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Revision 1.56 by root, Thu Apr 24 03:10:03 2008 UTC vs.
Revision 1.388 by root, Sun Oct 2 01:22:01 2011 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt,
		6	FLTK and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# if you prefer function calls, look at the AE manpage for
		13	# an alternative API.
		14
		15	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		17
		18	# one-shot or repeating timers
		19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
		21
		22	print AnyEvent->now; # prints current event loop time
		23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		24
		25	# POSIX signal
		26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		27
		28	# child process exit
		29	my $w = AnyEvent->child (pid => $pid, cb => sub {
		30	my ($pid, $status) = @_;
12	...	31	...
13	});	32	});
14		33
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	34	# called when event loop idle (if applicable)
16	...	35	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		36
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		38	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	39	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	40	# use a condvar in callback mode:
		41	$w->cb (sub { $_[0]->recv });
		42
		43	=head1 INTRODUCTION/TUTORIAL
		44
		45	This manpage is mainly a reference manual. If you are interested
		46	in a tutorial or some gentle introduction, have a look at the
		47	L<AnyEvent::Intro> manpage.
		48
		49	=head1 SUPPORT
		50
		51	An FAQ document is available as L<AnyEvent::FAQ>.
		52
		53	There also is a mailinglist for discussing all things AnyEvent, and an IRC
		54	channel, too.
		55
		56	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		57	Repository>, at L<http://anyevent.schmorp.de>, for more info.
22		58
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		60
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	61	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
27		63
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	64	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	65	policy> and AnyEvent is I<small and efficient>.
30		66
31	First and foremost, I<AnyEvent is not an event model> itself, it only	67	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	68	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,	69	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,	70	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	71	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	72	cannot change this, but it can hide the differences between those event
		73	loops.
37		74
38	The goal of AnyEvent is to offer module authors the ability to do event	75	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	76	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	77	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	78	module users into the same thing by forcing them to use the same event
42	model you use.	79	model you use.
43		80
44	For modules like POE or IO::Async (which is a total misnomer as it is	81	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	82	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	83	like joining a cult: After you join, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	84	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	85	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.	86	module are I<also> forced to use the same event loop you use.
50		87
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	89	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	90	with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
54	your module uses one of those, every user of your module has to use it,	91	uses one of those, every user of your module has to use it, too. But if
55	too. But if your module uses AnyEvent, it works transparently with all	92	your module uses AnyEvent, it works transparently with all event models it
56	event models it supports (including stuff like POE and IO::Async, as long	93	supports (including stuff like IO::Async, as long as those use one of the
57	as those use one of the supported event loops. It is trivial to add new	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
58	event loops to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
59		96
60	In addition to being free of having to use I<the one and only true event	97	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	98	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enourmous amount of code and strict rules you have to	99	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	100	follow. AnyEvent, on the other hand, is lean and to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	101	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	102	technically possible.
66		103
		104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		105	of useful functionality, such as an asynchronous DNS resolver, 100%
		106	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		107	such as Windows) and lots of real-world knowledge and workarounds for
		108	platform bugs and differences.
		109
67	Of course, if you want lots of policy (this can arguably be somewhat	110	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	111	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	112	model, you should I<not> use this module.
70		113
71
72	=head1 DESCRIPTION	114	=head1 DESCRIPTION
73		115
74	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
75	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
76	users to use the same event loop (as only a single event loop can coexist	118	module users to use a specific event loop implementation (since more
77	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
78		120
79	The interface itself is vaguely similar, but not identical to the L<Event>	121	The interface itself is vaguely similar, but not identical to the L<Event>
80	module.	122	module.
81		123
82	During the first call of any watcher-creation method, the module tries	124	During the first call of any watcher-creation method, the module tries
83	to detect the currently loaded event loop by probing whether one of the	125	to detect the currently loaded event loop by probing whether one of the
84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
85	L<Event>, L<Glib>, L<Tk>. The first one found is used. If none are found,	127	L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
86	the module tries to load these modules in the stated order. The first one	128	found is used. If none are detected, the module tries to load the first
87	that can be successfully loaded will be used. If, after this, still none	129	four modules in the order given; but note that if L<EV> is not
88	could be found, AnyEvent will fall back to a pure-perl event loop, which	130	available, the pure-perl L<AnyEvent::Loop> should always work, so
89	is not very efficient, but should work everywhere.	131	the other two are not normally tried.
90		132
91	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
92	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
93	that model the default. For example:	135	that model the default. For example:
94		136
…		…
96	use AnyEvent;	138	use AnyEvent;
97		139
98	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
99		141
100	The I<likely> means that, if any module loads another event model and	142	The I<likely> means that, if any module loads another event model and
101	starts using it, all bets are off. Maybe you should tell their authors to	143	starts using it, all bets are off - this case should be very rare though,
102	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
103		146
104	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
105	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	148	other event modules you can load it explicitly and enjoy the high
106	explicitly.	149	availability of that event loop :)
107		150
108	=head1 WATCHERS	151	=head1 WATCHERS
109		152
110	AnyEvent has the central concept of a I<watcher>, which is an object that	153	AnyEvent has the central concept of a I<watcher>, which is an object that
111	stores relevant data for each kind of event you are waiting for, such as	154	stores relevant data for each kind of event you are waiting for, such as
112	the callback to call, the filehandle to watch, etc.	155	the callback to call, the file handle to watch, etc.
113		156
114	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
115	creating a watcher it will immediately "watch" for events and invoke the	158	creating a watcher it will immediately "watch" for events and invoke the
116	callback when the event occurs (of course, only when the event model	159	callback when the event occurs (of course, only when the event model
117	is in control).	160	is in control).
118		161
		162	Note that B<callbacks must not permanently change global variables>
		163	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		164	callbacks must not C<die> >>. The former is good programming practice in
		165	Perl and the latter stems from the fact that exception handling differs
		166	widely between event loops.
		167
119	To disable the watcher you have to destroy it (e.g. by setting the	168	To disable a watcher you have to destroy it (e.g. by setting the
120	variable you store it in to C<undef> or otherwise deleting all references	169	variable you store it in to C<undef> or otherwise deleting all references
121	to it).	170	to it).
122		171
123	All watchers are created by calling a method on the C<AnyEvent> class.	172	All watchers are created by calling a method on the C<AnyEvent> class.
124		173
125	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
126	example), or need to refer to their watcher object in other ways.	175	example), or need to refer to their watcher object in other ways.
127		176
128	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
129		178
130	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
131	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
132	undef $w;	181	undef $w;
133	});	182	});
134		183
135	Note that C<my $w; $w => combination. This is necessary because in Perl,	184	Note that C<my $w; $w => combination. This is necessary because in Perl,
136	my variables are only visible after the statement in which they are	185	my variables are only visible after the statement in which they are
137	declared.	186	declared.
138		187
139	=head2 IO WATCHERS	188	=head2 I/O WATCHERS
		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
140		195
141	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	196	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
142	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
143		198
144	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		200	for events (AnyEvent might or might not keep a reference to this file
		201	handle). Note that only file handles pointing to things for which
		202	non-blocking operation makes sense are allowed. This includes sockets,
		203	most character devices, pipes, fifos and so on, but not for example files
		204	or block devices.
		205
145	events. C<poll> must be a string that is either C<r> or C<w>, which	206	C<poll> must be a string that is either C<r> or C<w>, which creates a
146	creates a watcher waiting for "r"eadable or "w"ritable events,	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
147	respectively. C<cb> is the callback to invoke each time the file handle	209	C<cb> is the callback to invoke each time the file handle becomes ready.
148	becomes ready.
149		210
150	As long as the I/O watcher exists it will keep the file descriptor or a	211	Although the callback might get passed parameters, their value and
151	copy of it alive/open.	212	presence is undefined and you cannot rely on them. Portable AnyEvent
		213	callbacks cannot use arguments passed to I/O watcher callbacks.
152		214
		215	The I/O watcher might use the underlying file descriptor or a copy of it.
153	It is not allowed to close a file handle as long as any watcher is active	216	You must not close a file handle as long as any watcher is active on the
154	on the underlying file descriptor.	217	underlying file descriptor.
155		218
156	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
157	always use non-blocking calls when reading/writing from/to your file	220	always use non-blocking calls when reading/writing from/to your file
158	handles.	221	handles.
159		222
160	Example:
161
162	# wait for readability of STDIN, then read a line and disable the watcher	223	Example: wait for readability of STDIN, then read a line and disable the
		224	watcher.
		225
163	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	226	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
164	chomp (my $input = <STDIN>);	227	chomp (my $input = <STDIN>);
165	warn "read: $input\n";	228	warn "read: $input\n";
166	undef $w;	229	undef $w;
167	});	230	});
168		231
169	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
170		233
		234	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		235
		236	$w = AnyEvent->timer (
		237	after => <fractional_seconds>,
		238	interval => <fractional_seconds>,
		239	cb => <callback>,
		240	);
		241
171	You can create a time watcher by calling the C<< AnyEvent->timer >>	242	You can create a time watcher by calling the C<< AnyEvent->timer >>
172	method with the following mandatory arguments:	243	method with the following mandatory arguments:
173		244
174	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
175	supported) should the timer activate. C<cb> the callback to invoke in that	246	supported) the callback should be invoked. C<cb> is the callback to invoke
176	case.	247	in that case.
177		248
178	The timer callback will be invoked at most once: if you want a repeating	249	Although the callback might get passed parameters, their value and
179	timer you have to create a new watcher (this is a limitation by both Tk	250	presence is undefined and you cannot rely on them. Portable AnyEvent
180	and Glib).	251	callbacks cannot use arguments passed to time watcher callbacks.
181		252
182	Example:	253	The callback will normally be invoked only once. If you specify another
		254	parameter, C<interval>, as a strictly positive number (> 0), then the
		255	callback will be invoked regularly at that interval (in fractional
		256	seconds) after the first invocation. If C<interval> is specified with a
		257	false value, then it is treated as if it were not specified at all.
183		258
		259	The callback will be rescheduled before invoking the callback, but no
		260	attempt is made to avoid timer drift in most backends, so the interval is
		261	only approximate.
		262
184	# fire an event after 7.7 seconds	263	Example: fire an event after 7.7 seconds.
		264
185	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
186	warn "timeout\n";	266	warn "timeout\n";
187	});	267	});
188		268
189	# to cancel the timer:	269	# to cancel the timer:
190	undef $w;	270	undef $w;
191		271
192	Example 2:
193
194	# fire an event after 0.5 seconds, then roughly every second	272	Example 2: fire an event after 0.5 seconds, then roughly every second.
195	my $w;
196		273
197	my $cb = sub {
198	# cancel the old timer while creating a new one
199	$w = AnyEvent->timer (after => 1, cb => $cb);	274	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		275	warn "timeout\n";
200	};	276	};
201
202	# start the "loop" by creating the first watcher
203	$w = AnyEvent->timer (after => 0.5, cb => $cb);
204		277
205	=head3 TIMING ISSUES	278	=head3 TIMING ISSUES
206		279
207	There are two ways to handle timers: based on real time (relative, "fire	280	There are two ways to handle timers: based on real time (relative, "fire
208	in 10 seconds") and based on wallclock time (absolute, "fire at 12	281	in 10 seconds") and based on wallclock time (absolute, "fire at 12
209	o'clock").	282	o'clock").
210		283
211	While most event loops expect timers to specified in a relative way, they use	284	While most event loops expect timers to specified in a relative way, they
212	absolute time internally. This makes a difference when your clock "jumps",	285	use absolute time internally. This makes a difference when your clock
213	for example, when ntp decides to set your clock backwards from the wrong 2014-01-01 to	286	"jumps", for example, when ntp decides to set your clock backwards from
214	2008-01-01, a watcher that you created to fire "after" a second might actually take	287	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
215	six years to finally fire.	288	fire "after a second" might actually take six years to finally fire.
216		289
217	AnyEvent cannot compensate for this. The only event loop that is conscious	290	AnyEvent cannot compensate for this. The only event loop that is conscious
218	about these issues is L<EV>, which offers both relative (ev_timer) and	291	of these issues is L<EV>, which offers both relative (ev_timer, based
219	absolute (ev_periodic) timers.	292	on true relative time) and absolute (ev_periodic, based on wallclock time)
		293	timers.
220		294
221	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
222	AnyEvent API.	296	AnyEvent API.
223		297
		298	AnyEvent has two additional methods that return the "current time":
		299
		300	=over 4
		301
		302	=item AnyEvent->time
		303
		304	This returns the "current wallclock time" as a fractional number of
		305	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		306	return, and the result is guaranteed to be compatible with those).
		307
		308	It progresses independently of any event loop processing, i.e. each call
		309	will check the system clock, which usually gets updated frequently.
		310
		311	=item AnyEvent->now
		312
		313	This also returns the "current wallclock time", but unlike C<time>, above,
		314	this value might change only once per event loop iteration, depending on
		315	the event loop (most return the same time as C<time>, above). This is the
		316	time that AnyEvent's timers get scheduled against.
		317
		318	I<In almost all cases (in all cases if you don't care), this is the
		319	function to call when you want to know the current time.>
		320
		321	This function is also often faster then C<< AnyEvent->time >>, and
		322	thus the preferred method if you want some timestamp (for example,
		323	L<AnyEvent::Handle> uses this to update its activity timeouts).
		324
		325	The rest of this section is only of relevance if you try to be very exact
		326	with your timing; you can skip it without a bad conscience.
		327
		328	For a practical example of when these times differ, consider L<Event::Lib>
		329	and L<EV> and the following set-up:
		330
		331	The event loop is running and has just invoked one of your callbacks at
		332	time=500 (assume no other callbacks delay processing). In your callback,
		333	you wait a second by executing C<sleep 1> (blocking the process for a
		334	second) and then (at time=501) you create a relative timer that fires
		335	after three seconds.
		336
		337	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		338	both return C<501>, because that is the current time, and the timer will
		339	be scheduled to fire at time=504 (C<501> + C<3>).
		340
		341	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		342	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		343	last event processing phase started. With L<EV>, your timer gets scheduled
		344	to run at time=503 (C<500> + C<3>).
		345
		346	In one sense, L<Event::Lib> is more exact, as it uses the current time
		347	regardless of any delays introduced by event processing. However, most
		348	callbacks do not expect large delays in processing, so this causes a
		349	higher drift (and a lot more system calls to get the current time).
		350
		351	In another sense, L<EV> is more exact, as your timer will be scheduled at
		352	the same time, regardless of how long event processing actually took.
