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Revision 1.83 by root, Fri Apr 25 13:39:08 2008 UTC vs.
Revision 1.250 by root, Mon Jul 20 07:12:38 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		108
72	=head1 DESCRIPTION	109	=head1 DESCRIPTION
73		110
74	L<AnyEvent> provides an identical interface to multiple event loops. This	111	L<AnyEvent> provides an identical interface to multiple event loops. This
75	allows module authors to utilise an event loop without forcing module	112	allows module authors to utilise an event loop without forcing module
…		…
79	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>
80	module.	117	module.
81		118
82	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
83	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
84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	121	following modules is already loaded: L<EV>,
85	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>,
86	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
87	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
88	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
89	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
…		…
103	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
104	use AnyEvent so their modules work together with others seamlessly...	141	use AnyEvent so their modules work together with others seamlessly...
105		142
106	The pure-perl implementation of AnyEvent is called	143	The pure-perl implementation of AnyEvent is called
107	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
108	explicitly.	145	explicitly and enjoy the high availability of that event loop :)
109		146
110	=head1 WATCHERS	147	=head1 WATCHERS
111		148
112	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
113	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
114	the callback to call, the filehandle to watch, etc.	151	the callback to call, the file handle to watch, etc.
115		152
116	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
117	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
118	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
119	is in control).	156	is in control).
120		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
121	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
122	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
123	to it).	166	to it).
124		167
125	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.
…		…
127	Many watchers either are used with "recursion" (repeating timers for	170	Many watchers either are used with "recursion" (repeating timers for
128	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.
129		172
130	An any way to achieve that is this pattern:	173	An any way to achieve that is this pattern:
131		174
132	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	175	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
133	# you can use $w here, for example to undef it	176	# you can use $w here, for example to undef it
134	undef $w;	177	undef $w;
135	});	178	});
136		179
137	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,
138	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
139	declared.	182	declared.
140		183
141	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
142		185
143	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
144	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
145		188
146	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for	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
147	events. C<poll> must be a string that is either C<r> or C<w>, which	196	C<poll> must be a string that is either C<r> or C<w>, which creates a
148	creates a watcher waiting for "r"eadable or "w"ritable events,	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
149	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.
150	becomes ready.	200
		201	Although the callback might get passed parameters, their value and
		202	presence is undefined and you cannot rely on them. Portable AnyEvent
		203	callbacks cannot use arguments passed to I/O watcher callbacks.
151		204
152	The I/O watcher might use the underlying file descriptor or a copy of it.	205	The I/O watcher might use the underlying file descriptor or a copy of it.
153	It is not allowed to close a file handle as long as any watcher is active	206	You must not close a file handle as long as any watcher is active on the
154	on the underlying file descriptor.	207	underlying file descriptor.
155		208
156	Some event loops issue spurious readyness notifications, so you should	209	Some event loops issue spurious readyness notifications, so you should
157	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
158	handles.	211	handles.
159		212
160	Example:
161
162	# 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
163	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	216	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
164	chomp (my $input = <STDIN>);	217	chomp (my $input = <STDIN>);
165	warn "read: $input\n";	218	warn "read: $input\n";
166	undef $w;	219	undef $w;
167	});	220	});
…		…
170		223
171	You can create a time watcher by calling the C<< AnyEvent->timer >>	224	You can create a time watcher by calling the C<< AnyEvent->timer >>
172	method with the following mandatory arguments:	225	method with the following mandatory arguments:
173		226
174	C<after> specifies after how many seconds (fractional values are	227	C<after> specifies after how many seconds (fractional values are
175	supported) should the timer activate. C<cb> the callback to invoke in that	228	supported) the callback should be invoked. C<cb> is the callback to invoke
176	case.	229	in that case.
177		230
178	The timer callback will be invoked at most once: if you want a repeating	231	Although the callback might get passed parameters, their value and
179	timer you have to create a new watcher (this is a limitation by both Tk	232	presence is undefined and you cannot rely on them. Portable AnyEvent
180	and Glib).	233	callbacks cannot use arguments passed to time watcher callbacks.
181		234
182	Example:	235	The callback will normally be invoked once only. If you specify another
		236	parameter, C<interval>, as a strictly positive number (> 0), then the
		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.
183		240
		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.
		244
184	# fire an event after 7.7 seconds	245	Example: fire an event after 7.7 seconds.
		246
185	my $w = AnyEvent->timer (after => 7.7, cb => sub {	247	my $w = AnyEvent->timer (after => 7.7, cb => sub {
186	warn "timeout\n";	248	warn "timeout\n";
187	});	249	});
188		250
189	# to cancel the timer:	251	# to cancel the timer:
190	undef $w;	252	undef $w;
191		253
192	Example 2:
193
194	# 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.
195	my $w;
196		255
197	my $cb = sub {
198	# cancel the old timer while creating a new one
199	$w = AnyEvent->timer (after => 1, cb => $cb);	256	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		257	warn "timeout\n";
200	};	258	};
201
202	# start the "loop" by creating the first watcher
203	$w = AnyEvent->timer (after => 0.5, cb => $cb);
204		259
205	=head3 TIMING ISSUES	260	=head3 TIMING ISSUES
206		261
207	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
208	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
…		…
220	timers.	275	timers.
221		276
222	AnyEvent always prefers relative timers, if available, matching the	277	AnyEvent always prefers relative timers, if available, matching the
223	AnyEvent API.	278	AnyEvent API.
224		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
225	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
226		359
227	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
228	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
229	be invoked whenever a signal occurs.	362	callback to be invoked whenever a signal occurs.
230		363
		364	Although the callback might get passed parameters, their value and
		365	presence is undefined and you cannot rely on them. Portable AnyEvent
		366	callbacks cannot use arguments passed to signal watcher callbacks.
		367
231	Multiple signal occurances can be clumped together into one callback	368	Multiple signal occurrences can be clumped together into one callback
232	invocation, and callback invocation will be synchronous. synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
233	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,
234	but it is guarenteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
235		372
236	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
237	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
238		376
239	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
240	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
241		380
242	Example: exit on SIGINT	381	Example: exit on SIGINT
243		382
244	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
245		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$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
246	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
247		402
248	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.
249		404
250	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
251	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
252	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
253	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	any trace events (stopped/continued).
254	and exit status (as returned by waitpid).	409
		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).
255		418
256	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
257	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
258	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
259		422
260	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
261	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
262	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.
263		429
264	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
265	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
266	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.
267		438
268	Example: fork a process and wait for it	439	Example: fork a process and wait for it
269		440
270	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
271		442
272	AnyEvent::detect; # force event module to be initialised
273
274	my $pid = fork or exit 5;	443	my $pid = fork or exit 5;
275		444
276	my $w = AnyEvent->child (	445	my $w = AnyEvent->child (
277	pid => $pid,	446	pid => $pid,
278	cb => sub {	447	cb => sub {
279	my ($pid, $status) = @_;	448	my ($pid, $status) = @_;
280	warn "pid $pid exited with status $status";	449	warn "pid $pid exited with status $status";
281	$done->broadcast;	450	$done->send;
282	},	451	},
283	);	452	);
284		453
285	# do something else, then wait for process exit	454	# do something else, then wait for process exit
286	$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	});
287		491
288	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
289		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
290	Condition variables can be created by calling the C<< AnyEvent->condvar >>	506	Condition variables can be created by calling the C<< AnyEvent->condvar
291	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).
292		511
293	A condition variable waits for a condition - precisely that the C<<	512	After creation, the condition variable is "false" until it becomes "true"
294	->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).
295		516
296	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,
297	example, if you write a module that does asynchronous http requests,	526	for example, if you write a module that does asynchronous http requests,
298	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
299	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.
300		530
301	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,
302	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
303	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
304	->broadcast >> the "quit" event.	534	button of your app, which would C<< ->send >> the "quit" event.
305		535
306	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
307	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
308	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
309	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,
310	as this asks for trouble.	540	as this asks for trouble.
311		541
312	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.
313		547
314	=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.
315		551
316	=item $cv->wait	552	Example: wait for a timer.
317
318	Wait (blocking if necessary) until the C<< ->broadcast >> method has been
319	called on c<$cv>, while servicing other watchers normally.
320
321	You can only wait once on a condition - additional calls will return
322	immediately.
323
324	Not all event models support a blocking wait - some die in that case
325	(programs might want to do that to stay interactive), so I<if you are
326	using this from a module, never require a blocking wait>, but let the
327	caller decide whether the call will block or not (for example, by coupling
328	condition variables with some kind of request results and supporting
329	callbacks so the caller knows that getting the result will not block,
330	while still suppporting blocking waits if the caller so desires).
