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

Comparing libev/ev.pod (file contents):
Revision 1.292 by sf-exg, Mon Mar 22 09:57:01 2010 UTC vs.
Revision 1.316 by root, Fri Oct 22 09:34:01 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
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
82		82
83	=head1 ABOUT LIBEV	83	=head1 ABOUT LIBEV
84		84
85	Libev is an event loop: you register interest in certain events (such as a	85	Libev is an event loop: you register interest in certain events (such as a
…		…
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 (somewhere	129	the (fractional) number of seconds since the (POSIX) epoch (in practise
130	near the beginning of 1970, details are complicated, don't ask). This	130	somewhere near the beginning of 1970, details are complicated, don't
131	type is called C<ev_tstamp>, which is what you should use too. It usually	131	ask). This type is called C<ev_tstamp>, which is what you should use
132	aliases to the C<double> type in C. When you need to do any calculations	132	too. It usually aliases to the C<double> type in C. When you need to do
133	on it, you should treat it as some floating point value. Unlike the name	133	any calculations on it, you should treat it as some floating point value.
		134
134	component C<stamp> might indicate, it is also used for time differences	135	Unlike the name component C<stamp> might indicate, it is also used for
135	throughout libev.	136	time differences (e.g. delays) throughout libev.
136		137
137	=head1 ERROR HANDLING	138	=head1 ERROR HANDLING
138		139
139	Libev knows three classes of errors: operating system errors, usage errors	140	Libev knows three classes of errors: operating system errors, usage errors
140	and internal errors (bugs).	141	and internal errors (bugs).
…		…
191	as this indicates an incompatible change. Minor versions are usually	192	as this indicates an incompatible change. Minor versions are usually
192	compatible to older versions, so a larger minor version alone is usually	193	compatible to older versions, so a larger minor version alone is usually
193	not a problem.	194	not a problem.
194		195
195	Example: Make sure we haven't accidentally been linked against the wrong	196	Example: Make sure we haven't accidentally been linked against the wrong
196	version.	197	version (note, however, that this will not detect ABI mismatches :).
197		198
198	assert (("libev version mismatch",	199	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	200	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	201	&& ev_version_minor () >= EV_VERSION_MINOR));
201		202
…		…
291		292
292	=back	293	=back
293		294
294	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	295	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
295		296
296	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
297	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
298	I<function>).	299	libev 3 had an C<ev_loop> function colliding with the struct name).
299		300
300	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
301	supports signals and child events, and dynamically created loops which do	302	supports signals and child events, and dynamically created event loops
302	not.	303	which do not.
303		304
304	=over 4	305	=over 4
305		306
306	=item struct ev_loop *ev_default_loop (unsigned int flags)	307	=item struct ev_loop *ev_default_loop (unsigned int flags)
307		308
…		…
438	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
439	I<different> file descriptors (even already closed ones, so one cannot	440	I<different> file descriptors (even already closed ones, so one cannot
440	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
441	on SMP systems). Libev tries to counter these spurious notifications by	442	on SMP systems). Libev tries to counter these spurious notifications by
442	employing an additional generation counter and comparing that against the	443	employing an additional generation counter and comparing that against the
443	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...).
444		447
445	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
446	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
447	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
448	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
…		…
603	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
604	earlier call to C<ev_loop_new>.	607	earlier call to C<ev_loop_new>.
605		608
606	=item ev_default_fork ()	609	=item ev_default_fork ()
607		610
608	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
609	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
610	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
611	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
612	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
613	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.
614		617
615	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
616	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
617	because some kernel interfaces cough I<kqueue> cough do funny things	620	because some kernel interfaces cough I<kqueue> cough do funny things
618	during fork.	621	during fork.
619		622
620	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
621	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
622	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
623	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).
624		629
625	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
626	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
627	quite nicely into a call to C<pthread_atfork>:	632	quite nicely into a call to C<pthread_atfork>:
628		633
…		…
640	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
641	otherwise.	646	otherwise.
642		647
643	=item unsigned int ev_iteration (loop)	648	=item unsigned int ev_iteration (loop)
644		649
645	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
646	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>
647	happily wraps around with enough iterations.	652	and happily wraps around with enough iterations.
648		653
649	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
650	"ticks" the number of loop iterations), as it roughly corresponds with	655	"ticks" the number of loop iterations), as it roughly corresponds with
651	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
652	prepare and check phases.	657	prepare and check phases.
653		658
654	=item unsigned int ev_depth (loop)	659	=item unsigned int ev_depth (loop)
655		660
656	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
657	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.
658		663
659	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
660	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),
661	in which case it is higher.	666	in which case it is higher.
662		667
663	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	668	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
664	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
665	ungentleman behaviour unless it's really convenient.	670	ungentleman-like behaviour unless it's really convenient.
666		671
667	=item unsigned int ev_backend (loop)	672	=item unsigned int ev_backend (loop)
668		673
669	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
670	use.	675	use.
…		…
679		684
680	=item ev_now_update (loop)	685	=item ev_now_update (loop)
681		686
682	Establishes the current time by querying the kernel, updating the time	687	Establishes the current time by querying the kernel, updating the time
683	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
684	is usually done automatically within C<ev_loop ()>.	689	is usually done automatically within C<ev_run ()>.
685		690
686	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
687	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
688	the current time is a good idea.	693	the current time is a good idea.
689		694
…		…
691		696
692	=item ev_suspend (loop)	697	=item ev_suspend (loop)
693		698
694	=item ev_resume (loop)	699	=item ev_resume (loop)
695		700
696	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
697	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.
698		703
699	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
700	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
701	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
702	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>
…		…
704	C<ev_resume> directly afterwards to resume timer processing.	709	C<ev_resume> directly afterwards to resume timer processing.
705		710
706	Effectively, all C<ev_timer> watchers will be delayed by the time spend	711	Effectively, all C<ev_timer> watchers will be delayed by the time spend
707	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	712	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
708	will be rescheduled (that is, they will lose any events that would have	713	will be rescheduled (that is, they will lose any events that would have
709	occured while suspended).	714	occurred while suspended).
710		715
711	After calling C<ev_suspend> you B<must not> call I<any> function on the	716	After calling C<ev_suspend> you B<must not> call I<any> function on the
712	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	717	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
713	without a previous call to C<ev_suspend>.	718	without a previous call to C<ev_suspend>.
714		719
715	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
716	event loop time (see C<ev_now_update>).	721	event loop time (see C<ev_now_update>).
