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Revision 1.134 by root, Sat Mar 8 07:04:56 2008 UTC vs.
Revision 1.172 by root, Wed Aug 6 07:01:25 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
…		…
553	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
554	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
555	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.
556		596
557	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
558	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
559	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
560	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
561	external event in conjunction with something not expressible using other	601	external event in conjunction with something not expressible using other
562	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
563	usually a better approach for this kind of thing.	603	usually a better approach for this kind of thing.
564		604
565	Here are the gory details of what C<ev_loop> does:	605	Here are the gory details of what C<ev_loop> does:
566		606
567	- Before the first iteration, call any pending watchers.	607	- Before the first iteration, call any pending watchers.
568	* If EVFLAG_FORKCHECK was used, check for a fork.	608	* If EVFLAG_FORKCHECK was used, check for a fork.
569	- If a fork was detected, queue and call all fork watchers.	609	- If a fork was detected (by any means), queue and call all fork watchers.
570	- Queue and call all prepare watchers.	610	- Queue and call all prepare watchers.
571	- If we have been forked, recreate the kernel state.	611	- If we have been forked, detach and recreate the kernel state
		612	as to not disturb the other process.
572	- Update the kernel state with all outstanding changes.	613	- Update the kernel state with all outstanding changes.
573	- Update the "event loop time".	614	- Update the "event loop time" (ev_now ()).
574	- Calculate for how long to sleep or block, if at all	615	- Calculate for how long to sleep or block, if at all
575	(active idle watchers, EVLOOP_NONBLOCK or not having	616	(active idle watchers, EVLOOP_NONBLOCK or not having
576	any active watchers at all will result in not sleeping).	617	any active watchers at all will result in not sleeping).
577	- Sleep if the I/O and timer collect interval say so.	618	- Sleep if the I/O and timer collect interval say so.
578	- Block the process, waiting for any events.	619	- Block the process, waiting for any events.
579	- Queue all outstanding I/O (fd) events.	620	- Queue all outstanding I/O (fd) events.
580	- Update the "event loop time" and do time jump handling.	621	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
581	- Queue all outstanding timers.	622	- Queue all outstanding timers.
582	- Queue all outstanding periodics.	623	- Queue all outstanding periodics.
583	- If no events are pending now, queue all idle watchers.	624	- Unless any events are pending now, queue all idle watchers.
584	- Queue all check watchers.	625	- Queue all check watchers.
585	- Call all queued watchers in reverse order (i.e. check watchers first).	626	- Call all queued watchers in reverse order (i.e. check watchers first).
586	Signals and child watchers are implemented as I/O watchers, and will	627	Signals and child watchers are implemented as I/O watchers, and will
587	be handled here by queueing them when their watcher gets executed.	628	be handled here by queueing them when their watcher gets executed.
588	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	629	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
…		…
593	anymore.	634	anymore.
594		635
595	... queue jobs here, make sure they register event watchers as long	636	... queue jobs here, make sure they register event watchers as long
596	... as they still have work to do (even an idle watcher will do..)	637	... as they still have work to do (even an idle watcher will do..)
597	ev_loop (my_loop, 0);	638	ev_loop (my_loop, 0);
598	... jobs done. yeah!	639	... jobs done or somebody called unloop. yeah!
599		640
600	=item ev_unloop (loop, how)	641	=item ev_unloop (loop, how)
601		642
602	Can be used to make a call to C<ev_loop> return early (but only after it	643	Can be used to make a call to C<ev_loop> return early (but only after it
603	has processed all outstanding events). The C<how> argument must be either	644	has processed all outstanding events). The C<how> argument must be either
…		…
624	respectively).	665	respectively).
625		666
626	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	667	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
627	running when nothing else is active.	668	running when nothing else is active.
628		669
629	struct ev_signal exitsig;	670	struct ev_signal exitsig;
630	ev_signal_init (&exitsig, sig_cb, SIGINT);	671	ev_signal_init (&exitsig, sig_cb, SIGINT);
631	ev_signal_start (loop, &exitsig);	672	ev_signal_start (loop, &exitsig);
632	evf_unref (loop);	673	evf_unref (loop);
633		674
634	Example: For some weird reason, unregister the above signal handler again.	675	Example: For some weird reason, unregister the above signal handler again.
635		676
636	ev_ref (loop);	677	ev_ref (loop);
637	ev_signal_stop (loop, &exitsig);	678	ev_signal_stop (loop, &exitsig);
638		679
639	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	680	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
640		681
641	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	682	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
642		683
643	These advanced functions influence the time that libev will spend waiting	684	These advanced functions influence the time that libev will spend waiting
644	for events. Both are by default C<0>, meaning that libev will try to	685	for events. Both time intervals are by default C<0>, meaning that libev
645	invoke timer/periodic callbacks and I/O callbacks with minimum latency.	686	will try to invoke timer/periodic callbacks and I/O callbacks with minimum
		687	latency.
646		688
647	Setting these to a higher value (the C<interval> I<must> be >= C<0>)	689	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
648	allows libev to delay invocation of I/O and timer/periodic callbacks to	690	allows libev to delay invocation of I/O and timer/periodic callbacks
649	increase efficiency of loop iterations.	691	to increase efficiency of loop iterations (or to increase power-saving
		692	opportunities).
650		693
651	The background is that sometimes your program runs just fast enough to	694	The background is that sometimes your program runs just fast enough to
652	handle one (or very few) event(s) per loop iteration. While this makes	695	handle one (or very few) event(s) per loop iteration. While this makes
653	the program responsive, it also wastes a lot of CPU time to poll for new	696	the program responsive, it also wastes a lot of CPU time to poll for new
654	events, especially with backends like C<select ()> which have a high	697	events, especially with backends like C<select ()> which have a high
…		…
664	to spend more time collecting timeouts, at the expense of increased	707	to spend more time collecting timeouts, at the expense of increased
665	latency (the watcher callback will be called later). C<ev_io> watchers	708	latency (the watcher callback will be called later). C<ev_io> watchers
666	will not be affected. Setting this to a non-null value will not introduce	709	will not be affected. Setting this to a non-null value will not introduce
667	any overhead in libev.	710	any overhead in libev.
668		711
669	Many (busy) programs can usually benefit by setting the io collect	712	Many (busy) programs can usually benefit by setting the I/O collect
670	interval to a value near C<0.1> or so, which is often enough for	713	interval to a value near C<0.1> or so, which is often enough for
671	interactive servers (of course not for games), likewise for timeouts. It	714	interactive servers (of course not for games), likewise for timeouts. It
672	usually doesn't make much sense to set it to a lower value than C<0.01>,	715	usually doesn't make much sense to set it to a lower value than C<0.01>,
673	as this approsaches the timing granularity of most systems.	716	as this approaches the timing granularity of most systems.
		717
		718	Setting the I<timeout collect interval> can improve the opportunity for
		719	saving power, as the program will "bundle" timer callback invocations that
		720	are "near" in time together, by delaying some, thus reducing the number of
		721	times the process sleeps and wakes up again. Another useful technique to
		722	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
		723	they fire on, say, one-second boundaries only.
		724
		725	=item ev_loop_verify (loop)
		726
		727	This function only does something when C<EV_VERIFY> support has been
		728	compiled in. It tries to go through all internal structures and checks
		729	them for validity. If anything is found to be inconsistent, it will print
		730	an error message to standard error and call C<abort ()>.
		731
		732	This can be used to catch bugs inside libev itself: under normal
		733	circumstances, this function will never abort as of course libev keeps its
		734	data structures consistent.
674		735
675	=back	736	=back
676		737
677		738
678	=head1 ANATOMY OF A WATCHER	739	=head1 ANATOMY OF A WATCHER
679		740
680	A watcher is a structure that you create and register to record your	741	A watcher is a structure that you create and register to record your
681	interest in some event. For instance, if you want to wait for STDIN to	742	interest in some event. For instance, if you want to wait for STDIN to
682	become readable, you would create an C<ev_io> watcher for that:	743	become readable, you would create an C<ev_io> watcher for that:
683		744
684	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	745	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
685	{	746	{
686	ev_io_stop (w);	747	ev_io_stop (w);
687	ev_unloop (loop, EVUNLOOP_ALL);	748	ev_unloop (loop, EVUNLOOP_ALL);
688	}	749	}
689		750
690	struct ev_loop *loop = ev_default_loop (0);	751	struct ev_loop *loop = ev_default_loop (0);
691	struct ev_io stdin_watcher;	752	struct ev_io stdin_watcher;
692	ev_init (&stdin_watcher, my_cb);	753	ev_init (&stdin_watcher, my_cb);
693	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	754	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
694	ev_io_start (loop, &stdin_watcher);	755	ev_io_start (loop, &stdin_watcher);
695	ev_loop (loop, 0);	756	ev_loop (loop, 0);
696		757
697	As you can see, you are responsible for allocating the memory for your	758	As you can see, you are responsible for allocating the memory for your
698	watcher structures (and it is usually a bad idea to do this on the stack,	759	watcher structures (and it is usually a bad idea to do this on the stack,
699	although this can sometimes be quite valid).	760	although this can sometimes be quite valid).
700		761
701	Each watcher structure must be initialised by a call to C<ev_init	762	Each watcher structure must be initialised by a call to C<ev_init
702	(watcher *, callback)>, which expects a callback to be provided. This	763	(watcher *, callback)>, which expects a callback to be provided. This
703	callback gets invoked each time the event occurs (or, in the case of io	764	callback gets invoked each time the event occurs (or, in the case of I/O
704	watchers, each time the event loop detects that the file descriptor given	765	watchers, each time the event loop detects that the file descriptor given
705	is readable and/or writable).	766	is readable and/or writable).
706		767
707	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	768	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
708	with arguments specific to this watcher type. There is also a macro	769	with arguments specific to this watcher type. There is also a macro
…		…
784		845
785	The given async watcher has been asynchronously notified (see C<ev_async>).	846	The given async watcher has been asynchronously notified (see C<ev_async>).
786		847
787	=item C<EV_ERROR>	848	=item C<EV_ERROR>
788		849
789	An unspecified error has occured, the watcher has been stopped. This might	850	An unspecified error has occurred, the watcher has been stopped. This might
790	happen because the watcher could not be properly started because libev	851	happen because the watcher could not be properly started because libev
791	ran out of memory, a file descriptor was found to be closed or any other	852	ran out of memory, a file descriptor was found to be closed or any other
792	problem. You best act on it by reporting the problem and somehow coping	853	problem. You best act on it by reporting the problem and somehow coping
793	with the watcher being stopped.	854	with the watcher being stopped.
794		855
795	Libev will usually signal a few "dummy" events together with an error,	856	Libev will usually signal a few "dummy" events together with an error,
796	for example it might indicate that a fd is readable or writable, and if	857	for example it might indicate that a fd is readable or writable, and if
797	your callbacks is well-written it can just attempt the operation and cope	858	your callbacks is well-written it can just attempt the operation and cope
798	with the error from read() or write(). This will not work in multithreaded	859	with the error from read() or write(). This will not work in multi-threaded
799	programs, though, so beware.	860	programs, though, so beware.
800		861
801	=back	862	=back
802		863
803	=head2 GENERIC WATCHER FUNCTIONS	864	=head2 GENERIC WATCHER FUNCTIONS
…		…
833	Although some watcher types do not have type-specific arguments	894	Although some watcher types do not have type-specific arguments
834	(e.g. C<ev_prepare>) you still need to call its C<set> macro.	895	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
835		896
836	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	897	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
837		898
838	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	899	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
839	calls into a single call. This is the most convinient method to initialise	900	calls into a single call. This is the most convenient method to initialise
840	a watcher. The same limitations apply, of course.	901	a watcher. The same limitations apply, of course.
841		902
842	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	903	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
843		904
844	Starts (activates) the given watcher. Only active watchers will receive	905	Starts (activates) the given watcher. Only active watchers will receive
…		…
927	to associate arbitrary data with your watcher. If you need more data and	988	to associate arbitrary data with your watcher. If you need more data and
928	don't want to allocate memory and store a pointer to it in that data	989	don't want to allocate memory and store a pointer to it in that data
929	member, you can also "subclass" the watcher type and provide your own	990	member, you can also "subclass" the watcher type and provide your own
930	data:	991	data:
931		992
932	struct my_io	993	struct my_io
933	{	994	{
934	struct ev_io io;	995	struct ev_io io;
935	int otherfd;	996	int otherfd;
936	void *somedata;	997	void *somedata;
937	struct whatever *mostinteresting;	998	struct whatever *mostinteresting;
938	}	999	}
939		1000
940	And since your callback will be called with a pointer to the watcher, you	1001	And since your callback will be called with a pointer to the watcher, you
941	can cast it back to your own type:	1002	can cast it back to your own type:
942		1003
943	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	1004	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
944	{	1005	{
945	struct my_io *w = (struct my_io *)w_;	1006	struct my_io *w = (struct my_io *)w_;
946	...	1007	...
947	}	1008	}
948		1009
949	More interesting and less C-conformant ways of casting your callback type	1010	More interesting and less C-conformant ways of casting your callback type
950	instead have been omitted.	1011	instead have been omitted.
951		1012
952	Another common scenario is having some data structure with multiple	1013	Another common scenario is having some data structure with multiple
953	watchers:	1014	watchers:
954		1015
955	struct my_biggy	1016	struct my_biggy
956	{	1017	{
957	int some_data;	1018	int some_data;
958	ev_timer t1;	1019	ev_timer t1;
959	ev_timer t2;	1020	ev_timer t2;
960	}	1021	}
961		1022
962	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1023	In this case getting the pointer to C<my_biggy> is a bit more complicated,
963	you need to use C<offsetof>:	1024	you need to use C<offsetof>:
964		1025
965	#include <stddef.h>	1026	#include <stddef.h>
966		1027
967	static void	1028	static void
968	t1_cb (EV_P_ struct ev_timer *w, int revents)	1029	t1_cb (EV_P_ struct ev_timer *w, int revents)
969	{	1030	{
970	struct my_biggy big = (struct my_biggy *	1031	struct my_biggy big = (struct my_biggy *
971	(((char *)w) - offsetof (struct my_biggy, t1));	1032	(((char *)w) - offsetof (struct my_biggy, t1));
972	}	1033	}
973		1034
974	static void	1035	static void
975	t2_cb (EV_P_ struct ev_timer *w, int revents)	1036	t2_cb (EV_P_ struct ev_timer *w, int revents)
976	{	1037	{
977	struct my_biggy big = (struct my_biggy *	1038	struct my_biggy big = (struct my_biggy *
978	(((char *)w) - offsetof (struct my_biggy, t2));	1039	(((char *)w) - offsetof (struct my_biggy, t2));
979	}	1040	}
980		1041
981		1042
982	=head1 WATCHER TYPES	1043	=head1 WATCHER TYPES
983		1044
984	This section describes each watcher in detail, but will not repeat	1045	This section describes each watcher in detail, but will not repeat
…		…
1013	If you must do this, then force the use of a known-to-be-good backend	1074	If you must do this, then force the use of a known-to-be-good backend
1014	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1075	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1015	C<EVBACKEND_POLL>).	1076	C<EVBACKEND_POLL>).
