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Revision 1.338 by root, Tue Nov 23 04:45:59 2010 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# if you prefer function calls, look at the AE manpage for
		13	# an alternative API.
		14
		15	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
12		17
		18	# one-shot or repeating timers
13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
15		21
16	print AnyEvent->now; # prints current event loop time	22	print AnyEvent->now; # prints current event loop time
17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18		24
		25	# POSIX signal
19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });	26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20		27
		28	# child process exit
21	my $w = AnyEvent->child (pid => $pid, cb => sub {	29	my $w = AnyEvent->child (pid => $pid, cb => sub {
22	my ($pid, $status) = @_;	30	my ($pid, $status) = @_;
23	...	31	...
24	});	32	});
		33
		34	# called when event loop idle (if applicable)
		35	my $w = AnyEvent->idle (cb => sub { ... });
25		36
26	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
27	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
28	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
29	# use a condvar in callback mode:	40	# use a condvar in callback mode:
…		…
32	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
33		44
34	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
35	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
36	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.
37		58
38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
39		60
40	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
41	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
…		…
57	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
58	model you use.	79	model you use.
59		80
60	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
61	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
62	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
63	cannot use anything else, as they are simply incompatible to everything	84	cannot use anything else, as they are simply incompatible to everything
64	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
65	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.
66		87
67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
68	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
69	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	90	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
70	your module uses one of those, every user of your module has to use it,	91	your module uses one of those, every user of your module has to use it,
71	too. But if your module uses AnyEvent, it works transparently with all	92	too. But if your module uses AnyEvent, it works transparently with all
72	event models it supports (including stuff like IO::Async, as long as those	93	event models it supports (including stuff like IO::Async, as long as those
73	use one of the supported event loops. It is trivial to add new event loops	94	use one of the supported event loops. It is easy to add new event loops
74	to AnyEvent, too, so it is future-proof).	95	to AnyEvent, too, so it is future-proof).
75		96
76	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
77	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
78	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
79	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
80	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
81	technically possible.	102	technically possible.
82		103
83	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
84	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
90	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
91	model, you should I<not> use this module.	112	model, you should I<not> use this module.
92		113
93	=head1 DESCRIPTION	114	=head1 DESCRIPTION
94		115
95	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
96	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
97	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
98	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
99		120
100	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>
101	module.	122	module.
102		123
103	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
104	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
105	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Impl::Perl>,
106	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
107	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
108	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
109	adaptor should always succeed) in the order given. The first one that can	130	available, the pure-perl L<AnyEvent::Impl::Perl> should always work, so
110	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
111	found, AnyEvent will fall back to a pure-perl event loop, which is not
112	very efficient, but should work everywhere.
113		132
114	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
115	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
116	that model the default. For example:	135	that model the default. For example:
117		136
…		…
119	use AnyEvent;	138	use AnyEvent;
120		139
121	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
122		141
123	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
124	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,
125	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
126		146
127	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called
128	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	148	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
129	explicitly and enjoy the high availability of that event loop :)	149	explicitly and enjoy the high availability of that event loop :)
130		150
…		…
137	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
138	creating a watcher it will immediately "watch" for events and invoke the	158	creating a watcher it will immediately "watch" for events and invoke the
139	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
140	is in control).	160	is in control).
141		161
		162	Note that B<callbacks must not permanently change global variables>
		163	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		164	callbacks must not C<die> >>. The former is good programming practice in
		165	Perl and the latter stems from the fact that exception handling differs
		166	widely between event loops.
		167
142	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
143	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
144	to it).	170	to it).
145		171
146	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.
147		173
148	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
149	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.
150		176
151	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
152		178
153	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
154	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
155	undef $w;	181	undef $w;
156	});	182	});
…		…
159	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
160	declared.	186	declared.
161		187
162	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
163		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
164	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
165	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
166		198
167	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
168	(AnyEvent might or might not keep a reference to this file handle). C<poll>	200	for events (AnyEvent might or might not keep a reference to this file
		201	handle). Note that only file handles pointing to things for which
		202	non-blocking operation makes sense are allowed. This includes sockets,
		203	most character devices, pipes, fifos and so on, but not for example files
		204	or block devices.
		205
169	must be a string that is either C<r> or C<w>, which creates a watcher	206	C<poll> must be a string that is either C<r> or C<w>, which creates a
170	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
171	callback to invoke each time the file handle becomes ready.	209	C<cb> is the callback to invoke each time the file handle becomes ready.
172		210
173	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
174	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
175	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
176		214
177	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.
178	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
179	underlying file descriptor.	217	underlying file descriptor.
180		218
181	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
182	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
183	handles.	221	handles.
184		222
185	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
186	watcher.	224	watcher.
…		…
191	undef $w;	229	undef $w;
192	});	230	});
193		231
194	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
195		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
196	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 >>
197	method with the following mandatory arguments:	243	method with the following mandatory arguments:
198		244
199	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
200	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
…		…
202		248
203	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
204	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
205	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
206		252
207	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
208	parameter, C<interval>, as a strictly positive number (> 0), then the	254	parameter, C<interval>, as a strictly positive number (> 0), then the
209	callback will be invoked regularly at that interval (in fractional	255	callback will be invoked regularly at that interval (in fractional
210	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
211	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.
212		258
213	The callback will be rescheduled before invoking the callback, but no	259	The callback will be rescheduled before invoking the callback, but no
214	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
215	only approximate.	261	only approximate.
216		262
217	Example: fire an event after 7.7 seconds.	263	Example: fire an event after 7.7 seconds.
218		264
219	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
237		283
238	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
239	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
240	"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
241	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
242	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.
243		289
244	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
245	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
246	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)
247	timers.	293	timers.
248		294
249	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
250	AnyEvent API.	296	AnyEvent API.
…		…
272	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
273	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
274		320
275	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
276	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
277	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
278		324
279	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
280	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
281		327
282	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>
283	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
284		330
285	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
286	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
287	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
288	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
289	after three seconds.	335	after three seconds.
290		336
…		…
308	In either case, if you care (and in most cases, you don't), then you	354	In either case, if you care (and in most cases, you don't), then you
309	can get whatever behaviour you want with any event loop, by taking the	355	can get whatever behaviour you want with any event loop, by taking the
310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311	account.	357	account.
312		358
		359	=item AnyEvent->now_update
		360
		361	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		362	the current time for each loop iteration (see the discussion of L<<
		363	AnyEvent->now >>, above).
		364
		365	When a callback runs for a long time (or when the process sleeps), then
		366	this "current" time will differ substantially from the real time, which
		367	might affect timers and time-outs.
		368
		369	When this is the case, you can call this method, which will update the
		370	event loop's idea of "current time".
		371
		372	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		373	when mod_perl executes the script, then the event loop will have the wrong
		374	idea about the "current time" (being potentially far in the past, when the
		375	script ran the last time). In that case you should arrange a call to C<<
		376	AnyEvent->now_update >> each time the web server process wakes up again
		377	(e.g. at the start of your script, or in a handler).
		378
		379	Note that updating the time I<might> cause some events to be handled.
		380
313	=back	381	=back
314		382
315	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
316		386
317	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
318	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
319	callback to be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
320		390
…		…
326	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
327	that it might take a while until the signal gets handled by the process,	397	that it might take a while until the signal gets handled by the process,
328	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
329		399
330	The main advantage of using these watchers is that you can share a signal	400	The main advantage of using these watchers is that you can share a signal
331	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
332		403
333	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
334	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
335		407
336	Example: exit on SIGINT	408	Example: exit on SIGINT
337		409
338	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
339		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		437	variable can be changed only before the first signal watcher is created,
		438	and should be left alone otherwise. This variable determines how often
		439	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		440	will cause fewer spurious wake-ups, which is better for power and CPU
		441	saving.
		442
		443	All these problems can be avoided by installing the optional
		444	L<Async::Interrupt> module, which works with most event loops. It will not
		445	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		446	(and not with L<POE> currently, as POE does its own workaround with
		447	one-second latency). For those, you just have to suffer the delays.
		448
340	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
341		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
342	You can also watch on a child process exit and catch its exit status.	453	You can also watch for a child process exit and catch its exit status.
343		454
344	The child process is specified by the C<pid> argument (if set to C<0>, it	455	The child process is specified by the C<pid> argument (on some backends,
345	watches for any child process exit). The watcher will triggered only when	456	using C<0> watches for any child process exit, on others this will
346	the child process has finished and an exit status is available, not on	457	croak). The watcher will be triggered only when the child process has
347	any trace events (stopped/continued).	458	finished and an exit status is available, not on any trace events
		459	(stopped/continued).
348		460
349	The callback will be called with the pid and exit status (as returned by	461	The callback will be called with the pid and exit status (as returned by
350	waitpid), so unlike other watcher types, you I<can> rely on child watcher	462	waitpid), so unlike other watcher types, you I<can> rely on child watcher
351	callback arguments.	463	callback arguments.
352		464
…		…
357		469
358	There is a slight catch to child watchers, however: you usually start them	470	There is a slight catch to child watchers, however: you usually start them
359	I<after> the child process was created, and this means the process could	471	I<after> the child process was created, and this means the process could
360	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
361		473
362	Not all event models handle this correctly (POE doesn't), but even for	474	Not all event models handle this correctly (neither POE nor IO::Async do,
		475	see their AnyEvent::Impl manpages for details), but even for event models
363	event models that I<do> handle this correctly, they usually need to be	476	that I<do> handle this correctly, they usually need to be loaded before
364	loaded before the process exits (i.e. before you fork in the first place).	477	the process exits (i.e. before you fork in the first place). AnyEvent's
		478	pure perl event loop handles all cases correctly regardless of when you
		479	start the watcher.
365		480
366	This means you cannot create a child watcher as the very first thing in an	481	This means you cannot create a child watcher as the very first
367	AnyEvent program, you I<have> to create at least one watcher before you	482	thing in an AnyEvent program, you I<have> to create at least one
368	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	483	watcher before you C<fork> the child (alternatively, you can call
		484	C<AnyEvent::detect>).
		485
		486	As most event loops do not support waiting for child events, they will be
		487	emulated by AnyEvent in most cases, in which the latency and race problems
		488	mentioned in the description of signal watchers apply.
369		489
370	Example: fork a process and wait for it	490	Example: fork a process and wait for it
371		491
372	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
373		493
…		…
383	);	503	);
384		504
385	# do something else, then wait for process exit	505	# do something else, then wait for process exit
386	$done->recv;	506	$done->recv;
387		507
		508	=head2 IDLE WATCHERS
		509
		510	$w = AnyEvent->idle (cb => <callback>);
		511
		512	This will repeatedly invoke the callback after the process becomes idle,
		513	until either the watcher is destroyed or new events have been detected.
