ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.262 by root, Sat Jul 25 10:14:34 2009 UTC vs.
Revision 1.351 by root, Mon Jan 10 14:24:26 2011 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	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);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
118	Libev is very configurable. In this manual the default (and most common)	126	Libev is very configurable. In this manual the default (and most common)
119	configuration will be described, which supports multiple event loops. For	127	configuration will be described, which supports multiple event loops. For
120	more info about various configuration options please have a look at	128	more info about various configuration options please have a look at
121	B<EMBED> section in this manual. If libev was configured without support	129	B<EMBED> section in this manual. If libev was configured without support
122	for multiple event loops, then all functions taking an initial argument of	130	for multiple event loops, then all functions taking an initial argument of
123	name C<loop> (which is always of type C<ev_loop *>) will not have	131	name C<loop> (which is always of type C<struct ev_loop *>) will not have
124	this argument.	132	this argument.
125		133
126	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
127		135
128	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (somewhere	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	near the beginning of 1970, details are complicated, don't ask). This	138	somewhere near the beginning of 1970, details are complicated, don't
131	type is called C<ev_tstamp>, which is what you should use too. It usually	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	aliases to the C<double> type in C. When you need to do any calculations	140	too. It usually aliases to the C<double> type in C. When you need to do
133	on it, you should treat it as some floating point value. Unlike the name	141	any calculations on it, you should treat it as some floating point value.
		142
134	component C<stamp> might indicate, it is also used for time differences	143	Unlike the name component C<stamp> might indicate, it is also used for
135	throughout libev.	144	time differences (e.g. delays) throughout libev.
136		145
137	=head1 ERROR HANDLING	146	=head1 ERROR HANDLING
138		147
139	Libev knows three classes of errors: operating system errors, usage errors	148	Libev knows three classes of errors: operating system errors, usage errors
140	and internal errors (bugs).	149	and internal errors (bugs).
…		…
164		173
165	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
166		175
167	Returns the current time as libev would use it. Please note that the	176	Returns the current time as libev would use it. Please note that the
168	C<ev_now> function is usually faster and also often returns the timestamp	177	C<ev_now> function is usually faster and also often returns the timestamp
169	you actually want to know.	178	you actually want to know. Also interesting is the combination of
		179	C<ev_update_now> and C<ev_now>.
170		180
171	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
172		182
173	Sleep for the given interval: The current thread will be blocked until	183	Sleep for the given interval: The current thread will be blocked until
174	either it is interrupted or the given time interval has passed. Basically	184	either it is interrupted or the given time interval has passed. Basically
…		…
191	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
192	compatible to older versions, so a larger minor version alone is usually	202	compatible to older versions, so a larger minor version alone is usually
193	not a problem.	203	not a problem.
194		204
195	Example: Make sure we haven't accidentally been linked against the wrong	205	Example: Make sure we haven't accidentally been linked against the wrong
196	version.	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
197		208
198	assert (("libev version mismatch",	209	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
201		212
…		…
212	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
213	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
214		225
215	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
216		227
217	Return the set of all backends compiled into this binary of libev and also	228	Return the set of all backends compiled into this binary of libev and
218	recommended for this platform. This set is often smaller than the one	229	also recommended for this platform, meaning it will work for most file
		230	descriptor types. This set is often smaller than the one returned by
219	returned by C<ev_supported_backends>, as for example kqueue is broken on	231	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
220	most BSDs and will not be auto-detected unless you explicitly request it	232	and will not be auto-detected unless you explicitly request it (assuming
221	(assuming you know what you are doing). This is the set of backends that	233	you know what you are doing). This is the set of backends that libev will
222	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
223		235
224	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
225		237
226	Returns the set of backends that are embeddable in other event loops. This	238	Returns the set of backends that are embeddable in other event loops. This
227	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
228	might be supported on the current system, you would need to look at	240	current system. To find which embeddable backends might be supported on
229	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
230	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
231		243
232	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
233		245
234	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
235		247
236	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
237	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	249	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
238	used to allocate and free memory (no surprises here). If it returns zero	250	used to allocate and free memory (no surprises here). If it returns zero
239	when memory needs to be allocated (C<size != 0>), the library might abort	251	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
265	}	277	}
266		278
267	...	279	...
268	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
269		281
270	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (*cb)(const char *msg))
271		283
272	Set the callback function to call on a retryable system call error (such	284	Set the callback function to call on a retryable system call error (such
273	as failed select, poll, epoll_wait). The message is a printable string	285	as failed select, poll, epoll_wait). The message is a printable string
274	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
275	callback is set, then libev will expect it to remedy the situation, no	287	callback is set, then libev will expect it to remedy the situation, no
…		…
287	}	299	}
288		300
289	...	301	...
290	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
291		303
		304	=item ev_feed_signal (int signum)
		305
		306	This function can be used to "simulate" a signal receive. It is completely
		307	safe to call this function at any time, from any context, including signal
		308	handlers or random threads.
		309
		310	Its main use is to customise signal handling in your process, especially
		311	in the presence of threads. For example, you could block signals
		312	by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when
		313	creating any loops), and in one thread, use C<sigwait> or any other
		314	mechanism to wait for signals, then "deliver" them to libev by calling
		315	C<ev_feed_signal>.
		316
292	=back	317	=back
293		318
294	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	319	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
295		320
296	An event loop is described by a C<struct ev_loop *> (the C<struct>	321	An event loop is described by a C<struct ev_loop *> (the C<struct> is
297	is I<not> optional in this case, as there is also an C<ev_loop>	322	I<not> optional in this case unless libev 3 compatibility is disabled, as
298	I<function>).	323	libev 3 had an C<ev_loop> function colliding with the struct name).
299		324
300	The library knows two types of such loops, the I<default> loop, which	325	The library knows two types of such loops, the I<default> loop, which
301	supports signals and child events, and dynamically created loops which do	326	supports child process events, and dynamically created event loops which
302	not.	327	do not.
303		328
304	=over 4	329	=over 4
305		330
306	=item struct ev_loop *ev_default_loop (unsigned int flags)	331	=item struct ev_loop *ev_default_loop (unsigned int flags)
307		332
308	This will initialise the default event loop if it hasn't been initialised	333	This returns the "default" event loop object, which is what you should
309	yet and return it. If the default loop could not be initialised, returns	334	normally use when you just need "the event loop". Event loop objects and
310	false. If it already was initialised it simply returns it (and ignores the	335	the C<flags> parameter are described in more detail in the entry for
311	flags. If that is troubling you, check C<ev_backend ()> afterwards).	336	C<ev_loop_new>.
		337
		338	If the default loop is already initialised then this function simply
		339	returns it (and ignores the flags. If that is troubling you, check
		340	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		341	flags, which should almost always be C<0>, unless the caller is also the
		342	one calling C<ev_run> or otherwise qualifies as "the main program".
312		343
313	If you don't know what event loop to use, use the one returned from this	344	If you don't know what event loop to use, use the one returned from this
314	function.	345	function (or via the C<EV_DEFAULT> macro).
315		346
316	Note that this function is I<not> thread-safe, so if you want to use it	347	Note that this function is I<not> thread-safe, so if you want to use it
317	from multiple threads, you have to lock (note also that this is unlikely,	348	from multiple threads, you have to employ some kind of mutex (note also
318	as loops cannot be shared easily between threads anyway).	349	that this case is unlikely, as loops cannot be shared easily between
		350	threads anyway).
319		351
320	The default loop is the only loop that can handle C<ev_signal> and	352	The default loop is the only loop that can handle C<ev_child> watchers,
321	C<ev_child> watchers, and to do this, it always registers a handler	353	and to do this, it always registers a handler for C<SIGCHLD>. If this is
322	for C<SIGCHLD>. If this is a problem for your application you can either	354	a problem for your application you can either create a dynamic loop with
323	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	355	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
324	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	356	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
325	C<ev_default_init>.	357
		358	Example: This is the most typical usage.
		359
		360	if (!ev_default_loop (0))
		361	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		362
		363	Example: Restrict libev to the select and poll backends, and do not allow
		364	environment settings to be taken into account:
		365
		366	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		367
		368	=item struct ev_loop *ev_loop_new (unsigned int flags)
		369
		370	This will create and initialise a new event loop object. If the loop
		371	could not be initialised, returns false.
		372
		373	This function is thread-safe, and one common way to use libev with
		374	threads is indeed to create one loop per thread, and using the default
		375	loop in the "main" or "initial" thread.
326		376
327	The flags argument can be used to specify special behaviour or specific	377	The flags argument can be used to specify special behaviour or specific
328	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	378	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
329		379
330	The following flags are supported:	380	The following flags are supported:
…		…
345	useful to try out specific backends to test their performance, or to work	395	useful to try out specific backends to test their performance, or to work
346	around bugs.	396	around bugs.
347		397
348	=item C<EVFLAG_FORKCHECK>	398	=item C<EVFLAG_FORKCHECK>
349		399
350	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	400	Instead of calling C<ev_loop_fork> manually after a fork, you can also
351	a fork, you can also make libev check for a fork in each iteration by	401	make libev check for a fork in each iteration by enabling this flag.
352	enabling this flag.
353		402
354	This works by calling C<getpid ()> on every iteration of the loop,	403	This works by calling C<getpid ()> on every iteration of the loop,
355	and thus this might slow down your event loop if you do a lot of loop	404	and thus this might slow down your event loop if you do a lot of loop
356	iterations and little real work, but is usually not noticeable (on my	405	iterations and little real work, but is usually not noticeable (on my
357	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	406	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
366	environment variable.	415	environment variable.
367		416
368	=item C<EVFLAG_NOINOTIFY>	417	=item C<EVFLAG_NOINOTIFY>
369		418
370	When this flag is specified, then libev will not attempt to use the	419	When this flag is specified, then libev will not attempt to use the
371	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and	420	I<inotify> API for its C<ev_stat> watchers. Apart from debugging and
372	testing, this flag can be useful to conserve inotify file descriptors, as	421	testing, this flag can be useful to conserve inotify file descriptors, as
373	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.	422	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
374		423
375	=item C<EVFLAG_NOSIGNALFD>	424	=item C<EVFLAG_SIGNALFD>
376		425
377	When this flag is specified, then libev will not attempt to use the	426	When this flag is specified, then libev will attempt to use the
378	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is	427	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
379	probably only useful to work around any bugs in libev. Consequently, this	428	delivers signals synchronously, which makes it both faster and might make
380	flag might go away once the signalfd functionality is considered stable,	429	it possible to get the queued signal data. It can also simplify signal
381	so it's useful mostly in environment variables and not in program code.	430	handling with threads, as long as you properly block signals in your
		431	threads that are not interested in handling them.
		432
		433	Signalfd will not be used by default as this changes your signal mask, and
		434	there are a lot of shoddy libraries and programs (glib's threadpool for
		435	example) that can't properly initialise their signal masks.
		436
		437	=item C<EVFLAG_NOSIGMASK>
		438
		439	When this flag is specified, then libev will avoid to modify the signal
		440	mask. Specifically, this means you ahve to make sure signals are unblocked
		441	when you want to receive them.
		442
		443	This behaviour is useful when you want to do your own signal handling, or
		444	want to handle signals only in specific threads and want to avoid libev
		445	unblocking the signals.
		446
		447	This flag's behaviour will become the default in future versions of libev.
382		448
383	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
384		450
385	This is your standard select(2) backend. Not I<completely> standard, as	451	This is your standard select(2) backend. Not I<completely> standard, as
386	libev tries to roll its own fd_set with no limits on the number of fds,	452	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
411	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and	477	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
412	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.	478	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
413		479
414	=item C<EVBACKEND_EPOLL> (value 4, Linux)	480	=item C<EVBACKEND_EPOLL> (value 4, Linux)
415		481
		482	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
		483	kernels).
		484
416	For few fds, this backend is a bit little slower than poll and select,	485	For few fds, this backend is a bit little slower than poll and select,
417	but it scales phenomenally better. While poll and select usually scale	486	but it scales phenomenally better. While poll and select usually scale
418	like O(total_fds) where n is the total number of fds (or the highest fd),	487	like O(total_fds) where n is the total number of fds (or the highest fd),
419	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
420		489
421	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
422	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
423	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
424	descriptor (and unnecessary guessing of parameters), problems with dup and	493	descriptor (and unnecessary guessing of parameters), problems with dup,
		494	returning before the timeout value, resulting in additional iterations
		495	(and only giving 5ms accuracy while select on the same platform gives
425	so on. The biggest issue is fork races, however - if a program forks then	496	0.1ms) and so on. The biggest issue is fork races, however - if a program
426	I<both> parent and child process have to recreate the epoll set, which can	497	forks then I<both> parent and child process have to recreate the epoll
427	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
428	hard to detect.	499	and is of course hard to detect.
429		500
430	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	501	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
431	of course I<doesn't>, and epoll just loves to report events for totally	502	of course I<doesn't>, and epoll just loves to report events for totally
432	I<different> file descriptors (even already closed ones, so one cannot	503	I<different> file descriptors (even already closed ones, so one cannot
433	even remove them from the set) than registered in the set (especially	504	even remove them from the set) than registered in the set (especially
434	on SMP systems). Libev tries to counter these spurious notifications by	505	on SMP systems). Libev tries to counter these spurious notifications by
435	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
436	events to filter out spurious ones, recreating the set when required.	507	events to filter out spurious ones, recreating the set when required. Last
		508	not least, it also refuses to work with some file descriptors which work
		509	perfectly fine with C<select> (files, many character devices...).
		510
		511	Epoll is truly the train wreck analog among event poll mechanisms.
437		512
438	While stopping, setting and starting an I/O watcher in the same iteration	513	While stopping, setting and starting an I/O watcher in the same iteration
439	will result in some caching, there is still a system call per such	514	will result in some caching, there is still a system call per such
440	incident (because the same I<file descriptor> could point to a different	515	incident (because the same I<file descriptor> could point to a different
441	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	516	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
507	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	582	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
508		583
509	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	584	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
510	it's really slow, but it still scales very well (O(active_fds)).	585	it's really slow, but it still scales very well (O(active_fds)).
511		586
512	Please note that Solaris event ports can deliver a lot of spurious
513	notifications, so you need to use non-blocking I/O or other means to avoid
514	blocking when no data (or space) is available.
515
516	While this backend scales well, it requires one system call per active	587	While this backend scales well, it requires one system call per active
517	file descriptor per loop iteration. For small and medium numbers of file	588	file descriptor per loop iteration. For small and medium numbers of file
518	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	589	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
519	might perform better.	590	might perform better.
520		591
521	On the positive side, with the exception of the spurious readiness	592	On the positive side, this backend actually performed fully to
522	notifications, this backend actually performed fully to specification
523	in all tests and is fully embeddable, which is a rare feat among the	593	specification in all tests and is fully embeddable, which is a rare feat
524	OS-specific backends (I vastly prefer correctness over speed hacks).	594	among the OS-specific backends (I vastly prefer correctness over speed
		595	hacks).
		596
		597	On the negative side, the interface is I<bizarre>, with the event polling
		598	function sometimes returning events to the caller even though an error
		599	occured, but with no indication whether it has done so or not (yes, it's
		600	even documented that way) - deadly for edge-triggered interfaces, but
		601	fortunately libev seems to be able to work around it.
525		602
526	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	603	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
527	C<EVBACKEND_POLL>.	604	C<EVBACKEND_POLL>.
528		605
529	=item C<EVBACKEND_ALL>	606	=item C<EVBACKEND_ALL>
530		607
531	Try all backends (even potentially broken ones that wouldn't be tried	608	Try all backends (even potentially broken ones that wouldn't be tried
532	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	609	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
533	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	610	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
534		611
535	It is definitely not recommended to use this flag.	612	It is definitely not recommended to use this flag, use whatever
		613	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		614	at all.
		615
		616	=item C<EVBACKEND_MASK>
		617
		618	Not a backend at all, but a mask to select all backend bits from a
		619	C<flags> value, in case you want to mask out any backends from a flags
		620	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
536		621
537	=back	622	=back
538		623
539	If one or more of the backend flags are or'ed into the flags value,	624	If one or more of the backend flags are or'ed into the flags value,
540	then only these backends will be tried (in the reverse order as listed	625	then only these backends will be tried (in the reverse order as listed
541	here). If none are specified, all backends in C<ev_recommended_backends	626	here). If none are specified, all backends in C<ev_recommended_backends
542	()> will be tried.	627	()> will be tried.
543		628
544	Example: This is the most typical usage.
545
546	if (!ev_default_loop (0))
547	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
548
549	Example: Restrict libev to the select and poll backends, and do not allow
550	environment settings to be taken into account:
551
552	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
553
554	Example: Use whatever libev has to offer, but make sure that kqueue is
555	used if available (warning, breaks stuff, best use only with your own
556	private event loop and only if you know the OS supports your types of
557	fds):
558
559	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
560
561	=item struct ev_loop *ev_loop_new (unsigned int flags)
562
563	Similar to C<ev_default_loop>, but always creates a new event loop that is
564	always distinct from the default loop. Unlike the default loop, it cannot
565	handle signal and child watchers, and attempts to do so will be greeted by
566	undefined behaviour (or a failed assertion if assertions are enabled).
567
568	Note that this function I<is> thread-safe, and the recommended way to use
569	libev with threads is indeed to create one loop per thread, and using the
570	default loop in the "main" or "initial" thread.
571
572	Example: Try to create a event loop that uses epoll and nothing else.	629	Example: Try to create a event loop that uses epoll and nothing else.
573		630
574	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	631	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
575	if (!epoller)	632	if (!epoller)
576	fatal ("no epoll found here, maybe it hides under your chair");	633	fatal ("no epoll found here, maybe it hides under your chair");
577		634
		635	Example: Use whatever libev has to offer, but make sure that kqueue is
		636	used if available.
		637
		638	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		639
578	=item ev_default_destroy ()	640	=item ev_loop_destroy (loop)
579		641
580	Destroys the default loop again (frees all memory and kernel state	642	Destroys an event loop object (frees all memory and kernel state
581	etc.). None of the active event watchers will be stopped in the normal	643	etc.). None of the active event watchers will be stopped in the normal
582	sense, so e.g. C<ev_is_active> might still return true. It is your	644	sense, so e.g. C<ev_is_active> might still return true. It is your
583	responsibility to either stop all watchers cleanly yourself I<before>	645	responsibility to either stop all watchers cleanly yourself I<before>
584	calling this function, or cope with the fact afterwards (which is usually	646	calling this function, or cope with the fact afterwards (which is usually
585	the easiest thing, you can just ignore the watchers and/or C<free ()> them	647	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
587		649
588	Note that certain global state, such as signal state (and installed signal	650	Note that certain global state, such as signal state (and installed signal
589	handlers), will not be freed by this function, and related watchers (such	651	handlers), will not be freed by this function, and related watchers (such
590	as signal and child watchers) would need to be stopped manually.	652	as signal and child watchers) would need to be stopped manually.
591		653
592	In general it is not advisable to call this function except in the	654	This function is normally used on loop objects allocated by
593	rare occasion where you really need to free e.g. the signal handling	655	C<ev_loop_new>, but it can also be used on the default loop returned by
		656	C<ev_default_loop>, in which case it is not thread-safe.
		657
		658	Note that it is not advisable to call this function on the default loop
		659	except in the rare occasion where you really need to free its resources.
594	pipe fds. If you need dynamically allocated loops it is better to use	660	If you need dynamically allocated loops it is better to use C<ev_loop_new>
595	C<ev_loop_new> and C<ev_loop_destroy>).	661	and C<ev_loop_destroy>.
596		662
597	=item ev_loop_destroy (loop)	663	=item ev_loop_fork (loop)
598		664
599	Like C<ev_default_destroy>, but destroys an event loop created by an
600	earlier call to C<ev_loop_new>.
601
602	=item ev_default_fork ()
603
604	This function sets a flag that causes subsequent C<ev_loop> iterations	665	This function sets a flag that causes subsequent C<ev_run> iterations to
605	to reinitialise the kernel state for backends that have one. Despite the	666	reinitialise the kernel state for backends that have one. Despite the
606	name, you can call it anytime, but it makes most sense after forking, in	667	name, you can call it anytime, but it makes most sense after forking, in
607	the child process (or both child and parent, but that again makes little	668	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
608	sense). You I<must> call it in the child before using any of the libev	669	child before resuming or calling C<ev_run>.
609	functions, and it will only take effect at the next C<ev_loop> iteration.	670
		671	Again, you I<have> to call it on I<any> loop that you want to re-use after
		672	a fork, I<even if you do not plan to use the loop in the parent>. This is
		673	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		674	during fork.
610		675
611	On the other hand, you only need to call this function in the child	676	On the other hand, you only need to call this function in the child
612	process if and only if you want to use the event library in the child. If	677	process if and only if you want to use the event loop in the child. If
613	you just fork+exec, you don't have to call it at all.	678	you just fork+exec or create a new loop in the child, you don't have to
		679	call it at all (in fact, C<epoll> is so badly broken that it makes a
		680	difference, but libev will usually detect this case on its own and do a
		681	costly reset of the backend).
614		682
615	The function itself is quite fast and it's usually not a problem to call	683	The function itself is quite fast and it's usually not a problem to call
616	it just in case after a fork. To make this easy, the function will fit in	684	it just in case after a fork.
617	quite nicely into a call to C<pthread_atfork>:
618		685
		686	Example: Automate calling C<ev_loop_fork> on the default loop when
		687	using pthreads.
		688
		689	static void
		690	post_fork_child (void)
		691	{
		692	ev_loop_fork (EV_DEFAULT);
		693	}
		694
		695	...
619	pthread_atfork (0, 0, ev_default_fork);	696	pthread_atfork (0, 0, post_fork_child);
620
621	=item ev_loop_fork (loop)
622
623	Like C<ev_default_fork>, but acts on an event loop created by
624	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
625	after fork that you want to re-use in the child, and how you do this is
626	entirely your own problem.
627		697
628	=item int ev_is_default_loop (loop)	698	=item int ev_is_default_loop (loop)
629		699
630	Returns true when the given loop is, in fact, the default loop, and false	700	Returns true when the given loop is, in fact, the default loop, and false
631	otherwise.	701	otherwise.
632		702
633	=item unsigned int ev_loop_count (loop)	703	=item unsigned int ev_iteration (loop)
634		704
635	Returns the count of loop iterations for the loop, which is identical to	705	Returns the current iteration count for the event loop, which is identical
636	the number of times libev did poll for new events. It starts at C<0> and	706	to the number of times libev did poll for new events. It starts at C<0>
637	happily wraps around with enough iterations.	707	and happily wraps around with enough iterations.
638		708
639	This value can sometimes be useful as a generation counter of sorts (it	709	This value can sometimes be useful as a generation counter of sorts (it
640	"ticks" the number of loop iterations), as it roughly corresponds with	710	"ticks" the number of loop iterations), as it roughly corresponds with
641	C<ev_prepare> and C<ev_check> calls.	711	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		712	prepare and check phases.
642		713
643	=item unsigned int ev_loop_depth (loop)	714	=item unsigned int ev_depth (loop)
644		715
645	Returns the number of times C<ev_loop> was entered minus the number of	716	Returns the number of times C<ev_run> was entered minus the number of
646	times C<ev_loop> was exited, in other words, the recursion depth.	717	times C<ev_run> was exited normally, in other words, the recursion depth.
647		718
648	Outside C<ev_loop>, this number is zero. In a callback, this number is	719	Outside C<ev_run>, this number is zero. In a callback, this number is
649	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	720	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
650	in which case it is higher.	721	in which case it is higher.
651		722
652	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	723	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
653	etc.), doesn't count as exit.	724	throwing an exception etc.), doesn't count as "exit" - consider this
		725	as a hint to avoid such ungentleman-like behaviour unless it's really
		726	convenient, in which case it is fully supported.
654		727
655	=item unsigned int ev_backend (loop)	728	=item unsigned int ev_backend (loop)
656		729
657	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	730	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
658	use.	731	use.
…		…
667		740
668	=item ev_now_update (loop)	741	=item ev_now_update (loop)
669		742
670	Establishes the current time by querying the kernel, updating the time	743	Establishes the current time by querying the kernel, updating the time
671	returned by C<ev_now ()> in the progress. This is a costly operation and	744	returned by C<ev_now ()> in the progress. This is a costly operation and
672	is usually done automatically within C<ev_loop ()>.	745	is usually done automatically within C<ev_run ()>.
673		746
674	This function is rarely useful, but when some event callback runs for a	747	This function is rarely useful, but when some event callback runs for a
675	very long time without entering the event loop, updating libev's idea of	748	very long time without entering the event loop, updating libev's idea of
676	the current time is a good idea.	749	the current time is a good idea.
677		750
…		…
679		752
680	=item ev_suspend (loop)	753	=item ev_suspend (loop)
681		754
682	=item ev_resume (loop)	755	=item ev_resume (loop)
683		756
684	These two functions suspend and resume a loop, for use when the loop is	757	These two functions suspend and resume an event loop, for use when the
685	not used for a while and timeouts should not be processed.	758	loop is not used for a while and timeouts should not be processed.
686		759
687	A typical use case would be an interactive program such as a game: When	760	A typical use case would be an interactive program such as a game: When
688	the user presses C<^Z> to suspend the game and resumes it an hour later it	761	the user presses C<^Z> to suspend the game and resumes it an hour later it
689	would be best to handle timeouts as if no time had actually passed while	762	would be best to handle timeouts as if no time had actually passed while
690	the program was suspended. This can be achieved by calling C<ev_suspend>	763	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
692	C<ev_resume> directly afterwards to resume timer processing.	765	C<ev_resume> directly afterwards to resume timer processing.
693		766
694	Effectively, all C<ev_timer> watchers will be delayed by the time spend	767	Effectively, all C<ev_timer> watchers will be delayed by the time spend
695	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	768	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
696	will be rescheduled (that is, they will lose any events that would have	769	will be rescheduled (that is, they will lose any events that would have
697	occured while suspended).	770	occurred while suspended).
698		771
699	After calling C<ev_suspend> you B<must not> call I<any> function on the	772	After calling C<ev_suspend> you B<must not> call I<any> function on the
700	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	773	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
701	without a previous call to C<ev_suspend>.	774	without a previous call to C<ev_suspend>.
702		775
703	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	776	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
704	event loop time (see C<ev_now_update>).	777	event loop time (see C<ev_now_update>).
705		778
706	=item ev_loop (loop, int flags)	779	=item ev_run (loop, int flags)
707		780
708	Finally, this is it, the event handler. This function usually is called	781	Finally, this is it, the event handler. This function usually is called
709	after you initialised all your watchers and you want to start handling	782	after you have initialised all your watchers and you want to start
710	events.	783	handling events. It will ask the operating system for any new events, call
		784	the watcher callbacks, an then repeat the whole process indefinitely: This
		785	is why event loops are called I<loops>.
711		786
712	If the flags argument is specified as C<0>, it will not return until	787	If the flags argument is specified as C<0>, it will keep handling events
713	either no event watchers are active anymore or C<ev_unloop> was called.	788	until either no event watchers are active anymore or C<ev_break> was
		789	called.
714		790
715	Please note that an explicit C<ev_unloop> is usually better than	791	Please note that an explicit C<ev_break> is usually better than
716	relying on all watchers to be stopped when deciding when a program has	792	relying on all watchers to be stopped when deciding when a program has
717	finished (especially in interactive programs), but having a program	793	finished (especially in interactive programs), but having a program
718	that automatically loops as long as it has to and no longer by virtue	794	that automatically loops as long as it has to and no longer by virtue
719	of relying on its watchers stopping correctly, that is truly a thing of	795	of relying on its watchers stopping correctly, that is truly a thing of
720	beauty.	796	beauty.
721		797
		798	This function is also I<mostly> exception-safe - you can break out of
		799	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		800	exception and so on. This does not decrement the C<ev_depth> value, nor
		801	will it clear any outstanding C<EVBREAK_ONE> breaks.
		802
722	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	803	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
723	those events and any already outstanding ones, but will not block your	804	those events and any already outstanding ones, but will not wait and
724	process in case there are no events and will return after one iteration of	805	block your process in case there are no events and will return after one
725	the loop.	806	iteration of the loop. This is sometimes useful to poll and handle new
		807	events while doing lengthy calculations, to keep the program responsive.
726		808
727	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	809	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
728	necessary) and will handle those and any already outstanding ones. It	810	necessary) and will handle those and any already outstanding ones. It
729	will block your process until at least one new event arrives (which could	811	will block your process until at least one new event arrives (which could
730	be an event internal to libev itself, so there is no guarantee that a	812	be an event internal to libev itself, so there is no guarantee that a
731	user-registered callback will be called), and will return after one	813	user-registered callback will be called), and will return after one
732	iteration of the loop.	814	iteration of the loop.
733		815
734	This is useful if you are waiting for some external event in conjunction	816	This is useful if you are waiting for some external event in conjunction
735	with something not expressible using other libev watchers (i.e. "roll your	817	with something not expressible using other libev watchers (i.e. "roll your
736	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	818	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
737	usually a better approach for this kind of thing.	819	usually a better approach for this kind of thing.
738		820
739	Here are the gory details of what C<ev_loop> does:	821	Here are the gory details of what C<ev_run> does:
740		822
		823	- Increment loop depth.
		824	- Reset the ev_break status.
741	- Before the first iteration, call any pending watchers.	825	- Before the first iteration, call any pending watchers.
		826	LOOP:
742	* If EVFLAG_FORKCHECK was used, check for a fork.	827	- If EVFLAG_FORKCHECK was used, check for a fork.
743	- If a fork was detected (by any means), queue and call all fork watchers.	828	- If a fork was detected (by any means), queue and call all fork watchers.
744	- Queue and call all prepare watchers.	829	- Queue and call all prepare watchers.
		830	- If ev_break was called, goto FINISH.
745	- If we have been forked, detach and recreate the kernel state	831	- If we have been forked, detach and recreate the kernel state
746	as to not disturb the other process.	832	as to not disturb the other process.
747	- Update the kernel state with all outstanding changes.	833	- Update the kernel state with all outstanding changes.
748	- Update the "event loop time" (ev_now ()).	834	- Update the "event loop time" (ev_now ()).
749	- Calculate for how long to sleep or block, if at all	835	- Calculate for how long to sleep or block, if at all
750	(active idle watchers, EVLOOP_NONBLOCK or not having	836	(active idle watchers, EVRUN_NOWAIT or not having
751	any active watchers at all will result in not sleeping).	837	any active watchers at all will result in not sleeping).
752	- Sleep if the I/O and timer collect interval say so.	838	- Sleep if the I/O and timer collect interval say so.
		839	- Increment loop iteration counter.
753	- Block the process, waiting for any events.	840	- Block the process, waiting for any events.
754	- Queue all outstanding I/O (fd) events.	841	- Queue all outstanding I/O (fd) events.
755	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	842	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
756	- Queue all expired timers.	843	- Queue all expired timers.
757	- Queue all expired periodics.	844	- Queue all expired periodics.
758	- Unless any events are pending now, queue all idle watchers.	845	- Queue all idle watchers with priority higher than that of pending events.
759	- Queue all check watchers.	846	- Queue all check watchers.
760	- Call all queued watchers in reverse order (i.e. check watchers first).	847	- Call all queued watchers in reverse order (i.e. check watchers first).
761	Signals and child watchers are implemented as I/O watchers, and will	848	Signals and child watchers are implemented as I/O watchers, and will
762	be handled here by queueing them when their watcher gets executed.	849	be handled here by queueing them when their watcher gets executed.
763	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	850	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
764	were used, or there are no active watchers, return, otherwise	851	were used, or there are no active watchers, goto FINISH, otherwise
765	continue with step *.	852	continue with step LOOP.
		853	FINISH:
		854	- Reset the ev_break status iff it was EVBREAK_ONE.
		855	- Decrement the loop depth.
		856	- Return.
