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Comparing libev/ev.3 (file contents):
Revision 1.12 by root, Sat Nov 24 07:20:42 2007 UTC vs.
Revision 1.58 by root, Sat Dec 22 16:53:56 2007 UTC

…		…
126	. ds Ae AE	126	. ds Ae AE
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 "EV 1"
132	.TH "<STANDARD INPUT>" 1 "2007-11-24" "perl v5.8.8" "User Contributed Perl Documentation"	132	.TH EV 1 "2007-12-22" "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 occurring), 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
147	(or thread) by executing the \fIevent loop\fR handler, and will then	210	(or thread) by executing the \fIevent loop\fR handler, and will then
148	communicate events via a callback mechanism.	211	communicate events via a callback mechanism.
…		…
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
177	called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases	246	called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases
178	to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on	247	to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on
179	it, you should treat it as such.	248	it, you should treat it as some floatingpoint value. Unlike the name
		249	component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences
		250	throughout libev.
180	.SH "GLOBAL FUNCTIONS"	251	.SH "GLOBAL FUNCTIONS"
181	.IX Header "GLOBAL FUNCTIONS"	252	.IX Header "GLOBAL FUNCTIONS"
182	These functions can be called anytime, even before initialising the	253	These functions can be called anytime, even before initialising the
183	library in any way.	254	library in any way.
184	.IP "ev_tstamp ev_time ()" 4	255	.IP "ev_tstamp ev_time ()" 4
185	.IX Item "ev_tstamp ev_time ()"	256	.IX Item "ev_tstamp ev_time ()"
186	Returns the current time as libev would use it. Please note that the	257	Returns the current time as libev would use it. Please note that the
187	\&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp	258	\&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp
188	you actually want to know.	259	you actually want to know.
		260	.IP "ev_sleep (ev_tstamp interval)" 4
		261	.IX Item "ev_sleep (ev_tstamp interval)"
		262	Sleep for the given interval: The current thread will be blocked until
		263	either it is interrupted or the given time interval has passed. Basically
		264	this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR.
189	.IP "int ev_version_major ()" 4	265	.IP "int ev_version_major ()" 4
190	.IX Item "int ev_version_major ()"	266	.IX Item "int ev_version_major ()"
191	.PD 0	267	.PD 0
192	.IP "int ev_version_minor ()" 4	268	.IP "int ev_version_minor ()" 4
193	.IX Item "int ev_version_minor ()"	269	.IX Item "int ev_version_minor ()"
194	.PD	270	.PD
195	You can find out the major and minor version numbers of the library	271	You can find out the major and minor \s-1ABI\s0 version numbers of the library
196	you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and	272	you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and
197	\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global	273	\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global
198	symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the	274	symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the
199	version of the library your program was compiled against.	275	version of the library your program was compiled against.
200	.Sp	276	.Sp
		277	These version numbers refer to the \s-1ABI\s0 version of the library, not the
		278	release version.
		279	.Sp
201	Usually, it's a good idea to terminate if the major versions mismatch,	280	Usually, it's a good idea to terminate if the major versions mismatch,
202	as this indicates an incompatible change. Minor versions are usually	281	as this indicates an incompatible change. Minor versions are usually
203	compatible to older versions, so a larger minor version alone is usually	282	compatible to older versions, so a larger minor version alone is usually
204	not a problem.	283	not a problem.
205	.Sp	284	.Sp
206	Example: make sure we haven't accidentally been linked against the wrong	285	Example: Make sure we haven't accidentally been linked against the wrong
207	version:	286	version.
208	.Sp	287	.Sp
209	.Vb 3	288	.Vb 3
210	\& assert (("libev version mismatch",	289	\& assert (("libev version mismatch",
211	\& ev_version_major () == EV_VERSION_MAJOR	290	\& ev_version_major () == EV_VERSION_MAJOR
212	\& && ev_version_minor () >= EV_VERSION_MINOR));	291	\& && ev_version_minor () >= EV_VERSION_MINOR));
…		…
242	recommended ones.	321	recommended ones.
243	.Sp	322	.Sp
244	See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.	323	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	324	.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
246	.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"	325	.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
247	Sets the allocation function to use (the prototype is similar to the	326	Sets the allocation function to use (the prototype is similar \- the
248	realloc C function, the semantics are identical). It is used to allocate	327	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	328	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	329	memory needs to be allocated, the library might abort or take some
251	destructive action. The default is your system realloc function.	330	potentially destructive action. The default is your system realloc
		331	function.
252	.Sp	332	.Sp
253	You could override this function in high-availability programs to, say,	333	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,	334	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.	335	or even to sleep a while and retry until some memory is available.
256	.Sp	336	.Sp
257	Example: replace the libev allocator with one that waits a bit and then	337	Example: Replace the libev allocator with one that waits a bit and then
258	retries: better than mine).	338	retries).
259	.Sp	339	.Sp
260	.Vb 6	340	.Vb 6
261	\& static void *	341	\& static void *
262	\& persistent_realloc (void *ptr, long size)	342	\& persistent_realloc (void *ptr, size_t size)
263	\& {	343	\& {
264	\& for (;;)	344	\& for (;;)
265	\& {	345	\& {
266	\& void *newptr = realloc (ptr, size);	346	\& void *newptr = realloc (ptr, size);
267	.Ve	347	.Ve
…		…
289	callback is set, then libev will expect it to remedy the sitution, no	369	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	370	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	371	requested operation, or, if the condition doesn't go away, do bad stuff
292	(such as abort).	372	(such as abort).
293	.Sp	373	.Sp
294	Example: do the same thing as libev does internally:	374	Example: This is basically the same thing that libev does internally, too.
295	.Sp	375	.Sp
296	.Vb 6	376	.Vb 6
297	\& static void	377	\& static void
298	\& fatal_error (const char *msg)	378	\& fatal_error (const char *msg)
299	\& {	379	\& {
…		…
345	or setgid) then libev will \fInot\fR look at the environment variable	425	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	426	\&\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	427	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	428	useful to try out specific backends to test their performance, or to work
349	around bugs.	429	around bugs.
		430	.ie n .IP """EVFLAG_FORKCHECK""" 4
		431	.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
		432	.IX Item "EVFLAG_FORKCHECK"
		433	Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
		434	a fork, you can also make libev check for a fork in each iteration by
		435	enabling this flag.
		436	.Sp
		437	This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
		438	and thus this might slow down your event loop if you do a lot of loop
		439	iterations and little real work, but is usually not noticeable (on my
		440	Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
		441	without a syscall and thus \fIvery\fR fast, but my Linux system also has
		442	\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
		443	.Sp
		444	The big advantage of this flag is that you can forget about fork (and
		445	forget about forgetting to tell libev about forking) when you use this
		446	flag.
		447	.Sp
		448	This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
		449	environment variable.
350	.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4	450	.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
351	.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4	451	.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
352	.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"	452	.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
353	This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as	453	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,	454	libev tries to roll its own fd_set with no limits on the number of fds,
355	but if that fails, expect a fairly low limit on the number of fds when	455	but if that fails, expect a fairly low limit on the number of fds when
356	using this backend. It doesn't scale too well (O(highest_fd)), but its usually	456	using this backend. It doesn't scale too well (O(highest_fd)), but its
357	the fastest backend for a low number of fds.	457	usually the fastest backend for a low number of (low\-numbered :) fds.
		458	.Sp
		459	To get good performance out of this backend you need a high amount of
		460	parallelity (most of the file descriptors should be busy). If you are
		461	writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many
		462	connections as possible during one iteration. You might also want to have
		463	a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of
		464	readyness notifications you get per iteration.
358	.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4	465	.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4
359	.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4	466	.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4
360	.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)"	467	.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)"
361	And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than	468	And this is your standard \fIpoll\fR\|(2) backend. It's more complicated
362	select, but handles sparse fds better and has no artificial limit on the	469	than select, but handles sparse fds better and has no artificial
363	number of fds you can use (except it will slow down considerably with a	470	limit on the number of fds you can use (except it will slow down
364	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).	471	considerably with a lot of inactive fds). It scales similarly to select,
		472	i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for
		473	performance tips.
365	.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4	474	.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
366	.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4	475	.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
367	.IX Item "EVBACKEND_EPOLL (value 4, Linux)"	476	.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
368	For few fds, this backend is a bit little slower than poll and select,	477	For few fds, this backend is a bit little slower than poll and select,
369	but it scales phenomenally better. While poll and select usually scale like	478	but it scales phenomenally better. While poll and select usually scale
370	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales	479	like O(total_fds) where n is the total number of fds (or the highest fd),
371	either O(1) or O(active_fds).	480	epoll scales either O(1) or O(active_fds). The epoll design has a number
		481	of shortcomings, such as silently dropping events in some hard-to-detect
		482	cases and rewiring a syscall per fd change, no fork support and bad
		483	support for dup.
372	.Sp	484	.Sp
373	While stopping and starting an I/O watcher in the same iteration will	485	While stopping, setting and starting an I/O watcher in the same iteration
374	result in some caching, there is still a syscall per such incident	486	will result in some caching, there is still a syscall per such incident
375	(because the fd could point to a different file description now), so its	487	(because the fd could point to a different file description now), so its
376	best to avoid that. Also, \fIdup()\fRed file descriptors might not work very	488	best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work
377	well if you register events for both fds.	489	very well if you register events for both fds.
378	.Sp	490	.Sp
379	Please note that epoll sometimes generates spurious notifications, so you	491	Please note that epoll sometimes generates spurious notifications, so you
380	need to use non-blocking I/O or other means to avoid blocking when no data	492	need to use non-blocking I/O or other means to avoid blocking when no data
381	(or space) is available.	493	(or space) is available.
		494	.Sp
		495	Best performance from this backend is achieved by not unregistering all
		496	watchers for a file descriptor until it has been closed, if possible, i.e.
		497	keep at least one watcher active per fd at all times.
		498	.Sp
		499	While nominally embeddeble in other event loops, this feature is broken in
		500	all kernel versions tested so far.
382	.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4	501	.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4
383	.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4	502	.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
384	.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"	503	.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
385	Kqueue deserves special mention, as at the time of this writing, it	504	Kqueue deserves special mention, as at the time of this writing, it
386	was broken on all BSDs except NetBSD (usually it doesn't work with	505	was broken on all BSDs except NetBSD (usually it doesn't work reliably
387	anything but sockets and pipes, except on Darwin, where of course its	506	with anything but sockets and pipes, except on Darwin, where of course
388	completely useless). For this reason its not being \*(L"autodetected\*(R"	507	it's completely useless). For this reason it's not being \*(L"autodetected\*(R"
389	unless you explicitly specify it explicitly in the flags (i.e. using	508	unless you explicitly specify it explicitly in the flags (i.e. using
390	\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR).	509	\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough)
		510	system like NetBSD.
		511	.Sp
		512	You still can embed kqueue into a normal poll or select backend and use it
		513	only for sockets (after having made sure that sockets work with kqueue on
		514	the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
391	.Sp	515	.Sp
392	It scales in the same way as the epoll backend, but the interface to the	516	It scales in the same way as the epoll backend, but the interface to the
393	kernel is more efficient (which says nothing about its actual speed, of	517	kernel is more efficient (which says nothing about its actual speed, of
394	course). While starting and stopping an I/O watcher does not cause an	518	course). While stopping, setting and starting an I/O watcher does never
395	extra syscall as with epoll, it still adds up to four event changes per	519	cause an extra syscall as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to
396	incident, so its best to avoid that.	520	two event changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it
		521	drops fds silently in similarly hard-to-detect cases.
		522	.Sp
		523	This backend usually performs well under most conditions.
		524	.Sp
		525	While nominally embeddable in other event loops, this doesn't work
		526	everywhere, so you might need to test for this. And since it is broken
		527	almost everywhere, you should only use it when you have a lot of sockets
		528	(for which it usually works), by embedding it into another event loop
		529	(e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR) and using it only for
		530	sockets.
397	.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4	531	.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
398	.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4	532	.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4
399	.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)"	533	.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)"
400	This is not implemented yet (and might never be).	534	This is not implemented yet (and might never be, unless you send me an
		535	implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets
		536	and is not embeddable, which would limit the usefulness of this backend
		537	immensely.
401	.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4	538	.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
402	.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4	539	.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
403	.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"	540	.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
404	This uses the Solaris 10 port mechanism. As with everything on Solaris,	541	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
405	it's really slow, but it still scales very well (O(active_fds)).	542	it's really slow, but it still scales very well (O(active_fds)).
406	.Sp	543	.Sp
407	Please note that solaris ports can result in a lot of spurious	544	Please note that solaris event ports can deliver a lot of spurious
408	notifications, so you need to use non-blocking I/O or other means to avoid	545	notifications, so you need to use non-blocking I/O or other means to avoid
409	blocking when no data (or space) is available.	546	blocking when no data (or space) is available.
		547	.Sp
		548	While this backend scales well, it requires one system call per active
		549	file descriptor per loop iteration. For small and medium numbers of file
		550	descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend
		551	might perform better.
410	.ie n .IP """EVBACKEND_ALL""" 4	552	.ie n .IP """EVBACKEND_ALL""" 4
411	.el .IP "\f(CWEVBACKEND_ALL\fR" 4	553	.el .IP "\f(CWEVBACKEND_ALL\fR" 4
412	.IX Item "EVBACKEND_ALL"	554	.IX Item "EVBACKEND_ALL"
413	Try all backends (even potentially broken ones that wouldn't be tried	555	Try all backends (even potentially broken ones that wouldn't be tried
414	with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as	556	with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as
415	\&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR.	557	\&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR.
		558	.Sp
		559	It is definitely not recommended to use this flag.
416	.RE	560	.RE
417	.RS 4	561	.RS 4
418	.Sp	562	.Sp
419	If one or more of these are ored into the flags value, then only these	563	If one or more of these are ored into the flags value, then only these
420	backends will be tried (in the reverse order as given here). If none are	564	backends will be tried (in the reverse order as given here). If none are
…		…
448	Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is	592	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	593	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	594	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).	595	undefined behaviour (or a failed assertion if assertions are enabled).
452	.Sp	596	.Sp
453	Example: try to create a event loop that uses epoll and nothing else.	597	Example: Try to create a event loop that uses epoll and nothing else.
454	.Sp	598	.Sp
455	.Vb 3	599	.Vb 3
456	\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	600	\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
457	\& if (!epoller)	601	\& if (!epoller)
458	\& fatal ("no epoll found here, maybe it hides under your chair");	602	\& fatal ("no epoll found here, maybe it hides under your chair");
…		…
462	Destroys the default loop again (frees all memory and kernel state	606	Destroys the default loop again (frees all memory and kernel state
463	etc.). None of the active event watchers will be stopped in the normal	607	etc.). None of the active event watchers will be stopped in the normal
464	sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your	608	sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your
465	responsibility to either stop all watchers cleanly yoursef \fIbefore\fR	609	responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
466	calling this function, or cope with the fact afterwards (which is usually	610	calling this function, or cope with the fact afterwards (which is usually
467	the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them	611	the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them
468	for example).	612	for example).
		613	.Sp
		614	Note that certain global state, such as signal state, will not be freed by
		615	this function, and related watchers (such as signal and child watchers)
		616	would need to be stopped manually.
		617	.Sp
		618	In general it is not advisable to call this function except in the
		619	rare occasion where you really need to free e.g. the signal handling
		620	pipe fds. If you need dynamically allocated loops it is better to use
		621	\&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR).
469	.IP "ev_loop_destroy (loop)" 4	622	.IP "ev_loop_destroy (loop)" 4
470	.IX Item "ev_loop_destroy (loop)"	623	.IX Item "ev_loop_destroy (loop)"
471	Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an	624	Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an
472	earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.	625	earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
473	.IP "ev_default_fork ()" 4	626	.IP "ev_default_fork ()" 4
…		…
495	.IP "ev_loop_fork (loop)" 4	648	.IP "ev_loop_fork (loop)" 4
496	.IX Item "ev_loop_fork (loop)"	649	.IX Item "ev_loop_fork (loop)"
497	Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by	650	Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
498	\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop	651	\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
499	after fork, and how you do this is entirely your own problem.	652	after fork, and how you do this is entirely your own problem.
		653	.IP "unsigned int ev_loop_count (loop)" 4
		654	.IX Item "unsigned int ev_loop_count (loop)"
		655	Returns the count of loop iterations for the loop, which is identical to
		656	the number of times libev did poll for new events. It starts at \f(CW0\fR and
		657	happily wraps around with enough iterations.
		658	.Sp
		659	This value can sometimes be useful as a generation counter of sorts (it
		660	\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
		661	\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
500	.IP "unsigned int ev_backend (loop)" 4	662	.IP "unsigned int ev_backend (loop)" 4
501	.IX Item "unsigned int ev_backend (loop)"	663	.IX Item "unsigned int ev_backend (loop)"
502	Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in	664	Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
503	use.	665	use.
504	.IP "ev_tstamp ev_now (loop)" 4	666	.IP "ev_tstamp ev_now (loop)" 4
505	.IX Item "ev_tstamp ev_now (loop)"	667	.IX Item "ev_tstamp ev_now (loop)"
506	Returns the current \*(L"event loop time\*(R", which is the time the event loop	668	Returns the current \*(L"event loop time\*(R", which is the time the event loop
507	received events and started processing them. This timestamp does not	669	received events and started processing them. This timestamp does not
508	change as long as callbacks are being processed, and this is also the base	670	change as long as callbacks are being processed, and this is also the base
509	time used for relative timers. You can treat it as the timestamp of the	671	time used for relative timers. You can treat it as the timestamp of the
510	event occuring (or more correctly, libev finding out about it).	672	event occurring (or more correctly, libev finding out about it).
511	.IP "ev_loop (loop, int flags)" 4	673	.IP "ev_loop (loop, int flags)" 4
512	.IX Item "ev_loop (loop, int flags)"	674	.IX Item "ev_loop (loop, int flags)"
513	Finally, this is it, the event handler. This function usually is called	675	Finally, this is it, the event handler. This function usually is called
514	after you initialised all your watchers and you want to start handling	676	after you initialised all your watchers and you want to start handling
515	events.	677	events.
…		…
535	libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is	697	libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
536	usually a better approach for this kind of thing.	698	usually a better approach for this kind of thing.
537	.Sp	699	.Sp
538	Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:	700	Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
539	.Sp	701	.Sp
540	.Vb 18	702	.Vb 19
		703	\& - Before the first iteration, call any pending watchers.
541	\& * If there are no active watchers (reference count is zero), return.	704	\& * If there are no active watchers (reference count is zero), return.
542	\& - Queue prepare watchers and then call all outstanding watchers.	705	\& - Queue all prepare watchers and then call all outstanding watchers.
543	\& - If we have been forked, recreate the kernel state.	706	\& - If we have been forked, recreate the kernel state.
544	\& - Update the kernel state with all outstanding changes.	707	\& - Update the kernel state with all outstanding changes.
545	\& - Update the "event loop time".	708	\& - Update the "event loop time".
546	\& - Calculate for how long to block.	709	\& - Calculate for how long to block.
547	\& - Block the process, waiting for any events.	710	\& - Block the process, waiting for any events.
…		…
556	\& be handled here by queueing them when their watcher gets executed.	719	\& be handled here by queueing them when their watcher gets executed.
557	\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	720	\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
558	\& were used, return, otherwise continue with step *.	721	\& were used, return, otherwise continue with step *.
559	.Ve	722	.Ve
560	.Sp	723	.Sp
561	Example: queue some jobs and then loop until no events are outsanding	724	Example: Queue some jobs and then loop until no events are outsanding
562	anymore.	725	anymore.
563	.Sp	726	.Sp
564	.Vb 4	727	.Vb 4
565	\& ... queue jobs here, make sure they register event watchers as long	728	\& ... queue jobs here, make sure they register event watchers as long
566	\& ... as they still have work to do (even an idle watcher will do..)	729	\& ... as they still have work to do (even an idle watcher will do..)
…		…
588	visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if	751	visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if
589	no event watchers registered by it are active. It is also an excellent	752	no event watchers registered by it are active. It is also an excellent
590	way to do this for generic recurring timers or from within third-party	753	way to do this for generic recurring timers or from within third-party
591	libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.	754	libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
592	.Sp	755	.Sp
593	Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR	756	Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
594	running when nothing else is active.	757	running when nothing else is active.
595	.Sp	758	.Sp
596	.Vb 4	759	.Vb 4
597	\& struct dv_signal exitsig;	760	\& struct ev_signal exitsig;
598	\& ev_signal_init (&exitsig, sig_cb, SIGINT);	761	\& ev_signal_init (&exitsig, sig_cb, SIGINT);
599	\& ev_signal_start (myloop, &exitsig);	762	\& ev_signal_start (loop, &exitsig);
600	\& evf_unref (myloop);	763	\& evf_unref (loop);
601	.Ve	764	.Ve
602	.Sp	765	.Sp
603	Example: for some weird reason, unregister the above signal handler again.	766	Example: For some weird reason, unregister the above signal handler again.
604	.Sp	767	.Sp
605	.Vb 2	768	.Vb 2
606	\& ev_ref (myloop);	769	\& ev_ref (loop);
607	\& ev_signal_stop (myloop, &exitsig);	770	\& ev_signal_stop (loop, &exitsig);
608	.Ve	771	.Ve
		772	.IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4
		773	.IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)"
		774	.PD 0
		775	.IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4
		776	.IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)"
		777	.PD
		778	These advanced functions influence the time that libev will spend waiting
		779	for events. Both are by default \f(CW0\fR, meaning that libev will try to
		780	invoke timer/periodic callbacks and I/O callbacks with minimum latency.
		781	.Sp
		782	Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR)
		783	allows libev to delay invocation of I/O and timer/periodic callbacks to
		784	increase efficiency of loop iterations.
		785	.Sp
		786	The background is that sometimes your program runs just fast enough to
		787	handle one (or very few) event(s) per loop iteration. While this makes
		788	the program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new
		789	events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high
		790	overhead for the actual polling but can deliver many events at once.
		791	.Sp
		792	By setting a higher \fIio collect interval\fR you allow libev to spend more
		793	time collecting I/O events, so you can handle more events per iteration,
		794	at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and
		795	\&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will
		796	introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations.
		797	.Sp
		798	Likewise, by setting a higher \fItimeout collect interval\fR you allow libev
		799	to spend more time collecting timeouts, at the expense of increased
		800	latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers
		801	will not be affected. Setting this to a non-null value will not introduce
		802	any overhead in libev.
		803	.Sp
		804	Many (busy) programs can usually benefit by setting the io collect
		805	interval to a value near \f(CW0.1\fR or so, which is often enough for
		806	interactive servers (of course not for games), likewise for timeouts. It
		807	usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR,
		808	as this approsaches the timing granularity of most systems.
609	.SH "ANATOMY OF A WATCHER"	809	.SH "ANATOMY OF A WATCHER"
610	.IX Header "ANATOMY OF A WATCHER"	810	.IX Header "ANATOMY OF A WATCHER"
611	A watcher is a structure that you create and register to record your	811	A watcher is a structure that you create and register to record your
612	interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to	812	interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
613	become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that:	813	become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that:
…		…
684	The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread.	884	The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread.
685	.ie n .IP """EV_CHILD""" 4	885	.ie n .IP """EV_CHILD""" 4
686	.el .IP "\f(CWEV_CHILD\fR" 4	886	.el .IP "\f(CWEV_CHILD\fR" 4
687	.IX Item "EV_CHILD"	887	.IX Item "EV_CHILD"
688	The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change.	888	The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change.
		889	.ie n .IP """EV_STAT""" 4
		890	.el .IP "\f(CWEV_STAT\fR" 4
		891	.IX Item "EV_STAT"
		892	The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow.
689	.ie n .IP """EV_IDLE""" 4	893	.ie n .IP """EV_IDLE""" 4
690	.el .IP "\f(CWEV_IDLE\fR" 4	894	.el .IP "\f(CWEV_IDLE\fR" 4
691	.IX Item "EV_IDLE"	895	.IX Item "EV_IDLE"
692	The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do.	896	The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do.
693	.ie n .IP """EV_PREPARE""" 4	897	.ie n .IP """EV_PREPARE""" 4
…		…
703	\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any	907	\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any
704	received events. Callbacks of both watcher types can start and stop as	908	received events. Callbacks of both watcher types can start and stop as
705	many watchers as they want, and all of them will be taken into account	909	many watchers as they want, and all of them will be taken into account
706	(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep	910	(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep
707	\&\f(CW\*(C`ev_loop\*(C'\fR from blocking).	911	\&\f(CW\*(C`ev_loop\*(C'\fR from blocking).
		912	.ie n .IP """EV_EMBED""" 4
		913	.el .IP "\f(CWEV_EMBED\fR" 4
		914	.IX Item "EV_EMBED"
		915	The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention.
		916	.ie n .IP """EV_FORK""" 4
		917	.el .IP "\f(CWEV_FORK\fR" 4
		918	.IX Item "EV_FORK"
		919	The event loop has been resumed in the child process after fork (see
		920	\&\f(CW\*(C`ev_fork\*(C'\fR).
708	.ie n .IP """EV_ERROR""" 4	921	.ie n .IP """EV_ERROR""" 4
709	.el .IP "\f(CWEV_ERROR\fR" 4	922	.el .IP "\f(CWEV_ERROR\fR" 4
710	.IX Item "EV_ERROR"	923	.IX Item "EV_ERROR"
711	An unspecified error has occured, the watcher has been stopped. This might	924	An unspecified error has occured, the watcher has been stopped. This might
712	happen because the watcher could not be properly started because libev	925	happen because the watcher could not be properly started because libev
…		…
717	Libev will usually signal a few \*(L"dummy\*(R" events together with an error,	930	Libev will usually signal a few \*(L"dummy\*(R" events together with an error,
718	for example it might indicate that a fd is readable or writable, and if	931	for example it might indicate that a fd is readable or writable, and if
719	your callbacks is well-written it can just attempt the operation and cope	932	your callbacks is well-written it can just attempt the operation and cope
720	with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded	933	with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded
721	programs, though, so beware.	934	programs, though, so beware.
722	.Sh "\s-1SUMMARY\s0 \s-1OF\s0 \s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"	935	.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
723	.IX Subsection "SUMMARY OF GENERIC WATCHER FUNCTIONS"	936	.IX Subsection "GENERIC WATCHER FUNCTIONS"
724	In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,	937	In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,
725	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.	938	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.
726	.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4	939	.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
727	.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4	940	.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
728	.IX Item "ev_init (ev_TYPE *watcher, callback)"	941	.IX Item "ev_init (ev_TYPE *watcher, callback)"
…		…
734	which rolls both calls into one.	947	which rolls both calls into one.
735	.Sp	948	.Sp
736	You can reinitialise a watcher at any time as long as it has been stopped	949	You can reinitialise a watcher at any time as long as it has been stopped
737	(or never started) and there are no pending events outstanding.	950	(or never started) and there are no pending events outstanding.
738	.Sp	951	.Sp
739	The callbakc is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher,	952	The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher,
740	int revents)\*(C'\fR.	953	int revents)\*(C'\fR.
741	.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4	954	.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4
742	.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4	955	.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4
743	.IX Item "ev_TYPE_set (ev_TYPE *, [args])"	956	.IX Item "ev_TYPE_set (ev_TYPE *, [args])"
744	This macro initialises the type-specific parts of a watcher. You need to	957	This macro initialises the type-specific parts of a watcher. You need to
…		…
777	.IP "bool ev_is_pending (ev_TYPE *watcher)" 4	990	.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
778	.IX Item "bool ev_is_pending (ev_TYPE *watcher)"	991	.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
779	Returns a true value iff the watcher is pending, (i.e. it has outstanding	992	Returns a true value iff the watcher is pending, (i.e. it has outstanding
780	events but its callback has not yet been invoked). As long as a watcher	993	events but its callback has not yet been invoked). As long as a watcher
781	is pending (but not active) you must not call an init function on it (but	994	is pending (but not active) you must not call an init function on it (but
782	\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to	995	\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
783	libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).	996	make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
		997	it).
784	.IP "callback = ev_cb (ev_TYPE *watcher)" 4	998	.IP "callback ev_cb (ev_TYPE *watcher)" 4
785	.IX Item "callback = ev_cb (ev_TYPE *watcher)"	999	.IX Item "callback ev_cb (ev_TYPE *watcher)"
786	Returns the callback currently set on the watcher.	1000	Returns the callback currently set on the watcher.
787	.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4	1001	.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
788	.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"	1002	.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
789	Change the callback. You can change the callback at virtually any time	1003	Change the callback. You can change the callback at virtually any time
790	(modulo threads).	1004	(modulo threads).
		1005	.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
		1006	.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
		1007	.PD 0
		1008	.IP "int ev_priority (ev_TYPE *watcher)" 4
		1009	.IX Item "int ev_priority (ev_TYPE *watcher)"
		1010	.PD
		1011	Set and query the priority of the watcher. The priority is a small
		1012	integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
		1013	(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
		1014	before watchers with lower priority, but priority will not keep watchers
		1015	from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
		1016	.Sp
		1017	This means that priorities are \fIonly\fR used for ordering callback
		1018	invocation after new events have been received. This is useful, for
		1019	example, to reduce latency after idling, or more often, to bind two
		1020	watchers on the same event and make sure one is called first.
		1021	.Sp
		1022	If you need to suppress invocation when higher priority events are pending
		1023	you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
		1024	.Sp
		1025	You \fImust not\fR change the priority of a watcher as long as it is active or
		1026	pending.
		1027	.Sp
		1028	The default priority used by watchers when no priority has been set is
		1029	always \f(CW0\fR, which is supposed to not be too high and not be too low :).
		1030	.Sp
		1031	Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
		1032	fine, as long as you do not mind that the priority value you query might
		1033	or might not have been adjusted to be within valid range.
		1034	.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
		1035	.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
		1036	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
		1037	\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
		1038	can deal with that fact.
		1039	.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
		1040	.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
		1041	If the watcher is pending, this function returns clears its pending status
		1042	and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
		1043	watcher isn't pending it does nothing and returns \f(CW0\fR.
791	.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"	1044	.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
792	.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"	1045	.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
793	Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change	1046	Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
794	and read at any time, libev will completely ignore it. This can be used	1047	and read at any time, libev will completely ignore it. This can be used
795	to associate arbitrary data with your watcher. If you need more data and	1048	to associate arbitrary data with your watcher. If you need more data and
…		…
816	\& struct my_io *w = (struct my_io *)w_;	1069	\& struct my_io *w = (struct my_io *)w_;
817	\& ...	1070	\& ...
818	\& }	1071	\& }
819	.Ve	1072	.Ve
820	.PP	1073	.PP
821	More interesting and less C\-conformant ways of catsing your callback type	1074	More interesting and less C\-conformant ways of casting your callback type
822	have been omitted....	1075	instead have been omitted.
		1076	.PP
		1077	Another common scenario is having some data structure with multiple
		1078	watchers:
		1079	.PP
		1080	.Vb 6
		1081	\& struct my_biggy
		1082	\& {
		1083	\& int some_data;
		1084	\& ev_timer t1;
		1085	\& ev_timer t2;
		1086	\& }
		1087	.Ve
		1088	.PP
		1089	In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
		1090	you need to use \f(CW\*(C`offsetof\*(C'\fR:
		1091	.PP
		1092	.Vb 1
		1093	\& #include <stddef.h>
		1094	.Ve
		1095	.PP
		1096	.Vb 6
		1097	\& static void
		1098	\& t1_cb (EV_P_ struct ev_timer *w, int revents)
		1099	\& {
		1100	\& struct my_biggy big = (struct my_biggy *
		1101	\& (((char *)w) - offsetof (struct my_biggy, t1));
		1102	\& }
		1103	.Ve
		1104	.PP
		1105	.Vb 6
		1106	\& static void
		1107	\& t2_cb (EV_P_ struct ev_timer *w, int revents)
		1108	\& {
		1109	\& struct my_biggy big = (struct my_biggy *
		1110	\& (((char *)w) - offsetof (struct my_biggy, t2));
		1111	\& }
		1112	.Ve
823	.SH "WATCHER TYPES"	1113	.SH "WATCHER TYPES"
824	.IX Header "WATCHER TYPES"	1114	.IX Header "WATCHER TYPES"
825	This section describes each watcher in detail, but will not repeat	1115	This section describes each watcher in detail, but will not repeat
826	information given in the last section.	1116	information given in the last section. Any initialisation/set macros,
		1117	functions and members specific to the watcher type are explained.
		1118	.PP
		1119	Members are additionally marked with either \fI[read\-only]\fR, meaning that,
		1120	while the watcher is active, you can look at the member and expect some
		1121	sensible content, but you must not modify it (you can modify it while the
		1122	watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
		1123	means you can expect it to have some sensible content while the watcher
		1124	is active, but you can also modify it. Modifying it may not do something
		1125	sensible or take immediate effect (or do anything at all), but libev will
		1126	not crash or malfunction in any way.
827	.ie n .Sh """ev_io"" \- is this file descriptor readable or writable"	1127	.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?"
828	.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable"	1128	.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?"
829	.IX Subsection "ev_io - is this file descriptor readable or writable"	1129	.IX Subsection "ev_io - is this file descriptor readable or writable?"
830	I/O watchers check whether a file descriptor is readable or writable	1130	I/O watchers check whether a file descriptor is readable or writable
831	in each iteration of the event loop (This behaviour is called	1131	in each iteration of the event loop, or, more precisely, when reading
832	level-triggering because you keep receiving events as long as the	1132	would not block the process and writing would at least be able to write
833	condition persists. Remember you can stop the watcher if you don't want to	1133	some data. This behaviour is called level-triggering because you keep
834	act on the event and neither want to receive future events).	1134	receiving events as long as the condition persists. Remember you can stop
		1135	the watcher if you don't want to act on the event and neither want to
		1136	receive future events.
835	.PP	1137	.PP
836	In general you can register as many read and/or write event watchers per	1138	In general you can register as many read and/or write event watchers per
837	fd as you want (as long as you don't confuse yourself). Setting all file	1139	fd as you want (as long as you don't confuse yourself). Setting all file
838	descriptors to non-blocking mode is also usually a good idea (but not	1140	descriptors to non-blocking mode is also usually a good idea (but not
839	required if you know what you are doing).	1141	required if you know what you are doing).
840	.PP	1142	.PP
841	You have to be careful with dup'ed file descriptors, though. Some backends	1143	You have to be careful with dup'ed file descriptors, though. Some backends
842	(the linux epoll backend is a notable example) cannot handle dup'ed file	1144	(the linux epoll backend is a notable example) cannot handle dup'ed file
843	descriptors correctly if you register interest in two or more fds pointing	1145	descriptors correctly if you register interest in two or more fds pointing
844	to the same underlying file/socket etc. description (that is, they share	1146	to the same underlying file/socket/etc. description (that is, they share
845	the same underlying \*(L"file open\*(R").	1147	the same underlying \*(L"file open\*(R").
846	.PP	1148	.PP
847	If you must do this, then force the use of a known-to-be-good backend	1149	If you must do this, then force the use of a known-to-be-good backend
848	(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and	1150	(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
849	\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).	1151	\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
		1152	.PP
		1153	Another thing you have to watch out for is that it is quite easy to
		1154	receive \*(L"spurious\*(R" readyness notifications, that is your callback might
		1155	be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block
		1156	because there is no data. Not only are some backends known to create a
		1157	lot of those (for example solaris ports), it is very easy to get into
		1158	this situation even with a relatively standard program structure. Thus
		1159	it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
		1160	\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
		1161	.PP
		1162	If you cannot run the fd in non-blocking mode (for example you should not
		1163	play around with an Xlib connection), then you have to seperately re-test
		1164	whether a file descriptor is really ready with a known-to-be good interface
		1165	such as poll (fortunately in our Xlib example, Xlib already does this on
		1166	its own, so its quite safe to use).
		1167	.PP
		1168	\fIThe special problem of disappearing file descriptors\fR
		1169	.IX Subsection "The special problem of disappearing file descriptors"
		1170	.PP
		1171	Some backends (e.g. kqueue, epoll) need to be told about closing a file
		1172	descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means,
		1173	such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file
		1174	descriptor, but when it goes away, the operating system will silently drop
		1175	this interest. If another file descriptor with the same number then is
		1176	registered with libev, there is no efficient way to see that this is, in
		1177	fact, a different file descriptor.
		1178	.PP
		1179	To avoid having to explicitly tell libev about such cases, libev follows
		1180	the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev
		1181	will assume that this is potentially a new file descriptor, otherwise
		1182	it is assumed that the file descriptor stays the same. That means that
		1183	you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the
		1184	descriptor even if the file descriptor number itself did not change.
		1185	.PP
		1186	This is how one would do it normally anyway, the important point is that
		1187	the libev application should not optimise around libev but should leave
		1188	optimisations to libev.
		1189	.PP
		1190	\fIThe special problem of dup'ed file descriptors\fR
		1191	.IX Subsection "The special problem of dup'ed file descriptors"
		1192	.PP
		1193	Some backends (e.g. epoll), cannot register events for file descriptors,
		1194	but only events for the underlying file descriptions. That menas when you
		1195	have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors and register events for them, only one
		1196	file descriptor might actually receive events.
		1197	.PP
		1198	There is no workaorund possible except not registering events
		1199	for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or to resort to
		1200	\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
		1201	.PP
		1202	\fIThe special problem of fork\fR
		1203	.IX Subsection "The special problem of fork"
		1204	.PP
		1205	Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit
		1206	useless behaviour. Libev fully supports fork, but needs to be told about
		1207	it in the child.
		1208	.PP
		1209	To support fork in your programs, you either have to call
		1210	\&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child,
		1211	enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or
		1212	\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
		1213	.PP
		1214	\fIWatcher-Specific Functions\fR
		1215	.IX Subsection "Watcher-Specific Functions"
850	.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4	1216	.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
851	.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"	1217	.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
852	.PD 0	1218	.PD 0
853	.IP "ev_io_set (ev_io *, int fd, int events)" 4	1219	.IP "ev_io_set (ev_io *, int fd, int events)" 4
854	.IX Item "ev_io_set (ev_io *, int fd, int events)"	1220	.IX Item "ev_io_set (ev_io *, int fd, int events)"
855	.PD	1221	.PD
856	Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive	1222	Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
857	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 |	1223	rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or
858	EV_WRITE\*(C'\fR to receive the given events.	1224	\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events.
859	.Sp	1225	.IP "int fd [read\-only]" 4
860	Please note that most of the more scalable backend mechanisms (for example	1226	.IX Item "int fd [read-only]"
861	epoll and solaris ports) can result in spurious readyness notifications	1227	The file descriptor being watched.
862	for file descriptors, so you practically need to use non-blocking I/O (and	1228	.IP "int events [read\-only]" 4
863	treat callback invocation as hint only), or retest separately with a safe	1229	.IX Item "int events [read-only]"
864	interface before doing I/O (XLib can do this), or force the use of either	1230	The events being watched.
865	\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR, which don't suffer from this
866	problem. Also note that it is quite easy to have your callback invoked
867	when the readyness condition is no longer valid even when employing
868	typical ways of handling events, so its a good idea to use non-blocking
869	I/O unconditionally.
870	.PP	1231	.PP
871	Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well	1232	Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
872	readable, but only once. Since it is likely line\-buffered, you could	1233	readable, but only once. Since it is likely line\-buffered, you could
873	attempt to read a whole line in the callback:	1234	attempt to read a whole line in the callback.
874	.PP	1235	.PP
875	.Vb 6	1236	.Vb 6
876	\& static void	1237	\& static void
877	\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1238	\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
878	\& {	1239	\& {
…		…
887	\& struct ev_io stdin_readable;	1248	\& struct ev_io stdin_readable;
888	\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1249	\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
889	\& ev_io_start (loop, &stdin_readable);	1250	\& ev_io_start (loop, &stdin_readable);
890	\& ev_loop (loop, 0);	1251	\& ev_loop (loop, 0);
891	.Ve	1252	.Ve
892	.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts"	1253	.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
893	.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts"	1254	.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
894	.IX Subsection "ev_timer - relative and optionally recurring timeouts"	1255	.IX Subsection "ev_timer - relative and optionally repeating timeouts"
895	Timer watchers are simple relative timers that generate an event after a	1256	Timer watchers are simple relative timers that generate an event after a
896	given time, and optionally repeating in regular intervals after that.	1257	given time, and optionally repeating in regular intervals after that.
897	.PP	1258	.PP
898	The timers are based on real time, that is, if you register an event that	1259	The timers are based on real time, that is, if you register an event that
899	times out after an hour and you reset your system clock to last years	1260	times out after an hour and you reset your system clock to last years
…		…
912	.Ve	1273	.Ve
913	.PP	1274	.PP
914	The callback is guarenteed to be invoked only when its timeout has passed,	1275	The callback is guarenteed to be invoked only when its timeout has passed,
915	but if multiple timers become ready during the same loop iteration then	1276	but if multiple timers become ready during the same loop iteration then
916	order of execution is undefined.	1277	order of execution is undefined.
		1278	.PP
		1279	\fIWatcher-Specific Functions and Data Members\fR
		1280	.IX Subsection "Watcher-Specific Functions and Data Members"
917	.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4	1281	.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4
918	.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"	1282	.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
919	.PD 0	1283	.PD 0
920	.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4	1284	.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4
921	.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"	1285	.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"
…		…
933	.IP "ev_timer_again (loop)" 4	1297	.IP "ev_timer_again (loop)" 4
934	.IX Item "ev_timer_again (loop)"	1298	.IX Item "ev_timer_again (loop)"
935	This will act as if the timer timed out and restart it again if it is	1299	This will act as if the timer timed out and restart it again if it is
936	repeating. The exact semantics are:	1300	repeating. The exact semantics are:
937	.Sp	1301	.Sp
		1302	If the timer is pending, its pending status is cleared.
		1303	.Sp
938	If the timer is started but nonrepeating, stop it.	1304	If the timer is started but nonrepeating, stop it (as if it timed out).
939	.Sp	1305	.Sp
940	If the timer is repeating, either start it if necessary (with the repeat	1306	If the timer is repeating, either start it if necessary (with the
941	value), or reset the running timer to the repeat value.	1307	\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
942	.Sp	1308	.Sp
943	This sounds a bit complicated, but here is a useful and typical	1309	This sounds a bit complicated, but here is a useful and typical
944	example: Imagine you have a tcp connection and you want a so-called idle	1310	example: Imagine you have a tcp connection and you want a so-called idle
945	timeout, that is, you want to be called when there have been, say, 60	1311	timeout, that is, you want to be called when there have been, say, 60
946	seconds of inactivity on the socket. The easiest way to do this is to	1312	seconds of inactivity on the socket. The easiest way to do this is to
947	configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each	1313	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
948	time you successfully read or write some data. If you go into an idle	1314	\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
949	state where you do not expect data to travel on the socket, you can stop	1315	you go into an idle state where you do not expect data to travel on the
950	the timer, and again will automatically restart it if need be.	1316	socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
		1317	automatically restart it if need be.
		1318	.Sp
		1319	That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
		1320	altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
		1321	.Sp
		1322	.Vb 8
		1323	\& ev_timer_init (timer, callback, 0., 5.);
		1324	\& ev_timer_again (loop, timer);
		1325	\& ...
		1326	\& timer->again = 17.;
		1327	\& ev_timer_again (loop, timer);
		1328	\& ...
		1329	\& timer->again = 10.;
		1330	\& ev_timer_again (loop, timer);
		1331	.Ve
		1332	.Sp
		1333	This is more slightly efficient then stopping/starting the timer each time
		1334	you want to modify its timeout value.
		1335	.IP "ev_tstamp repeat [read\-write]" 4
		1336	.IX Item "ev_tstamp repeat [read-write]"
		1337	The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
		1338	or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
		1339	which is also when any modifications are taken into account.
951	.PP	1340	.PP
952	Example: create a timer that fires after 60 seconds.	1341	Example: Create a timer that fires after 60 seconds.
953	.PP	1342	.PP
954	.Vb 5	1343	.Vb 5
955	\& static void	1344	\& static void
956	\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1345	\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
957	\& {	1346	\& {
…		…
963	\& struct ev_timer mytimer;	1352	\& struct ev_timer mytimer;
964	\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1353	\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
965	\& ev_timer_start (loop, &mytimer);	1354	\& ev_timer_start (loop, &mytimer);
966	.Ve	1355	.Ve
967	.PP	1356	.PP
968	Example: create a timeout timer that times out after 10 seconds of	1357	Example: Create a timeout timer that times out after 10 seconds of
969	inactivity.	1358	inactivity.
970	.PP	1359	.PP
971	.Vb 5	1360	.Vb 5
972	\& static void	1361	\& static void
973	\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1362	\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
…		…
986	.Vb 3	1375	.Vb 3
987	\& // and in some piece of code that gets executed on any "activity":	1376	\& // and in some piece of code that gets executed on any "activity":
988	\& // reset the timeout to start ticking again at 10 seconds	1377	\& // reset the timeout to start ticking again at 10 seconds
989	\& ev_timer_again (&mytimer);	1378	\& ev_timer_again (&mytimer);
990	.Ve	1379	.Ve
991	.ie n .Sh """ev_periodic"" \- to cron or not to cron"	1380	.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
992	.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron"	1381	.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?"
993	.IX Subsection "ev_periodic - to cron or not to cron"	1382	.IX Subsection "ev_periodic - to cron or not to cron?"
994	Periodic watchers are also timers of a kind, but they are very versatile	1383	Periodic watchers are also timers of a kind, but they are very versatile
995	(and unfortunately a bit complex).	1384	(and unfortunately a bit complex).
996	.PP	1385	.PP
997	Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time)	1386	Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time)
998	but on wallclock time (absolute time). You can tell a periodic watcher	1387	but on wallclock time (absolute time). You can tell a periodic watcher
999	to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a	1388	to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
1000	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	1389	periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
1001	+ 10.>) and then reset your system clock to the last year, then it will	1390	+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
1002	take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger	1391	take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
1003	roughly 10 seconds later and of course not if you reset your system time	1392	roughly 10 seconds later).
1004	again).
1005	.PP	1393	.PP
1006	They can also be used to implement vastly more complex timers, such as	1394	They can also be used to implement vastly more complex timers, such as
1007	triggering an event on eahc midnight, local time.	1395	triggering an event on each midnight, local time or other, complicated,
		1396	rules.
1008	.PP	1397	.PP
1009	As with timers, the callback is guarenteed to be invoked only when the	1398	As with timers, the callback is guarenteed to be invoked only when the
1010	time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready	1399	time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
1011	during the same loop iteration then order of execution is undefined.	1400	during the same loop iteration then order of execution is undefined.
		1401	.PP
		1402	\fIWatcher-Specific Functions and Data Members\fR
		1403	.IX Subsection "Watcher-Specific Functions and Data Members"
1012	.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4	1404	.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
1013	.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)"	1405	.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)"
1014	.PD 0	1406	.PD 0
1015	.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4	1407	.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4
1016	.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"	1408	.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"
1017	.PD	1409	.PD
1018	Lots of arguments, lets sort it out... There are basically three modes of	1410	Lots of arguments, lets sort it out... There are basically three modes of
1019	operation, and we will explain them from simplest to complex:	1411	operation, and we will explain them from simplest to complex:
1020	.RS 4	1412	.RS 4
1021	.IP "* absolute timer (interval = reschedule_cb = 0)" 4	1413	.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
1022	.IX Item "absolute timer (interval = reschedule_cb = 0)"	1414	.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
1023	In this configuration the watcher triggers an event at the wallclock time	1415	In this configuration the watcher triggers an event at the wallclock time
1024	\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,	1416	\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
1025	that is, if it is to be run at January 1st 2011 then it will run when the	1417	that is, if it is to be run at January 1st 2011 then it will run when the
1026	system time reaches or surpasses this time.	1418	system time reaches or surpasses this time.
1027	.IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4	1419	.IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4
1028	.IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)"	1420	.IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)"
1029	In this mode the watcher will always be scheduled to time out at the next	1421	In this mode the watcher will always be scheduled to time out at the next
1030	\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless	1422	\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
1031	of any time jumps.	1423	and then repeat, regardless of any time jumps.
1032	.Sp	1424	.Sp
1033	This can be used to create timers that do not drift with respect to system	1425	This can be used to create timers that do not drift with respect to system
1034	time:	1426	time:
1035	.Sp	1427	.Sp
1036	.Vb 1	1428	.Vb 1
…		…
1043	by 3600.	1435	by 3600.
1044	.Sp	1436	.Sp
1045	Another way to think about it (for the mathematically inclined) is that	1437	Another way to think about it (for the mathematically inclined) is that
1046	\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible	1438	\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
1047	time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.	1439	time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
		1440	.Sp
		1441	For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
		1442	\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
		1443	this value.
1048	.IP "* manual reschedule mode (reschedule_cb = callback)" 4	1444	.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
1049	.IX Item "manual reschedule mode (reschedule_cb = callback)"	1445	.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"
1050	In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being	1446	In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
1051	ignored. Instead, each time the periodic watcher gets scheduled, the	1447	ignored. Instead, each time the periodic watcher gets scheduled, the
1052	reschedule callback will be called with the watcher as first, and the	1448	reschedule callback will be called with the watcher as first, and the
1053	current time as second argument.	1449	current time as second argument.
1054	.Sp	1450	.Sp
1055	\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,	1451	\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
1056	ever, or make any event loop modifications\fR. If you need to stop it,	1452	ever, or make any event loop modifications\fR. If you need to stop it,
1057	return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by	1453	return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by
1058	starting a prepare watcher).	1454	starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
1059	.Sp	1455	.Sp
1060	Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1456	Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1061	ev_tstamp now)\*(C'\fR, e.g.:	1457	ev_tstamp now)\*(C'\fR, e.g.:
1062	.Sp	1458	.Sp
1063	.Vb 4	1459	.Vb 4
…		…
1087	.IX Item "ev_periodic_again (loop, ev_periodic *)"	1483	.IX Item "ev_periodic_again (loop, ev_periodic *)"
1088	Simply stops and restarts the periodic watcher again. This is only useful	1484	Simply stops and restarts the periodic watcher again. This is only useful
1089	when you changed some parameters or the reschedule callback would return	1485	when you changed some parameters or the reschedule callback would return
1090	a different time than the last time it was called (e.g. in a crond like	1486	a different time than the last time it was called (e.g. in a crond like
1091	program when the crontabs have changed).	1487	program when the crontabs have changed).
		1488	.IP "ev_tstamp offset [read\-write]" 4
		1489	.IX Item "ev_tstamp offset [read-write]"
		1490	When repeating, this contains the offset value, otherwise this is the
		1491	absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR).
		1492	.Sp
		1493	Can be modified any time, but changes only take effect when the periodic
		1494	timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
		1495	.IP "ev_tstamp interval [read\-write]" 4
		1496	.IX Item "ev_tstamp interval [read-write]"
		1497	The current interval value. Can be modified any time, but changes only
		1498	take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
		1499	called.
		1500	.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
		1501	.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
		1502	The current reschedule callback, or \f(CW0\fR, if this functionality is
		1503	switched off. Can be changed any time, but changes only take effect when
		1504	the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
		1505	.IP "ev_tstamp at [read\-only]" 4
		1506	.IX Item "ev_tstamp at [read-only]"
		1507	When active, contains the absolute time that the watcher is supposed to
		1508	trigger next.
1092	.PP	1509	.PP
1093	Example: call a callback every hour, or, more precisely, whenever the	1510	Example: Call a callback every hour, or, more precisely, whenever the
1094	system clock is divisible by 3600. The callback invocation times have	1511	system clock is divisible by 3600. The callback invocation times have
1095	potentially a lot of jittering, but good long-term stability.	1512	potentially a lot of jittering, but good long-term stability.
1096	.PP	1513	.PP
1097	.Vb 5	1514	.Vb 5
1098	\& static void	1515	\& static void
…		…
1106	\& struct ev_periodic hourly_tick;	1523	\& struct ev_periodic hourly_tick;
1107	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1524	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1108	\& ev_periodic_start (loop, &hourly_tick);	1525	\& ev_periodic_start (loop, &hourly_tick);
1109	.Ve	1526	.Ve
1110	.PP	1527	.PP
1111	Example: the same as above, but use a reschedule callback to do it:	1528	Example: The same as above, but use a reschedule callback to do it:
1112	.PP	1529	.PP
1113	.Vb 1	1530	.Vb 1
1114	\& #include <math.h>	1531	\& #include <math.h>
1115	.Ve	1532	.Ve
1116	.PP	1533	.PP
…		…
1124	.PP	1541	.PP
1125	.Vb 1	1542	.Vb 1
1126	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1543	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1127	.Ve	1544	.Ve
1128	.PP	1545	.PP
1129	Example: call a callback every hour, starting now:	1546	Example: Call a callback every hour, starting now:
1130	.PP	1547	.PP
1131	.Vb 4	1548	.Vb 4
1132	\& struct ev_periodic hourly_tick;	1549	\& struct ev_periodic hourly_tick;
1133	\& ev_periodic_init (&hourly_tick, clock_cb,	1550	\& ev_periodic_init (&hourly_tick, clock_cb,
1134	\& fmod (ev_now (loop), 3600.), 3600., 0);	1551	\& fmod (ev_now (loop), 3600.), 3600., 0);
1135	\& ev_periodic_start (loop, &hourly_tick);	1552	\& ev_periodic_start (loop, &hourly_tick);
1136	.Ve	1553	.Ve
1137	.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled"	1554	.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!"
