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

Comparing libev/ev.pod (file contents):
Revision 1.39 by root, Sat Nov 24 10:10:26 2007 UTC vs.
Revision 1.61 by root, Thu Nov 29 12:21:05 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>), the Linux C<inotify> interface
29	events (related to SIGCHLD), and event watchers dealing with the event	71	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
30	loop mechanism itself (idle, prepare and check watchers). It also is quite	72	with customised rescheduling (C<ev_periodic>), synchronous signals
		73	(C<ev_signal>), process status change events (C<ev_child>), and event
		74	watchers dealing with the event loop mechanism itself (C<ev_idle>,
		75	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
		76	file watchers (C<ev_stat>) and even limited support for fork events
		77	(C<ev_fork>).
		78
		79	It also is quite fast (see this
31	fast (see this L<benchmark\|http://libev.schmorp.de/bench.html> comparing	80	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent
32	it to libevent for example).	81	for example).
33		82
34	=head1 CONVENTIONS	83	=head1 CONVENTIONS
35		84
36	Libev is very configurable. In this manual the default configuration	85	Libev is very configurable. In this manual the default configuration will
37	will be described, which supports multiple event loops. For more info	86	be described, which supports multiple event loops. For more info about
38	about various configuration options please have a look at the file	87	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	88	this manual. If libev was configured without support for multiple event
40	support for multiple event loops, then all functions taking an initial	89	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 *>)	90	(which is always of type C<struct ev_loop *>) will not have this argument.
42	will not have this argument.
43		91
44	=head1 TIME REPRESENTATION	92	=head1 TIME REPRESENTATION
45		93
46	Libev represents time as a single floating point number, representing the	94	Libev represents time as a single floating point number, representing the
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	95	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	96	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	97	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	98	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	99	it, you should treat it as such.
52		100
53
54	=head1 GLOBAL FUNCTIONS	101	=head1 GLOBAL FUNCTIONS
55		102
56	These functions can be called anytime, even before initialising the	103	These functions can be called anytime, even before initialising the
57	library in any way.	104	library in any way.
58		105
…		…
77	Usually, it's a good idea to terminate if the major versions mismatch,	124	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	125	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	126	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	127	not a problem.
81		128
82	Example: make sure we haven't accidentally been linked against the wrong	129	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	130	version.
84		131
85	assert (("libev version mismatch",	132	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	133	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	134	&& ev_version_minor () >= EV_VERSION_MINOR));
88		135
…		…
118		165
119	See the description of C<ev_embed> watchers for more info.	166	See the description of C<ev_embed> watchers for more info.
120		167
121	=item ev_set_allocator (void (cb)(void *ptr, long size))	168	=item ev_set_allocator (void (cb)(void *ptr, long size))
122		169
123	Sets the allocation function to use (the prototype is similar to the	170	Sets the allocation function to use (the prototype is similar - the
124	realloc C function, the semantics are identical). It is used to allocate	171	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	172	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	173	memory needs to be allocated, the library might abort or take some
127	destructive action. The default is your system realloc function.	174	potentially destructive action. The default is your system realloc
		175	function.
128		176
129	You could override this function in high-availability programs to, say,	177	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,	178	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.	179	or even to sleep a while and retry until some memory is available.
132		180
133	Example: replace the libev allocator with one that waits a bit and then	181	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	182	retries).
135		183
136	static void *	184	static void *
137	persistent_realloc (void *ptr, long size)	185	persistent_realloc (void *ptr, size_t size)
138	{	186	{
139	for (;;)	187	for (;;)
140	{	188	{
141	void *newptr = realloc (ptr, size);	189	void *newptr = realloc (ptr, size);
142		190
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	206	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	207	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	208	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	209	(such as abort).
162		210
163	Example: do the same thing as libev does internally:	211	Example: This is basically the same thing that libev does internally, too.
164		212
165	static void	213	static void
166	fatal_error (const char *msg)	214	fatal_error (const char *msg)
167	{	215	{
168	perror (msg);	216	perror (msg);
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	362	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	363	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	364	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).	365	undefined behaviour (or a failed assertion if assertions are enabled).
318		366
319	Example: try to create a event loop that uses epoll and nothing else.	367	Example: Try to create a event loop that uses epoll and nothing else.
320		368
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	369	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
322	if (!epoller)	370	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	371	fatal ("no epoll found here, maybe it hides under your chair");
324		372
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	471	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	472	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	473	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	474	were used, return, otherwise continue with step *.
427		475
428	Example: queue some jobs and then loop until no events are outsanding	476	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	477	anymore.
430		478
431	... queue jobs here, make sure they register event watchers as long	479	... 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..)	480	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	481	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	501	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	502	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	503	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>.	504	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		505
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	506	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	507	running when nothing else is active.
460		508
461	struct dv_signal exitsig;	509	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	510	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	511	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	512	evf_unref (loop);
465		513
466	Example: for some weird reason, unregister the above signal handler again.	514	Example: For some weird reason, unregister the above signal handler again.
467		515
468	ev_ref (myloop);	516	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	517	ev_signal_stop (loop, &exitsig);
470		518
471	=back	519	=back
		520
472		521
473	=head1 ANATOMY OF A WATCHER	522	=head1 ANATOMY OF A WATCHER
474		523
475	A watcher is a structure that you create and register to record your	524	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	525	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.	592	The signal specified in the C<ev_signal> watcher has been received by a thread.
