Arena.addCloseAction and the implementation of a custom allocator

[Quân Anh Mai]

Hi,

I noticed that the method Arena::addCloseAction has been dropped from the
API. May I ask in that case what is the way to create a custom allocator
that manages its allocated memory? With the method, I believe it can be
achieved with something like this:

public MemorySegment allocate(long byteSize, long byteAlignment) {
    if (byteAlignment > MAX_ALIGNMENT) {
        throw new IllegalArgumentException();
    }

    try {
        var arena = Arena.ofAuto();
        long address = (long)MALLOC.invokeExact(byteSize); // I assume this
should work since other reinterpret casts like unsigned <-> int is legal
here
        arena.addCloseAction(() -> {
                try {
                    FREE.invokeExact(address);
                } catch(Throwable e) {
                    throw new RuntimeException(e);
                }
        });
        return MemorySegment.ofAddress(address, byteSize, arena);
    } catch(Throwable e) {
        throw new RuntimeException(e);
    }
}

Thanks a lot,
Quan Anh
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