code: int numDocs() throws IOException
     {
        if (indexNames.size() == 0)
        {
           return volatileIndex.getNumDocuments();
        }
        else
        {
           CachingMultiIndexReader reader = getIndexReader();
           try
           {
              return reader.numDocs();
           }
           finally
           {
              reader.release();
           }
        }
     }
docs: Returns the number of documents in this index.
  
  @return the number of documents in this index.
  @throws IOException
  if an error occurs while reading from the index.