Cache缓存

在大型网站中，缓存、异步、并行 核心。对外提供的一些接口数据，尤其是要注意缓存，避免别循环查数据，导致整个服务器崩溃。

缓存接口类：

{
    /// <summary>
    /// Cache manager interface
    /// </summary>
    public interface ICacheManager
    {
        /// <summary>
        /// Gets or sets the value associated with the specified key.
        /// </summary>
        /// <typeparam name="T">Type</typeparam>
        /// <param name="key">The key of the value to get.</param>
        /// <returns>The value associated with the specified key.</returns>
        T Get<T>(string key);

        /// <summary>
        /// Adds the specified key and object to the cache.
        /// </summary>
        /// <param name="key">key</param>
        /// <param name="data">Data</param>
        /// <param name="cacheTime">Cache time</param>
        void Set(string key, object data, int cacheTime);

        /// <summary>
        /// Gets a value indicating whether the value associated with the specified key is cached
        /// </summary>
        /// <param name="key">key</param>
        /// <returns>Result</returns>
        bool IsSet(string key);

        /// <summary>
        /// Removes the value with the specified key from the cache
        /// </summary>
        /// <param name="key">/key</param>
        void Remove(string key);

        /// <summary>
        /// Removes items by pattern
        /// </summary>
        /// <param name="pattern">pattern</param>
        void RemoveByPattern(string pattern);

        /// <summary>
        /// Clear all cache data
        /// </summary>
        void Clear();
    }

继续该缓存接口类方法：

/// <summary>
    /// Represents a MemoryCacheCache
    /// </summary>
    public partial class MemoryCacheManager : ICacheManager
    {
        protected ObjectCache Cache
        {
            get
            {
                return MemoryCache.Default;
            }
        }
        
        /// <summary>
        /// Gets or sets the value associated with the specified key.
        /// </summary>
        /// <typeparam name="T">Type</typeparam>
        /// <param name="key">The key of the value to get.</param>
        /// <returns>The value associated with the specified key.</returns>
        public T Get<T>(string key)
        {
            return (T)Cache[key];
        }

        /// <summary>
        /// Adds the specified key and object to the cache.
        /// </summary>
        /// <param name="key">key</param>
        /// <param name="data">Data</param>
        /// <param name="cacheTime">Cache time</param>
        public void Set(string key, object data, int cacheTime)
        {
            if (data == null)
                return;

            var policy = new CacheItemPolicy();
            policy.AbsoluteExpiration = DateTime.Now + TimeSpan.FromMinutes(cacheTime);
            Cache.Add(new CacheItem(key, data), policy);
        }

        /// <summary>
        /// Gets a value indicating whether the value associated with the specified key is cached
        /// </summary>
        /// <param name="key">key</param>
        /// <returns>Result</returns>
        public bool IsSet(string key)
        {
            return (Cache.Contains(key));
        }

        /// <summary>
        /// Removes the value with the specified key from the cache
        /// </summary>
        /// <param name="key">/key</param>
        public void Remove(string key)
        {
            Cache.Remove(key);
        }

        /// <summary>
        /// Removes items by pattern
        /// </summary>
        /// <param name="pattern">pattern</param>
        public void RemoveByPattern(string pattern)
        {
            var regex = new Regex(pattern, RegexOptions.Singleline | RegexOptions.Compiled | RegexOptions.IgnoreCase);
            var keysToRemove = new List<String>();

            foreach (var item in Cache)
                if (regex.IsMatch(item.Key))
                    keysToRemove.Add(item.Key);

            foreach (string key in keysToRemove)
            {
                Remove(key);
            }
        }

        /// <summary>
        /// Clear all cache data
        /// </summary>
        public void Clear()
        {
            foreach (var item in Cache)
                Remove(item.Key);
        }
    }

如果上面的方法还不足够，我们可以进行方法的扩展，如：

/// <summary>
    /// Extensions
    /// </summary>
    public static class CacheExtensions
    {
        public static T Get<T>(this ICacheManager cacheManager, string key, Func<T> acquire)
        {
            return Get(cacheManager, key, 60, acquire);
        }

        public static T Get<T>(this ICacheManager cacheManager, string key, int cacheTime, Func<T> acquire) 
        {
            if (cacheManager.IsSet(key))
            {
                return cacheManager.Get<T>(key);
            }
            else
            {
                var result = acquire();
                //if (result != null)
                    cacheManager.Set(key, result, cacheTime);
                return result;
            }
        }
    }

调用的时候，就可以通过不同的KEY来区分了，调用如下：

/// <summary>
        /// 获取XX列表
        /// </summary>
        /// <param name="prjTypes"></param>
        /// <returns></returns>
        private List<xxxxPrjModel> GetxxxxProject()
        {
            var resultList = new List<xxxxPrjModel>();

            //加入5分钟缓存
            resultList = _cacheManager.Get("xxxx_PROJECTLIST", 5, () =>
            {
                return prjList.ToList();
            });
            return resultList;
        }