Cache Prototype

CachePrototype.cs

    public class TripsByDateQuery : IQuery<IEnumerable<Trip>>
    {
        public DateTime? Lowerbound { get;set; }
        public DateTime? UpperBound { get; set; }
    }

    public class TripsByDateQueryHandler : IQueryHandler<TripsByDateQuery, IEnumerable<Trip>>, ICachable
    {
        public IEnumerable<Trip> Handle(TripsByDateQuery query)
        {
            //# Do stuff here
        }
    }


    public class RuntimeCachingCachableDecorator<T, U> : IQueryHandler<T, U> where T: IQuery<T>
    {
        private readonly IQueryHandler<T, U> innerHandler 

        public RuntimeCachingCachableDecorator (ICachable cachable)
        {
            this.cachable = cachable;
        }

        public U Handle(T query)
        {
            //# check to see if this query is cached.
            //# if it is, return. 
            //# if not, execute the handler, and cache the result.

            var cacheKey = GenerateCacheKey(query);

            if (Cache.ContainsKey(cacheKey))
                return Cache.GetFromCache(cacheKey) as U;

            else 
            {
                var result = innerHandler.Handle(query);
                lock(crap)
                {
                    //# Maybe lock again, but who cares.
                    Cache.AddToCache(cacheKey, result);

                    return result;
                }
            }
        }
    }

It would be nice if to enable caching, all we need to do was add the ICachable interface.

Then, let StructureMap or other IoC containers wire it up at runtime.

Say, if a IQueryHandler implements ICachable, then wrap it with the RuntimeCachingCachableDecorator

Use something like this to configure the cache entry.

public class TripsBySomeOtherDateQuery : IQuery<IEnumerable<Trip>>, ICachableConfigurationProvider
{
    public DateTime? OtherDate { get;set; }

    public ICachableConfiguration GetCachableConfiguration()
    {
        return new CachableConfiguration(
            cacheKey: "SomeCustomCacheKey",
            expiration: = TimeSpan.Hours.Add(1)
        )
    }
}