544		593
545	=item C<EV_CHILD>	594	=item C<EV_CHILD>
546		595
547	The pid specified in the C<ev_child> watcher has received a status change.	596	The pid specified in the C<ev_child> watcher has received a status change.
		597
		598	=item C<EV_STAT>
		599
		600	The path specified in the C<ev_stat> watcher changed its attributes somehow.
548		601
549	=item C<EV_IDLE>	602	=item C<EV_IDLE>
550		603
551	The C<ev_idle> watcher has determined that you have nothing better to do.	604	The C<ev_idle> watcher has determined that you have nothing better to do.
552		605
…		…
560	received events. Callbacks of both watcher types can start and stop as	613	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	614	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	615	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
563	C<ev_loop> from blocking).	616	C<ev_loop> from blocking).
564		617
		618	=item C<EV_EMBED>
		619
		620	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		621
		622	=item C<EV_FORK>
		623
		624	The event loop has been resumed in the child process after fork (see
		625	C<ev_fork>).
		626
565	=item C<EV_ERROR>	627	=item C<EV_ERROR>
566		628
567	An unspecified error has occured, the watcher has been stopped. This might	629	An unspecified error has occured, the watcher has been stopped. This might
568	happen because the watcher could not be properly started because libev	630	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	631	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	638	with the error from read() or write(). This will not work in multithreaded
577	programs, though, so beware.	639	programs, though, so beware.
578		640
579	=back	641	=back
580		642
581	=head2 SUMMARY OF GENERIC WATCHER FUNCTIONS	643	=head2 GENERIC WATCHER FUNCTIONS
582		644
583	In the following description, C<TYPE> stands for the watcher type,	645	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.	646	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.
585		647
586	=over 4	648	=over 4
…		…
595	which rolls both calls into one.	657	which rolls both calls into one.
596		658
597	You can reinitialise a watcher at any time as long as it has been stopped	659	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.	660	(or never started) and there are no pending events outstanding.
599		661
600	The callbakc is always of type C<void ()(ev_loop loop, ev_TYPE *watcher,	662	The callback is always of type C<void ()(ev_loop loop, ev_TYPE *watcher,
601	int revents)>.	663	int revents)>.
602		664
603	=item C<ev_TYPE_set> (ev_TYPE *, [args])	665	=item C<ev_TYPE_set> (ev_TYPE *, [args])
604		666
605	This macro initialises the type-specific parts of a watcher. You need to	667	This macro initialises the type-specific parts of a watcher. You need to
…		…
643	events but its callback has not yet been invoked). As long as a watcher	705	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	706	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	707	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to
646	libev (e.g. you cnanot C<free ()> it).	708	libev (e.g. you cnanot C<free ()> it).
647		709
648	=item callback = ev_cb (ev_TYPE *watcher)	710	=item callback ev_cb (ev_TYPE *watcher)
649		711
650	Returns the callback currently set on the watcher.	712	Returns the callback currently set on the watcher.
651		713
652	=item ev_cb_set (ev_TYPE *watcher, callback)	714	=item ev_cb_set (ev_TYPE *watcher, callback)
653		715
…		…
681	{	743	{
682	struct my_io w = (struct my_io )w_;	744	struct my_io w = (struct my_io )w_;
683	...	745	...
684	}	746	}
685		747
686	More interesting and less C-conformant ways of catsing your callback type	748	More interesting and less C-conformant ways of casting your callback type
687	have been omitted....	749	instead have been omitted.
		750
		751	Another common scenario is having some data structure with multiple
		752	watchers:
		753
		754	struct my_biggy
		755	{
		756	int some_data;
		757	ev_timer t1;
		758	ev_timer t2;
		759	}
		760
		761	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		762	you need to use C<offsetof>:
		763
		764	#include <stddef.h>
		765
		766	static void
		767	t1_cb (EV_P_ struct ev_timer *w, int revents)
		768	{
		769	struct my_biggy big = (struct my_biggy *
		770	(((char *)w) - offsetof (struct my_biggy, t1));
		771	}
		772
		773	static void
		774	t2_cb (EV_P_ struct ev_timer *w, int revents)
		775	{
		776	struct my_biggy big = (struct my_biggy *
		777	(((char *)w) - offsetof (struct my_biggy, t2));
		778	}
688		779
689		780
690	=head1 WATCHER TYPES	781	=head1 WATCHER TYPES
691		782
692	This section describes each watcher in detail, but will not repeat	783	This section describes each watcher in detail, but will not repeat
693	information given in the last section.	784	information given in the last section. Any initialisation/set macros,
		785	functions and members specific to the watcher type are explained.
694		786
		787	Members are additionally marked with either I<[read-only]>, meaning that,
		788	while the watcher is active, you can look at the member and expect some
		789	sensible content, but you must not modify it (you can modify it while the
		790	watcher is stopped to your hearts content), or I<[read-write]>, which
		791	means you can expect it to have some sensible content while the watcher
		792	is active, but you can also modify it. Modifying it may not do something
		793	sensible or take immediate effect (or do anything at all), but libev will
		794	not crash or malfunction in any way.
695		795
		796
696	=head2 C<ev_io> - is this file descriptor readable or writable	797	=head2 C<ev_io> - is this file descriptor readable or writable?
697		798
698	I/O watchers check whether a file descriptor is readable or writable	799	I/O watchers check whether a file descriptor is readable or writable
699	in each iteration of the event loop (This behaviour is called	800	in each iteration of the event loop, or, more precisely, when reading
700	level-triggering because you keep receiving events as long as the	801	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	802	some data. This behaviour is called level-triggering because you keep
702	act on the event and neither want to receive future events).	803	receiving events as long as the condition persists. Remember you can stop
		804	the watcher if you don't want to act on the event and neither want to
		805	receive future events.
