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Revision 1.389 by root, Tue Oct 4 05:34:50 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, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt,
		6	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
20	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
		40	# use a condvar in callback mode:
		41	$w->cb (sub { $_[0]->recv });
22		42
23	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
24		44
25	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	46	in a tutorial or some gentle introduction, have a look at the
27	L<AnyEvent::Intro> manpage.	47	L<AnyEvent::Intro> manpage.
28		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.
		58
29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
30		60
31	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
32	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
33		63
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	64	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	65	policy> and AnyEvent is I<small and efficient>.
36		66
37	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
38	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
39	pragmatic way. For event models and certain classes of immortals alike,	69	pragmatic way. For event models and certain classes of immortals alike,
40	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,
41	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
42	helps hiding the differences between those event loops.	72	cannot change this, but it can hide the differences between those event
		73	loops.
43		74
44	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
45	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
46	religion, a way of living, and most importantly: without forcing your	77	religion, a way of living, and most importantly: without forcing your
47	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
48	model you use.	79	model you use.
49		80
50	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
51	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
52	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
53	cannot use anything else, as it is simply incompatible to everything that	84	cannot use anything else, as they are simply incompatible to everything
54	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
55	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.
56		87
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	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
59	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
60	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
61	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
62	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
63	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,
64	event loops to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
65		96
66	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
67	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
68	modules, you get an enormous amount of code and strict rules you have to	99	modules, you get an enormous amount of code and strict rules you have to
69	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
70	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
71	technically possible.	102	technically possible.
72		103
73	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
74	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
80	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
81	model, you should I<not> use this module.	112	model, you should I<not> use this module.
82		113
83	=head1 DESCRIPTION	114	=head1 DESCRIPTION
84		115
85	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
86	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
87	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
88	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
89		120
90	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>
91	module.	122	module.
92		123
93	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
94	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
95	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
96	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	127	L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
97	L<POE>. The first one found is used. If none are found, the module tries	128	found is used. If none are detected, the module tries to load the first
98	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	129	four modules in the order given; but note that if L<EV> is not
99	adaptor should always succeed) in the order given. The first one that can	130	available, the pure-perl L<AnyEvent::Loop> should always work, so
100	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
101	found, AnyEvent will fall back to a pure-perl event loop, which is not
102	very efficient, but should work everywhere.
103		132
104	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
105	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
106	that model the default. For example:	135	that model the default. For example:
107		136
…		…
109	use AnyEvent;	138	use AnyEvent;
110		139
111	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
112		141
113	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
114	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,
115	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
116		146
117	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
118	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
119	explicitly and enjoy the high availability of that event loop :)	149	availability of that event loop :)
120		150
121	=head1 WATCHERS	151	=head1 WATCHERS
122		152
123	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
124	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
…		…
127	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
128	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
129	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
130	is in control).	160	is in control).
131		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
132	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
133	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
134	to it).	170	to it).
135		171
136	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.
137		173
138	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
139	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.
140		176
141	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
142		178
143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
144	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
145	undef $w;	181	undef $w;
146	});	182	});
…		…
149	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
150	declared.	186	declared.
151		187
152	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
153		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
154	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
155	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
156		198
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	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
158	for events. C<poll> must be a string that is either C<r> or C<w>,	206	C<poll> must be a string that is either C<r> or C<w>, which creates a
159	which creates a watcher waiting for "r"eadable or "w"ritable events,	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
160	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.
161	becomes ready.
162		210
163	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
166		214
167	The I/O watcher might use the underlying file descriptor or a copy of it.	215	The I/O watcher might use the underlying file descriptor or a copy of it.
168	You must not close a file handle as long as any watcher is active on the	216	You must not close a file handle as long as any watcher is active on the
169	underlying file descriptor.	217	underlying file descriptor.
170		218
171	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
172	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
173	handles.	221	handles.
174		222
175	Example:
176
177	# 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
178	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	226	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
179	chomp (my $input = <STDIN>);	227	chomp (my $input = <STDIN>);
180	warn "read: $input\n";	228	warn "read: $input\n";
181	undef $w;	229	undef $w;
182	});	230	});
183		231
184	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
185		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
186	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 >>
187	method with the following mandatory arguments:	243	method with the following mandatory arguments:
188		244
189	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
190	supported) the callback should be invoked. C<cb> is the callback to invoke	246	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
192		248
193	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
196		252
197	The timer callback will be invoked at most once: if you want a repeating	253	The callback will normally be invoked only once. If you specify another
198	timer you have to create a new watcher (this is a limitation by both Tk	254	parameter, C<interval>, as a strictly positive number (> 0), then the
199	and Glib).	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.
200		258
201	Example:	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.
202		262
203	# fire an event after 7.7 seconds	263	Example: fire an event after 7.7 seconds.
		264
204	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
205	warn "timeout\n";	266	warn "timeout\n";
206	});	267	});
207		268
208	# to cancel the timer:	269	# to cancel the timer:
209	undef $w;	270	undef $w;
210		271
211	Example 2:
212
213	# 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.
214	my $w;
215		273
216	my $cb = sub {
217	# cancel the old timer while creating a new one
218	$w = AnyEvent->timer (after => 1, cb => $cb);	274	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		275	warn "timeout\n";
219	};	276	};
220
221	# start the "loop" by creating the first watcher
222	$w = AnyEvent->timer (after => 0.5, cb => $cb);
223		277
224	=head3 TIMING ISSUES	278	=head3 TIMING ISSUES
225		279
226	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
227	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
…		…
229		283
230	While most event loops expect timers to specified in a relative way, they	284	While most event loops expect timers to specified in a relative way, they
231	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
232	"jumps", for example, when ntp decides to set your clock backwards from	286	"jumps", for example, when ntp decides to set your clock backwards from
233	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to	287	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
234	fire "after" a second might actually take six years to finally fire.	288	fire "after a second" might actually take six years to finally fire.
235		289
236	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
237	about these issues is L<EV>, which offers both relative (ev_timer, based	291	of these issues is L<EV>, which offers both relative (ev_timer, based
238	on true relative time) and absolute (ev_periodic, based on wallclock time)	292	on true relative time) and absolute (ev_periodic, based on wallclock time)
239	timers.	293	timers.
240		294
241	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
242	AnyEvent API.	296	AnyEvent API.
…		…
264	I<In almost all cases (in all cases if you don't care), this is the	318	I<In almost all cases (in all cases if you don't care), this is the
265	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
266		320
267	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
268	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
269	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
270		324
271	The rest of this section is only of relevance if you try to be very exact	325	The rest of this section is only of relevance if you try to be very exact
272	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
273		327
274	For a practical example of when these times differ, consider L<Event::Lib>	328	For a practical example of when these times differ, consider L<Event::Lib>
275	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
276		330
277	The event loop is running and has just invoked one of your callback at	331	The event loop is running and has just invoked one of your callbacks at
278	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
279	you wait a second by executing C<sleep 1> (blocking the process for a	333	you wait a second by executing C<sleep 1> (blocking the process for a
280	second) and then (at time=501) you create a relative timer that fires	334	second) and then (at time=501) you create a relative timer that fires
281	after three seconds.	335	after three seconds.
282		336
…		…
300	In either case, if you care (and in most cases, you don't), then you	354	In either case, if you care (and in most cases, you don't), then you
301	can get whatever behaviour you want with any event loop, by taking the	355	can get whatever behaviour you want with any event loop, by taking the
302	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
303	account.	357	account.
304		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
305	=back	381	=back
306		382
307	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
308		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		386
309	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
310	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
311	be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
312		390
313	Although the callback might get passed parameters, their value and	391	Although the callback might get passed parameters, their value and
314	presence is undefined and you cannot rely on them. Portable AnyEvent	392	presence is undefined and you cannot rely on them. Portable AnyEvent
315	callbacks cannot use arguments passed to signal watcher callbacks.	393	callbacks cannot use arguments passed to signal watcher callbacks.
316		394
…		…
318	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
319	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,
320	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
321		399
322	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
323	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
324		403
325	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
326	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
327		407
328	Example: exit on SIGINT	408	Example: exit on SIGINT
329		409
330	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
331		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling)
		421	or "unsafe" (asynchronous) - the former might delay signal delivery
		422	indefinitely, the latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support
		432	attaching callbacks to signals in a generic way, which is a pity,
		433	as you cannot do race-free signal handling in perl, requiring
		434	C libraries for this. AnyEvent will try to do its best, which
		435	means in some cases, signals will be delayed. The maximum time
		436	a signal might be delayed is 10 seconds by default, but can
		437	be overriden via C<$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
332	=head2 CHILD PROCESS WATCHERS	447	=head2 CHILD PROCESS WATCHERS
333		448
		449	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		450
334	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.
335		452
336	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,
337	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
338	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
339	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
340	and exit status (as returned by waitpid), so unlike other watcher types,	457	(stopped/continued).
341	you I<can> rely on child watcher callback arguments.	458
		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.
		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).
342		467
343	There is a slight catch to child watchers, however: you usually start them	468	There is a slight catch to child watchers, however: you usually start them
344	I<after> the child process was created, and this means the process could	469	I<after> the child process was created, and this means the process could
345	have exited already (and no SIGCHLD will be sent anymore).	470	have exited already (and no SIGCHLD will be sent anymore).
346		471
347	Not all event models handle this correctly (POE doesn't), but even for	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
348	event models that I<do> handle this correctly, they usually need to be	474	that I<do> handle this correctly, they usually need to be loaded before
349	loaded before the process exits (i.e. before you fork in the first place).	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.
350		478
351	This means you cannot create a child watcher as the very first thing in an	479	This means you cannot create a child watcher as the very first
352	AnyEvent program, you I<have> to create at least one watcher before you	480	thing in an AnyEvent program, you I<have> to create at least one
353	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	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.
354		487
355	Example: fork a process and wait for it	488	Example: fork a process and wait for it
356		489
357	my $done = AnyEvent->condvar;	490	my $done = AnyEvent->condvar;
358		491
…		…
368	);	501	);
369		502
370	# do something else, then wait for process exit	503	# do something else, then wait for process exit
371	$done->recv;	504	$done->recv;
372		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	});
		545
373	=head2 CONDITION VARIABLES	546	=head2 CONDITION VARIABLES
		547
		548	$cv = AnyEvent->condvar;
		549
		550	$cv->send (<list>);
		551	my @res = $cv->recv;
374		552
375	If you are familiar with some event loops you will know that all of them	553	If you are familiar with some event loops you will know that all of them
376	require you to run some blocking "loop", "run" or similar function that	554	require you to run some blocking "loop", "run" or similar function that
377	will actively watch for new events and call your callbacks.	555	will actively watch for new events and call your callbacks.
378		556
379	AnyEvent is different, it expects somebody else to run the event loop and	557	AnyEvent is slightly different: it expects somebody else to run the event
380	will only block when necessary (usually when told by the user).	558	loop and will only block when necessary (usually when told by the user).
381		559
382	The instrument to do that is called a "condition variable", so called	560	The tool to do that is called a "condition variable", so called because
383	because they represent a condition that must become true.	561	they represent a condition that must become true.
		562
		563	Now is probably a good time to look at the examples further below.
384		564
385	Condition variables can be created by calling the C<< AnyEvent->condvar	565	Condition variables can be created by calling the C<< AnyEvent->condvar
386	>> method, usually without arguments. The only argument pair allowed is	566	>> method, usually without arguments. The only argument pair allowed is
387	C<cb>, which specifies a callback to be called when the condition variable	567	C<cb>, which specifies a callback to be called when the condition variable
388	becomes true.	568	becomes true, with the condition variable as the first argument (but not
		569	the results).
