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Revision 1.130 by root, Wed Feb 6 18:34:24 2008 UTC vs.
Revision 1.169 by root, Fri Jun 20 23:31:19 2008 UTC

…		…
2		2
3	libev - a high performance full-featured event loop written in C	3	libev - a high performance full-featured event loop written in C
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head2 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
		11	// a single header file is required
11	#include <ev.h>	12	#include <ev.h>
12		13
		14	// every watcher type has its own typedef'd struct
		15	// with the name ev_<type>
13	ev_io stdin_watcher;	16	ev_io stdin_watcher;
14	ev_timer timeout_watcher;	17	ev_timer timeout_watcher;
15		18
16	/* called when data readable on stdin */	19	// all watcher callbacks have a similar signature
		20	// this callback is called when data is readable on stdin
17	static void	21	static void
18	stdin_cb (EV_P_ struct ev_io *w, int revents)	22	stdin_cb (EV_P_ struct ev_io *w, int revents)
19	{	23	{
20	/* puts ("stdin ready"); */	24	puts ("stdin ready");
21	ev_io_stop (EV_A_ w); /* just a syntax example */	25	// for one-shot events, one must manually stop the watcher
22	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */	26	// with its corresponding stop function.
		27	ev_io_stop (EV_A_ w);
		28
		29	// this causes all nested ev_loop's to stop iterating
		30	ev_unloop (EV_A_ EVUNLOOP_ALL);
23	}	31	}
24		32
		33	// another callback, this time for a time-out
25	static void	34	static void
26	timeout_cb (EV_P_ struct ev_timer *w, int revents)	35	timeout_cb (EV_P_ struct ev_timer *w, int revents)
27	{	36	{
28	/* puts ("timeout"); */	37	puts ("timeout");
29	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */	38	// this causes the innermost ev_loop to stop iterating
		39	ev_unloop (EV_A_ EVUNLOOP_ONE);
30	}	40	}
31		41
32	int	42	int
33	main (void)	43	main (void)
34	{	44	{
		45	// use the default event loop unless you have special needs
35	struct ev_loop *loop = ev_default_loop (0);	46	struct ev_loop *loop = ev_default_loop (0);
36		47
37	/* initialise an io watcher, then start it */	48	// initialise an io watcher, then start it
		49	// this one will watch for stdin to become readable
38	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
39	ev_io_start (loop, &stdin_watcher);	51	ev_io_start (loop, &stdin_watcher);
40		52
		53	// initialise a timer watcher, then start it
41	/* simple non-repeating 5.5 second timeout */	54	// simple non-repeating 5.5 second timeout
42	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
43	ev_timer_start (loop, &timeout_watcher);	56	ev_timer_start (loop, &timeout_watcher);
44		57
45	/* loop till timeout or data ready */	58	// now wait for events to arrive
46	ev_loop (loop, 0);	59	ev_loop (loop, 0);
47		60
		61	// unloop was called, so exit
48	return 0;	62	return 0;
49	}	63	}
50		64
51	=head1 DESCRIPTION	65	=head1 DESCRIPTION
52		66
53	The newest version of this document is also available as a html-formatted	67	The newest version of this document is also available as an html-formatted
54	web page you might find easier to navigate when reading it for the first	68	web page you might find easier to navigate when reading it for the first
55	time: L<http://cvs.schmorp.de/libev/ev.html>.	69	time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>.
56		70
57	Libev is an event loop: you register interest in certain events (such as a	71	Libev is an event loop: you register interest in certain events (such as a
58	file descriptor being readable or a timeout occurring), and it will manage	72	file descriptor being readable or a timeout occurring), and it will manage
59	these event sources and provide your program with events.	73	these event sources and provide your program with events.
60		74
…		…
84	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent	98	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
85	for example).	99	for example).
86		100
87	=head2 CONVENTIONS	101	=head2 CONVENTIONS
88		102
89	Libev is very configurable. In this manual the default configuration will	103	Libev is very configurable. In this manual the default (and most common)
90	be described, which supports multiple event loops. For more info about	104	configuration will be described, which supports multiple event loops. For
91	various configuration options please have a look at B<EMBED> section in	105	more info about various configuration options please have a look at
92	this manual. If libev was configured without support for multiple event	106	B<EMBED> section in this manual. If libev was configured without support
93	loops, then all functions taking an initial argument of name C<loop>	107	for multiple event loops, then all functions taking an initial argument of
94	(which is always of type C<struct ev_loop *>) will not have this argument.	108	name C<loop> (which is always of type C<struct ev_loop *>) will not have
		109	this argument.
95		110
96	=head2 TIME REPRESENTATION	111	=head2 TIME REPRESENTATION
97		112
98	Libev represents time as a single floating point number, representing the	113	Libev represents time as a single floating point number, representing the
99	(fractional) number of seconds since the (POSIX) epoch (somewhere near	114	(fractional) number of seconds since the (POSIX) epoch (somewhere near
100	the beginning of 1970, details are complicated, don't ask). This type is	115	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	116	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	117	to the C<double> type in C, and when you need to do any calculations on
103	it, you should treat it as some floatingpoint value. Unlike the name	118	it, you should treat it as some floating point value. Unlike the name
104	component C<stamp> might indicate, it is also used for time differences	119	component C<stamp> might indicate, it is also used for time differences
105	throughout libev.	120	throughout libev.
		121
		122	=head1 ERROR HANDLING
		123
		124	Libev knows three classes of errors: operating system errors, usage errors
		125	and internal errors (bugs).
		126
		127	When libev catches an operating system error it cannot handle (for example
		128	a system call indicating a condition libev cannot fix), it calls the callback
		129	set via C<ev_set_syserr_cb>, which is supposed to fix the problem or
		130	abort. The default is to print a diagnostic message and to call C<abort
		131	()>.
		132
		133	When libev detects a usage error such as a negative timer interval, then
		134	it will print a diagnostic message and abort (via the C<assert> mechanism,
		135	so C<NDEBUG> will disable this checking): these are programming errors in
		136	the libev caller and need to be fixed there.
		137
		138	Libev also has a few internal error-checking C<assert>ions, and also has
		139	extensive consistency checking code. These do not trigger under normal
		140	circumstances, as they indicate either a bug in libev or worse.
		141
106		142
107	=head1 GLOBAL FUNCTIONS	143	=head1 GLOBAL FUNCTIONS
108		144
109	These functions can be called anytime, even before initialising the	145	These functions can be called anytime, even before initialising the
110	library in any way.	146	library in any way.
…		…
119		155
120	=item ev_sleep (ev_tstamp interval)	156	=item ev_sleep (ev_tstamp interval)
121		157
122	Sleep for the given interval: The current thread will be blocked until	158	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	159	either it is interrupted or the given time interval has passed. Basically
124	this is a subsecond-resolution C<sleep ()>.	160	this is a sub-second-resolution C<sleep ()>.
125		161
126	=item int ev_version_major ()	162	=item int ev_version_major ()
127		163
128	=item int ev_version_minor ()	164	=item int ev_version_minor ()
129		165
…		…
142	not a problem.	178	not a problem.
143		179
144	Example: Make sure we haven't accidentally been linked against the wrong	180	Example: Make sure we haven't accidentally been linked against the wrong
145	version.	181	version.
146		182
147	assert (("libev version mismatch",	183	assert (("libev version mismatch",
148	ev_version_major () == EV_VERSION_MAJOR	184	ev_version_major () == EV_VERSION_MAJOR
149	&& ev_version_minor () >= EV_VERSION_MINOR));	185	&& ev_version_minor () >= EV_VERSION_MINOR));
150		186
151	=item unsigned int ev_supported_backends ()	187	=item unsigned int ev_supported_backends ()
152		188
153	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>	189	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>
154	value) compiled into this binary of libev (independent of their	190	value) compiled into this binary of libev (independent of their
…		…
156	a description of the set values.	192	a description of the set values.
157		193
158	Example: make sure we have the epoll method, because yeah this is cool and	194	Example: make sure we have the epoll method, because yeah this is cool and
159	a must have and can we have a torrent of it please!!!11	195	a must have and can we have a torrent of it please!!!11
160		196
161	assert (("sorry, no epoll, no sex",	197	assert (("sorry, no epoll, no sex",
162	ev_supported_backends () & EVBACKEND_EPOLL));	198	ev_supported_backends () & EVBACKEND_EPOLL));
163		199
164	=item unsigned int ev_recommended_backends ()	200	=item unsigned int ev_recommended_backends ()
165		201
166	Return the set of all backends compiled into this binary of libev and also	202	Return the set of all backends compiled into this binary of libev and also
167	recommended for this platform. This set is often smaller than the one	203	recommended for this platform. This set is often smaller than the one
168	returned by C<ev_supported_backends>, as for example kqueue is broken on	204	returned by C<ev_supported_backends>, as for example kqueue is broken on
169	most BSDs and will not be autodetected unless you explicitly request it	205	most BSDs and will not be auto-detected unless you explicitly request it
170	(assuming you know what you are doing). This is the set of backends that	206	(assuming you know what you are doing). This is the set of backends that
171	libev will probe for if you specify no backends explicitly.	207	libev will probe for if you specify no backends explicitly.
172		208
173	=item unsigned int ev_embeddable_backends ()	209	=item unsigned int ev_embeddable_backends ()
174		210
…		…
181	See the description of C<ev_embed> watchers for more info.	217	See the description of C<ev_embed> watchers for more info.
182		218
183	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	219	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
184		220
185	Sets the allocation function to use (the prototype is similar - the	221	Sets the allocation function to use (the prototype is similar - the
186	semantics is identical - to the realloc C function). It is used to	222	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
187	allocate and free memory (no surprises here). If it returns zero when	223	used to allocate and free memory (no surprises here). If it returns zero
188	memory needs to be allocated, the library might abort or take some	224	when memory needs to be allocated (C<size != 0>), the library might abort
189	potentially destructive action. The default is your system realloc	225	or take some potentially destructive action.
190	function.	226
		227	Since some systems (at least OpenBSD and Darwin) fail to implement
		228	correct C<realloc> semantics, libev will use a wrapper around the system
		229	C<realloc> and C<free> functions by default.
191		230
192	You could override this function in high-availability programs to, say,	231	You could override this function in high-availability programs to, say,
193	free some memory if it cannot allocate memory, to use a special allocator,	232	free some memory if it cannot allocate memory, to use a special allocator,
194	or even to sleep a while and retry until some memory is available.	233	or even to sleep a while and retry until some memory is available.
195		234
196	Example: Replace the libev allocator with one that waits a bit and then	235	Example: Replace the libev allocator with one that waits a bit and then
197	retries).	236	retries (example requires a standards-compliant C<realloc>).
198		237
199	static void *	238	static void *
200	persistent_realloc (void *ptr, size_t size)	239	persistent_realloc (void *ptr, size_t size)
201	{	240	{
202	for (;;)	241	for (;;)
…		…
213	...	252	...
214	ev_set_allocator (persistent_realloc);	253	ev_set_allocator (persistent_realloc);
215		254
216	=item ev_set_syserr_cb (void (*cb)(const char *msg));	255	=item ev_set_syserr_cb (void (*cb)(const char *msg));
217		256
218	Set the callback function to call on a retryable syscall error (such	257	Set the callback function to call on a retryable system call error (such
219	as failed select, poll, epoll_wait). The message is a printable string	258	as failed select, poll, epoll_wait). The message is a printable string
220	indicating the system call or subsystem causing the problem. If this	259	indicating the system call or subsystem causing the problem. If this
221	callback is set, then libev will expect it to remedy the sitution, no	260	callback is set, then libev will expect it to remedy the situation, no
222	matter what, when it returns. That is, libev will generally retry the	261	matter what, when it returns. That is, libev will generally retry the
223	requested operation, or, if the condition doesn't go away, do bad stuff	262	requested operation, or, if the condition doesn't go away, do bad stuff
224	(such as abort).	263	(such as abort).
225		264
226	Example: This is basically the same thing that libev does internally, too.	265	Example: This is basically the same thing that libev does internally, too.
…		…
240	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	279	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
241		280
242	An event loop is described by a C<struct ev_loop *>. The library knows two	281	An event loop is described by a C<struct ev_loop *>. The library knows two
243	types of such loops, the I<default> loop, which supports signals and child	282	types of such loops, the I<default> loop, which supports signals and child
244	events, and dynamically created loops which do not.	283	events, and dynamically created loops which do not.
245
246	If you use threads, a common model is to run the default event loop
247	in your main thread (or in a separate thread) and for each thread you
248	create, you also create another event loop. Libev itself does no locking
249	whatsoever, so if you mix calls to the same event loop in different
250	threads, make sure you lock (this is usually a bad idea, though, even if
251	done correctly, because it's hideous and inefficient).
252		284
253	=over 4	285	=over 4
254		286
255	=item struct ev_loop *ev_default_loop (unsigned int flags)	287	=item struct ev_loop *ev_default_loop (unsigned int flags)
256		288
…		…
260	flags. If that is troubling you, check C<ev_backend ()> afterwards).	292	flags. If that is troubling you, check C<ev_backend ()> afterwards).
261		293
262	If you don't know what event loop to use, use the one returned from this	294	If you don't know what event loop to use, use the one returned from this
263	function.	295	function.
264		296
		297	Note that this function is I<not> thread-safe, so if you want to use it
		298	from multiple threads, you have to lock (note also that this is unlikely,
		299	as loops cannot bes hared easily between threads anyway).
		300
265	The default loop is the only loop that can handle C<ev_signal> and	301	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	302	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	303	for C<SIGCHLD>. If this is a problem for your application you can either
268	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	304	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	305	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
270	C<ev_default_init>.	306	C<ev_default_init>.
271		307
272	The flags argument can be used to specify special behaviour or specific	308	The flags argument can be used to specify special behaviour or specific
…		…
281	The default flags value. Use this if you have no clue (it's the right	317	The default flags value. Use this if you have no clue (it's the right
282	thing, believe me).	318	thing, believe me).
283		319
284	=item C<EVFLAG_NOENV>	320	=item C<EVFLAG_NOENV>
285		321
286	If this flag bit is ored into the flag value (or the program runs setuid	322	If this flag bit is or'ed into the flag value (or the program runs setuid
287	or setgid) then libev will I<not> look at the environment variable	323	or setgid) then libev will I<not> look at the environment variable
288	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	324	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
289	override the flags completely if it is found in the environment. This is	325	override the flags completely if it is found in the environment. This is
290	useful to try out specific backends to test their performance, or to work	326	useful to try out specific backends to test their performance, or to work
291	around bugs.	327	around bugs.
…		…
297	enabling this flag.	333	enabling this flag.
298		334
299	This works by calling C<getpid ()> on every iteration of the loop,	335	This works by calling C<getpid ()> on every iteration of the loop,
300	and thus this might slow down your event loop if you do a lot of loop	336	and thus this might slow down your event loop if you do a lot of loop
301	iterations and little real work, but is usually not noticeable (on my	337	iterations and little real work, but is usually not noticeable (on my
302	Linux system for example, C<getpid> is actually a simple 5-insn sequence	338	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
303	without a syscall and thus I<very> fast, but my Linux system also has	339	without a system call and thus I<very> fast, but my GNU/Linux system also has
304	C<pthread_atfork> which is even faster).	340	C<pthread_atfork> which is even faster).
305		341
306	The big advantage of this flag is that you can forget about fork (and	342	The big advantage of this flag is that you can forget about fork (and
307	forget about forgetting to tell libev about forking) when you use this	343	forget about forgetting to tell libev about forking) when you use this
308	flag.	344	flag.
309		345
310	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>	346	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
311	environment variable.	347	environment variable.
312		348
313	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	349	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
314		350
315	This is your standard select(2) backend. Not I<completely> standard, as	351	This is your standard select(2) backend. Not I<completely> standard, as
…		…
317	but if that fails, expect a fairly low limit on the number of fds when	353	but if that fails, expect a fairly low limit on the number of fds when
318	using this backend. It doesn't scale too well (O(highest_fd)), but its	354	using this backend. It doesn't scale too well (O(highest_fd)), but its
319	usually the fastest backend for a low number of (low-numbered :) fds.	355	usually the fastest backend for a low number of (low-numbered :) fds.
320		356
321	To get good performance out of this backend you need a high amount of	357	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	358	parallelism (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	359	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	360	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	361	a look at C<ev_set_io_collect_interval ()> to increase the amount of
326	readyness notifications you get per iteration.	362	readiness notifications you get per iteration.
327		363
328	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	364	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
329		365
330	And this is your standard poll(2) backend. It's more complicated	366	And this is your standard poll(2) backend. It's more complicated
331	than select, but handles sparse fds better and has no artificial	367	than select, but handles sparse fds better and has no artificial
…		…
339	For few fds, this backend is a bit little slower than poll and select,	375	For few fds, this backend is a bit little slower than poll and select,
340	but it scales phenomenally better. While poll and select usually scale	376	but it scales phenomenally better. While poll and select usually scale
341	like O(total_fds) where n is the total number of fds (or the highest fd),	377	like O(total_fds) where n is the total number of fds (or the highest fd),
342	epoll scales either O(1) or O(active_fds). The epoll design has a number	378	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	379	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	380	cases and requiring a system call per fd change, no fork support and bad
345	support for dup.	381	support for dup.
346		382
347	While stopping, setting and starting an I/O watcher in the same iteration	383	While stopping, setting and starting an I/O watcher in the same iteration
348	will result in some caching, there is still a syscall per such incident	384	will result in some caching, there is still a system call per such incident
349	(because the fd could point to a different file description now), so its	385	(because the fd could point to a different file description now), so its
350	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	386	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
351	very well if you register events for both fds.	387	very well if you register events for both fds.
352		388
353	Please note that epoll sometimes generates spurious notifications, so you	389	Please note that epoll sometimes generates spurious notifications, so you
…		…
356		392
357	Best performance from this backend is achieved by not unregistering all	393	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.	394	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.	395	keep at least one watcher active per fd at all times.
360		396
361	While nominally embeddeble in other event loops, this feature is broken in	397	While nominally embeddable in other event loops, this feature is broken in
362	all kernel versions tested so far.	398	all kernel versions tested so far.
363		399
364	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	400	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
365		401
366	Kqueue deserves special mention, as at the time of this writing, it	402	Kqueue deserves special mention, as at the time of this writing, it
367	was broken on all BSDs except NetBSD (usually it doesn't work reliably	403	was broken on all BSDs except NetBSD (usually it doesn't work reliably
368	with anything but sockets and pipes, except on Darwin, where of course	404	with anything but sockets and pipes, except on Darwin, where of course
369	it's completely useless). For this reason it's not being "autodetected"	405	it's completely useless). For this reason it's not being "auto-detected"
370	unless you explicitly specify it explicitly in the flags (i.e. using	406	unless you explicitly specify it explicitly in the flags (i.e. using
371	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)	407	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
372	system like NetBSD.	408	system like NetBSD.
373		409
374	You still can embed kqueue into a normal poll or select backend and use it	410	You still can embed kqueue into a normal poll or select backend and use it
…		…
376	the target platform). See C<ev_embed> watchers for more info.	412	the target platform). See C<ev_embed> watchers for more info.
377		413
378	It scales in the same way as the epoll backend, but the interface to the	414	It scales in the same way as the epoll backend, but the interface to the
379	kernel is more efficient (which says nothing about its actual speed, of	415	kernel is more efficient (which says nothing about its actual speed, of
380	course). While stopping, setting and starting an I/O watcher does never	416	course). While stopping, setting and starting an I/O watcher does never
381	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to	417	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
382	two event changes per incident, support for C<fork ()> is very bad and it	418	two event changes per incident, support for C<fork ()> is very bad and it
383	drops fds silently in similarly hard-to-detect cases.	419	drops fds silently in similarly hard-to-detect cases.
384		420
385	This backend usually performs well under most conditions.	421	This backend usually performs well under most conditions.
386		422
…		…
401	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	437	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
402		438
403	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	439	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
404	it's really slow, but it still scales very well (O(active_fds)).	440	it's really slow, but it still scales very well (O(active_fds)).
405		441
406	Please note that solaris event ports can deliver a lot of spurious	442	Please note that Solaris event ports can deliver a lot of spurious
407	notifications, so you need to use non-blocking I/O or other means to avoid	443	notifications, so you need to use non-blocking I/O or other means to avoid
408	blocking when no data (or space) is available.	444	blocking when no data (or space) is available.
409		445
410	While this backend scales well, it requires one system call per active	446	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	447	file descriptor per loop iteration. For small and medium numbers of file
412	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	448	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
413	might perform better.	449	might perform better.
414		450
415	On the positive side, ignoring the spurious readyness notifications, this	451	On the positive side, ignoring the spurious readiness notifications, this
416	backend actually performed to specification in all tests and is fully	452	backend actually performed to specification in all tests and is fully
417	embeddable, which is a rare feat among the OS-specific backends.	453	embeddable, which is a rare feat among the OS-specific backends.
418		454
419	=item C<EVBACKEND_ALL>	455	=item C<EVBACKEND_ALL>
420		456
…		…
424		460
425	It is definitely not recommended to use this flag.	461	It is definitely not recommended to use this flag.
426		462
427	=back	463	=back
428		464
429	If one or more of these are ored into the flags value, then only these	465	If one or more of these are or'ed into the flags value, then only these
430	backends will be tried (in the reverse order as listed here). If none are	466	backends will be tried (in the reverse order as listed here). If none are
431	specified, all backends in C<ev_recommended_backends ()> will be tried.	467	specified, all backends in C<ev_recommended_backends ()> will be tried.
432		468
433	The most typical usage is like this:	469	The most typical usage is like this:
434		470
435	if (!ev_default_loop (0))	471	if (!ev_default_loop (0))
436	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	472	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
437		473
438	Restrict libev to the select and poll backends, and do not allow	474	Restrict libev to the select and poll backends, and do not allow
439	environment settings to be taken into account:	475	environment settings to be taken into account:
440		476
441	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	477	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
442		478
443	Use whatever libev has to offer, but make sure that kqueue is used if	479	Use whatever libev has to offer, but make sure that kqueue is used if
444	available (warning, breaks stuff, best use only with your own private	480	available (warning, breaks stuff, best use only with your own private
445	event loop and only if you know the OS supports your types of fds):	481	event loop and only if you know the OS supports your types of fds):
446		482
447	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	483	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
448		484
449	=item struct ev_loop *ev_loop_new (unsigned int flags)	485	=item struct ev_loop *ev_loop_new (unsigned int flags)
450		486
451	Similar to C<ev_default_loop>, but always creates a new event loop that is	487	Similar to C<ev_default_loop>, but always creates a new event loop that is
452	always distinct from the default loop. Unlike the default loop, it cannot	488	always distinct from the default loop. Unlike the default loop, it cannot
453	handle signal and child watchers, and attempts to do so will be greeted by	489	handle signal and child watchers, and attempts to do so will be greeted by
454	undefined behaviour (or a failed assertion if assertions are enabled).	490	undefined behaviour (or a failed assertion if assertions are enabled).
455		491
		492	Note that this function I<is> thread-safe, and the recommended way to use
		493	libev with threads is indeed to create one loop per thread, and using the
		494	default loop in the "main" or "initial" thread.
		495
456	Example: Try to create a event loop that uses epoll and nothing else.	496	Example: Try to create a event loop that uses epoll and nothing else.
457		497
458	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	498	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
459	if (!epoller)	499	if (!epoller)
460	fatal ("no epoll found here, maybe it hides under your chair");	500	fatal ("no epoll found here, maybe it hides under your chair");
461		501
462	=item ev_default_destroy ()	502	=item ev_default_destroy ()
463		503
464	Destroys the default loop again (frees all memory and kernel state	504	Destroys the default loop again (frees all memory and kernel state
465	etc.). None of the active event watchers will be stopped in the normal	505	etc.). None of the active event watchers will be stopped in the normal
466	sense, so e.g. C<ev_is_active> might still return true. It is your	506	sense, so e.g. C<ev_is_active> might still return true. It is your
467	responsibility to either stop all watchers cleanly yoursef I<before>	507	responsibility to either stop all watchers cleanly yourself I<before>
468	calling this function, or cope with the fact afterwards (which is usually	508	calling this function, or cope with the fact afterwards (which is usually
469	the easiest thing, you can just ignore the watchers and/or C<free ()> them	509	the easiest thing, you can just ignore the watchers and/or C<free ()> them
470	for example).	510	for example).
471		511
472	Note that certain global state, such as signal state, will not be freed by	512	Note that certain global state, such as signal state, will not be freed by
…		…
506		546
507	Like C<ev_default_fork>, but acts on an event loop created by	547	Like C<ev_default_fork>, but acts on an event loop created by
508	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	548	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
509	after fork, and how you do this is entirely your own problem.	549	after fork, and how you do this is entirely your own problem.
510		550
		551	=item int ev_is_default_loop (loop)
		552
		553	Returns true when the given loop actually is the default loop, false otherwise.
		554
511	=item unsigned int ev_loop_count (loop)	555	=item unsigned int ev_loop_count (loop)
512		556
513	Returns the count of loop iterations for the loop, which is identical to	557	Returns the count of loop iterations for the loop, which is identical to
514	the number of times libev did poll for new events. It starts at C<0> and	558	the number of times libev did poll for new events. It starts at C<0> and
515	happily wraps around with enough iterations.	559	happily wraps around with enough iterations.
…		…
549	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	593	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
550	those events and any outstanding ones, but will not block your process in	594	those events and any outstanding ones, but will not block your process in
551	case there are no events and will return after one iteration of the loop.	595	case there are no events and will return after one iteration of the loop.
552		596
553	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	597	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
554	neccessary) and will handle those and any outstanding ones. It will block	598	necessary) and will handle those and any outstanding ones. It will block
555	your process until at least one new event arrives, and will return after	599	your process until at least one new event arrives, and will return after
556	one iteration of the loop. This is useful if you are waiting for some	600	one iteration of the loop. This is useful if you are waiting for some
557	external event in conjunction with something not expressible using other	601	external event in conjunction with something not expressible using other
558	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	602	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
559	usually a better approach for this kind of thing.	603	usually a better approach for this kind of thing.
…		…
620	respectively).	664	respectively).
621		665
622	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	666	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
623	running when nothing else is active.	667	running when nothing else is active.
624		668
625	struct ev_signal exitsig;	669	struct ev_signal exitsig;
626	ev_signal_init (&exitsig, sig_cb, SIGINT);	670	ev_signal_init (&exitsig, sig_cb, SIGINT);
627	ev_signal_start (loop, &exitsig);	671	ev_signal_start (loop, &exitsig);
628	evf_unref (loop);	672	evf_unref (loop);
629		673
630	Example: For some weird reason, unregister the above signal handler again.	674	Example: For some weird reason, unregister the above signal handler again.
631		675
632	ev_ref (loop);	676	ev_ref (loop);
633	ev_signal_stop (loop, &exitsig);	677	ev_signal_stop (loop, &exitsig);
634		678
635	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	679	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
636		680
637	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	681	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
638		682
…		…
660	to spend more time collecting timeouts, at the expense of increased	704	to spend more time collecting timeouts, at the expense of increased
661	latency (the watcher callback will be called later). C<ev_io> watchers	705	latency (the watcher callback will be called later). C<ev_io> watchers
662	will not be affected. Setting this to a non-null value will not introduce	706	will not be affected. Setting this to a non-null value will not introduce
663	any overhead in libev.	707	any overhead in libev.
664		708
665	Many (busy) programs can usually benefit by setting the io collect	709	Many (busy) programs can usually benefit by setting the I/O collect
666	interval to a value near C<0.1> or so, which is often enough for	710	interval to a value near C<0.1> or so, which is often enough for
667	interactive servers (of course not for games), likewise for timeouts. It	711	interactive servers (of course not for games), likewise for timeouts. It
668	usually doesn't make much sense to set it to a lower value than C<0.01>,	712	usually doesn't make much sense to set it to a lower value than C<0.01>,
669	as this approsaches the timing granularity of most systems.	713	as this approaches the timing granularity of most systems.
		714
		715	=item ev_loop_verify (loop)
		716
		717	This function only does something when C<EV_VERIFY> support has been
		718	compiled in. It tries to go through all internal structures and checks
		719	them for validity. If anything is found to be inconsistent, it will print
		720	an error message to standard error and call C<abort ()>.
		721
		722	This can be used to catch bugs inside libev itself: under normal
		723	circumstances, this function will never abort as of course libev keeps its
		724	data structures consistent.
670		725
671	=back	726	=back
672		727
673		728
674	=head1 ANATOMY OF A WATCHER	729	=head1 ANATOMY OF A WATCHER
675		730
676	A watcher is a structure that you create and register to record your	731	A watcher is a structure that you create and register to record your
677	interest in some event. For instance, if you want to wait for STDIN to	732	interest in some event. For instance, if you want to wait for STDIN to
678	become readable, you would create an C<ev_io> watcher for that:	733	become readable, you would create an C<ev_io> watcher for that:
679		734
680	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	735	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
681	{	736	{
682	ev_io_stop (w);	737	ev_io_stop (w);
683	ev_unloop (loop, EVUNLOOP_ALL);	738	ev_unloop (loop, EVUNLOOP_ALL);
684	}	739	}
685		740
686	struct ev_loop *loop = ev_default_loop (0);	741	struct ev_loop *loop = ev_default_loop (0);
687	struct ev_io stdin_watcher;	742	struct ev_io stdin_watcher;
688	ev_init (&stdin_watcher, my_cb);	743	ev_init (&stdin_watcher, my_cb);
689	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	744	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
690	ev_io_start (loop, &stdin_watcher);	745	ev_io_start (loop, &stdin_watcher);
691	ev_loop (loop, 0);	746	ev_loop (loop, 0);
692		747
693	As you can see, you are responsible for allocating the memory for your	748	As you can see, you are responsible for allocating the memory for your
694	watcher structures (and it is usually a bad idea to do this on the stack,	749	watcher structures (and it is usually a bad idea to do this on the stack,
695	although this can sometimes be quite valid).	750	although this can sometimes be quite valid).
696		751
697	Each watcher structure must be initialised by a call to C<ev_init	752	Each watcher structure must be initialised by a call to C<ev_init
698	(watcher *, callback)>, which expects a callback to be provided. This	753	(watcher *, callback)>, which expects a callback to be provided. This
699	callback gets invoked each time the event occurs (or, in the case of io	754	callback gets invoked each time the event occurs (or, in the case of I/O
700	watchers, each time the event loop detects that the file descriptor given	755	watchers, each time the event loop detects that the file descriptor given
701	is readable and/or writable).	756	is readable and/or writable).
702		757
703	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	758	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
704	with arguments specific to this watcher type. There is also a macro	759	with arguments specific to this watcher type. There is also a macro
…		…
780		835
781	The given async watcher has been asynchronously notified (see C<ev_async>).	836	The given async watcher has been asynchronously notified (see C<ev_async>).
782		837
783	=item C<EV_ERROR>	838	=item C<EV_ERROR>
784		839
785	An unspecified error has occured, the watcher has been stopped. This might	840	An unspecified error has occurred, the watcher has been stopped. This might
786	happen because the watcher could not be properly started because libev	841	happen because the watcher could not be properly started because libev
787	ran out of memory, a file descriptor was found to be closed or any other	842	ran out of memory, a file descriptor was found to be closed or any other
788	problem. You best act on it by reporting the problem and somehow coping	843	problem. You best act on it by reporting the problem and somehow coping
789	with the watcher being stopped.	844	with the watcher being stopped.
790		845
791	Libev will usually signal a few "dummy" events together with an error,	846	Libev will usually signal a few "dummy" events together with an error,
792	for example it might indicate that a fd is readable or writable, and if	847	for example it might indicate that a fd is readable or writable, and if
793	your callbacks is well-written it can just attempt the operation and cope	848	your callbacks is well-written it can just attempt the operation and cope
794	with the error from read() or write(). This will not work in multithreaded	849	with the error from read() or write(). This will not work in multi-threaded
795	programs, though, so beware.	850	programs, though, so beware.
796		851
797	=back	852	=back
798		853
799	=head2 GENERIC WATCHER FUNCTIONS	854	=head2 GENERIC WATCHER FUNCTIONS
…		…
829	Although some watcher types do not have type-specific arguments	884	Although some watcher types do not have type-specific arguments
830	(e.g. C<ev_prepare>) you still need to call its C<set> macro.	885	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
831		886
832	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	887	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
833		888
834	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	889	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
835	calls into a single call. This is the most convinient method to initialise	890	calls into a single call. This is the most convenient method to initialise
836	a watcher. The same limitations apply, of course.	891	a watcher. The same limitations apply, of course.
837		892
838	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	893	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
839		894
840	Starts (activates) the given watcher. Only active watchers will receive	895	Starts (activates) the given watcher. Only active watchers will receive
…		…
923	to associate arbitrary data with your watcher. If you need more data and	978	to associate arbitrary data with your watcher. If you need more data and
924	don't want to allocate memory and store a pointer to it in that data	979	don't want to allocate memory and store a pointer to it in that data
925	member, you can also "subclass" the watcher type and provide your own	980	member, you can also "subclass" the watcher type and provide your own
926	data:	981	data:
927		982
928	struct my_io	983	struct my_io
929	{	984	{
930	struct ev_io io;	985	struct ev_io io;
931	int otherfd;	986	int otherfd;
932	void *somedata;	987	void *somedata;
933	struct whatever *mostinteresting;	988	struct whatever *mostinteresting;
934	}	989	}
935		990
936	And since your callback will be called with a pointer to the watcher, you	991	And since your callback will be called with a pointer to the watcher, you
937	can cast it back to your own type:	992	can cast it back to your own type:
938		993
939	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	994	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
940	{	995	{
941	struct my_io *w = (struct my_io *)w_;	996	struct my_io *w = (struct my_io *)w_;
942	...	997	...
943	}	998	}
944		999
945	More interesting and less C-conformant ways of casting your callback type	1000	More interesting and less C-conformant ways of casting your callback type
946	instead have been omitted.	1001	instead have been omitted.
