pub fn build_cgroup_key_map(
baseline: &CtprofSnapshot,
candidate: &CtprofSnapshot,
flatten: &[Pattern],
) -> BTreeMap<String, String>Expand description
Build the post-flatten-path → final-tightened-key map for
GroupBy::Cgroup under auto-normalization. Walks the union
of paths from both snapshots’ threads and cgroup_stats so
that Layer 3 (tighten) sees every contributor to a given
Layer-2 skeleton group. Returns the map keyed by post-flatten
path; consumers (build_groups, flatten_cgroup_stats)
look up the final key for any path they see.