go-by-test/racer/racer.go

package racer

import (
	"errors"
	"net/http"
	"time"
)

var ErrRacerTimeout = errors.New("timeout")

const tenSecondTimeout = 10 * time.Second

func ConfigurableRacer(a, b string, timeout time.Duration) (string, error) {
	select {
	// wait until channel closed
	case <-ping(a):
		return a, nil
	case <-ping(b):
		return b, nil
	case <-time.After(timeout):
		return "", ErrRacerTimeout
	}
}

func Racer(a, b string) (string, error) {
	return ConfigurableRacer(a, b, tenSecondTimeout)
}

func ping(url string) chan struct{} {
	ch := make(chan struct{})
	go func() {
		http.Get(url)
		// if got, close channel
		close(ch)
	}()
	return ch
}

// func measureResponseTime(url string) time.Duration {
// 	start := time.Now()
// 	http.Get(url)
// 	duration := time.Since(start)
// 	fmt.Println(duration)
// 	return duration
// }