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…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head1 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
11	#include <ev.h>	11	#include <ev.h>
12		12
13	ev_io stdin_watcher;	13	ev_io stdin_watcher;
14	ev_timer timeout_watcher;	14	ev_timer timeout_watcher;
…		…
48	return 0;	48	return 0;
49	}	49	}
50		50
51	=head1 DESCRIPTION	51	=head1 DESCRIPTION
52		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>.
		56
53	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
54	file descriptor being readable or a timeout occuring), and it will manage	58	file descriptor being readable or a timeout occurring), and it will manage
55	these event sources and provide your program with events.	59	these event sources and provide your program with events.
56		60
57	To do this, it must take more or less complete control over your process	61	To do this, it must take more or less complete control over your process
58	(or thread) by executing the I<event loop> handler, and will then	62	(or thread) by executing the I<event loop> handler, and will then
59	communicate events via a callback mechanism.	63	communicate events via a callback mechanism.
…		…
61	You register interest in certain events by registering so-called I<event	65	You register interest in certain events by registering so-called I<event
62	watchers>, which are relatively small C structures you initialise with the	66	watchers>, which are relatively small C structures you initialise with the
63	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
64	watcher.	68	watcher.
65		69
66	=head1 FEATURES	70	=head2 FEATURES
67		71
68	Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the	72	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
69	bsd-specific C<kqueue> and the solaris-specific event port mechanisms	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
70	for file descriptor events (C<ev_io>), relative timers (C<ev_timer>),	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
		75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
71	absolute timers with customised rescheduling (C<ev_periodic>), synchronous	76	with customised rescheduling (C<ev_periodic>), synchronous signals
72	signals (C<ev_signal>), process status change events (C<ev_child>), and	77	(C<ev_signal>), process status change events (C<ev_child>), and event
73	event watchers dealing with the event loop mechanism itself (C<ev_idle>,	78	watchers dealing with the event loop mechanism itself (C<ev_idle>,
74	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as	79	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
75	file watchers (C<ev_stat>) and even limited support for fork events	80	file watchers (C<ev_stat>) and even limited support for fork events
76	(C<ev_fork>).	81	(C<ev_fork>).
77		82
78	It also is quite fast (see this	83	It also is quite fast (see this
79	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent	84	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
80	for example).	85	for example).
81		86
82	=head1 CONVENTIONS	87	=head2 CONVENTIONS
83		88
84	Libev is very configurable. In this manual the default configuration will	89	Libev is very configurable. In this manual the default configuration will
85	be described, which supports multiple event loops. For more info about	90	be described, which supports multiple event loops. For more info about
86	various configuration options please have a look at B<EMBED> section in	91	various configuration options please have a look at B<EMBED> section in
87	this manual. If libev was configured without support for multiple event	92	this manual. If libev was configured without support for multiple event
88	loops, then all functions taking an initial argument of name C<loop>	93	loops, then all functions taking an initial argument of name C<loop>
89	(which is always of type C<struct ev_loop *>) will not have this argument.	94	(which is always of type C<struct ev_loop *>) will not have this argument.
90		95
91	=head1 TIME REPRESENTATION	96	=head2 TIME REPRESENTATION
92		97
93	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
94	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
95	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
96	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
97	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
98	it, you should treat it as such.	103	it, you should treat it as some floatingpoint value. Unlike the name
		104	component C<stamp> might indicate, it is also used for time differences
		105	throughout libev.
99		106
100	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
101		108
102	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
103	library in any way.	110	library in any way.
…		…
108		115
109	Returns the current time as libev would use it. Please note that the	116	Returns the current time as libev would use it. Please note that the
110	C<ev_now> function is usually faster and also often returns the timestamp	117	C<ev_now> function is usually faster and also often returns the timestamp
111	you actually want to know.	118	you actually want to know.
112		119
		120	=item ev_sleep (ev_tstamp interval)
		121
		122	Sleep for the given interval: The current thread will be blocked until
		123	either it is interrupted or the given time interval has passed. Basically
		124	this is a subsecond-resolution C<sleep ()>.
		125
113	=item int ev_version_major ()	126	=item int ev_version_major ()
114		127
115	=item int ev_version_minor ()	128	=item int ev_version_minor ()
116		129
117	You can find out the major and minor version numbers of the library	130	You can find out the major and minor ABI version numbers of the library
118	you linked against by calling the functions C<ev_version_major> and	131	you linked against by calling the functions C<ev_version_major> and
119	C<ev_version_minor>. If you want, you can compare against the global	132	C<ev_version_minor>. If you want, you can compare against the global
120	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	133	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
121	version of the library your program was compiled against.	134	version of the library your program was compiled against.
122		135
		136	These version numbers refer to the ABI version of the library, not the
		137	release version.
		138
123	Usually, it's a good idea to terminate if the major versions mismatch,	139	Usually, it's a good idea to terminate if the major versions mismatch,
124	as this indicates an incompatible change. Minor versions are usually	140	as this indicates an incompatible change. Minor versions are usually
125	compatible to older versions, so a larger minor version alone is usually	141	compatible to older versions, so a larger minor version alone is usually
126	not a problem.	142	not a problem.
127		143
128	Example: Make sure we haven't accidentally been linked against the wrong	144	Example: Make sure we haven't accidentally been linked against the wrong
129	version.	145	version.
…		…
162	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	178	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
163	recommended ones.	179	recommended ones.
164		180
165	See the description of C<ev_embed> watchers for more info.	181	See the description of C<ev_embed> watchers for more info.
166		182
167	=item ev_set_allocator (void *(*cb)(void *ptr, size_t size))	183	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
168		184
169	Sets the allocation function to use (the prototype and semantics are	185	Sets the allocation function to use (the prototype is similar - the
170	identical to the realloc C function). It is used to allocate and free	186	semantics is identical - to the realloc C function). It is used to
171	memory (no surprises here). If it returns zero when memory needs to be	187	allocate and free memory (no surprises here). If it returns zero when
172	allocated, the library might abort or take some potentially destructive	188	memory needs to be allocated, the library might abort or take some
173	action. The default is your system realloc function.	189	potentially destructive action. The default is your system realloc
		190	function.
174		191
175	You could override this function in high-availability programs to, say,	192	You could override this function in high-availability programs to, say,
176	free some memory if it cannot allocate memory, to use a special allocator,	193	free some memory if it cannot allocate memory, to use a special allocator,
177	or even to sleep a while and retry until some memory is available.	194	or even to sleep a while and retry until some memory is available.
178		195
…		…
243	flags. If that is troubling you, check C<ev_backend ()> afterwards).	260	flags. If that is troubling you, check C<ev_backend ()> afterwards).
244		261
245	If you don't know what event loop to use, use the one returned from this	262	If you don't know what event loop to use, use the one returned from this
246	function.	263	function.
247		264
		265	The default loop is the only loop that can handle C<ev_signal> and
		266	C<ev_child> watchers, and to do this, it always registers a handler
		267	for C<SIGCHLD>. If this is a problem for your app you can either
		268	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
		269	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
		270	C<ev_default_init>.
		271
248	The flags argument can be used to specify special behaviour or specific	272	The flags argument can be used to specify special behaviour or specific
249	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	273	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
250		274
251	The following flags are supported:	275	The following flags are supported:
252		276
…		…
264	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	288	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
265	override the flags completely if it is found in the environment. This is	289	override the flags completely if it is found in the environment. This is
266	useful to try out specific backends to test their performance, or to work	290	useful to try out specific backends to test their performance, or to work
267	around bugs.	291	around bugs.
268		292
		293	=item C<EVFLAG_FORKCHECK>
		294
		295	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		296	a fork, you can also make libev check for a fork in each iteration by
		297	enabling this flag.
		298
		299	This works by calling C<getpid ()> on every iteration of the loop,
		300	and thus this might slow down your event loop if you do a lot of loop
		301	iterations and little real work, but is usually not noticeable (on my
		302	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		303	without a syscall and thus I<very> fast, but my Linux system also has
		304	C<pthread_atfork> which is even faster).
		305
		306	The big advantage of this flag is that you can forget about fork (and
		307	forget about forgetting to tell libev about forking) when you use this
		308	flag.
		309
		310	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		311	environment variable.
		312
269	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	313	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
270		314
271	This is your standard select(2) backend. Not I<completely> standard, as	315	This is your standard select(2) backend. Not I<completely> standard, as
272	libev tries to roll its own fd_set with no limits on the number of fds,	316	libev tries to roll its own fd_set with no limits on the number of fds,
273	but if that fails, expect a fairly low limit on the number of fds when	317	but if that fails, expect a fairly low limit on the number of fds when
274	using this backend. It doesn't scale too well (O(highest_fd)), but its usually	318	using this backend. It doesn't scale too well (O(highest_fd)), but its
275	the fastest backend for a low number of fds.	319	usually the fastest backend for a low number of (low-numbered :) fds.
		320
		321	To get good performance out of this backend you need a high amount of
		322	parallelity (most of the file descriptors should be busy). If you are
		323	writing a server, you should C<accept ()> in a loop to accept as many
		324	connections as possible during one iteration. You might also want to have
		325	a look at C<ev_set_io_collect_interval ()> to increase the amount of
		326	readyness notifications you get per iteration.
276		327
277	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	328	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
278		329
279	And this is your standard poll(2) backend. It's more complicated than	330	And this is your standard poll(2) backend. It's more complicated
280	select, but handles sparse fds better and has no artificial limit on the	331	than select, but handles sparse fds better and has no artificial
281	number of fds you can use (except it will slow down considerably with a	332	limit on the number of fds you can use (except it will slow down
282	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).	333	considerably with a lot of inactive fds). It scales similarly to select,
		334	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for
		335	performance tips.
283		336
284	=item C<EVBACKEND_EPOLL> (value 4, Linux)	337	=item C<EVBACKEND_EPOLL> (value 4, Linux)
285		338
286	For few fds, this backend is a bit little slower than poll and select,	339	For few fds, this backend is a bit little slower than poll and select,
287	but it scales phenomenally better. While poll and select usually scale like	340	but it scales phenomenally better. While poll and select usually scale
288	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales	341	like O(total_fds) where n is the total number of fds (or the highest fd),
289	either O(1) or O(active_fds).	342	epoll scales either O(1) or O(active_fds). The epoll design has a number
		343	of shortcomings, such as silently dropping events in some hard-to-detect
		344	cases and rewiring a syscall per fd change, no fork support and bad
		345	support for dup.
290		346
291	While stopping and starting an I/O watcher in the same iteration will	347	While stopping, setting and starting an I/O watcher in the same iteration
292	result in some caching, there is still a syscall per such incident	348	will result in some caching, there is still a syscall per such incident
293	(because the fd could point to a different file description now), so its	349	(because the fd could point to a different file description now), so its
294	best to avoid that. Also, dup()ed file descriptors might not work very	350	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
295	well if you register events for both fds.	351	very well if you register events for both fds.
296		352
297	Please note that epoll sometimes generates spurious notifications, so you	353	Please note that epoll sometimes generates spurious notifications, so you
298	need to use non-blocking I/O or other means to avoid blocking when no data	354	need to use non-blocking I/O or other means to avoid blocking when no data
299	(or space) is available.	355	(or space) is available.
300		356
		357	Best performance from this backend is achieved by not unregistering all
		358	watchers for a file descriptor until it has been closed, if possible, i.e.
		359	keep at least one watcher active per fd at all times.
		360
		361	While nominally embeddeble in other event loops, this feature is broken in
		362	all kernel versions tested so far.
