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Revision 1.331 by root, Tue Aug 31 01:00:48 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
11	# file descriptor readable	15	# file handle or descriptor readable
12	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
13		17
14	# one-shot or repeating timers	18	# one-shot or repeating timers
15	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
16	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
17		21
18	print AnyEvent->now; # prints current event loop time	22	print AnyEvent->now; # prints current event loop time
19	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
20		24
21	# POSIX signal	25	# POSIX signal
…		…
39	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
40		44
41	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
42	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
43	L<AnyEvent::Intro> manpage.	47	L<AnyEvent::Intro> manpage.
		48
		49	=head1 SUPPORT
		50
		51	There is a mailinglist for discussing all things AnyEvent, and an IRC
		52	channel, too.
		53
		54	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		55	Repository>, at L<http://anyevent.schmorp.de>, for more info.
44		56
45	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	57	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
46		58
47	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	59	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
48	nowadays. So what is different about AnyEvent?	60	nowadays. So what is different about AnyEvent?
…		…
64	module users into the same thing by forcing them to use the same event	76	module users into the same thing by forcing them to use the same event
65	model you use.	77	model you use.
66		78
67	For modules like POE or IO::Async (which is a total misnomer as it is	79	For modules like POE or IO::Async (which is a total misnomer as it is
68	actually doing all I/O I<synchronously>...), using them in your module is	80	actually doing all I/O I<synchronously>...), using them in your module is
69	like joining a cult: After you joined, you are dependent on them and you	81	like joining a cult: After you join, you are dependent on them and you
70	cannot use anything else, as they are simply incompatible to everything	82	cannot use anything else, as they are simply incompatible to everything
71	that isn't them. What's worse, all the potential users of your	83	that isn't them. What's worse, all the potential users of your
72	module are I<also> forced to use the same event loop you use.	84	module are I<also> forced to use the same event loop you use.
73		85
74	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	86	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
75	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	87	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
76	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	88	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
77	your module uses one of those, every user of your module has to use it,	89	your module uses one of those, every user of your module has to use it,
78	too. But if your module uses AnyEvent, it works transparently with all	90	too. But if your module uses AnyEvent, it works transparently with all
79	event models it supports (including stuff like IO::Async, as long as those	91	event models it supports (including stuff like IO::Async, as long as those
80	use one of the supported event loops. It is trivial to add new event loops	92	use one of the supported event loops. It is easy to add new event loops
81	to AnyEvent, too, so it is future-proof).	93	to AnyEvent, too, so it is future-proof).
82		94
83	In addition to being free of having to use I<the one and only true event	95	In addition to being free of having to use I<the one and only true event
84	model>, AnyEvent also is free of bloat and policy: with POE or similar	96	model>, AnyEvent also is free of bloat and policy: with POE or similar
85	modules, you get an enormous amount of code and strict rules you have to	97	modules, you get an enormous amount of code and strict rules you have to
86	follow. AnyEvent, on the other hand, is lean and up to the point, by only	98	follow. AnyEvent, on the other hand, is lean and to the point, by only
87	offering the functionality that is necessary, in as thin as a wrapper as	99	offering the functionality that is necessary, in as thin as a wrapper as
88	technically possible.	100	technically possible.
89		101
90	Of course, AnyEvent comes with a big (and fully optional!) toolbox	102	Of course, AnyEvent comes with a big (and fully optional!) toolbox
91	of useful functionality, such as an asynchronous DNS resolver, 100%	103	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
97	useful) and you want to force your users to use the one and only event	109	useful) and you want to force your users to use the one and only event
98	model, you should I<not> use this module.	110	model, you should I<not> use this module.
99		111
100	=head1 DESCRIPTION	112	=head1 DESCRIPTION
101		113
102	L<AnyEvent> provides an identical interface to multiple event loops. This	114	L<AnyEvent> provides a uniform interface to various event loops. This
103	allows module authors to utilise an event loop without forcing module	115	allows module authors to use event loop functionality without forcing
104	users to use the same event loop (as only a single event loop can coexist	116	module users to use a specific event loop implementation (since more
105	peacefully at any one time).	117	than one event loop cannot coexist peacefully).
106		118
107	The interface itself is vaguely similar, but not identical to the L<Event>	119	The interface itself is vaguely similar, but not identical to the L<Event>
108	module.	120	module.
109		121
110	During the first call of any watcher-creation method, the module tries	122	During the first call of any watcher-creation method, the module tries
111	to detect the currently loaded event loop by probing whether one of the	123	to detect the currently loaded event loop by probing whether one of the
112	following modules is already loaded: L<EV>,	124	following modules is already loaded: L<EV>, L<AnyEvent::Impl::Perl>,
113	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	125	L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
114	L<POE>. The first one found is used. If none are found, the module tries	126	found is used. If none are detected, the module tries to load the first
115	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	127	four modules in the order given; but note that if L<EV> is not
116	adaptor should always succeed) in the order given. The first one that can	128	available, the pure-perl L<AnyEvent::Impl::Perl> should always work, so
117	be successfully loaded will be used. If, after this, still none could be	129	the other two are not normally tried.
118	found, AnyEvent will fall back to a pure-perl event loop, which is not
119	very efficient, but should work everywhere.
120		130
121	Because AnyEvent first checks for modules that are already loaded, loading	131	Because AnyEvent first checks for modules that are already loaded, loading
122	an event model explicitly before first using AnyEvent will likely make	132	an event model explicitly before first using AnyEvent will likely make
123	that model the default. For example:	133	that model the default. For example:
124		134
…		…
126	use AnyEvent;	136	use AnyEvent;
127		137
128	# .. AnyEvent will likely default to Tk	138	# .. AnyEvent will likely default to Tk
129		139
130	The I<likely> means that, if any module loads another event model and	140	The I<likely> means that, if any module loads another event model and
131	starts using it, all bets are off. Maybe you should tell their authors to	141	starts using it, all bets are off - this case should be very rare though,
132	use AnyEvent so their modules work together with others seamlessly...	142	as very few modules hardcode event loops without announcing this very
		143	loudly.
133		144
134	The pure-perl implementation of AnyEvent is called	145	The pure-perl implementation of AnyEvent is called
135	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	146	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
136	explicitly and enjoy the high availability of that event loop :)	147	explicitly and enjoy the high availability of that event loop :)
137		148
…		…
146	callback when the event occurs (of course, only when the event model	157	callback when the event occurs (of course, only when the event model
147	is in control).	158	is in control).
148		159
149	Note that B<callbacks must not permanently change global variables>	160	Note that B<callbacks must not permanently change global variables>
150	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<	161	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
151	callbacks must not C<die> >>. The former is good programming practise in	162	callbacks must not C<die> >>. The former is good programming practice in
152	Perl and the latter stems from the fact that exception handling differs	163	Perl and the latter stems from the fact that exception handling differs
153	widely between event loops.	164	widely between event loops.
154		165
155	To disable the watcher you have to destroy it (e.g. by setting the	166	To disable a watcher you have to destroy it (e.g. by setting the
156	variable you store it in to C<undef> or otherwise deleting all references	167	variable you store it in to C<undef> or otherwise deleting all references
157	to it).	168	to it).
158		169
159	All watchers are created by calling a method on the C<AnyEvent> class.	170	All watchers are created by calling a method on the C<AnyEvent> class.
160		171
161	Many watchers either are used with "recursion" (repeating timers for	172	Many watchers either are used with "recursion" (repeating timers for
162	example), or need to refer to their watcher object in other ways.	173	example), or need to refer to their watcher object in other ways.
163		174
164	An any way to achieve that is this pattern:	175	One way to achieve that is this pattern:
165		176
166	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	177	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
167	# you can use $w here, for example to undef it	178	# you can use $w here, for example to undef it
168	undef $w;	179	undef $w;
169	});	180	});
…		…
172	my variables are only visible after the statement in which they are	183	my variables are only visible after the statement in which they are
173	declared.	184	declared.
174		185
175	=head2 I/O WATCHERS	186	=head2 I/O WATCHERS
176		187
		188	$w = AnyEvent->io (
		189	fh => <filehandle_or_fileno>,
		190	poll => <"r" or "w">,
		191	cb => <callback>,
		192	);
		193
177	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	194	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
178	with the following mandatory key-value pairs as arguments:	195	with the following mandatory key-value pairs as arguments:
179		196
180	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch	197	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
181	for events (AnyEvent might or might not keep a reference to this file	198	for events (AnyEvent might or might not keep a reference to this file
182	handle). Note that only file handles pointing to things for which	199	handle). Note that only file handles pointing to things for which
183	non-blocking operation makes sense are allowed. This includes sockets,	200	non-blocking operation makes sense are allowed. This includes sockets,
184	most character devices, pipes, fifos and so on, but not for example files	201	most character devices, pipes, fifos and so on, but not for example files
185	or block devices.	202	or block devices.
…		…
195		212
196	The I/O watcher might use the underlying file descriptor or a copy of it.	213	The I/O watcher might use the underlying file descriptor or a copy of it.
197	You must not close a file handle as long as any watcher is active on the	214	You must not close a file handle as long as any watcher is active on the
198	underlying file descriptor.	215	underlying file descriptor.
199		216
200	Some event loops issue spurious readyness notifications, so you should	217	Some event loops issue spurious readiness notifications, so you should
201	always use non-blocking calls when reading/writing from/to your file	218	always use non-blocking calls when reading/writing from/to your file
202	handles.	219	handles.
203		220
204	Example: wait for readability of STDIN, then read a line and disable the	221	Example: wait for readability of STDIN, then read a line and disable the
205	watcher.	222	watcher.
…		…
210	undef $w;	227	undef $w;
211	});	228	});
212		229
213	=head2 TIME WATCHERS	230	=head2 TIME WATCHERS
214		231
		232	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		233
		234	$w = AnyEvent->timer (
		235	after => <fractional_seconds>,
		236	interval => <fractional_seconds>,
		237	cb => <callback>,
		238	);
		239
215	You can create a time watcher by calling the C<< AnyEvent->timer >>	240	You can create a time watcher by calling the C<< AnyEvent->timer >>
216	method with the following mandatory arguments:	241	method with the following mandatory arguments:
217		242
218	C<after> specifies after how many seconds (fractional values are	243	C<after> specifies after how many seconds (fractional values are
219	supported) the callback should be invoked. C<cb> is the callback to invoke	244	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
221		246
222	Although the callback might get passed parameters, their value and	247	Although the callback might get passed parameters, their value and
223	presence is undefined and you cannot rely on them. Portable AnyEvent	248	presence is undefined and you cannot rely on them. Portable AnyEvent
224	callbacks cannot use arguments passed to time watcher callbacks.	249	callbacks cannot use arguments passed to time watcher callbacks.
225		250
226	The callback will normally be invoked once only. If you specify another	251	The callback will normally be invoked only once. If you specify another
227	parameter, C<interval>, as a strictly positive number (> 0), then the	252	parameter, C<interval>, as a strictly positive number (> 0), then the
228	callback will be invoked regularly at that interval (in fractional	253	callback will be invoked regularly at that interval (in fractional
229	seconds) after the first invocation. If C<interval> is specified with a	254	seconds) after the first invocation. If C<interval> is specified with a
230	false value, then it is treated as if it were missing.	255	false value, then it is treated as if it were not specified at all.
231		256
232	The callback will be rescheduled before invoking the callback, but no	257	The callback will be rescheduled before invoking the callback, but no
233	attempt is done to avoid timer drift in most backends, so the interval is	258	attempt is made to avoid timer drift in most backends, so the interval is
234	only approximate.	259	only approximate.
235		260
236	Example: fire an event after 7.7 seconds.	261	Example: fire an event after 7.7 seconds.
237		262
238	my $w = AnyEvent->timer (after => 7.7, cb => sub {	263	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
256		281
257	While most event loops expect timers to specified in a relative way, they	282	While most event loops expect timers to specified in a relative way, they
258	use absolute time internally. This makes a difference when your clock	283	use absolute time internally. This makes a difference when your clock
259	"jumps", for example, when ntp decides to set your clock backwards from	284	"jumps", for example, when ntp decides to set your clock backwards from
260	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to	285	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
261	fire "after" a second might actually take six years to finally fire.	286	fire "after a second" might actually take six years to finally fire.
