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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 such.
52		104
53
54	=head1 GLOBAL FUNCTIONS	105	=head1 GLOBAL FUNCTIONS
55		106
56	These functions can be called anytime, even before initialising the	107	These functions can be called anytime, even before initialising the
57	library in any way.	108	library in any way.
58		109
…		…
66		117
67	=item int ev_version_major ()	118	=item int ev_version_major ()
68		119
69	=item int ev_version_minor ()	120	=item int ev_version_minor ()
70		121
71	You can find out the major and minor version numbers of the library	122	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	123	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	124	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	125	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
75	version of the library your program was compiled against.	126	version of the library your program was compiled against.
76		127
		128	These version numbers refer to the ABI version of the library, not the
		129	release version.
		130
77	Usually, it's a good idea to terminate if the major versions mismatch,	131	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	132	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	133	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	134	not a problem.
81		135
82	Example: make sure we haven't accidentally been linked against the wrong	136	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	137	version.
84		138
85	assert (("libev version mismatch",	139	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	140	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	141	&& ev_version_minor () >= EV_VERSION_MINOR));
88		142
…		…
118		172
119	See the description of C<ev_embed> watchers for more info.	173	See the description of C<ev_embed> watchers for more info.
120		174
121	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	175	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
122		176
123	Sets the allocation function to use (the prototype is similar to the	177	Sets the allocation function to use (the prototype is similar - the
124	realloc C function, the semantics are identical). It is used to allocate	178	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	179	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	180	memory needs to be allocated, the library might abort or take some
127	destructive action. The default is your system realloc function.	181	potentially destructive action. The default is your system realloc
		182	function.
128		183
129	You could override this function in high-availability programs to, say,	184	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,	185	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.	186	or even to sleep a while and retry until some memory is available.
132		187
133	Example: replace the libev allocator with one that waits a bit and then	188	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	189	retries).
135		190
136	static void *	191	static void *
137	persistent_realloc (void *ptr, long size)	192	persistent_realloc (void *ptr, size_t size)
138	{	193	{
139	for (;;)	194	for (;;)
140	{	195	{
141	void *newptr = realloc (ptr, size);	196	void *newptr = realloc (ptr, size);
142		197
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	213	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	214	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	215	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	216	(such as abort).
162		217
163	Example: do the same thing as libev does internally:	218	Example: This is basically the same thing that libev does internally, too.
164		219
165	static void	220	static void
166	fatal_error (const char *msg)	221	fatal_error (const char *msg)
167	{	222	{
168	perror (msg);	223	perror (msg);
…		…
218	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	273	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
219	override the flags completely if it is found in the environment. This is	274	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	275	useful to try out specific backends to test their performance, or to work
221	around bugs.	276	around bugs.
222		277
		278	=item C<EVFLAG_FORKCHECK>
		279
		280	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		281	a fork, you can also make libev check for a fork in each iteration by
		282	enabling this flag.
		283
		284	This works by calling C<getpid ()> on every iteration of the loop,
		285	and thus this might slow down your event loop if you do a lot of loop
		286	iterations and little real work, but is usually not noticeable (on my
		287	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		288	without a syscall and thus I<very> fast, but my Linux system also has
		289	C<pthread_atfork> which is even faster).
		290
		291	The big advantage of this flag is that you can forget about fork (and
		292	forget about forgetting to tell libev about forking) when you use this
		293	flag.
		294
		295	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		296	environment variable.
		297
223	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	298	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
224		299
225	This is your standard select(2) backend. Not I<completely> standard, as	300	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,	301	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	302	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	389	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	390	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	391	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).	392	undefined behaviour (or a failed assertion if assertions are enabled).
318		393
319	Example: try to create a event loop that uses epoll and nothing else.	394	Example: Try to create a event loop that uses epoll and nothing else.
320		395
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	396	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
322	if (!epoller)	397	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	398	fatal ("no epoll found here, maybe it hides under your chair");
324		399
…		…
362		437
363	Like C<ev_default_fork>, but acts on an event loop created by	438	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	439	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.	440	after fork, and how you do this is entirely your own problem.
366		441
		442	=item unsigned int ev_loop_count (loop)
		443
		444	Returns the count of loop iterations for the loop, which is identical to
		445	the number of times libev did poll for new events. It starts at C<0> and
		446	happily wraps around with enough iterations.
		447
		448	This value can sometimes be useful as a generation counter of sorts (it
		449	"ticks" the number of loop iterations), as it roughly corresponds with
		450	C<ev_prepare> and C<ev_check> calls.
		451
367	=item unsigned int ev_backend (loop)	452	=item unsigned int ev_backend (loop)
368		453
369	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	454	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
370	use.	455	use.
371		456
…		…
404	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	489	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
405	usually a better approach for this kind of thing.	490	usually a better approach for this kind of thing.
406		491
407	Here are the gory details of what C<ev_loop> does:	492	Here are the gory details of what C<ev_loop> does:
408		493
		494	- Before the first iteration, call any pending watchers.
409	* If there are no active watchers (reference count is zero), return.	495	* If there are no active watchers (reference count is zero), return.
410	- Queue prepare watchers and then call all outstanding watchers.	496	- Queue all prepare watchers and then call all outstanding watchers.
411	- If we have been forked, recreate the kernel state.	497	- If we have been forked, recreate the kernel state.
412	- Update the kernel state with all outstanding changes.	498	- Update the kernel state with all outstanding changes.
413	- Update the "event loop time".	499	- Update the "event loop time".
414	- Calculate for how long to block.	500	- Calculate for how long to block.
415	- Block the process, waiting for any events.	501	- Block the process, waiting for any events.
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	509	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	510	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	511	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	512	were used, return, otherwise continue with step *.
427		513
428	Example: queue some jobs and then loop until no events are outsanding	514	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	515	anymore.
430		516
431	... queue jobs here, make sure they register event watchers as long	517	... 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..)	518	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	519	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	539	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	540	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	541	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>.	542	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		543
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	544	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	545	running when nothing else is active.
460		546
461	struct dv_signal exitsig;	547	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	548	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	549	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	550	evf_unref (loop);
465		551
466	Example: for some weird reason, unregister the above signal handler again.	552	Example: For some weird reason, unregister the above signal handler again.
467		553
468	ev_ref (myloop);	554	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	555	ev_signal_stop (loop, &exitsig);
470		556
471	=back	557	=back
		558
472		559
473	=head1 ANATOMY OF A WATCHER	560	=head1 ANATOMY OF A WATCHER
474		561
475	A watcher is a structure that you create and register to record your	562	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	563	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.	630	The signal specified in the C<ev_signal> watcher has been received by a thread.
544		631
545	=item C<EV_CHILD>	632	=item C<EV_CHILD>
546		633
547	The pid specified in the C<ev_child> watcher has received a status change.	634	The pid specified in the C<ev_child> watcher has received a status change.
		635
		636	=item C<EV_STAT>
		637
		638	The path specified in the C<ev_stat> watcher changed its attributes somehow.
548		639
549	=item C<EV_IDLE>	640	=item C<EV_IDLE>
550		641
551	The C<ev_idle> watcher has determined that you have nothing better to do.	642	The C<ev_idle> watcher has determined that you have nothing better to do.
552		643
…		…
560	received events. Callbacks of both watcher types can start and stop as	651	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	652	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	653	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
563	C<ev_loop> from blocking).	654	C<ev_loop> from blocking).
564		655
		656	=item C<EV_EMBED>
		657
		658	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		659
		660	=item C<EV_FORK>
		661
		662	The event loop has been resumed in the child process after fork (see
		663	C<ev_fork>).
		664
565	=item C<EV_ERROR>	665	=item C<EV_ERROR>
566		666
567	An unspecified error has occured, the watcher has been stopped. This might	667	An unspecified error has occured, the watcher has been stopped. This might
568	happen because the watcher could not be properly started because libev	668	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	669	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	676	with the error from read() or write(). This will not work in multithreaded
577	programs, though, so beware.	677	programs, though, so beware.
