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…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
		9	=head1 EXAMPLE PROGRAM
		10
		11	#include <ev.h>
		12
		13	ev_io stdin_watcher;
		14	ev_timer timeout_watcher;
		15
		16	/* called when data readable on stdin */
		17	static void
		18	stdin_cb (EV_P_ struct ev_io *w, int revents)
		19	{
		20	/* puts ("stdin ready"); */
		21	ev_io_stop (EV_A_ w); /* just a syntax example */
		22	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		23	}
		24
		25	static void
		26	timeout_cb (EV_P_ struct ev_timer *w, int revents)
		27	{
		28	/* puts ("timeout"); */
		29	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		30	}
		31
		32	int
		33	main (void)
		34	{
		35	struct ev_loop *loop = ev_default_loop (0);
		36
		37	/* initialise an io watcher, then start it */
		38	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
		39	ev_io_start (loop, &stdin_watcher);
		40
		41	/* simple non-repeating 5.5 second timeout */
		42	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		43	ev_timer_start (loop, &timeout_watcher);
		44
		45	/* loop till timeout or data ready */
		46	ev_loop (loop, 0);
		47
		48	return 0;
		49	}
		50
9	=head1 DESCRIPTION	51	=head1 DESCRIPTION
10		52
		53	The newest version of this document is also available as a html-formatted
		54	web page you might find easier to navigate when reading it for the first
		55	time: L<http://cvs.schmorp.de/libev/ev.html>.
		56
11	Libev is an event loop: you register interest in certain events (such as a	57	Libev is an event loop: you register interest in certain events (such as a
12	file descriptor being readable or a timeout occuring), and it will manage	58	file descriptor being readable or a timeout occurring), and it will manage
13	these event sources and provide your program with events.	59	these event sources and provide your program with events.
14		60
15	To do this, it must take more or less complete control over your process	61	To do this, it must take more or less complete control over your process
16	(or thread) by executing the I<event loop> handler, and will then	62	(or thread) by executing the I<event loop> handler, and will then
17	communicate events via a callback mechanism.	63	communicate events via a callback mechanism.
…		…
21	details of the event, and then hand it over to libev by I<starting> the	67	details of the event, and then hand it over to libev by I<starting> the
22	watcher.	68	watcher.
23		69
24	=head1 FEATURES	70	=head1 FEATURES
25		71
26	Libev supports select, poll, the linux-specific epoll and the bsd-specific	72	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
27	kqueue mechanisms for file descriptor events, relative timers, absolute	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
28	timers with customised rescheduling, signal events, process status change	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
29	events (related to SIGCHLD), and event watchers dealing with the event	75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
30	loop mechanism itself (idle, prepare and check watchers). It also is quite	76	with customised rescheduling (C<ev_periodic>), synchronous signals
		77	(C<ev_signal>), process status change events (C<ev_child>), and event
		78	watchers dealing with the event loop mechanism itself (C<ev_idle>,
		79	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
		80	file watchers (C<ev_stat>) and even limited support for fork events
		81	(C<ev_fork>).
		82
		83	It also is quite fast (see this
31	fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing	84	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
32	it to libevent for example).	85	for example).
33		86
34	=head1 CONVENTIONS	87	=head1 CONVENTIONS
35		88
36	Libev is very configurable. In this manual the default configuration	89	Libev is very configurable. In this manual the default configuration will
37	will be described, which supports multiple event loops. For more info	90	be described, which supports multiple event loops. For more info about
38	about various configuration options please have a look at the file	91	various configuration options please have a look at B<EMBED> section in
39	F<README.embed> in the libev distribution. If libev was configured without	92	this manual. If libev was configured without support for multiple event
40	support for multiple event loops, then all functions taking an initial	93	loops, then all functions taking an initial argument of name C<loop>
41	argument of name C<loop> (which is always of type C<struct ev_loop *>)	94	(which is always of type C<struct ev_loop *>) will not have this argument.
42	will not have this argument.
43		95
44	=head1 TIME REPRESENTATION	96	=head1 TIME REPRESENTATION
45		97
46	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	100	the beginning of 1970, details are complicated, don't ask). This type is
49	called C<ev_tstamp>, which is what you should use too. It usually aliases	101	called C<ev_tstamp>, which is what you should use too. It usually aliases
50	to the C<double> type in C, and when you need to do any calculations on	102	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	103	it, you should treat it as some floatingpoint value. Unlike the name
52		104	component C<stamp> might indicate, it is also used for time differences
		105	throughout libev.
53		106
54	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
55		108
56	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
57	library in any way.	110	library in any way.
…		…
66		119
67	=item int ev_version_major ()	120	=item int ev_version_major ()
68		121
69	=item int ev_version_minor ()	122	=item int ev_version_minor ()
70		123
71	You can find out the major and minor version numbers of the library	124	You can find out the major and minor ABI version numbers of the library
72	you linked against by calling the functions C<ev_version_major> and	125	you linked against by calling the functions C<ev_version_major> and
73	C<ev_version_minor>. If you want, you can compare against the global	126	C<ev_version_minor>. If you want, you can compare against the global
74	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	127	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
75	version of the library your program was compiled against.	128	version of the library your program was compiled against.
76		129
		130	These version numbers refer to the ABI version of the library, not the
		131	release version.
		132
77	Usually, it's a good idea to terminate if the major versions mismatch,	133	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	134	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	135	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	136	not a problem.
81		137
82	Example: make sure we haven't accidentally been linked against the wrong	138	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	139	version.
84		140
85	assert (("libev version mismatch",	141	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	142	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	143	&& ev_version_minor () >= EV_VERSION_MINOR));
88		144
…		…
118		174
119	See the description of C<ev_embed> watchers for more info.	175	See the description of C<ev_embed> watchers for more info.
120		176
121	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	177	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
122		178
123	Sets the allocation function to use (the prototype is similar to the	179	Sets the allocation function to use (the prototype is similar - the
124	realloc C function, the semantics are identical). It is used to allocate	180	semantics is identical - to the realloc C function). It is used to
125	and free memory (no surprises here). If it returns zero when memory	181	allocate and free memory (no surprises here). If it returns zero when
126	needs to be allocated, the library might abort or take some potentially	182	memory needs to be allocated, the library might abort or take some
127	destructive action. The default is your system realloc function.	183	potentially destructive action. The default is your system realloc
		184	function.
128		185
129	You could override this function in high-availability programs to, say,	186	You could override this function in high-availability programs to, say,
130	free some memory if it cannot allocate memory, to use a special allocator,	187	free some memory if it cannot allocate memory, to use a special allocator,
131	or even to sleep a while and retry until some memory is available.	188	or even to sleep a while and retry until some memory is available.
132		189
133	Example: replace the libev allocator with one that waits a bit and then	190	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	191	retries).
135		192
136	static void *	193	static void *
137	persistent_realloc (void *ptr, long size)	194	persistent_realloc (void *ptr, size_t size)
138	{	195	{
139	for (;;)	196	for (;;)
140	{	197	{
141	void *newptr = realloc (ptr, size);	198	void *newptr = realloc (ptr, size);
142		199
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	215	callback is set, then libev will expect it to remedy the sitution, no
159	matter what, when it returns. That is, libev will generally retry the	216	matter what, when it returns. That is, libev will generally retry the
160	requested operation, or, if the condition doesn't go away, do bad stuff	217	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	218	(such as abort).
162		219
163	Example: do the same thing as libev does internally:	220	Example: This is basically the same thing that libev does internally, too.
164		221
165	static void	222	static void
166	fatal_error (const char *msg)	223	fatal_error (const char *msg)
167	{	224	{
168	perror (msg);	225	perror (msg);
…		…
218	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	275	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
219	override the flags completely if it is found in the environment. This is	276	override the flags completely if it is found in the environment. This is
220	useful to try out specific backends to test their performance, or to work	277	useful to try out specific backends to test their performance, or to work
221	around bugs.	278	around bugs.
222		279
		280	=item C<EVFLAG_FORKCHECK>
		281
		282	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		283	a fork, you can also make libev check for a fork in each iteration by
		284	enabling this flag.
		285
		286	This works by calling C<getpid ()> on every iteration of the loop,
		287	and thus this might slow down your event loop if you do a lot of loop
		288	iterations and little real work, but is usually not noticeable (on my
		289	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		290	without a syscall and thus I<very> fast, but my Linux system also has
		291	C<pthread_atfork> which is even faster).
		292
		293	The big advantage of this flag is that you can forget about fork (and
		294	forget about forgetting to tell libev about forking) when you use this
		295	flag.
		296
		297	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		298	environment variable.
		299
223	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	300	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
224		301
225	This is your standard select(2) backend. Not I<completely> standard, as	302	This is your standard select(2) backend. Not I<completely> standard, as
226	libev tries to roll its own fd_set with no limits on the number of fds,	303	libev tries to roll its own fd_set with no limits on the number of fds,
227	but if that fails, expect a fairly low limit on the number of fds when	304	but if that fails, expect a fairly low limit on the number of fds when
…		…
254		331
255	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	332	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
256		333
257	Kqueue deserves special mention, as at the time of this writing, it	334	Kqueue deserves special mention, as at the time of this writing, it
258	was broken on all BSDs except NetBSD (usually it doesn't work with	335	was broken on all BSDs except NetBSD (usually it doesn't work with
259	anything but sockets and pipes, except on Darwin, where of course its	336	anything but sockets and pipes, except on Darwin, where of course it's
260	completely useless). For this reason its not being "autodetected"	337	completely useless). For this reason it's not being "autodetected"
261	unless you explicitly specify it explicitly in the flags (i.e. using	338	unless you explicitly specify it explicitly in the flags (i.e. using
262	C<EVBACKEND_KQUEUE>).	339	C<EVBACKEND_KQUEUE>).
263		340
264	It scales in the same way as the epoll backend, but the interface to the	341	It scales in the same way as the epoll backend, but the interface to the
265	kernel is more efficient (which says nothing about its actual speed, of	342	kernel is more efficient (which says nothing about its actual speed, of
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	391	Similar to C<ev_default_loop>, but always creates a new event loop that is
315	always distinct from the default loop. Unlike the default loop, it cannot	392	always distinct from the default loop. Unlike the default loop, it cannot
316	handle signal and child watchers, and attempts to do so will be greeted by	393	handle signal and child watchers, and attempts to do so will be greeted by
317	undefined behaviour (or a failed assertion if assertions are enabled).	394	undefined behaviour (or a failed assertion if assertions are enabled).
