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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;
…		…
53	The newest version of this document is also available as a html-formatted	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	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>.	55	time: L<http://cvs.schmorp.de/libev/ev.html>.
56		56
57	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
58	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
59	these event sources and provide your program with events.	59	these event sources and provide your program with events.
60		60
61	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
62	(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
63	communicate events via a callback mechanism.	63	communicate events via a callback mechanism.
…		…
65	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
66	watchers>, which are relatively small C structures you initialise with the	66	watchers>, which are relatively small C structures you initialise with the
67	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
68	watcher.	68	watcher.
69		69
70	=head1 FEATURES	70	=head2 FEATURES
71		71
72	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
73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
74	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
75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers	75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
…		…
82		82
83	It also is quite fast (see this	83	It also is quite fast (see this
84	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
85	for example).	85	for example).
86		86
87	=head1 CONVENTIONS	87	=head2 CONVENTIONS
88		88
89	Libev is very configurable. In this manual the default configuration will	89	Libev is very configurable. In this manual the default configuration will
90	be described, which supports multiple event loops. For more info about	90	be described, which supports multiple event loops. For more info about
91	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
92	this manual. If libev was configured without support for multiple event	92	this manual. If libev was configured without support for multiple event
93	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>
94	(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.
95		95
96	=head1 TIME REPRESENTATION	96	=head2 TIME REPRESENTATION
97		97
98	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
99	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
100	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
101	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
102	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
103	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.
104		106
105	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
106		108
107	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
108	library in any way.	110	library in any way.
…		…
113		115
114	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
115	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
116	you actually want to know.	118	you actually want to know.
117		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
118	=item int ev_version_major ()	126	=item int ev_version_major ()
119		127
120	=item int ev_version_minor ()	128	=item int ev_version_minor ()
121		129
122	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
123	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
124	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
125	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
126	version of the library your program was compiled against.	134	version of the library your program was compiled against.
127		135
		136	These version numbers refer to the ABI version of the library, not the
		137	release version.
		138
128	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,
129	as this indicates an incompatible change. Minor versions are usually	140	as this indicates an incompatible change. Minor versions are usually
130	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
131	not a problem.	142	not a problem.
132		143
133	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
134	version.	145	version.
…		…
249	flags. If that is troubling you, check C<ev_backend ()> afterwards).	260	flags. If that is troubling you, check C<ev_backend ()> afterwards).
250		261
251	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
252	function.	263	function.
253		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
254	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
255	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>).
256		274
257	The following flags are supported:	275	The following flags are supported:
258		276
…		…
295	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	313	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
296		314
297	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
298	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,
299	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
300	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
301	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.
302		327
303	=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)
304		329
305	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
306	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
307	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
308	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.
309		336
310	=item C<EVBACKEND_EPOLL> (value 4, Linux)	337	=item C<EVBACKEND_EPOLL> (value 4, Linux)
311		338
312	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,
313	but it scales phenomenally better. While poll and select usually scale like	340	but it scales phenomenally better. While poll and select usually scale
314	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),
315	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.
316		346
317	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
318	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
319	(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
320	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
321	well if you register events for both fds.	351	very well if you register events for both fds.
322		352
323	Please note that epoll sometimes generates spurious notifications, so you	353	Please note that epoll sometimes generates spurious notifications, so you
324	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
325	(or space) is available.	355	(or space) is available.
326		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
327	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	364	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
328		365
329	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
330	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
331	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
332	completely useless). For this reason its not being "autodetected"	369	it's completely useless). For this reason it's not being "autodetected"
333	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
334	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.
335		377
336	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
337	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
338	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
339	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
340	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.
341		393
342	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	394	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
343		395
344	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.
345		400
346	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	401	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
347		402
348	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,
349	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)).
350		405
351	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
352	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
353	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.
354		418
355	=item C<EVBACKEND_ALL>	419	=item C<EVBACKEND_ALL>
356		420
357	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
358	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
359	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	423	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
360		424
		425	It is definitely not recommended to use this flag.
		426
361	=back	427	=back
362		428
363	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
364	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
365	specified, most compiled-in backend will be tried, usually in reverse	431	specified, all backends in C<ev_recommended_backends ()> will be tried.
366	order of their flag values :)
367		432
368	The most typical usage is like this:	433	The most typical usage is like this:
369		434
370	if (!ev_default_loop (0))	435	if (!ev_default_loop (0))
371	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	436	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
…		…
399	Destroys the default loop again (frees all memory and kernel state	464	Destroys the default loop again (frees all memory and kernel state
400	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
401	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
402	responsibility to either stop all watchers cleanly yoursef I<before>	467	responsibility to either stop all watchers cleanly yoursef I<before>
403	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
404	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
405	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>).
406		480
407	=item ev_loop_destroy (loop)	481	=item ev_loop_destroy (loop)
408		482
409	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
410	earlier call to C<ev_loop_new>.	484	earlier call to C<ev_loop_new>.
411		485
412	=item ev_default_fork ()	486	=item ev_default_fork ()
413		487
		488	This function sets a flag that causes subsequent C<ev_loop> iterations
414	This function reinitialises the kernel state for backends that have	489	to reinitialise the kernel state for backends that have one. Despite the
415	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
416	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
417	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.
418		494
419	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
420	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
421	fork+exec, you don't have to call it.	497	you just fork+exec, you don't have to call it at all.
422		498
423	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
424	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
425	quite nicely into a call to C<pthread_atfork>:	501	quite nicely into a call to C<pthread_atfork>:
426		502
427	pthread_atfork (0, 0, ev_default_fork);	503	pthread_atfork (0, 0, ev_default_fork);
428		504
429	At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use
430	without calling this function, so if you force one of those backends you
431	do not need to care.
432
433	=item ev_loop_fork (loop)	505	=item ev_loop_fork (loop)
434		506
435	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
436	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
437	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 int ev_is_default_loop (loop)
		512
		513	Returns true when the given loop actually is the default loop, false otherwise.
438		514
439	=item unsigned int ev_loop_count (loop)	515	=item unsigned int ev_loop_count (loop)
440		516
441	Returns the count of loop iterations for the loop, which is identical to	517	Returns the count of loop iterations for the loop, which is identical to
442	the number of times libev did poll for new events. It starts at C<0> and	518	the number of times libev did poll for new events. It starts at C<0> and
…		…
455		531
456	Returns the current "event loop time", which is the time the event loop	532	Returns the current "event loop time", which is the time the event loop
457	received events and started processing them. This timestamp does not	533	received events and started processing them. This timestamp does not
458	change as long as callbacks are being processed, and this is also the base	534	change as long as callbacks are being processed, and this is also the base
459	time used for relative timers. You can treat it as the timestamp of the	535	time used for relative timers. You can treat it as the timestamp of the
460	event occuring (or more correctly, libev finding out about it).	536	event occurring (or more correctly, libev finding out about it).
461		537
462	=item ev_loop (loop, int flags)	538	=item ev_loop (loop, int flags)
463		539
464	Finally, this is it, the event handler. This function usually is called	540	Finally, this is it, the event handler. This function usually is called
465	after you initialised all your watchers and you want to start handling	541	after you initialised all your watchers and you want to start handling
…		…
486	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	562	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
487	usually a better approach for this kind of thing.	563	usually a better approach for this kind of thing.
488		564
489	Here are the gory details of what C<ev_loop> does:	565	Here are the gory details of what C<ev_loop> does:
490		566
491	* If there are no active watchers (reference count is zero), return.	567	- Before the first iteration, call any pending watchers.
492	- Queue prepare watchers and then call all outstanding watchers.	568	* If EVFLAG_FORKCHECK was used, check for a fork.
		569	- If a fork was detected, queue and call all fork watchers.
		570	- Queue and call all prepare watchers.
493	- If we have been forked, recreate the kernel state.	571	- If we have been forked, recreate the kernel state.
494	- Update the kernel state with all outstanding changes.	572	- Update the kernel state with all outstanding changes.
495	- Update the "event loop time".	573	- Update the "event loop time".
496	- Calculate for how long to block.	574	- Calculate for how long to sleep or block, if at all
		575	(active idle watchers, EVLOOP_NONBLOCK or not having
		576	any active watchers at all will result in not sleeping).
		577	- Sleep if the I/O and timer collect interval say so.
497	- Block the process, waiting for any events.	578	- Block the process, waiting for any events.
498	- Queue all outstanding I/O (fd) events.	579	- Queue all outstanding I/O (fd) events.
499	- Update the "event loop time" and do time jump handling.	580	- Update the "event loop time" and do time jump handling.
500	- Queue all outstanding timers.	581	- Queue all outstanding timers.
501	- Queue all outstanding periodics.	582	- Queue all outstanding periodics.
502	- If no events are pending now, queue all idle watchers.	583	- If no events are pending now, queue all idle watchers.
503	- Queue all check watchers.	584	- Queue all check watchers.
504	- Call all queued watchers in reverse order (i.e. check watchers first).	585	- Call all queued watchers in reverse order (i.e. check watchers first).
505	Signals and child watchers are implemented as I/O watchers, and will	586	Signals and child watchers are implemented as I/O watchers, and will
506	be handled here by queueing them when their watcher gets executed.	587	be handled here by queueing them when their watcher gets executed.
507	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	588	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
508	were used, return, otherwise continue with step *.	589	were used, or there are no active watchers, return, otherwise
		590	continue with step *.
509		591
510	Example: Queue some jobs and then loop until no events are outsanding	592	Example: Queue some jobs and then loop until no events are outstanding
511	anymore.	593	anymore.
512		594
513	... queue jobs here, make sure they register event watchers as long	595	... queue jobs here, make sure they register event watchers as long
514	... as they still have work to do (even an idle watcher will do..)	596	... as they still have work to do (even an idle watcher will do..)
515	ev_loop (my_loop, 0);	597	ev_loop (my_loop, 0);
…		…
519		601
520	Can be used to make a call to C<ev_loop> return early (but only after it	602	Can be used to make a call to C<ev_loop> return early (but only after it
521	has processed all outstanding events). The C<how> argument must be either	603	has processed all outstanding events). The C<how> argument must be either
522	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	604	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or
523	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	605	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
		606
		607	This "unloop state" will be cleared when entering C<ev_loop> again.
524		608
525	=item ev_ref (loop)	609	=item ev_ref (loop)
526		610
527	=item ev_unref (loop)	611	=item ev_unref (loop)
528		612
…		…
533	returning, ev_unref() after starting, and ev_ref() before stopping it. For	617	returning, ev_unref() after starting, and ev_ref() before stopping it. For
534	example, libev itself uses this for its internal signal pipe: It is not	618	example, libev itself uses this for its internal signal pipe: It is not
535	visible to the libev user and should not keep C<ev_loop> from exiting if	619	visible to the libev user and should not keep C<ev_loop> from exiting if
536	no event watchers registered by it are active. It is also an excellent	620	no event watchers registered by it are active. It is also an excellent
537	way to do this for generic recurring timers or from within third-party	621	way to do this for generic recurring timers or from within third-party
538	libraries. Just remember to I<unref after start> and I<ref before stop>.	622	libraries. Just remember to I<unref after start> and I<ref before stop>
		623	(but only if the watcher wasn't active before, or was active before,
		624	respectively).
539		625
540	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	626	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
541	running when nothing else is active.	627	running when nothing else is active.
542		628
543	struct ev_signal exitsig;	629	struct ev_signal exitsig;
…		…
547		633
548	Example: For some weird reason, unregister the above signal handler again.	634	Example: For some weird reason, unregister the above signal handler again.
549		635
550	ev_ref (loop);	636	ev_ref (loop);
551	ev_signal_stop (loop, &exitsig);	637	ev_signal_stop (loop, &exitsig);
		638
		639	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
		640
		641	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
		642
		643	These advanced functions influence the time that libev will spend waiting
		644	for events. Both are by default C<0>, meaning that libev will try to
		645	invoke timer/periodic callbacks and I/O callbacks with minimum latency.
		646
		647	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
		648	allows libev to delay invocation of I/O and timer/periodic callbacks to
		649	increase efficiency of loop iterations.
		650
		651	The background is that sometimes your program runs just fast enough to
		652	handle one (or very few) event(s) per loop iteration. While this makes
		653	the program responsive, it also wastes a lot of CPU time to poll for new
		654	events, especially with backends like C<select ()> which have a high
		655	overhead for the actual polling but can deliver many events at once.
		656
		657	By setting a higher I<io collect interval> you allow libev to spend more
		658	time collecting I/O events, so you can handle more events per iteration,
		659	at the cost of increasing latency. Timeouts (both C<ev_periodic> and
		660	C<ev_timer>) will be not affected. Setting this to a non-null value will
		661	introduce an additional C<ev_sleep ()> call into most loop iterations.
		662
		663	Likewise, by setting a higher I<timeout collect interval> you allow libev
		664	to spend more time collecting timeouts, at the expense of increased
		665	latency (the watcher callback will be called later). C<ev_io> watchers
		666	will not be affected. Setting this to a non-null value will not introduce
		667	any overhead in libev.
		668
		669	Many (busy) programs can usually benefit by setting the io collect
		670	interval to a value near C<0.1> or so, which is often enough for
		671	interactive servers (of course not for games), likewise for timeouts. It
		672	usually doesn't make much sense to set it to a lower value than C<0.01>,
		673	as this approsaches the timing granularity of most systems.
552		674
553	=back	675	=back
554		676
555		677
556	=head1 ANATOMY OF A WATCHER	678	=head1 ANATOMY OF A WATCHER
…		…
656	=item C<EV_FORK>	778	=item C<EV_FORK>
657		779
658	The event loop has been resumed in the child process after fork (see	780	The event loop has been resumed in the child process after fork (see
659	C<ev_fork>).	781	C<ev_fork>).
660		782
		783	=item C<EV_ASYNC>
		784
		785	The given async watcher has been asynchronously notified (see C<ev_async>).
		786
661	=item C<EV_ERROR>	787	=item C<EV_ERROR>
662		788
663	An unspecified error has occured, the watcher has been stopped. This might	789	An unspecified error has occured, the watcher has been stopped. This might
664	happen because the watcher could not be properly started because libev	790	happen because the watcher could not be properly started because libev
665	ran out of memory, a file descriptor was found to be closed or any other	791	ran out of memory, a file descriptor was found to be closed or any other
…		…
736	=item bool ev_is_pending (ev_TYPE *watcher)	862	=item bool ev_is_pending (ev_TYPE *watcher)
737		863
738	Returns a true value iff the watcher is pending, (i.e. it has outstanding	864	Returns a true value iff the watcher is pending, (i.e. it has outstanding
739	events but its callback has not yet been invoked). As long as a watcher	865	events but its callback has not yet been invoked). As long as a watcher
740	is pending (but not active) you must not call an init function on it (but	866	is pending (but not active) you must not call an init function on it (but
741	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	867	C<ev_TYPE_set> is safe), you must not change its priority, and you must
742	libev (e.g. you cnanot C<free ()> it).	868	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		869	it).
743		870
744	=item callback ev_cb (ev_TYPE *watcher)	871	=item callback ev_cb (ev_TYPE *watcher)
745		872
746	Returns the callback currently set on the watcher.	873	Returns the callback currently set on the watcher.
747		874
…		…
766	watchers on the same event and make sure one is called first.	893	watchers on the same event and make sure one is called first.
767		894
768	If you need to suppress invocation when higher priority events are pending	895	If you need to suppress invocation when higher priority events are pending
769	you need to look at C<ev_idle> watchers, which provide this functionality.	896	you need to look at C<ev_idle> watchers, which provide this functionality.
770		897
		898	You I<must not> change the priority of a watcher as long as it is active or
		899	pending.
		900
771	The default priority used by watchers when no priority has been set is	901	The default priority used by watchers when no priority has been set is
772	always C<0>, which is supposed to not be too high and not be too low :).	902	always C<0>, which is supposed to not be too high and not be too low :).
773		903
774	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is	904	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
775	fine, as long as you do not mind that the priority value you query might	905	fine, as long as you do not mind that the priority value you query might
776	or might not have been adjusted to be within valid range.	906	or might not have been adjusted to be within valid range.
		907
		908	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		909
		910	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		911	C<loop> nor C<revents> need to be valid as long as the watcher callback
		912	can deal with that fact.
		913
		914	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		915
		916	If the watcher is pending, this function returns clears its pending status
		917	and returns its C<revents> bitset (as if its callback was invoked). If the
		918	watcher isn't pending it does nothing and returns C<0>.
777		919
778	=back	920	=back
779		921
780		922
781	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	923	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
866	In general you can register as many read and/or write event watchers per	1008	In general you can register as many read and/or write event watchers per
867	fd as you want (as long as you don't confuse yourself). Setting all file	1009	fd as you want (as long as you don't confuse yourself). Setting all file
868	descriptors to non-blocking mode is also usually a good idea (but not	1010	descriptors to non-blocking mode is also usually a good idea (but not
869	required if you know what you are doing).	1011	required if you know what you are doing).
870		1012
871	You have to be careful with dup'ed file descriptors, though. Some backends
872	(the linux epoll backend is a notable example) cannot handle dup'ed file
873	descriptors correctly if you register interest in two or more fds pointing
874	to the same underlying file/socket/etc. description (that is, they share
875	the same underlying "file open").
876
877	If you must do this, then force the use of a known-to-be-good backend	1013	If you must do this, then force the use of a known-to-be-good backend
878	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1014	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
879	C<EVBACKEND_POLL>).	1015	C<EVBACKEND_POLL>).
880		1016
881	Another thing you have to watch out for is that it is quite easy to	1017	Another thing you have to watch out for is that it is quite easy to
…		…
891	play around with an Xlib connection), then you have to seperately re-test	1027	play around with an Xlib connection), then you have to seperately re-test
892	whether a file descriptor is really ready with a known-to-be good interface	1028	whether a file descriptor is really ready with a known-to-be good interface
893	such as poll (fortunately in our Xlib example, Xlib already does this on	1029	such as poll (fortunately in our Xlib example, Xlib already does this on
894	its own, so its quite safe to use).	1030	its own, so its quite safe to use).
895		1031
		1032	=head3 The special problem of disappearing file descriptors
		1033
		1034	Some backends (e.g. kqueue, epoll) need to be told about closing a file
		1035	descriptor (either by calling C<close> explicitly or by any other means,
		1036	such as C<dup>). The reason is that you register interest in some file
		1037	descriptor, but when it goes away, the operating system will silently drop
		1038	this interest. If another file descriptor with the same number then is
		1039	registered with libev, there is no efficient way to see that this is, in
		1040	fact, a different file descriptor.
		1041
		1042	To avoid having to explicitly tell libev about such cases, libev follows
		1043	the following policy: Each time C<ev_io_set> is being called, libev
		1044	will assume that this is potentially a new file descriptor, otherwise
		1045	it is assumed that the file descriptor stays the same. That means that
		1046	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		1047	descriptor even if the file descriptor number itself did not change.
		1048
		1049	This is how one would do it normally anyway, the important point is that
		1050	the libev application should not optimise around libev but should leave
		1051	optimisations to libev.
		1052
		1053	=head3 The special problem of dup'ed file descriptors
		1054
		1055	Some backends (e.g. epoll), cannot register events for file descriptors,
		1056	but only events for the underlying file descriptions. That means when you
		1057	have C<dup ()>'ed file descriptors or weirder constellations, and register
		1058	events for them, only one file descriptor might actually receive events.
		1059
		1060	There is no workaround possible except not registering events
		1061	for potentially C<dup ()>'ed file descriptors, or to resort to
		1062	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
		1063
		1064	=head3 The special problem of fork
		1065
		1066	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
		1067	useless behaviour. Libev fully supports fork, but needs to be told about
		1068	it in the child.
		1069
		1070	To support fork in your programs, you either have to call
		1071	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
		1072	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
		1073	C<EVBACKEND_POLL>.
		1074
		1075
		1076	=head3 Watcher-Specific Functions
		1077
896	=over 4	1078	=over 4
897		1079
898	=item ev_io_init (ev_io *, callback, int fd, int events)	1080	=item ev_io_init (ev_io *, callback, int fd, int events)
899		1081
900	=item ev_io_set (ev_io *, int fd, int events)	1082	=item ev_io_set (ev_io *, int fd, int events)
…		…
910	=item int events [read-only]	1092	=item int events [read-only]
911		1093
912	The events being watched.	1094	The events being watched.
913		1095
914	=back	1096	=back
		1097
		1098	=head3 Examples
915		1099
916	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1100	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
917	readable, but only once. Since it is likely line-buffered, you could	1101	readable, but only once. Since it is likely line-buffered, you could
918	attempt to read a whole line in the callback.	1102	attempt to read a whole line in the callback.
919		1103
…		…
953		1137
954	The callback is guarenteed to be invoked only when its timeout has passed,	1138	The callback is guarenteed to be invoked only when its timeout has passed,
955	but if multiple timers become ready during the same loop iteration then	1139	but if multiple timers become ready during the same loop iteration then
956	order of execution is undefined.	1140	order of execution is undefined.
957		1141
		1142	=head3 Watcher-Specific Functions and Data Members
		1143
958	=over 4	1144	=over 4
959		1145
960	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1146	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
961		1147
962	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1148	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
970	configure a timer to trigger every 10 seconds, then it will trigger at	1156	configure a timer to trigger every 10 seconds, then it will trigger at
971	exactly 10 second intervals. If, however, your program cannot keep up with	1157	exactly 10 second intervals. If, however, your program cannot keep up with
972	the timer (because it takes longer than those 10 seconds to do stuff) the	1158	the timer (because it takes longer than those 10 seconds to do stuff) the
973	timer will not fire more than once per event loop iteration.	1159	timer will not fire more than once per event loop iteration.
974		1160
975	=item ev_timer_again (loop)	1161	=item ev_timer_again (loop, ev_timer *)
976		1162
977	This will act as if the timer timed out and restart it again if it is	1163	This will act as if the timer timed out and restart it again if it is
978	repeating. The exact semantics are:	1164	repeating. The exact semantics are:
979		1165
980	If the timer is pending, its pending status is cleared.	1166	If the timer is pending, its pending status is cleared.
…		…
1015	or C<ev_timer_again> is called and determines the next timeout (if any),	1201	or C<ev_timer_again> is called and determines the next timeout (if any),
1016	which is also when any modifications are taken into account.	1202	which is also when any modifications are taken into account.
1017		1203
1018	=back	1204	=back
1019		1205
		1206	=head3 Examples
		1207
1020	Example: Create a timer that fires after 60 seconds.	1208	Example: Create a timer that fires after 60 seconds.
1021		1209
1022	static void	1210	static void
1023	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1211	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1024	{	1212	{
…		…
1057	but on wallclock time (absolute time). You can tell a periodic watcher	1245	but on wallclock time (absolute time). You can tell a periodic watcher
1058	to trigger "at" some specific point in time. For example, if you tell a	1246	to trigger "at" some specific point in time. For example, if you tell a
1059	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1247	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
1060	+ 10.>) and then reset your system clock to the last year, then it will	1248	+ 10.>) and then reset your system clock to the last year, then it will
1061	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1249	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
1062	roughly 10 seconds later and of course not if you reset your system time	1250	roughly 10 seconds later).
1063	again).
1064		1251
1065	They can also be used to implement vastly more complex timers, such as	1252	They can also be used to implement vastly more complex timers, such as
1066	triggering an event on eahc midnight, local time.	1253	triggering an event on each midnight, local time or other, complicated,
		1254	rules.
1067		1255
1068	As with timers, the callback is guarenteed to be invoked only when the	1256	As with timers, the callback is guarenteed to be invoked only when the
1069	time (C<at>) has been passed, but if multiple periodic timers become ready	1257	time (C<at>) has been passed, but if multiple periodic timers become ready
1070	during the same loop iteration then order of execution is undefined.	1258	during the same loop iteration then order of execution is undefined.
1071		1259
		1260	=head3 Watcher-Specific Functions and Data Members
		1261
1072	=over 4	1262	=over 4
1073		1263
1074	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1264	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
1075		1265
1076	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1266	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
1078	Lots of arguments, lets sort it out... There are basically three modes of	1268	Lots of arguments, lets sort it out... There are basically three modes of
1079	operation, and we will explain them from simplest to complex:	1269	operation, and we will explain them from simplest to complex:
1080		1270
1081	=over 4	1271	=over 4
1082		1272
1083	=item * absolute timer (interval = reschedule_cb = 0)	1273	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1084		1274
1085	In this configuration the watcher triggers an event at the wallclock time	1275	In this configuration the watcher triggers an event at the wallclock time
1086	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1276	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
1087	that is, if it is to be run at January 1st 2011 then it will run when the	1277	that is, if it is to be run at January 1st 2011 then it will run when the
1088	system time reaches or surpasses this time.	1278	system time reaches or surpasses this time.
1089		1279
1090	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1280	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1091		1281
1092	In this mode the watcher will always be scheduled to time out at the next	1282	In this mode the watcher will always be scheduled to time out at the next
1093	C<at + N * interval> time (for some integer N) and then repeat, regardless	1283	C<at + N * interval> time (for some integer N, which can also be negative)
1094	of any time jumps.	1284	and then repeat, regardless of any time jumps.
1095		1285
1096	This can be used to create timers that do not drift with respect to system	1286	This can be used to create timers that do not drift with respect to system
1097	time:	1287	time:
1098		1288
1099	ev_periodic_set (&periodic, 0., 3600., 0);	1289	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1105		1295
1106	Another way to think about it (for the mathematically inclined) is that	1296	Another way to think about it (for the mathematically inclined) is that
1107	C<ev_periodic> will try to run the callback in this mode at the next possible	1297	C<ev_periodic> will try to run the callback in this mode at the next possible
1108	time where C<time = at (mod interval)>, regardless of any time jumps.	1298	time where C<time = at (mod interval)>, regardless of any time jumps.
1109		1299
		1300	For numerical stability it is preferable that the C<at> value is near
		1301	C<ev_now ()> (the current time), but there is no range requirement for
		1302	this value.
		1303
1110	=item * manual reschedule mode (reschedule_cb = callback)	1304	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1111		1305
1112	In this mode the values for C<interval> and C<at> are both being	1306	In this mode the values for C<interval> and C<at> are both being
1113	ignored. Instead, each time the periodic watcher gets scheduled, the	1307	ignored. Instead, each time the periodic watcher gets scheduled, the
1114	reschedule callback will be called with the watcher as first, and the	1308	reschedule callback will be called with the watcher as first, and the
1115	current time as second argument.	1309	current time as second argument.
1116		1310
1117	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1311	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1118	ever, or make any event loop modifications>. If you need to stop it,	1312	ever, or make any event loop modifications>. If you need to stop it,
1119	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1313	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1120	starting a prepare watcher).	1314	starting an C<ev_prepare> watcher, which is legal).
1121		1315
1122	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1316	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1123	ev_tstamp now)>, e.g.:	1317	ev_tstamp now)>, e.g.:
1124		1318
1125	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1319	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1148	Simply stops and restarts the periodic watcher again. This is only useful	1342	Simply stops and restarts the periodic watcher again. This is only useful
1149	when you changed some parameters or the reschedule callback would return	1343	when you changed some parameters or the reschedule callback would return
1150	a different time than the last time it was called (e.g. in a crond like	1344	a different time than the last time it was called (e.g. in a crond like
1151	program when the crontabs have changed).	1345	program when the crontabs have changed).
1152		1346
		1347	=item ev_tstamp offset [read-write]
		1348
		1349	When repeating, this contains the offset value, otherwise this is the
		1350	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1351
		1352	Can be modified any time, but changes only take effect when the periodic
		1353	timer fires or C<ev_periodic_again> is being called.
		1354
1153	=item ev_tstamp interval [read-write]	1355	=item ev_tstamp interval [read-write]
1154		1356
1155	The current interval value. Can be modified any time, but changes only	1357	The current interval value. Can be modified any time, but changes only
1156	take effect when the periodic timer fires or C<ev_periodic_again> is being	1358	take effect when the periodic timer fires or C<ev_periodic_again> is being
1157	called.	1359	called.
…		…
1160		1362
1161	The current reschedule callback, or C<0>, if this functionality is	1363	The current reschedule callback, or C<0>, if this functionality is
1162	switched off. Can be changed any time, but changes only take effect when	1364	switched off. Can be changed any time, but changes only take effect when
1163	the periodic timer fires or C<ev_periodic_again> is being called.	1365	the periodic timer fires or C<ev_periodic_again> is being called.
1164		1366
		1367	=item ev_tstamp at [read-only]
		1368
		1369	When active, contains the absolute time that the watcher is supposed to
		1370	trigger next.
		1371
1165	=back	1372	=back
		1373
		1374	=head3 Examples
1166		1375
1167	Example: Call a callback every hour, or, more precisely, whenever the	1376	Example: Call a callback every hour, or, more precisely, whenever the
1168	system clock is divisible by 3600. The callback invocation times have	1377	system clock is divisible by 3600. The callback invocation times have
1169	potentially a lot of jittering, but good long-term stability.	1378	potentially a lot of jittering, but good long-term stability.
