ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.159 by root, Thu May 22 02:44:57 2008 UTC vs.
Revision 1.229 by root, Wed Apr 15 17:49:27 2009 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	// a single header file is required
12	#include <ev.h>	12	#include <ev.h>
13		13
		14	#include <stdio.h> // for puts
		15
14	// every watcher type has its own typedef'd struct	16	// every watcher type has its own typedef'd struct
15	// with the name ev_<type>	17	// with the name ev_TYPE
16	ev_io stdin_watcher;	18	ev_io stdin_watcher;
17	ev_timer timeout_watcher;	19	ev_timer timeout_watcher;
18		20
19	// all watcher callbacks have a similar signature	21	// all watcher callbacks have a similar signature
20	// this callback is called when data is readable on stdin	22	// this callback is called when data is readable on stdin
21	static void	23	static void
22	stdin_cb (EV_P_ struct ev_io *w, int revents)	24	stdin_cb (EV_P_ ev_io *w, int revents)
23	{	25	{
24	puts ("stdin ready");	26	puts ("stdin ready");
25	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
26	// with its corresponding stop function.	28	// with its corresponding stop function.
27	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
28		30
29	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_loop's to stop iterating
30	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_unloop (EV_A_ EVUNLOOP_ALL);
31	}	33	}
32		34
33	// another callback, this time for a time-out	35	// another callback, this time for a time-out
34	static void	36	static void
35	timeout_cb (EV_P_ struct ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
36	{	38	{
37	puts ("timeout");	39	puts ("timeout");
38	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_loop to stop iterating
39	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_unloop (EV_A_ EVUNLOOP_ONE);
40	}	42	}
41		43
42	int	44	int
43	main (void)	45	main (void)
44	{	46	{
45	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
46	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = ev_default_loop (0);
47		49
48	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
49	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
51	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
52		54
53	// initialise a timer watcher, then start it	55	// initialise a timer watcher, then start it
54	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
56	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
57		59
58	// now wait for events to arrive	60	// now wait for events to arrive
59	ev_loop (loop, 0);	61	ev_loop (loop, 0);
60		62
61	// unloop was called, so exit	63	// unloop was called, so exit
62	return 0;	64	return 0;
63	}	65	}
64		66
65	=head1 DESCRIPTION	67	=head1 DESCRIPTION
66		68
67	The newest version of this document is also available as an html-formatted	69	The newest version of this document is also available as an html-formatted
68	web page you might find easier to navigate when reading it for the first	70	web page you might find easier to navigate when reading it for the first
…		…
103	Libev is very configurable. In this manual the default (and most common)	105	Libev is very configurable. In this manual the default (and most common)
104	configuration will be described, which supports multiple event loops. For	106	configuration will be described, which supports multiple event loops. For
105	more info about various configuration options please have a look at	107	more info about various configuration options please have a look at
106	B<EMBED> section in this manual. If libev was configured without support	108	B<EMBED> section in this manual. If libev was configured without support
107	for multiple event loops, then all functions taking an initial argument of	109	for multiple event loops, then all functions taking an initial argument of
108	name C<loop> (which is always of type C<struct ev_loop *>) will not have	110	name C<loop> (which is always of type C<ev_loop *>) will not have
109	this argument.	111	this argument.
110		112
111	=head2 TIME REPRESENTATION	113	=head2 TIME REPRESENTATION
112		114
113	Libev represents time as a single floating point number, representing the	115	Libev represents time as a single floating point number, representing the
114	(fractional) number of seconds since the (POSIX) epoch (somewhere near	116	(fractional) number of seconds since the (POSIX) epoch (somewhere near
115	the beginning of 1970, details are complicated, don't ask). This type is	117	the beginning of 1970, details are complicated, don't ask). This type is
116	called C<ev_tstamp>, which is what you should use too. It usually aliases	118	called C<ev_tstamp>, which is what you should use too. It usually aliases
117	to the C<double> type in C, and when you need to do any calculations on	119	to the C<double> type in C, and when you need to do any calculations on
118	it, you should treat it as some floatingpoint value. Unlike the name	120	it, you should treat it as some floating point value. Unlike the name
119	component C<stamp> might indicate, it is also used for time differences	121	component C<stamp> might indicate, it is also used for time differences
120	throughout libev.	122	throughout libev.
		123
		124	=head1 ERROR HANDLING
		125
		126	Libev knows three classes of errors: operating system errors, usage errors
		127	and internal errors (bugs).
		128
		129	When libev catches an operating system error it cannot handle (for example
		130	a system call indicating a condition libev cannot fix), it calls the callback
		131	set via C<ev_set_syserr_cb>, which is supposed to fix the problem or
		132	abort. The default is to print a diagnostic message and to call C<abort
		133	()>.
		134
		135	When libev detects a usage error such as a negative timer interval, then
		136	it will print a diagnostic message and abort (via the C<assert> mechanism,
		137	so C<NDEBUG> will disable this checking): these are programming errors in
		138	the libev caller and need to be fixed there.
		139
		140	Libev also has a few internal error-checking C<assert>ions, and also has
		141	extensive consistency checking code. These do not trigger under normal
		142	circumstances, as they indicate either a bug in libev or worse.
		143
121		144
122	=head1 GLOBAL FUNCTIONS	145	=head1 GLOBAL FUNCTIONS
123		146
124	These functions can be called anytime, even before initialising the	147	These functions can be called anytime, even before initialising the
125	library in any way.	148	library in any way.
…		…
134		157
135	=item ev_sleep (ev_tstamp interval)	158	=item ev_sleep (ev_tstamp interval)
136		159
137	Sleep for the given interval: The current thread will be blocked until	160	Sleep for the given interval: The current thread will be blocked until
138	either it is interrupted or the given time interval has passed. Basically	161	either it is interrupted or the given time interval has passed. Basically
139	this is a subsecond-resolution C<sleep ()>.	162	this is a sub-second-resolution C<sleep ()>.
140		163
141	=item int ev_version_major ()	164	=item int ev_version_major ()
142		165
143	=item int ev_version_minor ()	166	=item int ev_version_minor ()
144		167
…		…
157	not a problem.	180	not a problem.
158		181
159	Example: Make sure we haven't accidentally been linked against the wrong	182	Example: Make sure we haven't accidentally been linked against the wrong
160	version.	183	version.
161		184
162	assert (("libev version mismatch",	185	assert (("libev version mismatch",
163	ev_version_major () == EV_VERSION_MAJOR	186	ev_version_major () == EV_VERSION_MAJOR
164	&& ev_version_minor () >= EV_VERSION_MINOR));	187	&& ev_version_minor () >= EV_VERSION_MINOR));
165		188
166	=item unsigned int ev_supported_backends ()	189	=item unsigned int ev_supported_backends ()
167		190
168	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>	191	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>
169	value) compiled into this binary of libev (independent of their	192	value) compiled into this binary of libev (independent of their
…		…
171	a description of the set values.	194	a description of the set values.
172		195
173	Example: make sure we have the epoll method, because yeah this is cool and	196	Example: make sure we have the epoll method, because yeah this is cool and
174	a must have and can we have a torrent of it please!!!11	197	a must have and can we have a torrent of it please!!!11
175		198
176	assert (("sorry, no epoll, no sex",	199	assert (("sorry, no epoll, no sex",
177	ev_supported_backends () & EVBACKEND_EPOLL));	200	ev_supported_backends () & EVBACKEND_EPOLL));
178		201
179	=item unsigned int ev_recommended_backends ()	202	=item unsigned int ev_recommended_backends ()
180		203
181	Return the set of all backends compiled into this binary of libev and also	204	Return the set of all backends compiled into this binary of libev and also
182	recommended for this platform. This set is often smaller than the one	205	recommended for this platform. This set is often smaller than the one
183	returned by C<ev_supported_backends>, as for example kqueue is broken on	206	returned by C<ev_supported_backends>, as for example kqueue is broken on
184	most BSDs and will not be autodetected unless you explicitly request it	207	most BSDs and will not be auto-detected unless you explicitly request it
185	(assuming you know what you are doing). This is the set of backends that	208	(assuming you know what you are doing). This is the set of backends that
186	libev will probe for if you specify no backends explicitly.	209	libev will probe for if you specify no backends explicitly.
187		210
188	=item unsigned int ev_embeddable_backends ()	211	=item unsigned int ev_embeddable_backends ()
189		212
…		…
193	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	216	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
194	recommended ones.	217	recommended ones.
195		218
196	See the description of C<ev_embed> watchers for more info.	219	See the description of C<ev_embed> watchers for more info.
197		220
198	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	221	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]
199		222
200	Sets the allocation function to use (the prototype is similar - the	223	Sets the allocation function to use (the prototype is similar - the
201	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	224	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
202	used to allocate and free memory (no surprises here). If it returns zero	225	used to allocate and free memory (no surprises here). If it returns zero
203	when memory needs to be allocated (C<size != 0>), the library might abort	226	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
229	}	252	}
230		253
231	...	254	...
232	ev_set_allocator (persistent_realloc);	255	ev_set_allocator (persistent_realloc);
233		256
234	=item ev_set_syserr_cb (void (*cb)(const char *msg));	257	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]
235		258
236	Set the callback function to call on a retryable syscall error (such	259	Set the callback function to call on a retryable system call error (such
237	as failed select, poll, epoll_wait). The message is a printable string	260	as failed select, poll, epoll_wait). The message is a printable string
238	indicating the system call or subsystem causing the problem. If this	261	indicating the system call or subsystem causing the problem. If this
239	callback is set, then libev will expect it to remedy the sitution, no	262	callback is set, then libev will expect it to remedy the situation, no
240	matter what, when it returns. That is, libev will generally retry the	263	matter what, when it returns. That is, libev will generally retry the
241	requested operation, or, if the condition doesn't go away, do bad stuff	264	requested operation, or, if the condition doesn't go away, do bad stuff
242	(such as abort).	265	(such as abort).
243		266
244	Example: This is basically the same thing that libev does internally, too.	267	Example: This is basically the same thing that libev does internally, too.
…		…
255		278
256	=back	279	=back
257		280
258	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	281	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
259		282
260	An event loop is described by a C<struct ev_loop *>. The library knows two	283	An event loop is described by a C<struct ev_loop *> (the C<struct>
261	types of such loops, the I<default> loop, which supports signals and child	284	is I<not> optional in this case, as there is also an C<ev_loop>
262	events, and dynamically created loops which do not.	285	I<function>).
		286
		287	The library knows two types of such loops, the I<default> loop, which
		288	supports signals and child events, and dynamically created loops which do
		289	not.
263		290
264	=over 4	291	=over 4
265		292
266	=item struct ev_loop *ev_default_loop (unsigned int flags)	293	=item struct ev_loop *ev_default_loop (unsigned int flags)
267		294
…		…
273	If you don't know what event loop to use, use the one returned from this	300	If you don't know what event loop to use, use the one returned from this
274	function.	301	function.
275		302
276	Note that this function is I<not> thread-safe, so if you want to use it	303	Note that this function is I<not> thread-safe, so if you want to use it
277	from multiple threads, you have to lock (note also that this is unlikely,	304	from multiple threads, you have to lock (note also that this is unlikely,
278	as loops cannot bes hared easily between threads anyway).	305	as loops cannot be shared easily between threads anyway).
279		306
280	The default loop is the only loop that can handle C<ev_signal> and	307	The default loop is the only loop that can handle C<ev_signal> and
281	C<ev_child> watchers, and to do this, it always registers a handler	308	C<ev_child> watchers, and to do this, it always registers a handler
282	for C<SIGCHLD>. If this is a problem for your app you can either	309	for C<SIGCHLD>. If this is a problem for your application you can either
283	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	310	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
284	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	311	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
285	C<ev_default_init>.	312	C<ev_default_init>.
286		313
287	The flags argument can be used to specify special behaviour or specific	314	The flags argument can be used to specify special behaviour or specific
…		…
296	The default flags value. Use this if you have no clue (it's the right	323	The default flags value. Use this if you have no clue (it's the right
297	thing, believe me).	324	thing, believe me).
298		325
299	=item C<EVFLAG_NOENV>	326	=item C<EVFLAG_NOENV>
300		327
301	If this flag bit is ored into the flag value (or the program runs setuid	328	If this flag bit is or'ed into the flag value (or the program runs setuid
302	or setgid) then libev will I<not> look at the environment variable	329	or setgid) then libev will I<not> look at the environment variable
303	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	330	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
304	override the flags completely if it is found in the environment. This is	331	override the flags completely if it is found in the environment. This is
305	useful to try out specific backends to test their performance, or to work	332	useful to try out specific backends to test their performance, or to work
306	around bugs.	333	around bugs.
…		…
313		340
314	This works by calling C<getpid ()> on every iteration of the loop,	341	This works by calling C<getpid ()> on every iteration of the loop,
315	and thus this might slow down your event loop if you do a lot of loop	342	and thus this might slow down your event loop if you do a lot of loop
316	iterations and little real work, but is usually not noticeable (on my	343	iterations and little real work, but is usually not noticeable (on my
317	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	344	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
318	without a syscall and thus I<very> fast, but my GNU/Linux system also has	345	without a system call and thus I<very> fast, but my GNU/Linux system also has
319	C<pthread_atfork> which is even faster).	346	C<pthread_atfork> which is even faster).
320		347
321	The big advantage of this flag is that you can forget about fork (and	348	The big advantage of this flag is that you can forget about fork (and
322	forget about forgetting to tell libev about forking) when you use this	349	forget about forgetting to tell libev about forking) when you use this
323	flag.	350	flag.
324		351
325	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>	352	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
326	environment variable.	353	environment variable.
327		354
328	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	355	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
329		356
330	This is your standard select(2) backend. Not I<completely> standard, as	357	This is your standard select(2) backend. Not I<completely> standard, as
…		…
332	but if that fails, expect a fairly low limit on the number of fds when	359	but if that fails, expect a fairly low limit on the number of fds when
333	using this backend. It doesn't scale too well (O(highest_fd)), but its	360	using this backend. It doesn't scale too well (O(highest_fd)), but its
334	usually the fastest backend for a low number of (low-numbered :) fds.	361	usually the fastest backend for a low number of (low-numbered :) fds.
335		362
336	To get good performance out of this backend you need a high amount of	363	To get good performance out of this backend you need a high amount of
337	parallelity (most of the file descriptors should be busy). If you are	364	parallelism (most of the file descriptors should be busy). If you are
338	writing a server, you should C<accept ()> in a loop to accept as many	365	writing a server, you should C<accept ()> in a loop to accept as many
339	connections as possible during one iteration. You might also want to have	366	connections as possible during one iteration. You might also want to have
340	a look at C<ev_set_io_collect_interval ()> to increase the amount of	367	a look at C<ev_set_io_collect_interval ()> to increase the amount of
341	readiness notifications you get per iteration.	368	readiness notifications you get per iteration.
		369
		370	This backend maps C<EV_READ> to the C<readfds> set and C<EV_WRITE> to the
		371	C<writefds> set (and to work around Microsoft Windows bugs, also onto the
		372	C<exceptfds> set on that platform).
342		373
343	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	374	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
344		375
345	And this is your standard poll(2) backend. It's more complicated	376	And this is your standard poll(2) backend. It's more complicated
346	than select, but handles sparse fds better and has no artificial	377	than select, but handles sparse fds better and has no artificial
347	limit on the number of fds you can use (except it will slow down	378	limit on the number of fds you can use (except it will slow down
348	considerably with a lot of inactive fds). It scales similarly to select,	379	considerably with a lot of inactive fds). It scales similarly to select,
349	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for	380	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for
350	performance tips.	381	performance tips.
351		382
		383	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
		384	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
		385
352	=item C<EVBACKEND_EPOLL> (value 4, Linux)	386	=item C<EVBACKEND_EPOLL> (value 4, Linux)
353		387
354	For few fds, this backend is a bit little slower than poll and select,	388	For few fds, this backend is a bit little slower than poll and select,
355	but it scales phenomenally better. While poll and select usually scale	389	but it scales phenomenally better. While poll and select usually scale
356	like O(total_fds) where n is the total number of fds (or the highest fd),	390	like O(total_fds) where n is the total number of fds (or the highest fd),
357	epoll scales either O(1) or O(active_fds). The epoll design has a number	391	epoll scales either O(1) or O(active_fds).
358	of shortcomings, such as silently dropping events in some hard-to-detect	392
359	cases and requiring a syscall per fd change, no fork support and bad	393	The epoll mechanism deserves honorable mention as the most misdesigned
360	support for dup.	394	of the more advanced event mechanisms: mere annoyances include silently
		395	dropping file descriptors, requiring a system call per change per file
		396	descriptor (and unnecessary guessing of parameters), problems with dup and
		397	so on. The biggest issue is fork races, however - if a program forks then
		398	I<both> parent and child process have to recreate the epoll set, which can
		399	take considerable time (one syscall per file descriptor) and is of course
		400	hard to detect.
		401
		402	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
		403	of course I<doesn't>, and epoll just loves to report events for totally
		404	I<different> file descriptors (even already closed ones, so one cannot
		405	even remove them from the set) than registered in the set (especially
		406	on SMP systems). Libev tries to counter these spurious notifications by
		407	employing an additional generation counter and comparing that against the
		408	events to filter out spurious ones, recreating the set when required.
361		409
362	While stopping, setting and starting an I/O watcher in the same iteration	410	While stopping, setting and starting an I/O watcher in the same iteration
363	will result in some caching, there is still a syscall per such incident	411	will result in some caching, there is still a system call per such
364	(because the fd could point to a different file description now), so its	412	incident (because the same I<file descriptor> could point to a different
365	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	413	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
366	very well if you register events for both fds.	414	file descriptors might not work very well if you register events for both
367		415	file descriptors.
368	Please note that epoll sometimes generates spurious notifications, so you
369	need to use non-blocking I/O or other means to avoid blocking when no data
370	(or space) is available.
371		416
372	Best performance from this backend is achieved by not unregistering all	417	Best performance from this backend is achieved by not unregistering all
373	watchers for a file descriptor until it has been closed, if possible, i.e.	418	watchers for a file descriptor until it has been closed, if possible,
374	keep at least one watcher active per fd at all times.	419	i.e. keep at least one watcher active per fd at all times. Stopping and
		420	starting a watcher (without re-setting it) also usually doesn't cause
		421	extra overhead. A fork can both result in spurious notifications as well
		422	as in libev having to destroy and recreate the epoll object, which can
		423	take considerable time and thus should be avoided.
375		424
		425	All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or
		426	faster than epoll for maybe up to a hundred file descriptors, depending on
		427	the usage. So sad.
		428
376	While nominally embeddeble in other event loops, this feature is broken in	429	While nominally embeddable in other event loops, this feature is broken in
377	all kernel versions tested so far.	430	all kernel versions tested so far.
		431
		432	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
		433	C<EVBACKEND_POLL>.
378		434
379	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	435	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
380		436
381	Kqueue deserves special mention, as at the time of this writing, it	437	Kqueue deserves special mention, as at the time of this writing, it
382	was broken on all BSDs except NetBSD (usually it doesn't work reliably	438	was broken on all BSDs except NetBSD (usually it doesn't work reliably
383	with anything but sockets and pipes, except on Darwin, where of course	439	with anything but sockets and pipes, except on Darwin, where of course
384	it's completely useless). For this reason it's not being "autodetected"	440	it's completely useless). Unlike epoll, however, whose brokenness
		441	is by design, these kqueue bugs can (and eventually will) be fixed
		442	without API changes to existing programs. For this reason it's not being
385	unless you explicitly specify it explicitly in the flags (i.e. using	443	"auto-detected" unless you explicitly specify it in the flags (i.e. using
386	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)	444	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
387	system like NetBSD.	445	system like NetBSD.
388		446
389	You still can embed kqueue into a normal poll or select backend and use it	447	You still can embed kqueue into a normal poll or select backend and use it
390	only for sockets (after having made sure that sockets work with kqueue on	448	only for sockets (after having made sure that sockets work with kqueue on
391	the target platform). See C<ev_embed> watchers for more info.	449	the target platform). See C<ev_embed> watchers for more info.
392		450
393	It scales in the same way as the epoll backend, but the interface to the	451	It scales in the same way as the epoll backend, but the interface to the
394	kernel is more efficient (which says nothing about its actual speed, of	452	kernel is more efficient (which says nothing about its actual speed, of
395	course). While stopping, setting and starting an I/O watcher does never	453	course). While stopping, setting and starting an I/O watcher does never
396	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to	454	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
397	two event changes per incident, support for C<fork ()> is very bad and it	455	two event changes per incident. Support for C<fork ()> is very bad (but
398	drops fds silently in similarly hard-to-detect cases.	456	sane, unlike epoll) and it drops fds silently in similarly hard-to-detect
		457	cases
399		458
400	This backend usually performs well under most conditions.	459	This backend usually performs well under most conditions.
401		460
402	While nominally embeddable in other event loops, this doesn't work	461	While nominally embeddable in other event loops, this doesn't work
403	everywhere, so you might need to test for this. And since it is broken	462	everywhere, so you might need to test for this. And since it is broken
404	almost everywhere, you should only use it when you have a lot of sockets	463	almost everywhere, you should only use it when you have a lot of sockets
405	(for which it usually works), by embedding it into another event loop	464	(for which it usually works), by embedding it into another event loop
406	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for	465	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> (but C<poll> is of course
407	sockets.	466	also broken on OS X)) and, did I mention it, using it only for sockets.
		467
		468	This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with
		469	C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with
		470	C<NOTE_EOF>.
408		471
409	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	472	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
410		473
411	This is not implemented yet (and might never be, unless you send me an	474	This is not implemented yet (and might never be, unless you send me an
412	implementation). According to reports, C</dev/poll> only supports sockets	475	implementation). According to reports, C</dev/poll> only supports sockets
…		…
416	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	479	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
417		480
418	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	481	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
419	it's really slow, but it still scales very well (O(active_fds)).	482	it's really slow, but it still scales very well (O(active_fds)).
420		483
421	Please note that solaris event ports can deliver a lot of spurious	484	Please note that Solaris event ports can deliver a lot of spurious
422	notifications, so you need to use non-blocking I/O or other means to avoid	485	notifications, so you need to use non-blocking I/O or other means to avoid
423	blocking when no data (or space) is available.	486	blocking when no data (or space) is available.
424		487
425	While this backend scales well, it requires one system call per active	488	While this backend scales well, it requires one system call per active
426	file descriptor per loop iteration. For small and medium numbers of file	489	file descriptor per loop iteration. For small and medium numbers of file
427	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	490	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
428	might perform better.	491	might perform better.
429		492
430	On the positive side, ignoring the spurious readiness notifications, this	493	On the positive side, with the exception of the spurious readiness
431	backend actually performed to specification in all tests and is fully	494	notifications, this backend actually performed fully to specification
432	embeddable, which is a rare feat among the OS-specific backends.	495	in all tests and is fully embeddable, which is a rare feat among the
		496	OS-specific backends (I vastly prefer correctness over speed hacks).
		497
		498	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
		499	C<EVBACKEND_POLL>.
433		500
434	=item C<EVBACKEND_ALL>	501	=item C<EVBACKEND_ALL>
435		502
436	Try all backends (even potentially broken ones that wouldn't be tried	503	Try all backends (even potentially broken ones that wouldn't be tried
437	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	504	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
…		…
439		506
440	It is definitely not recommended to use this flag.	507	It is definitely not recommended to use this flag.
441		508
442	=back	509	=back
443		510
444	If one or more of these are ored into the flags value, then only these	511	If one or more of these are or'ed into the flags value, then only these
445	backends will be tried (in the reverse order as listed here). If none are	512	backends will be tried (in the reverse order as listed here). If none are
446	specified, all backends in C<ev_recommended_backends ()> will be tried.	513	specified, all backends in C<ev_recommended_backends ()> will be tried.
