c# - 在 Azure 上刷新 HttpRuntime.Cache

Question

有没有一种方法可以在 Azure 上刷新 HttpRuntime.Cache 而无需重新启动实例？

谢谢

Answer 1

当您将项目添加到缓存时，您应该使用带有全局键的CacheDependency添加它们。这使您可以让您的项目在给定时间后过期，但也可以清除与此密钥链接的所有项目。

这是清除所有项目（ CacheProvider.cs）的方法的示例实现：

/// <summary>
/// Caching provider
/// </summary>
public static class CacheProvider
{
    const string CacheDependencyKey = "1FADE275-2C84-4a9b-B3E1-68ABB15E53C8";
    static readonly object SyncRoot = new object();

    /// <summary>
    /// Gets an item from cache. If the item does not exist, one will be
    /// created and added to the cache.
    /// </summary>
    /// <param name="key">Caching key</param>
    /// <param name="valueFactory">Function to create the item of it does not exist in the cache.</param>
    /// <param name="expiresAfter">Time after the item wille be removed from cache.</param>
    public static TValue GetOrAdd<TValue>(string key, Func<TValue> valueFactory, TimeSpan expiresAfter)
    {
        object itemFromCache = HttpRuntime.Cache.Get(key);
        if (itemFromCache == null)
        {
            lock (SyncRoot)
            {
                itemFromCache = HttpRuntime.Cache.Get(key);
                if (itemFromCache == null)
                {
                    TValue value = valueFactory();
                    if (value != null)
                    {
                        if (HttpRuntime.Cache[CacheDependencyKey] == null)
                            HttpRuntime.Cache[CacheDependencyKey] = string.Empty;

                        HttpRuntime.Cache.Add(key, value, new CacheDependency(null, new string[] { CacheDependencyKey }), DateTime.Now.Add(expiresAfter), Cache.NoSlidingExpiration, CacheItemPriority.Normal, null);
                    }
                    return value;
                }
            }
        }
        return (TValue)itemFromCache;
    }

    /// <summary>
    /// Invalidate all the items from the cache.
    /// </summary>
    public static void InvalidateCache()
    {
        HttpRuntime.Cache.Remove(CacheDependencyKey);
    }
}

Answer 2

public void Clear()
{
   var itemsToRemove = new List<string>();

   var enumerator = HttpContext.Current.Cache.GetEnumerator();
   while (enumerator.MoveNext())
   {
      itemsToRemove.Add(enumerator.Key.ToString());
   }

   foreach (string itemToRemove in itemsToRemove)
   {
      HttpContext.Current.Cache.Remove(itemToRemove);
   }
}