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Revision 1.106 by root, Thu May 1 13:45:22 2008 UTC vs.
Revision 1.249 by root, Mon Jul 20 06:00:42 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 ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->send; # 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		108
71	=head1 DESCRIPTION	109	=head1 DESCRIPTION
72		110
…		…
78	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>
79	module.	117	module.
80		118
81	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
82	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
83	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	121	following modules is already loaded: L<EV>,
84	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>,
85	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
86	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
87	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
88	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
…		…
102	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
103	use AnyEvent so their modules work together with others seamlessly...	141	use AnyEvent so their modules work together with others seamlessly...
104		142
105	The pure-perl implementation of AnyEvent is called	143	The pure-perl implementation of AnyEvent is called
106	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
107	explicitly.	145	explicitly and enjoy the high availability of that event loop :)
108		146
109	=head1 WATCHERS	147	=head1 WATCHERS
110		148
111	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
112	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
113	the callback to call, the filehandle to watch, etc.	151	the callback to call, the file handle to watch, etc.
114		152
115	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
116	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
117	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
118	is in control).	156	is in control).
119		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
120	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
121	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
122	to it).	166	to it).
123		167
124	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.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	170	Many watchers either are used with "recursion" (repeating timers for
127	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.
128		172
129	An any way to achieve that is this pattern:	173	An any way to achieve that is this pattern:
130		174
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	175	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	176	# you can use $w here, for example to undef it
133	undef $w;	177	undef $w;
134	});	178	});
135		179
136	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,
137	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
138	declared.	182	declared.
139		183
140	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
141		185
142	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
143	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
144		188
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	189	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		190	for events (AnyEvent might or might not keep a reference to this file
		191	handle). Note that only file handles pointing to things for which
		192	non-blocking operation makes sense are allowed. This includes sockets,
		193	most character devices, pipes, fifos and so on, but not for example files
		194	or block devices.
		195
146	for events. C<poll> must be a string that is either C<r> or C<w>,	196	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
148	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.
149	becomes ready.
150		200
151	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
154		204
…		…
158		208
159	Some event loops issue spurious readyness notifications, so you should	209	Some event loops issue spurious readyness notifications, so you should
160	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
161	handles.	211	handles.
162		212
163	Example:
164
165	# 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
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	216	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	217	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	218	warn "read: $input\n";
169	undef $w;	219	undef $w;
170	});	220	});
…		…
180		230
181	Although the callback might get passed parameters, their value and	231	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	232	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	233	callbacks cannot use arguments passed to time watcher callbacks.
184		234
185	The timer callback will be invoked at most once: if you want a repeating	235	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	236	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	237	callback will be invoked regularly at that interval (in fractional
		238	seconds) after the first invocation. If C<interval> is specified with a
		239	false value, then it is treated as if it were missing.
188		240
189	Example:	241	The callback will be rescheduled before invoking the callback, but no
		242	attempt is done to avoid timer drift in most backends, so the interval is
		243	only approximate.
190		244
191	# fire an event after 7.7 seconds	245	Example: fire an event after 7.7 seconds.
		246
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	247	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	248	warn "timeout\n";
194	});	249	});
195		250
196	# to cancel the timer:	251	# to cancel the timer:
197	undef $w;	252	undef $w;
198		253
199	Example 2:
200
201	# 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.
202	my $w;
203		255
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	256	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		257	warn "timeout\n";
207	};	258	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		259
212	=head3 TIMING ISSUES	260	=head3 TIMING ISSUES
213		261
214	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
215	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
…		…
227	timers.	275	timers.
228		276
229	AnyEvent always prefers relative timers, if available, matching the	277	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	278	AnyEvent API.
231		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
232	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
233		359
234	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
235	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
236	be invoked whenever a signal occurs.	362	callback to be invoked whenever a signal occurs.
237		363
238	Although the callback might get passed parameters, their value and	364	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	365	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	366	callbacks cannot use arguments passed to signal watcher callbacks.
241		367
242	Multiple signal occurances can be clumped together into one callback	368	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
244	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,
245	but it is guarenteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
246		372
247	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
248	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
249		376
250	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
251	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
252		380
253	Example: exit on SIGINT	381	Example: exit on SIGINT
254		382
255	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
256		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$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
257	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
258		402
259	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.
260		404
261	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
262	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
263	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
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	409
266	you I<can> rely on child watcher callback arguments.	410	The callback will be called with the pid and exit status (as returned by
		411	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		412	callback arguments.
		413
		414	This watcher type works by installing a signal handler for C<SIGCHLD>,
		415	and since it cannot be shared, nothing else should use SIGCHLD or reap
		416	random child processes (waiting for specific child processes, e.g. inside
		417	C<system>, is just fine).
267		418
268	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
269	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
270	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
271		422
272	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
273	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
274	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.
275		429
276	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
277	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
278	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.
279		438
280	Example: fork a process and wait for it	439	Example: fork a process and wait for it
281		440
282	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
283		442
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	443	my $pid = fork or exit 5;
287		444
288	my $w = AnyEvent->child (	445	my $w = AnyEvent->child (
289	pid => $pid,	446	pid => $pid,
290	cb => sub {	447	cb => sub {
291	my ($pid, $status) = @_;	448	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	449	warn "pid $pid exited with status $status";
293	$done->send;	450	$done->send;
294	},	451	},
295	);	452	);
296		453
297	# do something else, then wait for process exit	454	# do something else, then wait for process exit
298	$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	});
299		491
300	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
301		493
302	If you are familiar with some event loops you will know that all of them	494	If you are familiar with some event loops you will know that all of them
303	require you to run some blocking "loop", "run" or similar function that	495	require you to run some blocking "loop", "run" or similar function that
304	will actively watch for new events and call your callbacks.	496	will actively watch for new events and call your callbacks.
305		497
306	AnyEvent is different, it expects somebody else to run the event loop and	498	AnyEvent is slightly different: it expects somebody else to run the event
307	will only block when necessary (usually when told by the user).	499	loop and will only block when necessary (usually when told by the user).
308		500
309	The instrument to do that is called a "condition variable", so called	501	The instrument to do that is called a "condition variable", so called
310	because they represent a condition that must become true.	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.
311		505
312	Condition variables can be created by calling the C<< AnyEvent->condvar	506	Condition variables can be created by calling the C<< AnyEvent->condvar
313	>> method, usually without arguments. The only argument pair allowed is	507	>> method, usually without arguments. The only argument pair allowed is
314	C<cb>, which specifies a callback to be called when the condition variable	508	C<cb>, which specifies a callback to be called when the condition variable
315	becomes true.	509	becomes true, with the condition variable as the first argument (but not
		510	the results).
316		511
317	After creation, the conditon variable is "false" until it becomes "true"	512	After creation, the condition variable is "false" until it becomes "true"
318	by calling the C<send> method.	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).
319		516
320	Condition variables are similar to callbacks, except that you can	517	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	518	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstandign events have been processed. And yet	519	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transations - each condition variable can be	520	another way to call them is transactions - each condition variable can be
324	used to represent a transaction, which finishes at some point and delivers	521	used to represent a transaction, which finishes at some point and delivers
325	a result.	522	a result.
326		523
327	Condition variables are very useful to signal that something has finished,	524	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	525	for example, if you write a module that does asynchronous http requests,
329	then a condition variable would be the ideal candidate to signal the	526	then a condition variable would be the ideal candidate to signal the
330	availability of results. The user can either act when the callback is	527	availability of results. The user can either act when the callback is
331	called or can synchronously C<< ->wait >> for the results.	528	called or can synchronously C<< ->recv >> for the results.
332		529
333	You can also use them to simulate traditional event loops - for example,	530	You can also use them to simulate traditional event loops - for example,
334	you can block your main program until an event occurs - for example, you	531	you can block your main program until an event occurs - for example, you
335	could C<< ->wait >> in your main program until the user clicks the Quit	532	could C<< ->recv >> in your main program until the user clicks the Quit
336	button of your app, which would C<< ->send >> the "quit" event.	533	button of your app, which would C<< ->send >> the "quit" event.
337		534
338	Note that condition variables recurse into the event loop - if you have	535	Note that condition variables recurse into the event loop - if you have
339	two pieces of code that call C<< ->wait >> in a round-robbin fashion, you	536	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
340	lose. Therefore, condition variables are good to export to your caller, but	537	lose. Therefore, condition variables are good to export to your caller, but
341	you should avoid making a blocking wait yourself, at least in callbacks,	538	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	539	as this asks for trouble.
343		540
344	Condition variables are represented by hash refs in perl, and the keys	541	Condition variables are represented by hash refs in perl, and the keys
…		…
349		546
350	There are two "sides" to a condition variable - the "producer side" which	547	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> send >>, and the "consumer side", which waits	548	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the send to occur.	549	for the send to occur.
353		550
354	Example:	551	Example: wait for a timer.
355		552
356	# wait till the result is ready	553	# wait till the result is ready
357	my $result_ready = AnyEvent->condvar;	554	my $result_ready = AnyEvent->condvar;
358		555
359	# do something such as adding a timer	556	# do something such as adding a timer
…		…
364	after => 1,	561	after => 1,
365	cb => sub { $result_ready->send },	562	cb => sub { $result_ready->send },
366	);	563	);
367		564
368	# this "blocks" (while handling events) till the callback	565	# this "blocks" (while handling events) till the callback
369	# calls send	566	# calls -<send
370	$result_ready->wait;	567	$result_ready->recv;
		568
		569	Example: wait for a timer, but take advantage of the fact that condition
		570	variables are also callable directly.
		571
		572	my $done = AnyEvent->condvar;
		573	my $delay = AnyEvent->timer (after => 5, cb => $done);
		574	$done->recv;
		575
		576	Example: Imagine an API that returns a condvar and doesn't support
		577	callbacks. This is how you make a synchronous call, for example from
		578	the main program:
		579
		580	use AnyEvent::CouchDB;
		581
		582	...
		583
		584	my @info = $couchdb->info->recv;
		585
		586	And this is how you would just set a callback to be called whenever the
		587	results are available:
		588
		589	$couchdb->info->cb (sub {
		590	my @info = $_[0]->recv;
		591	});
371		592
372	=head3 METHODS FOR PRODUCERS	593	=head3 METHODS FOR PRODUCERS
373		594
374	These methods should only be used by the producing side, i.e. the	595	These methods should only be used by the producing side, i.e. the
375	code/module that eventually sends the signal. Note that it is also	596	code/module that eventually sends the signal. Note that it is also
…		…
378		599
379	=over 4	600	=over 4
380		601
381	=item $cv->send (...)	602	=item $cv->send (...)
382		603
383	Flag the condition as ready - a running C<< ->wait >> and all further	604	Flag the condition as ready - a running C<< ->recv >> and all further
384	calls to C<wait> will (eventually) return after this method has been	605	calls to C<recv> will (eventually) return after this method has been
385	called. If nobody is waiting the send will be remembered.	606	called. If nobody is waiting the send will be remembered.
386		607
387	If a callback has been set on the condition variable, it is called	608	If a callback has been set on the condition variable, it is called
388	immediately from within send.	609	immediately from within send.
389		610
390	Any arguments passed to the C<send> call will be returned by all	611	Any arguments passed to the C<send> call will be returned by all
391	future C<< ->wait >> calls.	612	future C<< ->recv >> calls.
		613
		614	Condition variables are overloaded so one can call them directly (as if
		615	they were a code reference). Calling them directly is the same as calling
		616	C<send>.
392		617
393	=item $cv->croak ($error)	618	=item $cv->croak ($error)
394		619
395	Similar to send, but causes all call's wait C<< ->wait >> to invoke	620	Similar to send, but causes all call's to C<< ->recv >> to invoke
396	C<Carp::croak> with the given error message/object/scalar.	621	C<Carp::croak> with the given error message/object/scalar.
397		622
398	This can be used to signal any errors to the condition variable	623	This can be used to signal any errors to the condition variable
399	user/consumer.	624	user/consumer. Doing it this way instead of calling C<croak> directly
		625	delays the error detetcion, but has the overwhelmign advantage that it
		626	diagnoses the error at the place where the result is expected, and not
		627	deep in some event clalback without connection to the actual code causing
		628	the problem.
400		629
401	=item $cv->begin ([group callback])	630	=item $cv->begin ([group callback])
402		631
403	=item $cv->end	632	=item $cv->end
404		633
…		…
410	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	639	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
411	>>, the (last) callback passed to C<begin> will be executed. That callback	640	>>, the (last) callback passed to C<begin> will be executed. That callback
412	is I<supposed> to call C<< ->send >>, but that is not required. If no	641	is I<supposed> to call C<< ->send >>, but that is not required. If no
413	callback was set, C<send> will be called without any arguments.	642	callback was set, C<send> will be called without any arguments.
414		643
415	Let's clarify this with the ping example:	644	You can think of C<< $cv->send >> giving you an OR condition (one call
		645	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		646	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		647
		648	Let's start with a simple example: you have two I/O watchers (for example,
		649	STDOUT and STDERR for a program), and you want to wait for both streams to
		650	close before activating a condvar:
		651
		652	my $cv = AnyEvent->condvar;
		653
		654	$cv->begin; # first watcher
		655	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		656	defined sysread $fh1, my $buf, 4096
		657	or $cv->end;
		658	});
		659
		660	$cv->begin; # second watcher
		661	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		662	defined sysread $fh2, my $buf, 4096
		663	or $cv->end;
		664	});
		665
		666	$cv->recv;
		667
		668	This works because for every event source (EOF on file handle), there is
		669	one call to C<begin>, so the condvar waits for all calls to C<end> before
		670	sending.
		671
		672	The ping example mentioned above is slightly more complicated, as the
		673	there are results to be passwd back, and the number of tasks that are
		674	begung can potentially be zero:
416		675
417	my $cv = AnyEvent->condvar;	676	my $cv = AnyEvent->condvar;
418		677
419	my %result;	678	my %result;
420	$cv->begin (sub { $cv->send (\%result) });	679	$cv->begin (sub { $cv->send (\%result) });
…		…
440	loop, which serves two important purposes: first, it sets the callback	699	loop, which serves two important purposes: first, it sets the callback
441	to be called once the counter reaches C<0>, and second, it ensures that	700	to be called once the counter reaches C<0>, and second, it ensures that
442	C<send> is called even when C<no> hosts are being pinged (the loop	701	C<send> is called even when C<no> hosts are being pinged (the loop
443	doesn't execute once).	702	doesn't execute once).
444		703
445	This is the general pattern when you "fan out" into multiple subrequests:	704	This is the general pattern when you "fan out" into multiple (but
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	705	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
447	is called at least once, and then, for each subrequest you start, call	706	the callback and ensure C<end> is called at least once, and then, for each
448	C<begin> and for eahc subrequest you finish, call C<end>.	707	subrequest you start, call C<begin> and for each subrequest you finish,
		708	call C<end>.
449		709
450	=back	710	=back
451		711
452	=head3 METHODS FOR CONSUMERS	712	=head3 METHODS FOR CONSUMERS
453		713
454	These methods should only be used by the consuming side, i.e. the	714	These methods should only be used by the consuming side, i.e. the
455	code awaits the condition.	715	code awaits the condition.
456		716
457	=over 4	717	=over 4
458		718
459	=item $cv->wait	719	=item $cv->recv
460		720
461	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	721	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
462	>> methods have been called on c<$cv>, while servicing other watchers	722	>> methods have been called on c<$cv>, while servicing other watchers
463	normally.	723	normally.
464		724
…		…
469	function will call C<croak>.	729	function will call C<croak>.
470		730
471	In list context, all parameters passed to C<send> will be returned,	731	In list context, all parameters passed to C<send> will be returned,
472	in scalar context only the first one will be returned.	732	in scalar context only the first one will be returned.
473		733
		734	Note that doing a blocking wait in a callback is not supported by any
		735	event loop, that is, recursive invocation of a blocking C<< ->recv
		736	>> is not allowed, and the C<recv> call will C<croak> if such a
		737	condition is detected. This condition can be slightly loosened by using
		738	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		739	any thread that doesn't run the event loop itself.
		740
474	Not all event models support a blocking wait - some die in that case	741	Not all event models support a blocking wait - some die in that case
475	(programs might want to do that to stay interactive), so I<if you are	742	(programs might want to do that to stay interactive), so I<if you are
476	using this from a module, never require a blocking wait>, but let the	743	using this from a module, never require a blocking wait>. Instead, let the
477	caller decide whether the call will block or not (for example, by coupling	744	caller decide whether the call will block or not (for example, by coupling
478	condition variables with some kind of request results and supporting	745	condition variables with some kind of request results and supporting
479	callbacks so the caller knows that getting the result will not block,	746	callbacks so the caller knows that getting the result will not block,
480	while still suppporting blocking waits if the caller so desires).	747	while still supporting blocking waits if the caller so desires).
481		748
482	Another reason I<never> to C<< ->wait >> in a module is that you cannot
483	sensibly have two C<< ->wait >>'s in parallel, as that would require
484	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
486	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
487	from different coroutines, however).
488
489	You can ensure that C<< -wait >> never blocks by setting a callback and	749	You can ensure that C<< -recv >> never blocks by setting a callback and
490	only calling C<< ->wait >> from within that callback (or at a later	750	only calling C<< ->recv >> from within that callback (or at a later
491	time). This will work even when the event loop does not support blocking	751	time). This will work even when the event loop does not support blocking
492	waits otherwise.	752	waits otherwise.
493		753
494	=item $bool = $cv->ready	754	=item $bool = $cv->ready
495		755
496	Returns true when the condition is "true", i.e. whether C<send> or	756	Returns true when the condition is "true", i.e. whether C<send> or
497	C<croak> have been called.	757	C<croak> have been called.
498		758
499	=item $cb = $cv->cb ([new callback])	759	=item $cb = $cv->cb ($cb->($cv))
500		760
501	This is a mutator function that returns the callback set and optionally	761	This is a mutator function that returns the callback set and optionally
502	replaces it before doing so.	762	replaces it before doing so.
503		763
504	The callback will be called when the condition becomes "true", i.e. when	764	The callback will be called when the condition becomes "true", i.e. when
505	C<send> or C<croak> are called. Calling C<wait> inside the callback	765	C<send> or C<croak> are called, with the only argument being the condition
506	or at any later time is guaranteed not to block.	766	variable itself. Calling C<recv> inside the callback or at any later time
		767	is guaranteed not to block.
507		768
508	=back	769	=back
509		770
		771	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		772
		773	The available backend classes are (every class has its own manpage):
		774
		775	=over 4
		776
		777	=item Backends that are autoprobed when no other event loop can be found.
		778
		779	EV is the preferred backend when no other event loop seems to be in
		780	use. If EV is not installed, then AnyEvent will try Event, and, failing
		781	that, will fall back to its own pure-perl implementation, which is
		782	available everywhere as it comes with AnyEvent itself.
		783
		784	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		785	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		786	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		787
		788	=item Backends that are transparently being picked up when they are used.
		789
		790	These will be used when they are currently loaded when the first watcher
		791	is created, in which case it is assumed that the application is using
		792	them. This means that AnyEvent will automatically pick the right backend
		793	when the main program loads an event module before anything starts to
		794	create watchers. Nothing special needs to be done by the main program.
		795
		796	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		797	AnyEvent::Impl::Tk based on Tk, very broken.
		798	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		799	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		800
		801	=item Backends with special needs.
		802
		803	Qt requires the Qt::Application to be instantiated first, but will
		804	otherwise be picked up automatically. As long as the main program
		805	instantiates the application before any AnyEvent watchers are created,
		806	everything should just work.
		807
		808	AnyEvent::Impl::Qt based on Qt.
		809
		810	Support for IO::Async can only be partial, as it is too broken and
		811	architecturally limited to even support the AnyEvent API. It also
		812	is the only event loop that needs the loop to be set explicitly, so
		813	it can only be used by a main program knowing about AnyEvent. See
		814	L<AnyEvent::Impl::Async> for the gory details.
		815
		816	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		817
		818	=item Event loops that are indirectly supported via other backends.
		819
		820	Some event loops can be supported via other modules:
		821
		822	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		823
		824	B<WxWidgets> has no support for watching file handles. However, you can
		825	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		826	polls 20 times per second, which was considered to be too horrible to even
		827	consider for AnyEvent.
		828
		829	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		830	backend, so it can be supported through POE.
		831
		832	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		833	load L<POE> when detecting them, in the hope that POE will pick them up,
		834	in which case everything will be automatic.
		835
		836	=back
		837
510	=head1 GLOBAL VARIABLES AND FUNCTIONS	838	=head1 GLOBAL VARIABLES AND FUNCTIONS
511		839
		840	These are not normally required to use AnyEvent, but can be useful to
		841	write AnyEvent extension modules.
		842
512	=over 4	843	=over 4
513		844
514	=item $AnyEvent::MODEL	845	=item $AnyEvent::MODEL
515		846
516	Contains C<undef> until the first watcher is being created. Then it	847	Contains C<undef> until the first watcher is being created, before the
		848	backend has been autodetected.
		849
517	contains the event model that is being used, which is the name of the	850	Afterwards it contains the event model that is being used, which is the
518	Perl class implementing the model. This class is usually one of the	851	name of the Perl class implementing the model. This class is usually one
519	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	852	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
520	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	853	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
521		854	will be C<urxvt::anyevent>).
522	The known classes so far are:
523
524	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
525	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
526	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
527	AnyEvent::Impl::Event based on Event, second best choice.
528	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
529	AnyEvent::Impl::Glib based on Glib, third-best choice.
530	AnyEvent::Impl::Tk based on Tk, very bad choice.
531	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
532	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
533	AnyEvent::Impl::POE based on POE, not generic enough for full support.
534
535	There is no support for WxWidgets, as WxWidgets has no support for
536	watching file handles. However, you can use WxWidgets through the
537	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
538	second, which was considered to be too horrible to even consider for
539	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
540	it's adaptor.
541
542	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
543	autodetecting them.
544		855
545	=item AnyEvent::detect	856	=item AnyEvent::detect
546		857
547	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	858	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
548	if necessary. You should only call this function right before you would	859	if necessary. You should only call this function right before you would
549	have created an AnyEvent watcher anyway, that is, as late as possible at	860	have created an AnyEvent watcher anyway, that is, as late as possible at
550	runtime.	861	runtime, and not e.g. while initialising of your module.
		862
		863	If you need to do some initialisation before AnyEvent watchers are
		864	created, use C<post_detect>.
		865
		866	=item $guard = AnyEvent::post_detect { BLOCK }
		867
		868	Arranges for the code block to be executed as soon as the event model is
		869	autodetected (or immediately if this has already happened).
		870
		871	The block will be executed I<after> the actual backend has been detected
		872	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		873	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		874	other initialisations - see the sources of L<AnyEvent::Strict> or
		875	L<AnyEvent::AIO> to see how this is used.
		876
		877	The most common usage is to create some global watchers, without forcing
		878	event module detection too early, for example, L<AnyEvent::AIO> creates
		879	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		880	avoid autodetecting the event module at load time.
		881
		882	If called in scalar or list context, then it creates and returns an object
		883	that automatically removes the callback again when it is destroyed. See
		884	L<Coro::BDB> for a case where this is useful.
		885
		886	=item @AnyEvent::post_detect
		887
		888	If there are any code references in this array (you can C<push> to it
		889	before or after loading AnyEvent), then they will called directly after
		890	the event loop has been chosen.
		891
		892	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		893	if it is defined then the event loop has already been detected, and the
		894	array will be ignored.
		895
		896	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		897	it,as it takes care of these details.
		898
		899	This variable is mainly useful for modules that can do something useful
		900	when AnyEvent is used and thus want to know when it is initialised, but do
		901	not need to even load it by default. This array provides the means to hook
		902	into AnyEvent passively, without loading it.
551		903
552	=back	904	=back
553		905
554	=head1 WHAT TO DO IN A MODULE	906	=head1 WHAT TO DO IN A MODULE
555		907
…		…
559	Be careful when you create watchers in the module body - AnyEvent will	911	Be careful when you create watchers in the module body - AnyEvent will
560	decide which event module to use as soon as the first method is called, so	912	decide which event module to use as soon as the first method is called, so
561	by calling AnyEvent in your module body you force the user of your module	913	by calling AnyEvent in your module body you force the user of your module
562	to load the event module first.	914	to load the event module first.
563		915
564	Never call C<< ->wait >> on a condition variable unless you I<know> that	916	Never call C<< ->recv >> on a condition variable unless you I<know> that
565	the C<< ->send >> method has been called on it already. This is	917	the C<< ->send >> method has been called on it already. This is
566	because it will stall the whole program, and the whole point of using	918	because it will stall the whole program, and the whole point of using
567	events is to stay interactive.	919	events is to stay interactive.
568		920
569	It is fine, however, to call C<< ->wait >> when the user of your module	921	It is fine, however, to call C<< ->recv >> when the user of your module
570	requests it (i.e. if you create a http request object ad have a method	922	requests it (i.e. if you create a http request object ad have a method
571	called C<results> that returns the results, it should call C<< ->wait >>	923	called C<results> that returns the results, it should call C<< ->recv >>
572	freely, as the user of your module knows what she is doing. always).	924	freely, as the user of your module knows what she is doing. always).
573		925
574	=head1 WHAT TO DO IN THE MAIN PROGRAM	926	=head1 WHAT TO DO IN THE MAIN PROGRAM
575		927
576	There will always be a single main program - the only place that should	928	There will always be a single main program - the only place that should
…		…
578		930
579	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	931	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
580	do anything special (it does not need to be event-based) and let AnyEvent	932	do anything special (it does not need to be event-based) and let AnyEvent
581	decide which implementation to chose if some module relies on it.	933	decide which implementation to chose if some module relies on it.
582		934
583	If the main program relies on a specific event model. For example, in	935	If the main program relies on a specific event model - for example, in
584	Gtk2 programs you have to rely on the Glib module. You should load the	936	Gtk2 programs you have to rely on the Glib module - you should load the
585	event module before loading AnyEvent or any module that uses it: generally	937	event module before loading AnyEvent or any module that uses it: generally
586	speaking, you should load it as early as possible. The reason is that	938	speaking, you should load it as early as possible. The reason is that
587	modules might create watchers when they are loaded, and AnyEvent will	939	modules might create watchers when they are loaded, and AnyEvent will
588	decide on the event model to use as soon as it creates watchers, and it	940	decide on the event model to use as soon as it creates watchers, and it
589	might chose the wrong one unless you load the correct one yourself.	941	might chose the wrong one unless you load the correct one yourself.
590		942
591	You can chose to use a rather inefficient pure-perl implementation by	943	You can chose to use a pure-perl implementation by loading the
592	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	944	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
593	behaviour everywhere, but letting AnyEvent chose is generally better.	945	everywhere, but letting AnyEvent chose the model is generally better.
		946
		947	=head2 MAINLOOP EMULATION
		948
		949	Sometimes (often for short test scripts, or even standalone programs who
		950	only want to use AnyEvent), you do not want to run a specific event loop.
		951
		952	In that case, you can use a condition variable like this:
		953
		954	AnyEvent->condvar->recv;
		955
		956	This has the effect of entering the event loop and looping forever.
		957
		958	Note that usually your program has some exit condition, in which case
		959	it is better to use the "traditional" approach of storing a condition
		960	variable somewhere, waiting for it, and sending it when the program should
		961	exit cleanly.
		962
594		963
595	=head1 OTHER MODULES	964	=head1 OTHER MODULES
596		965
597	The following is a non-exhaustive list of additional modules that use	966	The following is a non-exhaustive list of additional modules that use
598	AnyEvent and can therefore be mixed easily with other AnyEvent modules	967	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
599	in the same program. Some of the modules come with AnyEvent, some are	968	modules and other event loops in the same program. Some of the modules
600	available via CPAN.	969	come with AnyEvent, most are available via CPAN.
601		970
602	=over 4	971	=over 4
603		972
604	=item L<AnyEvent::Util>	973	=item L<AnyEvent::Util>
605		974
606	Contains various utility functions that replace often-used but blocking	975	Contains various utility functions that replace often-used but blocking
607	functions such as C<inet_aton> by event-/callback-based versions.	976	functions such as C<inet_aton> by event-/callback-based versions.
608		977
		978	=item L<AnyEvent::Socket>
		979
		980	Provides various utility functions for (internet protocol) sockets,
		981	addresses and name resolution. Also functions to create non-blocking tcp
		982	connections or tcp servers, with IPv6 and SRV record support and more.
