[ViewVC] Diff of: cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.305 by root, Thu Oct 14 05:07:04 2010 UTC vs.
Revision 1.317 by root, Fri Oct 22 09:35:06 2010 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
124	this argument.	124	this argument.
125		125
126	=head2 TIME REPRESENTATION	126	=head2 TIME REPRESENTATION
127		127
128	Libev represents time as a single floating point number, representing	128	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (in practise	129	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	somewhere near the beginning of 1970, details are complicated, don't	130	somewhere near the beginning of 1970, details are complicated, don't
131	ask). This type is called C<ev_tstamp>, which is what you should use	131	ask). This type is called C<ev_tstamp>, which is what you should use
132	too. It usually aliases to the C<double> type in C. When you need to do	132	too. It usually aliases to the C<double> type in C. When you need to do
133	any calculations on it, you should treat it as some floating point value.	133	any calculations on it, you should treat it as some floating point value.
134		134
…		…
292		292
293	=back	293	=back
294		294
295	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	295	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
296		296
297	An event loop is described by a C<struct ev_loop *> (the C<struct>	297	An event loop is described by a C<struct ev_loop *> (the C<struct> is
298	is I<not> optional in this case, as there is also an C<ev_loop>	298	I<not> optional in this case unless libev 3 compatibility is disabled, as
299	I<function>).	299	libev 3 had an C<ev_loop> function colliding with the struct name).
300		300
301	The library knows two types of such loops, the I<default> loop, which	301	The library knows two types of such loops, the I<default> loop, which
302	supports signals and child events, and dynamically created loops which do	302	supports signals and child events, and dynamically created event loops
303	not.	303	which do not.
304		304
305	=over 4	305	=over 4
306		306
307	=item struct ev_loop *ev_default_loop (unsigned int flags)	307	=item struct ev_loop *ev_default_loop (unsigned int flags)
308		308
…		…
439	of course I<doesn't>, and epoll just loves to report events for totally	439	of course I<doesn't>, and epoll just loves to report events for totally
440	I<different> file descriptors (even already closed ones, so one cannot	440	I<different> file descriptors (even already closed ones, so one cannot
441	even remove them from the set) than registered in the set (especially	441	even remove them from the set) than registered in the set (especially
442	on SMP systems). Libev tries to counter these spurious notifications by	442	on SMP systems). Libev tries to counter these spurious notifications by
443	employing an additional generation counter and comparing that against the	443	employing an additional generation counter and comparing that against the
444	events to filter out spurious ones, recreating the set when required.	444	events to filter out spurious ones, recreating the set when required. Last
		445	not least, it also refuses to work with some file descriptors which work
		446	perfectly fine with C<select> (files, many character devices...).
445		447
446	While stopping, setting and starting an I/O watcher in the same iteration	448	While stopping, setting and starting an I/O watcher in the same iteration
447	will result in some caching, there is still a system call per such	449	will result in some caching, there is still a system call per such
448	incident (because the same I<file descriptor> could point to a different	450	incident (because the same I<file descriptor> could point to a different
449	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	451	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
604	Like C<ev_default_destroy>, but destroys an event loop created by an	606	Like C<ev_default_destroy>, but destroys an event loop created by an
605	earlier call to C<ev_loop_new>.	607	earlier call to C<ev_loop_new>.
606		608
607	=item ev_default_fork ()	609	=item ev_default_fork ()
608		610
609	This function sets a flag that causes subsequent C<ev_loop> iterations	611	This function sets a flag that causes subsequent C<ev_run> iterations
610	to reinitialise the kernel state for backends that have one. Despite the	612	to reinitialise the kernel state for backends that have one. Despite the
611	name, you can call it anytime, but it makes most sense after forking, in	613	name, you can call it anytime, but it makes most sense after forking, in
612	the child process (or both child and parent, but that again makes little	614	the child process (or both child and parent, but that again makes little
613	sense). You I<must> call it in the child before using any of the libev	615	sense). You I<must> call it in the child before using any of the libev
614	functions, and it will only take effect at the next C<ev_loop> iteration.	616	functions, and it will only take effect at the next C<ev_run> iteration.
615		617
616	Again, you I<have> to call it on I<any> loop that you want to re-use after	618	Again, you I<have> to call it on I<any> loop that you want to re-use after
617	a fork, I<even if you do not plan to use the loop in the parent>. This is	619	a fork, I<even if you do not plan to use the loop in the parent>. This is
618	because some kernel interfaces cough I<kqueue> cough do funny things	620	because some kernel interfaces cough I<kqueue> cough do funny things
619	during fork.	621	during fork.
620		622
621	On the other hand, you only need to call this function in the child	623	On the other hand, you only need to call this function in the child
622	process if and only if you want to use the event loop in the child. If you	624	process if and only if you want to use the event loop in the child. If
623	just fork+exec or create a new loop in the child, you don't have to call	625	you just fork+exec or create a new loop in the child, you don't have to
624	it at all.	626	call it at all (in fact, C<epoll> is so badly broken that it makes a
		627	difference, but libev will usually detect this case on its own and do a
		628	costly reset of the backend).
625		629
626	The function itself is quite fast and it's usually not a problem to call	630	The function itself is quite fast and it's usually not a problem to call
627	it just in case after a fork. To make this easy, the function will fit in	631	it just in case after a fork. To make this easy, the function will fit in
628	quite nicely into a call to C<pthread_atfork>:	632	quite nicely into a call to C<pthread_atfork>:
629		633
…		…
641	Returns true when the given loop is, in fact, the default loop, and false	645	Returns true when the given loop is, in fact, the default loop, and false
642	otherwise.	646	otherwise.
643		647
644	=item unsigned int ev_iteration (loop)	648	=item unsigned int ev_iteration (loop)
645		649
646	Returns the current iteration count for the loop, which is identical to	650	Returns the current iteration count for the event loop, which is identical
647	the number of times libev did poll for new events. It starts at C<0> and	651	to the number of times libev did poll for new events. It starts at C<0>
648	happily wraps around with enough iterations.	652	and happily wraps around with enough iterations.
649		653
650	This value can sometimes be useful as a generation counter of sorts (it	654	This value can sometimes be useful as a generation counter of sorts (it
651	"ticks" the number of loop iterations), as it roughly corresponds with	655	"ticks" the number of loop iterations), as it roughly corresponds with
652	C<ev_prepare> and C<ev_check> calls - and is incremented between the	656	C<ev_prepare> and C<ev_check> calls - and is incremented between the
653	prepare and check phases.	657	prepare and check phases.
654		658
655	=item unsigned int ev_depth (loop)	659	=item unsigned int ev_depth (loop)
656		660
657	Returns the number of times C<ev_loop> was entered minus the number of	661	Returns the number of times C<ev_run> was entered minus the number of
658	times C<ev_loop> was exited, in other words, the recursion depth.	662	times C<ev_run> was exited, in other words, the recursion depth.
659		663
660	Outside C<ev_loop>, this number is zero. In a callback, this number is	664	Outside C<ev_run>, this number is zero. In a callback, this number is
661	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	665	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
662	in which case it is higher.	666	in which case it is higher.
663		667
664	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	668	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
665	etc.), doesn't count as "exit" - consider this as a hint to avoid such	669	etc.), doesn't count as "exit" - consider this as a hint to avoid such
666	ungentleman behaviour unless it's really convenient.	670	ungentleman-like behaviour unless it's really convenient.
667		671
668	=item unsigned int ev_backend (loop)	672	=item unsigned int ev_backend (loop)
669		673
670	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	674	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
671	use.	675	use.
…		…
680		684
681	=item ev_now_update (loop)	685	=item ev_now_update (loop)
682		686
683	Establishes the current time by querying the kernel, updating the time	687	Establishes the current time by querying the kernel, updating the time
684	returned by C<ev_now ()> in the progress. This is a costly operation and	688	returned by C<ev_now ()> in the progress. This is a costly operation and
685	is usually done automatically within C<ev_loop ()>.	689	is usually done automatically within C<ev_run ()>.
686		690
687	This function is rarely useful, but when some event callback runs for a	691	This function is rarely useful, but when some event callback runs for a
688	very long time without entering the event loop, updating libev's idea of	692	very long time without entering the event loop, updating libev's idea of
689	the current time is a good idea.	693	the current time is a good idea.
690		694
…		…
692		696
693	=item ev_suspend (loop)	697	=item ev_suspend (loop)
694		698
695	=item ev_resume (loop)	699	=item ev_resume (loop)
696		700
697	These two functions suspend and resume a loop, for use when the loop is	701	These two functions suspend and resume an event loop, for use when the
698	not used for a while and timeouts should not be processed.	702	loop is not used for a while and timeouts should not be processed.
699		703
700	A typical use case would be an interactive program such as a game: When	704	A typical use case would be an interactive program such as a game: When
701	the user presses C<^Z> to suspend the game and resumes it an hour later it	705	the user presses C<^Z> to suspend the game and resumes it an hour later it
702	would be best to handle timeouts as if no time had actually passed while	706	would be best to handle timeouts as if no time had actually passed while
703	the program was suspended. This can be achieved by calling C<ev_suspend>	707	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
714	without a previous call to C<ev_suspend>.	718	without a previous call to C<ev_suspend>.
715		719
716	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	720	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
717	event loop time (see C<ev_now_update>).	721	event loop time (see C<ev_now_update>).
718		722
719	=item ev_loop (loop, int flags)	723	=item ev_run (loop, int flags)
720		724
721	Finally, this is it, the event handler. This function usually is called	725	Finally, this is it, the event handler. This function usually is called
722	after you have initialised all your watchers and you want to start	726	after you have initialised all your watchers and you want to start
723	handling events.	727	handling events. It will ask the operating system for any new events, call
		728	the watcher callbacks, an then repeat the whole process indefinitely: This
		729	is why event loops are called I<loops>.
724		730
725	If the flags argument is specified as C<0>, it will not return until	731	If the flags argument is specified as C<0>, it will keep handling events
726	either no event watchers are active anymore or C<ev_unloop> was called.	732	until either no event watchers are active anymore or C<ev_break> was
		733	called.
727		734
728	Please note that an explicit C<ev_unloop> is usually better than	735	Please note that an explicit C<ev_break> is usually better than
729	relying on all watchers to be stopped when deciding when a program has	736	relying on all watchers to be stopped when deciding when a program has
730	finished (especially in interactive programs), but having a program	737	finished (especially in interactive programs), but having a program
731	that automatically loops as long as it has to and no longer by virtue	738	that automatically loops as long as it has to and no longer by virtue
732	of relying on its watchers stopping correctly, that is truly a thing of	739	of relying on its watchers stopping correctly, that is truly a thing of
733	beauty.	740	beauty.
734		741
735	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	742	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
736	those events and any already outstanding ones, but will not block your	743	those events and any already outstanding ones, but will not wait and
737	process in case there are no events and will return after one iteration of	744	block your process in case there are no events and will return after one
738	the loop.	745	iteration of the loop. This is sometimes useful to poll and handle new
		746	events while doing lengthy calculations, to keep the program responsive.
739		747
740	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	748	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
741	necessary) and will handle those and any already outstanding ones. It	749	necessary) and will handle those and any already outstanding ones. It
742	will block your process until at least one new event arrives (which could	750	will block your process until at least one new event arrives (which could
743	be an event internal to libev itself, so there is no guarantee that a	751	be an event internal to libev itself, so there is no guarantee that a
744	user-registered callback will be called), and will return after one	752	user-registered callback will be called), and will return after one
745	iteration of the loop.	753	iteration of the loop.
746		754
747	This is useful if you are waiting for some external event in conjunction	755	This is useful if you are waiting for some external event in conjunction
748	with something not expressible using other libev watchers (i.e. "roll your	756	with something not expressible using other libev watchers (i.e. "roll your
749	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	757	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
750	usually a better approach for this kind of thing.	758	usually a better approach for this kind of thing.
751		759
752	Here are the gory details of what C<ev_loop> does:	760	Here are the gory details of what C<ev_run> does:
753		761
		762	- Increment loop depth.
		763	- Reset the ev_break status.
754	- Before the first iteration, call any pending watchers.	764	- Before the first iteration, call any pending watchers.
		765	LOOP:
755	* If EVFLAG_FORKCHECK was used, check for a fork.	766	- If EVFLAG_FORKCHECK was used, check for a fork.
756	- If a fork was detected (by any means), queue and call all fork watchers.	767	- If a fork was detected (by any means), queue and call all fork watchers.
757	- Queue and call all prepare watchers.	768	- Queue and call all prepare watchers.
		769	- If ev_break was called, goto FINISH.
758	- If we have been forked, detach and recreate the kernel state	770	- If we have been forked, detach and recreate the kernel state
759	as to not disturb the other process.	771	as to not disturb the other process.
760	- Update the kernel state with all outstanding changes.	772	- Update the kernel state with all outstanding changes.
761	- Update the "event loop time" (ev_now ()).	773	- Update the "event loop time" (ev_now ()).
762	- Calculate for how long to sleep or block, if at all	774	- Calculate for how long to sleep or block, if at all
763	(active idle watchers, EVLOOP_NONBLOCK or not having	775	(active idle watchers, EVRUN_NOWAIT or not having
764	any active watchers at all will result in not sleeping).	776	any active watchers at all will result in not sleeping).
765	- Sleep if the I/O and timer collect interval say so.	777	- Sleep if the I/O and timer collect interval say so.
		778	- Increment loop iteration counter.
766	- Block the process, waiting for any events.	779	- Block the process, waiting for any events.
767	- Queue all outstanding I/O (fd) events.	780	- Queue all outstanding I/O (fd) events.
768	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	781	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
769	- Queue all expired timers.	782	- Queue all expired timers.
770	- Queue all expired periodics.	783	- Queue all expired periodics.
771	- Unless any events are pending now, queue all idle watchers.	784	- Queue all idle watchers with priority higher than that of pending events.
772	- Queue all check watchers.	785	- Queue all check watchers.
