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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>), the Linux C<inotify> interface	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
71	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers	75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
…		…
78		82
79	It also is quite fast (see this	83	It also is quite fast (see this
80	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
81	for example).	85	for example).
82		86
83	=head1 CONVENTIONS	87	=head2 CONVENTIONS
84		88
85	Libev is very configurable. In this manual the default configuration will	89	Libev is very configurable. In this manual the default configuration will
86	be described, which supports multiple event loops. For more info about	90	be described, which supports multiple event loops. For more info about
87	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
88	this manual. If libev was configured without support for multiple event	92	this manual. If libev was configured without support for multiple event
89	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>
90	(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.
91		95
92	=head1 TIME REPRESENTATION	96	=head2 TIME REPRESENTATION
93		97
94	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
95	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
96	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
97	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
98	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
99	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.
100		106
101	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
102		108
103	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
104	library in any way.	110	library in any way.
…		…
109		115
110	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
111	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
112	you actually want to know.	118	you actually want to know.
113		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
114	=item int ev_version_major ()	126	=item int ev_version_major ()
115		127
116	=item int ev_version_minor ()	128	=item int ev_version_minor ()
117		129
118	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
119	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
120	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
121	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
122	version of the library your program was compiled against.	134	version of the library your program was compiled against.
123		135
		136	These version numbers refer to the ABI version of the library, not the
		137	release version.
		138
124	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,
125	as this indicates an incompatible change. Minor versions are usually	140	as this indicates an incompatible change. Minor versions are usually
126	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
127	not a problem.	142	not a problem.
128		143
129	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
130	version.	145	version.
…		…
245	flags. If that is troubling you, check C<ev_backend ()> afterwards).	260	flags. If that is troubling you, check C<ev_backend ()> afterwards).
246		261
247	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
248	function.	263	function.
249		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
250	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
251	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>).
252		274
253	The following flags are supported:	275	The following flags are supported:
254		276
…		…
266	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	288	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
267	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
268	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
269	around bugs.	291	around bugs.
270		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
271	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	313	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
272		314
273	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
274	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,
275	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
276	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
277	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.
278		327
279	=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)
280		329
281	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
282	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
283	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
284	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.
285		336
286	=item C<EVBACKEND_EPOLL> (value 4, Linux)	337	=item C<EVBACKEND_EPOLL> (value 4, Linux)
287		338
288	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,
289	but it scales phenomenally better. While poll and select usually scale like	340	but it scales phenomenally better. While poll and select usually scale
290	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),
291	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.
292		346
293	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
294	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
295	(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
296	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
297	well if you register events for both fds.	351	very well if you register events for both fds.
298		352
299	Please note that epoll sometimes generates spurious notifications, so you	353	Please note that epoll sometimes generates spurious notifications, so you
300	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
301	(or space) is available.	355	(or space) is available.
302		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
303	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	364	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
304		365
305	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
306	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
307	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
308	completely useless). For this reason its not being "autodetected"	369	it's completely useless). For this reason it's not being "autodetected"
309	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
310	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.
311		377
312	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
313	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
314	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
315	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
316	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.
317		393
318	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	394	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
319		395
320	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.
321		400
322	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	401	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
323		402
324	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,
325	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)).
326		405
327	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
328	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
329	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.
330		418
331	=item C<EVBACKEND_ALL>	419	=item C<EVBACKEND_ALL>
332		420
333	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
334	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
335	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	423	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
336		424
		425	It is definitely not recommended to use this flag.
		426
337	=back	427	=back
338		428
339	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
340	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
341	specified, most compiled-in backend will be tried, usually in reverse	431	specified, all backends in C<ev_recommended_backends ()> will be tried.
342	order of their flag values :)
343		432
344	The most typical usage is like this:	433	The most typical usage is like this:
345		434
346	if (!ev_default_loop (0))	435	if (!ev_default_loop (0))
347	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	436	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
…		…
375	Destroys the default loop again (frees all memory and kernel state	464	Destroys the default loop again (frees all memory and kernel state
376	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
377	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
378	responsibility to either stop all watchers cleanly yoursef I<before>	467	responsibility to either stop all watchers cleanly yoursef I<before>
379	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
380	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
381	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>).
382		480
383	=item ev_loop_destroy (loop)	481	=item ev_loop_destroy (loop)
384		482
385	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
386	earlier call to C<ev_loop_new>.	484	earlier call to C<ev_loop_new>.
387		485
388	=item ev_default_fork ()	486	=item ev_default_fork ()
389		487
		488	This function sets a flag that causes subsequent C<ev_loop> iterations
390	This function reinitialises the kernel state for backends that have	489	to reinitialise the kernel state for backends that have one. Despite the
391	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
392	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
393	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.
394		494
395	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
396	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
397	fork+exec, you don't have to call it.	497	you just fork+exec, you don't have to call it at all.
398		498
399	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
400	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
401	quite nicely into a call to C<pthread_atfork>:	501	quite nicely into a call to C<pthread_atfork>:
402		502
403	pthread_atfork (0, 0, ev_default_fork);	503	pthread_atfork (0, 0, ev_default_fork);
404		504
405	At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use
406	without calling this function, so if you force one of those backends you
407	do not need to care.
408
409	=item ev_loop_fork (loop)	505	=item ev_loop_fork (loop)
410		506
411	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
412	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
413	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.
414		520
415	=item unsigned int ev_backend (loop)	521	=item unsigned int ev_backend (loop)
416		522
417	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
418	use.	524	use.
…		…
421		527
422	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
423	received events and started processing them. This timestamp does not	529	received events and started processing them. This timestamp does not
424	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
425	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
426	event occuring (or more correctly, libev finding out about it).	532	event occurring (or more correctly, libev finding out about it).
427		533
428	=item ev_loop (loop, int flags)	534	=item ev_loop (loop, int flags)
429		535
430	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
431	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
…		…
452	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
453	usually a better approach for this kind of thing.	559	usually a better approach for this kind of thing.
