How to implement ServiceStack Redis Client with timeout

Question

We are implementing a pattern where our client checks to see if a document exists in Redis, and if it does not, we then fetch the data from the database.

We are trying to handle a case where the Redis server is down or unreachable so we can then immediately fetch from the database.

However, when we test our code by intentionally taking down the Redis server, the call to Redis via the ServiceStack client does not timeout for approximately 20 seconds.

We tried using the RedisClient .SendTimeout property to various values (1000, 100, 1), but the timeout always happens after approx 20 seconds. We also tried using the .Ping() method but have the same problem.

Question: how can we handle the scenario where the Redis server is down and we want to switch to a DB fetch more quickly?

Answer 1

I had a similar problem sending e-mail: sometimes there's no answer and the build-in timeout (of SmtpClient) does nothing. Eventually I'd get a timeout which I believe comes from the underlying TCP/IP layer. I'd set the timeout in the client a little shorter than the "brutal timeout" on Task.Wait.

My solution was to wrap the call in a Task, and use a timeout on that:

        // this special construct is to set a timeout (the SmtpClient timeout does not seem to work)
        var task = Task.Factory.StartNew(() => SendEmail(request));

        if (!task.Wait(6000))
            Log.Error("Could not send mail to {0}. Timeout (probably on TCP layer).".Fmt(request.To));

Maybe something similar would work for you, just replace the SendEmail with a method that does the Redis thing.