389		570
390	After creation, the condition variable is "false" until it becomes "true"	571	After creation, the condition variable is "false" until it becomes "true"
391	by calling the C<send> method (or calling the condition variable as if it	572	by calling the C<send> method (or calling the condition variable as if it
392	were a callback, read about the caveats in the description for the C<<	573	were a callback, read about the caveats in the description for the C<<
393	->send >> method).	574	->send >> method).
394		575
395	Condition variables are similar to callbacks, except that you can	576	Since condition variables are the most complex part of the AnyEvent API, here are
396	optionally wait for them. They can also be called merge points - points	577	some different mental models of what they are - pick the ones you can connect to:
397	in time where multiple outstanding events have been processed. And yet	578
398	another way to call them is transactions - each condition variable can be	579	=over 4
399	used to represent a transaction, which finishes at some point and delivers	580
400	a result.	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
401		599
402	Condition variables are very useful to signal that something has finished,	600	Condition variables are very useful to signal that something has finished,
403	for example, if you write a module that does asynchronous http requests,	601	for example, if you write a module that does asynchronous http requests,
404	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
405	availability of results. The user can either act when the callback is	603	availability of results. The user can either act when the callback is
…		…
418		616
419	Condition variables are represented by hash refs in perl, and the keys	617	Condition variables are represented by hash refs in perl, and the keys
420	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	618	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
421	easy (it is often useful to build your own transaction class on top of	619	easy (it is often useful to build your own transaction class on top of
422	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	620	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
423	it's C<new> method in your own C<new> method.	621	its C<new> method in your own C<new> method.
424		622
425	There are two "sides" to a condition variable - the "producer side" which	623	There are two "sides" to a condition variable - the "producer side" which
426	eventually calls C<< -> send >>, and the "consumer side", which waits	624	eventually calls C<< -> send >>, and the "consumer side", which waits
427	for the send to occur.	625	for the send to occur.
428		626
429	Example: wait for a timer.	627	Example: wait for a timer.
430		628
431	# wait till the result is ready	629	# condition: "wait till the timer is fired"
432	my $result_ready = AnyEvent->condvar;	630	my $timer_fired = AnyEvent->condvar;
433		631
434	# do something such as adding a timer	632	# create the timer - we could wait for, say
435	# or socket watcher the calls $result_ready->send	633	# a handle becomign ready, or even an
436	# when the "result" is ready.	634	# AnyEvent::HTTP request to finish, but
437	# in this case, we simply use a timer:	635	# in this case, we simply use a timer:
438	my $w = AnyEvent->timer (	636	my $w = AnyEvent->timer (
439	after => 1,	637	after => 1,
440	cb => sub { $result_ready->send },	638	cb => sub { $timer_fired->send },
441	);	639	);
442		640
443	# this "blocks" (while handling events) till the callback	641	# this "blocks" (while handling events) till the callback
444	# calls send	642	# calls ->send
445	$result_ready->recv;	643	$timer_fired->recv;
446		644
447	Example: wait for a timer, but take advantage of the fact that	645	Example: wait for a timer, but take advantage of the fact that condition
448	condition variables are also code references.	646	variables are also callable directly.
449		647
450	my $done = AnyEvent->condvar;	648	my $done = AnyEvent->condvar;
451	my $delay = AnyEvent->timer (after => 5, cb => $done);	649	my $delay = AnyEvent->timer (after => 5, cb => $done);
452	$done->recv;	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	});
453		668
454	=head3 METHODS FOR PRODUCERS	669	=head3 METHODS FOR PRODUCERS
455		670
456	These methods should only be used by the producing side, i.e. the	671	These methods should only be used by the producing side, i.e. the
457	code/module that eventually sends the signal. Note that it is also	672	code/module that eventually sends the signal. Note that it is also
…		…
470	immediately from within send.	685	immediately from within send.
471		686
472	Any arguments passed to the C<send> call will be returned by all	687	Any arguments passed to the C<send> call will be returned by all
473	future C<< ->recv >> calls.	688	future C<< ->recv >> calls.
474		689
475	Condition variables are overloaded so one can call them directly	690	Condition variables are overloaded so one can call them directly (as if
476	(as a code reference). Calling them directly is the same as calling	691	they were a code reference). Calling them directly is the same as calling
477	C<send>. Note, however, that many C-based event loops do not handle	692	C<send>.
478	overloading, so as tempting as it may be, passing a condition variable
479	instead of a callback does not work. Both the pure perl and EV loops
480	support overloading, however, as well as all functions that use perl to
481	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
482	example).
483		693
484	=item $cv->croak ($error)	694	=item $cv->croak ($error)
485		695
486	Similar to send, but causes all call's to C<< ->recv >> to invoke	696	Similar to send, but causes all calls to C<< ->recv >> to invoke
487	C<Carp::croak> with the given error message/object/scalar.	697	C<Carp::croak> with the given error message/object/scalar.
488		698
489	This can be used to signal any errors to the condition variable	699	This can be used to signal any errors to the condition variable
490	user/consumer.	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.
491		705
492	=item $cv->begin ([group callback])	706	=item $cv->begin ([group callback])
493		707
494	=item $cv->end	708	=item $cv->end
495
496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
497		709
498	These two methods can be used to combine many transactions/events into	710	These two methods can be used to combine many transactions/events into
499	one. For example, a function that pings many hosts in parallel might want	711	one. For example, a function that pings many hosts in parallel might want
500	to use a condition variable for the whole process.	712	to use a condition variable for the whole process.
501		713
502	Every call to C<< ->begin >> will increment a counter, and every call to	714	Every call to C<< ->begin >> will increment a counter, and every call to
503	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	715	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
504	>>, the (last) callback passed to C<begin> will be executed. That callback	716	>>, the (last) callback passed to C<begin> will be executed, passing the
505	is I<supposed> to call C<< ->send >>, but that is not required. If no	717	condvar as first argument. That callback is I<supposed> to call C<< ->send
506	callback was set, C<send> will be called without any arguments.	718	>>, but that is not required. If no group callback was set, C<send> will
		719	be called without any arguments.
507		720
508	Let's clarify this with the ping example:	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:
509		728
510	my $cv = AnyEvent->condvar;	729	my $cv = AnyEvent->condvar;
511		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
512	my %result;	755	my %result;
513	$cv->begin (sub { $cv->send (\%result) });	756	$cv->begin (sub { shift->send (\%result) });
514		757
515	for my $host (@list_of_hosts) {	758	for my $host (@list_of_hosts) {
516	$cv->begin;	759	$cv->begin;
517	ping_host_then_call_callback $host, sub {	760	ping_host_then_call_callback $host, sub {
518	$result{$host} = ...;	761	$result{$host} = ...;
…		…
533	loop, which serves two important purposes: first, it sets the callback	776	loop, which serves two important purposes: first, it sets the callback
534	to be called once the counter reaches C<0>, and second, it ensures that	777	to be called once the counter reaches C<0>, and second, it ensures that
535	C<send> is called even when C<no> hosts are being pinged (the loop	778	C<send> is called even when C<no> hosts are being pinged (the loop
536	doesn't execute once).	779	doesn't execute once).
537		780
538	This is the general pattern when you "fan out" into multiple subrequests:	781	This is the general pattern when you "fan out" into multiple (but
539	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	782	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
540	is called at least once, and then, for each subrequest you start, call	783	the callback and ensure C<end> is called at least once, and then, for each
541	C<begin> and for each subrequest you finish, call C<end>.	784	subrequest you start, call C<begin> and for each subrequest you finish,
		785	call C<end>.
542		786
543	=back	787	=back
544		788
545	=head3 METHODS FOR CONSUMERS	789	=head3 METHODS FOR CONSUMERS
546		790
…		…
550	=over 4	794	=over 4
551		795
552	=item $cv->recv	796	=item $cv->recv
553		797
554	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	798	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
555	>> methods have been called on c<$cv>, while servicing other watchers	799	>> methods have been called on C<$cv>, while servicing other watchers
556	normally.	800	normally.
557		801
558	You can only wait once on a condition - additional calls are valid but	802	You can only wait once on a condition - additional calls are valid but
559	will return immediately.	803	will return immediately.
560		804
…		…
562	function will call C<croak>.	806	function will call C<croak>.
563		807
564	In list context, all parameters passed to C<send> will be returned,	808	In list context, all parameters passed to C<send> will be returned,
565	in scalar context only the first one will be returned.	809	in scalar context only the first one will be returned.
566		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.
		817
567	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
568	(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
569	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
570	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
571	condition variables with some kind of request results and supporting	822	condition variables with some kind of request results and supporting
572	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,
573	while still supporting blocking waits if the caller so desires).	824	while still supporting blocking waits if the caller so desires).
574		825
575	Another reason I<never> to C<< ->recv >> in a module is that you cannot
576	sensibly have two C<< ->recv >>'s in parallel, as that would require
577	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
578	can supply.
579
580	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
581	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
582	versions and also integrates coroutines into AnyEvent, making blocking
583	C<< ->recv >> calls perfectly safe as long as they are done from another
584	coroutine (one that doesn't run the event loop).
585
586	You can ensure that C<< -recv >> never blocks by setting a callback and	826	You can ensure that C<< ->recv >> never blocks by setting a callback and
587	only calling C<< ->recv >> from within that callback (or at a later	827	only calling C<< ->recv >> from within that callback (or at a later
588	time). This will work even when the event loop does not support blocking	828	time). This will work even when the event loop does not support blocking
589	waits otherwise.	829	waits otherwise.
590		830
591	=item $bool = $cv->ready	831	=item $bool = $cv->ready
592		832
593	Returns true when the condition is "true", i.e. whether C<send> or	833	Returns true when the condition is "true", i.e. whether C<send> or
594	C<croak> have been called.	834	C<croak> have been called.
595		835
596	=item $cb = $cv->cb ([new callback])	836	=item $cb = $cv->cb ($cb->($cv))
597		837
598	This is a mutator function that returns the callback set and optionally	838	This is a mutator function that returns the callback set and optionally
599	replaces it before doing so.	839	replaces it before doing so.
600		840
601	The callback will be called when the condition becomes "true", i.e. when	841	The callback will be called when the condition becomes "true", i.e. when
602	C<send> or C<croak> are called, with the only argument being the condition	842	C<send> or C<croak> are called, with the only argument being the
603	variable itself. Calling C<recv> inside the callback or at any later time	843	condition variable itself. If the condition is already true, the
604	is guaranteed not to block.	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.
605		846
606	=back	847	=back
607		848
		849	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		850
		851	The available backend classes are (every class has its own manpage):
		852
		853	=over 4
		854
		855	=item Backends that are autoprobed when no other event loop can be found.
		856
		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
		911
608	=head1 GLOBAL VARIABLES AND FUNCTIONS	912	=head1 GLOBAL VARIABLES AND FUNCTIONS
609		913
		914	These are not normally required to use AnyEvent, but can be useful to
		915	write AnyEvent extension modules.
		916
610	=over 4	917	=over 4
611		918
612	=item $AnyEvent::MODEL	919	=item $AnyEvent::MODEL
613		920
614	Contains C<undef> until the first watcher is being created. Then it	921	Contains C<undef> until the first watcher is being created, before the
		922	backend has been autodetected.
