ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.35 by root, Fri Nov 23 19:35:09 2007 UTC vs.
Revision 1.58 by root, Wed Nov 28 11:31:34 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
…		…
116	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	163	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
117	recommended ones.	164	recommended ones.
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, size_t 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 and semantics are
124	realloc C function, the semantics are identical). It is used to allocate	171	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	172	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	173	allocated, the library might abort or take some potentially destructive
127	destructive action. The default is your system realloc function.	174	action. The default is your system realloc function.
128		175
129	You could override this function in high-availability programs to, say,	176	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,	177	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.	178	or even to sleep a while and retry until some memory is available.
132		179
133	Example: replace the libev allocator with one that waits a bit and then	180	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	181	retries).
135		182
136	static void *	183	static void *
137	persistent_realloc (void *ptr, long size)	184	persistent_realloc (void *ptr, size_t size)
138	{	185	{
139	for (;;)	186	for (;;)
140	{	187	{
141	void *newptr = realloc (ptr, size);	188	void *newptr = realloc (ptr, size);
142		189
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	205	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	206	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	207	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	208	(such as abort).
162		209
163	Example: do the same thing as libev does internally:	210	Example: This is basically the same thing that libev does internally, too.
164		211
165	static void	212	static void
166	fatal_error (const char *msg)	213	fatal_error (const char *msg)
167	{	214	{
168	perror (msg);	215	perror (msg);
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	361	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	362	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	363	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).	364	undefined behaviour (or a failed assertion if assertions are enabled).
318		365
319	Example: try to create a event loop that uses epoll and nothing else.	366	Example: Try to create a event loop that uses epoll and nothing else.
320		367
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	368	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
322	if (!epoller)	369	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	370	fatal ("no epoll found here, maybe it hides under your chair");
324		371
325	=item ev_default_destroy ()	372	=item ev_default_destroy ()
326		373
327	Destroys the default loop again (frees all memory and kernel state	374	Destroys the default loop again (frees all memory and kernel state
328	etc.). This stops all registered event watchers (by not touching them in	375	etc.). None of the active event watchers will be stopped in the normal
329	any way whatsoever, although you cannot rely on this :).	376	sense, so e.g. C<ev_is_active> might still return true. It is your
		377	responsibility to either stop all watchers cleanly yoursef I<before>
		378	calling this function, or cope with the fact afterwards (which is usually
		379	the easiest thing, youc na just ignore the watchers and/or C<free ()> them
		380	for example).
330		381
331	=item ev_loop_destroy (loop)	382	=item ev_loop_destroy (loop)
332		383
333	Like C<ev_default_destroy>, but destroys an event loop created by an	384	Like C<ev_default_destroy>, but destroys an event loop created by an
334	earlier call to C<ev_loop_new>.	385	earlier call to C<ev_loop_new>.
…		…
419	Signals and child watchers are implemented as I/O watchers, and will	470	Signals and child watchers are implemented as I/O watchers, and will
420	be handled here by queueing them when their watcher gets executed.	471	be handled here by queueing them when their watcher gets executed.
421	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	472	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
422	were used, return, otherwise continue with step *.	473	were used, return, otherwise continue with step *.
423		474
424	Example: queue some jobs and then loop until no events are outsanding	475	Example: Queue some jobs and then loop until no events are outsanding
425	anymore.	476	anymore.
426		477
427	... queue jobs here, make sure they register event watchers as long	478	... queue jobs here, make sure they register event watchers as long
428	... as they still have work to do (even an idle watcher will do..)	479	... as they still have work to do (even an idle watcher will do..)
429	ev_loop (my_loop, 0);	480	ev_loop (my_loop, 0);
…		…
449	visible to the libev user and should not keep C<ev_loop> from exiting if	500	visible to the libev user and should not keep C<ev_loop> from exiting if
450	no event watchers registered by it are active. It is also an excellent	501	no event watchers registered by it are active. It is also an excellent
451	way to do this for generic recurring timers or from within third-party	502	way to do this for generic recurring timers or from within third-party
452	libraries. Just remember to I<unref after start> and I<ref before stop>.	503	libraries. Just remember to I<unref after start> and I<ref before stop>.
453		504
454	Example: create a signal watcher, but keep it from keeping C<ev_loop>	505	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
455	running when nothing else is active.	506	running when nothing else is active.
456		507
457	struct dv_signal exitsig;	508	struct ev_signal exitsig;
458	ev_signal_init (&exitsig, sig_cb, SIGINT);	509	ev_signal_init (&exitsig, sig_cb, SIGINT);
459	ev_signal_start (myloop, &exitsig);	510	ev_signal_start (loop, &exitsig);
460	evf_unref (myloop);	511	evf_unref (loop);
461		512
462	Example: for some weird reason, unregister the above signal handler again.	513	Example: For some weird reason, unregister the above signal handler again.
463		514
464	ev_ref (myloop);	515	ev_ref (loop);
465	ev_signal_stop (myloop, &exitsig);	516	ev_signal_stop (loop, &exitsig);
466		517
467	=back	518	=back
		519
468		520
469	=head1 ANATOMY OF A WATCHER	521	=head1 ANATOMY OF A WATCHER
470		522
471	A watcher is a structure that you create and register to record your	523	A watcher is a structure that you create and register to record your
472	interest in some event. For instance, if you want to wait for STDIN to	524	interest in some event. For instance, if you want to wait for STDIN to
…		…
505	*) >>), and you can stop watching for events at any time by calling the	557	*) >>), and you can stop watching for events at any time by calling the
506	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.	558	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.
507		559
508	As long as your watcher is active (has been started but not stopped) you	560	As long as your watcher is active (has been started but not stopped) you
509	must not touch the values stored in it. Most specifically you must never	561	must not touch the values stored in it. Most specifically you must never
510	reinitialise it or call its set macro.	562	reinitialise it or call its C<set> macro.
511
512	You can check whether an event is active by calling the C<ev_is_active
513	(watcher *)> macro. To see whether an event is outstanding (but the
514	callback for it has not been called yet) you can use the C<ev_is_pending
515	(watcher *)> macro.
516		563
517	Each and every callback receives the event loop pointer as first, the	564	Each and every callback receives the event loop pointer as first, the
518	registered watcher structure as second, and a bitset of received events as	565	registered watcher structure as second, and a bitset of received events as
519	third argument.	566	third argument.
520		567
…		…
544	The signal specified in the C<ev_signal> watcher has been received by a thread.	591	The signal specified in the C<ev_signal> watcher has been received by a thread.
545		592
546	=item C<EV_CHILD>	593	=item C<EV_CHILD>
547		594
548	The pid specified in the C<ev_child> watcher has received a status change.	595	The pid specified in the C<ev_child> watcher has received a status change.
		596
		597	=item C<EV_STAT>
		598
		599	The path specified in the C<ev_stat> watcher changed its attributes somehow.
549		600
550	=item C<EV_IDLE>	601	=item C<EV_IDLE>
551		602
552	The C<ev_idle> watcher has determined that you have nothing better to do.	603	The C<ev_idle> watcher has determined that you have nothing better to do.
