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

Comparing libev/ev.pod (file contents):
Revision 1.48 by root, Tue Nov 27 08:11:52 2007 UTC vs.
Revision 1.88 by ayin, Tue Dec 18 13:06:18 2007 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
		9	=head1 EXAMPLE PROGRAM
		10
		11	#include <ev.h>
		12
		13	ev_io stdin_watcher;
		14	ev_timer timeout_watcher;
		15
		16	/* called when data readable on stdin */
		17	static void
		18	stdin_cb (EV_P_ struct ev_io *w, int revents)
		19	{
		20	/* puts ("stdin ready"); */
		21	ev_io_stop (EV_A_ w); /* just a syntax example */
		22	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		23	}
		24
		25	static void
		26	timeout_cb (EV_P_ struct ev_timer *w, int revents)
		27	{
		28	/* puts ("timeout"); */
		29	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		30	}
		31
		32	int
		33	main (void)
		34	{
		35	struct ev_loop *loop = ev_default_loop (0);
		36
		37	/* initialise an io watcher, then start it */
		38	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
		39	ev_io_start (loop, &stdin_watcher);
		40
		41	/* simple non-repeating 5.5 second timeout */
		42	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		43	ev_timer_start (loop, &timeout_watcher);
		44
		45	/* loop till timeout or data ready */
		46	ev_loop (loop, 0);
		47
		48	return 0;
		49	}
		50
9	=head1 DESCRIPTION	51	=head1 DESCRIPTION
		52
		53	The newest version of this document is also available as a html-formatted
		54	web page you might find easier to navigate when reading it for the first
		55	time: L<http://cvs.schmorp.de/libev/ev.html>.
10		56
11	Libev is an event loop: you register interest in certain events (such as a	57	Libev is an event loop: you register interest in certain events (such as a
12	file descriptor being readable or a timeout occuring), and it will manage	58	file descriptor being readable or a timeout occuring), and it will manage
13	these event sources and provide your program with events.	59	these event sources and provide your program with events.
14		60
…		…
21	details of the event, and then hand it over to libev by I<starting> the	67	details of the event, and then hand it over to libev by I<starting> the
22	watcher.	68	watcher.
23		69
24	=head1 FEATURES	70	=head1 FEATURES
25		71
26	Libev supports select, poll, the linux-specific epoll and the bsd-specific	72	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
27	kqueue mechanisms for file descriptor events, relative timers, absolute	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
28	timers with customised rescheduling, signal events, process status change	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
29	events (related to SIGCHLD), and event watchers dealing with the event	75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
30	loop mechanism itself (idle, prepare and check watchers). It also is quite	76	with customised rescheduling (C<ev_periodic>), synchronous signals
		77	(C<ev_signal>), process status change events (C<ev_child>), and event
		78	watchers dealing with the event loop mechanism itself (C<ev_idle>,
		79	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
		80	file watchers (C<ev_stat>) and even limited support for fork events
		81	(C<ev_fork>).
		82
		83	It also is quite fast (see this
31	fast (see this L<benchmark\|http://libev.schmorp.de/bench.html> comparing	84	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent
32	it to libevent for example).	85	for example).
33		86
34	=head1 CONVENTIONS	87	=head1 CONVENTIONS
35		88
36	Libev is very configurable. In this manual the default configuration	89	Libev is very configurable. In this manual the default configuration will
37	will be described, which supports multiple event loops. For more info	90	be described, which supports multiple event loops. For more info about
38	about various configuration options please have a look at the file	91	various configuration options please have a look at B<EMBED> section in
39	F<README.embed> in the libev distribution. If libev was configured without	92	this manual. If libev was configured without support for multiple event
40	support for multiple event loops, then all functions taking an initial	93	loops, then all functions taking an initial argument of name C<loop>
41	argument of name C<loop> (which is always of type C<struct ev_loop *>)	94	(which is always of type C<struct ev_loop *>) will not have this argument.
42	will not have this argument.
43		95
44	=head1 TIME REPRESENTATION	96	=head1 TIME REPRESENTATION
45		97
46	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	100	the beginning of 1970, details are complicated, don't ask). This type is
49	called C<ev_tstamp>, which is what you should use too. It usually aliases	101	called C<ev_tstamp>, which is what you should use too. It usually aliases
50	to the C<double> type in C, and when you need to do any calculations on	102	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	103	it, you should treat it as some floatingpoint value. Unlike the name
52		104	component C<stamp> might indicate, it is also used for time differences
		105	throughout libev.
53		106
54	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
55		108
56	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
57	library in any way.	110	library in any way.
…		…
66		119
67	=item int ev_version_major ()	120	=item int ev_version_major ()
68		121
69	=item int ev_version_minor ()	122	=item int ev_version_minor ()
70		123
71	You can find out the major and minor version numbers of the library	124	You can find out the major and minor ABI version numbers of the library
72	you linked against by calling the functions C<ev_version_major> and	125	you linked against by calling the functions C<ev_version_major> and
73	C<ev_version_minor>. If you want, you can compare against the global	126	C<ev_version_minor>. If you want, you can compare against the global
74	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	127	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
75	version of the library your program was compiled against.	128	version of the library your program was compiled against.
76		129
		130	These version numbers refer to the ABI version of the library, not the
		131	release version.
		132
77	Usually, it's a good idea to terminate if the major versions mismatch,	133	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	134	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	135	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	136	not a problem.
81		137
82	Example: make sure we haven't accidentally been linked against the wrong	138	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	139	version.
84		140
85	assert (("libev version mismatch",	141	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	142	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	143	&& ev_version_minor () >= EV_VERSION_MINOR));
88		144
…		…
118		174
119	See the description of C<ev_embed> watchers for more info.	175	See the description of C<ev_embed> watchers for more info.
120		176
121	=item ev_set_allocator (void (cb)(void *ptr, long size))	177	=item ev_set_allocator (void (cb)(void *ptr, long size))
122		178
123	Sets the allocation function to use (the prototype is similar to the	179	Sets the allocation function to use (the prototype is similar - the
124	realloc C function, the semantics are identical). It is used to allocate	180	semantics is identical - to the realloc C function). It is used to
125	and free memory (no surprises here). If it returns zero when memory	181	allocate and free memory (no surprises here). If it returns zero when
126	needs to be allocated, the library might abort or take some potentially	182	memory needs to be allocated, the library might abort or take some
127	destructive action. The default is your system realloc function.	183	potentially destructive action. The default is your system realloc
		184	function.
128		185
129	You could override this function in high-availability programs to, say,	186	You could override this function in high-availability programs to, say,
130	free some memory if it cannot allocate memory, to use a special allocator,	187	free some memory if it cannot allocate memory, to use a special allocator,
131	or even to sleep a while and retry until some memory is available.	188	or even to sleep a while and retry until some memory is available.
132		189
133	Example: replace the libev allocator with one that waits a bit and then	190	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	191	retries).
135		192
136	static void *	193	static void *
137	persistent_realloc (void *ptr, long size)	194	persistent_realloc (void *ptr, size_t size)
138	{	195	{
139	for (;;)	196	for (;;)
140	{	197	{
141	void *newptr = realloc (ptr, size);	198	void *newptr = realloc (ptr, size);
142		199
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	215	callback is set, then libev will expect it to remedy the sitution, no
159	matter what, when it returns. That is, libev will generally retry the	216	matter what, when it returns. That is, libev will generally retry the
160	requested operation, or, if the condition doesn't go away, do bad stuff	217	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	218	(such as abort).
162		219
163	Example: do the same thing as libev does internally:	220	Example: This is basically the same thing that libev does internally, too.
164		221
165	static void	222	static void
166	fatal_error (const char *msg)	223	fatal_error (const char *msg)
167	{	224	{
168	perror (msg);	225	perror (msg);
…		…
218	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	275	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
219	override the flags completely if it is found in the environment. This is	276	override the flags completely if it is found in the environment. This is
220	useful to try out specific backends to test their performance, or to work	277	useful to try out specific backends to test their performance, or to work
221	around bugs.	278	around bugs.
222		279
		280	=item C<EVFLAG_FORKCHECK>
		281
		282	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		283	a fork, you can also make libev check for a fork in each iteration by
		284	enabling this flag.
		285
		286	This works by calling C<getpid ()> on every iteration of the loop,
		287	and thus this might slow down your event loop if you do a lot of loop
		288	iterations and little real work, but is usually not noticeable (on my
		289	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		290	without a syscall and thus I<very> fast, but my Linux system also has
		291	C<pthread_atfork> which is even faster).
		292
		293	The big advantage of this flag is that you can forget about fork (and
		294	forget about forgetting to tell libev about forking) when you use this
		295	flag.
