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Revision 1.421 by root, Fri Sep 5 22:24:12 2014 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported	5	EV, Event, Glib, Tk, UV, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async,
6	event loops.	6	Qt, 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	});
…		…
172	Note that C<my $w; $w => combination. This is necessary because in Perl,	184	Note that C<my $w; $w => combination. This is necessary because in Perl,
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
		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
177		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> (or a naked file descriptor) to watch	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
…		…
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 {
…		…
245		271
246	Example 2: fire an event after 0.5 seconds, then roughly every second.	272	Example 2: fire an event after 0.5 seconds, then roughly every second.
247		273
248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {	274	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
249	warn "timeout\n";	275	warn "timeout\n";
250	};	276	});
251		277
252	=head3 TIMING ISSUES	278	=head3 TIMING ISSUES
253		279
254	There are two ways to handle timers: based on real time (relative, "fire	280	There are two ways to handle timers: based on real time (relative, "fire
255	in 10 seconds") and based on wallclock time (absolute, "fire at 12	281	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
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	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
351		386
352	You can watch for signals using a signal watcher, C<signal> is the signal	387	You can watch for signals using a signal watcher, C<signal> is the signal
353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl	388	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
354	callback to be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
355		390
…		…
368		403
369	This watcher might use C<%SIG> (depending on the event loop used),	404	This watcher might use C<%SIG> (depending on the event loop used),
370	so programs overwriting those signals directly will likely not work	405	so programs overwriting those signals directly will likely not work
371	correctly.	406	correctly.
372		407
373	Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not
374	support attaching callbacks to signals, which is a pity, as you cannot do
375	race-free signal handling in perl. AnyEvent will try to do it's best, but
376	in some cases, signals will be delayed. The maximum time a signal might
377	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
378	seconds). This variable can be changed only before the first signal
379	watcher is created, and should be left alone otherwise. Higher values
380	will cause fewer spurious wake-ups, which is better for power and CPU
381	saving. All these problems can be avoided by installing the optional
382	L<Async::Interrupt> module.
383
384	Example: exit on SIGINT	408	Example: exit on SIGINT
385		409
386	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
387		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling)
		421	or "unsafe" (asynchronous) - the former might delay signal delivery
		422	indefinitely, the latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support
		432	attaching callbacks to signals in a generic way, which is a pity,
		433	as you cannot do race-free signal handling in perl, requiring
		434	C libraries for this. AnyEvent will try to do its best, which
		435	means in some cases, signals will be delayed. The maximum time
		436	a signal might be delayed is 10 seconds by default, but can
		437	be overriden via C<$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
388	=head2 CHILD PROCESS WATCHERS	447	=head2 CHILD PROCESS WATCHERS
389		448
		449	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		450
390	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.
391		452
392	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,
393	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
394	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
395	any trace events (stopped/continued).	456	finished and an exit status is available, not on any trace events
		457	(stopped/continued).
396		458
397	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
398	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
399	callback arguments.	461	callback arguments.
400		462
…		…
418	thing in an AnyEvent program, you I<have> to create at least one	480	thing in an AnyEvent program, you I<have> to create at least one
419	watcher before you C<fork> the child (alternatively, you can call	481	watcher before you C<fork> the child (alternatively, you can call
420	C<AnyEvent::detect>).	482	C<AnyEvent::detect>).
421		483
422	As most event loops do not support waiting for child events, they will be	484	As most event loops do not support waiting for child events, they will be
423	emulated by AnyEvent in most cases, in which the latency and race problems	485	emulated by AnyEvent in most cases, in which case the latency and race
424	mentioned in the description of signal watchers apply.	486	problems mentioned in the description of signal watchers apply.
425		487
426	Example: fork a process and wait for it	488	Example: fork a process and wait for it
427		489
428	my $done = AnyEvent->condvar;	490	my $done = AnyEvent->condvar;
429		491
		492	# this forks and immediately calls exit in the child. this
		493	# normally has all sorts of bad consequences for your parent,
		494	# so take this as an example only. always fork and exec,
		495	# or call POSIX::_exit, in real code.
430	my $pid = fork or exit 5;	496	my $pid = fork or exit 5;
431		497
432	my $w = AnyEvent->child (	498	my $w = AnyEvent->child (
433	pid => $pid,	499	pid => $pid,
434	cb => sub {	500	cb => sub {
…		…
441	# do something else, then wait for process exit	507	# do something else, then wait for process exit
442	$done->recv;	508	$done->recv;
443		509
444	=head2 IDLE WATCHERS	510	=head2 IDLE WATCHERS
445		511
446	Sometimes there is a need to do something, but it is not so important	512	$w = AnyEvent->idle (cb => <callback>);
447	to do it instantly, but only when there is nothing better to do. This
448	"nothing better to do" is usually defined to be "no other events need
449	attention by the event loop".
450		513
451	Idle watchers ideally get invoked when the event loop has nothing	514	This will repeatedly invoke the callback after the process becomes idle,
452	better to do, just before it would block the process to wait for new	515	until either the watcher is destroyed or new events have been detected.
453	events. Instead of blocking, the idle watcher is invoked.
454		516
455	Most event loops unfortunately do not really support idle watchers (only	517	Idle watchers are useful when there is a need to do something, but it
		518	is not so important (or wise) to do it instantly. The callback will be
		519	invoked only when there is "nothing better to do", which is usually
		520	defined as "all outstanding events have been handled and no new events
		521	have been detected". That means that idle watchers ideally get invoked
		522	when the event loop has just polled for new events but none have been
		523	detected. Instead of blocking to wait for more events, the idle watchers
		524	will be invoked.
		525
		526	Unfortunately, most event loops do not really support idle watchers (only
456	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent	527	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
457	will simply call the callback "from time to time".	528	will simply call the callback "from time to time".
458		529
459	Example: read lines from STDIN, but only process them when the	530	Example: read lines from STDIN, but only process them when the
460	program is otherwise idle:	531	program is otherwise idle:
…		…
476	});	547	});
477	});	548	});
478		549
479	=head2 CONDITION VARIABLES	550	=head2 CONDITION VARIABLES
480		551
		552	$cv = AnyEvent->condvar;
		553
		554	$cv->send (<list>);
		555	my @res = $cv->recv;
		556
481	If you are familiar with some event loops you will know that all of them	557	If you are familiar with some event loops you will know that all of them
482	require you to run some blocking "loop", "run" or similar function that	558	require you to run some blocking "loop", "run" or similar function that
483	will actively watch for new events and call your callbacks.	559	will actively watch for new events and call your callbacks.
484		560
485	AnyEvent is slightly different: it expects somebody else to run the event	561	AnyEvent is slightly different: it expects somebody else to run the event
486	loop and will only block when necessary (usually when told by the user).	562	loop and will only block when necessary (usually when told by the user).
487		563
488	The instrument to do that is called a "condition variable", so called	564	The tool to do that is called a "condition variable", so called because
489	because they represent a condition that must become true.	565	they represent a condition that must become true.
490		566
491	Now is probably a good time to look at the examples further below.	567	Now is probably a good time to look at the examples further below.
492		568
493	Condition variables can be created by calling the C<< AnyEvent->condvar	569	Condition variables can be created by calling the C<< AnyEvent->condvar
494	>> method, usually without arguments. The only argument pair allowed is	570	>> method, usually without arguments. The only argument pair allowed is
…		…
499	After creation, the condition variable is "false" until it becomes "true"	575	After creation, the condition variable is "false" until it becomes "true"
500	by calling the C<send> method (or calling the condition variable as if it	576	by calling the C<send> method (or calling the condition variable as if it
501	were a callback, read about the caveats in the description for the C<<	577	were a callback, read about the caveats in the description for the C<<
502	->send >> method).	578	->send >> method).
503		579
504	Condition variables are similar to callbacks, except that you can	580	Since condition variables are the most complex part of the AnyEvent API, here are
505	optionally wait for them. They can also be called merge points - points	581	some different mental models of what they are - pick the ones you can connect to:
506	in time where multiple outstanding events have been processed. And yet	582
507	another way to call them is transactions - each condition variable can be	583	=over 4
508	used to represent a transaction, which finishes at some point and delivers	584
509	a result.	585	=item * Condition variables are like callbacks - you can call them (and pass them instead
		586	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		587
		588	=item * Condition variables are signals - one side can emit or send them,
		589	the other side can wait for them, or install a handler that is called when
		590	the signal fires.
		591
		592	=item * Condition variables are like "Merge Points" - points in your program
		593	where you merge multiple independent results/control flows into one.
		594
		595	=item * Condition variables represent a transaction - functions that start
		596	some kind of transaction can return them, leaving the caller the choice
		597	between waiting in a blocking fashion, or setting a callback.
		598
		599	=item * Condition variables represent future values, or promises to deliver
		600	some result, long before the result is available.
		601
		602	=back
510		603
511	Condition variables are very useful to signal that something has finished,	604	Condition variables are very useful to signal that something has finished,
512	for example, if you write a module that does asynchronous http requests,	605	for example, if you write a module that does asynchronous http requests,
513	then a condition variable would be the ideal candidate to signal the	606	then a condition variable would be the ideal candidate to signal the
514	availability of results. The user can either act when the callback is	607	availability of results. The user can either act when the callback is
…		…
527		620
528	Condition variables are represented by hash refs in perl, and the keys	621	Condition variables are represented by hash refs in perl, and the keys
529	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	622	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
530	easy (it is often useful to build your own transaction class on top of	623	easy (it is often useful to build your own transaction class on top of
531	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	624	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
532	it's C<new> method in your own C<new> method.	625	its C<new> method in your own C<new> method.
533		626
534	There are two "sides" to a condition variable - the "producer side" which	627	There are two "sides" to a condition variable - the "producer side" which
535	eventually calls C<< -> send >>, and the "consumer side", which waits	628	eventually calls C<< -> send >>, and the "consumer side", which waits
536	for the send to occur.	629	for the send to occur.
537		630
538	Example: wait for a timer.	631	Example: wait for a timer.
539		632
540	# wait till the result is ready	633	# condition: "wait till the timer is fired"
541	my $result_ready = AnyEvent->condvar;	634	my $timer_fired = AnyEvent->condvar;
542		635
543	# do something such as adding a timer	636	# create the timer - we could wait for, say
544	# or socket watcher the calls $result_ready->send	637	# a handle becomign ready, or even an
545	# when the "result" is ready.	638	# AnyEvent::HTTP request to finish, but
546	# in this case, we simply use a timer:	639	# in this case, we simply use a timer:
547	my $w = AnyEvent->timer (	640	my $w = AnyEvent->timer (
548	after => 1,	641	after => 1,
549	cb => sub { $result_ready->send },	642	cb => sub { $timer_fired->send },
550	);	643	);
551		644
552	# this "blocks" (while handling events) till the callback	645	# this "blocks" (while handling events) till the callback
553	# calls -<send	646	# calls ->send
554	$result_ready->recv;	647	$timer_fired->recv;
555		648
556	Example: wait for a timer, but take advantage of the fact that condition	649	Example: wait for a timer, but take advantage of the fact that condition
557	variables are also callable directly.	650	variables are also callable directly.
558		651
559	my $done = AnyEvent->condvar;	652	my $done = AnyEvent->condvar;
…		…
602	they were a code reference). Calling them directly is the same as calling	695	they were a code reference). Calling them directly is the same as calling
603	C<send>.	696	C<send>.
604		697
605	=item $cv->croak ($error)	698	=item $cv->croak ($error)
606		699
607	Similar to send, but causes all call's to C<< ->recv >> to invoke	700	Similar to send, but causes all calls to C<< ->recv >> to invoke
608	C<Carp::croak> with the given error message/object/scalar.	701	C<Carp::croak> with the given error message/object/scalar.
609		702
610	This can be used to signal any errors to the condition variable	703	This can be used to signal any errors to the condition variable
611	user/consumer. Doing it this way instead of calling C<croak> directly	704	user/consumer. Doing it this way instead of calling C<croak> directly
612	delays the error detetcion, but has the overwhelmign advantage that it	705	delays the error detection, but has the overwhelming advantage that it
613	diagnoses the error at the place where the result is expected, and not	706	diagnoses the error at the place where the result is expected, and not
614	deep in some event clalback without connection to the actual code causing	707	deep in some event callback with no connection to the actual code causing
615	the problem.	708	the problem.
616		709
617	=item $cv->begin ([group callback])	710	=item $cv->begin ([group callback])
618		711
619	=item $cv->end	712	=item $cv->end
…		…
622	one. For example, a function that pings many hosts in parallel might want	715	one. For example, a function that pings many hosts in parallel might want
623	to use a condition variable for the whole process.	716	to use a condition variable for the whole process.
624		717
625	Every call to C<< ->begin >> will increment a counter, and every call to	718	Every call to C<< ->begin >> will increment a counter, and every call to
626	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	719	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
627	>>, the (last) callback passed to C<begin> will be executed. That callback	720	>>, the (last) callback passed to C<begin> will be executed, passing the
628	is I<supposed> to call C<< ->send >>, but that is not required. If no	721	condvar as first argument. That callback is I<supposed> to call C<< ->send
629	callback was set, C<send> will be called without any arguments.	722	>>, but that is not required. If no group callback was set, C<send> will
		723	be called without any arguments.
