internal static void OnCacheEntryRemovedCallback(CacheEntryRemovedArguments arguments)
{
MemoryCache cache = arguments.Source as MemoryCache;
SentinelEntry entry = arguments.CacheItem.Value as SentinelEntry;
CacheEntryRemovedReason reason = arguments.RemovedReason;
switch (reason)
{
case CacheEntryRemovedReason.Expired:
break;
case CacheEntryRemovedReason.ChangeMonitorChanged:
if (entry.ExpensiveObjectDependency.HasChanged)
{
// If the expensiveObject has been removed explicitly by Cache.Remove,
// return from the SentinelEntry removed callback
// thus effectively removing the SentinelEntry from the cache.
return;
}
break;
case CacheEntryRemovedReason.Evicted:
Dbg.Fail("Reason should never be CacheEntryRemovedReason.Evicted since the entry was inserted as NotRemovable.");
return;
default:
// do nothing if reason is Removed or CacheSpecificEviction
return;
}
// invoke update callback
try
{
CacheEntryUpdateArguments args = new CacheEntryUpdateArguments(cache, reason, entry.Key, null);
entry.CacheEntryUpdateCallback(args);
Object expensiveObject = (args.UpdatedCacheItem != null) ? args.UpdatedCacheItem.Value : null;
CacheItemPolicy policy = args.UpdatedCacheItemPolicy;
// Only update the "expensive" object if the user returns a new object,
// a policy with update callback, and the change monitors haven't changed. (Inserting
// with change monitors that have already changed will cause recursion.)
if (expensiveObject != null && IsPolicyValid(policy))
{
cache.Set(entry.Key, expensiveObject, policy);
}
else
{
cache.Remove(entry.Key);
}
}
catch
{
cache.Remove(entry.Key);
// Review: What should we do with this exception?
}
}
