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class IndexModifier {
  /**
   * @see IndexModifier#setMergeFactor(int)
   * @throws CorruptIndexException if the index is corrupt
   * @throws LockObtainFailedException if another writer
   *  has this index open (<code>write.lock</code> could not
   *  be obtained)
   * @throws IOException if there is a low-level IO error
   */
  public int getMergeFactor() throws CorruptIndexException, LockObtainFailedException, IOException {
    synchronized(directory) {
      assureOpen();
      createIndexWriter();
      return indexWriter.getMergeFactor();
    }
  }

}