code: public void freeSegment(SegmentKelp segment)
      throws IOException
    {
      freeTableSegmentLength(segment.length());
      
      // System.out.println("FREE: " + _tableLength + " " + segment.getLength() + " " + segment);
      
      _segmentService.freeSegment(segment);
    }
docs: Frees a segment to be reused. Called by the segment-gc service.