1016		1077
1017	Another thing you have to watch out for is that it is quite easy to	1078	Another thing you have to watch out for is that it is quite easy to
1018	receive "spurious" readyness notifications, that is your callback might	1079	receive "spurious" readiness notifications, that is your callback might
1019	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1080	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1020	because there is no data. Not only are some backends known to create a	1081	because there is no data. Not only are some backends known to create a
1021	lot of those (for example solaris ports), it is very easy to get into	1082	lot of those (for example Solaris ports), it is very easy to get into
1022	this situation even with a relatively standard program structure. Thus	1083	this situation even with a relatively standard program structure. Thus
1023	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1084	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1024	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1085	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1025		1086
1026	If you cannot run the fd in non-blocking mode (for example you should not	1087	If you cannot run the fd in non-blocking mode (for example you should not
1027	play around with an Xlib connection), then you have to seperately re-test	1088	play around with an Xlib connection), then you have to separately re-test
1028	whether a file descriptor is really ready with a known-to-be good interface	1089	whether a file descriptor is really ready with a known-to-be good interface
1029	such as poll (fortunately in our Xlib example, Xlib already does this on	1090	such as poll (fortunately in our Xlib example, Xlib already does this on
1030	its own, so its quite safe to use).	1091	its own, so its quite safe to use).
1031		1092
1032	=head3 The special problem of disappearing file descriptors	1093	=head3 The special problem of disappearing file descriptors
…		…
1070	To support fork in your programs, you either have to call	1131	To support fork in your programs, you either have to call
1071	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,	1132	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
1072	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or	1133	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
1073	C<EVBACKEND_POLL>.	1134	C<EVBACKEND_POLL>.
1074		1135
		1136	=head3 The special problem of SIGPIPE
		1137
		1138	While not really specific to libev, it is easy to forget about SIGPIPE:
		1139	when reading from a pipe whose other end has been closed, your program
		1140	gets send a SIGPIPE, which, by default, aborts your program. For most
		1141	programs this is sensible behaviour, for daemons, this is usually
		1142	undesirable.
		1143
		1144	So when you encounter spurious, unexplained daemon exits, make sure you
		1145	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
		1146	somewhere, as that would have given you a big clue).
		1147
1075		1148
1076	=head3 Watcher-Specific Functions	1149	=head3 Watcher-Specific Functions
1077		1150
1078	=over 4	1151	=over 4
1079		1152
1080	=item ev_io_init (ev_io *, callback, int fd, int events)	1153	=item ev_io_init (ev_io *, callback, int fd, int events)
1081		1154
1082	=item ev_io_set (ev_io *, int fd, int events)	1155	=item ev_io_set (ev_io *, int fd, int events)
1083		1156
1084	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1157	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1085	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1158	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1086	C<EV_READ | EV_WRITE> to receive the given events.	1159	C<EV_READ | EV_WRITE> to receive the given events.
1087		1160
1088	=item int fd [read-only]	1161	=item int fd [read-only]
1089		1162
1090	The file descriptor being watched.	1163	The file descriptor being watched.
…		…
1099		1172
1100	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1173	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1101	readable, but only once. Since it is likely line-buffered, you could	1174	readable, but only once. Since it is likely line-buffered, you could
1102	attempt to read a whole line in the callback.	1175	attempt to read a whole line in the callback.
1103		1176
1104	static void	1177	static void
1105	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1178	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1106	{	1179	{
1107	ev_io_stop (loop, w);	1180	ev_io_stop (loop, w);
1108	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1181	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1109	}	1182	}
1110		1183
1111	...	1184	...
1112	struct ev_loop *loop = ev_default_init (0);	1185	struct ev_loop *loop = ev_default_init (0);
1113	struct ev_io stdin_readable;	1186	struct ev_io stdin_readable;
1114	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1187	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1115	ev_io_start (loop, &stdin_readable);	1188	ev_io_start (loop, &stdin_readable);
1116	ev_loop (loop, 0);	1189	ev_loop (loop, 0);
1117		1190
1118		1191
1119	=head2 C<ev_timer> - relative and optionally repeating timeouts	1192	=head2 C<ev_timer> - relative and optionally repeating timeouts
1120		1193
1121	Timer watchers are simple relative timers that generate an event after a	1194	Timer watchers are simple relative timers that generate an event after a
1122	given time, and optionally repeating in regular intervals after that.	1195	given time, and optionally repeating in regular intervals after that.
1123		1196
1124	The timers are based on real time, that is, if you register an event that	1197	The timers are based on real time, that is, if you register an event that
1125	times out after an hour and you reset your system clock to last years	1198	times out after an hour and you reset your system clock to January last
1126	time, it will still time out after (roughly) and hour. "Roughly" because	1199	year, it will still time out after (roughly) and hour. "Roughly" because
1127	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1200	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1128	monotonic clock option helps a lot here).	1201	monotonic clock option helps a lot here).
1129		1202
1130	The relative timeouts are calculated relative to the C<ev_now ()>	1203	The relative timeouts are calculated relative to the C<ev_now ()>
1131	time. This is usually the right thing as this timestamp refers to the time	1204	time. This is usually the right thing as this timestamp refers to the time
…		…
1133	you suspect event processing to be delayed and you I<need> to base the timeout	1206	you suspect event processing to be delayed and you I<need> to base the timeout
1134	on the current time, use something like this to adjust for this:	1207	on the current time, use something like this to adjust for this:
1135		1208
1136	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1209	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1137		1210
1138	The callback is guarenteed to be invoked only when its timeout has passed,	1211	The callback is guaranteed to be invoked only after its timeout has passed,
1139	but if multiple timers become ready during the same loop iteration then	1212	but if multiple timers become ready during the same loop iteration then
1140	order of execution is undefined.	1213	order of execution is undefined.
1141		1214
1142	=head3 Watcher-Specific Functions and Data Members	1215	=head3 Watcher-Specific Functions and Data Members
1143		1216
…		…
1145		1218
1146	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1219	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1147		1220
1148	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1221	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1149		1222
1150	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1223	Configure the timer to trigger after C<after> seconds. If C<repeat>
1151	C<0.>, then it will automatically be stopped. If it is positive, then the	1224	is C<0.>, then it will automatically be stopped once the timeout is
1152	timer will automatically be configured to trigger again C<repeat> seconds	1225	reached. If it is positive, then the timer will automatically be
1153	later, again, and again, until stopped manually.	1226	configured to trigger again C<repeat> seconds later, again, and again,
		1227	until stopped manually.
1154		1228
1155	The timer itself will do a best-effort at avoiding drift, that is, if you	1229	The timer itself will do a best-effort at avoiding drift, that is, if
1156	configure a timer to trigger every 10 seconds, then it will trigger at	1230	you configure a timer to trigger every 10 seconds, then it will normally
1157	exactly 10 second intervals. If, however, your program cannot keep up with	1231	trigger at exactly 10 second intervals. If, however, your program cannot
1158	the timer (because it takes longer than those 10 seconds to do stuff) the	1232	keep up with the timer (because it takes longer than those 10 seconds to
1159	timer will not fire more than once per event loop iteration.	1233	do stuff) the timer will not fire more than once per event loop iteration.
1160		1234
1161	=item ev_timer_again (loop, ev_timer *)	1235	=item ev_timer_again (loop, ev_timer *)
1162		1236
1163	This will act as if the timer timed out and restart it again if it is	1237	This will act as if the timer timed out and restart it again if it is
1164	repeating. The exact semantics are:	1238	repeating. The exact semantics are:
1165		1239
1166	If the timer is pending, its pending status is cleared.	1240	If the timer is pending, its pending status is cleared.
1167		1241
1168	If the timer is started but nonrepeating, stop it (as if it timed out).	1242	If the timer is started but non-repeating, stop it (as if it timed out).
1169		1243
1170	If the timer is repeating, either start it if necessary (with the	1244	If the timer is repeating, either start it if necessary (with the
1171	C<repeat> value), or reset the running timer to the C<repeat> value.	1245	C<repeat> value), or reset the running timer to the C<repeat> value.
1172		1246
1173	This sounds a bit complicated, but here is a useful and typical	1247	This sounds a bit complicated, but here is a useful and typical
1174	example: Imagine you have a tcp connection and you want a so-called idle	1248	example: Imagine you have a TCP connection and you want a so-called idle
1175	timeout, that is, you want to be called when there have been, say, 60	1249	timeout, that is, you want to be called when there have been, say, 60
1176	seconds of inactivity on the socket. The easiest way to do this is to	1250	seconds of inactivity on the socket. The easiest way to do this is to
1177	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1251	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1178	C<ev_timer_again> each time you successfully read or write some data. If	1252	C<ev_timer_again> each time you successfully read or write some data. If
1179	you go into an idle state where you do not expect data to travel on the	1253	you go into an idle state where you do not expect data to travel on the
…		…
1205		1279
1206	=head3 Examples	1280	=head3 Examples
1207		1281
1208	Example: Create a timer that fires after 60 seconds.	1282	Example: Create a timer that fires after 60 seconds.
1209		1283
1210	static void	1284	static void
1211	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1285	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1212	{	1286	{
1213	.. one minute over, w is actually stopped right here	1287	.. one minute over, w is actually stopped right here
1214	}	1288	}
1215		1289
1216	struct ev_timer mytimer;	1290	struct ev_timer mytimer;
1217	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1291	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1218	ev_timer_start (loop, &mytimer);	1292	ev_timer_start (loop, &mytimer);
1219		1293
1220	Example: Create a timeout timer that times out after 10 seconds of	1294	Example: Create a timeout timer that times out after 10 seconds of
1221	inactivity.	1295	inactivity.
1222		1296
1223	static void	1297	static void
1224	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1298	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1225	{	1299	{
1226	.. ten seconds without any activity	1300	.. ten seconds without any activity
1227	}	1301	}
1228		1302
1229	struct ev_timer mytimer;	1303	struct ev_timer mytimer;
1230	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1304	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1231	ev_timer_again (&mytimer); /* start timer */	1305	ev_timer_again (&mytimer); /* start timer */
1232	ev_loop (loop, 0);	1306	ev_loop (loop, 0);
1233		1307
1234	// and in some piece of code that gets executed on any "activity":	1308	// and in some piece of code that gets executed on any "activity":
1235	// reset the timeout to start ticking again at 10 seconds	1309	// reset the timeout to start ticking again at 10 seconds
1236	ev_timer_again (&mytimer);	1310	ev_timer_again (&mytimer);
1237		1311
1238		1312
1239	=head2 C<ev_periodic> - to cron or not to cron?	1313	=head2 C<ev_periodic> - to cron or not to cron?
1240		1314
1241	Periodic watchers are also timers of a kind, but they are very versatile	1315	Periodic watchers are also timers of a kind, but they are very versatile
1242	(and unfortunately a bit complex).	1316	(and unfortunately a bit complex).
1243		1317
1244	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1318	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1245	but on wallclock time (absolute time). You can tell a periodic watcher	1319	but on wall clock time (absolute time). You can tell a periodic watcher
1246	to trigger "at" some specific point in time. For example, if you tell a	1320	to trigger after some specific point in time. For example, if you tell a
1247	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1321	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1248	+ 10.>) and then reset your system clock to the last year, then it will	1322	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1323	clock to January of the previous year, then it will take more than year
1249	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1324	to trigger the event (unlike an C<ev_timer>, which would still trigger
1250	roughly 10 seconds later).	1325	roughly 10 seconds later as it uses a relative timeout).
1251		1326
1252	They can also be used to implement vastly more complex timers, such as	1327	C<ev_periodic>s can also be used to implement vastly more complex timers,
1253	triggering an event on each midnight, local time or other, complicated,	1328	such as triggering an event on each "midnight, local time", or other
1254	rules.	1329	complicated, rules.
1255		1330
1256	As with timers, the callback is guarenteed to be invoked only when the	1331	As with timers, the callback is guaranteed to be invoked only when the
1257	time (C<at>) has been passed, but if multiple periodic timers become ready	1332	time (C<at>) has passed, but if multiple periodic timers become ready
1258	during the same loop iteration then order of execution is undefined.	1333	during the same loop iteration then order of execution is undefined.
1259		1334
1260	=head3 Watcher-Specific Functions and Data Members	1335	=head3 Watcher-Specific Functions and Data Members
1261		1336
1262	=over 4	1337	=over 4
…		…
1270		1345
1271	=over 4	1346	=over 4
1272		1347
1273	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1348	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1274		1349
1275	In this configuration the watcher triggers an event at the wallclock time	1350	In this configuration the watcher triggers an event after the wall clock
1276	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1351	time C<at> has passed and doesn't repeat. It will not adjust when a time
1277	that is, if it is to be run at January 1st 2011 then it will run when the	1352	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1278	system time reaches or surpasses this time.	1353	run when the system time reaches or surpasses this time.
1279		1354
1280	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1355	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1281		1356
1282	In this mode the watcher will always be scheduled to time out at the next	1357	In this mode the watcher will always be scheduled to time out at the next
1283	C<at + N * interval> time (for some integer N, which can also be negative)	1358	C<at + N * interval> time (for some integer N, which can also be negative)
1284	and then repeat, regardless of any time jumps.	1359	and then repeat, regardless of any time jumps.
1285		1360
1286	This can be used to create timers that do not drift with respect to system	1361	This can be used to create timers that do not drift with respect to system
1287	time:	1362	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1363	the hour:
1288		1364
1289	ev_periodic_set (&periodic, 0., 3600., 0);	1365	ev_periodic_set (&periodic, 0., 3600., 0);
1290		1366
1291	This doesn't mean there will always be 3600 seconds in between triggers,	1367	This doesn't mean there will always be 3600 seconds in between triggers,
1292	but only that the the callback will be called when the system time shows a	1368	but only that the callback will be called when the system time shows a
1293	full hour (UTC), or more correctly, when the system time is evenly divisible	1369	full hour (UTC), or more correctly, when the system time is evenly divisible
1294	by 3600.	1370	by 3600.
1295		1371
1296	Another way to think about it (for the mathematically inclined) is that	1372	Another way to think about it (for the mathematically inclined) is that
1297	C<ev_periodic> will try to run the callback in this mode at the next possible	1373	C<ev_periodic> will try to run the callback in this mode at the next possible
1298	time where C<time = at (mod interval)>, regardless of any time jumps.	1374	time where C<time = at (mod interval)>, regardless of any time jumps.
1299		1375
1300	For numerical stability it is preferable that the C<at> value is near	1376	For numerical stability it is preferable that the C<at> value is near
1301	C<ev_now ()> (the current time), but there is no range requirement for	1377	C<ev_now ()> (the current time), but there is no range requirement for
1302	this value.	1378	this value, and in fact is often specified as zero.
		1379
		1380	Note also that there is an upper limit to how often a timer can fire (CPU
		1381	speed for example), so if C<interval> is very small then timing stability
		1382	will of course deteriorate. Libev itself tries to be exact to be about one
		1383	millisecond (if the OS supports it and the machine is fast enough).
1303		1384
1304	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1385	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1305		1386
1306	In this mode the values for C<interval> and C<at> are both being	1387	In this mode the values for C<interval> and C<at> are both being
1307	ignored. Instead, each time the periodic watcher gets scheduled, the	1388	ignored. Instead, each time the periodic watcher gets scheduled, the
1308	reschedule callback will be called with the watcher as first, and the	1389	reschedule callback will be called with the watcher as first, and the
1309	current time as second argument.	1390	current time as second argument.
1310		1391
1311	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1392	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1312	ever, or make any event loop modifications>. If you need to stop it,	1393	ever, or make ANY event loop modifications whatsoever>.
1313	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1314	starting an C<ev_prepare> watcher, which is legal).
1315		1394
		1395	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1396	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1397	only event loop modification you are allowed to do).
		1398
1316	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1399	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1317	ev_tstamp now)>, e.g.:	1400	*w, ev_tstamp now)>, e.g.:
1318		1401
1319	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1402	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1320	{	1403	{
1321	return now + 60.;	1404	return now + 60.;
1322	}	1405	}
…		…
1324	It must return the next time to trigger, based on the passed time value	1407	It must return the next time to trigger, based on the passed time value
1325	(that is, the lowest time value larger than to the second argument). It	1408	(that is, the lowest time value larger than to the second argument). It
1326	will usually be called just before the callback will be triggered, but	1409	will usually be called just before the callback will be triggered, but
1327	might be called at other times, too.	1410	might be called at other times, too.
1328		1411
1329	NOTE: I<< This callback must always return a time that is later than the	1412	NOTE: I<< This callback must always return a time that is higher than or
1330	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1413	equal to the passed C<now> value >>.
1331		1414
1332	This can be used to create very complex timers, such as a timer that	1415	This can be used to create very complex timers, such as a timer that
1333	triggers on each midnight, local time. To do this, you would calculate the	1416	triggers on "next midnight, local time". To do this, you would calculate the
1334	next midnight after C<now> and return the timestamp value for this. How	1417	next midnight after C<now> and return the timestamp value for this. How
1335	you do this is, again, up to you (but it is not trivial, which is the main	1418	you do this is, again, up to you (but it is not trivial, which is the main
1336	reason I omitted it as an example).	1419	reason I omitted it as an example).
1337		1420
1338	=back	1421	=back
…		…
1342	Simply stops and restarts the periodic watcher again. This is only useful	1425	Simply stops and restarts the periodic watcher again. This is only useful
1343	when you changed some parameters or the reschedule callback would return	1426	when you changed some parameters or the reschedule callback would return
1344	a different time than the last time it was called (e.g. in a crond like	1427	a different time than the last time it was called (e.g. in a crond like
1345	program when the crontabs have changed).	1428	program when the crontabs have changed).
1346		1429
		1430	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1431
		1432	When active, returns the absolute time that the watcher is supposed to
		1433	trigger next.
		1434
1347	=item ev_tstamp offset [read-write]	1435	=item ev_tstamp offset [read-write]
1348		1436
1349	When repeating, this contains the offset value, otherwise this is the	1437	When repeating, this contains the offset value, otherwise this is the
1350	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1438	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1351		1439
…		…
1362		1450
1363	The current reschedule callback, or C<0>, if this functionality is	1451	The current reschedule callback, or C<0>, if this functionality is
1364	switched off. Can be changed any time, but changes only take effect when	1452	switched off. Can be changed any time, but changes only take effect when
1365	the periodic timer fires or C<ev_periodic_again> is being called.	1453	the periodic timer fires or C<ev_periodic_again> is being called.
1366		1454
1367	=item ev_tstamp at [read-only]
1368
1369	When active, contains the absolute time that the watcher is supposed to
1370	trigger next.
1371
1372	=back	1455	=back
1373		1456
1374	=head3 Examples	1457	=head3 Examples
1375		1458
1376	Example: Call a callback every hour, or, more precisely, whenever the	1459	Example: Call a callback every hour, or, more precisely, whenever the
1377	system clock is divisible by 3600. The callback invocation times have	1460	system clock is divisible by 3600. The callback invocation times have
1378	potentially a lot of jittering, but good long-term stability.	1461	potentially a lot of jitter, but good long-term stability.
1379		1462
1380	static void	1463	static void
1381	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1464	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1382	{	1465	{
1383	... its now a full hour (UTC, or TAI or whatever your clock follows)	1466	... its now a full hour (UTC, or TAI or whatever your clock follows)
1384	}	1467	}
1385		1468
1386	struct ev_periodic hourly_tick;	1469	struct ev_periodic hourly_tick;
1387	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1470	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1388	ev_periodic_start (loop, &hourly_tick);	1471	ev_periodic_start (loop, &hourly_tick);
1389		1472
1390	Example: The same as above, but use a reschedule callback to do it:	1473	Example: The same as above, but use a reschedule callback to do it:
1391		1474
1392	#include <math.h>	1475	#include <math.h>
1393		1476
1394	static ev_tstamp	1477	static ev_tstamp
1395	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1478	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1396	{	1479	{
1397	return fmod (now, 3600.) + 3600.;	1480	return fmod (now, 3600.) + 3600.;
1398	}	1481	}
1399		1482
1400	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1483	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1401		1484
1402	Example: Call a callback every hour, starting now:	1485	Example: Call a callback every hour, starting now:
1403		1486
1404	struct ev_periodic hourly_tick;	1487	struct ev_periodic hourly_tick;
1405	ev_periodic_init (&hourly_tick, clock_cb,	1488	ev_periodic_init (&hourly_tick, clock_cb,
1406	fmod (ev_now (loop), 3600.), 3600., 0);	1489	fmod (ev_now (loop), 3600.), 3600., 0);
1407	ev_periodic_start (loop, &hourly_tick);	1490	ev_periodic_start (loop, &hourly_tick);
1408		1491
1409		1492
1410	=head2 C<ev_signal> - signal me when a signal gets signalled!	1493	=head2 C<ev_signal> - signal me when a signal gets signalled!
1411		1494
1412	Signal watchers will trigger an event when the process receives a specific	1495	Signal watchers will trigger an event when the process receives a specific
…		…
1419	with the kernel (thus it coexists with your own signal handlers as long	1502	with the kernel (thus it coexists with your own signal handlers as long
1420	as you don't register any with libev). Similarly, when the last signal	1503	as you don't register any with libev). Similarly, when the last signal
1421	watcher for a signal is stopped libev will reset the signal handler to	1504	watcher for a signal is stopped libev will reset the signal handler to
1422	SIG_DFL (regardless of what it was set to before).	1505	SIG_DFL (regardless of what it was set to before).
1423		1506
		1507	If possible and supported, libev will install its handlers with
		1508	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
		1509	interrupted. If you have a problem with system calls getting interrupted by
		1510	signals you can block all signals in an C<ev_check> watcher and unblock
		1511	them in an C<ev_prepare> watcher.
		1512
1424	=head3 Watcher-Specific Functions and Data Members	1513	=head3 Watcher-Specific Functions and Data Members
1425		1514
1426	=over 4	1515	=over 4
1427		1516
1428	=item ev_signal_init (ev_signal *, callback, int signum)	1517	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
1440		1529
1441	=head3 Examples	1530	=head3 Examples
1442		1531
1443	Example: Try to exit cleanly on SIGINT and SIGTERM.	1532	Example: Try to exit cleanly on SIGINT and SIGTERM.
1444		1533
1445	static void	1534	static void
1446	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1535	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1447	{	1536	{
1448	ev_unloop (loop, EVUNLOOP_ALL);	1537	ev_unloop (loop, EVUNLOOP_ALL);
1449	}	1538	}
1450		1539
1451	struct ev_signal signal_watcher;	1540	struct ev_signal signal_watcher;
1452	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1541	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1453	ev_signal_start (loop, &sigint_cb);	1542	ev_signal_start (loop, &sigint_cb);
1454		1543
1455		1544
1456	=head2 C<ev_child> - watch out for process status changes	1545	=head2 C<ev_child> - watch out for process status changes
1457		1546
1458	Child watchers trigger when your process receives a SIGCHLD in response to	1547	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1460	is permissible to install a child watcher I<after> the child has been	1549	is permissible to install a child watcher I<after> the child has been
1461	forked (which implies it might have already exited), as long as the event	1550	forked (which implies it might have already exited), as long as the event
1462	loop isn't entered (or is continued from a watcher).	1551	loop isn't entered (or is continued from a watcher).
1463		1552
1464	Only the default event loop is capable of handling signals, and therefore	1553	Only the default event loop is capable of handling signals, and therefore
1465	you can only rgeister child watchers in the default event loop.	1554	you can only register child watchers in the default event loop.
1466		1555
1467	=head3 Process Interaction	1556	=head3 Process Interaction
1468		1557
1469	Libev grabs C<SIGCHLD> as soon as the default event loop is	1558	Libev grabs C<SIGCHLD> as soon as the default event loop is
1470	initialised. This is necessary to guarantee proper behaviour even if	1559	initialised. This is necessary to guarantee proper behaviour even if
1471	the first child watcher is started after the child exits. The occurance	1560	the first child watcher is started after the child exits. The occurrence
1472	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1561	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1473	synchronously as part of the event loop processing. Libev always reaps all	1562	synchronously as part of the event loop processing. Libev always reaps all
1474	children, even ones not watched.	1563	children, even ones not watched.
1475		1564
1476	=head3 Overriding the Built-In Processing	1565	=head3 Overriding the Built-In Processing
…		…
1518	=head3 Examples	1607	=head3 Examples
1519		1608
1520	Example: C<fork()> a new process and install a child handler to wait for	1609	Example: C<fork()> a new process and install a child handler to wait for
1521	its completion.	1610	its completion.
1522		1611
1523	ev_child cw;	1612	ev_child cw;
1524		1613
1525	static void	1614	static void
1526	child_cb (EV_P_ struct ev_child *w, int revents)	1615	child_cb (EV_P_ struct ev_child *w, int revents)
1527	{	1616	{
1528	ev_child_stop (EV_A_ w);	1617	ev_child_stop (EV_A_ w);
1529	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1618	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1530	}	1619	}
1531		1620
1532	pid_t pid = fork ();	1621	pid_t pid = fork ();
1533		1622
1534	if (pid < 0)	1623	if (pid < 0)
1535	// error	1624	// error
1536	else if (pid == 0)	1625	else if (pid == 0)
1537	{	1626	{
1538	// the forked child executes here	1627	// the forked child executes here
1539	exit (1);	1628	exit (1);
1540	}	1629	}
1541	else	1630	else
1542	{	1631	{
1543	ev_child_init (&cw, child_cb, pid, 0);	1632	ev_child_init (&cw, child_cb, pid, 0);
1544	ev_child_start (EV_DEFAULT_ &cw);	1633	ev_child_start (EV_DEFAULT_ &cw);
1545	}	1634	}
1546		1635
1547		1636
1548	=head2 C<ev_stat> - did the file attributes just change?	1637	=head2 C<ev_stat> - did the file attributes just change?
1549		1638
1550	This watches a filesystem path for attribute changes. That is, it calls	1639	This watches a file system path for attribute changes. That is, it calls
1551	C<stat> regularly (or when the OS says it changed) and sees if it changed	1640	C<stat> regularly (or when the OS says it changed) and sees if it changed
1552	compared to the last time, invoking the callback if it did.	1641	compared to the last time, invoking the callback if it did.
1553		1642
1554	The path does not need to exist: changing from "path exists" to "path does	1643	The path does not need to exist: changing from "path exists" to "path does
1555	not exist" is a status change like any other. The condition "path does	1644	not exist" is a status change like any other. The condition "path does
…		…
1573	as even with OS-supported change notifications, this can be	1662	as even with OS-supported change notifications, this can be
1574	resource-intensive.	1663	resource-intensive.
1575		1664
1576	At the time of this writing, only the Linux inotify interface is	1665	At the time of this writing, only the Linux inotify interface is
1577	implemented (implementing kqueue support is left as an exercise for the	1666	implemented (implementing kqueue support is left as an exercise for the
		1667	reader, note, however, that the author sees no way of implementing ev_stat
1578	reader). Inotify will be used to give hints only and should not change the	1668	semantics with kqueue). Inotify will be used to give hints only and should
1579	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1669	not change the semantics of C<ev_stat> watchers, which means that libev
1580	to fall back to regular polling again even with inotify, but changes are	1670	sometimes needs to fall back to regular polling again even with inotify,
1581	usually detected immediately, and if the file exists there will be no	1671	but changes are usually detected immediately, and if the file exists there
1582	polling.	1672	will be no polling.
		1673
		1674	=head3 ABI Issues (Largefile Support)
		1675
		1676	Libev by default (unless the user overrides this) uses the default
		1677	compilation environment, which means that on systems with large file
		1678	support disabled by default, you get the 32 bit version of the stat
		1679	structure. When using the library from programs that change the ABI to
		1680	use 64 bit file offsets the programs will fail. In that case you have to
		1681	compile libev with the same flags to get binary compatibility. This is
		1682	obviously the case with any flags that change the ABI, but the problem is
		1683	most noticeably disabled with ev_stat and large file support.
		1684
		1685	The solution for this is to lobby your distribution maker to make large
		1686	file interfaces available by default (as e.g. FreeBSD does) and not
		1687	optional. Libev cannot simply switch on large file support because it has
		1688	to exchange stat structures with application programs compiled using the
		1689	default compilation environment.
1583		1690
1584	=head3 Inotify	1691	=head3 Inotify
1585		1692
1586	When C<inotify (7)> support has been compiled into libev (generally only	1693	When C<inotify (7)> support has been compiled into libev (generally only
1587	available on Linux) and present at runtime, it will be used to speed up	1694	available on Linux) and present at runtime, it will be used to speed up
1588	change detection where possible. The inotify descriptor will be created lazily	1695	change detection where possible. The inotify descriptor will be created lazily
1589	when the first C<ev_stat> watcher is being started.	1696	when the first C<ev_stat> watcher is being started.
