how do u use this thing

[go-redsync]

how do u use this thing

[MaerF0x0]

probably doesnt even compile.

func del_key(key string) (bool, error) {
    redisUrl := "redis://localhost:6379"
    p := &redis.Pool{
        Dial: func() (redis.Conn, error) {
            c, err := redis.DialURL(redisUrl)
            return c, err
        },
    }
    rs := redsync.New([]Pool{p})

    m := rs.NewMutex("GLOBAL")

    var err error

    if err := m.Lock(); err != nil {
        fmt.Println("Failed", err)
    } else {
        fmt.Println("Acquired")
        defer m.Unlock()
    }

    c := p.Get()
    defer c.Close()
    return c.Do("DEL", "something")
}

[hjr265]

@MaerF0x0 I suppose you mean the snippet above doesn't compile. I tried it out locally with Redsync and Redigo. Had to make two tiny changes to get it through the compiler:

func del_key(key string) (interface{}, error) {
    redisUrl := "redis://localhost:6379"
    p := &redis.Pool{
        Dial: func() (redis.Conn, error) {
            c, err := redis.DialURL(redisUrl)
            return c, err
        },
    }
    rs := redsync.New([]redsync.Pool{p})

    m := rs.NewMutex("GLOBAL")

    if err := m.Lock(); err != nil {
        fmt.Println("Failed", err)
    } else {
        fmt.Println("Acquired")
        defer m.Unlock()
    }

    c := p.Get()
    defer c.Close()
    return c.Do("DEL", "something")
}

[SebastiaanKlippert]

Thanks for the sample. I am correct in assuming I can create one global Redsync var using redsync.New([]Pool{p}) or do I need a new one for each mutex?

I have done some tests using the global var using the race detector and it seems to run OK, but I am not sure because the pool is shared in NewMutex.

Also, if we have multiple Go instances (load balanced environment), will a single mutex be sufficient? I looks like you are using a local mutex inside the redsync mutex so on one instance it will work, but what if two or more Go instances will lock the same value? https://redis.io/topics/distlock talks about multiple Redis instances, but I am unsure how that translates to multiple Go instances.

Sorry if this is a novice question, but I think the docs could have some more info about the use cases and I am trying to "Make sure I understand how it works before using it in production environments." 😃
Thanks.

[edit]
After doing some more testing with multiple go instances it seems to work OK.

[hjr265]

Hi @SebastiaanKlippert, thanks for trying it out. Glad to know it is working for you OK!