262		287
263	AnyEvent cannot compensate for this. The only event loop that is conscious	288	AnyEvent cannot compensate for this. The only event loop that is conscious
264	about these issues is L<EV>, which offers both relative (ev_timer, based	289	of these issues is L<EV>, which offers both relative (ev_timer, based
265	on true relative time) and absolute (ev_periodic, based on wallclock time)	290	on true relative time) and absolute (ev_periodic, based on wallclock time)
266	timers.	291	timers.
267		292
268	AnyEvent always prefers relative timers, if available, matching the	293	AnyEvent always prefers relative timers, if available, matching the
269	AnyEvent API.	294	AnyEvent API.
…		…
291	I<In almost all cases (in all cases if you don't care), this is the	316	I<In almost all cases (in all cases if you don't care), this is the
292	function to call when you want to know the current time.>	317	function to call when you want to know the current time.>
293		318
294	This function is also often faster then C<< AnyEvent->time >>, and	319	This function is also often faster then C<< AnyEvent->time >>, and
295	thus the preferred method if you want some timestamp (for example,	320	thus the preferred method if you want some timestamp (for example,
296	L<AnyEvent::Handle> uses this to update it's activity timeouts).	321	L<AnyEvent::Handle> uses this to update its activity timeouts).
297		322
298	The rest of this section is only of relevance if you try to be very exact	323	The rest of this section is only of relevance if you try to be very exact
299	with your timing, you can skip it without bad conscience.	324	with your timing; you can skip it without a bad conscience.
300		325
301	For a practical example of when these times differ, consider L<Event::Lib>	326	For a practical example of when these times differ, consider L<Event::Lib>
302	and L<EV> and the following set-up:	327	and L<EV> and the following set-up:
303		328
304	The event loop is running and has just invoked one of your callback at	329	The event loop is running and has just invoked one of your callbacks at
305	time=500 (assume no other callbacks delay processing). In your callback,	330	time=500 (assume no other callbacks delay processing). In your callback,
306	you wait a second by executing C<sleep 1> (blocking the process for a	331	you wait a second by executing C<sleep 1> (blocking the process for a
307	second) and then (at time=501) you create a relative timer that fires	332	second) and then (at time=501) you create a relative timer that fires
308	after three seconds.	333	after three seconds.
309		334
…		…
340	might affect timers and time-outs.	365	might affect timers and time-outs.
341		366
342	When this is the case, you can call this method, which will update the	367	When this is the case, you can call this method, which will update the
343	event loop's idea of "current time".	368	event loop's idea of "current time".
344		369
		370	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		371	when mod_perl executes the script, then the event loop will have the wrong
		372	idea about the "current time" (being potentially far in the past, when the
		373	script ran the last time). In that case you should arrange a call to C<<
		374	AnyEvent->now_update >> each time the web server process wakes up again
		375	(e.g. at the start of your script, or in a handler).
		376
345	Note that updating the time I<might> cause some events to be handled.	377	Note that updating the time I<might> cause some events to be handled.
346		378
347	=back	379	=back
348		380
349	=head2 SIGNAL WATCHERS	381	=head2 SIGNAL WATCHERS
		382
		383	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
350		384
351	You can watch for signals using a signal watcher, C<signal> is the signal	385	You can watch for signals using a signal watcher, C<signal> is the signal
352	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl	386	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
353	callback to be invoked whenever a signal occurs.	387	callback to be invoked whenever a signal occurs.
354		388
…		…
360	invocation, and callback invocation will be synchronous. Synchronous means	394	invocation, and callback invocation will be synchronous. Synchronous means
361	that it might take a while until the signal gets handled by the process,	395	that it might take a while until the signal gets handled by the process,
362	but it is guaranteed not to interrupt any other callbacks.	396	but it is guaranteed not to interrupt any other callbacks.
363		397
364	The main advantage of using these watchers is that you can share a signal	398	The main advantage of using these watchers is that you can share a signal
365	between multiple watchers.	399	between multiple watchers, and AnyEvent will ensure that signals will not
		400	interrupt your program at bad times.
366		401
367	This watcher might use C<%SIG>, so programs overwriting those signals	402	This watcher might use C<%SIG> (depending on the event loop used),
368	directly will likely not work correctly.	403	so programs overwriting those signals directly will likely not work
		404	correctly.
369		405
370	Example: exit on SIGINT	406	Example: exit on SIGINT
371		407
372	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	408	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
373		409
		410	=head3 Restart Behaviour
		411
		412	While restart behaviour is up to the event loop implementation, most will
		413	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		414	pure perl implementation).
		415
		416	=head3 Safe/Unsafe Signals
		417
		418	Perl signals can be either "safe" (synchronous to opcode handling) or
		419	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		420	latter might corrupt your memory.
		421
		422	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		423	i.e. they will not interrupt your running perl program but will only be
		424	called as part of the normal event handling (just like timer, I/O etc.
		425	callbacks, too).
		426
		427	=head3 Signal Races, Delays and Workarounds
		428
		429	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		430	callbacks to signals in a generic way, which is a pity, as you cannot
		431	do race-free signal handling in perl, requiring C libraries for
		432	this. AnyEvent will try to do its best, which means in some cases,
		433	signals will be delayed. The maximum time a signal might be delayed is
		434	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		435	variable can be changed only before the first signal watcher is created,
		436	and should be left alone otherwise. This variable determines how often
		437	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		438	will cause fewer spurious wake-ups, which is better for power and CPU
		439	saving.
		440
		441	All these problems can be avoided by installing the optional
		442	L<Async::Interrupt> module, which works with most event loops. It will not
		443	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		444	(and not with L<POE> currently, as POE does its own workaround with
		445	one-second latency). For those, you just have to suffer the delays.
		446
374	=head2 CHILD PROCESS WATCHERS	447	=head2 CHILD PROCESS WATCHERS
375		448
		449	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		450
376	You can also watch on a child process exit and catch its exit status.	451	You can also watch for a child process exit and catch its exit status.
377		452
378	The child process is specified by the C<pid> argument (if set to C<0>, it	453	The child process is specified by the C<pid> argument (on some backends,
379	watches for any child process exit). The watcher will triggered only when	454	using C<0> watches for any child process exit, on others this will
380	the child process has finished and an exit status is available, not on	455	croak). The watcher will be triggered only when the child process has
381	any trace events (stopped/continued).	456	finished and an exit status is available, not on any trace events
		457	(stopped/continued).
382		458
383	The callback will be called with the pid and exit status (as returned by	459	The callback will be called with the pid and exit status (as returned by
384	waitpid), so unlike other watcher types, you I<can> rely on child watcher	460	waitpid), so unlike other watcher types, you I<can> rely on child watcher
385	callback arguments.	461	callback arguments.
386		462
…		…
391		467
392	There is a slight catch to child watchers, however: you usually start them	468	There is a slight catch to child watchers, however: you usually start them
393	I<after> the child process was created, and this means the process could	469	I<after> the child process was created, and this means the process could
394	have exited already (and no SIGCHLD will be sent anymore).	470	have exited already (and no SIGCHLD will be sent anymore).
395		471
396	Not all event models handle this correctly (POE doesn't), but even for	472	Not all event models handle this correctly (neither POE nor IO::Async do,
		473	see their AnyEvent::Impl manpages for details), but even for event models
397	event models that I<do> handle this correctly, they usually need to be	474	that I<do> handle this correctly, they usually need to be loaded before
398	loaded before the process exits (i.e. before you fork in the first place).	475	the process exits (i.e. before you fork in the first place). AnyEvent's
		476	pure perl event loop handles all cases correctly regardless of when you
		477	start the watcher.
399		478
400	This means you cannot create a child watcher as the very first thing in an	479	This means you cannot create a child watcher as the very first
401	AnyEvent program, you I<have> to create at least one watcher before you	480	thing in an AnyEvent program, you I<have> to create at least one
402	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	481	watcher before you C<fork> the child (alternatively, you can call
		482	C<AnyEvent::detect>).
		483
		484	As most event loops do not support waiting for child events, they will be
		485	emulated by AnyEvent in most cases, in which the latency and race problems
		486	mentioned in the description of signal watchers apply.
403		487
404	Example: fork a process and wait for it	488	Example: fork a process and wait for it
405		489
406	my $done = AnyEvent->condvar;	490	my $done = AnyEvent->condvar;
407		491
…		…
419	# do something else, then wait for process exit	503	# do something else, then wait for process exit
420	$done->recv;	504	$done->recv;
421		505
422	=head2 IDLE WATCHERS	506	=head2 IDLE WATCHERS
423		507
424	Sometimes there is a need to do something, but it is not so important	508	$w = AnyEvent->idle (cb => <callback>);
425	to do it instantly, but only when there is nothing better to do. This
426	"nothing better to do" is usually defined to be "no other events need
427	attention by the event loop".
428		509
429	Idle watchers ideally get invoked when the event loop has nothing	510	This will repeatedly invoke the callback after the process becomes idle,
430	better to do, just before it would block the process to wait for new	511	until either the watcher is destroyed or new events have been detected.
431	events. Instead of blocking, the idle watcher is invoked.
432		512
433	Most event loops unfortunately do not really support idle watchers (only	513	Idle watchers are useful when there is a need to do something, but it
		514	is not so important (or wise) to do it instantly. The callback will be
		515	invoked only when there is "nothing better to do", which is usually
		516	defined as "all outstanding events have been handled and no new events
		517	have been detected". That means that idle watchers ideally get invoked
		518	when the event loop has just polled for new events but none have been
		519	detected. Instead of blocking to wait for more events, the idle watchers
		520	will be invoked.
		521
		522	Unfortunately, most event loops do not really support idle watchers (only
434	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent	523	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
435	will simply call the callback "from time to time".	524	will simply call the callback "from time to time".
436		525
437	Example: read lines from STDIN, but only process them when the	526	Example: read lines from STDIN, but only process them when the
438	program is otherwise idle:	527	program is otherwise idle:
…		…
454	});	543	});
455	});	544	});
456		545
457	=head2 CONDITION VARIABLES	546	=head2 CONDITION VARIABLES
458		547
		548	$cv = AnyEvent->condvar;
		549
		550	$cv->send (<list>);
		551	my @res = $cv->recv;
		552
459	If you are familiar with some event loops you will know that all of them	553	If you are familiar with some event loops you will know that all of them
460	require you to run some blocking "loop", "run" or similar function that	554	require you to run some blocking "loop", "run" or similar function that
461	will actively watch for new events and call your callbacks.	555	will actively watch for new events and call your callbacks.
462		556
463	AnyEvent is different, it expects somebody else to run the event loop and	557	AnyEvent is slightly different: it expects somebody else to run the event
464	will only block when necessary (usually when told by the user).	558	loop and will only block when necessary (usually when told by the user).
465		559
466	The instrument to do that is called a "condition variable", so called	560	The tool to do that is called a "condition variable", so called because
467	because they represent a condition that must become true.	561	they represent a condition that must become true.
		562
		563	Now is probably a good time to look at the examples further below.
468		564
469	Condition variables can be created by calling the C<< AnyEvent->condvar	565	Condition variables can be created by calling the C<< AnyEvent->condvar
470	>> method, usually without arguments. The only argument pair allowed is	566	>> method, usually without arguments. The only argument pair allowed is
471
472	C<cb>, which specifies a callback to be called when the condition variable	567	C<cb>, which specifies a callback to be called when the condition variable
473	becomes true, with the condition variable as the first argument (but not	568	becomes true, with the condition variable as the first argument (but not
474	the results).	569	the results).
475		570
476	After creation, the condition variable is "false" until it becomes "true"	571	After creation, the condition variable is "false" until it becomes "true"
477	by calling the C<send> method (or calling the condition variable as if it	572	by calling the C<send> method (or calling the condition variable as if it
478	were a callback, read about the caveats in the description for the C<<	573	were a callback, read about the caveats in the description for the C<<
479	->send >> method).	574	->send >> method).
480		575
481	Condition variables are similar to callbacks, except that you can	576	Since condition variables are the most complex part of the AnyEvent API, here are
482	optionally wait for them. They can also be called merge points - points	577	some different mental models of what they are - pick the ones you can connect to:
483	in time where multiple outstanding events have been processed. And yet	578
484	another way to call them is transactions - each condition variable can be	579	=over 4
485	used to represent a transaction, which finishes at some point and delivers	580
486	a result.	581	=item * Condition variables are like callbacks - you can call them (and pass them instead
		582	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		583
		584	=item * Condition variables are signals - one side can emit or send them,
		585	the other side can wait for them, or install a handler that is called when
		586	the signal fires.