630		724
631	You can think of C<< $cv->send >> giving you an OR condition (one call	725	You can think of C<< $cv->send >> giving you an OR condition (one call
632	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND	726	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
633	condition (all C<begin> calls must be C<end>'ed before the condvar sends).	727	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
634		728
…		…
655	This works because for every event source (EOF on file handle), there is	749	This works because for every event source (EOF on file handle), there is
656	one call to C<begin>, so the condvar waits for all calls to C<end> before	750	one call to C<begin>, so the condvar waits for all calls to C<end> before
657	sending.	751	sending.
658		752
659	The ping example mentioned above is slightly more complicated, as the	753	The ping example mentioned above is slightly more complicated, as the
660	there are results to be passwd back, and the number of tasks that are	754	there are results to be passed back, and the number of tasks that are
661	begung can potentially be zero:	755	begun can potentially be zero:
662		756
663	my $cv = AnyEvent->condvar;	757	my $cv = AnyEvent->condvar;
664		758
665	my %result;	759	my %result;
666	$cv->begin (sub { $cv->send (\%result) });	760	$cv->begin (sub { shift->send (\%result) });
667		761
668	for my $host (@list_of_hosts) {	762	for my $host (@list_of_hosts) {
669	$cv->begin;	763	$cv->begin;
670	ping_host_then_call_callback $host, sub {	764	ping_host_then_call_callback $host, sub {
671	$result{$host} = ...;	765	$result{$host} = ...;
…		…
673	};	767	};
674	}	768	}
675		769
676	$cv->end;	770	$cv->end;
677		771
		772	...
		773
		774	my $results = $cv->recv;
		775
678	This code fragment supposedly pings a number of hosts and calls	776	This code fragment supposedly pings a number of hosts and calls
679	C<send> after results for all then have have been gathered - in any	777	C<send> after results for all then have have been gathered - in any
680	order. To achieve this, the code issues a call to C<begin> when it starts	778	order. To achieve this, the code issues a call to C<begin> when it starts
681	each ping request and calls C<end> when it has received some result for	779	each ping request and calls C<end> when it has received some result for
682	it. Since C<begin> and C<end> only maintain a counter, the order in which	780	it. Since C<begin> and C<end> only maintain a counter, the order in which
…		…
687	to be called once the counter reaches C<0>, and second, it ensures that	785	to be called once the counter reaches C<0>, and second, it ensures that
688	C<send> is called even when C<no> hosts are being pinged (the loop	786	C<send> is called even when C<no> hosts are being pinged (the loop
689	doesn't execute once).	787	doesn't execute once).
690		788
691	This is the general pattern when you "fan out" into multiple (but	789	This is the general pattern when you "fan out" into multiple (but
692	potentially none) subrequests: use an outer C<begin>/C<end> pair to set	790	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
693	the callback and ensure C<end> is called at least once, and then, for each	791	the callback and ensure C<end> is called at least once, and then, for each
694	subrequest you start, call C<begin> and for each subrequest you finish,	792	subrequest you start, call C<begin> and for each subrequest you finish,
695	call C<end>.	793	call C<end>.
696		794
697	=back	795	=back
…		…
704	=over 4	802	=over 4
705		803
706	=item $cv->recv	804	=item $cv->recv
707		805
708	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	806	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
709	>> methods have been called on c<$cv>, while servicing other watchers	807	>> methods have been called on C<$cv>, while servicing other watchers
710	normally.	808	normally.
711		809
712	You can only wait once on a condition - additional calls are valid but	810	You can only wait once on a condition - additional calls are valid but
713	will return immediately.	811	will return immediately.
714		812
…		…
717		815
718	In list context, all parameters passed to C<send> will be returned,	816	In list context, all parameters passed to C<send> will be returned,
719	in scalar context only the first one will be returned.	817	in scalar context only the first one will be returned.
720		818
721	Note that doing a blocking wait in a callback is not supported by any	819	Note that doing a blocking wait in a callback is not supported by any
722	event loop, that is, recursive invocation of a blocking C<< ->recv	820	event loop, that is, recursive invocation of a blocking C<< ->recv >> is
723	>> is not allowed, and the C<recv> call will C<croak> if such a	821	not allowed and the C<recv> call will C<croak> if such a condition is
724	condition is detected. This condition can be slightly loosened by using	822	detected. This requirement can be dropped by relying on L<Coro::AnyEvent>
725	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from	823	, which allows you to do a blocking C<< ->recv >> from any thread
726	any thread that doesn't run the event loop itself.	824	that doesn't run the event loop itself. L<Coro::AnyEvent> is loaded
		825	automatically when L<Coro> is used with L<AnyEvent>, so code does not need
		826	to do anything special to take advantage of that: any code that would
		827	normally block your program because it calls C<recv>, be executed in an
		828	C<async> thread instead without blocking other threads.
727		829
728	Not all event models support a blocking wait - some die in that case	830	Not all event models support a blocking wait - some die in that case
729	(programs might want to do that to stay interactive), so I<if you are	831	(programs might want to do that to stay interactive), so I<if you are
730	using this from a module, never require a blocking wait>. Instead, let the	832	using this from a module, never require a blocking wait>. Instead, let the
731	caller decide whether the call will block or not (for example, by coupling	833	caller decide whether the call will block or not (for example, by coupling
732	condition variables with some kind of request results and supporting	834	condition variables with some kind of request results and supporting
733	callbacks so the caller knows that getting the result will not block,	835	callbacks so the caller knows that getting the result will not block,
734	while still supporting blocking waits if the caller so desires).	836	while still supporting blocking waits if the caller so desires).
735		837
736	You can ensure that C<< -recv >> never blocks by setting a callback and	838	You can ensure that C<< ->recv >> never blocks by setting a callback and
737	only calling C<< ->recv >> from within that callback (or at a later	839	only calling C<< ->recv >> from within that callback (or at a later
738	time). This will work even when the event loop does not support blocking	840	time). This will work even when the event loop does not support blocking
739	waits otherwise.	841	waits otherwise.
740		842
741	=item $bool = $cv->ready	843	=item $bool = $cv->ready
…		…
747		849
748	This is a mutator function that returns the callback set and optionally	850	This is a mutator function that returns the callback set and optionally
749	replaces it before doing so.	851	replaces it before doing so.
750		852
751	The callback will be called when the condition becomes "true", i.e. when	853	The callback will be called when the condition becomes "true", i.e. when
752	C<send> or C<croak> are called, with the only argument being the condition	854	C<send> or C<croak> are called, with the only argument being the
753	variable itself. Calling C<recv> inside the callback or at any later time	855	condition variable itself. If the condition is already true, the
754	is guaranteed not to block.	856	callback is called immediately when it is set. Calling C<recv> inside
		857	the callback or at any later time is guaranteed not to block.
755		858
756	=back	859	=back
757		860
758	=head1 SUPPORTED EVENT LOOPS/BACKENDS	861	=head1 SUPPORTED EVENT LOOPS/BACKENDS
759		862
…		…
762	=over 4	865	=over 4
763		866
764	=item Backends that are autoprobed when no other event loop can be found.	867	=item Backends that are autoprobed when no other event loop can be found.
765		868
766	EV is the preferred backend when no other event loop seems to be in	869	EV is the preferred backend when no other event loop seems to be in
767	use. If EV is not installed, then AnyEvent will try Event, and, failing	870	use. If EV is not installed, then AnyEvent will fall back to its own
768	that, will fall back to its own pure-perl implementation, which is	871	pure-perl implementation, which is available everywhere as it comes with
769	available everywhere as it comes with AnyEvent itself.	872	AnyEvent itself.
770		873
771	AnyEvent::Impl::EV based on EV (interface to libev, best choice).	874	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
772	AnyEvent::Impl::Event based on Event, very stable, few glitches.
773	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	875	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
774		876
775	=item Backends that are transparently being picked up when they are used.	877	=item Backends that are transparently being picked up when they are used.
776		878
777	These will be used when they are currently loaded when the first watcher	879	These will be used if they are already loaded when the first watcher
778	is created, in which case it is assumed that the application is using	880	is created, in which case it is assumed that the application is using
779	them. This means that AnyEvent will automatically pick the right backend	881	them. This means that AnyEvent will automatically pick the right backend
780	when the main program loads an event module before anything starts to	882	when the main program loads an event module before anything starts to
781	create watchers. Nothing special needs to be done by the main program.	883	create watchers. Nothing special needs to be done by the main program.
782		884
		885	AnyEvent::Impl::Event based on Event, very stable, few glitches.
783	AnyEvent::Impl::Glib based on Glib, slow but very stable.	886	AnyEvent::Impl::Glib based on Glib, slow but very stable.
784	AnyEvent::Impl::Tk based on Tk, very broken.	887	AnyEvent::Impl::Tk based on Tk, very broken.
		888	AnyEvent::Impl::UV based on UV, innovated square wheels.
785	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	889	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
786	AnyEvent::Impl::POE based on POE, very slow, some limitations.	890	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		891	AnyEvent::Impl::Irssi used when running within irssi.
		892	AnyEvent::Impl::IOAsync based on IO::Async.
		893	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		894	AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding).
787		895
788	=item Backends with special needs.	896	=item Backends with special needs.
789		897
790	Qt requires the Qt::Application to be instantiated first, but will	898	Qt requires the Qt::Application to be instantiated first, but will
791	otherwise be picked up automatically. As long as the main program	899	otherwise be picked up automatically. As long as the main program
792	instantiates the application before any AnyEvent watchers are created,	900	instantiates the application before any AnyEvent watchers are created,
793	everything should just work.	901	everything should just work.
794		902
795	AnyEvent::Impl::Qt based on Qt.	903	AnyEvent::Impl::Qt based on Qt.
796		904
797	Support for IO::Async can only be partial, as it is too broken and
798	architecturally limited to even support the AnyEvent API. It also
799	is the only event loop that needs the loop to be set explicitly, so
800	it can only be used by a main program knowing about AnyEvent. See
801	L<AnyEvent::Impl::Async> for the gory details.
802
803	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
804
805	=item Event loops that are indirectly supported via other backends.	905	=item Event loops that are indirectly supported via other backends.
806		906
807	Some event loops can be supported via other modules:	907	Some event loops can be supported via other modules:
808		908
809	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.	909	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
…		…
834	Contains C<undef> until the first watcher is being created, before the	934	Contains C<undef> until the first watcher is being created, before the
835	backend has been autodetected.	935	backend has been autodetected.
836		936
837	Afterwards it contains the event model that is being used, which is the	937	Afterwards it contains the event model that is being used, which is the
838	name of the Perl class implementing the model. This class is usually one	938	name of the Perl class implementing the model. This class is usually one
839	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the	939	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
840	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it	940	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
841	will be C<urxvt::anyevent>).	941	will be C<urxvt::anyevent>).
842		942
843	=item AnyEvent::detect	943	=item AnyEvent::detect
844		944
845	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	945	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
846	if necessary. You should only call this function right before you would	946	if necessary. You should only call this function right before you would
847	have created an AnyEvent watcher anyway, that is, as late as possible at	947	have created an AnyEvent watcher anyway, that is, as late as possible at
848	runtime, and not e.g. while initialising of your module.	948	runtime, and not e.g. during initialisation of your module.
		949
		950	The effect of calling this function is as if a watcher had been created
		951	(specifically, actions that happen "when the first watcher is created"
		952	happen when calling detetc as well).
849		953
850	If you need to do some initialisation before AnyEvent watchers are	954	If you need to do some initialisation before AnyEvent watchers are
851	created, use C<post_detect>.	955	created, use C<post_detect>.
852		956
853	=item $guard = AnyEvent::post_detect { BLOCK }	957	=item $guard = AnyEvent::post_detect { BLOCK }
854		958
855	Arranges for the code block to be executed as soon as the event model is	959	Arranges for the code block to be executed as soon as the event model is
856	autodetected (or immediately if this has already happened).	960	autodetected (or immediately if that has already happened).
857		961
858	The block will be executed I<after> the actual backend has been detected	962	The block will be executed I<after> the actual backend has been detected
859	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been	963	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
860	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do	964	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
861	other initialisations - see the sources of L<AnyEvent::Strict> or	965	other initialisations - see the sources of L<AnyEvent::Strict> or
…		…
865	event module detection too early, for example, L<AnyEvent::AIO> creates	969	event module detection too early, for example, L<AnyEvent::AIO> creates
866	and installs the global L<IO::AIO> watcher in a C<post_detect> block to	970	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
867	avoid autodetecting the event module at load time.	971	avoid autodetecting the event module at load time.
868		972
869	If called in scalar or list context, then it creates and returns an object	973	If called in scalar or list context, then it creates and returns an object
870	that automatically removes the callback again when it is destroyed. See	974	that automatically removes the callback again when it is destroyed (or
		975	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
871	L<Coro::BDB> for a case where this is useful.	976	a case where this is useful.
		977
		978	Example: Create a watcher for the IO::AIO module and store it in
		979	C<$WATCHER>, but do so only do so after the event loop is initialised.
		980
		981	our WATCHER;
		982
		983	my $guard = AnyEvent::post_detect {
		984	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		985	};
		986
		987	# the ||= is important in case post_detect immediately runs the block,
		988	# as to not clobber the newly-created watcher. assigning both watcher and
		989	# post_detect guard to the same variable has the advantage of users being
		990	# able to just C<undef $WATCHER> if the watcher causes them grief.
		991
		992	$WATCHER ||= $guard;
872		993
873	=item @AnyEvent::post_detect	994	=item @AnyEvent::post_detect
874		995
875	If there are any code references in this array (you can C<push> to it	996	If there are any code references in this array (you can C<push> to it
876	before or after loading AnyEvent), then they will called directly after	997	before or after loading AnyEvent), then they will be called directly
877	the event loop has been chosen.	998	after the event loop has been chosen.
