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Revision 1.340 by root, Fri Dec 3 18:39:06 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<Net::IRC3>
831
832	AnyEvent based IRC client module family.
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 = 4.3;	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	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1313	eval { require AnyEvent::Strict };
		1314	warn "AnyEvent: cannot load AnyEvent::Strict: $@"
		1315	if $@ && $VERBOSE;
		1316	}
		1317
		1318	(shift @post_detect)->() while @post_detect;
		1319
		1320	*post_detect = sub(&) {
		1321	shift->();
		1322
		1323	undef
		1324	};
987		1325
988	$MODEL	1326	$MODEL
989	}	1327	}
990		1328
991	sub AUTOLOAD {	1329	sub AUTOLOAD {
992	(my $func = $AUTOLOAD) =~ s/.*://;	1330	(my $func = $AUTOLOAD) =~ s/.*://;
993		1331
994	$method{$func}	1332	$method{$func}
995	or croak "$func: not a valid method for AnyEvent objects";	1333	or Carp::croak "$func: not a valid AnyEvent class method";
996		1334
997	detect unless $MODEL;	1335	detect;
998		1336
999	my $class = shift;	1337	my $class = shift;
1000	$class->$func (@_);	1338	$class->$func (@_);
1001	}	1339	}
1002		1340
1003	# utility function to dup a filehandle. this is used by many backends	1341	# utility function to dup a filehandle. this is used by many backends
1004	# to support binding more than one watcher per filehandle (they usually	1342	# 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).	1343	# allow only one watcher per fd, so we dup it to get a different one).
1006	sub _dupfh($$$$) {	1344	sub _dupfh($$;$$) {
1007	my ($poll, $fh, $r, $w) = @_;	1345	my ($poll, $fh, $r, $w) = @_;
1008		1346
1009	require Fcntl;
1010
1011	# cygwin requires the fh mode to be matching, unix doesn't	1347	# cygwin requires the fh mode to be matching, unix doesn't
1012	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1348	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1013	: $poll eq "w" ? ($w, ">")
1014	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1015		1349
1016	open my $fh2, "$mode&" . fileno $fh	1350	open my $fh2, $mode, $fh
1017	or die "cannot dup() filehandle: $!";	1351	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1018		1352
1019	# we assume CLOEXEC is already set by perl in all important cases	1353	# we assume CLOEXEC is already set by perl in all important cases
1020		1354
1021	($fh2, $rw)	1355	($fh2, $rw)
1022	}	1356	}
1023		1357
		1358	=head1 SIMPLIFIED AE API
		1359
		1360	Starting with version 5.0, AnyEvent officially supports a second, much
		1361	simpler, API that is designed to reduce the calling, typing and memory
		1362	overhead by using function call syntax and a fixed number of parameters.
		1363
		1364	See the L<AE> manpage for details.
		1365
		1366	=cut
		1367
		1368	package AE;
		1369
		1370	our $VERSION = $AnyEvent::VERSION;
		1371
		1372	# fall back to the main API by default - backends and AnyEvent::Base
		1373	# implementations can overwrite these.
		1374
		1375	sub io($$$) {
		1376	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1377	}
		1378
		1379	sub timer($$$) {
		1380	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1381	}
		1382
		1383	sub signal($$) {
		1384	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1385	}
		1386
		1387	sub child($$) {
		1388	AnyEvent->child (pid => $_[0], cb => $_[1])
		1389	}
		1390
		1391	sub idle($) {
		1392	AnyEvent->idle (cb => $_[0])
		1393	}
		1394
		1395	sub cv(;&) {
		1396	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1397	}
		1398
		1399	sub now() {
		1400	AnyEvent->now
		1401	}
		1402
		1403	sub now_update() {
		1404	AnyEvent->now_update
		1405	}
		1406
		1407	sub time() {
		1408	AnyEvent->time
		1409	}
		1410
1024	package AnyEvent::Base;	1411	package AnyEvent::Base;
1025		1412
1026	# default implementation for now and time	1413	# default implementations for many methods
1027		1414
1028	BEGIN {	1415	sub time {
		1416	eval q{ # poor man's autoloading {}
		1417	# probe for availability of Time::HiRes
1029	if (eval "use Time::HiRes (); time (); 1") {	1418	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1419	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1030	*_time = \&Time::HiRes::time;	1420	*AE::time = \&Time::HiRes::time;
1031	# if (eval "use POSIX (); (POSIX::times())...	1421	# if (eval "use POSIX (); (POSIX::times())...
