asp.net - List<T> on Cache (Security Operations) -

i'm developing web app using asp.net mvc.

i have list in cache (list of product class of model). so, crud operations on cached list. know httpcontext.current.cache typesafe list no. i'd know, best way operations thread safe avoid conflicts ?

my code this:

public static class projectcached {     const string key = "productlist";     // cached list     public static ilist<product> products {        {            if (httpcontext.current.cache[key] == null) {               httpcontext.current.cache.insert(key, /* data database */, ...);            }            return (list<product>)httpcontext.current.cache[key];        }     }     // methods (operations on cached list)     public static void increase(long id) {         var item = products.firstordefault(x => x.id == id);         if (item != null) {           item.prince += 1;           item.lastupdate = datetime.now;         }            }      public static void remove(long id) {         var item = products.firstordefault(x => x.id == id);         if (item != null) {             products.remove(item);         }            }     // others methods  

}

i have lot of users writing on cached list @ same time...

i know can use "lock" keyword need put ? on object finded? on list?

thanks

consider using idictionary instead of list, example sortedlist<tkey, tvalue>
safe-threading: can using

1. lock keyword

2. readerwriterlockslim - lock when needed

3. concurrentdictionary<tkey, tvalue> - if thread-safe implemented in enough you.

upd: readerwriterlockslim more advanced simple lock keyword. using readerwriterlockslim allows many readers data simultaneously without locks. when thread tries write data, other threads locked , reading , writing.