766		857
767	Example: Queue some jobs and then loop until no events are outstanding	858	Example: Queue some jobs and then loop until no events are outstanding
768	anymore.	859	anymore.
769		860
770	... queue jobs here, make sure they register event watchers as long	861	... queue jobs here, make sure they register event watchers as long
771	... as they still have work to do (even an idle watcher will do..)	862	... as they still have work to do (even an idle watcher will do..)
772	ev_loop (my_loop, 0);	863	ev_run (my_loop, 0);
773	... jobs done or somebody called unloop. yeah!	864	... jobs done or somebody called unloop. yeah!
774		865
775	=item ev_unloop (loop, how)	866	=item ev_break (loop, how)
776		867
777	Can be used to make a call to C<ev_loop> return early (but only after it	868	Can be used to make a call to C<ev_run> return early (but only after it
778	has processed all outstanding events). The C<how> argument must be either	869	has processed all outstanding events). The C<how> argument must be either
779	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	870	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
780	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	871	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
781		872
782	This "unloop state" will be cleared when entering C<ev_loop> again.	873	This "break state" will be cleared on the next call to C<ev_run>.
783		874
784	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	875	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		876	which case it will have no effect.
785		877
786	=item ev_ref (loop)	878	=item ev_ref (loop)
787		879
788	=item ev_unref (loop)	880	=item ev_unref (loop)
789		881
790	Ref/unref can be used to add or remove a reference count on the event	882	Ref/unref can be used to add or remove a reference count on the event
791	loop: Every watcher keeps one reference, and as long as the reference	883	loop: Every watcher keeps one reference, and as long as the reference
792	count is nonzero, C<ev_loop> will not return on its own.	884	count is nonzero, C<ev_run> will not return on its own.
793		885
794	If you have a watcher you never unregister that should not keep C<ev_loop>	886	This is useful when you have a watcher that you never intend to
795	from returning, call ev_unref() after starting, and ev_ref() before	887	unregister, but that nevertheless should not keep C<ev_run> from
		888	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
796	stopping it.	889	before stopping it.
797		890
798	As an example, libev itself uses this for its internal signal pipe: It	891	As an example, libev itself uses this for its internal signal pipe: It
799	is not visible to the libev user and should not keep C<ev_loop> from	892	is not visible to the libev user and should not keep C<ev_run> from
800	exiting if no event watchers registered by it are active. It is also an	893	exiting if no event watchers registered by it are active. It is also an
801	excellent way to do this for generic recurring timers or from within	894	excellent way to do this for generic recurring timers or from within
802	third-party libraries. Just remember to I<unref after start> and I<ref	895	third-party libraries. Just remember to I<unref after start> and I<ref
803	before stop> (but only if the watcher wasn't active before, or was active	896	before stop> (but only if the watcher wasn't active before, or was active
804	before, respectively. Note also that libev might stop watchers itself	897	before, respectively. Note also that libev might stop watchers itself
805	(e.g. non-repeating timers) in which case you have to C<ev_ref>	898	(e.g. non-repeating timers) in which case you have to C<ev_ref>
806	in the callback).	899	in the callback).
807		900
808	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	901	Example: Create a signal watcher, but keep it from keeping C<ev_run>
809	running when nothing else is active.	902	running when nothing else is active.
810		903
811	ev_signal exitsig;	904	ev_signal exitsig;
812	ev_signal_init (&exitsig, sig_cb, SIGINT);	905	ev_signal_init (&exitsig, sig_cb, SIGINT);
813	ev_signal_start (loop, &exitsig);	906	ev_signal_start (loop, &exitsig);
814	evf_unref (loop);	907	ev_unref (loop);
815		908
816	Example: For some weird reason, unregister the above signal handler again.	909	Example: For some weird reason, unregister the above signal handler again.
817		910
818	ev_ref (loop);	911	ev_ref (loop);
819	ev_signal_stop (loop, &exitsig);	912	ev_signal_stop (loop, &exitsig);
…		…
858	usually doesn't make much sense to set it to a lower value than C<0.01>,	951	usually doesn't make much sense to set it to a lower value than C<0.01>,
859	as this approaches the timing granularity of most systems. Note that if	952	as this approaches the timing granularity of most systems. Note that if
860	you do transactions with the outside world and you can't increase the	953	you do transactions with the outside world and you can't increase the
861	parallelity, then this setting will limit your transaction rate (if you	954	parallelity, then this setting will limit your transaction rate (if you
862	need to poll once per transaction and the I/O collect interval is 0.01,	955	need to poll once per transaction and the I/O collect interval is 0.01,
863	then you can't do more than 100 transations per second).	956	then you can't do more than 100 transactions per second).
864		957
865	Setting the I<timeout collect interval> can improve the opportunity for	958	Setting the I<timeout collect interval> can improve the opportunity for
866	saving power, as the program will "bundle" timer callback invocations that	959	saving power, as the program will "bundle" timer callback invocations that
867	are "near" in time together, by delaying some, thus reducing the number of	960	are "near" in time together, by delaying some, thus reducing the number of
868	times the process sleeps and wakes up again. Another useful technique to	961	times the process sleeps and wakes up again. Another useful technique to
…		…
876	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	969	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
877		970
878	=item ev_invoke_pending (loop)	971	=item ev_invoke_pending (loop)
879		972
880	This call will simply invoke all pending watchers while resetting their	973	This call will simply invoke all pending watchers while resetting their
881	pending state. Normally, C<ev_loop> does this automatically when required,	974	pending state. Normally, C<ev_run> does this automatically when required,
882	but when overriding the invoke callback this call comes handy.	975	but when overriding the invoke callback this call comes handy. This
		976	function can be invoked from a watcher - this can be useful for example
		977	when you want to do some lengthy calculation and want to pass further
		978	event handling to another thread (you still have to make sure only one
		979	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
883		980
884	=item int ev_pending_count (loop)	981	=item int ev_pending_count (loop)
885		982
886	Returns the number of pending watchers - zero indicates that no watchers	983	Returns the number of pending watchers - zero indicates that no watchers
887	are pending.	984	are pending.
888		985
889	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	986	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
890		987
891	This overrides the invoke pending functionality of the loop: Instead of	988	This overrides the invoke pending functionality of the loop: Instead of
892	invoking all pending watchers when there are any, C<ev_loop> will call	989	invoking all pending watchers when there are any, C<ev_run> will call
893	this callback instead. This is useful, for example, when you want to	990	this callback instead. This is useful, for example, when you want to
894	invoke the actual watchers inside another context (another thread etc.).	991	invoke the actual watchers inside another context (another thread etc.).
895		992
896	If you want to reset the callback, use C<ev_invoke_pending> as new	993	If you want to reset the callback, use C<ev_invoke_pending> as new
897	callback.	994	callback.
…		…
900		997
901	Sometimes you want to share the same loop between multiple threads. This	998	Sometimes you want to share the same loop between multiple threads. This
902	can be done relatively simply by putting mutex_lock/unlock calls around	999	can be done relatively simply by putting mutex_lock/unlock calls around
903	each call to a libev function.	1000	each call to a libev function.
904		1001
905	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1002	However, C<ev_run> can run an indefinite time, so it is not feasible
906	wait for it to return. One way around this is to wake up the loop via	1003	to wait for it to return. One way around this is to wake up the event
907	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	1004	loop via C<ev_break> and C<av_async_send>, another way is to set these
908	and I<acquire> callbacks on the loop.	1005	I<release> and I<acquire> callbacks on the loop.
909		1006
910	When set, then C<release> will be called just before the thread is	1007	When set, then C<release> will be called just before the thread is
911	suspended waiting for new events, and C<acquire> is called just	1008	suspended waiting for new events, and C<acquire> is called just
912	afterwards.	1009	afterwards.
913		1010
…		…
916		1013
917	While event loop modifications are allowed between invocations of	1014	While event loop modifications are allowed between invocations of
918	C<release> and C<acquire> (that's their only purpose after all), no	1015	C<release> and C<acquire> (that's their only purpose after all), no
919	modifications done will affect the event loop, i.e. adding watchers will	1016	modifications done will affect the event loop, i.e. adding watchers will
920	have no effect on the set of file descriptors being watched, or the time	1017	have no effect on the set of file descriptors being watched, or the time
921	waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it	1018	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
922	to take note of any changes you made.	1019	to take note of any changes you made.
923		1020
924	In theory, threads executing C<ev_loop> will be async-cancel safe between	1021	In theory, threads executing C<ev_run> will be async-cancel safe between
925	invocations of C<release> and C<acquire>.	1022	invocations of C<release> and C<acquire>.
926		1023
927	See also the locking example in the C<THREADS> section later in this	1024	See also the locking example in the C<THREADS> section later in this
928	document.	1025	document.
929		1026
930	=item ev_set_userdata (loop, void *data)	1027	=item ev_set_userdata (loop, void *data)
931		1028
932	=item ev_userdata (loop)	1029	=item void *ev_userdata (loop)
933		1030
934	Set and retrieve a single C<void *> associated with a loop. When	1031	Set and retrieve a single C<void *> associated with a loop. When
935	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1032	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
936	C<0.>	1033	C<0>.
937		1034
938	These two functions can be used to associate arbitrary data with a loop,	1035	These two functions can be used to associate arbitrary data with a loop,
939	and are intended solely for the C<invoke_pending_cb>, C<release> and	1036	and are intended solely for the C<invoke_pending_cb>, C<release> and
940	C<acquire> callbacks described above, but of course can be (ab-)used for	1037	C<acquire> callbacks described above, but of course can be (ab-)used for
941	any other purpose as well.	1038	any other purpose as well.
942		1039
943	=item ev_loop_verify (loop)	1040	=item ev_verify (loop)
944		1041
945	This function only does something when C<EV_VERIFY> support has been	1042	This function only does something when C<EV_VERIFY> support has been
946	compiled in, which is the default for non-minimal builds. It tries to go	1043	compiled in, which is the default for non-minimal builds. It tries to go
947	through all internal structures and checks them for validity. If anything	1044	through all internal structures and checks them for validity. If anything
948	is found to be inconsistent, it will print an error message to standard	1045	is found to be inconsistent, it will print an error message to standard
…		…
959		1056
960	In the following description, uppercase C<TYPE> in names stands for the	1057	In the following description, uppercase C<TYPE> in names stands for the
961	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1058	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
962	watchers and C<ev_io_start> for I/O watchers.	1059	watchers and C<ev_io_start> for I/O watchers.
963		1060
964	A watcher is a structure that you create and register to record your	1061	A watcher is an opaque structure that you allocate and register to record
965	interest in some event. For instance, if you want to wait for STDIN to	1062	your interest in some event. To make a concrete example, imagine you want
966	become readable, you would create an C<ev_io> watcher for that:	1063	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1064	for that:
967		1065
968	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1066	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
969	{	1067	{
970	ev_io_stop (w);	1068	ev_io_stop (w);
971	ev_unloop (loop, EVUNLOOP_ALL);	1069	ev_break (loop, EVBREAK_ALL);
972	}	1070	}
973		1071
974	struct ev_loop *loop = ev_default_loop (0);	1072	struct ev_loop *loop = ev_default_loop (0);
975		1073
976	ev_io stdin_watcher;	1074	ev_io stdin_watcher;
977		1075
978	ev_init (&stdin_watcher, my_cb);	1076	ev_init (&stdin_watcher, my_cb);
979	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1077	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
980	ev_io_start (loop, &stdin_watcher);	1078	ev_io_start (loop, &stdin_watcher);
981		1079
982	ev_loop (loop, 0);	1080	ev_run (loop, 0);
983		1081
984	As you can see, you are responsible for allocating the memory for your	1082	As you can see, you are responsible for allocating the memory for your
985	watcher structures (and it is I<usually> a bad idea to do this on the	1083	watcher structures (and it is I<usually> a bad idea to do this on the
986	stack).	1084	stack).
987		1085
988	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1086	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
989	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1087	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
990		1088
991	Each watcher structure must be initialised by a call to C<ev_init	1089	Each watcher structure must be initialised by a call to C<ev_init (watcher
992	(watcher *, callback)>, which expects a callback to be provided. This	1090	*, callback)>, which expects a callback to be provided. This callback is
993	callback gets invoked each time the event occurs (or, in the case of I/O	1091	invoked each time the event occurs (or, in the case of I/O watchers, each
994	watchers, each time the event loop detects that the file descriptor given	1092	time the event loop detects that the file descriptor given is readable
995	is readable and/or writable).	1093	and/or writable).
996		1094
997	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1095	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
998	macro to configure it, with arguments specific to the watcher type. There	1096	macro to configure it, with arguments specific to the watcher type. There
999	is also a macro to combine initialisation and setting in one call: C<<	1097	is also a macro to combine initialisation and setting in one call: C<<
1000	ev_TYPE_init (watcher *, callback, ...) >>.	1098	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1023	=item C<EV_WRITE>	1121	=item C<EV_WRITE>
1024		1122
1025	The file descriptor in the C<ev_io> watcher has become readable and/or	1123	The file descriptor in the C<ev_io> watcher has become readable and/or
1026	writable.	1124	writable.
1027		1125
1028	=item C<EV_TIMEOUT>	1126	=item C<EV_TIMER>
1029		1127
1030	The C<ev_timer> watcher has timed out.	1128	The C<ev_timer> watcher has timed out.
1031		1129
1032	=item C<EV_PERIODIC>	1130	=item C<EV_PERIODIC>
1033		1131
…		…
1051		1149
1052	=item C<EV_PREPARE>	1150	=item C<EV_PREPARE>
1053		1151
1054	=item C<EV_CHECK>	1152	=item C<EV_CHECK>
1055		1153
1056	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1154	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1057	to gather new events, and all C<ev_check> watchers are invoked just after	1155	to gather new events, and all C<ev_check> watchers are invoked just after
1058	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1156	C<ev_run> has gathered them, but before it invokes any callbacks for any
1059	received events. Callbacks of both watcher types can start and stop as	1157	received events. Callbacks of both watcher types can start and stop as
1060	many watchers as they want, and all of them will be taken into account	1158	many watchers as they want, and all of them will be taken into account
1061	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1159	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1062	C<ev_loop> from blocking).	1160	C<ev_run> from blocking).
1063		1161
1064	=item C<EV_EMBED>	1162	=item C<EV_EMBED>
1065		1163
1066	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1164	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1067		1165
1068	=item C<EV_FORK>	1166	=item C<EV_FORK>
1069		1167
1070	The event loop has been resumed in the child process after fork (see	1168	The event loop has been resumed in the child process after fork (see
1071	C<ev_fork>).	1169	C<ev_fork>).
		1170
		1171	=item C<EV_CLEANUP>
		1172
		1173	The event loop is about to be destroyed (see C<ev_cleanup>).
1072		1174
1073	=item C<EV_ASYNC>	1175	=item C<EV_ASYNC>
1074		1176
1075	The given async watcher has been asynchronously notified (see C<ev_async>).	1177	The given async watcher has been asynchronously notified (see C<ev_async>).
1076		1178
…		…
1123		1225
1124	ev_io w;	1226	ev_io w;
1125	ev_init (&w, my_cb);	1227	ev_init (&w, my_cb);
1126	ev_io_set (&w, STDIN_FILENO, EV_READ);	1228	ev_io_set (&w, STDIN_FILENO, EV_READ);
1127		1229
1128	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1230	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1129		1231
1130	This macro initialises the type-specific parts of a watcher. You need to	1232	This macro initialises the type-specific parts of a watcher. You need to
1131	call C<ev_init> at least once before you call this macro, but you can	1233	call C<ev_init> at least once before you call this macro, but you can
1132	call C<ev_TYPE_set> any number of times. You must not, however, call this	1234	call C<ev_TYPE_set> any number of times. You must not, however, call this
1133	macro on a watcher that is active (it can be pending, however, which is a	1235	macro on a watcher that is active (it can be pending, however, which is a
…		…
1146		1248
1147	Example: Initialise and set an C<ev_io> watcher in one step.	1249	Example: Initialise and set an C<ev_io> watcher in one step.
