[ViewVC] Diff of: cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.313 by root, Fri Oct 22 05:44:33 2010 UTC vs.
Revision 1.352 by root, Mon Jan 10 14:30:15 2011 UTC

…		…
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);
…		…
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	Familiarity 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
…		…
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 (in practise	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	somewhere near the beginning of 1970, details are complicated, don't	138	somewhere near the beginning of 1970, details are complicated, don't
131	ask). This type is called C<ev_tstamp>, which is what you should use	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	too. It usually aliases to the C<double> type in C. When you need to do	140	too. It usually aliases to the C<double> type in C. When you need to do
133	any calculations on it, you should treat it as some floating point value.	141	any calculations on it, you should treat it as some floating point value.
134		142
…		…
165		173
166	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
167		175
168	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
169	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
170	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>.
171		180
172	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
173		182
174	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
175	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
…		…
192	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
193	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
194	not a problem.	203	not a problem.
195		204
196	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
197	version (note, however, that this will not detect ABI mismatches :).	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
198		208
199	assert (("libev version mismatch",	209	assert (("libev version mismatch",
200	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
201	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
202		212
…		…
213	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
214	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
215		225
216	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
217		227
218	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
219	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
220	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
221	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
222	(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
223	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
224		235
225	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
226		237
227	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
228	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
229	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
230	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
231	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
232		243
233	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
234		245
235	=item ev_set_allocator (void (cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void (cb)(void *ptr, long size))
236		247
237	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
238	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
239	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
240	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
…		…
266	}	277	}
267		278
268	...	279	...
269	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
270		281
271	=item ev_set_syserr_cb (void (cb)(const char msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (cb)(const char msg))
272		283
273	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
274	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
275	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
276	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
…		…
288	}	299	}
289		300
290	...	301	...
291	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
292		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
293	=back	317	=back
294		318
295	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	319	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
296		320
297	An event loop is described by a C<struct ev_loop *> (the C<struct> is	321	An event loop is described by a C<struct ev_loop *> (the C<struct> is
298	I<not> optional in this case unless libev 3 compatibility is disabled, as	322	I<not> optional in this case unless libev 3 compatibility is disabled, as
299	libev 3 had an C<ev_loop> function colliding with the struct name).	323	libev 3 had an C<ev_loop> function colliding with the struct name).
300		324
301	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
302	supports signals and child events, and dynamically created event loops	326	supports child process events, and dynamically created event loops which
303	which do not.	327	do not.
304		328
305	=over 4	329	=over 4
306		330
307	=item struct ev_loop *ev_default_loop (unsigned int flags)	331	=item struct ev_loop *ev_default_loop (unsigned int flags)
308		332
309	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
310	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
311	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
312	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".
313		343
314	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
315	function.	345	function (or via the C<EV_DEFAULT> macro).
316		346
317	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
318	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
319	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).
320		351
321	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,
322	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
323	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
324	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
325	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	356	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
326	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.
327		376
328	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
329	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>).
330		379
331	The following flags are supported:	380	The following flags are supported:
…		…
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_SIGNALFD>	424	=item C<EVFLAG_SIGNALFD>
376		425
377	When this flag is specified, then libev will 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 API	427	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
379	delivers signals synchronously, which makes it both faster and might make	428	delivers signals synchronously, which makes it both faster and might make
380	it possible to get the queued signal data. It can also simplify signal	429	it possible to get the queued signal data. It can also simplify signal
381	handling with threads, as long as you properly block signals in your	430	handling with threads, as long as you properly block signals in your
382	threads that are not interested in handling them.	431	threads that are not interested in handling them.
383		432
384	Signalfd will not be used by default as this changes your signal mask, and	433	Signalfd will not be used by default as this changes your signal mask, and
385	there are a lot of shoddy libraries and programs (glib's threadpool for	434	there are a lot of shoddy libraries and programs (glib's threadpool for
386	example) that can't properly initialise their signal masks.	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.
387		448
388	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
389		450
390	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
391	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,
…		…
427	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
428		489
429	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
430	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
431	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
432	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
433	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
434	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
435	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
436	hard to detect.	499	and is of course hard to detect.
437		500
438	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
439	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
440	I<different> file descriptors (even already closed ones, so one cannot	503	I<different> file descriptors (even already closed ones, so one cannot
441	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
…		…
443	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
444	events to filter out spurious ones, recreating the set when required. Last	507	events to filter out spurious ones, recreating the set when required. Last
445	not least, it also refuses to work with some file descriptors which work	508	not least, it also refuses to work with some file descriptors which work
446	perfectly fine with C<select> (files, many character devices...).	509	perfectly fine with C<select> (files, many character devices...).
447		510
		511	Epoll is truly the train wreck analog among event poll mechanisms.
		512
448	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
449	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
450	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
451	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
452	file descriptors might not work very well if you register events for both	517	file descriptors might not work very well if you register events for both
…		…
517	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	582	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
518		583
519	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,
520	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)).
521		586
522	Please note that Solaris event ports can deliver a lot of spurious
523	notifications, so you need to use non-blocking I/O or other means to avoid
524	blocking when no data (or space) is available.
525
526	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
527	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
528	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	589	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
529	might perform better.	590	might perform better.
530		591
531	On the positive side, with the exception of the spurious readiness	592	On the positive side, this backend actually performed fully to
532	notifications, this backend actually performed fully to specification
533	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
534	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> - so bizarre that
		598	even sun itself gets it wrong in their code examples: The event polling
		599	function sometimes returning events to the caller even though an error
		600	occured, but with no indication whether it has done so or not (yes, it's
		601	even documented that way) - deadly for edge-triggered interfaces where
		602	you absolutely have to know whether an event occured or not because you
		603	have to re-arm the watcher.
