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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
		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>.
10		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 occuring), 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
…		…
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
…		…
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>.
…		…
361	=item ev_loop_fork (loop)	447	=item ev_loop_fork (loop)
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.
		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.
366		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.
…		…
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
		569
472		570
473	=head1 ANATOMY OF A WATCHER	571	=head1 ANATOMY OF A WATCHER
474		572
475	A watcher is a structure that you create and register to record your	573	A watcher is a structure that you create and register to record your
476	interest in some event. For instance, if you want to wait for STDIN to	574	interest in some event. For instance, if you want to wait for STDIN to
…		…
543	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.
544		642
545	=item C<EV_CHILD>	643	=item C<EV_CHILD>
546		644
547	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.
548		650
549	=item C<EV_IDLE>	651	=item C<EV_IDLE>
550		652
551	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.
552		654
…		…
560	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
561	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
562	(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
563	C<ev_loop> from blocking).	665	C<ev_loop> from blocking).
564		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
565	=item C<EV_ERROR>	676	=item C<EV_ERROR>
566		677
567	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
568	happen because the watcher could not be properly started because libev	679	happen because the watcher could not be properly started because libev
569	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
…		…
576	with the error from read() or write(). This will not work in multithreaded	687	with the error from read() or write(). This will not work in multithreaded
577	programs, though, so beware.	688	programs, though, so beware.
578		689
579	=back	690	=back
580		691
581	=head2 SUMMARY OF GENERIC WATCHER FUNCTIONS	692	=head2 GENERIC WATCHER FUNCTIONS
582		693
583	In the following description, C<TYPE> stands for the watcher type,	694	In the following description, C<TYPE> stands for the watcher type,
584	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.	695	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.
585		696
586	=over 4	697	=over 4
…		…
595	which rolls both calls into one.	706	which rolls both calls into one.
596		707
597	You can reinitialise a watcher at any time as long as it has been stopped	708	You can reinitialise a watcher at any time as long as it has been stopped
598	(or never started) and there are no pending events outstanding.	709	(or never started) and there are no pending events outstanding.
599		710
600	The callbakc is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher,	711	The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher,
601	int revents)>.	712	int revents)>.
602		713
603	=item C<ev_TYPE_set> (ev_TYPE *, [args])	714	=item C<ev_TYPE_set> (ev_TYPE *, [args])
604		715
605	This macro initialises the type-specific parts of a watcher. You need to	716	This macro initialises the type-specific parts of a watcher. You need to
…		…
640	=item bool ev_is_pending (ev_TYPE *watcher)	751	=item bool ev_is_pending (ev_TYPE *watcher)
641		752
642	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
643	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
644	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
645	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
646	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).
647		759
648	=item callback = ev_cb (ev_TYPE *watcher)	760	=item callback ev_cb (ev_TYPE *watcher)
649		761
650	Returns the callback currently set on the watcher.	762	Returns the callback currently set on the watcher.
651		763
652	=item ev_cb_set (ev_TYPE *watcher, callback)	764	=item ev_cb_set (ev_TYPE *watcher, callback)
653		765
654	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
655	(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>.
656		808
657	=back	809	=back
658		810
659		811
660	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	812	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
681	{	833	{
682	struct my_io *w = (struct my_io *)w_;	834	struct my_io *w = (struct my_io *)w_;
683	...	835	...
684	}	836	}
685		837
686	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
687	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	}
688		869
689		870
690	=head1 WATCHER TYPES	871	=head1 WATCHER TYPES
691		872
692	This section describes each watcher in detail, but will not repeat	873	This section describes each watcher in detail, but will not repeat
693	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.
694		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
		886
696	=head2 C<ev_io> - is this file descriptor readable or writable	887	=head2 C<ev_io> - is this file descriptor readable or writable?
697		888
698	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
699	in each iteration of the event loop (This behaviour is called	890	in each iteration of the event loop, or, more precisely, when reading
700	level-triggering because you keep receiving events as long as the	891	would not block the process and writing would at least be able to write
701	condition persists. Remember you can stop the watcher if you don't want to	892	some data. This behaviour is called level-triggering because you keep
702	act on the event and neither want to receive future events).	893	receiving events as long as the condition persists. Remember you can stop
		894	the watcher if you don't want to act on the event and neither want to
		895	receive future events.
