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pubsub-noclose.go
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pubsub-noclose.go
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// PubSub implementation taking a channel as argument in Subscibe, w/o Close.
//
// Eli Bendersky [https://eli.thegreenplace.net]
// This code is in the public domain.
package main
import (
"fmt"
"sync"
"time"
)
type Pubsub struct {
mu sync.RWMutex
subs map[string][]chan string
}
func NewPubsub() *Pubsub {
ps := &Pubsub{}
ps.subs = make(map[string][]chan string)
return ps
}
func (ps *Pubsub) Subscribe(topic string, ch chan string) {
ps.mu.Lock()
defer ps.mu.Unlock()
ps.subs[topic] = append(ps.subs[topic], ch)
}
func (ps *Pubsub) Publish(topic string, msg string) {
ps.mu.RLock()
defer ps.mu.RUnlock()
for _, ch := range ps.subs[topic] {
ch <- msg
}
}
func main() {
ps := NewPubsub()
makesub := func(topic string) chan string {
ch := make(chan string, 1)
ps.Subscribe(topic, ch)
return ch
}
ch1 := makesub("tech")
ch2 := makesub("travel")
ch3 := makesub("travel")
listener := func(name string, ch chan string) {
for i := range ch {
fmt.Printf("[%s] got %s\n", name, i)
}
}
go listener("1", ch1)
go listener("2", ch2)
go listener("3", ch3)
pub := func(topic string, msg string) {
fmt.Printf("Publishing @%s: %s\n", topic, msg)
ps.Publish(topic, msg)
time.Sleep(1 * time.Millisecond)
}
time.Sleep(50 * time.Millisecond)
pub("tech", "tablets")
pub("health", "vitamins")
pub("tech", "robots")
pub("travel", "beaches")
pub("travel", "hiking")
pub("tech", "drones")
time.Sleep(50 * time.Millisecond)
}