		923
615	contains the event model that is being used, which is the name of the	924	Afterwards it contains the event model that is being used, which is the
616	Perl class implementing the model. This class is usually one of the	925	name of the Perl class implementing the model. This class is usually one
617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	926	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	927	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
619		928	will be C<urxvt::anyevent>).
620	The known classes so far are:
621
622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
623	AnyEvent::Impl::Event based on Event, second best choice.
624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
625	AnyEvent::Impl::Glib based on Glib, third-best choice.
626	AnyEvent::Impl::Tk based on Tk, very bad choice.
627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
629	AnyEvent::Impl::POE based on POE, not generic enough for full support.
630
631	There is no support for WxWidgets, as WxWidgets has no support for
632	watching file handles. However, you can use WxWidgets through the
633	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
634	second, which was considered to be too horrible to even consider for
635	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
636	it's adaptor.
637
638	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
639	autodetecting them.
640		929
641	=item AnyEvent::detect	930	=item AnyEvent::detect
642		931
643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	932	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
644	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
645	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
646	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>.
647		943
648	=item $guard = AnyEvent::post_detect { BLOCK }	944	=item $guard = AnyEvent::post_detect { BLOCK }
649		945
650	Arranges for the code block to be executed as soon as the event model is	946	Arranges for the code block to be executed as soon as the event model is
651	autodetected (or immediately if this has already happened).	947	autodetected (or immediately if that has already happened).
		948
		949	The block will be executed I<after> the actual backend has been detected
		950	(C<$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.
652		959
653	If called in scalar or list context, then it creates and returns an object	960	If called in scalar or list context, then it creates and returns an object
654	that automatically removes the callback again when it is destroyed. See	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
655	L<Coro::BDB> for a case where this is useful.	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 ||= $guard;
656		980
657	=item @AnyEvent::post_detect	981	=item @AnyEvent::post_detect
658		982
659	If there are any code references in this array (you can C<push> to it	983	If there are any code references in this array (you can C<push> to it
660	before or after loading AnyEvent), then they will called directly after	984	before or after loading AnyEvent), then they will be called directly
661	the event loop has been chosen.	985	after the event loop has been chosen.
662		986
663	You should check C<$AnyEvent::MODEL> before adding to this array, though:	987	You should check C<$AnyEvent::MODEL> before adding to this array, though:
664	if it contains a true value then the event loop has already been detected,	988	if it is defined then the event loop has already been detected, and the
665	and the array will be ignored.	989	array will be ignored.
666		990
667	Best use C<AnyEvent::post_detect { BLOCK }> instead.	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.
668		1069
669	=back	1070	=back
670		1071
671	=head1 WHAT TO DO IN A MODULE	1072	=head1 WHAT TO DO IN A MODULE
672		1073
…		…
683	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
684	events is to stay interactive.	1085	events is to stay interactive.
685		1086
686	It is fine, however, to call C<< ->recv >> when the user of your module	1087	It is fine, however, to call C<< ->recv >> when the user of your module
687	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
688	called C<results> that returns the results, it should call C<< ->recv >>	1089	called C<results> that returns the results, it may call C<< ->recv >>
689	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).
690		1091
691	=head1 WHAT TO DO IN THE MAIN PROGRAM	1092	=head1 WHAT TO DO IN THE MAIN PROGRAM
692		1093
693	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
694	dictate which event model to use.	1095	dictate which event model to use.
695		1096
696	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
697	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
698	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.
699		1102
700	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
701	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
702	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
703	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
704	modules might create watchers when they are loaded, and AnyEvent will	1107	modules might create watchers when they are loaded, and AnyEvent will
705	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
706	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.
707		1110
708	You can chose to use a pure-perl implementation by loading the	1111	You can chose to use a pure-perl implementation by loading the
709	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1112	C<AnyEvent::Loop> module, which gives you similar behaviour
710	everywhere, but letting AnyEvent chose the model is generally better.	1113	everywhere, but letting AnyEvent chose the model is generally better.
711		1114
712	=head2 MAINLOOP EMULATION	1115	=head2 MAINLOOP EMULATION
713		1116
714	Sometimes (often for short test scripts, or even standalone programs who	1117	Sometimes (often for short test scripts, or even standalone programs who
…		…
727		1130
728		1131
729	=head1 OTHER MODULES	1132	=head1 OTHER MODULES
730		1133
731	The following is a non-exhaustive list of additional modules that use	1134	The following is a non-exhaustive list of additional modules that use
732	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1135	AnyEvent as a client and can therefore be mixed easily with other
733	in the same program. Some of the modules come with AnyEvent, some are	1136	AnyEvent modules and other event loops in the same program. Some of the
734	available via CPAN.	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 :)
735		1141
736	=over 4	1142	=over 4
737		1143
738	=item L<AnyEvent::Util>	1144	=item L<AnyEvent::Util>
739		1145
740	Contains various utility functions that replace often-used but blocking	1146	Contains various utility functions that replace often-used blocking
741	functions such as C<inet_aton> by event-/callback-based versions.	1147	functions such as C<inet_aton> with event/callback-based versions.
742
743	=item L<AnyEvent::Handle>
744
745	Provide read and write buffers and manages watchers for reads and writes.
746		1148
747	=item L<AnyEvent::Socket>	1149	=item L<AnyEvent::Socket>
748		1150
749	Provides various utility functions for (internet protocol) sockets,	1151	Provides various utility functions for (internet protocol) sockets,
750	addresses and name resolution. Also functions to create non-blocking tcp	1152	addresses and name resolution. Also functions to create non-blocking tcp
751	connections or tcp servers, with IPv6 and SRV record support and more.	1153	connections or tcp servers, with IPv6 and SRV record support and more.
752		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
753	=item L<AnyEvent::DNS>	1161	=item L<AnyEvent::DNS>
754		1162
755	Provides rich asynchronous DNS resolver capabilities.	1163	Provides rich asynchronous DNS resolver capabilities.
756		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
757	=item L<AnyEvent::HTTP>	1171	=item L<AnyEvent::AIO>
758		1172
759	A simple-to-use HTTP library that is capable of making a lot of concurrent	1173	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
760	HTTP requests.	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.
761		1195
762	=item L<AnyEvent::HTTPD>	1196	=item L<AnyEvent::HTTPD>
763		1197
764	Provides a simple web application server framework.	1198	A simple embedded webserver.
765		1199
766	=item L<AnyEvent::FastPing>	1200	=item L<AnyEvent::FastPing>
767		1201
768	The fastest ping in the west.	1202	The fastest ping in the west.
769		1203
770	=item L<Net::IRC3>
771
772	AnyEvent based IRC client module family.
773
774	=item L<Net::XMPP2>
775
776	AnyEvent based XMPP (Jabber protocol) module family.
777
778	=item L<Net::FCP>
779
780	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
781	of AnyEvent.
782
783	=item L<Event::ExecFlow>
784
785	High level API for event-based execution flow control.
786
787	=item L<Coro>	1204	=item L<Coro>
788		1205
789	Has special support for AnyEvent via L<Coro::AnyEvent>.	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:
790		1208
791	=item L<AnyEvent::AIO>, L<IO::AIO>	1209	async {
		1210	Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
		1211	print "5 seconds later!\n";
792		1212
793	Truly asynchronous I/O, should be in the toolbox of every event	1213	Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
794	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent	1214	my $line = <STDIN>; # works for ttys
795	together.
796		1215
797	=item L<AnyEvent::BDB>, L<BDB>	1216	AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
798		1217	my ($body, $hdr) = Coro::rouse_wait;
799	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses	1218	};
800	IO::AIO and AnyEvent together.
801
802	=item L<IO::Lambda>
803
804	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
805		1219
806	=back	1220	=back
807		1221
808	=cut	1222	=cut
809		1223
810	package AnyEvent;	1224	package AnyEvent;
811		1225
812	no warnings;	1226	# basically a tuned-down version of common::sense
813	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	}
814		1233
		1234	BEGIN { AnyEvent::common_sense }
		1235
815	use Carp;	1236	use Carp ();
816		1237
817	our $VERSION = 4.14;	1238	our $VERSION = '6.02';
818	our $MODEL;	1239	our $MODEL;
819
820	our $AUTOLOAD;
821	our @ISA;	1240	our @ISA;
822
823	our @REGISTRY;	1241	our @REGISTRY;
824		1242	our $VERBOSE;
825	our $WIN32;	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!)
826		1245
827	BEGIN {	1246	BEGIN {
828	my $win32 = ! ! ($^O =~ /mswin32/i);	1247	require "AnyEvent/constants.pl";
829	eval "sub WIN32(){ $win32 }";
830	}
831		1248
832	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1249	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
833		1250
834	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1251	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1252	if ${^TAINT};
835		1253
836	{	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
837	my $idx;	1264	my $idx;
838	$PROTOCOL{$_} = ++$idx	1265	$PROTOCOL{$_} = ++$idx
839	for reverse split /\s*,\s*/,	1266	for reverse split /\s*,\s*/,
840	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1267	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
841	}	1268	}
842		1269
		1270	our @post_detect;
		1271
		1272	sub post_detect(&) {
		1273	my ($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($$;@) {
		1305	# only load the big bloated module when we actually are about to log something
		1306	if ($_[0] <= ($VERBOSE || 1)) { # also catches non-numeric levels(!) and fatal
		1307	local ($!, $@);
		1308	require AnyEvent::Log; # among other things, sets $VERBOSE to 9
		1309	# AnyEvent::Log overwrites this function
		1310	goto &log;
		1311	}
		1312
		1313	0 # not logged
		1314	}
		1315
		1316	sub _logger($;$) {
		1317	my ($level, $renabled) = @_;
		1318
		1319	$$renabled = $level <= $VERBOSE;
		1320
		1321	my $logger = [(caller)[0], $level, $renabled];
		1322
		1323	$AnyEvent::Log::LOGGER{$logger+0} = $logger;
		1324
		1325	# return unless defined wantarray;
		1326	#
		1327	# require AnyEvent::Util;
		1328	# my $guard = AnyEvent::Util::guard (sub {
		1329	# # "clean up"
		1330	# delete $LOGGER{$logger+0};
		1331	# });
		1332	#
		1333	# sub {
		1334	# return 0 unless $$renabled;
		1335	#
		1336	# $guard if 0; # keep guard alive, but don't cause runtime overhead
		1337	# require AnyEvent::Log unless $AnyEvent::Log::VERSION;
		1338	# package AnyEvent::Log;
		1339	# _log ($logger->[0], $level, @_) # logger->[0] has been converted at load time
		1340	# }
		1341	}
		1342
		1343	if (length $ENV{PERL_ANYEVENT_LOG}) {
		1344	require AnyEvent::Log; # AnyEvent::Log does the thing for us
		1345	}
		1346
843	my @models = (	1347	our @models = (
844	[EV:: => AnyEvent::Impl::EV::],	1348	[EV:: => AnyEvent::Impl::EV::],
845	[Event:: => AnyEvent::Impl::Event::],
846	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1349	[AnyEvent::Loop:: => AnyEvent::Impl::Perl::],
847	# everything below here will not be autoprobed	1350	# everything below here will not (normally) be autoprobed
848	# as the pureperl backend should work everywhere	1351	# as the pure perl backend should work everywhere
849	# and is usually faster	1352	# and is usually faster
		1353	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package, so msut be near the top
		1354	[Event:: => AnyEvent::Impl::Event::], # slow, stable
		1355	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1356	# everything below here should not be autoloaded
		1357	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
850	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1358	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
851	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
852	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
853	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1359	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
854	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1360	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
855	[Wx:: => AnyEvent::Impl::POE::],	1361	[Wx:: => AnyEvent::Impl::POE::],
856	[Prima:: => AnyEvent::Impl::POE::],	1362	[Prima:: => AnyEvent::Impl::POE::],
		1363	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1364	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1365	[FLTK:: => AnyEvent::Impl::FLTK::],
857	);	1366	);
858		1367
859	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1368	our @isa_hook;
860		1369
861	our @post_detect;	1370	sub _isa_set {
		1371	my @pkg = ("AnyEvent", (map $_->[0], grep defined, @isa_hook), $MODEL);
862		1372
		1373	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1374	for 1 .. $#pkg;
		1375
		1376	grep $_ && $_->[1], @isa_hook
		1377	and AE::_reset ();
		1378	}
		1379
		1380	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1381	sub _isa_hook($$;$) {
		1382	my ($i, $pkg, $reset_ae) = @_;
		1383
		1384	$isa_hook[$i] = $pkg ? [$pkg, $reset_ae] : undef;
		1385
		1386	_isa_set;
		1387	}
		1388
		1389	# all autoloaded methods reserve the complete glob, not just the method slot.