		604
		605	Fortunately libev seems to be able to work around these idiocies.
535		606
536	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	607	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
537	C<EVBACKEND_POLL>.	608	C<EVBACKEND_POLL>.
538		609
539	=item C<EVBACKEND_ALL>	610	=item C<EVBACKEND_ALL>
540		611
541	Try all backends (even potentially broken ones that wouldn't be tried	612	Try all backends (even potentially broken ones that wouldn't be tried
542	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	613	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
543	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	614	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
544		615
545	It is definitely not recommended to use this flag.	616	It is definitely not recommended to use this flag, use whatever
		617	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		618	at all.
		619
		620	=item C<EVBACKEND_MASK>
		621
		622	Not a backend at all, but a mask to select all backend bits from a
		623	C<flags> value, in case you want to mask out any backends from a flags
		624	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
546		625
547	=back	626	=back
548		627
549	If one or more of the backend flags are or'ed into the flags value,	628	If one or more of the backend flags are or'ed into the flags value,
550	then only these backends will be tried (in the reverse order as listed	629	then only these backends will be tried (in the reverse order as listed
551	here). If none are specified, all backends in C<ev_recommended_backends	630	here). If none are specified, all backends in C<ev_recommended_backends
552	()> will be tried.	631	()> will be tried.
553		632
554	Example: This is the most typical usage.
555
556	if (!ev_default_loop (0))
557	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
558
559	Example: Restrict libev to the select and poll backends, and do not allow
560	environment settings to be taken into account:
561
562	ev_default_loop (EVBACKEND_POLL \| EVBACKEND_SELECT \| EVFLAG_NOENV);
563
564	Example: Use whatever libev has to offer, but make sure that kqueue is
565	used if available (warning, breaks stuff, best use only with your own
566	private event loop and only if you know the OS supports your types of
567	fds):
568
569	ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);
570
571	=item struct ev_loop *ev_loop_new (unsigned int flags)
572
573	Similar to C<ev_default_loop>, but always creates a new event loop that is
574	always distinct from the default loop.
575
576	Note that this function I<is> thread-safe, and one common way to use
577	libev with threads is indeed to create one loop per thread, and using the
578	default loop in the "main" or "initial" thread.
579
580	Example: Try to create a event loop that uses epoll and nothing else.	633	Example: Try to create a event loop that uses epoll and nothing else.
581		634
582	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	635	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
583	if (!epoller)	636	if (!epoller)
584	fatal ("no epoll found here, maybe it hides under your chair");	637	fatal ("no epoll found here, maybe it hides under your chair");
585		638
		639	Example: Use whatever libev has to offer, but make sure that kqueue is
		640	used if available.
		641
		642	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () \| EVBACKEND_KQUEUE);
		643
586	=item ev_default_destroy ()	644	=item ev_loop_destroy (loop)
587		645
588	Destroys the default loop (frees all memory and kernel state etc.). None	646	Destroys an event loop object (frees all memory and kernel state
589	of the active event watchers will be stopped in the normal sense, so	647	etc.). None of the active event watchers will be stopped in the normal
590	e.g. C<ev_is_active> might still return true. It is your responsibility to	648	sense, so e.g. C<ev_is_active> might still return true. It is your
591	either stop all watchers cleanly yourself I<before> calling this function,	649	responsibility to either stop all watchers cleanly yourself I<before>
592	or cope with the fact afterwards (which is usually the easiest thing, you	650	calling this function, or cope with the fact afterwards (which is usually
593	can just ignore the watchers and/or C<free ()> them for example).	651	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		652	for example).
594		653
595	Note that certain global state, such as signal state (and installed signal	654	Note that certain global state, such as signal state (and installed signal
596	handlers), will not be freed by this function, and related watchers (such	655	handlers), will not be freed by this function, and related watchers (such
597	as signal and child watchers) would need to be stopped manually.	656	as signal and child watchers) would need to be stopped manually.
598		657
599	In general it is not advisable to call this function except in the	658	This function is normally used on loop objects allocated by
600	rare occasion where you really need to free e.g. the signal handling	659	C<ev_loop_new>, but it can also be used on the default loop returned by
		660	C<ev_default_loop>, in which case it is not thread-safe.
		661
		662	Note that it is not advisable to call this function on the default loop
		663	except in the rare occasion where you really need to free its resources.
601	pipe fds. If you need dynamically allocated loops it is better to use	664	If you need dynamically allocated loops it is better to use C<ev_loop_new>
602	C<ev_loop_new> and C<ev_loop_destroy>.	665	and C<ev_loop_destroy>.
603		666
604	=item ev_loop_destroy (loop)	667	=item ev_loop_fork (loop)
605		668
606	Like C<ev_default_destroy>, but destroys an event loop created by an
607	earlier call to C<ev_loop_new>.
608
609	=item ev_default_fork ()
610
611	This function sets a flag that causes subsequent C<ev_run> iterations	669	This function sets a flag that causes subsequent C<ev_run> iterations to
612	to reinitialise the kernel state for backends that have one. Despite the	670	reinitialise the kernel state for backends that have one. Despite the
613	name, you can call it anytime, but it makes most sense after forking, in	671	name, you can call it anytime, but it makes most sense after forking, in
614	the child process (or both child and parent, but that again makes little	672	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
615	sense). You I<must> call it in the child before using any of the libev	673	child before resuming or calling C<ev_run>.
616	functions, and it will only take effect at the next C<ev_run> iteration.
617		674
618	Again, you I<have> to call it on I<any> loop that you want to re-use after	675	Again, you I<have> to call it on I<any> loop that you want to re-use after
619	a fork, I<even if you do not plan to use the loop in the parent>. This is	676	a fork, I<even if you do not plan to use the loop in the parent>. This is
620	because some kernel interfaces cough I<kqueue> cough do funny things	677	because some kernel interfaces cough I<kqueue> cough do funny things
621	during fork.	678	during fork.
