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Comparing libev/ev.3 (file contents):
Revision 1.11 by root, Sat Nov 24 07:14:26 2007 UTC vs.
Revision 1.44 by root, Sat Dec 8 15:30:26 2007 UTC

…		…
127	.\}	127	.\}
128	.rm #[ #] #H #V #F C	128	.rm #[ #] #H #V #F C
129	.\" ========================================================================	129	.\" ========================================================================
130	.\"	130	.\"
131	.IX Title ""<STANDARD INPUT>" 1"	131	.IX Title ""<STANDARD INPUT>" 1"
132	.TH "<STANDARD INPUT>" 1 "2007-11-24" "perl v5.8.8" "User Contributed Perl Documentation"	132	.TH "<STANDARD INPUT>" 1 "2007-12-08" "perl v5.8.8" "User Contributed Perl Documentation"
133	.SH "NAME"	133	.SH "NAME"
134	libev \- a high performance full\-featured event loop written in C	134	libev \- a high performance full\-featured event loop written in C
135	.SH "SYNOPSIS"	135	.SH "SYNOPSIS"
136	.IX Header "SYNOPSIS"	136	.IX Header "SYNOPSIS"
137	.Vb 1	137	.Vb 1
138	\& #include <ev.h>	138	\& #include <ev.h>
139	.Ve	139	.Ve
		140	.SH "EXAMPLE PROGRAM"
		141	.IX Header "EXAMPLE PROGRAM"
		142	.Vb 1
		143	\& #include <ev.h>
		144	.Ve
		145	.PP
		146	.Vb 2
		147	\& ev_io stdin_watcher;
		148	\& ev_timer timeout_watcher;
		149	.Ve
		150	.PP
		151	.Vb 8
		152	\& /* called when data readable on stdin */
		153	\& static void
		154	\& stdin_cb (EV_P_ struct ev_io *w, int revents)
		155	\& {
		156	\& /* puts ("stdin ready"); */
		157	\& ev_io_stop (EV_A_ w); /* just a syntax example */
		158	\& ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		159	\& }
		160	.Ve
		161	.PP
		162	.Vb 6
		163	\& static void
		164	\& timeout_cb (EV_P_ struct ev_timer *w, int revents)
		165	\& {
		166	\& /* puts ("timeout"); */
		167	\& ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		168	\& }
		169	.Ve
		170	.PP
		171	.Vb 4
		172	\& int
		173	\& main (void)
		174	\& {
		175	\& struct ev_loop *loop = ev_default_loop (0);
		176	.Ve
		177	.PP
		178	.Vb 3
		179	\& /* initialise an io watcher, then start it */
		180	\& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
		181	\& ev_io_start (loop, &stdin_watcher);
		182	.Ve
		183	.PP
		184	.Vb 3
		185	\& /* simple non-repeating 5.5 second timeout */
		186	\& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		187	\& ev_timer_start (loop, &timeout_watcher);
		188	.Ve
		189	.PP
		190	.Vb 2
		191	\& /* loop till timeout or data ready */
		192	\& ev_loop (loop, 0);
		193	.Ve
		194	.PP
		195	.Vb 2
		196	\& return 0;
		197	\& }
		198	.Ve
140	.SH "DESCRIPTION"	199	.SH "DESCRIPTION"
141	.IX Header "DESCRIPTION"	200	.IX Header "DESCRIPTION"
		201	The newest version of this document is also available as a html-formatted
		202	web page you might find easier to navigate when reading it for the first
		203	time: <http://cvs.schmorp.de/libev/ev.html>.
		204	.PP
142	Libev is an event loop: you register interest in certain events (such as a	205	Libev is an event loop: you register interest in certain events (such as a
143	file descriptor being readable or a timeout occuring), and it will manage	206	file descriptor being readable or a timeout occuring), and it will manage
144	these event sources and provide your program with events.	207	these event sources and provide your program with events.
145	.PP	208	.PP
146	To do this, it must take more or less complete control over your process	209	To do this, it must take more or less complete control over your process
…		…
151	watchers\fR, which are relatively small C structures you initialise with the	214	watchers\fR, which are relatively small C structures you initialise with the
152	details of the event, and then hand it over to libev by \fIstarting\fR the	215	details of the event, and then hand it over to libev by \fIstarting\fR the
153	watcher.	216	watcher.
154	.SH "FEATURES"	217	.SH "FEATURES"
155	.IX Header "FEATURES"	218	.IX Header "FEATURES"
156	Libev supports select, poll, the linux-specific epoll and the bsd-specific	219	Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
157	kqueue mechanisms for file descriptor events, relative timers, absolute	220	BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
158	timers with customised rescheduling, signal events, process status change	221	for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
159	events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event	222	(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
160	loop mechanism itself (idle, prepare and check watchers). It also is quite	223	with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals
161	fast (see this benchmark comparing	224	(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event
162	it to libevent for example).	225	watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
		226	\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as
		227	file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
		228	(\f(CW\*(C`ev_fork\*(C'\fR).
		229	.PP
		230	It also is quite fast (see this
		231	benchmark comparing it to libevent
		232	for example).
163	.SH "CONVENTIONS"	233	.SH "CONVENTIONS"
164	.IX Header "CONVENTIONS"	234	.IX Header "CONVENTIONS"
165	Libev is very configurable. In this manual the default configuration	235	Libev is very configurable. In this manual the default configuration will
166	will be described, which supports multiple event loops. For more info	236	be described, which supports multiple event loops. For more info about
167	about various configuration options please have a look at the file	237	various configuration options please have a look at \fB\s-1EMBED\s0\fR section in
168	\&\fI\s-1README\s0.embed\fR in the libev distribution. If libev was configured without	238	this manual. If libev was configured without support for multiple event
169	support for multiple event loops, then all functions taking an initial	239	loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR
170	argument of name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR)	240	(which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument.
171	will not have this argument.
172	.SH "TIME REPRESENTATION"	241	.SH "TIME REPRESENTATION"
173	.IX Header "TIME REPRESENTATION"	242	.IX Header "TIME REPRESENTATION"
174	Libev represents time as a single floating point number, representing the	243	Libev represents time as a single floating point number, representing the
175	(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near	244	(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near
176	the beginning of 1970, details are complicated, don't ask). This type is	245	the beginning of 1970, details are complicated, don't ask). This type is
…		…
201	Usually, it's a good idea to terminate if the major versions mismatch,	270	Usually, it's a good idea to terminate if the major versions mismatch,
202	as this indicates an incompatible change. Minor versions are usually	271	as this indicates an incompatible change. Minor versions are usually
203	compatible to older versions, so a larger minor version alone is usually	272	compatible to older versions, so a larger minor version alone is usually
204	not a problem.	273	not a problem.
205	.Sp	274	.Sp
206	Example: make sure we haven't accidentally been linked against the wrong	275	Example: Make sure we haven't accidentally been linked against the wrong
207	version:	276	version.
208	.Sp	277	.Sp
209	.Vb 3	278	.Vb 3
210	\& assert (("libev version mismatch",	279	\& assert (("libev version mismatch",
211	\& ev_version_major () == EV_VERSION_MAJOR	280	\& ev_version_major () == EV_VERSION_MAJOR
212	\& && ev_version_minor () >= EV_VERSION_MINOR));	281	\& && ev_version_minor () >= EV_VERSION_MINOR));
…		…
242	recommended ones.	311	recommended ones.
243	.Sp	312	.Sp
244	See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.	313	See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
245	.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4	314	.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
246	.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"	315	.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
247	Sets the allocation function to use (the prototype is similar to the	316	Sets the allocation function to use (the prototype is similar \- the
248	realloc C function, the semantics are identical). It is used to allocate	317	semantics is identical \- to the realloc C function). It is used to
249	and free memory (no surprises here). If it returns zero when memory	318	allocate and free memory (no surprises here). If it returns zero when
250	needs to be allocated, the library might abort or take some potentially	319	memory needs to be allocated, the library might abort or take some
251	destructive action. The default is your system realloc function.	320	potentially destructive action. The default is your system realloc
		321	function.
252	.Sp	322	.Sp
253	You could override this function in high-availability programs to, say,	323	You could override this function in high-availability programs to, say,
254	free some memory if it cannot allocate memory, to use a special allocator,	324	free some memory if it cannot allocate memory, to use a special allocator,
255	or even to sleep a while and retry until some memory is available.	325	or even to sleep a while and retry until some memory is available.
256	.Sp	326	.Sp
257	Example: replace the libev allocator with one that waits a bit and then	327	Example: Replace the libev allocator with one that waits a bit and then
258	retries: better than mine).	328	retries).
259	.Sp	329	.Sp
260	.Vb 6	330	.Vb 6
261	\& static void *	331	\& static void *
262	\& persistent_realloc (void *ptr, long size)	332	\& persistent_realloc (void *ptr, size_t size)
263	\& {	333	\& {
264	\& for (;;)	334	\& for (;;)
265	\& {	335	\& {
266	\& void *newptr = realloc (ptr, size);	336	\& void *newptr = realloc (ptr, size);
267	.Ve	337	.Ve
…		…
289	callback is set, then libev will expect it to remedy the sitution, no	359	callback is set, then libev will expect it to remedy the sitution, no
290	matter what, when it returns. That is, libev will generally retry the	360	matter what, when it returns. That is, libev will generally retry the
291	requested operation, or, if the condition doesn't go away, do bad stuff	361	requested operation, or, if the condition doesn't go away, do bad stuff
292	(such as abort).	362	(such as abort).
293	.Sp	363	.Sp
294	Example: do the same thing as libev does internally:	364	Example: This is basically the same thing that libev does internally, too.
295	.Sp	365	.Sp
296	.Vb 6	366	.Vb 6
297	\& static void	367	\& static void
298	\& fatal_error (const char *msg)	368	\& fatal_error (const char *msg)
299	\& {	369	\& {
…		…
345	or setgid) then libev will \fInot\fR look at the environment variable	415	or setgid) then libev will \fInot\fR look at the environment variable
346	\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will	416	\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
347	override the flags completely if it is found in the environment. This is	417	override the flags completely if it is found in the environment. This is
348	useful to try out specific backends to test their performance, or to work	418	useful to try out specific backends to test their performance, or to work
349	around bugs.	419	around bugs.
		420	.ie n .IP """EVFLAG_FORKCHECK""" 4
		421	.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
		422	.IX Item "EVFLAG_FORKCHECK"
		423	Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
		424	a fork, you can also make libev check for a fork in each iteration by
		425	enabling this flag.
		426	.Sp
		427	This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
		428	and thus this might slow down your event loop if you do a lot of loop
		429	iterations and little real work, but is usually not noticeable (on my
		430	Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
		431	without a syscall and thus \fIvery\fR fast, but my Linux system also has
		432	\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
		433	.Sp
		434	The big advantage of this flag is that you can forget about fork (and
		435	forget about forgetting to tell libev about forking) when you use this
		436	flag.
		437	.Sp
		438	This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
		439	environment variable.
