[ViewVC] Diff of: cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.40 by root, Sat Nov 24 10:15:16 2007 UTC vs.
Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC

…		…
3	libev - a high performance full-featured event loop written in C	3	libev - a high performance full-featured event loop written in C
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
		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	}
8		50
9	=head1 DESCRIPTION	51	=head1 DESCRIPTION
10		52
11	Libev is an event loop: you register interest in certain events (such as a	53	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	54	file descriptor being readable or a timeout occuring), and it will manage
…		…
21	details of the event, and then hand it over to libev by I<starting> the	63	details of the event, and then hand it over to libev by I<starting> the
22	watcher.	64	watcher.
23		65
24	=head1 FEATURES	66	=head1 FEATURES
25		67
26	Libev supports select, poll, the linux-specific epoll and the bsd-specific	68	Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the
27	kqueue mechanisms for file descriptor events, relative timers, absolute	69	bsd-specific C<kqueue> and the solaris-specific event port mechanisms
28	timers with customised rescheduling, signal events, process status change	70	for file descriptor events (C<ev_io>), relative timers (C<ev_timer>),
29	events (related to SIGCHLD), and event watchers dealing with the event	71	absolute timers with customised rescheduling (C<ev_periodic>), synchronous
30	loop mechanism itself (idle, prepare and check watchers). It also is quite	72	signals (C<ev_signal>), process status change events (C<ev_child>), and
		73	event watchers dealing with the event loop mechanism itself (C<ev_idle>,
		74	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
		75	file watchers (C<ev_stat>) and even limited support for fork events
		76	(C<ev_fork>).
		77
		78	It also is quite fast (see this
31	fast (see this L<benchmark\|http://libev.schmorp.de/bench.html> comparing	79	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent
32	it to libevent for example).	80	for example).
33		81
34	=head1 CONVENTIONS	82	=head1 CONVENTIONS
35		83
36	Libev is very configurable. In this manual the default configuration	84	Libev is very configurable. In this manual the default configuration will
37	will be described, which supports multiple event loops. For more info	85	be described, which supports multiple event loops. For more info about
38	about various configuration options please have a look at the file	86	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	87	this manual. If libev was configured without support for multiple event
40	support for multiple event loops, then all functions taking an initial	88	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 *>)	89	(which is always of type C<struct ev_loop *>) will not have this argument.
42	will not have this argument.
43		90
44	=head1 TIME REPRESENTATION	91	=head1 TIME REPRESENTATION
45		92
46	Libev represents time as a single floating point number, representing the	93	Libev represents time as a single floating point number, representing the
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	94	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	95	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	96	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	97	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	98	it, you should treat it as such.
52		99
53
54	=head1 GLOBAL FUNCTIONS	100	=head1 GLOBAL FUNCTIONS
55		101
56	These functions can be called anytime, even before initialising the	102	These functions can be called anytime, even before initialising the
57	library in any way.	103	library in any way.
58		104
…		…
77	Usually, it's a good idea to terminate if the major versions mismatch,	123	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	124	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	125	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	126	not a problem.
81		127
82	Example: make sure we haven't accidentally been linked against the wrong	128	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	129	version.
84		130
85	assert (("libev version mismatch",	131	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	132	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	133	&& ev_version_minor () >= EV_VERSION_MINOR));
88		134
…		…
116	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	162	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
117	recommended ones.	163	recommended ones.
118		164
119	See the description of C<ev_embed> watchers for more info.	165	See the description of C<ev_embed> watchers for more info.
120		166
121	=item ev_set_allocator (void (cb)(void *ptr, long size))	167	=item ev_set_allocator (void (cb)(void *ptr, size_t size))
122		168
123	Sets the allocation function to use (the prototype is similar to the	169	Sets the allocation function to use (the prototype and semantics are
124	realloc C function, the semantics are identical). It is used to allocate	170	identical to the realloc C function). It is used to allocate and free
125	and free memory (no surprises here). If it returns zero when memory	171	memory (no surprises here). If it returns zero when memory needs to be
126	needs to be allocated, the library might abort or take some potentially	172	allocated, the library might abort or take some potentially destructive
127	destructive action. The default is your system realloc function.	173	action. The default is your system realloc function.
128		174
129	You could override this function in high-availability programs to, say,	175	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,	176	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.	177	or even to sleep a while and retry until some memory is available.
132		178
133	Example: replace the libev allocator with one that waits a bit and then	179	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	180	retries).
135		181
136	static void *	182	static void *
137	persistent_realloc (void *ptr, long size)	183	persistent_realloc (void *ptr, size_t size)
138	{	184	{
139	for (;;)	185	for (;;)
140	{	186	{
141	void *newptr = realloc (ptr, size);	187	void *newptr = realloc (ptr, size);
142		188
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	204	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	205	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	206	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	207	(such as abort).
162		208
163	Example: do the same thing as libev does internally:	209	Example: This is basically the same thing that libev does internally, too.
164		210
165	static void	211	static void
166	fatal_error (const char *msg)	212	fatal_error (const char *msg)
167	{	213	{
168	perror (msg);	214	perror (msg);
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	360	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	361	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	362	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).	363	undefined behaviour (or a failed assertion if assertions are enabled).
318		364
319	Example: try to create a event loop that uses epoll and nothing else.	365	Example: Try to create a event loop that uses epoll and nothing else.
320		366
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	367	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
322	if (!epoller)	368	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	369	fatal ("no epoll found here, maybe it hides under your chair");
324		370
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	469	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	470	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	471	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	472	were used, return, otherwise continue with step *.
427		473
428	Example: queue some jobs and then loop until no events are outsanding	474	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	475	anymore.
430		476
431	... queue jobs here, make sure they register event watchers as long	477	... 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..)	478	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	479	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	499	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	500	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	501	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>.	502	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		503
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	504	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	505	running when nothing else is active.
460		506
461	struct dv_signal exitsig;	507	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	508	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	509	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	510	evf_unref (loop);
465		511
466	Example: for some weird reason, unregister the above signal handler again.	512	Example: For some weird reason, unregister the above signal handler again.
467		513
468	ev_ref (myloop);	514	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	515	ev_signal_stop (loop, &exitsig);
470		516
471	=back	517	=back
		518
472		519
473	=head1 ANATOMY OF A WATCHER	520	=head1 ANATOMY OF A WATCHER
474		521
475	A watcher is a structure that you create and register to record your	522	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	523	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.	590	The signal specified in the C<ev_signal> watcher has been received by a thread.
544		591
545	=item C<EV_CHILD>	592	=item C<EV_CHILD>
546		593
547	The pid specified in the C<ev_child> watcher has received a status change.	594	The pid specified in the C<ev_child> watcher has received a status change.
		595
		596	=item C<EV_STAT>
		597
		598	The path specified in the C<ev_stat> watcher changed its attributes somehow.
548		599
549	=item C<EV_IDLE>	600	=item C<EV_IDLE>
550		601
551	The C<ev_idle> watcher has determined that you have nothing better to do.	602	The C<ev_idle> watcher has determined that you have nothing better to do.
552		603
…		…
560	received events. Callbacks of both watcher types can start and stop as	611	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	612	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	613	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
563	C<ev_loop> from blocking).	614	C<ev_loop> from blocking).
564		615
		616	=item C<EV_EMBED>
		617
		618	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		619
		620	=item C<EV_FORK>
		621
		622	The event loop has been resumed in the child process after fork (see
		623	C<ev_fork>).
		624
565	=item C<EV_ERROR>	625	=item C<EV_ERROR>
566		626
567	An unspecified error has occured, the watcher has been stopped. This might	627	An unspecified error has occured, the watcher has been stopped. This might
568	happen because the watcher could not be properly started because libev	628	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	629	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	636	with the error from read() or write(). This will not work in multithreaded
577	programs, though, so beware.	637	programs, though, so beware.
578		638
579	=back	639	=back
580		640
581	=head2 SUMMARY OF GENERIC WATCHER FUNCTIONS	641	=head2 GENERIC WATCHER FUNCTIONS
582		642
583	In the following description, C<TYPE> stands for the watcher type,	643	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.	644	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.
585		645
586	=over 4	646	=over 4
…		…
595	which rolls both calls into one.	655	which rolls both calls into one.
596		656
597	You can reinitialise a watcher at any time as long as it has been stopped	657	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.	658	(or never started) and there are no pending events outstanding.
599		659
600	The callbakc is always of type C<void ()(ev_loop loop, ev_TYPE *watcher,	660	The callback is always of type C<void ()(ev_loop loop, ev_TYPE *watcher,
601	int revents)>.	661	int revents)>.
602		662
603	=item C<ev_TYPE_set> (ev_TYPE *, [args])	663	=item C<ev_TYPE_set> (ev_TYPE *, [args])
604		664
605	This macro initialises the type-specific parts of a watcher. You need to	665	This macro initialises the type-specific parts of a watcher. You need to
…		…
688		748
689		749
690	=head1 WATCHER TYPES	750	=head1 WATCHER TYPES
691		751
692	This section describes each watcher in detail, but will not repeat	752	This section describes each watcher in detail, but will not repeat
693	information given in the last section.	753	information given in the last section. Any initialisation/set macros,
		754	functions and members specific to the watcher type are explained.
694		755
		756	Members are additionally marked with either I<[read-only]>, meaning that,
		757	while the watcher is active, you can look at the member and expect some
		758	sensible content, but you must not modify it (you can modify it while the
		759	watcher is stopped to your hearts content), or I<[read-write]>, which
		760	means you can expect it to have some sensible content while the watcher
		761	is active, but you can also modify it. Modifying it may not do something
		762	sensible or take immediate effect (or do anything at all), but libev will
		763	not crash or malfunction in any way.
695		764
		765
696	=head2 C<ev_io> - is this file descriptor readable or writable	766	=head2 C<ev_io> - is this file descriptor readable or writable?
697		767
698	I/O watchers check whether a file descriptor is readable or writable	768	I/O watchers check whether a file descriptor is readable or writable
699	in each iteration of the event loop (This behaviour is called	769	in each iteration of the event loop, or, more precisely, when reading
700	level-triggering because you keep receiving events as long as the	770	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	771	some data. This behaviour is called level-triggering because you keep
702	act on the event and neither want to receive future events).	772	receiving events as long as the condition persists. Remember you can stop
		773	the watcher if you don't want to act on the event and neither want to
		774	receive future events.
703		775
704	In general you can register as many read and/or write event watchers per	776	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	777	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	778	descriptors to non-blocking mode is also usually a good idea (but not
707	required if you know what you are doing).	779	required if you know what you are doing).
708		780
709	You have to be careful with dup'ed file descriptors, though. Some backends	781	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	782	(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	783	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	784	to the same underlying file/socket/etc. description (that is, they share
713	the same underlying "file open").	785	the same underlying "file open").
714		786
715	If you must do this, then force the use of a known-to-be-good backend	787	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	788	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
717	C<EVBACKEND_POLL>).	789	C<EVBACKEND_POLL>).
718		790
		791	Another thing you have to watch out for is that it is quite easy to
		792	receive "spurious" readyness notifications, that is your callback might
		793	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
		794	because there is no data. Not only are some backends known to create a
		795	lot of those (for example solaris ports), it is very easy to get into
		796	this situation even with a relatively standard program structure. Thus
		797	it is best to always use non-blocking I/O: An extra C<read>(2) returning
		798	C<EAGAIN> is far preferable to a program hanging until some data arrives.
		799
		800	If you cannot run the fd in non-blocking mode (for example you should not
		801	play around with an Xlib connection), then you have to seperately re-test
		802	wether a file descriptor is really ready with a known-to-be good interface
		803	such as poll (fortunately in our Xlib example, Xlib already does this on
		804	its own, so its quite safe to use).
		805
719	=over 4	806	=over 4
720		807
721	=item ev_io_init (ev_io *, callback, int fd, int events)	808	=item ev_io_init (ev_io *, callback, int fd, int events)
722		809
723	=item ev_io_set (ev_io *, int fd, int events)	810	=item ev_io_set (ev_io *, int fd, int events)
724		811
725	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive	812	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 \|	813	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
727	EV_WRITE> to receive the given events.	814	C<EV_READ \| EV_WRITE> to receive the given events.
728		815
729	Please note that most of the more scalable backend mechanisms (for example	816	=item int fd [read-only]
730	epoll and solaris ports) can result in spurious readyness notifications	817
731	for file descriptors, so you practically need to use non-blocking I/O (and	818	The file descriptor being watched.
732	treat callback invocation as hint only), or retest separately with a safe	819
733	interface before doing I/O (XLib can do this), or force the use of either	820	=item int events [read-only]
734	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this	821
735	problem. Also note that it is quite easy to have your callback invoked	822	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		823
740	=back	824	=back
741		825
742	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	826	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	827	readable, but only once. Since it is likely line-buffered, you could
744	attempt to read a whole line in the callback:	828	attempt to read a whole line in the callback.
745		829
746	static void	830	static void
747	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	831	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
748	{	832	{
749	ev_io_stop (loop, w);	833	ev_io_stop (loop, w);
…		…
756	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	840	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
757	ev_io_start (loop, &stdin_readable);	841	ev_io_start (loop, &stdin_readable);
758	ev_loop (loop, 0);	842	ev_loop (loop, 0);
759		843
760		844
761	=head2 C<ev_timer> - relative and optionally recurring timeouts	845	=head2 C<ev_timer> - relative and optionally repeating timeouts
762		846
763	Timer watchers are simple relative timers that generate an event after a	847	Timer watchers are simple relative timers that generate an event after a
764	given time, and optionally repeating in regular intervals after that.	848	given time, and optionally repeating in regular intervals after that.
765		849
766	The timers are based on real time, that is, if you register an event that	850	The timers are based on real time, that is, if you register an event that
…		…
807		891
808	If the timer is repeating, either start it if necessary (with the repeat	892	If the timer is repeating, either start it if necessary (with the repeat
809	value), or reset the running timer to the repeat value.	893	value), or reset the running timer to the repeat value.
810		894
811	This sounds a bit complicated, but here is a useful and typical	895	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	896	example: Imagine you have a tcp connection and you want a so-called
813	timeout, that is, you want to be called when there have been, say, 60	897	idle timeout, that is, you want to be called when there have been,
814	seconds of inactivity on the socket. The easiest way to do this is to	898	say, 60 seconds of inactivity on the socket. The easiest way to do
815	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each	899	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling
816	time you successfully read or write some data. If you go into an idle	900	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	901	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.	902	socket, you can stop the timer, and again will automatically restart it if
		903	need be.
		904
		905	You can also ignore the C<after> value and C<ev_timer_start> altogether
		906	and only ever use the C<repeat> value:
		907
		908	ev_timer_init (timer, callback, 0., 5.);
		909	ev_timer_again (loop, timer);
		910	...
		911	timer->again = 17.;
		912	ev_timer_again (loop, timer);
		913	...
		914	timer->again = 10.;
		915	ev_timer_again (loop, timer);
		916
		917	This is more efficient then stopping/starting the timer eahc time you want
		918	to modify its timeout value.
		919
		920	=item ev_tstamp repeat [read-write]
		921
		922	The current C<repeat> value. Will be used each time the watcher times out
		923	or C<ev_timer_again> is called and determines the next timeout (if any),
		924	which is also when any modifications are taken into account.
