code: public void freeSegment(SegmentKelp segment)
      throws IOException
    {
      // System.out.println("FREE: " + segment);
      SegmentMeta segmentMeta = findSegmentMeta(segment.length());
      
      segmentMeta.remove(segment);
      
      segment.close();
      
      segmentMeta.addFree(segment.extent());
      
      // System.out.println("  FREE: " + segmentMeta.getFreeCount() + " " + segment.getLength());
    }
docs: Frees a segment to be reused. Called by the segment-gc service.