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

Comparing libev/ev.pod (file contents):
Revision 1.46 by root, Mon Nov 26 10:20:43 2007 UTC vs.
Revision 1.80 by root, Sun Dec 9 19:47:30 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 such.
52		104
53
54	=head1 GLOBAL FUNCTIONS	105	=head1 GLOBAL FUNCTIONS
55		106
56	These functions can be called anytime, even before initialising the	107	These functions can be called anytime, even before initialising the
57	library in any way.	108	library in any way.
58		109
…		…
66		117
67	=item int ev_version_major ()	118	=item int ev_version_major ()
68		119
69	=item int ev_version_minor ()	120	=item int ev_version_minor ()
70		121
71	You can find out the major and minor version numbers of the library	122	You can find out the major and minor ABI version numbers of the library
72	you linked against by calling the functions C<ev_version_major> and	123	you linked against by calling the functions C<ev_version_major> and
73	C<ev_version_minor>. If you want, you can compare against the global	124	C<ev_version_minor>. If you want, you can compare against the global
74	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	125	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
75	version of the library your program was compiled against.	126	version of the library your program was compiled against.
76		127
		128	These version numbers refer to the ABI version of the library, not the
		129	release version.
		130
77	Usually, it's a good idea to terminate if the major versions mismatch,	131	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	132	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	133	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	134	not a problem.
81		135
82	Example: make sure we haven't accidentally been linked against the wrong	136	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	137	version.
84		138
85	assert (("libev version mismatch",	139	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	140	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	141	&& ev_version_minor () >= EV_VERSION_MINOR));
88		142
…		…
118		172
119	See the description of C<ev_embed> watchers for more info.	173	See the description of C<ev_embed> watchers for more info.
120		174
121	=item ev_set_allocator (void (cb)(void *ptr, long size))	175	=item ev_set_allocator (void (cb)(void *ptr, long size))
122		176
123	Sets the allocation function to use (the prototype is similar to the	177	Sets the allocation function to use (the prototype is similar - the
124	realloc C function, the semantics are identical). It is used to allocate	178	semantics is identical - to the realloc C function). It is used to
125	and free memory (no surprises here). If it returns zero when memory	179	allocate and free memory (no surprises here). If it returns zero when
126	needs to be allocated, the library might abort or take some potentially	180	memory needs to be allocated, the library might abort or take some
127	destructive action. The default is your system realloc function.	181	potentially destructive action. The default is your system realloc
		182	function.
128		183
129	You could override this function in high-availability programs to, say,	184	You could override this function in high-availability programs to, say,
130	free some memory if it cannot allocate memory, to use a special allocator,	185	free some memory if it cannot allocate memory, to use a special allocator,
131	or even to sleep a while and retry until some memory is available.	186	or even to sleep a while and retry until some memory is available.
132		187
133	Example: replace the libev allocator with one that waits a bit and then	188	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	189	retries).
135		190
136	static void *	191	static void *
137	persistent_realloc (void *ptr, long size)	192	persistent_realloc (void *ptr, size_t size)
138	{	193	{
139	for (;;)	194	for (;;)
140	{	195	{
141	void *newptr = realloc (ptr, size);	196	void *newptr = realloc (ptr, size);
142		197
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	213	callback is set, then libev will expect it to remedy the sitution, no
159	matter what, when it returns. That is, libev will generally retry the	214	matter what, when it returns. That is, libev will generally retry the
160	requested operation, or, if the condition doesn't go away, do bad stuff	215	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	216	(such as abort).
162		217
163	Example: do the same thing as libev does internally:	218	Example: This is basically the same thing that libev does internally, too.
164		219
165	static void	220	static void
166	fatal_error (const char *msg)	221	fatal_error (const char *msg)
167	{	222	{
168	perror (msg);	223	perror (msg);
…		…
218	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	273	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
219	override the flags completely if it is found in the environment. This is	274	override the flags completely if it is found in the environment. This is
220	useful to try out specific backends to test their performance, or to work	275	useful to try out specific backends to test their performance, or to work
221	around bugs.	276	around bugs.
222		277
		278	=item C<EVFLAG_FORKCHECK>
		279
		280	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		281	a fork, you can also make libev check for a fork in each iteration by
		282	enabling this flag.
		283
		284	This works by calling C<getpid ()> on every iteration of the loop,
		285	and thus this might slow down your event loop if you do a lot of loop
		286	iterations and little real work, but is usually not noticeable (on my
		287	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		288	without a syscall and thus I<very> fast, but my Linux system also has
		289	C<pthread_atfork> which is even faster).
		290
		291	The big advantage of this flag is that you can forget about fork (and
		292	forget about forgetting to tell libev about forking) when you use this
		293	flag.
		294
		295	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		296	environment variable.
		297
223	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	298	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
224		299
225	This is your standard select(2) backend. Not I<completely> standard, as	300	This is your standard select(2) backend. Not I<completely> standard, as
226	libev tries to roll its own fd_set with no limits on the number of fds,	301	libev tries to roll its own fd_set with no limits on the number of fds,
227	but if that fails, expect a fairly low limit on the number of fds when	302	but if that fails, expect a fairly low limit on the number of fds when
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	389	Similar to C<ev_default_loop>, but always creates a new event loop that is
315	always distinct from the default loop. Unlike the default loop, it cannot	390	always distinct from the default loop. Unlike the default loop, it cannot
316	handle signal and child watchers, and attempts to do so will be greeted by	391	handle signal and child watchers, and attempts to do so will be greeted by
317	undefined behaviour (or a failed assertion if assertions are enabled).	392	undefined behaviour (or a failed assertion if assertions are enabled).
318		393
319	Example: try to create a event loop that uses epoll and nothing else.	394	Example: Try to create a event loop that uses epoll and nothing else.
320		395
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	396	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
322	if (!epoller)	397	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	398	fatal ("no epoll found here, maybe it hides under your chair");
324		399
…		…
362		437
363	Like C<ev_default_fork>, but acts on an event loop created by	438	Like C<ev_default_fork>, but acts on an event loop created by
364	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	439	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
365	after fork, and how you do this is entirely your own problem.	440	after fork, and how you do this is entirely your own problem.
366		441
		442	=item unsigned int ev_loop_count (loop)
		443
		444	Returns the count of loop iterations for the loop, which is identical to
		445	the number of times libev did poll for new events. It starts at C<0> and
		446	happily wraps around with enough iterations.
		447
		448	This value can sometimes be useful as a generation counter of sorts (it
		449	"ticks" the number of loop iterations), as it roughly corresponds with
		450	C<ev_prepare> and C<ev_check> calls.
		451
367	=item unsigned int ev_backend (loop)	452	=item unsigned int ev_backend (loop)
368		453
369	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	454	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
370	use.	455	use.
371		456
…		…
404	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	489	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
405	usually a better approach for this kind of thing.	490	usually a better approach for this kind of thing.
406		491
407	Here are the gory details of what C<ev_loop> does:	492	Here are the gory details of what C<ev_loop> does:
408		493
		494	- Before the first iteration, call any pending watchers.
409	* If there are no active watchers (reference count is zero), return.	495	* If there are no active watchers (reference count is zero), return.
410	- Queue prepare watchers and then call all outstanding watchers.	496	- Queue all prepare watchers and then call all outstanding watchers.
411	- If we have been forked, recreate the kernel state.	497	- If we have been forked, recreate the kernel state.
412	- Update the kernel state with all outstanding changes.	498	- Update the kernel state with all outstanding changes.
413	- Update the "event loop time".	499	- Update the "event loop time".
414	- Calculate for how long to block.	500	- Calculate for how long to block.
415	- Block the process, waiting for any events.	501	- Block the process, waiting for any events.
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	509	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	510	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	511	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	512	were used, return, otherwise continue with step *.
427		513
428	Example: queue some jobs and then loop until no events are outsanding	514	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	515	anymore.
430		516
431	... queue jobs here, make sure they register event watchers as long	517	... queue jobs here, make sure they register event watchers as long
432	... as they still have work to do (even an idle watcher will do..)	518	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	519	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	539	visible to the libev user and should not keep C<ev_loop> from exiting if
454	no event watchers registered by it are active. It is also an excellent	540	no event watchers registered by it are active. It is also an excellent
455	way to do this for generic recurring timers or from within third-party	541	way to do this for generic recurring timers or from within third-party
456	libraries. Just remember to I<unref after start> and I<ref before stop>.	542	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		543
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	544	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	545	running when nothing else is active.
460		546
461	struct dv_signal exitsig;	547	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	548	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	549	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	550	evf_unref (loop);
465		551
466	Example: for some weird reason, unregister the above signal handler again.	552	Example: For some weird reason, unregister the above signal handler again.
467		553
468	ev_ref (myloop);	554	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	555	ev_signal_stop (loop, &exitsig);
470		556
471	=back	557	=back
472		558
473		559
474	=head1 ANATOMY OF A WATCHER	560	=head1 ANATOMY OF A WATCHER
…		…
544	The signal specified in the C<ev_signal> watcher has been received by a thread.	630	The signal specified in the C<ev_signal> watcher has been received by a thread.
545		631
546	=item C<EV_CHILD>	632	=item C<EV_CHILD>
547		633
548	The pid specified in the C<ev_child> watcher has received a status change.	634	The pid specified in the C<ev_child> watcher has received a status change.
		635
		636	=item C<EV_STAT>
		637
		638	The path specified in the C<ev_stat> watcher changed its attributes somehow.
549		639
550	=item C<EV_IDLE>	640	=item C<EV_IDLE>
551		641
552	The C<ev_idle> watcher has determined that you have nothing better to do.	642	The C<ev_idle> watcher has determined that you have nothing better to do.
553		643
…		…
561	received events. Callbacks of both watcher types can start and stop as	651	received events. Callbacks of both watcher types can start and stop as
562	many watchers as they want, and all of them will be taken into account	652	many watchers as they want, and all of them will be taken into account
563	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	653	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
564	C<ev_loop> from blocking).	654	C<ev_loop> from blocking).
565		655
		656	=item C<EV_EMBED>
		657
		658	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		659
		660	=item C<EV_FORK>
		661
		662	The event loop has been resumed in the child process after fork (see
		663	C<ev_fork>).
		664
566	=item C<EV_ERROR>	665	=item C<EV_ERROR>
567		666
568	An unspecified error has occured, the watcher has been stopped. This might	667	An unspecified error has occured, the watcher has been stopped. This might
569	happen because the watcher could not be properly started because libev	668	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	669	ran out of memory, a file descriptor was found to be closed or any other
…		…
641	=item bool ev_is_pending (ev_TYPE *watcher)	740	=item bool ev_is_pending (ev_TYPE *watcher)
642		741
643	Returns a true value iff the watcher is pending, (i.e. it has outstanding	742	Returns a true value iff the watcher is pending, (i.e. it has outstanding
644	events but its callback has not yet been invoked). As long as a watcher	743	events but its callback has not yet been invoked). As long as a watcher
645	is pending (but not active) you must not call an init function on it (but	744	is pending (but not active) you must not call an init function on it (but
646	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	745	C<ev_TYPE_set> is safe), you must not change its priority, and you must
647	libev (e.g. you cnanot C<free ()> it).	746	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		747	it).
648		748
649	=item callback = ev_cb (ev_TYPE *watcher)	749	=item callback ev_cb (ev_TYPE *watcher)
650		750
651	Returns the callback currently set on the watcher.	751	Returns the callback currently set on the watcher.
652		752
653	=item ev_cb_set (ev_TYPE *watcher, callback)	753	=item ev_cb_set (ev_TYPE *watcher, callback)
654		754
655	Change the callback. You can change the callback at virtually any time	755	Change the callback. You can change the callback at virtually any time
656	(modulo threads).	756	(modulo threads).
		757
		758	=item ev_set_priority (ev_TYPE *watcher, priority)
		759
		760	=item int ev_priority (ev_TYPE *watcher)
		761
		762	Set and query the priority of the watcher. The priority is a small
		763	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		764	(default: C<-2>). Pending watchers with higher priority will be invoked
		765	before watchers with lower priority, but priority will not keep watchers
		766	from being executed (except for C<ev_idle> watchers).
		767
		768	This means that priorities are I<only> used for ordering callback
		769	invocation after new events have been received. This is useful, for
		770	example, to reduce latency after idling, or more often, to bind two
		771	watchers on the same event and make sure one is called first.
		772
		773	If you need to suppress invocation when higher priority events are pending
		774	you need to look at C<ev_idle> watchers, which provide this functionality.
		775
		776	You I<must not> change the priority of a watcher as long as it is active or
		777	pending.
		778
		779	The default priority used by watchers when no priority has been set is
		780	always C<0>, which is supposed to not be too high and not be too low :).
		781
		782	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		783	fine, as long as you do not mind that the priority value you query might
		784	or might not have been adjusted to be within valid range.
		785
		786	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		787
		788	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		789	C<loop> nor C<revents> need to be valid as long as the watcher callback
		790	can deal with that fact.
		791
		792	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		793
		794	If the watcher is pending, this function returns clears its pending status
		795	and returns its C<revents> bitset (as if its callback was invoked). If the
		796	watcher isn't pending it does nothing and returns C<0>.
657		797
658	=back	798	=back
659		799
660		800
661	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	801	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
682	{	822	{
683	struct my_io w = (struct my_io )w_;	823	struct my_io w = (struct my_io )w_;
684	...	824	...
685	}	825	}
686		826
687	More interesting and less C-conformant ways of catsing your callback type	827	More interesting and less C-conformant ways of casting your callback type
688	have been omitted....	828	instead have been omitted.
		829
		830	Another common scenario is having some data structure with multiple
		831	watchers:
		832
		833	struct my_biggy
		834	{
		835	int some_data;
		836	ev_timer t1;
		837	ev_timer t2;
		838	}
		839
		840	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		841	you need to use C<offsetof>:
		842
		843	#include <stddef.h>
		844
		845	static void
		846	t1_cb (EV_P_ struct ev_timer *w, int revents)
		847	{
		848	struct my_biggy big = (struct my_biggy *
		849	(((char *)w) - offsetof (struct my_biggy, t1));
		850	}
		851
		852	static void
		853	t2_cb (EV_P_ struct ev_timer *w, int revents)
		854	{
		855	struct my_biggy big = (struct my_biggy *
		856	(((char *)w) - offsetof (struct my_biggy, t2));
		857	}
689		858
690		859
691	=head1 WATCHER TYPES	860	=head1 WATCHER TYPES
692		861
693	This section describes each watcher in detail, but will not repeat	862	This section describes each watcher in detail, but will not repeat
694	information given in the last section.	863	information given in the last section. Any initialisation/set macros,
		864	functions and members specific to the watcher type are explained.
		865
		866	Members are additionally marked with either I<[read-only]>, meaning that,
		867	while the watcher is active, you can look at the member and expect some
		868	sensible content, but you must not modify it (you can modify it while the
		869	watcher is stopped to your hearts content), or I<[read-write]>, which
		870	means you can expect it to have some sensible content while the watcher
		871	is active, but you can also modify it. Modifying it may not do something
		872	sensible or take immediate effect (or do anything at all), but libev will
		873	not crash or malfunction in any way.
695		874
696		875
697	=head2 C<ev_io> - is this file descriptor readable or writable?	876	=head2 C<ev_io> - is this file descriptor readable or writable?
698		877
699	I/O watchers check whether a file descriptor is readable or writable	878	I/O watchers check whether a file descriptor is readable or writable
…		…
728	it is best to always use non-blocking I/O: An extra C<read>(2) returning	907	it is best to always use non-blocking I/O: An extra C<read>(2) returning
729	C<EAGAIN> is far preferable to a program hanging until some data arrives.	908	C<EAGAIN> is far preferable to a program hanging until some data arrives.
730		909
731	If you cannot run the fd in non-blocking mode (for example you should not	910	If you cannot run the fd in non-blocking mode (for example you should not
732	play around with an Xlib connection), then you have to seperately re-test	911	play around with an Xlib connection), then you have to seperately re-test
733	wether a file descriptor is really ready with a known-to-be good interface	912	whether a file descriptor is really ready with a known-to-be good interface
734	such as poll (fortunately in our Xlib example, Xlib already does this on	913	such as poll (fortunately in our Xlib example, Xlib already does this on
735	its own, so its quite safe to use).	914	its own, so its quite safe to use).
736		915
737	=over 4	916	=over 4
738		917
…		…
742		921
743	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	922	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
744	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	923	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
745	C<EV_READ \| EV_WRITE> to receive the given events.	924	C<EV_READ \| EV_WRITE> to receive the given events.
746		925
		926	=item int fd [read-only]
		927
		928	The file descriptor being watched.
		929
		930	=item int events [read-only]
		931
		932	The events being watched.
		933
747	=back	934	=back
748		935
749	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	936	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
750	readable, but only once. Since it is likely line-buffered, you could	937	readable, but only once. Since it is likely line-buffered, you could
751	attempt to read a whole line in the callback:	938	attempt to read a whole line in the callback.
752		939
753	static void	940	static void
754	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	941	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
755	{	942	{
756	ev_io_stop (loop, w);	943	ev_io_stop (loop, w);
…		…
808	=item ev_timer_again (loop)	995	=item ev_timer_again (loop)
809		996
810	This will act as if the timer timed out and restart it again if it is	997	This will act as if the timer timed out and restart it again if it is
811	repeating. The exact semantics are:	998	repeating. The exact semantics are:
812		999
		1000	If the timer is pending, its pending status is cleared.
		1001
813	If the timer is started but nonrepeating, stop it.	1002	If the timer is started but nonrepeating, stop it (as if it timed out).
814		1003
815	If the timer is repeating, either start it if necessary (with the repeat	1004	If the timer is repeating, either start it if necessary (with the
816	value), or reset the running timer to the repeat value.	1005	C<repeat> value), or reset the running timer to the C<repeat> value.
817		1006
818	This sounds a bit complicated, but here is a useful and typical	1007	This sounds a bit complicated, but here is a useful and typical
819	example: Imagine you have a tcp connection and you want a so-called idle	1008	example: Imagine you have a tcp connection and you want a so-called idle
820	timeout, that is, you want to be called when there have been, say, 60	1009	timeout, that is, you want to be called when there have been, say, 60
821	seconds of inactivity on the socket. The easiest way to do this is to	1010	seconds of inactivity on the socket. The easiest way to do this is to
822	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each	1011	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
823	time you successfully read or write some data. If you go into an idle	1012	C<ev_timer_again> each time you successfully read or write some data. If
824	state where you do not expect data to travel on the socket, you can stop	1013	you go into an idle state where you do not expect data to travel on the
825	the timer, and again will automatically restart it if need be.	1014	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
		1015	automatically restart it if need be.
		1016
		1017	That means you can ignore the C<after> value and C<ev_timer_start>
		1018	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
		1019
		1020	ev_timer_init (timer, callback, 0., 5.);
		1021	ev_timer_again (loop, timer);
		1022	...
		1023	timer->again = 17.;
		1024	ev_timer_again (loop, timer);
		1025	...
		1026	timer->again = 10.;
		1027	ev_timer_again (loop, timer);
		1028
		1029	This is more slightly efficient then stopping/starting the timer each time
		1030	you want to modify its timeout value.
		1031
		1032	=item ev_tstamp repeat [read-write]
		1033
		1034	The current C<repeat> value. Will be used each time the watcher times out
		1035	or C<ev_timer_again> is called and determines the next timeout (if any),
		1036	which is also when any modifications are taken into account.
826		1037
827	=back	1038	=back
828		1039
829	Example: create a timer that fires after 60 seconds.	1040	Example: Create a timer that fires after 60 seconds.
830		1041
831	static void	1042	static void
832	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1043	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
833	{	1044	{
834	.. one minute over, w is actually stopped right here	1045	.. one minute over, w is actually stopped right here
…		…
836		1047
837	struct ev_timer mytimer;	1048	struct ev_timer mytimer;
838	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1049	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
839	ev_timer_start (loop, &mytimer);	1050	ev_timer_start (loop, &mytimer);
840		1051
841	Example: create a timeout timer that times out after 10 seconds of	1052	Example: Create a timeout timer that times out after 10 seconds of
842	inactivity.	1053	inactivity.
843		1054
844	static void	1055	static void
845	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1056	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
846	{	1057	{
…		…
866	but on wallclock time (absolute time). You can tell a periodic watcher	1077	but on wallclock time (absolute time). You can tell a periodic watcher
867	to trigger "at" some specific point in time. For example, if you tell a	1078	to trigger "at" some specific point in time. For example, if you tell a
868	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1079	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
869	+ 10.>) and then reset your system clock to the last year, then it will	1080	+ 10.>) and then reset your system clock to the last year, then it will
870	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1081	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
871	roughly 10 seconds later and of course not if you reset your system time	1082	roughly 10 seconds later).
872	again).
873		1083
874	They can also be used to implement vastly more complex timers, such as	1084	They can also be used to implement vastly more complex timers, such as
875	triggering an event on eahc midnight, local time.	1085	triggering an event on each midnight, local time or other, complicated,
		1086	rules.
876		1087
877	As with timers, the callback is guarenteed to be invoked only when the	1088	As with timers, the callback is guarenteed to be invoked only when the
878	time (C<at>) has been passed, but if multiple periodic timers become ready	1089	time (C<at>) has been passed, but if multiple periodic timers become ready
879	during the same loop iteration then order of execution is undefined.	1090	during the same loop iteration then order of execution is undefined.
880		1091
…		…
887	Lots of arguments, lets sort it out... There are basically three modes of	1098	Lots of arguments, lets sort it out... There are basically three modes of
888	operation, and we will explain them from simplest to complex:	1099	operation, and we will explain them from simplest to complex:
889		1100
890	=over 4	1101	=over 4
891		1102
892	=item * absolute timer (interval = reschedule_cb = 0)	1103	=item * absolute timer (at = time, interval = reschedule_cb = 0)
893		1104
894	In this configuration the watcher triggers an event at the wallclock time	1105	In this configuration the watcher triggers an event at the wallclock time
895	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1106	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
896	that is, if it is to be run at January 1st 2011 then it will run when the	1107	that is, if it is to be run at January 1st 2011 then it will run when the
897	system time reaches or surpasses this time.	1108	system time reaches or surpasses this time.
898		1109
899	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1110	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
900		1111
901	In this mode the watcher will always be scheduled to time out at the next	1112	In this mode the watcher will always be scheduled to time out at the next
902	C<at + N * interval> time (for some integer N) and then repeat, regardless	1113	C<at + N * interval> time (for some integer N, which can also be negative)
903	of any time jumps.	1114	and then repeat, regardless of any time jumps.
