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Revision 1.173 by root, Mon Jul 21 03:47:22 2008 UTC vs.
Revision 1.343 by root, Wed Dec 29 04:27:53 2010 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# if you prefer function calls, look at the AE manpage for
		13	# an alternative API.
		14
		15	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
12		17
		18	# one-shot or repeating timers
13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
15		21
16	print AnyEvent->now; # prints current event loop time	22	print AnyEvent->now; # prints current event loop time
17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18		24
		25	# POSIX signal
19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });	26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20		27
		28	# child process exit
21	my $w = AnyEvent->child (pid => $pid, cb => sub {	29	my $w = AnyEvent->child (pid => $pid, cb => sub {
22	my ($pid, $status) = @_;	30	my ($pid, $status) = @_;
23	...	31	...
24	});	32	});
		33
		34	# called when event loop idle (if applicable)
		35	my $w = AnyEvent->idle (cb => sub { ... });
25		36
26	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
27	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
28	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
29	# use a condvar in callback mode:	40	# use a condvar in callback mode:
…		…
32	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
33		44
34	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
35	in a tutorial or some gentle introduction, have a look at the	46	in a tutorial or some gentle introduction, have a look at the
36	L<AnyEvent::Intro> manpage.	47	L<AnyEvent::Intro> manpage.
		48
		49	=head1 SUPPORT
		50
		51	An FAQ document is available as L<AnyEvent::FAQ>.
		52
		53	There also is a mailinglist for discussing all things AnyEvent, and an IRC
		54	channel, too.
		55
		56	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		57	Repository>, at L<http://anyevent.schmorp.de>, for more info.
37		58
38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
39		60
40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	61	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
41	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
…		…
57	module users into the same thing by forcing them to use the same event	78	module users into the same thing by forcing them to use the same event
58	model you use.	79	model you use.
59		80
60	For modules like POE or IO::Async (which is a total misnomer as it is	81	For modules like POE or IO::Async (which is a total misnomer as it is
61	actually doing all I/O I<synchronously>...), using them in your module is	82	actually doing all I/O I<synchronously>...), using them in your module is
62	like joining a cult: After you joined, you are dependent on them and you	83	like joining a cult: After you join, you are dependent on them and you
63	cannot use anything else, as they are simply incompatible to everything	84	cannot use anything else, as they are simply incompatible to everything
64	that isn't them. What's worse, all the potential users of your	85	that isn't them. What's worse, all the potential users of your
65	module are I<also> forced to use the same event loop you use.	86	module are I<also> forced to use the same event loop you use.
66		87
67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
68	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	89	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
69	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	90	with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
70	your module uses one of those, every user of your module has to use it,	91	uses one of those, every user of your module has to use it, too. But if
71	too. But if your module uses AnyEvent, it works transparently with all	92	your module uses AnyEvent, it works transparently with all event models it
72	event models it supports (including stuff like IO::Async, as long as those	93	supports (including stuff like IO::Async, as long as those use one of the
73	use one of the supported event loops. It is trivial to add new event loops	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
74	to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
75		96
76	In addition to being free of having to use I<the one and only true event	97	In addition to being free of having to use I<the one and only true event
77	model>, AnyEvent also is free of bloat and policy: with POE or similar	98	model>, AnyEvent also is free of bloat and policy: with POE or similar
78	modules, you get an enormous amount of code and strict rules you have to	99	modules, you get an enormous amount of code and strict rules you have to
79	follow. AnyEvent, on the other hand, is lean and up to the point, by only	100	follow. AnyEvent, on the other hand, is lean and to the point, by only
80	offering the functionality that is necessary, in as thin as a wrapper as	101	offering the functionality that is necessary, in as thin as a wrapper as
81	technically possible.	102	technically possible.
82		103
83	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
84	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
90	useful) and you want to force your users to use the one and only event	111	useful) and you want to force your users to use the one and only event
91	model, you should I<not> use this module.	112	model, you should I<not> use this module.
92		113
93	=head1 DESCRIPTION	114	=head1 DESCRIPTION
94		115
95	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
96	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
97	users to use the same event loop (as only a single event loop can coexist	118	module users to use a specific event loop implementation (since more
98	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
99		120
100	The interface itself is vaguely similar, but not identical to the L<Event>	121	The interface itself is vaguely similar, but not identical to the L<Event>
101	module.	122	module.
102		123
103	During the first call of any watcher-creation method, the module tries	124	During the first call of any watcher-creation method, the module tries
104	to detect the currently loaded event loop by probing whether one of the	125	to detect the currently loaded event loop by probing whether one of the
105	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Impl::Perl>,
106	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	127	L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
107	L<POE>. The first one found is used. If none are found, the module tries	128	found is used. If none are detected, the module tries to load the first
108	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	129	four modules in the order given; but note that if L<EV> is not
109	adaptor should always succeed) in the order given. The first one that can	130	available, the pure-perl L<AnyEvent::Impl::Perl> should always work, so
110	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
111	found, AnyEvent will fall back to a pure-perl event loop, which is not
112	very efficient, but should work everywhere.
113		132
114	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
115	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
116	that model the default. For example:	135	that model the default. For example:
117		136
…		…
119	use AnyEvent;	138	use AnyEvent;
120		139
121	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
122		141
123	The I<likely> means that, if any module loads another event model and	142	The I<likely> means that, if any module loads another event model and
124	starts using it, all bets are off. Maybe you should tell their authors to	143	starts using it, all bets are off - this case should be very rare though,
125	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
126		146
127	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called
128	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	148	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
129	explicitly and enjoy the high availability of that event loop :)	149	explicitly and enjoy the high availability of that event loop :)
130		150
…		…
137	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
138	creating a watcher it will immediately "watch" for events and invoke the	158	creating a watcher it will immediately "watch" for events and invoke the
139	callback when the event occurs (of course, only when the event model	159	callback when the event occurs (of course, only when the event model
140	is in control).	160	is in control).
141		161
		162	Note that B<callbacks must not permanently change global variables>
		163	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		164	callbacks must not C<die> >>. The former is good programming practice in
		165	Perl and the latter stems from the fact that exception handling differs
		166	widely between event loops.
		167
142	To disable the watcher you have to destroy it (e.g. by setting the	168	To disable a watcher you have to destroy it (e.g. by setting the
143	variable you store it in to C<undef> or otherwise deleting all references	169	variable you store it in to C<undef> or otherwise deleting all references
144	to it).	170	to it).
145		171
146	All watchers are created by calling a method on the C<AnyEvent> class.	172	All watchers are created by calling a method on the C<AnyEvent> class.
147		173
148	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
149	example), or need to refer to their watcher object in other ways.	175	example), or need to refer to their watcher object in other ways.
150		176
151	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
152		178
153	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
154	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
155	undef $w;	181	undef $w;
156	});	182	});
…		…
159	my variables are only visible after the statement in which they are	185	my variables are only visible after the statement in which they are
160	declared.	186	declared.
161		187
162	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
163		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
164	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	196	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
165	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
166		198
167	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
168	(AnyEvent might or might not keep a reference to this file handle). C<poll>	200	for events (AnyEvent might or might not keep a reference to this file
		201	handle). Note that only file handles pointing to things for which
		202	non-blocking operation makes sense are allowed. This includes sockets,
		203	most character devices, pipes, fifos and so on, but not for example files
		204	or block devices.
		205
169	must be a string that is either C<r> or C<w>, which creates a watcher	206	C<poll> must be a string that is either C<r> or C<w>, which creates a
170	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
171	callback to invoke each time the file handle becomes ready.	209	C<cb> is the callback to invoke each time the file handle becomes ready.
172		210
173	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
174	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
175	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
176		214
177	The I/O watcher might use the underlying file descriptor or a copy of it.	215	The I/O watcher might use the underlying file descriptor or a copy of it.
178	You must not close a file handle as long as any watcher is active on the	216	You must not close a file handle as long as any watcher is active on the
179	underlying file descriptor.	217	underlying file descriptor.
180		218
181	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
182	always use non-blocking calls when reading/writing from/to your file	220	always use non-blocking calls when reading/writing from/to your file
183	handles.	221	handles.
184		222
185	Example: wait for readability of STDIN, then read a line and disable the	223	Example: wait for readability of STDIN, then read a line and disable the
186	watcher.	224	watcher.
…		…
191	undef $w;	229	undef $w;
192	});	230	});
193		231
194	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
195		233
		234	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		235
		236	$w = AnyEvent->timer (
		237	after => <fractional_seconds>,
		238	interval => <fractional_seconds>,
		239	cb => <callback>,
		240	);
		241
196	You can create a time watcher by calling the C<< AnyEvent->timer >>	242	You can create a time watcher by calling the C<< AnyEvent->timer >>
197	method with the following mandatory arguments:	243	method with the following mandatory arguments:
198		244
199	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
200	supported) the callback should be invoked. C<cb> is the callback to invoke	246	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
202		248
203	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
204	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
205	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
206		252
207	The callback will normally be invoked once only. If you specify another	253	The callback will normally be invoked only once. If you specify another
208	parameter, C<interval>, as a strictly positive number (> 0), then the	254	parameter, C<interval>, as a strictly positive number (> 0), then the
209	callback will be invoked regularly at that interval (in fractional	255	callback will be invoked regularly at that interval (in fractional
210	seconds) after the first invocation. If C<interval> is specified with a	256	seconds) after the first invocation. If C<interval> is specified with a
211	false value, then it is treated as if it were missing.	257	false value, then it is treated as if it were not specified at all.
212		258
213	The callback will be rescheduled before invoking the callback, but no	259	The callback will be rescheduled before invoking the callback, but no
214	attempt is done to avoid timer drift in most backends, so the interval is	260	attempt is made to avoid timer drift in most backends, so the interval is
215	only approximate.	261	only approximate.
216		262
217	Example: fire an event after 7.7 seconds.	263	Example: fire an event after 7.7 seconds.
218		264
219	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
237		283
238	While most event loops expect timers to specified in a relative way, they	284	While most event loops expect timers to specified in a relative way, they
239	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
240	"jumps", for example, when ntp decides to set your clock backwards from	286	"jumps", for example, when ntp decides to set your clock backwards from
241	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to	287	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
242	fire "after" a second might actually take six years to finally fire.	288	fire "after a second" might actually take six years to finally fire.
243		289
244	AnyEvent cannot compensate for this. The only event loop that is conscious	290	AnyEvent cannot compensate for this. The only event loop that is conscious
245	about these issues is L<EV>, which offers both relative (ev_timer, based	291	of these issues is L<EV>, which offers both relative (ev_timer, based
246	on true relative time) and absolute (ev_periodic, based on wallclock time)	292	on true relative time) and absolute (ev_periodic, based on wallclock time)
247	timers.	293	timers.
248		294
249	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
250	AnyEvent API.	296	AnyEvent API.
…		…
272	I<In almost all cases (in all cases if you don't care), this is the	318	I<In almost all cases (in all cases if you don't care), this is the
273	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
274		320
275	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
276	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
277	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
278		324
279	The rest of this section is only of relevance if you try to be very exact	325	The rest of this section is only of relevance if you try to be very exact
280	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
281		327
282	For a practical example of when these times differ, consider L<Event::Lib>	328	For a practical example of when these times differ, consider L<Event::Lib>
283	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
284		330
285	The event loop is running and has just invoked one of your callback at	331	The event loop is running and has just invoked one of your callbacks at
286	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
287	you wait a second by executing C<sleep 1> (blocking the process for a	333	you wait a second by executing C<sleep 1> (blocking the process for a
288	second) and then (at time=501) you create a relative timer that fires	334	second) and then (at time=501) you create a relative timer that fires
289	after three seconds.	335	after three seconds.
290		336
…		…
308	In either case, if you care (and in most cases, you don't), then you	354	In either case, if you care (and in most cases, you don't), then you
309	can get whatever behaviour you want with any event loop, by taking the	355	can get whatever behaviour you want with any event loop, by taking the
310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311	account.	357	account.
312		358
		359	=item AnyEvent->now_update
		360
		361	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		362	the current time for each loop iteration (see the discussion of L<<
		363	AnyEvent->now >>, above).
		364
		365	When a callback runs for a long time (or when the process sleeps), then
		366	this "current" time will differ substantially from the real time, which
		367	might affect timers and time-outs.
		368
		369	When this is the case, you can call this method, which will update the
		370	event loop's idea of "current time".
		371
		372	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		373	when mod_perl executes the script, then the event loop will have the wrong
		374	idea about the "current time" (being potentially far in the past, when the
		375	script ran the last time). In that case you should arrange a call to C<<
		376	AnyEvent->now_update >> each time the web server process wakes up again
		377	(e.g. at the start of your script, or in a handler).
		378
		379	Note that updating the time I<might> cause some events to be handled.
		380
313	=back	381	=back
314		382
315	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
316		386
317	You can watch for signals using a signal watcher, C<signal> is the signal	387	You can watch for signals using a signal watcher, C<signal> is the signal
318	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl	388	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
319	callback to be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
320		390
…		…
326	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
327	that it might take a while until the signal gets handled by the process,	397	that it might take a while until the signal gets handled by the process,
328	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
329		399
330	The main advantage of using these watchers is that you can share a signal	400	The main advantage of using these watchers is that you can share a signal
331	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
332		403
333	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
334	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
335		407
336	Example: exit on SIGINT	408	Example: exit on SIGINT
337		409
338	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
339		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		437	variable can be changed only before the first signal watcher is created,
		438	and should be left alone otherwise. This variable determines how often
		439	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		440	will cause fewer spurious wake-ups, which is better for power and CPU
		441	saving.
		442
		443	All these problems can be avoided by installing the optional
		444	L<Async::Interrupt> module, which works with most event loops. It will not
		445	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		446	(and not with L<POE> currently, as POE does its own workaround with
		447	one-second latency). For those, you just have to suffer the delays.
		448
340	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
341		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
342	You can also watch on a child process exit and catch its exit status.	453	You can also watch for a child process exit and catch its exit status.
343		454
344	The child process is specified by the C<pid> argument (if set to C<0>, it	455	The child process is specified by the C<pid> argument (on some backends,
345	watches for any child process exit). The watcher will trigger as often	456	using C<0> watches for any child process exit, on others this will
346	as status change for the child are received. This works by installing a	457	croak). The watcher will be triggered only when the child process has
347	signal handler for C<SIGCHLD>. The callback will be called with the pid	458	finished and an exit status is available, not on any trace events
348	and exit status (as returned by waitpid), so unlike other watcher types,	459	(stopped/continued).
349	you I<can> rely on child watcher callback arguments.	460
		461	The callback will be called with the pid and exit status (as returned by
		462	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		463	callback arguments.
		464
		465	This watcher type works by installing a signal handler for C<SIGCHLD>,
		466	and since it cannot be shared, nothing else should use SIGCHLD or reap
		467	random child processes (waiting for specific child processes, e.g. inside
		468	C<system>, is just fine).
350		469
351	There is a slight catch to child watchers, however: you usually start them	470	There is a slight catch to child watchers, however: you usually start them
352	I<after> the child process was created, and this means the process could	471	I<after> the child process was created, and this means the process could
353	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
354		473
355	Not all event models handle this correctly (POE doesn't), but even for	474	Not all event models handle this correctly (neither POE nor IO::Async do,
		475	see their AnyEvent::Impl manpages for details), but even for event models
356	event models that I<do> handle this correctly, they usually need to be	476	that I<do> handle this correctly, they usually need to be loaded before
357	loaded before the process exits (i.e. before you fork in the first place).	477	the process exits (i.e. before you fork in the first place). AnyEvent's
		478	pure perl event loop handles all cases correctly regardless of when you
		479	start the watcher.
358		480
359	This means you cannot create a child watcher as the very first thing in an	481	This means you cannot create a child watcher as the very first
360	AnyEvent program, you I<have> to create at least one watcher before you	482	thing in an AnyEvent program, you I<have> to create at least one
361	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	483	watcher before you C<fork> the child (alternatively, you can call
		484	C<AnyEvent::detect>).
		485
		486	As most event loops do not support waiting for child events, they will be
		487	emulated by AnyEvent in most cases, in which the latency and race problems
		488	mentioned in the description of signal watchers apply.
362		489
363	Example: fork a process and wait for it	490	Example: fork a process and wait for it
364		491
365	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
366		493
…		…
376	);	503	);
377		504
378	# do something else, then wait for process exit	505	# do something else, then wait for process exit
379	$done->recv;	506	$done->recv;
380		507
		508	=head2 IDLE WATCHERS
		509
		510	$w = AnyEvent->idle (cb => <callback>);
		511
		512	This will repeatedly invoke the callback after the process becomes idle,
		513	until either the watcher is destroyed or new events have been detected.
		514
		515	Idle watchers are useful when there is a need to do something, but it
		516	is not so important (or wise) to do it instantly. The callback will be
		517	invoked only when there is "nothing better to do", which is usually
		518	defined as "all outstanding events have been handled and no new events
		519	have been detected". That means that idle watchers ideally get invoked
		520	when the event loop has just polled for new events but none have been
		521	detected. Instead of blocking to wait for more events, the idle watchers
		522	will be invoked.
		523
		524	Unfortunately, most event loops do not really support idle watchers (only
		525	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		526	will simply call the callback "from time to time".
		527
		528	Example: read lines from STDIN, but only process them when the
		529	program is otherwise idle:
		530
		531	my @lines; # read data
		532	my $idle_w;
		533	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		534	push @lines, scalar <STDIN>;
		535
		536	# start an idle watcher, if not already done
		537	$idle_w ||= AnyEvent->idle (cb => sub {
		538	# handle only one line, when there are lines left
		539	if (my $line = shift @lines) {
		540	print "handled when idle: $line";
		541	} else {
		542	# otherwise disable the idle watcher again
		543	undef $idle_w;
		544	}
		545	});
		546	});
		547
381	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
382		554
383	If you are familiar with some event loops you will know that all of them	555	If you are familiar with some event loops you will know that all of them
384	require you to run some blocking "loop", "run" or similar function that	556	require you to run some blocking "loop", "run" or similar function that
385	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
386		558
387	AnyEvent is different, it expects somebody else to run the event loop and	559	AnyEvent is slightly different: it expects somebody else to run the event
388	will only block when necessary (usually when told by the user).	560	loop and will only block when necessary (usually when told by the user).
389		561
390	The instrument to do that is called a "condition variable", so called	562	The tool to do that is called a "condition variable", so called because
391	because they represent a condition that must become true.	563	they represent a condition that must become true.
		564
		565	Now is probably a good time to look at the examples further below.
392		566
393	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
394
395	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
396
397	C<cb>, which specifies a callback to be called when the condition variable	569	C<cb>, which specifies a callback to be called when the condition variable
398	becomes true, with the condition variable as the first argument (but not	570	becomes true, with the condition variable as the first argument (but not
399	the results).	571	the results).
400		572
401	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
402	by calling the C<send> method (or calling the condition variable as if it	574	by calling the C<send> method (or calling the condition variable as if it
403	were a callback, read about the caveats in the description for the C<<	575	were a callback, read about the caveats in the description for the C<<
404	->send >> method).	576	->send >> method).
405		577
406	Condition variables are similar to callbacks, except that you can	578	Since condition variables are the most complex part of the AnyEvent API, here are
407	optionally wait for them. They can also be called merge points - points	579	some different mental models of what they are - pick the ones you can connect to:
408	in time where multiple outstanding events have been processed. And yet	580
409	another way to call them is transactions - each condition variable can be	581	=over 4
410	used to represent a transaction, which finishes at some point and delivers	582
411	a result.	583	=item * Condition variables are like callbacks - you can call them (and pass them instead
		584	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		585
		586	=item * Condition variables are signals - one side can emit or send them,
		587	the other side can wait for them, or install a handler that is called when
		588	the signal fires.
		589
		590	=item * Condition variables are like "Merge Points" - points in your program
		591	where you merge multiple independent results/control flows into one.
		592
		593	=item * Condition variables represent a transaction - functions that start
		594	some kind of transaction can return them, leaving the caller the choice
		595	between waiting in a blocking fashion, or setting a callback.
		596
		597	=item * Condition variables represent future values, or promises to deliver
		598	some result, long before the result is available.
		599
		600	=back
412		601
413	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
414	for example, if you write a module that does asynchronous http requests,	603	for example, if you write a module that does asynchronous http requests,
415	then a condition variable would be the ideal candidate to signal the	604	then a condition variable would be the ideal candidate to signal the
416	availability of results. The user can either act when the callback is	605	availability of results. The user can either act when the callback is
…		…
429		618
430	Condition variables are represented by hash refs in perl, and the keys	619	Condition variables are represented by hash refs in perl, and the keys
431	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	620	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
432	easy (it is often useful to build your own transaction class on top of	621	easy (it is often useful to build your own transaction class on top of
433	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	622	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
434	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
435		624
436	There are two "sides" to a condition variable - the "producer side" which	625	There are two "sides" to a condition variable - the "producer side" which
437	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
438	for the send to occur.	627	for the send to occur.
439		628
440	Example: wait for a timer.	629	Example: wait for a timer.
441		630
442	# wait till the result is ready	631	# condition: "wait till the timer is fired"
443	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
444		633
445	# do something such as adding a timer	634	# create the timer - we could wait for, say
446	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
447	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
448	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
449	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
450	after => 1,	639	after => 1,
451	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
452	);	641	);
453		642
454	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
455	# calls send	644	# calls ->send
456	$result_ready->recv;	645	$timer_fired->recv;
457		646
458	Example: wait for a timer, but take advantage of the fact that	647	Example: wait for a timer, but take advantage of the fact that condition
459	condition variables are also code references.	648	variables are also callable directly.
460		649
461	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
462	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
463	$done->recv;	652	$done->recv;
464		653
…		…
470		659
471	...	660	...
472		661
473	my @info = $couchdb->info->recv;	662	my @info = $couchdb->info->recv;
474		663
475	And this is how you would just ste a callback to be called whenever the	664	And this is how you would just set a callback to be called whenever the
476	results are available:	665	results are available:
477		666
478	$couchdb->info->cb (sub {	667	$couchdb->info->cb (sub {
479	my @info = $_[0]->recv;	668	my @info = $_[0]->recv;
480	});	669	});
…		…
498	immediately from within send.	687	immediately from within send.
499		688
500	Any arguments passed to the C<send> call will be returned by all	689	Any arguments passed to the C<send> call will be returned by all
501	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
502		691
503	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
504	(as a code reference). Calling them directly is the same as calling	693	they were a code reference). Calling them directly is the same as calling
505	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
506	overloading, so as tempting as it may be, passing a condition variable
507	instead of a callback does not work. Both the pure perl and EV loops
508	support overloading, however, as well as all functions that use perl to
509	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
510	example).
511		695
512	=item $cv->croak ($error)	696	=item $cv->croak ($error)
513		697
514	Similar to send, but causes all call's to C<< ->recv >> to invoke	698	Similar to send, but causes all calls to C<< ->recv >> to invoke
515	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
516		700
517	This can be used to signal any errors to the condition variable	701	This can be used to signal any errors to the condition variable
518	user/consumer.	702	user/consumer. Doing it this way instead of calling C<croak> directly
		703	delays the error detection, but has the overwhelming advantage that it
		704	diagnoses the error at the place where the result is expected, and not
		705	deep in some event callback with no connection to the actual code causing
		706	the problem.