578		678
579	=back	679	=back
580		680
581	=head2 SUMMARY OF GENERIC WATCHER FUNCTIONS	681	=head2 GENERIC WATCHER FUNCTIONS
582		682
583	In the following description, C<TYPE> stands for the watcher type,	683	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.	684	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.
585		685
586	=over 4	686	=over 4
…		…
595	which rolls both calls into one.	695	which rolls both calls into one.
596		696
597	You can reinitialise a watcher at any time as long as it has been stopped	697	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.	698	(or never started) and there are no pending events outstanding.
599		699
600	The callbakc is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher,	700	The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher,
601	int revents)>.	701	int revents)>.
602		702
603	=item C<ev_TYPE_set> (ev_TYPE *, [args])	703	=item C<ev_TYPE_set> (ev_TYPE *, [args])
604		704
605	This macro initialises the type-specific parts of a watcher. You need to	705	This macro initialises the type-specific parts of a watcher. You need to
…		…
640	=item bool ev_is_pending (ev_TYPE *watcher)	740	=item bool ev_is_pending (ev_TYPE *watcher)
641		741
642	Returns a true value iff the watcher is pending, (i.e. it has outstanding	742	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	743	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	744	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	745	C<ev_TYPE_set> is safe), you must not change its priority, and you must
646	libev (e.g. you cnanot C<free ()> it).	746	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		747	it).
647		748
648	=item callback = ev_cb (ev_TYPE *watcher)	749	=item callback ev_cb (ev_TYPE *watcher)
649		750
650	Returns the callback currently set on the watcher.	751	Returns the callback currently set on the watcher.
651		752
652	=item ev_cb_set (ev_TYPE *watcher, callback)	753	=item ev_cb_set (ev_TYPE *watcher, callback)
653		754
654	Change the callback. You can change the callback at virtually any time	755	Change the callback. You can change the callback at virtually any time
655	(modulo threads).	756	(modulo threads).
		757
		758	=item ev_set_priority (ev_TYPE *watcher, priority)
		759
		760	=item int ev_priority (ev_TYPE *watcher)
		761
		762	Set and query the priority of the watcher. The priority is a small
		763	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		764	(default: C<-2>). Pending watchers with higher priority will be invoked
		765	before watchers with lower priority, but priority will not keep watchers
		766	from being executed (except for C<ev_idle> watchers).
		767
		768	This means that priorities are I<only> used for ordering callback
		769	invocation after new events have been received. This is useful, for
		770	example, to reduce latency after idling, or more often, to bind two
		771	watchers on the same event and make sure one is called first.
		772
		773	If you need to suppress invocation when higher priority events are pending
		774	you need to look at C<ev_idle> watchers, which provide this functionality.
		775
		776	You I<must not> change the priority of a watcher as long as it is active or
		777	pending.
		778
		779	The default priority used by watchers when no priority has been set is
		780	always C<0>, which is supposed to not be too high and not be too low :).
		781
		782	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		783	fine, as long as you do not mind that the priority value you query might
		784	or might not have been adjusted to be within valid range.
		785
		786	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		787
		788	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		789	C<loop> nor C<revents> need to be valid as long as the watcher callback
		790	can deal with that fact.
		791
		792	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		793
		794	If the watcher is pending, this function returns clears its pending status
		795	and returns its C<revents> bitset (as if its callback was invoked). If the
		796	watcher isn't pending it does nothing and returns C<0>.
656		797
657	=back	798	=back
658		799
659		800
660	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	801	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
681	{	822	{
682	struct my_io *w = (struct my_io *)w_;	823	struct my_io *w = (struct my_io *)w_;
683	...	824	...
684	}	825	}
685		826
686	More interesting and less C-conformant ways of catsing your callback type	827	More interesting and less C-conformant ways of casting your callback type
687	have been omitted....	828	instead have been omitted.
		829
		830	Another common scenario is having some data structure with multiple
		831	watchers:
		832
		833	struct my_biggy
		834	{
		835	int some_data;
		836	ev_timer t1;
		837	ev_timer t2;
		838	}
		839
		840	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		841	you need to use C<offsetof>:
		842
		843	#include <stddef.h>
		844
		845	static void
		846	t1_cb (EV_P_ struct ev_timer *w, int revents)
		847	{
		848	struct my_biggy big = (struct my_biggy *
		849	(((char *)w) - offsetof (struct my_biggy, t1));
		850	}
		851
		852	static void
		853	t2_cb (EV_P_ struct ev_timer *w, int revents)
		854	{
		855	struct my_biggy big = (struct my_biggy *
		856	(((char *)w) - offsetof (struct my_biggy, t2));
		857	}
688		858
689		859
690	=head1 WATCHER TYPES	860	=head1 WATCHER TYPES
691		861
692	This section describes each watcher in detail, but will not repeat	862	This section describes each watcher in detail, but will not repeat
693	information given in the last section.	863	information given in the last section. Any initialisation/set macros,
		864	functions and members specific to the watcher type are explained.
694		865
		866	Members are additionally marked with either I<[read-only]>, meaning that,
		867	while the watcher is active, you can look at the member and expect some
		868	sensible content, but you must not modify it (you can modify it while the
		869	watcher is stopped to your hearts content), or I<[read-write]>, which
		870	means you can expect it to have some sensible content while the watcher
		871	is active, but you can also modify it. Modifying it may not do something
		872	sensible or take immediate effect (or do anything at all), but libev will
		873	not crash or malfunction in any way.
695		874
		875
696	=head2 C<ev_io> - is this file descriptor readable or writable	876	=head2 C<ev_io> - is this file descriptor readable or writable?
697		877
698	I/O watchers check whether a file descriptor is readable or writable	878	I/O watchers check whether a file descriptor is readable or writable
699	in each iteration of the event loop (This behaviour is called	879	in each iteration of the event loop, or, more precisely, when reading
700	level-triggering because you keep receiving events as long as the	880	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	881	some data. This behaviour is called level-triggering because you keep
702	act on the event and neither want to receive future events).	882	receiving events as long as the condition persists. Remember you can stop
		883	the watcher if you don't want to act on the event and neither want to
		884	receive future events.
703		885
704	In general you can register as many read and/or write event watchers per	886	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	887	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	888	descriptors to non-blocking mode is also usually a good idea (but not
707	required if you know what you are doing).	889	required if you know what you are doing).
708		890
709	You have to be careful with dup'ed file descriptors, though. Some backends	891	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	892	(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	893	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	894	to the same underlying file/socket/etc. description (that is, they share
713	the same underlying "file open").	895	the same underlying "file open").
714		896
715	If you must do this, then force the use of a known-to-be-good backend	897	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	898	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
717	C<EVBACKEND_POLL>).	899	C<EVBACKEND_POLL>).
718		900
		901	Another thing you have to watch out for is that it is quite easy to
		902	receive "spurious" readyness notifications, that is your callback might
		903	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
		904	because there is no data. Not only are some backends known to create a
		905	lot of those (for example solaris ports), it is very easy to get into
		906	this situation even with a relatively standard program structure. Thus
		907	it is best to always use non-blocking I/O: An extra C<read>(2) returning
		908	C<EAGAIN> is far preferable to a program hanging until some data arrives.
		909
		910	If you cannot run the fd in non-blocking mode (for example you should not
		911	play around with an Xlib connection), then you have to seperately re-test
		912	whether a file descriptor is really ready with a known-to-be good interface
		913	such as poll (fortunately in our Xlib example, Xlib already does this on
		914	its own, so its quite safe to use).