904		1115
905	This can be used to create timers that do not drift with respect to system	1116	This can be used to create timers that do not drift with respect to system
906	time:	1117	time:
907		1118
908	ev_periodic_set (&periodic, 0., 3600., 0);	1119	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
914		1125
915	Another way to think about it (for the mathematically inclined) is that	1126	Another way to think about it (for the mathematically inclined) is that
916	C<ev_periodic> will try to run the callback in this mode at the next possible	1127	C<ev_periodic> will try to run the callback in this mode at the next possible
917	time where C<time = at (mod interval)>, regardless of any time jumps.	1128	time where C<time = at (mod interval)>, regardless of any time jumps.
918		1129
		1130	For numerical stability it is preferable that the C<at> value is near
		1131	C<ev_now ()> (the current time), but there is no range requirement for
		1132	this value.
		1133
919	=item * manual reschedule mode (reschedule_cb = callback)	1134	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
920		1135
921	In this mode the values for C<interval> and C<at> are both being	1136	In this mode the values for C<interval> and C<at> are both being
922	ignored. Instead, each time the periodic watcher gets scheduled, the	1137	ignored. Instead, each time the periodic watcher gets scheduled, the
923	reschedule callback will be called with the watcher as first, and the	1138	reschedule callback will be called with the watcher as first, and the
924	current time as second argument.	1139	current time as second argument.
925		1140
926	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1141	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
927	ever, or make any event loop modifications>. If you need to stop it,	1142	ever, or make any event loop modifications>. If you need to stop it,
928	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1143	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
929	starting a prepare watcher).	1144	starting an C<ev_prepare> watcher, which is legal).
930		1145
931	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1146	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
932	ev_tstamp now)>, e.g.:	1147	ev_tstamp now)>, e.g.:
933		1148
934	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1149	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
957	Simply stops and restarts the periodic watcher again. This is only useful	1172	Simply stops and restarts the periodic watcher again. This is only useful
958	when you changed some parameters or the reschedule callback would return	1173	when you changed some parameters or the reschedule callback would return
959	a different time than the last time it was called (e.g. in a crond like	1174	a different time than the last time it was called (e.g. in a crond like
960	program when the crontabs have changed).	1175	program when the crontabs have changed).
961		1176
		1177	=item ev_tstamp offset [read-write]
		1178
		1179	When repeating, this contains the offset value, otherwise this is the
		1180	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1181
		1182	Can be modified any time, but changes only take effect when the periodic
		1183	timer fires or C<ev_periodic_again> is being called.
		1184
		1185	=item ev_tstamp interval [read-write]
		1186
		1187	The current interval value. Can be modified any time, but changes only
		1188	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1189	called.
		1190
		1191	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
		1192
		1193	The current reschedule callback, or C<0>, if this functionality is
		1194	switched off. Can be changed any time, but changes only take effect when
		1195	the periodic timer fires or C<ev_periodic_again> is being called.
		1196
962	=back	1197	=back
963		1198
964	Example: call a callback every hour, or, more precisely, whenever the	1199	Example: Call a callback every hour, or, more precisely, whenever the
965	system clock is divisible by 3600. The callback invocation times have	1200	system clock is divisible by 3600. The callback invocation times have
966	potentially a lot of jittering, but good long-term stability.	1201	potentially a lot of jittering, but good long-term stability.
967		1202
968	static void	1203	static void
969	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1204	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
973		1208
974	struct ev_periodic hourly_tick;	1209	struct ev_periodic hourly_tick;
975	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1210	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
976	ev_periodic_start (loop, &hourly_tick);	1211	ev_periodic_start (loop, &hourly_tick);
977		1212
978	Example: the same as above, but use a reschedule callback to do it:	1213	Example: The same as above, but use a reschedule callback to do it:
979		1214
980	#include <math.h>	1215	#include <math.h>
981		1216
982	static ev_tstamp	1217	static ev_tstamp
983	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1218	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
985	return fmod (now, 3600.) + 3600.;	1220	return fmod (now, 3600.) + 3600.;
986	}	1221	}
987		1222
988	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1223	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
989		1224
990	Example: call a callback every hour, starting now:	1225	Example: Call a callback every hour, starting now:
991		1226
992	struct ev_periodic hourly_tick;	1227	struct ev_periodic hourly_tick;
993	ev_periodic_init (&hourly_tick, clock_cb,	1228	ev_periodic_init (&hourly_tick, clock_cb,
994	fmod (ev_now (loop), 3600.), 3600., 0);	1229	fmod (ev_now (loop), 3600.), 3600., 0);
995	ev_periodic_start (loop, &hourly_tick);	1230	ev_periodic_start (loop, &hourly_tick);
…		…
1016	=item ev_signal_set (ev_signal *, int signum)	1251	=item ev_signal_set (ev_signal *, int signum)
1017		1252
1018	Configures the watcher to trigger on the given signal number (usually one	1253	Configures the watcher to trigger on the given signal number (usually one
1019	of the C<SIGxxx> constants).	1254	of the C<SIGxxx> constants).
1020		1255
		1256	=item int signum [read-only]
		1257
		1258	The signal the watcher watches out for.
		1259
1021	=back	1260	=back
1022		1261
1023		1262
1024	=head2 C<ev_child> - watch out for process status changes	1263	=head2 C<ev_child> - watch out for process status changes
1025		1264
…		…
1037	at the C<rstatus> member of the C<ev_child> watcher structure to see	1276	at the C<rstatus> member of the C<ev_child> watcher structure to see
1038	the status word (use the macros from C<sys/wait.h> and see your systems	1277	the status word (use the macros from C<sys/wait.h> and see your systems
1039	C<waitpid> documentation). The C<rpid> member contains the pid of the	1278	C<waitpid> documentation). The C<rpid> member contains the pid of the
1040	process causing the status change.	1279	process causing the status change.
1041		1280
		1281	=item int pid [read-only]
		1282
		1283	The process id this watcher watches out for, or C<0>, meaning any process id.
		1284
		1285	=item int rpid [read-write]
		1286
		1287	The process id that detected a status change.
		1288
		1289	=item int rstatus [read-write]
		1290
		1291	The process exit/trace status caused by C<rpid> (see your systems
		1292	C<waitpid> and C<sys/wait.h> documentation for details).
		1293
1042	=back	1294	=back
1043		1295
1044	Example: try to exit cleanly on SIGINT and SIGTERM.	1296	Example: Try to exit cleanly on SIGINT and SIGTERM.
1045		1297
1046	static void	1298	static void
1047	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1299	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1048	{	1300	{
1049	ev_unloop (loop, EVUNLOOP_ALL);	1301	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1052	struct ev_signal signal_watcher;	1304	struct ev_signal signal_watcher;
1053	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1305	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1054	ev_signal_start (loop, &sigint_cb);	1306	ev_signal_start (loop, &sigint_cb);
1055		1307
1056		1308
		1309	=head2 C<ev_stat> - did the file attributes just change?
		1310
		1311	This watches a filesystem path for attribute changes. That is, it calls
		1312	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1313	compared to the last time, invoking the callback if it did.
		1314
		1315	The path does not need to exist: changing from "path exists" to "path does
		1316	not exist" is a status change like any other. The condition "path does
		1317	not exist" is signified by the C<st_nlink> field being zero (which is
		1318	otherwise always forced to be at least one) and all the other fields of
		1319	the stat buffer having unspecified contents.
		1320
		1321	The path I<should> be absolute and I<must not> end in a slash. If it is
		1322	relative and your working directory changes, the behaviour is undefined.
