## Summary
This PR adds a `VerbatimUrl` struct to preserve verbatim URLs throughout
the resolution and installation pipeline. In short, alongside the parsed
`Url`, we also keep the URL as written by the user. This enables us to
display the URL exactly as written by the user, rather than the
serialized path that we use internally.
This will be especially useful once we start expanding environment
variables since, at that point, we'll be able to write the version of
the URL that includes the _unexpected_ environment variable to the
output file.
This is mostly a mechanical refactor that moves 80% of our code to the
same cache abstraction.
It introduces cache `Cache`, which abstracts away the path of the cache
and the temp dir drop and is passed throughout the codebase. To get a
specific cache bucket, you need to requests your `CacheBucket` from
`Cache`. `CacheBucket` is the centralizes the names of all cache
buckets, moving them away from the string constants spread throughout
the crates.
Specifically for working with the `CachedClient`, there is a
`CacheEntry`. I'm not sure yet if that is a strict improvement over
`cache_dir: PathBuf, cache_file: String`, i may have to rotate that
later.
The interpreter cache moved into `interpreter-v0`.
We can use the `CacheBucket` page to document the cache structure in
each bucket:
## Summary and motivation
For a given source dist, we store the metadata of each wheel built
through it in `built-wheel-metadata-v0/pypi/<source dist
filename>/metadata.json`. During resolution, we check the cache status
of the source dist. If it is fresh, we check `metadata.json` for a
matching wheel. If there is one we use that metadata, if there isn't, we
build one. If the source is stale, we build a wheel and override
`metadata.json` with that single wheel. This PR thereby ties the local
built wheel metadata cache to the freshness of the remote source dist.
This functionality is available through `SourceDistCachedBuilder`.
`puffin_installer::Builder`, `puffin_installer::Downloader` and
`Fetcher` are removed, instead there are now `FetchAndBuild` which calls
into the also new `SourceDistCachedBuilder`. `FetchAndBuild` is the new
main high-level abstraction: It spawns parallel fetching/building, for
wheel metadata it calls into the registry client, for wheel files it
fetches them, for source dists it calls `SourceDistCachedBuilder`. It
handles locks around builds, and newly added also inter-process file
locking for git operations.
Fetching and building source distributions now happens in parallel in
`pip-sync`, i.e. we don't have to wait for the largest wheel to be
downloaded to start building source distributions.
In a follow-up PR, I'll also clear built wheels when they've become
stale.
Another effect is that in a fully cached resolution, we need neither zip
reading nor email parsing.
Closes#473
## Source dist cache structure
Entries by supported sources:
* `<build wheel metadata cache>/pypi/foo-1.0.0.zip/metadata.json`
* `<build wheel metadata
cache>/<sha256(index-url)>/foo-1.0.0.zip/metadata.json`
* `<build wheel metadata
cache>/url/<sha256(url)>/foo-1.0.0.zip/metadata.json`
But the url filename does not need to be a valid source dist filename
(<https://github.com/search?q=path%3A**%2Frequirements.txt+master.zip&type=code>),
so it could also be the following and we have to take any string as
filename:
* `<build wheel metadata
cache>/url/<sha256(url)>/master.zip/metadata.json`
Example:
```text
# git source dist
pydantic-extra-types @ git+https://github.com/pydantic/pydantic-extra-types.git
# pypi source dist
django_allauth==0.51.0
# url source dist
werkzeug @ ff1904eb5e/werkzeug-3.0.1.tar.gz
```
will be stored as
```text
built-wheel-metadata-v0
├── git
│ └── 5c56bc1c58c34c11
│ └── 843b753e9e8cb74e83cac55598719b39a4d5ef1f
│ └── metadata.json
├── pypi
│ └── django-allauth-0.51.0.tar.gz
│ └── metadata.json
└── url
└── 6781bd6440ae72c2
└── werkzeug-3.0.1.tar.gz
└── metadata.json
```
The inside of a `metadata.json`:
```json
{
"data": {
"django_allauth-0.51.0-py3-none-any.whl": {
"metadata-version": "2.1",
"name": "django-allauth",
"version": "0.51.0",
...
}
}
}
```
A consistent cache structure for remote wheel metadata:
* `<wheel metadata cache>/pypi/foo-1.0.0-py3-none-any.json`
* `<wheel metadata
cache>/<digest(index-url)>/foo-1.0.0-py3-none-any.json`
* `<wheel metadata cache>/url/<digest(url)>/foo-1.0.0-py3-none-any.json`
The source dist caching will use a similar structure (#468).
I intend this to become the main form of caching for puffin: You can
make http requests, you tranform the data to what you really need, you
have control over the cache key, and the cache is always json (or
anything else much faster we want to replace it with as long as it's
serde!)
