update lz4 to 1.9.3 and replace deprecated lz4 functions

jonwright commented 3 years ago

(Please excuse my uninvited comments - I am someone who uses this code)

Allowing people to select an LZ4 version at compile time would let them link to Intel's IPP patched versions more easily. This is a little faster for certain use cases on intel processors. We would need to be able to define the include + link arguments for setup.py to use another version rather than the one that is bundled.
There is a comment in the LZ4 sources saying not to use the fast variants any more, so get rid of this line https://github.com/kiyo-masui/bitshuffle/blob/6899f5db159469e92e7b3c776d2087345e4d5b77/src/bitshuffle.c#L23 The recommendation comes from your lz4.h:
```
Obsolete LZ4_decompress_fast variants (since v1.9.0) :
*  These functions used to be faster than LZ4_decompress_safe(),
*  but this is no longer the case. They are now slower.
```

Hopefully these comments are useful.

weninc commented 3 years ago

Yes I agree being able to select the LZ4 version on compile time is very useful. Maybe that's best as a separate PR?
Good catch. I replaced the deprecated lz4 functions LZ4_decompress_fast and LZ4_compress.

james-s-willis commented 3 years ago

Hey @weninc, thanks for these changes! Are you able to update your fork? Then I can merge this PR. Thanks.

weninc commented 3 years ago

Great thanks. I just updated my fork

kiyo-masui / bitshuffle