		514
		515	Idle watchers are useful when there is a need to do something, but it
		516	is not so important (or wise) to do it instantly. The callback will be
		517	invoked only when there is "nothing better to do", which is usually
		518	defined as "all outstanding events have been handled and no new events
		519	have been detected". That means that idle watchers ideally get invoked
		520	when the event loop has just polled for new events but none have been
		521	detected. Instead of blocking to wait for more events, the idle watchers
		522	will be invoked.
		523
		524	Unfortunately, most event loops do not really support idle watchers (only
		525	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		526	will simply call the callback "from time to time".
		527
		528	Example: read lines from STDIN, but only process them when the
		529	program is otherwise idle:
		530
		531	my @lines; # read data
		532	my $idle_w;
		533	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		534	push @lines, scalar <STDIN>;
		535
		536	# start an idle watcher, if not already done
		537	$idle_w ||= AnyEvent->idle (cb => sub {
		538	# handle only one line, when there are lines left
		539	if (my $line = shift @lines) {
		540	print "handled when idle: $line";
		541	} else {
		542	# otherwise disable the idle watcher again
		543	undef $idle_w;
		544	}
		545	});
		546	});
		547
388	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
389		554
390	If you are familiar with some event loops you will know that all of them	555	If you are familiar with some event loops you will know that all of them
391	require you to run some blocking "loop", "run" or similar function that	556	require you to run some blocking "loop", "run" or similar function that
392	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
393		558
394	AnyEvent is different, it expects somebody else to run the event loop and	559	AnyEvent is slightly different: it expects somebody else to run the event
395	will only block when necessary (usually when told by the user).	560	loop and will only block when necessary (usually when told by the user).
396		561
397	The instrument to do that is called a "condition variable", so called	562	The tool to do that is called a "condition variable", so called because
398	because they represent a condition that must become true.	563	they represent a condition that must become true.
		564
		565	Now is probably a good time to look at the examples further below.
399		566
400	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
401	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
402
403	C<cb>, which specifies a callback to be called when the condition variable	569	C<cb>, which specifies a callback to be called when the condition variable
404	becomes true, with the condition variable as the first argument (but not	570	becomes true, with the condition variable as the first argument (but not
405	the results).	571	the results).
406		572
407	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
408	by calling the C<send> method (or calling the condition variable as if it	574	by calling the C<send> method (or calling the condition variable as if it
409	were a callback, read about the caveats in the description for the C<<	575	were a callback, read about the caveats in the description for the C<<
410	->send >> method).	576	->send >> method).
411		577
412	Condition variables are similar to callbacks, except that you can	578	Since condition variables are the most complex part of the AnyEvent API, here are
413	optionally wait for them. They can also be called merge points - points	579	some different mental models of what they are - pick the ones you can connect to:
414	in time where multiple outstanding events have been processed. And yet	580
415	another way to call them is transactions - each condition variable can be	581	=over 4
416	used to represent a transaction, which finishes at some point and delivers	582
417	a result.	583	=item * Condition variables are like callbacks - you can call them (and pass them instead
		584	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		585
		586	=item * Condition variables are signals - one side can emit or send them,
		587	the other side can wait for them, or install a handler that is called when
		588	the signal fires.
		589
		590	=item * Condition variables are like "Merge Points" - points in your program
		591	where you merge multiple independent results/control flows into one.
		592
		593	=item * Condition variables represent a transaction - functions that start
		594	some kind of transaction can return them, leaving the caller the choice
		595	between waiting in a blocking fashion, or setting a callback.
		596
		597	=item * Condition variables represent future values, or promises to deliver
		598	some result, long before the result is available.
		599
		600	=back
418		601
419	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
420	for example, if you write a module that does asynchronous http requests,	603	for example, if you write a module that does asynchronous http requests,
421	then a condition variable would be the ideal candidate to signal the	604	then a condition variable would be the ideal candidate to signal the
422	availability of results. The user can either act when the callback is	605	availability of results. The user can either act when the callback is
…		…
435		618
436	Condition variables are represented by hash refs in perl, and the keys	619	Condition variables are represented by hash refs in perl, and the keys
437	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	620	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
438	easy (it is often useful to build your own transaction class on top of	621	easy (it is often useful to build your own transaction class on top of
439	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	622	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
440	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
441		624
442	There are two "sides" to a condition variable - the "producer side" which	625	There are two "sides" to a condition variable - the "producer side" which
443	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
444	for the send to occur.	627	for the send to occur.
445		628
446	Example: wait for a timer.	629	Example: wait for a timer.
447		630
448	# wait till the result is ready	631	# condition: "wait till the timer is fired"
449	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
450		633
451	# do something such as adding a timer	634	# create the timer - we could wait for, say
452	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
453	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
454	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
455	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
456	after => 1,	639	after => 1,
457	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
458	);	641	);
459		642
460	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
461	# calls send	644	# calls ->send
462	$result_ready->recv;	645	$timer_fired->recv;
463		646
464	Example: wait for a timer, but take advantage of the fact that	647	Example: wait for a timer, but take advantage of the fact that condition
465	condition variables are also code references.	648	variables are also callable directly.
466		649
467	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
468	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
469	$done->recv;	652	$done->recv;
470		653
…		…
476		659
477	...	660	...
478		661
479	my @info = $couchdb->info->recv;	662	my @info = $couchdb->info->recv;
480		663
481	And this is how you would just ste a callback to be called whenever the	664	And this is how you would just set a callback to be called whenever the
482	results are available:	665	results are available:
483		666
484	$couchdb->info->cb (sub {	667	$couchdb->info->cb (sub {
485	my @info = $_[0]->recv;	668	my @info = $_[0]->recv;
486	});	669	});
…		…
504	immediately from within send.	687	immediately from within send.
505		688
506	Any arguments passed to the C<send> call will be returned by all	689	Any arguments passed to the C<send> call will be returned by all
507	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
508		691
509	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
510	(as a code reference). Calling them directly is the same as calling	693	they were a code reference). Calling them directly is the same as calling
511	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
512	overloading, so as tempting as it may be, passing a condition variable
513	instead of a callback does not work. Both the pure perl and EV loops
514	support overloading, however, as well as all functions that use perl to
515	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
516	example).
517		695
518	=item $cv->croak ($error)	696	=item $cv->croak ($error)
519		697
520	Similar to send, but causes all call's to C<< ->recv >> to invoke	698	Similar to send, but causes all calls to C<< ->recv >> to invoke
521	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
522		700
523	This can be used to signal any errors to the condition variable	701	This can be used to signal any errors to the condition variable
524	user/consumer.	702	user/consumer. Doing it this way instead of calling C<croak> directly
		703	delays the error detection, but has the overwhelming advantage that it
		704	diagnoses the error at the place where the result is expected, and not
		705	deep in some event callback with no connection to the actual code causing
		706	the problem.
525		707
526	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
527		709
528	=item $cv->end	710	=item $cv->end
529
530	These two methods are EXPERIMENTAL and MIGHT CHANGE.
531		711
532	These two methods can be used to combine many transactions/events into	712	These two methods can be used to combine many transactions/events into
533	one. For example, a function that pings many hosts in parallel might want	713	one. For example, a function that pings many hosts in parallel might want
534	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
535		715
536	Every call to C<< ->begin >> will increment a counter, and every call to	716	Every call to C<< ->begin >> will increment a counter, and every call to
537	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	717	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
538	>>, the (last) callback passed to C<begin> will be executed. That callback	718	>>, the (last) callback passed to C<begin> will be executed, passing the
539	is I<supposed> to call C<< ->send >>, but that is not required. If no	719	condvar as first argument. That callback is I<supposed> to call C<< ->send
540	callback was set, C<send> will be called without any arguments.	720	>>, but that is not required. If no group callback was set, C<send> will
		721	be called without any arguments.
541		722
542	Let's clarify this with the ping example:	723	You can think of C<< $cv->send >> giving you an OR condition (one call
		724	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		725	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		726
		727	Let's start with a simple example: you have two I/O watchers (for example,
		728	STDOUT and STDERR for a program), and you want to wait for both streams to
		729	close before activating a condvar:
543		730
544	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
545		732
		733	$cv->begin; # first watcher
		734	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		735	defined sysread $fh1, my $buf, 4096
		736	or $cv->end;
		737	});
		738
		739	$cv->begin; # second watcher
		740	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		741	defined sysread $fh2, my $buf, 4096
		742	or $cv->end;
		743	});
		744
		745	$cv->recv;
		746
		747	This works because for every event source (EOF on file handle), there is
		748	one call to C<begin>, so the condvar waits for all calls to C<end> before
		749	sending.
		750
		751	The ping example mentioned above is slightly more complicated, as the
		752	there are results to be passwd back, and the number of tasks that are
		753	begun can potentially be zero:
		754
		755	my $cv = AnyEvent->condvar;
		756
546	my %result;	757	my %result;
547	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
548		759
549	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
550	$cv->begin;	761	$cv->begin;
551	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
552	$result{$host} = ...;	763	$result{$host} = ...;
…		…
567	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
568	to be called once the counter reaches C<0>, and second, it ensures that	779	to be called once the counter reaches C<0>, and second, it ensures that
569	C<send> is called even when C<no> hosts are being pinged (the loop	780	C<send> is called even when C<no> hosts are being pinged (the loop
570	doesn't execute once).	781	doesn't execute once).
571		782
572	This is the general pattern when you "fan out" into multiple subrequests:	783	This is the general pattern when you "fan out" into multiple (but
573	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	784	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
574	is called at least once, and then, for each subrequest you start, call	785	the callback and ensure C<end> is called at least once, and then, for each
575	C<begin> and for each subrequest you finish, call C<end>.	786	subrequest you start, call C<begin> and for each subrequest you finish,
		787	call C<end>.
576		788
577	=back	789	=back
578		790
579	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
580		792
…		…
584	=over 4	796	=over 4
585		797
586	=item $cv->recv	798	=item $cv->recv
587		799
588	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
589	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
590	normally.	802	normally.
591		803
592	You can only wait once on a condition - additional calls are valid but	804	You can only wait once on a condition - additional calls are valid but
593	will return immediately.	805	will return immediately.
594		806
…		…
596	function will call C<croak>.	808	function will call C<croak>.
597		809
598	In list context, all parameters passed to C<send> will be returned,	810	In list context, all parameters passed to C<send> will be returned,
599	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
600		812
		813	Note that doing a blocking wait in a callback is not supported by any
		814	event loop, that is, recursive invocation of a blocking C<< ->recv
		815	>> is not allowed, and the C<recv> call will C<croak> if such a
		816	condition is detected. This condition can be slightly loosened by using
		817	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		818	any thread that doesn't run the event loop itself.