703		896
704	In general you can register as many read and/or write event watchers per	897	In general you can register as many read and/or write event watchers per
705	fd as you want (as long as you don't confuse yourself). Setting all file	898	fd as you want (as long as you don't confuse yourself). Setting all file
706	descriptors to non-blocking mode is also usually a good idea (but not	899	descriptors to non-blocking mode is also usually a good idea (but not
707	required if you know what you are doing).	900	required if you know what you are doing).
708		901
709	You have to be careful with dup'ed file descriptors, though. Some backends	902	You have to be careful with dup'ed file descriptors, though. Some backends
710	(the linux epoll backend is a notable example) cannot handle dup'ed file	903	(the linux epoll backend is a notable example) cannot handle dup'ed file
711	descriptors correctly if you register interest in two or more fds pointing	904	descriptors correctly if you register interest in two or more fds pointing
712	to the same underlying file/socket etc. description (that is, they share	905	to the same underlying file/socket/etc. description (that is, they share
713	the same underlying "file open").	906	the same underlying "file open").
714		907
715	If you must do this, then force the use of a known-to-be-good backend	908	If you must do this, then force the use of a known-to-be-good backend
716	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	909	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
717	C<EVBACKEND_POLL>).	910	C<EVBACKEND_POLL>).
718		911
		912	Another thing you have to watch out for is that it is quite easy to
		913	receive "spurious" readyness notifications, that is your callback might
		914	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
		915	because there is no data. Not only are some backends known to create a
		916	lot of those (for example solaris ports), it is very easy to get into
		917	this situation even with a relatively standard program structure. Thus
		918	it is best to always use non-blocking I/O: An extra C<read>(2) returning
		919	C<EAGAIN> is far preferable to a program hanging until some data arrives.
		920
		921	If you cannot run the fd in non-blocking mode (for example you should not
		922	play around with an Xlib connection), then you have to seperately re-test
		923	whether a file descriptor is really ready with a known-to-be good interface
		924	such as poll (fortunately in our Xlib example, Xlib already does this on
		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
		950
719	=over 4	951	=over 4
720		952
721	=item ev_io_init (ev_io *, callback, int fd, int events)	953	=item ev_io_init (ev_io *, callback, int fd, int events)
722		954
723	=item ev_io_set (ev_io *, int fd, int events)	955	=item ev_io_set (ev_io *, int fd, int events)
724		956
725	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive	957	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
726	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ |	958	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
727	EV_WRITE> to receive the given events.	959	C<EV_READ | EV_WRITE> to receive the given events.
728		960
729	Please note that most of the more scalable backend mechanisms (for example	961	=item int fd [read-only]
730	epoll and solaris ports) can result in spurious readyness notifications	962
731	for file descriptors, so you practically need to use non-blocking I/O (and	963	The file descriptor being watched.
732	treat callback invocation as hint only), or retest separately with a safe	964
733	interface before doing I/O (XLib can do this), or force the use of either	965	=item int events [read-only]
734	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this	966
735	problem. Also note that it is quite easy to have your callback invoked	967	The events being watched.
736	when the readyness condition is no longer valid even when employing
737	typical ways of handling events, so its a good idea to use non-blocking
738	I/O unconditionally.
739		968
740	=back	969	=back
741		970
742	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
743	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
744	attempt to read a whole line in the callback:	973	attempt to read a whole line in the callback.
745		974
746	static void	975	static void
747	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)
748	{	977	{
749	ev_io_stop (loop, w);	978	ev_io_stop (loop, w);
…		…
756	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	985	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
757	ev_io_start (loop, &stdin_readable);	986	ev_io_start (loop, &stdin_readable);
758	ev_loop (loop, 0);	987	ev_loop (loop, 0);
759		988
760		989
761	=head2 C<ev_timer> - relative and optionally recurring timeouts	990	=head2 C<ev_timer> - relative and optionally repeating timeouts
762		991
763	Timer watchers are simple relative timers that generate an event after a	992	Timer watchers are simple relative timers that generate an event after a
764	given time, and optionally repeating in regular intervals after that.	993	given time, and optionally repeating in regular intervals after that.
765		994
766	The timers are based on real time, that is, if you register an event that	995	The timers are based on real time, that is, if you register an event that
…		…
779		1008
780	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,
781	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
782	order of execution is undefined.	1011	order of execution is undefined.