318		395
319	Example: try to create a event loop that uses epoll and nothing else.	396	Example: Try to create a event loop that uses epoll and nothing else.
320		397
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	398	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
322	if (!epoller)	399	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	400	fatal ("no epoll found here, maybe it hides under your chair");
324		401
…		…
327	Destroys the default loop again (frees all memory and kernel state	404	Destroys the default loop again (frees all memory and kernel state
328	etc.). None of the active event watchers will be stopped in the normal	405	etc.). None of the active event watchers will be stopped in the normal
329	sense, so e.g. C<ev_is_active> might still return true. It is your	406	sense, so e.g. C<ev_is_active> might still return true. It is your
330	responsibility to either stop all watchers cleanly yoursef I<before>	407	responsibility to either stop all watchers cleanly yoursef I<before>
331	calling this function, or cope with the fact afterwards (which is usually	408	calling this function, or cope with the fact afterwards (which is usually
332	the easiest thing, youc na just ignore the watchers and/or C<free ()> them	409	the easiest thing, you can just ignore the watchers and/or C<free ()> them
333	for example).	410	for example).
		411
		412	Note that certain global state, such as signal state, will not be freed by
		413	this function, and related watchers (such as signal and child watchers)
		414	would need to be stopped manually.
		415
		416	In general it is not advisable to call this function except in the
		417	rare occasion where you really need to free e.g. the signal handling
		418	pipe fds. If you need dynamically allocated loops it is better to use
		419	C<ev_loop_new> and C<ev_loop_destroy>).
334		420
335	=item ev_loop_destroy (loop)	421	=item ev_loop_destroy (loop)
336		422
337	Like C<ev_default_destroy>, but destroys an event loop created by an	423	Like C<ev_default_destroy>, but destroys an event loop created by an
338	earlier call to C<ev_loop_new>.	424	earlier call to C<ev_loop_new>.
…		…
362		448
363	Like C<ev_default_fork>, but acts on an event loop created by	449	Like C<ev_default_fork>, but acts on an event loop created by
364	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	450	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
365	after fork, and how you do this is entirely your own problem.	451	after fork, and how you do this is entirely your own problem.
366		452
		453	=item unsigned int ev_loop_count (loop)
		454
		455	Returns the count of loop iterations for the loop, which is identical to
		456	the number of times libev did poll for new events. It starts at C<0> and
		457	happily wraps around with enough iterations.
		458
		459	This value can sometimes be useful as a generation counter of sorts (it
		460	"ticks" the number of loop iterations), as it roughly corresponds with
		461	C<ev_prepare> and C<ev_check> calls.
		462
367	=item unsigned int ev_backend (loop)	463	=item unsigned int ev_backend (loop)
368		464
369	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	465	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
370	use.	466	use.
371		467
…		…
373		469
374	Returns the current "event loop time", which is the time the event loop	470	Returns the current "event loop time", which is the time the event loop
375	received events and started processing them. This timestamp does not	471	received events and started processing them. This timestamp does not
376	change as long as callbacks are being processed, and this is also the base	472	change as long as callbacks are being processed, and this is also the base
377	time used for relative timers. You can treat it as the timestamp of the	473	time used for relative timers. You can treat it as the timestamp of the
378	event occuring (or more correctly, libev finding out about it).	474	event occurring (or more correctly, libev finding out about it).
379		475
380	=item ev_loop (loop, int flags)	476	=item ev_loop (loop, int flags)
381		477
382	Finally, this is it, the event handler. This function usually is called	478	Finally, this is it, the event handler. This function usually is called
383	after you initialised all your watchers and you want to start handling	479	after you initialised all your watchers and you want to start handling
…		…
404	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	500	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
405	usually a better approach for this kind of thing.	501	usually a better approach for this kind of thing.
406		502
407	Here are the gory details of what C<ev_loop> does:	503	Here are the gory details of what C<ev_loop> does:
408		504
		505	- Before the first iteration, call any pending watchers.
409	* If there are no active watchers (reference count is zero), return.	506	* If there are no active watchers (reference count is zero), return.
410	- Queue prepare watchers and then call all outstanding watchers.	507	- Queue all prepare watchers and then call all outstanding watchers.
411	- If we have been forked, recreate the kernel state.	508	- If we have been forked, recreate the kernel state.
412	- Update the kernel state with all outstanding changes.	509	- Update the kernel state with all outstanding changes.
413	- Update the "event loop time".	510	- Update the "event loop time".
414	- Calculate for how long to block.	511	- Calculate for how long to block.
415	- Block the process, waiting for any events.	512	- Block the process, waiting for any events.
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	520	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	521	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	522	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	523	were used, return, otherwise continue with step *.
427		524
428	Example: queue some jobs and then loop until no events are outsanding	525	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	526	anymore.
430		527
431	... queue jobs here, make sure they register event watchers as long	528	... queue jobs here, make sure they register event watchers as long
432	... as they still have work to do (even an idle watcher will do..)	529	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	530	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	550	visible to the libev user and should not keep C<ev_loop> from exiting if
454	no event watchers registered by it are active. It is also an excellent	551	no event watchers registered by it are active. It is also an excellent
455	way to do this for generic recurring timers or from within third-party	552	way to do this for generic recurring timers or from within third-party
456	libraries. Just remember to I<unref after start> and I<ref before stop>.	553	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		554
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	555	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	556	running when nothing else is active.
460		557
461	struct dv_signal exitsig;	558	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	559	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	560	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	561	evf_unref (loop);
465		562
466	Example: for some weird reason, unregister the above signal handler again.	563	Example: For some weird reason, unregister the above signal handler again.
467		564
468	ev_ref (myloop);	565	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	566	ev_signal_stop (loop, &exitsig);
470		567
471	=back	568	=back
472		569
473		570
474	=head1 ANATOMY OF A WATCHER	571	=head1 ANATOMY OF A WATCHER
…		…
544	The signal specified in the C<ev_signal> watcher has been received by a thread.	641	The signal specified in the C<ev_signal> watcher has been received by a thread.
545		642
546	=item C<EV_CHILD>	643	=item C<EV_CHILD>
547		644
548	The pid specified in the C<ev_child> watcher has received a status change.	645	The pid specified in the C<ev_child> watcher has received a status change.
		646
		647	=item C<EV_STAT>
		648
		649	The path specified in the C<ev_stat> watcher changed its attributes somehow.
549		650
550	=item C<EV_IDLE>	651	=item C<EV_IDLE>
551		652
552	The C<ev_idle> watcher has determined that you have nothing better to do.	653	The C<ev_idle> watcher has determined that you have nothing better to do.
553		654
…		…
561	received events. Callbacks of both watcher types can start and stop as	662	received events. Callbacks of both watcher types can start and stop as
562	many watchers as they want, and all of them will be taken into account	663	many watchers as they want, and all of them will be taken into account
563	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	664	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
564	C<ev_loop> from blocking).	665	C<ev_loop> from blocking).
565		666
		667	=item C<EV_EMBED>
		668
		669	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		670
		671	=item C<EV_FORK>
		672
		673	The event loop has been resumed in the child process after fork (see
		674	C<ev_fork>).
		675
566	=item C<EV_ERROR>	676	=item C<EV_ERROR>
567		677
568	An unspecified error has occured, the watcher has been stopped. This might	678	An unspecified error has occured, the watcher has been stopped. This might
569	happen because the watcher could not be properly started because libev	679	happen because the watcher could not be properly started because libev
570	ran out of memory, a file descriptor was found to be closed or any other	680	ran out of memory, a file descriptor was found to be closed or any other
…		…
641	=item bool ev_is_pending (ev_TYPE *watcher)	751	=item bool ev_is_pending (ev_TYPE *watcher)
642		752
643	Returns a true value iff the watcher is pending, (i.e. it has outstanding	753	Returns a true value iff the watcher is pending, (i.e. it has outstanding
644	events but its callback has not yet been invoked). As long as a watcher	754	events but its callback has not yet been invoked). As long as a watcher
645	is pending (but not active) you must not call an init function on it (but	755	is pending (but not active) you must not call an init function on it (but
646	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	756	C<ev_TYPE_set> is safe), you must not change its priority, and you must
647	libev (e.g. you cnanot C<free ()> it).	757	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		758	it).
648		759
649	=item callback = ev_cb (ev_TYPE *watcher)	760	=item callback ev_cb (ev_TYPE *watcher)
650		761
651	Returns the callback currently set on the watcher.	762	Returns the callback currently set on the watcher.
652		763
653	=item ev_cb_set (ev_TYPE *watcher, callback)	764	=item ev_cb_set (ev_TYPE *watcher, callback)
654		765
655	Change the callback. You can change the callback at virtually any time	766	Change the callback. You can change the callback at virtually any time
656	(modulo threads).	767	(modulo threads).