1138	.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled"	1555	.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
1139	.IX Subsection "ev_signal - signal me when a signal gets signalled"	1556	.IX Subsection "ev_signal - signal me when a signal gets signalled!"
1140	Signal watchers will trigger an event when the process receives a specific	1557	Signal watchers will trigger an event when the process receives a specific
1141	signal one or more times. Even though signals are very asynchronous, libev	1558	signal one or more times. Even though signals are very asynchronous, libev
1142	will try it's best to deliver signals synchronously, i.e. as part of the	1559	will try it's best to deliver signals synchronously, i.e. as part of the
1143	normal event processing, like any other event.	1560	normal event processing, like any other event.
1144	.PP	1561	.PP
…		…
1146	first watcher gets started will libev actually register a signal watcher	1563	first watcher gets started will libev actually register a signal watcher
1147	with the kernel (thus it coexists with your own signal handlers as long	1564	with the kernel (thus it coexists with your own signal handlers as long
1148	as you don't register any with libev). Similarly, when the last signal	1565	as you don't register any with libev). Similarly, when the last signal
1149	watcher for a signal is stopped libev will reset the signal handler to	1566	watcher for a signal is stopped libev will reset the signal handler to
1150	\&\s-1SIG_DFL\s0 (regardless of what it was set to before).	1567	\&\s-1SIG_DFL\s0 (regardless of what it was set to before).
		1568	.PP
		1569	\fIWatcher-Specific Functions and Data Members\fR
		1570	.IX Subsection "Watcher-Specific Functions and Data Members"
1151	.IP "ev_signal_init (ev_signal *, callback, int signum)" 4	1571	.IP "ev_signal_init (ev_signal *, callback, int signum)" 4
1152	.IX Item "ev_signal_init (ev_signal *, callback, int signum)"	1572	.IX Item "ev_signal_init (ev_signal *, callback, int signum)"
1153	.PD 0	1573	.PD 0
1154	.IP "ev_signal_set (ev_signal *, int signum)" 4	1574	.IP "ev_signal_set (ev_signal *, int signum)" 4
1155	.IX Item "ev_signal_set (ev_signal *, int signum)"	1575	.IX Item "ev_signal_set (ev_signal *, int signum)"
1156	.PD	1576	.PD
1157	Configures the watcher to trigger on the given signal number (usually one	1577	Configures the watcher to trigger on the given signal number (usually one
1158	of the \f(CW\*(C`SIGxxx\*(C'\fR constants).	1578	of the \f(CW\*(C`SIGxxx\*(C'\fR constants).
		1579	.IP "int signum [read\-only]" 4
		1580	.IX Item "int signum [read-only]"
		1581	The signal the watcher watches out for.
1159	.ie n .Sh """ev_child"" \- wait for pid status changes"	1582	.ie n .Sh """ev_child"" \- watch out for process status changes"
1160	.el .Sh "\f(CWev_child\fP \- wait for pid status changes"	1583	.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
1161	.IX Subsection "ev_child - wait for pid status changes"	1584	.IX Subsection "ev_child - watch out for process status changes"
1162	Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to	1585	Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
1163	some child status changes (most typically when a child of yours dies).	1586	some child status changes (most typically when a child of yours dies).
		1587	.PP
		1588	\fIWatcher-Specific Functions and Data Members\fR
		1589	.IX Subsection "Watcher-Specific Functions and Data Members"
1164	.IP "ev_child_init (ev_child *, callback, int pid)" 4	1590	.IP "ev_child_init (ev_child *, callback, int pid)" 4
1165	.IX Item "ev_child_init (ev_child *, callback, int pid)"	1591	.IX Item "ev_child_init (ev_child *, callback, int pid)"
1166	.PD 0	1592	.PD 0
1167	.IP "ev_child_set (ev_child *, int pid)" 4	1593	.IP "ev_child_set (ev_child *, int pid)" 4
1168	.IX Item "ev_child_set (ev_child *, int pid)"	1594	.IX Item "ev_child_set (ev_child *, int pid)"
…		…
1171	\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look	1597	\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look
1172	at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see	1598	at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see
1173	the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems	1599	the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems
1174	\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the	1600	\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the
1175	process causing the status change.	1601	process causing the status change.
		1602	.IP "int pid [read\-only]" 4
		1603	.IX Item "int pid [read-only]"
		1604	The process id this watcher watches out for, or \f(CW0\fR, meaning any process id.
		1605	.IP "int rpid [read\-write]" 4
		1606	.IX Item "int rpid [read-write]"
		1607	The process id that detected a status change.
		1608	.IP "int rstatus [read\-write]" 4
		1609	.IX Item "int rstatus [read-write]"
		1610	The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
		1611	\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1176	.PP	1612	.PP
1177	Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.	1613	Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1178	.PP	1614	.PP
1179	.Vb 5	1615	.Vb 5
1180	\& static void	1616	\& static void
1181	\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1617	\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1182	\& {	1618	\& {
…		…
1187	.Vb 3	1623	.Vb 3
1188	\& struct ev_signal signal_watcher;	1624	\& struct ev_signal signal_watcher;
1189	\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1625	\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1190	\& ev_signal_start (loop, &sigint_cb);	1626	\& ev_signal_start (loop, &sigint_cb);
1191	.Ve	1627	.Ve
		1628	.ie n .Sh """ev_stat"" \- did the file attributes just change?"
		1629	.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?"
		1630	.IX Subsection "ev_stat - did the file attributes just change?"
		1631	This watches a filesystem path for attribute changes. That is, it calls
		1632	\&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed
		1633	compared to the last time, invoking the callback if it did.
		1634	.PP
		1635	The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
		1636	not exist\*(R" is a status change like any other. The condition \*(L"path does
		1637	not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
		1638	otherwise always forced to be at least one) and all the other fields of
		1639	the stat buffer having unspecified contents.
		1640	.PP
		1641	The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
		1642	relative and your working directory changes, the behaviour is undefined.
		1643	.PP
		1644	Since there is no standard to do this, the portable implementation simply
		1645	calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
		1646	can specify a recommended polling interval for this case. If you specify
		1647	a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
		1648	unspecified default\fR value will be used (which you can expect to be around
		1649	five seconds, although this might change dynamically). Libev will also
		1650	impose a minimum interval which is currently around \f(CW0.1\fR, but thats
		1651	usually overkill.
		1652	.PP
		1653	This watcher type is not meant for massive numbers of stat watchers,
		1654	as even with OS-supported change notifications, this can be
		1655	resource\-intensive.
		1656	.PP
		1657	At the time of this writing, only the Linux inotify interface is
		1658	implemented (implementing kqueue support is left as an exercise for the
		1659	reader). Inotify will be used to give hints only and should not change the
		1660	semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
		1661	to fall back to regular polling again even with inotify, but changes are
		1662	usually detected immediately, and if the file exists there will be no
		1663	polling.
		1664	.PP
		1665	\fIWatcher-Specific Functions and Data Members\fR
		1666	.IX Subsection "Watcher-Specific Functions and Data Members"
		1667	.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
		1668	.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
		1669	.PD 0
		1670	.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
		1671	.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
		1672	.PD
		1673	Configures the watcher to wait for status changes of the given
		1674	\&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to
		1675	be detected and should normally be specified as \f(CW0\fR to let libev choose
		1676	a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same
		1677	path for as long as the watcher is active.
		1678	.Sp
		1679	The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected,
		1680	relative to the attributes at the time the watcher was started (or the
		1681	last change was detected).
		1682	.IP "ev_stat_stat (ev_stat *)" 4
		1683	.IX Item "ev_stat_stat (ev_stat *)"
		1684	Updates the stat buffer immediately with new values. If you change the
		1685	watched path in your callback, you could call this fucntion to avoid
		1686	detecting this change (while introducing a race condition). Can also be
		1687	useful simply to find out the new values.
		1688	.IP "ev_statdata attr [read\-only]" 4
		1689	.IX Item "ev_statdata attr [read-only]"
		1690	The most-recently detected attributes of the file. Although the type is of
		1691	\&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types
		1692	suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there
		1693	was some error while \f(CW\*(C`stat\*(C'\fRing the file.
		1694	.IP "ev_statdata prev [read\-only]" 4
		1695	.IX Item "ev_statdata prev [read-only]"
		1696	The previous attributes of the file. The callback gets invoked whenever
		1697	\&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR.
		1698	.IP "ev_tstamp interval [read\-only]" 4
		1699	.IX Item "ev_tstamp interval [read-only]"
		1700	The specified interval.
		1701	.IP "const char *path [read\-only]" 4
		1702	.IX Item "const char *path [read-only]"
		1703	The filesystem path that is being watched.
		1704	.PP
		1705	Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
		1706	.PP
		1707	.Vb 15
		1708	\& static void
		1709	\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
		1710	\& {
		1711	\& /* /etc/passwd changed in some way */
		1712	\& if (w->attr.st_nlink)
		1713	\& {
		1714	\& printf ("passwd current size %ld\en", (long)w->attr.st_size);
		1715	\& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime);
		1716	\& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime);
		1717	\& }
		1718	\& else
		1719	\& /* you shalt not abuse printf for puts */
		1720	\& puts ("wow, /etc/passwd is not there, expect problems. "
		1721	\& "if this is windows, they already arrived\en");
		1722	\& }
		1723	.Ve
		1724	.PP
		1725	.Vb 2
		1726	\& ...
		1727	\& ev_stat passwd;
		1728	.Ve
		1729	.PP
		1730	.Vb 2
		1731	\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1732	\& ev_stat_start (loop, &passwd);
		1733	.Ve
1192	.ie n .Sh """ev_idle"" \- when you've got nothing better to do"	1734	.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1193	.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do"	1735	.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1194	.IX Subsection "ev_idle - when you've got nothing better to do"	1736	.IX Subsection "ev_idle - when you've got nothing better to do..."
1195	Idle watchers trigger events when there are no other events are pending	1737	Idle watchers trigger events when no other events of the same or higher
1196	(prepare, check and other idle watchers do not count). That is, as long	1738	priority are pending (prepare, check and other idle watchers do not
1197	as your process is busy handling sockets or timeouts (or even signals,	1739	count).
1198	imagine) it will not be triggered. But when your process is idle all idle	1740	.PP
1199	watchers are being called again and again, once per event loop iteration \-	1741	That is, as long as your process is busy handling sockets or timeouts
		1742	(or even signals, imagine) of the same or higher priority it will not be
		1743	triggered. But when your process is idle (or only lower-priority watchers
		1744	are pending), the idle watchers are being called once per event loop
1200	until stopped, that is, or your process receives more events and becomes	1745	iteration \- until stopped, that is, or your process receives more events
1201	busy.	1746	and becomes busy again with higher priority stuff.
1202	.PP	1747	.PP
1203	The most noteworthy effect is that as long as any idle watchers are	1748	The most noteworthy effect is that as long as any idle watchers are
1204	active, the process will not block when waiting for new events.	1749	active, the process will not block when waiting for new events.
1205	.PP	1750	.PP
1206	Apart from keeping your process non-blocking (which is a useful	1751	Apart from keeping your process non-blocking (which is a useful
1207	effect on its own sometimes), idle watchers are a good place to do	1752	effect on its own sometimes), idle watchers are a good place to do
1208	\&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the	1753	\&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the
1209	event loop has handled all outstanding events.	1754	event loop has handled all outstanding events.
		1755	.PP
		1756	\fIWatcher-Specific Functions and Data Members\fR
		1757	.IX Subsection "Watcher-Specific Functions and Data Members"
1210	.IP "ev_idle_init (ev_signal *, callback)" 4	1758	.IP "ev_idle_init (ev_signal *, callback)" 4
1211	.IX Item "ev_idle_init (ev_signal *, callback)"	1759	.IX Item "ev_idle_init (ev_signal *, callback)"
1212	Initialises and configures the idle watcher \- it has no parameters of any	1760	Initialises and configures the idle watcher \- it has no parameters of any
1213	kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,	1761	kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1214	believe me.	1762	believe me.
1215	.PP	1763	.PP
1216	Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the	1764	Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
1217	callback, free it. Alos, use no error checking, as usual.	1765	callback, free it. Also, use no error checking, as usual.
1218	.PP	1766	.PP
1219	.Vb 7	1767	.Vb 7
1220	\& static void	1768	\& static void
1221	\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1769	\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1222	\& {	1770	\& {
…		…
1229	.Vb 3	1777	.Vb 3
1230	\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1778	\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1231	\& ev_idle_init (idle_watcher, idle_cb);	1779	\& ev_idle_init (idle_watcher, idle_cb);
1232	\& ev_idle_start (loop, idle_cb);	1780	\& ev_idle_start (loop, idle_cb);
1233	.Ve	1781	.Ve
1234	.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop"	1782	.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!"