		983
609	=item L<AnyEvent::Handle>	984	=item L<AnyEvent::Handle>
610		985
611	Provide read and write buffers and manages watchers for reads and writes.	986	Provide read and write buffers, manages watchers for reads and writes,
		987	supports raw and formatted I/O, I/O queued and fully transparent and
		988	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
612		989
613	=item L<AnyEvent::Socket>	990	=item L<AnyEvent::DNS>
614		991
615	Provides a means to do non-blocking connects, accepts etc.	992	Provides rich asynchronous DNS resolver capabilities.
		993
		994	=item L<AnyEvent::HTTP>
		995
		996	A simple-to-use HTTP library that is capable of making a lot of concurrent
		997	HTTP requests.
616		998
617	=item L<AnyEvent::HTTPD>	999	=item L<AnyEvent::HTTPD>
618		1000
619	Provides a simple web application server framework.	1001	Provides a simple web application server framework.
620		1002
621	=item L<AnyEvent::DNS>
622
623	Provides asynchronous DNS resolver capabilities, beyond what
624	L<AnyEvent::Util> offers.
625
626	=item L<AnyEvent::FastPing>	1003	=item L<AnyEvent::FastPing>
627		1004
628	The fastest ping in the west.	1005	The fastest ping in the west.
629		1006
		1007	=item L<AnyEvent::DBI>
		1008
		1009	Executes L<DBI> requests asynchronously in a proxy process.
		1010
		1011	=item L<AnyEvent::AIO>
		1012
		1013	Truly asynchronous I/O, should be in the toolbox of every event
		1014	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1015	together.
		1016
		1017	=item L<AnyEvent::BDB>
		1018
		1019	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1020	L<BDB> and AnyEvent together.
		1021
		1022	=item L<AnyEvent::GPSD>
		1023
		1024	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1025
630	=item L<Net::IRC3>	1026	=item L<AnyEvent::IRC>
631		1027
632	AnyEvent based IRC client module family.	1028	AnyEvent based IRC client module family (replacing the older Net::IRC3).
633		1029
634	=item L<Net::XMPP2>	1030	=item L<AnyEvent::XMPP>
635		1031
636	AnyEvent based XMPP (Jabber protocol) module family.	1032	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1033	Net::XMPP2>.
		1034
		1035	=item L<AnyEvent::IGS>
		1036
		1037	A non-blocking interface to the Internet Go Server protocol (used by
		1038	L<App::IGS>).
637		1039
638	=item L<Net::FCP>	1040	=item L<Net::FCP>
639		1041
640	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1042	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
641	of AnyEvent.	1043	of AnyEvent.
…		…
644		1046
645	High level API for event-based execution flow control.	1047	High level API for event-based execution flow control.
646		1048
647	=item L<Coro>	1049	=item L<Coro>
648		1050
649	Has special support for AnyEvent.	1051	Has special support for AnyEvent via L<Coro::AnyEvent>.
650
651	=item L<IO::Lambda>
652
653	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
654
655	=item L<IO::AIO>
656
657	Truly asynchronous I/O, should be in the toolbox of every event
658	programmer. Can be trivially made to use AnyEvent.
659
660	=item L<BDB>
661
662	Truly asynchronous Berkeley DB access. Can be trivially made to use
663	AnyEvent.
664		1052
665	=back	1053	=back
666		1054
667	=cut	1055	=cut
668		1056
669	package AnyEvent;	1057	package AnyEvent;
670		1058
		1059	# basically a tuned-down version of common::sense
		1060	sub common_sense {
671	no warnings;	1061	# no warnings
672	use strict;	1062	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1063	# use strict vars subs
		1064	$^H |= 0x00000600;
		1065	}
673		1066
		1067	BEGIN { AnyEvent::common_sense }
		1068
674	use Carp;	1069	use Carp ();
675		1070
676	our $VERSION = '3.3';	1071	our $VERSION = 4.85;
677	our $MODEL;	1072	our $MODEL;
678		1073
679	our $AUTOLOAD;	1074	our $AUTOLOAD;
680	our @ISA;	1075	our @ISA;
681		1076
682	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
683
684	our @REGISTRY;	1077	our @REGISTRY;
685		1078
		1079	our $WIN32;
		1080
		1081	our $VERBOSE;
		1082
		1083	BEGIN {
		1084	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		1085	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1086
		1087	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1088	if ${^TAINT};
		1089
		1090	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1091
		1092	}
		1093
		1094	our $MAX_SIGNAL_LATENCY = 10;
		1095
		1096	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		1097
		1098	{
		1099	my $idx;
		1100	$PROTOCOL{$_} = ++$idx
		1101	for reverse split /\s*,\s*/,
		1102	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		1103	}
		1104
686	my @models = (	1105	my @models = (
687	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
688	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
689	[EV:: => AnyEvent::Impl::EV::],	1106	[EV:: => AnyEvent::Impl::EV::],
690	[Event:: => AnyEvent::Impl::Event::],	1107	[Event:: => AnyEvent::Impl::Event::],
		1108	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		1109	# everything below here will not be autoprobed
		1110	# as the pureperl backend should work everywhere
		1111	# and is usually faster
		1112	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1113	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
691	[Tk:: => AnyEvent::Impl::Tk::],	1114	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1115	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1116	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
692	[Wx:: => AnyEvent::Impl::POE::],	1117	[Wx:: => AnyEvent::Impl::POE::],
693	[Prima:: => AnyEvent::Impl::POE::],	1118	[Prima:: => AnyEvent::Impl::POE::],
694	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1119	# IO::Async is just too broken - we would need workarounds for its
695	# everything below here will not be autoprobed as the pureperl backend should work everywhere	1120	# byzantine signal and broken child handling, among others.
696	[Glib:: => AnyEvent::Impl::Glib::],	1121	# IO::Async is rather hard to detect, as it doesn't have any
697	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1122	# obvious default class.
698	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1123	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
699	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1124	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1125	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
700	);	1126	);
701		1127
702	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1128	our %method = map +($_ => 1),
		1129	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
		1130
		1131	our @post_detect;
		1132
		1133	sub post_detect(&) {
		1134	my ($cb) = @_;
		1135
		1136	if ($MODEL) {
		1137	$cb->();
		1138
		1139	1
		1140	} else {
		1141	push @post_detect, $cb;
		1142
		1143	defined wantarray
		1144	? bless \$cb, "AnyEvent::Util::postdetect"
		1145	: ()
		1146	}
		1147	}
		1148
		1149	sub AnyEvent::Util::postdetect::DESTROY {
		1150	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1151	}
703		1152
704	sub detect() {	1153	sub detect() {
705	unless ($MODEL) {	1154	unless ($MODEL) {
706	no strict 'refs';	1155	local $SIG{__DIE__};
707		1156
708	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1157	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
709	my $model = "AnyEvent::Impl::$1";	1158	my $model = "AnyEvent::Impl::$1";
710	if (eval "require $model") {	1159	if (eval "require $model") {
711	$MODEL = $model;	1160	$MODEL = $model;
712	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1161	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
713	} else {	1162	} else {
714	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1163	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
715	}	1164	}
716	}	1165	}
717		1166
718	# check for already loaded models	1167	# check for already loaded models
719	unless ($MODEL) {	1168	unless ($MODEL) {
720	for (@REGISTRY, @models) {	1169	for (@REGISTRY, @models) {
721	my ($package, $model) = @$_;	1170	my ($package, $model) = @$_;
722	if (${"$package\::VERSION"} > 0) {	1171	if (${"$package\::VERSION"} > 0) {
723	if (eval "require $model") {	1172	if (eval "require $model") {
724	$MODEL = $model;	1173	$MODEL = $model;
725	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1174	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
726	last;	1175	last;
727	}	1176	}
728	}	1177	}
729	}	1178	}
730		1179
…		…
735	my ($package, $model) = @$_;	1184	my ($package, $model) = @$_;
736	if (eval "require $package"	1185	if (eval "require $package"
737	and ${"$package\::VERSION"} > 0	1186	and ${"$package\::VERSION"} > 0
738	and eval "require $model") {	1187	and eval "require $model") {
739	$MODEL = $model;	1188	$MODEL = $model;
740	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1189	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
741	last;	1190	last;
742	}	1191	}
743	}	1192	}
744		1193
745	$MODEL	1194	$MODEL
746	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	1195	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
747	}	1196	}
748	}	1197	}
749		1198
		1199	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1200
750	unshift @ISA, $MODEL;	1201	unshift @ISA, $MODEL;
751	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1202
		1203	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1204
		1205	(shift @post_detect)->() while @post_detect;
752	}	1206	}
753		1207
754	$MODEL	1208	$MODEL
755	}	1209	}
756		1210
757	sub AUTOLOAD {	1211	sub AUTOLOAD {
758	(my $func = $AUTOLOAD) =~ s/.*://;	1212	(my $func = $AUTOLOAD) =~ s/.*://;
759		1213
760	$method{$func}	1214	$method{$func}
761	or croak "$func: not a valid method for AnyEvent objects";	1215	or Carp::croak "$func: not a valid method for AnyEvent objects";
762		1216
763	detect unless $MODEL;	1217	detect unless $MODEL;
764		1218
765	my $class = shift;	1219	my $class = shift;
766	$class->$func (@_);	1220	$class->$func (@_);
767	}	1221	}
768		1222
		1223	# utility function to dup a filehandle. this is used by many backends
		1224	# to support binding more than one watcher per filehandle (they usually
		1225	# allow only one watcher per fd, so we dup it to get a different one).
		1226	sub _dupfh($$;$$) {
		1227	my ($poll, $fh, $r, $w) = @_;
		1228
		1229	# cygwin requires the fh mode to be matching, unix doesn't
		1230	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1231
		1232	open my $fh2, $mode, $fh
		1233	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1234
		1235	# we assume CLOEXEC is already set by perl in all important cases
		1236
		1237	($fh2, $rw)
		1238	}
		1239
769	package AnyEvent::Base;	1240	package AnyEvent::Base;
770		1241
		1242	# default implementations for many methods
		1243
		1244	sub _time {
		1245	# probe for availability of Time::HiRes
		1246	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1247	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1248	*_time = \&Time::HiRes::time;
		1249	# if (eval "use POSIX (); (POSIX::times())...