		768
		769	=item ev_set_priority (ev_TYPE *watcher, priority)
		770
		771	=item int ev_priority (ev_TYPE *watcher)
		772
		773	Set and query the priority of the watcher. The priority is a small
		774	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		775	(default: C<-2>). Pending watchers with higher priority will be invoked
		776	before watchers with lower priority, but priority will not keep watchers
		777	from being executed (except for C<ev_idle> watchers).
		778
		779	This means that priorities are I<only> used for ordering callback
		780	invocation after new events have been received. This is useful, for
		781	example, to reduce latency after idling, or more often, to bind two
		782	watchers on the same event and make sure one is called first.
		783
		784	If you need to suppress invocation when higher priority events are pending
		785	you need to look at C<ev_idle> watchers, which provide this functionality.
		786
		787	You I<must not> change the priority of a watcher as long as it is active or
		788	pending.
		789
		790	The default priority used by watchers when no priority has been set is
		791	always C<0>, which is supposed to not be too high and not be too low :).
		792
		793	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		794	fine, as long as you do not mind that the priority value you query might
		795	or might not have been adjusted to be within valid range.
		796
		797	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		798
		799	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		800	C<loop> nor C<revents> need to be valid as long as the watcher callback
		801	can deal with that fact.
		802
		803	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		804
		805	If the watcher is pending, this function returns clears its pending status
		806	and returns its C<revents> bitset (as if its callback was invoked). If the
		807	watcher isn't pending it does nothing and returns C<0>.
657		808
658	=back	809	=back
659		810
660		811
661	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	812	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
682	{	833	{
683	struct my_io *w = (struct my_io *)w_;	834	struct my_io *w = (struct my_io *)w_;
684	...	835	...
685	}	836	}
686		837
687	More interesting and less C-conformant ways of catsing your callback type	838	More interesting and less C-conformant ways of casting your callback type
688	have been omitted....	839	instead have been omitted.
		840
		841	Another common scenario is having some data structure with multiple
		842	watchers:
		843
		844	struct my_biggy
		845	{
		846	int some_data;
		847	ev_timer t1;
		848	ev_timer t2;
		849	}
		850
		851	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		852	you need to use C<offsetof>:
		853
		854	#include <stddef.h>
		855
		856	static void
		857	t1_cb (EV_P_ struct ev_timer *w, int revents)
		858	{
		859	struct my_biggy big = (struct my_biggy *
		860	(((char *)w) - offsetof (struct my_biggy, t1));
		861	}
		862
		863	static void
		864	t2_cb (EV_P_ struct ev_timer *w, int revents)
		865	{
		866	struct my_biggy big = (struct my_biggy *
		867	(((char *)w) - offsetof (struct my_biggy, t2));
		868	}
689		869
690		870
691	=head1 WATCHER TYPES	871	=head1 WATCHER TYPES
692		872
693	This section describes each watcher in detail, but will not repeat	873	This section describes each watcher in detail, but will not repeat
694	information given in the last section.	874	information given in the last section. Any initialisation/set macros,
		875	functions and members specific to the watcher type are explained.
		876
		877	Members are additionally marked with either I<[read-only]>, meaning that,
		878	while the watcher is active, you can look at the member and expect some
		879	sensible content, but you must not modify it (you can modify it while the
		880	watcher is stopped to your hearts content), or I<[read-write]>, which
		881	means you can expect it to have some sensible content while the watcher
		882	is active, but you can also modify it. Modifying it may not do something
		883	sensible or take immediate effect (or do anything at all), but libev will
		884	not crash or malfunction in any way.
695		885
696		886
697	=head2 C<ev_io> - is this file descriptor readable or writable?	887	=head2 C<ev_io> - is this file descriptor readable or writable?
698		888
699	I/O watchers check whether a file descriptor is readable or writable	889	I/O watchers check whether a file descriptor is readable or writable
…		…
728	it is best to always use non-blocking I/O: An extra C<read>(2) returning	918	it is best to always use non-blocking I/O: An extra C<read>(2) returning
729	C<EAGAIN> is far preferable to a program hanging until some data arrives.	919	C<EAGAIN> is far preferable to a program hanging until some data arrives.
730		920
731	If you cannot run the fd in non-blocking mode (for example you should not	921	If you cannot run the fd in non-blocking mode (for example you should not
732	play around with an Xlib connection), then you have to seperately re-test	922	play around with an Xlib connection), then you have to seperately re-test
733	wether a file descriptor is really ready with a known-to-be good interface	923	whether a file descriptor is really ready with a known-to-be good interface
734	such as poll (fortunately in our Xlib example, Xlib already does this on	924	such as poll (fortunately in our Xlib example, Xlib already does this on
735	its own, so its quite safe to use).	925	its own, so its quite safe to use).
		926
		927	=head3 The special problem of disappearing file descriptors
		928
		929	Some backends (e.g kqueue, epoll) need to be told about closing a file
		930	descriptor (either by calling C<close> explicitly or by any other means,
		931	such as C<dup>). The reason is that you register interest in some file
		932	descriptor, but when it goes away, the operating system will silently drop
		933	this interest. If another file descriptor with the same number then is
		934	registered with libev, there is no efficient way to see that this is, in
		935	fact, a different file descriptor.
		936
		937	To avoid having to explicitly tell libev about such cases, libev follows
		938	the following policy: Each time C<ev_io_set> is being called, libev
		939	will assume that this is potentially a new file descriptor, otherwise
		940	it is assumed that the file descriptor stays the same. That means that
		941	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		942	descriptor even if the file descriptor number itself did not change.
		943
		944	This is how one would do it normally anyway, the important point is that
		945	the libev application should not optimise around libev but should leave
		946	optimisations to libev.
		947
		948
		949	=head3 Watcher-Specific Functions
736		950
737	=over 4	951	=over 4
738		952
739	=item ev_io_init (ev_io *, callback, int fd, int events)	953	=item ev_io_init (ev_io *, callback, int fd, int events)
740		954
…		…
742		956
743	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	957	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
744	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	958	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
745	C<EV_READ | EV_WRITE> to receive the given events.	959	C<EV_READ | EV_WRITE> to receive the given events.
746		960
		961	=item int fd [read-only]
		962
		963	The file descriptor being watched.
		964
		965	=item int events [read-only]
		966
		967	The events being watched.
		968
747	=back	969	=back
748		970
749	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	971	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
750	readable, but only once. Since it is likely line-buffered, you could	972	readable, but only once. Since it is likely line-buffered, you could
751	attempt to read a whole line in the callback:	973	attempt to read a whole line in the callback.
752		974
753	static void	975	static void
754	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	976	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
755	{	977	{
756	ev_io_stop (loop, w);	978	ev_io_stop (loop, w);
…		…
786		1008
787	The callback is guarenteed to be invoked only when its timeout has passed,	1009	The callback is guarenteed to be invoked only when its timeout has passed,
788	but if multiple timers become ready during the same loop iteration then	1010	but if multiple timers become ready during the same loop iteration then
789	order of execution is undefined.	1011	order of execution is undefined.
790		1012
		1013	=head3 Watcher-Specific Functions and Data Members
		1014
791	=over 4	1015	=over 4
792		1016
793	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1017	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
794		1018
795	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1019	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
808	=item ev_timer_again (loop)	1032	=item ev_timer_again (loop)
809		1033
810	This will act as if the timer timed out and restart it again if it is	1034	This will act as if the timer timed out and restart it again if it is
811	repeating. The exact semantics are:	1035	repeating. The exact semantics are:
812		1036
		1037	If the timer is pending, its pending status is cleared.
		1038
813	If the timer is started but nonrepeating, stop it.	1039	If the timer is started but nonrepeating, stop it (as if it timed out).
814		1040
815	If the timer is repeating, either start it if necessary (with the repeat	1041	If the timer is repeating, either start it if necessary (with the
816	value), or reset the running timer to the repeat value.	1042	C<repeat> value), or reset the running timer to the C<repeat> value.
817		1043
818	This sounds a bit complicated, but here is a useful and typical	1044	This sounds a bit complicated, but here is a useful and typical
819	example: Imagine you have a tcp connection and you want a so-called idle	1045	example: Imagine you have a tcp connection and you want a so-called idle
820	timeout, that is, you want to be called when there have been, say, 60	1046	timeout, that is, you want to be called when there have been, say, 60
821	seconds of inactivity on the socket. The easiest way to do this is to	1047	seconds of inactivity on the socket. The easiest way to do this is to
822	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each	1048	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
823	time you successfully read or write some data. If you go into an idle	1049	C<ev_timer_again> each time you successfully read or write some data. If
824	state where you do not expect data to travel on the socket, you can stop	1050	you go into an idle state where you do not expect data to travel on the
825	the timer, and again will automatically restart it if need be.	1051	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
		1052	automatically restart it if need be.
		1053
		1054	That means you can ignore the C<after> value and C<ev_timer_start>
		1055	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
		1056
		1057	ev_timer_init (timer, callback, 0., 5.);
		1058	ev_timer_again (loop, timer);
		1059	...
		1060	timer->again = 17.;
		1061	ev_timer_again (loop, timer);
		1062	...
		1063	timer->again = 10.;
		1064	ev_timer_again (loop, timer);
		1065
		1066	This is more slightly efficient then stopping/starting the timer each time
		1067	you want to modify its timeout value.
		1068
		1069	=item ev_tstamp repeat [read-write]
		1070
		1071	The current C<repeat> value. Will be used each time the watcher times out
		1072	or C<ev_timer_again> is called and determines the next timeout (if any),
		1073	which is also when any modifications are taken into account.
