First, replace all usages in files in-place. I used my editor for this.
If someone wants to add a one-liner that'd be fun.
Then, update directory and file names:
```
# Run twice for nested directories
find . -type d -print0 | xargs -0 rename s/puffin/uv/g
find . -type d -print0 | xargs -0 rename s/puffin/uv/g
# Update files
find . -type f -print0 | xargs -0 rename s/puffin/uv/g
```
Then add all the files again
```
# Add all the files again
git add crates
git add python/uv
# This one needs a force-add
git add -f crates/uv-trampoline
```
Instead of dropping versions without a compatible distribution, we track
them as incompatibilities in the solver. This implementation follows
patterns established in https://github.com/astral-sh/puffin/pull/1290.
This required some significant refactoring of how we track incompatible
distributions. Notably:
- `Option<TagPriority>` is now `WheelCompatibility` which allows us to
track the reason a wheel is incompatible instead of just `None`.
- `Candidate` now has a `CandidateDist` with `Compatible` and
`Incompatibile` variants instead of just `ResolvableDist`; candidates
are not strictly compatible anymore
- `ResolvableDist` was renamed to `CompatibleDist`
- `IncompatibleWheel` was given an ordering implementation so we can
track the "most compatible" (but still incompatible) wheel. This allows
us to collapse the reason a version cannot be used to a single
incompatibility.
- The filtering in the `VersionMap` is retained, we still only store one
incompatible wheel per version. This is sufficient for error reporting.
- A `TagCompatibility` type was added for tracking which part of a wheel
tag is incompatible
- `Candidate::validate_python` moved to
`PythonRequirement::validate_dist`
I am doing more refactoring in #1298 — I think a couple passes will be
necessary to clarify the relationships of these types.
Includes improved error message snapshots for multiple incompatible
Python tag types from #1285 — we should add more scenarios for coverage
of behavior when multiple tags with different levels are present.
This rollbacks the optimization in the previous commit to be more
general. That is, instead of specializing the case of a range for a
singleton version, we make iteration over the distributions in a
`VersionMap` more explicitly lazy. Iteration now provides a `Version`
(like it did previously) and a _handle_ to a distribution that can be
turned into a `ResolvableDist`.
Doing things this way permits callers to iterate over the versions and
only materialize a distribution if they actually need one. In cases like
candidate selection, one can often rule out use of a distribution
through its version alone, and thus skip construction of that
distribution entirely.
That is, a `PrioritizedDistribution` for a specific version of a
package is not actually materialized in memory until a corresponding
`VersionMap::get` call is made for that version. Similarly, iteration
lazily materializes distributions as it moves through the map. It
specifically does not materialize everything first.
The main reason why this is effective is that an
`OwnedArchive<SimpleMetadata>` represents a zero-copy (other than
reading the source file) version of `SimpleMetadata` that is really just
a `Vec<u8>` internally. The problem with `VersionMap` construction
previously is that it had to eagerly materialize a `SimpleMetadata` in
memory before anything else, which defeats a large part of the purpose
of zero-copy deserialization. By making more of `VersionMap`
construction itself lazy, we permit doing some parts of resolution
without necessarily fully deserializing a `SimpleMetadata` into memory.
Indeed, with this commit, in the warm cached case, a `SimpleMetadata` is
itself never materialized fully in memory.
This does not completely and totally fully realize the benefits of
zero-copy deserialization. For example, we are likely still building
lots of distributions in memory that we don't actually need in some
cases. Perhaps in cases where no resolution exists, or when one needs to
iterate over large portions of the total versions published for a
package.
Moves yanked version filtering from `VersionMap::from_metadata` to the
resolver and tracks it as a PubGrub unavailable incompatibility so
yanked versions are reflected in error messages.
e.g. before
```
╰─▶ Because only albatross<=0.1.0 is available and you require albatross>0.1.0,
we can conclude that the requirements are unsatisfiable.
```
after
```
╰─▶ Because only the following versions of albatross are available:
albatross<=0.1.0
albatross==1.0.0
and albatross==1.0.0 is unusable because it was yanked, we can conclude that albatross>0.1.0 cannot be used.
And because you require albatross>0.1.0, we can conclude that the requirements are unsatisfiable.
