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Revision 1.282 by root, Wed Mar 10 08:19:39 2010 UTC vs.
Revision 1.321 by sf-exg, Fri Oct 22 10:50:24 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 practice
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).
…		…
164		165
165	=item ev_tstamp ev_time ()	166	=item ev_tstamp ev_time ()
166		167
167	Returns the current time as libev would use it. Please note that the	168	Returns the current time as libev would use it. Please note that the
168	C<ev_now> function is usually faster and also often returns the timestamp	169	C<ev_now> function is usually faster and also often returns the timestamp
169	you actually want to know.	170	you actually want to know. Also interesting is the combination of
		171	C<ev_update_now> and C<ev_now>.
170		172
171	=item ev_sleep (ev_tstamp interval)	173	=item ev_sleep (ev_tstamp interval)
172		174
173	Sleep for the given interval: The current thread will be blocked until	175	Sleep for the given interval: The current thread will be blocked until
174	either it is interrupted or the given time interval has passed. Basically	176	either it is interrupted or the given time interval has passed. Basically
…		…
191	as this indicates an incompatible change. Minor versions are usually	193	as this indicates an incompatible change. Minor versions are usually
192	compatible to older versions, so a larger minor version alone is usually	194	compatible to older versions, so a larger minor version alone is usually
193	not a problem.	195	not a problem.
194		196
195	Example: Make sure we haven't accidentally been linked against the wrong	197	Example: Make sure we haven't accidentally been linked against the wrong
196	version.	198	version (note, however, that this will not detect other ABI mismatches,
		199	such as LFS or reentrancy).
197		200
198	assert (("libev version mismatch",	201	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	202	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	203	&& ev_version_minor () >= EV_VERSION_MINOR));
201		204
…		…
212	assert (("sorry, no epoll, no sex",	215	assert (("sorry, no epoll, no sex",
213	ev_supported_backends () & EVBACKEND_EPOLL));	216	ev_supported_backends () & EVBACKEND_EPOLL));
214		217
215	=item unsigned int ev_recommended_backends ()	218	=item unsigned int ev_recommended_backends ()
216		219
217	Return the set of all backends compiled into this binary of libev and also	220	Return the set of all backends compiled into this binary of libev and
218	recommended for this platform. This set is often smaller than the one	221	also recommended for this platform, meaning it will work for most file
		222	descriptor types. This set is often smaller than the one returned by
219	returned by C<ev_supported_backends>, as for example kqueue is broken on	223	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
220	most BSDs and will not be auto-detected unless you explicitly request it	224	and will not be auto-detected unless you explicitly request it (assuming
221	(assuming you know what you are doing). This is the set of backends that	225	you know what you are doing). This is the set of backends that libev will
222	libev will probe for if you specify no backends explicitly.	226	probe for if you specify no backends explicitly.
223		227
224	=item unsigned int ev_embeddable_backends ()	228	=item unsigned int ev_embeddable_backends ()
225		229
226	Returns the set of backends that are embeddable in other event loops. This	230	Returns the set of backends that are embeddable in other event loops. This
227	is the theoretical, all-platform, value. To find which backends	231	value is platform-specific but can include backends not available on the
228	might be supported on the current system, you would need to look at	232	current system. To find which embeddable backends might be supported on
229	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	233	the current system, you would need to look at C<ev_embeddable_backends ()
230	recommended ones.	234	& ev_supported_backends ()>, likewise for recommended ones.
231		235
232	See the description of C<ev_embed> watchers for more info.	236	See the description of C<ev_embed> watchers for more info.
233		237
234	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	238	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]
235		239
…		…
291		295
292	=back	296	=back
293		297
294	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	298	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
295		299
296	An event loop is described by a C<struct ev_loop *> (the C<struct>	300	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>	301	I<not> optional in this case unless libev 3 compatibility is disabled, as
298	I<function>).	302	libev 3 had an C<ev_loop> function colliding with the struct name).
299		303
300	The library knows two types of such loops, the I<default> loop, which	304	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	305	supports signals and child events, and dynamically created event loops
302	not.	306	which do not.
303		307
304	=over 4	308	=over 4
305		309
306	=item struct ev_loop *ev_default_loop (unsigned int flags)	310	=item struct ev_loop *ev_default_loop (unsigned int flags)
307		311
…		…
345	useful to try out specific backends to test their performance, or to work	349	useful to try out specific backends to test their performance, or to work
346	around bugs.	350	around bugs.
347		351
348	=item C<EVFLAG_FORKCHECK>	352	=item C<EVFLAG_FORKCHECK>
349		353
350	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	354	Instead of calling C<ev_loop_fork> manually after a fork, you can also
351	a fork, you can also make libev check for a fork in each iteration by	355	make libev check for a fork in each iteration by enabling this flag.
352	enabling this flag.
353		356
354	This works by calling C<getpid ()> on every iteration of the loop,	357	This works by calling C<getpid ()> on every iteration of the loop,
355	and thus this might slow down your event loop if you do a lot of loop	358	and thus this might slow down your event loop if you do a lot of loop
356	iterations and little real work, but is usually not noticeable (on my	359	iterations and little real work, but is usually not noticeable (on my
357	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	360	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
439	of course I<doesn't>, and epoll just loves to report events for totally	442	of course I<doesn't>, and epoll just loves to report events for totally
440	I<different> file descriptors (even already closed ones, so one cannot	443	I<different> file descriptors (even already closed ones, so one cannot
441	even remove them from the set) than registered in the set (especially	444	even remove them from the set) than registered in the set (especially
442	on SMP systems). Libev tries to counter these spurious notifications by	445	on SMP systems). Libev tries to counter these spurious notifications by
443	employing an additional generation counter and comparing that against the	446	employing an additional generation counter and comparing that against the
444	events to filter out spurious ones, recreating the set when required.	447	events to filter out spurious ones, recreating the set when required. Last
		448	not least, it also refuses to work with some file descriptors which work
		449	perfectly fine with C<select> (files, many character devices...).
445		450
446	While stopping, setting and starting an I/O watcher in the same iteration	451	While stopping, setting and starting an I/O watcher in the same iteration
447	will result in some caching, there is still a system call per such	452	will result in some caching, there is still a system call per such
448	incident (because the same I<file descriptor> could point to a different	453	incident (because the same I<file descriptor> could point to a different
449	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	454	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
567	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	572	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
568		573
569	=item struct ev_loop *ev_loop_new (unsigned int flags)	574	=item struct ev_loop *ev_loop_new (unsigned int flags)
570		575
571	Similar to C<ev_default_loop>, but always creates a new event loop that is	576	Similar to C<ev_default_loop>, but always creates a new event loop that is
572	always distinct from the default loop. Unlike the default loop, it cannot	577	always distinct from the default loop.
573	handle signal and child watchers, and attempts to do so will be greeted by
574	undefined behaviour (or a failed assertion if assertions are enabled).
575		578
576	Note that this function I<is> thread-safe, and the recommended way to use	579	Note that this function I<is> thread-safe, and one common way to use
577	libev with threads is indeed to create one loop per thread, and using the	580	libev with threads is indeed to create one loop per thread, and using the
578	default loop in the "main" or "initial" thread.	581	default loop in the "main" or "initial" thread.
579		582
580	Example: Try to create a event loop that uses epoll and nothing else.	583	Example: Try to create a event loop that uses epoll and nothing else.
581		584
…		…
583	if (!epoller)	586	if (!epoller)
584	fatal ("no epoll found here, maybe it hides under your chair");	587	fatal ("no epoll found here, maybe it hides under your chair");
585		588
586	=item ev_default_destroy ()	589	=item ev_default_destroy ()
587		590
588	Destroys the default loop again (frees all memory and kernel state	591	Destroys the default loop (frees all memory and kernel state etc.). None
589	etc.). None of the active event watchers will be stopped in the normal	592	of the active event watchers will be stopped in the normal sense, so
590	sense, so e.g. C<ev_is_active> might still return true. It is your	593	e.g. C<ev_is_active> might still return true. It is your responsibility to
591	responsibility to either stop all watchers cleanly yourself I<before>	594	either stop all watchers cleanly yourself I<before> calling this function,
592	calling this function, or cope with the fact afterwards (which is usually	595	or cope with the fact afterwards (which is usually the easiest thing, you
593	the easiest thing, you can just ignore the watchers and/or C<free ()> them	596	can just ignore the watchers and/or C<free ()> them for example).
594	for example).
595		597
596	Note that certain global state, such as signal state (and installed signal	598	Note that certain global state, such as signal state (and installed signal
597	handlers), will not be freed by this function, and related watchers (such	599	handlers), will not be freed by this function, and related watchers (such
598	as signal and child watchers) would need to be stopped manually.	600	as signal and child watchers) would need to be stopped manually.
599		601
…		…
607	Like C<ev_default_destroy>, but destroys an event loop created by an	609	Like C<ev_default_destroy>, but destroys an event loop created by an
608	earlier call to C<ev_loop_new>.	610	earlier call to C<ev_loop_new>.
609		611
610	=item ev_default_fork ()	612	=item ev_default_fork ()
611		613
612	This function sets a flag that causes subsequent C<ev_loop> iterations	614	This function sets a flag that causes subsequent C<ev_run> iterations
613	to reinitialise the kernel state for backends that have one. Despite the	615	to reinitialise the kernel state for backends that have one. Despite the
614	name, you can call it anytime, but it makes most sense after forking, in	616	name, you can call it anytime, but it makes most sense after forking, in
615	the child process (or both child and parent, but that again makes little	617	the child process (or both child and parent, but that again makes little
616	sense). You I<must> call it in the child before using any of the libev	618	sense). You I<must> call it in the child before using any of the libev
617	functions, and it will only take effect at the next C<ev_loop> iteration.	619	functions, and it will only take effect at the next C<ev_run> iteration.
		620
		621	Again, you I<have> to call it on I<any> loop that you want to re-use after
		622	a fork, I<even if you do not plan to use the loop in the parent>. This is
		623	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		624	during fork.
618		625
619	On the other hand, you only need to call this function in the child	626	On the other hand, you only need to call this function in the child
620	process if and only if you want to use the event library in the child. If	627	process if and only if you want to use the event loop in the child. If
621	you just fork+exec, you don't have to call it at all.	628	you just fork+exec or create a new loop in the child, you don't have to
		629	call it at all (in fact, C<epoll> is so badly broken that it makes a
		630	difference, but libev will usually detect this case on its own and do a
		631	costly reset of the backend).
622		632
623	The function itself is quite fast and it's usually not a problem to call	633	The function itself is quite fast and it's usually not a problem to call
624	it just in case after a fork. To make this easy, the function will fit in	634	it just in case after a fork. To make this easy, the function will fit in
625	quite nicely into a call to C<pthread_atfork>:	635	quite nicely into a call to C<pthread_atfork>:
626		636
…		…
628		638
629	=item ev_loop_fork (loop)	639	=item ev_loop_fork (loop)
630		640
631	Like C<ev_default_fork>, but acts on an event loop created by	641	Like C<ev_default_fork>, but acts on an event loop created by
632	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	642	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
633	after fork that you want to re-use in the child, and how you do this is	643	after fork that you want to re-use in the child, and how you keep track of
634	entirely your own problem.	644	them is entirely your own problem.
635		645
636	=item int ev_is_default_loop (loop)	646	=item int ev_is_default_loop (loop)
637		647
638	Returns true when the given loop is, in fact, the default loop, and false	648	Returns true when the given loop is, in fact, the default loop, and false
639	otherwise.	649	otherwise.
640		650
641	=item unsigned int ev_loop_count (loop)	651	=item unsigned int ev_iteration (loop)
642		652
643	Returns the count of loop iterations for the loop, which is identical to	653	Returns the current iteration count for the event loop, which is identical
644	the number of times libev did poll for new events. It starts at C<0> and	654	to the number of times libev did poll for new events. It starts at C<0>
645	happily wraps around with enough iterations.	655	and happily wraps around with enough iterations.
646		656
647	This value can sometimes be useful as a generation counter of sorts (it	657	This value can sometimes be useful as a generation counter of sorts (it
648	"ticks" the number of loop iterations), as it roughly corresponds with	658	"ticks" the number of loop iterations), as it roughly corresponds with
649	C<ev_prepare> and C<ev_check> calls.	659	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		660	prepare and check phases.
650		661
651	=item unsigned int ev_loop_depth (loop)	662	=item unsigned int ev_depth (loop)
652		663
653	Returns the number of times C<ev_loop> was entered minus the number of	664	Returns the number of times C<ev_run> was entered minus the number of
654	times C<ev_loop> was exited, in other words, the recursion depth.	665	times C<ev_run> was exited, in other words, the recursion depth.
655		666
656	Outside C<ev_loop>, this number is zero. In a callback, this number is	667	Outside C<ev_run>, this number is zero. In a callback, this number is
657	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	668	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
658	in which case it is higher.	669	in which case it is higher.
659		670
660	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	671	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
661	etc.), doesn't count as exit.	672	etc.), doesn't count as "exit" - consider this as a hint to avoid such
		673	ungentleman-like behaviour unless it's really convenient.
662		674
663	=item unsigned int ev_backend (loop)	675	=item unsigned int ev_backend (loop)
664		676
665	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	677	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
666	use.	678	use.
…		…
675		687
676	=item ev_now_update (loop)	688	=item ev_now_update (loop)
677		689
678	Establishes the current time by querying the kernel, updating the time	690	Establishes the current time by querying the kernel, updating the time
679	returned by C<ev_now ()> in the progress. This is a costly operation and	691	returned by C<ev_now ()> in the progress. This is a costly operation and
680	is usually done automatically within C<ev_loop ()>.	692	is usually done automatically within C<ev_run ()>.
681		693
682	This function is rarely useful, but when some event callback runs for a	694	This function is rarely useful, but when some event callback runs for a
683	very long time without entering the event loop, updating libev's idea of	695	very long time without entering the event loop, updating libev's idea of
684	the current time is a good idea.	696	the current time is a good idea.
685		697
…		…
687		699
688	=item ev_suspend (loop)	700	=item ev_suspend (loop)
689		701
690	=item ev_resume (loop)	702	=item ev_resume (loop)
691		703
692	These two functions suspend and resume a loop, for use when the loop is	704	These two functions suspend and resume an event loop, for use when the
693	not used for a while and timeouts should not be processed.	705	loop is not used for a while and timeouts should not be processed.
694		706
695	A typical use case would be an interactive program such as a game: When	707	A typical use case would be an interactive program such as a game: When
696	the user presses C<^Z> to suspend the game and resumes it an hour later it	708	the user presses C<^Z> to suspend the game and resumes it an hour later it
697	would be best to handle timeouts as if no time had actually passed while	709	would be best to handle timeouts as if no time had actually passed while
698	the program was suspended. This can be achieved by calling C<ev_suspend>	710	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
700	C<ev_resume> directly afterwards to resume timer processing.	712	C<ev_resume> directly afterwards to resume timer processing.
701		713
702	Effectively, all C<ev_timer> watchers will be delayed by the time spend	714	Effectively, all C<ev_timer> watchers will be delayed by the time spend
703	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	715	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
704	will be rescheduled (that is, they will lose any events that would have	716	will be rescheduled (that is, they will lose any events that would have
705	occured while suspended).	717	occurred while suspended).
706		718
707	After calling C<ev_suspend> you B<must not> call I<any> function on the	719	After calling C<ev_suspend> you B<must not> call I<any> function on the
708	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	720	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
709	without a previous call to C<ev_suspend>.	721	without a previous call to C<ev_suspend>.
710		722
711	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	723	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
712	event loop time (see C<ev_now_update>).	724	event loop time (see C<ev_now_update>).
713		725
714	=item ev_loop (loop, int flags)	726	=item ev_run (loop, int flags)
715		727
716	Finally, this is it, the event handler. This function usually is called	728	Finally, this is it, the event handler. This function usually is called
717	after you have initialised all your watchers and you want to start	729	after you have initialised all your watchers and you want to start
718	handling events.	730	handling events. It will ask the operating system for any new events, call
		731	the watcher callbacks, an then repeat the whole process indefinitely: This
		732	is why event loops are called I<loops>.
719		733
720	If the flags argument is specified as C<0>, it will not return until	734	If the flags argument is specified as C<0>, it will keep handling events
721	either no event watchers are active anymore or C<ev_unloop> was called.	735	until either no event watchers are active anymore or C<ev_break> was
		736	called.
722		737
723	Please note that an explicit C<ev_unloop> is usually better than	738	Please note that an explicit C<ev_break> is usually better than
724	relying on all watchers to be stopped when deciding when a program has	739	relying on all watchers to be stopped when deciding when a program has
725	finished (especially in interactive programs), but having a program	740	finished (especially in interactive programs), but having a program
726	that automatically loops as long as it has to and no longer by virtue	741	that automatically loops as long as it has to and no longer by virtue
727	of relying on its watchers stopping correctly, that is truly a thing of	742	of relying on its watchers stopping correctly, that is truly a thing of
728	beauty.	743	beauty.
729		744
730	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	745	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
731	those events and any already outstanding ones, but will not block your	746	those events and any already outstanding ones, but will not wait and
732	process in case there are no events and will return after one iteration of	747	block your process in case there are no events and will return after one
733	the loop.	748	iteration of the loop. This is sometimes useful to poll and handle new
		749	events while doing lengthy calculations, to keep the program responsive.
734		750
735	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	751	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
736	necessary) and will handle those and any already outstanding ones. It	752	necessary) and will handle those and any already outstanding ones. It
737	will block your process until at least one new event arrives (which could	753	will block your process until at least one new event arrives (which could
738	be an event internal to libev itself, so there is no guarantee that a	754	be an event internal to libev itself, so there is no guarantee that a
739	user-registered callback will be called), and will return after one	755	user-registered callback will be called), and will return after one
740	iteration of the loop.	756	iteration of the loop.
741		757
742	This is useful if you are waiting for some external event in conjunction	758	This is useful if you are waiting for some external event in conjunction
743	with something not expressible using other libev watchers (i.e. "roll your	759	with something not expressible using other libev watchers (i.e. "roll your
744	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	760	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
745	usually a better approach for this kind of thing.	761	usually a better approach for this kind of thing.
746		762
747	Here are the gory details of what C<ev_loop> does:	763	Here are the gory details of what C<ev_run> does:
748		764
		765	- Increment loop depth.
		766	- Reset the ev_break status.
749	- Before the first iteration, call any pending watchers.	767	- Before the first iteration, call any pending watchers.
		768	LOOP:
750	* If EVFLAG_FORKCHECK was used, check for a fork.	769	- If EVFLAG_FORKCHECK was used, check for a fork.
751	- If a fork was detected (by any means), queue and call all fork watchers.	770	- If a fork was detected (by any means), queue and call all fork watchers.
752	- Queue and call all prepare watchers.	771	- Queue and call all prepare watchers.
		772	- If ev_break was called, goto FINISH.
753	- If we have been forked, detach and recreate the kernel state	773	- If we have been forked, detach and recreate the kernel state
754	as to not disturb the other process.	774	as to not disturb the other process.
755	- Update the kernel state with all outstanding changes.	775	- Update the kernel state with all outstanding changes.
756	- Update the "event loop time" (ev_now ()).	776	- Update the "event loop time" (ev_now ()).
757	- Calculate for how long to sleep or block, if at all	777	- Calculate for how long to sleep or block, if at all
758	(active idle watchers, EVLOOP_NONBLOCK or not having	778	(active idle watchers, EVRUN_NOWAIT or not having
759	any active watchers at all will result in not sleeping).	779	any active watchers at all will result in not sleeping).
760	- Sleep if the I/O and timer collect interval say so.	780	- Sleep if the I/O and timer collect interval say so.
		781	- Increment loop iteration counter.
761	- Block the process, waiting for any events.	782	- Block the process, waiting for any events.
762	- Queue all outstanding I/O (fd) events.	783	- Queue all outstanding I/O (fd) events.
763	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	784	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
764	- Queue all expired timers.	785	- Queue all expired timers.
765	- Queue all expired periodics.	786	- Queue all expired periodics.
766	- Unless any events are pending now, queue all idle watchers.	787	- Queue all idle watchers with priority higher than that of pending events.
767	- Queue all check watchers.	788	- Queue all check watchers.
768	- Call all queued watchers in reverse order (i.e. check watchers first).	789	- Call all queued watchers in reverse order (i.e. check watchers first).
769	Signals and child watchers are implemented as I/O watchers, and will	790	Signals and child watchers are implemented as I/O watchers, and will
770	be handled here by queueing them when their watcher gets executed.	791	be handled here by queueing them when their watcher gets executed.
771	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	792	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
772	were used, or there are no active watchers, return, otherwise	793	were used, or there are no active watchers, goto FINISH, otherwise
773	continue with step *.	794	continue with step LOOP.
		795	FINISH:
		796	- Reset the ev_break status iff it was EVBREAK_ONE.
		797	- Decrement the loop depth.
		798	- Return.
774		799
775	Example: Queue some jobs and then loop until no events are outstanding	800	Example: Queue some jobs and then loop until no events are outstanding
776	anymore.	801	anymore.
777		802
778	... queue jobs here, make sure they register event watchers as long	803	... queue jobs here, make sure they register event watchers as long
779	... as they still have work to do (even an idle watcher will do..)	804	... as they still have work to do (even an idle watcher will do..)
780	ev_loop (my_loop, 0);	805	ev_run (my_loop, 0);
781	... jobs done or somebody called unloop. yeah!	806	... jobs done or somebody called unloop. yeah!
782		807
783	=item ev_unloop (loop, how)	808	=item ev_break (loop, how)
784		809
785	Can be used to make a call to C<ev_loop> return early (but only after it	810	Can be used to make a call to C<ev_run> return early (but only after it
786	has processed all outstanding events). The C<how> argument must be either	811	has processed all outstanding events). The C<how> argument must be either
787	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	812	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
788	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	813	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
789		814
790	This "unloop state" will be cleared when entering C<ev_loop> again.	815	This "unloop state" will be cleared when entering C<ev_run> again.
791		816
792	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	817	It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO##
793		818
794	=item ev_ref (loop)	819	=item ev_ref (loop)
795		820
796	=item ev_unref (loop)	821	=item ev_unref (loop)
797		822
798	Ref/unref can be used to add or remove a reference count on the event	823	Ref/unref can be used to add or remove a reference count on the event
799	loop: Every watcher keeps one reference, and as long as the reference	824	loop: Every watcher keeps one reference, and as long as the reference
800	count is nonzero, C<ev_loop> will not return on its own.	825	count is nonzero, C<ev_run> will not return on its own.
801		826
802	This is useful when you have a watcher that you never intend to	827	This is useful when you have a watcher that you never intend to
803	unregister, but that nevertheless should not keep C<ev_loop> from	828	unregister, but that nevertheless should not keep C<ev_run> from
804	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	829	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
805	before stopping it.	830	before stopping it.