783		1012
		1013	=head3 Watcher-Specific Functions and Data Members
		1014
784	=over 4	1015	=over 4
785		1016
786	=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)
787		1018
788	=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)
…		…
801	=item ev_timer_again (loop)	1032	=item ev_timer_again (loop)
802		1033
803	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
804	repeating. The exact semantics are:	1035	repeating. The exact semantics are:
805		1036
		1037	If the timer is pending, its pending status is cleared.
		1038
806	If the timer is started but nonrepeating, stop it.	1039	If the timer is started but nonrepeating, stop it (as if it timed out).
807		1040
808	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
809	value), or reset the running timer to the repeat value.	1042	C<repeat> value), or reset the running timer to the C<repeat> value.
810		1043
811	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
812	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
813	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
814	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
815	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
816	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
817	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
818	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.
819		1074
820	=back	1075	=back
821		1076
822	Example: create a timer that fires after 60 seconds.	1077	Example: Create a timer that fires after 60 seconds.
823		1078
824	static void	1079	static void
825	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)
826	{	1081	{
827	.. one minute over, w is actually stopped right here	1082	.. one minute over, w is actually stopped right here
…		…
829		1084
830	struct ev_timer mytimer;	1085	struct ev_timer mytimer;
831	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1086	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
832	ev_timer_start (loop, &mytimer);	1087	ev_timer_start (loop, &mytimer);
833		1088
834	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
835	inactivity.	1090	inactivity.
836		1091
837	static void	1092	static void
838	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)
839	{	1094	{
…		…
848	// and in some piece of code that gets executed on any "activity":	1103	// and in some piece of code that gets executed on any "activity":
849	// reset the timeout to start ticking again at 10 seconds	1104	// reset the timeout to start ticking again at 10 seconds
850	ev_timer_again (&mytimer);	1105	ev_timer_again (&mytimer);
851		1106
852		1107
853	=head2 C<ev_periodic> - to cron or not to cron	1108	=head2 C<ev_periodic> - to cron or not to cron?
854		1109
855	Periodic watchers are also timers of a kind, but they are very versatile	1110	Periodic watchers are also timers of a kind, but they are very versatile
856	(and unfortunately a bit complex).	1111	(and unfortunately a bit complex).
857		1112
858	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1113	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
859	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
860	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
861	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 ()
862	+ 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
863	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
864	roughly 10 seconds later and of course not if you reset your system time	1119	roughly 10 seconds later).
865	again).
866		1120
867	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
868	triggering an event on eahc midnight, local time.	1122	triggering an event on each midnight, local time or other, complicated,
		1123	rules.
869		1124
870	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
871	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
872	during the same loop iteration then order of execution is undefined.	1127	during the same loop iteration then order of execution is undefined.
873		1128
		1129	=head3 Watcher-Specific Functions and Data Members
		1130
874	=over 4	1131	=over 4
875		1132
876	=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)
877		1134
878	=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)
…		…
880	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
881	operation, and we will explain them from simplest to complex:	1138	operation, and we will explain them from simplest to complex:
882		1139
883	=over 4	1140	=over 4
884		1141
885	=item * absolute timer (interval = reschedule_cb = 0)	1142	=item * absolute timer (at = time, interval = reschedule_cb = 0)
886		1143
887	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
888	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,
889	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
890	system time reaches or surpasses this time.	1147	system time reaches or surpasses this time.
891		1148
892	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1149	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
893		1150
894	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
895	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)
896	of any time jumps.	1153	and then repeat, regardless of any time jumps.
897		1154
898	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
899	time:	1156	time:
900		1157
901	ev_periodic_set (&periodic, 0., 3600., 0);	1158	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
907		1164
908	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
909	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
910	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.
911		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
912	=item * manual reschedule mode (reschedule_cb = callback)	1173	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
913		1174
914	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
915	ignored. Instead, each time the periodic watcher gets scheduled, the	1176	ignored. Instead, each time the periodic watcher gets scheduled, the
916	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
917	current time as second argument.	1178	current time as second argument.
918		1179
919	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,
920	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,
921	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
922	starting a prepare watcher).	1183	starting an C<ev_prepare> watcher, which is legal).
923		1184
924	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,
925	ev_tstamp now)>, e.g.:	1186	ev_tstamp now)>, e.g.:
926		1187
927	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)
…		…
950	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
951	when you changed some parameters or the reschedule callback would return	1212	when you changed some parameters or the reschedule callback would return
952	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
953	program when the crontabs have changed).	1214	program when the crontabs have changed).
954		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
955	=back	1241	=back
956		1242
957	Example: call a callback every hour, or, more precisely, whenever the	1243	Example: Call a callback every hour, or, more precisely, whenever the
958	system clock is divisible by 3600. The callback invocation times have	1244	system clock is divisible by 3600. The callback invocation times have
959	potentially a lot of jittering, but good long-term stability.	1245	potentially a lot of jittering, but good long-term stability.