		1390	# due to bugs in perls method cache implementation.
		1391	our @methods = qw(io timer time now now_update signal child idle condvar);
		1392
863	sub post_detect(&) {	1393	sub detect() {
864	my ($cb) = @_;	1394	return $MODEL if $MODEL; # some programs keep references to detect
865		1395
866	if ($MODEL) {	1396	# IO::Async::Loop::AnyEvent is extremely evil, refuse to work with it
867	$cb->();	1397	# the author knows about the problems and what it does to AnyEvent as a whole
		1398	# (and the ability of others to use AnyEvent), but simply wants to abuse AnyEvent
		1399	# anyway.
		1400	AnyEvent::log fatal => "AnyEvent: IO::Async::Loop::AnyEvent detected - this module is broken by design,\n"
		1401	. "abuses internals and breaks AnyEvent, will not continue."
		1402	if exists $INC{"IO/Async/Loop/AnyEvent.pm"};
868		1403
869	1	1404	local $!; # for good measure
		1405	local $SIG{__DIE__}; # we use eval
		1406
		1407	# free some memory
		1408	*detect = sub () { $MODEL };
		1409	# undef &func doesn't correctly update the method cache. grmbl.
		1410	# so we delete the whole glob. grmbl.
		1411	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1412	# a glob with an active sub. hrm. i hope it works, but perl is
		1413	# usually buggy in this department. sigh.
		1414	delete @{"AnyEvent::"}{@methods};
		1415	undef @methods;
		1416
		1417	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1418	my $model = $1;
		1419	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1420	if (eval "require $model") {
		1421	AnyEvent::log 7 => "loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.";
		1422	$MODEL = $model;
870	} else {	1423	} else {
871	push @post_detect, $cb;	1424	AnyEvent::log 4 => "unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
872		1425	}
873	defined wantarray
874	? bless \$cb, "AnyEvent::Util::PostDetect"
875	: ()
876	}	1426	}
877	}
878		1427
879	sub AnyEvent::Util::PostDetect::DESTROY {	1428	# check for already loaded models
880	@post_detect = grep $_ != ${$_[0]}, @post_detect;
881	}
882
883	sub detect() {
884	unless ($MODEL) {	1429	unless ($MODEL) {
885	no strict 'refs';	1430	for (@REGISTRY, @models) {
886	local $SIG{__DIE__};	1431	my ($package, $model) = @$_;
887		1432	if (${"$package\::VERSION"} > 0) {
888	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
889	my $model = "AnyEvent::Impl::$1";
890	if (eval "require $model") {	1433	if (eval "require $model") {
		1434	AnyEvent::log 7 => "autodetected model '$model', using it.";
891	$MODEL = $model;	1435	$MODEL = $model;
892	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1436	last;
893	} else {	1437	}
894	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;
895	}	1438	}
896	}	1439	}
897		1440
898	# check for already loaded models
899	unless ($MODEL) {	1441	unless ($MODEL) {
		1442	# try to autoload a model
900	for (@REGISTRY, @models) {	1443	for (@REGISTRY, @models) {
901	my ($package, $model) = @$_;	1444	my ($package, $model) = @$_;
		1445	if (
		1446	eval "require $package"
902	if (${"$package\::VERSION"} > 0) {	1447	and ${"$package\::VERSION"} > 0
903	if (eval "require $model") {	1448	and eval "require $model"
		1449	) {
		1450	AnyEvent::log 7 => "autoloaded model '$model', using it.";
904	$MODEL = $model;	1451	$MODEL = $model;
905	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
906	last;	1452	last;
907	}
908	}	1453	}
909	}	1454	}
910		1455
911	unless ($MODEL) {	1456	$MODEL
912	# try to load a model	1457	or AnyEvent::log fatal => "AnyEvent: backend autodetection failed - did you properly install AnyEvent?";
		1458	}
		1459	}
913		1460
914	for (@REGISTRY, @models) {	1461	# free memory only needed for probing
915	my ($package, $model) = @$_;	1462	undef @models;
916	if (eval "require $package"	1463	undef @REGISTRY;
917	and ${"$package\::VERSION"} > 0	1464
918	and eval "require $model") {	1465	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
919	$MODEL = $model;	1466
920	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1467	# now nuke some methods that are overridden by the backend.
		1468	# SUPER usage is not allowed in these.
		1469	for (qw(time signal child idle)) {
		1470	undef &{"AnyEvent::Base::$_"}
		1471	if defined &{"$MODEL\::$_"};
		1472	}
		1473
		1474	_isa_set;
		1475
		1476	# we're officially open!
		1477
		1478	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1479	require AnyEvent::Strict;
		1480	}
		1481
		1482	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1483	require AnyEvent::Debug;
		1484	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1485	}
		1486
		1487	if (length $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1488	require AnyEvent::Socket;
		1489	require AnyEvent::Debug;
		1490
		1491	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1492	$shell =~ s/\$\$/$$/g;
		1493
		1494	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1495	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1496	}
		1497
		1498	# now the anyevent environment is set up as the user told us to, so
		1499	# call the actual user code - post detects
		1500
		1501	(shift @post_detect)->() while @post_detect;
		1502	undef @post_detect;
		1503
		1504	*post_detect = sub(&) {
		1505	shift->();
		1506
		1507	undef
		1508	};
		1509
		1510	$MODEL
		1511	}
		1512
		1513	for my $name (@methods) {
		1514	*$name = sub {
		1515	detect;
		1516	# we use goto because
		1517	# a) it makes the thunk more transparent
		1518	# b) it allows us to delete the thunk later
		1519	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
		1520	};
		1521	}
		1522
		1523	# utility function to dup a filehandle. this is used by many backends
		1524	# to support binding more than one watcher per filehandle (they usually
		1525	# allow only one watcher per fd, so we dup it to get a different one).
		1526	sub _dupfh($$;$$) {
		1527	my ($poll, $fh, $r, $w) = @_;
		1528
		1529	# cygwin requires the fh mode to be matching, unix doesn't
		1530	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1531
		1532	open my $fh2, $mode, $fh
		1533	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1534
		1535	# we assume CLOEXEC is already set by perl in all important cases
		1536
		1537	($fh2, $rw)
		1538	}
		1539
		1540	=head1 SIMPLIFIED AE API
		1541
		1542	Starting with version 5.0, AnyEvent officially supports a second, much
		1543	simpler, API that is designed to reduce the calling, typing and memory
		1544	overhead by using function call syntax and a fixed number of parameters.
		1545
		1546	See the L<AE> manpage for details.
		1547
		1548	=cut
		1549
		1550	package AE;
		1551
		1552	our $VERSION = $AnyEvent::VERSION;
		1553
		1554	sub _reset() {
		1555	eval q{
		1556	# fall back to the main API by default - backends and AnyEvent::Base
		1557	# implementations can overwrite these.
		1558
		1559	sub io($$$) {
		1560	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1561	}
		1562
		1563	sub timer($$$) {
		1564	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1565	}
		1566
		1567	sub signal($$) {
		1568	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1569	}
		1570
		1571	sub child($$) {
		1572	AnyEvent->child (pid => $_[0], cb => $_[1])
		1573	}
		1574
		1575	sub idle($) {
		1576	AnyEvent->idle (cb => $_[0]);
		1577	}
		1578
		1579	sub cv(;&) {
		1580	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1581	}
		1582
		1583	sub now() {
		1584	AnyEvent->now
		1585	}
		1586
		1587	sub now_update() {
		1588	AnyEvent->now_update
		1589	}
		1590
		1591	sub time() {
		1592	AnyEvent->time
		1593	}
		1594
		1595	*postpone = \&AnyEvent::postpone;
		1596	*log = \&AnyEvent::log;
		1597	};
		1598	die if $@;
		1599	}
		1600
		1601	BEGIN { _reset }
		1602
		1603	package AnyEvent::Base;
		1604
		1605	# default implementations for many methods
		1606
		1607	sub time {
		1608	eval q{ # poor man's autoloading {}
		1609	# probe for availability of Time::HiRes
		1610	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1611	*time = sub { Time::HiRes::time () };
		1612	*AE::time = \& Time::HiRes::time ;
		1613	*now = \&time;
		1614	AnyEvent::log 8 => "AnyEvent: using Time::HiRes for sub-second timing accuracy.";
		1615	# if (eval "use POSIX (); (POSIX::times())...
