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

[serguei.spitsyn at oracle.com]

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/


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