		363
301	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	364	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
302		365
303	Kqueue deserves special mention, as at the time of this writing, it	366	Kqueue deserves special mention, as at the time of this writing, it
304	was broken on all BSDs except NetBSD (usually it doesn't work with	367	was broken on all BSDs except NetBSD (usually it doesn't work reliably
305	anything but sockets and pipes, except on Darwin, where of course its	368	with anything but sockets and pipes, except on Darwin, where of course
306	completely useless). For this reason its not being "autodetected"	369	it's completely useless). For this reason it's not being "autodetected"
307	unless you explicitly specify it explicitly in the flags (i.e. using	370	unless you explicitly specify it explicitly in the flags (i.e. using
308	C<EVBACKEND_KQUEUE>).	371	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
		372	system like NetBSD.
		373
		374	You still can embed kqueue into a normal poll or select backend and use it
		375	only for sockets (after having made sure that sockets work with kqueue on
		376	the target platform). See C<ev_embed> watchers for more info.
309		377
310	It scales in the same way as the epoll backend, but the interface to the	378	It scales in the same way as the epoll backend, but the interface to the
311	kernel is more efficient (which says nothing about its actual speed, of	379	kernel is more efficient (which says nothing about its actual speed, of
312	course). While starting and stopping an I/O watcher does not cause an	380	course). While stopping, setting and starting an I/O watcher does never
313	extra syscall as with epoll, it still adds up to four event changes per	381	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to
314	incident, so its best to avoid that.	382	two event changes per incident, support for C<fork ()> is very bad and it
		383	drops fds silently in similarly hard-to-detect cases.
		384
		385	This backend usually performs well under most conditions.
		386
		387	While nominally embeddable in other event loops, this doesn't work
		388	everywhere, so you might need to test for this. And since it is broken
		389	almost everywhere, you should only use it when you have a lot of sockets
		390	(for which it usually works), by embedding it into another event loop
		391	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for
		392	sockets.
315		393
316	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	394	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
317		395
318	This is not implemented yet (and might never be).	396	This is not implemented yet (and might never be, unless you send me an
		397	implementation). According to reports, C</dev/poll> only supports sockets
		398	and is not embeddable, which would limit the usefulness of this backend
		399	immensely.
319		400
320	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	401	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
321		402
322	This uses the Solaris 10 port mechanism. As with everything on Solaris,	403	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
323	it's really slow, but it still scales very well (O(active_fds)).	404	it's really slow, but it still scales very well (O(active_fds)).
324		405
325	Please note that solaris ports can result in a lot of spurious	406	Please note that solaris event ports can deliver a lot of spurious
326	notifications, so you need to use non-blocking I/O or other means to avoid	407	notifications, so you need to use non-blocking I/O or other means to avoid
327	blocking when no data (or space) is available.	408	blocking when no data (or space) is available.
		409
		410	While this backend scales well, it requires one system call per active
		411	file descriptor per loop iteration. For small and medium numbers of file
		412	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
		413	might perform better.
		414
		415	On the positive side, ignoring the spurious readyness notifications, this
		416	backend actually performed to specification in all tests and is fully
		417	embeddable, which is a rare feat among the OS-specific backends.
328		418
329	=item C<EVBACKEND_ALL>	419	=item C<EVBACKEND_ALL>
330		420
331	Try all backends (even potentially broken ones that wouldn't be tried	421	Try all backends (even potentially broken ones that wouldn't be tried
332	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	422	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
333	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	423	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
334		424
		425	It is definitely not recommended to use this flag.
		426
335	=back	427	=back
336		428
337	If one or more of these are ored into the flags value, then only these	429	If one or more of these are ored into the flags value, then only these
338	backends will be tried (in the reverse order as given here). If none are	430	backends will be tried (in the reverse order as listed here). If none are
339	specified, most compiled-in backend will be tried, usually in reverse	431	specified, all backends in C<ev_recommended_backends ()> will be tried.
340	order of their flag values :)
341		432
342	The most typical usage is like this:	433	The most typical usage is like this:
343		434
344	if (!ev_default_loop (0))	435	if (!ev_default_loop (0))
345	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	436	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
…		…
373	Destroys the default loop again (frees all memory and kernel state	464	Destroys the default loop again (frees all memory and kernel state
374	etc.). None of the active event watchers will be stopped in the normal	465	etc.). None of the active event watchers will be stopped in the normal
375	sense, so e.g. C<ev_is_active> might still return true. It is your	466	sense, so e.g. C<ev_is_active> might still return true. It is your
376	responsibility to either stop all watchers cleanly yoursef I<before>	467	responsibility to either stop all watchers cleanly yoursef I<before>
377	calling this function, or cope with the fact afterwards (which is usually	468	calling this function, or cope with the fact afterwards (which is usually
378	the easiest thing, youc na just ignore the watchers and/or C<free ()> them	469	the easiest thing, you can just ignore the watchers and/or C<free ()> them
379	for example).	470	for example).
		471
		472	Note that certain global state, such as signal state, will not be freed by
		473	this function, and related watchers (such as signal and child watchers)
		474	would need to be stopped manually.
		475
		476	In general it is not advisable to call this function except in the
		477	rare occasion where you really need to free e.g. the signal handling
		478	pipe fds. If you need dynamically allocated loops it is better to use
		479	C<ev_loop_new> and C<ev_loop_destroy>).
380		480
381	=item ev_loop_destroy (loop)	481	=item ev_loop_destroy (loop)
382		482
383	Like C<ev_default_destroy>, but destroys an event loop created by an	483	Like C<ev_default_destroy>, but destroys an event loop created by an
384	earlier call to C<ev_loop_new>.	484	earlier call to C<ev_loop_new>.
385		485
386	=item ev_default_fork ()	486	=item ev_default_fork ()
387		487
		488	This function sets a flag that causes subsequent C<ev_loop> iterations
388	This function reinitialises the kernel state for backends that have	489	to reinitialise the kernel state for backends that have one. Despite the
389	one. Despite the name, you can call it anytime, but it makes most sense	490	name, you can call it anytime, but it makes most sense after forking, in
390	after forking, in either the parent or child process (or both, but that	491	the child process (or both child and parent, but that again makes little
391	again makes little sense).	492	sense). You I<must> call it in the child before using any of the libev
		493	functions, and it will only take effect at the next C<ev_loop> iteration.
392		494
393	You I<must> call this function in the child process after forking if and	495	On the other hand, you only need to call this function in the child
394	only if you want to use the event library in both processes. If you just	496	process if and only if you want to use the event library in the child. If
395	fork+exec, you don't have to call it.	497	you just fork+exec, you don't have to call it at all.
396		498
397	The function itself is quite fast and it's usually not a problem to call	499	The function itself is quite fast and it's usually not a problem to call
398	it just in case after a fork. To make this easy, the function will fit in	500	it just in case after a fork. To make this easy, the function will fit in
399	quite nicely into a call to C<pthread_atfork>:	501	quite nicely into a call to C<pthread_atfork>:
400		502
401	pthread_atfork (0, 0, ev_default_fork);	503	pthread_atfork (0, 0, ev_default_fork);
402		504
403	At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use
404	without calling this function, so if you force one of those backends you
405	do not need to care.
406
407	=item ev_loop_fork (loop)	505	=item ev_loop_fork (loop)
408		506
409	Like C<ev_default_fork>, but acts on an event loop created by	507	Like C<ev_default_fork>, but acts on an event loop created by
410	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	508	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
411	after fork, and how you do this is entirely your own problem.	509	after fork, and how you do this is entirely your own problem.
		510
		511	=item unsigned int ev_loop_count (loop)
		512
		513	Returns the count of loop iterations for the loop, which is identical to
		514	the number of times libev did poll for new events. It starts at C<0> and
		515	happily wraps around with enough iterations.
		516
		517	This value can sometimes be useful as a generation counter of sorts (it
		518	"ticks" the number of loop iterations), as it roughly corresponds with
		519	C<ev_prepare> and C<ev_check> calls.
412		520
413	=item unsigned int ev_backend (loop)	521	=item unsigned int ev_backend (loop)
414		522
415	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	523	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
416	use.	524	use.
…		…
419		527
420	Returns the current "event loop time", which is the time the event loop	528	Returns the current "event loop time", which is the time the event loop
421	received events and started processing them. This timestamp does not	529	received events and started processing them. This timestamp does not
422	change as long as callbacks are being processed, and this is also the base	530	change as long as callbacks are being processed, and this is also the base
423	time used for relative timers. You can treat it as the timestamp of the	531	time used for relative timers. You can treat it as the timestamp of the
424	event occuring (or more correctly, libev finding out about it).	532	event occurring (or more correctly, libev finding out about it).
425		533
426	=item ev_loop (loop, int flags)	534	=item ev_loop (loop, int flags)
427		535
428	Finally, this is it, the event handler. This function usually is called	536	Finally, this is it, the event handler. This function usually is called
429	after you initialised all your watchers and you want to start handling	537	after you initialised all your watchers and you want to start handling
…		…
450	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	558	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
451	usually a better approach for this kind of thing.	559	usually a better approach for this kind of thing.
452		560
453	Here are the gory details of what C<ev_loop> does:	561	Here are the gory details of what C<ev_loop> does:
454		562
455	* If there are no active watchers (reference count is zero), return.	563	- Before the first iteration, call any pending watchers.
456	- Queue prepare watchers and then call all outstanding watchers.	564	* If EVFLAG_FORKCHECK was used, check for a fork.
		565	- If a fork was detected, queue and call all fork watchers.
		566	- Queue and call all prepare watchers.
457	- If we have been forked, recreate the kernel state.	567	- If we have been forked, recreate the kernel state.
458	- Update the kernel state with all outstanding changes.	568	- Update the kernel state with all outstanding changes.
459	- Update the "event loop time".	569	- Update the "event loop time".
460	- Calculate for how long to block.	570	- Calculate for how long to sleep or block, if at all
		571	(active idle watchers, EVLOOP_NONBLOCK or not having
		572	any active watchers at all will result in not sleeping).
		573	- Sleep if the I/O and timer collect interval say so.
461	- Block the process, waiting for any events.	574	- Block the process, waiting for any events.
462	- Queue all outstanding I/O (fd) events.	575	- Queue all outstanding I/O (fd) events.
463	- Update the "event loop time" and do time jump handling.	576	- Update the "event loop time" and do time jump handling.
464	- Queue all outstanding timers.	577	- Queue all outstanding timers.
465	- Queue all outstanding periodics.	578	- Queue all outstanding periodics.
466	- If no events are pending now, queue all idle watchers.	579	- If no events are pending now, queue all idle watchers.
467	- Queue all check watchers.	580	- Queue all check watchers.
468	- Call all queued watchers in reverse order (i.e. check watchers first).	581	- Call all queued watchers in reverse order (i.e. check watchers first).
469	Signals and child watchers are implemented as I/O watchers, and will	582	Signals and child watchers are implemented as I/O watchers, and will
470	be handled here by queueing them when their watcher gets executed.	583	be handled here by queueing them when their watcher gets executed.
471	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	584	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
472	were used, return, otherwise continue with step *.	585	were used, or there are no active watchers, return, otherwise
		586	continue with step *.
473		587
474	Example: Queue some jobs and then loop until no events are outsanding	588	Example: Queue some jobs and then loop until no events are outstanding
475	anymore.	589	anymore.
476		590
477	... queue jobs here, make sure they register event watchers as long	591	... queue jobs here, make sure they register event watchers as long
478	... as they still have work to do (even an idle watcher will do..)	592	... as they still have work to do (even an idle watcher will do..)