519		707
520	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
521		709
522	=item $cv->end	710	=item $cv->end
523
524	These two methods are EXPERIMENTAL and MIGHT CHANGE.
525		711
526	These two methods can be used to combine many transactions/events into	712	These two methods can be used to combine many transactions/events into
527	one. For example, a function that pings many hosts in parallel might want	713	one. For example, a function that pings many hosts in parallel might want
528	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
529		715
530	Every call to C<< ->begin >> will increment a counter, and every call to	716	Every call to C<< ->begin >> will increment a counter, and every call to
531	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	717	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
532	>>, the (last) callback passed to C<begin> will be executed. That callback	718	>>, the (last) callback passed to C<begin> will be executed, passing the
533	is I<supposed> to call C<< ->send >>, but that is not required. If no	719	condvar as first argument. That callback is I<supposed> to call C<< ->send
534	callback was set, C<send> will be called without any arguments.	720	>>, but that is not required. If no group callback was set, C<send> will
		721	be called without any arguments.
535		722
536	Let's clarify this with the ping example:	723	You can think of C<< $cv->send >> giving you an OR condition (one call
		724	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		725	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		726
		727	Let's start with a simple example: you have two I/O watchers (for example,
		728	STDOUT and STDERR for a program), and you want to wait for both streams to
		729	close before activating a condvar:
537		730
538	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
539		732
		733	$cv->begin; # first watcher
		734	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		735	defined sysread $fh1, my $buf, 4096
		736	or $cv->end;
		737	});
		738
		739	$cv->begin; # second watcher
		740	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		741	defined sysread $fh2, my $buf, 4096
		742	or $cv->end;
		743	});
		744
		745	$cv->recv;
		746
		747	This works because for every event source (EOF on file handle), there is
		748	one call to C<begin>, so the condvar waits for all calls to C<end> before
		749	sending.
		750
		751	The ping example mentioned above is slightly more complicated, as the
		752	there are results to be passwd back, and the number of tasks that are
		753	begun can potentially be zero:
		754
		755	my $cv = AnyEvent->condvar;
		756
540	my %result;	757	my %result;
541	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
542		759
543	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
544	$cv->begin;	761	$cv->begin;
545	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
546	$result{$host} = ...;	763	$result{$host} = ...;
…		…
561	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
562	to be called once the counter reaches C<0>, and second, it ensures that	779	to be called once the counter reaches C<0>, and second, it ensures that
563	C<send> is called even when C<no> hosts are being pinged (the loop	780	C<send> is called even when C<no> hosts are being pinged (the loop
564	doesn't execute once).	781	doesn't execute once).
565		782
566	This is the general pattern when you "fan out" into multiple subrequests:	783	This is the general pattern when you "fan out" into multiple (but
567	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	784	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
568	is called at least once, and then, for each subrequest you start, call	785	the callback and ensure C<end> is called at least once, and then, for each
569	C<begin> and for each subrequest you finish, call C<end>.	786	subrequest you start, call C<begin> and for each subrequest you finish,
		787	call C<end>.
570		788
571	=back	789	=back
572		790
573	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
574		792
…		…
578	=over 4	796	=over 4
579		797
580	=item $cv->recv	798	=item $cv->recv
581		799
582	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
583	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
584	normally.	802	normally.
585		803
586	You can only wait once on a condition - additional calls are valid but	804	You can only wait once on a condition - additional calls are valid but
587	will return immediately.	805	will return immediately.
588		806
…		…
590	function will call C<croak>.	808	function will call C<croak>.
591		809
592	In list context, all parameters passed to C<send> will be returned,	810	In list context, all parameters passed to C<send> will be returned,
593	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
594		812
		813	Note that doing a blocking wait in a callback is not supported by any
		814	event loop, that is, recursive invocation of a blocking C<< ->recv
		815	>> is not allowed, and the C<recv> call will C<croak> if such a
		816	condition is detected. This condition can be slightly loosened by using
		817	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		818	any thread that doesn't run the event loop itself.
		819
595	Not all event models support a blocking wait - some die in that case	820	Not all event models support a blocking wait - some die in that case
596	(programs might want to do that to stay interactive), so I<if you are	821	(programs might want to do that to stay interactive), so I<if you are
597	using this from a module, never require a blocking wait>, but let the	822	using this from a module, never require a blocking wait>. Instead, let the
598	caller decide whether the call will block or not (for example, by coupling	823	caller decide whether the call will block or not (for example, by coupling
599	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
600	callbacks so the caller knows that getting the result will not block,	825	callbacks so the caller knows that getting the result will not block,
601	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
602		827
603	Another reason I<never> to C<< ->recv >> in a module is that you cannot
604	sensibly have two C<< ->recv >>'s in parallel, as that would require
605	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
606	can supply.
607
608	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
609	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
610	versions and also integrates coroutines into AnyEvent, making blocking
611	C<< ->recv >> calls perfectly safe as long as they are done from another
612	coroutine (one that doesn't run the event loop).
613
614	You can ensure that C<< -recv >> never blocks by setting a callback and	828	You can ensure that C<< ->recv >> never blocks by setting a callback and
615	only calling C<< ->recv >> from within that callback (or at a later	829	only calling C<< ->recv >> from within that callback (or at a later
616	time). This will work even when the event loop does not support blocking	830	time). This will work even when the event loop does not support blocking
617	waits otherwise.	831	waits otherwise.
618		832
619	=item $bool = $cv->ready	833	=item $bool = $cv->ready
…		…
625		839
626	This is a mutator function that returns the callback set and optionally	840	This is a mutator function that returns the callback set and optionally
627	replaces it before doing so.	841	replaces it before doing so.
628		842
629	The callback will be called when the condition becomes "true", i.e. when	843	The callback will be called when the condition becomes "true", i.e. when
630	C<send> or C<croak> are called, with the only argument being the condition	844	C<send> or C<croak> are called, with the only argument being the
631	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
632	is guaranteed not to block.	846	callback is called immediately when it is set. Calling C<recv> inside
		847	the callback or at any later time is guaranteed not to block.
633		848
634	=back	849	=back
635		850
		851	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		852
		853	The available backend classes are (every class has its own manpage):
		854
		855	=over 4
		856
		857	=item Backends that are autoprobed when no other event loop can be found.
		858
		859	EV is the preferred backend when no other event loop seems to be in
		860	use. If EV is not installed, then AnyEvent will fall back to its own
		861	pure-perl implementation, which is available everywhere as it comes with
		862	AnyEvent itself.
		863
		864	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		865	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		866
		867	=item Backends that are transparently being picked up when they are used.
		868
		869	These will be used if they are already loaded when the first watcher
		870	is created, in which case it is assumed that the application is using
		871	them. This means that AnyEvent will automatically pick the right backend
		872	when the main program loads an event module before anything starts to
		873	create watchers. Nothing special needs to be done by the main program.
		874
		875	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		876	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		877	AnyEvent::Impl::Tk based on Tk, very broken.
		878	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		879	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		880	AnyEvent::Impl::Irssi used when running within irssi.
		881	AnyEvent::Impl::IOAsync based on IO::Async.
		882
		883	=item Backends with special needs.
		884
		885	Qt requires the Qt::Application to be instantiated first, but will
		886	otherwise be picked up automatically. As long as the main program
		887	instantiates the application before any AnyEvent watchers are created,
		888	everything should just work.
		889
		890	AnyEvent::Impl::Qt based on Qt.
		891
		892	=item Event loops that are indirectly supported via other backends.
		893
		894	Some event loops can be supported via other modules:
		895
		896	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		897
		898	B<WxWidgets> has no support for watching file handles. However, you can
		899	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		900	polls 20 times per second, which was considered to be too horrible to even
		901	consider for AnyEvent.
		902
		903	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		904	backend, so it can be supported through POE.
		905
		906	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		907	load L<POE> when detecting them, in the hope that POE will pick them up,
		908	in which case everything will be automatic.
		909
		910	=back
		911
636	=head1 GLOBAL VARIABLES AND FUNCTIONS	912	=head1 GLOBAL VARIABLES AND FUNCTIONS
637		913
		914	These are not normally required to use AnyEvent, but can be useful to
		915	write AnyEvent extension modules.
		916
638	=over 4	917	=over 4
639		918
640	=item $AnyEvent::MODEL	919	=item $AnyEvent::MODEL
641		920
642	Contains C<undef> until the first watcher is being created. Then it	921	Contains C<undef> until the first watcher is being created, before the
		922	backend has been autodetected.
		923
643	contains the event model that is being used, which is the name of the	924	Afterwards it contains the event model that is being used, which is the
644	Perl class implementing the model. This class is usually one of the	925	name of the Perl class implementing the model. This class is usually one
645	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	926	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
646	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	927	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
647		928	will be C<urxvt::anyevent>).
648	The known classes so far are:
649
650	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
651	AnyEvent::Impl::Event based on Event, second best choice.
652	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
653	AnyEvent::Impl::Glib based on Glib, third-best choice.
654	AnyEvent::Impl::Tk based on Tk, very bad choice.
655	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
656	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
657	AnyEvent::Impl::POE based on POE, not generic enough for full support.
658
659	There is no support for WxWidgets, as WxWidgets has no support for
660	watching file handles. However, you can use WxWidgets through the
661	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
662	second, which was considered to be too horrible to even consider for
663	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
664	it's adaptor.
665
666	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
667	autodetecting them.
668		929
669	=item AnyEvent::detect	930	=item AnyEvent::detect
670		931
671	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	932	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
672	if necessary. You should only call this function right before you would	933	if necessary. You should only call this function right before you would
673	have created an AnyEvent watcher anyway, that is, as late as possible at	934	have created an AnyEvent watcher anyway, that is, as late as possible at
674	runtime.	935	runtime, and not e.g. during initialisation of your module.
		936
		937	If you need to do some initialisation before AnyEvent watchers are
		938	created, use C<post_detect>.
675		939
676	=item $guard = AnyEvent::post_detect { BLOCK }	940	=item $guard = AnyEvent::post_detect { BLOCK }
677		941
678	Arranges for the code block to be executed as soon as the event model is	942	Arranges for the code block to be executed as soon as the event model is
679	autodetected (or immediately if this has already happened).	943	autodetected (or immediately if that has already happened).
		944
		945	The block will be executed I<after> the actual backend has been detected
		946	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		947	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		948	other initialisations - see the sources of L<AnyEvent::Strict> or
		949	L<AnyEvent::AIO> to see how this is used.
		950
		951	The most common usage is to create some global watchers, without forcing
		952	event module detection too early, for example, L<AnyEvent::AIO> creates
		953	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		954	avoid autodetecting the event module at load time.
680		955
681	If called in scalar or list context, then it creates and returns an object	956	If called in scalar or list context, then it creates and returns an object
682	that automatically removes the callback again when it is destroyed. See	957	that automatically removes the callback again when it is destroyed (or
		958	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
683	L<Coro::BDB> for a case where this is useful.	959	a case where this is useful.
		960
		961	Example: Create a watcher for the IO::AIO module and store it in
		962	C<$WATCHER>, but do so only do so after the event loop is initialised.
		963
		964	our WATCHER;
		965
		966	my $guard = AnyEvent::post_detect {
		967	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		968	};
		969
		970	# the ||= is important in case post_detect immediately runs the block,
		971	# as to not clobber the newly-created watcher. assigning both watcher and
		972	# post_detect guard to the same variable has the advantage of users being
		973	# able to just C<undef $WATCHER> if the watcher causes them grief.
		974
		975	$WATCHER ||= $guard;
684		976
685	=item @AnyEvent::post_detect	977	=item @AnyEvent::post_detect
686		978
687	If there are any code references in this array (you can C<push> to it	979	If there are any code references in this array (you can C<push> to it
688	before or after loading AnyEvent), then they will called directly after	980	before or after loading AnyEvent), then they will be called directly
689	the event loop has been chosen.	981	after the event loop has been chosen.
