future-blog-post-16

client4.go

func main() {
    a := 10
    f := future.New(func() (interface{}, error) {
        return doSomethingThatTakesAWhile(a)
    }).Then(func(v interface{}) (interface{}, error) {
        return doAnotherThing(v.(int))
    })

    go func() {
        time.Sleep(1 * time.Second)
        fmt.Println(“cancelling f!”)
        f.Cancel()
    }()

    val, err := f.Get()
    fmt.Println(val, err, f.IsCancelled())

    g := future.New(func() (interface{}, error) {
        return doSomethingThatTakesAWhile(a)
    }).Then(func(v interface{}) (interface{}, error) {
        return doAnotherThing(v.(int))
    })

    go func() {
        time.Sleep(3 * time.Second)
        fmt.Println(“Cancelling g!”)
        g.Cancel()
    }()

    val2, err2 := g.Get()
    fmt.Println(val2, err2, g.IsCancelled())

    // once done happens, IsCancelled will never return true
    // and Get still has the calculated values
    time.Sleep(2 * time.Second)
    val2, err2 = g.Get()
    fmt.Println(val2, err2, g.IsCancelled())
}