447		514
448	The most typical usage is like this:	515	Example: This is the most typical usage.
449		516
450	if (!ev_default_loop (0))	517	if (!ev_default_loop (0))
451	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	518	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
452		519
453	Restrict libev to the select and poll backends, and do not allow	520	Example: Restrict libev to the select and poll backends, and do not allow
454	environment settings to be taken into account:	521	environment settings to be taken into account:
455		522
456	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	523	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
457		524
458	Use whatever libev has to offer, but make sure that kqueue is used if	525	Example: Use whatever libev has to offer, but make sure that kqueue is
459	available (warning, breaks stuff, best use only with your own private	526	used if available (warning, breaks stuff, best use only with your own
460	event loop and only if you know the OS supports your types of fds):	527	private event loop and only if you know the OS supports your types of
		528	fds):
461		529
462	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	530	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
463		531
464	=item struct ev_loop *ev_loop_new (unsigned int flags)	532	=item struct ev_loop *ev_loop_new (unsigned int flags)
465		533
466	Similar to C<ev_default_loop>, but always creates a new event loop that is	534	Similar to C<ev_default_loop>, but always creates a new event loop that is
467	always distinct from the default loop. Unlike the default loop, it cannot	535	always distinct from the default loop. Unlike the default loop, it cannot
…		…
472	libev with threads is indeed to create one loop per thread, and using the	540	libev with threads is indeed to create one loop per thread, and using the
473	default loop in the "main" or "initial" thread.	541	default loop in the "main" or "initial" thread.
474		542
475	Example: Try to create a event loop that uses epoll and nothing else.	543	Example: Try to create a event loop that uses epoll and nothing else.
476		544
477	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	545	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
478	if (!epoller)	546	if (!epoller)
479	fatal ("no epoll found here, maybe it hides under your chair");	547	fatal ("no epoll found here, maybe it hides under your chair");
480		548
481	=item ev_default_destroy ()	549	=item ev_default_destroy ()
482		550
483	Destroys the default loop again (frees all memory and kernel state	551	Destroys the default loop again (frees all memory and kernel state
484	etc.). None of the active event watchers will be stopped in the normal	552	etc.). None of the active event watchers will be stopped in the normal
485	sense, so e.g. C<ev_is_active> might still return true. It is your	553	sense, so e.g. C<ev_is_active> might still return true. It is your
486	responsibility to either stop all watchers cleanly yoursef I<before>	554	responsibility to either stop all watchers cleanly yourself I<before>
487	calling this function, or cope with the fact afterwards (which is usually	555	calling this function, or cope with the fact afterwards (which is usually
488	the easiest thing, you can just ignore the watchers and/or C<free ()> them	556	the easiest thing, you can just ignore the watchers and/or C<free ()> them
489	for example).	557	for example).
490		558
491	Note that certain global state, such as signal state, will not be freed by	559	Note that certain global state, such as signal state (and installed signal
492	this function, and related watchers (such as signal and child watchers)	560	handlers), will not be freed by this function, and related watchers (such
493	would need to be stopped manually.	561	as signal and child watchers) would need to be stopped manually.
494		562
495	In general it is not advisable to call this function except in the	563	In general it is not advisable to call this function except in the
496	rare occasion where you really need to free e.g. the signal handling	564	rare occasion where you really need to free e.g. the signal handling
497	pipe fds. If you need dynamically allocated loops it is better to use	565	pipe fds. If you need dynamically allocated loops it is better to use
498	C<ev_loop_new> and C<ev_loop_destroy>).	566	C<ev_loop_new> and C<ev_loop_destroy>).
…		…
523		591
524	=item ev_loop_fork (loop)	592	=item ev_loop_fork (loop)
525		593
526	Like C<ev_default_fork>, but acts on an event loop created by	594	Like C<ev_default_fork>, but acts on an event loop created by
527	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	595	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
528	after fork, and how you do this is entirely your own problem.	596	after fork that you want to re-use in the child, and how you do this is
		597	entirely your own problem.
529		598
530	=item int ev_is_default_loop (loop)	599	=item int ev_is_default_loop (loop)
531		600
532	Returns true when the given loop actually is the default loop, false otherwise.	601	Returns true when the given loop is, in fact, the default loop, and false
		602	otherwise.
533		603
534	=item unsigned int ev_loop_count (loop)	604	=item unsigned int ev_loop_count (loop)
535		605
536	Returns the count of loop iterations for the loop, which is identical to	606	Returns the count of loop iterations for the loop, which is identical to
537	the number of times libev did poll for new events. It starts at C<0> and	607	the number of times libev did poll for new events. It starts at C<0> and
…		…
552	received events and started processing them. This timestamp does not	622	received events and started processing them. This timestamp does not
553	change as long as callbacks are being processed, and this is also the base	623	change as long as callbacks are being processed, and this is also the base
554	time used for relative timers. You can treat it as the timestamp of the	624	time used for relative timers. You can treat it as the timestamp of the
555	event occurring (or more correctly, libev finding out about it).	625	event occurring (or more correctly, libev finding out about it).
556		626
		627	=item ev_now_update (loop)
		628
		629	Establishes the current time by querying the kernel, updating the time
		630	returned by C<ev_now ()> in the progress. This is a costly operation and
		631	is usually done automatically within C<ev_loop ()>.
		632
		633	This function is rarely useful, but when some event callback runs for a
		634	very long time without entering the event loop, updating libev's idea of
		635	the current time is a good idea.
		636
		637	See also "The special problem of time updates" in the C<ev_timer> section.
		638
557	=item ev_loop (loop, int flags)	639	=item ev_loop (loop, int flags)
558		640
559	Finally, this is it, the event handler. This function usually is called	641	Finally, this is it, the event handler. This function usually is called
560	after you initialised all your watchers and you want to start handling	642	after you initialised all your watchers and you want to start handling
561	events.	643	events.
…		…
563	If the flags argument is specified as C<0>, it will not return until	645	If the flags argument is specified as C<0>, it will not return until
564	either no event watchers are active anymore or C<ev_unloop> was called.	646	either no event watchers are active anymore or C<ev_unloop> was called.
565		647
566	Please note that an explicit C<ev_unloop> is usually better than	648	Please note that an explicit C<ev_unloop> is usually better than
567	relying on all watchers to be stopped when deciding when a program has	649	relying on all watchers to be stopped when deciding when a program has
568	finished (especially in interactive programs), but having a program that	650	finished (especially in interactive programs), but having a program
569	automatically loops as long as it has to and no longer by virtue of	651	that automatically loops as long as it has to and no longer by virtue
570	relying on its watchers stopping correctly is a thing of beauty.	652	of relying on its watchers stopping correctly, that is truly a thing of
		653	beauty.
571		654
572	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	655	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
573	those events and any outstanding ones, but will not block your process in	656	those events and any already outstanding ones, but will not block your
574	case there are no events and will return after one iteration of the loop.	657	process in case there are no events and will return after one iteration of
		658	the loop.
575		659
576	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	660	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
577	neccessary) and will handle those and any outstanding ones. It will block	661	necessary) and will handle those and any already outstanding ones. It
578	your process until at least one new event arrives, and will return after	662	will block your process until at least one new event arrives (which could
579	one iteration of the loop. This is useful if you are waiting for some	663	be an event internal to libev itself, so there is no guarantee that a
580	external event in conjunction with something not expressible using other	664	user-registered callback will be called), and will return after one
		665	iteration of the loop.
		666
		667	This is useful if you are waiting for some external event in conjunction
		668	with something not expressible using other libev watchers (i.e. "roll your
581	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	669	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
582	usually a better approach for this kind of thing.	670	usually a better approach for this kind of thing.
583		671
584	Here are the gory details of what C<ev_loop> does:	672	Here are the gory details of what C<ev_loop> does:
585		673
586	- Before the first iteration, call any pending watchers.	674	- Before the first iteration, call any pending watchers.
587	* If EVFLAG_FORKCHECK was used, check for a fork.	675	* If EVFLAG_FORKCHECK was used, check for a fork.
588	- If a fork was detected, queue and call all fork watchers.	676	- If a fork was detected (by any means), queue and call all fork watchers.
589	- Queue and call all prepare watchers.	677	- Queue and call all prepare watchers.
590	- If we have been forked, recreate the kernel state.	678	- If we have been forked, detach and recreate the kernel state
		679	as to not disturb the other process.
591	- Update the kernel state with all outstanding changes.	680	- Update the kernel state with all outstanding changes.
592	- Update the "event loop time".	681	- Update the "event loop time" (ev_now ()).
593	- Calculate for how long to sleep or block, if at all	682	- Calculate for how long to sleep or block, if at all
594	(active idle watchers, EVLOOP_NONBLOCK or not having	683	(active idle watchers, EVLOOP_NONBLOCK or not having
595	any active watchers at all will result in not sleeping).	684	any active watchers at all will result in not sleeping).
596	- Sleep if the I/O and timer collect interval say so.	685	- Sleep if the I/O and timer collect interval say so.
597	- Block the process, waiting for any events.	686	- Block the process, waiting for any events.
598	- Queue all outstanding I/O (fd) events.	687	- Queue all outstanding I/O (fd) events.
599	- Update the "event loop time" and do time jump handling.	688	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
600	- Queue all outstanding timers.	689	- Queue all expired timers.
601	- Queue all outstanding periodics.	690	- Queue all expired periodics.
602	- If no events are pending now, queue all idle watchers.	691	- Unless any events are pending now, queue all idle watchers.
603	- Queue all check watchers.	692	- Queue all check watchers.
604	- Call all queued watchers in reverse order (i.e. check watchers first).	693	- Call all queued watchers in reverse order (i.e. check watchers first).
605	Signals and child watchers are implemented as I/O watchers, and will	694	Signals and child watchers are implemented as I/O watchers, and will
606	be handled here by queueing them when their watcher gets executed.	695	be handled here by queueing them when their watcher gets executed.
607	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	696	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
…		…
612	anymore.	701	anymore.
613		702
614	... queue jobs here, make sure they register event watchers as long	703	... queue jobs here, make sure they register event watchers as long
615	... as they still have work to do (even an idle watcher will do..)	704	... as they still have work to do (even an idle watcher will do..)
616	ev_loop (my_loop, 0);	705	ev_loop (my_loop, 0);
617	... jobs done. yeah!	706	... jobs done or somebody called unloop. yeah!
618		707
619	=item ev_unloop (loop, how)	708	=item ev_unloop (loop, how)
620		709
621	Can be used to make a call to C<ev_loop> return early (but only after it	710	Can be used to make a call to C<ev_loop> return early (but only after it
622	has processed all outstanding events). The C<how> argument must be either	711	has processed all outstanding events). The C<how> argument must be either
623	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	712	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or
624	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	713	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
625		714
626	This "unloop state" will be cleared when entering C<ev_loop> again.	715	This "unloop state" will be cleared when entering C<ev_loop> again.
627		716
		717	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.
		718
628	=item ev_ref (loop)	719	=item ev_ref (loop)
629		720
630	=item ev_unref (loop)	721	=item ev_unref (loop)
631		722
632	Ref/unref can be used to add or remove a reference count on the event	723	Ref/unref can be used to add or remove a reference count on the event
633	loop: Every watcher keeps one reference, and as long as the reference	724	loop: Every watcher keeps one reference, and as long as the reference
634	count is nonzero, C<ev_loop> will not return on its own. If you have	725	count is nonzero, C<ev_loop> will not return on its own.
		726
635	a watcher you never unregister that should not keep C<ev_loop> from	727	If you have a watcher you never unregister that should not keep C<ev_loop>
636	returning, ev_unref() after starting, and ev_ref() before stopping it. For	728	from returning, call ev_unref() after starting, and ev_ref() before
		729	stopping it.
		730
637	example, libev itself uses this for its internal signal pipe: It is not	731	As an example, libev itself uses this for its internal signal pipe: It
638	visible to the libev user and should not keep C<ev_loop> from exiting if	732	is not visible to the libev user and should not keep C<ev_loop> from
639	no event watchers registered by it are active. It is also an excellent	733	exiting if no event watchers registered by it are active. It is also an
640	way to do this for generic recurring timers or from within third-party	734	excellent way to do this for generic recurring timers or from within
641	libraries. Just remember to I<unref after start> and I<ref before stop>	735	third-party libraries. Just remember to I<unref after start> and I<ref
642	(but only if the watcher wasn't active before, or was active before,	736	before stop> (but only if the watcher wasn't active before, or was active
643	respectively).	737	before, respectively. Note also that libev might stop watchers itself
		738	(e.g. non-repeating timers) in which case you have to C<ev_ref>
		739	in the callback).
644		740
645	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	741	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
646	running when nothing else is active.	742	running when nothing else is active.
647		743
648	struct ev_signal exitsig;	744	ev_signal exitsig;
649	ev_signal_init (&exitsig, sig_cb, SIGINT);	745	ev_signal_init (&exitsig, sig_cb, SIGINT);
650	ev_signal_start (loop, &exitsig);	746	ev_signal_start (loop, &exitsig);
651	evf_unref (loop);	747	evf_unref (loop);
652		748
653	Example: For some weird reason, unregister the above signal handler again.	749	Example: For some weird reason, unregister the above signal handler again.
654		750
655	ev_ref (loop);	751	ev_ref (loop);
656	ev_signal_stop (loop, &exitsig);	752	ev_signal_stop (loop, &exitsig);
657		753
658	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	754	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
659		755
660	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	756	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
661		757
662	These advanced functions influence the time that libev will spend waiting	758	These advanced functions influence the time that libev will spend waiting
663	for events. Both are by default C<0>, meaning that libev will try to	759	for events. Both time intervals are by default C<0>, meaning that libev
664	invoke timer/periodic callbacks and I/O callbacks with minimum latency.	760	will try to invoke timer/periodic callbacks and I/O callbacks with minimum
		761	latency.
665		762
666	Setting these to a higher value (the C<interval> I<must> be >= C<0>)	763	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
667	allows libev to delay invocation of I/O and timer/periodic callbacks to	764	allows libev to delay invocation of I/O and timer/periodic callbacks
668	increase efficiency of loop iterations.	765	to increase efficiency of loop iterations (or to increase power-saving
		766	opportunities).
669		767
670	The background is that sometimes your program runs just fast enough to	768	The idea is that sometimes your program runs just fast enough to handle
671	handle one (or very few) event(s) per loop iteration. While this makes	769	one (or very few) event(s) per loop iteration. While this makes the
672	the program responsive, it also wastes a lot of CPU time to poll for new	770	program responsive, it also wastes a lot of CPU time to poll for new
673	events, especially with backends like C<select ()> which have a high	771	events, especially with backends like C<select ()> which have a high
674	overhead for the actual polling but can deliver many events at once.	772	overhead for the actual polling but can deliver many events at once.
675		773
676	By setting a higher I<io collect interval> you allow libev to spend more	774	By setting a higher I<io collect interval> you allow libev to spend more
677	time collecting I/O events, so you can handle more events per iteration,	775	time collecting I/O events, so you can handle more events per iteration,
…		…
679	C<ev_timer>) will be not affected. Setting this to a non-null value will	777	C<ev_timer>) will be not affected. Setting this to a non-null value will
680	introduce an additional C<ev_sleep ()> call into most loop iterations.	778	introduce an additional C<ev_sleep ()> call into most loop iterations.
681		779
682	Likewise, by setting a higher I<timeout collect interval> you allow libev	780	Likewise, by setting a higher I<timeout collect interval> you allow libev
683	to spend more time collecting timeouts, at the expense of increased	781	to spend more time collecting timeouts, at the expense of increased
684	latency (the watcher callback will be called later). C<ev_io> watchers	782	latency/jitter/inexactness (the watcher callback will be called
685	will not be affected. Setting this to a non-null value will not introduce	783	later). C<ev_io> watchers will not be affected. Setting this to a non-null
686	any overhead in libev.	784	value will not introduce any overhead in libev.
687		785
688	Many (busy) programs can usually benefit by setting the io collect	786	Many (busy) programs can usually benefit by setting the I/O collect
689	interval to a value near C<0.1> or so, which is often enough for	787	interval to a value near C<0.1> or so, which is often enough for
690	interactive servers (of course not for games), likewise for timeouts. It	788	interactive servers (of course not for games), likewise for timeouts. It
691	usually doesn't make much sense to set it to a lower value than C<0.01>,	789	usually doesn't make much sense to set it to a lower value than C<0.01>,
692	as this approsaches the timing granularity of most systems.	790	as this approaches the timing granularity of most systems.
		791
		792	Setting the I<timeout collect interval> can improve the opportunity for
		793	saving power, as the program will "bundle" timer callback invocations that
		794	are "near" in time together, by delaying some, thus reducing the number of
		795	times the process sleeps and wakes up again. Another useful technique to
		796	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
		797	they fire on, say, one-second boundaries only.
693		798
694	=item ev_loop_verify (loop)	799	=item ev_loop_verify (loop)
695		800
696	This function only does something when C<EV_VERIFY> support has been	801	This function only does something when C<EV_VERIFY> support has been
697	compiled in. It tries to go through all internal structures and checks	802	compiled in, which is the default for non-minimal builds. It tries to go
698	them for validity. If anything is found to be inconsistent, it will print	803	through all internal structures and checks them for validity. If anything
699	an error message to standard error and call C<abort ()>.	804	is found to be inconsistent, it will print an error message to standard
		805	error and call C<abort ()>.
700		806
701	This can be used to catch bugs inside libev itself: under normal	807	This can be used to catch bugs inside libev itself: under normal
702	circumstances, this function will never abort as of course libev keeps its	808	circumstances, this function will never abort as of course libev keeps its
703	data structures consistent.	809	data structures consistent.
704		810
705	=back	811	=back
706		812
707		813
708	=head1 ANATOMY OF A WATCHER	814	=head1 ANATOMY OF A WATCHER
709		815
		816	In the following description, uppercase C<TYPE> in names stands for the
		817	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
		818	watchers and C<ev_io_start> for I/O watchers.
		819
710	A watcher is a structure that you create and register to record your	820	A watcher is a structure that you create and register to record your
711	interest in some event. For instance, if you want to wait for STDIN to	821	interest in some event. For instance, if you want to wait for STDIN to
712	become readable, you would create an C<ev_io> watcher for that:	822	become readable, you would create an C<ev_io> watcher for that:
713		823
714	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	824	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
715	{	825	{
716	ev_io_stop (w);	826	ev_io_stop (w);
717	ev_unloop (loop, EVUNLOOP_ALL);	827	ev_unloop (loop, EVUNLOOP_ALL);
718	}	828	}
719		829
720	struct ev_loop *loop = ev_default_loop (0);	830	struct ev_loop *loop = ev_default_loop (0);
		831
721	struct ev_io stdin_watcher;	832	ev_io stdin_watcher;
		833
722	ev_init (&stdin_watcher, my_cb);	834	ev_init (&stdin_watcher, my_cb);
723	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	835	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
724	ev_io_start (loop, &stdin_watcher);	836	ev_io_start (loop, &stdin_watcher);
		837
725	ev_loop (loop, 0);	838	ev_loop (loop, 0);
726		839
727	As you can see, you are responsible for allocating the memory for your	840	As you can see, you are responsible for allocating the memory for your
728	watcher structures (and it is usually a bad idea to do this on the stack,	841	watcher structures (and it is I<usually> a bad idea to do this on the
729	although this can sometimes be quite valid).	842	stack).
		843
		844	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
		845	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
730		846
731	Each watcher structure must be initialised by a call to C<ev_init	847	Each watcher structure must be initialised by a call to C<ev_init
732	(watcher *, callback)>, which expects a callback to be provided. This	848	(watcher *, callback)>, which expects a callback to be provided. This
733	callback gets invoked each time the event occurs (or, in the case of io	849	callback gets invoked each time the event occurs (or, in the case of I/O
734	watchers, each time the event loop detects that the file descriptor given	850	watchers, each time the event loop detects that the file descriptor given
735	is readable and/or writable).	851	is readable and/or writable).
736		852
737	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	853	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
738	with arguments specific to this watcher type. There is also a macro	854	macro to configure it, with arguments specific to the watcher type. There
739	to combine initialisation and setting in one call: C<< ev_<type>_init	855	is also a macro to combine initialisation and setting in one call: C<<
740	(watcher *, callback, ...) >>.	856	ev_TYPE_init (watcher *, callback, ...) >>.
741		857
742	To make the watcher actually watch out for events, you have to start it	858	To make the watcher actually watch out for events, you have to start it
743	with a watcher-specific start function (C<< ev_<type>_start (loop, watcher	859	with a watcher-specific start function (C<< ev_TYPE_start (loop, watcher
744	*) >>), and you can stop watching for events at any time by calling the	860	*) >>), and you can stop watching for events at any time by calling the
745	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.	861	corresponding stop function (C<< ev_TYPE_stop (loop, watcher *) >>.
746		862
747	As long as your watcher is active (has been started but not stopped) you	863	As long as your watcher is active (has been started but not stopped) you
748	must not touch the values stored in it. Most specifically you must never	864	must not touch the values stored in it. Most specifically you must never
749	reinitialise it or call its C<set> macro.	865	reinitialise it or call its C<ev_TYPE_set> macro.
750		866
751	Each and every callback receives the event loop pointer as first, the	867	Each and every callback receives the event loop pointer as first, the
752	registered watcher structure as second, and a bitset of received events as	868	registered watcher structure as second, and a bitset of received events as
753	third argument.	869	third argument.
754		870
…		…
812		928
813	=item C<EV_ASYNC>	929	=item C<EV_ASYNC>
814		930
815	The given async watcher has been asynchronously notified (see C<ev_async>).	931	The given async watcher has been asynchronously notified (see C<ev_async>).
816		932
		933	=item C<EV_CUSTOM>
		934
		935	Not ever sent (or otherwise used) by libev itself, but can be freely used
		936	by libev users to signal watchers (e.g. via C<ev_feed_event>).
		937
817	=item C<EV_ERROR>	938	=item C<EV_ERROR>
818		939
819	An unspecified error has occured, the watcher has been stopped. This might	940	An unspecified error has occurred, the watcher has been stopped. This might
820	happen because the watcher could not be properly started because libev	941	happen because the watcher could not be properly started because libev
821	ran out of memory, a file descriptor was found to be closed or any other	942	ran out of memory, a file descriptor was found to be closed or any other
		943	problem. Libev considers these application bugs.
		944
822	problem. You best act on it by reporting the problem and somehow coping	945	You best act on it by reporting the problem and somehow coping with the
823	with the watcher being stopped.	946	watcher being stopped. Note that well-written programs should not receive
		947	an error ever, so when your watcher receives it, this usually indicates a
		948	bug in your program.
824		949
825	Libev will usually signal a few "dummy" events together with an error,	950	Libev will usually signal a few "dummy" events together with an error, for
826	for example it might indicate that a fd is readable or writable, and if	951	example it might indicate that a fd is readable or writable, and if your
827	your callbacks is well-written it can just attempt the operation and cope	952	callbacks is well-written it can just attempt the operation and cope with
828	with the error from read() or write(). This will not work in multithreaded	953	the error from read() or write(). This will not work in multi-threaded
829	programs, though, so beware.	954	programs, though, as the fd could already be closed and reused for another
		955	thing, so beware.
830		956
831	=back	957	=back
832		958
833	=head2 GENERIC WATCHER FUNCTIONS	959	=head2 GENERIC WATCHER FUNCTIONS
834
835	In the following description, C<TYPE> stands for the watcher type,
836	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.
837		960
838	=over 4	961	=over 4
839		962
840	=item C<ev_init> (ev_TYPE *watcher, callback)	963	=item C<ev_init> (ev_TYPE *watcher, callback)
841		964
…		…
847	which rolls both calls into one.	970	which rolls both calls into one.
848		971
849	You can reinitialise a watcher at any time as long as it has been stopped	972	You can reinitialise a watcher at any time as long as it has been stopped
850	(or never started) and there are no pending events outstanding.	973	(or never started) and there are no pending events outstanding.
851		974
852	The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher,	975	The callback is always of type C<void (*)(struct ev_loop *loop, ev_TYPE *watcher,
853	int revents)>.	976	int revents)>.
		977
		978	Example: Initialise an C<ev_io> watcher in two steps.
		979
		980	ev_io w;
		981	ev_init (&w, my_cb);
		982	ev_io_set (&w, STDIN_FILENO, EV_READ);
854		983
855	=item C<ev_TYPE_set> (ev_TYPE *, [args])	984	=item C<ev_TYPE_set> (ev_TYPE *, [args])
856		985
857	This macro initialises the type-specific parts of a watcher. You need to	986	This macro initialises the type-specific parts of a watcher. You need to
858	call C<ev_init> at least once before you call this macro, but you can	987	call C<ev_init> at least once before you call this macro, but you can
…		…
861	difference to the C<ev_init> macro).	990	difference to the C<ev_init> macro).