350	.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4	440	.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
351	.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4	441	.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
352	.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"	442	.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
353	This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as	443	This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
354	libev tries to roll its own fd_set with no limits on the number of fds,	444	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
448	Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is	538	Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is
449	always distinct from the default loop. Unlike the default loop, it cannot	539	always distinct from the default loop. Unlike the default loop, it cannot
450	handle signal and child watchers, and attempts to do so will be greeted by	540	handle signal and child watchers, and attempts to do so will be greeted by
451	undefined behaviour (or a failed assertion if assertions are enabled).	541	undefined behaviour (or a failed assertion if assertions are enabled).
452	.Sp	542	.Sp
453	Example: try to create a event loop that uses epoll and nothing else.	543	Example: Try to create a event loop that uses epoll and nothing else.
454	.Sp	544	.Sp
455	.Vb 3	545	.Vb 3
456	\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	546	\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
457	\& if (!epoller)	547	\& if (!epoller)
458	\& fatal ("no epoll found here, maybe it hides under your chair");	548	\& fatal ("no epoll found here, maybe it hides under your chair");
459	.Ve	549	.Ve
460	.IP "ev_default_destroy ()" 4	550	.IP "ev_default_destroy ()" 4
461	.IX Item "ev_default_destroy ()"	551	.IX Item "ev_default_destroy ()"
462	Destroys the default loop again (frees all memory and kernel state	552	Destroys the default loop again (frees all memory and kernel state
463	etc.). This stops all registered event watchers (by not touching them in	553	etc.). None of the active event watchers will be stopped in the normal
464	any way whatsoever, although you cannot rely on this :).	554	sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your
		555	responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
		556	calling this function, or cope with the fact afterwards (which is usually
		557	the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them
		558	for example).
465	.IP "ev_loop_destroy (loop)" 4	559	.IP "ev_loop_destroy (loop)" 4
466	.IX Item "ev_loop_destroy (loop)"	560	.IX Item "ev_loop_destroy (loop)"
467	Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an	561	Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an
468	earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.	562	earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
469	.IP "ev_default_fork ()" 4	563	.IP "ev_default_fork ()" 4
…		…
491	.IP "ev_loop_fork (loop)" 4	585	.IP "ev_loop_fork (loop)" 4
492	.IX Item "ev_loop_fork (loop)"	586	.IX Item "ev_loop_fork (loop)"
493	Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by	587	Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
494	\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop	588	\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
495	after fork, and how you do this is entirely your own problem.	589	after fork, and how you do this is entirely your own problem.
		590	.IP "unsigned int ev_loop_count (loop)" 4
		591	.IX Item "unsigned int ev_loop_count (loop)"
		592	Returns the count of loop iterations for the loop, which is identical to
		593	the number of times libev did poll for new events. It starts at \f(CW0\fR and
		594	happily wraps around with enough iterations.
		595	.Sp
		596	This value can sometimes be useful as a generation counter of sorts (it
		597	\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
		598	\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
496	.IP "unsigned int ev_backend (loop)" 4	599	.IP "unsigned int ev_backend (loop)" 4
497	.IX Item "unsigned int ev_backend (loop)"	600	.IX Item "unsigned int ev_backend (loop)"
498	Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in	601	Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
499	use.	602	use.
500	.IP "ev_tstamp ev_now (loop)" 4	603	.IP "ev_tstamp ev_now (loop)" 4
…		…
552	\& be handled here by queueing them when their watcher gets executed.	655	\& be handled here by queueing them when their watcher gets executed.
553	\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	656	\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
554	\& were used, return, otherwise continue with step *.	657	\& were used, return, otherwise continue with step *.
555	.Ve	658	.Ve
556	.Sp	659	.Sp
557	Example: queue some jobs and then loop until no events are outsanding	660	Example: Queue some jobs and then loop until no events are outsanding
558	anymore.	661	anymore.
559	.Sp	662	.Sp
560	.Vb 4	663	.Vb 4
561	\& ... queue jobs here, make sure they register event watchers as long	664	\& ... queue jobs here, make sure they register event watchers as long
562	\& ... as they still have work to do (even an idle watcher will do..)	665	\& ... as they still have work to do (even an idle watcher will do..)
…		…
584	visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if	687	visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if
585	no event watchers registered by it are active. It is also an excellent	688	no event watchers registered by it are active. It is also an excellent
586	way to do this for generic recurring timers or from within third-party	689	way to do this for generic recurring timers or from within third-party
587	libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.	690	libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
588	.Sp	691	.Sp
589	Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR	692	Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
590	running when nothing else is active.	693	running when nothing else is active.
591	.Sp	694	.Sp
592	.Vb 4	695	.Vb 4
593	\& struct dv_signal exitsig;	696	\& struct ev_signal exitsig;
594	\& ev_signal_init (&exitsig, sig_cb, SIGINT);	697	\& ev_signal_init (&exitsig, sig_cb, SIGINT);
595	\& ev_signal_start (myloop, &exitsig);	698	\& ev_signal_start (loop, &exitsig);
596	\& evf_unref (myloop);	699	\& evf_unref (loop);
597	.Ve	700	.Ve
598	.Sp	701	.Sp
599	Example: for some weird reason, unregister the above signal handler again.	702	Example: For some weird reason, unregister the above signal handler again.
600	.Sp	703	.Sp
601	.Vb 2	704	.Vb 2
602	\& ev_ref (myloop);	705	\& ev_ref (loop);
603	\& ev_signal_stop (myloop, &exitsig);	706	\& ev_signal_stop (loop, &exitsig);
604	.Ve	707	.Ve
605	.SH "ANATOMY OF A WATCHER"	708	.SH "ANATOMY OF A WATCHER"
606	.IX Header "ANATOMY OF A WATCHER"	709	.IX Header "ANATOMY OF A WATCHER"
607	A watcher is a structure that you create and register to record your	710	A watcher is a structure that you create and register to record your
608	interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to	711	interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
…		…
680	The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread.	783	The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread.
681	.ie n .IP """EV_CHILD""" 4	784	.ie n .IP """EV_CHILD""" 4
682	.el .IP "\f(CWEV_CHILD\fR" 4	785	.el .IP "\f(CWEV_CHILD\fR" 4
683	.IX Item "EV_CHILD"	786	.IX Item "EV_CHILD"
684	The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change.	787	The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change.
		788	.ie n .IP """EV_STAT""" 4
		789	.el .IP "\f(CWEV_STAT\fR" 4
		790	.IX Item "EV_STAT"
		791	The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow.
685	.ie n .IP """EV_IDLE""" 4	792	.ie n .IP """EV_IDLE""" 4
686	.el .IP "\f(CWEV_IDLE\fR" 4	793	.el .IP "\f(CWEV_IDLE\fR" 4
687	.IX Item "EV_IDLE"	794	.IX Item "EV_IDLE"
688	The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do.	795	The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do.
689	.ie n .IP """EV_PREPARE""" 4	796	.ie n .IP """EV_PREPARE""" 4
…		…
699	\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any	806	\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any
700	received events. Callbacks of both watcher types can start and stop as	807	received events. Callbacks of both watcher types can start and stop as
701	many watchers as they want, and all of them will be taken into account	808	many watchers as they want, and all of them will be taken into account
702	(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep	809	(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep
703	\&\f(CW\*(C`ev_loop\*(C'\fR from blocking).	810	\&\f(CW\*(C`ev_loop\*(C'\fR from blocking).
		811	.ie n .IP """EV_EMBED""" 4
		812	.el .IP "\f(CWEV_EMBED\fR" 4
		813	.IX Item "EV_EMBED"
		814	The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention.
		815	.ie n .IP """EV_FORK""" 4
		816	.el .IP "\f(CWEV_FORK\fR" 4
		817	.IX Item "EV_FORK"
		818	The event loop has been resumed in the child process after fork (see
		819	\&\f(CW\*(C`ev_fork\*(C'\fR).
704	.ie n .IP """EV_ERROR""" 4	820	.ie n .IP """EV_ERROR""" 4
705	.el .IP "\f(CWEV_ERROR\fR" 4	821	.el .IP "\f(CWEV_ERROR\fR" 4
706	.IX Item "EV_ERROR"	822	.IX Item "EV_ERROR"
707	An unspecified error has occured, the watcher has been stopped. This might	823	An unspecified error has occured, the watcher has been stopped. This might
708	happen because the watcher could not be properly started because libev	824	happen because the watcher could not be properly started because libev
…		…
713	Libev will usually signal a few \*(L"dummy\*(R" events together with an error,	829	Libev will usually signal a few \*(L"dummy\*(R" events together with an error,
714	for example it might indicate that a fd is readable or writable, and if	830	for example it might indicate that a fd is readable or writable, and if
715	your callbacks is well-written it can just attempt the operation and cope	831	your callbacks is well-written it can just attempt the operation and cope
716	with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded	832	with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded
717	programs, though, so beware.	833	programs, though, so beware.
718	.Sh "\s-1SUMMARY\s0 \s-1OF\s0 \s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"	834	.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
719	.IX Subsection "SUMMARY OF GENERIC WATCHER FUNCTIONS"	835	.IX Subsection "GENERIC WATCHER FUNCTIONS"
720	In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,	836	In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,
721	e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers.	837	e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers.
722	.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4	838	.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
723	.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4	839	.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
724	.IX Item "ev_init (ev_TYPE *watcher, callback)"	840	.IX Item "ev_init (ev_TYPE *watcher, callback)"
…		…
730	which rolls both calls into one.	846	which rolls both calls into one.
731	.Sp	847	.Sp
732	You can reinitialise a watcher at any time as long as it has been stopped	848	You can reinitialise a watcher at any time as long as it has been stopped
733	(or never started) and there are no pending events outstanding.	849	(or never started) and there are no pending events outstanding.
734	.Sp	850	.Sp
735	The callbakc is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher,	851	The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher,
736	int revents)\*(C'\fR.	852	int revents)\*(C'\fR.
737	.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4	853	.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4
738	.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4	854	.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4
739	.IX Item "ev_TYPE_set (ev_TYPE *, [args])"	855	.IX Item "ev_TYPE_set (ev_TYPE *, [args])"
740	This macro initialises the type-specific parts of a watcher. You need to	856	This macro initialises the type-specific parts of a watcher. You need to
…		…
773	.IP "bool ev_is_pending (ev_TYPE *watcher)" 4	889	.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
774	.IX Item "bool ev_is_pending (ev_TYPE *watcher)"	890	.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
775	Returns a true value iff the watcher is pending, (i.e. it has outstanding	891	Returns a true value iff the watcher is pending, (i.e. it has outstanding
776	events but its callback has not yet been invoked). As long as a watcher	892	events but its callback has not yet been invoked). As long as a watcher
777	is pending (but not active) you must not call an init function on it (but	893	is pending (but not active) you must not call an init function on it (but
778	\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to	894	\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
779	libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).	895	make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
		896	it).
