RFR(M): JDK-8141070 vm/services/management.cpp should be resilient to missing 'jdk.management' module

[David Holmes]

Hi Dmitry,

On 14/01/2016 4:45 AM, Dmitry Samersoff wrote:
> Everybody,
>
> Please, review the fix:
>
> http://cr.openjdk.java.net/~dsamersoff/JDK-8141070/webrev.01/
>
> The problem:
>
>    Code in management.cpp throw NoClassDefFound exception if any of
> requested classes is missing.
>
>   But, in upcoming modular JDK classes that not belong to
> java.lang.management (sun.management, com.sun.management etc) might not
> be present.

Is this because the management API's are actually split across the base 
module (java.lang.management) and the jdk.management module? If so that 
seem messy. If not then I'm not understanding the issue.

I would have hoped that the management initialization function in the VM 
could simply check for the management module being present and set a 
flag that can be checked by all the management entry points. Something 
that might even be better done at the Java level. ??

Cheers,
David

> Solution:
>
>   Refactor class resolving code to support two type of classes - REQUIRED
> (still throw NCDFE if the class is missing) and OPTIONAL (just return
> NULL).
>
>    I introduced a new parameter to highlight the fact that a class is an
> optional one on caller side rather than handle it silently inside
> management.cpp.
>
> -Dmitry
>