806		831
807	As an example, libev itself uses this for its internal signal pipe: It	832	As an example, libev itself uses this for its internal signal pipe: It
808	is not visible to the libev user and should not keep C<ev_loop> from	833	is not visible to the libev user and should not keep C<ev_run> from
809	exiting if no event watchers registered by it are active. It is also an	834	exiting if no event watchers registered by it are active. It is also an
810	excellent way to do this for generic recurring timers or from within	835	excellent way to do this for generic recurring timers or from within
811	third-party libraries. Just remember to I<unref after start> and I<ref	836	third-party libraries. Just remember to I<unref after start> and I<ref
812	before stop> (but only if the watcher wasn't active before, or was active	837	before stop> (but only if the watcher wasn't active before, or was active
813	before, respectively. Note also that libev might stop watchers itself	838	before, respectively. Note also that libev might stop watchers itself
814	(e.g. non-repeating timers) in which case you have to C<ev_ref>	839	(e.g. non-repeating timers) in which case you have to C<ev_ref>
815	in the callback).	840	in the callback).
816		841
817	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	842	Example: Create a signal watcher, but keep it from keeping C<ev_run>
818	running when nothing else is active.	843	running when nothing else is active.
819		844
820	ev_signal exitsig;	845	ev_signal exitsig;
821	ev_signal_init (&exitsig, sig_cb, SIGINT);	846	ev_signal_init (&exitsig, sig_cb, SIGINT);
822	ev_signal_start (loop, &exitsig);	847	ev_signal_start (loop, &exitsig);
…		…
867	usually doesn't make much sense to set it to a lower value than C<0.01>,	892	usually doesn't make much sense to set it to a lower value than C<0.01>,
868	as this approaches the timing granularity of most systems. Note that if	893	as this approaches the timing granularity of most systems. Note that if
869	you do transactions with the outside world and you can't increase the	894	you do transactions with the outside world and you can't increase the
870	parallelity, then this setting will limit your transaction rate (if you	895	parallelity, then this setting will limit your transaction rate (if you
871	need to poll once per transaction and the I/O collect interval is 0.01,	896	need to poll once per transaction and the I/O collect interval is 0.01,
872	then you can't do more than 100 transations per second).	897	then you can't do more than 100 transactions per second).
873		898
874	Setting the I<timeout collect interval> can improve the opportunity for	899	Setting the I<timeout collect interval> can improve the opportunity for
875	saving power, as the program will "bundle" timer callback invocations that	900	saving power, as the program will "bundle" timer callback invocations that
876	are "near" in time together, by delaying some, thus reducing the number of	901	are "near" in time together, by delaying some, thus reducing the number of
877	times the process sleeps and wakes up again. Another useful technique to	902	times the process sleeps and wakes up again. Another useful technique to
…		…
885	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	910	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
886		911
887	=item ev_invoke_pending (loop)	912	=item ev_invoke_pending (loop)
888		913
889	This call will simply invoke all pending watchers while resetting their	914	This call will simply invoke all pending watchers while resetting their
890	pending state. Normally, C<ev_loop> does this automatically when required,	915	pending state. Normally, C<ev_run> does this automatically when required,
891	but when overriding the invoke callback this call comes handy.	916	but when overriding the invoke callback this call comes handy. This
		917	function can be invoked from a watcher - this can be useful for example
		918	when you want to do some lengthy calculation and want to pass further
		919	event handling to another thread (you still have to make sure only one
		920	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
892		921
893	=item int ev_pending_count (loop)	922	=item int ev_pending_count (loop)
894		923
895	Returns the number of pending watchers - zero indicates that no watchers	924	Returns the number of pending watchers - zero indicates that no watchers
896	are pending.	925	are pending.
897		926
898	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	927	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
899		928
900	This overrides the invoke pending functionality of the loop: Instead of	929	This overrides the invoke pending functionality of the loop: Instead of
901	invoking all pending watchers when there are any, C<ev_loop> will call	930	invoking all pending watchers when there are any, C<ev_run> will call
902	this callback instead. This is useful, for example, when you want to	931	this callback instead. This is useful, for example, when you want to
903	invoke the actual watchers inside another context (another thread etc.).	932	invoke the actual watchers inside another context (another thread etc.).
904		933
905	If you want to reset the callback, use C<ev_invoke_pending> as new	934	If you want to reset the callback, use C<ev_invoke_pending> as new
906	callback.	935	callback.
…		…
909		938
910	Sometimes you want to share the same loop between multiple threads. This	939	Sometimes you want to share the same loop between multiple threads. This
911	can be done relatively simply by putting mutex_lock/unlock calls around	940	can be done relatively simply by putting mutex_lock/unlock calls around
912	each call to a libev function.	941	each call to a libev function.
913		942
914	However, C<ev_loop> can run an indefinite time, so it is not feasible to	943	However, C<ev_run> can run an indefinite time, so it is not feasible
915	wait for it to return. One way around this is to wake up the loop via	944	to wait for it to return. One way around this is to wake up the event
916	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	945	loop via C<ev_break> and C<av_async_send>, another way is to set these
917	and I<acquire> callbacks on the loop.	946	I<release> and I<acquire> callbacks on the loop.
918		947
919	When set, then C<release> will be called just before the thread is	948	When set, then C<release> will be called just before the thread is
920	suspended waiting for new events, and C<acquire> is called just	949	suspended waiting for new events, and C<acquire> is called just
921	afterwards.	950	afterwards.
922		951
…		…
925		954
926	While event loop modifications are allowed between invocations of	955	While event loop modifications are allowed between invocations of
927	C<release> and C<acquire> (that's their only purpose after all), no	956	C<release> and C<acquire> (that's their only purpose after all), no
928	modifications done will affect the event loop, i.e. adding watchers will	957	modifications done will affect the event loop, i.e. adding watchers will
929	have no effect on the set of file descriptors being watched, or the time	958	have no effect on the set of file descriptors being watched, or the time
930	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	959	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
931	to take note of any changes you made.	960	to take note of any changes you made.
932		961
933	In theory, threads executing C<ev_loop> will be async-cancel safe between	962	In theory, threads executing C<ev_run> will be async-cancel safe between
934	invocations of C<release> and C<acquire>.	963	invocations of C<release> and C<acquire>.
935		964
936	See also the locking example in the C<THREADS> section later in this	965	See also the locking example in the C<THREADS> section later in this
937	document.	966	document.
938		967
…		…
947	These two functions can be used to associate arbitrary data with a loop,	976	These two functions can be used to associate arbitrary data with a loop,
948	and are intended solely for the C<invoke_pending_cb>, C<release> and	977	and are intended solely for the C<invoke_pending_cb>, C<release> and
949	C<acquire> callbacks described above, but of course can be (ab-)used for	978	C<acquire> callbacks described above, but of course can be (ab-)used for
950	any other purpose as well.	979	any other purpose as well.
951		980
952	=item ev_loop_verify (loop)	981	=item ev_verify (loop)
953		982
954	This function only does something when C<EV_VERIFY> support has been	983	This function only does something when C<EV_VERIFY> support has been
955	compiled in, which is the default for non-minimal builds. It tries to go	984	compiled in, which is the default for non-minimal builds. It tries to go
956	through all internal structures and checks them for validity. If anything	985	through all internal structures and checks them for validity. If anything
957	is found to be inconsistent, it will print an error message to standard	986	is found to be inconsistent, it will print an error message to standard
…		…
968		997
969	In the following description, uppercase C<TYPE> in names stands for the	998	In the following description, uppercase C<TYPE> in names stands for the
970	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	999	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
971	watchers and C<ev_io_start> for I/O watchers.	1000	watchers and C<ev_io_start> for I/O watchers.
972		1001
973	A watcher is a structure that you create and register to record your	1002	A watcher is an opaque structure that you allocate and register to record
974	interest in some event. For instance, if you want to wait for STDIN to	1003	your interest in some event. To make a concrete example, imagine you want
975	become readable, you would create an C<ev_io> watcher for that:	1004	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1005	for that:
976		1006
977	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1007	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
978	{	1008	{
979	ev_io_stop (w);	1009	ev_io_stop (w);
980	ev_unloop (loop, EVUNLOOP_ALL);	1010	ev_break (loop, EVBREAK_ALL);
981	}	1011	}
982		1012
983	struct ev_loop *loop = ev_default_loop (0);	1013	struct ev_loop *loop = ev_default_loop (0);
984		1014
985	ev_io stdin_watcher;	1015	ev_io stdin_watcher;
986		1016
987	ev_init (&stdin_watcher, my_cb);	1017	ev_init (&stdin_watcher, my_cb);
988	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1018	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
989	ev_io_start (loop, &stdin_watcher);	1019	ev_io_start (loop, &stdin_watcher);
990		1020
991	ev_loop (loop, 0);	1021	ev_run (loop, 0);
992		1022
993	As you can see, you are responsible for allocating the memory for your	1023	As you can see, you are responsible for allocating the memory for your
994	watcher structures (and it is I<usually> a bad idea to do this on the	1024	watcher structures (and it is I<usually> a bad idea to do this on the
995	stack).	1025	stack).
996		1026
997	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1027	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
998	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1028	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
999		1029
1000	Each watcher structure must be initialised by a call to C<ev_init	1030	Each watcher structure must be initialised by a call to C<ev_init (watcher
1001	(watcher *, callback)>, which expects a callback to be provided. This	1031	*, callback)>, which expects a callback to be provided. This callback is
1002	callback gets invoked each time the event occurs (or, in the case of I/O	1032	invoked each time the event occurs (or, in the case of I/O watchers, each
1003	watchers, each time the event loop detects that the file descriptor given	1033	time the event loop detects that the file descriptor given is readable
1004	is readable and/or writable).	1034	and/or writable).
1005		1035
1006	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1036	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1007	macro to configure it, with arguments specific to the watcher type. There	1037	macro to configure it, with arguments specific to the watcher type. There
1008	is also a macro to combine initialisation and setting in one call: C<<	1038	is also a macro to combine initialisation and setting in one call: C<<
1009	ev_TYPE_init (watcher *, callback, ...) >>.	1039	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1032	=item C<EV_WRITE>	1062	=item C<EV_WRITE>
1033		1063
1034	The file descriptor in the C<ev_io> watcher has become readable and/or	1064	The file descriptor in the C<ev_io> watcher has become readable and/or
1035	writable.	1065	writable.
1036		1066
1037	=item C<EV_TIMEOUT>	1067	=item C<EV_TIMER>
1038		1068
1039	The C<ev_timer> watcher has timed out.	1069	The C<ev_timer> watcher has timed out.
1040		1070
1041	=item C<EV_PERIODIC>	1071	=item C<EV_PERIODIC>
1042		1072
…		…
1060		1090
1061	=item C<EV_PREPARE>	1091	=item C<EV_PREPARE>
1062		1092
1063	=item C<EV_CHECK>	1093	=item C<EV_CHECK>
1064		1094
1065	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1095	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1066	to gather new events, and all C<ev_check> watchers are invoked just after	1096	to gather new events, and all C<ev_check> watchers are invoked just after
1067	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1097	C<ev_run> has gathered them, but before it invokes any callbacks for any
1068	received events. Callbacks of both watcher types can start and stop as	1098	received events. Callbacks of both watcher types can start and stop as
1069	many watchers as they want, and all of them will be taken into account	1099	many watchers as they want, and all of them will be taken into account
1070	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1100	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1071	C<ev_loop> from blocking).	1101	C<ev_run> from blocking).
