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

Comparing libev/ev.pod (file contents):
Revision 1.321 by sf-exg, Fri Oct 22 10:50:24 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
…		…
233	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 ()
234	& ev_supported_backends ()>, likewise for recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
235		243
236	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
237		245
238	=item ev_set_allocator (void (cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void (cb)(void *ptr, long size))
239		247
240	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
241	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
242	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
243	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
…		…
269	}	277	}
270		278
271	...	279	...
272	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
273		281
274	=item ev_set_syserr_cb (void (cb)(const char msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (cb)(const char msg))
275		283
276	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
277	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
278	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
279	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
…		…
291	}	299	}
292		300
293	...	301	...
294	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
295		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
296	=back	317	=back
297		318
298	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	319	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
299		320
300	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
301	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
302	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).
303		324
304	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
305	supports signals and child events, and dynamically created event loops	326	supports child process events, and dynamically created event loops which
306	which do not.	327	do not.
307		328
308	=over 4	329	=over 4
309		330
310	=item struct ev_loop *ev_default_loop (unsigned int flags)	331	=item struct ev_loop *ev_default_loop (unsigned int flags)
311		332
312	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
313	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
314	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
315	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".
316		343
317	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
318	function.	345	function (or via the C<EV_DEFAULT> macro).
319		346
320	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
321	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
322	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).
323		351
324	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,
325	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
326	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
327	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
328	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	356	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
329	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.
330		376
331	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
332	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>).
333		379
334	The following flags are supported:	380	The following flags are supported:
…		…
369	environment variable.	415	environment variable.
370		416
371	=item C<EVFLAG_NOINOTIFY>	417	=item C<EVFLAG_NOINOTIFY>
372		418
373	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
374	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
375	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
376	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.
377		423
378	=item C<EVFLAG_SIGNALFD>	424	=item C<EVFLAG_SIGNALFD>
379		425
380	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
381	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
382	delivers signals synchronously, which makes it both faster and might make	428	delivers signals synchronously, which makes it both faster and might make
383	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
384	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
385	threads that are not interested in handling them.	431	threads that are not interested in handling them.
386		432
387	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
388	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
389	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.
390		448
391	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
392		450
393	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
394	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,
…		…
430	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
431		489
432	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
433	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
434	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
435	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
436	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
437	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
438	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
439	hard to detect.	499	and is of course hard to detect.
440		500
441	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
442	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
443	I<different> file descriptors (even already closed ones, so one cannot	503	I<different> file descriptors (even already closed ones, so one cannot
444	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
…		…
446	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
447	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
448	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
449	perfectly fine with C<select> (files, many character devices...).	509	perfectly fine with C<select> (files, many character devices...).
450		510
		511	Epoll is truly the train wreck analog among event poll mechanisms.
		512
451	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
452	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
453	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
454	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
455	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
…		…
520	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	582	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
521		583
522	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,
523	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)).
524		586
525	Please note that Solaris event ports can deliver a lot of spurious
526	notifications, so you need to use non-blocking I/O or other means to avoid
527	blocking when no data (or space) is available.
528
529	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
530	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
531	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	589	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
532	might perform better.	590	might perform better.
533		591
534	On the positive side, with the exception of the spurious readiness	592	On the positive side, this backend actually performed fully to
535	notifications, this backend actually performed fully to specification
536	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
537	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.
538		606
539	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
540	C<EVBACKEND_POLL>.	608	C<EVBACKEND_POLL>.
541		609
542	=item C<EVBACKEND_ALL>	610	=item C<EVBACKEND_ALL>
543		611
544	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
545	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
546	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	614	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
547		615
548	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).
549		625
550	=back	626	=back
551		627
552	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,
553	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
554	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
555	()> will be tried.	631	()> will be tried.
