## Summary
At present, we have two separate phases within the installation pipeline
related to populating wheels into the cache. The first phase downloads
the distribution, and then builds any source distributions into wheels;
the second phase unzips all the built wheels into the cache.
This PR merges those two phases into one, such that we seamlessly
download, build, and unzip wheels in one pass. This is more efficient,
since we can start unzipping while we build. It also ensures that if the
install _fails_ partway through, we don't end up with a bunch of
downloaded wheels that we never had a chance to unzip. The code is also
much simpler.
The main downside is that the user-facing feedback isn't as granular,
since we only have one phase and one progress bar for what was
originally three distinct phases.
Closes https://github.com/astral-sh/puffin/issues/571.
## Test Plan
I ran the benchmark script on two separate requirements files, and saw a
7% and 31% speedup respectively:
```text
+ TARGET=./scripts/benchmarks/requirements.txt
+ hyperfine --runs 100 --warmup 10 --prepare 'virtualenv --clear .venv' './target/release/main pip-sync ./scripts/benchmarks/requirements.txt --no-cache' --prepare 'virtualenv --clear .venv' './target/release/puffin pip-sync ./scripts/benchmarks/requirements.txt --no-cache'
Benchmark 1: ./target/release/main pip-sync ./scripts/benchmarks/requirements.txt --no-cache
Time (mean ± σ): 269.4 ms ± 33.0 ms [User: 42.4 ms, System: 117.5 ms]
Range (min … max): 221.7 ms … 446.7 ms 100 runs
Benchmark 2: ./target/release/puffin pip-sync ./scripts/benchmarks/requirements.txt --no-cache
Time (mean ± σ): 250.6 ms ± 28.3 ms [User: 41.5 ms, System: 127.4 ms]
Range (min … max): 207.6 ms … 336.4 ms 100 runs
Summary
'./target/release/puffin pip-sync ./scripts/benchmarks/requirements.txt --no-cache' ran
1.07 ± 0.18 times faster than './target/release/main pip-sync ./scripts/benchmarks/requirements.txt --no-cache'
```
```text
+ TARGET=./scripts/benchmarks/requirements-large.txt
+ hyperfine --runs 100 --warmup 10 --prepare 'virtualenv --clear .venv' './target/release/main pip-sync ./scripts/benchmarks/requirements-large.txt --no-cache' --prepare 'virtualenv --clear .venv' './target/release/puffin pip-sync ./scripts/benchmarks/requirements-large.txt --no-cache'
Benchmark 1: ./target/release/main pip-sync ./scripts/benchmarks/requirements-large.txt --no-cache
Time (mean ± σ): 5.053 s ± 0.354 s [User: 1.413 s, System: 6.710 s]
Range (min … max): 4.584 s … 6.333 s 100 runs
Benchmark 2: ./target/release/puffin pip-sync ./scripts/benchmarks/requirements-large.txt --no-cache
Time (mean ± σ): 3.845 s ± 0.225 s [User: 1.364 s, System: 6.970 s]
Range (min … max): 3.482 s … 4.715 s 100 runs
Summary
'./target/release/puffin pip-sync ./scripts/benchmarks/requirements-large.txt --no-cache' ran
```
## 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 @ https://files.pythonhosted.org/packages/0d/cc/ff1904eb5eb4b455e442834dabf9427331ac0fa02853bf83db817a7dd53d/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",
...
}
}
}
```
We now write the `direct_url.json` when installing, and _skip_
installing if we find a package installed via the direct URL that the
user is requesting.
A lot of TODOs, especially around cleaning up the `Source` abstraction
and its relationship to `DirectUrl`. I'm gonna keep working on these
today, but this works and makes the requirements clear.
Closes#332.
Charlie Marsh