717		722
718	=item ev_loop (loop, int flags)	723	=item ev_run (loop, int flags)
719		724
720	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
721	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
722	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>.
723		730
724	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
725	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.
726		734
727	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
728	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
729	finished (especially in interactive programs), but having a program	737	finished (especially in interactive programs), but having a program
730	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
731	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
732	beauty.	740	beauty.
733		741
734	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
735	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
736	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
737	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.
738		747
739	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
740	necessary) and will handle those and any already outstanding ones. It	749	necessary) and will handle those and any already outstanding ones. It
741	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
742	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
743	user-registered callback will be called), and will return after one	752	user-registered callback will be called), and will return after one
744	iteration of the loop.	753	iteration of the loop.
745		754
746	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
747	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
748	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
749	usually a better approach for this kind of thing.	758	usually a better approach for this kind of thing.
750		759
751	Here are the gory details of what C<ev_loop> does:	760	Here are the gory details of what C<ev_run> does:
752		761
		762	- Increment loop depth.
		763	- Reset the ev_break status.
753	- Before the first iteration, call any pending watchers.	764	- Before the first iteration, call any pending watchers.
		765	LOOP:
754	* If EVFLAG_FORKCHECK was used, check for a fork.	766	- If EVFLAG_FORKCHECK was used, check for a fork.
755	- 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.
756	- Queue and call all prepare watchers.	768	- Queue and call all prepare watchers.
		769	- If ev_break was called, goto FINISH.
757	- If we have been forked, detach and recreate the kernel state	770	- If we have been forked, detach and recreate the kernel state
758	as to not disturb the other process.	771	as to not disturb the other process.
759	- Update the kernel state with all outstanding changes.	772	- Update the kernel state with all outstanding changes.
760	- Update the "event loop time" (ev_now ()).	773	- Update the "event loop time" (ev_now ()).
761	- Calculate for how long to sleep or block, if at all	774	- Calculate for how long to sleep or block, if at all
762	(active idle watchers, EVLOOP_NONBLOCK or not having	775	(active idle watchers, EVRUN_NOWAIT or not having
763	any active watchers at all will result in not sleeping).	776	any active watchers at all will result in not sleeping).
764	- 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.
765	- Block the process, waiting for any events.	779	- Block the process, waiting for any events.
766	- Queue all outstanding I/O (fd) events.	780	- Queue all outstanding I/O (fd) events.
767	- 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.
768	- Queue all expired timers.	782	- Queue all expired timers.
769	- Queue all expired periodics.	783	- Queue all expired periodics.
770	- Unless any events are pending now, queue all idle watchers.	784	- Queue all idle watchers with priority higher than that of pending events.
771	- Queue all check watchers.	785	- Queue all check watchers.
772	- 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).
773	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
774	be handled here by queueing them when their watcher gets executed.	788	be handled here by queueing them when their watcher gets executed.
775	- 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
776	were used, or there are no active watchers, return, otherwise	790	were used, or there are no active watchers, goto FINISH, otherwise
777	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.
778		796
779	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
780	anymore.	798	anymore.
781		799
782	... queue jobs here, make sure they register event watchers as long	800	... queue jobs here, make sure they register event watchers as long
783	... 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..)
784	ev_loop (my_loop, 0);	802	ev_run (my_loop, 0);
785	... jobs done or somebody called unloop. yeah!	803	... jobs done or somebody called unloop. yeah!
786		804
787	=item ev_unloop (loop, how)	805	=item ev_break (loop, how)
788		806
789	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
790	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
791	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
792	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.
793		811
794	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.
795		813
796	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	814	It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO##
797		815
798	=item ev_ref (loop)	816	=item ev_ref (loop)
799		817
800	=item ev_unref (loop)	818	=item ev_unref (loop)
801		819
802	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
803	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
804	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.
805		823
806	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
807	unregister, but that nevertheless should not keep C<ev_loop> from	825	unregister, but that nevertheless should not keep C<ev_run> from
808	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>
809	before stopping it.	827	before stopping it.
810		828
811	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
812	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
813	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
814	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
815	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
816	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
817	before, respectively. Note also that libev might stop watchers itself	835	before, respectively. Note also that libev might stop watchers itself
818	(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>
819	in the callback).	837	in the callback).
820		838
821	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>
822	running when nothing else is active.	840	running when nothing else is active.
823		841
824	ev_signal exitsig;	842	ev_signal exitsig;
825	ev_signal_init (&exitsig, sig_cb, SIGINT);	843	ev_signal_init (&exitsig, sig_cb, SIGINT);
826	ev_signal_start (loop, &exitsig);	844	ev_signal_start (loop, &exitsig);
…		…
871	usually doesn't make much sense to set it to a lower value than C<0.01>,	889	usually doesn't make much sense to set it to a lower value than C<0.01>,
872	as this approaches the timing granularity of most systems. Note that if	890	as this approaches the timing granularity of most systems. Note that if
873	you do transactions with the outside world and you can't increase the	891	you do transactions with the outside world and you can't increase the
874	parallelity, then this setting will limit your transaction rate (if you	892	parallelity, then this setting will limit your transaction rate (if you
875	need to poll once per transaction and the I/O collect interval is 0.01,	893	need to poll once per transaction and the I/O collect interval is 0.01,
876	then you can't do more than 100 transations per second).	894	then you can't do more than 100 transactions per second).
877		895
878	Setting the I<timeout collect interval> can improve the opportunity for	896	Setting the I<timeout collect interval> can improve the opportunity for
879	saving power, as the program will "bundle" timer callback invocations that	897	saving power, as the program will "bundle" timer callback invocations that
880	are "near" in time together, by delaying some, thus reducing the number of	898	are "near" in time together, by delaying some, thus reducing the number of
881	times the process sleeps and wakes up again. Another useful technique to	899	times the process sleeps and wakes up again. Another useful technique to
…		…
889	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	907	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
890		908
891	=item ev_invoke_pending (loop)	909	=item ev_invoke_pending (loop)
892		910
893	This call will simply invoke all pending watchers while resetting their	911	This call will simply invoke all pending watchers while resetting their
894	pending state. Normally, C<ev_loop> does this automatically when required,	912	pending state. Normally, C<ev_run> does this automatically when required,
895	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).
896		918
897	=item int ev_pending_count (loop)	919	=item int ev_pending_count (loop)
898		920
899	Returns the number of pending watchers - zero indicates that no watchers	921	Returns the number of pending watchers - zero indicates that no watchers
900	are pending.	922	are pending.
