C# multithreading

Question

Can ICollection<T>.Count property getter be considered atomic (and, therefore, threadsafe)?

Thank you.

Answer 1

It completely depends on the collection; ICollection<T> is just an interface.

Every collection that I know of simply returns an Int32 field in its Count getter, so it usually is atomic.
However, there is never a guarantee that the count didn't change just after you fetched the property.

Answer 2

No, as you can only make that assumption for implementations, not an interface.