From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2008-05-30 13:23:43
-----BEGIN PGP SIGNED MESSAGE-----
On Friday 30 May 2008 11:45 am, Anthony Williams wrote:
> > One problem is wait_for_any is not sufficient to implement an efficient
> > scheduler. You have to copy all the futures into wait_for_any so each
> > wait_for_any call is O(N). So something like the future_selecter (should
> > be spelled future_selector?) class I mentioned earlier would still be
> > needed.
> What do you mean by O(N) in this context?
I mean there are N method requests in my scheduler, and I want to wait until
one of them is ready.
> You have N futures to wait for. You have to somehow register that
> you're waiting for each one => you need O(N) operations.
Yes. But the scheduler is going to repeatedly wait on the same N futures
(plus or minus one). So as Johan already pointed out, passing iterators to a
seperate container of futures to wait_for_any() will cause the sheduler to
call wait_for_any N times and take O(N^2) to dispatch N method requests. On
the other hand, if the container of futures and wait_for_any are integrated
into one class (future_selector), then it doesn't have to do the full
setup/tear down with each wait.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)
-----END PGP SIGNATURE-----
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk