Jigsaw Enhancement RFR round #2: 8159145 Add JVMTI function GetModuleByPackageName

[serguei.spitsyn at oracle.com]

Hi Stanislav,

Thank you for looking at this update and the comments!

On 6/22/16 10:09, stanislav lukyanov wrote:
> Hi Serguei,
>
> What is the expected behavior when passed string is not a valid 
> package name (e.g. contains illegal characters)?
> I think I'd expect JVMTI_ERROR_ILLEGAL_ARGUMENT to be returned in that 
> case.

I initially was thinking the same but currently have a doubt it is 
really needed.
Let's find out if we can reach a consensus here.


>
> Now it looks like the method will return unnamed module not only for 
> an empty string
> but for any string that is not a known package name.

Yes, this is correct.
We are not able to recognize non-existing package names and always 
return the unnamed package.
I'm still not sure we want to explicitly specify it.


> If it's correct, I think the empty string case shouldn't be described 
> explicitly.

I agree, it can confuse the users.
I still prefer to explicitly specify it.
The question is if we want to explicitly specify that we always return 
the unnamed package for non-existing packages.

Thanks,
Serguei


>
> Thanks,
> Stas
>
> On 22.06.2016 16:05, serguei.spitsyn at oracle.com wrote:
>> I've updated the libGetModuleByPkgTest.c in place in the webrev #2 
>> with minor improvements.
>> Sorry, if it spoiled your work.
>>
>> Thanks,
>> Serguei
>>
>>
>> On 6/22/16 04:07, serguei.spitsyn at oracle.com wrote:
>>> Here are new hotspot webrev where I've fixed the comments from Alan 
>>> and Christian.
>>>
>>> Hotspot:
>>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2016/hotspot/8159145-jigsaw-jvmti-pkg.2 
>>>
>>>
>>>
>>> The Jdk webrev is the same:
>>> http://javaweb.sfbay.sun.com/java/svc/ss45998/webrevs/2016/hotspot/8159145-jigsaw-jvmti-pkg.jdk1/ 
>>>
>>>
>>>
>>> Thanks,
>>> Serguei
>>>
>>>
>>> On 6/21/16 02:54, serguei.spitsyn at oracle.com wrote:
>>>>
>>>> Please, review the Jigsaw fix for the enhancement:
>>>> https://bugs.openjdk.java.net/browse/JDK-8159145
>>>>
>>>>
>>>> The Hotspot webrev:
>>>> http://javaweb.sfbay.sun.com/java/svc/ss45998/webrevs/2016/hotspot/8159145-jigsaw-jvmti-pkg.1/ 
>>>>
>>>>
>>>> The Jdk webrev:
>>>> http://javaweb.sfbay.sun.com/java/svc/ss45998/webrevs/2016/hotspot/8159145-jigsaw-jvmti-pkg.jdk1/ 
>>>>
>>>>
>>>>
>>>> Summary:
>>>>
>>>> JVM TI agents that instrument code in named modules need the Module 
>>>> at class load time.
>>>>
>>>>   One way to do this is by introducing a new ClassFileLoadHook that 
>>>> takes an additional parameter but this approach is disruptive.
>>>>   The alternative option is a JVM TI function that maps a 
>>>> classloader + package name to a module.
>>>>   We were initially not confident with this approach so we 
>>>> introduced it as JVM function JVM_GetModuleByPackageName.
>>>>   Based on experience to date then this approach seems okay and so 
>>>> this function needs to be promoted to a JVMTI function.
>>>>
>>>>   This fix is to introduce new JVMTI function GetModuleByPackageName.
>>>>   It includes new jtreg test with native JVMTI agent.
>>>>
>>>>   A CCC is fast-tracked and getting an approval is in progress.
>>>>
>>>> Testing:
>>>>    Run newly developed jtreg test.
>>>>
>>>> Thanks,
>>>> Serguei
>>>
>>
>