1032	} else {	1422	} else {
		1423	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1033	*_time = sub { time }; # epic fail	1424	*AE::time = sub (){ time }; # epic fail
		1425	}
		1426
		1427	*time = sub { AE::time }; # different prototypes
		1428	};
		1429	die if $@;
		1430
		1431	&time
		1432	}
		1433
		1434	*now = \&time;
		1435
		1436	sub now_update { }
		1437
		1438	# default implementation for ->condvar
		1439
		1440	sub condvar {
		1441	eval q{ # poor man's autoloading {}
		1442	*condvar = sub {
		1443	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1444	};
		1445
		1446	*AE::cv = sub (;&) {
		1447	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1448	};
		1449	};
		1450	die if $@;
		1451
		1452	&condvar
		1453	}
		1454
		1455	# default implementation for ->signal
		1456
		1457	our $HAVE_ASYNC_INTERRUPT;
		1458
		1459	sub _have_async_interrupt() {
		1460	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1461	&& eval "use Async::Interrupt 1.02 (); 1")
		1462	unless defined $HAVE_ASYNC_INTERRUPT;
		1463
		1464	$HAVE_ASYNC_INTERRUPT
		1465	}
		1466
		1467	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1468	our (%SIG_ASY, %SIG_ASY_W);
		1469	our ($SIG_COUNT, $SIG_TW);
		1470
		1471	# install a dummy wakeup watcher to reduce signal catching latency
		1472	# used by Impls
		1473	sub _sig_add() {
		1474	unless ($SIG_COUNT++) {
		1475	# try to align timer on a full-second boundary, if possible
		1476	my $NOW = AE::now;
		1477
		1478	$SIG_TW = AE::timer
		1479	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1480	$MAX_SIGNAL_LATENCY,
		1481	sub { } # just for the PERL_ASYNC_CHECK
		1482	;
1034	}	1483	}
1035	}	1484	}
1036		1485
1037	sub time { _time }	1486	sub _sig_del {
1038	sub now { _time }	1487	undef $SIG_TW
1039		1488	unless --$SIG_COUNT;
1040	# default implementation for ->condvar
1041
1042	sub condvar {
1043	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
1044	}	1489	}
1045		1490
1046	# default implementation for ->signal	1491	our $_sig_name_init; $_sig_name_init = sub {
		1492	eval q{ # poor man's autoloading {}
		1493	undef $_sig_name_init;
1047		1494
1048	our %SIG_CB;	1495	if (_have_async_interrupt) {
		1496	*sig2num = \&Async::Interrupt::sig2num;
		1497	*sig2name = \&Async::Interrupt::sig2name;
		1498	} else {
		1499	require Config;
		1500
		1501	my %signame2num;
		1502	@signame2num{ split ' ', $Config::Config{sig_name} }
		1503	= split ' ', $Config::Config{sig_num};
		1504
		1505	my @signum2name;
		1506	@signum2name[values %signame2num] = keys %signame2num;
		1507
		1508	*sig2num = sub($) {
		1509	$_[0] > 0 ? shift : $signame2num{+shift}
		1510	};
		1511	*sig2name = sub ($) {
		1512	$_[0] > 0 ? $signum2name[+shift] : shift
		1513	};
		1514	}
		1515	};
		1516	die if $@;
		1517	};
		1518
		1519	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1520	sub sig2name($) { &$_sig_name_init; &sig2name }
1049		1521
1050	sub signal {	1522	sub signal {
		1523	eval q{ # poor man's autoloading {}
		1524	# probe for availability of Async::Interrupt
		1525	if (_have_async_interrupt) {
		1526	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1527
		1528	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1529	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1530
		1531	} else {
		1532	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1533
		1534	if (AnyEvent::WIN32) {
		1535	require AnyEvent::Util;
		1536
		1537	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1538	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1539	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1540	} else {
		1541	pipe $SIGPIPE_R, $SIGPIPE_W;
		1542	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1543	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1544
		1545	# not strictly required, as $^F is normally 2, but let's make sure...
		1546	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1547	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1548	}
		1549
		1550	$SIGPIPE_R
		1551	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1552
		1553	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1554	}
		1555
		1556	*signal = $HAVE_ASYNC_INTERRUPT
		1557	? sub {
1051	my (undef, %arg) = @_;	1558	my (undef, %arg) = @_;
1052		1559
		1560	# async::interrupt
1053	my $signal = uc $arg{signal}	1561	my $signal = sig2num $arg{signal};
1054	or Carp::croak "required option 'signal' is missing";
1055
1056	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1562	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1563
		1564	$SIG_ASY{$signal} ||= new Async::Interrupt
		1565	cb => sub { undef $SIG_EV{$signal} },
		1566	signal => $signal,
		1567	pipe => [$SIGPIPE_R->filenos],
		1568	pipe_autodrain => 0,
		1569	;
		1570
		1571	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1572	}
		1573	: sub {
		1574	my (undef, %arg) = @_;
		1575
		1576	# pure perl
		1577	my $signal = sig2name $arg{signal};
		1578	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1579
1057	$SIG{$signal} ||= sub {	1580	$SIG{$signal} ||= sub {
		1581	local $!;
		1582	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1583	undef $SIG_EV{$signal};
		1584	};
		1585
		1586	# can't do signal processing without introducing races in pure perl,
		1587	# so limit the signal latency.
		1588	_sig_add;
		1589
		1590	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1591	}
		1592	;
		1593
		1594	*AnyEvent::Base::signal::DESTROY = sub {
		1595	my ($signal, $cb) = @{$_[0]};
		1596
		1597	_sig_del;
		1598
		1599	delete $SIG_CB{$signal}{$cb};
		1600
		1601	$HAVE_ASYNC_INTERRUPT
		1602	? delete $SIG_ASY{$signal}
		1603	: # delete doesn't work with older perls - they then
		1604	# print weird messages, or just unconditionally exit
		1605	# instead of getting the default action.
