checkNotNull(key);
      checkNotNull(loader);
      try {
        if (count != 0) { // read-volatile
          // don't call getLiveEntry, which would ignore loading values
          ReferenceEntry<K, V> e = getEntry(key, hash);
          if (e != null) {
            long now = map.ticker.read();
            V value = getLiveValue(e, now);