preliminary RFR: 8049365 - Update JDI and JDWP for modules

[Lois Foltan]

On 12/10/2015 3:03 AM, serguei.spitsyn at oracle.com wrote:
> Please, review this initial fix for the Jigsaw Bill milestone task:
> https://bugs.openjdk.java.net/browse/JDK-8049365
>
>
> Jdk webrev:
> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/jdk/8049365-Jigsaw-jdk.0/
>
> Hotspot webrev:
> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8049365-Jigsaw-hs.0/
>
>
> Summary:
>
>   It is expected that the JDI and JDWP update for modules will have 
> several iterations.
>   This is the initial one, and it introduces a very minimal functionality.
>   The main purpose of this preliminary review is to make sure the JDI 
> and JDWP update
>   for modules goes in a right direction and has nothing obviously wrong.
>
>   It does not include yet the API's for introspection of the 
> ModuleDescriptor, Configuration and Layer.
>   There are no convincing use cases for it yet.
>   It is still TBD to contact and get more feedback from the NetBeans 
> and Eclipse debuggers teams.
>   We also could give them our custom build to try.
>
> This fix temporarily adds a VM support for the JDI allModules() as a 
> JNI function GetAllModules().
>   Any feedback on the Hotspot webrev as to how to implement it better 
> is welcome.

Hi Serguei,

This is definitely a good start for updating JDK and JDWP for modules.  
I did have a chance to look over the hotspot changes.  I would really 
prefer not to introduce a new ModulesTable data structure 
(modules.c/hpp).  The goal of the JVM support for jigsaw was to have one 
stop shopping with ModuleEntryTable and PackageEntryTable.  Those data 
structures keep track and record the module definitions.  As a matter of 
fact, last week Harold completely removed JDK 9's current PackageInfo 
Hashtable in the jake repo in favor of using the new PackageEntryTable.  
I can help by enhancing ModuleEntryTable to provide methods that 
Modules::get_all_modules() could call.  Would you be okay with that?

Thanks,
Lois

>   The plan is (as suggested by Alan) to re-implement it on the JVMTI 
> level.
>
>   It is a part of another Jigsaw Bill milestone task:
> https://bugs.openjdk.java.net/browse/JDK-8049364
> Update JVM TI for modules
>
> Thanks,
> Serguei
>
>
>