ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.74 by root, Sat Dec 8 14:12:08 2007 UTC vs.
Revision 1.133 by root, Sun Feb 24 06:50:16 2008 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head1 EXAMPLE PROGRAM	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
…		…
655		777
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>).
		782
		783	=item C<EV_ASYNC>
		784
		785	The given async watcher has been asynchronously notified (see C<ev_async>).
660		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
…		…
882	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
883	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
884	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
885	required if you know what you are doing).	1011	required if you know what you are doing).
886		1012
887	You have to be careful with dup'ed file descriptors, though. Some backends
888	(the linux epoll backend is a notable example) cannot handle dup'ed file
889	descriptors correctly if you register interest in two or more fds pointing
890	to the same underlying file/socket/etc. description (that is, they share
891	the same underlying "file open").
892
893	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
894	(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
895	C<EVBACKEND_POLL>).	1015	C<EVBACKEND_POLL>).
896		1016
897	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
…		…
907	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
908	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
909	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
910	its own, so its quite safe to use).	1030	its own, so its quite safe to use).
911		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
912	=over 4	1078	=over 4
913		1079
914	=item ev_io_init (ev_io *, callback, int fd, int events)	1080	=item ev_io_init (ev_io *, callback, int fd, int events)
915		1081
916	=item ev_io_set (ev_io *, int fd, int events)	1082	=item ev_io_set (ev_io *, int fd, int events)
…		…
926	=item int events [read-only]	1092	=item int events [read-only]
927		1093
928	The events being watched.	1094	The events being watched.
929		1095
930	=back	1096	=back
		1097
		1098	=head3 Examples
931		1099
932	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
933	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
934	attempt to read a whole line in the callback.	1102	attempt to read a whole line in the callback.
935		1103
…		…
969		1137
970	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,
971	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
972	order of execution is undefined.	1140	order of execution is undefined.
973		1141
		1142	=head3 Watcher-Specific Functions and Data Members
		1143
974	=over 4	1144	=over 4
975		1145
976	=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)
977		1147
978	=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)
…		…
986	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
987	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
988	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
989	timer will not fire more than once per event loop iteration.	1159	timer will not fire more than once per event loop iteration.
990		1160
991	=item ev_timer_again (loop)	1161	=item ev_timer_again (loop, ev_timer *)
992		1162
993	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
994	repeating. The exact semantics are:	1164	repeating. The exact semantics are:
995		1165
996	If the timer is pending, its pending status is cleared.	1166	If the timer is pending, its pending status is cleared.
…		…
1031	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),
1032	which is also when any modifications are taken into account.	1202	which is also when any modifications are taken into account.
1033		1203
1034	=back	1204	=back
1035		1205
		1206	=head3 Examples
		1207
1036	Example: Create a timer that fires after 60 seconds.	1208	Example: Create a timer that fires after 60 seconds.
1037		1209
1038	static void	1210	static void
1039	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)
1040	{	1212	{
…		…
1073	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
1074	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
1075	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 ()
1076	+ 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
1077	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
1078	roughly 10 seconds later and of course not if you reset your system time	1250	roughly 10 seconds later).
1079	again).
1080		1251
1081	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
1082	triggering an event on eahc midnight, local time.	1253	triggering an event on each midnight, local time or other, complicated,
		1254	rules.
1083		1255
1084	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
1085	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
1086	during the same loop iteration then order of execution is undefined.	1258	during the same loop iteration then order of execution is undefined.
1087		1259
		1260	=head3 Watcher-Specific Functions and Data Members
		1261
1088	=over 4	1262	=over 4
1089		1263
1090	=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)
1091		1265
1092	=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)
…		…
1094	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
1095	operation, and we will explain them from simplest to complex:	1269	operation, and we will explain them from simplest to complex:
1096		1270
1097	=over 4	1271	=over 4
1098		1272
1099	=item * absolute timer (interval = reschedule_cb = 0)	1273	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1100		1274
1101	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
1102	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,
1103	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
1104	system time reaches or surpasses this time.	1278	system time reaches or surpasses this time.
1105		1279
1106	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1280	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1107		1281
1108	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
1109	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)
1110	of any time jumps.	1284	and then repeat, regardless of any time jumps.