		1250	} else {
		1251	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1252	*_time = sub { time }; # epic fail
		1253	}
		1254
		1255	&_time
		1256	}
		1257
		1258	sub time { _time }
		1259	sub now { _time }
		1260	sub now_update { }
		1261
771	# default implementation for ->condvar, ->wait, ->broadcast	1262	# default implementation for ->condvar
772		1263
773	sub condvar {	1264	sub condvar {
774	bless \my $flag, "AnyEvent::Base::CondVar"	1265	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
775	}
776
777	sub AnyEvent::Base::CondVar::broadcast {
778	${$_[0]}++;
779	}
780
781	sub AnyEvent::Base::CondVar::wait {
782	AnyEvent->one_event while !${$_[0]};
783	}	1266	}
784		1267
785	# default implementation for ->signal	1268	# default implementation for ->signal
786		1269
787	our %SIG_CB;	1270	our $HAVE_ASYNC_INTERRUPT;
		1271	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1272	our (%SIG_ASY, %SIG_ASY_W);
		1273	our ($SIG_COUNT, $SIG_TW);
788		1274
		1275	sub _signal_exec {
		1276	$HAVE_ASYNC_INTERRUPT
		1277	? $SIGPIPE_R->drain
		1278	: sysread $SIGPIPE_R, my $dummy, 9;
		1279
		1280	while (%SIG_EV) {
		1281	for (keys %SIG_EV) {
		1282	delete $SIG_EV{$_};
		1283	$_->() for values %{ $SIG_CB{$_} || {} };
		1284	}
		1285	}
		1286	}
		1287
		1288	# install a dumym wakeupw atcher to reduce signal catching latency
		1289	sub _sig_add() {
		1290	unless ($SIG_COUNT++) {
		1291	# try to align timer on a full-second boundary, if possible
		1292	my $NOW = AnyEvent->now;
		1293
		1294	$SIG_TW = AnyEvent->timer (
		1295	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1296	interval => $MAX_SIGNAL_LATENCY,
		1297	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1298	);
		1299	}
		1300	}
		1301
		1302	sub _sig_del {
		1303	undef $SIG_TW
		1304	unless --$SIG_COUNT;
		1305	}
		1306
789	sub signal {	1307	sub _signal {
790	my (undef, %arg) = @_;	1308	my (undef, %arg) = @_;
791		1309
792	my $signal = uc $arg{signal}	1310	my $signal = uc $arg{signal}
793	or Carp::croak "required option 'signal' is missing";	1311	or Carp::croak "required option 'signal' is missing";
794		1312
795	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1313	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1314
		1315	if ($HAVE_ASYNC_INTERRUPT) {
		1316	# async::interrupt
		1317
		1318	$SIG_ASY{$signal} ||= do {
		1319	my $asy = new Async::Interrupt
		1320	cb => sub { undef $SIG_EV{$signal} },
		1321	signal => $signal,
		1322	pipe => [$SIGPIPE_R->filenos],
		1323	;
		1324	$asy->pipe_autodrain (0);
		1325
		1326	$asy
		1327	};
		1328
		1329	} else {
		1330	# pure perl
		1331
796	$SIG{$signal} ||= sub {	1332	$SIG{$signal} ||= sub {
797	$_->() for values %{ $SIG_CB{$signal} || {} };	1333	local $!;
		1334	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1335	undef $SIG_EV{$signal};
		1336	};
		1337
		1338	# can't do signal processing without introducing races in pure perl,
		1339	# so limit the signal latency.
		1340	_sig_add;
798	};	1341	}
799		1342
800	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1343	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
801	}	1344	}
802		1345
		1346	sub signal {
		1347	# probe for availability of Async::Interrupt
		1348	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1349	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1350
		1351	$HAVE_ASYNC_INTERRUPT = 1;
		1352	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1353	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1354
		1355	} else {
		1356	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1357
		1358	require Fcntl;
		1359
		1360	if (AnyEvent::WIN32) {
		1361	require AnyEvent::Util;
		1362
		1363	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1364	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1365	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1366	} else {
		1367	pipe $SIGPIPE_R, $SIGPIPE_W;
		1368	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1369	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1370
		1371	# not strictly required, as $^F is normally 2, but let's make sure...
		1372	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1373	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1374	}
		1375
		1376	$SIGPIPE_R
		1377	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1378
		1379	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1380	}
		1381
		1382	*signal = \&_signal;
		1383	&signal
		1384	}
		1385
803	sub AnyEvent::Base::Signal::DESTROY {	1386	sub AnyEvent::Base::signal::DESTROY {
804	my ($signal, $cb) = @{$_[0]};	1387	my ($signal, $cb) = @{$_[0]};
805		1388
		1389	_sig_del;
		1390
806	delete $SIG_CB{$signal}{$cb};	1391	delete $SIG_CB{$signal}{$cb};
807		1392
808	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1393	$HAVE_ASYNC_INTERRUPT
		1394	? delete $SIG_ASY{$signal}
		1395	: # delete doesn't work with older perls - they then
		1396	# print weird messages, or just unconditionally exit
		1397	# instead of getting the default action.
		1398	undef $SIG{$signal}
		1399	unless keys %{ $SIG_CB{$signal} };
809	}	1400	}
810		1401
811	# default implementation for ->child	1402	# default implementation for ->child
812		1403
813	our %PID_CB;	1404	our %PID_CB;
814	our $CHLD_W;	1405	our $CHLD_W;
815	our $CHLD_DELAY_W;	1406	our $CHLD_DELAY_W;
816	our $PID_IDLE;
817	our $WNOHANG;	1407	our $WNOHANG;
818		1408
819	sub _child_wait {	1409	sub _sigchld {
820	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1410	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1411	$_->($pid, $?)
821	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1412	for values %{ $PID_CB{$pid} || {} },
822	(values %{ $PID_CB{0} || {} });	1413	values %{ $PID_CB{0} || {} };
823	}	1414	}
824
825	undef $PID_IDLE;
826	}
827
828	sub _sigchld {
829	# make sure we deliver these changes "synchronous" with the event loop.
830	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
831	undef $CHLD_DELAY_W;
832	&_child_wait;
833	});
834	}	1415	}
835		1416
836	sub child {	1417	sub child {
837	my (undef, %arg) = @_;	1418	my (undef, %arg) = @_;
838		1419
839	defined (my $pid = $arg{pid} + 0)	1420	defined (my $pid = $arg{pid} + 0)
840	or Carp::croak "required option 'pid' is missing";	1421	or Carp::croak "required option 'pid' is missing";
841		1422
842	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1423	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
843		1424
844	unless ($WNOHANG) {	1425	# WNOHANG is almost cetrainly 1 everywhere
845	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1426	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
846	}	1427	? 1
		1428	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
847		1429
848	unless ($CHLD_W) {	1430	unless ($CHLD_W) {
849	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1431	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
850	# child could be a zombie already, so make at least one round	1432	# child could be a zombie already, so make at least one round
851	&_sigchld;	1433	&_sigchld;
852	}	1434	}
853		1435
854	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1436	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
855	}	1437	}
856		1438
857	sub AnyEvent::Base::Child::DESTROY {	1439	sub AnyEvent::Base::child::DESTROY {
858	my ($pid, $cb) = @{$_[0]};	1440	my ($pid, $cb) = @{$_[0]};
859		1441
860	delete $PID_CB{$pid}{$cb};	1442	delete $PID_CB{$pid}{$cb};
861	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1443	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
862		1444
863	undef $CHLD_W unless keys %PID_CB;	1445	undef $CHLD_W unless keys %PID_CB;
864	}	1446	}
		1447
		1448	# idle emulation is done by simply using a timer, regardless
		1449	# of whether the process is idle or not, and not letting
		1450	# the callback use more than 50% of the time.
		1451	sub idle {
		1452	my (undef, %arg) = @_;
		1453
		1454	my ($cb, $w, $rcb) = $arg{cb};
		1455
		1456	$rcb = sub {
		1457	if ($cb) {
		1458	$w = _time;
		1459	&$cb;
		1460	$w = _time - $w;
		1461
		1462	# never use more then 50% of the time for the idle watcher,
		1463	# within some limits
		1464	$w = 0.0001 if $w < 0.0001;
		1465	$w = 5 if $w > 5;
		1466
		1467	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1468	} else {
		1469	# clean up...