1590		1697
1591	Inotify presense does not change the semantics of C<ev_stat> watchers	1698	Inotify presence does not change the semantics of C<ev_stat> watchers
1592	except that changes might be detected earlier, and in some cases, to avoid	1699	except that changes might be detected earlier, and in some cases, to avoid
1593	making regular C<stat> calls. Even in the presense of inotify support	1700	making regular C<stat> calls. Even in the presence of inotify support
1594	there are many cases where libev has to resort to regular C<stat> polling.	1701	there are many cases where libev has to resort to regular C<stat> polling.
1595		1702
1596	(There is no support for kqueue, as apparently it cannot be used to	1703	(There is no support for kqueue, as apparently it cannot be used to
1597	implement this functionality, due to the requirement of having a file	1704	implement this functionality, due to the requirement of having a file
1598	descriptor open on the object at all times).	1705	descriptor open on the object at all times).
1599		1706
1600	=head3 The special problem of stat time resolution	1707	=head3 The special problem of stat time resolution
1601		1708
1602	The C<stat ()> syscall only supports full-second resolution portably, and	1709	The C<stat ()> system call only supports full-second resolution portably, and
1603	even on systems where the resolution is higher, many filesystems still	1710	even on systems where the resolution is higher, many file systems still
1604	only support whole seconds.	1711	only support whole seconds.
1605		1712
1606	That means that, if the time is the only thing that changes, you might	1713	That means that, if the time is the only thing that changes, you can
1607	miss updates: on the first update, C<ev_stat> detects a change and calls	1714	easily miss updates: on the first update, C<ev_stat> detects a change and
1608	your callback, which does something. When there is another update within	1715	calls your callback, which does something. When there is another update
1609	the same second, C<ev_stat> will be unable to detect it.	1716	within the same second, C<ev_stat> will be unable to detect it as the stat
		1717	data does not change.
1610		1718
1611	The solution to this is to delay acting on a change for a second (or till	1719	The solution to this is to delay acting on a change for slightly more
1612	the next second boundary), using a roughly one-second delay C<ev_timer>	1720	than a second (or till slightly after the next full second boundary), using
1613	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1721	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1614	is added to work around small timing inconsistencies of some operating	1722	ev_timer_again (loop, w)>).
1615	systems.	1723
		1724	The C<.02> offset is added to work around small timing inconsistencies
		1725	of some operating systems (where the second counter of the current time
		1726	might be be delayed. One such system is the Linux kernel, where a call to
		1727	C<gettimeofday> might return a timestamp with a full second later than
		1728	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1729	update file times then there will be a small window where the kernel uses
		1730	the previous second to update file times but libev might already execute
		1731	the timer callback).
1616		1732
1617	=head3 Watcher-Specific Functions and Data Members	1733	=head3 Watcher-Specific Functions and Data Members
1618		1734
1619	=over 4	1735	=over 4
1620		1736
…		…
1626	C<path>. The C<interval> is a hint on how quickly a change is expected to	1742	C<path>. The C<interval> is a hint on how quickly a change is expected to
1627	be detected and should normally be specified as C<0> to let libev choose	1743	be detected and should normally be specified as C<0> to let libev choose
1628	a suitable value. The memory pointed to by C<path> must point to the same	1744	a suitable value. The memory pointed to by C<path> must point to the same
1629	path for as long as the watcher is active.	1745	path for as long as the watcher is active.
1630		1746
1631	The callback will be receive C<EV_STAT> when a change was detected,	1747	The callback will receive C<EV_STAT> when a change was detected, relative
1632	relative to the attributes at the time the watcher was started (or the	1748	to the attributes at the time the watcher was started (or the last change
1633	last change was detected).	1749	was detected).
1634		1750
1635	=item ev_stat_stat (loop, ev_stat *)	1751	=item ev_stat_stat (loop, ev_stat *)
1636		1752
1637	Updates the stat buffer immediately with new values. If you change the	1753	Updates the stat buffer immediately with new values. If you change the
1638	watched path in your callback, you could call this fucntion to avoid	1754	watched path in your callback, you could call this function to avoid
1639	detecting this change (while introducing a race condition). Can also be	1755	detecting this change (while introducing a race condition if you are not
1640	useful simply to find out the new values.	1756	the only one changing the path). Can also be useful simply to find out the
		1757	new values.
1641		1758
1642	=item ev_statdata attr [read-only]	1759	=item ev_statdata attr [read-only]
1643		1760
1644	The most-recently detected attributes of the file. Although the type is of	1761	The most-recently detected attributes of the file. Although the type is
1645	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1762	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1646	suitable for your system. If the C<st_nlink> member is C<0>, then there	1763	suitable for your system, but you can only rely on the POSIX-standardised
		1764	members to be present. If the C<st_nlink> member is C<0>, then there was
1647	was some error while C<stat>ing the file.	1765	some error while C<stat>ing the file.
1648		1766
1649	=item ev_statdata prev [read-only]	1767	=item ev_statdata prev [read-only]
1650		1768
1651	The previous attributes of the file. The callback gets invoked whenever	1769	The previous attributes of the file. The callback gets invoked whenever
1652	C<prev> != C<attr>.	1770	C<prev> != C<attr>, or, more precisely, one or more of these members
		1771	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1772	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1653		1773
1654	=item ev_tstamp interval [read-only]	1774	=item ev_tstamp interval [read-only]
1655		1775
1656	The specified interval.	1776	The specified interval.
1657		1777
1658	=item const char *path [read-only]	1778	=item const char *path [read-only]
1659		1779
1660	The filesystem path that is being watched.	1780	The file system path that is being watched.
1661		1781
1662	=back	1782	=back
1663		1783
1664	=head3 Examples	1784	=head3 Examples
1665		1785
1666	Example: Watch C</etc/passwd> for attribute changes.	1786	Example: Watch C</etc/passwd> for attribute changes.
1667		1787
1668	static void	1788	static void
1669	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1789	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1670	{	1790	{
1671	/* /etc/passwd changed in some way */	1791	/* /etc/passwd changed in some way */
1672	if (w->attr.st_nlink)	1792	if (w->attr.st_nlink)
1673	{	1793	{
1674	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1794	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1675	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1795	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1676	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1796	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1677	}	1797	}
1678	else	1798	else
1679	/* you shalt not abuse printf for puts */	1799	/* you shalt not abuse printf for puts */
1680	puts ("wow, /etc/passwd is not there, expect problems. "	1800	puts ("wow, /etc/passwd is not there, expect problems. "
1681	"if this is windows, they already arrived\n");	1801	"if this is windows, they already arrived\n");
1682	}	1802	}
1683		1803
1684	...	1804	...
1685	ev_stat passwd;	1805	ev_stat passwd;
1686		1806
1687	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1807	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1688	ev_stat_start (loop, &passwd);	1808	ev_stat_start (loop, &passwd);
1689		1809
1690	Example: Like above, but additionally use a one-second delay so we do not	1810	Example: Like above, but additionally use a one-second delay so we do not
1691	miss updates (however, frequent updates will delay processing, too, so	1811	miss updates (however, frequent updates will delay processing, too, so
1692	one might do the work both on C<ev_stat> callback invocation I<and> on	1812	one might do the work both on C<ev_stat> callback invocation I<and> on
1693	C<ev_timer> callback invocation).	1813	C<ev_timer> callback invocation).
1694		1814
1695	static ev_stat passwd;	1815	static ev_stat passwd;
1696	static ev_timer timer;	1816	static ev_timer timer;
1697		1817
1698	static void	1818	static void
1699	timer_cb (EV_P_ ev_timer *w, int revents)	1819	timer_cb (EV_P_ ev_timer *w, int revents)
1700	{	1820	{
1701	ev_timer_stop (EV_A_ w);	1821	ev_timer_stop (EV_A_ w);
1702		1822
1703	/* now it's one second after the most recent passwd change */	1823	/* now it's one second after the most recent passwd change */
1704	}	1824	}
1705		1825
1706	static void	1826	static void
1707	stat_cb (EV_P_ ev_stat *w, int revents)	1827	stat_cb (EV_P_ ev_stat *w, int revents)
1708	{	1828	{
1709	/* reset the one-second timer */	1829	/* reset the one-second timer */
1710	ev_timer_again (EV_A_ &timer);	1830	ev_timer_again (EV_A_ &timer);
1711	}	1831	}
1712		1832
1713	...	1833	...
1714	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1834	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1715	ev_stat_start (loop, &passwd);	1835	ev_stat_start (loop, &passwd);
1716	ev_timer_init (&timer, timer_cb, 0., 1.01);	1836	ev_timer_init (&timer, timer_cb, 0., 1.02);
1717		1837
1718		1838
1719	=head2 C<ev_idle> - when you've got nothing better to do...	1839	=head2 C<ev_idle> - when you've got nothing better to do...
1720		1840
1721	Idle watchers trigger events when no other events of the same or higher	1841	Idle watchers trigger events when no other events of the same or higher
…		…
1752	=head3 Examples	1872	=head3 Examples
1753		1873
1754	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1874	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1755	callback, free it. Also, use no error checking, as usual.	1875	callback, free it. Also, use no error checking, as usual.
1756		1876
1757	static void	1877	static void
1758	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1878	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1759	{	1879	{
1760	free (w);	1880	free (w);
1761	// now do something you wanted to do when the program has	1881	// now do something you wanted to do when the program has
1762	// no longer anything immediate to do.	1882	// no longer anything immediate to do.
1763	}	1883	}
1764		1884
1765	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1885	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1766	ev_idle_init (idle_watcher, idle_cb);	1886	ev_idle_init (idle_watcher, idle_cb);
1767	ev_idle_start (loop, idle_cb);	1887	ev_idle_start (loop, idle_cb);
1768		1888
1769		1889
1770	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1890	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1771		1891
1772	Prepare and check watchers are usually (but not always) used in tandem:	1892	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1791		1911
1792	This is done by examining in each prepare call which file descriptors need	1912	This is done by examining in each prepare call which file descriptors need
1793	to be watched by the other library, registering C<ev_io> watchers for	1913	to be watched by the other library, registering C<ev_io> watchers for
1794	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1914	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1795	provide just this functionality). Then, in the check watcher you check for	1915	provide just this functionality). Then, in the check watcher you check for
1796	any events that occured (by checking the pending status of all watchers	1916	any events that occurred (by checking the pending status of all watchers
1797	and stopping them) and call back into the library. The I/O and timer	1917	and stopping them) and call back into the library. The I/O and timer
1798	callbacks will never actually be called (but must be valid nevertheless,	1918	callbacks will never actually be called (but must be valid nevertheless,
1799	because you never know, you know?).	1919	because you never know, you know?).
1800		1920
1801	As another example, the Perl Coro module uses these hooks to integrate	1921	As another example, the Perl Coro module uses these hooks to integrate
…		…
1809		1929
1810	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1930	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1811	priority, to ensure that they are being run before any other watchers	1931	priority, to ensure that they are being run before any other watchers
1812	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1932	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1813	too) should not activate ("feed") events into libev. While libev fully	1933	too) should not activate ("feed") events into libev. While libev fully
1814	supports this, they will be called before other C<ev_check> watchers	1934	supports this, they might get executed before other C<ev_check> watchers
1815	did their job. As C<ev_check> watchers are often used to embed other	1935	did their job. As C<ev_check> watchers are often used to embed other
1816	(non-libev) event loops those other event loops might be in an unusable	1936	(non-libev) event loops those other event loops might be in an unusable
1817	state until their C<ev_check> watcher ran (always remind yourself to	1937	state until their C<ev_check> watcher ran (always remind yourself to
1818	coexist peacefully with others).	1938	coexist peacefully with others).
1819		1939
…		…
1834	=head3 Examples	1954	=head3 Examples
1835		1955
1836	There are a number of principal ways to embed other event loops or modules	1956	There are a number of principal ways to embed other event loops or modules
1837	into libev. Here are some ideas on how to include libadns into libev	1957	into libev. Here are some ideas on how to include libadns into libev
1838	(there is a Perl module named C<EV::ADNS> that does this, which you could	1958	(there is a Perl module named C<EV::ADNS> that does this, which you could
1839	use for an actually working example. Another Perl module named C<EV::Glib>	1959	use as a working example. Another Perl module named C<EV::Glib> embeds a
1840	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	1960	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1841	into the Glib event loop).	1961	Glib event loop).
1842		1962
1843	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1963	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1844	and in a check watcher, destroy them and call into libadns. What follows	1964	and in a check watcher, destroy them and call into libadns. What follows
1845	is pseudo-code only of course. This requires you to either use a low	1965	is pseudo-code only of course. This requires you to either use a low
1846	priority for the check watcher or use C<ev_clear_pending> explicitly, as	1966	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1847	the callbacks for the IO/timeout watchers might not have been called yet.	1967	the callbacks for the IO/timeout watchers might not have been called yet.
1848		1968
1849	static ev_io iow [nfd];	1969	static ev_io iow [nfd];
1850	static ev_timer tw;	1970	static ev_timer tw;
1851		1971
1852	static void	1972	static void
1853	io_cb (ev_loop *loop, ev_io *w, int revents)	1973	io_cb (ev_loop *loop, ev_io *w, int revents)
1854	{	1974	{
1855	}	1975	}
1856		1976
1857	// create io watchers for each fd and a timer before blocking	1977	// create io watchers for each fd and a timer before blocking
1858	static void	1978	static void
1859	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1979	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1860	{	1980	{
1861	int timeout = 3600000;	1981	int timeout = 3600000;
1862	struct pollfd fds [nfd];	1982	struct pollfd fds [nfd];
1863	// actual code will need to loop here and realloc etc.	1983	// actual code will need to loop here and realloc etc.