703		806
704	In general you can register as many read and/or write event watchers per	807	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	808	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	809	descriptors to non-blocking mode is also usually a good idea (but not
707	required if you know what you are doing).	810	required if you know what you are doing).
708		811
709	You have to be careful with dup'ed file descriptors, though. Some backends	812	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	813	(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	814	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	815	to the same underlying file/socket/etc. description (that is, they share
713	the same underlying "file open").	816	the same underlying "file open").
714		817
715	If you must do this, then force the use of a known-to-be-good backend	818	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	819	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
717	C<EVBACKEND_POLL>).	820	C<EVBACKEND_POLL>).
718		821
		822	Another thing you have to watch out for is that it is quite easy to
		823	receive "spurious" readyness notifications, that is your callback might
		824	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
		825	because there is no data. Not only are some backends known to create a
		826	lot of those (for example solaris ports), it is very easy to get into
		827	this situation even with a relatively standard program structure. Thus
		828	it is best to always use non-blocking I/O: An extra C<read>(2) returning
		829	C<EAGAIN> is far preferable to a program hanging until some data arrives.
		830
		831	If you cannot run the fd in non-blocking mode (for example you should not
		832	play around with an Xlib connection), then you have to seperately re-test
		833	wether a file descriptor is really ready with a known-to-be good interface
		834	such as poll (fortunately in our Xlib example, Xlib already does this on
		835	its own, so its quite safe to use).
		836
719	=over 4	837	=over 4
720		838
721	=item ev_io_init (ev_io *, callback, int fd, int events)	839	=item ev_io_init (ev_io *, callback, int fd, int events)
722		840
723	=item ev_io_set (ev_io *, int fd, int events)	841	=item ev_io_set (ev_io *, int fd, int events)
724		842
725	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive	843	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 \|	844	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
727	EV_WRITE> to receive the given events.	845	C<EV_READ \| EV_WRITE> to receive the given events.
728		846
729	Please note that most of the more scalable backend mechanisms (for example	847	=item int fd [read-only]
730	epoll and solaris ports) can result in spurious readyness notifications	848
731	for file descriptors, so you practically need to use non-blocking I/O (and	849	The file descriptor being watched.
732	treat callback invocation as hint only), or retest separately with a safe	850
733	interface before doing I/O (XLib can do this), or force the use of either	851	=item int events [read-only]
734	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this	852
735	problem. Also note that it is quite easy to have your callback invoked	853	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		854
740	=back	855	=back
741		856
742	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	857	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	858	readable, but only once. Since it is likely line-buffered, you could
744	attempt to read a whole line in the callback:	859	attempt to read a whole line in the callback.
745		860
746	static void	861	static void
747	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	862	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
748	{	863	{
749	ev_io_stop (loop, w);	864	ev_io_stop (loop, w);
…		…
756	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	871	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
757	ev_io_start (loop, &stdin_readable);	872	ev_io_start (loop, &stdin_readable);
758	ev_loop (loop, 0);	873	ev_loop (loop, 0);
759		874
760		875
761	=head2 C<ev_timer> - relative and optionally recurring timeouts	876	=head2 C<ev_timer> - relative and optionally repeating timeouts
762		877
763	Timer watchers are simple relative timers that generate an event after a	878	Timer watchers are simple relative timers that generate an event after a
764	given time, and optionally repeating in regular intervals after that.	879	given time, and optionally repeating in regular intervals after that.
765		880
766	The timers are based on real time, that is, if you register an event that	881	The timers are based on real time, that is, if you register an event that
…		…
801	=item ev_timer_again (loop)	916	=item ev_timer_again (loop)
802		917
803	This will act as if the timer timed out and restart it again if it is	918	This will act as if the timer timed out and restart it again if it is
804	repeating. The exact semantics are:	919	repeating. The exact semantics are:
805		920
		921	If the timer is pending, its pending status is cleared.
		922
806	If the timer is started but nonrepeating, stop it.	923	If the timer is started but nonrepeating, stop it (as if it timed out).
807		924
808	If the timer is repeating, either start it if necessary (with the repeat	925	If the timer is repeating, either start it if necessary (with the
809	value), or reset the running timer to the repeat value.	926	C<repeat> value), or reset the running timer to the C<repeat> value.
810		927
811	This sounds a bit complicated, but here is a useful and typical	928	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	929	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	930	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	931	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	932	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	933	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	934	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.	935	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
		936	automatically restart it if need be.
		937
		938	That means you can ignore the C<after> value and C<ev_timer_start>
		939	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
		940
		941	ev_timer_init (timer, callback, 0., 5.);
		942	ev_timer_again (loop, timer);
		943	...
		944	timer->again = 17.;
		945	ev_timer_again (loop, timer);
		946	...
		947	timer->again = 10.;
		948	ev_timer_again (loop, timer);
		949
		950	This is more slightly efficient then stopping/starting the timer each time
		951	you want to modify its timeout value.
		952
		953	=item ev_tstamp repeat [read-write]
		954
		955	The current C<repeat> value. Will be used each time the watcher times out
		956	or C<ev_timer_again> is called and determines the next timeout (if any),
		957	which is also when any modifications are taken into account.