		587
		588	=item * Condition variables are like "Merge Points" - points in your program
		589	where you merge multiple independent results/control flows into one.
		590
		591	=item * Condition variables represent a transaction - functions that start
		592	some kind of transaction can return them, leaving the caller the choice
		593	between waiting in a blocking fashion, or setting a callback.
		594
		595	=item * Condition variables represent future values, or promises to deliver
		596	some result, long before the result is available.
		597
		598	=back
487		599
488	Condition variables are very useful to signal that something has finished,	600	Condition variables are very useful to signal that something has finished,
489	for example, if you write a module that does asynchronous http requests,	601	for example, if you write a module that does asynchronous http requests,
490	then a condition variable would be the ideal candidate to signal the	602	then a condition variable would be the ideal candidate to signal the
491	availability of results. The user can either act when the callback is	603	availability of results. The user can either act when the callback is
…		…
504		616
505	Condition variables are represented by hash refs in perl, and the keys	617	Condition variables are represented by hash refs in perl, and the keys
506	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	618	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
507	easy (it is often useful to build your own transaction class on top of	619	easy (it is often useful to build your own transaction class on top of
508	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	620	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
509	it's C<new> method in your own C<new> method.	621	its C<new> method in your own C<new> method.
510		622
511	There are two "sides" to a condition variable - the "producer side" which	623	There are two "sides" to a condition variable - the "producer side" which
512	eventually calls C<< -> send >>, and the "consumer side", which waits	624	eventually calls C<< -> send >>, and the "consumer side", which waits
513	for the send to occur.	625	for the send to occur.
514		626
515	Example: wait for a timer.	627	Example: wait for a timer.
516		628
517	# wait till the result is ready	629	# condition: "wait till the timer is fired"
518	my $result_ready = AnyEvent->condvar;	630	my $timer_fired = AnyEvent->condvar;
519		631
520	# do something such as adding a timer	632	# create the timer - we could wait for, say
521	# or socket watcher the calls $result_ready->send	633	# a handle becomign ready, or even an
522	# when the "result" is ready.	634	# AnyEvent::HTTP request to finish, but
523	# in this case, we simply use a timer:	635	# in this case, we simply use a timer:
524	my $w = AnyEvent->timer (	636	my $w = AnyEvent->timer (
525	after => 1,	637	after => 1,
526	cb => sub { $result_ready->send },	638	cb => sub { $timer_fired->send },
527	);	639	);
528		640
529	# this "blocks" (while handling events) till the callback	641	# this "blocks" (while handling events) till the callback
530	# calls send	642	# calls ->send
531	$result_ready->recv;	643	$timer_fired->recv;
532		644
533	Example: wait for a timer, but take advantage of the fact that	645	Example: wait for a timer, but take advantage of the fact that condition
534	condition variables are also code references.	646	variables are also callable directly.
535		647
536	my $done = AnyEvent->condvar;	648	my $done = AnyEvent->condvar;
537	my $delay = AnyEvent->timer (after => 5, cb => $done);	649	my $delay = AnyEvent->timer (after => 5, cb => $done);
538	$done->recv;	650	$done->recv;
539		651
…		…
545		657
546	...	658	...
547		659
548	my @info = $couchdb->info->recv;	660	my @info = $couchdb->info->recv;
549		661
550	And this is how you would just ste a callback to be called whenever the	662	And this is how you would just set a callback to be called whenever the
551	results are available:	663	results are available:
552		664
553	$couchdb->info->cb (sub {	665	$couchdb->info->cb (sub {
554	my @info = $_[0]->recv;	666	my @info = $_[0]->recv;
555	});	667	});
…		…
573	immediately from within send.	685	immediately from within send.
574		686
575	Any arguments passed to the C<send> call will be returned by all	687	Any arguments passed to the C<send> call will be returned by all
576	future C<< ->recv >> calls.	688	future C<< ->recv >> calls.
577		689
578	Condition variables are overloaded so one can call them directly	690	Condition variables are overloaded so one can call them directly (as if
579	(as a code reference). Calling them directly is the same as calling	691	they were a code reference). Calling them directly is the same as calling
580	C<send>. Note, however, that many C-based event loops do not handle	692	C<send>.
581	overloading, so as tempting as it may be, passing a condition variable
582	instead of a callback does not work. Both the pure perl and EV loops
583	support overloading, however, as well as all functions that use perl to
584	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
585	example).
586		693
587	=item $cv->croak ($error)	694	=item $cv->croak ($error)
588		695
589	Similar to send, but causes all call's to C<< ->recv >> to invoke	696	Similar to send, but causes all calls to C<< ->recv >> to invoke
590	C<Carp::croak> with the given error message/object/scalar.	697	C<Carp::croak> with the given error message/object/scalar.
591		698
592	This can be used to signal any errors to the condition variable	699	This can be used to signal any errors to the condition variable
593	user/consumer.	700	user/consumer. Doing it this way instead of calling C<croak> directly
		701	delays the error detection, but has the overwhelming advantage that it
		702	diagnoses the error at the place where the result is expected, and not
		703	deep in some event callback with no connection to the actual code causing
		704	the problem.
594		705
595	=item $cv->begin ([group callback])	706	=item $cv->begin ([group callback])
596		707
597	=item $cv->end	708	=item $cv->end
598
599	These two methods are EXPERIMENTAL and MIGHT CHANGE.
600		709
601	These two methods can be used to combine many transactions/events into	710	These two methods can be used to combine many transactions/events into
602	one. For example, a function that pings many hosts in parallel might want	711	one. For example, a function that pings many hosts in parallel might want
603	to use a condition variable for the whole process.	712	to use a condition variable for the whole process.
604		713
605	Every call to C<< ->begin >> will increment a counter, and every call to	714	Every call to C<< ->begin >> will increment a counter, and every call to
606	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	715	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
607	>>, the (last) callback passed to C<begin> will be executed. That callback	716	>>, the (last) callback passed to C<begin> will be executed, passing the
608	is I<supposed> to call C<< ->send >>, but that is not required. If no	717	condvar as first argument. That callback is I<supposed> to call C<< ->send
609	callback was set, C<send> will be called without any arguments.	718	>>, but that is not required. If no group callback was set, C<send> will
		719	be called without any arguments.
610		720
611	Let's clarify this with the ping example:	721	You can think of C<< $cv->send >> giving you an OR condition (one call
		722	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		723	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		724
		725	Let's start with a simple example: you have two I/O watchers (for example,
		726	STDOUT and STDERR for a program), and you want to wait for both streams to
		727	close before activating a condvar:
612		728
613	my $cv = AnyEvent->condvar;	729	my $cv = AnyEvent->condvar;
614		730
		731	$cv->begin; # first watcher
		732	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		733	defined sysread $fh1, my $buf, 4096
		734	or $cv->end;
		735	});
		736
		737	$cv->begin; # second watcher
		738	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		739	defined sysread $fh2, my $buf, 4096
		740	or $cv->end;
		741	});
		742
		743	$cv->recv;
		744
		745	This works because for every event source (EOF on file handle), there is
		746	one call to C<begin>, so the condvar waits for all calls to C<end> before
		747	sending.
		748
		749	The ping example mentioned above is slightly more complicated, as the
		750	there are results to be passwd back, and the number of tasks that are
		751	begun can potentially be zero:
		752
		753	my $cv = AnyEvent->condvar;
		754
615	my %result;	755	my %result;
616	$cv->begin (sub { $cv->send (\%result) });	756	$cv->begin (sub { shift->send (\%result) });
617		757
618	for my $host (@list_of_hosts) {	758	for my $host (@list_of_hosts) {
619	$cv->begin;	759	$cv->begin;
620	ping_host_then_call_callback $host, sub {	760	ping_host_then_call_callback $host, sub {
621	$result{$host} = ...;	761	$result{$host} = ...;
…		…
636	loop, which serves two important purposes: first, it sets the callback	776	loop, which serves two important purposes: first, it sets the callback
637	to be called once the counter reaches C<0>, and second, it ensures that	777	to be called once the counter reaches C<0>, and second, it ensures that
638	C<send> is called even when C<no> hosts are being pinged (the loop	778	C<send> is called even when C<no> hosts are being pinged (the loop
639	doesn't execute once).	779	doesn't execute once).
640		780
641	This is the general pattern when you "fan out" into multiple subrequests:	781	This is the general pattern when you "fan out" into multiple (but
642	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	782	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
643	is called at least once, and then, for each subrequest you start, call	783	the callback and ensure C<end> is called at least once, and then, for each
644	C<begin> and for each subrequest you finish, call C<end>.	784	subrequest you start, call C<begin> and for each subrequest you finish,
		785	call C<end>.
645		786
646	=back	787	=back
647		788
648	=head3 METHODS FOR CONSUMERS	789	=head3 METHODS FOR CONSUMERS
649		790
…		…
653	=over 4	794	=over 4
654		795
655	=item $cv->recv	796	=item $cv->recv
656		797
657	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	798	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
658	>> methods have been called on c<$cv>, while servicing other watchers	799	>> methods have been called on C<$cv>, while servicing other watchers
659	normally.	800	normally.
660		801
661	You can only wait once on a condition - additional calls are valid but	802	You can only wait once on a condition - additional calls are valid but
662	will return immediately.	803	will return immediately.
663		804
…		…
665	function will call C<croak>.	806	function will call C<croak>.
666		807
667	In list context, all parameters passed to C<send> will be returned,	808	In list context, all parameters passed to C<send> will be returned,
668	in scalar context only the first one will be returned.	809	in scalar context only the first one will be returned.
669		810
		811	Note that doing a blocking wait in a callback is not supported by any
		812	event loop, that is, recursive invocation of a blocking C<< ->recv
		813	>> is not allowed, and the C<recv> call will C<croak> if such a
		814	condition is detected. This condition can be slightly loosened by using
		815	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		816	any thread that doesn't run the event loop itself.
		817
670	Not all event models support a blocking wait - some die in that case	818	Not all event models support a blocking wait - some die in that case
671	(programs might want to do that to stay interactive), so I<if you are	819	(programs might want to do that to stay interactive), so I<if you are
672	using this from a module, never require a blocking wait>, but let the	820	using this from a module, never require a blocking wait>. Instead, let the
673	caller decide whether the call will block or not (for example, by coupling	821	caller decide whether the call will block or not (for example, by coupling
674	condition variables with some kind of request results and supporting	822	condition variables with some kind of request results and supporting
675	callbacks so the caller knows that getting the result will not block,	823	callbacks so the caller knows that getting the result will not block,
676	while still supporting blocking waits if the caller so desires).	824	while still supporting blocking waits if the caller so desires).
677		825
678	Another reason I<never> to C<< ->recv >> in a module is that you cannot
679	sensibly have two C<< ->recv >>'s in parallel, as that would require
680	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
681	can supply.
682
683	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
684	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
685	versions and also integrates coroutines into AnyEvent, making blocking
686	C<< ->recv >> calls perfectly safe as long as they are done from another
687	coroutine (one that doesn't run the event loop).
688
689	You can ensure that C<< -recv >> never blocks by setting a callback and	826	You can ensure that C<< ->recv >> never blocks by setting a callback and
690	only calling C<< ->recv >> from within that callback (or at a later	827	only calling C<< ->recv >> from within that callback (or at a later
691	time). This will work even when the event loop does not support blocking	828	time). This will work even when the event loop does not support blocking
692	waits otherwise.	829	waits otherwise.
693		830
694	=item $bool = $cv->ready	831	=item $bool = $cv->ready
…		…
700		837
701	This is a mutator function that returns the callback set and optionally	838	This is a mutator function that returns the callback set and optionally
702	replaces it before doing so.	839	replaces it before doing so.
703		840
704	The callback will be called when the condition becomes "true", i.e. when	841	The callback will be called when the condition becomes "true", i.e. when
705	C<send> or C<croak> are called, with the only argument being the condition	842	C<send> or C<croak> are called, with the only argument being the
706	variable itself. Calling C<recv> inside the callback or at any later time	843	condition variable itself. If the condition is already true, the
707	is guaranteed not to block.	844	callback is called immediately when it is set. Calling C<recv> inside
		845	the callback or at any later time is guaranteed not to block.
