Question

我有一个包含以下属性的类：

public Dictionary<string, int> CommentCounts {
    get {
        string cacheKey = "CommentCounts";
        HttpContext c = HttpContext.Current;

        if (c.Cache[cacheKey] == null) {
            c.Cache.Insert(cacheKey, new Dictionary<string, int>(), null, DateTime.UtcNow.AddSeconds(30), System.Web.Caching.Cache.NoSlidingExpiration, CacheItemPriority.High, null);
            c.Trace.Warn("New cached item: " + cacheKey); 
        }

        return (Dictionary<string, int>)c.Cache[cacheKey];
    }
    set {
        HttpContext.Current.Cache["CommentCounts"] = value;
    }
}

似乎Trace语句只运行一次，而不是在Cache项目到期后每30秒运行一次。我可以让它刷新缓存项的唯一方法是创建代码机会并重建项目，这显然不太理想。

我错过了什么？提前谢谢......

Answer 1

该属性的set部分可能是原因 - Cache["key"] = value相当于使用Cache.Insert调用NoAbsoluteExpiration, NoSlidingExpiration，这意味着它永不过期。正确的解决方案如下所示：

public Dictionary<string, int> CommentCounts {
    get {
        const string cacheKey = "CommentCounts";
        HttpContext c = HttpContext.Current;

        if (c.Cache[cacheKey] == null) CommentCounts = new Dictionary<string, int>();

        return (Dictionary<string, int>)c.Cache[cacheKey];
    }
    set {
        const string cacheKey = "CommentCounts";
        c.Cache.Insert(cacheKey, value, null, DateTime.UtcNow.AddSeconds(30), System.Web.Caching.Cache.NoSlidingExpiration, CacheItemPriority.High, null);
        c.Trace.Warn("New cached item: " + cacheKey); 
    }
}

Answer 2

我之前遇到过这个问题asked a question here;它从来没有真正回答过，但答案中可能会有一些有用的调试技巧。

缓存项目永不过期

2 个答案: