Does CAS style transaction require DoMulti(...) #494

tm1303 · 2024-03-12T18:17:04Z

tm1303
Mar 12, 2024

The given example in the README is as follows (modified very slightly to return err, i know the ToAny() is wrong 😝)

client.Dedicated(func(c rueidis.DedicatedClient) error {
    // watch keys first
    c.Do(ctx, c.B().Watch().Key("k1", "k2").Build())
    // perform read here
    c.Do(ctx, c.B().Mget().Key("k1", "k2").Build())
    // perform write with MULTI EXEC
    _, err := c.DoMulti(
        ctx,
        c.B().Multi().Build(),
        c.B().Set().Key("k1").Value("1").Build(),
        c.B().Set().Key("k2").Value("2").Build(),
        c.B().Exec().Build(),
    ).ToAny()
    return err
})

I only have a single Set() to perform but I'm unclear if I must pass my one Set() as param to DoMulti() to benefit from the CAS style transaction or if this example is just showing us how to (optionally) perform multiple Set() within a CAS transaction.

I have one Set() to perform but it is conditional on the watched key not changing. Would the following suffice? Would this Set() fail and return an appropriate error if the watched key value changes or expires?


client.Dedicated(func(c rueidis.DedicatedClient) error {
    // watch keys first
    c.Do(ctx, c.B().Watch().Key("k1").Build())
    // perform read here
    c.Do(ctx, c.B().Get().Key("k1").Build())
    // perform single write
    _, err := c.Do(ctx, c.B().Set().Key("k1").Value("1").Build()).ToAny()

    return err
})