RFR: 8347408: Create an internal method handle adapter for system calls with errno [v3]

[Shaojin Wen]

On Mon, 5 May 2025 17:13:02 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 three additional commits since the last revision:
> 
>  - Fix empty line at the end of a third file
>  - Fix empty line at the end of another file
>  - Fix empty line at the end of a file

src/java.base/share/classes/jdk/internal/foreign/CaptureStateUtil.java line 74:

> 72:         // The Cartesian product : (int.class, long.class) x ("errno", ...)
> 73:         // Do not use Streams in order to enable "early" use in the init sequence.
> 74:         for (Class<?> c : List.of(int.class, long.class)) {

Suggestion:

        for (Class<?> c : new Class<?>[] {int.class, long.class}) {

Isn't this safer to use during early initialization?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25043#discussion_r2075003232