1864	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1984	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1865		1985
1866	/* the callback is illegal, but won't be called as we stop during check */	1986	/* the callback is illegal, but won't be called as we stop during check */
1867	ev_timer_init (&tw, 0, timeout * 1e-3);	1987	ev_timer_init (&tw, 0, timeout * 1e-3);
1868	ev_timer_start (loop, &tw);	1988	ev_timer_start (loop, &tw);
1869		1989
1870	// create one ev_io per pollfd	1990	// create one ev_io per pollfd
1871	for (int i = 0; i < nfd; ++i)	1991	for (int i = 0; i < nfd; ++i)
1872	{	1992	{
1873	ev_io_init (iow + i, io_cb, fds [i].fd,	1993	ev_io_init (iow + i, io_cb, fds [i].fd,
1874	((fds [i].events & POLLIN ? EV_READ : 0)	1994	((fds [i].events & POLLIN ? EV_READ : 0)
1875	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1995	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1876		1996
1877	fds [i].revents = 0;	1997	fds [i].revents = 0;
1878	ev_io_start (loop, iow + i);	1998	ev_io_start (loop, iow + i);
1879	}	1999	}
1880	}	2000	}
1881		2001
1882	// stop all watchers after blocking	2002	// stop all watchers after blocking
1883	static void	2003	static void
1884	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	2004	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1885	{	2005	{
1886	ev_timer_stop (loop, &tw);	2006	ev_timer_stop (loop, &tw);
1887		2007
1888	for (int i = 0; i < nfd; ++i)	2008	for (int i = 0; i < nfd; ++i)
1889	{	2009	{
1890	// set the relevant poll flags	2010	// set the relevant poll flags
1891	// could also call adns_processreadable etc. here	2011	// could also call adns_processreadable etc. here
1892	struct pollfd *fd = fds + i;	2012	struct pollfd *fd = fds + i;
1893	int revents = ev_clear_pending (iow + i);	2013	int revents = ev_clear_pending (iow + i);
1894	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2014	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1895	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2015	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1896		2016
1897	// now stop the watcher	2017	// now stop the watcher
1898	ev_io_stop (loop, iow + i);	2018	ev_io_stop (loop, iow + i);
1899	}	2019	}
1900		2020
1901	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2021	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1902	}	2022	}
1903		2023
1904	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2024	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1905	in the prepare watcher and would dispose of the check watcher.	2025	in the prepare watcher and would dispose of the check watcher.
1906		2026
1907	Method 3: If the module to be embedded supports explicit event	2027	Method 3: If the module to be embedded supports explicit event
1908	notification (adns does), you can also make use of the actual watcher	2028	notification (libadns does), you can also make use of the actual watcher
1909	callbacks, and only destroy/create the watchers in the prepare watcher.	2029	callbacks, and only destroy/create the watchers in the prepare watcher.
1910		2030
1911	static void	2031	static void
1912	timer_cb (EV_P_ ev_timer *w, int revents)	2032	timer_cb (EV_P_ ev_timer *w, int revents)
1913	{	2033	{
1914	adns_state ads = (adns_state)w->data;	2034	adns_state ads = (adns_state)w->data;
1915	update_now (EV_A);	2035	update_now (EV_A);
1916		2036
1917	adns_processtimeouts (ads, &tv_now);	2037	adns_processtimeouts (ads, &tv_now);
1918	}	2038	}
1919		2039
1920	static void	2040	static void
1921	io_cb (EV_P_ ev_io *w, int revents)	2041	io_cb (EV_P_ ev_io *w, int revents)
1922	{	2042	{
1923	adns_state ads = (adns_state)w->data;	2043	adns_state ads = (adns_state)w->data;
1924	update_now (EV_A);	2044	update_now (EV_A);
1925		2045
1926	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2046	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1927	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2047	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1928	}	2048	}
1929		2049
1930	// do not ever call adns_afterpoll	2050	// do not ever call adns_afterpoll
1931		2051
1932	Method 4: Do not use a prepare or check watcher because the module you	2052	Method 4: Do not use a prepare or check watcher because the module you
1933	want to embed is too inflexible to support it. Instead, youc na override	2053	want to embed is too inflexible to support it. Instead, you can override
1934	their poll function. The drawback with this solution is that the main	2054	their poll function. The drawback with this solution is that the main
1935	loop is now no longer controllable by EV. The C<Glib::EV> module does	2055	loop is now no longer controllable by EV. The C<Glib::EV> module does
1936	this.	2056	this.
1937		2057
1938	static gint	2058	static gint
1939	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2059	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1940	{	2060	{
1941	int got_events = 0;	2061	int got_events = 0;
1942		2062
1943	for (n = 0; n < nfds; ++n)	2063	for (n = 0; n < nfds; ++n)
1944	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2064	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1945		2065
1946	if (timeout >= 0)	2066	if (timeout >= 0)
1947	// create/start timer	2067	// create/start timer
1948		2068
1949	// poll	2069	// poll
1950	ev_loop (EV_A_ 0);	2070	ev_loop (EV_A_ 0);
1951		2071
1952	// stop timer again	2072	// stop timer again
1953	if (timeout >= 0)	2073	if (timeout >= 0)
1954	ev_timer_stop (EV_A_ &to);	2074	ev_timer_stop (EV_A_ &to);
1955		2075
1956	// stop io watchers again - their callbacks should have set	2076	// stop io watchers again - their callbacks should have set
1957	for (n = 0; n < nfds; ++n)	2077	for (n = 0; n < nfds; ++n)
1958	ev_io_stop (EV_A_ iow [n]);	2078	ev_io_stop (EV_A_ iow [n]);
1959		2079
1960	return got_events;	2080	return got_events;
1961	}	2081	}
1962		2082
1963		2083
1964	=head2 C<ev_embed> - when one backend isn't enough...	2084	=head2 C<ev_embed> - when one backend isn't enough...
1965		2085
1966	This is a rather advanced watcher type that lets you embed one event loop	2086	This is a rather advanced watcher type that lets you embed one event loop
…		…
2022		2142
2023	Configures the watcher to embed the given loop, which must be	2143	Configures the watcher to embed the given loop, which must be
2024	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	2144	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
2025	invoked automatically, otherwise it is the responsibility of the callback	2145	invoked automatically, otherwise it is the responsibility of the callback
2026	to invoke it (it will continue to be called until the sweep has been done,	2146	to invoke it (it will continue to be called until the sweep has been done,
2027	if you do not want thta, you need to temporarily stop the embed watcher).	2147	if you do not want that, you need to temporarily stop the embed watcher).
2028		2148
2029	=item ev_embed_sweep (loop, ev_embed *)	2149	=item ev_embed_sweep (loop, ev_embed *)
2030		2150
2031	Make a single, non-blocking sweep over the embedded loop. This works	2151	Make a single, non-blocking sweep over the embedded loop. This works
2032	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2152	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2033	apropriate way for embedded loops.	2153	appropriate way for embedded loops.
2034		2154
2035	=item struct ev_loop *other [read-only]	2155	=item struct ev_loop *other [read-only]
2036		2156
2037	The embedded event loop.	2157	The embedded event loop.
2038		2158
…		…
2040		2160
2041	=head3 Examples	2161	=head3 Examples
2042		2162
2043	Example: Try to get an embeddable event loop and embed it into the default	2163	Example: Try to get an embeddable event loop and embed it into the default
2044	event loop. If that is not possible, use the default loop. The default	2164	event loop. If that is not possible, use the default loop. The default
2045	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2165	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2046	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2166	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2047	used).	2167	used).
2048		2168
2049	struct ev_loop *loop_hi = ev_default_init (0);	2169	struct ev_loop *loop_hi = ev_default_init (0);
2050	struct ev_loop *loop_lo = 0;	2170	struct ev_loop *loop_lo = 0;
2051	struct ev_embed embed;	2171	struct ev_embed embed;
2052		2172
2053	// see if there is a chance of getting one that works	2173	// see if there is a chance of getting one that works
2054	// (remember that a flags value of 0 means autodetection)	2174	// (remember that a flags value of 0 means autodetection)
2055	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2175	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2056	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2176	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2057	: 0;	2177	: 0;
2058		2178
2059	// if we got one, then embed it, otherwise default to loop_hi	2179	// if we got one, then embed it, otherwise default to loop_hi
2060	if (loop_lo)	2180	if (loop_lo)
2061	{	2181	{
2062	ev_embed_init (&embed, 0, loop_lo);	2182	ev_embed_init (&embed, 0, loop_lo);
2063	ev_embed_start (loop_hi, &embed);	2183	ev_embed_start (loop_hi, &embed);
2064	}	2184	}
2065	else	2185	else
2066	loop_lo = loop_hi;	2186	loop_lo = loop_hi;
2067		2187
2068	Example: Check if kqueue is available but not recommended and create	2188	Example: Check if kqueue is available but not recommended and create
2069	a kqueue backend for use with sockets (which usually work with any	2189	a kqueue backend for use with sockets (which usually work with any
2070	kqueue implementation). Store the kqueue/socket-only event loop in	2190	kqueue implementation). Store the kqueue/socket-only event loop in
2071	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2191	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2072		2192
2073	struct ev_loop *loop = ev_default_init (0);	2193	struct ev_loop *loop = ev_default_init (0);
2074	struct ev_loop *loop_socket = 0;	2194	struct ev_loop *loop_socket = 0;
2075	struct ev_embed embed;	2195	struct ev_embed embed;
2076		2196
2077	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2197	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2078	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2198	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2079	{	2199	{
2080	ev_embed_init (&embed, 0, loop_socket);	2200	ev_embed_init (&embed, 0, loop_socket);
2081	ev_embed_start (loop, &embed);	2201	ev_embed_start (loop, &embed);
2082	}	2202	}
2083		2203
2084	if (!loop_socket)	2204	if (!loop_socket)
2085	loop_socket = loop;	2205	loop_socket = loop;
2086		2206
2087	// now use loop_socket for all sockets, and loop for everything else	2207	// now use loop_socket for all sockets, and loop for everything else
2088		2208
2089		2209
2090	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2210	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2091		2211
2092	Fork watchers are called when a C<fork ()> was detected (usually because	2212	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2145		2265
2146	=item queueing from a signal handler context	2266	=item queueing from a signal handler context
2147		2267
2148	To implement race-free queueing, you simply add to the queue in the signal	2268	To implement race-free queueing, you simply add to the queue in the signal
2149	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2269	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2150	some fictitiuous SIGUSR1 handler:	2270	some fictitious SIGUSR1 handler:
2151		2271
2152	static ev_async mysig;	2272	static ev_async mysig;
2153		2273
2154	static void	2274	static void
2155	sigusr1_handler (void)	2275	sigusr1_handler (void)
…		…
2229	=item ev_async_send (loop, ev_async *)	2349	=item ev_async_send (loop, ev_async *)
2230		2350
2231	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2351	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2232	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2352	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2233	C<ev_feed_event>, this call is safe to do in other threads, signal or	2353	C<ev_feed_event>, this call is safe to do in other threads, signal or
2234	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2354	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2235	section below on what exactly this means).	2355	section below on what exactly this means).
2236		2356
2237	This call incurs the overhead of a syscall only once per loop iteration,	2357	This call incurs the overhead of a system call only once per loop iteration,
2238	so while the overhead might be noticable, it doesn't apply to repeated	2358	so while the overhead might be noticeable, it doesn't apply to repeated
2239	calls to C<ev_async_send>.	2359	calls to C<ev_async_send>.
		2360
		2361	=item bool = ev_async_pending (ev_async *)
		2362
		2363	Returns a non-zero value when C<ev_async_send> has been called on the
		2364	watcher but the event has not yet been processed (or even noted) by the
		2365	event loop.
		2366
		2367	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
		2368	the loop iterates next and checks for the watcher to have become active,
		2369	it will reset the flag again. C<ev_async_pending> can be used to very
		2370	quickly check whether invoking the loop might be a good idea.
		2371
		2372	Not that this does I<not> check whether the watcher itself is pending, only
		2373	whether it has been requested to make this watcher pending.
2240		2374
2241	=back	2375	=back
2242		2376
2243		2377
2244	=head1 OTHER FUNCTIONS	2378	=head1 OTHER FUNCTIONS
…		…
2255	or timeout without having to allocate/configure/start/stop/free one or	2389	or timeout without having to allocate/configure/start/stop/free one or
2256	more watchers yourself.	2390	more watchers yourself.
2257		2391
2258	If C<fd> is less than 0, then no I/O watcher will be started and events	2392	If C<fd> is less than 0, then no I/O watcher will be started and events
2259	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2393	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2260	C<events> set will be craeted and started.	2394	C<events> set will be created and started.
2261		2395
2262	If C<timeout> is less than 0, then no timeout watcher will be	2396	If C<timeout> is less than 0, then no timeout watcher will be
2263	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2397	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2264	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2398	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2265	dubious value.	2399	dubious value.
…		…
2267	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2401	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2268	passed an C<revents> set like normal event callbacks (a combination of	2402	passed an C<revents> set like normal event callbacks (a combination of
2269	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2403	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2270	value passed to C<ev_once>:	2404	value passed to C<ev_once>:
2271		2405
2272	static void stdin_ready (int revents, void *arg)	2406	static void stdin_ready (int revents, void *arg)
2273	{	2407	{
2274	if (revents & EV_TIMEOUT)	2408	if (revents & EV_TIMEOUT)
2275	/* doh, nothing entered */;	2409	/* doh, nothing entered */;
2276	else if (revents & EV_READ)	2410	else if (revents & EV_READ)
2277	/* stdin might have data for us, joy! */;	2411	/* stdin might have data for us, joy! */;
2278	}	2412	}
2279		2413
2280	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2414	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2281		2415
2282	=item ev_feed_event (ev_loop *, watcher *, int revents)	2416	=item ev_feed_event (ev_loop *, watcher *, int revents)
2283		2417
2284	Feeds the given event set into the event loop, as if the specified event	2418	Feeds the given event set into the event loop, as if the specified event
2285	had happened for the specified watcher (which must be a pointer to an	2419	had happened for the specified watcher (which must be a pointer to an
…		…
2290	Feed an event on the given fd, as if a file descriptor backend detected	2424	Feed an event on the given fd, as if a file descriptor backend detected
2291	the given events it.	2425	the given events it.
2292		2426
2293	=item ev_feed_signal_event (ev_loop *loop, int signum)	2427	=item ev_feed_signal_event (ev_loop *loop, int signum)
2294		2428
2295	Feed an event as if the given signal occured (C<loop> must be the default	2429	Feed an event as if the given signal occurred (C<loop> must be the default
2296	loop!).	2430	loop!).
2297		2431
2298	=back	2432	=back
2299		2433
2300		2434
…		…
2316		2450
2317	=item * Priorities are not currently supported. Initialising priorities	2451	=item * Priorities are not currently supported. Initialising priorities
2318	will fail and all watchers will have the same priority, even though there	2452	will fail and all watchers will have the same priority, even though there
2319	is an ev_pri field.	2453	is an ev_pri field.
2320		2454
		2455	=item * In libevent, the last base created gets the signals, in libev, the
		2456	first base created (== the default loop) gets the signals.
		2457
2321	=item * Other members are not supported.	2458	=item * Other members are not supported.
2322		2459
2323	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2460	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2324	to use the libev header file and library.	2461	to use the libev header file and library.