1148		1250
1149	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1251	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1150		1252
1151	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	1253	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1152		1254
1153	Starts (activates) the given watcher. Only active watchers will receive	1255	Starts (activates) the given watcher. Only active watchers will receive
1154	events. If the watcher is already active nothing will happen.	1256	events. If the watcher is already active nothing will happen.
1155		1257
1156	Example: Start the C<ev_io> watcher that is being abused as example in this	1258	Example: Start the C<ev_io> watcher that is being abused as example in this
1157	whole section.	1259	whole section.
1158		1260
1159	ev_io_start (EV_DEFAULT_UC, &w);	1261	ev_io_start (EV_DEFAULT_UC, &w);
1160		1262
1161	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)	1263	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1162		1264
1163	Stops the given watcher if active, and clears the pending status (whether	1265	Stops the given watcher if active, and clears the pending status (whether
1164	the watcher was active or not).	1266	the watcher was active or not).
1165		1267
1166	It is possible that stopped watchers are pending - for example,	1268	It is possible that stopped watchers are pending - for example,
…		…
1191	=item ev_cb_set (ev_TYPE *watcher, callback)	1293	=item ev_cb_set (ev_TYPE *watcher, callback)
1192		1294
1193	Change the callback. You can change the callback at virtually any time	1295	Change the callback. You can change the callback at virtually any time
1194	(modulo threads).	1296	(modulo threads).
1195		1297
1196	=item ev_set_priority (ev_TYPE *watcher, priority)	1298	=item ev_set_priority (ev_TYPE *watcher, int priority)
1197		1299
1198	=item int ev_priority (ev_TYPE *watcher)	1300	=item int ev_priority (ev_TYPE *watcher)
1199		1301
1200	Set and query the priority of the watcher. The priority is a small	1302	Set and query the priority of the watcher. The priority is a small
1201	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>	1303	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
…		…
1233	watcher isn't pending it does nothing and returns C<0>.	1335	watcher isn't pending it does nothing and returns C<0>.
1234		1336
1235	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1337	Sometimes it can be useful to "poll" a watcher instead of waiting for its
1236	callback to be invoked, which can be accomplished with this function.	1338	callback to be invoked, which can be accomplished with this function.
1237		1339
		1340	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1341
		1342	Feeds the given event set into the event loop, as if the specified event
		1343	had happened for the specified watcher (which must be a pointer to an
		1344	initialised but not necessarily started event watcher). Obviously you must
		1345	not free the watcher as long as it has pending events.
		1346
		1347	Stopping the watcher, letting libev invoke it, or calling
		1348	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1349	not started in the first place.
		1350
		1351	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1352	functions that do not need a watcher.
		1353
1238	=back	1354	=back
1239
1240		1355
1241	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1356	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1242		1357
1243	Each watcher has, by default, a member C<void *data> that you can change	1358	Each watcher has, by default, a member C<void *data> that you can change
1244	and read at any time: libev will completely ignore it. This can be used	1359	and read at any time: libev will completely ignore it. This can be used
…		…
1300	t2_cb (EV_P_ ev_timer *w, int revents)	1415	t2_cb (EV_P_ ev_timer *w, int revents)
1301	{	1416	{
1302	struct my_biggy big = (struct my_biggy *)	1417	struct my_biggy big = (struct my_biggy *)
1303	(((char *)w) - offsetof (struct my_biggy, t2));	1418	(((char *)w) - offsetof (struct my_biggy, t2));
1304	}	1419	}
		1420
		1421	=head2 WATCHER STATES
		1422
		1423	There are various watcher states mentioned throughout this manual -
		1424	active, pending and so on. In this section these states and the rules to
		1425	transition between them will be described in more detail - and while these
		1426	rules might look complicated, they usually do "the right thing".
		1427
		1428	=over 4
		1429
		1430	=item initialiased
		1431
		1432	Before a watcher can be registered with the event looop it has to be
		1433	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1434	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1435
		1436	In this state it is simply some block of memory that is suitable for use
		1437	in an event loop. It can be moved around, freed, reused etc. at will.
		1438
		1439	=item started/running/active
		1440
		1441	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1442	property of the event loop, and is actively waiting for events. While in
		1443	this state it cannot be accessed (except in a few documented ways), moved,
		1444	freed or anything else - the only legal thing is to keep a pointer to it,
		1445	and call libev functions on it that are documented to work on active watchers.
		1446
		1447	=item pending
		1448
		1449	If a watcher is active and libev determines that an event it is interested
		1450	in has occurred (such as a timer expiring), it will become pending. It will
		1451	stay in this pending state until either it is stopped or its callback is
		1452	about to be invoked, so it is not normally pending inside the watcher
		1453	callback.
		1454
		1455	The watcher might or might not be active while it is pending (for example,
		1456	an expired non-repeating timer can be pending but no longer active). If it
		1457	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1458	but it is still property of the event loop at this time, so cannot be
		1459	moved, freed or reused. And if it is active the rules described in the
		1460	previous item still apply.
		1461
		1462	It is also possible to feed an event on a watcher that is not active (e.g.
		1463	via C<ev_feed_event>), in which case it becomes pending without being
		1464	active.
		1465
		1466	=item stopped
		1467
		1468	A watcher can be stopped implicitly by libev (in which case it might still
		1469	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1470	latter will clear any pending state the watcher might be in, regardless
		1471	of whether it was active or not, so stopping a watcher explicitly before
		1472	freeing it is often a good idea.
		1473
		1474	While stopped (and not pending) the watcher is essentially in the
		1475	initialised state, that is it can be reused, moved, modified in any way
		1476	you wish.
		1477
		1478	=back
1305		1479
1306	=head2 WATCHER PRIORITY MODELS	1480	=head2 WATCHER PRIORITY MODELS
1307		1481
1308	Many event loops support I<watcher priorities>, which are usually small	1482	Many event loops support I<watcher priorities>, which are usually small
1309	integers that influence the ordering of event callback invocation	1483	integers that influence the ordering of event callback invocation
…		…
1352		1526
1353	For example, to emulate how many other event libraries handle priorities,	1527	For example, to emulate how many other event libraries handle priorities,
1354	you can associate an C<ev_idle> watcher to each such watcher, and in	1528	you can associate an C<ev_idle> watcher to each such watcher, and in
1355	the normal watcher callback, you just start the idle watcher. The real	1529	the normal watcher callback, you just start the idle watcher. The real
1356	processing is done in the idle watcher callback. This causes libev to	1530	processing is done in the idle watcher callback. This causes libev to
1357	continously poll and process kernel event data for the watcher, but when	1531	continuously poll and process kernel event data for the watcher, but when
1358	the lock-out case is known to be rare (which in turn is rare :), this is	1532	the lock-out case is known to be rare (which in turn is rare :), this is
1359	workable.	1533	workable.
1360		1534
1361	Usually, however, the lock-out model implemented that way will perform	1535	Usually, however, the lock-out model implemented that way will perform
1362	miserably under the type of load it was designed to handle. In that case,	1536	miserably under the type of load it was designed to handle. In that case,
…		…
1376	{	1550	{
1377	// stop the I/O watcher, we received the event, but	1551	// stop the I/O watcher, we received the event, but
1378	// are not yet ready to handle it.	1552	// are not yet ready to handle it.
1379	ev_io_stop (EV_A_ w);	1553	ev_io_stop (EV_A_ w);
1380		1554
1381	// start the idle watcher to ahndle the actual event.	1555	// start the idle watcher to handle the actual event.
1382	// it will not be executed as long as other watchers	1556	// it will not be executed as long as other watchers
1383	// with the default priority are receiving events.	1557	// with the default priority are receiving events.
1384	ev_idle_start (EV_A_ &idle);	1558	ev_idle_start (EV_A_ &idle);
1385	}	1559	}
1386		1560
…		…
1440		1614
1441	If you cannot use non-blocking mode, then force the use of a	1615	If you cannot use non-blocking mode, then force the use of a
1442	known-to-be-good backend (at the time of this writing, this includes only	1616	known-to-be-good backend (at the time of this writing, this includes only
1443	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1617	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1444	descriptors for which non-blocking operation makes no sense (such as	1618	descriptors for which non-blocking operation makes no sense (such as
1445	files) - libev doesn't guarentee any specific behaviour in that case.	1619	files) - libev doesn't guarantee any specific behaviour in that case.
1446		1620
1447	Another thing you have to watch out for is that it is quite easy to	1621	Another thing you have to watch out for is that it is quite easy to
1448	receive "spurious" readiness notifications, that is your callback might	1622	receive "spurious" readiness notifications, that is your callback might
1449	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1623	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1450	because there is no data. Not only are some backends known to create a	1624	because there is no data. Not only are some backends known to create a
…		…
1515		1689
1516	So when you encounter spurious, unexplained daemon exits, make sure you	1690	So when you encounter spurious, unexplained daemon exits, make sure you
1517	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1691	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1518	somewhere, as that would have given you a big clue).	1692	somewhere, as that would have given you a big clue).
1519		1693
		1694	=head3 The special problem of accept()ing when you can't
		1695
		1696	Many implementations of the POSIX C<accept> function (for example,
		1697	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1698	connection from the pending queue in all error cases.
		1699
		1700	For example, larger servers often run out of file descriptors (because
		1701	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1702	rejecting the connection, leading to libev signalling readiness on
		1703	the next iteration again (the connection still exists after all), and
		1704	typically causing the program to loop at 100% CPU usage.
		1705
		1706	Unfortunately, the set of errors that cause this issue differs between
		1707	operating systems, there is usually little the app can do to remedy the
		1708	situation, and no known thread-safe method of removing the connection to
		1709	cope with overload is known (to me).
		1710
		1711	One of the easiest ways to handle this situation is to just ignore it
		1712	- when the program encounters an overload, it will just loop until the
		1713	situation is over. While this is a form of busy waiting, no OS offers an
		1714	event-based way to handle this situation, so it's the best one can do.
		1715
		1716	A better way to handle the situation is to log any errors other than
		1717	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1718	messages, and continue as usual, which at least gives the user an idea of
		1719	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1720	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1721	usage.
		1722
		1723	If your program is single-threaded, then you could also keep a dummy file
		1724	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1725	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1726	close that fd, and create a new dummy fd. This will gracefully refuse
		1727	clients under typical overload conditions.
		1728
		1729	The last way to handle it is to simply log the error and C<exit>, as
		1730	is often done with C<malloc> failures, but this results in an easy
		1731	opportunity for a DoS attack.
1520		1732
1521	=head3 Watcher-Specific Functions	1733	=head3 Watcher-Specific Functions
1522		1734
1523	=over 4	1735	=over 4
1524		1736
…		…
1556	...	1768	...
1557	struct ev_loop *loop = ev_default_init (0);	1769	struct ev_loop *loop = ev_default_init (0);
1558	ev_io stdin_readable;	1770	ev_io stdin_readable;
1559	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1771	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1560	ev_io_start (loop, &stdin_readable);	1772	ev_io_start (loop, &stdin_readable);
1561	ev_loop (loop, 0);	1773	ev_run (loop, 0);
1562		1774
1563		1775
1564	=head2 C<ev_timer> - relative and optionally repeating timeouts	1776	=head2 C<ev_timer> - relative and optionally repeating timeouts
1565		1777
1566	Timer watchers are simple relative timers that generate an event after a	1778	Timer watchers are simple relative timers that generate an event after a
…		…
1575	The callback is guaranteed to be invoked only I<after> its timeout has	1787	The callback is guaranteed to be invoked only I<after> its timeout has
1576	passed (not I<at>, so on systems with very low-resolution clocks this	1788	passed (not I<at>, so on systems with very low-resolution clocks this
1577	might introduce a small delay). If multiple timers become ready during the	1789	might introduce a small delay). If multiple timers become ready during the
1578	same loop iteration then the ones with earlier time-out values are invoked	1790	same loop iteration then the ones with earlier time-out values are invoked
1579	before ones of the same priority with later time-out values (but this is	1791	before ones of the same priority with later time-out values (but this is
1580	no longer true when a callback calls C<ev_loop> recursively).	1792	no longer true when a callback calls C<ev_run> recursively).
1581		1793
1582	=head3 Be smart about timeouts	1794	=head3 Be smart about timeouts
1583		1795
1584	Many real-world problems involve some kind of timeout, usually for error	1796	Many real-world problems involve some kind of timeout, usually for error
1585	recovery. A typical example is an HTTP request - if the other side hangs,	1797	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1671	ev_tstamp timeout = last_activity + 60.;	1883	ev_tstamp timeout = last_activity + 60.;
1672		1884
1673	// if last_activity + 60. is older than now, we did time out	1885	// if last_activity + 60. is older than now, we did time out
1674	if (timeout < now)	1886	if (timeout < now)
1675	{	1887	{
1676	// timeout occured, take action	1888	// timeout occurred, take action
1677	}	1889	}
1678	else	1890	else
1679	{	1891	{
1680	// callback was invoked, but there was some activity, re-arm	1892	// callback was invoked, but there was some activity, re-arm
1681	// the watcher to fire in last_activity + 60, which is	1893	// the watcher to fire in last_activity + 60, which is
…		…
1703	to the current time (meaning we just have some activity :), then call the	1915	to the current time (meaning we just have some activity :), then call the
1704	callback, which will "do the right thing" and start the timer:	1916	callback, which will "do the right thing" and start the timer:
1705		1917
1706	ev_init (timer, callback);	1918	ev_init (timer, callback);
1707	last_activity = ev_now (loop);	1919	last_activity = ev_now (loop);
1708	callback (loop, timer, EV_TIMEOUT);	1920	callback (loop, timer, EV_TIMER);
1709		1921
1710	And when there is some activity, simply store the current time in	1922	And when there is some activity, simply store the current time in
1711	C<last_activity>, no libev calls at all:	1923	C<last_activity>, no libev calls at all:
1712		1924
1713	last_actiivty = ev_now (loop);	1925	last_activity = ev_now (loop);
1714		1926
1715	This technique is slightly more complex, but in most cases where the	1927	This technique is slightly more complex, but in most cases where the
1716	time-out is unlikely to be triggered, much more efficient.	1928	time-out is unlikely to be triggered, much more efficient.
1717		1929
1718	Changing the timeout is trivial as well (if it isn't hard-coded in the	1930	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1756		1968
1757	=head3 The special problem of time updates	1969	=head3 The special problem of time updates
1758		1970
1759	Establishing the current time is a costly operation (it usually takes at	1971	Establishing the current time is a costly operation (it usually takes at
1760	least two system calls): EV therefore updates its idea of the current	1972	least two system calls): EV therefore updates its idea of the current
1761	time only before and after C<ev_loop> collects new events, which causes a	1973	time only before and after C<ev_run> collects new events, which causes a
1762	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1974	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1763	lots of events in one iteration.	1975	lots of events in one iteration.
1764		1976
1765	The relative timeouts are calculated relative to the C<ev_now ()>	1977	The relative timeouts are calculated relative to the C<ev_now ()>
1766	time. This is usually the right thing as this timestamp refers to the time	1978	time. This is usually the right thing as this timestamp refers to the time
…		…
1837	C<repeat> value), or reset the running timer to the C<repeat> value.	2049	C<repeat> value), or reset the running timer to the C<repeat> value.
1838		2050
1839	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	2051	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1840	usage example.	2052	usage example.
1841		2053
1842	=item ev_timer_remaining (loop, ev_timer *)	2054	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
1843		2055
1844	Returns the remaining time until a timer fires. If the timer is active,	2056	Returns the remaining time until a timer fires. If the timer is active,
1845	then this time is relative to the current event loop time, otherwise it's	2057	then this time is relative to the current event loop time, otherwise it's
1846	the timeout value currently configured.	2058	the timeout value currently configured.
1847		2059
1848	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns	2060	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
1849	C<5>. When the timer is started and one second passes, C<ev_timer_remain>	2061	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
1850	will return C<4>. When the timer expires and is restarted, it will return	2062	will return C<4>. When the timer expires and is restarted, it will return
1851	roughly C<7> (likely slightly less as callback invocation takes some time,	2063	roughly C<7> (likely slightly less as callback invocation takes some time,
1852	too), and so on.	2064	too), and so on.
