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Created June 20, 2015 09:51
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Golang: Playing with a queue channel
package main
import (
const (
queueSize = 9
numberOfReaders = 3
var readerSleepInterval = struct{ min, max int }{0, 2}
var queue = make(chan int, queueSize)
var done = make(chan bool)
func main() {
fmt.Println("=== Playing with a simple queue ===")
fmt.Printf(" Queue size: %v\n", queueSize)
fmt.Printf(" Number of readers: %v\n", numberOfReaders)
fmt.Printf(" Reader sleep interval from %v to %v seconds\n", readerSleepInterval.min, readerSleepInterval.max)
fmt.Printf("Forking %v readers\n ", numberOfReaders)
for i := 0; i < numberOfReaders; i++ {
fmt.Printf("#%v ", i)
go queueReader(i)
fmt.Println("Forking the Producer")
go queueProducer()
fmt.Println("Waiting for quit from the Producer")
// Producer will ask user to input number of items to put in queue
// If number exceeds the queue size, it hang until the queue can
// accept more items, then it will push more items on the queue
func queueProducer() {
reader := bufio.NewReader(os.Stdin)
for {
fmt.Printf("Number of items to add (quit to exit): ")
bytes, _, err := reader.ReadLine()
if err != nil {
val := string(bytes)
if val == "quit" {
done <- true
n, err := strconv.Atoi(val)
if err != nil {
fmt.Println("Enter a number, please!")
for i := 0; i < n; i++ {
queue <- i
// Reader will read from queue and then pretend to process it for a
// random(ish) number of seconds.
func queueReader(n int) {
for {
val := <-queue
rsi := readerSleepInterval
s := rand.Intn(rsi.max-rsi.min) + rsi.min
fmt.Printf(" Reader #%v read %v from queue, processing for %v seconds\n", n, val, s)
time.Sleep(time.Duration(s) * time.Second)
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