901		923
902	=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))
903		925
904	This overrides the invoke pending functionality of the loop: Instead of	926	This overrides the invoke pending functionality of the loop: Instead of
905	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
906	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
907	invoke the actual watchers inside another context (another thread etc.).	929	invoke the actual watchers inside another context (another thread etc.).
908		930
909	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
910	callback.	932	callback.
…		…
913		935
914	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
915	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
916	each call to a libev function.	938	each call to a libev function.
917		939
918	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
919	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
920	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
921	and I<acquire> callbacks on the loop.	943	I<release> and I<acquire> callbacks on the loop.
922		944
923	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
924	suspended waiting for new events, and C<acquire> is called just	946	suspended waiting for new events, and C<acquire> is called just
925	afterwards.	947	afterwards.
926		948
…		…
929		951
930	While event loop modifications are allowed between invocations of	952	While event loop modifications are allowed between invocations of
931	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
932	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
933	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
934	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
935	to take note of any changes you made.	957	to take note of any changes you made.
936		958
937	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
938	invocations of C<release> and C<acquire>.	960	invocations of C<release> and C<acquire>.
939		961
940	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
941	document.	963	document.
942		964
…		…
951	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,
952	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
953	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
954	any other purpose as well.	976	any other purpose as well.
955		977
956	=item ev_loop_verify (loop)	978	=item ev_verify (loop)
957		979
958	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
959	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
960	through all internal structures and checks them for validity. If anything	982	through all internal structures and checks them for validity. If anything
961	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
…		…
972		994
973	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
974	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
975	watchers and C<ev_io_start> for I/O watchers.	997	watchers and C<ev_io_start> for I/O watchers.
976		998
977	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
978	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
979	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:
980		1003
981	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)
982	{	1005	{
983	ev_io_stop (w);	1006	ev_io_stop (w);
984	ev_unloop (loop, EVUNLOOP_ALL);	1007	ev_break (loop, EVBREAK_ALL);
985	}	1008	}
986		1009
987	struct ev_loop *loop = ev_default_loop (0);	1010	struct ev_loop *loop = ev_default_loop (0);
988		1011
989	ev_io stdin_watcher;	1012	ev_io stdin_watcher;
990		1013
991	ev_init (&stdin_watcher, my_cb);	1014	ev_init (&stdin_watcher, my_cb);
992	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1015	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
993	ev_io_start (loop, &stdin_watcher);	1016	ev_io_start (loop, &stdin_watcher);
994		1017
995	ev_loop (loop, 0);	1018	ev_run (loop, 0);
996		1019
997	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
998	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
999	stack).	1022	stack).
1000		1023
1001	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>
1002	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).
1003		1026
1004	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
1005	(watcher *, callback)>, which expects a callback to be provided. This	1028	*, callback)>, which expects a callback to be provided. This callback is
1006	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
1007	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
1008	is readable and/or writable).	1031	and/or writable).
1009		1032
1010	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 *, ...) >>
1011	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
1012	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<<
1013	ev_TYPE_init (watcher *, callback, ...) >>.	1036	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1064		1087
1065	=item C<EV_PREPARE>	1088	=item C<EV_PREPARE>
1066		1089
1067	=item C<EV_CHECK>	1090	=item C<EV_CHECK>
1068		1091
1069	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
1070	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
1071	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
1072	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
1073	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
1074	(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
1075	C<ev_loop> from blocking).	1098	C<ev_run> from blocking).
1076		1099
1077	=item C<EV_EMBED>	1100	=item C<EV_EMBED>
1078		1101
1079	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.
1080		1103
…		…
1108	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
1109	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
1110	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
1111	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
1112	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.
1113		1195
1114	=back	1196	=back
1115		1197
1116	=head2 GENERIC WATCHER FUNCTIONS	1198	=head2 GENERIC WATCHER FUNCTIONS
1117		1199
…		…
1379		1461
1380	For example, to emulate how many other event libraries handle priorities,	1462	For example, to emulate how many other event libraries handle priorities,
1381	you can associate an C<ev_idle> watcher to each such watcher, and in	1463	you can associate an C<ev_idle> watcher to each such watcher, and in
1382	the normal watcher callback, you just start the idle watcher. The real	1464	the normal watcher callback, you just start the idle watcher. The real
1383	processing is done in the idle watcher callback. This causes libev to	1465	processing is done in the idle watcher callback. This causes libev to
1384	continously poll and process kernel event data for the watcher, but when	1466	continuously poll and process kernel event data for the watcher, but when
1385	the lock-out case is known to be rare (which in turn is rare :), this is	1467	the lock-out case is known to be rare (which in turn is rare :), this is
1386	workable.	1468	workable.
1387		1469
1388	Usually, however, the lock-out model implemented that way will perform	1470	Usually, however, the lock-out model implemented that way will perform
1389	miserably under the type of load it was designed to handle. In that case,	1471	miserably under the type of load it was designed to handle. In that case,
…		…
1403	{	1485	{
1404	// stop the I/O watcher, we received the event, but	1486	// stop the I/O watcher, we received the event, but
1405	// are not yet ready to handle it.	1487	// are not yet ready to handle it.
1406	ev_io_stop (EV_A_ w);	1488	ev_io_stop (EV_A_ w);
1407		1489
1408	// start the idle watcher to ahndle the actual event.	1490	// start the idle watcher to handle the actual event.
1409	// it will not be executed as long as other watchers	1491	// it will not be executed as long as other watchers
1410	// with the default priority are receiving events.	1492	// with the default priority are receiving events.
1411	ev_idle_start (EV_A_ &idle);	1493	ev_idle_start (EV_A_ &idle);
1412	}	1494	}
1413		1495
…		…
1467		1549
1468	If you cannot use non-blocking mode, then force the use of a	1550	If you cannot use non-blocking mode, then force the use of a
1469	known-to-be-good backend (at the time of this writing, this includes only	1551	known-to-be-good backend (at the time of this writing, this includes only
1470	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1552	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1471	descriptors for which non-blocking operation makes no sense (such as	1553	descriptors for which non-blocking operation makes no sense (such as
1472	files) - libev doesn't guarentee any specific behaviour in that case.	1554	files) - libev doesn't guarantee any specific behaviour in that case.
1473		1555
1474	Another thing you have to watch out for is that it is quite easy to	1556	Another thing you have to watch out for is that it is quite easy to
1475	receive "spurious" readiness notifications, that is your callback might	1557	receive "spurious" readiness notifications, that is your callback might
1476	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1558	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1477	because there is no data. Not only are some backends known to create a	1559	because there is no data. Not only are some backends known to create a
…		…
1621	...	1703	...