878		999
879	You should check C<$AnyEvent::MODEL> before adding to this array, though:	1000	You should check C<$AnyEvent::MODEL> before adding to this array, though:
880	if it is defined then the event loop has already been detected, and the	1001	if it is defined then the event loop has already been detected, and the
881	array will be ignored.	1002	array will be ignored.
882		1003
883	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows	1004	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
884	it,as it takes care of these details.	1005	it, as it takes care of these details.
885		1006
886	This variable is mainly useful for modules that can do something useful	1007	This variable is mainly useful for modules that can do something useful
887	when AnyEvent is used and thus want to know when it is initialised, but do	1008	when AnyEvent is used and thus want to know when it is initialised, but do
888	not need to even load it by default. This array provides the means to hook	1009	not need to even load it by default. This array provides the means to hook
889	into AnyEvent passively, without loading it.	1010	into AnyEvent passively, without loading it.
890		1011
		1012	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1013	together, you could put this into Coro (this is the actual code used by
		1014	Coro to accomplish this):
		1015
		1016	if (defined $AnyEvent::MODEL) {
		1017	# AnyEvent already initialised, so load Coro::AnyEvent
		1018	require Coro::AnyEvent;
		1019	} else {
		1020	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1021	# as soon as it is
		1022	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1023	}
		1024
		1025	=item AnyEvent::postpone { BLOCK }
		1026
		1027	Arranges for the block to be executed as soon as possible, but not before
		1028	the call itself returns. In practise, the block will be executed just
		1029	before the event loop polls for new events, or shortly afterwards.
		1030
		1031	This function never returns anything (to make the C<return postpone { ...
		1032	}> idiom more useful.
		1033
		1034	To understand the usefulness of this function, consider a function that
		1035	asynchronously does something for you and returns some transaction
		1036	object or guard to let you cancel the operation. For example,
		1037	C<AnyEvent::Socket::tcp_connect>:
		1038
		1039	# start a connection attempt unless one is active
		1040	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1041	delete $self->{connect_guard};
		1042	...
		1043	};
		1044
		1045	Imagine that this function could instantly call the callback, for
		1046	example, because it detects an obvious error such as a negative port
		1047	number. Invoking the callback before the function returns causes problems
		1048	however: the callback will be called and will try to delete the guard
		1049	object. But since the function hasn't returned yet, there is nothing to
		1050	delete. When the function eventually returns it will assign the guard
		1051	object to C<< $self->{connect_guard} >>, where it will likely never be
		1052	deleted, so the program thinks it is still trying to connect.
		1053
		1054	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1055	callback directly on error:
		1056
		1057	$cb->(undef), return # signal error to callback, BAD!
		1058	if $some_error_condition;
		1059
		1060	It should use C<postpone>:
		1061
		1062	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1063	if $some_error_condition;
		1064
		1065	=item AnyEvent::log $level, $msg[, @args]
		1066
		1067	Log the given C<$msg> at the given C<$level>.
		1068
		1069	If L<AnyEvent::Log> is not loaded then this function makes a simple test
		1070	to see whether the message will be logged. If the test succeeds it will
		1071	load AnyEvent::Log and call C<AnyEvent::Log::log> - consequently, look at
		1072	the L<AnyEvent::Log> documentation for details.
		1073
		1074	If the test fails it will simply return. Right now this happens when a
		1075	numerical loglevel is used and it is larger than the level specified via
		1076	C<$ENV{PERL_ANYEVENT_VERBOSE}>.
		1077
		1078	If you want to sprinkle loads of logging calls around your code, consider
		1079	creating a logger callback with the C<AnyEvent::Log::logger> function,
		1080	which can reduce typing, codesize and can reduce the logging overhead
		1081	enourmously.
		1082
891	=back	1083	=back
892		1084
893	=head1 WHAT TO DO IN A MODULE	1085	=head1 WHAT TO DO IN A MODULE
894		1086
895	As a module author, you should C<use AnyEvent> and call AnyEvent methods	1087	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
905	because it will stall the whole program, and the whole point of using	1097	because it will stall the whole program, and the whole point of using
906	events is to stay interactive.	1098	events is to stay interactive.
907		1099
908	It is fine, however, to call C<< ->recv >> when the user of your module	1100	It is fine, however, to call C<< ->recv >> when the user of your module
909	requests it (i.e. if you create a http request object ad have a method	1101	requests it (i.e. if you create a http request object ad have a method
910	called C<results> that returns the results, it should call C<< ->recv >>	1102	called C<results> that returns the results, it may call C<< ->recv >>
911	freely, as the user of your module knows what she is doing. always).	1103	freely, as the user of your module knows what she is doing. Always).
912		1104
913	=head1 WHAT TO DO IN THE MAIN PROGRAM	1105	=head1 WHAT TO DO IN THE MAIN PROGRAM
914		1106
915	There will always be a single main program - the only place that should	1107	There will always be a single main program - the only place that should
916	dictate which event model to use.	1108	dictate which event model to use.
917		1109
918	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1110	If the program is not event-based, it need not do anything special, even
919	do anything special (it does not need to be event-based) and let AnyEvent	1111	when it depends on a module that uses an AnyEvent. If the program itself
920	decide which implementation to chose if some module relies on it.	1112	uses AnyEvent, but does not care which event loop is used, all it needs
		1113	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1114	available loop implementation.
921		1115
922	If the main program relies on a specific event model - for example, in	1116	If the main program relies on a specific event model - for example, in
923	Gtk2 programs you have to rely on the Glib module - you should load the	1117	Gtk2 programs you have to rely on the Glib module - you should load the
924	event module before loading AnyEvent or any module that uses it: generally	1118	event module before loading AnyEvent or any module that uses it: generally
925	speaking, you should load it as early as possible. The reason is that	1119	speaking, you should load it as early as possible. The reason is that
926	modules might create watchers when they are loaded, and AnyEvent will	1120	modules might create watchers when they are loaded, and AnyEvent will
927	decide on the event model to use as soon as it creates watchers, and it	1121	decide on the event model to use as soon as it creates watchers, and it
928	might chose the wrong one unless you load the correct one yourself.	1122	might choose the wrong one unless you load the correct one yourself.
929		1123
930	You can chose to use a pure-perl implementation by loading the	1124	You can chose to use a pure-perl implementation by loading the
931	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1125	C<AnyEvent::Loop> module, which gives you similar behaviour
932	everywhere, but letting AnyEvent chose the model is generally better.	1126	everywhere, but letting AnyEvent chose the model is generally better.
933		1127
934	=head2 MAINLOOP EMULATION	1128	=head2 MAINLOOP EMULATION
935		1129
936	Sometimes (often for short test scripts, or even standalone programs who	1130	Sometimes (often for short test scripts, or even standalone programs who
…		…
949		1143
950		1144
951	=head1 OTHER MODULES	1145	=head1 OTHER MODULES
952		1146
953	The following is a non-exhaustive list of additional modules that use	1147	The following is a non-exhaustive list of additional modules that use
954	AnyEvent as a client and can therefore be mixed easily with other AnyEvent	1148	AnyEvent as a client and can therefore be mixed easily with other
955	modules and other event loops in the same program. Some of the modules	1149	AnyEvent modules and other event loops in the same program. Some of the
956	come with AnyEvent, most are available via CPAN.	1150	modules come as part of AnyEvent, the others are available via CPAN (see
		1151	L<http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for
		1152	a longer non-exhaustive list), and the list is heavily biased towards
		1153	modules of the AnyEvent author himself :)
957		1154
958	=over 4	1155	=over 4
959		1156
960	=item L<AnyEvent::Util>	1157	=item L<AnyEvent::Util> (part of the AnyEvent distribution)
961		1158
962	Contains various utility functions that replace often-used but blocking	1159	Contains various utility functions that replace often-used blocking
963	functions such as C<inet_aton> by event-/callback-based versions.	1160	functions such as C<inet_aton> with event/callback-based versions.
964		1161
965	=item L<AnyEvent::Socket>	1162	=item L<AnyEvent::Socket> (part of the AnyEvent distribution)
966		1163
967	Provides various utility functions for (internet protocol) sockets,	1164	Provides various utility functions for (internet protocol) sockets,
968	addresses and name resolution. Also functions to create non-blocking tcp	1165	addresses and name resolution. Also functions to create non-blocking tcp
969	connections or tcp servers, with IPv6 and SRV record support and more.	1166	connections or tcp servers, with IPv6 and SRV record support and more.
970		1167
971	=item L<AnyEvent::Handle>	1168	=item L<AnyEvent::Handle> (part of the AnyEvent distribution)
972		1169
973	Provide read and write buffers, manages watchers for reads and writes,	1170	Provide read and write buffers, manages watchers for reads and writes,
974	supports raw and formatted I/O, I/O queued and fully transparent and	1171	supports raw and formatted I/O, I/O queued and fully transparent and
975	non-blocking SSL/TLS (via L<AnyEvent::TLS>.	1172	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
976		1173
977	=item L<AnyEvent::DNS>	1174	=item L<AnyEvent::DNS> (part of the AnyEvent distribution)
978		1175
979	Provides rich asynchronous DNS resolver capabilities.	1176	Provides rich asynchronous DNS resolver capabilities.
980		1177
981	=item L<AnyEvent::HTTP>	1178	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
982		1179
983	A simple-to-use HTTP library that is capable of making a lot of concurrent	1180	Implement event-based interfaces to the protocols of the same name (for
984	HTTP requests.	1181	the curious, IGS is the International Go Server and FCP is the Freenet
		1182	Client Protocol).
985		1183
		1184	=item L<AnyEvent::AIO> (part of the AnyEvent distribution)
		1185
		1186	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1187	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1188	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1189	file I/O, and much more.
		1190
		1191	=item L<AnyEvent::Fork>, L<AnyEvent::Fork::RPC>, L<AnyEvent::Fork::Pool>, L<AnyEvent::Fork::Remote>
		1192
		1193	These let you safely fork new subprocesses, either locally or
		1194	remotely (e.g.v ia ssh), using some RPC protocol or not, without
		1195	the limitations normally imposed by fork (AnyEvent works fine for
		1196	example). Dynamically-resized worker pools are obviously included as well.
		1197
		1198	And they are quite tiny and fast as well - "abusing" L<AnyEvent::Fork>
		1199	just to exec external programs can easily beat using C<fork> and C<exec>
		1200	(or even C<system>) in most programs.
		1201
		1202	=item L<AnyEvent::Filesys::Notify>
		1203
		1204	AnyEvent is good for non-blocking stuff, but it can't detect file or
		1205	path changes (e.g. "watch this directory for new files", "watch this
		1206	file for changes"). The L<AnyEvent::Filesys::Notify> module promises to
		1207	do just that in a portbale fashion, supporting inotify on GNU/Linux and
		1208	some weird, without doubt broken, stuff on OS X to monitor files. It can
		1209	fall back to blocking scans at regular intervals transparently on other
		1210	platforms, so it's about as portable as it gets.
		1211
		1212	(I haven't used it myself, but it seems the biggest problem with it is
		1213	it quite bad performance).
		1214
986	=item L<AnyEvent::HTTPD>	1215	=item L<AnyEvent::DBI>
987		1216
988	Provides a simple web application server framework.	1217	Executes L<DBI> requests asynchronously in a proxy process for you,
		1218	notifying you in an event-based way when the operation is finished.
989		1219
990	=item L<AnyEvent::FastPing>	1220	=item L<AnyEvent::FastPing>
991		1221
992	The fastest ping in the west.	1222	The fastest ping in the west.
993		1223
994	=item L<AnyEvent::DBI>
995
996	Executes L<DBI> requests asynchronously in a proxy process.
997
998	=item L<AnyEvent::AIO>
999
1000	Truly asynchronous I/O, should be in the toolbox of every event
1001	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
1002	together.
1003
1004	=item L<AnyEvent::BDB>
1005
1006	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
1007	L<BDB> and AnyEvent together.
1008
1009	=item L<AnyEvent::GPSD>
1010
1011	A non-blocking interface to gpsd, a daemon delivering GPS information.
1012
1013	=item L<AnyEvent::IRC>
1014
1015	AnyEvent based IRC client module family (replacing the older Net::IRC3).
1016
1017	=item L<AnyEvent::XMPP>
1018
1019	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
1020	Net::XMPP2>.
1021
1022	=item L<AnyEvent::IGS>
1023
1024	A non-blocking interface to the Internet Go Server protocol (used by
1025	L<App::IGS>).
1026
1027	=item L<Net::FCP>
1028
1029	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
1030	of AnyEvent.
