This section describes each watcher in detail, but will not repeat
information given in the last section.
-=head2 C<ev_io> - is my file descriptor readable or writable
+=head2 C<ev_io> - is this file descriptor readable or writable
I/O watchers check whether a file descriptor is readable or writable
in each iteration of the event loop (This behaviour is called
This doesn't mean there will always be 3600 seconds in between triggers,
but only that the the callback will be called when the system time shows a
-full hour (UTC), or more correct, when the system time is evenly divisible
+full hour (UTC), or more correctly, when the system time is evenly divisible
by 3600.
Another way to think about it (for the mathematically inclined) is that
current time as second argument.
NOTE: I<This callback MUST NOT stop or destroy the periodic or any other
-periodic watcher, ever, or make any event loop modificstions>. If you need
-to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards.
+periodic watcher, ever, or make any event loop modifications>. If you need
+to stop it, return C<now + 1e30> (or so, fudge fudge) and stop it afterwards.
+
+Also, I<<this callback must always return a time that is later than the
+passed C<now> value >>. Not even C<now> itself will be ok.
Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
ev_tstamp now)>, e.g.: