补充ICache

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
namespace System
{

    /// <summary>
    /// 一个接口,表示缓存
    /// </summary>
    /// <typeparam name="TKey"></typeparam>
    /// <typeparam name="TValue"></typeparam>
    public interface ICache<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>>
    {
        /// <summary>
        /// 获取当前缓存的数量
        /// </summary>
        int Count { get; }

        IEnumerable<TKey> Keys { get; }

        /// <summary>
        /// 是否包含键
        /// </summary>
        bool ContainsKey(TKey key);

        /// <summary>
        /// 查询缓存
        /// </summary>
        /// <param name="key"></param>
        /// <param name="factory"></param>
        /// <returns></returns>
        TValue Get(TKey key, Func<TValue> factory);

        ///// <summary>
        ///// 查询缓存
        ///// </summary>
        ///// <param name="key"></param>
        ///// <returns></returns>
        //TValue Get(TKey key);

        /// <summary>
        /// 查询缓存
        /// </summary>
        /// <param name="key"></param>
        /// <param name="factory"></param>
        /// <returns></returns>
        Task<TValue> GetAsync(TKey key, Func<Task<TValue>> factory);

        ///// <summary>
        ///// 查询缓存
        ///// </summary>
        ///// <param name="key"></param>
        ///// <returns></returns>
        //Task<TValue> GetAsync(TKey key);

        /// <summary>
        /// 获取数据,没有返回默认值
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        TValue this[TKey key] { get; set; }

        /// <summary>
        /// 清空缓存
        /// </summary>
        void Flush();

        /// <summary>
        /// 更新缓存
        /// </summary>
        /// <param name="key"></param>
        /// <param name="value"></param>
        /// <returns></returns>
        bool Update(TKey key, TValue value);

        /// <summary>
        /// 添加缓存
        /// </summary>
        /// <param name="key"></param>
        /// <param name="value"></param>
        /// <returns></returns>
        bool Add(TKey key, TValue value);

        /// <summary>
        /// 添加或更新缓存
        /// </summary>
        /// <param name="key"></param>
        /// <param name="value"></param>
        /// <returns></returns>
        void AddOrUpdate(TKey key, TValue value);

        /// <summary>
        /// 移除缓存
        /// </summary>
        /// <param name="key"></param>
        /// <param name="value"></param>
        /// <returns></returns>
        bool Remove(TKey key);

    }
}

using System.Collections;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using System.Linq;

namespace System
{

    internal class Cache<TKey, TValue> : ICache<TKey, TValue>
    {
        Dictionary<TKey, TValue> _map = new Dictionary<TKey, TValue>();
        ReaderWriterLockSlim _lock = new ReaderWriterLockSlim();

        SemaphoreSlim _asyncLock;

        SemaphoreSlim AsyncLock
        {
            get
            {
                if (_asyncLock == null)
                {
                    _asyncLock = new SemaphoreSlim(1, 1);
                }
                return _asyncLock;
            }
        }

        public int Count
        {
            get
            {
                return _map.Count;
            }
        }

        public IEnumerable<TKey> Keys
        {
            get
            {
                return _map.Keys;
            }
        }

        #region Get
        public TValue Get(TKey key, Func<TValue> factory)
        {
            // Check cache
            _lock.EnterReadLock();
            TValue val;
            try
            {
                if (_map.TryGetValue(key, out val))
                    return val;
            }
            finally
            {
                _lock.ExitReadLock();
            }

            // Cache it
            _lock.EnterWriteLock();
            try
            {
                // Check again
                if (_map.TryGetValue(key, out val))
                    return val;

                // Create it
                val = factory();

                // Store it
                _map.Add(key, val);

                // Done
                return val;
            }
            finally
            {
                _lock.ExitWriteLock();
            }
        }

        //public TValue Get(TKey key)
        //{
        //    // Check cache
        //    _lock.EnterReadLock();
        //    TValue val;
        //    try
        //    {
        //        _map.TryGetValue(key, out val);
        //        return val;
        //    }
        //    finally
        //    {
        //        _lock.ExitReadLock();
        //    }
        //}

        public async Task<TValue> GetAsync(TKey key, Func<Task<TValue>> factory)
        {
            // Check cache
            //_lock.EnterReadLock();
            await AsyncLock.WaitAsync(-1);
            TValue val;
            try
            {
                if (_map.TryGetValue(key, out val))
                    return val;
            }
            finally
            {
                AsyncLock.Release();
                //_lock.ExitReadLock();
            }

            // Cache it
            //_lock.EnterWriteLock();
            await AsyncLock.WaitAsync(-1);
            try
            {
                // Check again
                if (_map.TryGetValue(key, out val))
                    return val;

                // Create it
                val = await factory();

                // Store it
                _map.Add(key, val);

                // Done
                return val;
            }
            finally
            {
                //_lock.ExitWriteLock();
                AsyncLock.Release();
            }
        }