		1616	} else {
		1617	*time = sub { CORE::time };
		1618	*AE::time = sub (){ CORE::time };
		1619	*now = \&time;
		1620	AnyEvent::log 3 => "using built-in time(), WARNING, no sub-second resolution!";
		1621	}
		1622	};
		1623	die if $@;
		1624
		1625	&time
		1626	}
		1627
		1628	*now = \&time;
		1629	sub now_update { }
		1630
		1631	sub _poll {
		1632	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1633	}
		1634
		1635	# default implementation for ->condvar
		1636	# in fact, the default should not be overwritten
		1637
		1638	sub condvar {
		1639	eval q{ # poor man's autoloading {}
		1640	*condvar = sub {
		1641	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1642	};
		1643
		1644	*AE::cv = sub (;&) {
		1645	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1646	};
		1647	};
		1648	die if $@;
		1649
		1650	&condvar
		1651	}
		1652
		1653	# default implementation for ->signal
		1654
		1655	our $HAVE_ASYNC_INTERRUPT;
		1656
		1657	sub _have_async_interrupt() {
		1658	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1659	&& eval "use Async::Interrupt 1.02 (); 1")
		1660	unless defined $HAVE_ASYNC_INTERRUPT;
		1661
		1662	$HAVE_ASYNC_INTERRUPT
		1663	}
		1664
		1665	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1666	our (%SIG_ASY, %SIG_ASY_W);
		1667	our ($SIG_COUNT, $SIG_TW);
		1668
		1669	# install a dummy wakeup watcher to reduce signal catching latency
		1670	# used by Impls
		1671	sub _sig_add() {
		1672	unless ($SIG_COUNT++) {
		1673	# try to align timer on a full-second boundary, if possible
		1674	my $NOW = AE::now;
		1675
		1676	$SIG_TW = AE::timer
		1677	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1678	$MAX_SIGNAL_LATENCY,
		1679	sub { } # just for the PERL_ASYNC_CHECK
		1680	;
		1681	}
		1682	}
		1683
		1684	sub _sig_del {
		1685	undef $SIG_TW
		1686	unless --$SIG_COUNT;
		1687	}
		1688
		1689	our $_sig_name_init; $_sig_name_init = sub {
		1690	eval q{ # poor man's autoloading {}
		1691	undef $_sig_name_init;
		1692
		1693	if (_have_async_interrupt) {
		1694	*sig2num = \&Async::Interrupt::sig2num;
		1695	*sig2name = \&Async::Interrupt::sig2name;
		1696	} else {
		1697	require Config;
		1698
		1699	my %signame2num;
		1700	@signame2num{ split ' ', $Config::Config{sig_name} }
		1701	= split ' ', $Config::Config{sig_num};
		1702
		1703	my @signum2name;
		1704	@signum2name[values %signame2num] = keys %signame2num;
		1705
		1706	*sig2num = sub($) {
		1707	$_[0] > 0 ? shift : $signame2num{+shift}
		1708	};
		1709	*sig2name = sub ($) {
		1710	$_[0] > 0 ? $signum2name[+shift] : shift
		1711	};
		1712	}
		1713	};
		1714	die if $@;
		1715	};
		1716
		1717	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1718	sub sig2name($) { &$_sig_name_init; &sig2name }
		1719
		1720	sub signal {
		1721	eval q{ # poor man's autoloading {}
		1722	# probe for availability of Async::Interrupt
		1723	if (_have_async_interrupt) {
		1724	AnyEvent::log 8 => "using Async::Interrupt for race-free signal handling.";
		1725
		1726	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1727	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1728
		1729	} else {
		1730	AnyEvent::log 8 => "using emulated perl signal handling with latency timer.";
		1731
		1732	if (AnyEvent::WIN32) {
		1733	require AnyEvent::Util;
		1734
		1735	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1736	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1737	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1738	} else {
		1739	pipe $SIGPIPE_R, $SIGPIPE_W;
		1740	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1741	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1742
		1743	# not strictly required, as $^F is normally 2, but let's make sure...
		1744	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1745	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1746	}
		1747
		1748	$SIGPIPE_R
		1749	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1750
		1751	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1752	}
		1753
		1754	*signal = $HAVE_ASYNC_INTERRUPT
		1755	? sub {
		1756	my (undef, %arg) = @_;
		1757
		1758	# async::interrupt
		1759	my $signal = sig2num $arg{signal};
		1760	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1761
		1762	$SIG_ASY{$signal} ||= new Async::Interrupt
		1763	cb => sub { undef $SIG_EV{$signal} },
		1764	signal => $signal,
		1765	pipe => [$SIGPIPE_R->filenos],
		1766	pipe_autodrain => 0,
		1767	;
		1768
		1769	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1770	}
		1771	: sub {
		1772	my (undef, %arg) = @_;
		1773
		1774	# pure perl
		1775	my $signal = sig2name $arg{signal};
		1776	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1777
		1778	$SIG{$signal} ||= sub {
921	last;	1779	local $!;
		1780	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1781	undef $SIG_EV{$signal};
922	}	1782	};
		1783
		1784	# can't do signal processing without introducing races in pure perl,
		1785	# so limit the signal latency.
		1786	_sig_add;
		1787
		1788	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1789	}
		1790	;
		1791
		1792	*AnyEvent::Base::signal::DESTROY = sub {
		1793	my ($signal, $cb) = @{$_[0]};
		1794
		1795	_sig_del;
		1796
		1797	delete $SIG_CB{$signal}{$cb};
		1798
		1799	$HAVE_ASYNC_INTERRUPT
		1800	? delete $SIG_ASY{$signal}
		1801	: # delete doesn't work with older perls - they then
		1802	# print weird messages, or just unconditionally exit
		1803	# instead of getting the default action.
		1804	undef $SIG{$signal}
		1805	unless keys %{ $SIG_CB{$signal} };
		1806	};
		1807
		1808	*_signal_exec = sub {
		1809	$HAVE_ASYNC_INTERRUPT
		1810	? $SIGPIPE_R->drain
		1811	: sysread $SIGPIPE_R, (my $dummy), 9;
		1812
		1813	while (%SIG_EV) {
		1814	for (keys %SIG_EV) {
		1815	delete $SIG_EV{$_};
		1816	&$_ for values %{ $SIG_CB{$_} || {} };
923	}	1817	}
924
925	$MODEL
926	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
927	}	1818	}
928	}	1819	};
929
930	unshift @ISA, $MODEL;
931	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
932
933	(shift @post_detect)->() while @post_detect;
934	}
935
936	$MODEL
937	}
938
939	sub AUTOLOAD {
940	(my $func = $AUTOLOAD) =~ s/.*://;
941
942	$method{$func}
943	or croak "$func: not a valid method for AnyEvent objects";
944
945	detect unless $MODEL;
946
947	my $class = shift;
948	$class->$func (@_);
949	}
950
951	package AnyEvent::Base;
952
953	# default implementation for now and time
954
955	use Time::HiRes ();
956
957	sub time { Time::HiRes::time }
958	sub now { Time::HiRes::time }
959
960	# default implementation for ->condvar
961
962	sub condvar {
963	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
964	}
965
966	# default implementation for ->signal
967
968	our %SIG_CB;
969
970	sub signal {
971	my (undef, %arg) = @_;
972
973	my $signal = uc $arg{signal}
974	or Carp::croak "required option 'signal' is missing";
975
976	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
977	$SIG{$signal} ||= sub {
978	$_->() for values %{ $SIG_CB{$signal} || {} };
979	};	1820	};
		1821	die if $@;
980		1822
981	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1823	&signal
982	}
983
984	sub AnyEvent::Base::Signal::DESTROY {
985	my ($signal, $cb) = @{$_[0]};
986
987	delete $SIG_CB{$signal}{$cb};
988
989	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
990	}	1824	}
991		1825
992	# default implementation for ->child	1826	# default implementation for ->child
993		1827
994	our %PID_CB;	1828	our %PID_CB;
995	our $CHLD_W;	1829	our $CHLD_W;
996	our $CHLD_DELAY_W;	1830	our $CHLD_DELAY_W;
997	our $PID_IDLE;
998	our $WNOHANG;
999		1831
1000	sub _child_wait {	1832	# used by many Impl's
1001	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1833	sub _emit_childstatus($$) {
		1834	my (undef, $rpid, $rstatus) = @_;
		1835
		1836	$_->($rpid, $rstatus)
1002	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1837	for values %{ $PID_CB{$rpid} || {} },
1003	(values %{ $PID_CB{0} || {} });	1838	values %{ $PID_CB{0} || {} };
1004	}
1005
1006	undef $PID_IDLE;
1007	}
1008
1009	sub _sigchld {
1010	# make sure we deliver these changes "synchronous" with the event loop.
1011	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1012	undef $CHLD_DELAY_W;
1013	&_child_wait;
1014	});
1015	}	1839	}
1016		1840
1017	sub child {	1841	sub child {
		1842	eval q{ # poor man's autoloading {}
		1843	*_sigchld = sub {
		1844	my $pid;
		1845
		1846	AnyEvent->_emit_childstatus ($pid, $?)
		1847	while ($pid = waitpid -1, WNOHANG) > 0;
		1848	};
		1849
		1850	*child = sub {
1018	my (undef, %arg) = @_;	1851	my (undef, %arg) = @_;
1019		1852
1020	defined (my $pid = $arg{pid} + 0)	1853	my $pid = $arg{pid};
1021	or Carp::croak "required option 'pid' is missing";	1854	my $cb = $arg{cb};
1022		1855
1023	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1856	$PID_CB{$pid}{$cb+0} = $cb;
1024		1857
1025	unless ($WNOHANG) {
1026	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1027	}
1028
1029	unless ($CHLD_W) {	1858	unless ($CHLD_W) {
1030	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1859	$CHLD_W = AE::signal CHLD => \&_sigchld;
1031	# child could be a zombie already, so make at least one round	1860	# child could be a zombie already, so make at least one round
1032	&_sigchld;	1861	&_sigchld;
1033	}	1862	}
1034		1863
1035	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1864	bless [$pid, $cb+0], "AnyEvent::Base::child"
1036	}	1865	};
1037		1866
1038	sub AnyEvent::Base::Child::DESTROY {	1867	*AnyEvent::Base::child::DESTROY = sub {
1039	my ($pid, $cb) = @{$_[0]};	1868	my ($pid, $icb) = @{$_[0]};
1040		1869
1041	delete $PID_CB{$pid}{$cb};	1870	delete $PID_CB{$pid}{$icb};
1042	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1871	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1043		1872
1044	undef $CHLD_W unless keys %PID_CB;	1873	undef $CHLD_W unless keys %PID_CB;
		1874	};
		1875	};
		1876	die if $@;
		1877
		1878	&child
		1879	}
		1880
		1881	# idle emulation is done by simply using a timer, regardless
		1882	# of whether the process is idle or not, and not letting
		1883	# the callback use more than 50% of the time.
		1884	sub idle {
		1885	eval q{ # poor man's autoloading {}
		1886	*idle = sub {
		1887	my (undef, %arg) = @_;
		1888
		1889	my ($cb, $w, $rcb) = $arg{cb};
		1890
		1891	$rcb = sub {
		1892	if ($cb) {
		1893	$w = AE::time;
		1894	&$cb;
		1895	$w = AE::time - $w;
		1896
		1897	# never use more then 50% of the time for the idle watcher,
		1898	# within some limits
		1899	$w = 0.0001 if $w < 0.0001;
		1900	$w = 5 if $w > 5;
		1901
		1902	$w = AE::timer $w, 0, $rcb;
		1903	} else {
		1904	# clean up...
