RFR: 8347408: Create an internal method handle adapter for system calls with errno [v8]

[Maurizio Cimadamore]

On Thu, 8 May 2025 07:54:17 GMT, Per Minborg <pminborg at openjdk.org> wrote:

>> As we advance, converting older JDK code to use the relatively new FFM API requires system calls that can provide `errno` and the likes to explicitly allocate a MemorySegment to capture potential error states. This can lead to negative performance implications if not designed carefully and also introduces unnecessary code complexity.
>> 
>> Hence, this PR proposes adding a JDK internal method handle adapter that can be used to handle system calls with `errno`, `GetLastError`, and `WSAGetLastError`.
>> 
>> It relies on an efficient carrier-thread-local cache of memory regions to allide allocations.
>
> Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove class

src/java.base/share/classes/jdk/internal/foreign/CaptureStateUtil.java line 53:

> 51:     private static final BufferStack POOL = BufferStack.of(CAPTURE_LAYOUT);
> 52: 
> 53:     // Do not use a lambda in order to allow early use in the init sequence

This can be a local variable in the static initializer, right -- e.g. no need to expose it at class-level?

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

PR Review Comment: https://git.openjdk.org/jdk/pull/25043#discussion_r2079201294