690		982
691	You should check C<$AnyEvent::MODEL> before adding to this array, though:	983	You should check C<$AnyEvent::MODEL> before adding to this array, though:
692	if it contains a true value then the event loop has already been detected,	984	if it is defined then the event loop has already been detected, and the
693	and the array will be ignored.	985	array will be ignored.
694		986
695	Best use C<AnyEvent::post_detect { BLOCK }> instead.	987	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		988	it, as it takes care of these details.
		989
		990	This variable is mainly useful for modules that can do something useful
		991	when AnyEvent is used and thus want to know when it is initialised, but do
		992	not need to even load it by default. This array provides the means to hook
		993	into AnyEvent passively, without loading it.
		994
		995	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		996	together, you could put this into Coro (this is the actual code used by
		997	Coro to accomplish this):
		998
		999	if (defined $AnyEvent::MODEL) {
		1000	# AnyEvent already initialised, so load Coro::AnyEvent
		1001	require Coro::AnyEvent;
		1002	} else {
		1003	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1004	# as soon as it is
		1005	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1006	}
696		1007
697	=back	1008	=back
698		1009
699	=head1 WHAT TO DO IN A MODULE	1010	=head1 WHAT TO DO IN A MODULE
700		1011
…		…
711	because it will stall the whole program, and the whole point of using	1022	because it will stall the whole program, and the whole point of using
712	events is to stay interactive.	1023	events is to stay interactive.
713		1024
714	It is fine, however, to call C<< ->recv >> when the user of your module	1025	It is fine, however, to call C<< ->recv >> when the user of your module
715	requests it (i.e. if you create a http request object ad have a method	1026	requests it (i.e. if you create a http request object ad have a method
716	called C<results> that returns the results, it should call C<< ->recv >>	1027	called C<results> that returns the results, it may call C<< ->recv >>
717	freely, as the user of your module knows what she is doing. always).	1028	freely, as the user of your module knows what she is doing. Always).
718		1029
719	=head1 WHAT TO DO IN THE MAIN PROGRAM	1030	=head1 WHAT TO DO IN THE MAIN PROGRAM
720		1031
721	There will always be a single main program - the only place that should	1032	There will always be a single main program - the only place that should
722	dictate which event model to use.	1033	dictate which event model to use.
723		1034
724	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1035	If the program is not event-based, it need not do anything special, even
725	do anything special (it does not need to be event-based) and let AnyEvent	1036	when it depends on a module that uses an AnyEvent. If the program itself
726	decide which implementation to chose if some module relies on it.	1037	uses AnyEvent, but does not care which event loop is used, all it needs
		1038	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1039	available loop implementation.
727		1040
728	If the main program relies on a specific event model - for example, in	1041	If the main program relies on a specific event model - for example, in
729	Gtk2 programs you have to rely on the Glib module - you should load the	1042	Gtk2 programs you have to rely on the Glib module - you should load the
730	event module before loading AnyEvent or any module that uses it: generally	1043	event module before loading AnyEvent or any module that uses it: generally
731	speaking, you should load it as early as possible. The reason is that	1044	speaking, you should load it as early as possible. The reason is that
732	modules might create watchers when they are loaded, and AnyEvent will	1045	modules might create watchers when they are loaded, and AnyEvent will
733	decide on the event model to use as soon as it creates watchers, and it	1046	decide on the event model to use as soon as it creates watchers, and it
734	might chose the wrong one unless you load the correct one yourself.	1047	might choose the wrong one unless you load the correct one yourself.
735		1048
736	You can chose to use a pure-perl implementation by loading the	1049	You can chose to use a pure-perl implementation by loading the
737	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1050	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
738	everywhere, but letting AnyEvent chose the model is generally better.	1051	everywhere, but letting AnyEvent chose the model is generally better.
739		1052
…		…
755		1068
756		1069
757	=head1 OTHER MODULES	1070	=head1 OTHER MODULES
758		1071
759	The following is a non-exhaustive list of additional modules that use	1072	The following is a non-exhaustive list of additional modules that use
760	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1073	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
761	in the same program. Some of the modules come with AnyEvent, some are	1074	modules and other event loops in the same program. Some of the modules
762	available via CPAN.	1075	come as part of AnyEvent, the others are available via CPAN.
763		1076
764	=over 4	1077	=over 4
765		1078
766	=item L<AnyEvent::Util>	1079	=item L<AnyEvent::Util>
767		1080
768	Contains various utility functions that replace often-used but blocking	1081	Contains various utility functions that replace often-used blocking
769	functions such as C<inet_aton> by event-/callback-based versions.	1082	functions such as C<inet_aton> with event/callback-based versions.
770		1083
771	=item L<AnyEvent::Socket>	1084	=item L<AnyEvent::Socket>
772		1085
773	Provides various utility functions for (internet protocol) sockets,	1086	Provides various utility functions for (internet protocol) sockets,
774	addresses and name resolution. Also functions to create non-blocking tcp	1087	addresses and name resolution. Also functions to create non-blocking tcp
…		…
776		1089
777	=item L<AnyEvent::Handle>	1090	=item L<AnyEvent::Handle>
778		1091
779	Provide read and write buffers, manages watchers for reads and writes,	1092	Provide read and write buffers, manages watchers for reads and writes,
780	supports raw and formatted I/O, I/O queued and fully transparent and	1093	supports raw and formatted I/O, I/O queued and fully transparent and
781	non-blocking SSL/TLS.	1094	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
782		1095
783	=item L<AnyEvent::DNS>	1096	=item L<AnyEvent::DNS>
784		1097
785	Provides rich asynchronous DNS resolver capabilities.	1098	Provides rich asynchronous DNS resolver capabilities.
786		1099
		1100	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1101
		1102	Implement event-based interfaces to the protocols of the same name (for
		1103	the curious, IGS is the International Go Server and FCP is the Freenet
		1104	Client Protocol).
		1105
		1106	=item L<AnyEvent::Handle::UDP>
		1107
		1108	Here be danger!
		1109
		1110	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1111	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1112	its use of a stream-based API with a protocol that isn't streamable, that
		1113	the only way to improve it is to delete it.
		1114
		1115	It features data corruption (but typically only under load) and general
		1116	confusion. On top, the author is not only clueless about UDP but also
		1117	fact-resistant - some gems of his understanding: "connect doesn't work
		1118	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1119	packets", "I don't need to implement proper error checking as UDP doesn't
		1120	support error checking" and so on - he doesn't even understand what's
		1121	wrong with his module when it is explained to him.
		1122
787	=item L<AnyEvent::HTTP>	1123	=item L<AnyEvent::DBI>
788		1124
789	A simple-to-use HTTP library that is capable of making a lot of concurrent	1125	Executes L<DBI> requests asynchronously in a proxy process for you,
790	HTTP requests.	1126	notifying you in an event-based way when the operation is finished.
		1127
		1128	=item L<AnyEvent::AIO>
		1129
		1130	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1131	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1132	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1133	file I/O, and much more.
791		1134
792	=item L<AnyEvent::HTTPD>	1135	=item L<AnyEvent::HTTPD>
793		1136
794	Provides a simple web application server framework.	1137	A simple embedded webserver.
795		1138
796	=item L<AnyEvent::FastPing>	1139	=item L<AnyEvent::FastPing>
797		1140
798	The fastest ping in the west.	1141	The fastest ping in the west.
799		1142
800	=item L<AnyEvent::DBI>
801
802	Executes L<DBI> requests asynchronously in a proxy process.
803
804	=item L<AnyEvent::AIO>
805
806	Truly asynchronous I/O, should be in the toolbox of every event
807	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
808	together.
809
810	=item L<AnyEvent::BDB>
811
812	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
813	L<BDB> and AnyEvent together.
814
815	=item L<AnyEvent::GPSD>
816
817	A non-blocking interface to gpsd, a daemon delivering GPS information.
818
819	=item L<AnyEvent::IGS>
820
821	A non-blocking interface to the Internet Go Server protocol (used by
822	L<App::IGS>).
823
824	=item L<Net::IRC3>
825
826	AnyEvent based IRC client module family.
827
828	=item L<Net::XMPP2>
829
830	AnyEvent based XMPP (Jabber protocol) module family.
831
832	=item L<Net::FCP>
833
834	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
835	of AnyEvent.