1235	.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop"	1783	.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
1236	.IX Subsection "ev_prepare and ev_check - customise your event loop"	1784	.IX Subsection "ev_prepare and ev_check - customise your event loop!"
1237	Prepare and check watchers are usually (but not always) used in tandem:	1785	Prepare and check watchers are usually (but not always) used in tandem:
1238	prepare watchers get invoked before the process blocks and check watchers	1786	prepare watchers get invoked before the process blocks and check watchers
1239	afterwards.	1787	afterwards.
1240	.PP	1788	.PP
		1789	You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter
		1790	the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR
		1791	watchers. Other loops than the current one are fine, however. The
		1792	rationale behind this is that you do not need to check for recursion in
		1793	those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking,
		1794	\&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be
		1795	called in pairs bracketing the blocking call.
		1796	.PP
1241	Their main purpose is to integrate other event mechanisms into libev and	1797	Their main purpose is to integrate other event mechanisms into libev and
1242	their use is somewhat advanced. This could be used, for example, to track	1798	their use is somewhat advanced. This could be used, for example, to track
1243	variable changes, implement your own watchers, integrate net-snmp or a	1799	variable changes, implement your own watchers, integrate net-snmp or a
1244	coroutine library and lots more.	1800	coroutine library and lots more. They are also occasionally useful if
		1801	you cache some data and want to flush it before blocking (for example,
		1802	in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR
		1803	watcher).
1245	.PP	1804	.PP
1246	This is done by examining in each prepare call which file descriptors need	1805	This is done by examining in each prepare call which file descriptors need
1247	to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for	1806	to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for
1248	them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries	1807	them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries
1249	provide just this functionality). Then, in the check watcher you check for	1808	provide just this functionality). Then, in the check watcher you check for
…		…
1258	are ready to run (it's actually more complicated: it only runs coroutines	1817	are ready to run (it's actually more complicated: it only runs coroutines
1259	with priority higher than or equal to the event loop and one coroutine	1818	with priority higher than or equal to the event loop and one coroutine
1260	of lower priority, but only once, using idle watchers to keep the event	1819	of lower priority, but only once, using idle watchers to keep the event
1261	loop from blocking if lower-priority coroutines are active, thus mapping	1820	loop from blocking if lower-priority coroutines are active, thus mapping
1262	low-priority coroutines to idle/background tasks).	1821	low-priority coroutines to idle/background tasks).
		1822	.PP
		1823	It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
		1824	priority, to ensure that they are being run before any other watchers
		1825	after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
		1826	too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
		1827	supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers
		1828	did their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other
		1829	(non\-libev) event loops those other event loops might be in an unusable
		1830	state until their \f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to
		1831	coexist peacefully with others).
		1832	.PP
		1833	\fIWatcher-Specific Functions and Data Members\fR
		1834	.IX Subsection "Watcher-Specific Functions and Data Members"
1263	.IP "ev_prepare_init (ev_prepare *, callback)" 4	1835	.IP "ev_prepare_init (ev_prepare *, callback)" 4
1264	.IX Item "ev_prepare_init (ev_prepare *, callback)"	1836	.IX Item "ev_prepare_init (ev_prepare *, callback)"
1265	.PD 0	1837	.PD 0
1266	.IP "ev_check_init (ev_check *, callback)" 4	1838	.IP "ev_check_init (ev_check *, callback)" 4
1267	.IX Item "ev_check_init (ev_check *, callback)"	1839	.IX Item "ev_check_init (ev_check *, callback)"
1268	.PD	1840	.PD
1269	Initialises and configures the prepare or check watcher \- they have no	1841	Initialises and configures the prepare or check watcher \- they have no
1270	parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR	1842	parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1271	macros, but using them is utterly, utterly and completely pointless.	1843	macros, but using them is utterly, utterly and completely pointless.
1272	.PP	1844	.PP
1273	Example: *TODO*.	1845	There are a number of principal ways to embed other event loops or modules
		1846	into libev. Here are some ideas on how to include libadns into libev
		1847	(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
		1848	use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
		1849	embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
		1850	into the Glib event loop).
		1851	.PP
		1852	Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
		1853	and in a check watcher, destroy them and call into libadns. What follows
		1854	is pseudo-code only of course. This requires you to either use a low
		1855	priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
		1856	the callbacks for the IO/timeout watchers might not have been called yet.
		1857	.PP
		1858	.Vb 2
		1859	\& static ev_io iow [nfd];
		1860	\& static ev_timer tw;
		1861	.Ve
		1862	.PP
		1863	.Vb 4
		1864	\& static void
		1865	\& io_cb (ev_loop *loop, ev_io *w, int revents)
		1866	\& {
		1867	\& }
		1868	.Ve
		1869	.PP
		1870	.Vb 8
		1871	\& // create io watchers for each fd and a timer before blocking
		1872	\& static void
		1873	\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
		1874	\& {
		1875	\& int timeout = 3600000;
		1876	\& struct pollfd fds [nfd];
		1877	\& // actual code will need to loop here and realloc etc.
		1878	\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1879	.Ve
		1880	.PP
		1881	.Vb 3
		1882	\& /* the callback is illegal, but won't be called as we stop during check */
		1883	\& ev_timer_init (&tw, 0, timeout * 1e-3);
		1884	\& ev_timer_start (loop, &tw);
		1885	.Ve
		1886	.PP
		1887	.Vb 6
		1888	\& // create one ev_io per pollfd
		1889	\& for (int i = 0; i < nfd; ++i)
		1890	\& {
		1891	\& ev_io_init (iow + i, io_cb, fds [i].fd,
		1892	\& ((fds [i].events & POLLIN ? EV_READ : 0)
		1893	\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1894	.Ve
		1895	.PP
		1896	.Vb 4
		1897	\& fds [i].revents = 0;
		1898	\& ev_io_start (loop, iow + i);
		1899	\& }
		1900	\& }
		1901	.Ve
		1902	.PP
		1903	.Vb 5
		1904	\& // stop all watchers after blocking
		1905	\& static void
		1906	\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
		1907	\& {
		1908	\& ev_timer_stop (loop, &tw);
		1909	.Ve
		1910	.PP
		1911	.Vb 8
		1912	\& for (int i = 0; i < nfd; ++i)
		1913	\& {
		1914	\& // set the relevant poll flags
		1915	\& // could also call adns_processreadable etc. here
		1916	\& struct pollfd *fd = fds + i;
		1917	\& int revents = ev_clear_pending (iow + i);
		1918	\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1919	\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1920	.Ve
		1921	.PP
		1922	.Vb 3
		1923	\& // now stop the watcher
		1924	\& ev_io_stop (loop, iow + i);
		1925	\& }
		1926	.Ve
		1927	.PP
		1928	.Vb 2
		1929	\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1930	\& }
		1931	.Ve
		1932	.PP
		1933	Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
		1934	in the prepare watcher and would dispose of the check watcher.
		1935	.PP
		1936	Method 3: If the module to be embedded supports explicit event
		1937	notification (adns does), you can also make use of the actual watcher
		1938	callbacks, and only destroy/create the watchers in the prepare watcher.
		1939	.PP
		1940	.Vb 5
		1941	\& static void
		1942	\& timer_cb (EV_P_ ev_timer *w, int revents)
		1943	\& {
		1944	\& adns_state ads = (adns_state)w->data;
		1945	\& update_now (EV_A);
		1946	.Ve
		1947	.PP
		1948	.Vb 2
		1949	\& adns_processtimeouts (ads, &tv_now);
		1950	\& }
		1951	.Ve
		1952	.PP
		1953	.Vb 5
		1954	\& static void
		1955	\& io_cb (EV_P_ ev_io *w, int revents)
		1956	\& {
		1957	\& adns_state ads = (adns_state)w->data;
		1958	\& update_now (EV_A);
		1959	.Ve
		1960	.PP
		1961	.Vb 3
		1962	\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1963	\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1964	\& }
		1965	.Ve
		1966	.PP
		1967	.Vb 1
		1968	\& // do not ever call adns_afterpoll
		1969	.Ve
		1970	.PP
		1971	Method 4: Do not use a prepare or check watcher because the module you
		1972	want to embed is too inflexible to support it. Instead, youc na override
		1973	their poll function. The drawback with this solution is that the main
		1974	loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
		1975	this.
		1976	.PP
		1977	.Vb 4
		1978	\& static gint
		1979	\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1980	\& {
		1981	\& int got_events = 0;
		1982	.Ve
		1983	.PP
		1984	.Vb 2
		1985	\& for (n = 0; n < nfds; ++n)
		1986	\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1987	.Ve
		1988	.PP
		1989	.Vb 2
		1990	\& if (timeout >= 0)
		1991	\& // create/start timer
		1992	.Ve
		1993	.PP
		1994	.Vb 2
		1995	\& // poll
		1996	\& ev_loop (EV_A_ 0);
		1997	.Ve
		1998	.PP
		1999	.Vb 3
		2000	\& // stop timer again
		2001	\& if (timeout >= 0)
		2002	\& ev_timer_stop (EV_A_ &to);
		2003	.Ve
		2004	.PP
		2005	.Vb 3
		2006	\& // stop io watchers again - their callbacks should have set
		2007	\& for (n = 0; n < nfds; ++n)
		2008	\& ev_io_stop (EV_A_ iow [n]);
		2009	.Ve
		2010	.PP
		2011	.Vb 2
		2012	\& return got_events;
		2013	\& }
		2014	.Ve
1274	.ie n .Sh """ev_embed"" \- when one backend isn't enough"	2015	.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1275	.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough"	2016	.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1276	.IX Subsection "ev_embed - when one backend isn't enough"	2017	.IX Subsection "ev_embed - when one backend isn't enough..."
1277	This is a rather advanced watcher type that lets you embed one event loop	2018	This is a rather advanced watcher type that lets you embed one event loop
1278	into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded	2019	into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded
1279	loop, other types of watchers might be handled in a delayed or incorrect	2020	loop, other types of watchers might be handled in a delayed or incorrect
1280	fashion and must not be used).	2021	fashion and must not be used).
1281	.PP	2022	.PP
…		…
1345	\& ev_embed_start (loop_hi, &embed);	2086	\& ev_embed_start (loop_hi, &embed);
1346	\& }	2087	\& }
1347	\& else	2088	\& else
1348	\& loop_lo = loop_hi;	2089	\& loop_lo = loop_hi;
1349	.Ve	2090	.Ve
		2091	.PP
		2092	\fIWatcher-Specific Functions and Data Members\fR
		2093	.IX Subsection "Watcher-Specific Functions and Data Members"
1350	.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4	2094	.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1351	.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"	2095	.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"
1352	.PD 0	2096	.PD 0
1353	.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4	2097	.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1354	.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)"	2098	.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)"
…		…
1361	.IP "ev_embed_sweep (loop, ev_embed *)" 4	2105	.IP "ev_embed_sweep (loop, ev_embed *)" 4
1362	.IX Item "ev_embed_sweep (loop, ev_embed *)"	2106	.IX Item "ev_embed_sweep (loop, ev_embed *)"
1363	Make a single, non-blocking sweep over the embedded loop. This works	2107	Make a single, non-blocking sweep over the embedded loop. This works
1364	similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most	2108	similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
1365	apropriate way for embedded loops.	2109	apropriate way for embedded loops.
		2110	.IP "struct ev_loop *other [read\-only]" 4
		2111	.IX Item "struct ev_loop *other [read-only]"
		2112	The embedded event loop.
		2113	.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork"
		2114	.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
		2115	.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
		2116	Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
		2117	whoever is a good citizen cared to tell libev about it by calling
		2118	\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
		2119	event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
		2120	and only in the child after the fork. If whoever good citizen calling
		2121	\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
		2122	handlers will be invoked, too, of course.
		2123	.PP
		2124	\fIWatcher-Specific Functions and Data Members\fR
		2125	.IX Subsection "Watcher-Specific Functions and Data Members"
		2126	.IP "ev_fork_init (ev_signal *, callback)" 4
		2127	.IX Item "ev_fork_init (ev_signal *, callback)"
		2128	Initialises and configures the fork watcher \- it has no parameters of any
		2129	kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
		2130	believe me.
1366	.SH "OTHER FUNCTIONS"	2131	.SH "OTHER FUNCTIONS"
1367	.IX Header "OTHER FUNCTIONS"	2132	.IX Header "OTHER FUNCTIONS"
1368	There are some other functions of possible interest. Described. Here. Now.	2133	There are some other functions of possible interest. Described. Here. Now.
1369	.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4	2134	.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4
1370	.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"	2135	.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
…		…
1432	.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4	2197	.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4
1433	.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library."	2198	.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library."
1434	.PD	2199	.PD
1435	.SH "\*(C+ SUPPORT"	2200	.SH "\*(C+ SUPPORT"
1436	.IX Header " SUPPORT"	2201	.IX Header " SUPPORT"
1437	\&\s-1TBD\s0.	2202	Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
		2203	you to use some convinience methods to start/stop watchers and also change
		2204	the callback model to a model using method callbacks on objects.
