@Override
  public void saveProperties(String mapKey, PropertyMap map) {
    synchronized(this) {
      store.saveProperties(mapKey, map);
      maps.put(mapKey, map);
    }
  }
A property map store using a pull-thru cache.
<p>
Before a map is returned, a check against the stored corresponding digest is performed to avoid
using stale data.
</p>
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/properties/CachingPropertyStore.java