System.Runtime.Cache立即過期

Question

我有一個網頁緩存一些查詢字符串值爲30秒，以便它不會收到重複的值。我正在使用以下類：

public class MyCache { 

private static ObjectCache cache = MemoryCache.Default; 

public MyCache() { } 


public void Insert(string key, string value) 
{ 

    CacheItemPolicy policy = new CacheItemPolicy(); 
    policy.Priority = CacheItemPriority.Default; 
    policy.SlidingExpiration = new TimeSpan(0, 0, 30); 
    policy.RemovedCallback = new CacheEntryRemovedCallback(this.Cacheremovedcallback); 

    cache.Set(key, value, policy); 
} 

public bool Exists(string key) 
{ 
    return cache.Contains(key); 
} 

public void Remove(string key) 
{ 
    cache.Remove(key); 
} 

private void Cacheremovedcallback(CacheEntryRemovedArguments arguments) 
{  
    FileLog.LogToFile("Cache item removed. Reason: " + arguments.RemovedReason.ToString() + "; Item: [" + arguments.CacheItem.Key + ", " + arguments.CacheItem.Value.ToString() + "]");   
} 
} 

這工作得很好，幾個星期後突然緩存不再保留值。 CacheRemoved回調在將項目插入緩存後立即觸發，並且我找到了刪除的原因：CacheSpecificEviction 這是在Windows Server 2008 SP1，IIS7.5與.NET 4.0上運行。在此期間沒有更改應用於操作系統或IIS。

有沒有辦法解決這個問題，如果沒有，是否有更好的緩存解決方案在網頁中使用？

預先感謝您。

Answer 1

試試這個：

policy.AbsoluteExpiration = DateTime.Now.AddSeconds(30); 

這就是我如何使用緩存：

public static class CacheHelper 
{ 
    private static ObjectCache _cache; 
    private const Double ChacheExpirationInMinutes = 10; 

    /// <summary> 
    /// Insert value into the cache using 
    /// appropriate name/value pairs 
    /// </summary> 
    /// <typeparam name="T">Type of cached item</typeparam> 
    /// <param name="entity">item cached</param> 
    /// <param name="key">Name of item</param> 
    public static void Add<T>(T entity, string key) where T : class 
    { 
     if (_cache == null) 
     { 
      _cache = MemoryCache.Default; 
     } 
     if (_cache.Contains(key)) 
      _cache.Remove(key); 
     CacheItemPolicy cacheItemPolicy = new CacheItemPolicy(); 
     cacheItemPolicy.AbsoluteExpiration = DateTime.Now.AddMinutes(ChacheExpirationInMinutes); 
     _cache.Set(key, entity, cacheItemPolicy); 
    } 

    /// <summary> 
    /// Remove item from cache 
    /// </summary> 
    /// <param name="key">Name of cached item</param> 
    public static void Clear(string key) 
    { 
     if (_cache == null) 
     { 
      _cache = MemoryCache.Default; 
      return; 
     } 
     _cache.Remove(key); 
    } 

    /// <summary> 
    /// Retrieve cached item 
    /// </summary> 
    /// <typeparam name="T">Type of cached item</typeparam> 
    /// <param name="key">Name of cached item</param> 
    /// <returns>Cached item as type</returns> 
    public static T Get<T>(string key) where T : class 
    { 
     if (_cache == null) 
     { 
      _cache = MemoryCache.Default; 
     } 
     try 
     { 
      return (T)_cache.Get(key); 
     } 
     catch 
     { 
      return null; 
     } 
    } 
}