[foreign-abi] RFR: 8248560: Specify the behaviour of the ForeignLinker returned by CSupport::getSystemLinker [v4]

[Jorn Vernee]

On Wed, 16 Sep 2020 11:51:38 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> src/jdk.incubator.foreign/share/classes/jdk/incubator/foreign/CLinker.java line 136:
>> 
>>> 134:      * the corresponding native stub will be deallocated.</p>
>>> 135:      *
>>> 136:      * <p>The method type of the target method handle is used for linking</p>
>> 
>> I think we can leave this out
>
> @PaulSandoz mentioned (and I agree) that the terms upcalls and downcalls are colloquial, in the sense that it's
> technically possible to pass an upcall stub to `downcallHandle`, so that it's no longer really making a downcall and,
> conversely, it's possible to pass a native method handle to `upcallStub` so that it will not, strictly speaking,
> execute an upcall to Java.  I think the real nature of what we're describing here is:
> * given an address and a function descriptor, obtain a MethodHandle which can be used to execute the code at that address
>   from Java code
> 
> * given a MethodHandle and a function descriptor, obtain a memory segment, whose base address can be passed to native
>   code where a function pointer is expected
> 
> I don't know if the terms downcallHandle and upcallStub are the best to describe what these do.

Maybe we can incorporate 'link' in the name? Since we're using CLinker as a name as well. Maybe we can call them:
`linkForeignFunction` or maybe `linkAddress` and `linkMethodHandle`?

-------------

PR: https://git.openjdk.java.net/panama-foreign/pull/327