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

Comparing libev/ev.pod (file contents):
Revision 1.319 by root, Fri Oct 22 10:09:12 2010 UTC vs.
Revision 1.351 by root, Mon Jan 10 14:24:26 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
…		…
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. Also interetsing is the combination of	178	you actually want to know. Also interesting is the combination of
171	C<ev_update_now> and C<ev_now>.	179	C<ev_update_now> and C<ev_now>.
172		180
173	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
174		182
175	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
…		…
193	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
194	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
195	not a problem.	203	not a problem.
196		204
197	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
198	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).
199		208
200	assert (("libev version mismatch",	209	assert (("libev version mismatch",
201	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
202	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
203		212
…		…
232	the current system, you would need to look at C<ev_embeddable_backends ()	241	the current system, you would need to look at C<ev_embeddable_backends ()
233	& ev_supported_backends ()>, likewise for recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
234		243
235	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
236		245
237	=item ev_set_allocator (void (cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void (cb)(void *ptr, long size))
238		247
239	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
240	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
241	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
242	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
…		…
268	}	277	}
269		278
270	...	279	...
271	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
272		281
273	=item ev_set_syserr_cb (void (cb)(const char msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (cb)(const char msg))
274		283
275	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
276	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
277	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
278	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
…		…
290	}	299	}
291		300
292	...	301	...
293	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
294		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
295	=back	317	=back
296		318
297	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	319	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
298		320
299	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
300	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
301	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).
302		324
303	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
304	supports signals and child events, and dynamically created event loops	326	supports child process events, and dynamically created event loops which
305	which do not.	327	do not.
306		328
307	=over 4	329	=over 4
308		330
309	=item struct ev_loop *ev_default_loop (unsigned int flags)	331	=item struct ev_loop *ev_default_loop (unsigned int flags)
310		332
311	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
312	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
313	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
314	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".
315		343
316	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
317	function.	345	function (or via the C<EV_DEFAULT> macro).
318		346
319	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
320	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
321	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).
322		351
323	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,
324	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
325	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
326	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
327	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	356	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
328	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.
329		376
330	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
331	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>).
332		379
333	The following flags are supported:	380	The following flags are supported:
…		…
368	environment variable.	415	environment variable.
369		416
370	=item C<EVFLAG_NOINOTIFY>	417	=item C<EVFLAG_NOINOTIFY>
371		418
372	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
373	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
374	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
375	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.
376		423
377	=item C<EVFLAG_SIGNALFD>	424	=item C<EVFLAG_SIGNALFD>
378		425
379	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
380	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
381	delivers signals synchronously, which makes it both faster and might make	428	delivers signals synchronously, which makes it both faster and might make
382	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
383	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
384	threads that are not interested in handling them.	431	threads that are not interested in handling them.
385		432
386	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
387	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
388	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.
389		448
390	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
391		450
392	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
393	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,
…		…
429	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
430		489
431	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
432	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
433	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
434	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
435	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
436	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
437	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
438	hard to detect.	499	and is of course hard to detect.
439		500
440	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
441	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
442	I<different> file descriptors (even already closed ones, so one cannot	503	I<different> file descriptors (even already closed ones, so one cannot
443	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
…		…
445	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
446	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
447	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
448	perfectly fine with C<select> (files, many character devices...).	509	perfectly fine with C<select> (files, many character devices...).
449		510
		511	Epoll is truly the train wreck analog among event poll mechanisms.
		512
450	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
451	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
452	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
453	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
454	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
…		…
519	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	582	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
520		583
521	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,
522	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)).
523		586
524	Please note that Solaris event ports can deliver a lot of spurious
525	notifications, so you need to use non-blocking I/O or other means to avoid
526	blocking when no data (or space) is available.
527
528	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
529	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
530	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	589	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
531	might perform better.	590	might perform better.
532		591
533	On the positive side, with the exception of the spurious readiness	592	On the positive side, this backend actually performed fully to
534	notifications, this backend actually performed fully to specification
535	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
536	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.