862		991
863	Although some watcher types do not have type-specific arguments	992	Although some watcher types do not have type-specific arguments
864	(e.g. C<ev_prepare>) you still need to call its C<set> macro.	993	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
865		994
		995	See C<ev_init>, above, for an example.
		996
866	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	997	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
867		998
868	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	999	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
869	calls into a single call. This is the most convinient method to initialise	1000	calls into a single call. This is the most convenient method to initialise
870	a watcher. The same limitations apply, of course.	1001	a watcher. The same limitations apply, of course.
		1002
		1003	Example: Initialise and set an C<ev_io> watcher in one step.
		1004
		1005	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
871		1006
872	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	1007	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
873		1008
874	Starts (activates) the given watcher. Only active watchers will receive	1009	Starts (activates) the given watcher. Only active watchers will receive
875	events. If the watcher is already active nothing will happen.	1010	events. If the watcher is already active nothing will happen.
876		1011
		1012	Example: Start the C<ev_io> watcher that is being abused as example in this
		1013	whole section.
		1014
		1015	ev_io_start (EV_DEFAULT_UC, &w);
		1016
877	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)	1017	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)
878		1018
879	Stops the given watcher again (if active) and clears the pending	1019	Stops the given watcher if active, and clears the pending status (whether
		1020	the watcher was active or not).
		1021
880	status. It is possible that stopped watchers are pending (for example,	1022	It is possible that stopped watchers are pending - for example,
881	non-repeating timers are being stopped when they become pending), but	1023	non-repeating timers are being stopped when they become pending - but
882	C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If	1024	calling C<ev_TYPE_stop> ensures that the watcher is neither active nor
883	you want to free or reuse the memory used by the watcher it is therefore a	1025	pending. If you want to free or reuse the memory used by the watcher it is
884	good idea to always call its C<ev_TYPE_stop> function.	1026	therefore a good idea to always call its C<ev_TYPE_stop> function.
885		1027
886	=item bool ev_is_active (ev_TYPE *watcher)	1028	=item bool ev_is_active (ev_TYPE *watcher)
887		1029
888	Returns a true value iff the watcher is active (i.e. it has been started	1030	Returns a true value iff the watcher is active (i.e. it has been started
889	and not yet been stopped). As long as a watcher is active you must not modify	1031	and not yet been stopped). As long as a watcher is active you must not modify
…		…
931	The default priority used by watchers when no priority has been set is	1073	The default priority used by watchers when no priority has been set is
932	always C<0>, which is supposed to not be too high and not be too low :).	1074	always C<0>, which is supposed to not be too high and not be too low :).
933		1075
934	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is	1076	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
935	fine, as long as you do not mind that the priority value you query might	1077	fine, as long as you do not mind that the priority value you query might
936	or might not have been adjusted to be within valid range.	1078	or might not have been clamped to the valid range.
937		1079
938	=item ev_invoke (loop, ev_TYPE *watcher, int revents)	1080	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
939		1081
940	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither	1082	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
941	C<loop> nor C<revents> need to be valid as long as the watcher callback	1083	C<loop> nor C<revents> need to be valid as long as the watcher callback
942	can deal with that fact.	1084	can deal with that fact, as both are simply passed through to the
		1085	callback.
943		1086
944	=item int ev_clear_pending (loop, ev_TYPE *watcher)	1087	=item int ev_clear_pending (loop, ev_TYPE *watcher)
945		1088
946	If the watcher is pending, this function returns clears its pending status	1089	If the watcher is pending, this function clears its pending status and
947	and returns its C<revents> bitset (as if its callback was invoked). If the	1090	returns its C<revents> bitset (as if its callback was invoked). If the
948	watcher isn't pending it does nothing and returns C<0>.	1091	watcher isn't pending it does nothing and returns C<0>.
949		1092
		1093	Sometimes it can be useful to "poll" a watcher instead of waiting for its
		1094	callback to be invoked, which can be accomplished with this function.
		1095
950	=back	1096	=back
951		1097
952		1098
953	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1099	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
954		1100
955	Each watcher has, by default, a member C<void *data> that you can change	1101	Each watcher has, by default, a member C<void *data> that you can change
956	and read at any time, libev will completely ignore it. This can be used	1102	and read at any time: libev will completely ignore it. This can be used
957	to associate arbitrary data with your watcher. If you need more data and	1103	to associate arbitrary data with your watcher. If you need more data and
958	don't want to allocate memory and store a pointer to it in that data	1104	don't want to allocate memory and store a pointer to it in that data
959	member, you can also "subclass" the watcher type and provide your own	1105	member, you can also "subclass" the watcher type and provide your own
960	data:	1106	data:
961		1107
962	struct my_io	1108	struct my_io
963	{	1109	{
964	struct ev_io io;	1110	ev_io io;
965	int otherfd;	1111	int otherfd;
966	void *somedata;	1112	void *somedata;
967	struct whatever *mostinteresting;	1113	struct whatever *mostinteresting;
968	}	1114	};
		1115
		1116	...
		1117	struct my_io w;
		1118	ev_io_init (&w.io, my_cb, fd, EV_READ);
969		1119
970	And since your callback will be called with a pointer to the watcher, you	1120	And since your callback will be called with a pointer to the watcher, you
971	can cast it back to your own type:	1121	can cast it back to your own type:
972		1122
973	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	1123	static void my_cb (struct ev_loop *loop, ev_io *w_, int revents)
974	{	1124	{
975	struct my_io *w = (struct my_io *)w_;	1125	struct my_io *w = (struct my_io *)w_;
976	...	1126	...
977	}	1127	}
978		1128
979	More interesting and less C-conformant ways of casting your callback type	1129	More interesting and less C-conformant ways of casting your callback type
980	instead have been omitted.	1130	instead have been omitted.
981		1131
982	Another common scenario is having some data structure with multiple	1132	Another common scenario is to use some data structure with multiple
983	watchers:	1133	embedded watchers:
984		1134
985	struct my_biggy	1135	struct my_biggy
986	{	1136	{
987	int some_data;	1137	int some_data;
988	ev_timer t1;	1138	ev_timer t1;
989	ev_timer t2;	1139	ev_timer t2;
990	}	1140	}
991		1141
992	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1142	In this case getting the pointer to C<my_biggy> is a bit more
993	you need to use C<offsetof>:	1143	complicated: Either you store the address of your C<my_biggy> struct
		1144	in the C<data> member of the watcher (for woozies), or you need to use
		1145	some pointer arithmetic using C<offsetof> inside your watchers (for real
		1146	programmers):
994		1147
995	#include <stddef.h>	1148	#include <stddef.h>
996		1149
997	static void	1150	static void
998	t1_cb (EV_P_ struct ev_timer *w, int revents)	1151	t1_cb (EV_P_ ev_timer *w, int revents)
999	{	1152	{
1000	struct my_biggy big = (struct my_biggy *	1153	struct my_biggy big = (struct my_biggy *
1001	(((char *)w) - offsetof (struct my_biggy, t1));	1154	(((char *)w) - offsetof (struct my_biggy, t1));
1002	}	1155	}
1003		1156
1004	static void	1157	static void
1005	t2_cb (EV_P_ struct ev_timer *w, int revents)	1158	t2_cb (EV_P_ ev_timer *w, int revents)
1006	{	1159	{
1007	struct my_biggy big = (struct my_biggy *	1160	struct my_biggy big = (struct my_biggy *
1008	(((char *)w) - offsetof (struct my_biggy, t2));	1161	(((char *)w) - offsetof (struct my_biggy, t2));
1009	}	1162	}
1010		1163
1011		1164
1012	=head1 WATCHER TYPES	1165	=head1 WATCHER TYPES
1013		1166
1014	This section describes each watcher in detail, but will not repeat	1167	This section describes each watcher in detail, but will not repeat
…		…
1038	In general you can register as many read and/or write event watchers per	1191	In general you can register as many read and/or write event watchers per
1039	fd as you want (as long as you don't confuse yourself). Setting all file	1192	fd as you want (as long as you don't confuse yourself). Setting all file
1040	descriptors to non-blocking mode is also usually a good idea (but not	1193	descriptors to non-blocking mode is also usually a good idea (but not
1041	required if you know what you are doing).	1194	required if you know what you are doing).
1042		1195
1043	If you must do this, then force the use of a known-to-be-good backend	1196	If you cannot use non-blocking mode, then force the use of a
1044	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1197	known-to-be-good backend (at the time of this writing, this includes only
1045	C<EVBACKEND_POLL>).	1198	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>).
1046		1199
1047	Another thing you have to watch out for is that it is quite easy to	1200	Another thing you have to watch out for is that it is quite easy to
1048	receive "spurious" readiness notifications, that is your callback might	1201	receive "spurious" readiness notifications, that is your callback might
1049	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1202	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1050	because there is no data. Not only are some backends known to create a	1203	because there is no data. Not only are some backends known to create a
1051	lot of those (for example solaris ports), it is very easy to get into	1204	lot of those (for example Solaris ports), it is very easy to get into
1052	this situation even with a relatively standard program structure. Thus	1205	this situation even with a relatively standard program structure. Thus
1053	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1206	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1054	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1207	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1055		1208
1056	If you cannot run the fd in non-blocking mode (for example you should not	1209	If you cannot run the fd in non-blocking mode (for example you should
1057	play around with an Xlib connection), then you have to seperately re-test	1210	not play around with an Xlib connection), then you have to separately
1058	whether a file descriptor is really ready with a known-to-be good interface	1211	re-test whether a file descriptor is really ready with a known-to-be good
1059	such as poll (fortunately in our Xlib example, Xlib already does this on	1212	interface such as poll (fortunately in our Xlib example, Xlib already
1060	its own, so its quite safe to use).	1213	does this on its own, so its quite safe to use). Some people additionally
		1214	use C<SIGALRM> and an interval timer, just to be sure you won't block
		1215	indefinitely.
		1216
		1217	But really, best use non-blocking mode.
1061		1218
1062	=head3 The special problem of disappearing file descriptors	1219	=head3 The special problem of disappearing file descriptors
1063		1220
1064	Some backends (e.g. kqueue, epoll) need to be told about closing a file	1221	Some backends (e.g. kqueue, epoll) need to be told about closing a file
1065	descriptor (either by calling C<close> explicitly or by any other means,	1222	descriptor (either due to calling C<close> explicitly or any other means,
1066	such as C<dup>). The reason is that you register interest in some file	1223	such as C<dup2>). The reason is that you register interest in some file
1067	descriptor, but when it goes away, the operating system will silently drop	1224	descriptor, but when it goes away, the operating system will silently drop
1068	this interest. If another file descriptor with the same number then is	1225	this interest. If another file descriptor with the same number then is
1069	registered with libev, there is no efficient way to see that this is, in	1226	registered with libev, there is no efficient way to see that this is, in
1070	fact, a different file descriptor.	1227	fact, a different file descriptor.
1071		1228
…		…
1102	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or	1259	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
1103	C<EVBACKEND_POLL>.	1260	C<EVBACKEND_POLL>.
1104		1261
1105	=head3 The special problem of SIGPIPE	1262	=head3 The special problem of SIGPIPE
1106		1263
1107	While not really specific to libev, it is easy to forget about SIGPIPE:	1264	While not really specific to libev, it is easy to forget about C<SIGPIPE>:
1108	when reading from a pipe whose other end has been closed, your program	1265	when writing to a pipe whose other end has been closed, your program gets
1109	gets send a SIGPIPE, which, by default, aborts your program. For most	1266	sent a SIGPIPE, which, by default, aborts your program. For most programs
1110	programs this is sensible behaviour, for daemons, this is usually	1267	this is sensible behaviour, for daemons, this is usually undesirable.
1111	undesirable.
1112		1268
1113	So when you encounter spurious, unexplained daemon exits, make sure you	1269	So when you encounter spurious, unexplained daemon exits, make sure you
1114	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1270	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1115	somewhere, as that would have given you a big clue).	1271	somewhere, as that would have given you a big clue).
1116		1272
…		…
1122	=item ev_io_init (ev_io *, callback, int fd, int events)	1278	=item ev_io_init (ev_io *, callback, int fd, int events)
1123		1279
1124	=item ev_io_set (ev_io *, int fd, int events)	1280	=item ev_io_set (ev_io *, int fd, int events)
1125		1281
1126	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1282	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1127	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1283	receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or
1128	C<EV_READ | EV_WRITE> to receive the given events.	1284	C<EV_READ | EV_WRITE>, to express the desire to receive the given events.
1129		1285
1130	=item int fd [read-only]	1286	=item int fd [read-only]
1131		1287
1132	The file descriptor being watched.	1288	The file descriptor being watched.
1133		1289
…		…
1141		1297
1142	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1298	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1143	readable, but only once. Since it is likely line-buffered, you could	1299	readable, but only once. Since it is likely line-buffered, you could
1144	attempt to read a whole line in the callback.	1300	attempt to read a whole line in the callback.
1145		1301
1146	static void	1302	static void
1147	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1303	stdin_readable_cb (struct ev_loop *loop, ev_io *w, int revents)
1148	{	1304	{
1149	ev_io_stop (loop, w);	1305	ev_io_stop (loop, w);
1150	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1306	.. read from stdin here (or from w->fd) and handle any I/O errors
1151	}	1307	}
1152		1308
1153	...	1309	...
1154	struct ev_loop *loop = ev_default_init (0);	1310	struct ev_loop *loop = ev_default_init (0);
1155	struct ev_io stdin_readable;	1311	ev_io stdin_readable;
1156	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1312	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1157	ev_io_start (loop, &stdin_readable);	1313	ev_io_start (loop, &stdin_readable);
1158	ev_loop (loop, 0);	1314	ev_loop (loop, 0);
1159		1315
1160		1316
1161	=head2 C<ev_timer> - relative and optionally repeating timeouts	1317	=head2 C<ev_timer> - relative and optionally repeating timeouts
1162		1318
1163	Timer watchers are simple relative timers that generate an event after a	1319	Timer watchers are simple relative timers that generate an event after a
1164	given time, and optionally repeating in regular intervals after that.	1320	given time, and optionally repeating in regular intervals after that.
1165		1321
1166	The timers are based on real time, that is, if you register an event that	1322	The timers are based on real time, that is, if you register an event that
1167	times out after an hour and you reset your system clock to january last	1323	times out after an hour and you reset your system clock to January last
1168	year, it will still time out after (roughly) and hour. "Roughly" because	1324	year, it will still time out after (roughly) one hour. "Roughly" because
1169	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1325	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1170	monotonic clock option helps a lot here).	1326	monotonic clock option helps a lot here).
		1327
		1328	The callback is guaranteed to be invoked only I<after> its timeout has
		1329	passed, but if multiple timers become ready during the same loop iteration
		1330	then order of execution is undefined.
		1331
		1332	=head3 Be smart about timeouts
		1333
		1334	Many real-world problems involve some kind of timeout, usually for error
		1335	recovery. A typical example is an HTTP request - if the other side hangs,
		1336	you want to raise some error after a while.
		1337
		1338	What follows are some ways to handle this problem, from obvious and
		1339	inefficient to smart and efficient.
		1340
		1341	In the following, a 60 second activity timeout is assumed - a timeout that
		1342	gets reset to 60 seconds each time there is activity (e.g. each time some
		1343	data or other life sign was received).
		1344
		1345	=over 4
		1346
		1347	=item 1. Use a timer and stop, reinitialise and start it on activity.
		1348
		1349	This is the most obvious, but not the most simple way: In the beginning,
		1350	start the watcher:
		1351
		1352	ev_timer_init (timer, callback, 60., 0.);
		1353	ev_timer_start (loop, timer);
		1354
		1355	Then, each time there is some activity, C<ev_timer_stop> it, initialise it
		1356	and start it again:
		1357
		1358	ev_timer_stop (loop, timer);
		1359	ev_timer_set (timer, 60., 0.);
		1360	ev_timer_start (loop, timer);
		1361
		1362	This is relatively simple to implement, but means that each time there is
		1363	some activity, libev will first have to remove the timer from its internal
		1364	data structure and then add it again. Libev tries to be fast, but it's
		1365	still not a constant-time operation.
		1366
		1367	=item 2. Use a timer and re-start it with C<ev_timer_again> inactivity.
		1368
		1369	This is the easiest way, and involves using C<ev_timer_again> instead of
		1370	C<ev_timer_start>.
		1371
		1372	To implement this, configure an C<ev_timer> with a C<repeat> value
		1373	of C<60> and then call C<ev_timer_again> at start and each time you
		1374	successfully read or write some data. If you go into an idle state where
		1375	you do not expect data to travel on the socket, you can C<ev_timer_stop>
		1376	the timer, and C<ev_timer_again> will automatically restart it if need be.
		1377
		1378	That means you can ignore both the C<ev_timer_start> function and the
		1379	C<after> argument to C<ev_timer_set>, and only ever use the C<repeat>
		1380	member and C<ev_timer_again>.
		1381
		1382	At start:
		1383
		1384	ev_timer_init (timer, callback);
		1385	timer->repeat = 60.;
		1386	ev_timer_again (loop, timer);
		1387
		1388	Each time there is some activity:
		1389
		1390	ev_timer_again (loop, timer);
		1391
		1392	It is even possible to change the time-out on the fly, regardless of
		1393	whether the watcher is active or not:
		1394
		1395	timer->repeat = 30.;
		1396	ev_timer_again (loop, timer);
		1397
		1398	This is slightly more efficient then stopping/starting the timer each time
		1399	you want to modify its timeout value, as libev does not have to completely
		1400	remove and re-insert the timer from/into its internal data structure.
		1401
		1402	It is, however, even simpler than the "obvious" way to do it.
		1403
		1404	=item 3. Let the timer time out, but then re-arm it as required.
		1405
		1406	This method is more tricky, but usually most efficient: Most timeouts are
		1407	relatively long compared to the intervals between other activity - in
		1408	our example, within 60 seconds, there are usually many I/O events with
		1409	associated activity resets.
		1410
		1411	In this case, it would be more efficient to leave the C<ev_timer> alone,
		1412	but remember the time of last activity, and check for a real timeout only
		1413	within the callback:
		1414
		1415	ev_tstamp last_activity; // time of last activity
		1416
		1417	static void
		1418	callback (EV_P_ ev_timer *w, int revents)
		1419	{
		1420	ev_tstamp now = ev_now (EV_A);
		1421	ev_tstamp timeout = last_activity + 60.;
		1422
		1423	// if last_activity + 60. is older than now, we did time out
		1424	if (timeout < now)
		1425	{
		1426	// timeout occured, take action
		1427	}
		1428	else
		1429	{
		1430	// callback was invoked, but there was some activity, re-arm
		1431	// the watcher to fire in last_activity + 60, which is
		1432	// guaranteed to be in the future, so "again" is positive:
		1433	w->repeat = timeout - now;
		1434	ev_timer_again (EV_A_ w);
		1435	}
		1436	}
		1437
		1438	To summarise the callback: first calculate the real timeout (defined
		1439	as "60 seconds after the last activity"), then check if that time has
		1440	been reached, which means something I<did>, in fact, time out. Otherwise
		1441	the callback was invoked too early (C<timeout> is in the future), so
		1442	re-schedule the timer to fire at that future time, to see if maybe we have
		1443	a timeout then.
		1444
		1445	Note how C<ev_timer_again> is used, taking advantage of the
		1446	C<ev_timer_again> optimisation when the timer is already running.
		1447
		1448	This scheme causes more callback invocations (about one every 60 seconds
		1449	minus half the average time between activity), but virtually no calls to
		1450	libev to change the timeout.
		1451
		1452	To start the timer, simply initialise the watcher and set C<last_activity>
		1453	to the current time (meaning we just have some activity :), then call the
		1454	callback, which will "do the right thing" and start the timer:
		1455
		1456	ev_timer_init (timer, callback);
		1457	last_activity = ev_now (loop);
		1458	callback (loop, timer, EV_TIMEOUT);
		1459
		1460	And when there is some activity, simply store the current time in
		1461	C<last_activity>, no libev calls at all:
		1462
		1463	last_actiivty = ev_now (loop);
		1464
		1465	This technique is slightly more complex, but in most cases where the
		1466	time-out is unlikely to be triggered, much more efficient.
		1467
		1468	Changing the timeout is trivial as well (if it isn't hard-coded in the
		1469	callback :) - just change the timeout and invoke the callback, which will
		1470	fix things for you.
		1471
		1472	=item 4. Wee, just use a double-linked list for your timeouts.
		1473
		1474	If there is not one request, but many thousands (millions...), all
		1475	employing some kind of timeout with the same timeout value, then one can
		1476	do even better:
		1477
		1478	When starting the timeout, calculate the timeout value and put the timeout
		1479	at the I<end> of the list.
		1480
		1481	Then use an C<ev_timer> to fire when the timeout at the I<beginning> of
		1482	the list is expected to fire (for example, using the technique #3).
		1483
		1484	When there is some activity, remove the timer from the list, recalculate
		1485	the timeout, append it to the end of the list again, and make sure to
		1486	update the C<ev_timer> if it was taken from the beginning of the list.
		1487
		1488	This way, one can manage an unlimited number of timeouts in O(1) time for
		1489	starting, stopping and updating the timers, at the expense of a major
		1490	complication, and having to use a constant timeout. The constant timeout
		1491	ensures that the list stays sorted.
		1492
		1493	=back
		1494
		1495	So which method the best?
		1496
		1497	Method #2 is a simple no-brain-required solution that is adequate in most
		1498	situations. Method #3 requires a bit more thinking, but handles many cases
		1499	better, and isn't very complicated either. In most case, choosing either
		1500	one is fine, with #3 being better in typical situations.
		1501
		1502	Method #1 is almost always a bad idea, and buys you nothing. Method #4 is
		1503	rather complicated, but extremely efficient, something that really pays
		1504	off after the first million or so of active timers, i.e. it's usually
		1505	overkill :)
		1506
		1507	=head3 The special problem of time updates
		1508
		1509	Establishing the current time is a costly operation (it usually takes at
		1510	least two system calls): EV therefore updates its idea of the current
		1511	time only before and after C<ev_loop> collects new events, which causes a
		1512	growing difference between C<ev_now ()> and C<ev_time ()> when handling
		1513	lots of events in one iteration.
1171		1514
1172	The relative timeouts are calculated relative to the C<ev_now ()>	1515	The relative timeouts are calculated relative to the C<ev_now ()>
1173	time. This is usually the right thing as this timestamp refers to the time	1516	time. This is usually the right thing as this timestamp refers to the time
1174	of the event triggering whatever timeout you are modifying/starting. If	1517	of the event triggering whatever timeout you are modifying/starting. If
1175	you suspect event processing to be delayed and you I<need> to base the timeout	1518	you suspect event processing to be delayed and you I<need> to base the
1176	on the current time, use something like this to adjust for this:	1519	timeout on the current time, use something like this to adjust for this:
1177		1520
1178	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1521	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1179		1522
1180	The callback is guarenteed to be invoked only after its timeout has passed,	1523	If the event loop is suspended for a long time, you can also force an
1181	but if multiple timers become ready during the same loop iteration then	1524	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1182	order of execution is undefined.	1525	()>.
1183		1526
1184	=head3 Watcher-Specific Functions and Data Members	1527	=head3 Watcher-Specific Functions and Data Members
1185		1528
1186	=over 4	1529	=over 4
1187		1530
…		…
1206	This will act as if the timer timed out and restart it again if it is	1549	This will act as if the timer timed out and restart it again if it is
1207	repeating. The exact semantics are:	1550	repeating. The exact semantics are:
1208		1551
1209	If the timer is pending, its pending status is cleared.	1552	If the timer is pending, its pending status is cleared.
1210		1553
1211	If the timer is started but nonrepeating, stop it (as if it timed out).	1554	If the timer is started but non-repeating, stop it (as if it timed out).
1212		1555
1213	If the timer is repeating, either start it if necessary (with the	1556	If the timer is repeating, either start it if necessary (with the
1214	C<repeat> value), or reset the running timer to the C<repeat> value.	1557	C<repeat> value), or reset the running timer to the C<repeat> value.
1215		1558
1216	This sounds a bit complicated, but here is a useful and typical	1559	This sounds a bit complicated, see "Be smart about timeouts", above, for a
1217	example: Imagine you have a tcp connection and you want a so-called idle	1560	usage example.
1218	timeout, that is, you want to be called when there have been, say, 60
1219	seconds of inactivity on the socket. The easiest way to do this is to
1220	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1221	C<ev_timer_again> each time you successfully read or write some data. If
1222	you go into an idle state where you do not expect data to travel on the
1223	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
1224	automatically restart it if need be.