947		1002
948	Another common scenario is having some data structure with multiple	1003	Another common scenario is having some data structure with multiple
949	watchers:	1004	watchers:
950		1005
951	struct my_biggy	1006	struct my_biggy
952	{	1007	{
953	int some_data;	1008	int some_data;
954	ev_timer t1;	1009	ev_timer t1;
955	ev_timer t2;	1010	ev_timer t2;
956	}	1011	}
957		1012
958	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1013	In this case getting the pointer to C<my_biggy> is a bit more complicated,
959	you need to use C<offsetof>:	1014	you need to use C<offsetof>:
960		1015
961	#include <stddef.h>	1016	#include <stddef.h>
962		1017
963	static void	1018	static void
964	t1_cb (EV_P_ struct ev_timer *w, int revents)	1019	t1_cb (EV_P_ struct ev_timer *w, int revents)
965	{	1020	{
966	struct my_biggy big = (struct my_biggy *	1021	struct my_biggy big = (struct my_biggy *
967	(((char *)w) - offsetof (struct my_biggy, t1));	1022	(((char *)w) - offsetof (struct my_biggy, t1));
968	}	1023	}
969		1024
970	static void	1025	static void
971	t2_cb (EV_P_ struct ev_timer *w, int revents)	1026	t2_cb (EV_P_ struct ev_timer *w, int revents)
972	{	1027	{
973	struct my_biggy big = (struct my_biggy *	1028	struct my_biggy big = (struct my_biggy *
974	(((char *)w) - offsetof (struct my_biggy, t2));	1029	(((char *)w) - offsetof (struct my_biggy, t2));
975	}	1030	}
976		1031
977		1032
978	=head1 WATCHER TYPES	1033	=head1 WATCHER TYPES
979		1034
980	This section describes each watcher in detail, but will not repeat	1035	This section describes each watcher in detail, but will not repeat
…		…
1009	If you must do this, then force the use of a known-to-be-good backend	1064	If you must do this, then force the use of a known-to-be-good backend
1010	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1065	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1011	C<EVBACKEND_POLL>).	1066	C<EVBACKEND_POLL>).
1012		1067
1013	Another thing you have to watch out for is that it is quite easy to	1068	Another thing you have to watch out for is that it is quite easy to
1014	receive "spurious" readyness notifications, that is your callback might	1069	receive "spurious" readiness notifications, that is your callback might
1015	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1070	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1016	because there is no data. Not only are some backends known to create a	1071	because there is no data. Not only are some backends known to create a
1017	lot of those (for example solaris ports), it is very easy to get into	1072	lot of those (for example Solaris ports), it is very easy to get into
1018	this situation even with a relatively standard program structure. Thus	1073	this situation even with a relatively standard program structure. Thus
1019	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1074	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1020	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1075	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1021		1076
1022	If you cannot run the fd in non-blocking mode (for example you should not	1077	If you cannot run the fd in non-blocking mode (for example you should not
1023	play around with an Xlib connection), then you have to seperately re-test	1078	play around with an Xlib connection), then you have to separately re-test
1024	whether a file descriptor is really ready with a known-to-be good interface	1079	whether a file descriptor is really ready with a known-to-be good interface
1025	such as poll (fortunately in our Xlib example, Xlib already does this on	1080	such as poll (fortunately in our Xlib example, Xlib already does this on
1026	its own, so its quite safe to use).	1081	its own, so its quite safe to use).
1027		1082
1028	=head3 The special problem of disappearing file descriptors	1083	=head3 The special problem of disappearing file descriptors
…		…
1066	To support fork in your programs, you either have to call	1121	To support fork in your programs, you either have to call
1067	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,	1122	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
1068	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or	1123	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
1069	C<EVBACKEND_POLL>.	1124	C<EVBACKEND_POLL>.
1070		1125
		1126	=head3 The special problem of SIGPIPE
		1127
		1128	While not really specific to libev, it is easy to forget about SIGPIPE:
		1129	when reading from a pipe whose other end has been closed, your program
		1130	gets send a SIGPIPE, which, by default, aborts your program. For most
		1131	programs this is sensible behaviour, for daemons, this is usually
		1132	undesirable.
		1133
		1134	So when you encounter spurious, unexplained daemon exits, make sure you
		1135	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
		1136	somewhere, as that would have given you a big clue).
		1137
1071		1138
1072	=head3 Watcher-Specific Functions	1139	=head3 Watcher-Specific Functions
1073		1140
1074	=over 4	1141	=over 4
1075		1142
1076	=item ev_io_init (ev_io *, callback, int fd, int events)	1143	=item ev_io_init (ev_io *, callback, int fd, int events)
1077		1144
1078	=item ev_io_set (ev_io *, int fd, int events)	1145	=item ev_io_set (ev_io *, int fd, int events)
1079		1146
1080	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1147	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1081	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1148	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1082	C<EV_READ | EV_WRITE> to receive the given events.	1149	C<EV_READ | EV_WRITE> to receive the given events.
1083		1150
1084	=item int fd [read-only]	1151	=item int fd [read-only]
1085		1152
1086	The file descriptor being watched.	1153	The file descriptor being watched.
…		…
1095		1162
1096	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1163	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1097	readable, but only once. Since it is likely line-buffered, you could	1164	readable, but only once. Since it is likely line-buffered, you could
1098	attempt to read a whole line in the callback.	1165	attempt to read a whole line in the callback.
1099		1166
1100	static void	1167	static void
1101	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1168	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1102	{	1169	{
1103	ev_io_stop (loop, w);	1170	ev_io_stop (loop, w);
1104	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1171	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1105	}	1172	}
1106		1173
1107	...	1174	...
1108	struct ev_loop *loop = ev_default_init (0);	1175	struct ev_loop *loop = ev_default_init (0);
1109	struct ev_io stdin_readable;	1176	struct ev_io stdin_readable;
1110	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1177	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1111	ev_io_start (loop, &stdin_readable);	1178	ev_io_start (loop, &stdin_readable);
1112	ev_loop (loop, 0);	1179	ev_loop (loop, 0);
1113		1180
1114		1181
1115	=head2 C<ev_timer> - relative and optionally repeating timeouts	1182	=head2 C<ev_timer> - relative and optionally repeating timeouts
1116		1183
1117	Timer watchers are simple relative timers that generate an event after a	1184	Timer watchers are simple relative timers that generate an event after a
1118	given time, and optionally repeating in regular intervals after that.	1185	given time, and optionally repeating in regular intervals after that.
1119		1186
1120	The timers are based on real time, that is, if you register an event that	1187	The timers are based on real time, that is, if you register an event that
1121	times out after an hour and you reset your system clock to last years	1188	times out after an hour and you reset your system clock to January last
1122	time, it will still time out after (roughly) and hour. "Roughly" because	1189	year, it will still time out after (roughly) and hour. "Roughly" because
1123	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1190	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1124	monotonic clock option helps a lot here).	1191	monotonic clock option helps a lot here).
1125		1192
1126	The relative timeouts are calculated relative to the C<ev_now ()>	1193	The relative timeouts are calculated relative to the C<ev_now ()>
1127	time. This is usually the right thing as this timestamp refers to the time	1194	time. This is usually the right thing as this timestamp refers to the time
…		…
1129	you suspect event processing to be delayed and you I<need> to base the timeout	1196	you suspect event processing to be delayed and you I<need> to base the timeout
1130	on the current time, use something like this to adjust for this:	1197	on the current time, use something like this to adjust for this:
1131		1198
1132	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1199	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1133		1200
1134	The callback is guarenteed to be invoked only when its timeout has passed,	1201	The callback is guaranteed to be invoked only after its timeout has passed,
1135	but if multiple timers become ready during the same loop iteration then	1202	but if multiple timers become ready during the same loop iteration then
1136	order of execution is undefined.	1203	order of execution is undefined.
1137		1204
1138	=head3 Watcher-Specific Functions and Data Members	1205	=head3 Watcher-Specific Functions and Data Members
1139		1206
…		…
1141		1208
1142	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1209	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1143		1210
1144	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1211	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1145		1212
1146	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1213	Configure the timer to trigger after C<after> seconds. If C<repeat>
1147	C<0.>, then it will automatically be stopped. If it is positive, then the	1214	is C<0.>, then it will automatically be stopped once the timeout is
1148	timer will automatically be configured to trigger again C<repeat> seconds	1215	reached. If it is positive, then the timer will automatically be
1149	later, again, and again, until stopped manually.	1216	configured to trigger again C<repeat> seconds later, again, and again,
		1217	until stopped manually.
1150		1218
1151	The timer itself will do a best-effort at avoiding drift, that is, if you	1219	The timer itself will do a best-effort at avoiding drift, that is, if
1152	configure a timer to trigger every 10 seconds, then it will trigger at	1220	you configure a timer to trigger every 10 seconds, then it will normally
1153	exactly 10 second intervals. If, however, your program cannot keep up with	1221	trigger at exactly 10 second intervals. If, however, your program cannot
1154	the timer (because it takes longer than those 10 seconds to do stuff) the	1222	keep up with the timer (because it takes longer than those 10 seconds to
1155	timer will not fire more than once per event loop iteration.	1223	do stuff) the timer will not fire more than once per event loop iteration.
1156		1224
1157	=item ev_timer_again (loop)	1225	=item ev_timer_again (loop, ev_timer *)
1158		1226
1159	This will act as if the timer timed out and restart it again if it is	1227	This will act as if the timer timed out and restart it again if it is
1160	repeating. The exact semantics are:	1228	repeating. The exact semantics are:
1161		1229
1162	If the timer is pending, its pending status is cleared.	1230	If the timer is pending, its pending status is cleared.
1163		1231
1164	If the timer is started but nonrepeating, stop it (as if it timed out).	1232	If the timer is started but non-repeating, stop it (as if it timed out).
1165		1233
1166	If the timer is repeating, either start it if necessary (with the	1234	If the timer is repeating, either start it if necessary (with the
1167	C<repeat> value), or reset the running timer to the C<repeat> value.	1235	C<repeat> value), or reset the running timer to the C<repeat> value.
1168		1236
1169	This sounds a bit complicated, but here is a useful and typical	1237	This sounds a bit complicated, but here is a useful and typical
1170	example: Imagine you have a tcp connection and you want a so-called idle	1238	example: Imagine you have a TCP connection and you want a so-called idle
1171	timeout, that is, you want to be called when there have been, say, 60	1239	timeout, that is, you want to be called when there have been, say, 60
1172	seconds of inactivity on the socket. The easiest way to do this is to	1240	seconds of inactivity on the socket. The easiest way to do this is to
1173	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1241	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1174	C<ev_timer_again> each time you successfully read or write some data. If	1242	C<ev_timer_again> each time you successfully read or write some data. If
1175	you go into an idle state where you do not expect data to travel on the	1243	you go into an idle state where you do not expect data to travel on the
…		…
1201		1269
1202	=head3 Examples	1270	=head3 Examples
1203		1271
1204	Example: Create a timer that fires after 60 seconds.	1272	Example: Create a timer that fires after 60 seconds.
1205		1273
1206	static void	1274	static void
1207	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1275	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1208	{	1276	{
1209	.. one minute over, w is actually stopped right here	1277	.. one minute over, w is actually stopped right here
1210	}	1278	}
1211		1279
1212	struct ev_timer mytimer;	1280	struct ev_timer mytimer;
1213	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1281	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1214	ev_timer_start (loop, &mytimer);	1282	ev_timer_start (loop, &mytimer);
1215		1283
1216	Example: Create a timeout timer that times out after 10 seconds of	1284	Example: Create a timeout timer that times out after 10 seconds of
1217	inactivity.	1285	inactivity.
1218		1286
1219	static void	1287	static void
1220	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1288	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1221	{	1289	{
1222	.. ten seconds without any activity	1290	.. ten seconds without any activity
1223	}	1291	}
1224		1292
1225	struct ev_timer mytimer;	1293	struct ev_timer mytimer;
1226	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1294	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1227	ev_timer_again (&mytimer); /* start timer */	1295	ev_timer_again (&mytimer); /* start timer */
1228	ev_loop (loop, 0);	1296	ev_loop (loop, 0);
1229		1297
1230	// and in some piece of code that gets executed on any "activity":	1298	// and in some piece of code that gets executed on any "activity":
1231	// reset the timeout to start ticking again at 10 seconds	1299	// reset the timeout to start ticking again at 10 seconds
1232	ev_timer_again (&mytimer);	1300	ev_timer_again (&mytimer);
1233		1301
1234		1302
1235	=head2 C<ev_periodic> - to cron or not to cron?	1303	=head2 C<ev_periodic> - to cron or not to cron?
1236		1304
1237	Periodic watchers are also timers of a kind, but they are very versatile	1305	Periodic watchers are also timers of a kind, but they are very versatile
1238	(and unfortunately a bit complex).	1306	(and unfortunately a bit complex).
1239		1307
1240	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1308	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1241	but on wallclock time (absolute time). You can tell a periodic watcher	1309	but on wall clock time (absolute time). You can tell a periodic watcher
1242	to trigger "at" some specific point in time. For example, if you tell a	1310	to trigger after some specific point in time. For example, if you tell a
1243	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1311	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1244	+ 10.>) and then reset your system clock to the last year, then it will	1312	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1313	clock to January of the previous year, then it will take more than year
1245	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1314	to trigger the event (unlike an C<ev_timer>, which would still trigger
1246	roughly 10 seconds later).	1315	roughly 10 seconds later as it uses a relative timeout).
1247		1316
1248	They can also be used to implement vastly more complex timers, such as	1317	C<ev_periodic>s can also be used to implement vastly more complex timers,
1249	triggering an event on each midnight, local time or other, complicated,	1318	such as triggering an event on each "midnight, local time", or other
1250	rules.	1319	complicated, rules.
1251		1320
1252	As with timers, the callback is guarenteed to be invoked only when the	1321	As with timers, the callback is guaranteed to be invoked only when the
1253	time (C<at>) has been passed, but if multiple periodic timers become ready	1322	time (C<at>) has passed, but if multiple periodic timers become ready
1254	during the same loop iteration then order of execution is undefined.	1323	during the same loop iteration then order of execution is undefined.
1255		1324
1256	=head3 Watcher-Specific Functions and Data Members	1325	=head3 Watcher-Specific Functions and Data Members
1257		1326
1258	=over 4	1327	=over 4
…		…
1266		1335
1267	=over 4	1336	=over 4
1268		1337
1269	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1338	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1270		1339
1271	In this configuration the watcher triggers an event at the wallclock time	1340	In this configuration the watcher triggers an event after the wall clock
1272	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1341	time C<at> has passed and doesn't repeat. It will not adjust when a time
1273	that is, if it is to be run at January 1st 2011 then it will run when the	1342	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1274	system time reaches or surpasses this time.	1343	run when the system time reaches or surpasses this time.
1275		1344
1276	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1345	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1277		1346
1278	In this mode the watcher will always be scheduled to time out at the next	1347	In this mode the watcher will always be scheduled to time out at the next
1279	C<at + N * interval> time (for some integer N, which can also be negative)	1348	C<at + N * interval> time (for some integer N, which can also be negative)
1280	and then repeat, regardless of any time jumps.	1349	and then repeat, regardless of any time jumps.
1281		1350
1282	This can be used to create timers that do not drift with respect to system	1351	This can be used to create timers that do not drift with respect to system
1283	time:	1352	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1353	the hour:
1284		1354
1285	ev_periodic_set (&periodic, 0., 3600., 0);	1355	ev_periodic_set (&periodic, 0., 3600., 0);
1286		1356
1287	This doesn't mean there will always be 3600 seconds in between triggers,	1357	This doesn't mean there will always be 3600 seconds in between triggers,
1288	but only that the the callback will be called when the system time shows a	1358	but only that the callback will be called when the system time shows a
1289	full hour (UTC), or more correctly, when the system time is evenly divisible	1359	full hour (UTC), or more correctly, when the system time is evenly divisible
1290	by 3600.	1360	by 3600.
1291		1361
1292	Another way to think about it (for the mathematically inclined) is that	1362	Another way to think about it (for the mathematically inclined) is that
1293	C<ev_periodic> will try to run the callback in this mode at the next possible	1363	C<ev_periodic> will try to run the callback in this mode at the next possible
1294	time where C<time = at (mod interval)>, regardless of any time jumps.	1364	time where C<time = at (mod interval)>, regardless of any time jumps.
1295		1365
1296	For numerical stability it is preferable that the C<at> value is near	1366	For numerical stability it is preferable that the C<at> value is near
1297	C<ev_now ()> (the current time), but there is no range requirement for	1367	C<ev_now ()> (the current time), but there is no range requirement for
1298	this value.	1368	this value, and in fact is often specified as zero.
		1369
		1370	Note also that there is an upper limit to how often a timer can fire (CPU
		1371	speed for example), so if C<interval> is very small then timing stability
		1372	will of course deteriorate. Libev itself tries to be exact to be about one
		1373	millisecond (if the OS supports it and the machine is fast enough).
1299		1374
1300	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1375	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1301		1376
1302	In this mode the values for C<interval> and C<at> are both being	1377	In this mode the values for C<interval> and C<at> are both being
1303	ignored. Instead, each time the periodic watcher gets scheduled, the	1378	ignored. Instead, each time the periodic watcher gets scheduled, the
1304	reschedule callback will be called with the watcher as first, and the	1379	reschedule callback will be called with the watcher as first, and the
1305	current time as second argument.	1380	current time as second argument.
1306		1381
1307	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1382	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1308	ever, or make any event loop modifications>. If you need to stop it,	1383	ever, or make ANY event loop modifications whatsoever>.
1309	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1310	starting an C<ev_prepare> watcher, which is legal).
1311		1384
		1385	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1386	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1387	only event loop modification you are allowed to do).
