On Mon, 5 May 2025 17:13:02 GMT, Per Minborg <[email protected]> wrote:
>> As we advance, 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 adding a JDK internal method handle adapter that can
>> be used to handle system calls with `errno`, `GetLastError`, and
>> `WSAGetLastError`.
>>
>> It relies on an efficient carrier-thread-local cache of memory regions to
>> allide allocations.
>
> Per Minborg has updated the pull request incrementally with three additional
> commits since the last revision:
>
> - Fix empty line at the end of a third file
> - Fix empty line at the end of another file
> - Fix empty line at the end of a file
src/java.base/share/classes/jdk/internal/foreign/CaptureStateUtil.java line 103:
> 101: }
> 102: return returnType;
> 103: }
Suggestion:
static Class<?> returnType(MethodHandle target) {
// Implicit null check
final MethodType type = target.type();
final Class<?> returnType = type.returnType();
if (!(returnType.equals(int.class) ||
returnType.equals(long.class))) {
throw illegalArgDoesNot(target, "return an int or a long");
}
if (type.parameterCount() == 0 || type.parameterType(0) !=
MemorySegment.class) {
throw illegalArgDoesNot(target, "have a MemorySegment as the
first parameter");
}
return returnType;
}
If returnType uses a local variable, type also uses a local variable.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/25043#discussion_r2075081366