…		…
626	call it at all (in fact, C<epoll> is so badly broken that it makes a	683	call it at all (in fact, C<epoll> is so badly broken that it makes a
627	difference, but libev will usually detect this case on its own and do a	684	difference, but libev will usually detect this case on its own and do a
628	costly reset of the backend).	685	costly reset of the backend).
629		686
630	The function itself is quite fast and it's usually not a problem to call	687	The function itself is quite fast and it's usually not a problem to call
631	it just in case after a fork. To make this easy, the function will fit in	688	it just in case after a fork.
632	quite nicely into a call to C<pthread_atfork>:
633		689
		690	Example: Automate calling C<ev_loop_fork> on the default loop when
		691	using pthreads.
		692
		693	static void
		694	post_fork_child (void)
		695	{
		696	ev_loop_fork (EV_DEFAULT);
		697	}
		698
		699	...
634	pthread_atfork (0, 0, ev_default_fork);	700	pthread_atfork (0, 0, post_fork_child);
635
636	=item ev_loop_fork (loop)
637
638	Like C<ev_default_fork>, but acts on an event loop created by
639	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
640	after fork that you want to re-use in the child, and how you keep track of
641	them is entirely your own problem.
642		701
643	=item int ev_is_default_loop (loop)	702	=item int ev_is_default_loop (loop)
644		703
645	Returns true when the given loop is, in fact, the default loop, and false	704	Returns true when the given loop is, in fact, the default loop, and false
646	otherwise.	705	otherwise.
…		…
657	prepare and check phases.	716	prepare and check phases.
658		717
659	=item unsigned int ev_depth (loop)	718	=item unsigned int ev_depth (loop)
660		719
661	Returns the number of times C<ev_run> was entered minus the number of	720	Returns the number of times C<ev_run> was entered minus the number of
662	times C<ev_run> was exited, in other words, the recursion depth.	721	times C<ev_run> was exited normally, in other words, the recursion depth.
663		722
664	Outside C<ev_run>, this number is zero. In a callback, this number is	723	Outside C<ev_run>, this number is zero. In a callback, this number is
665	C<1>, unless C<ev_run> was invoked recursively (or from another thread),	724	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
666	in which case it is higher.	725	in which case it is higher.
667		726
668	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread	727	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
669	etc.), doesn't count as "exit" - consider this as a hint to avoid such	728	throwing an exception etc.), doesn't count as "exit" - consider this
670	ungentleman-like behaviour unless it's really convenient.	729	as a hint to avoid such ungentleman-like behaviour unless it's really
		730	convenient, in which case it is fully supported.
671		731
672	=item unsigned int ev_backend (loop)	732	=item unsigned int ev_backend (loop)
673		733
674	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	734	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
675	use.	735	use.
…		…
736	relying on all watchers to be stopped when deciding when a program has	796	relying on all watchers to be stopped when deciding when a program has
737	finished (especially in interactive programs), but having a program	797	finished (especially in interactive programs), but having a program
738	that automatically loops as long as it has to and no longer by virtue	798	that automatically loops as long as it has to and no longer by virtue
739	of relying on its watchers stopping correctly, that is truly a thing of	799	of relying on its watchers stopping correctly, that is truly a thing of
740	beauty.	800	beauty.
		801
		802	This function is also I<mostly> exception-safe - you can break out of
		803	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		804	exception and so on. This does not decrement the C<ev_depth> value, nor
		805	will it clear any outstanding C<EVBREAK_ONE> breaks.
741		806
742	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle	807	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
743	those events and any already outstanding ones, but will not wait and	808	those events and any already outstanding ones, but will not wait and
744	block your process in case there are no events and will return after one	809	block your process in case there are no events and will return after one
745	iteration of the loop. This is sometimes useful to poll and handle new	810	iteration of the loop. This is sometimes useful to poll and handle new
…		…
807	Can be used to make a call to C<ev_run> return early (but only after it	872	Can be used to make a call to C<ev_run> return early (but only after it
808	has processed all outstanding events). The C<how> argument must be either	873	has processed all outstanding events). The C<how> argument must be either
809	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or	874	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
810	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.	875	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
811		876
812	This "unloop state" will be cleared when entering C<ev_run> again.	877	This "break state" will be cleared on the next call to C<ev_run>.
813		878
814	It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO##	879	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		880	which case it will have no effect.
815		881
816	=item ev_ref (loop)	882	=item ev_ref (loop)
817		883
818	=item ev_unref (loop)	884	=item ev_unref (loop)
819		885
…		…
840	running when nothing else is active.	906	running when nothing else is active.
841		907
842	ev_signal exitsig;	908	ev_signal exitsig;
843	ev_signal_init (&exitsig, sig_cb, SIGINT);	909	ev_signal_init (&exitsig, sig_cb, SIGINT);
844	ev_signal_start (loop, &exitsig);	910	ev_signal_start (loop, &exitsig);
845	evf_unref (loop);	911	ev_unref (loop);
846		912
847	Example: For some weird reason, unregister the above signal handler again.	913	Example: For some weird reason, unregister the above signal handler again.
848		914
849	ev_ref (loop);	915	ev_ref (loop);
850	ev_signal_stop (loop, &exitsig);	916	ev_signal_stop (loop, &exitsig);
…		…
962	See also the locking example in the C<THREADS> section later in this	1028	See also the locking example in the C<THREADS> section later in this
963	document.	1029	document.
964		1030
965	=item ev_set_userdata (loop, void *data)	1031	=item ev_set_userdata (loop, void *data)
966		1032
967	=item ev_userdata (loop)	1033	=item void *ev_userdata (loop)
968		1034
969	Set and retrieve a single C<void *> associated with a loop. When	1035	Set and retrieve a single C<void *> associated with a loop. When
970	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1036	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
971	C<0.>	1037	C<0>.
972		1038
973	These two functions can be used to associate arbitrary data with a loop,	1039	These two functions can be used to associate arbitrary data with a loop,
974	and are intended solely for the C<invoke_pending_cb>, C<release> and	1040	and are intended solely for the C<invoke_pending_cb>, C<release> and
975	C<acquire> callbacks described above, but of course can be (ab-)used for	1041	C<acquire> callbacks described above, but of course can be (ab-)used for
976	any other purpose as well.	1042	any other purpose as well.
…		…
1104	=item C<EV_FORK>	1170	=item C<EV_FORK>
1105		1171
1106	The event loop has been resumed in the child process after fork (see	1172	The event loop has been resumed in the child process after fork (see
1107	C<ev_fork>).	1173	C<ev_fork>).
1108		1174
		1175	=item C<EV_CLEANUP>
		1176
		1177	The event loop is about to be destroyed (see C<ev_cleanup>).
		1178
1109	=item C<EV_ASYNC>	1179	=item C<EV_ASYNC>
1110		1180
1111	The given async watcher has been asynchronously notified (see C<ev_async>).	1181	The given async watcher has been asynchronously notified (see C<ev_async>).
1112		1182
1113	=item C<EV_CUSTOM>	1183	=item C<EV_CUSTOM>
…		…
1134	programs, though, as the fd could already be closed and reused for another	1204	programs, though, as the fd could already be closed and reused for another
1135	thing, so beware.	1205	thing, so beware.
1136		1206
1137	=back	1207	=back
1138		1208
1139	=head2 WATCHER STATES
1140
1141	There are various watcher states mentioned throughout this manual -
1142	active, pending and so on. In this section these states and the rules to
1143	transition between them will be described in more detail - and while these
1144	rules might look complicated, they usually do "the right thing".
1145
1146	=over 4
1147
1148	=item initialiased
1149
1150	Before a watcher can be registered with the event looop it has to be
1151	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
1152	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
1153
1154	In this state it is simply some block of memory that is suitable for use
1155	in an event loop. It can be moved around, freed, reused etc. at will.
1156
1157	=item started/running/active
1158
1159	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
1160	property of the event loop, and is actively waiting for events. While in
1161	this state it cannot be accessed (except in a few documented ways), moved,
1162	freed or anything else - the only legal thing is to keep a pointer to it,
1163	and call libev functions on it that are documented to work on active watchers.
1164
1165	=item pending
1166
1167	If a watcher is active and libev determines that an event it is interested
1168	in has occurred (such as a timer expiring), it will become pending. It will
1169	stay in this pending state until either it is stopped or its callback is
1170	about to be invoked, so it is not normally pending inside the watcher
1171	callback.
1172
1173	The watcher might or might not be active while it is pending (for example,
1174	an expired non-repeating timer can be pending but no longer active). If it
1175	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
1176	but it is still property of the event loop at this time, so cannot be
1177	moved, freed or reused. And if it is active the rules described in the
1178	previous item still apply.
1179
1180	It is also possible to feed an event on a watcher that is not active (e.g.
1181	via C<ev_feed_event>), in which case it becomes pending without being
1182	active.
1183
1184	=item stopped
1185
1186	A watcher can be stopped implicitly by libev (in which case it might still
1187	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
1188	latter will clear any pending state the watcher might be in, regardless
1189	of whether it was active or not, so stopping a watcher explicitly before
1190	freeing it is often a good idea.
1191
1192	While stopped (and not pending) the watcher is essentially in the
1193	initialised state, that is it can be reused, moved, modified in any way
1194	you wish.
1195
1196	=back
1197
1198	=head2 GENERIC WATCHER FUNCTIONS	1209	=head2 GENERIC WATCHER FUNCTIONS
1199		1210
1200	=over 4	1211	=over 4
1201		1212
1202	=item C<ev_init> (ev_TYPE *watcher, callback)	1213	=item C<ev_init> (ev_TYPE *watcher, callback)
…		…
1343		1354
1344	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1355	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1345	functions that do not need a watcher.	1356	functions that do not need a watcher.
1346		1357
1347	=back	1358	=back
1348
1349		1359
1350	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1360	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1351		1361
1352	Each watcher has, by default, a member C<void *data> that you can change	1362	Each watcher has, by default, a member C<void *data> that you can change
1353	and read at any time: libev will completely ignore it. This can be used	1363	and read at any time: libev will completely ignore it. This can be used
…		…
1409	t2_cb (EV_P_ ev_timer *w, int revents)	1419	t2_cb (EV_P_ ev_timer *w, int revents)
1410	{	1420	{
1411	struct my_biggy big = (struct my_biggy *)	1421	struct my_biggy big = (struct my_biggy *)
1412	(((char *)w) - offsetof (struct my_biggy, t2));	1422	(((char *)w) - offsetof (struct my_biggy, t2));
1413	}	1423	}
		1424
		1425	=head2 WATCHER STATES
		1426
		1427	There are various watcher states mentioned throughout this manual -
		1428	active, pending and so on. In this section these states and the rules to
		1429	transition between them will be described in more detail - and while these
		1430	rules might look complicated, they usually do "the right thing".
		1431
		1432	=over 4
		1433
		1434	=item initialiased
		1435
		1436	Before a watcher can be registered with the event looop it has to be
		1437	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1438	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1439
		1440	In this state it is simply some block of memory that is suitable for use
		1441	in an event loop. It can be moved around, freed, reused etc. at will.
		1442
		1443	=item started/running/active
		1444
		1445	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1446	property of the event loop, and is actively waiting for events. While in
		1447	this state it cannot be accessed (except in a few documented ways), moved,
		1448	freed or anything else - the only legal thing is to keep a pointer to it,
		1449	and call libev functions on it that are documented to work on active watchers.