780	.IP "callback = ev_cb (ev_TYPE *watcher)" 4	897	.IP "callback ev_cb (ev_TYPE *watcher)" 4
781	.IX Item "callback = ev_cb (ev_TYPE *watcher)"	898	.IX Item "callback ev_cb (ev_TYPE *watcher)"
782	Returns the callback currently set on the watcher.	899	Returns the callback currently set on the watcher.
783	.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4	900	.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
784	.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"	901	.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
785	Change the callback. You can change the callback at virtually any time	902	Change the callback. You can change the callback at virtually any time
786	(modulo threads).	903	(modulo threads).
		904	.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
		905	.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
		906	.PD 0
		907	.IP "int ev_priority (ev_TYPE *watcher)" 4
		908	.IX Item "int ev_priority (ev_TYPE *watcher)"
		909	.PD
		910	Set and query the priority of the watcher. The priority is a small
		911	integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
		912	(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
		913	before watchers with lower priority, but priority will not keep watchers
		914	from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
		915	.Sp
		916	This means that priorities are \fIonly\fR used for ordering callback
		917	invocation after new events have been received. This is useful, for
		918	example, to reduce latency after idling, or more often, to bind two
		919	watchers on the same event and make sure one is called first.
		920	.Sp
		921	If you need to suppress invocation when higher priority events are pending
		922	you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
		923	.Sp
		924	You \fImust not\fR change the priority of a watcher as long as it is active or
		925	pending.
		926	.Sp
		927	The default priority used by watchers when no priority has been set is
		928	always \f(CW0\fR, which is supposed to not be too high and not be too low :).
		929	.Sp
		930	Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
		931	fine, as long as you do not mind that the priority value you query might
		932	or might not have been adjusted to be within valid range.
		933	.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
		934	.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
		935	Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
		936	\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
		937	can deal with that fact.
		938	.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
		939	.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
		940	If the watcher is pending, this function returns clears its pending status
		941	and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
		942	watcher isn't pending it does nothing and returns \f(CW0\fR.
787	.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"	943	.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
788	.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"	944	.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
789	Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change	945	Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
790	and read at any time, libev will completely ignore it. This can be used	946	and read at any time, libev will completely ignore it. This can be used
791	to associate arbitrary data with your watcher. If you need more data and	947	to associate arbitrary data with your watcher. If you need more data and
…		…
812	\& struct my_io *w = (struct my_io *)w_;	968	\& struct my_io *w = (struct my_io *)w_;
813	\& ...	969	\& ...
814	\& }	970	\& }
815	.Ve	971	.Ve
816	.PP	972	.PP
817	More interesting and less C\-conformant ways of catsing your callback type	973	More interesting and less C\-conformant ways of casting your callback type
818	have been omitted....	974	instead have been omitted.
		975	.PP
		976	Another common scenario is having some data structure with multiple
		977	watchers:
		978	.PP
		979	.Vb 6
		980	\& struct my_biggy
		981	\& {
		982	\& int some_data;
		983	\& ev_timer t1;
		984	\& ev_timer t2;
		985	\& }
		986	.Ve
		987	.PP
		988	In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
		989	you need to use \f(CW\*(C`offsetof\*(C'\fR:
		990	.PP
		991	.Vb 1
		992	\& #include <stddef.h>
		993	.Ve
		994	.PP
		995	.Vb 6
		996	\& static void
		997	\& t1_cb (EV_P_ struct ev_timer *w, int revents)
		998	\& {
		999	\& struct my_biggy big = (struct my_biggy *
		1000	\& (((char *)w) - offsetof (struct my_biggy, t1));
		1001	\& }
		1002	.Ve
		1003	.PP
		1004	.Vb 6
		1005	\& static void
		1006	\& t2_cb (EV_P_ struct ev_timer *w, int revents)
		1007	\& {
		1008	\& struct my_biggy big = (struct my_biggy *
		1009	\& (((char *)w) - offsetof (struct my_biggy, t2));
		1010	\& }
		1011	.Ve
819	.SH "WATCHER TYPES"	1012	.SH "WATCHER TYPES"
820	.IX Header "WATCHER TYPES"	1013	.IX Header "WATCHER TYPES"
821	This section describes each watcher in detail, but will not repeat	1014	This section describes each watcher in detail, but will not repeat
822	information given in the last section.	1015	information given in the last section. Any initialisation/set macros,
		1016	functions and members specific to the watcher type are explained.
		1017	.PP
		1018	Members are additionally marked with either \fI[read\-only]\fR, meaning that,
		1019	while the watcher is active, you can look at the member and expect some
		1020	sensible content, but you must not modify it (you can modify it while the
		1021	watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
		1022	means you can expect it to have some sensible content while the watcher
		1023	is active, but you can also modify it. Modifying it may not do something
		1024	sensible or take immediate effect (or do anything at all), but libev will
		1025	not crash or malfunction in any way.
823	.ie n .Sh """ev_io"" \- is this file descriptor readable or writable"	1026	.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?"
824	.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable"	1027	.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?"
825	.IX Subsection "ev_io - is this file descriptor readable or writable"	1028	.IX Subsection "ev_io - is this file descriptor readable or writable?"
826	I/O watchers check whether a file descriptor is readable or writable	1029	I/O watchers check whether a file descriptor is readable or writable
827	in each iteration of the event loop (This behaviour is called	1030	in each iteration of the event loop, or, more precisely, when reading
828	level-triggering because you keep receiving events as long as the	1031	would not block the process and writing would at least be able to write
829	condition persists. Remember you can stop the watcher if you don't want to	1032	some data. This behaviour is called level-triggering because you keep
830	act on the event and neither want to receive future events).	1033	receiving events as long as the condition persists. Remember you can stop
		1034	the watcher if you don't want to act on the event and neither want to
		1035	receive future events.
831	.PP	1036	.PP
832	In general you can register as many read and/or write event watchers per	1037	In general you can register as many read and/or write event watchers per
833	fd as you want (as long as you don't confuse yourself). Setting all file	1038	fd as you want (as long as you don't confuse yourself). Setting all file
834	descriptors to non-blocking mode is also usually a good idea (but not	1039	descriptors to non-blocking mode is also usually a good idea (but not
835	required if you know what you are doing).	1040	required if you know what you are doing).
836	.PP	1041	.PP
837	You have to be careful with dup'ed file descriptors, though. Some backends	1042	You have to be careful with dup'ed file descriptors, though. Some backends
838	(the linux epoll backend is a notable example) cannot handle dup'ed file	1043	(the linux epoll backend is a notable example) cannot handle dup'ed file
839	descriptors correctly if you register interest in two or more fds pointing	1044	descriptors correctly if you register interest in two or more fds pointing
840	to the same underlying file/socket etc. description (that is, they share	1045	to the same underlying file/socket/etc. description (that is, they share
841	the same underlying \*(L"file open\*(R").	1046	the same underlying \*(L"file open\*(R").
842	.PP	1047	.PP
843	If you must do this, then force the use of a known-to-be-good backend	1048	If you must do this, then force the use of a known-to-be-good backend
844	(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and	1049	(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
845	\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).	1050	\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
		1051	.PP
		1052	Another thing you have to watch out for is that it is quite easy to
		1053	receive \*(L"spurious\*(R" readyness notifications, that is your callback might
		1054	be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block
		1055	because there is no data. Not only are some backends known to create a
		1056	lot of those (for example solaris ports), it is very easy to get into
		1057	this situation even with a relatively standard program structure. Thus
		1058	it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
		1059	\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
		1060	.PP
		1061	If you cannot run the fd in non-blocking mode (for example you should not
		1062	play around with an Xlib connection), then you have to seperately re-test
		1063	whether a file descriptor is really ready with a known-to-be good interface
		1064	such as poll (fortunately in our Xlib example, Xlib already does this on
		1065	its own, so its quite safe to use).
846	.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4	1066	.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
847	.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"	1067	.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
848	.PD 0	1068	.PD 0
849	.IP "ev_io_set (ev_io *, int fd, int events)" 4	1069	.IP "ev_io_set (ev_io *, int fd, int events)" 4
850	.IX Item "ev_io_set (ev_io *, int fd, int events)"	1070	.IX Item "ev_io_set (ev_io *, int fd, int events)"
851	.PD	1071	.PD
852	Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive	1072	Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
853	events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_READ |	1073	rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or
854	EV_WRITE\*(C'\fR to receive the given events.	1074	\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events.
855	.Sp	1075	.IP "int fd [read\-only]" 4
856	Please note that most of the more scalable backend mechanisms (for example	1076	.IX Item "int fd [read-only]"
857	epoll and solaris ports) can result in spurious readyness notifications	1077	The file descriptor being watched.
858	for file descriptors, so you practically need to use non-blocking I/O (and	1078	.IP "int events [read\-only]" 4
859	treat callback invocation as hint only), or retest separately with a safe	1079	.IX Item "int events [read-only]"
860	interface before doing I/O (XLib can do this), or force the use of either	1080	The events being watched.
861	\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR, which don't suffer from this
862	problem. Also note that it is quite easy to have your callback invoked
863	when the readyness condition is no longer valid even when employing
864	typical ways of handling events, so its a good idea to use non-blocking
865	I/O unconditionally.
866	.PP	1081	.PP
867	Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well	1082	Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
868	readable, but only once. Since it is likely line\-buffered, you could	1083	readable, but only once. Since it is likely line\-buffered, you could
869	attempt to read a whole line in the callback:	1084	attempt to read a whole line in the callback.
870	.PP	1085	.PP
871	.Vb 6	1086	.Vb 6
872	\& static void	1087	\& static void
873	\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1088	\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
874	\& {	1089	\& {
…		…
883	\& struct ev_io stdin_readable;	1098	\& struct ev_io stdin_readable;
884	\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1099	\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
885	\& ev_io_start (loop, &stdin_readable);	1100	\& ev_io_start (loop, &stdin_readable);
886	\& ev_loop (loop, 0);	1101	\& ev_loop (loop, 0);
887	.Ve	1102	.Ve
888	.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts"	1103	.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
889	.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts"	1104	.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
890	.IX Subsection "ev_timer - relative and optionally recurring timeouts"	1105	.IX Subsection "ev_timer - relative and optionally repeating timeouts"
891	Timer watchers are simple relative timers that generate an event after a	1106	Timer watchers are simple relative timers that generate an event after a
892	given time, and optionally repeating in regular intervals after that.	1107	given time, and optionally repeating in regular intervals after that.
893	.PP	1108	.PP
894	The timers are based on real time, that is, if you register an event that	1109	The timers are based on real time, that is, if you register an event that
895	times out after an hour and you reset your system clock to last years	1110	times out after an hour and you reset your system clock to last years
…		…
929	.IP "ev_timer_again (loop)" 4	1144	.IP "ev_timer_again (loop)" 4
930	.IX Item "ev_timer_again (loop)"	1145	.IX Item "ev_timer_again (loop)"
931	This will act as if the timer timed out and restart it again if it is	1146	This will act as if the timer timed out and restart it again if it is
932	repeating. The exact semantics are:	1147	repeating. The exact semantics are:
933	.Sp	1148	.Sp
		1149	If the timer is pending, its pending status is cleared.
		1150	.Sp
934	If the timer is started but nonrepeating, stop it.	1151	If the timer is started but nonrepeating, stop it (as if it timed out).