		915
		916	=head3 The special problem of disappearing file descriptors
		917
		918	Some backends (e.g kqueue, epoll) need to be told about closing a file
		919	descriptor (either by calling C<close> explicitly or by any other means,
		920	such as C<dup>). The reason is that you register interest in some file
		921	descriptor, but when it goes away, the operating system will silently drop
		922	this interest. If another file descriptor with the same number then is
		923	registered with libev, there is no efficient way to see that this is, in
		924	fact, a different file descriptor.
		925
		926	To avoid having to explicitly tell libev about such cases, libev follows
		927	the following policy: Each time C<ev_io_set> is being called, libev
		928	will assume that this is potentially a new file descriptor, otherwise
		929	it is assumed that the file descriptor stays the same. That means that
		930	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		931	descriptor even if the file descriptor number itself did not change.
		932
		933	This is how one would do it normally anyway, the important point is that
		934	the libev application should not optimise around libev but should leave
		935	optimisations to libev.
		936
		937
719	=over 4	938	=over 4
720		939
721	=item ev_io_init (ev_io *, callback, int fd, int events)	940	=item ev_io_init (ev_io *, callback, int fd, int events)
722		941
723	=item ev_io_set (ev_io *, int fd, int events)	942	=item ev_io_set (ev_io *, int fd, int events)
724		943
725	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive	944	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 |	945	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
727	EV_WRITE> to receive the given events.	946	C<EV_READ | EV_WRITE> to receive the given events.
728		947
729	Please note that most of the more scalable backend mechanisms (for example	948	=item int fd [read-only]
730	epoll and solaris ports) can result in spurious readyness notifications	949
731	for file descriptors, so you practically need to use non-blocking I/O (and	950	The file descriptor being watched.
732	treat callback invocation as hint only), or retest separately with a safe	951
733	interface before doing I/O (XLib can do this), or force the use of either	952	=item int events [read-only]
734	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this	953
735	problem. Also note that it is quite easy to have your callback invoked	954	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		955
740	=back	956	=back
741		957
742	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	958	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	959	readable, but only once. Since it is likely line-buffered, you could
744	attempt to read a whole line in the callback:	960	attempt to read a whole line in the callback.
745		961
746	static void	962	static void
747	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	963	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
748	{	964	{
749	ev_io_stop (loop, w);	965	ev_io_stop (loop, w);
…		…
756	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	972	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
757	ev_io_start (loop, &stdin_readable);	973	ev_io_start (loop, &stdin_readable);
758	ev_loop (loop, 0);	974	ev_loop (loop, 0);
759		975
760		976
761	=head2 C<ev_timer> - relative and optionally recurring timeouts	977	=head2 C<ev_timer> - relative and optionally repeating timeouts
762		978
763	Timer watchers are simple relative timers that generate an event after a	979	Timer watchers are simple relative timers that generate an event after a
764	given time, and optionally repeating in regular intervals after that.	980	given time, and optionally repeating in regular intervals after that.
765		981
766	The timers are based on real time, that is, if you register an event that	982	The timers are based on real time, that is, if you register an event that
…		…
801	=item ev_timer_again (loop)	1017	=item ev_timer_again (loop)
802		1018
803	This will act as if the timer timed out and restart it again if it is	1019	This will act as if the timer timed out and restart it again if it is
804	repeating. The exact semantics are:	1020	repeating. The exact semantics are:
805		1021
		1022	If the timer is pending, its pending status is cleared.
		1023
806	If the timer is started but nonrepeating, stop it.	1024	If the timer is started but nonrepeating, stop it (as if it timed out).
807		1025
808	If the timer is repeating, either start it if necessary (with the repeat	1026	If the timer is repeating, either start it if necessary (with the
809	value), or reset the running timer to the repeat value.	1027	C<repeat> value), or reset the running timer to the C<repeat> value.
810		1028
811	This sounds a bit complicated, but here is a useful and typical	1029	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	1030	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	1031	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	1032	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	1033	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	1034	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	1035	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.	1036	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
		1037	automatically restart it if need be.
		1038
		1039	That means you can ignore the C<after> value and C<ev_timer_start>
		1040	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
		1041
		1042	ev_timer_init (timer, callback, 0., 5.);
		1043	ev_timer_again (loop, timer);
		1044	...
		1045	timer->again = 17.;
		1046	ev_timer_again (loop, timer);
		1047	...
		1048	timer->again = 10.;
		1049	ev_timer_again (loop, timer);
		1050
		1051	This is more slightly efficient then stopping/starting the timer each time
		1052	you want to modify its timeout value.
		1053
		1054	=item ev_tstamp repeat [read-write]
		1055
		1056	The current C<repeat> value. Will be used each time the watcher times out
		1057	or C<ev_timer_again> is called and determines the next timeout (if any),
		1058	which is also when any modifications are taken into account.
819		1059
820	=back	1060	=back
821		1061
822	Example: create a timer that fires after 60 seconds.	1062	Example: Create a timer that fires after 60 seconds.
823		1063
824	static void	1064	static void
825	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1065	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
826	{	1066	{
827	.. one minute over, w is actually stopped right here	1067	.. one minute over, w is actually stopped right here
…		…
829		1069
830	struct ev_timer mytimer;	1070	struct ev_timer mytimer;
831	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1071	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
832	ev_timer_start (loop, &mytimer);	1072	ev_timer_start (loop, &mytimer);
833		1073
834	Example: create a timeout timer that times out after 10 seconds of	1074	Example: Create a timeout timer that times out after 10 seconds of
835	inactivity.	1075	inactivity.
836		1076
837	static void	1077	static void
838	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1078	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
839	{	1079	{
…		…
848	// and in some piece of code that gets executed on any "activity":	1088	// and in some piece of code that gets executed on any "activity":
849	// reset the timeout to start ticking again at 10 seconds	1089	// reset the timeout to start ticking again at 10 seconds
850	ev_timer_again (&mytimer);	1090	ev_timer_again (&mytimer);
851		1091
852		1092
853	=head2 C<ev_periodic> - to cron or not to cron	1093	=head2 C<ev_periodic> - to cron or not to cron?
854		1094
855	Periodic watchers are also timers of a kind, but they are very versatile	1095	Periodic watchers are also timers of a kind, but they are very versatile
856	(and unfortunately a bit complex).	1096	(and unfortunately a bit complex).
857		1097
858	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1098	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	1099	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	1100	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 ()	1101	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	1102	+ 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	1103	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	1104	roughly 10 seconds later).
865	again).
866		1105
867	They can also be used to implement vastly more complex timers, such as	1106	They can also be used to implement vastly more complex timers, such as
868	triggering an event on eahc midnight, local time.	1107	triggering an event on each midnight, local time or other, complicated,
		1108	rules.
869		1109
870	As with timers, the callback is guarenteed to be invoked only when the	1110	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	1111	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.	1112	during the same loop iteration then order of execution is undefined.
873		1113
…		…
880	Lots of arguments, lets sort it out... There are basically three modes of	1120	Lots of arguments, lets sort it out... There are basically three modes of
881	operation, and we will explain them from simplest to complex:	1121	operation, and we will explain them from simplest to complex:
882		1122
883	=over 4	1123	=over 4
884		1124
885	=item * absolute timer (interval = reschedule_cb = 0)	1125	=item * absolute timer (at = time, interval = reschedule_cb = 0)
886		1126
887	In this configuration the watcher triggers an event at the wallclock time	1127	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,	1128	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	1129	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.	1130	system time reaches or surpasses this time.