1170		1379
…		…
1210	with the kernel (thus it coexists with your own signal handlers as long	1419	with the kernel (thus it coexists with your own signal handlers as long
1211	as you don't register any with libev). Similarly, when the last signal	1420	as you don't register any with libev). Similarly, when the last signal
1212	watcher for a signal is stopped libev will reset the signal handler to	1421	watcher for a signal is stopped libev will reset the signal handler to
1213	SIG_DFL (regardless of what it was set to before).	1422	SIG_DFL (regardless of what it was set to before).
1214		1423
		1424	=head3 Watcher-Specific Functions and Data Members
		1425
1215	=over 4	1426	=over 4
1216		1427
1217	=item ev_signal_init (ev_signal *, callback, int signum)	1428	=item ev_signal_init (ev_signal *, callback, int signum)
1218		1429
1219	=item ev_signal_set (ev_signal *, int signum)	1430	=item ev_signal_set (ev_signal *, int signum)
…		…
1225		1436
1226	The signal the watcher watches out for.	1437	The signal the watcher watches out for.
1227		1438
1228	=back	1439	=back
1229		1440
		1441	=head3 Examples
		1442
		1443	Example: Try to exit cleanly on SIGINT and SIGTERM.
		1444
		1445	static void
		1446	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
		1447	{
		1448	ev_unloop (loop, EVUNLOOP_ALL);
		1449	}
		1450
		1451	struct ev_signal signal_watcher;
		1452	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
		1453	ev_signal_start (loop, &sigint_cb);
		1454
1230		1455
1231	=head2 C<ev_child> - watch out for process status changes	1456	=head2 C<ev_child> - watch out for process status changes
1232		1457
1233	Child watchers trigger when your process receives a SIGCHLD in response to	1458	Child watchers trigger when your process receives a SIGCHLD in response to
1234	some child status changes (most typically when a child of yours dies).	1459	some child status changes (most typically when a child of yours dies).
1235		1460
		1461	=head3 Watcher-Specific Functions and Data Members
		1462
1236	=over 4	1463	=over 4
1237		1464
1238	=item ev_child_init (ev_child *, callback, int pid)	1465	=item ev_child_init (ev_child *, callback, int pid, int trace)
1239		1466
1240	=item ev_child_set (ev_child *, int pid)	1467	=item ev_child_set (ev_child *, int pid, int trace)
1241		1468
1242	Configures the watcher to wait for status changes of process C<pid> (or	1469	Configures the watcher to wait for status changes of process C<pid> (or
1243	I<any> process if C<pid> is specified as C<0>). The callback can look	1470	I<any> process if C<pid> is specified as C<0>). The callback can look
1244	at the C<rstatus> member of the C<ev_child> watcher structure to see	1471	at the C<rstatus> member of the C<ev_child> watcher structure to see
1245	the status word (use the macros from C<sys/wait.h> and see your systems	1472	the status word (use the macros from C<sys/wait.h> and see your systems
1246	C<waitpid> documentation). The C<rpid> member contains the pid of the	1473	C<waitpid> documentation). The C<rpid> member contains the pid of the
1247	process causing the status change.	1474	process causing the status change. C<trace> must be either C<0> (only
		1475	activate the watcher when the process terminates) or C<1> (additionally
		1476	activate the watcher when the process is stopped or continued).
1248		1477
1249	=item int pid [read-only]	1478	=item int pid [read-only]
1250		1479
1251	The process id this watcher watches out for, or C<0>, meaning any process id.	1480	The process id this watcher watches out for, or C<0>, meaning any process id.
1252		1481
…		…
1258		1487
1259	The process exit/trace status caused by C<rpid> (see your systems	1488	The process exit/trace status caused by C<rpid> (see your systems
1260	C<waitpid> and C<sys/wait.h> documentation for details).	1489	C<waitpid> and C<sys/wait.h> documentation for details).
1261		1490
1262	=back	1491	=back
1263
1264	Example: Try to exit cleanly on SIGINT and SIGTERM.
1265
1266	static void
1267	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1268	{
1269	ev_unloop (loop, EVUNLOOP_ALL);
1270	}
1271
1272	struct ev_signal signal_watcher;
1273	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1274	ev_signal_start (loop, &sigint_cb);
1275		1492
1276		1493
1277	=head2 C<ev_stat> - did the file attributes just change?	1494	=head2 C<ev_stat> - did the file attributes just change?
1278		1495
1279	This watches a filesystem path for attribute changes. That is, it calls	1496	This watches a filesystem path for attribute changes. That is, it calls
…		…
1308	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1525	semantics of C<ev_stat> watchers, which means that libev sometimes needs
1309	to fall back to regular polling again even with inotify, but changes are	1526	to fall back to regular polling again even with inotify, but changes are
1310	usually detected immediately, and if the file exists there will be no	1527	usually detected immediately, and if the file exists there will be no
1311	polling.	1528	polling.
1312		1529
		1530	=head3 Inotify
		1531
		1532	When C<inotify (7)> support has been compiled into libev (generally only
		1533	available on Linux) and present at runtime, it will be used to speed up
		1534	change detection where possible. The inotify descriptor will be created lazily
		1535	when the first C<ev_stat> watcher is being started.
		1536
		1537	Inotify presense does not change the semantics of C<ev_stat> watchers
		1538	except that changes might be detected earlier, and in some cases, to avoid
		1539	making regular C<stat> calls. Even in the presense of inotify support
		1540	there are many cases where libev has to resort to regular C<stat> polling.
		1541
		1542	(There is no support for kqueue, as apparently it cannot be used to
		1543	implement this functionality, due to the requirement of having a file
		1544	descriptor open on the object at all times).
		1545
		1546	=head3 The special problem of stat time resolution
		1547
		1548	The C<stat ()> syscall only supports full-second resolution portably, and
		1549	even on systems where the resolution is higher, many filesystems still
		1550	only support whole seconds.
		1551
		1552	That means that, if the time is the only thing that changes, you might
		1553	miss updates: on the first update, C<ev_stat> detects a change and calls
		1554	your callback, which does something. When there is another update within
		1555	the same second, C<ev_stat> will be unable to detect it.
		1556
		1557	The solution to this is to delay acting on a change for a second (or till
		1558	the next second boundary), using a roughly one-second delay C<ev_timer>
		1559	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>
		1560	is added to work around small timing inconsistencies of some operating
		1561	systems.
		1562
		1563	=head3 Watcher-Specific Functions and Data Members
		1564
1313	=over 4	1565	=over 4
1314		1566
1315	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)	1567	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
1316		1568
1317	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)	1569	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)
…		…
1324		1576
1325	The callback will be receive C<EV_STAT> when a change was detected,	1577	The callback will be receive C<EV_STAT> when a change was detected,
1326	relative to the attributes at the time the watcher was started (or the	1578	relative to the attributes at the time the watcher was started (or the
1327	last change was detected).	1579	last change was detected).
1328		1580
1329	=item ev_stat_stat (ev_stat *)	1581	=item ev_stat_stat (loop, ev_stat *)
1330		1582
1331	Updates the stat buffer immediately with new values. If you change the	1583	Updates the stat buffer immediately with new values. If you change the
1332	watched path in your callback, you could call this fucntion to avoid	1584	watched path in your callback, you could call this fucntion to avoid
1333	detecting this change (while introducing a race condition). Can also be	1585	detecting this change (while introducing a race condition). Can also be
1334	useful simply to find out the new values.	1586	useful simply to find out the new values.
…		…
1352	=item const char *path [read-only]	1604	=item const char *path [read-only]
1353		1605
1354	The filesystem path that is being watched.	1606	The filesystem path that is being watched.
1355		1607
1356	=back	1608	=back
		1609
		1610	=head3 Examples
1357		1611
1358	Example: Watch C</etc/passwd> for attribute changes.	1612	Example: Watch C</etc/passwd> for attribute changes.
1359		1613
1360	static void	1614	static void
1361	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1615	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
…		…
1374	}	1628	}
1375		1629
1376	...	1630	...
1377	ev_stat passwd;	1631	ev_stat passwd;
1378		1632
1379	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");	1633	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1380	ev_stat_start (loop, &passwd);	1634	ev_stat_start (loop, &passwd);
		1635
		1636	Example: Like above, but additionally use a one-second delay so we do not
		1637	miss updates (however, frequent updates will delay processing, too, so
		1638	one might do the work both on C<ev_stat> callback invocation I<and> on
		1639	C<ev_timer> callback invocation).
		1640
		1641	static ev_stat passwd;
		1642	static ev_timer timer;
		1643
		1644	static void
		1645	timer_cb (EV_P_ ev_timer *w, int revents)
		1646	{
		1647	ev_timer_stop (EV_A_ w);
		1648
		1649	/* now it's one second after the most recent passwd change */
		1650	}
		1651
		1652	static void
		1653	stat_cb (EV_P_ ev_stat *w, int revents)
		1654	{
		1655	/* reset the one-second timer */
		1656	ev_timer_again (EV_A_ &timer);
		1657	}
		1658
		1659	...
		1660	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
		1661	ev_stat_start (loop, &passwd);
		1662	ev_timer_init (&timer, timer_cb, 0., 1.01);
1381		1663
1382		1664
1383	=head2 C<ev_idle> - when you've got nothing better to do...	1665	=head2 C<ev_idle> - when you've got nothing better to do...
1384		1666
1385	Idle watchers trigger events when no other events of the same or higher	1667	Idle watchers trigger events when no other events of the same or higher
…		…
1399	Apart from keeping your process non-blocking (which is a useful	1681	Apart from keeping your process non-blocking (which is a useful
1400	effect on its own sometimes), idle watchers are a good place to do	1682	effect on its own sometimes), idle watchers are a good place to do
1401	"pseudo-background processing", or delay processing stuff to after the	1683	"pseudo-background processing", or delay processing stuff to after the
1402	event loop has handled all outstanding events.	1684	event loop has handled all outstanding events.