		353
		354	In either case, if you care (and in most cases, you don't), then you
		355	can get whatever behaviour you want with any event loop, by taking the
		356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		357	account.
		358
		359	=item AnyEvent->now_update
		360
		361	Some event loops (such as L<EV> or L<AnyEvent::Loop>) cache the current
		362	time for each loop iteration (see the discussion of L<< AnyEvent->now >>,
		363	above).
		364
		365	When a callback runs for a long time (or when the process sleeps), then
		366	this "current" time will differ substantially from the real time, which
		367	might affect timers and time-outs.
		368
		369	When this is the case, you can call this method, which will update the
		370	event loop's idea of "current time".
		371
		372	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		373	when mod_perl executes the script, then the event loop will have the wrong
		374	idea about the "current time" (being potentially far in the past, when the
		375	script ran the last time). In that case you should arrange a call to C<<
		376	AnyEvent->now_update >> each time the web server process wakes up again
		377	(e.g. at the start of your script, or in a handler).
		378
		379	Note that updating the time I<might> cause some events to be handled.
		380
		381	=back
		382
224	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
225		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		386
226	You can watch for signals using a signal watcher, C<signal> is the signal	387	You can watch for signals using a signal watcher, C<signal> is the signal
227	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	388	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
228	be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
229		390
		391	Although the callback might get passed parameters, their value and
		392	presence is undefined and you cannot rely on them. Portable AnyEvent
		393	callbacks cannot use arguments passed to signal watcher callbacks.
		394
230	Multiple signals occurances can be clumped together into one callback	395	Multiple signal occurrences can be clumped together into one callback
231	invocation, and callback invocation will be synchronous. synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
232	that it might take a while until the signal gets handled by the process,	397	that it might take a while until the signal gets handled by the process,
233	but it is guarenteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
234		399
235	The main advantage of using these watchers is that you can share a signal	400	The main advantage of using these watchers is that you can share a signal
236	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
237		403
238	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
239	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
240		407
241	Example: exit on SIGINT	408	Example: exit on SIGINT
242		409
243	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
244		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling)
		421	or "unsafe" (asynchronous) - the former might delay signal delivery
		422	indefinitely, the latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support
		432	attaching callbacks to signals in a generic way, which is a pity,
		433	as you cannot do race-free signal handling in perl, requiring
		434	C libraries for this. AnyEvent will try to do its best, which
		435	means in some cases, signals will be delayed. The maximum time
		436	a signal might be delayed is 10 seconds by default, but can
		437	be overriden via C<$ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY}> or
		438	C<$AnyEvent::MAX_SIGNAL_LATENCY> - see the Ö<ENVIRONMENT VARIABLES>
		439	section for details.
		440
		441	All these problems can be avoided by installing the optional
		442	L<Async::Interrupt> module, which works with most event loops. It will not
		443	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		444	(and not with L<POE> currently). For those, you just have to suffer the
		445	delays.
		446
245	=head2 CHILD PROCESS WATCHERS	447	=head2 CHILD PROCESS WATCHERS
246		448
		449	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		450
247	You can also watch on a child process exit and catch its exit status.	451	You can also watch for a child process exit and catch its exit status.
248		452
249	The child process is specified by the C<pid> argument (if set to C<0>, it	453	The child process is specified by the C<pid> argument (on some backends,
250	watches for any child process exit). The watcher will trigger as often	454	using C<0> watches for any child process exit, on others this will
251	as status change for the child are received. This works by installing a	455	croak). The watcher will be triggered only when the child process has
252	signal handler for C<SIGCHLD>. The callback will be called with the pid	456	finished and an exit status is available, not on any trace events
253	and exit status (as returned by waitpid).	457	(stopped/continued).
254		458
255	Example: wait for pid 1333	459	The callback will be called with the pid and exit status (as returned by
		460	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		461	callback arguments.
256		462
		463	This watcher type works by installing a signal handler for C<SIGCHLD>,
		464	and since it cannot be shared, nothing else should use SIGCHLD or reap
		465	random child processes (waiting for specific child processes, e.g. inside
		466	C<system>, is just fine).
		467
		468	There is a slight catch to child watchers, however: you usually start them
		469	I<after> the child process was created, and this means the process could
		470	have exited already (and no SIGCHLD will be sent anymore).
		471
		472	Not all event models handle this correctly (neither POE nor IO::Async do,
		473	see their AnyEvent::Impl manpages for details), but even for event models
		474	that I<do> handle this correctly, they usually need to be loaded before
		475	the process exits (i.e. before you fork in the first place). AnyEvent's
		476	pure perl event loop handles all cases correctly regardless of when you
		477	start the watcher.
		478
		479	This means you cannot create a child watcher as the very first
		480	thing in an AnyEvent program, you I<have> to create at least one
		481	watcher before you C<fork> the child (alternatively, you can call
		482	C<AnyEvent::detect>).
		483
		484	As most event loops do not support waiting for child events, they will be
		485	emulated by AnyEvent in most cases, in which case the latency and race
		486	problems mentioned in the description of signal watchers apply.
		487
		488	Example: fork a process and wait for it
		489
		490	my $done = AnyEvent->condvar;
		491
		492	my $pid = fork or exit 5;
		493
257	my $w = AnyEvent->child (	494	my $w = AnyEvent->child (
258	pid => 1333,	495	pid => $pid,
259	cb => sub {	496	cb => sub {
260	my ($pid, $status) = @_;	497	my ($pid, $status) = @_;
261	warn "pid $pid exited with status $status";	498	warn "pid $pid exited with status $status";
		499	$done->send;
262	},	500	},
263	);	501	);
		502
		503	# do something else, then wait for process exit
		504	$done->recv;
		505
		506	=head2 IDLE WATCHERS
		507
		508	$w = AnyEvent->idle (cb => <callback>);
		509
		510	This will repeatedly invoke the callback after the process becomes idle,
		511	until either the watcher is destroyed or new events have been detected.
		512
		513	Idle watchers are useful when there is a need to do something, but it
		514	is not so important (or wise) to do it instantly. The callback will be
		515	invoked only when there is "nothing better to do", which is usually
		516	defined as "all outstanding events have been handled and no new events
		517	have been detected". That means that idle watchers ideally get invoked
		518	when the event loop has just polled for new events but none have been
		519	detected. Instead of blocking to wait for more events, the idle watchers
		520	will be invoked.
		521
		522	Unfortunately, most event loops do not really support idle watchers (only
		523	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		524	will simply call the callback "from time to time".
		525
		526	Example: read lines from STDIN, but only process them when the
		527	program is otherwise idle:
		528
		529	my @lines; # read data
		530	my $idle_w;
		531	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		532	push @lines, scalar <STDIN>;
		533
		534	# start an idle watcher, if not already done
		535	$idle_w ||= AnyEvent->idle (cb => sub {
		536	# handle only one line, when there are lines left
		537	if (my $line = shift @lines) {
		538	print "handled when idle: $line";
		539	} else {
		540	# otherwise disable the idle watcher again
		541	undef $idle_w;
		542	}
		543	});
		544	});
264		545
265	=head2 CONDITION VARIABLES	546	=head2 CONDITION VARIABLES
266		547
		548	$cv = AnyEvent->condvar;
		549
		550	$cv->send (<list>);
		551	my @res = $cv->recv;
		552
		553	If you are familiar with some event loops you will know that all of them
		554	require you to run some blocking "loop", "run" or similar function that
		555	will actively watch for new events and call your callbacks.
		556
		557	AnyEvent is slightly different: it expects somebody else to run the event
		558	loop and will only block when necessary (usually when told by the user).
		559
		560	The tool to do that is called a "condition variable", so called because
		561	they represent a condition that must become true.
		562
		563	Now is probably a good time to look at the examples further below.
		564
267	Condition variables can be created by calling the C<< AnyEvent->condvar >>	565	Condition variables can be created by calling the C<< AnyEvent->condvar
268	method without any arguments.	566	>> method, usually without arguments. The only argument pair allowed is
		567	C<cb>, which specifies a callback to be called when the condition variable
		568	becomes true, with the condition variable as the first argument (but not
		569	the results).
269		570
270	A condition variable waits for a condition - precisely that the C<<	571	After creation, the condition variable is "false" until it becomes "true"
271	->broadcast >> method has been called.	572	by calling the C<send> method (or calling the condition variable as if it
		573	were a callback, read about the caveats in the description for the C<<
		574	->send >> method).
272		575
273	They are very useful to signal that a condition has been fulfilled, for	576	Since condition variables are the most complex part of the AnyEvent API, here are
		577	some different mental models of what they are - pick the ones you can connect to:
		578
		579	=over 4
		580
		581	=item * Condition variables are like callbacks - you can call them (and pass them instead
		582	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		583
		584	=item * Condition variables are signals - one side can emit or send them,
		585	the other side can wait for them, or install a handler that is called when
		586	the signal fires.
		587
		588	=item * Condition variables are like "Merge Points" - points in your program
		589	where you merge multiple independent results/control flows into one.
		590
		591	=item * Condition variables represent a transaction - functions that start
		592	some kind of transaction can return them, leaving the caller the choice
		593	between waiting in a blocking fashion, or setting a callback.
		594
		595	=item * Condition variables represent future values, or promises to deliver
		596	some result, long before the result is available.
		597
		598	=back
		599
		600	Condition variables are very useful to signal that something has finished,
274	example, if you write a module that does asynchronous http requests,	601	for example, if you write a module that does asynchronous http requests,
275	then a condition variable would be the ideal candidate to signal the	602	then a condition variable would be the ideal candidate to signal the
276	availability of results.	603	availability of results. The user can either act when the callback is
		604	called or can synchronously C<< ->recv >> for the results.
277		605
278	You can also use condition variables to block your main program until	606	You can also use them to simulate traditional event loops - for example,
279	an event occurs - for example, you could C<< ->wait >> in your main	607	you can block your main program until an event occurs - for example, you
280	program until the user clicks the Quit button in your app, which would C<<	608	could C<< ->recv >> in your main program until the user clicks the Quit
281	->broadcast >> the "quit" event.	609	button of your app, which would C<< ->send >> the "quit" event.
282		610
283	Note that condition variables recurse into the event loop - if you have	611	Note that condition variables recurse into the event loop - if you have
284	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	612	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
285	lose. Therefore, condition variables are good to export to your caller, but	613	lose. Therefore, condition variables are good to export to your caller, but
286	you should avoid making a blocking wait yourself, at least in callbacks,	614	you should avoid making a blocking wait yourself, at least in callbacks,
287	as this asks for trouble.	615	as this asks for trouble.
288		616
289	This object has two methods:	617	Condition variables are represented by hash refs in perl, and the keys
		618	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		619	easy (it is often useful to build your own transaction class on top of
		620	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		621	its C<new> method in your own C<new> method.
		622
		623	There are two "sides" to a condition variable - the "producer side" which
		624	eventually calls C<< -> send >>, and the "consumer side", which waits
		625	for the send to occur.
		626
		627	Example: wait for a timer.
		628
		629	# condition: "wait till the timer is fired"
		630	my $timer_fired = AnyEvent->condvar;
		631
		632	# create the timer - we could wait for, say
		633	# a handle becomign ready, or even an
		634	# AnyEvent::HTTP request to finish, but
		635	# in this case, we simply use a timer:
		636	my $w = AnyEvent->timer (
		637	after => 1,
		638	cb => sub { $timer_fired->send },
		639	);
		640
		641	# this "blocks" (while handling events) till the callback
		642	# calls ->send
		643	$timer_fired->recv;
		644
		645	Example: wait for a timer, but take advantage of the fact that condition
		646	variables are also callable directly.
		647
		648	my $done = AnyEvent->condvar;
		649	my $delay = AnyEvent->timer (after => 5, cb => $done);
		650	$done->recv;
		651
		652	Example: Imagine an API that returns a condvar and doesn't support
		653	callbacks. This is how you make a synchronous call, for example from
		654	the main program:
		655
		656	use AnyEvent::CouchDB;
		657
		658	...
		659
		660	my @info = $couchdb->info->recv;
		661
		662	And this is how you would just set a callback to be called whenever the
		663	results are available:
		664
		665	$couchdb->info->cb (sub {
		666	my @info = $_[0]->recv;
		667	});
		668
		669	=head3 METHODS FOR PRODUCERS
		670
		671	These methods should only be used by the producing side, i.e. the
		672	code/module that eventually sends the signal. Note that it is also
		673	the producer side which creates the condvar in most cases, but it isn't
		674	uncommon for the consumer to create it as well.
290		675
291	=over 4	676	=over 4
292		677
		678	=item $cv->send (...)
		679
		680	Flag the condition as ready - a running C<< ->recv >> and all further
		681	calls to C<recv> will (eventually) return after this method has been
		682	called. If nobody is waiting the send will be remembered.
		683
		684	If a callback has been set on the condition variable, it is called
		685	immediately from within send.
		686
		687	Any arguments passed to the C<send> call will be returned by all
		688	future C<< ->recv >> calls.
		689
		690	Condition variables are overloaded so one can call them directly (as if
		691	they were a code reference). Calling them directly is the same as calling
		692	C<send>.
		693
		694	=item $cv->croak ($error)
		695
		696	Similar to send, but causes all calls to C<< ->recv >> to invoke
		697	C<Carp::croak> with the given error message/object/scalar.
		698
		699	This can be used to signal any errors to the condition variable
		700	user/consumer. Doing it this way instead of calling C<croak> directly
		701	delays the error detection, but has the overwhelming advantage that it
		702	diagnoses the error at the place where the result is expected, and not
		703	deep in some event callback with no connection to the actual code causing
		704	the problem.
		705
		706	=item $cv->begin ([group callback])
		707
293	=item $cv->wait	708	=item $cv->end
294		709
295	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	710	These two methods can be used to combine many transactions/events into
296	called on c<$cv>, while servicing other watchers normally.	711	one. For example, a function that pings many hosts in parallel might want
		712	to use a condition variable for the whole process.
297		713
		714	Every call to C<< ->begin >> will increment a counter, and every call to
		715	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		716	>>, the (last) callback passed to C<begin> will be executed, passing the
		717	condvar as first argument. That callback is I<supposed> to call C<< ->send
		718	>>, but that is not required. If no group callback was set, C<send> will
		719	be called without any arguments.
