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Comparing libev/ev.pod (file contents):
Revision 1.175 by root, Mon Sep 8 16:36:14 2008 UTC vs.
Revision 1.176 by root, Mon Sep 8 17:24:39 2008 UTC

… …
572Returns the current "event loop time", which is the time the event loop 572Returns the current "event loop time", which is the time the event loop
573received events and started processing them. This timestamp does not 573received events and started processing them. This timestamp does not
574change as long as callbacks are being processed, and this is also the base 574change as long as callbacks are being processed, and this is also the base
575time used for relative timers. You can treat it as the timestamp of the 575time used for relative timers. You can treat it as the timestamp of the
576event occurring (or more correctly, libev finding out about it). 576event occurring (or more correctly, libev finding out about it).
577
578=item ev_now_update (loop)
579
580Establishes the current time by querying the kernel, updating the time
581returned by C<ev_now ()> in the progress. This is a costly operation and
582is usually done automatically within C<ev_loop ()>.
583
584This function is rarely useful, but when some event callback runs for a
585very long time without entering the event loop, updating libev's idea of
586the current time is a good idea.
587
588See also "The special problem of time updates" in the C<ev_timer> section.
577 589
578=item ev_loop (loop, int flags) 590=item ev_loop (loop, int flags)
579 591
580Finally, this is it, the event handler. This function usually is called 592Finally, this is it, the event handler. This function usually is called
581after you initialised all your watchers and you want to start handling 593after you initialised all your watchers and you want to start handling
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1203but if multiple timers become ready during the same loop iteration then 1215but if multiple timers become ready during the same loop iteration then
1204order of execution is undefined. 1216order of execution is undefined.
1205 1217
1206=head3 The special problem of time updates 1218=head3 The special problem of time updates
1207 1219
1208Requesting the current time is a costly operation (it usually takes at 1220Establishing the current time is a costly operation (it usually takes at
1209least two syscalls): EV therefore updates it's idea of the current time 1221least two system calls): EV therefore updates its idea of the current
1210only before and after C<ev_loop> polls for new events, which causes the 1222time only before and after C<ev_loop> polls for new events, which causes
1211difference between C<ev_now ()> and C<ev_time ()>. 1223a growing difference between C<ev_now ()> and C<ev_time ()> when handling
1224lots of events.
1212 1225
1213The relative timeouts are calculated relative to the C<ev_now ()> 1226The relative timeouts are calculated relative to the C<ev_now ()>
1214time. This is usually the right thing as this timestamp refers to the time 1227time. This is usually the right thing as this timestamp refers to the time
1215of the event triggering whatever timeout you are modifying/starting. If 1228of the event triggering whatever timeout you are modifying/starting. If
1216you suspect event processing to be delayed and you I<need> to base the 1229you suspect event processing to be delayed and you I<need> to base the
1217timeout on the current time, use something like this to adjust for this: 1230timeout on the current time, use something like this to adjust for this:
1218 1231
1219 ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); 1232 ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1233
1234If the event loop is suspended for a long time, one can also force an
1235update of the time returned by C<ev_now ()> by calling C<ev_now_update
1236()>.
1220 1237
1221=head3 Watcher-Specific Functions and Data Members 1238=head3 Watcher-Specific Functions and Data Members
1222 1239
1223=over 4 1240=over 4
1224 1241

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