1853		2065
1854	=item ev_tstamp repeat [read-write]	2066	=item ev_tstamp repeat [read-write]
…		…
1883	}	2095	}
1884		2096
1885	ev_timer mytimer;	2097	ev_timer mytimer;
1886	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2098	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1887	ev_timer_again (&mytimer); /* start timer */	2099	ev_timer_again (&mytimer); /* start timer */
1888	ev_loop (loop, 0);	2100	ev_run (loop, 0);
1889		2101
1890	// and in some piece of code that gets executed on any "activity":	2102	// and in some piece of code that gets executed on any "activity":
1891	// reset the timeout to start ticking again at 10 seconds	2103	// reset the timeout to start ticking again at 10 seconds
1892	ev_timer_again (&mytimer);	2104	ev_timer_again (&mytimer);
1893		2105
…		…
1919		2131
1920	As with timers, the callback is guaranteed to be invoked only when the	2132	As with timers, the callback is guaranteed to be invoked only when the
1921	point in time where it is supposed to trigger has passed. If multiple	2133	point in time where it is supposed to trigger has passed. If multiple
1922	timers become ready during the same loop iteration then the ones with	2134	timers become ready during the same loop iteration then the ones with
1923	earlier time-out values are invoked before ones with later time-out values	2135	earlier time-out values are invoked before ones with later time-out values
1924	(but this is no longer true when a callback calls C<ev_loop> recursively).	2136	(but this is no longer true when a callback calls C<ev_run> recursively).
1925		2137
1926	=head3 Watcher-Specific Functions and Data Members	2138	=head3 Watcher-Specific Functions and Data Members
1927		2139
1928	=over 4	2140	=over 4
1929		2141
…		…
2057	Example: Call a callback every hour, or, more precisely, whenever the	2269	Example: Call a callback every hour, or, more precisely, whenever the
2058	system time is divisible by 3600. The callback invocation times have	2270	system time is divisible by 3600. The callback invocation times have
2059	potentially a lot of jitter, but good long-term stability.	2271	potentially a lot of jitter, but good long-term stability.
2060		2272
2061	static void	2273	static void
2062	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2274	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2063	{	2275	{
2064	... its now a full hour (UTC, or TAI or whatever your clock follows)	2276	... its now a full hour (UTC, or TAI or whatever your clock follows)
2065	}	2277	}
2066		2278
2067	ev_periodic hourly_tick;	2279	ev_periodic hourly_tick;
…		…
2090		2302
2091	=head2 C<ev_signal> - signal me when a signal gets signalled!	2303	=head2 C<ev_signal> - signal me when a signal gets signalled!
2092		2304
2093	Signal watchers will trigger an event when the process receives a specific	2305	Signal watchers will trigger an event when the process receives a specific
2094	signal one or more times. Even though signals are very asynchronous, libev	2306	signal one or more times. Even though signals are very asynchronous, libev
2095	will try it's best to deliver signals synchronously, i.e. as part of the	2307	will try its best to deliver signals synchronously, i.e. as part of the
2096	normal event processing, like any other event.	2308	normal event processing, like any other event.
2097		2309
2098	If you want signals to be delivered truly asynchronously, just use	2310	If you want signals to be delivered truly asynchronously, just use
2099	C<sigaction> as you would do without libev and forget about sharing	2311	C<sigaction> as you would do without libev and forget about sharing
2100	the signal. You can even use C<ev_async> from a signal handler to	2312	the signal. You can even use C<ev_async> from a signal handler to
…		…
2108		2320
2109	When the first watcher gets started will libev actually register something	2321	When the first watcher gets started will libev actually register something
2110	with the kernel (thus it coexists with your own signal handlers as long as	2322	with the kernel (thus it coexists with your own signal handlers as long as
2111	you don't register any with libev for the same signal).	2323	you don't register any with libev for the same signal).
2112		2324
2113	Both the signal mask state (C<sigprocmask>) and the signal handler state
2114	(C<sigaction>) are unspecified after starting a signal watcher (and after
2115	sotpping it again), that is, libev might or might not block the signal,
2116	and might or might not set or restore the installed signal handler.
2117
2118	If possible and supported, libev will install its handlers with	2325	If possible and supported, libev will install its handlers with
2119	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should	2326	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2120	not be unduly interrupted. If you have a problem with system calls getting	2327	not be unduly interrupted. If you have a problem with system calls getting
2121	interrupted by signals you can block all signals in an C<ev_check> watcher	2328	interrupted by signals you can block all signals in an C<ev_check> watcher
2122	and unblock them in an C<ev_prepare> watcher.	2329	and unblock them in an C<ev_prepare> watcher.
2123		2330
		2331	=head3 The special problem of inheritance over fork/execve/pthread_create
		2332
		2333	Both the signal mask (C<sigprocmask>) and the signal disposition
		2334	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2335	stopping it again), that is, libev might or might not block the signal,
		2336	and might or might not set or restore the installed signal handler.
		2337
		2338	While this does not matter for the signal disposition (libev never
		2339	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
		2340	C<execve>), this matters for the signal mask: many programs do not expect
		2341	certain signals to be blocked.
		2342
		2343	This means that before calling C<exec> (from the child) you should reset
		2344	the signal mask to whatever "default" you expect (all clear is a good
		2345	choice usually).
		2346
		2347	The simplest way to ensure that the signal mask is reset in the child is
		2348	to install a fork handler with C<pthread_atfork> that resets it. That will
		2349	catch fork calls done by libraries (such as the libc) as well.
		2350
		2351	In current versions of libev, the signal will not be blocked indefinitely
		2352	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2353	the window of opportunity for problems, it will not go away, as libev
		2354	I<has> to modify the signal mask, at least temporarily.
		2355
		2356	So I can't stress this enough: I<If you do not reset your signal mask when
		2357	you expect it to be empty, you have a race condition in your code>. This
		2358	is not a libev-specific thing, this is true for most event libraries.
		2359
		2360	=head3 The special problem of threads signal handling
		2361
		2362	POSIX threads has problematic signal handling semantics, specifically,
		2363	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2364	threads in a process block signals, which is hard to achieve.
		2365
		2366	When you want to use sigwait (or mix libev signal handling with your own
		2367	for the same signals), you can tackle this problem by globally blocking
		2368	all signals before creating any threads (or creating them with a fully set
		2369	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2370	loops. Then designate one thread as "signal receiver thread" which handles
		2371	these signals. You can pass on any signals that libev might be interested
		2372	in by calling C<ev_feed_signal>.
		2373
2124	=head3 Watcher-Specific Functions and Data Members	2374	=head3 Watcher-Specific Functions and Data Members
2125		2375
2126	=over 4	2376	=over 4
2127		2377
2128	=item ev_signal_init (ev_signal *, callback, int signum)	2378	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2143	Example: Try to exit cleanly on SIGINT.	2393	Example: Try to exit cleanly on SIGINT.
2144		2394
2145	static void	2395	static void
2146	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2396	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2147	{	2397	{
2148	ev_unloop (loop, EVUNLOOP_ALL);	2398	ev_break (loop, EVBREAK_ALL);
2149	}	2399	}
2150		2400
2151	ev_signal signal_watcher;	2401	ev_signal signal_watcher;
2152	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2402	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2153	ev_signal_start (loop, &signal_watcher);	2403	ev_signal_start (loop, &signal_watcher);
…		…
2539		2789
2540	Prepare and check watchers are usually (but not always) used in pairs:	2790	Prepare and check watchers are usually (but not always) used in pairs:
2541	prepare watchers get invoked before the process blocks and check watchers	2791	prepare watchers get invoked before the process blocks and check watchers
2542	afterwards.	2792	afterwards.
2543		2793
2544	You I<must not> call C<ev_loop> or similar functions that enter	2794	You I<must not> call C<ev_run> or similar functions that enter
2545	the current event loop from either C<ev_prepare> or C<ev_check>	2795	the current event loop from either C<ev_prepare> or C<ev_check>
2546	watchers. Other loops than the current one are fine, however. The	2796	watchers. Other loops than the current one are fine, however. The
2547	rationale behind this is that you do not need to check for recursion in	2797	rationale behind this is that you do not need to check for recursion in
2548	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2798	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2549	C<ev_check> so if you have one watcher of each kind they will always be	2799	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2717		2967
2718	if (timeout >= 0)	2968	if (timeout >= 0)
2719	// create/start timer	2969	// create/start timer
2720		2970
2721	// poll	2971	// poll
2722	ev_loop (EV_A_ 0);	2972	ev_run (EV_A_ 0);
2723		2973
2724	// stop timer again	2974	// stop timer again
2725	if (timeout >= 0)	2975	if (timeout >= 0)
2726	ev_timer_stop (EV_A_ &to);	2976	ev_timer_stop (EV_A_ &to);
2727		2977
…		…
2805	if you do not want that, you need to temporarily stop the embed watcher).	3055	if you do not want that, you need to temporarily stop the embed watcher).
2806		3056
2807	=item ev_embed_sweep (loop, ev_embed *)	3057	=item ev_embed_sweep (loop, ev_embed *)
2808		3058
2809	Make a single, non-blocking sweep over the embedded loop. This works	3059	Make a single, non-blocking sweep over the embedded loop. This works
2810	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3060	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2811	appropriate way for embedded loops.	3061	appropriate way for embedded loops.
2812		3062
2813	=item struct ev_loop *other [read-only]	3063	=item struct ev_loop *other [read-only]
2814		3064
2815	The embedded event loop.	3065	The embedded event loop.
…		…
2875	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3125	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2876	handlers will be invoked, too, of course.	3126	handlers will be invoked, too, of course.
2877		3127
2878	=head3 The special problem of life after fork - how is it possible?	3128	=head3 The special problem of life after fork - how is it possible?
2879		3129
2880	Most uses of C<fork()> consist of forking, then some simple calls to ste	3130	Most uses of C<fork()> consist of forking, then some simple calls to set
2881	up/change the process environment, followed by a call to C<exec()>. This	3131	up/change the process environment, followed by a call to C<exec()>. This
2882	sequence should be handled by libev without any problems.	3132	sequence should be handled by libev without any problems.
2883		3133
2884	This changes when the application actually wants to do event handling	3134	This changes when the application actually wants to do event handling
2885	in the child, or both parent in child, in effect "continuing" after the	3135	in the child, or both parent in child, in effect "continuing" after the
…		…
2901	disadvantage of having to use multiple event loops (which do not support	3151	disadvantage of having to use multiple event loops (which do not support
2902	signal watchers).	3152	signal watchers).
2903		3153
2904	When this is not possible, or you want to use the default loop for	3154	When this is not possible, or you want to use the default loop for
2905	other reasons, then in the process that wants to start "fresh", call	3155	other reasons, then in the process that wants to start "fresh", call
2906	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3156	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2907	the default loop will "orphan" (not stop) all registered watchers, so you	3157	Destroying the default loop will "orphan" (not stop) all registered
2908	have to be careful not to execute code that modifies those watchers. Note	3158	watchers, so you have to be careful not to execute code that modifies
2909	also that in that case, you have to re-register any signal watchers.	3159	those watchers. Note also that in that case, you have to re-register any
		3160	signal watchers.
2910		3161
2911	=head3 Watcher-Specific Functions and Data Members	3162	=head3 Watcher-Specific Functions and Data Members
2912		3163
2913	=over 4	3164	=over 4
2914		3165
2915	=item ev_fork_init (ev_signal *, callback)	3166	=item ev_fork_init (ev_fork *, callback)
2916		3167
2917	Initialises and configures the fork watcher - it has no parameters of any	3168	Initialises and configures the fork watcher - it has no parameters of any
2918	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3169	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
2919	believe me.	3170	really.
2920		3171
2921	=back	3172	=back
2922		3173
2923		3174
		3175	=head2 C<ev_cleanup> - even the best things end
		3176
		3177	Cleanup watchers are called just before the event loop is being destroyed
		3178	by a call to C<ev_loop_destroy>.
		3179
		3180	While there is no guarantee that the event loop gets destroyed, cleanup
		3181	watchers provide a convenient method to install cleanup hooks for your
		3182	program, worker threads and so on - you just to make sure to destroy the
		3183	loop when you want them to be invoked.
		3184
		3185	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3186	all other watchers, they do not keep a reference to the event loop (which
		3187	makes a lot of sense if you think about it). Like all other watchers, you
		3188	can call libev functions in the callback, except C<ev_cleanup_start>.
		3189
		3190	=head3 Watcher-Specific Functions and Data Members
		3191
		3192	=over 4
		3193
		3194	=item ev_cleanup_init (ev_cleanup *, callback)
		3195
		3196	Initialises and configures the cleanup watcher - it has no parameters of
		3197	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3198	pointless, I assure you.
		3199
		3200	=back
		3201
		3202	Example: Register an atexit handler to destroy the default loop, so any
		3203	cleanup functions are called.
		3204
		3205	static void
		3206	program_exits (void)
		3207	{
		3208	ev_loop_destroy (EV_DEFAULT_UC);
		3209	}
		3210
		3211	...
		3212	atexit (program_exits);
		3213
		3214
2924	=head2 C<ev_async> - how to wake up another event loop	3215	=head2 C<ev_async> - how to wake up an event loop
2925		3216
2926	In general, you cannot use an C<ev_loop> from multiple threads or other	3217	In general, you cannot use an C<ev_run> from multiple threads or other
2927	asynchronous sources such as signal handlers (as opposed to multiple event	3218	asynchronous sources such as signal handlers (as opposed to multiple event
2928	loops - those are of course safe to use in different threads).	3219	loops - those are of course safe to use in different threads).
2929		3220
2930	Sometimes, however, you need to wake up another event loop you do not	3221	Sometimes, however, you need to wake up an event loop you do not control,
2931	control, for example because it belongs to another thread. This is what	3222	for example because it belongs to another thread. This is what C<ev_async>
2932	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3223	watchers do: as long as the C<ev_async> watcher is active, you can signal
2933	can signal it by calling C<ev_async_send>, which is thread- and signal	3224	it by calling C<ev_async_send>, which is thread- and signal safe.
2934	safe.
2935		3225
2936	This functionality is very similar to C<ev_signal> watchers, as signals,	3226	This functionality is very similar to C<ev_signal> watchers, as signals,
2937	too, are asynchronous in nature, and signals, too, will be compressed	3227	too, are asynchronous in nature, and signals, too, will be compressed
2938	(i.e. the number of callback invocations may be less than the number of	3228	(i.e. the number of callback invocations may be less than the number of
2939	C<ev_async_sent> calls).	3229	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3230	of "global async watchers" by using a watcher on an otherwise unused
		3231	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3232	even without knowing which loop owns the signal.
2940		3233
2941	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3234	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
2942	just the default loop.	3235	just the default loop.
2943		3236
2944	=head3 Queueing	3237	=head3 Queueing
2945		3238
2946	C<ev_async> does not support queueing of data in any way. The reason	3239	C<ev_async> does not support queueing of data in any way. The reason
2947	is that the author does not know of a simple (or any) algorithm for a	3240	is that the author does not know of a simple (or any) algorithm for a
2948	multiple-writer-single-reader queue that works in all cases and doesn't	3241	multiple-writer-single-reader queue that works in all cases and doesn't
2949	need elaborate support such as pthreads.	3242	need elaborate support such as pthreads or unportable memory access
		3243	semantics.
2950		3244
2951	That means that if you want to queue data, you have to provide your own	3245	That means that if you want to queue data, you have to provide your own
2952	queue. But at least I can tell you how to implement locking around your	3246	queue. But at least I can tell you how to implement locking around your
2953	queue:	3247	queue:
2954		3248
…		…
3093		3387
3094	If C<timeout> is less than 0, then no timeout watcher will be	3388	If C<timeout> is less than 0, then no timeout watcher will be
3095	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3389	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3096	repeat = 0) will be started. C<0> is a valid timeout.	3390	repeat = 0) will be started. C<0> is a valid timeout.
