## Summary
This PR is an alternative approach to #949 which should be much safer.
As in #949, we add a `Refresh` policy to the cache. However, instead of
deleting entries from the cache the first time we read them, we now
check if the entry is sufficiently new (created after the start of the
command) if the refresh policy applies. If the entry is stale, then we
avoid reading it and continue onward, relying on the cache to
appropriately overwrite based on "new" data. (This relies on the
preceding PRs, which ensure the cache is append-only, and ensure that we
can atomically overwrite.)
Unfortunately, there are just a lot of paths through the cache, and
didn't data is handled with different policies, so I really had to go
through and consider the "right" behavior for each case. For example,
the HTTP requests can use `max-age=0, must-revalidate`. But for the
routes that are based on filesystem modification, we need to do
something slightly different.
Closes#945.
## 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):
We lock git checkout directories and the virtualenv to avoid two puffin
instances running in parallel changing files at the same time and
leading to a broken state. When one instance is blocking another, we
need to inform the user (why is the program hanging?) and also add some
information for them to debug the situation.
The new messages will print
```
Waiting to acquire lock for /home/konsti/projects/puffin/.venv (lockfile: /home/konsti/projects/puffin/.venv/.lock)
```
or
```
Waiting to acquire lock for git+https://github.com/pydantic/pydantic-extra-types@0ce9f207a1e09a862287ab77512f0060c1625223 (lockfile: /home/konsti/projects/puffin/cache-all-kinds/git-v0/locks/f157fd329a506a34)
```
The messages aren't perfect but clear enough to see what the contention
is and in the worst case to delete the lockfile.
Fixes#714
## Summary
This PR enables `puffin clean` to accept package names as command line
arguments, and selectively purge entries from the cache tied to the
given package.
Relate to #572.
## Test Plan
Modified all the caching tests to run an additional step to (1) purge
the cache, and (2) re-install the package.
## Summary
When installing a local wheel, we need to avoid removing the zipped
wheel (since it lives outside of the cache), _and_ need to ensure that
we unzip the wheel into the cache (rather than replacing the zipped
wheel, which may even live outside of the project).
Closes https://github.com/astral-sh/puffin/issues/553.
This PR modifies the source distribution building to replace any
existing targets after building the new wheel. In some cases, the
existence of an existing target may be indicative of a bug, so we warn.
It's partially a workaround for some (but not all) of the errors in
https://github.com/astral-sh/puffin/issues/554.
Charlie Marsh
konsti