		1323
		1324	Since there is no standard to do this, the portable implementation simply
		1325	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1326	can specify a recommended polling interval for this case. If you specify
		1327	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1328	unspecified default> value will be used (which you can expect to be around
		1329	five seconds, although this might change dynamically). Libev will also
		1330	impose a minimum interval which is currently around C<0.1>, but thats
		1331	usually overkill.
		1332
		1333	This watcher type is not meant for massive numbers of stat watchers,
		1334	as even with OS-supported change notifications, this can be
		1335	resource-intensive.
		1336
		1337	At the time of this writing, only the Linux inotify interface is
		1338	implemented (implementing kqueue support is left as an exercise for the
		1339	reader). Inotify will be used to give hints only and should not change the
		1340	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1341	to fall back to regular polling again even with inotify, but changes are
		1342	usually detected immediately, and if the file exists there will be no
		1343	polling.
		1344
		1345	=over 4
		1346
		1347	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
		1348
		1349	=item ev_stat_set (ev_stat , const char path, ev_tstamp interval)
		1350
		1351	Configures the watcher to wait for status changes of the given
		1352	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1353	be detected and should normally be specified as C<0> to let libev choose
		1354	a suitable value. The memory pointed to by C<path> must point to the same
		1355	path for as long as the watcher is active.
		1356
		1357	The callback will be receive C<EV_STAT> when a change was detected,
		1358	relative to the attributes at the time the watcher was started (or the
		1359	last change was detected).
		1360
		1361	=item ev_stat_stat (ev_stat *)
		1362
		1363	Updates the stat buffer immediately with new values. If you change the
		1364	watched path in your callback, you could call this fucntion to avoid
		1365	detecting this change (while introducing a race condition). Can also be
		1366	useful simply to find out the new values.
		1367
		1368	=item ev_statdata attr [read-only]
		1369
		1370	The most-recently detected attributes of the file. Although the type is of
		1371	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1372	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1373	was some error while C<stat>ing the file.
		1374
		1375	=item ev_statdata prev [read-only]
		1376
		1377	The previous attributes of the file. The callback gets invoked whenever
		1378	C<prev> != C<attr>.
		1379
		1380	=item ev_tstamp interval [read-only]
		1381
		1382	The specified interval.
		1383
		1384	=item const char *path [read-only]
		1385
		1386	The filesystem path that is being watched.
		1387
		1388	=back
		1389
		1390	Example: Watch C</etc/passwd> for attribute changes.
		1391
		1392	static void
		1393	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1394	{
		1395	/* /etc/passwd changed in some way */
		1396	if (w->attr.st_nlink)
		1397	{
		1398	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1399	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1400	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1401	}
		1402	else
		1403	/* you shalt not abuse printf for puts */
		1404	puts ("wow, /etc/passwd is not there, expect problems. "
		1405	"if this is windows, they already arrived\n");
		1406	}
		1407
		1408	...
		1409	ev_stat passwd;
		1410
		1411	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1412	ev_stat_start (loop, &passwd);
		1413
		1414
1057	=head2 C<ev_idle> - when you've got nothing better to do...	1415	=head2 C<ev_idle> - when you've got nothing better to do...
1058		1416
1059	Idle watchers trigger events when there are no other events are pending	1417	Idle watchers trigger events when no other events of the same or higher
1060	(prepare, check and other idle watchers do not count). That is, as long	1418	priority are pending (prepare, check and other idle watchers do not
1061	as your process is busy handling sockets or timeouts (or even signals,	1419	count).
1062	imagine) it will not be triggered. But when your process is idle all idle	1420
1063	watchers are being called again and again, once per event loop iteration -	1421	That is, as long as your process is busy handling sockets or timeouts
		1422	(or even signals, imagine) of the same or higher priority it will not be
		1423	triggered. But when your process is idle (or only lower-priority watchers
		1424	are pending), the idle watchers are being called once per event loop
1064	until stopped, that is, or your process receives more events and becomes	1425	iteration - until stopped, that is, or your process receives more events
1065	busy.	1426	and becomes busy again with higher priority stuff.
1066		1427
1067	The most noteworthy effect is that as long as any idle watchers are	1428	The most noteworthy effect is that as long as any idle watchers are
1068	active, the process will not block when waiting for new events.	1429	active, the process will not block when waiting for new events.
1069		1430
1070	Apart from keeping your process non-blocking (which is a useful	1431	Apart from keeping your process non-blocking (which is a useful
…		…
1080	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1441	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1081	believe me.	1442	believe me.
1082		1443
1083	=back	1444	=back
1084		1445
1085	Example: dynamically allocate an C<ev_idle>, start it, and in the	1446	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1086	callback, free it. Alos, use no error checking, as usual.	1447	callback, free it. Also, use no error checking, as usual.
1087		1448
1088	static void	1449	static void
1089	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1450	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1090	{	1451	{
1091	free (w);	1452	free (w);
…		…
1136	with priority higher than or equal to the event loop and one coroutine	1497	with priority higher than or equal to the event loop and one coroutine
1137	of lower priority, but only once, using idle watchers to keep the event	1498	of lower priority, but only once, using idle watchers to keep the event
1138	loop from blocking if lower-priority coroutines are active, thus mapping	1499	loop from blocking if lower-priority coroutines are active, thus mapping
1139	low-priority coroutines to idle/background tasks).	1500	low-priority coroutines to idle/background tasks).
1140		1501
		1502	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1503	priority, to ensure that they are being run before any other watchers
		1504	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1505	too) should not activate ("feed") events into libev. While libev fully
		1506	supports this, they will be called before other C<ev_check> watchers did
		1507	their job. As C<ev_check> watchers are often used to embed other event
		1508	loops those other event loops might be in an unusable state until their
		1509	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1510	others).
		1511
1141	=over 4	1512	=over 4
1142		1513
1143	=item ev_prepare_init (ev_prepare *, callback)	1514	=item ev_prepare_init (ev_prepare *, callback)
1144		1515
1145	=item ev_check_init (ev_check *, callback)	1516	=item ev_check_init (ev_check *, callback)
…		…
1148	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1519	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1149	macros, but using them is utterly, utterly and completely pointless.	1520	macros, but using them is utterly, utterly and completely pointless.
1150		1521
1151	=back	1522	=back
1152		1523
1153	Example: To include a library such as adns, you would add IO watchers	1524	There are a number of principal ways to embed other event loops or modules
1154	and a timeout watcher in a prepare handler, as required by libadns, and	1525	into libev. Here are some ideas on how to include libadns into libev
		1526	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1527	use for an actually working example. Another Perl module named C<EV::Glib>
		1528	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1529	into the Glib event loop).
		1530
		1531	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1155	in a check watcher, destroy them and call into libadns. What follows is	1532	and in a check watcher, destroy them and call into libadns. What follows
1156	pseudo-code only of course:	1533	is pseudo-code only of course. This requires you to either use a low
		1534	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1535	the callbacks for the IO/timeout watchers might not have been called yet.
1157		1536
1158	static ev_io iow [nfd];	1537	static ev_io iow [nfd];
1159	static ev_timer tw;	1538	static ev_timer tw;
1160		1539
1161	static void	1540	static void
1162	io_cb (ev_loop loop, ev_io w, int revents)	1541	io_cb (ev_loop loop, ev_io w, int revents)
1163	{	1542	{
1164	// set the relevant poll flags
1165	// could also call adns_processreadable etc. here
1166	struct pollfd fd = (struct pollfd )w->data;
1167	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1168	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1169	}	1543	}
1170		1544
1171	// create io watchers for each fd and a timer before blocking	1545	// create io watchers for each fd and a timer before blocking
1172	static void	1546	static void
1173	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1547	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1174	{	1548	{
1175	int timeout = 3600000;truct pollfd fds [nfd];	1549	int timeout = 3600000;
		1550	struct pollfd fds [nfd];
1176	// actual code will need to loop here and realloc etc.	1551	// actual code will need to loop here and realloc etc.
