## Summary This is a more robust fix for https://github.com/astral-sh/uv/issues/2300. The basic issue is: - When we resolve, we attempt to pre-fetch the distribution metadata for candidate packages. - It's possible that the resolution completes _without_ those pre-fetch responses. (In the linked issue, this was mainly because we were running with `--no-deps`, but the pre-fetch was causing us to attempt to build a package to get its dependencies. The resolution would then finish before the build completed.) - In that case, the `Index` will be marked as "waiting" for that response -- but it'll never come through. - If there's a subsequent call to the `Index`, to see if we should fetch or are waiting for that response, we'll end up waiting for it forever, since it _looks_ like it's in-flight (but isn't). (In the linked issue, we had to build the source distribution for the install phase of `pip install`, but `setuptools` was in this bad state from the _resolve_ phase.) This PR modifies the resolver to ensure that we flush the stream of requests before returning. Specifically, we now `join` rather than `select` between the resolution and request-handling futures. This _could_ be wasteful, since we don't _need_ those requests, but it at least ensures that every `.wait` is followed by ` .done`. In practice, I expect this not to have any significant effect on performance, since we end up using the pre-fetched distributions almost every time. ## Test Plan I ran through the test plan from https://github.com/astral-sh/uv/pull/2373, but ran the build 10 times and ensured it never crashed. (I reverted https://github.com/astral-sh/uv/pull/2373, since that _also_ fixes the issue in the proximate case, by never fetching `setuptools` during the resolve phase.) I also added logging to verify that requests are being handled _after_ the resolution completes, as expected. I also introduced an arbitrary error in `fetch` to ensure that the error was immediately propagated.
Crates
bench
Functionality for benchmarking uv.
cache-key
Generic functionality for caching paths, URLs, and other resources across platforms.
distribution-filename
Parse built distribution (wheel) and source distribution (sdist) filenames to extract structured metadata.
distribution-types
Abstractions for representing built distributions (wheels) and source distributions (sdists), and the sources from which they can be downloaded.
install-wheel-rs
Install built distributions (wheels) into a virtual environment.]
once-map
A waitmap-like concurrent hash map for executing tasks
exactly once.
pep440-rs
Utilities for interacting with Python version numbers and specifiers.
pep508-rs
Utilities for interacting with PEP 508 dependency specifiers.
platform-host
Functionality for detecting the current platform (operating system, architecture, etc.).
platform-tags
Functionality for parsing and inferring Python platform tags as per PEP 425.
uv
Command-line interface for the uv package manager.
uv-build
A PEP 517-compatible build frontend for uv.
uv-cache
Functionality for caching Python packages and associated metadata.
uv-client
Client for interacting with PyPI-compatible HTTP APIs.
uv-dev
Development utilities for uv.
uv-dispatch
A centralized struct for resolving and building source distributions in isolated environments.
Implements the traits defined in uv-traits.
uv-distribution
Client for interacting with built distributions (wheels) and source distributions (sdists). Capable of fetching metadata, distribution contents, etc.
uv-extract
Utilities for extracting files from archives.
uv-fs
Utilities for interacting with the filesystem.
uv-git
Functionality for interacting with Git repositories.
uv-installer
Functionality for installing Python packages into a virtual environment.
uv-interpreter
Functionality for detecting and leveraging the current Python interpreter.
uv-normalize
Normalize package and extra names as per Python specifications.
uv-package
Types and functionality for working with Python packages, e.g., parsing wheel files.
uv-resolver
Functionality for resolving Python packages and their dependencies.
uv-traits
Shared traits for uv, to avoid circular dependencies.
pypi-types
General-purpose type definitions for types used in PyPI-compatible APIs.
uv-virtualenv
A venv replacement to create virtual environments in Rust.
uv-warnings
User-facing warnings for uv.
requirements-txt
Functionality for parsing requirements.txt files.