891		1131
892	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1132	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
893		1133
894	In this mode the watcher will always be scheduled to time out at the next	1134	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	1135	C<at + N * interval> time (for some integer N, which can also be negative)
896	of any time jumps.	1136	and then repeat, regardless of any time jumps.
897		1137
898	This can be used to create timers that do not drift with respect to system	1138	This can be used to create timers that do not drift with respect to system
899	time:	1139	time:
900		1140
901	ev_periodic_set (&periodic, 0., 3600., 0);	1141	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
907		1147
908	Another way to think about it (for the mathematically inclined) is that	1148	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	1149	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.	1150	time where C<time = at (mod interval)>, regardless of any time jumps.
911		1151
		1152	For numerical stability it is preferable that the C<at> value is near
		1153	C<ev_now ()> (the current time), but there is no range requirement for
		1154	this value.
		1155
912	=item * manual reschedule mode (reschedule_cb = callback)	1156	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
913		1157
914	In this mode the values for C<interval> and C<at> are both being	1158	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	1159	ignored. Instead, each time the periodic watcher gets scheduled, the
916	reschedule callback will be called with the watcher as first, and the	1160	reschedule callback will be called with the watcher as first, and the
917	current time as second argument.	1161	current time as second argument.
918		1162
919	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1163	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,	1164	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	1165	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
922	starting a prepare watcher).	1166	starting an C<ev_prepare> watcher, which is legal).
923		1167
924	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1168	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
925	ev_tstamp now)>, e.g.:	1169	ev_tstamp now)>, e.g.:
926		1170
927	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1171	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	1194	Simply stops and restarts the periodic watcher again. This is only useful
951	when you changed some parameters or the reschedule callback would return	1195	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	1196	a different time than the last time it was called (e.g. in a crond like
953	program when the crontabs have changed).	1197	program when the crontabs have changed).
954		1198
		1199	=item ev_tstamp offset [read-write]
		1200
		1201	When repeating, this contains the offset value, otherwise this is the
		1202	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1203
		1204	Can be modified any time, but changes only take effect when the periodic
		1205	timer fires or C<ev_periodic_again> is being called.
		1206
		1207	=item ev_tstamp interval [read-write]
		1208
		1209	The current interval value. Can be modified any time, but changes only
		1210	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1211	called.
		1212
		1213	=item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]
		1214
		1215	The current reschedule callback, or C<0>, if this functionality is
		1216	switched off. Can be changed any time, but changes only take effect when
		1217	the periodic timer fires or C<ev_periodic_again> is being called.
		1218
955	=back	1219	=back
956		1220
957	Example: call a callback every hour, or, more precisely, whenever the	1221	Example: Call a callback every hour, or, more precisely, whenever the
958	system clock is divisible by 3600. The callback invocation times have	1222	system clock is divisible by 3600. The callback invocation times have
959	potentially a lot of jittering, but good long-term stability.	1223	potentially a lot of jittering, but good long-term stability.
960		1224
961	static void	1225	static void
962	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1226	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
…		…
966		1230
967	struct ev_periodic hourly_tick;	1231	struct ev_periodic hourly_tick;
968	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1232	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
969	ev_periodic_start (loop, &hourly_tick);	1233	ev_periodic_start (loop, &hourly_tick);
970		1234
971	Example: the same as above, but use a reschedule callback to do it:	1235	Example: The same as above, but use a reschedule callback to do it:
972		1236
973	#include <math.h>	1237	#include <math.h>
974		1238
975	static ev_tstamp	1239	static ev_tstamp
976	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1240	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
978	return fmod (now, 3600.) + 3600.;	1242	return fmod (now, 3600.) + 3600.;
979	}	1243	}
980		1244
981	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1245	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
982		1246
983	Example: call a callback every hour, starting now:	1247	Example: Call a callback every hour, starting now:
984		1248
985	struct ev_periodic hourly_tick;	1249	struct ev_periodic hourly_tick;
986	ev_periodic_init (&hourly_tick, clock_cb,	1250	ev_periodic_init (&hourly_tick, clock_cb,
987	fmod (ev_now (loop), 3600.), 3600., 0);	1251	fmod (ev_now (loop), 3600.), 3600., 0);
988	ev_periodic_start (loop, &hourly_tick);	1252	ev_periodic_start (loop, &hourly_tick);
989		1253
990		1254
991	=head2 C<ev_signal> - signal me when a signal gets signalled	1255	=head2 C<ev_signal> - signal me when a signal gets signalled!
992		1256
993	Signal watchers will trigger an event when the process receives a specific	1257	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	1258	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	1259	will try it's best to deliver signals synchronously, i.e. as part of the
996	normal event processing, like any other event.	1260	normal event processing, like any other event.
…		…
1009	=item ev_signal_set (ev_signal *, int signum)	1273	=item ev_signal_set (ev_signal *, int signum)
1010		1274
1011	Configures the watcher to trigger on the given signal number (usually one	1275	Configures the watcher to trigger on the given signal number (usually one
1012	of the C<SIGxxx> constants).	1276	of the C<SIGxxx> constants).
1013		1277
		1278	=item int signum [read-only]
		1279
		1280	The signal the watcher watches out for.
		1281
1014	=back	1282	=back
1015		1283
1016		1284
1017	=head2 C<ev_child> - wait for pid status changes	1285	=head2 C<ev_child> - watch out for process status changes
1018		1286
1019	Child watchers trigger when your process receives a SIGCHLD in response to	1287	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).	1288	some child status changes (most typically when a child of yours dies).
1021		1289
1022	=over 4	1290	=over 4
…		…
1030	at the C<rstatus> member of the C<ev_child> watcher structure to see	1298	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	1299	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	1300	C<waitpid> documentation). The C<rpid> member contains the pid of the
1033	process causing the status change.	1301	process causing the status change.
1034		1302
		1303	=item int pid [read-only]
		1304
		1305	The process id this watcher watches out for, or C<0>, meaning any process id.
		1306
		1307	=item int rpid [read-write]
		1308
		1309	The process id that detected a status change.
		1310
		1311	=item int rstatus [read-write]
		1312
		1313	The process exit/trace status caused by C<rpid> (see your systems
		1314	C<waitpid> and C<sys/wait.h> documentation for details).
		1315
1035	=back	1316	=back
1036		1317
1037	Example: try to exit cleanly on SIGINT and SIGTERM.	1318	Example: Try to exit cleanly on SIGINT and SIGTERM.
1038		1319
1039	static void	1320	static void
1040	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1321	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1041	{	1322	{
1042	ev_unloop (loop, EVUNLOOP_ALL);	1323	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1045	struct ev_signal signal_watcher;	1326	struct ev_signal signal_watcher;
1046	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1327	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1047	ev_signal_start (loop, &sigint_cb);	1328	ev_signal_start (loop, &sigint_cb);
1048		1329
1049		1330
		1331	=head2 C<ev_stat> - did the file attributes just change?
		1332
		1333	This watches a filesystem path for attribute changes. That is, it calls
		1334	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1335	compared to the last time, invoking the callback if it did.
		1336
		1337	The path does not need to exist: changing from "path exists" to "path does
		1338	not exist" is a status change like any other. The condition "path does
		1339	not exist" is signified by the C<st_nlink> field being zero (which is
		1340	otherwise always forced to be at least one) and all the other fields of
		1341	the stat buffer having unspecified contents.
		1342
		1343	The path I<should> be absolute and I<must not> end in a slash. If it is
		1344	relative and your working directory changes, the behaviour is undefined.
		1345
		1346	Since there is no standard to do this, the portable implementation simply
		1347	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1348	can specify a recommended polling interval for this case. If you specify
		1349	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1350	unspecified default> value will be used (which you can expect to be around
		1351	five seconds, although this might change dynamically). Libev will also
		1352	impose a minimum interval which is currently around C<0.1>, but thats
		1353	usually overkill.
		1354
		1355	This watcher type is not meant for massive numbers of stat watchers,
		1356	as even with OS-supported change notifications, this can be
		1357	resource-intensive.
		1358
		1359	At the time of this writing, only the Linux inotify interface is
		1360	implemented (implementing kqueue support is left as an exercise for the
		1361	reader). Inotify will be used to give hints only and should not change the
		1362	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1363	to fall back to regular polling again even with inotify, but changes are
		1364	usually detected immediately, and if the file exists there will be no
		1365	polling.
		1366
		1367	=over 4
		1368
		1369	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
		1370
		1371	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)
		1372
		1373	Configures the watcher to wait for status changes of the given
		1374	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1375	be detected and should normally be specified as C<0> to let libev choose
		1376	a suitable value. The memory pointed to by C<path> must point to the same
		1377	path for as long as the watcher is active.
		1378
		1379	The callback will be receive C<EV_STAT> when a change was detected,
		1380	relative to the attributes at the time the watcher was started (or the
		1381	last change was detected).
		1382
		1383	=item ev_stat_stat (ev_stat *)
		1384
		1385	Updates the stat buffer immediately with new values. If you change the
		1386	watched path in your callback, you could call this fucntion to avoid
		1387	detecting this change (while introducing a race condition). Can also be
		1388	useful simply to find out the new values.
		1389
		1390	=item ev_statdata attr [read-only]
		1391
		1392	The most-recently detected attributes of the file. Although the type is of
		1393	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1394	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1395	was some error while C<stat>ing the file.
		1396
		1397	=item ev_statdata prev [read-only]
		1398
		1399	The previous attributes of the file. The callback gets invoked whenever
		1400	C<prev> != C<attr>.
		1401
		1402	=item ev_tstamp interval [read-only]
		1403
		1404	The specified interval.
		1405
		1406	=item const char *path [read-only]
		1407
		1408	The filesystem path that is being watched.
		1409
		1410	=back
		1411
		1412	Example: Watch C</etc/passwd> for attribute changes.
		1413
		1414	static void
		1415	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
		1416	{
		1417	/* /etc/passwd changed in some way */
		1418	if (w->attr.st_nlink)
		1419	{
		1420	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1421	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1422	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1423	}
		1424	else
		1425	/* you shalt not abuse printf for puts */
		1426	puts ("wow, /etc/passwd is not there, expect problems. "
		1427	"if this is windows, they already arrived\n");
		1428	}
		1429
		1430	...
		1431	ev_stat passwd;
		1432
		1433	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1434	ev_stat_start (loop, &passwd);
		1435
		1436
1050	=head2 C<ev_idle> - when you've got nothing better to do	1437	=head2 C<ev_idle> - when you've got nothing better to do...
1051		1438
1052	Idle watchers trigger events when there are no other events are pending	1439	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	1440	priority are pending (prepare, check and other idle watchers do not
1054	as your process is busy handling sockets or timeouts (or even signals,	1441	count).
1055	imagine) it will not be triggered. But when your process is idle all idle	1442
1056	watchers are being called again and again, once per event loop iteration -	1443	That is, as long as your process is busy handling sockets or timeouts
		1444	(or even signals, imagine) of the same or higher priority it will not be
		1445	triggered. But when your process is idle (or only lower-priority watchers
		1446	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	1447	iteration - until stopped, that is, or your process receives more events
1058	busy.	1448	and becomes busy again with higher priority stuff.
1059		1449
1060	The most noteworthy effect is that as long as any idle watchers are	1450	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.	1451	active, the process will not block when waiting for new events.
1062		1452
1063	Apart from keeping your process non-blocking (which is a useful	1453	Apart from keeping your process non-blocking (which is a useful
…		…
1073	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1463	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1074	believe me.	1464	believe me.
1075		1465
1076	=back	1466	=back
1077		1467
1078	Example: dynamically allocate an C<ev_idle>, start it, and in the	1468	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1079	callback, free it. Alos, use no error checking, as usual.	1469	callback, free it. Also, use no error checking, as usual.
1080		1470
1081	static void	1471	static void
1082	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1472	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1083	{	1473	{
1084	free (w);	1474	free (w);
…		…
1089	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1479	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1090	ev_idle_init (idle_watcher, idle_cb);	1480	ev_idle_init (idle_watcher, idle_cb);
1091	ev_idle_start (loop, idle_cb);	1481	ev_idle_start (loop, idle_cb);
1092		1482
1093		1483
1094	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	1484	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1095		1485
1096	Prepare and check watchers are usually (but not always) used in tandem:	1486	Prepare and check watchers are usually (but not always) used in tandem:
1097	prepare watchers get invoked before the process blocks and check watchers	1487	prepare watchers get invoked before the process blocks and check watchers
1098	afterwards.	1488	afterwards.
1099		1489
		1490	You I<must not> call C<ev_loop> or similar functions that enter
		1491	the current event loop from either C<ev_prepare> or C<ev_check>
		1492	watchers. Other loops than the current one are fine, however. The
		1493	rationale behind this is that you do not need to check for recursion in
		1494	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
		1495	C<ev_check> so if you have one watcher of each kind they will always be
		1496	called in pairs bracketing the blocking call.
		1497
1100	Their main purpose is to integrate other event mechanisms into libev and	1498	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	1499	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	1500	variable changes, implement your own watchers, integrate net-snmp or a
1103	coroutine library and lots more.	1501	coroutine library and lots more. They are also occasionally useful if
		1502	you cache some data and want to flush it before blocking (for example,
		1503	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
		1504	watcher).
1104		1505
1105	This is done by examining in each prepare call which file descriptors need	1506	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	1507	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	1508	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	1509	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	1519	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	1520	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	1521	loop from blocking if lower-priority coroutines are active, thus mapping
1121	low-priority coroutines to idle/background tasks).	1522	low-priority coroutines to idle/background tasks).
1122		1523
		1524	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1525	priority, to ensure that they are being run before any other watchers
		1526	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1527	too) should not activate ("feed") events into libev. While libev fully
		1528	supports this, they will be called before other C<ev_check> watchers did
		1529	their job. As C<ev_check> watchers are often used to embed other event
		1530	loops those other event loops might be in an unusable state until their
		1531	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1532	others).
		1533
1123	=over 4	1534	=over 4
1124		1535
1125	=item ev_prepare_init (ev_prepare *, callback)	1536	=item ev_prepare_init (ev_prepare *, callback)
1126		1537
1127	=item ev_check_init (ev_check *, callback)	1538	=item ev_check_init (ev_check *, callback)
…		…
1130	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1541	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.	1542	macros, but using them is utterly, utterly and completely pointless.
1132		1543
1133	=back	1544	=back
1134		1545
1135	Example: *TODO*.	1546	There are a number of principal ways to embed other event loops or modules
		1547	into libev. Here are some ideas on how to include libadns into libev
		1548	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1549	use for an actually working example. Another Perl module named C<EV::Glib>
		1550	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1551	into the Glib event loop).
1136		1552
		1553	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
		1554	and in a check watcher, destroy them and call into libadns. What follows
		1555	is pseudo-code only of course. This requires you to either use a low
		1556	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1557	the callbacks for the IO/timeout watchers might not have been called yet.
1137		1558
		1559	static ev_io iow [nfd];
		1560	static ev_timer tw;
		1561
		1562	static void
		1563	io_cb (ev_loop *loop, ev_io *w, int revents)
		1564	{
		1565	}
		1566
		1567	// create io watchers for each fd and a timer before blocking
		1568	static void
		1569	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
		1570	{
		1571	int timeout = 3600000;
		1572	struct pollfd fds [nfd];
		1573	// actual code will need to loop here and realloc etc.