331
332	Another reason I<never> to C<< ->wait >> in a module is that you cannot
333	sensibly have two C<< ->wait >>'s in parallel, as that would require
334	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
335	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
336	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
337	from different coroutines, however).
338
339	=item $cv->broadcast
340
341	Flag the condition as ready - a running C<< ->wait >> and all further
342	calls to C<wait> will (eventually) return after this method has been
343	called. If nobody is waiting the broadcast will be remembered..
344
345	=back
346
347	Example:
348		553
349	# wait till the result is ready	554	# wait till the result is ready
350	my $result_ready = AnyEvent->condvar;	555	my $result_ready = AnyEvent->condvar;
351		556
352	# do something such as adding a timer	557	# do something such as adding a timer
353	# or socket watcher the calls $result_ready->broadcast	558	# or socket watcher the calls $result_ready->send
354	# when the "result" is ready.	559	# when the "result" is ready.
355	# in this case, we simply use a timer:	560	# in this case, we simply use a timer:
356	my $w = AnyEvent->timer (	561	my $w = AnyEvent->timer (
357	after => 1,	562	after => 1,
358	cb => sub { $result_ready->broadcast },	563	cb => sub { $result_ready->send },
359	);	564	);
360		565
361	# this "blocks" (while handling events) till the watcher	566	# this "blocks" (while handling events) till the callback
362	# calls broadcast	567	# calls -<send
363	$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
364		838
365	=head1 GLOBAL VARIABLES AND FUNCTIONS	839	=head1 GLOBAL VARIABLES AND FUNCTIONS
366		840
		841	These are not normally required to use AnyEvent, but can be useful to
		842	write AnyEvent extension modules.
		843
367	=over 4	844	=over 4
368		845
369	=item $AnyEvent::MODEL	846	=item $AnyEvent::MODEL
370		847
371	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
372	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
373	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
374	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
375	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
376		855	will be C<urxvt::anyevent>).
377	The known classes so far are:
378
379	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
380	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
381	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
382	AnyEvent::Impl::Event based on Event, second best choice.
383	AnyEvent::Impl::Glib based on Glib, third-best choice.
384	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
385	AnyEvent::Impl::Tk based on Tk, very bad choice.
386	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
387	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
388	AnyEvent::Impl::POE based on POE, not generic enough for full support.
389
390	There is no support for WxWidgets, as WxWidgets has no support for
391	watching file handles. However, you can use WxWidgets through the
392	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
393	second, which was considered to be too horrible to even consider for
394	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
395	it's adaptor.
396
397	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
398	autodetecting them.
399		856
400	=item AnyEvent::detect	857	=item AnyEvent::detect
401		858
402	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	859	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
403	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
404	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
405	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. See
		885	L<Coro::BDB> for a case where this is useful.
		886
		887	=item @AnyEvent::post_detect
		888
		889	If there are any code references in this array (you can C<push> to it
		890	before or after loading AnyEvent), then they will called directly after
		891	the event loop has been chosen.
		892
		893	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		894	if it is defined then the event loop has already been detected, and the
		895	array will be ignored.
		896
		897	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		898	it,as it takes care of these details.
		899
		900	This variable is mainly useful for modules that can do something useful
		901	when AnyEvent is used and thus want to know when it is initialised, but do
		902	not need to even load it by default. This array provides the means to hook
		903	into AnyEvent passively, without loading it.
406		904
407	=back	905	=back
408		906
409	=head1 WHAT TO DO IN A MODULE	907	=head1 WHAT TO DO IN A MODULE
410		908
…		…
414	Be careful when you create watchers in the module body - AnyEvent will	912	Be careful when you create watchers in the module body - AnyEvent will
415	decide which event module to use as soon as the first method is called, so	913	decide which event module to use as soon as the first method is called, so
416	by calling AnyEvent in your module body you force the user of your module	914	by calling AnyEvent in your module body you force the user of your module
417	to load the event module first.	915	to load the event module first.
418		916
419	Never call C<< ->wait >> on a condition variable unless you I<know> that	917	Never call C<< ->recv >> on a condition variable unless you I<know> that
420	the C<< ->broadcast >> method has been called on it already. This is	918	the C<< ->send >> method has been called on it already. This is
421	because it will stall the whole program, and the whole point of using	919	because it will stall the whole program, and the whole point of using
422	events is to stay interactive.	920	events is to stay interactive.
423		921
424	It is fine, however, to call C<< ->wait >> when the user of your module	922	It is fine, however, to call C<< ->recv >> when the user of your module
425	requests it (i.e. if you create a http request object ad have a method	923	requests it (i.e. if you create a http request object ad have a method
426	called C<results> that returns the results, it should call C<< ->wait >>	924	called C<results> that returns the results, it should call C<< ->recv >>
427	freely, as the user of your module knows what she is doing. always).	925	freely, as the user of your module knows what she is doing. always).
428		926
429	=head1 WHAT TO DO IN THE MAIN PROGRAM	927	=head1 WHAT TO DO IN THE MAIN PROGRAM
430		928
431	There will always be a single main program - the only place that should	929	There will always be a single main program - the only place that should
…		…
433		931
434	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	932	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
435	do anything special (it does not need to be event-based) and let AnyEvent	933	do anything special (it does not need to be event-based) and let AnyEvent
436	decide which implementation to chose if some module relies on it.	934	decide which implementation to chose if some module relies on it.
437		935
438	If the main program relies on a specific event model. For example, in	936	If the main program relies on a specific event model - for example, in
439	Gtk2 programs you have to rely on the Glib module. You should load the	937	Gtk2 programs you have to rely on the Glib module - you should load the
440	event module before loading AnyEvent or any module that uses it: generally	938	event module before loading AnyEvent or any module that uses it: generally
441	speaking, you should load it as early as possible. The reason is that	939	speaking, you should load it as early as possible. The reason is that
442	modules might create watchers when they are loaded, and AnyEvent will	940	modules might create watchers when they are loaded, and AnyEvent will
443	decide on the event model to use as soon as it creates watchers, and it	941	decide on the event model to use as soon as it creates watchers, and it
444	might chose the wrong one unless you load the correct one yourself.	942	might chose the wrong one unless you load the correct one yourself.
445		943
446	You can chose to use a rather inefficient pure-perl implementation by	944	You can chose to use a pure-perl implementation by loading the
447	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	945	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
448	behaviour everywhere, but letting AnyEvent chose is generally better.	946	everywhere, but letting AnyEvent chose the model is generally better.
		947
		948	=head2 MAINLOOP EMULATION
		949
		950	Sometimes (often for short test scripts, or even standalone programs who
		951	only want to use AnyEvent), you do not want to run a specific event loop.
		952
		953	In that case, you can use a condition variable like this:
		954
		955	AnyEvent->condvar->recv;
		956
		957	This has the effect of entering the event loop and looping forever.
		958
		959	Note that usually your program has some exit condition, in which case
		960	it is better to use the "traditional" approach of storing a condition
		961	variable somewhere, waiting for it, and sending it when the program should
		962	exit cleanly.
		963
		964
		965	=head1 OTHER MODULES
		966
		967	The following is a non-exhaustive list of additional modules that use
		968	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
		969	modules and other event loops in the same program. Some of the modules
		970	come with AnyEvent, most are available via CPAN.
		971
		972	=over 4
		973
		974	=item L<AnyEvent::Util>
		975
		976	Contains various utility functions that replace often-used but blocking
		977	functions such as C<inet_aton> by event-/callback-based versions.
		978
		979	=item L<AnyEvent::Socket>
		980
		981	Provides various utility functions for (internet protocol) sockets,
		982	addresses and name resolution. Also functions to create non-blocking tcp
		983	connections or tcp servers, with IPv6 and SRV record support and more.
		984
		985	=item L<AnyEvent::Handle>
		986
		987	Provide read and write buffers, manages watchers for reads and writes,
		988	supports raw and formatted I/O, I/O queued and fully transparent and
		989	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		990
		991	=item L<AnyEvent::DNS>
		992
		993	Provides rich asynchronous DNS resolver capabilities.
		994
		995	=item L<AnyEvent::HTTP>
		996
		997	A simple-to-use HTTP library that is capable of making a lot of concurrent
		998	HTTP requests.
		999
		1000	=item L<AnyEvent::HTTPD>
		1001
		1002	Provides a simple web application server framework.
		1003
		1004	=item L<AnyEvent::FastPing>
		1005
		1006	The fastest ping in the west.
		1007
		1008	=item L<AnyEvent::DBI>
		1009
		1010	Executes L<DBI> requests asynchronously in a proxy process.
		1011
		1012	=item L<AnyEvent::AIO>
		1013
		1014	Truly asynchronous I/O, should be in the toolbox of every event
		1015	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1016	together.
