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Revision 1.144 by root, Thu May 29 00:14:35 2008 UTC vs.
Revision 1.385 by root, Mon Sep 5 08:51:14 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 });
		42
		43	=head1 INTRODUCTION/TUTORIAL
		44
		45	This manpage is mainly a reference manual. If you are interested
		46	in a tutorial or some gentle introduction, have a look at the
		47	L<AnyEvent::Intro> manpage.
		48
		49	=head1 SUPPORT
		50
		51	An FAQ document is available as L<AnyEvent::FAQ>.
		52
		53	There also is a mailinglist for discussing all things AnyEvent, and an IRC
		54	channel, too.
		55
		56	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		57	Repository>, at L<http://anyevent.schmorp.de>, for more info.
22		58
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		60
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	61	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
27		63
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	64	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	65	policy> and AnyEvent is I<small and efficient>.
30		66
31	First and foremost, I<AnyEvent is not an event model> itself, it only	67	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	68	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	69	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	70	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	71	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	72	cannot change this, but it can hide the differences between those event
		73	loops.
37		74
38	The goal of AnyEvent is to offer module authors the ability to do event	75	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	76	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	77	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	78	module users into the same thing by forcing them to use the same event
42	model you use.	79	model you use.
43		80
44	For modules like POE or IO::Async (which is a total misnomer as it is	81	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	82	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	83	like joining a cult: After you join, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	84	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	85	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	86	module are I<also> forced to use the same event loop you use.
50		87
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	89	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	90	with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
54	your module uses one of those, every user of your module has to use it,	91	uses one of those, every user of your module has to use it, too. But if
55	too. But if your module uses AnyEvent, it works transparently with all	92	your module uses AnyEvent, it works transparently with all event models it
56	event models it supports (including stuff like POE and IO::Async, as long	93	supports (including stuff like IO::Async, as long as those use one of the
57	as those use one of the supported event loops. It is trivial to add new	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
58	event loops to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
59		96
60	In addition to being free of having to use I<the one and only true event	97	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	98	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an 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
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	100	follow. AnyEvent, on the other hand, is lean and to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	101	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	102	technically possible.
66		103
67	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
68	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
74	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
75	model, you should I<not> use this module.	112	model, you should I<not> use this module.
76		113
77	=head1 DESCRIPTION	114	=head1 DESCRIPTION
78		115
79	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
80	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
81	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
82	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
83		120
84	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>
85	module.	122	module.
86		123
87	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
88	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
89	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
90	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
91	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
92	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
93	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
94	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
95	found, AnyEvent will fall back to a pure-perl event loop, which is not
96	very efficient, but should work everywhere.
97		132
98	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
99	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
100	that model the default. For example:	135	that model the default. For example:
101		136
…		…
103	use AnyEvent;	138	use AnyEvent;
104		139
105	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
106		141
107	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
108	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,
109	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
110		146
111	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
112	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
113	explicitly and enjoy the high availability of that event loop :)	149	availability of that event loop :)
114		150
115	=head1 WATCHERS	151	=head1 WATCHERS
116		152
117	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
118	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
…		…
121	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
122	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
123	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
124	is in control).	160	is in control).
125		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
126	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
127	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
128	to it).	170	to it).
129		171
130	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.
131		173
132	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
133	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.
134		176
135	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
136		178
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
139	undef $w;	181	undef $w;
140	});	182	});
141		183
142	Note that C<my $w; $w => combination. This is necessary because in Perl,	184	Note that C<my $w; $w => combination. This is necessary because in Perl,
143	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
144	declared.	186	declared.
145		187
146	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
147		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
148	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
149	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
150		198
151	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
152	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
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
154	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.
155	becomes ready.
156		210
157	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
160		214
161	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.
162	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
163	underlying file descriptor.	217	underlying file descriptor.
164		218
165	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
166	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
167	handles.	221	handles.
168		222
169	Example:
170
171	# 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
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	226	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	227	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	228	warn "read: $input\n";
175	undef $w;	229	undef $w;
176	});	230	});
177		231
178	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
179		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
180	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 >>
181	method with the following mandatory arguments:	243	method with the following mandatory arguments:
182		244
183	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
184	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
…		…
186		248
187	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
190		252
191	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
192	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
193	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.
194		258
195	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.
196		262
197	# fire an event after 7.7 seconds	263	Example: fire an event after 7.7 seconds.
		264
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	266	warn "timeout\n";
200	});	267	});
201		268
202	# to cancel the timer:	269	# to cancel the timer:
203	undef $w;	270	undef $w;
204		271
205	Example 2:
206
207	# 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.
208	my $w;
209		273
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	274	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		275	warn "timeout\n";
213	};	276	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		277
218	=head3 TIMING ISSUES	278	=head3 TIMING ISSUES
219		279
220	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
221	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
…		…
223		283
224	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
225	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
226	"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
227	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
228	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.
229		289
230	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
231	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
232	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)
233	timers.	293	timers.
234		294
235	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
236	AnyEvent API.	296	AnyEvent API.
…		…
258	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
259	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
260		320
261	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
262	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
263	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
264		324
265	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
266	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
267		327
268	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>
269	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
270		330
271	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
272	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
273	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
274	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
275	after three seconds.	335	after three seconds.
276		336
…		…
294	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
295	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
296	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
297	account.	357	account.
298		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
299	=back	381	=back
300		382
301	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
302		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		386
303	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
304	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
305	be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
306		390
307	Although the callback might get passed parameters, their value and	391	Although the callback might get passed parameters, their value and
308	presence is undefined and you cannot rely on them. Portable AnyEvent	392	presence is undefined and you cannot rely on them. Portable AnyEvent
309	callbacks cannot use arguments passed to signal watcher callbacks.	393	callbacks cannot use arguments passed to signal watcher callbacks.
310		394
…		…
312	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
313	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,
314	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
315		399
316	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
317	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
318		403
319	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
320	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
321		407
322	Example: exit on SIGINT	408	Example: exit on SIGINT
323		409
324	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
325		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		437	variable can be changed only before the first signal watcher is created,
		438	and should be left alone otherwise. This variable determines how often
		439	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		440	will cause fewer spurious wake-ups, which is better for power and CPU
		441	saving.
		442
		443	All these problems can be avoided by installing the optional
		444	L<Async::Interrupt> module, which works with most event loops. It will not
		445	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		446	(and not with L<POE> currently, as POE does its own workaround with
		447	one-second latency). For those, you just have to suffer the delays.
		448
326	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
327		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
328	You can also watch on a child process exit and catch its exit status.	453	You can also watch for a child process exit and catch its exit status.
329		454
330	The child process is specified by the C<pid> argument (if set to C<0>, it	455	The child process is specified by the C<pid> argument (on some backends,
331	watches for any child process exit). The watcher will trigger as often	456	using C<0> watches for any child process exit, on others this will
332	as status change for the child are received. This works by installing a	457	croak). The watcher will be triggered only when the child process has
333	signal handler for C<SIGCHLD>. The callback will be called with the pid	458	finished and an exit status is available, not on any trace events
334	and exit status (as returned by waitpid), so unlike other watcher types,	459	(stopped/continued).
335	you I<can> rely on child watcher callback arguments.	460
		461	The callback will be called with the pid and exit status (as returned by
		462	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		463	callback arguments.
		464
		465	This watcher type works by installing a signal handler for C<SIGCHLD>,
		466	and since it cannot be shared, nothing else should use SIGCHLD or reap
		467	random child processes (waiting for specific child processes, e.g. inside
		468	C<system>, is just fine).
336		469
337	There is a slight catch to child watchers, however: you usually start them	470	There is a slight catch to child watchers, however: you usually start them
338	I<after> the child process was created, and this means the process could	471	I<after> the child process was created, and this means the process could
339	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
340		473
341	Not all event models handle this correctly (POE doesn't), but even for	474	Not all event models handle this correctly (neither POE nor IO::Async do,
		475	see their AnyEvent::Impl manpages for details), but even for event models
342	event models that I<do> handle this correctly, they usually need to be	476	that I<do> handle this correctly, they usually need to be loaded before
343	loaded before the process exits (i.e. before you fork in the first place).	477	the process exits (i.e. before you fork in the first place). AnyEvent's
		478	pure perl event loop handles all cases correctly regardless of when you
		479	start the watcher.
344		480
345	This means you cannot create a child watcher as the very first thing in an	481	This means you cannot create a child watcher as the very first
346	AnyEvent program, you I<have> to create at least one watcher before you	482	thing in an AnyEvent program, you I<have> to create at least one
347	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	483	watcher before you C<fork> the child (alternatively, you can call
		484	C<AnyEvent::detect>).
		485
		486	As most event loops do not support waiting for child events, they will be
		487	emulated by AnyEvent in most cases, in which case the latency and race
		488	problems mentioned in the description of signal watchers apply.
348		489
349	Example: fork a process and wait for it	490	Example: fork a process and wait for it
350		491
351	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
352		493
353	my $pid = fork or exit 5;	494	my $pid = fork or exit 5;
354		495
355	my $w = AnyEvent->child (	496	my $w = AnyEvent->child (
356	pid => $pid,	497	pid => $pid,
357	cb => sub {	498	cb => sub {
358	my ($pid, $status) = @_;	499	my ($pid, $status) = @_;
359	warn "pid $pid exited with status $status";	500	warn "pid $pid exited with status $status";
360	$done->send;	501	$done->send;
361	},	502	},
362	);	503	);
363		504
364	# do something else, then wait for process exit	505	# do something else, then wait for process exit
365	$done->recv;	506	$done->recv;
		507
		508	=head2 IDLE WATCHERS
		509
		510	$w = AnyEvent->idle (cb => <callback>);
		511
		512	This will repeatedly invoke the callback after the process becomes idle,
		513	until either the watcher is destroyed or new events have been detected.
		514
		515	Idle watchers are useful when there is a need to do something, but it
		516	is not so important (or wise) to do it instantly. The callback will be
		517	invoked only when there is "nothing better to do", which is usually
		518	defined as "all outstanding events have been handled and no new events
		519	have been detected". That means that idle watchers ideally get invoked
		520	when the event loop has just polled for new events but none have been
		521	detected. Instead of blocking to wait for more events, the idle watchers
		522	will be invoked.
		523
		524	Unfortunately, most event loops do not really support idle watchers (only
		525	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		526	will simply call the callback "from time to time".
		527
		528	Example: read lines from STDIN, but only process them when the
		529	program is otherwise idle:
		530
		531	my @lines; # read data
		532	my $idle_w;
		533	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		534	push @lines, scalar <STDIN>;
		535
		536	# start an idle watcher, if not already done
		537	$idle_w ||= AnyEvent->idle (cb => sub {
		538	# handle only one line, when there are lines left
		539	if (my $line = shift @lines) {
		540	print "handled when idle: $line";
		541	} else {
		542	# otherwise disable the idle watcher again
		543	undef $idle_w;
		544	}
		545	});
		546	});
366		547
367	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
368		554
369	If you are familiar with some event loops you will know that all of them	555	If you are familiar with some event loops you will know that all of them
370	require you to run some blocking "loop", "run" or similar function that	556	require you to run some blocking "loop", "run" or similar function that
371	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
372		558
373	AnyEvent is different, it expects somebody else to run the event loop and	559	AnyEvent is slightly different: it expects somebody else to run the event
374	will only block when necessary (usually when told by the user).	560	loop and will only block when necessary (usually when told by the user).
375		561
376	The instrument to do that is called a "condition variable", so called	562	The tool to do that is called a "condition variable", so called because
377	because they represent a condition that must become true.	563	they represent a condition that must become true.
		564
		565	Now is probably a good time to look at the examples further below.
378		566
379	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
380	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
381	C<cb>, which specifies a callback to be called when the condition variable	569	C<cb>, which specifies a callback to be called when the condition variable
382	becomes true.	570	becomes true, with the condition variable as the first argument (but not
		571	the results).
383		572
384	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
385	by calling the C<send> method (or calling the condition variable as if it	574	by calling the C<send> method (or calling the condition variable as if it
386	were a callback, read about the caveats in the description for the C<<	575	were a callback, read about the caveats in the description for the C<<
387	->send >> method).	576	->send >> method).
388		577
389	Condition variables are similar to callbacks, except that you can	578	Since condition variables are the most complex part of the AnyEvent API, here are
390	optionally wait for them. They can also be called merge points - points	579	some different mental models of what they are - pick the ones you can connect to:
391	in time where multiple outstanding events have been processed. And yet	580
392	another way to call them is transactions - each condition variable can be	581	=over 4
393	used to represent a transaction, which finishes at some point and delivers	582
394	a result.	583	=item * Condition variables are like callbacks - you can call them (and pass them instead
		584	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		585
		586	=item * Condition variables are signals - one side can emit or send them,
		587	the other side can wait for them, or install a handler that is called when
		588	the signal fires.
		589
		590	=item * Condition variables are like "Merge Points" - points in your program
		591	where you merge multiple independent results/control flows into one.
		592
		593	=item * Condition variables represent a transaction - functions that start
		594	some kind of transaction can return them, leaving the caller the choice
		595	between waiting in a blocking fashion, or setting a callback.
		596
		597	=item * Condition variables represent future values, or promises to deliver
		598	some result, long before the result is available.
		599
		600	=back
395		601
396	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
397	for example, if you write a module that does asynchronous http requests,	603	for example, if you write a module that does asynchronous http requests,
398	then a condition variable would be the ideal candidate to signal the	604	then a condition variable would be the ideal candidate to signal the
399	availability of results. The user can either act when the callback is	605	availability of results. The user can either act when the callback is
…		…
412		618
413	Condition variables are represented by hash refs in perl, and the keys	619	Condition variables are represented by hash refs in perl, and the keys
414	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	620	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
415	easy (it is often useful to build your own transaction class on top of	621	easy (it is often useful to build your own transaction class on top of
416	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	622	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
417	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
418		624
419	There are two "sides" to a condition variable - the "producer side" which	625	There are two "sides" to a condition variable - the "producer side" which
420	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
421	for the send to occur.	627	for the send to occur.
422		628
423	Example: wait for a timer.	629	Example: wait for a timer.
424		630
425	# wait till the result is ready	631	# condition: "wait till the timer is fired"
426	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
427		633
428	# do something such as adding a timer	634	# create the timer - we could wait for, say
429	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
430	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
431	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
432	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
433	after => 1,	639	after => 1,
434	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
435	);	641	);
436		642
437	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
438	# calls send	644	# calls ->send
439	$result_ready->recv;	645	$timer_fired->recv;
440		646
441	Example: wait for a timer, but take advantage of the fact that	647	Example: wait for a timer, but take advantage of the fact that condition
442	condition variables are also code references.	648	variables are also callable directly.
443		649
444	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
445	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
446	$done->recv;	652	$done->recv;
		653
		654	Example: Imagine an API that returns a condvar and doesn't support
		655	callbacks. This is how you make a synchronous call, for example from
		656	the main program:
		657
		658	use AnyEvent::CouchDB;
		659
		660	...
		661
		662	my @info = $couchdb->info->recv;
		663
		664	And this is how you would just set a callback to be called whenever the
		665	results are available:
		666
		667	$couchdb->info->cb (sub {
		668	my @info = $_[0]->recv;
		669	});
447		670
448	=head3 METHODS FOR PRODUCERS	671	=head3 METHODS FOR PRODUCERS
449		672
450	These methods should only be used by the producing side, i.e. the	673	These methods should only be used by the producing side, i.e. the
451	code/module that eventually sends the signal. Note that it is also	674	code/module that eventually sends the signal. Note that it is also
…		…
464	immediately from within send.	687	immediately from within send.
465		688
466	Any arguments passed to the C<send> call will be returned by all	689	Any arguments passed to the C<send> call will be returned by all
467	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
468		691
469	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
470	(as a code reference). Calling them directly is the same as calling	693	they were a code reference). Calling them directly is the same as calling
471	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
472	overloading, so as tempting as it may be, passing a condition variable
473	instead of a callback does not work. Both the pure perl and EV loops
474	support overloading, however, as well as all functions that use perl to
475	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
476	example).
477		695
478	=item $cv->croak ($error)	696	=item $cv->croak ($error)
479		697
480	Similar to send, but causes all call's to C<< ->recv >> to invoke	698	Similar to send, but causes all calls to C<< ->recv >> to invoke
481	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
482		700
483	This can be used to signal any errors to the condition variable	701	This can be used to signal any errors to the condition variable
484	user/consumer.	702	user/consumer. Doing it this way instead of calling C<croak> directly
		703	delays the error detection, but has the overwhelming advantage that it
		704	diagnoses the error at the place where the result is expected, and not
		705	deep in some event callback with no connection to the actual code causing
		706	the problem.
485		707
486	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
487		709
488	=item $cv->end	710	=item $cv->end
489
490	These two methods are EXPERIMENTAL and MIGHT CHANGE.
491		711
492	These two methods can be used to combine many transactions/events into	712	These two methods can be used to combine many transactions/events into
493	one. For example, a function that pings many hosts in parallel might want	713	one. For example, a function that pings many hosts in parallel might want
494	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
495		715
496	Every call to C<< ->begin >> will increment a counter, and every call to	716	Every call to C<< ->begin >> will increment a counter, and every call to
497	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	717	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
498	>>, the (last) callback passed to C<begin> will be executed. That callback	718	>>, the (last) callback passed to C<begin> will be executed, passing the
499	is I<supposed> to call C<< ->send >>, but that is not required. If no	719	condvar as first argument. That callback is I<supposed> to call C<< ->send
500	callback was set, C<send> will be called without any arguments.	720	>>, but that is not required. If no group callback was set, C<send> will
		721	be called without any arguments.
501		722
502	Let's clarify this with the ping example:	723	You can think of C<< $cv->send >> giving you an OR condition (one call
		724	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		725	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		726
		727	Let's start with a simple example: you have two I/O watchers (for example,
		728	STDOUT and STDERR for a program), and you want to wait for both streams to
		729	close before activating a condvar:
503		730
504	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
505		732
		733	$cv->begin; # first watcher
		734	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		735	defined sysread $fh1, my $buf, 4096
		736	or $cv->end;
		737	});
		738
		739	$cv->begin; # second watcher
		740	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		741	defined sysread $fh2, my $buf, 4096
		742	or $cv->end;
		743	});
		744
		745	$cv->recv;
		746
		747	This works because for every event source (EOF on file handle), there is
		748	one call to C<begin>, so the condvar waits for all calls to C<end> before
		749	sending.
		750
		751	The ping example mentioned above is slightly more complicated, as the
		752	there are results to be passwd back, and the number of tasks that are
		753	begun can potentially be zero:
		754
		755	my $cv = AnyEvent->condvar;
		756
506	my %result;	757	my %result;
507	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
508		759
509	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
510	$cv->begin;	761	$cv->begin;
511	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
512	$result{$host} = ...;	763	$result{$host} = ...;
…		…
527	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
528	to be called once the counter reaches C<0>, and second, it ensures that	779	to be called once the counter reaches C<0>, and second, it ensures that
529	C<send> is called even when C<no> hosts are being pinged (the loop	780	C<send> is called even when C<no> hosts are being pinged (the loop
530	doesn't execute once).	781	doesn't execute once).
531		782
532	This is the general pattern when you "fan out" into multiple subrequests:	783	This is the general pattern when you "fan out" into multiple (but
533	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	784	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
534	is called at least once, and then, for each subrequest you start, call	785	the callback and ensure C<end> is called at least once, and then, for each
535	C<begin> and for each subrequest you finish, call C<end>.	786	subrequest you start, call C<begin> and for each subrequest you finish,
		787	call C<end>.
536		788
537	=back	789	=back
538		790
539	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
540		792
…		…
544	=over 4	796	=over 4
545		797
546	=item $cv->recv	798	=item $cv->recv
547		799
548	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
549	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
550	normally.	802	normally.
551		803
552	You can only wait once on a condition - additional calls are valid but	804	You can only wait once on a condition - additional calls are valid but
553	will return immediately.	805	will return immediately.
554		806
…		…
556	function will call C<croak>.	808	function will call C<croak>.
557		809
558	In list context, all parameters passed to C<send> will be returned,	810	In list context, all parameters passed to C<send> will be returned,
559	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
560		812
		813	Note that doing a blocking wait in a callback is not supported by any
		814	event loop, that is, recursive invocation of a blocking C<< ->recv
		815	>> is not allowed, and the C<recv> call will C<croak> if such a
		816	condition is detected. This condition can be slightly loosened by using
		817	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		818	any thread that doesn't run the event loop itself.
		819
561	Not all event models support a blocking wait - some die in that case	820	Not all event models support a blocking wait - some die in that case
562	(programs might want to do that to stay interactive), so I<if you are	821	(programs might want to do that to stay interactive), so I<if you are
563	using this from a module, never require a blocking wait>, but let the	822	using this from a module, never require a blocking wait>. Instead, let the
564	caller decide whether the call will block or not (for example, by coupling	823	caller decide whether the call will block or not (for example, by coupling
565	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
566	callbacks so the caller knows that getting the result will not block,	825	callbacks so the caller knows that getting the result will not block,
567	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
568		827
569	Another reason I<never> to C<< ->recv >> in a module is that you cannot
570	sensibly have two C<< ->recv >>'s in parallel, as that would require
571	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
572	can supply.
573
574	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
575	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
576	versions and also integrates coroutines into AnyEvent, making blocking
577	C<< ->recv >> calls perfectly safe as long as they are done from another
578	coroutine (one that doesn't run the event loop).
579
580	You can ensure that C<< -recv >> never blocks by setting a callback and	828	You can ensure that C<< ->recv >> never blocks by setting a callback and
581	only calling C<< ->recv >> from within that callback (or at a later	829	only calling C<< ->recv >> from within that callback (or at a later
582	time). This will work even when the event loop does not support blocking	830	time). This will work even when the event loop does not support blocking
583	waits otherwise.	831	waits otherwise.
584		832
585	=item $bool = $cv->ready	833	=item $bool = $cv->ready
586		834
587	Returns true when the condition is "true", i.e. whether C<send> or	835	Returns true when the condition is "true", i.e. whether C<send> or
588	C<croak> have been called.	836	C<croak> have been called.
589		837
590	=item $cb = $cv->cb ([new callback])	838	=item $cb = $cv->cb ($cb->($cv))
591		839
592	This is a mutator function that returns the callback set and optionally	840	This is a mutator function that returns the callback set and optionally
593	replaces it before doing so.	841	replaces it before doing so.
594		842
595	The callback will be called when the condition becomes "true", i.e. when	843	The callback will be called when the condition becomes "true", i.e. when
596	C<send> or C<croak> are called. Calling C<recv> inside the callback	844	C<send> or C<croak> are called, with the only argument being the
		845	condition variable itself. If the condition is already true, the
		846	callback is called immediately when it is set. Calling C<recv> inside
597	or at any later time is guaranteed not to block.	847	the callback or at any later time is guaranteed not to block.
598		848
599	=back	849	=back
600		850
		851	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		852
		853	The available backend classes are (every class has its own manpage):
		854
		855	=over 4
		856
		857	=item Backends that are autoprobed when no other event loop can be found.
		858
		859	EV is the preferred backend when no other event loop seems to be in
		860	use. If EV is not installed, then AnyEvent will fall back to its own
		861	pure-perl implementation, which is available everywhere as it comes with
		862	AnyEvent itself.
		863
		864	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		865	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
		866
		867	=item Backends that are transparently being picked up when they are used.
		868
		869	These will be used if they are already loaded when the first watcher
		870	is created, in which case it is assumed that the application is using
		871	them. This means that AnyEvent will automatically pick the right backend
		872	when the main program loads an event module before anything starts to
		873	create watchers. Nothing special needs to be done by the main program.
		874
		875	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		876	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		877	AnyEvent::Impl::Tk based on Tk, very broken.
		878	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		879	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		880	AnyEvent::Impl::Irssi used when running within irssi.
		881	AnyEvent::Impl::IOAsync based on IO::Async.
		882	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		883	AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding).
		884
		885	=item Backends with special needs.
		886
		887	Qt requires the Qt::Application to be instantiated first, but will
		888	otherwise be picked up automatically. As long as the main program
		889	instantiates the application before any AnyEvent watchers are created,
		890	everything should just work.
		891
		892	AnyEvent::Impl::Qt based on Qt.
		893
		894	=item Event loops that are indirectly supported via other backends.
		895
		896	Some event loops can be supported via other modules:
		897
		898	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		899
		900	B<WxWidgets> has no support for watching file handles. However, you can
		901	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		902	polls 20 times per second, which was considered to be too horrible to even
		903	consider for AnyEvent.
		904
		905	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		906	backend, so it can be supported through POE.
		907
		908	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		909	load L<POE> when detecting them, in the hope that POE will pick them up,
		910	in which case everything will be automatic.
		911
		912	=back
		913
601	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
602		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
603	=over 4	919	=over 4
604		920
605	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
606		922
607	Contains C<undef> until the first watcher is being created. Then it	923	Contains C<undef> until the first watcher is being created, before the
		924	backend has been autodetected.
		925
608	contains the event model that is being used, which is the name of the	926	Afterwards it contains the event model that is being used, which is the
609	Perl class implementing the model. This class is usually one of the	927	name of the Perl class implementing the model. This class is usually one
610	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
611	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
612		930	will be C<urxvt::anyevent>).
613	The known classes so far are:
614
615	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
616	AnyEvent::Impl::Event based on Event, second best choice.
617	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
618	AnyEvent::Impl::Glib based on Glib, third-best choice.
619	AnyEvent::Impl::Tk based on Tk, very bad choice.
620	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
621	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
622	AnyEvent::Impl::POE based on POE, not generic enough for full support.
623
624	There is no support for WxWidgets, as WxWidgets has no support for
625	watching file handles. However, you can use WxWidgets through the
626	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
627	second, which was considered to be too horrible to even consider for
628	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
629	it's adaptor.
630
631	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
632	autodetecting them.
633		931
634	=item AnyEvent::detect	932	=item AnyEvent::detect
635		933
636	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
637	if necessary. You should only call this function right before you would	935	if necessary. You should only call this function right before you would
638	have created an AnyEvent watcher anyway, that is, as late as possible at	936	have created an AnyEvent watcher anyway, that is, as late as possible at
639	runtime.	937	runtime, and not e.g. during initialisation of your module.
		938
		939	The effect of calling this function is as if a watcher had been created
		940	(specifically, actions that happen "when the first watcher is created"
		941	happen when calling detetc as well).
		942
		943	If you need to do some initialisation before AnyEvent watchers are
		944	created, use C<post_detect>.
640		945
641	=item $guard = AnyEvent::post_detect { BLOCK }	946	=item $guard = AnyEvent::post_detect { BLOCK }
642		947
643	Arranges for the code block to be executed as soon as the event model is	948	Arranges for the code block to be executed as soon as the event model is
644	autodetected (or immediately if this has already happened).	949	autodetected (or immediately if that has already happened).
		950
		951	The block will be executed I<after> the actual backend has been detected
		952	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		953	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		954	other initialisations - see the sources of L<AnyEvent::Strict> or
		955	L<AnyEvent::AIO> to see how this is used.
		956
		957	The most common usage is to create some global watchers, without forcing
		958	event module detection too early, for example, L<AnyEvent::AIO> creates
		959	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		960	avoid autodetecting the event module at load time.
645		961
646	If called in scalar or list context, then it creates and returns an object	962	If called in scalar or list context, then it creates and returns an object
647	that automatically removes the callback again when it is destroyed. See	963	that automatically removes the callback again when it is destroyed (or
		964	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
648	L<Coro::BDB> for a case where this is useful.	965	a case where this is useful.
		966
		967	Example: Create a watcher for the IO::AIO module and store it in
		968	C<$WATCHER>, but do so only do so after the event loop is initialised.
		969
		970	our WATCHER;
		971
		972	my $guard = AnyEvent::post_detect {
		973	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		974	};
		975
		976	# the ||= is important in case post_detect immediately runs the block,
		977	# as to not clobber the newly-created watcher. assigning both watcher and
		978	# post_detect guard to the same variable has the advantage of users being
		979	# able to just C<undef $WATCHER> if the watcher causes them grief.
		980
		981	$WATCHER ||= $guard;
649		982
650	=item @AnyEvent::post_detect	983	=item @AnyEvent::post_detect
651		984
652	If there are any code references in this array (you can C<push> to it	985	If there are any code references in this array (you can C<push> to it
653	before or after loading AnyEvent), then they will called directly after	986	before or after loading AnyEvent), then they will be called directly
654	the event loop has been chosen.	987	after the event loop has been chosen.
655		988
656	You should check C<$AnyEvent::MODEL> before adding to this array, though:	989	You should check C<$AnyEvent::MODEL> before adding to this array, though:
657	if it contains a true value then the event loop has already been detected,	990	if it is defined then the event loop has already been detected, and the
658	and the array will be ignored.	991	array will be ignored.
659		992
660	Best use C<AnyEvent::post_detect { BLOCK }> instead.	993	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		994	it, as it takes care of these details.
		995
		996	This variable is mainly useful for modules that can do something useful
		997	when AnyEvent is used and thus want to know when it is initialised, but do
		998	not need to even load it by default. This array provides the means to hook
		999	into AnyEvent passively, without loading it.
		1000
		1001	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1002	together, you could put this into Coro (this is the actual code used by
		1003	Coro to accomplish this):
		1004
		1005	if (defined $AnyEvent::MODEL) {
		1006	# AnyEvent already initialised, so load Coro::AnyEvent
		1007	require Coro::AnyEvent;
		1008	} else {
		1009	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1010	# as soon as it is
		1011	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1012	}
		1013
		1014	=item AnyEvent::postpone { BLOCK }
		1015
		1016	Arranges for the block to be executed as soon as possible, but not before
		1017	the call itself returns. In practise, the block will be executed just
		1018	before the event loop polls for new events, or shortly afterwards.
		1019
		1020	This function never returns anything (to make the C<return postpone { ...
		1021	}> idiom more useful.
		1022
		1023	To understand the usefulness of this function, consider a function that
		1024	asynchronously does something for you and returns some transaction
		1025	object or guard to let you cancel the operation. For example,
		1026	C<AnyEvent::Socket::tcp_connect>:
		1027
		1028	# start a conenction attempt unless one is active
		1029	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1030	delete $self->{connect_guard};
		1031	...
		1032	};
		1033
		1034	Imagine that this function could instantly call the callback, for
		1035	example, because it detects an obvious error such as a negative port
		1036	number. Invoking the callback before the function returns causes problems
		1037	however: the callback will be called and will try to delete the guard
		1038	object. But since the function hasn't returned yet, there is nothing to
		1039	delete. When the function eventually returns it will assign the guard
		1040	object to C<< $self->{connect_guard} >>, where it will likely never be
		1041	deleted, so the program thinks it is still trying to connect.
		1042
		1043	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1044	callback directly on error:
		1045
		1046	$cb->(undef), return # signal error to callback, BAD!
		1047	if $some_error_condition;
		1048
		1049	It should use C<postpone>:
		1050
		1051	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1052	if $some_error_condition;
		1053
		1054	=item AnyEvent::log $level, $msg[, @args]
		1055
		1056	Log the given C<$msg> at the given C<$level>.
		1057
		1058	If L<AnyEvent::Log> is not loaded then this function makes a simple test
		1059	to see whether the message will be logged. If the test succeeds it will
		1060	load AnyEvent::Log and call C<AnyEvent::Log::log> - consequently, look at
		1061	the L<AnyEvent::Log> documentation for details.
		1062
		1063	If the test fails it will simply return. Right now this happens when a
		1064	numerical loglevel is used and it is larger than the level specified via
		1065	C<$ENV{PERL_ANYEVENT_VERBOSE}>.
		1066
		1067	If you want to sprinkle loads of logging calls around your code, consider
		1068	creating a logger callback with the C<AnyEvent::Log::logger> function,
		1069	which can reduce typing, codesize and can reduce the logging overhead
		1070	enourmously.
661		1071
662	=back	1072	=back
663		1073
664	=head1 WHAT TO DO IN A MODULE	1074	=head1 WHAT TO DO IN A MODULE
665		1075
…		…
676	because it will stall the whole program, and the whole point of using	1086	because it will stall the whole program, and the whole point of using
677	events is to stay interactive.	1087	events is to stay interactive.
678		1088
679	It is fine, however, to call C<< ->recv >> when the user of your module	1089	It is fine, however, to call C<< ->recv >> when the user of your module
680	requests it (i.e. if you create a http request object ad have a method	1090	requests it (i.e. if you create a http request object ad have a method
681	called C<results> that returns the results, it should call C<< ->recv >>	1091	called C<results> that returns the results, it may call C<< ->recv >>
682	freely, as the user of your module knows what she is doing. always).	1092	freely, as the user of your module knows what she is doing. Always).
683		1093
684	=head1 WHAT TO DO IN THE MAIN PROGRAM	1094	=head1 WHAT TO DO IN THE MAIN PROGRAM
685		1095
686	There will always be a single main program - the only place that should	1096	There will always be a single main program - the only place that should
687	dictate which event model to use.	1097	dictate which event model to use.
688		1098
689	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1099	If the program is not event-based, it need not do anything special, even
690	do anything special (it does not need to be event-based) and let AnyEvent	1100	when it depends on a module that uses an AnyEvent. If the program itself
691	decide which implementation to chose if some module relies on it.	1101	uses AnyEvent, but does not care which event loop is used, all it needs
		1102	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1103	available loop implementation.
692		1104
693	If the main program relies on a specific event model - for example, in	1105	If the main program relies on a specific event model - for example, in
694	Gtk2 programs you have to rely on the Glib module - you should load the	1106	Gtk2 programs you have to rely on the Glib module - you should load the
695	event module before loading AnyEvent or any module that uses it: generally	1107	event module before loading AnyEvent or any module that uses it: generally
696	speaking, you should load it as early as possible. The reason is that	1108	speaking, you should load it as early as possible. The reason is that
697	modules might create watchers when they are loaded, and AnyEvent will	1109	modules might create watchers when they are loaded, and AnyEvent will
698	decide on the event model to use as soon as it creates watchers, and it	1110	decide on the event model to use as soon as it creates watchers, and it
699	might chose the wrong one unless you load the correct one yourself.	1111	might choose the wrong one unless you load the correct one yourself.
700		1112
701	You can chose to use a pure-perl implementation by loading the	1113	You can chose to use a pure-perl implementation by loading the
702	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1114	C<AnyEvent::Loop> module, which gives you similar behaviour
703	everywhere, but letting AnyEvent chose the model is generally better.	1115	everywhere, but letting AnyEvent chose the model is generally better.
704		1116
705	=head2 MAINLOOP EMULATION	1117	=head2 MAINLOOP EMULATION
706		1118
707	Sometimes (often for short test scripts, or even standalone programs who	1119	Sometimes (often for short test scripts, or even standalone programs who
…		…
720		1132
721		1133
722	=head1 OTHER MODULES	1134	=head1 OTHER MODULES
723		1135
724	The following is a non-exhaustive list of additional modules that use	1136	The following is a non-exhaustive list of additional modules that use
725	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1137	AnyEvent as a client and can therefore be mixed easily with other
726	in the same program. Some of the modules come with AnyEvent, some are	1138	AnyEvent modules and other event loops in the same program. Some of the
727	available via CPAN.	1139	modules come as part of AnyEvent, the others are available via CPAN (see
		1140	L<http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for
		1141	a longer non-exhaustive list), and the list is heavily biased towards
		1142	modules of the AnyEvent author himself :)
728		1143
729	=over 4	1144	=over 4
730		1145
731	=item L<AnyEvent::Util>	1146	=item L<AnyEvent::Util>
732		1147
733	Contains various utility functions that replace often-used but blocking	1148	Contains various utility functions that replace often-used blocking
734	functions such as C<inet_aton> by event-/callback-based versions.	1149	functions such as C<inet_aton> with event/callback-based versions.
735
736	=item L<AnyEvent::Handle>
737
738	Provide read and write buffers and manages watchers for reads and writes.
739		1150
740	=item L<AnyEvent::Socket>	1151	=item L<AnyEvent::Socket>
741		1152
742	Provides various utility functions for (internet protocol) sockets,	1153	Provides various utility functions for (internet protocol) sockets,
743	addresses and name resolution. Also functions to create non-blocking tcp	1154	addresses and name resolution. Also functions to create non-blocking tcp
744	connections or tcp servers, with IPv6 and SRV record support and more.	1155	connections or tcp servers, with IPv6 and SRV record support and more.
745		1156
		1157	=item L<AnyEvent::Handle>
		1158
		1159	Provide read and write buffers, manages watchers for reads and writes,
		1160	supports raw and formatted I/O, I/O queued and fully transparent and
		1161	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
		1162
746	=item L<AnyEvent::DNS>	1163	=item L<AnyEvent::DNS>
747		1164
748	Provides rich asynchronous DNS resolver capabilities.	1165	Provides rich asynchronous DNS resolver capabilities.
749		1166
		1167	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1168
		1169	Implement event-based interfaces to the protocols of the same name (for
		1170	the curious, IGS is the International Go Server and FCP is the Freenet
		1171	Client Protocol).
		1172
		1173	=item L<AnyEvent::AIO>
		1174
		1175	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1176	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1177	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1178	file I/O, and much more.
		1179
		1180	=item L<AnyEvent::Filesys::Notify>
		1181
		1182	AnyEvent is good for non-blocking stuff, but it can't detect file or
		1183	path changes (e.g. "watch this directory for new files", "watch this
		1184	file for changes"). The L<AnyEvent::Filesys::Notify> module promises to
		1185	do just that in a portbale fashion, supporting inotify on GNU/Linux and
		1186	some weird, without doubt broken, stuff on OS X to monitor files. It can
		1187	fall back to blocking scans at regular intervals transparently on other
		1188	platforms, so it's about as portable as it gets.
		1189
		1190	(I haven't used it myself, but I haven't heard anybody complaining about
		1191	it yet).
		1192
		1193	=item L<AnyEvent::DBI>
		1194
		1195	Executes L<DBI> requests asynchronously in a proxy process for you,
		1196	notifying you in an event-based way when the operation is finished.
		1197
750	=item L<AnyEvent::HTTPD>	1198	=item L<AnyEvent::HTTPD>
751		1199
752	Provides a simple web application server framework.	1200	A simple embedded webserver.
753		1201
754	=item L<AnyEvent::FastPing>	1202	=item L<AnyEvent::FastPing>
755		1203
756	The fastest ping in the west.	1204	The fastest ping in the west.
757		1205
758	=item L<Net::IRC3>
759
760	AnyEvent based IRC client module family.
761
762	=item L<Net::XMPP2>
763
764	AnyEvent based XMPP (Jabber protocol) module family.
765
766	=item L<Net::FCP>
767
768	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
769	of AnyEvent.
770
771	=item L<Event::ExecFlow>
772
773	High level API for event-based execution flow control.
774
775	=item L<Coro>	1206	=item L<Coro>
776		1207
777	Has special support for AnyEvent via L<Coro::AnyEvent>.	1208	Has special support for AnyEvent via L<Coro::AnyEvent>, which allows you
		1209	to simply invert the flow control - don't call us, we will call you:
778		1210
779	=item L<AnyEvent::AIO>, L<IO::AIO>	1211	async {
		1212	Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
		1213	print "5 seconds later!\n";
780		1214
781	Truly asynchronous I/O, should be in the toolbox of every event	1215	Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
782	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent	1216	my $line = <STDIN>; # works for ttys
783	together.
784		1217
785	=item L<AnyEvent::BDB>, L<BDB>	1218	AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
786		1219	my ($body, $hdr) = Coro::rouse_wait;
787	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses	1220	};
788	IO::AIO and AnyEvent together.
789
790	=item L<IO::Lambda>
791
792	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
793		1221
794	=back	1222	=back
795		1223
796	=cut	1224	=cut
797		1225
798	package AnyEvent;	1226	package AnyEvent;
799		1227
800	no warnings;	1228	# basically a tuned-down version of common::sense
801	use strict;	1229	sub common_sense {
		1230	# from common:.sense 3.4
		1231	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1232	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1233	$^H |= 0x00000600;
		1234	}
802		1235
		1236	BEGIN { AnyEvent::common_sense }
		1237
803	use Carp;	1238	use Carp ();
804		1239
805	our $VERSION = '4.05';	1240	our $VERSION = '6.02';
806	our $MODEL;	1241	our $MODEL;
807
808	our $AUTOLOAD;
809	our @ISA;	1242	our @ISA;
810
811	our @REGISTRY;	1243	our @REGISTRY;
812		1244	our $VERBOSE;
813	our $WIN32;	1245	our $MAX_SIGNAL_LATENCY = 10;
		1246	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
814		1247
815	BEGIN {	1248	BEGIN {
816	my $win32 = ! ! ($^O =~ /mswin32/i);	1249	require "AnyEvent/constants.pl";
817	eval "sub WIN32(){ $win32 }";
818	}
819		1250
820	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1251	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
821		1252
822	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1253	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1254	if ${^TAINT};
823		1255
824	{	1256	$ENV{"PERL_ANYEVENT_$_"} = $ENV{"AE_$_"}
		1257	for grep s/^AE_// && !exists $ENV{"PERL_ANYEVENT_$_"}, keys %ENV;
		1258
		1259	@ENV{grep /^PERL_ANYEVENT_/, keys %ENV} = ()
		1260	if ${^TAINT};
		1261
		1262	# $ENV{PERL_ANYEVENT_xxx} now valid
		1263
		1264	$VERBOSE = length $ENV{PERL_ANYEVENT_VERBOSE} ? $ENV{PERL_ANYEVENT_VERBOSE}*1 : 4;
		1265
825	my $idx;	1266	my $idx;
826	$PROTOCOL{$_} = ++$idx	1267	$PROTOCOL{$_} = ++$idx
827	for reverse split /\s*,\s*/,	1268	for reverse split /\s*,\s*/,
828	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1269	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
829	}	1270	}
830		1271
		1272	our @post_detect;
		1273
		1274	sub post_detect(&) {
		1275	my ($cb) = @_;
		1276
		1277	push @post_detect, $cb;
		1278
		1279	defined wantarray
		1280	? bless \$cb, "AnyEvent::Util::postdetect"
		1281	: ()
		1282	}
		1283
		1284	sub AnyEvent::Util::postdetect::DESTROY {
		1285	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1286	}
		1287
		1288	our $POSTPONE_W;
		1289	our @POSTPONE;
		1290
		1291	sub _postpone_exec {
		1292	undef $POSTPONE_W;
		1293
		1294	&{ shift @POSTPONE }
		1295	while @POSTPONE;
		1296	}
		1297
		1298	sub postpone(&) {
		1299	push @POSTPONE, shift;
		1300
		1301	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1302
		1303	()
		1304	}
		1305
		1306	sub log($$;@) {
		1307	# only load the big bloated module when we actually are about to log something
		1308	if ($_[0] <= ($VERBOSE || 1)) { # also catches non-numeric levels(!) and fatal
		1309	require AnyEvent::Log; # among other things, sets $VERBOSE to 9
		1310	# AnyEvent::Log overwrites this function
		1311	goto &log;
		1312	}
		1313
		1314	0 # not logged
		1315	}
		1316
		1317	sub logger($;$) {
		1318	package AnyEvent::Log;
		1319
		1320	my ($level, $renabled) = @_;
		1321
		1322	$$renabled = $level <= $VERBOSE;
		1323
		1324	my $pkg = (caller)[0];
		1325
		1326	my $logger = [$pkg, $level, $renabled];
		1327
		1328	our %LOGGER;
		1329	$LOGGER{$logger+0} = $logger;
		1330
		1331	require AnyEvent::Util;
		1332	my $guard = AnyEvent::Util::guard (sub {
		1333	# "clean up"
		1334	delete $LOGGER{$logger+0};
		1335	});
		1336
		1337	sub {
		1338	return 0 unless $$renabled;
		1339
		1340	$guard if 0; # keep guard alive, but don't cause runtime overhead
		1341	require AnyEvent::Log unless $AnyEvent::Log::VERSION;
		1342	package AnyEvent::Log;
		1343	_log ($logger->[0], $level, @_) # logger->[0] has been converted at load time
		1344	}
		1345	}
		1346
		1347	if (length $ENV{PERL_ANYEVENT_LOG}) {
		1348	require AnyEvent::Log; # AnyEvent::Log does the thing for us
		1349	}
		1350
831	my @models = (	1351	our @models = (
832	[EV:: => AnyEvent::Impl::EV::],	1352	[EV:: => AnyEvent::Impl::EV::],
833	[Event:: => AnyEvent::Impl::Event::],
834	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1353	[AnyEvent::Loop:: => AnyEvent::Impl::Perl::],
835	# everything below here will not be autoprobed	1354	# everything below here will not (normally) be autoprobed
836	# as the pureperl backend should work everywhere	1355	# as the pure perl backend should work everywhere
837	# and is usually faster	1356	# and is usually faster
		1357	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package, so msut be near the top
		1358	[Event:: => AnyEvent::Impl::Event::], # slow, stable
		1359	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1360	# everything below here should not be autoloaded
		1361	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
838	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1362	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
839	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
840	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
841	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1363	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
842	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1364	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
843	[Wx:: => AnyEvent::Impl::POE::],	1365	[Wx:: => AnyEvent::Impl::POE::],
844	[Prima:: => AnyEvent::Impl::POE::],	1366	[Prima:: => AnyEvent::Impl::POE::],
		1367	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1368	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1369	[FLTK:: => AnyEvent::Impl::FLTK::],
845	);	1370	);
846		1371
847	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1372	our @isa_hook;
848		1373
849	our @post_detect;	1374	sub _isa_set {
		1375	my @pkg = ("AnyEvent", (map $_->[0], grep defined, @isa_hook), $MODEL);
850		1376
		1377	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1378	for 1 .. $#pkg;
		1379
		1380	grep $_ && $_->[1], @isa_hook
		1381	and AE::_reset ();
		1382	}
		1383
		1384	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1385	sub _isa_hook($$;$) {
		1386	my ($i, $pkg, $reset_ae) = @_;
		1387
		1388	$isa_hook[$i] = $pkg ? [$pkg, $reset_ae] : undef;
		1389
		1390	_isa_set;
		1391	}
		1392
		1393	# all autoloaded methods reserve the complete glob, not just the method slot.
		1394	# due to bugs in perls method cache implementation.
		1395	our @methods = qw(io timer time now now_update signal child idle condvar);
		1396
851	sub post_detect(&) {	1397	sub detect() {
852	my ($cb) = @_;	1398	return $MODEL if $MODEL; # some programs keep references to detect
853		1399
854	if ($MODEL) {	1400	local $!; # for good measure
855	$cb->();	1401	local $SIG{__DIE__}; # we use eval
856		1402
857	1	1403	# free some memory
		1404	*detect = sub () { $MODEL };
		1405	# undef &func doesn't correctly update the method cache. grmbl.
		1406	# so we delete the whole glob. grmbl.
		1407	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1408	# a glob with an active sub. hrm. i hope it works, but perl is
		1409	# usually buggy in this department. sigh.
		1410	delete @{"AnyEvent::"}{@methods};
		1411	undef @methods;
		1412
		1413	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1414	my $model = $1;
		1415	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1416	if (eval "require $model") {
		1417	AnyEvent::log 7 => "loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.";
		1418	$MODEL = $model;
858	} else {	1419	} else {
859	push @post_detect, $cb;	1420	AnyEvent::log 4 => "unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
860		1421	}
861	defined wantarray
862	? bless \$cb, "AnyEvent::Util::PostDetect"
863	: ()
864	}	1422	}
865	}
866		1423
867	sub AnyEvent::Util::PostDetect::DESTROY {	1424	# check for already loaded models
868	@post_detect = grep $_ != ${$_[0]}, @post_detect;
869	}
870
871	sub detect() {
872	unless ($MODEL) {	1425	unless ($MODEL) {
873	no strict 'refs';	1426	for (@REGISTRY, @models) {
874	local $SIG{__DIE__};	1427	my ($package, $model) = @$_;
875		1428	if (${"$package\::VERSION"} > 0) {
876	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
877	my $model = "AnyEvent::Impl::$1";
878	if (eval "require $model") {	1429	if (eval "require $model") {
		1430	AnyEvent::log 7 => "autodetected model '$model', using it.";
879	$MODEL = $model;	1431	$MODEL = $model;
880	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1432	last;
881	} else {	1433	}
882	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;
883	}	1434	}
884	}	1435	}
885		1436
886	# check for already loaded models
887	unless ($MODEL) {	1437	unless ($MODEL) {
		1438	# try to autoload a model
888	for (@REGISTRY, @models) {	1439	for (@REGISTRY, @models) {
889	my ($package, $model) = @$_;	1440	my ($package, $model) = @$_;
		1441	if (
		1442	eval "require $package"
890	if (${"$package\::VERSION"} > 0) {	1443	and ${"$package\::VERSION"} > 0
891	if (eval "require $model") {	1444	and eval "require $model"
		1445	) {
		1446	AnyEvent::log 7 => "autoloaded model '$model', using it.";
892	$MODEL = $model;	1447	$MODEL = $model;
893	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
894	last;	1448	last;
895	}
896	}	1449	}
897	}	1450	}
898		1451
899	unless ($MODEL) {	1452	$MODEL
900	# try to load a model	1453	or AnyEvent::log fatal => "AnyEvent: backend autodetection failed - did you properly install AnyEvent?";
		1454	}
		1455	}
901		1456
902	for (@REGISTRY, @models) {	1457	# free memory only needed for probing
903	my ($package, $model) = @$_;	1458	undef @models;
904	if (eval "require $package"	1459	undef @REGISTRY;
905	and ${"$package\::VERSION"} > 0	1460
906	and eval "require $model") {	1461	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
907	$MODEL = $model;	1462
908	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1463	# now nuke some methods that are overridden by the backend.
		1464	# SUPER usage is not allowed in these.
		1465	for (qw(time signal child idle)) {
		1466	undef &{"AnyEvent::Base::$_"}
		1467	if defined &{"$MODEL\::$_"};
		1468	}
		1469
		1470	_isa_set;
		1471
		1472	# we're officially open!
		1473
		1474	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1475	require AnyEvent::Strict;
		1476	}
		1477
		1478	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1479	require AnyEvent::Debug;
		1480	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1481	}
		1482
		1483	if (length $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1484	require AnyEvent::Socket;
		1485	require AnyEvent::Debug;
		1486
		1487	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1488	$shell =~ s/\$\$/$$/g;
		1489
		1490	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1491	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1492	}
		1493
		1494	# now the anyevent environment is set up as the user told us to, so
		1495	# call the actual user code - post detects
		1496
		1497	(shift @post_detect)->() while @post_detect;
		1498	undef @post_detect;
		1499
		1500	*post_detect = sub(&) {
		1501	shift->();
		1502
		1503	undef
		1504	};
		1505
		1506	$MODEL
		1507	}
		1508
		1509	for my $name (@methods) {
		1510	*$name = sub {
		1511	detect;
		1512	# we use goto because
		1513	# a) it makes the thunk more transparent
		1514	# b) it allows us to delete the thunk later
		1515	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
		1516	};
		1517	}
		1518
		1519	# utility function to dup a filehandle. this is used by many backends
		1520	# to support binding more than one watcher per filehandle (they usually
		1521	# allow only one watcher per fd, so we dup it to get a different one).
		1522	sub _dupfh($$;$$) {
		1523	my ($poll, $fh, $r, $w) = @_;
		1524
		1525	# cygwin requires the fh mode to be matching, unix doesn't
		1526	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1527
		1528	open my $fh2, $mode, $fh
		1529	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1530
		1531	# we assume CLOEXEC is already set by perl in all important cases
		1532
		1533	($fh2, $rw)
		1534	}
		1535
		1536	=head1 SIMPLIFIED AE API
		1537
		1538	Starting with version 5.0, AnyEvent officially supports a second, much
		1539	simpler, API that is designed to reduce the calling, typing and memory
		1540	overhead by using function call syntax and a fixed number of parameters.
		1541
		1542	See the L<AE> manpage for details.
		1543
		1544	=cut
		1545
		1546	package AE;
		1547
		1548	our $VERSION = $AnyEvent::VERSION;
		1549
		1550	sub _reset() {
		1551	eval q{
		1552	# fall back to the main API by default - backends and AnyEvent::Base
		1553	# implementations can overwrite these.
		1554
		1555	sub io($$$) {
		1556	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1557	}
		1558
		1559	sub timer($$$) {
		1560	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1561	}
		1562
		1563	sub signal($$) {
		1564	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1565	}
		1566
		1567	sub child($$) {
		1568	AnyEvent->child (pid => $_[0], cb => $_[1])
		1569	}
		1570
		1571	sub idle($) {
		1572	AnyEvent->idle (cb => $_[0]);
		1573	}
		1574
		1575	sub cv(;&) {
		1576	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1577	}
		1578
		1579	sub now() {
		1580	AnyEvent->now
		1581	}
		1582
		1583	sub now_update() {
		1584	AnyEvent->now_update
		1585	}
		1586
		1587	sub time() {
		1588	AnyEvent->time
		1589	}
		1590
		1591	*postpone = \&AnyEvent::postpone;
		1592	*log = \&AnyEvent::log;
		1593	};
		1594	die if $@;
		1595	}
		1596
		1597	BEGIN { _reset }
		1598
		1599	package AnyEvent::Base;
		1600
		1601	# default implementations for many methods
		1602
		1603	sub time {
		1604	eval q{ # poor man's autoloading {}
		1605	# probe for availability of Time::HiRes
		1606	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1607	*time = sub { Time::HiRes::time () };
		1608	*AE::time = \& Time::HiRes::time ;
		1609	*now = \&time;
		1610	AnyEvent::log 8 => "AnyEvent: using Time::HiRes for sub-second timing accuracy.";
		1611	# if (eval "use POSIX (); (POSIX::times())...
		1612	} else {
		1613	*time = sub { CORE::time };
		1614	*AE::time = sub (){ CORE::time };
		1615	*now = \&time;
		1616	AnyEvent::log 3 => "using built-in time(), WARNING, no sub-second resolution!";
		1617	}
		1618	};
		1619	die if $@;
		1620
		1621	&time
		1622	}
		1623
		1624	*now = \&time;
		1625	sub now_update { }
		1626
		1627	sub _poll {
		1628	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1629	}
		1630
		1631	# default implementation for ->condvar
		1632	# in fact, the default should not be overwritten
		1633
		1634	sub condvar {
		1635	eval q{ # poor man's autoloading {}
		1636	*condvar = sub {
		1637	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1638	};
		1639
		1640	*AE::cv = sub (;&) {
		1641	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1642	};
		1643	};
		1644	die if $@;
		1645
		1646	&condvar
		1647	}
		1648
		1649	# default implementation for ->signal
		1650
		1651	our $HAVE_ASYNC_INTERRUPT;
		1652
		1653	sub _have_async_interrupt() {
		1654	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1655	&& eval "use Async::Interrupt 1.02 (); 1")
		1656	unless defined $HAVE_ASYNC_INTERRUPT;
		1657
		1658	$HAVE_ASYNC_INTERRUPT
		1659	}
		1660
		1661	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1662	our (%SIG_ASY, %SIG_ASY_W);
		1663	our ($SIG_COUNT, $SIG_TW);
		1664
		1665	# install a dummy wakeup watcher to reduce signal catching latency
		1666	# used by Impls
		1667	sub _sig_add() {
		1668	unless ($SIG_COUNT++) {
		1669	# try to align timer on a full-second boundary, if possible
		1670	my $NOW = AE::now;
		1671
		1672	$SIG_TW = AE::timer
		1673	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1674	$MAX_SIGNAL_LATENCY,
		1675	sub { } # just for the PERL_ASYNC_CHECK
		1676	;
		1677	}
		1678	}
		1679
		1680	sub _sig_del {
		1681	undef $SIG_TW
		1682	unless --$SIG_COUNT;
		1683	}
		1684
		1685	our $_sig_name_init; $_sig_name_init = sub {
		1686	eval q{ # poor man's autoloading {}
		1687	undef $_sig_name_init;
		1688
		1689	if (_have_async_interrupt) {
		1690	*sig2num = \&Async::Interrupt::sig2num;
		1691	*sig2name = \&Async::Interrupt::sig2name;
		1692	} else {
		1693	require Config;
		1694
		1695	my %signame2num;
		1696	@signame2num{ split ' ', $Config::Config{sig_name} }
		1697	= split ' ', $Config::Config{sig_num};
		1698
		1699	my @signum2name;
		1700	@signum2name[values %signame2num] = keys %signame2num;
		1701
		1702	*sig2num = sub($) {
		1703	$_[0] > 0 ? shift : $signame2num{+shift}
		1704	};
		1705	*sig2name = sub ($) {
		1706	$_[0] > 0 ? $signum2name[+shift] : shift
		1707	};
		1708	}
		1709	};
		1710	die if $@;
		1711	};
		1712
		1713	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1714	sub sig2name($) { &$_sig_name_init; &sig2name }
		1715
		1716	sub signal {
		1717	eval q{ # poor man's autoloading {}
		1718	# probe for availability of Async::Interrupt
		1719	if (_have_async_interrupt) {
		1720	AnyEvent::log 8 => "using Async::Interrupt for race-free signal handling.";
		1721
		1722	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1723	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1724
		1725	} else {
		1726	AnyEvent::log 8 => "using emulated perl signal handling with latency timer.";
		1727
		1728	if (AnyEvent::WIN32) {
		1729	require AnyEvent::Util;
		1730
		1731	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1732	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1733	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1734	} else {
		1735	pipe $SIGPIPE_R, $SIGPIPE_W;
		1736	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1737	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1738
		1739	# not strictly required, as $^F is normally 2, but let's make sure...
		1740	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1741	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1742	}
		1743
		1744	$SIGPIPE_R
		1745	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1746
		1747	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1748	}
		1749
		1750	*signal = $HAVE_ASYNC_INTERRUPT
		1751	? sub {
		1752	my (undef, %arg) = @_;
		1753
		1754	# async::interrupt
		1755	my $signal = sig2num $arg{signal};
		1756	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1757
		1758	$SIG_ASY{$signal} ||= new Async::Interrupt
		1759	cb => sub { undef $SIG_EV{$signal} },
		1760	signal => $signal,
		1761	pipe => [$SIGPIPE_R->filenos],
		1762	pipe_autodrain => 0,
		1763	;
		1764
		1765	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1766	}
		1767	: sub {
		1768	my (undef, %arg) = @_;
		1769
		1770	# pure perl
		1771	my $signal = sig2name $arg{signal};
		1772	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1773
		1774	$SIG{$signal} ||= sub {
909	last;	1775	local $!;
		1776	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1777	undef $SIG_EV{$signal};
910	}	1778	};
		1779
		1780	# can't do signal processing without introducing races in pure perl,
		1781	# so limit the signal latency.
		1782	_sig_add;
		1783
		1784	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1785	}
		1786	;
		1787
		1788	*AnyEvent::Base::signal::DESTROY = sub {
		1789	my ($signal, $cb) = @{$_[0]};
		1790
		1791	_sig_del;
		1792
		1793	delete $SIG_CB{$signal}{$cb};
		1794
		1795	$HAVE_ASYNC_INTERRUPT
		1796	? delete $SIG_ASY{$signal}
		1797	: # delete doesn't work with older perls - they then
		1798	# print weird messages, or just unconditionally exit
		1799	# instead of getting the default action.
		1800	undef $SIG{$signal}
		1801	unless keys %{ $SIG_CB{$signal} };
		1802	};
		1803
		1804	*_signal_exec = sub {
		1805	$HAVE_ASYNC_INTERRUPT
		1806	? $SIGPIPE_R->drain
		1807	: sysread $SIGPIPE_R, (my $dummy), 9;
		1808
		1809	while (%SIG_EV) {
		1810	for (keys %SIG_EV) {
		1811	delete $SIG_EV{$_};
		1812	&$_ for values %{ $SIG_CB{$_} || {} };
911	}	1813	}
912
913	$MODEL
914	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
915	}	1814	}
916	}	1815	};
917
918	unshift @ISA, $MODEL;
919	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
920
921	(shift @post_detect)->() while @post_detect;
922	}
923
924	$MODEL
925	}
926
927	sub AUTOLOAD {
928	(my $func = $AUTOLOAD) =~ s/.*://;
929
930	$method{$func}
931	or croak "$func: not a valid method for AnyEvent objects";
932
933	detect unless $MODEL;
934
935	my $class = shift;
936	$class->$func (@_);
937	}
938
939	package AnyEvent::Base;
940
941	# default implementation for now and time
942
943	use Time::HiRes ();
944
945	sub time { Time::HiRes::time }
946	sub now { Time::HiRes::time }
947
948	# default implementation for ->condvar
949
950	sub condvar {
951	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
952	}
953
954	# default implementation for ->signal
955
956	our %SIG_CB;
957
958	sub signal {
959	my (undef, %arg) = @_;
960
961	my $signal = uc $arg{signal}
962	or Carp::croak "required option 'signal' is missing";
963
964	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
965	$SIG{$signal} ||= sub {
966	$_->() for values %{ $SIG_CB{$signal} || {} };
967	};	1816	};
		1817	die if $@;
968		1818
969	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1819	&signal
970	}
971
972	sub AnyEvent::Base::Signal::DESTROY {
973	my ($signal, $cb) = @{$_[0]};
974
975	delete $SIG_CB{$signal}{$cb};
976
977	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
978	}	1820	}
979		1821
980	# default implementation for ->child	1822	# default implementation for ->child
981		1823
982	our %PID_CB;	1824	our %PID_CB;
983	our $CHLD_W;	1825	our $CHLD_W;
984	our $CHLD_DELAY_W;	1826	our $CHLD_DELAY_W;
985	our $PID_IDLE;
986	our $WNOHANG;
987		1827
988	sub _child_wait {	1828	# used by many Impl's
989	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1829	sub _emit_childstatus($$) {
		1830	my (undef, $rpid, $rstatus) = @_;
		1831
		1832	$_->($rpid, $rstatus)
990	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1833	for values %{ $PID_CB{$rpid} || {} },
991	(values %{ $PID_CB{0} || {} });	1834	values %{ $PID_CB{0} || {} };
992	}
993
994	undef $PID_IDLE;
995	}
996
997	sub _sigchld {
998	# make sure we deliver these changes "synchronous" with the event loop.