		1574	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1575
		1576	/* the callback is illegal, but won't be called as we stop during check */
		1577	ev_timer_init (&tw, 0, timeout * 1e-3);
		1578	ev_timer_start (loop, &tw);
		1579
		1580	// create one ev_io per pollfd
		1581	for (int i = 0; i < nfd; ++i)
		1582	{
		1583	ev_io_init (iow + i, io_cb, fds [i].fd,
		1584	((fds [i].events & POLLIN ? EV_READ : 0)
		1585	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1586
		1587	fds [i].revents = 0;
		1588	ev_io_start (loop, iow + i);
		1589	}
		1590	}
		1591
		1592	// stop all watchers after blocking
		1593	static void
		1594	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
		1595	{
		1596	ev_timer_stop (loop, &tw);
		1597
		1598	for (int i = 0; i < nfd; ++i)
		1599	{
		1600	// set the relevant poll flags
		1601	// could also call adns_processreadable etc. here
		1602	struct pollfd *fd = fds + i;
		1603	int revents = ev_clear_pending (iow + i);
		1604	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1605	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1606
		1607	// now stop the watcher
		1608	ev_io_stop (loop, iow + i);
		1609	}
		1610
		1611	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1612	}
		1613
		1614	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1615	in the prepare watcher and would dispose of the check watcher.
		1616
		1617	Method 3: If the module to be embedded supports explicit event
		1618	notification (adns does), you can also make use of the actual watcher
		1619	callbacks, and only destroy/create the watchers in the prepare watcher.
		1620
		1621	static void
		1622	timer_cb (EV_P_ ev_timer *w, int revents)
		1623	{
		1624	adns_state ads = (adns_state)w->data;
		1625	update_now (EV_A);
		1626
		1627	adns_processtimeouts (ads, &tv_now);
		1628	}
		1629
		1630	static void
		1631	io_cb (EV_P_ ev_io *w, int revents)
		1632	{
		1633	adns_state ads = (adns_state)w->data;
		1634	update_now (EV_A);
		1635
		1636	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1637	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1638	}
		1639
		1640	// do not ever call adns_afterpoll
		1641
		1642	Method 4: Do not use a prepare or check watcher because the module you
		1643	want to embed is too inflexible to support it. Instead, youc na override
		1644	their poll function. The drawback with this solution is that the main
		1645	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1646	this.
		1647
		1648	static gint
		1649	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1650	{
		1651	int got_events = 0;
		1652
		1653	for (n = 0; n < nfds; ++n)
		1654	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1655
		1656	if (timeout >= 0)
		1657	// create/start timer
		1658
		1659	// poll
		1660	ev_loop (EV_A_ 0);
		1661
		1662	// stop timer again
		1663	if (timeout >= 0)
		1664	ev_timer_stop (EV_A_ &to);
		1665
		1666	// stop io watchers again - their callbacks should have set
		1667	for (n = 0; n < nfds; ++n)
		1668	ev_io_stop (EV_A_ iow [n]);
		1669
		1670	return got_events;
		1671	}
		1672
		1673
1138	=head2 C<ev_embed> - when one backend isn't enough	1674	=head2 C<ev_embed> - when one backend isn't enough...
1139		1675
1140	This is a rather advanced watcher type that lets you embed one event loop	1676	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	1677	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	1678	loop, other types of watchers might be handled in a delayed or incorrect
1143	fashion and must not be used).	1679	fashion and must not be used).
…		…
1221		1757
1222	Make a single, non-blocking sweep over the embedded loop. This works	1758	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	1759	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1224	apropriate way for embedded loops.	1760	apropriate way for embedded loops.
1225		1761
		1762	=item struct ev_loop *loop [read-only]
		1763
		1764	The embedded event loop.
		1765
		1766	=back
		1767
		1768
		1769	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1770
		1771	Fork watchers are called when a C<fork ()> was detected (usually because
		1772	whoever is a good citizen cared to tell libev about it by calling
		1773	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1774	event loop blocks next and before C<ev_check> watchers are being called,
		1775	and only in the child after the fork. If whoever good citizen calling
		1776	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1777	handlers will be invoked, too, of course.
		1778
		1779	=over 4
		1780
		1781	=item ev_fork_init (ev_signal *, callback)
		1782
		1783	Initialises and configures the fork watcher - it has no parameters of any
		1784	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1785	believe me.
		1786
1226	=back	1787	=back
1227		1788
1228		1789
1229	=head1 OTHER FUNCTIONS	1790	=head1 OTHER FUNCTIONS
1230		1791
…		…
1318		1879
1319	To use it,	1880	To use it,
1320		1881
1321	#include <ev++.h>	1882	#include <ev++.h>
1322		1883
1323	(it is not installed by default). This automatically includes F<ev.h>	1884	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	1885	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.	1886	put into the C<ev> namespace. It should support all the same embedding
		1887	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1326		1888
1327	It should support all the same embedding options as F<ev.h>, most notably	1889	Care has been taken to keep the overhead low. The only data member the C++
1328	C<EV_MULTIPLICITY>.	1890	classes add (compared to plain C-style watchers) is the event loop pointer
		1891	that the watcher is associated with (or no additional members at all if
		1892	you disable C<EV_MULTIPLICITY> when embedding libev).
		1893
		1894	Currently, functions, and static and non-static member functions can be
		1895	used as callbacks. Other types should be easy to add as long as they only
		1896	need one additional pointer for context. If you need support for other
		1897	types of functors please contact the author (preferably after implementing
		1898	it).
1329		1899
1330	Here is a list of things available in the C<ev> namespace:	1900	Here is a list of things available in the C<ev> namespace:
1331		1901
1332	=over 4	1902	=over 4
1333		1903
…		…
1349		1919
1350	All of those classes have these methods:	1920	All of those classes have these methods:
1351		1921
1352	=over 4	1922	=over 4
1353		1923
1354	=item ev::TYPE::TYPE (object *, object::method *)	1924	=item ev::TYPE::TYPE ()
1355		1925
1356	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)	1926	=item ev::TYPE::TYPE (struct ev_loop *)
1357		1927
1358	=item ev::TYPE::~TYPE	1928	=item ev::TYPE::~TYPE
1359		1929
1360	The constructor takes a pointer to an object and a method pointer to	1930	The constructor (optionally) takes an event loop to associate the watcher
1361	the event handler callback to call in this class. The constructor calls	1931	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	1932
1363	before starting it. If you do not specify a loop then the constructor	1933	The constructor calls C<ev_init> for you, which means you have to call the
1364	automatically associates the default loop with this watcher.	1934	C<set> method before starting it.
		1935
		1936	It will not set a callback, however: You have to call the templated C<set>
		1937	method to set a callback before you can start the watcher.
		1938
		1939	(The reason why you have to use a method is a limitation in C++ which does
		1940	not allow explicit template arguments for constructors).
1365		1941
1366	The destructor automatically stops the watcher if it is active.	1942	The destructor automatically stops the watcher if it is active.
		1943
		1944	=item w->set<class, &class::method> (object *)
		1945
		1946	This method sets the callback method to call. The method has to have a
		1947	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1948	first argument and the C<revents> as second. The object must be given as
		1949	parameter and is stored in the C<data> member of the watcher.
		1950
		1951	This method synthesizes efficient thunking code to call your method from
		1952	the C callback that libev requires. If your compiler can inline your
		1953	callback (i.e. it is visible to it at the place of the C<set> call and
		1954	your compiler is good :), then the method will be fully inlined into the
		1955	thunking function, making it as fast as a direct C callback.