1072		1102
1073	=item C<EV_EMBED>	1103	=item C<EV_EMBED>
1074		1104
1075	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1105	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1076		1106
…		…
1104	example it might indicate that a fd is readable or writable, and if your	1134	example it might indicate that a fd is readable or writable, and if your
1105	callbacks is well-written it can just attempt the operation and cope with	1135	callbacks is well-written it can just attempt the operation and cope with
1106	the error from read() or write(). This will not work in multi-threaded	1136	the error from read() or write(). This will not work in multi-threaded
1107	programs, though, as the fd could already be closed and reused for another	1137	programs, though, as the fd could already be closed and reused for another
1108	thing, so beware.	1138	thing, so beware.
		1139
		1140	=back
		1141
		1142	=head2 WATCHER STATES
		1143
		1144	There are various watcher states mentioned throughout this manual -
		1145	active, pending and so on. In this section these states and the rules to
		1146	transition between them will be described in more detail - and while these
		1147	rules might look complicated, they usually do "the right thing".
		1148
		1149	=over 4
		1150
		1151	=item initialiased
		1152
		1153	Before a watcher can be registered with the event looop it has to be
		1154	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1155	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1156
		1157	In this state it is simply some block of memory that is suitable for use
		1158	in an event loop. It can be moved around, freed, reused etc. at will.
		1159
		1160	=item started/running/active
		1161
		1162	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1163	property of the event loop, and is actively waiting for events. While in
		1164	this state it cannot be accessed (except in a few documented ways), moved,
		1165	freed or anything else - the only legal thing is to keep a pointer to it,
		1166	and call libev functions on it that are documented to work on active watchers.
		1167
		1168	=item pending
		1169
		1170	If a watcher is active and libev determines that an event it is interested
		1171	in has occurred (such as a timer expiring), it will become pending. It will
		1172	stay in this pending state until either it is stopped or its callback is
		1173	about to be invoked, so it is not normally pending inside the watcher
		1174	callback.
		1175
		1176	The watcher might or might not be active while it is pending (for example,
		1177	an expired non-repeating timer can be pending but no longer active). If it
		1178	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1179	but it is still property of the event loop at this time, so cannot be
		1180	moved, freed or reused. And if it is active the rules described in the
		1181	previous item still apply.
		1182
		1183	It is also possible to feed an event on a watcher that is not active (e.g.
		1184	via C<ev_feed_event>), in which case it becomes pending without being
		1185	active.
		1186
		1187	=item stopped
		1188
		1189	A watcher can be stopped implicitly by libev (in which case it might still
		1190	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1191	latter will clear any pending state the watcher might be in, regardless
		1192	of whether it was active or not, so stopping a watcher explicitly before
		1193	freeing it is often a good idea.
		1194
		1195	While stopped (and not pending) the watcher is essentially in the
		1196	initialised state, that is it can be reused, moved, modified in any way
		1197	you wish.
1109		1198
1110	=back	1199	=back
1111		1200
1112	=head2 GENERIC WATCHER FUNCTIONS	1201	=head2 GENERIC WATCHER FUNCTIONS
1113		1202
…		…
1375		1464
1376	For example, to emulate how many other event libraries handle priorities,	1465	For example, to emulate how many other event libraries handle priorities,
1377	you can associate an C<ev_idle> watcher to each such watcher, and in	1466	you can associate an C<ev_idle> watcher to each such watcher, and in
1378	the normal watcher callback, you just start the idle watcher. The real	1467	the normal watcher callback, you just start the idle watcher. The real
1379	processing is done in the idle watcher callback. This causes libev to	1468	processing is done in the idle watcher callback. This causes libev to
1380	continously poll and process kernel event data for the watcher, but when	1469	continuously poll and process kernel event data for the watcher, but when
1381	the lock-out case is known to be rare (which in turn is rare :), this is	1470	the lock-out case is known to be rare (which in turn is rare :), this is
1382	workable.	1471	workable.
1383		1472
1384	Usually, however, the lock-out model implemented that way will perform	1473	Usually, however, the lock-out model implemented that way will perform
1385	miserably under the type of load it was designed to handle. In that case,	1474	miserably under the type of load it was designed to handle. In that case,
…		…
1399	{	1488	{
1400	// stop the I/O watcher, we received the event, but	1489	// stop the I/O watcher, we received the event, but
1401	// are not yet ready to handle it.	1490	// are not yet ready to handle it.
1402	ev_io_stop (EV_A_ w);	1491	ev_io_stop (EV_A_ w);
1403		1492
1404	// start the idle watcher to ahndle the actual event.	1493	// start the idle watcher to handle the actual event.
1405	// it will not be executed as long as other watchers	1494	// it will not be executed as long as other watchers
1406	// with the default priority are receiving events.	1495	// with the default priority are receiving events.
1407	ev_idle_start (EV_A_ &idle);	1496	ev_idle_start (EV_A_ &idle);
1408	}	1497	}
1409		1498
…		…
1463		1552
1464	If you cannot use non-blocking mode, then force the use of a	1553	If you cannot use non-blocking mode, then force the use of a
1465	known-to-be-good backend (at the time of this writing, this includes only	1554	known-to-be-good backend (at the time of this writing, this includes only
1466	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1555	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1467	descriptors for which non-blocking operation makes no sense (such as	1556	descriptors for which non-blocking operation makes no sense (such as
1468	files) - libev doesn't guarentee any specific behaviour in that case.	1557	files) - libev doesn't guarantee any specific behaviour in that case.
1469		1558
1470	Another thing you have to watch out for is that it is quite easy to	1559	Another thing you have to watch out for is that it is quite easy to
1471	receive "spurious" readiness notifications, that is your callback might	1560	receive "spurious" readiness notifications, that is your callback might
1472	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1561	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1473	because there is no data. Not only are some backends known to create a	1562	because there is no data. Not only are some backends known to create a
…		…
1538		1627
1539	So when you encounter spurious, unexplained daemon exits, make sure you	1628	So when you encounter spurious, unexplained daemon exits, make sure you
1540	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1629	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1541	somewhere, as that would have given you a big clue).	1630	somewhere, as that would have given you a big clue).
1542		1631
		1632	=head3 The special problem of accept()ing when you can't
		1633
		1634	Many implementations of the POSIX C<accept> function (for example,
		1635	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1636	connection from the pending queue in all error cases.
		1637
		1638	For example, larger servers often run out of file descriptors (because
		1639	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1640	rejecting the connection, leading to libev signalling readiness on
		1641	the next iteration again (the connection still exists after all), and
		1642	typically causing the program to loop at 100% CPU usage.
		1643
		1644	Unfortunately, the set of errors that cause this issue differs between
		1645	operating systems, there is usually little the app can do to remedy the
		1646	situation, and no known thread-safe method of removing the connection to
		1647	cope with overload is known (to me).
		1648
		1649	One of the easiest ways to handle this situation is to just ignore it
		1650	- when the program encounters an overload, it will just loop until the
		1651	situation is over. While this is a form of busy waiting, no OS offers an
		1652	event-based way to handle this situation, so it's the best one can do.
		1653
		1654	A better way to handle the situation is to log any errors other than
		1655	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1656	messages, and continue as usual, which at least gives the user an idea of
		1657	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1658	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1659	usage.
		1660
		1661	If your program is single-threaded, then you could also keep a dummy file
		1662	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1663	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1664	close that fd, and create a new dummy fd. This will gracefully refuse
		1665	clients under typical overload conditions.
		1666
		1667	The last way to handle it is to simply log the error and C<exit>, as
		1668	is often done with C<malloc> failures, but this results in an easy
		1669	opportunity for a DoS attack.
1543		1670
1544	=head3 Watcher-Specific Functions	1671	=head3 Watcher-Specific Functions
1545		1672
1546	=over 4	1673	=over 4
1547		1674
…		…
1579	...	1706	...
1580	struct ev_loop *loop = ev_default_init (0);	1707	struct ev_loop *loop = ev_default_init (0);
1581	ev_io stdin_readable;	1708	ev_io stdin_readable;
1582	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1709	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1583	ev_io_start (loop, &stdin_readable);	1710	ev_io_start (loop, &stdin_readable);
1584	ev_loop (loop, 0);	1711	ev_run (loop, 0);
1585		1712
1586		1713
1587	=head2 C<ev_timer> - relative and optionally repeating timeouts	1714	=head2 C<ev_timer> - relative and optionally repeating timeouts
1588		1715
1589	Timer watchers are simple relative timers that generate an event after a	1716	Timer watchers are simple relative timers that generate an event after a
…		…
1598	The callback is guaranteed to be invoked only I<after> its timeout has	1725	The callback is guaranteed to be invoked only I<after> its timeout has
1599	passed (not I<at>, so on systems with very low-resolution clocks this	1726	passed (not I<at>, so on systems with very low-resolution clocks this
1600	might introduce a small delay). If multiple timers become ready during the	1727	might introduce a small delay). If multiple timers become ready during the
1601	same loop iteration then the ones with earlier time-out values are invoked	1728	same loop iteration then the ones with earlier time-out values are invoked
1602	before ones of the same priority with later time-out values (but this is	1729	before ones of the same priority with later time-out values (but this is
1603	no longer true when a callback calls C<ev_loop> recursively).	1730	no longer true when a callback calls C<ev_run> recursively).
1604		1731
1605	=head3 Be smart about timeouts	1732	=head3 Be smart about timeouts
1606		1733
1607	Many real-world problems involve some kind of timeout, usually for error	1734	Many real-world problems involve some kind of timeout, usually for error
1608	recovery. A typical example is an HTTP request - if the other side hangs,	1735	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1694	ev_tstamp timeout = last_activity + 60.;	1821	ev_tstamp timeout = last_activity + 60.;
1695		1822
1696	// if last_activity + 60. is older than now, we did time out	1823	// if last_activity + 60. is older than now, we did time out
1697	if (timeout < now)	1824	if (timeout < now)
1698	{	1825	{
1699	// timeout occured, take action	1826	// timeout occurred, take action
1700	}	1827	}
1701	else	1828	else
1702	{	1829	{
1703	// callback was invoked, but there was some activity, re-arm	1830	// callback was invoked, but there was some activity, re-arm
1704	// the watcher to fire in last_activity + 60, which is	1831	// the watcher to fire in last_activity + 60, which is
…		…
1726	to the current time (meaning we just have some activity :), then call the	1853	to the current time (meaning we just have some activity :), then call the
1727	callback, which will "do the right thing" and start the timer:	1854	callback, which will "do the right thing" and start the timer:
1728		1855
1729	ev_init (timer, callback);	1856	ev_init (timer, callback);
1730	last_activity = ev_now (loop);	1857	last_activity = ev_now (loop);
1731	callback (loop, timer, EV_TIMEOUT);	1858	callback (loop, timer, EV_TIMER);
1732		1859
1733	And when there is some activity, simply store the current time in	1860	And when there is some activity, simply store the current time in
1734	C<last_activity>, no libev calls at all:	1861	C<last_activity>, no libev calls at all:
1735		1862
1736	last_actiivty = ev_now (loop);	1863	last_activity = ev_now (loop);
1737		1864
1738	This technique is slightly more complex, but in most cases where the	1865	This technique is slightly more complex, but in most cases where the
1739	time-out is unlikely to be triggered, much more efficient.	1866	time-out is unlikely to be triggered, much more efficient.
1740		1867
1741	Changing the timeout is trivial as well (if it isn't hard-coded in the	1868	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1779		1906
1780	=head3 The special problem of time updates	1907	=head3 The special problem of time updates
1781		1908
1782	Establishing the current time is a costly operation (it usually takes at	1909	Establishing the current time is a costly operation (it usually takes at
1783	least two system calls): EV therefore updates its idea of the current	1910	least two system calls): EV therefore updates its idea of the current
1784	time only before and after C<ev_loop> collects new events, which causes a	1911	time only before and after C<ev_run> collects new events, which causes a
1785	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1912	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1786	lots of events in one iteration.	1913	lots of events in one iteration.
