*/
  public synchronized MergePolicy.OneMerge getNextMerge() {
    if (pendingMerges.size() == 0) {
      return null;
    } else {
      // Advance the merge from pending to running
      MergePolicy.OneMerge merge = pendingMerges.removeFirst();
      runningMerges.add(merge);
      return merge;
    }
  }