		2205	.PP
		2206	To use it,
		2207	.PP
		2208	.Vb 1
		2209	\& #include <ev++.h>
		2210	.Ve
		2211	.PP
		2212	This automatically includes \fIev.h\fR and puts all of its definitions (many
		2213	of them macros) into the global namespace. All \*(C+ specific things are
		2214	put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
		2215	options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
		2216	.PP
		2217	Care has been taken to keep the overhead low. The only data member the \*(C+
		2218	classes add (compared to plain C\-style watchers) is the event loop pointer
		2219	that the watcher is associated with (or no additional members at all if
		2220	you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
		2221	.PP
		2222	Currently, functions, and static and non-static member functions can be
		2223	used as callbacks. Other types should be easy to add as long as they only
		2224	need one additional pointer for context. If you need support for other
		2225	types of functors please contact the author (preferably after implementing
		2226	it).
		2227	.PP
		2228	Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
		2229	.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
		2230	.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
		2231	.IX Item "ev::READ, ev::WRITE etc."
		2232	These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc.
		2233	macros from \fIev.h\fR.
		2234	.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4
		2235	.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
		2236	.IX Item "ev::tstamp, ev::now"
		2237	Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix.
		2238	.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
		2239	.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4
		2240	.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc."
		2241	For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of
		2242	the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR
		2243	which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
		2244	defines by many implementations.
		2245	.Sp
		2246	All of those classes have these methods:
		2247	.RS 4
		2248	.IP "ev::TYPE::TYPE ()" 4
		2249	.IX Item "ev::TYPE::TYPE ()"
		2250	.PD 0
		2251	.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
		2252	.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
		2253	.IP "ev::TYPE::~TYPE" 4
		2254	.IX Item "ev::TYPE::~TYPE"
		2255	.PD
		2256	The constructor (optionally) takes an event loop to associate the watcher
		2257	with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
		2258	.Sp
		2259	The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
		2260	\&\f(CW\*(C`set\*(C'\fR method before starting it.
		2261	.Sp
		2262	It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
		2263	method to set a callback before you can start the watcher.
		2264	.Sp
		2265	(The reason why you have to use a method is a limitation in \*(C+ which does
		2266	not allow explicit template arguments for constructors).
		2267	.Sp
		2268	The destructor automatically stops the watcher if it is active.
		2269	.IP "w\->set<class, &class::method> (object *)" 4
		2270	.IX Item "w->set<class, &class::method> (object *)"
		2271	This method sets the callback method to call. The method has to have a
		2272	signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
		2273	first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
		2274	parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
		2275	.Sp
		2276	This method synthesizes efficient thunking code to call your method from
		2277	the C callback that libev requires. If your compiler can inline your
		2278	callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
		2279	your compiler is good :), then the method will be fully inlined into the
		2280	thunking function, making it as fast as a direct C callback.
		2281	.Sp
		2282	Example: simple class declaration and watcher initialisation
		2283	.Sp
		2284	.Vb 4
		2285	\& struct myclass
		2286	\& {
		2287	\& void io_cb (ev::io &w, int revents) { }
		2288	\& }
		2289	.Ve
		2290	.Sp
		2291	.Vb 3
		2292	\& myclass obj;
		2293	\& ev::io iow;
		2294	\& iow.set <myclass, &myclass::io_cb> (&obj);
		2295	.Ve
		2296	.IP "w\->set<function> (void *data = 0)" 4
		2297	.IX Item "w->set<function> (void *data = 0)"
		2298	Also sets a callback, but uses a static method or plain function as
		2299	callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
		2300	\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
		2301	.Sp
		2302	The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
		2303	.Sp
		2304	See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
		2305	.Sp
		2306	Example:
		2307	.Sp
		2308	.Vb 2
		2309	\& static void io_cb (ev::io &w, int revents) { }
		2310	\& iow.set <io_cb> ();
		2311	.Ve
		2312	.IP "w\->set (struct ev_loop *)" 4
		2313	.IX Item "w->set (struct ev_loop *)"
		2314	Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
		2315	do this when the watcher is inactive (and not pending either).
		2316	.IP "w\->set ([args])" 4
		2317	.IX Item "w->set ([args])"
		2318	Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
		2319	called at least once. Unlike the C counterpart, an active watcher gets
		2320	automatically stopped and restarted when reconfiguring it with this
		2321	method.
		2322	.IP "w\->start ()" 4
		2323	.IX Item "w->start ()"
		2324	Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
		2325	constructor already stores the event loop.
		2326	.IP "w\->stop ()" 4
		2327	.IX Item "w->stop ()"
		2328	Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
		2329	.ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4
		2330	.el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4
		2331	.IX Item "w->again () (ev::timer, ev::periodic only)"
		2332	For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
		2333	\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
		2334	.ie n .IP "w\->sweep () (""ev::embed"" only)" 4
		2335	.el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4
		2336	.IX Item "w->sweep () (ev::embed only)"
		2337	Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
		2338	.ie n .IP "w\->update () (""ev::stat"" only)" 4
		2339	.el .IP "w\->update () (\f(CWev::stat\fR only)" 4
		2340	.IX Item "w->update () (ev::stat only)"
		2341	Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
		2342	.RE
		2343	.RS 4
		2344	.RE
		2345	.PP
		2346	Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
		2347	the constructor.
		2348	.PP
		2349	.Vb 4
		2350	\& class myclass
		2351	\& {
		2352	\& ev_io io; void io_cb (ev::io &w, int revents);
		2353	\& ev_idle idle void idle_cb (ev::idle &w, int revents);
		2354	.Ve
		2355	.PP
		2356	.Vb 2
		2357	\& myclass ();
		2358	\& }
		2359	.Ve
		2360	.PP
		2361	.Vb 4
		2362	\& myclass::myclass (int fd)
		2363	\& {
		2364	\& io .set <myclass, &myclass::io_cb > (this);
		2365	\& idle.set <myclass, &myclass::idle_cb> (this);
		2366	.Ve
		2367	.PP
		2368	.Vb 2
		2369	\& io.start (fd, ev::READ);
		2370	\& }
		2371	.Ve
		2372	.SH "MACRO MAGIC"
		2373	.IX Header "MACRO MAGIC"
		2374	Libev can be compiled with a variety of options, the most fundamantal
		2375	of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most)
		2376	functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
		2377	.PP
		2378	To make it easier to write programs that cope with either variant, the
		2379	following macros are defined:
		2380	.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
		2381	.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
		2382	.IX Item "EV_A, EV_A_"
		2383	This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
		2384	loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
		2385	\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
		2386	.Sp
		2387	.Vb 3
		2388	\& ev_unref (EV_A);
		2389	\& ev_timer_add (EV_A_ watcher);
		2390	\& ev_loop (EV_A_ 0);
		2391	.Ve
		2392	.Sp
		2393	It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
		2394	which is often provided by the following macro.
		2395	.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4
		2396	.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
		2397	.IX Item "EV_P, EV_P_"
		2398	This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
		2399	loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
		2400	\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
		2401	.Sp
		2402	.Vb 2
		2403	\& // this is how ev_unref is being declared
		2404	\& static void ev_unref (EV_P);
		2405	.Ve
		2406	.Sp
		2407	.Vb 2
		2408	\& // this is how you can declare your typical callback
		2409	\& static void cb (EV_P_ ev_timer *w, int revents)
		2410	.Ve
		2411	.Sp
		2412	It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
		2413	suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
		2414	.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4
		2415	.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
		2416	.IX Item "EV_DEFAULT, EV_DEFAULT_"
		2417	Similar to the other two macros, this gives you the value of the default
		2418	loop, if multiple loops are supported (\*(L"ev loop default\*(R").
		2419	.PP
		2420	Example: Declare and initialise a check watcher, utilising the above
		2421	macros so it will work regardless of whether multiple loops are supported
		2422	or not.
		2423	.PP
		2424	.Vb 5
		2425	\& static void
		2426	\& check_cb (EV_P_ ev_timer *w, int revents)
		2427	\& {
		2428	\& ev_check_stop (EV_A_ w);
		2429	\& }
		2430	.Ve
		2431	.PP
		2432	.Vb 4
		2433	\& ev_check check;
		2434	\& ev_check_init (&check, check_cb);
		2435	\& ev_check_start (EV_DEFAULT_ &check);
		2436	\& ev_loop (EV_DEFAULT_ 0);
		2437	.Ve
		2438	.SH "EMBEDDING"
		2439	.IX Header "EMBEDDING"
		2440	Libev can (and often is) directly embedded into host
		2441	applications. Examples of applications that embed it include the Deliantra
		2442	Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe)
		2443	and rxvt\-unicode.
		2444	.PP
		2445	The goal is to enable you to just copy the necessary files into your
		2446	source directory without having to change even a single line in them, so
		2447	you can easily upgrade by simply copying (or having a checked-out copy of
		2448	libev somewhere in your source tree).
		2449	.Sh "\s-1FILESETS\s0"
		2450	.IX Subsection "FILESETS"
		2451	Depending on what features you need you need to include one or more sets of files
		2452	in your app.
		2453	.PP
		2454	\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
		2455	.IX Subsection "CORE EVENT LOOP"
		2456	.PP
		2457	To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
		2458	configuration (no autoconf):
		2459	.PP
		2460	.Vb 2
		2461	\& #define EV_STANDALONE 1
		2462	\& #include "ev.c"
		2463	.Ve
		2464	.PP
		2465	This will automatically include \fIev.h\fR, too, and should be done in a
		2466	single C source file only to provide the function implementations. To use
		2467	it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best
		2468	done by writing a wrapper around \fIev.h\fR that you can include instead and
		2469	where you can put other configuration options):
		2470	.PP
		2471	.Vb 2
		2472	\& #define EV_STANDALONE 1
		2473	\& #include "ev.h"
		2474	.Ve
		2475	.PP
		2476	Both header files and implementation files can be compiled with a \*(C+
		2477	compiler (at least, thats a stated goal, and breakage will be treated
		2478	as a bug).
		2479	.PP
		2480	You need the following files in your source tree, or in a directory
		2481	in your include path (e.g. in libev/ when using \-Ilibev):
		2482	.PP
		2483	.Vb 4
		2484	\& ev.h
		2485	\& ev.c
		2486	\& ev_vars.h
		2487	\& ev_wrap.h
		2488	.Ve
		2489	.PP
		2490	.Vb 1
		2491	\& ev_win32.c required on win32 platforms only
		2492	.Ve
		2493	.PP
		2494	.Vb 5
		2495	\& ev_select.c only when select backend is enabled (which is enabled by default)
		2496	\& ev_poll.c only when poll backend is enabled (disabled by default)
		2497	\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
		2498	\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		2499	\& ev_port.c only when the solaris port backend is enabled (disabled by default)
		2500	.Ve
		2501	.PP
		2502	\&\fIev.c\fR includes the backend files directly when enabled, so you only need
		2503	to compile this single file.
		2504	.PP
		2505	\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR
		2506	.IX Subsection "LIBEVENT COMPATIBILITY API"
		2507	.PP
		2508	To include the libevent compatibility \s-1API\s0, also include:
		2509	.PP
		2510	.Vb 1
		2511	\& #include "event.c"
		2512	.Ve
		2513	.PP
		2514	in the file including \fIev.c\fR, and:
		2515	.PP
		2516	.Vb 1
		2517	\& #include "event.h"
		2518	.Ve
		2519	.PP
		2520	in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR.
		2521	.PP
		2522	You need the following additional files for this:
		2523	.PP
		2524	.Vb 2
		2525	\& event.h
		2526	\& event.c
		2527	.Ve
		2528	.PP
		2529	\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
		2530	.IX Subsection "AUTOCONF SUPPORT"
		2531	.PP
		2532	Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in
		2533	whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
		2534	\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
		2535	include \fIconfig.h\fR and configure itself accordingly.
		2536	.PP
		2537	For this of course you need the m4 file:
		2538	.PP
		2539	.Vb 1
		2540	\& libev.m4
		2541	.Ve
		2542	.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
		2543	.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
		2544	Libev can be configured via a variety of preprocessor symbols you have to define
		2545	before including any of its files. The default is not to build for multiplicity
		2546	and only include the select backend.
		2547	.IP "\s-1EV_STANDALONE\s0" 4
		2548	.IX Item "EV_STANDALONE"
		2549	Must always be \f(CW1\fR if you do not use autoconf configuration, which
		2550	keeps libev from including \fIconfig.h\fR, and it also defines dummy
		2551	implementations for some libevent functions (such as logging, which is not
		2552	supported). It will also not define any of the structs usually found in
		2553	\&\fIevent.h\fR that are not directly supported by the libev core alone.
		2554	.IP "\s-1EV_USE_MONOTONIC\s0" 4
		2555	.IX Item "EV_USE_MONOTONIC"
		2556	If defined to be \f(CW1\fR, libev will try to detect the availability of the
		2557	monotonic clock option at both compiletime and runtime. Otherwise no use
		2558	of the monotonic clock option will be attempted. If you enable this, you
		2559	usually have to link against librt or something similar. Enabling it when
		2560	the functionality isn't available is safe, though, although you have
		2561	to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR
		2562	function is hiding in (often \fI\-lrt\fR).
		2563	.IP "\s-1EV_USE_REALTIME\s0" 4
		2564	.IX Item "EV_USE_REALTIME"
		2565	If defined to be \f(CW1\fR, libev will try to detect the availability of the
		2566	realtime clock option at compiletime (and assume its availability at
		2567	runtime if successful). Otherwise no use of the realtime clock option will
		2568	be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get
		2569	(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the
		2570	note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though.