1403		1685
		1686	=head3 Watcher-Specific Functions and Data Members
		1687
1404	=over 4	1688	=over 4
1405		1689
1406	=item ev_idle_init (ev_signal *, callback)	1690	=item ev_idle_init (ev_signal *, callback)
1407		1691
1408	Initialises and configures the idle watcher - it has no parameters of any	1692	Initialises and configures the idle watcher - it has no parameters of any
1409	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1693	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1410	believe me.	1694	believe me.
1411		1695
1412	=back	1696	=back
		1697
		1698	=head3 Examples
1413		1699
1414	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1700	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1415	callback, free it. Also, use no error checking, as usual.	1701	callback, free it. Also, use no error checking, as usual.
1416		1702
1417	static void	1703	static void
1418	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1704	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1419	{	1705	{
1420	free (w);	1706	free (w);
1421	// now do something you wanted to do when the program has	1707	// now do something you wanted to do when the program has
1422	// no longer asnything immediate to do.	1708	// no longer anything immediate to do.
1423	}	1709	}
1424		1710
1425	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1711	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1426	ev_idle_init (idle_watcher, idle_cb);	1712	ev_idle_init (idle_watcher, idle_cb);
1427	ev_idle_start (loop, idle_cb);	1713	ev_idle_start (loop, idle_cb);
…		…
1465	with priority higher than or equal to the event loop and one coroutine	1751	with priority higher than or equal to the event loop and one coroutine
1466	of lower priority, but only once, using idle watchers to keep the event	1752	of lower priority, but only once, using idle watchers to keep the event
1467	loop from blocking if lower-priority coroutines are active, thus mapping	1753	loop from blocking if lower-priority coroutines are active, thus mapping
1468	low-priority coroutines to idle/background tasks).	1754	low-priority coroutines to idle/background tasks).
1469		1755
		1756	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1757	priority, to ensure that they are being run before any other watchers
		1758	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1759	too) should not activate ("feed") events into libev. While libev fully
		1760	supports this, they will be called before other C<ev_check> watchers
		1761	did their job. As C<ev_check> watchers are often used to embed other
		1762	(non-libev) event loops those other event loops might be in an unusable
		1763	state until their C<ev_check> watcher ran (always remind yourself to
		1764	coexist peacefully with others).
		1765
		1766	=head3 Watcher-Specific Functions and Data Members
		1767
1470	=over 4	1768	=over 4
1471		1769
1472	=item ev_prepare_init (ev_prepare *, callback)	1770	=item ev_prepare_init (ev_prepare *, callback)
1473		1771
1474	=item ev_check_init (ev_check *, callback)	1772	=item ev_check_init (ev_check *, callback)
…		…
1477	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1775	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1478	macros, but using them is utterly, utterly and completely pointless.	1776	macros, but using them is utterly, utterly and completely pointless.
1479		1777
1480	=back	1778	=back
1481		1779
1482	Example: To include a library such as adns, you would add IO watchers	1780	=head3 Examples
1483	and a timeout watcher in a prepare handler, as required by libadns, and	1781
		1782	There are a number of principal ways to embed other event loops or modules
		1783	into libev. Here are some ideas on how to include libadns into libev
		1784	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1785	use for an actually working example. Another Perl module named C<EV::Glib>
		1786	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1787	into the Glib event loop).
		1788
		1789	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1484	in a check watcher, destroy them and call into libadns. What follows is	1790	and in a check watcher, destroy them and call into libadns. What follows
1485	pseudo-code only of course:	1791	is pseudo-code only of course. This requires you to either use a low
		1792	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1793	the callbacks for the IO/timeout watchers might not have been called yet.
1486		1794
1487	static ev_io iow [nfd];	1795	static ev_io iow [nfd];
1488	static ev_timer tw;	1796	static ev_timer tw;
1489		1797
1490	static void	1798	static void
1491	io_cb (ev_loop *loop, ev_io *w, int revents)	1799	io_cb (ev_loop *loop, ev_io *w, int revents)
1492	{	1800	{
1493	// set the relevant poll flags
1494	// could also call adns_processreadable etc. here
1495	struct pollfd *fd = (struct pollfd *)w->data;
1496	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1497	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1498	}	1801	}
1499		1802
1500	// create io watchers for each fd and a timer before blocking	1803	// create io watchers for each fd and a timer before blocking
1501	static void	1804	static void
1502	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1805	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
…		…
1508		1811
1509	/* the callback is illegal, but won't be called as we stop during check */	1812	/* the callback is illegal, but won't be called as we stop during check */
1510	ev_timer_init (&tw, 0, timeout * 1e-3);	1813	ev_timer_init (&tw, 0, timeout * 1e-3);
1511	ev_timer_start (loop, &tw);	1814	ev_timer_start (loop, &tw);
1512		1815
1513	// create on ev_io per pollfd	1816	// create one ev_io per pollfd
1514	for (int i = 0; i < nfd; ++i)	1817	for (int i = 0; i < nfd; ++i)
1515	{	1818	{
1516	ev_io_init (iow + i, io_cb, fds [i].fd,	1819	ev_io_init (iow + i, io_cb, fds [i].fd,
1517	((fds [i].events & POLLIN ? EV_READ : 0)	1820	((fds [i].events & POLLIN ? EV_READ : 0)
1518	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1821	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1519		1822
1520	fds [i].revents = 0;	1823	fds [i].revents = 0;
1521	iow [i].data = fds + i;
1522	ev_io_start (loop, iow + i);	1824	ev_io_start (loop, iow + i);
1523	}	1825	}
1524	}	1826	}
1525		1827
1526	// stop all watchers after blocking	1828	// stop all watchers after blocking
…		…
1528	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1830	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1529	{	1831	{
1530	ev_timer_stop (loop, &tw);	1832	ev_timer_stop (loop, &tw);
1531		1833
1532	for (int i = 0; i < nfd; ++i)	1834	for (int i = 0; i < nfd; ++i)
		1835	{
		1836	// set the relevant poll flags
		1837	// could also call adns_processreadable etc. here
		1838	struct pollfd *fd = fds + i;
		1839	int revents = ev_clear_pending (iow + i);
		1840	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1841	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1842
		1843	// now stop the watcher
1533	ev_io_stop (loop, iow + i);	1844	ev_io_stop (loop, iow + i);
		1845	}
1534		1846
1535	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1847	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1848	}
		1849
		1850	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1851	in the prepare watcher and would dispose of the check watcher.
		1852
		1853	Method 3: If the module to be embedded supports explicit event
		1854	notification (adns does), you can also make use of the actual watcher
		1855	callbacks, and only destroy/create the watchers in the prepare watcher.
		1856
		1857	static void
		1858	timer_cb (EV_P_ ev_timer *w, int revents)
		1859	{
		1860	adns_state ads = (adns_state)w->data;
		1861	update_now (EV_A);
		1862
		1863	adns_processtimeouts (ads, &tv_now);
		1864	}
		1865
		1866	static void
		1867	io_cb (EV_P_ ev_io *w, int revents)
		1868	{
		1869	adns_state ads = (adns_state)w->data;
		1870	update_now (EV_A);
		1871
		1872	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1873	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1874	}
		1875
		1876	// do not ever call adns_afterpoll
		1877
		1878	Method 4: Do not use a prepare or check watcher because the module you
		1879	want to embed is too inflexible to support it. Instead, youc na override
		1880	their poll function. The drawback with this solution is that the main
		1881	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1882	this.
		1883
		1884	static gint
		1885	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1886	{
		1887	int got_events = 0;
		1888
		1889	for (n = 0; n < nfds; ++n)
		1890	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1891
		1892	if (timeout >= 0)
		1893	// create/start timer
		1894
		1895	// poll
		1896	ev_loop (EV_A_ 0);
		1897
		1898	// stop timer again
		1899	if (timeout >= 0)
		1900	ev_timer_stop (EV_A_ &to);
		1901
		1902	// stop io watchers again - their callbacks should have set
		1903	for (n = 0; n < nfds; ++n)
		1904	ev_io_stop (EV_A_ iow [n]);
		1905
		1906	return got_events;
1536	}	1907	}
1537		1908
1538		1909
1539	=head2 C<ev_embed> - when one backend isn't enough...	1910	=head2 C<ev_embed> - when one backend isn't enough...
1540		1911
…		…
1583	portable one.	1954	portable one.
1584		1955
1585	So when you want to use this feature you will always have to be prepared	1956	So when you want to use this feature you will always have to be prepared
1586	that you cannot get an embeddable loop. The recommended way to get around	1957	that you cannot get an embeddable loop. The recommended way to get around
1587	this is to have a separate variables for your embeddable loop, try to	1958	this is to have a separate variables for your embeddable loop, try to
1588	create it, and if that fails, use the normal loop for everything:	1959	create it, and if that fails, use the normal loop for everything.
		1960
		1961	=head3 Watcher-Specific Functions and Data Members
		1962
		1963	=over 4
		1964
		1965	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
		1966
		1967	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)
		1968
		1969	Configures the watcher to embed the given loop, which must be
		1970	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
		1971	invoked automatically, otherwise it is the responsibility of the callback
		1972	to invoke it (it will continue to be called until the sweep has been done,
		1973	if you do not want thta, you need to temporarily stop the embed watcher).
		1974
		1975	=item ev_embed_sweep (loop, ev_embed *)
		1976
		1977	Make a single, non-blocking sweep over the embedded loop. This works
		1978	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
		1979	apropriate way for embedded loops.
		1980
		1981	=item struct ev_loop *other [read-only]
		1982
		1983	The embedded event loop.
		1984
		1985	=back
		1986
		1987	=head3 Examples
		1988
		1989	Example: Try to get an embeddable event loop and embed it into the default
		1990	event loop. If that is not possible, use the default loop. The default
		1991	loop is stored in C<loop_hi>, while the mebeddable loop is stored in
		1992	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be
		1993	used).