773	- Call all queued watchers in reverse order (i.e. check watchers first).	786	- Call all queued watchers in reverse order (i.e. check watchers first).
774	Signals and child watchers are implemented as I/O watchers, and will	787	Signals and child watchers are implemented as I/O watchers, and will
775	be handled here by queueing them when their watcher gets executed.	788	be handled here by queueing them when their watcher gets executed.
776	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	789	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
777	were used, or there are no active watchers, return, otherwise	790	were used, or there are no active watchers, goto FINISH, otherwise
778	continue with step *.	791	continue with step LOOP.
		792	FINISH:
		793	- Reset the ev_break status iff it was EVBREAK_ONE.
		794	- Decrement the loop depth.
		795	- Return.
779		796
780	Example: Queue some jobs and then loop until no events are outstanding	797	Example: Queue some jobs and then loop until no events are outstanding
781	anymore.	798	anymore.
782		799
783	... queue jobs here, make sure they register event watchers as long	800	... queue jobs here, make sure they register event watchers as long
784	... as they still have work to do (even an idle watcher will do..)	801	... as they still have work to do (even an idle watcher will do..)
785	ev_loop (my_loop, 0);	802	ev_run (my_loop, 0);
786	... jobs done or somebody called unloop. yeah!	803	... jobs done or somebody called unloop. yeah!
787		804
788	=item ev_unloop (loop, how)	805	=item ev_break (loop, how)
789		806
790	Can be used to make a call to C<ev_loop> return early (but only after it	807	Can be used to make a call to C<ev_run> return early (but only after it
791	has processed all outstanding events). The C<how> argument must be either	808	has processed all outstanding events). The C<how> argument must be either
792	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	809	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
793	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	810	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
794		811
795	This "unloop state" will be cleared when entering C<ev_loop> again.	812	This "unloop state" will be cleared when entering C<ev_run> again.
796		813
797	It is safe to call C<ev_unloop> from outside any C<ev_loop> calls.	814	It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO##
798		815
799	=item ev_ref (loop)	816	=item ev_ref (loop)
800		817
801	=item ev_unref (loop)	818	=item ev_unref (loop)
802		819
803	Ref/unref can be used to add or remove a reference count on the event	820	Ref/unref can be used to add or remove a reference count on the event
804	loop: Every watcher keeps one reference, and as long as the reference	821	loop: Every watcher keeps one reference, and as long as the reference
805	count is nonzero, C<ev_loop> will not return on its own.	822	count is nonzero, C<ev_run> will not return on its own.
806		823
807	This is useful when you have a watcher that you never intend to	824	This is useful when you have a watcher that you never intend to
808	unregister, but that nevertheless should not keep C<ev_loop> from	825	unregister, but that nevertheless should not keep C<ev_run> from
809	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	826	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
810	before stopping it.	827	before stopping it.
811		828
812	As an example, libev itself uses this for its internal signal pipe: It	829	As an example, libev itself uses this for its internal signal pipe: It
813	is not visible to the libev user and should not keep C<ev_loop> from	830	is not visible to the libev user and should not keep C<ev_run> from
814	exiting if no event watchers registered by it are active. It is also an	831	exiting if no event watchers registered by it are active. It is also an
815	excellent way to do this for generic recurring timers or from within	832	excellent way to do this for generic recurring timers or from within
816	third-party libraries. Just remember to I<unref after start> and I<ref	833	third-party libraries. Just remember to I<unref after start> and I<ref
817	before stop> (but only if the watcher wasn't active before, or was active	834	before stop> (but only if the watcher wasn't active before, or was active
818	before, respectively. Note also that libev might stop watchers itself	835	before, respectively. Note also that libev might stop watchers itself
819	(e.g. non-repeating timers) in which case you have to C<ev_ref>	836	(e.g. non-repeating timers) in which case you have to C<ev_ref>
820	in the callback).	837	in the callback).
821		838
822	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	839	Example: Create a signal watcher, but keep it from keeping C<ev_run>
823	running when nothing else is active.	840	running when nothing else is active.
824		841
825	ev_signal exitsig;	842	ev_signal exitsig;
826	ev_signal_init (&exitsig, sig_cb, SIGINT);	843	ev_signal_init (&exitsig, sig_cb, SIGINT);
827	ev_signal_start (loop, &exitsig);	844	ev_signal_start (loop, &exitsig);
…		…
890	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	907	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
891		908
892	=item ev_invoke_pending (loop)	909	=item ev_invoke_pending (loop)
893		910
894	This call will simply invoke all pending watchers while resetting their	911	This call will simply invoke all pending watchers while resetting their
895	pending state. Normally, C<ev_loop> does this automatically when required,	912	pending state. Normally, C<ev_run> does this automatically when required,
896	but when overriding the invoke callback this call comes handy.	913	but when overriding the invoke callback this call comes handy. This
		914	function can be invoked from a watcher - this can be useful for example
		915	when you want to do some lengthy calculation and want to pass further
		916	event handling to another thread (you still have to make sure only one
		917	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
897		918
898	=item int ev_pending_count (loop)	919	=item int ev_pending_count (loop)
899		920
900	Returns the number of pending watchers - zero indicates that no watchers	921	Returns the number of pending watchers - zero indicates that no watchers
901	are pending.	922	are pending.
902		923
903	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	924	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
904		925
905	This overrides the invoke pending functionality of the loop: Instead of	926	This overrides the invoke pending functionality of the loop: Instead of
906	invoking all pending watchers when there are any, C<ev_loop> will call	927	invoking all pending watchers when there are any, C<ev_run> will call
907	this callback instead. This is useful, for example, when you want to	928	this callback instead. This is useful, for example, when you want to
908	invoke the actual watchers inside another context (another thread etc.).	929	invoke the actual watchers inside another context (another thread etc.).
909		930
910	If you want to reset the callback, use C<ev_invoke_pending> as new	931	If you want to reset the callback, use C<ev_invoke_pending> as new
911	callback.	932	callback.
…		…
914		935
915	Sometimes you want to share the same loop between multiple threads. This	936	Sometimes you want to share the same loop between multiple threads. This
916	can be done relatively simply by putting mutex_lock/unlock calls around	937	can be done relatively simply by putting mutex_lock/unlock calls around
917	each call to a libev function.	938	each call to a libev function.
918		939
919	However, C<ev_loop> can run an indefinite time, so it is not feasible to	940	However, C<ev_run> can run an indefinite time, so it is not feasible
920	wait for it to return. One way around this is to wake up the loop via	941	to wait for it to return. One way around this is to wake up the event
921	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	942	loop via C<ev_break> and C<av_async_send>, another way is to set these
922	and I<acquire> callbacks on the loop.	943	I<release> and I<acquire> callbacks on the loop.
923		944
924	When set, then C<release> will be called just before the thread is	945	When set, then C<release> will be called just before the thread is
925	suspended waiting for new events, and C<acquire> is called just	946	suspended waiting for new events, and C<acquire> is called just
926	afterwards.	947	afterwards.
