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Revision 1.335 by root, Wed Oct 13 01:17:02 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	An FAQ document is available as L<AnyEvent::FAQ>.
		52
		53	There also is a mailinglist for discussing all things AnyEvent, and an IRC
		54	channel, too.
		55
		56	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		57	Repository>, at L<http://anyevent.schmorp.de>, for more info.
44		58
45	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
46		60
47	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	61	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
48	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
…		…
64	module users into the same thing by forcing them to use the same event	78	module users into the same thing by forcing them to use the same event
65	model you use.	79	model you use.
66		80
67	For modules like POE or IO::Async (which is a total misnomer as it is	81	For modules like POE or IO::Async (which is a total misnomer as it is
68	actually doing all I/O I<synchronously>...), using them in your module is	82	actually doing all I/O I<synchronously>...), using them in your module is
69	like joining a cult: After you joined, you are dependent on them and you	83	like joining a cult: After you join, you are dependent on them and you
70	cannot use anything else, as they are simply incompatible to everything	84	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	85	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.	86	module are I<also> forced to use the same event loop you use.
73		87
74	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
75	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	89	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
76	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	90	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
77	your module uses one of those, every user of your module has to use it,	91	your module uses one of those, every user of your module has to use it,
78	too. But if your module uses AnyEvent, it works transparently with all	92	too. But if your module uses AnyEvent, it works transparently with all
79	event models it supports (including stuff like IO::Async, as long as those	93	event models it supports (including stuff like IO::Async, as long as those
80	use one of the supported event loops. It is trivial to add new event loops	94	use one of the supported event loops. It is easy to add new event loops
81	to AnyEvent, too, so it is future-proof).	95	to AnyEvent, too, so it is future-proof).
82		96
83	In addition to being free of having to use I<the one and only true event	97	In addition to being free of having to use I<the one and only true event
84	model>, AnyEvent also is free of bloat and policy: with POE or similar	98	model>, AnyEvent also is free of bloat and policy: with POE or similar
85	modules, you get an enormous amount of code and strict rules you have to	99	modules, you get an enormous amount of code and strict rules you have to
86	follow. AnyEvent, on the other hand, is lean and up to the point, by only	100	follow. AnyEvent, on the other hand, is lean and to the point, by only
87	offering the functionality that is necessary, in as thin as a wrapper as	101	offering the functionality that is necessary, in as thin as a wrapper as
88	technically possible.	102	technically possible.
89		103
90	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
91	of useful functionality, such as an asynchronous DNS resolver, 100%	105	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	111	useful) and you want to force your users to use the one and only event
98	model, you should I<not> use this module.	112	model, you should I<not> use this module.
99		113
100	=head1 DESCRIPTION	114	=head1 DESCRIPTION
101		115
102	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
103	allows module authors to utilise an event loop without forcing module	117	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	118	module users to use a specific event loop implementation (since more
105	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
106		120
107	The interface itself is vaguely similar, but not identical to the L<Event>	121	The interface itself is vaguely similar, but not identical to the L<Event>
108	module.	122	module.
109		123
110	During the first call of any watcher-creation method, the module tries	124	During the first call of any watcher-creation method, the module tries
111	to detect the currently loaded event loop by probing whether one of the	125	to detect the currently loaded event loop by probing whether one of the
112	following modules is already loaded: L<EV>,	126	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>,	127	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	128	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	129	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	130	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	131	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		132
121	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
122	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
123	that model the default. For example:	135	that model the default. For example:
124		136
…		…
126	use AnyEvent;	138	use AnyEvent;
127		139
128	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
129		141
130	The I<likely> means that, if any module loads another event model and	142	The I<likely> means that, if any module loads another event model and
131	starts using it, all bets are off. Maybe you should tell their authors to	143	starts using it, all bets are off - this case should be very rare though,
132	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
133		146
134	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called
135	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	148	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
136	explicitly and enjoy the high availability of that event loop :)	149	explicitly and enjoy the high availability of that event loop :)
137		150
…		…
146	callback when the event occurs (of course, only when the event model	159	callback when the event occurs (of course, only when the event model
147	is in control).	160	is in control).