1787		1914
1788	The relative timeouts are calculated relative to the C<ev_now ()>	1915	The relative timeouts are calculated relative to the C<ev_now ()>
1789	time. This is usually the right thing as this timestamp refers to the time	1916	time. This is usually the right thing as this timestamp refers to the time
…		…
1906	}	2033	}
1907		2034
1908	ev_timer mytimer;	2035	ev_timer mytimer;
1909	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2036	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1910	ev_timer_again (&mytimer); /* start timer */	2037	ev_timer_again (&mytimer); /* start timer */
1911	ev_loop (loop, 0);	2038	ev_run (loop, 0);
1912		2039
1913	// and in some piece of code that gets executed on any "activity":	2040	// and in some piece of code that gets executed on any "activity":
1914	// reset the timeout to start ticking again at 10 seconds	2041	// reset the timeout to start ticking again at 10 seconds
1915	ev_timer_again (&mytimer);	2042	ev_timer_again (&mytimer);
1916		2043
…		…
1942		2069
1943	As with timers, the callback is guaranteed to be invoked only when the	2070	As with timers, the callback is guaranteed to be invoked only when the
1944	point in time where it is supposed to trigger has passed. If multiple	2071	point in time where it is supposed to trigger has passed. If multiple
1945	timers become ready during the same loop iteration then the ones with	2072	timers become ready during the same loop iteration then the ones with
1946	earlier time-out values are invoked before ones with later time-out values	2073	earlier time-out values are invoked before ones with later time-out values
1947	(but this is no longer true when a callback calls C<ev_loop> recursively).	2074	(but this is no longer true when a callback calls C<ev_run> recursively).
1948		2075
1949	=head3 Watcher-Specific Functions and Data Members	2076	=head3 Watcher-Specific Functions and Data Members
1950		2077
1951	=over 4	2078	=over 4
1952		2079
…		…
2080	Example: Call a callback every hour, or, more precisely, whenever the	2207	Example: Call a callback every hour, or, more precisely, whenever the
2081	system time is divisible by 3600. The callback invocation times have	2208	system time is divisible by 3600. The callback invocation times have
2082	potentially a lot of jitter, but good long-term stability.	2209	potentially a lot of jitter, but good long-term stability.
2083		2210
2084	static void	2211	static void
2085	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2212	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2086	{	2213	{
2087	... its now a full hour (UTC, or TAI or whatever your clock follows)	2214	... its now a full hour (UTC, or TAI or whatever your clock follows)
2088	}	2215	}
2089		2216
2090	ev_periodic hourly_tick;	2217	ev_periodic hourly_tick;
…		…
2190	Example: Try to exit cleanly on SIGINT.	2317	Example: Try to exit cleanly on SIGINT.
2191		2318
2192	static void	2319	static void
2193	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2320	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2194	{	2321	{
2195	ev_unloop (loop, EVUNLOOP_ALL);	2322	ev_break (loop, EVBREAK_ALL);
2196	}	2323	}
2197		2324
2198	ev_signal signal_watcher;	2325	ev_signal signal_watcher;
2199	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2326	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2200	ev_signal_start (loop, &signal_watcher);	2327	ev_signal_start (loop, &signal_watcher);
…		…
2586		2713
2587	Prepare and check watchers are usually (but not always) used in pairs:	2714	Prepare and check watchers are usually (but not always) used in pairs:
2588	prepare watchers get invoked before the process blocks and check watchers	2715	prepare watchers get invoked before the process blocks and check watchers
2589	afterwards.	2716	afterwards.
2590		2717
2591	You I<must not> call C<ev_loop> or similar functions that enter	2718	You I<must not> call C<ev_run> or similar functions that enter
2592	the current event loop from either C<ev_prepare> or C<ev_check>	2719	the current event loop from either C<ev_prepare> or C<ev_check>
2593	watchers. Other loops than the current one are fine, however. The	2720	watchers. Other loops than the current one are fine, however. The
2594	rationale behind this is that you do not need to check for recursion in	2721	rationale behind this is that you do not need to check for recursion in
2595	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2722	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2596	C<ev_check> so if you have one watcher of each kind they will always be	2723	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2764		2891
2765	if (timeout >= 0)	2892	if (timeout >= 0)
2766	// create/start timer	2893	// create/start timer
2767		2894
2768	// poll	2895	// poll
2769	ev_loop (EV_A_ 0);	2896	ev_run (EV_A_ 0);
2770		2897
2771	// stop timer again	2898	// stop timer again
2772	if (timeout >= 0)	2899	if (timeout >= 0)
2773	ev_timer_stop (EV_A_ &to);	2900	ev_timer_stop (EV_A_ &to);
2774		2901
…		…
2852	if you do not want that, you need to temporarily stop the embed watcher).	2979	if you do not want that, you need to temporarily stop the embed watcher).
2853		2980
2854	=item ev_embed_sweep (loop, ev_embed *)	2981	=item ev_embed_sweep (loop, ev_embed *)
2855		2982
2856	Make a single, non-blocking sweep over the embedded loop. This works	2983	Make a single, non-blocking sweep over the embedded loop. This works
2857	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2984	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2858	appropriate way for embedded loops.	2985	appropriate way for embedded loops.
2859		2986
2860	=item struct ev_loop *other [read-only]	2987	=item struct ev_loop *other [read-only]
2861		2988
2862	The embedded event loop.	2989	The embedded event loop.
…		…
2922	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3049	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2923	handlers will be invoked, too, of course.	3050	handlers will be invoked, too, of course.
2924		3051
2925	=head3 The special problem of life after fork - how is it possible?	3052	=head3 The special problem of life after fork - how is it possible?
2926		3053
2927	Most uses of C<fork()> consist of forking, then some simple calls to ste	3054	Most uses of C<fork()> consist of forking, then some simple calls to set
2928	up/change the process environment, followed by a call to C<exec()>. This	3055	up/change the process environment, followed by a call to C<exec()>. This
2929	sequence should be handled by libev without any problems.	3056	sequence should be handled by libev without any problems.
2930		3057
2931	This changes when the application actually wants to do event handling	3058	This changes when the application actually wants to do event handling
2932	in the child, or both parent in child, in effect "continuing" after the	3059	in the child, or both parent in child, in effect "continuing" after the
…		…
2966	believe me.	3093	believe me.
2967		3094
2968	=back	3095	=back
2969		3096
2970		3097
2971	=head2 C<ev_async> - how to wake up another event loop	3098	=head2 C<ev_async> - how to wake up an event loop
2972		3099
2973	In general, you cannot use an C<ev_loop> from multiple threads or other	3100	In general, you cannot use an C<ev_run> from multiple threads or other
2974	asynchronous sources such as signal handlers (as opposed to multiple event	3101	asynchronous sources such as signal handlers (as opposed to multiple event
2975	loops - those are of course safe to use in different threads).	3102	loops - those are of course safe to use in different threads).
2976		3103
2977	Sometimes, however, you need to wake up another event loop you do not	3104	Sometimes, however, you need to wake up an event loop you do not control,
2978	control, for example because it belongs to another thread. This is what	3105	for example because it belongs to another thread. This is what C<ev_async>
2979	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3106	watchers do: as long as the C<ev_async> watcher is active, you can signal
2980	can signal it by calling C<ev_async_send>, which is thread- and signal	3107	it by calling C<ev_async_send>, which is thread- and signal safe.
2981	safe.
2982		3108
2983	This functionality is very similar to C<ev_signal> watchers, as signals,	3109	This functionality is very similar to C<ev_signal> watchers, as signals,
2984	too, are asynchronous in nature, and signals, too, will be compressed	3110	too, are asynchronous in nature, and signals, too, will be compressed
2985	(i.e. the number of callback invocations may be less than the number of	3111	(i.e. the number of callback invocations may be less than the number of
2986	C<ev_async_sent> calls).	3112	C<ev_async_sent> calls).
…		…
3141		3267
3142	If C<timeout> is less than 0, then no timeout watcher will be	3268	If C<timeout> is less than 0, then no timeout watcher will be
3143	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3269	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3144	repeat = 0) will be started. C<0> is a valid timeout.	3270	repeat = 0) will be started. C<0> is a valid timeout.
3145		3271
3146	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3272	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3147	passed an C<revents> set like normal event callbacks (a combination of	3273	passed an C<revents> set like normal event callbacks (a combination of
3148	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3274	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3149	value passed to C<ev_once>. Note that it is possible to receive I<both>	3275	value passed to C<ev_once>. Note that it is possible to receive I<both>
3150	a timeout and an io event at the same time - you probably should give io	3276	a timeout and an io event at the same time - you probably should give io
3151	events precedence.	3277	events precedence.
3152		3278
3153	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3279	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3154		3280
3155	static void stdin_ready (int revents, void *arg)	3281	static void stdin_ready (int revents, void *arg)
3156	{	3282	{
3157	if (revents & EV_READ)	3283	if (revents & EV_READ)
3158	/* stdin might have data for us, joy! */;	3284	/* stdin might have data for us, joy! */;
3159	else if (revents & EV_TIMEOUT)	3285	else if (revents & EV_TIMER)
3160	/* doh, nothing entered */;	3286	/* doh, nothing entered */;
3161	}	3287	}
3162		3288
3163	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3289	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3164		3290
…		…
3298	myclass obj;	3424	myclass obj;
3299	ev::io iow;	3425	ev::io iow;
3300	iow.set <myclass, &myclass::io_cb> (&obj);	3426	iow.set <myclass, &myclass::io_cb> (&obj);
3301		3427
3302	=item w->set (object *)	3428	=item w->set (object *)
3303
3304	This is an B<experimental> feature that might go away in a future version.
3305		3429
3306	This is a variation of a method callback - leaving out the method to call	3430	This is a variation of a method callback - leaving out the method to call
3307	will default the method to C<operator ()>, which makes it possible to use	3431	will default the method to C<operator ()>, which makes it possible to use
3308	functor objects without having to manually specify the C<operator ()> all	3432	functor objects without having to manually specify the C<operator ()> all
3309	the time. Incidentally, you can then also leave out the template argument	3433	the time. Incidentally, you can then also leave out the template argument
…		…
3349	Associates a different C<struct ev_loop> with this watcher. You can only	3473	Associates a different C<struct ev_loop> with this watcher. You can only
3350	do this when the watcher is inactive (and not pending either).	3474	do this when the watcher is inactive (and not pending either).
3351		3475
3352	=item w->set ([arguments])	3476	=item w->set ([arguments])
3353		3477
3354	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3478	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3355	called at least once. Unlike the C counterpart, an active watcher gets	3479	method or a suitable start method must be called at least once. Unlike the
3356	automatically stopped and restarted when reconfiguring it with this	3480	C counterpart, an active watcher gets automatically stopped and restarted
3357	method.	3481	when reconfiguring it with this method.
3358		3482
3359	=item w->start ()	3483	=item w->start ()
3360		3484
3361	Starts the watcher. Note that there is no C<loop> argument, as the	3485	Starts the watcher. Note that there is no C<loop> argument, as the
3362	constructor already stores the event loop.	3486	constructor already stores the event loop.
3363		3487
		3488	=item w->start ([arguments])
		3489
		3490	Instead of calling C<set> and C<start> methods separately, it is often
		3491	convenient to wrap them in one call. Uses the same type of arguments as
		3492	the configure C<set> method of the watcher.
		3493
3364	=item w->stop ()	3494	=item w->stop ()
3365		3495
3366	Stops the watcher if it is active. Again, no C<loop> argument.	3496	Stops the watcher if it is active. Again, no C<loop> argument.