		720
		721	You can think of C<< $cv->send >> giving you an OR condition (one call
		722	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		723	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		724
		725	Let's start with a simple example: you have two I/O watchers (for example,
		726	STDOUT and STDERR for a program), and you want to wait for both streams to
		727	close before activating a condvar:
		728
		729	my $cv = AnyEvent->condvar;
		730
		731	$cv->begin; # first watcher
		732	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		733	defined sysread $fh1, my $buf, 4096
		734	or $cv->end;
		735	});
		736
		737	$cv->begin; # second watcher
		738	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		739	defined sysread $fh2, my $buf, 4096
		740	or $cv->end;
		741	});
		742
		743	$cv->recv;
		744
		745	This works because for every event source (EOF on file handle), there is
		746	one call to C<begin>, so the condvar waits for all calls to C<end> before
		747	sending.
		748
		749	The ping example mentioned above is slightly more complicated, as the
		750	there are results to be passwd back, and the number of tasks that are
		751	begun can potentially be zero:
		752
		753	my $cv = AnyEvent->condvar;
		754
		755	my %result;
		756	$cv->begin (sub { shift->send (\%result) });
		757
		758	for my $host (@list_of_hosts) {
		759	$cv->begin;
		760	ping_host_then_call_callback $host, sub {
		761	$result{$host} = ...;
		762	$cv->end;
		763	};
		764	}
		765
		766	$cv->end;
		767
		768	This code fragment supposedly pings a number of hosts and calls
		769	C<send> after results for all then have have been gathered - in any
		770	order. To achieve this, the code issues a call to C<begin> when it starts
		771	each ping request and calls C<end> when it has received some result for
		772	it. Since C<begin> and C<end> only maintain a counter, the order in which
		773	results arrive is not relevant.
		774
		775	There is an additional bracketing call to C<begin> and C<end> outside the
		776	loop, which serves two important purposes: first, it sets the callback
		777	to be called once the counter reaches C<0>, and second, it ensures that
		778	C<send> is called even when C<no> hosts are being pinged (the loop
		779	doesn't execute once).
		780
		781	This is the general pattern when you "fan out" into multiple (but
		782	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
		783	the callback and ensure C<end> is called at least once, and then, for each
		784	subrequest you start, call C<begin> and for each subrequest you finish,
		785	call C<end>.
		786
		787	=back
		788
		789	=head3 METHODS FOR CONSUMERS
		790
		791	These methods should only be used by the consuming side, i.e. the
		792	code awaits the condition.
		793
		794	=over 4
		795
		796	=item $cv->recv
		797
		798	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
		799	>> methods have been called on C<$cv>, while servicing other watchers
		800	normally.
		801
298	You can only wait once on a condition - additional calls will return	802	You can only wait once on a condition - additional calls are valid but
299	immediately.	803	will return immediately.
		804
		805	If an error condition has been set by calling C<< ->croak >>, then this
		806	function will call C<croak>.
		807
		808	In list context, all parameters passed to C<send> will be returned,
		809	in scalar context only the first one will be returned.
		810
		811	Note that doing a blocking wait in a callback is not supported by any
		812	event loop, that is, recursive invocation of a blocking C<< ->recv
		813	>> is not allowed, and the C<recv> call will C<croak> if such a
		814	condition is detected. This condition can be slightly loosened by using
		815	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		816	any thread that doesn't run the event loop itself.
300		817
301	Not all event models support a blocking wait - some die in that case	818	Not all event models support a blocking wait - some die in that case
302	(programs might want to do that to stay interactive), so I<if you are	819	(programs might want to do that to stay interactive), so I<if you are
303	using this from a module, never require a blocking wait>, but let the	820	using this from a module, never require a blocking wait>. Instead, let the
304	caller decide whether the call will block or not (for example, by coupling	821	caller decide whether the call will block or not (for example, by coupling
305	condition variables with some kind of request results and supporting	822	condition variables with some kind of request results and supporting
306	callbacks so the caller knows that getting the result will not block,	823	callbacks so the caller knows that getting the result will not block,
307	while still suppporting blocking waits if the caller so desires).	824	while still supporting blocking waits if the caller so desires).
308		825
309	Another reason I<never> to C<< ->wait >> in a module is that you cannot	826	You can ensure that C<< ->recv >> never blocks by setting a callback and
310	sensibly have two C<< ->wait >>'s in parallel, as that would require	827	only calling C<< ->recv >> from within that callback (or at a later
311	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	828	time). This will work even when the event loop does not support blocking
312	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	829	waits otherwise.
313	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
314	from different coroutines, however).
315		830
316	=item $cv->broadcast	831	=item $bool = $cv->ready
317		832
318	Flag the condition as ready - a running C<< ->wait >> and all further	833	Returns true when the condition is "true", i.e. whether C<send> or
319	calls to C<wait> will (eventually) return after this method has been	834	C<croak> have been called.
320	called. If nobody is waiting the broadcast will be remembered..	835
		836	=item $cb = $cv->cb ($cb->($cv))
		837
		838	This is a mutator function that returns the callback set and optionally
		839	replaces it before doing so.
		840
		841	The callback will be called when the condition becomes "true", i.e. when
		842	C<send> or C<croak> are called, with the only argument being the
		843	condition variable itself. If the condition is already true, the
		844	callback is called immediately when it is set. Calling C<recv> inside
		845	the callback or at any later time is guaranteed not to block.
321		846
322	=back	847	=back
323		848
324	Example:	849	=head1 SUPPORTED EVENT LOOPS/BACKENDS
325		850
326	# wait till the result is ready	851	The available backend classes are (every class has its own manpage):
327	my $result_ready = AnyEvent->condvar;
328		852
329	# do something such as adding a timer	853	=over 4
330	# or socket watcher the calls $result_ready->broadcast
331	# when the "result" is ready.
332	# in this case, we simply use a timer:
333	my $w = AnyEvent->timer (
334	after => 1,
335	cb => sub { $result_ready->broadcast },
336	);
337		854
338	# this "blocks" (while handling events) till the watcher	855	=item Backends that are autoprobed when no other event loop can be found.
339	# calls broadcast	856
340	$result_ready->wait;	857	EV is the preferred backend when no other event loop seems to be in
		858	use. If EV is not installed, then AnyEvent will fall back to its own
		859	pure-perl implementation, which is available everywhere as it comes with
		860	AnyEvent itself.
		861
		862	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		863	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
		864
		865	=item Backends that are transparently being picked up when they are used.
		866
		867	These will be used if they are already loaded when the first watcher
		868	is created, in which case it is assumed that the application is using
		869	them. This means that AnyEvent will automatically pick the right backend
		870	when the main program loads an event module before anything starts to
		871	create watchers. Nothing special needs to be done by the main program.
		872
		873	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		874	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		875	AnyEvent::Impl::Tk based on Tk, very broken.
		876	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		877	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		878	AnyEvent::Impl::Irssi used when running within irssi.
		879	AnyEvent::Impl::IOAsync based on IO::Async.
		880	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		881	AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding).
		882
		883	=item Backends with special needs.
		884
		885	Qt requires the Qt::Application to be instantiated first, but will
		886	otherwise be picked up automatically. As long as the main program
		887	instantiates the application before any AnyEvent watchers are created,
		888	everything should just work.
		889
		890	AnyEvent::Impl::Qt based on Qt.
		891
		892	=item Event loops that are indirectly supported via other backends.
		893
		894	Some event loops can be supported via other modules:
		895
		896	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		897
		898	B<WxWidgets> has no support for watching file handles. However, you can
		899	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		900	polls 20 times per second, which was considered to be too horrible to even
		901	consider for AnyEvent.
		902
		903	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		904	backend, so it can be supported through POE.
		905
		906	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		907	load L<POE> when detecting them, in the hope that POE will pick them up,
		908	in which case everything will be automatic.
		909
		910	=back
341		911
342	=head1 GLOBAL VARIABLES AND FUNCTIONS	912	=head1 GLOBAL VARIABLES AND FUNCTIONS
343		913
		914	These are not normally required to use AnyEvent, but can be useful to
		915	write AnyEvent extension modules.
		916
344	=over 4	917	=over 4
345		918
346	=item $AnyEvent::MODEL	919	=item $AnyEvent::MODEL
347		920
348	Contains C<undef> until the first watcher is being created. Then it	921	Contains C<undef> until the first watcher is being created, before the
		922	backend has been autodetected.
		923
349	contains the event model that is being used, which is the name of the	924	Afterwards it contains the event model that is being used, which is the
350	Perl class implementing the model. This class is usually one of the	925	name of the Perl class implementing the model. This class is usually one
351	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	926	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
352	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	927	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
353		928	will be C<urxvt::anyevent>).
354	The known classes so far are:
355
356	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
357	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
358	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
359	AnyEvent::Impl::Event based on Event, second best choice.
360	AnyEvent::Impl::Glib based on Glib, third-best choice.
361	AnyEvent::Impl::Tk based on Tk, very bad choice.
362	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
363	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
364	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
365		929
366	=item AnyEvent::detect	930	=item AnyEvent::detect
367		931
368	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	932	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
369	if necessary. You should only call this function right before you would	933	if necessary. You should only call this function right before you would
370	have created an AnyEvent watcher anyway, that is, as late as possible at	934	have created an AnyEvent watcher anyway, that is, as late as possible at
371	runtime.	935	runtime, and not e.g. during initialisation of your module.
		936
		937	The effect of calling this function is as if a watcher had been created
		938	(specifically, actions that happen "when the first watcher is created"
		939	happen when calling detetc as well).
		940
		941	If you need to do some initialisation before AnyEvent watchers are
		942	created, use C<post_detect>.
		943
		944	=item $guard = AnyEvent::post_detect { BLOCK }
		945
		946	Arranges for the code block to be executed as soon as the event model is
		947	autodetected (or immediately if that has already happened).
		948
		949	The block will be executed I<after> the actual backend has been detected
		950	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		951	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		952	other initialisations - see the sources of L<AnyEvent::Strict> or
		953	L<AnyEvent::AIO> to see how this is used.
		954
		955	The most common usage is to create some global watchers, without forcing
		956	event module detection too early, for example, L<AnyEvent::AIO> creates
		957	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		958	avoid autodetecting the event module at load time.
		959
		960	If called in scalar or list context, then it creates and returns an object
		961	that automatically removes the callback again when it is destroyed (or
		962	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
		963	a case where this is useful.
		964
		965	Example: Create a watcher for the IO::AIO module and store it in
		966	C<$WATCHER>, but do so only do so after the event loop is initialised.
		967
		968	our WATCHER;
		969
		970	my $guard = AnyEvent::post_detect {
		971	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		972	};
		973
		974	# the ||= is important in case post_detect immediately runs the block,
		975	# as to not clobber the newly-created watcher. assigning both watcher and
		976	# post_detect guard to the same variable has the advantage of users being
		977	# able to just C<undef $WATCHER> if the watcher causes them grief.
		978
		979	$WATCHER ||= $guard;
		980
		981	=item @AnyEvent::post_detect
		982
		983	If there are any code references in this array (you can C<push> to it
		984	before or after loading AnyEvent), then they will be called directly
		985	after the event loop has been chosen.
		986
		987	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		988	if it is defined then the event loop has already been detected, and the
		989	array will be ignored.
		990
		991	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		992	it, as it takes care of these details.
		993
		994	This variable is mainly useful for modules that can do something useful
		995	when AnyEvent is used and thus want to know when it is initialised, but do
		996	not need to even load it by default. This array provides the means to hook
		997	into AnyEvent passively, without loading it.
		998
		999	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1000	together, you could put this into Coro (this is the actual code used by
		1001	Coro to accomplish this):
		1002
		1003	if (defined $AnyEvent::MODEL) {
		1004	# AnyEvent already initialised, so load Coro::AnyEvent
		1005	require Coro::AnyEvent;
		1006	} else {
		1007	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1008	# as soon as it is
		1009	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1010	}
		1011
		1012	=item AnyEvent::postpone { BLOCK }
		1013
		1014	Arranges for the block to be executed as soon as possible, but not before
		1015	the call itself returns. In practise, the block will be executed just
		1016	before the event loop polls for new events, or shortly afterwards.
		1017
		1018	This function never returns anything (to make the C<return postpone { ...
		1019	}> idiom more useful.
		1020
		1021	To understand the usefulness of this function, consider a function that
		1022	asynchronously does something for you and returns some transaction
		1023	object or guard to let you cancel the operation. For example,
		1024	C<AnyEvent::Socket::tcp_connect>:
		1025
		1026	# start a conenction attempt unless one is active
		1027	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1028	delete $self->{connect_guard};
		1029	...
		1030	};
		1031
		1032	Imagine that this function could instantly call the callback, for
		1033	example, because it detects an obvious error such as a negative port
		1034	number. Invoking the callback before the function returns causes problems
		1035	however: the callback will be called and will try to delete the guard
		1036	object. But since the function hasn't returned yet, there is nothing to
		1037	delete. When the function eventually returns it will assign the guard
		1038	object to C<< $self->{connect_guard} >>, where it will likely never be
		1039	deleted, so the program thinks it is still trying to connect.
		1040
		1041	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1042	callback directly on error:
		1043
		1044	$cb->(undef), return # signal error to callback, BAD!
		1045	if $some_error_condition;
		1046
		1047	It should use C<postpone>:
		1048
		1049	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1050	if $some_error_condition;
		1051
		1052	=item AnyEvent::log $level, $msg[, @args]
		1053
		1054	Log the given C<$msg> at the given C<$level>.
		1055
		1056	If L<AnyEvent::Log> is not loaded then this function makes a simple test
		1057	to see whether the message will be logged. If the test succeeds it will
		1058	load AnyEvent::Log and call C<AnyEvent::Log::log> - consequently, look at
		1059	the L<AnyEvent::Log> documentation for details.
		1060
		1061	If the test fails it will simply return. Right now this happens when a
		1062	numerical loglevel is used and it is larger than the level specified via
		1063	C<$ENV{PERL_ANYEVENT_VERBOSE}>.
		1064
		1065	If you want to sprinkle loads of logging calls around your code, consider
		1066	creating a logger callback with the C<AnyEvent::Log::logger> function,
		1067	which can reduce typing, codesize and can reduce the logging overhead
		1068	enourmously.
372		1069
373	=back	1070	=back
374		1071
375	=head1 WHAT TO DO IN A MODULE	1072	=head1 WHAT TO DO IN A MODULE
376		1073
…		…
380	Be careful when you create watchers in the module body - AnyEvent will	1077	Be careful when you create watchers in the module body - AnyEvent will
381	decide which event module to use as soon as the first method is called, so	1078	decide which event module to use as soon as the first method is called, so
382	by calling AnyEvent in your module body you force the user of your module	1079	by calling AnyEvent in your module body you force the user of your module
383	to load the event module first.	1080	to load the event module first.