927		948
…		…
930		951
931	While event loop modifications are allowed between invocations of	952	While event loop modifications are allowed between invocations of
932	C<release> and C<acquire> (that's their only purpose after all), no	953	C<release> and C<acquire> (that's their only purpose after all), no
933	modifications done will affect the event loop, i.e. adding watchers will	954	modifications done will affect the event loop, i.e. adding watchers will
934	have no effect on the set of file descriptors being watched, or the time	955	have no effect on the set of file descriptors being watched, or the time
935	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	956	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
936	to take note of any changes you made.	957	to take note of any changes you made.
937		958
938	In theory, threads executing C<ev_loop> will be async-cancel safe between	959	In theory, threads executing C<ev_run> will be async-cancel safe between
939	invocations of C<release> and C<acquire>.	960	invocations of C<release> and C<acquire>.
940		961
941	See also the locking example in the C<THREADS> section later in this	962	See also the locking example in the C<THREADS> section later in this
942	document.	963	document.
943		964
…		…
952	These two functions can be used to associate arbitrary data with a loop,	973	These two functions can be used to associate arbitrary data with a loop,
953	and are intended solely for the C<invoke_pending_cb>, C<release> and	974	and are intended solely for the C<invoke_pending_cb>, C<release> and
954	C<acquire> callbacks described above, but of course can be (ab-)used for	975	C<acquire> callbacks described above, but of course can be (ab-)used for
955	any other purpose as well.	976	any other purpose as well.
956		977
957	=item ev_loop_verify (loop)	978	=item ev_verify (loop)
958		979
959	This function only does something when C<EV_VERIFY> support has been	980	This function only does something when C<EV_VERIFY> support has been
960	compiled in, which is the default for non-minimal builds. It tries to go	981	compiled in, which is the default for non-minimal builds. It tries to go
961	through all internal structures and checks them for validity. If anything	982	through all internal structures and checks them for validity. If anything
962	is found to be inconsistent, it will print an error message to standard	983	is found to be inconsistent, it will print an error message to standard
…		…
973		994
974	In the following description, uppercase C<TYPE> in names stands for the	995	In the following description, uppercase C<TYPE> in names stands for the
975	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	996	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
976	watchers and C<ev_io_start> for I/O watchers.	997	watchers and C<ev_io_start> for I/O watchers.
977		998
978	A watcher is a structure that you create and register to record your	999	A watcher is an opaque structure that you allocate and register to record
979	interest in some event. For instance, if you want to wait for STDIN to	1000	your interest in some event. To make a concrete example, imagine you want
980	become readable, you would create an C<ev_io> watcher for that:	1001	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1002	for that:
981		1003
982	static void my_cb (struct ev_loop loop, ev_io w, int revents)	1004	static void my_cb (struct ev_loop loop, ev_io w, int revents)
983	{	1005	{
984	ev_io_stop (w);	1006	ev_io_stop (w);
985	ev_unloop (loop, EVUNLOOP_ALL);	1007	ev_break (loop, EVBREAK_ALL);
986	}	1008	}
987		1009
988	struct ev_loop *loop = ev_default_loop (0);	1010	struct ev_loop *loop = ev_default_loop (0);
989		1011
990	ev_io stdin_watcher;	1012	ev_io stdin_watcher;
991		1013
992	ev_init (&stdin_watcher, my_cb);	1014	ev_init (&stdin_watcher, my_cb);
993	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1015	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
994	ev_io_start (loop, &stdin_watcher);	1016	ev_io_start (loop, &stdin_watcher);
995		1017
996	ev_loop (loop, 0);	1018	ev_run (loop, 0);
997		1019
998	As you can see, you are responsible for allocating the memory for your	1020	As you can see, you are responsible for allocating the memory for your
999	watcher structures (and it is I<usually> a bad idea to do this on the	1021	watcher structures (and it is I<usually> a bad idea to do this on the
1000	stack).	1022	stack).
1001		1023
1002	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1024	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
1003	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1025	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
1004		1026
1005	Each watcher structure must be initialised by a call to C<ev_init	1027	Each watcher structure must be initialised by a call to C<ev_init (watcher
1006	(watcher *, callback)>, which expects a callback to be provided. This	1028	*, callback)>, which expects a callback to be provided. This callback is
1007	callback gets invoked each time the event occurs (or, in the case of I/O	1029	invoked each time the event occurs (or, in the case of I/O watchers, each
1008	watchers, each time the event loop detects that the file descriptor given	1030	time the event loop detects that the file descriptor given is readable
1009	is readable and/or writable).	1031	and/or writable).
1010		1032
1011	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1033	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1012	macro to configure it, with arguments specific to the watcher type. There	1034	macro to configure it, with arguments specific to the watcher type. There
1013	is also a macro to combine initialisation and setting in one call: C<<	1035	is also a macro to combine initialisation and setting in one call: C<<
1014	ev_TYPE_init (watcher *, callback, ...) >>.	1036	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1065		1087
1066	=item C<EV_PREPARE>	1088	=item C<EV_PREPARE>
1067		1089
1068	=item C<EV_CHECK>	1090	=item C<EV_CHECK>
1069		1091
1070	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1092	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1071	to gather new events, and all C<ev_check> watchers are invoked just after	1093	to gather new events, and all C<ev_check> watchers are invoked just after
1072	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1094	C<ev_run> has gathered them, but before it invokes any callbacks for any
1073	received events. Callbacks of both watcher types can start and stop as	1095	received events. Callbacks of both watcher types can start and stop as
1074	many watchers as they want, and all of them will be taken into account	1096	many watchers as they want, and all of them will be taken into account
1075	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1097	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1076	C<ev_loop> from blocking).	1098	C<ev_run> from blocking).
1077		1099
1078	=item C<EV_EMBED>	1100	=item C<EV_EMBED>
1079		1101
1080	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1102	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1081		1103
…		…
1109	example it might indicate that a fd is readable or writable, and if your	1131	example it might indicate that a fd is readable or writable, and if your
1110	callbacks is well-written it can just attempt the operation and cope with	1132	callbacks is well-written it can just attempt the operation and cope with
1111	the error from read() or write(). This will not work in multi-threaded	1133	the error from read() or write(). This will not work in multi-threaded
1112	programs, though, as the fd could already be closed and reused for another	1134	programs, though, as the fd could already be closed and reused for another
1113	thing, so beware.	1135	thing, so beware.
		1136
		1137	=back
		1138
		1139	=head2 WATCHER STATES
		1140
		1141	There are various watcher states mentioned throughout this manual -
		1142	active, pending and so on. In this section these states and the rules to
		1143	transition between them will be described in more detail - and while these
		1144	rules might look complicated, they usually do "the right thing".
		1145
		1146	=over 4
		1147
		1148	=item initialiased
		1149
		1150	Before a watcher can be registered with the event looop it has to be
		1151	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1152	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1153
		1154	In this state it is simply some block of memory that is suitable for use
		1155	in an event loop. It can be moved around, freed, reused etc. at will.
		1156
		1157	=item started/running/active
		1158
		1159	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1160	property of the event loop, and is actively waiting for events. While in
		1161	this state it cannot be accessed (except in a few documented ways), moved,
		1162	freed or anything else - the only legal thing is to keep a pointer to it,
		1163	and call libev functions on it that are documented to work on active watchers.