1225
1226	That means you can ignore the C<after> value and C<ev_timer_start>
1227	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
1228
1229	ev_timer_init (timer, callback, 0., 5.);
1230	ev_timer_again (loop, timer);
1231	...
1232	timer->again = 17.;
1233	ev_timer_again (loop, timer);
1234	...
1235	timer->again = 10.;
1236	ev_timer_again (loop, timer);
1237
1238	This is more slightly efficient then stopping/starting the timer each time
1239	you want to modify its timeout value.
1240		1561
1241	=item ev_tstamp repeat [read-write]	1562	=item ev_tstamp repeat [read-write]
1242		1563
1243	The current C<repeat> value. Will be used each time the watcher times out	1564	The current C<repeat> value. Will be used each time the watcher times out
1244	or C<ev_timer_again> is called and determines the next timeout (if any),	1565	or C<ev_timer_again> is called, and determines the next timeout (if any),
1245	which is also when any modifications are taken into account.	1566	which is also when any modifications are taken into account.
1246		1567
1247	=back	1568	=back
1248		1569
1249	=head3 Examples	1570	=head3 Examples
1250		1571
1251	Example: Create a timer that fires after 60 seconds.	1572	Example: Create a timer that fires after 60 seconds.
1252		1573
1253	static void	1574	static void
1254	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1575	one_minute_cb (struct ev_loop *loop, ev_timer *w, int revents)
1255	{	1576	{
1256	.. one minute over, w is actually stopped right here	1577	.. one minute over, w is actually stopped right here
1257	}	1578	}
1258		1579
1259	struct ev_timer mytimer;	1580	ev_timer mytimer;
1260	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1581	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1261	ev_timer_start (loop, &mytimer);	1582	ev_timer_start (loop, &mytimer);
1262		1583
1263	Example: Create a timeout timer that times out after 10 seconds of	1584	Example: Create a timeout timer that times out after 10 seconds of
1264	inactivity.	1585	inactivity.
1265		1586
1266	static void	1587	static void
1267	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1588	timeout_cb (struct ev_loop *loop, ev_timer *w, int revents)
1268	{	1589	{
1269	.. ten seconds without any activity	1590	.. ten seconds without any activity
1270	}	1591	}
1271		1592
1272	struct ev_timer mytimer;	1593	ev_timer mytimer;
1273	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1594	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1274	ev_timer_again (&mytimer); /* start timer */	1595	ev_timer_again (&mytimer); /* start timer */
1275	ev_loop (loop, 0);	1596	ev_loop (loop, 0);
1276		1597
1277	// and in some piece of code that gets executed on any "activity":	1598	// and in some piece of code that gets executed on any "activity":
1278	// reset the timeout to start ticking again at 10 seconds	1599	// reset the timeout to start ticking again at 10 seconds
1279	ev_timer_again (&mytimer);	1600	ev_timer_again (&mytimer);
1280		1601
1281		1602
1282	=head2 C<ev_periodic> - to cron or not to cron?	1603	=head2 C<ev_periodic> - to cron or not to cron?
1283		1604
1284	Periodic watchers are also timers of a kind, but they are very versatile	1605	Periodic watchers are also timers of a kind, but they are very versatile
1285	(and unfortunately a bit complex).	1606	(and unfortunately a bit complex).
1286		1607
1287	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1608	Unlike C<ev_timer>, periodic watchers are not based on real time (or
1288	but on wallclock time (absolute time). You can tell a periodic watcher	1609	relative time, the physical time that passes) but on wall clock time
1289	to trigger after some specific point in time. For example, if you tell a	1610	(absolute time, the thing you can read on your calender or clock). The
1290	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1611	difference is that wall clock time can run faster or slower than real
1291	+ 10.>, that is, an absolute time not a delay) and then reset your system	1612	time, and time jumps are not uncommon (e.g. when you adjust your
1292	clock to january of the previous year, then it will take more than year	1613	wrist-watch).
1293	to trigger the event (unlike an C<ev_timer>, which would still trigger
1294	roughly 10 seconds later as it uses a relative timeout).
1295		1614
		1615	You can tell a periodic watcher to trigger after some specific point
		1616	in time: for example, if you tell a periodic watcher to trigger "in 10
		1617	seconds" (by specifying e.g. C<ev_now () + 10.>, that is, an absolute time
		1618	not a delay) and then reset your system clock to January of the previous
		1619	year, then it will take a year or more to trigger the event (unlike an
		1620	C<ev_timer>, which would still trigger roughly 10 seconds after starting
		1621	it, as it uses a relative timeout).
		1622
1296	C<ev_periodic>s can also be used to implement vastly more complex timers,	1623	C<ev_periodic> watchers can also be used to implement vastly more complex
1297	such as triggering an event on each "midnight, local time", or other	1624	timers, such as triggering an event on each "midnight, local time", or
1298	complicated, rules.	1625	other complicated rules. This cannot be done with C<ev_timer> watchers, as
		1626	those cannot react to time jumps.
1299		1627
1300	As with timers, the callback is guarenteed to be invoked only when the	1628	As with timers, the callback is guaranteed to be invoked only when the
1301	time (C<at>) has passed, but if multiple periodic timers become ready	1629	point in time where it is supposed to trigger has passed, but if multiple
1302	during the same loop iteration then order of execution is undefined.	1630	periodic timers become ready during the same loop iteration, then order of
		1631	execution is undefined.
1303		1632
1304	=head3 Watcher-Specific Functions and Data Members	1633	=head3 Watcher-Specific Functions and Data Members
1305		1634
1306	=over 4	1635	=over 4
1307		1636
1308	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1637	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)
1309		1638
1310	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1639	=item ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)
1311		1640
1312	Lots of arguments, lets sort it out... There are basically three modes of	1641	Lots of arguments, let's sort it out... There are basically three modes of
1313	operation, and we will explain them from simplest to complex:	1642	operation, and we will explain them from simplest to most complex:
1314		1643
1315	=over 4	1644	=over 4
1316		1645
1317	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1646	=item * absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0)
1318		1647
1319	In this configuration the watcher triggers an event after the wallclock	1648	In this configuration the watcher triggers an event after the wall clock
1320	time C<at> has passed and doesn't repeat. It will not adjust when a time	1649	time C<offset> has passed. It will not repeat and will not adjust when a
1321	jump occurs, that is, if it is to be run at January 1st 2011 then it will	1650	time jump occurs, that is, if it is to be run at January 1st 2011 then it
1322	run when the system time reaches or surpasses this time.	1651	will be stopped and invoked when the system clock reaches or surpasses
		1652	this point in time.
1323		1653
1324	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1654	=item * repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0)
1325		1655
1326	In this mode the watcher will always be scheduled to time out at the next	1656	In this mode the watcher will always be scheduled to time out at the next
1327	C<at + N * interval> time (for some integer N, which can also be negative)	1657	C<offset + N * interval> time (for some integer N, which can also be
1328	and then repeat, regardless of any time jumps.	1658	negative) and then repeat, regardless of any time jumps. The C<offset>
		1659	argument is merely an offset into the C<interval> periods.
1329		1660
1330	This can be used to create timers that do not drift with respect to system	1661	This can be used to create timers that do not drift with respect to the
1331	time, for example, here is a C<ev_periodic> that triggers each hour, on	1662	system clock, for example, here is an C<ev_periodic> that triggers each
1332	the hour:	1663	hour, on the hour (with respect to UTC):
1333		1664
1334	ev_periodic_set (&periodic, 0., 3600., 0);	1665	ev_periodic_set (&periodic, 0., 3600., 0);
1335		1666
1336	This doesn't mean there will always be 3600 seconds in between triggers,	1667	This doesn't mean there will always be 3600 seconds in between triggers,
1337	but only that the the callback will be called when the system time shows a	1668	but only that the callback will be called when the system time shows a
1338	full hour (UTC), or more correctly, when the system time is evenly divisible	1669	full hour (UTC), or more correctly, when the system time is evenly divisible
1339	by 3600.	1670	by 3600.
1340		1671
1341	Another way to think about it (for the mathematically inclined) is that	1672	Another way to think about it (for the mathematically inclined) is that
1342	C<ev_periodic> will try to run the callback in this mode at the next possible	1673	C<ev_periodic> will try to run the callback in this mode at the next possible
1343	time where C<time = at (mod interval)>, regardless of any time jumps.	1674	time where C<time = offset (mod interval)>, regardless of any time jumps.
1344		1675
1345	For numerical stability it is preferable that the C<at> value is near	1676	For numerical stability it is preferable that the C<offset> value is near
1346	C<ev_now ()> (the current time), but there is no range requirement for	1677	C<ev_now ()> (the current time), but there is no range requirement for
1347	this value, and in fact is often specified as zero.	1678	this value, and in fact is often specified as zero.
1348		1679
1349	Note also that there is an upper limit to how often a timer can fire (cpu	1680	Note also that there is an upper limit to how often a timer can fire (CPU
1350	speed for example), so if C<interval> is very small then timing stability	1681	speed for example), so if C<interval> is very small then timing stability
1351	will of course detoriate. Libev itself tries to be exact to be about one	1682	will of course deteriorate. Libev itself tries to be exact to be about one
1352	millisecond (if the OS supports it and the machine is fast enough).	1683	millisecond (if the OS supports it and the machine is fast enough).
1353		1684
1354	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1685	=item * manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback)
1355		1686
1356	In this mode the values for C<interval> and C<at> are both being	1687	In this mode the values for C<interval> and C<offset> are both being
1357	ignored. Instead, each time the periodic watcher gets scheduled, the	1688	ignored. Instead, each time the periodic watcher gets scheduled, the
1358	reschedule callback will be called with the watcher as first, and the	1689	reschedule callback will be called with the watcher as first, and the
1359	current time as second argument.	1690	current time as second argument.
1360		1691
1361	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1692	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, ever,
1362	ever, or make ANY event loop modifications whatsoever>.	1693	or make ANY other event loop modifications whatsoever, unless explicitly
		1694	allowed by documentation here>.
1363		1695
1364	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop	1696	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
1365	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the	1697	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
1366	only event loop modification you are allowed to do).	1698	only event loop modification you are allowed to do).
1367		1699
1368	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic	1700	The callback prototype is C<ev_tstamp (*reschedule_cb)(ev_periodic
1369	*w, ev_tstamp now)>, e.g.:	1701	*w, ev_tstamp now)>, e.g.:
1370		1702
		1703	static ev_tstamp
1371	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1704	my_rescheduler (ev_periodic *w, ev_tstamp now)
1372	{	1705	{
1373	return now + 60.;	1706	return now + 60.;
1374	}	1707	}
1375		1708
1376	It must return the next time to trigger, based on the passed time value	1709	It must return the next time to trigger, based on the passed time value
…		…
1396	a different time than the last time it was called (e.g. in a crond like	1729	a different time than the last time it was called (e.g. in a crond like
1397	program when the crontabs have changed).	1730	program when the crontabs have changed).
1398		1731
1399	=item ev_tstamp ev_periodic_at (ev_periodic *)	1732	=item ev_tstamp ev_periodic_at (ev_periodic *)
1400		1733
1401	When active, returns the absolute time that the watcher is supposed to	1734	When active, returns the absolute time that the watcher is supposed
1402	trigger next.	1735	to trigger next. This is not the same as the C<offset> argument to
		1736	C<ev_periodic_set>, but indeed works even in interval and manual
		1737	rescheduling modes.
1403		1738
1404	=item ev_tstamp offset [read-write]	1739	=item ev_tstamp offset [read-write]
1405		1740
1406	When repeating, this contains the offset value, otherwise this is the	1741	When repeating, this contains the offset value, otherwise this is the
1407	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1742	absolute point in time (the C<offset> value passed to C<ev_periodic_set>,
		1743	although libev might modify this value for better numerical stability).
1408		1744
1409	Can be modified any time, but changes only take effect when the periodic	1745	Can be modified any time, but changes only take effect when the periodic
1410	timer fires or C<ev_periodic_again> is being called.	1746	timer fires or C<ev_periodic_again> is being called.
1411		1747
1412	=item ev_tstamp interval [read-write]	1748	=item ev_tstamp interval [read-write]
1413		1749
1414	The current interval value. Can be modified any time, but changes only	1750	The current interval value. Can be modified any time, but changes only
1415	take effect when the periodic timer fires or C<ev_periodic_again> is being	1751	take effect when the periodic timer fires or C<ev_periodic_again> is being
1416	called.	1752	called.
1417		1753
1418	=item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]	1754	=item ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read-write]
1419		1755
1420	The current reschedule callback, or C<0>, if this functionality is	1756	The current reschedule callback, or C<0>, if this functionality is
1421	switched off. Can be changed any time, but changes only take effect when	1757	switched off. Can be changed any time, but changes only take effect when
1422	the periodic timer fires or C<ev_periodic_again> is being called.	1758	the periodic timer fires or C<ev_periodic_again> is being called.
1423		1759
1424	=back	1760	=back
1425		1761
1426	=head3 Examples	1762	=head3 Examples
1427		1763
1428	Example: Call a callback every hour, or, more precisely, whenever the	1764	Example: Call a callback every hour, or, more precisely, whenever the
1429	system clock is divisible by 3600. The callback invocation times have	1765	system time is divisible by 3600. The callback invocation times have
1430	potentially a lot of jittering, but good long-term stability.	1766	potentially a lot of jitter, but good long-term stability.
1431		1767
1432	static void	1768	static void
1433	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1769	clock_cb (struct ev_loop *loop, ev_io *w, int revents)
1434	{	1770	{
1435	... its now a full hour (UTC, or TAI or whatever your clock follows)	1771	... its now a full hour (UTC, or TAI or whatever your clock follows)
1436	}	1772	}
1437		1773
1438	struct ev_periodic hourly_tick;	1774	ev_periodic hourly_tick;
1439	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1775	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1440	ev_periodic_start (loop, &hourly_tick);	1776	ev_periodic_start (loop, &hourly_tick);
1441		1777
1442	Example: The same as above, but use a reschedule callback to do it:	1778	Example: The same as above, but use a reschedule callback to do it:
1443		1779
1444	#include <math.h>	1780	#include <math.h>
1445		1781
1446	static ev_tstamp	1782	static ev_tstamp
1447	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1783	my_scheduler_cb (ev_periodic *w, ev_tstamp now)
1448	{	1784	{
1449	return fmod (now, 3600.) + 3600.;	1785	return now + (3600. - fmod (now, 3600.));
1450	}	1786	}
1451		1787
1452	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1788	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1453		1789
1454	Example: Call a callback every hour, starting now:	1790	Example: Call a callback every hour, starting now:
1455		1791
1456	struct ev_periodic hourly_tick;	1792	ev_periodic hourly_tick;
1457	ev_periodic_init (&hourly_tick, clock_cb,	1793	ev_periodic_init (&hourly_tick, clock_cb,
1458	fmod (ev_now (loop), 3600.), 3600., 0);	1794	fmod (ev_now (loop), 3600.), 3600., 0);
1459	ev_periodic_start (loop, &hourly_tick);	1795	ev_periodic_start (loop, &hourly_tick);
1460		1796
1461		1797
1462	=head2 C<ev_signal> - signal me when a signal gets signalled!	1798	=head2 C<ev_signal> - signal me when a signal gets signalled!
1463		1799
1464	Signal watchers will trigger an event when the process receives a specific	1800	Signal watchers will trigger an event when the process receives a specific
1465	signal one or more times. Even though signals are very asynchronous, libev	1801	signal one or more times. Even though signals are very asynchronous, libev
1466	will try it's best to deliver signals synchronously, i.e. as part of the	1802	will try it's best to deliver signals synchronously, i.e. as part of the
1467	normal event processing, like any other event.	1803	normal event processing, like any other event.
1468		1804
		1805	If you want signals asynchronously, just use C<sigaction> as you would
		1806	do without libev and forget about sharing the signal. You can even use
		1807	C<ev_async> from a signal handler to synchronously wake up an event loop.
		1808
1469	You can configure as many watchers as you like per signal. Only when the	1809	You can configure as many watchers as you like per signal. Only when the
1470	first watcher gets started will libev actually register a signal watcher	1810	first watcher gets started will libev actually register a signal handler
1471	with the kernel (thus it coexists with your own signal handlers as long	1811	with the kernel (thus it coexists with your own signal handlers as long as
1472	as you don't register any with libev). Similarly, when the last signal	1812	you don't register any with libev for the same signal). Similarly, when
1473	watcher for a signal is stopped libev will reset the signal handler to	1813	the last signal watcher for a signal is stopped, libev will reset the
1474	SIG_DFL (regardless of what it was set to before).	1814	signal handler to SIG_DFL (regardless of what it was set to before).
1475		1815
1476	If possible and supported, libev will install its handlers with	1816	If possible and supported, libev will install its handlers with
1477	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1817	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1478	interrupted. If you have a problem with syscalls getting interrupted by	1818	interrupted. If you have a problem with system calls getting interrupted by
1479	signals you can block all signals in an C<ev_check> watcher and unblock	1819	signals you can block all signals in an C<ev_check> watcher and unblock
1480	them in an C<ev_prepare> watcher.	1820	them in an C<ev_prepare> watcher.
1481		1821
1482	=head3 Watcher-Specific Functions and Data Members	1822	=head3 Watcher-Specific Functions and Data Members
1483		1823
…		…
1496		1836
1497	=back	1837	=back
1498		1838
1499	=head3 Examples	1839	=head3 Examples
1500		1840
1501	Example: Try to exit cleanly on SIGINT and SIGTERM.	1841	Example: Try to exit cleanly on SIGINT.
1502		1842
1503	static void	1843	static void
1504	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1844	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
1505	{	1845	{
1506	ev_unloop (loop, EVUNLOOP_ALL);	1846	ev_unloop (loop, EVUNLOOP_ALL);
1507	}	1847	}
1508		1848
1509	struct ev_signal signal_watcher;	1849	ev_signal signal_watcher;
1510	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1850	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1511	ev_signal_start (loop, &sigint_cb);	1851	ev_signal_start (loop, &signal_watcher);
1512		1852
1513		1853
1514	=head2 C<ev_child> - watch out for process status changes	1854	=head2 C<ev_child> - watch out for process status changes
1515		1855
1516	Child watchers trigger when your process receives a SIGCHLD in response to	1856	Child watchers trigger when your process receives a SIGCHLD in response to
1517	some child status changes (most typically when a child of yours dies). It	1857	some child status changes (most typically when a child of yours dies or
1518	is permissible to install a child watcher I<after> the child has been	1858	exits). It is permissible to install a child watcher I<after> the child
1519	forked (which implies it might have already exited), as long as the event	1859	has been forked (which implies it might have already exited), as long
1520	loop isn't entered (or is continued from a watcher).	1860	as the event loop isn't entered (or is continued from a watcher), i.e.,
		1861	forking and then immediately registering a watcher for the child is fine,
		1862	but forking and registering a watcher a few event loop iterations later is
		1863	not.
1521		1864
1522	Only the default event loop is capable of handling signals, and therefore	1865	Only the default event loop is capable of handling signals, and therefore
1523	you can only rgeister child watchers in the default event loop.	1866	you can only register child watchers in the default event loop.
1524		1867
1525	=head3 Process Interaction	1868	=head3 Process Interaction
1526		1869
1527	Libev grabs C<SIGCHLD> as soon as the default event loop is	1870	Libev grabs C<SIGCHLD> as soon as the default event loop is
1528	initialised. This is necessary to guarantee proper behaviour even if	1871	initialised. This is necessary to guarantee proper behaviour even if
1529	the first child watcher is started after the child exits. The occurance	1872	the first child watcher is started after the child exits. The occurrence
1530	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1873	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1531	synchronously as part of the event loop processing. Libev always reaps all	1874	synchronously as part of the event loop processing. Libev always reaps all
1532	children, even ones not watched.	1875	children, even ones not watched.
1533		1876
1534	=head3 Overriding the Built-In Processing	1877	=head3 Overriding the Built-In Processing
…		…
1538	handler, you can override it easily by installing your own handler for	1881	handler, you can override it easily by installing your own handler for
1539	C<SIGCHLD> after initialising the default loop, and making sure the	1882	C<SIGCHLD> after initialising the default loop, and making sure the
1540	default loop never gets destroyed. You are encouraged, however, to use an	1883	default loop never gets destroyed. You are encouraged, however, to use an
1541	event-based approach to child reaping and thus use libev's support for	1884	event-based approach to child reaping and thus use libev's support for
1542	that, so other libev users can use C<ev_child> watchers freely.	1885	that, so other libev users can use C<ev_child> watchers freely.
		1886
		1887	=head3 Stopping the Child Watcher
		1888
		1889	Currently, the child watcher never gets stopped, even when the
		1890	child terminates, so normally one needs to stop the watcher in the
		1891	callback. Future versions of libev might stop the watcher automatically
		1892	when a child exit is detected.
1543		1893
1544	=head3 Watcher-Specific Functions and Data Members	1894	=head3 Watcher-Specific Functions and Data Members
1545		1895
1546	=over 4	1896	=over 4
1547		1897
…		…
1576	=head3 Examples	1926	=head3 Examples
1577		1927
1578	Example: C<fork()> a new process and install a child handler to wait for	1928	Example: C<fork()> a new process and install a child handler to wait for
1579	its completion.	1929	its completion.
1580		1930
1581	ev_child cw;	1931	ev_child cw;
1582		1932
1583	static void	1933	static void
1584	child_cb (EV_P_ struct ev_child *w, int revents)	1934	child_cb (EV_P_ ev_child *w, int revents)
1585	{	1935	{
1586	ev_child_stop (EV_A_ w);	1936	ev_child_stop (EV_A_ w);
1587	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1937	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1588	}	1938	}
1589		1939
1590	pid_t pid = fork ();	1940	pid_t pid = fork ();
1591		1941
1592	if (pid < 0)	1942	if (pid < 0)
1593	// error	1943	// error
1594	else if (pid == 0)	1944	else if (pid == 0)
1595	{	1945	{
1596	// the forked child executes here	1946	// the forked child executes here
1597	exit (1);	1947	exit (1);
1598	}	1948	}
1599	else	1949	else
1600	{	1950	{
1601	ev_child_init (&cw, child_cb, pid, 0);	1951	ev_child_init (&cw, child_cb, pid, 0);
1602	ev_child_start (EV_DEFAULT_ &cw);	1952	ev_child_start (EV_DEFAULT_ &cw);
1603	}	1953	}
1604		1954
1605		1955
1606	=head2 C<ev_stat> - did the file attributes just change?	1956	=head2 C<ev_stat> - did the file attributes just change?
1607		1957
1608	This watches a filesystem path for attribute changes. That is, it calls	1958	This watches a file system path for attribute changes. That is, it calls
1609	C<stat> regularly (or when the OS says it changed) and sees if it changed	1959	C<stat> on that path in regular intervals (or when the OS says it changed)
1610	compared to the last time, invoking the callback if it did.	1960	and sees if it changed compared to the last time, invoking the callback if
		1961	it did.
1611		1962
1612	The path does not need to exist: changing from "path exists" to "path does	1963	The path does not need to exist: changing from "path exists" to "path does
1613	not exist" is a status change like any other. The condition "path does	1964	not exist" is a status change like any other. The condition "path does not
1614	not exist" is signified by the C<st_nlink> field being zero (which is	1965	exist" (or more correctly "path cannot be stat'ed") is signified by the
1615	otherwise always forced to be at least one) and all the other fields of	1966	C<st_nlink> field being zero (which is otherwise always forced to be at
1616	the stat buffer having unspecified contents.	1967	least one) and all the other fields of the stat buffer having unspecified
		1968	contents.
1617		1969
1618	The path I<should> be absolute and I<must not> end in a slash. If it is	1970	The path I<must not> end in a slash or contain special components such as
		1971	C<.> or C<..>. The path I<should> be absolute: If it is relative and
1619	relative and your working directory changes, the behaviour is undefined.	1972	your working directory changes, then the behaviour is undefined.