		1388
1312	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1389	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1313	ev_tstamp now)>, e.g.:	1390	*w, ev_tstamp now)>, e.g.:
1314		1391
1315	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1392	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1316	{	1393	{
1317	return now + 60.;	1394	return now + 60.;
1318	}	1395	}
…		…
1320	It must return the next time to trigger, based on the passed time value	1397	It must return the next time to trigger, based on the passed time value
1321	(that is, the lowest time value larger than to the second argument). It	1398	(that is, the lowest time value larger than to the second argument). It
1322	will usually be called just before the callback will be triggered, but	1399	will usually be called just before the callback will be triggered, but
1323	might be called at other times, too.	1400	might be called at other times, too.
1324		1401
1325	NOTE: I<< This callback must always return a time that is later than the	1402	NOTE: I<< This callback must always return a time that is higher than or
1326	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1403	equal to the passed C<now> value >>.
1327		1404
1328	This can be used to create very complex timers, such as a timer that	1405	This can be used to create very complex timers, such as a timer that
1329	triggers on each midnight, local time. To do this, you would calculate the	1406	triggers on "next midnight, local time". To do this, you would calculate the
1330	next midnight after C<now> and return the timestamp value for this. How	1407	next midnight after C<now> and return the timestamp value for this. How
1331	you do this is, again, up to you (but it is not trivial, which is the main	1408	you do this is, again, up to you (but it is not trivial, which is the main
1332	reason I omitted it as an example).	1409	reason I omitted it as an example).
1333		1410
1334	=back	1411	=back
…		…
1338	Simply stops and restarts the periodic watcher again. This is only useful	1415	Simply stops and restarts the periodic watcher again. This is only useful
1339	when you changed some parameters or the reschedule callback would return	1416	when you changed some parameters or the reschedule callback would return
1340	a different time than the last time it was called (e.g. in a crond like	1417	a different time than the last time it was called (e.g. in a crond like
1341	program when the crontabs have changed).	1418	program when the crontabs have changed).
1342		1419
		1420	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1421
		1422	When active, returns the absolute time that the watcher is supposed to
		1423	trigger next.
		1424
1343	=item ev_tstamp offset [read-write]	1425	=item ev_tstamp offset [read-write]
1344		1426
1345	When repeating, this contains the offset value, otherwise this is the	1427	When repeating, this contains the offset value, otherwise this is the
1346	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1428	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1347		1429
…		…
1358		1440
1359	The current reschedule callback, or C<0>, if this functionality is	1441	The current reschedule callback, or C<0>, if this functionality is
1360	switched off. Can be changed any time, but changes only take effect when	1442	switched off. Can be changed any time, but changes only take effect when
1361	the periodic timer fires or C<ev_periodic_again> is being called.	1443	the periodic timer fires or C<ev_periodic_again> is being called.
1362		1444
1363	=item ev_tstamp at [read-only]
1364
1365	When active, contains the absolute time that the watcher is supposed to
1366	trigger next.
1367
1368	=back	1445	=back
1369		1446
1370	=head3 Examples	1447	=head3 Examples
1371		1448
1372	Example: Call a callback every hour, or, more precisely, whenever the	1449	Example: Call a callback every hour, or, more precisely, whenever the
1373	system clock is divisible by 3600. The callback invocation times have	1450	system clock is divisible by 3600. The callback invocation times have
1374	potentially a lot of jittering, but good long-term stability.	1451	potentially a lot of jitter, but good long-term stability.
1375		1452
1376	static void	1453	static void
1377	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1454	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1378	{	1455	{
1379	... its now a full hour (UTC, or TAI or whatever your clock follows)	1456	... its now a full hour (UTC, or TAI or whatever your clock follows)
1380	}	1457	}
1381		1458
1382	struct ev_periodic hourly_tick;	1459	struct ev_periodic hourly_tick;
1383	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1460	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1384	ev_periodic_start (loop, &hourly_tick);	1461	ev_periodic_start (loop, &hourly_tick);
1385		1462
1386	Example: The same as above, but use a reschedule callback to do it:	1463	Example: The same as above, but use a reschedule callback to do it:
1387		1464
1388	#include <math.h>	1465	#include <math.h>
1389		1466
1390	static ev_tstamp	1467	static ev_tstamp
1391	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1468	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1392	{	1469	{
1393	return fmod (now, 3600.) + 3600.;	1470	return fmod (now, 3600.) + 3600.;
1394	}	1471	}
1395		1472
1396	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1473	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1397		1474
1398	Example: Call a callback every hour, starting now:	1475	Example: Call a callback every hour, starting now:
1399		1476
1400	struct ev_periodic hourly_tick;	1477	struct ev_periodic hourly_tick;
1401	ev_periodic_init (&hourly_tick, clock_cb,	1478	ev_periodic_init (&hourly_tick, clock_cb,
1402	fmod (ev_now (loop), 3600.), 3600., 0);	1479	fmod (ev_now (loop), 3600.), 3600., 0);
1403	ev_periodic_start (loop, &hourly_tick);	1480	ev_periodic_start (loop, &hourly_tick);
1404		1481
1405		1482
1406	=head2 C<ev_signal> - signal me when a signal gets signalled!	1483	=head2 C<ev_signal> - signal me when a signal gets signalled!
1407		1484
1408	Signal watchers will trigger an event when the process receives a specific	1485	Signal watchers will trigger an event when the process receives a specific
…		…
1415	with the kernel (thus it coexists with your own signal handlers as long	1492	with the kernel (thus it coexists with your own signal handlers as long
1416	as you don't register any with libev). Similarly, when the last signal	1493	as you don't register any with libev). Similarly, when the last signal
1417	watcher for a signal is stopped libev will reset the signal handler to	1494	watcher for a signal is stopped libev will reset the signal handler to
1418	SIG_DFL (regardless of what it was set to before).	1495	SIG_DFL (regardless of what it was set to before).
1419		1496
		1497	If possible and supported, libev will install its handlers with
		1498	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
		1499	interrupted. If you have a problem with system calls getting interrupted by
		1500	signals you can block all signals in an C<ev_check> watcher and unblock
		1501	them in an C<ev_prepare> watcher.
		1502
1420	=head3 Watcher-Specific Functions and Data Members	1503	=head3 Watcher-Specific Functions and Data Members
1421		1504
1422	=over 4	1505	=over 4
1423		1506
1424	=item ev_signal_init (ev_signal *, callback, int signum)	1507	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
1432		1515
1433	The signal the watcher watches out for.	1516	The signal the watcher watches out for.
1434		1517
1435	=back	1518	=back
1436		1519
		1520	=head3 Examples
		1521
		1522	Example: Try to exit cleanly on SIGINT and SIGTERM.
		1523
		1524	static void
		1525	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
		1526	{
		1527	ev_unloop (loop, EVUNLOOP_ALL);
		1528	}
		1529
		1530	struct ev_signal signal_watcher;
		1531	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
		1532	ev_signal_start (loop, &sigint_cb);
		1533
1437		1534
1438	=head2 C<ev_child> - watch out for process status changes	1535	=head2 C<ev_child> - watch out for process status changes
1439		1536
1440	Child watchers trigger when your process receives a SIGCHLD in response to	1537	Child watchers trigger when your process receives a SIGCHLD in response to
1441	some child status changes (most typically when a child of yours dies).	1538	some child status changes (most typically when a child of yours dies). It
		1539	is permissible to install a child watcher I<after> the child has been
		1540	forked (which implies it might have already exited), as long as the event
		1541	loop isn't entered (or is continued from a watcher).
		1542
		1543	Only the default event loop is capable of handling signals, and therefore
		1544	you can only register child watchers in the default event loop.
		1545
		1546	=head3 Process Interaction
		1547
		1548	Libev grabs C<SIGCHLD> as soon as the default event loop is
		1549	initialised. This is necessary to guarantee proper behaviour even if
		1550	the first child watcher is started after the child exits. The occurrence
		1551	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
		1552	synchronously as part of the event loop processing. Libev always reaps all
		1553	children, even ones not watched.
		1554
		1555	=head3 Overriding the Built-In Processing
		1556
		1557	Libev offers no special support for overriding the built-in child
		1558	processing, but if your application collides with libev's default child
		1559	handler, you can override it easily by installing your own handler for
		1560	C<SIGCHLD> after initialising the default loop, and making sure the
		1561	default loop never gets destroyed. You are encouraged, however, to use an
		1562	event-based approach to child reaping and thus use libev's support for
		1563	that, so other libev users can use C<ev_child> watchers freely.
1442		1564
1443	=head3 Watcher-Specific Functions and Data Members	1565	=head3 Watcher-Specific Functions and Data Members
1444		1566
1445	=over 4	1567	=over 4
1446		1568
…		…
1472		1594
1473	=back	1595	=back
1474		1596
1475	=head3 Examples	1597	=head3 Examples
1476		1598
1477	Example: Try to exit cleanly on SIGINT and SIGTERM.	1599	Example: C<fork()> a new process and install a child handler to wait for
		1600	its completion.
1478		1601
		1602	ev_child cw;
		1603
1479	static void	1604	static void
1480	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1605	child_cb (EV_P_ struct ev_child *w, int revents)
1481	{	1606	{
1482	ev_unloop (loop, EVUNLOOP_ALL);	1607	ev_child_stop (EV_A_ w);
		1608	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1483	}	1609	}
1484		1610
1485	struct ev_signal signal_watcher;	1611	pid_t pid = fork ();
1486	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1612
1487	ev_signal_start (loop, &sigint_cb);	1613	if (pid < 0)
		1614	// error
		1615	else if (pid == 0)
		1616	{
		1617	// the forked child executes here
		1618	exit (1);
		1619	}
		1620	else
		1621	{
		1622	ev_child_init (&cw, child_cb, pid, 0);
		1623	ev_child_start (EV_DEFAULT_ &cw);
		1624	}
1488		1625
1489		1626
1490	=head2 C<ev_stat> - did the file attributes just change?	1627	=head2 C<ev_stat> - did the file attributes just change?
1491		1628
1492	This watches a filesystem path for attribute changes. That is, it calls	1629	This watches a file system path for attribute changes. That is, it calls
1493	C<stat> regularly (or when the OS says it changed) and sees if it changed	1630	C<stat> regularly (or when the OS says it changed) and sees if it changed
1494	compared to the last time, invoking the callback if it did.	1631	compared to the last time, invoking the callback if it did.
1495		1632
1496	The path does not need to exist: changing from "path exists" to "path does	1633	The path does not need to exist: changing from "path exists" to "path does
1497	not exist" is a status change like any other. The condition "path does	1634	not exist" is a status change like any other. The condition "path does
…		…
1515	as even with OS-supported change notifications, this can be	1652	as even with OS-supported change notifications, this can be
1516	resource-intensive.	1653	resource-intensive.
1517		1654
1518	At the time of this writing, only the Linux inotify interface is	1655	At the time of this writing, only the Linux inotify interface is
1519	implemented (implementing kqueue support is left as an exercise for the	1656	implemented (implementing kqueue support is left as an exercise for the
		1657	reader, note, however, that the author sees no way of implementing ev_stat
1520	reader). Inotify will be used to give hints only and should not change the	1658	semantics with kqueue). Inotify will be used to give hints only and should
1521	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1659	not change the semantics of C<ev_stat> watchers, which means that libev
1522	to fall back to regular polling again even with inotify, but changes are	1660	sometimes needs to fall back to regular polling again even with inotify,
1523	usually detected immediately, and if the file exists there will be no	1661	but changes are usually detected immediately, and if the file exists there
1524	polling.	1662	will be no polling.
		1663
		1664	=head3 ABI Issues (Largefile Support)
		1665
		1666	Libev by default (unless the user overrides this) uses the default
		1667	compilation environment, which means that on systems with large file
		1668	support disabled by default, you get the 32 bit version of the stat
		1669	structure. When using the library from programs that change the ABI to
		1670	use 64 bit file offsets the programs will fail. In that case you have to
		1671	compile libev with the same flags to get binary compatibility. This is
		1672	obviously the case with any flags that change the ABI, but the problem is
		1673	most noticeably disabled with ev_stat and large file support.
		1674
		1675	The solution for this is to lobby your distribution maker to make large
		1676	file interfaces available by default (as e.g. FreeBSD does) and not
		1677	optional. Libev cannot simply switch on large file support because it has
		1678	to exchange stat structures with application programs compiled using the
		1679	default compilation environment.
1525		1680
1526	=head3 Inotify	1681	=head3 Inotify
1527		1682
1528	When C<inotify (7)> support has been compiled into libev (generally only	1683	When C<inotify (7)> support has been compiled into libev (generally only
1529	available on Linux) and present at runtime, it will be used to speed up	1684	available on Linux) and present at runtime, it will be used to speed up
1530	change detection where possible. The inotify descriptor will be created lazily	1685	change detection where possible. The inotify descriptor will be created lazily
1531	when the first C<ev_stat> watcher is being started.	1686	when the first C<ev_stat> watcher is being started.
1532		1687
1533	Inotify presense does not change the semantics of C<ev_stat> watchers	1688	Inotify presence does not change the semantics of C<ev_stat> watchers
1534	except that changes might be detected earlier, and in some cases, to avoid	1689	except that changes might be detected earlier, and in some cases, to avoid
1535	making regular C<stat> calls. Even in the presense of inotify support	1690	making regular C<stat> calls. Even in the presence of inotify support
1536	there are many cases where libev has to resort to regular C<stat> polling.	1691	there are many cases where libev has to resort to regular C<stat> polling.
1537		1692
1538	(There is no support for kqueue, as apparently it cannot be used to	1693	(There is no support for kqueue, as apparently it cannot be used to
1539	implement this functionality, due to the requirement of having a file	1694	implement this functionality, due to the requirement of having a file
1540	descriptor open on the object at all times).	1695	descriptor open on the object at all times).
1541		1696
1542	=head3 The special problem of stat time resolution	1697	=head3 The special problem of stat time resolution
1543		1698
1544	The C<stat ()> syscall only supports full-second resolution portably, and	1699	The C<stat ()> system call only supports full-second resolution portably, and
1545	even on systems where the resolution is higher, many filesystems still	1700	even on systems where the resolution is higher, many file systems still
1546	only support whole seconds.	1701	only support whole seconds.
1547		1702
1548	That means that, if the time is the only thing that changes, you might	1703	That means that, if the time is the only thing that changes, you can
1549	miss updates: on the first update, C<ev_stat> detects a change and calls	1704	easily miss updates: on the first update, C<ev_stat> detects a change and
1550	your callback, which does something. When there is another update within	1705	calls your callback, which does something. When there is another update
1551	the same second, C<ev_stat> will be unable to detect it.	1706	within the same second, C<ev_stat> will be unable to detect it as the stat
		1707	data does not change.
1552		1708
1553	The solution to this is to delay acting on a change for a second (or till	1709	The solution to this is to delay acting on a change for slightly more
1554	the next second boundary), using a roughly one-second delay C<ev_timer>	1710	than a second (or till slightly after the next full second boundary), using
1555	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1711	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1556	is added to work around small timing inconsistencies of some operating	1712	ev_timer_again (loop, w)>).
1557	systems.	1713
		1714	The C<.02> offset is added to work around small timing inconsistencies
		1715	of some operating systems (where the second counter of the current time
		1716	might be be delayed. One such system is the Linux kernel, where a call to
		1717	C<gettimeofday> might return a timestamp with a full second later than
		1718	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1719	update file times then there will be a small window where the kernel uses
		1720	the previous second to update file times but libev might already execute
		1721	the timer callback).
1558		1722
1559	=head3 Watcher-Specific Functions and Data Members	1723	=head3 Watcher-Specific Functions and Data Members
1560		1724
1561	=over 4	1725	=over 4
1562		1726
…		…
1568	C<path>. The C<interval> is a hint on how quickly a change is expected to	1732	C<path>. The C<interval> is a hint on how quickly a change is expected to
1569	be detected and should normally be specified as C<0> to let libev choose	1733	be detected and should normally be specified as C<0> to let libev choose
1570	a suitable value. The memory pointed to by C<path> must point to the same	1734	a suitable value. The memory pointed to by C<path> must point to the same
1571	path for as long as the watcher is active.	1735	path for as long as the watcher is active.
1572		1736
1573	The callback will be receive C<EV_STAT> when a change was detected,	1737	The callback will receive C<EV_STAT> when a change was detected, relative
1574	relative to the attributes at the time the watcher was started (or the	1738	to the attributes at the time the watcher was started (or the last change
1575	last change was detected).	1739	was detected).
1576		1740
1577	=item ev_stat_stat (ev_stat *)	1741	=item ev_stat_stat (loop, ev_stat *)
1578		1742
1579	Updates the stat buffer immediately with new values. If you change the	1743	Updates the stat buffer immediately with new values. If you change the
1580	watched path in your callback, you could call this fucntion to avoid	1744	watched path in your callback, you could call this function to avoid
1581	detecting this change (while introducing a race condition). Can also be	1745	detecting this change (while introducing a race condition if you are not
1582	useful simply to find out the new values.	1746	the only one changing the path). Can also be useful simply to find out the
		1747	new values.
1583		1748
1584	=item ev_statdata attr [read-only]	1749	=item ev_statdata attr [read-only]
1585		1750
1586	The most-recently detected attributes of the file. Although the type is of	1751	The most-recently detected attributes of the file. Although the type is
1587	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1752	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1588	suitable for your system. If the C<st_nlink> member is C<0>, then there	1753	suitable for your system, but you can only rely on the POSIX-standardised
		1754	members to be present. If the C<st_nlink> member is C<0>, then there was
1589	was some error while C<stat>ing the file.	1755	some error while C<stat>ing the file.
