重新进入页面时Asp.Net缓存被清除

Question

我有一个 asp.net 函数，用作报告的数据源。当我第一次运行该函数时，我缓存了数据集，发现缓存创建成功，因为缓存计数为1。但是，当我再次进入该函数时，我无法获取缓存内容。并且缓存计数为零。似乎由于某种原因缓存被清除了。如何找出重新进入页面时缓存计数为零的原因以及如何使缓存发挥作用？这是我的代码：

//using System.Web.Caching;

using System.Runtime.Caching;

namespace Sustainability.BusinessObject.Client

{

    public class ReportManager

    {

        protected static MemoryCache CACHE = new MemoryCache("MySQLDataProvider_Cache");

        public static DataSet KPISummaryReport(int companyID, int fromYear, int fromMonth, int toYear, int toMonth, string locationIDs, bool hideIfNoValue, string lang)

        {

            HttpResponseMessage result = null;            

            DataSet ds = null; 

            try

            {

                string cacheKey = "kpi_" + companyID + "_" + fromYear + "_" + fromMonth + "_" + toYear + "_" + toMonth + "_" + locationIDs;

                Logger.Log(string.Format("Cache count of reentering the code {0}", CACHE.GetCount()));

                ds = CACHE.Get(cacheKey) as DataSet;

                if (ds != null)

                {

                    return ds;

                }

                else

                {

                    ds = Util.GetData(_sustainabilityServiceURL, requestUri, out result);

                    var policy = new CacheItemPolicy { AbsoluteExpiration = DateTime.Now.AddMinutes(60d) };

                    CACHE.Add(cacheKey, ds, policy);

                    DataSet ds1 = CACHE.Get(cacheKey) as DataSet;

                    if (ds1 != null)

                    {

                        Logger.Log("Create Cache Succesfully");

                    }

                    else

                    {

                        Logger.Log("Create Cache Failed");

                    }

                    Logger.Log(string.Format("Cache count after create cache {0}",CACHE.GetCount()));

                }

         }

   }

Answer 1

检查您用于缓存的数据库，我的第一个猜测是实际上没有存储任何内容。使用 IoC，正确的设置看起来像是向服务添加分布式缓存services.AddDistributedSqlServerCache(options =>{    options.ConnectionString = _config["SQLDataProvider_Cache"];    options.SchemaName = "dbo";    options.TableName = "TestCache";});您可以使用两种类型的缓存策略：(DateTimeOffSet) CacheItemPolicy.AbsoluteExpiration 在初始设置的固定时间后过期(DateTimeOffSet) CacheItemPolicy.SlidingExpiration 自上次访问起的固定时间后过期通常您会想要使用 SlidingExpiration 之一，但当您定义绝对时，注册将public void Configure(IApplicationBuilder app, IHostingEnvironment env,     IApplicationLifetime lifetime, IDistributedCache cache){    lifetime.ApplicationStarted.Register(() =>    {        var currentTimeUTC = DateTime.UtcNow.ToString();        var encodedCurrentTimeUTC = Encoding.UTF8.GetBytes(currentTimeUTC);        var options = new DistributedCacheEntryOptions()            .SetAbsoluteExpiration(TimeSpan.FromHours(1));        cache.Set("cachedTimeUTC", encodedCurrentTimeUTC, options);    });存储库本身不应包含静态成员（或仅包含记录器）。为该存储库添加接口将改进测试和模拟功能，并且成为使用 IoC 传递此信息的默认方式public class ReportRepository : IReportRepository{    private readonly IAppCache _cache;    private readonly ILogger _logger;    private SomeService _service;    public string ServiceUrl { get; set; }    public string RequestUri { get; set; }     public ReportRepository(IAppCache appCache, ILogger<ShowDatabase> logger, SomeService service)    {        _service = service;        _logger = logger;        _cache = appCache;    }     public async Task<List<Show>> GetShows()    {            var cacheKey = "kpi_{companyID}_{fromYear}_{fromMonth}_{toYear}_{toMonth}_{locationIDs}";        Func<Task<List<DataSet>>> reportFactory = () => PopulateReportCache();        //if you do it in DistributedCacheEntryOptions you do not need to set it here        var absoluteExpiration = DateTimeOffset.Now.AddHours(1);        var result = await _cache.GetOrAddAsync(cacheKey, reportFactory, absoluteExpiration);        return result;    }      private async Task<List<DataSet>> PopulateReportCache()    {        List<DataSet> reports = await _service.GetData(ServiceUrl, RequestUri, out result);        _logger.LogInformation($"Loaded {reports.Count} report(s)");        return reports.ToList(); //I would have guessed it returns out parameter result ...    }}