454		560
455	Here are the gory details of what C<ev_loop> does:	561	Here are the gory details of what C<ev_loop> does:
456		562
457	* If there are no active watchers (reference count is zero), return.	563	- Before the first iteration, call any pending watchers.
458	- 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.
459	- If we have been forked, recreate the kernel state.	567	- If we have been forked, recreate the kernel state.
460	- Update the kernel state with all outstanding changes.	568	- Update the kernel state with all outstanding changes.
461	- Update the "event loop time".	569	- Update the "event loop time".
462	- 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.
463	- Block the process, waiting for any events.	574	- Block the process, waiting for any events.
464	- Queue all outstanding I/O (fd) events.	575	- Queue all outstanding I/O (fd) events.
465	- Update the "event loop time" and do time jump handling.	576	- Update the "event loop time" and do time jump handling.
466	- Queue all outstanding timers.	577	- Queue all outstanding timers.
467	- Queue all outstanding periodics.	578	- Queue all outstanding periodics.
468	- If no events are pending now, queue all idle watchers.	579	- If no events are pending now, queue all idle watchers.
469	- Queue all check watchers.	580	- Queue all check watchers.
470	- 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).
471	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
472	be handled here by queueing them when their watcher gets executed.	583	be handled here by queueing them when their watcher gets executed.
473	- 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
474	were used, return, otherwise continue with step *.	585	were used, or there are no active watchers, return, otherwise
		586	continue with step *.
475		587
476	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
477	anymore.	589	anymore.
478		590
479	... queue jobs here, make sure they register event watchers as long	591	... queue jobs here, make sure they register event watchers as long
480	... 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..)
481	ev_loop (my_loop, 0);	593	ev_loop (my_loop, 0);
…		…
485		597
486	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
487	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
488	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
489	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.
490		604
491	=item ev_ref (loop)	605	=item ev_ref (loop)
492		606
493	=item ev_unref (loop)	607	=item ev_unref (loop)
494		608
…		…
499	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
500	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
501	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
502	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
503	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
504	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).
505		621
506	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>
507	running when nothing else is active.	623	running when nothing else is active.
508		624
509	struct ev_signal exitsig;	625	struct ev_signal exitsig;
…		…
513		629
514	Example: For some weird reason, unregister the above signal handler again.	630	Example: For some weird reason, unregister the above signal handler again.
515		631
516	ev_ref (loop);	632	ev_ref (loop);
517	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.
518		670
519	=back	671	=back
520		672
521		673
522	=head1 ANATOMY OF A WATCHER	674	=head1 ANATOMY OF A WATCHER
…		…
702	=item bool ev_is_pending (ev_TYPE *watcher)	854	=item bool ev_is_pending (ev_TYPE *watcher)
703		855
704	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
705	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
706	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
707	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
708	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).
709		862
710	=item callback ev_cb (ev_TYPE *watcher)	863	=item callback ev_cb (ev_TYPE *watcher)
711		864
712	Returns the callback currently set on the watcher.	865	Returns the callback currently set on the watcher.
713		866
714	=item ev_cb_set (ev_TYPE *watcher, callback)	867	=item ev_cb_set (ev_TYPE *watcher, callback)
715		868
716	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
717	(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>.
718		911
719	=back	912	=back
720		913
721		914
722	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	915	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
807	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
808	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
809	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
810	required if you know what you are doing).	1003	required if you know what you are doing).
811		1004
812	You have to be careful with dup'ed file descriptors, though. Some backends
813	(the linux epoll backend is a notable example) cannot handle dup'ed file
814	descriptors correctly if you register interest in two or more fds pointing
815	to the same underlying file/socket/etc. description (that is, they share
816	the same underlying "file open").
817
818	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
819	(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
820	C<EVBACKEND_POLL>).	1007	C<EVBACKEND_POLL>).
821		1008
822	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
…		…
828	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
829	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.
830		1017
831	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
832	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
833	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
834	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
835	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
836		1069
837	=over 4	1070	=over 4
838		1071
839	=item ev_io_init (ev_io *, callback, int fd, int events)	1072	=item ev_io_init (ev_io *, callback, int fd, int events)
840		1073
…		…
851	=item int events [read-only]	1084	=item int events [read-only]
852		1085
853	The events being watched.	1086	The events being watched.
854		1087
855	=back	1088	=back
		1089
		1090	=head3 Examples
856		1091
857	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
858	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
859	attempt to read a whole line in the callback.	1094	attempt to read a whole line in the callback.
860		1095
…		…
893	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1128	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
894		1129
895	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,
896	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
897	order of execution is undefined.	1132	order of execution is undefined.
		1133
		1134	=head3 Watcher-Specific Functions and Data Members
898		1135
899	=over 4	1136	=over 4
900		1137
901	=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)
902		1139
…		…
956	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),
957	which is also when any modifications are taken into account.	1194	which is also when any modifications are taken into account.
958		1195
959	=back	1196	=back
960		1197
		1198	=head3 Examples
		1199
961	Example: Create a timer that fires after 60 seconds.	1200	Example: Create a timer that fires after 60 seconds.
962		1201
963	static void	1202	static void
964	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)
965	{	1204	{
…		…
998	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
999	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
1000	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 ()
1001	+ 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
1002	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
1003	roughly 10 seconds later and of course not if you reset your system time	1242	roughly 10 seconds later).
1004	again).
1005		1243
1006	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
1007	triggering an event on eahc midnight, local time.	1245	triggering an event on each midnight, local time or other, complicated,
		1246	rules.
1008		1247
1009	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
1010	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
1011	during the same loop iteration then order of execution is undefined.	1250	during the same loop iteration then order of execution is undefined.
1012		1251
		1252	=head3 Watcher-Specific Functions and Data Members
		1253
1013	=over 4	1254	=over 4
1014		1255
1015	=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)
1016		1257
1017	=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)
…		…
1019	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
1020	operation, and we will explain them from simplest to complex:	1261	operation, and we will explain them from simplest to complex:
1021		1262
1022	=over 4	1263	=over 4
1023		1264
1024	=item * absolute timer (interval = reschedule_cb = 0)	1265	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1025		1266
1026	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
1027	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,
1028	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
1029	system time reaches or surpasses this time.	1270	system time reaches or surpasses this time.
