@Override
      public ICachedMNode next() {
        ICachedMNode curNode = queue.poll();
        if (!curNode.isMeasurement() && curNode.getChildren().size() > 0) {
          for (ICachedMNode child : curNode.getChildren().values()) {
            queue.add(child);
          }
        }
        return curNode;
      }
related methods shall be merged further: {@linkplain SchemaFile#reEstimateSegSize}
,{@linkplain PageManager#reEstimateSegSize}
iotdb-core/datanode/src/test/java/org/apache/iotdb/db/metadata/mtree/schemafile/SchemaFileTest.java