/// <summary>
/// Gets a <c>CacheItem</c> for the specified key.
/// </summary>
/// <param name="key">The key being used to identify the item within the cache.</param>
/// <param name="region">The cache region.</param>
/// <returns>The <c>CacheItem</c>.</returns>
protected override CacheItem <TCacheValue> GetCacheItemInternal(string key, string region)
{
CacheItem <TCacheValue> item = null;
if (_serializer != null)
{
// If it's expired, this result could be null, so we just set Item to null
var cacheItemBytes = _cache.Get(key, region);
if (cacheItemBytes != null)
{
item = _serializer.DeserializeCacheItem <TCacheValue>((byte[])cacheItemBytes, typeof(TCacheValue));
}
}
else
{
item = (CacheItem <TCacheValue>)_cache.Get(key, region);
}
if (item == null)
{
return(null);
}
// maybe the item is already expired because FileCache implements a default interval
// of 20 seconds! to check for expired items on each store, we do it on access to also
// reflect smaller time frames especially for sliding expiration...
// cache.Get eventually triggers eviction callback, but just in case...
if (item.IsExpired)
{
RemoveInternal(item.Key, item.Region);
TriggerCacheSpecificRemove(item.Key, item.Region, CacheItemRemovedReason.Expired, item.Value);
return(null);
}
if (item.ExpirationMode == ExpirationMode.Sliding)
{
// because we don't use UpdateCallback because of some multithreading issues lets
// try to simply reset the item by setting it again.
// item = this.GetItemExpiration(item); // done via base cache handle
if (_serializer != null)
{
_cache.Set(key, _serializer.SerializeCacheItem(item), GetPolicy(item), region);
}
else
{
_cache.Set(key, item, GetPolicy(item), region);
}
}
return(item);
}
protected override object DeserializeObject(ArraySegment <byte> value)
{
var position = value.Offset;
var typeNameLen = BitConverter.ToUInt16(value.Array, position);
position += 2;
var typeName = Encoding.UTF8.GetString(value.Array, position, typeNameLen);
position += typeNameLen;
if (value.Array[position++] != 0)
{
throw new InvalidOperationException("Invalid data, stop bit not found in type name encoding.");
}
var data = new byte[value.Count - position + value.Offset];
Buffer.BlockCopy(value.Array, position, data, 0, data.Length);
return(_serializer.DeserializeCacheItem <T>(data, TypeCache.GetType(typeName)));
}
protected override CacheItem <TCacheValue> GetCacheItemInternal(string key, string region)
{
var fullKey = GetKey(key, region);
CacheItem <TCacheValue> deserializedResult = null;
if (_cache.TryGetValue(fullKey, out Tuple <Type, byte[]> result))
{
deserializedResult = _serializer.DeserializeCacheItem <TCacheValue>(result.Item2, result.Item1);
if (deserializedResult.ExpirationMode != ExpirationMode.None && IsExpired(deserializedResult, DateTime.UtcNow))
{
_cache.TryRemove(fullKey, out Tuple <Type, byte[]> removeResult);
TriggerCacheSpecificRemove(key, region, CacheItemRemovedReason.Expired, deserializedResult.Value);
return(null);
}
}
return(deserializedResult);
}