1590		1756
1591	=item ev_statdata prev [read-only]	1757	=item ev_statdata prev [read-only]
1592		1758
1593	The previous attributes of the file. The callback gets invoked whenever	1759	The previous attributes of the file. The callback gets invoked whenever
1594	C<prev> != C<attr>.	1760	C<prev> != C<attr>, or, more precisely, one or more of these members
		1761	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1762	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1595		1763
1596	=item ev_tstamp interval [read-only]	1764	=item ev_tstamp interval [read-only]
1597		1765
1598	The specified interval.	1766	The specified interval.
1599		1767
1600	=item const char *path [read-only]	1768	=item const char *path [read-only]
1601		1769
1602	The filesystem path that is being watched.	1770	The file system path that is being watched.
1603		1771
1604	=back	1772	=back
1605		1773
1606	=head3 Examples	1774	=head3 Examples
1607		1775
1608	Example: Watch C</etc/passwd> for attribute changes.	1776	Example: Watch C</etc/passwd> for attribute changes.
1609		1777
1610	static void	1778	static void
1611	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1779	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1612	{	1780	{
1613	/* /etc/passwd changed in some way */	1781	/* /etc/passwd changed in some way */
1614	if (w->attr.st_nlink)	1782	if (w->attr.st_nlink)
1615	{	1783	{
1616	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1784	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1617	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1785	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1618	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1786	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1619	}	1787	}
1620	else	1788	else
1621	/* you shalt not abuse printf for puts */	1789	/* you shalt not abuse printf for puts */
1622	puts ("wow, /etc/passwd is not there, expect problems. "	1790	puts ("wow, /etc/passwd is not there, expect problems. "
1623	"if this is windows, they already arrived\n");	1791	"if this is windows, they already arrived\n");
1624	}	1792	}
1625		1793
1626	...	1794	...
1627	ev_stat passwd;	1795	ev_stat passwd;
1628		1796
1629	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1797	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1630	ev_stat_start (loop, &passwd);	1798	ev_stat_start (loop, &passwd);
1631		1799
1632	Example: Like above, but additionally use a one-second delay so we do not	1800	Example: Like above, but additionally use a one-second delay so we do not
1633	miss updates (however, frequent updates will delay processing, too, so	1801	miss updates (however, frequent updates will delay processing, too, so
1634	one might do the work both on C<ev_stat> callback invocation I<and> on	1802	one might do the work both on C<ev_stat> callback invocation I<and> on
1635	C<ev_timer> callback invocation).	1803	C<ev_timer> callback invocation).
1636		1804
1637	static ev_stat passwd;	1805	static ev_stat passwd;
1638	static ev_timer timer;	1806	static ev_timer timer;
1639		1807
1640	static void	1808	static void
1641	timer_cb (EV_P_ ev_timer *w, int revents)	1809	timer_cb (EV_P_ ev_timer *w, int revents)
1642	{	1810	{
1643	ev_timer_stop (EV_A_ w);	1811	ev_timer_stop (EV_A_ w);
1644		1812
1645	/* now it's one second after the most recent passwd change */	1813	/* now it's one second after the most recent passwd change */
1646	}	1814	}
1647		1815
1648	static void	1816	static void
1649	stat_cb (EV_P_ ev_stat *w, int revents)	1817	stat_cb (EV_P_ ev_stat *w, int revents)
1650	{	1818	{
1651	/* reset the one-second timer */	1819	/* reset the one-second timer */
1652	ev_timer_again (EV_A_ &timer);	1820	ev_timer_again (EV_A_ &timer);
1653	}	1821	}
1654		1822
1655	...	1823	...
1656	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1824	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1657	ev_stat_start (loop, &passwd);	1825	ev_stat_start (loop, &passwd);
1658	ev_timer_init (&timer, timer_cb, 0., 1.01);	1826	ev_timer_init (&timer, timer_cb, 0., 1.02);
1659		1827
1660		1828
1661	=head2 C<ev_idle> - when you've got nothing better to do...	1829	=head2 C<ev_idle> - when you've got nothing better to do...
1662		1830
1663	Idle watchers trigger events when no other events of the same or higher	1831	Idle watchers trigger events when no other events of the same or higher
…		…
1694	=head3 Examples	1862	=head3 Examples
1695		1863
1696	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1864	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1697	callback, free it. Also, use no error checking, as usual.	1865	callback, free it. Also, use no error checking, as usual.
1698		1866
1699	static void	1867	static void
1700	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1868	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1701	{	1869	{
1702	free (w);	1870	free (w);
1703	// now do something you wanted to do when the program has	1871	// now do something you wanted to do when the program has
1704	// no longer anything immediate to do.	1872	// no longer anything immediate to do.
1705	}	1873	}
1706		1874
1707	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1875	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1708	ev_idle_init (idle_watcher, idle_cb);	1876	ev_idle_init (idle_watcher, idle_cb);
1709	ev_idle_start (loop, idle_cb);	1877	ev_idle_start (loop, idle_cb);
1710		1878
1711		1879
1712	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1880	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1713		1881
1714	Prepare and check watchers are usually (but not always) used in tandem:	1882	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1733		1901
1734	This is done by examining in each prepare call which file descriptors need	1902	This is done by examining in each prepare call which file descriptors need
1735	to be watched by the other library, registering C<ev_io> watchers for	1903	to be watched by the other library, registering C<ev_io> watchers for
1736	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1904	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1737	provide just this functionality). Then, in the check watcher you check for	1905	provide just this functionality). Then, in the check watcher you check for
1738	any events that occured (by checking the pending status of all watchers	1906	any events that occurred (by checking the pending status of all watchers
1739	and stopping them) and call back into the library. The I/O and timer	1907	and stopping them) and call back into the library. The I/O and timer
1740	callbacks will never actually be called (but must be valid nevertheless,	1908	callbacks will never actually be called (but must be valid nevertheless,
1741	because you never know, you know?).	1909	because you never know, you know?).
1742		1910
1743	As another example, the Perl Coro module uses these hooks to integrate	1911	As another example, the Perl Coro module uses these hooks to integrate
…		…
1751		1919
1752	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1920	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1753	priority, to ensure that they are being run before any other watchers	1921	priority, to ensure that they are being run before any other watchers
1754	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1922	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1755	too) should not activate ("feed") events into libev. While libev fully	1923	too) should not activate ("feed") events into libev. While libev fully
1756	supports this, they will be called before other C<ev_check> watchers	1924	supports this, they might get executed before other C<ev_check> watchers
1757	did their job. As C<ev_check> watchers are often used to embed other	1925	did their job. As C<ev_check> watchers are often used to embed other
1758	(non-libev) event loops those other event loops might be in an unusable	1926	(non-libev) event loops those other event loops might be in an unusable
1759	state until their C<ev_check> watcher ran (always remind yourself to	1927	state until their C<ev_check> watcher ran (always remind yourself to
1760	coexist peacefully with others).	1928	coexist peacefully with others).
1761		1929
…		…
1776	=head3 Examples	1944	=head3 Examples
1777		1945
1778	There are a number of principal ways to embed other event loops or modules	1946	There are a number of principal ways to embed other event loops or modules
1779	into libev. Here are some ideas on how to include libadns into libev	1947	into libev. Here are some ideas on how to include libadns into libev
1780	(there is a Perl module named C<EV::ADNS> that does this, which you could	1948	(there is a Perl module named C<EV::ADNS> that does this, which you could
1781	use for an actually working example. Another Perl module named C<EV::Glib>	1949	use as a working example. Another Perl module named C<EV::Glib> embeds a
1782	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	1950	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1783	into the Glib event loop).	1951	Glib event loop).
1784		1952
1785	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1953	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1786	and in a check watcher, destroy them and call into libadns. What follows	1954	and in a check watcher, destroy them and call into libadns. What follows
1787	is pseudo-code only of course. This requires you to either use a low	1955	is pseudo-code only of course. This requires you to either use a low
1788	priority for the check watcher or use C<ev_clear_pending> explicitly, as	1956	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1789	the callbacks for the IO/timeout watchers might not have been called yet.	1957	the callbacks for the IO/timeout watchers might not have been called yet.
1790		1958
1791	static ev_io iow [nfd];	1959	static ev_io iow [nfd];
1792	static ev_timer tw;	1960	static ev_timer tw;
1793		1961
1794	static void	1962	static void
1795	io_cb (ev_loop *loop, ev_io *w, int revents)	1963	io_cb (ev_loop *loop, ev_io *w, int revents)
1796	{	1964	{
1797	}	1965	}
1798		1966
1799	// create io watchers for each fd and a timer before blocking	1967	// create io watchers for each fd and a timer before blocking
1800	static void	1968	static void
1801	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1969	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1802	{	1970	{
1803	int timeout = 3600000;	1971	int timeout = 3600000;
1804	struct pollfd fds [nfd];	1972	struct pollfd fds [nfd];
1805	// actual code will need to loop here and realloc etc.	1973	// actual code will need to loop here and realloc etc.
1806	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1974	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1807		1975
1808	/* the callback is illegal, but won't be called as we stop during check */	1976	/* the callback is illegal, but won't be called as we stop during check */
1809	ev_timer_init (&tw, 0, timeout * 1e-3);	1977	ev_timer_init (&tw, 0, timeout * 1e-3);
1810	ev_timer_start (loop, &tw);	1978	ev_timer_start (loop, &tw);
1811		1979
1812	// create one ev_io per pollfd	1980	// create one ev_io per pollfd
1813	for (int i = 0; i < nfd; ++i)	1981	for (int i = 0; i < nfd; ++i)
1814	{	1982	{
1815	ev_io_init (iow + i, io_cb, fds [i].fd,	1983	ev_io_init (iow + i, io_cb, fds [i].fd,
1816	((fds [i].events & POLLIN ? EV_READ : 0)	1984	((fds [i].events & POLLIN ? EV_READ : 0)
1817	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1985	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1818		1986
1819	fds [i].revents = 0;	1987	fds [i].revents = 0;
1820	ev_io_start (loop, iow + i);	1988	ev_io_start (loop, iow + i);
1821	}	1989	}
1822	}	1990	}
1823		1991
1824	// stop all watchers after blocking	1992	// stop all watchers after blocking
1825	static void	1993	static void
1826	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1994	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1827	{	1995	{
1828	ev_timer_stop (loop, &tw);	1996	ev_timer_stop (loop, &tw);
1829		1997
1830	for (int i = 0; i < nfd; ++i)	1998	for (int i = 0; i < nfd; ++i)
1831	{	1999	{
1832	// set the relevant poll flags	2000	// set the relevant poll flags
1833	// could also call adns_processreadable etc. here	2001	// could also call adns_processreadable etc. here
1834	struct pollfd *fd = fds + i;	2002	struct pollfd *fd = fds + i;
1835	int revents = ev_clear_pending (iow + i);	2003	int revents = ev_clear_pending (iow + i);
1836	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2004	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1837	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2005	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1838		2006
1839	// now stop the watcher	2007	// now stop the watcher
1840	ev_io_stop (loop, iow + i);	2008	ev_io_stop (loop, iow + i);
1841	}	2009	}
1842		2010
1843	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2011	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1844	}	2012	}
1845		2013
1846	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2014	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1847	in the prepare watcher and would dispose of the check watcher.	2015	in the prepare watcher and would dispose of the check watcher.
1848		2016
1849	Method 3: If the module to be embedded supports explicit event	2017	Method 3: If the module to be embedded supports explicit event
1850	notification (adns does), you can also make use of the actual watcher	2018	notification (libadns does), you can also make use of the actual watcher
1851	callbacks, and only destroy/create the watchers in the prepare watcher.	2019	callbacks, and only destroy/create the watchers in the prepare watcher.
1852		2020
1853	static void	2021	static void
1854	timer_cb (EV_P_ ev_timer *w, int revents)	2022	timer_cb (EV_P_ ev_timer *w, int revents)
1855	{	2023	{
1856	adns_state ads = (adns_state)w->data;	2024	adns_state ads = (adns_state)w->data;
1857	update_now (EV_A);	2025	update_now (EV_A);
1858		2026
1859	adns_processtimeouts (ads, &tv_now);	2027	adns_processtimeouts (ads, &tv_now);
1860	}	2028	}
1861		2029
1862	static void	2030	static void
1863	io_cb (EV_P_ ev_io *w, int revents)	2031	io_cb (EV_P_ ev_io *w, int revents)
1864	{	2032	{
1865	adns_state ads = (adns_state)w->data;	2033	adns_state ads = (adns_state)w->data;
1866	update_now (EV_A);	2034	update_now (EV_A);
1867		2035
1868	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2036	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1869	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2037	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1870	}	2038	}
1871		2039
1872	// do not ever call adns_afterpoll	2040	// do not ever call adns_afterpoll
1873		2041
1874	Method 4: Do not use a prepare or check watcher because the module you	2042	Method 4: Do not use a prepare or check watcher because the module you
1875	want to embed is too inflexible to support it. Instead, youc na override	2043	want to embed is too inflexible to support it. Instead, you can override
1876	their poll function. The drawback with this solution is that the main	2044	their poll function. The drawback with this solution is that the main
1877	loop is now no longer controllable by EV. The C<Glib::EV> module does	2045	loop is now no longer controllable by EV. The C<Glib::EV> module does
1878	this.	2046	this.
1879		2047
1880	static gint	2048	static gint
1881	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2049	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1882	{	2050	{
1883	int got_events = 0;	2051	int got_events = 0;
1884		2052
1885	for (n = 0; n < nfds; ++n)	2053	for (n = 0; n < nfds; ++n)
1886	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2054	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1887		2055
1888	if (timeout >= 0)	2056	if (timeout >= 0)
1889	// create/start timer	2057	// create/start timer
1890		2058
1891	// poll	2059	// poll
1892	ev_loop (EV_A_ 0);	2060	ev_loop (EV_A_ 0);
1893		2061
1894	// stop timer again	2062	// stop timer again
1895	if (timeout >= 0)	2063	if (timeout >= 0)
1896	ev_timer_stop (EV_A_ &to);	2064	ev_timer_stop (EV_A_ &to);
1897		2065
1898	// stop io watchers again - their callbacks should have set	2066	// stop io watchers again - their callbacks should have set
1899	for (n = 0; n < nfds; ++n)	2067	for (n = 0; n < nfds; ++n)
1900	ev_io_stop (EV_A_ iow [n]);	2068	ev_io_stop (EV_A_ iow [n]);
1901		2069
1902	return got_events;	2070	return got_events;
1903	}	2071	}
1904		2072
1905		2073
1906	=head2 C<ev_embed> - when one backend isn't enough...	2074	=head2 C<ev_embed> - when one backend isn't enough...
1907		2075
1908	This is a rather advanced watcher type that lets you embed one event loop	2076	This is a rather advanced watcher type that lets you embed one event loop
…		…
1964		2132
1965	Configures the watcher to embed the given loop, which must be	2133	Configures the watcher to embed the given loop, which must be
1966	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	2134	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
1967	invoked automatically, otherwise it is the responsibility of the callback	2135	invoked automatically, otherwise it is the responsibility of the callback
1968	to invoke it (it will continue to be called until the sweep has been done,	2136	to invoke it (it will continue to be called until the sweep has been done,
1969	if you do not want thta, you need to temporarily stop the embed watcher).	2137	if you do not want that, you need to temporarily stop the embed watcher).
1970		2138
1971	=item ev_embed_sweep (loop, ev_embed *)	2139	=item ev_embed_sweep (loop, ev_embed *)
1972		2140
1973	Make a single, non-blocking sweep over the embedded loop. This works	2141	Make a single, non-blocking sweep over the embedded loop. This works
1974	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2142	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1975	apropriate way for embedded loops.	2143	appropriate way for embedded loops.
1976		2144
1977	=item struct ev_loop *other [read-only]	2145	=item struct ev_loop *other [read-only]
1978		2146
1979	The embedded event loop.	2147	The embedded event loop.
1980		2148
…		…
1982		2150
1983	=head3 Examples	2151	=head3 Examples
1984		2152
1985	Example: Try to get an embeddable event loop and embed it into the default	2153	Example: Try to get an embeddable event loop and embed it into the default
1986	event loop. If that is not possible, use the default loop. The default	2154	event loop. If that is not possible, use the default loop. The default
1987	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2155	loop is stored in C<loop_hi>, while the embeddable loop is stored in
1988	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2156	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
1989	used).	2157	used).
