WingCloudServer/Tools/GeneralDocTool/Helper/CommonMemoryCaching.cs

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

namespace WingCloudServer.GeneralDocTools.Helper
{
    public class CommonMemoryCaching
    {
        private static readonly object SynObject = new object();
        private static CommonMemoryCaching instance = null;

        private CommonMemoryCaching()
        {
            Task.Run(async () =>
            {
                while (true)
                {
                    List<string> list = new List<string>();
                    foreach (var item in this._myCacheExpire.Keys)
                    {
                        this._myCacheExpire.TryGetValue(item, out var expireObj);
                        if (expireObj != null)
                        {
                            if (expireObj.Item1 < expireObj.Item2)
                            {
                                list.Add(item);
                            }
                        }
                    }
                    foreach (var item in list)
                    {
                        this._myCacheExpire.TryRemove(item, out var expireObj);
                        this._myCache.TryRemove(item, out var cacheObj);
                    }
                    await Task.Delay(500);
                }
            });
        }

        /// <summary>
        /// 单例模式
        /// </summary>
        public static CommonMemoryCaching GetInstance()
        {
            if (instance == null)
            {
                lock (SynObject)
                {
                    if (instance == null)
                    {
                        instance = new CommonMemoryCaching();
                    }
                }
            }
            return instance;
        }

        private readonly ConcurrentDictionary<string, object> _myCache = new ConcurrentDictionary<string, object>();
        private readonly ConcurrentDictionary<string, Tuple<DateTime, DateTime>> _myCacheExpire = new ConcurrentDictionary<string, Tuple<DateTime, DateTime>>();
        private const long DefaultExpireTime = 300000;

        /// <summary>
        /// 获取和设置缓存信息
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="cacheItemName"></param>
        /// <param name="objectSettingFunction"></param>
        /// <param name="expireTime">默认过期时间5分钟</param>
        /// <returns></returns>
        public T GetOrSetObjectFromCache<T>(string cacheItemName, Func<T> objectSettingFunction, bool isSetExpire = true, long expireTime = DefaultExpireTime)
        {
            T cacheObject = default(T);

            this._myCache.TryGetValue(cacheItemName, out var cacheObj);
            if (cacheObj != null)
            {
                cacheObject = (T)cacheObj;
            }
            else
            {
                if (objectSettingFunction != null)
                {
                    cacheObject = objectSettingFunction();
                    this._myCache.TryAdd(cacheItemName, cacheObject);
                    if (isSetExpire)
                    {
                        Tuple<DateTime, DateTime> tuple = Tuple.Create<DateTime, DateTime>(DateTime.Now, DateTime.Now.AddMilliseconds(expireTime));
                        this._myCacheExpire.TryAdd(cacheItemName, tuple);
                    }
                }
            }
            return cacheObject;
        }

        /// <summary>
        /// 设置缓存
        /// </summary>
        /// <param name="key"></param>
        /// <param name="value"></param>
        /// <param name="cacheTimeInMinutes"></param>
        public void SetValueToCache(string key, object value, bool isSetExpire = true, long expireTime = DefaultExpireTime)
        {
            if (Contains(key))
            {
                Remove(key);
            }
            this._myCache.TryAdd(key, value);
            if (isSetExpire)
            {
                Tuple<DateTime, DateTime> tuple = Tuple.Create<DateTime, DateTime>(DateTime.Now, DateTime.Now.AddMilliseconds(expireTime));
                this._myCacheExpire.TryAdd(key, tuple);
            }
        }

        /// <summary>
        /// 获取缓存
        /// </summary>
        /// <param name="key"></param>
        /// <returns></returns>
        public object GetValueFromCache(string key)
        {
            if (Contains(key))
            {
                this._myCache.TryGetValue(key, out var cacheObj);
                return cacheObj;
            }
            else
            {
                return null;
            }
        }

        /// <summary>
        /// 验证缓存是否存在
        /// </summary>
        /// <param name="key"></param>
        /// <returns></returns>
        public bool Contains(string key)
        {
            return this._myCache.ContainsKey(key);
        }

        /// <summary>
        /// 删除制定缓存
        /// </summary>
        /// <param name="key"></param>
        public void Remove(string key)
        {
            this._myCache.TryRemove(key, out var cacheObj);
            this._myCacheExpire.TryRemove(key, out var expireObj);
        }

        /// <summary>
        /// 移除所有缓存
        /// </summary>
        public void RemoveAll()
        {
            this._myCache.Clear();
            this._myCacheExpire.Clear();
        }

    }
}