3097		3391
3098	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3392	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3099	passed an C<revents> set like normal event callbacks (a combination of	3393	passed an C<revents> set like normal event callbacks (a combination of
3100	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3394	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3101	value passed to C<ev_once>. Note that it is possible to receive I<both>	3395	value passed to C<ev_once>. Note that it is possible to receive I<both>
3102	a timeout and an io event at the same time - you probably should give io	3396	a timeout and an io event at the same time - you probably should give io
3103	events precedence.	3397	events precedence.
3104		3398
3105	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3399	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3106		3400
3107	static void stdin_ready (int revents, void *arg)	3401	static void stdin_ready (int revents, void *arg)
3108	{	3402	{
3109	if (revents & EV_READ)	3403	if (revents & EV_READ)
3110	/* stdin might have data for us, joy! */;	3404	/* stdin might have data for us, joy! */;
3111	else if (revents & EV_TIMEOUT)	3405	else if (revents & EV_TIMER)
3112	/* doh, nothing entered */;	3406	/* doh, nothing entered */;
3113	}	3407	}
3114		3408
3115	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3409	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3116		3410
3117	=item ev_feed_event (struct ev_loop *, watcher *, int revents)
3118
3119	Feeds the given event set into the event loop, as if the specified event
3120	had happened for the specified watcher (which must be a pointer to an
3121	initialised but not necessarily started event watcher).
3122
3123	=item ev_feed_fd_event (struct ev_loop *, int fd, int revents)	3411	=item ev_feed_fd_event (loop, int fd, int revents)
3124		3412
3125	Feed an event on the given fd, as if a file descriptor backend detected	3413	Feed an event on the given fd, as if a file descriptor backend detected
3126	the given events it.	3414	the given events it.
3127		3415
3128	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3416	=item ev_feed_signal_event (loop, int signum)
3129		3417
3130	Feed an event as if the given signal occurred (C<loop> must be the default	3418	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3131	loop!).	3419	which is async-safe.
		3420
		3421	=back
		3422
		3423
		3424	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3425
		3426	This section explains some common idioms that are not immediately
		3427	obvious. Note that examples are sprinkled over the whole manual, and this
		3428	section only contains stuff that wouldn't fit anywhere else.
		3429
		3430	=over 4
		3431
		3432	=item Model/nested event loop invocations and exit conditions.
		3433
		3434	Often (especially in GUI toolkits) there are places where you have
		3435	I<modal> interaction, which is most easily implemented by recursively
		3436	invoking C<ev_run>.
		3437
		3438	This brings the problem of exiting - a callback might want to finish the
		3439	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3440	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3441	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3442	other combination: In these cases, C<ev_break> will not work alone.
		3443
		3444	The solution is to maintain "break this loop" variable for each C<ev_run>
		3445	invocation, and use a loop around C<ev_run> until the condition is
		3446	triggered, using C<EVRUN_ONCE>:
		3447
		3448	// main loop
		3449	int exit_main_loop = 0;
		3450
		3451	while (!exit_main_loop)
		3452	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3453
		3454	// in a model watcher
		3455	int exit_nested_loop = 0;
		3456
		3457	while (!exit_nested_loop)
		3458	ev_run (EV_A_ EVRUN_ONCE);
		3459
		3460	To exit from any of these loops, just set the corresponding exit variable:
		3461
		3462	// exit modal loop
		3463	exit_nested_loop = 1;
		3464
		3465	// exit main program, after modal loop is finished
		3466	exit_main_loop = 1;
		3467
		3468	// exit both
		3469	exit_main_loop = exit_nested_loop = 1;
3132		3470
3133	=back	3471	=back
3134		3472
3135		3473
3136	=head1 LIBEVENT EMULATION	3474	=head1 LIBEVENT EMULATION
3137		3475
3138	Libev offers a compatibility emulation layer for libevent. It cannot	3476	Libev offers a compatibility emulation layer for libevent. It cannot
3139	emulate the internals of libevent, so here are some usage hints:	3477	emulate the internals of libevent, so here are some usage hints:
3140		3478
3141	=over 4	3479	=over 4
		3480
		3481	=item * Only the libevent-1.4.1-beta API is being emulated.
		3482
		3483	This was the newest libevent version available when libev was implemented,
		3484	and is still mostly unchanged in 2010.
3142		3485
3143	=item * Use it by including <event.h>, as usual.	3486	=item * Use it by including <event.h>, as usual.
3144		3487
3145	=item * The following members are fully supported: ev_base, ev_callback,	3488	=item * The following members are fully supported: ev_base, ev_callback,
3146	ev_arg, ev_fd, ev_res, ev_events.	3489	ev_arg, ev_fd, ev_res, ev_events.
…		…
3152	=item * Priorities are not currently supported. Initialising priorities	3495	=item * Priorities are not currently supported. Initialising priorities
3153	will fail and all watchers will have the same priority, even though there	3496	will fail and all watchers will have the same priority, even though there
3154	is an ev_pri field.	3497	is an ev_pri field.
3155		3498
3156	=item * In libevent, the last base created gets the signals, in libev, the	3499	=item * In libevent, the last base created gets the signals, in libev, the
3157	first base created (== the default loop) gets the signals.	3500	base that registered the signal gets the signals.
3158		3501
3159	=item * Other members are not supported.	3502	=item * Other members are not supported.
3160		3503
3161	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3504	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3162	to use the libev header file and library.	3505	to use the libev header file and library.
…		…
3181	Care has been taken to keep the overhead low. The only data member the C++	3524	Care has been taken to keep the overhead low. The only data member the C++
3182	classes add (compared to plain C-style watchers) is the event loop pointer	3525	classes add (compared to plain C-style watchers) is the event loop pointer
3183	that the watcher is associated with (or no additional members at all if	3526	that the watcher is associated with (or no additional members at all if
3184	you disable C<EV_MULTIPLICITY> when embedding libev).	3527	you disable C<EV_MULTIPLICITY> when embedding libev).
3185		3528
3186	Currently, functions, and static and non-static member functions can be	3529	Currently, functions, static and non-static member functions and classes
3187	used as callbacks. Other types should be easy to add as long as they only	3530	with C<operator ()> can be used as callbacks. Other types should be easy
3188	need one additional pointer for context. If you need support for other	3531	to add as long as they only need one additional pointer for context. If
3189	types of functors please contact the author (preferably after implementing	3532	you need support for other types of functors please contact the author
3190	it).	3533	(preferably after implementing it).
3191		3534
3192	Here is a list of things available in the C<ev> namespace:	3535	Here is a list of things available in the C<ev> namespace:
3193		3536
3194	=over 4	3537	=over 4
3195		3538
…		…
3213		3556
3214	=over 4	3557	=over 4
3215		3558
3216	=item ev::TYPE::TYPE ()	3559	=item ev::TYPE::TYPE ()
3217		3560
3218	=item ev::TYPE::TYPE (struct ev_loop *)	3561	=item ev::TYPE::TYPE (loop)
3219		3562
3220	=item ev::TYPE::~TYPE	3563	=item ev::TYPE::~TYPE
3221		3564
3222	The constructor (optionally) takes an event loop to associate the watcher	3565	The constructor (optionally) takes an event loop to associate the watcher
3223	with. If it is omitted, it will use C<EV_DEFAULT>.	3566	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
3256	myclass obj;	3599	myclass obj;
3257	ev::io iow;	3600	ev::io iow;
3258	iow.set <myclass, &myclass::io_cb> (&obj);	3601	iow.set <myclass, &myclass::io_cb> (&obj);
3259		3602
3260	=item w->set (object *)	3603	=item w->set (object *)
3261
3262	This is an B<experimental> feature that might go away in a future version.
3263		3604
3264	This is a variation of a method callback - leaving out the method to call	3605	This is a variation of a method callback - leaving out the method to call
3265	will default the method to C<operator ()>, which makes it possible to use	3606	will default the method to C<operator ()>, which makes it possible to use
3266	functor objects without having to manually specify the C<operator ()> all	3607	functor objects without having to manually specify the C<operator ()> all
3267	the time. Incidentally, you can then also leave out the template argument	3608	the time. Incidentally, you can then also leave out the template argument
…		…
3300	Example: Use a plain function as callback.	3641	Example: Use a plain function as callback.
3301		3642
3302	static void io_cb (ev::io &w, int revents) { }	3643	static void io_cb (ev::io &w, int revents) { }
3303	iow.set <io_cb> ();	3644	iow.set <io_cb> ();
3304		3645
3305	=item w->set (struct ev_loop *)	3646	=item w->set (loop)
3306		3647
3307	Associates a different C<struct ev_loop> with this watcher. You can only	3648	Associates a different C<struct ev_loop> with this watcher. You can only
3308	do this when the watcher is inactive (and not pending either).	3649	do this when the watcher is inactive (and not pending either).
3309		3650
3310	=item w->set ([arguments])	3651	=item w->set ([arguments])
3311		3652
3312	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3653	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3313	called at least once. Unlike the C counterpart, an active watcher gets	3654	method or a suitable start method must be called at least once. Unlike the
3314	automatically stopped and restarted when reconfiguring it with this	3655	C counterpart, an active watcher gets automatically stopped and restarted
3315	method.	3656	when reconfiguring it with this method.
3316		3657
3317	=item w->start ()	3658	=item w->start ()
3318		3659
3319	Starts the watcher. Note that there is no C<loop> argument, as the	3660	Starts the watcher. Note that there is no C<loop> argument, as the
3320	constructor already stores the event loop.	3661	constructor already stores the event loop.
3321		3662
		3663	=item w->start ([arguments])
		3664
		3665	Instead of calling C<set> and C<start> methods separately, it is often
		3666	convenient to wrap them in one call. Uses the same type of arguments as
		3667	the configure C<set> method of the watcher.
		3668
3322	=item w->stop ()	3669	=item w->stop ()
3323		3670
3324	Stops the watcher if it is active. Again, no C<loop> argument.	3671	Stops the watcher if it is active. Again, no C<loop> argument.
3325		3672
3326	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3673	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3338		3685
3339	=back	3686	=back
3340		3687
3341	=back	3688	=back
3342		3689
3343	Example: Define a class with an IO and idle watcher, start one of them in	3690	Example: Define a class with two I/O and idle watchers, start the I/O
3344	the constructor.	3691	watchers in the constructor.
3345		3692
3346	class myclass	3693	class myclass
3347	{	3694	{
3348	ev::io io ; void io_cb (ev::io &w, int revents);	3695	ev::io io ; void io_cb (ev::io &w, int revents);
		3696	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3349	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3697	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3350		3698
3351	myclass (int fd)	3699	myclass (int fd)
3352	{	3700	{
3353	io .set <myclass, &myclass::io_cb > (this);	3701	io .set <myclass, &myclass::io_cb > (this);
		3702	io2 .set <myclass, &myclass::io2_cb > (this);
3354	idle.set <myclass, &myclass::idle_cb> (this);	3703	idle.set <myclass, &myclass::idle_cb> (this);
3355		3704
3356	io.start (fd, ev::READ);	3705	io.set (fd, ev::WRITE); // configure the watcher
		3706	io.start (); // start it whenever convenient
		3707
		3708	io2.start (fd, ev::READ); // set + start in one call
3357	}	3709	}
3358	};	3710	};
3359		3711
3360		3712
3361	=head1 OTHER LANGUAGE BINDINGS	3713	=head1 OTHER LANGUAGE BINDINGS
…		…
3407	=item Ocaml	3759	=item Ocaml
3408		3760
3409	Erkki Seppala has written Ocaml bindings for libev, to be found at	3761	Erkki Seppala has written Ocaml bindings for libev, to be found at
3410	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3762	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3411		3763
		3764	=item Lua
		3765
		3766	Brian Maher has written a partial interface to libev for lua (at the
		3767	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
		3768	L<http://github.com/brimworks/lua-ev>.
		3769
3412	=back	3770	=back
3413		3771
3414		3772
3415	=head1 MACRO MAGIC	3773	=head1 MACRO MAGIC
3416		3774
…		…
3429	loop argument"). The C<EV_A> form is used when this is the sole argument,	3787	loop argument"). The C<EV_A> form is used when this is the sole argument,
3430	C<EV_A_> is used when other arguments are following. Example:	3788	C<EV_A_> is used when other arguments are following. Example:
3431		3789
3432	ev_unref (EV_A);	3790	ev_unref (EV_A);
3433	ev_timer_add (EV_A_ watcher);	3791	ev_timer_add (EV_A_ watcher);
3434	ev_loop (EV_A_ 0);	3792	ev_run (EV_A_ 0);
3435		3793
3436	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3794	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3437	which is often provided by the following macro.	3795	which is often provided by the following macro.
3438		3796
3439	=item C<EV_P>, C<EV_P_>	3797	=item C<EV_P>, C<EV_P_>
…		…
3479	}	3837	}
3480		3838
3481	ev_check check;	3839	ev_check check;
3482	ev_check_init (&check, check_cb);	3840	ev_check_init (&check, check_cb);
3483	ev_check_start (EV_DEFAULT_ &check);	3841	ev_check_start (EV_DEFAULT_ &check);
3484	ev_loop (EV_DEFAULT_ 0);	3842	ev_run (EV_DEFAULT_ 0);
3485		3843
3486	=head1 EMBEDDING	3844	=head1 EMBEDDING
3487		3845
3488	Libev can (and often is) directly embedded into host	3846	Libev can (and often is) directly embedded into host
3489	applications. Examples of applications that embed it include the Deliantra	3847	applications. Examples of applications that embed it include the Deliantra
…		…
3569	libev.m4	3927	libev.m4
3570		3928
3571	=head2 PREPROCESSOR SYMBOLS/MACROS	3929	=head2 PREPROCESSOR SYMBOLS/MACROS
3572		3930
3573	Libev can be configured via a variety of preprocessor symbols you have to	3931	Libev can be configured via a variety of preprocessor symbols you have to
3574	define before including any of its files. The default in the absence of	3932	define before including (or compiling) any of its files. The default in
3575	autoconf is documented for every option.	3933	the absence of autoconf is documented for every option.
		3934
		3935	Symbols marked with "(h)" do not change the ABI, and can have different
		3936	values when compiling libev vs. including F<ev.h>, so it is permissible
		3937	to redefine them before including F<ev.h> without breaking compatibility
		3938	to a compiled library. All other symbols change the ABI, which means all
		3939	users of libev and the libev code itself must be compiled with compatible
		3940	settings.
3576		3941
3577	=over 4	3942	=over 4
3578		3943
		3944	=item EV_COMPAT3 (h)
		3945
		3946	Backwards compatibility is a major concern for libev. This is why this
		3947	release of libev comes with wrappers for the functions and symbols that
		3948	have been renamed between libev version 3 and 4.
		3949
		3950	You can disable these wrappers (to test compatibility with future
		3951	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3952	sources. This has the additional advantage that you can drop the C<struct>
		3953	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3954	typedef in that case.
		3955
		3956	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3957	and in some even more future version the compatibility code will be
		3958	removed completely.
		3959
3579	=item EV_STANDALONE	3960	=item EV_STANDALONE (h)
3580		3961
3581	Must always be C<1> if you do not use autoconf configuration, which	3962	Must always be C<1> if you do not use autoconf configuration, which
3582	keeps libev from including F<config.h>, and it also defines dummy	3963	keeps libev from including F<config.h>, and it also defines dummy
3583	implementations for some libevent functions (such as logging, which is not	3964	implementations for some libevent functions (such as logging, which is not
3584	supported). It will also not define any of the structs usually found in	3965	supported). It will also not define any of the structs usually found in
…		…
3657	be used is the winsock select). This means that it will call	4038	be used is the winsock select). This means that it will call
3658	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	4039	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
3659	it is assumed that all these functions actually work on fds, even	4040	it is assumed that all these functions actually work on fds, even
3660	on win32. Should not be defined on non-win32 platforms.	4041	on win32. Should not be defined on non-win32 platforms.