1620		1973
1621	Since there is no standard to do this, the portable implementation simply	1974	Since there is no portable change notification interface available, the
1622	calls C<stat (2)> regularly on the path to see if it changed somehow. You	1975	portable implementation simply calls C<stat(2)> regularly on the path
1623	can specify a recommended polling interval for this case. If you specify	1976	to see if it changed somehow. You can specify a recommended polling
1624	a polling interval of C<0> (highly recommended!) then a I<suitable,	1977	interval for this case. If you specify a polling interval of C<0> (highly
1625	unspecified default> value will be used (which you can expect to be around	1978	recommended!) then a I<suitable, unspecified default> value will be used
1626	five seconds, although this might change dynamically). Libev will also	1979	(which you can expect to be around five seconds, although this might
1627	impose a minimum interval which is currently around C<0.1>, but thats	1980	change dynamically). Libev will also impose a minimum interval which is
1628	usually overkill.	1981	currently around C<0.1>, but that's usually overkill.
1629		1982
1630	This watcher type is not meant for massive numbers of stat watchers,	1983	This watcher type is not meant for massive numbers of stat watchers,
1631	as even with OS-supported change notifications, this can be	1984	as even with OS-supported change notifications, this can be
1632	resource-intensive.	1985	resource-intensive.
1633		1986
1634	At the time of this writing, only the Linux inotify interface is	1987	At the time of this writing, the only OS-specific interface implemented
1635	implemented (implementing kqueue support is left as an exercise for the	1988	is the Linux inotify interface (implementing kqueue support is left as an
1636	reader, note, however, that the author sees no way of implementing ev_stat	1989	exercise for the reader. Note, however, that the author sees no way of
1637	semantics with kqueue). Inotify will be used to give hints only and should	1990	implementing C<ev_stat> semantics with kqueue, except as a hint).
1638	not change the semantics of C<ev_stat> watchers, which means that libev
1639	sometimes needs to fall back to regular polling again even with inotify,
1640	but changes are usually detected immediately, and if the file exists there
1641	will be no polling.
1642		1991
1643	=head3 ABI Issues (Largefile Support)	1992	=head3 ABI Issues (Largefile Support)
1644		1993
1645	Libev by default (unless the user overrides this) uses the default	1994	Libev by default (unless the user overrides this) uses the default
1646	compilation environment, which means that on systems with optionally	1995	compilation environment, which means that on systems with large file
1647	disabled large file support, you get the 32 bit version of the stat	1996	support disabled by default, you get the 32 bit version of the stat
1648	structure. When using the library from programs that change the ABI to	1997	structure. When using the library from programs that change the ABI to
1649	use 64 bit file offsets the programs will fail. In that case you have to	1998	use 64 bit file offsets the programs will fail. In that case you have to
1650	compile libev with the same flags to get binary compatibility. This is	1999	compile libev with the same flags to get binary compatibility. This is
1651	obviously the case with any flags that change the ABI, but the problem is	2000	obviously the case with any flags that change the ABI, but the problem is
1652	most noticably with ev_stat and largefile support.	2001	most noticeably displayed with ev_stat and large file support.
1653		2002
1654	=head3 Inotify	2003	The solution for this is to lobby your distribution maker to make large
		2004	file interfaces available by default (as e.g. FreeBSD does) and not
		2005	optional. Libev cannot simply switch on large file support because it has
		2006	to exchange stat structures with application programs compiled using the
		2007	default compilation environment.
1655		2008
		2009	=head3 Inotify and Kqueue
		2010
1656	When C<inotify (7)> support has been compiled into libev (generally only	2011	When C<inotify (7)> support has been compiled into libev and present at
1657	available on Linux) and present at runtime, it will be used to speed up	2012	runtime, it will be used to speed up change detection where possible. The
1658	change detection where possible. The inotify descriptor will be created lazily	2013	inotify descriptor will be created lazily when the first C<ev_stat>
1659	when the first C<ev_stat> watcher is being started.	2014	watcher is being started.
1660		2015
1661	Inotify presence does not change the semantics of C<ev_stat> watchers	2016	Inotify presence does not change the semantics of C<ev_stat> watchers
1662	except that changes might be detected earlier, and in some cases, to avoid	2017	except that changes might be detected earlier, and in some cases, to avoid
1663	making regular C<stat> calls. Even in the presence of inotify support	2018	making regular C<stat> calls. Even in the presence of inotify support
1664	there are many cases where libev has to resort to regular C<stat> polling.	2019	there are many cases where libev has to resort to regular C<stat> polling,
		2020	but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too
		2021	many bugs), the path exists (i.e. stat succeeds), and the path resides on
		2022	a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and
		2023	xfs are fully working) libev usually gets away without polling.
1665		2024
1666	(There is no support for kqueue, as apparently it cannot be used to	2025	There is no support for kqueue, as apparently it cannot be used to
1667	implement this functionality, due to the requirement of having a file	2026	implement this functionality, due to the requirement of having a file
1668	descriptor open on the object at all times).	2027	descriptor open on the object at all times, and detecting renames, unlinks
		2028	etc. is difficult.
		2029
		2030	=head3 C<stat ()> is a synchronous operation
		2031
		2032	Libev doesn't normally do any kind of I/O itself, and so is not blocking
		2033	the process. The exception are C<ev_stat> watchers - those call C<stat
		2034	()>, which is a synchronous operation.
		2035
		2036	For local paths, this usually doesn't matter: unless the system is very
		2037	busy or the intervals between stat's are large, a stat call will be fast,
		2038	as the path data is usually in memory already (except when starting the
		2039	watcher).
		2040
		2041	For networked file systems, calling C<stat ()> can block an indefinite
		2042	time due to network issues, and even under good conditions, a stat call
		2043	often takes multiple milliseconds.
		2044
		2045	Therefore, it is best to avoid using C<ev_stat> watchers on networked
		2046	paths, although this is fully supported by libev.
1669		2047
1670	=head3 The special problem of stat time resolution	2048	=head3 The special problem of stat time resolution
1671		2049
1672	The C<stat ()> syscall only supports full-second resolution portably, and	2050	The C<stat ()> system call only supports full-second resolution portably,
1673	even on systems where the resolution is higher, many filesystems still	2051	and even on systems where the resolution is higher, most file systems
1674	only support whole seconds.	2052	still only support whole seconds.
1675		2053
1676	That means that, if the time is the only thing that changes, you can	2054	That means that, if the time is the only thing that changes, you can
1677	easily miss updates: on the first update, C<ev_stat> detects a change and	2055	easily miss updates: on the first update, C<ev_stat> detects a change and
1678	calls your callback, which does something. When there is another update	2056	calls your callback, which does something. When there is another update
1679	within the same second, C<ev_stat> will be unable to detect it as the stat	2057	within the same second, C<ev_stat> will be unable to detect unless the
1680	data does not change.	2058	stat data does change in other ways (e.g. file size).
1681		2059
1682	The solution to this is to delay acting on a change for slightly more	2060	The solution to this is to delay acting on a change for slightly more
1683	than a second (or till slightly after the next full second boundary), using	2061	than a second (or till slightly after the next full second boundary), using
1684	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);	2062	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1685	ev_timer_again (loop, w)>).	2063	ev_timer_again (loop, w)>).
…		…
1705	C<path>. The C<interval> is a hint on how quickly a change is expected to	2083	C<path>. The C<interval> is a hint on how quickly a change is expected to
1706	be detected and should normally be specified as C<0> to let libev choose	2084	be detected and should normally be specified as C<0> to let libev choose
1707	a suitable value. The memory pointed to by C<path> must point to the same	2085	a suitable value. The memory pointed to by C<path> must point to the same
1708	path for as long as the watcher is active.	2086	path for as long as the watcher is active.
1709		2087
1710	The callback will receive C<EV_STAT> when a change was detected, relative	2088	The callback will receive an C<EV_STAT> event when a change was detected,
1711	to the attributes at the time the watcher was started (or the last change	2089	relative to the attributes at the time the watcher was started (or the
1712	was detected).	2090	last change was detected).
1713		2091
1714	=item ev_stat_stat (loop, ev_stat *)	2092	=item ev_stat_stat (loop, ev_stat *)
1715		2093
1716	Updates the stat buffer immediately with new values. If you change the	2094	Updates the stat buffer immediately with new values. If you change the
1717	watched path in your callback, you could call this function to avoid	2095	watched path in your callback, you could call this function to avoid
…		…
1738		2116
1739	The specified interval.	2117	The specified interval.
1740		2118
1741	=item const char *path [read-only]	2119	=item const char *path [read-only]
1742		2120
1743	The filesystem path that is being watched.	2121	The file system path that is being watched.
1744		2122
1745	=back	2123	=back
1746		2124
1747	=head3 Examples	2125	=head3 Examples
1748		2126
1749	Example: Watch C</etc/passwd> for attribute changes.	2127	Example: Watch C</etc/passwd> for attribute changes.
1750		2128
1751	static void	2129	static void
1752	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	2130	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1753	{	2131	{
1754	/* /etc/passwd changed in some way */	2132	/* /etc/passwd changed in some way */
1755	if (w->attr.st_nlink)	2133	if (w->attr.st_nlink)
1756	{	2134	{
1757	printf ("passwd current size %ld\n", (long)w->attr.st_size);	2135	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1758	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	2136	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1759	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	2137	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1760	}	2138	}
1761	else	2139	else
1762	/* you shalt not abuse printf for puts */	2140	/* you shalt not abuse printf for puts */
1763	puts ("wow, /etc/passwd is not there, expect problems. "	2141	puts ("wow, /etc/passwd is not there, expect problems. "
1764	"if this is windows, they already arrived\n");	2142	"if this is windows, they already arrived\n");
1765	}	2143	}
1766		2144
1767	...	2145	...
1768	ev_stat passwd;	2146	ev_stat passwd;
1769		2147
1770	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	2148	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1771	ev_stat_start (loop, &passwd);	2149	ev_stat_start (loop, &passwd);
1772		2150
1773	Example: Like above, but additionally use a one-second delay so we do not	2151	Example: Like above, but additionally use a one-second delay so we do not
1774	miss updates (however, frequent updates will delay processing, too, so	2152	miss updates (however, frequent updates will delay processing, too, so
1775	one might do the work both on C<ev_stat> callback invocation I<and> on	2153	one might do the work both on C<ev_stat> callback invocation I<and> on
1776	C<ev_timer> callback invocation).	2154	C<ev_timer> callback invocation).
1777		2155
1778	static ev_stat passwd;	2156	static ev_stat passwd;
1779	static ev_timer timer;	2157	static ev_timer timer;
1780		2158
1781	static void	2159	static void
1782	timer_cb (EV_P_ ev_timer *w, int revents)	2160	timer_cb (EV_P_ ev_timer *w, int revents)
1783	{	2161	{
1784	ev_timer_stop (EV_A_ w);	2162	ev_timer_stop (EV_A_ w);
1785		2163
1786	/* now it's one second after the most recent passwd change */	2164	/* now it's one second after the most recent passwd change */
1787	}	2165	}
1788		2166
1789	static void	2167	static void
1790	stat_cb (EV_P_ ev_stat *w, int revents)	2168	stat_cb (EV_P_ ev_stat *w, int revents)
1791	{	2169	{
1792	/* reset the one-second timer */	2170	/* reset the one-second timer */
1793	ev_timer_again (EV_A_ &timer);	2171	ev_timer_again (EV_A_ &timer);
1794	}	2172	}
1795		2173
1796	...	2174	...
1797	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	2175	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1798	ev_stat_start (loop, &passwd);	2176	ev_stat_start (loop, &passwd);
1799	ev_timer_init (&timer, timer_cb, 0., 1.02);	2177	ev_timer_init (&timer, timer_cb, 0., 1.02);
1800		2178
1801		2179
1802	=head2 C<ev_idle> - when you've got nothing better to do...	2180	=head2 C<ev_idle> - when you've got nothing better to do...
1803		2181
1804	Idle watchers trigger events when no other events of the same or higher	2182	Idle watchers trigger events when no other events of the same or higher
1805	priority are pending (prepare, check and other idle watchers do not	2183	priority are pending (prepare, check and other idle watchers do not count
1806	count).	2184	as receiving "events").
1807		2185
1808	That is, as long as your process is busy handling sockets or timeouts	2186	That is, as long as your process is busy handling sockets or timeouts
1809	(or even signals, imagine) of the same or higher priority it will not be	2187	(or even signals, imagine) of the same or higher priority it will not be
1810	triggered. But when your process is idle (or only lower-priority watchers	2188	triggered. But when your process is idle (or only lower-priority watchers
1811	are pending), the idle watchers are being called once per event loop	2189	are pending), the idle watchers are being called once per event loop
…		…
1822		2200
1823	=head3 Watcher-Specific Functions and Data Members	2201	=head3 Watcher-Specific Functions and Data Members
1824		2202
1825	=over 4	2203	=over 4
1826		2204
1827	=item ev_idle_init (ev_signal *, callback)	2205	=item ev_idle_init (ev_idle *, callback)
1828		2206
1829	Initialises and configures the idle watcher - it has no parameters of any	2207	Initialises and configures the idle watcher - it has no parameters of any
1830	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	2208	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1831	believe me.	2209	believe me.
1832		2210
…		…
1835	=head3 Examples	2213	=head3 Examples
1836		2214
1837	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	2215	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1838	callback, free it. Also, use no error checking, as usual.	2216	callback, free it. Also, use no error checking, as usual.
1839		2217
1840	static void	2218	static void
1841	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	2219	idle_cb (struct ev_loop *loop, ev_idle *w, int revents)
1842	{	2220	{
1843	free (w);	2221	free (w);
1844	// now do something you wanted to do when the program has	2222	// now do something you wanted to do when the program has
1845	// no longer anything immediate to do.	2223	// no longer anything immediate to do.
1846	}	2224	}
1847		2225
1848	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	2226	ev_idle *idle_watcher = malloc (sizeof (ev_idle));
1849	ev_idle_init (idle_watcher, idle_cb);	2227	ev_idle_init (idle_watcher, idle_cb);
1850	ev_idle_start (loop, idle_cb);	2228	ev_idle_start (loop, idle_cb);
1851		2229
1852		2230
1853	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	2231	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1854		2232
1855	Prepare and check watchers are usually (but not always) used in tandem:	2233	Prepare and check watchers are usually (but not always) used in pairs:
1856	prepare watchers get invoked before the process blocks and check watchers	2234	prepare watchers get invoked before the process blocks and check watchers
1857	afterwards.	2235	afterwards.
1858		2236
1859	You I<must not> call C<ev_loop> or similar functions that enter	2237	You I<must not> call C<ev_loop> or similar functions that enter
1860	the current event loop from either C<ev_prepare> or C<ev_check>	2238	the current event loop from either C<ev_prepare> or C<ev_check>
…		…
1863	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2241	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
1864	C<ev_check> so if you have one watcher of each kind they will always be	2242	C<ev_check> so if you have one watcher of each kind they will always be
1865	called in pairs bracketing the blocking call.	2243	called in pairs bracketing the blocking call.
1866		2244
1867	Their main purpose is to integrate other event mechanisms into libev and	2245	Their main purpose is to integrate other event mechanisms into libev and
1868	their use is somewhat advanced. This could be used, for example, to track	2246	their use is somewhat advanced. They could be used, for example, to track
1869	variable changes, implement your own watchers, integrate net-snmp or a	2247	variable changes, implement your own watchers, integrate net-snmp or a
1870	coroutine library and lots more. They are also occasionally useful if	2248	coroutine library and lots more. They are also occasionally useful if
1871	you cache some data and want to flush it before blocking (for example,	2249	you cache some data and want to flush it before blocking (for example,
1872	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>	2250	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
1873	watcher).	2251	watcher).
1874		2252
1875	This is done by examining in each prepare call which file descriptors need	2253	This is done by examining in each prepare call which file descriptors
1876	to be watched by the other library, registering C<ev_io> watchers for	2254	need to be watched by the other library, registering C<ev_io> watchers
1877	them and starting an C<ev_timer> watcher for any timeouts (many libraries	2255	for them and starting an C<ev_timer> watcher for any timeouts (many
1878	provide just this functionality). Then, in the check watcher you check for	2256	libraries provide exactly this functionality). Then, in the check watcher,
1879	any events that occured (by checking the pending status of all watchers	2257	you check for any events that occurred (by checking the pending status
1880	and stopping them) and call back into the library. The I/O and timer	2258	of all watchers and stopping them) and call back into the library. The
1881	callbacks will never actually be called (but must be valid nevertheless,	2259	I/O and timer callbacks will never actually be called (but must be valid
1882	because you never know, you know?).	2260	nevertheless, because you never know, you know?).
1883		2261
1884	As another example, the Perl Coro module uses these hooks to integrate	2262	As another example, the Perl Coro module uses these hooks to integrate
1885	coroutines into libev programs, by yielding to other active coroutines	2263	coroutines into libev programs, by yielding to other active coroutines
1886	during each prepare and only letting the process block if no coroutines	2264	during each prepare and only letting the process block if no coroutines
1887	are ready to run (it's actually more complicated: it only runs coroutines	2265	are ready to run (it's actually more complicated: it only runs coroutines
…		…
1890	loop from blocking if lower-priority coroutines are active, thus mapping	2268	loop from blocking if lower-priority coroutines are active, thus mapping
1891	low-priority coroutines to idle/background tasks).	2269	low-priority coroutines to idle/background tasks).
1892		2270
1893	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	2271	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1894	priority, to ensure that they are being run before any other watchers	2272	priority, to ensure that they are being run before any other watchers
		2273	after the poll (this doesn't matter for C<ev_prepare> watchers).
		2274
1895	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	2275	Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not
1896	too) should not activate ("feed") events into libev. While libev fully	2276	activate ("feed") events into libev. While libev fully supports this, they
1897	supports this, they might get executed before other C<ev_check> watchers	2277	might get executed before other C<ev_check> watchers did their job. As
1898	did their job. As C<ev_check> watchers are often used to embed other	2278	C<ev_check> watchers are often used to embed other (non-libev) event
1899	(non-libev) event loops those other event loops might be in an unusable	2279	loops those other event loops might be in an unusable state until their
1900	state until their C<ev_check> watcher ran (always remind yourself to	2280	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
1901	coexist peacefully with others).	2281	others).
1902		2282
1903	=head3 Watcher-Specific Functions and Data Members	2283	=head3 Watcher-Specific Functions and Data Members
1904		2284
1905	=over 4	2285	=over 4
1906		2286
…		…
1908		2288
1909	=item ev_check_init (ev_check *, callback)	2289	=item ev_check_init (ev_check *, callback)
1910		2290
1911	Initialises and configures the prepare or check watcher - they have no	2291	Initialises and configures the prepare or check watcher - they have no
1912	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	2292	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1913	macros, but using them is utterly, utterly and completely pointless.	2293	macros, but using them is utterly, utterly, utterly and completely
		2294	pointless.
1914		2295
1915	=back	2296	=back
1916		2297
1917	=head3 Examples	2298	=head3 Examples
1918		2299
…		…
1927	and in a check watcher, destroy them and call into libadns. What follows	2308	and in a check watcher, destroy them and call into libadns. What follows
1928	is pseudo-code only of course. This requires you to either use a low	2309	is pseudo-code only of course. This requires you to either use a low
1929	priority for the check watcher or use C<ev_clear_pending> explicitly, as	2310	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1930	the callbacks for the IO/timeout watchers might not have been called yet.	2311	the callbacks for the IO/timeout watchers might not have been called yet.
1931		2312
1932	static ev_io iow [nfd];	2313	static ev_io iow [nfd];
1933	static ev_timer tw;	2314	static ev_timer tw;
1934		2315
1935	static void	2316	static void
1936	io_cb (ev_loop *loop, ev_io *w, int revents)	2317	io_cb (struct ev_loop *loop, ev_io *w, int revents)
1937	{	2318	{
1938	}	2319	}
1939		2320
1940	// create io watchers for each fd and a timer before blocking	2321	// create io watchers for each fd and a timer before blocking
1941	static void	2322	static void
1942	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	2323	adns_prepare_cb (struct ev_loop *loop, ev_prepare *w, int revents)
1943	{	2324	{
1944	int timeout = 3600000;	2325	int timeout = 3600000;
1945	struct pollfd fds [nfd];	2326	struct pollfd fds [nfd];
1946	// actual code will need to loop here and realloc etc.	2327	// actual code will need to loop here and realloc etc.
1947	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	2328	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1948		2329
1949	/* the callback is illegal, but won't be called as we stop during check */	2330	/* the callback is illegal, but won't be called as we stop during check */
1950	ev_timer_init (&tw, 0, timeout * 1e-3);	2331	ev_timer_init (&tw, 0, timeout * 1e-3);
1951	ev_timer_start (loop, &tw);	2332	ev_timer_start (loop, &tw);
1952		2333
1953	// create one ev_io per pollfd	2334	// create one ev_io per pollfd
1954	for (int i = 0; i < nfd; ++i)	2335	for (int i = 0; i < nfd; ++i)
1955	{	2336	{
1956	ev_io_init (iow + i, io_cb, fds [i].fd,	2337	ev_io_init (iow + i, io_cb, fds [i].fd,
1957	((fds [i].events & POLLIN ? EV_READ : 0)	2338	((fds [i].events & POLLIN ? EV_READ : 0)
1958	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	2339	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1959		2340
1960	fds [i].revents = 0;	2341	fds [i].revents = 0;
1961	ev_io_start (loop, iow + i);	2342	ev_io_start (loop, iow + i);
1962	}	2343	}
1963	}	2344	}
1964		2345
1965	// stop all watchers after blocking	2346	// stop all watchers after blocking
1966	static void	2347	static void
1967	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	2348	adns_check_cb (struct ev_loop *loop, ev_check *w, int revents)
1968	{	2349	{
1969	ev_timer_stop (loop, &tw);	2350	ev_timer_stop (loop, &tw);
1970		2351
1971	for (int i = 0; i < nfd; ++i)	2352	for (int i = 0; i < nfd; ++i)
1972	{	2353	{
1973	// set the relevant poll flags	2354	// set the relevant poll flags
1974	// could also call adns_processreadable etc. here	2355	// could also call adns_processreadable etc. here
1975	struct pollfd *fd = fds + i;	2356	struct pollfd *fd = fds + i;
1976	int revents = ev_clear_pending (iow + i);	2357	int revents = ev_clear_pending (iow + i);
1977	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2358	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1978	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2359	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1979		2360
1980	// now stop the watcher	2361	// now stop the watcher
1981	ev_io_stop (loop, iow + i);	2362	ev_io_stop (loop, iow + i);
1982	}	2363	}
1983		2364
1984	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2365	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1985	}	2366	}
1986		2367
1987	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2368	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1988	in the prepare watcher and would dispose of the check watcher.	2369	in the prepare watcher and would dispose of the check watcher.
1989		2370
1990	Method 3: If the module to be embedded supports explicit event	2371	Method 3: If the module to be embedded supports explicit event
1991	notification (adns does), you can also make use of the actual watcher	2372	notification (libadns does), you can also make use of the actual watcher
1992	callbacks, and only destroy/create the watchers in the prepare watcher.	2373	callbacks, and only destroy/create the watchers in the prepare watcher.
1993		2374
1994	static void	2375	static void
1995	timer_cb (EV_P_ ev_timer *w, int revents)	2376	timer_cb (EV_P_ ev_timer *w, int revents)
1996	{	2377	{
1997	adns_state ads = (adns_state)w->data;	2378	adns_state ads = (adns_state)w->data;
1998	update_now (EV_A);	2379	update_now (EV_A);
1999		2380
2000	adns_processtimeouts (ads, &tv_now);	2381	adns_processtimeouts (ads, &tv_now);
2001	}	2382	}
2002		2383
2003	static void	2384	static void
2004	io_cb (EV_P_ ev_io *w, int revents)	2385	io_cb (EV_P_ ev_io *w, int revents)
2005	{	2386	{
2006	adns_state ads = (adns_state)w->data;	2387	adns_state ads = (adns_state)w->data;
2007	update_now (EV_A);	2388	update_now (EV_A);
2008		2389
2009	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2390	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
2010	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2391	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
2011	}	2392	}
2012		2393
2013	// do not ever call adns_afterpoll	2394	// do not ever call adns_afterpoll
2014		2395
2015	Method 4: Do not use a prepare or check watcher because the module you	2396	Method 4: Do not use a prepare or check watcher because the module you
2016	want to embed is too inflexible to support it. Instead, youc na override	2397	want to embed is not flexible enough to support it. Instead, you can
2017	their poll function. The drawback with this solution is that the main	2398	override their poll function. The drawback with this solution is that the
2018	loop is now no longer controllable by EV. The C<Glib::EV> module does	2399	main loop is now no longer controllable by EV. The C<Glib::EV> module uses
2019	this.	2400	this approach, effectively embedding EV as a client into the horrible
		2401	libglib event loop.