		1905	undef $w;
		1906	undef $rcb;
		1907	}
		1908	};
		1909
		1910	$w = AE::timer 0.05, 0, $rcb;
		1911
		1912	bless \\$cb, "AnyEvent::Base::idle"
		1913	};
		1914
		1915	*AnyEvent::Base::idle::DESTROY = sub {
		1916	undef $${$_[0]};
		1917	};
		1918	};
		1919	die if $@;
		1920
		1921	&idle
1045	}	1922	}
1046		1923
1047	package AnyEvent::CondVar;	1924	package AnyEvent::CondVar;
1048		1925
1049	our @ISA = AnyEvent::CondVar::Base::;	1926	our @ISA = AnyEvent::CondVar::Base::;
1050		1927
		1928	# only to be used for subclassing
		1929	sub new {
		1930	my $class = shift;
		1931	bless AnyEvent->condvar (@_), $class
		1932	}
		1933
1051	package AnyEvent::CondVar::Base;	1934	package AnyEvent::CondVar::Base;
1052		1935
1053	use overload	1936	#use overload
1054	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1937	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1055	fallback => 1;	1938	# fallback => 1;
		1939
		1940	# save 300+ kilobytes by dirtily hardcoding overloading
		1941	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1942	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1943	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1944	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1945
		1946	our $WAITING;
1056		1947
1057	sub _send {	1948	sub _send {
1058	# nop	1949	# nop
		1950	}
		1951
		1952	sub _wait {
		1953	AnyEvent->_poll until $_[0]{_ae_sent};
1059	}	1954	}
1060		1955
1061	sub send {	1956	sub send {
1062	my $cv = shift;	1957	my $cv = shift;
1063	$cv->{_ae_sent} = [@_];	1958	$cv->{_ae_sent} = [@_];
…		…
1072		1967
1073	sub ready {	1968	sub ready {
1074	$_[0]{_ae_sent}	1969	$_[0]{_ae_sent}
1075	}	1970	}
1076		1971
1077	sub _wait {
1078	AnyEvent->one_event while !$_[0]{_ae_sent};
1079	}
1080
1081	sub recv {	1972	sub recv {
		1973	unless ($_[0]{_ae_sent}) {
		1974	$WAITING
		1975	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1976
		1977	local $WAITING = 1;
1082	$_[0]->_wait;	1978	$_[0]->_wait;
		1979	}
1083		1980
1084	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1981	$_[0]{_ae_croak}
1085	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1982	and Carp::croak $_[0]{_ae_croak};
		1983
		1984	wantarray
		1985	? @{ $_[0]{_ae_sent} }
		1986	: $_[0]{_ae_sent}[0]
1086	}	1987	}
1087		1988
1088	sub cb {	1989	sub cb {
1089	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1990	my $cv = shift;
		1991
		1992	@_
		1993	and $cv->{_ae_cb} = shift
		1994	and $cv->{_ae_sent}
		1995	and (delete $cv->{_ae_cb})->($cv);
		1996
1090	$_[0]{_ae_cb}	1997	$cv->{_ae_cb}
1091	}	1998	}
1092		1999
1093	sub begin {	2000	sub begin {
1094	++$_[0]{_ae_counter};	2001	++$_[0]{_ae_counter};
1095	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	2002	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1100	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	2007	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1101	}	2008	}
1102		2009
1103	# undocumented/compatibility with pre-3.4	2010	# undocumented/compatibility with pre-3.4
1104	*broadcast = \&send;	2011	*broadcast = \&send;
1105	*wait = \&_wait;	2012	*wait = \&recv;
		2013
		2014	=head1 ERROR AND EXCEPTION HANDLING
		2015
		2016	In general, AnyEvent does not do any error handling - it relies on the
		2017	caller to do that if required. The L<AnyEvent::Strict> module (see also
		2018	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		2019	checking of all AnyEvent methods, however, which is highly useful during
		2020	development.
		2021
		2022	As for exception handling (i.e. runtime errors and exceptions thrown while
		2023	executing a callback), this is not only highly event-loop specific, but
		2024	also not in any way wrapped by this module, as this is the job of the main
		2025	program.
		2026
		2027	The pure perl event loop simply re-throws the exception (usually
		2028	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		2029	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		2030	so on.
		2031
		2032	=head1 ENVIRONMENT VARIABLES
		2033
		2034	AnyEvent supports a number of environment variables that tune the
		2035	runtime behaviour. They are usually evaluated when AnyEvent is
		2036	loaded, initialised, or a submodule that uses them is loaded. Many of
		2037	them also cause AnyEvent to load additional modules - for example,
		2038	C<PERL_ANYEVENT_DEBUG_WRAP> causes the L<AnyEvent::Debug> module to be
		2039	loaded.
		2040
		2041	All the environment variables documented here start with
		2042	C<PERL_ANYEVENT_>, which is what AnyEvent considers its own
		2043	namespace. Other modules are encouraged (but by no means required) to use
		2044	C<PERL_ANYEVENT_SUBMODULE> if they have registered the AnyEvent::Submodule
		2045	namespace on CPAN, for any submodule. For example, L<AnyEvent::HTTP> could
		2046	be expected to use C<PERL_ANYEVENT_HTTP_PROXY> (it should not access env
		2047	variables starting with C<AE_>, see below).
		2048
		2049	All variables can also be set via the C<AE_> prefix, that is, instead
		2050	of setting C<PERL_ANYEVENT_VERBOSE> you can also set C<AE_VERBOSE>. In
		2051	case there is a clash btween anyevent and another program that uses
		2052	C<AE_something> you can set the corresponding C<PERL_ANYEVENT_something>
		2053	variable to the empty string, as those variables take precedence.
		2054
		2055	When AnyEvent is first loaded, it copies all C<AE_xxx> env variables
		2056	to their C<PERL_ANYEVENT_xxx> counterpart unless that variable already
		2057	exists. If taint mode is on, then AnyEvent will remove I<all> environment
		2058	variables starting with C<PERL_ANYEVENT_> from C<%ENV> (or replace them
		2059	with C<undef> or the empty string, if the corresaponding C<AE_> variable
		2060	is set).
		2061
		2062	The exact algorithm is currently:
		2063
		2064	1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
		2065	2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
		2066	3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
		2067
		2068	This ensures that child processes will not see the C<AE_> variables.
		2069
		2070	The following environment variables are currently known to AnyEvent:
		2071
		2072	=over 4
		2073
		2074	=item C<PERL_ANYEVENT_VERBOSE>
		2075
		2076	By default, AnyEvent will only log messages with loglevel C<3>
		2077	(C<critical>) or higher (see L<AnyEvent::Log>). You can set this
		2078	environment variable to a numerical loglevel to make AnyEvent more (or
		2079	less) talkative.
		2080
		2081	If you want to do more than just set the global logging level
		2082	you should have a look at C<PERL_ANYEVENT_LOG>, which allows much more
		2083	complex specifications.
		2084
		2085	When set to C<0> (C<off>), then no messages whatsoever will be logged with
		2086	the default logging settings.
		2087
		2088	When set to C<5> or higher (C<warn>), causes AnyEvent to warn about
		2089	unexpected conditions, such as not being able to load the event model
		2090	specified by C<PERL_ANYEVENT_MODEL>, or a guard callback throwing an
		2091	exception - this is the minimum recommended level.
		2092
		2093	When set to C<7> or higher (info), cause AnyEvent to report which event model it
		2094	chooses.
		2095
		2096	When set to C<8> or higher (debug), then AnyEvent will report extra information on
		2097	which optional modules it loads and how it implements certain features.
		2098
		2099	=item C<PERL_ANYEVENT_LOG>
		2100
		2101	Accepts rather complex logging specifications. For example, you could log
		2102	all C<debug> messages of some module to stderr, warnings and above to
		2103	stderr, and errors and above to syslog, with:
		2104
		2105	PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
		2106
		2107	For the rather extensive details, see L<AnyEvent::Log>.
		2108
		2109	This variable is evaluated when AnyEvent (or L<AnyEvent::Log>) is loaded,
		2110	so will take effect even before AnyEvent has initialised itself.
		2111
		2112	Note that specifying this environment variable causes the L<AnyEvent::Log>
		2113	module to be loaded, while C<PERL_ANYEVENT_VERBOSE> does not, so only
		2114	using the latter saves a few hundred kB of memory until the first message
		2115	is being logged.
		2116
		2117	=item C<PERL_ANYEVENT_STRICT>
		2118
		2119	AnyEvent does not do much argument checking by default, as thorough
		2120	argument checking is very costly. Setting this variable to a true value
		2121	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		2122	check the arguments passed to most method calls. If it finds any problems,
		2123	it will croak.
		2124
		2125	In other words, enables "strict" mode.
		2126
		2127	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
		2128	>>, it is definitely recommended to keep it off in production. Keeping
		2129	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		2130	can be very useful, however.
		2131
		2132	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		2133
		2134	If this env variable is nonempty, then its contents will be interpreted by
		2135	C<AnyEvent::Socket::parse_hostport> and C<AnyEvent::Debug::shell> (after
		2136	replacing every occurance of C<$$> by the process pid). The shell object
		2137	is saved in C<$AnyEvent::Debug::SHELL>.
		2138
		2139	This happens when the first watcher is created.
		2140
		2141	For example, to bind a debug shell on a unix domain socket in
		2142	F<< /tmp/debug<pid>.sock >>, you could use this:
		2143
		2144	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		2145	# connect with e.g.: socat readline /tmp/debug123.sock
		2146
		2147	Or to bind to tcp port 4545 on localhost:
		2148
		2149	PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
		2150	# connect with e.g.: telnet localhost 4545
		2151
		2152	Note that creating sockets in F</tmp> or on localhost is very unsafe on
		2153	multiuser systems.
		2154
		2155	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2156
		2157	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2158	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
		2159
		2160	=item C<PERL_ANYEVENT_MODEL>
		2161
		2162	This can be used to specify the event model to be used by AnyEvent, before
		2163	auto detection and -probing kicks in.
		2164
		2165	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2166	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
		2167	resulting module name is loaded and - if the load was successful - used as
		2168	event model backend. If it fails to load then AnyEvent will proceed with
		2169	auto detection and -probing.
		2170
		2171	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2172	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2173	the end of a string designates a module name and quotes it appropriately).
		2174
		2175	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
		2176	could start your program like this:
		2177
		2178	PERL_ANYEVENT_MODEL=Perl perl ...
		2179
		2180	=item C<PERL_ANYEVENT_PROTOCOLS>
		2181
		2182	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		2183	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		2184	of auto probing).
		2185
		2186	Must be set to a comma-separated list of protocols or address families,
		2187	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		2188	used, and preference will be given to protocols mentioned earlier in the
		2189	list.
		2190
		2191	This variable can effectively be used for denial-of-service attacks
		2192	against local programs (e.g. when setuid), although the impact is likely
		2193	small, as the program has to handle conenction and other failures anyways.
		2194
		2195	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		2196	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		2197	- only support IPv4, never try to resolve or contact IPv6
		2198	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		2199	IPv6, but prefer IPv6 over IPv4.
		2200
		2201	=item C<PERL_ANYEVENT_HOSTS>
		2202
		2203	This variable, if specified, overrides the F</etc/hosts> file used by
		2204	L<AnyEvent::Socket>C<::resolve_sockaddr>, i.e. hosts aliases will be read
		2205	from that file instead.
		2206
		2207	=item C<PERL_ANYEVENT_EDNS0>
		2208
		2209	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension for
		2210	DNS. This extension is generally useful to reduce DNS traffic, especially
		2211	when DNSSEC is involved, but some (broken) firewalls drop such DNS
		2212	packets, which is why it is off by default.
		2213
		2214	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		2215	EDNS0 in its DNS requests.
		2216
		2217	=item C<PERL_ANYEVENT_MAX_FORKS>
		2218
		2219	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		2220	will create in parallel.
		2221
		2222	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2223
		2224	The default value for the C<max_outstanding> parameter for the default DNS
		2225	resolver - this is the maximum number of parallel DNS requests that are
		2226	sent to the DNS server.
		2227
		2228	=item C<PERL_ANYEVENT_MAX_SIGNAL_LATENCY>
		2229
		2230	Perl has inherently racy signal handling (you can basically choose between
		2231	losing signals and memory corruption) - pure perl event loops (including
		2232	C<AnyEvent::Loop>, when C<Async::Interrupt> isn't available) therefore
		2233	have to poll regularly to avoid losing signals.
		2234
		2235	Some event loops are racy, but don't poll regularly, and some event loops
		2236	are written in C but are still racy. For those event loops, AnyEvent
		2237	installs a timer that regularly wakes up the event loop.
		2238
		2239	By default, the interval for this timer is C<10> seconds, but you can
		2240	override this delay with this environment variable (or by setting
		2241	the C<$AnyEvent::MAX_SIGNAL_LATENCY> variable before creating signal
		2242	watchers).
		2243
		2244	Lower values increase CPU (and energy) usage, higher values can introduce
		2245	long delays when reaping children or waiting for signals.
		2246
		2247	The L<AnyEvent::Async> module, if available, will be used to avoid this
		2248	polling (with most event loops).