708		846
709	=back	847	=back
710		848
		849	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		850
		851	The available backend classes are (every class has its own manpage):
		852
		853	=over 4
		854
		855	=item Backends that are autoprobed when no other event loop can be found.
		856
		857	EV is the preferred backend when no other event loop seems to be in
		858	use. If EV is not installed, then AnyEvent will fall back to its own
		859	pure-perl implementation, which is available everywhere as it comes with
		860	AnyEvent itself.
		861
		862	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		863	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		864
		865	=item Backends that are transparently being picked up when they are used.
		866
		867	These will be used if they are already loaded when the first watcher
		868	is created, in which case it is assumed that the application is using
		869	them. This means that AnyEvent will automatically pick the right backend
		870	when the main program loads an event module before anything starts to
		871	create watchers. Nothing special needs to be done by the main program.
		872
		873	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		874	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		875	AnyEvent::Impl::Tk based on Tk, very broken.
		876	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		877	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		878	AnyEvent::Impl::Irssi used when running within irssi.
		879
		880	=item Backends with special needs.
		881
		882	Qt requires the Qt::Application to be instantiated first, but will
		883	otherwise be picked up automatically. As long as the main program
		884	instantiates the application before any AnyEvent watchers are created,
		885	everything should just work.
		886
		887	AnyEvent::Impl::Qt based on Qt.
		888
		889	Support for IO::Async can only be partial, as it is too broken and
		890	architecturally limited to even support the AnyEvent API. It also
		891	is the only event loop that needs the loop to be set explicitly, so
		892	it can only be used by a main program knowing about AnyEvent. See
		893	L<AnyEvent::Impl::IOAsync> for the gory details.
		894
		895	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		896
		897	=item Event loops that are indirectly supported via other backends.
		898
		899	Some event loops can be supported via other modules:
		900
		901	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		902
		903	B<WxWidgets> has no support for watching file handles. However, you can
		904	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		905	polls 20 times per second, which was considered to be too horrible to even
		906	consider for AnyEvent.
		907
		908	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		909	backend, so it can be supported through POE.
		910
		911	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		912	load L<POE> when detecting them, in the hope that POE will pick them up,
		913	in which case everything will be automatic.
		914
		915	=back
		916
711	=head1 GLOBAL VARIABLES AND FUNCTIONS	917	=head1 GLOBAL VARIABLES AND FUNCTIONS
712		918
		919	These are not normally required to use AnyEvent, but can be useful to
		920	write AnyEvent extension modules.
		921
713	=over 4	922	=over 4
714		923
715	=item $AnyEvent::MODEL	924	=item $AnyEvent::MODEL
716		925
717	Contains C<undef> until the first watcher is being created. Then it	926	Contains C<undef> until the first watcher is being created, before the
		927	backend has been autodetected.
		928
718	contains the event model that is being used, which is the name of the	929	Afterwards it contains the event model that is being used, which is the
719	Perl class implementing the model. This class is usually one of the	930	name of the Perl class implementing the model. This class is usually one
720	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	931	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
721	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	932	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
722		933	will be C<urxvt::anyevent>).
723	The known classes so far are:
724
725	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
726	AnyEvent::Impl::Event based on Event, second best choice.
727	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
728	AnyEvent::Impl::Glib based on Glib, third-best choice.
729	AnyEvent::Impl::Tk based on Tk, very bad choice.
730	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
731	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
732	AnyEvent::Impl::POE based on POE, not generic enough for full support.
733
734	There is no support for WxWidgets, as WxWidgets has no support for
735	watching file handles. However, you can use WxWidgets through the
736	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
737	second, which was considered to be too horrible to even consider for
738	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
739	it's adaptor.
740
741	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
742	autodetecting them.
743		934
744	=item AnyEvent::detect	935	=item AnyEvent::detect
745		936
746	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	937	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
747	if necessary. You should only call this function right before you would	938	if necessary. You should only call this function right before you would
748	have created an AnyEvent watcher anyway, that is, as late as possible at	939	have created an AnyEvent watcher anyway, that is, as late as possible at
749	runtime.	940	runtime, and not e.g. during initialisation of your module.
		941
		942	If you need to do some initialisation before AnyEvent watchers are
		943	created, use C<post_detect>.
750		944
751	=item $guard = AnyEvent::post_detect { BLOCK }	945	=item $guard = AnyEvent::post_detect { BLOCK }
752		946
753	Arranges for the code block to be executed as soon as the event model is	947	Arranges for the code block to be executed as soon as the event model is
754	autodetected (or immediately if this has already happened).	948	autodetected (or immediately if that has already happened).
		949
		950	The block will be executed I<after> the actual backend has been detected
		951	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		952	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		953	other initialisations - see the sources of L<AnyEvent::Strict> or
		954	L<AnyEvent::AIO> to see how this is used.
		955
		956	The most common usage is to create some global watchers, without forcing
		957	event module detection too early, for example, L<AnyEvent::AIO> creates
		958	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		959	avoid autodetecting the event module at load time.
755		960
756	If called in scalar or list context, then it creates and returns an object	961	If called in scalar or list context, then it creates and returns an object
757	that automatically removes the callback again when it is destroyed. See	962	that automatically removes the callback again when it is destroyed (or
		963	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
758	L<Coro::BDB> for a case where this is useful.	964	a case where this is useful.
		965
		966	Example: Create a watcher for the IO::AIO module and store it in
		967	C<$WATCHER>, but do so only do so after the event loop is initialised.
		968
		969	our WATCHER;
		970
		971	my $guard = AnyEvent::post_detect {
		972	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		973	};
		974
		975	# the ||= is important in case post_detect immediately runs the block,
		976	# as to not clobber the newly-created watcher. assigning both watcher and
		977	# post_detect guard to the same variable has the advantage of users being
		978	# able to just C<undef $WATCHER> if the watcher causes them grief.
		979
		980	$WATCHER ||= $guard;
759		981
760	=item @AnyEvent::post_detect	982	=item @AnyEvent::post_detect
761		983
762	If there are any code references in this array (you can C<push> to it	984	If there are any code references in this array (you can C<push> to it
763	before or after loading AnyEvent), then they will called directly after	985	before or after loading AnyEvent), then they will be called directly
764	the event loop has been chosen.	986	after the event loop has been chosen.
765		987
766	You should check C<$AnyEvent::MODEL> before adding to this array, though:	988	You should check C<$AnyEvent::MODEL> before adding to this array, though:
767	if it contains a true value then the event loop has already been detected,	989	if it is defined then the event loop has already been detected, and the
768	and the array will be ignored.	990	array will be ignored.
769		991
770	Best use C<AnyEvent::post_detect { BLOCK }> instead.	992	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		993	it, as it takes care of these details.
		994
		995	This variable is mainly useful for modules that can do something useful
		996	when AnyEvent is used and thus want to know when it is initialised, but do
		997	not need to even load it by default. This array provides the means to hook
		998	into AnyEvent passively, without loading it.
		999
		1000	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1001	together, you could put this into Coro (this is the actual code used by
		1002	Coro to accomplish this):
		1003
		1004	if (defined $AnyEvent::MODEL) {
		1005	# AnyEvent already initialised, so load Coro::AnyEvent
		1006	require Coro::AnyEvent;
		1007	} else {
		1008	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1009	# as soon as it is
		1010	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1011	}
771		1012
772	=back	1013	=back
773		1014
774	=head1 WHAT TO DO IN A MODULE	1015	=head1 WHAT TO DO IN A MODULE
775		1016
…		…
786	because it will stall the whole program, and the whole point of using	1027	because it will stall the whole program, and the whole point of using
787	events is to stay interactive.	1028	events is to stay interactive.
788		1029
789	It is fine, however, to call C<< ->recv >> when the user of your module	1030	It is fine, however, to call C<< ->recv >> when the user of your module
790	requests it (i.e. if you create a http request object ad have a method	1031	requests it (i.e. if you create a http request object ad have a method
791	called C<results> that returns the results, it should call C<< ->recv >>	1032	called C<results> that returns the results, it may call C<< ->recv >>
792	freely, as the user of your module knows what she is doing. always).	1033	freely, as the user of your module knows what she is doing. Always).
793		1034
794	=head1 WHAT TO DO IN THE MAIN PROGRAM	1035	=head1 WHAT TO DO IN THE MAIN PROGRAM
795		1036
796	There will always be a single main program - the only place that should	1037	There will always be a single main program - the only place that should
797	dictate which event model to use.	1038	dictate which event model to use.
798		1039
799	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1040	If the program is not event-based, it need not do anything special, even
800	do anything special (it does not need to be event-based) and let AnyEvent	1041	when it depends on a module that uses an AnyEvent. If the program itself
801	decide which implementation to chose if some module relies on it.	1042	uses AnyEvent, but does not care which event loop is used, all it needs
		1043	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1044	available loop implementation.
802		1045
803	If the main program relies on a specific event model - for example, in	1046	If the main program relies on a specific event model - for example, in
804	Gtk2 programs you have to rely on the Glib module - you should load the	1047	Gtk2 programs you have to rely on the Glib module - you should load the
805	event module before loading AnyEvent or any module that uses it: generally	1048	event module before loading AnyEvent or any module that uses it: generally
806	speaking, you should load it as early as possible. The reason is that	1049	speaking, you should load it as early as possible. The reason is that
807	modules might create watchers when they are loaded, and AnyEvent will	1050	modules might create watchers when they are loaded, and AnyEvent will
808	decide on the event model to use as soon as it creates watchers, and it	1051	decide on the event model to use as soon as it creates watchers, and it
809	might chose the wrong one unless you load the correct one yourself.	1052	might choose the wrong one unless you load the correct one yourself.
810		1053
811	You can chose to use a pure-perl implementation by loading the	1054	You can chose to use a pure-perl implementation by loading the
812	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1055	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
813	everywhere, but letting AnyEvent chose the model is generally better.	1056	everywhere, but letting AnyEvent chose the model is generally better.
814		1057
…		…
830		1073
831		1074
832	=head1 OTHER MODULES	1075	=head1 OTHER MODULES
833		1076
834	The following is a non-exhaustive list of additional modules that use	1077	The following is a non-exhaustive list of additional modules that use
835	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1078	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
836	in the same program. Some of the modules come with AnyEvent, some are	1079	modules and other event loops in the same program. Some of the modules
837	available via CPAN.	1080	come as part of AnyEvent, the others are available via CPAN.
838		1081
839	=over 4	1082	=over 4
840		1083
841	=item L<AnyEvent::Util>	1084	=item L<AnyEvent::Util>
842		1085
843	Contains various utility functions that replace often-used but blocking	1086	Contains various utility functions that replace often-used blocking
844	functions such as C<inet_aton> by event-/callback-based versions.	1087	functions such as C<inet_aton> with event/callback-based versions.
845		1088
846	=item L<AnyEvent::Socket>	1089	=item L<AnyEvent::Socket>
847		1090
848	Provides various utility functions for (internet protocol) sockets,	1091	Provides various utility functions for (internet protocol) sockets,
849	addresses and name resolution. Also functions to create non-blocking tcp	1092	addresses and name resolution. Also functions to create non-blocking tcp
…		…
851		1094
852	=item L<AnyEvent::Handle>	1095	=item L<AnyEvent::Handle>
853		1096
854	Provide read and write buffers, manages watchers for reads and writes,	1097	Provide read and write buffers, manages watchers for reads and writes,
855	supports raw and formatted I/O, I/O queued and fully transparent and	1098	supports raw and formatted I/O, I/O queued and fully transparent and
856	non-blocking SSL/TLS.	1099	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
857		1100
858	=item L<AnyEvent::DNS>	1101	=item L<AnyEvent::DNS>
859		1102
860	Provides rich asynchronous DNS resolver capabilities.	1103	Provides rich asynchronous DNS resolver capabilities.
861		1104
		1105	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1106
		1107	Implement event-based interfaces to the protocols of the same name (for
		1108	the curious, IGS is the International Go Server and FCP is the Freenet
		1109	Client Protocol).
		1110
		1111	=item L<AnyEvent::Handle::UDP>
		1112
		1113	Here be danger!
		1114
		1115	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1116	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1117	its use of a stream-based API with a protocol that isn't streamable, that
		1118	the only way to improve it is to delete it.
		1119
		1120	It features data corruption (but typically only under load) and general
		1121	confusion. On top, the author is not only clueless about UDP but also
		1122	fact-resistant - some gems of his understanding: "connect doesn't work
		1123	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1124	packets", "I don't need to implement proper error checking as UDP doesn't
		1125	support error checking" and so on - he doesn't even understand what's
		1126	wrong with his module when it is explained to him.
