Re: Rethinking stats communication mechanisms

>
> > BTW, I think the writer would actually need to bump the
> counter twice,
> > once before and once after it modifies its stats area.
> Else there's
> > no way to detect that you've copied a partially-updated stats entry.
>
> Actually, neither of these ideas works: it's possible that
> the reader copies the entry between the two increments of the
> counter. Then, it won't see any reason to re-read, but
> nonetheless it has copied an inconsistent partially-modified entry.
>
> Anyone know a variant of this that really works?
>

Here's a theory: If the counter is bumped to an odd number before
modification, and an even number after it's done, then the reader will
know it needs to re-read if the counter is an odd number.

This might be assuming too much about what the writer knows about the
current contents of the counter, but since it's per-back end, I think it
would work.

Regards,
Paul Bort