=head1 GLOBAL FUNCTIONS
+These functions can be called anytime, even before initialising the
+library in any way.
+
=over 4
=item ev_tstamp ev_time ()
reschedule callback will be called with the watcher as first, and the
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 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.
+NOTE: I<This callback MUST NOT stop or destroy any 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 (e.g. by
+starting a prepare watcher).
Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
ev_tstamp now)>, e.g.:
will usually be called just before the callback will be triggered, but
might be called at other times, too.
+NOTE: I<< This callback must always return a time that is later than the
+passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.
+
This can be used to create very complex timers, such as a timer that
triggers on each midnight, local time. To do this, you would calculate the
-next midnight after C<now> and return the timestamp value for this. How you do this
-is, again, up to you (but it is not trivial).
+next midnight after C<now> and return the timestamp value for this. How
+you do this is, again, up to you (but it is not trivial, which is the main
+reason I omitted it as an example).
=back
=head2 C<ev_prepare> and C<ev_check> - customise your event loop
Prepare and check watchers are usually (but not always) used in tandem:
-Prepare watchers get invoked before the process blocks and check watchers
+prepare watchers get invoked before the process blocks and check watchers
afterwards.
Their main purpose is to integrate other event mechanisms into libev. This
provide just this functionality). Then, in the check watcher you check for
any events that occured (by checking the pending status of all watchers
and stopping them) and call back into the library. The I/O and timer
-callbacks will never actually be called (but must be valid neverthelles,
+callbacks will never actually be called (but must be valid nevertheless,
because you never know, you know?).
As another example, the Perl Coro module uses these hooks to integrate
coroutines into libev programs, by yielding to other active coroutines
during each prepare and only letting the process block if no coroutines
-are ready to run (its actually more complicated, it only runs coroutines
-with priority higher than the event loop and one lower priority once,
-using idle watchers to keep the event loop from blocking if lower-priority
-coroutines exist, thus mapping low-priority coroutines to idle/background
-tasks).
+are ready to run (it's actually more complicated: it only runs coroutines
+with priority higher than or equal to the event loop and one coroutine
+of lower priority, but only once, using idle watchers to keep the event
+loop from blocking if lower-priority coroutines are active, thus mapping
+low-priority coroutines to idle/background tasks).
=over 4
=back
+=head1 LIBEVENT EMULATION
+
+TBD.
+
+=head1 C++ SUPPORT
+
+TBD.
+
=head1 AUTHOR
Marc Lehmann <libev@schmorp.de>.
projects / software / libev.git / blobdiff