feature: Use `uv` for managing plugin virtual envs?

[edgarrmondragon]

Feature scope

CLI (options, error messages, logging, etc.)

Description

uv^1 is a tool created by the Astral team (of Ruff fame). It's a drop-in replacement for most of the functionality of both pip and virtualenv, but faster (10x-100x).

It's probably not a good idea to think of replacing pip and virtualenv with it this early, but it could initially be added behind a feature flag.

[edgarrmondragon]

cc @BTheunissen

[edgarrmondragon]

In particular uv pip install --link-mode=hardlink seems like an interesting option for boosting performance of plugin installation:

      --link-mode <LINK_MODE>
          The method to use when installing packages from the global cache
          
          [default: clone]

          Possible values:
          - clone:    Clone (i.e., copy-on-write) packages from the wheel into the site packages
          - copy:     Copy packages from the wheel into the site packages
          - hardlink: Hard link packages from the wheel into the site packages

[WillDaSilva]

@edgarrmondragon is the clone option only supported on particularly file systems? If so, which ones? What does it fall back to if copy-on-write is not possible, or does it just error instead? Is there a practical risk that the hardlinks break, e.g. if the cache is cleared?

[edgarrmondragon]

is the clone option only supported on particularly file systems? If so, which ones?

Here's a good summary^1 of OS/FS support:

OS	FS	Copy command	System call
Linux	Bcachefs	cp --reflink=always	ficlone
	Btrfs
	XFS
	OCFS2
	Ext4	Unsupported.
	OpenZFS
FreeBSD
	ZFS
Solaris	Oracle ZFS	cp -z	reflink
MacOS	APFS	cp -c	clonefile
	HFS+	Unsupported; non-CoW FS.
Windows	NTFS
	ReFSv2	Not included.	DUPLICATE_EXTENTS_TO_FILE

And they seem to be using reflink-copy^2, which has the following to say:

At the moment Linux, Android, OSX, iOS, and Windows are supported.

Note: On Windows, the integrity information features are only available on Windows Server editions starting from Windows Server 2012. Client versions of Windows do not support these features. More Information

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What does it fall back to if copy-on-write is not possible, or does it just error instead?

Currently it errors. reflink-copy does have a simple copy fallback^3 available and its being reviewed^4 in uv.

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Is there a practical risk that the hardlinks break, e.g. if the cache is cleared?

I've only done simple testing so AFAICT they should be pretty safe, i.e. each hardlink is a reference so the same file on disk, and deleting a copy only deletes a reference so deleting uv's cache doesn't affect installed wheels.

[edgarrmondragon]

https://github.com/astral-sh/uv/issues/313 might not be a deal-breaker if we keep uv optional and instruct users to update their pip_urls if they wanna use uv

UPDATE 2024-03-22: This will be fixed in the next uv release.