479	ev_loop (my_loop, 0);	593	ev_loop (my_loop, 0);
…		…
483		597
484	Can be used to make a call to C<ev_loop> return early (but only after it	598	Can be used to make a call to C<ev_loop> return early (but only after it
485	has processed all outstanding events). The C<how> argument must be either	599	has processed all outstanding events). The C<how> argument must be either
486	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	600	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or
487	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	601	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
		602
		603	This "unloop state" will be cleared when entering C<ev_loop> again.
488		604
489	=item ev_ref (loop)	605	=item ev_ref (loop)
490		606
491	=item ev_unref (loop)	607	=item ev_unref (loop)
492		608
…		…
497	returning, ev_unref() after starting, and ev_ref() before stopping it. For	613	returning, ev_unref() after starting, and ev_ref() before stopping it. For
498	example, libev itself uses this for its internal signal pipe: It is not	614	example, libev itself uses this for its internal signal pipe: It is not
499	visible to the libev user and should not keep C<ev_loop> from exiting if	615	visible to the libev user and should not keep C<ev_loop> from exiting if
500	no event watchers registered by it are active. It is also an excellent	616	no event watchers registered by it are active. It is also an excellent
501	way to do this for generic recurring timers or from within third-party	617	way to do this for generic recurring timers or from within third-party
502	libraries. Just remember to I<unref after start> and I<ref before stop>.	618	libraries. Just remember to I<unref after start> and I<ref before stop>
		619	(but only if the watcher wasn't active before, or was active before,
		620	respectively).
503		621
504	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	622	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
505	running when nothing else is active.	623	running when nothing else is active.
506		624
507	struct ev_signal exitsig;	625	struct ev_signal exitsig;
…		…
511		629
512	Example: For some weird reason, unregister the above signal handler again.	630	Example: For some weird reason, unregister the above signal handler again.
513		631
514	ev_ref (loop);	632	ev_ref (loop);
515	ev_signal_stop (loop, &exitsig);	633	ev_signal_stop (loop, &exitsig);
		634
		635	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
		636
		637	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
		638
		639	These advanced functions influence the time that libev will spend waiting
		640	for events. Both are by default C<0>, meaning that libev will try to
		641	invoke timer/periodic callbacks and I/O callbacks with minimum latency.
		642
		643	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
		644	allows libev to delay invocation of I/O and timer/periodic callbacks to
		645	increase efficiency of loop iterations.
		646
		647	The background is that sometimes your program runs just fast enough to
		648	handle one (or very few) event(s) per loop iteration. While this makes
		649	the program responsive, it also wastes a lot of CPU time to poll for new
		650	events, especially with backends like C<select ()> which have a high
		651	overhead for the actual polling but can deliver many events at once.
		652
		653	By setting a higher I<io collect interval> you allow libev to spend more
		654	time collecting I/O events, so you can handle more events per iteration,
		655	at the cost of increasing latency. Timeouts (both C<ev_periodic> and
		656	C<ev_timer>) will be not affected. Setting this to a non-null value will
		657	introduce an additional C<ev_sleep ()> call into most loop iterations.
		658
		659	Likewise, by setting a higher I<timeout collect interval> you allow libev
		660	to spend more time collecting timeouts, at the expense of increased
		661	latency (the watcher callback will be called later). C<ev_io> watchers
		662	will not be affected. Setting this to a non-null value will not introduce
		663	any overhead in libev.
		664
		665	Many (busy) programs can usually benefit by setting the io collect
		666	interval to a value near C<0.1> or so, which is often enough for
		667	interactive servers (of course not for games), likewise for timeouts. It
		668	usually doesn't make much sense to set it to a lower value than C<0.01>,
		669	as this approsaches the timing granularity of most systems.
516		670
517	=back	671	=back
518		672
519		673
520	=head1 ANATOMY OF A WATCHER	674	=head1 ANATOMY OF A WATCHER
…		…
700	=item bool ev_is_pending (ev_TYPE *watcher)	854	=item bool ev_is_pending (ev_TYPE *watcher)
701		855
702	Returns a true value iff the watcher is pending, (i.e. it has outstanding	856	Returns a true value iff the watcher is pending, (i.e. it has outstanding
703	events but its callback has not yet been invoked). As long as a watcher	857	events but its callback has not yet been invoked). As long as a watcher
704	is pending (but not active) you must not call an init function on it (but	858	is pending (but not active) you must not call an init function on it (but
705	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	859	C<ev_TYPE_set> is safe), you must not change its priority, and you must
706	libev (e.g. you cnanot C<free ()> it).	860	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		861	it).
707		862
708	=item callback ev_cb (ev_TYPE *watcher)	863	=item callback ev_cb (ev_TYPE *watcher)
709		864
710	Returns the callback currently set on the watcher.	865	Returns the callback currently set on the watcher.
711		866
712	=item ev_cb_set (ev_TYPE *watcher, callback)	867	=item ev_cb_set (ev_TYPE *watcher, callback)
713		868
714	Change the callback. You can change the callback at virtually any time	869	Change the callback. You can change the callback at virtually any time
715	(modulo threads).	870	(modulo threads).
		871
		872	=item ev_set_priority (ev_TYPE *watcher, priority)
		873
		874	=item int ev_priority (ev_TYPE *watcher)
		875
		876	Set and query the priority of the watcher. The priority is a small
		877	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		878	(default: C<-2>). Pending watchers with higher priority will be invoked
		879	before watchers with lower priority, but priority will not keep watchers
		880	from being executed (except for C<ev_idle> watchers).
		881
		882	This means that priorities are I<only> used for ordering callback
		883	invocation after new events have been received. This is useful, for
		884	example, to reduce latency after idling, or more often, to bind two
		885	watchers on the same event and make sure one is called first.
		886
		887	If you need to suppress invocation when higher priority events are pending
		888	you need to look at C<ev_idle> watchers, which provide this functionality.
		889
		890	You I<must not> change the priority of a watcher as long as it is active or
		891	pending.
		892
		893	The default priority used by watchers when no priority has been set is
		894	always C<0>, which is supposed to not be too high and not be too low :).
		895
		896	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		897	fine, as long as you do not mind that the priority value you query might
		898	or might not have been adjusted to be within valid range.
		899
		900	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		901
		902	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		903	C<loop> nor C<revents> need to be valid as long as the watcher callback
		904	can deal with that fact.
		905
		906	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		907
		908	If the watcher is pending, this function returns clears its pending status
		909	and returns its C<revents> bitset (as if its callback was invoked). If the
		910	watcher isn't pending it does nothing and returns C<0>.
716		911
717	=back	912	=back
718		913
719		914
720	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	915	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
805	In general you can register as many read and/or write event watchers per	1000	In general you can register as many read and/or write event watchers per
806	fd as you want (as long as you don't confuse yourself). Setting all file	1001	fd as you want (as long as you don't confuse yourself). Setting all file
807	descriptors to non-blocking mode is also usually a good idea (but not	1002	descriptors to non-blocking mode is also usually a good idea (but not
808	required if you know what you are doing).	1003	required if you know what you are doing).
809		1004
810	You have to be careful with dup'ed file descriptors, though. Some backends
811	(the linux epoll backend is a notable example) cannot handle dup'ed file
812	descriptors correctly if you register interest in two or more fds pointing
813	to the same underlying file/socket/etc. description (that is, they share
814	the same underlying "file open").
815
816	If you must do this, then force the use of a known-to-be-good backend	1005	If you must do this, then force the use of a known-to-be-good backend
817	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1006	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
818	C<EVBACKEND_POLL>).	1007	C<EVBACKEND_POLL>).
819		1008
820	Another thing you have to watch out for is that it is quite easy to	1009	Another thing you have to watch out for is that it is quite easy to
…		…
826	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1015	it is best to always use non-blocking I/O: An extra C<read>(2) returning
827	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1016	C<EAGAIN> is far preferable to a program hanging until some data arrives.
828		1017
829	If you cannot run the fd in non-blocking mode (for example you should not	1018	If you cannot run the fd in non-blocking mode (for example you should not
830	play around with an Xlib connection), then you have to seperately re-test	1019	play around with an Xlib connection), then you have to seperately re-test
831	wether a file descriptor is really ready with a known-to-be good interface	1020	whether a file descriptor is really ready with a known-to-be good interface
832	such as poll (fortunately in our Xlib example, Xlib already does this on	1021	such as poll (fortunately in our Xlib example, Xlib already does this on
833	its own, so its quite safe to use).	1022	its own, so its quite safe to use).
		1023
		1024	=head3 The special problem of disappearing file descriptors
		1025
		1026	Some backends (e.g. kqueue, epoll) need to be told about closing a file
		1027	descriptor (either by calling C<close> explicitly or by any other means,
		1028	such as C<dup>). The reason is that you register interest in some file
		1029	descriptor, but when it goes away, the operating system will silently drop
		1030	this interest. If another file descriptor with the same number then is
		1031	registered with libev, there is no efficient way to see that this is, in
		1032	fact, a different file descriptor.
		1033
		1034	To avoid having to explicitly tell libev about such cases, libev follows
		1035	the following policy: Each time C<ev_io_set> is being called, libev
		1036	will assume that this is potentially a new file descriptor, otherwise
		1037	it is assumed that the file descriptor stays the same. That means that
		1038	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		1039	descriptor even if the file descriptor number itself did not change.
		1040
		1041	This is how one would do it normally anyway, the important point is that
		1042	the libev application should not optimise around libev but should leave
		1043	optimisations to libev.
		1044
		1045	=head3 The special problem of dup'ed file descriptors
		1046
		1047	Some backends (e.g. epoll), cannot register events for file descriptors,
		1048	but only events for the underlying file descriptions. That means when you
		1049	have C<dup ()>'ed file descriptors or weirder constellations, and register
		1050	events for them, only one file descriptor might actually receive events.
		1051
		1052	There is no workaround possible except not registering events
		1053	for potentially C<dup ()>'ed file descriptors, or to resort to
		1054	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
		1055
		1056	=head3 The special problem of fork
		1057
		1058	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
		1059	useless behaviour. Libev fully supports fork, but needs to be told about
		1060	it in the child.
		1061
		1062	To support fork in your programs, you either have to call
		1063	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
		1064	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
		1065	C<EVBACKEND_POLL>.
		1066
		1067
		1068	=head3 Watcher-Specific Functions
834		1069
835	=over 4	1070	=over 4
836		1071
837	=item ev_io_init (ev_io *, callback, int fd, int events)	1072	=item ev_io_init (ev_io *, callback, int fd, int events)
838		1073
…		…
849	=item int events [read-only]	1084	=item int events [read-only]
850		1085
851	The events being watched.	1086	The events being watched.
852		1087
853	=back	1088	=back
		1089
		1090	=head3 Examples
854		1091
855	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1092	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
856	readable, but only once. Since it is likely line-buffered, you could	1093	readable, but only once. Since it is likely line-buffered, you could
857	attempt to read a whole line in the callback.	1094	attempt to read a whole line in the callback.
858		1095
…		…
892		1129
893	The callback is guarenteed to be invoked only when its timeout has passed,	1130	The callback is guarenteed to be invoked only when its timeout has passed,
894	but if multiple timers become ready during the same loop iteration then	1131	but if multiple timers become ready during the same loop iteration then
895	order of execution is undefined.	1132	order of execution is undefined.
896		1133
		1134	=head3 Watcher-Specific Functions and Data Members
		1135
897	=over 4	1136	=over 4
898		1137
899	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1138	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
900		1139
901	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1140	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
914	=item ev_timer_again (loop)	1153	=item ev_timer_again (loop)
915		1154
916	This will act as if the timer timed out and restart it again if it is	1155	This will act as if the timer timed out and restart it again if it is
917	repeating. The exact semantics are:	1156	repeating. The exact semantics are:
918		1157
		1158	If the timer is pending, its pending status is cleared.
		1159
919	If the timer is started but nonrepeating, stop it.	1160	If the timer is started but nonrepeating, stop it (as if it timed out).
920		1161
921	If the timer is repeating, either start it if necessary (with the repeat	1162	If the timer is repeating, either start it if necessary (with the
922	value), or reset the running timer to the repeat value.	1163	C<repeat> value), or reset the running timer to the C<repeat> value.