836
837	=item L<Event::ExecFlow>
838
839	High level API for event-based execution flow control.
840
841	=item L<Coro>	1143	=item L<Coro>
842		1144
843	Has special support for AnyEvent via L<Coro::AnyEvent>.	1145	Has special support for AnyEvent via L<Coro::AnyEvent>.
844		1146
845	=item L<IO::Lambda>
846
847	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
848
849	=back	1147	=back
850		1148
851	=cut	1149	=cut
852		1150
853	package AnyEvent;	1151	package AnyEvent;
854		1152
855	no warnings;	1153	# basically a tuned-down version of common::sense
856	use strict;	1154	sub common_sense {
		1155	# from common:.sense 3.3
		1156	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf3\x0f\xc0\xf0\xfc\x33\x00";
		1157	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1158	$^H |= 0x00000600;
		1159	}
857		1160
		1161	BEGIN { AnyEvent::common_sense }
		1162
858	use Carp;	1163	use Carp ();
859		1164
860	our $VERSION = 4.22;	1165	our $VERSION = '5.29';
861	our $MODEL;	1166	our $MODEL;
862		1167
863	our $AUTOLOAD;	1168	our $AUTOLOAD;
864	our @ISA;	1169	our @ISA;
865		1170
866	our @REGISTRY;	1171	our @REGISTRY;
867		1172
868	our $WIN32;	1173	our $VERBOSE;
869		1174
870	BEGIN {	1175	BEGIN {
871	my $win32 = ! ! ($^O =~ /mswin32/i);	1176	require "AnyEvent/constants.pl";
872	eval "sub WIN32(){ $win32 }";
873	}
874		1177
		1178	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1179
		1180	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1181	if ${^TAINT};
		1182
875	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1183	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1184
		1185	}
		1186
		1187	our $MAX_SIGNAL_LATENCY = 10;
876		1188
877	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1189	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
878		1190
879	{	1191	{
880	my $idx;	1192	my $idx;
…		…
882	for reverse split /\s*,\s*/,	1194	for reverse split /\s*,\s*/,
883	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1195	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
884	}	1196	}
885		1197
886	my @models = (	1198	my @models = (
887	[EV:: => AnyEvent::Impl::EV::],	1199	[EV:: => AnyEvent::Impl::EV:: , 1],
888	[Event:: => AnyEvent::Impl::Event::],
889	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1200	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
890	# everything below here will not be autoprobed	1201	# everything below here will not (normally) be autoprobed
891	# as the pureperl backend should work everywhere	1202	# as the pureperl backend should work everywhere
892	# and is usually faster	1203	# and is usually faster
		1204	[Event:: => AnyEvent::Impl::Event::, 1],
		1205	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1206	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1207	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
893	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1208	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
894	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
895	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
896	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1209	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
897	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1210	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
898	[Wx:: => AnyEvent::Impl::POE::],	1211	[Wx:: => AnyEvent::Impl::POE::],
899	[Prima:: => AnyEvent::Impl::POE::],	1212	[Prima:: => AnyEvent::Impl::POE::],
		1213	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::],
900	);	1214	);
901		1215
902	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1216	our %method = map +($_ => 1),
		1217	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
903		1218
904	our @post_detect;	1219	our @post_detect;
905		1220
906	sub post_detect(&) {	1221	sub post_detect(&) {
907	my ($cb) = @_;	1222	my ($cb) = @_;
908		1223
909	if ($MODEL) {
910	$cb->();
911
912	1
913	} else {
914	push @post_detect, $cb;	1224	push @post_detect, $cb;
915		1225
916	defined wantarray	1226	defined wantarray
917	? bless \$cb, "AnyEvent::Util::PostDetect"	1227	? bless \$cb, "AnyEvent::Util::postdetect"
918	: ()	1228	: ()
		1229	}
		1230
		1231	sub AnyEvent::Util::postdetect::DESTROY {
		1232	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1233	}
		1234
		1235	sub detect() {
		1236	# free some memory
		1237	*detect = sub () { $MODEL };
		1238
		1239	local $!; # for good measure
		1240	local $SIG{__DIE__};
		1241
		1242	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1243	my $model = "AnyEvent::Impl::$1";
		1244	if (eval "require $model") {
		1245	$MODEL = $model;
		1246	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
		1247	} else {
		1248	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
		1249	}
919	}	1250	}
920	}
921		1251
922	sub AnyEvent::Util::PostDetect::DESTROY {	1252	# check for already loaded models
923	@post_detect = grep $_ != ${$_[0]}, @post_detect;
924	}
925
926	sub detect() {
927	unless ($MODEL) {	1253	unless ($MODEL) {
928	no strict 'refs';	1254	for (@REGISTRY, @models) {
929	local $SIG{__DIE__};	1255	my ($package, $model) = @$_;
930		1256	if (${"$package\::VERSION"} > 0) {
931	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
932	my $model = "AnyEvent::Impl::$1";
933	if (eval "require $model") {	1257	if (eval "require $model") {
934	$MODEL = $model;	1258	$MODEL = $model;
935	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1259	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
936	} else {	1260	last;
937	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1261	}
938	}	1262	}
939	}	1263	}
940		1264
941	# check for already loaded models
942	unless ($MODEL) {	1265	unless ($MODEL) {
		1266	# try to autoload a model
943	for (@REGISTRY, @models) {	1267	for (@REGISTRY, @models) {
944	my ($package, $model) = @$_;	1268	my ($package, $model, $autoload) = @$_;
		1269	if (
		1270	$autoload
		1271	and eval "require $package"
945	if (${"$package\::VERSION"} > 0) {	1272	and ${"$package\::VERSION"} > 0
946	if (eval "require $model") {	1273	and eval "require $model"
		1274	) {
947	$MODEL = $model;	1275	$MODEL = $model;
948	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1276	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
949	last;	1277	last;
950	}
951	}	1278	}
952	}	1279	}
953		1280
954	unless ($MODEL) {
955	# try to load a model
956
957	for (@REGISTRY, @models) {
958	my ($package, $model) = @$_;
959	if (eval "require $package"
960	and ${"$package\::VERSION"} > 0
961	and eval "require $model") {
962	$MODEL = $model;
963	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
964	last;
965	}
966	}
967
968	$MODEL	1281	$MODEL
969	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1282	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
970	}
971	}	1283	}
972
973	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
974
975	unshift @ISA, $MODEL;
976
977	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
978
979	(shift @post_detect)->() while @post_detect;
980	}	1284	}
		1285
		1286	@models = (); # free probe data
		1287
		1288	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1289	unshift @ISA, $MODEL;
		1290
		1291	# now nuke some methods that are overridden by the backend.
		1292	# SUPER is not allowed.
		1293	for (qw(time signal child idle)) {
		1294	undef &{"AnyEvent::Base::$_"}
		1295	if defined &{"$MODEL\::$_"};
		1296	}
		1297
		1298	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1299	eval { require AnyEvent::Strict };
		1300	warn "AnyEvent: cannot load AnyEvent::Strict: $@"
		1301	if $@ && $VERBOSE;
		1302	}
		1303
		1304	(shift @post_detect)->() while @post_detect;
		1305
		1306	*post_detect = sub(&) {
		1307	shift->();
		1308
		1309	undef
		1310	};
981		1311
982	$MODEL	1312	$MODEL
983	}	1313	}
984		1314
985	sub AUTOLOAD {	1315	sub AUTOLOAD {
986	(my $func = $AUTOLOAD) =~ s/.*://;	1316	(my $func = $AUTOLOAD) =~ s/.*://;
987		1317
988	$method{$func}	1318	$method{$func}
989	or croak "$func: not a valid method for AnyEvent objects";	1319	or Carp::croak "$func: not a valid AnyEvent class method";
990		1320
991	detect unless $MODEL;	1321	detect;
992		1322
993	my $class = shift;	1323	my $class = shift;
994	$class->$func (@_);	1324	$class->$func (@_);
995	}	1325	}
996		1326
997	# utility function to dup a filehandle. this is used by many backends	1327	# utility function to dup a filehandle. this is used by many backends
998	# to support binding more than one watcher per filehandle (they usually	1328	# to support binding more than one watcher per filehandle (they usually
999	# allow only one watcher per fd, so we dup it to get a different one).	1329	# allow only one watcher per fd, so we dup it to get a different one).
1000	sub _dupfh($$$$) {	1330	sub _dupfh($$;$$) {
1001	my ($poll, $fh, $r, $w) = @_;	1331	my ($poll, $fh, $r, $w) = @_;
1002		1332
1003	require Fcntl;
1004
1005	# cygwin requires the fh mode to be matching, unix doesn't	1333	# cygwin requires the fh mode to be matching, unix doesn't
1006	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1334	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1007	: $poll eq "w" ? ($w, ">")
1008	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1009		1335
1010	open my $fh2, "$mode&" . fileno $fh	1336	open my $fh2, $mode, $fh
1011	or die "cannot dup() filehandle: $!";	1337	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1012		1338
1013	# we assume CLOEXEC is already set by perl in all important cases	1339	# we assume CLOEXEC is already set by perl in all important cases
1014		1340
1015	($fh2, $rw)	1341	($fh2, $rw)
1016	}	1342	}
1017		1343
		1344	=head1 SIMPLIFIED AE API
		1345
		1346	Starting with version 5.0, AnyEvent officially supports a second, much
		1347	simpler, API that is designed to reduce the calling, typing and memory
		1348	overhead by using function call syntax and a fixed number of parameters.
		1349
		1350	See the L<AE> manpage for details.
		1351
		1352	=cut
		1353
		1354	package AE;
		1355
		1356	our $VERSION = $AnyEvent::VERSION;
		1357
		1358	# fall back to the main API by default - backends and AnyEvent::Base
		1359	# implementations can overwrite these.
		1360
		1361	sub io($$$) {
		1362	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1363	}
		1364
		1365	sub timer($$$) {
		1366	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1367	}
		1368
		1369	sub signal($$) {
		1370	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1371	}
		1372
		1373	sub child($$) {
		1374	AnyEvent->child (pid => $_[0], cb => $_[1])
		1375	}
		1376
		1377	sub idle($) {
		1378	AnyEvent->idle (cb => $_[0])
		1379	}
		1380
		1381	sub cv(;&) {
		1382	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1383	}
		1384
		1385	sub now() {
		1386	AnyEvent->now
		1387	}
		1388
		1389	sub now_update() {
		1390	AnyEvent->now_update
		1391	}
		1392
		1393	sub time() {
		1394	AnyEvent->time
		1395	}
		1396
1018	package AnyEvent::Base;	1397	package AnyEvent::Base;
1019		1398
1020	# default implementation for now and time	1399	# default implementations for many methods
1021		1400
1022	use Time::HiRes ();	1401	sub time {
		1402	eval q{ # poor man's autoloading {}
		1403	# probe for availability of Time::HiRes
		1404	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1405	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1406	*AE::time = \&Time::HiRes::time;
		1407	# if (eval "use POSIX (); (POSIX::times())...
		1408	} else {
		1409	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1410	*AE::time = sub (){ time }; # epic fail
		1411	}
1023		1412
1024	sub time { Time::HiRes::time }	1413	*time = sub { AE::time }; # different prototypes
1025	sub now { Time::HiRes::time }	1414	};
		1415	die if $@;
		1416
		1417	&time
		1418	}
		1419
		1420	*now = \&time;
		1421
		1422	sub now_update { }
1026		1423
1027	# default implementation for ->condvar	1424	# default implementation for ->condvar
1028		1425
1029	sub condvar {	1426	sub condvar {
		1427	eval q{ # poor man's autoloading {}
		1428	*condvar = sub {
1030	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1429	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1430	};
		1431
		1432	*AE::cv = sub (;&) {
		1433	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1434	};
		1435	};
		1436	die if $@;
		1437
		1438	&condvar
1031	}	1439	}
1032		1440
1033	# default implementation for ->signal	1441	# default implementation for ->signal
1034		1442
1035	our %SIG_CB;	1443	our $HAVE_ASYNC_INTERRUPT;
		1444
		1445	sub _have_async_interrupt() {
		1446	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1447	&& eval "use Async::Interrupt 1.02 (); 1")
		1448	unless defined $HAVE_ASYNC_INTERRUPT;
		1449
		1450	$HAVE_ASYNC_INTERRUPT
		1451	}
		1452
		1453	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1454	our (%SIG_ASY, %SIG_ASY_W);
		1455	our ($SIG_COUNT, $SIG_TW);
		1456
		1457	# install a dummy wakeup watcher to reduce signal catching latency
		1458	# used by Impls
		1459	sub _sig_add() {
		1460	unless ($SIG_COUNT++) {
		1461	# try to align timer on a full-second boundary, if possible
		1462	my $NOW = AE::now;
		1463
		1464	$SIG_TW = AE::timer
		1465	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1466	$MAX_SIGNAL_LATENCY,
		1467	sub { } # just for the PERL_ASYNC_CHECK
		1468	;
		1469	}
		1470	}
		1471
		1472	sub _sig_del {
		1473	undef $SIG_TW
		1474	unless --$SIG_COUNT;
		1475	}
		1476
		1477	our $_sig_name_init; $_sig_name_init = sub {
		1478	eval q{ # poor man's autoloading {}
		1479	undef $_sig_name_init;
		1480
		1481	if (_have_async_interrupt) {
		1482	*sig2num = \&Async::Interrupt::sig2num;
		1483	*sig2name = \&Async::Interrupt::sig2name;
		1484	} else {
		1485	require Config;
		1486
		1487	my %signame2num;
		1488	@signame2num{ split ' ', $Config::Config{sig_name} }
		1489	= split ' ', $Config::Config{sig_num};
		1490
		1491	my @signum2name;
		1492	@signum2name[values %signame2num] = keys %signame2num;
		1493
		1494	*sig2num = sub($) {
		1495	$_[0] > 0 ? shift : $signame2num{+shift}
		1496	};
		1497	*sig2name = sub ($) {
		1498	$_[0] > 0 ? $signum2name[+shift] : shift
		1499	};
		1500	}
		1501	};
		1502	die if $@;
		1503	};
		1504
		1505	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1506	sub sig2name($) { &$_sig_name_init; &sig2name }
1036		1507
1037	sub signal {	1508	sub signal {
		1509	eval q{ # poor man's autoloading {}
		1510	# probe for availability of Async::Interrupt
		1511	if (_have_async_interrupt) {
		1512	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1513
		1514	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1515	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1516
		1517	} else {
		1518	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1519
		1520	if (AnyEvent::WIN32) {
		1521	require AnyEvent::Util;
		1522
		1523	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1524	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1525	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1526	} else {
		1527	pipe $SIGPIPE_R, $SIGPIPE_W;
		1528	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1529	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1530
		1531	# not strictly required, as $^F is normally 2, but let's make sure...