		296
		297	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		298	environment variable.
		299
223	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	300	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
224		301
225	This is your standard select(2) backend. Not I<completely> standard, as	302	This is your standard select(2) backend. Not I<completely> standard, as
226	libev tries to roll its own fd_set with no limits on the number of fds,	303	libev tries to roll its own fd_set with no limits on the number of fds,
227	but if that fails, expect a fairly low limit on the number of fds when	304	but if that fails, expect a fairly low limit on the number of fds when
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	391	Similar to C<ev_default_loop>, but always creates a new event loop that is
315	always distinct from the default loop. Unlike the default loop, it cannot	392	always distinct from the default loop. Unlike the default loop, it cannot
316	handle signal and child watchers, and attempts to do so will be greeted by	393	handle signal and child watchers, and attempts to do so will be greeted by
317	undefined behaviour (or a failed assertion if assertions are enabled).	394	undefined behaviour (or a failed assertion if assertions are enabled).
318		395
319	Example: try to create a event loop that uses epoll and nothing else.	396	Example: Try to create a event loop that uses epoll and nothing else.
320		397
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	398	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
322	if (!epoller)	399	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	400	fatal ("no epoll found here, maybe it hides under your chair");
324		401
…		…
327	Destroys the default loop again (frees all memory and kernel state	404	Destroys the default loop again (frees all memory and kernel state
328	etc.). None of the active event watchers will be stopped in the normal	405	etc.). None of the active event watchers will be stopped in the normal
329	sense, so e.g. C<ev_is_active> might still return true. It is your	406	sense, so e.g. C<ev_is_active> might still return true. It is your
330	responsibility to either stop all watchers cleanly yoursef I<before>	407	responsibility to either stop all watchers cleanly yoursef I<before>
331	calling this function, or cope with the fact afterwards (which is usually	408	calling this function, or cope with the fact afterwards (which is usually
332	the easiest thing, youc na just ignore the watchers and/or C<free ()> them	409	the easiest thing, you can just ignore the watchers and/or C<free ()> them
333	for example).	410	for example).
		411
		412	Note that certain global state, such as signal state, will not be freed by
		413	this function, and related watchers (such as signal and child watchers)
		414	would need to be stopped manually.
		415
		416	In general it is not advisable to call this function except in the
		417	rare occasion where you really need to free e.g. the signal handling
		418	pipe fds. If you need dynamically allocated loops it is better to use
		419	C<ev_loop_new> and C<ev_loop_destroy>).
334		420
335	=item ev_loop_destroy (loop)	421	=item ev_loop_destroy (loop)
336		422
337	Like C<ev_default_destroy>, but destroys an event loop created by an	423	Like C<ev_default_destroy>, but destroys an event loop created by an
338	earlier call to C<ev_loop_new>.	424	earlier call to C<ev_loop_new>.
…		…
361	=item ev_loop_fork (loop)	447	=item ev_loop_fork (loop)
362		448
363	Like C<ev_default_fork>, but acts on an event loop created by	449	Like C<ev_default_fork>, but acts on an event loop created by
364	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	450	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
365	after fork, and how you do this is entirely your own problem.	451	after fork, and how you do this is entirely your own problem.
		452
		453	=item unsigned int ev_loop_count (loop)
		454
		455	Returns the count of loop iterations for the loop, which is identical to
		456	the number of times libev did poll for new events. It starts at C<0> and
		457	happily wraps around with enough iterations.
		458
		459	This value can sometimes be useful as a generation counter of sorts (it
		460	"ticks" the number of loop iterations), as it roughly corresponds with
		461	C<ev_prepare> and C<ev_check> calls.
366		462
367	=item unsigned int ev_backend (loop)	463	=item unsigned int ev_backend (loop)
368		464
369	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	465	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
370	use.	466	use.
…		…
404	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	500	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
405	usually a better approach for this kind of thing.	501	usually a better approach for this kind of thing.
406		502
407	Here are the gory details of what C<ev_loop> does:	503	Here are the gory details of what C<ev_loop> does:
408		504
		505	- Before the first iteration, call any pending watchers.
409	* If there are no active watchers (reference count is zero), return.	506	* If there are no active watchers (reference count is zero), return.
410	- Queue prepare watchers and then call all outstanding watchers.	507	- Queue all prepare watchers and then call all outstanding watchers.
411	- If we have been forked, recreate the kernel state.	508	- If we have been forked, recreate the kernel state.
412	- Update the kernel state with all outstanding changes.	509	- Update the kernel state with all outstanding changes.
413	- Update the "event loop time".	510	- Update the "event loop time".
414	- Calculate for how long to block.	511	- Calculate for how long to block.
415	- Block the process, waiting for any events.	512	- Block the process, waiting for any events.
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	520	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	521	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	522	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	523	were used, return, otherwise continue with step *.
427		524
428	Example: queue some jobs and then loop until no events are outsanding	525	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	526	anymore.
430		527
431	... queue jobs here, make sure they register event watchers as long	528	... queue jobs here, make sure they register event watchers as long
432	... as they still have work to do (even an idle watcher will do..)	529	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	530	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	550	visible to the libev user and should not keep C<ev_loop> from exiting if
454	no event watchers registered by it are active. It is also an excellent	551	no event watchers registered by it are active. It is also an excellent
455	way to do this for generic recurring timers or from within third-party	552	way to do this for generic recurring timers or from within third-party
456	libraries. Just remember to I<unref after start> and I<ref before stop>.	553	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		554
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	555	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	556	running when nothing else is active.
460		557
461	struct dv_signal exitsig;	558	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	559	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	560	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	561	evf_unref (loop);
465		562
466	Example: for some weird reason, unregister the above signal handler again.	563	Example: For some weird reason, unregister the above signal handler again.
467		564
468	ev_ref (myloop);	565	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	566	ev_signal_stop (loop, &exitsig);
470		567
471	=back	568	=back
472		569
473		570
474	=head1 ANATOMY OF A WATCHER	571	=head1 ANATOMY OF A WATCHER
…		…
565	received events. Callbacks of both watcher types can start and stop as	662	received events. Callbacks of both watcher types can start and stop as
566	many watchers as they want, and all of them will be taken into account	663	many watchers as they want, and all of them will be taken into account
567	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	664	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
568	C<ev_loop> from blocking).	665	C<ev_loop> from blocking).
569		666
		667	=item C<EV_EMBED>
		668
		669	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		670
		671	=item C<EV_FORK>
		672
		673	The event loop has been resumed in the child process after fork (see
		674	C<ev_fork>).
		675
570	=item C<EV_ERROR>	676	=item C<EV_ERROR>
571		677
572	An unspecified error has occured, the watcher has been stopped. This might	678	An unspecified error has occured, the watcher has been stopped. This might
573	happen because the watcher could not be properly started because libev	679	happen because the watcher could not be properly started because libev
574	ran out of memory, a file descriptor was found to be closed or any other	680	ran out of memory, a file descriptor was found to be closed or any other
…		…
645	=item bool ev_is_pending (ev_TYPE *watcher)	751	=item bool ev_is_pending (ev_TYPE *watcher)
646		752
647	Returns a true value iff the watcher is pending, (i.e. it has outstanding	753	Returns a true value iff the watcher is pending, (i.e. it has outstanding
648	events but its callback has not yet been invoked). As long as a watcher	754	events but its callback has not yet been invoked). As long as a watcher
649	is pending (but not active) you must not call an init function on it (but	755	is pending (but not active) you must not call an init function on it (but
650	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	756	C<ev_TYPE_set> is safe), you must not change its priority, and you must
651	libev (e.g. you cnanot C<free ()> it).	757	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		758	it).
652		759
653	=item callback = ev_cb (ev_TYPE *watcher)	760	=item callback ev_cb (ev_TYPE *watcher)
654		761
655	Returns the callback currently set on the watcher.	762	Returns the callback currently set on the watcher.
656		763
657	=item ev_cb_set (ev_TYPE *watcher, callback)	764	=item ev_cb_set (ev_TYPE *watcher, callback)
658		765
659	Change the callback. You can change the callback at virtually any time	766	Change the callback. You can change the callback at virtually any time
660	(modulo threads).	767	(modulo threads).
		768
		769	=item ev_set_priority (ev_TYPE *watcher, priority)
		770
		771	=item int ev_priority (ev_TYPE *watcher)
		772
		773	Set and query the priority of the watcher. The priority is a small
		774	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		775	(default: C<-2>). Pending watchers with higher priority will be invoked
		776	before watchers with lower priority, but priority will not keep watchers
		777	from being executed (except for C<ev_idle> watchers).