1177	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1552	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1178		1553
1179	/* the callback is illegal, but won't be called as we stop during check */	1554	/* the callback is illegal, but won't be called as we stop during check */
1180	ev_timer_init (&tw, 0, timeout * 1e-3);	1555	ev_timer_init (&tw, 0, timeout * 1e-3);
1181	ev_timer_start (loop, &tw);	1556	ev_timer_start (loop, &tw);
1182		1557
1183	// create on ev_io per pollfd	1558	// create one ev_io per pollfd
1184	for (int i = 0; i < nfd; ++i)	1559	for (int i = 0; i < nfd; ++i)
1185	{	1560	{
1186	ev_io_init (iow + i, io_cb, fds [i].fd,	1561	ev_io_init (iow + i, io_cb, fds [i].fd,
1187	((fds [i].events & POLLIN ? EV_READ : 0)	1562	((fds [i].events & POLLIN ? EV_READ : 0)
1188	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1563	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1189		1564
1190	fds [i].revents = 0;	1565	fds [i].revents = 0;
1191	iow [i].data = fds + i;
1192	ev_io_start (loop, iow + i);	1566	ev_io_start (loop, iow + i);
1193	}	1567	}
1194	}	1568	}
1195		1569
1196	// stop all watchers after blocking	1570	// stop all watchers after blocking
…		…
1198	adns_check_cb (ev_loop loop, ev_check w, int revents)	1572	adns_check_cb (ev_loop loop, ev_check w, int revents)
1199	{	1573	{
1200	ev_timer_stop (loop, &tw);	1574	ev_timer_stop (loop, &tw);
1201		1575
1202	for (int i = 0; i < nfd; ++i)	1576	for (int i = 0; i < nfd; ++i)
		1577	{
		1578	// set the relevant poll flags
		1579	// could also call adns_processreadable etc. here
		1580	struct pollfd *fd = fds + i;
		1581	int revents = ev_clear_pending (iow + i);
		1582	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1583	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1584
		1585	// now stop the watcher
1203	ev_io_stop (loop, iow + i);	1586	ev_io_stop (loop, iow + i);
		1587	}
1204		1588
1205	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1589	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1590	}
		1591
		1592	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1593	in the prepare watcher and would dispose of the check watcher.
		1594
		1595	Method 3: If the module to be embedded supports explicit event
		1596	notification (adns does), you can also make use of the actual watcher
		1597	callbacks, and only destroy/create the watchers in the prepare watcher.
		1598
		1599	static void
		1600	timer_cb (EV_P_ ev_timer *w, int revents)
		1601	{
		1602	adns_state ads = (adns_state)w->data;
		1603	update_now (EV_A);
		1604
		1605	adns_processtimeouts (ads, &tv_now);
		1606	}
		1607
		1608	static void
		1609	io_cb (EV_P_ ev_io *w, int revents)
		1610	{
		1611	adns_state ads = (adns_state)w->data;
		1612	update_now (EV_A);
		1613
		1614	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1615	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1616	}
		1617
		1618	// do not ever call adns_afterpoll
		1619
		1620	Method 4: Do not use a prepare or check watcher because the module you
		1621	want to embed is too inflexible to support it. Instead, youc na override
		1622	their poll function. The drawback with this solution is that the main
		1623	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1624	this.
		1625
		1626	static gint
		1627	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1628	{
		1629	int got_events = 0;
		1630
		1631	for (n = 0; n < nfds; ++n)
		1632	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1633
		1634	if (timeout >= 0)
		1635	// create/start timer
		1636
		1637	// poll
		1638	ev_loop (EV_A_ 0);
		1639
		1640	// stop timer again
		1641	if (timeout >= 0)
		1642	ev_timer_stop (EV_A_ &to);
		1643
		1644	// stop io watchers again - their callbacks should have set
		1645	for (n = 0; n < nfds; ++n)
		1646	ev_io_stop (EV_A_ iow [n]);
		1647
		1648	return got_events;
1206	}	1649	}
1207		1650
1208		1651
1209	=head2 C<ev_embed> - when one backend isn't enough...	1652	=head2 C<ev_embed> - when one backend isn't enough...
1210		1653
…		…
1292		1735
1293	Make a single, non-blocking sweep over the embedded loop. This works	1736	Make a single, non-blocking sweep over the embedded loop. This works
1294	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1737	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1295	apropriate way for embedded loops.	1738	apropriate way for embedded loops.
1296		1739
		1740	=item struct ev_loop *loop [read-only]
		1741
		1742	The embedded event loop.
		1743
		1744	=back
		1745
		1746
		1747	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1748
		1749	Fork watchers are called when a C<fork ()> was detected (usually because
		1750	whoever is a good citizen cared to tell libev about it by calling
		1751	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1752	event loop blocks next and before C<ev_check> watchers are being called,
		1753	and only in the child after the fork. If whoever good citizen calling
		1754	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1755	handlers will be invoked, too, of course.
		1756
		1757	=over 4
		1758
		1759	=item ev_fork_init (ev_signal *, callback)
		1760
		1761	Initialises and configures the fork watcher - it has no parameters of any
		1762	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1763	believe me.
		1764
1297	=back	1765	=back
1298		1766
1299		1767
1300	=head1 OTHER FUNCTIONS	1768	=head1 OTHER FUNCTIONS
1301		1769
…		…
1389		1857
1390	To use it,	1858	To use it,
1391		1859
1392	#include <ev++.h>	1860	#include <ev++.h>
1393		1861
1394	(it is not installed by default). This automatically includes F<ev.h>	1862	This automatically includes F<ev.h> and puts all of its definitions (many
1395	and puts all of its definitions (many of them macros) into the global	1863	of them macros) into the global namespace. All C++ specific things are
1396	namespace. All C++ specific things are put into the C<ev> namespace.	1864	put into the C<ev> namespace. It should support all the same embedding
		1865	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1397		1866
1398	It should support all the same embedding options as F<ev.h>, most notably	1867	Care has been taken to keep the overhead low. The only data member the C++
1399	C<EV_MULTIPLICITY>.	1868	classes add (compared to plain C-style watchers) is the event loop pointer
		1869	that the watcher is associated with (or no additional members at all if
		1870	you disable C<EV_MULTIPLICITY> when embedding libev).
		1871
		1872	Currently, functions, and static and non-static member functions can be
		1873	used as callbacks. Other types should be easy to add as long as they only
		1874	need one additional pointer for context. If you need support for other
		1875	types of functors please contact the author (preferably after implementing
		1876	it).
1400		1877
1401	Here is a list of things available in the C<ev> namespace:	1878	Here is a list of things available in the C<ev> namespace:
1402		1879
1403	=over 4	1880	=over 4
1404		1881
…		…
1420		1897
1421	All of those classes have these methods:	1898	All of those classes have these methods:
1422		1899
1423	=over 4	1900	=over 4
1424		1901
1425	=item ev::TYPE::TYPE (object , object::method )	1902	=item ev::TYPE::TYPE ()
1426		1903
1427	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1904	=item ev::TYPE::TYPE (struct ev_loop *)
1428		1905
1429	=item ev::TYPE::~TYPE	1906	=item ev::TYPE::~TYPE
1430		1907
1431	The constructor takes a pointer to an object and a method pointer to	1908	The constructor (optionally) takes an event loop to associate the watcher
1432	the event handler callback to call in this class. The constructor calls	1909	with. If it is omitted, it will use C<EV_DEFAULT>.
