@Override
  public String toString() {
    StringBuilder buf = new StringBuilder();
    int i = 1;
    try {
      for (Segment segment : getSegments()) {
        buf.append("Segment (").append(i).append(") ").append(segment.toString()).append("; ");
        i++;
      }
    } catch (IOException e) {
      return e.toString();
    }
    return buf.toString();
  }
This method is protected under {@link HStore#lock} write lock,<br/>
and this method is used by {@link HStore#updateStorefiles} after flushing is completed.<br/>
The passed snapshot was successfully persisted; it can be let go.
@param id Id of the snapshot to clean out.
@see MemStore#snapshot()
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/AbstractMemStore.java