		778
		779	This means that priorities are I<only> used for ordering callback
		780	invocation after new events have been received. This is useful, for
		781	example, to reduce latency after idling, or more often, to bind two
		782	watchers on the same event and make sure one is called first.
		783
		784	If you need to suppress invocation when higher priority events are pending
		785	you need to look at C<ev_idle> watchers, which provide this functionality.
		786
		787	You I<must not> change the priority of a watcher as long as it is active or
		788	pending.
		789
		790	The default priority used by watchers when no priority has been set is
		791	always C<0>, which is supposed to not be too high and not be too low :).
		792
		793	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		794	fine, as long as you do not mind that the priority value you query might
		795	or might not have been adjusted to be within valid range.
		796
		797	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		798
		799	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		800	C<loop> nor C<revents> need to be valid as long as the watcher callback
		801	can deal with that fact.
		802
		803	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		804
		805	If the watcher is pending, this function returns clears its pending status
		806	and returns its C<revents> bitset (as if its callback was invoked). If the
		807	watcher isn't pending it does nothing and returns C<0>.
661		808
662	=back	809	=back
663		810
664		811
665	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	812	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
686	{	833	{
687	struct my_io w = (struct my_io )w_;	834	struct my_io w = (struct my_io )w_;
688	...	835	...
689	}	836	}
690		837
691	More interesting and less C-conformant ways of catsing your callback type	838	More interesting and less C-conformant ways of casting your callback type
692	have been omitted....	839	instead have been omitted.
		840
		841	Another common scenario is having some data structure with multiple
		842	watchers:
		843
		844	struct my_biggy
		845	{
		846	int some_data;
		847	ev_timer t1;
		848	ev_timer t2;
		849	}
		850
		851	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		852	you need to use C<offsetof>:
		853
		854	#include <stddef.h>
		855
		856	static void
		857	t1_cb (EV_P_ struct ev_timer *w, int revents)
		858	{
		859	struct my_biggy big = (struct my_biggy *
		860	(((char *)w) - offsetof (struct my_biggy, t1));
		861	}
		862
		863	static void
		864	t2_cb (EV_P_ struct ev_timer *w, int revents)
		865	{
		866	struct my_biggy big = (struct my_biggy *
		867	(((char *)w) - offsetof (struct my_biggy, t2));
		868	}
693		869
694		870
695	=head1 WATCHER TYPES	871	=head1 WATCHER TYPES
696		872
697	This section describes each watcher in detail, but will not repeat	873	This section describes each watcher in detail, but will not repeat
…		…
742	it is best to always use non-blocking I/O: An extra C<read>(2) returning	918	it is best to always use non-blocking I/O: An extra C<read>(2) returning
743	C<EAGAIN> is far preferable to a program hanging until some data arrives.	919	C<EAGAIN> is far preferable to a program hanging until some data arrives.
744		920
745	If you cannot run the fd in non-blocking mode (for example you should not	921	If you cannot run the fd in non-blocking mode (for example you should not
746	play around with an Xlib connection), then you have to seperately re-test	922	play around with an Xlib connection), then you have to seperately re-test
747	wether a file descriptor is really ready with a known-to-be good interface	923	whether a file descriptor is really ready with a known-to-be good interface
748	such as poll (fortunately in our Xlib example, Xlib already does this on	924	such as poll (fortunately in our Xlib example, Xlib already does this on
749	its own, so its quite safe to use).	925	its own, so its quite safe to use).
		926
		927	=head3 The special problem of disappearing file descriptors
		928
		929	Some backends (e.g kqueue, epoll) need to be told about closing a file
		930	descriptor (either by calling C<close> explicitly or by any other means,
		931	such as C<dup>). The reason is that you register interest in some file
		932	descriptor, but when it goes away, the operating system will silently drop
		933	this interest. If another file descriptor with the same number then is
		934	registered with libev, there is no efficient way to see that this is, in
		935	fact, a different file descriptor.
		936
		937	To avoid having to explicitly tell libev about such cases, libev follows
		938	the following policy: Each time C<ev_io_set> is being called, libev
		939	will assume that this is potentially a new file descriptor, otherwise
		940	it is assumed that the file descriptor stays the same. That means that
		941	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		942	descriptor even if the file descriptor number itself did not change.
		943
		944	This is how one would do it normally anyway, the important point is that
		945	the libev application should not optimise around libev but should leave
		946	optimisations to libev.
		947
		948
		949	=head3 Watcher-Specific Functions
750		950
751	=over 4	951	=over 4
752		952
753	=item ev_io_init (ev_io *, callback, int fd, int events)	953	=item ev_io_init (ev_io *, callback, int fd, int events)
754		954
…		…
766		966
767	The events being watched.	967	The events being watched.
768		968
769	=back	969	=back
770		970
771	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	971	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
772	readable, but only once. Since it is likely line-buffered, you could	972	readable, but only once. Since it is likely line-buffered, you could
773	attempt to read a whole line in the callback:	973	attempt to read a whole line in the callback.
774		974
775	static void	975	static void
776	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	976	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
777	{	977	{
778	ev_io_stop (loop, w);	978	ev_io_stop (loop, w);
…		…
808		1008
809	The callback is guarenteed to be invoked only when its timeout has passed,	1009	The callback is guarenteed to be invoked only when its timeout has passed,
810	but if multiple timers become ready during the same loop iteration then	1010	but if multiple timers become ready during the same loop iteration then
811	order of execution is undefined.	1011	order of execution is undefined.
812		1012
		1013	=head3 Watcher-Specific Functions and Data Members
		1014
813	=over 4	1015	=over 4
814		1016
815	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1017	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
816		1018
817	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1019	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
830	=item ev_timer_again (loop)	1032	=item ev_timer_again (loop)
831		1033
832	This will act as if the timer timed out and restart it again if it is	1034	This will act as if the timer timed out and restart it again if it is
833	repeating. The exact semantics are:	1035	repeating. The exact semantics are:
834		1036
		1037	If the timer is pending, its pending status is cleared.
		1038
835	If the timer is started but nonrepeating, stop it.	1039	If the timer is started but nonrepeating, stop it (as if it timed out).
836		1040
837	If the timer is repeating, either start it if necessary (with the repeat	1041	If the timer is repeating, either start it if necessary (with the
838	value), or reset the running timer to the repeat value.	1042	C<repeat> value), or reset the running timer to the C<repeat> value.
839		1043
840	This sounds a bit complicated, but here is a useful and typical	1044	This sounds a bit complicated, but here is a useful and typical
841	example: Imagine you have a tcp connection and you want a so-called	1045	example: Imagine you have a tcp connection and you want a so-called idle
842	idle timeout, that is, you want to be called when there have been,	1046	timeout, that is, you want to be called when there have been, say, 60
843	say, 60 seconds of inactivity on the socket. The easiest way to do	1047	seconds of inactivity on the socket. The easiest way to do this is to
844	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	1048	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
845	C<ev_timer_again> each time you successfully read or write some data. If	1049	C<ev_timer_again> each time you successfully read or write some data. If
846	you go into an idle state where you do not expect data to travel on the	1050	you go into an idle state where you do not expect data to travel on the
847	socket, you can stop the timer, and again will automatically restart it if	1051	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
848	need be.	1052	automatically restart it if need be.
849		1053
850	You can also ignore the C<after> value and C<ev_timer_start> altogether	1054	That means you can ignore the C<after> value and C<ev_timer_start>
851	and only ever use the C<repeat> value:	1055	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
852		1056
853	ev_timer_init (timer, callback, 0., 5.);	1057	ev_timer_init (timer, callback, 0., 5.);
854	ev_timer_again (loop, timer);	1058	ev_timer_again (loop, timer);
855	...	1059	...
856	timer->again = 17.;	1060	timer->again = 17.;
857	ev_timer_again (loop, timer);	1061	ev_timer_again (loop, timer);
858	...	1062	...
859	timer->again = 10.;	1063	timer->again = 10.;
860	ev_timer_again (loop, timer);	1064	ev_timer_again (loop, timer);
861		1065
862	This is more efficient then stopping/starting the timer eahc time you want	1066	This is more slightly efficient then stopping/starting the timer each time
863	to modify its timeout value.	1067	you want to modify its timeout value.
864		1068
865	=item ev_tstamp repeat [read-write]	1069	=item ev_tstamp repeat [read-write]
866		1070
867	The current C<repeat> value. Will be used each time the watcher times out	1071	The current C<repeat> value. Will be used each time the watcher times out
868	or C<ev_timer_again> is called and determines the next timeout (if any),	1072	or C<ev_timer_again> is called and determines the next timeout (if any),
869	which is also when any modifications are taken into account.	1073	which is also when any modifications are taken into account.