3367		3497
3368	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3498	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3380		3510
3381	=back	3511	=back
3382		3512
3383	=back	3513	=back
3384		3514
3385	Example: Define a class with an IO and idle watcher, start one of them in	3515	Example: Define a class with two I/O and idle watchers, start the I/O
3386	the constructor.	3516	watchers in the constructor.
3387		3517
3388	class myclass	3518	class myclass
3389	{	3519	{
3390	ev::io io ; void io_cb (ev::io &w, int revents);	3520	ev::io io ; void io_cb (ev::io &w, int revents);
		3521	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3391	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3522	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3392		3523
3393	myclass (int fd)	3524	myclass (int fd)
3394	{	3525	{
3395	io .set <myclass, &myclass::io_cb > (this);	3526	io .set <myclass, &myclass::io_cb > (this);
		3527	io2 .set <myclass, &myclass::io2_cb > (this);
3396	idle.set <myclass, &myclass::idle_cb> (this);	3528	idle.set <myclass, &myclass::idle_cb> (this);
3397		3529
3398	io.start (fd, ev::READ);	3530	io.set (fd, ev::WRITE); // configure the watcher
		3531	io.start (); // start it whenever convenient
		3532
		3533	io2.start (fd, ev::READ); // set + start in one call
3399	}	3534	}
3400	};	3535	};
3401		3536
3402		3537
3403	=head1 OTHER LANGUAGE BINDINGS	3538	=head1 OTHER LANGUAGE BINDINGS
…		…
3477	loop argument"). The C<EV_A> form is used when this is the sole argument,	3612	loop argument"). The C<EV_A> form is used when this is the sole argument,
3478	C<EV_A_> is used when other arguments are following. Example:	3613	C<EV_A_> is used when other arguments are following. Example:
3479		3614
3480	ev_unref (EV_A);	3615	ev_unref (EV_A);
3481	ev_timer_add (EV_A_ watcher);	3616	ev_timer_add (EV_A_ watcher);
3482	ev_loop (EV_A_ 0);	3617	ev_run (EV_A_ 0);
3483		3618
3484	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3619	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3485	which is often provided by the following macro.	3620	which is often provided by the following macro.
3486		3621
3487	=item C<EV_P>, C<EV_P_>	3622	=item C<EV_P>, C<EV_P_>
…		…
3527	}	3662	}
3528		3663
3529	ev_check check;	3664	ev_check check;
3530	ev_check_init (&check, check_cb);	3665	ev_check_init (&check, check_cb);
3531	ev_check_start (EV_DEFAULT_ &check);	3666	ev_check_start (EV_DEFAULT_ &check);
3532	ev_loop (EV_DEFAULT_ 0);	3667	ev_run (EV_DEFAULT_ 0);
3533		3668
3534	=head1 EMBEDDING	3669	=head1 EMBEDDING
3535		3670
3536	Libev can (and often is) directly embedded into host	3671	Libev can (and often is) directly embedded into host
3537	applications. Examples of applications that embed it include the Deliantra	3672	applications. Examples of applications that embed it include the Deliantra
…		…
3622	define before including (or compiling) any of its files. The default in	3757	define before including (or compiling) any of its files. The default in
3623	the absence of autoconf is documented for every option.	3758	the absence of autoconf is documented for every option.
3624		3759
3625	Symbols marked with "(h)" do not change the ABI, and can have different	3760	Symbols marked with "(h)" do not change the ABI, and can have different
3626	values when compiling libev vs. including F<ev.h>, so it is permissible	3761	values when compiling libev vs. including F<ev.h>, so it is permissible
3627	to redefine them before including F<ev.h> without breakign compatibility	3762	to redefine them before including F<ev.h> without breaking compatibility
3628	to a compiled library. All other symbols change the ABI, which means all	3763	to a compiled library. All other symbols change the ABI, which means all
3629	users of libev and the libev code itself must be compiled with compatible	3764	users of libev and the libev code itself must be compiled with compatible
3630	settings.	3765	settings.
3631		3766
3632	=over 4	3767	=over 4
		3768
		3769	=item EV_COMPAT3 (h)
		3770
		3771	Backwards compatibility is a major concern for libev. This is why this
		3772	release of libev comes with wrappers for the functions and symbols that
		3773	have been renamed between libev version 3 and 4.
		3774
		3775	You can disable these wrappers (to test compatibility with future
		3776	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3777	sources. This has the additional advantage that you can drop the C<struct>
		3778	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3779	typedef in that case.
		3780
		3781	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3782	and in some even more future version the compatibility code will be
		3783	removed completely.
3633		3784
3634	=item EV_STANDALONE (h)	3785	=item EV_STANDALONE (h)
3635		3786
3636	Must always be C<1> if you do not use autoconf configuration, which	3787	Must always be C<1> if you do not use autoconf configuration, which
3637	keeps libev from including F<config.h>, and it also defines dummy	3788	keeps libev from including F<config.h>, and it also defines dummy
…		…
3838	fine.	3989	fine.
3839		3990
3840	If your embedding application does not need any priorities, defining these	3991	If your embedding application does not need any priorities, defining these
3841	both to C<0> will save some memory and CPU.	3992	both to C<0> will save some memory and CPU.
3842		3993
3843	=item EV_PERIODIC_ENABLE	3994	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		3995	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		3996	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3844		3997
3845	If undefined or defined to be C<1>, then periodic timers are supported. If	3998	If undefined or defined to be C<1> (and the platform supports it), then
3846	defined to be C<0>, then they are not. Disabling them saves a few kB of	3999	the respective watcher type is supported. If defined to be C<0>, then it
3847	code.	4000	is not. Disabling watcher types mainly saves code size.
3848		4001
3849	=item EV_IDLE_ENABLE	4002	=item EV_FEATURES
3850
3851	If undefined or defined to be C<1>, then idle watchers are supported. If
3852	defined to be C<0>, then they are not. Disabling them saves a few kB of
3853	code.
3854
3855	=item EV_EMBED_ENABLE
3856
3857	If undefined or defined to be C<1>, then embed watchers are supported. If
3858	defined to be C<0>, then they are not. Embed watchers rely on most other
3859	watcher types, which therefore must not be disabled.
3860
3861	=item EV_STAT_ENABLE
3862
3863	If undefined or defined to be C<1>, then stat watchers are supported. If
3864	defined to be C<0>, then they are not.
3865
3866	=item EV_FORK_ENABLE
3867
3868	If undefined or defined to be C<1>, then fork watchers are supported. If
3869	defined to be C<0>, then they are not.
3870
3871	=item EV_SIGNAL_ENABLE
3872
3873	If undefined or defined to be C<1>, then signal watchers are supported. If
3874	defined to be C<0>, then they are not.
3875
3876	=item EV_ASYNC_ENABLE
3877
3878	If undefined or defined to be C<1>, then async watchers are supported. If
3879	defined to be C<0>, then they are not.
3880
3881	=item EV_CHILD_ENABLE
3882
3883	If undefined or defined to be C<1> (and C<_WIN32> is not defined), then
3884	child watchers are supported. If defined to be C<0>, then they are not.
3885
3886	=item EV_MINIMAL
3887		4003
3888	If you need to shave off some kilobytes of code at the expense of some	4004	If you need to shave off some kilobytes of code at the expense of some
3889	speed (but with the full API), define this symbol to C<1>. Currently this	4005	speed (but with the full API), you can define this symbol to request
3890	is used to override some inlining decisions, saves roughly 30% code size	4006	certain subsets of functionality. The default is to enable all features
3891	on amd64. It also selects a much smaller 2-heap for timer management over	4007	that can be enabled on the platform.
3892	the default 4-heap.
3893		4008
3894	You can save even more by disabling watcher types you do not need	4009	A typical way to use this symbol is to define it to C<0> (or to a bitset
3895	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	4010	with some broad features you want) and then selectively re-enable
3896	(C<-DNDEBUG>) will usually reduce code size a lot. Disabling inotify,	4011	additional parts you want, for example if you want everything minimal,
3897	eventfd and signalfd will further help, and disabling backends one doesn't	4012	but multiple event loop support, async and child watchers and the poll
3898	need (e.g. poll, epoll, kqueue, ports) will help further.	4013	backend, use this:
3899		4014
3900	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4015	#define EV_FEATURES 0
3901	provide a bare-bones event library. See C<ev.h> for details on what parts
3902	of the API are still available, and do not complain if this subset changes
3903	over time.
3904
3905	This example set of settings reduces the compiled size of libev from 24Kb
3906	to 8Kb on my GNU/Linux amd64 system (and leaves little in - there is also
3907	an effect on the amount of memory used). With an intelligent-enough linker
3908	further unused functions might be left out as well automatically.
3909
3910	// tuning and API changes
3911	#define EV_MINIMAL 2
3912	#define EV_MULTIPLICITY 0	4016	#define EV_MULTIPLICITY 1
3913	#define EV_MINPRI 0
3914	#define EV_MAXPRI 0
3915
3916	// OS-specific backends
3917	#define EV_USE_INOTIFY 0
3918	#define EV_USE_EVENTFD 0
3919	#define EV_USE_SIGNALFD 0
3920	#define EV_USE_REALTIME 0
3921	#define EV_USE_MONOTONIC 0
3922	#define EV_USE_CLOCK_SYSCALL 0
3923
3924	// disable all backends except select
3925	#define EV_USE_POLL 0	4017	#define EV_USE_POLL 1
3926	#define EV_USE_PORT 0
3927	#define EV_USE_KQUEUE 0
3928	#define EV_USE_EPOLL 0
3929
3930	// disable all watcher types that cna be disabled
3931	#define EV_STAT_ENABLE 0
3932	#define EV_PERIODIC_ENABLE 0
3933	#define EV_IDLE_ENABLE 0
3934	#define EV_FORK_ENABLE 0
3935	#define EV_SIGNAL_ENABLE 0
3936	#define EV_CHILD_ENABLE 0	4018	#define EV_CHILD_ENABLE 1
3937	#define EV_ASYNC_ENABLE 0	4019	#define EV_ASYNC_ENABLE 1
3938	#define EV_EMBED_ENABLE 0	4020
		4021	The actual value is a bitset, it can be a combination of the following
		4022	values:
		4023
		4024	=over 4
		4025
		4026	=item C<1> - faster/larger code
		4027
		4028	Use larger code to speed up some operations.
		4029
		4030	Currently this is used to override some inlining decisions (enlarging the
		4031	code size by roughly 30% on amd64).
		4032
		4033	When optimising for size, use of compiler flags such as C<-Os> with
		4034	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4035	assertions.
		4036
		4037	=item C<2> - faster/larger data structures
		4038
		4039	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4040	hash table sizes and so on. This will usually further increase code size
		4041	and can additionally have an effect on the size of data structures at
		4042	runtime.
		4043
		4044	=item C<4> - full API configuration
		4045
		4046	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4047	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4048
		4049	=item C<8> - full API
		4050
		4051	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4052	details on which parts of the API are still available without this
		4053	feature, and do not complain if this subset changes over time.
		4054
		4055	=item C<16> - enable all optional watcher types
		4056
		4057	Enables all optional watcher types. If you want to selectively enable
		4058	only some watcher types other than I/O and timers (e.g. prepare,
		4059	embed, async, child...) you can enable them manually by defining
		4060	C<EV_watchertype_ENABLE> to C<1> instead.
		4061
		4062	=item C<32> - enable all backends
		4063
		4064	This enables all backends - without this feature, you need to enable at
		4065	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4066
		4067	=item C<64> - enable OS-specific "helper" APIs
		4068
		4069	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4070	default.