819		958
820	=back	959	=back
821		960
822	Example: create a timer that fires after 60 seconds.	961	Example: Create a timer that fires after 60 seconds.
823		962
824	static void	963	static void
825	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	964	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
826	{	965	{
827	.. one minute over, w is actually stopped right here	966	.. one minute over, w is actually stopped right here
…		…
829		968
830	struct ev_timer mytimer;	969	struct ev_timer mytimer;
831	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	970	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
832	ev_timer_start (loop, &mytimer);	971	ev_timer_start (loop, &mytimer);
833		972
834	Example: create a timeout timer that times out after 10 seconds of	973	Example: Create a timeout timer that times out after 10 seconds of
835	inactivity.	974	inactivity.
836		975
837	static void	976	static void
838	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	977	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
839	{	978	{
…		…
848	// and in some piece of code that gets executed on any "activity":	987	// and in some piece of code that gets executed on any "activity":
849	// reset the timeout to start ticking again at 10 seconds	988	// reset the timeout to start ticking again at 10 seconds
850	ev_timer_again (&mytimer);	989	ev_timer_again (&mytimer);
851		990
852		991
853	=head2 C<ev_periodic> - to cron or not to cron	992	=head2 C<ev_periodic> - to cron or not to cron?
854		993
855	Periodic watchers are also timers of a kind, but they are very versatile	994	Periodic watchers are also timers of a kind, but they are very versatile
856	(and unfortunately a bit complex).	995	(and unfortunately a bit complex).
857		996
858	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	997	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	1089	Simply stops and restarts the periodic watcher again. This is only useful
951	when you changed some parameters or the reschedule callback would return	1090	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	1091	a different time than the last time it was called (e.g. in a crond like
953	program when the crontabs have changed).	1092	program when the crontabs have changed).
954		1093
		1094	=item ev_tstamp interval [read-write]
		1095
		1096	The current interval value. Can be modified any time, but changes only
		1097	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1098	called.
		1099
		1100	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
		1101
		1102	The current reschedule callback, or C<0>, if this functionality is
		1103	switched off. Can be changed any time, but changes only take effect when
		1104	the periodic timer fires or C<ev_periodic_again> is being called.
		1105
955	=back	1106	=back
956		1107
957	Example: call a callback every hour, or, more precisely, whenever the	1108	Example: Call a callback every hour, or, more precisely, whenever the
958	system clock is divisible by 3600. The callback invocation times have	1109	system clock is divisible by 3600. The callback invocation times have
959	potentially a lot of jittering, but good long-term stability.	1110	potentially a lot of jittering, but good long-term stability.
960		1111
961	static void	1112	static void
962	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1113	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
966		1117
967	struct ev_periodic hourly_tick;	1118	struct ev_periodic hourly_tick;
968	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1119	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
969	ev_periodic_start (loop, &hourly_tick);	1120	ev_periodic_start (loop, &hourly_tick);
970		1121
971	Example: the same as above, but use a reschedule callback to do it:	1122	Example: The same as above, but use a reschedule callback to do it:
972		1123
973	#include <math.h>	1124	#include <math.h>
974		1125
975	static ev_tstamp	1126	static ev_tstamp
976	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1127	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
978	return fmod (now, 3600.) + 3600.;	1129	return fmod (now, 3600.) + 3600.;
979	}	1130	}
980		1131
981	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1132	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
982		1133
983	Example: call a callback every hour, starting now:	1134	Example: Call a callback every hour, starting now:
984		1135
985	struct ev_periodic hourly_tick;	1136	struct ev_periodic hourly_tick;
986	ev_periodic_init (&hourly_tick, clock_cb,	1137	ev_periodic_init (&hourly_tick, clock_cb,
987	fmod (ev_now (loop), 3600.), 3600., 0);	1138	fmod (ev_now (loop), 3600.), 3600., 0);
988	ev_periodic_start (loop, &hourly_tick);	1139	ev_periodic_start (loop, &hourly_tick);
989		1140
990		1141
991	=head2 C<ev_signal> - signal me when a signal gets signalled	1142	=head2 C<ev_signal> - signal me when a signal gets signalled!
992		1143
993	Signal watchers will trigger an event when the process receives a specific	1144	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	1145	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	1146	will try it's best to deliver signals synchronously, i.e. as part of the
996	normal event processing, like any other event.	1147	normal event processing, like any other event.
…		…
1009	=item ev_signal_set (ev_signal *, int signum)	1160	=item ev_signal_set (ev_signal *, int signum)
1010		1161
1011	Configures the watcher to trigger on the given signal number (usually one	1162	Configures the watcher to trigger on the given signal number (usually one
1012	of the C<SIGxxx> constants).	1163	of the C<SIGxxx> constants).
1013		1164
		1165	=item int signum [read-only]
		1166
		1167	The signal the watcher watches out for.
		1168
1014	=back	1169	=back
1015		1170
1016		1171
1017	=head2 C<ev_child> - wait for pid status changes	1172	=head2 C<ev_child> - watch out for process status changes
1018		1173
1019	Child watchers trigger when your process receives a SIGCHLD in response to	1174	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).	1175	some child status changes (most typically when a child of yours dies).
1021		1176
1022	=over 4	1177	=over 4
…		…
1030	at the C<rstatus> member of the C<ev_child> watcher structure to see	1185	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	1186	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	1187	C<waitpid> documentation). The C<rpid> member contains the pid of the
1033	process causing the status change.	1188	process causing the status change.