870		1074
871	=back	1075	=back
872		1076
873	Example: create a timer that fires after 60 seconds.	1077	Example: Create a timer that fires after 60 seconds.
874		1078
875	static void	1079	static void
876	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1080	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
877	{	1081	{
878	.. one minute over, w is actually stopped right here	1082	.. one minute over, w is actually stopped right here
…		…
880		1084
881	struct ev_timer mytimer;	1085	struct ev_timer mytimer;
882	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1086	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
883	ev_timer_start (loop, &mytimer);	1087	ev_timer_start (loop, &mytimer);
884		1088
885	Example: create a timeout timer that times out after 10 seconds of	1089	Example: Create a timeout timer that times out after 10 seconds of
886	inactivity.	1090	inactivity.
887		1091
888	static void	1092	static void
889	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1093	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
890	{	1094	{
…		…
910	but on wallclock time (absolute time). You can tell a periodic watcher	1114	but on wallclock time (absolute time). You can tell a periodic watcher
911	to trigger "at" some specific point in time. For example, if you tell a	1115	to trigger "at" some specific point in time. For example, if you tell a
912	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1116	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
913	+ 10.>) and then reset your system clock to the last year, then it will	1117	+ 10.>) and then reset your system clock to the last year, then it will
914	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1118	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
915	roughly 10 seconds later and of course not if you reset your system time	1119	roughly 10 seconds later).
916	again).
917		1120
918	They can also be used to implement vastly more complex timers, such as	1121	They can also be used to implement vastly more complex timers, such as
919	triggering an event on eahc midnight, local time.	1122	triggering an event on each midnight, local time or other, complicated,
		1123	rules.
920		1124
921	As with timers, the callback is guarenteed to be invoked only when the	1125	As with timers, the callback is guarenteed to be invoked only when the
922	time (C<at>) has been passed, but if multiple periodic timers become ready	1126	time (C<at>) has been passed, but if multiple periodic timers become ready
923	during the same loop iteration then order of execution is undefined.	1127	during the same loop iteration then order of execution is undefined.
924		1128
		1129	=head3 Watcher-Specific Functions and Data Members
		1130
925	=over 4	1131	=over 4
926		1132
927	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1133	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
928		1134
929	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1135	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
931	Lots of arguments, lets sort it out... There are basically three modes of	1137	Lots of arguments, lets sort it out... There are basically three modes of
932	operation, and we will explain them from simplest to complex:	1138	operation, and we will explain them from simplest to complex:
933		1139
934	=over 4	1140	=over 4
935		1141
936	=item * absolute timer (interval = reschedule_cb = 0)	1142	=item * absolute timer (at = time, interval = reschedule_cb = 0)
937		1143
938	In this configuration the watcher triggers an event at the wallclock time	1144	In this configuration the watcher triggers an event at the wallclock time
939	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1145	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
940	that is, if it is to be run at January 1st 2011 then it will run when the	1146	that is, if it is to be run at January 1st 2011 then it will run when the
941	system time reaches or surpasses this time.	1147	system time reaches or surpasses this time.
942		1148
943	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1149	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
944		1150
945	In this mode the watcher will always be scheduled to time out at the next	1151	In this mode the watcher will always be scheduled to time out at the next
946	C<at + N * interval> time (for some integer N) and then repeat, regardless	1152	C<at + N * interval> time (for some integer N, which can also be negative)
947	of any time jumps.	1153	and then repeat, regardless of any time jumps.
948		1154
949	This can be used to create timers that do not drift with respect to system	1155	This can be used to create timers that do not drift with respect to system
950	time:	1156	time:
951		1157
952	ev_periodic_set (&periodic, 0., 3600., 0);	1158	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
958		1164
959	Another way to think about it (for the mathematically inclined) is that	1165	Another way to think about it (for the mathematically inclined) is that
960	C<ev_periodic> will try to run the callback in this mode at the next possible	1166	C<ev_periodic> will try to run the callback in this mode at the next possible
961	time where C<time = at (mod interval)>, regardless of any time jumps.	1167	time where C<time = at (mod interval)>, regardless of any time jumps.
962		1168
		1169	For numerical stability it is preferable that the C<at> value is near
		1170	C<ev_now ()> (the current time), but there is no range requirement for
		1171	this value.
		1172
963	=item * manual reschedule mode (reschedule_cb = callback)	1173	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
964		1174
965	In this mode the values for C<interval> and C<at> are both being	1175	In this mode the values for C<interval> and C<at> are both being
966	ignored. Instead, each time the periodic watcher gets scheduled, the	1176	ignored. Instead, each time the periodic watcher gets scheduled, the
967	reschedule callback will be called with the watcher as first, and the	1177	reschedule callback will be called with the watcher as first, and the
968	current time as second argument.	1178	current time as second argument.
969		1179
970	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1180	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
971	ever, or make any event loop modifications>. If you need to stop it,	1181	ever, or make any event loop modifications>. If you need to stop it,
972	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1182	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
973	starting a prepare watcher).	1183	starting an C<ev_prepare> watcher, which is legal).
974		1184
975	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1185	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
976	ev_tstamp now)>, e.g.:	1186	ev_tstamp now)>, e.g.:
977		1187
978	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1188	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1001	Simply stops and restarts the periodic watcher again. This is only useful	1211	Simply stops and restarts the periodic watcher again. This is only useful
1002	when you changed some parameters or the reschedule callback would return	1212	when you changed some parameters or the reschedule callback would return
1003	a different time than the last time it was called (e.g. in a crond like	1213	a different time than the last time it was called (e.g. in a crond like
1004	program when the crontabs have changed).	1214	program when the crontabs have changed).
1005		1215
		1216	=item ev_tstamp offset [read-write]
		1217
		1218	When repeating, this contains the offset value, otherwise this is the
		1219	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1220
		1221	Can be modified any time, but changes only take effect when the periodic
		1222	timer fires or C<ev_periodic_again> is being called.
		1223
1006	=item ev_tstamp interval [read-write]	1224	=item ev_tstamp interval [read-write]
1007		1225
1008	The current interval value. Can be modified any time, but changes only	1226	The current interval value. Can be modified any time, but changes only
1009	take effect when the periodic timer fires or C<ev_periodic_again> is being	1227	take effect when the periodic timer fires or C<ev_periodic_again> is being
1010	called.	1228	called.
…		…
1013		1231
1014	The current reschedule callback, or C<0>, if this functionality is	1232	The current reschedule callback, or C<0>, if this functionality is
1015	switched off. Can be changed any time, but changes only take effect when	1233	switched off. Can be changed any time, but changes only take effect when
1016	the periodic timer fires or C<ev_periodic_again> is being called.	1234	the periodic timer fires or C<ev_periodic_again> is being called.
1017		1235
		1236	=item ev_tstamp at [read-only]
		1237
		1238	When active, contains the absolute time that the watcher is supposed to
		1239	trigger next.
		1240
1018	=back	1241	=back
1019		1242
1020	Example: call a callback every hour, or, more precisely, whenever the	1243	Example: Call a callback every hour, or, more precisely, whenever the
1021	system clock is divisible by 3600. The callback invocation times have	1244	system clock is divisible by 3600. The callback invocation times have
1022	potentially a lot of jittering, but good long-term stability.	1245	potentially a lot of jittering, but good long-term stability.
1023		1246
1024	static void	1247	static void
1025	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1248	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
1029		1252
1030	struct ev_periodic hourly_tick;	1253	struct ev_periodic hourly_tick;
1031	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1254	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1032	ev_periodic_start (loop, &hourly_tick);	1255	ev_periodic_start (loop, &hourly_tick);
1033		1256
1034	Example: the same as above, but use a reschedule callback to do it:	1257	Example: The same as above, but use a reschedule callback to do it:
1035		1258
1036	#include <math.h>	1259	#include <math.h>
1037		1260
1038	static ev_tstamp	1261	static ev_tstamp
1039	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1262	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
1041	return fmod (now, 3600.) + 3600.;	1264	return fmod (now, 3600.) + 3600.;
1042	}	1265	}
1043		1266
1044	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1267	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1045		1268
1046	Example: call a callback every hour, starting now:	1269	Example: Call a callback every hour, starting now:
1047		1270
1048	struct ev_periodic hourly_tick;	1271	struct ev_periodic hourly_tick;
1049	ev_periodic_init (&hourly_tick, clock_cb,	1272	ev_periodic_init (&hourly_tick, clock_cb,
1050	fmod (ev_now (loop), 3600.), 3600., 0);	1273	fmod (ev_now (loop), 3600.), 3600., 0);
1051	ev_periodic_start (loop, &hourly_tick);	1274	ev_periodic_start (loop, &hourly_tick);
…		…
1063	with the kernel (thus it coexists with your own signal handlers as long	1286	with the kernel (thus it coexists with your own signal handlers as long
1064	as you don't register any with libev). Similarly, when the last signal	1287	as you don't register any with libev). Similarly, when the last signal
1065	watcher for a signal is stopped libev will reset the signal handler to	1288	watcher for a signal is stopped libev will reset the signal handler to