		4071
		4072	=back
		4073
		4074	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4075	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4076	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4077	watchers, timers and monotonic clock support.
		4078
		4079	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4080	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4081	your program might be left out as well - a binary starting a timer and an
		4082	I/O watcher then might come out at only 5Kb.
3939		4083
3940	=item EV_AVOID_STDIO	4084	=item EV_AVOID_STDIO
3941		4085
3942	If this is set to C<1> at compiletime, then libev will avoid using stdio	4086	If this is set to C<1> at compiletime, then libev will avoid using stdio
3943	functions (printf, scanf, perror etc.). This will increase the codesize	4087	functions (printf, scanf, perror etc.). This will increase the code size
3944	somewhat, but if your program doesn't otherwise depend on stdio and your	4088	somewhat, but if your program doesn't otherwise depend on stdio and your
3945	libc allows it, this avoids linking in the stdio library which is quite	4089	libc allows it, this avoids linking in the stdio library which is quite
3946	big.	4090	big.
3947		4091
3948	Note that error messages might become less precise when this option is	4092	Note that error messages might become less precise when this option is
…		…
3952		4096
3953	The highest supported signal number, +1 (or, the number of	4097	The highest supported signal number, +1 (or, the number of
3954	signals): Normally, libev tries to deduce the maximum number of signals	4098	signals): Normally, libev tries to deduce the maximum number of signals
3955	automatically, but sometimes this fails, in which case it can be	4099	automatically, but sometimes this fails, in which case it can be
3956	specified. Also, using a lower number than detected (C<32> should be	4100	specified. Also, using a lower number than detected (C<32> should be
3957	good for about any system in existance) can save some memory, as libev	4101	good for about any system in existence) can save some memory, as libev
3958	statically allocates some 12-24 bytes per signal number.	4102	statically allocates some 12-24 bytes per signal number.
3959		4103
3960	=item EV_PID_HASHSIZE	4104	=item EV_PID_HASHSIZE
3961		4105
3962	C<ev_child> watchers use a small hash table to distribute workload by	4106	C<ev_child> watchers use a small hash table to distribute workload by
3963	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4107	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3964	than enough. If you need to manage thousands of children you might want to	4108	usually more than enough. If you need to manage thousands of children you
3965	increase this value (I<must> be a power of two).	4109	might want to increase this value (I<must> be a power of two).
3966		4110
3967	=item EV_INOTIFY_HASHSIZE	4111	=item EV_INOTIFY_HASHSIZE
3968		4112
3969	C<ev_stat> watchers use a small hash table to distribute workload by	4113	C<ev_stat> watchers use a small hash table to distribute workload by
3970	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4114	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3971	usually more than enough. If you need to manage thousands of C<ev_stat>	4115	disabled), usually more than enough. If you need to manage thousands of
3972	watchers you might want to increase this value (I<must> be a power of	4116	C<ev_stat> watchers you might want to increase this value (I<must> be a
3973	two).	4117	power of two).
3974		4118
3975	=item EV_USE_4HEAP	4119	=item EV_USE_4HEAP
3976		4120
3977	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4121	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3978	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4122	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3979	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4123	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3980	faster performance with many (thousands) of watchers.	4124	faster performance with many (thousands) of watchers.
3981		4125
3982	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4126	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3983	(disabled).	4127	will be C<0>.
3984		4128
3985	=item EV_HEAP_CACHE_AT	4129	=item EV_HEAP_CACHE_AT
3986		4130
3987	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4131	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3988	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4132	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3989	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4133	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3990	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4134	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3991	but avoids random read accesses on heap changes. This improves performance	4135	but avoids random read accesses on heap changes. This improves performance
3992	noticeably with many (hundreds) of watchers.	4136	noticeably with many (hundreds) of watchers.
3993		4137
3994	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4138	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3995	(disabled).	4139	will be C<0>.
3996		4140
3997	=item EV_VERIFY	4141	=item EV_VERIFY
3998		4142
3999	Controls how much internal verification (see C<ev_loop_verify ()>) will	4143	Controls how much internal verification (see C<ev_verify ()>) will
4000	be done: If set to C<0>, no internal verification code will be compiled	4144	be done: If set to C<0>, no internal verification code will be compiled
4001	in. If set to C<1>, then verification code will be compiled in, but not	4145	in. If set to C<1>, then verification code will be compiled in, but not
4002	called. If set to C<2>, then the internal verification code will be	4146	called. If set to C<2>, then the internal verification code will be
4003	called once per loop, which can slow down libev. If set to C<3>, then the	4147	called once per loop, which can slow down libev. If set to C<3>, then the
4004	verification code will be called very frequently, which will slow down	4148	verification code will be called very frequently, which will slow down
4005	libev considerably.	4149	libev considerably.
4006		4150
4007	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4151	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4008	C<0>.	4152	will be C<0>.
4009		4153
4010	=item EV_COMMON	4154	=item EV_COMMON
4011		4155
4012	By default, all watchers have a C<void *data> member. By redefining	4156	By default, all watchers have a C<void *data> member. By redefining
4013	this macro to a something else you can include more and other types of	4157	this macro to something else you can include more and other types of
4014	members. You have to define it each time you include one of the files,	4158	members. You have to define it each time you include one of the files,
4015	though, and it must be identical each time.	4159	though, and it must be identical each time.
4016		4160
4017	For example, the perl EV module uses something like this:	4161	For example, the perl EV module uses something like this:
4018		4162
…		…
4071	file.	4215	file.
4072		4216
4073	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4217	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
4074	that everybody includes and which overrides some configure choices:	4218	that everybody includes and which overrides some configure choices:
4075		4219
4076	#define EV_MINIMAL 1	4220	#define EV_FEATURES 8
4077	#define EV_USE_POLL 0	4221	#define EV_USE_SELECT 1
4078	#define EV_MULTIPLICITY 0
4079	#define EV_PERIODIC_ENABLE 0	4222	#define EV_PREPARE_ENABLE 1
		4223	#define EV_IDLE_ENABLE 1
4080	#define EV_STAT_ENABLE 0	4224	#define EV_SIGNAL_ENABLE 1
4081	#define EV_FORK_ENABLE 0	4225	#define EV_CHILD_ENABLE 1
		4226	#define EV_USE_STDEXCEPT 0
4082	#define EV_CONFIG_H <config.h>	4227	#define EV_CONFIG_H <config.h>
4083	#define EV_MINPRI 0
4084	#define EV_MAXPRI 0
4085		4228
4086	#include "ev++.h"	4229	#include "ev++.h"
4087		4230
4088	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4231	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
4089		4232
…		…
4220	userdata *u = ev_userdata (EV_A);	4363	userdata *u = ev_userdata (EV_A);
4221	pthread_mutex_lock (&u->lock);	4364	pthread_mutex_lock (&u->lock);
4222	}	4365	}
4223		4366
4224	The event loop thread first acquires the mutex, and then jumps straight	4367	The event loop thread first acquires the mutex, and then jumps straight
4225	into C<ev_loop>:	4368	into C<ev_run>:
4226		4369
4227	void *	4370	void *
4228	l_run (void *thr_arg)	4371	l_run (void *thr_arg)
4229	{	4372	{
4230	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4373	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4231		4374
4232	l_acquire (EV_A);	4375	l_acquire (EV_A);
4233	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4376	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4234	ev_loop (EV_A_ 0);	4377	ev_run (EV_A_ 0);
4235	l_release (EV_A);	4378	l_release (EV_A);
4236		4379
4237	return 0;	4380	return 0;
4238	}	4381	}
4239		4382
…		…
4291		4434
4292	=head3 COROUTINES	4435	=head3 COROUTINES
4293		4436
4294	Libev is very accommodating to coroutines ("cooperative threads"):	4437	Libev is very accommodating to coroutines ("cooperative threads"):
4295	libev fully supports nesting calls to its functions from different	4438	libev fully supports nesting calls to its functions from different
4296	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4439	coroutines (e.g. you can call C<ev_run> on the same loop from two
4297	different coroutines, and switch freely between both coroutines running	4440	different coroutines, and switch freely between both coroutines running
4298	the loop, as long as you don't confuse yourself). The only exception is	4441	the loop, as long as you don't confuse yourself). The only exception is
4299	that you must not do this from C<ev_periodic> reschedule callbacks.	4442	that you must not do this from C<ev_periodic> reschedule callbacks.
4300		4443
4301	Care has been taken to ensure that libev does not keep local state inside	4444	Care has been taken to ensure that libev does not keep local state inside
4302	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4445	C<ev_run>, and other calls do not usually allow for coroutine switches as
4303	they do not call any callbacks.	4446	they do not call any callbacks.
4304		4447
4305	=head2 COMPILER WARNINGS	4448	=head2 COMPILER WARNINGS
4306		4449
4307	Depending on your compiler and compiler settings, you might get no or a	4450	Depending on your compiler and compiler settings, you might get no or a
…		…
4318	maintainable.	4461	maintainable.
4319		4462
4320	And of course, some compiler warnings are just plain stupid, or simply	4463	And of course, some compiler warnings are just plain stupid, or simply
4321	wrong (because they don't actually warn about the condition their message	4464	wrong (because they don't actually warn about the condition their message
4322	seems to warn about). For example, certain older gcc versions had some	4465	seems to warn about). For example, certain older gcc versions had some
4323	warnings that resulted an extreme number of false positives. These have	4466	warnings that resulted in an extreme number of false positives. These have
4324	been fixed, but some people still insist on making code warn-free with	4467	been fixed, but some people still insist on making code warn-free with
4325	such buggy versions.	4468	such buggy versions.
4326		4469
4327	While libev is written to generate as few warnings as possible,	4470	While libev is written to generate as few warnings as possible,
4328	"warn-free" code is not a goal, and it is recommended not to build libev	4471	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4364	I suggest using suppression lists.	4507	I suggest using suppression lists.
4365		4508
4366		4509
4367	=head1 PORTABILITY NOTES	4510	=head1 PORTABILITY NOTES
4368		4511
		4512	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4513
		4514	GNU/Linux is the only common platform that supports 64 bit file/large file
		4515	interfaces but I<disables> them by default.
		4516
		4517	That means that libev compiled in the default environment doesn't support
		4518	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4519
		4520	Unfortunately, many programs try to work around this GNU/Linux issue
		4521	by enabling the large file API, which makes them incompatible with the
		4522	standard libev compiled for their system.
		4523
		4524	Likewise, libev cannot enable the large file API itself as this would
		4525	suddenly make it incompatible to the default compile time environment,
		4526	i.e. all programs not using special compile switches.
		4527
		4528	=head2 OS/X AND DARWIN BUGS
		4529
		4530	The whole thing is a bug if you ask me - basically any system interface
		4531	you touch is broken, whether it is locales, poll, kqueue or even the
		4532	OpenGL drivers.
		4533
		4534	=head3 C<kqueue> is buggy
		4535
		4536	The kqueue syscall is broken in all known versions - most versions support
		4537	only sockets, many support pipes.
		4538
		4539	Libev tries to work around this by not using C<kqueue> by default on this
		4540	rotten platform, but of course you can still ask for it when creating a
		4541	loop - embedding a socket-only kqueue loop into a select-based one is
		4542	probably going to work well.
		4543
		4544	=head3 C<poll> is buggy
		4545
		4546	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4547	implementation by something calling C<kqueue> internally around the 10.5.6
		4548	release, so now C<kqueue> I<and> C<poll> are broken.
		4549
		4550	Libev tries to work around this by not using C<poll> by default on
		4551	this rotten platform, but of course you can still ask for it when creating
		4552	a loop.