1034		1189
		1190	=item int pid [read-only]
		1191
		1192	The process id this watcher watches out for, or C<0>, meaning any process id.
		1193
		1194	=item int rpid [read-write]
		1195
		1196	The process id that detected a status change.
		1197
		1198	=item int rstatus [read-write]
		1199
		1200	The process exit/trace status caused by C<rpid> (see your systems
		1201	C<waitpid> and C<sys/wait.h> documentation for details).
		1202
1035	=back	1203	=back
1036		1204
1037	Example: try to exit cleanly on SIGINT and SIGTERM.	1205	Example: Try to exit cleanly on SIGINT and SIGTERM.
1038		1206
1039	static void	1207	static void
1040	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1208	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1041	{	1209	{
1042	ev_unloop (loop, EVUNLOOP_ALL);	1210	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1045	struct ev_signal signal_watcher;	1213	struct ev_signal signal_watcher;
1046	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1214	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1047	ev_signal_start (loop, &sigint_cb);	1215	ev_signal_start (loop, &sigint_cb);
1048		1216
1049		1217
		1218	=head2 C<ev_stat> - did the file attributes just change?
		1219
		1220	This watches a filesystem path for attribute changes. That is, it calls
		1221	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1222	compared to the last time, invoking the callback if it did.
		1223
		1224	The path does not need to exist: changing from "path exists" to "path does
		1225	not exist" is a status change like any other. The condition "path does
		1226	not exist" is signified by the C<st_nlink> field being zero (which is
		1227	otherwise always forced to be at least one) and all the other fields of
		1228	the stat buffer having unspecified contents.
		1229
		1230	The path I<should> be absolute and I<must not> end in a slash. If it is
		1231	relative and your working directory changes, the behaviour is undefined.
		1232
		1233	Since there is no standard to do this, the portable implementation simply
		1234	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1235	can specify a recommended polling interval for this case. If you specify
		1236	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1237	unspecified default> value will be used (which you can expect to be around
		1238	five seconds, although this might change dynamically). Libev will also
		1239	impose a minimum interval which is currently around C<0.1>, but thats
		1240	usually overkill.
		1241
		1242	This watcher type is not meant for massive numbers of stat watchers,
		1243	as even with OS-supported change notifications, this can be
		1244	resource-intensive.
		1245
		1246	At the time of this writing, only the Linux inotify interface is
		1247	implemented (implementing kqueue support is left as an exercise for the
		1248	reader). Inotify will be used to give hints only and should not change the
		1249	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1250	to fall back to regular polling again even with inotify, but changes are
		1251	usually detected immediately, and if the file exists there will be no
		1252	polling.
		1253
		1254	=over 4
		1255
		1256	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
		1257
		1258	=item ev_stat_set (ev_stat , const char path, ev_tstamp interval)
		1259
		1260	Configures the watcher to wait for status changes of the given
		1261	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1262	be detected and should normally be specified as C<0> to let libev choose
		1263	a suitable value. The memory pointed to by C<path> must point to the same
		1264	path for as long as the watcher is active.
		1265
		1266	The callback will be receive C<EV_STAT> when a change was detected,
		1267	relative to the attributes at the time the watcher was started (or the
		1268	last change was detected).
		1269
		1270	=item ev_stat_stat (ev_stat *)
		1271
		1272	Updates the stat buffer immediately with new values. If you change the
		1273	watched path in your callback, you could call this fucntion to avoid
		1274	detecting this change (while introducing a race condition). Can also be
		1275	useful simply to find out the new values.
		1276
		1277	=item ev_statdata attr [read-only]
		1278
		1279	The most-recently detected attributes of the file. Although the type is of
		1280	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1281	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1282	was some error while C<stat>ing the file.
		1283
		1284	=item ev_statdata prev [read-only]
		1285
		1286	The previous attributes of the file. The callback gets invoked whenever
		1287	C<prev> != C<attr>.
		1288
		1289	=item ev_tstamp interval [read-only]
		1290
		1291	The specified interval.
		1292
		1293	=item const char *path [read-only]
		1294
		1295	The filesystem path that is being watched.
		1296
		1297	=back
		1298
		1299	Example: Watch C</etc/passwd> for attribute changes.
		1300
		1301	static void
		1302	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1303	{
		1304	/* /etc/passwd changed in some way */
		1305	if (w->attr.st_nlink)
		1306	{
		1307	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1308	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1309	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1310	}
		1311	else
		1312	/* you shalt not abuse printf for puts */
		1313	puts ("wow, /etc/passwd is not there, expect problems. "
		1314	"if this is windows, they already arrived\n");
		1315	}
		1316
		1317	...
		1318	ev_stat passwd;
		1319
		1320	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1321	ev_stat_start (loop, &passwd);
		1322
		1323
1050	=head2 C<ev_idle> - when you've got nothing better to do	1324	=head2 C<ev_idle> - when you've got nothing better to do...
1051		1325
1052	Idle watchers trigger events when there are no other events are pending	1326	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	1327	(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,	1328	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	1329	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,	1347	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1074	believe me.	1348	believe me.
1075		1349
1076	=back	1350	=back
1077		1351
1078	Example: dynamically allocate an C<ev_idle>, start it, and in the	1352	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1079	callback, free it. Alos, use no error checking, as usual.	1353	callback, free it. Also, use no error checking, as usual.
