5621c414cf
## Summary One problem we have in the cache today is that we can't overwrite entries atomically, because we store unzipped _directories_ in the cache (which makes installation _much_ faster than storing zipped directories). So, if you ignore the existing contents of the cache when writing, you might run into an error, because you might attempt to write a directory where a directory already exists. This is especially annoying for cache refresh, because in order to refresh the cache, we have to purge it (i.e., delete a bunch of stuff), which is also highly unsafe if Puffin is running across multiple threads or multiple processes. The solution I'm proposing here is that whenever we persist a _directory_ to the cache, we persist it to a special "archive" bucket. Then, within the other buckets, directory entries are actually symlinks into that "archive" bucket. With symlinks, we can atomically replace, which means we can easily overwrite cache entries without having to delete from the cache. The main downside is that we'll now accumulate dangling entries in the "archive" bucket, and so we'll need to implement some form of garbage collection to ensure that we remove entries with no symlinks. Another downside is that cache reads and writes will be a bit slower, since we need to deal with creating and resolving these symlinks. As an example... after this change, the cache entry for this unzipped wheel is actually a symlink:  Then, within the archive directory, we actually have two unique entries (since I intentionally ran the command twice to ensure overwrites were safe):  |
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|---|---|---|
| .. | ||
| bench | ||
| cache-key | ||
| distribution-filename | ||
| distribution-types | ||
| gourgeist | ||
| install-wheel-rs | ||
| once-map | ||
| pep440-rs | ||
| pep508-rs | ||
| platform-host | ||
| platform-tags | ||
| puffin | ||
| puffin-build | ||
| puffin-cache | ||
| puffin-client | ||
| puffin-dev | ||
| puffin-dispatch | ||
| puffin-distribution | ||
| puffin-extract | ||
| puffin-fs | ||
| puffin-git | ||
| puffin-installer | ||
| puffin-interpreter | ||
| puffin-normalize | ||
| puffin-resolver | ||
| puffin-traits | ||
| puffin-warnings | ||
| puffin-workspace | ||
| pypi-types | ||
| requirements-txt | ||
| README.md | ||
README.md
Crates
bench
Functionality for benchmarking Puffin.
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.
gourgeist
A venv replacement to create virtual environments in Rust.
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.
puffin
Command-line interface for the Puffin package manager.
puffin-build
A PEP 517-compatible build frontend for Puffin.
puffin-cache
Functionality for caching Python packages and associated metadata.
puffin-client
Client for interacting with PyPI-compatible HTTP APIs.
puffin-dev
Development utilities for Puffin.
puffin-dispatch
A centralized struct for resolving and building source distributions in isolated environments.
Implements the traits defined in puffin-traits.
puffin-distribution
Client for interacting with built distributions (wheels) and source distributions (sdists). Capable of fetching metadata, distribution contents, etc.
puffin-extract
Utilities for extracting files from archives.
puffin-fs
Utilities for interacting with the filesystem.
puffin-git
Functionality for interacting with Git repositories.
puffin-installer
Functionality for installing Python packages into a virtual environment.
puffin-interpreter
Functionality for detecting and leveraging the current Python interpreter.
puffin-normalize
Normalize package and extra names as per Python specifications.
puffin-package
Types and functionality for working with Python packages, e.g., parsing wheel files.
puffin-resolver
Functionality for resolving Python packages and their dependencies.
puffin-traits
Shared traits for Puffin, to avoid circular dependencies.
pypi-types
General-purpose type definitions for types used in PyPI-compatible APIs.
puffin-warnings
User-facing warnings for Puffin.
requirements-txt
Functionality for parsing requirements.txt files.