1990		2158
1991	struct ev_loop *loop_hi = ev_default_init (0);	2159	struct ev_loop *loop_hi = ev_default_init (0);
1992	struct ev_loop *loop_lo = 0;	2160	struct ev_loop *loop_lo = 0;
1993	struct ev_embed embed;	2161	struct ev_embed embed;
1994		2162
1995	// see if there is a chance of getting one that works	2163	// see if there is a chance of getting one that works
1996	// (remember that a flags value of 0 means autodetection)	2164	// (remember that a flags value of 0 means autodetection)
1997	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2165	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
1998	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2166	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
1999	: 0;	2167	: 0;
2000		2168
2001	// if we got one, then embed it, otherwise default to loop_hi	2169	// if we got one, then embed it, otherwise default to loop_hi
2002	if (loop_lo)	2170	if (loop_lo)
2003	{	2171	{
2004	ev_embed_init (&embed, 0, loop_lo);	2172	ev_embed_init (&embed, 0, loop_lo);
2005	ev_embed_start (loop_hi, &embed);	2173	ev_embed_start (loop_hi, &embed);
2006	}	2174	}
2007	else	2175	else
2008	loop_lo = loop_hi;	2176	loop_lo = loop_hi;
2009		2177
2010	Example: Check if kqueue is available but not recommended and create	2178	Example: Check if kqueue is available but not recommended and create
2011	a kqueue backend for use with sockets (which usually work with any	2179	a kqueue backend for use with sockets (which usually work with any
2012	kqueue implementation). Store the kqueue/socket-only event loop in	2180	kqueue implementation). Store the kqueue/socket-only event loop in
2013	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2181	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2014		2182
2015	struct ev_loop *loop = ev_default_init (0);	2183	struct ev_loop *loop = ev_default_init (0);
2016	struct ev_loop *loop_socket = 0;	2184	struct ev_loop *loop_socket = 0;
2017	struct ev_embed embed;	2185	struct ev_embed embed;
2018		2186
2019	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2187	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2020	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2188	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2021	{	2189	{
2022	ev_embed_init (&embed, 0, loop_socket);	2190	ev_embed_init (&embed, 0, loop_socket);
2023	ev_embed_start (loop, &embed);	2191	ev_embed_start (loop, &embed);
2024	}	2192	}
2025		2193
2026	if (!loop_socket)	2194	if (!loop_socket)
2027	loop_socket = loop;	2195	loop_socket = loop;
2028		2196
2029	// now use loop_socket for all sockets, and loop for everything else	2197	// now use loop_socket for all sockets, and loop for everything else
2030		2198
2031		2199
2032	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2200	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2033		2201
2034	Fork watchers are called when a C<fork ()> was detected (usually because	2202	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2087		2255
2088	=item queueing from a signal handler context	2256	=item queueing from a signal handler context
2089		2257
2090	To implement race-free queueing, you simply add to the queue in the signal	2258	To implement race-free queueing, you simply add to the queue in the signal
2091	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2259	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2092	some fictitiuous SIGUSR1 handler:	2260	some fictitious SIGUSR1 handler:
2093		2261
2094	static ev_async mysig;	2262	static ev_async mysig;
2095		2263
2096	static void	2264	static void
2097	sigusr1_handler (void)	2265	sigusr1_handler (void)
2098	{	2266	{
2099	sometype data;	2267	sometype data;
2100		2268
2101	// no locking etc.	2269	// no locking etc.
2102	queue_put (data);	2270	queue_put (data);
2103	ev_async_send (DEFAULT_ &mysig);	2271	ev_async_send (EV_DEFAULT_ &mysig);
2104	}	2272	}
2105		2273
2106	static void	2274	static void
2107	mysig_cb (EV_P_ ev_async *w, int revents)	2275	mysig_cb (EV_P_ ev_async *w, int revents)
2108	{	2276	{
…		…
2139	// only need to lock the actual queueing operation	2307	// only need to lock the actual queueing operation
2140	pthread_mutex_lock (&mymutex);	2308	pthread_mutex_lock (&mymutex);
2141	queue_put (data);	2309	queue_put (data);
2142	pthread_mutex_unlock (&mymutex);	2310	pthread_mutex_unlock (&mymutex);
2143		2311
2144	ev_async_send (DEFAULT_ &mysig);	2312	ev_async_send (EV_DEFAULT_ &mysig);
2145	}	2313	}
2146		2314
2147	static void	2315	static void
2148	mysig_cb (EV_P_ ev_async *w, int revents)	2316	mysig_cb (EV_P_ ev_async *w, int revents)
2149	{	2317	{
…		…
2171	=item ev_async_send (loop, ev_async *)	2339	=item ev_async_send (loop, ev_async *)
2172		2340
2173	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2341	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2174	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2342	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2175	C<ev_feed_event>, this call is safe to do in other threads, signal or	2343	C<ev_feed_event>, this call is safe to do in other threads, signal or
2176	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2344	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2177	section below on what exactly this means).	2345	section below on what exactly this means).
2178		2346
2179	This call incurs the overhead of a syscall only once per loop iteration,	2347	This call incurs the overhead of a system call only once per loop iteration,
2180	so while the overhead might be noticable, it doesn't apply to repeated	2348	so while the overhead might be noticeable, it doesn't apply to repeated
2181	calls to C<ev_async_send>.	2349	calls to C<ev_async_send>.
		2350
		2351	=item bool = ev_async_pending (ev_async *)
		2352
		2353	Returns a non-zero value when C<ev_async_send> has been called on the
		2354	watcher but the event has not yet been processed (or even noted) by the
		2355	event loop.
		2356
		2357	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
		2358	the loop iterates next and checks for the watcher to have become active,
		2359	it will reset the flag again. C<ev_async_pending> can be used to very
		2360	quickly check whether invoking the loop might be a good idea.
		2361
		2362	Not that this does I<not> check whether the watcher itself is pending, only
		2363	whether it has been requested to make this watcher pending.
2182		2364
2183	=back	2365	=back
2184		2366
2185		2367
2186	=head1 OTHER FUNCTIONS	2368	=head1 OTHER FUNCTIONS
…		…
2197	or timeout without having to allocate/configure/start/stop/free one or	2379	or timeout without having to allocate/configure/start/stop/free one or
2198	more watchers yourself.	2380	more watchers yourself.
2199		2381
2200	If C<fd> is less than 0, then no I/O watcher will be started and events	2382	If C<fd> is less than 0, then no I/O watcher will be started and events
2201	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2383	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2202	C<events> set will be craeted and started.	2384	C<events> set will be created and started.
2203		2385
2204	If C<timeout> is less than 0, then no timeout watcher will be	2386	If C<timeout> is less than 0, then no timeout watcher will be
2205	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2387	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2206	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2388	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2207	dubious value.	2389	dubious value.
…		…
2209	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2391	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2210	passed an C<revents> set like normal event callbacks (a combination of	2392	passed an C<revents> set like normal event callbacks (a combination of
2211	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2393	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2212	value passed to C<ev_once>:	2394	value passed to C<ev_once>:
2213		2395
2214	static void stdin_ready (int revents, void *arg)	2396	static void stdin_ready (int revents, void *arg)
2215	{	2397	{
2216	if (revents & EV_TIMEOUT)	2398	if (revents & EV_TIMEOUT)
2217	/* doh, nothing entered */;	2399	/* doh, nothing entered */;
2218	else if (revents & EV_READ)	2400	else if (revents & EV_READ)
2219	/* stdin might have data for us, joy! */;	2401	/* stdin might have data for us, joy! */;
2220	}	2402	}
2221		2403
2222	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2404	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2223		2405
2224	=item ev_feed_event (ev_loop *, watcher *, int revents)	2406	=item ev_feed_event (ev_loop *, watcher *, int revents)
2225		2407
2226	Feeds the given event set into the event loop, as if the specified event	2408	Feeds the given event set into the event loop, as if the specified event
2227	had happened for the specified watcher (which must be a pointer to an	2409	had happened for the specified watcher (which must be a pointer to an
…		…
2232	Feed an event on the given fd, as if a file descriptor backend detected	2414	Feed an event on the given fd, as if a file descriptor backend detected
2233	the given events it.	2415	the given events it.
2234		2416
2235	=item ev_feed_signal_event (ev_loop *loop, int signum)	2417	=item ev_feed_signal_event (ev_loop *loop, int signum)
2236		2418
2237	Feed an event as if the given signal occured (C<loop> must be the default	2419	Feed an event as if the given signal occurred (C<loop> must be the default
2238	loop!).	2420	loop!).
2239		2421
2240	=back	2422	=back
2241		2423
2242		2424
…		…
2258		2440
2259	=item * Priorities are not currently supported. Initialising priorities	2441	=item * Priorities are not currently supported. Initialising priorities
2260	will fail and all watchers will have the same priority, even though there	2442	will fail and all watchers will have the same priority, even though there
2261	is an ev_pri field.	2443	is an ev_pri field.
2262		2444
		2445	=item * In libevent, the last base created gets the signals, in libev, the
		2446	first base created (== the default loop) gets the signals.
		2447
2263	=item * Other members are not supported.	2448	=item * Other members are not supported.
2264		2449
2265	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2450	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2266	to use the libev header file and library.	2451	to use the libev header file and library.
2267		2452
2268	=back	2453	=back
2269		2454
2270	=head1 C++ SUPPORT	2455	=head1 C++ SUPPORT
2271		2456
2272	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2457	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2273	you to use some convinience methods to start/stop watchers and also change	2458	you to use some convenience methods to start/stop watchers and also change
2274	the callback model to a model using method callbacks on objects.	2459	the callback model to a model using method callbacks on objects.
2275		2460
2276	To use it,	2461	To use it,
2277		2462
2278	#include <ev++.h>	2463	#include <ev++.h>
2279		2464
2280	This automatically includes F<ev.h> and puts all of its definitions (many	2465	This automatically includes F<ev.h> and puts all of its definitions (many
2281	of them macros) into the global namespace. All C++ specific things are	2466	of them macros) into the global namespace. All C++ specific things are
2282	put into the C<ev> namespace. It should support all the same embedding	2467	put into the C<ev> namespace. It should support all the same embedding
2283	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2468	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2350	your compiler is good :), then the method will be fully inlined into the	2535	your compiler is good :), then the method will be fully inlined into the
2351	thunking function, making it as fast as a direct C callback.	2536	thunking function, making it as fast as a direct C callback.
2352		2537
2353	Example: simple class declaration and watcher initialisation	2538	Example: simple class declaration and watcher initialisation
2354		2539
2355	struct myclass	2540	struct myclass
2356	{	2541	{
2357	void io_cb (ev::io &w, int revents) { }	2542	void io_cb (ev::io &w, int revents) { }
2358	}	2543	}
2359		2544
2360	myclass obj;	2545	myclass obj;
2361	ev::io iow;	2546	ev::io iow;
2362	iow.set <myclass, &myclass::io_cb> (&obj);	2547	iow.set <myclass, &myclass::io_cb> (&obj);
2363		2548
2364	=item w->set<function> (void *data = 0)	2549	=item w->set<function> (void *data = 0)
2365		2550
2366	Also sets a callback, but uses a static method or plain function as	2551	Also sets a callback, but uses a static method or plain function as
2367	callback. The optional C<data> argument will be stored in the watcher's	2552	callback. The optional C<data> argument will be stored in the watcher's
…		…
2371		2556
2372	See the method-C<set> above for more details.	2557	See the method-C<set> above for more details.
2373		2558
2374	Example:	2559	Example:
2375		2560
2376	static void io_cb (ev::io &w, int revents) { }	2561	static void io_cb (ev::io &w, int revents) { }
2377	iow.set <io_cb> ();	2562	iow.set <io_cb> ();
2378		2563
2379	=item w->set (struct ev_loop *)	2564	=item w->set (struct ev_loop *)
2380		2565
2381	Associates a different C<struct ev_loop> with this watcher. You can only	2566	Associates a different C<struct ev_loop> with this watcher. You can only
2382	do this when the watcher is inactive (and not pending either).	2567	do this when the watcher is inactive (and not pending either).
2383		2568
2384	=item w->set ([args])	2569	=item w->set ([arguments])
2385		2570
2386	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2571	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2387	called at least once. Unlike the C counterpart, an active watcher gets	2572	called at least once. Unlike the C counterpart, an active watcher gets
2388	automatically stopped and restarted when reconfiguring it with this	2573	automatically stopped and restarted when reconfiguring it with this
2389	method.	2574	method.
2390		2575
2391	=item w->start ()	2576	=item w->start ()
…		…
2415	=back	2600	=back
2416		2601
2417	Example: Define a class with an IO and idle watcher, start one of them in	2602	Example: Define a class with an IO and idle watcher, start one of them in
2418	the constructor.	2603	the constructor.
2419		2604
2420	class myclass	2605	class myclass
2421	{	2606	{
2422	ev::io io; void io_cb (ev::io &w, int revents);	2607	ev::io io; void io_cb (ev::io &w, int revents);
2423	ev:idle idle void idle_cb (ev::idle &w, int revents);	2608	ev:idle idle void idle_cb (ev::idle &w, int revents);
2424		2609
2425	myclass (int fd)	2610	myclass (int fd)
2426	{	2611	{
2427	io .set <myclass, &myclass::io_cb > (this);	2612	io .set <myclass, &myclass::io_cb > (this);
2428	idle.set <myclass, &myclass::idle_cb> (this);	2613	idle.set <myclass, &myclass::idle_cb> (this);
2429		2614
2430	io.start (fd, ev::READ);	2615	io.start (fd, ev::READ);
2431	}	2616	}
2432	};	2617	};
		2618
		2619
		2620	=head1 OTHER LANGUAGE BINDINGS
		2621
		2622	Libev does not offer other language bindings itself, but bindings for a
		2623	number of languages exist in the form of third-party packages. If you know
		2624	any interesting language binding in addition to the ones listed here, drop
		2625	me a note.
		2626
		2627	=over 4
		2628
		2629	=item Perl
		2630
		2631	The EV module implements the full libev API and is actually used to test
		2632	libev. EV is developed together with libev. Apart from the EV core module,
		2633	there are additional modules that implement libev-compatible interfaces
		2634	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
		2635	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
		2636
		2637	It can be found and installed via CPAN, its homepage is at
		2638	L<http://software.schmorp.de/pkg/EV>.
		2639
		2640	=item Python
		2641
		2642	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2643	seems to be quite complete and well-documented. Note, however, that the
		2644	patch they require for libev is outright dangerous as it breaks the ABI
		2645	for everybody else, and therefore, should never be applied in an installed
		2646	libev (if python requires an incompatible ABI then it needs to embed
		2647	libev).
		2648
		2649	=item Ruby
		2650
		2651	Tony Arcieri has written a ruby extension that offers access to a subset
		2652	of the libev API and adds file handle abstractions, asynchronous DNS and
		2653	more on top of it. It can be found via gem servers. Its homepage is at
		2654	L<http://rev.rubyforge.org/>.
		2655
		2656	=item D
		2657
		2658	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
		2659	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.
		2660
		2661	=back
2433		2662
2434		2663
2435	=head1 MACRO MAGIC	2664	=head1 MACRO MAGIC
2436		2665
2437	Libev can be compiled with a variety of options, the most fundamantal	2666	Libev can be compiled with a variety of options, the most fundamental
2438	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2667	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2439	functions and callbacks have an initial C<struct ev_loop *> argument.	2668	functions and callbacks have an initial C<struct ev_loop *> argument.
2440		2669
2441	To make it easier to write programs that cope with either variant, the	2670	To make it easier to write programs that cope with either variant, the
2442	following macros are defined:	2671	following macros are defined:
…		…
2447		2676
2448	This provides the loop I<argument> for functions, if one is required ("ev	2677	This provides the loop I<argument> for functions, if one is required ("ev
2449	loop argument"). The C<EV_A> form is used when this is the sole argument,	2678	loop argument"). The C<EV_A> form is used when this is the sole argument,
2450	C<EV_A_> is used when other arguments are following. Example:	2679	C<EV_A_> is used when other arguments are following. Example:
2451		2680
2452	ev_unref (EV_A);	2681	ev_unref (EV_A);
2453	ev_timer_add (EV_A_ watcher);	2682	ev_timer_add (EV_A_ watcher);
2454	ev_loop (EV_A_ 0);	2683	ev_loop (EV_A_ 0);
2455		2684
2456	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2685	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2457	which is often provided by the following macro.	2686	which is often provided by the following macro.
2458		2687
2459	=item C<EV_P>, C<EV_P_>	2688	=item C<EV_P>, C<EV_P_>
2460		2689
2461	This provides the loop I<parameter> for functions, if one is required ("ev	2690	This provides the loop I<parameter> for functions, if one is required ("ev
2462	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2691	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2463	C<EV_P_> is used when other parameters are following. Example:	2692	C<EV_P_> is used when other parameters are following. Example:
2464		2693
2465	// this is how ev_unref is being declared	2694	// this is how ev_unref is being declared
2466	static void ev_unref (EV_P);	2695	static void ev_unref (EV_P);
2467		2696
2468	// this is how you can declare your typical callback	2697	// this is how you can declare your typical callback
2469	static void cb (EV_P_ ev_timer *w, int revents)	2698	static void cb (EV_P_ ev_timer *w, int revents)
2470		2699
2471	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2700	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2472	suitable for use with C<EV_A>.	2701	suitable for use with C<EV_A>.
2473		2702
2474	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2703	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2475		2704
2476	Similar to the other two macros, this gives you the value of the default	2705	Similar to the other two macros, this gives you the value of the default
2477	loop, if multiple loops are supported ("ev loop default").	2706	loop, if multiple loops are supported ("ev loop default").
		2707
		2708	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2709
		2710	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2711	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2712	is undefined when the default loop has not been initialised by a previous
		2713	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2714
		2715	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2716	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2478		2717
2479	=back	2718	=back
2480		2719
2481	Example: Declare and initialise a check watcher, utilising the above	2720	Example: Declare and initialise a check watcher, utilising the above
2482	macros so it will work regardless of whether multiple loops are supported	2721	macros so it will work regardless of whether multiple loops are supported
2483	or not.	2722	or not.