		1450
		1451	=item pending
		1452
		1453	If a watcher is active and libev determines that an event it is interested
		1454	in has occurred (such as a timer expiring), it will become pending. It will
		1455	stay in this pending state until either it is stopped or its callback is
		1456	about to be invoked, so it is not normally pending inside the watcher
		1457	callback.
		1458
		1459	The watcher might or might not be active while it is pending (for example,
		1460	an expired non-repeating timer can be pending but no longer active). If it
		1461	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1462	but it is still property of the event loop at this time, so cannot be
		1463	moved, freed or reused. And if it is active the rules described in the
		1464	previous item still apply.
		1465
		1466	It is also possible to feed an event on a watcher that is not active (e.g.
		1467	via C<ev_feed_event>), in which case it becomes pending without being
		1468	active.
		1469
		1470	=item stopped
		1471
		1472	A watcher can be stopped implicitly by libev (in which case it might still
		1473	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1474	latter will clear any pending state the watcher might be in, regardless
		1475	of whether it was active or not, so stopping a watcher explicitly before
		1476	freeing it is often a good idea.
		1477
		1478	While stopped (and not pending) the watcher is essentially in the
		1479	initialised state, that is it can be reused, moved, modified in any way
		1480	you wish.
		1481
		1482	=back
1414		1483
1415	=head2 WATCHER PRIORITY MODELS	1484	=head2 WATCHER PRIORITY MODELS
1416		1485
1417	Many event loops support I<watcher priorities>, which are usually small	1486	Many event loops support I<watcher priorities>, which are usually small
1418	integers that influence the ordering of event callback invocation	1487	integers that influence the ordering of event callback invocation
…		…
2237		2306
2238	=head2 C<ev_signal> - signal me when a signal gets signalled!	2307	=head2 C<ev_signal> - signal me when a signal gets signalled!
2239		2308
2240	Signal watchers will trigger an event when the process receives a specific	2309	Signal watchers will trigger an event when the process receives a specific
2241	signal one or more times. Even though signals are very asynchronous, libev	2310	signal one or more times. Even though signals are very asynchronous, libev
2242	will try it's best to deliver signals synchronously, i.e. as part of the	2311	will try its best to deliver signals synchronously, i.e. as part of the
2243	normal event processing, like any other event.	2312	normal event processing, like any other event.
2244		2313
2245	If you want signals to be delivered truly asynchronously, just use	2314	If you want signals to be delivered truly asynchronously, just use
2246	C<sigaction> as you would do without libev and forget about sharing	2315	C<sigaction> as you would do without libev and forget about sharing
2247	the signal. You can even use C<ev_async> from a signal handler to	2316	the signal. You can even use C<ev_async> from a signal handler to
…		…
2289	I<has> to modify the signal mask, at least temporarily.	2358	I<has> to modify the signal mask, at least temporarily.
2290		2359
2291	So I can't stress this enough: I<If you do not reset your signal mask when	2360	So I can't stress this enough: I<If you do not reset your signal mask when
2292	you expect it to be empty, you have a race condition in your code>. This	2361	you expect it to be empty, you have a race condition in your code>. This
2293	is not a libev-specific thing, this is true for most event libraries.	2362	is not a libev-specific thing, this is true for most event libraries.
		2363
		2364	=head3 The special problem of threads signal handling
		2365
		2366	POSIX threads has problematic signal handling semantics, specifically,
		2367	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2368	threads in a process block signals, which is hard to achieve.
		2369
		2370	When you want to use sigwait (or mix libev signal handling with your own
		2371	for the same signals), you can tackle this problem by globally blocking
		2372	all signals before creating any threads (or creating them with a fully set
		2373	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2374	loops. Then designate one thread as "signal receiver thread" which handles
		2375	these signals. You can pass on any signals that libev might be interested
		2376	in by calling C<ev_feed_signal>.
2294		2377
2295	=head3 Watcher-Specific Functions and Data Members	2378	=head3 Watcher-Specific Functions and Data Members
2296		2379
2297	=over 4	2380	=over 4
2298		2381
…		…
3072	disadvantage of having to use multiple event loops (which do not support	3155	disadvantage of having to use multiple event loops (which do not support
3073	signal watchers).	3156	signal watchers).
3074		3157
3075	When this is not possible, or you want to use the default loop for	3158	When this is not possible, or you want to use the default loop for
3076	other reasons, then in the process that wants to start "fresh", call	3159	other reasons, then in the process that wants to start "fresh", call
3077	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3160	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
3078	the default loop will "orphan" (not stop) all registered watchers, so you	3161	Destroying the default loop will "orphan" (not stop) all registered
3079	have to be careful not to execute code that modifies those watchers. Note	3162	watchers, so you have to be careful not to execute code that modifies
3080	also that in that case, you have to re-register any signal watchers.	3163	those watchers. Note also that in that case, you have to re-register any
		3164	signal watchers.
3081		3165
3082	=head3 Watcher-Specific Functions and Data Members	3166	=head3 Watcher-Specific Functions and Data Members
3083		3167
3084	=over 4	3168	=over 4
3085		3169
3086	=item ev_fork_init (ev_signal *, callback)	3170	=item ev_fork_init (ev_fork *, callback)
3087		3171
3088	Initialises and configures the fork watcher - it has no parameters of any	3172	Initialises and configures the fork watcher - it has no parameters of any
3089	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3173	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3090	believe me.	3174	really.
3091		3175
3092	=back	3176	=back
		3177
		3178
		3179	=head2 C<ev_cleanup> - even the best things end
		3180
		3181	Cleanup watchers are called just before the event loop is being destroyed
		3182	by a call to C<ev_loop_destroy>.