384		1081
385	Never call C<< ->wait >> on a condition variable unless you I<know> that	1082	Never call C<< ->recv >> on a condition variable unless you I<know> that
386	the C<< ->broadcast >> method has been called on it already. This is	1083	the C<< ->send >> method has been called on it already. This is
387	because it will stall the whole program, and the whole point of using	1084	because it will stall the whole program, and the whole point of using
388	events is to stay interactive.	1085	events is to stay interactive.
389		1086
390	It is fine, however, to call C<< ->wait >> when the user of your module	1087	It is fine, however, to call C<< ->recv >> when the user of your module
391	requests it (i.e. if you create a http request object ad have a method	1088	requests it (i.e. if you create a http request object ad have a method
392	called C<results> that returns the results, it should call C<< ->wait >>	1089	called C<results> that returns the results, it may call C<< ->recv >>
393	freely, as the user of your module knows what she is doing. always).	1090	freely, as the user of your module knows what she is doing. Always).
394		1091
395	=head1 WHAT TO DO IN THE MAIN PROGRAM	1092	=head1 WHAT TO DO IN THE MAIN PROGRAM
396		1093
397	There will always be a single main program - the only place that should	1094	There will always be a single main program - the only place that should
398	dictate which event model to use.	1095	dictate which event model to use.
399		1096
400	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1097	If the program is not event-based, it need not do anything special, even
401	do anything special (it does not need to be event-based) and let AnyEvent	1098	when it depends on a module that uses an AnyEvent. If the program itself
402	decide which implementation to chose if some module relies on it.	1099	uses AnyEvent, but does not care which event loop is used, all it needs
		1100	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1101	available loop implementation.
403		1102
404	If the main program relies on a specific event model. For example, in	1103	If the main program relies on a specific event model - for example, in
405	Gtk2 programs you have to rely on the Glib module. You should load the	1104	Gtk2 programs you have to rely on the Glib module - you should load the
406	event module before loading AnyEvent or any module that uses it: generally	1105	event module before loading AnyEvent or any module that uses it: generally
407	speaking, you should load it as early as possible. The reason is that	1106	speaking, you should load it as early as possible. The reason is that
408	modules might create watchers when they are loaded, and AnyEvent will	1107	modules might create watchers when they are loaded, and AnyEvent will
409	decide on the event model to use as soon as it creates watchers, and it	1108	decide on the event model to use as soon as it creates watchers, and it
410	might chose the wrong one unless you load the correct one yourself.	1109	might choose the wrong one unless you load the correct one yourself.
411		1110
412	You can chose to use a rather inefficient pure-perl implementation by	1111	You can chose to use a pure-perl implementation by loading the
413	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	1112	C<AnyEvent::Loop> module, which gives you similar behaviour
414	behaviour everywhere, but letting AnyEvent chose is generally better.	1113	everywhere, but letting AnyEvent chose the model is generally better.
		1114
		1115	=head2 MAINLOOP EMULATION
		1116
		1117	Sometimes (often for short test scripts, or even standalone programs who
		1118	only want to use AnyEvent), you do not want to run a specific event loop.
		1119
		1120	In that case, you can use a condition variable like this:
		1121
		1122	AnyEvent->condvar->recv;
		1123
		1124	This has the effect of entering the event loop and looping forever.
		1125
		1126	Note that usually your program has some exit condition, in which case
		1127	it is better to use the "traditional" approach of storing a condition
		1128	variable somewhere, waiting for it, and sending it when the program should
		1129	exit cleanly.
		1130
		1131
		1132	=head1 OTHER MODULES
		1133
		1134	The following is a non-exhaustive list of additional modules that use
		1135	AnyEvent as a client and can therefore be mixed easily with other
		1136	AnyEvent modules and other event loops in the same program. Some of the
		1137	modules come as part of AnyEvent, the others are available via CPAN (see
		1138	L<http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for
		1139	a longer non-exhaustive list), and the list is heavily biased towards
		1140	modules of the AnyEvent author himself :)
		1141
		1142	=over 4
		1143
		1144	=item L<AnyEvent::Util>
		1145
		1146	Contains various utility functions that replace often-used blocking
		1147	functions such as C<inet_aton> with event/callback-based versions.
		1148
		1149	=item L<AnyEvent::Socket>
		1150
		1151	Provides various utility functions for (internet protocol) sockets,
		1152	addresses and name resolution. Also functions to create non-blocking tcp
		1153	connections or tcp servers, with IPv6 and SRV record support and more.
		1154
		1155	=item L<AnyEvent::Handle>
		1156
		1157	Provide read and write buffers, manages watchers for reads and writes,
		1158	supports raw and formatted I/O, I/O queued and fully transparent and
		1159	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
		1160
		1161	=item L<AnyEvent::DNS>
		1162
		1163	Provides rich asynchronous DNS resolver capabilities.
		1164
		1165	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1166
		1167	Implement event-based interfaces to the protocols of the same name (for
		1168	the curious, IGS is the International Go Server and FCP is the Freenet
		1169	Client Protocol).
		1170
		1171	=item L<AnyEvent::AIO>
		1172
		1173	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1174	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1175	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1176	file I/O, and much more.
		1177
		1178	=item L<AnyEvent::Filesys::Notify>
		1179
		1180	AnyEvent is good for non-blocking stuff, but it can't detect file or
		1181	path changes (e.g. "watch this directory for new files", "watch this
		1182	file for changes"). The L<AnyEvent::Filesys::Notify> module promises to
		1183	do just that in a portbale fashion, supporting inotify on GNU/Linux and
		1184	some weird, without doubt broken, stuff on OS X to monitor files. It can
		1185	fall back to blocking scans at regular intervals transparently on other
		1186	platforms, so it's about as portable as it gets.
		1187
		1188	(I haven't used it myself, but I haven't heard anybody complaining about
		1189	it yet).
		1190
		1191	=item L<AnyEvent::DBI>
		1192
		1193	Executes L<DBI> requests asynchronously in a proxy process for you,
		1194	notifying you in an event-based way when the operation is finished.
		1195
		1196	=item L<AnyEvent::HTTPD>
		1197
		1198	A simple embedded webserver.
		1199
		1200	=item L<AnyEvent::FastPing>
		1201
		1202	The fastest ping in the west.
		1203
		1204	=item L<Coro>
		1205
		1206	Has special support for AnyEvent via L<Coro::AnyEvent>, which allows you
		1207	to simply invert the flow control - don't call us, we will call you:
		1208
		1209	async {
		1210	Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
		1211	print "5 seconds later!\n";
		1212
		1213	Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
		1214	my $line = <STDIN>; # works for ttys
		1215
		1216	AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
		1217	my ($body, $hdr) = Coro::rouse_wait;
		1218	};
		1219
		1220	=back
415		1221
416	=cut	1222	=cut
417		1223
418	package AnyEvent;	1224	package AnyEvent;
419		1225
420	no warnings;	1226	# basically a tuned-down version of common::sense
421	use strict;	1227	sub common_sense {
		1228	# from common:.sense 3.4
		1229	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1230	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1231	$^H |= 0x00000600;
		1232	}
422		1233
		1234	BEGIN { AnyEvent::common_sense }
		1235
423	use Carp;	1236	use Carp ();
424		1237
425	our $VERSION = '3.12';	1238	our $VERSION = '6.02';
426	our $MODEL;	1239	our $MODEL;
427
428	our $AUTOLOAD;
429	our @ISA;	1240	our @ISA;
430
431	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
432
433	our @REGISTRY;	1241	our @REGISTRY;
		1242	our $VERBOSE;
		1243	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		1244	our $MAX_SIGNAL_LATENCY = $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} || 10; # executes after the BEGIN block below (tainting!)
434		1245
		1246	BEGIN {
		1247	require "AnyEvent/constants.pl";
		1248
		1249	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1250
		1251	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1252	if ${^TAINT};
		1253
		1254	$ENV{"PERL_ANYEVENT_$_"} = $ENV{"AE_$_"}
		1255	for grep s/^AE_// && !exists $ENV{"PERL_ANYEVENT_$_"}, keys %ENV;
		1256
		1257	@ENV{grep /^PERL_ANYEVENT_/, keys %ENV} = ()
		1258	if ${^TAINT};
		1259
		1260	# $ENV{PERL_ANYEVENT_xxx} now valid
		1261
		1262	$VERBOSE = length $ENV{PERL_ANYEVENT_VERBOSE} ? $ENV{PERL_ANYEVENT_VERBOSE}*1 : 4;
		1263
		1264	my $idx;
		1265	$PROTOCOL{$_} = ++$idx
		1266	for reverse split /\s*,\s*/,
		1267	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		1268	}
		1269
		1270	our @post_detect;
		1271
		1272	sub post_detect(&) {
		1273	my ($cb) = @_;
		1274
		1275	push @post_detect, $cb;
		1276
		1277	defined wantarray
		1278	? bless \$cb, "AnyEvent::Util::postdetect"
		1279	: ()
		1280	}
		1281
		1282	sub AnyEvent::Util::postdetect::DESTROY {
		1283	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1284	}
		1285
		1286	our $POSTPONE_W;
		1287	our @POSTPONE;
		1288
		1289	sub _postpone_exec {
		1290	undef $POSTPONE_W;
		1291
		1292	&{ shift @POSTPONE }
		1293	while @POSTPONE;
		1294	}
		1295
		1296	sub postpone(&) {
		1297	push @POSTPONE, shift;
		1298
		1299	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1300
		1301	()
		1302	}
		1303
		1304	sub log($$;@) {
		1305	# only load the big bloated module when we actually are about to log something
		1306	if ($_[0] <= ($VERBOSE || 1)) { # also catches non-numeric levels(!) and fatal
		1307	local ($!, $@);
		1308	require AnyEvent::Log; # among other things, sets $VERBOSE to 9
		1309	# AnyEvent::Log overwrites this function
		1310	goto &log;
		1311	}
		1312
		1313	0 # not logged
		1314	}
		1315
		1316	sub logger($;$) {
		1317	package AnyEvent::Log;
		1318
		1319	my ($level, $renabled) = @_;
		1320
		1321	$$renabled = $level <= $VERBOSE;
		1322
		1323	my $pkg = (caller)[0];
		1324
		1325	my $logger = [$pkg, $level, $renabled];
		1326
		1327	our %LOGGER;
		1328	$LOGGER{$logger+0} = $logger;
		1329
		1330	return unless defined wantarray;
		1331
		1332	require AnyEvent::Util;
		1333	my $guard = AnyEvent::Util::guard (sub {
		1334	# "clean up"
		1335	delete $LOGGER{$logger+0};
		1336	});
		1337
		1338	sub {
		1339	return 0 unless $$renabled;
		1340
		1341	$guard if 0; # keep guard alive, but don't cause runtime overhead
		1342	require AnyEvent::Log unless $AnyEvent::Log::VERSION;
		1343	package AnyEvent::Log;
		1344	_log ($logger->[0], $level, @_) # logger->[0] has been converted at load time
		1345	}
		1346	}
		1347
		1348	if (length $ENV{PERL_ANYEVENT_LOG}) {
		1349	require AnyEvent::Log; # AnyEvent::Log does the thing for us
		1350	}
		1351
435	my @models = (	1352	our @models = (
436	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
437	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
438	[EV:: => AnyEvent::Impl::EV::],	1353	[EV:: => AnyEvent::Impl::EV::],
		1354	[AnyEvent::Loop:: => AnyEvent::Impl::Perl::],
		1355	# everything below here will not (normally) be autoprobed
		1356	# as the pure perl backend should work everywhere
		1357	# and is usually faster
		1358	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package, so msut be near the top
439	[Event:: => AnyEvent::Impl::Event::],	1359	[Event:: => AnyEvent::Impl::Event::], # slow, stable
440	[Glib:: => AnyEvent::Impl::Glib::],	1360	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1361	# everything below here should not be autoloaded
		1362	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1363	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1364	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1365	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
441	[Tk:: => AnyEvent::Impl::Tk::],	1366	[Wx:: => AnyEvent::Impl::POE::],
442	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1367	[Prima:: => AnyEvent::Impl::POE::],
		1368	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1369	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1370	[FLTK:: => AnyEvent::Impl::FLTK::],
443	);	1371	);
444	my @models_detect = (
445	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
446	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
447	);
448		1372
449	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	1373	our @isa_hook;
		1374
		1375	sub _isa_set {
		1376	my @pkg = ("AnyEvent", (map $_->[0], grep defined, @isa_hook), $MODEL);
		1377
		1378	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1379	for 1 .. $#pkg;
		1380
		1381	grep $_ && $_->[1], @isa_hook
		1382	and AE::_reset ();
		1383	}
		1384
		1385	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1386	sub _isa_hook($$;$) {
		1387	my ($i, $pkg, $reset_ae) = @_;
		1388
		1389	$isa_hook[$i] = $pkg ? [$pkg, $reset_ae] : undef;
		1390
		1391	_isa_set;
		1392	}
		1393
		1394	# all autoloaded methods reserve the complete glob, not just the method slot.
		1395	# due to bugs in perls method cache implementation.
		1396	our @methods = qw(io timer time now now_update signal child idle condvar);
450		1397
451	sub detect() {	1398	sub detect() {
		1399	return $MODEL if $MODEL; # some programs keep references to detect
		1400
		1401	# IO::Async::Loop::AnyEvent is extremely evil, refuse to work with it
		1402	# the author knows about the problems and what it does to AnyEvent as a whole
		1403	# (and the ability of others to use AnyEvent), but simply wants to abuse AnyEvent
		1404	# anyway.
		1405	AnyEvent::log fatal => "AnyEvent: IO::Async::Loop::AnyEvent detected - this module is broken by design,\n"
		1406	. "abuses internals and breaks AnyEvent, will not continue."
		1407	if exists $INC{"IO/Async/Loop/AnyEvent.pm"};
		1408
		1409	local $!; # for good measure
		1410	local $SIG{__DIE__}; # we use eval
		1411
		1412	# free some memory
		1413	*detect = sub () { $MODEL };
		1414	# undef &func doesn't correctly update the method cache. grmbl.
		1415	# so we delete the whole glob. grmbl.
		1416	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1417	# a glob with an active sub. hrm. i hope it works, but perl is
		1418	# usually buggy in this department. sigh.