1622	struct ev_loop *loop = ev_default_init (0);	1704	struct ev_loop *loop = ev_default_init (0);
1623	ev_io stdin_readable;	1705	ev_io stdin_readable;
1624	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);
1625	ev_io_start (loop, &stdin_readable);	1707	ev_io_start (loop, &stdin_readable);
1626	ev_loop (loop, 0);	1708	ev_run (loop, 0);
1627		1709
1628		1710
1629	=head2 C<ev_timer> - relative and optionally repeating timeouts	1711	=head2 C<ev_timer> - relative and optionally repeating timeouts
1630		1712
1631	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
…		…
1640	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
1641	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
1642	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
1643	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
1644	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
1645	no longer true when a callback calls C<ev_loop> recursively).	1727	no longer true when a callback calls C<ev_run> recursively).
1646		1728
1647	=head3 Be smart about timeouts	1729	=head3 Be smart about timeouts
1648		1730
1649	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
1650	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,
…		…
1736	ev_tstamp timeout = last_activity + 60.;	1818	ev_tstamp timeout = last_activity + 60.;
1737		1819
1738	// if last_activity + 60. is older than now, we did time out	1820	// if last_activity + 60. is older than now, we did time out
1739	if (timeout < now)	1821	if (timeout < now)
1740	{	1822	{
1741	// timeout occured, take action	1823	// timeout occurred, take action
1742	}	1824	}
1743	else	1825	else
1744	{	1826	{
1745	// callback was invoked, but there was some activity, re-arm	1827	// callback was invoked, but there was some activity, re-arm
1746	// the watcher to fire in last_activity + 60, which is	1828	// the watcher to fire in last_activity + 60, which is
…		…
1773	callback (loop, timer, EV_TIMER);	1855	callback (loop, timer, EV_TIMER);
1774		1856
1775	And when there is some activity, simply store the current time in	1857	And when there is some activity, simply store the current time in
1776	C<last_activity>, no libev calls at all:	1858	C<last_activity>, no libev calls at all:
1777		1859
1778	last_actiivty = ev_now (loop);	1860	last_activity = ev_now (loop);
1779		1861
1780	This technique is slightly more complex, but in most cases where the	1862	This technique is slightly more complex, but in most cases where the
1781	time-out is unlikely to be triggered, much more efficient.	1863	time-out is unlikely to be triggered, much more efficient.
1782		1864
1783	Changing the timeout is trivial as well (if it isn't hard-coded in the	1865	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1821		1903
1822	=head3 The special problem of time updates	1904	=head3 The special problem of time updates
1823		1905
1824	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
1825	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
1826	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
1827	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
1828	lots of events in one iteration.	1910	lots of events in one iteration.
1829		1911
1830	The relative timeouts are calculated relative to the C<ev_now ()>	1912	The relative timeouts are calculated relative to the C<ev_now ()>
1831	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
…		…
1948	}	2030	}
1949		2031
1950	ev_timer mytimer;	2032	ev_timer mytimer;
1951	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 */
1952	ev_timer_again (&mytimer); /* start timer */	2034	ev_timer_again (&mytimer); /* start timer */
1953	ev_loop (loop, 0);	2035	ev_run (loop, 0);
1954		2036
1955	// 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":
1956	// reset the timeout to start ticking again at 10 seconds	2038	// reset the timeout to start ticking again at 10 seconds
1957	ev_timer_again (&mytimer);	2039	ev_timer_again (&mytimer);
1958		2040
…		…
1984		2066
1985	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
1986	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
1987	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
1988	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
1989	(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).
1990		2072
1991	=head3 Watcher-Specific Functions and Data Members	2073	=head3 Watcher-Specific Functions and Data Members
1992		2074
1993	=over 4	2075	=over 4
1994		2076
…		…
2122	Example: Call a callback every hour, or, more precisely, whenever the	2204	Example: Call a callback every hour, or, more precisely, whenever the
2123	system time is divisible by 3600. The callback invocation times have	2205	system time is divisible by 3600. The callback invocation times have
2124	potentially a lot of jitter, but good long-term stability.	2206	potentially a lot of jitter, but good long-term stability.
2125		2207
2126	static void	2208	static void
2127	clock_cb (struct ev_loop loop, ev_io w, int revents)	2209	clock_cb (struct ev_loop loop, ev_periodic w, int revents)
2128	{	2210	{
2129	... its now a full hour (UTC, or TAI or whatever your clock follows)	2211	... its now a full hour (UTC, or TAI or whatever your clock follows)
2130	}	2212	}
2131		2213
2132	ev_periodic hourly_tick;	2214	ev_periodic hourly_tick;
…		…
2232	Example: Try to exit cleanly on SIGINT.	2314	Example: Try to exit cleanly on SIGINT.
2233		2315
2234	static void	2316	static void
2235	sigint_cb (struct ev_loop loop, ev_signal w, int revents)	2317	sigint_cb (struct ev_loop loop, ev_signal w, int revents)
2236	{	2318	{
2237	ev_unloop (loop, EVUNLOOP_ALL);	2319	ev_break (loop, EVBREAK_ALL);
2238	}	2320	}
2239		2321
2240	ev_signal signal_watcher;	2322	ev_signal signal_watcher;
2241	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2323	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2242	ev_signal_start (loop, &signal_watcher);	2324	ev_signal_start (loop, &signal_watcher);
…		…
2628		2710
2629	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:
2630	prepare watchers get invoked before the process blocks and check watchers	2712	prepare watchers get invoked before the process blocks and check watchers
2631	afterwards.	2713	afterwards.
2632		2714
2633	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
2634	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>
2635	watchers. Other loops than the current one are fine, however. The	2717	watchers. Other loops than the current one are fine, however. The
2636	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
2637	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,
2638	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
…		…
2806		2888
2807	if (timeout >= 0)	2889	if (timeout >= 0)
2808	// create/start timer	2890	// create/start timer
2809		2891
2810	// poll	2892	// poll
2811	ev_loop (EV_A_ 0);	2893	ev_run (EV_A_ 0);
2812		2894
2813	// stop timer again	2895	// stop timer again
2814	if (timeout >= 0)	2896	if (timeout >= 0)
2815	ev_timer_stop (EV_A_ &to);	2897	ev_timer_stop (EV_A_ &to);
2816		2898
…		…
2894	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).
2895		2977
2896	=item ev_embed_sweep (loop, ev_embed *)	2978	=item ev_embed_sweep (loop, ev_embed *)
2897		2979
2898	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
2899	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
2900	appropriate way for embedded loops.	2982	appropriate way for embedded loops.
