code: @PublicEvolving
  	@Override
  	public Tuple2<Long, Long> getCurrentState() throws IOException {
  		if (this.blockBasedInput == null) {
  			throw new RuntimeException("You must have forgotten to call open() on your input format.");
  		}
  
  		return  new Tuple2<>(
  			this.blockBasedInput.getCurrBlockPos(), 		// the last read index in the block
  			this.readRecords								// the number of records read
  		);
  	}
docs: --------------------------------------------------------------------------------------------