```
In the process of making VersionMap construction lazy, I realized this
refactoring would be useful to me. It also simplifies a fair bit of case
analysis and does fewer BTreeMap lookups during construction. With that
said, this doesn't seem to matter for perf:
```
$ hyperfine -w10 --runs 50 \
"puffin-main pip compile --cache-dir ~/astral/tmp/cache-main ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null" \
"puffin-test pip compile --cache-dir ~/astral/tmp/cache-test ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null"
Benchmark 1: puffin-main pip compile --cache-dir ~/astral/tmp/cache-main ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null
Time (mean ± σ): 146.8 ms ± 4.1 ms [User: 350.1 ms, System: 314.2 ms]
Range (min … max): 140.7 ms … 158.0 ms 50 runs
Benchmark 2: puffin-test pip compile --cache-dir ~/astral/tmp/cache-test ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null
Time (mean ± σ): 146.8 ms ± 4.5 ms [User: 359.8 ms, System: 308.3 ms]
Range (min … max): 138.2 ms … 160.1 ms 50 runs
Summary
puffin-main pip compile --cache-dir ~/astral/tmp/cache-main ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null ran
1.00 ± 0.04 times faster than puffin-test pip compile --cache-dir ~/astral/tmp/cache-test ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null
```
But the simplification is still nice, and will decrease the delta
between what we have now and a lazy version map.
(Please review this PR commit by commit.)
This PR closes an initial loop on zero-copy deserialization. That
is, provides a way to get a `Archived<SimpleMetadata>` (spelled
`OwnedArchive<SimpleMetadata>` in the code) from a `CachedClient`. The
main benefit of zero-copy deserialization is that we can read bytes
from a file, cast those bytes to a structured representation without
cost, and then start using that type as any other Rust type. The
"catch" is that the structured representation is not the actual type
you started with, but the "archived" version of it.
In order to make all this work, we ended up needing to shave a rather
large yak: we had to re-implement HTTP cache semantics. Previously,
we were using the `http-cache-semantics` crate. While it does support
Serde, it doesn't support `rkyv`. Moreover, even simple support for
`rkyv` wouldn't be enough. What we actually want is for the HTTP cache
semantics to be implemented on the *archived* type so that we can
decide whether our cached response is stale or not without needing to
do a full deserialization into the unarchived type. This is why, in
this PR, you'll see `impl ArchivedCachePolicy { ... }` instead of
`impl CachePolicy { ... }`. (The `derive(rkyv::Archive)` macro
automatically introduces the `ArchivedCachePolicy` type into the
current namespace.)
Unfortunately, this PR does not fully realize the dream that is
zero-copy deserialization. Namely, while a `CachedClient` can now
provide an `OwnedArchive<SimpleMetadata>`, the rest of our code
doesn't really make use of it. Indeed, as soon as we go to build a
`VersionMap`, we eagerly convert our archived metadata into an owned
`SimpleMetadata` via deserialization (that *isn't* zero-copy). After
this change, a lot of the work now shifts to `rkyv` deserialization
and `VersionMap` construction. More precisely, the main thing we drop
here is `CachePolicy` deserialization (which is now truly zero-copy)
and the parsing of the MessagePack format for `SimpleMetadata`. But we
are still paying for deserialization. We're just paying for it in a
different place.
This PR does seem to bring a speed-up, but it is somewhat underwhelming.
My measurements have been pretty noisy, but I get a 1.1x speedup fairly
often:
```
$ hyperfine -w5 "puffin-main pip compile --cache-dir ~/astral/tmp/cache-main ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null" "puffin-test pip compile --cache-dir ~/astral/tmp/cache-test ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null" ; A kang
Benchmark 1: puffin-main pip compile --cache-dir ~/astral/tmp/cache-main ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null
Time (mean ± σ): 164.4 ms ± 18.8 ms [User: 427.1 ms, System: 348.6 ms]
Range (min … max): 131.1 ms … 190.5 ms 18 runs
Benchmark 2: puffin-test pip compile --cache-dir ~/astral/tmp/cache-test ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null
Time (mean ± σ): 148.3 ms ± 10.2 ms [User: 357.1 ms, System: 319.4 ms]
Range (min … max): 136.8 ms … 184.4 ms 19 runs
Summary
puffin-test pip compile --cache-dir ~/astral/tmp/cache-test ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null ran
1.11 ± 0.15 times faster than puffin-main pip compile --cache-dir ~/astral/tmp/cache-main ~/astral/tmp/reqs/home-assistant-reduced.in -o /dev/null
```
One downside is that this does increase cache size (`rkyv`'s
serialization format is not as compact as MessagePack). On disk size
increases by about 1.8x for our `simple-v0` cache.