2325		2462
2326	=back	2463	=back
2327		2464
2328	=head1 C++ SUPPORT	2465	=head1 C++ SUPPORT
2329		2466
2330	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2467	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2331	you to use some convinience methods to start/stop watchers and also change	2468	you to use some convenience methods to start/stop watchers and also change
2332	the callback model to a model using method callbacks on objects.	2469	the callback model to a model using method callbacks on objects.
2333		2470
2334	To use it,	2471	To use it,
2335		2472
2336	#include <ev++.h>	2473	#include <ev++.h>
2337		2474
2338	This automatically includes F<ev.h> and puts all of its definitions (many	2475	This automatically includes F<ev.h> and puts all of its definitions (many
2339	of them macros) into the global namespace. All C++ specific things are	2476	of them macros) into the global namespace. All C++ specific things are
2340	put into the C<ev> namespace. It should support all the same embedding	2477	put into the C<ev> namespace. It should support all the same embedding
2341	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2478	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2408	your compiler is good :), then the method will be fully inlined into the	2545	your compiler is good :), then the method will be fully inlined into the
2409	thunking function, making it as fast as a direct C callback.	2546	thunking function, making it as fast as a direct C callback.
2410		2547
2411	Example: simple class declaration and watcher initialisation	2548	Example: simple class declaration and watcher initialisation
2412		2549
2413	struct myclass	2550	struct myclass
2414	{	2551	{
2415	void io_cb (ev::io &w, int revents) { }	2552	void io_cb (ev::io &w, int revents) { }
2416	}	2553	}
2417		2554
2418	myclass obj;	2555	myclass obj;
2419	ev::io iow;	2556	ev::io iow;
2420	iow.set <myclass, &myclass::io_cb> (&obj);	2557	iow.set <myclass, &myclass::io_cb> (&obj);
2421		2558
2422	=item w->set<function> (void *data = 0)	2559	=item w->set<function> (void *data = 0)
2423		2560
2424	Also sets a callback, but uses a static method or plain function as	2561	Also sets a callback, but uses a static method or plain function as
2425	callback. The optional C<data> argument will be stored in the watcher's	2562	callback. The optional C<data> argument will be stored in the watcher's
…		…
2429		2566
2430	See the method-C<set> above for more details.	2567	See the method-C<set> above for more details.
2431		2568
2432	Example:	2569	Example:
2433		2570
2434	static void io_cb (ev::io &w, int revents) { }	2571	static void io_cb (ev::io &w, int revents) { }
2435	iow.set <io_cb> ();	2572	iow.set <io_cb> ();
2436		2573
2437	=item w->set (struct ev_loop *)	2574	=item w->set (struct ev_loop *)
2438		2575
2439	Associates a different C<struct ev_loop> with this watcher. You can only	2576	Associates a different C<struct ev_loop> with this watcher. You can only
2440	do this when the watcher is inactive (and not pending either).	2577	do this when the watcher is inactive (and not pending either).
2441		2578
2442	=item w->set ([args])	2579	=item w->set ([arguments])
2443		2580
2444	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2581	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2445	called at least once. Unlike the C counterpart, an active watcher gets	2582	called at least once. Unlike the C counterpart, an active watcher gets
2446	automatically stopped and restarted when reconfiguring it with this	2583	automatically stopped and restarted when reconfiguring it with this
2447	method.	2584	method.
2448		2585
2449	=item w->start ()	2586	=item w->start ()
…		…
2473	=back	2610	=back
2474		2611
2475	Example: Define a class with an IO and idle watcher, start one of them in	2612	Example: Define a class with an IO and idle watcher, start one of them in
2476	the constructor.	2613	the constructor.
2477		2614
2478	class myclass	2615	class myclass
2479	{	2616	{
2480	ev::io io; void io_cb (ev::io &w, int revents);	2617	ev::io io; void io_cb (ev::io &w, int revents);
2481	ev:idle idle void idle_cb (ev::idle &w, int revents);	2618	ev:idle idle void idle_cb (ev::idle &w, int revents);
2482		2619
2483	myclass (int fd)	2620	myclass (int fd)
2484	{	2621	{
2485	io .set <myclass, &myclass::io_cb > (this);	2622	io .set <myclass, &myclass::io_cb > (this);
2486	idle.set <myclass, &myclass::idle_cb> (this);	2623	idle.set <myclass, &myclass::idle_cb> (this);
2487		2624
2488	io.start (fd, ev::READ);	2625	io.start (fd, ev::READ);
2489	}	2626	}
2490	};	2627	};
		2628
		2629
		2630	=head1 OTHER LANGUAGE BINDINGS
		2631
		2632	Libev does not offer other language bindings itself, but bindings for a
		2633	number of languages exist in the form of third-party packages. If you know
		2634	any interesting language binding in addition to the ones listed here, drop
		2635	me a note.
		2636
		2637	=over 4
		2638
		2639	=item Perl
		2640
		2641	The EV module implements the full libev API and is actually used to test
		2642	libev. EV is developed together with libev. Apart from the EV core module,
		2643	there are additional modules that implement libev-compatible interfaces
		2644	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
		2645	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
		2646
		2647	It can be found and installed via CPAN, its homepage is at
		2648	L<http://software.schmorp.de/pkg/EV>.
		2649
		2650	=item Python
		2651
		2652	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2653	seems to be quite complete and well-documented. Note, however, that the
		2654	patch they require for libev is outright dangerous as it breaks the ABI
		2655	for everybody else, and therefore, should never be applied in an installed
		2656	libev (if python requires an incompatible ABI then it needs to embed
		2657	libev).
		2658
		2659	=item Ruby
		2660
		2661	Tony Arcieri has written a ruby extension that offers access to a subset
		2662	of the libev API and adds file handle abstractions, asynchronous DNS and
		2663	more on top of it. It can be found via gem servers. Its homepage is at
		2664	L<http://rev.rubyforge.org/>.
		2665
		2666	=item D
		2667
		2668	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
		2669	be found at L<http://proj.llucax.com.ar/wiki/evd>.
		2670
		2671	=back
2491		2672
2492		2673
2493	=head1 MACRO MAGIC	2674	=head1 MACRO MAGIC
2494		2675
2495	Libev can be compiled with a variety of options, the most fundamantal	2676	Libev can be compiled with a variety of options, the most fundamental
2496	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2677	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2497	functions and callbacks have an initial C<struct ev_loop *> argument.	2678	functions and callbacks have an initial C<struct ev_loop *> argument.
2498		2679
2499	To make it easier to write programs that cope with either variant, the	2680	To make it easier to write programs that cope with either variant, the
2500	following macros are defined:	2681	following macros are defined:
…		…
2505		2686
2506	This provides the loop I<argument> for functions, if one is required ("ev	2687	This provides the loop I<argument> for functions, if one is required ("ev
2507	loop argument"). The C<EV_A> form is used when this is the sole argument,	2688	loop argument"). The C<EV_A> form is used when this is the sole argument,
2508	C<EV_A_> is used when other arguments are following. Example:	2689	C<EV_A_> is used when other arguments are following. Example:
2509		2690
2510	ev_unref (EV_A);	2691	ev_unref (EV_A);
2511	ev_timer_add (EV_A_ watcher);	2692	ev_timer_add (EV_A_ watcher);
2512	ev_loop (EV_A_ 0);	2693	ev_loop (EV_A_ 0);
2513		2694
2514	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2695	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2515	which is often provided by the following macro.	2696	which is often provided by the following macro.
2516		2697
2517	=item C<EV_P>, C<EV_P_>	2698	=item C<EV_P>, C<EV_P_>
2518		2699
2519	This provides the loop I<parameter> for functions, if one is required ("ev	2700	This provides the loop I<parameter> for functions, if one is required ("ev
2520	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2701	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2521	C<EV_P_> is used when other parameters are following. Example:	2702	C<EV_P_> is used when other parameters are following. Example:
2522		2703
2523	// this is how ev_unref is being declared	2704	// this is how ev_unref is being declared
2524	static void ev_unref (EV_P);	2705	static void ev_unref (EV_P);
2525		2706
2526	// this is how you can declare your typical callback	2707	// this is how you can declare your typical callback
2527	static void cb (EV_P_ ev_timer *w, int revents)	2708	static void cb (EV_P_ ev_timer *w, int revents)
2528		2709
2529	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2710	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2530	suitable for use with C<EV_A>.	2711	suitable for use with C<EV_A>.
2531		2712
2532	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2713	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2533		2714
2534	Similar to the other two macros, this gives you the value of the default	2715	Similar to the other two macros, this gives you the value of the default
2535	loop, if multiple loops are supported ("ev loop default").	2716	loop, if multiple loops are supported ("ev loop default").
		2717
		2718	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2719
		2720	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2721	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2722	is undefined when the default loop has not been initialised by a previous
		2723	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2724
		2725	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2726	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2536		2727
2537	=back	2728	=back
2538		2729
2539	Example: Declare and initialise a check watcher, utilising the above	2730	Example: Declare and initialise a check watcher, utilising the above
2540	macros so it will work regardless of whether multiple loops are supported	2731	macros so it will work regardless of whether multiple loops are supported
2541	or not.	2732	or not.
2542		2733
2543	static void	2734	static void
2544	check_cb (EV_P_ ev_timer *w, int revents)	2735	check_cb (EV_P_ ev_timer *w, int revents)
2545	{	2736	{
2546	ev_check_stop (EV_A_ w);	2737	ev_check_stop (EV_A_ w);
2547	}	2738	}
2548		2739
2549	ev_check check;	2740	ev_check check;
2550	ev_check_init (&check, check_cb);	2741	ev_check_init (&check, check_cb);
2551	ev_check_start (EV_DEFAULT_ &check);	2742	ev_check_start (EV_DEFAULT_ &check);
2552	ev_loop (EV_DEFAULT_ 0);	2743	ev_loop (EV_DEFAULT_ 0);
2553		2744
2554	=head1 EMBEDDING	2745	=head1 EMBEDDING
2555		2746
2556	Libev can (and often is) directly embedded into host	2747	Libev can (and often is) directly embedded into host
2557	applications. Examples of applications that embed it include the Deliantra	2748	applications. Examples of applications that embed it include the Deliantra
…		…
2564	libev somewhere in your source tree).	2755	libev somewhere in your source tree).
2565		2756
2566	=head2 FILESETS	2757	=head2 FILESETS
2567		2758
2568	Depending on what features you need you need to include one or more sets of files	2759	Depending on what features you need you need to include one or more sets of files
2569	in your app.	2760	in your application.
2570		2761
2571	=head3 CORE EVENT LOOP	2762	=head3 CORE EVENT LOOP
2572		2763
2573	To include only the libev core (all the C<ev_*> functions), with manual	2764	To include only the libev core (all the C<ev_*> functions), with manual
2574	configuration (no autoconf):	2765	configuration (no autoconf):
2575		2766
2576	#define EV_STANDALONE 1	2767	#define EV_STANDALONE 1
2577	#include "ev.c"	2768	#include "ev.c"
2578		2769
2579	This will automatically include F<ev.h>, too, and should be done in a	2770	This will automatically include F<ev.h>, too, and should be done in a
2580	single C source file only to provide the function implementations. To use	2771	single C source file only to provide the function implementations. To use
2581	it, do the same for F<ev.h> in all files wishing to use this API (best	2772	it, do the same for F<ev.h> in all files wishing to use this API (best
2582	done by writing a wrapper around F<ev.h> that you can include instead and	2773	done by writing a wrapper around F<ev.h> that you can include instead and
2583	where you can put other configuration options):	2774	where you can put other configuration options):
2584		2775
2585	#define EV_STANDALONE 1	2776	#define EV_STANDALONE 1
2586	#include "ev.h"	2777	#include "ev.h"
2587		2778
2588	Both header files and implementation files can be compiled with a C++	2779	Both header files and implementation files can be compiled with a C++
2589	compiler (at least, thats a stated goal, and breakage will be treated	2780	compiler (at least, thats a stated goal, and breakage will be treated
2590	as a bug).	2781	as a bug).
2591		2782
2592	You need the following files in your source tree, or in a directory	2783	You need the following files in your source tree, or in a directory
2593	in your include path (e.g. in libev/ when using -Ilibev):	2784	in your include path (e.g. in libev/ when using -Ilibev):
2594		2785
2595	ev.h	2786	ev.h
2596	ev.c	2787	ev.c
2597	ev_vars.h	2788	ev_vars.h
2598	ev_wrap.h	2789	ev_wrap.h
2599		2790
2600	ev_win32.c required on win32 platforms only	2791	ev_win32.c required on win32 platforms only
2601		2792
2602	ev_select.c only when select backend is enabled (which is enabled by default)	2793	ev_select.c only when select backend is enabled (which is enabled by default)
2603	ev_poll.c only when poll backend is enabled (disabled by default)	2794	ev_poll.c only when poll backend is enabled (disabled by default)
2604	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2795	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2605	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2796	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2606	ev_port.c only when the solaris port backend is enabled (disabled by default)	2797	ev_port.c only when the solaris port backend is enabled (disabled by default)
2607		2798
2608	F<ev.c> includes the backend files directly when enabled, so you only need	2799	F<ev.c> includes the backend files directly when enabled, so you only need
2609	to compile this single file.	2800	to compile this single file.
2610		2801
2611	=head3 LIBEVENT COMPATIBILITY API	2802	=head3 LIBEVENT COMPATIBILITY API
2612		2803
2613	To include the libevent compatibility API, also include:	2804	To include the libevent compatibility API, also include:
2614		2805
2615	#include "event.c"	2806	#include "event.c"
2616		2807
2617	in the file including F<ev.c>, and:	2808	in the file including F<ev.c>, and:
2618		2809
2619	#include "event.h"	2810	#include "event.h"
2620		2811
2621	in the files that want to use the libevent API. This also includes F<ev.h>.	2812	in the files that want to use the libevent API. This also includes F<ev.h>.
2622		2813
2623	You need the following additional files for this:	2814	You need the following additional files for this:
2624		2815
2625	event.h	2816	event.h
2626	event.c	2817	event.c
2627		2818
2628	=head3 AUTOCONF SUPPORT	2819	=head3 AUTOCONF SUPPORT
2629		2820
2630	Instead of using C<EV_STANDALONE=1> and providing your config in	2821	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2631	whatever way you want, you can also C<m4_include([libev.m4])> in your	2822	whatever way you want, you can also C<m4_include([libev.m4])> in your
2632	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2823	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2633	include F<config.h> and configure itself accordingly.	2824	include F<config.h> and configure itself accordingly.
