Returns the current time as libev would use it.
+Returns the current time as libev would use it. Please note that the
+ev_now function is usually faster and also often returns the timestamp
+you actually want to know.
This flags value could be used to implement alternative looping
constructs, but the prepare and check watchers provide a better and
more generic mechanism.
Here are the gory details of what ev_loop does:
+1. If there are no active watchers (reference count is zero), return. + 2. Queue and immediately call all prepare watchers. + 3. If we have been forked, recreate the kernel state. + 4. Update the kernel state with all outstanding changes. + 5. Update the "event loop time". + 6. Calculate for how long to block. + 7. Block the process, waiting for events. + 8. Update the "event loop time" and do time jump handling. + 9. Queue all outstanding timers. + 10. Queue all outstanding periodics. + 11. If no events are pending now, queue all idle watchers. + 12. Queue all check watchers. + 13. Call all queued watchers in reverse order (i.e. check watchers first). + 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK + was used, return, otherwise continue with step #1. + +
The timers are based on real time, that is, if you register an event that times out after an hour and you reset your system clock to last years time, it will still time out after (roughly) and hour. "Roughly" because -detecting time jumps is hard, and soem inaccuracies are unavoidable (the +detecting time jumps is hard, and some inaccuracies are unavoidable (the monotonic clock option helps a lot here).
The relative timeouts are calculated relative to the ev_now ()
time. This is usually the right thing as this timestamp refers to the time
-of the event triggering whatever timeout you are modifying/starting. If
-you suspect event processing to be delayed and you *need* to base the timeout
+of the event triggering whatever timeout you are modifying/starting. If
+you suspect event processing to be delayed and you need to base the timeout
on the current time, use something like this to adjust for this:
ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);+
The callback is guarenteed to be invoked only when its timeout has passed, +but if multiple timers become ready during the same loop iteration then +order of execution is undefined.
They can also be used to implement vastly more complex timers, such as triggering an event on eahc midnight, local time.
+As with timers, the callback is guarenteed to be invoked only when the
+time (at) has been passed, but if multiple periodic timers become ready
+during the same loop iteration then order of execution is undefined.
Lots of arguments, lets sort it out... There are basically three modes of operation, and we will explain them from simplest to complex:
- - - -