556		632
557	Example: This is the most typical usage.
558
559	if (!ev_default_loop (0))
560	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
561
562	Example: Restrict libev to the select and poll backends, and do not allow
563	environment settings to be taken into account:
564
565	ev_default_loop (EVBACKEND_POLL \| EVBACKEND_SELECT \| EVFLAG_NOENV);
566
567	Example: Use whatever libev has to offer, but make sure that kqueue is
568	used if available (warning, breaks stuff, best use only with your own
569	private event loop and only if you know the OS supports your types of
570	fds):
571
572	ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);
573
574	=item struct ev_loop *ev_loop_new (unsigned int flags)
575
576	Similar to C<ev_default_loop>, but always creates a new event loop that is
577	always distinct from the default loop.
578
579	Note that this function I<is> thread-safe, and one common way to use
580	libev with threads is indeed to create one loop per thread, and using the
581	default loop in the "main" or "initial" thread.
582
583	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.
584		634
585	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	635	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
586	if (!epoller)	636	if (!epoller)
587	fatal ("no epoll found here, maybe it hides under your chair");	637	fatal ("no epoll found here, maybe it hides under your chair");
588		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
589	=item ev_default_destroy ()	644	=item ev_loop_destroy (loop)
590		645
591	Destroys the default loop (frees all memory and kernel state etc.). None	646	Destroys an event loop object (frees all memory and kernel state
592	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
593	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
594	either stop all watchers cleanly yourself I<before> calling this function,	649	responsibility to either stop all watchers cleanly yourself I<before>
595	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
596	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).
597		653
598	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
599	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
600	as signal and child watchers) would need to be stopped manually.	656	as signal and child watchers) would need to be stopped manually.
601		657
602	In general it is not advisable to call this function except in the	658	This function is normally used on loop objects allocated by
603	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.
604	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>
605	C<ev_loop_new> and C<ev_loop_destroy>.	665	and C<ev_loop_destroy>.
606		666
607	=item ev_loop_destroy (loop)	667	=item ev_loop_fork (loop)
608		668
609	Like C<ev_default_destroy>, but destroys an event loop created by an
610	earlier call to C<ev_loop_new>.
611
612	=item ev_default_fork ()
613
614	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
615	to reinitialise the kernel state for backends that have one. Despite the	670	reinitialise the kernel state for backends that have one. Despite the
616	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
617	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
618	sense). You I<must> call it in the child before using any of the libev	673	child before resuming or calling C<ev_run>.
619	functions, and it will only take effect at the next C<ev_run> iteration.
620		674
621	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
622	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
623	because some kernel interfaces cough I<kqueue> cough do funny things	677	because some kernel interfaces cough I<kqueue> cough do funny things
624	during fork.	678	during fork.
…		…
629	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
630	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
631	costly reset of the backend).	685	costly reset of the backend).
632		686
633	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
634	it just in case after a fork. To make this easy, the function will fit in	688	it just in case after a fork.
635	quite nicely into a call to C<pthread_atfork>:
636		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	...
637	pthread_atfork (0, 0, ev_default_fork);	700	pthread_atfork (0, 0, post_fork_child);
638
639	=item ev_loop_fork (loop)
640
641	Like C<ev_default_fork>, but acts on an event loop created by
642	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
643	after fork that you want to re-use in the child, and how you keep track of
644	them is entirely your own problem.
645		701
646	=item int ev_is_default_loop (loop)	702	=item int ev_is_default_loop (loop)
647		703
648	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
649	otherwise.	705	otherwise.
…		…
660	prepare and check phases.	716	prepare and check phases.
661		717
662	=item unsigned int ev_depth (loop)	718	=item unsigned int ev_depth (loop)
663		719
664	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
665	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.
666		722
667	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
668	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),
669	in which case it is higher.	725	in which case it is higher.
670		726
671	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread	727	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
672	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
673	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.
674		731
675	=item unsigned int ev_backend (loop)	732	=item unsigned int ev_backend (loop)
676		733
677	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
678	use.	735	use.
…		…
739	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
740	finished (especially in interactive programs), but having a program	797	finished (especially in interactive programs), but having a program
741	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
742	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
743	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.
744		806
745	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
746	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
747	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
748	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
…		…
810	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
811	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
812	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
813	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.
814		876
815	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>.
816		878
817	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.
