RFR: 8347408: Create an internal method handle adapter for system calls with errno [v16]

[Maurizio Cimadamore]

On Thu, 16 Jan 2025 11:58:20 GMT, Per Minborg <pminborg at openjdk.org> wrote:

>> 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.explicitAllocationFail     avgt   30  41.615 ? 1.203  ns/op
>> CaptureStateUtilBench.explicitAllocationSuccess  avgt   30  23.094 ? 0.580  ns/op
>> CaptureStateUtilBench.threadLocalFail            avgt   30  14.760 ? 0.078  ns/op
>> CaptureStateUtilBench.threadLocalReuseSuccess    avgt   30   7.189 ? 0.151  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);
>> 
>> 
>> The graph below shows the difference in latency for a successful call:
>> 
>> ![image](https://github.com/user-attachments/assets/58fbef01-5d06-406c-87e6-75f468227fc6)
>> 
>> This is a ~3x improvement for both the happy and the error path.
>> 
>> 
>> Tested and passed tiers 1-3.
>
> Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove unused class

src/java.base/share/classes/jdk/internal/foreign/CaptureStateUtil.java line 289:

> 287: 
> 288: 
> 289:         private static final Supplier<MemorySegment> FACTORY = new Supplier<>() {

I think turning factory and recycler into abstract methods in the superclass might lead to cleaner code

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PR Review Comment: https://git.openjdk.org/jdk/pull/22391#discussion_r1918700262