923		1164
924	This sounds a bit complicated, but here is a useful and typical	1165	This sounds a bit complicated, but here is a useful and typical
925	example: Imagine you have a tcp connection and you want a so-called	1166	example: Imagine you have a tcp connection and you want a so-called idle
926	idle timeout, that is, you want to be called when there have been,	1167	timeout, that is, you want to be called when there have been, say, 60
927	say, 60 seconds of inactivity on the socket. The easiest way to do	1168	seconds of inactivity on the socket. The easiest way to do this is to
928	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	1169	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
929	C<ev_timer_again> each time you successfully read or write some data. If	1170	C<ev_timer_again> each time you successfully read or write some data. If
930	you go into an idle state where you do not expect data to travel on the	1171	you go into an idle state where you do not expect data to travel on the
931	socket, you can stop the timer, and again will automatically restart it if	1172	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
932	need be.	1173	automatically restart it if need be.
933		1174
934	You can also ignore the C<after> value and C<ev_timer_start> altogether	1175	That means you can ignore the C<after> value and C<ev_timer_start>
935	and only ever use the C<repeat> value:	1176	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
936		1177
937	ev_timer_init (timer, callback, 0., 5.);	1178	ev_timer_init (timer, callback, 0., 5.);
938	ev_timer_again (loop, timer);	1179	ev_timer_again (loop, timer);
939	...	1180	...
940	timer->again = 17.;	1181	timer->again = 17.;
941	ev_timer_again (loop, timer);	1182	ev_timer_again (loop, timer);
942	...	1183	...
943	timer->again = 10.;	1184	timer->again = 10.;
944	ev_timer_again (loop, timer);	1185	ev_timer_again (loop, timer);
945		1186
946	This is more efficient then stopping/starting the timer eahc time you want	1187	This is more slightly efficient then stopping/starting the timer each time
947	to modify its timeout value.	1188	you want to modify its timeout value.
948		1189
949	=item ev_tstamp repeat [read-write]	1190	=item ev_tstamp repeat [read-write]
950		1191
951	The current C<repeat> value. Will be used each time the watcher times out	1192	The current C<repeat> value. Will be used each time the watcher times out
952	or C<ev_timer_again> is called and determines the next timeout (if any),	1193	or C<ev_timer_again> is called and determines the next timeout (if any),
953	which is also when any modifications are taken into account.	1194	which is also when any modifications are taken into account.
954		1195
955	=back	1196	=back
		1197
		1198	=head3 Examples
956		1199
957	Example: Create a timer that fires after 60 seconds.	1200	Example: Create a timer that fires after 60 seconds.
958		1201
959	static void	1202	static void
960	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1203	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
…		…
994	but on wallclock time (absolute time). You can tell a periodic watcher	1237	but on wallclock time (absolute time). You can tell a periodic watcher
995	to trigger "at" some specific point in time. For example, if you tell a	1238	to trigger "at" some specific point in time. For example, if you tell a
996	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1239	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
997	+ 10.>) and then reset your system clock to the last year, then it will	1240	+ 10.>) and then reset your system clock to the last year, then it will
998	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1241	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
999	roughly 10 seconds later and of course not if you reset your system time	1242	roughly 10 seconds later).
1000	again).
1001		1243
1002	They can also be used to implement vastly more complex timers, such as	1244	They can also be used to implement vastly more complex timers, such as
1003	triggering an event on eahc midnight, local time.	1245	triggering an event on each midnight, local time or other, complicated,
		1246	rules.
1004		1247
1005	As with timers, the callback is guarenteed to be invoked only when the	1248	As with timers, the callback is guarenteed to be invoked only when the
1006	time (C<at>) has been passed, but if multiple periodic timers become ready	1249	time (C<at>) has been passed, but if multiple periodic timers become ready
1007	during the same loop iteration then order of execution is undefined.	1250	during the same loop iteration then order of execution is undefined.
1008		1251
		1252	=head3 Watcher-Specific Functions and Data Members
		1253
1009	=over 4	1254	=over 4
1010		1255
1011	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1256	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
1012		1257
1013	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1258	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
1015	Lots of arguments, lets sort it out... There are basically three modes of	1260	Lots of arguments, lets sort it out... There are basically three modes of
1016	operation, and we will explain them from simplest to complex:	1261	operation, and we will explain them from simplest to complex:
1017		1262
1018	=over 4	1263	=over 4
1019		1264
1020	=item * absolute timer (interval = reschedule_cb = 0)	1265	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1021		1266
1022	In this configuration the watcher triggers an event at the wallclock time	1267	In this configuration the watcher triggers an event at the wallclock time
1023	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1268	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
1024	that is, if it is to be run at January 1st 2011 then it will run when the	1269	that is, if it is to be run at January 1st 2011 then it will run when the
1025	system time reaches or surpasses this time.	1270	system time reaches or surpasses this time.
1026		1271
1027	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1272	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1028		1273
1029	In this mode the watcher will always be scheduled to time out at the next	1274	In this mode the watcher will always be scheduled to time out at the next
1030	C<at + N * interval> time (for some integer N) and then repeat, regardless	1275	C<at + N * interval> time (for some integer N, which can also be negative)
1031	of any time jumps.	1276	and then repeat, regardless of any time jumps.
1032		1277
1033	This can be used to create timers that do not drift with respect to system	1278	This can be used to create timers that do not drift with respect to system
1034	time:	1279	time:
1035		1280
1036	ev_periodic_set (&periodic, 0., 3600., 0);	1281	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1042		1287
1043	Another way to think about it (for the mathematically inclined) is that	1288	Another way to think about it (for the mathematically inclined) is that
1044	C<ev_periodic> will try to run the callback in this mode at the next possible	1289	C<ev_periodic> will try to run the callback in this mode at the next possible
1045	time where C<time = at (mod interval)>, regardless of any time jumps.	1290	time where C<time = at (mod interval)>, regardless of any time jumps.
1046		1291
		1292	For numerical stability it is preferable that the C<at> value is near
		1293	C<ev_now ()> (the current time), but there is no range requirement for
		1294	this value.
		1295
1047	=item * manual reschedule mode (reschedule_cb = callback)	1296	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1048		1297
1049	In this mode the values for C<interval> and C<at> are both being	1298	In this mode the values for C<interval> and C<at> are both being
1050	ignored. Instead, each time the periodic watcher gets scheduled, the	1299	ignored. Instead, each time the periodic watcher gets scheduled, the
1051	reschedule callback will be called with the watcher as first, and the	1300	reschedule callback will be called with the watcher as first, and the
1052	current time as second argument.	1301	current time as second argument.
1053		1302
1054	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1303	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1055	ever, or make any event loop modifications>. If you need to stop it,	1304	ever, or make any event loop modifications>. If you need to stop it,
1056	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1305	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1057	starting a prepare watcher).	1306	starting an C<ev_prepare> watcher, which is legal).
1058		1307
1059	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1308	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1060	ev_tstamp now)>, e.g.:	1309	ev_tstamp now)>, e.g.:
1061		1310
1062	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1311	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1085	Simply stops and restarts the periodic watcher again. This is only useful	1334	Simply stops and restarts the periodic watcher again. This is only useful
1086	when you changed some parameters or the reschedule callback would return	1335	when you changed some parameters or the reschedule callback would return
1087	a different time than the last time it was called (e.g. in a crond like	1336	a different time than the last time it was called (e.g. in a crond like
1088	program when the crontabs have changed).	1337	program when the crontabs have changed).
1089		1338
		1339	=item ev_tstamp offset [read-write]
		1340
		1341	When repeating, this contains the offset value, otherwise this is the
		1342	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1343
		1344	Can be modified any time, but changes only take effect when the periodic
		1345	timer fires or C<ev_periodic_again> is being called.
		1346
1090	=item ev_tstamp interval [read-write]	1347	=item ev_tstamp interval [read-write]
1091		1348
1092	The current interval value. Can be modified any time, but changes only	1349	The current interval value. Can be modified any time, but changes only
1093	take effect when the periodic timer fires or C<ev_periodic_again> is being	1350	take effect when the periodic timer fires or C<ev_periodic_again> is being
1094	called.	1351	called.
…		…
1097		1354
1098	The current reschedule callback, or C<0>, if this functionality is	1355	The current reschedule callback, or C<0>, if this functionality is
1099	switched off. Can be changed any time, but changes only take effect when	1356	switched off. Can be changed any time, but changes only take effect when
1100	the periodic timer fires or C<ev_periodic_again> is being called.	1357	the periodic timer fires or C<ev_periodic_again> is being called.
1101		1358
		1359	=item ev_tstamp at [read-only]
		1360
		1361	When active, contains the absolute time that the watcher is supposed to
		1362	trigger next.
		1363
1102	=back	1364	=back
		1365
		1366	=head3 Examples
1103		1367
1104	Example: Call a callback every hour, or, more precisely, whenever the	1368	Example: Call a callback every hour, or, more precisely, whenever the
1105	system clock is divisible by 3600. The callback invocation times have	1369	system clock is divisible by 3600. The callback invocation times have
1106	potentially a lot of jittering, but good long-term stability.	1370	potentially a lot of jittering, but good long-term stability.
1107		1371
…		…
1147	with the kernel (thus it coexists with your own signal handlers as long	1411	with the kernel (thus it coexists with your own signal handlers as long
1148	as you don't register any with libev). Similarly, when the last signal	1412	as you don't register any with libev). Similarly, when the last signal
1149	watcher for a signal is stopped libev will reset the signal handler to	1413	watcher for a signal is stopped libev will reset the signal handler to
1150	SIG_DFL (regardless of what it was set to before).	1414	SIG_DFL (regardless of what it was set to before).
1151		1415
		1416	=head3 Watcher-Specific Functions and Data Members
		1417
1152	=over 4	1418	=over 4
1153		1419
1154	=item ev_signal_init (ev_signal *, callback, int signum)	1420	=item ev_signal_init (ev_signal *, callback, int signum)
1155		1421
1156	=item ev_signal_set (ev_signal *, int signum)	1422	=item ev_signal_set (ev_signal *, int signum)
…		…
1168	=head2 C<ev_child> - watch out for process status changes	1434	=head2 C<ev_child> - watch out for process status changes
1169		1435
1170	Child watchers trigger when your process receives a SIGCHLD in response to	1436	Child watchers trigger when your process receives a SIGCHLD in response to
1171	some child status changes (most typically when a child of yours dies).	1437	some child status changes (most typically when a child of yours dies).
1172		1438
		1439	=head3 Watcher-Specific Functions and Data Members
		1440
1173	=over 4	1441	=over 4
1174		1442
1175	=item ev_child_init (ev_child *, callback, int pid)	1443	=item ev_child_init (ev_child *, callback, int pid, int trace)
1176		1444
1177	=item ev_child_set (ev_child *, int pid)	1445	=item ev_child_set (ev_child *, int pid, int trace)
1178		1446
1179	Configures the watcher to wait for status changes of process C<pid> (or	1447	Configures the watcher to wait for status changes of process C<pid> (or
1180	I<any> process if C<pid> is specified as C<0>). The callback can look	1448	I<any> process if C<pid> is specified as C<0>). The callback can look
1181	at the C<rstatus> member of the C<ev_child> watcher structure to see	1449	at the C<rstatus> member of the C<ev_child> watcher structure to see
1182	the status word (use the macros from C<sys/wait.h> and see your systems	1450	the status word (use the macros from C<sys/wait.h> and see your systems
1183	C<waitpid> documentation). The C<rpid> member contains the pid of the	1451	C<waitpid> documentation). The C<rpid> member contains the pid of the
1184	process causing the status change.	1452	process causing the status change. C<trace> must be either C<0> (only
		1453	activate the watcher when the process terminates) or C<1> (additionally
		1454	activate the watcher when the process is stopped or continued).
1185		1455
1186	=item int pid [read-only]	1456	=item int pid [read-only]
1187		1457
1188	The process id this watcher watches out for, or C<0>, meaning any process id.	1458	The process id this watcher watches out for, or C<0>, meaning any process id.