		1470	undef $w;
		1471	undef $rcb;
		1472	}
		1473	};
		1474
		1475	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1476
		1477	bless \\$cb, "AnyEvent::Base::idle"
		1478	}
		1479
		1480	sub AnyEvent::Base::idle::DESTROY {
		1481	undef $${$_[0]};
		1482	}
		1483
		1484	package AnyEvent::CondVar;
		1485
		1486	our @ISA = AnyEvent::CondVar::Base::;
		1487
		1488	package AnyEvent::CondVar::Base;
		1489
		1490	#use overload
		1491	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1492	# fallback => 1;
		1493
		1494	# save 300+ kilobytes by dirtily hardcoding overloading
		1495	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1496	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1497	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1498	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1499
		1500	our $WAITING;
		1501
		1502	sub _send {
		1503	# nop
		1504	}
		1505
		1506	sub send {
		1507	my $cv = shift;
		1508	$cv->{_ae_sent} = [@_];
		1509	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1510	$cv->_send;
		1511	}
		1512
		1513	sub croak {
		1514	$_[0]{_ae_croak} = $_[1];
		1515	$_[0]->send;
		1516	}
		1517
		1518	sub ready {
		1519	$_[0]{_ae_sent}
		1520	}
		1521
		1522	sub _wait {
		1523	$WAITING
		1524	and !$_[0]{_ae_sent}
		1525	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1526
		1527	local $WAITING = 1;
		1528	AnyEvent->one_event while !$_[0]{_ae_sent};
		1529	}
		1530
		1531	sub recv {
		1532	$_[0]->_wait;
		1533
		1534	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1535	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1536	}
		1537
		1538	sub cb {
		1539	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1540	$_[0]{_ae_cb}
		1541	}
		1542
		1543	sub begin {
		1544	++$_[0]{_ae_counter};
		1545	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1546	}
		1547
		1548	sub end {
		1549	return if --$_[0]{_ae_counter};
		1550	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1551	}
		1552
		1553	# undocumented/compatibility with pre-3.4
		1554	*broadcast = \&send;
		1555	*wait = \&_wait;
		1556
		1557	=head1 ERROR AND EXCEPTION HANDLING
		1558
		1559	In general, AnyEvent does not do any error handling - it relies on the
		1560	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1561	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1562	checking of all AnyEvent methods, however, which is highly useful during
		1563	development.
		1564
		1565	As for exception handling (i.e. runtime errors and exceptions thrown while
		1566	executing a callback), this is not only highly event-loop specific, but
		1567	also not in any way wrapped by this module, as this is the job of the main
		1568	program.
		1569
		1570	The pure perl event loop simply re-throws the exception (usually
		1571	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1572	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1573	so on.
		1574
		1575	=head1 ENVIRONMENT VARIABLES
		1576
		1577	The following environment variables are used by this module or its
		1578	submodules.
		1579
		1580	Note that AnyEvent will remove I<all> environment variables starting with
		1581	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1582	enabled.
		1583
		1584	=over 4
		1585
		1586	=item C<PERL_ANYEVENT_VERBOSE>
		1587
		1588	By default, AnyEvent will be completely silent except in fatal
		1589	conditions. You can set this environment variable to make AnyEvent more
		1590	talkative.
		1591
		1592	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1593	conditions, such as not being able to load the event model specified by
		1594	C<PERL_ANYEVENT_MODEL>.
		1595
		1596	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1597	model it chooses.
		1598
		1599	When set to C<8> or higher, then AnyEvent will report extra information on
		1600	which optional modules it loads and how it implements certain features.
		1601
		1602	=item C<PERL_ANYEVENT_STRICT>
		1603
		1604	AnyEvent does not do much argument checking by default, as thorough
		1605	argument checking is very costly. Setting this variable to a true value
		1606	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1607	check the arguments passed to most method calls. If it finds any problems,
		1608	it will croak.
		1609
		1610	In other words, enables "strict" mode.
		1611
		1612	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1613	>>, it is definitely recommended to keep it off in production. Keeping
		1614	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1615	can be very useful, however.
		1616
		1617	=item C<PERL_ANYEVENT_MODEL>
		1618
		1619	This can be used to specify the event model to be used by AnyEvent, before
		1620	auto detection and -probing kicks in. It must be a string consisting
		1621	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1622	and the resulting module name is loaded and if the load was successful,
		1623	used as event model. If it fails to load AnyEvent will proceed with
		1624	auto detection and -probing.
		1625
		1626	This functionality might change in future versions.
		1627
		1628	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1629	could start your program like this:
		1630
		1631	PERL_ANYEVENT_MODEL=Perl perl ...
		1632
		1633	=item C<PERL_ANYEVENT_PROTOCOLS>
		1634
		1635	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1636	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1637	of auto probing).
		1638
		1639	Must be set to a comma-separated list of protocols or address families,
		1640	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1641	used, and preference will be given to protocols mentioned earlier in the
		1642	list.
		1643
		1644	This variable can effectively be used for denial-of-service attacks
		1645	against local programs (e.g. when setuid), although the impact is likely
		1646	small, as the program has to handle conenction and other failures anyways.
		1647
		1648	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1649	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1650	- only support IPv4, never try to resolve or contact IPv6
		1651	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1652	IPv6, but prefer IPv6 over IPv4.
		1653
		1654	=item C<PERL_ANYEVENT_EDNS0>
		1655
		1656	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1657	for DNS. This extension is generally useful to reduce DNS traffic, but
		1658	some (broken) firewalls drop such DNS packets, which is why it is off by
		1659	default.
		1660
		1661	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1662	EDNS0 in its DNS requests.
		1663
		1664	=item C<PERL_ANYEVENT_MAX_FORKS>
		1665
		1666	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1667	will create in parallel.
		1668
		1669	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1670
		1671	The default value for the C<max_outstanding> parameter for the default DNS
		1672	resolver - this is the maximum number of parallel DNS requests that are
		1673	sent to the DNS server.
		1674
		1675	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1676
		1677	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1678	configuration) in the default resolver. When set to the empty string, no
		1679	default config will be used.
		1680
		1681	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1682
		1683	When neither C<ca_file> nor C<ca_path> was specified during
		1684	L<AnyEvent::TLS> context creation, and either of these environment
		1685	variables exist, they will be used to specify CA certificate locations
		1686	instead of a system-dependent default.
		1687
		1688	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1689
		1690	When these are set to C<1>, then the respective modules are not
		1691	loaded. Mostly good for testing AnyEvent itself.
		1692
		1693	=back
865		1694
866	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1695	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
867		1696
868	This is an advanced topic that you do not normally need to use AnyEvent in	1697	This is an advanced topic that you do not normally need to use AnyEvent in
869	a module. This section is only of use to event loop authors who want to	1698	a module. This section is only of use to event loop authors who want to
…		…
903		1732
904	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1733	I<rxvt-unicode> also cheats a bit by not providing blocking access to
905	condition variables: code blocking while waiting for a condition will	1734	condition variables: code blocking while waiting for a condition will
906	C<die>. This still works with most modules/usages, and blocking calls must	1735	C<die>. This still works with most modules/usages, and blocking calls must
907	not be done in an interactive application, so it makes sense.	1736	not be done in an interactive application, so it makes sense.
908
909	=head1 ENVIRONMENT VARIABLES
910
911	The following environment variables are used by this module:
912
913	=over 4
914
915	=item C<PERL_ANYEVENT_VERBOSE>
916
917	By default, AnyEvent will be completely silent except in fatal
918	conditions. You can set this environment variable to make AnyEvent more
919	talkative.
920
921	When set to C<1> or higher, causes AnyEvent to warn about unexpected
922	conditions, such as not being able to load the event model specified by
923	C<PERL_ANYEVENT_MODEL>.
924
925	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
926	model it chooses.
927
928	=item C<PERL_ANYEVENT_MODEL>
929
930	This can be used to specify the event model to be used by AnyEvent, before
931	autodetection and -probing kicks in. It must be a string consisting
932	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
933	and the resulting module name is loaded and if the load was successful,
934	used as event model. If it fails to load AnyEvent will proceed with
935	autodetection and -probing.
936
937	This functionality might change in future versions.
938
939	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
940	could start your program like this:
941
942	PERL_ANYEVENT_MODEL=Perl perl ...
943
944	=back
945		1737
946	=head1 EXAMPLE PROGRAM	1738	=head1 EXAMPLE PROGRAM
947		1739
948	The following program uses an I/O watcher to read data from STDIN, a timer	1740	The following program uses an I/O watcher to read data from STDIN, a timer
949	to display a message once per second, and a condition variable to quit the	1741	to display a message once per second, and a condition variable to quit the
…		…
958	poll => 'r',	1750	poll => 'r',
959	cb => sub {	1751	cb => sub {
960	warn "io event <$_[0]>\n"; # will always output <r>	1752	warn "io event <$_[0]>\n"; # will always output <r>
961	chomp (my $input = <STDIN>); # read a line	1753	chomp (my $input = <STDIN>); # read a line
962	warn "read: $input\n"; # output what has been read	1754	warn "read: $input\n"; # output what has been read
963	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1755	$cv->send if $input =~ /^q/i; # quit program if /^q/i
964	},	1756	},
965	);	1757	);
966		1758
967	my $time_watcher; # can only be used once	1759	my $time_watcher; # can only be used once
968		1760
…		…
973	});	1765	});
974	}	1766	}
975		1767
976	new_timer; # create first timer	1768	new_timer; # create first timer
977		1769
978	$cv->wait; # wait until user enters /^q/i	1770	$cv->recv; # wait until user enters /^q/i
979		1771
980	=head1 REAL-WORLD EXAMPLE	1772	=head1 REAL-WORLD EXAMPLE
981		1773
982	Consider the L<Net::FCP> module. It features (among others) the following	1774	Consider the L<Net::FCP> module. It features (among others) the following
983	API calls, which are to freenet what HTTP GET requests are to http:	1775	API calls, which are to freenet what HTTP GET requests are to http:
…		…
1033	syswrite $txn->{fh}, $txn->{request}	1825	syswrite $txn->{fh}, $txn->{request}
1034	or die "connection or write error";	1826	or die "connection or write error";
1035	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1827	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1036		1828
1037	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1829	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1038	result and signals any possible waiters that the request ahs finished:	1830	result and signals any possible waiters that the request has finished:
1039		1831
1040	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1832	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1041		1833
1042	if (end-of-file or data complete) {	1834	if (end-of-file or data complete) {
1043	$txn->{result} = $txn->{buf};	1835	$txn->{result} = $txn->{buf};
1044	$txn->{finished}->broadcast;	1836	$txn->{finished}->send;
1045	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1837	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1046	}	1838	}
1047		1839
1048	The C<result> method, finally, just waits for the finished signal (if the	1840	The C<result> method, finally, just waits for the finished signal (if the
1049	request was already finished, it doesn't wait, of course, and returns the	1841	request was already finished, it doesn't wait, of course, and returns the
1050	data:	1842	data:
1051		1843
1052	$txn->{finished}->wait;	1844	$txn->{finished}->recv;
1053	return $txn->{result};	1845	return $txn->{result};
1054		1846
1055	The actual code goes further and collects all errors (C<die>s, exceptions)	1847	The actual code goes further and collects all errors (C<die>s, exceptions)
1056	that occured during request processing. The C<result> method detects	1848	that occurred during request processing. The C<result> method detects
1057	whether an exception as thrown (it is stored inside the $txn object)	1849	whether an exception as thrown (it is stored inside the $txn object)
1058	and just throws the exception, which means connection errors and other	1850	and just throws the exception, which means connection errors and other
1059	problems get reported tot he code that tries to use the result, not in a	1851	problems get reported tot he code that tries to use the result, not in a
1060	random callback.	1852	random callback.
1061		1853
…		…
1092		1884
1093	my $quit = AnyEvent->condvar;	1885	my $quit = AnyEvent->condvar;
1094		1886
1095	$fcp->txn_client_get ($url)->cb (sub {	1887	$fcp->txn_client_get ($url)->cb (sub {
1096	...	1888	...
1097	$quit->broadcast;	1889	$quit->send;
1098	});	1890	});
1099		1891
1100	$quit->wait;	1892	$quit->recv;
1101		1893
1102		1894
1103	=head1 BENCHMARKS	1895	=head1 BENCHMARKS
1104		1896
1105	To give you an idea of the performance and overheads that AnyEvent adds	1897	To give you an idea of the performance and overheads that AnyEvent adds
…		…
1107	of various event loops I prepared some benchmarks.	1899	of various event loops I prepared some benchmarks.
1108		1900
1109	=head2 BENCHMARKING ANYEVENT OVERHEAD	1901	=head2 BENCHMARKING ANYEVENT OVERHEAD
1110		1902
1111	Here is a benchmark of various supported event models used natively and	1903	Here is a benchmark of various supported event models used natively and
1112	through anyevent. The benchmark creates a lot of timers (with a zero	1904	through AnyEvent. The benchmark creates a lot of timers (with a zero
1113	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1905	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1114	which it is), lets them fire exactly once and destroys them again.	1906	which it is), lets them fire exactly once and destroys them again.
1115		1907
1116	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1908	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1117	distribution.	1909	distribution.
…		…
1134	all watchers, to avoid adding memory overhead. That means closure creation	1926	all watchers, to avoid adding memory overhead. That means closure creation
1135	and memory usage is not included in the figures.	1927	and memory usage is not included in the figures.
1136		1928
1137	I<invoke> is the time, in microseconds, used to invoke a simple	1929	I<invoke> is the time, in microseconds, used to invoke a simple
1138	callback. The callback simply counts down a Perl variable and after it was	1930	callback. The callback simply counts down a Perl variable and after it was
1139	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1931	invoked "watcher" times, it would C<< ->send >> a condvar once to
1140	signal the end of this phase.	1932	signal the end of this phase.
1141		1933
1142	I<destroy> is the time, in microseconds, that it takes to destroy a single	1934	I<destroy> is the time, in microseconds, that it takes to destroy a single
1143	watcher.	1935	watcher.
1144		1936
1145	=head3 Results	1937	=head3 Results
1146		1938
1147	name watchers bytes create invoke destroy comment	1939	name watchers bytes create invoke destroy comment
1148	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1940	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1149	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1941	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1150	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1942	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1151	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1943	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1152	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1944	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1153	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1945	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1946	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1947	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1154	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1948	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1155	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1949	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1156	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1950	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1157	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1951	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1158		1952
1159	=head3 Discussion	1953	=head3 Discussion
1160		1954
1161	The benchmark does I<not> measure scalability of the event loop very	1955	The benchmark does I<not> measure scalability of the event loop very
1162	well. For example, a select-based event loop (such as the pure perl one)	1956	well. For example, a select-based event loop (such as the pure perl one)
…		…
1187	performance becomes really bad with lots of file descriptors (and few of	1981	performance becomes really bad with lots of file descriptors (and few of
1188	them active), of course, but this was not subject of this benchmark.	1982	them active), of course, but this was not subject of this benchmark.
1189		1983
1190	The C<Event> module has a relatively high setup and callback invocation	1984	The C<Event> module has a relatively high setup and callback invocation
1191	cost, but overall scores in on the third place.	1985	cost, but overall scores in on the third place.
		1986
		1987	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1988	when using its pure perl backend.
1192		1989
1193	C<Glib>'s memory usage is quite a bit higher, but it features a	1990	C<Glib>'s memory usage is quite a bit higher, but it features a
1194	faster callback invocation and overall ends up in the same class as	1991	faster callback invocation and overall ends up in the same class as
1195	C<Event>. However, Glib scales extremely badly, doubling the number of	1992	C<Event>. However, Glib scales extremely badly, doubling the number of
1196	watchers increases the processing time by more than a factor of four,	1993	watchers increases the processing time by more than a factor of four,
…		…
1240		2037
1241	=back	2038	=back
1242		2039
1243	=head2 BENCHMARKING THE LARGE SERVER CASE	2040	=head2 BENCHMARKING THE LARGE SERVER CASE
1244		2041
1245	This benchmark atcually benchmarks the event loop itself. It works by	2042	This benchmark actually benchmarks the event loop itself. It works by
1246	creating a number of "servers": each server consists of a socketpair, a	2043	creating a number of "servers": each server consists of a socket pair, a
1247	timeout watcher that gets reset on activity (but never fires), and an I/O	2044	timeout watcher that gets reset on activity (but never fires), and an I/O
1248	watcher waiting for input on one side of the socket. Each time the socket	2045	watcher waiting for input on one side of the socket. Each time the socket
1249	watcher reads a byte it will write that byte to a random other "server".	2046	watcher reads a byte it will write that byte to a random other "server".
1250		2047
1251	The effect is that there will be a lot of I/O watchers, only part of which	2048	The effect is that there will be a lot of I/O watchers, only part of which
1252	are active at any one point (so there is a constant number of active	2049	are active at any one point (so there is a constant number of active
1253	fds for each loop iterstaion, but which fds these are is random). The	2050	fds for each loop iteration, but which fds these are is random). The
1254	timeout is reset each time something is read because that reflects how	2051	timeout is reset each time something is read because that reflects how
1255	most timeouts work (and puts extra pressure on the event loops).	2052	most timeouts work (and puts extra pressure on the event loops).
1256		2053
1257	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	2054	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1258	(1%) are active. This mirrors the activity of large servers with many	2055	(1%) are active. This mirrors the activity of large servers with many
1259	connections, most of which are idle at any one point in time.	2056	connections, most of which are idle at any one point in time.
1260		2057
1261	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2058	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1262	distribution.	2059	distribution.
…		…
1264	=head3 Explanation of the columns	2061	=head3 Explanation of the columns
1265		2062
1266	I<sockets> is the number of sockets, and twice the number of "servers" (as	2063	I<sockets> is the number of sockets, and twice the number of "servers" (as
1267	each server has a read and write socket end).	2064	each server has a read and write socket end).
1268		2065
1269	I<create> is the time it takes to create a socketpair (which is	2066	I<create> is the time it takes to create a socket pair (which is
1270	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	2067	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1271		2068
1272	I<request>, the most important value, is the time it takes to handle a	2069	I<request>, the most important value, is the time it takes to handle a
1273	single "request", that is, reading the token from the pipe and forwarding	2070	single "request", that is, reading the token from the pipe and forwarding
1274	it to another server. This includes deleting the old timeout and creating	2071	it to another server. This includes deleting the old timeout and creating
1275	a new one that moves the timeout into the future.	2072	a new one that moves the timeout into the future.
1276		2073
1277	=head3 Results	2074	=head3 Results
1278		2075
1279	name sockets create request	2076	name sockets create request
1280	EV 20000 69.01 11.16	2077	EV 20000 69.01 11.16
1281	Perl 20000 73.32 35.87	2078	Perl 20000 73.32 35.87
		2079	IOAsync 20000 157.00 98.14 epoll
		2080	IOAsync 20000 159.31 616.06 poll
1282	Event 20000 212.62 257.32	2081	Event 20000 212.62 257.32
1283	Glib 20000 651.16 1896.30	2082	Glib 20000 651.16 1896.30
1284	POE 20000 349.67 12317.24 uses POE::Loop::Event	2083	POE 20000 349.67 12317.24 uses POE::Loop::Event
1285		2084
1286	=head3 Discussion	2085	=head3 Discussion
1287		2086
1288	This benchmark I<does> measure scalability and overall performance of the	2087	This benchmark I<does> measure scalability and overall performance of the
1289	particular event loop.	2088	particular event loop.
…		…
1291	EV is again fastest. Since it is using epoll on my system, the setup time	2090	EV is again fastest. Since it is using epoll on my system, the setup time
1292	is relatively high, though.	2091	is relatively high, though.
1293		2092
1294	Perl surprisingly comes second. It is much faster than the C-based event	2093	Perl surprisingly comes second. It is much faster than the C-based event
1295	loops Event and Glib.	2094	loops Event and Glib.
		2095
		2096	IO::Async performs very well when using its epoll backend, and still quite
		2097	good compared to Glib when using its pure perl backend.
1296		2098
1297	Event suffers from high setup time as well (look at its code and you will	2099	Event suffers from high setup time as well (look at its code and you will
1298	understand why). Callback invocation also has a high overhead compared to	2100	understand why). Callback invocation also has a high overhead compared to
1299	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2101	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1300	uses select or poll in basically all documented configurations.	2102	uses select or poll in basically all documented configurations.