		1127
862	=item L<AnyEvent::HTTP>	1128	=item L<AnyEvent::DBI>
863		1129
864	A simple-to-use HTTP library that is capable of making a lot of concurrent	1130	Executes L<DBI> requests asynchronously in a proxy process for you,
865	HTTP requests.	1131	notifying you in an event-based way when the operation is finished.
		1132
		1133	=item L<AnyEvent::AIO>
		1134
		1135	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1136	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1137	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1138	file I/O, and much more.
866		1139
867	=item L<AnyEvent::HTTPD>	1140	=item L<AnyEvent::HTTPD>
868		1141
869	Provides a simple web application server framework.	1142	A simple embedded webserver.
870		1143
871	=item L<AnyEvent::FastPing>	1144	=item L<AnyEvent::FastPing>
872		1145
873	The fastest ping in the west.	1146	The fastest ping in the west.
874		1147
875	=item L<AnyEvent::DBI>
876
877	Executes L<DBI> requests asynchronously in a proxy process.
878
879	=item L<AnyEvent::AIO>
880
881	Truly asynchronous I/O, should be in the toolbox of every event
882	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
883	together.
884
885	=item L<AnyEvent::BDB>
886
887	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
888	L<BDB> and AnyEvent together.
889
890	=item L<AnyEvent::GPSD>
891
892	A non-blocking interface to gpsd, a daemon delivering GPS information.
893
894	=item L<AnyEvent::IGS>
895
896	A non-blocking interface to the Internet Go Server protocol (used by
897	L<App::IGS>).
898
899	=item L<AnyEvent::IRC>
900
901	AnyEvent based IRC client module family (replacing the older Net::IRC3).
902
903	=item L<Net::XMPP2>
904
905	AnyEvent based XMPP (Jabber protocol) module family.
906
907	=item L<Net::FCP>
908
909	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
910	of AnyEvent.
911
912	=item L<Event::ExecFlow>
913
914	High level API for event-based execution flow control.
915
916	=item L<Coro>	1148	=item L<Coro>
917		1149
918	Has special support for AnyEvent via L<Coro::AnyEvent>.	1150	Has special support for AnyEvent via L<Coro::AnyEvent>.
919		1151
920	=item L<IO::Lambda>
921
922	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
923
924	=back	1152	=back
925		1153
926	=cut	1154	=cut
927		1155
928	package AnyEvent;	1156	package AnyEvent;
929		1157
930	no warnings;	1158	# basically a tuned-down version of common::sense
931	use strict qw(vars subs);	1159	sub common_sense {
		1160	# from common:.sense 1.0
		1161	${^WARNING_BITS} = "\xfc\x3f\x33\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x00";
		1162	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1163	$^H |= 0x00000600;
		1164	}
932		1165
		1166	BEGIN { AnyEvent::common_sense }
		1167
933	use Carp;	1168	use Carp ();
934		1169
935	our $VERSION = 4.4;	1170	our $VERSION = '5.271';
936	our $MODEL;	1171	our $MODEL;
937		1172
938	our $AUTOLOAD;	1173	our $AUTOLOAD;
939	our @ISA;	1174	our @ISA;
940		1175
941	our @REGISTRY;	1176	our @REGISTRY;
942		1177
943	our $WIN32;	1178	our $VERBOSE;
944		1179
945	BEGIN {	1180	BEGIN {
946	my $win32 = ! ! ($^O =~ /mswin32/i);	1181	require "AnyEvent/constants.pl";
947	eval "sub WIN32(){ $win32 }";
948	}
949		1182
		1183	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1184
		1185	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1186	if ${^TAINT};
		1187
950	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1188	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1189
		1190	}
		1191
		1192	our $MAX_SIGNAL_LATENCY = 10;
951		1193
952	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1194	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
953		1195
954	{	1196	{
955	my $idx;	1197	my $idx;
…		…
957	for reverse split /\s*,\s*/,	1199	for reverse split /\s*,\s*/,
958	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1200	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
959	}	1201	}
960		1202
961	my @models = (	1203	my @models = (
962	[EV:: => AnyEvent::Impl::EV::],	1204	[EV:: => AnyEvent::Impl::EV:: , 1],
963	[Event:: => AnyEvent::Impl::Event::],
964	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1205	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
965	# everything below here will not be autoprobed	1206	# everything below here will not (normally) be autoprobed
966	# as the pureperl backend should work everywhere	1207	# as the pureperl backend should work everywhere
967	# and is usually faster	1208	# and is usually faster
		1209	[Event:: => AnyEvent::Impl::Event::, 1],
		1210	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1211	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1212	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
968	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1213	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
969	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
970	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
971	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1214	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
972	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1215	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
973	[Wx:: => AnyEvent::Impl::POE::],	1216	[Wx:: => AnyEvent::Impl::POE::],
974	[Prima:: => AnyEvent::Impl::POE::],	1217	[Prima:: => AnyEvent::Impl::POE::],
		1218	# IO::Async is just too broken - we would need workarounds for its
		1219	# byzantine signal and broken child handling, among others.
		1220	# IO::Async is rather hard to detect, as it doesn't have any
		1221	# obvious default class.
		1222	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1223	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1224	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1225	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
975	);	1226	);
976		1227
977	our %method = map +($_ => 1),	1228	our %method = map +($_ => 1),
978	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1229	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
979		1230
980	our @post_detect;	1231	our @post_detect;
981		1232
982	sub post_detect(&) {	1233	sub post_detect(&) {
983	my ($cb) = @_;	1234	my ($cb) = @_;
984		1235
985	if ($MODEL) {
986	$cb->();
987
988	1
989	} else {
990	push @post_detect, $cb;	1236	push @post_detect, $cb;
991		1237
992	defined wantarray	1238	defined wantarray
993	? bless \$cb, "AnyEvent::Util::postdetect"	1239	? bless \$cb, "AnyEvent::Util::postdetect"
994	: ()	1240	: ()
995	}
996	}	1241	}
997		1242
998	sub AnyEvent::Util::postdetect::DESTROY {	1243	sub AnyEvent::Util::postdetect::DESTROY {
999	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1244	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1000	}	1245	}
1001		1246
1002	sub detect() {	1247	sub detect() {
		1248	# free some memory
		1249	*detect = sub () { $MODEL };
		1250
		1251	local $!; # for good measure
		1252	local $SIG{__DIE__};
		1253
		1254	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1255	my $model = "AnyEvent::Impl::$1";
		1256	if (eval "require $model") {
		1257	$MODEL = $model;
		1258	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
		1259	} else {
		1260	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
		1261	}
		1262	}
		1263
		1264	# check for already loaded models
1003	unless ($MODEL) {	1265	unless ($MODEL) {
1004	no strict 'refs';	1266	for (@REGISTRY, @models) {
1005	local $SIG{__DIE__};	1267	my ($package, $model) = @$_;
1006		1268	if (${"$package\::VERSION"} > 0) {
1007	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1008	my $model = "AnyEvent::Impl::$1";
1009	if (eval "require $model") {	1269	if (eval "require $model") {
1010	$MODEL = $model;	1270	$MODEL = $model;
1011	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1271	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1012	} else {	1272	last;
1013	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1273	}
1014	}	1274	}
1015	}	1275	}
1016		1276
1017	# check for already loaded models
1018	unless ($MODEL) {	1277	unless ($MODEL) {
		1278	# try to autoload a model
1019	for (@REGISTRY, @models) {	1279	for (@REGISTRY, @models) {
1020	my ($package, $model) = @$_;	1280	my ($package, $model, $autoload) = @$_;
		1281	if (
		1282	$autoload
		1283	and eval "require $package"
1021	if (${"$package\::VERSION"} > 0) {	1284	and ${"$package\::VERSION"} > 0
1022	if (eval "require $model") {	1285	and eval "require $model"
		1286	) {
1023	$MODEL = $model;	1287	$MODEL = $model;
1024	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1288	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1025	last;	1289	last;
1026	}
1027	}	1290	}
1028	}	1291	}
1029		1292
1030	unless ($MODEL) {
1031	# try to load a model
1032
1033	for (@REGISTRY, @models) {
1034	my ($package, $model) = @$_;
1035	if (eval "require $package"
1036	and ${"$package\::VERSION"} > 0
1037	and eval "require $model") {
1038	$MODEL = $model;
1039	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
1040	last;
1041	}
1042	}
1043
1044	$MODEL	1293	$MODEL
1045	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";	1294	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
1046	}
1047	}	1295	}
1048
1049	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1050
1051	unshift @ISA, $MODEL;
1052
1053	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1054
1055	(shift @post_detect)->() while @post_detect;
1056	}	1296	}
		1297
		1298	@models = (); # free probe data
		1299
		1300	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1301	unshift @ISA, $MODEL;
		1302
		1303	# now nuke some methods that are overriden by the backend.
		1304	# SUPER is not allowed.
		1305	for (qw(time signal child idle)) {
		1306	undef &{"AnyEvent::Base::$_"}
		1307	if defined &{"$MODEL\::$_"};
		1308	}
		1309
		1310	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1311
		1312	(shift @post_detect)->() while @post_detect;
		1313
		1314	*post_detect = sub(&) {
		1315	shift->();
		1316
		1317	undef
		1318	};
1057		1319
1058	$MODEL	1320	$MODEL
1059	}	1321	}
1060		1322
1061	sub AUTOLOAD {	1323	sub AUTOLOAD {
1062	(my $func = $AUTOLOAD) =~ s/.*://;	1324	(my $func = $AUTOLOAD) =~ s/.*://;
1063		1325
1064	$method{$func}	1326	$method{$func}
1065	or croak "$func: not a valid method for AnyEvent objects";	1327	or Carp::croak "$func: not a valid AnyEvent class method";
1066		1328
1067	detect unless $MODEL;	1329	detect;
1068		1330
1069	my $class = shift;	1331	my $class = shift;
1070	$class->$func (@_);	1332	$class->$func (@_);
1071	}	1333	}
1072		1334
1073	# utility function to dup a filehandle. this is used by many backends	1335	# utility function to dup a filehandle. this is used by many backends
1074	# to support binding more than one watcher per filehandle (they usually	1336	# to support binding more than one watcher per filehandle (they usually
1075	# allow only one watcher per fd, so we dup it to get a different one).	1337	# allow only one watcher per fd, so we dup it to get a different one).
1076	sub _dupfh($$$$) {	1338	sub _dupfh($$;$$) {
1077	my ($poll, $fh, $r, $w) = @_;	1339	my ($poll, $fh, $r, $w) = @_;
1078		1340
1079	# cygwin requires the fh mode to be matching, unix doesn't	1341	# cygwin requires the fh mode to be matching, unix doesn't
1080	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1342	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1081	: $poll eq "w" ? ($w, ">")
1082	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1083		1343
1084	open my $fh2, "$mode&" . fileno $fh	1344	open my $fh2, $mode, $fh
1085	or die "cannot dup() filehandle: $!,";	1345	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1086		1346
1087	# we assume CLOEXEC is already set by perl in all important cases	1347	# we assume CLOEXEC is already set by perl in all important cases
1088		1348
1089	($fh2, $rw)	1349	($fh2, $rw)
1090	}	1350	}
1091		1351
		1352	=head1 SIMPLIFIED AE API
		1353
		1354	Starting with version 5.0, AnyEvent officially supports a second, much
		1355	simpler, API that is designed to reduce the calling, typing and memory
		1356	overhead by using function call syntax and a fixed number of parameters.
		1357
		1358	See the L<AE> manpage for details.
		1359
		1360	=cut
		1361
		1362	package AE;
		1363
		1364	our $VERSION = $AnyEvent::VERSION;
		1365
		1366	# fall back to the main API by default - backends and AnyEvent::Base
		1367	# implementations can overwrite these.