960		1246
961	static void	1247	static void
962	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)
…		…
966		1252
967	struct ev_periodic hourly_tick;	1253	struct ev_periodic hourly_tick;
968	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1254	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
969	ev_periodic_start (loop, &hourly_tick);	1255	ev_periodic_start (loop, &hourly_tick);
970		1256
971	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:
972		1258
973	#include <math.h>	1259	#include <math.h>
974		1260
975	static ev_tstamp	1261	static ev_tstamp
976	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1262	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
978	return fmod (now, 3600.) + 3600.;	1264	return fmod (now, 3600.) + 3600.;
979	}	1265	}
980		1266
981	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);
982		1268
983	Example: call a callback every hour, starting now:	1269	Example: Call a callback every hour, starting now:
984		1270
985	struct ev_periodic hourly_tick;	1271	struct ev_periodic hourly_tick;
986	ev_periodic_init (&hourly_tick, clock_cb,	1272	ev_periodic_init (&hourly_tick, clock_cb,
987	fmod (ev_now (loop), 3600.), 3600., 0);	1273	fmod (ev_now (loop), 3600.), 3600., 0);
988	ev_periodic_start (loop, &hourly_tick);	1274	ev_periodic_start (loop, &hourly_tick);
989		1275
990		1276
991	=head2 C<ev_signal> - signal me when a signal gets signalled	1277	=head2 C<ev_signal> - signal me when a signal gets signalled!
992		1278
993	Signal watchers will trigger an event when the process receives a specific	1279	Signal watchers will trigger an event when the process receives a specific
994	signal one or more times. Even though signals are very asynchronous, libev	1280	signal one or more times. Even though signals are very asynchronous, libev
995	will try it's best to deliver signals synchronously, i.e. as part of the	1281	will try it's best to deliver signals synchronously, i.e. as part of the
996	normal event processing, like any other event.	1282	normal event processing, like any other event.
…		…
1000	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
1001	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
1002	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
1003	SIG_DFL (regardless of what it was set to before).	1289	SIG_DFL (regardless of what it was set to before).
1004		1290
		1291	=head3 Watcher-Specific Functions and Data Members
		1292
1005	=over 4	1293	=over 4
1006		1294
1007	=item ev_signal_init (ev_signal *, callback, int signum)	1295	=item ev_signal_init (ev_signal *, callback, int signum)
1008		1296
1009	=item ev_signal_set (ev_signal *, int signum)	1297	=item ev_signal_set (ev_signal *, int signum)
1010		1298
1011	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
1012	of the C<SIGxxx> constants).	1300	of the C<SIGxxx> constants).
1013		1301
		1302	=item int signum [read-only]
		1303
		1304	The signal the watcher watches out for.
		1305
1014	=back	1306	=back
1015		1307
1016		1308
1017	=head2 C<ev_child> - wait for pid status changes	1309	=head2 C<ev_child> - watch out for process status changes
1018		1310
1019	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
1020	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
1021		1315
1022	=over 4	1316	=over 4
1023		1317
1024	=item ev_child_init (ev_child *, callback, int pid)	1318	=item ev_child_init (ev_child *, callback, int pid)
1025		1319
…		…
1030	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
1031	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
1032	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
1033	process causing the status change.	1327	process causing the status change.
1034		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
1035	=back	1342	=back
1036		1343
1037	Example: try to exit cleanly on SIGINT and SIGTERM.	1344	Example: Try to exit cleanly on SIGINT and SIGTERM.
1038		1345
1039	static void	1346	static void
1040	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)
1041	{	1348	{
1042	ev_unloop (loop, EVUNLOOP_ALL);	1349	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1045	struct ev_signal signal_watcher;	1352	struct ev_signal signal_watcher;
1046	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1353	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1047	ev_signal_start (loop, &sigint_cb);	1354	ev_signal_start (loop, &sigint_cb);
1048		1355
1049		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
1050	=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...
1051		1466
1052	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
1053	(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
1054	as your process is busy handling sockets or timeouts (or even signals,	1469	count).
1055	imagine) it will not be triggered. But when your process is idle all idle	1470
1056	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
1057	until stopped, that is, or your process receives more events and becomes	1475	iteration - until stopped, that is, or your process receives more events
1058	busy.	1476	and becomes busy again with higher priority stuff.