1080		1354
1081	static void	1355	static void
1082	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1356	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1083	{	1357	{
1084	free (w);	1358	free (w);
…		…
1089	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1363	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1090	ev_idle_init (idle_watcher, idle_cb);	1364	ev_idle_init (idle_watcher, idle_cb);
1091	ev_idle_start (loop, idle_cb);	1365	ev_idle_start (loop, idle_cb);
1092		1366
1093		1367
1094	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	1368	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1095		1369
1096	Prepare and check watchers are usually (but not always) used in tandem:	1370	Prepare and check watchers are usually (but not always) used in tandem:
1097	prepare watchers get invoked before the process blocks and check watchers	1371	prepare watchers get invoked before the process blocks and check watchers
1098	afterwards.	1372	afterwards.
1099		1373
		1374	You I<must not> call C<ev_loop> or similar functions that enter
		1375	the current event loop from either C<ev_prepare> or C<ev_check>
		1376	watchers. Other loops than the current one are fine, however. The
		1377	rationale behind this is that you do not need to check for recursion in
		1378	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
		1379	C<ev_check> so if you have one watcher of each kind they will always be
		1380	called in pairs bracketing the blocking call.
		1381
1100	Their main purpose is to integrate other event mechanisms into libev and	1382	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	1383	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	1384	variable changes, implement your own watchers, integrate net-snmp or a
1103	coroutine library and lots more.	1385	coroutine library and lots more. They are also occasionally useful if
		1386	you cache some data and want to flush it before blocking (for example,
		1387	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
		1388	watcher).
1104		1389
1105	This is done by examining in each prepare call which file descriptors need	1390	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	1391	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	1392	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	1393	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>	1415	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.	1416	macros, but using them is utterly, utterly and completely pointless.
1132		1417
1133	=back	1418	=back
1134		1419
1135	Example: TODO.	1420	Example: To include a library such as adns, you would add IO watchers
		1421	and a timeout watcher in a prepare handler, as required by libadns, and
		1422	in a check watcher, destroy them and call into libadns. What follows is
		1423	pseudo-code only of course:
1136		1424
		1425	static ev_io iow [nfd];
		1426	static ev_timer tw;
1137		1427
		1428	static void
		1429	io_cb (ev_loop loop, ev_io w, int revents)
		1430	{
		1431	// set the relevant poll flags
		1432	// could also call adns_processreadable etc. here
		1433	struct pollfd fd = (struct pollfd )w->data;
		1434	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1435	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1436	}
		1437
		1438	// create io watchers for each fd and a timer before blocking
		1439	static void
		1440	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1441	{
		1442	int timeout = 3600000;truct pollfd fds [nfd];
		1443	// actual code will need to loop here and realloc etc.
		1444	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1445
		1446	/* the callback is illegal, but won't be called as we stop during check */
		1447	ev_timer_init (&tw, 0, timeout * 1e-3);
		1448	ev_timer_start (loop, &tw);
		1449
		1450	// create on ev_io per pollfd
		1451	for (int i = 0; i < nfd; ++i)
		1452	{
		1453	ev_io_init (iow + i, io_cb, fds [i].fd,
		1454	((fds [i].events & POLLIN ? EV_READ : 0)
		1455	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1456
		1457	fds [i].revents = 0;
		1458	iow [i].data = fds + i;
		1459	ev_io_start (loop, iow + i);
		1460	}
		1461	}
		1462
		1463	// stop all watchers after blocking
		1464	static void
		1465	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1466	{
		1467	ev_timer_stop (loop, &tw);
		1468
		1469	for (int i = 0; i < nfd; ++i)
		1470	ev_io_stop (loop, iow + i);
		1471
		1472	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1473	}
		1474
		1475
1138	=head2 C<ev_embed> - when one backend isn't enough	1476	=head2 C<ev_embed> - when one backend isn't enough...
1139		1477
1140	This is a rather advanced watcher type that lets you embed one event loop	1478	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	1479	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	1480	loop, other types of watchers might be handled in a delayed or incorrect
1143	fashion and must not be used).	1481	fashion and must not be used).
…		…
1221		1559
1222	Make a single, non-blocking sweep over the embedded loop. This works	1560	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	1561	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1224	apropriate way for embedded loops.	1562	apropriate way for embedded loops.
1225		1563
		1564	=item struct ev_loop *loop [read-only]
		1565
		1566	The embedded event loop.
		1567
		1568	=back
		1569
		1570
		1571	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1572
		1573	Fork watchers are called when a C<fork ()> was detected (usually because
		1574	whoever is a good citizen cared to tell libev about it by calling
		1575	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1576	event loop blocks next and before C<ev_check> watchers are being called,
		1577	and only in the child after the fork. If whoever good citizen calling
		1578	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1579	handlers will be invoked, too, of course.
		1580
		1581	=over 4
		1582
		1583	=item ev_fork_init (ev_signal *, callback)
		1584
		1585	Initialises and configures the fork watcher - it has no parameters of any
		1586	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1587	believe me.
		1588
1226	=back	1589	=back
1227		1590
1228		1591
1229	=head1 OTHER FUNCTIONS	1592	=head1 OTHER FUNCTIONS
1230		1593
…		…
1392		1755
1393	=item w->sweep () C<ev::embed> only	1756	=item w->sweep () C<ev::embed> only
1394		1757
1395	Invokes C<ev_embed_sweep>.	1758	Invokes C<ev_embed_sweep>.
1396		1759
		1760	=item w->update () C<ev::stat> only
		1761
		1762	Invokes C<ev_stat_stat>.
		1763
1397	=back	1764	=back
1398		1765
1399	=back	1766	=back
1400		1767
1401	Example: Define a class with an IO and idle watcher, start one of them in	1768	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1413	: io (this, &myclass::io_cb),	1780	: io (this, &myclass::io_cb),
1414	idle (this, &myclass::idle_cb)	1781	idle (this, &myclass::idle_cb)
1415	{	1782	{
1416	io.start (fd, ev::READ);	1783	io.start (fd, ev::READ);
1417	}	1784	}
		1785
		1786
		1787	=head1 MACRO MAGIC
		1788
		1789	Libev can be compiled with a variety of options, the most fundemantal is
		1790	C<EV_MULTIPLICITY>. This option determines wether (most) functions and
		1791	callbacks have an initial C<struct ev_loop *> argument.
