定期実行の理解

interval.go

package main

import (
        "fmt"
        "os"
        "os/signal"
        "time"
)

func doSomething() {
        fmt.Println(time.Now())
}

func main() {
        sc := make(chan os.Signal, 1)
        signal.Notify(sc, os.Interrupt)
loop:
        for {
                select {
                case <- sc:
                        fmt.Println("interrupt")
                        break loop
                        //os.Exit(0)
                case <-time.After(2 * time.Second):
                        doSomething()
                }
        }
}

withtimeout.go

package main

import (
        "context"
        "fmt"
        "os"
        "os/signal"
        "time"
)

func doSomething(ctx context.Context, i int) {
        //fmt.Println("before")
        time.Sleep(5 * time.Second)
        //fmt.Println("after")
}

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

        go doSomething(ctx, 1)

        sc := make(chan os.Signal, 1)
        signal.Notify(sc, os.Interrupt)

        //fmt.Println("sleep start")
        //time.Sleep(4*time.Second)

        select {
        case <-sc:
                cancel()
                fmt.Println("interrupt")
        case <-ctx.Done():
                fmt.Println("done:", ctx.Err())
        }
}