		4553
		4554	=head3 C<select> is buggy
		4555
		4556	All that's left is C<select>, and of course Apple found a way to fuck this
		4557	one up as well: On OS/X, C<select> actively limits the number of file
		4558	descriptors you can pass in to 1024 - your program suddenly crashes when
		4559	you use more.
		4560
		4561	There is an undocumented "workaround" for this - defining
		4562	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4563	work on OS/X.
		4564
		4565	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4566
		4567	=head3 C<errno> reentrancy
		4568
		4569	The default compile environment on Solaris is unfortunately so
		4570	thread-unsafe that you can't even use components/libraries compiled
		4571	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4572	defined by default. A valid, if stupid, implementation choice.
		4573
		4574	If you want to use libev in threaded environments you have to make sure
		4575	it's compiled with C<_REENTRANT> defined.
		4576
		4577	=head3 Event port backend
		4578
		4579	The scalable event interface for Solaris is called "event
		4580	ports". Unfortunately, this mechanism is very buggy in all major
		4581	releases. If you run into high CPU usage, your program freezes or you get
		4582	a large number of spurious wakeups, make sure you have all the relevant
		4583	and latest kernel patches applied. No, I don't know which ones, but there
		4584	are multiple ones to apply, and afterwards, event ports actually work
		4585	great.
		4586
		4587	If you can't get it to work, you can try running the program by setting
		4588	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4589	C<select> backends.
		4590
		4591	=head2 AIX POLL BUG
		4592
		4593	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4594	this by trying to avoid the poll backend altogether (i.e. it's not even
		4595	compiled in), which normally isn't a big problem as C<select> works fine
		4596	with large bitsets on AIX, and AIX is dead anyway.
		4597
4369	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4598	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4599
		4600	=head3 General issues
4370		4601
4371	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4602	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4372	requires, and its I/O model is fundamentally incompatible with the POSIX	4603	requires, and its I/O model is fundamentally incompatible with the POSIX
4373	model. Libev still offers limited functionality on this platform in	4604	model. Libev still offers limited functionality on this platform in
4374	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4605	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4375	descriptors. This only applies when using Win32 natively, not when using	4606	descriptors. This only applies when using Win32 natively, not when using
4376	e.g. cygwin.	4607	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4608	as every compielr comes with a slightly differently broken/incompatible
		4609	environment.
4377		4610
4378	Lifting these limitations would basically require the full	4611	Lifting these limitations would basically require the full
4379	re-implementation of the I/O system. If you are into these kinds of	4612	re-implementation of the I/O system. If you are into this kind of thing,
4380	things, then note that glib does exactly that for you in a very portable	4613	then note that glib does exactly that for you in a very portable way (note
4381	way (note also that glib is the slowest event library known to man).	4614	also that glib is the slowest event library known to man).
4382		4615
4383	There is no supported compilation method available on windows except	4616	There is no supported compilation method available on windows except
4384	embedding it into other applications.	4617	embedding it into other applications.
4385		4618
4386	Sensible signal handling is officially unsupported by Microsoft - libev	4619	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4414	you do I<not> compile the F<ev.c> or any other embedded source files!):	4647	you do I<not> compile the F<ev.c> or any other embedded source files!):
4415		4648
4416	#include "evwrap.h"	4649	#include "evwrap.h"
4417	#include "ev.c"	4650	#include "ev.c"
4418		4651
4419	=over 4
4420
4421	=item The winsocket select function	4652	=head3 The winsocket C<select> function
4422		4653
4423	The winsocket C<select> function doesn't follow POSIX in that it	4654	The winsocket C<select> function doesn't follow POSIX in that it
4424	requires socket I<handles> and not socket I<file descriptors> (it is	4655	requires socket I<handles> and not socket I<file descriptors> (it is
4425	also extremely buggy). This makes select very inefficient, and also	4656	also extremely buggy). This makes select very inefficient, and also
4426	requires a mapping from file descriptors to socket handles (the Microsoft	4657	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4435	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4666	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4436		4667
4437	Note that winsockets handling of fd sets is O(n), so you can easily get a	4668	Note that winsockets handling of fd sets is O(n), so you can easily get a
4438	complexity in the O(n²) range when using win32.	4669	complexity in the O(n²) range when using win32.
4439		4670
4440	=item Limited number of file descriptors	4671	=head3 Limited number of file descriptors
4441		4672
4442	Windows has numerous arbitrary (and low) limits on things.	4673	Windows has numerous arbitrary (and low) limits on things.
4443		4674
4444	Early versions of winsocket's select only supported waiting for a maximum	4675	Early versions of winsocket's select only supported waiting for a maximum
4445	of C<64> handles (probably owning to the fact that all windows kernels	4676	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4460	runtime libraries. This might get you to about C<512> or C<2048> sockets	4691	runtime libraries. This might get you to about C<512> or C<2048> sockets
4461	(depending on windows version and/or the phase of the moon). To get more,	4692	(depending on windows version and/or the phase of the moon). To get more,
4462	you need to wrap all I/O functions and provide your own fd management, but	4693	you need to wrap all I/O functions and provide your own fd management, but
4463	the cost of calling select (O(n²)) will likely make this unworkable.	4694	the cost of calling select (O(n²)) will likely make this unworkable.
4464		4695
4465	=back
4466
4467	=head2 PORTABILITY REQUIREMENTS	4696	=head2 PORTABILITY REQUIREMENTS
4468		4697
4469	In addition to a working ISO-C implementation and of course the	4698	In addition to a working ISO-C implementation and of course the
4470	backend-specific APIs, libev relies on a few additional extensions:	4699	backend-specific APIs, libev relies on a few additional extensions:
4471		4700
…		…
4509	watchers.	4738	watchers.
4510		4739
4511	=item C<double> must hold a time value in seconds with enough accuracy	4740	=item C<double> must hold a time value in seconds with enough accuracy
4512		4741
4513	The type C<double> is used to represent timestamps. It is required to	4742	The type C<double> is used to represent timestamps. It is required to
4514	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4743	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4515	enough for at least into the year 4000. This requirement is fulfilled by	4744	good enough for at least into the year 4000 with millisecond accuracy
		4745	(the design goal for libev). This requirement is overfulfilled by
4516	implementations implementing IEEE 754, which is basically all existing	4746	implementations using IEEE 754, which is basically all existing ones. With
4517	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4747	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4518	2200.
4519		4748
4520	=back	4749	=back
4521		4750
4522	If you know of other additional requirements drop me a note.	4751	If you know of other additional requirements drop me a note.
4523		4752
…		…
4591	involves iterating over all running async watchers or all signal numbers.	4820	involves iterating over all running async watchers or all signal numbers.
4592		4821
4593	=back	4822	=back
4594		4823
4595		4824
		4825	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4826
		4827	The major version 4 introduced some minor incompatible changes to the API.
		4828
		4829	At the moment, the C<ev.h> header file tries to implement superficial
		4830	compatibility, so most programs should still compile. Those might be
		4831	removed in later versions of libev, so better update early than late.
		4832
		4833	=over 4
		4834
		4835	=item function/symbol renames
		4836
		4837	A number of functions and symbols have been renamed:
		4838
		4839	ev_loop => ev_run
		4840	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4841	EVLOOP_ONESHOT => EVRUN_ONCE
		4842
		4843	ev_unloop => ev_break
		4844	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4845	EVUNLOOP_ONE => EVBREAK_ONE
		4846	EVUNLOOP_ALL => EVBREAK_ALL
		4847
		4848	EV_TIMEOUT => EV_TIMER
		4849
		4850	ev_loop_count => ev_iteration
		4851	ev_loop_depth => ev_depth
		4852	ev_loop_verify => ev_verify
		4853
		4854	Most functions working on C<struct ev_loop> objects don't have an
		4855	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4856	associated constants have been renamed to not collide with the C<struct
		4857	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4858	as all other watcher types. Note that C<ev_loop_fork> is still called
		4859	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		4860	typedef.
		4861
		4862	=item C<EV_COMPAT3> backwards compatibility mechanism
		4863
		4864	The backward compatibility mechanism can be controlled by
		4865	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4866	section.
		4867
		4868	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		4869
		4870	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		4871	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		4872	and work, but the library code will of course be larger.
		4873
		4874	=back
		4875
		4876
4596	=head1 GLOSSARY	4877	=head1 GLOSSARY
4597		4878
4598	=over 4	4879	=over 4
4599		4880
4600	=item active	4881	=item active
4601		4882
4602	A watcher is active as long as it has been started (has been attached to	4883	A watcher is active as long as it has been started and not yet stopped.
4603	an event loop) but not yet stopped (disassociated from the event loop).	4884	See L<WATCHER STATES> for details.
4604		4885
4605	=item application	4886	=item application
4606		4887
4607	In this document, an application is whatever is using libev.	4888	In this document, an application is whatever is using libev.
		4889
		4890	=item backend
		4891
		4892	The part of the code dealing with the operating system interfaces.
4608		4893
4609	=item callback	4894	=item callback
4610		4895
4611	The address of a function that is called when some event has been	4896	The address of a function that is called when some event has been
4612	detected. Callbacks are being passed the event loop, the watcher that	4897	detected. Callbacks are being passed the event loop, the watcher that
4613	received the event, and the actual event bitset.	4898	received the event, and the actual event bitset.
4614		4899
4615	=item callback invocation	4900	=item callback/watcher invocation
4616		4901
4617	The act of calling the callback associated with a watcher.	4902	The act of calling the callback associated with a watcher.
4618		4903
4619	=item event	4904	=item event
4620		4905
4621	A change of state of some external event, such as data now being available	4906	A change of state of some external event, such as data now being available
4622	for reading on a file descriptor, time having passed or simply not having	4907	for reading on a file descriptor, time having passed or simply not having
4623	any other events happening anymore.	4908	any other events happening anymore.
4624		4909
4625	In libev, events are represented as single bits (such as C<EV_READ> or	4910	In libev, events are represented as single bits (such as C<EV_READ> or
4626	C<EV_TIMEOUT>).	4911	C<EV_TIMER>).
4627		4912
4628	=item event library	4913	=item event library
4629		4914
4630	A software package implementing an event model and loop.	4915	A software package implementing an event model and loop.
4631		4916
…		…
4639	The model used to describe how an event loop handles and processes	4924	The model used to describe how an event loop handles and processes
4640	watchers and events.	4925	watchers and events.
4641		4926
4642	=item pending	4927	=item pending
4643		4928
4644	A watcher is pending as soon as the corresponding event has been detected,	4929	A watcher is pending as soon as the corresponding event has been
4645	and stops being pending as soon as the watcher will be invoked or its	4930	detected. See L<WATCHER STATES> for details.
4646	pending status is explicitly cleared by the application.
4647
4648	A watcher can be pending, but not active. Stopping a watcher also clears
4649	its pending status.
4650		4931
4651	=item real time	4932	=item real time
4652		4933
4653	The physical time that is observed. It is apparently strictly monotonic :)	4934	The physical time that is observed. It is apparently strictly monotonic :)
4654		4935
…		…
4661	=item watcher	4942	=item watcher
4662		4943
4663	A data structure that describes interest in certain events. Watchers need	4944	A data structure that describes interest in certain events. Watchers need
4664	to be started (attached to an event loop) before they can receive events.	4945	to be started (attached to an event loop) before they can receive events.
4665		4946
4666	=item watcher invocation
4667
4668	The act of calling the callback associated with a watcher.
4669
4670	=back	4947	=back
4671		4948
4672	=head1 AUTHOR	4949	=head1 AUTHOR
4673		4950
4674	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	4951	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.

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