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Revision 1.98 by root, Sun Apr 27 16:31:48 2008 UTC vs.
Revision 1.252 by root, Tue Jul 21 03:30:02 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - events independent of event loop implementation
4		4
5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		35	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	36	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Respository>, at L<http://anyevent.schmorp.de>, for more info.
22		53
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		55
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
27		58
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	59	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	60	policy> and AnyEvent is I<small and efficient>.
30		61
31	First and foremost, I<AnyEvent is not an event model> itself, it only	62	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	63	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	64	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	65	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	66	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	67	cannot change this, but it can hide the differences between those event
		68	loops.
37		69
38	The goal of AnyEvent is to offer module authors the ability to do event	70	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	71	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	72	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	73	module users into the same thing by forcing them to use the same event
42	model you use.	74	model you use.
43		75
44	For modules like POE or IO::Async (which is a total misnomer as it is	76	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	77	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	78	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	79	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	80	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	81	module are I<also> forced to use the same event loop you use.
50		82
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	84	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	85	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	86	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	87	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	88	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	89	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	90	to AnyEvent, too, so it is future-proof).
59		91
60	In addition to being free of having to use I<the one and only true event	92	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	93	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enourmous amount of code and strict rules you have to	94	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	95	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	96	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	97	technically possible.
66		98
		99	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		100	of useful functionality, such as an asynchronous DNS resolver, 100%
		101	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		102	such as Windows) and lots of real-world knowledge and workarounds for
		103	platform bugs and differences.
		104
67	Of course, if you want lots of policy (this can arguably be somewhat	105	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	106	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	107	model, you should I<not> use this module.
70
71	#TODO#
72
73	Net::IRC3
74	AnyEvent::HTTPD
75	AnyEvent::DNS
76	IO::AnyEvent
77	Net::FPing
78	Net::XMPP2
79	Coro
80
81	AnyEvent::IRC
82	AnyEvent::HTTPD
83	AnyEvent::DNS
84	AnyEvent::Handle
85	AnyEvent::Socket
86	AnyEvent::FPing
87	AnyEvent::XMPP
88	AnyEvent::SNMP
89	Coro
90		108
91	=head1 DESCRIPTION	109	=head1 DESCRIPTION
92		110
93	L<AnyEvent> provides an identical interface to multiple event loops. This	111	L<AnyEvent> provides an identical interface to multiple event loops. This
94	allows module authors to utilise an event loop without forcing module	112	allows module authors to utilise an event loop without forcing module
…		…
98	The interface itself is vaguely similar, but not identical to the L<Event>	116	The interface itself is vaguely similar, but not identical to the L<Event>
99	module.	117	module.
100		118
101	During the first call of any watcher-creation method, the module tries	119	During the first call of any watcher-creation method, the module tries
102	to detect the currently loaded event loop by probing whether one of the	120	to detect the currently loaded event loop by probing whether one of the
103	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	121	following modules is already loaded: L<EV>,
104	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	122	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
105	L<POE>. The first one found is used. If none are found, the module tries	123	L<POE>. The first one found is used. If none are found, the module tries
106	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	124	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
107	adaptor should always succeed) in the order given. The first one that can	125	adaptor should always succeed) in the order given. The first one that can
108	be successfully loaded will be used. If, after this, still none could be	126	be successfully loaded will be used. If, after this, still none could be
…		…
122	starts using it, all bets are off. Maybe you should tell their authors to	140	starts using it, all bets are off. Maybe you should tell their authors to
123	use AnyEvent so their modules work together with others seamlessly...	141	use AnyEvent so their modules work together with others seamlessly...
124		142
125	The pure-perl implementation of AnyEvent is called	143	The pure-perl implementation of AnyEvent is called
126	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	144	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
127	explicitly.	145	explicitly and enjoy the high availability of that event loop :)
128		146
129	=head1 WATCHERS	147	=head1 WATCHERS
130		148
131	AnyEvent has the central concept of a I<watcher>, which is an object that	149	AnyEvent has the central concept of a I<watcher>, which is an object that
132	stores relevant data for each kind of event you are waiting for, such as	150	stores relevant data for each kind of event you are waiting for, such as
133	the callback to call, the filehandle to watch, etc.	151	the callback to call, the file handle to watch, etc.
134		152
135	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
136	creating a watcher it will immediately "watch" for events and invoke the	154	creating a watcher it will immediately "watch" for events and invoke the
137	callback when the event occurs (of course, only when the event model	155	callback when the event occurs (of course, only when the event model
138	is in control).	156	is in control).
139		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		160	callbacks must not C<die> >>. The former is good programming practise in
		161	Perl and the latter stems from the fact that exception handling differs
		162	widely between event loops.
		163
140	To disable the watcher you have to destroy it (e.g. by setting the	164	To disable the watcher you have to destroy it (e.g. by setting the
141	variable you store it in to C<undef> or otherwise deleting all references	165	variable you store it in to C<undef> or otherwise deleting all references
142	to it).	166	to it).
143		167
144	All watchers are created by calling a method on the C<AnyEvent> class.	168	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
146	Many watchers either are used with "recursion" (repeating timers for	170	Many watchers either are used with "recursion" (repeating timers for
147	example), or need to refer to their watcher object in other ways.	171	example), or need to refer to their watcher object in other ways.
148		172
149	An any way to achieve that is this pattern:	173	An any way to achieve that is this pattern:
150		174
151	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	175	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
152	# you can use $w here, for example to undef it	176	# you can use $w here, for example to undef it
153	undef $w;	177	undef $w;
154	});	178	});
155		179
156	Note that C<my $w; $w => combination. This is necessary because in Perl,	180	Note that C<my $w; $w => combination. This is necessary because in Perl,
157	my variables are only visible after the statement in which they are	181	my variables are only visible after the statement in which they are
158	declared.	182	declared.
159		183
160	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
161		185
162	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	186	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
163	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
164		188
165	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	189	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		190	for events (AnyEvent might or might not keep a reference to this file
		191	handle). Note that only file handles pointing to things for which
		192	non-blocking operation makes sense are allowed. This includes sockets,
		193	most character devices, pipes, fifos and so on, but not for example files
		194	or block devices.
		195
166	for events. C<poll> must be a string that is either C<r> or C<w>,	196	C<poll> must be a string that is either C<r> or C<w>, which creates a
167	which creates a watcher waiting for "r"eadable or "w"ritable events,	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
168	respectively. C<cb> is the callback to invoke each time the file handle	199	C<cb> is the callback to invoke each time the file handle becomes ready.
169	becomes ready.
170		200
171	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
172	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
173	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
174		204
…		…
178		208
179	Some event loops issue spurious readyness notifications, so you should	209	Some event loops issue spurious readyness notifications, so you should
180	always use non-blocking calls when reading/writing from/to your file	210	always use non-blocking calls when reading/writing from/to your file
181	handles.	211	handles.
182		212
183	Example:
184
185	# wait for readability of STDIN, then read a line and disable the watcher	213	Example: wait for readability of STDIN, then read a line and disable the
		214	watcher.
		215
186	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	216	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
187	chomp (my $input = <STDIN>);	217	chomp (my $input = <STDIN>);
188	warn "read: $input\n";	218	warn "read: $input\n";
189	undef $w;	219	undef $w;
190	});	220	});
…		…
200		230
201	Although the callback might get passed parameters, their value and	231	Although the callback might get passed parameters, their value and
202	presence is undefined and you cannot rely on them. Portable AnyEvent	232	presence is undefined and you cannot rely on them. Portable AnyEvent
203	callbacks cannot use arguments passed to time watcher callbacks.	233	callbacks cannot use arguments passed to time watcher callbacks.
204		234
205	The timer callback will be invoked at most once: if you want a repeating	235	The callback will normally be invoked once only. If you specify another
206	timer you have to create a new watcher (this is a limitation by both Tk	236	parameter, C<interval>, as a strictly positive number (> 0), then the
207	and Glib).	237	callback will be invoked regularly at that interval (in fractional
		238	seconds) after the first invocation. If C<interval> is specified with a
		239	false value, then it is treated as if it were missing.
208		240
209	Example:	241	The callback will be rescheduled before invoking the callback, but no
		242	attempt is done to avoid timer drift in most backends, so the interval is
		243	only approximate.
210		244
211	# fire an event after 7.7 seconds	245	Example: fire an event after 7.7 seconds.
		246
212	my $w = AnyEvent->timer (after => 7.7, cb => sub {	247	my $w = AnyEvent->timer (after => 7.7, cb => sub {
213	warn "timeout\n";	248	warn "timeout\n";
214	});	249	});
215		250
216	# to cancel the timer:	251	# to cancel the timer:
217	undef $w;	252	undef $w;
218		253
219	Example 2:
220
221	# fire an event after 0.5 seconds, then roughly every second	254	Example 2: fire an event after 0.5 seconds, then roughly every second.
222	my $w;
223		255
224	my $cb = sub {
225	# cancel the old timer while creating a new one
226	$w = AnyEvent->timer (after => 1, cb => $cb);	256	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		257	warn "timeout\n";
227	};	258	};
228
229	# start the "loop" by creating the first watcher
230	$w = AnyEvent->timer (after => 0.5, cb => $cb);
231		259
232	=head3 TIMING ISSUES	260	=head3 TIMING ISSUES
233		261
234	There are two ways to handle timers: based on real time (relative, "fire	262	There are two ways to handle timers: based on real time (relative, "fire
235	in 10 seconds") and based on wallclock time (absolute, "fire at 12	263	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
247	timers.	275	timers.
248		276
249	AnyEvent always prefers relative timers, if available, matching the	277	AnyEvent always prefers relative timers, if available, matching the
250	AnyEvent API.	278	AnyEvent API.
251		279
		280	AnyEvent has two additional methods that return the "current time":
		281
		282	=over 4
		283
		284	=item AnyEvent->time
		285
		286	This returns the "current wallclock time" as a fractional number of
		287	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		288	return, and the result is guaranteed to be compatible with those).
		289
		290	It progresses independently of any event loop processing, i.e. each call
		291	will check the system clock, which usually gets updated frequently.
		292
		293	=item AnyEvent->now
		294
		295	This also returns the "current wallclock time", but unlike C<time>, above,
		296	this value might change only once per event loop iteration, depending on
		297	the event loop (most return the same time as C<time>, above). This is the
		298	time that AnyEvent's timers get scheduled against.
		299
		300	I<In almost all cases (in all cases if you don't care), this is the
		301	function to call when you want to know the current time.>
		302
		303	This function is also often faster then C<< AnyEvent->time >>, and
		304	thus the preferred method if you want some timestamp (for example,
		305	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		306
		307	The rest of this section is only of relevance if you try to be very exact
		308	with your timing, you can skip it without bad conscience.
		309
		310	For a practical example of when these times differ, consider L<Event::Lib>
		311	and L<EV> and the following set-up:
		312
		313	The event loop is running and has just invoked one of your callback at
		314	time=500 (assume no other callbacks delay processing). In your callback,
		315	you wait a second by executing C<sleep 1> (blocking the process for a
		316	second) and then (at time=501) you create a relative timer that fires
		317	after three seconds.
		318
		319	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		320	both return C<501>, because that is the current time, and the timer will
		321	be scheduled to fire at time=504 (C<501> + C<3>).
		322
		323	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		324	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		325	last event processing phase started. With L<EV>, your timer gets scheduled
		326	to run at time=503 (C<500> + C<3>).
