Golang redis pub/sub example

pubsub.go

package pubsub

import (
	"github.com/garyburd/redigo/redis"
	log "github.com/sirupsen/logrus"
)

// Service service
type Service struct {
	pool *redis.Pool
	conn redis.Conn
}

// NewInput input for constructor
type NewInput struct {
	RedisURL string
}

// New return new service
func New(input *NewInput) *Service {
	if input == nil {
		log.Fatal("input is required")
	}
	var redispool *redis.Pool
	redispool = &redis.Pool{
		Dial: func() (redis.Conn, error) {
			return redis.Dial("tcp", input.RedisURL)
		},
	}

	// Get a connection
	conn := redispool.Get()
	defer conn.Close()
	// Test the connection
	_, err := conn.Do("PING")
	if err != nil {
		log.Fatalf("can't connect to the redis database, got error:\n%v", err)
	}

	return &Service{
		pool: redispool,
		conn: conn,
	}
}

// Publish publish key value
func (s *Service) Publish(key string, value string) error {
	conn := s.pool.Get()
	conn.Do("PUBLISH", key, value)
	return nil
}

// Subscribe subscribe
func (s *Service) Subscribe(key string, msg chan []byte) error {
	rc := s.pool.Get()
	psc := redis.PubSubConn{Conn: rc}
	if err := psc.PSubscribe(key); err != nil {
		return err
	}

	go func() {
		for {
			switch v := psc.Receive().(type) {
			case redis.PMessage:
				msg <- v.Data
			}
		}
	}()
	return nil
}

pubsub_test.go

package pubsub

import (
	"fmt"
	"log"
	"os"
	"testing"
	"time"
)

func TestPublish(t *testing.T) {
	t.Parallel()
	svc := New(&NewInput{
		RedisURL: os.Getenv("REDIS_URL"),
	})

	err := svc.Publish("test/foo", "bar")
	if err != nil {
		log.Fatal(err)
	}
}

func TestSubscribe(t *testing.T) {
	t.Parallel()
	svc := New(&NewInput{
		RedisURL: os.Getenv("REDIS_URL"),
	})
	channel := fmt.Sprintf("test/%s", time.Now().Add(10*time.Second).String())
	val := time.Now().String()

	reply := make(chan []byte)
	err := svc.Subscribe(channel, reply)
	if err != nil {
		log.Fatal(err)
	}

	err = svc.Publish(channel, val)
	if err != nil {
		log.Fatal(err)
	}

	t.Run("message", func(t *testing.T) {
		msg := <-reply
		if string(msg) != val {
			t.Fatal("expected correct reply message")
		}
		log.Printf("recieved %q", string(msg))
	})
}

how do you unsubscribe a channel?

how do you unsubscribe a channel?

I guess you can close the connection (not the pool) as it makes a new connection for each subscription

There is unsubscribe redis command
https://redis.io/commands/unsubscribe

I assume hongnguyenhuu96 meant how to unsubscribe using this library.

According to the documentation (here https://pkg.go.dev/github.com/gomodule/redigo/redis#PubSubConn.PUnsubscribe ) you'd call the PUnsubscribe() method on PubSubConn with the according channel. So in this example it would be:

psc.PUnsubscribe(key)