```
$ sort-filesize cache-main
4.0K cache-main/CACHEDIR.TAG
4.0K cache-main/.gitignore
8.0K cache-main/interpreter-v0
8.7M cache-main/wheels-v0
18M cache-main/archive-v0
59M cache-main/simple-v0
109M cache-main/built-wheels-v0
193M cache-main
193M total
$ sort-filesize cache-test
4.0K cache-test/CACHEDIR.TAG
4.0K cache-test/.gitignore
8.0K cache-test/interpreter-v0
8.7M cache-test/wheels-v0
18M cache-test/archive-v0
107M cache-test/simple-v0
109M cache-test/built-wheels-v0
242M cache-test
242M total
```
Also, while I initially intended to do a simplistic implementation of
HTTP cache semantics, I found that everything was somewhat
inter-connected. I could have wrote code that _specifically_ only worked
with the present behavior of PyPI, but then it would need to be special
cased and everything else would need to continue to use
`http-cache-sematics`. By implementing what we need based on what Puffin
actually is (which is still less than what `http-cache-semantics` does),
we can avoid special casing and use zero-copy deserialization for our
cache policy in _all_ cases.
This PR adds initial support for [rkyv] to puffin. In particular,
the main aim here is to make puffin-client's `SimpleMetadata` type
possible to deserialize from a `&[u8]` without doing any copies. This
PR **stops short of actuallying doing that zero-copy deserialization**.
Instead, this PR is about adding the necessary trait impls to a variety
of types, along with a smattering of small refactorings to make rkyv
possible to use.
For those unfamiliar, rkyv works via the interplay of three traits:
`Archive`, `Serialize` and `Deserialize`. The usual flow of things is
this:
* Make a type `T` implement `Archive`, `Serialize` and `Deserialize`.
rkyv
helpfully provides `derive` macros to make this pretty painless in most
cases.
* The process of implementing `Archive` for `T` *usually* creates an
entirely
new distinct type within the same namespace. One can refer to this type
without naming it explicitly via `Archived<T>` (where `Archived` is a
clever
type alias defined by rkyv).
* Serialization happens from `T` to (conceptually) a `Vec<u8>`. The
serialization format is specifically designed to reflect the in-memory
layout
of `Archived<T>`. Notably, *not* `T`. But `Archived<T>`.
* One can then get an `Archived<T>` with no copying (albeit, we will
likely
need to incur some cost for validation) from the previously created
`&[u8]`.
This is quite literally [implemented as a pointer cast][rkyv-ptr-cast].
* The problem with an `Archived<T>` is that it isn't your `T`. It's
something
else. And while there is limited interoperability between a `T` and an
`Archived<T>`, the main issue is that the surrounding code generally
demands
a `T` and not an `Archived<T>`. **This is at the heart of the tension
for
introducing zero-copy deserialization, and this is mostly an intrinsic
problem to the technique and not an rkyv-specific issue.** For this
reason,
given an `Archived<T>`, one can get a `T` back via an explicit
deserialization step. This step is like any other kind of
deserialization,
although generally faster since no real "parsing" is required. But it
will
allocate and create all necessary objects.
This PR largely proceeds by deriving the three aforementioned traits
for `SimpleMetadata`. And, of course, all of its type dependencies. But
we stop there for now.
The main issue with carrying this work forward so that rkyv is actually
used to deserialize a `SimpleMetadata` is figuring out how to deal
with `DataWithCachePolicy` inside of the cached client. Ideally, this
type would itself have rkyv support, but adding it is difficult. The
main difficulty lay in the fact that its `CachePolicy` type is opaque,
not easily constructable and is internally the tip of the iceberg of
a rat's nest of types found in more crates such as `http`. While one
"dumb"-but-annoying approach would be to fork both of those crates
and add rkyv trait impls to all necessary types, it is my belief that
this is the wrong approach. What we'd *like* to do is not just use
rkyv to deserialize a `DataWithCachePolicy`, but we'd actually like to
get an `Archived<DataWithCachePolicy>` and make actual decisions used
the archived type directly. Doing that will require some work to make
`Archived<DataWithCachePolicy>` directly useful.