		327
		328	In one sense, L<Event::Lib> is more exact, as it uses the current time
		329	regardless of any delays introduced by event processing. However, most
		330	callbacks do not expect large delays in processing, so this causes a
		331	higher drift (and a lot more system calls to get the current time).
		332
		333	In another sense, L<EV> is more exact, as your timer will be scheduled at
		334	the same time, regardless of how long event processing actually took.
		335
		336	In either case, if you care (and in most cases, you don't), then you
		337	can get whatever behaviour you want with any event loop, by taking the
		338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		339	account.
		340
		341	=item AnyEvent->now_update
		342
		343	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		344	the current time for each loop iteration (see the discussion of L<<
		345	AnyEvent->now >>, above).
		346
		347	When a callback runs for a long time (or when the process sleeps), then
		348	this "current" time will differ substantially from the real time, which
		349	might affect timers and time-outs.
		350
		351	When this is the case, you can call this method, which will update the
		352	event loop's idea of "current time".
		353
		354	Note that updating the time I<might> cause some events to be handled.
		355
		356	=back
		357
252	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
253		359
254	You can watch for signals using a signal watcher, C<signal> is the signal	360	You can watch for signals using a signal watcher, C<signal> is the signal
255	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	361	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
256	be invoked whenever a signal occurs.	362	callback to be invoked whenever a signal occurs.
257		363
258	Although the callback might get passed parameters, their value and	364	Although the callback might get passed parameters, their value and
259	presence is undefined and you cannot rely on them. Portable AnyEvent	365	presence is undefined and you cannot rely on them. Portable AnyEvent
260	callbacks cannot use arguments passed to signal watcher callbacks.	366	callbacks cannot use arguments passed to signal watcher callbacks.
261		367
262	Multiple signal occurances can be clumped together into one callback	368	Multiple signal occurrences can be clumped together into one callback
263	invocation, and callback invocation will be synchronous. synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
264	that it might take a while until the signal gets handled by the process,	370	that it might take a while until the signal gets handled by the process,
265	but it is guarenteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
266		372
267	The main advantage of using these watchers is that you can share a signal	373	The main advantage of using these watchers is that you can share a signal
268	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
269		376
270	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
271	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
272		380
273	Example: exit on SIGINT	381	Example: exit on SIGINT
274		382
275	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
276		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		392	seconds). This variable can be changed only before the first signal
		393	watcher is created, and should be left alone otherwise. Higher values
		394	will cause fewer spurious wake-ups, which is better for power and CPU
		395	saving. All these problems can be avoided by installing the optional
		396	L<Async::Interrupt> module. This will not work with inherently broken
		397	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		398	currently, as POE does it's own workaround with one-second latency). With
		399	those, you just have to suffer the delays.
		400
277	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
278		402
279	You can also watch on a child process exit and catch its exit status.	403	You can also watch on a child process exit and catch its exit status.
280		404
281	The child process is specified by the C<pid> argument (if set to C<0>, it	405	The child process is specified by the C<pid> argument (if set to C<0>, it
282	watches for any child process exit). The watcher will trigger as often	406	watches for any child process exit). The watcher will triggered only when
283	as status change for the child are received. This works by installing a	407	the child process has finished and an exit status is available, not on
284	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	any trace events (stopped/continued).
285	and exit status (as returned by waitpid), so unlike other watcher types,	409
286	you I<can> rely on child watcher callback arguments.	410	The callback will be called with the pid and exit status (as returned by
		411	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		412	callback arguments.
		413
		414	This watcher type works by installing a signal handler for C<SIGCHLD>,
		415	and since it cannot be shared, nothing else should use SIGCHLD or reap
		416	random child processes (waiting for specific child processes, e.g. inside
		417	C<system>, is just fine).
287		418
288	There is a slight catch to child watchers, however: you usually start them	419	There is a slight catch to child watchers, however: you usually start them
289	I<after> the child process was created, and this means the process could	420	I<after> the child process was created, and this means the process could
290	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
291		422
292	Not all event models handle this correctly (POE doesn't), but even for	423	Not all event models handle this correctly (neither POE nor IO::Async do,
		424	see their AnyEvent::Impl manpages for details), but even for event models
293	event models that I<do> handle this correctly, they usually need to be	425	that I<do> handle this correctly, they usually need to be loaded before
294	loaded before the process exits (i.e. before you fork in the first place).	426	the process exits (i.e. before you fork in the first place). AnyEvent's
		427	pure perl event loop handles all cases correctly regardless of when you
		428	start the watcher.
295		429
296	This means you cannot create a child watcher as the very first thing in an	430	This means you cannot create a child watcher as the very first
297	AnyEvent program, you I<have> to create at least one watcher before you	431	thing in an AnyEvent program, you I<have> to create at least one
298	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	432	watcher before you C<fork> the child (alternatively, you can call
		433	C<AnyEvent::detect>).
		434
		435	As most event loops do not support waiting for child events, they will be
		436	emulated by AnyEvent in most cases, in which the latency and race problems
		437	mentioned in the description of signal watchers apply.
299		438
300	Example: fork a process and wait for it	439	Example: fork a process and wait for it
301		440
302	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
303		442
304	AnyEvent::detect; # force event module to be initialised
305
306	my $pid = fork or exit 5;	443	my $pid = fork or exit 5;
307		444
308	my $w = AnyEvent->child (	445	my $w = AnyEvent->child (
309	pid => $pid,	446	pid => $pid,
310	cb => sub {	447	cb => sub {
311	my ($pid, $status) = @_;	448	my ($pid, $status) = @_;
312	warn "pid $pid exited with status $status";	449	warn "pid $pid exited with status $status";
313	$done->broadcast;	450	$done->send;
314	},	451	},
315	);	452	);
316		453
317	# do something else, then wait for process exit	454	# do something else, then wait for process exit
318	$done->wait;	455	$done->recv;
		456
		457	=head2 IDLE WATCHERS
		458
		459	Sometimes there is a need to do something, but it is not so important
		460	to do it instantly, but only when there is nothing better to do. This
		461	"nothing better to do" is usually defined to be "no other events need
		462	attention by the event loop".
		463
		464	Idle watchers ideally get invoked when the event loop has nothing
		465	better to do, just before it would block the process to wait for new
		466	events. Instead of blocking, the idle watcher is invoked.
		467
		468	Most event loops unfortunately do not really support idle watchers (only
		469	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		470	will simply call the callback "from time to time".
		471
		472	Example: read lines from STDIN, but only process them when the
		473	program is otherwise idle:
		474
		475	my @lines; # read data
		476	my $idle_w;
		477	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		478	push @lines, scalar <STDIN>;
		479
		480	# start an idle watcher, if not already done
		481	$idle_w ||= AnyEvent->idle (cb => sub {
		482	# handle only one line, when there are lines left
		483	if (my $line = shift @lines) {
		484	print "handled when idle: $line";
		485	} else {
		486	# otherwise disable the idle watcher again
		487	undef $idle_w;
		488	}
		489	});
		490	});
319		491
320	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
321		493
		494	If you are familiar with some event loops you will know that all of them
		495	require you to run some blocking "loop", "run" or similar function that
		496	will actively watch for new events and call your callbacks.
		497
		498	AnyEvent is slightly different: it expects somebody else to run the event
		499	loop and will only block when necessary (usually when told by the user).
		500
		501	The instrument to do that is called a "condition variable", so called
		502	because they represent a condition that must become true.
		503
		504	Now is probably a good time to look at the examples further below.
		505
322	Condition variables can be created by calling the C<< AnyEvent->condvar >>	506	Condition variables can be created by calling the C<< AnyEvent->condvar
323	method without any arguments.	507	>> method, usually without arguments. The only argument pair allowed is
		508	C<cb>, which specifies a callback to be called when the condition variable
		509	becomes true, with the condition variable as the first argument (but not
		510	the results).
324		511
325	A condition variable waits for a condition - precisely that the C<<	512	After creation, the condition variable is "false" until it becomes "true"
326	->broadcast >> method has been called.	513	by calling the C<send> method (or calling the condition variable as if it
		514	were a callback, read about the caveats in the description for the C<<
		515	->send >> method).
327		516
328	They are very useful to signal that a condition has been fulfilled, for	517	Condition variables are similar to callbacks, except that you can
		518	optionally wait for them. They can also be called merge points - points
		519	in time where multiple outstanding events have been processed. And yet
		520	another way to call them is transactions - each condition variable can be
		521	used to represent a transaction, which finishes at some point and delivers
		522	a result. And yet some people know them as "futures" - a promise to
		523	compute/deliver something that you can wait for.
		524
		525	Condition variables are very useful to signal that something has finished,
329	example, if you write a module that does asynchronous http requests,	526	for example, if you write a module that does asynchronous http requests,
330	then a condition variable would be the ideal candidate to signal the	527	then a condition variable would be the ideal candidate to signal the
331	availability of results.	528	availability of results. The user can either act when the callback is
		529	called or can synchronously C<< ->recv >> for the results.
332		530
333	You can also use condition variables to block your main program until	531	You can also use them to simulate traditional event loops - for example,
334	an event occurs - for example, you could C<< ->wait >> in your main	532	you can block your main program until an event occurs - for example, you
335	program until the user clicks the Quit button in your app, which would C<<	533	could C<< ->recv >> in your main program until the user clicks the Quit
336	->broadcast >> the "quit" event.	534	button of your app, which would C<< ->send >> the "quit" event.
337		535
338	Note that condition variables recurse into the event loop - if you have	536	Note that condition variables recurse into the event loop - if you have
339	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	537	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
340	lose. Therefore, condition variables are good to export to your caller, but	538	lose. Therefore, condition variables are good to export to your caller, but
341	you should avoid making a blocking wait yourself, at least in callbacks,	539	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	540	as this asks for trouble.
343		541
344	This object has two methods:	542	Condition variables are represented by hash refs in perl, and the keys
		543	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		544	easy (it is often useful to build your own transaction class on top of
		545	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		546	it's C<new> method in your own C<new> method.
345		547
346	=over 4	548	There are two "sides" to a condition variable - the "producer side" which
		549	eventually calls C<< -> send >>, and the "consumer side", which waits
		550	for the send to occur.
347		551
348	=item $cv->wait	552	Example: wait for a timer.
349
350	Wait (blocking if necessary) until the C<< ->broadcast >> method has been
351	called on c<$cv>, while servicing other watchers normally.
352
353	You can only wait once on a condition - additional calls will return
354	immediately.
355
356	Not all event models support a blocking wait - some die in that case
357	(programs might want to do that to stay interactive), so I<if you are
358	using this from a module, never require a blocking wait>, but let the
359	caller decide whether the call will block or not (for example, by coupling
360	condition variables with some kind of request results and supporting
361	callbacks so the caller knows that getting the result will not block,
362	while still suppporting blocking waits if the caller so desires).
363
364	Another reason I<never> to C<< ->wait >> in a module is that you cannot
365	sensibly have two C<< ->wait >>'s in parallel, as that would require
366	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
367	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
368	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
369	from different coroutines, however).
370
371	=item $cv->broadcast
372
373	Flag the condition as ready - a running C<< ->wait >> and all further
374	calls to C<wait> will (eventually) return after this method has been
375	called. If nobody is waiting the broadcast will be remembered..
376
377	=back
378
379	Example:
380		553
381	# wait till the result is ready	554	# wait till the result is ready
382	my $result_ready = AnyEvent->condvar;	555	my $result_ready = AnyEvent->condvar;
383		556
384	# do something such as adding a timer	557	# do something such as adding a timer
385	# or socket watcher the calls $result_ready->broadcast	558	# or socket watcher the calls $result_ready->send
386	# when the "result" is ready.	559	# when the "result" is ready.