1030		1271
1031	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1272	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1032		1273
1033	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
1034	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)
1035	of any time jumps.	1276	and then repeat, regardless of any time jumps.
1036		1277
1037	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
1038	time:	1279	time:
1039		1280
1040	ev_periodic_set (&periodic, 0., 3600., 0);	1281	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1046		1287
1047	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
1048	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
1049	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.
1050		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
1051	=item * manual reschedule mode (reschedule_cb = callback)	1296	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1052		1297
1053	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
1054	ignored. Instead, each time the periodic watcher gets scheduled, the	1299	ignored. Instead, each time the periodic watcher gets scheduled, the
1055	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
1056	current time as second argument.	1301	current time as second argument.
1057		1302
1058	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,
1059	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,
1060	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
1061	starting a prepare watcher).	1306	starting an C<ev_prepare> watcher, which is legal).
1062		1307
1063	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,
1064	ev_tstamp now)>, e.g.:	1309	ev_tstamp now)>, e.g.:
1065		1310
1066	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)
…		…
1089	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
1090	when you changed some parameters or the reschedule callback would return	1335	when you changed some parameters or the reschedule callback would return
1091	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
1092	program when the crontabs have changed).	1337	program when the crontabs have changed).
1093		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
1094	=item ev_tstamp interval [read-write]	1347	=item ev_tstamp interval [read-write]
1095		1348
1096	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
1097	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
1098	called.	1351	called.
…		…
1101		1354
1102	The current reschedule callback, or C<0>, if this functionality is	1355	The current reschedule callback, or C<0>, if this functionality is
1103	switched off. Can be changed any time, but changes only take effect when	1356	switched off. Can be changed any time, but changes only take effect when
1104	the periodic timer fires or C<ev_periodic_again> is being called.	1357	the periodic timer fires or C<ev_periodic_again> is being called.
1105		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
1106	=back	1364	=back
		1365
		1366	=head3 Examples
1107		1367
1108	Example: Call a callback every hour, or, more precisely, whenever the	1368	Example: Call a callback every hour, or, more precisely, whenever the
1109	system clock is divisible by 3600. The callback invocation times have	1369	system clock is divisible by 3600. The callback invocation times have
1110	potentially a lot of jittering, but good long-term stability.	1370	potentially a lot of jittering, but good long-term stability.
1111		1371
…		…
1151	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
1152	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
1153	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
1154	SIG_DFL (regardless of what it was set to before).	1414	SIG_DFL (regardless of what it was set to before).
1155		1415
		1416	=head3 Watcher-Specific Functions and Data Members
		1417
1156	=over 4	1418	=over 4
1157		1419
1158	=item ev_signal_init (ev_signal *, callback, int signum)	1420	=item ev_signal_init (ev_signal *, callback, int signum)
1159		1421
1160	=item ev_signal_set (ev_signal *, int signum)	1422	=item ev_signal_set (ev_signal *, int signum)
…		…
1172	=head2 C<ev_child> - watch out for process status changes	1434	=head2 C<ev_child> - watch out for process status changes
1173		1435
1174	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
1175	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).
1176		1438
		1439	=head3 Watcher-Specific Functions and Data Members
		1440
1177	=over 4	1441	=over 4
1178		1442
1179	=item ev_child_init (ev_child *, callback, int pid)	1443	=item ev_child_init (ev_child *, callback, int pid, int trace)
1180		1444
1181	=item ev_child_set (ev_child *, int pid)	1445	=item ev_child_set (ev_child *, int pid, int trace)
1182		1446
1183	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
1184	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
1185	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
1186	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
1187	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
1188	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).
1189		1455
1190	=item int pid [read-only]	1456	=item int pid [read-only]
1191		1457
1192	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.
1193		1459
…		…
1199		1465
1200	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
1201	C<waitpid> and C<sys/wait.h> documentation for details).	1467	C<waitpid> and C<sys/wait.h> documentation for details).
1202		1468
1203	=back	1469	=back
		1470
		1471	=head3 Examples
1204		1472
1205	Example: Try to exit cleanly on SIGINT and SIGTERM.	1473	Example: Try to exit cleanly on SIGINT and SIGTERM.
1206		1474
1207	static void	1475	static void
1208	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)
…		…
1249	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1517	semantics of C<ev_stat> watchers, which means that libev sometimes needs
1250	to fall back to regular polling again even with inotify, but changes are	1518	to fall back to regular polling again even with inotify, but changes are
1251	usually detected immediately, and if the file exists there will be no	1519	usually detected immediately, and if the file exists there will be no
1252	polling.	1520	polling.
1253		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
		1556
1254	=over 4	1557	=over 4
1255		1558
1256	=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)
1257		1560
1258	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)	1561	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)
…		…
1293	=item const char *path [read-only]	1596	=item const char *path [read-only]
1294		1597
1295	The filesystem path that is being watched.	1598	The filesystem path that is being watched.
1296		1599
1297	=back	1600	=back
		1601
		1602	=head3 Examples
1298		1603
1299	Example: Watch C</etc/passwd> for attribute changes.	1604	Example: Watch C</etc/passwd> for attribute changes.
1300		1605
1301	static void	1606	static void
1302	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1607	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
…		…
1315	}	1620	}
1316		1621
1317	...	1622	...
1318	ev_stat passwd;	1623	ev_stat passwd;
1319		1624
1320	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");	1625	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1321	ev_stat_start (loop, &passwd);	1626	ev_stat_start (loop, &passwd);
1322		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
1323		1656
1324	=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...
1325		1658
1326	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
1327	(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
1328	as your process is busy handling sockets or timeouts (or even signals,	1661	count).
