file create example

go-file-create.go

package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"runtime"
	"sync/atomic"
	"time"
)

var (
	filePath   = flag.String("f", "/tmp/mylog", "output file")
	duration   = flag.Duration("d", time.Second*10, "Duration of test")
	intervals  = flag.Duration("i", time.Millisecond*100, "Intervals of write per second")
	goroutines = flag.Int("g", 10, "Number of goroutines")
)

func init() {
	flag.Parse()
}

type Counter struct {
	ops uint64
}

func (c *Counter) Inc() {
	atomic.AddUint64(&c.ops, 1)
	runtime.Gosched()
}

func (c *Counter) Val() uint64 {
	return atomic.LoadUint64(&c.ops)
}

func check(e error) {
	if e != nil {
		log.Panic(e)
	}
}

func print_summary() {
	log.Println("Output :", *filePath)
	log.Println("Duration :", duration)
	log.Println("Intervals :", intervals)
	log.Println("Start!!")
}

func repeat_somthing() {
	print_summary()

	count := &Counter{}

	ticker := time.NewTicker(*intervals)
	for i := 0; i < *goroutines; i++ {
		go func() {
			for _ = range ticker.C {
				count.Inc()
				write_extlog(count.Val())
			}
		}()
	}

	noti := time.NewTicker(time.Second * 2)

	go func() {
		for _ = range noti.C {
			log.Print(".")
		}
	}()

	time.Sleep(*duration)

	ticker.Stop()
	noti.Stop()

	print_summary()
	log.Println("Stop!! Counter", count.Val())
}

func write_extlog(number uint64) {
	f, err := os.OpenFile(*filePath, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0666)
	check(err)
	defer f.Close()

	_, err = fmt.Fprintf(f, "test %d\n", number)
	check(err)
}

func main() {
	repeat_somthing()
}