		2249
		2250	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2251
		2252	The absolute path to a F<resolv.conf>-style file to use instead of
		2253	F</etc/resolv.conf> (or the OS-specific configuration) in the default
		2254	resolver, or the empty string to select the default configuration.
		2255
		2256	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2257
		2258	When neither C<ca_file> nor C<ca_path> was specified during
		2259	L<AnyEvent::TLS> context creation, and either of these environment
		2260	variables are nonempty, they will be used to specify CA certificate
		2261	locations instead of a system-dependent default.
		2262
		2263	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2264
		2265	When these are set to C<1>, then the respective modules are not
		2266	loaded. Mostly good for testing AnyEvent itself.
		2267
		2268	=back
1106		2269
1107	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2270	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1108		2271
1109	This is an advanced topic that you do not normally need to use AnyEvent in	2272	This is an advanced topic that you do not normally need to use AnyEvent in
1110	a module. This section is only of use to event loop authors who want to	2273	a module. This section is only of use to event loop authors who want to
…		…
1144		2307
1145	I<rxvt-unicode> also cheats a bit by not providing blocking access to	2308	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1146	condition variables: code blocking while waiting for a condition will	2309	condition variables: code blocking while waiting for a condition will
1147	C<die>. This still works with most modules/usages, and blocking calls must	2310	C<die>. This still works with most modules/usages, and blocking calls must
1148	not be done in an interactive application, so it makes sense.	2311	not be done in an interactive application, so it makes sense.
1149
1150	=head1 ENVIRONMENT VARIABLES
1151
1152	The following environment variables are used by this module:
1153
1154	=over 4
1155
1156	=item C<PERL_ANYEVENT_VERBOSE>
1157
1158	By default, AnyEvent will be completely silent except in fatal
1159	conditions. You can set this environment variable to make AnyEvent more
1160	talkative.
1161
1162	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1163	conditions, such as not being able to load the event model specified by
1164	C<PERL_ANYEVENT_MODEL>.
1165
1166	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1167	model it chooses.
1168
1169	=item C<PERL_ANYEVENT_MODEL>
1170
1171	This can be used to specify the event model to be used by AnyEvent, before
1172	auto detection and -probing kicks in. It must be a string consisting
1173	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1174	and the resulting module name is loaded and if the load was successful,
1175	used as event model. If it fails to load AnyEvent will proceed with
1176	auto detection and -probing.
1177
1178	This functionality might change in future versions.
1179
1180	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1181	could start your program like this:
1182
1183	PERL_ANYEVENT_MODEL=Perl perl ...
1184
1185	=item C<PERL_ANYEVENT_PROTOCOLS>
1186
1187	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1188	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1189	of auto probing).
1190
1191	Must be set to a comma-separated list of protocols or address families,
1192	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1193	used, and preference will be given to protocols mentioned earlier in the
1194	list.
1195
1196	This variable can effectively be used for denial-of-service attacks
1197	against local programs (e.g. when setuid), although the impact is likely
1198	small, as the program has to handle connection errors already-
1199
1200	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1201	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1202	- only support IPv4, never try to resolve or contact IPv6
1203	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1204	IPv6, but prefer IPv6 over IPv4.
1205
1206	=item C<PERL_ANYEVENT_EDNS0>
1207
1208	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1209	for DNS. This extension is generally useful to reduce DNS traffic, but
1210	some (broken) firewalls drop such DNS packets, which is why it is off by
1211	default.
1212
1213	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1214	EDNS0 in its DNS requests.
1215
1216	=item C<PERL_ANYEVENT_MAX_FORKS>
1217
1218	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1219	will create in parallel.
1220
1221	=back
1222		2312
1223	=head1 EXAMPLE PROGRAM	2313	=head1 EXAMPLE PROGRAM
1224		2314
1225	The following program uses an I/O watcher to read data from STDIN, a timer	2315	The following program uses an I/O watcher to read data from STDIN, a timer
1226	to display a message once per second, and a condition variable to quit the	2316	to display a message once per second, and a condition variable to quit the
…		…
1239	warn "read: $input\n"; # output what has been read	2329	warn "read: $input\n"; # output what has been read
1240	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2330	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1241	},	2331	},
1242	);	2332	);
1243		2333
1244	my $time_watcher; # can only be used once
1245
1246	sub new_timer {
1247	$timer = AnyEvent->timer (after => 1, cb => sub {	2334	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1248	warn "timeout\n"; # print 'timeout' about every second	2335	warn "timeout\n"; # print 'timeout' at most every second
1249	&new_timer; # and restart the time
1250	});	2336	});
1251	}
1252
1253	new_timer; # create first timer
1254		2337
1255	$cv->recv; # wait until user enters /^q/i	2338	$cv->recv; # wait until user enters /^q/i
1256		2339
1257	=head1 REAL-WORLD EXAMPLE	2340	=head1 REAL-WORLD EXAMPLE
1258		2341
…		…
1331		2414
1332	The actual code goes further and collects all errors (C<die>s, exceptions)	2415	The actual code goes further and collects all errors (C<die>s, exceptions)
1333	that occurred during request processing. The C<result> method detects	2416	that occurred during request processing. The C<result> method detects
1334	whether an exception as thrown (it is stored inside the $txn object)	2417	whether an exception as thrown (it is stored inside the $txn object)
1335	and just throws the exception, which means connection errors and other	2418	and just throws the exception, which means connection errors and other
1336	problems get reported tot he code that tries to use the result, not in a	2419	problems get reported to the code that tries to use the result, not in a
1337	random callback.	2420	random callback.
1338		2421
1339	All of this enables the following usage styles:	2422	All of this enables the following usage styles:
1340		2423
1341	1. Blocking:	2424	1. Blocking:
…		…
1389	through AnyEvent. The benchmark creates a lot of timers (with a zero	2472	through AnyEvent. The benchmark creates a lot of timers (with a zero
1390	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2473	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1391	which it is), lets them fire exactly once and destroys them again.	2474	which it is), lets them fire exactly once and destroys them again.
1392		2475
1393	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2476	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1394	distribution.	2477	distribution. It uses the L<AE> interface, which makes a real difference
		2478	for the EV and Perl backends only.
1395		2479
1396	=head3 Explanation of the columns	2480	=head3 Explanation of the columns
1397		2481
1398	I<watcher> is the number of event watchers created/destroyed. Since	2482	I<watcher> is the number of event watchers created/destroyed. Since
1399	different event models feature vastly different performances, each event	2483	different event models feature vastly different performances, each event
…		…
1420	watcher.	2504	watcher.
1421		2505
1422	=head3 Results	2506	=head3 Results
1423		2507
1424	name watchers bytes create invoke destroy comment	2508	name watchers bytes create invoke destroy comment
1425	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2509	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1426	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2510	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1427	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2511	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1428	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2512	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1429	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2513	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1430	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2514	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2515	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2516	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1431	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2517	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1432	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2518	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1433	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2519	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1434	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2520	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1435		2521
1436	=head3 Discussion	2522	=head3 Discussion
1437		2523
1438	The benchmark does I<not> measure scalability of the event loop very	2524	The benchmark does I<not> measure scalability of the event loop very
1439	well. For example, a select-based event loop (such as the pure perl one)	2525	well. For example, a select-based event loop (such as the pure perl one)
…		…
1451	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2537	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1452	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2538	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1453	cycles with POE.	2539	cycles with POE.
1454		2540
1455	C<EV> is the sole leader regarding speed and memory use, which are both	2541	C<EV> is the sole leader regarding speed and memory use, which are both
1456	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2542	maximal/minimal, respectively. When using the L<AE> API there is zero
		2543	overhead (when going through the AnyEvent API create is about 5-6 times
		2544	slower, with other times being equal, so still uses far less memory than
1457	far less memory than any other event loop and is still faster than Event	2545	any other event loop and is still faster than Event natively).
1458	natively.
1459		2546
1460	The pure perl implementation is hit in a few sweet spots (both the	2547	The pure perl implementation is hit in a few sweet spots (both the
1461	constant timeout and the use of a single fd hit optimisations in the perl	2548	constant timeout and the use of a single fd hit optimisations in the perl
1462	interpreter and the backend itself). Nevertheless this shows that it	2549	interpreter and the backend itself). Nevertheless this shows that it
1463	adds very little overhead in itself. Like any select-based backend its	2550	adds very little overhead in itself. Like any select-based backend its
1464	performance becomes really bad with lots of file descriptors (and few of	2551	performance becomes really bad with lots of file descriptors (and few of
1465	them active), of course, but this was not subject of this benchmark.	2552	them active), of course, but this was not subject of this benchmark.
1466		2553
1467	The C<Event> module has a relatively high setup and callback invocation	2554	The C<Event> module has a relatively high setup and callback invocation
1468	cost, but overall scores in on the third place.	2555	cost, but overall scores in on the third place.
		2556
		2557	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2558	when using its pure perl backend.
1469		2559
1470	C<Glib>'s memory usage is quite a bit higher, but it features a	2560	C<Glib>'s memory usage is quite a bit higher, but it features a
1471	faster callback invocation and overall ends up in the same class as	2561	faster callback invocation and overall ends up in the same class as
1472	C<Event>. However, Glib scales extremely badly, doubling the number of	2562	C<Event>. However, Glib scales extremely badly, doubling the number of
1473	watchers increases the processing time by more than a factor of four,	2563	watchers increases the processing time by more than a factor of four,
…		…
1508	(even when used without AnyEvent), but most event loops have acceptable	2598	(even when used without AnyEvent), but most event loops have acceptable
1509	performance with or without AnyEvent.	2599	performance with or without AnyEvent.
1510		2600
1511	=item * The overhead AnyEvent adds is usually much smaller than the overhead of	2601	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
1512	the actual event loop, only with extremely fast event loops such as EV	2602	the actual event loop, only with extremely fast event loops such as EV
1513	adds AnyEvent significant overhead.	2603	does AnyEvent add significant overhead.
1514		2604
1515	=item * You should avoid POE like the plague if you want performance or	2605	=item * You should avoid POE like the plague if you want performance or
1516	reasonable memory usage.	2606	reasonable memory usage.
1517		2607
1518	=back	2608	=back
…		…
1534	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2624	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1535	(1%) are active. This mirrors the activity of large servers with many	2625	(1%) are active. This mirrors the activity of large servers with many
1536	connections, most of which are idle at any one point in time.	2626	connections, most of which are idle at any one point in time.
1537		2627
1538	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2628	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1539	distribution.	2629	distribution. It uses the L<AE> interface, which makes a real difference
		2630	for the EV and Perl backends only.
1540		2631
1541	=head3 Explanation of the columns	2632	=head3 Explanation of the columns
1542		2633
1543	I<sockets> is the number of sockets, and twice the number of "servers" (as	2634	I<sockets> is the number of sockets, and twice the number of "servers" (as
1544	each server has a read and write socket end).	2635	each server has a read and write socket end).
…		…
1551	it to another server. This includes deleting the old timeout and creating	2642	it to another server. This includes deleting the old timeout and creating
1552	a new one that moves the timeout into the future.	2643	a new one that moves the timeout into the future.
