The 'HEAD' call that is done to resolve package revisions from
unpinned versions is already quite cheap, but it would still be better
to avoid overloading Github with such calls; especially for users of a
language-server that would compile on-the-fly very often. Upstream
packages don't change often so there's no need to constantly check the
etag.
So we now keep a local version of etags that we fetched, as well as a
timestamp from the last time we fetched them so that we only re-fetch
them if more than an hour has elapsed. This should be fairly resilient
while still massively improving the UX for people showing up after a
day and trying to use latest 'main' features.
This means that we now effectively have two caching levels:
- In the manifest, we store previously fetched etags.
- In the filesystem, we have a cache of already downloaded zip archives.
The first cache is basically invalidated every hour, while the second
cache is only invalidated when a etag changes. For pinned versions,
nothing is invalidated as they are considered immutable.
rvcas