1189		1459
…		…
1195		1465
1196	The process exit/trace status caused by C<rpid> (see your systems	1466	The process exit/trace status caused by C<rpid> (see your systems
1197	C<waitpid> and C<sys/wait.h> documentation for details).	1467	C<waitpid> and C<sys/wait.h> documentation for details).
1198		1468
1199	=back	1469	=back
		1470
		1471	=head3 Examples
1200		1472
1201	Example: Try to exit cleanly on SIGINT and SIGTERM.	1473	Example: Try to exit cleanly on SIGINT and SIGTERM.
1202		1474
1203	static void	1475	static void
1204	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1476	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
…		…
1221	not exist" is a status change like any other. The condition "path does	1493	not exist" is a status change like any other. The condition "path does
1222	not exist" is signified by the C<st_nlink> field being zero (which is	1494	not exist" is signified by the C<st_nlink> field being zero (which is
1223	otherwise always forced to be at least one) and all the other fields of	1495	otherwise always forced to be at least one) and all the other fields of
1224	the stat buffer having unspecified contents.	1496	the stat buffer having unspecified contents.
1225		1497
		1498	The path I<should> be absolute and I<must not> end in a slash. If it is
		1499	relative and your working directory changes, the behaviour is undefined.
		1500
1226	Since there is no standard to do this, the portable implementation simply	1501	Since there is no standard to do this, the portable implementation simply
1227	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1502	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1228	can specify a recommended polling interval for this case. If you specify	1503	can specify a recommended polling interval for this case. If you specify
1229	a polling interval of C<0> (highly recommended!) then a I<suitable,	1504	a polling interval of C<0> (highly recommended!) then a I<suitable,
1230	unspecified default> value will be used (which you can expect to be around	1505	unspecified default> value will be used (which you can expect to be around
1231	five seconds, although this might change dynamically). Libev will also	1506	five seconds, although this might change dynamically). Libev will also
1232	impose a minimum interval which is currently around C<0.1>, but thats	1507	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1234		1509
1235	This watcher type is not meant for massive numbers of stat watchers,	1510	This watcher type is not meant for massive numbers of stat watchers,
1236	as even with OS-supported change notifications, this can be	1511	as even with OS-supported change notifications, this can be
1237	resource-intensive.	1512	resource-intensive.
1238		1513
1239	At the time of this writing, no specific OS backends are implemented, but	1514	At the time of this writing, only the Linux inotify interface is
1240	if demand increases, at least a kqueue and inotify backend will be added.	1515	implemented (implementing kqueue support is left as an exercise for the
		1516	reader). Inotify will be used to give hints only and should not change the
		1517	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1518	to fall back to regular polling again even with inotify, but changes are
		1519	usually detected immediately, and if the file exists there will be no
		1520	polling.
		1521
		1522	=head3 Inotify
		1523
		1524	When C<inotify (7)> support has been compiled into libev (generally only
		1525	available on Linux) and present at runtime, it will be used to speed up
		1526	change detection where possible. The inotify descriptor will be created lazily
		1527	when the first C<ev_stat> watcher is being started.
		1528
		1529	Inotify presense does not change the semantics of C<ev_stat> watchers
		1530	except that changes might be detected earlier, and in some cases, to avoid
		1531	making regular C<stat> calls. Even in the presense of inotify support
		1532	there are many cases where libev has to resort to regular C<stat> polling.
		1533
		1534	(There is no support for kqueue, as apparently it cannot be used to
		1535	implement this functionality, due to the requirement of having a file
		1536	descriptor open on the object at all times).
		1537
		1538	=head3 The special problem of stat time resolution
		1539
		1540	The C<stat ()> syscall only supports full-second resolution portably, and
		1541	even on systems where the resolution is higher, many filesystems still
		1542	only support whole seconds.
		1543
		1544	That means that, if the time is the only thing that changes, you might
		1545	miss updates: on the first update, C<ev_stat> detects a change and calls
		1546	your callback, which does something. When there is another update within
		1547	the same second, C<ev_stat> will be unable to detect it.
		1548
		1549	The solution to this is to delay acting on a change for a second (or till
		1550	the next second boundary), using a roughly one-second delay C<ev_timer>
		1551	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>
		1552	is added to work around small timing inconsistencies of some operating
		1553	systems.
		1554
		1555	=head3 Watcher-Specific Functions and Data Members
1241		1556
1242	=over 4	1557	=over 4
1243		1558
1244	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)	1559	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
1245		1560
…		…
1281	=item const char *path [read-only]	1596	=item const char *path [read-only]
1282		1597
1283	The filesystem path that is being watched.	1598	The filesystem path that is being watched.
1284		1599
1285	=back	1600	=back
		1601
		1602	=head3 Examples
1286		1603
1287	Example: Watch C</etc/passwd> for attribute changes.	1604	Example: Watch C</etc/passwd> for attribute changes.
1288		1605
1289	static void	1606	static void
1290	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1607	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
…		…
1303	}	1620	}
1304		1621
1305	...	1622	...
1306	ev_stat passwd;	1623	ev_stat passwd;
1307		1624
1308	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");	1625	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1309	ev_stat_start (loop, &passwd);	1626	ev_stat_start (loop, &passwd);
1310		1627
		1628	Example: Like above, but additionally use a one-second delay so we do not
		1629	miss updates (however, frequent updates will delay processing, too, so
		1630	one might do the work both on C<ev_stat> callback invocation I<and> on
		1631	C<ev_timer> callback invocation).
		1632
		1633	static ev_stat passwd;
		1634	static ev_timer timer;
		1635
		1636	static void
		1637	timer_cb (EV_P_ ev_timer *w, int revents)
		1638	{
		1639	ev_timer_stop (EV_A_ w);
		1640
		1641	/* now it's one second after the most recent passwd change */
		1642	}
		1643
		1644	static void
		1645	stat_cb (EV_P_ ev_stat *w, int revents)
		1646	{
		1647	/* reset the one-second timer */
		1648	ev_timer_again (EV_A_ &timer);
		1649	}
		1650
		1651	...
		1652	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
		1653	ev_stat_start (loop, &passwd);
		1654	ev_timer_init (&timer, timer_cb, 0., 1.01);
		1655
1311		1656
1312	=head2 C<ev_idle> - when you've got nothing better to do...	1657	=head2 C<ev_idle> - when you've got nothing better to do...
1313		1658
1314	Idle watchers trigger events when there are no other events are pending	1659	Idle watchers trigger events when no other events of the same or higher
1315	(prepare, check and other idle watchers do not count). That is, as long	1660	priority are pending (prepare, check and other idle watchers do not
1316	as your process is busy handling sockets or timeouts (or even signals,	1661	count).
1317	imagine) it will not be triggered. But when your process is idle all idle	1662
1318	watchers are being called again and again, once per event loop iteration -	1663	That is, as long as your process is busy handling sockets or timeouts
		1664	(or even signals, imagine) of the same or higher priority it will not be
		1665	triggered. But when your process is idle (or only lower-priority watchers
		1666	are pending), the idle watchers are being called once per event loop
1319	until stopped, that is, or your process receives more events and becomes	1667	iteration - until stopped, that is, or your process receives more events
1320	busy.	1668	and becomes busy again with higher priority stuff.
1321		1669
1322	The most noteworthy effect is that as long as any idle watchers are	1670	The most noteworthy effect is that as long as any idle watchers are
1323	active, the process will not block when waiting for new events.	1671	active, the process will not block when waiting for new events.
1324		1672
1325	Apart from keeping your process non-blocking (which is a useful	1673	Apart from keeping your process non-blocking (which is a useful
1326	effect on its own sometimes), idle watchers are a good place to do	1674	effect on its own sometimes), idle watchers are a good place to do
1327	"pseudo-background processing", or delay processing stuff to after the	1675	"pseudo-background processing", or delay processing stuff to after the
1328	event loop has handled all outstanding events.	1676	event loop has handled all outstanding events.
1329		1677
		1678	=head3 Watcher-Specific Functions and Data Members
		1679
1330	=over 4	1680	=over 4
1331		1681
1332	=item ev_idle_init (ev_signal *, callback)	1682	=item ev_idle_init (ev_signal *, callback)
1333		1683
1334	Initialises and configures the idle watcher - it has no parameters of any	1684	Initialises and configures the idle watcher - it has no parameters of any
1335	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1685	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1336	believe me.	1686	believe me.
1337		1687
1338	=back	1688	=back
		1689
		1690	=head3 Examples
1339		1691
1340	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1692	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1341	callback, free it. Also, use no error checking, as usual.	1693	callback, free it. Also, use no error checking, as usual.
1342		1694
1343	static void	1695	static void
1344	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1696	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1345	{	1697	{
1346	free (w);	1698	free (w);
1347	// now do something you wanted to do when the program has	1699	// now do something you wanted to do when the program has
1348	// no longer asnything immediate to do.	1700	// no longer anything immediate to do.
1349	}	1701	}
1350		1702
1351	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1703	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1352	ev_idle_init (idle_watcher, idle_cb);	1704	ev_idle_init (idle_watcher, idle_cb);
1353	ev_idle_start (loop, idle_cb);	1705	ev_idle_start (loop, idle_cb);
…		…
1391	with priority higher than or equal to the event loop and one coroutine	1743	with priority higher than or equal to the event loop and one coroutine
1392	of lower priority, but only once, using idle watchers to keep the event	1744	of lower priority, but only once, using idle watchers to keep the event
1393	loop from blocking if lower-priority coroutines are active, thus mapping	1745	loop from blocking if lower-priority coroutines are active, thus mapping
1394	low-priority coroutines to idle/background tasks).	1746	low-priority coroutines to idle/background tasks).
1395		1747
		1748	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1749	priority, to ensure that they are being run before any other watchers
		1750	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1751	too) should not activate ("feed") events into libev. While libev fully
		1752	supports this, they will be called before other C<ev_check> watchers
		1753	did their job. As C<ev_check> watchers are often used to embed other
		1754	(non-libev) event loops those other event loops might be in an unusable
		1755	state until their C<ev_check> watcher ran (always remind yourself to
		1756	coexist peacefully with others).
		1757
		1758	=head3 Watcher-Specific Functions and Data Members
		1759
1396	=over 4	1760	=over 4
1397		1761
1398	=item ev_prepare_init (ev_prepare *, callback)	1762	=item ev_prepare_init (ev_prepare *, callback)
1399		1763
1400	=item ev_check_init (ev_check *, callback)	1764	=item ev_check_init (ev_check *, callback)
…		…
1403	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1767	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1404	macros, but using them is utterly, utterly and completely pointless.	1768	macros, but using them is utterly, utterly and completely pointless.
1405		1769
1406	=back	1770	=back
1407		1771
1408	Example: To include a library such as adns, you would add IO watchers	1772	=head3 Examples
1409	and a timeout watcher in a prepare handler, as required by libadns, and	1773
		1774	There are a number of principal ways to embed other event loops or modules
		1775	into libev. Here are some ideas on how to include libadns into libev
		1776	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1777	use for an actually working example. Another Perl module named C<EV::Glib>
		1778	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1779	into the Glib event loop).
		1780
		1781	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1410	in a check watcher, destroy them and call into libadns. What follows is	1782	and in a check watcher, destroy them and call into libadns. What follows
1411	pseudo-code only of course:	1783	is pseudo-code only of course. This requires you to either use a low
		1784	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1785	the callbacks for the IO/timeout watchers might not have been called yet.