1553		2644
1554	=head3 Results	2645	=head3 Results
1555		2646
1556	name sockets create request	2647	name sockets create request
1557	EV 20000 69.01 11.16	2648	EV 20000 62.66 7.99
1558	Perl 20000 73.32 35.87	2649	Perl 20000 68.32 32.64
1559	Event 20000 212.62 257.32	2650	IOAsync 20000 174.06 101.15 epoll
1560	Glib 20000 651.16 1896.30	2651	IOAsync 20000 174.67 610.84 poll
		2652	Event 20000 202.69 242.91
		2653	Glib 20000 557.01 1689.52
1561	POE 20000 349.67 12317.24 uses POE::Loop::Event	2654	POE 20000 341.54 12086.32 uses POE::Loop::Event
1562		2655
1563	=head3 Discussion	2656	=head3 Discussion
1564		2657
1565	This benchmark I<does> measure scalability and overall performance of the	2658	This benchmark I<does> measure scalability and overall performance of the
1566	particular event loop.	2659	particular event loop.
…		…
1568	EV is again fastest. Since it is using epoll on my system, the setup time	2661	EV is again fastest. Since it is using epoll on my system, the setup time
1569	is relatively high, though.	2662	is relatively high, though.
1570		2663
1571	Perl surprisingly comes second. It is much faster than the C-based event	2664	Perl surprisingly comes second. It is much faster than the C-based event
1572	loops Event and Glib.	2665	loops Event and Glib.
		2666
		2667	IO::Async performs very well when using its epoll backend, and still quite
		2668	good compared to Glib when using its pure perl backend.
1573		2669
1574	Event suffers from high setup time as well (look at its code and you will	2670	Event suffers from high setup time as well (look at its code and you will
1575	understand why). Callback invocation also has a high overhead compared to	2671	understand why). Callback invocation also has a high overhead compared to
1576	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2672	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1577	uses select or poll in basically all documented configurations.	2673	uses select or poll in basically all documented configurations.
…		…
1640	=item * C-based event loops perform very well with small number of	2736	=item * C-based event loops perform very well with small number of
1641	watchers, as the management overhead dominates.	2737	watchers, as the management overhead dominates.
1642		2738
1643	=back	2739	=back
1644		2740
		2741	=head2 THE IO::Lambda BENCHMARK
		2742
		2743	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2744	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2745	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2746	shouldn't come as a surprise to anybody). As such, the benchmark is
		2747	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2748	very optimal. But how would AnyEvent compare when used without the extra
		2749	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2750
		2751	The benchmark itself creates an echo-server, and then, for 500 times,
		2752	connects to the echo server, sends a line, waits for the reply, and then
		2753	creates the next connection. This is a rather bad benchmark, as it doesn't
		2754	test the efficiency of the framework or much non-blocking I/O, but it is a
		2755	benchmark nevertheless.
		2756
		2757	name runtime
		2758	Lambda/select 0.330 sec
		2759	+ optimized 0.122 sec
		2760	Lambda/AnyEvent 0.327 sec
		2761	+ optimized 0.138 sec
		2762	Raw sockets/select 0.077 sec
		2763	POE/select, components 0.662 sec
		2764	POE/select, raw sockets 0.226 sec
		2765	POE/select, optimized 0.404 sec
		2766
		2767	AnyEvent/select/nb 0.085 sec
		2768	AnyEvent/EV/nb 0.068 sec
		2769	+state machine 0.134 sec
		2770
		2771	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2772	benchmarks actually make blocking connects and use 100% blocking I/O,
		2773	defeating the purpose of an event-based solution. All of the newly
		2774	written AnyEvent benchmarks use 100% non-blocking connects (using
		2775	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2776	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2777	generally require a lot more bookkeeping and event handling than blocking
		2778	connects (which involve a single syscall only).
		2779
		2780	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2781	offers similar expressive power as POE and IO::Lambda, using conventional
		2782	Perl syntax. This means that both the echo server and the client are 100%
		2783	non-blocking, further placing it at a disadvantage.
		2784
		2785	As you can see, the AnyEvent + EV combination even beats the
		2786	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2787	backend easily beats IO::Lambda and POE.
		2788
		2789	And even the 100% non-blocking version written using the high-level (and
		2790	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2791	higher level ("unoptimised") abstractions by a large margin, even though
		2792	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2793
		2794	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2795	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2796	part of the IO::Lambda distribution and were used without any changes.
		2797
		2798
		2799	=head1 SIGNALS
		2800
		2801	AnyEvent currently installs handlers for these signals:
		2802
		2803	=over 4
		2804
		2805	=item SIGCHLD
		2806
		2807	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2808	emulation for event loops that do not support them natively. Also, some
		2809	event loops install a similar handler.
		2810
		2811	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2812	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2813
		2814	=item SIGPIPE
		2815
		2816	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2817	when AnyEvent gets loaded.
		2818
		2819	The rationale for this is that AnyEvent users usually do not really depend
		2820	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2821	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2822	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2823	some random socket.
		2824
		2825	The rationale for installing a no-op handler as opposed to ignoring it is
		2826	that this way, the handler will be restored to defaults on exec.
		2827
		2828	Feel free to install your own handler, or reset it to defaults.
		2829
		2830	=back
		2831
		2832	=cut
		2833
		2834	undef $SIG{CHLD}
		2835	if $SIG{CHLD} eq 'IGNORE';
		2836
		2837	$SIG{PIPE} = sub { }
		2838	unless defined $SIG{PIPE};
		2839
		2840	=head1 RECOMMENDED/OPTIONAL MODULES
		2841
		2842	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2843	its built-in modules) are required to use it.
		2844
		2845	That does not mean that AnyEvent won't take advantage of some additional
		2846	modules if they are installed.
		2847
		2848	This section explains which additional modules will be used, and how they
		2849	affect AnyEvent's operation.
		2850
		2851	=over 4
		2852
		2853	=item L<Async::Interrupt>
		2854
		2855	This slightly arcane module is used to implement fast signal handling: To
		2856	my knowledge, there is no way to do completely race-free and quick
		2857	signal handling in pure perl. To ensure that signals still get
		2858	delivered, AnyEvent will start an interval timer to wake up perl (and
		2859	catch the signals) with some delay (default is 10 seconds, look for
		2860	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2861
		2862	If this module is available, then it will be used to implement signal
		2863	catching, which means that signals will not be delayed, and the event loop
		2864	will not be interrupted regularly, which is more efficient (and good for
		2865	battery life on laptops).
		2866
		2867	This affects not just the pure-perl event loop, but also other event loops
		2868	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2869
		2870	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2871	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2872	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2873	does nothing for those backends.
		2874
		2875	=item L<EV>
		2876
		2877	This module isn't really "optional", as it is simply one of the backend
		2878	event loops that AnyEvent can use. However, it is simply the best event
		2879	loop available in terms of features, speed and stability: It supports
		2880	the AnyEvent API optimally, implements all the watcher types in XS, does
		2881	automatic timer adjustments even when no monotonic clock is available,
		2882	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2883	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2884	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2885
		2886	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2887	then this module will do nothing for you.
		2888
		2889	=item L<Guard>
		2890
		2891	The guard module, when used, will be used to implement
		2892	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2893	lot less memory), but otherwise doesn't affect guard operation much. It is
		2894	purely used for performance.
		2895
		2896	=item L<JSON> and L<JSON::XS>
		2897
		2898	One of these modules is required when you want to read or write JSON data
		2899	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2900	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2901
		2902	=item L<Net::SSLeay>
		2903
		2904	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2905	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2906	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2907
		2908	=item L<Time::HiRes>
		2909
		2910	This module is part of perl since release 5.008. It will be used when the
		2911	chosen event library does not come with a timing source of its own. The
		2912	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2913	try to use a monotonic clock for timing stability.
		2914
		2915	=back
		2916
1645		2917
1646	=head1 FORK	2918	=head1 FORK
1647		2919
1648	Most event libraries are not fork-safe. The ones who are usually are	2920	Most event libraries are not fork-safe. The ones who are usually are
1649	because they rely on inefficient but fork-safe C<select> or C<poll>	2921	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1650	calls. Only L<EV> is fully fork-aware.	2922	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2923	are usually badly thought-out hacks that are incompatible with fork in
		2924	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2925	continue event-processing in both parent and child (or both, if you know
		2926	what you are doing).
		2927
		2928	This means that, in general, you cannot fork and do event processing in
		2929	the child if the event library was initialised before the fork (which
		2930	usually happens when the first AnyEvent watcher is created, or the library
		2931	is loaded).
1651		2932
1652	If you have to fork, you must either do so I<before> creating your first	2933	If you have to fork, you must either do so I<before> creating your first
1653	watcher OR you must not use AnyEvent at all in the child.	2934	watcher OR you must not use AnyEvent at all in the child OR you must do
		2935	something completely out of the scope of AnyEvent.
		2936
		2937	The problem of doing event processing in the parent I<and> the child
		2938	is much more complicated: even for backends that I<are> fork-aware or
		2939	fork-safe, their behaviour is not usually what you want: fork clones all
		2940	watchers, that means all timers, I/O watchers etc. are active in both
		2941	parent and child, which is almost never what you want. USing C<exec>
		2942	to start worker children from some kind of manage rprocess is usually
		2943	preferred, because it is much easier and cleaner, at the expense of having
		2944	to have another binary.
1654		2945
1655		2946
1656	=head1 SECURITY CONSIDERATIONS	2947	=head1 SECURITY CONSIDERATIONS
1657		2948
1658	AnyEvent can be forced to load any event model via	2949	AnyEvent can be forced to load any event model via
…		…
1669		2960
1670	use AnyEvent;	2961	use AnyEvent;
1671		2962
1672	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2963	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1673	be used to probe what backend is used and gain other information (which is	2964	be used to probe what backend is used and gain other information (which is
1674	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2965	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2966	$ENV{PERL_ANYEVENT_STRICT}.
		2967
		2968	Note that AnyEvent will remove I<all> environment variables starting with
		2969	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2970	enabled.
		2971
		2972
		2973	=head1 BUGS
		2974
		2975	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2976	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2977	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2978	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2979	pronounced).
1675		2980
1676		2981
1677	=head1 SEE ALSO	2982	=head1 SEE ALSO
1678		2983
1679	Utility functions: L<AnyEvent::Util>.	2984	Tutorial/Introduction: L<AnyEvent::Intro>.
1680		2985
1681	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2986	FAQ: L<AnyEvent::FAQ>.
1682	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2987
		2988	Utility functions: L<AnyEvent::Util> (misc. grab-bag), L<AnyEvent::Log>
		2989	(simply logging).
		2990
		2991	Development/Debugging: L<AnyEvent::Strict> (stricter checking),
		2992	L<AnyEvent::Debug> (interactive shell, watcher tracing).
		2993
		2994	Supported event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>,
		2995	L<Glib::EV>, L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>,
		2996	L<Qt>, L<POE>, L<FLTK>.
1683		2997
1684	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2998	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1685	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2999	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1686	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	3000	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
		3001	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>,
1687	L<AnyEvent::Impl::POE>.	3002	L<AnyEvent::Impl::FLTK>.
1688		3003
1689	Non-blocking file handles, sockets, TCP clients and	3004	Non-blocking handles, pipes, stream sockets, TCP clients and
1690	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	3005	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1691		3006
1692	Asynchronous DNS: L<AnyEvent::DNS>.	3007	Asynchronous DNS: L<AnyEvent::DNS>.
1693		3008
1694	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	3009	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1695		3010
1696	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	3011	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		3012	L<AnyEvent::HTTP>.
1697		3013
1698		3014
1699	=head1 AUTHOR	3015	=head1 AUTHOR
1700		3016
1701	Marc Lehmann <schmorp@schmorp.de>	3017	Marc Lehmann <schmorp@schmorp.de>

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