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

Just to echo what Pavel said, I believe this is the most thread safe way of writing it

private T GetOrAddToCache(string cacheKey, GenericObjectParamsDelegate creator, params object[] creatorArgs) where T : class, new()
    {
        T returnValue = HttpContext.Current.Cache[cacheKey] as T;
        if (returnValue == null)
        {
            lock (this)
            {
                returnValue = HttpContext.Current.Cache[cacheKey] as T;
                if (returnValue == null)
                {
                    returnValue = creator(creatorArgs);
                    if (returnValue == null)
                    {
                        throw new Exception("Attempt to cache a null reference");
                    }
                    HttpContext.Current.Cache.Add(
                        cacheKey,
                        returnValue,
                        null,
                        System.Web.Caching.Cache.NoAbsoluteExpiration,
                        System.Web.Caching.Cache.NoSlidingExpiration,
                        CacheItemPriority.Normal,
                        null);
                }
            }
        }

        return returnValue;
    }