csvstruct/bench_test.go

package csvstruct

import (
	"encoding/csv"
	"io"
	"io/ioutil"
	"math/rand"
	"strings"
	"testing"
	"time"
)

func BenchmarkDecode(b *testing.B) {
	in := generateCSV()
	b.ResetTimer()
	d := NewDecoder(in)
	for i := 0; i < b.N; i++ {
		var r struct{ A, B, C string }
		for {
			if err := d.DecodeNext(&r); err == io.EOF {
				break
			} else if err != nil {
				b.Errorf("DecodeNext(%q): %v", in, err)
				return
			}
		}
	}
}

func BenchmarkCSVRead(b *testing.B) {
	in := generateCSV()
	b.ResetTimer()
	r := csv.NewReader(in)
	for i := 0; i < b.N; i++ {
		if _, err := r.ReadAll(); err != nil {
			b.Errorf("ReadAll(%q): %v", in, err)
			return
		}
	}
}

func BenchmarkEncode(b *testing.B) {
	type row struct{ A, B, C string }
	rows := []row{}
	for i := 0; i < numRows; i++ {
		rows = append(rows, row{randString(), randString(), randString()})
	}
	b.ResetTimer()

	e := NewEncoder(ioutil.Discard)
	for i := 0; i < b.N; i++ {
		for _, r := range rows {
			if err := e.EncodeNext(r); err != nil {
				b.Errorf("EncodeNext(%v): %v", r, err)
				return
			}
		}
	}
}

func BenchmarkCSVWrite(b *testing.B) {
	d := [][]string{}
	for i := 0; i < numRows; i++ {
		d = append(d, []string{randString(), randString(), randString()})
	}
	b.ResetTimer()

	w := csv.NewWriter(ioutil.Discard)
	for i := 0; i < b.N; i++ {
		for _, r := range d {
			if err := w.Write(r); err != nil {
				b.Errorf("Write(%v): %v", r, err)
				return
			}
		}
	}
}

const (
	alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	strLen   = 5
	numRows  = 10
)

var r = rand.New(rand.NewSource(time.Now().Unix()))

func randString() string {
	s := ""
	for i := 0; i < strLen; i++ {
		s += string(alphabet[r.Intn(len(alphabet))])
	}
	return s
}

// TODO: Generate the CSV on-demand instead of cramming it all into memory
func generateCSV() io.Reader {
	rs := []string{"A,B,C"}
	for i := 0; i < numRows; i++ {
		rs = append(rs, strings.Join([]string{randString(), randString(), randString()}, ","))
	}
	return strings.NewReader(strings.Join(rs, "\n"))
}