1111		1285
1112	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
1113	time:	1287	time:
1114		1288
1115	ev_periodic_set (&periodic, 0., 3600., 0);	1289	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1121		1295
1122	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
1123	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
1124	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.
1125		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
1126	=item * manual reschedule mode (reschedule_cb = callback)	1304	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1127		1305
1128	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
1129	ignored. Instead, each time the periodic watcher gets scheduled, the	1307	ignored. Instead, each time the periodic watcher gets scheduled, the
1130	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
1131	current time as second argument.	1309	current time as second argument.
1132		1310
1133	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,
1134	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,
1135	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
1136	starting a prepare watcher).	1314	starting an C<ev_prepare> watcher, which is legal).
1137		1315
1138	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,
1139	ev_tstamp now)>, e.g.:	1317	ev_tstamp now)>, e.g.:
1140		1318
1141	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)
…		…
1164	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
1165	when you changed some parameters or the reschedule callback would return	1343	when you changed some parameters or the reschedule callback would return
1166	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
1167	program when the crontabs have changed).	1345	program when the crontabs have changed).
1168		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
1169	=item ev_tstamp interval [read-write]	1355	=item ev_tstamp interval [read-write]
1170		1356
1171	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
1172	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
1173	called.	1359	called.
…		…
1176		1362
1177	The current reschedule callback, or C<0>, if this functionality is	1363	The current reschedule callback, or C<0>, if this functionality is
1178	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
1179	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.
1180		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
1181	=back	1372	=back
		1373
		1374	=head3 Examples
1182		1375
1183	Example: Call a callback every hour, or, more precisely, whenever the	1376	Example: Call a callback every hour, or, more precisely, whenever the
1184	system clock is divisible by 3600. The callback invocation times have	1377	system clock is divisible by 3600. The callback invocation times have
1185	potentially a lot of jittering, but good long-term stability.	1378	potentially a lot of jittering, but good long-term stability.
1186		1379
…		…
1226	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
1227	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
1228	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
1229	SIG_DFL (regardless of what it was set to before).	1422	SIG_DFL (regardless of what it was set to before).
1230		1423
		1424	=head3 Watcher-Specific Functions and Data Members
		1425
1231	=over 4	1426	=over 4
1232		1427
1233	=item ev_signal_init (ev_signal *, callback, int signum)	1428	=item ev_signal_init (ev_signal *, callback, int signum)
1234		1429
1235	=item ev_signal_set (ev_signal *, int signum)	1430	=item ev_signal_set (ev_signal *, int signum)
…		…
1241		1436
1242	The signal the watcher watches out for.	1437	The signal the watcher watches out for.
1243		1438
1244	=back	1439	=back
1245		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
1246		1455
1247	=head2 C<ev_child> - watch out for process status changes	1456	=head2 C<ev_child> - watch out for process status changes
1248		1457
1249	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
1250	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).
1251		1460
		1461	=head3 Watcher-Specific Functions and Data Members
		1462
1252	=over 4	1463	=over 4
1253		1464
1254	=item ev_child_init (ev_child *, callback, int pid)	1465	=item ev_child_init (ev_child *, callback, int pid, int trace)
1255		1466
1256	=item ev_child_set (ev_child *, int pid)	1467	=item ev_child_set (ev_child *, int pid, int trace)
1257		1468
1258	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
1259	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
1260	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
1261	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
1262	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
1263	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).
1264		1477
1265	=item int pid [read-only]	1478	=item int pid [read-only]
1266		1479
1267	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.
1268		1481
…		…
1274		1487
1275	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
1276	C<waitpid> and C<sys/wait.h> documentation for details).	1489	C<waitpid> and C<sys/wait.h> documentation for details).
1277		1490
1278	=back	1491	=back
1279
1280	Example: Try to exit cleanly on SIGINT and SIGTERM.
1281
1282	static void
1283	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1284	{
1285	ev_unloop (loop, EVUNLOOP_ALL);
1286	}
1287
1288	struct ev_signal signal_watcher;
1289	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1290	ev_signal_start (loop, &sigint_cb);
1291		1492
1292		1493
1293	=head2 C<ev_stat> - did the file attributes just change?	1494	=head2 C<ev_stat> - did the file attributes just change?
1294		1495
1295	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
…		…
1324	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
1325	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
1326	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
1327	polling.	1528	polling.