1412		1786
1413	static ev_io iow [nfd];	1787	static ev_io iow [nfd];
1414	static ev_timer tw;	1788	static ev_timer tw;
1415		1789
1416	static void	1790	static void
1417	io_cb (ev_loop *loop, ev_io *w, int revents)	1791	io_cb (ev_loop *loop, ev_io *w, int revents)
1418	{	1792	{
1419	// set the relevant poll flags
1420	// could also call adns_processreadable etc. here
1421	struct pollfd *fd = (struct pollfd *)w->data;
1422	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1423	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1424	}	1793	}
1425		1794
1426	// create io watchers for each fd and a timer before blocking	1795	// create io watchers for each fd and a timer before blocking
1427	static void	1796	static void
1428	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1797	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1429	{	1798	{
1430	int timeout = 3600000;truct pollfd fds [nfd];	1799	int timeout = 3600000;
		1800	struct pollfd fds [nfd];
1431	// actual code will need to loop here and realloc etc.	1801	// actual code will need to loop here and realloc etc.
1432	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1802	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1433		1803
1434	/* the callback is illegal, but won't be called as we stop during check */	1804	/* the callback is illegal, but won't be called as we stop during check */
1435	ev_timer_init (&tw, 0, timeout * 1e-3);	1805	ev_timer_init (&tw, 0, timeout * 1e-3);
1436	ev_timer_start (loop, &tw);	1806	ev_timer_start (loop, &tw);
1437		1807
1438	// create on ev_io per pollfd	1808	// create one ev_io per pollfd
1439	for (int i = 0; i < nfd; ++i)	1809	for (int i = 0; i < nfd; ++i)
1440	{	1810	{
1441	ev_io_init (iow + i, io_cb, fds [i].fd,	1811	ev_io_init (iow + i, io_cb, fds [i].fd,
1442	((fds [i].events & POLLIN ? EV_READ : 0)	1812	((fds [i].events & POLLIN ? EV_READ : 0)
1443	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1813	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1444		1814
1445	fds [i].revents = 0;	1815	fds [i].revents = 0;
1446	iow [i].data = fds + i;
1447	ev_io_start (loop, iow + i);	1816	ev_io_start (loop, iow + i);
1448	}	1817	}
1449	}	1818	}
1450		1819
1451	// stop all watchers after blocking	1820	// stop all watchers after blocking
…		…
1453	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1822	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1454	{	1823	{
1455	ev_timer_stop (loop, &tw);	1824	ev_timer_stop (loop, &tw);
1456		1825
1457	for (int i = 0; i < nfd; ++i)	1826	for (int i = 0; i < nfd; ++i)
		1827	{
		1828	// set the relevant poll flags
		1829	// could also call adns_processreadable etc. here
		1830	struct pollfd *fd = fds + i;
		1831	int revents = ev_clear_pending (iow + i);
		1832	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1833	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1834
		1835	// now stop the watcher
1458	ev_io_stop (loop, iow + i);	1836	ev_io_stop (loop, iow + i);
		1837	}
1459		1838
1460	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1839	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1840	}
		1841
		1842	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1843	in the prepare watcher and would dispose of the check watcher.
		1844
		1845	Method 3: If the module to be embedded supports explicit event
		1846	notification (adns does), you can also make use of the actual watcher
		1847	callbacks, and only destroy/create the watchers in the prepare watcher.
		1848
		1849	static void
		1850	timer_cb (EV_P_ ev_timer *w, int revents)
		1851	{
		1852	adns_state ads = (adns_state)w->data;
		1853	update_now (EV_A);
		1854
		1855	adns_processtimeouts (ads, &tv_now);
		1856	}
		1857
		1858	static void
		1859	io_cb (EV_P_ ev_io *w, int revents)
		1860	{
		1861	adns_state ads = (adns_state)w->data;
		1862	update_now (EV_A);
		1863
		1864	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1865	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1866	}
		1867
		1868	// do not ever call adns_afterpoll
		1869
		1870	Method 4: Do not use a prepare or check watcher because the module you
		1871	want to embed is too inflexible to support it. Instead, youc na override
		1872	their poll function. The drawback with this solution is that the main
		1873	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1874	this.
		1875
		1876	static gint
		1877	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1878	{
		1879	int got_events = 0;
		1880
		1881	for (n = 0; n < nfds; ++n)
		1882	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1883
		1884	if (timeout >= 0)
		1885	// create/start timer
		1886
		1887	// poll
		1888	ev_loop (EV_A_ 0);
		1889
		1890	// stop timer again
		1891	if (timeout >= 0)
		1892	ev_timer_stop (EV_A_ &to);
		1893
		1894	// stop io watchers again - their callbacks should have set
		1895	for (n = 0; n < nfds; ++n)
		1896	ev_io_stop (EV_A_ iow [n]);
		1897
		1898	return got_events;
1461	}	1899	}
1462		1900
1463		1901
1464	=head2 C<ev_embed> - when one backend isn't enough...	1902	=head2 C<ev_embed> - when one backend isn't enough...
1465		1903
…		…
1508	portable one.	1946	portable one.
1509		1947
1510	So when you want to use this feature you will always have to be prepared	1948	So when you want to use this feature you will always have to be prepared
1511	that you cannot get an embeddable loop. The recommended way to get around	1949	that you cannot get an embeddable loop. The recommended way to get around
1512	this is to have a separate variables for your embeddable loop, try to	1950	this is to have a separate variables for your embeddable loop, try to
1513	create it, and if that fails, use the normal loop for everything:	1951	create it, and if that fails, use the normal loop for everything.
		1952
		1953	=head3 Watcher-Specific Functions and Data Members
		1954
		1955	=over 4
		1956
		1957	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
		1958
		1959	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)
		1960
		1961	Configures the watcher to embed the given loop, which must be
		1962	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
		1963	invoked automatically, otherwise it is the responsibility of the callback
		1964	to invoke it (it will continue to be called until the sweep has been done,
		1965	if you do not want thta, you need to temporarily stop the embed watcher).
		1966
		1967	=item ev_embed_sweep (loop, ev_embed *)
		1968
		1969	Make a single, non-blocking sweep over the embedded loop. This works
		1970	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
		1971	apropriate way for embedded loops.
		1972
		1973	=item struct ev_loop *other [read-only]
		1974
		1975	The embedded event loop.
		1976
		1977	=back
		1978
		1979	=head3 Examples
		1980
		1981	Example: Try to get an embeddable event loop and embed it into the default
		1982	event loop. If that is not possible, use the default loop. The default
		1983	loop is stored in C<loop_hi>, while the mebeddable loop is stored in
		1984	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be
		1985	used).
1514		1986
1515	struct ev_loop *loop_hi = ev_default_init (0);	1987	struct ev_loop *loop_hi = ev_default_init (0);
1516	struct ev_loop *loop_lo = 0;	1988	struct ev_loop *loop_lo = 0;
1517	struct ev_embed embed;	1989	struct ev_embed embed;
1518		1990
…		…
1529	ev_embed_start (loop_hi, &embed);	2001	ev_embed_start (loop_hi, &embed);
1530	}	2002	}
1531	else	2003	else
1532	loop_lo = loop_hi;	2004	loop_lo = loop_hi;
1533		2005
1534	=over 4	2006	Example: Check if kqueue is available but not recommended and create
		2007	a kqueue backend for use with sockets (which usually work with any
		2008	kqueue implementation). Store the kqueue/socket-only event loop in
		2009	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
1535		2010
1536	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)	2011	struct ev_loop *loop = ev_default_init (0);
		2012	struct ev_loop *loop_socket = 0;
		2013	struct ev_embed embed;
		2014
		2015	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
		2016	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
		2017	{
		2018	ev_embed_init (&embed, 0, loop_socket);
		2019	ev_embed_start (loop, &embed);
		2020	}
1537		2021
1538	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	2022	if (!loop_socket)
		2023	loop_socket = loop;
1539		2024
1540	Configures the watcher to embed the given loop, which must be	2025	// now use loop_socket for all sockets, and loop for everything else
1541	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
1542	invoked automatically, otherwise it is the responsibility of the callback
1543	to invoke it (it will continue to be called until the sweep has been done,
1544	if you do not want thta, you need to temporarily stop the embed watcher).
1545
1546	=item ev_embed_sweep (loop, ev_embed *)
1547
1548	Make a single, non-blocking sweep over the embedded loop. This works
1549	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1550	apropriate way for embedded loops.
1551
1552	=item struct ev_loop *loop [read-only]
1553
1554	The embedded event loop.
1555
1556	=back
1557		2026
1558		2027
1559	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2028	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
1560		2029
1561	Fork watchers are called when a C<fork ()> was detected (usually because	2030	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
1564	event loop blocks next and before C<ev_check> watchers are being called,	2033	event loop blocks next and before C<ev_check> watchers are being called,
1565	and only in the child after the fork. If whoever good citizen calling	2034	and only in the child after the fork. If whoever good citizen calling
1566	C<ev_default_fork> cheats and calls it in the wrong process, the fork	2035	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1567	handlers will be invoked, too, of course.	2036	handlers will be invoked, too, of course.
1568		2037
		2038	=head3 Watcher-Specific Functions and Data Members
		2039
1569	=over 4	2040	=over 4
1570		2041
1571	=item ev_fork_init (ev_signal *, callback)	2042	=item ev_fork_init (ev_signal *, callback)
1572		2043
1573	Initialises and configures the fork watcher - it has no parameters of any	2044	Initialises and configures the fork watcher - it has no parameters of any
…		…
1669		2140
1670	To use it,	2141	To use it,
1671		2142
1672	#include <ev++.h>	2143	#include <ev++.h>
1673		2144
1674	(it is not installed by default). This automatically includes F<ev.h>	2145	This automatically includes F<ev.h> and puts all of its definitions (many
1675	and puts all of its definitions (many of them macros) into the global	2146	of them macros) into the global namespace. All C++ specific things are
1676	namespace. All C++ specific things are put into the C<ev> namespace.	2147	put into the C<ev> namespace. It should support all the same embedding
		2148	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1677		2149
1678	It should support all the same embedding options as F<ev.h>, most notably	2150	Care has been taken to keep the overhead low. The only data member the C++
1679	C<EV_MULTIPLICITY>.	2151	classes add (compared to plain C-style watchers) is the event loop pointer
		2152	that the watcher is associated with (or no additional members at all if
		2153	you disable C<EV_MULTIPLICITY> when embedding libev).
		2154
		2155	Currently, functions, and static and non-static member functions can be
		2156	used as callbacks. Other types should be easy to add as long as they only
		2157	need one additional pointer for context. If you need support for other
		2158	types of functors please contact the author (preferably after implementing
		2159	it).
1680		2160
1681	Here is a list of things available in the C<ev> namespace:	2161	Here is a list of things available in the C<ev> namespace:
1682		2162
1683	=over 4	2163	=over 4
1684		2164
…		…
1700		2180
1701	All of those classes have these methods:	2181	All of those classes have these methods:
1702		2182
1703	=over 4	2183	=over 4
1704		2184
1705	=item ev::TYPE::TYPE (object *, object::method *)	2185	=item ev::TYPE::TYPE ()
1706		2186
1707	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)	2187	=item ev::TYPE::TYPE (struct ev_loop *)
1708		2188
1709	=item ev::TYPE::~TYPE	2189	=item ev::TYPE::~TYPE
1710		2190
1711	The constructor takes a pointer to an object and a method pointer to	2191	The constructor (optionally) takes an event loop to associate the watcher
1712	the event handler callback to call in this class. The constructor calls	2192	with. If it is omitted, it will use C<EV_DEFAULT>.
1713	C<ev_init> for you, which means you have to call the C<set> method	2193
1714	before starting it. If you do not specify a loop then the constructor	2194	The constructor calls C<ev_init> for you, which means you have to call the
1715	automatically associates the default loop with this watcher.	2195	C<set> method before starting it.
		2196
		2197	It will not set a callback, however: You have to call the templated C<set>
		2198	method to set a callback before you can start the watcher.
		2199
		2200	(The reason why you have to use a method is a limitation in C++ which does
		2201	not allow explicit template arguments for constructors).
1716		2202
1717	The destructor automatically stops the watcher if it is active.	2203	The destructor automatically stops the watcher if it is active.
