Today I found myself coding a fairly familiar pattern – checking whether there was an entry in the ASP.NET cache with a particular key, if not, executing a method and adding the result to the cache, and either way, returning the result.
I wondered whether there was a “nice” way to do this using generics and anonymous delegates. This is what I came up with…
public delegate T MethodExecution<T>();
public static T GetCachedMethod<T>(string key, DateTime absoluteExpiration, MethodExecution<T> method)
{
if (HttpContext.Current.Cache[key] == null)
HttpContext.Current.Cache.Insert(key,
method(),
null, absoluteExpiration, Cache.NoSlidingExpiration);
return (T)HttpContext.Current.Cache[key];
}
Now, to use this method,I could write the following to return a cached (by one day) result of the method SomeMethodThatReturnsADataSet.
return GetCachedMethod<DataSet>(key,DateTime.Now.AddDays(1),
delegate() { return SomeMethodThatReturnsADataSet(myParam); });
I’m not sure whether this just makes things more obscure – any comments? 🙂
3 replies on “Caching Method Results in ASP.NET 2.0 using Generics & Delegates”
This is great. Exposing this directly through an API may confuse some users. Maybe just expose a method that takes a delegate for the API. I think it is great for an internal implementation.
See my comment to your follow up post, there”s a race condition in your code.
Awesome. I had the exact same question, but then my brain started to hurt so I just Googled it and this is exactly what I was looking for.
Jerry is right though. There is a race condition (if the cache gets invalidated after the if statement executes and before the return statement executes) I have actually had this crash my site a few times!