		1532	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1533	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1534	}
		1535
		1536	$SIGPIPE_R
		1537	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1538
		1539	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1540	}
		1541
		1542	*signal = $HAVE_ASYNC_INTERRUPT
		1543	? sub {
1038	my (undef, %arg) = @_;	1544	my (undef, %arg) = @_;
1039		1545
		1546	# async::interrupt
1040	my $signal = uc $arg{signal}	1547	my $signal = sig2num $arg{signal};
1041	or Carp::croak "required option 'signal' is missing";
1042
1043	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1548	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1549
		1550	$SIG_ASY{$signal} ||= new Async::Interrupt
		1551	cb => sub { undef $SIG_EV{$signal} },
		1552	signal => $signal,
		1553	pipe => [$SIGPIPE_R->filenos],
		1554	pipe_autodrain => 0,
		1555	;
		1556
		1557	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1558	}
		1559	: sub {
		1560	my (undef, %arg) = @_;
		1561
		1562	# pure perl
		1563	my $signal = sig2name $arg{signal};
		1564	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1565
1044	$SIG{$signal} ||= sub {	1566	$SIG{$signal} ||= sub {
		1567	local $!;
		1568	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1569	undef $SIG_EV{$signal};
		1570	};
		1571
		1572	# can't do signal processing without introducing races in pure perl,
		1573	# so limit the signal latency.
		1574	_sig_add;
		1575
		1576	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1577	}
		1578	;
		1579
		1580	*AnyEvent::Base::signal::DESTROY = sub {
		1581	my ($signal, $cb) = @{$_[0]};
		1582
		1583	_sig_del;
		1584
		1585	delete $SIG_CB{$signal}{$cb};
		1586
		1587	$HAVE_ASYNC_INTERRUPT
		1588	? delete $SIG_ASY{$signal}
		1589	: # delete doesn't work with older perls - they then
		1590	# print weird messages, or just unconditionally exit
		1591	# instead of getting the default action.
		1592	undef $SIG{$signal}
		1593	unless keys %{ $SIG_CB{$signal} };
		1594	};
		1595
		1596	*_signal_exec = sub {
		1597	$HAVE_ASYNC_INTERRUPT
		1598	? $SIGPIPE_R->drain
		1599	: sysread $SIGPIPE_R, (my $dummy), 9;
		1600
		1601	while (%SIG_EV) {
		1602	for (keys %SIG_EV) {
		1603	delete $SIG_EV{$_};
1045	$_->() for values %{ $SIG_CB{$signal} || {} };	1604	$_->() for values %{ $SIG_CB{$_} || {} };
		1605	}
		1606	}
		1607	};
1046	};	1608	};
		1609	die if $@;
1047		1610
1048	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1611	&signal
1049	}
1050
1051	sub AnyEvent::Base::Signal::DESTROY {
1052	my ($signal, $cb) = @{$_[0]};
1053
1054	delete $SIG_CB{$signal}{$cb};
1055
1056	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1057	}	1612	}
1058		1613
1059	# default implementation for ->child	1614	# default implementation for ->child
1060		1615
1061	our %PID_CB;	1616	our %PID_CB;
1062	our $CHLD_W;	1617	our $CHLD_W;
1063	our $CHLD_DELAY_W;	1618	our $CHLD_DELAY_W;
1064	our $PID_IDLE;
1065	our $WNOHANG;
1066		1619
1067	sub _child_wait {	1620	# used by many Impl's
1068	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1621	sub _emit_childstatus($$) {
		1622	my (undef, $rpid, $rstatus) = @_;
		1623
		1624	$_->($rpid, $rstatus)
1069	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1625	for values %{ $PID_CB{$rpid} || {} },
1070	(values %{ $PID_CB{0} || {} });	1626	values %{ $PID_CB{0} || {} };
1071	}
1072
1073	undef $PID_IDLE;
1074	}
1075
1076	sub _sigchld {
1077	# make sure we deliver these changes "synchronous" with the event loop.
1078	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1079	undef $CHLD_DELAY_W;
1080	&_child_wait;
1081	});
1082	}	1627	}
1083		1628
1084	sub child {	1629	sub child {
		1630	eval q{ # poor man's autoloading {}
		1631	*_sigchld = sub {
		1632	my $pid;
		1633
		1634	AnyEvent->_emit_childstatus ($pid, $?)
		1635	while ($pid = waitpid -1, WNOHANG) > 0;
		1636	};
		1637
		1638	*child = sub {
1085	my (undef, %arg) = @_;	1639	my (undef, %arg) = @_;
1086		1640
1087	defined (my $pid = $arg{pid} + 0)	1641	defined (my $pid = $arg{pid} + 0)
1088	or Carp::croak "required option 'pid' is missing";	1642	or Carp::croak "required option 'pid' is missing";
1089		1643
1090	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1644	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1091		1645
1092	unless ($WNOHANG) {
1093	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1094	}
1095
1096	unless ($CHLD_W) {	1646	unless ($CHLD_W) {
1097	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1647	$CHLD_W = AE::signal CHLD => \&_sigchld;
1098	# child could be a zombie already, so make at least one round	1648	# child could be a zombie already, so make at least one round
1099	&_sigchld;	1649	&_sigchld;
1100	}	1650	}
1101		1651
1102	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1652	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1103	}	1653	};
1104		1654
1105	sub AnyEvent::Base::Child::DESTROY {	1655	*AnyEvent::Base::child::DESTROY = sub {
1106	my ($pid, $cb) = @{$_[0]};	1656	my ($pid, $cb) = @{$_[0]};
1107		1657
1108	delete $PID_CB{$pid}{$cb};	1658	delete $PID_CB{$pid}{$cb};
1109	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1659	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1110		1660
1111	undef $CHLD_W unless keys %PID_CB;	1661	undef $CHLD_W unless keys %PID_CB;
		1662	};
		1663	};
		1664	die if $@;
		1665
		1666	&child
		1667	}
		1668
		1669	# idle emulation is done by simply using a timer, regardless
		1670	# of whether the process is idle or not, and not letting
		1671	# the callback use more than 50% of the time.
		1672	sub idle {
		1673	eval q{ # poor man's autoloading {}
		1674	*idle = sub {
		1675	my (undef, %arg) = @_;
		1676
		1677	my ($cb, $w, $rcb) = $arg{cb};
		1678
		1679	$rcb = sub {
		1680	if ($cb) {
		1681	$w = _time;
		1682	&$cb;
		1683	$w = _time - $w;
		1684
		1685	# never use more then 50% of the time for the idle watcher,
		1686	# within some limits
		1687	$w = 0.0001 if $w < 0.0001;
		1688	$w = 5 if $w > 5;
		1689
		1690	$w = AE::timer $w, 0, $rcb;
		1691	} else {
		1692	# clean up...
		1693	undef $w;
		1694	undef $rcb;
		1695	}
		1696	};
		1697
		1698	$w = AE::timer 0.05, 0, $rcb;
		1699
		1700	bless \\$cb, "AnyEvent::Base::idle"
		1701	};
		1702
		1703	*AnyEvent::Base::idle::DESTROY = sub {
		1704	undef $${$_[0]};
		1705	};
		1706	};
		1707	die if $@;
		1708
		1709	&idle
1112	}	1710	}
1113		1711
1114	package AnyEvent::CondVar;	1712	package AnyEvent::CondVar;
1115		1713
1116	our @ISA = AnyEvent::CondVar::Base::;	1714	our @ISA = AnyEvent::CondVar::Base::;
1117		1715
		1716	# only to be used for subclassing
		1717	sub new {
		1718	my $class = shift;
		1719	bless AnyEvent->condvar (@_), $class
		1720	}
		1721
1118	package AnyEvent::CondVar::Base;	1722	package AnyEvent::CondVar::Base;
1119		1723
1120	use overload	1724	#use overload
1121	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1725	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1122	fallback => 1;	1726	# fallback => 1;
		1727
		1728	# save 300+ kilobytes by dirtily hardcoding overloading
		1729	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1730	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1731	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1732	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1733
		1734	our $WAITING;
1123		1735
1124	sub _send {	1736	sub _send {
1125	# nop	1737	# nop
1126	}	1738	}
1127		1739
…		…
1140	sub ready {	1752	sub ready {
1141	$_[0]{_ae_sent}	1753	$_[0]{_ae_sent}
1142	}	1754	}
1143		1755
1144	sub _wait {	1756	sub _wait {
		1757	$WAITING
		1758	and !$_[0]{_ae_sent}
		1759	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1760
		1761	local $WAITING = 1;
1145	AnyEvent->one_event while !$_[0]{_ae_sent};	1762	AnyEvent->one_event while !$_[0]{_ae_sent};
1146	}	1763	}
1147		1764
1148	sub recv {	1765	sub recv {
1149	$_[0]->_wait;	1766	$_[0]->_wait;
…		…
1151	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1768	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1152	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1769	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1153	}	1770	}
1154		1771
1155	sub cb {	1772	sub cb {
1156	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1773	my $cv = shift;
		1774
		1775	@_
		1776	and $cv->{_ae_cb} = shift
		1777	and $cv->{_ae_sent}
		1778	and (delete $cv->{_ae_cb})->($cv);
		1779
1157	$_[0]{_ae_cb}	1780	$cv->{_ae_cb}
1158	}	1781	}
1159		1782
1160	sub begin {	1783	sub begin {
1161	++$_[0]{_ae_counter};	1784	++$_[0]{_ae_counter};
1162	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1785	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1168	}	1791	}
1169		1792
1170	# undocumented/compatibility with pre-3.4	1793	# undocumented/compatibility with pre-3.4
1171	*broadcast = \&send;	1794	*broadcast = \&send;
1172	*wait = \&_wait;	1795	*wait = \&_wait;
		1796
		1797	=head1 ERROR AND EXCEPTION HANDLING
		1798
		1799	In general, AnyEvent does not do any error handling - it relies on the
		1800	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1801	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1802	checking of all AnyEvent methods, however, which is highly useful during
		1803	development.
		1804
		1805	As for exception handling (i.e. runtime errors and exceptions thrown while
		1806	executing a callback), this is not only highly event-loop specific, but
		1807	also not in any way wrapped by this module, as this is the job of the main
		1808	program.
		1809
		1810	The pure perl event loop simply re-throws the exception (usually
		1811	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1812	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1813	so on.
		1814
		1815	=head1 ENVIRONMENT VARIABLES
		1816
		1817	The following environment variables are used by this module or its
		1818	submodules.
		1819
		1820	Note that AnyEvent will remove I<all> environment variables starting with
		1821	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1822	enabled.
		1823
		1824	=over 4
		1825
		1826	=item C<PERL_ANYEVENT_VERBOSE>
		1827
		1828	By default, AnyEvent will be completely silent except in fatal
		1829	conditions. You can set this environment variable to make AnyEvent more
		1830	talkative.
		1831
		1832	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1833	conditions, such as not being able to load the event model specified by
		1834	C<PERL_ANYEVENT_MODEL>.
		1835
		1836	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1837	model it chooses.
		1838
		1839	When set to C<8> or higher, then AnyEvent will report extra information on
		1840	which optional modules it loads and how it implements certain features.
		1841
		1842	=item C<PERL_ANYEVENT_STRICT>
		1843
		1844	AnyEvent does not do much argument checking by default, as thorough
		1845	argument checking is very costly. Setting this variable to a true value
		1846	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1847	check the arguments passed to most method calls. If it finds any problems,
		1848	it will croak.
		1849
		1850	In other words, enables "strict" mode.
		1851
		1852	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
		1853	>>, it is definitely recommended to keep it off in production. Keeping
		1854	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1855	can be very useful, however.
		1856
		1857	=item C<PERL_ANYEVENT_MODEL>
		1858
		1859	This can be used to specify the event model to be used by AnyEvent, before
		1860	auto detection and -probing kicks in. It must be a string consisting
		1861	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1862	and the resulting module name is loaded and if the load was successful,
		1863	used as event model. If it fails to load AnyEvent will proceed with
		1864	auto detection and -probing.