		1956
		1957	Example: simple class declaration and watcher initialisation
		1958
		1959	struct myclass
		1960	{
		1961	void io_cb (ev::io &w, int revents) { }
		1962	}
		1963
		1964	myclass obj;
		1965	ev::io iow;
		1966	iow.set <myclass, &myclass::io_cb> (&obj);
		1967
		1968	=item w->set<function> (void *data = 0)
		1969
		1970	Also sets a callback, but uses a static method or plain function as
		1971	callback. The optional C<data> argument will be stored in the watcher's
		1972	C<data> member and is free for you to use.
		1973
		1974	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		1975
		1976	See the method-C<set> above for more details.
		1977
		1978	Example:
		1979
		1980	static void io_cb (ev::io &w, int revents) { }
		1981	iow.set <io_cb> ();
1367		1982
1368	=item w->set (struct ev_loop *)	1983	=item w->set (struct ev_loop *)
1369		1984
1370	Associates a different C<struct ev_loop> with this watcher. You can only	1985	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).	1986	do this when the watcher is inactive (and not pending either).
1372		1987
1373	=item w->set ([args])	1988	=item w->set ([args])
1374		1989
1375	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1990	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	1991	called at least once. Unlike the C counterpart, an active watcher gets
1377	automatically stopped and restarted.	1992	automatically stopped and restarted when reconfiguring it with this
		1993	method.
1378		1994
1379	=item w->start ()	1995	=item w->start ()
1380		1996
1381	Starts the watcher. Note that there is no C<loop> argument as the	1997	Starts the watcher. Note that there is no C<loop> argument, as the
1382	constructor already takes the loop.	1998	constructor already stores the event loop.
1383		1999
1384	=item w->stop ()	2000	=item w->stop ()
1385		2001
1386	Stops the watcher if it is active. Again, no C<loop> argument.	2002	Stops the watcher if it is active. Again, no C<loop> argument.
1387		2003
…		…
1392		2008
1393	=item w->sweep () C<ev::embed> only	2009	=item w->sweep () C<ev::embed> only
1394		2010
1395	Invokes C<ev_embed_sweep>.	2011	Invokes C<ev_embed_sweep>.
1396		2012
		2013	=item w->update () C<ev::stat> only
		2014
		2015	Invokes C<ev_stat_stat>.
		2016
1397	=back	2017	=back
1398		2018
1399	=back	2019	=back
1400		2020
1401	Example: Define a class with an IO and idle watcher, start one of them in	2021	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1408		2028
1409	myclass ();	2029	myclass ();
1410	}	2030	}
1411		2031
1412	myclass::myclass (int fd)	2032	myclass::myclass (int fd)
1413	: io (this, &myclass::io_cb),
1414	idle (this, &myclass::idle_cb)
1415	{	2033	{
		2034	io .set <myclass, &myclass::io_cb > (this);
		2035	idle.set <myclass, &myclass::idle_cb> (this);
		2036
1416	io.start (fd, ev::READ);	2037	io.start (fd, ev::READ);
1417	}	2038	}
		2039
		2040
		2041	=head1 MACRO MAGIC
		2042
		2043	Libev can be compiled with a variety of options, the most fundemantal is
		2044	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
		2045	callbacks have an initial C<struct ev_loop *> argument.
		2046
		2047	To make it easier to write programs that cope with either variant, the
		2048	following macros are defined:
		2049
		2050	=over 4
		2051
		2052	=item C<EV_A>, C<EV_A_>
		2053
		2054	This provides the loop I<argument> for functions, if one is required ("ev
		2055	loop argument"). The C<EV_A> form is used when this is the sole argument,
		2056	C<EV_A_> is used when other arguments are following. Example:
		2057
		2058	ev_unref (EV_A);
		2059	ev_timer_add (EV_A_ watcher);
		2060	ev_loop (EV_A_ 0);
		2061
		2062	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		2063	which is often provided by the following macro.
		2064
		2065	=item C<EV_P>, C<EV_P_>
		2066
		2067	This provides the loop I<parameter> for functions, if one is required ("ev
		2068	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		2069	C<EV_P_> is used when other parameters are following. Example:
		2070
		2071	// this is how ev_unref is being declared
		2072	static void ev_unref (EV_P);
		2073
		2074	// this is how you can declare your typical callback
		2075	static void cb (EV_P_ ev_timer *w, int revents)
		2076
		2077	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		2078	suitable for use with C<EV_A>.
		2079
		2080	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		2081
		2082	Similar to the other two macros, this gives you the value of the default
		2083	loop, if multiple loops are supported ("ev loop default").
		2084
		2085	=back
		2086
		2087	Example: Declare and initialise a check watcher, utilising the above
		2088	macros so it will work regardless of whether multiple loops are supported
		2089	or not.
		2090
		2091	static void
		2092	check_cb (EV_P_ ev_timer *w, int revents)
		2093	{
		2094	ev_check_stop (EV_A_ w);
		2095	}
		2096
		2097	ev_check check;
		2098	ev_check_init (&check, check_cb);
		2099	ev_check_start (EV_DEFAULT_ &check);
		2100	ev_loop (EV_DEFAULT_ 0);
1418		2101
1419	=head1 EMBEDDING	2102	=head1 EMBEDDING
1420		2103
1421	Libev can (and often is) directly embedded into host	2104	Libev can (and often is) directly embedded into host
1422	applications. Examples of applications that embed it include the Deliantra	2105	applications. Examples of applications that embed it include the Deliantra
…		…
1462	ev_vars.h	2145	ev_vars.h
1463	ev_wrap.h	2146	ev_wrap.h
1464		2147
1465	ev_win32.c required on win32 platforms only	2148	ev_win32.c required on win32 platforms only
1466		2149
1467	ev_select.c only when select backend is enabled (which is is by default)	2150	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)	2151	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)	2152	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)	2153	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)	2154	ev_port.c only when the solaris port backend is enabled (disabled by default)
1472		2155
1473	F<ev.c> includes the backend files directly when enabled, so you only need	2156	F<ev.c> includes the backend files directly when enabled, so you only need
1474	to compile a single file.	2157	to compile this single file.
1475		2158
1476	=head3 LIBEVENT COMPATIBILITY API	2159	=head3 LIBEVENT COMPATIBILITY API
1477		2160
1478	To include the libevent compatibility API, also include:	2161	To include the libevent compatibility API, also include:
1479		2162
…		…
1492		2175
1493	=head3 AUTOCONF SUPPORT	2176	=head3 AUTOCONF SUPPORT
1494		2177
1495	Instead of using C<EV_STANDALONE=1> and providing your config in	2178	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	2179	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	2180	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
1498	F<config.h> and configure itself accordingly.	2181	include F<config.h> and configure itself accordingly.
1499		2182
1500	For this of course you need the m4 file:	2183	For this of course you need the m4 file:
1501		2184
1502	libev.m4	2185	libev.m4
1503		2186
…		…
1583	otherwise another method will be used as fallback. This is the preferred	2266	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	2267	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	2268	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	2269	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	2270	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	2271	out whether kqueue supports your type of fd properly and use an embedded
1589	kqueue loop.	2272	kqueue loop.
1590		2273
1591	=item EV_USE_PORT	2274	=item EV_USE_PORT
1592		2275
1593	If defined to be C<1>, libev will compile in support for the Solaris	2276	If defined to be C<1>, libev will compile in support for the Solaris
…		…
1596	backend for Solaris 10 systems.	2279	backend for Solaris 10 systems.
1597		2280
1598	=item EV_USE_DEVPOLL	2281	=item EV_USE_DEVPOLL
1599		2282
1600	reserved for future expansion, works like the USE symbols above.	2283	reserved for future expansion, works like the USE symbols above.