2020		2402
2021	static gint	2403	static gint
2022	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2404	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
2023	{	2405	{
2024	int got_events = 0;	2406	int got_events = 0;
2025		2407
2026	for (n = 0; n < nfds; ++n)	2408	for (n = 0; n < nfds; ++n)
2027	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2409	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
2028		2410
2029	if (timeout >= 0)	2411	if (timeout >= 0)
2030	// create/start timer	2412	// create/start timer
2031		2413
2032	// poll	2414	// poll
2033	ev_loop (EV_A_ 0);	2415	ev_loop (EV_A_ 0);
2034		2416
2035	// stop timer again	2417	// stop timer again
2036	if (timeout >= 0)	2418	if (timeout >= 0)
2037	ev_timer_stop (EV_A_ &to);	2419	ev_timer_stop (EV_A_ &to);
2038		2420
2039	// stop io watchers again - their callbacks should have set	2421	// stop io watchers again - their callbacks should have set
2040	for (n = 0; n < nfds; ++n)	2422	for (n = 0; n < nfds; ++n)
2041	ev_io_stop (EV_A_ iow [n]);	2423	ev_io_stop (EV_A_ iow [n]);
2042		2424
2043	return got_events;	2425	return got_events;
2044	}	2426	}
2045		2427
2046		2428
2047	=head2 C<ev_embed> - when one backend isn't enough...	2429	=head2 C<ev_embed> - when one backend isn't enough...
2048		2430
2049	This is a rather advanced watcher type that lets you embed one event loop	2431	This is a rather advanced watcher type that lets you embed one event loop
…		…
2055	prioritise I/O.	2437	prioritise I/O.
2056		2438
2057	As an example for a bug workaround, the kqueue backend might only support	2439	As an example for a bug workaround, the kqueue backend might only support
2058	sockets on some platform, so it is unusable as generic backend, but you	2440	sockets on some platform, so it is unusable as generic backend, but you
2059	still want to make use of it because you have many sockets and it scales	2441	still want to make use of it because you have many sockets and it scales
2060	so nicely. In this case, you would create a kqueue-based loop and embed it	2442	so nicely. In this case, you would create a kqueue-based loop and embed
2061	into your default loop (which might use e.g. poll). Overall operation will	2443	it into your default loop (which might use e.g. poll). Overall operation
2062	be a bit slower because first libev has to poll and then call kevent, but	2444	will be a bit slower because first libev has to call C<poll> and then
2063	at least you can use both at what they are best.	2445	C<kevent>, but at least you can use both mechanisms for what they are
		2446	best: C<kqueue> for scalable sockets and C<poll> if you want it to work :)
2064		2447
2065	As for prioritising I/O: rarely you have the case where some fds have	2448	As for prioritising I/O: under rare circumstances you have the case where
2066	to be watched and handled very quickly (with low latency), and even	2449	some fds have to be watched and handled very quickly (with low latency),
2067	priorities and idle watchers might have too much overhead. In this case	2450	and even priorities and idle watchers might have too much overhead. In
2068	you would put all the high priority stuff in one loop and all the rest in	2451	this case you would put all the high priority stuff in one loop and all
2069	a second one, and embed the second one in the first.	2452	the rest in a second one, and embed the second one in the first.
2070		2453
2071	As long as the watcher is active, the callback will be invoked every time	2454	As long as the watcher is active, the callback will be invoked every
2072	there might be events pending in the embedded loop. The callback must then	2455	time there might be events pending in the embedded loop. The callback
2073	call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke	2456	must then call C<ev_embed_sweep (mainloop, watcher)> to make a single
2074	their callbacks (you could also start an idle watcher to give the embedded	2457	sweep and invoke their callbacks (the callback doesn't need to invoke the
2075	loop strictly lower priority for example). You can also set the callback	2458	C<ev_embed_sweep> function directly, it could also start an idle watcher
2076	to C<0>, in which case the embed watcher will automatically execute the	2459	to give the embedded loop strictly lower priority for example).
2077	embedded loop sweep.
2078		2460
2079	As long as the watcher is started it will automatically handle events. The	2461	You can also set the callback to C<0>, in which case the embed watcher
2080	callback will be invoked whenever some events have been handled. You can	2462	will automatically execute the embedded loop sweep whenever necessary.
2081	set the callback to C<0> to avoid having to specify one if you are not
2082	interested in that.
2083		2463
2084	Also, there have not currently been made special provisions for forking:	2464	Fork detection will be handled transparently while the C<ev_embed> watcher
2085	when you fork, you not only have to call C<ev_loop_fork> on both loops,	2465	is active, i.e., the embedded loop will automatically be forked when the
2086	but you will also have to stop and restart any C<ev_embed> watchers	2466	embedding loop forks. In other cases, the user is responsible for calling
2087	yourself.	2467	C<ev_loop_fork> on the embedded loop.
2088		2468
2089	Unfortunately, not all backends are embeddable, only the ones returned by	2469	Unfortunately, not all backends are embeddable: only the ones returned by
2090	C<ev_embeddable_backends> are, which, unfortunately, does not include any	2470	C<ev_embeddable_backends> are, which, unfortunately, does not include any
2091	portable one.	2471	portable one.
2092		2472
2093	So when you want to use this feature you will always have to be prepared	2473	So when you want to use this feature you will always have to be prepared
2094	that you cannot get an embeddable loop. The recommended way to get around	2474	that you cannot get an embeddable loop. The recommended way to get around
2095	this is to have a separate variables for your embeddable loop, try to	2475	this is to have a separate variables for your embeddable loop, try to
2096	create it, and if that fails, use the normal loop for everything.	2476	create it, and if that fails, use the normal loop for everything.
2097		2477
		2478	=head3 C<ev_embed> and fork
		2479
		2480	While the C<ev_embed> watcher is running, forks in the embedding loop will
		2481	automatically be applied to the embedded loop as well, so no special
		2482	fork handling is required in that case. When the watcher is not running,
		2483	however, it is still the task of the libev user to call C<ev_loop_fork ()>
		2484	as applicable.
		2485
2098	=head3 Watcher-Specific Functions and Data Members	2486	=head3 Watcher-Specific Functions and Data Members
2099		2487
2100	=over 4	2488	=over 4
2101		2489
2102	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)	2490	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
…		…
2105		2493
2106	Configures the watcher to embed the given loop, which must be	2494	Configures the watcher to embed the given loop, which must be
2107	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	2495	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
2108	invoked automatically, otherwise it is the responsibility of the callback	2496	invoked automatically, otherwise it is the responsibility of the callback
2109	to invoke it (it will continue to be called until the sweep has been done,	2497	to invoke it (it will continue to be called until the sweep has been done,
2110	if you do not want thta, you need to temporarily stop the embed watcher).	2498	if you do not want that, you need to temporarily stop the embed watcher).
2111		2499
2112	=item ev_embed_sweep (loop, ev_embed *)	2500	=item ev_embed_sweep (loop, ev_embed *)
2113		2501
2114	Make a single, non-blocking sweep over the embedded loop. This works	2502	Make a single, non-blocking sweep over the embedded loop. This works
2115	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2503	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2116	apropriate way for embedded loops.	2504	appropriate way for embedded loops.
2117		2505
2118	=item struct ev_loop *other [read-only]	2506	=item struct ev_loop *other [read-only]
2119		2507
2120	The embedded event loop.	2508	The embedded event loop.
2121		2509
…		…
2123		2511
2124	=head3 Examples	2512	=head3 Examples
2125		2513
2126	Example: Try to get an embeddable event loop and embed it into the default	2514	Example: Try to get an embeddable event loop and embed it into the default
2127	event loop. If that is not possible, use the default loop. The default	2515	event loop. If that is not possible, use the default loop. The default
2128	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2516	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2129	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2517	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2130	used).	2518	used).
2131		2519
2132	struct ev_loop *loop_hi = ev_default_init (0);	2520	struct ev_loop *loop_hi = ev_default_init (0);
2133	struct ev_loop *loop_lo = 0;	2521	struct ev_loop *loop_lo = 0;
2134	struct ev_embed embed;	2522	ev_embed embed;
2135		2523
2136	// see if there is a chance of getting one that works	2524	// see if there is a chance of getting one that works
2137	// (remember that a flags value of 0 means autodetection)	2525	// (remember that a flags value of 0 means autodetection)
2138	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2526	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2139	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2527	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2140	: 0;	2528	: 0;
2141		2529
2142	// if we got one, then embed it, otherwise default to loop_hi	2530	// if we got one, then embed it, otherwise default to loop_hi
2143	if (loop_lo)	2531	if (loop_lo)
2144	{	2532	{
2145	ev_embed_init (&embed, 0, loop_lo);	2533	ev_embed_init (&embed, 0, loop_lo);
2146	ev_embed_start (loop_hi, &embed);	2534	ev_embed_start (loop_hi, &embed);
2147	}	2535	}
2148	else	2536	else
2149	loop_lo = loop_hi;	2537	loop_lo = loop_hi;
2150		2538
2151	Example: Check if kqueue is available but not recommended and create	2539	Example: Check if kqueue is available but not recommended and create
2152	a kqueue backend for use with sockets (which usually work with any	2540	a kqueue backend for use with sockets (which usually work with any
2153	kqueue implementation). Store the kqueue/socket-only event loop in	2541	kqueue implementation). Store the kqueue/socket-only event loop in
2154	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2542	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2155		2543
2156	struct ev_loop *loop = ev_default_init (0);	2544	struct ev_loop *loop = ev_default_init (0);
2157	struct ev_loop *loop_socket = 0;	2545	struct ev_loop *loop_socket = 0;
2158	struct ev_embed embed;	2546	ev_embed embed;
2159		2547
2160	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2548	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2161	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2549	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2162	{	2550	{
2163	ev_embed_init (&embed, 0, loop_socket);	2551	ev_embed_init (&embed, 0, loop_socket);
2164	ev_embed_start (loop, &embed);	2552	ev_embed_start (loop, &embed);
2165	}	2553	}
2166		2554
2167	if (!loop_socket)	2555	if (!loop_socket)
2168	loop_socket = loop;	2556	loop_socket = loop;
2169		2557
2170	// now use loop_socket for all sockets, and loop for everything else	2558	// now use loop_socket for all sockets, and loop for everything else
2171		2559
2172		2560
2173	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2561	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2174		2562
2175	Fork watchers are called when a C<fork ()> was detected (usually because	2563	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2219	is that the author does not know of a simple (or any) algorithm for a	2607	is that the author does not know of a simple (or any) algorithm for a
2220	multiple-writer-single-reader queue that works in all cases and doesn't	2608	multiple-writer-single-reader queue that works in all cases and doesn't
2221	need elaborate support such as pthreads.	2609	need elaborate support such as pthreads.
2222		2610
2223	That means that if you want to queue data, you have to provide your own	2611	That means that if you want to queue data, you have to provide your own
2224	queue. But at least I can tell you would implement locking around your	2612	queue. But at least I can tell you how to implement locking around your
2225	queue:	2613	queue:
2226		2614
2227	=over 4	2615	=over 4
2228		2616
2229	=item queueing from a signal handler context	2617	=item queueing from a signal handler context
2230		2618
2231	To implement race-free queueing, you simply add to the queue in the signal	2619	To implement race-free queueing, you simply add to the queue in the signal
2232	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2620	handler but you block the signal handler in the watcher callback. Here is
2233	some fictitiuous SIGUSR1 handler:	2621	an example that does that for some fictitious SIGUSR1 handler:
2234		2622
2235	static ev_async mysig;	2623	static ev_async mysig;
2236		2624
2237	static void	2625	static void
2238	sigusr1_handler (void)	2626	sigusr1_handler (void)
…		…
2304	=over 4	2692	=over 4
2305		2693
2306	=item ev_async_init (ev_async *, callback)	2694	=item ev_async_init (ev_async *, callback)
2307		2695
2308	Initialises and configures the async watcher - it has no parameters of any	2696	Initialises and configures the async watcher - it has no parameters of any
2309	kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless,	2697	kind. There is a C<ev_async_set> macro, but using it is utterly pointless,
2310	believe me.	2698	trust me.
2311		2699
2312	=item ev_async_send (loop, ev_async *)	2700	=item ev_async_send (loop, ev_async *)
2313		2701
2314	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2702	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2315	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2703	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2316	C<ev_feed_event>, this call is safe to do in other threads, signal or	2704	C<ev_feed_event>, this call is safe to do from other threads, signal or
2317	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2705	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2318	section below on what exactly this means).	2706	section below on what exactly this means).
2319		2707
		2708	Note that, as with other watchers in libev, multiple events might get
		2709	compressed into a single callback invocation (another way to look at this
		2710	is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>,
		2711	reset when the event loop detects that).
		2712
2320	This call incurs the overhead of a syscall only once per loop iteration,	2713	This call incurs the overhead of a system call only once per event loop
2321	so while the overhead might be noticable, it doesn't apply to repeated	2714	iteration, so while the overhead might be noticeable, it doesn't apply to
2322	calls to C<ev_async_send>.	2715	repeated calls to C<ev_async_send> for the same event loop.
2323		2716
2324	=item bool = ev_async_pending (ev_async *)	2717	=item bool = ev_async_pending (ev_async *)
2325		2718
2326	Returns a non-zero value when C<ev_async_send> has been called on the	2719	Returns a non-zero value when C<ev_async_send> has been called on the
2327	watcher but the event has not yet been processed (or even noted) by the	2720	watcher but the event has not yet been processed (or even noted) by the
2328	event loop.	2721	event loop.
2329		2722
2330	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When	2723	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2331	the loop iterates next and checks for the watcher to have become active,	2724	the loop iterates next and checks for the watcher to have become active,
2332	it will reset the flag again. C<ev_async_pending> can be used to very	2725	it will reset the flag again. C<ev_async_pending> can be used to very
2333	quickly check wether invoking the loop might be a good idea.	2726	quickly check whether invoking the loop might be a good idea.
2334		2727
2335	Not that this does I<not> check wether the watcher itself is pending, only	2728	Not that this does I<not> check whether the watcher itself is pending,
2336	wether it has been requested to make this watcher pending.	2729	only whether it has been requested to make this watcher pending: there
		2730	is a time window between the event loop checking and resetting the async
		2731	notification, and the callback being invoked.
2337		2732
2338	=back	2733	=back
2339		2734
2340		2735
2341	=head1 OTHER FUNCTIONS	2736	=head1 OTHER FUNCTIONS
…		…
2345	=over 4	2740	=over 4
2346		2741
2347	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)	2742	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)
2348		2743
2349	This function combines a simple timer and an I/O watcher, calls your	2744	This function combines a simple timer and an I/O watcher, calls your
2350	callback on whichever event happens first and automatically stop both	2745	callback on whichever event happens first and automatically stops both
2351	watchers. This is useful if you want to wait for a single event on an fd	2746	watchers. This is useful if you want to wait for a single event on an fd
2352	or timeout without having to allocate/configure/start/stop/free one or	2747	or timeout without having to allocate/configure/start/stop/free one or
2353	more watchers yourself.	2748	more watchers yourself.
2354		2749
2355	If C<fd> is less than 0, then no I/O watcher will be started and events	2750	If C<fd> is less than 0, then no I/O watcher will be started and the
2356	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2751	C<events> argument is being ignored. Otherwise, an C<ev_io> watcher for
2357	C<events> set will be craeted and started.	2752	the given C<fd> and C<events> set will be created and started.
2358		2753
2359	If C<timeout> is less than 0, then no timeout watcher will be	2754	If C<timeout> is less than 0, then no timeout watcher will be
2360	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2755	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2361	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2756	repeat = 0) will be started. C<0> is a valid timeout.
2362	dubious value.
2363		2757
2364	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2758	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2365	passed an C<revents> set like normal event callbacks (a combination of	2759	passed an C<revents> set like normal event callbacks (a combination of
2366	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2760	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2367	value passed to C<ev_once>:	2761	value passed to C<ev_once>. Note that it is possible to receive I<both>
		2762	a timeout and an io event at the same time - you probably should give io
		2763	events precedence.
2368		2764
		2765	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
		2766
2369	static void stdin_ready (int revents, void *arg)	2767	static void stdin_ready (int revents, void *arg)
2370	{	2768	{
2371	if (revents & EV_TIMEOUT)
2372	/* doh, nothing entered */;
2373	else if (revents & EV_READ)	2769	if (revents & EV_READ)
2374	/* stdin might have data for us, joy! */;	2770	/* stdin might have data for us, joy! */;
		2771	else if (revents & EV_TIMEOUT)
		2772	/* doh, nothing entered */;
2375	}	2773	}
2376		2774
2377	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2775	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2378		2776
2379	=item ev_feed_event (ev_loop *, watcher *, int revents)	2777	=item ev_feed_event (struct ev_loop *, watcher *, int revents)
2380		2778
2381	Feeds the given event set into the event loop, as if the specified event	2779	Feeds the given event set into the event loop, as if the specified event
2382	had happened for the specified watcher (which must be a pointer to an	2780	had happened for the specified watcher (which must be a pointer to an
2383	initialised but not necessarily started event watcher).	2781	initialised but not necessarily started event watcher).
2384		2782
2385	=item ev_feed_fd_event (ev_loop *, int fd, int revents)	2783	=item ev_feed_fd_event (struct ev_loop *, int fd, int revents)
2386		2784
2387	Feed an event on the given fd, as if a file descriptor backend detected	2785	Feed an event on the given fd, as if a file descriptor backend detected
2388	the given events it.	2786	the given events it.
2389		2787
2390	=item ev_feed_signal_event (ev_loop *loop, int signum)	2788	=item ev_feed_signal_event (struct ev_loop *loop, int signum)
2391		2789
2392	Feed an event as if the given signal occured (C<loop> must be the default	2790	Feed an event as if the given signal occurred (C<loop> must be the default
2393	loop!).	2791	loop!).
2394		2792
2395	=back	2793	=back
2396		2794
2397		2795
…		…
2426	=back	2824	=back
2427		2825
2428	=head1 C++ SUPPORT	2826	=head1 C++ SUPPORT
2429		2827
2430	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2828	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2431	you to use some convinience methods to start/stop watchers and also change	2829	you to use some convenience methods to start/stop watchers and also change
2432	the callback model to a model using method callbacks on objects.	2830	the callback model to a model using method callbacks on objects.
2433		2831
2434	To use it,	2832	To use it,
2435		2833
2436	#include <ev++.h>	2834	#include <ev++.h>
2437		2835
2438	This automatically includes F<ev.h> and puts all of its definitions (many	2836	This automatically includes F<ev.h> and puts all of its definitions (many
2439	of them macros) into the global namespace. All C++ specific things are	2837	of them macros) into the global namespace. All C++ specific things are
2440	put into the C<ev> namespace. It should support all the same embedding	2838	put into the C<ev> namespace. It should support all the same embedding
2441	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2839	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2508	your compiler is good :), then the method will be fully inlined into the	2906	your compiler is good :), then the method will be fully inlined into the
2509	thunking function, making it as fast as a direct C callback.	2907	thunking function, making it as fast as a direct C callback.
2510		2908
2511	Example: simple class declaration and watcher initialisation	2909	Example: simple class declaration and watcher initialisation
2512		2910
2513	struct myclass	2911	struct myclass
2514	{	2912	{
2515	void io_cb (ev::io &w, int revents) { }	2913	void io_cb (ev::io &w, int revents) { }
2516	}	2914	}
2517		2915
2518	myclass obj;	2916	myclass obj;
2519	ev::io iow;	2917	ev::io iow;
2520	iow.set <myclass, &myclass::io_cb> (&obj);	2918	iow.set <myclass, &myclass::io_cb> (&obj);
		2919
		2920	=item w->set (object *)
		2921
		2922	This is an B<experimental> feature that might go away in a future version.
		2923
		2924	This is a variation of a method callback - leaving out the method to call
		2925	will default the method to C<operator ()>, which makes it possible to use
		2926	functor objects without having to manually specify the C<operator ()> all
		2927	the time. Incidentally, you can then also leave out the template argument
		2928	list.
		2929
		2930	The C<operator ()> method prototype must be C<void operator ()(watcher &w,
		2931	int revents)>.
		2932
		2933	See the method-C<set> above for more details.
		2934
		2935	Example: use a functor object as callback.
		2936
		2937	struct myfunctor
		2938	{
		2939	void operator() (ev::io &w, int revents)
		2940	{
		2941	...
		2942	}
		2943	}
		2944
		2945	myfunctor f;
		2946
		2947	ev::io w;
		2948	w.set (&f);
2521		2949
2522	=item w->set<function> (void *data = 0)	2950	=item w->set<function> (void *data = 0)
2523		2951
2524	Also sets a callback, but uses a static method or plain function as	2952	Also sets a callback, but uses a static method or plain function as
2525	callback. The optional C<data> argument will be stored in the watcher's	2953	callback. The optional C<data> argument will be stored in the watcher's
…		…
2527		2955
2528	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.	2956	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
2529		2957
2530	See the method-C<set> above for more details.	2958	See the method-C<set> above for more details.
2531		2959
2532	Example:	2960	Example: Use a plain function as callback.
2533		2961
2534	static void io_cb (ev::io &w, int revents) { }	2962	static void io_cb (ev::io &w, int revents) { }
2535	iow.set <io_cb> ();	2963	iow.set <io_cb> ();
2536		2964
2537	=item w->set (struct ev_loop *)	2965	=item w->set (struct ev_loop *)
2538		2966
2539	Associates a different C<struct ev_loop> with this watcher. You can only	2967	Associates a different C<struct ev_loop> with this watcher. You can only
2540	do this when the watcher is inactive (and not pending either).	2968	do this when the watcher is inactive (and not pending either).
2541		2969
2542	=item w->set ([args])	2970	=item w->set ([arguments])
2543		2971
2544	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2972	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2545	called at least once. Unlike the C counterpart, an active watcher gets	2973	called at least once. Unlike the C counterpart, an active watcher gets
2546	automatically stopped and restarted when reconfiguring it with this	2974	automatically stopped and restarted when reconfiguring it with this
2547	method.	2975	method.
2548		2976
2549	=item w->start ()	2977	=item w->start ()
…		…
2573	=back	3001	=back
2574		3002
2575	Example: Define a class with an IO and idle watcher, start one of them in	3003	Example: Define a class with an IO and idle watcher, start one of them in
2576	the constructor.	3004	the constructor.
2577		3005
2578	class myclass	3006	class myclass
2579	{	3007	{
2580	ev::io io; void io_cb (ev::io &w, int revents);	3008	ev::io io ; void io_cb (ev::io &w, int revents);
2581	ev:idle idle void idle_cb (ev::idle &w, int revents);	3009	ev::idle idle; void idle_cb (ev::idle &w, int revents);
2582		3010
2583	myclass (int fd)	3011	myclass (int fd)
2584	{	3012	{
2585	io .set <myclass, &myclass::io_cb > (this);	3013	io .set <myclass, &myclass::io_cb > (this);
2586	idle.set <myclass, &myclass::idle_cb> (this);	3014	idle.set <myclass, &myclass::idle_cb> (this);
2587		3015
2588	io.start (fd, ev::READ);	3016	io.start (fd, ev::READ);
2589	}	3017	}
2590	};	3018	};
2591		3019
2592		3020
2593	=head1 OTHER LANGUAGE BINDINGS	3021	=head1 OTHER LANGUAGE BINDINGS
2594		3022
2595	Libev does not offer other language bindings itself, but bindings for a	3023	Libev does not offer other language bindings itself, but bindings for a
2596	numbe rof languages exist in the form of third-party packages. If you know	3024	number of languages exist in the form of third-party packages. If you know
2597	any interesting language binding in addition to the ones listed here, drop	3025	any interesting language binding in addition to the ones listed here, drop
2598	me a note.	3026	me a note.
2599		3027
2600	=over 4	3028	=over 4
2601		3029
2602	=item Perl	3030	=item Perl
2603		3031
2604	The EV module implements the full libev API and is actually used to test	3032	The EV module implements the full libev API and is actually used to test
2605	libev. EV is developed together with libev. Apart from the EV core module,	3033	libev. EV is developed together with libev. Apart from the EV core module,
2606	there are additional modules that implement libev-compatible interfaces	3034	there are additional modules that implement libev-compatible interfaces
2607	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	3035	to C<libadns> (C<EV::ADNS>, but C<AnyEvent::DNS> is preferred nowadays),
2608	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	3036	C<Net::SNMP> (C<Net::SNMP::EV>) and the C<libglib> event core (C<Glib::EV>
		3037	and C<EV::Glib>).