		2571	.IP "\s-1EV_USE_NANOSLEEP\s0" 4
		2572	.IX Item "EV_USE_NANOSLEEP"
		2573	If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available
		2574	and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR.
		2575	.IP "\s-1EV_USE_SELECT\s0" 4
		2576	.IX Item "EV_USE_SELECT"
		2577	If undefined or defined to be \f(CW1\fR, libev will compile in support for the
		2578	\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no
		2579	other method takes over, select will be it. Otherwise the select backend
		2580	will not be compiled in.
		2581	.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4
		2582	.IX Item "EV_SELECT_USE_FD_SET"
		2583	If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR
		2584	structure. This is useful if libev doesn't compile due to a missing
		2585	\&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on
		2586	exotic systems. This usually limits the range of file descriptors to some
		2587	low limit such as 1024 or might have other limitations (winsocket only
		2588	allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might
		2589	influence the size of the \f(CW\*(C`fd_set\*(C'\fR used.
		2590	.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4
		2591	.IX Item "EV_SELECT_IS_WINSOCKET"
		2592	When defined to \f(CW1\fR, the select backend will assume that
		2593	select/socket/connect etc. don't understand file descriptors but
		2594	wants osf handles on win32 (this is the case when the select to
		2595	be used is the winsock select). This means that it will call
		2596	\&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise,
		2597	it is assumed that all these functions actually work on fds, even
		2598	on win32. Should not be defined on non\-win32 platforms.
		2599	.IP "\s-1EV_USE_POLL\s0" 4
		2600	.IX Item "EV_USE_POLL"
		2601	If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2)
		2602	backend. Otherwise it will be enabled on non\-win32 platforms. It
		2603	takes precedence over select.
		2604	.IP "\s-1EV_USE_EPOLL\s0" 4
		2605	.IX Item "EV_USE_EPOLL"
		2606	If defined to be \f(CW1\fR, libev will compile in support for the Linux
		2607	\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime,
		2608	otherwise another method will be used as fallback. This is the
		2609	preferred backend for GNU/Linux systems.
		2610	.IP "\s-1EV_USE_KQUEUE\s0" 4
		2611	.IX Item "EV_USE_KQUEUE"
		2612	If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style
		2613	\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime,
		2614	otherwise another method will be used as fallback. This is the preferred
		2615	backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only
		2616	supports some types of fds correctly (the only platform we found that
		2617	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		2618	not be used unless explicitly requested. The best way to use it is to find
		2619	out whether kqueue supports your type of fd properly and use an embedded
		2620	kqueue loop.
		2621	.IP "\s-1EV_USE_PORT\s0" 4
		2622	.IX Item "EV_USE_PORT"
		2623	If defined to be \f(CW1\fR, libev will compile in support for the Solaris
		2624	10 port style backend. Its availability will be detected at runtime,
		2625	otherwise another method will be used as fallback. This is the preferred
		2626	backend for Solaris 10 systems.
		2627	.IP "\s-1EV_USE_DEVPOLL\s0" 4
		2628	.IX Item "EV_USE_DEVPOLL"
		2629	reserved for future expansion, works like the \s-1USE\s0 symbols above.
		2630	.IP "\s-1EV_USE_INOTIFY\s0" 4
		2631	.IX Item "EV_USE_INOTIFY"
		2632	If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
		2633	interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
		2634	be detected at runtime.
		2635	.IP "\s-1EV_H\s0" 4
		2636	.IX Item "EV_H"
		2637	The name of the \fIev.h\fR header file used to include it. The default if
		2638	undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
		2639	can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
		2640	.IP "\s-1EV_CONFIG_H\s0" 4
		2641	.IX Item "EV_CONFIG_H"
		2642	If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override
		2643	\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
		2644	\&\f(CW\*(C`EV_H\*(C'\fR, above.
		2645	.IP "\s-1EV_EVENT_H\s0" 4
		2646	.IX Item "EV_EVENT_H"
		2647	Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea
		2648	of how the \fIevent.h\fR header can be found.
		2649	.IP "\s-1EV_PROTOTYPES\s0" 4
		2650	.IX Item "EV_PROTOTYPES"
		2651	If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
		2652	prototypes, but still define all the structs and other symbols. This is
		2653	occasionally useful if you want to provide your own wrapper functions
		2654	around libev functions.
		2655	.IP "\s-1EV_MULTIPLICITY\s0" 4
		2656	.IX Item "EV_MULTIPLICITY"
		2657	If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
		2658	will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
		2659	additional independent event loops. Otherwise there will be no support
		2660	for multiple event loops and there is no first event loop pointer
		2661	argument. Instead, all functions act on the single default loop.
		2662	.IP "\s-1EV_MINPRI\s0" 4
		2663	.IX Item "EV_MINPRI"
		2664	.PD 0
		2665	.IP "\s-1EV_MAXPRI\s0" 4
		2666	.IX Item "EV_MAXPRI"
		2667	.PD
		2668	The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
		2669	\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
		2670	provide for more priorities by overriding those symbols (usually defined
		2671	to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
		2672	.Sp
		2673	When doing priority-based operations, libev usually has to linearly search
		2674	all the priorities, so having many of them (hundreds) uses a lot of space
		2675	and time, so using the defaults of five priorities (\-2 .. +2) is usually
		2676	fine.
		2677	.Sp
		2678	If your embedding app does not need any priorities, defining these both to
		2679	\&\f(CW0\fR will save some memory and cpu.
		2680	.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
		2681	.IX Item "EV_PERIODIC_ENABLE"
		2682	If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
		2683	defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
		2684	code.
		2685	.IP "\s-1EV_IDLE_ENABLE\s0" 4
		2686	.IX Item "EV_IDLE_ENABLE"
		2687	If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
		2688	defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
		2689	code.
		2690	.IP "\s-1EV_EMBED_ENABLE\s0" 4
		2691	.IX Item "EV_EMBED_ENABLE"
		2692	If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
		2693	defined to be \f(CW0\fR, then they are not.
		2694	.IP "\s-1EV_STAT_ENABLE\s0" 4
		2695	.IX Item "EV_STAT_ENABLE"
		2696	If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If
		2697	defined to be \f(CW0\fR, then they are not.
		2698	.IP "\s-1EV_FORK_ENABLE\s0" 4
		2699	.IX Item "EV_FORK_ENABLE"
		2700	If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If
		2701	defined to be \f(CW0\fR, then they are not.
		2702	.IP "\s-1EV_MINIMAL\s0" 4
		2703	.IX Item "EV_MINIMAL"
		2704	If you need to shave off some kilobytes of code at the expense of some
		2705	speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override
		2706	some inlining decisions, saves roughly 30% codesize of amd64.
		2707	.IP "\s-1EV_PID_HASHSIZE\s0" 4
		2708	.IX Item "EV_PID_HASHSIZE"
		2709	\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
		2710	pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
		2711	than enough. If you need to manage thousands of children you might want to
		2712	increase this value (\fImust\fR be a power of two).
		2713	.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
		2714	.IX Item "EV_INOTIFY_HASHSIZE"
		2715	\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
		2716	inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
		2717	usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
		2718	watchers you might want to increase this value (\fImust\fR be a power of
		2719	two).
		2720	.IP "\s-1EV_COMMON\s0" 4
		2721	.IX Item "EV_COMMON"
		2722	By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
		2723	this macro to a something else you can include more and other types of
		2724	members. You have to define it each time you include one of the files,
		2725	though, and it must be identical each time.
		2726	.Sp
		2727	For example, the perl \s-1EV\s0 module uses something like this:
		2728	.Sp
		2729	.Vb 3
		2730	\& #define EV_COMMON \e
		2731	\& SV *self; /* contains this struct */ \e
		2732	\& SV *cb_sv, *fh /* note no trailing ";" */
		2733	.Ve
		2734	.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
		2735	.IX Item "EV_CB_DECLARE (type)"
		2736	.PD 0
		2737	.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
		2738	.IX Item "EV_CB_INVOKE (watcher, revents)"
		2739	.IP "ev_set_cb (ev, cb)" 4
		2740	.IX Item "ev_set_cb (ev, cb)"
		2741	.PD
		2742	Can be used to change the callback member declaration in each watcher,
		2743	and the way callbacks are invoked and set. Must expand to a struct member
		2744	definition and a statement, respectively. See the \fIev.h\fR header file for
		2745	their default definitions. One possible use for overriding these is to
		2746	avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
		2747	method calls instead of plain function calls in \*(C+.
		2748	.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0"
		2749	.IX Subsection "EXPORTED API SYMBOLS"
		2750	If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of
		2751	exported symbols, you can use the provided \fISymbol.*\fR files which list
		2752	all public symbols, one per line:
		2753	.Sp
		2754	.Vb 2
		2755	\& Symbols.ev for libev proper
		2756	\& Symbols.event for the libevent emulation
		2757	.Ve
		2758	.Sp
		2759	This can also be used to rename all public symbols to avoid clashes with
		2760	multiple versions of libev linked together (which is obviously bad in
		2761	itself, but sometimes it is inconvinient to avoid this).
		2762	.Sp
		2763	A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to
		2764	include before including \fIev.h\fR:
		2765	.Sp
		2766	.Vb 1
		2767	\& <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2768	.Ve
		2769	.Sp
		2770	This would create a file \fIwrap.h\fR which essentially looks like this:
		2771	.Sp
		2772	.Vb 4
		2773	\& #define ev_backend myprefix_ev_backend
		2774	\& #define ev_check_start myprefix_ev_check_start
		2775	\& #define ev_check_stop myprefix_ev_check_stop
		2776	\& ...
		2777	.Ve
		2778	.Sh "\s-1EXAMPLES\s0"
		2779	.IX Subsection "EXAMPLES"
		2780	For a real-world example of a program the includes libev
		2781	verbatim, you can have a look at the \s-1EV\s0 perl module
		2782	(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
		2783	the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
		2784	interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
		2785	will be compiled. It is pretty complex because it provides its own header
		2786	file.
		2787	.Sp
		2788	The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
		2789	that everybody includes and which overrides some configure choices:
		2790	.Sp
		2791	.Vb 9
		2792	\& #define EV_MINIMAL 1
		2793	\& #define EV_USE_POLL 0
		2794	\& #define EV_MULTIPLICITY 0
		2795	\& #define EV_PERIODIC_ENABLE 0
		2796	\& #define EV_STAT_ENABLE 0
		2797	\& #define EV_FORK_ENABLE 0
		2798	\& #define EV_CONFIG_H <config.h>
		2799	\& #define EV_MINPRI 0
		2800	\& #define EV_MAXPRI 0
		2801	.Ve
		2802	.Sp
		2803	.Vb 1
		2804	\& #include "ev++.h"
		2805	.Ve
		2806	.Sp
		2807	And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled:
		2808	.Sp
		2809	.Vb 2
		2810	\& #include "ev_cpp.h"
		2811	\& #include "ev.c"
		2812	.Ve
		2813	.SH "COMPLEXITIES"
		2814	.IX Header "COMPLEXITIES"
		2815	In this section the complexities of (many of) the algorithms used inside
		2816	libev will be explained. For complexity discussions about backends see the
		2817	documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
		2818	.Sp
		2819	All of the following are about amortised time: If an array needs to be
		2820	extended, libev needs to realloc and move the whole array, but this
		2821	happens asymptotically never with higher number of elements, so O(1) might
		2822	mean it might do a lengthy realloc operation in rare cases, but on average
		2823	it is much faster and asymptotically approaches constant time.
		2824	.RS 4
		2825	.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
		2826	.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
		2827	This means that, when you have a watcher that triggers in one hour and
		2828	there are 100 watchers that would trigger before that then inserting will
		2829	have to skip those 100 watchers.
		2830	.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
		2831	.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
		2832	That means that for changing a timer costs less than removing/adding them
		2833	as only the relative motion in the event queue has to be paid for.
		2834	.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
		2835	.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
		2836	These just add the watcher into an array or at the head of a list.
		2837	=item Stopping check/prepare/idle watchers: O(1)
		2838	.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
		2839	.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
		2840	These watchers are stored in lists then need to be walked to find the
		2841	correct watcher to remove. The lists are usually short (you don't usually
		2842	have many watchers waiting for the same fd or signal).
		2843	.IP "Finding the next timer per loop iteration: O(1)" 4
		2844	.IX Item "Finding the next timer per loop iteration: O(1)"
		2845	.PD 0
		2846	.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
		2847	.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
		2848	.PD
		2849	A change means an I/O watcher gets started or stopped, which requires
		2850	libev to recalculate its status (and possibly tell the kernel).
		2851	.IP "Activating one watcher: O(1)" 4
		2852	.IX Item "Activating one watcher: O(1)"
		2853	.PD 0
		2854	.IP "Priority handling: O(number_of_priorities)" 4
		2855	.IX Item "Priority handling: O(number_of_priorities)"
		2856	.PD
		2857	Priorities are implemented by allocating some space for each
		2858	priority. When doing priority-based operations, libev usually has to
		2859	linearly search all the priorities.
		2860	.RE
		2861	.RS 4
1438	.SH "AUTHOR"	2862	.SH "AUTHOR"
1439	.IX Header "AUTHOR"	2863	.IX Header "AUTHOR"
1440	Marc Lehmann <libev@schmorp.de>.	2864	Marc Lehmann <libev@schmorp.de>.

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