819		925
820	=back	926	=back
821		927
822	Example: create a timer that fires after 60 seconds.	928	Example: Create a timer that fires after 60 seconds.
823		929
824	static void	930	static void
825	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	931	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
826	{	932	{
827	.. one minute over, w is actually stopped right here	933	.. one minute over, w is actually stopped right here
…		…
829		935
830	struct ev_timer mytimer;	936	struct ev_timer mytimer;
831	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	937	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
832	ev_timer_start (loop, &mytimer);	938	ev_timer_start (loop, &mytimer);
833		939
834	Example: create a timeout timer that times out after 10 seconds of	940	Example: Create a timeout timer that times out after 10 seconds of
835	inactivity.	941	inactivity.
836		942
837	static void	943	static void
838	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	944	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
839	{	945	{
…		…
848	// and in some piece of code that gets executed on any "activity":	954	// and in some piece of code that gets executed on any "activity":
849	// reset the timeout to start ticking again at 10 seconds	955	// reset the timeout to start ticking again at 10 seconds
850	ev_timer_again (&mytimer);	956	ev_timer_again (&mytimer);
851		957
852		958
853	=head2 C<ev_periodic> - to cron or not to cron	959	=head2 C<ev_periodic> - to cron or not to cron?
854		960
855	Periodic watchers are also timers of a kind, but they are very versatile	961	Periodic watchers are also timers of a kind, but they are very versatile
856	(and unfortunately a bit complex).	962	(and unfortunately a bit complex).
857		963
858	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	964	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
…		…
950	Simply stops and restarts the periodic watcher again. This is only useful	1056	Simply stops and restarts the periodic watcher again. This is only useful
951	when you changed some parameters or the reschedule callback would return	1057	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	1058	a different time than the last time it was called (e.g. in a crond like
953	program when the crontabs have changed).	1059	program when the crontabs have changed).
954		1060
		1061	=item ev_tstamp interval [read-write]
		1062
		1063	The current interval value. Can be modified any time, but changes only
		1064	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1065	called.
		1066
		1067	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
		1068
		1069	The current reschedule callback, or C<0>, if this functionality is
		1070	switched off. Can be changed any time, but changes only take effect when
		1071	the periodic timer fires or C<ev_periodic_again> is being called.
		1072
955	=back	1073	=back
956		1074
957	Example: call a callback every hour, or, more precisely, whenever the	1075	Example: Call a callback every hour, or, more precisely, whenever the
958	system clock is divisible by 3600. The callback invocation times have	1076	system clock is divisible by 3600. The callback invocation times have
959	potentially a lot of jittering, but good long-term stability.	1077	potentially a lot of jittering, but good long-term stability.
960		1078
961	static void	1079	static void
962	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1080	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
966		1084
967	struct ev_periodic hourly_tick;	1085	struct ev_periodic hourly_tick;
968	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1086	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
969	ev_periodic_start (loop, &hourly_tick);	1087	ev_periodic_start (loop, &hourly_tick);
970		1088
971	Example: the same as above, but use a reschedule callback to do it:	1089	Example: The same as above, but use a reschedule callback to do it:
972		1090
973	#include <math.h>	1091	#include <math.h>
974		1092
975	static ev_tstamp	1093	static ev_tstamp
976	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1094	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
978	return fmod (now, 3600.) + 3600.;	1096	return fmod (now, 3600.) + 3600.;
979	}	1097	}
980		1098
981	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1099	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
982		1100
983	Example: call a callback every hour, starting now:	1101	Example: Call a callback every hour, starting now:
984		1102
985	struct ev_periodic hourly_tick;	1103	struct ev_periodic hourly_tick;
986	ev_periodic_init (&hourly_tick, clock_cb,	1104	ev_periodic_init (&hourly_tick, clock_cb,
987	fmod (ev_now (loop), 3600.), 3600., 0);	1105	fmod (ev_now (loop), 3600.), 3600., 0);
988	ev_periodic_start (loop, &hourly_tick);	1106	ev_periodic_start (loop, &hourly_tick);
989		1107
990		1108
991	=head2 C<ev_signal> - signal me when a signal gets signalled	1109	=head2 C<ev_signal> - signal me when a signal gets signalled!
992		1110
993	Signal watchers will trigger an event when the process receives a specific	1111	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	1112	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	1113	will try it's best to deliver signals synchronously, i.e. as part of the
996	normal event processing, like any other event.	1114	normal event processing, like any other event.
…		…
1009	=item ev_signal_set (ev_signal *, int signum)	1127	=item ev_signal_set (ev_signal *, int signum)
1010		1128
1011	Configures the watcher to trigger on the given signal number (usually one	1129	Configures the watcher to trigger on the given signal number (usually one
1012	of the C<SIGxxx> constants).	1130	of the C<SIGxxx> constants).
1013		1131
		1132	=item int signum [read-only]
		1133
		1134	The signal the watcher watches out for.
		1135
1014	=back	1136	=back
1015		1137
1016		1138
1017	=head2 C<ev_child> - wait for pid status changes	1139	=head2 C<ev_child> - watch out for process status changes
1018		1140
1019	Child watchers trigger when your process receives a SIGCHLD in response to	1141	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).	1142	some child status changes (most typically when a child of yours dies).