2634		2825
2635	For this of course you need the m4 file:	2826	For this of course you need the m4 file:
2636		2827
2637	libev.m4	2828	libev.m4
2638		2829
2639	=head2 PREPROCESSOR SYMBOLS/MACROS	2830	=head2 PREPROCESSOR SYMBOLS/MACROS
2640		2831
2641	Libev can be configured via a variety of preprocessor symbols you have to define	2832	Libev can be configured via a variety of preprocessor symbols you have to
2642	before including any of its files. The default is not to build for multiplicity	2833	define before including any of its files. The default in the absence of
2643	and only include the select backend.	2834	autoconf is noted for every option.
2644		2835
2645	=over 4	2836	=over 4
2646		2837
2647	=item EV_STANDALONE	2838	=item EV_STANDALONE
2648		2839
…		…
2653	F<event.h> that are not directly supported by the libev core alone.	2844	F<event.h> that are not directly supported by the libev core alone.
2654		2845
2655	=item EV_USE_MONOTONIC	2846	=item EV_USE_MONOTONIC
2656		2847
2657	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
2658	monotonic clock option at both compiletime and runtime. Otherwise no use	2849	monotonic clock option at both compile time and runtime. Otherwise no use
2659	of the monotonic clock option will be attempted. If you enable this, you	2850	of the monotonic clock option will be attempted. If you enable this, you
2660	usually have to link against librt or something similar. Enabling it when	2851	usually have to link against librt or something similar. Enabling it when
2661	the functionality isn't available is safe, though, although you have	2852	the functionality isn't available is safe, though, although you have
2662	to make sure you link against any libraries where the C<clock_gettime>	2853	to make sure you link against any libraries where the C<clock_gettime>
2663	function is hiding in (often F<-lrt>).	2854	function is hiding in (often F<-lrt>).
2664		2855
2665	=item EV_USE_REALTIME	2856	=item EV_USE_REALTIME
2666		2857
2667	If defined to be C<1>, libev will try to detect the availability of the	2858	If defined to be C<1>, libev will try to detect the availability of the
2668	realtime clock option at compiletime (and assume its availability at	2859	real-time clock option at compile time (and assume its availability at
2669	runtime if successful). Otherwise no use of the realtime clock option will	2860	runtime if successful). Otherwise no use of the real-time clock option will
2670	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2861	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2671	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2862	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2672	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2863	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2673		2864
2674	=item EV_USE_NANOSLEEP	2865	=item EV_USE_NANOSLEEP
2675		2866
2676	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	2867	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
2677	and will use it for delays. Otherwise it will use C<select ()>.	2868	and will use it for delays. Otherwise it will use C<select ()>.
2678		2869
		2870	=item EV_USE_EVENTFD
		2871
		2872	If defined to be C<1>, then libev will assume that C<eventfd ()> is
		2873	available and will probe for kernel support at runtime. This will improve
		2874	C<ev_signal> and C<ev_async> performance and reduce resource consumption.
		2875	If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
		2876	2.7 or newer, otherwise disabled.
		2877
2679	=item EV_USE_SELECT	2878	=item EV_USE_SELECT
2680		2879
2681	If undefined or defined to be C<1>, libev will compile in support for the	2880	If undefined or defined to be C<1>, libev will compile in support for the
2682	C<select>(2) backend. No attempt at autodetection will be done: if no	2881	C<select>(2) backend. No attempt at auto-detection will be done: if no
2683	other method takes over, select will be it. Otherwise the select backend	2882	other method takes over, select will be it. Otherwise the select backend
2684	will not be compiled in.	2883	will not be compiled in.
2685		2884
2686	=item EV_SELECT_USE_FD_SET	2885	=item EV_SELECT_USE_FD_SET
2687		2886
2688	If defined to C<1>, then the select backend will use the system C<fd_set>	2887	If defined to C<1>, then the select backend will use the system C<fd_set>
2689	structure. This is useful if libev doesn't compile due to a missing	2888	structure. This is useful if libev doesn't compile due to a missing
2690	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2889	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2691	exotic systems. This usually limits the range of file descriptors to some	2890	exotic systems. This usually limits the range of file descriptors to some
2692	low limit such as 1024 or might have other limitations (winsocket only	2891	low limit such as 1024 or might have other limitations (winsocket only
2693	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2892	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2694	influence the size of the C<fd_set> used.	2893	influence the size of the C<fd_set> used.
2695		2894
…		…
2719		2918
2720	=item EV_USE_EPOLL	2919	=item EV_USE_EPOLL
2721		2920
2722	If defined to be C<1>, libev will compile in support for the Linux	2921	If defined to be C<1>, libev will compile in support for the Linux
2723	C<epoll>(7) backend. Its availability will be detected at runtime,	2922	C<epoll>(7) backend. Its availability will be detected at runtime,
2724	otherwise another method will be used as fallback. This is the	2923	otherwise another method will be used as fallback. This is the preferred
2725	preferred backend for GNU/Linux systems.	2924	backend for GNU/Linux systems. If undefined, it will be enabled if the
		2925	headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2726		2926
2727	=item EV_USE_KQUEUE	2927	=item EV_USE_KQUEUE
2728		2928
2729	If defined to be C<1>, libev will compile in support for the BSD style	2929	If defined to be C<1>, libev will compile in support for the BSD style
2730	C<kqueue>(2) backend. Its actual availability will be detected at runtime,	2930	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
…		…
2743	otherwise another method will be used as fallback. This is the preferred	2943	otherwise another method will be used as fallback. This is the preferred
2744	backend for Solaris 10 systems.	2944	backend for Solaris 10 systems.
2745		2945
2746	=item EV_USE_DEVPOLL	2946	=item EV_USE_DEVPOLL
2747		2947
2748	reserved for future expansion, works like the USE symbols above.	2948	Reserved for future expansion, works like the USE symbols above.
2749		2949
2750	=item EV_USE_INOTIFY	2950	=item EV_USE_INOTIFY
2751		2951
2752	If defined to be C<1>, libev will compile in support for the Linux inotify	2952	If defined to be C<1>, libev will compile in support for the Linux inotify
2753	interface to speed up C<ev_stat> watchers. Its actual availability will	2953	interface to speed up C<ev_stat> watchers. Its actual availability will
2754	be detected at runtime.	2954	be detected at runtime. If undefined, it will be enabled if the headers
		2955	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2755		2956
2756	=item EV_ATOMIC_T	2957	=item EV_ATOMIC_T
2757		2958
2758	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	2959	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
2759	access is atomic with respect to other threads or signal contexts. No such	2960	access is atomic with respect to other threads or signal contexts. No such
2760	type is easily found in the C language, so you can provide your own type	2961	type is easily found in the C language, so you can provide your own type
2761	that you know is safe for your purposes. It is used both for signal handler "locking"	2962	that you know is safe for your purposes. It is used both for signal handler "locking"
2762	as well as for signal and thread safety in C<ev_async> watchers.	2963	as well as for signal and thread safety in C<ev_async> watchers.
2763		2964
2764	In the absense of this define, libev will use C<sig_atomic_t volatile>	2965	In the absence of this define, libev will use C<sig_atomic_t volatile>
2765	(from F<signal.h>), which is usually good enough on most platforms.	2966	(from F<signal.h>), which is usually good enough on most platforms.
2766		2967
2767	=item EV_H	2968	=item EV_H
2768		2969
2769	The name of the F<ev.h> header file used to include it. The default if	2970	The name of the F<ev.h> header file used to include it. The default if
…		…
2808	When doing priority-based operations, libev usually has to linearly search	3009	When doing priority-based operations, libev usually has to linearly search
2809	all the priorities, so having many of them (hundreds) uses a lot of space	3010	all the priorities, so having many of them (hundreds) uses a lot of space
2810	and time, so using the defaults of five priorities (-2 .. +2) is usually	3011	and time, so using the defaults of five priorities (-2 .. +2) is usually
2811	fine.	3012	fine.
2812		3013
2813	If your embedding app does not need any priorities, defining these both to	3014	If your embedding application does not need any priorities, defining these both to
2814	C<0> will save some memory and cpu.	3015	C<0> will save some memory and CPU.
2815		3016
2816	=item EV_PERIODIC_ENABLE	3017	=item EV_PERIODIC_ENABLE
2817		3018
2818	If undefined or defined to be C<1>, then periodic timers are supported. If	3019	If undefined or defined to be C<1>, then periodic timers are supported. If
2819	defined to be C<0>, then they are not. Disabling them saves a few kB of	3020	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2846	defined to be C<0>, then they are not.	3047	defined to be C<0>, then they are not.
2847		3048
2848	=item EV_MINIMAL	3049	=item EV_MINIMAL
2849		3050
2850	If you need to shave off some kilobytes of code at the expense of some	3051	If you need to shave off some kilobytes of code at the expense of some
2851	speed, define this symbol to C<1>. Currently only used for gcc to override	3052	speed, define this symbol to C<1>. Currently this is used to override some
2852	some inlining decisions, saves roughly 30% codesize of amd64.	3053	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3054	much smaller 2-heap for timer management over the default 4-heap.
2853		3055
2854	=item EV_PID_HASHSIZE	3056	=item EV_PID_HASHSIZE
2855		3057
2856	C<ev_child> watchers use a small hash table to distribute workload by	3058	C<ev_child> watchers use a small hash table to distribute workload by
2857	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3059	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2864	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3066	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2865	usually more than enough. If you need to manage thousands of C<ev_stat>	3067	usually more than enough. If you need to manage thousands of C<ev_stat>
2866	watchers you might want to increase this value (I<must> be a power of	3068	watchers you might want to increase this value (I<must> be a power of
2867	two).	3069	two).
2868		3070
		3071	=item EV_USE_4HEAP
		3072
		3073	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3074	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3075	to C<1>. The 4-heap uses more complicated (longer) code but has
		3076	noticeably faster performance with many (thousands) of watchers.
		3077
		3078	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3079	(disabled).
		3080
		3081	=item EV_HEAP_CACHE_AT
		3082
		3083	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3084	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3085	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3086	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3087	but avoids random read accesses on heap changes. This improves performance
		3088	noticeably with with many (hundreds) of watchers.
		3089
		3090	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3091	(disabled).
		3092
		3093	=item EV_VERIFY
		3094
		3095	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3096	be done: If set to C<0>, no internal verification code will be compiled
		3097	in. If set to C<1>, then verification code will be compiled in, but not
		3098	called. If set to C<2>, then the internal verification code will be
		3099	called once per loop, which can slow down libev. If set to C<3>, then the
		3100	verification code will be called very frequently, which will slow down
		3101	libev considerably.
		3102
		3103	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3104	C<0.>
		3105
2869	=item EV_COMMON	3106	=item EV_COMMON
2870		3107
2871	By default, all watchers have a C<void *data> member. By redefining	3108	By default, all watchers have a C<void *data> member. By redefining
2872	this macro to a something else you can include more and other types of	3109	this macro to a something else you can include more and other types of
2873	members. You have to define it each time you include one of the files,	3110	members. You have to define it each time you include one of the files,
2874	though, and it must be identical each time.	3111	though, and it must be identical each time.
2875		3112
2876	For example, the perl EV module uses something like this:	3113	For example, the perl EV module uses something like this:
2877		3114
2878	#define EV_COMMON \	3115	#define EV_COMMON \
2879	SV *self; /* contains this struct */ \	3116	SV *self; /* contains this struct */ \
2880	SV *cb_sv, *fh /* note no trailing ";" */	3117	SV *cb_sv, *fh /* note no trailing ";" */
2881		3118
2882	=item EV_CB_DECLARE (type)	3119	=item EV_CB_DECLARE (type)
2883		3120
2884	=item EV_CB_INVOKE (watcher, revents)	3121	=item EV_CB_INVOKE (watcher, revents)
2885		3122
…		…
2892	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3129	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2893	method calls instead of plain function calls in C++.	3130	method calls instead of plain function calls in C++.
2894		3131
2895	=head2 EXPORTED API SYMBOLS	3132	=head2 EXPORTED API SYMBOLS
2896		3133
2897	If you need to re-export the API (e.g. via a dll) and you need a list of	3134	If you need to re-export the API (e.g. via a DLL) and you need a list of
2898	exported symbols, you can use the provided F<Symbol.*> files which list	3135	exported symbols, you can use the provided F<Symbol.*> files which list
2899	all public symbols, one per line:	3136	all public symbols, one per line:
2900		3137
2901	Symbols.ev for libev proper	3138	Symbols.ev for libev proper
2902	Symbols.event for the libevent emulation	3139	Symbols.event for the libevent emulation
2903		3140
2904	This can also be used to rename all public symbols to avoid clashes with	3141	This can also be used to rename all public symbols to avoid clashes with
2905	multiple versions of libev linked together (which is obviously bad in	3142	multiple versions of libev linked together (which is obviously bad in
2906	itself, but sometimes it is inconvinient to avoid this).	3143	itself, but sometimes it is inconvenient to avoid this).
2907		3144
2908	A sed command like this will create wrapper C<#define>'s that you need to	3145	A sed command like this will create wrapper C<#define>'s that you need to
2909	include before including F<ev.h>:	3146	include before including F<ev.h>:
2910		3147
2911	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3148	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
2928	file.	3165	file.
2929		3166
2930	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3167	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2931	that everybody includes and which overrides some configure choices:	3168	that everybody includes and which overrides some configure choices:
2932		3169
2933	#define EV_MINIMAL 1	3170	#define EV_MINIMAL 1
2934	#define EV_USE_POLL 0	3171	#define EV_USE_POLL 0
2935	#define EV_MULTIPLICITY 0	3172	#define EV_MULTIPLICITY 0
2936	#define EV_PERIODIC_ENABLE 0	3173	#define EV_PERIODIC_ENABLE 0
2937	#define EV_STAT_ENABLE 0	3174	#define EV_STAT_ENABLE 0
2938	#define EV_FORK_ENABLE 0	3175	#define EV_FORK_ENABLE 0
2939	#define EV_CONFIG_H <config.h>	3176	#define EV_CONFIG_H <config.h>
2940	#define EV_MINPRI 0	3177	#define EV_MINPRI 0
2941	#define EV_MAXPRI 0	3178	#define EV_MAXPRI 0
2942		3179
2943	#include "ev++.h"	3180	#include "ev++.h"
2944		3181
2945	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3182	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2946		3183
2947	#include "ev_cpp.h"	3184	#include "ev_cpp.h"
2948	#include "ev.c"	3185	#include "ev.c"
		3186
		3187
		3188	=head1 THREADS AND COROUTINES
		3189
		3190	=head2 THREADS
		3191
		3192	Libev itself is completely thread-safe, but it uses no locking. This
		3193	means that you can use as many loops as you want in parallel, as long as
		3194	only one thread ever calls into one libev function with the same loop
		3195	parameter.