		1017
		1018	=item L<AnyEvent::BDB>
		1019
		1020	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1021	L<BDB> and AnyEvent together.
		1022
		1023	=item L<AnyEvent::GPSD>
		1024
		1025	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1026
		1027	=item L<AnyEvent::IRC>
		1028
		1029	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1030
		1031	=item L<AnyEvent::XMPP>
		1032
		1033	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1034	Net::XMPP2>.
		1035
		1036	=item L<AnyEvent::IGS>
		1037
		1038	A non-blocking interface to the Internet Go Server protocol (used by
		1039	L<App::IGS>).
		1040
		1041	=item L<Net::FCP>
		1042
		1043	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		1044	of AnyEvent.
		1045
		1046	=item L<Event::ExecFlow>
		1047
		1048	High level API for event-based execution flow control.
		1049
		1050	=item L<Coro>
		1051
		1052	Has special support for AnyEvent via L<Coro::AnyEvent>.
		1053
		1054	=back
449		1055
450	=cut	1056	=cut
451		1057
452	package AnyEvent;	1058	package AnyEvent;
453		1059
		1060	# basically a tuned-down version of common::sense
		1061	sub common_sense {
454	no warnings;	1062	# no warnings
455	use strict;	1063	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1064	# use strict vars subs
		1065	$^H |= 0x00000600;
		1066	}
456		1067
		1068	BEGIN { AnyEvent::common_sense }
		1069
457	use Carp;	1070	use Carp ();
458		1071
459	our $VERSION = '3.3';	1072	our $VERSION = 4.85;
460	our $MODEL;	1073	our $MODEL;
461		1074
462	our $AUTOLOAD;	1075	our $AUTOLOAD;
463	our @ISA;	1076	our @ISA;
464		1077
465	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
466
467	our @REGISTRY;	1078	our @REGISTRY;
468		1079
		1080	our $WIN32;
		1081
		1082	our $VERBOSE;
		1083
		1084	BEGIN {
		1085	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		1086	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1087
		1088	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1089	if ${^TAINT};
		1090
		1091	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1092
		1093	}
		1094
		1095	our $MAX_SIGNAL_LATENCY = 10;
		1096
		1097	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		1098
		1099	{
		1100	my $idx;
		1101	$PROTOCOL{$_} = ++$idx
		1102	for reverse split /\s*,\s*/,
		1103	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		1104	}
		1105
469	my @models = (	1106	my @models = (
470	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
471	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
472	[EV:: => AnyEvent::Impl::EV::],	1107	[EV:: => AnyEvent::Impl::EV::],
473	[Event:: => AnyEvent::Impl::Event::],	1108	[Event:: => AnyEvent::Impl::Event::],
474	[Glib:: => AnyEvent::Impl::Glib::],	1109	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		1110	# everything below here will not be autoprobed
		1111	# as the pureperl backend should work everywhere
		1112	# and is usually faster
		1113	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1114	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
475	[Tk:: => AnyEvent::Impl::Tk::],	1115	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1116	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1117	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
476	[Wx:: => AnyEvent::Impl::POE::],	1118	[Wx:: => AnyEvent::Impl::POE::],
477	[Prima:: => AnyEvent::Impl::POE::],	1119	[Prima:: => AnyEvent::Impl::POE::],
478	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1120	# IO::Async is just too broken - we would need workarounds for its
479	# everything below here will not be autoprobed as the pureperl backend should work everywhere	1121	# byzantine signal and broken child handling, among others.
480	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1122	# IO::Async is rather hard to detect, as it doesn't have any
		1123	# obvious default class.
481	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1124	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
482	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1125	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1126	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
483	);	1127	);
484		1128
485	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	1129	our %method = map +($_ => 1),
		1130	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
		1131
		1132	our @post_detect;
		1133
		1134	sub post_detect(&) {
		1135	my ($cb) = @_;
		1136
		1137	if ($MODEL) {
		1138	$cb->();
		1139
		1140	1
		1141	} else {
		1142	push @post_detect, $cb;
		1143
		1144	defined wantarray
		1145	? bless \$cb, "AnyEvent::Util::postdetect"
		1146	: ()
		1147	}
		1148	}
		1149
		1150	sub AnyEvent::Util::postdetect::DESTROY {
		1151	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1152	}
486		1153
487	sub detect() {	1154	sub detect() {
488	unless ($MODEL) {	1155	unless ($MODEL) {
489	no strict 'refs';	1156	local $SIG{__DIE__};
490		1157
491	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1158	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
492	my $model = "AnyEvent::Impl::$1";	1159	my $model = "AnyEvent::Impl::$1";
493	if (eval "require $model") {	1160	if (eval "require $model") {
494	$MODEL = $model;	1161	$MODEL = $model;
495	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1162	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
496	} else {	1163	} else {
497	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1164	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
498	}	1165	}
499	}	1166	}
500		1167
501	# check for already loaded models	1168	# check for already loaded models
502	unless ($MODEL) {	1169	unless ($MODEL) {
503	for (@REGISTRY, @models) {	1170	for (@REGISTRY, @models) {
504	my ($package, $model) = @$_;	1171	my ($package, $model) = @$_;
505	if (${"$package\::VERSION"} > 0) {	1172	if (${"$package\::VERSION"} > 0) {
506	if (eval "require $model") {	1173	if (eval "require $model") {
507	$MODEL = $model;	1174	$MODEL = $model;
508	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1175	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
509	last;	1176	last;
510	}	1177	}
511	}	1178	}
512	}	1179	}
513		1180
…		…
518	my ($package, $model) = @$_;	1185	my ($package, $model) = @$_;
519	if (eval "require $package"	1186	if (eval "require $package"
520	and ${"$package\::VERSION"} > 0	1187	and ${"$package\::VERSION"} > 0
521	and eval "require $model") {	1188	and eval "require $model") {
522	$MODEL = $model;	1189	$MODEL = $model;
523	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1190	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
524	last;	1191	last;
525	}	1192	}
526	}	1193	}
527		1194
528	$MODEL	1195	$MODEL
529	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	1196	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
530	}	1197	}
531	}	1198	}
532		1199
		1200	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1201
533	unshift @ISA, $MODEL;	1202	unshift @ISA, $MODEL;
534	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1203
		1204	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1205
		1206	(shift @post_detect)->() while @post_detect;
535	}	1207	}
536		1208
537	$MODEL	1209	$MODEL
538	}	1210	}
539		1211
540	sub AUTOLOAD {	1212	sub AUTOLOAD {
541	(my $func = $AUTOLOAD) =~ s/.*://;	1213	(my $func = $AUTOLOAD) =~ s/.*://;
542		1214
543	$method{$func}	1215	$method{$func}
544	or croak "$func: not a valid method for AnyEvent objects";	1216	or Carp::croak "$func: not a valid method for AnyEvent objects";
545		1217
546	detect unless $MODEL;	1218	detect unless $MODEL;
547		1219
548	my $class = shift;	1220	my $class = shift;
549	$class->$func (@_);	1221	$class->$func (@_);
550	}	1222	}
551		1223
		1224	# utility function to dup a filehandle. this is used by many backends
		1225	# to support binding more than one watcher per filehandle (they usually
		1226	# allow only one watcher per fd, so we dup it to get a different one).
		1227	sub _dupfh($$;$$) {
		1228	my ($poll, $fh, $r, $w) = @_;
		1229
		1230	# cygwin requires the fh mode to be matching, unix doesn't
		1231	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1232
		1233	open my $fh2, $mode, $fh
		1234	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1235
		1236	# we assume CLOEXEC is already set by perl in all important cases
		1237
		1238	($fh2, $rw)
		1239	}
		1240
552	package AnyEvent::Base;	1241	package AnyEvent::Base;
553		1242
		1243	# default implementations for many methods
		1244
		1245	sub _time {
		1246	# probe for availability of Time::HiRes
		1247	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1248	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1249	*_time = \&Time::HiRes::time;
		1250	# if (eval "use POSIX (); (POSIX::times())...
