concurrency.go

package main

import (
	"fmt"
	"sync"
	"sync/atomic"
	"time"
)

type work struct {
	x int32
	y int32
	z int32
}

func worker(wg *sync.WaitGroup, input <-chan work, out chan<- work, counter *int32) {
	defer wg.Done()
	for w := range input {
		atomic.AddInt32(counter, 1)
		w.z = w.x * w.y
		time.Sleep(time.Duration(w.z) * time.Millisecond)
		out <- w
	}
}

func run(wg *sync.WaitGroup, workerNum int, input <-chan work, out chan<- work, counter *int32) {
	for i := 0; i < workerNum; i++ {
		wg.Add(1)
		go worker(wg, input, out, counter)
	}
}

func createWork(workNum int32, input chan<- work) {
	var (
		w work
		i int32
	)
	for i = 0; i < workNum; i++ {
		w = work{x: i, y: i}
		input <- w
	}
	close(input)
}

func consumer(output <-chan work) {
	for w := range output {
		fmt.Println(w.z)
	}
	fmt.Println("All tasks consumed.")
}
func main() {
	input, output := make(chan work, 10), make(chan work, 10)
	defer close(output)
	wg := &sync.WaitGroup{}
	var counter int32 = 0
	run(wg, 10, input, output, &counter)
	go createWork(50, input)
	go consumer(output)
	wg.Wait()
	fmt.Printf("All task was completed, total %d tasks.\n", counter)
}