1066	SIG_DFL (regardless of what it was set to before).	1289	SIG_DFL (regardless of what it was set to before).
1067		1290
		1291	=head3 Watcher-Specific Functions and Data Members
		1292
1068	=over 4	1293	=over 4
1069		1294
1070	=item ev_signal_init (ev_signal *, callback, int signum)	1295	=item ev_signal_init (ev_signal *, callback, int signum)
1071		1296
1072	=item ev_signal_set (ev_signal *, int signum)	1297	=item ev_signal_set (ev_signal *, int signum)
…		…
1083		1308
1084	=head2 C<ev_child> - watch out for process status changes	1309	=head2 C<ev_child> - watch out for process status changes
1085		1310
1086	Child watchers trigger when your process receives a SIGCHLD in response to	1311	Child watchers trigger when your process receives a SIGCHLD in response to
1087	some child status changes (most typically when a child of yours dies).	1312	some child status changes (most typically when a child of yours dies).
		1313
		1314	=head3 Watcher-Specific Functions and Data Members
1088		1315
1089	=over 4	1316	=over 4
1090		1317
1091	=item ev_child_init (ev_child *, callback, int pid)	1318	=item ev_child_init (ev_child *, callback, int pid)
1092		1319
…		…
1112	The process exit/trace status caused by C<rpid> (see your systems	1339	The process exit/trace status caused by C<rpid> (see your systems
1113	C<waitpid> and C<sys/wait.h> documentation for details).	1340	C<waitpid> and C<sys/wait.h> documentation for details).
1114		1341
1115	=back	1342	=back
1116		1343
1117	Example: try to exit cleanly on SIGINT and SIGTERM.	1344	Example: Try to exit cleanly on SIGINT and SIGTERM.
1118		1345
1119	static void	1346	static void
1120	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1347	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1121	{	1348	{
1122	ev_unloop (loop, EVUNLOOP_ALL);	1349	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1137	not exist" is a status change like any other. The condition "path does	1364	not exist" is a status change like any other. The condition "path does
1138	not exist" is signified by the C<st_nlink> field being zero (which is	1365	not exist" is signified by the C<st_nlink> field being zero (which is
1139	otherwise always forced to be at least one) and all the other fields of	1366	otherwise always forced to be at least one) and all the other fields of
1140	the stat buffer having unspecified contents.	1367	the stat buffer having unspecified contents.
1141		1368
		1369	The path I<should> be absolute and I<must not> end in a slash. If it is
		1370	relative and your working directory changes, the behaviour is undefined.
		1371
1142	Since there is no standard to do this, the portable implementation simply	1372	Since there is no standard to do this, the portable implementation simply
1143	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1373	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1144	can specify a recommended polling interval for this case. If you specify	1374	can specify a recommended polling interval for this case. If you specify
1145	a polling interval of C<0> (highly recommended!) then a I<suitable,	1375	a polling interval of C<0> (highly recommended!) then a I<suitable,
1146	unspecified default> value will be used (which you can expect to be around	1376	unspecified default> value will be used (which you can expect to be around
1147	five seconds, although this might change dynamically). Libev will also	1377	five seconds, although this might change dynamically). Libev will also
1148	impose a minimum interval which is currently around C<0.1>, but thats	1378	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1150		1380
1151	This watcher type is not meant for massive numbers of stat watchers,	1381	This watcher type is not meant for massive numbers of stat watchers,
1152	as even with OS-supported change notifications, this can be	1382	as even with OS-supported change notifications, this can be
1153	resource-intensive.	1383	resource-intensive.
1154		1384
1155	At the time of this writing, no specific OS backends are implemented, but	1385	At the time of this writing, only the Linux inotify interface is
1156	if demand increases, at least a kqueue and inotify backend will be added.	1386	implemented (implementing kqueue support is left as an exercise for the
		1387	reader). Inotify will be used to give hints only and should not change the
		1388	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1389	to fall back to regular polling again even with inotify, but changes are
		1390	usually detected immediately, and if the file exists there will be no
		1391	polling.
		1392
		1393	=head3 Watcher-Specific Functions and Data Members
1157		1394
1158	=over 4	1395	=over 4
1159		1396
1160	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1397	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1161		1398
…		…
1225	ev_stat_start (loop, &passwd);	1462	ev_stat_start (loop, &passwd);
1226		1463
1227		1464
1228	=head2 C<ev_idle> - when you've got nothing better to do...	1465	=head2 C<ev_idle> - when you've got nothing better to do...
1229		1466
1230	Idle watchers trigger events when there are no other events are pending	1467	Idle watchers trigger events when no other events of the same or higher
1231	(prepare, check and other idle watchers do not count). That is, as long	1468	priority are pending (prepare, check and other idle watchers do not
1232	as your process is busy handling sockets or timeouts (or even signals,	1469	count).
1233	imagine) it will not be triggered. But when your process is idle all idle	1470
1234	watchers are being called again and again, once per event loop iteration -	1471	That is, as long as your process is busy handling sockets or timeouts
		1472	(or even signals, imagine) of the same or higher priority it will not be
		1473	triggered. But when your process is idle (or only lower-priority watchers
		1474	are pending), the idle watchers are being called once per event loop
1235	until stopped, that is, or your process receives more events and becomes	1475	iteration - until stopped, that is, or your process receives more events
1236	busy.	1476	and becomes busy again with higher priority stuff.
1237		1477
1238	The most noteworthy effect is that as long as any idle watchers are	1478	The most noteworthy effect is that as long as any idle watchers are
1239	active, the process will not block when waiting for new events.	1479	active, the process will not block when waiting for new events.
1240		1480
1241	Apart from keeping your process non-blocking (which is a useful	1481	Apart from keeping your process non-blocking (which is a useful
1242	effect on its own sometimes), idle watchers are a good place to do	1482	effect on its own sometimes), idle watchers are a good place to do
1243	"pseudo-background processing", or delay processing stuff to after the	1483	"pseudo-background processing", or delay processing stuff to after the
1244	event loop has handled all outstanding events.	1484	event loop has handled all outstanding events.
1245		1485
		1486	=head3 Watcher-Specific Functions and Data Members
		1487
1246	=over 4	1488	=over 4
1247		1489
1248	=item ev_idle_init (ev_signal *, callback)	1490	=item ev_idle_init (ev_signal *, callback)
1249		1491
1250	Initialises and configures the idle watcher - it has no parameters of any	1492	Initialises and configures the idle watcher - it has no parameters of any
1251	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1493	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1252	believe me.	1494	believe me.
1253		1495
1254	=back	1496	=back
1255		1497
1256	Example: dynamically allocate an C<ev_idle>, start it, and in the	1498	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1257	callback, free it. Alos, use no error checking, as usual.	1499	callback, free it. Also, use no error checking, as usual.
1258		1500
1259	static void	1501	static void
1260	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1502	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1261	{	1503	{
1262	free (w);	1504	free (w);
…		…
1307	with priority higher than or equal to the event loop and one coroutine	1549	with priority higher than or equal to the event loop and one coroutine
1308	of lower priority, but only once, using idle watchers to keep the event	1550	of lower priority, but only once, using idle watchers to keep the event
1309	loop from blocking if lower-priority coroutines are active, thus mapping	1551	loop from blocking if lower-priority coroutines are active, thus mapping
1310	low-priority coroutines to idle/background tasks).	1552	low-priority coroutines to idle/background tasks).
1311		1553
		1554	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1555	priority, to ensure that they are being run before any other watchers
		1556	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1557	too) should not activate ("feed") events into libev. While libev fully
		1558	supports this, they will be called before other C<ev_check> watchers did
		1559	their job. As C<ev_check> watchers are often used to embed other event
		1560	loops those other event loops might be in an unusable state until their
		1561	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1562	others).
		1563
		1564	=head3 Watcher-Specific Functions and Data Members
		1565
1312	=over 4	1566	=over 4
1313		1567
1314	=item ev_prepare_init (ev_prepare *, callback)	1568	=item ev_prepare_init (ev_prepare *, callback)
1315		1569
1316	=item ev_check_init (ev_check *, callback)	1570	=item ev_check_init (ev_check *, callback)
…		…
1319	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1573	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1320	macros, but using them is utterly, utterly and completely pointless.	1574	macros, but using them is utterly, utterly and completely pointless.