387	# in this case, we simply use a timer:	560	# in this case, we simply use a timer:
388	my $w = AnyEvent->timer (	561	my $w = AnyEvent->timer (
389	after => 1,	562	after => 1,
390	cb => sub { $result_ready->broadcast },	563	cb => sub { $result_ready->send },
391	);	564	);
392		565
393	# this "blocks" (while handling events) till the watcher	566	# this "blocks" (while handling events) till the callback
394	# calls broadcast	567	# calls -<send
395	$result_ready->wait;	568	$result_ready->recv;
		569
		570	Example: wait for a timer, but take advantage of the fact that condition
		571	variables are also callable directly.
		572
		573	my $done = AnyEvent->condvar;
		574	my $delay = AnyEvent->timer (after => 5, cb => $done);
		575	$done->recv;
		576
		577	Example: Imagine an API that returns a condvar and doesn't support
		578	callbacks. This is how you make a synchronous call, for example from
		579	the main program:
		580
		581	use AnyEvent::CouchDB;
		582
		583	...
		584
		585	my @info = $couchdb->info->recv;
		586
		587	And this is how you would just set a callback to be called whenever the
		588	results are available:
		589
		590	$couchdb->info->cb (sub {
		591	my @info = $_[0]->recv;
		592	});
		593
		594	=head3 METHODS FOR PRODUCERS
		595
		596	These methods should only be used by the producing side, i.e. the
		597	code/module that eventually sends the signal. Note that it is also
		598	the producer side which creates the condvar in most cases, but it isn't
		599	uncommon for the consumer to create it as well.
		600
		601	=over 4
		602
		603	=item $cv->send (...)
		604
		605	Flag the condition as ready - a running C<< ->recv >> and all further
		606	calls to C<recv> will (eventually) return after this method has been
		607	called. If nobody is waiting the send will be remembered.
		608
		609	If a callback has been set on the condition variable, it is called
		610	immediately from within send.
		611
		612	Any arguments passed to the C<send> call will be returned by all
		613	future C<< ->recv >> calls.
		614
		615	Condition variables are overloaded so one can call them directly (as if
		616	they were a code reference). Calling them directly is the same as calling
		617	C<send>.
		618
		619	=item $cv->croak ($error)
		620
		621	Similar to send, but causes all call's to C<< ->recv >> to invoke
		622	C<Carp::croak> with the given error message/object/scalar.
		623
		624	This can be used to signal any errors to the condition variable
		625	user/consumer. Doing it this way instead of calling C<croak> directly
		626	delays the error detetcion, but has the overwhelmign advantage that it
		627	diagnoses the error at the place where the result is expected, and not
		628	deep in some event clalback without connection to the actual code causing
		629	the problem.
		630
		631	=item $cv->begin ([group callback])
		632
		633	=item $cv->end
		634
		635	These two methods can be used to combine many transactions/events into
		636	one. For example, a function that pings many hosts in parallel might want
		637	to use a condition variable for the whole process.
		638
		639	Every call to C<< ->begin >> will increment a counter, and every call to
		640	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		641	>>, the (last) callback passed to C<begin> will be executed. That callback
		642	is I<supposed> to call C<< ->send >>, but that is not required. If no
		643	callback was set, C<send> will be called without any arguments.
		644
		645	You can think of C<< $cv->send >> giving you an OR condition (one call
		646	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		647	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		648
		649	Let's start with a simple example: you have two I/O watchers (for example,
		650	STDOUT and STDERR for a program), and you want to wait for both streams to
		651	close before activating a condvar:
		652
		653	my $cv = AnyEvent->condvar;
		654
		655	$cv->begin; # first watcher
		656	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		657	defined sysread $fh1, my $buf, 4096
		658	or $cv->end;
		659	});
		660
		661	$cv->begin; # second watcher
		662	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		663	defined sysread $fh2, my $buf, 4096
		664	or $cv->end;
		665	});
		666
		667	$cv->recv;
		668
		669	This works because for every event source (EOF on file handle), there is
		670	one call to C<begin>, so the condvar waits for all calls to C<end> before
		671	sending.
		672
		673	The ping example mentioned above is slightly more complicated, as the
		674	there are results to be passwd back, and the number of tasks that are
		675	begung can potentially be zero:
		676
		677	my $cv = AnyEvent->condvar;
		678
		679	my %result;
		680	$cv->begin (sub { $cv->send (\%result) });
		681
		682	for my $host (@list_of_hosts) {
		683	$cv->begin;
		684	ping_host_then_call_callback $host, sub {
		685	$result{$host} = ...;
		686	$cv->end;
		687	};
		688	}
		689
		690	$cv->end;
		691
		692	This code fragment supposedly pings a number of hosts and calls
		693	C<send> after results for all then have have been gathered - in any
		694	order. To achieve this, the code issues a call to C<begin> when it starts
		695	each ping request and calls C<end> when it has received some result for
		696	it. Since C<begin> and C<end> only maintain a counter, the order in which
		697	results arrive is not relevant.
		698
		699	There is an additional bracketing call to C<begin> and C<end> outside the
		700	loop, which serves two important purposes: first, it sets the callback
		701	to be called once the counter reaches C<0>, and second, it ensures that
		702	C<send> is called even when C<no> hosts are being pinged (the loop
		703	doesn't execute once).
		704
		705	This is the general pattern when you "fan out" into multiple (but
		706	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
		707	the callback and ensure C<end> is called at least once, and then, for each
		708	subrequest you start, call C<begin> and for each subrequest you finish,
		709	call C<end>.
		710
		711	=back
		712
		713	=head3 METHODS FOR CONSUMERS
		714
		715	These methods should only be used by the consuming side, i.e. the
		716	code awaits the condition.
		717
		718	=over 4
		719
		720	=item $cv->recv
		721
		722	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
		723	>> methods have been called on c<$cv>, while servicing other watchers
		724	normally.
		725
		726	You can only wait once on a condition - additional calls are valid but
		727	will return immediately.
		728
		729	If an error condition has been set by calling C<< ->croak >>, then this
		730	function will call C<croak>.
		731
		732	In list context, all parameters passed to C<send> will be returned,
		733	in scalar context only the first one will be returned.
		734
		735	Note that doing a blocking wait in a callback is not supported by any
		736	event loop, that is, recursive invocation of a blocking C<< ->recv
		737	>> is not allowed, and the C<recv> call will C<croak> if such a
		738	condition is detected. This condition can be slightly loosened by using
		739	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		740	any thread that doesn't run the event loop itself.
		741
		742	Not all event models support a blocking wait - some die in that case
		743	(programs might want to do that to stay interactive), so I<if you are
		744	using this from a module, never require a blocking wait>. Instead, let the
		745	caller decide whether the call will block or not (for example, by coupling
		746	condition variables with some kind of request results and supporting
		747	callbacks so the caller knows that getting the result will not block,
		748	while still supporting blocking waits if the caller so desires).
		749
		750	You can ensure that C<< -recv >> never blocks by setting a callback and
		751	only calling C<< ->recv >> from within that callback (or at a later
		752	time). This will work even when the event loop does not support blocking
		753	waits otherwise.
		754
		755	=item $bool = $cv->ready
		756
		757	Returns true when the condition is "true", i.e. whether C<send> or
		758	C<croak> have been called.
		759
		760	=item $cb = $cv->cb ($cb->($cv))
		761
		762	This is a mutator function that returns the callback set and optionally
		763	replaces it before doing so.
		764
		765	The callback will be called when the condition becomes "true", i.e. when
		766	C<send> or C<croak> are called, with the only argument being the condition
		767	variable itself. Calling C<recv> inside the callback or at any later time
		768	is guaranteed not to block.
		769
		770	=back
		771
		772	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		773
		774	The available backend classes are (every class has its own manpage):
		775
		776	=over 4
		777
		778	=item Backends that are autoprobed when no other event loop can be found.
		779
		780	EV is the preferred backend when no other event loop seems to be in
		781	use. If EV is not installed, then AnyEvent will try Event, and, failing
		782	that, will fall back to its own pure-perl implementation, which is
		783	available everywhere as it comes with AnyEvent itself.
		784
		785	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		786	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		787	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		788
		789	=item Backends that are transparently being picked up when they are used.
		790
		791	These will be used when they are currently loaded when the first watcher
		792	is created, in which case it is assumed that the application is using
		793	them. This means that AnyEvent will automatically pick the right backend
		794	when the main program loads an event module before anything starts to
		795	create watchers. Nothing special needs to be done by the main program.
		796
		797	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		798	AnyEvent::Impl::Tk based on Tk, very broken.
		799	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		800	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		801
		802	=item Backends with special needs.
		803
		804	Qt requires the Qt::Application to be instantiated first, but will
		805	otherwise be picked up automatically. As long as the main program
		806	instantiates the application before any AnyEvent watchers are created,
		807	everything should just work.
		808
		809	AnyEvent::Impl::Qt based on Qt.
		810
		811	Support for IO::Async can only be partial, as it is too broken and
		812	architecturally limited to even support the AnyEvent API. It also
		813	is the only event loop that needs the loop to be set explicitly, so
		814	it can only be used by a main program knowing about AnyEvent. See
		815	L<AnyEvent::Impl::Async> for the gory details.
		816
		817	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		818
		819	=item Event loops that are indirectly supported via other backends.
		820
		821	Some event loops can be supported via other modules:
		822
		823	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		824
		825	B<WxWidgets> has no support for watching file handles. However, you can
		826	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		827	polls 20 times per second, which was considered to be too horrible to even
		828	consider for AnyEvent.
		829
		830	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		831	backend, so it can be supported through POE.
		832
		833	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		834	load L<POE> when detecting them, in the hope that POE will pick them up,
		835	in which case everything will be automatic.
		836
		837	=back
396		838
397	=head1 GLOBAL VARIABLES AND FUNCTIONS	839	=head1 GLOBAL VARIABLES AND FUNCTIONS
398		840
		841	These are not normally required to use AnyEvent, but can be useful to
		842	write AnyEvent extension modules.
		843
399	=over 4	844	=over 4
400		845
401	=item $AnyEvent::MODEL	846	=item $AnyEvent::MODEL
402		847
403	Contains C<undef> until the first watcher is being created. Then it	848	Contains C<undef> until the first watcher is being created, before the
		849	backend has been autodetected.
		850
404	contains the event model that is being used, which is the name of the	851	Afterwards it contains the event model that is being used, which is the
405	Perl class implementing the model. This class is usually one of the	852	name of the Perl class implementing the model. This class is usually one
406	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	853	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
407	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	854	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
408		855	will be C<urxvt::anyevent>).
409	The known classes so far are:
410
411	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
412	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
413	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
414	AnyEvent::Impl::Event based on Event, second best choice.
415	AnyEvent::Impl::Glib based on Glib, third-best choice.
416	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
417	AnyEvent::Impl::Tk based on Tk, very bad choice.
418	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
419	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
420	AnyEvent::Impl::POE based on POE, not generic enough for full support.
421
422	There is no support for WxWidgets, as WxWidgets has no support for
423	watching file handles. However, you can use WxWidgets through the
424	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
425	second, which was considered to be too horrible to even consider for
426	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
427	it's adaptor.
428
429	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
430	autodetecting them.
