Future

Future API in Golang. It give flexibility to the user to use both sync and async way to get the result.

The API is not type specific. It use type Value interface{}, as we know interface{} says nothing. You can use this API or create specific implementation for each data type.

Usage

Async function

package main

func main() {
    res := doThings()
    val, _ := res.Get(context.Background())
    fmt.Println(val)
}

func doThings() *future.Future[string] {
    fut, setResult := future.New[string]()
    time.AfterFunc(10*time.Millisecond, func() {
        setResult("OK", nil)
    })
    return fut
}

Some of the function created in async manner, we can convert it as async using the future API.

package main

func main() {
    // Use sync function as async using future
    fut := future.Call(func() (string, error) {
		return greet()
    })

    v, _ := fut.Get(context.Background())
    fmt.Println(v)
}

// Sync function
func greet() (string, error) {
    time.Sleep(500 * time.Millisecond)
    return "Hello World!", nil
}

Use callback style to get the result immediately without the overhead of an extra goroutine

package main

func main() {
    done := make(chan struct{})

    res := doThings()
    res.Listen(func(val string, err error) {
        fmt.Println(val)
        close(done)
    })

    <-done
}

// Future function
func doThings() *future.Future[string] {
    fut, setResult := future.New[string]()
    time.AfterFunc(10*time.Millisecond, func() {
        setResult("OK", nil)
    })
    return fut
}