		1251	} else {
		1252	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1253	*_time = sub { time }; # epic fail
		1254	}
		1255
		1256	&_time
		1257	}
		1258
		1259	sub time { _time }
		1260	sub now { _time }
		1261	sub now_update { }
		1262
554	# default implementation for ->condvar, ->wait, ->broadcast	1263	# default implementation for ->condvar
555		1264
556	sub condvar {	1265	sub condvar {
557	bless \my $flag, "AnyEvent::Base::CondVar"	1266	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
558	}
559
560	sub AnyEvent::Base::CondVar::broadcast {
561	${$_[0]}++;
562	}
563
564	sub AnyEvent::Base::CondVar::wait {
565	AnyEvent->one_event while !${$_[0]};
566	}	1267	}
567		1268
568	# default implementation for ->signal	1269	# default implementation for ->signal
569		1270
570	our %SIG_CB;	1271	our $HAVE_ASYNC_INTERRUPT;
		1272	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1273	our (%SIG_ASY, %SIG_ASY_W);
		1274	our ($SIG_COUNT, $SIG_TW);
571		1275
		1276	sub _signal_exec {
		1277	$HAVE_ASYNC_INTERRUPT
		1278	? $SIGPIPE_R->drain
		1279	: sysread $SIGPIPE_R, my $dummy, 9;
		1280
		1281	while (%SIG_EV) {
		1282	for (keys %SIG_EV) {
		1283	delete $SIG_EV{$_};
		1284	$_->() for values %{ $SIG_CB{$_} || {} };
		1285	}
		1286	}
		1287	}
		1288
		1289	# install a dumym wakeupw atcher to reduce signal catching latency
		1290	sub _sig_add() {
		1291	unless ($SIG_COUNT++) {
		1292	# try to align timer on a full-second boundary, if possible
		1293	my $NOW = AnyEvent->now;
		1294
		1295	$SIG_TW = AnyEvent->timer (
		1296	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1297	interval => $MAX_SIGNAL_LATENCY,
		1298	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1299	);
		1300	}
		1301	}
		1302
		1303	sub _sig_del {
		1304	undef $SIG_TW
		1305	unless --$SIG_COUNT;
		1306	}
		1307
572	sub signal {	1308	sub _signal {
573	my (undef, %arg) = @_;	1309	my (undef, %arg) = @_;
574		1310
575	my $signal = uc $arg{signal}	1311	my $signal = uc $arg{signal}
576	or Carp::croak "required option 'signal' is missing";	1312	or Carp::croak "required option 'signal' is missing";
577		1313
578	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1314	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1315
		1316	if ($HAVE_ASYNC_INTERRUPT) {
		1317	# async::interrupt
		1318
		1319	$SIG_ASY{$signal} ||= do {
		1320	my $asy = new Async::Interrupt
		1321	cb => sub { undef $SIG_EV{$signal} },
		1322	signal => $signal,
		1323	pipe => [$SIGPIPE_R->filenos],
		1324	;
		1325	$asy->pipe_autodrain (0);
		1326
		1327	$asy
		1328	};
		1329
		1330	} else {
		1331	# pure perl
		1332
579	$SIG{$signal} ||= sub {	1333	$SIG{$signal} ||= sub {
580	$_->() for values %{ $SIG_CB{$signal} || {} };	1334	local $!;
		1335	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1336	undef $SIG_EV{$signal};
		1337	};
		1338
		1339	# can't do signal processing without introducing races in pure perl,
		1340	# so limit the signal latency.
		1341	_sig_add;
581	};	1342	}
582		1343
583	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1344	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
584	}	1345	}
585		1346
		1347	sub signal {
		1348	# probe for availability of Async::Interrupt
		1349	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1350	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1351
		1352	$HAVE_ASYNC_INTERRUPT = 1;
		1353	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1354	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1355
		1356	} else {
		1357	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1358
		1359	require Fcntl;
		1360
		1361	if (AnyEvent::WIN32) {
		1362	require AnyEvent::Util;
		1363
		1364	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1365	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1366	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1367	} else {
		1368	pipe $SIGPIPE_R, $SIGPIPE_W;
		1369	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1370	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1371
		1372	# not strictly required, as $^F is normally 2, but let's make sure...
		1373	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1374	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1375	}
		1376
		1377	$SIGPIPE_R
		1378	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1379
		1380	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1381	}
		1382
		1383	*signal = \&_signal;
		1384	&signal
		1385	}
		1386
586	sub AnyEvent::Base::Signal::DESTROY {	1387	sub AnyEvent::Base::signal::DESTROY {
587	my ($signal, $cb) = @{$_[0]};	1388	my ($signal, $cb) = @{$_[0]};
588		1389
		1390	_sig_del;
		1391
589	delete $SIG_CB{$signal}{$cb};	1392	delete $SIG_CB{$signal}{$cb};
590		1393
591	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1394	$HAVE_ASYNC_INTERRUPT
		1395	? delete $SIG_ASY{$signal}
		1396	: # delete doesn't work with older perls - they then
		1397	# print weird messages, or just unconditionally exit
		1398	# instead of getting the default action.
		1399	undef $SIG{$signal}
		1400	unless keys %{ $SIG_CB{$signal} };
592	}	1401	}
593		1402
594	# default implementation for ->child	1403	# default implementation for ->child
595		1404
596	our %PID_CB;	1405	our %PID_CB;
597	our $CHLD_W;	1406	our $CHLD_W;
598	our $CHLD_DELAY_W;	1407	our $CHLD_DELAY_W;
599	our $PID_IDLE;
600	our $WNOHANG;	1408	our $WNOHANG;
601		1409
602	sub _child_wait {	1410	sub _sigchld {
603	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1411	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1412	$_->($pid, $?)
604	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1413	for values %{ $PID_CB{$pid} || {} },
605	(values %{ $PID_CB{0} || {} });	1414	values %{ $PID_CB{0} || {} };
606	}	1415	}
607
608	undef $PID_IDLE;
609	}
610
611	sub _sigchld {
612	# make sure we deliver these changes "synchronous" with the event loop.
613	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
614	undef $CHLD_DELAY_W;
615	&_child_wait;
616	});
617	}	1416	}
618		1417
619	sub child {	1418	sub child {
620	my (undef, %arg) = @_;	1419	my (undef, %arg) = @_;
621		1420
622	defined (my $pid = $arg{pid} + 0)	1421	defined (my $pid = $arg{pid} + 0)
623	or Carp::croak "required option 'pid' is missing";	1422	or Carp::croak "required option 'pid' is missing";
624		1423
625	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1424	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
626		1425
627	unless ($WNOHANG) {	1426	# WNOHANG is almost cetrainly 1 everywhere
628	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1427	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
629	}	1428	? 1
		1429	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
630		1430
631	unless ($CHLD_W) {	1431	unless ($CHLD_W) {
632	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1432	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
633	# child could be a zombie already, so make at least one round	1433	# child could be a zombie already, so make at least one round
634	&_sigchld;	1434	&_sigchld;
635	}	1435	}
636		1436
637	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1437	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
638	}	1438	}
639		1439
640	sub AnyEvent::Base::Child::DESTROY {	1440	sub AnyEvent::Base::child::DESTROY {
641	my ($pid, $cb) = @{$_[0]};	1441	my ($pid, $cb) = @{$_[0]};
642		1442
643	delete $PID_CB{$pid}{$cb};	1443	delete $PID_CB{$pid}{$cb};
644	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1444	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
645		1445
646	undef $CHLD_W unless keys %PID_CB;	1446	undef $CHLD_W unless keys %PID_CB;
647	}	1447	}
		1448
		1449	# idle emulation is done by simply using a timer, regardless
		1450	# of whether the process is idle or not, and not letting
		1451	# the callback use more than 50% of the time.
		1452	sub idle {
		1453	my (undef, %arg) = @_;
		1454
		1455	my ($cb, $w, $rcb) = $arg{cb};
		1456
		1457	$rcb = sub {
		1458	if ($cb) {
		1459	$w = _time;
		1460	&$cb;
		1461	$w = _time - $w;
		1462
		1463	# never use more then 50% of the time for the idle watcher,
		1464	# within some limits
		1465	$w = 0.0001 if $w < 0.0001;
		1466	$w = 5 if $w > 5;
		1467
		1468	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1469	} else {
		1470	# clean up...