826		1074
827	=back	1075	=back
828		1076
829	Example: create a timer that fires after 60 seconds.	1077	Example: Create a timer that fires after 60 seconds.
830		1078
831	static void	1079	static void
832	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1080	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
833	{	1081	{
834	.. one minute over, w is actually stopped right here	1082	.. one minute over, w is actually stopped right here
…		…
836		1084
837	struct ev_timer mytimer;	1085	struct ev_timer mytimer;
838	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1086	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
839	ev_timer_start (loop, &mytimer);	1087	ev_timer_start (loop, &mytimer);
840		1088
841	Example: create a timeout timer that times out after 10 seconds of	1089	Example: Create a timeout timer that times out after 10 seconds of
842	inactivity.	1090	inactivity.
843		1091
844	static void	1092	static void
845	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1093	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
846	{	1094	{
…		…
866	but on wallclock time (absolute time). You can tell a periodic watcher	1114	but on wallclock time (absolute time). You can tell a periodic watcher
867	to trigger "at" some specific point in time. For example, if you tell a	1115	to trigger "at" some specific point in time. For example, if you tell a
868	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1116	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
869	+ 10.>) and then reset your system clock to the last year, then it will	1117	+ 10.>) and then reset your system clock to the last year, then it will
870	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1118	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
871	roughly 10 seconds later and of course not if you reset your system time	1119	roughly 10 seconds later).
872	again).
873		1120
874	They can also be used to implement vastly more complex timers, such as	1121	They can also be used to implement vastly more complex timers, such as
875	triggering an event on eahc midnight, local time.	1122	triggering an event on each midnight, local time or other, complicated,
		1123	rules.
876		1124
877	As with timers, the callback is guarenteed to be invoked only when the	1125	As with timers, the callback is guarenteed to be invoked only when the
878	time (C<at>) has been passed, but if multiple periodic timers become ready	1126	time (C<at>) has been passed, but if multiple periodic timers become ready
879	during the same loop iteration then order of execution is undefined.	1127	during the same loop iteration then order of execution is undefined.
880		1128
		1129	=head3 Watcher-Specific Functions and Data Members
		1130
881	=over 4	1131	=over 4
882		1132
883	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1133	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
884		1134
885	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1135	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
887	Lots of arguments, lets sort it out... There are basically three modes of	1137	Lots of arguments, lets sort it out... There are basically three modes of
888	operation, and we will explain them from simplest to complex:	1138	operation, and we will explain them from simplest to complex:
889		1139
890	=over 4	1140	=over 4
891		1141
892	=item * absolute timer (interval = reschedule_cb = 0)	1142	=item * absolute timer (at = time, interval = reschedule_cb = 0)
893		1143
894	In this configuration the watcher triggers an event at the wallclock time	1144	In this configuration the watcher triggers an event at the wallclock time
895	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1145	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
896	that is, if it is to be run at January 1st 2011 then it will run when the	1146	that is, if it is to be run at January 1st 2011 then it will run when the
897	system time reaches or surpasses this time.	1147	system time reaches or surpasses this time.
898		1148
899	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1149	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
900		1150
901	In this mode the watcher will always be scheduled to time out at the next	1151	In this mode the watcher will always be scheduled to time out at the next
902	C<at + N * interval> time (for some integer N) and then repeat, regardless	1152	C<at + N * interval> time (for some integer N, which can also be negative)
903	of any time jumps.	1153	and then repeat, regardless of any time jumps.
904		1154
905	This can be used to create timers that do not drift with respect to system	1155	This can be used to create timers that do not drift with respect to system
906	time:	1156	time:
907		1157
908	ev_periodic_set (&periodic, 0., 3600., 0);	1158	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
914		1164
915	Another way to think about it (for the mathematically inclined) is that	1165	Another way to think about it (for the mathematically inclined) is that
916	C<ev_periodic> will try to run the callback in this mode at the next possible	1166	C<ev_periodic> will try to run the callback in this mode at the next possible
917	time where C<time = at (mod interval)>, regardless of any time jumps.	1167	time where C<time = at (mod interval)>, regardless of any time jumps.
918		1168
		1169	For numerical stability it is preferable that the C<at> value is near
		1170	C<ev_now ()> (the current time), but there is no range requirement for
		1171	this value.
		1172
919	=item * manual reschedule mode (reschedule_cb = callback)	1173	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
920		1174
921	In this mode the values for C<interval> and C<at> are both being	1175	In this mode the values for C<interval> and C<at> are both being
922	ignored. Instead, each time the periodic watcher gets scheduled, the	1176	ignored. Instead, each time the periodic watcher gets scheduled, the
923	reschedule callback will be called with the watcher as first, and the	1177	reschedule callback will be called with the watcher as first, and the
924	current time as second argument.	1178	current time as second argument.
925		1179
926	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1180	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
927	ever, or make any event loop modifications>. If you need to stop it,	1181	ever, or make any event loop modifications>. If you need to stop it,
928	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1182	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
929	starting a prepare watcher).	1183	starting an C<ev_prepare> watcher, which is legal).
930		1184
931	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1185	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
932	ev_tstamp now)>, e.g.:	1186	ev_tstamp now)>, e.g.:
933		1187
934	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1188	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
957	Simply stops and restarts the periodic watcher again. This is only useful	1211	Simply stops and restarts the periodic watcher again. This is only useful
958	when you changed some parameters or the reschedule callback would return	1212	when you changed some parameters or the reschedule callback would return
959	a different time than the last time it was called (e.g. in a crond like	1213	a different time than the last time it was called (e.g. in a crond like
960	program when the crontabs have changed).	1214	program when the crontabs have changed).
961		1215
		1216	=item ev_tstamp offset [read-write]
		1217
		1218	When repeating, this contains the offset value, otherwise this is the
		1219	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1220
		1221	Can be modified any time, but changes only take effect when the periodic
		1222	timer fires or C<ev_periodic_again> is being called.
		1223
		1224	=item ev_tstamp interval [read-write]
		1225
		1226	The current interval value. Can be modified any time, but changes only
		1227	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1228	called.
		1229
		1230	=item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]
		1231
		1232	The current reschedule callback, or C<0>, if this functionality is
		1233	switched off. Can be changed any time, but changes only take effect when
		1234	the periodic timer fires or C<ev_periodic_again> is being called.
		1235
		1236	=item ev_tstamp at [read-only]
		1237
		1238	When active, contains the absolute time that the watcher is supposed to
		1239	trigger next.
		1240
962	=back	1241	=back
963		1242
964	Example: call a callback every hour, or, more precisely, whenever the	1243	Example: Call a callback every hour, or, more precisely, whenever the
965	system clock is divisible by 3600. The callback invocation times have	1244	system clock is divisible by 3600. The callback invocation times have
966	potentially a lot of jittering, but good long-term stability.	1245	potentially a lot of jittering, but good long-term stability.
967		1246
968	static void	1247	static void
969	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1248	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
…		…
973		1252
974	struct ev_periodic hourly_tick;	1253	struct ev_periodic hourly_tick;
975	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1254	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
976	ev_periodic_start (loop, &hourly_tick);	1255	ev_periodic_start (loop, &hourly_tick);
977		1256
978	Example: the same as above, but use a reschedule callback to do it:	1257	Example: The same as above, but use a reschedule callback to do it:
979		1258
980	#include <math.h>	1259	#include <math.h>
981		1260
982	static ev_tstamp	1261	static ev_tstamp
983	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1262	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
985	return fmod (now, 3600.) + 3600.;	1264	return fmod (now, 3600.) + 3600.;
986	}	1265	}
987		1266
988	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1267	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
989		1268
990	Example: call a callback every hour, starting now:	1269	Example: Call a callback every hour, starting now:
991		1270
992	struct ev_periodic hourly_tick;	1271	struct ev_periodic hourly_tick;
993	ev_periodic_init (&hourly_tick, clock_cb,	1272	ev_periodic_init (&hourly_tick, clock_cb,
994	fmod (ev_now (loop), 3600.), 3600., 0);	1273	fmod (ev_now (loop), 3600.), 3600., 0);
995	ev_periodic_start (loop, &hourly_tick);	1274	ev_periodic_start (loop, &hourly_tick);
…		…
1007	with the kernel (thus it coexists with your own signal handlers as long	1286	with the kernel (thus it coexists with your own signal handlers as long
1008	as you don't register any with libev). Similarly, when the last signal	1287	as you don't register any with libev). Similarly, when the last signal
1009	watcher for a signal is stopped libev will reset the signal handler to	1288	watcher for a signal is stopped libev will reset the signal handler to
1010	SIG_DFL (regardless of what it was set to before).	1289	SIG_DFL (regardless of what it was set to before).
1011		1290
		1291	=head3 Watcher-Specific Functions and Data Members
		1292
1012	=over 4	1293	=over 4
1013		1294
1014	=item ev_signal_init (ev_signal *, callback, int signum)	1295	=item ev_signal_init (ev_signal *, callback, int signum)
1015		1296
1016	=item ev_signal_set (ev_signal *, int signum)	1297	=item ev_signal_set (ev_signal *, int signum)
1017		1298
1018	Configures the watcher to trigger on the given signal number (usually one	1299	Configures the watcher to trigger on the given signal number (usually one
1019	of the C<SIGxxx> constants).	1300	of the C<SIGxxx> constants).
1020		1301
		1302	=item int signum [read-only]
		1303
		1304	The signal the watcher watches out for.
		1305
1021	=back	1306	=back
1022		1307
1023		1308
1024	=head2 C<ev_child> - watch out for process status changes	1309	=head2 C<ev_child> - watch out for process status changes
1025		1310
1026	Child watchers trigger when your process receives a SIGCHLD in response to	1311	Child watchers trigger when your process receives a SIGCHLD in response to
1027	some child status changes (most typically when a child of yours dies).	1312	some child status changes (most typically when a child of yours dies).