2484		2723
2485	static void	2724	static void
2486	check_cb (EV_P_ ev_timer *w, int revents)	2725	check_cb (EV_P_ ev_timer *w, int revents)
2487	{	2726	{
2488	ev_check_stop (EV_A_ w);	2727	ev_check_stop (EV_A_ w);
2489	}	2728	}
2490		2729
2491	ev_check check;	2730	ev_check check;
2492	ev_check_init (&check, check_cb);	2731	ev_check_init (&check, check_cb);
2493	ev_check_start (EV_DEFAULT_ &check);	2732	ev_check_start (EV_DEFAULT_ &check);
2494	ev_loop (EV_DEFAULT_ 0);	2733	ev_loop (EV_DEFAULT_ 0);
2495		2734
2496	=head1 EMBEDDING	2735	=head1 EMBEDDING
2497		2736
2498	Libev can (and often is) directly embedded into host	2737	Libev can (and often is) directly embedded into host
2499	applications. Examples of applications that embed it include the Deliantra	2738	applications. Examples of applications that embed it include the Deliantra
…		…
2506	libev somewhere in your source tree).	2745	libev somewhere in your source tree).
2507		2746
2508	=head2 FILESETS	2747	=head2 FILESETS
2509		2748
2510	Depending on what features you need you need to include one or more sets of files	2749	Depending on what features you need you need to include one or more sets of files
2511	in your app.	2750	in your application.
2512		2751
2513	=head3 CORE EVENT LOOP	2752	=head3 CORE EVENT LOOP
2514		2753
2515	To include only the libev core (all the C<ev_*> functions), with manual	2754	To include only the libev core (all the C<ev_*> functions), with manual
2516	configuration (no autoconf):	2755	configuration (no autoconf):
2517		2756
2518	#define EV_STANDALONE 1	2757	#define EV_STANDALONE 1
2519	#include "ev.c"	2758	#include "ev.c"
2520		2759
2521	This will automatically include F<ev.h>, too, and should be done in a	2760	This will automatically include F<ev.h>, too, and should be done in a
2522	single C source file only to provide the function implementations. To use	2761	single C source file only to provide the function implementations. To use
2523	it, do the same for F<ev.h> in all files wishing to use this API (best	2762	it, do the same for F<ev.h> in all files wishing to use this API (best
2524	done by writing a wrapper around F<ev.h> that you can include instead and	2763	done by writing a wrapper around F<ev.h> that you can include instead and
2525	where you can put other configuration options):	2764	where you can put other configuration options):
2526		2765
2527	#define EV_STANDALONE 1	2766	#define EV_STANDALONE 1
2528	#include "ev.h"	2767	#include "ev.h"
2529		2768
2530	Both header files and implementation files can be compiled with a C++	2769	Both header files and implementation files can be compiled with a C++
2531	compiler (at least, thats a stated goal, and breakage will be treated	2770	compiler (at least, thats a stated goal, and breakage will be treated
2532	as a bug).	2771	as a bug).
2533		2772
2534	You need the following files in your source tree, or in a directory	2773	You need the following files in your source tree, or in a directory
2535	in your include path (e.g. in libev/ when using -Ilibev):	2774	in your include path (e.g. in libev/ when using -Ilibev):
2536		2775
2537	ev.h	2776	ev.h
2538	ev.c	2777	ev.c
2539	ev_vars.h	2778	ev_vars.h
2540	ev_wrap.h	2779	ev_wrap.h
2541		2780
2542	ev_win32.c required on win32 platforms only	2781	ev_win32.c required on win32 platforms only
2543		2782
2544	ev_select.c only when select backend is enabled (which is enabled by default)	2783	ev_select.c only when select backend is enabled (which is enabled by default)
2545	ev_poll.c only when poll backend is enabled (disabled by default)	2784	ev_poll.c only when poll backend is enabled (disabled by default)
2546	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2785	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2547	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2786	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2548	ev_port.c only when the solaris port backend is enabled (disabled by default)	2787	ev_port.c only when the solaris port backend is enabled (disabled by default)
2549		2788
2550	F<ev.c> includes the backend files directly when enabled, so you only need	2789	F<ev.c> includes the backend files directly when enabled, so you only need
2551	to compile this single file.	2790	to compile this single file.
2552		2791
2553	=head3 LIBEVENT COMPATIBILITY API	2792	=head3 LIBEVENT COMPATIBILITY API
2554		2793
2555	To include the libevent compatibility API, also include:	2794	To include the libevent compatibility API, also include:
2556		2795
2557	#include "event.c"	2796	#include "event.c"
2558		2797
2559	in the file including F<ev.c>, and:	2798	in the file including F<ev.c>, and:
2560		2799
2561	#include "event.h"	2800	#include "event.h"
2562		2801
2563	in the files that want to use the libevent API. This also includes F<ev.h>.	2802	in the files that want to use the libevent API. This also includes F<ev.h>.
2564		2803
2565	You need the following additional files for this:	2804	You need the following additional files for this:
2566		2805
2567	event.h	2806	event.h
2568	event.c	2807	event.c
2569		2808
2570	=head3 AUTOCONF SUPPORT	2809	=head3 AUTOCONF SUPPORT
2571		2810
2572	Instead of using C<EV_STANDALONE=1> and providing your config in	2811	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2573	whatever way you want, you can also C<m4_include([libev.m4])> in your	2812	whatever way you want, you can also C<m4_include([libev.m4])> in your
2574	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2813	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2575	include F<config.h> and configure itself accordingly.	2814	include F<config.h> and configure itself accordingly.
2576		2815
2577	For this of course you need the m4 file:	2816	For this of course you need the m4 file:
2578		2817
2579	libev.m4	2818	libev.m4
2580		2819
2581	=head2 PREPROCESSOR SYMBOLS/MACROS	2820	=head2 PREPROCESSOR SYMBOLS/MACROS
2582		2821
2583	Libev can be configured via a variety of preprocessor symbols you have to define	2822	Libev can be configured via a variety of preprocessor symbols you have to
2584	before including any of its files. The default is not to build for multiplicity	2823	define before including any of its files. The default in the absence of
2585	and only include the select backend.	2824	autoconf is noted for every option.
2586		2825
2587	=over 4	2826	=over 4
2588		2827
2589	=item EV_STANDALONE	2828	=item EV_STANDALONE
2590		2829
…		…
2595	F<event.h> that are not directly supported by the libev core alone.	2834	F<event.h> that are not directly supported by the libev core alone.
2596		2835
2597	=item EV_USE_MONOTONIC	2836	=item EV_USE_MONOTONIC
2598		2837
2599	If defined to be C<1>, libev will try to detect the availability of the	2838	If defined to be C<1>, libev will try to detect the availability of the
2600	monotonic clock option at both compiletime and runtime. Otherwise no use	2839	monotonic clock option at both compile time and runtime. Otherwise no use
2601	of the monotonic clock option will be attempted. If you enable this, you	2840	of the monotonic clock option will be attempted. If you enable this, you
2602	usually have to link against librt or something similar. Enabling it when	2841	usually have to link against librt or something similar. Enabling it when
2603	the functionality isn't available is safe, though, although you have	2842	the functionality isn't available is safe, though, although you have
2604	to make sure you link against any libraries where the C<clock_gettime>	2843	to make sure you link against any libraries where the C<clock_gettime>
2605	function is hiding in (often F<-lrt>).	2844	function is hiding in (often F<-lrt>).
2606		2845
2607	=item EV_USE_REALTIME	2846	=item EV_USE_REALTIME
2608		2847
2609	If defined to be C<1>, libev will try to detect the availability of the	2848	If defined to be C<1>, libev will try to detect the availability of the
2610	realtime clock option at compiletime (and assume its availability at	2849	real-time clock option at compile time (and assume its availability at
2611	runtime if successful). Otherwise no use of the realtime clock option will	2850	runtime if successful). Otherwise no use of the real-time clock option will
2612	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2851	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2613	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2852	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2614	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2853	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2615		2854
2616	=item EV_USE_NANOSLEEP	2855	=item EV_USE_NANOSLEEP
2617		2856
2618	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	2857	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
2619	and will use it for delays. Otherwise it will use C<select ()>.	2858	and will use it for delays. Otherwise it will use C<select ()>.
2620		2859
		2860	=item EV_USE_EVENTFD
		2861
		2862	If defined to be C<1>, then libev will assume that C<eventfd ()> is
		2863	available and will probe for kernel support at runtime. This will improve
		2864	C<ev_signal> and C<ev_async> performance and reduce resource consumption.
		2865	If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
		2866	2.7 or newer, otherwise disabled.
		2867
2621	=item EV_USE_SELECT	2868	=item EV_USE_SELECT
2622		2869
2623	If undefined or defined to be C<1>, libev will compile in support for the	2870	If undefined or defined to be C<1>, libev will compile in support for the
2624	C<select>(2) backend. No attempt at autodetection will be done: if no	2871	C<select>(2) backend. No attempt at auto-detection will be done: if no
2625	other method takes over, select will be it. Otherwise the select backend	2872	other method takes over, select will be it. Otherwise the select backend
2626	will not be compiled in.	2873	will not be compiled in.
2627		2874
2628	=item EV_SELECT_USE_FD_SET	2875	=item EV_SELECT_USE_FD_SET
2629		2876
2630	If defined to C<1>, then the select backend will use the system C<fd_set>	2877	If defined to C<1>, then the select backend will use the system C<fd_set>
2631	structure. This is useful if libev doesn't compile due to a missing	2878	structure. This is useful if libev doesn't compile due to a missing
2632	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2879	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2633	exotic systems. This usually limits the range of file descriptors to some	2880	exotic systems. This usually limits the range of file descriptors to some
2634	low limit such as 1024 or might have other limitations (winsocket only	2881	low limit such as 1024 or might have other limitations (winsocket only
2635	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2882	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2636	influence the size of the C<fd_set> used.	2883	influence the size of the C<fd_set> used.
2637		2884
…		…
2661		2908
2662	=item EV_USE_EPOLL	2909	=item EV_USE_EPOLL
2663		2910
2664	If defined to be C<1>, libev will compile in support for the Linux	2911	If defined to be C<1>, libev will compile in support for the Linux
2665	C<epoll>(7) backend. Its availability will be detected at runtime,	2912	C<epoll>(7) backend. Its availability will be detected at runtime,
2666	otherwise another method will be used as fallback. This is the	2913	otherwise another method will be used as fallback. This is the preferred
2667	preferred backend for GNU/Linux systems.	2914	backend for GNU/Linux systems. If undefined, it will be enabled if the
		2915	headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2668		2916
2669	=item EV_USE_KQUEUE	2917	=item EV_USE_KQUEUE
2670		2918
2671	If defined to be C<1>, libev will compile in support for the BSD style	2919	If defined to be C<1>, libev will compile in support for the BSD style
2672	C<kqueue>(2) backend. Its actual availability will be detected at runtime,	2920	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
…		…
2685	otherwise another method will be used as fallback. This is the preferred	2933	otherwise another method will be used as fallback. This is the preferred
2686	backend for Solaris 10 systems.	2934	backend for Solaris 10 systems.
2687		2935
2688	=item EV_USE_DEVPOLL	2936	=item EV_USE_DEVPOLL
2689		2937
2690	reserved for future expansion, works like the USE symbols above.	2938	Reserved for future expansion, works like the USE symbols above.
2691		2939
2692	=item EV_USE_INOTIFY	2940	=item EV_USE_INOTIFY
2693		2941
2694	If defined to be C<1>, libev will compile in support for the Linux inotify	2942	If defined to be C<1>, libev will compile in support for the Linux inotify
2695	interface to speed up C<ev_stat> watchers. Its actual availability will	2943	interface to speed up C<ev_stat> watchers. Its actual availability will
2696	be detected at runtime.	2944	be detected at runtime. If undefined, it will be enabled if the headers
		2945	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2697		2946
2698	=item EV_ATOMIC_T	2947	=item EV_ATOMIC_T
2699		2948
2700	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	2949	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
2701	access is atomic with respect to other threads or signal contexts. No such	2950	access is atomic with respect to other threads or signal contexts. No such
2702	type is easily found in the C language, so you can provide your own type	2951	type is easily found in the C language, so you can provide your own type
2703	that you know is safe for your purposes. It is used both for signal handler "locking"	2952	that you know is safe for your purposes. It is used both for signal handler "locking"
2704	as well as for signal and thread safety in C<ev_async> watchers.	2953	as well as for signal and thread safety in C<ev_async> watchers.
2705		2954
2706	In the absense of this define, libev will use C<sig_atomic_t volatile>	2955	In the absence of this define, libev will use C<sig_atomic_t volatile>
2707	(from F<signal.h>), which is usually good enough on most platforms.	2956	(from F<signal.h>), which is usually good enough on most platforms.
2708		2957
2709	=item EV_H	2958	=item EV_H
2710		2959
2711	The name of the F<ev.h> header file used to include it. The default if	2960	The name of the F<ev.h> header file used to include it. The default if
…		…
2750	When doing priority-based operations, libev usually has to linearly search	2999	When doing priority-based operations, libev usually has to linearly search
2751	all the priorities, so having many of them (hundreds) uses a lot of space	3000	all the priorities, so having many of them (hundreds) uses a lot of space
2752	and time, so using the defaults of five priorities (-2 .. +2) is usually	3001	and time, so using the defaults of five priorities (-2 .. +2) is usually
2753	fine.	3002	fine.
2754		3003
2755	If your embedding app does not need any priorities, defining these both to	3004	If your embedding application does not need any priorities, defining these both to
2756	C<0> will save some memory and cpu.	3005	C<0> will save some memory and CPU.
2757		3006
2758	=item EV_PERIODIC_ENABLE	3007	=item EV_PERIODIC_ENABLE
2759		3008
2760	If undefined or defined to be C<1>, then periodic timers are supported. If	3009	If undefined or defined to be C<1>, then periodic timers are supported. If
2761	defined to be C<0>, then they are not. Disabling them saves a few kB of	3010	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2788	defined to be C<0>, then they are not.	3037	defined to be C<0>, then they are not.
2789		3038
2790	=item EV_MINIMAL	3039	=item EV_MINIMAL
2791		3040
2792	If you need to shave off some kilobytes of code at the expense of some	3041	If you need to shave off some kilobytes of code at the expense of some
2793	speed, define this symbol to C<1>. Currently only used for gcc to override	3042	speed, define this symbol to C<1>. Currently this is used to override some
2794	some inlining decisions, saves roughly 30% codesize of amd64.	3043	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3044	much smaller 2-heap for timer management over the default 4-heap.
2795		3045
2796	=item EV_PID_HASHSIZE	3046	=item EV_PID_HASHSIZE
2797		3047
2798	C<ev_child> watchers use a small hash table to distribute workload by	3048	C<ev_child> watchers use a small hash table to distribute workload by
2799	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3049	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2806	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3056	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2807	usually more than enough. If you need to manage thousands of C<ev_stat>	3057	usually more than enough. If you need to manage thousands of C<ev_stat>
2808	watchers you might want to increase this value (I<must> be a power of	3058	watchers you might want to increase this value (I<must> be a power of
2809	two).	3059	two).
2810		3060
		3061	=item EV_USE_4HEAP
		3062
		3063	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3064	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3065	to C<1>. The 4-heap uses more complicated (longer) code but has
		3066	noticeably faster performance with many (thousands) of watchers.
		3067
		3068	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3069	(disabled).
		3070
		3071	=item EV_HEAP_CACHE_AT
		3072
		3073	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3074	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3075	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3076	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3077	but avoids random read accesses on heap changes. This improves performance
		3078	noticeably with with many (hundreds) of watchers.
		3079
		3080	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3081	(disabled).
		3082
		3083	=item EV_VERIFY
		3084
		3085	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3086	be done: If set to C<0>, no internal verification code will be compiled
		3087	in. If set to C<1>, then verification code will be compiled in, but not
		3088	called. If set to C<2>, then the internal verification code will be
		3089	called once per loop, which can slow down libev. If set to C<3>, then the
		3090	verification code will be called very frequently, which will slow down
		3091	libev considerably.
		3092
		3093	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3094	C<0.>
		3095
2811	=item EV_COMMON	3096	=item EV_COMMON
2812		3097
2813	By default, all watchers have a C<void *data> member. By redefining	3098	By default, all watchers have a C<void *data> member. By redefining
2814	this macro to a something else you can include more and other types of	3099	this macro to a something else you can include more and other types of
2815	members. You have to define it each time you include one of the files,	3100	members. You have to define it each time you include one of the files,
2816	though, and it must be identical each time.	3101	though, and it must be identical each time.
2817		3102
2818	For example, the perl EV module uses something like this:	3103	For example, the perl EV module uses something like this:
2819		3104
2820	#define EV_COMMON \	3105	#define EV_COMMON \
2821	SV *self; /* contains this struct */ \	3106	SV *self; /* contains this struct */ \
2822	SV *cb_sv, *fh /* note no trailing ";" */	3107	SV *cb_sv, *fh /* note no trailing ";" */
2823		3108
2824	=item EV_CB_DECLARE (type)	3109	=item EV_CB_DECLARE (type)
2825		3110
2826	=item EV_CB_INVOKE (watcher, revents)	3111	=item EV_CB_INVOKE (watcher, revents)
2827		3112
…		…
2834	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3119	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2835	method calls instead of plain function calls in C++.	3120	method calls instead of plain function calls in C++.
