[foreign-memaccess+abi] RFR: 8263018: Improve API for lifecycle of native resources [v10]

[Maurizio Cimadamore]

On Fri, 12 Mar 2021 00:48:39 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

>> Maurizio Cimadamore has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Remove spurious println
>>  - Clarify javadoc for SegmentAllocator::arenaUnbounded
>
> src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/ArenaAllocator.java line 9:
> 
>> 7: import java.util.OptionalLong;
>> 8: 
>> 9: public class ArenaAllocator implements SegmentAllocator {
> 
> The implementations are not thread safe. Do we need to adjust the specification on SegmentAllocator accordingly?

I believe here there is some effort towards making everything thread-safe - in the sense that, based on the scope provided by the client (confined or shared) a different kind of allocator impl will be returned to the user. A shared bounded arena has a synchronized allocation method - while a shared unbound segment uses multiple underlying thread-local allocators.

Perhaps you refer to the fact that we don't check (in confined cases) that we are in the same thread as the scope's thread _before_ responding to an allocation request?

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PR: https://git.openjdk.java.net/panama-foreign/pull/466