		1313
		1314	=head3 Watcher-Specific Functions and Data Members
1028		1315
1029	=over 4	1316	=over 4
1030		1317
1031	=item ev_child_init (ev_child *, callback, int pid)	1318	=item ev_child_init (ev_child *, callback, int pid)
1032		1319
…		…
1037	at the C<rstatus> member of the C<ev_child> watcher structure to see	1324	at the C<rstatus> member of the C<ev_child> watcher structure to see
1038	the status word (use the macros from C<sys/wait.h> and see your systems	1325	the status word (use the macros from C<sys/wait.h> and see your systems
1039	C<waitpid> documentation). The C<rpid> member contains the pid of the	1326	C<waitpid> documentation). The C<rpid> member contains the pid of the
1040	process causing the status change.	1327	process causing the status change.
1041		1328
		1329	=item int pid [read-only]
		1330
		1331	The process id this watcher watches out for, or C<0>, meaning any process id.
		1332
		1333	=item int rpid [read-write]
		1334
		1335	The process id that detected a status change.
		1336
		1337	=item int rstatus [read-write]
		1338
		1339	The process exit/trace status caused by C<rpid> (see your systems
		1340	C<waitpid> and C<sys/wait.h> documentation for details).
		1341
1042	=back	1342	=back
1043		1343
1044	Example: try to exit cleanly on SIGINT and SIGTERM.	1344	Example: Try to exit cleanly on SIGINT and SIGTERM.
1045		1345
1046	static void	1346	static void
1047	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1347	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1048	{	1348	{
1049	ev_unloop (loop, EVUNLOOP_ALL);	1349	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1052	struct ev_signal signal_watcher;	1352	struct ev_signal signal_watcher;
1053	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1353	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1054	ev_signal_start (loop, &sigint_cb);	1354	ev_signal_start (loop, &sigint_cb);
1055		1355
1056		1356
		1357	=head2 C<ev_stat> - did the file attributes just change?
		1358
		1359	This watches a filesystem path for attribute changes. That is, it calls
		1360	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1361	compared to the last time, invoking the callback if it did.
		1362
		1363	The path does not need to exist: changing from "path exists" to "path does
		1364	not exist" is a status change like any other. The condition "path does
		1365	not exist" is signified by the C<st_nlink> field being zero (which is
		1366	otherwise always forced to be at least one) and all the other fields of
		1367	the stat buffer having unspecified contents.
		1368
		1369	The path I<should> be absolute and I<must not> end in a slash. If it is
		1370	relative and your working directory changes, the behaviour is undefined.
		1371
		1372	Since there is no standard to do this, the portable implementation simply
		1373	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1374	can specify a recommended polling interval for this case. If you specify
		1375	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1376	unspecified default> value will be used (which you can expect to be around
		1377	five seconds, although this might change dynamically). Libev will also
		1378	impose a minimum interval which is currently around C<0.1>, but thats
		1379	usually overkill.
		1380
		1381	This watcher type is not meant for massive numbers of stat watchers,
		1382	as even with OS-supported change notifications, this can be
		1383	resource-intensive.
		1384
		1385	At the time of this writing, only the Linux inotify interface is
		1386	implemented (implementing kqueue support is left as an exercise for the
		1387	reader). Inotify will be used to give hints only and should not change the
		1388	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1389	to fall back to regular polling again even with inotify, but changes are
		1390	usually detected immediately, and if the file exists there will be no
		1391	polling.
		1392
		1393	=head3 Watcher-Specific Functions and Data Members
		1394
		1395	=over 4
		1396
		1397	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
		1398
		1399	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)
		1400
		1401	Configures the watcher to wait for status changes of the given
		1402	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1403	be detected and should normally be specified as C<0> to let libev choose
		1404	a suitable value. The memory pointed to by C<path> must point to the same
		1405	path for as long as the watcher is active.
		1406
		1407	The callback will be receive C<EV_STAT> when a change was detected,
		1408	relative to the attributes at the time the watcher was started (or the
		1409	last change was detected).
		1410
		1411	=item ev_stat_stat (ev_stat *)
		1412
		1413	Updates the stat buffer immediately with new values. If you change the
		1414	watched path in your callback, you could call this fucntion to avoid
		1415	detecting this change (while introducing a race condition). Can also be
		1416	useful simply to find out the new values.
		1417
		1418	=item ev_statdata attr [read-only]
		1419
		1420	The most-recently detected attributes of the file. Although the type is of
		1421	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1422	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1423	was some error while C<stat>ing the file.
		1424
		1425	=item ev_statdata prev [read-only]
		1426
		1427	The previous attributes of the file. The callback gets invoked whenever
		1428	C<prev> != C<attr>.
		1429
		1430	=item ev_tstamp interval [read-only]
		1431
		1432	The specified interval.
		1433
		1434	=item const char *path [read-only]
		1435
		1436	The filesystem path that is being watched.
		1437
		1438	=back
		1439
		1440	Example: Watch C</etc/passwd> for attribute changes.
		1441
		1442	static void
		1443	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
		1444	{
		1445	/* /etc/passwd changed in some way */
		1446	if (w->attr.st_nlink)
		1447	{
		1448	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1449	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1450	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1451	}
		1452	else
		1453	/* you shalt not abuse printf for puts */
		1454	puts ("wow, /etc/passwd is not there, expect problems. "
		1455	"if this is windows, they already arrived\n");
		1456	}
		1457
		1458	...
		1459	ev_stat passwd;
		1460
		1461	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1462	ev_stat_start (loop, &passwd);
		1463
		1464
1057	=head2 C<ev_idle> - when you've got nothing better to do...	1465	=head2 C<ev_idle> - when you've got nothing better to do...
1058		1466
1059	Idle watchers trigger events when there are no other events are pending	1467	Idle watchers trigger events when no other events of the same or higher
1060	(prepare, check and other idle watchers do not count). That is, as long	1468	priority are pending (prepare, check and other idle watchers do not
1061	as your process is busy handling sockets or timeouts (or even signals,	1469	count).
1062	imagine) it will not be triggered. But when your process is idle all idle	1470
1063	watchers are being called again and again, once per event loop iteration -	1471	That is, as long as your process is busy handling sockets or timeouts
		1472	(or even signals, imagine) of the same or higher priority it will not be
		1473	triggered. But when your process is idle (or only lower-priority watchers
		1474	are pending), the idle watchers are being called once per event loop
1064	until stopped, that is, or your process receives more events and becomes	1475	iteration - until stopped, that is, or your process receives more events
1065	busy.	1476	and becomes busy again with higher priority stuff.
1066		1477
1067	The most noteworthy effect is that as long as any idle watchers are	1478	The most noteworthy effect is that as long as any idle watchers are
1068	active, the process will not block when waiting for new events.	1479	active, the process will not block when waiting for new events.
1069		1480
1070	Apart from keeping your process non-blocking (which is a useful	1481	Apart from keeping your process non-blocking (which is a useful
1071	effect on its own sometimes), idle watchers are a good place to do	1482	effect on its own sometimes), idle watchers are a good place to do
1072	"pseudo-background processing", or delay processing stuff to after the	1483	"pseudo-background processing", or delay processing stuff to after the
1073	event loop has handled all outstanding events.	1484	event loop has handled all outstanding events.
1074		1485
		1486	=head3 Watcher-Specific Functions and Data Members
		1487
1075	=over 4	1488	=over 4
1076		1489
1077	=item ev_idle_init (ev_signal *, callback)	1490	=item ev_idle_init (ev_signal *, callback)
1078		1491
1079	Initialises and configures the idle watcher - it has no parameters of any	1492	Initialises and configures the idle watcher - it has no parameters of any
1080	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1493	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1081	believe me.	1494	believe me.
1082		1495
1083	=back	1496	=back
1084		1497
1085	Example: dynamically allocate an C<ev_idle>, start it, and in the	1498	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1086	callback, free it. Alos, use no error checking, as usual.	1499	callback, free it. Also, use no error checking, as usual.
1087		1500
1088	static void	1501	static void
1089	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1502	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1090	{	1503	{
1091	free (w);	1504	free (w);
…		…
1136	with priority higher than or equal to the event loop and one coroutine	1549	with priority higher than or equal to the event loop and one coroutine
1137	of lower priority, but only once, using idle watchers to keep the event	1550	of lower priority, but only once, using idle watchers to keep the event
1138	loop from blocking if lower-priority coroutines are active, thus mapping	1551	loop from blocking if lower-priority coroutines are active, thus mapping
1139	low-priority coroutines to idle/background tasks).	1552	low-priority coroutines to idle/background tasks).
1140		1553
		1554	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1555	priority, to ensure that they are being run before any other watchers
		1556	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1557	too) should not activate ("feed") events into libev. While libev fully
		1558	supports this, they will be called before other C<ev_check> watchers did
		1559	their job. As C<ev_check> watchers are often used to embed other event
		1560	loops those other event loops might be in an unusable state until their
		1561	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1562	others).
		1563
		1564	=head3 Watcher-Specific Functions and Data Members
		1565
1141	=over 4	1566	=over 4
1142		1567
1143	=item ev_prepare_init (ev_prepare *, callback)	1568	=item ev_prepare_init (ev_prepare *, callback)
1144		1569
1145	=item ev_check_init (ev_check *, callback)	1570	=item ev_check_init (ev_check *, callback)
…		…
1148	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1573	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1149	macros, but using them is utterly, utterly and completely pointless.	1574	macros, but using them is utterly, utterly and completely pointless.
