@Override
    public synchronized void mark(int readlimit) {
      this.mark = readBytes;
      inputStream.mark(readlimit);
    }
This class provides the ability to record the num of read bytes from the nested InputStream.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/logfile/SchemaLogReader.java