1059		1477
1060	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
1061	active, the process will not block when waiting for new events.	1479	active, the process will not block when waiting for new events.
1062		1480
1063	Apart from keeping your process non-blocking (which is a useful	1481	Apart from keeping your process non-blocking (which is a useful
1064	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
1065	"pseudo-background processing", or delay processing stuff to after the	1483	"pseudo-background processing", or delay processing stuff to after the
1066	event loop has handled all outstanding events.	1484	event loop has handled all outstanding events.
1067		1485
		1486	=head3 Watcher-Specific Functions and Data Members
		1487
1068	=over 4	1488	=over 4
1069		1489
1070	=item ev_idle_init (ev_signal *, callback)	1490	=item ev_idle_init (ev_signal *, callback)
1071		1491
1072	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
1073	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,
1074	believe me.	1494	believe me.
1075		1495
1076	=back	1496	=back
1077		1497
1078	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
1079	callback, free it. Alos, use no error checking, as usual.	1499	callback, free it. Also, use no error checking, as usual.
1080		1500
1081	static void	1501	static void
1082	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)
1083	{	1503	{
1084	free (w);	1504	free (w);
…		…
1089	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1509	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1090	ev_idle_init (idle_watcher, idle_cb);	1510	ev_idle_init (idle_watcher, idle_cb);
1091	ev_idle_start (loop, idle_cb);	1511	ev_idle_start (loop, idle_cb);
1092		1512
1093		1513
1094	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	1514	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1095		1515
1096	Prepare and check watchers are usually (but not always) used in tandem:	1516	Prepare and check watchers are usually (but not always) used in tandem:
1097	prepare watchers get invoked before the process blocks and check watchers	1517	prepare watchers get invoked before the process blocks and check watchers
1098	afterwards.	1518	afterwards.
1099		1519
		1520	You I<must not> call C<ev_loop> or similar functions that enter
		1521	the current event loop from either C<ev_prepare> or C<ev_check>
		1522	watchers. Other loops than the current one are fine, however. The
		1523	rationale behind this is that you do not need to check for recursion in
		1524	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
		1525	C<ev_check> so if you have one watcher of each kind they will always be
		1526	called in pairs bracketing the blocking call.
		1527
1100	Their main purpose is to integrate other event mechanisms into libev and	1528	Their main purpose is to integrate other event mechanisms into libev and
1101	their use is somewhat advanced. This could be used, for example, to track	1529	their use is somewhat advanced. This could be used, for example, to track
1102	variable changes, implement your own watchers, integrate net-snmp or a	1530	variable changes, implement your own watchers, integrate net-snmp or a
1103	coroutine library and lots more.	1531	coroutine library and lots more. They are also occasionally useful if
		1532	you cache some data and want to flush it before blocking (for example,
		1533	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
		1534	watcher).
1104		1535
1105	This is done by examining in each prepare call which file descriptors need	1536	This is done by examining in each prepare call which file descriptors need
1106	to be watched by the other library, registering C<ev_io> watchers for	1537	to be watched by the other library, registering C<ev_io> watchers for
1107	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1538	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1108	provide just this functionality). Then, in the check watcher you check for	1539	provide just this functionality). Then, in the check watcher you check for
…		…
1118	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
1119	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
1120	loop from blocking if lower-priority coroutines are active, thus mapping	1551	loop from blocking if lower-priority coroutines are active, thus mapping
1121	low-priority coroutines to idle/background tasks).	1552	low-priority coroutines to idle/background tasks).
1122		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
1123	=over 4	1566	=over 4
1124		1567
1125	=item ev_prepare_init (ev_prepare *, callback)	1568	=item ev_prepare_init (ev_prepare *, callback)
1126		1569
1127	=item ev_check_init (ev_check *, callback)	1570	=item ev_check_init (ev_check *, callback)
…		…
1130	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>
1131	macros, but using them is utterly, utterly and completely pointless.	1574	macros, but using them is utterly, utterly and completely pointless.
1132		1575
1133	=back	1576	=back
1134		1577
1135	Example: *TODO*.	1578	There are a number of principal ways to embed other event loops or modules
		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).
1136		1584
		1585	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
		1586	and in a check watcher, destroy them and call into libadns. What follows
		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.
