protected synchronized void delete() throws IOException {
   if (LogGlobal.isDebugEnabled()) {
     /* LOG.debug("deleting "+historyFile+" and "+confFile) */
     LOG.deleting_and(historyFile.toString(), confFile.toString()).debug();
   }
   state = HistoryInfoState.DELETED;
   doneDirFc.delete(doneDirFc.makeQualified(historyFile), false);
   doneDirFc.delete(doneDirFc.makeQualified(confFile), false);
 }