golang-examples/example-go-channel/main.go

// https://www.digitalocean.com/community/tutorials/how-to-run-multiple-functions-concurrently-in-go
// who came up with the idea of making community tutorials. that was a good idea!

package main

import (
	"fmt"
	"sync"
)

func generateNumbers(total int, ch chan<- int, wg *sync.WaitGroup) {
	defer wg.Done()

	for idx := 1; idx <= total; idx++ {
		fmt.Printf("START sending %d to channel\n", idx)
		ch <- idx
		// res, err := (<-r)()
		fmt.Printf("END sending %d to channel\n", idx)
	}
	wg.Wait()
	fmt.Printf("END wg sending to channel\n")
}

func printInt(idx int, ch <-chan int, wg *sync.WaitGroup) {
	defer wg.Done()

	for num := range ch {
		fmt.Printf("%d: read %d from channel\n", idx, num)
	}
}

func main() {
	var wg sync.WaitGroup
	numberChan := make(chan int)

	for idx := 1; idx <= 2; idx++ {
		wg.Add(1)
		go printInt(idx, numberChan, &wg)
	}

	generateNumbers(10, numberChan, &wg)

	close(numberChan)

	fmt.Println("Waiting for goroutines to finish...")
	wg.Wait()
	fmt.Println("Done!")
}