1433	C<ev_init> for you, which means you have to call the C<set> method	1910
1434	before starting it. If you do not specify a loop then the constructor	1911	The constructor calls C<ev_init> for you, which means you have to call the
1435	automatically associates the default loop with this watcher.	1912	C<set> method before starting it.
		1913
		1914	It will not set a callback, however: You have to call the templated C<set>
		1915	method to set a callback before you can start the watcher.
		1916
		1917	(The reason why you have to use a method is a limitation in C++ which does
		1918	not allow explicit template arguments for constructors).
1436		1919
1437	The destructor automatically stops the watcher if it is active.	1920	The destructor automatically stops the watcher if it is active.
		1921
		1922	=item w->set<class, &class::method> (object *)
		1923
		1924	This method sets the callback method to call. The method has to have a
		1925	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1926	first argument and the C<revents> as second. The object must be given as
		1927	parameter and is stored in the C<data> member of the watcher.
		1928
		1929	This method synthesizes efficient thunking code to call your method from
		1930	the C callback that libev requires. If your compiler can inline your
		1931	callback (i.e. it is visible to it at the place of the C<set> call and
		1932	your compiler is good :), then the method will be fully inlined into the
		1933	thunking function, making it as fast as a direct C callback.
		1934
		1935	Example: simple class declaration and watcher initialisation
		1936
		1937	struct myclass
		1938	{
		1939	void io_cb (ev::io &w, int revents) { }
		1940	}
		1941
		1942	myclass obj;
		1943	ev::io iow;
		1944	iow.set <myclass, &myclass::io_cb> (&obj);
		1945
		1946	=item w->set<function> (void *data = 0)
		1947
		1948	Also sets a callback, but uses a static method or plain function as
		1949	callback. The optional C<data> argument will be stored in the watcher's
		1950	C<data> member and is free for you to use.
		1951
		1952	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		1953
		1954	See the method-C<set> above for more details.
		1955
		1956	Example:
		1957
		1958	static void io_cb (ev::io &w, int revents) { }
		1959	iow.set <io_cb> ();
1438		1960
1439	=item w->set (struct ev_loop *)	1961	=item w->set (struct ev_loop *)
1440		1962
1441	Associates a different C<struct ev_loop> with this watcher. You can only	1963	Associates a different C<struct ev_loop> with this watcher. You can only
1442	do this when the watcher is inactive (and not pending either).	1964	do this when the watcher is inactive (and not pending either).
1443		1965
1444	=item w->set ([args])	1966	=item w->set ([args])
1445		1967
1446	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1968	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1447	called at least once. Unlike the C counterpart, an active watcher gets	1969	called at least once. Unlike the C counterpart, an active watcher gets
1448	automatically stopped and restarted.	1970	automatically stopped and restarted when reconfiguring it with this
		1971	method.
1449		1972
1450	=item w->start ()	1973	=item w->start ()
1451		1974
1452	Starts the watcher. Note that there is no C<loop> argument as the	1975	Starts the watcher. Note that there is no C<loop> argument, as the
1453	constructor already takes the loop.	1976	constructor already stores the event loop.
1454		1977
1455	=item w->stop ()	1978	=item w->stop ()
1456		1979
1457	Stops the watcher if it is active. Again, no C<loop> argument.	1980	Stops the watcher if it is active. Again, no C<loop> argument.
1458		1981
…		…
1463		1986
1464	=item w->sweep () C<ev::embed> only	1987	=item w->sweep () C<ev::embed> only
1465		1988
1466	Invokes C<ev_embed_sweep>.	1989	Invokes C<ev_embed_sweep>.
1467		1990
		1991	=item w->update () C<ev::stat> only
		1992
		1993	Invokes C<ev_stat_stat>.
		1994
1468	=back	1995	=back
1469		1996
1470	=back	1997	=back
1471		1998
1472	Example: Define a class with an IO and idle watcher, start one of them in	1999	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1479		2006
1480	myclass ();	2007	myclass ();
1481	}	2008	}
1482		2009
1483	myclass::myclass (int fd)	2010	myclass::myclass (int fd)
1484	: io (this, &myclass::io_cb),
1485	idle (this, &myclass::idle_cb)
1486	{	2011	{
		2012	io .set <myclass, &myclass::io_cb > (this);
		2013	idle.set <myclass, &myclass::idle_cb> (this);
		2014
1487	io.start (fd, ev::READ);	2015	io.start (fd, ev::READ);
1488	}	2016	}
		2017
		2018
		2019	=head1 MACRO MAGIC
		2020
		2021	Libev can be compiled with a variety of options, the most fundemantal is
		2022	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
		2023	callbacks have an initial C<struct ev_loop *> argument.
		2024
		2025	To make it easier to write programs that cope with either variant, the
		2026	following macros are defined:
		2027
		2028	=over 4
		2029
		2030	=item C<EV_A>, C<EV_A_>
		2031
		2032	This provides the loop I<argument> for functions, if one is required ("ev
		2033	loop argument"). The C<EV_A> form is used when this is the sole argument,
		2034	C<EV_A_> is used when other arguments are following. Example:
		2035
		2036	ev_unref (EV_A);
		2037	ev_timer_add (EV_A_ watcher);
		2038	ev_loop (EV_A_ 0);
		2039
		2040	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		2041	which is often provided by the following macro.
		2042
		2043	=item C<EV_P>, C<EV_P_>
		2044
		2045	This provides the loop I<parameter> for functions, if one is required ("ev
		2046	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		2047	C<EV_P_> is used when other parameters are following. Example:
		2048
		2049	// this is how ev_unref is being declared
		2050	static void ev_unref (EV_P);
		2051
		2052	// this is how you can declare your typical callback
		2053	static void cb (EV_P_ ev_timer *w, int revents)
		2054
		2055	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		2056	suitable for use with C<EV_A>.
		2057
		2058	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		2059
		2060	Similar to the other two macros, this gives you the value of the default
		2061	loop, if multiple loops are supported ("ev loop default").
		2062
		2063	=back
		2064
		2065	Example: Declare and initialise a check watcher, utilising the above
		2066	macros so it will work regardless of whether multiple loops are supported
		2067	or not.
		2068
		2069	static void
		2070	check_cb (EV_P_ ev_timer *w, int revents)
		2071	{
		2072	ev_check_stop (EV_A_ w);
		2073	}
		2074
		2075	ev_check check;
		2076	ev_check_init (&check, check_cb);
		2077	ev_check_start (EV_DEFAULT_ &check);
		2078	ev_loop (EV_DEFAULT_ 0);
1489		2079
1490	=head1 EMBEDDING	2080	=head1 EMBEDDING
1491		2081
1492	Libev can (and often is) directly embedded into host	2082	Libev can (and often is) directly embedded into host
1493	applications. Examples of applications that embed it include the Deliantra	2083	applications. Examples of applications that embed it include the Deliantra
…		…
1533	ev_vars.h	2123	ev_vars.h
1534	ev_wrap.h	2124	ev_wrap.h
1535		2125
1536	ev_win32.c required on win32 platforms only	2126	ev_win32.c required on win32 platforms only
1537		2127
1538	ev_select.c only when select backend is enabled (which is by default)	2128	ev_select.c only when select backend is enabled (which is enabled by default)
1539	ev_poll.c only when poll backend is enabled (disabled by default)	2129	ev_poll.c only when poll backend is enabled (disabled by default)
1540	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2130	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1541	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2131	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1542	ev_port.c only when the solaris port backend is enabled (disabled by default)	2132	ev_port.c only when the solaris port backend is enabled (disabled by default)
1543		2133
…		…
1668		2258
1669	=item EV_USE_DEVPOLL	2259	=item EV_USE_DEVPOLL
1670		2260
1671	reserved for future expansion, works like the USE symbols above.	2261	reserved for future expansion, works like the USE symbols above.