2609		3038
2610	It can be found and installed via CPAN, its homepage is found at	3039	It can be found and installed via CPAN, its homepage is at
2611	L<http://software.schmorp.de/pkg/EV>.	3040	L<http://software.schmorp.de/pkg/EV>.
2612		3041
		3042	=item Python
		3043
		3044	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		3045	seems to be quite complete and well-documented.
		3046
2613	=item Ruby	3047	=item Ruby
2614		3048
2615	Tony Arcieri has written a ruby extension that offers access to a subset	3049	Tony Arcieri has written a ruby extension that offers access to a subset
2616	of the libev API and adds filehandle abstractions, asynchronous DNS and	3050	of the libev API and adds file handle abstractions, asynchronous DNS and
2617	more on top of it. It can be found via gem servers. Its homepage is at	3051	more on top of it. It can be found via gem servers. Its homepage is at
2618	L<http://rev.rubyforge.org/>.	3052	L<http://rev.rubyforge.org/>.
2619		3053
		3054	Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190>
		3055	makes rev work even on mingw.
		3056
		3057	=item Haskell
		3058
		3059	A haskell binding to libev is available at
		3060	L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>.
		3061
2620	=item D	3062	=item D
2621		3063
2622	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	3064	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2623	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.	3065	be found at L<http://proj.llucax.com.ar/wiki/evd>.
		3066
		3067	=item Ocaml
		3068
		3069	Erkki Seppala has written Ocaml bindings for libev, to be found at
		3070	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
2624		3071
2625	=back	3072	=back
2626		3073
2627		3074
2628	=head1 MACRO MAGIC	3075	=head1 MACRO MAGIC
2629		3076
2630	Libev can be compiled with a variety of options, the most fundamantal	3077	Libev can be compiled with a variety of options, the most fundamental
2631	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	3078	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2632	functions and callbacks have an initial C<struct ev_loop *> argument.	3079	functions and callbacks have an initial C<struct ev_loop *> argument.
2633		3080
2634	To make it easier to write programs that cope with either variant, the	3081	To make it easier to write programs that cope with either variant, the
2635	following macros are defined:	3082	following macros are defined:
…		…
2640		3087
2641	This provides the loop I<argument> for functions, if one is required ("ev	3088	This provides the loop I<argument> for functions, if one is required ("ev
2642	loop argument"). The C<EV_A> form is used when this is the sole argument,	3089	loop argument"). The C<EV_A> form is used when this is the sole argument,
2643	C<EV_A_> is used when other arguments are following. Example:	3090	C<EV_A_> is used when other arguments are following. Example:
2644		3091
2645	ev_unref (EV_A);	3092	ev_unref (EV_A);
2646	ev_timer_add (EV_A_ watcher);	3093	ev_timer_add (EV_A_ watcher);
2647	ev_loop (EV_A_ 0);	3094	ev_loop (EV_A_ 0);
2648		3095
2649	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3096	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2650	which is often provided by the following macro.	3097	which is often provided by the following macro.
2651		3098
2652	=item C<EV_P>, C<EV_P_>	3099	=item C<EV_P>, C<EV_P_>
2653		3100
2654	This provides the loop I<parameter> for functions, if one is required ("ev	3101	This provides the loop I<parameter> for functions, if one is required ("ev
2655	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	3102	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2656	C<EV_P_> is used when other parameters are following. Example:	3103	C<EV_P_> is used when other parameters are following. Example:
2657		3104
2658	// this is how ev_unref is being declared	3105	// this is how ev_unref is being declared
2659	static void ev_unref (EV_P);	3106	static void ev_unref (EV_P);
2660		3107
2661	// this is how you can declare your typical callback	3108	// this is how you can declare your typical callback
2662	static void cb (EV_P_ ev_timer *w, int revents)	3109	static void cb (EV_P_ ev_timer *w, int revents)
2663		3110
2664	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	3111	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2665	suitable for use with C<EV_A>.	3112	suitable for use with C<EV_A>.
2666		3113
2667	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	3114	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
…		…
2683		3130
2684	Example: Declare and initialise a check watcher, utilising the above	3131	Example: Declare and initialise a check watcher, utilising the above
2685	macros so it will work regardless of whether multiple loops are supported	3132	macros so it will work regardless of whether multiple loops are supported
2686	or not.	3133	or not.
2687		3134
2688	static void	3135	static void
2689	check_cb (EV_P_ ev_timer *w, int revents)	3136	check_cb (EV_P_ ev_timer *w, int revents)
2690	{	3137	{
2691	ev_check_stop (EV_A_ w);	3138	ev_check_stop (EV_A_ w);
2692	}	3139	}
2693		3140
2694	ev_check check;	3141	ev_check check;
2695	ev_check_init (&check, check_cb);	3142	ev_check_init (&check, check_cb);
2696	ev_check_start (EV_DEFAULT_ &check);	3143	ev_check_start (EV_DEFAULT_ &check);
2697	ev_loop (EV_DEFAULT_ 0);	3144	ev_loop (EV_DEFAULT_ 0);
2698		3145
2699	=head1 EMBEDDING	3146	=head1 EMBEDDING
2700		3147
2701	Libev can (and often is) directly embedded into host	3148	Libev can (and often is) directly embedded into host
2702	applications. Examples of applications that embed it include the Deliantra	3149	applications. Examples of applications that embed it include the Deliantra
…		…
2709	libev somewhere in your source tree).	3156	libev somewhere in your source tree).
2710		3157
2711	=head2 FILESETS	3158	=head2 FILESETS
2712		3159
2713	Depending on what features you need you need to include one or more sets of files	3160	Depending on what features you need you need to include one or more sets of files
2714	in your app.	3161	in your application.
2715		3162
2716	=head3 CORE EVENT LOOP	3163	=head3 CORE EVENT LOOP
2717		3164
2718	To include only the libev core (all the C<ev_*> functions), with manual	3165	To include only the libev core (all the C<ev_*> functions), with manual
2719	configuration (no autoconf):	3166	configuration (no autoconf):
2720		3167
2721	#define EV_STANDALONE 1	3168	#define EV_STANDALONE 1
2722	#include "ev.c"	3169	#include "ev.c"
2723		3170
2724	This will automatically include F<ev.h>, too, and should be done in a	3171	This will automatically include F<ev.h>, too, and should be done in a
2725	single C source file only to provide the function implementations. To use	3172	single C source file only to provide the function implementations. To use
2726	it, do the same for F<ev.h> in all files wishing to use this API (best	3173	it, do the same for F<ev.h> in all files wishing to use this API (best
2727	done by writing a wrapper around F<ev.h> that you can include instead and	3174	done by writing a wrapper around F<ev.h> that you can include instead and
2728	where you can put other configuration options):	3175	where you can put other configuration options):
2729		3176
2730	#define EV_STANDALONE 1	3177	#define EV_STANDALONE 1
2731	#include "ev.h"	3178	#include "ev.h"
2732		3179
2733	Both header files and implementation files can be compiled with a C++	3180	Both header files and implementation files can be compiled with a C++
2734	compiler (at least, thats a stated goal, and breakage will be treated	3181	compiler (at least, that's a stated goal, and breakage will be treated
2735	as a bug).	3182	as a bug).
2736		3183
2737	You need the following files in your source tree, or in a directory	3184	You need the following files in your source tree, or in a directory
2738	in your include path (e.g. in libev/ when using -Ilibev):	3185	in your include path (e.g. in libev/ when using -Ilibev):
2739		3186
2740	ev.h	3187	ev.h
2741	ev.c	3188	ev.c
2742	ev_vars.h	3189	ev_vars.h
2743	ev_wrap.h	3190	ev_wrap.h
2744		3191
2745	ev_win32.c required on win32 platforms only	3192	ev_win32.c required on win32 platforms only
2746		3193
2747	ev_select.c only when select backend is enabled (which is enabled by default)	3194	ev_select.c only when select backend is enabled (which is enabled by default)
2748	ev_poll.c only when poll backend is enabled (disabled by default)	3195	ev_poll.c only when poll backend is enabled (disabled by default)
2749	ev_epoll.c only when the epoll backend is enabled (disabled by default)	3196	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2750	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	3197	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2751	ev_port.c only when the solaris port backend is enabled (disabled by default)	3198	ev_port.c only when the solaris port backend is enabled (disabled by default)
2752		3199
2753	F<ev.c> includes the backend files directly when enabled, so you only need	3200	F<ev.c> includes the backend files directly when enabled, so you only need
2754	to compile this single file.	3201	to compile this single file.
2755		3202
2756	=head3 LIBEVENT COMPATIBILITY API	3203	=head3 LIBEVENT COMPATIBILITY API
2757		3204
2758	To include the libevent compatibility API, also include:	3205	To include the libevent compatibility API, also include:
2759		3206
2760	#include "event.c"	3207	#include "event.c"
2761		3208
2762	in the file including F<ev.c>, and:	3209	in the file including F<ev.c>, and:
2763		3210
2764	#include "event.h"	3211	#include "event.h"
2765		3212
2766	in the files that want to use the libevent API. This also includes F<ev.h>.	3213	in the files that want to use the libevent API. This also includes F<ev.h>.
2767		3214
2768	You need the following additional files for this:	3215	You need the following additional files for this:
2769		3216
2770	event.h	3217	event.h
2771	event.c	3218	event.c
2772		3219
2773	=head3 AUTOCONF SUPPORT	3220	=head3 AUTOCONF SUPPORT
2774		3221
2775	Instead of using C<EV_STANDALONE=1> and providing your config in	3222	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2776	whatever way you want, you can also C<m4_include([libev.m4])> in your	3223	whatever way you want, you can also C<m4_include([libev.m4])> in your
2777	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	3224	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2778	include F<config.h> and configure itself accordingly.	3225	include F<config.h> and configure itself accordingly.
2779		3226
2780	For this of course you need the m4 file:	3227	For this of course you need the m4 file:
2781		3228
2782	libev.m4	3229	libev.m4
2783		3230
2784	=head2 PREPROCESSOR SYMBOLS/MACROS	3231	=head2 PREPROCESSOR SYMBOLS/MACROS
2785		3232
2786	Libev can be configured via a variety of preprocessor symbols you have to	3233	Libev can be configured via a variety of preprocessor symbols you have to
2787	define before including any of its files. The default in the absense of	3234	define before including any of its files. The default in the absence of
2788	autoconf is noted for every option.	3235	autoconf is documented for every option.
2789		3236
2790	=over 4	3237	=over 4
2791		3238
2792	=item EV_STANDALONE	3239	=item EV_STANDALONE
2793		3240
…		…
2795	keeps libev from including F<config.h>, and it also defines dummy	3242	keeps libev from including F<config.h>, and it also defines dummy
2796	implementations for some libevent functions (such as logging, which is not	3243	implementations for some libevent functions (such as logging, which is not
2797	supported). It will also not define any of the structs usually found in	3244	supported). It will also not define any of the structs usually found in
2798	F<event.h> that are not directly supported by the libev core alone.	3245	F<event.h> that are not directly supported by the libev core alone.
2799		3246
		3247	In stanbdalone mode, libev will still try to automatically deduce the
		3248	configuration, but has to be more conservative.
		3249
2800	=item EV_USE_MONOTONIC	3250	=item EV_USE_MONOTONIC
2801		3251
2802	If defined to be C<1>, libev will try to detect the availability of the	3252	If defined to be C<1>, libev will try to detect the availability of the
2803	monotonic clock option at both compiletime and runtime. Otherwise no use	3253	monotonic clock option at both compile time and runtime. Otherwise no
2804	of the monotonic clock option will be attempted. If you enable this, you	3254	use of the monotonic clock option will be attempted. If you enable this,
2805	usually have to link against librt or something similar. Enabling it when	3255	you usually have to link against librt or something similar. Enabling it
2806	the functionality isn't available is safe, though, although you have	3256	when the functionality isn't available is safe, though, although you have
2807	to make sure you link against any libraries where the C<clock_gettime>	3257	to make sure you link against any libraries where the C<clock_gettime>
2808	function is hiding in (often F<-lrt>).	3258	function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>.
2809		3259
2810	=item EV_USE_REALTIME	3260	=item EV_USE_REALTIME
2811		3261
2812	If defined to be C<1>, libev will try to detect the availability of the	3262	If defined to be C<1>, libev will try to detect the availability of the
2813	realtime clock option at compiletime (and assume its availability at	3263	real-time clock option at compile time (and assume its availability
2814	runtime if successful). Otherwise no use of the realtime clock option will	3264	at runtime if successful). Otherwise no use of the real-time clock
2815	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	3265	option will be attempted. This effectively replaces C<gettimeofday>
2816	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	3266	by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect
2817	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	3267	correctness. See the note about libraries in the description of
		3268	C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of
		3269	C<EV_USE_CLOCK_SYSCALL>.
		3270
		3271	=item EV_USE_CLOCK_SYSCALL
		3272
		3273	If defined to be C<1>, libev will try to use a direct syscall instead
		3274	of calling the system-provided C<clock_gettime> function. This option
		3275	exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt>
		3276	unconditionally pulls in C<libpthread>, slowing down single-threaded
		3277	programs needlessly. Using a direct syscall is slightly slower (in
		3278	theory), because no optimised vdso implementation can be used, but avoids
		3279	the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or
		3280	higher, as it simplifies linking (no need for C<-lrt>).
2818		3281
2819	=item EV_USE_NANOSLEEP	3282	=item EV_USE_NANOSLEEP
2820		3283
2821	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	3284	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
2822	and will use it for delays. Otherwise it will use C<select ()>.	3285	and will use it for delays. Otherwise it will use C<select ()>.
…		…
2830	2.7 or newer, otherwise disabled.	3293	2.7 or newer, otherwise disabled.
2831		3294
2832	=item EV_USE_SELECT	3295	=item EV_USE_SELECT
2833		3296
2834	If undefined or defined to be C<1>, libev will compile in support for the	3297	If undefined or defined to be C<1>, libev will compile in support for the
2835	C<select>(2) backend. No attempt at autodetection will be done: if no	3298	C<select>(2) backend. No attempt at auto-detection will be done: if no
2836	other method takes over, select will be it. Otherwise the select backend	3299	other method takes over, select will be it. Otherwise the select backend
2837	will not be compiled in.	3300	will not be compiled in.
2838		3301
2839	=item EV_SELECT_USE_FD_SET	3302	=item EV_SELECT_USE_FD_SET
2840		3303
2841	If defined to C<1>, then the select backend will use the system C<fd_set>	3304	If defined to C<1>, then the select backend will use the system C<fd_set>
2842	structure. This is useful if libev doesn't compile due to a missing	3305	structure. This is useful if libev doesn't compile due to a missing
2843	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	3306	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout
2844	exotic systems. This usually limits the range of file descriptors to some	3307	on exotic systems. This usually limits the range of file descriptors to
2845	low limit such as 1024 or might have other limitations (winsocket only	3308	some low limit such as 1024 or might have other limitations (winsocket
2846	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	3309	only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation,
2847	influence the size of the C<fd_set> used.	3310	configures the maximum size of the C<fd_set>.
2848		3311
2849	=item EV_SELECT_IS_WINSOCKET	3312	=item EV_SELECT_IS_WINSOCKET
2850		3313
2851	When defined to C<1>, the select backend will assume that	3314	When defined to C<1>, the select backend will assume that
2852	select/socket/connect etc. don't understand file descriptors but	3315	select/socket/connect etc. don't understand file descriptors but
…		…
2897	otherwise another method will be used as fallback. This is the preferred	3360	otherwise another method will be used as fallback. This is the preferred
2898	backend for Solaris 10 systems.	3361	backend for Solaris 10 systems.
2899		3362
2900	=item EV_USE_DEVPOLL	3363	=item EV_USE_DEVPOLL
2901		3364
2902	reserved for future expansion, works like the USE symbols above.	3365	Reserved for future expansion, works like the USE symbols above.
2903		3366
2904	=item EV_USE_INOTIFY	3367	=item EV_USE_INOTIFY
2905		3368
2906	If defined to be C<1>, libev will compile in support for the Linux inotify	3369	If defined to be C<1>, libev will compile in support for the Linux inotify
2907	interface to speed up C<ev_stat> watchers. Its actual availability will	3370	interface to speed up C<ev_stat> watchers. Its actual availability will
…		…
2914	access is atomic with respect to other threads or signal contexts. No such	3377	access is atomic with respect to other threads or signal contexts. No such
2915	type is easily found in the C language, so you can provide your own type	3378	type is easily found in the C language, so you can provide your own type
2916	that you know is safe for your purposes. It is used both for signal handler "locking"	3379	that you know is safe for your purposes. It is used both for signal handler "locking"
2917	as well as for signal and thread safety in C<ev_async> watchers.	3380	as well as for signal and thread safety in C<ev_async> watchers.
2918		3381
2919	In the absense of this define, libev will use C<sig_atomic_t volatile>	3382	In the absence of this define, libev will use C<sig_atomic_t volatile>
2920	(from F<signal.h>), which is usually good enough on most platforms.	3383	(from F<signal.h>), which is usually good enough on most platforms.
2921		3384
2922	=item EV_H	3385	=item EV_H
2923		3386
2924	The name of the F<ev.h> header file used to include it. The default if	3387	The name of the F<ev.h> header file used to include it. The default if
…		…
2963	When doing priority-based operations, libev usually has to linearly search	3426	When doing priority-based operations, libev usually has to linearly search
2964	all the priorities, so having many of them (hundreds) uses a lot of space	3427	all the priorities, so having many of them (hundreds) uses a lot of space
2965	and time, so using the defaults of five priorities (-2 .. +2) is usually	3428	and time, so using the defaults of five priorities (-2 .. +2) is usually
2966	fine.	3429	fine.
2967		3430
2968	If your embedding app does not need any priorities, defining these both to	3431	If your embedding application does not need any priorities, defining these
2969	C<0> will save some memory and cpu.	3432	both to C<0> will save some memory and CPU.
2970		3433
2971	=item EV_PERIODIC_ENABLE	3434	=item EV_PERIODIC_ENABLE
2972		3435
2973	If undefined or defined to be C<1>, then periodic timers are supported. If	3436	If undefined or defined to be C<1>, then periodic timers are supported. If
2974	defined to be C<0>, then they are not. Disabling them saves a few kB of	3437	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2981	code.	3444	code.
2982		3445
2983	=item EV_EMBED_ENABLE	3446	=item EV_EMBED_ENABLE
2984		3447
2985	If undefined or defined to be C<1>, then embed watchers are supported. If	3448	If undefined or defined to be C<1>, then embed watchers are supported. If
2986	defined to be C<0>, then they are not.	3449	defined to be C<0>, then they are not. Embed watchers rely on most other
		3450	watcher types, which therefore must not be disabled.
2987		3451
2988	=item EV_STAT_ENABLE	3452	=item EV_STAT_ENABLE
2989		3453
2990	If undefined or defined to be C<1>, then stat watchers are supported. If	3454	If undefined or defined to be C<1>, then stat watchers are supported. If
2991	defined to be C<0>, then they are not.	3455	defined to be C<0>, then they are not.
…		…
3002		3466
3003	=item EV_MINIMAL	3467	=item EV_MINIMAL
3004		3468
3005	If you need to shave off some kilobytes of code at the expense of some	3469	If you need to shave off some kilobytes of code at the expense of some
3006	speed, define this symbol to C<1>. Currently this is used to override some	3470	speed, define this symbol to C<1>. Currently this is used to override some
3007	inlining decisions, saves roughly 30% codesize of amd64. It also selects a	3471	inlining decisions, saves roughly 30% code size on amd64. It also selects a
3008	much smaller 2-heap for timer management over the default 4-heap.	3472	much smaller 2-heap for timer management over the default 4-heap.
3009		3473
3010	=item EV_PID_HASHSIZE	3474	=item EV_PID_HASHSIZE
3011		3475
3012	C<ev_child> watchers use a small hash table to distribute workload by	3476	C<ev_child> watchers use a small hash table to distribute workload by
…		…
3023	two).	3487	two).
3024		3488
3025	=item EV_USE_4HEAP	3489	=item EV_USE_4HEAP
3026		3490
3027	Heaps are not very cache-efficient. To improve the cache-efficiency of the	3491	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3028	timer and periodics heap, libev uses a 4-heap when this symbol is defined	3492	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3029	to C<1>. The 4-heap uses more complicated (longer) code but has	3493	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3030	noticably faster performance with many (thousands) of watchers.	3494	faster performance with many (thousands) of watchers.
3031		3495
3032	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	3496	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
3033	(disabled).	3497	(disabled).
3034		3498
3035	=item EV_HEAP_CACHE_AT	3499	=item EV_HEAP_CACHE_AT
3036		3500
3037	Heaps are not very cache-efficient. To improve the cache-efficiency of the	3501	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3038	timer and periodics heap, libev can cache the timestamp (I<at>) within	3502	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3039	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	3503	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3040	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	3504	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3041	but avoids random read accesses on heap changes. This improves performance	3505	but avoids random read accesses on heap changes. This improves performance
3042	noticably with with many (hundreds) of watchers.	3506	noticeably with many (hundreds) of watchers.
3043		3507
3044	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	3508	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
3045	(disabled).	3509	(disabled).
3046		3510
3047	=item EV_VERIFY	3511	=item EV_VERIFY
…		…
3053	called once per loop, which can slow down libev. If set to C<3>, then the	3517	called once per loop, which can slow down libev. If set to C<3>, then the
3054	verification code will be called very frequently, which will slow down	3518	verification code will be called very frequently, which will slow down
3055	libev considerably.	3519	libev considerably.
3056		3520
3057	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	3521	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
3058	C<0.>	3522	C<0>.
3059		3523
3060	=item EV_COMMON	3524	=item EV_COMMON
3061		3525
3062	By default, all watchers have a C<void *data> member. By redefining	3526	By default, all watchers have a C<void *data> member. By redefining
3063	this macro to a something else you can include more and other types of	3527	this macro to a something else you can include more and other types of
3064	members. You have to define it each time you include one of the files,	3528	members. You have to define it each time you include one of the files,
3065	though, and it must be identical each time.	3529	though, and it must be identical each time.
3066		3530
3067	For example, the perl EV module uses something like this:	3531	For example, the perl EV module uses something like this:
3068		3532
3069	#define EV_COMMON \	3533	#define EV_COMMON \
3070	SV *self; /* contains this struct */ \	3534	SV *self; /* contains this struct */ \
3071	SV *cb_sv, *fh /* note no trailing ";" */	3535	SV *cb_sv, *fh /* note no trailing ";" */
3072		3536
3073	=item EV_CB_DECLARE (type)	3537	=item EV_CB_DECLARE (type)
3074		3538
3075	=item EV_CB_INVOKE (watcher, revents)	3539	=item EV_CB_INVOKE (watcher, revents)
3076		3540
…		…
3081	definition and a statement, respectively. See the F<ev.h> header file for	3545	definition and a statement, respectively. See the F<ev.h> header file for
3082	their default definitions. One possible use for overriding these is to	3546	their default definitions. One possible use for overriding these is to
3083	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3547	avoid the C<struct ev_loop *> as first argument in all cases, or to use
3084	method calls instead of plain function calls in C++.	3548	method calls instead of plain function calls in C++.
3085		3549
		3550	=back
		3551
3086	=head2 EXPORTED API SYMBOLS	3552	=head2 EXPORTED API SYMBOLS
3087		3553
3088	If you need to re-export the API (e.g. via a dll) and you need a list of	3554	If you need to re-export the API (e.g. via a DLL) and you need a list of
3089	exported symbols, you can use the provided F<Symbol.*> files which list	3555	exported symbols, you can use the provided F<Symbol.*> files which list
3090	all public symbols, one per line:	3556	all public symbols, one per line:
3091		3557
3092	Symbols.ev for libev proper	3558	Symbols.ev for libev proper
3093	Symbols.event for the libevent emulation	3559	Symbols.event for the libevent emulation
3094		3560
3095	This can also be used to rename all public symbols to avoid clashes with	3561	This can also be used to rename all public symbols to avoid clashes with
3096	multiple versions of libev linked together (which is obviously bad in	3562	multiple versions of libev linked together (which is obviously bad in
3097	itself, but sometimes it is inconvinient to avoid this).	3563	itself, but sometimes it is inconvenient to avoid this).