		1164
		1165	=item pending
		1166
		1167	If a watcher is active and libev determines that an event it is interested
		1168	in has occurred (such as a timer expiring), it will become pending. It will
		1169	stay in this pending state until either it is stopped or its callback is
		1170	about to be invoked, so it is not normally pending inside the watcher
		1171	callback.
		1172
		1173	The watcher might or might not be active while it is pending (for example,
		1174	an expired non-repeating timer can be pending but no longer active). If it
		1175	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1176	but it is still property of the event loop at this time, so cannot be
		1177	moved, freed or reused. And if it is active the rules described in the
		1178	previous item still apply.
		1179
		1180	It is also possible to feed an event on a watcher that is not active (e.g.
		1181	via C<ev_feed_event>), in which case it becomes pending without being
		1182	active.
		1183
		1184	=item stopped
		1185
		1186	A watcher can be stopped implicitly by libev (in which case it might still
		1187	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1188	latter will clear any pending state the watcher might be in, regardless
		1189	of whether it was active or not, so stopping a watcher explicitly before
		1190	freeing it is often a good idea.
		1191
		1192	While stopped (and not pending) the watcher is essentially in the
		1193	initialised state, that is it can be reused, moved, modified in any way
		1194	you wish.
1114		1195
1115	=back	1196	=back
1116		1197
1117	=head2 GENERIC WATCHER FUNCTIONS	1198	=head2 GENERIC WATCHER FUNCTIONS
1118		1199
…		…
1622	...	1703	...
1623	struct ev_loop *loop = ev_default_init (0);	1704	struct ev_loop *loop = ev_default_init (0);
1624	ev_io stdin_readable;	1705	ev_io stdin_readable;
1625	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1706	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1626	ev_io_start (loop, &stdin_readable);	1707	ev_io_start (loop, &stdin_readable);
1627	ev_loop (loop, 0);	1708	ev_run (loop, 0);
1628		1709
1629		1710
1630	=head2 C<ev_timer> - relative and optionally repeating timeouts	1711	=head2 C<ev_timer> - relative and optionally repeating timeouts
1631		1712
1632	Timer watchers are simple relative timers that generate an event after a	1713	Timer watchers are simple relative timers that generate an event after a
…		…
1641	The callback is guaranteed to be invoked only I<after> its timeout has	1722	The callback is guaranteed to be invoked only I<after> its timeout has
1642	passed (not I<at>, so on systems with very low-resolution clocks this	1723	passed (not I<at>, so on systems with very low-resolution clocks this
1643	might introduce a small delay). If multiple timers become ready during the	1724	might introduce a small delay). If multiple timers become ready during the
1644	same loop iteration then the ones with earlier time-out values are invoked	1725	same loop iteration then the ones with earlier time-out values are invoked
1645	before ones of the same priority with later time-out values (but this is	1726	before ones of the same priority with later time-out values (but this is
1646	no longer true when a callback calls C<ev_loop> recursively).	1727	no longer true when a callback calls C<ev_run> recursively).
1647		1728
1648	=head3 Be smart about timeouts	1729	=head3 Be smart about timeouts
1649		1730
1650	Many real-world problems involve some kind of timeout, usually for error	1731	Many real-world problems involve some kind of timeout, usually for error
1651	recovery. A typical example is an HTTP request - if the other side hangs,	1732	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1822		1903
1823	=head3 The special problem of time updates	1904	=head3 The special problem of time updates
1824		1905
1825	Establishing the current time is a costly operation (it usually takes at	1906	Establishing the current time is a costly operation (it usually takes at
1826	least two system calls): EV therefore updates its idea of the current	1907	least two system calls): EV therefore updates its idea of the current
1827	time only before and after C<ev_loop> collects new events, which causes a	1908	time only before and after C<ev_run> collects new events, which causes a
1828	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1909	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1829	lots of events in one iteration.	1910	lots of events in one iteration.
1830		1911
1831	The relative timeouts are calculated relative to the C<ev_now ()>	1912	The relative timeouts are calculated relative to the C<ev_now ()>
1832	time. This is usually the right thing as this timestamp refers to the time	1913	time. This is usually the right thing as this timestamp refers to the time
…		…
1949	}	2030	}
1950		2031
1951	ev_timer mytimer;	2032	ev_timer mytimer;
1952	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2033	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1953	ev_timer_again (&mytimer); /* start timer */	2034	ev_timer_again (&mytimer); /* start timer */
1954	ev_loop (loop, 0);	2035	ev_run (loop, 0);
1955		2036
1956	// and in some piece of code that gets executed on any "activity":	2037	// and in some piece of code that gets executed on any "activity":
1957	// reset the timeout to start ticking again at 10 seconds	2038	// reset the timeout to start ticking again at 10 seconds
1958	ev_timer_again (&mytimer);	2039	ev_timer_again (&mytimer);
1959		2040
…		…
1985		2066
1986	As with timers, the callback is guaranteed to be invoked only when the	2067	As with timers, the callback is guaranteed to be invoked only when the
1987	point in time where it is supposed to trigger has passed. If multiple	2068	point in time where it is supposed to trigger has passed. If multiple
1988	timers become ready during the same loop iteration then the ones with	2069	timers become ready during the same loop iteration then the ones with
1989	earlier time-out values are invoked before ones with later time-out values	2070	earlier time-out values are invoked before ones with later time-out values
1990	(but this is no longer true when a callback calls C<ev_loop> recursively).	2071	(but this is no longer true when a callback calls C<ev_run> recursively).
1991		2072
1992	=head3 Watcher-Specific Functions and Data Members	2073	=head3 Watcher-Specific Functions and Data Members
1993		2074
1994	=over 4	2075	=over 4
1995		2076
…		…
2233	Example: Try to exit cleanly on SIGINT.	2314	Example: Try to exit cleanly on SIGINT.
2234		2315
2235	static void	2316	static void
2236	sigint_cb (struct ev_loop loop, ev_signal w, int revents)	2317	sigint_cb (struct ev_loop loop, ev_signal w, int revents)
2237	{	2318	{
2238	ev_unloop (loop, EVUNLOOP_ALL);	2319	ev_break (loop, EVBREAK_ALL);
2239	}	2320	}
2240		2321
2241	ev_signal signal_watcher;	2322	ev_signal signal_watcher;
2242	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2323	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2243	ev_signal_start (loop, &signal_watcher);	2324	ev_signal_start (loop, &signal_watcher);
…		…
2629		2710
2630	Prepare and check watchers are usually (but not always) used in pairs:	2711	Prepare and check watchers are usually (but not always) used in pairs:
2631	prepare watchers get invoked before the process blocks and check watchers	2712	prepare watchers get invoked before the process blocks and check watchers
2632	afterwards.	2713	afterwards.
