unmarshal_large_dataset_1.go

func readBookDataset(protoInFile string) error {
	var rLen uint32
	var book typedefs.Book

	r, err := os.Open(protoInFile)
	if err != nil {
		return err
	}
	defer r.Close()

	for {
		bl := make([]byte, 4)
		n, err := r.Read(bl)
		if err == io.EOF {
			break
		}
		if err != nil {
			return err
		}
		
    		//Read 4 bytes and convert to uint32 length of message
   		 rLen = binary.LittleEndian.Uint32(bl)
    		//Read the message next
		buf := make([]byte, rLen)
		_, err = r.Read(buf)

		if err == io.EOF {
			break
		}
		if err != nil {
			return err
		}
		//Unmarshal to Book struct
		if err = proto.Unmarshal(buf, &book); err != nil {
			return err
		}
		fmt.Printf("Title: %s \nAuthor: %s \nISBN: %s \nOverview: %s\n\n", book.Title, book.Author, book.Isbn, book.Overview)
	}
	return nil

}