1150		1575
1151	=back	1576	=back
1152		1577
1153	Example: To include a library such as adns, you would add IO watchers	1578	There are a number of principal ways to embed other event loops or modules
1154	and a timeout watcher in a prepare handler, as required by libadns, and	1579	into libev. Here are some ideas on how to include libadns into libev
		1580	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1581	use for an actually working example. Another Perl module named C<EV::Glib>
		1582	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1583	into the Glib event loop).
		1584
		1585	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1155	in a check watcher, destroy them and call into libadns. What follows is	1586	and in a check watcher, destroy them and call into libadns. What follows
1156	pseudo-code only of course:	1587	is pseudo-code only of course. This requires you to either use a low
		1588	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1589	the callbacks for the IO/timeout watchers might not have been called yet.
1157		1590
1158	static ev_io iow [nfd];	1591	static ev_io iow [nfd];
1159	static ev_timer tw;	1592	static ev_timer tw;
1160		1593
1161	static void	1594	static void
1162	io_cb (ev_loop *loop, ev_io *w, int revents)	1595	io_cb (ev_loop *loop, ev_io *w, int revents)
1163	{	1596	{
1164	// set the relevant poll flags
1165	// could also call adns_processreadable etc. here
1166	struct pollfd *fd = (struct pollfd *)w->data;
1167	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1168	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1169	}	1597	}
1170		1598
1171	// create io watchers for each fd and a timer before blocking	1599	// create io watchers for each fd and a timer before blocking
1172	static void	1600	static void
1173	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1601	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1174	{	1602	{
1175	int timeout = 3600000;truct pollfd fds [nfd];	1603	int timeout = 3600000;
		1604	struct pollfd fds [nfd];
1176	// actual code will need to loop here and realloc etc.	1605	// actual code will need to loop here and realloc etc.
1177	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1606	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1178		1607
1179	/* the callback is illegal, but won't be called as we stop during check */	1608	/* the callback is illegal, but won't be called as we stop during check */
1180	ev_timer_init (&tw, 0, timeout * 1e-3);	1609	ev_timer_init (&tw, 0, timeout * 1e-3);
1181	ev_timer_start (loop, &tw);	1610	ev_timer_start (loop, &tw);
1182		1611
1183	// create on ev_io per pollfd	1612	// create one ev_io per pollfd
1184	for (int i = 0; i < nfd; ++i)	1613	for (int i = 0; i < nfd; ++i)
1185	{	1614	{
1186	ev_io_init (iow + i, io_cb, fds [i].fd,	1615	ev_io_init (iow + i, io_cb, fds [i].fd,
1187	((fds [i].events & POLLIN ? EV_READ : 0)	1616	((fds [i].events & POLLIN ? EV_READ : 0)
1188	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1617	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1189		1618
1190	fds [i].revents = 0;	1619	fds [i].revents = 0;
1191	iow [i].data = fds + i;
1192	ev_io_start (loop, iow + i);	1620	ev_io_start (loop, iow + i);
1193	}	1621	}
1194	}	1622	}
1195		1623
1196	// stop all watchers after blocking	1624	// stop all watchers after blocking
…		…
1198	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1626	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1199	{	1627	{
1200	ev_timer_stop (loop, &tw);	1628	ev_timer_stop (loop, &tw);
1201		1629
1202	for (int i = 0; i < nfd; ++i)	1630	for (int i = 0; i < nfd; ++i)
		1631	{
		1632	// set the relevant poll flags
		1633	// could also call adns_processreadable etc. here
		1634	struct pollfd *fd = fds + i;
		1635	int revents = ev_clear_pending (iow + i);
		1636	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1637	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1638
		1639	// now stop the watcher
1203	ev_io_stop (loop, iow + i);	1640	ev_io_stop (loop, iow + i);
		1641	}
1204		1642
1205	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1643	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1644	}
		1645
		1646	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1647	in the prepare watcher and would dispose of the check watcher.
		1648
		1649	Method 3: If the module to be embedded supports explicit event
		1650	notification (adns does), you can also make use of the actual watcher
		1651	callbacks, and only destroy/create the watchers in the prepare watcher.
		1652
		1653	static void
		1654	timer_cb (EV_P_ ev_timer *w, int revents)
		1655	{
		1656	adns_state ads = (adns_state)w->data;
		1657	update_now (EV_A);
		1658
		1659	adns_processtimeouts (ads, &tv_now);
		1660	}
		1661
		1662	static void
		1663	io_cb (EV_P_ ev_io *w, int revents)
		1664	{
		1665	adns_state ads = (adns_state)w->data;
		1666	update_now (EV_A);
		1667
		1668	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1669	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1670	}
		1671
		1672	// do not ever call adns_afterpoll
		1673
		1674	Method 4: Do not use a prepare or check watcher because the module you
		1675	want to embed is too inflexible to support it. Instead, youc na override
		1676	their poll function. The drawback with this solution is that the main
		1677	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1678	this.
		1679
		1680	static gint
		1681	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1682	{
		1683	int got_events = 0;
		1684
		1685	for (n = 0; n < nfds; ++n)
		1686	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1687
		1688	if (timeout >= 0)
		1689	// create/start timer
		1690
		1691	// poll
		1692	ev_loop (EV_A_ 0);
		1693
		1694	// stop timer again
		1695	if (timeout >= 0)
		1696	ev_timer_stop (EV_A_ &to);
		1697
		1698	// stop io watchers again - their callbacks should have set
		1699	for (n = 0; n < nfds; ++n)
		1700	ev_io_stop (EV_A_ iow [n]);
		1701
		1702	return got_events;
1206	}	1703	}
1207		1704
1208		1705
1209	=head2 C<ev_embed> - when one backend isn't enough...	1706	=head2 C<ev_embed> - when one backend isn't enough...
1210		1707
…		…
1274	ev_embed_start (loop_hi, &embed);	1771	ev_embed_start (loop_hi, &embed);
1275	}	1772	}
1276	else	1773	else
1277	loop_lo = loop_hi;	1774	loop_lo = loop_hi;
1278		1775
		1776	=head3 Watcher-Specific Functions and Data Members
		1777
1279	=over 4	1778	=over 4
1280		1779
1281	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)	1780	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
1282		1781
1283	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	1782	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)
…		…
1292		1791
1293	Make a single, non-blocking sweep over the embedded loop. This works	1792	Make a single, non-blocking sweep over the embedded loop. This works
1294	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1793	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1295	apropriate way for embedded loops.	1794	apropriate way for embedded loops.
1296		1795
		1796	=item struct ev_loop *other [read-only]
		1797
		1798	The embedded event loop.
		1799
		1800	=back
		1801
		1802
		1803	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1804
		1805	Fork watchers are called when a C<fork ()> was detected (usually because
		1806	whoever is a good citizen cared to tell libev about it by calling
		1807	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1808	event loop blocks next and before C<ev_check> watchers are being called,
		1809	and only in the child after the fork. If whoever good citizen calling
		1810	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1811	handlers will be invoked, too, of course.
		1812
		1813	=head3 Watcher-Specific Functions and Data Members
		1814
		1815	=over 4
		1816
		1817	=item ev_fork_init (ev_signal *, callback)
		1818
		1819	Initialises and configures the fork watcher - it has no parameters of any
		1820	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1821	believe me.
		1822
1297	=back	1823	=back
1298		1824
1299		1825
1300	=head1 OTHER FUNCTIONS	1826	=head1 OTHER FUNCTIONS
1301		1827
…		…
1389		1915
1390	To use it,	1916	To use it,
1391		1917
1392	#include <ev++.h>	1918	#include <ev++.h>
1393		1919
1394	(it is not installed by default). This automatically includes F<ev.h>	1920	This automatically includes F<ev.h> and puts all of its definitions (many
1395	and puts all of its definitions (many of them macros) into the global	1921	of them macros) into the global namespace. All C++ specific things are
1396	namespace. All C++ specific things are put into the C<ev> namespace.	1922	put into the C<ev> namespace. It should support all the same embedding
		1923	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1397		1924
1398	It should support all the same embedding options as F<ev.h>, most notably	1925	Care has been taken to keep the overhead low. The only data member the C++
1399	C<EV_MULTIPLICITY>.	1926	classes add (compared to plain C-style watchers) is the event loop pointer
		1927	that the watcher is associated with (or no additional members at all if
		1928	you disable C<EV_MULTIPLICITY> when embedding libev).
		1929
		1930	Currently, functions, and static and non-static member functions can be
		1931	used as callbacks. Other types should be easy to add as long as they only
		1932	need one additional pointer for context. If you need support for other
		1933	types of functors please contact the author (preferably after implementing
		1934	it).
1400		1935
1401	Here is a list of things available in the C<ev> namespace:	1936	Here is a list of things available in the C<ev> namespace:
1402		1937
1403	=over 4	1938	=over 4
1404		1939
…		…
1420		1955
1421	All of those classes have these methods:	1956	All of those classes have these methods:
1422		1957
1423	=over 4	1958	=over 4
1424		1959
1425	=item ev::TYPE::TYPE (object *, object::method *)	1960	=item ev::TYPE::TYPE ()
1426		1961
1427	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)	1962	=item ev::TYPE::TYPE (struct ev_loop *)
1428		1963
1429	=item ev::TYPE::~TYPE	1964	=item ev::TYPE::~TYPE
1430		1965
1431	The constructor takes a pointer to an object and a method pointer to	1966	The constructor (optionally) takes an event loop to associate the watcher
1432	the event handler callback to call in this class. The constructor calls	1967	with. If it is omitted, it will use C<EV_DEFAULT>.
1433	C<ev_init> for you, which means you have to call the C<set> method	1968
1434	before starting it. If you do not specify a loop then the constructor	1969	The constructor calls C<ev_init> for you, which means you have to call the
1435	automatically associates the default loop with this watcher.	1970	C<set> method before starting it.