2633		2714
2634	You I<must not> call C<ev_loop> or similar functions that enter	2715	You I<must not> call C<ev_run> or similar functions that enter
2635	the current event loop from either C<ev_prepare> or C<ev_check>	2716	the current event loop from either C<ev_prepare> or C<ev_check>
2636	watchers. Other loops than the current one are fine, however. The	2717	watchers. Other loops than the current one are fine, however. The
2637	rationale behind this is that you do not need to check for recursion in	2718	rationale behind this is that you do not need to check for recursion in
2638	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2719	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2639	C<ev_check> so if you have one watcher of each kind they will always be	2720	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2807		2888
2808	if (timeout >= 0)	2889	if (timeout >= 0)
2809	// create/start timer	2890	// create/start timer
2810		2891
2811	// poll	2892	// poll
2812	ev_loop (EV_A_ 0);	2893	ev_run (EV_A_ 0);
2813		2894
2814	// stop timer again	2895	// stop timer again
2815	if (timeout >= 0)	2896	if (timeout >= 0)
2816	ev_timer_stop (EV_A_ &to);	2897	ev_timer_stop (EV_A_ &to);
2817		2898
…		…
2895	if you do not want that, you need to temporarily stop the embed watcher).	2976	if you do not want that, you need to temporarily stop the embed watcher).
2896		2977
2897	=item ev_embed_sweep (loop, ev_embed *)	2978	=item ev_embed_sweep (loop, ev_embed *)
2898		2979
2899	Make a single, non-blocking sweep over the embedded loop. This works	2980	Make a single, non-blocking sweep over the embedded loop. This works
2900	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2981	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2901	appropriate way for embedded loops.	2982	appropriate way for embedded loops.
2902		2983
2903	=item struct ev_loop *other [read-only]	2984	=item struct ev_loop *other [read-only]
2904		2985
2905	The embedded event loop.	2986	The embedded event loop.
…		…
3011	=back	3092	=back
3012		3093
3013		3094
3014	=head2 C<ev_async> - how to wake up an event loop	3095	=head2 C<ev_async> - how to wake up an event loop
3015		3096
3016	In general, you cannot use an C<ev_loop> from multiple threads or other	3097	In general, you cannot use an C<ev_run> from multiple threads or other
3017	asynchronous sources such as signal handlers (as opposed to multiple event	3098	asynchronous sources such as signal handlers (as opposed to multiple event
3018	loops - those are of course safe to use in different threads).	3099	loops - those are of course safe to use in different threads).
3019		3100
3020	Sometimes, however, you need to wake up an event loop you do not control,	3101	Sometimes, however, you need to wake up an event loop you do not control,
3021	for example because it belongs to another thread. This is what C<ev_async>	3102	for example because it belongs to another thread. This is what C<ev_async>
…		…
3389	Associates a different C<struct ev_loop> with this watcher. You can only	3470	Associates a different C<struct ev_loop> with this watcher. You can only
3390	do this when the watcher is inactive (and not pending either).	3471	do this when the watcher is inactive (and not pending either).
3391		3472
3392	=item w->set ([arguments])	3473	=item w->set ([arguments])
3393		3474
3394	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3475	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3395	called at least once. Unlike the C counterpart, an active watcher gets	3476	method or a suitable start method must be called at least once. Unlike the
3396	automatically stopped and restarted when reconfiguring it with this	3477	C counterpart, an active watcher gets automatically stopped and restarted
3397	method.	3478	when reconfiguring it with this method.
3398		3479
3399	=item w->start ()	3480	=item w->start ()
3400		3481
3401	Starts the watcher. Note that there is no C<loop> argument, as the	3482	Starts the watcher. Note that there is no C<loop> argument, as the
3402	constructor already stores the event loop.	3483	constructor already stores the event loop.
3403		3484
		3485	=item w->start ([arguments])
		3486
		3487	Instead of calling C<set> and C<start> methods separately, it is often
		3488	convenient to wrap them in one call. Uses the same type of arguments as
		3489	the configure C<set> method of the watcher.
		3490
3404	=item w->stop ()	3491	=item w->stop ()
3405		3492
3406	Stops the watcher if it is active. Again, no C<loop> argument.	3493	Stops the watcher if it is active. Again, no C<loop> argument.
3407		3494
3408	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3495	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3420		3507
3421	=back	3508	=back
3422		3509
3423	=back	3510	=back
3424		3511
3425	Example: Define a class with an IO and idle watcher, start one of them in	3512	Example: Define a class with two I/O and idle watchers, start the I/O
3426	the constructor.	3513	watchers in the constructor.
3427		3514
3428	class myclass	3515	class myclass
3429	{	3516	{
3430	ev::io io ; void io_cb (ev::io &w, int revents);	3517	ev::io io ; void io_cb (ev::io &w, int revents);
		3518	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3431	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3519	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3432		3520
3433	myclass (int fd)	3521	myclass (int fd)
3434	{	3522	{
3435	io .set <myclass, &myclass::io_cb > (this);	3523	io .set <myclass, &myclass::io_cb > (this);
		3524	io2 .set <myclass, &myclass::io2_cb > (this);
3436	idle.set <myclass, &myclass::idle_cb> (this);	3525	idle.set <myclass, &myclass::idle_cb> (this);
3437		3526
3438	io.start (fd, ev::READ);	3527	io.set (fd, ev::WRITE); // configure the watcher
		3528	io.start (); // start it whenever convenient
		3529
		3530	io2.start (fd, ev::READ); // set + start in one call
3439	}	3531	}
3440	};	3532	};
3441		3533
3442		3534
3443	=head1 OTHER LANGUAGE BINDINGS	3535	=head1 OTHER LANGUAGE BINDINGS
…		…
3517	loop argument"). The C<EV_A> form is used when this is the sole argument,	3609	loop argument"). The C<EV_A> form is used when this is the sole argument,
3518	C<EV_A_> is used when other arguments are following. Example:	3610	C<EV_A_> is used when other arguments are following. Example:
3519		3611
3520	ev_unref (EV_A);	3612	ev_unref (EV_A);
3521	ev_timer_add (EV_A_ watcher);	3613	ev_timer_add (EV_A_ watcher);
3522	ev_loop (EV_A_ 0);	3614	ev_run (EV_A_ 0);
3523		3615
3524	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3616	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3525	which is often provided by the following macro.	3617	which is often provided by the following macro.
3526		3618
3527	=item C<EV_P>, C<EV_P_>	3619	=item C<EV_P>, C<EV_P_>
…		…
3567	}	3659	}
3568		3660
3569	ev_check check;	3661	ev_check check;
3570	ev_check_init (&check, check_cb);	3662	ev_check_init (&check, check_cb);
3571	ev_check_start (EV_DEFAULT_ &check);	3663	ev_check_start (EV_DEFAULT_ &check);
3572	ev_loop (EV_DEFAULT_ 0);	3664	ev_run (EV_DEFAULT_ 0);
3573		3665
3574	=head1 EMBEDDING	3666	=head1 EMBEDDING
3575		3667
3576	Libev can (and often is) directly embedded into host	3668	Libev can (and often is) directly embedded into host
3577	applications. Examples of applications that embed it include the Deliantra	3669	applications. Examples of applications that embed it include the Deliantra
…		…
3668	to a compiled library. All other symbols change the ABI, which means all	3760	to a compiled library. All other symbols change the ABI, which means all
3669	users of libev and the libev code itself must be compiled with compatible	3761	users of libev and the libev code itself must be compiled with compatible
3670	settings.	3762	settings.