1329	imagine) it will not be triggered. But when your process is idle all idle	1662
1330	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
1331	until stopped, that is, or your process receives more events and becomes	1667	iteration - until stopped, that is, or your process receives more events
1332	busy.	1668	and becomes busy again with higher priority stuff.
1333		1669
1334	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
1335	active, the process will not block when waiting for new events.	1671	active, the process will not block when waiting for new events.
1336		1672
1337	Apart from keeping your process non-blocking (which is a useful	1673	Apart from keeping your process non-blocking (which is a useful
1338	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
1339	"pseudo-background processing", or delay processing stuff to after the	1675	"pseudo-background processing", or delay processing stuff to after the
1340	event loop has handled all outstanding events.	1676	event loop has handled all outstanding events.
1341		1677
		1678	=head3 Watcher-Specific Functions and Data Members
		1679
1342	=over 4	1680	=over 4
1343		1681
1344	=item ev_idle_init (ev_signal *, callback)	1682	=item ev_idle_init (ev_signal *, callback)
1345		1683
1346	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
1347	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,
1348	believe me.	1686	believe me.
1349		1687
1350	=back	1688	=back
		1689
		1690	=head3 Examples
1351		1691
1352	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
1353	callback, free it. Also, use no error checking, as usual.	1693	callback, free it. Also, use no error checking, as usual.
1354		1694
1355	static void	1695	static void
…		…
1403	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
1404	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
1405	loop from blocking if lower-priority coroutines are active, thus mapping	1745	loop from blocking if lower-priority coroutines are active, thus mapping
1406	low-priority coroutines to idle/background tasks).	1746	low-priority coroutines to idle/background tasks).
1407		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
1408	=over 4	1760	=over 4
1409		1761
1410	=item ev_prepare_init (ev_prepare *, callback)	1762	=item ev_prepare_init (ev_prepare *, callback)
1411		1763
1412	=item ev_check_init (ev_check *, callback)	1764	=item ev_check_init (ev_check *, callback)
…		…
1415	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>
1416	macros, but using them is utterly, utterly and completely pointless.	1768	macros, but using them is utterly, utterly and completely pointless.
1417		1769
1418	=back	1770	=back
1419		1771
1420	Example: To include a library such as adns, you would add IO watchers	1772	=head3 Examples
1421	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,
1422	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
1423	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.
1424		1786
1425	static ev_io iow [nfd];	1787	static ev_io iow [nfd];
1426	static ev_timer tw;	1788	static ev_timer tw;
1427		1789
1428	static void	1790	static void
1429	io_cb (ev_loop *loop, ev_io *w, int revents)	1791	io_cb (ev_loop *loop, ev_io *w, int revents)
1430	{	1792	{
1431	// set the relevant poll flags
1432	// could also call adns_processreadable etc. here
1433	struct pollfd *fd = (struct pollfd *)w->data;
1434	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1435	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1436	}	1793	}
1437		1794
1438	// create io watchers for each fd and a timer before blocking	1795	// create io watchers for each fd and a timer before blocking
1439	static void	1796	static void
1440	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1797	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1441	{	1798	{
1442	int timeout = 3600000;truct pollfd fds [nfd];	1799	int timeout = 3600000;
		1800	struct pollfd fds [nfd];
1443	// actual code will need to loop here and realloc etc.	1801	// actual code will need to loop here and realloc etc.
1444	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1802	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1445		1803
1446	/* 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 */
1447	ev_timer_init (&tw, 0, timeout * 1e-3);	1805	ev_timer_init (&tw, 0, timeout * 1e-3);
1448	ev_timer_start (loop, &tw);	1806	ev_timer_start (loop, &tw);
1449		1807
1450	// create on ev_io per pollfd	1808	// create one ev_io per pollfd
1451	for (int i = 0; i < nfd; ++i)	1809	for (int i = 0; i < nfd; ++i)
1452	{	1810	{
1453	ev_io_init (iow + i, io_cb, fds [i].fd,	1811	ev_io_init (iow + i, io_cb, fds [i].fd,
1454	((fds [i].events & POLLIN ? EV_READ : 0)	1812	((fds [i].events & POLLIN ? EV_READ : 0)
1455	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1813	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1456		1814
1457	fds [i].revents = 0;	1815	fds [i].revents = 0;
1458	iow [i].data = fds + i;
1459	ev_io_start (loop, iow + i);	1816	ev_io_start (loop, iow + i);
1460	}	1817	}
1461	}	1818	}
1462		1819
1463	// stop all watchers after blocking	1820	// stop all watchers after blocking
…		…
1465	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1822	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1466	{	1823	{
1467	ev_timer_stop (loop, &tw);	1824	ev_timer_stop (loop, &tw);
1468		1825
1469	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
1470	ev_io_stop (loop, iow + i);	1836	ev_io_stop (loop, iow + i);
		1837	}
1471		1838
1472	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;
1473	}	1899	}
1474		1900
1475		1901
1476	=head2 C<ev_embed> - when one backend isn't enough...	1902	=head2 C<ev_embed> - when one backend isn't enough...
1477		1903
…		…
1520	portable one.	1946	portable one.
1521		1947
1522	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
1523	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
1524	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
1525	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).
1526		1986
1527	struct ev_loop *loop_hi = ev_default_init (0);	1987	struct ev_loop *loop_hi = ev_default_init (0);
1528	struct ev_loop *loop_lo = 0;	1988	struct ev_loop *loop_lo = 0;
1529	struct ev_embed embed;	1989	struct ev_embed embed;
1530		1990
…		…
1541	ev_embed_start (loop_hi, &embed);	2001	ev_embed_start (loop_hi, &embed);
1542	}	2002	}
1543	else	2003	else
1544	loop_lo = loop_hi;	2004	loop_lo = loop_hi;
1545		2005
1546	=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).
