RFR: 8317514: Ensure MemorySegment is initialized before touching NativeMemorySegmentImpl

[Jorn Vernee]

On Fri, 13 Oct 2023 15:37:00 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> This PR makes sure that `MemorySegment` is initialized *before* any of its subclasses.
> This is done by centralizing all the memory segment factories in a single implementation class (`SegmentFactories`).
> Doing so addresses a possible deadlock condition when using multiple threads.

Marked as reviewed by jvernee (Reviewer).

src/java.base/share/classes/java/lang/foreign/MemorySegment.java line 1289:

> 1287:      * A zero-length native segment modelling the {@code NULL} address.
> 1288:      */
> 1289:     MemorySegment NULL = MemorySegment.ofAddress(0L);

The old no-arg constructor can now be removed from NativeMemroySegmentImpl as well I believe.

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PR Review: https://git.openjdk.org/jdk/pull/16187#pullrequestreview-1676911705
PR Review Comment: https://git.openjdk.org/jdk/pull/16187#discussion_r1358523909