		3183
		3184	While there is no guarantee that the event loop gets destroyed, cleanup
		3185	watchers provide a convenient method to install cleanup hooks for your
		3186	program, worker threads and so on - you just to make sure to destroy the
		3187	loop when you want them to be invoked.
		3188
		3189	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3190	all other watchers, they do not keep a reference to the event loop (which
		3191	makes a lot of sense if you think about it). Like all other watchers, you
		3192	can call libev functions in the callback, except C<ev_cleanup_start>.
		3193
		3194	=head3 Watcher-Specific Functions and Data Members
		3195
		3196	=over 4
		3197
		3198	=item ev_cleanup_init (ev_cleanup *, callback)
		3199
		3200	Initialises and configures the cleanup watcher - it has no parameters of
		3201	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3202	pointless, I assure you.
		3203
		3204	=back
		3205
		3206	Example: Register an atexit handler to destroy the default loop, so any
		3207	cleanup functions are called.
		3208
		3209	static void
		3210	program_exits (void)
		3211	{
		3212	ev_loop_destroy (EV_DEFAULT_UC);
		3213	}
		3214
		3215	...
		3216	atexit (program_exits);
3093		3217
3094		3218
3095	=head2 C<ev_async> - how to wake up an event loop	3219	=head2 C<ev_async> - how to wake up an event loop
3096		3220
3097	In general, you cannot use an C<ev_run> from multiple threads or other	3221	In general, you cannot use an C<ev_run> from multiple threads or other
…		…
3104	it by calling C<ev_async_send>, which is thread- and signal safe.	3228	it by calling C<ev_async_send>, which is thread- and signal safe.
3105		3229
3106	This functionality is very similar to C<ev_signal> watchers, as signals,	3230	This functionality is very similar to C<ev_signal> watchers, as signals,
3107	too, are asynchronous in nature, and signals, too, will be compressed	3231	too, are asynchronous in nature, and signals, too, will be compressed
3108	(i.e. the number of callback invocations may be less than the number of	3232	(i.e. the number of callback invocations may be less than the number of
3109	C<ev_async_sent> calls).	3233	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3234	of "global async watchers" by using a watcher on an otherwise unused
		3235	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3236	even without knowing which loop owns the signal.
3110		3237
3111	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3238	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
3112	just the default loop.	3239	just the default loop.
3113		3240
3114	=head3 Queueing	3241	=head3 Queueing
…		…
3290	Feed an event on the given fd, as if a file descriptor backend detected	3417	Feed an event on the given fd, as if a file descriptor backend detected
3291	the given events it.	3418	the given events it.
3292		3419
3293	=item ev_feed_signal_event (loop, int signum)	3420	=item ev_feed_signal_event (loop, int signum)
3294		3421
3295	Feed an event as if the given signal occurred (C<loop> must be the default	3422	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3296	loop!).	3423	which is async-safe.
		3424
		3425	=back
		3426
		3427
		3428	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3429
		3430	This section explains some common idioms that are not immediately
		3431	obvious. Note that examples are sprinkled over the whole manual, and this
		3432	section only contains stuff that wouldn't fit anywhere else.
		3433
		3434	=over 4
		3435
		3436	=item Model/nested event loop invocations and exit conditions.
		3437
		3438	Often (especially in GUI toolkits) there are places where you have
		3439	I<modal> interaction, which is most easily implemented by recursively
		3440	invoking C<ev_run>.
		3441
		3442	This brings the problem of exiting - a callback might want to finish the
		3443	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3444	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3445	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3446	other combination: In these cases, C<ev_break> will not work alone.
		3447
		3448	The solution is to maintain "break this loop" variable for each C<ev_run>
		3449	invocation, and use a loop around C<ev_run> until the condition is
		3450	triggered, using C<EVRUN_ONCE>:
		3451
		3452	// main loop
		3453	int exit_main_loop = 0;
		3454
		3455	while (!exit_main_loop)
		3456	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3457
		3458	// in a model watcher
		3459	int exit_nested_loop = 0;
		3460
		3461	while (!exit_nested_loop)
		3462	ev_run (EV_A_ EVRUN_ONCE);
		3463
		3464	To exit from any of these loops, just set the corresponding exit variable:
		3465
		3466	// exit modal loop
		3467	exit_nested_loop = 1;
		3468
		3469	// exit main program, after modal loop is finished
		3470	exit_main_loop = 1;
		3471
		3472	// exit both
		3473	exit_main_loop = exit_nested_loop = 1;
3297		3474
3298	=back	3475	=back
3299		3476
3300		3477
3301	=head1 LIBEVENT EMULATION	3478	=head1 LIBEVENT EMULATION
3302		3479
3303	Libev offers a compatibility emulation layer for libevent. It cannot	3480	Libev offers a compatibility emulation layer for libevent. It cannot
3304	emulate the internals of libevent, so here are some usage hints:	3481	emulate the internals of libevent, so here are some usage hints:
3305		3482
3306	=over 4	3483	=over 4
		3484
		3485	=item * Only the libevent-1.4.1-beta API is being emulated.
		3486
		3487	This was the newest libevent version available when libev was implemented,
		3488	and is still mostly unchanged in 2010.
3307		3489
3308	=item * Use it by including <event.h>, as usual.	3490	=item * Use it by including <event.h>, as usual.
3309		3491
3310	=item * The following members are fully supported: ev_base, ev_callback,	3492	=item * The following members are fully supported: ev_base, ev_callback,
3311	ev_arg, ev_fd, ev_res, ev_events.	3493	ev_arg, ev_fd, ev_res, ev_events.
…		…
3317	=item * Priorities are not currently supported. Initialising priorities	3499	=item * Priorities are not currently supported. Initialising priorities
3318	will fail and all watchers will have the same priority, even though there	3500	will fail and all watchers will have the same priority, even though there
3319	is an ev_pri field.	3501	is an ev_pri field.