1021		1143
1022	=over 4	1144	=over 4
…		…
1030	at the C<rstatus> member of the C<ev_child> watcher structure to see	1152	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	1153	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	1154	C<waitpid> documentation). The C<rpid> member contains the pid of the
1033	process causing the status change.	1155	process causing the status change.
1034		1156
		1157	=item int pid [read-only]
		1158
		1159	The process id this watcher watches out for, or C<0>, meaning any process id.
		1160
		1161	=item int rpid [read-write]
		1162
		1163	The process id that detected a status change.
		1164
		1165	=item int rstatus [read-write]
		1166
		1167	The process exit/trace status caused by C<rpid> (see your systems
		1168	C<waitpid> and C<sys/wait.h> documentation for details).
		1169
1035	=back	1170	=back
1036		1171
1037	Example: try to exit cleanly on SIGINT and SIGTERM.	1172	Example: Try to exit cleanly on SIGINT and SIGTERM.
1038		1173
1039	static void	1174	static void
1040	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1175	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1041	{	1176	{
1042	ev_unloop (loop, EVUNLOOP_ALL);	1177	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1045	struct ev_signal signal_watcher;	1180	struct ev_signal signal_watcher;
1046	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1181	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1047	ev_signal_start (loop, &sigint_cb);	1182	ev_signal_start (loop, &sigint_cb);
1048		1183
1049		1184
		1185	=head2 C<ev_stat> - did the file attributes just change?
		1186
		1187	This watches a filesystem path for attribute changes. That is, it calls
		1188	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1189	compared to the last time, invoking the callback if it did.
		1190
		1191	The path does not need to exist: changing from "path exists" to "path does
		1192	not exist" is a status change like any other. The condition "path does
		1193	not exist" is signified by the C<st_nlink> field being zero (which is
		1194	otherwise always forced to be at least one) and all the other fields of
		1195	the stat buffer having unspecified contents.
		1196
		1197	Since there is no standard to do this, the portable implementation simply
		1198	calls C<stat (2)> regulalry on the path to see if it changed somehow. You
		1199	can specify a recommended polling interval for this case. If you specify
		1200	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1201	unspecified default> value will be used (which you can expect to be around
		1202	five seconds, although this might change dynamically). Libev will also
		1203	impose a minimum interval which is currently around C<0.1>, but thats
		1204	usually overkill.
		1205
		1206	This watcher type is not meant for massive numbers of stat watchers,
		1207	as even with OS-supported change notifications, this can be
		1208	resource-intensive.
		1209
		1210	At the time of this writing, no specific OS backends are implemented, but
		1211	if demand increases, at least a kqueue and inotify backend will be added.
		1212
		1213	=over 4
		1214
		1215	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
		1216
		1217	=item ev_stat_set (ev_stat , const char path, ev_tstamp interval)
		1218
		1219	Configures the watcher to wait for status changes of the given
		1220	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1221	be detected and should normally be specified as C<0> to let libev choose
		1222	a suitable value. The memory pointed to by C<path> must point to the same
		1223	path for as long as the watcher is active.
		1224
		1225	The callback will be receive C<EV_STAT> when a change was detected,
		1226	relative to the attributes at the time the watcher was started (or the
		1227	last change was detected).
		1228
		1229	=item ev_stat_stat (ev_stat *)
		1230
		1231	Updates the stat buffer immediately with new values. If you change the
		1232	watched path in your callback, you could call this fucntion to avoid
		1233	detecting this change (while introducing a race condition). Can also be
		1234	useful simply to find out the new values.
		1235
		1236	=item ev_statdata attr [read-only]
		1237
		1238	The most-recently detected attributes of the file. Although the type is of
		1239	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1240	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1241	was some error while C<stat>ing the file.
		1242
		1243	=item ev_statdata prev [read-only]
		1244
		1245	The previous attributes of the file. The callback gets invoked whenever
		1246	C<prev> != C<attr>.
		1247
		1248	=item ev_tstamp interval [read-only]
		1249
		1250	The specified interval.
		1251
		1252	=item const char *path [read-only]
		1253
		1254	The filesystem path that is being watched.
		1255
		1256	=back
		1257
		1258	Example: Watch C</etc/passwd> for attribute changes.
		1259
		1260	static void
		1261	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1262	{
		1263	/* /etc/passwd changed in some way */
		1264	if (w->attr.st_nlink)
		1265	{
		1266	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1267	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1268	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1269	}
		1270	else
		1271	/* you shalt not abuse printf for puts */
		1272	puts ("wow, /etc/passwd is not there, expect problems. "
		1273	"if this is windows, they already arrived\n");
		1274	}
		1275
		1276	...
		1277	ev_stat passwd;
		1278
		1279	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1280	ev_stat_start (loop, &passwd);
		1281
		1282
1050	=head2 C<ev_idle> - when you've got nothing better to do	1283	=head2 C<ev_idle> - when you've got nothing better to do...
1051		1284
1052	Idle watchers trigger events when there are no other events are pending	1285	Idle watchers trigger events when there are no other events are pending
1053	(prepare, check and other idle watchers do not count). That is, as long	1286	(prepare, check and other idle watchers do not count). That is, as long
1054	as your process is busy handling sockets or timeouts (or even signals,	1287	as your process is busy handling sockets or timeouts (or even signals,
1055	imagine) it will not be triggered. But when your process is idle all idle	1288	imagine) it will not be triggered. But when your process is idle all idle
…		…
1073	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1306	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1074	believe me.	1307	believe me.