2901		2983
2902	=item struct ev_loop *other [read-only]	2984	=item struct ev_loop *other [read-only]
2903		2985
2904	The embedded event loop.	2986	The embedded event loop.
…		…
2964	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3046	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2965	handlers will be invoked, too, of course.	3047	handlers will be invoked, too, of course.
2966		3048
2967	=head3 The special problem of life after fork - how is it possible?	3049	=head3 The special problem of life after fork - how is it possible?
2968		3050
2969	Most uses of C<fork()> consist of forking, then some simple calls to ste	3051	Most uses of C<fork()> consist of forking, then some simple calls to set
2970	up/change the process environment, followed by a call to C<exec()>. This	3052	up/change the process environment, followed by a call to C<exec()>. This
2971	sequence should be handled by libev without any problems.	3053	sequence should be handled by libev without any problems.
2972		3054
2973	This changes when the application actually wants to do event handling	3055	This changes when the application actually wants to do event handling
2974	in the child, or both parent in child, in effect "continuing" after the	3056	in the child, or both parent in child, in effect "continuing" after the
…		…
3008	believe me.	3090	believe me.
3009		3091
3010	=back	3092	=back
3011		3093
3012		3094
3013	=head2 C<ev_async> - how to wake up another event loop	3095	=head2 C<ev_async> - how to wake up an event loop
3014		3096
3015	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
3016	asynchronous sources such as signal handlers (as opposed to multiple event	3098	asynchronous sources such as signal handlers (as opposed to multiple event
3017	loops - those are of course safe to use in different threads).	3099	loops - those are of course safe to use in different threads).
3018		3100
3019	Sometimes, however, you need to wake up another event loop you do not	3101	Sometimes, however, you need to wake up an event loop you do not control,
3020	control, for example because it belongs to another thread. This is what	3102	for example because it belongs to another thread. This is what C<ev_async>
3021	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3103	watchers do: as long as the C<ev_async> watcher is active, you can signal
3022	can signal it by calling C<ev_async_send>, which is thread- and signal	3104	it by calling C<ev_async_send>, which is thread- and signal safe.
3023	safe.
3024		3105
3025	This functionality is very similar to C<ev_signal> watchers, as signals,	3106	This functionality is very similar to C<ev_signal> watchers, as signals,
3026	too, are asynchronous in nature, and signals, too, will be compressed	3107	too, are asynchronous in nature, and signals, too, will be compressed
3027	(i.e. the number of callback invocations may be less than the number of	3108	(i.e. the number of callback invocations may be less than the number of
3028	C<ev_async_sent> calls).	3109	C<ev_async_sent> calls).
…		…
3340	myclass obj;	3421	myclass obj;
3341	ev::io iow;	3422	ev::io iow;
3342	iow.set <myclass, &myclass::io_cb> (&obj);	3423	iow.set <myclass, &myclass::io_cb> (&obj);
3343		3424
3344	=item w->set (object *)	3425	=item w->set (object *)
3345
3346	This is an B<experimental> feature that might go away in a future version.
3347		3426
3348	This is a variation of a method callback - leaving out the method to call	3427	This is a variation of a method callback - leaving out the method to call
3349	will default the method to C<operator ()>, which makes it possible to use	3428	will default the method to C<operator ()>, which makes it possible to use
3350	functor objects without having to manually specify the C<operator ()> all	3429	functor objects without having to manually specify the C<operator ()> all
3351	the time. Incidentally, you can then also leave out the template argument	3430	the time. Incidentally, you can then also leave out the template argument
…		…
3391	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
3392	do this when the watcher is inactive (and not pending either).	3471	do this when the watcher is inactive (and not pending either).
3393		3472
3394	=item w->set ([arguments])	3473	=item w->set ([arguments])
3395		3474
3396	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
3397	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
3398	automatically stopped and restarted when reconfiguring it with this	3477	C counterpart, an active watcher gets automatically stopped and restarted
3399	method.	3478	when reconfiguring it with this method.
3400		3479
3401	=item w->start ()	3480	=item w->start ()
3402		3481
3403	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
3404	constructor already stores the event loop.	3483	constructor already stores the event loop.
3405		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
3406	=item w->stop ()	3491	=item w->stop ()
3407		3492
3408	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.
3409		3494
3410	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3495	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3422		3507
3423	=back	3508	=back
3424		3509
3425	=back	3510	=back
3426		3511
3427	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
3428	the constructor.	3513	watchers in the constructor.
3429		3514
3430	class myclass	3515	class myclass
3431	{	3516	{
3432	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);
3433	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3519	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3434		3520
3435	myclass (int fd)	3521	myclass (int fd)
3436	{	3522	{
3437	io .set <myclass, &myclass::io_cb > (this);	3523	io .set <myclass, &myclass::io_cb > (this);
		3524	io2 .set <myclass, &myclass::io2_cb > (this);
3438	idle.set <myclass, &myclass::idle_cb> (this);	3525	idle.set <myclass, &myclass::idle_cb> (this);
3439		3526
3440	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
3441	}	3531	}
3442	};	3532	};
3443		3533
3444		3534
3445	=head1 OTHER LANGUAGE BINDINGS	3535	=head1 OTHER LANGUAGE BINDINGS
…		…
3519	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,
3520	C<EV_A_> is used when other arguments are following. Example:	3610	C<EV_A_> is used when other arguments are following. Example:
3521		3611
3522	ev_unref (EV_A);	3612	ev_unref (EV_A);
3523	ev_timer_add (EV_A_ watcher);	3613	ev_timer_add (EV_A_ watcher);
3524	ev_loop (EV_A_ 0);	3614	ev_run (EV_A_ 0);
3525		3615
3526	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,
3527	which is often provided by the following macro.	3617	which is often provided by the following macro.
3528		3618
3529	=item C<EV_P>, C<EV_P_>	3619	=item C<EV_P>, C<EV_P_>
…		…
3569	}	3659	}
3570		3660
3571	ev_check check;	3661	ev_check check;
3572	ev_check_init (&check, check_cb);	3662	ev_check_init (&check, check_cb);
3573	ev_check_start (EV_DEFAULT_ &check);	3663	ev_check_start (EV_DEFAULT_ &check);
3574	ev_loop (EV_DEFAULT_ 0);	3664	ev_run (EV_DEFAULT_ 0);
3575		3665
3576	=head1 EMBEDDING	3666	=head1 EMBEDDING
3577		3667
3578	Libev can (and often is) directly embedded into host	3668	Libev can (and often is) directly embedded into host
3579	applications. Examples of applications that embed it include the Deliantra	3669	applications. Examples of applications that embed it include the Deliantra
…		…
3670	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
3671	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
3672	settings.	3762	settings.