1137		1590
		1591	static ev_io iow [nfd];
		1592	static ev_timer tw;
		1593
		1594	static void
		1595	io_cb (ev_loop *loop, ev_io *w, int revents)
		1596	{
		1597	}
		1598
		1599	// create io watchers for each fd and a timer before blocking
		1600	static void
		1601	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
		1602	{
		1603	int timeout = 3600000;
		1604	struct pollfd fds [nfd];
		1605	// actual code will need to loop here and realloc etc.
		1606	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1607
		1608	/* the callback is illegal, but won't be called as we stop during check */
		1609	ev_timer_init (&tw, 0, timeout * 1e-3);
		1610	ev_timer_start (loop, &tw);
		1611
		1612	// create one ev_io per pollfd
		1613	for (int i = 0; i < nfd; ++i)
		1614	{
		1615	ev_io_init (iow + i, io_cb, fds [i].fd,
		1616	((fds [i].events & POLLIN ? EV_READ : 0)
		1617	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1618
		1619	fds [i].revents = 0;
		1620	ev_io_start (loop, iow + i);
		1621	}
		1622	}
		1623
		1624	// stop all watchers after blocking
		1625	static void
		1626	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
		1627	{
		1628	ev_timer_stop (loop, &tw);
		1629
		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
		1640	ev_io_stop (loop, iow + i);
		1641	}
		1642
		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;
		1703	}
		1704
		1705
1138	=head2 C<ev_embed> - when one backend isn't enough	1706	=head2 C<ev_embed> - when one backend isn't enough...
1139		1707
1140	This is a rather advanced watcher type that lets you embed one event loop	1708	This is a rather advanced watcher type that lets you embed one event loop
1141	into another (currently only C<ev_io> events are supported in the embedded	1709	into another (currently only C<ev_io> events are supported in the embedded
1142	loop, other types of watchers might be handled in a delayed or incorrect	1710	loop, other types of watchers might be handled in a delayed or incorrect
1143	fashion and must not be used).	1711	fashion and must not be used).
…		…
1203	ev_embed_start (loop_hi, &embed);	1771	ev_embed_start (loop_hi, &embed);
1204	}	1772	}
1205	else	1773	else
1206	loop_lo = loop_hi;	1774	loop_lo = loop_hi;
1207		1775
		1776	=head3 Watcher-Specific Functions and Data Members
		1777
1208	=over 4	1778	=over 4
1209		1779
1210	=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)
1211		1781
1212	=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)
…		…
1221		1791
1222	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
1223	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
1224	apropriate way for embedded loops.	1794	apropriate way for embedded loops.
1225		1795
		1796	=item struct ev_loop *loop [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
1226	=back	1823	=back
1227		1824
1228		1825
1229	=head1 OTHER FUNCTIONS	1826	=head1 OTHER FUNCTIONS
1230		1827
…		…
1318		1915
1319	To use it,	1916	To use it,
1320		1917
1321	#include <ev++.h>	1918	#include <ev++.h>
1322		1919
1323	(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
1324	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
1325	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>.
1326		1924
1327	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++
1328	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).
1329		1935
1330	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:
1331		1937
1332	=over 4	1938	=over 4
1333		1939
…		…
1349		1955
1350	All of those classes have these methods:	1956	All of those classes have these methods:
1351		1957
1352	=over 4	1958	=over 4
1353		1959
1354	=item ev::TYPE::TYPE (object *, object::method *)	1960	=item ev::TYPE::TYPE ()
1355		1961
1356	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)	1962	=item ev::TYPE::TYPE (struct ev_loop *)
1357		1963
1358	=item ev::TYPE::~TYPE	1964	=item ev::TYPE::~TYPE
1359		1965
1360	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
1361	the event handler callback to call in this class. The constructor calls	1967	with. If it is omitted, it will use C<EV_DEFAULT>.
1362	C<ev_init> for you, which means you have to call the C<set> method	1968
1363	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
1364	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).
1365		1977
1366	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> ();
1367		2018
1368	=item w->set (struct ev_loop *)	2019	=item w->set (struct ev_loop *)
1369		2020
1370	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
1371	do this when the watcher is inactive (and not pending either).	2022	do this when the watcher is inactive (and not pending either).
1372		2023
1373	=item w->set ([args])	2024	=item w->set ([args])
1374		2025
1375	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
1376	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
1377	automatically stopped and restarted.	2028	automatically stopped and restarted when reconfiguring it with this
		2029	method.
1378		2030
1379	=item w->start ()	2031	=item w->start ()
1380		2032
1381	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
1382	constructor already takes the loop.	2034	constructor already stores the event loop.
