Fix ImportError from vendored code

[grlee77]

closes #251 by avoiding imports from private CuPy code

The new files here are just subsets of files present in CuPy that are not part of its public API. Only a few functions use functionality from this _vendored folder.

The whole folder is mainly here in order to have a version of cupyx.scipy.signal.fftconvolve with a modified choose_conv_mode. We should eventually just update the convolution selection code in CuPy so that we can remove these files.

I think fftconvolve itself was not present at all in CuPy 9.x, but even in the current development branch, the convolution choice function is still restricted to 1D

[jakirkham]

Thanks Greg! 😄

Instead of vendoring what if we do a try...except... to handle importing with the relocation?

Agree in the medium term would be good to contribute upstream to avoid needing these internal bits.

[grlee77]

what if we do a try...except... to handle importing with the relocation?

Do you mean modifying _ndimage_filters.py and others to something like this?

try:
    import cupyx.scipy.ndimage

    if hasattr(cupyx.scipy.ndimage, '_filters'):
        # CuPy 11.x
        from cupyx.scipy.ndimage._filters import _get_correlate_kernel
    else:
        from cupyx.scipy.ndimage.filters import _get_correlate_kernel

except ImportError:

    import cupy

    from cucim.skimage._vendored import _ndimage_filters_core as _filters_core


    @cupy.memoize(for_each_device=True)
    def _get_correlate_kernel(mode, w_shape, int_type, offsets, cval):
        return _filters_core._generate_nd_kernel(
            'correlate',
            'W sum = (W)0;',
            'sum += cast<W>({value}) * wval;',
            'y = cast<Y>(sum);',
            mode, w_shape, int_type, offsets, cval, ctype='W')

That would let us potentially benefit from any upstream improvements or fixes to _get_correlate_kernel, but I don't think that outweighs the risk that the behavior may change in unexpected ways?

[jakirkham]

Alright let's go with this as-is, but let's work on upstreaming the rest of what is needed for 22.06. Could you please file an issue to track this?

[jakirkham]

@gpucibot merge