3673		3763
3674	=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.
3675		3781
3676	=item EV_STANDALONE (h)	3782	=item EV_STANDALONE (h)
3677		3783
3678	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
3679	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
…		…
3886	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,	3992	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
3887	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.	3993	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3888		3994
3889	If undefined or defined to be C<1> (and the platform supports it), then	3995	If undefined or defined to be C<1> (and the platform supports it), then
3890	the respective watcher type is supported. If defined to be C<0>, then it	3996	the respective watcher type is supported. If defined to be C<0>, then it
3891	is not. Disabling watcher types mainly saves codesize.	3997	is not. Disabling watcher types mainly saves code size.
3892		3998
3893	=item EV_FEATURES	3999	=item EV_FEATURES
3894		4000
3895	If you need to shave off some kilobytes of code at the expense of some	4001	If you need to shave off some kilobytes of code at the expense of some
3896	speed (but with the full API), you can define this symbol to request	4002	speed (but with the full API), you can define this symbol to request
…		…
3916		4022
3917	=item C<1> - faster/larger code	4023	=item C<1> - faster/larger code
3918		4024
3919	Use larger code to speed up some operations.	4025	Use larger code to speed up some operations.
3920		4026
3921	Currently this is used to override some inlining decisions (enlarging the roughly	4027	Currently this is used to override some inlining decisions (enlarging the
3922	30% code size on amd64.	4028	code size by roughly 30% on amd64).
3923		4029
3924	When optimising for size, use of compiler flags such as C<-Os> with	4030	When optimising for size, use of compiler flags such as C<-Os> with
3925	gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of	4031	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
3926	assertions.	4032	assertions.
3927		4033
3928	=item C<2> - faster/larger data structures	4034	=item C<2> - faster/larger data structures
3929		4035
3930	Replaces the small 2-heap for timer management by a faster 4-heap, larger	4036	Replaces the small 2-heap for timer management by a faster 4-heap, larger
3931	hash table sizes and so on. This will usually further increase codesize	4037	hash table sizes and so on. This will usually further increase code size
3932	and can additionally have an effect on the size of data structures at	4038	and can additionally have an effect on the size of data structures at
3933	runtime.	4039	runtime.
3934		4040
3935	=item C<4> - full API configuration	4041	=item C<4> - full API configuration
3936		4042
…		…
3973	I/O watcher then might come out at only 5Kb.	4079	I/O watcher then might come out at only 5Kb.
3974		4080
3975	=item EV_AVOID_STDIO	4081	=item EV_AVOID_STDIO
3976		4082
3977	If this is set to C<1> at compiletime, then libev will avoid using stdio	4083	If this is set to C<1> at compiletime, then libev will avoid using stdio
3978	functions (printf, scanf, perror etc.). This will increase the codesize	4084	functions (printf, scanf, perror etc.). This will increase the code size
3979	somewhat, but if your program doesn't otherwise depend on stdio and your	4085	somewhat, but if your program doesn't otherwise depend on stdio and your
3980	libc allows it, this avoids linking in the stdio library which is quite	4086	libc allows it, this avoids linking in the stdio library which is quite
3981	big.	4087	big.
3982		4088
3983	Note that error messages might become less precise when this option is	4089	Note that error messages might become less precise when this option is
…		…
3987		4093
3988	The highest supported signal number, +1 (or, the number of	4094	The highest supported signal number, +1 (or, the number of
3989	signals): Normally, libev tries to deduce the maximum number of signals	4095	signals): Normally, libev tries to deduce the maximum number of signals
3990	automatically, but sometimes this fails, in which case it can be	4096	automatically, but sometimes this fails, in which case it can be
3991	specified. Also, using a lower number than detected (C<32> should be	4097	specified. Also, using a lower number than detected (C<32> should be
3992	good for about any system in existance) can save some memory, as libev	4098	good for about any system in existence) can save some memory, as libev
3993	statically allocates some 12-24 bytes per signal number.	4099	statically allocates some 12-24 bytes per signal number.
3994		4100
3995	=item EV_PID_HASHSIZE	4101	=item EV_PID_HASHSIZE
3996		4102
3997	C<ev_child> watchers use a small hash table to distribute workload by	4103	C<ev_child> watchers use a small hash table to distribute workload by
…		…
4029	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
4030	will be C<0>.	4136	will be C<0>.
4031		4137
4032	=item EV_VERIFY	4138	=item EV_VERIFY
4033		4139
4034	Controls how much internal verification (see C<ev_loop_verify ()>) will	4140	Controls how much internal verification (see C<ev_verify ()>) will
4035	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
4036	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
4037	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
4038	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
4039	verification code will be called very frequently, which will slow down	4145	verification code will be called very frequently, which will slow down
…		…
4043	will be C<0>.	4149	will be C<0>.
4044		4150
4045	=item EV_COMMON	4151	=item EV_COMMON
4046		4152
4047	By default, all watchers have a C<void *data> member. By redefining	4153	By default, all watchers have a C<void *data> member. By redefining
4048	this macro to a something else you can include more and other types of	4154	this macro to something else you can include more and other types of
4049	members. You have to define it each time you include one of the files,	4155	members. You have to define it each time you include one of the files,
4050	though, and it must be identical each time.	4156	though, and it must be identical each time.
4051		4157
4052	For example, the perl EV module uses something like this:	4158	For example, the perl EV module uses something like this:
4053		4159
…		…
4254	userdata *u = ev_userdata (EV_A);	4360	userdata *u = ev_userdata (EV_A);
4255	pthread_mutex_lock (&u->lock);	4361	pthread_mutex_lock (&u->lock);
4256	}	4362	}
4257		4363
4258	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
4259	into C<ev_loop>:	4365	into C<ev_run>:
4260		4366
4261	void *	4367	void *
4262	l_run (void *thr_arg)	4368	l_run (void *thr_arg)
4263	{	4369	{
4264	struct ev_loop loop = (struct ev_loop )thr_arg;	4370	struct ev_loop loop = (struct ev_loop )thr_arg;
4265		4371
4266	l_acquire (EV_A);	4372	l_acquire (EV_A);
4267	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4373	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4268	ev_loop (EV_A_ 0);	4374	ev_run (EV_A_ 0);
4269	l_release (EV_A);	4375	l_release (EV_A);
4270		4376
4271	return 0;	4377	return 0;
4272	}	4378	}
4273		4379
…		…
4325		4431
4326	=head3 COROUTINES	4432	=head3 COROUTINES
4327		4433
4328	Libev is very accommodating to coroutines ("cooperative threads"):	4434	Libev is very accommodating to coroutines ("cooperative threads"):
4329	libev fully supports nesting calls to its functions from different	4435	libev fully supports nesting calls to its functions from different
4330	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
4331	different coroutines, and switch freely between both coroutines running	4437	different coroutines, and switch freely between both coroutines running
4332	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
4333	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.
