class ActionView::Digestor

def digest(name:, finder:, dependencies: [])
  dependencies ||= []
  cache_key = ([ name ].compact + dependencies).join('.')
  # this is a correctly done double-checked locking idiom
  # (Concurrent::Map's lookups have volatile semantics)
  finder.digest_cache[cache_key] || @@digest_mutex.synchronize do
    finder.digest_cache.fetch(cache_key) do # re-check under lock
      partial = name.include?("/_")
      root = tree(name, finder, partial)
      dependencies.each do |injected_dep|
        root.children << Injected.new(injected_dep, nil, nil)
      end
      finder.digest_cache[cache_key] = root.digest(finder)
    end
  end
end