Buffer or Buffered IO, multiple times or at once

buffer_or_bufio.go

package main

import (
    "bufio"
    "bytes"
    "fmt"
    "io"
    "testing"
)

var Space = []byte(" ")

func writeThroughBufferedIO(buf io.Writer) {
    w := bufio.NewWriter(buf)
    w.WriteString("hoge")
    w.WriteRune(' ')
    w.WriteString("fuga")
    w.WriteRune(' ')
    w.WriteString("foo")
    w.WriteRune(' ')
    w.WriteString("bar")
    w.Flush()
}

func Test_writeThroughBufferedIO(t *testing.T) {
    buf := new(bytes.Buffer)
    writeThroughBufferedIO(buf)

    if "hoge fuga foo bar" != buf.String() {
        t.Error("expected 'hoge fuga foo bar' but got", buf.String())
    }
}

func Benchmark_writeThroughBufferedIO(b *testing.B) {
    for i := 0; i < b.N; i++ {
        buf := new(bytes.Buffer)
        writeThroughBufferedIO(buf)
    }
}

func writeToBuffer(buf io.Writer) {
    buf.Write([]byte("hoge"))
    buf.Write(Space)
    buf.Write([]byte("fuga"))
    buf.Write(Space)
    buf.Write([]byte("foo"))
    buf.Write(Space)
    buf.Write([]byte("bar"))
}

func Test_writeToBuffer(t *testing.T) {
    buf := new(bytes.Buffer)
    writeToBuffer(buf)

    if "hoge fuga foo bar" != buf.String() {
        t.Error("expected 'hoge fuga foo bar' but got", buf.String())
    }
}

func Benchmark_writeToBuffer(b *testing.B) {
    for i := 0; i < b.N; i++ {
        buf := new(bytes.Buffer)
        writeToBuffer(buf)
    }
}

func writeThroughBufferedIOAtOnce(buf io.Writer) {
    w := bufio.NewWriter(buf)
    w.WriteString(fmt.Sprintf("%s %s %s %s", "hoge", "fuga", "foo", "bar"))
    w.Flush()
}

func Test_writeThroughBufferedIOAtOnce(t *testing.T) {
    buf := new(bytes.Buffer)
    writeThroughBufferedIOAtOnce(buf)

    if "hoge fuga foo bar" != buf.String() {
        t.Error("expected 'hoge fuga foo bar' but got", buf.String())
    }
}

func Benchmark_writeThroughBufferedIOAtOnce(b *testing.B) {
    for i := 0; i < b.N; i++ {
        buf := new(bytes.Buffer)
        writeThroughBufferedIOAtOnce(buf)
    }
}

func writeToBufferAtOnce(buf io.Writer) {
    fmt.Fprintf(buf, "%s %s %s %s", "hoge", "fuga", "foo", "bar")
}

func Test_writeToBufferAtOnce(t *testing.T) {
    buf := new(bytes.Buffer)
    writeToBufferAtOnce(buf)

    if "hoge fuga foo bar" != buf.String() {
        t.Error("expected 'hoge fuga foo bar' but got", buf.String())
    }
}

func Benchmark_writeToBufferAtOnce(b *testing.B) {
    for i := 0; i < b.N; i++ {
        buf := new(bytes.Buffer)
        writeToBufferAtOnce(buf)
    }
}

/***
Benchmark_writeThroughBufferedIO-4               2000000               817 ns/op
Benchmark_writeToBuffer-4                       10000000               233 ns/op
Benchmark_writeThroughBufferedIOAtOnce-4         1000000              1021 ns/op
Benchmark_writeToBufferAtOnce-4                  5000000               239 ns/op
***/