uv/crates/pep508-rs
Andrew Gallant 6c98ae9d77
pep440: rewrite the parser and make version comparisons cheaper (#789)
This PR builds on #780 by making both version parsing faster, and
perhaps more importantly, making version comparisons much faster.
Overall, these changes result in a considerable improvement for the
`boto3.in` workload. Here's the status quo:

```
$ time puffin pip-compile --no-build --cache-dir ~/astral/tmp/cache/ -o /dev/null ./scripts/requirements/boto3.in
Resolved 31 packages in 34.56s

real    34.579
user    34.004
sys     0.413
maxmem  2867 MB
faults  0
```

And now with this PR:

```
$ time puffin pip-compile --no-build --cache-dir ~/astral/tmp/cache/ -o /dev/null ./scripts/requirements/boto3.in
Resolved 31 packages in 9.20s

real    9.218
user    8.919
sys     0.165
maxmem  463 MB
faults  0
```

This particular workload gets stuck in pubgrub doing resolution, and
thus benefits mightily from a faster `Version::cmp` routine. With that
said, this change does also help a fair bit with "normal" runs:

```
$ hyperfine -w10 \
    "puffin-base pip-compile --cache-dir ~/astral/tmp/cache/ -o /dev/null ./scripts/benchmarks/requirements.in" \
    "puffin-cmparc pip-compile --cache-dir ~/astral/tmp/cache/ -o /dev/null ./scripts/benchmarks/requirements.in"
Benchmark 1: puffin-base pip-compile --cache-dir ~/astral/tmp/cache/ -o /dev/null ./scripts/benchmarks/requirements.in
  Time (mean ± σ):     337.5 ms ±   3.9 ms    [User: 310.5 ms, System: 73.2 ms]
  Range (min … max):   333.6 ms … 343.4 ms    10 runs

Benchmark 2: puffin-cmparc pip-compile --cache-dir ~/astral/tmp/cache/ -o /dev/null ./scripts/benchmarks/requirements.in
  Time (mean ± σ):     189.8 ms ±   3.0 ms    [User: 168.1 ms, System: 78.4 ms]
  Range (min … max):   185.0 ms … 196.2 ms    15 runs

Summary
  puffin-cmparc pip-compile --cache-dir ~/astral/tmp/cache/ -o /dev/null ./scripts/benchmarks/requirements.in ran
    1.78 ± 0.03 times faster than puffin-base pip-compile --cache-dir ~/astral/tmp/cache/ -o /dev/null ./scripts/benchmarks/requirements.in
```

There is perhaps some future work here (detailed in the commit
messages), but I suspect it would be more fruitful to explore ways of
making resolution itself and/or deserialization faster.

Fixes #373, Closes #396
2024-01-05 11:57:32 -05:00
..
src pep440: rewrite the parser and make version comparisons cheaper (#789) 2024-01-05 11:57:32 -05:00
Cargo.lock Copy over pep508-rs crate (#31) 2023-10-06 20:12:19 -04:00
Cargo.toml Update dependencies (#794) 2024-01-05 11:40:12 -05:00
License-Apache Copy over pep508-rs crate (#31) 2023-10-06 20:12:19 -04:00
License-BSD Copy over pep508-rs crate (#31) 2023-10-06 20:12:19 -04:00
Readme.md Copy over pep508-rs crate (#31) 2023-10-06 20:12:19 -04:00

Dependency specifiers (PEP 508) in Rust

Crates.io PyPI

A library for python dependency specifiers, better known as PEP 508.

Usage

In Rust

use std::str::FromStr;
use pep508_rs::Requirement;

let marker = r#"requests [security,tests] >= 2.8.1, == 2.8.* ; python_version > "3.8""#;
let dependency_specification = Requirement::from_str(marker).unwrap();
assert_eq!(dependency_specification.name, "requests");
assert_eq!(dependency_specification.extras, Some(vec!["security".to_string(), "tests".to_string()]));

In Python

from pep508_rs import Requirement

requests = Requirement(
    'requests [security,tests] >= 2.8.1, == 2.8.* ; python_version > "3.8"'
)
assert requests.name == "requests"
assert requests.extras == ["security", "tests"]
assert [str(i) for i in requests.version_or_url] == [">= 2.8.1", "== 2.8.*"]

Python bindings are built with maturin, but you can also use the normal pip install .

Version and VersionSpecifier from pep440_rs are reexported to avoid type mismatches.

Markers

Markers allow you to install dependencies only in specific environments (python version, operating system, architecture, etc.) or when a specific feature is activated. E.g. you can say importlib-metadata ; python_version < "3.8" or itsdangerous (>=1.1.0) ; extra == 'security'. Unfortunately, the marker grammar has some oversights (e.g. https://github.com/pypa/packaging.python.org/pull/1181) and the design of comparisons (PEP 440 comparisons with lexicographic fallback) leads to confusing outcomes. This implementation tries to carefully validate everything and emit warnings whenever bogus comparisons with unintended semantics are made.

In python, warnings are by default sent to the normal python logging infrastructure:

from pep508_rs import Requirement, MarkerEnvironment

env = MarkerEnvironment.current()
assert not Requirement("numpy; extra == 'science'").evaluate_markers(env, [])
assert Requirement("numpy; extra == 'science'").evaluate_markers(env, ["science"])
assert not Requirement(
    "numpy; extra == 'science' and extra == 'arrays'"
).evaluate_markers(env, ["science"])
assert Requirement(
    "numpy; extra == 'science' or extra == 'arrays'"
).evaluate_markers(env, ["science"])
from pep508_rs import Requirement, MarkerEnvironment

env = MarkerEnvironment.current()
Requirement("numpy; python_version >= '3.9.'").evaluate_markers(env, [])
# This will log: 
# "Expected PEP 440 version to compare with python_version, found '3.9.', "
# "evaluating to false: Version `3.9.` doesn't match PEP 440 rules"