Core Type Compilation Issues

[Peter Levart]

On 08/15/2018 05:49 PM, dalibor topic wrote:
>
>
> On 06.08.2018 20:21, mr rupplin wrote:
>> Three problems that I run into when running the 'make jdk' after 
>> minor work on the System.java class for JNI and custom JDK:
>>
>> java/lang/memory/GroupListener.java:111:
>>
>> Can we get explanations for each of these? 
>
> No.
>
> There is no java.lang.memory in OpenJDK. So it looks as if you are not 
> using OpenJDK, you're using something else.

Or Mr. Rupplin is adding class GroupListener to OpenJDK, thus creating 
new package java.lang.memory.

In that case I would suggest adding the class to some existent jdk 
internal package of java.base module below the jdk.internal. package 
hierarchy (java.lang. hierarchy is reserved). But as David Holmes 
already suggested, if this class depends on java.rmi classes, it may not 
be located in java.base module if it wants to access these classes 
directly from compiled code. OTOH it must be located in java.base module 
if it wants to be used from java.lang.System class (which I suspect Mr. 
Rupplin is doing from his message mentioning work on System.java class). 
It is possible to access java.rmi classes from java.base module using 
reflection though. Or better yet, using ServiceLoader mechanism.

So I would suggest Mr. Rupplin to:
- define a jdk internal service interface for the minimal functionality 
needed from java.rmi module in the java.base module.
- implement this interface by a concealed class in the java.rmi module 
and provide the service by adding "provides" directive to 
module-info.java of the java.rmi module
- declare that java.base module "uses" the service (in the 
module-info.java of the java.base module)
- code the logic in java.lang.System or helper class by loading the 
service using ServiceLoader API - the logic should be prepared to not 
find any such service since java.rmi module may not be present at runtime
- service interface and any additional utility classes such as 
GroupListener in java.base module should be put into existent (or new) 
jdk internal package(s) below the jdk.internal. package hierarchy.
- the package containintg the service interface should be exported to 
java.rmi module only that provides the implementation of the service

Hope this helps,

Regards, Peter