c# - 自己更新メモリキャッシュ

Question

有効期限が切れたときに含まれている値を更新するキャッシュを実装しました。

私のコードはこれです：

class MyCache
{
    private static readonly MemoryCache Cache = MemoryCache.Default;

    private CacheItemPolicy _errorpolicy;
    private CacheItemPolicy _warnPolicy;

    private CacheEntryRemovedCallback _warnCacheEntryRemovedCallback;
    private CacheEntryRemovedCallback _errorCacheEntryRemovedCallback;

    public void AddErrors(string key, object errors)
    {
        _errorCacheEntryRemovedCallback = ErrorItemRemovedCallback;
        _errorpolicy = new CacheItemPolicy
        {
            AbsoluteExpiration = DateTimeOffset.Now.AddSeconds(7.00),
            RemovedCallback = _errorCacheEntryRemovedCallback
        };

        Cache.Set(key, errors, _errorpolicy);
    }

    public void AddWarnings(string key, object warnings)
    {
        _warnCacheEntryRemovedCallback = WarningCacheItemRemovedCallback;
        _warnPolicy = new CacheItemPolicy
        {
            AbsoluteExpiration = DateTimeOffset.Now.AddSeconds(4.00),
            RemovedCallback = _warnCacheEntryRemovedCallback
        };

        Cache.Set(key, warnings, _warnPolicy);
    }

    private void ErrorItemRemovedCallback(CacheEntryRemovedArguments arguments)
    {
        Console.WriteLine("{0} Item removed: {1}", DateTime.UtcNow, arguments.CacheItem.Key);
        Cache.Set(arguments.CacheItem.Key, new List<string> { "error1", "error2", "error3" }, _errorpolicy);

    }

    private void WarningCacheItemRemovedCallback(CacheEntryRemovedArguments arguments)
    {
        Console.WriteLine("{0} Item removed: {1}", DateTime.UtcNow, arguments.CacheItem.Key);
        Cache.Set(arguments.CacheItem.Key, new List<string> { "warn1", "warn2", "warn3" }, _warnPolicy);
    }
}

しかし、何かが間違っています。

上記はプロンプトにこれを書き込みます：

04-05-2014 21:20:00 Item removed: warn
04-05-2014 21:20:00 Item removed: error
04-05-2014 21:20:20 Item removed: error
04-05-2014 21:20:20 Item removed: warn
04-05-2014 21:20:40 Item removed: warn
04-05-2014 21:20:40 Item removed: error
04-05-2014 21:20:40 Item removed: error
04-05-2014 21:20:40 Item removed: warn

...そして、私は次のようなことを期待していたでしょう

04-05-2014 21:20:04 Item removed: warn
04-05-2014 21:20:07 Item removed: error
04-05-2014 21:20:08 Item removed: warn
04-05-2014 21:20:12 Item removed: warn
04-05-2014 21:20:14 Item removed: error
...

私は何が欠けていますか？

2014 年 5 月 14 日更新:

フィールドレベル変数をローカル変数に変更しましたが、同じ動作が存在します。また、キャッシュからの削除の順序が変更されていることにも注意してください。最初は「エラー後警告」ですが、次は「警告後エラー」です。

また、キャッシュからの最初の削除は 21 秒後に行われることに注意してください。この後は、20 秒ごとに常に発生します。

14-05-2014 13:00:59 Adding errors to cache
14-05-2014 13:00:59 Adding warnings to cache
Press 'q' to quit
14-05-2014 13:01:20 Item removed: warn
14-05-2014 13:01:20 Item removed: error
14-05-2014 13:01:40 Item removed: error
14-05-2014 13:01:40 Item removed: warn
14-05-2014 13:02:00 Item removed: warn
14-05-2014 13:02:00 Item removed: error
14-05-2014 13:02:20 Item removed: error
14-05-2014 13:02:20 Item removed: warn
14-05-2014 13:02:40 Item removed: warn
14-05-2014 13:02:40 Item removed: error

私の全体（新しいコード）はここにあります：

namespace DemoCache
{
    internal class Program
    {
        private static readonly List<string> ErrorList = new List<string> {"error1", "error2", "error3"};
        private static readonly List<string> WarningList = new List<string> {"warn1", "warn2", "warn3"};

        static void Main()
        {
            var myCache = new MyCache();

            Console.WriteLine("{0} Adding errors to cache ", DateTime.UtcNow);
            myCache.AddErrors("error", ErrorList);
            Console.WriteLine("{0} Adding warnings to cache", DateTime.UtcNow);
            myCache.AddWarnings("warn", WarningList);

            Console.WriteLine("Press 'q' to quit");

            var keepRunning = true;
            do
            {
                var key = Console.ReadKey(true);

                switch (Char.ToLower(key.KeyChar))
                {
                    case 'q':
                        keepRunning = false;
                        break;
                }
            } while (keepRunning);
        }
    }

    class MyCache
    {
        private static readonly MemoryCache Cache = new MemoryCache("name");

        //private CacheItemPolicy _errorpolicy;
        //private CacheItemPolicy _warnPolicy;

        //private CacheEntryRemovedCallback _warnCacheEntryRemovedCallback;
        //private CacheEntryRemovedCallback _errorCacheEntryRemovedCallback;

        public void AddErrors(string key, object errors)
        {
            CacheEntryRemovedCallback errorCacheEntryRemovedCallback = ErrorItemRemovedCallback;
            var errorpolicy = new CacheItemPolicy
            {
                AbsoluteExpiration = DateTime.Now.AddSeconds(7.00),
                RemovedCallback = errorCacheEntryRemovedCallback
            };

            Cache.Set(key, errors, errorpolicy);
        }

        public void AddWarnings(string key, object warnings)
        {
            CacheEntryRemovedCallback warnCacheEntryRemovedCallback = WarningCacheItemRemovedCallback;
            var warnPolicy = new CacheItemPolicy
            {
                AbsoluteExpiration = DateTime.Now.AddSeconds(11.00),
                RemovedCallback = warnCacheEntryRemovedCallback
            };

            Cache.Set(key, warnings, warnPolicy);
        }

        private void ErrorItemRemovedCallback(CacheEntryRemovedArguments arguments)
        {
            Console.WriteLine("{0} Item removed: {1}", DateTime.UtcNow, arguments.CacheItem.Key);
            AddErrors(arguments.CacheItem.Key, new List<string> { "error1", "error2", "error3" });
            //Cache.Set(arguments.CacheItem.Key, , _errorpolicy);

        }

        private void WarningCacheItemRemovedCallback(CacheEntryRemovedArguments arguments)
        {
            Console.WriteLine("{0} Item removed: {1}", DateTime.UtcNow, arguments.CacheItem.Key);
            AddWarnings(arguments.CacheItem.Key, new List<string> { "warn1", "warn2", "warn3" });
            //Cache.Set(arguments.CacheItem.Key, new List<string> { "warn1", "warn2", "warn3" }, _warnPolicy);
        }
    }
}