The change to have mypy's cache work is great (makes our

./pants check ::

runs 10x faster when there's a small change to python code), thank you! However, I noticed that there seems to be a single

cache.db

file per python verison in

~/.cache/pants/named_caches/mypy_cache/

. Does that mean a single cache is used for all invocations of mypy via pants? E.g. I've got multiple check-outs of our internal company repo (sharing a cache seems to make sense between them...), but also the pants repo, and sharing a cache between the pants and our internal one seems a bit unexpected?

cc @bitter-ability-32190

Yes! IIRC pants has a unique dir for these things per repo. @witty-crayon-22786 is that true of the append cache?

Yes! IIRC pants has a unique dir for these things per repo.

mm, we do not

No, specifically for mypy we do this

Ah, okay! That... doesn't seem to be functioning as I expect in 2.14, e.g.:

$ tree ~/.cache/pants/named_caches/mypy_cache/               
/Users/huon/.cache/pants/named_caches/mypy_cache/
├── 3.7
│   └── cache.db
├── 3.8
│   └── cache.db
└── 3.9
    └── cache.db

…ah. yea. the use of

append_only_caches

is wrong: https://github.com/pantsbuild/pants/blob/952235a048e8af742367867b5b7ca21243d020b6/src/python/pants/backend/python/typecheck/mypy/rules.py#L334

Oh yeah whoops. You win some you learn some 😅

append_only_caches

is definitely not the most obvious API

Lol. My heart was in the right place

we probably could do what you were suggesting above and differentiate

append_only_caches

from per-repo caches…

global_named_caches

and

repo_named_caches

…?

thank you!

I'll let you summarise anything frmo this discussion there.

Pex_root being an example of global? And mypy would be repo?