999	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1000	undef $CHLD_DELAY_W;
1001	&_child_wait;
1002	});
1003	}	1835	}
1004		1836
1005	sub child {	1837	sub child {
		1838	eval q{ # poor man's autoloading {}
		1839	*_sigchld = sub {
		1840	my $pid;
		1841
		1842	AnyEvent->_emit_childstatus ($pid, $?)
		1843	while ($pid = waitpid -1, WNOHANG) > 0;
		1844	};
		1845
		1846	*child = sub {
1006	my (undef, %arg) = @_;	1847	my (undef, %arg) = @_;
1007		1848
1008	defined (my $pid = $arg{pid} + 0)	1849	my $pid = $arg{pid};
1009	or Carp::croak "required option 'pid' is missing";	1850	my $cb = $arg{cb};
1010		1851
1011	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1852	$PID_CB{$pid}{$cb+0} = $cb;
1012		1853
1013	unless ($WNOHANG) {
1014	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1015	}
1016
1017	unless ($CHLD_W) {	1854	unless ($CHLD_W) {
1018	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1855	$CHLD_W = AE::signal CHLD => \&_sigchld;
1019	# child could be a zombie already, so make at least one round	1856	# child could be a zombie already, so make at least one round
1020	&_sigchld;	1857	&_sigchld;
1021	}	1858	}
1022		1859
1023	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1860	bless [$pid, $cb+0], "AnyEvent::Base::child"
1024	}	1861	};
1025		1862
1026	sub AnyEvent::Base::Child::DESTROY {	1863	*AnyEvent::Base::child::DESTROY = sub {
1027	my ($pid, $cb) = @{$_[0]};	1864	my ($pid, $icb) = @{$_[0]};
1028		1865
1029	delete $PID_CB{$pid}{$cb};	1866	delete $PID_CB{$pid}{$icb};
1030	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1867	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1031		1868
1032	undef $CHLD_W unless keys %PID_CB;	1869	undef $CHLD_W unless keys %PID_CB;
		1870	};
		1871	};
		1872	die if $@;
		1873
		1874	&child
		1875	}
		1876
		1877	# idle emulation is done by simply using a timer, regardless
		1878	# of whether the process is idle or not, and not letting
		1879	# the callback use more than 50% of the time.
		1880	sub idle {
		1881	eval q{ # poor man's autoloading {}
		1882	*idle = sub {
		1883	my (undef, %arg) = @_;
		1884
		1885	my ($cb, $w, $rcb) = $arg{cb};
		1886
		1887	$rcb = sub {
		1888	if ($cb) {
		1889	$w = AE::time;
		1890	&$cb;
		1891	$w = AE::time - $w;
		1892
		1893	# never use more then 50% of the time for the idle watcher,
		1894	# within some limits
		1895	$w = 0.0001 if $w < 0.0001;
		1896	$w = 5 if $w > 5;
		1897
		1898	$w = AE::timer $w, 0, $rcb;
		1899	} else {
		1900	# clean up...
		1901	undef $w;
		1902	undef $rcb;
		1903	}
		1904	};
		1905
		1906	$w = AE::timer 0.05, 0, $rcb;
		1907
		1908	bless \\$cb, "AnyEvent::Base::idle"
		1909	};
		1910
		1911	*AnyEvent::Base::idle::DESTROY = sub {
		1912	undef $${$_[0]};
		1913	};
		1914	};
		1915	die if $@;
		1916
		1917	&idle
1033	}	1918	}
1034		1919
1035	package AnyEvent::CondVar;	1920	package AnyEvent::CondVar;
1036		1921
1037	our @ISA = AnyEvent::CondVar::Base::;	1922	our @ISA = AnyEvent::CondVar::Base::;
1038		1923
		1924	# only to be used for subclassing
		1925	sub new {
		1926	my $class = shift;
		1927	bless AnyEvent->condvar (@_), $class
		1928	}
		1929
1039	package AnyEvent::CondVar::Base;	1930	package AnyEvent::CondVar::Base;
1040		1931
1041	use overload	1932	#use overload
1042	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1933	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1043	fallback => 1;	1934	# fallback => 1;
		1935
		1936	# save 300+ kilobytes by dirtily hardcoding overloading
		1937	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1938	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1939	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1940	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1941
		1942	our $WAITING;
1044		1943
1045	sub _send {	1944	sub _send {
1046	# nop	1945	# nop
		1946	}
		1947
		1948	sub _wait {
		1949	AnyEvent->_poll until $_[0]{_ae_sent};
1047	}	1950	}
1048		1951
1049	sub send {	1952	sub send {
1050	my $cv = shift;	1953	my $cv = shift;
1051	$cv->{_ae_sent} = [@_];	1954	$cv->{_ae_sent} = [@_];
…		…
1060		1963
1061	sub ready {	1964	sub ready {
1062	$_[0]{_ae_sent}	1965	$_[0]{_ae_sent}
1063	}	1966	}
1064		1967
1065	sub _wait {
1066	AnyEvent->one_event while !$_[0]{_ae_sent};
1067	}
1068
1069	sub recv {	1968	sub recv {
		1969	unless ($_[0]{_ae_sent}) {
		1970	$WAITING
		1971	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1972
		1973	local $WAITING = 1;
1070	$_[0]->_wait;	1974	$_[0]->_wait;
		1975	}
1071		1976
1072	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1977	$_[0]{_ae_croak}
1073	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1978	and Carp::croak $_[0]{_ae_croak};
		1979
		1980	wantarray
		1981	? @{ $_[0]{_ae_sent} }
		1982	: $_[0]{_ae_sent}[0]
1074	}	1983	}
1075		1984
1076	sub cb {	1985	sub cb {
1077	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1986	my $cv = shift;
		1987
		1988	@_
		1989	and $cv->{_ae_cb} = shift
		1990	and $cv->{_ae_sent}
		1991	and (delete $cv->{_ae_cb})->($cv);
		1992
1078	$_[0]{_ae_cb}	1993	$cv->{_ae_cb}
1079	}	1994	}
1080		1995
1081	sub begin {	1996	sub begin {
1082	++$_[0]{_ae_counter};	1997	++$_[0]{_ae_counter};
1083	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1998	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1088	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	2003	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1089	}	2004	}
1090		2005
1091	# undocumented/compatibility with pre-3.4	2006	# undocumented/compatibility with pre-3.4
1092	*broadcast = \&send;	2007	*broadcast = \&send;
1093	*wait = \&_wait;	2008	*wait = \&recv;
		2009
		2010	=head1 ERROR AND EXCEPTION HANDLING
		2011
		2012	In general, AnyEvent does not do any error handling - it relies on the
		2013	caller to do that if required. The L<AnyEvent::Strict> module (see also
		2014	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		2015	checking of all AnyEvent methods, however, which is highly useful during
		2016	development.
		2017
		2018	As for exception handling (i.e. runtime errors and exceptions thrown while
		2019	executing a callback), this is not only highly event-loop specific, but
		2020	also not in any way wrapped by this module, as this is the job of the main
		2021	program.
		2022
		2023	The pure perl event loop simply re-throws the exception (usually
		2024	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		2025	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		2026	so on.
		2027
		2028	=head1 ENVIRONMENT VARIABLES
		2029
		2030	AnyEvent supports a number of environment variables that tune the
		2031	runtime behaviour. They are usually evaluated when AnyEvent is
		2032	loaded, initialised, or a submodule that uses them is loaded. Many of
		2033	them also cause AnyEvent to load additional modules - for example,
		2034	C<PERL_ANYEVENT_DEBUG_WRAP> causes the L<AnyEvent::Debug> module to be
		2035	loaded.
		2036
		2037	All the environment variables documented here start with
		2038	C<PERL_ANYEVENT_>, which is what AnyEvent considers its own
		2039	namespace. Other modules are encouraged (but by no means required) to use
		2040	C<PERL_ANYEVENT_SUBMODULE> if they have registered the AnyEvent::Submodule
		2041	namespace on CPAN, for any submodule. For example, L<AnyEvent::HTTP> could
		2042	be expected to use C<PERL_ANYEVENT_HTTP_PROXY> (it should not access env
		2043	variables starting with C<AE_>, see below).
		2044
		2045	All variables can also be set via the C<AE_> prefix, that is, instead
		2046	of setting C<PERL_ANYEVENT_VERBOSE> you can also set C<AE_VERBOSE>. In
		2047	case there is a clash btween anyevent and another program that uses
		2048	C<AE_something> you can set the corresponding C<PERL_ANYEVENT_something>
		2049	variable to the empty string, as those variables take precedence.
		2050
		2051	When AnyEvent is first loaded, it copies all C<AE_xxx> env variables
		2052	to their C<PERL_ANYEVENT_xxx> counterpart unless that variable already
		2053	exists. If taint mode is on, then AnyEvent will remove I<all> environment
		2054	variables starting with C<PERL_ANYEVENT_> from C<%ENV> (or replace them
		2055	with C<undef> or the empty string, if the corresaponding C<AE_> variable
		2056	is set).
		2057
		2058	The exact algorithm is currently:
		2059
		2060	1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
		2061	2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
		2062	3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
		2063
		2064	This ensures that child processes will not see the C<AE_> variables.
		2065
		2066	The following environment variables are currently known to AnyEvent:
		2067
		2068	=over 4
		2069
		2070	=item C<PERL_ANYEVENT_VERBOSE>
		2071
		2072	By default, AnyEvent will only log messages with loglevel C<3>
		2073	(C<critical>) or higher (see L<AnyEvent::Log>). You can set this
		2074	environment variable to a numerical loglevel to make AnyEvent more (or
		2075	less) talkative.
		2076
		2077	If you want to do more than just set the global logging level
		2078	you should have a look at C<PERL_ANYEVENT_LOG>, which allows much more
		2079	complex specifications.
		2080
		2081	When set to C<0> (C<off>), then no messages whatsoever will be logged with
		2082	the default logging settings.
		2083
		2084	When set to C<5> or higher (C<warn>), causes AnyEvent to warn about
		2085	unexpected conditions, such as not being able to load the event model
		2086	specified by C<PERL_ANYEVENT_MODEL>, or a guard callback throwing an
		2087	exception - this is the minimum recommended level.
		2088
		2089	When set to C<7> or higher (info), cause AnyEvent to report which event model it
		2090	chooses.
		2091
		2092	When set to C<8> or higher (debug), then AnyEvent will report extra information on
		2093	which optional modules it loads and how it implements certain features.
		2094
		2095	=item C<PERL_ANYEVENT_LOG>
		2096
		2097	Accepts rather complex logging specifications. For example, you could log
		2098	all C<debug> messages of some module to stderr, warnings and above to
		2099	stderr, and errors and above to syslog, with:
		2100
		2101	PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
		2102
		2103	For the rather extensive details, see L<AnyEvent::Log>.
		2104
		2105	This variable is evaluated when AnyEvent (or L<AnyEvent::Log>) is loaded,
		2106	so will take effect even before AnyEvent has initialised itself.
		2107
		2108	Note that specifying this environment variable causes the L<AnyEvent::Log>
		2109	module to be loaded, while C<PERL_ANYEVENT_VERBOSE> does not, so only
		2110	using the latter saves a few hundred kB of memory until the first message
		2111	is being logged.
		2112
		2113	=item C<PERL_ANYEVENT_STRICT>
		2114
		2115	AnyEvent does not do much argument checking by default, as thorough
		2116	argument checking is very costly. Setting this variable to a true value
		2117	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		2118	check the arguments passed to most method calls. If it finds any problems,
		2119	it will croak.
		2120
		2121	In other words, enables "strict" mode.
		2122
		2123	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
		2124	>>, it is definitely recommended to keep it off in production. Keeping
		2125	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		2126	can be very useful, however.
		2127
		2128	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		2129
		2130	If this env variable is nonempty, then its contents will be interpreted by
		2131	C<AnyEvent::Socket::parse_hostport> and C<AnyEvent::Debug::shell> (after
		2132	replacing every occurance of C<$$> by the process pid). The shell object
		2133	is saved in C<$AnyEvent::Debug::SHELL>.
		2134
		2135	This happens when the first watcher is created.
		2136
		2137	For example, to bind a debug shell on a unix domain socket in
		2138	F<< /tmp/debug<pid>.sock >>, you could use this:
		2139
		2140	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		2141	# connect with e.g.: socat readline /tmp/debug123.sock
		2142
		2143	Or to bind to tcp port 4545 on localhost:
		2144
		2145	PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
		2146	# connect with e.g.: telnet localhost 4545
		2147
		2148	Note that creating sockets in F</tmp> or on localhost is very unsafe on
		2149	multiuser systems.
		2150
		2151	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2152
		2153	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2154	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
		2155
		2156	=item C<PERL_ANYEVENT_MODEL>
		2157
		2158	This can be used to specify the event model to be used by AnyEvent, before
		2159	auto detection and -probing kicks in.
		2160
		2161	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2162	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
		2163	resulting module name is loaded and - if the load was successful - used as
		2164	event model backend. If it fails to load then AnyEvent will proceed with
		2165	auto detection and -probing.