		2284
		2285	=item EV_USE_INOTIFY
		2286
		2287	If defined to be C<1>, libev will compile in support for the Linux inotify
		2288	interface to speed up C<ev_stat> watchers. Its actual availability will
		2289	be detected at runtime.
1601		2290
1602	=item EV_H	2291	=item EV_H
1603		2292
1604	The name of the F<ev.h> header file used to include it. The default if	2293	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	2294	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	2318	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	2319	additional independent event loops. Otherwise there will be no support
1631	for multiple event loops and there is no first event loop pointer	2320	for multiple event loops and there is no first event loop pointer
1632	argument. Instead, all functions act on the single default loop.	2321	argument. Instead, all functions act on the single default loop.
1633		2322
		2323	=item EV_MINPRI
		2324
		2325	=item EV_MAXPRI
		2326
		2327	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2328	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2329	provide for more priorities by overriding those symbols (usually defined
		2330	to be C<-2> and C<2>, respectively).
		2331
		2332	When doing priority-based operations, libev usually has to linearly search
		2333	all the priorities, so having many of them (hundreds) uses a lot of space
		2334	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2335	fine.
		2336
		2337	If your embedding app does not need any priorities, defining these both to
		2338	C<0> will save some memory and cpu.
		2339
1634	=item EV_PERIODICS	2340	=item EV_PERIODIC_ENABLE
1635		2341
1636	If undefined or defined to be C<1>, then periodic timers are supported,	2342	If undefined or defined to be C<1>, then periodic timers are supported. If
1637	otherwise not. This saves a few kb of code.	2343	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2344	code.
		2345
		2346	=item EV_IDLE_ENABLE
		2347
		2348	If undefined or defined to be C<1>, then idle watchers are supported. If
		2349	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2350	code.
		2351
		2352	=item EV_EMBED_ENABLE
		2353
		2354	If undefined or defined to be C<1>, then embed watchers are supported. If
		2355	defined to be C<0>, then they are not.
		2356
		2357	=item EV_STAT_ENABLE
		2358
		2359	If undefined or defined to be C<1>, then stat watchers are supported. If
		2360	defined to be C<0>, then they are not.
		2361
		2362	=item EV_FORK_ENABLE
		2363
		2364	If undefined or defined to be C<1>, then fork watchers are supported. If
		2365	defined to be C<0>, then they are not.
		2366
		2367	=item EV_MINIMAL
		2368
		2369	If you need to shave off some kilobytes of code at the expense of some
		2370	speed, define this symbol to C<1>. Currently only used for gcc to override
		2371	some inlining decisions, saves roughly 30% codesize of amd64.
		2372
		2373	=item EV_PID_HASHSIZE
		2374
		2375	C<ev_child> watchers use a small hash table to distribute workload by
		2376	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2377	than enough. If you need to manage thousands of children you might want to
		2378	increase this value (I<must> be a power of two).
		2379
		2380	=item EV_INOTIFY_HASHSIZE
		2381
		2382	C<ev_staz> watchers use a small hash table to distribute workload by
		2383	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2384	usually more than enough. If you need to manage thousands of C<ev_stat>
		2385	watchers you might want to increase this value (I<must> be a power of
		2386	two).
1638		2387
1639	=item EV_COMMON	2388	=item EV_COMMON
1640		2389
1641	By default, all watchers have a C<void *data> member. By redefining	2390	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	2391	this macro to a something else you can include more and other types of
…		…
1647		2396
1648	#define EV_COMMON \	2397	#define EV_COMMON \
1649	SV *self; /* contains this struct */ \	2398	SV *self; /* contains this struct */ \
1650	SV *cb_sv, *fh /* note no trailing ";" */	2399	SV *cb_sv, *fh /* note no trailing ";" */
1651		2400
1652	=item EV_CB_DECLARE(type)	2401	=item EV_CB_DECLARE (type)
1653		2402
1654	=item EV_CB_INVOKE(watcher,revents)	2403	=item EV_CB_INVOKE (watcher, revents)
1655		2404
1656	=item ev_set_cb(ev,cb)	2405	=item ev_set_cb (ev, cb)
1657		2406
1658	Can be used to change the callback member declaration in each watcher,	2407	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	2408	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	2409	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	2410	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	2411	avoid the C<struct ev_loop *> as first argument in all cases, or to use
1663	calls instead of plain function calls in C++.	2412	method calls instead of plain function calls in C++.
1664		2413
1665	=head2 EXAMPLES	2414	=head2 EXAMPLES
1666		2415
1667	For a real-world example of a program the includes libev	2416	For a real-world example of a program the includes libev
1668	verbatim, you can have a look at the EV perl module	2417	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	2420	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	2421	will be compiled. It is pretty complex because it provides its own header
1673	file.	2422	file.
1674		2423
1675	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2424	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:	2425	that everybody includes and which overrides some configure choices:
1677		2426
		2427	#define EV_MINIMAL 1
1678	#define EV_USE_POLL 0	2428	#define EV_USE_POLL 0
1679	#define EV_MULTIPLICITY 0	2429	#define EV_MULTIPLICITY 0
1680	#define EV_PERIODICS 0	2430	#define EV_PERIODIC_ENABLE 0
		2431	#define EV_STAT_ENABLE 0
		2432	#define EV_FORK_ENABLE 0
1681	#define EV_CONFIG_H <config.h>	2433	#define EV_CONFIG_H <config.h>
		2434	#define EV_MINPRI 0
		2435	#define EV_MAXPRI 0
1682		2436
1683	#include "ev++.h"	2437	#include "ev++.h"
1684		2438
1685	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2439	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1686		2440
1687	#include "rxvttoolkit.h"	2441	#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"	2442	#include "ev.c"
		2443
		2444
		2445	=head1 COMPLEXITIES
		2446
		2447	In this section the complexities of (many of) the algorithms used inside
		2448	libev will be explained. For complexity discussions about backends see the
		2449	documentation for C<ev_default_init>.
		2450
		2451	All of the following are about amortised time: If an array needs to be
		2452	extended, libev needs to realloc and move the whole array, but this
		2453	happens asymptotically never with higher number of elements, so O(1) might
		2454	mean it might do a lengthy realloc operation in rare cases, but on average
		2455	it is much faster and asymptotically approaches constant time.
		2456
		2457	=over 4
		2458
		2459	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
		2460
		2461	This means that, when you have a watcher that triggers in one hour and
		2462	there are 100 watchers that would trigger before that then inserting will
		2463	have to skip those 100 watchers.
		2464
		2465	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
		2466
		2467	That means that for changing a timer costs less than removing/adding them
		2468	as only the relative motion in the event queue has to be paid for.
		2469
		2470	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
		2471
		2472	These just add the watcher into an array or at the head of a list.
		2473	=item Stopping check/prepare/idle watchers: O(1)
		2474
		2475	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2476
		2477	These watchers are stored in lists then need to be walked to find the
		2478	correct watcher to remove. The lists are usually short (you don't usually
		2479	have many watchers waiting for the same fd or signal).
		2480
		2481	=item Finding the next timer per loop iteration: O(1)
		2482
		2483	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		2484
		2485	A change means an I/O watcher gets started or stopped, which requires
		2486	libev to recalculate its status (and possibly tell the kernel).
		2487
		2488	=item Activating one watcher: O(1)
		2489
		2490	=item Priority handling: O(number_of_priorities)
		2491
		2492	Priorities are implemented by allocating some space for each
		2493	priority. When doing priority-based operations, libev usually has to
		2494	linearly search all the priorities.
		2495
		2496	=back
1693		2497
1694		2498
1695	=head1 AUTHOR	2499	=head1 AUTHOR
1696		2500
1697	Marc Lehmann <libev@schmorp.de>.	2501	Marc Lehmann <libev@schmorp.de>.

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