private void basicClose() {
    flushAll();
    synchronized (crf) {
      if (!crf.RAFClosed) {
        try {
          crf.channel.close();
        } catch (IOException ignore) {
        }
        try {
          crf.raf.close();
        } catch (IOException ignore) {
        }
        crf.RAFClosed = true;
        stats.decOpenOplogs();
      }
      closed = true;
    }

    deleteFiles();
  }
Close the files of a oplog but don't set any state. Used by unit tests
geode-core/src/main/java/org/apache/geode/internal/cache/OverflowOplog.java