1075		1308
1076	=back	1309	=back
1077		1310
1078	Example: dynamically allocate an C<ev_idle>, start it, and in the	1311	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1079	callback, free it. Alos, use no error checking, as usual.	1312	callback, free it. Also, use no error checking, as usual.
1080		1313
1081	static void	1314	static void
1082	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1315	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1083	{	1316	{
1084	free (w);	1317	free (w);
…		…
1089	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1322	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1090	ev_idle_init (idle_watcher, idle_cb);	1323	ev_idle_init (idle_watcher, idle_cb);
1091	ev_idle_start (loop, idle_cb);	1324	ev_idle_start (loop, idle_cb);
1092		1325
1093		1326
1094	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	1327	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1095		1328
1096	Prepare and check watchers are usually (but not always) used in tandem:	1329	Prepare and check watchers are usually (but not always) used in tandem:
1097	prepare watchers get invoked before the process blocks and check watchers	1330	prepare watchers get invoked before the process blocks and check watchers
1098	afterwards.	1331	afterwards.
1099		1332
		1333	You I<must not> call C<ev_loop> or similar functions that enter
		1334	the current event loop from either C<ev_prepare> or C<ev_check>
		1335	watchers. Other loops than the current one are fine, however. The
		1336	rationale behind this is that you do not need to check for recursion in
		1337	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
		1338	C<ev_check> so if you have one watcher of each kind they will always be
		1339	called in pairs bracketing the blocking call.
		1340
1100	Their main purpose is to integrate other event mechanisms into libev and	1341	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	1342	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	1343	variable changes, implement your own watchers, integrate net-snmp or a
1103	coroutine library and lots more.	1344	coroutine library and lots more. They are also occasionally useful if
		1345	you cache some data and want to flush it before blocking (for example,
		1346	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
		1347	watcher).
1104		1348
1105	This is done by examining in each prepare call which file descriptors need	1349	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	1350	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	1351	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	1352	provide just this functionality). Then, in the check watcher you check for
…		…
1130	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1374	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.	1375	macros, but using them is utterly, utterly and completely pointless.
1132		1376
1133	=back	1377	=back
1134		1378
1135	Example: TODO.	1379	Example: To include a library such as adns, you would add IO watchers
		1380	and a timeout watcher in a prepare handler, as required by libadns, and
		1381	in a check watcher, destroy them and call into libadns. What follows is
		1382	pseudo-code only of course:
1136		1383
		1384	static ev_io iow [nfd];
		1385	static ev_timer tw;
1137		1386
		1387	static void
		1388	io_cb (ev_loop loop, ev_io w, int revents)
		1389	{
		1390	// set the relevant poll flags
		1391	// could also call adns_processreadable etc. here
		1392	struct pollfd fd = (struct pollfd )w->data;
		1393	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1394	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1395	}
		1396
		1397	// create io watchers for each fd and a timer before blocking
		1398	static void
		1399	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1400	{
		1401	int timeout = 3600000;truct pollfd fds [nfd];
		1402	// actual code will need to loop here and realloc etc.
		1403	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1404
		1405	/* the callback is illegal, but won't be called as we stop during check */
		1406	ev_timer_init (&tw, 0, timeout * 1e-3);
		1407	ev_timer_start (loop, &tw);
		1408
		1409	// create on ev_io per pollfd
		1410	for (int i = 0; i < nfd; ++i)
		1411	{
		1412	ev_io_init (iow + i, io_cb, fds [i].fd,
		1413	((fds [i].events & POLLIN ? EV_READ : 0)
		1414	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1415
		1416	fds [i].revents = 0;
		1417	iow [i].data = fds + i;
		1418	ev_io_start (loop, iow + i);
		1419	}
		1420	}
		1421
		1422	// stop all watchers after blocking
		1423	static void
		1424	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1425	{
		1426	ev_timer_stop (loop, &tw);
		1427
		1428	for (int i = 0; i < nfd; ++i)
		1429	ev_io_stop (loop, iow + i);
		1430
		1431	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1432	}
		1433
		1434
1138	=head2 C<ev_embed> - when one backend isn't enough	1435	=head2 C<ev_embed> - when one backend isn't enough...
1139		1436
1140	This is a rather advanced watcher type that lets you embed one event loop	1437	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	1438	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	1439	loop, other types of watchers might be handled in a delayed or incorrect
1143	fashion and must not be used).	1440	fashion and must not be used).
…		…
1221		1518
1222	Make a single, non-blocking sweep over the embedded loop. This works	1519	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	1520	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1224	apropriate way for embedded loops.	1521	apropriate way for embedded loops.
1225		1522
		1523	=item struct ev_loop *loop [read-only]
		1524
		1525	The embedded event loop.
		1526
		1527	=back
		1528
		1529
		1530	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1531
		1532	Fork watchers are called when a C<fork ()> was detected (usually because
		1533	whoever is a good citizen cared to tell libev about it by calling
		1534	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1535	event loop blocks next and before C<ev_check> watchers are being called,
		1536	and only in the child after the fork. If whoever good citizen calling
		1537	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1538	handlers will be invoked, too, of course.
