[foreign-memaccess] [Rev 02] RFR: Alternative scalable MemoryScope

[Peter Levart]

> This is an alternative MemoryScope which is more scalable when used in a scenario where child scope is frequently
> acquired and closed concurrently from multiple threads (for example in parallel Stream.findAny())

Peter Levart has updated the pull request incrementally with one additional commit since the last revision:

  Re-add fullFence() in MemorySegment.withOwnerThread() due to effect on the segment backing memory which is not
  guaranteed by JMM otherwise

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

Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/142/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/142/files/04cb4f8c..3c68c958

Webrevs:
 - full: https://webrevs.openjdk.java.net/panama-foreign/142/webrev.02
 - incr: https://webrevs.openjdk.java.net/panama-foreign/142/webrev.01-02

  Stats: 6 lines in 1 file changed: 5 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/142.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/142/head:pull/142

PR: https://git.openjdk.java.net/panama-foreign/pull/142