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. Tested and passed tiers 1-3. ------------- Commit messages: - Simplify and optimize return filters - Select the appropriate layout - Merge branch 'master' into errno-util - Bump copyright years and rename method - Merge branch 'master' into errno-util - Merge branch 'master' into errno-util - Add tests and improve docs - Clean up - Rename test - Reuse MHs - ... and 8 more: https://git.openjdk.org/jdk/compare/8c87ea2b...878a4096 Changes: https://git.openjdk.org/jdk/pull/22391/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22391&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8347408 Stats: 368 lines in 3 files changed: 367 ins; 0 del; 1 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