4334		4440
4335	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
4336	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
4337	they do not call any callbacks.	4443	they do not call any callbacks.
4338		4444
4339	=head2 COMPILER WARNINGS	4445	=head2 COMPILER WARNINGS
4340		4446
4341	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
…		…
4352	maintainable.	4458	maintainable.
4353		4459
4354	And of course, some compiler warnings are just plain stupid, or simply	4460	And of course, some compiler warnings are just plain stupid, or simply
4355	wrong (because they don't actually warn about the condition their message	4461	wrong (because they don't actually warn about the condition their message
4356	seems to warn about). For example, certain older gcc versions had some	4462	seems to warn about). For example, certain older gcc versions had some
4357	warnings that resulted an extreme number of false positives. These have	4463	warnings that resulted in an extreme number of false positives. These have
4358	been fixed, but some people still insist on making code warn-free with	4464	been fixed, but some people still insist on making code warn-free with
4359	such buggy versions.	4465	such buggy versions.
4360		4466
4361	While libev is written to generate as few warnings as possible,	4467	While libev is written to generate as few warnings as possible,
4362	"warn-free" code is not a goal, and it is recommended not to build libev	4468	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4398	I suggest using suppression lists.	4504	I suggest using suppression lists.
4399		4505
4400		4506
4401	=head1 PORTABILITY NOTES	4507	=head1 PORTABILITY NOTES
4402		4508
		4509	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4510
		4511	GNU/Linux is the only common platform that supports 64 bit file/large file
		4512	interfaces but I<disables> them by default.
		4513
		4514	That means that libev compiled in the default environment doesn't support
		4515	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4516
		4517	Unfortunately, many programs try to work around this GNU/Linux issue
		4518	by enabling the large file API, which makes them incompatible with the
		4519	standard libev compiled for their system.
		4520
		4521	Likewise, libev cannot enable the large file API itself as this would
		4522	suddenly make it incompatible to the default compile time environment,
		4523	i.e. all programs not using special compile switches.
		4524
		4525	=head2 OS/X AND DARWIN BUGS
		4526
		4527	The whole thing is a bug if you ask me - basically any system interface
		4528	you touch is broken, whether it is locales, poll, kqueue or even the
		4529	OpenGL drivers.
		4530
		4531	=head3 C<kqueue> is buggy
		4532
		4533	The kqueue syscall is broken in all known versions - most versions support
		4534	only sockets, many support pipes.
		4535
		4536	Libev tries to work around this by not using C<kqueue> by default on this
		4537	rotten platform, but of course you can still ask for it when creating a
		4538	loop - embedding a socket-only kqueue loop into a select-based one is
		4539	probably going to work well.
		4540
		4541	=head3 C<poll> is buggy
		4542
		4543	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4544	implementation by something calling C<kqueue> internally around the 10.5.6
		4545	release, so now C<kqueue> I<and> C<poll> are broken.
		4546
		4547	Libev tries to work around this by not using C<poll> by default on
		4548	this rotten platform, but of course you can still ask for it when creating
		4549	a loop.
		4550
		4551	=head3 C<select> is buggy
		4552
		4553	All that's left is C<select>, and of course Apple found a way to fuck this
		4554	one up as well: On OS/X, C<select> actively limits the number of file
		4555	descriptors you can pass in to 1024 - your program suddenly crashes when
		4556	you use more.
		4557
		4558	There is an undocumented "workaround" for this - defining
		4559	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4560	work on OS/X.
		4561
		4562	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4563
		4564	=head3 C<errno> reentrancy
		4565
		4566	The default compile environment on Solaris is unfortunately so
		4567	thread-unsafe that you can't even use components/libraries compiled
		4568	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4569	defined by default. A valid, if stupid, implementation choice.
		4570
		4571	If you want to use libev in threaded environments you have to make sure
		4572	it's compiled with C<_REENTRANT> defined.
		4573
		4574	=head3 Event port backend
		4575
		4576	The scalable event interface for Solaris is called "event
		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
		4579	a large number of spurious wakeups, make sure you have all the relevant
		4580	and latest kernel patches applied. No, I don't know which ones, but there
		4581	are multiple ones to apply, and afterwards, event ports actually work
		4582	great.
		4583
		4584	If you can't get it to work, you can try running the program by setting
		4585	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4586	C<select> backends.
		4587
		4588	=head2 AIX POLL BUG
		4589
		4590	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4591	this by trying to avoid the poll backend altogether (i.e. it's not even
		4592	compiled in), which normally isn't a big problem as C<select> works fine
		4593	with large bitsets on AIX, and AIX is dead anyway.
		4594
4403	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4595	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4596
		4597	=head3 General issues
4404		4598
4405	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4599	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4406	requires, and its I/O model is fundamentally incompatible with the POSIX	4600	requires, and its I/O model is fundamentally incompatible with the POSIX
4407	model. Libev still offers limited functionality on this platform in	4601	model. Libev still offers limited functionality on this platform in
4408	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4602	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4409	descriptors. This only applies when using Win32 natively, not when using	4603	descriptors. This only applies when using Win32 natively, not when using
4410	e.g. cygwin.	4604	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4605	as every compielr comes with a slightly differently broken/incompatible
		4606	environment.
4411		4607
4412	Lifting these limitations would basically require the full	4608	Lifting these limitations would basically require the full
4413	re-implementation of the I/O system. If you are into these kinds of	4609	re-implementation of the I/O system. If you are into this kind of thing,
4414	things, then note that glib does exactly that for you in a very portable	4610	then note that glib does exactly that for you in a very portable way (note
4415	way (note also that glib is the slowest event library known to man).	4611	also that glib is the slowest event library known to man).
4416		4612
4417	There is no supported compilation method available on windows except	4613	There is no supported compilation method available on windows except
4418	embedding it into other applications.	4614	embedding it into other applications.