935	.Sp	1152	.Sp
936	If the timer is repeating, either start it if necessary (with the repeat	1153	If the timer is repeating, either start it if necessary (with the
937	value), or reset the running timer to the repeat value.	1154	\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
938	.Sp	1155	.Sp
939	This sounds a bit complicated, but here is a useful and typical	1156	This sounds a bit complicated, but here is a useful and typical
940	example: Imagine you have a tcp connection and you want a so-called idle	1157	example: Imagine you have a tcp connection and you want a so-called idle
941	timeout, that is, you want to be called when there have been, say, 60	1158	timeout, that is, you want to be called when there have been, say, 60
942	seconds of inactivity on the socket. The easiest way to do this is to	1159	seconds of inactivity on the socket. The easiest way to do this is to
943	configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each	1160	configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call
944	time you successfully read or write some data. If you go into an idle	1161	\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
945	state where you do not expect data to travel on the socket, you can stop	1162	you go into an idle state where you do not expect data to travel on the
946	the timer, and again will automatically restart it if need be.	1163	socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
		1164	automatically restart it if need be.
		1165	.Sp
		1166	That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
		1167	altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
		1168	.Sp
		1169	.Vb 8
		1170	\& ev_timer_init (timer, callback, 0., 5.);
		1171	\& ev_timer_again (loop, timer);
		1172	\& ...
		1173	\& timer->again = 17.;
		1174	\& ev_timer_again (loop, timer);
		1175	\& ...
		1176	\& timer->again = 10.;
		1177	\& ev_timer_again (loop, timer);
		1178	.Ve
		1179	.Sp
		1180	This is more slightly efficient then stopping/starting the timer each time
		1181	you want to modify its timeout value.
		1182	.IP "ev_tstamp repeat [read\-write]" 4
		1183	.IX Item "ev_tstamp repeat [read-write]"
		1184	The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
		1185	or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
		1186	which is also when any modifications are taken into account.
947	.PP	1187	.PP
948	Example: create a timer that fires after 60 seconds.	1188	Example: Create a timer that fires after 60 seconds.
949	.PP	1189	.PP
950	.Vb 5	1190	.Vb 5
951	\& static void	1191	\& static void
952	\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1192	\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
953	\& {	1193	\& {
…		…
959	\& struct ev_timer mytimer;	1199	\& struct ev_timer mytimer;
960	\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1200	\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
961	\& ev_timer_start (loop, &mytimer);	1201	\& ev_timer_start (loop, &mytimer);
962	.Ve	1202	.Ve
963	.PP	1203	.PP
964	Example: create a timeout timer that times out after 10 seconds of	1204	Example: Create a timeout timer that times out after 10 seconds of
965	inactivity.	1205	inactivity.
966	.PP	1206	.PP
967	.Vb 5	1207	.Vb 5
968	\& static void	1208	\& static void
969	\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1209	\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
…		…
982	.Vb 3	1222	.Vb 3
983	\& // and in some piece of code that gets executed on any "activity":	1223	\& // and in some piece of code that gets executed on any "activity":
984	\& // reset the timeout to start ticking again at 10 seconds	1224	\& // reset the timeout to start ticking again at 10 seconds
985	\& ev_timer_again (&mytimer);	1225	\& ev_timer_again (&mytimer);
986	.Ve	1226	.Ve
987	.ie n .Sh """ev_periodic"" \- to cron or not to cron"	1227	.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
988	.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron"	1228	.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?"
989	.IX Subsection "ev_periodic - to cron or not to cron"	1229	.IX Subsection "ev_periodic - to cron or not to cron?"
990	Periodic watchers are also timers of a kind, but they are very versatile	1230	Periodic watchers are also timers of a kind, but they are very versatile
991	(and unfortunately a bit complex).	1231	(and unfortunately a bit complex).
992	.PP	1232	.PP
993	Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time)	1233	Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time)
994	but on wallclock time (absolute time). You can tell a periodic watcher	1234	but on wallclock time (absolute time). You can tell a periodic watcher
995	to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a	1235	to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
996	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	1236	periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
997	+ 10.>) and then reset your system clock to the last year, then it will	1237	+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
998	take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger	1238	take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
999	roughly 10 seconds later and of course not if you reset your system time	1239	roughly 10 seconds later and of course not if you reset your system time
1000	again).	1240	again).
1001	.PP	1241	.PP
1002	They can also be used to implement vastly more complex timers, such as	1242	They can also be used to implement vastly more complex timers, such as
…		…
1083	.IX Item "ev_periodic_again (loop, ev_periodic *)"	1323	.IX Item "ev_periodic_again (loop, ev_periodic *)"
1084	Simply stops and restarts the periodic watcher again. This is only useful	1324	Simply stops and restarts the periodic watcher again. This is only useful
1085	when you changed some parameters or the reschedule callback would return	1325	when you changed some parameters or the reschedule callback would return
1086	a different time than the last time it was called (e.g. in a crond like	1326	a different time than the last time it was called (e.g. in a crond like
1087	program when the crontabs have changed).	1327	program when the crontabs have changed).
		1328	.IP "ev_tstamp interval [read\-write]" 4
		1329	.IX Item "ev_tstamp interval [read-write]"
		1330	The current interval value. Can be modified any time, but changes only
		1331	take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
		1332	called.
		1333	.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
		1334	.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
		1335	The current reschedule callback, or \f(CW0\fR, if this functionality is
		1336	switched off. Can be changed any time, but changes only take effect when
		1337	the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1088	.PP	1338	.PP
1089	Example: call a callback every hour, or, more precisely, whenever the	1339	Example: Call a callback every hour, or, more precisely, whenever the
1090	system clock is divisible by 3600. The callback invocation times have	1340	system clock is divisible by 3600. The callback invocation times have
1091	potentially a lot of jittering, but good long-term stability.	1341	potentially a lot of jittering, but good long-term stability.
1092	.PP	1342	.PP
1093	.Vb 5	1343	.Vb 5
1094	\& static void	1344	\& static void
…		…
1102	\& struct ev_periodic hourly_tick;	1352	\& struct ev_periodic hourly_tick;
1103	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1353	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1104	\& ev_periodic_start (loop, &hourly_tick);	1354	\& ev_periodic_start (loop, &hourly_tick);
1105	.Ve	1355	.Ve
1106	.PP	1356	.PP
1107	Example: the same as above, but use a reschedule callback to do it:	1357	Example: The same as above, but use a reschedule callback to do it:
1108	.PP	1358	.PP
1109	.Vb 1	1359	.Vb 1
1110	\& #include <math.h>	1360	\& #include <math.h>
1111	.Ve	1361	.Ve
1112	.PP	1362	.PP
…		…
1120	.PP	1370	.PP
1121	.Vb 1	1371	.Vb 1
1122	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1372	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1123	.Ve	1373	.Ve
1124	.PP	1374	.PP
1125	Example: call a callback every hour, starting now:	1375	Example: Call a callback every hour, starting now:
1126	.PP	1376	.PP
1127	.Vb 4	1377	.Vb 4
1128	\& struct ev_periodic hourly_tick;	1378	\& struct ev_periodic hourly_tick;
1129	\& ev_periodic_init (&hourly_tick, clock_cb,	1379	\& ev_periodic_init (&hourly_tick, clock_cb,
1130	\& fmod (ev_now (loop), 3600.), 3600., 0);	1380	\& fmod (ev_now (loop), 3600.), 3600., 0);
1131	\& ev_periodic_start (loop, &hourly_tick);	1381	\& ev_periodic_start (loop, &hourly_tick);
1132	.Ve	1382	.Ve
1133	.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled"	1383	.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!"
1134	.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled"	1384	.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
1135	.IX Subsection "ev_signal - signal me when a signal gets signalled"	1385	.IX Subsection "ev_signal - signal me when a signal gets signalled!"
1136	Signal watchers will trigger an event when the process receives a specific	1386	Signal watchers will trigger an event when the process receives a specific
1137	signal one or more times. Even though signals are very asynchronous, libev	1387	signal one or more times. Even though signals are very asynchronous, libev
1138	will try it's best to deliver signals synchronously, i.e. as part of the	1388	will try it's best to deliver signals synchronously, i.e. as part of the
1139	normal event processing, like any other event.	1389	normal event processing, like any other event.
1140	.PP	1390	.PP
…		…
1150	.IP "ev_signal_set (ev_signal *, int signum)" 4	1400	.IP "ev_signal_set (ev_signal *, int signum)" 4
1151	.IX Item "ev_signal_set (ev_signal *, int signum)"	1401	.IX Item "ev_signal_set (ev_signal *, int signum)"
1152	.PD	1402	.PD
1153	Configures the watcher to trigger on the given signal number (usually one	1403	Configures the watcher to trigger on the given signal number (usually one
1154	of the \f(CW\*(C`SIGxxx\*(C'\fR constants).	1404	of the \f(CW\*(C`SIGxxx\*(C'\fR constants).
		1405	.IP "int signum [read\-only]" 4
		1406	.IX Item "int signum [read-only]"
		1407	The signal the watcher watches out for.
1155	.ie n .Sh """ev_child"" \- wait for pid status changes"	1408	.ie n .Sh """ev_child"" \- watch out for process status changes"
1156	.el .Sh "\f(CWev_child\fP \- wait for pid status changes"	1409	.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
1157	.IX Subsection "ev_child - wait for pid status changes"	1410	.IX Subsection "ev_child - watch out for process status changes"
1158	Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to	1411	Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
1159	some child status changes (most typically when a child of yours dies).	1412	some child status changes (most typically when a child of yours dies).
1160	.IP "ev_child_init (ev_child *, callback, int pid)" 4	1413	.IP "ev_child_init (ev_child *, callback, int pid)" 4
1161	.IX Item "ev_child_init (ev_child *, callback, int pid)"	1414	.IX Item "ev_child_init (ev_child *, callback, int pid)"
1162	.PD 0	1415	.PD 0
…		…
1167	\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look	1420	\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look
1168	at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see	1421	at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see
1169	the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems	1422	the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems
1170	\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the	1423	\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the
1171	process causing the status change.	1424	process causing the status change.