		1419	delete @{"AnyEvent::"}{@methods};
		1420	undef @methods;
		1421
		1422	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1423	my $model = $1;
		1424	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1425	if (eval "require $model") {
		1426	AnyEvent::log 7 => "loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.";
		1427	$MODEL = $model;
		1428	} else {
		1429	AnyEvent::log 4 => "unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
		1430	}
		1431	}
		1432
		1433	# check for already loaded models
452	unless ($MODEL) {	1434	unless ($MODEL) {
453	no strict 'refs';	1435	for (@REGISTRY, @models) {
454		1436	my ($package, $model) = @$_;
455	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1437	if (${"$package\::VERSION"} > 0) {
456	my $model = "AnyEvent::Impl::$1";
457	if (eval "require $model") {	1438	if (eval "require $model") {
		1439	AnyEvent::log 7 => "autodetected model '$model', using it.";
458	$MODEL = $model;	1440	$MODEL = $model;
459	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1441	last;
		1442	}
460	}	1443	}
461	}	1444	}
462		1445
463	# check for already loaded models
464	unless ($MODEL) {	1446	unless ($MODEL) {
		1447	# try to autoload a model
465	for (@REGISTRY, @models, @models_detect) {	1448	for (@REGISTRY, @models) {
466	my ($package, $model) = @$_;	1449	my ($package, $model) = @$_;
		1450	if (
		1451	eval "require $package"
467	if (${"$package\::VERSION"} > 0) {	1452	and ${"$package\::VERSION"} > 0
468	if (eval "require $model") {	1453	and eval "require $model"
		1454	) {
		1455	AnyEvent::log 7 => "autoloaded model '$model', using it.";
469	$MODEL = $model;	1456	$MODEL = $model;
470	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
471	last;	1457	last;
472	}
473	}	1458	}
474	}	1459	}
475		1460
476	unless ($MODEL) {	1461	$MODEL
477	# try to load a model	1462	or AnyEvent::log fatal => "AnyEvent: backend autodetection failed - did you properly install AnyEvent?";
		1463	}
		1464	}
478		1465
479	for (@REGISTRY, @models) {	1466	# free memory only needed for probing
480	my ($package, $model) = @$_;	1467	undef @models;
481	if (eval "require $package"	1468	undef @REGISTRY;
482	and ${"$package\::VERSION"} > 0	1469
483	and eval "require $model") {	1470	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
484	$MODEL = $model;	1471
485	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1472	# now nuke some methods that are overridden by the backend.
		1473	# SUPER usage is not allowed in these.
		1474	for (qw(time signal child idle)) {
		1475	undef &{"AnyEvent::Base::$_"}
		1476	if defined &{"$MODEL\::$_"};
		1477	}
		1478
		1479	_isa_set;
		1480
		1481	# we're officially open!
		1482
		1483	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1484	require AnyEvent::Strict;
		1485	}
		1486
		1487	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1488	require AnyEvent::Debug;
		1489	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1490	}
		1491
		1492	if (length $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1493	require AnyEvent::Socket;
		1494	require AnyEvent::Debug;
		1495
		1496	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1497	$shell =~ s/\$\$/$$/g;
		1498
		1499	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1500	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1501	}
		1502
		1503	# now the anyevent environment is set up as the user told us to, so
		1504	# call the actual user code - post detects
		1505
		1506	(shift @post_detect)->() while @post_detect;
		1507	undef @post_detect;
		1508
		1509	*post_detect = sub(&) {
		1510	shift->();
		1511
		1512	undef
		1513	};
		1514
		1515	$MODEL
		1516	}
		1517
		1518	for my $name (@methods) {
		1519	*$name = sub {
		1520	detect;
		1521	# we use goto because
		1522	# a) it makes the thunk more transparent
		1523	# b) it allows us to delete the thunk later
		1524	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
		1525	};
		1526	}
		1527
		1528	# utility function to dup a filehandle. this is used by many backends
		1529	# to support binding more than one watcher per filehandle (they usually
		1530	# allow only one watcher per fd, so we dup it to get a different one).
		1531	sub _dupfh($$;$$) {
		1532	my ($poll, $fh, $r, $w) = @_;
		1533
		1534	# cygwin requires the fh mode to be matching, unix doesn't
		1535	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1536
		1537	open my $fh2, $mode, $fh
		1538	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1539
		1540	# we assume CLOEXEC is already set by perl in all important cases
		1541
		1542	($fh2, $rw)
		1543	}
		1544
		1545	=head1 SIMPLIFIED AE API
		1546
		1547	Starting with version 5.0, AnyEvent officially supports a second, much
		1548	simpler, API that is designed to reduce the calling, typing and memory
		1549	overhead by using function call syntax and a fixed number of parameters.
		1550
		1551	See the L<AE> manpage for details.
		1552
		1553	=cut
		1554
		1555	package AE;
		1556
		1557	our $VERSION = $AnyEvent::VERSION;
		1558
		1559	sub _reset() {
		1560	eval q{
		1561	# fall back to the main API by default - backends and AnyEvent::Base
		1562	# implementations can overwrite these.
		1563
		1564	sub io($$$) {
		1565	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1566	}
		1567
		1568	sub timer($$$) {
		1569	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1570	}
		1571
		1572	sub signal($$) {
		1573	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1574	}
		1575
		1576	sub child($$) {
		1577	AnyEvent->child (pid => $_[0], cb => $_[1])
		1578	}
		1579
		1580	sub idle($) {
		1581	AnyEvent->idle (cb => $_[0]);
		1582	}
		1583
		1584	sub cv(;&) {
		1585	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1586	}
		1587
		1588	sub now() {
		1589	AnyEvent->now
		1590	}
		1591
		1592	sub now_update() {
		1593	AnyEvent->now_update
		1594	}
		1595
		1596	sub time() {
		1597	AnyEvent->time
		1598	}
		1599
		1600	*postpone = \&AnyEvent::postpone;
		1601	*log = \&AnyEvent::log;
		1602	};
		1603	die if $@;
		1604	}
		1605
		1606	BEGIN { _reset }
		1607
		1608	package AnyEvent::Base;
		1609
		1610	# default implementations for many methods
		1611
		1612	sub time {
		1613	eval q{ # poor man's autoloading {}
		1614	# probe for availability of Time::HiRes
		1615	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1616	*time = sub { Time::HiRes::time () };
		1617	*AE::time = \& Time::HiRes::time ;
		1618	*now = \&time;
		1619	AnyEvent::log 8 => "AnyEvent: using Time::HiRes for sub-second timing accuracy.";
		1620	# if (eval "use POSIX (); (POSIX::times())...
		1621	} else {
		1622	*time = sub { CORE::time };
		1623	*AE::time = sub (){ CORE::time };
		1624	*now = \&time;
		1625	AnyEvent::log 3 => "using built-in time(), WARNING, no sub-second resolution!";
		1626	}
		1627	};
		1628	die if $@;
		1629
		1630	&time
		1631	}
		1632
		1633	*now = \&time;
		1634	sub now_update { }
		1635
		1636	sub _poll {
		1637	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1638	}
		1639
		1640	# default implementation for ->condvar
		1641	# in fact, the default should not be overwritten
		1642
		1643	sub condvar {
		1644	eval q{ # poor man's autoloading {}
		1645	*condvar = sub {
		1646	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1647	};
		1648
		1649	*AE::cv = sub (;&) {
		1650	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1651	};
		1652	};
		1653	die if $@;
		1654
		1655	&condvar
		1656	}
		1657
		1658	# default implementation for ->signal
		1659
		1660	our $HAVE_ASYNC_INTERRUPT;
		1661
		1662	sub _have_async_interrupt() {
		1663	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1664	&& eval "use Async::Interrupt 1.02 (); 1")
		1665	unless defined $HAVE_ASYNC_INTERRUPT;
		1666
		1667	$HAVE_ASYNC_INTERRUPT
		1668	}
		1669
		1670	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1671	our (%SIG_ASY, %SIG_ASY_W);
		1672	our ($SIG_COUNT, $SIG_TW);
		1673
		1674	# install a dummy wakeup watcher to reduce signal catching latency
		1675	# used by Impls
		1676	sub _sig_add() {
		1677	unless ($SIG_COUNT++) {
		1678	# try to align timer on a full-second boundary, if possible
		1679	my $NOW = AE::now;
		1680
		1681	$SIG_TW = AE::timer
		1682	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1683	$MAX_SIGNAL_LATENCY,
		1684	sub { } # just for the PERL_ASYNC_CHECK
		1685	;
		1686	}
		1687	}
		1688
		1689	sub _sig_del {
		1690	undef $SIG_TW
		1691	unless --$SIG_COUNT;
		1692	}
		1693
		1694	our $_sig_name_init; $_sig_name_init = sub {
		1695	eval q{ # poor man's autoloading {}
		1696	undef $_sig_name_init;
		1697
		1698	if (_have_async_interrupt) {
		1699	*sig2num = \&Async::Interrupt::sig2num;
		1700	*sig2name = \&Async::Interrupt::sig2name;
		1701	} else {
		1702	require Config;
		1703
		1704	my %signame2num;
		1705	@signame2num{ split ' ', $Config::Config{sig_name} }
		1706	= split ' ', $Config::Config{sig_num};
		1707
		1708	my @signum2name;
		1709	@signum2name[values %signame2num] = keys %signame2num;
		1710
		1711	*sig2num = sub($) {
		1712	$_[0] > 0 ? shift : $signame2num{+shift}
		1713	};
		1714	*sig2name = sub ($) {
		1715	$_[0] > 0 ? $signum2name[+shift] : shift
		1716	};
		1717	}
		1718	};
		1719	die if $@;
		1720	};
		1721
		1722	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1723	sub sig2name($) { &$_sig_name_init; &sig2name }
		1724
		1725	sub signal {
		1726	eval q{ # poor man's autoloading {}
		1727	# probe for availability of Async::Interrupt
		1728	if (_have_async_interrupt) {
		1729	AnyEvent::log 8 => "using Async::Interrupt for race-free signal handling.";
		1730
		1731	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1732	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1733
		1734	} else {
		1735	AnyEvent::log 8 => "using emulated perl signal handling with latency timer.";
		1736
		1737	if (AnyEvent::WIN32) {
		1738	require AnyEvent::Util;
		1739
		1740	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1741	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1742	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1743	} else {
		1744	pipe $SIGPIPE_R, $SIGPIPE_W;
		1745	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1746	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1747
		1748	# not strictly required, as $^F is normally 2, but let's make sure...
		1749	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1750	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1751	}
		1752
		1753	$SIGPIPE_R
		1754	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1755
		1756	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1757	}
		1758
		1759	*signal = $HAVE_ASYNC_INTERRUPT
		1760	? sub {
		1761	my (undef, %arg) = @_;
		1762
		1763	# async::interrupt
		1764	my $signal = sig2num $arg{signal};
		1765	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1766
		1767	$SIG_ASY{$signal} ||= new Async::Interrupt
		1768	cb => sub { undef $SIG_EV{$signal} },
		1769	signal => $signal,
		1770	pipe => [$SIGPIPE_R->filenos],
		1771	pipe_autodrain => 0,
		1772	;
		1773
		1774	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1775	}
		1776	: sub {
		1777	my (undef, %arg) = @_;
		1778
		1779	# pure perl
		1780	my $signal = sig2name $arg{signal};
		1781	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1782
		1783	$SIG{$signal} ||= sub {
486	last;	1784	local $!;
		1785	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1786	undef $SIG_EV{$signal};
487	}	1787	};
		1788
		1789	# can't do signal processing without introducing races in pure perl,
		1790	# so limit the signal latency.
		1791	_sig_add;
		1792
		1793	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1794	}
		1795	;
		1796
		1797	*AnyEvent::Base::signal::DESTROY = sub {
		1798	my ($signal, $cb) = @{$_[0]};
		1799
		1800	_sig_del;
		1801
		1802	delete $SIG_CB{$signal}{$cb};
		1803
		1804	$HAVE_ASYNC_INTERRUPT
		1805	? delete $SIG_ASY{$signal}
		1806	: # delete doesn't work with older perls - they then
		1807	# print weird messages, or just unconditionally exit
		1808	# instead of getting the default action.
		1809	undef $SIG{$signal}
		1810	unless keys %{ $SIG_CB{$signal} };
		1811	};
		1812
		1813	*_signal_exec = sub {
		1814	$HAVE_ASYNC_INTERRUPT
		1815	? $SIGPIPE_R->drain
		1816	: sysread $SIGPIPE_R, (my $dummy), 9;
		1817
		1818	while (%SIG_EV) {
		1819	for (keys %SIG_EV) {
		1820	delete $SIG_EV{$_};
		1821	&$_ for values %{ $SIG_CB{$_} || {} };
488	}	1822	}
489
490	$MODEL
491	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.";
492	}	1823	}
493	}	1824	};
494
495	unshift @ISA, $MODEL;
496	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
497	}
498
499	$MODEL
500	}
501
502	sub AUTOLOAD {
503	(my $func = $AUTOLOAD) =~ s/.*://;
504
505	$method{$func}
506	or croak "$func: not a valid method for AnyEvent objects";
507
508	detect unless $MODEL;
509
510	my $class = shift;
511	$class->$func (@_);
512	}
513
514	package AnyEvent::Base;
515
516	# default implementation for ->condvar, ->wait, ->broadcast
517
518	sub condvar {
519	bless \my $flag, "AnyEvent::Base::CondVar"
520	}
521
522	sub AnyEvent::Base::CondVar::broadcast {
523	${$_[0]}++;
524	}
525
526	sub AnyEvent::Base::CondVar::wait {
527	AnyEvent->one_event while !${$_[0]};
528	}
529
530	# default implementation for ->signal
531
532	our %SIG_CB;
533
534	sub signal {
535	my (undef, %arg) = @_;
536
537	my $signal = uc $arg{signal}
538	or Carp::croak "required option 'signal' is missing";
539
540	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
541	$SIG{$signal} ||= sub {
542	$_->() for values %{ $SIG_CB{$signal} || {} };
543	};	1825	};
		1826	die if $@;
544		1827
545	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1828	&signal
546	}
547
548	sub AnyEvent::Base::Signal::DESTROY {
549	my ($signal, $cb) = @{$_[0]};
550
551	delete $SIG_CB{$signal}{$cb};
552
553	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
554	}	1829	}
555		1830
556	# default implementation for ->child	1831	# default implementation for ->child
557		1832
558	our %PID_CB;	1833	our %PID_CB;
559	our $CHLD_W;	1834	our $CHLD_W;
560	our $CHLD_DELAY_W;	1835	our $CHLD_DELAY_W;
561	our $PID_IDLE;
562	our $WNOHANG;
563		1836
564	sub _child_wait {	1837	# used by many Impl's
565	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1838	sub _emit_childstatus($$) {
		1839	my (undef, $rpid, $rstatus) = @_;
		1840
		1841	$_->($rpid, $rstatus)
566	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1842	for values %{ $PID_CB{$rpid} || {} },
567	(values %{ $PID_CB{0} || {} });	1843	values %{ $PID_CB{0} || {} };
		1844	}
		1845
		1846	sub child {
		1847	eval q{ # poor man's autoloading {}
		1848	*_sigchld = sub {
		1849	my $pid;
		1850
		1851	AnyEvent->_emit_childstatus ($pid, $?)
		1852	while ($pid = waitpid -1, WNOHANG) > 0;
		1853	};
		1854
		1855	*child = sub {
		1856	my (undef, %arg) = @_;
		1857
		1858	my $pid = $arg{pid};
		1859	my $cb = $arg{cb};
		1860
		1861	$PID_CB{$pid}{$cb+0} = $cb;
		1862
		1863	unless ($CHLD_W) {
		1864	$CHLD_W = AE::signal CHLD => \&_sigchld;
		1865	# child could be a zombie already, so make at least one round
		1866	&_sigchld;
		1867	}
		1868
		1869	bless [$pid, $cb+0], "AnyEvent::Base::child"
		1870	};
		1871
		1872	*AnyEvent::Base::child::DESTROY = sub {
		1873	my ($pid, $icb) = @{$_[0]};
		1874
		1875	delete $PID_CB{$pid}{$icb};
		1876	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
		1877
		1878	undef $CHLD_W unless keys %PID_CB;
		1879	};
		1880	};
		1881	die if $@;
		1882
		1883	&child
		1884	}
		1885
		1886	# idle emulation is done by simply using a timer, regardless
		1887	# of whether the process is idle or not, and not letting
		1888	# the callback use more than 50% of the time.