1328		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
1329	=over 4	1565	=over 4
1330		1566
1331	=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)
1332		1568
1333	=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)
…		…
1340		1576
1341	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,
1342	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
1343	last change was detected).	1579	last change was detected).
1344		1580
1345	=item ev_stat_stat (ev_stat *)	1581	=item ev_stat_stat (loop, ev_stat *)
1346		1582
1347	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
1348	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
1349	detecting this change (while introducing a race condition). Can also be	1585	detecting this change (while introducing a race condition). Can also be
1350	useful simply to find out the new values.	1586	useful simply to find out the new values.
…		…
1368	=item const char *path [read-only]	1604	=item const char *path [read-only]
1369		1605
1370	The filesystem path that is being watched.	1606	The filesystem path that is being watched.
1371		1607
1372	=back	1608	=back
		1609
		1610	=head3 Examples
1373		1611
1374	Example: Watch C</etc/passwd> for attribute changes.	1612	Example: Watch C</etc/passwd> for attribute changes.
1375		1613
1376	static void	1614	static void
1377	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1615	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
…		…
1390	}	1628	}
1391		1629
1392	...	1630	...
1393	ev_stat passwd;	1631	ev_stat passwd;
1394		1632
1395	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");	1633	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1396	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);
1397		1663
1398		1664
1399	=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...
1400		1666
1401	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
…		…
1415	Apart from keeping your process non-blocking (which is a useful	1681	Apart from keeping your process non-blocking (which is a useful
1416	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
1417	"pseudo-background processing", or delay processing stuff to after the	1683	"pseudo-background processing", or delay processing stuff to after the
1418	event loop has handled all outstanding events.	1684	event loop has handled all outstanding events.
1419		1685
		1686	=head3 Watcher-Specific Functions and Data Members
		1687
1420	=over 4	1688	=over 4
1421		1689
1422	=item ev_idle_init (ev_signal *, callback)	1690	=item ev_idle_init (ev_signal *, callback)
1423		1691
1424	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
1425	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,
1426	believe me.	1694	believe me.
1427		1695
1428	=back	1696	=back
		1697
		1698	=head3 Examples
1429		1699
1430	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
1431	callback, free it. Also, use no error checking, as usual.	1701	callback, free it. Also, use no error checking, as usual.
1432		1702
1433	static void	1703	static void
1434	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)
1435	{	1705	{
1436	free (w);	1706	free (w);
1437	// now do something you wanted to do when the program has	1707	// now do something you wanted to do when the program has
1438	// no longer asnything immediate to do.	1708	// no longer anything immediate to do.
1439	}	1709	}
1440		1710
1441	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1711	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1442	ev_idle_init (idle_watcher, idle_cb);	1712	ev_idle_init (idle_watcher, idle_cb);
1443	ev_idle_start (loop, idle_cb);	1713	ev_idle_start (loop, idle_cb);
…		…
1481	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
1482	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
1483	loop from blocking if lower-priority coroutines are active, thus mapping	1753	loop from blocking if lower-priority coroutines are active, thus mapping
1484	low-priority coroutines to idle/background tasks).	1754	low-priority coroutines to idle/background tasks).
1485		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
1486	=over 4	1768	=over 4
1487		1769
1488	=item ev_prepare_init (ev_prepare *, callback)	1770	=item ev_prepare_init (ev_prepare *, callback)
1489		1771
1490	=item ev_check_init (ev_check *, callback)	1772	=item ev_check_init (ev_check *, callback)
…		…
1493	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>
1494	macros, but using them is utterly, utterly and completely pointless.	1776	macros, but using them is utterly, utterly and completely pointless.
1495		1777
1496	=back	1778	=back
1497		1779
1498	Example: To include a library such as adns, you would add IO watchers	1780	=head3 Examples
1499	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,
1500	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
1501	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.