		819
601	Not all event models support a blocking wait - some die in that case	820	Not all event models support a blocking wait - some die in that case
602	(programs might want to do that to stay interactive), so I<if you are	821	(programs might want to do that to stay interactive), so I<if you are
603	using this from a module, never require a blocking wait>, but let the	822	using this from a module, never require a blocking wait>. Instead, let the
604	caller decide whether the call will block or not (for example, by coupling	823	caller decide whether the call will block or not (for example, by coupling
605	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
606	callbacks so the caller knows that getting the result will not block,	825	callbacks so the caller knows that getting the result will not block,
607	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
608		827
609	Another reason I<never> to C<< ->recv >> in a module is that you cannot
610	sensibly have two C<< ->recv >>'s in parallel, as that would require
611	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
612	can supply.
613
614	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
615	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
616	versions and also integrates coroutines into AnyEvent, making blocking
617	C<< ->recv >> calls perfectly safe as long as they are done from another
618	coroutine (one that doesn't run the event loop).
619
620	You can ensure that C<< -recv >> never blocks by setting a callback and	828	You can ensure that C<< ->recv >> never blocks by setting a callback and
621	only calling C<< ->recv >> from within that callback (or at a later	829	only calling C<< ->recv >> from within that callback (or at a later
622	time). This will work even when the event loop does not support blocking	830	time). This will work even when the event loop does not support blocking
623	waits otherwise.	831	waits otherwise.
624		832
625	=item $bool = $cv->ready	833	=item $bool = $cv->ready
…		…
631		839
632	This is a mutator function that returns the callback set and optionally	840	This is a mutator function that returns the callback set and optionally
633	replaces it before doing so.	841	replaces it before doing so.
634		842
635	The callback will be called when the condition becomes "true", i.e. when	843	The callback will be called when the condition becomes "true", i.e. when
636	C<send> or C<croak> are called, with the only argument being the condition	844	C<send> or C<croak> are called, with the only argument being the
637	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
638	is guaranteed not to block.	846	callback is called immediately when it is set. Calling C<recv> inside
		847	the callback or at any later time is guaranteed not to block.
639		848
640	=back	849	=back
641		850
		851	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		852
		853	The available backend classes are (every class has its own manpage):
		854
		855	=over 4
		856
		857	=item Backends that are autoprobed when no other event loop can be found.
		858
		859	EV is the preferred backend when no other event loop seems to be in
		860	use. If EV is not installed, then AnyEvent will fall back to its own
		861	pure-perl implementation, which is available everywhere as it comes with
		862	AnyEvent itself.
		863
		864	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		865	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		866
		867	=item Backends that are transparently being picked up when they are used.
		868
		869	These will be used if they are already loaded when the first watcher
		870	is created, in which case it is assumed that the application is using
		871	them. This means that AnyEvent will automatically pick the right backend
		872	when the main program loads an event module before anything starts to
		873	create watchers. Nothing special needs to be done by the main program.
		874
		875	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		876	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		877	AnyEvent::Impl::Tk based on Tk, very broken.
		878	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		879	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		880	AnyEvent::Impl::Irssi used when running within irssi.
		881
		882	=item Backends with special needs.
		883
		884	Qt requires the Qt::Application to be instantiated first, but will
		885	otherwise be picked up automatically. As long as the main program
		886	instantiates the application before any AnyEvent watchers are created,
		887	everything should just work.
		888
		889	AnyEvent::Impl::Qt based on Qt.
		890
		891	Support for IO::Async can only be partial, as it is too broken and
		892	architecturally limited to even support the AnyEvent API. It also
		893	is the only event loop that needs the loop to be set explicitly, so
		894	it can only be used by a main program knowing about AnyEvent. See
		895	L<AnyEvent::Impl::IOAsync> for the gory details.
		896
		897	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		898
		899	=item Event loops that are indirectly supported via other backends.
		900
		901	Some event loops can be supported via other modules:
		902
		903	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		904
		905	B<WxWidgets> has no support for watching file handles. However, you can
		906	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		907	polls 20 times per second, which was considered to be too horrible to even
		908	consider for AnyEvent.
		909
		910	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		911	backend, so it can be supported through POE.
		912
		913	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		914	load L<POE> when detecting them, in the hope that POE will pick them up,
		915	in which case everything will be automatic.
		916
		917	=back
		918
642	=head1 GLOBAL VARIABLES AND FUNCTIONS	919	=head1 GLOBAL VARIABLES AND FUNCTIONS
643		920
		921	These are not normally required to use AnyEvent, but can be useful to
		922	write AnyEvent extension modules.
		923
644	=over 4	924	=over 4
645		925
646	=item $AnyEvent::MODEL	926	=item $AnyEvent::MODEL
647		927
648	Contains C<undef> until the first watcher is being created. Then it	928	Contains C<undef> until the first watcher is being created, before the
		929	backend has been autodetected.
		930
649	contains the event model that is being used, which is the name of the	931	Afterwards it contains the event model that is being used, which is the
650	Perl class implementing the model. This class is usually one of the	932	name of the Perl class implementing the model. This class is usually one
651	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	933	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
652	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	934	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
653		935	will be C<urxvt::anyevent>).
654	The known classes so far are:
655
656	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
657	AnyEvent::Impl::Event based on Event, second best choice.
658	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
659	AnyEvent::Impl::Glib based on Glib, third-best choice.
660	AnyEvent::Impl::Tk based on Tk, very bad choice.
661	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
662	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
663	AnyEvent::Impl::POE based on POE, not generic enough for full support.
664
665	There is no support for WxWidgets, as WxWidgets has no support for
666	watching file handles. However, you can use WxWidgets through the
667	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
668	second, which was considered to be too horrible to even consider for
669	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
670	it's adaptor.
671
672	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
673	autodetecting them.
674		936
675	=item AnyEvent::detect	937	=item AnyEvent::detect
676		938
677	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	939	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
678	if necessary. You should only call this function right before you would	940	if necessary. You should only call this function right before you would
679	have created an AnyEvent watcher anyway, that is, as late as possible at	941	have created an AnyEvent watcher anyway, that is, as late as possible at
680	runtime.	942	runtime, and not e.g. during initialisation of your module.
		943
		944	If you need to do some initialisation before AnyEvent watchers are
		945	created, use C<post_detect>.
681		946
682	=item $guard = AnyEvent::post_detect { BLOCK }	947	=item $guard = AnyEvent::post_detect { BLOCK }
683		948
684	Arranges for the code block to be executed as soon as the event model is	949	Arranges for the code block to be executed as soon as the event model is
685	autodetected (or immediately if this has already happened).	950	autodetected (or immediately if that has already happened).
		951
		952	The block will be executed I<after> the actual backend has been detected
		953	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		954	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		955	other initialisations - see the sources of L<AnyEvent::Strict> or
		956	L<AnyEvent::AIO> to see how this is used.
		957
		958	The most common usage is to create some global watchers, without forcing
		959	event module detection too early, for example, L<AnyEvent::AIO> creates
		960	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		961	avoid autodetecting the event module at load time.
686		962
687	If called in scalar or list context, then it creates and returns an object	963	If called in scalar or list context, then it creates and returns an object
688	that automatically removes the callback again when it is destroyed. See	964	that automatically removes the callback again when it is destroyed (or
		965	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
689	L<Coro::BDB> for a case where this is useful.	966	a case where this is useful.
		967
		968	Example: Create a watcher for the IO::AIO module and store it in
		969	C<$WATCHER>, but do so only do so after the event loop is initialised.
		970
		971	our WATCHER;
		972
		973	my $guard = AnyEvent::post_detect {
		974	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		975	};
		976
		977	# the ||= is important in case post_detect immediately runs the block,
		978	# as to not clobber the newly-created watcher. assigning both watcher and
		979	# post_detect guard to the same variable has the advantage of users being
		980	# able to just C<undef $WATCHER> if the watcher causes them grief.
		981
		982	$WATCHER ||= $guard;
690		983
691	=item @AnyEvent::post_detect	984	=item @AnyEvent::post_detect
692		985
693	If there are any code references in this array (you can C<push> to it	986	If there are any code references in this array (you can C<push> to it
694	before or after loading AnyEvent), then they will called directly after	987	before or after loading AnyEvent), then they will be called directly
695	the event loop has been chosen.	988	after the event loop has been chosen.
696		989
697	You should check C<$AnyEvent::MODEL> before adding to this array, though:	990	You should check C<$AnyEvent::MODEL> before adding to this array, though:
698	if it contains a true value then the event loop has already been detected,	991	if it is defined then the event loop has already been detected, and the
699	and the array will be ignored.	992	array will be ignored.
700		993
701	Best use C<AnyEvent::post_detect { BLOCK }> instead.	994	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		995	it, as it takes care of these details.
		996
		997	This variable is mainly useful for modules that can do something useful
		998	when AnyEvent is used and thus want to know when it is initialised, but do
		999	not need to even load it by default. This array provides the means to hook
		1000	into AnyEvent passively, without loading it.
		1001
		1002	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1003	together, you could put this into Coro (this is the actual code used by
		1004	Coro to accomplish this):
		1005
		1006	if (defined $AnyEvent::MODEL) {
		1007	# AnyEvent already initialised, so load Coro::AnyEvent
		1008	require Coro::AnyEvent;
		1009	} else {
		1010	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1011	# as soon as it is
		1012	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1013	}
702		1014
703	=back	1015	=back
704		1016
705	=head1 WHAT TO DO IN A MODULE	1017	=head1 WHAT TO DO IN A MODULE
706		1018
…		…
717	because it will stall the whole program, and the whole point of using	1029	because it will stall the whole program, and the whole point of using
718	events is to stay interactive.	1030	events is to stay interactive.
719		1031
720	It is fine, however, to call C<< ->recv >> when the user of your module	1032	It is fine, however, to call C<< ->recv >> when the user of your module
721	requests it (i.e. if you create a http request object ad have a method	1033	requests it (i.e. if you create a http request object ad have a method
722	called C<results> that returns the results, it should call C<< ->recv >>	1034	called C<results> that returns the results, it may call C<< ->recv >>
723	freely, as the user of your module knows what she is doing. always).	1035	freely, as the user of your module knows what she is doing. Always).
724		1036
725	=head1 WHAT TO DO IN THE MAIN PROGRAM	1037	=head1 WHAT TO DO IN THE MAIN PROGRAM
726		1038
727	There will always be a single main program - the only place that should	1039	There will always be a single main program - the only place that should
728	dictate which event model to use.	1040	dictate which event model to use.
