docker-pubsub.go

package main

import (
	"time"

	"github.com/docker/docker/pkg/pubsub"
)

func main() {
	pub := pubsub.NewPublisher(0, 1)
	sub := pub.Subscribe()

	go func() {
		for i := 0; i < 10; i++ {
			pub.Publish(i)
			time.Sleep(time.Millisecond * 500)
		}
		pub.Evict(sub)
	}()

	for {
		select {
		case i, ok := <-sub:
			if !ok {
				return
			}

			println(i.(int))
			time.Sleep(time.Second)
		}
	}
}

If the subscriber is slower than the publisher, some of the messages will be lost.

Run the code you'll find the output is something like

0
1
2
4
6
8