        //public async Task<TValue> GetAsync(TKey key)
        //{
        //    // Check cache
        //    //_lock.EnterReadLock();
        //    await AsyncLock.WaitAsync(-1);
        //    TValue val;
        //    try
        //    {
        //        _map.TryGetValue(key, out val);
        //        return val;
        //    }
        //    finally
        //    {
        //        AsyncLock.Release();
        //        //_lock.ExitReadLock();
        //    }

        //}

        #endregion

        /// <summary>
        /// 获取数据,没有返回默认值
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        public TValue this[TKey key]
        {
            get
            {
                _lock.EnterReadLock();
                TValue val;
                try
                {
                    if (_map.TryGetValue(key, out val))
                        return val;
                }
                finally
                {
                    _lock.ExitReadLock();
                }
                return default(TValue);
            }
            set
            {
                AddOrUpdate(key, value);
            }
        }

        public bool Update(TKey key, TValue value)
        {
            _lock.EnterReadLock();
            TValue val;
            try
            {
                if (!_map.TryGetValue(key, out val))
                    return false;
                //val = value;
                _map[key] = value;
                return true;
            }
            finally
            {
                _lock.ExitReadLock();
            }
        }

        public bool Add(TKey key, TValue value)
        {
            _lock.EnterReadLock();
            TValue val;
            try
            {
                if (_map.TryGetValue(key, out val))
                    return false;
                _map.Add(key, value);
                return true;
            }
            finally
            {
                _lock.ExitReadLock();
            }
        }

        public void AddOrUpdate(TKey key, TValue value)
        {
            _lock.EnterReadLock();
            TValue val;
            try
            {
                if (_map.TryGetValue(key, out val))
                    // val = value;
                    _map[key] = value;
                else
                    _map.Add(key, value);
            }
            finally
            {
                _lock.ExitReadLock();
            }

        }

        public bool Remove(TKey key)
        {
            _lock.EnterReadLock();
            try
            {
                return _map.Remove(key);
            }
            finally
            {
                _lock.ExitReadLock();
            }
        }

        public void Flush()
        {
            // Cache it
            _lock.EnterWriteLock();
            try
            {
                _map.Clear();
            }
            finally
            {
                _lock.ExitWriteLock();
            }

        }

        public bool ContainsKey(TKey key)
        {
            _lock.EnterReadLock();
            TValue val;
            try
            {
                if (_map.TryGetValue(key, out val))
                    return true;
                return false;
            }
            finally
            {
                _lock.ExitReadLock();
            }
        }

        public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
        {
            return _map.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return ((IEnumerable)_map).GetEnumerator();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace System
{
    /// <summary>
    /// 缓存工厂
    /// </summary>
    public static class CacheFactory
    {

        internal static readonly List<Action> _actions;

        internal static readonly Timer _timer;

        static CacheFactory()
        {
            _expireTime = 60;
            _actions = new List<Action>();
            _timer = new Timer(o =>
            {
                var actions = o as IEnumerable<Action>;

                object lockObj = new object();

                lock (lockObj)
                {
                    foreach (var item in actions)
                    {
                        try
                        {
                            item();
                        }
                        catch
                        {
                        }
                    }
                }
            }, _actions, Timeout.Infinite, Timeout.Infinite);

            int time = 1000 * 60 * _expireTime;
            _timer.Change(time, time);
        }

        static int _expireTime;
        /// <summary>
        /// 获取或设置过期时间
        /// </summary>
        public static int ExpireTime
        {
            get { return _expireTime; }
            set
            {
                _expireTime = value;
                int time = 1000 * 60 * _expireTime;
                _timer.Change(time, time);
            }
        }

        /// <summary>
        /// 创建一个缓存
        /// </summary>
        /// <typeparam name="TKey"></typeparam>
        /// <typeparam name="TValue"></typeparam>
        /// <returns></returns>
        public static ICache<TKey, TValue> CreateCache<TKey, TValue>()
        {
            return new Cache<TKey, TValue>();
            //return ActivatorFactory.CreateInstance<ICache<TKey, TValue>>();
        }

        /// <summary>
        /// 创建一个过期缓存
        /// </summary>
        /// <typeparam name="TKey"></typeparam>
        /// <typeparam name="TValue"></typeparam>
        /// <returns></returns>
        public static IExpireCache<TKey, TValue> CreateExpireCache<TKey, TValue>()
        {
            return new ExpireCache<TKey, TValue>();
            //return ActivatorFactory.CreateInstance<IExpireCache<TKey, TValue>>();
        }

        /// <summary>
        /// 创建一个过期缓存
        /// </summary>
        /// <typeparam name="TKey"></typeparam>
        /// <typeparam name="TValue"></typeparam>
        /// <returns></returns>
        public static IExpireCache<TValue> CreateExpireCache<TValue>()
        {
            return new ExpireCache<TValue>();
            //return ActivatorFactory.CreateInstance<IExpireCache<TValue>>();
        }

    }
}