2836		3121
2837	=head2 EXPORTED API SYMBOLS	3122	=head2 EXPORTED API SYMBOLS
2838		3123
2839	If you need to re-export the API (e.g. via a dll) and you need a list of	3124	If you need to re-export the API (e.g. via a DLL) and you need a list of
2840	exported symbols, you can use the provided F<Symbol.*> files which list	3125	exported symbols, you can use the provided F<Symbol.*> files which list
2841	all public symbols, one per line:	3126	all public symbols, one per line:
2842		3127
2843	Symbols.ev for libev proper	3128	Symbols.ev for libev proper
2844	Symbols.event for the libevent emulation	3129	Symbols.event for the libevent emulation
2845		3130
2846	This can also be used to rename all public symbols to avoid clashes with	3131	This can also be used to rename all public symbols to avoid clashes with
2847	multiple versions of libev linked together (which is obviously bad in	3132	multiple versions of libev linked together (which is obviously bad in
2848	itself, but sometimes it is inconvinient to avoid this).	3133	itself, but sometimes it is inconvenient to avoid this).
2849		3134
2850	A sed command like this will create wrapper C<#define>'s that you need to	3135	A sed command like this will create wrapper C<#define>'s that you need to
2851	include before including F<ev.h>:	3136	include before including F<ev.h>:
2852		3137
2853	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3138	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
2870	file.	3155	file.
2871		3156
2872	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3157	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2873	that everybody includes and which overrides some configure choices:	3158	that everybody includes and which overrides some configure choices:
2874		3159
2875	#define EV_MINIMAL 1	3160	#define EV_MINIMAL 1
2876	#define EV_USE_POLL 0	3161	#define EV_USE_POLL 0
2877	#define EV_MULTIPLICITY 0	3162	#define EV_MULTIPLICITY 0
2878	#define EV_PERIODIC_ENABLE 0	3163	#define EV_PERIODIC_ENABLE 0
2879	#define EV_STAT_ENABLE 0	3164	#define EV_STAT_ENABLE 0
2880	#define EV_FORK_ENABLE 0	3165	#define EV_FORK_ENABLE 0
2881	#define EV_CONFIG_H <config.h>	3166	#define EV_CONFIG_H <config.h>
2882	#define EV_MINPRI 0	3167	#define EV_MINPRI 0
2883	#define EV_MAXPRI 0	3168	#define EV_MAXPRI 0
2884		3169
2885	#include "ev++.h"	3170	#include "ev++.h"
2886		3171
2887	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3172	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2888		3173
2889	#include "ev_cpp.h"	3174	#include "ev_cpp.h"
2890	#include "ev.c"	3175	#include "ev.c"
		3176
		3177
		3178	=head1 THREADS AND COROUTINES
		3179
		3180	=head2 THREADS
		3181
		3182	Libev itself is completely thread-safe, but it uses no locking. This
		3183	means that you can use as many loops as you want in parallel, as long as
		3184	only one thread ever calls into one libev function with the same loop
		3185	parameter.
		3186
		3187	Or put differently: calls with different loop parameters can be done in
		3188	parallel from multiple threads, calls with the same loop parameter must be
		3189	done serially (but can be done from different threads, as long as only one
		3190	thread ever is inside a call at any point in time, e.g. by using a mutex
		3191	per loop).
		3192
		3193	If you want to know which design is best for your problem, then I cannot
		3194	help you but by giving some generic advice:
		3195
		3196	=over 4
		3197
		3198	=item * most applications have a main thread: use the default libev loop
		3199	in that thread, or create a separate thread running only the default loop.
		3200
		3201	This helps integrating other libraries or software modules that use libev
		3202	themselves and don't care/know about threading.
		3203
		3204	=item * one loop per thread is usually a good model.
		3205
		3206	Doing this is almost never wrong, sometimes a better-performance model
		3207	exists, but it is always a good start.
		3208
		3209	=item * other models exist, such as the leader/follower pattern, where one
		3210	loop is handed through multiple threads in a kind of round-robin fashion.
		3211
		3212	Choosing a model is hard - look around, learn, know that usually you can do
		3213	better than you currently do :-)
		3214
		3215	=item * often you need to talk to some other thread which blocks in the
		3216	event loop - C<ev_async> watchers can be used to wake them up from other
		3217	threads safely (or from signal contexts...).
		3218
		3219	=back
		3220
		3221	=head2 COROUTINES
		3222
		3223	Libev is much more accommodating to coroutines ("cooperative threads"):
		3224	libev fully supports nesting calls to it's functions from different
		3225	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3226	different coroutines and switch freely between both coroutines running the
		3227	loop, as long as you don't confuse yourself). The only exception is that
		3228	you must not do this from C<ev_periodic> reschedule callbacks.
		3229
		3230	Care has been invested into making sure that libev does not keep local
		3231	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3232	switches.
2891		3233
2892		3234
2893	=head1 COMPLEXITIES	3235	=head1 COMPLEXITIES
2894		3236
2895	In this section the complexities of (many of) the algorithms used inside	3237	In this section the complexities of (many of) the algorithms used inside
…		…
2927	correct watcher to remove. The lists are usually short (you don't usually	3269	correct watcher to remove. The lists are usually short (you don't usually
2928	have many watchers waiting for the same fd or signal).	3270	have many watchers waiting for the same fd or signal).
2929		3271
2930	=item Finding the next timer in each loop iteration: O(1)	3272	=item Finding the next timer in each loop iteration: O(1)
2931		3273
2932	By virtue of using a binary heap, the next timer is always found at the	3274	By virtue of using a binary or 4-heap, the next timer is always found at a
2933	beginning of the storage array.	3275	fixed position in the storage array.
2934		3276
2935	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3277	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2936		3278
2937	A change means an I/O watcher gets started or stopped, which requires	3279	A change means an I/O watcher gets started or stopped, which requires
2938	libev to recalculate its status (and possibly tell the kernel, depending	3280	libev to recalculate its status (and possibly tell the kernel, depending
2939	on backend and wether C<ev_io_set> was used).	3281	on backend and whether C<ev_io_set> was used).
2940		3282
2941	=item Activating one watcher (putting it into the pending state): O(1)	3283	=item Activating one watcher (putting it into the pending state): O(1)
2942		3284
2943	=item Priority handling: O(number_of_priorities)	3285	=item Priority handling: O(number_of_priorities)
2944		3286
…		…
2951		3293
2952	=item Processing ev_async_send: O(number_of_async_watchers)	3294	=item Processing ev_async_send: O(number_of_async_watchers)
2953		3295
2954	=item Processing signals: O(max_signal_number)	3296	=item Processing signals: O(max_signal_number)
2955		3297
2956	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3298	Sending involves a system call I<iff> there were no other C<ev_async_send>
2957	calls in the current loop iteration. Checking for async and signal events	3299	calls in the current loop iteration. Checking for async and signal events
2958	involves iterating over all running async watchers or all signal numbers.	3300	involves iterating over all running async watchers or all signal numbers.
2959		3301
2960	=back	3302	=back
2961		3303
2962		3304
2963	=head1 Win32 platform limitations and workarounds	3305	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
2964		3306
2965	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3307	Win32 doesn't support any of the standards (e.g. POSIX) that libev
2966	requires, and its I/O model is fundamentally incompatible with the POSIX	3308	requires, and its I/O model is fundamentally incompatible with the POSIX
2967	model. Libev still offers limited functionality on this platform in	3309	model. Libev still offers limited functionality on this platform in
2968	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3310	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
2969	descriptors. This only applies when using Win32 natively, not when using	3311	descriptors. This only applies when using Win32 natively, not when using
2970	e.g. cygwin.	3312	e.g. cygwin.
2971		3313
		3314	Lifting these limitations would basically require the full
		3315	re-implementation of the I/O system. If you are into these kinds of
		3316	things, then note that glib does exactly that for you in a very portable
		3317	way (note also that glib is the slowest event library known to man).
		3318
2972	There is no supported compilation method available on windows except	3319	There is no supported compilation method available on windows except
2973	embedding it into other applications.	3320	embedding it into other applications.
2974		3321
		3322	Not a libev limitation but worth mentioning: windows apparently doesn't
		3323	accept large writes: instead of resulting in a partial write, windows will
		3324	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3325	so make sure you only write small amounts into your sockets (less than a
		3326	megabyte seems safe, but thsi apparently depends on the amount of memory
		3327	available).
		3328
2975	Due to the many, low, and arbitrary limits on the win32 platform and the	3329	Due to the many, low, and arbitrary limits on the win32 platform and
2976	abysmal performance of winsockets, using a large number of sockets is not	3330	the abysmal performance of winsockets, using a large number of sockets
2977	recommended (and not reasonable). If your program needs to use more than	3331	is not recommended (and not reasonable). If your program needs to use
2978	a hundred or so sockets, then likely it needs to use a totally different	3332	more than a hundred or so sockets, then likely it needs to use a totally
2979	implementation for windows, as libev offers the POSIX model, which cannot	3333	different implementation for windows, as libev offers the POSIX readiness
2980	be implemented efficiently on windows (microsoft monopoly games).	3334	notification model, which cannot be implemented efficiently on windows
		3335	(Microsoft monopoly games).
		3336
		3337	A typical way to use libev under windows is to embed it (see the embedding
		3338	section for details) and use the following F<evwrap.h> header file instead
		3339	of F<ev.h>:
		3340
		3341	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3342	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3343
		3344	#include "ev.h"
		3345
		3346	And compile the following F<evwrap.c> file into your project (make sure
		3347	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3348
		3349	#include "evwrap.h"
		3350	#include "ev.c"
2981		3351
2982	=over 4	3352	=over 4
2983		3353
2984	=item The winsocket select function	3354	=item The winsocket select function
2985		3355
2986	The winsocket C<select> function doesn't follow POSIX in that it requires	3356	The winsocket C<select> function doesn't follow POSIX in that it
2987	socket I<handles> and not socket I<file descriptors>. This makes select	3357	requires socket I<handles> and not socket I<file descriptors> (it is
2988	very inefficient, and also requires a mapping from file descriptors	3358	also extremely buggy). This makes select very inefficient, and also
2989	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3359	requires a mapping from file descriptors to socket handles (the Microsoft
2990	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3360	C runtime provides the function C<_open_osfhandle> for this). See the
2991	symbols for more info.	3361	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3362	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
2992		3363
2993	The configuration for a "naked" win32 using the microsoft runtime	3364	The configuration for a "naked" win32 using the Microsoft runtime
2994	libraries and raw winsocket select is:	3365	libraries and raw winsocket select is:
2995		3366
2996	#define EV_USE_SELECT 1	3367	#define EV_USE_SELECT 1
2997	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3368	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
2998		3369
2999	Note that winsockets handling of fd sets is O(n), so you can easily get a	3370	Note that winsockets handling of fd sets is O(n), so you can easily get a
3000	complexity in the O(n²) range when using win32.	3371	complexity in the O(n²) range when using win32.
3001		3372
3002	=item Limited number of file descriptors	3373	=item Limited number of file descriptors
3003		3374
3004	Windows has numerous arbitrary (and low) limits on things. Early versions	3375	Windows has numerous arbitrary (and low) limits on things.
3005	of winsocket's select only supported waiting for a max. of C<64> handles	3376
		3377	Early versions of winsocket's select only supported waiting for a maximum
3006	(probably owning to the fact that all windows kernels can only wait for	3378	of C<64> handles (probably owning to the fact that all windows kernels
3007	C<64> things at the same time internally; microsoft recommends spawning a	3379	can only wait for C<64> things at the same time internally; Microsoft
3008	chain of threads and wait for 63 handles and the previous thread in each).	3380	recommends spawning a chain of threads and wait for 63 handles and the
		3381	previous thread in each. Great).
3009		3382
3010	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3383	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3011	to some high number (e.g. C<2048>) before compiling the winsocket select	3384	to some high number (e.g. C<2048>) before compiling the winsocket select
3012	call (which might be in libev or elsewhere, for example, perl does its own	3385	call (which might be in libev or elsewhere, for example, perl does its own
3013	select emulation on windows).	3386	select emulation on windows).
3014		3387
3015	Another limit is the number of file descriptors in the microsoft runtime	3388	Another limit is the number of file descriptors in the Microsoft runtime
3016	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3389	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3017	or something like this inside microsoft). You can increase this by calling	3390	or something like this inside Microsoft). You can increase this by calling
3018	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3391	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3019	arbitrary limit), but is broken in many versions of the microsoft runtime	3392	arbitrary limit), but is broken in many versions of the Microsoft runtime
3020	libraries.	3393	libraries.
3021		3394
3022	This might get you to about C<512> or C<2048> sockets (depending on	3395	This might get you to about C<512> or C<2048> sockets (depending on
3023	windows version and/or the phase of the moon). To get more, you need to	3396	windows version and/or the phase of the moon). To get more, you need to
3024	wrap all I/O functions and provide your own fd management, but the cost of	3397	wrap all I/O functions and provide your own fd management, but the cost of
3025	calling select (O(n²)) will likely make this unworkable.	3398	calling select (O(n²)) will likely make this unworkable.
3026		3399
3027	=back	3400	=back
3028		3401
3029		3402
		3403	=head1 PORTABILITY REQUIREMENTS
		3404
		3405	In addition to a working ISO-C implementation, libev relies on a few
		3406	additional extensions:
		3407
		3408	=over 4
		3409
		3410	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3411	calling conventions regardless of C<ev_watcher_type *>.
		3412
		3413	Libev assumes not only that all watcher pointers have the same internal
		3414	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3415	assumes that the same (machine) code can be used to call any watcher
		3416	callback: The watcher callbacks have different type signatures, but libev
		3417	calls them using an C<ev_watcher *> internally.
		3418
		3419	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3420
		3421	The type C<sig_atomic_t volatile> (or whatever is defined as
		3422	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3423	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3424	believed to be sufficiently portable.
		3425
		3426	=item C<sigprocmask> must work in a threaded environment
		3427
		3428	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3429	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3430	pthread implementations will either allow C<sigprocmask> in the "main
		3431	thread" or will block signals process-wide, both behaviours would
		3432	be compatible with libev. Interaction between C<sigprocmask> and
		3433	C<pthread_sigmask> could complicate things, however.
		3434
		3435	The most portable way to handle signals is to block signals in all threads
		3436	except the initial one, and run the default loop in the initial thread as
		3437	well.
		3438
		3439	=item C<long> must be large enough for common memory allocation sizes
		3440
		3441	To improve portability and simplify using libev, libev uses C<long>
		3442	internally instead of C<size_t> when allocating its data structures. On
		3443	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3444	is still at least 31 bits everywhere, which is enough for hundreds of
		3445	millions of watchers.
		3446
		3447	=item C<double> must hold a time value in seconds with enough accuracy
		3448
		3449	The type C<double> is used to represent timestamps. It is required to
		3450	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3451	enough for at least into the year 4000. This requirement is fulfilled by
		3452	implementations implementing IEEE 754 (basically all existing ones).
		3453
		3454	=back
		3455
		3456	If you know of other additional requirements drop me a note.
		3457
		3458
		3459	=head1 COMPILER WARNINGS
		3460
		3461	Depending on your compiler and compiler settings, you might get no or a
		3462	lot of warnings when compiling libev code. Some people are apparently
		3463	scared by this.
		3464
		3465	However, these are unavoidable for many reasons. For one, each compiler
		3466	has different warnings, and each user has different tastes regarding
		3467	warning options. "Warn-free" code therefore cannot be a goal except when
		3468	targeting a specific compiler and compiler-version.
		3469
		3470	Another reason is that some compiler warnings require elaborate
		3471	workarounds, or other changes to the code that make it less clear and less
		3472	maintainable.
		3473
		3474	And of course, some compiler warnings are just plain stupid, or simply
		3475	wrong (because they don't actually warn about the condition their message
		3476	seems to warn about).
		3477
		3478	While libev is written to generate as few warnings as possible,
		3479	"warn-free" code is not a goal, and it is recommended not to build libev
		3480	with any compiler warnings enabled unless you are prepared to cope with
		3481	them (e.g. by ignoring them). Remember that warnings are just that:
		3482	warnings, not errors, or proof of bugs.
		3483
		3484
		3485	=head1 VALGRIND
		3486
		3487	Valgrind has a special section here because it is a popular tool that is
		3488	highly useful, but valgrind reports are very hard to interpret.
		3489
		3490	If you think you found a bug (memory leak, uninitialised data access etc.)
		3491	in libev, then check twice: If valgrind reports something like:
		3492
		3493	==2274== definitely lost: 0 bytes in 0 blocks.
		3494	==2274== possibly lost: 0 bytes in 0 blocks.
		3495	==2274== still reachable: 256 bytes in 1 blocks.
		3496
		3497	Then there is no memory leak. Similarly, under some circumstances,
		3498	valgrind might report kernel bugs as if it were a bug in libev, or it
		3499	might be confused (it is a very good tool, but only a tool).
		3500
		3501	If you are unsure about something, feel free to contact the mailing list
		3502	with the full valgrind report and an explanation on why you think this is
		3503	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3504	no bug" answer and take the chance of learning how to interpret valgrind
		3505	properly.
		3506
		3507	If you need, for some reason, empty reports from valgrind for your project
		3508	I suggest using suppression lists.
		3509
		3510
3030	=head1 AUTHOR	3511	=head1 AUTHOR
3031		3512
3032	Marc Lehmann <libev@schmorp.de>.	3513	Marc Lehmann <libev@schmorp.de>.
3033		3514

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