Bug#1002056: ITP: zlib-ng -- optimized zlib compression library

[Guillem Jover <guillem@debian.org>]

On Mon, 2021-12-20 at 23:15:07 -0500, nick black wrote:
> not that i expect you to have run extensive benchmarks or
> anything, but how do you feel this compares to libdeflate?

I don't think it matters, because libdeflate does not support a
streaming API anyway, so it's of no use in many situations where
large files or streaming content needs to be dealt with. It also
does not provide a compatible zlib API, which means it cannot be
easily migrated to.

> the few comparisons i've seen suggest that they are (or at least
> were) pretty much a wash, performance-wise.

I think when I first noticed libdeflate being uploaded to Debian, I
took a look to also play with it for dpkg, but the above problems
meant that never got anywhere. From the benchmarks I've seen
libdeflate might be a bit faster, but then it would require tons more
memory to handle equivalent inputs and outputs.

The reasons I found the zlib-ng alternative interesting were because:

 - the Intel fork is not going to be adding non-Intel optimizations,
 - the Cloudflare fork does not look very lively,
 - the zlib upstream does not look very active, and apparently outright
   refuses contributions to the main code, and only accepts them into
   its contrib/ directory,

OTOH the zlib-ng looks very lively, accepts contributions, has had its
code modernized and cleaned up, and seems to be performing rather well
in comparison on multiple architectures.

Thanks,
Guillem