> Going forward, 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 to add a _JDK internal_ method handle adapter that
> can be used to handle system calls with `errno`, `GetLastError`, and
> `WSAGetLastError`.
>
> It currently relies on a thread-local cache of MemorySegments to allide
> allocations. If, in the future, a more efficient thread-associated allocation
> scheme becomes available, we could easily migrate to that one.
>
> Here are some benchmarks:
>
>
> Benchmark Mode Cnt Score Error Units
> CaptureStateUtilBench.explicitFail avgt 30 42.184 ? 0.998 ns/op
> CaptureStateUtilBench.explicitSuccess avgt 30 42.278 ? 1.490 ns/op
> CaptureStateUtilBench.tlFail avgt 30 23.594 ? 0.774 ns/op
> CaptureStateUtilBench.tlSuccess avgt 30 12.135 ? 0.107 ns/op
>
>
> Explicit allocation:
>
> try (var arena = Arena.ofConfined()) {
> return (int) HANDLE.invoke(arena.allocate(4), 0, 0);
> }
>
>
> Thread Local (tl):
>
> return (int) ADAPTED_HANDLE.invoke(arena.allocate(4), 0, 0);
>
>
> Tested and passed tiers 1-3.
Per Minborg has updated the pull request incrementally with two additional
commits since the last revision:
- Clean up benchmark
- Fix allocation problem in benchmark
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/22391/files
- new: https://git.openjdk.org/jdk/pull/22391/files/4821c2f2..f128c912
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=22391&range=05
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=22391&range=04-05
Stats: 11 lines in 1 file changed: 2 ins; 7 del; 2 mod
Patch: https://git.openjdk.org/jdk/pull/22391.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/22391/head:pull/22391
PR: https://git.openjdk.org/jdk/pull/22391