		1425	.IP "int pid [read\-only]" 4
		1426	.IX Item "int pid [read-only]"
		1427	The process id this watcher watches out for, or \f(CW0\fR, meaning any process id.
		1428	.IP "int rpid [read\-write]" 4
		1429	.IX Item "int rpid [read-write]"
		1430	The process id that detected a status change.
		1431	.IP "int rstatus [read\-write]" 4
		1432	.IX Item "int rstatus [read-write]"
		1433	The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
		1434	\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1172	.PP	1435	.PP
1173	Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.	1436	Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1174	.PP	1437	.PP
1175	.Vb 5	1438	.Vb 5
1176	\& static void	1439	\& static void
1177	\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1440	\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1178	\& {	1441	\& {
…		…
1183	.Vb 3	1446	.Vb 3
1184	\& struct ev_signal signal_watcher;	1447	\& struct ev_signal signal_watcher;
1185	\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1448	\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1186	\& ev_signal_start (loop, &sigint_cb);	1449	\& ev_signal_start (loop, &sigint_cb);
1187	.Ve	1450	.Ve
		1451	.ie n .Sh """ev_stat"" \- did the file attributes just change?"
		1452	.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?"
		1453	.IX Subsection "ev_stat - did the file attributes just change?"
		1454	This watches a filesystem path for attribute changes. That is, it calls
		1455	\&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed
		1456	compared to the last time, invoking the callback if it did.
		1457	.PP
		1458	The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
		1459	not exist\*(R" is a status change like any other. The condition \*(L"path does
		1460	not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
		1461	otherwise always forced to be at least one) and all the other fields of
		1462	the stat buffer having unspecified contents.
		1463	.PP
		1464	The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
		1465	relative and your working directory changes, the behaviour is undefined.
		1466	.PP
		1467	Since there is no standard to do this, the portable implementation simply
		1468	calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
		1469	can specify a recommended polling interval for this case. If you specify
		1470	a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
		1471	unspecified default\fR value will be used (which you can expect to be around
		1472	five seconds, although this might change dynamically). Libev will also
		1473	impose a minimum interval which is currently around \f(CW0.1\fR, but thats
		1474	usually overkill.
		1475	.PP
		1476	This watcher type is not meant for massive numbers of stat watchers,
		1477	as even with OS-supported change notifications, this can be
		1478	resource\-intensive.
		1479	.PP
		1480	At the time of this writing, only the Linux inotify interface is
		1481	implemented (implementing kqueue support is left as an exercise for the
		1482	reader). Inotify will be used to give hints only and should not change the
		1483	semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
		1484	to fall back to regular polling again even with inotify, but changes are
		1485	usually detected immediately, and if the file exists there will be no
		1486	polling.
		1487	.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
		1488	.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
		1489	.PD 0
		1490	.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
		1491	.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
		1492	.PD
		1493	Configures the watcher to wait for status changes of the given
		1494	\&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to
		1495	be detected and should normally be specified as \f(CW0\fR to let libev choose
		1496	a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same
		1497	path for as long as the watcher is active.
		1498	.Sp
		1499	The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected,
		1500	relative to the attributes at the time the watcher was started (or the
		1501	last change was detected).
		1502	.IP "ev_stat_stat (ev_stat *)" 4
		1503	.IX Item "ev_stat_stat (ev_stat *)"
		1504	Updates the stat buffer immediately with new values. If you change the
		1505	watched path in your callback, you could call this fucntion to avoid
		1506	detecting this change (while introducing a race condition). Can also be
		1507	useful simply to find out the new values.
		1508	.IP "ev_statdata attr [read\-only]" 4
		1509	.IX Item "ev_statdata attr [read-only]"
		1510	The most-recently detected attributes of the file. Although the type is of
		1511	\&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types
		1512	suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there
		1513	was some error while \f(CW\*(C`stat\*(C'\fRing the file.
		1514	.IP "ev_statdata prev [read\-only]" 4
		1515	.IX Item "ev_statdata prev [read-only]"
		1516	The previous attributes of the file. The callback gets invoked whenever
		1517	\&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR.
		1518	.IP "ev_tstamp interval [read\-only]" 4
		1519	.IX Item "ev_tstamp interval [read-only]"
		1520	The specified interval.
		1521	.IP "const char *path [read\-only]" 4
		1522	.IX Item "const char *path [read-only]"
		1523	The filesystem path that is being watched.
		1524	.PP
		1525	Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
		1526	.PP
		1527	.Vb 15
		1528	\& static void
		1529	\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
		1530	\& {
		1531	\& /* /etc/passwd changed in some way */
		1532	\& if (w->attr.st_nlink)
		1533	\& {
		1534	\& printf ("passwd current size %ld\en", (long)w->attr.st_size);
		1535	\& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime);
		1536	\& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime);
		1537	\& }
		1538	\& else
		1539	\& /* you shalt not abuse printf for puts */
		1540	\& puts ("wow, /etc/passwd is not there, expect problems. "
		1541	\& "if this is windows, they already arrived\en");
		1542	\& }
		1543	.Ve
		1544	.PP
		1545	.Vb 2
		1546	\& ...
		1547	\& ev_stat passwd;
		1548	.Ve
		1549	.PP
		1550	.Vb 2
		1551	\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1552	\& ev_stat_start (loop, &passwd);
		1553	.Ve
1188	.ie n .Sh """ev_idle"" \- when you've got nothing better to do"	1554	.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1189	.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do"	1555	.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1190	.IX Subsection "ev_idle - when you've got nothing better to do"	1556	.IX Subsection "ev_idle - when you've got nothing better to do..."
1191	Idle watchers trigger events when there are no other events are pending	1557	Idle watchers trigger events when no other events of the same or higher
1192	(prepare, check and other idle watchers do not count). That is, as long	1558	priority are pending (prepare, check and other idle watchers do not
1193	as your process is busy handling sockets or timeouts (or even signals,	1559	count).
1194	imagine) it will not be triggered. But when your process is idle all idle	1560	.PP
1195	watchers are being called again and again, once per event loop iteration \-	1561	That is, as long as your process is busy handling sockets or timeouts
		1562	(or even signals, imagine) of the same or higher priority it will not be
		1563	triggered. But when your process is idle (or only lower-priority watchers
		1564	are pending), the idle watchers are being called once per event loop
1196	until stopped, that is, or your process receives more events and becomes	1565	iteration \- until stopped, that is, or your process receives more events
1197	busy.	1566	and becomes busy again with higher priority stuff.
1198	.PP	1567	.PP
1199	The most noteworthy effect is that as long as any idle watchers are	1568	The most noteworthy effect is that as long as any idle watchers are
1200	active, the process will not block when waiting for new events.	1569	active, the process will not block when waiting for new events.
1201	.PP	1570	.PP
1202	Apart from keeping your process non-blocking (which is a useful	1571	Apart from keeping your process non-blocking (which is a useful
…		…
1207	.IX Item "ev_idle_init (ev_signal *, callback)"	1576	.IX Item "ev_idle_init (ev_signal *, callback)"
1208	Initialises and configures the idle watcher \- it has no parameters of any	1577	Initialises and configures the idle watcher \- it has no parameters of any
1209	kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,	1578	kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1210	believe me.	1579	believe me.
1211	.PP	1580	.PP
1212	Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the	1581	Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
1213	callback, free it. Alos, use no error checking, as usual.	1582	callback, free it. Also, use no error checking, as usual.
1214	.PP	1583	.PP
1215	.Vb 7	1584	.Vb 7
1216	\& static void	1585	\& static void
1217	\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1586	\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1218	\& {	1587	\& {
…		…
1225	.Vb 3	1594	.Vb 3
1226	\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1595	\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1227	\& ev_idle_init (idle_watcher, idle_cb);	1596	\& ev_idle_init (idle_watcher, idle_cb);
1228	\& ev_idle_start (loop, idle_cb);	1597	\& ev_idle_start (loop, idle_cb);
1229	.Ve	1598	.Ve
1230	.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop"	1599	.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!"
1231	.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop"	1600	.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
1232	.IX Subsection "ev_prepare and ev_check - customise your event loop"	1601	.IX Subsection "ev_prepare and ev_check - customise your event loop!"
1233	Prepare and check watchers are usually (but not always) used in tandem:	1602	Prepare and check watchers are usually (but not always) used in tandem:
1234	prepare watchers get invoked before the process blocks and check watchers	1603	prepare watchers get invoked before the process blocks and check watchers
1235	afterwards.	1604	afterwards.
1236	.PP	1605	.PP
		1606	You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter
		1607	the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR
		1608	watchers. Other loops than the current one are fine, however. The
		1609	rationale behind this is that you do not need to check for recursion in
		1610	those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking,
		1611	\&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be
		1612	called in pairs bracketing the blocking call.
		1613	.PP
1237	Their main purpose is to integrate other event mechanisms into libev and	1614	Their main purpose is to integrate other event mechanisms into libev and
1238	their use is somewhat advanced. This could be used, for example, to track	1615	their use is somewhat advanced. This could be used, for example, to track
1239	variable changes, implement your own watchers, integrate net-snmp or a	1616	variable changes, implement your own watchers, integrate net-snmp or a
1240	coroutine library and lots more.	1617	coroutine library and lots more. They are also occasionally useful if
		1618	you cache some data and want to flush it before blocking (for example,
		1619	in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR
		1620	watcher).
1241	.PP	1621	.PP
1242	This is done by examining in each prepare call which file descriptors need	1622	This is done by examining in each prepare call which file descriptors need
1243	to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for	1623	to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for
1244	them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries	1624	them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries
1245	provide just this functionality). Then, in the check watcher you check for	1625	provide just this functionality). Then, in the check watcher you check for
…		…
1264	.PD	1644	.PD
1265	Initialises and configures the prepare or check watcher \- they have no	1645	Initialises and configures the prepare or check watcher \- they have no
1266	parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR	1646	parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1267	macros, but using them is utterly, utterly and completely pointless.	1647	macros, but using them is utterly, utterly and completely pointless.
1268	.PP	1648	.PP
1269	Example: *TODO*.	1649	There are a number of principal ways to embed other event loops or modules
		1650	into libev. Here are some ideas on how to include libadns into libev
		1651	(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
		1652	use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
		1653	embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
		1654	into the Glib event loop).
		1655	.PP
		1656	Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
		1657	and in a check watcher, destroy them and call into libadns. What follows
		1658	is pseudo-code only of course. This requires you to either use a low
		1659	priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
		1660	the callbacks for the IO/timeout watchers might not have been called yet.
		1661	.PP
		1662	.Vb 2
		1663	\& static ev_io iow [nfd];
		1664	\& static ev_timer tw;
		1665	.Ve
		1666	.PP
		1667	.Vb 4
		1668	\& static void
		1669	\& io_cb (ev_loop *loop, ev_io *w, int revents)
		1670	\& {
		1671	\& }
		1672	.Ve
		1673	.PP
		1674	.Vb 8
		1675	\& // create io watchers for each fd and a timer before blocking
		1676	\& static void
		1677	\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
		1678	\& {
		1679	\& int timeout = 3600000;
		1680	\& struct pollfd fds [nfd];
		1681	\& // actual code will need to loop here and realloc etc.
