Function check_and_claim 

pub(crate) fn check_and_claim(
    fs: &FileStore,
    mstore: &Store,
    uid: &str,
    dir: &Path,
    cwd: &str,
    deadline: Instant,
) -> Result<Exclusivity, StoreError>

Decide whether dir — the memory directory uid’s spawn uses, from working directory cwd — is exclusive to uid, recording uid’s claim. Checks that can’t finish by deadline leave the directory Unproven, i.e. shared.