3661		4042
3662	=item EV_FD_TO_WIN32_HANDLE	4043	=item EV_FD_TO_WIN32_HANDLE(fd)
3663		4044
3664	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map	4045	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
3665	file descriptors to socket handles. When not defining this symbol (the	4046	file descriptors to socket handles. When not defining this symbol (the
3666	default), then libev will call C<_get_osfhandle>, which is usually	4047	default), then libev will call C<_get_osfhandle>, which is usually
3667	correct. In some cases, programs use their own file descriptor management,	4048	correct. In some cases, programs use their own file descriptor management,
3668	in which case they can provide this function to map fds to socket handles.	4049	in which case they can provide this function to map fds to socket handles.
		4050
		4051	=item EV_WIN32_HANDLE_TO_FD(handle)
		4052
		4053	If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors
		4054	using the standard C<_open_osfhandle> function. For programs implementing
		4055	their own fd to handle mapping, overwriting this function makes it easier
		4056	to do so. This can be done by defining this macro to an appropriate value.
		4057
		4058	=item EV_WIN32_CLOSE_FD(fd)
		4059
		4060	If programs implement their own fd to handle mapping on win32, then this
		4061	macro can be used to override the C<close> function, useful to unregister
		4062	file descriptors again. Note that the replacement function has to close
		4063	the underlying OS handle.
3669		4064
3670	=item EV_USE_POLL	4065	=item EV_USE_POLL
3671		4066
3672	If defined to be C<1>, libev will compile in support for the C<poll>(2)	4067	If defined to be C<1>, libev will compile in support for the C<poll>(2)
3673	backend. Otherwise it will be enabled on non-win32 platforms. It	4068	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
3720	as well as for signal and thread safety in C<ev_async> watchers.	4115	as well as for signal and thread safety in C<ev_async> watchers.
3721		4116
3722	In the absence of this define, libev will use C<sig_atomic_t volatile>	4117	In the absence of this define, libev will use C<sig_atomic_t volatile>
3723	(from F<signal.h>), which is usually good enough on most platforms.	4118	(from F<signal.h>), which is usually good enough on most platforms.
3724		4119
3725	=item EV_H	4120	=item EV_H (h)
3726		4121
3727	The name of the F<ev.h> header file used to include it. The default if	4122	The name of the F<ev.h> header file used to include it. The default if
3728	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	4123	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3729	used to virtually rename the F<ev.h> header file in case of conflicts.	4124	used to virtually rename the F<ev.h> header file in case of conflicts.
3730		4125
3731	=item EV_CONFIG_H	4126	=item EV_CONFIG_H (h)
3732		4127
3733	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4128	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3734	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	4129	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3735	C<EV_H>, above.	4130	C<EV_H>, above.
3736		4131
3737	=item EV_EVENT_H	4132	=item EV_EVENT_H (h)
3738		4133
3739	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4134	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3740	of how the F<event.h> header can be found, the default is C<"event.h">.	4135	of how the F<event.h> header can be found, the default is C<"event.h">.
3741		4136
3742	=item EV_PROTOTYPES	4137	=item EV_PROTOTYPES (h)
3743		4138
3744	If defined to be C<0>, then F<ev.h> will not define any function	4139	If defined to be C<0>, then F<ev.h> will not define any function
3745	prototypes, but still define all the structs and other symbols. This is	4140	prototypes, but still define all the structs and other symbols. This is
3746	occasionally useful if you want to provide your own wrapper functions	4141	occasionally useful if you want to provide your own wrapper functions
3747	around libev functions.	4142	around libev functions.
…		…
3769	fine.	4164	fine.
3770		4165
3771	If your embedding application does not need any priorities, defining these	4166	If your embedding application does not need any priorities, defining these
3772	both to C<0> will save some memory and CPU.	4167	both to C<0> will save some memory and CPU.
3773		4168
3774	=item EV_PERIODIC_ENABLE	4169	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4170	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4171	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3775		4172
3776	If undefined or defined to be C<1>, then periodic timers are supported. If	4173	If undefined or defined to be C<1> (and the platform supports it), then
3777	defined to be C<0>, then they are not. Disabling them saves a few kB of	4174	the respective watcher type is supported. If defined to be C<0>, then it
3778	code.	4175	is not. Disabling watcher types mainly saves code size.
3779		4176
3780	=item EV_IDLE_ENABLE	4177	=item EV_FEATURES
3781
3782	If undefined or defined to be C<1>, then idle watchers are supported. If
3783	defined to be C<0>, then they are not. Disabling them saves a few kB of
3784	code.
3785
3786	=item EV_EMBED_ENABLE
3787
3788	If undefined or defined to be C<1>, then embed watchers are supported. If
3789	defined to be C<0>, then they are not. Embed watchers rely on most other
3790	watcher types, which therefore must not be disabled.
3791
3792	=item EV_STAT_ENABLE
3793
3794	If undefined or defined to be C<1>, then stat watchers are supported. If
3795	defined to be C<0>, then they are not.
3796
3797	=item EV_FORK_ENABLE
3798
3799	If undefined or defined to be C<1>, then fork watchers are supported. If
3800	defined to be C<0>, then they are not.
3801
3802	=item EV_ASYNC_ENABLE
3803
3804	If undefined or defined to be C<1>, then async watchers are supported. If
3805	defined to be C<0>, then they are not.
3806
3807	=item EV_MINIMAL
3808		4178
3809	If you need to shave off some kilobytes of code at the expense of some	4179	If you need to shave off some kilobytes of code at the expense of some
3810	speed (but with the full API), define this symbol to C<1>. Currently this	4180	speed (but with the full API), you can define this symbol to request
3811	is used to override some inlining decisions, saves roughly 30% code size	4181	certain subsets of functionality. The default is to enable all features
3812	on amd64. It also selects a much smaller 2-heap for timer management over	4182	that can be enabled on the platform.
3813	the default 4-heap.
3814		4183
3815	You can save even more by disabling watcher types you do not need	4184	A typical way to use this symbol is to define it to C<0> (or to a bitset
3816	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	4185	with some broad features you want) and then selectively re-enable
3817	(C<-DNDEBUG>) will usually reduce code size a lot.	4186	additional parts you want, for example if you want everything minimal,
		4187	but multiple event loop support, async and child watchers and the poll
		4188	backend, use this:
3818		4189
3819	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4190	#define EV_FEATURES 0
3820	provide a bare-bones event library. See C<ev.h> for details on what parts	4191	#define EV_MULTIPLICITY 1
3821	of the API are still available, and do not complain if this subset changes	4192	#define EV_USE_POLL 1
3822	over time.	4193	#define EV_CHILD_ENABLE 1
		4194	#define EV_ASYNC_ENABLE 1
		4195
		4196	The actual value is a bitset, it can be a combination of the following
		4197	values:
		4198
		4199	=over 4
		4200
		4201	=item C<1> - faster/larger code
		4202
		4203	Use larger code to speed up some operations.
		4204
		4205	Currently this is used to override some inlining decisions (enlarging the
		4206	code size by roughly 30% on amd64).
		4207
		4208	When optimising for size, use of compiler flags such as C<-Os> with
		4209	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4210	assertions.
		4211
		4212	=item C<2> - faster/larger data structures
		4213
		4214	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4215	hash table sizes and so on. This will usually further increase code size
		4216	and can additionally have an effect on the size of data structures at
		4217	runtime.
		4218
		4219	=item C<4> - full API configuration
		4220
		4221	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4222	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4223
		4224	=item C<8> - full API
		4225
		4226	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4227	details on which parts of the API are still available without this
		4228	feature, and do not complain if this subset changes over time.
		4229
		4230	=item C<16> - enable all optional watcher types
		4231
		4232	Enables all optional watcher types. If you want to selectively enable
		4233	only some watcher types other than I/O and timers (e.g. prepare,
		4234	embed, async, child...) you can enable them manually by defining
		4235	C<EV_watchertype_ENABLE> to C<1> instead.
		4236
		4237	=item C<32> - enable all backends
		4238
		4239	This enables all backends - without this feature, you need to enable at
		4240	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4241
		4242	=item C<64> - enable OS-specific "helper" APIs
		4243
		4244	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4245	default.
		4246
		4247	=back
		4248
		4249	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4250	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4251	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4252	watchers, timers and monotonic clock support.
		4253
		4254	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4255	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4256	your program might be left out as well - a binary starting a timer and an
		4257	I/O watcher then might come out at only 5Kb.
		4258
		4259	=item EV_AVOID_STDIO
		4260
		4261	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4262	functions (printf, scanf, perror etc.). This will increase the code size
		4263	somewhat, but if your program doesn't otherwise depend on stdio and your
		4264	libc allows it, this avoids linking in the stdio library which is quite
		4265	big.
		4266
		4267	Note that error messages might become less precise when this option is
		4268	enabled.
3823		4269
3824	=item EV_NSIG	4270	=item EV_NSIG
3825		4271
3826	The highest supported signal number, +1 (or, the number of	4272	The highest supported signal number, +1 (or, the number of
3827	signals): Normally, libev tries to deduce the maximum number of signals	4273	signals): Normally, libev tries to deduce the maximum number of signals
3828	automatically, but sometimes this fails, in which case it can be	4274	automatically, but sometimes this fails, in which case it can be
3829	specified. Also, using a lower number than detected (C<32> should be	4275	specified. Also, using a lower number than detected (C<32> should be
3830	good for about any system in existance) can save some memory, as libev	4276	good for about any system in existence) can save some memory, as libev
3831	statically allocates some 12-24 bytes per signal number.	4277	statically allocates some 12-24 bytes per signal number.
3832		4278
3833	=item EV_PID_HASHSIZE	4279	=item EV_PID_HASHSIZE
3834		4280
3835	C<ev_child> watchers use a small hash table to distribute workload by	4281	C<ev_child> watchers use a small hash table to distribute workload by
3836	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4282	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3837	than enough. If you need to manage thousands of children you might want to	4283	usually more than enough. If you need to manage thousands of children you
3838	increase this value (I<must> be a power of two).	4284	might want to increase this value (I<must> be a power of two).
3839		4285
3840	=item EV_INOTIFY_HASHSIZE	4286	=item EV_INOTIFY_HASHSIZE
3841		4287
3842	C<ev_stat> watchers use a small hash table to distribute workload by	4288	C<ev_stat> watchers use a small hash table to distribute workload by
3843	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4289	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3844	usually more than enough. If you need to manage thousands of C<ev_stat>	4290	disabled), usually more than enough. If you need to manage thousands of
3845	watchers you might want to increase this value (I<must> be a power of	4291	C<ev_stat> watchers you might want to increase this value (I<must> be a
3846	two).	4292	power of two).
3847		4293
3848	=item EV_USE_4HEAP	4294	=item EV_USE_4HEAP
3849		4295
3850	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4296	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3851	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4297	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3852	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4298	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3853	faster performance with many (thousands) of watchers.	4299	faster performance with many (thousands) of watchers.
3854		4300
3855	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4301	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3856	(disabled).	4302	will be C<0>.
3857		4303
3858	=item EV_HEAP_CACHE_AT	4304	=item EV_HEAP_CACHE_AT
3859		4305
3860	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4306	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3861	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4307	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3862	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4308	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3863	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4309	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3864	but avoids random read accesses on heap changes. This improves performance	4310	but avoids random read accesses on heap changes. This improves performance
3865	noticeably with many (hundreds) of watchers.	4311	noticeably with many (hundreds) of watchers.
3866		4312
3867	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4313	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3868	(disabled).	4314	will be C<0>.
3869		4315
3870	=item EV_VERIFY	4316	=item EV_VERIFY
3871		4317
3872	Controls how much internal verification (see C<ev_loop_verify ()>) will	4318	Controls how much internal verification (see C<ev_verify ()>) will
3873	be done: If set to C<0>, no internal verification code will be compiled	4319	be done: If set to C<0>, no internal verification code will be compiled
3874	in. If set to C<1>, then verification code will be compiled in, but not	4320	in. If set to C<1>, then verification code will be compiled in, but not
3875	called. If set to C<2>, then the internal verification code will be	4321	called. If set to C<2>, then the internal verification code will be
3876	called once per loop, which can slow down libev. If set to C<3>, then the	4322	called once per loop, which can slow down libev. If set to C<3>, then the
3877	verification code will be called very frequently, which will slow down	4323	verification code will be called very frequently, which will slow down
3878	libev considerably.	4324	libev considerably.
3879		4325
3880	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4326	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3881	C<0>.	4327	will be C<0>.
3882		4328
3883	=item EV_COMMON	4329	=item EV_COMMON
3884		4330
3885	By default, all watchers have a C<void *data> member. By redefining	4331	By default, all watchers have a C<void *data> member. By redefining
3886	this macro to a something else you can include more and other types of	4332	this macro to something else you can include more and other types of
3887	members. You have to define it each time you include one of the files,	4333	members. You have to define it each time you include one of the files,
3888	though, and it must be identical each time.	4334	though, and it must be identical each time.
3889		4335
3890	For example, the perl EV module uses something like this:	4336	For example, the perl EV module uses something like this:
3891		4337
…		…
3944	file.	4390	file.
3945		4391
3946	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4392	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3947	that everybody includes and which overrides some configure choices:	4393	that everybody includes and which overrides some configure choices:
3948		4394
3949	#define EV_MINIMAL 1	4395	#define EV_FEATURES 8
3950	#define EV_USE_POLL 0	4396	#define EV_USE_SELECT 1
3951	#define EV_MULTIPLICITY 0
3952	#define EV_PERIODIC_ENABLE 0	4397	#define EV_PREPARE_ENABLE 1
		4398	#define EV_IDLE_ENABLE 1
3953	#define EV_STAT_ENABLE 0	4399	#define EV_SIGNAL_ENABLE 1
3954	#define EV_FORK_ENABLE 0	4400	#define EV_CHILD_ENABLE 1
		4401	#define EV_USE_STDEXCEPT 0
3955	#define EV_CONFIG_H <config.h>	4402	#define EV_CONFIG_H <config.h>
3956	#define EV_MINPRI 0
3957	#define EV_MAXPRI 0
3958		4403
3959	#include "ev++.h"	4404	#include "ev++.h"
3960		4405
3961	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4406	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3962		4407
…		…
4093	userdata *u = ev_userdata (EV_A);	4538	userdata *u = ev_userdata (EV_A);
4094	pthread_mutex_lock (&u->lock);	4539	pthread_mutex_lock (&u->lock);
4095	}	4540	}
4096		4541
4097	The event loop thread first acquires the mutex, and then jumps straight	4542	The event loop thread first acquires the mutex, and then jumps straight
4098	into C<ev_loop>:	4543	into C<ev_run>:
4099		4544
4100	void *	4545	void *
4101	l_run (void *thr_arg)	4546	l_run (void *thr_arg)
4102	{	4547	{
4103	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4548	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4104		4549
4105	l_acquire (EV_A);	4550	l_acquire (EV_A);
4106	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4551	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4107	ev_loop (EV_A_ 0);	4552	ev_run (EV_A_ 0);
4108	l_release (EV_A);	4553	l_release (EV_A);
4109		4554
4110	return 0;	4555	return 0;
4111	}	4556	}
4112		4557
…		…
4164		4609
4165	=head3 COROUTINES	4610	=head3 COROUTINES
4166		4611
4167	Libev is very accommodating to coroutines ("cooperative threads"):	4612	Libev is very accommodating to coroutines ("cooperative threads"):
4168	libev fully supports nesting calls to its functions from different	4613	libev fully supports nesting calls to its functions from different
4169	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4614	coroutines (e.g. you can call C<ev_run> on the same loop from two
4170	different coroutines, and switch freely between both coroutines running	4615	different coroutines, and switch freely between both coroutines running
4171	the loop, as long as you don't confuse yourself). The only exception is	4616	the loop, as long as you don't confuse yourself). The only exception is
4172	that you must not do this from C<ev_periodic> reschedule callbacks.	4617	that you must not do this from C<ev_periodic> reschedule callbacks.
4173		4618
4174	Care has been taken to ensure that libev does not keep local state inside	4619	Care has been taken to ensure that libev does not keep local state inside
4175	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4620	C<ev_run>, and other calls do not usually allow for coroutine switches as
4176	they do not call any callbacks.	4621	they do not call any callbacks.