		1471	undef $w;
		1472	undef $rcb;
		1473	}
		1474	};
		1475
		1476	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1477
		1478	bless \\$cb, "AnyEvent::Base::idle"
		1479	}
		1480
		1481	sub AnyEvent::Base::idle::DESTROY {
		1482	undef $${$_[0]};
		1483	}
		1484
		1485	package AnyEvent::CondVar;
		1486
		1487	our @ISA = AnyEvent::CondVar::Base::;
		1488
		1489	package AnyEvent::CondVar::Base;
		1490
		1491	#use overload
		1492	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1493	# fallback => 1;
		1494
		1495	# save 300+ kilobytes by dirtily hardcoding overloading
		1496	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1497	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1498	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1499	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1500
		1501	our $WAITING;
		1502
		1503	sub _send {
		1504	# nop
		1505	}
		1506
		1507	sub send {
		1508	my $cv = shift;
		1509	$cv->{_ae_sent} = [@_];
		1510	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1511	$cv->_send;
		1512	}
		1513
		1514	sub croak {
		1515	$_[0]{_ae_croak} = $_[1];
		1516	$_[0]->send;
		1517	}
		1518
		1519	sub ready {
		1520	$_[0]{_ae_sent}
		1521	}
		1522
		1523	sub _wait {
		1524	$WAITING
		1525	and !$_[0]{_ae_sent}
		1526	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1527
		1528	local $WAITING = 1;
		1529	AnyEvent->one_event while !$_[0]{_ae_sent};
		1530	}
		1531
		1532	sub recv {
		1533	$_[0]->_wait;
		1534
		1535	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1536	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1537	}
		1538
		1539	sub cb {
		1540	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1541	$_[0]{_ae_cb}
		1542	}
		1543
		1544	sub begin {
		1545	++$_[0]{_ae_counter};
		1546	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1547	}
		1548
		1549	sub end {
		1550	return if --$_[0]{_ae_counter};
		1551	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1552	}
		1553
		1554	# undocumented/compatibility with pre-3.4
		1555	*broadcast = \&send;
		1556	*wait = \&_wait;
		1557
		1558	=head1 ERROR AND EXCEPTION HANDLING
		1559
		1560	In general, AnyEvent does not do any error handling - it relies on the
		1561	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1562	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1563	checking of all AnyEvent methods, however, which is highly useful during
		1564	development.
		1565
		1566	As for exception handling (i.e. runtime errors and exceptions thrown while
		1567	executing a callback), this is not only highly event-loop specific, but
		1568	also not in any way wrapped by this module, as this is the job of the main
		1569	program.
		1570
		1571	The pure perl event loop simply re-throws the exception (usually
		1572	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1573	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1574	so on.
		1575
		1576	=head1 ENVIRONMENT VARIABLES
		1577
		1578	The following environment variables are used by this module or its
		1579	submodules.
		1580
		1581	Note that AnyEvent will remove I<all> environment variables starting with
		1582	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1583	enabled.
		1584
		1585	=over 4
		1586
		1587	=item C<PERL_ANYEVENT_VERBOSE>
		1588
		1589	By default, AnyEvent will be completely silent except in fatal
		1590	conditions. You can set this environment variable to make AnyEvent more
		1591	talkative.
		1592
		1593	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1594	conditions, such as not being able to load the event model specified by
		1595	C<PERL_ANYEVENT_MODEL>.
		1596
		1597	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1598	model it chooses.
		1599
		1600	When set to C<8> or higher, then AnyEvent will report extra information on
		1601	which optional modules it loads and how it implements certain features.
		1602
		1603	=item C<PERL_ANYEVENT_STRICT>
		1604
		1605	AnyEvent does not do much argument checking by default, as thorough
		1606	argument checking is very costly. Setting this variable to a true value
		1607	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1608	check the arguments passed to most method calls. If it finds any problems,
		1609	it will croak.
		1610
		1611	In other words, enables "strict" mode.
		1612
		1613	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1614	>>, it is definitely recommended to keep it off in production. Keeping
		1615	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1616	can be very useful, however.
		1617
		1618	=item C<PERL_ANYEVENT_MODEL>
		1619
		1620	This can be used to specify the event model to be used by AnyEvent, before
		1621	auto detection and -probing kicks in. It must be a string consisting
		1622	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1623	and the resulting module name is loaded and if the load was successful,
		1624	used as event model. If it fails to load AnyEvent will proceed with
		1625	auto detection and -probing.
		1626
		1627	This functionality might change in future versions.
		1628
		1629	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1630	could start your program like this:
		1631
		1632	PERL_ANYEVENT_MODEL=Perl perl ...
		1633
		1634	=item C<PERL_ANYEVENT_PROTOCOLS>
		1635
		1636	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1637	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1638	of auto probing).
		1639
		1640	Must be set to a comma-separated list of protocols or address families,
		1641	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1642	used, and preference will be given to protocols mentioned earlier in the
		1643	list.
		1644
		1645	This variable can effectively be used for denial-of-service attacks
		1646	against local programs (e.g. when setuid), although the impact is likely
		1647	small, as the program has to handle conenction and other failures anyways.
		1648
		1649	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1650	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1651	- only support IPv4, never try to resolve or contact IPv6
		1652	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1653	IPv6, but prefer IPv6 over IPv4.
		1654
		1655	=item C<PERL_ANYEVENT_EDNS0>
		1656
		1657	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1658	for DNS. This extension is generally useful to reduce DNS traffic, but
		1659	some (broken) firewalls drop such DNS packets, which is why it is off by
		1660	default.
		1661
		1662	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1663	EDNS0 in its DNS requests.
		1664
		1665	=item C<PERL_ANYEVENT_MAX_FORKS>
		1666
		1667	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1668	will create in parallel.
		1669
		1670	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1671
		1672	The default value for the C<max_outstanding> parameter for the default DNS
		1673	resolver - this is the maximum number of parallel DNS requests that are
		1674	sent to the DNS server.
		1675
		1676	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1677
		1678	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1679	configuration) in the default resolver. When set to the empty string, no
		1680	default config will be used.
		1681
		1682	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1683
		1684	When neither C<ca_file> nor C<ca_path> was specified during
		1685	L<AnyEvent::TLS> context creation, and either of these environment
		1686	variables exist, they will be used to specify CA certificate locations
		1687	instead of a system-dependent default.
		1688
		1689	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1690
		1691	When these are set to C<1>, then the respective modules are not
		1692	loaded. Mostly good for testing AnyEvent itself.
		1693
		1694	=back
648		1695
649	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1696	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
650		1697
651	This is an advanced topic that you do not normally need to use AnyEvent in	1698	This is an advanced topic that you do not normally need to use AnyEvent in
652	a module. This section is only of use to event loop authors who want to	1699	a module. This section is only of use to event loop authors who want to
…		…
686		1733
687	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1734	I<rxvt-unicode> also cheats a bit by not providing blocking access to
688	condition variables: code blocking while waiting for a condition will	1735	condition variables: code blocking while waiting for a condition will
689	C<die>. This still works with most modules/usages, and blocking calls must	1736	C<die>. This still works with most modules/usages, and blocking calls must
690	not be done in an interactive application, so it makes sense.	1737	not be done in an interactive application, so it makes sense.
691
692	=head1 ENVIRONMENT VARIABLES
693
694	The following environment variables are used by this module:
695
696	=over 4
697
698	=item C<PERL_ANYEVENT_VERBOSE>
699
700	By default, AnyEvent will be completely silent except in fatal
701	conditions. You can set this environment variable to make AnyEvent more
702	talkative.
703
704	When set to C<1> or higher, causes AnyEvent to warn about unexpected
705	conditions, such as not being able to load the event model specified by
706	C<PERL_ANYEVENT_MODEL>.
707
708	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
709	model it chooses.
710
711	=item C<PERL_ANYEVENT_MODEL>
712
713	This can be used to specify the event model to be used by AnyEvent, before
714	autodetection and -probing kicks in. It must be a string consisting
715	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
716	and the resulting module name is loaded and if the load was successful,
717	used as event model. If it fails to load AnyEvent will proceed with
718	autodetection and -probing.
