Question

For a remoting framework, I need to keep some metadata about object that I’m returning.
I have no control over the object themselves (so I can’t make them IDisposable), I also don’t know their type. my only assumption is that it’s a reference type.

The problem is life time, when do I free my metadata.

I intend to create a static dictionary(ConcurrentDictionary) and hold there a WeakReference to the object, and the metadata. The question is, how do i know when to delete the metadata?
is there a way to receive a notification when the object itself is finalized?

Also i don’t care about necromancy (object resurrection)

Thank you

Answer 1

If you’re using .NET4 or later you could possibly use ConditionalWeakTable<K,V>.

This would mean that you (probably) wouldn’t need to worry about freeing-up the metadata yourself: it would just disappear from the table once the object itself was gone.

The ConditionalWeakTable<TKey, TValue> class differs from other
collection objects in its management of the object lifetime of keys
stored in the collection. Ordinarily, when an object is stored in a
collection, its lifetime lasts until it is removed (and there are no
additional references to the object) or until the collection object
itself is destroyed. However, in the ConditionalWeakTable<TKey,
TValue> class, adding a key/value pair to the table does not ensure
that the key will persist, even if it can be reached directly from a
value stored in the table (for example, if the table contains one key,
A, with a value V1, and a second key, B, with a value P2 that contains
a reference to A). Instead, ConditionalWeakTable<TKey, TValue>
automatically removes the key/value entry as soon as no other
references to a key exist outside the table.