553		604
…		…
561	received events. Callbacks of both watcher types can start and stop as	612	received events. Callbacks of both watcher types can start and stop as
562	many watchers as they want, and all of them will be taken into account	613	many watchers as they want, and all of them will be taken into account
563	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	614	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
564	C<ev_loop> from blocking).	615	C<ev_loop> from blocking).
565		616
		617	=item C<EV_EMBED>
		618
		619	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		620
		621	=item C<EV_FORK>
		622
		623	The event loop has been resumed in the child process after fork (see
		624	C<ev_fork>).
		625
566	=item C<EV_ERROR>	626	=item C<EV_ERROR>
567		627
568	An unspecified error has occured, the watcher has been stopped. This might	628	An unspecified error has occured, the watcher has been stopped. This might
569	happen because the watcher could not be properly started because libev	629	happen because the watcher could not be properly started because libev
570	ran out of memory, a file descriptor was found to be closed or any other	630	ran out of memory, a file descriptor was found to be closed or any other
…		…
576	your callbacks is well-written it can just attempt the operation and cope	636	your callbacks is well-written it can just attempt the operation and cope
577	with the error from read() or write(). This will not work in multithreaded	637	with the error from read() or write(). This will not work in multithreaded
578	programs, though, so beware.	638	programs, though, so beware.
579		639
580	=back	640	=back
		641
		642	=head2 GENERIC WATCHER FUNCTIONS
		643
		644	In the following description, C<TYPE> stands for the watcher type,
		645	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.
		646
		647	=over 4
		648
		649	=item C<ev_init> (ev_TYPE *watcher, callback)
		650
		651	This macro initialises the generic portion of a watcher. The contents
		652	of the watcher object can be arbitrary (so C<malloc> will do). Only
		653	the generic parts of the watcher are initialised, you I<need> to call
		654	the type-specific C<ev_TYPE_set> macro afterwards to initialise the
		655	type-specific parts. For each type there is also a C<ev_TYPE_init> macro
		656	which rolls both calls into one.
		657
		658	You can reinitialise a watcher at any time as long as it has been stopped
		659	(or never started) and there are no pending events outstanding.
		660
		661	The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher,
		662	int revents)>.
		663
		664	=item C<ev_TYPE_set> (ev_TYPE *, [args])
		665
		666	This macro initialises the type-specific parts of a watcher. You need to
		667	call C<ev_init> at least once before you call this macro, but you can
		668	call C<ev_TYPE_set> any number of times. You must not, however, call this
		669	macro on a watcher that is active (it can be pending, however, which is a
		670	difference to the C<ev_init> macro).
		671
		672	Although some watcher types do not have type-specific arguments
		673	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
		674
		675	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
		676
		677	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
		678	calls into a single call. This is the most convinient method to initialise
		679	a watcher. The same limitations apply, of course.
		680
		681	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
		682
		683	Starts (activates) the given watcher. Only active watchers will receive
		684	events. If the watcher is already active nothing will happen.
		685
		686	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)
		687
		688	Stops the given watcher again (if active) and clears the pending
		689	status. It is possible that stopped watchers are pending (for example,
		690	non-repeating timers are being stopped when they become pending), but
		691	C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If
		692	you want to free or reuse the memory used by the watcher it is therefore a
		693	good idea to always call its C<ev_TYPE_stop> function.
		694
		695	=item bool ev_is_active (ev_TYPE *watcher)
		696
		697	Returns a true value iff the watcher is active (i.e. it has been started
		698	and not yet been stopped). As long as a watcher is active you must not modify
		699	it.
		700
		701	=item bool ev_is_pending (ev_TYPE *watcher)
		702
		703	Returns a true value iff the watcher is pending, (i.e. it has outstanding
		704	events but its callback has not yet been invoked). As long as a watcher
		705	is pending (but not active) you must not call an init function on it (but
		706	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to
		707	libev (e.g. you cnanot C<free ()> it).
		708
		709	=item callback ev_cb (ev_TYPE *watcher)
		710
		711	Returns the callback currently set on the watcher.
		712
		713	=item ev_cb_set (ev_TYPE *watcher, callback)
		714
		715	Change the callback. You can change the callback at virtually any time
		716	(modulo threads).
		717
		718	=back
		719
581		720
582	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	721	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
583		722
584	Each watcher has, by default, a member C<void *data> that you can change	723	Each watcher has, by default, a member C<void *data> that you can change
585	and read at any time, libev will completely ignore it. This can be used	724	and read at any time, libev will completely ignore it. This can be used
…		…
603	{	742	{
604	struct my_io *w = (struct my_io *)w_;	743	struct my_io *w = (struct my_io *)w_;
605	...	744	...
606	}	745	}
607		746
608	More interesting and less C-conformant ways of catsing your callback type	747	More interesting and less C-conformant ways of casting your callback type
609	have been omitted....	748	instead have been omitted.
		749
		750	Another common scenario is having some data structure with multiple
		751	watchers:
		752
		753	struct my_biggy
		754	{
		755	int some_data;
		756	ev_timer t1;
		757	ev_timer t2;
		758	}
		759
		760	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		761	you need to use C<offsetof>:
		762
		763	#include <stddef.h>
		764
		765	static void
		766	t1_cb (EV_P_ struct ev_timer *w, int revents)
		767	{
		768	struct my_biggy big = (struct my_biggy *
		769	(((char *)w) - offsetof (struct my_biggy, t1));
		770	}
		771
		772	static void
		773	t2_cb (EV_P_ struct ev_timer *w, int revents)
		774	{
		775	struct my_biggy big = (struct my_biggy *
		776	(((char *)w) - offsetof (struct my_biggy, t2));
		777	}
610		778
611		779
612	=head1 WATCHER TYPES	780	=head1 WATCHER TYPES
613		781
614	This section describes each watcher in detail, but will not repeat	782	This section describes each watcher in detail, but will not repeat
615	information given in the last section.	783	information given in the last section. Any initialisation/set macros,
		784	functions and members specific to the watcher type are explained.
616		785
		786	Members are additionally marked with either I<[read-only]>, meaning that,
		787	while the watcher is active, you can look at the member and expect some
		788	sensible content, but you must not modify it (you can modify it while the
		789	watcher is stopped to your hearts content), or I<[read-write]>, which
		790	means you can expect it to have some sensible content while the watcher
		791	is active, but you can also modify it. Modifying it may not do something
		792	sensible or take immediate effect (or do anything at all), but libev will
		793	not crash or malfunction in any way.
617		794
		795
618	=head2 C<ev_io> - is this file descriptor readable or writable	796	=head2 C<ev_io> - is this file descriptor readable or writable?
619		797
620	I/O watchers check whether a file descriptor is readable or writable	798	I/O watchers check whether a file descriptor is readable or writable
621	in each iteration of the event loop (This behaviour is called	799	in each iteration of the event loop, or, more precisely, when reading
622	level-triggering because you keep receiving events as long as the	800	would not block the process and writing would at least be able to write
623	condition persists. Remember you can stop the watcher if you don't want to	801	some data. This behaviour is called level-triggering because you keep
624	act on the event and neither want to receive future events).	802	receiving events as long as the condition persists. Remember you can stop
		803	the watcher if you don't want to act on the event and neither want to
		804	receive future events.
625		805
626	In general you can register as many read and/or write event watchers per	806	In general you can register as many read and/or write event watchers per
627	fd as you want (as long as you don't confuse yourself). Setting all file	807	fd as you want (as long as you don't confuse yourself). Setting all file
628	descriptors to non-blocking mode is also usually a good idea (but not	808	descriptors to non-blocking mode is also usually a good idea (but not
629	required if you know what you are doing).	809	required if you know what you are doing).
630		810
631	You have to be careful with dup'ed file descriptors, though. Some backends	811	You have to be careful with dup'ed file descriptors, though. Some backends
632	(the linux epoll backend is a notable example) cannot handle dup'ed file	812	(the linux epoll backend is a notable example) cannot handle dup'ed file
633	descriptors correctly if you register interest in two or more fds pointing	813	descriptors correctly if you register interest in two or more fds pointing
634	to the same underlying file/socket etc. description (that is, they share	814	to the same underlying file/socket/etc. description (that is, they share
635	the same underlying "file open").	815	the same underlying "file open").