My suspicion is that, after doing the above, we may want to mush
forward with a similar approach for `SimpleMetadata`. That is, we want
`Archived<SimpleMetadata>` to be as useful as possible. But right
now, the structure of the code demands an eager conversion (and thus
deserialization) into a `SimpleMetadata` and then into a `VersionMap`.
Getting rid of that eagerness is, I think, the next step after dealing
with `DataWithCachePolicy` to unlock bigger wins here.
There are many commits in this PR, but most are tiny. I still encourage
review to happen commit-by-commit.
[rkyv]: https://rkyv.org/
[rkyv-ptr-cast]:
https://docs.rs/rkyv/latest/src/rkyv/util/mod.rs.html#63-68
Adds support for disabling installation from pre-built wheels i.e. the
package must be built from source locally.
We will still always use pre-built wheels for metadata during
resolution.
Available via `--no-binary` and `--no-binary-package <name>` flags in
`pip install` and `pip sync`. There is no flag for `pip compile` since
no installation happens there.
```
--no-binary
Don't install pre-built wheels.
When enabled, all installed packages will be installed from a source distribution.
The resolver will still use pre-built wheels for metadata.
--no-binary-package <NO_BINARY_PACKAGE>
Don't install pre-built wheels for a specific package.
When enabled, the specified packages will be installed from a source distribution.
The resolver will still use pre-built wheels for metadata.
```
When packages are already installed, the `--no-binary` flag will have no
affect without the `--reinstall` flag. In the future, I'd like to change
this by tracking if a local distribution is from a pre-built wheel or a
locally-built wheel. However, this is significantly more complex and
different than `pip`'s behavior so deferring for now.
For reference, `pip`'s flag works as follows:
```
--no-binary <format_control>
Do not use binary packages. Can be supplied multiple times, and each time adds to the
existing value. Accepts either ":all:" to disable all binary packages, ":none:" to empty the
set (notice the colons), or one or more package names with commas between them (no colons).
Note that some packages are tricky to compile and may fail to install when this option is
used on them.
```
Note we are not matching the exact `pip` interface here because it seems
complicated to use. I think we may want to consider adjusting our
interface for this behavior since we're not entirely compatible anyway
e.g. I think `--force-build` and `--force-build-package` are clearer
names. We could also consider matching the `pip` interface or only
allowing `--no-binary <package>` for compatibility. We can of course do
whatever we want in our _own_ install interfaces later.
Additionally, we may want to further consider the semantics of
`--no-binary`. For example, if I run `pip install pydantic --no-binary`
I expect _just_ Pydantic to be installed without binaries but by default
we will build all of Pydantic's dependencies too.
This work was prompted by #895, as it is much easier to measure
performance gains from building source distributions if we have a flag
to ensure we actually build source distributions. Additionally, this is
a flag I have used frequently in production to debug packages that ship
Cythonized wheels.
## Summary
`FlatIndex` is now the thing that's keyed on `PackageName`, while
`FlatDistributions` is what used to be called `FlatIndex` (a map from
version to `PrioritizedDistribution`, for a single package). I find this
a bit clearer, since we can also remove the `from_files` that doesn't
return `Self`, which I had trouble following.
## Summary
I'm running into some annoyances converting `&Version` to
`&PubGrubVersion` (which is just a wrapper type around `Version`), and I
realized... We don't even need `PubGrubVersion`?
The reason we "need" it today is due to the orphan trait rule: `Version`
is defined in `pep440_rs`, but we want to `impl
pubgrub::version::Version for Version` in the resolver crate.
Instead of introducing a new type here, which leads to a lot of
awkwardness around conversion and API isolation, what if we instead just
implement `pubgrub::version::Version` in `pep440_rs` via a feature? That
way, we can just use `Version` everywhere without any confusion and
conversion for the wrapper type.
Add directory `--find-links` support for local paths to pip-compile.
It seems that pip joins all sources and then picks the best package. We
explicitly give find links packages precedence if the same exists on an
index and locally by prefilling the `VersionMap`, otherwise they are
added as another index and the existing rules of precedence apply.
Internally, the feature is called _flat index_, which is more meaningful
than _find links_: We're not looking for links, we're picking up local
directories, and (TBD) support another index format that's just a flat
list of files instead of a nested index.
