public Path getWALRegionDir() throws IOException {
    if (regionWalDir == null) {
      regionWalDir = CommonFSUtils.getWALRegionDir(conf, getRegionInfo().getTable(),
        getRegionInfo().getEncodedName());
    }
    return regionWalDir;
  }
@return the Region directory under WALRootDirectory
@throws IOException if there is an error getting WALRootDir
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java