1383		2035
1384	=item w->stop ()	2036	=item w->stop ()
1385		2037
1386	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.
1387		2039
1388	=item w->again () C<ev::timer>, C<ev::periodic> only	2040	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1389		2041
1390	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
1391	C<ev_TYPE_again> function.	2043	C<ev_TYPE_again> function.
1392		2044
1393	=item w->sweep () C<ev::embed> only	2045	=item w->sweep () (C<ev::embed> only)
1394		2046
1395	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>.
1396		2052
1397	=back	2053	=back
1398		2054
1399	=back	2055	=back
1400		2056
…		…
1408		2064
1409	myclass ();	2065	myclass ();
1410	}	2066	}
1411		2067
1412	myclass::myclass (int fd)	2068	myclass::myclass (int fd)
1413	: io (this, &myclass::io_cb),
1414	idle (this, &myclass::idle_cb)
1415	{	2069	{
		2070	io .set <myclass, &myclass::io_cb > (this);
		2071	idle.set <myclass, &myclass::idle_cb> (this);
		2072
1416	io.start (fd, ev::READ);	2073	io.start (fd, ev::READ);
1417	}	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);
1418		2137
1419	=head1 EMBEDDING	2138	=head1 EMBEDDING
1420		2139
1421	Libev can (and often is) directly embedded into host	2140	Libev can (and often is) directly embedded into host
1422	applications. Examples of applications that embed it include the Deliantra	2141	applications. Examples of applications that embed it include the Deliantra
…		…
1462	ev_vars.h	2181	ev_vars.h
1463	ev_wrap.h	2182	ev_wrap.h
1464		2183
1465	ev_win32.c required on win32 platforms only	2184	ev_win32.c required on win32 platforms only
1466		2185
1467	ev_select.c only when select backend is enabled (which is is by default)	2186	ev_select.c only when select backend is enabled (which is enabled by default)
1468	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)
1469	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)
1470	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)
1471	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)
1472		2191
1473	F<ev.c> includes the backend files directly when enabled, so you only need	2192	F<ev.c> includes the backend files directly when enabled, so you only need
1474	to compile a single file.	2193	to compile this single file.
1475		2194
1476	=head3 LIBEVENT COMPATIBILITY API	2195	=head3 LIBEVENT COMPATIBILITY API
1477		2196
1478	To include the libevent compatibility API, also include:	2197	To include the libevent compatibility API, also include:
1479		2198
…		…
1492		2211
1493	=head3 AUTOCONF SUPPORT	2212	=head3 AUTOCONF SUPPORT
1494		2213
1495	Instead of using C<EV_STANDALONE=1> and providing your config in	2214	Instead of using C<EV_STANDALONE=1> and providing your config in
1496	whatever way you want, you can also C<m4_include([libev.m4])> in your	2215	whatever way you want, you can also C<m4_include([libev.m4])> in your
1497	F<configure.ac> and leave C<EV_STANDALONE> off. F<ev.c> will then include	2216	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
1498	F<config.h> and configure itself accordingly.	2217	include F<config.h> and configure itself accordingly.
1499		2218
1500	For this of course you need the m4 file:	2219	For this of course you need the m4 file:
1501		2220
1502	libev.m4	2221	libev.m4
1503		2222
…		…
1583	otherwise another method will be used as fallback. This is the preferred	2302	otherwise another method will be used as fallback. This is the preferred
1584	backend for BSD and BSD-like systems, although on most BSDs kqueue only	2303	backend for BSD and BSD-like systems, although on most BSDs kqueue only
1585	supports some types of fds correctly (the only platform we found that	2304	supports some types of fds correctly (the only platform we found that
1586	supports ptys for example was NetBSD), so kqueue might be compiled in, but	2305	supports ptys for example was NetBSD), so kqueue might be compiled in, but
1587	not be used unless explicitly requested. The best way to use it is to find	2306	not be used unless explicitly requested. The best way to use it is to find
1588	out wether kqueue supports your type of fd properly and use an embedded	2307	out whether kqueue supports your type of fd properly and use an embedded
1589	kqueue loop.	2308	kqueue loop.
1590		2309
1591	=item EV_USE_PORT	2310	=item EV_USE_PORT
1592		2311
1593	If defined to be C<1>, libev will compile in support for the Solaris	2312	If defined to be C<1>, libev will compile in support for the Solaris
…		…
1596	backend for Solaris 10 systems.	2315	backend for Solaris 10 systems.
