如何在Golang中为Redis（redigo）Pubsub编写更好的Receive（）？

Question

psc := redis.PubSubConn{c}
psc.Subscribe("example")

func Receive() {
    for {
        switch v := psc.Receive().(type) {
        case redis.Message:
            fmt.Printf("%s: message: %s
", v.Channel, v.Data)
        case redis.Subscription:
            fmt.Printf("%s: %s %d
", v.Channel, v.Kind, v.Count)
        case error:
            return v
        }
    }
}

In the above code(taken from Redigo doc), if connection is lost, all subscriptions are also lost. What will be better way to recover from lost connection and resubscribe.

Answer 1

Use two nested loops. The outer loop gets a connection, sets up the subscriptions and then invokes the inner loop to receive messages. The inner loop executes until there's a permanent error on the connection.

for {
    // Get a connection from a pool
    c := pool.Get()
    psc := redis.PubSubConn{c}

    // Set up subscriptions
    psc.Subscribe("example"))

    // While not a permanent error on the connection.
    for c.Err() == nil {
        switch v := psc.Receive().(type) {
        case redis.Message:
            fmt.Printf("%s: message: %s
", v.Channel, v.Data)
        case redis.Subscription:
            fmt.Printf("%s: %s %d
", v.Channel, v.Kind, v.Count)
        case error:
            fmt.Printf(err)
        }
    }
    c.Close()
}

This example uses a Redigo pool to get connections. An alternative is to dial a connection directly:

 c, err := redis.Dial("tcp", serverAddress)