1502		1794
1503	static ev_io iow [nfd];	1795	static ev_io iow [nfd];
1504	static ev_timer tw;	1796	static ev_timer tw;
1505		1797
1506	static void	1798	static void
1507	io_cb (ev_loop *loop, ev_io *w, int revents)	1799	io_cb (ev_loop *loop, ev_io *w, int revents)
1508	{	1800	{
1509	// set the relevant poll flags
1510	// could also call adns_processreadable etc. here
1511	struct pollfd *fd = (struct pollfd *)w->data;
1512	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1513	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1514	}	1801	}
1515		1802
1516	// create io watchers for each fd and a timer before blocking	1803	// create io watchers for each fd and a timer before blocking
1517	static void	1804	static void
1518	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1805	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
…		…
1524		1811
1525	/* 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 */
1526	ev_timer_init (&tw, 0, timeout * 1e-3);	1813	ev_timer_init (&tw, 0, timeout * 1e-3);
1527	ev_timer_start (loop, &tw);	1814	ev_timer_start (loop, &tw);
1528		1815
1529	// create on ev_io per pollfd	1816	// create one ev_io per pollfd
1530	for (int i = 0; i < nfd; ++i)	1817	for (int i = 0; i < nfd; ++i)
1531	{	1818	{
1532	ev_io_init (iow + i, io_cb, fds [i].fd,	1819	ev_io_init (iow + i, io_cb, fds [i].fd,
1533	((fds [i].events & POLLIN ? EV_READ : 0)	1820	((fds [i].events & POLLIN ? EV_READ : 0)
1534	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1821	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1535		1822
1536	fds [i].revents = 0;	1823	fds [i].revents = 0;
1537	iow [i].data = fds + i;
1538	ev_io_start (loop, iow + i);	1824	ev_io_start (loop, iow + i);
1539	}	1825	}
1540	}	1826	}
1541		1827
1542	// stop all watchers after blocking	1828	// stop all watchers after blocking
…		…
1544	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1830	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1545	{	1831	{
1546	ev_timer_stop (loop, &tw);	1832	ev_timer_stop (loop, &tw);
1547		1833
1548	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
1549	ev_io_stop (loop, iow + i);	1844	ev_io_stop (loop, iow + i);
		1845	}
1550		1846
1551	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;
1552	}	1907	}
1553		1908
1554		1909
1555	=head2 C<ev_embed> - when one backend isn't enough...	1910	=head2 C<ev_embed> - when one backend isn't enough...
1556		1911
…		…
1599	portable one.	1954	portable one.
1600		1955
1601	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
1602	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
1603	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
1604	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).
1605		1994
1606	struct ev_loop *loop_hi = ev_default_init (0);	1995	struct ev_loop *loop_hi = ev_default_init (0);
1607	struct ev_loop *loop_lo = 0;	1996	struct ev_loop *loop_lo = 0;
1608	struct ev_embed embed;	1997	struct ev_embed embed;
1609		1998
…		…
1620	ev_embed_start (loop_hi, &embed);	2009	ev_embed_start (loop_hi, &embed);
1621	}	2010	}
1622	else	2011	else
1623	loop_lo = loop_hi;	2012	loop_lo = loop_hi;
1624		2013
1625	=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).
1626		2018
1627	=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	}
1628		2029
1629	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	2030	if (!loop_socket)
		2031	loop_socket = loop;
1630		2032
1631	Configures the watcher to embed the given loop, which must be	2033	// now use loop_socket for all sockets, and loop for everything else
1632	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
1633	invoked automatically, otherwise it is the responsibility of the callback
1634	to invoke it (it will continue to be called until the sweep has been done,
1635	if you do not want thta, you need to temporarily stop the embed watcher).
1636
1637	=item ev_embed_sweep (loop, ev_embed *)
1638
1639	Make a single, non-blocking sweep over the embedded loop. This works
1640	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1641	apropriate way for embedded loops.
1642
1643	=item struct ev_loop *loop [read-only]
1644
1645	The embedded event loop.
1646
1647	=back
1648		2034
1649		2035
1650	=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
1651		2037
1652	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
…		…
1655	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,
1656	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
1657	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
1658	handlers will be invoked, too, of course.	2044	handlers will be invoked, too, of course.
1659		2045
		2046	=head3 Watcher-Specific Functions and Data Members
		2047
1660	=over 4	2048	=over 4
1661		2049
1662	=item ev_fork_init (ev_signal *, callback)	2050	=item ev_fork_init (ev_signal *, callback)
1663		2051
1664	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
1665	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,
1666	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>.
