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.
From PEP 517:
```python
def prepare_metadata_for_build_wheel(metadata_directory, config_settings=None):
...
```
> Must create a .dist-info directory containing wheel metadata inside
the specified metadata_directory (i.e., creates a directory like
{metadata_directory}/{package}-{version}.dist-info/).
```python
def build_wheel(wheel_directory, config_settings=None, metadata_directory=None):
...
```
> If the build frontend has previously called
prepare_metadata_for_build_wheel and depends on the wheel resulting from
this call to have metadata matching this earlier call, then it should
provide the path to the created .dist-info directory as the
metadata_directory argument.
Notice that the `metadata_directory` is different for the both hooks:
For `prepare_metadata_for_build_wheel` is doesn't contain the
`.dist-info` directory as final segment, for `build_wheel` it does.
Previously, the code assumed that both directories didn't contain the
`.dist-info` for both cases.
Checked with:
```
maturin build
uv init test-uv-build-backend --build-backend uv
cd test-uv-build-backend
uv build --sdist --preview
cd ..
UV_PREVIEW=1 pip install test-uv-build-backend/dist/test_uv_build_backend-0.1.0.tar.gz --no-index --find-links target/wheels/ -v --no-cache-dir
```
Fixes#9969