818		881
819	=item ev_ref (loop)	882	=item ev_ref (loop)
820		883
821	=item ev_unref (loop)	884	=item ev_unref (loop)
822		885
…		…
843	running when nothing else is active.	906	running when nothing else is active.
844		907
845	ev_signal exitsig;	908	ev_signal exitsig;
846	ev_signal_init (&exitsig, sig_cb, SIGINT);	909	ev_signal_init (&exitsig, sig_cb, SIGINT);
847	ev_signal_start (loop, &exitsig);	910	ev_signal_start (loop, &exitsig);
848	evf_unref (loop);	911	ev_unref (loop);
849		912
850	Example: For some weird reason, unregister the above signal handler again.	913	Example: For some weird reason, unregister the above signal handler again.
851		914
852	ev_ref (loop);	915	ev_ref (loop);
853	ev_signal_stop (loop, &exitsig);	916	ev_signal_stop (loop, &exitsig);
…		…
965	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
966	document.	1029	document.
967		1030
968	=item ev_set_userdata (loop, void *data)	1031	=item ev_set_userdata (loop, void *data)
969		1032
970	=item ev_userdata (loop)	1033	=item void *ev_userdata (loop)
971		1034
972	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
973	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
974	C<0.>	1037	C<0>.
975		1038
976	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,
977	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
978	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
979	any other purpose as well.	1042	any other purpose as well.
…		…
1107	=item C<EV_FORK>	1170	=item C<EV_FORK>
1108		1171
1109	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
1110	C<ev_fork>).	1173	C<ev_fork>).
1111		1174
		1175	=item C<EV_CLEANUP>
		1176
		1177	The event loop is about to be destroyed (see C<ev_cleanup>).
		1178
1112	=item C<EV_ASYNC>	1179	=item C<EV_ASYNC>
1113		1180
1114	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>).
1115		1182
1116	=item C<EV_CUSTOM>	1183	=item C<EV_CUSTOM>
…		…
1137	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
1138	thing, so beware.	1205	thing, so beware.
1139		1206
1140	=back	1207	=back
1141		1208
1142	=head2 WATCHER STATES
1143
1144	There are various watcher states mentioned throughout this manual -
1145	active, pending and so on. In this section these states and the rules to
1146	transition between them will be described in more detail - and while these
1147	rules might look complicated, they usually do "the right thing".
1148
1149	=over 4
1150
1151	=item initialiased
1152
1153	Before a watcher can be registered with the event looop it has to be
1154	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
1155	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
1156
1157	In this state it is simply some block of memory that is suitable for use
1158	in an event loop. It can be moved around, freed, reused etc. at will.
1159
1160	=item started/running/active
1161
1162	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
1163	property of the event loop, and is actively waiting for events. While in
1164	this state it cannot be accessed (except in a few documented ways), moved,
1165	freed or anything else - the only legal thing is to keep a pointer to it,
1166	and call libev functions on it that are documented to work on active watchers.
1167
1168	=item pending
1169
1170	If a watcher is active and libev determines that an event it is interested
1171	in has occurred (such as a timer expiring), it will become pending. It will
1172	stay in this pending state until either it is stopped or its callback is
1173	about to be invoked, so it is not normally pending inside the watcher
1174	callback.
1175
1176	The watcher might or might not be active while it is pending (for example,
1177	an expired non-repeating timer can be pending but no longer active). If it
1178	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
1179	but it is still property of the event loop at this time, so cannot be
1180	moved, freed or reused. And if it is active the rules described in the
1181	previous item still apply.
1182
1183	It is also possible to feed an event on a watcher that is not active (e.g.
1184	via C<ev_feed_event>), in which case it becomes pending without being
1185	active.
1186
1187	=item stopped
1188
1189	A watcher can be stopped implicitly by libev (in which case it might still
1190	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
1191	latter will clear any pending state the watcher might be in, regardless
1192	of whether it was active or not, so stopping a watcher explicitly before
1193	freeing it is often a good idea.
1194
1195	While stopped (and not pending) the watcher is essentially in the
1196	initialised state, that is it can be reused, moved, modified in any way
1197	you wish.
