codewars/go/habr/select.go

package main

import (
	"fmt"
	"time"
)

var start time.Time

func init() {
	fmt.Println("init...")
	start = time.Now()
}

func service1(c chan string) {
	// time.Sleep(3 * time.Second)
	fmt.Println("service1() started", time.Since(start))
	c <- "Hello from service 1"
}

func service2(c chan string) {
	// time.Sleep(5 * time.Second)
	fmt.Println("service2() started", time.Since(start))
	c <- "Hello from service 2"
}

func main() {
	selectTest()
	/*
		fmt.Println("main() started", time.Since(start))

		chan1 := make(chan string)
		chan2 := make(chan string)

		go service1(chan1)
		go service2(chan2)

		select {
		case res := <-chan1:
			fmt.Println("Response from service 1", res, time.Since(start))
		case res := <-chan2:
			fmt.Println("Response from service 2", res, time.Since(start))
		}

		fmt.Println("main() stopped", time.Since(start))
	*/
}

func selectTest() {
	fmt.Println("main() started", time.Since(start))

	chan1 := make(chan string)
	chan2 := make(chan string)

	go service1(chan1)
	go service2(chan2)

	// С этой функций в select выполнится один из кейсов
	// Без задержки будет выполнен default
	// time.Sleep(1 * time.Second)

	select {
	case res := <-chan1:
		fmt.Println("Response from service 1", res, time.Since(start))
	case res := <-chan2:
		fmt.Println("Response from service 2", res, time.Since(start))
		// default:
		// fmt.Println("No responce received", time.Since(start))
	}

	fmt.Println("main() stopped", time.Since(start))
}