148		161
149	Note that B<callbacks must not permanently change global variables>	162	Note that B<callbacks must not permanently change global variables>
150	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<	163	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
151	callbacks must not C<die> >>. The former is good programming practise in	164	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	165	Perl and the latter stems from the fact that exception handling differs
153	widely between event loops.	166	widely between event loops.
154		167
155	To disable the watcher you have to destroy it (e.g. by setting the	168	To disable a watcher you have to destroy it (e.g. by setting the
156	variable you store it in to C<undef> or otherwise deleting all references	169	variable you store it in to C<undef> or otherwise deleting all references
157	to it).	170	to it).
158		171
159	All watchers are created by calling a method on the C<AnyEvent> class.	172	All watchers are created by calling a method on the C<AnyEvent> class.
160		173
161	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
162	example), or need to refer to their watcher object in other ways.	175	example), or need to refer to their watcher object in other ways.
163		176
164	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
165		178
166	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
167	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
168	undef $w;	181	undef $w;
169	});	182	});
…		…
172	my variables are only visible after the statement in which they are	185	my variables are only visible after the statement in which they are
173	declared.	186	declared.
174		187
175	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
176		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
177	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	196	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
178	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
179		198
180	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
181	for events (AnyEvent might or might not keep a reference to this file	200	for events (AnyEvent might or might not keep a reference to this file
182	handle). Note that only file handles pointing to things for which	201	handle). Note that only file handles pointing to things for which
183	non-blocking operation makes sense are allowed. This includes sockets,	202	non-blocking operation makes sense are allowed. This includes sockets,
184	most character devices, pipes, fifos and so on, but not for example files	203	most character devices, pipes, fifos and so on, but not for example files
185	or block devices.	204	or block devices.
…		…
195		214
196	The I/O watcher might use the underlying file descriptor or a copy of it.	215	The I/O watcher might use the underlying file descriptor or a copy of it.
197	You must not close a file handle as long as any watcher is active on the	216	You must not close a file handle as long as any watcher is active on the
198	underlying file descriptor.	217	underlying file descriptor.
199		218
200	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
201	always use non-blocking calls when reading/writing from/to your file	220	always use non-blocking calls when reading/writing from/to your file
202	handles.	221	handles.
203		222
204	Example: wait for readability of STDIN, then read a line and disable the	223	Example: wait for readability of STDIN, then read a line and disable the
205	watcher.	224	watcher.
…		…
210	undef $w;	229	undef $w;
211	});	230	});
212		231
213	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
214		233
		234	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		235
		236	$w = AnyEvent->timer (
		237	after => <fractional_seconds>,
		238	interval => <fractional_seconds>,
		239	cb => <callback>,
		240	);
		241
215	You can create a time watcher by calling the C<< AnyEvent->timer >>	242	You can create a time watcher by calling the C<< AnyEvent->timer >>
216	method with the following mandatory arguments:	243	method with the following mandatory arguments:
217		244
218	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
219	supported) the callback should be invoked. C<cb> is the callback to invoke	246	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
221		248
222	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
223	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
224	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
225		252
226	The callback will normally be invoked once only. If you specify another	253	The callback will normally be invoked only once. If you specify another
227	parameter, C<interval>, as a strictly positive number (> 0), then the	254	parameter, C<interval>, as a strictly positive number (> 0), then the
228	callback will be invoked regularly at that interval (in fractional	255	callback will be invoked regularly at that interval (in fractional
229	seconds) after the first invocation. If C<interval> is specified with a	256	seconds) after the first invocation. If C<interval> is specified with a
230	false value, then it is treated as if it were missing.	257	false value, then it is treated as if it were not specified at all.
231		258
232	The callback will be rescheduled before invoking the callback, but no	259	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	260	attempt is made to avoid timer drift in most backends, so the interval is
234	only approximate.	261	only approximate.
235		262
236	Example: fire an event after 7.7 seconds.	263	Example: fire an event after 7.7 seconds.
237		264
238	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
256		283
257	While most event loops expect timers to specified in a relative way, they	284	While most event loops expect timers to specified in a relative way, they
258	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
259	"jumps", for example, when ntp decides to set your clock backwards from	286	"jumps", for example, when ntp decides to set your clock backwards from
260	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to	287	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
261	fire "after" a second might actually take six years to finally fire.	288	fire "after a second" might actually take six years to finally fire.
262		289
263	AnyEvent cannot compensate for this. The only event loop that is conscious	290	AnyEvent cannot compensate for this. The only event loop that is conscious
264	about these issues is L<EV>, which offers both relative (ev_timer, based	291	of these issues is L<EV>, which offers both relative (ev_timer, based
265	on true relative time) and absolute (ev_periodic, based on wallclock time)	292	on true relative time) and absolute (ev_periodic, based on wallclock time)
266	timers.	293	timers.
267		294
268	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
269	AnyEvent API.	296	AnyEvent API.
…		…
291	I<In almost all cases (in all cases if you don't care), this is the	318	I<In almost all cases (in all cases if you don't care), this is the
292	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
293		320
294	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
295	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
296	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
297		324
298	The rest of this section is only of relevance if you try to be very exact	325	The rest of this section is only of relevance if you try to be very exact
299	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
300		327
301	For a practical example of when these times differ, consider L<Event::Lib>	328	For a practical example of when these times differ, consider L<Event::Lib>
302	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
303		330
304	The event loop is running and has just invoked one of your callback at	331	The event loop is running and has just invoked one of your callbacks at
305	time=500 (assume no other callbacks delay processing). In your callback,	332	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	333	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	334	second) and then (at time=501) you create a relative timer that fires
308	after three seconds.	335	after three seconds.
309		336
…		…
340	might affect timers and time-outs.	367	might affect timers and time-outs.
341		368
342	When this is the case, you can call this method, which will update the	369	When this is the case, you can call this method, which will update the
343	event loop's idea of "current time".	370	event loop's idea of "current time".
344		371
		372	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		373	when mod_perl executes the script, then the event loop will have the wrong
		374	idea about the "current time" (being potentially far in the past, when the
		375	script ran the last time). In that case you should arrange a call to C<<
		376	AnyEvent->now_update >> each time the web server process wakes up again
		377	(e.g. at the start of your script, or in a handler).
		378
345	Note that updating the time I<might> cause some events to be handled.	379	Note that updating the time I<might> cause some events to be handled.
346		380
347	=back	381	=back
348		382
349	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
350		386
351	You can watch for signals using a signal watcher, C<signal> is the signal	387	You can watch for signals using a signal watcher, C<signal> is the signal
352	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl	388	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
353	callback to be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
354		390
…		…
360	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
361	that it might take a while until the signal gets handled by the process,	397	that it might take a while until the signal gets handled by the process,
362	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
363		399
364	The main advantage of using these watchers is that you can share a signal	400	The main advantage of using these watchers is that you can share a signal
365	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
366		403
367	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
368	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
369		407
370	Example: exit on SIGINT	408	Example: exit on SIGINT
371		409
372	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
373		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		437	variable can be changed only before the first signal watcher is created,
		438	and should be left alone otherwise. This variable determines how often
		439	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		440	will cause fewer spurious wake-ups, which is better for power and CPU
		441	saving.
		442
		443	All these problems can be avoided by installing the optional
		444	L<Async::Interrupt> module, which works with most event loops. It will not
		445	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		446	(and not with L<POE> currently, as POE does its own workaround with
		447	one-second latency). For those, you just have to suffer the delays.
		448
374	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
375		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
376	You can also watch on a child process exit and catch its exit status.	453	You can also watch for a child process exit and catch its exit status.
377		454
378	The child process is specified by the C<pid> argument (if set to C<0>, it	455	The child process is specified by the C<pid> argument (on some backends,
379	watches for any child process exit). The watcher will triggered only when	456	using C<0> watches for any child process exit, on others this will
380	the child process has finished and an exit status is available, not on	457	croak). The watcher will be triggered only when the child process has
381	any trace events (stopped/continued).	458	finished and an exit status is available, not on any trace events
		459	(stopped/continued).
