Azure Redis - how to extend the expiration time every time key is accessed?

Question

Key: firstname Value: samurai Expiry:6 hours

 public static bool Add<T>(this IDatabase cache, string key, T value, TimeSpan? expiry = null)
        {
            dynamic response;
           
                response = cache.StringSet(key, JsonConvert.SerializeObject(value, jsonSettings), expiry, flags: CommandFlags.DemandMaster);
            }
          
            return response;
        }

Suppose at this moment there the TTL is 10mins. Ie. 5 hours and 50 mins have passed and the key will be deleted after 10 mins. But if someone performs a get operation on this key. The expiry should reset to 6 hours again.

One simple way to do this is to just perform cache.StringSet again. But I am afraid that may degrade performance under heavy load test. Are there any alternatives?

Answer 1

To achieve a sliding expiration, you can issue a KeyExpire[Async] when you call StringGet . Since you don't need to know the result of this, you can use FireAndForget to avoid any latency cost - ie it won't count as a second round-trip:

cache.KeyExpire(key, TimeSpan.FromHours(6), CommandFlags.FireAndForget);
var val = cache.StringGet(key);

Another approach would be to wrap this in Lua via ScriptEvaluate and perform both operations there, but I don't think this is necessary here - the KeyExpire and StringGet pair should be fine.