719
720	This functionality might change in future versions.
721
722	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
723	could start your program like this:
724
725	PERL_ANYEVENT_MODEL=Perl perl ...
726
727	=back
728		1738
729	=head1 EXAMPLE PROGRAM	1739	=head1 EXAMPLE PROGRAM
730		1740
731	The following program uses an I/O watcher to read data from STDIN, a timer	1741	The following program uses an I/O watcher to read data from STDIN, a timer
732	to display a message once per second, and a condition variable to quit the	1742	to display a message once per second, and a condition variable to quit the
…		…
741	poll => 'r',	1751	poll => 'r',
742	cb => sub {	1752	cb => sub {
743	warn "io event <$_[0]>\n"; # will always output <r>	1753	warn "io event <$_[0]>\n"; # will always output <r>
744	chomp (my $input = <STDIN>); # read a line	1754	chomp (my $input = <STDIN>); # read a line
745	warn "read: $input\n"; # output what has been read	1755	warn "read: $input\n"; # output what has been read
746	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1756	$cv->send if $input =~ /^q/i; # quit program if /^q/i
747	},	1757	},
748	);	1758	);
749		1759
750	my $time_watcher; # can only be used once	1760	my $time_watcher; # can only be used once
751		1761
…		…
756	});	1766	});
757	}	1767	}
758		1768
759	new_timer; # create first timer	1769	new_timer; # create first timer
760		1770
761	$cv->wait; # wait until user enters /^q/i	1771	$cv->recv; # wait until user enters /^q/i
762		1772
763	=head1 REAL-WORLD EXAMPLE	1773	=head1 REAL-WORLD EXAMPLE
764		1774
765	Consider the L<Net::FCP> module. It features (among others) the following	1775	Consider the L<Net::FCP> module. It features (among others) the following
766	API calls, which are to freenet what HTTP GET requests are to http:	1776	API calls, which are to freenet what HTTP GET requests are to http:
…		…
816	syswrite $txn->{fh}, $txn->{request}	1826	syswrite $txn->{fh}, $txn->{request}
817	or die "connection or write error";	1827	or die "connection or write error";
818	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1828	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
819		1829
820	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1830	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
821	result and signals any possible waiters that the request ahs finished:	1831	result and signals any possible waiters that the request has finished:
822		1832
823	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1833	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
824		1834
825	if (end-of-file or data complete) {	1835	if (end-of-file or data complete) {
826	$txn->{result} = $txn->{buf};	1836	$txn->{result} = $txn->{buf};
827	$txn->{finished}->broadcast;	1837	$txn->{finished}->send;
828	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1838	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
829	}	1839	}
830		1840
831	The C<result> method, finally, just waits for the finished signal (if the	1841	The C<result> method, finally, just waits for the finished signal (if the
832	request was already finished, it doesn't wait, of course, and returns the	1842	request was already finished, it doesn't wait, of course, and returns the
833	data:	1843	data:
834		1844
835	$txn->{finished}->wait;	1845	$txn->{finished}->recv;
836	return $txn->{result};	1846	return $txn->{result};
837		1847
838	The actual code goes further and collects all errors (C<die>s, exceptions)	1848	The actual code goes further and collects all errors (C<die>s, exceptions)
839	that occured during request processing. The C<result> method detects	1849	that occurred during request processing. The C<result> method detects
840	whether an exception as thrown (it is stored inside the $txn object)	1850	whether an exception as thrown (it is stored inside the $txn object)
841	and just throws the exception, which means connection errors and other	1851	and just throws the exception, which means connection errors and other
842	problems get reported tot he code that tries to use the result, not in a	1852	problems get reported tot he code that tries to use the result, not in a
843	random callback.	1853	random callback.
844		1854
…		…
875		1885
876	my $quit = AnyEvent->condvar;	1886	my $quit = AnyEvent->condvar;
877		1887
878	$fcp->txn_client_get ($url)->cb (sub {	1888	$fcp->txn_client_get ($url)->cb (sub {
879	...	1889	...
880	$quit->broadcast;	1890	$quit->send;
881	});	1891	});
882		1892
883	$quit->wait;	1893	$quit->recv;
884		1894
885		1895
886	=head1 BENCHMARK	1896	=head1 BENCHMARKS
887		1897
888	To give you an idea of the performance and overheads that AnyEvent adds	1898	To give you an idea of the performance and overheads that AnyEvent adds
889	over the event loops themselves (and to give you an impression of the	1899	over the event loops themselves and to give you an impression of the speed
890	speed of various event loops), here is a benchmark of various supported	1900	of various event loops I prepared some benchmarks.
891	event models natively and with anyevent. The benchmark creates a lot of	1901
892	timers (with a zero timeout) and I/O watchers (watching STDOUT, a pty, to	1902	=head2 BENCHMARKING ANYEVENT OVERHEAD
		1903
		1904	Here is a benchmark of various supported event models used natively and
		1905	through AnyEvent. The benchmark creates a lot of timers (with a zero
		1906	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
893	become writable, which it is), lets them fire exactly once and destroys	1907	which it is), lets them fire exactly once and destroys them again.
894	them again.
895		1908
896	Rewriting the benchmark to use many different sockets instead of using	1909	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
897	the same filehandle for all I/O watchers results in a much longer runtime	1910	distribution.
898	(socket creation is expensive), but qualitatively the same figures, so it
899	was not used.
900		1911
901	=head2 Explanation of the columns	1912	=head3 Explanation of the columns
902		1913
903	I<watcher> is the number of event watchers created/destroyed. Since	1914	I<watcher> is the number of event watchers created/destroyed. Since
904	different event models feature vastly different performances, each event	1915	different event models feature vastly different performances, each event
905	loop was given a number of watchers so that overall runtime is acceptable	1916	loop was given a number of watchers so that overall runtime is acceptable
906	and similar between tested event loop (and keep them from crashing): Glib	1917	and similar between tested event loop (and keep them from crashing): Glib
…		…
916	all watchers, to avoid adding memory overhead. That means closure creation	1927	all watchers, to avoid adding memory overhead. That means closure creation
917	and memory usage is not included in the figures.	1928	and memory usage is not included in the figures.
918		1929
919	I<invoke> is the time, in microseconds, used to invoke a simple	1930	I<invoke> is the time, in microseconds, used to invoke a simple
920	callback. The callback simply counts down a Perl variable and after it was	1931	callback. The callback simply counts down a Perl variable and after it was
921	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1932	invoked "watcher" times, it would C<< ->send >> a condvar once to
922	signal the end of this phase.	1933	signal the end of this phase.
923		1934
924	I<destroy> is the time, in microseconds, that it takes to destroy a single	1935	I<destroy> is the time, in microseconds, that it takes to destroy a single
925	watcher.	1936	watcher.
926		1937
927	=head2 Results	1938	=head3 Results
928		1939
929	name watchers bytes create invoke destroy comment	1940	name watchers bytes create invoke destroy comment
930	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1941	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
931	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1942	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
932	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1943	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
933	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1944	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
934	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1945	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
935	Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers	1946	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1947	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1948	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
936	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1949	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
937	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1950	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
938	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1951	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
939	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1952	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
940		1953
941	=head2 Discussion	1954	=head3 Discussion
942		1955
943	The benchmark does I<not> measure scalability of the event loop very	1956	The benchmark does I<not> measure scalability of the event loop very
944	well. For example, a select-based event loop (such as the pure perl one)	1957	well. For example, a select-based event loop (such as the pure perl one)
945	can never compete with an event loop that uses epoll when the number of	1958	can never compete with an event loop that uses epoll when the number of
946	file descriptors grows high. In this benchmark, all events become ready at	1959	file descriptors grows high. In this benchmark, all events become ready at
947	the same time, so select/poll-based implementations get an unnatural speed	1960	the same time, so select/poll-based implementations get an unnatural speed
948	boost.	1961	boost.
949		1962
		1963	Also, note that the number of watchers usually has a nonlinear effect on
		1964	overall speed, that is, creating twice as many watchers doesn't take twice
		1965	the time - usually it takes longer. This puts event loops tested with a
		1966	higher number of watchers at a disadvantage.
		1967
		1968	To put the range of results into perspective, consider that on the
		1969	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1970	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1971	cycles with POE.
		1972
950	C<EV> is the sole leader regarding speed and memory use, which are both	1973	C<EV> is the sole leader regarding speed and memory use, which are both
951	maximal/minimal, respectively. Even when going through AnyEvent, there are	1974	maximal/minimal, respectively. Even when going through AnyEvent, it uses
952	only two event loops that use slightly less memory (the C<Event> module	1975	far less memory than any other event loop and is still faster than Event
953	natively and the pure perl backend), and no faster event models, not even	1976	natively.
954	C<Event> natively.
955		1977
956	The pure perl implementation is hit in a few sweet spots (both the	1978	The pure perl implementation is hit in a few sweet spots (both the
957	zero timeout and the use of a single fd hit optimisations in the perl	1979	constant timeout and the use of a single fd hit optimisations in the perl
958	interpreter and the backend itself, and all watchers become ready at the	1980	interpreter and the backend itself). Nevertheless this shows that it
959	same time). Nevertheless this shows that it adds very little overhead in	1981	adds very little overhead in itself. Like any select-based backend its
960	itself. Like any select-based backend its performance becomes really bad	1982	performance becomes really bad with lots of file descriptors (and few of
961	with lots of file descriptors (and few of them active), of course, but	1983	them active), of course, but this was not subject of this benchmark.
962	this was not subject of this benchmark.
963		1984
964	The C<Event> module has a relatively high setup and callback invocation cost,	1985	The C<Event> module has a relatively high setup and callback invocation
965	but overall scores on the third place.	1986	cost, but overall scores in on the third place.
966		1987
		1988	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1989	when using its pure perl backend.
