@Override
  public void syncPageBuffer() {
    this.pageBuffer.limit(this.pageBuffer.capacity());
    this.pageBuffer.position(SchemaFileConfig.PAGE_HEADER_INDEX_OFFSET);
    ReadWriteIOUtils.write(pageIndex, pageBuffer);
    ReadWriteIOUtils.write(spareOffset, pageBuffer);
    ReadWriteIOUtils.write(spareSize, pageBuffer);
    ReadWriteIOUtils.write(memberNum, pageBuffer);
  }
compatible constructor with no existing ref or lock
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/mtree/impl/pbtree/schemafile/SchemaPage.java