		1539
		1540	=over 4
		1541
		1542	=item ev_fork_init (ev_signal *, callback)
		1543
		1544	Initialises and configures the fork watcher - it has no parameters of any
		1545	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1546	believe me.
		1547
1226	=back	1548	=back
1227		1549
1228		1550
1229	=head1 OTHER FUNCTIONS	1551	=head1 OTHER FUNCTIONS
1230		1552
…		…
1392		1714
1393	=item w->sweep () C<ev::embed> only	1715	=item w->sweep () C<ev::embed> only
1394		1716
1395	Invokes C<ev_embed_sweep>.	1717	Invokes C<ev_embed_sweep>.
1396		1718
		1719	=item w->update () C<ev::stat> only
		1720
		1721	Invokes C<ev_stat_stat>.
		1722
1397	=back	1723	=back
1398		1724
1399	=back	1725	=back
1400		1726
1401	Example: Define a class with an IO and idle watcher, start one of them in	1727	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1414	idle (this, &myclass::idle_cb)	1740	idle (this, &myclass::idle_cb)
1415	{	1741	{
1416	io.start (fd, ev::READ);	1742	io.start (fd, ev::READ);
1417	}	1743	}
1418		1744
		1745
		1746	=head1 MACRO MAGIC
		1747
		1748	Libev can be compiled with a variety of options, the most fundemantal is
		1749	C<EV_MULTIPLICITY>. This option determines wether (most) functions and
		1750	callbacks have an initial C<struct ev_loop *> argument.
		1751
		1752	To make it easier to write programs that cope with either variant, the
		1753	following macros are defined:
		1754
		1755	=over 4
		1756
		1757	=item C<EV_A>, C<EV_A_>
		1758
		1759	This provides the loop I<argument> for functions, if one is required ("ev
		1760	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1761	C<EV_A_> is used when other arguments are following. Example:
		1762
		1763	ev_unref (EV_A);
		1764	ev_timer_add (EV_A_ watcher);
		1765	ev_loop (EV_A_ 0);
		1766
		1767	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1768	which is often provided by the following macro.
		1769
		1770	=item C<EV_P>, C<EV_P_>
		1771
		1772	This provides the loop I<parameter> for functions, if one is required ("ev
		1773	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1774	C<EV_P_> is used when other parameters are following. Example:
		1775
		1776	// this is how ev_unref is being declared
		1777	static void ev_unref (EV_P);
		1778
		1779	// this is how you can declare your typical callback
		1780	static void cb (EV_P_ ev_timer *w, int revents)
		1781
		1782	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1783	suitable for use with C<EV_A>.
		1784
		1785	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1786
		1787	Similar to the other two macros, this gives you the value of the default
		1788	loop, if multiple loops are supported ("ev loop default").
		1789
		1790	=back
		1791
		1792	Example: Declare and initialise a check watcher, working regardless of
		1793	wether multiple loops are supported or not.
		1794
		1795	static void
		1796	check_cb (EV_P_ ev_timer *w, int revents)
		1797	{
		1798	ev_check_stop (EV_A_ w);
		1799	}
		1800
		1801	ev_check check;
		1802	ev_check_init (&check, check_cb);
		1803	ev_check_start (EV_DEFAULT_ &check);
		1804	ev_loop (EV_DEFAULT_ 0);
		1805
		1806
1419	=head1 EMBEDDING	1807	=head1 EMBEDDING
1420		1808
1421	Libev can (and often is) directly embedded into host	1809	Libev can (and often is) directly embedded into host
1422	applications. Examples of applications that embed it include the Deliantra	1810	applications. Examples of applications that embed it include the Deliantra
1423	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	1811	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
…		…
1462	ev_vars.h	1850	ev_vars.h
1463	ev_wrap.h	1851	ev_wrap.h
1464		1852
1465	ev_win32.c required on win32 platforms only	1853	ev_win32.c required on win32 platforms only
1466		1854
1467	ev_select.c only when select backend is enabled (which is is by default)	1855	ev_select.c only when select backend is enabled (which is by default)
1468	ev_poll.c only when poll backend is enabled (disabled by default)	1856	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)	1857	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)	1858	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)	1859	ev_port.c only when the solaris port backend is enabled (disabled by default)
1472		1860
1473	F<ev.c> includes the backend files directly when enabled, so you only need	1861	F<ev.c> includes the backend files directly when enabled, so you only need
1474	to compile a single file.	1862	to compile this single file.
1475		1863
1476	=head3 LIBEVENT COMPATIBILITY API	1864	=head3 LIBEVENT COMPATIBILITY API
1477		1865
1478	To include the libevent compatibility API, also include:	1866	To include the libevent compatibility API, also include:
1479		1867
…		…
1492		1880
1493	=head3 AUTOCONF SUPPORT	1881	=head3 AUTOCONF SUPPORT
1494		1882
1495	Instead of using C<EV_STANDALONE=1> and providing your config in	1883	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	1884	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	1885	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
1498	F<config.h> and configure itself accordingly.	1886	include F<config.h> and configure itself accordingly.
1499		1887
1500	For this of course you need the m4 file:	1888	For this of course you need the m4 file:
1501		1889
1502	libev.m4	1890	libev.m4
1503		1891
…		…
1583	otherwise another method will be used as fallback. This is the preferred	1971	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	1972	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	1973	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	1974	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	1975	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	1976	out whether kqueue supports your type of fd properly and use an embedded
1589	kqueue loop.	1977	kqueue loop.