4177		4622
4178	=head2 COMPILER WARNINGS	4623	=head2 COMPILER WARNINGS
4179		4624
4180	Depending on your compiler and compiler settings, you might get no or a	4625	Depending on your compiler and compiler settings, you might get no or a
…		…
4191	maintainable.	4636	maintainable.
4192		4637
4193	And of course, some compiler warnings are just plain stupid, or simply	4638	And of course, some compiler warnings are just plain stupid, or simply
4194	wrong (because they don't actually warn about the condition their message	4639	wrong (because they don't actually warn about the condition their message
4195	seems to warn about). For example, certain older gcc versions had some	4640	seems to warn about). For example, certain older gcc versions had some
4196	warnings that resulted an extreme number of false positives. These have	4641	warnings that resulted in an extreme number of false positives. These have
4197	been fixed, but some people still insist on making code warn-free with	4642	been fixed, but some people still insist on making code warn-free with
4198	such buggy versions.	4643	such buggy versions.
4199		4644
4200	While libev is written to generate as few warnings as possible,	4645	While libev is written to generate as few warnings as possible,
4201	"warn-free" code is not a goal, and it is recommended not to build libev	4646	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4237	I suggest using suppression lists.	4682	I suggest using suppression lists.
4238		4683
4239		4684
4240	=head1 PORTABILITY NOTES	4685	=head1 PORTABILITY NOTES
4241		4686
		4687	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4688
		4689	GNU/Linux is the only common platform that supports 64 bit file/large file
		4690	interfaces but I<disables> them by default.
		4691
		4692	That means that libev compiled in the default environment doesn't support
		4693	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4694
		4695	Unfortunately, many programs try to work around this GNU/Linux issue
		4696	by enabling the large file API, which makes them incompatible with the
		4697	standard libev compiled for their system.
		4698
		4699	Likewise, libev cannot enable the large file API itself as this would
		4700	suddenly make it incompatible to the default compile time environment,
		4701	i.e. all programs not using special compile switches.
		4702
		4703	=head2 OS/X AND DARWIN BUGS
		4704
		4705	The whole thing is a bug if you ask me - basically any system interface
		4706	you touch is broken, whether it is locales, poll, kqueue or even the
		4707	OpenGL drivers.
		4708
		4709	=head3 C<kqueue> is buggy
		4710
		4711	The kqueue syscall is broken in all known versions - most versions support
		4712	only sockets, many support pipes.
		4713
		4714	Libev tries to work around this by not using C<kqueue> by default on this
		4715	rotten platform, but of course you can still ask for it when creating a
		4716	loop - embedding a socket-only kqueue loop into a select-based one is
		4717	probably going to work well.
		4718
		4719	=head3 C<poll> is buggy
		4720
		4721	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4722	implementation by something calling C<kqueue> internally around the 10.5.6
		4723	release, so now C<kqueue> I<and> C<poll> are broken.
		4724
		4725	Libev tries to work around this by not using C<poll> by default on
		4726	this rotten platform, but of course you can still ask for it when creating
		4727	a loop.
		4728
		4729	=head3 C<select> is buggy
		4730
		4731	All that's left is C<select>, and of course Apple found a way to fuck this
		4732	one up as well: On OS/X, C<select> actively limits the number of file
		4733	descriptors you can pass in to 1024 - your program suddenly crashes when
		4734	you use more.
		4735
		4736	There is an undocumented "workaround" for this - defining
		4737	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4738	work on OS/X.
		4739
		4740	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4741
		4742	=head3 C<errno> reentrancy
		4743
		4744	The default compile environment on Solaris is unfortunately so
		4745	thread-unsafe that you can't even use components/libraries compiled
		4746	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4747	defined by default. A valid, if stupid, implementation choice.
		4748
		4749	If you want to use libev in threaded environments you have to make sure
		4750	it's compiled with C<_REENTRANT> defined.
		4751
		4752	=head3 Event port backend
		4753
		4754	The scalable event interface for Solaris is called "event
		4755	ports". Unfortunately, this mechanism is very buggy in all major
		4756	releases. If you run into high CPU usage, your program freezes or you get
		4757	a large number of spurious wakeups, make sure you have all the relevant
		4758	and latest kernel patches applied. No, I don't know which ones, but there
		4759	are multiple ones to apply, and afterwards, event ports actually work
		4760	great.
		4761
		4762	If you can't get it to work, you can try running the program by setting
		4763	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4764	C<select> backends.
		4765
		4766	=head2 AIX POLL BUG
		4767
		4768	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4769	this by trying to avoid the poll backend altogether (i.e. it's not even
		4770	compiled in), which normally isn't a big problem as C<select> works fine
		4771	with large bitsets on AIX, and AIX is dead anyway.
		4772
4242	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4773	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4774
		4775	=head3 General issues
4243		4776
4244	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4777	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4245	requires, and its I/O model is fundamentally incompatible with the POSIX	4778	requires, and its I/O model is fundamentally incompatible with the POSIX
4246	model. Libev still offers limited functionality on this platform in	4779	model. Libev still offers limited functionality on this platform in
4247	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4780	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4248	descriptors. This only applies when using Win32 natively, not when using	4781	descriptors. This only applies when using Win32 natively, not when using
4249	e.g. cygwin.	4782	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4783	as every compielr comes with a slightly differently broken/incompatible
		4784	environment.
4250		4785
4251	Lifting these limitations would basically require the full	4786	Lifting these limitations would basically require the full
4252	re-implementation of the I/O system. If you are into these kinds of	4787	re-implementation of the I/O system. If you are into this kind of thing,
4253	things, then note that glib does exactly that for you in a very portable	4788	then note that glib does exactly that for you in a very portable way (note
4254	way (note also that glib is the slowest event library known to man).	4789	also that glib is the slowest event library known to man).
4255		4790
4256	There is no supported compilation method available on windows except	4791	There is no supported compilation method available on windows except
4257	embedding it into other applications.	4792	embedding it into other applications.
4258		4793
4259	Sensible signal handling is officially unsupported by Microsoft - libev	4794	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4287	you do I<not> compile the F<ev.c> or any other embedded source files!):	4822	you do I<not> compile the F<ev.c> or any other embedded source files!):
4288		4823
4289	#include "evwrap.h"	4824	#include "evwrap.h"
4290	#include "ev.c"	4825	#include "ev.c"
4291		4826
4292	=over 4
4293
4294	=item The winsocket select function	4827	=head3 The winsocket C<select> function
4295		4828
4296	The winsocket C<select> function doesn't follow POSIX in that it	4829	The winsocket C<select> function doesn't follow POSIX in that it
4297	requires socket I<handles> and not socket I<file descriptors> (it is	4830	requires socket I<handles> and not socket I<file descriptors> (it is
4298	also extremely buggy). This makes select very inefficient, and also	4831	also extremely buggy). This makes select very inefficient, and also
4299	requires a mapping from file descriptors to socket handles (the Microsoft	4832	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4308	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4841	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4309		4842
4310	Note that winsockets handling of fd sets is O(n), so you can easily get a	4843	Note that winsockets handling of fd sets is O(n), so you can easily get a
4311	complexity in the O(n²) range when using win32.	4844	complexity in the O(n²) range when using win32.
4312		4845
4313	=item Limited number of file descriptors	4846	=head3 Limited number of file descriptors
4314		4847
4315	Windows has numerous arbitrary (and low) limits on things.	4848	Windows has numerous arbitrary (and low) limits on things.
4316		4849
4317	Early versions of winsocket's select only supported waiting for a maximum	4850	Early versions of winsocket's select only supported waiting for a maximum
4318	of C<64> handles (probably owning to the fact that all windows kernels	4851	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4333	runtime libraries. This might get you to about C<512> or C<2048> sockets	4866	runtime libraries. This might get you to about C<512> or C<2048> sockets
4334	(depending on windows version and/or the phase of the moon). To get more,	4867	(depending on windows version and/or the phase of the moon). To get more,
4335	you need to wrap all I/O functions and provide your own fd management, but	4868	you need to wrap all I/O functions and provide your own fd management, but
4336	the cost of calling select (O(n²)) will likely make this unworkable.	4869	the cost of calling select (O(n²)) will likely make this unworkable.
4337		4870
4338	=back
4339
4340	=head2 PORTABILITY REQUIREMENTS	4871	=head2 PORTABILITY REQUIREMENTS
4341		4872
4342	In addition to a working ISO-C implementation and of course the	4873	In addition to a working ISO-C implementation and of course the
4343	backend-specific APIs, libev relies on a few additional extensions:	4874	backend-specific APIs, libev relies on a few additional extensions:
4344		4875
…		…
4350	Libev assumes not only that all watcher pointers have the same internal	4881	Libev assumes not only that all watcher pointers have the same internal
4351	structure (guaranteed by POSIX but not by ISO C for example), but it also	4882	structure (guaranteed by POSIX but not by ISO C for example), but it also
4352	assumes that the same (machine) code can be used to call any watcher	4883	assumes that the same (machine) code can be used to call any watcher
4353	callback: The watcher callbacks have different type signatures, but libev	4884	callback: The watcher callbacks have different type signatures, but libev
4354	calls them using an C<ev_watcher *> internally.	4885	calls them using an C<ev_watcher *> internally.
		4886
		4887	=item pointer accesses must be thread-atomic
		4888
		4889	Accessing a pointer value must be atomic, it must both be readable and
		4890	writable in one piece - this is the case on all current architectures.
4355		4891
4356	=item C<sig_atomic_t volatile> must be thread-atomic as well	4892	=item C<sig_atomic_t volatile> must be thread-atomic as well
4357		4893
4358	The type C<sig_atomic_t volatile> (or whatever is defined as	4894	The type C<sig_atomic_t volatile> (or whatever is defined as
4359	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4895	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4382	watchers.	4918	watchers.
4383		4919
4384	=item C<double> must hold a time value in seconds with enough accuracy	4920	=item C<double> must hold a time value in seconds with enough accuracy
4385		4921
4386	The type C<double> is used to represent timestamps. It is required to	4922	The type C<double> is used to represent timestamps. It is required to
4387	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4923	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4388	enough for at least into the year 4000. This requirement is fulfilled by	4924	good enough for at least into the year 4000 with millisecond accuracy
		4925	(the design goal for libev). This requirement is overfulfilled by
4389	implementations implementing IEEE 754, which is basically all existing	4926	implementations using IEEE 754, which is basically all existing ones. With
4390	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4927	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4391	2200.
4392		4928
4393	=back	4929	=back
4394		4930
4395	If you know of other additional requirements drop me a note.	4931	If you know of other additional requirements drop me a note.
4396		4932
…		…
4464	involves iterating over all running async watchers or all signal numbers.	5000	involves iterating over all running async watchers or all signal numbers.
4465		5001
4466	=back	5002	=back
4467		5003
4468		5004
		5005	=head1 PORTING FROM LIBEV 3.X TO 4.X
		5006
		5007	The major version 4 introduced some incompatible changes to the API.
		5008
		5009	At the moment, the C<ev.h> header file provides compatibility definitions
		5010	for all changes, so most programs should still compile. The compatibility
		5011	layer might be removed in later versions of libev, so better update to the
		5012	new API early than late.
		5013
		5014	=over 4
		5015
		5016	=item C<EV_COMPAT3> backwards compatibility mechanism
		5017
		5018	The backward compatibility mechanism can be controlled by
		5019	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5020	section.
		5021
		5022	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5023
		5024	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5025
		5026	ev_loop_destroy (EV_DEFAULT_UC);
		5027	ev_loop_fork (EV_DEFAULT);
		5028
		5029	=item function/symbol renames
		5030
		5031	A number of functions and symbols have been renamed:
		5032
		5033	ev_loop => ev_run
		5034	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5035	EVLOOP_ONESHOT => EVRUN_ONCE
		5036
		5037	ev_unloop => ev_break
		5038	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5039	EVUNLOOP_ONE => EVBREAK_ONE
		5040	EVUNLOOP_ALL => EVBREAK_ALL
		5041
		5042	EV_TIMEOUT => EV_TIMER
		5043
		5044	ev_loop_count => ev_iteration
		5045	ev_loop_depth => ev_depth
		5046	ev_loop_verify => ev_verify
		5047
		5048	Most functions working on C<struct ev_loop> objects don't have an
		5049	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5050	associated constants have been renamed to not collide with the C<struct
		5051	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5052	as all other watcher types. Note that C<ev_loop_fork> is still called
		5053	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		5054	typedef.
		5055
		5056	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		5057
		5058	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		5059	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		5060	and work, but the library code will of course be larger.
		5061
		5062	=back
		5063
		5064
4469	=head1 GLOSSARY	5065	=head1 GLOSSARY
4470		5066
4471	=over 4	5067	=over 4
4472		5068
4473	=item active	5069	=item active
4474		5070
4475	A watcher is active as long as it has been started (has been attached to	5071	A watcher is active as long as it has been started and not yet stopped.
4476	an event loop) but not yet stopped (disassociated from the event loop).	5072	See L<WATCHER STATES> for details.
4477		5073
4478	=item application	5074	=item application
4479		5075
4480	In this document, an application is whatever is using libev.	5076	In this document, an application is whatever is using libev.
		5077
		5078	=item backend
		5079
		5080	The part of the code dealing with the operating system interfaces.
4481		5081
4482	=item callback	5082	=item callback
4483		5083
4484	The address of a function that is called when some event has been	5084	The address of a function that is called when some event has been
4485	detected. Callbacks are being passed the event loop, the watcher that	5085	detected. Callbacks are being passed the event loop, the watcher that
4486	received the event, and the actual event bitset.	5086	received the event, and the actual event bitset.
4487		5087
4488	=item callback invocation	5088	=item callback/watcher invocation
4489		5089
4490	The act of calling the callback associated with a watcher.	5090	The act of calling the callback associated with a watcher.
4491		5091
4492	=item event	5092	=item event
4493		5093
4494	A change of state of some external event, such as data now being available	5094	A change of state of some external event, such as data now being available
4495	for reading on a file descriptor, time having passed or simply not having	5095	for reading on a file descriptor, time having passed or simply not having
4496	any other events happening anymore.	5096	any other events happening anymore.
4497		5097
4498	In libev, events are represented as single bits (such as C<EV_READ> or	5098	In libev, events are represented as single bits (such as C<EV_READ> or
4499	C<EV_TIMEOUT>).	5099	C<EV_TIMER>).
4500		5100
4501	=item event library	5101	=item event library
4502		5102
4503	A software package implementing an event model and loop.	5103	A software package implementing an event model and loop.
4504		5104
…		…
4512	The model used to describe how an event loop handles and processes	5112	The model used to describe how an event loop handles and processes
4513	watchers and events.	5113	watchers and events.
4514		5114
4515	=item pending	5115	=item pending
4516		5116
4517	A watcher is pending as soon as the corresponding event has been detected,	5117	A watcher is pending as soon as the corresponding event has been
4518	and stops being pending as soon as the watcher will be invoked or its	5118	detected. See L<WATCHER STATES> for details.
4519	pending status is explicitly cleared by the application.
4520
4521	A watcher can be pending, but not active. Stopping a watcher also clears
4522	its pending status.
4523		5119
4524	=item real time	5120	=item real time
4525		5121
4526	The physical time that is observed. It is apparently strictly monotonic :)	5122	The physical time that is observed. It is apparently strictly monotonic :)
4527		5123
…		…
4534	=item watcher	5130	=item watcher
4535		5131
4536	A data structure that describes interest in certain events. Watchers need	5132	A data structure that describes interest in certain events. Watchers need
4537	to be started (attached to an event loop) before they can receive events.	5133	to be started (attached to an event loop) before they can receive events.
4538		5134
4539	=item watcher invocation
4540
4541	The act of calling the callback associated with a watcher.
4542
4543	=back	5135	=back
4544		5136
4545	=head1 AUTHOR	5137	=head1 AUTHOR
4546		5138
4547	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5139	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5140	Magnusson and Emanuele Giaquinta.
4548		5141

Diff Legend

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