1198
1199	=back
1200
1201	=head2 GENERIC WATCHER FUNCTIONS	1209	=head2 GENERIC WATCHER FUNCTIONS
1202		1210
1203	=over 4	1211	=over 4
1204		1212
1205	=item C<ev_init> (ev_TYPE *watcher, callback)	1213	=item C<ev_init> (ev_TYPE *watcher, callback)
…		…
1346		1354
1347	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
1348	functions that do not need a watcher.	1356	functions that do not need a watcher.
1349		1357
1350	=back	1358	=back
1351
1352		1359
1353	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1360	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1354		1361
1355	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
1356	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
…		…
1412	t2_cb (EV_P_ ev_timer *w, int revents)	1419	t2_cb (EV_P_ ev_timer *w, int revents)
1413	{	1420	{
1414	struct my_biggy big = (struct my_biggy *)	1421	struct my_biggy big = (struct my_biggy *)
1415	(((char *)w) - offsetof (struct my_biggy, t2));	1422	(((char *)w) - offsetof (struct my_biggy, t2));
1416	}	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
1417		1483
1418	=head2 WATCHER PRIORITY MODELS	1484	=head2 WATCHER PRIORITY MODELS
1419		1485
1420	Many event loops support I<watcher priorities>, which are usually small	1486	Many event loops support I<watcher priorities>, which are usually small
1421	integers that influence the ordering of event callback invocation	1487	integers that influence the ordering of event callback invocation
…		…
2240		2306
2241	=head2 C<ev_signal> - signal me when a signal gets signalled!	2307	=head2 C<ev_signal> - signal me when a signal gets signalled!
2242		2308
2243	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
2244	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
2245	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
2246	normal event processing, like any other event.	2312	normal event processing, like any other event.
2247		2313
2248	If you want signals to be delivered truly asynchronously, just use	2314	If you want signals to be delivered truly asynchronously, just use
2249	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
2250	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
…		…
2292	I<has> to modify the signal mask, at least temporarily.	2358	I<has> to modify the signal mask, at least temporarily.
2293		2359
2294	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
2295	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
2296	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>.
2297		2377
2298	=head3 Watcher-Specific Functions and Data Members	2378	=head3 Watcher-Specific Functions and Data Members
2299		2379
2300	=over 4	2380	=over 4
2301		2381
…		…
3075	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
3076	signal watchers).	3156	signal watchers).
3077		3157
3078	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
3079	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
3080	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3160	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
3081	the default loop will "orphan" (not stop) all registered watchers, so you	3161	Destroying the default loop will "orphan" (not stop) all registered
3082	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
3083	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.
3084		3165
3085	=head3 Watcher-Specific Functions and Data Members	3166	=head3 Watcher-Specific Functions and Data Members
3086		3167
3087	=over 4	3168	=over 4
3088		3169
3089	=item ev_fork_init (ev_signal *, callback)	3170	=item ev_fork_init (ev_fork *, callback)
3090		3171
3091	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
3092	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,
3093	believe me.	3174	really.
3094		3175
3095	=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);
3096		3217
3097		3218
3098	=head2 C<ev_async> - how to wake up an event loop	3219	=head2 C<ev_async> - how to wake up an event loop
3099		3220
3100	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
…		…
3107	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.
3108		3229
3109	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,
3110	too, are asynchronous in nature, and signals, too, will be compressed	3231	too, are asynchronous in nature, and signals, too, will be compressed
3111	(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
3112	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.
3113		3237
3114	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
3115	just the default loop.	3239	just the default loop.
3116		3240
3117	=head3 Queueing	3241	=head3 Queueing
…		…
3293	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
3294	the given events it.	3418	the given events it.
3295		3419
3296	=item ev_feed_signal_event (loop, int signum)	3420	=item ev_feed_signal_event (loop, int signum)
3297		3421
3298	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>,
3299	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;
3300		3474
3301	=back	3475	=back
3302		3476
3303		3477
3304	=head1 LIBEVENT EMULATION	3478	=head1 LIBEVENT EMULATION
3305		3479
3306	Libev offers a compatibility emulation layer for libevent. It cannot	3480	Libev offers a compatibility emulation layer for libevent. It cannot
3307	emulate the internals of libevent, so here are some usage hints:	3481	emulate the internals of libevent, so here are some usage hints:
3308		3482
3309	=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.