636		816
637	If you must do this, then force the use of a known-to-be-good backend	817	If you must do this, then force the use of a known-to-be-good backend
638	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	818	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
639	C<EVBACKEND_POLL>).	819	C<EVBACKEND_POLL>).
640		820
		821	Another thing you have to watch out for is that it is quite easy to
		822	receive "spurious" readyness notifications, that is your callback might
		823	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
		824	because there is no data. Not only are some backends known to create a
		825	lot of those (for example solaris ports), it is very easy to get into
		826	this situation even with a relatively standard program structure. Thus
		827	it is best to always use non-blocking I/O: An extra C<read>(2) returning
		828	C<EAGAIN> is far preferable to a program hanging until some data arrives.
		829
		830	If you cannot run the fd in non-blocking mode (for example you should not
		831	play around with an Xlib connection), then you have to seperately re-test
		832	wether a file descriptor is really ready with a known-to-be good interface
		833	such as poll (fortunately in our Xlib example, Xlib already does this on
		834	its own, so its quite safe to use).
		835
641	=over 4	836	=over 4
642		837
643	=item ev_io_init (ev_io *, callback, int fd, int events)	838	=item ev_io_init (ev_io *, callback, int fd, int events)
644		839
645	=item ev_io_set (ev_io *, int fd, int events)	840	=item ev_io_set (ev_io *, int fd, int events)
646		841
647	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive	842	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
648	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ |	843	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
649	EV_WRITE> to receive the given events.	844	C<EV_READ | EV_WRITE> to receive the given events.
650		845
651	Please note that most of the more scalable backend mechanisms (for example	846	=item int fd [read-only]
652	epoll and solaris ports) can result in spurious readyness notifications	847
653	for file descriptors, so you practically need to use non-blocking I/O (and	848	The file descriptor being watched.
654	treat callback invocation as hint only), or retest separately with a safe	849
655	interface before doing I/O (XLib can do this), or force the use of either	850	=item int events [read-only]
656	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this	851
657	problem. Also note that it is quite easy to have your callback invoked	852	The events being watched.
658	when the readyness condition is no longer valid even when employing
659	typical ways of handling events, so its a good idea to use non-blocking
660	I/O unconditionally.
661		853
662	=back	854	=back
663		855
664	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	856	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
665	readable, but only once. Since it is likely line-buffered, you could	857	readable, but only once. Since it is likely line-buffered, you could
666	attempt to read a whole line in the callback:	858	attempt to read a whole line in the callback.
667		859
668	static void	860	static void
669	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	861	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
670	{	862	{
671	ev_io_stop (loop, w);	863	ev_io_stop (loop, w);
…		…
678	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	870	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
679	ev_io_start (loop, &stdin_readable);	871	ev_io_start (loop, &stdin_readable);
680	ev_loop (loop, 0);	872	ev_loop (loop, 0);
681		873
682		874
683	=head2 C<ev_timer> - relative and optionally recurring timeouts	875	=head2 C<ev_timer> - relative and optionally repeating timeouts
684		876
685	Timer watchers are simple relative timers that generate an event after a	877	Timer watchers are simple relative timers that generate an event after a
686	given time, and optionally repeating in regular intervals after that.	878	given time, and optionally repeating in regular intervals after that.
687		879
688	The timers are based on real time, that is, if you register an event that	880	The timers are based on real time, that is, if you register an event that
…		…
729		921
730	If the timer is repeating, either start it if necessary (with the repeat	922	If the timer is repeating, either start it if necessary (with the repeat
731	value), or reset the running timer to the repeat value.	923	value), or reset the running timer to the repeat value.
732		924
733	This sounds a bit complicated, but here is a useful and typical	925	This sounds a bit complicated, but here is a useful and typical
734	example: Imagine you have a tcp connection and you want a so-called idle	926	example: Imagine you have a tcp connection and you want a so-called
735	timeout, that is, you want to be called when there have been, say, 60	927	idle timeout, that is, you want to be called when there have been,
736	seconds of inactivity on the socket. The easiest way to do this is to	928	say, 60 seconds of inactivity on the socket. The easiest way to do
737	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each	929	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling
738	time you successfully read or write some data. If you go into an idle	930	C<ev_timer_again> each time you successfully read or write some data. If
739	state where you do not expect data to travel on the socket, you can stop	931	you go into an idle state where you do not expect data to travel on the
740	the timer, and again will automatically restart it if need be.	932	socket, you can stop the timer, and again will automatically restart it if
		933	need be.
		934
		935	You can also ignore the C<after> value and C<ev_timer_start> altogether
		936	and only ever use the C<repeat> value:
		937
		938	ev_timer_init (timer, callback, 0., 5.);
		939	ev_timer_again (loop, timer);
		940	...
		941	timer->again = 17.;
		942	ev_timer_again (loop, timer);
		943	...
		944	timer->again = 10.;
		945	ev_timer_again (loop, timer);
		946
		947	This is more efficient then stopping/starting the timer eahc time you want
		948	to modify its timeout value.
		949
		950	=item ev_tstamp repeat [read-write]
		951
		952	The current C<repeat> value. Will be used each time the watcher times out
		953	or C<ev_timer_again> is called and determines the next timeout (if any),
		954	which is also when any modifications are taken into account.
741		955
742	=back	956	=back
743		957
744	Example: create a timer that fires after 60 seconds.	958	Example: Create a timer that fires after 60 seconds.
745		959
746	static void	960	static void
747	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	961	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
748	{	962	{
749	.. one minute over, w is actually stopped right here	963	.. one minute over, w is actually stopped right here
…		…
751		965
752	struct ev_timer mytimer;	966	struct ev_timer mytimer;
753	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	967	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
754	ev_timer_start (loop, &mytimer);	968	ev_timer_start (loop, &mytimer);
755		969
756	Example: create a timeout timer that times out after 10 seconds of	970	Example: Create a timeout timer that times out after 10 seconds of
757	inactivity.	971	inactivity.
758		972
759	static void	973	static void
760	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	974	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
761	{	975	{
…		…
770	// and in some piece of code that gets executed on any "activity":	984	// and in some piece of code that gets executed on any "activity":
771	// reset the timeout to start ticking again at 10 seconds	985	// reset the timeout to start ticking again at 10 seconds
772	ev_timer_again (&mytimer);	986	ev_timer_again (&mytimer);
773		987
774		988
775	=head2 C<ev_periodic> - to cron or not to cron	989	=head2 C<ev_periodic> - to cron or not to cron?
776		990
777	Periodic watchers are also timers of a kind, but they are very versatile	991	Periodic watchers are also timers of a kind, but they are very versatile
778	(and unfortunately a bit complex).	992	(and unfortunately a bit complex).
779		993
780	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	994	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
781	but on wallclock time (absolute time). You can tell a periodic watcher	995	but on wallclock time (absolute time). You can tell a periodic watcher
782	to trigger "at" some specific point in time. For example, if you tell a	996	to trigger "at" some specific point in time. For example, if you tell a
783	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	997	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
784	+ 10.>) and then reset your system clock to the last year, then it will	998	+ 10.>) and then reset your system clock to the last year, then it will
785	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	999	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
786	roughly 10 seconds later and of course not if you reset your system time	1000	roughly 10 seconds later and of course not if you reset your system time
787	again).	1001	again).
788		1002
…		…
872	Simply stops and restarts the periodic watcher again. This is only useful	1086	Simply stops and restarts the periodic watcher again. This is only useful
873	when you changed some parameters or the reschedule callback would return	1087	when you changed some parameters or the reschedule callback would return
874	a different time than the last time it was called (e.g. in a crond like	1088	a different time than the last time it was called (e.g. in a crond like
875	program when the crontabs have changed).	1089	program when the crontabs have changed).