		1865
		1866	This functionality might change in future versions.
		1867
		1868	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1869	could start your program like this:
		1870
		1871	PERL_ANYEVENT_MODEL=Perl perl ...
		1872
		1873	=item C<PERL_ANYEVENT_PROTOCOLS>
		1874
		1875	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1876	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1877	of auto probing).
		1878
		1879	Must be set to a comma-separated list of protocols or address families,
		1880	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1881	used, and preference will be given to protocols mentioned earlier in the
		1882	list.
		1883
		1884	This variable can effectively be used for denial-of-service attacks
		1885	against local programs (e.g. when setuid), although the impact is likely
		1886	small, as the program has to handle conenction and other failures anyways.
		1887
		1888	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1889	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1890	- only support IPv4, never try to resolve or contact IPv6
		1891	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1892	IPv6, but prefer IPv6 over IPv4.
		1893
		1894	=item C<PERL_ANYEVENT_EDNS0>
		1895
		1896	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1897	for DNS. This extension is generally useful to reduce DNS traffic, but
		1898	some (broken) firewalls drop such DNS packets, which is why it is off by
		1899	default.
		1900
		1901	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1902	EDNS0 in its DNS requests.
		1903
		1904	=item C<PERL_ANYEVENT_MAX_FORKS>
		1905
		1906	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1907	will create in parallel.
		1908
		1909	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1910
		1911	The default value for the C<max_outstanding> parameter for the default DNS
		1912	resolver - this is the maximum number of parallel DNS requests that are
		1913	sent to the DNS server.
		1914
		1915	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1916
		1917	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1918	configuration) in the default resolver. When set to the empty string, no
		1919	default config will be used.
		1920
		1921	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1922
		1923	When neither C<ca_file> nor C<ca_path> was specified during
		1924	L<AnyEvent::TLS> context creation, and either of these environment
		1925	variables exist, they will be used to specify CA certificate locations
		1926	instead of a system-dependent default.
		1927
		1928	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1929
		1930	When these are set to C<1>, then the respective modules are not
		1931	loaded. Mostly good for testing AnyEvent itself.
		1932
		1933	=back
1173		1934
1174	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1935	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1175		1936
1176	This is an advanced topic that you do not normally need to use AnyEvent in	1937	This is an advanced topic that you do not normally need to use AnyEvent in
1177	a module. This section is only of use to event loop authors who want to	1938	a module. This section is only of use to event loop authors who want to
…		…
1211		1972
1212	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1973	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1213	condition variables: code blocking while waiting for a condition will	1974	condition variables: code blocking while waiting for a condition will
1214	C<die>. This still works with most modules/usages, and blocking calls must	1975	C<die>. This still works with most modules/usages, and blocking calls must
1215	not be done in an interactive application, so it makes sense.	1976	not be done in an interactive application, so it makes sense.
1216
1217	=head1 ENVIRONMENT VARIABLES
1218
1219	The following environment variables are used by this module:
1220
1221	=over 4
1222
1223	=item C<PERL_ANYEVENT_VERBOSE>
1224
1225	By default, AnyEvent will be completely silent except in fatal
1226	conditions. You can set this environment variable to make AnyEvent more
1227	talkative.
1228
1229	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1230	conditions, such as not being able to load the event model specified by
1231	C<PERL_ANYEVENT_MODEL>.
1232
1233	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1234	model it chooses.
1235
1236	=item C<PERL_ANYEVENT_STRICT>
1237
1238	AnyEvent does not do much argument checking by default, as thorough
1239	argument checking is very costly. Setting this variable to a true value
1240	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1241	check the arguments passed to most method calls. If it finds any problems
1242	it will croak.
1243
1244	In other words, enables "strict" mode.
1245
1246	Unlike C<use strict> it is definitely recommended ot keep it off in
1247	production.
1248
1249	=item C<PERL_ANYEVENT_MODEL>
1250
1251	This can be used to specify the event model to be used by AnyEvent, before
1252	auto detection and -probing kicks in. It must be a string consisting
1253	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1254	and the resulting module name is loaded and if the load was successful,
1255	used as event model. If it fails to load AnyEvent will proceed with
1256	auto detection and -probing.
1257
1258	This functionality might change in future versions.
1259
1260	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1261	could start your program like this:
1262
1263	PERL_ANYEVENT_MODEL=Perl perl ...
1264
1265	=item C<PERL_ANYEVENT_PROTOCOLS>
1266
1267	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1268	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1269	of auto probing).
1270
1271	Must be set to a comma-separated list of protocols or address families,
1272	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1273	used, and preference will be given to protocols mentioned earlier in the
1274	list.
1275
1276	This variable can effectively be used for denial-of-service attacks
1277	against local programs (e.g. when setuid), although the impact is likely
1278	small, as the program has to handle connection errors already-
1279
1280	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1281	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1282	- only support IPv4, never try to resolve or contact IPv6
1283	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1284	IPv6, but prefer IPv6 over IPv4.
1285
1286	=item C<PERL_ANYEVENT_EDNS0>
1287
1288	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1289	for DNS. This extension is generally useful to reduce DNS traffic, but
1290	some (broken) firewalls drop such DNS packets, which is why it is off by
1291	default.
1292
1293	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1294	EDNS0 in its DNS requests.
1295
1296	=item C<PERL_ANYEVENT_MAX_FORKS>
1297
1298	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1299	will create in parallel.
1300
1301	=back
1302		1977
1303	=head1 EXAMPLE PROGRAM	1978	=head1 EXAMPLE PROGRAM
1304		1979
1305	The following program uses an I/O watcher to read data from STDIN, a timer	1980	The following program uses an I/O watcher to read data from STDIN, a timer
1306	to display a message once per second, and a condition variable to quit the	1981	to display a message once per second, and a condition variable to quit the
…		…
1319	warn "read: $input\n"; # output what has been read	1994	warn "read: $input\n"; # output what has been read
1320	$cv->send if $input =~ /^q/i; # quit program if /^q/i	1995	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1321	},	1996	},
1322	);	1997	);
1323		1998
1324	my $time_watcher; # can only be used once
1325
1326	sub new_timer {
1327	$timer = AnyEvent->timer (after => 1, cb => sub {	1999	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1328	warn "timeout\n"; # print 'timeout' about every second	2000	warn "timeout\n"; # print 'timeout' at most every second
1329	&new_timer; # and restart the time
1330	});	2001	});
1331	}
1332
1333	new_timer; # create first timer
1334		2002
1335	$cv->recv; # wait until user enters /^q/i	2003	$cv->recv; # wait until user enters /^q/i
1336		2004
1337	=head1 REAL-WORLD EXAMPLE	2005	=head1 REAL-WORLD EXAMPLE
1338		2006
…		…
1411		2079
1412	The actual code goes further and collects all errors (C<die>s, exceptions)	2080	The actual code goes further and collects all errors (C<die>s, exceptions)
1413	that occurred during request processing. The C<result> method detects	2081	that occurred during request processing. The C<result> method detects
1414	whether an exception as thrown (it is stored inside the $txn object)	2082	whether an exception as thrown (it is stored inside the $txn object)
1415	and just throws the exception, which means connection errors and other	2083	and just throws the exception, which means connection errors and other
1416	problems get reported tot he code that tries to use the result, not in a	2084	problems get reported to the code that tries to use the result, not in a
1417	random callback.	2085	random callback.
1418		2086
1419	All of this enables the following usage styles:	2087	All of this enables the following usage styles:
1420		2088
1421	1. Blocking:	2089	1. Blocking:
…		…
1469	through AnyEvent. The benchmark creates a lot of timers (with a zero	2137	through AnyEvent. The benchmark creates a lot of timers (with a zero
1470	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2138	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1471	which it is), lets them fire exactly once and destroys them again.	2139	which it is), lets them fire exactly once and destroys them again.
1472		2140
1473	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2141	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1474	distribution.	2142	distribution. It uses the L<AE> interface, which makes a real difference
		2143	for the EV and Perl backends only.
1475		2144
1476	=head3 Explanation of the columns	2145	=head3 Explanation of the columns
1477		2146
1478	I<watcher> is the number of event watchers created/destroyed. Since	2147	I<watcher> is the number of event watchers created/destroyed. Since
1479	different event models feature vastly different performances, each event	2148	different event models feature vastly different performances, each event
…		…
1500	watcher.	2169	watcher.
1501		2170
1502	=head3 Results	2171	=head3 Results
1503		2172
1504	name watchers bytes create invoke destroy comment	2173	name watchers bytes create invoke destroy comment
1505	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2174	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1506	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2175	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1507	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2176	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1508	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2177	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1509	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2178	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1510	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2179	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2180	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2181	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1511	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2182	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1512	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2183	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1513	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2184	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1514	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2185	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1515		2186
1516	=head3 Discussion	2187	=head3 Discussion
1517		2188
1518	The benchmark does I<not> measure scalability of the event loop very	2189	The benchmark does I<not> measure scalability of the event loop very
1519	well. For example, a select-based event loop (such as the pure perl one)	2190	well. For example, a select-based event loop (such as the pure perl one)
…		…
1531	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2202	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1532	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2203	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1533	cycles with POE.	2204	cycles with POE.
1534		2205
1535	C<EV> is the sole leader regarding speed and memory use, which are both	2206	C<EV> is the sole leader regarding speed and memory use, which are both
1536	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2207	maximal/minimal, respectively. When using the L<AE> API there is zero
		2208	overhead (when going through the AnyEvent API create is about 5-6 times
		2209	slower, with other times being equal, so still uses far less memory than
1537	far less memory than any other event loop and is still faster than Event	2210	any other event loop and is still faster than Event natively).
1538	natively.
1539		2211
1540	The pure perl implementation is hit in a few sweet spots (both the	2212	The pure perl implementation is hit in a few sweet spots (both the
1541	constant timeout and the use of a single fd hit optimisations in the perl	2213	constant timeout and the use of a single fd hit optimisations in the perl
1542	interpreter and the backend itself). Nevertheless this shows that it	2214	interpreter and the backend itself). Nevertheless this shows that it
1543	adds very little overhead in itself. Like any select-based backend its	2215	adds very little overhead in itself. Like any select-based backend its
1544	performance becomes really bad with lots of file descriptors (and few of	2216	performance becomes really bad with lots of file descriptors (and few of
1545	them active), of course, but this was not subject of this benchmark.	2217	them active), of course, but this was not subject of this benchmark.
1546		2218
1547	The C<Event> module has a relatively high setup and callback invocation	2219	The C<Event> module has a relatively high setup and callback invocation
1548	cost, but overall scores in on the third place.	2220	cost, but overall scores in on the third place.
		2221
		2222	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2223	when using its pure perl backend.
1549		2224
1550	C<Glib>'s memory usage is quite a bit higher, but it features a	2225	C<Glib>'s memory usage is quite a bit higher, but it features a
1551	faster callback invocation and overall ends up in the same class as	2226	faster callback invocation and overall ends up in the same class as
1552	C<Event>. However, Glib scales extremely badly, doubling the number of	2227	C<Event>. However, Glib scales extremely badly, doubling the number of
1553	watchers increases the processing time by more than a factor of four,	2228	watchers increases the processing time by more than a factor of four,
…		…
1614	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2289	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1615	(1%) are active. This mirrors the activity of large servers with many	2290	(1%) are active. This mirrors the activity of large servers with many
1616	connections, most of which are idle at any one point in time.	2291	connections, most of which are idle at any one point in time.
1617		2292
1618	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2293	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1619	distribution.	2294	distribution. It uses the L<AE> interface, which makes a real difference
		2295	for the EV and Perl backends only.
1620		2296
1621	=head3 Explanation of the columns	2297	=head3 Explanation of the columns
1622		2298
1623	I<sockets> is the number of sockets, and twice the number of "servers" (as	2299	I<sockets> is the number of sockets, and twice the number of "servers" (as
1624	each server has a read and write socket end).	2300	each server has a read and write socket end).
