@Override
 public Map<String, Double> getActiveSegmentCompressionRatios() {
   Map<String, Double> segmentRatios = new TreeMap<>();
   for (CommitLogSegment segment : allocator.getActiveSegments())
     segmentRatios.put(segment.getName(), 1.0 * segment.onDiskSize() / segment.contentSize());
   return segmentRatios;
 }
 public List<String> getActiveSegmentNames() {
   List<String> segmentNames = new ArrayList<>();
   for (CommitLogSegment segment : allocator.getActiveSegments())
     segmentNames.add(segment.getName());
   return segmentNames;
 }