1672		2262
		2263	=item EV_USE_INOTIFY
		2264
		2265	If defined to be C<1>, libev will compile in support for the Linux inotify
		2266	interface to speed up C<ev_stat> watchers. Its actual availability will
		2267	be detected at runtime.
		2268
1673	=item EV_H	2269	=item EV_H
1674		2270
1675	The name of the F<ev.h> header file used to include it. The default if	2271	The name of the F<ev.h> header file used to include it. The default if
1676	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2272	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1677	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2273	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
1700	will have the C<struct ev_loop *> as first argument, and you can create	2296	will have the C<struct ev_loop *> as first argument, and you can create
1701	additional independent event loops. Otherwise there will be no support	2297	additional independent event loops. Otherwise there will be no support
1702	for multiple event loops and there is no first event loop pointer	2298	for multiple event loops and there is no first event loop pointer
1703	argument. Instead, all functions act on the single default loop.	2299	argument. Instead, all functions act on the single default loop.
1704		2300
		2301	=item EV_MINPRI
		2302
		2303	=item EV_MAXPRI
		2304
		2305	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2306	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2307	provide for more priorities by overriding those symbols (usually defined
		2308	to be C<-2> and C<2>, respectively).
		2309
		2310	When doing priority-based operations, libev usually has to linearly search
		2311	all the priorities, so having many of them (hundreds) uses a lot of space
		2312	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2313	fine.
		2314
		2315	If your embedding app does not need any priorities, defining these both to
		2316	C<0> will save some memory and cpu.
		2317
1705	=item EV_PERIODICS	2318	=item EV_PERIODIC_ENABLE
1706		2319
1707	If undefined or defined to be C<1>, then periodic timers are supported,	2320	If undefined or defined to be C<1>, then periodic timers are supported. If
1708	otherwise not. This saves a few kb of code.	2321	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2322	code.
		2323
		2324	=item EV_IDLE_ENABLE
		2325
		2326	If undefined or defined to be C<1>, then idle watchers are supported. If
		2327	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2328	code.
		2329
		2330	=item EV_EMBED_ENABLE
		2331
		2332	If undefined or defined to be C<1>, then embed watchers are supported. If
		2333	defined to be C<0>, then they are not.
		2334
		2335	=item EV_STAT_ENABLE
		2336
		2337	If undefined or defined to be C<1>, then stat watchers are supported. If
		2338	defined to be C<0>, then they are not.
		2339
		2340	=item EV_FORK_ENABLE
		2341
		2342	If undefined or defined to be C<1>, then fork watchers are supported. If
		2343	defined to be C<0>, then they are not.
		2344
		2345	=item EV_MINIMAL
		2346
		2347	If you need to shave off some kilobytes of code at the expense of some
		2348	speed, define this symbol to C<1>. Currently only used for gcc to override
		2349	some inlining decisions, saves roughly 30% codesize of amd64.
		2350
		2351	=item EV_PID_HASHSIZE
		2352
		2353	C<ev_child> watchers use a small hash table to distribute workload by
		2354	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2355	than enough. If you need to manage thousands of children you might want to
		2356	increase this value (I<must> be a power of two).
		2357
		2358	=item EV_INOTIFY_HASHSIZE
		2359
		2360	C<ev_staz> watchers use a small hash table to distribute workload by
		2361	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2362	usually more than enough. If you need to manage thousands of C<ev_stat>
		2363	watchers you might want to increase this value (I<must> be a power of
		2364	two).
1709		2365
1710	=item EV_COMMON	2366	=item EV_COMMON
1711		2367
1712	By default, all watchers have a C<void *data> member. By redefining	2368	By default, all watchers have a C<void *data> member. By redefining
1713	this macro to a something else you can include more and other types of	2369	this macro to a something else you can include more and other types of
…		…
1742	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2398	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
1743	will be compiled. It is pretty complex because it provides its own header	2399	will be compiled. It is pretty complex because it provides its own header
1744	file.	2400	file.
1745		2401
1746	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2402	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
1747	that everybody includes and which overrides some autoconf choices:	2403	that everybody includes and which overrides some configure choices:
1748		2404
		2405	#define EV_MINIMAL 1
1749	#define EV_USE_POLL 0	2406	#define EV_USE_POLL 0
1750	#define EV_MULTIPLICITY 0	2407	#define EV_MULTIPLICITY 0
1751	#define EV_PERIODICS 0	2408	#define EV_PERIODIC_ENABLE 0
		2409	#define EV_STAT_ENABLE 0
		2410	#define EV_FORK_ENABLE 0
1752	#define EV_CONFIG_H <config.h>	2411	#define EV_CONFIG_H <config.h>
		2412	#define EV_MINPRI 0
		2413	#define EV_MAXPRI 0
1753		2414
1754	#include "ev++.h"	2415	#include "ev++.h"
1755		2416
1756	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2417	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1757		2418
…		…
1763		2424
1764	In this section the complexities of (many of) the algorithms used inside	2425	In this section the complexities of (many of) the algorithms used inside
1765	libev will be explained. For complexity discussions about backends see the	2426	libev will be explained. For complexity discussions about backends see the
1766	documentation for C<ev_default_init>.	2427	documentation for C<ev_default_init>.
1767		2428
		2429	All of the following are about amortised time: If an array needs to be
		2430	extended, libev needs to realloc and move the whole array, but this
		2431	happens asymptotically never with higher number of elements, so O(1) might
		2432	mean it might do a lengthy realloc operation in rare cases, but on average
		2433	it is much faster and asymptotically approaches constant time.
		2434
1768	=over 4	2435	=over 4
1769		2436
1770	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2437	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
1771		2438
		2439	This means that, when you have a watcher that triggers in one hour and
		2440	there are 100 watchers that would trigger before that then inserting will
		2441	have to skip those 100 watchers.
		2442
1772	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2443	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
1773		2444
		2445	That means that for changing a timer costs less than removing/adding them
		2446	as only the relative motion in the event queue has to be paid for.
		2447
1774	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2448	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
1775		2449
		2450	These just add the watcher into an array or at the head of a list.
1776	=item Stopping check/prepare/idle watchers: O(1)	2451	=item Stopping check/prepare/idle watchers: O(1)
1777		2452
1778	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2453	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2454
		2455	These watchers are stored in lists then need to be walked to find the
		2456	correct watcher to remove. The lists are usually short (you don't usually
		2457	have many watchers waiting for the same fd or signal).
1779		2458
1780	=item Finding the next timer per loop iteration: O(1)	2459	=item Finding the next timer per loop iteration: O(1)
1781		2460
1782	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2461	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
1783		2462
		2463	A change means an I/O watcher gets started or stopped, which requires
		2464	libev to recalculate its status (and possibly tell the kernel).
		2465
1784	=item Activating one watcher: O(1)	2466	=item Activating one watcher: O(1)
1785		2467
		2468	=item Priority handling: O(number_of_priorities)
		2469
		2470	Priorities are implemented by allocating some space for each
		2471	priority. When doing priority-based operations, libev usually has to
		2472	linearly search all the priorities.
		2473
1786	=back	2474	=back
1787		2475
1788		2476
1789	=head1 AUTHOR	2477	=head1 AUTHOR
1790		2478

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Comparing libev/ev.pod (file contents): Revision 1.46 by root, Mon Nov 26 10:20:43 2007 UTC vs. Revision 1.80 by root, Sun Dec 9 19:47:30 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.46 by root, Mon Nov 26 10:20:43 2007 UTC vs.
Revision 1.80 by root, Sun Dec 9 19:47:30 2007 UTC