1547		2010
1548	=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	}
1549		2021
1550	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	2022	if (!loop_socket)
		2023	loop_socket = loop;
1551		2024
1552	Configures the watcher to embed the given loop, which must be	2025	// now use loop_socket for all sockets, and loop for everything else
1553	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
1554	invoked automatically, otherwise it is the responsibility of the callback
1555	to invoke it (it will continue to be called until the sweep has been done,
1556	if you do not want thta, you need to temporarily stop the embed watcher).
1557
1558	=item ev_embed_sweep (loop, ev_embed *)
1559
1560	Make a single, non-blocking sweep over the embedded loop. This works
1561	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1562	apropriate way for embedded loops.
1563
1564	=item struct ev_loop *loop [read-only]
1565
1566	The embedded event loop.
1567
1568	=back
1569		2026
1570		2027
1571	=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
1572		2029
1573	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
…		…
1576	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,
1577	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
1578	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
1579	handlers will be invoked, too, of course.	2036	handlers will be invoked, too, of course.
1580		2037
		2038	=head3 Watcher-Specific Functions and Data Members
		2039
1581	=over 4	2040	=over 4
1582		2041
1583	=item ev_fork_init (ev_signal *, callback)	2042	=item ev_fork_init (ev_signal *, callback)
1584		2043
1585	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
…		…
1681		2140
1682	To use it,	2141	To use it,
1683		2142
1684	#include <ev++.h>	2143	#include <ev++.h>
1685		2144
1686	(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
1687	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
1688	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>.
1689		2149
1690	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++
1691	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).
1692		2160
1693	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:
1694		2162
1695	=over 4	2163	=over 4
1696		2164
…		…
1712		2180
1713	All of those classes have these methods:	2181	All of those classes have these methods:
1714		2182
1715	=over 4	2183	=over 4
1716		2184
1717	=item ev::TYPE::TYPE (object *, object::method *)	2185	=item ev::TYPE::TYPE ()
1718		2186
1719	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)	2187	=item ev::TYPE::TYPE (struct ev_loop *)
1720		2188
1721	=item ev::TYPE::~TYPE	2189	=item ev::TYPE::~TYPE
1722		2190
1723	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
1724	the event handler callback to call in this class. The constructor calls	2192	with. If it is omitted, it will use C<EV_DEFAULT>.
1725	C<ev_init> for you, which means you have to call the C<set> method	2193
1726	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
1727	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).
1728		2202
1729	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> ();
1730		2243
1731	=item w->set (struct ev_loop *)	2244	=item w->set (struct ev_loop *)
1732		2245
1733	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
1734	do this when the watcher is inactive (and not pending either).	2247	do this when the watcher is inactive (and not pending either).
1735		2248
1736	=item w->set ([args])	2249	=item w->set ([args])
1737		2250
1738	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
1739	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
1740	automatically stopped and restarted.	2253	automatically stopped and restarted when reconfiguring it with this
		2254	method.
1741		2255
1742	=item w->start ()	2256	=item w->start ()
1743		2257
1744	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
1745	constructor already takes the loop.	2259	constructor already stores the event loop.
1746		2260
1747	=item w->stop ()	2261	=item w->stop ()
1748		2262
1749	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.
1750		2264
1751	=item w->again () C<ev::timer>, C<ev::periodic> only	2265	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1752		2266
1753	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
1754	C<ev_TYPE_again> function.	2268	C<ev_TYPE_again> function.
1755		2269
1756	=item w->sweep () C<ev::embed> only	2270	=item w->sweep () (C<ev::embed> only)
1757		2271
1758	Invokes C<ev_embed_sweep>.	2272	Invokes C<ev_embed_sweep>.
1759		2273
1760	=item w->update () C<ev::stat> only	2274	=item w->update () (C<ev::stat> only)
1761		2275
1762	Invokes C<ev_stat_stat>.	2276	Invokes C<ev_stat_stat>.
1763		2277
1764	=back	2278	=back
1765		2279
…		…
1775		2289
1776	myclass ();	2290	myclass ();
1777	}	2291	}
1778		2292
1779	myclass::myclass (int fd)	2293	myclass::myclass (int fd)
1780	: io (this, &myclass::io_cb),
1781	idle (this, &myclass::idle_cb)
1782	{	2294	{
		2295	io .set <myclass, &myclass::io_cb > (this);
		2296	idle.set <myclass, &myclass::idle_cb> (this);
		2297
1783	io.start (fd, ev::READ);	2298	io.start (fd, ev::READ);
1784	}	2299	}
1785		2300
1786		2301
1787	=head1 MACRO MAGIC	2302	=head1 MACRO MAGIC
1788		2303
1789	Libev can be compiled with a variety of options, the most fundemantal is	2304	Libev can be compiled with a variety of options, the most fundamantal
1790	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2305	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1791	callbacks have an initial C<struct ev_loop *> argument.	2306	functions and callbacks have an initial C<struct ev_loop *> argument.
1792		2307
1793	To make it easier to write programs that cope with either variant, the	2308	To make it easier to write programs that cope with either variant, the
1794	following macros are defined:	2309	following macros are defined:
1795		2310
1796	=over 4	2311	=over 4
…		…
1828	Similar to the other two macros, this gives you the value of the default	2343	Similar to the other two macros, this gives you the value of the default
1829	loop, if multiple loops are supported ("ev loop default").	2344	loop, if multiple loops are supported ("ev loop default").
1830		2345
1831	=back	2346	=back
1832		2347
1833	Example: Declare and initialise a check watcher, working regardless of	2348	Example: Declare and initialise a check watcher, utilising the above
1834	wether multiple loops are supported or not.	2349	macros so it will work regardless of whether multiple loops are supported
		2350	or not.