		1792
		1793	To make it easier to write programs that cope with either variant, the
		1794	following macros are defined:
		1795
		1796	=over 4
		1797
		1798	=item C<EV_A>, C<EV_A_>
		1799
		1800	This provides the loop I<argument> for functions, if one is required ("ev
		1801	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1802	C<EV_A_> is used when other arguments are following. Example:
		1803
		1804	ev_unref (EV_A);
		1805	ev_timer_add (EV_A_ watcher);
		1806	ev_loop (EV_A_ 0);
		1807
		1808	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1809	which is often provided by the following macro.
		1810
		1811	=item C<EV_P>, C<EV_P_>
		1812
		1813	This provides the loop I<parameter> for functions, if one is required ("ev
		1814	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1815	C<EV_P_> is used when other parameters are following. Example:
		1816
		1817	// this is how ev_unref is being declared
		1818	static void ev_unref (EV_P);
		1819
		1820	// this is how you can declare your typical callback
		1821	static void cb (EV_P_ ev_timer *w, int revents)
		1822
		1823	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1824	suitable for use with C<EV_A>.
		1825
		1826	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1827
		1828	Similar to the other two macros, this gives you the value of the default
		1829	loop, if multiple loops are supported ("ev loop default").
		1830
		1831	=back
		1832
		1833	Example: Declare and initialise a check watcher, working regardless of
		1834	wether multiple loops are supported or not.
		1835
		1836	static void
		1837	check_cb (EV_P_ ev_timer *w, int revents)
		1838	{
		1839	ev_check_stop (EV_A_ w);
		1840	}
		1841
		1842	ev_check check;
		1843	ev_check_init (&check, check_cb);
		1844	ev_check_start (EV_DEFAULT_ &check);
		1845	ev_loop (EV_DEFAULT_ 0);
		1846
1418		1847
1419	=head1 EMBEDDING	1848	=head1 EMBEDDING
1420		1849
1421	Libev can (and often is) directly embedded into host	1850	Libev can (and often is) directly embedded into host
1422	applications. Examples of applications that embed it include the Deliantra	1851	applications. Examples of applications that embed it include the Deliantra
…		…
1462	ev_vars.h	1891	ev_vars.h
1463	ev_wrap.h	1892	ev_wrap.h
1464		1893
1465	ev_win32.c required on win32 platforms only	1894	ev_win32.c required on win32 platforms only
1466		1895
1467	ev_select.c only when select backend is enabled (which is is by default)	1896	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)	1897	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)	1898	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)	1899	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)	1900	ev_port.c only when the solaris port backend is enabled (disabled by default)
1472		1901
1473	F<ev.c> includes the backend files directly when enabled, so you only need	1902	F<ev.c> includes the backend files directly when enabled, so you only need
1474	to compile a single file.	1903	to compile this single file.
1475		1904
1476	=head3 LIBEVENT COMPATIBILITY API	1905	=head3 LIBEVENT COMPATIBILITY API
1477		1906
1478	To include the libevent compatibility API, also include:	1907	To include the libevent compatibility API, also include:
1479		1908
…		…
1492		1921
1493	=head3 AUTOCONF SUPPORT	1922	=head3 AUTOCONF SUPPORT
1494		1923
1495	Instead of using C<EV_STANDALONE=1> and providing your config in	1924	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	1925	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	1926	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
1498	F<config.h> and configure itself accordingly.	1927	include F<config.h> and configure itself accordingly.
1499		1928
1500	For this of course you need the m4 file:	1929	For this of course you need the m4 file:
1501		1930
1502	libev.m4	1931	libev.m4
1503		1932
…		…
1583	otherwise another method will be used as fallback. This is the preferred	2012	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	2013	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	2014	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	2015	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	2016	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	2017	out whether kqueue supports your type of fd properly and use an embedded
1589	kqueue loop.	2018	kqueue loop.
1590		2019
1591	=item EV_USE_PORT	2020	=item EV_USE_PORT
1592		2021
1593	If defined to be C<1>, libev will compile in support for the Solaris	2022	If defined to be C<1>, libev will compile in support for the Solaris
…		…
1596	backend for Solaris 10 systems.	2025	backend for Solaris 10 systems.
1597		2026
1598	=item EV_USE_DEVPOLL	2027	=item EV_USE_DEVPOLL
1599		2028
1600	reserved for future expansion, works like the USE symbols above.	2029	reserved for future expansion, works like the USE symbols above.
		2030
		2031	=item EV_USE_INOTIFY
		2032
		2033	If defined to be C<1>, libev will compile in support for the Linux inotify
		2034	interface to speed up C<ev_stat> watchers. Its actual availability will
		2035	be detected at runtime.
