private HRegionLocation getCachedLocation(HRegionLocation loc) {
    TableCache tableCache = cache.get(loc.getRegion().getTable());
    if (tableCache == null) {
      return null;
    }
    RegionLocations locs = tableCache.regionLocationCache.get(loc.getRegion().getStartKey());
    return locs != null ? locs.getRegionLocation(loc.getRegion().getReplicaId()) : null;
  }
The asynchronous locator for regions other than meta.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncNonMetaRegionLocator.java