1597		2316
1598	=item EV_USE_DEVPOLL	2317	=item EV_USE_DEVPOLL
1599		2318
1600	reserved for future expansion, works like the USE symbols above.	2319	reserved for future expansion, works like the USE symbols above.
		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.
1601		2326
1602	=item EV_H	2327	=item EV_H
1603		2328
1604	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
1605	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
…		…
1629	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
1630	additional independent event loops. Otherwise there will be no support	2355	additional independent event loops. Otherwise there will be no support
1631	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
1632	argument. Instead, all functions act on the single default loop.	2357	argument. Instead, all functions act on the single default loop.
1633		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
1634	=item EV_PERIODICS	2376	=item EV_PERIODIC_ENABLE
1635		2377
1636	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
1637	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).
1638		2423
1639	=item EV_COMMON	2424	=item EV_COMMON
1640		2425
1641	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
1642	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
…		…
1647		2432
1648	#define EV_COMMON \	2433	#define EV_COMMON \
1649	SV *self; /* contains this struct */ \	2434	SV *self; /* contains this struct */ \
1650	SV *cb_sv, *fh /* note no trailing ";" */	2435	SV *cb_sv, *fh /* note no trailing ";" */
1651		2436
1652	=item EV_CB_DECLARE(type)	2437	=item EV_CB_DECLARE (type)
1653		2438
1654	=item EV_CB_INVOKE(watcher,revents)	2439	=item EV_CB_INVOKE (watcher, revents)
1655		2440
1656	=item ev_set_cb(ev,cb)	2441	=item ev_set_cb (ev, cb)
1657		2442
1658	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,
1659	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
1660	definition and a statement, respectively. See the F<ev.v> header file for	2445	definition and a statement, respectively. See the F<ev.v> header file for
1661	their default definitions. One possible use for overriding these is to	2446	their default definitions. One possible use for overriding these is to
1662	avoid the ev_loop pointer as first argument in all cases, or to use method	2447	avoid the C<struct ev_loop *> as first argument in all cases, or to use
1663	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 comamnd 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	...
1664		2474
1665	=head2 EXAMPLES	2475	=head2 EXAMPLES
1666		2476
1667	For a real-world example of a program the includes libev	2477	For a real-world example of a program the includes libev
1668	verbatim, you can have a look at the EV perl module	2478	verbatim, you can have a look at the EV perl module
…		…
1671	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
1672	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
1673	file.	2483	file.
1674		2484
1675	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
1676	that everybody includes and which overrides some autoconf choices:	2486	that everybody includes and which overrides some configure choices:
1677		2487
		2488	#define EV_MINIMAL 1
1678	#define EV_USE_POLL 0	2489	#define EV_USE_POLL 0
1679	#define EV_MULTIPLICITY 0	2490	#define EV_MULTIPLICITY 0
1680	#define EV_PERIODICS 0	2491	#define EV_PERIODIC_ENABLE 0
		2492	#define EV_STAT_ENABLE 0
		2493	#define EV_FORK_ENABLE 0
1681	#define EV_CONFIG_H <config.h>	2494	#define EV_CONFIG_H <config.h>
		2495	#define EV_MINPRI 0
		2496	#define EV_MAXPRI 0
1682		2497
1683	#include "ev++.h"	2498	#include "ev++.h"
1684		2499
1685	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:
1686		2501
1687	#include "rxvttoolkit.h"	2502	#include "ev_cpp.h"
1688
1689	/* darwin has problems with its header files in C++, requiring this namespace juggling */
1690	using namespace ev;
1691
1692	#include "ev.c"	2503	#include "ev.c"
		2504
		2505
		2506	=head1 COMPLEXITIES
		2507
		2508	In this section the complexities of (many of) the algorithms used inside
		2509	libev will be explained. For complexity discussions about backends see the
		2510	documentation for C<ev_default_init>.
		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
		2518	=over 4
		2519
		2520	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
		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
		2526	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
		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
		2531	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
		2532
		2533	These just add the watcher into an array or at the head of a list.
		2534	=item Stopping check/prepare/idle watchers: O(1)
		2535
		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).
		2541
		2542	=item Finding the next timer per loop iteration: O(1)
		2543
		2544	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		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
		2549	=item Activating one watcher: O(1)
		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
		2557	=back
1693		2558
1694		2559
1695	=head1 AUTHOR	2560	=head1 AUTHOR
1696		2561
1697	Marc Lehmann <libev@schmorp.de>.	2562	Marc Lehmann <libev@schmorp.de>.

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