1031
1032	=item L<Event::ExecFlow>
1033
1034	High level API for event-based execution flow control.
1035
1036	=item L<Coro>	1224	=item L<Coro>
1037		1225
1038	Has special support for AnyEvent via L<Coro::AnyEvent>.	1226	Has special support for AnyEvent via L<Coro::AnyEvent>, which allows you
		1227	to simply invert the flow control - don't call us, we will call you:
		1228
		1229	async {
		1230	Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
		1231	print "5 seconds later!\n";
		1232
		1233	Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
		1234	my $line = <STDIN>; # works for ttys
		1235
		1236	AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
		1237	my ($body, $hdr) = Coro::rouse_wait;
		1238	};
1039		1239
1040	=back	1240	=back
1041		1241
1042	=cut	1242	=cut
1043		1243
1044	package AnyEvent;	1244	package AnyEvent;
1045		1245
1046	# basically a tuned-down version of common::sense	1246	BEGIN {
1047	sub common_sense {	1247	require "AnyEvent/constants.pl";
1048	# no warnings	1248	&AnyEvent::common_sense;
1049	${^WARNING_BITS} ^= ${^WARNING_BITS};
1050	# use strict vars subs
1051	$^H |= 0x00000600;
1052	}	1249	}
1053
1054	BEGIN { AnyEvent::common_sense }
1055		1250
1056	use Carp ();	1251	use Carp ();
1057		1252
1058	our $VERSION = 4.83;	1253	our $VERSION = '7.08';
1059	our $MODEL;	1254	our $MODEL;
1060
1061	our $AUTOLOAD;
1062	our @ISA;	1255	our @ISA;
1063
1064	our @REGISTRY;	1256	our @REGISTRY;
1065
1066	our $WIN32;
1067
1068	our $VERBOSE;	1257	our $VERBOSE;
		1258	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		1259	our $MAX_SIGNAL_LATENCY = $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} || 10; # executes after the BEGIN block below (tainting!)
1069		1260
1070	BEGIN {	1261	BEGIN {
1071	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
1072	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";	1262	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
1073		1263
1074	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}	1264	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1075	if ${^TAINT};	1265	if ${^TAINT};
1076		1266
1077	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1267	$ENV{"PERL_ANYEVENT_$_"} = $ENV{"AE_$_"}
		1268	for grep s/^AE_// && !exists $ENV{"PERL_ANYEVENT_$_"}, keys %ENV;
1078		1269
1079	}	1270	@ENV{grep /^PERL_ANYEVENT_/, keys %ENV} = ()
		1271	if ${^TAINT};
1080		1272
1081	our $MAX_SIGNAL_LATENCY = 10;	1273	# $ENV{PERL_ANYEVENT_xxx} now valid
1082		1274
1083	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1275	$VERBOSE = length $ENV{PERL_ANYEVENT_VERBOSE} ? $ENV{PERL_ANYEVENT_VERBOSE}*1 : 4;
1084		1276
1085	{
1086	my $idx;	1277	my $idx;
1087	$PROTOCOL{$_} = ++$idx	1278	$PROTOCOL{$_} = ++$idx
1088	for reverse split /\s*,\s*/,	1279	for reverse split /\s*,\s*/,
1089	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1280	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
1090	}	1281	}
1091		1282
		1283	our @post_detect;
		1284
		1285	sub post_detect(&) {
		1286	my ($cb) = @_;
		1287
		1288	push @post_detect, $cb;
		1289
		1290	defined wantarray
		1291	? bless \$cb, "AnyEvent::Util::postdetect"
		1292	: ()
		1293	}
		1294
		1295	sub AnyEvent::Util::postdetect::DESTROY {
		1296	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1297	}
		1298
		1299	our $POSTPONE_W;
		1300	our @POSTPONE;
		1301
		1302	sub _postpone_exec {
		1303	undef $POSTPONE_W;
		1304
		1305	&{ shift @POSTPONE }
		1306	while @POSTPONE;
		1307	}
		1308
		1309	sub postpone(&) {
		1310	push @POSTPONE, shift;
		1311
		1312	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1313
		1314	()
		1315	}
		1316
		1317	sub log($$;@) {
		1318	# only load the big bloated module when we actually are about to log something
		1319	if ($_[0] <= ($VERBOSE || 1)) { # also catches non-numeric levels(!) and fatal
		1320	local ($!, $@);
		1321	require AnyEvent::Log; # among other things, sets $VERBOSE to 9
		1322	# AnyEvent::Log overwrites this function
		1323	goto &log;
		1324	}
		1325
		1326	0 # not logged
		1327	}
		1328
		1329	sub _logger($;$) {
		1330	my ($level, $renabled) = @_;
		1331
		1332	$$renabled = $level <= $VERBOSE;
		1333
		1334	my $logger = [(caller)[0], $level, $renabled];
		1335
		1336	$AnyEvent::Log::LOGGER{$logger+0} = $logger;
		1337
		1338	# return unless defined wantarray;
		1339	#
		1340	# require AnyEvent::Util;
		1341	# my $guard = AnyEvent::Util::guard (sub {
		1342	# # "clean up"
		1343	# delete $LOGGER{$logger+0};
		1344	# });
		1345	#
		1346	# sub {
		1347	# return 0 unless $$renabled;
		1348	#
		1349	# $guard if 0; # keep guard alive, but don't cause runtime overhead
		1350	# require AnyEvent::Log unless $AnyEvent::Log::VERSION;
		1351	# package AnyEvent::Log;
		1352	# _log ($logger->[0], $level, @_) # logger->[0] has been converted at load time
		1353	# }
		1354	}
		1355
		1356	if (length $ENV{PERL_ANYEVENT_LOG}) {
		1357	require AnyEvent::Log; # AnyEvent::Log does the thing for us
		1358	}
		1359
1092	my @models = (	1360	our @models = (
1093	[EV:: => AnyEvent::Impl::EV::],	1361	[EV:: => AnyEvent::Impl::EV::],
1094	[Event:: => AnyEvent::Impl::Event::],
1095	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1362	[AnyEvent::Loop:: => AnyEvent::Impl::Perl::],
1096	# everything below here will not be autoprobed	1363	# everything below here will not (normally) be autoprobed
1097	# as the pureperl backend should work everywhere	1364	# as the pure perl backend should work everywhere
1098	# and is usually faster	1365	# and is usually faster
		1366	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package, so msut be near the top
		1367	[Event:: => AnyEvent::Impl::Event::], # slow, stable
1099	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1368	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1369	# everything below here should not be autoloaded
1100	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1370	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
1101	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1371	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1372	[UV:: => AnyEvent::Impl::UV::], # switched from libev, added back all bugs imaginable
1102	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1373	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1103	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1374	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
1104	[Wx:: => AnyEvent::Impl::POE::],	1375	[Wx:: => AnyEvent::Impl::POE::],
1105	[Prima:: => AnyEvent::Impl::POE::],	1376	[Prima:: => AnyEvent::Impl::POE::],
1106	# IO::Async is just too broken - we would need workarounds for its	1377	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
1107	# byzantine signal and broken child handling, among others.	1378	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
1108	# IO::Async is rather hard to detect, as it doesn't have any	1379	[FLTK:: => AnyEvent::Impl::FLTK::],
1109	# obvious default class.
1110	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1111	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
1112	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
1113	);	1380	);
1114		1381
1115	our %method = map +($_ => 1),	1382	our @isa_hook;
		1383
		1384	sub _isa_set {
		1385	my @pkg = ("AnyEvent", (map $_->[0], grep defined, @isa_hook), $MODEL);
		1386
		1387	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1388	for 1 .. $#pkg;
		1389
		1390	grep $_ && $_->[1], @isa_hook
		1391	and AE::_reset ();
		1392	}
		1393
		1394	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1395	sub _isa_hook($$;$) {
		1396	my ($i, $pkg, $reset_ae) = @_;
		1397
		1398	$isa_hook[$i] = $pkg ? [$pkg, $reset_ae] : undef;
		1399
		1400	_isa_set;
		1401	}
		1402
		1403	# all autoloaded methods reserve the complete glob, not just the method slot.
		1404	# due to bugs in perls method cache implementation.
1116	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1405	our @methods = qw(io timer time now now_update signal child idle condvar);
1117		1406
1118	our @post_detect;
1119
1120	sub post_detect(&) {	1407	sub detect() {
1121	my ($cb) = @_;	1408	return $MODEL if $MODEL; # some programs keep references to detect
1122		1409
1123	if ($MODEL) {	1410	# IO::Async::Loop::AnyEvent is extremely evil, refuse to work with it
1124	$cb->();	1411	# the author knows about the problems and what it does to AnyEvent as a whole
		1412	# (and the ability of others to use AnyEvent), but simply wants to abuse AnyEvent
		1413	# anyway.
		1414	AnyEvent::log fatal => "IO::Async::Loop::AnyEvent detected - that module is broken by\n"
		1415	. "design, abuses internals and breaks AnyEvent - will not continue."
		1416	if exists $INC{"IO/Async/Loop/AnyEvent.pm"};
1125		1417
1126	1	1418	local $!; # for good measure
		1419	local $SIG{__DIE__}; # we use eval
		1420
		1421	# free some memory
		1422	*detect = sub () { $MODEL };
		1423	# undef &func doesn't correctly update the method cache. grmbl.
		1424	# so we delete the whole glob. grmbl.
		1425	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1426	# a glob with an active sub. hrm. i hope it works, but perl is
		1427	# usually buggy in this department. sigh.
		1428	delete @{"AnyEvent::"}{@methods};
		1429	undef @methods;
		1430
		1431	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1432	my $model = $1;
		1433	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1434	if (eval "require $model") {
		1435	AnyEvent::log 7 => "Loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.";
		1436	$MODEL = $model;
1127	} else {	1437	} else {
1128	push @post_detect, $cb;	1438	AnyEvent::log 4 => "Unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
1129		1439	}
1130	defined wantarray
1131	? bless \$cb, "AnyEvent::Util::postdetect"
1132	: ()
1133	}	1440	}
1134	}
1135		1441
1136	sub AnyEvent::Util::postdetect::DESTROY {	1442	# check for already loaded models
1137	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1138	}
1139
1140	sub detect() {
1141	unless ($MODEL) {	1443	unless ($MODEL) {
1142	local $SIG{__DIE__};	1444	for (@REGISTRY, @models) {
1143		1445	my ($package, $model) = @$_;
1144	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1446	if (${"$package\::VERSION"} > 0) {
1145	my $model = "AnyEvent::Impl::$1";
1146	if (eval "require $model") {	1447	if (eval "require $model") {
		1448	AnyEvent::log 7 => "Autodetected model '$model', using it.";
1147	$MODEL = $model;	1449	$MODEL = $model;
1148	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;	1450	last;
1149	} else {	1451	} else {
1150	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;	1452	AnyEvent::log 8 => "Detected event loop $package, but cannot load '$model', skipping: $@";
		1453	}
1151	}	1454	}
1152	}	1455	}
1153		1456
1154	# check for already loaded models
1155	unless ($MODEL) {	1457	unless ($MODEL) {
		1458	# try to autoload a model
1156	for (@REGISTRY, @models) {	1459	for (@REGISTRY, @models) {
1157	my ($package, $model) = @$_;	1460	my ($package, $model) = @$_;
		1461	if (
		1462	eval "require $package"
1158	if (${"$package\::VERSION"} > 0) {	1463	and ${"$package\::VERSION"} > 0
1159	if (eval "require $model") {	1464	and eval "require $model"
		1465	) {
		1466	AnyEvent::log 7 => "Autoloaded model '$model', using it.";
1160	$MODEL = $model;	1467	$MODEL = $model;
1161	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1162	last;	1468	last;
1163	}
1164	}	1469	}
1165	}	1470	}
1166		1471
1167	unless ($MODEL) {
1168	# try to load a model
1169
1170	for (@REGISTRY, @models) {
1171	my ($package, $model) = @$_;
1172	if (eval "require $package"
1173	and ${"$package\::VERSION"} > 0
1174	and eval "require $model") {
1175	$MODEL = $model;
1176	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
1177	last;
1178	}
1179	}
1180
1181	$MODEL	1472	$MODEL
1182	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";	1473	or AnyEvent::log fatal => "Backend autodetection failed - did you properly install AnyEvent?";
1183	}
1184	}	1474	}
1185
1186	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1187
1188	unshift @ISA, $MODEL;
1189
1190	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1191
1192	(shift @post_detect)->() while @post_detect;
1193	}	1475	}
1194		1476
		1477	# free memory only needed for probing
		1478	undef @models;
		1479	undef @REGISTRY;
		1480
		1481	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1482
		1483	# now nuke some methods that are overridden by the backend.
		1484	# SUPER usage is not allowed in these.
		1485	for (qw(time signal child idle)) {
		1486	undef &{"AnyEvent::Base::$_"}
		1487	if defined &{"$MODEL\::$_"};
		1488	}
		1489
		1490	_isa_set;
		1491
		1492	# we're officially open!
		1493
		1494	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1495	require AnyEvent::Strict;
		1496	}
		1497
		1498	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1499	require AnyEvent::Debug;
		1500	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1501	}
		1502
		1503	if (length $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1504	require AnyEvent::Socket;
		1505	require AnyEvent::Debug;
		1506
		1507	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1508	$shell =~ s/\$\$/$$/g;
		1509
		1510	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1511	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1512	}
		1513
		1514	# now the anyevent environment is set up as the user told us to, so
		1515	# call the actual user code - post detects
		1516
		1517	(shift @post_detect)->() while @post_detect;
		1518	undef @post_detect;
		1519
		1520	*post_detect = sub(&) {
		1521	shift->();
		1522
		1523	undef
		1524	};
		1525
1195	$MODEL	1526	$MODEL
1196	}	1527	}
1197		1528
1198	sub AUTOLOAD {	1529	for my $name (@methods) {
1199	(my $func = $AUTOLOAD) =~ s/.*://;	1530	*$name = sub {
1200		1531	detect;
1201	$method{$func}	1532	# we use goto because
1202	or Carp::croak "$func: not a valid method for AnyEvent objects";	1533	# a) it makes the thunk more transparent
1203		1534	# b) it allows us to delete the thunk later
1204	detect unless $MODEL;	1535	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
1205		1536	};
1206	my $class = shift;
1207	$class->$func (@_);
1208	}	1537	}
1209		1538
1210	# utility function to dup a filehandle. this is used by many backends	1539	# utility function to dup a filehandle. this is used by many backends
1211	# to support binding more than one watcher per filehandle (they usually	1540	# to support binding more than one watcher per filehandle (they usually
1212	# allow only one watcher per fd, so we dup it to get a different one).	1541	# allow only one watcher per fd, so we dup it to get a different one).