1321		1575
1322	=back	1576	=back
1323		1577
1324	Example: To include a library such as adns, you would add IO watchers	1578	There are a number of principal ways to embed other event loops or modules
1325	and a timeout watcher in a prepare handler, as required by libadns, and	1579	into libev. Here are some ideas on how to include libadns into libev
		1580	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1581	use for an actually working example. Another Perl module named C<EV::Glib>
		1582	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1583	into the Glib event loop).
		1584
		1585	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1326	in a check watcher, destroy them and call into libadns. What follows is	1586	and in a check watcher, destroy them and call into libadns. What follows
1327	pseudo-code only of course:	1587	is pseudo-code only of course. This requires you to either use a low
		1588	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1589	the callbacks for the IO/timeout watchers might not have been called yet.
1328		1590
1329	static ev_io iow [nfd];	1591	static ev_io iow [nfd];
1330	static ev_timer tw;	1592	static ev_timer tw;
1331		1593
1332	static void	1594	static void
1333	io_cb (ev_loop loop, ev_io w, int revents)	1595	io_cb (ev_loop loop, ev_io w, int revents)
1334	{	1596	{
1335	// set the relevant poll flags
1336	// could also call adns_processreadable etc. here
1337	struct pollfd fd = (struct pollfd )w->data;
1338	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1339	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1340	}	1597	}
1341		1598
1342	// create io watchers for each fd and a timer before blocking	1599	// create io watchers for each fd and a timer before blocking
1343	static void	1600	static void
1344	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1601	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1345	{	1602	{
1346	int timeout = 3600000;truct pollfd fds [nfd];	1603	int timeout = 3600000;
		1604	struct pollfd fds [nfd];
1347	// actual code will need to loop here and realloc etc.	1605	// actual code will need to loop here and realloc etc.
1348	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1606	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1349		1607
1350	/* the callback is illegal, but won't be called as we stop during check */	1608	/* the callback is illegal, but won't be called as we stop during check */
1351	ev_timer_init (&tw, 0, timeout * 1e-3);	1609	ev_timer_init (&tw, 0, timeout * 1e-3);
1352	ev_timer_start (loop, &tw);	1610	ev_timer_start (loop, &tw);
1353		1611
1354	// create on ev_io per pollfd	1612	// create one ev_io per pollfd
1355	for (int i = 0; i < nfd; ++i)	1613	for (int i = 0; i < nfd; ++i)
1356	{	1614	{
1357	ev_io_init (iow + i, io_cb, fds [i].fd,	1615	ev_io_init (iow + i, io_cb, fds [i].fd,
1358	((fds [i].events & POLLIN ? EV_READ : 0)	1616	((fds [i].events & POLLIN ? EV_READ : 0)
1359	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1617	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1360		1618
1361	fds [i].revents = 0;	1619	fds [i].revents = 0;
1362	iow [i].data = fds + i;
1363	ev_io_start (loop, iow + i);	1620	ev_io_start (loop, iow + i);
1364	}	1621	}
1365	}	1622	}
1366		1623
1367	// stop all watchers after blocking	1624	// stop all watchers after blocking
…		…
1369	adns_check_cb (ev_loop loop, ev_check w, int revents)	1626	adns_check_cb (ev_loop loop, ev_check w, int revents)
1370	{	1627	{
1371	ev_timer_stop (loop, &tw);	1628	ev_timer_stop (loop, &tw);
1372		1629
1373	for (int i = 0; i < nfd; ++i)	1630	for (int i = 0; i < nfd; ++i)
		1631	{
		1632	// set the relevant poll flags
		1633	// could also call adns_processreadable etc. here
		1634	struct pollfd *fd = fds + i;
		1635	int revents = ev_clear_pending (iow + i);
		1636	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1637	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1638
		1639	// now stop the watcher
1374	ev_io_stop (loop, iow + i);	1640	ev_io_stop (loop, iow + i);
		1641	}
1375		1642
1376	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1643	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1644	}
		1645
		1646	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1647	in the prepare watcher and would dispose of the check watcher.
		1648
		1649	Method 3: If the module to be embedded supports explicit event
		1650	notification (adns does), you can also make use of the actual watcher
		1651	callbacks, and only destroy/create the watchers in the prepare watcher.
		1652
		1653	static void
		1654	timer_cb (EV_P_ ev_timer *w, int revents)
		1655	{
		1656	adns_state ads = (adns_state)w->data;
		1657	update_now (EV_A);
		1658
		1659	adns_processtimeouts (ads, &tv_now);
		1660	}
		1661
		1662	static void
		1663	io_cb (EV_P_ ev_io *w, int revents)
		1664	{
		1665	adns_state ads = (adns_state)w->data;
		1666	update_now (EV_A);
		1667
		1668	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1669	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1670	}
		1671
		1672	// do not ever call adns_afterpoll
		1673
		1674	Method 4: Do not use a prepare or check watcher because the module you
		1675	want to embed is too inflexible to support it. Instead, youc na override
		1676	their poll function. The drawback with this solution is that the main
		1677	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1678	this.
		1679
		1680	static gint
		1681	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1682	{
		1683	int got_events = 0;
		1684
		1685	for (n = 0; n < nfds; ++n)
		1686	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1687
		1688	if (timeout >= 0)
		1689	// create/start timer
		1690
		1691	// poll
		1692	ev_loop (EV_A_ 0);
		1693
		1694	// stop timer again
		1695	if (timeout >= 0)
		1696	ev_timer_stop (EV_A_ &to);
		1697
		1698	// stop io watchers again - their callbacks should have set
		1699	for (n = 0; n < nfds; ++n)
		1700	ev_io_stop (EV_A_ iow [n]);
		1701
		1702	return got_events;
1377	}	1703	}
1378		1704
1379		1705
1380	=head2 C<ev_embed> - when one backend isn't enough...	1706	=head2 C<ev_embed> - when one backend isn't enough...
1381		1707
…		…
1445	ev_embed_start (loop_hi, &embed);	1771	ev_embed_start (loop_hi, &embed);
1446	}	1772	}
1447	else	1773	else
1448	loop_lo = loop_hi;	1774	loop_lo = loop_hi;
1449		1775
		1776	=head3 Watcher-Specific Functions and Data Members
		1777
1450	=over 4	1778	=over 4
1451		1779
1452	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1780	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1453		1781
1454	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1782	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)
…		…
1470	The embedded event loop.	1798	The embedded event loop.
1471		1799
1472	=back	1800	=back
1473		1801
1474		1802
		1803	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1804
		1805	Fork watchers are called when a C<fork ()> was detected (usually because
		1806	whoever is a good citizen cared to tell libev about it by calling
		1807	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1808	event loop blocks next and before C<ev_check> watchers are being called,
		1809	and only in the child after the fork. If whoever good citizen calling
		1810	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1811	handlers will be invoked, too, of course.
		1812
		1813	=head3 Watcher-Specific Functions and Data Members
		1814
		1815	=over 4
		1816
		1817	=item ev_fork_init (ev_signal *, callback)
		1818
		1819	Initialises and configures the fork watcher - it has no parameters of any
		1820	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1821	believe me.
		1822
		1823	=back
		1824
		1825
1475	=head1 OTHER FUNCTIONS	1826	=head1 OTHER FUNCTIONS
1476		1827
1477	There are some other functions of possible interest. Described. Here. Now.	1828	There are some other functions of possible interest. Described. Here. Now.
1478		1829
1479	=over 4	1830	=over 4
…		…
1564		1915
1565	To use it,	1916	To use it,
1566		1917
1567	#include <ev++.h>	1918	#include <ev++.h>
1568		1919
1569	(it is not installed by default). This automatically includes F<ev.h>	1920	This automatically includes F<ev.h> and puts all of its definitions (many
1570	and puts all of its definitions (many of them macros) into the global	1921	of them macros) into the global namespace. All C++ specific things are
1571	namespace. All C++ specific things are put into the C<ev> namespace.	1922	put into the C<ev> namespace. It should support all the same embedding
		1923	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1572		1924
1573	It should support all the same embedding options as F<ev.h>, most notably	1925	Care has been taken to keep the overhead low. The only data member the C++
1574	C<EV_MULTIPLICITY>.	1926	classes add (compared to plain C-style watchers) is the event loop pointer
		1927	that the watcher is associated with (or no additional members at all if
		1928	you disable C<EV_MULTIPLICITY> when embedding libev).
		1929
		1930	Currently, functions, and static and non-static member functions can be
		1931	used as callbacks. Other types should be easy to add as long as they only
		1932	need one additional pointer for context. If you need support for other
		1933	types of functors please contact the author (preferably after implementing
		1934	it).