1601		2036
1602	=item EV_H	2037	=item EV_H
1603		2038
1604	The name of the F<ev.h> header file used to include it. The default if	2039	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	2040	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	2064	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	2065	additional independent event loops. Otherwise there will be no support
1631	for multiple event loops and there is no first event loop pointer	2066	for multiple event loops and there is no first event loop pointer
1632	argument. Instead, all functions act on the single default loop.	2067	argument. Instead, all functions act on the single default loop.
1633		2068
1634	=item EV_PERIODICS	2069	=item EV_PERIODIC_ENABLE
1635		2070
1636	If undefined or defined to be C<1>, then periodic timers are supported,	2071	If undefined or defined to be C<1>, then periodic timers are supported. If
1637	otherwise not. This saves a few kb of code.	2072	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2073	code.
		2074
		2075	=item EV_EMBED_ENABLE
		2076
		2077	If undefined or defined to be C<1>, then embed watchers are supported. If
		2078	defined to be C<0>, then they are not.
		2079
		2080	=item EV_STAT_ENABLE
		2081
		2082	If undefined or defined to be C<1>, then stat watchers are supported. If
		2083	defined to be C<0>, then they are not.
		2084
		2085	=item EV_FORK_ENABLE
		2086
		2087	If undefined or defined to be C<1>, then fork watchers are supported. If
		2088	defined to be C<0>, then they are not.
		2089
		2090	=item EV_MINIMAL
		2091
		2092	If you need to shave off some kilobytes of code at the expense of some
		2093	speed, define this symbol to C<1>. Currently only used for gcc to override
		2094	some inlining decisions, saves roughly 30% codesize of amd64.
		2095
		2096	=item EV_PID_HASHSIZE
		2097
		2098	C<ev_child> watchers use a small hash table to distribute workload by
		2099	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2100	than enough. If you need to manage thousands of children you might want to
		2101	increase this value (I<must> be a power of two).
		2102
		2103	=item EV_INOTIFY_HASHSIZE
		2104
		2105	C<ev_staz> watchers use a small hash table to distribute workload by
		2106	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2107	usually more than enough. If you need to manage thousands of C<ev_stat>
		2108	watchers you might want to increase this value (I<must> be a power of
		2109	two).
1638		2110
1639	=item EV_COMMON	2111	=item EV_COMMON
1640		2112
1641	By default, all watchers have a C<void *data> member. By redefining	2113	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	2114	this macro to a something else you can include more and other types of
…		…
1647		2119
1648	#define EV_COMMON \	2120	#define EV_COMMON \
1649	SV self; / contains this struct */ \	2121	SV self; / contains this struct */ \
1650	SV cb_sv, fh /* note no trailing ";" */	2122	SV cb_sv, fh /* note no trailing ";" */
1651		2123
1652	=item EV_CB_DECLARE(type)	2124	=item EV_CB_DECLARE (type)
1653		2125
1654	=item EV_CB_INVOKE(watcher,revents)	2126	=item EV_CB_INVOKE (watcher, revents)
1655		2127
1656	=item ev_set_cb(ev,cb)	2128	=item ev_set_cb (ev, cb)
1657		2129
1658	Can be used to change the callback member declaration in each watcher,	2130	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	2131	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	2132	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	2133	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	2134	avoid the C<struct ev_loop *> as first argument in all cases, or to use
1663	calls instead of plain function calls in C++.	2135	method calls instead of plain function calls in C++.
1664		2136
1665	=head2 EXAMPLES	2137	=head2 EXAMPLES
1666		2138
1667	For a real-world example of a program the includes libev	2139	For a real-world example of a program the includes libev
1668	verbatim, you can have a look at the EV perl module	2140	verbatim, you can have a look at the EV perl module
…		…
1673	file.	2145	file.
1674		2146
1675	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2147	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:	2148	that everybody includes and which overrides some autoconf choices:
1677		2149
1678	#define EV_USE_POLL 0	2150	#define EV_USE_POLL 0
1679	#define EV_MULTIPLICITY 0	2151	#define EV_MULTIPLICITY 0
1680	#define EV_PERIODICS 0	2152	#define EV_PERIODICS 0
1681	#define EV_CONFIG_H <config.h>	2153	#define EV_CONFIG_H <config.h>
1682		2154
1683	#include "ev++.h"	2155	#include "ev++.h"
1684		2156
1685	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2157	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1686		2158
1687	#include "rxvttoolkit.h"	2159	#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"	2160	#include "ev.c"
		2161
		2162
		2163	=head1 COMPLEXITIES
		2164
		2165	In this section the complexities of (many of) the algorithms used inside
		2166	libev will be explained. For complexity discussions about backends see the
		2167	documentation for C<ev_default_init>.
		2168
		2169	=over 4
		2170
		2171	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
		2172
		2173	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
		2174
		2175	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
		2176
		2177	=item Stopping check/prepare/idle watchers: O(1)
		2178
		2179	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2180
		2181	=item Finding the next timer per loop iteration: O(1)
		2182
		2183	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		2184
		2185	=item Activating one watcher: O(1)
		2186
		2187	=back
1693		2188
1694		2189
1695	=head1 AUTHOR	2190	=head1 AUTHOR
1696		2191
1697	Marc Lehmann <libev@schmorp.de>.	2192	Marc Lehmann <libev@schmorp.de>.

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Comparing libev/ev.pod (file contents): Revision 1.39 by root, Sat Nov 24 10:10:26 2007 UTC vs. Revision 1.61 by root, Thu Nov 29 12:21:05 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.39 by root, Sat Nov 24 10:10:26 2007 UTC vs.
Revision 1.61 by root, Thu Nov 29 12:21:05 2007 UTC