message: Take read lock instead of write one.
diff: @@ -317,8 +317,8 @@ impl StateProvider for LmdbGlobalState {
  trie_keys.clone(),
  &self
  .digests_without_missing_descendants
  - .write()
  - .expect("digest cache write lock"),
  + .read()
  + .expect("digest cache read lock"),
  )?;
  if missing_descendants.is_empty() {
  // There were no missing descendants on `trie_keys`, let's add them *and all of
  