1575		1935
1576	Here is a list of things available in the C<ev> namespace:	1936	Here is a list of things available in the C<ev> namespace:
1577		1937
1578	=over 4	1938	=over 4
1579		1939
…		…
1595		1955
1596	All of those classes have these methods:	1956	All of those classes have these methods:
1597		1957
1598	=over 4	1958	=over 4
1599		1959
1600	=item ev::TYPE::TYPE (object , object::method )	1960	=item ev::TYPE::TYPE ()
1601		1961
1602	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1962	=item ev::TYPE::TYPE (struct ev_loop *)
1603		1963
1604	=item ev::TYPE::~TYPE	1964	=item ev::TYPE::~TYPE
1605		1965
1606	The constructor takes a pointer to an object and a method pointer to	1966	The constructor (optionally) takes an event loop to associate the watcher
1607	the event handler callback to call in this class. The constructor calls	1967	with. If it is omitted, it will use C<EV_DEFAULT>.
1608	C<ev_init> for you, which means you have to call the C<set> method	1968
1609	before starting it. If you do not specify a loop then the constructor	1969	The constructor calls C<ev_init> for you, which means you have to call the
1610	automatically associates the default loop with this watcher.	1970	C<set> method before starting it.
		1971
		1972	It will not set a callback, however: You have to call the templated C<set>
		1973	method to set a callback before you can start the watcher.
		1974
		1975	(The reason why you have to use a method is a limitation in C++ which does
		1976	not allow explicit template arguments for constructors).
1611		1977
1612	The destructor automatically stops the watcher if it is active.	1978	The destructor automatically stops the watcher if it is active.
		1979
		1980	=item w->set<class, &class::method> (object *)
		1981
		1982	This method sets the callback method to call. The method has to have a
		1983	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1984	first argument and the C<revents> as second. The object must be given as
		1985	parameter and is stored in the C<data> member of the watcher.
		1986
		1987	This method synthesizes efficient thunking code to call your method from
		1988	the C callback that libev requires. If your compiler can inline your
		1989	callback (i.e. it is visible to it at the place of the C<set> call and
		1990	your compiler is good :), then the method will be fully inlined into the
		1991	thunking function, making it as fast as a direct C callback.
		1992
		1993	Example: simple class declaration and watcher initialisation
		1994
		1995	struct myclass
		1996	{
		1997	void io_cb (ev::io &w, int revents) { }
		1998	}
		1999
		2000	myclass obj;
		2001	ev::io iow;
		2002	iow.set <myclass, &myclass::io_cb> (&obj);
		2003
		2004	=item w->set<function> (void *data = 0)
		2005
		2006	Also sets a callback, but uses a static method or plain function as
		2007	callback. The optional C<data> argument will be stored in the watcher's
		2008	C<data> member and is free for you to use.
		2009
		2010	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2011
		2012	See the method-C<set> above for more details.
		2013
		2014	Example:
		2015
		2016	static void io_cb (ev::io &w, int revents) { }
		2017	iow.set <io_cb> ();
1613		2018
1614	=item w->set (struct ev_loop *)	2019	=item w->set (struct ev_loop *)
1615		2020
1616	Associates a different C<struct ev_loop> with this watcher. You can only	2021	Associates a different C<struct ev_loop> with this watcher. You can only
1617	do this when the watcher is inactive (and not pending either).	2022	do this when the watcher is inactive (and not pending either).
1618		2023
1619	=item w->set ([args])	2024	=item w->set ([args])
1620		2025
1621	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2026	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1622	called at least once. Unlike the C counterpart, an active watcher gets	2027	called at least once. Unlike the C counterpart, an active watcher gets
1623	automatically stopped and restarted.	2028	automatically stopped and restarted when reconfiguring it with this
		2029	method.
1624		2030
1625	=item w->start ()	2031	=item w->start ()
1626		2032
1627	Starts the watcher. Note that there is no C<loop> argument as the	2033	Starts the watcher. Note that there is no C<loop> argument, as the
1628	constructor already takes the loop.	2034	constructor already stores the event loop.
1629		2035
1630	=item w->stop ()	2036	=item w->stop ()
1631		2037
1632	Stops the watcher if it is active. Again, no C<loop> argument.	2038	Stops the watcher if it is active. Again, no C<loop> argument.
1633		2039
1634	=item w->again () C<ev::timer>, C<ev::periodic> only	2040	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1635		2041
1636	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2042	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1637	C<ev_TYPE_again> function.	2043	C<ev_TYPE_again> function.
1638		2044
1639	=item w->sweep () C<ev::embed> only	2045	=item w->sweep () (C<ev::embed> only)
1640		2046
1641	Invokes C<ev_embed_sweep>.	2047	Invokes C<ev_embed_sweep>.
		2048
		2049	=item w->update () (C<ev::stat> only)
		2050
		2051	Invokes C<ev_stat_stat>.
1642		2052
1643	=back	2053	=back
1644		2054
1645	=back	2055	=back
1646		2056
…		…
1654		2064
1655	myclass ();	2065	myclass ();
1656	}	2066	}
1657		2067
1658	myclass::myclass (int fd)	2068	myclass::myclass (int fd)
1659	: io (this, &myclass::io_cb),
1660	idle (this, &myclass::idle_cb)
1661	{	2069	{
		2070	io .set <myclass, &myclass::io_cb > (this);
		2071	idle.set <myclass, &myclass::idle_cb> (this);
		2072
1662	io.start (fd, ev::READ);	2073	io.start (fd, ev::READ);
1663	}	2074	}
		2075
		2076
		2077	=head1 MACRO MAGIC
		2078
		2079	Libev can be compiled with a variety of options, the most fundamantal
		2080	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
		2081	functions and callbacks have an initial C<struct ev_loop *> argument.
		2082
		2083	To make it easier to write programs that cope with either variant, the
		2084	following macros are defined:
		2085
		2086	=over 4
		2087
		2088	=item C<EV_A>, C<EV_A_>
		2089
		2090	This provides the loop I<argument> for functions, if one is required ("ev
		2091	loop argument"). The C<EV_A> form is used when this is the sole argument,
		2092	C<EV_A_> is used when other arguments are following. Example:
		2093
		2094	ev_unref (EV_A);
		2095	ev_timer_add (EV_A_ watcher);
		2096	ev_loop (EV_A_ 0);
		2097
		2098	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		2099	which is often provided by the following macro.
		2100
		2101	=item C<EV_P>, C<EV_P_>
		2102
		2103	This provides the loop I<parameter> for functions, if one is required ("ev
		2104	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		2105	C<EV_P_> is used when other parameters are following. Example:
		2106
		2107	// this is how ev_unref is being declared
		2108	static void ev_unref (EV_P);
		2109
		2110	// this is how you can declare your typical callback
		2111	static void cb (EV_P_ ev_timer *w, int revents)
		2112
		2113	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		2114	suitable for use with C<EV_A>.
		2115
		2116	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		2117
		2118	Similar to the other two macros, this gives you the value of the default
		2119	loop, if multiple loops are supported ("ev loop default").
		2120
		2121	=back
		2122
		2123	Example: Declare and initialise a check watcher, utilising the above
		2124	macros so it will work regardless of whether multiple loops are supported
		2125	or not.
		2126
		2127	static void
		2128	check_cb (EV_P_ ev_timer *w, int revents)
		2129	{
		2130	ev_check_stop (EV_A_ w);
		2131	}
		2132
		2133	ev_check check;
		2134	ev_check_init (&check, check_cb);
		2135	ev_check_start (EV_DEFAULT_ &check);
		2136	ev_loop (EV_DEFAULT_ 0);
1664		2137
1665	=head1 EMBEDDING	2138	=head1 EMBEDDING
1666		2139
1667	Libev can (and often is) directly embedded into host	2140	Libev can (and often is) directly embedded into host
1668	applications. Examples of applications that embed it include the Deliantra	2141	applications. Examples of applications that embed it include the Deliantra
…		…
1708	ev_vars.h	2181	ev_vars.h
1709	ev_wrap.h	2182	ev_wrap.h
1710		2183
1711	ev_win32.c required on win32 platforms only	2184	ev_win32.c required on win32 platforms only
1712		2185
1713	ev_select.c only when select backend is enabled (which is by default)	2186	ev_select.c only when select backend is enabled (which is enabled by default)
1714	ev_poll.c only when poll backend is enabled (disabled by default)	2187	ev_poll.c only when poll backend is enabled (disabled by default)
1715	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2188	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1716	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2189	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1717	ev_port.c only when the solaris port backend is enabled (disabled by default)	2190	ev_port.c only when the solaris port backend is enabled (disabled by default)
1718		2191
…		…
1843		2316
1844	=item EV_USE_DEVPOLL	2317	=item EV_USE_DEVPOLL
1845		2318
1846	reserved for future expansion, works like the USE symbols above.	2319	reserved for future expansion, works like the USE symbols above.