431		856
432	=item AnyEvent::detect	857	=item AnyEvent::detect
433		858
434	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	859	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
435	if necessary. You should only call this function right before you would	860	if necessary. You should only call this function right before you would
436	have created an AnyEvent watcher anyway, that is, as late as possible at	861	have created an AnyEvent watcher anyway, that is, as late as possible at
437	runtime.	862	runtime, and not e.g. while initialising of your module.
		863
		864	If you need to do some initialisation before AnyEvent watchers are
		865	created, use C<post_detect>.
		866
		867	=item $guard = AnyEvent::post_detect { BLOCK }
		868
		869	Arranges for the code block to be executed as soon as the event model is
		870	autodetected (or immediately if this has already happened).
		871
		872	The block will be executed I<after> the actual backend has been detected
		873	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		874	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		875	other initialisations - see the sources of L<AnyEvent::Strict> or
		876	L<AnyEvent::AIO> to see how this is used.
		877
		878	The most common usage is to create some global watchers, without forcing
		879	event module detection too early, for example, L<AnyEvent::AIO> creates
		880	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		881	avoid autodetecting the event module at load time.
		882
		883	If called in scalar or list context, then it creates and returns an object
		884	that automatically removes the callback again when it is destroyed (or
		885	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
		886	a case where this is useful.
		887
		888	Example: Create a watcher for the IO::AIO module and store it in
		889	C<$WATCHER>. Only do so after the event loop is initialised, though.
		890
		891	our WATCHER;
		892
		893	my $guard = AnyEvent::post_detect {
		894	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		895	};
		896
		897	# the ||= is important in case post_detect immediately runs the block,
		898	# as to not clobber the newly-created watcher. assigning both watcher and
		899	# post_detect guard to the same variable has the advantage of users being
		900	# able to just C<undef $WATCHER> if the watcher causes them grief.
		901
		902	$WATCHER ||= $guard;
		903
		904	=item @AnyEvent::post_detect
		905
		906	If there are any code references in this array (you can C<push> to it
		907	before or after loading AnyEvent), then they will called directly after
		908	the event loop has been chosen.
		909
		910	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		911	if it is defined then the event loop has already been detected, and the
		912	array will be ignored.
		913
		914	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		915	it,as it takes care of these details.
		916
		917	This variable is mainly useful for modules that can do something useful
		918	when AnyEvent is used and thus want to know when it is initialised, but do
		919	not need to even load it by default. This array provides the means to hook
		920	into AnyEvent passively, without loading it.
438		921
439	=back	922	=back
440		923
441	=head1 WHAT TO DO IN A MODULE	924	=head1 WHAT TO DO IN A MODULE
442		925
…		…
446	Be careful when you create watchers in the module body - AnyEvent will	929	Be careful when you create watchers in the module body - AnyEvent will
447	decide which event module to use as soon as the first method is called, so	930	decide which event module to use as soon as the first method is called, so
448	by calling AnyEvent in your module body you force the user of your module	931	by calling AnyEvent in your module body you force the user of your module
449	to load the event module first.	932	to load the event module first.
450		933
451	Never call C<< ->wait >> on a condition variable unless you I<know> that	934	Never call C<< ->recv >> on a condition variable unless you I<know> that
452	the C<< ->broadcast >> method has been called on it already. This is	935	the C<< ->send >> method has been called on it already. This is
453	because it will stall the whole program, and the whole point of using	936	because it will stall the whole program, and the whole point of using
454	events is to stay interactive.	937	events is to stay interactive.
455		938
456	It is fine, however, to call C<< ->wait >> when the user of your module	939	It is fine, however, to call C<< ->recv >> when the user of your module
457	requests it (i.e. if you create a http request object ad have a method	940	requests it (i.e. if you create a http request object ad have a method
458	called C<results> that returns the results, it should call C<< ->wait >>	941	called C<results> that returns the results, it should call C<< ->recv >>
459	freely, as the user of your module knows what she is doing. always).	942	freely, as the user of your module knows what she is doing. always).
460		943
461	=head1 WHAT TO DO IN THE MAIN PROGRAM	944	=head1 WHAT TO DO IN THE MAIN PROGRAM
462		945
463	There will always be a single main program - the only place that should	946	There will always be a single main program - the only place that should
…		…
465		948
466	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	949	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
467	do anything special (it does not need to be event-based) and let AnyEvent	950	do anything special (it does not need to be event-based) and let AnyEvent
468	decide which implementation to chose if some module relies on it.	951	decide which implementation to chose if some module relies on it.
469		952
470	If the main program relies on a specific event model. For example, in	953	If the main program relies on a specific event model - for example, in
471	Gtk2 programs you have to rely on the Glib module. You should load the	954	Gtk2 programs you have to rely on the Glib module - you should load the
472	event module before loading AnyEvent or any module that uses it: generally	955	event module before loading AnyEvent or any module that uses it: generally
473	speaking, you should load it as early as possible. The reason is that	956	speaking, you should load it as early as possible. The reason is that
474	modules might create watchers when they are loaded, and AnyEvent will	957	modules might create watchers when they are loaded, and AnyEvent will
475	decide on the event model to use as soon as it creates watchers, and it	958	decide on the event model to use as soon as it creates watchers, and it
476	might chose the wrong one unless you load the correct one yourself.	959	might chose the wrong one unless you load the correct one yourself.
477		960
478	You can chose to use a rather inefficient pure-perl implementation by	961	You can chose to use a pure-perl implementation by loading the
479	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	962	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
480	behaviour everywhere, but letting AnyEvent chose is generally better.	963	everywhere, but letting AnyEvent chose the model is generally better.
		964
		965	=head2 MAINLOOP EMULATION
		966
		967	Sometimes (often for short test scripts, or even standalone programs who
		968	only want to use AnyEvent), you do not want to run a specific event loop.
		969
		970	In that case, you can use a condition variable like this:
		971
		972	AnyEvent->condvar->recv;
		973
		974	This has the effect of entering the event loop and looping forever.
		975
		976	Note that usually your program has some exit condition, in which case
		977	it is better to use the "traditional" approach of storing a condition
		978	variable somewhere, waiting for it, and sending it when the program should
		979	exit cleanly.
		980
		981
		982	=head1 OTHER MODULES
		983
		984	The following is a non-exhaustive list of additional modules that use
		985	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
		986	modules and other event loops in the same program. Some of the modules
		987	come with AnyEvent, most are available via CPAN.
		988
		989	=over 4
		990
		991	=item L<AnyEvent::Util>
		992
		993	Contains various utility functions that replace often-used but blocking
		994	functions such as C<inet_aton> by event-/callback-based versions.
		995
		996	=item L<AnyEvent::Socket>
		997
		998	Provides various utility functions for (internet protocol) sockets,
		999	addresses and name resolution. Also functions to create non-blocking tcp
		1000	connections or tcp servers, with IPv6 and SRV record support and more.
		1001
		1002	=item L<AnyEvent::Handle>
		1003
		1004	Provide read and write buffers, manages watchers for reads and writes,
		1005	supports raw and formatted I/O, I/O queued and fully transparent and
		1006	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1007
		1008	=item L<AnyEvent::DNS>
		1009
		1010	Provides rich asynchronous DNS resolver capabilities.
		1011
		1012	=item L<AnyEvent::HTTP>
		1013
		1014	A simple-to-use HTTP library that is capable of making a lot of concurrent
		1015	HTTP requests.
		1016
		1017	=item L<AnyEvent::HTTPD>
		1018
		1019	Provides a simple web application server framework.
		1020
		1021	=item L<AnyEvent::FastPing>
		1022
		1023	The fastest ping in the west.
		1024
		1025	=item L<AnyEvent::DBI>
		1026
		1027	Executes L<DBI> requests asynchronously in a proxy process.
		1028
		1029	=item L<AnyEvent::AIO>
		1030
		1031	Truly asynchronous I/O, should be in the toolbox of every event
		1032	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1033	together.
		1034
		1035	=item L<AnyEvent::BDB>
		1036
		1037	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1038	L<BDB> and AnyEvent together.
		1039
		1040	=item L<AnyEvent::GPSD>
		1041
		1042	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1043
		1044	=item L<AnyEvent::IRC>
		1045
		1046	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1047
		1048	=item L<AnyEvent::XMPP>
		1049
		1050	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1051	Net::XMPP2>.
		1052
		1053	=item L<AnyEvent::IGS>
		1054
		1055	A non-blocking interface to the Internet Go Server protocol (used by
		1056	L<App::IGS>).
		1057
		1058	=item L<Net::FCP>
		1059
		1060	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		1061	of AnyEvent.
		1062
		1063	=item L<Event::ExecFlow>
		1064
		1065	High level API for event-based execution flow control.
		1066
		1067	=item L<Coro>
		1068
		1069	Has special support for AnyEvent via L<Coro::AnyEvent>.
		1070
		1071	=back
481		1072
482	=cut	1073	=cut
483		1074
484	package AnyEvent;	1075	package AnyEvent;
485		1076
		1077	# basically a tuned-down version of common::sense
		1078	sub common_sense {
486	no warnings;	1079	# no warnings
487	use strict;	1080	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1081	# use strict vars subs
		1082	$^H |= 0x00000600;
		1083	}
488		1084
		1085	BEGIN { AnyEvent::common_sense }
		1086
489	use Carp;	1087	use Carp ();
490		1088
491	our $VERSION = '3.3';	1089	our $VERSION = 4.86;
492	our $MODEL;	1090	our $MODEL;
493		1091
494	our $AUTOLOAD;	1092	our $AUTOLOAD;
495	our @ISA;	1093	our @ISA;
496		1094
497	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
498
499	our @REGISTRY;	1095	our @REGISTRY;
500		1096
		1097	our $WIN32;
		1098
		1099	our $VERBOSE;
		1100
		1101	BEGIN {
		1102	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		1103	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1104
		1105	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1106	if ${^TAINT};
		1107
		1108	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1109
		1110	}
		1111
		1112	our $MAX_SIGNAL_LATENCY = 10;
		1113
		1114	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		1115
		1116	{
		1117	my $idx;
		1118	$PROTOCOL{$_} = ++$idx
		1119	for reverse split /\s*,\s*/,
		1120	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		1121	}
		1122
501	my @models = (	1123	my @models = (
502	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
503	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
504	[EV:: => AnyEvent::Impl::EV::],	1124	[EV:: => AnyEvent::Impl::EV::],
505	[Event:: => AnyEvent::Impl::Event::],	1125	[Event:: => AnyEvent::Impl::Event::],
506	[Glib:: => AnyEvent::Impl::Glib::],	1126	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		1127	# everything below here will not be autoprobed
		1128	# as the pureperl backend should work everywhere
		1129	# and is usually faster
		1130	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1131	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
507	[Tk:: => AnyEvent::Impl::Tk::],	1132	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1133	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1134	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
508	[Wx:: => AnyEvent::Impl::POE::],	1135	[Wx:: => AnyEvent::Impl::POE::],
509	[Prima:: => AnyEvent::Impl::POE::],	1136	[Prima:: => AnyEvent::Impl::POE::],
510	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1137	# IO::Async is just too broken - we would need workarounds for its
511	# everything below here will not be autoprobed as the pureperl backend should work everywhere	1138	# byzantine signal and broken child handling, among others.
512	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1139	# IO::Async is rather hard to detect, as it doesn't have any
		1140	# obvious default class.