876		1090
		1091	=item ev_tstamp interval [read-write]
		1092
		1093	The current interval value. Can be modified any time, but changes only
		1094	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1095	called.
		1096
		1097	=item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]
		1098
		1099	The current reschedule callback, or C<0>, if this functionality is
		1100	switched off. Can be changed any time, but changes only take effect when
		1101	the periodic timer fires or C<ev_periodic_again> is being called.
		1102
877	=back	1103	=back
878		1104
879	Example: call a callback every hour, or, more precisely, whenever the	1105	Example: Call a callback every hour, or, more precisely, whenever the
880	system clock is divisible by 3600. The callback invocation times have	1106	system clock is divisible by 3600. The callback invocation times have
881	potentially a lot of jittering, but good long-term stability.	1107	potentially a lot of jittering, but good long-term stability.
882		1108
883	static void	1109	static void
884	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1110	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
…		…
888		1114
889	struct ev_periodic hourly_tick;	1115	struct ev_periodic hourly_tick;
890	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1116	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
891	ev_periodic_start (loop, &hourly_tick);	1117	ev_periodic_start (loop, &hourly_tick);
892		1118
893	Example: the same as above, but use a reschedule callback to do it:	1119	Example: The same as above, but use a reschedule callback to do it:
894		1120
895	#include <math.h>	1121	#include <math.h>
896		1122
897	static ev_tstamp	1123	static ev_tstamp
898	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1124	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
900	return fmod (now, 3600.) + 3600.;	1126	return fmod (now, 3600.) + 3600.;
901	}	1127	}
902		1128
903	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1129	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
904		1130
905	Example: call a callback every hour, starting now:	1131	Example: Call a callback every hour, starting now:
906		1132
907	struct ev_periodic hourly_tick;	1133	struct ev_periodic hourly_tick;
908	ev_periodic_init (&hourly_tick, clock_cb,	1134	ev_periodic_init (&hourly_tick, clock_cb,
909	fmod (ev_now (loop), 3600.), 3600., 0);	1135	fmod (ev_now (loop), 3600.), 3600., 0);
910	ev_periodic_start (loop, &hourly_tick);	1136	ev_periodic_start (loop, &hourly_tick);
911		1137
912		1138
913	=head2 C<ev_signal> - signal me when a signal gets signalled	1139	=head2 C<ev_signal> - signal me when a signal gets signalled!
914		1140
915	Signal watchers will trigger an event when the process receives a specific	1141	Signal watchers will trigger an event when the process receives a specific
916	signal one or more times. Even though signals are very asynchronous, libev	1142	signal one or more times. Even though signals are very asynchronous, libev
917	will try it's best to deliver signals synchronously, i.e. as part of the	1143	will try it's best to deliver signals synchronously, i.e. as part of the
918	normal event processing, like any other event.	1144	normal event processing, like any other event.
…		…
931	=item ev_signal_set (ev_signal *, int signum)	1157	=item ev_signal_set (ev_signal *, int signum)
932		1158
933	Configures the watcher to trigger on the given signal number (usually one	1159	Configures the watcher to trigger on the given signal number (usually one
934	of the C<SIGxxx> constants).	1160	of the C<SIGxxx> constants).
935		1161
		1162	=item int signum [read-only]
		1163
		1164	The signal the watcher watches out for.
		1165
936	=back	1166	=back
937		1167
938		1168
939	=head2 C<ev_child> - wait for pid status changes	1169	=head2 C<ev_child> - watch out for process status changes
940		1170
941	Child watchers trigger when your process receives a SIGCHLD in response to	1171	Child watchers trigger when your process receives a SIGCHLD in response to
942	some child status changes (most typically when a child of yours dies).	1172	some child status changes (most typically when a child of yours dies).
943		1173
944	=over 4	1174	=over 4
…		…
952	at the C<rstatus> member of the C<ev_child> watcher structure to see	1182	at the C<rstatus> member of the C<ev_child> watcher structure to see
953	the status word (use the macros from C<sys/wait.h> and see your systems	1183	the status word (use the macros from C<sys/wait.h> and see your systems
954	C<waitpid> documentation). The C<rpid> member contains the pid of the	1184	C<waitpid> documentation). The C<rpid> member contains the pid of the
955	process causing the status change.	1185	process causing the status change.
956		1186
		1187	=item int pid [read-only]
		1188
		1189	The process id this watcher watches out for, or C<0>, meaning any process id.
		1190
		1191	=item int rpid [read-write]
		1192
		1193	The process id that detected a status change.
		1194
		1195	=item int rstatus [read-write]
		1196
		1197	The process exit/trace status caused by C<rpid> (see your systems
		1198	C<waitpid> and C<sys/wait.h> documentation for details).
		1199
957	=back	1200	=back
958		1201
959	Example: try to exit cleanly on SIGINT and SIGTERM.	1202	Example: Try to exit cleanly on SIGINT and SIGTERM.
960		1203
961	static void	1204	static void
962	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1205	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
963	{	1206	{
964	ev_unloop (loop, EVUNLOOP_ALL);	1207	ev_unloop (loop, EVUNLOOP_ALL);
…		…
967	struct ev_signal signal_watcher;	1210	struct ev_signal signal_watcher;
968	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1211	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
969	ev_signal_start (loop, &sigint_cb);	1212	ev_signal_start (loop, &sigint_cb);
970		1213
971		1214
		1215	=head2 C<ev_stat> - did the file attributes just change?
		1216
		1217	This watches a filesystem path for attribute changes. That is, it calls
		1218	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1219	compared to the last time, invoking the callback if it did.
		1220
		1221	The path does not need to exist: changing from "path exists" to "path does
		1222	not exist" is a status change like any other. The condition "path does
		1223	not exist" is signified by the C<st_nlink> field being zero (which is
		1224	otherwise always forced to be at least one) and all the other fields of
		1225	the stat buffer having unspecified contents.
		1226
		1227	Since there is no standard to do this, the portable implementation simply
		1228	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1229	can specify a recommended polling interval for this case. If you specify
		1230	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1231	unspecified default> value will be used (which you can expect to be around
		1232	five seconds, although this might change dynamically). Libev will also
		1233	impose a minimum interval which is currently around C<0.1>, but thats
		1234	usually overkill.
		1235
		1236	This watcher type is not meant for massive numbers of stat watchers,
		1237	as even with OS-supported change notifications, this can be
		1238	resource-intensive.
		1239
		1240	At the time of this writing, only the Linux inotify interface is
		1241	implemented (implementing kqueue support is left as an exercise for the
		1242	reader). Inotify will be used to give hints only and should not change the
		1243	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1244	to fall back to regular polling again even with inotify, but changes are
		1245	usually detected immediately, and if the file exists there will be no
		1246	polling.
		1247
		1248	=over 4
		1249
		1250	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
		1251
		1252	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)
		1253
		1254	Configures the watcher to wait for status changes of the given
		1255	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1256	be detected and should normally be specified as C<0> to let libev choose
		1257	a suitable value. The memory pointed to by C<path> must point to the same
		1258	path for as long as the watcher is active.
		1259
		1260	The callback will be receive C<EV_STAT> when a change was detected,
		1261	relative to the attributes at the time the watcher was started (or the
		1262	last change was detected).
		1263
		1264	=item ev_stat_stat (ev_stat *)
		1265
		1266	Updates the stat buffer immediately with new values. If you change the
		1267	watched path in your callback, you could call this fucntion to avoid
		1268	detecting this change (while introducing a race condition). Can also be
		1269	useful simply to find out the new values.
		1270
		1271	=item ev_statdata attr [read-only]
		1272
		1273	The most-recently detected attributes of the file. Although the type is of
		1274	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1275	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1276	was some error while C<stat>ing the file.
		1277
		1278	=item ev_statdata prev [read-only]
		1279
		1280	The previous attributes of the file. The callback gets invoked whenever
		1281	C<prev> != C<attr>.
		1282
		1283	=item ev_tstamp interval [read-only]
		1284
		1285	The specified interval.
		1286
		1287	=item const char *path [read-only]
		1288
		1289	The filesystem path that is being watched.
		1290
		1291	=back
		1292
		1293	Example: Watch C</etc/passwd> for attribute changes.
		1294
		1295	static void
		1296	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
		1297	{
		1298	/* /etc/passwd changed in some way */
		1299	if (w->attr.st_nlink)
		1300	{
		1301	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1302	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1303	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1304	}
		1305	else
		1306	/* you shalt not abuse printf for puts */
		1307	puts ("wow, /etc/passwd is not there, expect problems. "
		1308	"if this is windows, they already arrived\n");
		1309	}
		1310
		1311	...
		1312	ev_stat passwd;
		1313
		1314	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1315	ev_stat_start (loop, &passwd);
		1316
		1317
972	=head2 C<ev_idle> - when you've got nothing better to do	1318	=head2 C<ev_idle> - when you've got nothing better to do...
973		1319
974	Idle watchers trigger events when there are no other events are pending	1320	Idle watchers trigger events when there are no other events are pending
975	(prepare, check and other idle watchers do not count). That is, as long	1321	(prepare, check and other idle watchers do not count). That is, as long
976	as your process is busy handling sockets or timeouts (or even signals,	1322	as your process is busy handling sockets or timeouts (or even signals,
977	imagine) it will not be triggered. But when your process is idle all idle	1323	imagine) it will not be triggered. But when your process is idle all idle
…		…
995	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1341	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
996	believe me.	1342	believe me.
997		1343
998	=back	1344	=back
999		1345
1000	Example: dynamically allocate an C<ev_idle>, start it, and in the	1346	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1001	callback, free it. Alos, use no error checking, as usual.	1347	callback, free it. Also, use no error checking, as usual.
1002		1348
1003	static void	1349	static void
1004	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1350	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1005	{	1351	{
1006	free (w);	1352	free (w);
…		…
1011	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1357	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1012	ev_idle_init (idle_watcher, idle_cb);	1358	ev_idle_init (idle_watcher, idle_cb);
1013	ev_idle_start (loop, idle_cb);	1359	ev_idle_start (loop, idle_cb);
1014		1360
1015		1361
1016	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	1362	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1017		1363
1018	Prepare and check watchers are usually (but not always) used in tandem:	1364	Prepare and check watchers are usually (but not always) used in tandem:
1019	prepare watchers get invoked before the process blocks and check watchers	1365	prepare watchers get invoked before the process blocks and check watchers
1020	afterwards.	1366	afterwards.
1021		1367
		1368	You I<must not> call C<ev_loop> or similar functions that enter
		1369	the current event loop from either C<ev_prepare> or C<ev_check>
		1370	watchers. Other loops than the current one are fine, however. The
		1371	rationale behind this is that you do not need to check for recursion in
		1372	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
		1373	C<ev_check> so if you have one watcher of each kind they will always be
		1374	called in pairs bracketing the blocking call.
		1375
1022	Their main purpose is to integrate other event mechanisms into libev and	1376	Their main purpose is to integrate other event mechanisms into libev and
1023	their use is somewhat advanced. This could be used, for example, to track	1377	their use is somewhat advanced. This could be used, for example, to track
1024	variable changes, implement your own watchers, integrate net-snmp or a	1378	variable changes, implement your own watchers, integrate net-snmp or a
1025	coroutine library and lots more.	1379	coroutine library and lots more. They are also occasionally useful if
		1380	you cache some data and want to flush it before blocking (for example,
		1381	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
		1382	watcher).
1026		1383
1027	This is done by examining in each prepare call which file descriptors need	1384	This is done by examining in each prepare call which file descriptors need
1028	to be watched by the other library, registering C<ev_io> watchers for	1385	to be watched by the other library, registering C<ev_io> watchers for
1029	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1386	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1030	provide just this functionality). Then, in the check watcher you check for	1387	provide just this functionality). Then, in the check watcher you check for
…		…
1052	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1409	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1053	macros, but using them is utterly, utterly and completely pointless.	1410	macros, but using them is utterly, utterly and completely pointless.
1054		1411
1055	=back	1412	=back
1056		1413
1057	Example: *TODO*.	1414	Example: To include a library such as adns, you would add IO watchers
		1415	and a timeout watcher in a prepare handler, as required by libadns, and
		1416	in a check watcher, destroy them and call into libadns. What follows is
		1417	pseudo-code only of course:
1058		1418
		1419	static ev_io iow [nfd];
		1420	static ev_timer tw;
1059		1421
		1422	static void
		1423	io_cb (ev_loop *loop, ev_io *w, int revents)
		1424	{
		1425	// set the relevant poll flags
		1426	// could also call adns_processreadable etc. here
		1427	struct pollfd *fd = (struct pollfd *)w->data;
		1428	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1429	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1430	}
		1431
		1432	// create io watchers for each fd and a timer before blocking
		1433	static void
		1434	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
		1435	{
		1436	int timeout = 3600000;truct pollfd fds [nfd];
		1437	// actual code will need to loop here and realloc etc.
		1438	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1439
		1440	/* the callback is illegal, but won't be called as we stop during check */
		1441	ev_timer_init (&tw, 0, timeout * 1e-3);
		1442	ev_timer_start (loop, &tw);
		1443
		1444	// create on ev_io per pollfd
		1445	for (int i = 0; i < nfd; ++i)
		1446	{
		1447	ev_io_init (iow + i, io_cb, fds [i].fd,
		1448	((fds [i].events & POLLIN ? EV_READ : 0)
		1449	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1450
		1451	fds [i].revents = 0;
		1452	iow [i].data = fds + i;
		1453	ev_io_start (loop, iow + i);
		1454	}
		1455	}
		1456
		1457	// stop all watchers after blocking
		1458	static void
		1459	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
		1460	{
		1461	ev_timer_stop (loop, &tw);
		1462
		1463	for (int i = 0; i < nfd; ++i)
		1464	ev_io_stop (loop, iow + i);
		1465
		1466	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1467	}
		1468
		1469
1060	=head2 C<ev_embed> - when one backend isn't enough	1470	=head2 C<ev_embed> - when one backend isn't enough...
1061		1471
1062	This is a rather advanced watcher type that lets you embed one event loop	1472	This is a rather advanced watcher type that lets you embed one event loop
1063	into another.	1473	into another (currently only C<ev_io> events are supported in the embedded
		1474	loop, other types of watchers might be handled in a delayed or incorrect
		1475	fashion and must not be used).
1064		1476
1065	There are primarily two reasons you would want that: work around bugs and	1477	There are primarily two reasons you would want that: work around bugs and
1066	prioritise I/O.	1478	prioritise I/O.
1067		1479
1068	As an example for a bug workaround, the kqueue backend might only support	1480	As an example for a bug workaround, the kqueue backend might only support
…		…
1076	As for prioritising I/O: rarely you have the case where some fds have	1488	As for prioritising I/O: rarely you have the case where some fds have
1077	to be watched and handled very quickly (with low latency), and even	1489	to be watched and handled very quickly (with low latency), and even
1078	priorities and idle watchers might have too much overhead. In this case	1490	priorities and idle watchers might have too much overhead. In this case
1079	you would put all the high priority stuff in one loop and all the rest in	1491	you would put all the high priority stuff in one loop and all the rest in
1080	a second one, and embed the second one in the first.	1492	a second one, and embed the second one in the first.
		1493
		1494	As long as the watcher is active, the callback will be invoked every time
		1495	there might be events pending in the embedded loop. The callback must then
		1496	call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke
		1497	their callbacks (you could also start an idle watcher to give the embedded
		1498	loop strictly lower priority for example). You can also set the callback
		1499	to C<0>, in which case the embed watcher will automatically execute the
		1500	embedded loop sweep.
1081		1501
1082	As long as the watcher is started it will automatically handle events. The	1502	As long as the watcher is started it will automatically handle events. The
1083	callback will be invoked whenever some events have been handled. You can	1503	callback will be invoked whenever some events have been handled. You can
1084	set the callback to C<0> to avoid having to specify one if you are not	1504	set the callback to C<0> to avoid having to specify one if you are not
1085	interested in that.	1505	interested in that.
…		…
1117	else	1537	else
1118	loop_lo = loop_hi;	1538	loop_lo = loop_hi;
1119		1539
1120	=over 4	1540	=over 4
1121		1541
1122	=item ev_embed_init (ev_embed *, callback, struct ev_loop *loop)	1542	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
1123		1543
1124	=item ev_embed_set (ev_embed *, callback, struct ev_loop *loop)	1544	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)
1125		1545
1126	Configures the watcher to embed the given loop, which must be embeddable.	1546	Configures the watcher to embed the given loop, which must be
		1547	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
		1548	invoked automatically, otherwise it is the responsibility of the callback
		1549	to invoke it (it will continue to be called until the sweep has been done,
		1550	if you do not want thta, you need to temporarily stop the embed watcher).
		1551
		1552	=item ev_embed_sweep (loop, ev_embed *)
		1553
		1554	Make a single, non-blocking sweep over the embedded loop. This works
		1555	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
		1556	apropriate way for embedded loops.
		1557
		1558	=item struct ev_loop *loop [read-only]
		1559
		1560	The embedded event loop.
		1561
		1562	=back
		1563
		1564
		1565	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1566
		1567	Fork watchers are called when a C<fork ()> was detected (usually because
		1568	whoever is a good citizen cared to tell libev about it by calling
		1569	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1570	event loop blocks next and before C<ev_check> watchers are being called,
		1571	and only in the child after the fork. If whoever good citizen calling
		1572	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1573	handlers will be invoked, too, of course.
		1574
		1575	=over 4
		1576
		1577	=item ev_fork_init (ev_signal *, callback)
		1578
		1579	Initialises and configures the fork watcher - it has no parameters of any
		1580	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1581	believe me.
1127		1582
1128	=back	1583	=back
1129		1584
1130		1585
1131	=head1 OTHER FUNCTIONS	1586	=head1 OTHER FUNCTIONS
…		…
1164	/* stdin might have data for us, joy! */;	1619	/* stdin might have data for us, joy! */;
1165	}	1620	}
1166		1621
1167	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	1622	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
1168		1623
1169	=item ev_feed_event (loop, watcher, int events)	1624	=item ev_feed_event (ev_loop *, watcher *, int revents)
1170		1625
1171	Feeds the given event set into the event loop, as if the specified event	1626	Feeds the given event set into the event loop, as if the specified event
1172	had happened for the specified watcher (which must be a pointer to an	1627	had happened for the specified watcher (which must be a pointer to an
1173	initialised but not necessarily started event watcher).	1628	initialised but not necessarily started event watcher).
1174		1629
1175	=item ev_feed_fd_event (loop, int fd, int revents)	1630	=item ev_feed_fd_event (ev_loop *, int fd, int revents)
1176		1631
1177	Feed an event on the given fd, as if a file descriptor backend detected	1632	Feed an event on the given fd, as if a file descriptor backend detected
1178	the given events it.	1633	the given events it.
1179		1634
1180	=item ev_feed_signal_event (loop, int signum)	1635	=item ev_feed_signal_event (ev_loop *loop, int signum)
1181		1636
1182	Feed an event as if the given signal occured (loop must be the default loop!).	1637	Feed an event as if the given signal occured (C<loop> must be the default
		1638	loop!).
1183		1639
1184	=back	1640	=back
1185		1641
1186		1642
1187	=head1 LIBEVENT EMULATION	1643	=head1 LIBEVENT EMULATION
…		…
1211		1667
1212	=back	1668	=back
1213		1669
1214	=head1 C++ SUPPORT	1670	=head1 C++ SUPPORT
1215		1671
1216	TBD.	1672	Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1673	you to use some convinience methods to start/stop watchers and also change
		1674	the callback model to a model using method callbacks on objects.
		1675
		1676	To use it,
		1677
		1678	#include <ev++.h>
		1679
		1680	(it is not installed by default). This automatically includes F<ev.h>
		1681	and puts all of its definitions (many of them macros) into the global
		1682	namespace. All C++ specific things are put into the C<ev> namespace.
		1683
		1684	It should support all the same embedding options as F<ev.h>, most notably
		1685	C<EV_MULTIPLICITY>.
		1686
		1687	Here is a list of things available in the C<ev> namespace:
		1688
		1689	=over 4
		1690
		1691	=item C<ev::READ>, C<ev::WRITE> etc.
		1692
		1693	These are just enum values with the same values as the C<EV_READ> etc.
		1694	macros from F<ev.h>.
		1695
		1696	=item C<ev::tstamp>, C<ev::now>
		1697
		1698	Aliases to the same types/functions as with the C<ev_> prefix.
		1699
		1700	=item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc.
		1701
		1702	For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of
		1703	the same name in the C<ev> namespace, with the exception of C<ev_signal>
		1704	which is called C<ev::sig> to avoid clashes with the C<signal> macro
		1705	defines by many implementations.
		1706
		1707	All of those classes have these methods:
		1708
		1709	=over 4
		1710
		1711	=item ev::TYPE::TYPE (object *, object::method *)
		1712
		1713	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)
		1714
		1715	=item ev::TYPE::~TYPE
		1716
		1717	The constructor takes a pointer to an object and a method pointer to
		1718	the event handler callback to call in this class. The constructor calls
		1719	C<ev_init> for you, which means you have to call the C<set> method
		1720	before starting it. If you do not specify a loop then the constructor
		1721	automatically associates the default loop with this watcher.
		1722
		1723	The destructor automatically stops the watcher if it is active.
		1724
		1725	=item w->set (struct ev_loop *)
		1726
		1727	Associates a different C<struct ev_loop> with this watcher. You can only
		1728	do this when the watcher is inactive (and not pending either).
		1729
		1730	=item w->set ([args])
		1731
		1732	Basically the same as C<ev_TYPE_set>, with the same args. Must be
		1733	called at least once. Unlike the C counterpart, an active watcher gets
		1734	automatically stopped and restarted.
		1735
		1736	=item w->start ()
		1737
		1738	Starts the watcher. Note that there is no C<loop> argument as the
		1739	constructor already takes the loop.
		1740
		1741	=item w->stop ()
		1742
		1743	Stops the watcher if it is active. Again, no C<loop> argument.
		1744
		1745	=item w->again () C<ev::timer>, C<ev::periodic> only
		1746
		1747	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
		1748	C<ev_TYPE_again> function.
		1749
		1750	=item w->sweep () C<ev::embed> only
		1751
		1752	Invokes C<ev_embed_sweep>.
		1753
		1754	=item w->update () C<ev::stat> only
		1755
		1756	Invokes C<ev_stat_stat>.
		1757
		1758	=back
		1759
		1760	=back
		1761
		1762	Example: Define a class with an IO and idle watcher, start one of them in
		1763	the constructor.
		1764
		1765	class myclass
		1766	{
		1767	ev_io io; void io_cb (ev::io &w, int revents);
		1768	ev_idle idle void idle_cb (ev::idle &w, int revents);
		1769
		1770	myclass ();
		1771	}
		1772
		1773	myclass::myclass (int fd)
		1774	: io (this, &myclass::io_cb),
		1775	idle (this, &myclass::idle_cb)
		1776	{
		1777	io.start (fd, ev::READ);
		1778	}
		1779
		1780
		1781	=head1 MACRO MAGIC
		1782
		1783	Libev can be compiled with a variety of options, the most fundemantal is
		1784	C<EV_MULTIPLICITY>. This option determines wether (most) functions and
		1785	callbacks have an initial C<struct ev_loop *> argument.
		1786
		1787	To make it easier to write programs that cope with either variant, the
		1788	following macros are defined:
		1789
		1790	=over 4
		1791
		1792	=item C<EV_A>, C<EV_A_>
		1793
		1794	This provides the loop I<argument> for functions, if one is required ("ev
		1795	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1796	C<EV_A_> is used when other arguments are following. Example:
		1797
		1798	ev_unref (EV_A);
		1799	ev_timer_add (EV_A_ watcher);
		1800	ev_loop (EV_A_ 0);
		1801
		1802	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1803	which is often provided by the following macro.
		1804
		1805	=item C<EV_P>, C<EV_P_>
		1806
		1807	This provides the loop I<parameter> for functions, if one is required ("ev
		1808	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1809	C<EV_P_> is used when other parameters are following. Example:
		1810
		1811	// this is how ev_unref is being declared
		1812	static void ev_unref (EV_P);
		1813
		1814	// this is how you can declare your typical callback
		1815	static void cb (EV_P_ ev_timer *w, int revents)
		1816
		1817	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1818	suitable for use with C<EV_A>.
		1819
		1820	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1821
		1822	Similar to the other two macros, this gives you the value of the default
		1823	loop, if multiple loops are supported ("ev loop default").
		1824
		1825	=back
		1826
		1827	Example: Declare and initialise a check watcher, working regardless of
		1828	wether multiple loops are supported or not.
		1829
		1830	static void
		1831	check_cb (EV_P_ ev_timer *w, int revents)
		1832	{
		1833	ev_check_stop (EV_A_ w);
		1834	}
		1835
		1836	ev_check check;
		1837	ev_check_init (&check, check_cb);
		1838	ev_check_start (EV_DEFAULT_ &check);
		1839	ev_loop (EV_DEFAULT_ 0);
		1840
		1841
		1842	=head1 EMBEDDING
		1843
		1844	Libev can (and often is) directly embedded into host
		1845	applications. Examples of applications that embed it include the Deliantra
		1846	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		1847	and rxvt-unicode.
		1848
		1849	The goal is to enable you to just copy the neecssary files into your
		1850	source directory without having to change even a single line in them, so
		1851	you can easily upgrade by simply copying (or having a checked-out copy of
		1852	libev somewhere in your source tree).
		1853
		1854	=head2 FILESETS
		1855
		1856	Depending on what features you need you need to include one or more sets of files
		1857	in your app.
		1858
		1859	=head3 CORE EVENT LOOP
		1860
		1861	To include only the libev core (all the C<ev_*> functions), with manual
		1862	configuration (no autoconf):
		1863
		1864	#define EV_STANDALONE 1
		1865	#include "ev.c"
		1866
		1867	This will automatically include F<ev.h>, too, and should be done in a
		1868	single C source file only to provide the function implementations. To use
		1869	it, do the same for F<ev.h> in all files wishing to use this API (best
		1870	done by writing a wrapper around F<ev.h> that you can include instead and
		1871	where you can put other configuration options):
		1872
		1873	#define EV_STANDALONE 1
		1874	#include "ev.h"
		1875
		1876	Both header files and implementation files can be compiled with a C++
		1877	compiler (at least, thats a stated goal, and breakage will be treated
		1878	as a bug).
		1879
		1880	You need the following files in your source tree, or in a directory
		1881	in your include path (e.g. in libev/ when using -Ilibev):
		1882
		1883	ev.h
		1884	ev.c
		1885	ev_vars.h
		1886	ev_wrap.h
		1887
		1888	ev_win32.c required on win32 platforms only
		1889
		1890	ev_select.c only when select backend is enabled (which is by default)
		1891	ev_poll.c only when poll backend is enabled (disabled by default)
		1892	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1893	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1894	ev_port.c only when the solaris port backend is enabled (disabled by default)
		1895
		1896	F<ev.c> includes the backend files directly when enabled, so you only need
		1897	to compile this single file.
		1898
		1899	=head3 LIBEVENT COMPATIBILITY API
		1900
		1901	To include the libevent compatibility API, also include:
		1902
		1903	#include "event.c"
		1904
		1905	in the file including F<ev.c>, and:
		1906
		1907	#include "event.h"
		1908
		1909	in the files that want to use the libevent API. This also includes F<ev.h>.
		1910
		1911	You need the following additional files for this:
		1912
		1913	event.h
		1914	event.c
		1915
		1916	=head3 AUTOCONF SUPPORT
		1917
		1918	Instead of using C<EV_STANDALONE=1> and providing your config in
		1919	whatever way you want, you can also C<m4_include([libev.m4])> in your
		1920	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
		1921	include F<config.h> and configure itself accordingly.
		1922
		1923	For this of course you need the m4 file:
		1924
		1925	libev.m4
		1926
		1927	=head2 PREPROCESSOR SYMBOLS/MACROS
		1928
		1929	Libev can be configured via a variety of preprocessor symbols you have to define
		1930	before including any of its files. The default is not to build for multiplicity
		1931	and only include the select backend.
		1932
		1933	=over 4
		1934
		1935	=item EV_STANDALONE
		1936
		1937	Must always be C<1> if you do not use autoconf configuration, which
		1938	keeps libev from including F<config.h>, and it also defines dummy
		1939	implementations for some libevent functions (such as logging, which is not
		1940	supported). It will also not define any of the structs usually found in
		1941	F<event.h> that are not directly supported by the libev core alone.
		1942
		1943	=item EV_USE_MONOTONIC
		1944
		1945	If defined to be C<1>, libev will try to detect the availability of the
		1946	monotonic clock option at both compiletime and runtime. Otherwise no use
		1947	of the monotonic clock option will be attempted. If you enable this, you
		1948	usually have to link against librt or something similar. Enabling it when
		1949	the functionality isn't available is safe, though, althoguh you have
		1950	to make sure you link against any libraries where the C<clock_gettime>
		1951	function is hiding in (often F<-lrt>).
		1952
		1953	=item EV_USE_REALTIME
		1954
		1955	If defined to be C<1>, libev will try to detect the availability of the
		1956	realtime clock option at compiletime (and assume its availability at
		1957	runtime if successful). Otherwise no use of the realtime clock option will
		1958	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
		1959	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries
		1960	in the description of C<EV_USE_MONOTONIC>, though.
		1961
		1962	=item EV_USE_SELECT
		1963
		1964	If undefined or defined to be C<1>, libev will compile in support for the
		1965	C<select>(2) backend. No attempt at autodetection will be done: if no
		1966	other method takes over, select will be it. Otherwise the select backend
		1967	will not be compiled in.
		1968
		1969	=item EV_SELECT_USE_FD_SET
		1970
		1971	If defined to C<1>, then the select backend will use the system C<fd_set>
		1972	structure. This is useful if libev doesn't compile due to a missing
		1973	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on
		1974	exotic systems. This usually limits the range of file descriptors to some
		1975	low limit such as 1024 or might have other limitations (winsocket only
		1976	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
		1977	influence the size of the C<fd_set> used.
