com <mailto:Alan.Bateman at oracle.com>>
>
>             wrote:
>
>                 On 16/06/2017 06:54, Sven Reimers wrote:
>
>                     Hi all,
>
>                     as part of the process of the code donation from
>                     Oracle to Apache for
>                     NetBeans I tried a compilation of the source code
>                     using idk 9-ea+173. The
>                     compilation fails due to an added method boolean
>                     isModifiableModule(Module)
>                     in java.lang.instrument.Instrumentation.
>
>                     Should the newly added method on the interface
>                     Instrumentation have a
>                     default implementation to make this change source
>                     code compatible from 8
>                     to
>                     9, e.g.
>
>                     default boolean isModifiableModule(Module module) {
>
>                           return false;
>
>                     }
>
>
>                     Is it already to late for changing this before JDK
>                     9 release?
>
>                     You are correct that adding abstract methods to
>                     Instrumentation is an
>
>                 incompatible change but the long term assumption in
>                 this area has always
>                 been it wouldn't be implemented outside of the
>                 java.instrument module.
>                 There were 4 abstract methods added to it in Java SE 6
>                 and I don't recall
>                 anyone screaming (pre-dates default methods of course).
>
>         Looks like I have implemented the code when compiling against
>         JDK7.
>
>                 So can you say what NetBeans is doing? Is this
>                 mocking, maybe
>                 forwarding/intercepting?
>
>         See https://netbeans.org/bugzilla/show_bug.cgi?id=237919
>         <https://netbeans.org/bugzilla/show_bug.cgi?id=237919>
>
>                 If there is a compelling reasons then we could
>                 try
>                 to see about changing redefineModule and the other new
>                 methods to be
>                 default methods but it is late and there is more to
>                 this that changing
>                 them
>                 to be default methods.
>
>         -jt
>
>
>
>
>
> -- 
> Sven Reimers
>
> * Senior Expert Software Architect
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