1667		2186
1668	=back	2187	=back
1669		2188
1670		2189
1671	=head1 OTHER FUNCTIONS	2190	=head1 OTHER FUNCTIONS
…		…
1844		2363
1845	myclass obj;	2364	myclass obj;
1846	ev::io iow;	2365	ev::io iow;
1847	iow.set <myclass, &myclass::io_cb> (&obj);	2366	iow.set <myclass, &myclass::io_cb> (&obj);
1848		2367
1849	=item w->set (void (*function)(watcher &w, int), void *data = 0)	2368	=item w->set<function> (void *data = 0)
1850		2369
1851	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
1852	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
1853	C<data> member and is free for you to use.	2372	C<data> member and is free for you to use.
1854		2373
		2374	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2375
1855	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> ();
1856		2382
1857	=item w->set (struct ev_loop *)	2383	=item w->set (struct ev_loop *)
1858		2384
1859	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
1860	do this when the watcher is inactive (and not pending either).	2386	do this when the watcher is inactive (and not pending either).
…		…
1873		2399
1874	=item w->stop ()	2400	=item w->stop ()
1875		2401
1876	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.
1877		2403
1878	=item w->again () C<ev::timer>, C<ev::periodic> only	2404	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1879		2405
1880	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
1881	C<ev_TYPE_again> function.	2407	C<ev_TYPE_again> function.
1882		2408
1883	=item w->sweep () C<ev::embed> only	2409	=item w->sweep () (C<ev::embed> only)
1884		2410
1885	Invokes C<ev_embed_sweep>.	2411	Invokes C<ev_embed_sweep>.
1886		2412
1887	=item w->update () C<ev::stat> only	2413	=item w->update () (C<ev::stat> only)
1888		2414
1889	Invokes C<ev_stat_stat>.	2415	Invokes C<ev_stat_stat>.
1890		2416
1891	=back	2417	=back
1892		2418
…		…
1895	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
1896	the constructor.	2422	the constructor.
1897		2423
1898	class myclass	2424	class myclass
1899	{	2425	{
1900	ev_io io; void io_cb (ev::io &w, int revents);	2426	ev::io io; void io_cb (ev::io &w, int revents);
1901	ev_idle idle void idle_cb (ev::idle &w, int revents);	2427	ev:idle idle void idle_cb (ev::idle &w, int revents);
1902		2428
1903	myclass ();	2429	myclass (int fd)
1904	}
1905
1906	myclass::myclass (int fd)
1907	{	2430	{
1908	io .set <myclass, &myclass::io_cb > (this);	2431	io .set <myclass, &myclass::io_cb > (this);
1909	idle.set <myclass, &myclass::idle_cb> (this);	2432	idle.set <myclass, &myclass::idle_cb> (this);
1910		2433
1911	io.start (fd, ev::READ);	2434	io.start (fd, ev::READ);
		2435	}
1912	}	2436	};
1913		2437
1914		2438
1915	=head1 MACRO MAGIC	2439	=head1 MACRO MAGIC
1916		2440
1917	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
1918	C<EV_MULTIPLICITY>. This option determines whether (most) functions and	2442	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1919	callbacks have an initial C<struct ev_loop *> argument.	2443	functions and callbacks have an initial C<struct ev_loop *> argument.
1920		2444
1921	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
1922	following macros are defined:	2446	following macros are defined:
1923		2447
1924	=over 4	2448	=over 4
…		…
1978	Libev can (and often is) directly embedded into host	2502	Libev can (and often is) directly embedded into host
1979	applications. Examples of applications that embed it include the Deliantra	2503	applications. Examples of applications that embed it include the Deliantra
1980	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)
1981	and rxvt-unicode.	2505	and rxvt-unicode.
1982		2506
1983	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
1984	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
1985	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
1986	libev somewhere in your source tree).	2510	libev somewhere in your source tree).
1987		2511
1988	=head2 FILESETS	2512	=head2 FILESETS
…		…
2078		2602
2079	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
2080	monotonic clock option at both compiletime and runtime. Otherwise no use	2604	monotonic clock option at both compiletime and runtime. Otherwise no use
2081	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
2082	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
2083	the functionality isn't available is safe, though, althoguh you have	2607	the functionality isn't available is safe, though, although you have
2084	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>
2085	function is hiding in (often F<-lrt>).	2609	function is hiding in (often F<-lrt>).
2086		2610
2087	=item EV_USE_REALTIME	2611	=item EV_USE_REALTIME
2088		2612
2089	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
2090	realtime clock option at compiletime (and assume its availability at	2614	realtime clock option at compiletime (and assume its availability at
2091	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
2092	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2616	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2093	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2617	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2094	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 ()>.