3098		3564
3099	A sed command like this will create wrapper C<#define>'s that you need to	3565	A sed command like this will create wrapper C<#define>'s that you need to
3100	include before including F<ev.h>:	3566	include before including F<ev.h>:
3101		3567
3102	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3568	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3119	file.	3585	file.
3120		3586
3121	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3587	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3122	that everybody includes and which overrides some configure choices:	3588	that everybody includes and which overrides some configure choices:
3123		3589
3124	#define EV_MINIMAL 1	3590	#define EV_MINIMAL 1
3125	#define EV_USE_POLL 0	3591	#define EV_USE_POLL 0
3126	#define EV_MULTIPLICITY 0	3592	#define EV_MULTIPLICITY 0
3127	#define EV_PERIODIC_ENABLE 0	3593	#define EV_PERIODIC_ENABLE 0
3128	#define EV_STAT_ENABLE 0	3594	#define EV_STAT_ENABLE 0
3129	#define EV_FORK_ENABLE 0	3595	#define EV_FORK_ENABLE 0
3130	#define EV_CONFIG_H <config.h>	3596	#define EV_CONFIG_H <config.h>
3131	#define EV_MINPRI 0	3597	#define EV_MINPRI 0
3132	#define EV_MAXPRI 0	3598	#define EV_MAXPRI 0
3133		3599
3134	#include "ev++.h"	3600	#include "ev++.h"
3135		3601
3136	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3602	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3137		3603
3138	#include "ev_cpp.h"	3604	#include "ev_cpp.h"
3139	#include "ev.c"	3605	#include "ev.c"
3140		3606
		3607	=head1 INTERACTION WITH OTHER PROGRAMS OR LIBRARIES
3141		3608
3142	=head1 THREADS AND COROUTINES	3609	=head2 THREADS AND COROUTINES
3143		3610
3144	=head2 THREADS	3611	=head3 THREADS
3145		3612
3146	Libev itself is completely threadsafe, but it uses no locking. This	3613	All libev functions are reentrant and thread-safe unless explicitly
		3614	documented otherwise, but libev implements no locking itself. This means
3147	means that you can use as many loops as you want in parallel, as long as	3615	that you can use as many loops as you want in parallel, as long as there
3148	only one thread ever calls into one libev function with the same loop	3616	are no concurrent calls into any libev function with the same loop
3149	parameter.	3617	parameter (C<ev_default_*> calls have an implicit default loop parameter,
		3618	of course): libev guarantees that different event loops share no data
		3619	structures that need any locking.
3150		3620
3151	Or put differently: calls with different loop parameters can be done in	3621	Or to put it differently: calls with different loop parameters can be done
3152	parallel from multiple threads, calls with the same loop parameter must be	3622	concurrently from multiple threads, calls with the same loop parameter
3153	done serially (but can be done from different threads, as long as only one	3623	must be done serially (but can be done from different threads, as long as
3154	thread ever is inside a call at any point in time, e.g. by using a mutex	3624	only one thread ever is inside a call at any point in time, e.g. by using
3155	per loop).	3625	a mutex per loop).
3156		3626
3157	If you want to know which design is best for your problem, then I cannot	3627	Specifically to support threads (and signal handlers), libev implements
		3628	so-called C<ev_async> watchers, which allow some limited form of
		3629	concurrency on the same event loop, namely waking it up "from the
		3630	outside".
		3631
		3632	If you want to know which design (one loop, locking, or multiple loops
		3633	without or something else still) is best for your problem, then I cannot
3158	help you but by giving some generic advice:	3634	help you, but here is some generic advice:
3159		3635
3160	=over 4	3636	=over 4
3161		3637
3162	=item * most applications have a main thread: use the default libev loop	3638	=item * most applications have a main thread: use the default libev loop
3163	in that thread, or create a seperate thread running only the default loop.	3639	in that thread, or create a separate thread running only the default loop.
3164		3640
3165	This helps integrating other libraries or software modules that use libev	3641	This helps integrating other libraries or software modules that use libev
3166	themselves and don't care/know about threading.	3642	themselves and don't care/know about threading.
3167		3643
3168	=item * one loop per thread is usually a good model.	3644	=item * one loop per thread is usually a good model.
3169		3645
3170	Doing this is almost never wrong, sometimes a better-performance model	3646	Doing this is almost never wrong, sometimes a better-performance model
3171	exists, but it is always a good start.	3647	exists, but it is always a good start.
3172		3648
3173	=item * other models exist, such as the leader/follower pattern, where one	3649	=item * other models exist, such as the leader/follower pattern, where one
3174	loop is handed through multiple threads in a kind of round-robbin fashion.	3650	loop is handed through multiple threads in a kind of round-robin fashion.
3175		3651
3176	Chosing a model is hard - look around, learn, know that usually you cna do	3652	Choosing a model is hard - look around, learn, know that usually you can do
3177	better than you currently do :-)	3653	better than you currently do :-)
3178		3654
3179	=item * often you need to talk to some other thread which blocks in the	3655	=item * often you need to talk to some other thread which blocks in the
		3656	event loop.
		3657
3180	event loop - C<ev_async> watchers can be used to wake them up from other	3658	C<ev_async> watchers can be used to wake them up from other threads safely
3181	threads safely (or from signal contexts...).	3659	(or from signal contexts...).
		3660
		3661	An example use would be to communicate signals or other events that only
		3662	work in the default loop by registering the signal watcher with the
		3663	default loop and triggering an C<ev_async> watcher from the default loop
		3664	watcher callback into the event loop interested in the signal.
3182		3665
3183	=back	3666	=back
3184		3667
3185	=head2 COROUTINES	3668	=head3 COROUTINES
3186		3669
3187	Libev is much more accomodating to coroutines ("cooperative threads"):	3670	Libev is very accommodating to coroutines ("cooperative threads"):
3188	libev fully supports nesting calls to it's functions from different	3671	libev fully supports nesting calls to its functions from different
3189	coroutines (e.g. you can call C<ev_loop> on the same loop from two	3672	coroutines (e.g. you can call C<ev_loop> on the same loop from two
3190	different coroutines and switch freely between both coroutines running the	3673	different coroutines, and switch freely between both coroutines running the
3191	loop, as long as you don't confuse yourself). The only exception is that	3674	loop, as long as you don't confuse yourself). The only exception is that
3192	you must not do this from C<ev_periodic> reschedule callbacks.	3675	you must not do this from C<ev_periodic> reschedule callbacks.
3193		3676
3194	Care has been invested into making sure that libev does not keep local	3677	Care has been taken to ensure that libev does not keep local state inside
3195	state inside C<ev_loop>, and other calls do not usually allow coroutine	3678	C<ev_loop>, and other calls do not usually allow for coroutine switches as
3196	switches.	3679	they do not call any callbacks.
3197		3680
		3681	=head2 COMPILER WARNINGS
3198		3682
3199	=head1 COMPLEXITIES	3683	Depending on your compiler and compiler settings, you might get no or a
		3684	lot of warnings when compiling libev code. Some people are apparently
		3685	scared by this.
3200		3686
3201	In this section the complexities of (many of) the algorithms used inside	3687	However, these are unavoidable for many reasons. For one, each compiler
3202	libev will be explained. For complexity discussions about backends see the	3688	has different warnings, and each user has different tastes regarding
3203	documentation for C<ev_default_init>.	3689	warning options. "Warn-free" code therefore cannot be a goal except when
		3690	targeting a specific compiler and compiler-version.
3204		3691
3205	All of the following are about amortised time: If an array needs to be	3692	Another reason is that some compiler warnings require elaborate
3206	extended, libev needs to realloc and move the whole array, but this	3693	workarounds, or other changes to the code that make it less clear and less
3207	happens asymptotically never with higher number of elements, so O(1) might	3694	maintainable.
3208	mean it might do a lengthy realloc operation in rare cases, but on average
3209	it is much faster and asymptotically approaches constant time.
3210		3695
3211	=over 4	3696	And of course, some compiler warnings are just plain stupid, or simply
		3697	wrong (because they don't actually warn about the condition their message
		3698	seems to warn about). For example, certain older gcc versions had some
		3699	warnings that resulted an extreme number of false positives. These have
		3700	been fixed, but some people still insist on making code warn-free with
		3701	such buggy versions.
3212		3702
3213	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	3703	While libev is written to generate as few warnings as possible,
		3704	"warn-free" code is not a goal, and it is recommended not to build libev
		3705	with any compiler warnings enabled unless you are prepared to cope with
		3706	them (e.g. by ignoring them). Remember that warnings are just that:
		3707	warnings, not errors, or proof of bugs.
3214		3708
3215	This means that, when you have a watcher that triggers in one hour and
3216	there are 100 watchers that would trigger before that then inserting will
3217	have to skip roughly seven (C<ld 100>) of these watchers.
3218		3709
3219	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)	3710	=head2 VALGRIND
3220		3711
3221	That means that changing a timer costs less than removing/adding them	3712	Valgrind has a special section here because it is a popular tool that is
3222	as only the relative motion in the event queue has to be paid for.	3713	highly useful. Unfortunately, valgrind reports are very hard to interpret.
3223		3714
3224	=item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)	3715	If you think you found a bug (memory leak, uninitialised data access etc.)
		3716	in libev, then check twice: If valgrind reports something like:
3225		3717
3226	These just add the watcher into an array or at the head of a list.	3718	==2274== definitely lost: 0 bytes in 0 blocks.
		3719	==2274== possibly lost: 0 bytes in 0 blocks.
		3720	==2274== still reachable: 256 bytes in 1 blocks.
3227		3721
3228	=item Stopping check/prepare/idle/fork/async watchers: O(1)	3722	Then there is no memory leak, just as memory accounted to global variables
		3723	is not a memleak - the memory is still being referenced, and didn't leak.
3229		3724
3230	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	3725	Similarly, under some circumstances, valgrind might report kernel bugs
		3726	as if it were a bug in libev (e.g. in realloc or in the poll backend,
		3727	although an acceptable workaround has been found here), or it might be
		3728	confused.
3231		3729
3232	These watchers are stored in lists then need to be walked to find the	3730	Keep in mind that valgrind is a very good tool, but only a tool. Don't
3233	correct watcher to remove. The lists are usually short (you don't usually	3731	make it into some kind of religion.
3234	have many watchers waiting for the same fd or signal).
3235		3732
3236	=item Finding the next timer in each loop iteration: O(1)	3733	If you are unsure about something, feel free to contact the mailing list
		3734	with the full valgrind report and an explanation on why you think this
		3735	is a bug in libev (best check the archives, too :). However, don't be
		3736	annoyed when you get a brisk "this is no bug" answer and take the chance
		3737	of learning how to interpret valgrind properly.
3237		3738
3238	By virtue of using a binary or 4-heap, the next timer is always found at a	3739	If you need, for some reason, empty reports from valgrind for your project
3239	fixed position in the storage array.	3740	I suggest using suppression lists.
3240		3741
3241	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3242		3742
3243	A change means an I/O watcher gets started or stopped, which requires	3743	=head1 PORTABILITY NOTES
3244	libev to recalculate its status (and possibly tell the kernel, depending
3245	on backend and wether C<ev_io_set> was used).
3246		3744
3247	=item Activating one watcher (putting it into the pending state): O(1)	3745	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3248
3249	=item Priority handling: O(number_of_priorities)
3250
3251	Priorities are implemented by allocating some space for each
3252	priority. When doing priority-based operations, libev usually has to
3253	linearly search all the priorities, but starting/stopping and activating
3254	watchers becomes O(1) w.r.t. priority handling.
3255
3256	=item Sending an ev_async: O(1)
3257
3258	=item Processing ev_async_send: O(number_of_async_watchers)
3259
3260	=item Processing signals: O(max_signal_number)
3261
3262	Sending involves a syscall I<iff> there were no other C<ev_async_send>
3263	calls in the current loop iteration. Checking for async and signal events
3264	involves iterating over all running async watchers or all signal numbers.
3265
3266	=back
3267
3268
3269	=head1 Win32 platform limitations and workarounds
3270		3746
3271	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3747	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3272	requires, and its I/O model is fundamentally incompatible with the POSIX	3748	requires, and its I/O model is fundamentally incompatible with the POSIX
3273	model. Libev still offers limited functionality on this platform in	3749	model. Libev still offers limited functionality on this platform in
3274	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3750	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
…		…
3281	way (note also that glib is the slowest event library known to man).	3757	way (note also that glib is the slowest event library known to man).
3282		3758
3283	There is no supported compilation method available on windows except	3759	There is no supported compilation method available on windows except
3284	embedding it into other applications.	3760	embedding it into other applications.
3285		3761
		3762	Not a libev limitation but worth mentioning: windows apparently doesn't
		3763	accept large writes: instead of resulting in a partial write, windows will
		3764	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3765	so make sure you only write small amounts into your sockets (less than a
		3766	megabyte seems safe, but this apparently depends on the amount of memory
		3767	available).
		3768
3286	Due to the many, low, and arbitrary limits on the win32 platform and	3769	Due to the many, low, and arbitrary limits on the win32 platform and
3287	the abysmal performance of winsockets, using a large number of sockets	3770	the abysmal performance of winsockets, using a large number of sockets
3288	is not recommended (and not reasonable). If your program needs to use	3771	is not recommended (and not reasonable). If your program needs to use
3289	more than a hundred or so sockets, then likely it needs to use a totally	3772	more than a hundred or so sockets, then likely it needs to use a totally
3290	different implementation for windows, as libev offers the POSIX readiness	3773	different implementation for windows, as libev offers the POSIX readiness
3291	notification model, which cannot be implemented efficiently on windows	3774	notification model, which cannot be implemented efficiently on windows
3292	(microsoft monopoly games).	3775	(Microsoft monopoly games).
		3776
		3777	A typical way to use libev under windows is to embed it (see the embedding
		3778	section for details) and use the following F<evwrap.h> header file instead
		3779	of F<ev.h>:
		3780
		3781	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3782	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3783
		3784	#include "ev.h"
		3785
		3786	And compile the following F<evwrap.c> file into your project (make sure
		3787	you do I<not> compile the F<ev.c> or any other embedded source files!):
		3788
		3789	#include "evwrap.h"
		3790	#include "ev.c"
3293		3791
3294	=over 4	3792	=over 4
3295		3793
3296	=item The winsocket select function	3794	=item The winsocket select function
3297		3795
3298	The winsocket C<select> function doesn't follow POSIX in that it requires	3796	The winsocket C<select> function doesn't follow POSIX in that it
3299	socket I<handles> and not socket I<file descriptors>. This makes select	3797	requires socket I<handles> and not socket I<file descriptors> (it is
3300	very inefficient, and also requires a mapping from file descriptors	3798	also extremely buggy). This makes select very inefficient, and also
3301	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3799	requires a mapping from file descriptors to socket handles (the Microsoft
3302	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3800	C runtime provides the function C<_open_osfhandle> for this). See the
3303	symbols for more info.	3801	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3802	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3304		3803
3305	The configuration for a "naked" win32 using the microsoft runtime	3804	The configuration for a "naked" win32 using the Microsoft runtime
3306	libraries and raw winsocket select is:	3805	libraries and raw winsocket select is:
3307		3806
3308	#define EV_USE_SELECT 1	3807	#define EV_USE_SELECT 1
3309	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3808	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3310		3809
3311	Note that winsockets handling of fd sets is O(n), so you can easily get a	3810	Note that winsockets handling of fd sets is O(n), so you can easily get a
3312	complexity in the O(n²) range when using win32.	3811	complexity in the O(n²) range when using win32.
3313		3812
3314	=item Limited number of file descriptors	3813	=item Limited number of file descriptors
3315		3814
3316	Windows has numerous arbitrary (and low) limits on things.	3815	Windows has numerous arbitrary (and low) limits on things.
3317		3816
3318	Early versions of winsocket's select only supported waiting for a maximum	3817	Early versions of winsocket's select only supported waiting for a maximum
3319	of C<64> handles (probably owning to the fact that all windows kernels	3818	of C<64> handles (probably owning to the fact that all windows kernels
3320	can only wait for C<64> things at the same time internally; microsoft	3819	can only wait for C<64> things at the same time internally; Microsoft
3321	recommends spawning a chain of threads and wait for 63 handles and the	3820	recommends spawning a chain of threads and wait for 63 handles and the
3322	previous thread in each. Great).	3821	previous thread in each. Great).
3323		3822
3324	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3823	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3325	to some high number (e.g. C<2048>) before compiling the winsocket select	3824	to some high number (e.g. C<2048>) before compiling the winsocket select
3326	call (which might be in libev or elsewhere, for example, perl does its own	3825	call (which might be in libev or elsewhere, for example, perl does its own
3327	select emulation on windows).	3826	select emulation on windows).
3328		3827
3329	Another limit is the number of file descriptors in the microsoft runtime	3828	Another limit is the number of file descriptors in the Microsoft runtime
3330	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3829	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3331	or something like this inside microsoft). You can increase this by calling	3830	or something like this inside Microsoft). You can increase this by calling
3332	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3831	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3333	arbitrary limit), but is broken in many versions of the microsoft runtime	3832	arbitrary limit), but is broken in many versions of the Microsoft runtime
3334	libraries.	3833	libraries.
3335		3834
3336	This might get you to about C<512> or C<2048> sockets (depending on	3835	This might get you to about C<512> or C<2048> sockets (depending on
3337	windows version and/or the phase of the moon). To get more, you need to	3836	windows version and/or the phase of the moon). To get more, you need to
3338	wrap all I/O functions and provide your own fd management, but the cost of	3837	wrap all I/O functions and provide your own fd management, but the cost of
3339	calling select (O(n²)) will likely make this unworkable.	3838	calling select (O(n²)) will likely make this unworkable.
3340		3839
3341	=back	3840	=back
3342		3841
3343
3344	=head1 PORTABILITY REQUIREMENTS	3842	=head2 PORTABILITY REQUIREMENTS
3345		3843
3346	In addition to a working ISO-C implementation, libev relies on a few	3844	In addition to a working ISO-C implementation and of course the
3347	additional extensions:	3845	backend-specific APIs, libev relies on a few additional extensions:
3348		3846
3349	=over 4	3847	=over 4
3350		3848
		3849	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3850	calling conventions regardless of C<ev_watcher_type *>.
		3851
		3852	Libev assumes not only that all watcher pointers have the same internal
		3853	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3854	assumes that the same (machine) code can be used to call any watcher
		3855	callback: The watcher callbacks have different type signatures, but libev
		3856	calls them using an C<ev_watcher *> internally.
		3857
3351	=item C<sig_atomic_t volatile> must be thread-atomic as well	3858	=item C<sig_atomic_t volatile> must be thread-atomic as well
3352		3859
3353	The type C<sig_atomic_t volatile> (or whatever is defined as	3860	The type C<sig_atomic_t volatile> (or whatever is defined as
3354	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different	3861	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
3355	threads. This is not part of the specification for C<sig_atomic_t>, but is	3862	threads. This is not part of the specification for C<sig_atomic_t>, but is
3356	believed to be sufficiently portable.	3863	believed to be sufficiently portable.
3357		3864
3358	=item C<sigprocmask> must work in a threaded environment	3865	=item C<sigprocmask> must work in a threaded environment
3359		3866
…		…
3368	except the initial one, and run the default loop in the initial thread as	3875	except the initial one, and run the default loop in the initial thread as
3369	well.	3876	well.
3370		3877
3371	=item C<long> must be large enough for common memory allocation sizes	3878	=item C<long> must be large enough for common memory allocation sizes
3372		3879
3373	To improve portability and simplify using libev, libev uses C<long>	3880	To improve portability and simplify its API, libev uses C<long> internally
3374	internally instead of C<size_t> when allocating its data structures. On	3881	instead of C<size_t> when allocating its data structures. On non-POSIX
3375	non-POSIX systems (Microsoft...) this might be unexpectedly low, but	3882	systems (Microsoft...) this might be unexpectedly low, but is still at
3376	is still at least 31 bits everywhere, which is enough for hundreds of	3883	least 31 bits everywhere, which is enough for hundreds of millions of
3377	millions of watchers.	3884	watchers.
3378		3885
3379	=item C<double> must hold a time value in seconds with enough accuracy	3886	=item C<double> must hold a time value in seconds with enough accuracy
3380		3887
3381	The type C<double> is used to represent timestamps. It is required to	3888	The type C<double> is used to represent timestamps. It is required to
3382	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	3889	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
…		…
3386	=back	3893	=back
3387		3894
3388	If you know of other additional requirements drop me a note.	3895	If you know of other additional requirements drop me a note.
3389		3896
3390		3897
3391	=head1 VALGRIND	3898	=head1 ALGORITHMIC COMPLEXITIES
3392		3899
3393	Valgrind has a special section here because it is a popular tool that is	3900	In this section the complexities of (many of) the algorithms used inside
3394	highly useful, but valgrind reports are very hard to interpret.	3901	libev will be documented. For complexity discussions about backends see
		3902	the documentation for C<ev_default_init>.
3395		3903
3396	If you think you found a bug (memory leak, uninitialised data access etc.)	3904	All of the following are about amortised time: If an array needs to be
3397	in libev, then check twice: If valgrind reports something like:	3905	extended, libev needs to realloc and move the whole array, but this
		3906	happens asymptotically rarer with higher number of elements, so O(1) might
		3907	mean that libev does a lengthy realloc operation in rare cases, but on
		3908	average it is much faster and asymptotically approaches constant time.
3398		3909
3399	==2274== definitely lost: 0 bytes in 0 blocks.	3910	=over 4
3400	==2274== possibly lost: 0 bytes in 0 blocks.
3401	==2274== still reachable: 256 bytes in 1 blocks.
3402		3911
3403	then there is no memory leak. Similarly, under some circumstances,	3912	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
3404	valgrind might report kernel bugs as if it were a bug in libev, or it
3405	might be confused (it is a very good tool, but only a tool).
3406		3913
3407	If you are unsure about something, feel free to contact the mailing list	3914	This means that, when you have a watcher that triggers in one hour and
3408	with the full valgrind report and an explanation on why you think this is	3915	there are 100 watchers that would trigger before that, then inserting will
3409	a bug in libev. However, don't be annoyed when you get a brisk "this is	3916	have to skip roughly seven (C<ld 100>) of these watchers.
3410	no bug" answer and take the chance of learning how to interpret valgrind
3411	properly.
3412		3917
3413	If you need, for some reason, empty reports from valgrind for your project	3918	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
3414	I suggest using suppression lists.	3919
		3920	That means that changing a timer costs less than removing/adding them,
		3921	as only the relative motion in the event queue has to be paid for.
		3922
		3923	=item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)
		3924
		3925	These just add the watcher into an array or at the head of a list.
		3926
		3927	=item Stopping check/prepare/idle/fork/async watchers: O(1)
		3928
		3929	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		3930
		3931	These watchers are stored in lists, so they need to be walked to find the
		3932	correct watcher to remove. The lists are usually short (you don't usually
		3933	have many watchers waiting for the same fd or signal: one is typical, two
		3934	is rare).
		3935
		3936	=item Finding the next timer in each loop iteration: O(1)
		3937
		3938	By virtue of using a binary or 4-heap, the next timer is always found at a
		3939	fixed position in the storage array.
		3940
		3941	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		3942
		3943	A change means an I/O watcher gets started or stopped, which requires
		3944	libev to recalculate its status (and possibly tell the kernel, depending
		3945	on backend and whether C<ev_io_set> was used).
		3946
		3947	=item Activating one watcher (putting it into the pending state): O(1)
		3948
		3949	=item Priority handling: O(number_of_priorities)
		3950
		3951	Priorities are implemented by allocating some space for each
		3952	priority. When doing priority-based operations, libev usually has to
		3953	linearly search all the priorities, but starting/stopping and activating
		3954	watchers becomes O(1) with respect to priority handling.
		3955
		3956	=item Sending an ev_async: O(1)
		3957
		3958	=item Processing ev_async_send: O(number_of_async_watchers)
		3959
		3960	=item Processing signals: O(max_signal_number)
		3961
		3962	Sending involves a system call I<iff> there were no other C<ev_async_send>
		3963	calls in the current loop iteration. Checking for async and signal events
		3964	involves iterating over all running async watchers or all signal numbers.
		3965
		3966	=back
3415		3967
3416		3968
3417	=head1 AUTHOR	3969	=head1 AUTHOR
3418		3970
3419	Marc Lehmann <libev@schmorp.de>.	3971	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.
3420		3972

Diff Legend

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