		3196
		3197	Or put differently: calls with different loop parameters can be done in
		3198	parallel from multiple threads, calls with the same loop parameter must be
		3199	done serially (but can be done from different threads, as long as only one
		3200	thread ever is inside a call at any point in time, e.g. by using a mutex
		3201	per loop).
		3202
		3203	If you want to know which design (one loop, locking, or multiple loops
		3204	without or something else still) is best for your problem, then I cannot
		3205	help you. I can give some generic advice however:
		3206
		3207	=over 4
		3208
		3209	=item * most applications have a main thread: use the default libev loop
		3210	in that thread, or create a separate thread running only the default loop.
		3211
		3212	This helps integrating other libraries or software modules that use libev
		3213	themselves and don't care/know about threading.
		3214
		3215	=item * one loop per thread is usually a good model.
		3216
		3217	Doing this is almost never wrong, sometimes a better-performance model
		3218	exists, but it is always a good start.
		3219
		3220	=item * other models exist, such as the leader/follower pattern, where one
		3221	loop is handed through multiple threads in a kind of round-robin fashion.
		3222
		3223	Choosing a model is hard - look around, learn, know that usually you can do
		3224	better than you currently do :-)
		3225
		3226	=item * often you need to talk to some other thread which blocks in the
		3227	event loop - C<ev_async> watchers can be used to wake them up from other
		3228	threads safely (or from signal contexts...).
		3229
		3230	=back
		3231
		3232	=head2 COROUTINES
		3233
		3234	Libev is much more accommodating to coroutines ("cooperative threads"):
		3235	libev fully supports nesting calls to it's functions from different
		3236	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3237	different coroutines and switch freely between both coroutines running the
		3238	loop, as long as you don't confuse yourself). The only exception is that
		3239	you must not do this from C<ev_periodic> reschedule callbacks.
		3240
		3241	Care has been invested into making sure that libev does not keep local
		3242	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3243	switches.
2949		3244
2950		3245
2951	=head1 COMPLEXITIES	3246	=head1 COMPLEXITIES
2952		3247
2953	In this section the complexities of (many of) the algorithms used inside	3248	In this section the complexities of (many of) the algorithms used inside
…		…
2985	correct watcher to remove. The lists are usually short (you don't usually	3280	correct watcher to remove. The lists are usually short (you don't usually
2986	have many watchers waiting for the same fd or signal).	3281	have many watchers waiting for the same fd or signal).
2987		3282
2988	=item Finding the next timer in each loop iteration: O(1)	3283	=item Finding the next timer in each loop iteration: O(1)
2989		3284
2990	By virtue of using a binary heap, the next timer is always found at the	3285	By virtue of using a binary or 4-heap, the next timer is always found at a
2991	beginning of the storage array.	3286	fixed position in the storage array.
2992		3287
2993	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3288	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2994		3289
2995	A change means an I/O watcher gets started or stopped, which requires	3290	A change means an I/O watcher gets started or stopped, which requires
2996	libev to recalculate its status (and possibly tell the kernel, depending	3291	libev to recalculate its status (and possibly tell the kernel, depending
2997	on backend and wether C<ev_io_set> was used).	3292	on backend and whether C<ev_io_set> was used).
2998		3293
2999	=item Activating one watcher (putting it into the pending state): O(1)	3294	=item Activating one watcher (putting it into the pending state): O(1)
3000		3295
3001	=item Priority handling: O(number_of_priorities)	3296	=item Priority handling: O(number_of_priorities)
3002		3297
…		…
3009		3304
3010	=item Processing ev_async_send: O(number_of_async_watchers)	3305	=item Processing ev_async_send: O(number_of_async_watchers)
3011		3306
3012	=item Processing signals: O(max_signal_number)	3307	=item Processing signals: O(max_signal_number)
3013		3308
3014	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3309	Sending involves a system call I<iff> there were no other C<ev_async_send>
3015	calls in the current loop iteration. Checking for async and signal events	3310	calls in the current loop iteration. Checking for async and signal events
3016	involves iterating over all running async watchers or all signal numbers.	3311	involves iterating over all running async watchers or all signal numbers.
3017		3312
3018	=back	3313	=back
3019		3314
3020		3315
3021	=head1 Win32 platform limitations and workarounds	3316	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3022		3317
3023	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3318	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3024	requires, and its I/O model is fundamentally incompatible with the POSIX	3319	requires, and its I/O model is fundamentally incompatible with the POSIX
3025	model. Libev still offers limited functionality on this platform in	3320	model. Libev still offers limited functionality on this platform in
3026	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3321	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3027	descriptors. This only applies when using Win32 natively, not when using	3322	descriptors. This only applies when using Win32 natively, not when using
3028	e.g. cygwin.	3323	e.g. cygwin.
3029		3324
		3325	Lifting these limitations would basically require the full
		3326	re-implementation of the I/O system. If you are into these kinds of
		3327	things, then note that glib does exactly that for you in a very portable
		3328	way (note also that glib is the slowest event library known to man).
		3329
3030	There is no supported compilation method available on windows except	3330	There is no supported compilation method available on windows except
3031	embedding it into other applications.	3331	embedding it into other applications.
3032		3332
		3333	Not a libev limitation but worth mentioning: windows apparently doesn't
		3334	accept large writes: instead of resulting in a partial write, windows will
		3335	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3336	so make sure you only write small amounts into your sockets (less than a
		3337	megabyte seems safe, but thsi apparently depends on the amount of memory
		3338	available).
		3339
3033	Due to the many, low, and arbitrary limits on the win32 platform and the	3340	Due to the many, low, and arbitrary limits on the win32 platform and
3034	abysmal performance of winsockets, using a large number of sockets is not	3341	the abysmal performance of winsockets, using a large number of sockets
3035	recommended (and not reasonable). If your program needs to use more than	3342	is not recommended (and not reasonable). If your program needs to use
3036	a hundred or so sockets, then likely it needs to use a totally different	3343	more than a hundred or so sockets, then likely it needs to use a totally
3037	implementation for windows, as libev offers the POSIX model, which cannot	3344	different implementation for windows, as libev offers the POSIX readiness
3038	be implemented efficiently on windows (microsoft monopoly games).	3345	notification model, which cannot be implemented efficiently on windows
		3346	(Microsoft monopoly games).
		3347
		3348	A typical way to use libev under windows is to embed it (see the embedding
		3349	section for details) and use the following F<evwrap.h> header file instead
		3350	of F<ev.h>:
		3351
		3352	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3353	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3354
		3355	#include "ev.h"
		3356
		3357	And compile the following F<evwrap.c> file into your project (make sure
		3358	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3359
		3360	#include "evwrap.h"
		3361	#include "ev.c"
3039		3362
3040	=over 4	3363	=over 4
3041		3364
3042	=item The winsocket select function	3365	=item The winsocket select function
3043		3366
3044	The winsocket C<select> function doesn't follow POSIX in that it requires	3367	The winsocket C<select> function doesn't follow POSIX in that it
3045	socket I<handles> and not socket I<file descriptors>. This makes select	3368	requires socket I<handles> and not socket I<file descriptors> (it is
3046	very inefficient, and also requires a mapping from file descriptors	3369	also extremely buggy). This makes select very inefficient, and also
3047	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3370	requires a mapping from file descriptors to socket handles (the Microsoft
3048	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3371	C runtime provides the function C<_open_osfhandle> for this). See the
3049	symbols for more info.	3372	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3373	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3050		3374
3051	The configuration for a "naked" win32 using the microsoft runtime	3375	The configuration for a "naked" win32 using the Microsoft runtime
3052	libraries and raw winsocket select is:	3376	libraries and raw winsocket select is:
3053		3377
3054	#define EV_USE_SELECT 1	3378	#define EV_USE_SELECT 1
3055	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3379	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3056		3380
3057	Note that winsockets handling of fd sets is O(n), so you can easily get a	3381	Note that winsockets handling of fd sets is O(n), so you can easily get a
3058	complexity in the O(n²) range when using win32.	3382	complexity in the O(n²) range when using win32.
3059		3383
3060	=item Limited number of file descriptors	3384	=item Limited number of file descriptors
3061		3385
3062	Windows has numerous arbitrary (and low) limits on things. Early versions	3386	Windows has numerous arbitrary (and low) limits on things.
3063	of winsocket's select only supported waiting for a max. of C<64> handles	3387
		3388	Early versions of winsocket's select only supported waiting for a maximum
3064	(probably owning to the fact that all windows kernels can only wait for	3389	of C<64> handles (probably owning to the fact that all windows kernels
3065	C<64> things at the same time internally; microsoft recommends spawning a	3390	can only wait for C<64> things at the same time internally; Microsoft
3066	chain of threads and wait for 63 handles and the previous thread in each).	3391	recommends spawning a chain of threads and wait for 63 handles and the
		3392	previous thread in each. Great).
3067		3393
3068	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3394	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3069	to some high number (e.g. C<2048>) before compiling the winsocket select	3395	to some high number (e.g. C<2048>) before compiling the winsocket select
3070	call (which might be in libev or elsewhere, for example, perl does its own	3396	call (which might be in libev or elsewhere, for example, perl does its own
3071	select emulation on windows).	3397	select emulation on windows).
3072		3398
3073	Another limit is the number of file descriptors in the microsoft runtime	3399	Another limit is the number of file descriptors in the Microsoft runtime
3074	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3400	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3075	or something like this inside microsoft). You can increase this by calling	3401	or something like this inside Microsoft). You can increase this by calling
3076	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3402	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3077	arbitrary limit), but is broken in many versions of the microsoft runtime	3403	arbitrary limit), but is broken in many versions of the Microsoft runtime
3078	libraries.	3404	libraries.
3079		3405
3080	This might get you to about C<512> or C<2048> sockets (depending on	3406	This might get you to about C<512> or C<2048> sockets (depending on
3081	windows version and/or the phase of the moon). To get more, you need to	3407	windows version and/or the phase of the moon). To get more, you need to
3082	wrap all I/O functions and provide your own fd management, but the cost of	3408	wrap all I/O functions and provide your own fd management, but the cost of
3083	calling select (O(n²)) will likely make this unworkable.	3409	calling select (O(n²)) will likely make this unworkable.
3084		3410
3085	=back	3411	=back
3086		3412
3087		3413
		3414	=head1 PORTABILITY REQUIREMENTS
		3415
		3416	In addition to a working ISO-C implementation, libev relies on a few
		3417	additional extensions:
		3418
		3419	=over 4
		3420
		3421	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3422	calling conventions regardless of C<ev_watcher_type *>.
		3423
		3424	Libev assumes not only that all watcher pointers have the same internal
		3425	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3426	assumes that the same (machine) code can be used to call any watcher
		3427	callback: The watcher callbacks have different type signatures, but libev
		3428	calls them using an C<ev_watcher *> internally.
		3429
		3430	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3431
		3432	The type C<sig_atomic_t volatile> (or whatever is defined as
		3433	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3434	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3435	believed to be sufficiently portable.
		3436
		3437	=item C<sigprocmask> must work in a threaded environment
		3438
		3439	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3440	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3441	pthread implementations will either allow C<sigprocmask> in the "main
		3442	thread" or will block signals process-wide, both behaviours would
		3443	be compatible with libev. Interaction between C<sigprocmask> and
		3444	C<pthread_sigmask> could complicate things, however.
		3445
		3446	The most portable way to handle signals is to block signals in all threads
		3447	except the initial one, and run the default loop in the initial thread as
		3448	well.
		3449
		3450	=item C<long> must be large enough for common memory allocation sizes
		3451
		3452	To improve portability and simplify using libev, libev uses C<long>
		3453	internally instead of C<size_t> when allocating its data structures. On
		3454	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3455	is still at least 31 bits everywhere, which is enough for hundreds of
		3456	millions of watchers.
		3457
		3458	=item C<double> must hold a time value in seconds with enough accuracy
		3459
		3460	The type C<double> is used to represent timestamps. It is required to
		3461	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3462	enough for at least into the year 4000. This requirement is fulfilled by
		3463	implementations implementing IEEE 754 (basically all existing ones).
		3464
		3465	=back
		3466
		3467	If you know of other additional requirements drop me a note.
		3468
		3469
		3470	=head1 COMPILER WARNINGS
		3471
		3472	Depending on your compiler and compiler settings, you might get no or a
		3473	lot of warnings when compiling libev code. Some people are apparently
		3474	scared by this.
		3475
		3476	However, these are unavoidable for many reasons. For one, each compiler
		3477	has different warnings, and each user has different tastes regarding
		3478	warning options. "Warn-free" code therefore cannot be a goal except when
		3479	targeting a specific compiler and compiler-version.
		3480
		3481	Another reason is that some compiler warnings require elaborate
		3482	workarounds, or other changes to the code that make it less clear and less
		3483	maintainable.
		3484
		3485	And of course, some compiler warnings are just plain stupid, or simply
		3486	wrong (because they don't actually warn about the condition their message
		3487	seems to warn about).
		3488
		3489	While libev is written to generate as few warnings as possible,
		3490	"warn-free" code is not a goal, and it is recommended not to build libev
		3491	with any compiler warnings enabled unless you are prepared to cope with
		3492	them (e.g. by ignoring them). Remember that warnings are just that:
		3493	warnings, not errors, or proof of bugs.
		3494
		3495
		3496	=head1 VALGRIND
		3497
		3498	Valgrind has a special section here because it is a popular tool that is
		3499	highly useful, but valgrind reports are very hard to interpret.
		3500
		3501	If you think you found a bug (memory leak, uninitialised data access etc.)
		3502	in libev, then check twice: If valgrind reports something like:
		3503
		3504	==2274== definitely lost: 0 bytes in 0 blocks.
		3505	==2274== possibly lost: 0 bytes in 0 blocks.
		3506	==2274== still reachable: 256 bytes in 1 blocks.
		3507
		3508	Then there is no memory leak. Similarly, under some circumstances,
		3509	valgrind might report kernel bugs as if it were a bug in libev, or it
		3510	might be confused (it is a very good tool, but only a tool).
		3511
		3512	If you are unsure about something, feel free to contact the mailing list
		3513	with the full valgrind report and an explanation on why you think this is
		3514	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3515	no bug" answer and take the chance of learning how to interpret valgrind
		3516	properly.
		3517
		3518	If you need, for some reason, empty reports from valgrind for your project
		3519	I suggest using suppression lists.
		3520
		3521
3088	=head1 AUTHOR	3522	=head1 AUTHOR
3089		3523
3090	Marc Lehmann <libev@schmorp.de>.	3524	Marc Lehmann <libev@schmorp.de>.
3091		3525

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