private RegionLocations locateRowInCache(TableCache tableCache, byte[] row, int replicaId) {
    RegionLocations locs = tableCache.regionLocationCache.findForRow(row, replicaId);
    if (locs == null) {
      recordCacheMiss();
    } else {
      recordCacheHit();
    }
    return locs;
  }
The asynchronous locator for regions other than meta.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncNonMetaRegionLocator.java