Jigsaw Enhancement RFR round #3: 8159145 Add JVMTI function GetNamedModule

[serguei.spitsyn at oracle.com]

On 6/28/16 10:24, Daniel D. Daugherty wrote:
> On 6/27/16 10:20 PM, serguei.spitsyn at oracle.com wrote:
>> On 6/27/16 21:08, 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://cr.openjdk.java.net/~sspitsyn/webrevs/2016/hotspot/8159145-jigsaw-jvmti-pkg.3/ 
>>>
>>>
>>>
>>> The Jdk webrev is the same:
>>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2016/hotspot/8159145-jigsaw-jvmti-pkg.jdk1/ 
>>>
>>
>> Sorry, the Jdk webrev changed as well:
>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2016/hotspot/8159145-jigsaw-jvmti-pkg.jdk3/ 
>> '
>
> src/java.base/share/native/include/jvmti.h
>     No comments.
>
> Thumbs up on the 'jdk' repo change.

Thanks, Dan!
Serguei

>
> Dan
>
>
>
>
>>
>>
>> Thanks,
>> Serguei
>>
>>
>>>
>>>
>>> Summary:
>>>
>>>   This is the review round #3.
>>>   Alan suggested to replace the function GetModuleByPackageName with 
>>> the GetNamedModule.
>>> New function will return NULL if the package is not in a module 
>>> defined to the class loader.
>>>   It simplifies the API and makes it easier to specify.
>>> JVM TI agents that instrument code in named modules need the Module 
>>> at class load time.
>>>
>>>   One question that came from the function semantics change.
>>>   I had to implement the Modules::get_named_module() from scratch 
>>> independently of the existing
>>>   Modules::get_module_by_package_name() and Modules::get_module().
>>>   The issue is that the Modules::get_module() can return the unnamed 
>>> module whereas the
>>>   JVMTI helper Modules::get_named_module() should return NULL 
>>> instead of the unnamed module.
>>> Please, let me know if it is Ok or if you have better ideas how to 
>>> share the code.
>>>
>>>   This is the Summary from review round #1:
>>>
>>>   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.
>>>
>>>   It includes new jtreg test with native JVMTI agent.
>>>
>>>
>>> Testing:
>>>    Run newly developed jtreg test.
>>>
>>> Thanks,
>>> Serguei 
>>
>