513	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1141	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
514	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1142	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1143	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
515	);	1144	);
516		1145
517	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	1146	our %method = map +($_ => 1),
		1147	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
		1148
		1149	our @post_detect;
		1150
		1151	sub post_detect(&) {
		1152	my ($cb) = @_;
		1153
		1154	if ($MODEL) {
		1155	$cb->();
		1156
		1157	1
		1158	} else {
		1159	push @post_detect, $cb;
		1160
		1161	defined wantarray
		1162	? bless \$cb, "AnyEvent::Util::postdetect"
		1163	: ()
		1164	}
		1165	}
		1166
		1167	sub AnyEvent::Util::postdetect::DESTROY {
		1168	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1169	}
518		1170
519	sub detect() {	1171	sub detect() {
520	unless ($MODEL) {	1172	unless ($MODEL) {
521	no strict 'refs';	1173	local $SIG{__DIE__};
522		1174
523	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1175	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
524	my $model = "AnyEvent::Impl::$1";	1176	my $model = "AnyEvent::Impl::$1";
525	if (eval "require $model") {	1177	if (eval "require $model") {
526	$MODEL = $model;	1178	$MODEL = $model;
527	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1179	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
528	} else {	1180	} else {
529	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1181	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
530	}	1182	}
531	}	1183	}
532		1184
533	# check for already loaded models	1185	# check for already loaded models
534	unless ($MODEL) {	1186	unless ($MODEL) {
535	for (@REGISTRY, @models) {	1187	for (@REGISTRY, @models) {
536	my ($package, $model) = @$_;	1188	my ($package, $model) = @$_;
537	if (${"$package\::VERSION"} > 0) {	1189	if (${"$package\::VERSION"} > 0) {
538	if (eval "require $model") {	1190	if (eval "require $model") {
539	$MODEL = $model;	1191	$MODEL = $model;
540	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1192	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
541	last;	1193	last;
542	}	1194	}
543	}	1195	}
544	}	1196	}
545		1197
…		…
550	my ($package, $model) = @$_;	1202	my ($package, $model) = @$_;
551	if (eval "require $package"	1203	if (eval "require $package"
552	and ${"$package\::VERSION"} > 0	1204	and ${"$package\::VERSION"} > 0
553	and eval "require $model") {	1205	and eval "require $model") {
554	$MODEL = $model;	1206	$MODEL = $model;
555	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1207	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
556	last;	1208	last;
557	}	1209	}
558	}	1210	}
559		1211
560	$MODEL	1212	$MODEL
561	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	1213	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
562	}	1214	}
563	}	1215	}
564		1216
		1217	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1218
565	unshift @ISA, $MODEL;	1219	unshift @ISA, $MODEL;
566	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1220
		1221	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1222
		1223	(shift @post_detect)->() while @post_detect;
567	}	1224	}
568		1225
569	$MODEL	1226	$MODEL
570	}	1227	}
571		1228
572	sub AUTOLOAD {	1229	sub AUTOLOAD {
573	(my $func = $AUTOLOAD) =~ s/.*://;	1230	(my $func = $AUTOLOAD) =~ s/.*://;
574		1231
575	$method{$func}	1232	$method{$func}
576	or croak "$func: not a valid method for AnyEvent objects";	1233	or Carp::croak "$func: not a valid method for AnyEvent objects";
577		1234
578	detect unless $MODEL;	1235	detect unless $MODEL;
579		1236
580	my $class = shift;	1237	my $class = shift;
581	$class->$func (@_);	1238	$class->$func (@_);
582	}	1239	}
583		1240
		1241	# utility function to dup a filehandle. this is used by many backends
		1242	# to support binding more than one watcher per filehandle (they usually
		1243	# allow only one watcher per fd, so we dup it to get a different one).
		1244	sub _dupfh($$;$$) {
		1245	my ($poll, $fh, $r, $w) = @_;
		1246
		1247	# cygwin requires the fh mode to be matching, unix doesn't
		1248	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1249
		1250	open my $fh2, $mode, $fh
		1251	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1252
		1253	# we assume CLOEXEC is already set by perl in all important cases
		1254
		1255	($fh2, $rw)
		1256	}
		1257
584	package AnyEvent::Base;	1258	package AnyEvent::Base;
585		1259
		1260	# default implementations for many methods
		1261
		1262	sub _time {
		1263	# probe for availability of Time::HiRes
		1264	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1265	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1266	*_time = \&Time::HiRes::time;
		1267	# if (eval "use POSIX (); (POSIX::times())...
		1268	} else {
		1269	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1270	*_time = sub { time }; # epic fail
		1271	}
		1272
		1273	&_time
		1274	}
		1275
		1276	sub time { _time }
		1277	sub now { _time }
		1278	sub now_update { }
		1279
586	# default implementation for ->condvar, ->wait, ->broadcast	1280	# default implementation for ->condvar
587		1281
588	sub condvar {	1282	sub condvar {
589	bless \my $flag, "AnyEvent::Base::CondVar"	1283	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
590	}
591
592	sub AnyEvent::Base::CondVar::broadcast {
593	${$_[0]}++;
594	}
595
596	sub AnyEvent::Base::CondVar::wait {
597	AnyEvent->one_event while !${$_[0]};
598	}	1284	}
599		1285
600	# default implementation for ->signal	1286	# default implementation for ->signal
601		1287
602	our %SIG_CB;	1288	our $HAVE_ASYNC_INTERRUPT;
		1289	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1290	our (%SIG_ASY, %SIG_ASY_W);
		1291	our ($SIG_COUNT, $SIG_TW);
603		1292
		1293	sub _signal_exec {
		1294	$HAVE_ASYNC_INTERRUPT
		1295	? $SIGPIPE_R->drain
		1296	: sysread $SIGPIPE_R, my $dummy, 9;
		1297
		1298	while (%SIG_EV) {
		1299	for (keys %SIG_EV) {
		1300	delete $SIG_EV{$_};
		1301	$_->() for values %{ $SIG_CB{$_} || {} };
		1302	}
		1303	}
		1304	}
		1305
		1306	# install a dumym wakeupw atcher to reduce signal catching latency
		1307	sub _sig_add() {
		1308	unless ($SIG_COUNT++) {
		1309	# try to align timer on a full-second boundary, if possible
		1310	my $NOW = AnyEvent->now;
		1311
		1312	$SIG_TW = AnyEvent->timer (
		1313	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1314	interval => $MAX_SIGNAL_LATENCY,
		1315	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1316	);
		1317	}
		1318	}
		1319
		1320	sub _sig_del {
		1321	undef $SIG_TW
		1322	unless --$SIG_COUNT;
		1323	}
		1324
604	sub signal {	1325	sub _signal {
605	my (undef, %arg) = @_;	1326	my (undef, %arg) = @_;
606		1327
607	my $signal = uc $arg{signal}	1328	my $signal = uc $arg{signal}
608	or Carp::croak "required option 'signal' is missing";	1329	or Carp::croak "required option 'signal' is missing";
609		1330
610	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1331	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1332
		1333	if ($HAVE_ASYNC_INTERRUPT) {
		1334	# async::interrupt
		1335
		1336	$SIG_ASY{$signal} ||= do {
		1337	my $asy = new Async::Interrupt
		1338	cb => sub { undef $SIG_EV{$signal} },
		1339	signal => $signal,
		1340	pipe => [$SIGPIPE_R->filenos],
		1341	;
		1342	$asy->pipe_autodrain (0);
		1343
		1344	$asy
		1345	};
		1346
		1347	} else {
		1348	# pure perl
		1349
611	$SIG{$signal} ||= sub {	1350	$SIG{$signal} ||= sub {
612	$_->() for values %{ $SIG_CB{$signal} || {} };	1351	local $!;
		1352	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1353	undef $SIG_EV{$signal};
		1354	};
		1355
		1356	# can't do signal processing without introducing races in pure perl,
		1357	# so limit the signal latency.
		1358	_sig_add;
613	};	1359	}
614		1360
615	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1361	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
616	}	1362	}
617		1363
		1364	sub signal {
		1365	# probe for availability of Async::Interrupt
		1366	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1367	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1368
		1369	$HAVE_ASYNC_INTERRUPT = 1;
		1370	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1371	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1372
		1373	} else {
		1374	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1375
		1376	require Fcntl;
		1377
		1378	if (AnyEvent::WIN32) {
		1379	require AnyEvent::Util;
		1380
		1381	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1382	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1383	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1384	} else {
		1385	pipe $SIGPIPE_R, $SIGPIPE_W;
		1386	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1387	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1388
		1389	# not strictly required, as $^F is normally 2, but let's make sure...
		1390	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1391	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1392	}
		1393
		1394	$SIGPIPE_R
		1395	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1396
		1397	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1398	}
		1399
		1400	*signal = \&_signal;
		1401	&signal
		1402	}
		1403
618	sub AnyEvent::Base::Signal::DESTROY {	1404	sub AnyEvent::Base::signal::DESTROY {
619	my ($signal, $cb) = @{$_[0]};	1405	my ($signal, $cb) = @{$_[0]};
620		1406
		1407	_sig_del;
		1408
621	delete $SIG_CB{$signal}{$cb};	1409	delete $SIG_CB{$signal}{$cb};
622		1410
623	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1411	$HAVE_ASYNC_INTERRUPT
		1412	? delete $SIG_ASY{$signal}
		1413	: # delete doesn't work with older perls - they then
		1414	# print weird messages, or just unconditionally exit
		1415	# instead of getting the default action.
		1416	undef $SIG{$signal}
		1417	unless keys %{ $SIG_CB{$signal} };
624	}	1418	}
625		1419
626	# default implementation for ->child	1420	# default implementation for ->child
627		1421
628	our %PID_CB;	1422	our %PID_CB;
629	our $CHLD_W;	1423	our $CHLD_W;
630	our $CHLD_DELAY_W;	1424	our $CHLD_DELAY_W;
631	our $PID_IDLE;
632	our $WNOHANG;	1425	our $WNOHANG;
633		1426
634	sub _child_wait {	1427	sub _sigchld {
635	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1428	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1429	$_->($pid, $?)
636	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1430	for values %{ $PID_CB{$pid} || {} },
637	(values %{ $PID_CB{0} || {} });	1431	values %{ $PID_CB{0} || {} };
638	}	1432	}
639
640	undef $PID_IDLE;
641	}
642
643	sub _sigchld {
644	# make sure we deliver these changes "synchronous" with the event loop.
645	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
646	undef $CHLD_DELAY_W;
647	&_child_wait;
648	});
649	}	1433	}
650		1434
651	sub child {	1435	sub child {
652	my (undef, %arg) = @_;	1436	my (undef, %arg) = @_;
653		1437
654	defined (my $pid = $arg{pid} + 0)	1438	defined (my $pid = $arg{pid} + 0)
655	or Carp::croak "required option 'pid' is missing";	1439	or Carp::croak "required option 'pid' is missing";
656		1440
657	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1441	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
658		1442
659	unless ($WNOHANG) {	1443	# WNOHANG is almost cetrainly 1 everywhere
660	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1444	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
661	}	1445	? 1
		1446	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
662		1447
663	unless ($CHLD_W) {	1448	unless ($CHLD_W) {
664	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1449	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
665	# child could be a zombie already, so make at least one round	1450	# child could be a zombie already, so make at least one round
666	&_sigchld;	1451	&_sigchld;
667	}	1452	}
668		1453
669	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1454	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
670	}	1455	}
671		1456
672	sub AnyEvent::Base::Child::DESTROY {	1457	sub AnyEvent::Base::child::DESTROY {
673	my ($pid, $cb) = @{$_[0]};	1458	my ($pid, $cb) = @{$_[0]};
674		1459
675	delete $PID_CB{$pid}{$cb};	1460	delete $PID_CB{$pid}{$cb};
676	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1461	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
677		1462
678	undef $CHLD_W unless keys %PID_CB;	1463	undef $CHLD_W unless keys %PID_CB;
679	}	1464	}
		1465
		1466	# idle emulation is done by simply using a timer, regardless
		1467	# of whether the process is idle or not, and not letting
		1468	# the callback use more than 50% of the time.