3320		3502
3321	=item * In libevent, the last base created gets the signals, in libev, the	3503	=item * In libevent, the last base created gets the signals, in libev, the
3322	first base created (== the default loop) gets the signals.	3504	base that registered the signal gets the signals.
3323		3505
3324	=item * Other members are not supported.	3506	=item * Other members are not supported.
3325		3507
3326	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3508	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3327	to use the libev header file and library.	3509	to use the libev header file and library.
…		…
3346	Care has been taken to keep the overhead low. The only data member the C++	3528	Care has been taken to keep the overhead low. The only data member the C++
3347	classes add (compared to plain C-style watchers) is the event loop pointer	3529	classes add (compared to plain C-style watchers) is the event loop pointer
3348	that the watcher is associated with (or no additional members at all if	3530	that the watcher is associated with (or no additional members at all if
3349	you disable C<EV_MULTIPLICITY> when embedding libev).	3531	you disable C<EV_MULTIPLICITY> when embedding libev).
3350		3532
3351	Currently, functions, and static and non-static member functions can be	3533	Currently, functions, static and non-static member functions and classes
3352	used as callbacks. Other types should be easy to add as long as they only	3534	with C<operator ()> can be used as callbacks. Other types should be easy
3353	need one additional pointer for context. If you need support for other	3535	to add as long as they only need one additional pointer for context. If
3354	types of functors please contact the author (preferably after implementing	3536	you need support for other types of functors please contact the author
3355	it).	3537	(preferably after implementing it).
3356		3538
3357	Here is a list of things available in the C<ev> namespace:	3539	Here is a list of things available in the C<ev> namespace:
3358		3540
3359	=over 4	3541	=over 4
3360		3542
…		…
4531	=head3 C<kqueue> is buggy	4713	=head3 C<kqueue> is buggy
4532		4714
4533	The kqueue syscall is broken in all known versions - most versions support	4715	The kqueue syscall is broken in all known versions - most versions support
4534	only sockets, many support pipes.	4716	only sockets, many support pipes.
4535		4717
4536	Libev tries to work around this by not using C<kqueue> by default on	4718	Libev tries to work around this by not using C<kqueue> by default on this
4537	this rotten platform, but of course you can still ask for it when creating	4719	rotten platform, but of course you can still ask for it when creating a
4538	a loop.	4720	loop - embedding a socket-only kqueue loop into a select-based one is
		4721	probably going to work well.
4539		4722
4540	=head3 C<poll> is buggy	4723	=head3 C<poll> is buggy
4541		4724
4542	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>	4725	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
4543	implementation by something calling C<kqueue> internally around the 10.5.6	4726	implementation by something calling C<kqueue> internally around the 10.5.6
…		…
4562		4745
4563	=head3 C<errno> reentrancy	4746	=head3 C<errno> reentrancy
4564		4747
4565	The default compile environment on Solaris is unfortunately so	4748	The default compile environment on Solaris is unfortunately so
4566	thread-unsafe that you can't even use components/libraries compiled	4749	thread-unsafe that you can't even use components/libraries compiled
4567	without C<-D_REENTRANT> (as long as they use C<errno>), which, of course,	4750	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
4568	isn't defined by default.	4751	defined by default. A valid, if stupid, implementation choice.
4569		4752
4570	If you want to use libev in threaded environments you have to make sure	4753	If you want to use libev in threaded environments you have to make sure
4571	it's compiled with C<_REENTRANT> defined.	4754	it's compiled with C<_REENTRANT> defined.
4572		4755
4573	=head3 Event port backend	4756	=head3 Event port backend
4574		4757
4575	The scalable event interface for Solaris is called "event ports". Unfortunately,	4758	The scalable event interface for Solaris is called "event
4576	this mechanism is very buggy. If you run into high CPU usage, your program	4759	ports". Unfortunately, this mechanism is very buggy in all major
		4760	releases. If you run into high CPU usage, your program freezes or you get
4577	freezes or you get a large number of spurious wakeups, make sure you have	4761	a large number of spurious wakeups, make sure you have all the relevant
4578	all the relevant and latest kernel patches applied. No, I don't know which	4762	and latest kernel patches applied. No, I don't know which ones, but there
4579	ones, but there are multiple ones.	4763	are multiple ones to apply, and afterwards, event ports actually work
		4764	great.
4580		4765
4581	If you can't get it to work, you can try running the program by setting	4766	If you can't get it to work, you can try running the program by setting
4582	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and	4767	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
4583	C<select> backends.	4768	C<select> backends.
4584		4769
4585	=head2 AIX POLL BUG	4770	=head2 AIX POLL BUG
4586		4771
4587	AIX unfortunately has a broken C<poll.h> header. Libev works around	4772	AIX unfortunately has a broken C<poll.h> header. Libev works around
4588	this by trying to avoid the poll backend altogether (i.e. it's not even	4773	this by trying to avoid the poll backend altogether (i.e. it's not even
4589	compiled in), which normally isn't a big problem as C<select> works fine	4774	compiled in), which normally isn't a big problem as C<select> works fine
4590	with large bitsets, and AIX is dead anyway.	4775	with large bitsets on AIX, and AIX is dead anyway.
4591		4776
4592	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4777	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
4593		4778
4594	=head3 General issues	4779	=head3 General issues
4595		4780
…		…
4701	structure (guaranteed by POSIX but not by ISO C for example), but it also	4886	structure (guaranteed by POSIX but not by ISO C for example), but it also
4702	assumes that the same (machine) code can be used to call any watcher	4887	assumes that the same (machine) code can be used to call any watcher
4703	callback: The watcher callbacks have different type signatures, but libev	4888	callback: The watcher callbacks have different type signatures, but libev
4704	calls them using an C<ev_watcher *> internally.	4889	calls them using an C<ev_watcher *> internally.
