/// <summary>
/// Tries to insert a cache entry into the cache as a <see cref="T:System.Runtime.Caching.CacheItem" /> instance,
/// and adds details about how the entry should be evicted.
/// </summary>
/// <returns>
/// true if insertion succeeded, or false if there is an already an entry in the cache that has the same key as
/// <paramref name="item" />.
/// </returns>
/// <param name="item">The object to add.</param>
/// <param name="policy">
/// An object that contains eviction details for the cache entry. This object provides more options
/// for eviction than a simple absolute expiration.
/// </param>
public override bool Add(CacheItem item, CacheItemPolicy policy)
{
if (item == null)
{
throw new ArgumentNullException(nameof(item));
}
if (policy == null)
{
throw new ArgumentNullException(nameof(policy));
}
var cacheRegion = this.AddOrGetExistingCacheRegion(item);
if (cacheRegion.ContainsKey(item.Key))
{
return(false);
}
var entryItem = new CacheEntryItem(item, policy);
cacheRegion.Add(item.Key, entryItem);
this.ValidatePolicy(entryItem);
return(true);
}
private void ValidatePolicy(CacheEntryItem item)
{
if (DateTime.Now - item.LastAccessed < item.SlidingExpiration &&
item.Expiration.Ticks - DateTime.Now.Ticks > 0)
{
item.LastAccessed = DateTime.Now;
return;
}
item.EntryRemovedCallback(
new CacheEntryRemovedArguments(this, CacheEntryRemovedReason.Expired, item.ToCacheItem()));
this.InternalCache[item.RegionName].Remove(item.Key);
}