729		1041
730	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1042	If the program is not event-based, it need not do anything special, even
731	do anything special (it does not need to be event-based) and let AnyEvent	1043	when it depends on a module that uses an AnyEvent. If the program itself
732	decide which implementation to chose if some module relies on it.	1044	uses AnyEvent, but does not care which event loop is used, all it needs
		1045	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1046	available loop implementation.
733		1047
734	If the main program relies on a specific event model - for example, in	1048	If the main program relies on a specific event model - for example, in
735	Gtk2 programs you have to rely on the Glib module - you should load the	1049	Gtk2 programs you have to rely on the Glib module - you should load the
736	event module before loading AnyEvent or any module that uses it: generally	1050	event module before loading AnyEvent or any module that uses it: generally
737	speaking, you should load it as early as possible. The reason is that	1051	speaking, you should load it as early as possible. The reason is that
738	modules might create watchers when they are loaded, and AnyEvent will	1052	modules might create watchers when they are loaded, and AnyEvent will
739	decide on the event model to use as soon as it creates watchers, and it	1053	decide on the event model to use as soon as it creates watchers, and it
740	might chose the wrong one unless you load the correct one yourself.	1054	might choose the wrong one unless you load the correct one yourself.
741		1055
742	You can chose to use a pure-perl implementation by loading the	1056	You can chose to use a pure-perl implementation by loading the
743	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1057	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
744	everywhere, but letting AnyEvent chose the model is generally better.	1058	everywhere, but letting AnyEvent chose the model is generally better.
745		1059
…		…
761		1075
762		1076
763	=head1 OTHER MODULES	1077	=head1 OTHER MODULES
764		1078
765	The following is a non-exhaustive list of additional modules that use	1079	The following is a non-exhaustive list of additional modules that use
766	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1080	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
767	in the same program. Some of the modules come with AnyEvent, some are	1081	modules and other event loops in the same program. Some of the modules
768	available via CPAN.	1082	come as part of AnyEvent, the others are available via CPAN.
769		1083
770	=over 4	1084	=over 4
771		1085
772	=item L<AnyEvent::Util>	1086	=item L<AnyEvent::Util>
773		1087
774	Contains various utility functions that replace often-used but blocking	1088	Contains various utility functions that replace often-used blocking
775	functions such as C<inet_aton> by event-/callback-based versions.	1089	functions such as C<inet_aton> with event/callback-based versions.
776		1090
777	=item L<AnyEvent::Socket>	1091	=item L<AnyEvent::Socket>
778		1092
779	Provides various utility functions for (internet protocol) sockets,	1093	Provides various utility functions for (internet protocol) sockets,
780	addresses and name resolution. Also functions to create non-blocking tcp	1094	addresses and name resolution. Also functions to create non-blocking tcp
…		…
782		1096
783	=item L<AnyEvent::Handle>	1097	=item L<AnyEvent::Handle>
784		1098
785	Provide read and write buffers, manages watchers for reads and writes,	1099	Provide read and write buffers, manages watchers for reads and writes,
786	supports raw and formatted I/O, I/O queued and fully transparent and	1100	supports raw and formatted I/O, I/O queued and fully transparent and
787	non-blocking SSL/TLS.	1101	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
788		1102
789	=item L<AnyEvent::DNS>	1103	=item L<AnyEvent::DNS>
790		1104
791	Provides rich asynchronous DNS resolver capabilities.	1105	Provides rich asynchronous DNS resolver capabilities.
792		1106
		1107	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1108
		1109	Implement event-based interfaces to the protocols of the same name (for
		1110	the curious, IGS is the International Go Server and FCP is the Freenet
		1111	Client Protocol).
		1112
		1113	=item L<AnyEvent::Handle::UDP>
		1114
		1115	Here be danger!
		1116
		1117	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1118	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1119	its use of a stream-based API with a protocol that isn't streamable, that
		1120	the only way to improve it is to delete it.
		1121
		1122	It features data corruption (but typically only under load) and general
		1123	confusion. On top, the author is not only clueless about UDP but also
		1124	fact-resistant - some gems of his understanding: "connect doesn't work
		1125	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1126	packets", "I don't need to implement proper error checking as UDP doesn't
		1127	support error checking" and so on - he doesn't even understand what's
		1128	wrong with his module when it is explained to him.
		1129
793	=item L<AnyEvent::HTTP>	1130	=item L<AnyEvent::DBI>
794		1131
795	A simple-to-use HTTP library that is capable of making a lot of concurrent	1132	Executes L<DBI> requests asynchronously in a proxy process for you,
796	HTTP requests.	1133	notifying you in an event-based way when the operation is finished.
		1134
		1135	=item L<AnyEvent::AIO>
		1136
		1137	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1138	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1139	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1140	file I/O, and much more.
797		1141
798	=item L<AnyEvent::HTTPD>	1142	=item L<AnyEvent::HTTPD>
799		1143
800	Provides a simple web application server framework.	1144	A simple embedded webserver.
801		1145
802	=item L<AnyEvent::FastPing>	1146	=item L<AnyEvent::FastPing>
803		1147
804	The fastest ping in the west.	1148	The fastest ping in the west.
805		1149
806	=item L<AnyEvent::DBI>
807
808	Executes L<DBI> requests asynchronously in a proxy process.
809
810	=item L<AnyEvent::AIO>
811
812	Truly asynchronous I/O, should be in the toolbox of every event
813	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
814	together.
815
816	=item L<AnyEvent::BDB>
817
818	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
819	L<BDB> and AnyEvent together.
820
821	=item L<AnyEvent::GPSD>
822
823	A non-blocking interface to gpsd, a daemon delivering GPS information.
824
825	=item L<AnyEvent::IGS>
826
827	A non-blocking interface to the Internet Go Server protocol (used by
828	L<App::IGS>).
829
830	=item L<AnyEvent::IRC>
831
832	AnyEvent based IRC client module family (replacing the older Net::IRC3).
833
834	=item L<Net::XMPP2>
835
836	AnyEvent based XMPP (Jabber protocol) module family.
837
838	=item L<Net::FCP>
839
840	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
841	of AnyEvent.
842
843	=item L<Event::ExecFlow>
844
845	High level API for event-based execution flow control.
846
847	=item L<Coro>	1150	=item L<Coro>
848		1151
849	Has special support for AnyEvent via L<Coro::AnyEvent>.	1152	Has special support for AnyEvent via L<Coro::AnyEvent>.
850		1153
851	=item L<IO::Lambda>
852
853	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
854
855	=back	1154	=back
856		1155
857	=cut	1156	=cut
858		1157
859	package AnyEvent;	1158	package AnyEvent;
860		1159
861	no warnings;	1160	# basically a tuned-down version of common::sense
862	use strict qw(vars subs);	1161	sub common_sense {
		1162	# from common:.sense 3.3
		1163	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf3\x0f\xc0\xf0\xfc\x33\x00";
		1164	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1165	$^H |= 0x00000600;
		1166	}
863		1167
		1168	BEGIN { AnyEvent::common_sense }
		1169
864	use Carp;	1170	use Carp ();
865		1171
866	our $VERSION = 4.341;	1172	our $VERSION = '5.29';
867	our $MODEL;	1173	our $MODEL;
868		1174
869	our $AUTOLOAD;	1175	our $AUTOLOAD;
870	our @ISA;	1176	our @ISA;
871		1177
872	our @REGISTRY;	1178	our @REGISTRY;
873		1179
874	our $WIN32;	1180	our $VERBOSE;
875		1181
876	BEGIN {	1182	BEGIN {
877	my $win32 = ! ! ($^O =~ /mswin32/i);	1183	require "AnyEvent/constants.pl";
878	eval "sub WIN32(){ $win32 }";
879	}
880		1184
		1185	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1186
		1187	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1188	if ${^TAINT};
		1189
881	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1190	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1191
		1192	}
		1193
		1194	our $MAX_SIGNAL_LATENCY = 10;
882		1195
883	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1196	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
884		1197
885	{	1198	{
886	my $idx;	1199	my $idx;
…		…
888	for reverse split /\s*,\s*/,	1201	for reverse split /\s*,\s*/,
889	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1202	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
890	}	1203	}
891		1204
892	my @models = (	1205	my @models = (
893	[EV:: => AnyEvent::Impl::EV::],	1206	[EV:: => AnyEvent::Impl::EV:: , 1],
894	[Event:: => AnyEvent::Impl::Event::],
895	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1207	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
896	# everything below here will not be autoprobed	1208	# everything below here will not (normally) be autoprobed
897	# as the pureperl backend should work everywhere	1209	# as the pureperl backend should work everywhere
898	# and is usually faster	1210	# and is usually faster
		1211	[Event:: => AnyEvent::Impl::Event::, 1],
		1212	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1213	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1214	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
899	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1215	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
900	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
901	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
902	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1216	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
903	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1217	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
904	[Wx:: => AnyEvent::Impl::POE::],	1218	[Wx:: => AnyEvent::Impl::POE::],
905	[Prima:: => AnyEvent::Impl::POE::],	1219	[Prima:: => AnyEvent::Impl::POE::],
		1220	# IO::Async is just too broken - we would need workarounds for its
		1221	# byzantine signal and broken child handling, among others.
		1222	# IO::Async is rather hard to detect, as it doesn't have any
		1223	# obvious default class.
