public void ClearCache(string pattern, DateTime since)
{
Regex regex = new Regex(pattern);
foreach (var k in cache.Where(i => regex.IsMatch(i.Key))) {
var cacheItem = cache.GetCacheItem(k.Key);
IOpenSearchResponse response = (IOpenSearchResponse)cacheItem.Value;
if ( response.Created < since )
cache.Remove(k.Key);
}
}