buffered_channel.go

package main

import (
	"errors"
	"fmt"
	"math/rand"
	"time"
)

func main() {
	rand.Seed(time.Now().UTC().UnixNano())

	items := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
	maxProcs := 5

	queue := make(chan int, maxProcs)
	reply := make(chan error)

	for i := 0; i < maxProcs; i++ {
		go work(queue, reply)
	}

	go broker(items, queue)

	for i := 0; i < len(items); i++ {
		err := <-reply
		if err != nil {
			fmt.Printf("error: %v\n", err)
		}
	}

	return
}

func broker(items []int, queue chan<- int) {
	for _, item := range items {
		queue <- item
	}

	close(queue)
}

func work(queue <-chan int, reply chan<- error) {
	for {
		var err error

		item, ok := <-queue
		if !ok {
			return
		}

		time.Sleep(time.Duration(rand.Intn(1000)) * time.Millisecond)

		if item != 5 {
			fmt.Println(item)
		} else {
			err = errors.New("value is 5")
		}

		reply <- err
	}
}