		1224	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1225	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1226	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1227	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
906	);	1228	);
907		1229
908	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1230	our %method = map +($_ => 1),
		1231	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
909		1232
910	our @post_detect;	1233	our @post_detect;
911		1234
912	sub post_detect(&) {	1235	sub post_detect(&) {
913	my ($cb) = @_;	1236	my ($cb) = @_;
914		1237
915	if ($MODEL) {
916	$cb->();
917
918	1
919	} else {
920	push @post_detect, $cb;	1238	push @post_detect, $cb;
921		1239
922	defined wantarray	1240	defined wantarray
923	? bless \$cb, "AnyEvent::Util::PostDetect"	1241	? bless \$cb, "AnyEvent::Util::postdetect"
924	: ()	1242	: ()
		1243	}
		1244
		1245	sub AnyEvent::Util::postdetect::DESTROY {
		1246	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1247	}
		1248
		1249	sub detect() {
		1250	# free some memory
		1251	*detect = sub () { $MODEL };
		1252
		1253	local $!; # for good measure
		1254	local $SIG{__DIE__};
		1255
		1256	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1257	my $model = "AnyEvent::Impl::$1";
		1258	if (eval "require $model") {
		1259	$MODEL = $model;
		1260	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
		1261	} else {
		1262	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
		1263	}
925	}	1264	}
926	}
927		1265
928	sub AnyEvent::Util::PostDetect::DESTROY {	1266	# check for already loaded models
929	@post_detect = grep $_ != ${$_[0]}, @post_detect;
930	}
931
932	sub detect() {
933	unless ($MODEL) {	1267	unless ($MODEL) {
934	no strict 'refs';	1268	for (@REGISTRY, @models) {
935	local $SIG{__DIE__};	1269	my ($package, $model) = @$_;
936		1270	if (${"$package\::VERSION"} > 0) {
937	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
938	my $model = "AnyEvent::Impl::$1";
939	if (eval "require $model") {	1271	if (eval "require $model") {
940	$MODEL = $model;	1272	$MODEL = $model;
941	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1273	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
942	} else {	1274	last;
943	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1275	}
944	}	1276	}
945	}	1277	}
946		1278
947	# check for already loaded models
948	unless ($MODEL) {	1279	unless ($MODEL) {
		1280	# try to autoload a model
949	for (@REGISTRY, @models) {	1281	for (@REGISTRY, @models) {
950	my ($package, $model) = @$_;	1282	my ($package, $model, $autoload) = @$_;
		1283	if (
		1284	$autoload
		1285	and eval "require $package"
951	if (${"$package\::VERSION"} > 0) {	1286	and ${"$package\::VERSION"} > 0
952	if (eval "require $model") {	1287	and eval "require $model"
		1288	) {
953	$MODEL = $model;	1289	$MODEL = $model;
954	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1290	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
955	last;	1291	last;
956	}
957	}	1292	}
958	}	1293	}
959		1294
960	unless ($MODEL) {
961	# try to load a model
962
963	for (@REGISTRY, @models) {
964	my ($package, $model) = @$_;
965	if (eval "require $package"
966	and ${"$package\::VERSION"} > 0
967	and eval "require $model") {
968	$MODEL = $model;
969	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
970	last;
971	}
972	}
973
974	$MODEL	1295	$MODEL
975	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1296	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
976	}
977	}	1297	}
978
979	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
980
981	unshift @ISA, $MODEL;
982
983	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
984
985	(shift @post_detect)->() while @post_detect;
986	}	1298	}
		1299
		1300	@models = (); # free probe data
		1301
		1302	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1303	unshift @ISA, $MODEL;
		1304
		1305	# now nuke some methods that are overridden by the backend.
		1306	# SUPER is not allowed.
		1307	for (qw(time signal child idle)) {
		1308	undef &{"AnyEvent::Base::$_"}
		1309	if defined &{"$MODEL\::$_"};
		1310	}
		1311
		1312	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1313
		1314	(shift @post_detect)->() while @post_detect;
		1315
		1316	*post_detect = sub(&) {
		1317	shift->();
		1318
		1319	undef
		1320	};
987		1321
988	$MODEL	1322	$MODEL
989	}	1323	}
990		1324
991	sub AUTOLOAD {	1325	sub AUTOLOAD {
992	(my $func = $AUTOLOAD) =~ s/.*://;	1326	(my $func = $AUTOLOAD) =~ s/.*://;
993		1327
994	$method{$func}	1328	$method{$func}
995	or croak "$func: not a valid method for AnyEvent objects";	1329	or Carp::croak "$func: not a valid AnyEvent class method";
996		1330
997	detect unless $MODEL;	1331	detect;
998		1332
999	my $class = shift;	1333	my $class = shift;
1000	$class->$func (@_);	1334	$class->$func (@_);
1001	}	1335	}
1002		1336
1003	# utility function to dup a filehandle. this is used by many backends	1337	# utility function to dup a filehandle. this is used by many backends
1004	# to support binding more than one watcher per filehandle (they usually	1338	# to support binding more than one watcher per filehandle (they usually
1005	# allow only one watcher per fd, so we dup it to get a different one).	1339	# allow only one watcher per fd, so we dup it to get a different one).
1006	sub _dupfh($$$$) {	1340	sub _dupfh($$;$$) {
1007	my ($poll, $fh, $r, $w) = @_;	1341	my ($poll, $fh, $r, $w) = @_;
1008		1342
1009	# cygwin requires the fh mode to be matching, unix doesn't	1343	# cygwin requires the fh mode to be matching, unix doesn't
1010	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1344	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1011	: $poll eq "w" ? ($w, ">")
1012	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1013		1345
1014	open my $fh2, "$mode&" . fileno $fh	1346	open my $fh2, $mode, $fh
1015	or die "cannot dup() filehandle: $!";	1347	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1016		1348
1017	# we assume CLOEXEC is already set by perl in all important cases	1349	# we assume CLOEXEC is already set by perl in all important cases
1018		1350
1019	($fh2, $rw)	1351	($fh2, $rw)
1020	}	1352	}
1021		1353
		1354	=head1 SIMPLIFIED AE API
		1355
		1356	Starting with version 5.0, AnyEvent officially supports a second, much
		1357	simpler, API that is designed to reduce the calling, typing and memory
		1358	overhead by using function call syntax and a fixed number of parameters.
		1359
		1360	See the L<AE> manpage for details.
		1361
		1362	=cut
		1363
		1364	package AE;
		1365
		1366	our $VERSION = $AnyEvent::VERSION;
		1367
		1368	# fall back to the main API by default - backends and AnyEvent::Base
		1369	# implementations can overwrite these.
		1370
		1371	sub io($$$) {
		1372	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1373	}
		1374
		1375	sub timer($$$) {
		1376	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1377	}
		1378
		1379	sub signal($$) {
		1380	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1381	}
		1382
		1383	sub child($$) {
		1384	AnyEvent->child (pid => $_[0], cb => $_[1])
		1385	}
		1386
		1387	sub idle($) {
		1388	AnyEvent->idle (cb => $_[0])
		1389	}
		1390
		1391	sub cv(;&) {
		1392	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1393	}
		1394
		1395	sub now() {
		1396	AnyEvent->now
		1397	}
		1398
		1399	sub now_update() {
		1400	AnyEvent->now_update
		1401	}
		1402
		1403	sub time() {
		1404	AnyEvent->time
		1405	}
		1406
1022	package AnyEvent::Base;	1407	package AnyEvent::Base;
1023		1408
1024	# default implementation for now and time	1409	# default implementations for many methods
1025		1410
1026	BEGIN {	1411	sub time {
		1412	eval q{ # poor man's autoloading {}
		1413	# probe for availability of Time::HiRes
1027	if (eval "use Time::HiRes (); time (); 1") {	1414	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1415	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1028	*_time = \&Time::HiRes::time;	1416	*AE::time = \&Time::HiRes::time;
1029	# if (eval "use POSIX (); (POSIX::times())...	1417	# if (eval "use POSIX (); (POSIX::times())...
1030	} else {	1418	} else {
		1419	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1031	*_time = sub { time }; # epic fail	1420	*AE::time = sub (){ time }; # epic fail
		1421	}
		1422
		1423	*time = sub { AE::time }; # different prototypes
		1424	};
		1425	die if $@;
		1426
		1427	&time
		1428	}
		1429
		1430	*now = \&time;
		1431
		1432	sub now_update { }
		1433
		1434	# default implementation for ->condvar
		1435
		1436	sub condvar {
		1437	eval q{ # poor man's autoloading {}
		1438	*condvar = sub {
		1439	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1440	};
		1441
		1442	*AE::cv = sub (;&) {
		1443	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1444	};
		1445	};
		1446	die if $@;
		1447
		1448	&condvar
		1449	}
		1450
		1451	# default implementation for ->signal
		1452
		1453	our $HAVE_ASYNC_INTERRUPT;
		1454
		1455	sub _have_async_interrupt() {
		1456	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1457	&& eval "use Async::Interrupt 1.02 (); 1")
		1458	unless defined $HAVE_ASYNC_INTERRUPT;
		1459
		1460	$HAVE_ASYNC_INTERRUPT
		1461	}
		1462
		1463	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1464	our (%SIG_ASY, %SIG_ASY_W);
		1465	our ($SIG_COUNT, $SIG_TW);
		1466
		1467	# install a dummy wakeup watcher to reduce signal catching latency
		1468	# used by Impls
		1469	sub _sig_add() {
		1470	unless ($SIG_COUNT++) {
		1471	# try to align timer on a full-second boundary, if possible
		1472	my $NOW = AE::now;
		1473
		1474	$SIG_TW = AE::timer
		1475	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1476	$MAX_SIGNAL_LATENCY,
		1477	sub { } # just for the PERL_ASYNC_CHECK
		1478	;
1032	}	1479	}
1033	}	1480	}
1034		1481
1035	sub time { _time }	1482	sub _sig_del {
1036	sub now { _time }	1483	undef $SIG_TW
1037		1484	unless --$SIG_COUNT;
1038	# default implementation for ->condvar
1039
1040	sub condvar {
1041	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
1042	}	1485	}
1043		1486
1044	# default implementation for ->signal	1487	our $_sig_name_init; $_sig_name_init = sub {
		1488	eval q{ # poor man's autoloading {}
		1489	undef $_sig_name_init;
1045		1490
1046	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1491	if (_have_async_interrupt) {
		1492	*sig2num = \&Async::Interrupt::sig2num;
		1493	*sig2name = \&Async::Interrupt::sig2name;
		1494	} else {
		1495	require Config;
1047		1496
1048	sub _signal_exec {	1497	my %signame2num;
1049	while (%SIG_EV) {	1498	@signame2num{ split ' ', $Config::Config{sig_name} }
1050	sysread $SIGPIPE_R, my $dummy, 4;	1499	= split ' ', $Config::Config{sig_num};
1051	for (keys %SIG_EV) {	1500
1052	delete $SIG_EV{$_};	1501	my @signum2name;
1053	$_->() for values %{ $SIG_CB{$_} || {} };	1502	@signum2name[values %signame2num] = keys %signame2num;
		1503
		1504	*sig2num = sub($) {
		1505	$_[0] > 0 ? shift : $signame2num{+shift}
		1506	};
		1507	*sig2name = sub ($) {
		1508	$_[0] > 0 ? $signum2name[+shift] : shift
		1509	};
1054	}	1510	}
1055	}	1511	};
1056	}	1512	die if $@;
		1513	};
		1514
		1515	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1516	sub sig2name($) { &$_sig_name_init; &sig2name }
1057		1517
1058	sub signal {	1518	sub signal {
1059	my (undef, %arg) = @_;	1519	eval q{ # poor man's autoloading {}
		1520	# probe for availability of Async::Interrupt
		1521	if (_have_async_interrupt) {
		1522	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1060		1523
1061	unless ($SIGPIPE_R) {	1524	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1062	if (AnyEvent::WIN32) {	1525	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1063	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();	1526
1064	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1065	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1066	} else {	1527	} else {
		1528	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1529
		1530	if (AnyEvent::WIN32) {
		1531	require AnyEvent::Util;
		1532
		1533	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1534	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1535	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1536	} else {
1067	pipe $SIGPIPE_R, $SIGPIPE_W;	1537	pipe $SIGPIPE_R, $SIGPIPE_W;
1068	require Fcntl;
1069	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1538	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1070	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1539	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1540
		1541	# not strictly required, as $^F is normally 2, but let's make sure...