…		…
1347	speed most when you have lots of watchers, not when you only have a few of	2149	speed most when you have lots of watchers, not when you only have a few of
1348	them).	2150	them).
1349		2151
1350	EV is again fastest.	2152	EV is again fastest.
1351		2153
1352	Perl again comes second. It is noticably faster than the C-based event	2154	Perl again comes second. It is noticeably faster than the C-based event
1353	loops Event and Glib, although the difference is too small to really	2155	loops Event and Glib, although the difference is too small to really
1354	matter.	2156	matter.
1355		2157
1356	POE also performs much better in this case, but is is still far behind the	2158	POE also performs much better in this case, but is is still far behind the
1357	others.	2159	others.
…		…
1360		2162
1361	=over 4	2163	=over 4
1362		2164
1363	=item * C-based event loops perform very well with small number of	2165	=item * C-based event loops perform very well with small number of
1364	watchers, as the management overhead dominates.	2166	watchers, as the management overhead dominates.
		2167
		2168	=back
		2169
		2170	=head2 THE IO::Lambda BENCHMARK
		2171
		2172	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2173	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2174	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2175	shouldn't come as a surprise to anybody). As such, the benchmark is
		2176	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2177	very optimal. But how would AnyEvent compare when used without the extra
		2178	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2179
		2180	The benchmark itself creates an echo-server, and then, for 500 times,
		2181	connects to the echo server, sends a line, waits for the reply, and then
		2182	creates the next connection. This is a rather bad benchmark, as it doesn't
		2183	test the efficiency of the framework or much non-blocking I/O, but it is a
		2184	benchmark nevertheless.
		2185
		2186	name runtime
		2187	Lambda/select 0.330 sec
		2188	+ optimized 0.122 sec
		2189	Lambda/AnyEvent 0.327 sec
		2190	+ optimized 0.138 sec
		2191	Raw sockets/select 0.077 sec
		2192	POE/select, components 0.662 sec
		2193	POE/select, raw sockets 0.226 sec
		2194	POE/select, optimized 0.404 sec
		2195
		2196	AnyEvent/select/nb 0.085 sec
		2197	AnyEvent/EV/nb 0.068 sec
		2198	+state machine 0.134 sec
		2199
		2200	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2201	benchmarks actually make blocking connects and use 100% blocking I/O,
		2202	defeating the purpose of an event-based solution. All of the newly
		2203	written AnyEvent benchmarks use 100% non-blocking connects (using
		2204	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2205	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2206	generally require a lot more bookkeeping and event handling than blocking
		2207	connects (which involve a single syscall only).
		2208
		2209	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2210	offers similar expressive power as POE and IO::Lambda, using conventional
		2211	Perl syntax. This means that both the echo server and the client are 100%
		2212	non-blocking, further placing it at a disadvantage.
		2213
		2214	As you can see, the AnyEvent + EV combination even beats the
		2215	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2216	backend easily beats IO::Lambda and POE.
		2217
		2218	And even the 100% non-blocking version written using the high-level (and
		2219	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2220	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2221	in a non-blocking way.
		2222
		2223	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2224	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2225	part of the IO::lambda distribution and were used without any changes.
		2226
		2227
		2228	=head1 SIGNALS
		2229
		2230	AnyEvent currently installs handlers for these signals:
		2231
		2232	=over 4
		2233
		2234	=item SIGCHLD
		2235
		2236	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2237	emulation for event loops that do not support them natively. Also, some
		2238	event loops install a similar handler.
		2239
		2240	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2241	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2242
		2243	=item SIGPIPE
		2244
		2245	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2246	when AnyEvent gets loaded.
		2247
		2248	The rationale for this is that AnyEvent users usually do not really depend
		2249	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2250	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2251	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2252	some random socket.
		2253
		2254	The rationale for installing a no-op handler as opposed to ignoring it is
		2255	that this way, the handler will be restored to defaults on exec.
		2256
		2257	Feel free to install your own handler, or reset it to defaults.
		2258
		2259	=back
		2260
		2261	=cut
		2262
		2263	undef $SIG{CHLD}
		2264	if $SIG{CHLD} eq 'IGNORE';
		2265
		2266	$SIG{PIPE} = sub { }
		2267	unless defined $SIG{PIPE};
		2268
		2269	=head1 RECOMMENDED/OPTIONAL MODULES
		2270
		2271	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2272	it's built-in modules) are required to use it.
		2273
		2274	That does not mean that AnyEvent won't take advantage of some additional
		2275	modules if they are installed.
		2276
		2277	This section epxlains which additional modules will be used, and how they
		2278	affect AnyEvent's operetion.
		2279
		2280	=over 4
		2281
		2282	=item L<Async::Interrupt>
		2283
		2284	This slightly arcane module is used to implement fast signal handling: To
		2285	my knowledge, there is no way to do completely race-free and quick
		2286	signal handling in pure perl. To ensure that signals still get
		2287	delivered, AnyEvent will start an interval timer to wake up perl (and
		2288	catch the signals) with some delay (default is 10 seconds, look for
		2289	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2290
		2291	If this module is available, then it will be used to implement signal
		2292	catching, which means that signals will not be delayed, and the event loop
		2293	will not be interrupted regularly, which is more efficient (And good for
		2294	battery life on laptops).
		2295
		2296	This affects not just the pure-perl event loop, but also other event loops
		2297	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2298
		2299	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2300	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2301	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2302	does nothing for those backends.
		2303
		2304	=item L<EV>
		2305
		2306	This module isn't really "optional", as it is simply one of the backend
		2307	event loops that AnyEvent can use. However, it is simply the best event
		2308	loop available in terms of features, speed and stability: It supports
		2309	the AnyEvent API optimally, implements all the watcher types in XS, does
		2310	automatic timer adjustments even when no monotonic clock is available,
		2311	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2312	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2313	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2314
		2315	=item L<Guard>
		2316
		2317	The guard module, when used, will be used to implement
		2318	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2319	lot less memory), but otherwise doesn't affect guard operation much. It is
		2320	purely used for performance.
		2321
		2322	=item L<JSON> and L<JSON::XS>
		2323
		2324	This module is required when you want to read or write JSON data via
		2325	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2326	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2327
		2328	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2329	installed.
		2330
		2331	=item L<Net::SSLeay>
		2332
		2333	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2334	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2335	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2336
		2337	=item L<Time::HiRes>
		2338
		2339	This module is part of perl since release 5.008. It will be used when the
		2340	chosen event library does not come with a timing source on it's own. The
		2341	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2342	try to use a monotonic clock for timing stability.
1365		2343
1366	=back	2344	=back
1367		2345
1368		2346
1369	=head1 FORK	2347	=head1 FORK
…		…
1371	Most event libraries are not fork-safe. The ones who are usually are	2349	Most event libraries are not fork-safe. The ones who are usually are
1372	because they rely on inefficient but fork-safe C<select> or C<poll>	2350	because they rely on inefficient but fork-safe C<select> or C<poll>
1373	calls. Only L<EV> is fully fork-aware.	2351	calls. Only L<EV> is fully fork-aware.
1374		2352
1375	If you have to fork, you must either do so I<before> creating your first	2353	If you have to fork, you must either do so I<before> creating your first
1376	watcher OR you must not use AnyEvent at all in the child.	2354	watcher OR you must not use AnyEvent at all in the child OR you must do
		2355	something completely out of the scope of AnyEvent.
1377		2356
1378		2357
1379	=head1 SECURITY CONSIDERATIONS	2358	=head1 SECURITY CONSIDERATIONS
1380		2359
1381	AnyEvent can be forced to load any event model via	2360	AnyEvent can be forced to load any event model via
…		…
1386	specified in the variable.	2365	specified in the variable.
1387		2366
1388	You can make AnyEvent completely ignore this variable by deleting it	2367	You can make AnyEvent completely ignore this variable by deleting it
1389	before the first watcher gets created, e.g. with a C<BEGIN> block:	2368	before the first watcher gets created, e.g. with a C<BEGIN> block:
1390		2369
1391	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2370	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1392		2371
1393	use AnyEvent;	2372	use AnyEvent;
		2373
		2374	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		2375	be used to probe what backend is used and gain other information (which is
		2376	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2377	$ENV{PERL_ANYEVENT_STRICT}.
		2378
		2379	Note that AnyEvent will remove I<all> environment variables starting with
		2380	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2381	enabled.
		2382
		2383
		2384	=head1 BUGS
		2385
		2386	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2387	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2388	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2389	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2390	pronounced).
1394		2391
1395		2392
1396	=head1 SEE ALSO	2393	=head1 SEE ALSO
1397		2394
1398	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	2395	Utility functions: L<AnyEvent::Util>.
1399	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	2396
		2397	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1400	L<Event::Lib>, L<Qt>, L<POE>.	2398	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1401		2399
1402	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	2400	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1403	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	2401	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1404	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	2402	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1405	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	2403	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1406		2404
		2405	Non-blocking file handles, sockets, TCP clients and
		2406	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
		2407
		2408	Asynchronous DNS: L<AnyEvent::DNS>.
		2409
		2410	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2411	L<Coro::Event>,
		2412
1407	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	2413	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2414	L<AnyEvent::HTTP>.
1408		2415
1409		2416
1410	=head1 AUTHOR	2417	=head1 AUTHOR
1411		2418
1412	Marc Lehmann <schmorp@schmorp.de>	2419	Marc Lehmann <schmorp@schmorp.de>
1413	http://home.schmorp.de/	2420	http://home.schmorp.de/
1414		2421
1415	=cut	2422	=cut
1416		2423
1417	1	2424	1
1418		2425

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