		1469	sub idle {
		1470	my (undef, %arg) = @_;
		1471
		1472	my ($cb, $w, $rcb) = $arg{cb};
		1473
		1474	$rcb = sub {
		1475	if ($cb) {
		1476	$w = _time;
		1477	&$cb;
		1478	$w = _time - $w;
		1479
		1480	# never use more then 50% of the time for the idle watcher,
		1481	# within some limits
		1482	$w = 0.0001 if $w < 0.0001;
		1483	$w = 5 if $w > 5;
		1484
		1485	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1486	} else {
		1487	# clean up...
		1488	undef $w;
		1489	undef $rcb;
		1490	}
		1491	};
		1492
		1493	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1494
		1495	bless \\$cb, "AnyEvent::Base::idle"
		1496	}
		1497
		1498	sub AnyEvent::Base::idle::DESTROY {
		1499	undef $${$_[0]};
		1500	}
		1501
		1502	package AnyEvent::CondVar;
		1503
		1504	our @ISA = AnyEvent::CondVar::Base::;
		1505
		1506	package AnyEvent::CondVar::Base;
		1507
		1508	#use overload
		1509	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1510	# fallback => 1;
		1511
		1512	# save 300+ kilobytes by dirtily hardcoding overloading
		1513	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1514	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1515	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1516	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1517
		1518	our $WAITING;
		1519
		1520	sub _send {
		1521	# nop
		1522	}
		1523
		1524	sub send {
		1525	my $cv = shift;
		1526	$cv->{_ae_sent} = [@_];
		1527	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1528	$cv->_send;
		1529	}
		1530
		1531	sub croak {
		1532	$_[0]{_ae_croak} = $_[1];
		1533	$_[0]->send;
		1534	}
		1535
		1536	sub ready {
		1537	$_[0]{_ae_sent}
		1538	}
		1539
		1540	sub _wait {
		1541	$WAITING
		1542	and !$_[0]{_ae_sent}
		1543	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1544
		1545	local $WAITING = 1;
		1546	AnyEvent->one_event while !$_[0]{_ae_sent};
		1547	}
		1548
		1549	sub recv {
		1550	$_[0]->_wait;
		1551
		1552	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1553	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1554	}
		1555
		1556	sub cb {
		1557	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1558	$_[0]{_ae_cb}
		1559	}
		1560
		1561	sub begin {
		1562	++$_[0]{_ae_counter};
		1563	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1564	}
		1565
		1566	sub end {
		1567	return if --$_[0]{_ae_counter};
		1568	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1569	}
		1570
		1571	# undocumented/compatibility with pre-3.4
		1572	*broadcast = \&send;
		1573	*wait = \&_wait;
		1574
		1575	=head1 ERROR AND EXCEPTION HANDLING
		1576
		1577	In general, AnyEvent does not do any error handling - it relies on the
		1578	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1579	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1580	checking of all AnyEvent methods, however, which is highly useful during
		1581	development.
		1582
		1583	As for exception handling (i.e. runtime errors and exceptions thrown while
		1584	executing a callback), this is not only highly event-loop specific, but
		1585	also not in any way wrapped by this module, as this is the job of the main
		1586	program.
		1587
		1588	The pure perl event loop simply re-throws the exception (usually
		1589	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1590	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1591	so on.
		1592
		1593	=head1 ENVIRONMENT VARIABLES
		1594
		1595	The following environment variables are used by this module or its
		1596	submodules.
		1597
		1598	Note that AnyEvent will remove I<all> environment variables starting with
		1599	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1600	enabled.
		1601
		1602	=over 4
		1603
		1604	=item C<PERL_ANYEVENT_VERBOSE>
		1605
		1606	By default, AnyEvent will be completely silent except in fatal
		1607	conditions. You can set this environment variable to make AnyEvent more
		1608	talkative.
		1609
		1610	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1611	conditions, such as not being able to load the event model specified by
		1612	C<PERL_ANYEVENT_MODEL>.
		1613
		1614	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1615	model it chooses.
		1616
		1617	When set to C<8> or higher, then AnyEvent will report extra information on
		1618	which optional modules it loads and how it implements certain features.
		1619
		1620	=item C<PERL_ANYEVENT_STRICT>
		1621
		1622	AnyEvent does not do much argument checking by default, as thorough
		1623	argument checking is very costly. Setting this variable to a true value
		1624	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1625	check the arguments passed to most method calls. If it finds any problems,
		1626	it will croak.
		1627
		1628	In other words, enables "strict" mode.
		1629
		1630	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1631	>>, it is definitely recommended to keep it off in production. Keeping
		1632	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1633	can be very useful, however.
		1634
		1635	=item C<PERL_ANYEVENT_MODEL>
		1636
		1637	This can be used to specify the event model to be used by AnyEvent, before
		1638	auto detection and -probing kicks in. It must be a string consisting
		1639	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1640	and the resulting module name is loaded and if the load was successful,
		1641	used as event model. If it fails to load AnyEvent will proceed with
		1642	auto detection and -probing.
		1643
		1644	This functionality might change in future versions.
		1645
		1646	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1647	could start your program like this:
		1648
		1649	PERL_ANYEVENT_MODEL=Perl perl ...
		1650
		1651	=item C<PERL_ANYEVENT_PROTOCOLS>
		1652
		1653	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1654	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1655	of auto probing).
		1656
		1657	Must be set to a comma-separated list of protocols or address families,
		1658	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1659	used, and preference will be given to protocols mentioned earlier in the
		1660	list.
		1661
		1662	This variable can effectively be used for denial-of-service attacks
		1663	against local programs (e.g. when setuid), although the impact is likely
		1664	small, as the program has to handle conenction and other failures anyways.
		1665
		1666	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1667	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1668	- only support IPv4, never try to resolve or contact IPv6
		1669	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1670	IPv6, but prefer IPv6 over IPv4.
		1671
		1672	=item C<PERL_ANYEVENT_EDNS0>
		1673
		1674	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1675	for DNS. This extension is generally useful to reduce DNS traffic, but
		1676	some (broken) firewalls drop such DNS packets, which is why it is off by
		1677	default.
		1678
		1679	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1680	EDNS0 in its DNS requests.
		1681
		1682	=item C<PERL_ANYEVENT_MAX_FORKS>
		1683
		1684	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1685	will create in parallel.
		1686
		1687	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1688
		1689	The default value for the C<max_outstanding> parameter for the default DNS
		1690	resolver - this is the maximum number of parallel DNS requests that are
		1691	sent to the DNS server.
		1692
		1693	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1694
		1695	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1696	configuration) in the default resolver. When set to the empty string, no
		1697	default config will be used.
		1698
		1699	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1700
		1701	When neither C<ca_file> nor C<ca_path> was specified during
		1702	L<AnyEvent::TLS> context creation, and either of these environment
		1703	variables exist, they will be used to specify CA certificate locations
		1704	instead of a system-dependent default.
		1705
		1706	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1707
		1708	When these are set to C<1>, then the respective modules are not
		1709	loaded. Mostly good for testing AnyEvent itself.
		1710
		1711	=back
680		1712
681	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1713	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
682		1714
683	This is an advanced topic that you do not normally need to use AnyEvent in	1715	This is an advanced topic that you do not normally need to use AnyEvent in
684	a module. This section is only of use to event loop authors who want to	1716	a module. This section is only of use to event loop authors who want to
…		…
718		1750
719	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1751	I<rxvt-unicode> also cheats a bit by not providing blocking access to
720	condition variables: code blocking while waiting for a condition will	1752	condition variables: code blocking while waiting for a condition will
721	C<die>. This still works with most modules/usages, and blocking calls must	1753	C<die>. This still works with most modules/usages, and blocking calls must
722	not be done in an interactive application, so it makes sense.	1754	not be done in an interactive application, so it makes sense.
723
724	=head1 ENVIRONMENT VARIABLES
725
726	The following environment variables are used by this module:
727
728	=over 4
729
730	=item C<PERL_ANYEVENT_VERBOSE>
731
732	By default, AnyEvent will be completely silent except in fatal
733	conditions. You can set this environment variable to make AnyEvent more
734	talkative.
735
736	When set to C<1> or higher, causes AnyEvent to warn about unexpected
737	conditions, such as not being able to load the event model specified by
738	C<PERL_ANYEVENT_MODEL>.
739
740	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
741	model it chooses.
742
743	=item C<PERL_ANYEVENT_MODEL>
744
745	This can be used to specify the event model to be used by AnyEvent, before
746	autodetection and -probing kicks in. It must be a string consisting
747	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
748	and the resulting module name is loaded and if the load was successful,
749	used as event model. If it fails to load AnyEvent will proceed with
750	autodetection and -probing.
751
752	This functionality might change in future versions.
753
754	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
755	could start your program like this:
756
757	PERL_ANYEVENT_MODEL=Perl perl ...
758
759	=back
760		1755
761	=head1 EXAMPLE PROGRAM	1756	=head1 EXAMPLE PROGRAM
762		1757
763	The following program uses an I/O watcher to read data from STDIN, a timer	1758	The following program uses an I/O watcher to read data from STDIN, a timer
764	to display a message once per second, and a condition variable to quit the	1759	to display a message once per second, and a condition variable to quit the
…		…
773	poll => 'r',	1768	poll => 'r',
774	cb => sub {	1769	cb => sub {
775	warn "io event <$_[0]>\n"; # will always output <r>	1770	warn "io event <$_[0]>\n"; # will always output <r>
776	chomp (my $input = <STDIN>); # read a line	1771	chomp (my $input = <STDIN>); # read a line
777	warn "read: $input\n"; # output what has been read	1772	warn "read: $input\n"; # output what has been read
778	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1773	$cv->send if $input =~ /^q/i; # quit program if /^q/i
779	},	1774	},
780	);	1775	);
781		1776
782	my $time_watcher; # can only be used once	1777	my $time_watcher; # can only be used once
783		1778
…		…
788	});	1783	});
789	}	1784	}
790		1785
791	new_timer; # create first timer	1786	new_timer; # create first timer
792		1787
793	$cv->wait; # wait until user enters /^q/i	1788	$cv->recv; # wait until user enters /^q/i
794		1789
795	=head1 REAL-WORLD EXAMPLE	1790	=head1 REAL-WORLD EXAMPLE
796		1791
797	Consider the L<Net::FCP> module. It features (among others) the following	1792	Consider the L<Net::FCP> module. It features (among others) the following
798	API calls, which are to freenet what HTTP GET requests are to http:	1793	API calls, which are to freenet what HTTP GET requests are to http:
…		…
848	syswrite $txn->{fh}, $txn->{request}	1843	syswrite $txn->{fh}, $txn->{request}
849	or die "connection or write error";	1844	or die "connection or write error";
850	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1845	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
851		1846
852	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1847	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
853	result and signals any possible waiters that the request ahs finished:	1848	result and signals any possible waiters that the request has finished:
854		1849
855	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1850	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
856		1851
857	if (end-of-file or data complete) {	1852	if (end-of-file or data complete) {
858	$txn->{result} = $txn->{buf};	1853	$txn->{result} = $txn->{buf};
859	$txn->{finished}->broadcast;	1854	$txn->{finished}->send;
860	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1855	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
861	}	1856	}
862		1857
863	The C<result> method, finally, just waits for the finished signal (if the	1858	The C<result> method, finally, just waits for the finished signal (if the
864	request was already finished, it doesn't wait, of course, and returns the	1859	request was already finished, it doesn't wait, of course, and returns the
865	data:	1860	data:
866		1861
867	$txn->{finished}->wait;	1862	$txn->{finished}->recv;
868	return $txn->{result};	1863	return $txn->{result};
869		1864
870	The actual code goes further and collects all errors (C<die>s, exceptions)	1865	The actual code goes further and collects all errors (C<die>s, exceptions)
871	that occured during request processing. The C<result> method detects	1866	that occurred during request processing. The C<result> method detects
872	whether an exception as thrown (it is stored inside the $txn object)	1867	whether an exception as thrown (it is stored inside the $txn object)
873	and just throws the exception, which means connection errors and other	1868	and just throws the exception, which means connection errors and other
874	problems get reported tot he code that tries to use the result, not in a	1869	problems get reported tot he code that tries to use the result, not in a
875	random callback.	1870	random callback.
