What is the best way to lock cache in asp.net?

Question

I know in certain circumstances, such as long running processes, it is important to lock ASP.NET cache in order to avoid subsequent requests by another user for that resourc

Answer 1

I have come up with the following extension method:

private static readonly object _lock = new object();

public static TResult GetOrAdd(this Cache cache, string key, Func action, int duration = 300) {
    TResult result;
    var data = cache[key]; // Can't cast using as operator as TResult may be an int or bool

    if (data == null) {
        lock (_lock) {
            data = cache[key];

            if (data == null) {
                result = action();

                if (result == null)
                    return result;

                if (duration > 0)
                    cache.Insert(key, result, null, DateTime.UtcNow.AddSeconds(duration), TimeSpan.Zero);
            } else
                result = (TResult)data;
        }
    } else
        result = (TResult)data;

    return result;
}

I have used both @John Owen and @user378380 answers. My solution allows you to store int and bool values within the cache aswell.

Please correct me if there's any errors or whether it can be written a little better.