		1889	sub idle {
		1890	eval q{ # poor man's autoloading {}
		1891	*idle = sub {
		1892	my (undef, %arg) = @_;
		1893
		1894	my ($cb, $w, $rcb) = $arg{cb};
		1895
		1896	$rcb = sub {
		1897	if ($cb) {
		1898	$w = AE::time;
		1899	&$cb;
		1900	$w = AE::time - $w;
		1901
		1902	# never use more then 50% of the time for the idle watcher,
		1903	# within some limits
		1904	$w = 0.0001 if $w < 0.0001;
		1905	$w = 5 if $w > 5;
		1906
		1907	$w = AE::timer $w, 0, $rcb;
		1908	} else {
		1909	# clean up...
		1910	undef $w;
		1911	undef $rcb;
		1912	}
		1913	};
		1914
		1915	$w = AE::timer 0.05, 0, $rcb;
		1916
		1917	bless \\$cb, "AnyEvent::Base::idle"
		1918	};
		1919
		1920	*AnyEvent::Base::idle::DESTROY = sub {
		1921	undef $${$_[0]};
		1922	};
		1923	};
		1924	die if $@;
		1925
		1926	&idle
		1927	}
		1928
		1929	package AnyEvent::CondVar;
		1930
		1931	our @ISA = AnyEvent::CondVar::Base::;
		1932
		1933	# only to be used for subclassing
		1934	sub new {
		1935	my $class = shift;
		1936	bless AnyEvent->condvar (@_), $class
		1937	}
		1938
		1939	package AnyEvent::CondVar::Base;
		1940
		1941	#use overload
		1942	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1943	# fallback => 1;
		1944
		1945	# save 300+ kilobytes by dirtily hardcoding overloading
		1946	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1947	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1948	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1949	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1950
		1951	our $WAITING;
		1952
		1953	sub _send {
		1954	# nop
		1955	}
		1956
		1957	sub _wait {
		1958	AnyEvent->_poll until $_[0]{_ae_sent};
		1959	}
		1960
		1961	sub send {
		1962	my $cv = shift;
		1963	$cv->{_ae_sent} = [@_];
		1964	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1965	$cv->_send;
		1966	}
		1967
		1968	sub croak {
		1969	$_[0]{_ae_croak} = $_[1];
		1970	$_[0]->send;
		1971	}
		1972
		1973	sub ready {
		1974	$_[0]{_ae_sent}
		1975	}
		1976
		1977	sub recv {
		1978	unless ($_[0]{_ae_sent}) {
		1979	$WAITING
		1980	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1981
		1982	local $WAITING = 1;
		1983	$_[0]->_wait;
568	}	1984	}
569		1985
570	undef $PID_IDLE;	1986	$_[0]{_ae_croak}
571	}	1987	and Carp::croak $_[0]{_ae_croak};
572		1988
573	sub _sigchld {	1989	wantarray
574	# make sure we deliver these changes "synchronous" with the event loop.	1990	? @{ $_[0]{_ae_sent} }
575	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1991	: $_[0]{_ae_sent}[0]
576	undef $CHLD_DELAY_W;
577	&_child_wait;
578	});
579	}	1992	}
580		1993
581	sub child {	1994	sub cb {
582	my (undef, %arg) = @_;	1995	my $cv = shift;
583		1996
584	defined (my $pid = $arg{pid} + 0)	1997	@_
585	or Carp::croak "required option 'pid' is missing";	1998	and $cv->{_ae_cb} = shift
		1999	and $cv->{_ae_sent}
		2000	and (delete $cv->{_ae_cb})->($cv);
586		2001
587	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	2002	$cv->{_ae_cb}
588
589	unless ($WNOHANG) {
590	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;
591	}
592
593	unless ($CHLD_W) {
594	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
595	# child could be a zombie already, so make at least one round
596	&_sigchld;
597	}
598
599	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
600	}	2003	}
601		2004
602	sub AnyEvent::Base::Child::DESTROY {	2005	sub begin {
603	my ($pid, $cb) = @{$_[0]};	2006	++$_[0]{_ae_counter};
604		2007	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
605	delete $PID_CB{$pid}{$cb};
606	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
607
608	undef $CHLD_W unless keys %PID_CB;
609	}	2008	}
		2009
		2010	sub end {
		2011	return if --$_[0]{_ae_counter};
		2012	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		2013	}
		2014
		2015	# undocumented/compatibility with pre-3.4
		2016	*broadcast = \&send;
		2017	*wait = \&recv;
		2018
		2019	=head1 ERROR AND EXCEPTION HANDLING
		2020
		2021	In general, AnyEvent does not do any error handling - it relies on the
		2022	caller to do that if required. The L<AnyEvent::Strict> module (see also
		2023	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		2024	checking of all AnyEvent methods, however, which is highly useful during
		2025	development.
		2026
		2027	As for exception handling (i.e. runtime errors and exceptions thrown while
		2028	executing a callback), this is not only highly event-loop specific, but
		2029	also not in any way wrapped by this module, as this is the job of the main
		2030	program.
		2031
		2032	The pure perl event loop simply re-throws the exception (usually
		2033	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		2034	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		2035	so on.
		2036
		2037	=head1 ENVIRONMENT VARIABLES
		2038
		2039	AnyEvent supports a number of environment variables that tune the
		2040	runtime behaviour. They are usually evaluated when AnyEvent is
		2041	loaded, initialised, or a submodule that uses them is loaded. Many of
		2042	them also cause AnyEvent to load additional modules - for example,
		2043	C<PERL_ANYEVENT_DEBUG_WRAP> causes the L<AnyEvent::Debug> module to be
		2044	loaded.
		2045
		2046	All the environment variables documented here start with
		2047	C<PERL_ANYEVENT_>, which is what AnyEvent considers its own
		2048	namespace. Other modules are encouraged (but by no means required) to use
		2049	C<PERL_ANYEVENT_SUBMODULE> if they have registered the AnyEvent::Submodule
		2050	namespace on CPAN, for any submodule. For example, L<AnyEvent::HTTP> could
		2051	be expected to use C<PERL_ANYEVENT_HTTP_PROXY> (it should not access env
		2052	variables starting with C<AE_>, see below).
		2053
		2054	All variables can also be set via the C<AE_> prefix, that is, instead
		2055	of setting C<PERL_ANYEVENT_VERBOSE> you can also set C<AE_VERBOSE>. In
		2056	case there is a clash btween anyevent and another program that uses
		2057	C<AE_something> you can set the corresponding C<PERL_ANYEVENT_something>
		2058	variable to the empty string, as those variables take precedence.
		2059
		2060	When AnyEvent is first loaded, it copies all C<AE_xxx> env variables
		2061	to their C<PERL_ANYEVENT_xxx> counterpart unless that variable already
		2062	exists. If taint mode is on, then AnyEvent will remove I<all> environment
		2063	variables starting with C<PERL_ANYEVENT_> from C<%ENV> (or replace them
		2064	with C<undef> or the empty string, if the corresaponding C<AE_> variable
		2065	is set).
		2066
		2067	The exact algorithm is currently:
		2068
		2069	1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
		2070	2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
		2071	3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
		2072
		2073	This ensures that child processes will not see the C<AE_> variables.
		2074
		2075	The following environment variables are currently known to AnyEvent:
		2076
		2077	=over 4
		2078
		2079	=item C<PERL_ANYEVENT_VERBOSE>
		2080
		2081	By default, AnyEvent will only log messages with loglevel C<3>
		2082	(C<critical>) or higher (see L<AnyEvent::Log>). You can set this
		2083	environment variable to a numerical loglevel to make AnyEvent more (or
		2084	less) talkative.
		2085
		2086	If you want to do more than just set the global logging level
		2087	you should have a look at C<PERL_ANYEVENT_LOG>, which allows much more
		2088	complex specifications.
		2089
		2090	When set to C<0> (C<off>), then no messages whatsoever will be logged with
		2091	the default logging settings.
		2092
		2093	When set to C<5> or higher (C<warn>), causes AnyEvent to warn about
		2094	unexpected conditions, such as not being able to load the event model
		2095	specified by C<PERL_ANYEVENT_MODEL>, or a guard callback throwing an
		2096	exception - this is the minimum recommended level.
		2097
		2098	When set to C<7> or higher (info), cause AnyEvent to report which event model it
		2099	chooses.
		2100
		2101	When set to C<8> or higher (debug), then AnyEvent will report extra information on
		2102	which optional modules it loads and how it implements certain features.
		2103
		2104	=item C<PERL_ANYEVENT_LOG>
		2105
		2106	Accepts rather complex logging specifications. For example, you could log
		2107	all C<debug> messages of some module to stderr, warnings and above to
		2108	stderr, and errors and above to syslog, with:
		2109
		2110	PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
		2111
		2112	For the rather extensive details, see L<AnyEvent::Log>.
		2113
		2114	This variable is evaluated when AnyEvent (or L<AnyEvent::Log>) is loaded,
		2115	so will take effect even before AnyEvent has initialised itself.
		2116
		2117	Note that specifying this environment variable causes the L<AnyEvent::Log>
		2118	module to be loaded, while C<PERL_ANYEVENT_VERBOSE> does not, so only
		2119	using the latter saves a few hundred kB of memory until the first message
		2120	is being logged.
		2121
		2122	=item C<PERL_ANYEVENT_STRICT>
		2123
		2124	AnyEvent does not do much argument checking by default, as thorough
		2125	argument checking is very costly. Setting this variable to a true value
		2126	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		2127	check the arguments passed to most method calls. If it finds any problems,
		2128	it will croak.
		2129
		2130	In other words, enables "strict" mode.
		2131
		2132	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
		2133	>>, it is definitely recommended to keep it off in production. Keeping
		2134	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		2135	can be very useful, however.
		2136
		2137	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		2138
		2139	If this env variable is nonempty, then its contents will be interpreted by
		2140	C<AnyEvent::Socket::parse_hostport> and C<AnyEvent::Debug::shell> (after
		2141	replacing every occurance of C<$$> by the process pid). The shell object
		2142	is saved in C<$AnyEvent::Debug::SHELL>.
		2143
		2144	This happens when the first watcher is created.
		2145
		2146	For example, to bind a debug shell on a unix domain socket in
		2147	F<< /tmp/debug<pid>.sock >>, you could use this:
		2148
		2149	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		2150	# connect with e.g.: socat readline /tmp/debug123.sock
		2151
		2152	Or to bind to tcp port 4545 on localhost:
		2153
		2154	PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
		2155	# connect with e.g.: telnet localhost 4545
		2156
		2157	Note that creating sockets in F</tmp> or on localhost is very unsafe on
		2158	multiuser systems.
		2159
		2160	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2161
		2162	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2163	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
		2164
		2165	=item C<PERL_ANYEVENT_MODEL>
		2166
		2167	This can be used to specify the event model to be used by AnyEvent, before
		2168	auto detection and -probing kicks in.
		2169
		2170	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2171	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
		2172	resulting module name is loaded and - if the load was successful - used as
		2173	event model backend. If it fails to load then AnyEvent will proceed with
		2174	auto detection and -probing.
		2175
		2176	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2177	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2178	the end of a string designates a module name and quotes it appropriately).
		2179
		2180	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
		2181	could start your program like this:
		2182
		2183	PERL_ANYEVENT_MODEL=Perl perl ...
		2184
		2185	=item C<PERL_ANYEVENT_PROTOCOLS>
		2186
		2187	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		2188	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		2189	of auto probing).
		2190
		2191	Must be set to a comma-separated list of protocols or address families,
		2192	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		2193	used, and preference will be given to protocols mentioned earlier in the
		2194	list.
		2195
		2196	This variable can effectively be used for denial-of-service attacks
		2197	against local programs (e.g. when setuid), although the impact is likely
		2198	small, as the program has to handle conenction and other failures anyways.
		2199
		2200	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		2201	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		2202	- only support IPv4, never try to resolve or contact IPv6
		2203	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		2204	IPv6, but prefer IPv6 over IPv4.
		2205
		2206	=item C<PERL_ANYEVENT_HOSTS>
		2207
		2208	This variable, if specified, overrides the F</etc/hosts> file used by
		2209	L<AnyEvent::Socket>C<::resolve_sockaddr>, i.e. hosts aliases will be read
		2210	from that file instead.
		2211
		2212	=item C<PERL_ANYEVENT_EDNS0>
		2213
		2214	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension for
		2215	DNS. This extension is generally useful to reduce DNS traffic, especially
		2216	when DNSSEC is involved, but some (broken) firewalls drop such DNS
		2217	packets, which is why it is off by default.
