Feature request: `purge()` many packages and their symlinks

[malcolmbarrett]

The global cache is great, but I often find myself wanting to start from scratch for one reason or another, particularly confirming reproducibility. purge() is limited in three main ways for this

• purge() only accepts one package at a time. I can get around this with lapply() + dependencies()
• Usually, when I want this approach, it is precisely this workflow: purge all packages in the cache that this project uses. Again, I can combine it with dependencies() to meet that need, but ideally this would be streamlined with a new argument like purge_project
• purge() does not remove symlinks. I think that could make sense as a default but I would like it if we could optionally remove the symlinks in the project, too. This would practically be limited to the project's symlinks and would still result in broken symlinks from any other project that used those packages from the cache.

Ideally, I would also be able to completely purge the entire cache (regardless of package and R version, project, etc) with something like purge_all.

Currently you can do this by just deleting the folder

# Retrieve the root cache path
cache_path <- renv::paths$root()

# Delete the entire cache directory recursively
unlink(cache_path, recursive = TRUE)   

but again, it would be nice to streamline this for reproducibility checks or other issues.

[kevinushey]

Thanks for the feature request! There's an internal function that might partially help here:

renv:::renv_cache_clean(prompt = TRUE)

This will identify and (with your confirmation) remove unused packages from the global cache. It works roughly as follows:

1. renv maintains a list of projects that have used the cache (stored in a projects file within the renv root).
2. For each project, it scans the project library and computes the expected cache path for each installed package (based on name, version, and a content hash of the DESCRIPTION).
3. It compares that set of "used" cache paths against everything actually present in the cache, and offers to remove the difference.

Fair warning: we're not 100% confident we're tracking package usage accurately across all projects — e.g. if a project has been moved or deleted, or its library is out of sync — so review the list before confirming.

For the other parts of your request (purging symlinks, purging many packages at once, purging the entire cache), those aren't yet exposed as user-facing API, but I'll keep the issue open for consideration.

[kevinushey]

The other thing worth considering -- you could also do something like

Sys.setenv(RENV_PATHS_CACHE = tempdir())

to use a unique / empty cache for your R session, to simulate the "empty" cache scenario without needing to touch the current cache state.

[malcolmbarrett]

thanks for the helpful suggestions!