3671		3763
3672	=over 4	3764	=over 4
		3765
		3766	=item EV_COMPAT3 (h)
		3767
		3768	Backwards compatibility is a major concern for libev. This is why this
		3769	release of libev comes with wrappers for the functions and symbols that
		3770	have been renamed between libev version 3 and 4.
		3771
		3772	You can disable these wrappers (to test compatibility with future
		3773	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3774	sources. This has the additional advantage that you can drop the C<struct>
		3775	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3776	typedef in that case.
		3777
		3778	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3779	and in some even more future version the compatibility code will be
		3780	removed completely.
3673		3781
3674	=item EV_STANDALONE (h)	3782	=item EV_STANDALONE (h)
3675		3783
3676	Must always be C<1> if you do not use autoconf configuration, which	3784	Must always be C<1> if you do not use autoconf configuration, which
3677	keeps libev from including F<config.h>, and it also defines dummy	3785	keeps libev from including F<config.h>, and it also defines dummy
…		…
4027	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it	4135	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4028	will be C<0>.	4136	will be C<0>.
4029		4137
4030	=item EV_VERIFY	4138	=item EV_VERIFY
4031		4139
4032	Controls how much internal verification (see C<ev_loop_verify ()>) will	4140	Controls how much internal verification (see C<ev_verify ()>) will
4033	be done: If set to C<0>, no internal verification code will be compiled	4141	be done: If set to C<0>, no internal verification code will be compiled
4034	in. If set to C<1>, then verification code will be compiled in, but not	4142	in. If set to C<1>, then verification code will be compiled in, but not
4035	called. If set to C<2>, then the internal verification code will be	4143	called. If set to C<2>, then the internal verification code will be
4036	called once per loop, which can slow down libev. If set to C<3>, then the	4144	called once per loop, which can slow down libev. If set to C<3>, then the
4037	verification code will be called very frequently, which will slow down	4145	verification code will be called very frequently, which will slow down
…		…
4252	userdata *u = ev_userdata (EV_A);	4360	userdata *u = ev_userdata (EV_A);
4253	pthread_mutex_lock (&u->lock);	4361	pthread_mutex_lock (&u->lock);
4254	}	4362	}
4255		4363
4256	The event loop thread first acquires the mutex, and then jumps straight	4364	The event loop thread first acquires the mutex, and then jumps straight
4257	into C<ev_loop>:	4365	into C<ev_run>:
4258		4366
4259	void *	4367	void *
4260	l_run (void *thr_arg)	4368	l_run (void *thr_arg)
4261	{	4369	{
4262	struct ev_loop loop = (struct ev_loop )thr_arg;	4370	struct ev_loop loop = (struct ev_loop )thr_arg;
4263		4371
4264	l_acquire (EV_A);	4372	l_acquire (EV_A);
4265	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4373	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4266	ev_loop (EV_A_ 0);	4374	ev_run (EV_A_ 0);
4267	l_release (EV_A);	4375	l_release (EV_A);
4268		4376
4269	return 0;	4377	return 0;
4270	}	4378	}
4271		4379
…		…
4323		4431
4324	=head3 COROUTINES	4432	=head3 COROUTINES
4325		4433
4326	Libev is very accommodating to coroutines ("cooperative threads"):	4434	Libev is very accommodating to coroutines ("cooperative threads"):
4327	libev fully supports nesting calls to its functions from different	4435	libev fully supports nesting calls to its functions from different
4328	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4436	coroutines (e.g. you can call C<ev_run> on the same loop from two
4329	different coroutines, and switch freely between both coroutines running	4437	different coroutines, and switch freely between both coroutines running
4330	the loop, as long as you don't confuse yourself). The only exception is	4438	the loop, as long as you don't confuse yourself). The only exception is
4331	that you must not do this from C<ev_periodic> reschedule callbacks.	4439	that you must not do this from C<ev_periodic> reschedule callbacks.
4332		4440
4333	Care has been taken to ensure that libev does not keep local state inside	4441	Care has been taken to ensure that libev does not keep local state inside
4334	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4442	C<ev_run>, and other calls do not usually allow for coroutine switches as
4335	they do not call any callbacks.	4443	they do not call any callbacks.
4336		4444
4337	=head2 COMPILER WARNINGS	4445	=head2 COMPILER WARNINGS
4338		4446
4339	Depending on your compiler and compiler settings, you might get no or a	4447	Depending on your compiler and compiler settings, you might get no or a
…		…
4423	=head3 C<kqueue> is buggy	4531	=head3 C<kqueue> is buggy
4424		4532
4425	The kqueue syscall is broken in all known versions - most versions support	4533	The kqueue syscall is broken in all known versions - most versions support
4426	only sockets, many support pipes.	4534	only sockets, many support pipes.
4427		4535
4428	Libev tries to work around this by not using C<kqueue> by default on	4536	Libev tries to work around this by not using C<kqueue> by default on this
4429	this rotten platform, but of course you can still ask for it when creating	4537	rotten platform, but of course you can still ask for it when creating a
4430	a loop.	4538	loop - embedding a socket-only kqueue loop into a select-based one is
		4539	probably going to work well.
4431		4540
4432	=head3 C<poll> is buggy	4541	=head3 C<poll> is buggy
4433		4542
4434	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>	4543	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
4435	implementation by something calling C<kqueue> internally around the 10.5.6	4544	implementation by something calling C<kqueue> internally around the 10.5.6
…		…
4454		4563
4455	=head3 C<errno> reentrancy	4564	=head3 C<errno> reentrancy
4456		4565
4457	The default compile environment on Solaris is unfortunately so	4566	The default compile environment on Solaris is unfortunately so
4458	thread-unsafe that you can't even use components/libraries compiled	4567	thread-unsafe that you can't even use components/libraries compiled
4459	without C<-D_REENTRANT> (as long as they use C<errno>), which, of course,	4568	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
4460	isn't defined by default.	4569	defined by default. A valid, if stupid, implementation choice.
4461		4570
4462	If you want to use libev in threaded environments you have to make sure	4571	If you want to use libev in threaded environments you have to make sure
4463	it's compiled with C<_REENTRANT> defined.	4572	it's compiled with C<_REENTRANT> defined.
4464		4573
4465	=head3 Event port backend	4574	=head3 Event port backend
4466		4575
4467	The scalable event interface for Solaris is called "event ports". Unfortunately,	4576	The scalable event interface for Solaris is called "event
4468	this mechanism is very buggy. If you run into high CPU usage, your program	4577	ports". Unfortunately, this mechanism is very buggy in all major
		4578	releases. If you run into high CPU usage, your program freezes or you get
4469	freezes or you get a large number of spurious wakeups, make sure you have	4579	a large number of spurious wakeups, make sure you have all the relevant
4470	all the relevant and latest kernel patches applied. No, I don't know which	4580	and latest kernel patches applied. No, I don't know which ones, but there
4471	ones, but there are multiple ones.	4581	are multiple ones to apply, and afterwards, event ports actually work
		4582	great.
