Each "poller" registers a non-blocking callback which is then called in
every iteration of a reactor's main loop.
Each "poller"'s callback returns a boolean: if TRUE then a main loop is allowed to block
(e.g. in epoll()).
If any of registered "pollers" returns FALSE then reactor's main loop is forbidded to block
in the current iteration.
Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
47b3721ccf