CSV Reader

csv_reader.go

package main

import (
	"encoding/csv"

	"flag"

	"fmt"

	"io"

	ccsv "github.com/tsak/concurrent-csv-writer"

	// "math/rand"

	"os"

	"strconv"

	"strings"

	"sync"

	"time"
)

var filename = flag.String("f", "REQUIRED", "source CSV file")

var numChannels = flag.Int("c", 4, "num of parallel channels")

var outFile, err = ccsv.NewCsvWriter("output.csv")

//var bufferedChannels = flag.Bool("b", false, "enable buffered channels")

var wg sync.WaitGroup

func main() {

	start := time.Now()

	flag.Parse()

	fmt.Print(strings.Join(flag.Args(), "\n"))

	if *filename == "REQUIRED" {

		return

	}

	defer outFile.Close()

	csvfile, err := os.Open(*filename)

	if err != nil {

		fmt.Println(err)

		return

	}

	defer csvfile.Close()

	reader := csv.NewReader(csvfile)

	i := 0

	for {

		record, err := reader.Read()

		if err == io.EOF {

			break

		} else if err != nil {

			fmt.Println(err)

			return

		}

		i++

		wg.Add(1)

		go processData(i, record)

	}

	wg.Wait()
	fmt.Printf("\n%2fs", time.Since(start).Seconds())

}

func processData(i int, r []string) {
	fmt.Println(r[0])

	i, err := strconv.Atoi(r[0])

	if err != nil {

		// handle error

		fmt.Println(err)

		// os.Exit(2)

	}

	j := i + 1

	t := strconv.Itoa(j)

	r[0] = t

	outFile.Write(r)

	defer wg.Done()
}