		1990
967	C<Glib>'s memory usage is quite a bit bit higher, but it features a	1991	C<Glib>'s memory usage is quite a bit higher, but it features a
968	faster callback invocation and overall ends up in the same class as	1992	faster callback invocation and overall ends up in the same class as
969	C<Event>. However, Glib scales extremely badly, doubling the number of	1993	C<Event>. However, Glib scales extremely badly, doubling the number of
970	watchers increases the processing time by more than a factor of four,	1994	watchers increases the processing time by more than a factor of four,
971	making it completely unusable when using larger numbers of watchers	1995	making it completely unusable when using larger numbers of watchers
972	(note that only a single file descriptor was used in the benchmark, so	1996	(note that only a single file descriptor was used in the benchmark, so
…		…
975	The C<Tk> adaptor works relatively well. The fact that it crashes with	1999	The C<Tk> adaptor works relatively well. The fact that it crashes with
976	more than 2000 watchers is a big setback, however, as correctness takes	2000	more than 2000 watchers is a big setback, however, as correctness takes
977	precedence over speed. Nevertheless, its performance is surprising, as the	2001	precedence over speed. Nevertheless, its performance is surprising, as the
978	file descriptor is dup()ed for each watcher. This shows that the dup()	2002	file descriptor is dup()ed for each watcher. This shows that the dup()
979	employed by some adaptors is not a big performance issue (it does incur a	2003	employed by some adaptors is not a big performance issue (it does incur a
980	hidden memory cost inside the kernel, though, that is not reflected in the	2004	hidden memory cost inside the kernel which is not reflected in the figures
981	figures above).	2005	above).
982		2006
983	C<POE>, regardless of underlying event loop (wether using its pure perl	2007	C<POE>, regardless of underlying event loop (whether using its pure perl
984	select-based backend or the Event module) shows abysmal performance and	2008	select-based backend or the Event module, the POE-EV backend couldn't
		2009	be tested because it wasn't working) shows abysmal performance and
985	memory usage: Watchers use almost 30 times as much memory as EV watchers,	2010	memory usage with AnyEvent: Watchers use almost 30 times as much memory
986	and 10 times as much memory as both Event or EV via AnyEvent. Watcher	2011	as EV watchers, and 10 times as much memory as Event (the high memory
		2012	requirements are caused by requiring a session for each watcher). Watcher
987	invocation is almost 900 times slower than with AnyEvent's pure perl	2013	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		2014	implementation.
		2015
988	implementation. The design of the POE adaptor class in AnyEvent can not	2016	The design of the POE adaptor class in AnyEvent can not really account
989	really account for this, as session creation overhead is small compared	2017	for the performance issues, though, as session creation overhead is
990	to execution of the state machine, which is coded pretty optimally within	2018	small compared to execution of the state machine, which is coded pretty
991	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	2019	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		2020	using multiple sessions is not a good approach, especially regarding
		2021	memory usage, even the author of POE could not come up with a faster
		2022	design).
992		2023
993	=head2 Summary	2024	=head3 Summary
994		2025
		2026	=over 4
		2027
995	Using EV through AnyEvent is faster than any other event loop, but most	2028	=item * Using EV through AnyEvent is faster than any other event loop
996	event loops have acceptable performance with or without AnyEvent.	2029	(even when used without AnyEvent), but most event loops have acceptable
		2030	performance with or without AnyEvent.
997		2031
998	The overhead AnyEvent adds is usually much smaller than the overhead of	2032	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
999	the actual event loop, only with extremely fast event loops such as the EV	2033	the actual event loop, only with extremely fast event loops such as EV
1000	adds AnyEvent significant overhead.	2034	adds AnyEvent significant overhead.
1001		2035
1002	And you should simply avoid POE like the plague if you want performance or	2036	=item * You should avoid POE like the plague if you want performance or
1003	reasonable memory usage.	2037	reasonable memory usage.
1004		2038
		2039	=back
		2040
		2041	=head2 BENCHMARKING THE LARGE SERVER CASE
		2042
		2043	This benchmark actually benchmarks the event loop itself. It works by
		2044	creating a number of "servers": each server consists of a socket pair, a
		2045	timeout watcher that gets reset on activity (but never fires), and an I/O
		2046	watcher waiting for input on one side of the socket. Each time the socket
		2047	watcher reads a byte it will write that byte to a random other "server".
		2048
		2049	The effect is that there will be a lot of I/O watchers, only part of which
		2050	are active at any one point (so there is a constant number of active
		2051	fds for each loop iteration, but which fds these are is random). The
		2052	timeout is reset each time something is read because that reflects how
		2053	most timeouts work (and puts extra pressure on the event loops).
		2054
		2055	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
		2056	(1%) are active. This mirrors the activity of large servers with many
		2057	connections, most of which are idle at any one point in time.
		2058
		2059	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
		2060	distribution.
		2061
		2062	=head3 Explanation of the columns
		2063
		2064	I<sockets> is the number of sockets, and twice the number of "servers" (as
		2065	each server has a read and write socket end).
		2066
		2067	I<create> is the time it takes to create a socket pair (which is
		2068	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
		2069
		2070	I<request>, the most important value, is the time it takes to handle a
		2071	single "request", that is, reading the token from the pipe and forwarding
		2072	it to another server. This includes deleting the old timeout and creating
		2073	a new one that moves the timeout into the future.
		2074
		2075	=head3 Results
		2076
		2077	name sockets create request
		2078	EV 20000 69.01 11.16
		2079	Perl 20000 73.32 35.87
		2080	IOAsync 20000 157.00 98.14 epoll
		2081	IOAsync 20000 159.31 616.06 poll
		2082	Event 20000 212.62 257.32
		2083	Glib 20000 651.16 1896.30
		2084	POE 20000 349.67 12317.24 uses POE::Loop::Event
		2085
		2086	=head3 Discussion
		2087
		2088	This benchmark I<does> measure scalability and overall performance of the
		2089	particular event loop.
		2090
		2091	EV is again fastest. Since it is using epoll on my system, the setup time
		2092	is relatively high, though.
		2093
		2094	Perl surprisingly comes second. It is much faster than the C-based event
		2095	loops Event and Glib.
		2096
		2097	IO::Async performs very well when using its epoll backend, and still quite
		2098	good compared to Glib when using its pure perl backend.
		2099
		2100	Event suffers from high setup time as well (look at its code and you will
		2101	understand why). Callback invocation also has a high overhead compared to
		2102	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
		2103	uses select or poll in basically all documented configurations.
		2104
		2105	Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It
		2106	clearly fails to perform with many filehandles or in busy servers.
		2107
		2108	POE is still completely out of the picture, taking over 1000 times as long
		2109	as EV, and over 100 times as long as the Perl implementation, even though
		2110	it uses a C-based event loop in this case.
		2111
		2112	=head3 Summary
		2113
		2114	=over 4
		2115
		2116	=item * The pure perl implementation performs extremely well.
		2117
		2118	=item * Avoid Glib or POE in large projects where performance matters.
		2119
		2120	=back
		2121
		2122	=head2 BENCHMARKING SMALL SERVERS
		2123
		2124	While event loops should scale (and select-based ones do not...) even to
		2125	large servers, most programs we (or I :) actually write have only a few
		2126	I/O watchers.
		2127
		2128	In this benchmark, I use the same benchmark program as in the large server
		2129	case, but it uses only eight "servers", of which three are active at any
		2130	one time. This should reflect performance for a small server relatively
		2131	well.
		2132
		2133	The columns are identical to the previous table.
		2134
		2135	=head3 Results
		2136
		2137	name sockets create request
		2138	EV 16 20.00 6.54
		2139	Perl 16 25.75 12.62
		2140	Event 16 81.27 35.86
		2141	Glib 16 32.63 15.48
		2142	POE 16 261.87 276.28 uses POE::Loop::Event
		2143
		2144	=head3 Discussion
		2145
		2146	The benchmark tries to test the performance of a typical small
		2147	server. While knowing how various event loops perform is interesting, keep
		2148	in mind that their overhead in this case is usually not as important, due
		2149	to the small absolute number of watchers (that is, you need efficiency and
		2150	speed most when you have lots of watchers, not when you only have a few of
		2151	them).
		2152
		2153	EV is again fastest.
		2154
		2155	Perl again comes second. It is noticeably faster than the C-based event
		2156	loops Event and Glib, although the difference is too small to really
		2157	matter.
		2158
		2159	POE also performs much better in this case, but is is still far behind the
		2160	others.
		2161
		2162	=head3 Summary
		2163
		2164	=over 4
		2165
		2166	=item * C-based event loops perform very well with small number of
		2167	watchers, as the management overhead dominates.