		2218
		2219	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		2220	EDNS0 in its DNS requests.
		2221
		2222	=item C<PERL_ANYEVENT_MAX_FORKS>
		2223
		2224	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		2225	will create in parallel.
		2226
		2227	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2228
		2229	The default value for the C<max_outstanding> parameter for the default DNS
		2230	resolver - this is the maximum number of parallel DNS requests that are
		2231	sent to the DNS server.
		2232
		2233	=item C<PERL_ANYEVENT_MAX_SIGNAL_LATENCY>
		2234
		2235	Perl has inherently racy signal handling (you can basically choose between
		2236	losing signals and memory corruption) - pure perl event loops (including
		2237	C<AnyEvent::Loop>, when C<Async::Interrupt> isn't available) therefore
		2238	have to poll regularly to avoid losing signals.
		2239
		2240	Some event loops are racy, but don't poll regularly, and some event loops
		2241	are written in C but are still racy. For those event loops, AnyEvent
		2242	installs a timer that regularly wakes up the event loop.
		2243
		2244	By default, the interval for this timer is C<10> seconds, but you can
		2245	override this delay with this environment variable (or by setting
		2246	the C<$AnyEvent::MAX_SIGNAL_LATENCY> variable before creating signal
		2247	watchers).
		2248
		2249	Lower values increase CPU (and energy) usage, higher values can introduce
		2250	long delays when reaping children or waiting for signals.
		2251
		2252	The L<AnyEvent::Async> module, if available, will be used to avoid this
		2253	polling (with most event loops).
		2254
		2255	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2256
		2257	The absolute path to a F<resolv.conf>-style file to use instead of
		2258	F</etc/resolv.conf> (or the OS-specific configuration) in the default
		2259	resolver, or the empty string to select the default configuration.
		2260
		2261	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2262
		2263	When neither C<ca_file> nor C<ca_path> was specified during
		2264	L<AnyEvent::TLS> context creation, and either of these environment
		2265	variables are nonempty, they will be used to specify CA certificate
		2266	locations instead of a system-dependent default.
		2267
		2268	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2269
		2270	When these are set to C<1>, then the respective modules are not
		2271	loaded. Mostly good for testing AnyEvent itself.
		2272
		2273	=back
610		2274
611	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2275	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
612		2276
613	This is an advanced topic that you do not normally need to use AnyEvent in	2277	This is an advanced topic that you do not normally need to use AnyEvent in
614	a module. This section is only of use to event loop authors who want to	2278	a module. This section is only of use to event loop authors who want to
…		…
649	I<rxvt-unicode> also cheats a bit by not providing blocking access to	2313	I<rxvt-unicode> also cheats a bit by not providing blocking access to
650	condition variables: code blocking while waiting for a condition will	2314	condition variables: code blocking while waiting for a condition will
651	C<die>. This still works with most modules/usages, and blocking calls must	2315	C<die>. This still works with most modules/usages, and blocking calls must
652	not be done in an interactive application, so it makes sense.	2316	not be done in an interactive application, so it makes sense.
653		2317
654	=head1 ENVIRONMENT VARIABLES
655
656	The following environment variables are used by this module:
657
658	=over 4
659
660	=item C<PERL_ANYEVENT_VERBOSE>
661
662	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
663	model it chooses.
664
665	=item C<PERL_ANYEVENT_MODEL>
666
667	This can be used to specify the event model to be used by AnyEvent, before
668	autodetection and -probing kicks in. It must be a string consisting
669	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
670	and the resulting module name is loaded and if the load was successful,
671	used as event model. If it fails to load AnyEvent will proceed with
672	autodetection and -probing.
673
674	This functionality might change in future versions.
675
676	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
677	could start your program like this:
678
679	PERL_ANYEVENT_MODEL=Perl perl ...
680
681	=back
682
683	=head1 EXAMPLE PROGRAM	2318	=head1 EXAMPLE PROGRAM
684		2319
685	The following program uses an IO watcher to read data from STDIN, a timer	2320	The following program uses an I/O watcher to read data from STDIN, a timer
686	to display a message once per second, and a condition variable to quit the	2321	to display a message once per second, and a condition variable to quit the
687	program when the user enters quit:	2322	program when the user enters quit:
688		2323
689	use AnyEvent;	2324	use AnyEvent;
690		2325
…		…
695	poll => 'r',	2330	poll => 'r',
696	cb => sub {	2331	cb => sub {
697	warn "io event <$_[0]>\n"; # will always output <r>	2332	warn "io event <$_[0]>\n"; # will always output <r>
698	chomp (my $input = <STDIN>); # read a line	2333	chomp (my $input = <STDIN>); # read a line
699	warn "read: $input\n"; # output what has been read	2334	warn "read: $input\n"; # output what has been read
700	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	2335	$cv->send if $input =~ /^q/i; # quit program if /^q/i
701	},	2336	},
702	);	2337	);
703		2338
704	my $time_watcher; # can only be used once
705
706	sub new_timer {
707	$timer = AnyEvent->timer (after => 1, cb => sub {	2339	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
708	warn "timeout\n"; # print 'timeout' about every second	2340	warn "timeout\n"; # print 'timeout' at most every second
709	&new_timer; # and restart the time
710	});	2341	});
711	}
712		2342
713	new_timer; # create first timer
714
715	$cv->wait; # wait until user enters /^q/i	2343	$cv->recv; # wait until user enters /^q/i
716		2344
717	=head1 REAL-WORLD EXAMPLE	2345	=head1 REAL-WORLD EXAMPLE
718		2346
719	Consider the L<Net::FCP> module. It features (among others) the following	2347	Consider the L<Net::FCP> module. It features (among others) the following
720	API calls, which are to freenet what HTTP GET requests are to http:	2348	API calls, which are to freenet what HTTP GET requests are to http:
…		…
770	syswrite $txn->{fh}, $txn->{request}	2398	syswrite $txn->{fh}, $txn->{request}
771	or die "connection or write error";	2399	or die "connection or write error";
772	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	2400	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
773		2401
774	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	2402	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
775	result and signals any possible waiters that the request ahs finished:	2403	result and signals any possible waiters that the request has finished:
776		2404
777	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	2405	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
778		2406
779	if (end-of-file or data complete) {	2407	if (end-of-file or data complete) {
780	$txn->{result} = $txn->{buf};	2408	$txn->{result} = $txn->{buf};
781	$txn->{finished}->broadcast;	2409	$txn->{finished}->send;
782	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	2410	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
783	}	2411	}
784		2412
785	The C<result> method, finally, just waits for the finished signal (if the	2413	The C<result> method, finally, just waits for the finished signal (if the
786	request was already finished, it doesn't wait, of course, and returns the	2414	request was already finished, it doesn't wait, of course, and returns the
787	data:	2415	data:
788		2416
789	$txn->{finished}->wait;	2417	$txn->{finished}->recv;
790	return $txn->{result};	2418	return $txn->{result};
791		2419
792	The actual code goes further and collects all errors (C<die>s, exceptions)	2420	The actual code goes further and collects all errors (C<die>s, exceptions)
793	that occured during request processing. The C<result> method detects	2421	that occurred during request processing. The C<result> method detects
794	whether an exception as thrown (it is stored inside the $txn object)	2422	whether an exception as thrown (it is stored inside the $txn object)
795	and just throws the exception, which means connection errors and other	2423	and just throws the exception, which means connection errors and other
796	problems get reported tot he code that tries to use the result, not in a	2424	problems get reported to the code that tries to use the result, not in a
797	random callback.	2425	random callback.
798		2426
799	All of this enables the following usage styles:	2427	All of this enables the following usage styles:
800		2428
801	1. Blocking:	2429	1. Blocking:
…		…
829		2457
830	my $quit = AnyEvent->condvar;	2458	my $quit = AnyEvent->condvar;
831		2459
832	$fcp->txn_client_get ($url)->cb (sub {	2460	$fcp->txn_client_get ($url)->cb (sub {
833	...	2461	...
834	$quit->broadcast;	2462	$quit->send;
835	});	2463	});
836		2464
837	$quit->wait;	2465	$quit->recv;
		2466
		2467
		2468	=head1 BENCHMARKS
		2469
		2470	To give you an idea of the performance and overheads that AnyEvent adds
		2471	over the event loops themselves and to give you an impression of the speed
		2472	of various event loops I prepared some benchmarks.
		2473
		2474	=head2 BENCHMARKING ANYEVENT OVERHEAD
		2475
		2476	Here is a benchmark of various supported event models used natively and
		2477	through AnyEvent. The benchmark creates a lot of timers (with a zero
		2478	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
		2479	which it is), lets them fire exactly once and destroys them again.
		2480
		2481	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
		2482	distribution. It uses the L<AE> interface, which makes a real difference
		2483	for the EV and Perl backends only.
		2484
		2485	=head3 Explanation of the columns
		2486
		2487	I<watcher> is the number of event watchers created/destroyed. Since
		2488	different event models feature vastly different performances, each event
		2489	loop was given a number of watchers so that overall runtime is acceptable
		2490	and similar between tested event loop (and keep them from crashing): Glib
		2491	would probably take thousands of years if asked to process the same number
		2492	of watchers as EV in this benchmark.
		2493
		2494	I<bytes> is the number of bytes (as measured by the resident set size,
		2495	RSS) consumed by each watcher. This method of measuring captures both C
		2496	and Perl-based overheads.
		2497
		2498	I<create> is the time, in microseconds (millionths of seconds), that it
		2499	takes to create a single watcher. The callback is a closure shared between
		2500	all watchers, to avoid adding memory overhead. That means closure creation
		2501	and memory usage is not included in the figures.
		2502
		2503	I<invoke> is the time, in microseconds, used to invoke a simple
		2504	callback. The callback simply counts down a Perl variable and after it was
		2505	invoked "watcher" times, it would C<< ->send >> a condvar once to
		2506	signal the end of this phase.
		2507
		2508	I<destroy> is the time, in microseconds, that it takes to destroy a single
		2509	watcher.
		2510
		2511	=head3 Results
		2512
		2513	name watchers bytes create invoke destroy comment
		2514	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
		2515	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
		2516	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
		2517	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
		2518	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
		2519	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2520	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2521	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
		2522	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
		2523	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
		2524	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
		2525	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
		2526
		2527	=head3 Discussion
		2528
		2529	The benchmark does I<not> measure scalability of the event loop very
		2530	well. For example, a select-based event loop (such as the pure perl one)
		2531	can never compete with an event loop that uses epoll when the number of
		2532	file descriptors grows high. In this benchmark, all events become ready at
		2533	the same time, so select/poll-based implementations get an unnatural speed
		2534	boost.
		2535
		2536	Also, note that the number of watchers usually has a nonlinear effect on
		2537	overall speed, that is, creating twice as many watchers doesn't take twice
		2538	the time - usually it takes longer. This puts event loops tested with a
		2539	higher number of watchers at a disadvantage.
		2540
		2541	To put the range of results into perspective, consider that on the
		2542	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		2543	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		2544	cycles with POE.
		2545
		2546	C<EV> is the sole leader regarding speed and memory use, which are both
		2547	maximal/minimal, respectively. When using the L<AE> API there is zero
		2548	overhead (when going through the AnyEvent API create is about 5-6 times
		2549	slower, with other times being equal, so still uses far less memory than
		2550	any other event loop and is still faster than Event natively).
		2551
		2552	The pure perl implementation is hit in a few sweet spots (both the
		2553	constant timeout and the use of a single fd hit optimisations in the perl
		2554	interpreter and the backend itself). Nevertheless this shows that it
		2555	adds very little overhead in itself. Like any select-based backend its
		2556	performance becomes really bad with lots of file descriptors (and few of
		2557	them active), of course, but this was not subject of this benchmark.
		2558
		2559	The C<Event> module has a relatively high setup and callback invocation
		2560	cost, but overall scores in on the third place.
		2561
		2562	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2563	when using its pure perl backend.
		2564
		2565	C<Glib>'s memory usage is quite a bit higher, but it features a
		2566	faster callback invocation and overall ends up in the same class as
		2567	C<Event>. However, Glib scales extremely badly, doubling the number of
		2568	watchers increases the processing time by more than a factor of four,
		2569	making it completely unusable when using larger numbers of watchers
		2570	(note that only a single file descriptor was used in the benchmark, so
		2571	inefficiencies of C<poll> do not account for this).
		2572
		2573	The C<Tk> adaptor works relatively well. The fact that it crashes with
		2574	more than 2000 watchers is a big setback, however, as correctness takes
		2575	precedence over speed. Nevertheless, its performance is surprising, as the
		2576	file descriptor is dup()ed for each watcher. This shows that the dup()
		2577	employed by some adaptors is not a big performance issue (it does incur a
		2578	hidden memory cost inside the kernel which is not reflected in the figures
		2579	above).
		2580
		2581	C<POE>, regardless of underlying event loop (whether using its pure perl
		2582	select-based backend or the Event module, the POE-EV backend couldn't
		2583	be tested because it wasn't working) shows abysmal performance and
		2584	memory usage with AnyEvent: Watchers use almost 30 times as much memory
		2585	as EV watchers, and 10 times as much memory as Event (the high memory
		2586	requirements are caused by requiring a session for each watcher). Watcher
		2587	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		2588	implementation.
		2589
		2590	The design of the POE adaptor class in AnyEvent can not really account
		2591	for the performance issues, though, as session creation overhead is
		2592	small compared to execution of the state machine, which is coded pretty
		2593	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		2594	using multiple sessions is not a good approach, especially regarding
		2595	memory usage, even the author of POE could not come up with a faster
		2596	design).
		2597
		2598	=head3 Summary
		2599
		2600	=over 4
		2601
		2602	=item * Using EV through AnyEvent is faster than any other event loop
		2603	(even when used without AnyEvent), but most event loops have acceptable
		2604	performance with or without AnyEvent.
		2605
		2606	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
		2607	the actual event loop, only with extremely fast event loops such as EV
		2608	does AnyEvent add significant overhead.
		2609
		2610	=item * You should avoid POE like the plague if you want performance or
		2611	reasonable memory usage.
		2612
		2613	=back
		2614
		2615	=head2 BENCHMARKING THE LARGE SERVER CASE
		2616
		2617	This benchmark actually benchmarks the event loop itself. It works by
		2618	creating a number of "servers": each server consists of a socket pair, a
		2619	timeout watcher that gets reset on activity (but never fires), and an I/O
		2620	watcher waiting for input on one side of the socket. Each time the socket
		2621	watcher reads a byte it will write that byte to a random other "server".
