Context WithCancel dan Context Done

Context With Cancel

Context WithCancel digunakan untuk mengakhiri context.

package main

import (
	"context"
	"fmt"
	"time"
)

func main() {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	go func() {
		fmt.Println("before cancel")
		time.Sleep(2 * time.Second)
		cancel()
		fmt.Println("after cancel")
	}()

	select {
	case <-time.After(5 * time.Second):
		fmt.Println("more than 5 second")
	case <-ctx.Done():
		fmt.Println(ctx.Err())
	}
}

before cancel
after cancel
context canceled

Context Done

Context Done digunakan untuk cek apakah context sudah selesai atau belum. Contoh code penerapan context done seperti code dibawah ini.

package main

import (
	"context"
	"fmt"
	"time"
)

func main() {
	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
	defer cancel()

	select {
	case <-time.After(5 * time.Second):
		fmt.Println("more than 5 second")
	// jika program berjalan < 5 detik, maka case ini akan di pilih
	case <-ctx.Done():
		fmt.Println(ctx.Err())
	}
}

context deadline exceeded