#ChnGoTurns10

pubsub.go

package main

import (
	"fmt"
	"sync"
	"time"
)

type Subscriber func(int)

type PubSub struct {
	ch              chan int
	Subscribers     []Subscriber
	subscriberMutex sync.RWMutex
}

func (p *PubSub) Publish(val int) {
	p.ch <- val

	fmt.Println("DEBUG: Publishing - ", val)
}

func (p *PubSub) Subscribe(s Subscriber) {
	p.subscriberMutex.Lock()
	p.Subscribers = append(p.Subscribers, s)
	p.subscriberMutex.Unlock()
}

func NewPubSub() *PubSub {
	var pubSub PubSub

	pubSub.ch = make(chan int)

	go func() {
		for {
			val := <-pubSub.ch

			fmt.Println("DEBUG: Notifying subscribers - ", val)

			pubSub.subscriberMutex.RLock()
			for _, subscriber := range pubSub.Subscribers {
				subscriber(val)
			}
			pubSub.subscriberMutex.RUnlock()
		}
	}()

	return &pubSub
}

func main() {
	p := NewPubSub()

	p.Subscribe(func(val int) {
		fmt.Println("Multiplier: ", val*10)
	})

	go p.Publish(42) // Independent
	// go p.Publish(52)
	// go p.Publish(62)

	for i := 1; i <= 10; i++ {
		k := i
		p.Subscribe(func(val int) {
			fmt.Println("Adder: ", val+k)
		})
	}

	p.Publish(100)

	time.Sleep(1 * time.Second)
}