		1971
		1972	It will not set a callback, however: You have to call the templated C<set>
		1973	method to set a callback before you can start the watcher.
		1974
		1975	(The reason why you have to use a method is a limitation in C++ which does
		1976	not allow explicit template arguments for constructors).
1436		1977
1437	The destructor automatically stops the watcher if it is active.	1978	The destructor automatically stops the watcher if it is active.
		1979
		1980	=item w->set<class, &class::method> (object *)
		1981
		1982	This method sets the callback method to call. The method has to have a
		1983	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1984	first argument and the C<revents> as second. The object must be given as
		1985	parameter and is stored in the C<data> member of the watcher.
		1986
		1987	This method synthesizes efficient thunking code to call your method from
		1988	the C callback that libev requires. If your compiler can inline your
		1989	callback (i.e. it is visible to it at the place of the C<set> call and
		1990	your compiler is good :), then the method will be fully inlined into the
		1991	thunking function, making it as fast as a direct C callback.
		1992
		1993	Example: simple class declaration and watcher initialisation
		1994
		1995	struct myclass
		1996	{
		1997	void io_cb (ev::io &w, int revents) { }
		1998	}
		1999
		2000	myclass obj;
		2001	ev::io iow;
		2002	iow.set <myclass, &myclass::io_cb> (&obj);
		2003
		2004	=item w->set<function> (void *data = 0)
		2005
		2006	Also sets a callback, but uses a static method or plain function as
		2007	callback. The optional C<data> argument will be stored in the watcher's
		2008	C<data> member and is free for you to use.
		2009
		2010	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2011
		2012	See the method-C<set> above for more details.
		2013
		2014	Example:
		2015
		2016	static void io_cb (ev::io &w, int revents) { }
		2017	iow.set <io_cb> ();
1438		2018
1439	=item w->set (struct ev_loop *)	2019	=item w->set (struct ev_loop *)
1440		2020
1441	Associates a different C<struct ev_loop> with this watcher. You can only	2021	Associates a different C<struct ev_loop> with this watcher. You can only
1442	do this when the watcher is inactive (and not pending either).	2022	do this when the watcher is inactive (and not pending either).
1443		2023
1444	=item w->set ([args])	2024	=item w->set ([args])
1445		2025
1446	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2026	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1447	called at least once. Unlike the C counterpart, an active watcher gets	2027	called at least once. Unlike the C counterpart, an active watcher gets
1448	automatically stopped and restarted.	2028	automatically stopped and restarted when reconfiguring it with this
		2029	method.
1449		2030
1450	=item w->start ()	2031	=item w->start ()
1451		2032
1452	Starts the watcher. Note that there is no C<loop> argument as the	2033	Starts the watcher. Note that there is no C<loop> argument, as the
1453	constructor already takes the loop.	2034	constructor already stores the event loop.
1454		2035
1455	=item w->stop ()	2036	=item w->stop ()
1456		2037
1457	Stops the watcher if it is active. Again, no C<loop> argument.	2038	Stops the watcher if it is active. Again, no C<loop> argument.
1458		2039
1459	=item w->again () C<ev::timer>, C<ev::periodic> only	2040	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1460		2041
1461	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2042	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1462	C<ev_TYPE_again> function.	2043	C<ev_TYPE_again> function.
1463		2044
1464	=item w->sweep () C<ev::embed> only	2045	=item w->sweep () (C<ev::embed> only)
1465		2046
1466	Invokes C<ev_embed_sweep>.	2047	Invokes C<ev_embed_sweep>.
		2048
		2049	=item w->update () (C<ev::stat> only)
		2050
		2051	Invokes C<ev_stat_stat>.
1467		2052
1468	=back	2053	=back
1469		2054
1470	=back	2055	=back
1471		2056
…		…
1479		2064
1480	myclass ();	2065	myclass ();
1481	}	2066	}
1482		2067
1483	myclass::myclass (int fd)	2068	myclass::myclass (int fd)
1484	: io (this, &myclass::io_cb),
1485	idle (this, &myclass::idle_cb)
1486	{	2069	{
		2070	io .set <myclass, &myclass::io_cb > (this);
		2071	idle.set <myclass, &myclass::idle_cb> (this);
		2072
1487	io.start (fd, ev::READ);	2073	io.start (fd, ev::READ);
1488	}	2074	}
		2075
		2076
		2077	=head1 MACRO MAGIC
		2078
		2079	Libev can be compiled with a variety of options, the most fundamantal
		2080	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
		2081	functions and callbacks have an initial C<struct ev_loop *> argument.
		2082
		2083	To make it easier to write programs that cope with either variant, the
		2084	following macros are defined:
		2085
		2086	=over 4
		2087
		2088	=item C<EV_A>, C<EV_A_>
		2089
		2090	This provides the loop I<argument> for functions, if one is required ("ev
		2091	loop argument"). The C<EV_A> form is used when this is the sole argument,
		2092	C<EV_A_> is used when other arguments are following. Example:
		2093
		2094	ev_unref (EV_A);
		2095	ev_timer_add (EV_A_ watcher);
		2096	ev_loop (EV_A_ 0);
		2097
		2098	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		2099	which is often provided by the following macro.
		2100
		2101	=item C<EV_P>, C<EV_P_>
		2102
		2103	This provides the loop I<parameter> for functions, if one is required ("ev
		2104	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		2105	C<EV_P_> is used when other parameters are following. Example:
		2106
		2107	// this is how ev_unref is being declared
		2108	static void ev_unref (EV_P);
		2109
		2110	// this is how you can declare your typical callback
		2111	static void cb (EV_P_ ev_timer *w, int revents)
		2112
		2113	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		2114	suitable for use with C<EV_A>.
		2115
		2116	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		2117
		2118	Similar to the other two macros, this gives you the value of the default
		2119	loop, if multiple loops are supported ("ev loop default").
		2120
		2121	=back
		2122
		2123	Example: Declare and initialise a check watcher, utilising the above
		2124	macros so it will work regardless of whether multiple loops are supported
		2125	or not.
		2126
		2127	static void
		2128	check_cb (EV_P_ ev_timer *w, int revents)
		2129	{
		2130	ev_check_stop (EV_A_ w);
		2131	}
		2132
		2133	ev_check check;
		2134	ev_check_init (&check, check_cb);
		2135	ev_check_start (EV_DEFAULT_ &check);
		2136	ev_loop (EV_DEFAULT_ 0);
1489		2137
1490	=head1 EMBEDDING	2138	=head1 EMBEDDING
1491		2139
1492	Libev can (and often is) directly embedded into host	2140	Libev can (and often is) directly embedded into host
1493	applications. Examples of applications that embed it include the Deliantra	2141	applications. Examples of applications that embed it include the Deliantra
1494	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2142	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1495	and rxvt-unicode.	2143	and rxvt-unicode.
1496		2144
1497	The goal is to enable you to just copy the neecssary files into your	2145	The goal is to enable you to just copy the necessary files into your
1498	source directory without having to change even a single line in them, so	2146	source directory without having to change even a single line in them, so
1499	you can easily upgrade by simply copying (or having a checked-out copy of	2147	you can easily upgrade by simply copying (or having a checked-out copy of
1500	libev somewhere in your source tree).	2148	libev somewhere in your source tree).
1501		2149
1502	=head2 FILESETS	2150	=head2 FILESETS
…		…
1533	ev_vars.h	2181	ev_vars.h
1534	ev_wrap.h	2182	ev_wrap.h
1535		2183
1536	ev_win32.c required on win32 platforms only	2184	ev_win32.c required on win32 platforms only
1537		2185
1538	ev_select.c only when select backend is enabled (which is by default)	2186	ev_select.c only when select backend is enabled (which is enabled by default)
1539	ev_poll.c only when poll backend is enabled (disabled by default)	2187	ev_poll.c only when poll backend is enabled (disabled by default)
1540	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2188	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1541	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2189	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1542	ev_port.c only when the solaris port backend is enabled (disabled by default)	2190	ev_port.c only when the solaris port backend is enabled (disabled by default)
1543		2191
…		…
1592		2240
1593	If defined to be C<1>, libev will try to detect the availability of the	2241	If defined to be C<1>, libev will try to detect the availability of the
1594	monotonic clock option at both compiletime and runtime. Otherwise no use	2242	monotonic clock option at both compiletime and runtime. Otherwise no use
1595	of the monotonic clock option will be attempted. If you enable this, you	2243	of the monotonic clock option will be attempted. If you enable this, you
1596	usually have to link against librt or something similar. Enabling it when	2244	usually have to link against librt or something similar. Enabling it when
1597	the functionality isn't available is safe, though, althoguh you have	2245	the functionality isn't available is safe, though, although you have
1598	to make sure you link against any libraries where the C<clock_gettime>	2246	to make sure you link against any libraries where the C<clock_gettime>
1599	function is hiding in (often F<-lrt>).	2247	function is hiding in (often F<-lrt>).
1600		2248
1601	=item EV_USE_REALTIME	2249	=item EV_USE_REALTIME
1602		2250
1603	If defined to be C<1>, libev will try to detect the availability of the	2251	If defined to be C<1>, libev will try to detect the availability of the
1604	realtime clock option at compiletime (and assume its availability at	2252	realtime clock option at compiletime (and assume its availability at
1605	runtime if successful). Otherwise no use of the realtime clock option will	2253	runtime if successful). Otherwise no use of the realtime clock option will
1606	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2254	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1607	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2255	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1608	in the description of C<EV_USE_MONOTONIC>, though.	2256	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
1609		2257
1610	=item EV_USE_SELECT	2258	=item EV_USE_SELECT
1611		2259
1612	If undefined or defined to be C<1>, libev will compile in support for the	2260	If undefined or defined to be C<1>, libev will compile in support for the
1613	C<select>(2) backend. No attempt at autodetection will be done: if no	2261	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
1668		2316
1669	=item EV_USE_DEVPOLL	2317	=item EV_USE_DEVPOLL
1670		2318
1671	reserved for future expansion, works like the USE symbols above.	2319	reserved for future expansion, works like the USE symbols above.