		2622
		2623	The effect is that there will be a lot of I/O watchers, only part of which
		2624	are active at any one point (so there is a constant number of active
		2625	fds for each loop iteration, but which fds these are is random). The
		2626	timeout is reset each time something is read because that reflects how
		2627	most timeouts work (and puts extra pressure on the event loops).
		2628
		2629	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
		2630	(1%) are active. This mirrors the activity of large servers with many
		2631	connections, most of which are idle at any one point in time.
		2632
		2633	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
		2634	distribution. It uses the L<AE> interface, which makes a real difference
		2635	for the EV and Perl backends only.
		2636
		2637	=head3 Explanation of the columns
		2638
		2639	I<sockets> is the number of sockets, and twice the number of "servers" (as
		2640	each server has a read and write socket end).
		2641
		2642	I<create> is the time it takes to create a socket pair (which is
		2643	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
		2644
		2645	I<request>, the most important value, is the time it takes to handle a
		2646	single "request", that is, reading the token from the pipe and forwarding
		2647	it to another server. This includes deleting the old timeout and creating
		2648	a new one that moves the timeout into the future.
		2649
		2650	=head3 Results
		2651
		2652	name sockets create request
		2653	EV 20000 62.66 7.99
		2654	Perl 20000 68.32 32.64
		2655	IOAsync 20000 174.06 101.15 epoll
		2656	IOAsync 20000 174.67 610.84 poll
		2657	Event 20000 202.69 242.91
		2658	Glib 20000 557.01 1689.52
		2659	POE 20000 341.54 12086.32 uses POE::Loop::Event
		2660
		2661	=head3 Discussion
		2662
		2663	This benchmark I<does> measure scalability and overall performance of the
		2664	particular event loop.
		2665
		2666	EV is again fastest. Since it is using epoll on my system, the setup time
		2667	is relatively high, though.
		2668
		2669	Perl surprisingly comes second. It is much faster than the C-based event
		2670	loops Event and Glib.
		2671
		2672	IO::Async performs very well when using its epoll backend, and still quite
		2673	good compared to Glib when using its pure perl backend.
		2674
		2675	Event suffers from high setup time as well (look at its code and you will
		2676	understand why). Callback invocation also has a high overhead compared to
		2677	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
		2678	uses select or poll in basically all documented configurations.
		2679
		2680	Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It
		2681	clearly fails to perform with many filehandles or in busy servers.
		2682
		2683	POE is still completely out of the picture, taking over 1000 times as long
		2684	as EV, and over 100 times as long as the Perl implementation, even though
		2685	it uses a C-based event loop in this case.
		2686
		2687	=head3 Summary
		2688
		2689	=over 4
		2690
		2691	=item * The pure perl implementation performs extremely well.
		2692
		2693	=item * Avoid Glib or POE in large projects where performance matters.
		2694
		2695	=back
		2696
		2697	=head2 BENCHMARKING SMALL SERVERS
		2698
		2699	While event loops should scale (and select-based ones do not...) even to
		2700	large servers, most programs we (or I :) actually write have only a few
		2701	I/O watchers.
		2702
		2703	In this benchmark, I use the same benchmark program as in the large server
		2704	case, but it uses only eight "servers", of which three are active at any
		2705	one time. This should reflect performance for a small server relatively
		2706	well.
		2707
		2708	The columns are identical to the previous table.
		2709
		2710	=head3 Results
		2711
		2712	name sockets create request
		2713	EV 16 20.00 6.54
		2714	Perl 16 25.75 12.62
		2715	Event 16 81.27 35.86
		2716	Glib 16 32.63 15.48
		2717	POE 16 261.87 276.28 uses POE::Loop::Event
		2718
		2719	=head3 Discussion
		2720
		2721	The benchmark tries to test the performance of a typical small
		2722	server. While knowing how various event loops perform is interesting, keep
		2723	in mind that their overhead in this case is usually not as important, due
		2724	to the small absolute number of watchers (that is, you need efficiency and
		2725	speed most when you have lots of watchers, not when you only have a few of
		2726	them).
		2727
		2728	EV is again fastest.
		2729
		2730	Perl again comes second. It is noticeably faster than the C-based event
		2731	loops Event and Glib, although the difference is too small to really
		2732	matter.
		2733
		2734	POE also performs much better in this case, but is is still far behind the
		2735	others.
		2736
		2737	=head3 Summary
		2738
		2739	=over 4
		2740
		2741	=item * C-based event loops perform very well with small number of
		2742	watchers, as the management overhead dominates.
		2743
		2744	=back
		2745
		2746	=head2 THE IO::Lambda BENCHMARK
		2747
		2748	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2749	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2750	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2751	shouldn't come as a surprise to anybody). As such, the benchmark is
		2752	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2753	very optimal. But how would AnyEvent compare when used without the extra
		2754	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2755
		2756	The benchmark itself creates an echo-server, and then, for 500 times,
		2757	connects to the echo server, sends a line, waits for the reply, and then
		2758	creates the next connection. This is a rather bad benchmark, as it doesn't
		2759	test the efficiency of the framework or much non-blocking I/O, but it is a
		2760	benchmark nevertheless.
		2761
		2762	name runtime
		2763	Lambda/select 0.330 sec
		2764	+ optimized 0.122 sec
		2765	Lambda/AnyEvent 0.327 sec
		2766	+ optimized 0.138 sec
		2767	Raw sockets/select 0.077 sec
		2768	POE/select, components 0.662 sec
		2769	POE/select, raw sockets 0.226 sec
		2770	POE/select, optimized 0.404 sec
		2771
		2772	AnyEvent/select/nb 0.085 sec
		2773	AnyEvent/EV/nb 0.068 sec
		2774	+state machine 0.134 sec
		2775
		2776	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2777	benchmarks actually make blocking connects and use 100% blocking I/O,
		2778	defeating the purpose of an event-based solution. All of the newly
		2779	written AnyEvent benchmarks use 100% non-blocking connects (using
		2780	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2781	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2782	generally require a lot more bookkeeping and event handling than blocking
		2783	connects (which involve a single syscall only).
		2784
		2785	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2786	offers similar expressive power as POE and IO::Lambda, using conventional
		2787	Perl syntax. This means that both the echo server and the client are 100%
		2788	non-blocking, further placing it at a disadvantage.
		2789
		2790	As you can see, the AnyEvent + EV combination even beats the
		2791	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2792	backend easily beats IO::Lambda and POE.
		2793
		2794	And even the 100% non-blocking version written using the high-level (and
		2795	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2796	higher level ("unoptimised") abstractions by a large margin, even though
		2797	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2798
		2799	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2800	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2801	part of the IO::Lambda distribution and were used without any changes.
		2802
		2803
		2804	=head1 SIGNALS
		2805
		2806	AnyEvent currently installs handlers for these signals:
		2807
		2808	=over 4
		2809
		2810	=item SIGCHLD
		2811
		2812	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2813	emulation for event loops that do not support them natively. Also, some
		2814	event loops install a similar handler.
		2815
		2816	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2817	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2818
		2819	=item SIGPIPE
		2820
		2821	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2822	when AnyEvent gets loaded.
		2823
		2824	The rationale for this is that AnyEvent users usually do not really depend
		2825	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2826	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2827	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2828	some random socket.
		2829
		2830	The rationale for installing a no-op handler as opposed to ignoring it is
		2831	that this way, the handler will be restored to defaults on exec.
		2832
		2833	Feel free to install your own handler, or reset it to defaults.
		2834
		2835	=back
		2836
		2837	=cut
		2838
		2839	undef $SIG{CHLD}
		2840	if $SIG{CHLD} eq 'IGNORE';
		2841
		2842	$SIG{PIPE} = sub { }
		2843	unless defined $SIG{PIPE};
		2844
		2845	=head1 RECOMMENDED/OPTIONAL MODULES
		2846
		2847	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2848	its built-in modules) are required to use it.
		2849
		2850	That does not mean that AnyEvent won't take advantage of some additional
		2851	modules if they are installed.
		2852
		2853	This section explains which additional modules will be used, and how they
		2854	affect AnyEvent's operation.
		2855
		2856	=over 4
		2857
		2858	=item L<Async::Interrupt>
		2859
		2860	This slightly arcane module is used to implement fast signal handling: To
		2861	my knowledge, there is no way to do completely race-free and quick
		2862	signal handling in pure perl. To ensure that signals still get
		2863	delivered, AnyEvent will start an interval timer to wake up perl (and
		2864	catch the signals) with some delay (default is 10 seconds, look for
		2865	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2866
		2867	If this module is available, then it will be used to implement signal
		2868	catching, which means that signals will not be delayed, and the event loop
		2869	will not be interrupted regularly, which is more efficient (and good for
		2870	battery life on laptops).
		2871
		2872	This affects not just the pure-perl event loop, but also other event loops
		2873	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2874
		2875	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2876	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2877	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2878	does nothing for those backends.
		2879
		2880	=item L<EV>
		2881
		2882	This module isn't really "optional", as it is simply one of the backend
		2883	event loops that AnyEvent can use. However, it is simply the best event
		2884	loop available in terms of features, speed and stability: It supports
		2885	the AnyEvent API optimally, implements all the watcher types in XS, does
		2886	automatic timer adjustments even when no monotonic clock is available,
		2887	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2888	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2889	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2890
		2891	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2892	then this module will do nothing for you.
		2893
		2894	=item L<Guard>
		2895
		2896	The guard module, when used, will be used to implement
		2897	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2898	lot less memory), but otherwise doesn't affect guard operation much. It is
		2899	purely used for performance.
		2900
		2901	=item L<JSON> and L<JSON::XS>
		2902
		2903	One of these modules is required when you want to read or write JSON data
		2904	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2905	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2906
		2907	=item L<Net::SSLeay>
		2908
		2909	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2910	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2911	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2912
		2913	=item L<Time::HiRes>
		2914
		2915	This module is part of perl since release 5.008. It will be used when the
		2916	chosen event library does not come with a timing source of its own. The
		2917	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2918	try to use a monotonic clock for timing stability.
		2919
		2920	=back
		2921
838		2922
839	=head1 FORK	2923	=head1 FORK
840		2924
841	Most event libraries are not fork-safe. The ones who are usually are	2925	Most event libraries are not fork-safe. The ones who are usually are
842	because they are so inefficient. Only L<EV> is fully fork-aware.	2926	because they rely on inefficient but fork-safe C<select> or C<poll> calls
		2927	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2928	are usually badly thought-out hacks that are incompatible with fork in
		2929	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2930	continue event-processing in both parent and child (or both, if you know
		2931	what you are doing).
		2932
		2933	This means that, in general, you cannot fork and do event processing in
		2934	the child if the event library was initialised before the fork (which
		2935	usually happens when the first AnyEvent watcher is created, or the library
		2936	is loaded).
843		2937
844	If you have to fork, you must either do so I<before> creating your first	2938	If you have to fork, you must either do so I<before> creating your first
845	watcher OR you must not use AnyEvent at all in the child.	2939	watcher OR you must not use AnyEvent at all in the child OR you must do
		2940	something completely out of the scope of AnyEvent.
		2941
		2942	The problem of doing event processing in the parent I<and> the child
		2943	is much more complicated: even for backends that I<are> fork-aware or
		2944	fork-safe, their behaviour is not usually what you want: fork clones all
		2945	watchers, that means all timers, I/O watchers etc. are active in both
		2946	parent and child, which is almost never what you want. USing C<exec>
		2947	to start worker children from some kind of manage rprocess is usually
		2948	preferred, because it is much easier and cleaner, at the expense of having
		2949	to have another binary.
		2950
846		2951
847	=head1 SECURITY CONSIDERATIONS	2952	=head1 SECURITY CONSIDERATIONS
848		2953
849	AnyEvent can be forced to load any event model via	2954	AnyEvent can be forced to load any event model via
850	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to	2955	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
…		…
854	specified in the variable.	2959	specified in the variable.
855		2960
856	You can make AnyEvent completely ignore this variable by deleting it	2961	You can make AnyEvent completely ignore this variable by deleting it
857	before the first watcher gets created, e.g. with a C<BEGIN> block:	2962	before the first watcher gets created, e.g. with a C<BEGIN> block:
858		2963
859	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2964	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
860		2965
861	use AnyEvent;	2966	use AnyEvent;
		2967
		2968	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		2969	be used to probe what backend is used and gain other information (which is
		2970	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2971	$ENV{PERL_ANYEVENT_STRICT}.
		2972
		2973	Note that AnyEvent will remove I<all> environment variables starting with
		2974	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2975	enabled.
		2976
		2977
		2978	=head1 BUGS
		2979
		2980	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2981	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2982	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2983	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2984	pronounced).
		2985
862		2986
863	=head1 SEE ALSO	2987	=head1 SEE ALSO
864		2988
865	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	2989	Tutorial/Introduction: L<AnyEvent::Intro>.
866	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
867	L<Event::Lib>, L<Qt>.
868		2990
869	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	2991	FAQ: L<AnyEvent::FAQ>.
		2992
		2993	Utility functions: L<AnyEvent::Util> (misc. grab-bag), L<AnyEvent::Log>
		2994	(simply logging).
		2995
		2996	Development/Debugging: L<AnyEvent::Strict> (stricter checking),
		2997	L<AnyEvent::Debug> (interactive shell, watcher tracing).
		2998
		2999	Supported event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>,
		3000	L<Glib::EV>, L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>,
		3001	L<Qt>, L<POE>, L<FLTK>.
		3002
		3003	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
		3004	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
		3005	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
870	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	3006	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>,
871	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
872	L<AnyEvent::Impl::Qt>.	3007	L<AnyEvent::Impl::FLTK>.
873		3008
		3009	Non-blocking handles, pipes, stream sockets, TCP clients and
		3010	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
		3011
		3012	Asynchronous DNS: L<AnyEvent::DNS>.
		3013
		3014	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		3015
874	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	3016	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		3017	L<AnyEvent::HTTP>.
		3018
875		3019
876	=head1 AUTHOR	3020	=head1 AUTHOR
877		3021
878	Marc Lehmann <schmorp@schmorp.de>	3022	Marc Lehmann <schmorp@schmorp.de>
879	http://home.schmorp.de/	3023	http://home.schmorp.de/
880		3024
881	=cut	3025	=cut
882		3026
883	1	3027	1
884		3028

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