537		602
538	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
539	C<EVBACKEND_POLL>.	604	C<EVBACKEND_POLL>.
540		605
541	=item C<EVBACKEND_ALL>	606	=item C<EVBACKEND_ALL>
542		607
543	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
544	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
545	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	610	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
546		611
547	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).
548		621
549	=back	622	=back
550		623
551	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,
552	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
553	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
554	()> will be tried.	627	()> will be tried.
555		628
556	Example: This is the most typical usage.
557
558	if (!ev_default_loop (0))
559	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
560
561	Example: Restrict libev to the select and poll backends, and do not allow
562	environment settings to be taken into account:
563
564	ev_default_loop (EVBACKEND_POLL \| EVBACKEND_SELECT \| EVFLAG_NOENV);
565
566	Example: Use whatever libev has to offer, but make sure that kqueue is
567	used if available (warning, breaks stuff, best use only with your own
568	private event loop and only if you know the OS supports your types of
569	fds):
570
571	ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);
572
573	=item struct ev_loop *ev_loop_new (unsigned int flags)
574
575	Similar to C<ev_default_loop>, but always creates a new event loop that is
576	always distinct from the default loop.
577
578	Note that this function I<is> thread-safe, and one common way to use
579	libev with threads is indeed to create one loop per thread, and using the
580	default loop in the "main" or "initial" thread.
581
582	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.
583		630
584	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	631	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
585	if (!epoller)	632	if (!epoller)
586	fatal ("no epoll found here, maybe it hides under your chair");	633	fatal ("no epoll found here, maybe it hides under your chair");
587		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
588	=item ev_default_destroy ()	640	=item ev_loop_destroy (loop)
589		641
590	Destroys the default loop (frees all memory and kernel state etc.). None	642	Destroys an event loop object (frees all memory and kernel state
591	of the active event watchers will be stopped in the normal sense, so	643	etc.). None of the active event watchers will be stopped in the normal
592	e.g. C<ev_is_active> might still return true. It is your responsibility to	644	sense, so e.g. C<ev_is_active> might still return true. It is your
593	either stop all watchers cleanly yourself I<before> calling this function,	645	responsibility to either stop all watchers cleanly yourself I<before>
594	or cope with the fact afterwards (which is usually the easiest thing, you	646	calling this function, or cope with the fact afterwards (which is usually
595	can just ignore the watchers and/or C<free ()> them for example).	647	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		648	for example).
596		649
597	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
598	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
599	as signal and child watchers) would need to be stopped manually.	652	as signal and child watchers) would need to be stopped manually.
600		653
601	In general it is not advisable to call this function except in the	654	This function is normally used on loop objects allocated by
602	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.
603	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>
604	C<ev_loop_new> and C<ev_loop_destroy>.	661	and C<ev_loop_destroy>.
605		662
606	=item ev_loop_destroy (loop)	663	=item ev_loop_fork (loop)
607		664
608	Like C<ev_default_destroy>, but destroys an event loop created by an
609	earlier call to C<ev_loop_new>.
610
611	=item ev_default_fork ()
612
613	This function sets a flag that causes subsequent C<ev_run> iterations	665	This function sets a flag that causes subsequent C<ev_run> iterations to
614	to reinitialise the kernel state for backends that have one. Despite the	666	reinitialise the kernel state for backends that have one. Despite the
615	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
616	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
617	sense). You I<must> call it in the child before using any of the libev	669	child before resuming or calling C<ev_run>.
618	functions, and it will only take effect at the next C<ev_run> iteration.
619		670
620	Again, you I<have> to call it on I<any> loop that you want to re-use after	671	Again, you I<have> to call it on I<any> loop that you want to re-use after
621	a fork, I<even if you do not plan to use the loop in the parent>. This is	672	a fork, I<even if you do not plan to use the loop in the parent>. This is
622	because some kernel interfaces cough I<kqueue> cough do funny things	673	because some kernel interfaces cough I<kqueue> cough do funny things
623	during fork.	674	during fork.
…		…
628	call it at all (in fact, C<epoll> is so badly broken that it makes a	679	call it at all (in fact, C<epoll> is so badly broken that it makes a
629	difference, but libev will usually detect this case on its own and do a	680	difference, but libev will usually detect this case on its own and do a
630	costly reset of the backend).	681	costly reset of the backend).
631		682
632	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
633	it just in case after a fork. To make this easy, the function will fit in	684	it just in case after a fork.
634	quite nicely into a call to C<pthread_atfork>:
635		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	...
636	pthread_atfork (0, 0, ev_default_fork);	696	pthread_atfork (0, 0, post_fork_child);
637
638	=item ev_loop_fork (loop)
639
640	Like C<ev_default_fork>, but acts on an event loop created by
641	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
642	after fork that you want to re-use in the child, and how you keep track of
643	them is entirely your own problem.
644		697
645	=item int ev_is_default_loop (loop)	698	=item int ev_is_default_loop (loop)
646		699
647	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
648	otherwise.	701	otherwise.
…		…
659	prepare and check phases.	712	prepare and check phases.
660		713
661	=item unsigned int ev_depth (loop)	714	=item unsigned int ev_depth (loop)
662		715
663	Returns the number of times C<ev_run> was entered minus the number of	716	Returns the number of times C<ev_run> was entered minus the number of
664	times C<ev_run> was exited, in other words, the recursion depth.	717	times C<ev_run> was exited normally, in other words, the recursion depth.
665		718
666	Outside C<ev_run>, 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
667	C<1>, unless C<ev_run> was invoked recursively (or from another thread),	720	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
668	in which case it is higher.	721	in which case it is higher.
669		722
670	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread	723	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
671	etc.), doesn't count as "exit" - consider this as a hint to avoid such	724	throwing an exception etc.), doesn't count as "exit" - consider this
672	ungentleman-like behaviour unless it's really convenient.	725	as a hint to avoid such ungentleman-like behaviour unless it's really
		726	convenient, in which case it is fully supported.
673		727
674	=item unsigned int ev_backend (loop)	728	=item unsigned int ev_backend (loop)
675		729
676	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
677	use.	731	use.
…		…
738	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
739	finished (especially in interactive programs), but having a program	793	finished (especially in interactive programs), but having a program
740	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
741	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
742	beauty.	796	beauty.
		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.
743		802
744	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle	803	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
745	those events and any already outstanding ones, but will not wait and	804	those events and any already outstanding ones, but will not wait and
746	block your process in case there are no events and will return after one	805	block your process in case there are no events and will return after one
747	iteration of the loop. This is sometimes useful to poll and handle new	806	iteration of the loop. This is sometimes useful to poll and handle new
…		…
809	Can be used to make a call to C<ev_run> return early (but only after it	868	Can be used to make a call to C<ev_run> return early (but only after it
810	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
811	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or	870	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
812	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.	871	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
813		872
814	This "unloop state" will be cleared when entering C<ev_run> again.	873	This "break state" will be cleared on the next call to C<ev_run>.
815		874
816	It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO##	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.
817		877
818	=item ev_ref (loop)	878	=item ev_ref (loop)
819		879
820	=item ev_unref (loop)	880	=item ev_unref (loop)
821		881
…		…
842	running when nothing else is active.	902	running when nothing else is active.
843		903
844	ev_signal exitsig;	904	ev_signal exitsig;
845	ev_signal_init (&exitsig, sig_cb, SIGINT);	905	ev_signal_init (&exitsig, sig_cb, SIGINT);
846	ev_signal_start (loop, &exitsig);	906	ev_signal_start (loop, &exitsig);
847	evf_unref (loop);	907	ev_unref (loop);
848		908
849	Example: For some weird reason, unregister the above signal handler again.	909	Example: For some weird reason, unregister the above signal handler again.
850		910
851	ev_ref (loop);	911	ev_ref (loop);
852	ev_signal_stop (loop, &exitsig);	912	ev_signal_stop (loop, &exitsig);
…		…
964	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
965	document.	1025	document.
966		1026
967	=item ev_set_userdata (loop, void *data)	1027	=item ev_set_userdata (loop, void *data)
968		1028
969	=item ev_userdata (loop)	1029	=item void *ev_userdata (loop)
970		1030
971	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
972	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
973	C<0.>	1033	C<0>.
974		1034
975	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,
976	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
977	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
978	any other purpose as well.	1038	any other purpose as well.
…		…
1106	=item C<EV_FORK>	1166	=item C<EV_FORK>
1107		1167
1108	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
1109	C<ev_fork>).	1169	C<ev_fork>).
1110		1170
		1171	=item C<EV_CLEANUP>
		1172
		1173	The event loop is about to be destroyed (see C<ev_cleanup>).
		1174
1111	=item C<EV_ASYNC>	1175	=item C<EV_ASYNC>
1112		1176
1113	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>).
1114		1178
1115	=item C<EV_CUSTOM>	1179	=item C<EV_CUSTOM>
…		…
1136	programs, though, as the fd could already be closed and reused for another	1200	programs, though, as the fd could already be closed and reused for another
1137	thing, so beware.	1201	thing, so beware.
1138		1202
1139	=back	1203	=back
1140		1204
1141	=head2 WATCHER STATES
1142
1143	There are various watcher states mentioned throughout this manual -
1144	active, pending and so on. In this section these states and the rules to
1145	transition between them will be described in more detail - and while these
1146	rules might look complicated, they usually do "the right thing".
1147
1148	=over 4
1149
1150	=item initialiased
1151
1152	Before a watcher can be registered with the event looop it has to be
1153	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
1154	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
1155
1156	In this state it is simply some block of memory that is suitable for use
1157	in an event loop. It can be moved around, freed, reused etc. at will.
1158
1159	=item started/running/active
1160
1161	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
1162	property of the event loop, and is actively waiting for events. While in
1163	this state it cannot be accessed (except in a few documented ways), moved,
1164	freed or anything else - the only legal thing is to keep a pointer to it,
1165	and call libev functions on it that are documented to work on active watchers.
1166
1167	=item pending
1168
1169	If a watcher is active and libev determines that an event it is interested
1170	in has occurred (such as a timer expiring), it will become pending. It will
1171	stay in this pending state until either it is stopped or its callback is
1172	about to be invoked, so it is not normally pending inside the watcher
1173	callback.
1174
1175	The watcher might or might not be active while it is pending (for example,
1176	an expired non-repeating timer can be pending but no longer active). If it
1177	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
1178	but it is still property of the event loop at this time, so cannot be
1179	moved, freed or reused. And if it is active the rules described in the
1180	previous item still apply.
1181
1182	It is also possible to feed an event on a watcher that is not active (e.g.
1183	via C<ev_feed_event>), in which case it becomes pending without being
1184	active.
1185
1186	=item stopped
1187
1188	A watcher can be stopped implicitly by libev (in which case it might still
1189	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
1190	latter will clear any pending state the watcher might be in, regardless
1191	of whether it was active or not, so stopping a watcher explicitly before
1192	freeing it is often a good idea.
1193
1194	While stopped (and not pending) the watcher is essentially in the
1195	initialised state, that is it can be reused, moved, modified in any way
1196	you wish.
1197
1198	=back
1199
1200	=head2 GENERIC WATCHER FUNCTIONS	1205	=head2 GENERIC WATCHER FUNCTIONS
1201		1206
1202	=over 4	1207	=over 4
1203		1208
1204	=item C<ev_init> (ev_TYPE *watcher, callback)	1209	=item C<ev_init> (ev_TYPE *watcher, callback)
…		…
1345		1350
1346	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1351	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1347	functions that do not need a watcher.	1352	functions that do not need a watcher.
1348		1353
1349	=back	1354	=back
1350
1351		1355
1352	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1356	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1353		1357
1354	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
1355	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
…		…
1411	t2_cb (EV_P_ ev_timer *w, int revents)	1415	t2_cb (EV_P_ ev_timer *w, int revents)
1412	{	1416	{
1413	struct my_biggy big = (struct my_biggy *)	1417	struct my_biggy big = (struct my_biggy *)
1414	(((char *)w) - offsetof (struct my_biggy, t2));	1418	(((char *)w) - offsetof (struct my_biggy, t2));
1415	}	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
1416		1479
1417	=head2 WATCHER PRIORITY MODELS	1480	=head2 WATCHER PRIORITY MODELS
1418		1481
1419	Many event loops support I<watcher priorities>, which are usually small	1482	Many event loops support I<watcher priorities>, which are usually small
1420	integers that influence the ordering of event callback invocation	1483	integers that influence the ordering of event callback invocation
…		…
2239		2302
2240	=head2 C<ev_signal> - signal me when a signal gets signalled!	2303	=head2 C<ev_signal> - signal me when a signal gets signalled!
2241		2304
2242	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
2243	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
2244	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
2245	normal event processing, like any other event.	2308	normal event processing, like any other event.
2246		2309
2247	If you want signals to be delivered truly asynchronously, just use	2310	If you want signals to be delivered truly asynchronously, just use
2248	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
2249	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
…		…
2291	I<has> to modify the signal mask, at least temporarily.	2354	I<has> to modify the signal mask, at least temporarily.
2292		2355
2293	So I can't stress this enough: I<If you do not reset your signal mask when	2356	So I can't stress this enough: I<If you do not reset your signal mask when
2294	you expect it to be empty, you have a race condition in your code>. This	2357	you expect it to be empty, you have a race condition in your code>. This
2295	is not a libev-specific thing, this is true for most event libraries.	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>.
2296		2373
2297	=head3 Watcher-Specific Functions and Data Members	2374	=head3 Watcher-Specific Functions and Data Members
2298		2375
2299	=over 4	2376	=over 4
2300		2377
…		…
3074	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
3075	signal watchers).	3152	signal watchers).
3076		3153
3077	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
3078	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
3079	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3156	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
3080	the default loop will "orphan" (not stop) all registered watchers, so you	3157	Destroying the default loop will "orphan" (not stop) all registered
3081	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
3082	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.
3083		3161
3084	=head3 Watcher-Specific Functions and Data Members	3162	=head3 Watcher-Specific Functions and Data Members
3085		3163
3086	=over 4	3164	=over 4
3087		3165
3088	=item ev_fork_init (ev_signal *, callback)	3166	=item ev_fork_init (ev_fork *, callback)
3089		3167
3090	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
3091	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,
3092	believe me.	3170	really.
3093		3171
3094	=back	3172	=back
		3173
		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);
3095		3213
3096		3214
3097	=head2 C<ev_async> - how to wake up an event loop	3215	=head2 C<ev_async> - how to wake up an event loop
3098		3216
3099	In general, you cannot use an C<ev_run> from multiple threads or other	3217	In general, you cannot use an C<ev_run> from multiple threads or other
…		…
3106	it by calling C<ev_async_send>, which is thread- and signal safe.	3224	it by calling C<ev_async_send>, which is thread- and signal safe.
3107		3225
3108	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,
3109	too, are asynchronous in nature, and signals, too, will be compressed	3227	too, are asynchronous in nature, and signals, too, will be compressed
3110	(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
3111	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.
3112		3233
3113	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
3114	just the default loop.	3235	just the default loop.
3115		3236
3116	=head3 Queueing	3237	=head3 Queueing
…		…
3292	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
3293	the given events it.	3414	the given events it.
3294		3415
3295	=item ev_feed_signal_event (loop, int signum)	3416	=item ev_feed_signal_event (loop, int signum)
3296		3417
3297	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>,
3298	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;
3299		3470
3300	=back	3471	=back
3301		3472
3302		3473
3303	=head1 LIBEVENT EMULATION	3474	=head1 LIBEVENT EMULATION
3304		3475
3305	Libev offers a compatibility emulation layer for libevent. It cannot	3476	Libev offers a compatibility emulation layer for libevent. It cannot
3306	emulate the internals of libevent, so here are some usage hints:	3477	emulate the internals of libevent, so here are some usage hints:
3307		3478
3308	=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.
3309		3485
3310	=item * Use it by including <event.h>, as usual.	3486	=item * Use it by including <event.h>, as usual.