		1368
		1369	sub io($$$) {
		1370	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1371	}
		1372
		1373	sub timer($$$) {
		1374	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1375	}
		1376
		1377	sub signal($$) {
		1378	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1379	}
		1380
		1381	sub child($$) {
		1382	AnyEvent->child (pid => $_[0], cb => $_[1])
		1383	}
		1384
		1385	sub idle($) {
		1386	AnyEvent->idle (cb => $_[0])
		1387	}
		1388
		1389	sub cv(;&) {
		1390	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1391	}
		1392
		1393	sub now() {
		1394	AnyEvent->now
		1395	}
		1396
		1397	sub now_update() {
		1398	AnyEvent->now_update
		1399	}
		1400
		1401	sub time() {
		1402	AnyEvent->time
		1403	}
		1404
1092	package AnyEvent::Base;	1405	package AnyEvent::Base;
1093		1406
1094	# default implementations for many methods	1407	# default implementations for many methods
1095		1408
1096	BEGIN {	1409	sub time {
		1410	eval q{ # poor man's autoloading {}
		1411	# probe for availability of Time::HiRes
1097	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1412	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1413	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1098	*_time = \&Time::HiRes::time;	1414	*AE::time = \&Time::HiRes::time;
1099	# if (eval "use POSIX (); (POSIX::times())...	1415	# if (eval "use POSIX (); (POSIX::times())...
1100	} else {	1416	} else {
		1417	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1101	*_time = sub { time }; # epic fail	1418	*AE::time = sub (){ time }; # epic fail
		1419	}
		1420
		1421	*time = sub { AE::time }; # different prototypes
		1422	};
		1423	die if $@;
		1424
		1425	&time
		1426	}
		1427
		1428	*now = \&time;
		1429
		1430	sub now_update { }
		1431
		1432	# default implementation for ->condvar
		1433
		1434	sub condvar {
		1435	eval q{ # poor man's autoloading {}
		1436	*condvar = sub {
		1437	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1438	};
		1439
		1440	*AE::cv = sub (;&) {
		1441	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1442	};
		1443	};
		1444	die if $@;
		1445
		1446	&condvar
		1447	}
		1448
		1449	# default implementation for ->signal
		1450
		1451	our $HAVE_ASYNC_INTERRUPT;
		1452
		1453	sub _have_async_interrupt() {
		1454	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1455	&& eval "use Async::Interrupt 1.02 (); 1")
		1456	unless defined $HAVE_ASYNC_INTERRUPT;
		1457
		1458	$HAVE_ASYNC_INTERRUPT
		1459	}
		1460
		1461	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1462	our (%SIG_ASY, %SIG_ASY_W);
		1463	our ($SIG_COUNT, $SIG_TW);
		1464
		1465	# install a dummy wakeup watcher to reduce signal catching latency
		1466	# used by Impls
		1467	sub _sig_add() {
		1468	unless ($SIG_COUNT++) {
		1469	# try to align timer on a full-second boundary, if possible
		1470	my $NOW = AE::now;
		1471
		1472	$SIG_TW = AE::timer
		1473	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1474	$MAX_SIGNAL_LATENCY,
		1475	sub { } # just for the PERL_ASYNC_CHECK
		1476	;
1102	}	1477	}
1103	}	1478	}
1104		1479
1105	sub time { _time }	1480	sub _sig_del {
1106	sub now { _time }	1481	undef $SIG_TW
1107	sub now_update { }	1482	unless --$SIG_COUNT;
1108
1109	# default implementation for ->condvar
1110
1111	sub condvar {
1112	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1113	}	1483	}
1114		1484
1115	# default implementation for ->signal	1485	our $_sig_name_init; $_sig_name_init = sub {
		1486	eval q{ # poor man's autoloading {}
		1487	undef $_sig_name_init;
1116		1488
1117	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1489	if (_have_async_interrupt) {
		1490	*sig2num = \&Async::Interrupt::sig2num;
		1491	*sig2name = \&Async::Interrupt::sig2name;
		1492	} else {
		1493	require Config;
1118		1494
1119	sub _signal_exec {	1495	my %signame2num;
1120	sysread $SIGPIPE_R, my $dummy, 4;	1496	@signame2num{ split ' ', $Config::Config{sig_name} }
		1497	= split ' ', $Config::Config{sig_num};
1121		1498
1122	while (%SIG_EV) {	1499	my @signum2name;
1123	for (keys %SIG_EV) {	1500	@signum2name[values %signame2num] = keys %signame2num;
1124	delete $SIG_EV{$_};	1501
1125	$_->() for values %{ $SIG_CB{$_} || {} };	1502	*sig2num = sub($) {
		1503	$_[0] > 0 ? shift : $signame2num{+shift}
		1504	};
		1505	*sig2name = sub ($) {
		1506	$_[0] > 0 ? $signum2name[+shift] : shift
		1507	};
1126	}	1508	}
1127	}	1509	};
1128	}	1510	die if $@;
		1511	};
		1512
		1513	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1514	sub sig2name($) { &$_sig_name_init; &sig2name }
1129		1515
1130	sub signal {	1516	sub signal {
1131	my (undef, %arg) = @_;	1517	eval q{ # poor man's autoloading {}
		1518	# probe for availability of Async::Interrupt
		1519	if (_have_async_interrupt) {
		1520	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1132		1521
1133	unless ($SIGPIPE_R) {	1522	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1134	require Fcntl;	1523	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1135		1524
1136	if (AnyEvent::WIN32) {
1137	require AnyEvent::Util;
1138
1139	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1140	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1141	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1142	} else {	1525	} else {
		1526	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1527
		1528	if (AnyEvent::WIN32) {
		1529	require AnyEvent::Util;
		1530
		1531	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1532	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1533	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1534	} else {
1143	pipe $SIGPIPE_R, $SIGPIPE_W;	1535	pipe $SIGPIPE_R, $SIGPIPE_W;
1144	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1536	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1145	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1537	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1538
		1539	# not strictly required, as $^F is normally 2, but let's make sure...
		1540	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1541	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1542	}
		1543
		1544	$SIGPIPE_R
		1545	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1546
		1547	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1146	}	1548	}
1147		1549
1148	$SIGPIPE_R	1550	*signal = $HAVE_ASYNC_INTERRUPT
1149	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1551	? sub {
		1552	my (undef, %arg) = @_;
1150		1553
1151	# not strictly required, as $^F is normally 2, but let's make sure...	1554	# async::interrupt
1152	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1153	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1154
1155	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1156	}
1157
1158	my $signal = uc $arg{signal}	1555	my $signal = sig2num $arg{signal};
1159	or Carp::croak "required option 'signal' is missing";
1160
1161	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1556	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1557
		1558	$SIG_ASY{$signal} ||= new Async::Interrupt
		1559	cb => sub { undef $SIG_EV{$signal} },
		1560	signal => $signal,
		1561	pipe => [$SIGPIPE_R->filenos],
		1562	pipe_autodrain => 0,
		1563	;
		1564
		1565	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1566	}
		1567	: sub {
		1568	my (undef, %arg) = @_;
		1569
		1570	# pure perl
		1571	my $signal = sig2name $arg{signal};
		1572	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1573
1162	$SIG{$signal} ||= sub {	1574	$SIG{$signal} ||= sub {
1163	local $!;	1575	local $!;
1164	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1576	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1165	undef $SIG_EV{$signal};	1577	undef $SIG_EV{$signal};
		1578	};
		1579
		1580	# can't do signal processing without introducing races in pure perl,
		1581	# so limit the signal latency.
		1582	_sig_add;
		1583
		1584	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1585	}
		1586	;
		1587
		1588	*AnyEvent::Base::signal::DESTROY = sub {
		1589	my ($signal, $cb) = @{$_[0]};
		1590
		1591	_sig_del;
		1592
		1593	delete $SIG_CB{$signal}{$cb};
		1594
		1595	$HAVE_ASYNC_INTERRUPT
		1596	? delete $SIG_ASY{$signal}
		1597	: # delete doesn't work with older perls - they then
		1598	# print weird messages, or just unconditionally exit
		1599	# instead of getting the default action.
		1600	undef $SIG{$signal}
		1601	unless keys %{ $SIG_CB{$signal} };
		1602	};
		1603
		1604	*_signal_exec = sub {
		1605	$HAVE_ASYNC_INTERRUPT
		1606	? $SIGPIPE_R->drain
		1607	: sysread $SIGPIPE_R, (my $dummy), 9;
		1608
		1609	while (%SIG_EV) {
		1610	for (keys %SIG_EV) {
		1611	delete $SIG_EV{$_};
		1612	$_->() for values %{ $SIG_CB{$_} || {} };
		1613	}
		1614	}
		1615	};
1166	};	1616	};
		1617	die if $@;
1167		1618
1168	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"	1619	&signal
1169	}
1170
1171	sub AnyEvent::Base::signal::DESTROY {
1172	my ($signal, $cb) = @{$_[0]};
1173
1174	delete $SIG_CB{$signal}{$cb};
1175
1176	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1177	}	1620	}
1178		1621
1179	# default implementation for ->child	1622	# default implementation for ->child
1180		1623
1181	our %PID_CB;	1624	our %PID_CB;
1182	our $CHLD_W;	1625	our $CHLD_W;
1183	our $CHLD_DELAY_W;	1626	our $CHLD_DELAY_W;
1184	our $PID_IDLE;
1185	our $WNOHANG;	1627	our $WNOHANG;
1186		1628
1187	sub _child_wait {	1629	# used by many Impl's
1188	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1630	sub _emit_childstatus($$) {
		1631	my (undef, $rpid, $rstatus) = @_;
		1632
		1633	$_->($rpid, $rstatus)
1189	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1634	for values %{ $PID_CB{$rpid} || {} },
1190	(values %{ $PID_CB{0} || {} });	1635	values %{ $PID_CB{0} || {} };
1191	}
1192
1193	undef $PID_IDLE;
1194	}
1195
1196	sub _sigchld {
1197	# make sure we deliver these changes "synchronous" with the event loop.
1198	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1199	undef $CHLD_DELAY_W;
1200	&_child_wait;
1201	});
1202	}	1636	}
1203		1637
1204	sub child {	1638	sub child {
		1639	eval q{ # poor man's autoloading {}
		1640	*_sigchld = sub {
		1641	my $pid;
		1642
		1643	AnyEvent->_emit_childstatus ($pid, $?)
		1644	while ($pid = waitpid -1, $WNOHANG) > 0;
		1645	};
		1646
		1647	*child = sub {
1205	my (undef, %arg) = @_;	1648	my (undef, %arg) = @_;
1206		1649
1207	defined (my $pid = $arg{pid} + 0)	1650	defined (my $pid = $arg{pid} + 0)
1208	or Carp::croak "required option 'pid' is missing";	1651	or Carp::croak "required option 'pid' is missing";
1209		1652
1210	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1653	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1211		1654
1212	unless ($WNOHANG) {	1655	# WNOHANG is almost cetrainly 1 everywhere
		1656	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1657	? 1
1213	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1658	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1214	}
1215		1659
1216	unless ($CHLD_W) {	1660	unless ($CHLD_W) {
1217	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1661	$CHLD_W = AE::signal CHLD => \&_sigchld;
1218	# child could be a zombie already, so make at least one round	1662	# child could be a zombie already, so make at least one round
1219	&_sigchld;	1663	&_sigchld;
1220	}	1664	}
1221		1665
1222	bless [$pid, $arg{cb}], "AnyEvent::Base::child"	1666	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1223	}	1667	};
1224		1668
1225	sub AnyEvent::Base::child::DESTROY {	1669	*AnyEvent::Base::child::DESTROY = sub {
1226	my ($pid, $cb) = @{$_[0]};	1670	my ($pid, $cb) = @{$_[0]};
1227		1671
1228	delete $PID_CB{$pid}{$cb};	1672	delete $PID_CB{$pid}{$cb};
1229	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1673	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1230		1674
1231	undef $CHLD_W unless keys %PID_CB;	1675	undef $CHLD_W unless keys %PID_CB;
		1676	};
		1677	};
		1678	die if $@;
		1679
		1680	&child
1232	}	1681	}
1233		1682
1234	# idle emulation is done by simply using a timer, regardless	1683	# idle emulation is done by simply using a timer, regardless
1235	# of whether the proces sis idle or not, and not letting	1684	# of whether the process is idle or not, and not letting
1236	# the callback use more than 50% of the time.	1685	# the callback use more than 50% of the time.