4472		4583
4473	If you can't get it to work, you can try running the program by setting	4584	If you can't get it to work, you can try running the program by setting
4474	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and	4585	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
4475	C<select> backends.	4586	C<select> backends.
4476		4587
4477	=head2 AIX POLL BUG	4588	=head2 AIX POLL BUG
4478		4589
4479	AIX unfortunately has a broken C<poll.h> header. Libev works around	4590	AIX unfortunately has a broken C<poll.h> header. Libev works around
4480	this by trying to avoid the poll backend altogether (i.e. it's not even	4591	this by trying to avoid the poll backend altogether (i.e. it's not even
4481	compiled in), which normally isn't a big problem as C<select> works fine	4592	compiled in), which normally isn't a big problem as C<select> works fine
4482	with large bitsets, and AIX is dead anyway.	4593	with large bitsets on AIX, and AIX is dead anyway.
4483		4594
4484	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4595	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
4485		4596
4486	=head3 General issues	4597	=head3 General issues
4487		4598
…		…
4624	watchers.	4735	watchers.
4625		4736
4626	=item C<double> must hold a time value in seconds with enough accuracy	4737	=item C<double> must hold a time value in seconds with enough accuracy
4627		4738
4628	The type C<double> is used to represent timestamps. It is required to	4739	The type C<double> is used to represent timestamps. It is required to
4629	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4740	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4630	enough for at least into the year 4000. This requirement is fulfilled by	4741	good enough for at least into the year 4000 with millisecond accuracy
		4742	(the design goal for libev). This requirement is overfulfilled by
4631	implementations implementing IEEE 754, which is basically all existing	4743	implementations using IEEE 754, which is basically all existing ones. With
4632	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4744	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4633	2200.
4634		4745
4635	=back	4746	=back
4636		4747
4637	If you know of other additional requirements drop me a note.	4748	If you know of other additional requirements drop me a note.
4638		4749
…		…
4716	compatibility, so most programs should still compile. Those might be	4827	compatibility, so most programs should still compile. Those might be
4717	removed in later versions of libev, so better update early than late.	4828	removed in later versions of libev, so better update early than late.
4718		4829
4719	=over 4	4830	=over 4
4720		4831
4721	=item C<ev_loop_count> renamed to C<ev_iteration>	4832	=item function/symbol renames
4722		4833
4723	=item C<ev_loop_depth> renamed to C<ev_depth>	4834	A number of functions and symbols have been renamed:
4724		4835
4725	=item C<ev_loop_verify> renamed to C<ev_verify>	4836	ev_loop => ev_run
		4837	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4838	EVLOOP_ONESHOT => EVRUN_ONCE
		4839
		4840	ev_unloop => ev_break
		4841	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4842	EVUNLOOP_ONE => EVBREAK_ONE
		4843	EVUNLOOP_ALL => EVBREAK_ALL
		4844
		4845	EV_TIMEOUT => EV_TIMER
		4846
		4847	ev_loop_count => ev_iteration
		4848	ev_loop_depth => ev_depth
		4849	ev_loop_verify => ev_verify
4726		4850
4727	Most functions working on C<struct ev_loop> objects don't have an	4851	Most functions working on C<struct ev_loop> objects don't have an
4728	C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is	4852	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4853	associated constants have been renamed to not collide with the C<struct
		4854	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4855	as all other watcher types. Note that C<ev_loop_fork> is still called
4729	still called C<ev_loop_fork> because it would otherwise clash with the	4856	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4730	C<ev_fork> typedef.	4857	typedef.
4731		4858
4732	=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents>	4859	=item C<EV_COMPAT3> backwards compatibility mechanism
4733		4860
4734	This is a simple rename - all other watcher types use their name	4861	The backward compatibility mechanism can be controlled by
4735	as revents flag, and now C<ev_timer> does, too.	4862	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
4736		4863	section.
4737	Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
4738	and continue to be present for the foreseeable future, so this is mostly a
4739	documentation change.
4740		4864
4741	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	4865	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4742		4866
4743	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	4867	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4744	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	4868	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4751		4875
4752	=over 4	4876	=over 4
4753		4877
4754	=item active	4878	=item active
4755		4879
4756	A watcher is active as long as it has been started (has been attached to	4880	A watcher is active as long as it has been started and not yet stopped.
4757	an event loop) but not yet stopped (disassociated from the event loop).	4881	See L<WATCHER STATES> for details.
4758		4882
4759	=item application	4883	=item application
4760		4884
4761	In this document, an application is whatever is using libev.	4885	In this document, an application is whatever is using libev.
		4886
		4887	=item backend
		4888
		4889	The part of the code dealing with the operating system interfaces.
4762		4890
4763	=item callback	4891	=item callback
4764		4892
4765	The address of a function that is called when some event has been	4893	The address of a function that is called when some event has been
4766	detected. Callbacks are being passed the event loop, the watcher that	4894	detected. Callbacks are being passed the event loop, the watcher that
4767	received the event, and the actual event bitset.	4895	received the event, and the actual event bitset.
4768		4896
4769	=item callback invocation	4897	=item callback/watcher invocation
4770		4898
4771	The act of calling the callback associated with a watcher.	4899	The act of calling the callback associated with a watcher.
4772		4900
4773	=item event	4901	=item event
4774		4902
…		…
4793	The model used to describe how an event loop handles and processes	4921	The model used to describe how an event loop handles and processes
4794	watchers and events.	4922	watchers and events.
4795		4923
4796	=item pending	4924	=item pending
4797		4925
4798	A watcher is pending as soon as the corresponding event has been detected,	4926	A watcher is pending as soon as the corresponding event has been
4799	and stops being pending as soon as the watcher will be invoked or its	4927	detected. See L<WATCHER STATES> for details.
4800	pending status is explicitly cleared by the application.
4801
4802	A watcher can be pending, but not active. Stopping a watcher also clears
4803	its pending status.
4804		4928
4805	=item real time	4929	=item real time
4806		4930
4807	The physical time that is observed. It is apparently strictly monotonic :)	4931	The physical time that is observed. It is apparently strictly monotonic :)
4808		4932
…		…
4815	=item watcher	4939	=item watcher
4816		4940
4817	A data structure that describes interest in certain events. Watchers need	4941	A data structure that describes interest in certain events. Watchers need
4818	to be started (attached to an event loop) before they can receive events.	4942	to be started (attached to an event loop) before they can receive events.
4819		4943
4820	=item watcher invocation
4821
4822	The act of calling the callback associated with a watcher.
4823
4824	=back	4944	=back
4825		4945
4826	=head1 AUTHOR	4946	=head1 AUTHOR
4827		4947
4828	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	4948	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.

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Comparing libev/ev.pod (file contents): Revision 1.305 by root, Thu Oct 14 05:07:04 2010 UTC vs. Revision 1.317 by root, Fri Oct 22 09:35:06 2010 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.305 by root, Thu Oct 14 05:07:04 2010 UTC vs.
Revision 1.317 by root, Fri Oct 22 09:35:06 2010 UTC