		1682	\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1683	.Ve
		1684	.PP
		1685	.Vb 3
		1686	\& /* the callback is illegal, but won't be called as we stop during check */
		1687	\& ev_timer_init (&tw, 0, timeout * 1e-3);
		1688	\& ev_timer_start (loop, &tw);
		1689	.Ve
		1690	.PP
		1691	.Vb 6
		1692	\& // create one ev_io per pollfd
		1693	\& for (int i = 0; i < nfd; ++i)
		1694	\& {
		1695	\& ev_io_init (iow + i, io_cb, fds [i].fd,
		1696	\& ((fds [i].events & POLLIN ? EV_READ : 0)
		1697	\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1698	.Ve
		1699	.PP
		1700	.Vb 4
		1701	\& fds [i].revents = 0;
		1702	\& ev_io_start (loop, iow + i);
		1703	\& }
		1704	\& }
		1705	.Ve
		1706	.PP
		1707	.Vb 5
		1708	\& // stop all watchers after blocking
		1709	\& static void
		1710	\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
		1711	\& {
		1712	\& ev_timer_stop (loop, &tw);
		1713	.Ve
		1714	.PP
		1715	.Vb 8
		1716	\& for (int i = 0; i < nfd; ++i)
		1717	\& {
		1718	\& // set the relevant poll flags
		1719	\& // could also call adns_processreadable etc. here
		1720	\& struct pollfd *fd = fds + i;
		1721	\& int revents = ev_clear_pending (iow + i);
		1722	\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1723	\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1724	.Ve
		1725	.PP
		1726	.Vb 3
		1727	\& // now stop the watcher
		1728	\& ev_io_stop (loop, iow + i);
		1729	\& }
		1730	.Ve
		1731	.PP
		1732	.Vb 2
		1733	\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1734	\& }
		1735	.Ve
		1736	.PP
		1737	Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
		1738	in the prepare watcher and would dispose of the check watcher.
		1739	.PP
		1740	Method 3: If the module to be embedded supports explicit event
		1741	notification (adns does), you can also make use of the actual watcher
		1742	callbacks, and only destroy/create the watchers in the prepare watcher.
		1743	.PP
		1744	.Vb 5
		1745	\& static void
		1746	\& timer_cb (EV_P_ ev_timer *w, int revents)
		1747	\& {
		1748	\& adns_state ads = (adns_state)w->data;
		1749	\& update_now (EV_A);
		1750	.Ve
		1751	.PP
		1752	.Vb 2
		1753	\& adns_processtimeouts (ads, &tv_now);
		1754	\& }
		1755	.Ve
		1756	.PP
		1757	.Vb 5
		1758	\& static void
		1759	\& io_cb (EV_P_ ev_io *w, int revents)
		1760	\& {
		1761	\& adns_state ads = (adns_state)w->data;
		1762	\& update_now (EV_A);
		1763	.Ve
		1764	.PP
		1765	.Vb 3
		1766	\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1767	\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1768	\& }
		1769	.Ve
		1770	.PP
		1771	.Vb 1
		1772	\& // do not ever call adns_afterpoll
		1773	.Ve
		1774	.PP
		1775	Method 4: Do not use a prepare or check watcher because the module you
		1776	want to embed is too inflexible to support it. Instead, youc na override
		1777	their poll function. The drawback with this solution is that the main
		1778	loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
		1779	this.
		1780	.PP
		1781	.Vb 4
		1782	\& static gint
		1783	\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1784	\& {
		1785	\& int got_events = 0;
		1786	.Ve
		1787	.PP
		1788	.Vb 2
		1789	\& for (n = 0; n < nfds; ++n)
		1790	\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1791	.Ve
		1792	.PP
		1793	.Vb 2
		1794	\& if (timeout >= 0)
		1795	\& // create/start timer
		1796	.Ve
		1797	.PP
		1798	.Vb 2
		1799	\& // poll
		1800	\& ev_loop (EV_A_ 0);
		1801	.Ve
		1802	.PP
		1803	.Vb 3
		1804	\& // stop timer again
		1805	\& if (timeout >= 0)
		1806	\& ev_timer_stop (EV_A_ &to);
		1807	.Ve
		1808	.PP
		1809	.Vb 3
		1810	\& // stop io watchers again - their callbacks should have set
		1811	\& for (n = 0; n < nfds; ++n)
		1812	\& ev_io_stop (EV_A_ iow [n]);
		1813	.Ve
		1814	.PP
		1815	.Vb 2
		1816	\& return got_events;
		1817	\& }
		1818	.Ve
1270	.ie n .Sh """ev_embed"" \- when one backend isn't enough"	1819	.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1271	.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough"	1820	.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1272	.IX Subsection "ev_embed - when one backend isn't enough"	1821	.IX Subsection "ev_embed - when one backend isn't enough..."
1273	This is a rather advanced watcher type that lets you embed one event loop	1822	This is a rather advanced watcher type that lets you embed one event loop
1274	into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded	1823	into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded
1275	loop, other types of watchers might be handled in a delayed or incorrect	1824	loop, other types of watchers might be handled in a delayed or incorrect
1276	fashion and must not be used).	1825	fashion and must not be used).
1277	.PP	1826	.PP
…		…
1357	.IP "ev_embed_sweep (loop, ev_embed *)" 4	1906	.IP "ev_embed_sweep (loop, ev_embed *)" 4
1358	.IX Item "ev_embed_sweep (loop, ev_embed *)"	1907	.IX Item "ev_embed_sweep (loop, ev_embed *)"
1359	Make a single, non-blocking sweep over the embedded loop. This works	1908	Make a single, non-blocking sweep over the embedded loop. This works
1360	similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most	1909	similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
1361	apropriate way for embedded loops.	1910	apropriate way for embedded loops.
		1911	.IP "struct ev_loop *loop [read\-only]" 4
		1912	.IX Item "struct ev_loop *loop [read-only]"
		1913	The embedded event loop.
		1914	.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork"
		1915	.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
		1916	.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
		1917	Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
		1918	whoever is a good citizen cared to tell libev about it by calling
		1919	\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
		1920	event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
		1921	and only in the child after the fork. If whoever good citizen calling
		1922	\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
		1923	handlers will be invoked, too, of course.
		1924	.IP "ev_fork_init (ev_signal *, callback)" 4
		1925	.IX Item "ev_fork_init (ev_signal *, callback)"
		1926	Initialises and configures the fork watcher \- it has no parameters of any
		1927	kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
		1928	believe me.
1362	.SH "OTHER FUNCTIONS"	1929	.SH "OTHER FUNCTIONS"
1363	.IX Header "OTHER FUNCTIONS"	1930	.IX Header "OTHER FUNCTIONS"
1364	There are some other functions of possible interest. Described. Here. Now.	1931	There are some other functions of possible interest. Described. Here. Now.
1365	.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4	1932	.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4
1366	.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"	1933	.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
…		…
1428	.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4	1995	.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4
1429	.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library."	1996	.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library."
1430	.PD	1997	.PD
1431	.SH "\*(C+ SUPPORT"	1998	.SH "\*(C+ SUPPORT"
1432	.IX Header " SUPPORT"	1999	.IX Header " SUPPORT"
1433	\&\s-1TBD\s0.	2000	Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
		2001	you to use some convinience methods to start/stop watchers and also change
		2002	the callback model to a model using method callbacks on objects.
		2003	.PP
		2004	To use it,
		2005	.PP
		2006	.Vb 1
		2007	\& #include <ev++.h>
		2008	.Ve
		2009	.PP
		2010	This automatically includes \fIev.h\fR and puts all of its definitions (many
		2011	of them macros) into the global namespace. All \*(C+ specific things are
		2012	put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
		2013	options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
		2014	.PP
		2015	Care has been taken to keep the overhead low. The only data member the \*(C+
		2016	classes add (compared to plain C\-style watchers) is the event loop pointer
		2017	that the watcher is associated with (or no additional members at all if
		2018	you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
		2019	.PP
		2020	Currently, functions, and static and non-static member functions can be
		2021	used as callbacks. Other types should be easy to add as long as they only
		2022	need one additional pointer for context. If you need support for other
		2023	types of functors please contact the author (preferably after implementing
		2024	it).
		2025	.PP
		2026	Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
		2027	.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
		2028	.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
		2029	.IX Item "ev::READ, ev::WRITE etc."
		2030	These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc.
		2031	macros from \fIev.h\fR.
		2032	.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4
		2033	.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
		2034	.IX Item "ev::tstamp, ev::now"
		2035	Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix.
		2036	.ie n .IP """ev::io""\fR, \f(CW""ev::timer""\fR, \f(CW""ev::periodic""\fR, \f(CW""ev::idle""\fR, \f(CW""ev::sig"" etc." 4
		2037	.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4
		2038	.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc."
		2039	For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of
		2040	the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR
		2041	which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
		2042	defines by many implementations.
		2043	.Sp
		2044	All of those classes have these methods:
		2045	.RS 4
		2046	.IP "ev::TYPE::TYPE ()" 4
		2047	.IX Item "ev::TYPE::TYPE ()"
		2048	.PD 0
		2049	.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
		2050	.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
		2051	.IP "ev::TYPE::~TYPE" 4
		2052	.IX Item "ev::TYPE::~TYPE"
		2053	.PD
		2054	The constructor (optionally) takes an event loop to associate the watcher
		2055	with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
		2056	.Sp
		2057	The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
		2058	\&\f(CW\*(C`set\*(C'\fR method before starting it.
		2059	.Sp
		2060	It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
		2061	method to set a callback before you can start the watcher.
		2062	.Sp
		2063	(The reason why you have to use a method is a limitation in \*(C+ which does
		2064	not allow explicit template arguments for constructors).
		2065	.Sp
		2066	The destructor automatically stops the watcher if it is active.
		2067	.IP "w\->set<class, &class::method> (object *)" 4
		2068	.IX Item "w->set<class, &class::method> (object *)"
		2069	This method sets the callback method to call. The method has to have a
		2070	signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
		2071	first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
		2072	parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
		2073	.Sp
		2074	This method synthesizes efficient thunking code to call your method from
		2075	the C callback that libev requires. If your compiler can inline your
		2076	callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
		2077	your compiler is good :), then the method will be fully inlined into the
		2078	thunking function, making it as fast as a direct C callback.
		2079	.Sp
		2080	Example: simple class declaration and watcher initialisation
		2081	.Sp
		2082	.Vb 4
		2083	\& struct myclass
		2084	\& {
		2085	\& void io_cb (ev::io &w, int revents) { }
		2086	\& }
		2087	.Ve
		2088	.Sp
		2089	.Vb 3
		2090	\& myclass obj;
		2091	\& ev::io iow;
		2092	\& iow.set <myclass, &myclass::io_cb> (&obj);
		2093	.Ve
		2094	.IP "w\->set<function> (void *data = 0)" 4
		2095	.IX Item "w->set<function> (void *data = 0)"
		2096	Also sets a callback, but uses a static method or plain function as
		2097	callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
		2098	\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
		2099	.Sp
		2100	The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
		2101	.Sp
		2102	See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
		2103	.Sp
		2104	Example:
		2105	.Sp
		2106	.Vb 2
		2107	\& static void io_cb (ev::io &w, int revents) { }
		2108	\& iow.set <io_cb> ();
		2109	.Ve
		2110	.IP "w\->set (struct ev_loop *)" 4
		2111	.IX Item "w->set (struct ev_loop *)"
		2112	Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
		2113	do this when the watcher is inactive (and not pending either).