1237	sub idle {	1686	sub idle {
		1687	eval q{ # poor man's autoloading {}
		1688	*idle = sub {
1238	my (undef, %arg) = @_;	1689	my (undef, %arg) = @_;
1239		1690
1240	my ($cb, $w, $rcb) = $arg{cb};	1691	my ($cb, $w, $rcb) = $arg{cb};
1241		1692
1242	$rcb = sub {	1693	$rcb = sub {
1243	if ($cb) {	1694	if ($cb) {
1244	$w = _time;	1695	$w = _time;
1245	&$cb;	1696	&$cb;
1246	$w = _time - $w;	1697	$w = _time - $w;
1247		1698
1248	# never use more then 50% of the time for the idle watcher,	1699	# never use more then 50% of the time for the idle watcher,
1249	# within some limits	1700	# within some limits
1250	$w = 0.0001 if $w < 0.0001;	1701	$w = 0.0001 if $w < 0.0001;
1251	$w = 5 if $w > 5;	1702	$w = 5 if $w > 5;
1252		1703
1253	$w = AnyEvent->timer (after => $w, cb => $rcb);	1704	$w = AE::timer $w, 0, $rcb;
1254	} else {	1705	} else {
1255	# clean up...	1706	# clean up...
1256	undef $w;	1707	undef $w;
1257	undef $rcb;	1708	undef $rcb;
		1709	}
		1710	};
		1711
		1712	$w = AE::timer 0.05, 0, $rcb;
		1713
		1714	bless \\$cb, "AnyEvent::Base::idle"
1258	}	1715	};
		1716
		1717	*AnyEvent::Base::idle::DESTROY = sub {
		1718	undef $${$_[0]};
		1719	};
1259	};	1720	};
		1721	die if $@;
1260		1722
1261	$w = AnyEvent->timer (after => 0.05, cb => $rcb);	1723	&idle
1262
1263	bless \\$cb, "AnyEvent::Base::idle"
1264	}
1265
1266	sub AnyEvent::Base::idle::DESTROY {
1267	undef $${$_[0]};
1268	}	1724	}
1269		1725
1270	package AnyEvent::CondVar;	1726	package AnyEvent::CondVar;
1271		1727
1272	our @ISA = AnyEvent::CondVar::Base::;	1728	our @ISA = AnyEvent::CondVar::Base::;
1273		1729
1274	package AnyEvent::CondVar::Base;	1730	package AnyEvent::CondVar::Base;
1275		1731
1276	use overload	1732	#use overload
1277	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1733	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1278	fallback => 1;	1734	# fallback => 1;
		1735
		1736	# save 300+ kilobytes by dirtily hardcoding overloading
		1737	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1738	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1739	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1740	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1741
		1742	our $WAITING;
1279		1743
1280	sub _send {	1744	sub _send {
1281	# nop	1745	# nop
1282	}	1746	}
1283		1747
…		…
1296	sub ready {	1760	sub ready {
1297	$_[0]{_ae_sent}	1761	$_[0]{_ae_sent}
1298	}	1762	}
1299		1763
1300	sub _wait {	1764	sub _wait {
		1765	$WAITING
		1766	and !$_[0]{_ae_sent}
		1767	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1768
		1769	local $WAITING = 1;
1301	AnyEvent->one_event while !$_[0]{_ae_sent};	1770	AnyEvent->one_event while !$_[0]{_ae_sent};
1302	}	1771	}
1303		1772
1304	sub recv {	1773	sub recv {
1305	$_[0]->_wait;	1774	$_[0]->_wait;
…		…
1307	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1776	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1308	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1777	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1309	}	1778	}
1310		1779
1311	sub cb {	1780	sub cb {
1312	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1781	my $cv = shift;
		1782
		1783	@_
		1784	and $cv->{_ae_cb} = shift
		1785	and $cv->{_ae_sent}
		1786	and (delete $cv->{_ae_cb})->($cv);
		1787
1313	$_[0]{_ae_cb}	1788	$cv->{_ae_cb}
1314	}	1789	}
1315		1790
1316	sub begin {	1791	sub begin {
1317	++$_[0]{_ae_counter};	1792	++$_[0]{_ae_counter};
1318	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1793	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1346	so on.	1821	so on.
1347		1822
1348	=head1 ENVIRONMENT VARIABLES	1823	=head1 ENVIRONMENT VARIABLES
1349		1824
1350	The following environment variables are used by this module or its	1825	The following environment variables are used by this module or its
1351	submodules:	1826	submodules.
		1827
		1828	Note that AnyEvent will remove I<all> environment variables starting with
		1829	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1830	enabled.
1352		1831
1353	=over 4	1832	=over 4
1354		1833
1355	=item C<PERL_ANYEVENT_VERBOSE>	1834	=item C<PERL_ANYEVENT_VERBOSE>
1356		1835
…		…
1363	C<PERL_ANYEVENT_MODEL>.	1842	C<PERL_ANYEVENT_MODEL>.
1364		1843
1365	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1844	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1366	model it chooses.	1845	model it chooses.
1367		1846
		1847	When set to C<8> or higher, then AnyEvent will report extra information on
		1848	which optional modules it loads and how it implements certain features.
		1849
1368	=item C<PERL_ANYEVENT_STRICT>	1850	=item C<PERL_ANYEVENT_STRICT>
1369		1851
1370	AnyEvent does not do much argument checking by default, as thorough	1852	AnyEvent does not do much argument checking by default, as thorough
1371	argument checking is very costly. Setting this variable to a true value	1853	argument checking is very costly. Setting this variable to a true value
1372	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1854	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1373	check the arguments passed to most method calls. If it finds any problems	1855	check the arguments passed to most method calls. If it finds any problems,
1374	it will croak.	1856	it will croak.
1375		1857
1376	In other words, enables "strict" mode.	1858	In other words, enables "strict" mode.
1377		1859
1378	Unlike C<use strict>, it is definitely recommended ot keep it off in	1860	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1379	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1861	>>, it is definitely recommended to keep it off in production. Keeping
1380	developing programs can be very useful, however.	1862	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1863	can be very useful, however.
1381		1864
1382	=item C<PERL_ANYEVENT_MODEL>	1865	=item C<PERL_ANYEVENT_MODEL>
1383		1866
1384	This can be used to specify the event model to be used by AnyEvent, before	1867	This can be used to specify the event model to be used by AnyEvent, before
1385	auto detection and -probing kicks in. It must be a string consisting	1868	auto detection and -probing kicks in. It must be a string consisting
…		…
1428		1911
1429	=item C<PERL_ANYEVENT_MAX_FORKS>	1912	=item C<PERL_ANYEVENT_MAX_FORKS>
1430		1913
1431	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1914	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1432	will create in parallel.	1915	will create in parallel.
		1916
		1917	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1918
		1919	The default value for the C<max_outstanding> parameter for the default DNS
		1920	resolver - this is the maximum number of parallel DNS requests that are
		1921	sent to the DNS server.
		1922
		1923	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1924
		1925	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1926	configuration) in the default resolver. When set to the empty string, no
		1927	default config will be used.
		1928
		1929	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1930
		1931	When neither C<ca_file> nor C<ca_path> was specified during
		1932	L<AnyEvent::TLS> context creation, and either of these environment
		1933	variables exist, they will be used to specify CA certificate locations
		1934	instead of a system-dependent default.
		1935
		1936	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1937
		1938	When these are set to C<1>, then the respective modules are not
		1939	loaded. Mostly good for testing AnyEvent itself.
1433		1940
1434	=back	1941	=back
1435		1942
1436	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1943	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1437		1944
…		…
1495	warn "read: $input\n"; # output what has been read	2002	warn "read: $input\n"; # output what has been read
1496	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2003	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1497	},	2004	},
1498	);	2005	);
1499		2006
1500	my $time_watcher; # can only be used once
1501
1502	sub new_timer {
1503	$timer = AnyEvent->timer (after => 1, cb => sub {	2007	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1504	warn "timeout\n"; # print 'timeout' about every second	2008	warn "timeout\n"; # print 'timeout' at most every second
1505	&new_timer; # and restart the time
1506	});	2009	});
1507	}
1508
1509	new_timer; # create first timer
1510		2010
1511	$cv->recv; # wait until user enters /^q/i	2011	$cv->recv; # wait until user enters /^q/i
1512		2012
1513	=head1 REAL-WORLD EXAMPLE	2013	=head1 REAL-WORLD EXAMPLE
1514		2014
…		…
1587		2087
1588	The actual code goes further and collects all errors (C<die>s, exceptions)	2088	The actual code goes further and collects all errors (C<die>s, exceptions)
1589	that occurred during request processing. The C<result> method detects	2089	that occurred during request processing. The C<result> method detects
1590	whether an exception as thrown (it is stored inside the $txn object)	2090	whether an exception as thrown (it is stored inside the $txn object)
1591	and just throws the exception, which means connection errors and other	2091	and just throws the exception, which means connection errors and other
1592	problems get reported tot he code that tries to use the result, not in a	2092	problems get reported to the code that tries to use the result, not in a
1593	random callback.	2093	random callback.
1594		2094
1595	All of this enables the following usage styles:	2095	All of this enables the following usage styles:
1596		2096
1597	1. Blocking:	2097	1. Blocking:
…		…
1645	through AnyEvent. The benchmark creates a lot of timers (with a zero	2145	through AnyEvent. The benchmark creates a lot of timers (with a zero
1646	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2146	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1647	which it is), lets them fire exactly once and destroys them again.	2147	which it is), lets them fire exactly once and destroys them again.
1648		2148
1649	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2149	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1650	distribution.	2150	distribution. It uses the L<AE> interface, which makes a real difference
		2151	for the EV and Perl backends only.
1651		2152
1652	=head3 Explanation of the columns	2153	=head3 Explanation of the columns
1653		2154
1654	I<watcher> is the number of event watchers created/destroyed. Since	2155	I<watcher> is the number of event watchers created/destroyed. Since
1655	different event models feature vastly different performances, each event	2156	different event models feature vastly different performances, each event
…		…
1676	watcher.	2177	watcher.
1677		2178
1678	=head3 Results	2179	=head3 Results
1679		2180
1680	name watchers bytes create invoke destroy comment	2181	name watchers bytes create invoke destroy comment
1681	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2182	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1682	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2183	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1683	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2184	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1684	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2185	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1685	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2186	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1686	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2187	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2188	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2189	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1687	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2190	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1688	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2191	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1689	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2192	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1690	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2193	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1691		2194
1692	=head3 Discussion	2195	=head3 Discussion
1693		2196
1694	The benchmark does I<not> measure scalability of the event loop very	2197	The benchmark does I<not> measure scalability of the event loop very
1695	well. For example, a select-based event loop (such as the pure perl one)	2198	well. For example, a select-based event loop (such as the pure perl one)
…		…
1707	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2210	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1708	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2211	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1709	cycles with POE.	2212	cycles with POE.
1710		2213
1711	C<EV> is the sole leader regarding speed and memory use, which are both	2214	C<EV> is the sole leader regarding speed and memory use, which are both
1712	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2215	maximal/minimal, respectively. When using the L<AE> API there is zero
		2216	overhead (when going through the AnyEvent API create is about 5-6 times
		2217	slower, with other times being equal, so still uses far less memory than
1713	far less memory than any other event loop and is still faster than Event	2218	any other event loop and is still faster than Event natively).
1714	natively.
1715		2219
1716	The pure perl implementation is hit in a few sweet spots (both the	2220	The pure perl implementation is hit in a few sweet spots (both the
1717	constant timeout and the use of a single fd hit optimisations in the perl	2221	constant timeout and the use of a single fd hit optimisations in the perl
1718	interpreter and the backend itself). Nevertheless this shows that it	2222	interpreter and the backend itself). Nevertheless this shows that it
1719	adds very little overhead in itself. Like any select-based backend its	2223	adds very little overhead in itself. Like any select-based backend its
1720	performance becomes really bad with lots of file descriptors (and few of	2224	performance becomes really bad with lots of file descriptors (and few of
1721	them active), of course, but this was not subject of this benchmark.	2225	them active), of course, but this was not subject of this benchmark.
1722		2226
1723	The C<Event> module has a relatively high setup and callback invocation	2227	The C<Event> module has a relatively high setup and callback invocation
1724	cost, but overall scores in on the third place.	2228	cost, but overall scores in on the third place.
		2229
		2230	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2231	when using its pure perl backend.
1725		2232
1726	C<Glib>'s memory usage is quite a bit higher, but it features a	2233	C<Glib>'s memory usage is quite a bit higher, but it features a
1727	faster callback invocation and overall ends up in the same class as	2234	faster callback invocation and overall ends up in the same class as
1728	C<Event>. However, Glib scales extremely badly, doubling the number of	2235	C<Event>. However, Glib scales extremely badly, doubling the number of
1729	watchers increases the processing time by more than a factor of four,	2236	watchers increases the processing time by more than a factor of four,
…		…
1790	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2297	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1791	(1%) are active. This mirrors the activity of large servers with many	2298	(1%) are active. This mirrors the activity of large servers with many
1792	connections, most of which are idle at any one point in time.	2299	connections, most of which are idle at any one point in time.
1793		2300
1794	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2301	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1795	distribution.	2302	distribution. It uses the L<AE> interface, which makes a real difference
		2303	for the EV and Perl backends only.
1796		2304
1797	=head3 Explanation of the columns	2305	=head3 Explanation of the columns
1798		2306
1799	I<sockets> is the number of sockets, and twice the number of "servers" (as	2307	I<sockets> is the number of sockets, and twice the number of "servers" (as
1800	each server has a read and write socket end).	2308	each server has a read and write socket end).
…		…
1807	it to another server. This includes deleting the old timeout and creating	2315	it to another server. This includes deleting the old timeout and creating
1808	a new one that moves the timeout into the future.	2316	a new one that moves the timeout into the future.
1809		2317
1810	=head3 Results	2318	=head3 Results
1811		2319
1812	name sockets create request	2320	name sockets create request
1813	EV 20000 69.01 11.16	2321	EV 20000 62.66 7.99
1814	Perl 20000 73.32 35.87	2322	Perl 20000 68.32 32.64
1815	Event 20000 212.62 257.32	2323	IOAsync 20000 174.06 101.15 epoll
1816	Glib 20000 651.16 1896.30	2324	IOAsync 20000 174.67 610.84 poll
		2325	Event 20000 202.69 242.91
		2326	Glib 20000 557.01 1689.52
1817	POE 20000 349.67 12317.24 uses POE::Loop::Event	2327	POE 20000 341.54 12086.32 uses POE::Loop::Event
1818		2328
1819	=head3 Discussion	2329	=head3 Discussion
1820		2330
1821	This benchmark I<does> measure scalability and overall performance of the	2331	This benchmark I<does> measure scalability and overall performance of the
1822	particular event loop.	2332	particular event loop.
…		…
1824	EV is again fastest. Since it is using epoll on my system, the setup time	2334	EV is again fastest. Since it is using epoll on my system, the setup time
1825	is relatively high, though.	2335	is relatively high, though.
1826		2336
1827	Perl surprisingly comes second. It is much faster than the C-based event	2337	Perl surprisingly comes second. It is much faster than the C-based event
1828	loops Event and Glib.	2338	loops Event and Glib.
		2339
		2340	IO::Async performs very well when using its epoll backend, and still quite
		2341	good compared to Glib when using its pure perl backend.
1829		2342
1830	Event suffers from high setup time as well (look at its code and you will	2343	Event suffers from high setup time as well (look at its code and you will
1831	understand why). Callback invocation also has a high overhead compared to	2344	understand why). Callback invocation also has a high overhead compared to
1832	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2345	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1833	uses select or poll in basically all documented configurations.	2346	uses select or poll in basically all documented configurations.
…		…
1896	=item * C-based event loops perform very well with small number of	2409	=item * C-based event loops perform very well with small number of
1897	watchers, as the management overhead dominates.	2410	watchers, as the management overhead dominates.
1898		2411
1899	=back	2412	=back
1900		2413
		2414	=head2 THE IO::Lambda BENCHMARK
		2415
		2416	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2417	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2418	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2419	shouldn't come as a surprise to anybody). As such, the benchmark is
		2420	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2421	very optimal. But how would AnyEvent compare when used without the extra
		2422	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2423
		2424	The benchmark itself creates an echo-server, and then, for 500 times,
		2425	connects to the echo server, sends a line, waits for the reply, and then
		2426	creates the next connection. This is a rather bad benchmark, as it doesn't
		2427	test the efficiency of the framework or much non-blocking I/O, but it is a
		2428	benchmark nevertheless.
		2429
		2430	name runtime
		2431	Lambda/select 0.330 sec
		2432	+ optimized 0.122 sec
		2433	Lambda/AnyEvent 0.327 sec
		2434	+ optimized 0.138 sec
		2435	Raw sockets/select 0.077 sec
		2436	POE/select, components 0.662 sec
		2437	POE/select, raw sockets 0.226 sec
		2438	POE/select, optimized 0.404 sec
		2439
		2440	AnyEvent/select/nb 0.085 sec
		2441	AnyEvent/EV/nb 0.068 sec
		2442	+state machine 0.134 sec
		2443
		2444	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2445	benchmarks actually make blocking connects and use 100% blocking I/O,
		2446	defeating the purpose of an event-based solution. All of the newly
		2447	written AnyEvent benchmarks use 100% non-blocking connects (using
		2448	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2449	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2450	generally require a lot more bookkeeping and event handling than blocking
		2451	connects (which involve a single syscall only).
		2452
		2453	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2454	offers similar expressive power as POE and IO::Lambda, using conventional
		2455	Perl syntax. This means that both the echo server and the client are 100%
		2456	non-blocking, further placing it at a disadvantage.
		2457
		2458	As you can see, the AnyEvent + EV combination even beats the
		2459	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2460	backend easily beats IO::Lambda and POE.
		2461
		2462	And even the 100% non-blocking version written using the high-level (and
		2463	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2464	higher level ("unoptimised") abstractions by a large margin, even though
		2465	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2466
		2467	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2468	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2469	part of the IO::Lambda distribution and were used without any changes.
		2470
1901		2471
1902	=head1 SIGNALS	2472	=head1 SIGNALS
1903		2473
1904	AnyEvent currently installs handlers for these signals:	2474	AnyEvent currently installs handlers for these signals:
1905		2475
…		…
1908	=item SIGCHLD	2478	=item SIGCHLD
1909		2479
1910	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2480	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1911	emulation for event loops that do not support them natively. Also, some	2481	emulation for event loops that do not support them natively. Also, some
1912	event loops install a similar handler.	2482	event loops install a similar handler.
		2483
		2484	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2485	AnyEvent will reset it to default, to avoid losing child exit statuses.
1913		2486
1914	=item SIGPIPE	2487	=item SIGPIPE
1915		2488
1916	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2489	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1917	when AnyEvent gets loaded.	2490	when AnyEvent gets loaded.
…		…
1929		2502
1930	=back	2503	=back
1931		2504
1932	=cut	2505	=cut
1933		2506
		2507	undef $SIG{CHLD}
		2508	if $SIG{CHLD} eq 'IGNORE';
		2509
1934	$SIG{PIPE} = sub { }	2510	$SIG{PIPE} = sub { }
1935	unless defined $SIG{PIPE};	2511	unless defined $SIG{PIPE};
1936		2512
		2513	=head1 RECOMMENDED/OPTIONAL MODULES
		2514
		2515	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2516	its built-in modules) are required to use it.
		2517
		2518	That does not mean that AnyEvent won't take advantage of some additional
		2519	modules if they are installed.
		2520
		2521	This section explains which additional modules will be used, and how they
		2522	affect AnyEvent's operation.
		2523
		2524	=over 4
		2525
		2526	=item L<Async::Interrupt>
		2527
		2528	This slightly arcane module is used to implement fast signal handling: To
		2529	my knowledge, there is no way to do completely race-free and quick
		2530	signal handling in pure perl. To ensure that signals still get
		2531	delivered, AnyEvent will start an interval timer to wake up perl (and
		2532	catch the signals) with some delay (default is 10 seconds, look for
		2533	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2534
		2535	If this module is available, then it will be used to implement signal
		2536	catching, which means that signals will not be delayed, and the event loop
		2537	will not be interrupted regularly, which is more efficient (and good for
		2538	battery life on laptops).
		2539
		2540	This affects not just the pure-perl event loop, but also other event loops
		2541	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2542
		2543	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2544	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2545	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2546	does nothing for those backends.
		2547
		2548	=item L<EV>
		2549
		2550	This module isn't really "optional", as it is simply one of the backend
		2551	event loops that AnyEvent can use. However, it is simply the best event
		2552	loop available in terms of features, speed and stability: It supports
		2553	the AnyEvent API optimally, implements all the watcher types in XS, does
		2554	automatic timer adjustments even when no monotonic clock is available,
		2555	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2556	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2557	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2558
		2559	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2560	then this module will do nothing for you.
		2561
		2562	=item L<Guard>
		2563
		2564	The guard module, when used, will be used to implement
		2565	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2566	lot less memory), but otherwise doesn't affect guard operation much. It is
		2567	purely used for performance.
		2568
		2569	=item L<JSON> and L<JSON::XS>
		2570
		2571	One of these modules is required when you want to read or write JSON data
		2572	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2573	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2574
		2575	=item L<Net::SSLeay>
		2576
		2577	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2578	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2579	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2580
		2581	=item L<Time::HiRes>
		2582
		2583	This module is part of perl since release 5.008. It will be used when the
		2584	chosen event library does not come with a timing source of its own. The
		2585	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2586	try to use a monotonic clock for timing stability.
		2587
		2588	=back
		2589
1937		2590
1938	=head1 FORK	2591	=head1 FORK
1939		2592
1940	Most event libraries are not fork-safe. The ones who are usually are	2593	Most event libraries are not fork-safe. The ones who are usually are
1941	because they rely on inefficient but fork-safe C<select> or C<poll>	2594	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1942	calls. Only L<EV> is fully fork-aware.	2595	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2596	are usually badly thought-out hacks that are incompatible with fork in
		2597	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2598	continue event-processing in both parent and child (or both, if you know
		2599	what you are doing).
		2600
		2601	This means that, in general, you cannot fork and do event processing in
		2602	the child if the event library was initialised before the fork (which
		2603	usually happens when the first AnyEvent watcher is created, or the library
		2604	is loaded).
1943		2605
1944	If you have to fork, you must either do so I<before> creating your first	2606	If you have to fork, you must either do so I<before> creating your first
1945	watcher OR you must not use AnyEvent at all in the child.	2607	watcher OR you must not use AnyEvent at all in the child OR you must do
		2608	something completely out of the scope of AnyEvent.
		2609
		2610	The problem of doing event processing in the parent I<and> the child
		2611	is much more complicated: even for backends that I<are> fork-aware or
		2612	fork-safe, their behaviour is not usually what you want: fork clones all
		2613	watchers, that means all timers, I/O watchers etc. are active in both
		2614	parent and child, which is almost never what you want. USing C<exec>
		2615	to start worker children from some kind of manage rprocess is usually
		2616	preferred, because it is much easier and cleaner, at the expense of having
		2617	to have another binary.
1946		2618
1947		2619
1948	=head1 SECURITY CONSIDERATIONS	2620	=head1 SECURITY CONSIDERATIONS
1949		2621
1950	AnyEvent can be forced to load any event model via	2622	AnyEvent can be forced to load any event model via
…		…
1962	use AnyEvent;	2634	use AnyEvent;
1963		2635
1964	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2636	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1965	be used to probe what backend is used and gain other information (which is	2637	be used to probe what backend is used and gain other information (which is
1966	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2638	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1967	$ENV{PERL_ANYEGENT_STRICT}.	2639	$ENV{PERL_ANYEVENT_STRICT}.
		2640
		2641	Note that AnyEvent will remove I<all> environment variables starting with
		2642	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2643	enabled.
1968		2644
1969		2645
1970	=head1 BUGS	2646	=head1 BUGS
1971		2647
1972	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2648	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
…		…
1984	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2660	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1985		2661
1986	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2662	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1987	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2663	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1988	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2664	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1989	L<AnyEvent::Impl::POE>.	2665	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1990		2666
1991	Non-blocking file handles, sockets, TCP clients and	2667	Non-blocking file handles, sockets, TCP clients and
1992	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2668	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1993		2669
1994	Asynchronous DNS: L<AnyEvent::DNS>.	2670	Asynchronous DNS: L<AnyEvent::DNS>.
1995		2671
1996	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2672	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2673	L<Coro::Event>,
1997		2674
1998	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2675	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2676	L<AnyEvent::HTTP>.
1999		2677
2000		2678
2001	=head1 AUTHOR	2679	=head1 AUTHOR
2002		2680
2003	Marc Lehmann <schmorp@schmorp.de>	2681	Marc Lehmann <schmorp@schmorp.de>

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