[issue39298] add BLAKE3 to hashlib

[Jack O'Connor]

Jack O'Connor <oconnor663 at gmail.com> added the comment:

Hey Christian, yes these are new bindings, and also incomplete. See comments in https://github.com/oconnor663/cpython/commit/dc6f6163ad9754c9ad53e9e3f3613ca3891a77ba, but in short only x86-64 Unix is in working order. If 3.10 doesn't seem realistic, I'm happy to go the PyPI route. That said, this is my first time using the Python C API. (My code in that branch is going to make that pretty obvious.) Could you recommend any existing packages that I might be able to use as a model?

For OpenSSL, I'm very interested in the abstract but less familiar with their project and their schedules. Who might be a good person to get in touch with?

> I assume there's a completely generic platform-agnostic C implementation, for build environments where the assembly won't work, yes?

Yes, that's the vendored file blake3_portable.c. One TODO for my branch here is convincing the Python build system not to try to compile the x86-64-specific stuff on other platforms. The vendored file blake3_dispatch.c abstracts over all the different implementations and takes care of #ifdef'ing platform-specific function calls. (It also does runtime CPU feature detection on x86.)

> written using the Rust implementation, which I understand is even more performant

A few details here: The upstream Rust and C implementations have been matched in single threaded performance for a while now. They share the same assembly files, and the rest is a direct port. The big difference is that Rust also includes multithreading support, using the Rayon work-stealing runtime. The blake3-py module based on the Rust crate exposes this with a simple boolean flag, though we've been thinking about ways to give the caller more control over the number of threads used.

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<https://bugs.python.org/issue39298>
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