1847		2320
		2321	=item EV_USE_INOTIFY
		2322
		2323	If defined to be C<1>, libev will compile in support for the Linux inotify
		2324	interface to speed up C<ev_stat> watchers. Its actual availability will
		2325	be detected at runtime.
		2326
1848	=item EV_H	2327	=item EV_H
1849		2328
1850	The name of the F<ev.h> header file used to include it. The default if	2329	The name of the F<ev.h> header file used to include it. The default if
1851	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2330	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1852	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2331	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
1875	will have the C<struct ev_loop *> as first argument, and you can create	2354	will have the C<struct ev_loop *> as first argument, and you can create
1876	additional independent event loops. Otherwise there will be no support	2355	additional independent event loops. Otherwise there will be no support
1877	for multiple event loops and there is no first event loop pointer	2356	for multiple event loops and there is no first event loop pointer
1878	argument. Instead, all functions act on the single default loop.	2357	argument. Instead, all functions act on the single default loop.
1879		2358
		2359	=item EV_MINPRI
		2360
		2361	=item EV_MAXPRI
		2362
		2363	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2364	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2365	provide for more priorities by overriding those symbols (usually defined
		2366	to be C<-2> and C<2>, respectively).
		2367
		2368	When doing priority-based operations, libev usually has to linearly search
		2369	all the priorities, so having many of them (hundreds) uses a lot of space
		2370	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2371	fine.
		2372
		2373	If your embedding app does not need any priorities, defining these both to
		2374	C<0> will save some memory and cpu.
		2375
1880	=item EV_PERIODIC_ENABLE	2376	=item EV_PERIODIC_ENABLE
1881		2377
1882	If undefined or defined to be C<1>, then periodic timers are supported. If	2378	If undefined or defined to be C<1>, then periodic timers are supported. If
1883	defined to be C<0>, then they are not. Disabling them saves a few kB of	2379	defined to be C<0>, then they are not. Disabling them saves a few kB of
1884	code.	2380	code.
1885		2381
		2382	=item EV_IDLE_ENABLE
		2383
		2384	If undefined or defined to be C<1>, then idle watchers are supported. If
		2385	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2386	code.
		2387
1886	=item EV_EMBED_ENABLE	2388	=item EV_EMBED_ENABLE
1887		2389
1888	If undefined or defined to be C<1>, then embed watchers are supported. If	2390	If undefined or defined to be C<1>, then embed watchers are supported. If
1889	defined to be C<0>, then they are not.	2391	defined to be C<0>, then they are not.
1890		2392
1891	=item EV_STAT_ENABLE	2393	=item EV_STAT_ENABLE
1892		2394
1893	If undefined or defined to be C<1>, then stat watchers are supported. If	2395	If undefined or defined to be C<1>, then stat watchers are supported. If
		2396	defined to be C<0>, then they are not.
		2397
		2398	=item EV_FORK_ENABLE
		2399
		2400	If undefined or defined to be C<1>, then fork watchers are supported. If
1894	defined to be C<0>, then they are not.	2401	defined to be C<0>, then they are not.
1895		2402
1896	=item EV_MINIMAL	2403	=item EV_MINIMAL
1897		2404
1898	If you need to shave off some kilobytes of code at the expense of some	2405	If you need to shave off some kilobytes of code at the expense of some
1899	speed, define this symbol to C<1>. Currently only used for gcc to override	2406	speed, define this symbol to C<1>. Currently only used for gcc to override
1900	some inlining decisions, saves roughly 30% codesize of amd64.	2407	some inlining decisions, saves roughly 30% codesize of amd64.
		2408
		2409	=item EV_PID_HASHSIZE
		2410
		2411	C<ev_child> watchers use a small hash table to distribute workload by
		2412	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2413	than enough. If you need to manage thousands of children you might want to
		2414	increase this value (I<must> be a power of two).
		2415
		2416	=item EV_INOTIFY_HASHSIZE
		2417
		2418	C<ev_staz> watchers use a small hash table to distribute workload by
		2419	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2420	usually more than enough. If you need to manage thousands of C<ev_stat>
		2421	watchers you might want to increase this value (I<must> be a power of
		2422	two).
1901		2423
1902	=item EV_COMMON	2424	=item EV_COMMON
1903		2425
1904	By default, all watchers have a C<void *data> member. By redefining	2426	By default, all watchers have a C<void *data> member. By redefining
1905	this macro to a something else you can include more and other types of	2427	this macro to a something else you can include more and other types of
…		…
1934	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2456	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
1935	will be compiled. It is pretty complex because it provides its own header	2457	will be compiled. It is pretty complex because it provides its own header
1936	file.	2458	file.
1937		2459
1938	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2460	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
1939	that everybody includes and which overrides some autoconf choices:	2461	that everybody includes and which overrides some configure choices:
1940		2462
		2463	#define EV_MINIMAL 1
1941	#define EV_USE_POLL 0	2464	#define EV_USE_POLL 0
1942	#define EV_MULTIPLICITY 0	2465	#define EV_MULTIPLICITY 0
1943	#define EV_PERIODICS 0	2466	#define EV_PERIODIC_ENABLE 0
		2467	#define EV_STAT_ENABLE 0
		2468	#define EV_FORK_ENABLE 0
1944	#define EV_CONFIG_H <config.h>	2469	#define EV_CONFIG_H <config.h>
		2470	#define EV_MINPRI 0
		2471	#define EV_MAXPRI 0
1945		2472
1946	#include "ev++.h"	2473	#include "ev++.h"
1947		2474
1948	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2475	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1949		2476
…		…
1955		2482
1956	In this section the complexities of (many of) the algorithms used inside	2483	In this section the complexities of (many of) the algorithms used inside
1957	libev will be explained. For complexity discussions about backends see the	2484	libev will be explained. For complexity discussions about backends see the
1958	documentation for C<ev_default_init>.	2485	documentation for C<ev_default_init>.
1959		2486
		2487	All of the following are about amortised time: If an array needs to be
		2488	extended, libev needs to realloc and move the whole array, but this
		2489	happens asymptotically never with higher number of elements, so O(1) might
		2490	mean it might do a lengthy realloc operation in rare cases, but on average
		2491	it is much faster and asymptotically approaches constant time.
		2492
1960	=over 4	2493	=over 4
1961		2494
1962	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2495	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
1963		2496
		2497	This means that, when you have a watcher that triggers in one hour and
		2498	there are 100 watchers that would trigger before that then inserting will
		2499	have to skip those 100 watchers.
		2500
1964	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2501	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
1965		2502
		2503	That means that for changing a timer costs less than removing/adding them
		2504	as only the relative motion in the event queue has to be paid for.
		2505
1966	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2506	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
1967		2507
		2508	These just add the watcher into an array or at the head of a list.
1968	=item Stopping check/prepare/idle watchers: O(1)	2509	=item Stopping check/prepare/idle watchers: O(1)
1969		2510
1970	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2511	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2512
		2513	These watchers are stored in lists then need to be walked to find the
		2514	correct watcher to remove. The lists are usually short (you don't usually
		2515	have many watchers waiting for the same fd or signal).
1971		2516
1972	=item Finding the next timer per loop iteration: O(1)	2517	=item Finding the next timer per loop iteration: O(1)
1973		2518
1974	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2519	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
1975		2520
		2521	A change means an I/O watcher gets started or stopped, which requires
		2522	libev to recalculate its status (and possibly tell the kernel).
		2523
1976	=item Activating one watcher: O(1)	2524	=item Activating one watcher: O(1)
1977		2525
		2526	=item Priority handling: O(number_of_priorities)
		2527
		2528	Priorities are implemented by allocating some space for each
		2529	priority. When doing priority-based operations, libev usually has to
		2530	linearly search all the priorities.
		2531
1978	=back	2532	=back
1979		2533
1980		2534
1981	=head1 AUTHOR	2535	=head1 AUTHOR
1982		2536

Diff Legend

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

Comparing libev/ev.pod (file contents): Revision 1.48 by root, Tue Nov 27 08:11:52 2007 UTC vs. Revision 1.88 by ayin, Tue Dec 18 13:06:18 2007 UTC

Diff Legend

Comparing libev/ev.pod (file contents):
Revision 1.48 by root, Tue Nov 27 08:11:52 2007 UTC vs.
Revision 1.88 by ayin, Tue Dec 18 13:06:18 2007 UTC