		1606	undef $SIG{$signal}
		1607	unless keys %{ $SIG_CB{$signal} };
		1608	};
		1609
		1610	*_signal_exec = sub {
		1611	$HAVE_ASYNC_INTERRUPT
		1612	? $SIGPIPE_R->drain
		1613	: sysread $SIGPIPE_R, (my $dummy), 9;
		1614
		1615	while (%SIG_EV) {
		1616	for (keys %SIG_EV) {
		1617	delete $SIG_EV{$_};
1058	$_->() for values %{ $SIG_CB{$signal} || {} };	1618	$_->() for values %{ $SIG_CB{$_} || {} };
		1619	}
		1620	}
		1621	};
1059	};	1622	};
		1623	die if $@;
1060		1624
1061	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1625	&signal
1062	}
1063
1064	sub AnyEvent::Base::Signal::DESTROY {
1065	my ($signal, $cb) = @{$_[0]};
1066
1067	delete $SIG_CB{$signal}{$cb};
1068
1069	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1070	}	1626	}
1071		1627
1072	# default implementation for ->child	1628	# default implementation for ->child
1073		1629
1074	our %PID_CB;	1630	our %PID_CB;
1075	our $CHLD_W;	1631	our $CHLD_W;
1076	our $CHLD_DELAY_W;	1632	our $CHLD_DELAY_W;
1077	our $PID_IDLE;
1078	our $WNOHANG;	1633	our $WNOHANG;
1079		1634
1080	sub _child_wait {	1635	# used by many Impl's
1081	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1636	sub _emit_childstatus($$) {
		1637	my (undef, $rpid, $rstatus) = @_;
		1638
		1639	$_->($rpid, $rstatus)
1082	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1640	for values %{ $PID_CB{$rpid} || {} },
1083	(values %{ $PID_CB{0} || {} });	1641	values %{ $PID_CB{0} || {} };
1084	}
1085
1086	undef $PID_IDLE;
1087	}
1088
1089	sub _sigchld {
1090	# make sure we deliver these changes "synchronous" with the event loop.
1091	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1092	undef $CHLD_DELAY_W;
1093	&_child_wait;
1094	});
1095	}	1642	}
1096		1643
1097	sub child {	1644	sub child {
		1645	eval q{ # poor man's autoloading {}
		1646	*_sigchld = sub {
		1647	my $pid;
		1648
		1649	AnyEvent->_emit_childstatus ($pid, $?)
		1650	while ($pid = waitpid -1, $WNOHANG) > 0;
		1651	};
		1652
		1653	*child = sub {
1098	my (undef, %arg) = @_;	1654	my (undef, %arg) = @_;
1099		1655
1100	defined (my $pid = $arg{pid} + 0)	1656	defined (my $pid = $arg{pid} + 0)
1101	or Carp::croak "required option 'pid' is missing";	1657	or Carp::croak "required option 'pid' is missing";
1102		1658
1103	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1659	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1104		1660
1105	unless ($WNOHANG) {	1661	# WNOHANG is almost cetrainly 1 everywhere
		1662	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1663	? 1
1106	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1664	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1107	}
1108		1665
1109	unless ($CHLD_W) {	1666	unless ($CHLD_W) {
1110	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1667	$CHLD_W = AE::signal CHLD => \&_sigchld;
1111	# child could be a zombie already, so make at least one round	1668	# child could be a zombie already, so make at least one round
1112	&_sigchld;	1669	&_sigchld;
1113	}	1670	}
1114		1671
1115	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1672	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1116	}	1673	};
1117		1674
1118	sub AnyEvent::Base::Child::DESTROY {	1675	*AnyEvent::Base::child::DESTROY = sub {
1119	my ($pid, $cb) = @{$_[0]};	1676	my ($pid, $cb) = @{$_[0]};
1120		1677
1121	delete $PID_CB{$pid}{$cb};	1678	delete $PID_CB{$pid}{$cb};
1122	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1679	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1123		1680
1124	undef $CHLD_W unless keys %PID_CB;	1681	undef $CHLD_W unless keys %PID_CB;
		1682	};
		1683	};
		1684	die if $@;
		1685
		1686	&child
		1687	}
		1688
		1689	# idle emulation is done by simply using a timer, regardless
		1690	# of whether the process is idle or not, and not letting
		1691	# the callback use more than 50% of the time.
		1692	sub idle {
		1693	eval q{ # poor man's autoloading {}
		1694	*idle = sub {
		1695	my (undef, %arg) = @_;
		1696
		1697	my ($cb, $w, $rcb) = $arg{cb};
		1698
		1699	$rcb = sub {
		1700	if ($cb) {
		1701	$w = _time;
		1702	&$cb;
		1703	$w = _time - $w;
		1704
		1705	# never use more then 50% of the time for the idle watcher,
		1706	# within some limits
		1707	$w = 0.0001 if $w < 0.0001;
		1708	$w = 5 if $w > 5;
		1709
		1710	$w = AE::timer $w, 0, $rcb;
		1711	} else {
		1712	# clean up...
		1713	undef $w;
		1714	undef $rcb;
		1715	}
		1716	};
		1717
		1718	$w = AE::timer 0.05, 0, $rcb;
		1719
		1720	bless \\$cb, "AnyEvent::Base::idle"
		1721	};
		1722
		1723	*AnyEvent::Base::idle::DESTROY = sub {
		1724	undef $${$_[0]};
		1725	};
		1726	};
		1727	die if $@;
		1728
		1729	&idle
1125	}	1730	}
1126		1731
1127	package AnyEvent::CondVar;	1732	package AnyEvent::CondVar;
1128		1733
1129	our @ISA = AnyEvent::CondVar::Base::;	1734	our @ISA = AnyEvent::CondVar::Base::;
1130		1735
		1736	# only to be used for subclassing
		1737	sub new {
		1738	my $class = shift;
		1739	bless AnyEvent->condvar (@_), $class
		1740	}
		1741
1131	package AnyEvent::CondVar::Base;	1742	package AnyEvent::CondVar::Base;
1132		1743
1133	use overload	1744	#use overload
1134	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1745	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1135	fallback => 1;	1746	# fallback => 1;
		1747
		1748	# save 300+ kilobytes by dirtily hardcoding overloading
		1749	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1750	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1751	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1752	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1753
		1754	our $WAITING;
1136		1755
1137	sub _send {	1756	sub _send {
1138	# nop	1757	# nop
1139	}	1758	}
1140		1759
…		…
1153	sub ready {	1772	sub ready {
1154	$_[0]{_ae_sent}	1773	$_[0]{_ae_sent}
1155	}	1774	}
1156		1775
1157	sub _wait {	1776	sub _wait {
		1777	$WAITING
		1778	and !$_[0]{_ae_sent}
		1779	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1780
		1781	local $WAITING = 1;
1158	AnyEvent->one_event while !$_[0]{_ae_sent};	1782	AnyEvent->one_event while !$_[0]{_ae_sent};
1159	}	1783	}
1160		1784
1161	sub recv {	1785	sub recv {
1162	$_[0]->_wait;	1786	$_[0]->_wait;
…		…
1164	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1788	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1165	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1789	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1166	}	1790	}
1167		1791
1168	sub cb {	1792	sub cb {
1169	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1793	my $cv = shift;
		1794
		1795	@_
		1796	and $cv->{_ae_cb} = shift
		1797	and $cv->{_ae_sent}
		1798	and (delete $cv->{_ae_cb})->($cv);
		1799
1170	$_[0]{_ae_cb}	1800	$cv->{_ae_cb}
1171	}	1801	}
1172		1802
1173	sub begin {	1803	sub begin {
1174	++$_[0]{_ae_counter};	1804	++$_[0]{_ae_counter};
1175	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1805	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1203	so on.	1833	so on.
1204		1834
1205	=head1 ENVIRONMENT VARIABLES	1835	=head1 ENVIRONMENT VARIABLES
1206		1836
1207	The following environment variables are used by this module or its	1837	The following environment variables are used by this module or its
1208	submodules:	1838	submodules.
		1839
		1840	Note that AnyEvent will remove I<all> environment variables starting with
		1841	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1842	enabled.
1209		1843
1210	=over 4	1844	=over 4
1211		1845
1212	=item C<PERL_ANYEVENT_VERBOSE>	1846	=item C<PERL_ANYEVENT_VERBOSE>
1213		1847
…		…
1220	C<PERL_ANYEVENT_MODEL>.	1854	C<PERL_ANYEVENT_MODEL>.
1221		1855
1222	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1856	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1223	model it chooses.	1857	model it chooses.
1224		1858
		1859	When set to C<8> or higher, then AnyEvent will report extra information on
		1860	which optional modules it loads and how it implements certain features.
		1861
1225	=item C<PERL_ANYEVENT_STRICT>	1862	=item C<PERL_ANYEVENT_STRICT>
1226		1863
1227	AnyEvent does not do much argument checking by default, as thorough	1864	AnyEvent does not do much argument checking by default, as thorough
1228	argument checking is very costly. Setting this variable to a true value	1865	argument checking is very costly. Setting this variable to a true value
1229	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1866	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1230	check the arguments passed to most method calls. If it finds any problems	1867	check the arguments passed to most method calls. If it finds any problems,
1231	it will croak.	1868	it will croak.
1232		1869
1233	In other words, enables "strict" mode.	1870	In other words, enables "strict" mode.
1234		1871
1235	Unlike C<use strict>, it is definitely recommended ot keep it off in	1872	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1236	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1873	>>, it is definitely recommended to keep it off in production. Keeping
1237	developing programs can be very useful, however.	1874	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1875	can be very useful, however.
1238		1876
1239	=item C<PERL_ANYEVENT_MODEL>	1877	=item C<PERL_ANYEVENT_MODEL>
1240		1878
1241	This can be used to specify the event model to be used by AnyEvent, before	1879	This can be used to specify the event model to be used by AnyEvent, before
1242	auto detection and -probing kicks in. It must be a string consisting	1880	auto detection and -probing kicks in. It must be a string consisting
…		…
1263	used, and preference will be given to protocols mentioned earlier in the	1901	used, and preference will be given to protocols mentioned earlier in the
1264	list.	1902	list.
1265		1903
1266	This variable can effectively be used for denial-of-service attacks	1904	This variable can effectively be used for denial-of-service attacks
1267	against local programs (e.g. when setuid), although the impact is likely	1905	against local programs (e.g. when setuid), although the impact is likely
1268	small, as the program has to handle connection errors already-	1906	small, as the program has to handle conenction and other failures anyways.
1269		1907
1270	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,	1908	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1271	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>	1909	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1272	- only support IPv4, never try to resolve or contact IPv6	1910	- only support IPv4, never try to resolve or contact IPv6
1273	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or	1911	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
…		…
1285		1923
1286	=item C<PERL_ANYEVENT_MAX_FORKS>	1924	=item C<PERL_ANYEVENT_MAX_FORKS>
1287		1925
1288	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1926	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1289	will create in parallel.	1927	will create in parallel.
		1928
		1929	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1930
		1931	The default value for the C<max_outstanding> parameter for the default DNS
		1932	resolver - this is the maximum number of parallel DNS requests that are
		1933	sent to the DNS server.
		1934
		1935	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1936
		1937	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1938	configuration) in the default resolver. When set to the empty string, no
		1939	default config will be used.
		1940
		1941	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1942
		1943	When neither C<ca_file> nor C<ca_path> was specified during
		1944	L<AnyEvent::TLS> context creation, and either of these environment
		1945	variables exist, they will be used to specify CA certificate locations
		1946	instead of a system-dependent default.
		1947
		1948	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1949
		1950	When these are set to C<1>, then the respective modules are not
		1951	loaded. Mostly good for testing AnyEvent itself.
1290		1952
1291	=back	1953	=back
1292		1954
1293	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1955	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1294		1956
…		…
1352	warn "read: $input\n"; # output what has been read	2014	warn "read: $input\n"; # output what has been read
1353	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2015	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1354	},	2016	},
1355	);	2017	);
1356		2018
1357	my $time_watcher; # can only be used once
1358
1359	sub new_timer {
1360	$timer = AnyEvent->timer (after => 1, cb => sub {	2019	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1361	warn "timeout\n"; # print 'timeout' about every second	2020	warn "timeout\n"; # print 'timeout' at most every second
1362	&new_timer; # and restart the time
1363	});	2021	});
1364	}
1365
1366	new_timer; # create first timer
1367		2022
1368	$cv->recv; # wait until user enters /^q/i	2023	$cv->recv; # wait until user enters /^q/i
1369		2024
1370	=head1 REAL-WORLD EXAMPLE	2025	=head1 REAL-WORLD EXAMPLE
1371		2026
…		…
1444		2099
1445	The actual code goes further and collects all errors (C<die>s, exceptions)	2100	The actual code goes further and collects all errors (C<die>s, exceptions)
1446	that occurred during request processing. The C<result> method detects	2101	that occurred during request processing. The C<result> method detects
1447	whether an exception as thrown (it is stored inside the $txn object)	2102	whether an exception as thrown (it is stored inside the $txn object)
1448	and just throws the exception, which means connection errors and other	2103	and just throws the exception, which means connection errors and other
1449	problems get reported tot he code that tries to use the result, not in a	2104	problems get reported to the code that tries to use the result, not in a
1450	random callback.	2105	random callback.
1451		2106
1452	All of this enables the following usage styles:	2107	All of this enables the following usage styles:
1453		2108
1454	1. Blocking:	2109	1. Blocking:
…		…
1502	through AnyEvent. The benchmark creates a lot of timers (with a zero	2157	through AnyEvent. The benchmark creates a lot of timers (with a zero
1503	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2158	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1504	which it is), lets them fire exactly once and destroys them again.	2159	which it is), lets them fire exactly once and destroys them again.
1505		2160
1506	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2161	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1507	distribution.	2162	distribution. It uses the L<AE> interface, which makes a real difference
		2163	for the EV and Perl backends only.
1508		2164
1509	=head3 Explanation of the columns	2165	=head3 Explanation of the columns
1510		2166
1511	I<watcher> is the number of event watchers created/destroyed. Since	2167	I<watcher> is the number of event watchers created/destroyed. Since
1512	different event models feature vastly different performances, each event	2168	different event models feature vastly different performances, each event
…		…
1533	watcher.	2189	watcher.
1534		2190
1535	=head3 Results	2191	=head3 Results
1536		2192
1537	name watchers bytes create invoke destroy comment	2193	name watchers bytes create invoke destroy comment
1538	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2194	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1539	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2195	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1540	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2196	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1541	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2197	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1542	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2198	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1543	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2199	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2200	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2201	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1544	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2202	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1545	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2203	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1546	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2204	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1547	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2205	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1548		2206
1549	=head3 Discussion	2207	=head3 Discussion
1550		2208
1551	The benchmark does I<not> measure scalability of the event loop very	2209	The benchmark does I<not> measure scalability of the event loop very
1552	well. For example, a select-based event loop (such as the pure perl one)	2210	well. For example, a select-based event loop (such as the pure perl one)
…		…
1564	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2222	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1565	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2223	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1566	cycles with POE.	2224	cycles with POE.
1567		2225
1568	C<EV> is the sole leader regarding speed and memory use, which are both	2226	C<EV> is the sole leader regarding speed and memory use, which are both
1569	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2227	maximal/minimal, respectively. When using the L<AE> API there is zero
		2228	overhead (when going through the AnyEvent API create is about 5-6 times
		2229	slower, with other times being equal, so still uses far less memory than
1570	far less memory than any other event loop and is still faster than Event	2230	any other event loop and is still faster than Event natively).
1571	natively.
1572		2231
1573	The pure perl implementation is hit in a few sweet spots (both the	2232	The pure perl implementation is hit in a few sweet spots (both the
1574	constant timeout and the use of a single fd hit optimisations in the perl	2233	constant timeout and the use of a single fd hit optimisations in the perl
1575	interpreter and the backend itself). Nevertheless this shows that it	2234	interpreter and the backend itself). Nevertheless this shows that it
1576	adds very little overhead in itself. Like any select-based backend its	2235	adds very little overhead in itself. Like any select-based backend its
1577	performance becomes really bad with lots of file descriptors (and few of	2236	performance becomes really bad with lots of file descriptors (and few of
1578	them active), of course, but this was not subject of this benchmark.	2237	them active), of course, but this was not subject of this benchmark.
1579		2238
1580	The C<Event> module has a relatively high setup and callback invocation	2239	The C<Event> module has a relatively high setup and callback invocation
1581	cost, but overall scores in on the third place.	2240	cost, but overall scores in on the third place.
		2241
		2242	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2243	when using its pure perl backend.
1582		2244
1583	C<Glib>'s memory usage is quite a bit higher, but it features a	2245	C<Glib>'s memory usage is quite a bit higher, but it features a
1584	faster callback invocation and overall ends up in the same class as	2246	faster callback invocation and overall ends up in the same class as
1585	C<Event>. However, Glib scales extremely badly, doubling the number of	2247	C<Event>. However, Glib scales extremely badly, doubling the number of
1586	watchers increases the processing time by more than a factor of four,	2248	watchers increases the processing time by more than a factor of four,
…		…
1647	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2309	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1648	(1%) are active. This mirrors the activity of large servers with many	2310	(1%) are active. This mirrors the activity of large servers with many
1649	connections, most of which are idle at any one point in time.	2311	connections, most of which are idle at any one point in time.
1650		2312
1651	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2313	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1652	distribution.	2314	distribution. It uses the L<AE> interface, which makes a real difference
		2315	for the EV and Perl backends only.
1653		2316
1654	=head3 Explanation of the columns	2317	=head3 Explanation of the columns
1655		2318
1656	I<sockets> is the number of sockets, and twice the number of "servers" (as	2319	I<sockets> is the number of sockets, and twice the number of "servers" (as
1657	each server has a read and write socket end).	2320	each server has a read and write socket end).
…		…
1664	it to another server. This includes deleting the old timeout and creating	2327	it to another server. This includes deleting the old timeout and creating
1665	a new one that moves the timeout into the future.	2328	a new one that moves the timeout into the future.
1666		2329
1667	=head3 Results	2330	=head3 Results
1668		2331
1669	name sockets create request	2332	name sockets create request
1670	EV 20000 69.01 11.16	2333	EV 20000 62.66 7.99
1671	Perl 20000 73.32 35.87	2334	Perl 20000 68.32 32.64
1672	Event 20000 212.62 257.32	2335	IOAsync 20000 174.06 101.15 epoll
1673	Glib 20000 651.16 1896.30	2336	IOAsync 20000 174.67 610.84 poll
		2337	Event 20000 202.69 242.91
		2338	Glib 20000 557.01 1689.52
1674	POE 20000 349.67 12317.24 uses POE::Loop::Event	2339	POE 20000 341.54 12086.32 uses POE::Loop::Event
1675		2340
1676	=head3 Discussion	2341	=head3 Discussion
1677		2342
1678	This benchmark I<does> measure scalability and overall performance of the	2343	This benchmark I<does> measure scalability and overall performance of the
1679	particular event loop.	2344	particular event loop.
…		…
1681	EV is again fastest. Since it is using epoll on my system, the setup time	2346	EV is again fastest. Since it is using epoll on my system, the setup time
1682	is relatively high, though.	2347	is relatively high, though.
1683		2348
1684	Perl surprisingly comes second. It is much faster than the C-based event	2349	Perl surprisingly comes second. It is much faster than the C-based event
1685	loops Event and Glib.	2350	loops Event and Glib.
		2351
		2352	IO::Async performs very well when using its epoll backend, and still quite
		2353	good compared to Glib when using its pure perl backend.
1686		2354
1687	Event suffers from high setup time as well (look at its code and you will	2355	Event suffers from high setup time as well (look at its code and you will
1688	understand why). Callback invocation also has a high overhead compared to	2356	understand why). Callback invocation also has a high overhead compared to
1689	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2357	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1690	uses select or poll in basically all documented configurations.	2358	uses select or poll in basically all documented configurations.
…		…
1753	=item * C-based event loops perform very well with small number of	2421	=item * C-based event loops perform very well with small number of
1754	watchers, as the management overhead dominates.	2422	watchers, as the management overhead dominates.
1755		2423
1756	=back	2424	=back
1757		2425
		2426	=head2 THE IO::Lambda BENCHMARK
		2427
		2428	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2429	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2430	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2431	shouldn't come as a surprise to anybody). As such, the benchmark is
		2432	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2433	very optimal. But how would AnyEvent compare when used without the extra
		2434	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2435
		2436	The benchmark itself creates an echo-server, and then, for 500 times,
		2437	connects to the echo server, sends a line, waits for the reply, and then
		2438	creates the next connection. This is a rather bad benchmark, as it doesn't
		2439	test the efficiency of the framework or much non-blocking I/O, but it is a
		2440	benchmark nevertheless.
		2441
		2442	name runtime
		2443	Lambda/select 0.330 sec
		2444	+ optimized 0.122 sec
		2445	Lambda/AnyEvent 0.327 sec
		2446	+ optimized 0.138 sec
		2447	Raw sockets/select 0.077 sec
		2448	POE/select, components 0.662 sec
		2449	POE/select, raw sockets 0.226 sec
		2450	POE/select, optimized 0.404 sec
		2451
		2452	AnyEvent/select/nb 0.085 sec
		2453	AnyEvent/EV/nb 0.068 sec
		2454	+state machine 0.134 sec
		2455
		2456	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2457	benchmarks actually make blocking connects and use 100% blocking I/O,
		2458	defeating the purpose of an event-based solution. All of the newly
		2459	written AnyEvent benchmarks use 100% non-blocking connects (using
		2460	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2461	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2462	generally require a lot more bookkeeping and event handling than blocking
		2463	connects (which involve a single syscall only).
		2464
		2465	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2466	offers similar expressive power as POE and IO::Lambda, using conventional
		2467	Perl syntax. This means that both the echo server and the client are 100%
		2468	non-blocking, further placing it at a disadvantage.
		2469
		2470	As you can see, the AnyEvent + EV combination even beats the
		2471	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2472	backend easily beats IO::Lambda and POE.
		2473
		2474	And even the 100% non-blocking version written using the high-level (and
		2475	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2476	higher level ("unoptimised") abstractions by a large margin, even though
		2477	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2478
		2479	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2480	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2481	part of the IO::Lambda distribution and were used without any changes.
		2482
		2483
		2484	=head1 SIGNALS
		2485
		2486	AnyEvent currently installs handlers for these signals:
		2487
		2488	=over 4
		2489
		2490	=item SIGCHLD
		2491
		2492	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2493	emulation for event loops that do not support them natively. Also, some
		2494	event loops install a similar handler.
		2495
		2496	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2497	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2498
		2499	=item SIGPIPE
		2500
		2501	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2502	when AnyEvent gets loaded.
		2503
		2504	The rationale for this is that AnyEvent users usually do not really depend
		2505	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2506	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2507	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2508	some random socket.
		2509
		2510	The rationale for installing a no-op handler as opposed to ignoring it is
		2511	that this way, the handler will be restored to defaults on exec.
		2512
		2513	Feel free to install your own handler, or reset it to defaults.
		2514
		2515	=back
		2516
		2517	=cut
		2518
		2519	undef $SIG{CHLD}
		2520	if $SIG{CHLD} eq 'IGNORE';
		2521
		2522	$SIG{PIPE} = sub { }
		2523	unless defined $SIG{PIPE};
		2524
		2525	=head1 RECOMMENDED/OPTIONAL MODULES
		2526
		2527	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2528	its built-in modules) are required to use it.
		2529
		2530	That does not mean that AnyEvent won't take advantage of some additional
		2531	modules if they are installed.
		2532
		2533	This section explains which additional modules will be used, and how they
		2534	affect AnyEvent's operation.
		2535
		2536	=over 4
		2537
		2538	=item L<Async::Interrupt>
		2539
		2540	This slightly arcane module is used to implement fast signal handling: To
		2541	my knowledge, there is no way to do completely race-free and quick
		2542	signal handling in pure perl. To ensure that signals still get
		2543	delivered, AnyEvent will start an interval timer to wake up perl (and
		2544	catch the signals) with some delay (default is 10 seconds, look for
		2545	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2546
		2547	If this module is available, then it will be used to implement signal
		2548	catching, which means that signals will not be delayed, and the event loop
		2549	will not be interrupted regularly, which is more efficient (and good for
		2550	battery life on laptops).
		2551
		2552	This affects not just the pure-perl event loop, but also other event loops
		2553	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2554
		2555	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2556	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2557	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2558	does nothing for those backends.