876		1871
…		…
907		1902
908	my $quit = AnyEvent->condvar;	1903	my $quit = AnyEvent->condvar;
909		1904
910	$fcp->txn_client_get ($url)->cb (sub {	1905	$fcp->txn_client_get ($url)->cb (sub {
911	...	1906	...
912	$quit->broadcast;	1907	$quit->send;
913	});	1908	});
914		1909
915	$quit->wait;	1910	$quit->recv;
916		1911
917		1912
918	=head1 BENCHMARKS	1913	=head1 BENCHMARKS
919		1914
920	To give you an idea of the performance and overheads that AnyEvent adds	1915	To give you an idea of the performance and overheads that AnyEvent adds
…		…
922	of various event loops I prepared some benchmarks.	1917	of various event loops I prepared some benchmarks.
923		1918
924	=head2 BENCHMARKING ANYEVENT OVERHEAD	1919	=head2 BENCHMARKING ANYEVENT OVERHEAD
925		1920
926	Here is a benchmark of various supported event models used natively and	1921	Here is a benchmark of various supported event models used natively and
927	through anyevent. The benchmark creates a lot of timers (with a zero	1922	through AnyEvent. The benchmark creates a lot of timers (with a zero
928	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1923	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
929	which it is), lets them fire exactly once and destroys them again.	1924	which it is), lets them fire exactly once and destroys them again.
930		1925
931	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1926	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
932	distribution.	1927	distribution.
…		…
949	all watchers, to avoid adding memory overhead. That means closure creation	1944	all watchers, to avoid adding memory overhead. That means closure creation
950	and memory usage is not included in the figures.	1945	and memory usage is not included in the figures.
951		1946
952	I<invoke> is the time, in microseconds, used to invoke a simple	1947	I<invoke> is the time, in microseconds, used to invoke a simple
953	callback. The callback simply counts down a Perl variable and after it was	1948	callback. The callback simply counts down a Perl variable and after it was
954	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1949	invoked "watcher" times, it would C<< ->send >> a condvar once to
955	signal the end of this phase.	1950	signal the end of this phase.
956		1951
957	I<destroy> is the time, in microseconds, that it takes to destroy a single	1952	I<destroy> is the time, in microseconds, that it takes to destroy a single
958	watcher.	1953	watcher.
959		1954
960	=head3 Results	1955	=head3 Results
961		1956
962	name watchers bytes create invoke destroy comment	1957	name watchers bytes create invoke destroy comment
963	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1958	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
964	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1959	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
965	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1960	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
966	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1961	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
967	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1962	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
968	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1963	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1964	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1965	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
969	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1966	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
970	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1967	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
971	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1968	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
972	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1969	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
973		1970
974	=head3 Discussion	1971	=head3 Discussion
975		1972
976	The benchmark does I<not> measure scalability of the event loop very	1973	The benchmark does I<not> measure scalability of the event loop very
977	well. For example, a select-based event loop (such as the pure perl one)	1974	well. For example, a select-based event loop (such as the pure perl one)
…		…
1002	performance becomes really bad with lots of file descriptors (and few of	1999	performance becomes really bad with lots of file descriptors (and few of
1003	them active), of course, but this was not subject of this benchmark.	2000	them active), of course, but this was not subject of this benchmark.
1004		2001
1005	The C<Event> module has a relatively high setup and callback invocation	2002	The C<Event> module has a relatively high setup and callback invocation
1006	cost, but overall scores in on the third place.	2003	cost, but overall scores in on the third place.
		2004
		2005	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2006	when using its pure perl backend.
1007		2007
1008	C<Glib>'s memory usage is quite a bit higher, but it features a	2008	C<Glib>'s memory usage is quite a bit higher, but it features a
1009	faster callback invocation and overall ends up in the same class as	2009	faster callback invocation and overall ends up in the same class as
1010	C<Event>. However, Glib scales extremely badly, doubling the number of	2010	C<Event>. However, Glib scales extremely badly, doubling the number of
1011	watchers increases the processing time by more than a factor of four,	2011	watchers increases the processing time by more than a factor of four,
…		…
1019	file descriptor is dup()ed for each watcher. This shows that the dup()	2019	file descriptor is dup()ed for each watcher. This shows that the dup()
1020	employed by some adaptors is not a big performance issue (it does incur a	2020	employed by some adaptors is not a big performance issue (it does incur a
1021	hidden memory cost inside the kernel which is not reflected in the figures	2021	hidden memory cost inside the kernel which is not reflected in the figures
1022	above).	2022	above).
1023		2023
1024	C<POE>, regardless of underlying event loop (whether using its pure	2024	C<POE>, regardless of underlying event loop (whether using its pure perl
1025	perl select-based backend or the Event module, the POE-EV backend	2025	select-based backend or the Event module, the POE-EV backend couldn't
1026	couldn't be tested because it wasn't working) shows abysmal performance	2026	be tested because it wasn't working) shows abysmal performance and
1027	and memory usage: Watchers use almost 30 times as much memory as	2027	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1028	EV watchers, and 10 times as much memory as Event (the high memory	2028	as EV watchers, and 10 times as much memory as Event (the high memory
1029	requirements are caused by requiring a session for each watcher). Watcher	2029	requirements are caused by requiring a session for each watcher). Watcher
1030	invocation speed is almost 900 times slower than with AnyEvent's pure perl	2030	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		2031	implementation.
		2032
1031	implementation. The design of the POE adaptor class in AnyEvent can not	2033	The design of the POE adaptor class in AnyEvent can not really account
1032	really account for this, as session creation overhead is small compared	2034	for the performance issues, though, as session creation overhead is
1033	to execution of the state machine, which is coded pretty optimally within	2035	small compared to execution of the state machine, which is coded pretty
1034	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	2036	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		2037	using multiple sessions is not a good approach, especially regarding
		2038	memory usage, even the author of POE could not come up with a faster
		2039	design).
1035		2040
1036	=head3 Summary	2041	=head3 Summary
1037		2042
1038	=over 4	2043	=over 4
1039		2044
…		…
1050		2055
1051	=back	2056	=back
1052		2057
1053	=head2 BENCHMARKING THE LARGE SERVER CASE	2058	=head2 BENCHMARKING THE LARGE SERVER CASE
1054		2059
1055	This benchmark atcually benchmarks the event loop itself. It works by	2060	This benchmark actually benchmarks the event loop itself. It works by
1056	creating a number of "servers": each server consists of a socketpair, a	2061	creating a number of "servers": each server consists of a socket pair, a
1057	timeout watcher that gets reset on activity (but never fires), and an I/O	2062	timeout watcher that gets reset on activity (but never fires), and an I/O
1058	watcher waiting for input on one side of the socket. Each time the socket	2063	watcher waiting for input on one side of the socket. Each time the socket
1059	watcher reads a byte it will write that byte to a random other "server".	2064	watcher reads a byte it will write that byte to a random other "server".
1060		2065
1061	The effect is that there will be a lot of I/O watchers, only part of which	2066	The effect is that there will be a lot of I/O watchers, only part of which
1062	are active at any one point (so there is a constant number of active	2067	are active at any one point (so there is a constant number of active
1063	fds for each loop iterstaion, but which fds these are is random). The	2068	fds for each loop iteration, but which fds these are is random). The
1064	timeout is reset each time something is read because that reflects how	2069	timeout is reset each time something is read because that reflects how
1065	most timeouts work (and puts extra pressure on the event loops).	2070	most timeouts work (and puts extra pressure on the event loops).
1066		2071
1067	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	2072	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1068	(1%) are active. This mirrors the activity of large servers with many	2073	(1%) are active. This mirrors the activity of large servers with many
1069	connections, most of which are idle at any one point in time.	2074	connections, most of which are idle at any one point in time.
1070		2075
1071	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2076	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1072	distribution.	2077	distribution.
…		…
1074	=head3 Explanation of the columns	2079	=head3 Explanation of the columns
1075		2080
1076	I<sockets> is the number of sockets, and twice the number of "servers" (as	2081	I<sockets> is the number of sockets, and twice the number of "servers" (as
1077	each server has a read and write socket end).	2082	each server has a read and write socket end).
1078		2083
1079	I<create> is the time it takes to create a socketpair (which is	2084	I<create> is the time it takes to create a socket pair (which is
1080	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	2085	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1081		2086
1082	I<request>, the most important value, is the time it takes to handle a	2087	I<request>, the most important value, is the time it takes to handle a
1083	single "request", that is, reading the token from the pipe and forwarding	2088	single "request", that is, reading the token from the pipe and forwarding
1084	it to another server. This includes deleting the old timeout and creating	2089	it to another server. This includes deleting the old timeout and creating
1085	a new one that moves the timeout into the future.	2090	a new one that moves the timeout into the future.
1086		2091
1087	=head3 Results	2092	=head3 Results
1088		2093
1089	name sockets create request	2094	name sockets create request
1090	EV 20000 69.01 11.16	2095	EV 20000 69.01 11.16
1091	Perl 20000 75.28 112.76	2096	Perl 20000 73.32 35.87
		2097	IOAsync 20000 157.00 98.14 epoll
		2098	IOAsync 20000 159.31 616.06 poll
1092	Event 20000 212.62 257.32	2099	Event 20000 212.62 257.32
1093	Glib 20000 651.16 1896.30	2100	Glib 20000 651.16 1896.30
1094	POE 20000 349.67 12317.24 uses POE::Loop::Event	2101	POE 20000 349.67 12317.24 uses POE::Loop::Event
1095		2102
1096	=head3 Discussion	2103	=head3 Discussion
1097		2104
1098	This benchmark I<does> measure scalability and overall performance of the	2105	This benchmark I<does> measure scalability and overall performance of the
1099	particular event loop.	2106	particular event loop.
…		…
1101	EV is again fastest. Since it is using epoll on my system, the setup time	2108	EV is again fastest. Since it is using epoll on my system, the setup time
1102	is relatively high, though.	2109	is relatively high, though.
1103		2110
1104	Perl surprisingly comes second. It is much faster than the C-based event	2111	Perl surprisingly comes second. It is much faster than the C-based event
1105	loops Event and Glib.	2112	loops Event and Glib.