1672		2320
		2321	=item EV_USE_INOTIFY
		2322
		2323	If defined to be C<1>, libev will compile in support for the Linux inotify
		2324	interface to speed up C<ev_stat> watchers. Its actual availability will
		2325	be detected at runtime.
		2326
1673	=item EV_H	2327	=item EV_H
1674		2328
1675	The name of the F<ev.h> header file used to include it. The default if	2329	The name of the F<ev.h> header file used to include it. The default if
1676	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2330	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1677	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2331	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
1700	will have the C<struct ev_loop *> as first argument, and you can create	2354	will have the C<struct ev_loop *> as first argument, and you can create
1701	additional independent event loops. Otherwise there will be no support	2355	additional independent event loops. Otherwise there will be no support
1702	for multiple event loops and there is no first event loop pointer	2356	for multiple event loops and there is no first event loop pointer
1703	argument. Instead, all functions act on the single default loop.	2357	argument. Instead, all functions act on the single default loop.
1704		2358
		2359	=item EV_MINPRI
		2360
		2361	=item EV_MAXPRI
		2362
		2363	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2364	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2365	provide for more priorities by overriding those symbols (usually defined
		2366	to be C<-2> and C<2>, respectively).
		2367
		2368	When doing priority-based operations, libev usually has to linearly search
		2369	all the priorities, so having many of them (hundreds) uses a lot of space
		2370	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2371	fine.
		2372
		2373	If your embedding app does not need any priorities, defining these both to
		2374	C<0> will save some memory and cpu.
		2375
1705	=item EV_PERIODICS	2376	=item EV_PERIODIC_ENABLE
1706		2377
1707	If undefined or defined to be C<1>, then periodic timers are supported,	2378	If undefined or defined to be C<1>, then periodic timers are supported. If
1708	otherwise not. This saves a few kb of code.	2379	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2380	code.
		2381
		2382	=item EV_IDLE_ENABLE
		2383
		2384	If undefined or defined to be C<1>, then idle watchers are supported. If
		2385	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2386	code.
		2387
		2388	=item EV_EMBED_ENABLE
		2389
		2390	If undefined or defined to be C<1>, then embed watchers are supported. If
		2391	defined to be C<0>, then they are not.
		2392
		2393	=item EV_STAT_ENABLE
		2394
		2395	If undefined or defined to be C<1>, then stat watchers are supported. If
		2396	defined to be C<0>, then they are not.
		2397
		2398	=item EV_FORK_ENABLE
		2399
		2400	If undefined or defined to be C<1>, then fork watchers are supported. If
		2401	defined to be C<0>, then they are not.
		2402
		2403	=item EV_MINIMAL
		2404
		2405	If you need to shave off some kilobytes of code at the expense of some
		2406	speed, define this symbol to C<1>. Currently only used for gcc to override
		2407	some inlining decisions, saves roughly 30% codesize of amd64.
		2408
		2409	=item EV_PID_HASHSIZE
		2410
		2411	C<ev_child> watchers use a small hash table to distribute workload by
		2412	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2413	than enough. If you need to manage thousands of children you might want to
		2414	increase this value (I<must> be a power of two).
		2415
		2416	=item EV_INOTIFY_HASHSIZE
		2417
		2418	C<ev_staz> watchers use a small hash table to distribute workload by
		2419	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2420	usually more than enough. If you need to manage thousands of C<ev_stat>
		2421	watchers you might want to increase this value (I<must> be a power of
		2422	two).
1709		2423
1710	=item EV_COMMON	2424	=item EV_COMMON
1711		2425
1712	By default, all watchers have a C<void *data> member. By redefining	2426	By default, all watchers have a C<void *data> member. By redefining
1713	this macro to a something else you can include more and other types of	2427	this macro to a something else you can include more and other types of
…		…
1726		2440
1727	=item ev_set_cb (ev, cb)	2441	=item ev_set_cb (ev, cb)
1728		2442
1729	Can be used to change the callback member declaration in each watcher,	2443	Can be used to change the callback member declaration in each watcher,
1730	and the way callbacks are invoked and set. Must expand to a struct member	2444	and the way callbacks are invoked and set. Must expand to a struct member
1731	definition and a statement, respectively. See the F<ev.v> header file for	2445	definition and a statement, respectively. See the F<ev.c> header file for
1732	their default definitions. One possible use for overriding these is to	2446	their default definitions. One possible use for overriding these is to
1733	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2447	avoid the C<struct ev_loop *> as first argument in all cases, or to use
1734	method calls instead of plain function calls in C++.	2448	method calls instead of plain function calls in C++.
		2449
		2450	=head2 EXPORTED API SYMBOLS
		2451
		2452	If you need to re-export the API (e.g. via a dll) and you need a list of
		2453	exported symbols, you can use the provided F<Symbol.*> files which list
		2454	all public symbols, one per line:
		2455
		2456	Symbols.ev for libev proper
		2457	Symbols.event for the libevent emulation
		2458
		2459	This can also be used to rename all public symbols to avoid clashes with
		2460	multiple versions of libev linked together (which is obviously bad in
		2461	itself, but sometimes it is inconvinient to avoid this).
		2462
		2463	A sed command like this will create wrapper C<#define>'s that you need to
		2464	include before including F<ev.h>:
		2465
		2466	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2467
		2468	This would create a file F<wrap.h> which essentially looks like this:
		2469
		2470	#define ev_backend myprefix_ev_backend
		2471	#define ev_check_start myprefix_ev_check_start
		2472	#define ev_check_stop myprefix_ev_check_stop
		2473	...
1735		2474
1736	=head2 EXAMPLES	2475	=head2 EXAMPLES
1737		2476
1738	For a real-world example of a program the includes libev	2477	For a real-world example of a program the includes libev
1739	verbatim, you can have a look at the EV perl module	2478	verbatim, you can have a look at the EV perl module
…		…
1742	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2481	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
1743	will be compiled. It is pretty complex because it provides its own header	2482	will be compiled. It is pretty complex because it provides its own header
1744	file.	2483	file.
1745		2484
1746	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2485	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
1747	that everybody includes and which overrides some autoconf choices:	2486	that everybody includes and which overrides some configure choices:
1748		2487
		2488	#define EV_MINIMAL 1
1749	#define EV_USE_POLL 0	2489	#define EV_USE_POLL 0
1750	#define EV_MULTIPLICITY 0	2490	#define EV_MULTIPLICITY 0
1751	#define EV_PERIODICS 0	2491	#define EV_PERIODIC_ENABLE 0
		2492	#define EV_STAT_ENABLE 0
		2493	#define EV_FORK_ENABLE 0
1752	#define EV_CONFIG_H <config.h>	2494	#define EV_CONFIG_H <config.h>
		2495	#define EV_MINPRI 0
		2496	#define EV_MAXPRI 0
1753		2497
1754	#include "ev++.h"	2498	#include "ev++.h"
1755		2499
1756	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2500	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1757		2501
…		…
1763		2507
1764	In this section the complexities of (many of) the algorithms used inside	2508	In this section the complexities of (many of) the algorithms used inside
1765	libev will be explained. For complexity discussions about backends see the	2509	libev will be explained. For complexity discussions about backends see the
1766	documentation for C<ev_default_init>.	2510	documentation for C<ev_default_init>.
1767		2511
		2512	All of the following are about amortised time: If an array needs to be
		2513	extended, libev needs to realloc and move the whole array, but this
		2514	happens asymptotically never with higher number of elements, so O(1) might
		2515	mean it might do a lengthy realloc operation in rare cases, but on average
		2516	it is much faster and asymptotically approaches constant time.
		2517
1768	=over 4	2518	=over 4
1769		2519
1770	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2520	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
1771		2521
		2522	This means that, when you have a watcher that triggers in one hour and
		2523	there are 100 watchers that would trigger before that then inserting will
		2524	have to skip those 100 watchers.
		2525
1772	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2526	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
1773		2527
		2528	That means that for changing a timer costs less than removing/adding them
		2529	as only the relative motion in the event queue has to be paid for.
		2530
1774	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2531	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
1775		2532
		2533	These just add the watcher into an array or at the head of a list.
1776	=item Stopping check/prepare/idle watchers: O(1)	2534	=item Stopping check/prepare/idle watchers: O(1)
1777		2535
1778	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2536	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2537
		2538	These watchers are stored in lists then need to be walked to find the
		2539	correct watcher to remove. The lists are usually short (you don't usually
		2540	have many watchers waiting for the same fd or signal).
1779		2541
1780	=item Finding the next timer per loop iteration: O(1)	2542	=item Finding the next timer per loop iteration: O(1)
1781		2543
1782	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2544	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
1783		2545
		2546	A change means an I/O watcher gets started or stopped, which requires
		2547	libev to recalculate its status (and possibly tell the kernel).
		2548
1784	=item Activating one watcher: O(1)	2549	=item Activating one watcher: O(1)
1785		2550
		2551	=item Priority handling: O(number_of_priorities)
		2552
		2553	Priorities are implemented by allocating some space for each
		2554	priority. When doing priority-based operations, libev usually has to
		2555	linearly search all the priorities.
		2556
1786	=back	2557	=back
1787		2558
1788		2559
1789	=head1 AUTHOR	2560	=head1 AUTHOR
1790		2561

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