		2204
		2205	=item w->set<class, &class::method> (object *)
		2206
		2207	This method sets the callback method to call. The method has to have a
		2208	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		2209	first argument and the C<revents> as second. The object must be given as
		2210	parameter and is stored in the C<data> member of the watcher.
		2211
		2212	This method synthesizes efficient thunking code to call your method from
		2213	the C callback that libev requires. If your compiler can inline your
		2214	callback (i.e. it is visible to it at the place of the C<set> call and
		2215	your compiler is good :), then the method will be fully inlined into the
		2216	thunking function, making it as fast as a direct C callback.
		2217
		2218	Example: simple class declaration and watcher initialisation
		2219
		2220	struct myclass
		2221	{
		2222	void io_cb (ev::io &w, int revents) { }
		2223	}
		2224
		2225	myclass obj;
		2226	ev::io iow;
		2227	iow.set <myclass, &myclass::io_cb> (&obj);
		2228
		2229	=item w->set<function> (void *data = 0)
		2230
		2231	Also sets a callback, but uses a static method or plain function as
		2232	callback. The optional C<data> argument will be stored in the watcher's
		2233	C<data> member and is free for you to use.
		2234
		2235	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2236
		2237	See the method-C<set> above for more details.
		2238
		2239	Example:
		2240
		2241	static void io_cb (ev::io &w, int revents) { }
		2242	iow.set <io_cb> ();
1718		2243
1719	=item w->set (struct ev_loop *)	2244	=item w->set (struct ev_loop *)
1720		2245
1721	Associates a different C<struct ev_loop> with this watcher. You can only	2246	Associates a different C<struct ev_loop> with this watcher. You can only
1722	do this when the watcher is inactive (and not pending either).	2247	do this when the watcher is inactive (and not pending either).
1723		2248
1724	=item w->set ([args])	2249	=item w->set ([args])
1725		2250
1726	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2251	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1727	called at least once. Unlike the C counterpart, an active watcher gets	2252	called at least once. Unlike the C counterpart, an active watcher gets
1728	automatically stopped and restarted.	2253	automatically stopped and restarted when reconfiguring it with this
		2254	method.
1729		2255
1730	=item w->start ()	2256	=item w->start ()
1731		2257
1732	Starts the watcher. Note that there is no C<loop> argument as the	2258	Starts the watcher. Note that there is no C<loop> argument, as the
1733	constructor already takes the loop.	2259	constructor already stores the event loop.
1734		2260
1735	=item w->stop ()	2261	=item w->stop ()
1736		2262
1737	Stops the watcher if it is active. Again, no C<loop> argument.	2263	Stops the watcher if it is active. Again, no C<loop> argument.
1738		2264
1739	=item w->again () C<ev::timer>, C<ev::periodic> only	2265	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1740		2266
1741	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2267	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1742	C<ev_TYPE_again> function.	2268	C<ev_TYPE_again> function.
1743		2269
1744	=item w->sweep () C<ev::embed> only	2270	=item w->sweep () (C<ev::embed> only)
1745		2271
1746	Invokes C<ev_embed_sweep>.	2272	Invokes C<ev_embed_sweep>.
1747		2273
1748	=item w->update () C<ev::stat> only	2274	=item w->update () (C<ev::stat> only)
1749		2275
1750	Invokes C<ev_stat_stat>.	2276	Invokes C<ev_stat_stat>.
1751		2277
1752	=back	2278	=back
1753		2279
…		…
1756	Example: Define a class with an IO and idle watcher, start one of them in	2282	Example: Define a class with an IO and idle watcher, start one of them in
1757	the constructor.	2283	the constructor.
1758		2284
1759	class myclass	2285	class myclass
1760	{	2286	{
1761	ev_io io; void io_cb (ev::io &w, int revents);	2287	ev::io io; void io_cb (ev::io &w, int revents);
1762	ev_idle idle void idle_cb (ev::idle &w, int revents);	2288	ev:idle idle void idle_cb (ev::idle &w, int revents);
1763		2289
1764	myclass ();	2290	myclass (int fd)
1765	}
1766
1767	myclass::myclass (int fd)
1768	: io (this, &myclass::io_cb),
1769	idle (this, &myclass::idle_cb)
1770	{	2291	{
		2292	io .set <myclass, &myclass::io_cb > (this);
		2293	idle.set <myclass, &myclass::idle_cb> (this);
		2294
1771	io.start (fd, ev::READ);	2295	io.start (fd, ev::READ);
		2296	}
1772	}	2297	};
1773		2298
1774		2299
1775	=head1 MACRO MAGIC	2300	=head1 MACRO MAGIC
1776		2301
1777	Libev can be compiled with a variety of options, the most fundemantal is	2302	Libev can be compiled with a variety of options, the most fundamantal
1778	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2303	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1779	callbacks have an initial C<struct ev_loop *> argument.	2304	functions and callbacks have an initial C<struct ev_loop *> argument.
1780		2305
1781	To make it easier to write programs that cope with either variant, the	2306	To make it easier to write programs that cope with either variant, the
1782	following macros are defined:	2307	following macros are defined:
1783		2308
1784	=over 4	2309	=over 4
…		…
1816	Similar to the other two macros, this gives you the value of the default	2341	Similar to the other two macros, this gives you the value of the default
1817	loop, if multiple loops are supported ("ev loop default").	2342	loop, if multiple loops are supported ("ev loop default").
1818		2343
1819	=back	2344	=back
1820		2345
1821	Example: Declare and initialise a check watcher, working regardless of	2346	Example: Declare and initialise a check watcher, utilising the above
1822	wether multiple loops are supported or not.	2347	macros so it will work regardless of whether multiple loops are supported
		2348	or not.
1823		2349
1824	static void	2350	static void
1825	check_cb (EV_P_ ev_timer *w, int revents)	2351	check_cb (EV_P_ ev_timer *w, int revents)
1826	{	2352	{
1827	ev_check_stop (EV_A_ w);	2353	ev_check_stop (EV_A_ w);
…		…
1830	ev_check check;	2356	ev_check check;
1831	ev_check_init (&check, check_cb);	2357	ev_check_init (&check, check_cb);
1832	ev_check_start (EV_DEFAULT_ &check);	2358	ev_check_start (EV_DEFAULT_ &check);
1833	ev_loop (EV_DEFAULT_ 0);	2359	ev_loop (EV_DEFAULT_ 0);
1834		2360
1835
1836	=head1 EMBEDDING	2361	=head1 EMBEDDING
1837		2362
1838	Libev can (and often is) directly embedded into host	2363	Libev can (and often is) directly embedded into host
1839	applications. Examples of applications that embed it include the Deliantra	2364	applications. Examples of applications that embed it include the Deliantra
1840	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2365	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1841	and rxvt-unicode.	2366	and rxvt-unicode.
1842		2367
1843	The goal is to enable you to just copy the neecssary files into your	2368	The goal is to enable you to just copy the necessary files into your
1844	source directory without having to change even a single line in them, so	2369	source directory without having to change even a single line in them, so
1845	you can easily upgrade by simply copying (or having a checked-out copy of	2370	you can easily upgrade by simply copying (or having a checked-out copy of
1846	libev somewhere in your source tree).	2371	libev somewhere in your source tree).
1847		2372
1848	=head2 FILESETS	2373	=head2 FILESETS
…		…
1879	ev_vars.h	2404	ev_vars.h
1880	ev_wrap.h	2405	ev_wrap.h
1881		2406
1882	ev_win32.c required on win32 platforms only	2407	ev_win32.c required on win32 platforms only
1883		2408
1884	ev_select.c only when select backend is enabled (which is by default)	2409	ev_select.c only when select backend is enabled (which is enabled by default)
1885	ev_poll.c only when poll backend is enabled (disabled by default)	2410	ev_poll.c only when poll backend is enabled (disabled by default)
1886	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2411	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1887	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2412	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1888	ev_port.c only when the solaris port backend is enabled (disabled by default)	2413	ev_port.c only when the solaris port backend is enabled (disabled by default)
1889		2414
…		…
1938		2463
1939	If defined to be C<1>, libev will try to detect the availability of the	2464	If defined to be C<1>, libev will try to detect the availability of the
1940	monotonic clock option at both compiletime and runtime. Otherwise no use	2465	monotonic clock option at both compiletime and runtime. Otherwise no use
1941	of the monotonic clock option will be attempted. If you enable this, you	2466	of the monotonic clock option will be attempted. If you enable this, you
1942	usually have to link against librt or something similar. Enabling it when	2467	usually have to link against librt or something similar. Enabling it when
1943	the functionality isn't available is safe, though, althoguh you have	2468	the functionality isn't available is safe, though, although you have
1944	to make sure you link against any libraries where the C<clock_gettime>	2469	to make sure you link against any libraries where the C<clock_gettime>
1945	function is hiding in (often F<-lrt>).	2470	function is hiding in (often F<-lrt>).
1946		2471
1947	=item EV_USE_REALTIME	2472	=item EV_USE_REALTIME
1948		2473
1949	If defined to be C<1>, libev will try to detect the availability of the	2474	If defined to be C<1>, libev will try to detect the availability of the
1950	realtime clock option at compiletime (and assume its availability at	2475	realtime clock option at compiletime (and assume its availability at
1951	runtime if successful). Otherwise no use of the realtime clock option will	2476	runtime if successful). Otherwise no use of the realtime clock option will
1952	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2477	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1953	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2478	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1954	in the description of C<EV_USE_MONOTONIC>, though.	2479	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
		2480
		2481	=item EV_USE_NANOSLEEP
		2482
		2483	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
		2484	and will use it for delays. Otherwise it will use C<select ()>.
1955		2485
1956	=item EV_USE_SELECT	2486	=item EV_USE_SELECT
1957		2487
1958	If undefined or defined to be C<1>, libev will compile in support for the	2488	If undefined or defined to be C<1>, libev will compile in support for the
1959	C<select>(2) backend. No attempt at autodetection will be done: if no	2489	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
1977	wants osf handles on win32 (this is the case when the select to	2507	wants osf handles on win32 (this is the case when the select to
1978	be used is the winsock select). This means that it will call	2508	be used is the winsock select). This means that it will call
1979	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	2509	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
1980	it is assumed that all these functions actually work on fds, even	2510	it is assumed that all these functions actually work on fds, even
1981	on win32. Should not be defined on non-win32 platforms.	2511	on win32. Should not be defined on non-win32 platforms.
		2512
		2513	=item EV_FD_TO_WIN32_HANDLE
		2514
		2515	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
		2516	file descriptors to socket handles. When not defining this symbol (the
		2517	default), then libev will call C<_get_osfhandle>, which is usually
		2518	correct. In some cases, programs use their own file descriptor management,
		2519	in which case they can provide this function to map fds to socket handles.
1982		2520
1983	=item EV_USE_POLL	2521	=item EV_USE_POLL
1984		2522
1985	If defined to be C<1>, libev will compile in support for the C<poll>(2)	2523	If defined to be C<1>, libev will compile in support for the C<poll>(2)
1986	backend. Otherwise it will be enabled on non-win32 platforms. It	2524	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
2023	be detected at runtime.	2561	be detected at runtime.
2024		2562
2025	=item EV_H	2563	=item EV_H
2026		2564
2027	The name of the F<ev.h> header file used to include it. The default if	2565	The name of the F<ev.h> header file used to include it. The default if
2028	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2566	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
2029	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2567	used to virtually rename the F<ev.h> header file in case of conflicts.
2030		2568
2031	=item EV_CONFIG_H	2569	=item EV_CONFIG_H
2032		2570
2033	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	2571	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
2034	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	2572	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
2035	C<EV_H>, above.	2573	C<EV_H>, above.
2036		2574
2037	=item EV_EVENT_H	2575	=item EV_EVENT_H
2038		2576
2039	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	2577	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
2040	of how the F<event.h> header can be found.	2578	of how the F<event.h> header can be found, the default is C<"event.h">.
