[boost] Re: Intrusive/invasive smart pointer?

From: Andy Glew (glew_at_[hidden])
Date: 2000-01-13 01:13:52

> That doesn't force us to have an intrusive reference-count (unless I
> misunderstand the meaning of "not available"). What it forces is some way of
> getting to the count for existing objects which are already being counted.
> You could store that association in a hash table.
> 
> I have already been in communication with Greg about that possibility,
> because twice colleagues of mine have made the mistake of initializing a
> smart_ptr with a raw pointer to an object which is already being counted.
> One of the engineers was senior.

You can make the association with a hash table,
but intrusiveness is one hell of a lot less expensive
than hashing.

(Although... I'm the "MLP", Memory Level Parallelism, guy.
In the MLP world, computation is free, cache missing memory
accesses are all that cost, and parallel cache misses are okay.
In that MLP world, the hash access isn't so bad, as long as
there are no collision chains, no extra levels of indirection, 
etc.  But, the hardware we program on will not be in that
world for 8 years, if ever.)