2095		2624
2096	=item EV_USE_SELECT	2625	=item EV_USE_SELECT
2097		2626
2098	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
2099	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
…		…
2117	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
2118	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
2119	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,
2120	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
2121	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.
2122		2659
2123	=item EV_USE_POLL	2660	=item EV_USE_POLL
2124		2661
2125	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)
2126	backend. Otherwise it will be enabled on non-win32 platforms. It	2663	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
2160		2697
2161	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
2162	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
2163	be detected at runtime.	2700	be detected at runtime.
2164		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
2165	=item EV_H	2713	=item EV_H
2166		2714
2167	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
2168	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
2169	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.
2170		2718
2171	=item EV_CONFIG_H	2719	=item EV_CONFIG_H
2172		2720
2173	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
2174	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
2175	C<EV_H>, above.	2723	C<EV_H>, above.
2176		2724
2177	=item EV_EVENT_H	2725	=item EV_EVENT_H
2178		2726
2179	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
2180	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">.
2181		2729
2182	=item EV_PROTOTYPES	2730	=item EV_PROTOTYPES
2183		2731
2184	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
2185	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
…		…
2236	=item EV_FORK_ENABLE	2784	=item EV_FORK_ENABLE
2237		2785
2238	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
2239	defined to be C<0>, then they are not.	2787	defined to be C<0>, then they are not.
2240		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
2241	=item EV_MINIMAL	2794	=item EV_MINIMAL
2242		2795
2243	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
2244	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
2245	some inlining decisions, saves roughly 30% codesize of amd64.	2798	some inlining decisions, saves roughly 30% codesize of amd64.
…		…
2251	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
2252	increase this value (I<must> be a power of two).	2805	increase this value (I<must> be a power of two).
2253		2806
2254	=item EV_INOTIFY_HASHSIZE	2807	=item EV_INOTIFY_HASHSIZE
2255		2808
2256	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
2257	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>),
2258	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>
2259	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
2260	two).	2813	two).
2261		2814
…		…
2278		2831
2279	=item ev_set_cb (ev, cb)	2832	=item ev_set_cb (ev, cb)
2280		2833
2281	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,
2282	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
2283	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
2284	their default definitions. One possible use for overriding these is to	2837	their default definitions. One possible use for overriding these is to
2285	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
2286	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	...
2287		2865
2288	=head2 EXAMPLES	2866	=head2 EXAMPLES
2289		2867
2290	For a real-world example of a program the includes libev	2868	For a real-world example of a program the includes libev
2291	verbatim, you can have a look at the EV perl module	2869	verbatim, you can have a look at the EV perl module
…		…
2332		2910
2333	=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)
2334		2912
2335	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
2336	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
2337	have to skip those 100 watchers.	2915	have to skip roughly seven (C<ld 100>) of these watchers.
2338		2916
2339	=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)
2340		2918
2341	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
2342	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.
2343		2921
2344	=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)
2345		2923
2346	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
2347	=item Stopping check/prepare/idle watchers: O(1)	2926	=item Stopping check/prepare/idle/fork/async watchers: O(1)
2348		2927
2349	=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))
2350		2929
2351	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
2352	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
2353	have many watchers waiting for the same fd or signal).	2932	have many watchers waiting for the same fd or signal).
2354		2933
2355	=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.
2356		2938
2357	=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)
2358		2940
2359	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
2360	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).
2361		2944
2362	=item Activating one watcher: O(1)	2945	=item Activating one watcher (putting it into the pending state): O(1)
2363		2946
2364	=item Priority handling: O(number_of_priorities)	2947	=item Priority handling: O(number_of_priorities)
2365		2948
2366	Priorities are implemented by allocating some space for each	2949	Priorities are implemented by allocating some space for each
2367	priority. When doing priority-based operations, libev usually has to	2950	priority. When doing priority-based operations, libev usually has to
2368	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.
2369		2963
2370	=back	2964	=back
2371		2965
2372		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
2373	=head1 AUTHOR	3034	=head1 AUTHOR
2374		3035
2375	Marc Lehmann <libev@schmorp.de>.	3036	Marc Lehmann <libev@schmorp.de>.
2376		3037

Diff Legend

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