1835		2351
1836	static void	2352	static void
1837	check_cb (EV_P_ ev_timer *w, int revents)	2353	check_cb (EV_P_ ev_timer *w, int revents)
1838	{	2354	{
1839	ev_check_stop (EV_A_ w);	2355	ev_check_stop (EV_A_ w);
…		…
1842	ev_check check;	2358	ev_check check;
1843	ev_check_init (&check, check_cb);	2359	ev_check_init (&check, check_cb);
1844	ev_check_start (EV_DEFAULT_ &check);	2360	ev_check_start (EV_DEFAULT_ &check);
1845	ev_loop (EV_DEFAULT_ 0);	2361	ev_loop (EV_DEFAULT_ 0);
1846		2362
1847
1848	=head1 EMBEDDING	2363	=head1 EMBEDDING
1849		2364
1850	Libev can (and often is) directly embedded into host	2365	Libev can (and often is) directly embedded into host
1851	applications. Examples of applications that embed it include the Deliantra	2366	applications. Examples of applications that embed it include the Deliantra
1852	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2367	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1853	and rxvt-unicode.	2368	and rxvt-unicode.
1854		2369
1855	The goal is to enable you to just copy the neecssary files into your	2370	The goal is to enable you to just copy the necessary files into your
1856	source directory without having to change even a single line in them, so	2371	source directory without having to change even a single line in them, so
1857	you can easily upgrade by simply copying (or having a checked-out copy of	2372	you can easily upgrade by simply copying (or having a checked-out copy of
1858	libev somewhere in your source tree).	2373	libev somewhere in your source tree).
1859		2374
1860	=head2 FILESETS	2375	=head2 FILESETS
…		…
1891	ev_vars.h	2406	ev_vars.h
1892	ev_wrap.h	2407	ev_wrap.h
1893		2408
1894	ev_win32.c required on win32 platforms only	2409	ev_win32.c required on win32 platforms only
1895		2410
1896	ev_select.c only when select backend is enabled (which is by default)	2411	ev_select.c only when select backend is enabled (which is enabled by default)
1897	ev_poll.c only when poll backend is enabled (disabled by default)	2412	ev_poll.c only when poll backend is enabled (disabled by default)
1898	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2413	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1899	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2414	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1900	ev_port.c only when the solaris port backend is enabled (disabled by default)	2415	ev_port.c only when the solaris port backend is enabled (disabled by default)
1901		2416
…		…
1950		2465
1951	If defined to be C<1>, libev will try to detect the availability of the	2466	If defined to be C<1>, libev will try to detect the availability of the
1952	monotonic clock option at both compiletime and runtime. Otherwise no use	2467	monotonic clock option at both compiletime and runtime. Otherwise no use
1953	of the monotonic clock option will be attempted. If you enable this, you	2468	of the monotonic clock option will be attempted. If you enable this, you
1954	usually have to link against librt or something similar. Enabling it when	2469	usually have to link against librt or something similar. Enabling it when
1955	the functionality isn't available is safe, though, althoguh you have	2470	the functionality isn't available is safe, though, although you have
1956	to make sure you link against any libraries where the C<clock_gettime>	2471	to make sure you link against any libraries where the C<clock_gettime>
1957	function is hiding in (often F<-lrt>).	2472	function is hiding in (often F<-lrt>).
1958		2473
1959	=item EV_USE_REALTIME	2474	=item EV_USE_REALTIME
1960		2475
1961	If defined to be C<1>, libev will try to detect the availability of the	2476	If defined to be C<1>, libev will try to detect the availability of the
1962	realtime clock option at compiletime (and assume its availability at	2477	realtime clock option at compiletime (and assume its availability at
1963	runtime if successful). Otherwise no use of the realtime clock option will	2478	runtime if successful). Otherwise no use of the realtime clock option will
1964	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2479	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1965	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2480	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1966	in the description of C<EV_USE_MONOTONIC>, though.	2481	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
		2482
		2483	=item EV_USE_NANOSLEEP
		2484
		2485	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
		2486	and will use it for delays. Otherwise it will use C<select ()>.
1967		2487
1968	=item EV_USE_SELECT	2488	=item EV_USE_SELECT
1969		2489
1970	If undefined or defined to be C<1>, libev will compile in support for the	2490	If undefined or defined to be C<1>, libev will compile in support for the
1971	C<select>(2) backend. No attempt at autodetection will be done: if no	2491	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
1989	wants osf handles on win32 (this is the case when the select to	2509	wants osf handles on win32 (this is the case when the select to
1990	be used is the winsock select). This means that it will call	2510	be used is the winsock select). This means that it will call
1991	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	2511	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
1992	it is assumed that all these functions actually work on fds, even	2512	it is assumed that all these functions actually work on fds, even
1993	on win32. Should not be defined on non-win32 platforms.	2513	on win32. Should not be defined on non-win32 platforms.
		2514
		2515	=item EV_FD_TO_WIN32_HANDLE
		2516
		2517	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
		2518	file descriptors to socket handles. When not defining this symbol (the
		2519	default), then libev will call C<_get_osfhandle>, which is usually
		2520	correct. In some cases, programs use their own file descriptor management,
		2521	in which case they can provide this function to map fds to socket handles.
1994		2522
1995	=item EV_USE_POLL	2523	=item EV_USE_POLL
1996		2524
1997	If defined to be C<1>, libev will compile in support for the C<poll>(2)	2525	If defined to be C<1>, libev will compile in support for the C<poll>(2)
1998	backend. Otherwise it will be enabled on non-win32 platforms. It	2526	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
2035	be detected at runtime.	2563	be detected at runtime.
2036		2564
2037	=item EV_H	2565	=item EV_H
2038		2566
2039	The name of the F<ev.h> header file used to include it. The default if	2567	The name of the F<ev.h> header file used to include it. The default if
2040	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2568	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
2041	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2569	used to virtually rename the F<ev.h> header file in case of conflicts.
2042		2570
2043	=item EV_CONFIG_H	2571	=item EV_CONFIG_H
2044		2572
2045	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	2573	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
2046	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	2574	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
2047	C<EV_H>, above.	2575	C<EV_H>, above.
2048		2576
2049	=item EV_EVENT_H	2577	=item EV_EVENT_H
2050		2578
2051	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	2579	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
2052	of how the F<event.h> header can be found.	2580	of how the F<event.h> header can be found, the default is C<"event.h">.