1589		1994
1590	struct ev_loop *loop_hi = ev_default_init (0);	1995	struct ev_loop *loop_hi = ev_default_init (0);
1591	struct ev_loop *loop_lo = 0;	1996	struct ev_loop *loop_lo = 0;
1592	struct ev_embed embed;	1997	struct ev_embed embed;
1593		1998
…		…
1604	ev_embed_start (loop_hi, &embed);	2009	ev_embed_start (loop_hi, &embed);
1605	}	2010	}
1606	else	2011	else
1607	loop_lo = loop_hi;	2012	loop_lo = loop_hi;
1608		2013
1609	=over 4	2014	Example: Check if kqueue is available but not recommended and create
		2015	a kqueue backend for use with sockets (which usually work with any
		2016	kqueue implementation). Store the kqueue/socket-only event loop in
		2017	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
1610		2018
1611	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)	2019	struct ev_loop *loop = ev_default_init (0);
		2020	struct ev_loop *loop_socket = 0;
		2021	struct ev_embed embed;
		2022
		2023	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
		2024	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
		2025	{
		2026	ev_embed_init (&embed, 0, loop_socket);
		2027	ev_embed_start (loop, &embed);
		2028	}
1612		2029
1613	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	2030	if (!loop_socket)
		2031	loop_socket = loop;
1614		2032
1615	Configures the watcher to embed the given loop, which must be	2033	// now use loop_socket for all sockets, and loop for everything else
1616	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
1617	invoked automatically, otherwise it is the responsibility of the callback
1618	to invoke it (it will continue to be called until the sweep has been done,
1619	if you do not want thta, you need to temporarily stop the embed watcher).
1620
1621	=item ev_embed_sweep (loop, ev_embed *)
1622
1623	Make a single, non-blocking sweep over the embedded loop. This works
1624	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1625	apropriate way for embedded loops.
1626
1627	=item struct ev_loop *loop [read-only]
1628
1629	The embedded event loop.
1630
1631	=back
1632		2034
1633		2035
1634	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2036	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
1635		2037
1636	Fork watchers are called when a C<fork ()> was detected (usually because	2038	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
1639	event loop blocks next and before C<ev_check> watchers are being called,	2041	event loop blocks next and before C<ev_check> watchers are being called,
1640	and only in the child after the fork. If whoever good citizen calling	2042	and only in the child after the fork. If whoever good citizen calling
1641	C<ev_default_fork> cheats and calls it in the wrong process, the fork	2043	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1642	handlers will be invoked, too, of course.	2044	handlers will be invoked, too, of course.
1643		2045
		2046	=head3 Watcher-Specific Functions and Data Members
		2047
1644	=over 4	2048	=over 4
1645		2049
1646	=item ev_fork_init (ev_signal *, callback)	2050	=item ev_fork_init (ev_signal *, callback)
1647		2051
1648	Initialises and configures the fork watcher - it has no parameters of any	2052	Initialises and configures the fork watcher - it has no parameters of any
1649	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	2053	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
1650	believe me.	2054	believe me.
		2055
		2056	=back
		2057
		2058
		2059	=head2 C<ev_async> - how to wake up another event loop
		2060
		2061	In general, you cannot use an C<ev_loop> from multiple threads or other
		2062	asynchronous sources such as signal handlers (as opposed to multiple event
		2063	loops - those are of course safe to use in different threads).
		2064
		2065	Sometimes, however, you need to wake up another event loop you do not
		2066	control, for example because it belongs to another thread. This is what
		2067	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you
		2068	can signal it by calling C<ev_async_send>, which is thread- and signal
		2069	safe.
		2070
		2071	This functionality is very similar to C<ev_signal> watchers, as signals,
		2072	too, are asynchronous in nature, and signals, too, will be compressed
		2073	(i.e. the number of callback invocations may be less than the number of
		2074	C<ev_async_sent> calls).
		2075
		2076	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
		2077	just the default loop.
		2078
		2079	=head3 Queueing
		2080
		2081	C<ev_async> does not support queueing of data in any way. The reason
		2082	is that the author does not know of a simple (or any) algorithm for a
		2083	multiple-writer-single-reader queue that works in all cases and doesn't
		2084	need elaborate support such as pthreads.
		2085
		2086	That means that if you want to queue data, you have to provide your own
		2087	queue. But at least I can tell you would implement locking around your
		2088	queue:
		2089
		2090	=over 4
		2091
		2092	=item queueing from a signal handler context
		2093
		2094	To implement race-free queueing, you simply add to the queue in the signal
		2095	handler but you block the signal handler in the watcher callback. Here is an example that does that for
		2096	some fictitiuous SIGUSR1 handler:
		2097
		2098	static ev_async mysig;
		2099
		2100	static void
		2101	sigusr1_handler (void)
		2102	{
		2103	sometype data;
		2104
		2105	// no locking etc.
		2106	queue_put (data);
		2107	ev_async_send (EV_DEFAULT_ &mysig);
		2108	}
		2109
		2110	static void
		2111	mysig_cb (EV_P_ ev_async *w, int revents)
		2112	{
		2113	sometype data;
		2114	sigset_t block, prev;
		2115
		2116	sigemptyset (&block);
		2117	sigaddset (&block, SIGUSR1);
		2118	sigprocmask (SIG_BLOCK, &block, &prev);
		2119
		2120	while (queue_get (&data))
		2121	process (data);
		2122
		2123	if (sigismember (&prev, SIGUSR1)
		2124	sigprocmask (SIG_UNBLOCK, &block, 0);
		2125	}
		2126
		2127	(Note: pthreads in theory requires you to use C<pthread_setmask>
		2128	instead of C<sigprocmask> when you use threads, but libev doesn't do it
		2129	either...).
		2130
		2131	=item queueing from a thread context
		2132
		2133	The strategy for threads is different, as you cannot (easily) block
		2134	threads but you can easily preempt them, so to queue safely you need to
		2135	employ a traditional mutex lock, such as in this pthread example:
		2136
		2137	static ev_async mysig;
		2138	static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER;
		2139
		2140	static void
		2141	otherthread (void)
		2142	{
		2143	// only need to lock the actual queueing operation
		2144	pthread_mutex_lock (&mymutex);
		2145	queue_put (data);
		2146	pthread_mutex_unlock (&mymutex);
		2147
		2148	ev_async_send (EV_DEFAULT_ &mysig);
		2149	}
		2150
		2151	static void
		2152	mysig_cb (EV_P_ ev_async *w, int revents)
		2153	{
		2154	pthread_mutex_lock (&mymutex);
		2155
		2156	while (queue_get (&data))
		2157	process (data);
		2158
		2159	pthread_mutex_unlock (&mymutex);
		2160	}
		2161
		2162	=back
		2163
		2164
		2165	=head3 Watcher-Specific Functions and Data Members
		2166
		2167	=over 4
		2168
		2169	=item ev_async_init (ev_async *, callback)
		2170
		2171	Initialises and configures the async watcher - it has no parameters of any
		2172	kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless,
		2173	believe me.
		2174
		2175	=item ev_async_send (loop, ev_async *)
		2176
		2177	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
		2178	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
		2179	C<ev_feed_event>, this call is safe to do in other threads, signal or
		2180	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding
		2181	section below on what exactly this means).
		2182
		2183	This call incurs the overhead of a syscall only once per loop iteration,
		2184	so while the overhead might be noticable, it doesn't apply to repeated
		2185	calls to C<ev_async_send>.
1651		2186
1652	=back	2187	=back
1653		2188
1654		2189
1655	=head1 OTHER FUNCTIONS	2190	=head1 OTHER FUNCTIONS
…		…
1749	This automatically includes F<ev.h> and puts all of its definitions (many	2284	This automatically includes F<ev.h> and puts all of its definitions (many
1750	of them macros) into the global namespace. All C++ specific things are	2285	of them macros) into the global namespace. All C++ specific things are
1751	put into the C<ev> namespace. It should support all the same embedding	2286	put into the C<ev> namespace. It should support all the same embedding
1752	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2287	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1753		2288
1754	Care has been taken to keep the overhead low. The only data member added	2289	Care has been taken to keep the overhead low. The only data member the C++
1755	to the C-style watchers is the event loop the watcher is associated with	2290	classes add (compared to plain C-style watchers) is the event loop pointer
1756	(or no additional members at all if you disable C<EV_MULTIPLICITY> when	2291	that the watcher is associated with (or no additional members at all if
1757	embedding libev).	2292	you disable C<EV_MULTIPLICITY> when embedding libev).
1758		2293
1759	Currently, functions and static and non-static member functions can be	2294	Currently, functions, and static and non-static member functions can be
1760	used as callbacks. Other types should be easy to add as long as they only	2295	used as callbacks. Other types should be easy to add as long as they only
1761	need one additional pointer for context. If you need support for other	2296	need one additional pointer for context. If you need support for other
1762	types of functors please contact the author (preferably after implementing	2297	types of functors please contact the author (preferably after implementing
1763	it).	2298	it).
1764		2299
…		…
1828		2363
1829	myclass obj;	2364	myclass obj;
1830	ev::io iow;	2365	ev::io iow;
1831	iow.set <myclass, &myclass::io_cb> (&obj);	2366	iow.set <myclass, &myclass::io_cb> (&obj);
1832		2367
1833	=item w->set (void (*function)(watcher &w, int), void *data = 0)	2368	=item w->set<function> (void *data = 0)
1834		2369
1835	Also sets a callback, but uses a static method or plain function as	2370	Also sets a callback, but uses a static method or plain function as
1836	callback. The optional C<data> argument will be stored in the watcher's	2371	callback. The optional C<data> argument will be stored in the watcher's
1837	C<data> member and is free for you to use.	2372	C<data> member and is free for you to use.
1838		2373
		2374	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2375
1839	See the method-C<set> above for more details.	2376	See the method-C<set> above for more details.
		2377
		2378	Example:
		2379
		2380	static void io_cb (ev::io &w, int revents) { }
		2381	iow.set <io_cb> ();
1840		2382
1841	=item w->set (struct ev_loop *)	2383	=item w->set (struct ev_loop *)
1842		2384
1843	Associates a different C<struct ev_loop> with this watcher. You can only	2385	Associates a different C<struct ev_loop> with this watcher. You can only
1844	do this when the watcher is inactive (and not pending either).	2386	do this when the watcher is inactive (and not pending either).
