Testing very long delta chains

[Yuya Nishihara]

On Tue, 22 Dec 2015 23:30:20 -0800, Gregory Szorc wrote:
> On Tue, Dec 22, 2015 at 9:41 PM, Matt Mackall <mpm at selenic.com> wrote:
> > Things we can do better:
> >
> > - add a C decompress helper
> > - that works on lists of buffers
> > - that calls zlib directly
> > - that uses threads
> > - that uses larger buffers
> > - that uses a faster zlib
> >
> > (For this last, the cloudflare fork of zlib has a faster CRC function that
> > seems to be worth about 20%)
> >
> 
> From C, this will not be fun because Windows.
> 
> Half serious question: what are your thoughts on writing this in Rust? We
> can write a Rust library that provides a C ABI which Python can interface
> with (either via a Python C extension or via ctypes/cffi). Rust should be
> supported on all the platforms we care about. For building/distribution, we
> can provide wheels for Windows and OS X so `pip install` "just works" [and
> doesn't require a working compiler]. That leaves Linux and other Unixen.
> Most distributions these days offer a Rust package or are in the process of
> offering one. For the laggards, I assume we'll still have the pure Python
> fallback.

I like Rust, but I don't think their libraries and packaging stuff are mature
enough. For example, we'll need a non-std crate for zlib and its dependency
would be managed by cargo with an explicit version. And, it would be headache
to translate this sort of dependencies to system packages (e.g. .deb or .rpm).

Also, 32bit MSVC ABI isn't stable yet?