4419		4615
4420	Sensible signal handling is officially unsupported by Microsoft - libev	4616	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4448	you do I<not> compile the F<ev.c> or any other embedded source files!):	4644	you do I<not> compile the F<ev.c> or any other embedded source files!):
4449		4645
4450	#include "evwrap.h"	4646	#include "evwrap.h"
4451	#include "ev.c"	4647	#include "ev.c"
4452		4648
4453	=over 4
4454
4455	=item The winsocket select function	4649	=head3 The winsocket C<select> function
4456		4650
4457	The winsocket C<select> function doesn't follow POSIX in that it	4651	The winsocket C<select> function doesn't follow POSIX in that it
4458	requires socket I<handles> and not socket I<file descriptors> (it is	4652	requires socket I<handles> and not socket I<file descriptors> (it is
4459	also extremely buggy). This makes select very inefficient, and also	4653	also extremely buggy). This makes select very inefficient, and also
4460	requires a mapping from file descriptors to socket handles (the Microsoft	4654	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4469	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4663	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4470		4664
4471	Note that winsockets handling of fd sets is O(n), so you can easily get a	4665	Note that winsockets handling of fd sets is O(n), so you can easily get a
4472	complexity in the O(n²) range when using win32.	4666	complexity in the O(n²) range when using win32.
4473		4667
4474	=item Limited number of file descriptors	4668	=head3 Limited number of file descriptors
4475		4669
4476	Windows has numerous arbitrary (and low) limits on things.	4670	Windows has numerous arbitrary (and low) limits on things.
4477		4671
4478	Early versions of winsocket's select only supported waiting for a maximum	4672	Early versions of winsocket's select only supported waiting for a maximum
4479	of C<64> handles (probably owning to the fact that all windows kernels	4673	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4494	runtime libraries. This might get you to about C<512> or C<2048> sockets	4688	runtime libraries. This might get you to about C<512> or C<2048> sockets
4495	(depending on windows version and/or the phase of the moon). To get more,	4689	(depending on windows version and/or the phase of the moon). To get more,
4496	you need to wrap all I/O functions and provide your own fd management, but	4690	you need to wrap all I/O functions and provide your own fd management, but
4497	the cost of calling select (O(n²)) will likely make this unworkable.	4691	the cost of calling select (O(n²)) will likely make this unworkable.
4498		4692
4499	=back
4500
4501	=head2 PORTABILITY REQUIREMENTS	4693	=head2 PORTABILITY REQUIREMENTS
4502		4694
4503	In addition to a working ISO-C implementation and of course the	4695	In addition to a working ISO-C implementation and of course the
4504	backend-specific APIs, libev relies on a few additional extensions:	4696	backend-specific APIs, libev relies on a few additional extensions:
4505		4697
…		…
4543	watchers.	4735	watchers.
4544		4736
4545	=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
4546		4738
4547	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
4548	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
4549	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
4550	implementations implementing IEEE 754, which is basically all existing	4743	implementations using IEEE 754, which is basically all existing ones. With
4551	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4744	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4552	2200.
4553		4745
4554	=back	4746	=back
4555		4747
4556	If you know of other additional requirements drop me a note.	4748	If you know of other additional requirements drop me a note.
4557		4749
…		…
4635	compatibility, so most programs should still compile. Those might be	4827	compatibility, so most programs should still compile. Those might be
4636	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.
4637		4829
4638	=over 4	4830	=over 4
4639		4831
4640	=item C<ev_loop_count> renamed to C<ev_iteration>	4832	=item function/symbol renames
4641		4833
4642	=item C<ev_loop_depth> renamed to C<ev_depth>	4834	A number of functions and symbols have been renamed:
4643		4835
4644	=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
4645		4850
4646	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
4647	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
4648	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>
4649	C<ev_fork> typedef.	4857	typedef.
4650		4858
4651	=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents>	4859	=item C<EV_COMPAT3> backwards compatibility mechanism
4652		4860
4653	This is a simple rename - all other watcher types use their name	4861	The backward compatibility mechanism can be controlled by
4654	as revents flag, and now C<ev_timer> does, too.	4862	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
4655		4863	section.
4656	Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
4657	and continue to be present for the forseeable future, so this is mostly a
4658	documentation change.
4659		4864
4660	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	4865	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4661		4866
4662	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
4663	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	4868	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4670		4875
4671	=over 4	4876	=over 4
4672		4877
4673	=item active	4878	=item active
4674		4879
4675	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.
4676	an event loop) but not yet stopped (disassociated from the event loop).	4881	See L<WATCHER STATES> for details.
4677		4882
4678	=item application	4883	=item application
4679		4884
4680	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.
4681		4890
4682	=item callback	4891	=item callback
4683		4892
4684	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
4685	detected. Callbacks are being passed the event loop, the watcher that	4894	detected. Callbacks are being passed the event loop, the watcher that
4686	received the event, and the actual event bitset.	4895	received the event, and the actual event bitset.
4687		4896
4688	=item callback invocation	4897	=item callback/watcher invocation
4689		4898
4690	The act of calling the callback associated with a watcher.	4899	The act of calling the callback associated with a watcher.
4691		4900
4692	=item event	4901	=item event
4693		4902
…		…
4712	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
4713	watchers and events.	4922	watchers and events.
4714		4923
4715	=item pending	4924	=item pending
4716		4925
4717	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
4718	and stops being pending as soon as the watcher will be invoked or its	4927	detected. See L<WATCHER STATES> for details.
4719	pending status is explicitly cleared by the application.
4720
4721	A watcher can be pending, but not active. Stopping a watcher also clears
4722	its pending status.
4723		4928
4724	=item real time	4929	=item real time
4725		4930
4726	The physical time that is observed. It is apparently strictly monotonic :)	4931	The physical time that is observed. It is apparently strictly monotonic :)
4727		4932
…		…
4734	=item watcher	4939	=item watcher
4735		4940
4736	A data structure that describes interest in certain events. Watchers need	4941	A data structure that describes interest in certain events. Watchers need
4737	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.
4738		4943
4739	=item watcher invocation
4740
4741	The act of calling the callback associated with a watcher.
4742
4743	=back	4944	=back
4744		4945
4745	=head1 AUTHOR	4946	=head1 AUTHOR
4746		4947
4747	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 1.292 by sf-exg, Mon Mar 22 09:57:01 2010 UTC vs. Revision 1.316 by root, Fri Oct 22 09:34:01 2010 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.292 by sf-exg, Mon Mar 22 09:57:01 2010 UTC vs.
Revision 1.316 by root, Fri Oct 22 09:34:01 2010 UTC