>
> * reader's read starts before and ends after writer's update: reader
> will certainly note a change in update counter.
>
> * reader's read starts before and ends within writer's update: reader
> will note a change in update counter.
>
> * reader's read starts within and ends after writer's update: reader
> will note a change in update counter.
>
> * reader's read starts within and ends within writer's update: reader
> will see update counter as odd.
>
> Am I missing anything?
>
The only remaining concern would be the possibility of the reader
thrashing because the writer is updating so often that the reader never
gets the same counter twice. IIRC, the reader was only sampling, not
trying to catch every entry, so that will help. But is it enough?
Regards,
Paul Bort