2053		2581
2054	=item EV_PROTOTYPES	2582	=item EV_PROTOTYPES
2055		2583
2056	If defined to be C<0>, then F<ev.h> will not define any function	2584	If defined to be C<0>, then F<ev.h> will not define any function
2057	prototypes, but still define all the structs and other symbols. This is	2585	prototypes, but still define all the structs and other symbols. This is
…		…
2064	will have the C<struct ev_loop *> as first argument, and you can create	2592	will have the C<struct ev_loop *> as first argument, and you can create
2065	additional independent event loops. Otherwise there will be no support	2593	additional independent event loops. Otherwise there will be no support
2066	for multiple event loops and there is no first event loop pointer	2594	for multiple event loops and there is no first event loop pointer
2067	argument. Instead, all functions act on the single default loop.	2595	argument. Instead, all functions act on the single default loop.
2068		2596
		2597	=item EV_MINPRI
		2598
		2599	=item EV_MAXPRI
		2600
		2601	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2602	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2603	provide for more priorities by overriding those symbols (usually defined
		2604	to be C<-2> and C<2>, respectively).
		2605
		2606	When doing priority-based operations, libev usually has to linearly search
		2607	all the priorities, so having many of them (hundreds) uses a lot of space
		2608	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2609	fine.
		2610
		2611	If your embedding app does not need any priorities, defining these both to
		2612	C<0> will save some memory and cpu.
		2613
2069	=item EV_PERIODIC_ENABLE	2614	=item EV_PERIODIC_ENABLE
2070		2615
2071	If undefined or defined to be C<1>, then periodic timers are supported. If	2616	If undefined or defined to be C<1>, then periodic timers are supported. If
		2617	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2618	code.
		2619
		2620	=item EV_IDLE_ENABLE
		2621
		2622	If undefined or defined to be C<1>, then idle watchers are supported. If
2072	defined to be C<0>, then they are not. Disabling them saves a few kB of	2623	defined to be C<0>, then they are not. Disabling them saves a few kB of
2073	code.	2624	code.
2074		2625
2075	=item EV_EMBED_ENABLE	2626	=item EV_EMBED_ENABLE
2076		2627
…		…
2100	than enough. If you need to manage thousands of children you might want to	2651	than enough. If you need to manage thousands of children you might want to
2101	increase this value (I<must> be a power of two).	2652	increase this value (I<must> be a power of two).
2102		2653
2103	=item EV_INOTIFY_HASHSIZE	2654	=item EV_INOTIFY_HASHSIZE
2104		2655
2105	C<ev_staz> watchers use a small hash table to distribute workload by	2656	C<ev_stat> watchers use a small hash table to distribute workload by
2106	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	2657	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2107	usually more than enough. If you need to manage thousands of C<ev_stat>	2658	usually more than enough. If you need to manage thousands of C<ev_stat>
2108	watchers you might want to increase this value (I<must> be a power of	2659	watchers you might want to increase this value (I<must> be a power of
2109	two).	2660	two).
2110		2661
…		…
2127		2678
2128	=item ev_set_cb (ev, cb)	2679	=item ev_set_cb (ev, cb)
2129		2680
2130	Can be used to change the callback member declaration in each watcher,	2681	Can be used to change the callback member declaration in each watcher,
2131	and the way callbacks are invoked and set. Must expand to a struct member	2682	and the way callbacks are invoked and set. Must expand to a struct member
2132	definition and a statement, respectively. See the F<ev.v> header file for	2683	definition and a statement, respectively. See the F<ev.h> header file for
2133	their default definitions. One possible use for overriding these is to	2684	their default definitions. One possible use for overriding these is to
2134	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2685	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2135	method calls instead of plain function calls in C++.	2686	method calls instead of plain function calls in C++.
		2687
		2688	=head2 EXPORTED API SYMBOLS
		2689
		2690	If you need to re-export the API (e.g. via a dll) and you need a list of
		2691	exported symbols, you can use the provided F<Symbol.*> files which list
		2692	all public symbols, one per line:
		2693
		2694	Symbols.ev for libev proper
		2695	Symbols.event for the libevent emulation
		2696
		2697	This can also be used to rename all public symbols to avoid clashes with
		2698	multiple versions of libev linked together (which is obviously bad in
		2699	itself, but sometimes it is inconvinient to avoid this).
		2700
		2701	A sed command like this will create wrapper C<#define>'s that you need to
		2702	include before including F<ev.h>:
		2703
		2704	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2705
		2706	This would create a file F<wrap.h> which essentially looks like this:
		2707
		2708	#define ev_backend myprefix_ev_backend
		2709	#define ev_check_start myprefix_ev_check_start
		2710	#define ev_check_stop myprefix_ev_check_stop
		2711	...
2136		2712
2137	=head2 EXAMPLES	2713	=head2 EXAMPLES
2138		2714
2139	For a real-world example of a program the includes libev	2715	For a real-world example of a program the includes libev
2140	verbatim, you can have a look at the EV perl module	2716	verbatim, you can have a look at the EV perl module
…		…
2143	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2719	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2144	will be compiled. It is pretty complex because it provides its own header	2720	will be compiled. It is pretty complex because it provides its own header
2145	file.	2721	file.
2146		2722
2147	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2723	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2148	that everybody includes and which overrides some autoconf choices:	2724	that everybody includes and which overrides some configure choices:
2149		2725
		2726	#define EV_MINIMAL 1
2150	#define EV_USE_POLL 0	2727	#define EV_USE_POLL 0
2151	#define EV_MULTIPLICITY 0	2728	#define EV_MULTIPLICITY 0
2152	#define EV_PERIODICS 0	2729	#define EV_PERIODIC_ENABLE 0
		2730	#define EV_STAT_ENABLE 0
		2731	#define EV_FORK_ENABLE 0
2153	#define EV_CONFIG_H <config.h>	2732	#define EV_CONFIG_H <config.h>
		2733	#define EV_MINPRI 0
		2734	#define EV_MAXPRI 0
2154		2735
2155	#include "ev++.h"	2736	#include "ev++.h"
2156		2737
2157	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2738	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2158		2739
…		…
2164		2745
2165	In this section the complexities of (many of) the algorithms used inside	2746	In this section the complexities of (many of) the algorithms used inside
2166	libev will be explained. For complexity discussions about backends see the	2747	libev will be explained. For complexity discussions about backends see the
2167	documentation for C<ev_default_init>.	2748	documentation for C<ev_default_init>.