1590		1978
1591	=item EV_USE_PORT	1979	=item EV_USE_PORT
1592		1980
1593	If defined to be C<1>, libev will compile in support for the Solaris	1981	If defined to be C<1>, libev will compile in support for the Solaris
…		…
1629	will have the C<struct ev_loop *> as first argument, and you can create	2017	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	2018	additional independent event loops. Otherwise there will be no support
1631	for multiple event loops and there is no first event loop pointer	2019	for multiple event loops and there is no first event loop pointer
1632	argument. Instead, all functions act on the single default loop.	2020	argument. Instead, all functions act on the single default loop.
1633		2021
1634	=item EV_PERIODICS	2022	=item EV_PERIODIC_ENABLE
1635		2023
1636	If undefined or defined to be C<1>, then periodic timers are supported,	2024	If undefined or defined to be C<1>, then periodic timers are supported. If
1637	otherwise not. This saves a few kb of code.	2025	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2026	code.
		2027
		2028	=item EV_EMBED_ENABLE
		2029
		2030	If undefined or defined to be C<1>, then embed watchers are supported. If
		2031	defined to be C<0>, then they are not.
		2032
		2033	=item EV_STAT_ENABLE
		2034
		2035	If undefined or defined to be C<1>, then stat watchers are supported. If
		2036	defined to be C<0>, then they are not.
		2037
		2038	=item EV_FORK_ENABLE
		2039
		2040	If undefined or defined to be C<1>, then fork watchers are supported. If
		2041	defined to be C<0>, then they are not.
		2042
		2043	=item EV_MINIMAL
		2044
		2045	If you need to shave off some kilobytes of code at the expense of some
		2046	speed, define this symbol to C<1>. Currently only used for gcc to override
		2047	some inlining decisions, saves roughly 30% codesize of amd64.
		2048
		2049	=item EV_PID_HASHSIZE
		2050
		2051	C<ev_child> watchers use a small hash table to distribute workload by
		2052	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2053	than enough. If you need to manage thousands of children you might want to
		2054	increase this value.
1638		2055
1639	=item EV_COMMON	2056	=item EV_COMMON
1640		2057
1641	By default, all watchers have a C<void *data> member. By redefining	2058	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	2059	this macro to a something else you can include more and other types of
…		…
1647		2064
1648	#define EV_COMMON \	2065	#define EV_COMMON \
1649	SV self; / contains this struct */ \	2066	SV self; / contains this struct */ \
1650	SV cb_sv, fh /* note no trailing ";" */	2067	SV cb_sv, fh /* note no trailing ";" */
1651		2068
1652	=item EV_CB_DECLARE(type)	2069	=item EV_CB_DECLARE (type)
1653		2070
1654	=item EV_CB_INVOKE(watcher,revents)	2071	=item EV_CB_INVOKE (watcher, revents)
1655		2072
1656	=item ev_set_cb(ev,cb)	2073	=item ev_set_cb (ev, cb)
1657		2074
1658	Can be used to change the callback member declaration in each watcher,	2075	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	2076	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	2077	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	2078	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	2079	avoid the C<struct ev_loop *> as first argument in all cases, or to use
1663	calls instead of plain function calls in C++.	2080	method calls instead of plain function calls in C++.
1664		2081
1665	=head2 EXAMPLES	2082	=head2 EXAMPLES
1666		2083
1667	For a real-world example of a program the includes libev	2084	For a real-world example of a program the includes libev
1668	verbatim, you can have a look at the EV perl module	2085	verbatim, you can have a look at the EV perl module
…		…
1685	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2102	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1686		2103
1687	#include "ev_cpp.h"	2104	#include "ev_cpp.h"
1688	#include "ev.c"	2105	#include "ev.c"
1689		2106
		2107
		2108	=head1 COMPLEXITIES
		2109
		2110	In this section the complexities of (many of) the algorithms used inside
		2111	libev will be explained. For complexity discussions about backends see the
		2112	documentation for C<ev_default_init>.
		2113
		2114	=over 4
		2115
		2116	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
		2117
		2118	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
		2119
		2120	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
		2121
		2122	=item Stopping check/prepare/idle watchers: O(1)
		2123
		2124	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))
		2125
		2126	=item Finding the next timer per loop iteration: O(1)
		2127
		2128	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		2129
		2130	=item Activating one watcher: O(1)
		2131
		2132	=back
		2133
		2134
1690	=head1 AUTHOR	2135	=head1 AUTHOR
1691		2136
1692	Marc Lehmann <libev@schmorp.de>.	2137	Marc Lehmann <libev@schmorp.de>.
1693		2138

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Comparing libev/ev.pod (file contents): Revision 1.40 by root, Sat Nov 24 10:15:16 2007 UTC vs. Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC

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Revision 1.40 by root, Sat Nov 24 10:15:16 2007 UTC vs.
Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC