[foreign-abi] RFR: JDK-8243669: Improve library loading for Panama libraries

[Samuel Audet]

On 4/28/20 10:39 AM, Maurizio Cimadamore wrote:
> On 27/04/2020 23:13, Samuel Audet wrote:
>> If reference counting gets used for both memory allocations and library
>> loading, what about extracting that functionality into a public API that we
>> could use with any other resources out there, such as GPU resources?
>> JavaCPP is already doing that and it works great, but I don't see any
>> reason why this kind of feature shouldn't be part of the JDK, something
>> I've mentioned before...
> 
> There's no _explicit_ reference counting mechanism anywhere - not in the 
> memory segment API, not in the library lookup API (which is what changed 
> here). Not sure what you have in mind - but with the foreign API we have 
> been trying to stay clear of explicit 'retain'/'release' calls.  Is 
> there a specific reason why you think that the JDK would be in a unique 
> position to provide a better solution for something like this?

I understand that there is no "explicit reference counting", but it is 
nonetheless exactly what it is doing "under the hood". Let's put aside 
the question of offering a standard API for reference counting, and 
start with a simpler problem first. Since you wish to abstract away 
completely reference counting from users when it comes to memory 
allocations and library loading, what are you planning to do about its 
limitations, mainly when dealing with circular references?

Samuel