…		…
1857		2399
1858	=item w->stop ()	2400	=item w->stop ()
1859		2401
1860	Stops the watcher if it is active. Again, no C<loop> argument.	2402	Stops the watcher if it is active. Again, no C<loop> argument.
1861		2403
1862	=item w->again () C<ev::timer>, C<ev::periodic> only	2404	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1863		2405
1864	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2406	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1865	C<ev_TYPE_again> function.	2407	C<ev_TYPE_again> function.
1866		2408
1867	=item w->sweep () C<ev::embed> only	2409	=item w->sweep () (C<ev::embed> only)
1868		2410
1869	Invokes C<ev_embed_sweep>.	2411	Invokes C<ev_embed_sweep>.
1870		2412
1871	=item w->update () C<ev::stat> only	2413	=item w->update () (C<ev::stat> only)
1872		2414
1873	Invokes C<ev_stat_stat>.	2415	Invokes C<ev_stat_stat>.
1874		2416
1875	=back	2417	=back
1876		2418
…		…
1879	Example: Define a class with an IO and idle watcher, start one of them in	2421	Example: Define a class with an IO and idle watcher, start one of them in
1880	the constructor.	2422	the constructor.
1881		2423
1882	class myclass	2424	class myclass
1883	{	2425	{
1884	ev_io io; void io_cb (ev::io &w, int revents);	2426	ev::io io; void io_cb (ev::io &w, int revents);
1885	ev_idle idle void idle_cb (ev::idle &w, int revents);	2427	ev:idle idle void idle_cb (ev::idle &w, int revents);
1886		2428
1887	myclass ();	2429	myclass (int fd)
1888	}
1889
1890	myclass::myclass (int fd)
1891	{	2430	{
1892	io .set <myclass, &myclass::io_cb > (this);	2431	io .set <myclass, &myclass::io_cb > (this);
1893	idle.set <myclass, &myclass::idle_cb> (this);	2432	idle.set <myclass, &myclass::idle_cb> (this);
1894		2433
1895	io.start (fd, ev::READ);	2434	io.start (fd, ev::READ);
		2435	}
1896	}	2436	};
1897		2437
1898		2438
1899	=head1 MACRO MAGIC	2439	=head1 MACRO MAGIC
1900		2440
1901	Libev can be compiled with a variety of options, the most fundemantal is	2441	Libev can be compiled with a variety of options, the most fundamantal
1902	C<EV_MULTIPLICITY>. This option determines whether (most) functions and	2442	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1903	callbacks have an initial C<struct ev_loop *> argument.	2443	functions and callbacks have an initial C<struct ev_loop *> argument.
1904		2444
1905	To make it easier to write programs that cope with either variant, the	2445	To make it easier to write programs that cope with either variant, the
1906	following macros are defined:	2446	following macros are defined:
1907		2447
1908	=over 4	2448	=over 4
…		…
1962	Libev can (and often is) directly embedded into host	2502	Libev can (and often is) directly embedded into host
1963	applications. Examples of applications that embed it include the Deliantra	2503	applications. Examples of applications that embed it include the Deliantra
1964	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2504	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1965	and rxvt-unicode.	2505	and rxvt-unicode.
1966		2506
1967	The goal is to enable you to just copy the neecssary files into your	2507	The goal is to enable you to just copy the necessary files into your
1968	source directory without having to change even a single line in them, so	2508	source directory without having to change even a single line in them, so
1969	you can easily upgrade by simply copying (or having a checked-out copy of	2509	you can easily upgrade by simply copying (or having a checked-out copy of
1970	libev somewhere in your source tree).	2510	libev somewhere in your source tree).
1971		2511
1972	=head2 FILESETS	2512	=head2 FILESETS
…		…
2062		2602
2063	If defined to be C<1>, libev will try to detect the availability of the	2603	If defined to be C<1>, libev will try to detect the availability of the
2064	monotonic clock option at both compiletime and runtime. Otherwise no use	2604	monotonic clock option at both compiletime and runtime. Otherwise no use
2065	of the monotonic clock option will be attempted. If you enable this, you	2605	of the monotonic clock option will be attempted. If you enable this, you
2066	usually have to link against librt or something similar. Enabling it when	2606	usually have to link against librt or something similar. Enabling it when
2067	the functionality isn't available is safe, though, althoguh you have	2607	the functionality isn't available is safe, though, although you have
2068	to make sure you link against any libraries where the C<clock_gettime>	2608	to make sure you link against any libraries where the C<clock_gettime>
2069	function is hiding in (often F<-lrt>).	2609	function is hiding in (often F<-lrt>).
2070		2610
2071	=item EV_USE_REALTIME	2611	=item EV_USE_REALTIME
2072		2612
2073	If defined to be C<1>, libev will try to detect the availability of the	2613	If defined to be C<1>, libev will try to detect the availability of the
2074	realtime clock option at compiletime (and assume its availability at	2614	realtime clock option at compiletime (and assume its availability at
2075	runtime if successful). Otherwise no use of the realtime clock option will	2615	runtime if successful). Otherwise no use of the realtime clock option will
2076	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2616	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2077	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2617	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2078	in the description of C<EV_USE_MONOTONIC>, though.	2618	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
		2619
		2620	=item EV_USE_NANOSLEEP
		2621
		2622	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
		2623	and will use it for delays. Otherwise it will use C<select ()>.
2079		2624
2080	=item EV_USE_SELECT	2625	=item EV_USE_SELECT
2081		2626
2082	If undefined or defined to be C<1>, libev will compile in support for the	2627	If undefined or defined to be C<1>, libev will compile in support for the
2083	C<select>(2) backend. No attempt at autodetection will be done: if no	2628	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
2101	wants osf handles on win32 (this is the case when the select to	2646	wants osf handles on win32 (this is the case when the select to
2102	be used is the winsock select). This means that it will call	2647	be used is the winsock select). This means that it will call
2103	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	2648	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
2104	it is assumed that all these functions actually work on fds, even	2649	it is assumed that all these functions actually work on fds, even
2105	on win32. Should not be defined on non-win32 platforms.	2650	on win32. Should not be defined on non-win32 platforms.
		2651
		2652	=item EV_FD_TO_WIN32_HANDLE
		2653
		2654	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
		2655	file descriptors to socket handles. When not defining this symbol (the
		2656	default), then libev will call C<_get_osfhandle>, which is usually
		2657	correct. In some cases, programs use their own file descriptor management,
		2658	in which case they can provide this function to map fds to socket handles.
2106		2659
2107	=item EV_USE_POLL	2660	=item EV_USE_POLL
2108		2661
2109	If defined to be C<1>, libev will compile in support for the C<poll>(2)	2662	If defined to be C<1>, libev will compile in support for the C<poll>(2)
2110	backend. Otherwise it will be enabled on non-win32 platforms. It	2663	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
2144		2697
2145	If defined to be C<1>, libev will compile in support for the Linux inotify	2698	If defined to be C<1>, libev will compile in support for the Linux inotify
2146	interface to speed up C<ev_stat> watchers. Its actual availability will	2699	interface to speed up C<ev_stat> watchers. Its actual availability will
2147	be detected at runtime.	2700	be detected at runtime.
2148		2701
		2702	=item EV_ATOMIC_T
		2703
		2704	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
		2705	access is atomic with respect to other threads or signal contexts. No such
		2706	type is easily found in the C language, so you can provide your own type
		2707	that you know is safe for your purposes. It is used both for signal handler "locking"
		2708	as well as for signal and thread safety in C<ev_async> watchers.
		2709
		2710	In the absense of this define, libev will use C<sig_atomic_t volatile>
		2711	(from F<signal.h>), which is usually good enough on most platforms.
		2712
2149	=item EV_H	2713	=item EV_H
2150		2714
2151	The name of the F<ev.h> header file used to include it. The default if	2715	The name of the F<ev.h> header file used to include it. The default if
2152	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2716	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
2153	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2717	used to virtually rename the F<ev.h> header file in case of conflicts.
2154		2718
2155	=item EV_CONFIG_H	2719	=item EV_CONFIG_H
2156		2720
2157	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	2721	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
2158	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	2722	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
2159	C<EV_H>, above.	2723	C<EV_H>, above.
2160		2724
2161	=item EV_EVENT_H	2725	=item EV_EVENT_H
2162		2726
2163	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	2727	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
2164	of how the F<event.h> header can be found.	2728	of how the F<event.h> header can be found, the default is C<"event.h">.
2165		2729
2166	=item EV_PROTOTYPES	2730	=item EV_PROTOTYPES
2167		2731
2168	If defined to be C<0>, then F<ev.h> will not define any function	2732	If defined to be C<0>, then F<ev.h> will not define any function
2169	prototypes, but still define all the structs and other symbols. This is	2733	prototypes, but still define all the structs and other symbols. This is
…		…
2220	=item EV_FORK_ENABLE	2784	=item EV_FORK_ENABLE
2221		2785
2222	If undefined or defined to be C<1>, then fork watchers are supported. If	2786	If undefined or defined to be C<1>, then fork watchers are supported. If
2223	defined to be C<0>, then they are not.	2787	defined to be C<0>, then they are not.