…		…
1222	# we assume CLOEXEC is already set by perl in all important cases	1551	# we assume CLOEXEC is already set by perl in all important cases
1223		1552
1224	($fh2, $rw)	1553	($fh2, $rw)
1225	}	1554	}
1226		1555
		1556	=head1 SIMPLIFIED AE API
		1557
		1558	Starting with version 5.0, AnyEvent officially supports a second, much
		1559	simpler, API that is designed to reduce the calling, typing and memory
		1560	overhead by using function call syntax and a fixed number of parameters.
		1561
		1562	See the L<AE> manpage for details.
		1563
		1564	=cut
		1565
		1566	package AE;
		1567
		1568	our $VERSION = $AnyEvent::VERSION;
		1569
		1570	sub _reset() {
		1571	eval q{
		1572	# fall back to the main API by default - backends and AnyEvent::Base
		1573	# implementations can overwrite these.
		1574
		1575	sub io($$$) {
		1576	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1577	}
		1578
		1579	sub timer($$$) {
		1580	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1581	}
		1582
		1583	sub signal($$) {
		1584	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1585	}
		1586
		1587	sub child($$) {
		1588	AnyEvent->child (pid => $_[0], cb => $_[1])
		1589	}
		1590
		1591	sub idle($) {
		1592	AnyEvent->idle (cb => $_[0]);
		1593	}
		1594
		1595	sub cv(;&) {
		1596	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1597	}
		1598
		1599	sub now() {
		1600	AnyEvent->now
		1601	}
		1602
		1603	sub now_update() {
		1604	AnyEvent->now_update
		1605	}
		1606
		1607	sub time() {
		1608	AnyEvent->time
		1609	}
		1610
		1611	*postpone = \&AnyEvent::postpone;
		1612	*log = \&AnyEvent::log;
		1613	};
		1614	die if $@;
		1615	}
		1616
		1617	BEGIN { _reset }
		1618
1227	package AnyEvent::Base;	1619	package AnyEvent::Base;
1228		1620
1229	# default implementations for many methods	1621	# default implementations for many methods
1230		1622
1231	sub _time {	1623	sub time {
		1624	eval q{ # poor man's autoloading {}
1232	# probe for availability of Time::HiRes	1625	# probe for availability of Time::HiRes
1233	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1626	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
1234	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;	1627	*time = sub { Time::HiRes::time () };
1235	*_time = \&Time::HiRes::time;	1628	*AE::time = \& Time::HiRes::time ;
		1629	*now = \&time;
		1630	AnyEvent::log 8 => "using Time::HiRes for sub-second timing accuracy.";
1236	# if (eval "use POSIX (); (POSIX::times())...	1631	# if (eval "use POSIX (); (POSIX::times())...
1237	} else {	1632	} else {
1238	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;	1633	*time = sub { CORE::time };
1239	*_time = sub { time }; # epic fail	1634	*AE::time = sub (){ CORE::time };
		1635	*now = \&time;
		1636	AnyEvent::log 3 => "Using built-in time(), no sub-second resolution!";
		1637	}
1240	}	1638	};
		1639	die if $@;
1241		1640
1242	&_time	1641	&time
1243	}	1642	}
1244		1643
1245	sub time { _time }	1644	*now = \&time;
1246	sub now { _time }
1247	sub now_update { }	1645	sub now_update { }
1248		1646
		1647	sub _poll {
		1648	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1649	}
		1650
1249	# default implementation for ->condvar	1651	# default implementation for ->condvar
		1652	# in fact, the default should not be overwritten
1250		1653
1251	sub condvar {	1654	sub condvar {
		1655	eval q{ # poor man's autoloading {}
		1656	*condvar = sub {
1252	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"	1657	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1658	};
		1659
		1660	*AE::cv = sub (;&) {
		1661	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1662	};
		1663	};
		1664	die if $@;
		1665
		1666	&condvar
1253	}	1667	}
1254		1668
1255	# default implementation for ->signal	1669	# default implementation for ->signal
1256		1670
1257	our $HAVE_ASYNC_INTERRUPT;	1671	our $HAVE_ASYNC_INTERRUPT;
		1672
		1673	sub _have_async_interrupt() {
		1674	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1675	&& eval "use Async::Interrupt 1.02 (); 1")
		1676	unless defined $HAVE_ASYNC_INTERRUPT;
		1677
		1678	$HAVE_ASYNC_INTERRUPT
		1679	}
		1680
1258	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1681	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1259	our (%SIG_ASY, %SIG_ASY_W);	1682	our (%SIG_ASY, %SIG_ASY_W);
1260	our ($SIG_COUNT, $SIG_TW);	1683	our ($SIG_COUNT, $SIG_TW);
1261		1684
1262	sub _signal_exec {	1685	# install a dummy wakeup watcher to reduce signal catching latency
1263	$HAVE_ASYNC_INTERRUPT	1686	# used by Impls
1264	? $SIGPIPE_R->drain	1687	sub _sig_add() {
1265	: sysread $SIGPIPE_R, my $dummy, 9;	1688	unless ($SIG_COUNT++) {
		1689	# try to align timer on a full-second boundary, if possible
		1690	my $NOW = AE::now;
1266		1691
1267	while (%SIG_EV) {	1692	$SIG_TW = AE::timer
1268	for (keys %SIG_EV) {	1693	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
1269	delete $SIG_EV{$_};	1694	$MAX_SIGNAL_LATENCY,
1270	$_->() for values %{ $SIG_CB{$_} || {} };	1695	sub { } # just for the PERL_ASYNC_CHECK
1271	}	1696	;
1272	}	1697	}
1273	}	1698	}
1274		1699
1275	sub _signal {	1700	sub _sig_del {
1276	my (undef, %arg) = @_;
1277
1278	my $signal = uc $arg{signal}
1279	or Carp::croak "required option 'signal' is missing";
1280
1281	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1282
1283	if ($HAVE_ASYNC_INTERRUPT) {
1284	# async::interrupt
1285
1286	$SIG_ASY{$signal} ||= do {
1287	my $asy = new Async::Interrupt
1288	cb => sub { undef $SIG_EV{$signal} },
1289	signal => $signal,
1290	pipe => [$SIGPIPE_R->filenos],
1291	;
1292	$asy->pipe_autodrain (0);
1293
1294	$asy
1295	};
1296
1297	} else {
1298	# pure perl
1299
1300	$SIG{$signal} ||= sub {
1301	local $!;
1302	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1303	undef $SIG_EV{$signal};
1304	};
1305
1306	# can't do signal processing without introducing races in pure perl,
1307	# so limit the signal latency.
1308	++$SIG_COUNT;
1309	$SIG_TW ||= AnyEvent->timer (
1310	after => $MAX_SIGNAL_LATENCY,
1311	interval => $MAX_SIGNAL_LATENCY,
1312	cb => sub { }, # just for the PERL_ASYNC_CHECK
1313	);
1314	}
1315
1316	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1317	}
1318
1319	sub signal {
1320	# probe for availability of Async::Interrupt
1321	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
1322	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1323
1324	$HAVE_ASYNC_INTERRUPT = 1;
1325	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1326	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
1327
1328	} else {
1329	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
1330
1331	require Fcntl;
1332
1333	if (AnyEvent::WIN32) {
1334	require AnyEvent::Util;
1335
1336	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1337	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1338	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1339	} else {
1340	pipe $SIGPIPE_R, $SIGPIPE_W;
1341	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1342	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1343
1344	# not strictly required, as $^F is normally 2, but let's make sure...
1345	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1346	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1347	}
1348
1349	$SIGPIPE_R
1350	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1351
1352	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1353	}
1354
1355	*signal = \&_signal;
1356	&signal
1357	}
1358
1359	sub AnyEvent::Base::signal::DESTROY {
1360	my ($signal, $cb) = @{$_[0]};
1361
1362	undef $SIG_TW	1701	undef $SIG_TW
1363	unless --$SIG_COUNT;	1702	unless --$SIG_COUNT;
		1703	}
1364		1704
		1705	our $_sig_name_init; $_sig_name_init = sub {
		1706	eval q{ # poor man's autoloading {}
		1707	undef $_sig_name_init;
		1708
		1709	if (_have_async_interrupt) {
		1710	*sig2num = \&Async::Interrupt::sig2num;
		1711	*sig2name = \&Async::Interrupt::sig2name;
		1712	} else {
		1713	require Config;
		1714
		1715	my %signame2num;
		1716	@signame2num{ split ' ', $Config::Config{sig_name} }
		1717	= split ' ', $Config::Config{sig_num};
		1718
		1719	my @signum2name;
		1720	@signum2name[values %signame2num] = keys %signame2num;
		1721
		1722	*sig2num = sub($) {
		1723	$_[0] > 0 ? shift : $signame2num{+shift}
		1724	};
		1725	*sig2name = sub ($) {
		1726	$_[0] > 0 ? $signum2name[+shift] : shift
		1727	};
		1728	}
		1729	};
		1730	die if $@;
		1731	};
		1732
		1733	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1734	sub sig2name($) { &$_sig_name_init; &sig2name }
		1735
		1736	sub signal {
		1737	eval q{ # poor man's autoloading {}
		1738	# probe for availability of Async::Interrupt
		1739	if (_have_async_interrupt) {
		1740	AnyEvent::log 8 => "Using Async::Interrupt for race-free signal handling.";
		1741
		1742	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1743	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1744
		1745	} else {
		1746	AnyEvent::log 8 => "Using emulated perl signal handling with latency timer.";
		1747
		1748	if (AnyEvent::WIN32) {
		1749	require AnyEvent::Util;
		1750
		1751	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1752	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1753	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1754	} else {
		1755	pipe $SIGPIPE_R, $SIGPIPE_W;
		1756	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1757	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1758
		1759	# not strictly required, as $^F is normally 2, but let's make sure...
		1760	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1761	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1762	}
		1763
		1764	$SIGPIPE_R
		1765	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1766
		1767	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1768	}
		1769
		1770	*signal = $HAVE_ASYNC_INTERRUPT
		1771	? sub {
		1772	my (undef, %arg) = @_;
		1773
		1774	# async::interrupt
		1775	my $signal = sig2num $arg{signal};
		1776	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1777
		1778	$SIG_ASY{$signal} ||= new Async::Interrupt
		1779	cb => sub { undef $SIG_EV{$signal} },
		1780	signal => $signal,
		1781	pipe => [$SIGPIPE_R->filenos],
		1782	pipe_autodrain => 0,
		1783	;
		1784
		1785	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1786	}
		1787	: sub {
		1788	my (undef, %arg) = @_;
		1789
		1790	# pure perl
		1791	my $signal = sig2name $arg{signal};
		1792	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1793
		1794	$SIG{$signal} ||= sub {
		1795	local $!;
		1796	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1797	undef $SIG_EV{$signal};
		1798	};
		1799
		1800	# can't do signal processing without introducing races in pure perl,
		1801	# so limit the signal latency.
		1802	_sig_add;
		1803
		1804	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1805	}
		1806	;
		1807
		1808	*AnyEvent::Base::signal::DESTROY = sub {
		1809	my ($signal, $cb) = @{$_[0]};
		1810
		1811	_sig_del;
		1812
1365	delete $SIG_CB{$signal}{$cb};	1813	delete $SIG_CB{$signal}{$cb};
1366		1814
		1815	$HAVE_ASYNC_INTERRUPT
		1816	? delete $SIG_ASY{$signal}
1367	# delete doesn't work with older perls - they then	1817	: # delete doesn't work with older perls - they then
1368	# print weird messages, or just unconditionally exit	1818	# print weird messages, or just unconditionally exit
1369	# instead of getting the default action.	1819	# instead of getting the default action.
1370	undef $SIG{$signal}	1820	undef $SIG{$signal}
1371	unless keys %{ $SIG_CB{$signal} };	1821	unless keys %{ $SIG_CB{$signal} };
		1822	};
		1823
		1824	*_signal_exec = sub {
		1825	$HAVE_ASYNC_INTERRUPT
		1826	? $SIGPIPE_R->drain
		1827	: sysread $SIGPIPE_R, (my $dummy), 9;
		1828
		1829	while (%SIG_EV) {
		1830	for (keys %SIG_EV) {
		1831	delete $SIG_EV{$_};
		1832	&$_ for values %{ $SIG_CB{$_} || {} };
		1833	}
		1834	}
		1835	};
		1836	};
		1837	die if $@;
		1838
		1839	&signal
1372	}	1840	}
1373		1841
1374	# default implementation for ->child	1842	# default implementation for ->child
1375		1843
1376	our %PID_CB;	1844	our %PID_CB;
1377	our $CHLD_W;	1845	our $CHLD_W;
1378	our $CHLD_DELAY_W;	1846	our $CHLD_DELAY_W;
1379	our $WNOHANG;
1380		1847
1381	sub _sigchld {	1848	# used by many Impl's
1382	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1849	sub _emit_childstatus($$) {
1383	$_->($pid, $?)	1850	my (undef, $rpid, $rstatus) = @_;
		1851
		1852	$_->($rpid, $rstatus)
1384	for values %{ $PID_CB{$pid} || {} },	1853	for values %{ $PID_CB{$rpid} || {} },
1385	values %{ $PID_CB{0} || {} };	1854	values %{ $PID_CB{0} || {} };
1386	}
1387	}	1855	}
1388		1856
1389	sub child {	1857	sub child {
		1858	eval q{ # poor man's autoloading {}
		1859	*_sigchld = sub {
		1860	my $pid;
		1861
		1862	AnyEvent->_emit_childstatus ($pid, $?)
		1863	while ($pid = waitpid -1, WNOHANG) > 0;
		1864	};
		1865
		1866	*child = sub {
1390	my (undef, %arg) = @_;	1867	my (undef, %arg) = @_;
1391		1868
1392	defined (my $pid = $arg{pid} + 0)	1869	my $pid = $arg{pid};
1393	or Carp::croak "required option 'pid' is missing";	1870	my $cb = $arg{cb};
1394		1871
1395	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1872	$PID_CB{$pid}{$cb+0} = $cb;
1396		1873
1397	# WNOHANG is almost cetrainly 1 everywhere
1398	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
1399	? 1
1400	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1401
1402	unless ($CHLD_W) {	1874	unless ($CHLD_W) {
1403	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1875	$CHLD_W = AE::signal CHLD => \&_sigchld;
1404	# child could be a zombie already, so make at least one round	1876	# child could be a zombie already, so make at least one round
1405	&_sigchld;	1877	&_sigchld;
1406	}	1878	}
1407		1879
1408	bless [$pid, $arg{cb}], "AnyEvent::Base::child"	1880	bless [$pid, $cb+0], "AnyEvent::Base::child"
1409	}	1881	};
1410		1882
1411	sub AnyEvent::Base::child::DESTROY {	1883	*AnyEvent::Base::child::DESTROY = sub {
1412	my ($pid, $cb) = @{$_[0]};	1884	my ($pid, $icb) = @{$_[0]};
1413		1885
1414	delete $PID_CB{$pid}{$cb};	1886	delete $PID_CB{$pid}{$icb};
1415	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1887	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1416		1888
1417	undef $CHLD_W unless keys %PID_CB;	1889	undef $CHLD_W unless keys %PID_CB;
		1890	};
		1891	};
		1892	die if $@;
		1893
		1894	&child
1418	}	1895	}
1419		1896
1420	# idle emulation is done by simply using a timer, regardless	1897	# idle emulation is done by simply using a timer, regardless
1421	# of whether the process is idle or not, and not letting	1898	# of whether the process is idle or not, and not letting
1422	# the callback use more than 50% of the time.	1899	# the callback use more than 50% of the time.
1423	sub idle {	1900	sub idle {
		1901	eval q{ # poor man's autoloading {}
		1902	*idle = sub {
1424	my (undef, %arg) = @_;	1903	my (undef, %arg) = @_;
1425		1904
1426	my ($cb, $w, $rcb) = $arg{cb};	1905	my ($cb, $w, $rcb) = $arg{cb};
1427		1906
1428	$rcb = sub {	1907	$rcb = sub {
1429	if ($cb) {	1908	if ($cb) {
1430	$w = _time;	1909	$w = AE::time;
1431	&$cb;	1910	&$cb;
1432	$w = _time - $w;	1911	$w = AE::time - $w;
1433		1912
1434	# never use more then 50% of the time for the idle watcher,	1913	# never use more then 50% of the time for the idle watcher,
1435	# within some limits	1914	# within some limits
1436	$w = 0.0001 if $w < 0.0001;	1915	$w = 0.0001 if $w < 0.0001;
1437	$w = 5 if $w > 5;	1916	$w = 5 if $w > 5;
1438		1917
1439	$w = AnyEvent->timer (after => $w, cb => $rcb);	1918	$w = AE::timer $w, 0, $rcb;
1440	} else {	1919	} else {
1441	# clean up...	1920	# clean up...
1442	undef $w;	1921	undef $w;
1443	undef $rcb;	1922	undef $rcb;
		1923	}
		1924	};
		1925
		1926	$w = AE::timer 0.05, 0, $rcb;
		1927
		1928	bless \\$cb, "AnyEvent::Base::idle"
1444	}	1929	};
		1930
		1931	*AnyEvent::Base::idle::DESTROY = sub {
		1932	undef $${$_[0]};
		1933	};
1445	};	1934	};
		1935	die if $@;
1446		1936
1447	$w = AnyEvent->timer (after => 0.05, cb => $rcb);	1937	&idle
1448
1449	bless \\$cb, "AnyEvent::Base::idle"
1450	}
1451
1452	sub AnyEvent::Base::idle::DESTROY {
1453	undef $${$_[0]};
1454	}	1938	}
1455		1939
1456	package AnyEvent::CondVar;	1940	package AnyEvent::CondVar;
1457		1941
1458	our @ISA = AnyEvent::CondVar::Base::;	1942	our @ISA = AnyEvent::CondVar::Base::;
		1943
		1944	# only to be used for subclassing
		1945	sub new {
		1946	my $class = shift;
		1947	bless AnyEvent->condvar (@_), $class
		1948	}
1459		1949
1460	package AnyEvent::CondVar::Base;	1950	package AnyEvent::CondVar::Base;
1461		1951
1462	#use overload	1952	#use overload
1463	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1953	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
…		…
1473		1963
1474	sub _send {	1964	sub _send {
1475	# nop	1965	# nop
1476	}	1966	}
1477		1967
		1968	sub _wait {
		1969	AnyEvent->_poll until $_[0]{_ae_sent};
		1970	}
		1971
1478	sub send {	1972	sub send {
1479	my $cv = shift;	1973	my $cv = shift;
1480	$cv->{_ae_sent} = [@_];	1974	$cv->{_ae_sent} = [@_];
1481	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};	1975	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
1482	$cv->_send;	1976	$cv->_send;
…		…
1489		1983
1490	sub ready {	1984	sub ready {
1491	$_[0]{_ae_sent}	1985	$_[0]{_ae_sent}
1492	}	1986	}
1493		1987
1494	sub _wait {
1495	$WAITING
1496	and !$_[0]{_ae_sent}
1497	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
1498
1499	local $WAITING = 1;
1500	AnyEvent->one_event while !$_[0]{_ae_sent};
1501	}
1502
1503	sub recv {	1988	sub recv {
		1989	unless ($_[0]{_ae_sent}) {
		1990	$WAITING
		1991	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1992
		1993	local $WAITING = 1;
1504	$_[0]->_wait;	1994	$_[0]->_wait;
		1995	}
1505		1996
1506	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1997	$_[0]{_ae_croak}
1507	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1998	and Carp::croak $_[0]{_ae_croak};
		1999
		2000	wantarray
		2001	? @{ $_[0]{_ae_sent} }
		2002	: $_[0]{_ae_sent}[0]
1508	}	2003	}
1509		2004
1510	sub cb {	2005	sub cb {
1511	$_[0]{_ae_cb} = $_[1] if @_ > 1;	2006	my $cv = shift;
		2007
		2008	@_
		2009	and $cv->{_ae_cb} = shift
		2010	and $cv->{_ae_sent}
		2011	and (delete $cv->{_ae_cb})->($cv);
		2012
1512	$_[0]{_ae_cb}	2013	$cv->{_ae_cb}
1513	}	2014	}
1514		2015
1515	sub begin {	2016	sub begin {
1516	++$_[0]{_ae_counter};	2017	++$_[0]{_ae_counter};
1517	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	2018	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1522	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	2023	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1523	}	2024	}
1524		2025
1525	# undocumented/compatibility with pre-3.4	2026	# undocumented/compatibility with pre-3.4
1526	*broadcast = \&send;	2027	*broadcast = \&send;
1527	*wait = \&_wait;	2028	*wait = \&recv;
1528		2029
1529	=head1 ERROR AND EXCEPTION HANDLING	2030	=head1 ERROR AND EXCEPTION HANDLING
1530		2031
1531	In general, AnyEvent does not do any error handling - it relies on the	2032	In general, AnyEvent does not do any error handling - it relies on the
1532	caller to do that if required. The L<AnyEvent::Strict> module (see also	2033	caller to do that if required. The L<AnyEvent::Strict> module (see also
…		…
1544	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and	2045	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
1545	so on.	2046	so on.
1546		2047
1547	=head1 ENVIRONMENT VARIABLES	2048	=head1 ENVIRONMENT VARIABLES
1548		2049
1549	The following environment variables are used by this module or its	2050	AnyEvent supports a number of environment variables that tune the
1550	submodules.	2051	runtime behaviour. They are usually evaluated when AnyEvent is
		2052	loaded, initialised, or a submodule that uses them is loaded. Many of
		2053	them also cause AnyEvent to load additional modules - for example,
		2054	C<PERL_ANYEVENT_DEBUG_WRAP> causes the L<AnyEvent::Debug> module to be
		2055	loaded.
1551		2056
1552	Note that AnyEvent will remove I<all> environment variables starting with	2057	All the environment variables documented here start with
1553	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is	2058	C<PERL_ANYEVENT_>, which is what AnyEvent considers its own
1554	enabled.	2059	namespace. Other modules are encouraged (but by no means required) to use
		2060	C<PERL_ANYEVENT_SUBMODULE> if they have registered the AnyEvent::Submodule
		2061	namespace on CPAN, for any submodule. For example, L<AnyEvent::HTTP> could
		2062	be expected to use C<PERL_ANYEVENT_HTTP_PROXY> (it should not access env
		2063	variables starting with C<AE_>, see below).
		2064
		2065	All variables can also be set via the C<AE_> prefix, that is, instead
		2066	of setting C<PERL_ANYEVENT_VERBOSE> you can also set C<AE_VERBOSE>. In
		2067	case there is a clash btween anyevent and another program that uses
		2068	C<AE_something> you can set the corresponding C<PERL_ANYEVENT_something>
		2069	variable to the empty string, as those variables take precedence.
		2070
		2071	When AnyEvent is first loaded, it copies all C<AE_xxx> env variables
		2072	to their C<PERL_ANYEVENT_xxx> counterpart unless that variable already
		2073	exists. If taint mode is on, then AnyEvent will remove I<all> environment
		2074	variables starting with C<PERL_ANYEVENT_> from C<%ENV> (or replace them
		2075	with C<undef> or the empty string, if the corresaponding C<AE_> variable
		2076	is set).
		2077
		2078	The exact algorithm is currently:
		2079
		2080	1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
		2081	2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
		2082	3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
		2083
		2084	This ensures that child processes will not see the C<AE_> variables.
		2085
		2086	The following environment variables are currently known to AnyEvent:
1555		2087
1556	=over 4	2088	=over 4
1557		2089
1558	=item C<PERL_ANYEVENT_VERBOSE>	2090	=item C<PERL_ANYEVENT_VERBOSE>
1559		2091
1560	By default, AnyEvent will be completely silent except in fatal	2092	By default, AnyEvent will log messages with loglevel C<4> (C<error>) or
1561	conditions. You can set this environment variable to make AnyEvent more	2093	higher (see L<AnyEvent::Log>). You can set this environment variable to a
1562	talkative.	2094	numerical loglevel to make AnyEvent more (or less) talkative.
1563		2095
		2096	If you want to do more than just set the global logging level
		2097	you should have a look at C<PERL_ANYEVENT_LOG>, which allows much more
		2098	complex specifications.
		2099
		2100	When set to C<0> (C<off>), then no messages whatsoever will be logged with
		2101	everything else at defaults.
		2102
1564	When set to C<1> or higher, causes AnyEvent to warn about unexpected	2103	When set to C<5> or higher (C<warn>), AnyEvent warns about unexpected
1565	conditions, such as not being able to load the event model specified by	2104	conditions, such as not being able to load the event model specified by
1566	C<PERL_ANYEVENT_MODEL>.	2105	C<PERL_ANYEVENT_MODEL>, or a guard callback throwing an exception - this
		2106	is the minimum recommended level for use during development.
1567		2107
1568	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	2108	When set to C<7> or higher (info), AnyEvent reports which event model it
1569	model it chooses.	2109	chooses.
1570		2110
1571	When set to C<8> or higher, then AnyEvent will report extra information on	2111	When set to C<8> or higher (debug), then AnyEvent will report extra
1572	which optional modules it loads and how it implements certain features.	2112	information on which optional modules it loads and how it implements
		2113	certain features.
		2114
		2115	=item C<PERL_ANYEVENT_LOG>
		2116
		2117	Accepts rather complex logging specifications. For example, you could log
		2118	all C<debug> messages of some module to stderr, warnings and above to
		2119	stderr, and errors and above to syslog, with:
		2120
		2121	PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
		2122
		2123	For the rather extensive details, see L<AnyEvent::Log>.
		2124
		2125	This variable is evaluated when AnyEvent (or L<AnyEvent::Log>) is loaded,
		2126	so will take effect even before AnyEvent has initialised itself.
		2127
		2128	Note that specifying this environment variable causes the L<AnyEvent::Log>
		2129	module to be loaded, while C<PERL_ANYEVENT_VERBOSE> does not, so only
		2130	using the latter saves a few hundred kB of memory unless a module
		2131	explicitly needs the extra features of AnyEvent::Log.
1573		2132
1574	=item C<PERL_ANYEVENT_STRICT>	2133	=item C<PERL_ANYEVENT_STRICT>
1575		2134
1576	AnyEvent does not do much argument checking by default, as thorough	2135	AnyEvent does not do much argument checking by default, as thorough
1577	argument checking is very costly. Setting this variable to a true value	2136	argument checking is very costly. Setting this variable to a true value
…		…
1579	check the arguments passed to most method calls. If it finds any problems,	2138	check the arguments passed to most method calls. If it finds any problems,
1580	it will croak.	2139	it will croak.
1581		2140
1582	In other words, enables "strict" mode.	2141	In other words, enables "strict" mode.
1583		2142
1584	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>	2143	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1585	>>, it is definitely recommended to keep it off in production. Keeping	2144	>>, it is definitely recommended to keep it off in production. Keeping
1586	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs	2145	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
1587	can be very useful, however.	2146	can be very useful, however.
1588		2147
		2148	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		2149
		2150	If this env variable is nonempty, then its contents will be interpreted by
		2151	C<AnyEvent::Socket::parse_hostport> and C<AnyEvent::Debug::shell> (after
		2152	replacing every occurance of C<$$> by the process pid). The shell object
		2153	is saved in C<$AnyEvent::Debug::SHELL>.
		2154
		2155	This happens when the first watcher is created.
		2156
		2157	For example, to bind a debug shell on a unix domain socket in
		2158	F<< /tmp/debug<pid>.sock >>, you could use this:
		2159
		2160	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		2161	# connect with e.g.: socat readline /tmp/debug123.sock
		2162
		2163	Or to bind to tcp port 4545 on localhost:
		2164
		2165	PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
		2166	# connect with e.g.: telnet localhost 4545
		2167
		2168	Note that creating sockets in F</tmp> or on localhost is very unsafe on
		2169	multiuser systems.
		2170
		2171	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2172
		2173	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2174	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
		2175
1589	=item C<PERL_ANYEVENT_MODEL>	2176	=item C<PERL_ANYEVENT_MODEL>
1590		2177
1591	This can be used to specify the event model to be used by AnyEvent, before	2178	This can be used to specify the event model to be used by AnyEvent, before
1592	auto detection and -probing kicks in. It must be a string consisting	2179	auto detection and -probing kicks in.
1593	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	2180
		2181	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2182	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
1594	and the resulting module name is loaded and if the load was successful,	2183	resulting module name is loaded and - if the load was successful - used as
1595	used as event model. If it fails to load AnyEvent will proceed with	2184	event model backend. If it fails to load then AnyEvent will proceed with
1596	auto detection and -probing.	2185	auto detection and -probing.
1597		2186
1598	This functionality might change in future versions.	2187	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2188	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2189	the end of a string designates a module name and quotes it appropriately).
1599		2190
1600	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	2191	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1601	could start your program like this:	2192	could start your program like this:
1602		2193
1603	PERL_ANYEVENT_MODEL=Perl perl ...	2194	PERL_ANYEVENT_MODEL=Perl perl ...
		2195
		2196	=item C<PERL_ANYEVENT_IO_MODEL>
		2197
		2198	The current file I/O model - see L<AnyEvent::IO> for more info.
		2199
		2200	At the moment, only C<Perl> (small, pure-perl, synchronous) and
		2201	C<IOAIO> (truly asynchronous) are supported. The default is C<IOAIO> if
		2202	L<AnyEvent::AIO> can be loaded, otherwise it is C<Perl>.
1604		2203
1605	=item C<PERL_ANYEVENT_PROTOCOLS>	2204	=item C<PERL_ANYEVENT_PROTOCOLS>
1606		2205
1607	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences	2206	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1608	for IPv4 or IPv6. The default is unspecified (and might change, or be the result	2207	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
…		…
1613	used, and preference will be given to protocols mentioned earlier in the	2212	used, and preference will be given to protocols mentioned earlier in the
1614	list.	2213	list.
1615		2214
1616	This variable can effectively be used for denial-of-service attacks	2215	This variable can effectively be used for denial-of-service attacks
1617	against local programs (e.g. when setuid), although the impact is likely	2216	against local programs (e.g. when setuid), although the impact is likely
1618	small, as the program has to handle conenction and other failures anyways.	2217	small, as the program has to handle connection and other failures anyways.
1619		2218
1620	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,	2219	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1621	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>	2220	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1622	- only support IPv4, never try to resolve or contact IPv6	2221	- only support IPv4, never try to resolve or contact IPv6
1623	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or	2222	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1624	IPv6, but prefer IPv6 over IPv4.	2223	IPv6, but prefer IPv6 over IPv4.
1625		2224
		2225	=item C<PERL_ANYEVENT_HOSTS>
		2226
		2227	This variable, if specified, overrides the F</etc/hosts> file used by
		2228	L<AnyEvent::Socket>C<::resolve_sockaddr>, i.e. hosts aliases will be read
		2229	from that file instead.
		2230
1626	=item C<PERL_ANYEVENT_EDNS0>	2231	=item C<PERL_ANYEVENT_EDNS0>
1627		2232
1628	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension	2233	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension for
1629	for DNS. This extension is generally useful to reduce DNS traffic, but	2234	DNS. This extension is generally useful to reduce DNS traffic, especially
1630	some (broken) firewalls drop such DNS packets, which is why it is off by	2235	when DNSSEC is involved, but some (broken) firewalls drop such DNS
1631	default.	2236	packets, which is why it is off by default.
1632		2237
1633	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce	2238	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1634	EDNS0 in its DNS requests.	2239	EDNS0 in its DNS requests.
1635		2240
1636	=item C<PERL_ANYEVENT_MAX_FORKS>	2241	=item C<PERL_ANYEVENT_MAX_FORKS>
…		…
1642		2247
1643	The default value for the C<max_outstanding> parameter for the default DNS	2248	The default value for the C<max_outstanding> parameter for the default DNS
1644	resolver - this is the maximum number of parallel DNS requests that are	2249	resolver - this is the maximum number of parallel DNS requests that are
1645	sent to the DNS server.	2250	sent to the DNS server.
1646		2251
		2252	=item C<PERL_ANYEVENT_MAX_SIGNAL_LATENCY>
		2253
		2254	Perl has inherently racy signal handling (you can basically choose between
		2255	losing signals and memory corruption) - pure perl event loops (including
		2256	C<AnyEvent::Loop>, when C<Async::Interrupt> isn't available) therefore
		2257	have to poll regularly to avoid losing signals.
		2258
		2259	Some event loops are racy, but don't poll regularly, and some event loops
		2260	are written in C but are still racy. For those event loops, AnyEvent
		2261	installs a timer that regularly wakes up the event loop.
		2262
		2263	By default, the interval for this timer is C<10> seconds, but you can
		2264	override this delay with this environment variable (or by setting
		2265	the C<$AnyEvent::MAX_SIGNAL_LATENCY> variable before creating signal
		2266	watchers).
		2267
		2268	Lower values increase CPU (and energy) usage, higher values can introduce
		2269	long delays when reaping children or waiting for signals.
		2270
		2271	The L<AnyEvent::Async> module, if available, will be used to avoid this
		2272	polling (with most event loops).
		2273
1647	=item C<PERL_ANYEVENT_RESOLV_CONF>	2274	=item C<PERL_ANYEVENT_RESOLV_CONF>
1648		2275
1649	The file to use instead of F</etc/resolv.conf> (or OS-specific	2276	The absolute path to a F<resolv.conf>-style file to use instead of
1650	configuration) in the default resolver. When set to the empty string, no	2277	F</etc/resolv.conf> (or the OS-specific configuration) in the default
1651	default config will be used.	2278	resolver, or the empty string to select the default configuration.
1652		2279
1653	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.	2280	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
1654		2281
1655	When neither C<ca_file> nor C<ca_path> was specified during	2282	When neither C<ca_file> nor C<ca_path> was specified during
1656	L<AnyEvent::TLS> context creation, and either of these environment	2283	L<AnyEvent::TLS> context creation, and either of these environment
1657	variables exist, they will be used to specify CA certificate locations	2284	variables are nonempty, they will be used to specify CA certificate
1658	instead of a system-dependent default.	2285	locations instead of a system-dependent default.
1659		2286
1660	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>	2287	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
1661		2288
1662	When these are set to C<1>, then the respective modules are not	2289	When these are set to C<1>, then the respective modules are not
1663	loaded. Mostly good for testing AnyEvent itself.	2290	loaded. Mostly good for testing AnyEvent itself.
…		…
1726	warn "read: $input\n"; # output what has been read	2353	warn "read: $input\n"; # output what has been read
1727	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2354	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1728	},	2355	},
1729	);	2356	);
1730		2357
1731	my $time_watcher; # can only be used once
1732
1733	sub new_timer {
1734	$timer = AnyEvent->timer (after => 1, cb => sub {	2358	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1735	warn "timeout\n"; # print 'timeout' about every second	2359	warn "timeout\n"; # print 'timeout' at most every second
1736	&new_timer; # and restart the time
1737	});	2360	});
1738	}
1739
1740	new_timer; # create first timer
1741		2361
1742	$cv->recv; # wait until user enters /^q/i	2362	$cv->recv; # wait until user enters /^q/i
1743		2363
1744	=head1 REAL-WORLD EXAMPLE	2364	=head1 REAL-WORLD EXAMPLE
1745		2365
…		…
1818		2438
1819	The actual code goes further and collects all errors (C<die>s, exceptions)	2439	The actual code goes further and collects all errors (C<die>s, exceptions)
1820	that occurred during request processing. The C<result> method detects	2440	that occurred during request processing. The C<result> method detects
1821	whether an exception as thrown (it is stored inside the $txn object)	2441	whether an exception as thrown (it is stored inside the $txn object)
1822	and just throws the exception, which means connection errors and other	2442	and just throws the exception, which means connection errors and other
1823	problems get reported tot he code that tries to use the result, not in a	2443	problems get reported to the code that tries to use the result, not in a
1824	random callback.	2444	random callback.
1825		2445
1826	All of this enables the following usage styles:	2446	All of this enables the following usage styles:
1827		2447
1828	1. Blocking:	2448	1. Blocking:
…		…
1876	through AnyEvent. The benchmark creates a lot of timers (with a zero	2496	through AnyEvent. The benchmark creates a lot of timers (with a zero
1877	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2497	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1878	which it is), lets them fire exactly once and destroys them again.	2498	which it is), lets them fire exactly once and destroys them again.
1879		2499
1880	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2500	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1881	distribution.	2501	distribution. It uses the L<AE> interface, which makes a real difference
		2502	for the EV and Perl backends only.
1882		2503
1883	=head3 Explanation of the columns	2504	=head3 Explanation of the columns
1884		2505
1885	I<watcher> is the number of event watchers created/destroyed. Since	2506	I<watcher> is the number of event watchers created/destroyed. Since
1886	different event models feature vastly different performances, each event	2507	different event models feature vastly different performances, each event
…		…
1907	watcher.	2528	watcher.
1908		2529
1909	=head3 Results	2530	=head3 Results
1910		2531
1911	name watchers bytes create invoke destroy comment	2532	name watchers bytes create invoke destroy comment
1912	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2533	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1913	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2534	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1914	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2535	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1915	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2536	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1916	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2537	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1917	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2538	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1918	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll	2539	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1919	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll	2540	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1920	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2541	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1921	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2542	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1922	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2543	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1923	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2544	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1924		2545
1925	=head3 Discussion	2546	=head3 Discussion
1926		2547
1927	The benchmark does I<not> measure scalability of the event loop very	2548	The benchmark does I<not> measure scalability of the event loop very
1928	well. For example, a select-based event loop (such as the pure perl one)	2549	well. For example, a select-based event loop (such as the pure perl one)
…		…
1940	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2561	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1941	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2562	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1942	cycles with POE.	2563	cycles with POE.
1943		2564
1944	C<EV> is the sole leader regarding speed and memory use, which are both	2565	C<EV> is the sole leader regarding speed and memory use, which are both
1945	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2566	maximal/minimal, respectively. When using the L<AE> API there is zero
		2567	overhead (when going through the AnyEvent API create is about 5-6 times
		2568	slower, with other times being equal, so still uses far less memory than
1946	far less memory than any other event loop and is still faster than Event	2569	any other event loop and is still faster than Event natively).
1947	natively.
1948		2570
1949	The pure perl implementation is hit in a few sweet spots (both the	2571	The pure perl implementation is hit in a few sweet spots (both the
1950	constant timeout and the use of a single fd hit optimisations in the perl	2572	constant timeout and the use of a single fd hit optimisations in the perl
1951	interpreter and the backend itself). Nevertheless this shows that it	2573	interpreter and the backend itself). Nevertheless this shows that it
1952	adds very little overhead in itself. Like any select-based backend its	2574	adds very little overhead in itself. Like any select-based backend its
…		…
2000	(even when used without AnyEvent), but most event loops have acceptable	2622	(even when used without AnyEvent), but most event loops have acceptable
2001	performance with or without AnyEvent.	2623	performance with or without AnyEvent.
2002		2624
2003	=item * The overhead AnyEvent adds is usually much smaller than the overhead of	2625	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
2004	the actual event loop, only with extremely fast event loops such as EV	2626	the actual event loop, only with extremely fast event loops such as EV
2005	adds AnyEvent significant overhead.	2627	does AnyEvent add significant overhead.
2006		2628
2007	=item * You should avoid POE like the plague if you want performance or	2629	=item * You should avoid POE like the plague if you want performance or
2008	reasonable memory usage.	2630	reasonable memory usage.
2009		2631
2010	=back	2632	=back
…		…
2026	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2648	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
2027	(1%) are active. This mirrors the activity of large servers with many	2649	(1%) are active. This mirrors the activity of large servers with many
2028	connections, most of which are idle at any one point in time.	2650	connections, most of which are idle at any one point in time.
2029		2651
2030	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2652	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
2031	distribution.	2653	distribution. It uses the L<AE> interface, which makes a real difference
		2654	for the EV and Perl backends only.
2032		2655
2033	=head3 Explanation of the columns	2656	=head3 Explanation of the columns
2034		2657
2035	I<sockets> is the number of sockets, and twice the number of "servers" (as	2658	I<sockets> is the number of sockets, and twice the number of "servers" (as
2036	each server has a read and write socket end).	2659	each server has a read and write socket end).
…		…
2044	a new one that moves the timeout into the future.	2667	a new one that moves the timeout into the future.
2045		2668
2046	=head3 Results	2669	=head3 Results
2047		2670
2048	name sockets create request	2671	name sockets create request
2049	EV 20000 69.01 11.16	2672	EV 20000 62.66 7.99
2050	Perl 20000 73.32 35.87	2673	Perl 20000 68.32 32.64
2051	IOAsync 20000 157.00 98.14 epoll	2674	IOAsync 20000 174.06 101.15 epoll
2052	IOAsync 20000 159.31 616.06 poll	2675	IOAsync 20000 174.67 610.84 poll
2053	Event 20000 212.62 257.32	2676	Event 20000 202.69 242.91
2054	Glib 20000 651.16 1896.30	2677	Glib 20000 557.01 1689.52
2055	POE 20000 349.67 12317.24 uses POE::Loop::Event	2678	POE 20000 341.54 12086.32 uses POE::Loop::Event
2056		2679
2057	=head3 Discussion	2680	=head3 Discussion
2058		2681
2059	This benchmark I<does> measure scalability and overall performance of the	2682	This benchmark I<does> measure scalability and overall performance of the
2060	particular event loop.	2683	particular event loop.
…		…
2186	As you can see, the AnyEvent + EV combination even beats the	2809	As you can see, the AnyEvent + EV combination even beats the
2187	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl	2810	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2188	backend easily beats IO::Lambda and POE.	2811	backend easily beats IO::Lambda and POE.
2189		2812
2190	And even the 100% non-blocking version written using the high-level (and	2813	And even the 100% non-blocking version written using the high-level (and
2191	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a	2814	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
2192	large margin, even though it does all of DNS, tcp-connect and socket I/O	2815	higher level ("unoptimised") abstractions by a large margin, even though
2193	in a non-blocking way.	2816	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
2194		2817
2195	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and	2818	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2196	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are	2819	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2197	part of the IO::lambda distribution and were used without any changes.	2820	part of the IO::Lambda distribution and were used without any changes.
2198		2821
2199		2822
2200	=head1 SIGNALS	2823	=head1 SIGNALS
2201		2824
2202	AnyEvent currently installs handlers for these signals:	2825	AnyEvent currently installs handlers for these signals:
…		…
2239	unless defined $SIG{PIPE};	2862	unless defined $SIG{PIPE};
2240		2863
2241	=head1 RECOMMENDED/OPTIONAL MODULES	2864	=head1 RECOMMENDED/OPTIONAL MODULES
2242		2865
2243	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and	2866	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
2244	it's built-in modules) are required to use it.	2867	its built-in modules) are required to use it.
2245		2868
2246	That does not mean that AnyEvent won't take advantage of some additional	2869	That does not mean that AnyEvent won't take advantage of some additional
2247	modules if they are installed.	2870	modules if they are installed.
2248		2871
2249	This section epxlains which additional modules will be used, and how they	2872	This section explains which additional modules will be used, and how they
2250	affect AnyEvent's operetion.	2873	affect AnyEvent's operation.
2251		2874
2252	=over 4	2875	=over 4
2253		2876
2254	=item L<Async::Interrupt>	2877	=item L<Async::Interrupt>
2255		2878
2256	This slightly arcane module is used to implement fast signal handling: To	2879	This slightly arcane module is used to implement fast signal handling: To
2257	my knowledge, there is no way to do completely race-free and quick	2880	my knowledge, there is no way to do completely race-free and quick
2258	signal handling in pure perl. To ensure that signals still get	2881	signal handling in pure perl. To ensure that signals still get
2259	delivered, AnyEvent will start an interval timer to wake up perl (and	2882	delivered, AnyEvent will start an interval timer to wake up perl (and
2260	catch the signals) with soemd elay (default is 10 seconds, look for	2883	catch the signals) with some delay (default is 10 seconds, look for
2261	C<$AnyEvent::MAX_SIGNAL_LATENCY>).	2884	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
2262		2885
2263	If this module is available, then it will be used to implement signal	2886	If this module is available, then it will be used to implement signal
2264	catching, which means that signals will not be delayed, and the event loop	2887	catching, which means that signals will not be delayed, and the event loop
2265	will not be interrupted regularly, which is more efficient (And good for	2888	will not be interrupted regularly, which is more efficient (and good for
2266	battery life on laptops).	2889	battery life on laptops).
2267		2890
2268	This affects not just the pure-perl event loop, but also other event loops	2891	This affects not just the pure-perl event loop, but also other event loops
2269	that have no signal handling on their own (e.g. Glib, Tk, Qt).	2892	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2893
		2894	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2895	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2896	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2897	does nothing for those backends.
2270		2898
2271	=item L<EV>	2899	=item L<EV>
2272		2900
2273	This module isn't really "optional", as it is simply one of the backend	2901	This module isn't really "optional", as it is simply one of the backend
2274	event loops that AnyEvent can use. However, it is simply the best event	2902	event loops that AnyEvent can use. However, it is simply the best event
…		…
2277	automatic timer adjustments even when no monotonic clock is available,	2905	automatic timer adjustments even when no monotonic clock is available,
2278	can take avdantage of advanced kernel interfaces such as C<epoll> and	2906	can take avdantage of advanced kernel interfaces such as C<epoll> and
2279	C<kqueue>, and is the fastest backend I<by far>. You can even embed	2907	C<kqueue>, and is the fastest backend I<by far>. You can even embed
2280	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).	2908	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
2281		2909
		2910	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2911	then this module will do nothing for you.
		2912
2282	=item L<Guard>	2913	=item L<Guard>
2283		2914
2284	The guard module, when used, will be used to implement	2915	The guard module, when used, will be used to implement
2285	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a	2916	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
2286	lot less memory), but otherwise doesn't affect guard operation much. It is	2917	lot less memory), but otherwise doesn't affect guard operation much. It is
2287	purely used for performance.	2918	purely used for performance.
2288		2919
2289	=item L<JSON> and L<JSON::XS>	2920	=item L<JSON> and L<JSON::XS>
2290		2921
2291	This module is required when you want to read or write JSON data via	2922	One of these modules is required when you want to read or write JSON data
2292	L<AnyEvent::Handle>. It is also written in pure-perl, but can take	2923	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
2293	advantage of the ulta-high-speed L<JSON::XS> module when it is installed.	2924	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
2294
2295	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
2296	installed.
2297		2925
2298	=item L<Net::SSLeay>	2926	=item L<Net::SSLeay>
2299		2927
2300	Implementing TLS/SSL in Perl is certainly interesting, but not very	2928	Implementing TLS/SSL in Perl is certainly interesting, but not very
2301	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with	2929	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
2302	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.	2930	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
2303		2931
2304	=item L<Time::HiRes>	2932	=item L<Time::HiRes>
2305		2933
2306	This module is part of perl since release 5.008. It will be used when the	2934	This module is part of perl since release 5.008. It will be used when the
2307	chosen event library does not come with a timing source on it's own. The	2935	chosen event library does not come with a timing source of its own. The
2308	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to	2936	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
2309	try to use a monotonic clock for timing stability.	2937	try to use a monotonic clock for timing stability.
2310		2938
		2939	=item L<AnyEvent::AIO> (and L<IO::AIO>)
		2940
		2941	The default implementation of L<AnyEvent::IO> is to do I/O synchronously,
		2942	stopping programs while they access the disk, which is fine for a lot of
		2943	programs.
		2944
		2945	Installing AnyEvent::AIO (and its IO::AIO dependency) makes it switch to
		2946	a true asynchronous implementation, so event processing can continue even
		2947	while waiting for disk I/O.
		2948
2311	=back	2949	=back
2312		2950
2313		2951
2314	=head1 FORK	2952	=head1 FORK
2315		2953
2316	Most event libraries are not fork-safe. The ones who are usually are	2954	Most event libraries are not fork-safe. The ones who are usually are
2317	because they rely on inefficient but fork-safe C<select> or C<poll>	2955	because they rely on inefficient but fork-safe C<select> or C<poll> calls
2318	calls. Only L<EV> is fully fork-aware.	2956	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2957	are usually badly thought-out hacks that are incompatible with fork in
		2958	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2959	continue event-processing in both parent and child (or both, if you know
		2960	what you are doing).
		2961
		2962	This means that, in general, you cannot fork and do event processing in
		2963	the child if the event library was initialised before the fork (which
		2964	usually happens when the first AnyEvent watcher is created, or the library
		2965	is loaded).
2319		2966
2320	If you have to fork, you must either do so I<before> creating your first	2967	If you have to fork, you must either do so I<before> creating your first
2321	watcher OR you must not use AnyEvent at all in the child OR you must do	2968	watcher OR you must not use AnyEvent at all in the child OR you must do
2322	something completely out of the scope of AnyEvent.	2969	something completely out of the scope of AnyEvent (see below).
		2970
		2971	The problem of doing event processing in the parent I<and> the child
		2972	is much more complicated: even for backends that I<are> fork-aware or
		2973	fork-safe, their behaviour is not usually what you want: fork clones all
		2974	watchers, that means all timers, I/O watchers etc. are active in both
		2975	parent and child, which is almost never what you want. Using C<exec>
		2976	to start worker children from some kind of manage prrocess is usually
		2977	preferred, because it is much easier and cleaner, at the expense of having
		2978	to have another binary.
		2979
		2980	In addition to logical problems with fork, there are also implementation
		2981	problems. For example, on POSIX systems, you cannot fork at all in Perl
		2982	code if a thread (I am talking of pthreads here) was ever created in the
		2983	process, and this is just the tip of the iceberg. In general, using fork
		2984	from Perl is difficult, and attempting to use fork without an exec to
		2985	implement some kind of parallel processing is almost certainly doomed.
		2986
		2987	To safely fork and exec, you should use a module such as
		2988	L<Proc::FastSpawn> that let's you safely fork and exec new processes.
		2989
		2990	If you want to do multiprocessing using processes, you can
		2991	look at the L<AnyEvent::Fork> module (and some related modules
		2992	such as L<AnyEvent::Fork::RPC>, L<AnyEvent::Fork::Pool> and
		2993	L<AnyEvent::Fork::Remote>). This module allows you to safely create
		2994	subprocesses without any limitations - you can use X11 toolkits or
		2995	AnyEvent in the children created by L<AnyEvent::Fork> safely and without
		2996	any special precautions.
2323		2997
2324		2998
2325	=head1 SECURITY CONSIDERATIONS	2999	=head1 SECURITY CONSIDERATIONS
2326		3000
2327	AnyEvent can be forced to load any event model via	3001	AnyEvent can be forced to load any event model via
…		…
2357	pronounced).	3031	pronounced).
2358		3032
2359		3033
2360	=head1 SEE ALSO	3034	=head1 SEE ALSO
2361		3035
2362	Utility functions: L<AnyEvent::Util>.	3036	Tutorial/Introduction: L<AnyEvent::Intro>.
2363		3037
2364	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	3038	FAQ: L<AnyEvent::FAQ>.
2365	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	3039
		3040	Utility functions: L<AnyEvent::Util> (misc. grab-bag), L<AnyEvent::Log>
		3041	(simply logging).
		3042
		3043	Development/Debugging: L<AnyEvent::Strict> (stricter checking),
		3044	L<AnyEvent::Debug> (interactive shell, watcher tracing).
		3045
		3046	Supported event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>,
		3047	L<Glib::EV>, L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>,
		3048	L<Qt>, L<POE>, L<FLTK>.
2366		3049
2367	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	3050	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2368	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	3051	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2369	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	3052	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2370	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.	3053	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>,
		3054	L<AnyEvent::Impl::FLTK>.
2371		3055
2372	Non-blocking file handles, sockets, TCP clients and	3056	Non-blocking handles, pipes, stream sockets, TCP clients and
2373	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.	3057	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2374		3058
		3059	Asynchronous File I/O: L<AnyEvent::IO>.
		3060
2375	Asynchronous DNS: L<AnyEvent::DNS>.	3061	Asynchronous DNS: L<AnyEvent::DNS>.
2376		3062
2377	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,	3063	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
2378	L<Coro::Event>,
2379		3064
2380	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,	3065	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
2381	L<AnyEvent::HTTP>.	3066	L<AnyEvent::HTTP>.
2382		3067
2383		3068
2384	=head1 AUTHOR	3069	=head1 AUTHOR
2385		3070
2386	Marc Lehmann <schmorp@schmorp.de>	3071	Marc Lehmann <schmorp@schmorp.de>
2387	http://home.schmorp.de/	3072	http://anyevent.schmorp.de
2388		3073
2389	=cut	3074	=cut
2390		3075
2391	1	3076	1
2392		3077

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