3311		3487
3312	=item * The following members are fully supported: ev_base, ev_callback,	3488	=item * The following members are fully supported: ev_base, ev_callback,
3313	ev_arg, ev_fd, ev_res, ev_events.	3489	ev_arg, ev_fd, ev_res, ev_events.
…		…
3319	=item * Priorities are not currently supported. Initialising priorities	3495	=item * Priorities are not currently supported. Initialising priorities
3320	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
3321	is an ev_pri field.	3497	is an ev_pri field.
3322		3498
3323	=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
3324	first base created (== the default loop) gets the signals.	3500	base that registered the signal gets the signals.
3325		3501
3326	=item * Other members are not supported.	3502	=item * Other members are not supported.
3327		3503
3328	=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
3329	to use the libev header file and library.	3505	to use the libev header file and library.
…		…
3348	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++
3349	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
3350	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
3351	you disable C<EV_MULTIPLICITY> when embedding libev).	3527	you disable C<EV_MULTIPLICITY> when embedding libev).
3352		3528
3353	Currently, functions, and static and non-static member functions can be	3529	Currently, functions, static and non-static member functions and classes
3354	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
3355	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
3356	types of functors please contact the author (preferably after implementing	3532	you need support for other types of functors please contact the author
3357	it).	3533	(preferably after implementing it).
3358		3534
3359	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:
3360		3536
3361	=over 4	3537	=over 4
3362		3538
…		…
4706	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
4707	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
4708	callback: The watcher callbacks have different type signatures, but libev	4884	callback: The watcher callbacks have different type signatures, but libev
4709	calls them using an C<ev_watcher *> internally.	4885	calls them using an C<ev_watcher *> internally.
4710		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.
		4891
4711	=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
4712		4893
4713	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
4714	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
4715	threads. This is not part of the specification for C<sig_atomic_t>, but is	4896	threads. This is not part of the specification for C<sig_atomic_t>, but is
…		…
4821	=back	5002	=back
4822		5003
4823		5004
4824	=head1 PORTING FROM LIBEV 3.X TO 4.X	5005	=head1 PORTING FROM LIBEV 3.X TO 4.X
4825		5006
4826	The major version 4 introduced some minor incompatible changes to the API.	5007	The major version 4 introduced some incompatible changes to the API.
4827		5008
4828	At the moment, the C<ev.h> header file tries to implement superficial	5009	At the moment, the C<ev.h> header file provides compatibility definitions
4829	compatibility, so most programs should still compile. Those might be	5010	for all changes, so most programs should still compile. The compatibility
4830	removed in later versions of libev, so better update early than late.	5011	layer might be removed in later versions of libev, so better update to the
		5012	new API early than late.
4831		5013
4832	=over 4	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);
4833		5028
4834	=item function/symbol renames	5029	=item function/symbol renames
4835		5030
4836	A number of functions and symbols have been renamed:	5031	A number of functions and symbols have been renamed:
4837		5032
…		…
4856	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme	5051	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
4857	as all other watcher types. Note that C<ev_loop_fork> is still called	5052	as all other watcher types. Note that C<ev_loop_fork> is still called
4858	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>	5053	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4859	typedef.	5054	typedef.
4860		5055
4861	=item C<EV_COMPAT3> backwards compatibility mechanism
4862
4863	The backward compatibility mechanism can be controlled by
4864	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
4865	section.
4866
4867	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	5056	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4868		5057
4869	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	5058	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4870	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	5059	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
4871	and work, but the library code will of course be larger.	5060	and work, but the library code will of course be larger.
…		…
4945		5134
4946	=back	5135	=back
4947		5136
4948	=head1 AUTHOR	5137	=head1 AUTHOR
4949		5138
4950	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.
4951		5141

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Comparing libev/ev.pod (file contents): Revision 1.319 by root, Fri Oct 22 10:09:12 2010 UTC vs. Revision 1.351 by root, Mon Jan 10 14:24:26 2011 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.319 by root, Fri Oct 22 10:09:12 2010 UTC vs.
Revision 1.351 by root, Mon Jan 10 14:24:26 2011 UTC