		1978
		1979	=item EV_SELECT_IS_WINSOCKET
		1980
		1981	When defined to C<1>, the select backend will assume that
		1982	select/socket/connect etc. don't understand file descriptors but
		1983	wants osf handles on win32 (this is the case when the select to
		1984	be used is the winsock select). This means that it will call
		1985	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
		1986	it is assumed that all these functions actually work on fds, even
		1987	on win32. Should not be defined on non-win32 platforms.
		1988
		1989	=item EV_USE_POLL
		1990
		1991	If defined to be C<1>, libev will compile in support for the C<poll>(2)
		1992	backend. Otherwise it will be enabled on non-win32 platforms. It
		1993	takes precedence over select.
		1994
		1995	=item EV_USE_EPOLL
		1996
		1997	If defined to be C<1>, libev will compile in support for the Linux
		1998	C<epoll>(7) backend. Its availability will be detected at runtime,
		1999	otherwise another method will be used as fallback. This is the
		2000	preferred backend for GNU/Linux systems.
		2001
		2002	=item EV_USE_KQUEUE
		2003
		2004	If defined to be C<1>, libev will compile in support for the BSD style
		2005	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
		2006	otherwise another method will be used as fallback. This is the preferred
		2007	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		2008	supports some types of fds correctly (the only platform we found that
		2009	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		2010	not be used unless explicitly requested. The best way to use it is to find
		2011	out whether kqueue supports your type of fd properly and use an embedded
		2012	kqueue loop.
		2013
		2014	=item EV_USE_PORT
		2015
		2016	If defined to be C<1>, libev will compile in support for the Solaris
		2017	10 port style backend. Its availability will be detected at runtime,
		2018	otherwise another method will be used as fallback. This is the preferred
		2019	backend for Solaris 10 systems.
		2020
		2021	=item EV_USE_DEVPOLL
		2022
		2023	reserved for future expansion, works like the USE symbols above.
		2024
		2025	=item EV_USE_INOTIFY
		2026
		2027	If defined to be C<1>, libev will compile in support for the Linux inotify
		2028	interface to speed up C<ev_stat> watchers. Its actual availability will
		2029	be detected at runtime.
		2030
		2031	=item EV_H
		2032
		2033	The name of the F<ev.h> header file used to include it. The default if
		2034	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
		2035	can be used to virtually rename the F<ev.h> header file in case of conflicts.
		2036
		2037	=item EV_CONFIG_H
		2038
		2039	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
		2040	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
		2041	C<EV_H>, above.
		2042
		2043	=item EV_EVENT_H
		2044
		2045	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
		2046	of how the F<event.h> header can be found.
		2047
		2048	=item EV_PROTOTYPES
		2049
		2050	If defined to be C<0>, then F<ev.h> will not define any function
		2051	prototypes, but still define all the structs and other symbols. This is
		2052	occasionally useful if you want to provide your own wrapper functions
		2053	around libev functions.
		2054
		2055	=item EV_MULTIPLICITY
		2056
		2057	If undefined or defined to C<1>, then all event-loop-specific functions
		2058	will have the C<struct ev_loop *> as first argument, and you can create
		2059	additional independent event loops. Otherwise there will be no support
		2060	for multiple event loops and there is no first event loop pointer
		2061	argument. Instead, all functions act on the single default loop.
		2062
		2063	=item EV_PERIODIC_ENABLE
		2064
		2065	If undefined or defined to be C<1>, then periodic timers are supported. If
		2066	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2067	code.
		2068
		2069	=item EV_EMBED_ENABLE
		2070
		2071	If undefined or defined to be C<1>, then embed watchers are supported. If
		2072	defined to be C<0>, then they are not.
		2073
		2074	=item EV_STAT_ENABLE
		2075
		2076	If undefined or defined to be C<1>, then stat watchers are supported. If
		2077	defined to be C<0>, then they are not.
		2078
		2079	=item EV_FORK_ENABLE
		2080
		2081	If undefined or defined to be C<1>, then fork watchers are supported. If
		2082	defined to be C<0>, then they are not.
		2083
		2084	=item EV_MINIMAL
		2085
		2086	If you need to shave off some kilobytes of code at the expense of some
		2087	speed, define this symbol to C<1>. Currently only used for gcc to override
		2088	some inlining decisions, saves roughly 30% codesize of amd64.
		2089
		2090	=item EV_PID_HASHSIZE
		2091
		2092	C<ev_child> watchers use a small hash table to distribute workload by
		2093	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2094	than enough. If you need to manage thousands of children you might want to
		2095	increase this value (I<must> be a power of two).
		2096
		2097	=item EV_INOTIFY_HASHSIZE
		2098
		2099	C<ev_staz> watchers use a small hash table to distribute workload by
		2100	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2101	usually more than enough. If you need to manage thousands of C<ev_stat>
		2102	watchers you might want to increase this value (I<must> be a power of
		2103	two).
		2104
		2105	=item EV_COMMON
		2106
		2107	By default, all watchers have a C<void *data> member. By redefining
		2108	this macro to a something else you can include more and other types of
		2109	members. You have to define it each time you include one of the files,
		2110	though, and it must be identical each time.
		2111
		2112	For example, the perl EV module uses something like this:
		2113
		2114	#define EV_COMMON \
		2115	SV *self; /* contains this struct */ \
		2116	SV *cb_sv, *fh /* note no trailing ";" */
		2117
		2118	=item EV_CB_DECLARE (type)
		2119
		2120	=item EV_CB_INVOKE (watcher, revents)
		2121
		2122	=item ev_set_cb (ev, cb)
		2123
		2124	Can be used to change the callback member declaration in each watcher,
		2125	and the way callbacks are invoked and set. Must expand to a struct member
		2126	definition and a statement, respectively. See the F<ev.v> header file for
		2127	their default definitions. One possible use for overriding these is to
		2128	avoid the C<struct ev_loop *> as first argument in all cases, or to use
		2129	method calls instead of plain function calls in C++.
		2130
		2131	=head2 EXAMPLES
		2132
		2133	For a real-world example of a program the includes libev
		2134	verbatim, you can have a look at the EV perl module
		2135	(L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
		2136	the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public
		2137	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
		2138	will be compiled. It is pretty complex because it provides its own header
		2139	file.
		2140
		2141	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
		2142	that everybody includes and which overrides some autoconf choices:
		2143
		2144	#define EV_USE_POLL 0
		2145	#define EV_MULTIPLICITY 0
		2146	#define EV_PERIODICS 0
		2147	#define EV_CONFIG_H <config.h>
		2148
		2149	#include "ev++.h"
		2150
		2151	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
		2152
		2153	#include "ev_cpp.h"
		2154	#include "ev.c"
		2155
		2156
		2157	=head1 COMPLEXITIES
		2158
		2159	In this section the complexities of (many of) the algorithms used inside
		2160	libev will be explained. For complexity discussions about backends see the
		2161	documentation for C<ev_default_init>.
		2162
		2163	=over 4
		2164
		2165	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
		2166
		2167	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
		2168
		2169	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
		2170
		2171	=item Stopping check/prepare/idle watchers: O(1)
		2172
		2173	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2174
		2175	=item Finding the next timer per loop iteration: O(1)
		2176
		2177	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		2178
		2179	=item Activating one watcher: O(1)
		2180
		2181	=back
		2182
1217		2183
1218	=head1 AUTHOR	2184	=head1 AUTHOR
1219		2185
1220	Marc Lehmann <libev@schmorp.de>.	2186	Marc Lehmann <libev@schmorp.de>.
1221		2187

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines