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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 and POE are various supported	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt,
6	event loops.	6	FLTK and POE are various supported event loops/environments.
7		7
8	=head1 SYNOPSIS	8	=head1 SYNOPSIS
9		9
10	use AnyEvent;	10	use AnyEvent;
11		11
		12	# if you prefer function calls, look at the AE manpage for
		13	# an alternative API.
		14
12	# file descriptor readable	15	# file handle or descriptor readable
13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
14		17
15	# one-shot or repeating timers	18	# one-shot or repeating timers
16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
18		21
19	print AnyEvent->now; # prints current event loop time	22	print AnyEvent->now; # prints current event loop time
20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
21		24
22	# POSIX signal	25	# POSIX signal
…		…
40	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
41		44
42	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
43	in a tutorial or some gentle introduction, have a look at the	46	in a tutorial or some gentle introduction, have a look at the
44	L<AnyEvent::Intro> manpage.	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.
45		58
46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
47		60
48	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
49	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
…		…
65	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
66	model you use.	79	model you use.
67		80
68	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
69	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
70	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
71	cannot use anything else, as they are simply incompatible to everything	84	cannot use anything else, as they are simply incompatible to everything
72	that isn't them. What's worse, all the potential users of your	85	that isn't them. What's worse, all the potential users of your
73	module are 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.
74		87
75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
76	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
77	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
78	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
79	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
80	event models it supports (including stuff like IO::Async, as long as those	93	supports (including stuff like IO::Async, as long as those use one of the
81	use one of the supported event loops. It is trivial to add new event loops	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
82	to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
83		96
84	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
85	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
86	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
87	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
88	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
89	technically possible.	102	technically possible.
90		103
91	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
92	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
98	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
99	model, you should I<not> use this module.	112	model, you should I<not> use this module.
100		113
101	=head1 DESCRIPTION	114	=head1 DESCRIPTION
102		115
103	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
104	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
105	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
106	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
107		120
108	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>
109	module.	122	module.
110		123
111	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
112	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
113	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
114	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
115	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
116	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
117	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
118	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
119	found, AnyEvent will fall back to a pure-perl event loop, which is not
120	very efficient, but should work everywhere.
121		132
122	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
123	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
124	that model the default. For example:	135	that model the default. For example:
125		136
…		…
127	use AnyEvent;	138	use AnyEvent;
128		139
129	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
130		141
131	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
132	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,
133	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
134		146
135	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
136	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
137	explicitly and enjoy the high availability of that event loop :)	149	availability of that event loop :)
138		150
139	=head1 WATCHERS	151	=head1 WATCHERS
140		152
141	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
142	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
…		…
147	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
148	is in control).	160	is in control).
149		161
150	Note that B<callbacks must not permanently change global variables>	162	Note that B<callbacks must not permanently change global variables>
151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<	163	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
152	callbacks must not C<die> >>. The former is good programming practise in	164	callbacks must not C<die> >>. The former is good programming practice in
153	Perl and the latter stems from the fact that exception handling differs	165	Perl and the latter stems from the fact that exception handling differs
154	widely between event loops.	166	widely between event loops.
155		167
156	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
157	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
158	to it).	170	to it).
159		171
160	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.
161		173
162	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
163	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.
164		176
165	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
166		178
167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
168	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
169	undef $w;	181	undef $w;
170	});	182	});
…		…
173	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
174	declared.	186	declared.
175		187
176	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
177		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
178	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
179	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
180		198
181	C<fh> is 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
182	for events (AnyEvent might or might not keep a reference to this file	200	for events (AnyEvent might or might not keep a reference to this file
183	handle). Note that only file handles pointing to things for which	201	handle). Note that only file handles pointing to things for which
184	non-blocking operation makes sense are allowed. This includes sockets,	202	non-blocking operation makes sense are allowed. This includes sockets,
185	most character devices, pipes, fifos and so on, but not for example files	203	most character devices, pipes, fifos and so on, but not for example files
186	or block devices.	204	or block devices.
…		…
196		214
197	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.
198	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
199	underlying file descriptor.	217	underlying file descriptor.
200		218
201	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
202	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
203	handles.	221	handles.
204		222
205	Example: wait for readability of STDIN, then read a line and disable the	223	Example: wait for readability of STDIN, then read a line and disable the
206	watcher.	224	watcher.
…		…
211	undef $w;	229	undef $w;
212	});	230	});
213		231
214	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
215		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
216	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 >>
217	method with the following mandatory arguments:	243	method with the following mandatory arguments:
218		244
219	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
220	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
…		…
222		248
223	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
224	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
225	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
226		252
227	The callback will normally be invoked once only. If you specify another	253	The callback will normally be invoked only once. If you specify another
228	parameter, C<interval>, as a strictly positive number (> 0), then the	254	parameter, C<interval>, as a strictly positive number (> 0), then the
229	callback will be invoked regularly at that interval (in fractional	255	callback will be invoked regularly at that interval (in fractional
230	seconds) after the first invocation. If C<interval> is specified with a	256	seconds) after the first invocation. If C<interval> is specified with a
231	false value, then it is treated as if it were missing.	257	false value, then it is treated as if it were not specified at all.
232		258
233	The callback will be rescheduled before invoking the callback, but no	259	The callback will be rescheduled before invoking the callback, but no
234	attempt is done to avoid timer drift in most backends, so the interval is	260	attempt is made to avoid timer drift in most backends, so the interval is
235	only approximate.	261	only approximate.
236		262
237	Example: fire an event after 7.7 seconds.	263	Example: fire an event after 7.7 seconds.
238		264
239	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
257		283
258	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
259	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
260	"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
261	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
262	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.
263		289
264	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
265	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
266	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)
267	timers.	293	timers.
268		294
269	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
270	AnyEvent API.	296	AnyEvent API.
…		…
292	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
293	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
294		320
295	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
296	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
297	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
298		324
299	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
300	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
301		327
302	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>
303	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
304		330
305	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
306	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
307	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
308	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
309	after three seconds.	335	after three seconds.
310		336
…		…
330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
331	account.	357	account.
332		358
333	=item AnyEvent->now_update	359	=item AnyEvent->now_update
334		360
335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache	361	Some event loops (such as L<EV> or L<AnyEvent::Loop>) cache the current
336	the current time for each loop iteration (see the discussion of L<<	362	time for each loop iteration (see the discussion of L<< AnyEvent->now >>,
337	AnyEvent->now >>, above).	363	above).
338		364
339	When a callback runs for a long time (or when the process sleeps), then	365	When a callback runs for a long time (or when the process sleeps), then
340	this "current" time will differ substantially from the real time, which	366	this "current" time will differ substantially from the real time, which
341	might affect timers and time-outs.	367	might affect timers and time-outs.
342		368
343	When this is the case, you can call this method, which will update the	369	When this is the case, you can call this method, which will update the
344	event loop's idea of "current time".	370	event loop's idea of "current time".
345		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
346	Note that updating the time I<might> cause some events to be handled.	379	Note that updating the time I<might> cause some events to be handled.
347		380
348	=back	381	=back
349		382
350	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
351		386
352	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
353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl	388	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
354	callback to be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
355		390
…		…
361	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
362	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,
363	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
364		399
365	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
366	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
367		403
368	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
369	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
370		407
371	Example: exit on SIGINT	408	Example: exit on SIGINT
372		409
373	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
374		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling)
		421	or "unsafe" (asynchronous) - the former might delay signal delivery
		422	indefinitely, the latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support
		432	attaching callbacks to signals in a generic way, which is a pity,
		433	as you cannot do race-free signal handling in perl, requiring
		434	C libraries for this. AnyEvent will try to do its best, which
		435	means in some cases, signals will be delayed. The maximum time
		436	a signal might be delayed is 10 seconds by default, but can
		437	be overriden via C<$ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY}> or
		438	C<$AnyEvent::MAX_SIGNAL_LATENCY> - see the L<ENVIRONMENT VARIABLES>
		439	section for details.
		440
		441	All these problems can be avoided by installing the optional
		442	L<Async::Interrupt> module, which works with most event loops. It will not
		443	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		444	(and not with L<POE> currently). For those, you just have to suffer the
		445	delays.
		446
375	=head2 CHILD PROCESS WATCHERS	447	=head2 CHILD PROCESS WATCHERS
376		448
		449	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		450
377	You can also watch on a child process exit and catch its exit status.	451	You can also watch for a child process exit and catch its exit status.
378		452
379	The child process is specified by the C<pid> argument (if set to C<0>, it	453	The child process is specified by the C<pid> argument (on some backends,
380	watches for any child process exit). The watcher will triggered only when	454	using C<0> watches for any child process exit, on others this will
381	the child process has finished and an exit status is available, not on	455	croak). The watcher will be triggered only when the child process has
382	any trace events (stopped/continued).	456	finished and an exit status is available, not on any trace events
		457	(stopped/continued).
383		458
384	The callback will be called with the pid and exit status (as returned by	459	The callback will be called with the pid and exit status (as returned by
385	waitpid), so unlike other watcher types, you I<can> rely on child watcher	460	waitpid), so unlike other watcher types, you I<can> rely on child watcher
386	callback arguments.	461	callback arguments.
387		462
…		…
392		467
393	There is a slight catch to child watchers, however: you usually start them	468	There is a slight catch to child watchers, however: you usually start them
394	I<after> the child process was created, and this means the process could	469	I<after> the child process was created, and this means the process could
395	have exited already (and no SIGCHLD will be sent anymore).	470	have exited already (and no SIGCHLD will be sent anymore).
396		471
397	Not all event models handle this correctly (POE doesn't), but even for	472	Not all event models handle this correctly (neither POE nor IO::Async do,
		473	see their AnyEvent::Impl manpages for details), but even for event models
398	event models that I<do> handle this correctly, they usually need to be	474	that I<do> handle this correctly, they usually need to be loaded before
399	loaded before the process exits (i.e. before you fork in the first place).	475	the process exits (i.e. before you fork in the first place). AnyEvent's
		476	pure perl event loop handles all cases correctly regardless of when you
		477	start the watcher.
400		478
401	This means you cannot create a child watcher as the very first thing in an	479	This means you cannot create a child watcher as the very first
402	AnyEvent program, you I<have> to create at least one watcher before you	480	thing in an AnyEvent program, you I<have> to create at least one
403	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	481	watcher before you C<fork> the child (alternatively, you can call
		482	C<AnyEvent::detect>).
		483
		484	As most event loops do not support waiting for child events, they will be
		485	emulated by AnyEvent in most cases, in which case the latency and race
		486	problems mentioned in the description of signal watchers apply.
404		487
405	Example: fork a process and wait for it	488	Example: fork a process and wait for it
406		489
407	my $done = AnyEvent->condvar;	490	my $done = AnyEvent->condvar;
408		491
…		…
420	# do something else, then wait for process exit	503	# do something else, then wait for process exit
421	$done->recv;	504	$done->recv;
422		505
423	=head2 IDLE WATCHERS	506	=head2 IDLE WATCHERS
424		507
425	Sometimes there is a need to do something, but it is not so important	508	$w = AnyEvent->idle (cb => <callback>);
426	to do it instantly, but only when there is nothing better to do. This
427	"nothing better to do" is usually defined to be "no other events need
428	attention by the event loop".
429		509
430	Idle watchers ideally get invoked when the event loop has nothing	510	This will repeatedly invoke the callback after the process becomes idle,
431	better to do, just before it would block the process to wait for new	511	until either the watcher is destroyed or new events have been detected.
432	events. Instead of blocking, the idle watcher is invoked.
433		512
434	Most event loops unfortunately do not really support idle watchers (only	513	Idle watchers are useful when there is a need to do something, but it
		514	is not so important (or wise) to do it instantly. The callback will be
		515	invoked only when there is "nothing better to do", which is usually
		516	defined as "all outstanding events have been handled and no new events
		517	have been detected". That means that idle watchers ideally get invoked
		518	when the event loop has just polled for new events but none have been
		519	detected. Instead of blocking to wait for more events, the idle watchers
		520	will be invoked.
		521
		522	Unfortunately, most event loops do not really support idle watchers (only
435	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent	523	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
436	will simply call the callback "from time to time".	524	will simply call the callback "from time to time".
437		525
438	Example: read lines from STDIN, but only process them when the	526	Example: read lines from STDIN, but only process them when the
439	program is otherwise idle:	527	program is otherwise idle:
…		…
455	});	543	});
456	});	544	});
457		545
458	=head2 CONDITION VARIABLES	546	=head2 CONDITION VARIABLES
459		547
		548	$cv = AnyEvent->condvar;
		549
		550	$cv->send (<list>);
		551	my @res = $cv->recv;
		552
460	If you are familiar with some event loops you will know that all of them	553	If you are familiar with some event loops you will know that all of them
461	require you to run some blocking "loop", "run" or similar function that	554	require you to run some blocking "loop", "run" or similar function that
462	will actively watch for new events and call your callbacks.	555	will actively watch for new events and call your callbacks.
463		556
464	AnyEvent is different, it expects somebody else to run the event loop and	557	AnyEvent is slightly different: it expects somebody else to run the event
465	will only block when necessary (usually when told by the user).	558	loop and will only block when necessary (usually when told by the user).
466		559
467	The instrument to do that is called a "condition variable", so called	560	The tool to do that is called a "condition variable", so called because
468	because they represent a condition that must become true.	561	they represent a condition that must become true.
		562
		563	Now is probably a good time to look at the examples further below.
469		564
470	Condition variables can be created by calling the C<< AnyEvent->condvar	565	Condition variables can be created by calling the C<< AnyEvent->condvar
471	>> method, usually without arguments. The only argument pair allowed is	566	>> method, usually without arguments. The only argument pair allowed is
472
473	C<cb>, which specifies a callback to be called when the condition variable	567	C<cb>, which specifies a callback to be called when the condition variable
474	becomes true, with the condition variable as the first argument (but not	568	becomes true, with the condition variable as the first argument (but not
475	the results).	569	the results).
476		570
477	After creation, the condition variable is "false" until it becomes "true"	571	After creation, the condition variable is "false" until it becomes "true"
478	by calling the C<send> method (or calling the condition variable as if it	572	by calling the C<send> method (or calling the condition variable as if it
479	were a callback, read about the caveats in the description for the C<<	573	were a callback, read about the caveats in the description for the C<<
480	->send >> method).	574	->send >> method).
481		575
482	Condition variables are similar to callbacks, except that you can	576	Since condition variables are the most complex part of the AnyEvent API, here are
483	optionally wait for them. They can also be called merge points - points	577	some different mental models of what they are - pick the ones you can connect to:
484	in time where multiple outstanding events have been processed. And yet	578
485	another way to call them is transactions - each condition variable can be	579	=over 4
486	used to represent a transaction, which finishes at some point and delivers	580
487	a result.	581	=item * Condition variables are like callbacks - you can call them (and pass them instead
		582	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		583
		584	=item * Condition variables are signals - one side can emit or send them,
		585	the other side can wait for them, or install a handler that is called when
		586	the signal fires.
		587
		588	=item * Condition variables are like "Merge Points" - points in your program
		589	where you merge multiple independent results/control flows into one.
		590
		591	=item * Condition variables represent a transaction - functions that start
		592	some kind of transaction can return them, leaving the caller the choice
		593	between waiting in a blocking fashion, or setting a callback.
		594
		595	=item * Condition variables represent future values, or promises to deliver
		596	some result, long before the result is available.
		597
		598	=back
488		599
489	Condition variables are very useful to signal that something has finished,	600	Condition variables are very useful to signal that something has finished,
490	for example, if you write a module that does asynchronous http requests,	601	for example, if you write a module that does asynchronous http requests,
491	then a condition variable would be the ideal candidate to signal the	602	then a condition variable would be the ideal candidate to signal the
492	availability of results. The user can either act when the callback is	603	availability of results. The user can either act when the callback is
…		…
505		616
506	Condition variables are represented by hash refs in perl, and the keys	617	Condition variables are represented by hash refs in perl, and the keys
507	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	618	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
508	easy (it is often useful to build your own transaction class on top of	619	easy (it is often useful to build your own transaction class on top of
509	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	620	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
510	it's C<new> method in your own C<new> method.	621	its C<new> method in your own C<new> method.
511		622
512	There are two "sides" to a condition variable - the "producer side" which	623	There are two "sides" to a condition variable - the "producer side" which
513	eventually calls C<< -> send >>, and the "consumer side", which waits	624	eventually calls C<< -> send >>, and the "consumer side", which waits
514	for the send to occur.	625	for the send to occur.
515		626
516	Example: wait for a timer.	627	Example: wait for a timer.
517		628
518	# wait till the result is ready	629	# condition: "wait till the timer is fired"
519	my $result_ready = AnyEvent->condvar;	630	my $timer_fired = AnyEvent->condvar;
520		631
521	# do something such as adding a timer	632	# create the timer - we could wait for, say
522	# or socket watcher the calls $result_ready->send	633	# a handle becomign ready, or even an
523	# when the "result" is ready.	634	# AnyEvent::HTTP request to finish, but
524	# in this case, we simply use a timer:	635	# in this case, we simply use a timer:
525	my $w = AnyEvent->timer (	636	my $w = AnyEvent->timer (
526	after => 1,	637	after => 1,
527	cb => sub { $result_ready->send },	638	cb => sub { $timer_fired->send },
528	);	639	);
529		640
530	# this "blocks" (while handling events) till the callback	641	# this "blocks" (while handling events) till the callback
531	# calls send	642	# calls ->send
532	$result_ready->recv;	643	$timer_fired->recv;
533		644
534	Example: wait for a timer, but take advantage of the fact that	645	Example: wait for a timer, but take advantage of the fact that condition
535	condition variables are also code references.	646	variables are also callable directly.
536		647
537	my $done = AnyEvent->condvar;	648	my $done = AnyEvent->condvar;
538	my $delay = AnyEvent->timer (after => 5, cb => $done);	649	my $delay = AnyEvent->timer (after => 5, cb => $done);
539	$done->recv;	650	$done->recv;
540		651
…		…
546		657
547	...	658	...
548		659
549	my @info = $couchdb->info->recv;	660	my @info = $couchdb->info->recv;
550		661
551	And this is how you would just ste a callback to be called whenever the	662	And this is how you would just set a callback to be called whenever the
552	results are available:	663	results are available:
553		664
554	$couchdb->info->cb (sub {	665	$couchdb->info->cb (sub {
555	my @info = $_[0]->recv;	666	my @info = $_[0]->recv;
556	});	667	});
…		…
574	immediately from within send.	685	immediately from within send.
575		686
576	Any arguments passed to the C<send> call will be returned by all	687	Any arguments passed to the C<send> call will be returned by all
577	future C<< ->recv >> calls.	688	future C<< ->recv >> calls.
578		689
579	Condition variables are overloaded so one can call them directly	690	Condition variables are overloaded so one can call them directly (as if
580	(as a code reference). Calling them directly is the same as calling	691	they were a code reference). Calling them directly is the same as calling
581	C<send>. Note, however, that many C-based event loops do not handle	692	C<send>.
582	overloading, so as tempting as it may be, passing a condition variable
583	instead of a callback does not work. Both the pure perl and EV loops
584	support overloading, however, as well as all functions that use perl to
585	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
586	example).
587		693
588	=item $cv->croak ($error)	694	=item $cv->croak ($error)
589		695
590	Similar to send, but causes all call's to C<< ->recv >> to invoke	696	Similar to send, but causes all calls to C<< ->recv >> to invoke
591	C<Carp::croak> with the given error message/object/scalar.	697	C<Carp::croak> with the given error message/object/scalar.
592		698
593	This can be used to signal any errors to the condition variable	699	This can be used to signal any errors to the condition variable
594	user/consumer.	700	user/consumer. Doing it this way instead of calling C<croak> directly
		701	delays the error detection, but has the overwhelming advantage that it
		702	diagnoses the error at the place where the result is expected, and not
		703	deep in some event callback with no connection to the actual code causing
		704	the problem.
595		705
596	=item $cv->begin ([group callback])	706	=item $cv->begin ([group callback])
597		707
598	=item $cv->end	708	=item $cv->end
599
600	These two methods are EXPERIMENTAL and MIGHT CHANGE.
601		709
602	These two methods can be used to combine many transactions/events into	710	These two methods can be used to combine many transactions/events into
603	one. For example, a function that pings many hosts in parallel might want	711	one. For example, a function that pings many hosts in parallel might want
604	to use a condition variable for the whole process.	712	to use a condition variable for the whole process.
605		713
606	Every call to C<< ->begin >> will increment a counter, and every call to	714	Every call to C<< ->begin >> will increment a counter, and every call to
607	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	715	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
608	>>, the (last) callback passed to C<begin> will be executed. That callback	716	>>, the (last) callback passed to C<begin> will be executed, passing the
609	is I<supposed> to call C<< ->send >>, but that is not required. If no	717	condvar as first argument. That callback is I<supposed> to call C<< ->send
610	callback was set, C<send> will be called without any arguments.	718	>>, but that is not required. If no group callback was set, C<send> will
		719	be called without any arguments.
611		720
612	Let's clarify this with the ping example:	721	You can think of C<< $cv->send >> giving you an OR condition (one call
		722	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		723	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		724
		725	Let's start with a simple example: you have two I/O watchers (for example,
		726	STDOUT and STDERR for a program), and you want to wait for both streams to
		727	close before activating a condvar:
613		728
614	my $cv = AnyEvent->condvar;	729	my $cv = AnyEvent->condvar;
615		730
		731	$cv->begin; # first watcher
		732	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		733	defined sysread $fh1, my $buf, 4096
		734	or $cv->end;
		735	});
		736
		737	$cv->begin; # second watcher
		738	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		739	defined sysread $fh2, my $buf, 4096
		740	or $cv->end;
		741	});
		742
		743	$cv->recv;
		744
		745	This works because for every event source (EOF on file handle), there is
		746	one call to C<begin>, so the condvar waits for all calls to C<end> before
		747	sending.
		748
		749	The ping example mentioned above is slightly more complicated, as the
		750	there are results to be passwd back, and the number of tasks that are
		751	begun can potentially be zero:
		752
		753	my $cv = AnyEvent->condvar;
		754
616	my %result;	755	my %result;
617	$cv->begin (sub { $cv->send (\%result) });	756	$cv->begin (sub { shift->send (\%result) });
618		757
619	for my $host (@list_of_hosts) {	758	for my $host (@list_of_hosts) {
620	$cv->begin;	759	$cv->begin;
621	ping_host_then_call_callback $host, sub {	760	ping_host_then_call_callback $host, sub {
622	$result{$host} = ...;	761	$result{$host} = ...;
…		…
624	};	763	};
625	}	764	}
626		765
627	$cv->end;	766	$cv->end;
628		767
		768	...
		769
		770	my $results = $cv->recv;
		771
629	This code fragment supposedly pings a number of hosts and calls	772	This code fragment supposedly pings a number of hosts and calls
630	C<send> after results for all then have have been gathered - in any	773	C<send> after results for all then have have been gathered - in any
631	order. To achieve this, the code issues a call to C<begin> when it starts	774	order. To achieve this, the code issues a call to C<begin> when it starts
632	each ping request and calls C<end> when it has received some result for	775	each ping request and calls C<end> when it has received some result for
633	it. Since C<begin> and C<end> only maintain a counter, the order in which	776	it. Since C<begin> and C<end> only maintain a counter, the order in which
…		…
637	loop, which serves two important purposes: first, it sets the callback	780	loop, which serves two important purposes: first, it sets the callback
638	to be called once the counter reaches C<0>, and second, it ensures that	781	to be called once the counter reaches C<0>, and second, it ensures that
639	C<send> is called even when C<no> hosts are being pinged (the loop	782	C<send> is called even when C<no> hosts are being pinged (the loop
640	doesn't execute once).	783	doesn't execute once).
641		784
642	This is the general pattern when you "fan out" into multiple subrequests:	785	This is the general pattern when you "fan out" into multiple (but
643	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	786	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
644	is called at least once, and then, for each subrequest you start, call	787	the callback and ensure C<end> is called at least once, and then, for each
645	C<begin> and for each subrequest you finish, call C<end>.	788	subrequest you start, call C<begin> and for each subrequest you finish,
		789	call C<end>.
646		790
647	=back	791	=back
648		792
649	=head3 METHODS FOR CONSUMERS	793	=head3 METHODS FOR CONSUMERS
650		794
…		…
654	=over 4	798	=over 4
655		799
656	=item $cv->recv	800	=item $cv->recv
657		801
658	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	802	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
659	>> methods have been called on c<$cv>, while servicing other watchers	803	>> methods have been called on C<$cv>, while servicing other watchers
660	normally.	804	normally.
661		805
662	You can only wait once on a condition - additional calls are valid but	806	You can only wait once on a condition - additional calls are valid but
663	will return immediately.	807	will return immediately.
664		808
…		…
666	function will call C<croak>.	810	function will call C<croak>.
667		811
668	In list context, all parameters passed to C<send> will be returned,	812	In list context, all parameters passed to C<send> will be returned,
669	in scalar context only the first one will be returned.	813	in scalar context only the first one will be returned.
670		814
		815	Note that doing a blocking wait in a callback is not supported by any
		816	event loop, that is, recursive invocation of a blocking C<< ->recv >> is
		817	not allowed and the C<recv> call will C<croak> if such a condition is
		818	detected. This requirement can be dropped by relying on L<Coro::AnyEvent>
		819	, which allows you to do a blocking C<< ->recv >> from any thread
		820	that doesn't run the event loop itself. L<Coro::AnyEvent> is loaded
		821	automatically when L<Coro> is used with L<AnyEvent>, so code does not need
		822	to do anything special to take advantage of that: any code that would
		823	normally block your program because it calls C<recv>, be executed in an
		824	C<async> thread instead without blocking other threads.
		825
671	Not all event models support a blocking wait - some die in that case	826	Not all event models support a blocking wait - some die in that case
672	(programs might want to do that to stay interactive), so I<if you are	827	(programs might want to do that to stay interactive), so I<if you are
673	using this from a module, never require a blocking wait>, but let the	828	using this from a module, never require a blocking wait>. Instead, let the
674	caller decide whether the call will block or not (for example, by coupling	829	caller decide whether the call will block or not (for example, by coupling
675	condition variables with some kind of request results and supporting	830	condition variables with some kind of request results and supporting
676	callbacks so the caller knows that getting the result will not block,	831	callbacks so the caller knows that getting the result will not block,
677	while still supporting blocking waits if the caller so desires).	832	while still supporting blocking waits if the caller so desires).
678		833
679	Another reason I<never> to C<< ->recv >> in a module is that you cannot
680	sensibly have two C<< ->recv >>'s in parallel, as that would require
681	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
682	can supply.
683
684	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
685	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
686	versions and also integrates coroutines into AnyEvent, making blocking
687	C<< ->recv >> calls perfectly safe as long as they are done from another
688	coroutine (one that doesn't run the event loop).
689
690	You can ensure that C<< -recv >> never blocks by setting a callback and	834	You can ensure that C<< ->recv >> never blocks by setting a callback and
691	only calling C<< ->recv >> from within that callback (or at a later	835	only calling C<< ->recv >> from within that callback (or at a later
692	time). This will work even when the event loop does not support blocking	836	time). This will work even when the event loop does not support blocking
693	waits otherwise.	837	waits otherwise.
694		838
695	=item $bool = $cv->ready	839	=item $bool = $cv->ready
…		…
701		845
702	This is a mutator function that returns the callback set and optionally	846	This is a mutator function that returns the callback set and optionally
703	replaces it before doing so.	847	replaces it before doing so.
704		848
705	The callback will be called when the condition becomes "true", i.e. when	849	The callback will be called when the condition becomes "true", i.e. when
706	C<send> or C<croak> are called, with the only argument being the condition	850	C<send> or C<croak> are called, with the only argument being the
707	variable itself. Calling C<recv> inside the callback or at any later time	851	condition variable itself. If the condition is already true, the
708	is guaranteed not to block.	852	callback is called immediately when it is set. Calling C<recv> inside
		853	the callback or at any later time is guaranteed not to block.
709		854
710	=back	855	=back
711		856
		857	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		858
		859	The available backend classes are (every class has its own manpage):
		860
		861	=over 4
		862
		863	=item Backends that are autoprobed when no other event loop can be found.
		864
		865	EV is the preferred backend when no other event loop seems to be in
		866	use. If EV is not installed, then AnyEvent will fall back to its own
		867	pure-perl implementation, which is available everywhere as it comes with
		868	AnyEvent itself.
		869
		870	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		871	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
		872
		873	=item Backends that are transparently being picked up when they are used.
		874
		875	These will be used if they are already loaded when the first watcher
		876	is created, in which case it is assumed that the application is using
		877	them. This means that AnyEvent will automatically pick the right backend
		878	when the main program loads an event module before anything starts to
		879	create watchers. Nothing special needs to be done by the main program.
		880
		881	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		882	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		883	AnyEvent::Impl::Tk based on Tk, very broken.
		884	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		885	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		886	AnyEvent::Impl::Irssi used when running within irssi.
		887	AnyEvent::Impl::IOAsync based on IO::Async.
		888	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		889	AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding).
		890
		891	=item Backends with special needs.
		892
		893	Qt requires the Qt::Application to be instantiated first, but will
		894	otherwise be picked up automatically. As long as the main program
		895	instantiates the application before any AnyEvent watchers are created,
		896	everything should just work.
		897
		898	AnyEvent::Impl::Qt based on Qt.
		899
		900	=item Event loops that are indirectly supported via other backends.
		901
		902	Some event loops can be supported via other modules:
		903
		904	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		905
		906	B<WxWidgets> has no support for watching file handles. However, you can
		907	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		908	polls 20 times per second, which was considered to be too horrible to even
		909	consider for AnyEvent.
		910
		911	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		912	backend, so it can be supported through POE.
		913
		914	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		915	load L<POE> when detecting them, in the hope that POE will pick them up,
		916	in which case everything will be automatic.
		917
		918	=back
		919
712	=head1 GLOBAL VARIABLES AND FUNCTIONS	920	=head1 GLOBAL VARIABLES AND FUNCTIONS
713		921
		922	These are not normally required to use AnyEvent, but can be useful to
		923	write AnyEvent extension modules.
		924
714	=over 4	925	=over 4
715		926
716	=item $AnyEvent::MODEL	927	=item $AnyEvent::MODEL
717		928
718	Contains C<undef> until the first watcher is being created. Then it	929	Contains C<undef> until the first watcher is being created, before the
		930	backend has been autodetected.
		931
719	contains the event model that is being used, which is the name of the	932	Afterwards it contains the event model that is being used, which is the
720	Perl class implementing the model. This class is usually one of the	933	name of the Perl class implementing the model. This class is usually one
721	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	934	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
722	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	935	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
723		936	will be C<urxvt::anyevent>).
724	The known classes so far are:
725
726	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
727	AnyEvent::Impl::Event based on Event, second best choice.
728	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
729	AnyEvent::Impl::Glib based on Glib, third-best choice.
730	AnyEvent::Impl::Tk based on Tk, very bad choice.
731	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
732	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
733	AnyEvent::Impl::POE based on POE, not generic enough for full support.
734
735	There is no support for WxWidgets, as WxWidgets has no support for
736	watching file handles. However, you can use WxWidgets through the
737	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
738	second, which was considered to be too horrible to even consider for
739	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
740	it's adaptor.
741
742	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
743	autodetecting them.
744		937
745	=item AnyEvent::detect	938	=item AnyEvent::detect
746		939
747	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	940	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
748	if necessary. You should only call this function right before you would	941	if necessary. You should only call this function right before you would
749	have created an AnyEvent watcher anyway, that is, as late as possible at	942	have created an AnyEvent watcher anyway, that is, as late as possible at
750	runtime.	943	runtime, and not e.g. during initialisation of your module.
		944
		945	The effect of calling this function is as if a watcher had been created
		946	(specifically, actions that happen "when the first watcher is created"
		947	happen when calling detetc as well).
		948
		949	If you need to do some initialisation before AnyEvent watchers are
		950	created, use C<post_detect>.
751		951
752	=item $guard = AnyEvent::post_detect { BLOCK }	952	=item $guard = AnyEvent::post_detect { BLOCK }
753		953
754	Arranges for the code block to be executed as soon as the event model is	954	Arranges for the code block to be executed as soon as the event model is
755	autodetected (or immediately if this has already happened).	955	autodetected (or immediately if that has already happened).
		956
		957	The block will be executed I<after> the actual backend has been detected
		958	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		959	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		960	other initialisations - see the sources of L<AnyEvent::Strict> or
		961	L<AnyEvent::AIO> to see how this is used.
		962
		963	The most common usage is to create some global watchers, without forcing
		964	event module detection too early, for example, L<AnyEvent::AIO> creates
		965	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		966	avoid autodetecting the event module at load time.
756		967
757	If called in scalar or list context, then it creates and returns an object	968	If called in scalar or list context, then it creates and returns an object
758	that automatically removes the callback again when it is destroyed. See	969	that automatically removes the callback again when it is destroyed (or
		970	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
759	L<Coro::BDB> for a case where this is useful.	971	a case where this is useful.
		972
		973	Example: Create a watcher for the IO::AIO module and store it in
		974	C<$WATCHER>, but do so only do so after the event loop is initialised.
		975
		976	our WATCHER;
		977
		978	my $guard = AnyEvent::post_detect {
		979	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		980	};
		981
		982	# the ||= is important in case post_detect immediately runs the block,
		983	# as to not clobber the newly-created watcher. assigning both watcher and
		984	# post_detect guard to the same variable has the advantage of users being
		985	# able to just C<undef $WATCHER> if the watcher causes them grief.
		986
		987	$WATCHER ||= $guard;
760		988
761	=item @AnyEvent::post_detect	989	=item @AnyEvent::post_detect
762		990
763	If there are any code references in this array (you can C<push> to it	991	If there are any code references in this array (you can C<push> to it
764	before or after loading AnyEvent), then they will called directly after	992	before or after loading AnyEvent), then they will be called directly
765	the event loop has been chosen.	993	after the event loop has been chosen.
766		994
767	You should check C<$AnyEvent::MODEL> before adding to this array, though:	995	You should check C<$AnyEvent::MODEL> before adding to this array, though:
768	if it contains a true value then the event loop has already been detected,	996	if it is defined then the event loop has already been detected, and the
769	and the array will be ignored.	997	array will be ignored.
770		998
771	Best use C<AnyEvent::post_detect { BLOCK }> instead.	999	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		1000	it, as it takes care of these details.
		1001
		1002	This variable is mainly useful for modules that can do something useful
		1003	when AnyEvent is used and thus want to know when it is initialised, but do
		1004	not need to even load it by default. This array provides the means to hook
		1005	into AnyEvent passively, without loading it.
		1006
		1007	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1008	together, you could put this into Coro (this is the actual code used by
		1009	Coro to accomplish this):
		1010
		1011	if (defined $AnyEvent::MODEL) {
		1012	# AnyEvent already initialised, so load Coro::AnyEvent
		1013	require Coro::AnyEvent;
		1014	} else {
		1015	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1016	# as soon as it is
		1017	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1018	}
		1019
		1020	=item AnyEvent::postpone { BLOCK }
		1021
		1022	Arranges for the block to be executed as soon as possible, but not before
		1023	the call itself returns. In practise, the block will be executed just
		1024	before the event loop polls for new events, or shortly afterwards.
		1025
		1026	This function never returns anything (to make the C<return postpone { ...
		1027	}> idiom more useful.
		1028
		1029	To understand the usefulness of this function, consider a function that
		1030	asynchronously does something for you and returns some transaction
		1031	object or guard to let you cancel the operation. For example,
		1032	C<AnyEvent::Socket::tcp_connect>:
		1033
		1034	# start a conenction attempt unless one is active
		1035	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1036	delete $self->{connect_guard};
		1037	...
		1038	};
		1039
		1040	Imagine that this function could instantly call the callback, for
		1041	example, because it detects an obvious error such as a negative port
		1042	number. Invoking the callback before the function returns causes problems
		1043	however: the callback will be called and will try to delete the guard
		1044	object. But since the function hasn't returned yet, there is nothing to
		1045	delete. When the function eventually returns it will assign the guard
		1046	object to C<< $self->{connect_guard} >>, where it will likely never be
		1047	deleted, so the program thinks it is still trying to connect.
		1048
		1049	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1050	callback directly on error:
		1051
		1052	$cb->(undef), return # signal error to callback, BAD!
		1053	if $some_error_condition;
		1054
		1055	It should use C<postpone>:
		1056
		1057	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1058	if $some_error_condition;
		1059
		1060	=item AnyEvent::log $level, $msg[, @args]
		1061
		1062	Log the given C<$msg> at the given C<$level>.
		1063
		1064	If L<AnyEvent::Log> is not loaded then this function makes a simple test
		1065	to see whether the message will be logged. If the test succeeds it will
		1066	load AnyEvent::Log and call C<AnyEvent::Log::log> - consequently, look at
		1067	the L<AnyEvent::Log> documentation for details.
		1068
		1069	If the test fails it will simply return. Right now this happens when a
		1070	numerical loglevel is used and it is larger than the level specified via
		1071	C<$ENV{PERL_ANYEVENT_VERBOSE}>.
		1072
		1073	If you want to sprinkle loads of logging calls around your code, consider
		1074	creating a logger callback with the C<AnyEvent::Log::logger> function,
		1075	which can reduce typing, codesize and can reduce the logging overhead
		1076	enourmously.
772		1077
773	=back	1078	=back
774		1079
775	=head1 WHAT TO DO IN A MODULE	1080	=head1 WHAT TO DO IN A MODULE
776		1081
…		…
787	because it will stall the whole program, and the whole point of using	1092	because it will stall the whole program, and the whole point of using
788	events is to stay interactive.	1093	events is to stay interactive.
789		1094
790	It is fine, however, to call C<< ->recv >> when the user of your module	1095	It is fine, however, to call C<< ->recv >> when the user of your module
791	requests it (i.e. if you create a http request object ad have a method	1096	requests it (i.e. if you create a http request object ad have a method
792	called C<results> that returns the results, it should call C<< ->recv >>	1097	called C<results> that returns the results, it may call C<< ->recv >>
793	freely, as the user of your module knows what she is doing. always).	1098	freely, as the user of your module knows what she is doing. Always).
794		1099
795	=head1 WHAT TO DO IN THE MAIN PROGRAM	1100	=head1 WHAT TO DO IN THE MAIN PROGRAM
796		1101
797	There will always be a single main program - the only place that should	1102	There will always be a single main program - the only place that should
798	dictate which event model to use.	1103	dictate which event model to use.
799		1104
800	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1105	If the program is not event-based, it need not do anything special, even
801	do anything special (it does not need to be event-based) and let AnyEvent	1106	when it depends on a module that uses an AnyEvent. If the program itself
802	decide which implementation to chose if some module relies on it.	1107	uses AnyEvent, but does not care which event loop is used, all it needs
		1108	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1109	available loop implementation.
803		1110
804	If the main program relies on a specific event model - for example, in	1111	If the main program relies on a specific event model - for example, in
805	Gtk2 programs you have to rely on the Glib module - you should load the	1112	Gtk2 programs you have to rely on the Glib module - you should load the
806	event module before loading AnyEvent or any module that uses it: generally	1113	event module before loading AnyEvent or any module that uses it: generally
807	speaking, you should load it as early as possible. The reason is that	1114	speaking, you should load it as early as possible. The reason is that
808	modules might create watchers when they are loaded, and AnyEvent will	1115	modules might create watchers when they are loaded, and AnyEvent will
809	decide on the event model to use as soon as it creates watchers, and it	1116	decide on the event model to use as soon as it creates watchers, and it
810	might chose the wrong one unless you load the correct one yourself.	1117	might choose the wrong one unless you load the correct one yourself.
811		1118
812	You can chose to use a pure-perl implementation by loading the	1119	You can chose to use a pure-perl implementation by loading the
813	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1120	C<AnyEvent::Loop> module, which gives you similar behaviour
814	everywhere, but letting AnyEvent chose the model is generally better.	1121	everywhere, but letting AnyEvent chose the model is generally better.
815		1122
816	=head2 MAINLOOP EMULATION	1123	=head2 MAINLOOP EMULATION
817		1124
818	Sometimes (often for short test scripts, or even standalone programs who	1125	Sometimes (often for short test scripts, or even standalone programs who
…		…
831		1138
832		1139
833	=head1 OTHER MODULES	1140	=head1 OTHER MODULES
834		1141
835	The following is a non-exhaustive list of additional modules that use	1142	The following is a non-exhaustive list of additional modules that use
836	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1143	AnyEvent as a client and can therefore be mixed easily with other
837	in the same program. Some of the modules come with AnyEvent, some are	1144	AnyEvent modules and other event loops in the same program. Some of the
838	available via CPAN.	1145	modules come as part of AnyEvent, the others are available via CPAN (see
		1146	L<http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for
		1147	a longer non-exhaustive list), and the list is heavily biased towards
		1148	modules of the AnyEvent author himself :)
839		1149
840	=over 4	1150	=over 4
841		1151
842	=item L<AnyEvent::Util>	1152	=item L<AnyEvent::Util>
843		1153
844	Contains various utility functions that replace often-used but blocking	1154	Contains various utility functions that replace often-used blocking
845	functions such as C<inet_aton> by event-/callback-based versions.	1155	functions such as C<inet_aton> with event/callback-based versions.
846		1156
847	=item L<AnyEvent::Socket>	1157	=item L<AnyEvent::Socket>
848		1158
849	Provides various utility functions for (internet protocol) sockets,	1159	Provides various utility functions for (internet protocol) sockets,
850	addresses and name resolution. Also functions to create non-blocking tcp	1160	addresses and name resolution. Also functions to create non-blocking tcp
…		…
852		1162
853	=item L<AnyEvent::Handle>	1163	=item L<AnyEvent::Handle>
854		1164
855	Provide read and write buffers, manages watchers for reads and writes,	1165	Provide read and write buffers, manages watchers for reads and writes,
856	supports raw and formatted I/O, I/O queued and fully transparent and	1166	supports raw and formatted I/O, I/O queued and fully transparent and
857	non-blocking SSL/TLS.	1167	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
858		1168
859	=item L<AnyEvent::DNS>	1169	=item L<AnyEvent::DNS>
860		1170
861	Provides rich asynchronous DNS resolver capabilities.	1171	Provides rich asynchronous DNS resolver capabilities.
862		1172
		1173	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1174
		1175	Implement event-based interfaces to the protocols of the same name (for
		1176	the curious, IGS is the International Go Server and FCP is the Freenet
		1177	Client Protocol).
		1178
863	=item L<AnyEvent::HTTP>	1179	=item L<AnyEvent::AIO>
864		1180
865	A simple-to-use HTTP library that is capable of making a lot of concurrent	1181	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
866	HTTP requests.	1182	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1183	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1184	file I/O, and much more.
		1185
		1186	=item L<AnyEvent::Filesys::Notify>
		1187
		1188	AnyEvent is good for non-blocking stuff, but it can't detect file or
		1189	path changes (e.g. "watch this directory for new files", "watch this
		1190	file for changes"). The L<AnyEvent::Filesys::Notify> module promises to
		1191	do just that in a portbale fashion, supporting inotify on GNU/Linux and
		1192	some weird, without doubt broken, stuff on OS X to monitor files. It can
		1193	fall back to blocking scans at regular intervals transparently on other
		1194	platforms, so it's about as portable as it gets.
		1195
		1196	(I haven't used it myself, but I haven't heard anybody complaining about
		1197	it yet).
		1198
		1199	=item L<AnyEvent::DBI>
		1200
		1201	Executes L<DBI> requests asynchronously in a proxy process for you,
		1202	notifying you in an event-based way when the operation is finished.
867		1203
868	=item L<AnyEvent::HTTPD>	1204	=item L<AnyEvent::HTTPD>
869		1205
870	Provides a simple web application server framework.	1206	A simple embedded webserver.
871		1207
872	=item L<AnyEvent::FastPing>	1208	=item L<AnyEvent::FastPing>
873		1209
874	The fastest ping in the west.	1210	The fastest ping in the west.
875		1211
876	=item L<AnyEvent::DBI>
877
878	Executes L<DBI> requests asynchronously in a proxy process.
879
880	=item L<AnyEvent::AIO>
881
882	Truly asynchronous I/O, should be in the toolbox of every event
883	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
884	together.
885
886	=item L<AnyEvent::BDB>
887
888	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
889	L<BDB> and AnyEvent together.
890
891	=item L<AnyEvent::GPSD>
892
893	A non-blocking interface to gpsd, a daemon delivering GPS information.
894
895	=item L<AnyEvent::IGS>
896
897	A non-blocking interface to the Internet Go Server protocol (used by
898	L<App::IGS>).
899
900	=item L<AnyEvent::IRC>
901
902	AnyEvent based IRC client module family (replacing the older Net::IRC3).
903
904	=item L<Net::XMPP2>
905
906	AnyEvent based XMPP (Jabber protocol) module family.
907
908	=item L<Net::FCP>
909
910	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
911	of AnyEvent.
912
913	=item L<Event::ExecFlow>
914
915	High level API for event-based execution flow control.
916
917	=item L<Coro>	1212	=item L<Coro>
918		1213
919	Has special support for AnyEvent via L<Coro::AnyEvent>.	1214	Has special support for AnyEvent via L<Coro::AnyEvent>, which allows you
		1215	to simply invert the flow control - don't call us, we will call you:
920		1216
921	=item L<IO::Lambda>	1217	async {
		1218	Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
		1219	print "5 seconds later!\n";
922		1220
923	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	1221	Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
		1222	my $line = <STDIN>; # works for ttys
		1223
		1224	AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
		1225	my ($body, $hdr) = Coro::rouse_wait;
		1226	};
924		1227
925	=back	1228	=back
926		1229
927	=cut	1230	=cut
928		1231
929	package AnyEvent;	1232	package AnyEvent;
930		1233
931	no warnings;	1234	# basically a tuned-down version of common::sense
932	use strict qw(vars subs);	1235	sub common_sense {
		1236	# from common:.sense 3.5
		1237	local $^W;
		1238	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1239	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1240	$^H |= 0x00000600;
		1241	}
933		1242
		1243	BEGIN { AnyEvent::common_sense }
		1244
934	use Carp;	1245	use Carp ();
935		1246
936	our $VERSION = 4.411;	1247	our $VERSION = '7.04';
937	our $MODEL;	1248	our $MODEL;
938
939	our $AUTOLOAD;
940	our @ISA;	1249	our @ISA;
941
942	our @REGISTRY;	1250	our @REGISTRY;
943		1251	our $VERBOSE;
944	our $WIN32;	1252	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		1253	our $MAX_SIGNAL_LATENCY = $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} || 10; # executes after the BEGIN block below (tainting!)
945		1254
946	BEGIN {	1255	BEGIN {
947	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";	1256	require "AnyEvent/constants.pl";
		1257
948	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";	1258	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
949		1259
950	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}	1260	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
951	if ${^TAINT};	1261	if ${^TAINT};
952	}
953		1262
954	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1263	$ENV{"PERL_ANYEVENT_$_"} = $ENV{"AE_$_"}
		1264	for grep s/^AE_// && !exists $ENV{"PERL_ANYEVENT_$_"}, keys %ENV;
955		1265
956	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1266	@ENV{grep /^PERL_ANYEVENT_/, keys %ENV} = ()
		1267	if ${^TAINT};
957		1268
958	{	1269	# $ENV{PERL_ANYEVENT_xxx} now valid
		1270
		1271	$VERBOSE = length $ENV{PERL_ANYEVENT_VERBOSE} ? $ENV{PERL_ANYEVENT_VERBOSE}*1 : 4;
		1272
959	my $idx;	1273	my $idx;
960	$PROTOCOL{$_} = ++$idx	1274	$PROTOCOL{$_} = ++$idx
961	for reverse split /\s*,\s*/,	1275	for reverse split /\s*,\s*/,
962	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1276	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
963	}	1277	}
964		1278
		1279	our @post_detect;
		1280
		1281	sub post_detect(&) {
		1282	my ($cb) = @_;
		1283
		1284	push @post_detect, $cb;
		1285
		1286	defined wantarray
		1287	? bless \$cb, "AnyEvent::Util::postdetect"
		1288	: ()
		1289	}
		1290
		1291	sub AnyEvent::Util::postdetect::DESTROY {
		1292	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1293	}
		1294
		1295	our $POSTPONE_W;
		1296	our @POSTPONE;
		1297
		1298	sub _postpone_exec {
		1299	undef $POSTPONE_W;
		1300
		1301	&{ shift @POSTPONE }
		1302	while @POSTPONE;
		1303	}
		1304
		1305	sub postpone(&) {
		1306	push @POSTPONE, shift;
		1307
		1308	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1309
		1310	()
		1311	}
		1312
		1313	sub log($$;@) {
		1314	# only load the big bloated module when we actually are about to log something
		1315	if ($_[0] <= ($VERBOSE || 1)) { # also catches non-numeric levels(!) and fatal
		1316	local ($!, $@);
		1317	require AnyEvent::Log; # among other things, sets $VERBOSE to 9
		1318	# AnyEvent::Log overwrites this function
		1319	goto &log;
		1320	}
		1321
		1322	0 # not logged
		1323	}
		1324
		1325	sub _logger($;$) {
		1326	my ($level, $renabled) = @_;
		1327
		1328	$$renabled = $level <= $VERBOSE;
		1329
		1330	my $logger = [(caller)[0], $level, $renabled];
		1331
		1332	$AnyEvent::Log::LOGGER{$logger+0} = $logger;
		1333
		1334	# return unless defined wantarray;
		1335	#
		1336	# require AnyEvent::Util;
		1337	# my $guard = AnyEvent::Util::guard (sub {
		1338	# # "clean up"
		1339	# delete $LOGGER{$logger+0};
		1340	# });
		1341	#
		1342	# sub {
		1343	# return 0 unless $$renabled;
		1344	#
		1345	# $guard if 0; # keep guard alive, but don't cause runtime overhead
		1346	# require AnyEvent::Log unless $AnyEvent::Log::VERSION;
		1347	# package AnyEvent::Log;
		1348	# _log ($logger->[0], $level, @_) # logger->[0] has been converted at load time
		1349	# }
		1350	}
		1351
		1352	if (length $ENV{PERL_ANYEVENT_LOG}) {
		1353	require AnyEvent::Log; # AnyEvent::Log does the thing for us
		1354	}
		1355
965	my @models = (	1356	our @models = (
966	[EV:: => AnyEvent::Impl::EV::],	1357	[EV:: => AnyEvent::Impl::EV::],
967	[Event:: => AnyEvent::Impl::Event::],
968	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1358	[AnyEvent::Loop:: => AnyEvent::Impl::Perl::],
969	# everything below here will not be autoprobed	1359	# everything below here will not (normally) be autoprobed
970	# as the pureperl backend should work everywhere	1360	# as the pure perl backend should work everywhere
971	# and is usually faster	1361	# and is usually faster
		1362	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package, so msut be near the top
		1363	[Event:: => AnyEvent::Impl::Event::], # slow, stable
		1364	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1365	# everything below here should not be autoloaded
		1366	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
972	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1367	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
973	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
974	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
975	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1368	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
976	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1369	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
977	[Wx:: => AnyEvent::Impl::POE::],	1370	[Wx:: => AnyEvent::Impl::POE::],
978	[Prima:: => AnyEvent::Impl::POE::],	1371	[Prima:: => AnyEvent::Impl::POE::],
		1372	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1373	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1374	[FLTK:: => AnyEvent::Impl::FLTK::],
979	);	1375	);
980		1376
981	our %method = map +($_ => 1),	1377	our @isa_hook;
		1378
		1379	sub _isa_set {
		1380	my @pkg = ("AnyEvent", (map $_->[0], grep defined, @isa_hook), $MODEL);
		1381
		1382	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1383	for 1 .. $#pkg;
		1384
		1385	grep $_ && $_->[1], @isa_hook
		1386	and AE::_reset ();
		1387	}
		1388
		1389	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1390	sub _isa_hook($$;$) {
		1391	my ($i, $pkg, $reset_ae) = @_;
		1392
		1393	$isa_hook[$i] = $pkg ? [$pkg, $reset_ae] : undef;
		1394
		1395	_isa_set;
		1396	}
		1397
		1398	# all autoloaded methods reserve the complete glob, not just the method slot.
		1399	# due to bugs in perls method cache implementation.
982	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1400	our @methods = qw(io timer time now now_update signal child idle condvar);
983		1401
984	our @post_detect;
985
986	sub post_detect(&) {	1402	sub detect() {
987	my ($cb) = @_;	1403	return $MODEL if $MODEL; # some programs keep references to detect
988		1404
989	if ($MODEL) {	1405	# IO::Async::Loop::AnyEvent is extremely evil, refuse to work with it
990	$cb->();	1406	# the author knows about the problems and what it does to AnyEvent as a whole
		1407	# (and the ability of others to use AnyEvent), but simply wants to abuse AnyEvent
		1408	# anyway.
		1409	AnyEvent::log fatal => "IO::Async::Loop::AnyEvent detected - that module is broken by\n"
		1410	. "design, abuses internals and breaks AnyEvent - will not continue."
		1411	if exists $INC{"IO/Async/Loop/AnyEvent.pm"};
991		1412
992	1	1413	local $!; # for good measure
		1414	local $SIG{__DIE__}; # we use eval
		1415
		1416	# free some memory
		1417	*detect = sub () { $MODEL };
		1418	# undef &func doesn't correctly update the method cache. grmbl.
		1419	# so we delete the whole glob. grmbl.
		1420	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1421	# a glob with an active sub. hrm. i hope it works, but perl is
		1422	# usually buggy in this department. sigh.
		1423	delete @{"AnyEvent::"}{@methods};
		1424	undef @methods;
		1425
		1426	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1427	my $model = $1;
		1428	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1429	if (eval "require $model") {
		1430	AnyEvent::log 7 => "Loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.";
		1431	$MODEL = $model;
993	} else {	1432	} else {
994	push @post_detect, $cb;	1433	AnyEvent::log 4 => "Unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
995		1434	}
996	defined wantarray
997	? bless \$cb, "AnyEvent::Util::postdetect"
998	: ()
999	}	1435	}
1000	}
1001		1436
1002	sub AnyEvent::Util::postdetect::DESTROY {	1437	# check for already loaded models
1003	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1004	}
1005
1006	sub detect() {
1007	unless ($MODEL) {	1438	unless ($MODEL) {
1008	no strict 'refs';	1439	for (@REGISTRY, @models) {
1009	local $SIG{__DIE__};	1440	my ($package, $model) = @$_;
1010		1441	if (${"$package\::VERSION"} > 0) {
1011	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1012	my $model = "AnyEvent::Impl::$1";
1013	if (eval "require $model") {	1442	if (eval "require $model") {
		1443	AnyEvent::log 7 => "Autodetected model '$model', using it.";
1014	$MODEL = $model;	1444	$MODEL = $model;
1015	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1445	last;
1016	} else {	1446	} else {
1017	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1447	AnyEvent::log 8 => "Detected event loop $package, but cannot load '$model', skipping: $@";
		1448	}
1018	}	1449	}
1019	}	1450	}
1020		1451
1021	# check for already loaded models
1022	unless ($MODEL) {	1452	unless ($MODEL) {
		1453	# try to autoload a model
1023	for (@REGISTRY, @models) {	1454	for (@REGISTRY, @models) {
1024	my ($package, $model) = @$_;	1455	my ($package, $model) = @$_;
		1456	if (
		1457	eval "require $package"
1025	if (${"$package\::VERSION"} > 0) {	1458	and ${"$package\::VERSION"} > 0
1026	if (eval "require $model") {	1459	and eval "require $model"
		1460	) {
		1461	AnyEvent::log 7 => "Autoloaded model '$model', using it.";
1027	$MODEL = $model;	1462	$MODEL = $model;
1028	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
1029	last;	1463	last;
1030	}
1031	}	1464	}
1032	}	1465	}
1033		1466
1034	unless ($MODEL) {
1035	# try to load a model
1036
1037	for (@REGISTRY, @models) {
1038	my ($package, $model) = @$_;
1039	if (eval "require $package"
1040	and ${"$package\::VERSION"} > 0
1041	and eval "require $model") {
1042	$MODEL = $model;
1043	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
1044	last;
1045	}
1046	}
1047
1048	$MODEL	1467	$MODEL
1049	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";	1468	or AnyEvent::log fatal => "Backend autodetection failed - did you properly install AnyEvent?";
1050	}
1051	}	1469	}
1052
1053	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1054
1055	unshift @ISA, $MODEL;
1056
1057	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1058
1059	(shift @post_detect)->() while @post_detect;
1060	}	1470	}
1061		1471
		1472	# free memory only needed for probing
		1473	undef @models;
		1474	undef @REGISTRY;
		1475
		1476	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1477
		1478	# now nuke some methods that are overridden by the backend.
		1479	# SUPER usage is not allowed in these.
		1480	for (qw(time signal child idle)) {
		1481	undef &{"AnyEvent::Base::$_"}
		1482	if defined &{"$MODEL\::$_"};
		1483	}
		1484
		1485	_isa_set;
		1486
		1487	# we're officially open!
		1488
		1489	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1490	require AnyEvent::Strict;
		1491	}
		1492
		1493	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1494	require AnyEvent::Debug;
		1495	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1496	}
		1497
		1498	if (length $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1499	require AnyEvent::Socket;
		1500	require AnyEvent::Debug;
		1501
		1502	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1503	$shell =~ s/\$\$/$$/g;
		1504
		1505	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1506	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1507	}
		1508
		1509	# now the anyevent environment is set up as the user told us to, so
		1510	# call the actual user code - post detects
		1511
		1512	(shift @post_detect)->() while @post_detect;
		1513	undef @post_detect;
		1514
		1515	*post_detect = sub(&) {
		1516	shift->();
		1517
		1518	undef
		1519	};
		1520
1062	$MODEL	1521	$MODEL
1063	}	1522	}
1064		1523
1065	sub AUTOLOAD {	1524	for my $name (@methods) {
1066	(my $func = $AUTOLOAD) =~ s/.*://;	1525	*$name = sub {
1067		1526	detect;
1068	$method{$func}	1527	# we use goto because
1069	or croak "$func: not a valid method for AnyEvent objects";	1528	# a) it makes the thunk more transparent
1070		1529	# b) it allows us to delete the thunk later
1071	detect unless $MODEL;	1530	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
1072		1531	};
1073	my $class = shift;
1074	$class->$func (@_);
1075	}	1532	}
1076		1533
1077	# utility function to dup a filehandle. this is used by many backends	1534	# utility function to dup a filehandle. this is used by many backends
1078	# to support binding more than one watcher per filehandle (they usually	1535	# to support binding more than one watcher per filehandle (they usually
1079	# allow only one watcher per fd, so we dup it to get a different one).	1536	# allow only one watcher per fd, so we dup it to get a different one).
1080	sub _dupfh($$$$) {	1537	sub _dupfh($$;$$) {
1081	my ($poll, $fh, $r, $w) = @_;	1538	my ($poll, $fh, $r, $w) = @_;
1082		1539
1083	# cygwin requires the fh mode to be matching, unix doesn't	1540	# cygwin requires the fh mode to be matching, unix doesn't
1084	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1541	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1085	: $poll eq "w" ? ($w, ">")
1086	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1087		1542
1088	open my $fh2, "$mode&" . fileno $fh	1543	open my $fh2, $mode, $fh
1089	or die "cannot dup() filehandle: $!,";	1544	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1090		1545
1091	# we assume CLOEXEC is already set by perl in all important cases	1546	# we assume CLOEXEC is already set by perl in all important cases
1092		1547
1093	($fh2, $rw)	1548	($fh2, $rw)
1094	}	1549	}
1095		1550
		1551	=head1 SIMPLIFIED AE API
		1552
		1553	Starting with version 5.0, AnyEvent officially supports a second, much
		1554	simpler, API that is designed to reduce the calling, typing and memory
		1555	overhead by using function call syntax and a fixed number of parameters.
		1556
		1557	See the L<AE> manpage for details.
		1558
		1559	=cut
		1560
		1561	package AE;
		1562
		1563	our $VERSION = $AnyEvent::VERSION;
		1564
		1565	sub _reset() {
		1566	eval q{
		1567	# fall back to the main API by default - backends and AnyEvent::Base
		1568	# implementations can overwrite these.
		1569
		1570	sub io($$$) {
		1571	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1572	}
		1573
		1574	sub timer($$$) {
		1575	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1576	}
		1577
		1578	sub signal($$) {
		1579	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1580	}
		1581
		1582	sub child($$) {
		1583	AnyEvent->child (pid => $_[0], cb => $_[1])
		1584	}
		1585
		1586	sub idle($) {
		1587	AnyEvent->idle (cb => $_[0]);
		1588	}
		1589
		1590	sub cv(;&) {
		1591	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1592	}
		1593
		1594	sub now() {
		1595	AnyEvent->now
		1596	}
		1597
		1598	sub now_update() {
		1599	AnyEvent->now_update
		1600	}
		1601
		1602	sub time() {
		1603	AnyEvent->time
		1604	}
		1605
		1606	*postpone = \&AnyEvent::postpone;
		1607	*log = \&AnyEvent::log;
		1608	};
		1609	die if $@;
		1610	}
		1611
		1612	BEGIN { _reset }
		1613
1096	package AnyEvent::Base;	1614	package AnyEvent::Base;
1097		1615
1098	# default implementations for many methods	1616	# default implementations for many methods
1099		1617
1100	BEGIN {	1618	sub time {
		1619	eval q{ # poor man's autoloading {}
		1620	# probe for availability of Time::HiRes
1101	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1621	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1622	*time = sub { Time::HiRes::time () };
1102	*_time = \&Time::HiRes::time;	1623	*AE::time = \& Time::HiRes::time ;
		1624	*now = \&time;
		1625	AnyEvent::log 8 => "using Time::HiRes for sub-second timing accuracy.";
1103	# if (eval "use POSIX (); (POSIX::times())...	1626	# if (eval "use POSIX (); (POSIX::times())...
1104	} else {	1627	} else {
1105	*_time = sub { time }; # epic fail	1628	*time = sub { CORE::time };
		1629	*AE::time = sub (){ CORE::time };
		1630	*now = \&time;
		1631	AnyEvent::log 3 => "Using built-in time(), no sub-second resolution!";
		1632	}
		1633	};
		1634	die if $@;
		1635
		1636	&time
		1637	}
		1638
		1639	*now = \&time;
		1640	sub now_update { }
		1641
		1642	sub _poll {
		1643	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1644	}
		1645
		1646	# default implementation for ->condvar
		1647	# in fact, the default should not be overwritten
		1648
		1649	sub condvar {
		1650	eval q{ # poor man's autoloading {}
		1651	*condvar = sub {
		1652	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1653	};
		1654
		1655	*AE::cv = sub (;&) {
		1656	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1657	};
		1658	};
		1659	die if $@;
		1660
		1661	&condvar
		1662	}
		1663
		1664	# default implementation for ->signal
		1665
		1666	our $HAVE_ASYNC_INTERRUPT;
		1667
		1668	sub _have_async_interrupt() {
		1669	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1670	&& eval "use Async::Interrupt 1.02 (); 1")
		1671	unless defined $HAVE_ASYNC_INTERRUPT;
		1672
		1673	$HAVE_ASYNC_INTERRUPT
		1674	}
		1675
		1676	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1677	our (%SIG_ASY, %SIG_ASY_W);
		1678	our ($SIG_COUNT, $SIG_TW);
		1679
		1680	# install a dummy wakeup watcher to reduce signal catching latency
		1681	# used by Impls
		1682	sub _sig_add() {
		1683	unless ($SIG_COUNT++) {
		1684	# try to align timer on a full-second boundary, if possible
		1685	my $NOW = AE::now;
		1686
		1687	$SIG_TW = AE::timer
		1688	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1689	$MAX_SIGNAL_LATENCY,
		1690	sub { } # just for the PERL_ASYNC_CHECK
		1691	;
1106	}	1692	}
1107	}	1693	}
1108		1694
1109	sub time { _time }	1695	sub _sig_del {
1110	sub now { _time }	1696	undef $SIG_TW
1111	sub now_update { }	1697	unless --$SIG_COUNT;
1112
1113	# default implementation for ->condvar
1114
1115	sub condvar {
1116	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1117	}	1698	}
1118		1699
1119	# default implementation for ->signal	1700	our $_sig_name_init; $_sig_name_init = sub {
		1701	eval q{ # poor man's autoloading {}
		1702	undef $_sig_name_init;
1120		1703
1121	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1704	if (_have_async_interrupt) {
		1705	*sig2num = \&Async::Interrupt::sig2num;
		1706	*sig2name = \&Async::Interrupt::sig2name;
		1707	} else {
		1708	require Config;
1122		1709
1123	sub _signal_exec {	1710	my %signame2num;
1124	sysread $SIGPIPE_R, my $dummy, 4;	1711	@signame2num{ split ' ', $Config::Config{sig_name} }
		1712	= split ' ', $Config::Config{sig_num};
1125		1713
1126	while (%SIG_EV) {	1714	my @signum2name;
1127	for (keys %SIG_EV) {	1715	@signum2name[values %signame2num] = keys %signame2num;
1128	delete $SIG_EV{$_};	1716
1129	$_->() for values %{ $SIG_CB{$_} || {} };	1717	*sig2num = sub($) {
		1718	$_[0] > 0 ? shift : $signame2num{+shift}
		1719	};
		1720	*sig2name = sub ($) {
		1721	$_[0] > 0 ? $signum2name[+shift] : shift
		1722	};
1130	}	1723	}
1131	}	1724	};
1132	}	1725	die if $@;
		1726	};
		1727
		1728	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1729	sub sig2name($) { &$_sig_name_init; &sig2name }
1133		1730
1134	sub signal {	1731	sub signal {
1135	my (undef, %arg) = @_;	1732	eval q{ # poor man's autoloading {}
		1733	# probe for availability of Async::Interrupt
		1734	if (_have_async_interrupt) {
		1735	AnyEvent::log 8 => "Using Async::Interrupt for race-free signal handling.";
1136		1736
1137	unless ($SIGPIPE_R) {	1737	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1138	require Fcntl;	1738	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1139		1739
1140	if (AnyEvent::WIN32) {
1141	require AnyEvent::Util;
1142
1143	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1144	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1145	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1146	} else {	1740	} else {
		1741	AnyEvent::log 8 => "Using emulated perl signal handling with latency timer.";
		1742
		1743	if (AnyEvent::WIN32) {
		1744	require AnyEvent::Util;
		1745
		1746	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1747	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1748	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1749	} else {
1147	pipe $SIGPIPE_R, $SIGPIPE_W;	1750	pipe $SIGPIPE_R, $SIGPIPE_W;
1148	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1751	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1149	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1752	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1150		1753
1151	# not strictly required, as $^F is normally 2, but let's make sure...	1754	# not strictly required, as $^F is normally 2, but let's make sure...
1152	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1755	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1153	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1756	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1757	}
		1758
		1759	$SIGPIPE_R
		1760	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1761
		1762	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1154	}	1763	}
1155		1764
1156	$SIGPIPE_R	1765	*signal = $HAVE_ASYNC_INTERRUPT
1157	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1766	? sub {
		1767	my (undef, %arg) = @_;
1158		1768
1159	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1769	# async::interrupt
1160	}
1161
1162	my $signal = uc $arg{signal}	1770	my $signal = sig2num $arg{signal};
1163	or Carp::croak "required option 'signal' is missing";
1164
1165	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1771	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1772
		1773	$SIG_ASY{$signal} ||= new Async::Interrupt
		1774	cb => sub { undef $SIG_EV{$signal} },
		1775	signal => $signal,
		1776	pipe => [$SIGPIPE_R->filenos],
		1777	pipe_autodrain => 0,
		1778	;
		1779
		1780	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1781	}
		1782	: sub {
		1783	my (undef, %arg) = @_;
		1784
		1785	# pure perl
		1786	my $signal = sig2name $arg{signal};
		1787	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1788
1166	$SIG{$signal} ||= sub {	1789	$SIG{$signal} ||= sub {
1167	local $!;	1790	local $!;
1168	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1791	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1169	undef $SIG_EV{$signal};	1792	undef $SIG_EV{$signal};
		1793	};
		1794
		1795	# can't do signal processing without introducing races in pure perl,
		1796	# so limit the signal latency.
		1797	_sig_add;
		1798
		1799	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1800	}
		1801	;
		1802
		1803	*AnyEvent::Base::signal::DESTROY = sub {
		1804	my ($signal, $cb) = @{$_[0]};
		1805
		1806	_sig_del;
		1807
		1808	delete $SIG_CB{$signal}{$cb};
		1809
		1810	$HAVE_ASYNC_INTERRUPT
		1811	? delete $SIG_ASY{$signal}
		1812	: # delete doesn't work with older perls - they then
		1813	# print weird messages, or just unconditionally exit
		1814	# instead of getting the default action.
		1815	undef $SIG{$signal}
		1816	unless keys %{ $SIG_CB{$signal} };
		1817	};
		1818
		1819	*_signal_exec = sub {
		1820	$HAVE_ASYNC_INTERRUPT
		1821	? $SIGPIPE_R->drain
		1822	: sysread $SIGPIPE_R, (my $dummy), 9;
		1823
		1824	while (%SIG_EV) {
		1825	for (keys %SIG_EV) {
		1826	delete $SIG_EV{$_};
		1827	&$_ for values %{ $SIG_CB{$_} || {} };
		1828	}
		1829	}
		1830	};
1170	};	1831	};
		1832	die if $@;
1171		1833
1172	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"	1834	&signal
1173	}
1174
1175	sub AnyEvent::Base::signal::DESTROY {
1176	my ($signal, $cb) = @{$_[0]};
1177
1178	delete $SIG_CB{$signal}{$cb};
1179
1180	# delete doesn't work with older perls - they then
1181	# print weird messages, or just unconditionally exit
1182	# instead of getting the default action.
1183	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1184	}	1835	}
1185		1836
1186	# default implementation for ->child	1837	# default implementation for ->child
1187		1838
1188	our %PID_CB;	1839	our %PID_CB;
1189	our $CHLD_W;	1840	our $CHLD_W;
1190	our $CHLD_DELAY_W;	1841	our $CHLD_DELAY_W;
1191	our $WNOHANG;
1192		1842
1193	sub _sigchld {	1843	# used by many Impl's
1194	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1844	sub _emit_childstatus($$) {
		1845	my (undef, $rpid, $rstatus) = @_;
		1846
		1847	$_->($rpid, $rstatus)
1195	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1848	for values %{ $PID_CB{$rpid} || {} },
1196	(values %{ $PID_CB{0} || {} });	1849	values %{ $PID_CB{0} || {} };
1197	}
1198	}	1850	}
1199		1851
1200	sub child {	1852	sub child {
		1853	eval q{ # poor man's autoloading {}
		1854	*_sigchld = sub {
		1855	my $pid;
		1856
		1857	AnyEvent->_emit_childstatus ($pid, $?)
		1858	while ($pid = waitpid -1, WNOHANG) > 0;
		1859	};
		1860
		1861	*child = sub {
1201	my (undef, %arg) = @_;	1862	my (undef, %arg) = @_;
1202		1863
1203	defined (my $pid = $arg{pid} + 0)	1864	my $pid = $arg{pid};
1204	or Carp::croak "required option 'pid' is missing";	1865	my $cb = $arg{cb};
1205		1866
1206	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1867	$PID_CB{$pid}{$cb+0} = $cb;
1207		1868
1208	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1209
1210	unless ($CHLD_W) {	1869	unless ($CHLD_W) {
1211	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1870	$CHLD_W = AE::signal CHLD => \&_sigchld;
1212	# child could be a zombie already, so make at least one round	1871	# child could be a zombie already, so make at least one round
1213	&_sigchld;	1872	&_sigchld;
1214	}	1873	}
1215		1874
1216	bless [$pid, $arg{cb}], "AnyEvent::Base::child"	1875	bless [$pid, $cb+0], "AnyEvent::Base::child"
1217	}	1876	};
1218		1877
1219	sub AnyEvent::Base::child::DESTROY {	1878	*AnyEvent::Base::child::DESTROY = sub {
1220	my ($pid, $cb) = @{$_[0]};	1879	my ($pid, $icb) = @{$_[0]};
1221		1880
1222	delete $PID_CB{$pid}{$cb};	1881	delete $PID_CB{$pid}{$icb};
1223	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1882	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1224		1883
1225	undef $CHLD_W unless keys %PID_CB;	1884	undef $CHLD_W unless keys %PID_CB;
		1885	};
		1886	};
		1887	die if $@;
		1888
		1889	&child
1226	}	1890	}
1227		1891
1228	# idle emulation is done by simply using a timer, regardless	1892	# idle emulation is done by simply using a timer, regardless
1229	# of whether the process is idle or not, and not letting	1893	# of whether the process is idle or not, and not letting
1230	# the callback use more than 50% of the time.	1894	# the callback use more than 50% of the time.
1231	sub idle {	1895	sub idle {
		1896	eval q{ # poor man's autoloading {}
		1897	*idle = sub {
1232	my (undef, %arg) = @_;	1898	my (undef, %arg) = @_;
1233		1899
1234	my ($cb, $w, $rcb) = $arg{cb};	1900	my ($cb, $w, $rcb) = $arg{cb};
1235		1901
1236	$rcb = sub {	1902	$rcb = sub {
1237	if ($cb) {	1903	if ($cb) {
1238	$w = _time;	1904	$w = AE::time;
1239	&$cb;	1905	&$cb;
1240	$w = _time - $w;	1906	$w = AE::time - $w;
1241		1907
1242	# never use more then 50% of the time for the idle watcher,	1908	# never use more then 50% of the time for the idle watcher,
1243	# within some limits	1909	# within some limits
1244	$w = 0.0001 if $w < 0.0001;	1910	$w = 0.0001 if $w < 0.0001;
1245	$w = 5 if $w > 5;	1911	$w = 5 if $w > 5;
1246		1912
1247	$w = AnyEvent->timer (after => $w, cb => $rcb);	1913	$w = AE::timer $w, 0, $rcb;
1248	} else {	1914	} else {
1249	# clean up...	1915	# clean up...
1250	undef $w;	1916	undef $w;
1251	undef $rcb;	1917	undef $rcb;
		1918	}
		1919	};
		1920
		1921	$w = AE::timer 0.05, 0, $rcb;
		1922
		1923	bless \\$cb, "AnyEvent::Base::idle"
1252	}	1924	};
		1925
		1926	*AnyEvent::Base::idle::DESTROY = sub {
		1927	undef $${$_[0]};
		1928	};
1253	};	1929	};
		1930	die if $@;
1254		1931
1255	$w = AnyEvent->timer (after => 0.05, cb => $rcb);	1932	&idle
1256
1257	bless \\$cb, "AnyEvent::Base::idle"
1258	}
1259
1260	sub AnyEvent::Base::idle::DESTROY {
1261	undef $${$_[0]};
1262	}	1933	}
1263		1934
1264	package AnyEvent::CondVar;	1935	package AnyEvent::CondVar;
1265		1936
1266	our @ISA = AnyEvent::CondVar::Base::;	1937	our @ISA = AnyEvent::CondVar::Base::;
1267		1938
		1939	# only to be used for subclassing
		1940	sub new {
		1941	my $class = shift;
		1942	bless AnyEvent->condvar (@_), $class
		1943	}
		1944
1268	package AnyEvent::CondVar::Base;	1945	package AnyEvent::CondVar::Base;
1269		1946
1270	use overload	1947	#use overload
1271	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1948	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1272	fallback => 1;	1949	# fallback => 1;
		1950
		1951	# save 300+ kilobytes by dirtily hardcoding overloading
		1952	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1953	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1954	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1955	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1956
		1957	our $WAITING;
1273		1958
1274	sub _send {	1959	sub _send {
1275	# nop	1960	# nop
		1961	}
		1962
		1963	sub _wait {
		1964	AnyEvent->_poll until $_[0]{_ae_sent};
1276	}	1965	}
1277		1966
1278	sub send {	1967	sub send {
1279	my $cv = shift;	1968	my $cv = shift;
1280	$cv->{_ae_sent} = [@_];	1969	$cv->{_ae_sent} = [@_];
…		…
1289		1978
1290	sub ready {	1979	sub ready {
1291	$_[0]{_ae_sent}	1980	$_[0]{_ae_sent}
1292	}	1981	}
1293		1982
1294	sub _wait {
1295	AnyEvent->one_event while !$_[0]{_ae_sent};
1296	}
1297
1298	sub recv {	1983	sub recv {
		1984	unless ($_[0]{_ae_sent}) {
		1985	$WAITING
		1986	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1987
		1988	local $WAITING = 1;
1299	$_[0]->_wait;	1989	$_[0]->_wait;
		1990	}
1300		1991
1301	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1992	$_[0]{_ae_croak}
1302	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1993	and Carp::croak $_[0]{_ae_croak};
		1994
		1995	wantarray
		1996	? @{ $_[0]{_ae_sent} }
		1997	: $_[0]{_ae_sent}[0]
1303	}	1998	}
1304		1999
1305	sub cb {	2000	sub cb {
1306	$_[0]{_ae_cb} = $_[1] if @_ > 1;	2001	my $cv = shift;
		2002
		2003	@_
		2004	and $cv->{_ae_cb} = shift
		2005	and $cv->{_ae_sent}
		2006	and (delete $cv->{_ae_cb})->($cv);
		2007
1307	$_[0]{_ae_cb}	2008	$cv->{_ae_cb}
1308	}	2009	}
1309		2010
1310	sub begin {	2011	sub begin {
1311	++$_[0]{_ae_counter};	2012	++$_[0]{_ae_counter};
1312	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	2013	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1317	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	2018	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1318	}	2019	}
1319		2020
1320	# undocumented/compatibility with pre-3.4	2021	# undocumented/compatibility with pre-3.4
1321	*broadcast = \&send;	2022	*broadcast = \&send;
1322	*wait = \&_wait;	2023	*wait = \&recv;
1323		2024
1324	=head1 ERROR AND EXCEPTION HANDLING	2025	=head1 ERROR AND EXCEPTION HANDLING
1325		2026
1326	In general, AnyEvent does not do any error handling - it relies on the	2027	In general, AnyEvent does not do any error handling - it relies on the
1327	caller to do that if required. The L<AnyEvent::Strict> module (see also	2028	caller to do that if required. The L<AnyEvent::Strict> module (see also
…		…
1339	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and	2040	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
1340	so on.	2041	so on.
1341		2042
1342	=head1 ENVIRONMENT VARIABLES	2043	=head1 ENVIRONMENT VARIABLES
1343		2044
1344	The following environment variables are used by this module or its	2045	AnyEvent supports a number of environment variables that tune the
1345	submodules.	2046	runtime behaviour. They are usually evaluated when AnyEvent is
		2047	loaded, initialised, or a submodule that uses them is loaded. Many of
		2048	them also cause AnyEvent to load additional modules - for example,
		2049	C<PERL_ANYEVENT_DEBUG_WRAP> causes the L<AnyEvent::Debug> module to be
		2050	loaded.
1346		2051
1347	Note that AnyEvent will remove I<all> environment variables starting with	2052	All the environment variables documented here start with
1348	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is	2053	C<PERL_ANYEVENT_>, which is what AnyEvent considers its own
1349	enabled.	2054	namespace. Other modules are encouraged (but by no means required) to use
		2055	C<PERL_ANYEVENT_SUBMODULE> if they have registered the AnyEvent::Submodule
		2056	namespace on CPAN, for any submodule. For example, L<AnyEvent::HTTP> could
		2057	be expected to use C<PERL_ANYEVENT_HTTP_PROXY> (it should not access env
		2058	variables starting with C<AE_>, see below).
		2059
		2060	All variables can also be set via the C<AE_> prefix, that is, instead
		2061	of setting C<PERL_ANYEVENT_VERBOSE> you can also set C<AE_VERBOSE>. In
		2062	case there is a clash btween anyevent and another program that uses
		2063	C<AE_something> you can set the corresponding C<PERL_ANYEVENT_something>
		2064	variable to the empty string, as those variables take precedence.
		2065
		2066	When AnyEvent is first loaded, it copies all C<AE_xxx> env variables
		2067	to their C<PERL_ANYEVENT_xxx> counterpart unless that variable already
		2068	exists. If taint mode is on, then AnyEvent will remove I<all> environment
		2069	variables starting with C<PERL_ANYEVENT_> from C<%ENV> (or replace them
		2070	with C<undef> or the empty string, if the corresaponding C<AE_> variable
		2071	is set).
		2072
		2073	The exact algorithm is currently:
		2074
		2075	1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
		2076	2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
		2077	3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
		2078
		2079	This ensures that child processes will not see the C<AE_> variables.
		2080
		2081	The following environment variables are currently known to AnyEvent:
1350		2082
1351	=over 4	2083	=over 4
1352		2084
1353	=item C<PERL_ANYEVENT_VERBOSE>	2085	=item C<PERL_ANYEVENT_VERBOSE>
1354		2086
1355	By default, AnyEvent will be completely silent except in fatal	2087	By default, AnyEvent will log messages with loglevel C<4> (C<error>) or
1356	conditions. You can set this environment variable to make AnyEvent more	2088	higher (see L<AnyEvent::Log>). You can set this environment variable to a
1357	talkative.	2089	numerical loglevel to make AnyEvent more (or less) talkative.
1358		2090
		2091	If you want to do more than just set the global logging level
		2092	you should have a look at C<PERL_ANYEVENT_LOG>, which allows much more
		2093	complex specifications.
		2094
		2095	When set to C<0> (C<off>), then no messages whatsoever will be logged with
		2096	everything else at defaults.
		2097
1359	When set to C<1> or higher, causes AnyEvent to warn about unexpected	2098	When set to C<5> or higher (C<warn>), AnyEvent warns about unexpected
1360	conditions, such as not being able to load the event model specified by	2099	conditions, such as not being able to load the event model specified by
1361	C<PERL_ANYEVENT_MODEL>.	2100	C<PERL_ANYEVENT_MODEL>, or a guard callback throwing an exception - this
		2101	is the minimum recommended level for use during development.
1362		2102
1363	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	2103	When set to C<7> or higher (info), AnyEvent reports which event model it
1364	model it chooses.	2104	chooses.
		2105
		2106	When set to C<8> or higher (debug), then AnyEvent will report extra
		2107	information on which optional modules it loads and how it implements
		2108	certain features.
		2109
		2110	=item C<PERL_ANYEVENT_LOG>
		2111
		2112	Accepts rather complex logging specifications. For example, you could log
		2113	all C<debug> messages of some module to stderr, warnings and above to
		2114	stderr, and errors and above to syslog, with:
		2115
		2116	PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
		2117
		2118	For the rather extensive details, see L<AnyEvent::Log>.
		2119
		2120	This variable is evaluated when AnyEvent (or L<AnyEvent::Log>) is loaded,
		2121	so will take effect even before AnyEvent has initialised itself.
		2122
		2123	Note that specifying this environment variable causes the L<AnyEvent::Log>
		2124	module to be loaded, while C<PERL_ANYEVENT_VERBOSE> does not, so only
		2125	using the latter saves a few hundred kB of memory unless a module
		2126	explicitly needs the extra features of AnyEvent::Log.
1365		2127
1366	=item C<PERL_ANYEVENT_STRICT>	2128	=item C<PERL_ANYEVENT_STRICT>
1367		2129
1368	AnyEvent does not do much argument checking by default, as thorough	2130	AnyEvent does not do much argument checking by default, as thorough
1369	argument checking is very costly. Setting this variable to a true value	2131	argument checking is very costly. Setting this variable to a true value
1370	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	2132	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1371	check the arguments passed to most method calls. If it finds any problems	2133	check the arguments passed to most method calls. If it finds any problems,
1372	it will croak.	2134	it will croak.
1373		2135
1374	In other words, enables "strict" mode.	2136	In other words, enables "strict" mode.
1375		2137
1376	Unlike C<use strict>, it is definitely recommended ot keep it off in	2138	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1377	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	2139	>>, it is definitely recommended to keep it off in production. Keeping
1378	developing programs can be very useful, however.	2140	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		2141	can be very useful, however.
		2142
		2143	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		2144
		2145	If this env variable is nonempty, then its contents will be interpreted by
		2146	C<AnyEvent::Socket::parse_hostport> and C<AnyEvent::Debug::shell> (after
		2147	replacing every occurance of C<$$> by the process pid). The shell object
		2148	is saved in C<$AnyEvent::Debug::SHELL>.
		2149
		2150	This happens when the first watcher is created.
		2151
		2152	For example, to bind a debug shell on a unix domain socket in
		2153	F<< /tmp/debug<pid>.sock >>, you could use this:
		2154
		2155	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		2156	# connect with e.g.: socat readline /tmp/debug123.sock
		2157
		2158	Or to bind to tcp port 4545 on localhost:
		2159
		2160	PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
		2161	# connect with e.g.: telnet localhost 4545
		2162
		2163	Note that creating sockets in F</tmp> or on localhost is very unsafe on
		2164	multiuser systems.
		2165
		2166	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2167
		2168	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2169	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
1379		2170
1380	=item C<PERL_ANYEVENT_MODEL>	2171	=item C<PERL_ANYEVENT_MODEL>
1381		2172
1382	This can be used to specify the event model to be used by AnyEvent, before	2173	This can be used to specify the event model to be used by AnyEvent, before
1383	auto detection and -probing kicks in. It must be a string consisting	2174	auto detection and -probing kicks in.
1384	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	2175
		2176	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2177	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
1385	and the resulting module name is loaded and if the load was successful,	2178	resulting module name is loaded and - if the load was successful - used as
1386	used as event model. If it fails to load AnyEvent will proceed with	2179	event model backend. If it fails to load then AnyEvent will proceed with
1387	auto detection and -probing.	2180	auto detection and -probing.
1388		2181
1389	This functionality might change in future versions.	2182	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2183	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2184	the end of a string designates a module name and quotes it appropriately).
1390		2185
1391	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	2186	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1392	could start your program like this:	2187	could start your program like this:
1393		2188
1394	PERL_ANYEVENT_MODEL=Perl perl ...	2189	PERL_ANYEVENT_MODEL=Perl perl ...
		2190
		2191	=item C<PERL_ANYEVENT_IO_MODEL>
		2192
		2193	The current file I/O model - see L<AnyEvent::IO> for more info.
		2194
		2195	At the moment, only C<Perl> (small, pure-perl, synchronous) and
		2196	C<IOAIO> (truly asynchronous) are supported. The default is C<IOAIO> if
		2197	L<AnyEvent::AIO> can be loaded, otherwise it is C<Perl>.
1395		2198
1396	=item C<PERL_ANYEVENT_PROTOCOLS>	2199	=item C<PERL_ANYEVENT_PROTOCOLS>
1397		2200
1398	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences	2201	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1399	for IPv4 or IPv6. The default is unspecified (and might change, or be the result	2202	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
…		…
1412	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>	2215	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1413	- only support IPv4, never try to resolve or contact IPv6	2216	- only support IPv4, never try to resolve or contact IPv6
1414	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or	2217	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1415	IPv6, but prefer IPv6 over IPv4.	2218	IPv6, but prefer IPv6 over IPv4.
1416		2219
		2220	=item C<PERL_ANYEVENT_HOSTS>
		2221
		2222	This variable, if specified, overrides the F</etc/hosts> file used by
		2223	L<AnyEvent::Socket>C<::resolve_sockaddr>, i.e. hosts aliases will be read
		2224	from that file instead.
		2225
1417	=item C<PERL_ANYEVENT_EDNS0>	2226	=item C<PERL_ANYEVENT_EDNS0>
1418		2227
1419	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension	2228	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension for
1420	for DNS. This extension is generally useful to reduce DNS traffic, but	2229	DNS. This extension is generally useful to reduce DNS traffic, especially
1421	some (broken) firewalls drop such DNS packets, which is why it is off by	2230	when DNSSEC is involved, but some (broken) firewalls drop such DNS
1422	default.	2231	packets, which is why it is off by default.
1423		2232
1424	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce	2233	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1425	EDNS0 in its DNS requests.	2234	EDNS0 in its DNS requests.
1426		2235
1427	=item C<PERL_ANYEVENT_MAX_FORKS>	2236	=item C<PERL_ANYEVENT_MAX_FORKS>
1428		2237
1429	The maximum number of child processes that C<AnyEvent::Util::fork_call>	2238	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1430	will create in parallel.	2239	will create in parallel.
		2240
		2241	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2242
		2243	The default value for the C<max_outstanding> parameter for the default DNS
		2244	resolver - this is the maximum number of parallel DNS requests that are
		2245	sent to the DNS server.
		2246
		2247	=item C<PERL_ANYEVENT_MAX_SIGNAL_LATENCY>
		2248
		2249	Perl has inherently racy signal handling (you can basically choose between
		2250	losing signals and memory corruption) - pure perl event loops (including
		2251	C<AnyEvent::Loop>, when C<Async::Interrupt> isn't available) therefore
		2252	have to poll regularly to avoid losing signals.
		2253
		2254	Some event loops are racy, but don't poll regularly, and some event loops
		2255	are written in C but are still racy. For those event loops, AnyEvent
		2256	installs a timer that regularly wakes up the event loop.
		2257
		2258	By default, the interval for this timer is C<10> seconds, but you can
		2259	override this delay with this environment variable (or by setting
		2260	the C<$AnyEvent::MAX_SIGNAL_LATENCY> variable before creating signal
		2261	watchers).
		2262
		2263	Lower values increase CPU (and energy) usage, higher values can introduce
		2264	long delays when reaping children or waiting for signals.
		2265
		2266	The L<AnyEvent::Async> module, if available, will be used to avoid this
		2267	polling (with most event loops).
		2268
		2269	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2270
		2271	The absolute path to a F<resolv.conf>-style file to use instead of
		2272	F</etc/resolv.conf> (or the OS-specific configuration) in the default
		2273	resolver, or the empty string to select the default configuration.
		2274
		2275	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2276
		2277	When neither C<ca_file> nor C<ca_path> was specified during
		2278	L<AnyEvent::TLS> context creation, and either of these environment
		2279	variables are nonempty, they will be used to specify CA certificate
		2280	locations instead of a system-dependent default.
		2281
		2282	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2283
		2284	When these are set to C<1>, then the respective modules are not
		2285	loaded. Mostly good for testing AnyEvent itself.
1431		2286
1432	=back	2287	=back
1433		2288
1434	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2289	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1435		2290
…		…
1493	warn "read: $input\n"; # output what has been read	2348	warn "read: $input\n"; # output what has been read
1494	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2349	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1495	},	2350	},
1496	);	2351	);
1497		2352
1498	my $time_watcher; # can only be used once
1499
1500	sub new_timer {
1501	$timer = AnyEvent->timer (after => 1, cb => sub {	2353	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1502	warn "timeout\n"; # print 'timeout' about every second	2354	warn "timeout\n"; # print 'timeout' at most every second
1503	&new_timer; # and restart the time
1504	});	2355	});
1505	}
1506
1507	new_timer; # create first timer
1508		2356
1509	$cv->recv; # wait until user enters /^q/i	2357	$cv->recv; # wait until user enters /^q/i
1510		2358
1511	=head1 REAL-WORLD EXAMPLE	2359	=head1 REAL-WORLD EXAMPLE
1512		2360
…		…
1585		2433
1586	The actual code goes further and collects all errors (C<die>s, exceptions)	2434	The actual code goes further and collects all errors (C<die>s, exceptions)
1587	that occurred during request processing. The C<result> method detects	2435	that occurred during request processing. The C<result> method detects
1588	whether an exception as thrown (it is stored inside the $txn object)	2436	whether an exception as thrown (it is stored inside the $txn object)
1589	and just throws the exception, which means connection errors and other	2437	and just throws the exception, which means connection errors and other
1590	problems get reported tot he code that tries to use the result, not in a	2438	problems get reported to the code that tries to use the result, not in a
1591	random callback.	2439	random callback.
1592		2440
1593	All of this enables the following usage styles:	2441	All of this enables the following usage styles:
1594		2442
1595	1. Blocking:	2443	1. Blocking:
…		…
1643	through AnyEvent. The benchmark creates a lot of timers (with a zero	2491	through AnyEvent. The benchmark creates a lot of timers (with a zero
1644	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2492	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1645	which it is), lets them fire exactly once and destroys them again.	2493	which it is), lets them fire exactly once and destroys them again.
1646		2494
1647	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2495	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1648	distribution.	2496	distribution. It uses the L<AE> interface, which makes a real difference
		2497	for the EV and Perl backends only.
1649		2498
1650	=head3 Explanation of the columns	2499	=head3 Explanation of the columns
1651		2500
1652	I<watcher> is the number of event watchers created/destroyed. Since	2501	I<watcher> is the number of event watchers created/destroyed. Since
1653	different event models feature vastly different performances, each event	2502	different event models feature vastly different performances, each event
…		…
1674	watcher.	2523	watcher.
1675		2524
1676	=head3 Results	2525	=head3 Results
1677		2526
1678	name watchers bytes create invoke destroy comment	2527	name watchers bytes create invoke destroy comment
1679	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2528	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1680	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2529	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1681	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2530	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1682	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2531	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1683	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2532	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1684	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2533	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2534	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2535	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1685	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2536	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1686	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2537	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1687	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2538	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1688	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2539	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1689		2540
1690	=head3 Discussion	2541	=head3 Discussion
1691		2542
1692	The benchmark does I<not> measure scalability of the event loop very	2543	The benchmark does I<not> measure scalability of the event loop very
1693	well. For example, a select-based event loop (such as the pure perl one)	2544	well. For example, a select-based event loop (such as the pure perl one)
…		…
1705	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2556	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1706	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2557	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1707	cycles with POE.	2558	cycles with POE.
1708		2559
1709	C<EV> is the sole leader regarding speed and memory use, which are both	2560	C<EV> is the sole leader regarding speed and memory use, which are both
1710	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2561	maximal/minimal, respectively. When using the L<AE> API there is zero
		2562	overhead (when going through the AnyEvent API create is about 5-6 times
		2563	slower, with other times being equal, so still uses far less memory than
1711	far less memory than any other event loop and is still faster than Event	2564	any other event loop and is still faster than Event natively).
1712	natively.
1713		2565
1714	The pure perl implementation is hit in a few sweet spots (both the	2566	The pure perl implementation is hit in a few sweet spots (both the
1715	constant timeout and the use of a single fd hit optimisations in the perl	2567	constant timeout and the use of a single fd hit optimisations in the perl
1716	interpreter and the backend itself). Nevertheless this shows that it	2568	interpreter and the backend itself). Nevertheless this shows that it
1717	adds very little overhead in itself. Like any select-based backend its	2569	adds very little overhead in itself. Like any select-based backend its
1718	performance becomes really bad with lots of file descriptors (and few of	2570	performance becomes really bad with lots of file descriptors (and few of
1719	them active), of course, but this was not subject of this benchmark.	2571	them active), of course, but this was not subject of this benchmark.
1720		2572
1721	The C<Event> module has a relatively high setup and callback invocation	2573	The C<Event> module has a relatively high setup and callback invocation
1722	cost, but overall scores in on the third place.	2574	cost, but overall scores in on the third place.
		2575
		2576	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2577	when using its pure perl backend.
1723		2578
1724	C<Glib>'s memory usage is quite a bit higher, but it features a	2579	C<Glib>'s memory usage is quite a bit higher, but it features a
1725	faster callback invocation and overall ends up in the same class as	2580	faster callback invocation and overall ends up in the same class as
1726	C<Event>. However, Glib scales extremely badly, doubling the number of	2581	C<Event>. However, Glib scales extremely badly, doubling the number of
1727	watchers increases the processing time by more than a factor of four,	2582	watchers increases the processing time by more than a factor of four,
…		…
1762	(even when used without AnyEvent), but most event loops have acceptable	2617	(even when used without AnyEvent), but most event loops have acceptable
1763	performance with or without AnyEvent.	2618	performance with or without AnyEvent.
1764		2619
1765	=item * The overhead AnyEvent adds is usually much smaller than the overhead of	2620	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
1766	the actual event loop, only with extremely fast event loops such as EV	2621	the actual event loop, only with extremely fast event loops such as EV
1767	adds AnyEvent significant overhead.	2622	does AnyEvent add significant overhead.
1768		2623
1769	=item * You should avoid POE like the plague if you want performance or	2624	=item * You should avoid POE like the plague if you want performance or
1770	reasonable memory usage.	2625	reasonable memory usage.
1771		2626
1772	=back	2627	=back
…		…
1788	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2643	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1789	(1%) are active. This mirrors the activity of large servers with many	2644	(1%) are active. This mirrors the activity of large servers with many
1790	connections, most of which are idle at any one point in time.	2645	connections, most of which are idle at any one point in time.
1791		2646
1792	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2647	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1793	distribution.	2648	distribution. It uses the L<AE> interface, which makes a real difference
		2649	for the EV and Perl backends only.
1794		2650
1795	=head3 Explanation of the columns	2651	=head3 Explanation of the columns
1796		2652
1797	I<sockets> is the number of sockets, and twice the number of "servers" (as	2653	I<sockets> is the number of sockets, and twice the number of "servers" (as
1798	each server has a read and write socket end).	2654	each server has a read and write socket end).
…		…
1805	it to another server. This includes deleting the old timeout and creating	2661	it to another server. This includes deleting the old timeout and creating
1806	a new one that moves the timeout into the future.	2662	a new one that moves the timeout into the future.
1807		2663
1808	=head3 Results	2664	=head3 Results
1809		2665
1810	name sockets create request	2666	name sockets create request
1811	EV 20000 69.01 11.16	2667	EV 20000 62.66 7.99
1812	Perl 20000 73.32 35.87	2668	Perl 20000 68.32 32.64
1813	Event 20000 212.62 257.32	2669	IOAsync 20000 174.06 101.15 epoll
1814	Glib 20000 651.16 1896.30	2670	IOAsync 20000 174.67 610.84 poll
		2671	Event 20000 202.69 242.91
		2672	Glib 20000 557.01 1689.52
1815	POE 20000 349.67 12317.24 uses POE::Loop::Event	2673	POE 20000 341.54 12086.32 uses POE::Loop::Event
1816		2674
1817	=head3 Discussion	2675	=head3 Discussion
1818		2676
1819	This benchmark I<does> measure scalability and overall performance of the	2677	This benchmark I<does> measure scalability and overall performance of the
1820	particular event loop.	2678	particular event loop.
…		…
1822	EV is again fastest. Since it is using epoll on my system, the setup time	2680	EV is again fastest. Since it is using epoll on my system, the setup time
1823	is relatively high, though.	2681	is relatively high, though.
1824		2682
1825	Perl surprisingly comes second. It is much faster than the C-based event	2683	Perl surprisingly comes second. It is much faster than the C-based event
1826	loops Event and Glib.	2684	loops Event and Glib.
		2685
		2686	IO::Async performs very well when using its epoll backend, and still quite
		2687	good compared to Glib when using its pure perl backend.
1827		2688
1828	Event suffers from high setup time as well (look at its code and you will	2689	Event suffers from high setup time as well (look at its code and you will
1829	understand why). Callback invocation also has a high overhead compared to	2690	understand why). Callback invocation also has a high overhead compared to
1830	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2691	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1831	uses select or poll in basically all documented configurations.	2692	uses select or poll in basically all documented configurations.
…		…
1900		2761
1901	Recently I was told about the benchmark in the IO::Lambda manpage, which	2762	Recently I was told about the benchmark in the IO::Lambda manpage, which
1902	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark	2763	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
1903	simply compares IO::Lambda with POE, and IO::Lambda looks better (which	2764	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
1904	shouldn't come as a surprise to anybody). As such, the benchmark is	2765	shouldn't come as a surprise to anybody). As such, the benchmark is
1905	fine, and shows that the AnyEvent backend from IO::Lambda isn't very	2766	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
1906	optimal. But how would AnyEvent compare when used without the extra	2767	very optimal. But how would AnyEvent compare when used without the extra
1907	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.	2768	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
1908		2769
1909	The benchmark itself creates an echo-server, and then, for 500 times,	2770	The benchmark itself creates an echo-server, and then, for 500 times,
1910	connects to the echo server, sends a line, waits for the reply, and then	2771	connects to the echo server, sends a line, waits for the reply, and then
1911	creates the next connection. This is a rather bad benchmark, as it doesn't	2772	creates the next connection. This is a rather bad benchmark, as it doesn't
1912	test the efficiency of the framework, but it is a benchmark nevertheless.	2773	test the efficiency of the framework or much non-blocking I/O, but it is a
		2774	benchmark nevertheless.
1913		2775
1914	name runtime	2776	name runtime
1915	Lambda/select 0.330 sec	2777	Lambda/select 0.330 sec
1916	+ optimized 0.122 sec	2778	+ optimized 0.122 sec
1917	Lambda/AnyEvent 0.327 sec	2779	Lambda/AnyEvent 0.327 sec
…		…
1923		2785
1924	AnyEvent/select/nb 0.085 sec	2786	AnyEvent/select/nb 0.085 sec
1925	AnyEvent/EV/nb 0.068 sec	2787	AnyEvent/EV/nb 0.068 sec
1926	+state machine 0.134 sec	2788	+state machine 0.134 sec
1927		2789
1928	The benchmark is also a bit unfair (my fault) - the IO::Lambda	2790	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
1929	benchmarks actually make blocking connects and use 100% blocking I/O,	2791	benchmarks actually make blocking connects and use 100% blocking I/O,
1930	defeating the purpose of an event-based solution. All of the newly	2792	defeating the purpose of an event-based solution. All of the newly
1931	written AnyEvent benchmarks use 100% non-blocking connects (using	2793	written AnyEvent benchmarks use 100% non-blocking connects (using
1932	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS	2794	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
1933	resolver), so AnyEvent is at a disadvantage here as non-blocking connects	2795	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
1934	generally require a lot more bookkeeping and event handling than blocking	2796	generally require a lot more bookkeeping and event handling than blocking
1935	connects (which involve a single syscall only).	2797	connects (which involve a single syscall only).
1936		2798
1937	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which	2799	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
1938	offers similar expressive power as POE and IO::Lambda (using conventional	2800	offers similar expressive power as POE and IO::Lambda, using conventional
1939	Perl syntax), which means both the echo server and the client are 100%	2801	Perl syntax. This means that both the echo server and the client are 100%
1940	non-blocking w.r.t. I/O, further placing it at a disadvantage.	2802	non-blocking, further placing it at a disadvantage.
1941		2803
1942	As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets	2804	As you can see, the AnyEvent + EV combination even beats the
1943	benchmark", while AnyEvent + its pure perl backend easily beats	2805	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1944	IO::Lambda and POE.	2806	backend easily beats IO::Lambda and POE.
1945		2807
1946	And even the 100% non-blocking version written using the high-level (and	2808	And even the 100% non-blocking version written using the high-level (and
1947	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda,	2809	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2810	higher level ("unoptimised") abstractions by a large margin, even though
1948	even thought it does all of DNS, tcp-connect and socket I/O in a	2811	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
1949	non-blocking way.	2812
		2813	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2814	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2815	part of the IO::Lambda distribution and were used without any changes.
1950		2816
1951		2817
1952	=head1 SIGNALS	2818	=head1 SIGNALS
1953		2819
1954	AnyEvent currently installs handlers for these signals:	2820	AnyEvent currently installs handlers for these signals:
…		…
1958	=item SIGCHLD	2824	=item SIGCHLD
1959		2825
1960	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2826	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1961	emulation for event loops that do not support them natively. Also, some	2827	emulation for event loops that do not support them natively. Also, some
1962	event loops install a similar handler.	2828	event loops install a similar handler.
		2829
		2830	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2831	AnyEvent will reset it to default, to avoid losing child exit statuses.
1963		2832
1964	=item SIGPIPE	2833	=item SIGPIPE
1965		2834
1966	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2835	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1967	when AnyEvent gets loaded.	2836	when AnyEvent gets loaded.
…		…
1979		2848
1980	=back	2849	=back
1981		2850
1982	=cut	2851	=cut
1983		2852
		2853	undef $SIG{CHLD}
		2854	if $SIG{CHLD} eq 'IGNORE';
		2855
1984	$SIG{PIPE} = sub { }	2856	$SIG{PIPE} = sub { }
1985	unless defined $SIG{PIPE};	2857	unless defined $SIG{PIPE};
1986		2858
		2859	=head1 RECOMMENDED/OPTIONAL MODULES
		2860
		2861	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2862	its built-in modules) are required to use it.
		2863
		2864	That does not mean that AnyEvent won't take advantage of some additional
		2865	modules if they are installed.
		2866
		2867	This section explains which additional modules will be used, and how they
		2868	affect AnyEvent's operation.
		2869
		2870	=over 4
		2871
		2872	=item L<Async::Interrupt>
		2873
		2874	This slightly arcane module is used to implement fast signal handling: To
		2875	my knowledge, there is no way to do completely race-free and quick
		2876	signal handling in pure perl. To ensure that signals still get
		2877	delivered, AnyEvent will start an interval timer to wake up perl (and
		2878	catch the signals) with some delay (default is 10 seconds, look for
		2879	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2880
		2881	If this module is available, then it will be used to implement signal
		2882	catching, which means that signals will not be delayed, and the event loop
		2883	will not be interrupted regularly, which is more efficient (and good for
		2884	battery life on laptops).
		2885
		2886	This affects not just the pure-perl event loop, but also other event loops
		2887	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2888
		2889	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2890	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2891	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2892	does nothing for those backends.
		2893
		2894	=item L<EV>
		2895
		2896	This module isn't really "optional", as it is simply one of the backend
		2897	event loops that AnyEvent can use. However, it is simply the best event
		2898	loop available in terms of features, speed and stability: It supports
		2899	the AnyEvent API optimally, implements all the watcher types in XS, does
		2900	automatic timer adjustments even when no monotonic clock is available,
		2901	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2902	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2903	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2904
		2905	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2906	then this module will do nothing for you.
		2907
		2908	=item L<Guard>
		2909
		2910	The guard module, when used, will be used to implement
		2911	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2912	lot less memory), but otherwise doesn't affect guard operation much. It is
		2913	purely used for performance.
		2914
		2915	=item L<JSON> and L<JSON::XS>
		2916
		2917	One of these modules is required when you want to read or write JSON data
		2918	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2919	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2920
		2921	=item L<Net::SSLeay>
		2922
		2923	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2924	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2925	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2926
		2927	=item L<Time::HiRes>
		2928
		2929	This module is part of perl since release 5.008. It will be used when the
		2930	chosen event library does not come with a timing source of its own. The
		2931	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2932	try to use a monotonic clock for timing stability.
		2933
		2934	=item L<AnyEvent::AIO> (and L<IO::AIO>)
		2935
		2936	The default implementation of L<AnyEvent::IO> is to do I/O synchronously,
		2937	stopping programs while they access the disk, which is fine for a lot of
		2938	programs.
		2939
		2940	Installing AnyEvent::AIO (and its IO::AIO dependency) makes it switch to
		2941	a true asynchronous implementation, so event processing can continue even
		2942	while waiting for disk I/O.
		2943
		2944	=back
		2945
1987		2946
1988	=head1 FORK	2947	=head1 FORK
1989		2948
1990	Most event libraries are not fork-safe. The ones who are usually are	2949	Most event libraries are not fork-safe. The ones who are usually are
1991	because they rely on inefficient but fork-safe C<select> or C<poll>	2950	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1992	calls. Only L<EV> is fully fork-aware.	2951	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2952	are usually badly thought-out hacks that are incompatible with fork in
		2953	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2954	continue event-processing in both parent and child (or both, if you know
		2955	what you are doing).
		2956
		2957	This means that, in general, you cannot fork and do event processing in
		2958	the child if the event library was initialised before the fork (which
		2959	usually happens when the first AnyEvent watcher is created, or the library
		2960	is loaded).
1993		2961
1994	If you have to fork, you must either do so I<before> creating your first	2962	If you have to fork, you must either do so I<before> creating your first
1995	watcher OR you must not use AnyEvent at all in the child.	2963	watcher OR you must not use AnyEvent at all in the child OR you must do
		2964	something completely out of the scope of AnyEvent.
		2965
		2966	The problem of doing event processing in the parent I<and> the child
		2967	is much more complicated: even for backends that I<are> fork-aware or
		2968	fork-safe, their behaviour is not usually what you want: fork clones all
		2969	watchers, that means all timers, I/O watchers etc. are active in both
		2970	parent and child, which is almost never what you want. USing C<exec>
		2971	to start worker children from some kind of manage rprocess is usually
		2972	preferred, because it is much easier and cleaner, at the expense of having
		2973	to have another binary.
1996		2974
1997		2975
1998	=head1 SECURITY CONSIDERATIONS	2976	=head1 SECURITY CONSIDERATIONS
1999		2977
2000	AnyEvent can be forced to load any event model via	2978	AnyEvent can be forced to load any event model via
…		…
2014	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2992	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
2015	be used to probe what backend is used and gain other information (which is	2993	be used to probe what backend is used and gain other information (which is
2016	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2994	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
2017	$ENV{PERL_ANYEVENT_STRICT}.	2995	$ENV{PERL_ANYEVENT_STRICT}.
2018		2996
		2997	Note that AnyEvent will remove I<all> environment variables starting with
		2998	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2999	enabled.
		3000
2019		3001
2020	=head1 BUGS	3002	=head1 BUGS
2021		3003
2022	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	3004	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
2023	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	3005	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
…		…
2026	pronounced).	3008	pronounced).
2027		3009
2028		3010
2029	=head1 SEE ALSO	3011	=head1 SEE ALSO
2030		3012
2031	Utility functions: L<AnyEvent::Util>.	3013	Tutorial/Introduction: L<AnyEvent::Intro>.
2032		3014
2033	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	3015	FAQ: L<AnyEvent::FAQ>.
2034	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	3016
		3017	Utility functions: L<AnyEvent::Util> (misc. grab-bag), L<AnyEvent::Log>
		3018	(simply logging).
		3019
		3020	Development/Debugging: L<AnyEvent::Strict> (stricter checking),
		3021	L<AnyEvent::Debug> (interactive shell, watcher tracing).
		3022
		3023	Supported event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>,
		3024	L<Glib::EV>, L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>,
		3025	L<Qt>, L<POE>, L<FLTK>.
2035		3026
2036	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	3027	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2037	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	3028	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2038	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	3029	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
		3030	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>,
2039	L<AnyEvent::Impl::POE>.	3031	L<AnyEvent::Impl::FLTK>.
2040		3032
2041	Non-blocking file handles, sockets, TCP clients and	3033	Non-blocking handles, pipes, stream sockets, TCP clients and
2042	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	3034	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
		3035
		3036	Asynchronous File I/O: L<AnyEvent::IO>.
2043		3037
2044	Asynchronous DNS: L<AnyEvent::DNS>.	3038	Asynchronous DNS: L<AnyEvent::DNS>.
2045		3039
2046	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	3040	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
2047		3041
2048	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	3042	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		3043	L<AnyEvent::HTTP>.
2049		3044
2050		3045
2051	=head1 AUTHOR	3046	=head1 AUTHOR
2052		3047
2053	Marc Lehmann <schmorp@schmorp.de>	3048	Marc Lehmann <schmorp@schmorp.de>
2054	http://home.schmorp.de/	3049	http://anyevent.schmorp.de
2055		3050
2056	=cut	3051	=cut
2057		3052
2058	1	3053	1
2059		3054

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