Add configuration documentation for the build backend and make it the
preview default.
The build backend should generally work with default configuration
unless you want specific features such as flat layout or module
renaming, there is only a dedicated configuration, but no concept or
guide page for the build backend. Once the build backend is stable, we
can update the guide documentation to explain that uv defaults to its
own build backend, but other build backends are also supported.
The uv build backend becomes the default in preview, giving it more
exposure from users and preparing it to make it the default proper. The
current documentation retains warnings that the build backend is in
preview.
To see current uses of `uv_build` on GitHub:
https://github.com/search?q=path%3A**%2Fpyproject.toml+uv_build%3E%3D0&type=code
---------
Co-authored-by: Zanie Blue <contact@zanie.dev>
uv itself is a large package with many dependencies and lots of
features. To build a package using the uv build backend, you shouldn't
have to download and install the entirety of uv. For platform where we
don't provide wheels, it should be possible and fast to compile the uv
build backend. To that end, we're introducing a python package that
contains a trimmed down version of uv that only contains the build
backend, with a minimal dependency tree in rust.
The `uv_build` package is publish from CI just like uv itself. It is
part of the workspace, but has much less dependencies for its own
binary. We're using cargo deny to enforce that the network stack is not
part of the dependencies. A new build profile ensure we're getting the
minimum possible binary size for a rust binary.
---------
Co-authored-by: Zanie Blue <contact@zanie.dev>
## Summary
I believe `zlib-rs` is now a better choice on ARM and x86, so I'm just
going to assume it's a better choice everywhere. It's much easier to
build (removes our CMake dependency), and in my benchmarking, it's
substantially faster on ARM and faster or ~exactly even on my x86
Windows machine.
We migrated to `zlib-rs` once before (#9184); however, I later reverted
it as I learned that they were only doing compile-time feature
detection, and so `zlib-rs` was meaningfully slower on x86. They now
perform runtime feature detection:
https://trifectatech.org/blog/zlib-rs-is-faster-than-c/.
To benchmark, I wrote a script to create a local Simple API-compliant
registry (see the commit history) for a single package. Then I ran the
`install-cold` benchmark against that registry to install NumPy.
On ARM:
```
❯ uv run resolver --uv-pip-path ../../zlib-ng --uv-pip-path ../../zlib-rs \
--benchmark install-cold \
req.txt --warmup 10 --min-runs 30
Benchmark 1: ../../zlib-ng (install-cold)
Time (mean ± σ): 165.7 ms ± 34.7 ms [User: 64.4 ms, System: 93.2 ms]
Range (min … max): 141.8 ms … 293.2 ms 30 runs
Benchmark 2: ../../zlib-rs (install-cold)
Time (mean ± σ): 150.9 ms ± 16.2 ms [User: 57.4 ms, System: 86.4 ms]
Range (min … max): 135.3 ms … 202.4 ms 30 runs
Summary
../../zlib-rs (install-cold) ran
1.10 ± 0.26 times faster than ../../zlib-ng (install-cold)
```
I benchmarked this about 100 times on my Windows machine and found it
difficult to conclude anything beyond "They're nearly the same". Here's
an example:
```
PS C:\Users\crmar\workspace\puffin> hyperfine --prepare "uv venv" "zlib-rs.exe pip sync ./scripts/benchmark/req.txt" "zlib-ng.exe pip sync ./scripts/benchmark/req.txt" "zlib-rs.exe pip sync ./scripts/benchmark/req.txt" "zlib-ng.exe pip sync ./scripts/benchmark/req.txt" --runs 10 --warmup 5
Benchmark 1: zlib-rs.exe pip sync ./scripts/benchmark/req.txt
Time (mean ± σ): 240.6 ms ± 10.8 ms [User: 6.1 ms, System: 92.2 ms]
Range (min … max): 229.4 ms … 267.9 ms 10 runs
Benchmark 2: zlib-ng.exe pip sync ./scripts/benchmark/req.txt
Time (mean ± σ): 241.3 ms ± 6.2 ms [User: 7.7 ms, System: 90.6 ms]
Range (min … max): 233.9 ms … 252.1 ms 10 runs
Benchmark 3: zlib-rs.exe pip sync ./scripts/benchmark/req.txt
Time (mean ± σ): 242.8 ms ± 7.7 ms [User: 6.2 ms, System: 23.4 ms]
Range (min … max): 236.1 ms … 262.8 ms 10 runs
Benchmark 4: zlib-ng.exe pip sync ./scripts/benchmark/req.txt
Time (mean ± σ): 245.9 ms ± 5.7 ms [User: 1.5 ms, System: 59.4 ms]
Range (min … max): 240.9 ms … 257.3 ms 10 runs
Summary
zlib-rs.exe pip sync ./scripts/benchmark/req.txt ran
1.00 ± 0.05 times faster than zlib-ng.exe pip sync ./scripts/benchmark/req.txt
1.01 ± 0.06 times faster than zlib-rs.exe pip sync ./scripts/benchmark/req.txt
1.02 ± 0.05 times faster than zlib-ng.exe pip sync ./scripts/benchmark/req.txt
```
Closes#11885.