`RegistryBuiltDist` and `RegistrySourceDist` now use `WheelFilename` and
`SourceDistFilename` respectively. The `File` inside `RegistryBuiltDist`
and `RegistrySourceDist` gained the ability to represent both a url and
a path so that `--find-links` with a url and with a path works the same,
both being locked as `<package_name>@<version>` instead of
`<package_name> @ <url>`. (This is more of a detail, this PR in general
still work if we strip that and have directory find links represented as
`<package_name> @ file:///path/to/file.ext`)
`PrioritizedDistribution` and `FlatIndex` have been moved to locations
where we can use them in the upstack PR.
I added a `scripts/wheels` directory with stripped down wheels to use
for testing.
We're lacking tests for correct tag priority precedence with flat
indexes, i only confirmed this manually since it is not covered in the
pip-compile or pip-sync output.
Closes#876
Refactoring split out from find links support: Find links files can be
represented as `Dist`, but not really as `File`, they don't have url nor
hashes.
`DistRequiresPython` is somewhat odd as an in between type.
## Summary
This PR modifies the resolver to treat the Python version as a package,
which allows for better error messages (since we no longer treat
incompatible packages as if they "don't exist at all").
There are a few tricky pieces here...
First, we need to track both the interpreter's Python version and the
_target_ Python version, because we support resolving for other versions
via `--python 3.7`.
Second, we allow using incompatible wheels during resolution, as long as
there's a compatible source distribution. So we still need to test for
`requires-python` compatibility when selecting distributions.
This could use more testing, but it feels like an area where `packse`
would be more productive than writing PyPI tests.
Closes https://github.com/astral-sh/puffin/issues/406.
I've tried to investigate puffin's performance wrt to builds and
parallelism in general, but found the previous instrumentation to
granular. I've tried to add spans to every function that either needs
noticeable io or cpu resources without creating duplication. This also
fixes some wrong tracing usage on async functions
(https://docs.rs/tracing/latest/tracing/struct.Span.html#in-asynchronous-code)
and some spans that weren't actually entered.
## Summary
Now, `puffin_warnings::warn_once` and `puffin_warnings::warn` will go to
`stderr`, as long as the user isn't running under `--quiet`. Previously,
these went through `tracing`, and so were only visible when running
under `--verbose`.
## Summary
At present, when performing a `pip-install`, we first do a resolution,
then take the set of requirements and basically run them through our
`pip-sync`, which itself includes re-resolving the dependencies to get a
specific `Dist` for each package. (E.g., the set of requirements might
say `flask==3.0.0`, but the installer needs a specific _wheel_ or source
distribution to install.)
This PR removes this second resolution by exposing the set of pinned
packages from the resolution. The main challenge here is that we have an
optimization in the resolver such that we let the resolver read metadata
from an incompatible wheel as long as a source distribution exists for a
given package. This lets us avoid building source distributions in the
resolver under the assumption that we'll be able to install the package
later on, if needed. As such, the resolver now needs to track the
resolution and installation filenames separately.
Extends #517 with a suggestion from @konstin to parse the `SimpleJson`
into an intermediate type `SimpleMetadata(BTreeMap<Version,
VersionFiles>)` before converting to a `VersionMap`. This reduces the
number of times we need to parse the response. Additionally, we cache
the parsed response now instead of `SimpleJson`.
`VersionFiles` stores two vectors with
`WheelFilename`/`SourceDistFilename` and `File` tuples. These can be
iterated over together or separately. A new enum `DistFilename` was
added to capture the `SourceDistFilename` and `WheelFilename` variants
allowing iteration over both vectors.
I'm working off of @konstin's commit here to implement arbitrary unsat
test cases for the resolver.
The entirety of the resolver's io are two functions: Get the version map
for a package (PEP 440 version -> distribution) and get the metadata for
a distribution. A new trait `ResolverProvider` abstracts these two away and
allows replacing the real network requests e.g. with stored responses
(https://github.com/pradyunsg/pip-resolver-benchmarks/blob/main/scenarios/pyrax_198.json).
---------
Co-authored-by: konsti <konstin@mailbox.org>
## Summary
This enables users to rely on yanked versions via explicit `==` markers,
which is necessary in some projects (and, in my opinion, reasonable).
