Automatically re-populate the cache at expiry time

Question

I currently cache the result of a method invocation.

The caching code follows the standard pattern: it uses the item in the cache if it exists, otherwise it calculates t

Answer 1

Here's a cache that never expires anything:

var cache = new ConcurrentDictionary();

var value = cache.GetOrAdd(someKey, key => MyMethod(key));

Does that help?

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Here's a cache that never expires anything and refreshes the value after a certain lifetime:

var cache = new ConcurrentDictionary>();

var value = cache.AddOrUpdate(someKey,
             key => Tuple.Create(MyMethod(key), DateTime.Now),
    (key, value) => (value.Item2 + lifetime < DateTime.Now)
                  ? Tuple.Create(MyMethod(key), DateTime.Now)
                  : value)
                  .Item1;

Does that help?