producer-consumer problem with message passing

producer-consumer-problem1.go

package main

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

func init() {
	rand.Seed(time.Now().UnixNano())
}

type Result struct {
	s   string
	err error
}

type Message struct {
	input      string
	resultChan chan Result
}

type Queue struct {
	q        [32]string
	i        int
	popChan  chan Message
	pushChan chan Message
}

func (q *Queue) Push(s string) error {
	resultChan := make(chan Result)
	q.pushChan <- Message{
		input:      s,
		resultChan: resultChan}
	result := <-resultChan
	return result.err
}

func (q *Queue) Pop() (string, error) {
	resultChan := make(chan Result)
	q.popChan <- Message{
		resultChan: resultChan}
	result := <-resultChan
	return result.s, result.err
}

func (q *Queue) Controller() {
	q.popChan = make(chan Message)
	q.pushChan = make(chan Message)
	for {
		select {
		case message := <-q.pushChan:
			err := q.push(message.input)
			message.resultChan <- Result{err: err}
		case message := <-q.popChan:
			s, err := q.pop()
			message.resultChan <- Result{
				s:   s,
				err: err}
		}
	}

}

func (q *Queue) push(s string) error {
	if q.i == 31 {
		return errors.New("Full")
	}
	q.i++
	q.q[q.i] = s
	return nil
}

func (q *Queue) pop() (string, error) {
	if q.i == 0 {
		return "", errors.New("Full")
	}
	q.i--
	return q.q[q.i], nil
}

func (q *Queue) Len() int {
	return q.i
}

func main() {
	var queue = new(Queue)
	go queue.Controller()
	go consumer(queue)
	producer(queue)
}

func consumer(queue *Queue) {
	for {
		l := queue.Len()
		for i := 0; i < l; i++ {
			s, err := queue.Pop()
			fmt.Printf("read: %s, %v\n", s, err)
			if err != nil {
				time.Sleep(1 * time.Second)
				break
			}
		}
	}
}

func producer(queue *Queue) {
	for {
		l := queue.Len()
		for i := l; i < 32; i++ {
			s := randomString()
			err := queue.Push(s)
			fmt.Printf("wrote: %s, %v\n", s, err)
			if err != nil {
				time.Sleep(1 * time.Second)
				break
			}
		}
	}
}

func randomString() string {
	w := make([]byte, 5)
	rand.Read(w)
	return fmt.Sprintf("%X", w)
}