Implementing cache correctly in a class library for use in an asp.net application?

In my opinion, the best solution would have the following characteristics.

Up vote 7 down vote favorite 4 share g+ share fb share tw.

I'm implementing a cache in a class library that i'm using in an asp.net" rel="nofollow">asp.net application. I created my cache object as a singleton pattern with a static method to update the cache which is really just loading a member variable/property with a collection of data I need cached (got some locking logic ofcourse). I figured it was a nice way to go since I can just access my data by calling MyCacheObject.Instance.

MyDataCollection I'm creating a new cache object to store a pretty big amount of data partitioned by some key. What i'm saying is i'm creating a new cache but this one will not load all of the data at once, but rather store a collection for each key accessed. MyOtherCacheObject.Instance.

MyOtherDataCollection(indexkey) This time the question about garbage collection was brought up. Since i'm storing a huge amount of data, wouldn't it be a waste if it got gc'ed all of a sudden? Since it's just a singleton pattern there is nothing ensuring data will stay in cache.

So my question is - what is best practice for implemeting a cache to handle this situation? I really don't like a huge complex solution to this, and I know there is caching in System. Web but that seems a bit 'off' since this is just a class library, or what do you think?

C# asp.net" rel="nofollow">asp.net caching garbage-collection singleton link|improve this question asked Oct 1 '08 at 6:38Per Hornshøj-Schierbeck3,23882445 100% accept rate.

In my opinion, the best solution would have the following characteristics: Uses the available caching services provided by the platform trying to avoid writing your own. Does not couple your class library to System. Web, in order to have the layers coherent.

But if the class library is running inside an ASP.NET" rel="nofollow">ASP.NET application the solution should not require to bring another caching implementation on (for example, the Enterprise Library Caching Application Block), which requires additional configuration and setup. So, I would use an IoC strategy in order to allow the class library to use different caching implementations, based on the environment it is running on. Suppose you define your abstract caching contract as: public interface ICacheService { AddItem(...); } You could provide an implementation based on System.

Web: public AspNetBasedCacheService : ICacheService { AddItem(...) { // Implementation that uses the HttpContext. Cache object } } And then have that implementation 'published' as singleton. Note that the difference with your original approach is that the singleton is just a reference to the ASP.NET" rel="nofollow">ASP.NET cache service based implementation, instead of the full 'cache object'.

Public class ChacheServiceProvider { public static IChacheService Instance {get; set;} } You would have to initialize the chaching implementation either by performing lazy initialization, or at application startup (in global.asax.cs) And every domain component would be able to use the published caching service without knowing that it is implemented based on System.Web. // inside your class library: IChacheService chache = CacheServiceProvider. Instance; cache.

AddItem(...); I agree that it is probably not the simplest solution, but I'm aiming for taking advantage of the ASP.NET" rel="nofollow">ASP.NET cache implementation without sacrificing code decoupling and flexibility. I hope I understood your question right.

I like what you are getting at (even though i'd go a long way to avoid IoC). You are bringing up some good ideas that I can run with though. Thanks – Per Hornshøj-Schierbeck Oct 1 '08 at 7:28 You could also add a backing variable and perform a lock on that variable if the set is performed.

My gut feeling says it might prevent some threading issues. – Kees C. Bakker Mar 26 '11 at 12:42.

The data wouldn't get garbage collected as long as the cache still holds a reference to it. Also, don't ever use Singletons.

But i'm afraid the cacheobject would get gc'ed not the data it caches. – Per Hornshøj-Schierbeck Oct 1 '08 at 6:42 1 also instead of using a singleton to hold my cache, what would be a better approach? – Per Hornshøj-Schierbeck Oct 1 '08 at 6:43 Why would the cache object get garbage collected?

So long as there is a reference to it, this cannot happen – 1800 INFORMATION Oct 1 '08 at 6:45 "Also, don't ever use Singletons. " - there are still legitimate uses for singletons, especially for interface implementation (since you can't have static interfaces). – Marc Gravell?

Oct 1 '08 at 6:46 My point is that where is that reference? The reference would only exist during an asp.net page request. Assuming the site is under heavy load, there might be atleast one reference at a time, but it's not a very-many-user site so who is there to hold the reference?

– Per Hornshøj-Schierbeck Oct 1 '08 at 6:48.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.