		2114	.IP "w\->set ([args])" 4
		2115	.IX Item "w->set ([args])"
		2116	Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
		2117	called at least once. Unlike the C counterpart, an active watcher gets
		2118	automatically stopped and restarted when reconfiguring it with this
		2119	method.
		2120	.IP "w\->start ()" 4
		2121	.IX Item "w->start ()"
		2122	Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
		2123	constructor already stores the event loop.
		2124	.IP "w\->stop ()" 4
		2125	.IX Item "w->stop ()"
		2126	Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
		2127	.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
		2128	.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
		2129	.IX Item "w->again () ev::timer, ev::periodic only"
		2130	For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
		2131	\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
		2132	.ie n .IP "w\->sweep () ""ev::embed"" only" 4
		2133	.el .IP "w\->sweep () \f(CWev::embed\fR only" 4
		2134	.IX Item "w->sweep () ev::embed only"
		2135	Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
		2136	.ie n .IP "w\->update () ""ev::stat"" only" 4
		2137	.el .IP "w\->update () \f(CWev::stat\fR only" 4
		2138	.IX Item "w->update () ev::stat only"
		2139	Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
		2140	.RE
		2141	.RS 4
		2142	.RE
		2143	.PP
		2144	Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
		2145	the constructor.
		2146	.PP
		2147	.Vb 4
		2148	\& class myclass
		2149	\& {
		2150	\& ev_io io; void io_cb (ev::io &w, int revents);
		2151	\& ev_idle idle void idle_cb (ev::idle &w, int revents);
		2152	.Ve
		2153	.PP
		2154	.Vb 2
		2155	\& myclass ();
		2156	\& }
		2157	.Ve
		2158	.PP
		2159	.Vb 4
		2160	\& myclass::myclass (int fd)
		2161	\& {
		2162	\& io .set <myclass, &myclass::io_cb > (this);
		2163	\& idle.set <myclass, &myclass::idle_cb> (this);
		2164	.Ve
		2165	.PP
		2166	.Vb 2
		2167	\& io.start (fd, ev::READ);
		2168	\& }
		2169	.Ve
		2170	.SH "MACRO MAGIC"
		2171	.IX Header "MACRO MAGIC"
		2172	Libev can be compiled with a variety of options, the most fundemantal is
		2173	\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and
		2174	callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
		2175	.PP
		2176	To make it easier to write programs that cope with either variant, the
		2177	following macros are defined:
		2178	.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
		2179	.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
		2180	.IX Item "EV_A, EV_A_"
		2181	This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
		2182	loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
		2183	\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
		2184	.Sp
		2185	.Vb 3
		2186	\& ev_unref (EV_A);
		2187	\& ev_timer_add (EV_A_ watcher);
		2188	\& ev_loop (EV_A_ 0);
		2189	.Ve
		2190	.Sp
		2191	It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
		2192	which is often provided by the following macro.
		2193	.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4
		2194	.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
		2195	.IX Item "EV_P, EV_P_"
		2196	This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
		2197	loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
		2198	\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
		2199	.Sp
		2200	.Vb 2
		2201	\& // this is how ev_unref is being declared
		2202	\& static void ev_unref (EV_P);
		2203	.Ve
		2204	.Sp
		2205	.Vb 2
		2206	\& // this is how you can declare your typical callback
		2207	\& static void cb (EV_P_ ev_timer *w, int revents)
		2208	.Ve
		2209	.Sp
		2210	It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
		2211	suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
		2212	.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4
		2213	.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
		2214	.IX Item "EV_DEFAULT, EV_DEFAULT_"
		2215	Similar to the other two macros, this gives you the value of the default
		2216	loop, if multiple loops are supported (\*(L"ev loop default\*(R").
		2217	.PP
		2218	Example: Declare and initialise a check watcher, utilising the above
		2219	macros so it will work regardless of whether multiple loops are supported
		2220	or not.
		2221	.PP
		2222	.Vb 5
		2223	\& static void
		2224	\& check_cb (EV_P_ ev_timer *w, int revents)
		2225	\& {
		2226	\& ev_check_stop (EV_A_ w);
		2227	\& }
		2228	.Ve
		2229	.PP
		2230	.Vb 4
		2231	\& ev_check check;
		2232	\& ev_check_init (&check, check_cb);
		2233	\& ev_check_start (EV_DEFAULT_ &check);
		2234	\& ev_loop (EV_DEFAULT_ 0);
		2235	.Ve
		2236	.SH "EMBEDDING"
		2237	.IX Header "EMBEDDING"
		2238	Libev can (and often is) directly embedded into host
		2239	applications. Examples of applications that embed it include the Deliantra
		2240	Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe)
		2241	and rxvt\-unicode.
		2242	.PP
		2243	The goal is to enable you to just copy the neecssary files into your
		2244	source directory without having to change even a single line in them, so
		2245	you can easily upgrade by simply copying (or having a checked-out copy of
		2246	libev somewhere in your source tree).
		2247	.Sh "\s-1FILESETS\s0"
		2248	.IX Subsection "FILESETS"
		2249	Depending on what features you need you need to include one or more sets of files
		2250	in your app.
		2251	.PP
		2252	\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
		2253	.IX Subsection "CORE EVENT LOOP"
		2254	.PP
		2255	To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
		2256	configuration (no autoconf):
		2257	.PP
		2258	.Vb 2
		2259	\& #define EV_STANDALONE 1
		2260	\& #include "ev.c"
		2261	.Ve
		2262	.PP
		2263	This will automatically include \fIev.h\fR, too, and should be done in a
		2264	single C source file only to provide the function implementations. To use
		2265	it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best
		2266	done by writing a wrapper around \fIev.h\fR that you can include instead and
		2267	where you can put other configuration options):
		2268	.PP
		2269	.Vb 2
		2270	\& #define EV_STANDALONE 1
		2271	\& #include "ev.h"
		2272	.Ve
		2273	.PP
		2274	Both header files and implementation files can be compiled with a \*(C+
		2275	compiler (at least, thats a stated goal, and breakage will be treated
		2276	as a bug).
		2277	.PP
		2278	You need the following files in your source tree, or in a directory
		2279	in your include path (e.g. in libev/ when using \-Ilibev):
		2280	.PP
		2281	.Vb 4
		2282	\& ev.h
		2283	\& ev.c
		2284	\& ev_vars.h
		2285	\& ev_wrap.h
		2286	.Ve
		2287	.PP
		2288	.Vb 1
		2289	\& ev_win32.c required on win32 platforms only
		2290	.Ve
		2291	.PP
		2292	.Vb 5
		2293	\& ev_select.c only when select backend is enabled (which is enabled by default)
		2294	\& ev_poll.c only when poll backend is enabled (disabled by default)
		2295	\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
		2296	\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		2297	\& ev_port.c only when the solaris port backend is enabled (disabled by default)
		2298	.Ve
		2299	.PP
		2300	\&\fIev.c\fR includes the backend files directly when enabled, so you only need
		2301	to compile this single file.
		2302	.PP
		2303	\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR
		2304	.IX Subsection "LIBEVENT COMPATIBILITY API"
		2305	.PP
		2306	To include the libevent compatibility \s-1API\s0, also include:
		2307	.PP
		2308	.Vb 1
		2309	\& #include "event.c"
		2310	.Ve
		2311	.PP
		2312	in the file including \fIev.c\fR, and:
		2313	.PP
		2314	.Vb 1
		2315	\& #include "event.h"
		2316	.Ve
		2317	.PP
		2318	in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR.
		2319	.PP
		2320	You need the following additional files for this:
		2321	.PP
		2322	.Vb 2
		2323	\& event.h
		2324	\& event.c
		2325	.Ve
		2326	.PP
		2327	\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
		2328	.IX Subsection "AUTOCONF SUPPORT"
		2329	.PP
		2330	Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in
		2331	whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
		2332	\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
		2333	include \fIconfig.h\fR and configure itself accordingly.
		2334	.PP
		2335	For this of course you need the m4 file:
		2336	.PP
		2337	.Vb 1
		2338	\& libev.m4
		2339	.Ve
		2340	.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
		2341	.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
		2342	Libev can be configured via a variety of preprocessor symbols you have to define
		2343	before including any of its files. The default is not to build for multiplicity
		2344	and only include the select backend.
		2345	.IP "\s-1EV_STANDALONE\s0" 4
		2346	.IX Item "EV_STANDALONE"
		2347	Must always be \f(CW1\fR if you do not use autoconf configuration, which
		2348	keeps libev from including \fIconfig.h\fR, and it also defines dummy
		2349	implementations for some libevent functions (such as logging, which is not
		2350	supported). It will also not define any of the structs usually found in
		2351	\&\fIevent.h\fR that are not directly supported by the libev core alone.
		2352	.IP "\s-1EV_USE_MONOTONIC\s0" 4
		2353	.IX Item "EV_USE_MONOTONIC"
		2354	If defined to be \f(CW1\fR, libev will try to detect the availability of the
		2355	monotonic clock option at both compiletime and runtime. Otherwise no use
		2356	of the monotonic clock option will be attempted. If you enable this, you
		2357	usually have to link against librt or something similar. Enabling it when
		2358	the functionality isn't available is safe, though, althoguh you have
		2359	to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR
		2360	function is hiding in (often \fI\-lrt\fR).
		2361	.IP "\s-1EV_USE_REALTIME\s0" 4
		2362	.IX Item "EV_USE_REALTIME"
		2363	If defined to be \f(CW1\fR, libev will try to detect the availability of the
		2364	realtime clock option at compiletime (and assume its availability at
		2365	runtime if successful). Otherwise no use of the realtime clock option will
		2366	be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get
		2367	(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries
		2368	in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though.
		2369	.IP "\s-1EV_USE_SELECT\s0" 4
		2370	.IX Item "EV_USE_SELECT"
		2371	If undefined or defined to be \f(CW1\fR, libev will compile in support for the
		2372	\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no
		2373	other method takes over, select will be it. Otherwise the select backend
		2374	will not be compiled in.
		2375	.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4
		2376	.IX Item "EV_SELECT_USE_FD_SET"
		2377	If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR
		2378	structure. This is useful if libev doesn't compile due to a missing
		2379	\&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on
		2380	exotic systems. This usually limits the range of file descriptors to some
		2381	low limit such as 1024 or might have other limitations (winsocket only
		2382	allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might
		2383	influence the size of the \f(CW\*(C`fd_set\*(C'\fR used.
		2384	.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4
		2385	.IX Item "EV_SELECT_IS_WINSOCKET"
		2386	When defined to \f(CW1\fR, the select backend will assume that
		2387	select/socket/connect etc. don't understand file descriptors but
		2388	wants osf handles on win32 (this is the case when the select to
		2389	be used is the winsock select). This means that it will call
		2390	\&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise,
		2391	it is assumed that all these functions actually work on fds, even
		2392	on win32. Should not be defined on non\-win32 platforms.