		1542	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1543	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1544	}
		1545
		1546	$SIGPIPE_R
		1547	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1548
		1549	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1071	}	1550	}
1072		1551
1073	$SIGPIPE_R	1552	*signal = $HAVE_ASYNC_INTERRUPT
1074	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1553	? sub {
		1554	my (undef, %arg) = @_;
1075		1555
1076	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1556	# async::interrupt
1077	}
1078
1079	my $signal = uc $arg{signal}	1557	my $signal = sig2num $arg{signal};
1080	or Carp::croak "required option 'signal' is missing";
1081
1082	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1558	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1559
		1560	$SIG_ASY{$signal} ||= new Async::Interrupt
		1561	cb => sub { undef $SIG_EV{$signal} },
		1562	signal => $signal,
		1563	pipe => [$SIGPIPE_R->filenos],
		1564	pipe_autodrain => 0,
		1565	;
		1566
		1567	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1568	}
		1569	: sub {
		1570	my (undef, %arg) = @_;
		1571
		1572	# pure perl
		1573	my $signal = sig2name $arg{signal};
		1574	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1575
1083	$SIG{$signal} ||= sub {	1576	$SIG{$signal} ||= sub {
		1577	local $!;
1084	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1578	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1085	undef $SIG_EV{$signal};	1579	undef $SIG_EV{$signal};
		1580	};
		1581
		1582	# can't do signal processing without introducing races in pure perl,
		1583	# so limit the signal latency.
		1584	_sig_add;
		1585
		1586	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1587	}
		1588	;
		1589
		1590	*AnyEvent::Base::signal::DESTROY = sub {
		1591	my ($signal, $cb) = @{$_[0]};
		1592
		1593	_sig_del;
		1594
		1595	delete $SIG_CB{$signal}{$cb};
		1596
		1597	$HAVE_ASYNC_INTERRUPT
		1598	? delete $SIG_ASY{$signal}
		1599	: # delete doesn't work with older perls - they then
		1600	# print weird messages, or just unconditionally exit
		1601	# instead of getting the default action.
		1602	undef $SIG{$signal}
		1603	unless keys %{ $SIG_CB{$signal} };
		1604	};
		1605
		1606	*_signal_exec = sub {
		1607	$HAVE_ASYNC_INTERRUPT
		1608	? $SIGPIPE_R->drain
		1609	: sysread $SIGPIPE_R, (my $dummy), 9;
		1610
		1611	while (%SIG_EV) {
		1612	for (keys %SIG_EV) {
		1613	delete $SIG_EV{$_};
		1614	$_->() for values %{ $SIG_CB{$_} || {} };
		1615	}
		1616	}
		1617	};
1086	};	1618	};
		1619	die if $@;
1087		1620
1088	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1621	&signal
1089	}
1090
1091	sub AnyEvent::Base::Signal::DESTROY {
1092	my ($signal, $cb) = @{$_[0]};
1093
1094	delete $SIG_CB{$signal}{$cb};
1095
1096	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1097	}	1622	}
1098		1623
1099	# default implementation for ->child	1624	# default implementation for ->child
1100		1625
1101	our %PID_CB;	1626	our %PID_CB;
1102	our $CHLD_W;	1627	our $CHLD_W;
1103	our $CHLD_DELAY_W;	1628	our $CHLD_DELAY_W;
1104	our $PID_IDLE;
1105	our $WNOHANG;	1629	our $WNOHANG;
1106		1630
1107	sub _child_wait {	1631	# used by many Impl's
1108	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1632	sub _emit_childstatus($$) {
		1633	my (undef, $rpid, $rstatus) = @_;
		1634
		1635	$_->($rpid, $rstatus)
1109	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1636	for values %{ $PID_CB{$rpid} || {} },
1110	(values %{ $PID_CB{0} || {} });	1637	values %{ $PID_CB{0} || {} };
1111	}
1112
1113	undef $PID_IDLE;
1114	}
1115
1116	sub _sigchld {
1117	# make sure we deliver these changes "synchronous" with the event loop.
1118	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1119	undef $CHLD_DELAY_W;
1120	&_child_wait;
1121	});
1122	}	1638	}
1123		1639
1124	sub child {	1640	sub child {
		1641	eval q{ # poor man's autoloading {}
		1642	*_sigchld = sub {
		1643	my $pid;
		1644
		1645	AnyEvent->_emit_childstatus ($pid, $?)
		1646	while ($pid = waitpid -1, $WNOHANG) > 0;
		1647	};
		1648
		1649	*child = sub {
1125	my (undef, %arg) = @_;	1650	my (undef, %arg) = @_;
1126		1651
1127	defined (my $pid = $arg{pid} + 0)	1652	defined (my $pid = $arg{pid} + 0)
1128	or Carp::croak "required option 'pid' is missing";	1653	or Carp::croak "required option 'pid' is missing";
1129		1654
1130	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1655	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1131		1656
1132	unless ($WNOHANG) {	1657	# WNOHANG is almost cetrainly 1 everywhere
		1658	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1659	? 1
1133	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1660	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1134	}
1135		1661
1136	unless ($CHLD_W) {	1662	unless ($CHLD_W) {
1137	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1663	$CHLD_W = AE::signal CHLD => \&_sigchld;
1138	# child could be a zombie already, so make at least one round	1664	# child could be a zombie already, so make at least one round
1139	&_sigchld;	1665	&_sigchld;
1140	}	1666	}
1141		1667
1142	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1668	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1143	}	1669	};
1144		1670
1145	sub AnyEvent::Base::Child::DESTROY {	1671	*AnyEvent::Base::child::DESTROY = sub {
1146	my ($pid, $cb) = @{$_[0]};	1672	my ($pid, $cb) = @{$_[0]};
1147		1673
1148	delete $PID_CB{$pid}{$cb};	1674	delete $PID_CB{$pid}{$cb};
1149	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1675	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1150		1676
1151	undef $CHLD_W unless keys %PID_CB;	1677	undef $CHLD_W unless keys %PID_CB;
		1678	};
		1679	};
		1680	die if $@;
		1681
		1682	&child
		1683	}
		1684
		1685	# idle emulation is done by simply using a timer, regardless
		1686	# of whether the process is idle or not, and not letting
		1687	# the callback use more than 50% of the time.
		1688	sub idle {
		1689	eval q{ # poor man's autoloading {}
		1690	*idle = sub {
		1691	my (undef, %arg) = @_;
		1692
		1693	my ($cb, $w, $rcb) = $arg{cb};
		1694
		1695	$rcb = sub {
		1696	if ($cb) {
		1697	$w = _time;
		1698	&$cb;
		1699	$w = _time - $w;
		1700
		1701	# never use more then 50% of the time for the idle watcher,
		1702	# within some limits
		1703	$w = 0.0001 if $w < 0.0001;
		1704	$w = 5 if $w > 5;
		1705
		1706	$w = AE::timer $w, 0, $rcb;
		1707	} else {
		1708	# clean up...
		1709	undef $w;
		1710	undef $rcb;
		1711	}
		1712	};
		1713
		1714	$w = AE::timer 0.05, 0, $rcb;
		1715
		1716	bless \\$cb, "AnyEvent::Base::idle"
		1717	};
		1718
		1719	*AnyEvent::Base::idle::DESTROY = sub {
		1720	undef $${$_[0]};
		1721	};
		1722	};
		1723	die if $@;
		1724
		1725	&idle
1152	}	1726	}
1153		1727
1154	package AnyEvent::CondVar;	1728	package AnyEvent::CondVar;
1155		1729
1156	our @ISA = AnyEvent::CondVar::Base::;	1730	our @ISA = AnyEvent::CondVar::Base::;
1157		1731
		1732	# only to be used for subclassing
		1733	sub new {
		1734	my $class = shift;
		1735	bless AnyEvent->condvar (@_), $class
		1736	}
		1737
1158	package AnyEvent::CondVar::Base;	1738	package AnyEvent::CondVar::Base;
1159		1739
1160	use overload	1740	#use overload
1161	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1741	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1162	fallback => 1;	1742	# fallback => 1;
		1743
		1744	# save 300+ kilobytes by dirtily hardcoding overloading
		1745	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1746	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1747	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1748	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1749
		1750	our $WAITING;
1163		1751
1164	sub _send {	1752	sub _send {
1165	# nop	1753	# nop
1166	}	1754	}
1167		1755
…		…
1180	sub ready {	1768	sub ready {
1181	$_[0]{_ae_sent}	1769	$_[0]{_ae_sent}
1182	}	1770	}
1183		1771
1184	sub _wait {	1772	sub _wait {
		1773	$WAITING
		1774	and !$_[0]{_ae_sent}
		1775	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1776
		1777	local $WAITING = 1;
1185	AnyEvent->one_event while !$_[0]{_ae_sent};	1778	AnyEvent->one_event while !$_[0]{_ae_sent};
1186	}	1779	}
1187		1780
1188	sub recv {	1781	sub recv {
1189	$_[0]->_wait;	1782	$_[0]->_wait;
…		…
1191	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1784	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1192	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1785	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1193	}	1786	}
1194		1787
1195	sub cb {	1788	sub cb {
1196	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1789	my $cv = shift;
		1790
		1791	@_
		1792	and $cv->{_ae_cb} = shift
		1793	and $cv->{_ae_sent}
		1794	and (delete $cv->{_ae_cb})->($cv);
		1795
1197	$_[0]{_ae_cb}	1796	$cv->{_ae_cb}
1198	}	1797	}
1199		1798
1200	sub begin {	1799	sub begin {
1201	++$_[0]{_ae_counter};	1800	++$_[0]{_ae_counter};
1202	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1801	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1230	so on.	1829	so on.
1231		1830
1232	=head1 ENVIRONMENT VARIABLES	1831	=head1 ENVIRONMENT VARIABLES
1233		1832
1234	The following environment variables are used by this module or its	1833	The following environment variables are used by this module or its
1235	submodules:	1834	submodules.
		1835
		1836	Note that AnyEvent will remove I<all> environment variables starting with
		1837	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1838	enabled.
1236		1839
1237	=over 4	1840	=over 4
1238		1841
1239	=item C<PERL_ANYEVENT_VERBOSE>	1842	=item C<PERL_ANYEVENT_VERBOSE>
1240		1843
…		…
1247	C<PERL_ANYEVENT_MODEL>.	1850	C<PERL_ANYEVENT_MODEL>.
1248		1851
1249	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1852	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1250	model it chooses.	1853	model it chooses.
1251		1854
		1855	When set to C<8> or higher, then AnyEvent will report extra information on
		1856	which optional modules it loads and how it implements certain features.
		1857
1252	=item C<PERL_ANYEVENT_STRICT>	1858	=item C<PERL_ANYEVENT_STRICT>
1253		1859
1254	AnyEvent does not do much argument checking by default, as thorough	1860	AnyEvent does not do much argument checking by default, as thorough
1255	argument checking is very costly. Setting this variable to a true value	1861	argument checking is very costly. Setting this variable to a true value
1256	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1862	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1257	check the arguments passed to most method calls. If it finds any problems	1863	check the arguments passed to most method calls. If it finds any problems,
1258	it will croak.	1864	it will croak.
1259		1865
1260	In other words, enables "strict" mode.	1866	In other words, enables "strict" mode.
1261		1867
1262	Unlike C<use strict>, it is definitely recommended ot keep it off in	1868	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1263	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1869	>>, it is definitely recommended to keep it off in production. Keeping
1264	developing programs can be very useful, however.	1870	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1871	can be very useful, however.
1265		1872
1266	=item C<PERL_ANYEVENT_MODEL>	1873	=item C<PERL_ANYEVENT_MODEL>
1267		1874
1268	This can be used to specify the event model to be used by AnyEvent, before	1875	This can be used to specify the event model to be used by AnyEvent, before
1269	auto detection and -probing kicks in. It must be a string consisting	1876	auto detection and -probing kicks in. It must be a string consisting
…		…
1312		1919
1313	=item C<PERL_ANYEVENT_MAX_FORKS>	1920	=item C<PERL_ANYEVENT_MAX_FORKS>
1314		1921
1315	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1922	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1316	will create in parallel.	1923	will create in parallel.
		1924
		1925	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1926
		1927	The default value for the C<max_outstanding> parameter for the default DNS
		1928	resolver - this is the maximum number of parallel DNS requests that are
		1929	sent to the DNS server.
		1930
		1931	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1932
		1933	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1934	configuration) in the default resolver. When set to the empty string, no
		1935	default config will be used.
		1936
		1937	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1938
		1939	When neither C<ca_file> nor C<ca_path> was specified during
		1940	L<AnyEvent::TLS> context creation, and either of these environment
		1941	variables exist, they will be used to specify CA certificate locations
		1942	instead of a system-dependent default.
		1943
		1944	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1945
		1946	When these are set to C<1>, then the respective modules are not
		1947	loaded. Mostly good for testing AnyEvent itself.
1317		1948
1318	=back	1949	=back
1319		1950
1320	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1951	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1321		1952
…		…
1379	warn "read: $input\n"; # output what has been read	2010	warn "read: $input\n"; # output what has been read
1380	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2011	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1381	},	2012	},
1382	);	2013	);
1383		2014
1384	my $time_watcher; # can only be used once
1385
1386	sub new_timer {
1387	$timer = AnyEvent->timer (after => 1, cb => sub {	2015	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1388	warn "timeout\n"; # print 'timeout' about every second	2016	warn "timeout\n"; # print 'timeout' at most every second
1389	&new_timer; # and restart the time
1390	});	2017	});
1391	}
1392
1393	new_timer; # create first timer
1394		2018
1395	$cv->recv; # wait until user enters /^q/i	2019	$cv->recv; # wait until user enters /^q/i
1396		2020
1397	=head1 REAL-WORLD EXAMPLE	2021	=head1 REAL-WORLD EXAMPLE
1398		2022
…		…
1471		2095
1472	The actual code goes further and collects all errors (C<die>s, exceptions)	2096	The actual code goes further and collects all errors (C<die>s, exceptions)
1473	that occurred during request processing. The C<result> method detects	2097	that occurred during request processing. The C<result> method detects
1474	whether an exception as thrown (it is stored inside the $txn object)	2098	whether an exception as thrown (it is stored inside the $txn object)
1475	and just throws the exception, which means connection errors and other	2099	and just throws the exception, which means connection errors and other
1476	problems get reported tot he code that tries to use the result, not in a	2100	problems get reported to the code that tries to use the result, not in a
1477	random callback.	2101	random callback.
1478		2102
1479	All of this enables the following usage styles:	2103	All of this enables the following usage styles:
1480		2104
1481	1. Blocking:	2105	1. Blocking:
…		…
1529	through AnyEvent. The benchmark creates a lot of timers (with a zero	2153	through AnyEvent. The benchmark creates a lot of timers (with a zero
1530	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2154	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1531	which it is), lets them fire exactly once and destroys them again.	2155	which it is), lets them fire exactly once and destroys them again.
1532		2156
1533	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2157	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1534	distribution.	2158	distribution. It uses the L<AE> interface, which makes a real difference
		2159	for the EV and Perl backends only.
1535		2160
1536	=head3 Explanation of the columns	2161	=head3 Explanation of the columns
1537		2162
1538	I<watcher> is the number of event watchers created/destroyed. Since	2163	I<watcher> is the number of event watchers created/destroyed. Since
1539	different event models feature vastly different performances, each event	2164	different event models feature vastly different performances, each event
…		…
1560	watcher.	2185	watcher.
1561		2186
1562	=head3 Results	2187	=head3 Results
1563		2188
1564	name watchers bytes create invoke destroy comment	2189	name watchers bytes create invoke destroy comment
1565	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2190	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1566	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2191	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1567	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2192	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1568	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2193	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1569	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2194	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1570	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2195	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2196	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2197	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1571	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2198	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1572	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2199	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1573	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2200	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1574	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2201	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1575		2202
1576	=head3 Discussion	2203	=head3 Discussion
1577		2204
1578	The benchmark does I<not> measure scalability of the event loop very	2205	The benchmark does I<not> measure scalability of the event loop very
1579	well. For example, a select-based event loop (such as the pure perl one)	2206	well. For example, a select-based event loop (such as the pure perl one)
…		…
1591	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2218	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1592	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2219	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1593	cycles with POE.	2220	cycles with POE.
1594		2221
1595	C<EV> is the sole leader regarding speed and memory use, which are both	2222	C<EV> is the sole leader regarding speed and memory use, which are both
1596	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2223	maximal/minimal, respectively. When using the L<AE> API there is zero
		2224	overhead (when going through the AnyEvent API create is about 5-6 times
		2225	slower, with other times being equal, so still uses far less memory than
1597	far less memory than any other event loop and is still faster than Event	2226	any other event loop and is still faster than Event natively).
1598	natively.
1599		2227
1600	The pure perl implementation is hit in a few sweet spots (both the	2228	The pure perl implementation is hit in a few sweet spots (both the
1601	constant timeout and the use of a single fd hit optimisations in the perl	2229	constant timeout and the use of a single fd hit optimisations in the perl
1602	interpreter and the backend itself). Nevertheless this shows that it	2230	interpreter and the backend itself). Nevertheless this shows that it
1603	adds very little overhead in itself. Like any select-based backend its	2231	adds very little overhead in itself. Like any select-based backend its
1604	performance becomes really bad with lots of file descriptors (and few of	2232	performance becomes really bad with lots of file descriptors (and few of
1605	them active), of course, but this was not subject of this benchmark.	2233	them active), of course, but this was not subject of this benchmark.
1606		2234
1607	The C<Event> module has a relatively high setup and callback invocation	2235	The C<Event> module has a relatively high setup and callback invocation
1608	cost, but overall scores in on the third place.	2236	cost, but overall scores in on the third place.
		2237
		2238	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2239	when using its pure perl backend.
1609		2240
1610	C<Glib>'s memory usage is quite a bit higher, but it features a	2241	C<Glib>'s memory usage is quite a bit higher, but it features a
1611	faster callback invocation and overall ends up in the same class as	2242	faster callback invocation and overall ends up in the same class as
1612	C<Event>. However, Glib scales extremely badly, doubling the number of	2243	C<Event>. However, Glib scales extremely badly, doubling the number of
1613	watchers increases the processing time by more than a factor of four,	2244	watchers increases the processing time by more than a factor of four,
…		…
1674	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2305	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1675	(1%) are active. This mirrors the activity of large servers with many	2306	(1%) are active. This mirrors the activity of large servers with many
1676	connections, most of which are idle at any one point in time.	2307	connections, most of which are idle at any one point in time.
1677		2308
1678	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2309	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1679	distribution.	2310	distribution. It uses the L<AE> interface, which makes a real difference
		2311	for the EV and Perl backends only.
1680		2312
1681	=head3 Explanation of the columns	2313	=head3 Explanation of the columns
1682		2314
1683	I<sockets> is the number of sockets, and twice the number of "servers" (as	2315	I<sockets> is the number of sockets, and twice the number of "servers" (as
1684	each server has a read and write socket end).	2316	each server has a read and write socket end).
…		…
1691	it to another server. This includes deleting the old timeout and creating	2323	it to another server. This includes deleting the old timeout and creating
1692	a new one that moves the timeout into the future.	2324	a new one that moves the timeout into the future.
1693		2325
1694	=head3 Results	2326	=head3 Results
1695		2327
1696	name sockets create request	2328	name sockets create request
1697	EV 20000 69.01 11.16	2329	EV 20000 62.66 7.99
1698	Perl 20000 73.32 35.87	2330	Perl 20000 68.32 32.64
1699	Event 20000 212.62 257.32	2331	IOAsync 20000 174.06 101.15 epoll
1700	Glib 20000 651.16 1896.30	2332	IOAsync 20000 174.67 610.84 poll
		2333	Event 20000 202.69 242.91
		2334	Glib 20000 557.01 1689.52
1701	POE 20000 349.67 12317.24 uses POE::Loop::Event	2335	POE 20000 341.54 12086.32 uses POE::Loop::Event
1702		2336
1703	=head3 Discussion	2337	=head3 Discussion
1704		2338
1705	This benchmark I<does> measure scalability and overall performance of the	2339	This benchmark I<does> measure scalability and overall performance of the
1706	particular event loop.	2340	particular event loop.
