Description
We try to avoid cloning a snapshot when the previous snapshot has not initialized, by awaiting on a detached context:
https://cs.opensource.google/go/x/tools/+/master:internal/lsp/cache/view.go;l=602;drc=929a8494cf60267d89035bc211b797a67b65a6b9
However, we also guard initialization with a sync.Once. As has been observed in #43554, it's possible to lose this race to awaitInitialized, such that we run initialization on the snapshot background context, which can be canceled.
As a result, we can clone a snapshot with incomplete metadata. This causes problems for any invalidation logic trying to preserve metadata, such as only invalidating metadata on go.mod saves. Additionally, this was difficult to debug: it would be nice to have a guarantee that we have a linear history of metadata in our snapshots.
After discussing, we think this is a relatively low priority since the current logic should only result in rare and transient breakages.
CC @stamblerre @heschik