		2393	.IP "\s-1EV_USE_POLL\s0" 4
		2394	.IX Item "EV_USE_POLL"
		2395	If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2)
		2396	backend. Otherwise it will be enabled on non\-win32 platforms. It
		2397	takes precedence over select.
		2398	.IP "\s-1EV_USE_EPOLL\s0" 4
		2399	.IX Item "EV_USE_EPOLL"
		2400	If defined to be \f(CW1\fR, libev will compile in support for the Linux
		2401	\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime,
		2402	otherwise another method will be used as fallback. This is the
		2403	preferred backend for GNU/Linux systems.
		2404	.IP "\s-1EV_USE_KQUEUE\s0" 4
		2405	.IX Item "EV_USE_KQUEUE"
		2406	If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style
		2407	\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime,
		2408	otherwise another method will be used as fallback. This is the preferred
		2409	backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only
		2410	supports some types of fds correctly (the only platform we found that
		2411	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		2412	not be used unless explicitly requested. The best way to use it is to find
		2413	out whether kqueue supports your type of fd properly and use an embedded
		2414	kqueue loop.
		2415	.IP "\s-1EV_USE_PORT\s0" 4
		2416	.IX Item "EV_USE_PORT"
		2417	If defined to be \f(CW1\fR, libev will compile in support for the Solaris
		2418	10 port style backend. Its availability will be detected at runtime,
		2419	otherwise another method will be used as fallback. This is the preferred
		2420	backend for Solaris 10 systems.
		2421	.IP "\s-1EV_USE_DEVPOLL\s0" 4
		2422	.IX Item "EV_USE_DEVPOLL"
		2423	reserved for future expansion, works like the \s-1USE\s0 symbols above.
		2424	.IP "\s-1EV_USE_INOTIFY\s0" 4
		2425	.IX Item "EV_USE_INOTIFY"
		2426	If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
		2427	interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
		2428	be detected at runtime.
		2429	.IP "\s-1EV_H\s0" 4
		2430	.IX Item "EV_H"
		2431	The name of the \fIev.h\fR header file used to include it. The default if
		2432	undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
		2433	can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
		2434	.IP "\s-1EV_CONFIG_H\s0" 4
		2435	.IX Item "EV_CONFIG_H"
		2436	If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override
		2437	\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
		2438	\&\f(CW\*(C`EV_H\*(C'\fR, above.
		2439	.IP "\s-1EV_EVENT_H\s0" 4
		2440	.IX Item "EV_EVENT_H"
		2441	Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea
		2442	of how the \fIevent.h\fR header can be found.
		2443	.IP "\s-1EV_PROTOTYPES\s0" 4
		2444	.IX Item "EV_PROTOTYPES"
		2445	If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
		2446	prototypes, but still define all the structs and other symbols. This is
		2447	occasionally useful if you want to provide your own wrapper functions
		2448	around libev functions.
		2449	.IP "\s-1EV_MULTIPLICITY\s0" 4
		2450	.IX Item "EV_MULTIPLICITY"
		2451	If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
		2452	will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
		2453	additional independent event loops. Otherwise there will be no support
		2454	for multiple event loops and there is no first event loop pointer
		2455	argument. Instead, all functions act on the single default loop.
		2456	.IP "\s-1EV_MINPRI\s0" 4
		2457	.IX Item "EV_MINPRI"
		2458	.PD 0
		2459	.IP "\s-1EV_MAXPRI\s0" 4
		2460	.IX Item "EV_MAXPRI"
		2461	.PD
		2462	The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
		2463	\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
		2464	provide for more priorities by overriding those symbols (usually defined
		2465	to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
		2466	.Sp
		2467	When doing priority-based operations, libev usually has to linearly search
		2468	all the priorities, so having many of them (hundreds) uses a lot of space
		2469	and time, so using the defaults of five priorities (\-2 .. +2) is usually
		2470	fine.
		2471	.Sp
		2472	If your embedding app does not need any priorities, defining these both to
		2473	\&\f(CW0\fR will save some memory and cpu.
		2474	.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
		2475	.IX Item "EV_PERIODIC_ENABLE"
		2476	If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
		2477	defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
		2478	code.
		2479	.IP "\s-1EV_IDLE_ENABLE\s0" 4
		2480	.IX Item "EV_IDLE_ENABLE"
		2481	If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
		2482	defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
		2483	code.
		2484	.IP "\s-1EV_EMBED_ENABLE\s0" 4
		2485	.IX Item "EV_EMBED_ENABLE"
		2486	If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
		2487	defined to be \f(CW0\fR, then they are not.
		2488	.IP "\s-1EV_STAT_ENABLE\s0" 4
		2489	.IX Item "EV_STAT_ENABLE"
		2490	If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If
		2491	defined to be \f(CW0\fR, then they are not.
		2492	.IP "\s-1EV_FORK_ENABLE\s0" 4
		2493	.IX Item "EV_FORK_ENABLE"
		2494	If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If
		2495	defined to be \f(CW0\fR, then they are not.
		2496	.IP "\s-1EV_MINIMAL\s0" 4
		2497	.IX Item "EV_MINIMAL"
		2498	If you need to shave off some kilobytes of code at the expense of some
		2499	speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override
		2500	some inlining decisions, saves roughly 30% codesize of amd64.
		2501	.IP "\s-1EV_PID_HASHSIZE\s0" 4
		2502	.IX Item "EV_PID_HASHSIZE"
		2503	\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
		2504	pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
		2505	than enough. If you need to manage thousands of children you might want to
		2506	increase this value (\fImust\fR be a power of two).
		2507	.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
		2508	.IX Item "EV_INOTIFY_HASHSIZE"
		2509	\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
		2510	inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
		2511	usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
		2512	watchers you might want to increase this value (\fImust\fR be a power of
		2513	two).
		2514	.IP "\s-1EV_COMMON\s0" 4
		2515	.IX Item "EV_COMMON"
		2516	By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
		2517	this macro to a something else you can include more and other types of
		2518	members. You have to define it each time you include one of the files,
		2519	though, and it must be identical each time.
		2520	.Sp
		2521	For example, the perl \s-1EV\s0 module uses something like this:
		2522	.Sp
		2523	.Vb 3
		2524	\& #define EV_COMMON \e
		2525	\& SV *self; /* contains this struct */ \e
		2526	\& SV *cb_sv, *fh /* note no trailing ";" */
		2527	.Ve
		2528	.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
		2529	.IX Item "EV_CB_DECLARE (type)"
		2530	.PD 0
		2531	.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
		2532	.IX Item "EV_CB_INVOKE (watcher, revents)"
		2533	.IP "ev_set_cb (ev, cb)" 4
		2534	.IX Item "ev_set_cb (ev, cb)"
		2535	.PD
		2536	Can be used to change the callback member declaration in each watcher,
		2537	and the way callbacks are invoked and set. Must expand to a struct member
		2538	definition and a statement, respectively. See the \fIev.v\fR header file for
		2539	their default definitions. One possible use for overriding these is to
		2540	avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
		2541	method calls instead of plain function calls in \*(C+.
		2542	.Sh "\s-1EXAMPLES\s0"
		2543	.IX Subsection "EXAMPLES"
		2544	For a real-world example of a program the includes libev
		2545	verbatim, you can have a look at the \s-1EV\s0 perl module
		2546	(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
		2547	the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
		2548	interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
		2549	will be compiled. It is pretty complex because it provides its own header
		2550	file.
		2551	.Sp
		2552	The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
		2553	that everybody includes and which overrides some configure choices:
		2554	.Sp
		2555	.Vb 9
		2556	\& #define EV_MINIMAL 1
		2557	\& #define EV_USE_POLL 0
		2558	\& #define EV_MULTIPLICITY 0
		2559	\& #define EV_PERIODIC_ENABLE 0
		2560	\& #define EV_STAT_ENABLE 0
		2561	\& #define EV_FORK_ENABLE 0
		2562	\& #define EV_CONFIG_H <config.h>
		2563	\& #define EV_MINPRI 0
		2564	\& #define EV_MAXPRI 0
		2565	.Ve
		2566	.Sp
		2567	.Vb 1
		2568	\& #include "ev++.h"
		2569	.Ve
		2570	.Sp
		2571	And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled:
		2572	.Sp
		2573	.Vb 2
		2574	\& #include "ev_cpp.h"
		2575	\& #include "ev.c"
		2576	.Ve
		2577	.SH "COMPLEXITIES"
		2578	.IX Header "COMPLEXITIES"
		2579	In this section the complexities of (many of) the algorithms used inside
		2580	libev will be explained. For complexity discussions about backends see the
		2581	documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
		2582	.Sp
		2583	All of the following are about amortised time: If an array needs to be
		2584	extended, libev needs to realloc and move the whole array, but this
		2585	happens asymptotically never with higher number of elements, so O(1) might
		2586	mean it might do a lengthy realloc operation in rare cases, but on average
		2587	it is much faster and asymptotically approaches constant time.
		2588	.RS 4
		2589	.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
		2590	.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
		2591	This means that, when you have a watcher that triggers in one hour and
		2592	there are 100 watchers that would trigger before that then inserting will
		2593	have to skip those 100 watchers.
		2594	.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
		2595	.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
		2596	That means that for changing a timer costs less than removing/adding them
		2597	as only the relative motion in the event queue has to be paid for.
		2598	.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
		2599	.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
		2600	These just add the watcher into an array or at the head of a list.
		2601	=item Stopping check/prepare/idle watchers: O(1)
		2602	.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
		2603	.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
		2604	These watchers are stored in lists then need to be walked to find the
		2605	correct watcher to remove. The lists are usually short (you don't usually
		2606	have many watchers waiting for the same fd or signal).
		2607	.IP "Finding the next timer per loop iteration: O(1)" 4
		2608	.IX Item "Finding the next timer per loop iteration: O(1)"
		2609	.PD 0
		2610	.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
		2611	.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
		2612	.PD
		2613	A change means an I/O watcher gets started or stopped, which requires
		2614	libev to recalculate its status (and possibly tell the kernel).
		2615	.IP "Activating one watcher: O(1)" 4
		2616	.IX Item "Activating one watcher: O(1)"
		2617	.PD 0
		2618	.IP "Priority handling: O(number_of_priorities)" 4
		2619	.IX Item "Priority handling: O(number_of_priorities)"
		2620	.PD
		2621	Priorities are implemented by allocating some space for each
		2622	priority. When doing priority-based operations, libev usually has to
		2623	linearly search all the priorities.
		2624	.RE
		2625	.RS 4
1434	.SH "AUTHOR"	2626	.SH "AUTHOR"
1435	.IX Header "AUTHOR"	2627	.IX Header "AUTHOR"
1436	Marc Lehmann <libev@schmorp.de>.	2628	Marc Lehmann <libev@schmorp.de>.

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