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What's an idiomatic way to reconnect to Redis subscription in Go?

Tags:

redis

go

redigo

I am using the redigo library to try to subscribe to a Redis channel and then handle a published message. How do I handle the case where it errors out? Here's what I came up with. Is this a good way to do it? Is there a better way?

Note: this question is specific to redigo, but I think it applies to other places where reconnections need to happen.

package main

import (
    "fmt"
    "time"

    "github.com/garyburd/redigo/redis"
)

func main() {
    for {
        fmt.Println("connecting...")
        c, err := redis.Dial("tcp", "localhost:6379")
        if err != nil {
            fmt.Println("error connecting to redis")
            time.Sleep(5 * time.Second)
            continue
        }
        psc := redis.PubSubConn{c}
        psc.Subscribe("example")
    ReceiveLoop:
        for {
            switch v := psc.Receive().(type) {
            case redis.Message:
                fmt.Printf("%s: message: %s\n", v.Channel, v.Data)
            case redis.Subscription:
                fmt.Printf("%s: %s %d\n", v.Channel, v.Kind, v.Count)
            case error:
                fmt.Println("there was an error")
                fmt.Println(v)
                time.Sleep(5 * time.Second)
                break ReceiveLoop
            }
        }
    }
}

I just put it in the main() function for the example. It would really run in some goroutine.

like image 698
Drew LeSueur Avatar asked May 01 '15 13:05

Drew LeSueur


1 Answers

Yes, using a label and a loop is standard practice for reconnecting.

The only thing you're missing is closing the connection.

            psc.Close()
            break ReceiveLoop

For a little more resilience, you may want redis.DialTimeout so that a Dial call can't hang indefinitely.

like image 118
JimB Avatar answered Oct 31 '22 15:10

JimB