public class KindergartenManager extends BaseManager {
  static final int SLEEP_PERIOD = 1000; // was 100
  static final int MAX_RETRIES = 100; // was 10
  TreeSet<KindergartenManager> otherChildren;
  /** Creates new Kindergarten manager */
  public KindergartenManager() {
    super();
    otherChildren = new TreeSet<KindergartenManager>();
    otherChildren.add(this);
  }

  @Override
  public void resolveConflict(Transaction me, Transaction other) {
    try {
        KindergartenManager otherManager =
            (KindergartenManager) other.getContentionManager();
        // first, check sharing records.
        if (otherChildren.contains(otherManager)) {
          otherChildren.remove(otherManager);
          other.abort();           // My turn! My turn!
          return;
        }
        else {    otherChildren.add(otherManager);   }
        me.abort(); // give up
        return;
    } catch (ClassCastException e) {
      other.abort(); // Oh, other not a Kindergartener. Kill it.
      return;
      }
  }}