RFR: 8357847: (ch) AsynchronousFileChannel implementations should support FFM Buffers [v5]

[Alan Bateman]

On Fri, 13 Jun 2025 15:30:19 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Acquire the scope of a direct buffer before it is used and release it after the task has finished with it, whether the task execution is immediate or pended.
>
> Brian Burkhalter has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:
> 
>  - 8357912: Changes pursuant to JDK-8358958
>  - Merge
>  - 8357912: Add reading to test of unsupported views
>  - 8357912: Add similar changes to SimpleAsynchronousFileChannelImpl
>  - 8357847: Use IOUtil.bufferAddress; broaden testing of Arena types
>  - 8357847: WindowsAsynchronousFileChannelImpl should support FFM Buffers

I checked the latest update and the src changes look okay. I'll do a second pass on Monday.

For the test, can you remove the `@Disabled` from the etc/MemorySegments.java as that should give us good coverage.

test/jdk/java/nio/channels/AsynchronousFileChannel/Basic.java line 566:

> 564: 
> 565:     // tests unsupported MemorySegment view buffers
> 566:     static void testViewsOfConfinedArenas(Path file) throws IOException {

MemorySegments.testAsyncFileChannelReadWrite will test this too.

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PR Comment: https://git.openjdk.org/jdk/pull/25531#issuecomment-2971049932
PR Review Comment: https://git.openjdk.org/jdk/pull/25531#discussion_r2145599250