		2559
		2560	=item L<EV>
		2561
		2562	This module isn't really "optional", as it is simply one of the backend
		2563	event loops that AnyEvent can use. However, it is simply the best event
		2564	loop available in terms of features, speed and stability: It supports
		2565	the AnyEvent API optimally, implements all the watcher types in XS, does
		2566	automatic timer adjustments even when no monotonic clock is available,
		2567	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2568	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2569	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2570
		2571	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2572	then this module will do nothing for you.
		2573
		2574	=item L<Guard>
		2575
		2576	The guard module, when used, will be used to implement
		2577	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2578	lot less memory), but otherwise doesn't affect guard operation much. It is
		2579	purely used for performance.
		2580
		2581	=item L<JSON> and L<JSON::XS>
		2582
		2583	One of these modules is required when you want to read or write JSON data
		2584	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2585	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2586
		2587	=item L<Net::SSLeay>
		2588
		2589	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2590	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2591	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2592
		2593	=item L<Time::HiRes>
		2594
		2595	This module is part of perl since release 5.008. It will be used when the
		2596	chosen event library does not come with a timing source of its own. The
		2597	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2598	try to use a monotonic clock for timing stability.
		2599
		2600	=back
		2601
1758		2602
1759	=head1 FORK	2603	=head1 FORK
1760		2604
1761	Most event libraries are not fork-safe. The ones who are usually are	2605	Most event libraries are not fork-safe. The ones who are usually are
1762	because they rely on inefficient but fork-safe C<select> or C<poll>	2606	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1763	calls. Only L<EV> is fully fork-aware.	2607	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2608	are usually badly thought-out hacks that are incompatible with fork in
		2609	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2610	continue event-processing in both parent and child (or both, if you know
		2611	what you are doing).
		2612
		2613	This means that, in general, you cannot fork and do event processing in
		2614	the child if the event library was initialised before the fork (which
		2615	usually happens when the first AnyEvent watcher is created, or the library
		2616	is loaded).
1764		2617
1765	If you have to fork, you must either do so I<before> creating your first	2618	If you have to fork, you must either do so I<before> creating your first
1766	watcher OR you must not use AnyEvent at all in the child.	2619	watcher OR you must not use AnyEvent at all in the child OR you must do
		2620	something completely out of the scope of AnyEvent.
		2621
		2622	The problem of doing event processing in the parent I<and> the child
		2623	is much more complicated: even for backends that I<are> fork-aware or
		2624	fork-safe, their behaviour is not usually what you want: fork clones all
		2625	watchers, that means all timers, I/O watchers etc. are active in both
		2626	parent and child, which is almost never what you want. USing C<exec>
		2627	to start worker children from some kind of manage rprocess is usually
		2628	preferred, because it is much easier and cleaner, at the expense of having
		2629	to have another binary.
1767		2630
1768		2631
1769	=head1 SECURITY CONSIDERATIONS	2632	=head1 SECURITY CONSIDERATIONS
1770		2633
1771	AnyEvent can be forced to load any event model via	2634	AnyEvent can be forced to load any event model via
…		…
1783	use AnyEvent;	2646	use AnyEvent;
1784		2647
1785	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2648	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1786	be used to probe what backend is used and gain other information (which is	2649	be used to probe what backend is used and gain other information (which is
1787	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2650	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1788	$ENV{PERL_ANYEGENT_STRICT}.	2651	$ENV{PERL_ANYEVENT_STRICT}.
		2652
		2653	Note that AnyEvent will remove I<all> environment variables starting with
		2654	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2655	enabled.
1789		2656
1790		2657
1791	=head1 BUGS	2658	=head1 BUGS
1792		2659
1793	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2660	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1794	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2661	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1795	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2662	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1796	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2663	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1797	pronounced).	2664	pronounced).
1798		2665
1799		2666
1800	=head1 SEE ALSO	2667	=head1 SEE ALSO
		2668
		2669	Tutorial/Introduction: L<AnyEvent::Intro>.
		2670
		2671	FAQ: L<AnyEvent::FAQ>.
1801		2672
1802	Utility functions: L<AnyEvent::Util>.	2673	Utility functions: L<AnyEvent::Util>.
1803		2674
1804	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2675	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1805	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2676	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1806		2677
1807	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2678	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1808	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2679	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1809	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2680	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1810	L<AnyEvent::Impl::POE>.	2681	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1811		2682
1812	Non-blocking file handles, sockets, TCP clients and	2683	Non-blocking file handles, sockets, TCP clients and
1813	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2684	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1814		2685
1815	Asynchronous DNS: L<AnyEvent::DNS>.	2686	Asynchronous DNS: L<AnyEvent::DNS>.
1816		2687
1817	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2688	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1818		2689
1819	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2690	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2691	L<AnyEvent::HTTP>.
1820		2692
1821		2693
1822	=head1 AUTHOR	2694	=head1 AUTHOR
1823		2695
1824	Marc Lehmann <schmorp@schmorp.de>	2696	Marc Lehmann <schmorp@schmorp.de>

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