		2113
		2114	IO::Async performs very well when using its epoll backend, and still quite
		2115	good compared to Glib when using its pure perl backend.
1106		2116
1107	Event suffers from high setup time as well (look at its code and you will	2117	Event suffers from high setup time as well (look at its code and you will
1108	understand why). Callback invocation also has a high overhead compared to	2118	understand why). Callback invocation also has a high overhead compared to
1109	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2119	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1110	uses select or poll in basically all documented configurations.	2120	uses select or poll in basically all documented configurations.
…		…
1118		2128
1119	=head3 Summary	2129	=head3 Summary
1120		2130
1121	=over 4	2131	=over 4
1122		2132
1123	=item * The pure perl implementation performs extremely well, considering	2133	=item * The pure perl implementation performs extremely well.
1124	that it uses select.
1125		2134
1126	=item * Avoid Glib or POE in large projects where performance matters.	2135	=item * Avoid Glib or POE in large projects where performance matters.
1127		2136
1128	=back	2137	=back
1129		2138
…		…
1142		2151
1143	=head3 Results	2152	=head3 Results
1144		2153
1145	name sockets create request	2154	name sockets create request
1146	EV 16 20.00 6.54	2155	EV 16 20.00 6.54
		2156	Perl 16 25.75 12.62
1147	Event 16 81.27 35.86	2157	Event 16 81.27 35.86
1148	Glib 16 32.63 15.48	2158	Glib 16 32.63 15.48
1149	Perl 16 24.62 162.37
1150	POE 16 261.87 276.28 uses POE::Loop::Event	2159	POE 16 261.87 276.28 uses POE::Loop::Event
1151		2160
1152	=head3 Discussion	2161	=head3 Discussion
1153		2162
1154	The benchmark tries to test the performance of a typical small	2163	The benchmark tries to test the performance of a typical small
…		…
1158	speed most when you have lots of watchers, not when you only have a few of	2167	speed most when you have lots of watchers, not when you only have a few of
1159	them).	2168	them).
1160		2169
1161	EV is again fastest.	2170	EV is again fastest.
1162		2171
1163	The C-based event loops Event and Glib come in second this time, as the	2172	Perl again comes second. It is noticeably faster than the C-based event
1164	overhead of running an iteration is much smaller in C than in Perl (little	2173	loops Event and Glib, although the difference is too small to really
1165	code to execute in the inner loop, and perl's function calling overhead is	2174	matter.
1166	high, and updating all the data structures is costly).
1167
1168	The pure perl event loop is much slower, but still competitive.
1169		2175
1170	POE also performs much better in this case, but is is still far behind the	2176	POE also performs much better in this case, but is is still far behind the
1171	others.	2177	others.
1172		2178
1173	=head3 Summary	2179	=head3 Summary
…		…
1177	=item * C-based event loops perform very well with small number of	2183	=item * C-based event loops perform very well with small number of
1178	watchers, as the management overhead dominates.	2184	watchers, as the management overhead dominates.
1179		2185
1180	=back	2186	=back
1181		2187
		2188	=head2 THE IO::Lambda BENCHMARK
		2189
		2190	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2191	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2192	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2193	shouldn't come as a surprise to anybody). As such, the benchmark is
		2194	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2195	very optimal. But how would AnyEvent compare when used without the extra
		2196	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2197
		2198	The benchmark itself creates an echo-server, and then, for 500 times,
		2199	connects to the echo server, sends a line, waits for the reply, and then
		2200	creates the next connection. This is a rather bad benchmark, as it doesn't
		2201	test the efficiency of the framework or much non-blocking I/O, but it is a
		2202	benchmark nevertheless.
		2203
		2204	name runtime
		2205	Lambda/select 0.330 sec
		2206	+ optimized 0.122 sec
		2207	Lambda/AnyEvent 0.327 sec
		2208	+ optimized 0.138 sec
		2209	Raw sockets/select 0.077 sec
		2210	POE/select, components 0.662 sec
		2211	POE/select, raw sockets 0.226 sec
		2212	POE/select, optimized 0.404 sec
		2213
		2214	AnyEvent/select/nb 0.085 sec
		2215	AnyEvent/EV/nb 0.068 sec
		2216	+state machine 0.134 sec
		2217
		2218	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2219	benchmarks actually make blocking connects and use 100% blocking I/O,
		2220	defeating the purpose of an event-based solution. All of the newly
		2221	written AnyEvent benchmarks use 100% non-blocking connects (using
		2222	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2223	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2224	generally require a lot more bookkeeping and event handling than blocking
		2225	connects (which involve a single syscall only).
		2226
		2227	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2228	offers similar expressive power as POE and IO::Lambda, using conventional
		2229	Perl syntax. This means that both the echo server and the client are 100%
		2230	non-blocking, further placing it at a disadvantage.
		2231
		2232	As you can see, the AnyEvent + EV combination even beats the
		2233	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2234	backend easily beats IO::Lambda and POE.
		2235
		2236	And even the 100% non-blocking version written using the high-level (and
		2237	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2238	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2239	in a non-blocking way.
		2240
		2241	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2242	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2243	part of the IO::lambda distribution and were used without any changes.
		2244
		2245
		2246	=head1 SIGNALS
		2247
		2248	AnyEvent currently installs handlers for these signals:
		2249
		2250	=over 4
		2251
		2252	=item SIGCHLD
		2253
		2254	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2255	emulation for event loops that do not support them natively. Also, some
		2256	event loops install a similar handler.
		2257
		2258	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2259	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2260
		2261	=item SIGPIPE
		2262
		2263	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2264	when AnyEvent gets loaded.
		2265
		2266	The rationale for this is that AnyEvent users usually do not really depend
		2267	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2268	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2269	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2270	some random socket.
		2271
		2272	The rationale for installing a no-op handler as opposed to ignoring it is
		2273	that this way, the handler will be restored to defaults on exec.
		2274
		2275	Feel free to install your own handler, or reset it to defaults.
		2276
		2277	=back
		2278
		2279	=cut
		2280
		2281	undef $SIG{CHLD}
		2282	if $SIG{CHLD} eq 'IGNORE';
		2283
		2284	$SIG{PIPE} = sub { }
		2285	unless defined $SIG{PIPE};
		2286
		2287	=head1 RECOMMENDED/OPTIONAL MODULES
		2288
		2289	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2290	it's built-in modules) are required to use it.
		2291
		2292	That does not mean that AnyEvent won't take advantage of some additional
		2293	modules if they are installed.
		2294
		2295	This section epxlains which additional modules will be used, and how they
		2296	affect AnyEvent's operetion.
		2297
		2298	=over 4
		2299
		2300	=item L<Async::Interrupt>
		2301
		2302	This slightly arcane module is used to implement fast signal handling: To
		2303	my knowledge, there is no way to do completely race-free and quick
		2304	signal handling in pure perl. To ensure that signals still get
		2305	delivered, AnyEvent will start an interval timer to wake up perl (and
		2306	catch the signals) with some delay (default is 10 seconds, look for
		2307	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2308
		2309	If this module is available, then it will be used to implement signal
		2310	catching, which means that signals will not be delayed, and the event loop
		2311	will not be interrupted regularly, which is more efficient (And good for
		2312	battery life on laptops).
		2313
		2314	This affects not just the pure-perl event loop, but also other event loops
		2315	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2316
		2317	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2318	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2319	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2320	does nothing for those backends.
		2321
		2322	=item L<EV>
		2323
		2324	This module isn't really "optional", as it is simply one of the backend
		2325	event loops that AnyEvent can use. However, it is simply the best event
		2326	loop available in terms of features, speed and stability: It supports
		2327	the AnyEvent API optimally, implements all the watcher types in XS, does
		2328	automatic timer adjustments even when no monotonic clock is available,
		2329	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2330	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2331	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2332
		2333	=item L<Guard>
		2334
		2335	The guard module, when used, will be used to implement
		2336	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2337	lot less memory), but otherwise doesn't affect guard operation much. It is
		2338	purely used for performance.
		2339
		2340	=item L<JSON> and L<JSON::XS>
		2341
		2342	This module is required when you want to read or write JSON data via
		2343	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2344	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2345
		2346	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2347	installed.
		2348
		2349	=item L<Net::SSLeay>
		2350
		2351	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2352	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2353	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2354
		2355	=item L<Time::HiRes>
		2356
		2357	This module is part of perl since release 5.008. It will be used when the
		2358	chosen event library does not come with a timing source on it's own. The
		2359	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2360	try to use a monotonic clock for timing stability.
		2361
		2362	=back
		2363
1182		2364
1183	=head1 FORK	2365	=head1 FORK
1184		2366
1185	Most event libraries are not fork-safe. The ones who are usually are	2367	Most event libraries are not fork-safe. The ones who are usually are
1186	because they are so inefficient. Only L<EV> is fully fork-aware.	2368	because they rely on inefficient but fork-safe C<select> or C<poll>
		2369	calls. Only L<EV> is fully fork-aware.
1187		2370
1188	If you have to fork, you must either do so I<before> creating your first	2371	If you have to fork, you must either do so I<before> creating your first
1189	watcher OR you must not use AnyEvent at all in the child.	2372	watcher OR you must not use AnyEvent at all in the child OR you must do
		2373	something completely out of the scope of AnyEvent.
1190		2374
1191		2375
1192	=head1 SECURITY CONSIDERATIONS	2376	=head1 SECURITY CONSIDERATIONS
1193		2377
1194	AnyEvent can be forced to load any event model via	2378	AnyEvent can be forced to load any event model via
…		…
1199	specified in the variable.	2383	specified in the variable.
1200		2384
1201	You can make AnyEvent completely ignore this variable by deleting it	2385	You can make AnyEvent completely ignore this variable by deleting it
1202	before the first watcher gets created, e.g. with a C<BEGIN> block:	2386	before the first watcher gets created, e.g. with a C<BEGIN> block:
1203		2387
1204	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2388	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1205		2389
1206	use AnyEvent;	2390	use AnyEvent;
		2391
		2392	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		2393	be used to probe what backend is used and gain other information (which is
		2394	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2395	$ENV{PERL_ANYEVENT_STRICT}.
		2396
		2397	Note that AnyEvent will remove I<all> environment variables starting with
		2398	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2399	enabled.
		2400
		2401
		2402	=head1 BUGS
		2403
		2404	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2405	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2406	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2407	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2408	pronounced).
1207		2409
1208		2410
1209	=head1 SEE ALSO	2411	=head1 SEE ALSO
1210		2412
1211	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	2413	Utility functions: L<AnyEvent::Util>.
1212	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	2414
		2415	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1213	L<Event::Lib>, L<Qt>, L<POE>.	2416	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1214		2417
1215	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	2418	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1216	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	2419	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1217	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	2420	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1218	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	2421	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1219		2422
		2423	Non-blocking file handles, sockets, TCP clients and
		2424	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
		2425
		2426	Asynchronous DNS: L<AnyEvent::DNS>.
		2427
		2428	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2429	L<Coro::Event>,
		2430
1220	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	2431	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2432	L<AnyEvent::HTTP>.
1221		2433
1222		2434
1223	=head1 AUTHOR	2435	=head1 AUTHOR
1224		2436
1225	Marc Lehmann <schmorp@schmorp.de>	2437	Marc Lehmann <schmorp@schmorp.de>
1226	http://home.schmorp.de/	2438	http://home.schmorp.de/
1227		2439
1228	=cut	2440	=cut
1229		2441
1230	1	2442	1
1231		2443

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