		2168
		2169	=back
		2170
		2171	=head2 THE IO::Lambda BENCHMARK
		2172
		2173	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2174	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2175	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2176	shouldn't come as a surprise to anybody). As such, the benchmark is
		2177	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2178	very optimal. But how would AnyEvent compare when used without the extra
		2179	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2180
		2181	The benchmark itself creates an echo-server, and then, for 500 times,
		2182	connects to the echo server, sends a line, waits for the reply, and then
		2183	creates the next connection. This is a rather bad benchmark, as it doesn't
		2184	test the efficiency of the framework or much non-blocking I/O, but it is a
		2185	benchmark nevertheless.
		2186
		2187	name runtime
		2188	Lambda/select 0.330 sec
		2189	+ optimized 0.122 sec
		2190	Lambda/AnyEvent 0.327 sec
		2191	+ optimized 0.138 sec
		2192	Raw sockets/select 0.077 sec
		2193	POE/select, components 0.662 sec
		2194	POE/select, raw sockets 0.226 sec
		2195	POE/select, optimized 0.404 sec
		2196
		2197	AnyEvent/select/nb 0.085 sec
		2198	AnyEvent/EV/nb 0.068 sec
		2199	+state machine 0.134 sec
		2200
		2201	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2202	benchmarks actually make blocking connects and use 100% blocking I/O,
		2203	defeating the purpose of an event-based solution. All of the newly
		2204	written AnyEvent benchmarks use 100% non-blocking connects (using
		2205	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2206	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2207	generally require a lot more bookkeeping and event handling than blocking
		2208	connects (which involve a single syscall only).
		2209
		2210	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2211	offers similar expressive power as POE and IO::Lambda, using conventional
		2212	Perl syntax. This means that both the echo server and the client are 100%
		2213	non-blocking, further placing it at a disadvantage.
		2214
		2215	As you can see, the AnyEvent + EV combination even beats the
		2216	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2217	backend easily beats IO::Lambda and POE.
		2218
		2219	And even the 100% non-blocking version written using the high-level (and
		2220	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2221	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2222	in a non-blocking way.
		2223
		2224	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2225	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2226	part of the IO::lambda distribution and were used without any changes.
		2227
		2228
		2229	=head1 SIGNALS
		2230
		2231	AnyEvent currently installs handlers for these signals:
		2232
		2233	=over 4
		2234
		2235	=item SIGCHLD
		2236
		2237	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2238	emulation for event loops that do not support them natively. Also, some
		2239	event loops install a similar handler.
		2240
		2241	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2242	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2243
		2244	=item SIGPIPE
		2245
		2246	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2247	when AnyEvent gets loaded.
		2248
		2249	The rationale for this is that AnyEvent users usually do not really depend
		2250	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2251	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2252	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2253	some random socket.
		2254
		2255	The rationale for installing a no-op handler as opposed to ignoring it is
		2256	that this way, the handler will be restored to defaults on exec.
		2257
		2258	Feel free to install your own handler, or reset it to defaults.
		2259
		2260	=back
		2261
		2262	=cut
		2263
		2264	undef $SIG{CHLD}
		2265	if $SIG{CHLD} eq 'IGNORE';
		2266
		2267	$SIG{PIPE} = sub { }
		2268	unless defined $SIG{PIPE};
		2269
		2270	=head1 RECOMMENDED/OPTIONAL MODULES
		2271
		2272	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2273	it's built-in modules) are required to use it.
		2274
		2275	That does not mean that AnyEvent won't take advantage of some additional
		2276	modules if they are installed.
		2277
		2278	This section epxlains which additional modules will be used, and how they
		2279	affect AnyEvent's operetion.
		2280
		2281	=over 4
		2282
		2283	=item L<Async::Interrupt>
		2284
		2285	This slightly arcane module is used to implement fast signal handling: To
		2286	my knowledge, there is no way to do completely race-free and quick
		2287	signal handling in pure perl. To ensure that signals still get
		2288	delivered, AnyEvent will start an interval timer to wake up perl (and
		2289	catch the signals) with some delay (default is 10 seconds, look for
		2290	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2291
		2292	If this module is available, then it will be used to implement signal
		2293	catching, which means that signals will not be delayed, and the event loop
		2294	will not be interrupted regularly, which is more efficient (And good for
		2295	battery life on laptops).
		2296
		2297	This affects not just the pure-perl event loop, but also other event loops
		2298	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2299
		2300	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2301	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2302	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2303	does nothing for those backends.
		2304
		2305	=item L<EV>
		2306
		2307	This module isn't really "optional", as it is simply one of the backend
		2308	event loops that AnyEvent can use. However, it is simply the best event
		2309	loop available in terms of features, speed and stability: It supports
		2310	the AnyEvent API optimally, implements all the watcher types in XS, does
		2311	automatic timer adjustments even when no monotonic clock is available,
		2312	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2313	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2314	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2315
		2316	=item L<Guard>
		2317
		2318	The guard module, when used, will be used to implement
		2319	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2320	lot less memory), but otherwise doesn't affect guard operation much. It is
		2321	purely used for performance.
		2322
		2323	=item L<JSON> and L<JSON::XS>
		2324
		2325	This module is required when you want to read or write JSON data via
		2326	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2327	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2328
		2329	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2330	installed.
		2331
		2332	=item L<Net::SSLeay>
		2333
		2334	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2335	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2336	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2337
		2338	=item L<Time::HiRes>
		2339
		2340	This module is part of perl since release 5.008. It will be used when the
		2341	chosen event library does not come with a timing source on it's own. The
		2342	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2343	try to use a monotonic clock for timing stability.
		2344
		2345	=back
		2346
1005		2347
1006	=head1 FORK	2348	=head1 FORK
1007		2349
1008	Most event libraries are not fork-safe. The ones who are usually are	2350	Most event libraries are not fork-safe. The ones who are usually are
1009	because they are so inefficient. Only L<EV> is fully fork-aware.	2351	because they rely on inefficient but fork-safe C<select> or C<poll>
		2352	calls. Only L<EV> is fully fork-aware.
1010		2353
1011	If you have to fork, you must either do so I<before> creating your first	2354	If you have to fork, you must either do so I<before> creating your first
1012	watcher OR you must not use AnyEvent at all in the child.	2355	watcher OR you must not use AnyEvent at all in the child OR you must do
		2356	something completely out of the scope of AnyEvent.
1013		2357
1014		2358
1015	=head1 SECURITY CONSIDERATIONS	2359	=head1 SECURITY CONSIDERATIONS
1016		2360
1017	AnyEvent can be forced to load any event model via	2361	AnyEvent can be forced to load any event model via
…		…
1022	specified in the variable.	2366	specified in the variable.
1023		2367
1024	You can make AnyEvent completely ignore this variable by deleting it	2368	You can make AnyEvent completely ignore this variable by deleting it
1025	before the first watcher gets created, e.g. with a C<BEGIN> block:	2369	before the first watcher gets created, e.g. with a C<BEGIN> block:
1026		2370
1027	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2371	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1028		2372
1029	use AnyEvent;	2373	use AnyEvent;
		2374
		2375	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		2376	be used to probe what backend is used and gain other information (which is
		2377	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2378	$ENV{PERL_ANYEVENT_STRICT}.
		2379
		2380	Note that AnyEvent will remove I<all> environment variables starting with
		2381	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2382	enabled.
		2383
		2384
		2385	=head1 BUGS
		2386
		2387	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2388	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2389	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2390	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2391	pronounced).
1030		2392
1031		2393
1032	=head1 SEE ALSO	2394	=head1 SEE ALSO
1033		2395
1034	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	2396	Utility functions: L<AnyEvent::Util>.
1035	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	2397
		2398	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1036	L<Event::Lib>, L<Qt>, L<POE>.	2399	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1037		2400
1038	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	2401	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1039	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	2402	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1040	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	2403	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1041	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	2404	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1042		2405
		2406	Non-blocking file handles, sockets, TCP clients and
		2407	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
		2408
		2409	Asynchronous DNS: L<AnyEvent::DNS>.
		2410
		2411	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2412	L<Coro::Event>,
		2413
1043	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	2414	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2415	L<AnyEvent::HTTP>.
1044		2416
1045		2417
1046	=head1 AUTHOR	2418	=head1 AUTHOR
1047		2419
1048	Marc Lehmann <schmorp@schmorp.de>	2420	Marc Lehmann <schmorp@schmorp.de>
1049	http://home.schmorp.de/	2421	http://home.schmorp.de/
1050		2422
1051	=cut	2423	=cut
1052		2424
1053	1	2425	1
1054		2426

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