Question

In particular, I’m thinking of a scenario like this:

    unsafe struct Foo
    {
        public int Bar;

        public Foo* GetMyAddr()
        {
            fixed (Foo* addr = &this)
                return addr;
        }
    }

Assuming a Foo stored in unmanaged memory, I’m trying to figure out what is involved in evaluating the fixed statement in GetMyAddr. I know as the programmer that this struct is never on the managed heap, I just need to get it’s address in unmanaged memory in the most efficient manner. I’m especially concerned if there’s any locking or atomic operations used here as that would make it completely unsuitable.

Answer 1

I set up a micro benchmark and measured the overhead of fixed when used on a struct in unmanaged memory, it is very low, returning fixed(this) is only 10 times more expensive than simply returning this. That’s acceptable for my use case (hashing using the address of the struct.) I was unable to learn how it was implemented, but it does seem to be fast enough in this case.