2168		2749
		2750	All of the following are about amortised time: If an array needs to be
		2751	extended, libev needs to realloc and move the whole array, but this
		2752	happens asymptotically never with higher number of elements, so O(1) might
		2753	mean it might do a lengthy realloc operation in rare cases, but on average
		2754	it is much faster and asymptotically approaches constant time.
		2755
2169	=over 4	2756	=over 4
2170		2757
2171	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2758	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2172		2759
		2760	This means that, when you have a watcher that triggers in one hour and
		2761	there are 100 watchers that would trigger before that then inserting will
		2762	have to skip roughly seven (C<ld 100>) of these watchers.
		2763
2173	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2764	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
		2765
		2766	That means that changing a timer costs less than removing/adding them
		2767	as only the relative motion in the event queue has to be paid for.
2174		2768
2175	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2769	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2176		2770
		2771	These just add the watcher into an array or at the head of a list.
		2772
2177	=item Stopping check/prepare/idle watchers: O(1)	2773	=item Stopping check/prepare/idle watchers: O(1)
2178		2774
2179	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2775	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2180		2776
		2777	These watchers are stored in lists then need to be walked to find the
		2778	correct watcher to remove. The lists are usually short (you don't usually
		2779	have many watchers waiting for the same fd or signal).
		2780
2181	=item Finding the next timer per loop iteration: O(1)	2781	=item Finding the next timer in each loop iteration: O(1)
		2782
		2783	By virtue of using a binary heap, the next timer is always found at the
		2784	beginning of the storage array.
2182		2785
2183	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2786	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2184		2787
2185	=item Activating one watcher: O(1)	2788	A change means an I/O watcher gets started or stopped, which requires
		2789	libev to recalculate its status (and possibly tell the kernel, depending
		2790	on backend and wether C<ev_io_set> was used).
		2791
		2792	=item Activating one watcher (putting it into the pending state): O(1)
		2793
		2794	=item Priority handling: O(number_of_priorities)
		2795
		2796	Priorities are implemented by allocating some space for each
		2797	priority. When doing priority-based operations, libev usually has to
		2798	linearly search all the priorities, but starting/stopping and activating
		2799	watchers becomes O(1) w.r.t. prioritiy handling.
2186		2800
2187	=back	2801	=back
2188		2802
2189		2803
		2804	=head1 Win32 platform limitations and workarounds
		2805
		2806	Win32 doesn't support any of the standards (e.g. POSIX) that libev
		2807	requires, and its I/O model is fundamentally incompatible with the POSIX
		2808	model. Libev still offers limited functionality on this platform in
		2809	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
		2810	descriptors. This only applies when using Win32 natively, not when using
		2811	e.g. cygwin.
		2812
		2813	There is no supported compilation method available on windows except
		2814	embedding it into other applications.
		2815
		2816	Due to the many, low, and arbitrary limits on the win32 platform and the
		2817	abysmal performance of winsockets, using a large number of sockets is not
		2818	recommended (and not reasonable). If your program needs to use more than
		2819	a hundred or so sockets, then likely it needs to use a totally different
		2820	implementation for windows, as libev offers the POSIX model, which cannot
		2821	be implemented efficiently on windows (microsoft monopoly games).
		2822
		2823	=over 4
		2824
		2825	=item The winsocket select function
		2826
		2827	The winsocket C<select> function doesn't follow POSIX in that it requires
		2828	socket I<handles> and not socket I<file descriptors>. This makes select
		2829	very inefficient, and also requires a mapping from file descriptors
		2830	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,
		2831	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor
		2832	symbols for more info.
		2833
		2834	The configuration for a "naked" win32 using the microsoft runtime
		2835	libraries and raw winsocket select is:
		2836
		2837	#define EV_USE_SELECT 1
		2838	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
		2839
		2840	Note that winsockets handling of fd sets is O(n), so you can easily get a
		2841	complexity in the O(n²) range when using win32.
		2842
		2843	=item Limited number of file descriptors
		2844
		2845	Windows has numerous arbitrary (and low) limits on things. Early versions
		2846	of winsocket's select only supported waiting for a max. of C<64> handles
		2847	(probably owning to the fact that all windows kernels can only wait for
		2848	C<64> things at the same time internally; microsoft recommends spawning a
		2849	chain of threads and wait for 63 handles and the previous thread in each).
		2850
		2851	Newer versions support more handles, but you need to define C<FD_SETSIZE>
		2852	to some high number (e.g. C<2048>) before compiling the winsocket select
		2853	call (which might be in libev or elsewhere, for example, perl does its own
		2854	select emulation on windows).
		2855
		2856	Another limit is the number of file descriptors in the microsoft runtime
		2857	libraries, which by default is C<64> (there must be a hidden I<64> fetish
		2858	or something like this inside microsoft). You can increase this by calling
		2859	C<_setmaxstdio>, which can increase this limit to C<2048> (another
		2860	arbitrary limit), but is broken in many versions of the microsoft runtime
		2861	libraries.
		2862
		2863	This might get you to about C<512> or C<2048> sockets (depending on
		2864	windows version and/or the phase of the moon). To get more, you need to
		2865	wrap all I/O functions and provide your own fd management, but the cost of
		2866	calling select (O(n²)) will likely make this unworkable.
		2867
		2868	=back
		2869
		2870
2190	=head1 AUTHOR	2871	=head1 AUTHOR
2191		2872
2192	Marc Lehmann <libev@schmorp.de>.	2873	Marc Lehmann <libev@schmorp.de>.
2193		2874

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