…		…
1631	it to another server. This includes deleting the old timeout and creating	2307	it to another server. This includes deleting the old timeout and creating
1632	a new one that moves the timeout into the future.	2308	a new one that moves the timeout into the future.
1633		2309
1634	=head3 Results	2310	=head3 Results
1635		2311
1636	name sockets create request	2312	name sockets create request
1637	EV 20000 69.01 11.16	2313	EV 20000 62.66 7.99
1638	Perl 20000 73.32 35.87	2314	Perl 20000 68.32 32.64
1639	Event 20000 212.62 257.32	2315	IOAsync 20000 174.06 101.15 epoll
1640	Glib 20000 651.16 1896.30	2316	IOAsync 20000 174.67 610.84 poll
		2317	Event 20000 202.69 242.91
		2318	Glib 20000 557.01 1689.52
1641	POE 20000 349.67 12317.24 uses POE::Loop::Event	2319	POE 20000 341.54 12086.32 uses POE::Loop::Event
1642		2320
1643	=head3 Discussion	2321	=head3 Discussion
1644		2322
1645	This benchmark I<does> measure scalability and overall performance of the	2323	This benchmark I<does> measure scalability and overall performance of the
1646	particular event loop.	2324	particular event loop.
…		…
1648	EV is again fastest. Since it is using epoll on my system, the setup time	2326	EV is again fastest. Since it is using epoll on my system, the setup time
1649	is relatively high, though.	2327	is relatively high, though.
1650		2328
1651	Perl surprisingly comes second. It is much faster than the C-based event	2329	Perl surprisingly comes second. It is much faster than the C-based event
1652	loops Event and Glib.	2330	loops Event and Glib.
		2331
		2332	IO::Async performs very well when using its epoll backend, and still quite
		2333	good compared to Glib when using its pure perl backend.
1653		2334
1654	Event suffers from high setup time as well (look at its code and you will	2335	Event suffers from high setup time as well (look at its code and you will
1655	understand why). Callback invocation also has a high overhead compared to	2336	understand why). Callback invocation also has a high overhead compared to
1656	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2337	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1657	uses select or poll in basically all documented configurations.	2338	uses select or poll in basically all documented configurations.
…		…
1720	=item * C-based event loops perform very well with small number of	2401	=item * C-based event loops perform very well with small number of
1721	watchers, as the management overhead dominates.	2402	watchers, as the management overhead dominates.
1722		2403
1723	=back	2404	=back
1724		2405
		2406	=head2 THE IO::Lambda BENCHMARK
		2407
		2408	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2409	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2410	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2411	shouldn't come as a surprise to anybody). As such, the benchmark is
		2412	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2413	very optimal. But how would AnyEvent compare when used without the extra
		2414	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2415
		2416	The benchmark itself creates an echo-server, and then, for 500 times,
		2417	connects to the echo server, sends a line, waits for the reply, and then
		2418	creates the next connection. This is a rather bad benchmark, as it doesn't
		2419	test the efficiency of the framework or much non-blocking I/O, but it is a
		2420	benchmark nevertheless.
		2421
		2422	name runtime
		2423	Lambda/select 0.330 sec
		2424	+ optimized 0.122 sec
		2425	Lambda/AnyEvent 0.327 sec
		2426	+ optimized 0.138 sec
		2427	Raw sockets/select 0.077 sec
		2428	POE/select, components 0.662 sec
		2429	POE/select, raw sockets 0.226 sec
		2430	POE/select, optimized 0.404 sec
		2431
		2432	AnyEvent/select/nb 0.085 sec
		2433	AnyEvent/EV/nb 0.068 sec
		2434	+state machine 0.134 sec
		2435
		2436	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2437	benchmarks actually make blocking connects and use 100% blocking I/O,
		2438	defeating the purpose of an event-based solution. All of the newly
		2439	written AnyEvent benchmarks use 100% non-blocking connects (using
		2440	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2441	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2442	generally require a lot more bookkeeping and event handling than blocking
		2443	connects (which involve a single syscall only).
		2444
		2445	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2446	offers similar expressive power as POE and IO::Lambda, using conventional
		2447	Perl syntax. This means that both the echo server and the client are 100%
		2448	non-blocking, further placing it at a disadvantage.
		2449
		2450	As you can see, the AnyEvent + EV combination even beats the
		2451	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2452	backend easily beats IO::Lambda and POE.
		2453
		2454	And even the 100% non-blocking version written using the high-level (and
		2455	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2456	higher level ("unoptimised") abstractions by a large margin, even though
		2457	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2458
		2459	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2460	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2461	part of the IO::Lambda distribution and were used without any changes.
		2462
		2463
		2464	=head1 SIGNALS
		2465
		2466	AnyEvent currently installs handlers for these signals:
		2467
		2468	=over 4
		2469
		2470	=item SIGCHLD
		2471
		2472	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2473	emulation for event loops that do not support them natively. Also, some
		2474	event loops install a similar handler.
		2475
		2476	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2477	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2478
		2479	=item SIGPIPE
		2480
		2481	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2482	when AnyEvent gets loaded.
		2483
		2484	The rationale for this is that AnyEvent users usually do not really depend
		2485	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2486	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2487	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2488	some random socket.
		2489
		2490	The rationale for installing a no-op handler as opposed to ignoring it is
		2491	that this way, the handler will be restored to defaults on exec.
		2492
		2493	Feel free to install your own handler, or reset it to defaults.
		2494
		2495	=back
		2496
		2497	=cut
		2498
		2499	undef $SIG{CHLD}
		2500	if $SIG{CHLD} eq 'IGNORE';
		2501
		2502	$SIG{PIPE} = sub { }
		2503	unless defined $SIG{PIPE};
		2504
		2505	=head1 RECOMMENDED/OPTIONAL MODULES
		2506
		2507	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2508	its built-in modules) are required to use it.
		2509
		2510	That does not mean that AnyEvent won't take advantage of some additional
		2511	modules if they are installed.
		2512
		2513	This section explains which additional modules will be used, and how they
		2514	affect AnyEvent's operation.
		2515
		2516	=over 4
		2517
		2518	=item L<Async::Interrupt>
		2519
		2520	This slightly arcane module is used to implement fast signal handling: To
		2521	my knowledge, there is no way to do completely race-free and quick
		2522	signal handling in pure perl. To ensure that signals still get
		2523	delivered, AnyEvent will start an interval timer to wake up perl (and
		2524	catch the signals) with some delay (default is 10 seconds, look for
		2525	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2526
		2527	If this module is available, then it will be used to implement signal
		2528	catching, which means that signals will not be delayed, and the event loop
		2529	will not be interrupted regularly, which is more efficient (and good for
		2530	battery life on laptops).
		2531
		2532	This affects not just the pure-perl event loop, but also other event loops
		2533	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2534
		2535	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2536	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2537	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2538	does nothing for those backends.
		2539
		2540	=item L<EV>
		2541
		2542	This module isn't really "optional", as it is simply one of the backend
		2543	event loops that AnyEvent can use. However, it is simply the best event
		2544	loop available in terms of features, speed and stability: It supports
		2545	the AnyEvent API optimally, implements all the watcher types in XS, does
		2546	automatic timer adjustments even when no monotonic clock is available,
		2547	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2548	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2549	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2550
		2551	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2552	then this module will do nothing for you.
		2553
		2554	=item L<Guard>
		2555
		2556	The guard module, when used, will be used to implement
		2557	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2558	lot less memory), but otherwise doesn't affect guard operation much. It is
		2559	purely used for performance.
		2560
		2561	=item L<JSON> and L<JSON::XS>
		2562
		2563	One of these modules is required when you want to read or write JSON data
		2564	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2565	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2566
		2567	=item L<Net::SSLeay>
		2568
		2569	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2570	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2571	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2572
		2573	=item L<Time::HiRes>
		2574
		2575	This module is part of perl since release 5.008. It will be used when the
		2576	chosen event library does not come with a timing source of its own. The
		2577	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2578	try to use a monotonic clock for timing stability.
		2579
		2580	=back
		2581
1725		2582
1726	=head1 FORK	2583	=head1 FORK
1727		2584
1728	Most event libraries are not fork-safe. The ones who are usually are	2585	Most event libraries are not fork-safe. The ones who are usually are
1729	because they rely on inefficient but fork-safe C<select> or C<poll>	2586	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1730	calls. Only L<EV> is fully fork-aware.	2587	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2588	are usually badly thought-out hacks that are incompatible with fork in
		2589	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2590	continue event-processing in both parent and child (or both, if you know
		2591	what you are doing).
		2592
		2593	This means that, in general, you cannot fork and do event processing in
		2594	the child if the event library was initialised before the fork (which
		2595	usually happens when the first AnyEvent watcher is created, or the library
		2596	is loaded).
1731		2597
1732	If you have to fork, you must either do so I<before> creating your first	2598	If you have to fork, you must either do so I<before> creating your first
1733	watcher OR you must not use AnyEvent at all in the child.	2599	watcher OR you must not use AnyEvent at all in the child OR you must do
		2600	something completely out of the scope of AnyEvent.
		2601
		2602	The problem of doing event processing in the parent I<and> the child
		2603	is much more complicated: even for backends that I<are> fork-aware or
		2604	fork-safe, their behaviour is not usually what you want: fork clones all
		2605	watchers, that means all timers, I/O watchers etc. are active in both
		2606	parent and child, which is almost never what you want. USing C<exec>
		2607	to start worker children from some kind of manage rprocess is usually
		2608	preferred, because it is much easier and cleaner, at the expense of having
		2609	to have another binary.
1734		2610
1735		2611
1736	=head1 SECURITY CONSIDERATIONS	2612	=head1 SECURITY CONSIDERATIONS
1737		2613
1738	AnyEvent can be forced to load any event model via	2614	AnyEvent can be forced to load any event model via
…		…
1750	use AnyEvent;	2626	use AnyEvent;
1751		2627
1752	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2628	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1753	be used to probe what backend is used and gain other information (which is	2629	be used to probe what backend is used and gain other information (which is
1754	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2630	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1755	$ENV{PERL_ANYEGENT_STRICT}.	2631	$ENV{PERL_ANYEVENT_STRICT}.
		2632
		2633	Note that AnyEvent will remove I<all> environment variables starting with
		2634	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2635	enabled.
1756		2636
1757		2637
1758	=head1 BUGS	2638	=head1 BUGS
1759		2639
1760	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2640	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1761	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2641	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1762	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2642	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1763	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2643	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1764	pronounced).	2644	pronounced).
1765		2645
1766		2646
1767	=head1 SEE ALSO	2647	=head1 SEE ALSO
		2648
		2649	Tutorial/Introduction: L<AnyEvent::Intro>.
		2650
		2651	FAQ: L<AnyEvent::FAQ>.
1768		2652
1769	Utility functions: L<AnyEvent::Util>.	2653	Utility functions: L<AnyEvent::Util>.
1770		2654
1771	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2655	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1772	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2656	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1773		2657
1774	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2658	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1775	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2659	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1776	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2660	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1777	L<AnyEvent::Impl::POE>.	2661	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1778		2662
1779	Non-blocking file handles, sockets, TCP clients and	2663	Non-blocking file handles, sockets, TCP clients and
1780	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2664	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1781		2665
1782	Asynchronous DNS: L<AnyEvent::DNS>.	2666	Asynchronous DNS: L<AnyEvent::DNS>.
1783		2667
1784	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2668	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1785		2669
1786	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2670	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2671	L<AnyEvent::HTTP>.
1787		2672
1788		2673
1789	=head1 AUTHOR	2674	=head1 AUTHOR
1790		2675
1791	Marc Lehmann <schmorp@schmorp.de>	2676	Marc Lehmann <schmorp@schmorp.de>

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