…		…
1708	EV is again fastest. Since it is using epoll on my system, the setup time	2342	EV is again fastest. Since it is using epoll on my system, the setup time
1709	is relatively high, though.	2343	is relatively high, though.
1710		2344
1711	Perl surprisingly comes second. It is much faster than the C-based event	2345	Perl surprisingly comes second. It is much faster than the C-based event
1712	loops Event and Glib.	2346	loops Event and Glib.
		2347
		2348	IO::Async performs very well when using its epoll backend, and still quite
		2349	good compared to Glib when using its pure perl backend.
1713		2350
1714	Event suffers from high setup time as well (look at its code and you will	2351	Event suffers from high setup time as well (look at its code and you will
1715	understand why). Callback invocation also has a high overhead compared to	2352	understand why). Callback invocation also has a high overhead compared to
1716	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2353	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1717	uses select or poll in basically all documented configurations.	2354	uses select or poll in basically all documented configurations.
…		…
1780	=item * C-based event loops perform very well with small number of	2417	=item * C-based event loops perform very well with small number of
1781	watchers, as the management overhead dominates.	2418	watchers, as the management overhead dominates.
1782		2419
1783	=back	2420	=back
1784		2421
		2422	=head2 THE IO::Lambda BENCHMARK
		2423
		2424	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2425	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2426	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2427	shouldn't come as a surprise to anybody). As such, the benchmark is
		2428	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2429	very optimal. But how would AnyEvent compare when used without the extra
		2430	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2431
		2432	The benchmark itself creates an echo-server, and then, for 500 times,
		2433	connects to the echo server, sends a line, waits for the reply, and then
		2434	creates the next connection. This is a rather bad benchmark, as it doesn't
		2435	test the efficiency of the framework or much non-blocking I/O, but it is a
		2436	benchmark nevertheless.
		2437
		2438	name runtime
		2439	Lambda/select 0.330 sec
		2440	+ optimized 0.122 sec
		2441	Lambda/AnyEvent 0.327 sec
		2442	+ optimized 0.138 sec
		2443	Raw sockets/select 0.077 sec
		2444	POE/select, components 0.662 sec
		2445	POE/select, raw sockets 0.226 sec
		2446	POE/select, optimized 0.404 sec
		2447
		2448	AnyEvent/select/nb 0.085 sec
		2449	AnyEvent/EV/nb 0.068 sec
		2450	+state machine 0.134 sec
		2451
		2452	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2453	benchmarks actually make blocking connects and use 100% blocking I/O,
		2454	defeating the purpose of an event-based solution. All of the newly
		2455	written AnyEvent benchmarks use 100% non-blocking connects (using
		2456	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2457	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2458	generally require a lot more bookkeeping and event handling than blocking
		2459	connects (which involve a single syscall only).
		2460
		2461	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2462	offers similar expressive power as POE and IO::Lambda, using conventional
		2463	Perl syntax. This means that both the echo server and the client are 100%
		2464	non-blocking, further placing it at a disadvantage.
		2465
		2466	As you can see, the AnyEvent + EV combination even beats the
		2467	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2468	backend easily beats IO::Lambda and POE.
		2469
		2470	And even the 100% non-blocking version written using the high-level (and
		2471	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2472	higher level ("unoptimised") abstractions by a large margin, even though
		2473	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2474
		2475	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2476	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2477	part of the IO::Lambda distribution and were used without any changes.
		2478
1785		2479
1786	=head1 SIGNALS	2480	=head1 SIGNALS
1787		2481
1788	AnyEvent currently installs handlers for these signals:	2482	AnyEvent currently installs handlers for these signals:
1789		2483
…		…
1792	=item SIGCHLD	2486	=item SIGCHLD
1793		2487
1794	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2488	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1795	emulation for event loops that do not support them natively. Also, some	2489	emulation for event loops that do not support them natively. Also, some
1796	event loops install a similar handler.	2490	event loops install a similar handler.
		2491
		2492	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2493	AnyEvent will reset it to default, to avoid losing child exit statuses.
1797		2494
1798	=item SIGPIPE	2495	=item SIGPIPE
1799		2496
1800	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2497	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1801	when AnyEvent gets loaded.	2498	when AnyEvent gets loaded.
…		…
1813		2510
1814	=back	2511	=back
1815		2512
1816	=cut	2513	=cut
1817		2514
		2515	undef $SIG{CHLD}
		2516	if $SIG{CHLD} eq 'IGNORE';
		2517
1818	$SIG{PIPE} = sub { }	2518	$SIG{PIPE} = sub { }
1819	unless defined $SIG{PIPE};	2519	unless defined $SIG{PIPE};
1820		2520
		2521	=head1 RECOMMENDED/OPTIONAL MODULES
		2522
		2523	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2524	its built-in modules) are required to use it.
		2525
		2526	That does not mean that AnyEvent won't take advantage of some additional
		2527	modules if they are installed.
		2528
		2529	This section explains which additional modules will be used, and how they
		2530	affect AnyEvent's operation.
		2531
		2532	=over 4
		2533
		2534	=item L<Async::Interrupt>
		2535
		2536	This slightly arcane module is used to implement fast signal handling: To
		2537	my knowledge, there is no way to do completely race-free and quick
		2538	signal handling in pure perl. To ensure that signals still get
		2539	delivered, AnyEvent will start an interval timer to wake up perl (and
		2540	catch the signals) with some delay (default is 10 seconds, look for
		2541	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2542
		2543	If this module is available, then it will be used to implement signal
		2544	catching, which means that signals will not be delayed, and the event loop
		2545	will not be interrupted regularly, which is more efficient (and good for
		2546	battery life on laptops).
		2547
		2548	This affects not just the pure-perl event loop, but also other event loops
		2549	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2550
		2551	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2552	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2553	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2554	does nothing for those backends.
		2555
		2556	=item L<EV>
		2557
		2558	This module isn't really "optional", as it is simply one of the backend
		2559	event loops that AnyEvent can use. However, it is simply the best event
		2560	loop available in terms of features, speed and stability: It supports
		2561	the AnyEvent API optimally, implements all the watcher types in XS, does
		2562	automatic timer adjustments even when no monotonic clock is available,
		2563	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2564	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2565	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2566
		2567	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2568	then this module will do nothing for you.
		2569
		2570	=item L<Guard>
		2571
		2572	The guard module, when used, will be used to implement
		2573	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2574	lot less memory), but otherwise doesn't affect guard operation much. It is
		2575	purely used for performance.
		2576
		2577	=item L<JSON> and L<JSON::XS>
		2578
		2579	One of these modules is required when you want to read or write JSON data
		2580	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2581	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2582
		2583	=item L<Net::SSLeay>
		2584
		2585	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2586	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2587	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2588
		2589	=item L<Time::HiRes>
		2590
		2591	This module is part of perl since release 5.008. It will be used when the
		2592	chosen event library does not come with a timing source of its own. The
		2593	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2594	try to use a monotonic clock for timing stability.
		2595
		2596	=back
		2597
1821		2598
1822	=head1 FORK	2599	=head1 FORK
1823		2600
1824	Most event libraries are not fork-safe. The ones who are usually are	2601	Most event libraries are not fork-safe. The ones who are usually are
1825	because they rely on inefficient but fork-safe C<select> or C<poll>	2602	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1826	calls. Only L<EV> is fully fork-aware.	2603	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2604	are usually badly thought-out hacks that are incompatible with fork in
		2605	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2606	continue event-processing in both parent and child (or both, if you know
		2607	what you are doing).
		2608
		2609	This means that, in general, you cannot fork and do event processing in
		2610	the child if the event library was initialised before the fork (which
		2611	usually happens when the first AnyEvent watcher is created, or the library
		2612	is loaded).
1827		2613
1828	If you have to fork, you must either do so I<before> creating your first	2614	If you have to fork, you must either do so I<before> creating your first
1829	watcher OR you must not use AnyEvent at all in the child.	2615	watcher OR you must not use AnyEvent at all in the child OR you must do
		2616	something completely out of the scope of AnyEvent.
		2617
		2618	The problem of doing event processing in the parent I<and> the child
		2619	is much more complicated: even for backends that I<are> fork-aware or
		2620	fork-safe, their behaviour is not usually what you want: fork clones all
		2621	watchers, that means all timers, I/O watchers etc. are active in both
		2622	parent and child, which is almost never what you want. USing C<exec>
		2623	to start worker children from some kind of manage rprocess is usually
		2624	preferred, because it is much easier and cleaner, at the expense of having
		2625	to have another binary.
1830		2626
1831		2627
1832	=head1 SECURITY CONSIDERATIONS	2628	=head1 SECURITY CONSIDERATIONS
1833		2629
1834	AnyEvent can be forced to load any event model via	2630	AnyEvent can be forced to load any event model via
…		…
1846	use AnyEvent;	2642	use AnyEvent;
1847		2643
1848	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2644	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1849	be used to probe what backend is used and gain other information (which is	2645	be used to probe what backend is used and gain other information (which is
1850	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2646	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1851	$ENV{PERL_ANYEGENT_STRICT}.	2647	$ENV{PERL_ANYEVENT_STRICT}.
		2648
		2649	Note that AnyEvent will remove I<all> environment variables starting with
		2650	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2651	enabled.
1852		2652
1853		2653
1854	=head1 BUGS	2654	=head1 BUGS
1855		2655
1856	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2656	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1857	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2657	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1858	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2658	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1859	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2659	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1860	pronounced).	2660	pronounced).
1861		2661
1862		2662
1863	=head1 SEE ALSO	2663	=head1 SEE ALSO
		2664
		2665	Tutorial/Introduction: L<AnyEvent::Intro>.
		2666
		2667	FAQ: L<AnyEvent::FAQ>.
1864		2668
1865	Utility functions: L<AnyEvent::Util>.	2669	Utility functions: L<AnyEvent::Util>.
1866		2670
1867	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2671	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1868	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2672	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1869		2673
1870	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2674	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1871	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2675	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1872	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2676	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1873	L<AnyEvent::Impl::POE>.	2677	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1874		2678
1875	Non-blocking file handles, sockets, TCP clients and	2679	Non-blocking file handles, sockets, TCP clients and
1876	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2680	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1877		2681
1878	Asynchronous DNS: L<AnyEvent::DNS>.	2682	Asynchronous DNS: L<AnyEvent::DNS>.
1879		2683
1880	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2684	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1881		2685
1882	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2686	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2687	L<AnyEvent::HTTP>.
1883		2688
1884		2689
1885	=head1 AUTHOR	2690	=head1 AUTHOR
1886		2691
1887	Marc Lehmann <schmorp@schmorp.de>	2692	Marc Lehmann <schmorp@schmorp.de>

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