2224		2788
		2789	=item EV_ASYNC_ENABLE
		2790
		2791	If undefined or defined to be C<1>, then async watchers are supported. If
		2792	defined to be C<0>, then they are not.
		2793
2225	=item EV_MINIMAL	2794	=item EV_MINIMAL
2226		2795
2227	If you need to shave off some kilobytes of code at the expense of some	2796	If you need to shave off some kilobytes of code at the expense of some
2228	speed, define this symbol to C<1>. Currently only used for gcc to override	2797	speed, define this symbol to C<1>. Currently only used for gcc to override
2229	some inlining decisions, saves roughly 30% codesize of amd64.	2798	some inlining decisions, saves roughly 30% codesize of amd64.
…		…
2235	than enough. If you need to manage thousands of children you might want to	2804	than enough. If you need to manage thousands of children you might want to
2236	increase this value (I<must> be a power of two).	2805	increase this value (I<must> be a power of two).
2237		2806
2238	=item EV_INOTIFY_HASHSIZE	2807	=item EV_INOTIFY_HASHSIZE
2239		2808
2240	C<ev_staz> watchers use a small hash table to distribute workload by	2809	C<ev_stat> watchers use a small hash table to distribute workload by
2241	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	2810	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2242	usually more than enough. If you need to manage thousands of C<ev_stat>	2811	usually more than enough. If you need to manage thousands of C<ev_stat>
2243	watchers you might want to increase this value (I<must> be a power of	2812	watchers you might want to increase this value (I<must> be a power of
2244	two).	2813	two).
2245		2814
…		…
2262		2831
2263	=item ev_set_cb (ev, cb)	2832	=item ev_set_cb (ev, cb)
2264		2833
2265	Can be used to change the callback member declaration in each watcher,	2834	Can be used to change the callback member declaration in each watcher,
2266	and the way callbacks are invoked and set. Must expand to a struct member	2835	and the way callbacks are invoked and set. Must expand to a struct member
2267	definition and a statement, respectively. See the F<ev.v> header file for	2836	definition and a statement, respectively. See the F<ev.h> header file for
2268	their default definitions. One possible use for overriding these is to	2837	their default definitions. One possible use for overriding these is to
2269	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2838	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2270	method calls instead of plain function calls in C++.	2839	method calls instead of plain function calls in C++.
		2840
		2841	=head2 EXPORTED API SYMBOLS
		2842
		2843	If you need to re-export the API (e.g. via a dll) and you need a list of
		2844	exported symbols, you can use the provided F<Symbol.*> files which list
		2845	all public symbols, one per line:
		2846
		2847	Symbols.ev for libev proper
		2848	Symbols.event for the libevent emulation
		2849
		2850	This can also be used to rename all public symbols to avoid clashes with
		2851	multiple versions of libev linked together (which is obviously bad in
		2852	itself, but sometimes it is inconvinient to avoid this).
		2853
		2854	A sed command like this will create wrapper C<#define>'s that you need to
		2855	include before including F<ev.h>:
		2856
		2857	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2858
		2859	This would create a file F<wrap.h> which essentially looks like this:
		2860
		2861	#define ev_backend myprefix_ev_backend
		2862	#define ev_check_start myprefix_ev_check_start
		2863	#define ev_check_stop myprefix_ev_check_stop
		2864	...
2271		2865
2272	=head2 EXAMPLES	2866	=head2 EXAMPLES
2273		2867
2274	For a real-world example of a program the includes libev	2868	For a real-world example of a program the includes libev
2275	verbatim, you can have a look at the EV perl module	2869	verbatim, you can have a look at the EV perl module
…		…
2316		2910
2317	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2911	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2318		2912
2319	This means that, when you have a watcher that triggers in one hour and	2913	This means that, when you have a watcher that triggers in one hour and
2320	there are 100 watchers that would trigger before that then inserting will	2914	there are 100 watchers that would trigger before that then inserting will
2321	have to skip those 100 watchers.	2915	have to skip roughly seven (C<ld 100>) of these watchers.
2322		2916
2323	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2917	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
2324		2918
2325	That means that for changing a timer costs less than removing/adding them	2919	That means that changing a timer costs less than removing/adding them
2326	as only the relative motion in the event queue has to be paid for.	2920	as only the relative motion in the event queue has to be paid for.
2327		2921
2328	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2922	=item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)
2329		2923
2330	These just add the watcher into an array or at the head of a list.	2924	These just add the watcher into an array or at the head of a list.
		2925
2331	=item Stopping check/prepare/idle watchers: O(1)	2926	=item Stopping check/prepare/idle/fork/async watchers: O(1)
2332		2927
2333	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2928	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2334		2929
2335	These watchers are stored in lists then need to be walked to find the	2930	These watchers are stored in lists then need to be walked to find the
2336	correct watcher to remove. The lists are usually short (you don't usually	2931	correct watcher to remove. The lists are usually short (you don't usually
2337	have many watchers waiting for the same fd or signal).	2932	have many watchers waiting for the same fd or signal).
2338		2933
2339	=item Finding the next timer per loop iteration: O(1)	2934	=item Finding the next timer in each loop iteration: O(1)
		2935
		2936	By virtue of using a binary heap, the next timer is always found at the
		2937	beginning of the storage array.
2340		2938
2341	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2939	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2342		2940
2343	A change means an I/O watcher gets started or stopped, which requires	2941	A change means an I/O watcher gets started or stopped, which requires
2344	libev to recalculate its status (and possibly tell the kernel).	2942	libev to recalculate its status (and possibly tell the kernel, depending
		2943	on backend and wether C<ev_io_set> was used).
2345		2944
2346	=item Activating one watcher: O(1)	2945	=item Activating one watcher (putting it into the pending state): O(1)
2347		2946
2348	=item Priority handling: O(number_of_priorities)	2947	=item Priority handling: O(number_of_priorities)
2349		2948
2350	Priorities are implemented by allocating some space for each	2949	Priorities are implemented by allocating some space for each
2351	priority. When doing priority-based operations, libev usually has to	2950	priority. When doing priority-based operations, libev usually has to
2352	linearly search all the priorities.	2951	linearly search all the priorities, but starting/stopping and activating
		2952	watchers becomes O(1) w.r.t. priority handling.
		2953
		2954	=item Sending an ev_async: O(1)
		2955
		2956	=item Processing ev_async_send: O(number_of_async_watchers)
		2957
		2958	=item Processing signals: O(max_signal_number)
		2959
		2960	Sending involves a syscall I<iff> there were no other C<ev_async_send>
		2961	calls in the current loop iteration. Checking for async and signal events
		2962	involves iterating over all running async watchers or all signal numbers.
2353		2963
2354	=back	2964	=back
2355		2965
2356		2966
		2967	=head1 Win32 platform limitations and workarounds
		2968
		2969	Win32 doesn't support any of the standards (e.g. POSIX) that libev
		2970	requires, and its I/O model is fundamentally incompatible with the POSIX
		2971	model. Libev still offers limited functionality on this platform in
		2972	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
		2973	descriptors. This only applies when using Win32 natively, not when using
		2974	e.g. cygwin.
		2975
		2976	There is no supported compilation method available on windows except
		2977	embedding it into other applications.
		2978
		2979	Due to the many, low, and arbitrary limits on the win32 platform and the
		2980	abysmal performance of winsockets, using a large number of sockets is not
		2981	recommended (and not reasonable). If your program needs to use more than
		2982	a hundred or so sockets, then likely it needs to use a totally different
		2983	implementation for windows, as libev offers the POSIX model, which cannot
		2984	be implemented efficiently on windows (microsoft monopoly games).
		2985
		2986	=over 4
		2987
		2988	=item The winsocket select function
		2989
		2990	The winsocket C<select> function doesn't follow POSIX in that it requires
		2991	socket I<handles> and not socket I<file descriptors>. This makes select
		2992	very inefficient, and also requires a mapping from file descriptors
		2993	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,
		2994	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor
		2995	symbols for more info.
		2996
		2997	The configuration for a "naked" win32 using the microsoft runtime
		2998	libraries and raw winsocket select is:
		2999
		3000	#define EV_USE_SELECT 1
		3001	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
		3002
		3003	Note that winsockets handling of fd sets is O(n), so you can easily get a
		3004	complexity in the O(n²) range when using win32.
		3005
		3006	=item Limited number of file descriptors
		3007
		3008	Windows has numerous arbitrary (and low) limits on things. Early versions
		3009	of winsocket's select only supported waiting for a max. of C<64> handles
		3010	(probably owning to the fact that all windows kernels can only wait for
		3011	C<64> things at the same time internally; microsoft recommends spawning a
		3012	chain of threads and wait for 63 handles and the previous thread in each).
		3013
		3014	Newer versions support more handles, but you need to define C<FD_SETSIZE>
		3015	to some high number (e.g. C<2048>) before compiling the winsocket select
		3016	call (which might be in libev or elsewhere, for example, perl does its own
		3017	select emulation on windows).
		3018
		3019	Another limit is the number of file descriptors in the microsoft runtime
		3020	libraries, which by default is C<64> (there must be a hidden I<64> fetish
		3021	or something like this inside microsoft). You can increase this by calling
		3022	C<_setmaxstdio>, which can increase this limit to C<2048> (another
		3023	arbitrary limit), but is broken in many versions of the microsoft runtime
		3024	libraries.
		3025
		3026	This might get you to about C<512> or C<2048> sockets (depending on
		3027	windows version and/or the phase of the moon). To get more, you need to
		3028	wrap all I/O functions and provide your own fd management, but the cost of
		3029	calling select (O(n²)) will likely make this unworkable.
		3030
		3031	=back
		3032
		3033
2357	=head1 AUTHOR	3034	=head1 AUTHOR
2358		3035
2359	Marc Lehmann <libev@schmorp.de>.	3036	Marc Lehmann <libev@schmorp.de>.
2360		3037

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