		2166
		2167	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2168	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2169	the end of a string designates a module name and quotes it appropriately).
		2170
		2171	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
		2172	could start your program like this:
		2173
		2174	PERL_ANYEVENT_MODEL=Perl perl ...
		2175
		2176	=item C<PERL_ANYEVENT_PROTOCOLS>
		2177
		2178	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		2179	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		2180	of auto probing).
		2181
		2182	Must be set to a comma-separated list of protocols or address families,
		2183	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		2184	used, and preference will be given to protocols mentioned earlier in the
		2185	list.
		2186
		2187	This variable can effectively be used for denial-of-service attacks
		2188	against local programs (e.g. when setuid), although the impact is likely
		2189	small, as the program has to handle conenction and other failures anyways.
		2190
		2191	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		2192	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		2193	- only support IPv4, never try to resolve or contact IPv6
		2194	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		2195	IPv6, but prefer IPv6 over IPv4.
		2196
		2197	=item C<PERL_ANYEVENT_HOSTS>
		2198
		2199	This variable, if specified, overrides the F</etc/hosts> file used by
		2200	L<AnyEvent::Socket>C<::resolve_sockaddr>, i.e. hosts aliases will be read
		2201	from that file instead.
		2202
		2203	=item C<PERL_ANYEVENT_EDNS0>
		2204
		2205	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension for
		2206	DNS. This extension is generally useful to reduce DNS traffic, especially
		2207	when DNSSEC is involved, but some (broken) firewalls drop such DNS
		2208	packets, which is why it is off by default.
		2209
		2210	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		2211	EDNS0 in its DNS requests.
		2212
		2213	=item C<PERL_ANYEVENT_MAX_FORKS>
		2214
		2215	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		2216	will create in parallel.
		2217
		2218	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2219
		2220	The default value for the C<max_outstanding> parameter for the default DNS
		2221	resolver - this is the maximum number of parallel DNS requests that are
		2222	sent to the DNS server.
		2223
		2224	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2225
		2226	The absolute path to a F<resolv.conf>-style file to use instead of
		2227	F</etc/resolv.conf> (or the OS-specific configuration) in the default
		2228	resolver, or the empty string to select the default configuration.
		2229
		2230	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2231
		2232	When neither C<ca_file> nor C<ca_path> was specified during
		2233	L<AnyEvent::TLS> context creation, and either of these environment
		2234	variables are nonempty, they will be used to specify CA certificate
		2235	locations instead of a system-dependent default.
		2236
		2237	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2238
		2239	When these are set to C<1>, then the respective modules are not
		2240	loaded. Mostly good for testing AnyEvent itself.
		2241
		2242	=back
1094		2243
1095	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2244	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1096		2245
1097	This is an advanced topic that you do not normally need to use AnyEvent in	2246	This is an advanced topic that you do not normally need to use AnyEvent in
1098	a module. This section is only of use to event loop authors who want to	2247	a module. This section is only of use to event loop authors who want to
…		…
1132		2281
1133	I<rxvt-unicode> also cheats a bit by not providing blocking access to	2282	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1134	condition variables: code blocking while waiting for a condition will	2283	condition variables: code blocking while waiting for a condition will
1135	C<die>. This still works with most modules/usages, and blocking calls must	2284	C<die>. This still works with most modules/usages, and blocking calls must
1136	not be done in an interactive application, so it makes sense.	2285	not be done in an interactive application, so it makes sense.
1137
1138	=head1 ENVIRONMENT VARIABLES
1139
1140	The following environment variables are used by this module:
1141
1142	=over 4
1143
1144	=item C<PERL_ANYEVENT_VERBOSE>
1145
1146	By default, AnyEvent will be completely silent except in fatal
1147	conditions. You can set this environment variable to make AnyEvent more
1148	talkative.
1149
1150	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1151	conditions, such as not being able to load the event model specified by
1152	C<PERL_ANYEVENT_MODEL>.
1153
1154	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1155	model it chooses.
1156
1157	=item C<PERL_ANYEVENT_MODEL>
1158
1159	This can be used to specify the event model to be used by AnyEvent, before
1160	auto detection and -probing kicks in. It must be a string consisting
1161	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1162	and the resulting module name is loaded and if the load was successful,
1163	used as event model. If it fails to load AnyEvent will proceed with
1164	auto detection and -probing.
1165
1166	This functionality might change in future versions.
1167
1168	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1169	could start your program like this:
1170
1171	PERL_ANYEVENT_MODEL=Perl perl ...
1172
1173	=item C<PERL_ANYEVENT_PROTOCOLS>
1174
1175	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1176	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1177	of auto probing).
1178
1179	Must be set to a comma-separated list of protocols or address families,
1180	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1181	used, and preference will be given to protocols mentioned earlier in the
1182	list.
1183
1184	This variable can effectively be used for denial-of-service attacks
1185	against local programs (e.g. when setuid), although the impact is likely
1186	small, as the program has to handle connection errors already-
1187
1188	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1189	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1190	- only support IPv4, never try to resolve or contact IPv6
1191	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1192	IPv6, but prefer IPv6 over IPv4.
1193
1194	=item C<PERL_ANYEVENT_EDNS0>
1195
1196	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1197	for DNS. This extension is generally useful to reduce DNS traffic, but
1198	some (broken) firewalls drop such DNS packets, which is why it is off by
1199	default.
1200
1201	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1202	EDNS0 in its DNS requests.
1203
1204	=item C<PERL_ANYEVENT_MAX_FORKS>
1205
1206	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1207	will create in parallel.
1208
1209	=back
1210		2286
1211	=head1 EXAMPLE PROGRAM	2287	=head1 EXAMPLE PROGRAM
1212		2288
1213	The following program uses an I/O watcher to read data from STDIN, a timer	2289	The following program uses an I/O watcher to read data from STDIN, a timer
1214	to display a message once per second, and a condition variable to quit the	2290	to display a message once per second, and a condition variable to quit the
…		…
1227	warn "read: $input\n"; # output what has been read	2303	warn "read: $input\n"; # output what has been read
1228	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2304	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1229	},	2305	},
1230	);	2306	);
1231		2307
1232	my $time_watcher; # can only be used once
1233
1234	sub new_timer {
1235	$timer = AnyEvent->timer (after => 1, cb => sub {	2308	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1236	warn "timeout\n"; # print 'timeout' about every second	2309	warn "timeout\n"; # print 'timeout' at most every second
1237	&new_timer; # and restart the time
1238	});	2310	});
1239	}
1240
1241	new_timer; # create first timer
1242		2311
1243	$cv->recv; # wait until user enters /^q/i	2312	$cv->recv; # wait until user enters /^q/i
1244		2313
1245	=head1 REAL-WORLD EXAMPLE	2314	=head1 REAL-WORLD EXAMPLE
1246		2315
…		…
1319		2388
1320	The actual code goes further and collects all errors (C<die>s, exceptions)	2389	The actual code goes further and collects all errors (C<die>s, exceptions)
1321	that occurred during request processing. The C<result> method detects	2390	that occurred during request processing. The C<result> method detects
1322	whether an exception as thrown (it is stored inside the $txn object)	2391	whether an exception as thrown (it is stored inside the $txn object)
1323	and just throws the exception, which means connection errors and other	2392	and just throws the exception, which means connection errors and other
1324	problems get reported tot he code that tries to use the result, not in a	2393	problems get reported to the code that tries to use the result, not in a
1325	random callback.	2394	random callback.
1326		2395
1327	All of this enables the following usage styles:	2396	All of this enables the following usage styles:
1328		2397
1329	1. Blocking:	2398	1. Blocking:
…		…
1377	through AnyEvent. The benchmark creates a lot of timers (with a zero	2446	through AnyEvent. The benchmark creates a lot of timers (with a zero
1378	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2447	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1379	which it is), lets them fire exactly once and destroys them again.	2448	which it is), lets them fire exactly once and destroys them again.
1380		2449
1381	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2450	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1382	distribution.	2451	distribution. It uses the L<AE> interface, which makes a real difference
		2452	for the EV and Perl backends only.
1383		2453
1384	=head3 Explanation of the columns	2454	=head3 Explanation of the columns
1385		2455
1386	I<watcher> is the number of event watchers created/destroyed. Since	2456	I<watcher> is the number of event watchers created/destroyed. Since
1387	different event models feature vastly different performances, each event	2457	different event models feature vastly different performances, each event
…		…
1408	watcher.	2478	watcher.
1409		2479
1410	=head3 Results	2480	=head3 Results
1411		2481
1412	name watchers bytes create invoke destroy comment	2482	name watchers bytes create invoke destroy comment
1413	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2483	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1414	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2484	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1415	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2485	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1416	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2486	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1417	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2487	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1418	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2488	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2489	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2490	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1419	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2491	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1420	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2492	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1421	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2493	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1422	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2494	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1423		2495
1424	=head3 Discussion	2496	=head3 Discussion
1425		2497
1426	The benchmark does I<not> measure scalability of the event loop very	2498	The benchmark does I<not> measure scalability of the event loop very
1427	well. For example, a select-based event loop (such as the pure perl one)	2499	well. For example, a select-based event loop (such as the pure perl one)
…		…
1439	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2511	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1440	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2512	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1441	cycles with POE.	2513	cycles with POE.
1442		2514
1443	C<EV> is the sole leader regarding speed and memory use, which are both	2515	C<EV> is the sole leader regarding speed and memory use, which are both
1444	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2516	maximal/minimal, respectively. When using the L<AE> API there is zero
		2517	overhead (when going through the AnyEvent API create is about 5-6 times
		2518	slower, with other times being equal, so still uses far less memory than
1445	far less memory than any other event loop and is still faster than Event	2519	any other event loop and is still faster than Event natively).
1446	natively.
1447		2520
1448	The pure perl implementation is hit in a few sweet spots (both the	2521	The pure perl implementation is hit in a few sweet spots (both the
1449	constant timeout and the use of a single fd hit optimisations in the perl	2522	constant timeout and the use of a single fd hit optimisations in the perl
1450	interpreter and the backend itself). Nevertheless this shows that it	2523	interpreter and the backend itself). Nevertheless this shows that it
1451	adds very little overhead in itself. Like any select-based backend its	2524	adds very little overhead in itself. Like any select-based backend its
1452	performance becomes really bad with lots of file descriptors (and few of	2525	performance becomes really bad with lots of file descriptors (and few of
1453	them active), of course, but this was not subject of this benchmark.	2526	them active), of course, but this was not subject of this benchmark.
1454		2527
1455	The C<Event> module has a relatively high setup and callback invocation	2528	The C<Event> module has a relatively high setup and callback invocation
1456	cost, but overall scores in on the third place.	2529	cost, but overall scores in on the third place.
		2530
		2531	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2532	when using its pure perl backend.
1457		2533
1458	C<Glib>'s memory usage is quite a bit higher, but it features a	2534	C<Glib>'s memory usage is quite a bit higher, but it features a
1459	faster callback invocation and overall ends up in the same class as	2535	faster callback invocation and overall ends up in the same class as
1460	C<Event>. However, Glib scales extremely badly, doubling the number of	2536	C<Event>. However, Glib scales extremely badly, doubling the number of
1461	watchers increases the processing time by more than a factor of four,	2537	watchers increases the processing time by more than a factor of four,
…		…
1496	(even when used without AnyEvent), but most event loops have acceptable	2572	(even when used without AnyEvent), but most event loops have acceptable
1497	performance with or without AnyEvent.	2573	performance with or without AnyEvent.
1498		2574
1499	=item * The overhead AnyEvent adds is usually much smaller than the overhead of	2575	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
1500	the actual event loop, only with extremely fast event loops such as EV	2576	the actual event loop, only with extremely fast event loops such as EV
1501	adds AnyEvent significant overhead.	2577	does AnyEvent add significant overhead.
1502		2578
1503	=item * You should avoid POE like the plague if you want performance or	2579	=item * You should avoid POE like the plague if you want performance or
1504	reasonable memory usage.	2580	reasonable memory usage.
1505		2581
1506	=back	2582	=back
…		…
1522	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2598	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1523	(1%) are active. This mirrors the activity of large servers with many	2599	(1%) are active. This mirrors the activity of large servers with many
1524	connections, most of which are idle at any one point in time.	2600	connections, most of which are idle at any one point in time.
1525		2601
1526	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2602	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1527	distribution.	2603	distribution. It uses the L<AE> interface, which makes a real difference
		2604	for the EV and Perl backends only.
1528		2605
1529	=head3 Explanation of the columns	2606	=head3 Explanation of the columns
1530		2607
1531	I<sockets> is the number of sockets, and twice the number of "servers" (as	2608	I<sockets> is the number of sockets, and twice the number of "servers" (as
1532	each server has a read and write socket end).	2609	each server has a read and write socket end).
…		…
1539	it to another server. This includes deleting the old timeout and creating	2616	it to another server. This includes deleting the old timeout and creating
1540	a new one that moves the timeout into the future.	2617	a new one that moves the timeout into the future.
1541		2618
1542	=head3 Results	2619	=head3 Results
1543		2620
1544	name sockets create request	2621	name sockets create request
1545	EV 20000 69.01 11.16	2622	EV 20000 62.66 7.99
1546	Perl 20000 73.32 35.87	2623	Perl 20000 68.32 32.64
1547	Event 20000 212.62 257.32	2624	IOAsync 20000 174.06 101.15 epoll
1548	Glib 20000 651.16 1896.30	2625	IOAsync 20000 174.67 610.84 poll
		2626	Event 20000 202.69 242.91
		2627	Glib 20000 557.01 1689.52
1549	POE 20000 349.67 12317.24 uses POE::Loop::Event	2628	POE 20000 341.54 12086.32 uses POE::Loop::Event
1550		2629
1551	=head3 Discussion	2630	=head3 Discussion
1552		2631
1553	This benchmark I<does> measure scalability and overall performance of the	2632	This benchmark I<does> measure scalability and overall performance of the
1554	particular event loop.	2633	particular event loop.
…		…
1556	EV is again fastest. Since it is using epoll on my system, the setup time	2635	EV is again fastest. Since it is using epoll on my system, the setup time
1557	is relatively high, though.	2636	is relatively high, though.
1558		2637
1559	Perl surprisingly comes second. It is much faster than the C-based event	2638	Perl surprisingly comes second. It is much faster than the C-based event
1560	loops Event and Glib.	2639	loops Event and Glib.
		2640
		2641	IO::Async performs very well when using its epoll backend, and still quite
		2642	good compared to Glib when using its pure perl backend.
1561		2643
1562	Event suffers from high setup time as well (look at its code and you will	2644	Event suffers from high setup time as well (look at its code and you will
1563	understand why). Callback invocation also has a high overhead compared to	2645	understand why). Callback invocation also has a high overhead compared to
1564	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2646	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1565	uses select or poll in basically all documented configurations.	2647	uses select or poll in basically all documented configurations.
…		…
1628	=item * C-based event loops perform very well with small number of	2710	=item * C-based event loops perform very well with small number of
1629	watchers, as the management overhead dominates.	2711	watchers, as the management overhead dominates.
1630		2712
1631	=back	2713	=back
1632		2714
		2715	=head2 THE IO::Lambda BENCHMARK
		2716
		2717	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2718	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2719	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2720	shouldn't come as a surprise to anybody). As such, the benchmark is
		2721	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2722	very optimal. But how would AnyEvent compare when used without the extra
		2723	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2724
		2725	The benchmark itself creates an echo-server, and then, for 500 times,
		2726	connects to the echo server, sends a line, waits for the reply, and then
		2727	creates the next connection. This is a rather bad benchmark, as it doesn't
		2728	test the efficiency of the framework or much non-blocking I/O, but it is a
		2729	benchmark nevertheless.
		2730
		2731	name runtime
		2732	Lambda/select 0.330 sec
		2733	+ optimized 0.122 sec
		2734	Lambda/AnyEvent 0.327 sec
		2735	+ optimized 0.138 sec
		2736	Raw sockets/select 0.077 sec
		2737	POE/select, components 0.662 sec
		2738	POE/select, raw sockets 0.226 sec
		2739	POE/select, optimized 0.404 sec
		2740
		2741	AnyEvent/select/nb 0.085 sec
		2742	AnyEvent/EV/nb 0.068 sec
		2743	+state machine 0.134 sec
		2744
		2745	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2746	benchmarks actually make blocking connects and use 100% blocking I/O,
		2747	defeating the purpose of an event-based solution. All of the newly
		2748	written AnyEvent benchmarks use 100% non-blocking connects (using
		2749	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2750	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2751	generally require a lot more bookkeeping and event handling than blocking
		2752	connects (which involve a single syscall only).
		2753
		2754	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2755	offers similar expressive power as POE and IO::Lambda, using conventional
		2756	Perl syntax. This means that both the echo server and the client are 100%
		2757	non-blocking, further placing it at a disadvantage.
		2758
		2759	As you can see, the AnyEvent + EV combination even beats the
		2760	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2761	backend easily beats IO::Lambda and POE.
		2762
		2763	And even the 100% non-blocking version written using the high-level (and
		2764	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2765	higher level ("unoptimised") abstractions by a large margin, even though
		2766	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2767
		2768	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2769	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2770	part of the IO::Lambda distribution and were used without any changes.
		2771
		2772
		2773	=head1 SIGNALS
		2774
		2775	AnyEvent currently installs handlers for these signals:
		2776
		2777	=over 4
		2778
		2779	=item SIGCHLD
		2780
		2781	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2782	emulation for event loops that do not support them natively. Also, some
		2783	event loops install a similar handler.
		2784
		2785	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2786	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2787
		2788	=item SIGPIPE
		2789
		2790	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2791	when AnyEvent gets loaded.
		2792
		2793	The rationale for this is that AnyEvent users usually do not really depend
		2794	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2795	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2796	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2797	some random socket.
		2798
		2799	The rationale for installing a no-op handler as opposed to ignoring it is
		2800	that this way, the handler will be restored to defaults on exec.
		2801
		2802	Feel free to install your own handler, or reset it to defaults.
		2803
		2804	=back
		2805
		2806	=cut
		2807
		2808	undef $SIG{CHLD}
		2809	if $SIG{CHLD} eq 'IGNORE';
		2810
		2811	$SIG{PIPE} = sub { }
		2812	unless defined $SIG{PIPE};
		2813
		2814	=head1 RECOMMENDED/OPTIONAL MODULES
		2815
		2816	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2817	its built-in modules) are required to use it.
		2818
		2819	That does not mean that AnyEvent won't take advantage of some additional
		2820	modules if they are installed.
		2821
		2822	This section explains which additional modules will be used, and how they
		2823	affect AnyEvent's operation.
		2824
		2825	=over 4
		2826
		2827	=item L<Async::Interrupt>
		2828
		2829	This slightly arcane module is used to implement fast signal handling: To
		2830	my knowledge, there is no way to do completely race-free and quick
		2831	signal handling in pure perl. To ensure that signals still get
		2832	delivered, AnyEvent will start an interval timer to wake up perl (and
		2833	catch the signals) with some delay (default is 10 seconds, look for
		2834	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2835
		2836	If this module is available, then it will be used to implement signal
		2837	catching, which means that signals will not be delayed, and the event loop
		2838	will not be interrupted regularly, which is more efficient (and good for
		2839	battery life on laptops).
		2840
		2841	This affects not just the pure-perl event loop, but also other event loops
		2842	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2843
		2844	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2845	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2846	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2847	does nothing for those backends.
		2848
		2849	=item L<EV>
		2850
		2851	This module isn't really "optional", as it is simply one of the backend
		2852	event loops that AnyEvent can use. However, it is simply the best event
		2853	loop available in terms of features, speed and stability: It supports
		2854	the AnyEvent API optimally, implements all the watcher types in XS, does
		2855	automatic timer adjustments even when no monotonic clock is available,
		2856	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2857	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2858	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2859
		2860	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2861	then this module will do nothing for you.
		2862
		2863	=item L<Guard>
		2864
		2865	The guard module, when used, will be used to implement
		2866	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2867	lot less memory), but otherwise doesn't affect guard operation much. It is
		2868	purely used for performance.
		2869
		2870	=item L<JSON> and L<JSON::XS>
		2871
		2872	One of these modules is required when you want to read or write JSON data
		2873	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2874	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2875
		2876	=item L<Net::SSLeay>
		2877
		2878	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2879	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2880	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2881
		2882	=item L<Time::HiRes>
		2883
		2884	This module is part of perl since release 5.008. It will be used when the
		2885	chosen event library does not come with a timing source of its own. The
		2886	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2887	try to use a monotonic clock for timing stability.
		2888
		2889	=back
		2890
1633		2891
1634	=head1 FORK	2892	=head1 FORK
1635		2893
1636	Most event libraries are not fork-safe. The ones who are usually are	2894	Most event libraries are not fork-safe. The ones who are usually are
1637	because they rely on inefficient but fork-safe C<select> or C<poll>	2895	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1638	calls. Only L<EV> is fully fork-aware.	2896	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2897	are usually badly thought-out hacks that are incompatible with fork in
		2898	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2899	continue event-processing in both parent and child (or both, if you know
		2900	what you are doing).
		2901
		2902	This means that, in general, you cannot fork and do event processing in
		2903	the child if the event library was initialised before the fork (which
		2904	usually happens when the first AnyEvent watcher is created, or the library
		2905	is loaded).
1639		2906
1640	If you have to fork, you must either do so I<before> creating your first	2907	If you have to fork, you must either do so I<before> creating your first
1641	watcher OR you must not use AnyEvent at all in the child.	2908	watcher OR you must not use AnyEvent at all in the child OR you must do
		2909	something completely out of the scope of AnyEvent.
		2910
		2911	The problem of doing event processing in the parent I<and> the child
		2912	is much more complicated: even for backends that I<are> fork-aware or
		2913	fork-safe, their behaviour is not usually what you want: fork clones all
		2914	watchers, that means all timers, I/O watchers etc. are active in both
		2915	parent and child, which is almost never what you want. USing C<exec>
		2916	to start worker children from some kind of manage rprocess is usually
		2917	preferred, because it is much easier and cleaner, at the expense of having
		2918	to have another binary.
1642		2919
1643		2920
1644	=head1 SECURITY CONSIDERATIONS	2921	=head1 SECURITY CONSIDERATIONS
1645		2922
1646	AnyEvent can be forced to load any event model via	2923	AnyEvent can be forced to load any event model via
…		…
1651	specified in the variable.	2928	specified in the variable.
1652		2929
1653	You can make AnyEvent completely ignore this variable by deleting it	2930	You can make AnyEvent completely ignore this variable by deleting it
1654	before the first watcher gets created, e.g. with a C<BEGIN> block:	2931	before the first watcher gets created, e.g. with a C<BEGIN> block:
1655		2932
1656	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2933	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1657		2934
1658	use AnyEvent;	2935	use AnyEvent;
1659		2936
1660	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2937	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1661	be used to probe what backend is used and gain other information (which is	2938	be used to probe what backend is used and gain other information (which is
1662	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2939	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2940	$ENV{PERL_ANYEVENT_STRICT}.
		2941
		2942	Note that AnyEvent will remove I<all> environment variables starting with
		2943	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2944	enabled.
		2945
		2946
		2947	=head1 BUGS
		2948
		2949	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2950	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2951	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2952	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2953	pronounced).
1663		2954
1664		2955
1665	=head1 SEE ALSO	2956	=head1 SEE ALSO
1666		2957
1667	Utility functions: L<AnyEvent::Util>.	2958	Tutorial/Introduction: L<AnyEvent::Intro>.
1668		2959
1669	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2960	FAQ: L<AnyEvent::FAQ>.
1670	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2961
		2962	Utility functions: L<AnyEvent::Util> (misc. grab-bag), L<AnyEvent::Log>
		2963	(simply logging).
		2964
		2965	Development/Debugging: L<AnyEvent::Strict> (stricter checking),
		2966	L<AnyEvent::Debug> (interactive shell, watcher tracing).
		2967
		2968	Supported event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>,
		2969	L<Glib::EV>, L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>,
		2970	L<Qt>, L<POE>, L<FLTK>.
1671		2971
1672	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2972	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1673	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2973	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1674	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2974	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
		2975	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>,
1675	L<AnyEvent::Impl::POE>.	2976	L<AnyEvent::Impl::FLTK>.
1676		2977
1677	Non-blocking file handles, sockets, TCP clients and	2978	Non-blocking handles, pipes, stream sockets, TCP clients and
1678	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2979	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1679		2980
1680	Asynchronous DNS: L<AnyEvent::DNS>.	2981	Asynchronous DNS: L<AnyEvent::DNS>.
1681		2982
1682	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2983	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1683		2984
1684	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2985	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2986	L<AnyEvent::HTTP>.
1685		2987
1686		2988
1687	=head1 AUTHOR	2989	=head1 AUTHOR
1688		2990
1689	Marc Lehmann <schmorp@schmorp.de>	2991	Marc Lehmann <schmorp@schmorp.de>
1690	http://home.schmorp.de/	2992	http://home.schmorp.de/
1691		2993
1692	=cut	2994	=cut
1693		2995
1694	1	2996	1
1695		2997

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