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public interface SplitReader<T, SplitT> {

   /**
    * Initializes the reader and advances to the first record. Returns true
    * if a record was read. If no record was read, records might still be
    * available for reading in the future.
    */
   boolean start() throws IOException;

   /**
    * Advances to the next record. Returns true if a record was read. If no
    * record was read, records might still be available for reading in the future.
    *
    * <p>This method must return as fast as possible and not block if no records
    * are available.
    */
   boolean advance() throws IOException;

   /**
    * Returns the current record.
    */
   T getCurrent() throws NoSuchElementException;

   long getCurrentTimestamp() throws NoSuchElementException;

   long getWatermark();

   /**
    * Returns a checkpoint that represents the current reader state. The current
    * record is not the responsibility of the reader, it is assumed that the
    * component that uses the reader is responsible for that.
    */
   SplitT checkpoint();

   /**
    * Returns true if reading of this split is done, i.e. there will never be
    * any available records in the future.
    */
   boolean isDone() throws IOException;

   /**
    * Shuts down the reader.
    */
   void close() throws IOException;
}