Closes#551.
## Summary
This PR modifies the behavior of our `--python-version` override in two
ways:
1. First, we always use the "real" interpreter in the source
distribution builder. I think this is correct. We don't need to use the
fake markers for recursive builds, because all we care about is the
top-level resolution, and we already assume that a single source
distribution will always return the same metadata regardless of its
build environment.
2. Second, we require that source distributions are compatible with
_both_ the "real" interpreter version and the marker environment. This
ensures that we don't try to build source distributions that are
compatible with our interpreter, but incompatible with the target
version.
Closes https://github.com/astral-sh/puffin/issues/407.
We're willing to use platform-incompatible wheels during resolution, to
quicken access to metadata... But we should avoid choosing an
incompatible wheel if the package lacks a source distribution since, in
that case, we definitely won't be able to install it.
Closes https://github.com/astral-sh/puffin/issues/439.
This works by filtering out files with a more recent upload time, so if
the index you use does not provide upload times, the results might be
inaccurate. pypi provides upload times for all files. This is, the field
is non-nullable in the warehouse schema, but the simple API PEP does not
know this field.
If you have only pypi dependencies, this means deterministic,
reproducible(!) resolution. We could try doing the same for git repos
but it doesn't seem worth the effort, i'd recommend pinning commits
since git histories are arbitrarily malleable and also if you care about
reproducibility and such you such not use git dependencies but a custom
index.
Timestamps are given either as RFC 3339 timestamps such as
`2006-12-02T02:07:43Z` or as UTC dates in the same format such as
`2006-12-02`. Dates are interpreted as including this day, i.e. until
midnight UTC that day. Date only is required to make this ergonomic and
midnight seems like an ergonomic choice.
In action for `pandas`:
```console
$ target/debug/puffin pip-compile --exclude-newer 2023-11-16 target/pandas.in
Resolved 6 packages in 679ms
# This file was autogenerated by Puffin v0.0.1 via the following command:
# target/debug/puffin pip-compile --exclude-newer 2023-11-16 target/pandas.in
numpy==1.26.2
# via pandas
pandas==2.1.3
python-dateutil==2.8.2
# via pandas
pytz==2023.3.post1
# via pandas
six==1.16.0
# via python-dateutil
tzdata==2023.3
# via pandas
$ target/debug/puffin pip-compile --exclude-newer 2022-11-16 target/pandas.in
Resolved 5 packages in 655ms
# This file was autogenerated by Puffin v0.0.1 via the following command:
# target/debug/puffin pip-compile --exclude-newer 2022-11-16 target/pandas.in
numpy==1.23.4
# via pandas
pandas==1.5.1
python-dateutil==2.8.2
# via pandas
pytz==2022.6
# via pandas
six==1.16.0
# via python-dateutil
$ target/debug/puffin pip-compile --exclude-newer 2021-11-16 target/pandas.in
Resolved 5 packages in 594ms
# This file was autogenerated by Puffin v0.0.1 via the following command:
# target/debug/puffin pip-compile --exclude-newer 2021-11-16 target/pandas.in
numpy==1.21.4
# via pandas
pandas==1.3.4
python-dateutil==2.8.2
# via pandas
pytz==2021.3
# via pandas
six==1.16.0
# via python-dateutil
```
[PEP 691](https://peps.python.org/pep-0691/#project-detail) has slightly
different, more relaxed rules around file metadata. These changes are
now reflected in the `File` struct. This will make it easier to support
alternative indices.
I had expected that i need to introduce a separate type for that, so i'm
happy it's two `Option`s more and an alias.
Part of #412
## Summary
This PR implements logic to sort wheels by priority, where priority is
defined as preferring more "specific" wheels over less "specific"
wheels. For example, in the case of Black, my machine now selects
`black-23.11.0-cp311-cp311-macosx_11_0_arm64.whl`, whereas sorting by
lowest priority instead gives me `black-23.11.0-py3-none-any.whl`.
As part of this change, I've also modified the resolver to fallback to
using incompatible wheels when determining package metadata, if no
compatible wheels are available.
The `VersionMap` was also moved out of `resolver.rs` and into its own
file with a wrapper type, for clarity.
Closes https://github.com/astral-sh/puffin/issues/380.
Closes https://github.com/astral-sh/puffin/issues/421.
