ASP.NET Software Engineering

Caching Method Results in ASP.NET 2.0 using Generics & Delegates

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)
            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”

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!

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