3310		3489
3311	=item * Use it by including <event.h>, as usual.	3490	=item * Use it by including <event.h>, as usual.
3312		3491
3313	=item * The following members are fully supported: ev_base, ev_callback,	3492	=item * The following members are fully supported: ev_base, ev_callback,
3314	ev_arg, ev_fd, ev_res, ev_events.	3493	ev_arg, ev_fd, ev_res, ev_events.
…		…
3320	=item * Priorities are not currently supported. Initialising priorities	3499	=item * Priorities are not currently supported. Initialising priorities
3321	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
3322	is an ev_pri field.	3501	is an ev_pri field.
3323		3502
3324	=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
3325	first base created (== the default loop) gets the signals.	3504	base that registered the signal gets the signals.
3326		3505
3327	=item * Other members are not supported.	3506	=item * Other members are not supported.
3328		3507
3329	=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
3330	to use the libev header file and library.	3509	to use the libev header file and library.
…		…
3349	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++
3350	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
3351	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
3352	you disable C<EV_MULTIPLICITY> when embedding libev).	3531	you disable C<EV_MULTIPLICITY> when embedding libev).
3353		3532
3354	Currently, functions, and static and non-static member functions can be	3533	Currently, functions, static and non-static member functions and classes
3355	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
3356	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
3357	types of functors please contact the author (preferably after implementing	3536	you need support for other types of functors please contact the author
3358	it).	3537	(preferably after implementing it).
3359		3538
3360	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:
3361		3540
3362	=over 4	3541	=over 4
3363		3542
…		…
4707	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
4708	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
4709	callback: The watcher callbacks have different type signatures, but libev	4888	callback: The watcher callbacks have different type signatures, but libev
4710	calls them using an C<ev_watcher *> internally.	4889	calls them using an C<ev_watcher *> internally.
4711		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
4712	=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
4713		4897
4714	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
4715	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
4716	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
…		…
4822	=back	5006	=back
4823		5007
4824		5008
4825	=head1 PORTING FROM LIBEV 3.X TO 4.X	5009	=head1 PORTING FROM LIBEV 3.X TO 4.X
4826		5010
4827	The major version 4 introduced some minor incompatible changes to the API.	5011	The major version 4 introduced some incompatible changes to the API.
4828		5012
4829	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
4830	compatibility, so most programs should still compile. Those might be	5014	for all changes, so most programs should still compile. The compatibility
4831	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.
4832		5017
4833	=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);
4834		5032
4835	=item function/symbol renames	5033	=item function/symbol renames
4836		5034
4837	A number of functions and symbols have been renamed:	5035	A number of functions and symbols have been renamed:
4838		5036
…		…
4857	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
4858	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
4859	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>
4860	typedef.	5058	typedef.
4861		5059
4862	=item C<EV_COMPAT3> backwards compatibility mechanism
4863
4864	The backward compatibility mechanism can be controlled by
4865	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
4866	section.
4867
4868	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	5060	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4869		5061
4870	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
4871	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	5063	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
4872	and work, but the library code will of course be larger.	5064	and work, but the library code will of course be larger.
…		…
4946		5138
4947	=back	5139	=back
4948		5140
4949	=head1 AUTHOR	5141	=head1 AUTHOR
4950		5142
4951	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.
4952		5145

Diff Legend

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

Comparing libev/ev.pod (file contents): Revision 1.321 by sf-exg, Fri Oct 22 10:50:24 2010 UTC vs. Revision 1.352 by root, Mon Jan 10 14:30:15 2011 UTC

Diff Legend

Comparing libev/ev.pod (file contents):
Revision 1.321 by sf-exg, Fri Oct 22 10:50:24 2010 UTC vs.
Revision 1.352 by root, Mon Jan 10 14:30:15 2011 UTC