Cache.cs

using sage.ew.global;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Web.Caching;

namespace sage.ew.global
{
    internal class Cache<TKey, TValue>
    {
        private readonly Dictionary<TKey, CacheItem<TValue>> _cache = new Dictionary<TKey, CacheItem<TValue>>();
        public void Store(TKey key, TValue value, TimeSpan expiresAfter)
        {
            _cache[key] = new CacheItem<TValue>(value, expiresAfter);
        }
        public void Store(TKey key, TValue value)
        {
            _cache[key] = new CacheItem<TValue>(value);
        }

        public TValue Get(TKey key)
        {
            if (!_cache.ContainsKey(key)) return default(TValue);

            var cached = _cache[key];
            if ( cached.ExpiresAfter != null &&
                DateTimeOffset.Now - cached.Created >= cached.ExpiresAfter)
            {
                _cache.Remove(key);
                return default(TValue);
            }
            return cached.Value;
        }
    }
    
    internal class CacheItem<T>
    {
        public CacheItem(T value, TimeSpan expiresAfter)
        {
            Value = value;
            ExpiresAfter = expiresAfter;
        }
        public CacheItem(T value)
        {
            Value = value;
        }
        public T Value { get; }
        internal DateTimeOffset Created { get; } = DateTimeOffset.Now;
        internal TimeSpan? ExpiresAfter { get; }
    }
 }