4705		4890
		4891	=item pointer accesses must be thread-atomic
		4892
		4893	Accessing a pointer value must be atomic, it must both be readable and
		4894	writable in one piece - this is the case on all current architectures.
		4895
4706	=item C<sig_atomic_t volatile> must be thread-atomic as well	4896	=item C<sig_atomic_t volatile> must be thread-atomic as well
4707		4897
4708	The type C<sig_atomic_t volatile> (or whatever is defined as	4898	The type C<sig_atomic_t volatile> (or whatever is defined as
4709	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4899	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
4710	threads. This is not part of the specification for C<sig_atomic_t>, but is	4900	threads. This is not part of the specification for C<sig_atomic_t>, but is
…		…
4816	=back	5006	=back
4817		5007
4818		5008
4819	=head1 PORTING FROM LIBEV 3.X TO 4.X	5009	=head1 PORTING FROM LIBEV 3.X TO 4.X
4820		5010
4821	The major version 4 introduced some minor incompatible changes to the API.	5011	The major version 4 introduced some incompatible changes to the API.
4822		5012
4823	At the moment, the C<ev.h> header file tries to implement superficial	5013	At the moment, the C<ev.h> header file provides compatibility definitions
4824	compatibility, so most programs should still compile. Those might be	5014	for all changes, so most programs should still compile. The compatibility
4825	removed in later versions of libev, so better update early than late.	5015	layer might be removed in later versions of libev, so better update to the
		5016	new API early than late.
4826		5017
4827	=over 4	5018	=over 4
		5019
		5020	=item C<EV_COMPAT3> backwards compatibility mechanism
		5021
		5022	The backward compatibility mechanism can be controlled by
		5023	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5024	section.
		5025
		5026	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5027
		5028	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5029
		5030	ev_loop_destroy (EV_DEFAULT_UC);
		5031	ev_loop_fork (EV_DEFAULT);
4828		5032
4829	=item function/symbol renames	5033	=item function/symbol renames
4830		5034
4831	A number of functions and symbols have been renamed:	5035	A number of functions and symbols have been renamed:
4832		5036
…		…
4851	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme	5055	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
4852	as all other watcher types. Note that C<ev_loop_fork> is still called	5056	as all other watcher types. Note that C<ev_loop_fork> is still called
4853	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>	5057	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4854	typedef.	5058	typedef.
4855		5059
4856	=item C<EV_COMPAT3> backwards compatibility mechanism
4857
4858	The backward compatibility mechanism can be controlled by
4859	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
4860	section.
4861
4862	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	5060	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4863		5061
4864	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	5062	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4865	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	5063	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
4866	and work, but the library code will of course be larger.	5064	and work, but the library code will of course be larger.
…		…
4872		5070
4873	=over 4	5071	=over 4
4874		5072
4875	=item active	5073	=item active
4876		5074
4877	A watcher is active as long as it has been started (has been attached to	5075	A watcher is active as long as it has been started and not yet stopped.
4878	an event loop) but not yet stopped (disassociated from the event loop).	5076	See L<WATCHER STATES> for details.
4879		5077
4880	=item application	5078	=item application
4881		5079
4882	In this document, an application is whatever is using libev.	5080	In this document, an application is whatever is using libev.
		5081
		5082	=item backend
		5083
		5084	The part of the code dealing with the operating system interfaces.
4883		5085
4884	=item callback	5086	=item callback
4885		5087
4886	The address of a function that is called when some event has been	5088	The address of a function that is called when some event has been
4887	detected. Callbacks are being passed the event loop, the watcher that	5089	detected. Callbacks are being passed the event loop, the watcher that
4888	received the event, and the actual event bitset.	5090	received the event, and the actual event bitset.
4889		5091
4890	=item callback invocation	5092	=item callback/watcher invocation
4891		5093
4892	The act of calling the callback associated with a watcher.	5094	The act of calling the callback associated with a watcher.
4893		5095
4894	=item event	5096	=item event
4895		5097
…		…
4914	The model used to describe how an event loop handles and processes	5116	The model used to describe how an event loop handles and processes
4915	watchers and events.	5117	watchers and events.
4916		5118
4917	=item pending	5119	=item pending
4918		5120
4919	A watcher is pending as soon as the corresponding event has been detected,	5121	A watcher is pending as soon as the corresponding event has been
4920	and stops being pending as soon as the watcher will be invoked or its	5122	detected. See L<WATCHER STATES> for details.
4921	pending status is explicitly cleared by the application.
4922
4923	A watcher can be pending, but not active. Stopping a watcher also clears
4924	its pending status.
4925		5123
4926	=item real time	5124	=item real time
4927		5125
4928	The physical time that is observed. It is apparently strictly monotonic :)	5126	The physical time that is observed. It is apparently strictly monotonic :)
4929		5127
…		…
4936	=item watcher	5134	=item watcher
4937		5135
4938	A data structure that describes interest in certain events. Watchers need	5136	A data structure that describes interest in certain events. Watchers need
4939	to be started (attached to an event loop) before they can receive events.	5137	to be started (attached to an event loop) before they can receive events.
4940		5138
4941	=item watcher invocation
4942
4943	The act of calling the callback associated with a watcher.
4944
4945	=back	5139	=back
4946		5140
4947	=head1 AUTHOR	5141	=head1 AUTHOR
4948		5142
4949	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5143	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5144	Magnusson and Emanuele Giaquinta.
4950		5145

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Comparing libev/ev.pod (file contents): Revision 1.313 by root, Fri Oct 22 05:44:33 2010 UTC vs. Revision 1.352 by root, Mon Jan 10 14:30:15 2011 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.313 by root, Fri Oct 22 05:44:33 2010 UTC vs.
Revision 1.352 by root, Mon Jan 10 14:30:15 2011 UTC