2041		2579
2042	=item EV_PROTOTYPES	2580	=item EV_PROTOTYPES
2043		2581
2044	If defined to be C<0>, then F<ev.h> will not define any function	2582	If defined to be C<0>, then F<ev.h> will not define any function
2045	prototypes, but still define all the structs and other symbols. This is	2583	prototypes, but still define all the structs and other symbols. This is
…		…
2052	will have the C<struct ev_loop *> as first argument, and you can create	2590	will have the C<struct ev_loop *> as first argument, and you can create
2053	additional independent event loops. Otherwise there will be no support	2591	additional independent event loops. Otherwise there will be no support
2054	for multiple event loops and there is no first event loop pointer	2592	for multiple event loops and there is no first event loop pointer
2055	argument. Instead, all functions act on the single default loop.	2593	argument. Instead, all functions act on the single default loop.
2056		2594
		2595	=item EV_MINPRI
		2596
		2597	=item EV_MAXPRI
		2598
		2599	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2600	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2601	provide for more priorities by overriding those symbols (usually defined
		2602	to be C<-2> and C<2>, respectively).
		2603
		2604	When doing priority-based operations, libev usually has to linearly search
		2605	all the priorities, so having many of them (hundreds) uses a lot of space
		2606	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2607	fine.
		2608
		2609	If your embedding app does not need any priorities, defining these both to
		2610	C<0> will save some memory and cpu.
		2611
2057	=item EV_PERIODIC_ENABLE	2612	=item EV_PERIODIC_ENABLE
2058		2613
2059	If undefined or defined to be C<1>, then periodic timers are supported. If	2614	If undefined or defined to be C<1>, then periodic timers are supported. If
		2615	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2616	code.
		2617
		2618	=item EV_IDLE_ENABLE
		2619
		2620	If undefined or defined to be C<1>, then idle watchers are supported. If
2060	defined to be C<0>, then they are not. Disabling them saves a few kB of	2621	defined to be C<0>, then they are not. Disabling them saves a few kB of
2061	code.	2622	code.
2062		2623
2063	=item EV_EMBED_ENABLE	2624	=item EV_EMBED_ENABLE
2064		2625
…		…
2088	than enough. If you need to manage thousands of children you might want to	2649	than enough. If you need to manage thousands of children you might want to
2089	increase this value (I<must> be a power of two).	2650	increase this value (I<must> be a power of two).
2090		2651
2091	=item EV_INOTIFY_HASHSIZE	2652	=item EV_INOTIFY_HASHSIZE
2092		2653
2093	C<ev_staz> watchers use a small hash table to distribute workload by	2654	C<ev_stat> watchers use a small hash table to distribute workload by
2094	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	2655	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2095	usually more than enough. If you need to manage thousands of C<ev_stat>	2656	usually more than enough. If you need to manage thousands of C<ev_stat>
2096	watchers you might want to increase this value (I<must> be a power of	2657	watchers you might want to increase this value (I<must> be a power of
2097	two).	2658	two).
2098		2659
…		…
2115		2676
2116	=item ev_set_cb (ev, cb)	2677	=item ev_set_cb (ev, cb)
2117		2678
2118	Can be used to change the callback member declaration in each watcher,	2679	Can be used to change the callback member declaration in each watcher,
2119	and the way callbacks are invoked and set. Must expand to a struct member	2680	and the way callbacks are invoked and set. Must expand to a struct member
2120	definition and a statement, respectively. See the F<ev.v> header file for	2681	definition and a statement, respectively. See the F<ev.h> header file for
2121	their default definitions. One possible use for overriding these is to	2682	their default definitions. One possible use for overriding these is to
2122	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2683	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2123	method calls instead of plain function calls in C++.	2684	method calls instead of plain function calls in C++.
		2685
		2686	=head2 EXPORTED API SYMBOLS
		2687
		2688	If you need to re-export the API (e.g. via a dll) and you need a list of
		2689	exported symbols, you can use the provided F<Symbol.*> files which list
		2690	all public symbols, one per line:
		2691
		2692	Symbols.ev for libev proper
		2693	Symbols.event for the libevent emulation
		2694
		2695	This can also be used to rename all public symbols to avoid clashes with
		2696	multiple versions of libev linked together (which is obviously bad in
		2697	itself, but sometimes it is inconvinient to avoid this).
		2698
		2699	A sed command like this will create wrapper C<#define>'s that you need to
		2700	include before including F<ev.h>:
		2701
		2702	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2703
		2704	This would create a file F<wrap.h> which essentially looks like this:
		2705
		2706	#define ev_backend myprefix_ev_backend
		2707	#define ev_check_start myprefix_ev_check_start
		2708	#define ev_check_stop myprefix_ev_check_stop
		2709	...
2124		2710
2125	=head2 EXAMPLES	2711	=head2 EXAMPLES
2126		2712
2127	For a real-world example of a program the includes libev	2713	For a real-world example of a program the includes libev
2128	verbatim, you can have a look at the EV perl module	2714	verbatim, you can have a look at the EV perl module
…		…
2131	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2717	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2132	will be compiled. It is pretty complex because it provides its own header	2718	will be compiled. It is pretty complex because it provides its own header
2133	file.	2719	file.
2134		2720
2135	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2721	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2136	that everybody includes and which overrides some autoconf choices:	2722	that everybody includes and which overrides some configure choices:
2137		2723
		2724	#define EV_MINIMAL 1
2138	#define EV_USE_POLL 0	2725	#define EV_USE_POLL 0
2139	#define EV_MULTIPLICITY 0	2726	#define EV_MULTIPLICITY 0
2140	#define EV_PERIODICS 0	2727	#define EV_PERIODIC_ENABLE 0
		2728	#define EV_STAT_ENABLE 0
		2729	#define EV_FORK_ENABLE 0
2141	#define EV_CONFIG_H <config.h>	2730	#define EV_CONFIG_H <config.h>
		2731	#define EV_MINPRI 0
		2732	#define EV_MAXPRI 0
2142		2733
2143	#include "ev++.h"	2734	#include "ev++.h"
2144		2735
2145	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2736	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2146		2737
…		…
2152		2743
2153	In this section the complexities of (many of) the algorithms used inside	2744	In this section the complexities of (many of) the algorithms used inside
2154	libev will be explained. For complexity discussions about backends see the	2745	libev will be explained. For complexity discussions about backends see the
2155	documentation for C<ev_default_init>.	2746	documentation for C<ev_default_init>.
2156		2747
		2748	All of the following are about amortised time: If an array needs to be
		2749	extended, libev needs to realloc and move the whole array, but this
		2750	happens asymptotically never with higher number of elements, so O(1) might
		2751	mean it might do a lengthy realloc operation in rare cases, but on average
		2752	it is much faster and asymptotically approaches constant time.
		2753
2157	=over 4	2754	=over 4
2158		2755
2159	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2756	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2160		2757
		2758	This means that, when you have a watcher that triggers in one hour and
		2759	there are 100 watchers that would trigger before that then inserting will
		2760	have to skip roughly seven (C<ld 100>) of these watchers.
		2761
2161	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2762	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
		2763
		2764	That means that changing a timer costs less than removing/adding them
		2765	as only the relative motion in the event queue has to be paid for.
2162		2766
2163	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2767	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2164		2768
		2769	These just add the watcher into an array or at the head of a list.
		2770
2165	=item Stopping check/prepare/idle watchers: O(1)	2771	=item Stopping check/prepare/idle watchers: O(1)
2166		2772
2167	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2773	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2168		2774
		2775	These watchers are stored in lists then need to be walked to find the
		2776	correct watcher to remove. The lists are usually short (you don't usually
		2777	have many watchers waiting for the same fd or signal).
		2778
2169	=item Finding the next timer per loop iteration: O(1)	2779	=item Finding the next timer in each loop iteration: O(1)
		2780
		2781	By virtue of using a binary heap, the next timer is always found at the
		2782	beginning of the storage array.
2170		2783
2171	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2784	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2172		2785
2173	=item Activating one watcher: O(1)	2786	A change means an I/O watcher gets started or stopped, which requires
		2787	libev to recalculate its status (and possibly tell the kernel, depending
		2788	on backend and wether C<ev_io_set> was used).
		2789
		2790	=item Activating one watcher (putting it into the pending state): O(1)
		2791
		2792	=item Priority handling: O(number_of_priorities)
		2793
		2794	Priorities are implemented by allocating some space for each
		2795	priority. When doing priority-based operations, libev usually has to
		2796	linearly search all the priorities, but starting/stopping and activating
		2797	watchers becomes O(1) w.r.t. prioritiy handling.
2174		2798
2175	=back	2799	=back
2176		2800
2177		2801
		2802	=head1 Win32 platform limitations and workarounds
		2803
		2804	Win32 doesn't support any of the standards (e.g. POSIX) that libev
		2805	requires, and its I/O model is fundamentally incompatible with the POSIX
		2806	model. Libev still offers limited functionality on this platform in
		2807	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
		2808	descriptors. This only applies when using Win32 natively, not when using
		2809	e.g. cygwin.
		2810
		2811	There is no supported compilation method available on windows except
		2812	embedding it into other applications.
		2813
		2814	Due to the many, low, and arbitrary limits on the win32 platform and the
		2815	abysmal performance of winsockets, using a large number of sockets is not
		2816	recommended (and not reasonable). If your program needs to use more than
		2817	a hundred or so sockets, then likely it needs to use a totally different
		2818	implementation for windows, as libev offers the POSIX model, which cannot
		2819	be implemented efficiently on windows (microsoft monopoly games).
		2820
		2821	=over 4
		2822
		2823	=item The winsocket select function
		2824
		2825	The winsocket C<select> function doesn't follow POSIX in that it requires
		2826	socket I<handles> and not socket I<file descriptors>. This makes select
		2827	very inefficient, and also requires a mapping from file descriptors
		2828	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,
		2829	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor
		2830	symbols for more info.
		2831
		2832	The configuration for a "naked" win32 using the microsoft runtime
		2833	libraries and raw winsocket select is:
		2834
		2835	#define EV_USE_SELECT 1
		2836	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
		2837
		2838	Note that winsockets handling of fd sets is O(n), so you can easily get a
		2839	complexity in the O(n²) range when using win32.
		2840
		2841	=item Limited number of file descriptors
		2842
		2843	Windows has numerous arbitrary (and low) limits on things. Early versions
		2844	of winsocket's select only supported waiting for a max. of C<64> handles
		2845	(probably owning to the fact that all windows kernels can only wait for
		2846	C<64> things at the same time internally; microsoft recommends spawning a
		2847	chain of threads and wait for 63 handles and the previous thread in each).
		2848
		2849	Newer versions support more handles, but you need to define C<FD_SETSIZE>
		2850	to some high number (e.g. C<2048>) before compiling the winsocket select
		2851	call (which might be in libev or elsewhere, for example, perl does its own
		2852	select emulation on windows).
		2853
		2854	Another limit is the number of file descriptors in the microsoft runtime
		2855	libraries, which by default is C<64> (there must be a hidden I<64> fetish
		2856	or something like this inside microsoft). You can increase this by calling
		2857	C<_setmaxstdio>, which can increase this limit to C<2048> (another
		2858	arbitrary limit), but is broken in many versions of the microsoft runtime
		2859	libraries.
		2860
		2861	This might get you to about C<512> or C<2048> sockets (depending on
		2862	windows version and/or the phase of the moon). To get more, you need to
		2863	wrap all I/O functions and provide your own fd management, but the cost of
		2864	calling select (O(n²)) will likely make this unworkable.
		2865
		2866	=back
		2867
		2868
2178	=head1 AUTHOR	2869	=head1 AUTHOR
2179		2870
2180	Marc Lehmann <libev@schmorp.de>.	2871	Marc Lehmann <libev@schmorp.de>.
2181		2872

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