382		460
383	The callback will be called with the pid and exit status (as returned by	461	The callback will be called with the pid and exit status (as returned by
384	waitpid), so unlike other watcher types, you I<can> rely on child watcher	462	waitpid), so unlike other watcher types, you I<can> rely on child watcher
385	callback arguments.	463	callback arguments.
386		464
…		…
391		469
392	There is a slight catch to child watchers, however: you usually start them	470	There is a slight catch to child watchers, however: you usually start them
393	I<after> the child process was created, and this means the process could	471	I<after> the child process was created, and this means the process could
394	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
395		473
396	Not all event models handle this correctly (POE doesn't), but even for	474	Not all event models handle this correctly (neither POE nor IO::Async do,
		475	see their AnyEvent::Impl manpages for details), but even for event models
397	event models that I<do> handle this correctly, they usually need to be	476	that I<do> handle this correctly, they usually need to be loaded before
398	loaded before the process exits (i.e. before you fork in the first place).	477	the process exits (i.e. before you fork in the first place). AnyEvent's
		478	pure perl event loop handles all cases correctly regardless of when you
		479	start the watcher.
399		480
400	This means you cannot create a child watcher as the very first thing in an	481	This means you cannot create a child watcher as the very first
401	AnyEvent program, you I<have> to create at least one watcher before you	482	thing in an AnyEvent program, you I<have> to create at least one
402	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	483	watcher before you C<fork> the child (alternatively, you can call
		484	C<AnyEvent::detect>).
		485
		486	As most event loops do not support waiting for child events, they will be
		487	emulated by AnyEvent in most cases, in which the latency and race problems
		488	mentioned in the description of signal watchers apply.
403		489
404	Example: fork a process and wait for it	490	Example: fork a process and wait for it
405		491
406	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
407		493
…		…
419	# do something else, then wait for process exit	505	# do something else, then wait for process exit
420	$done->recv;	506	$done->recv;
421		507
422	=head2 IDLE WATCHERS	508	=head2 IDLE WATCHERS
423		509
424	Sometimes there is a need to do something, but it is not so important	510	$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		511
429	Idle watchers ideally get invoked when the event loop has nothing	512	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	513	until either the watcher is destroyed or new events have been detected.
431	events. Instead of blocking, the idle watcher is invoked.
432		514
433	Most event loops unfortunately do not really support idle watchers (only	515	Idle watchers are useful when there is a need to do something, but it
		516	is not so important (or wise) to do it instantly. The callback will be
		517	invoked only when there is "nothing better to do", which is usually
		518	defined as "all outstanding events have been handled and no new events
		519	have been detected". That means that idle watchers ideally get invoked
		520	when the event loop has just polled for new events but none have been
		521	detected. Instead of blocking to wait for more events, the idle watchers
		522	will be invoked.
		523
		524	Unfortunately, most event loops do not really support idle watchers (only
434	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent	525	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
435	will simply call the callback "from time to time".	526	will simply call the callback "from time to time".
436		527
437	Example: read lines from STDIN, but only process them when the	528	Example: read lines from STDIN, but only process them when the
438	program is otherwise idle:	529	program is otherwise idle:
…		…
454	});	545	});
455	});	546	});
456		547
457	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
458		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
		554
459	If you are familiar with some event loops you will know that all of them	555	If you are familiar with some event loops you will know that all of them
460	require you to run some blocking "loop", "run" or similar function that	556	require you to run some blocking "loop", "run" or similar function that
461	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
462		558
463	AnyEvent is different, it expects somebody else to run the event loop and	559	AnyEvent is slightly different: it expects somebody else to run the event
464	will only block when necessary (usually when told by the user).	560	loop and will only block when necessary (usually when told by the user).
465		561
466	The instrument to do that is called a "condition variable", so called	562	The tool to do that is called a "condition variable", so called because
467	because they represent a condition that must become true.	563	they represent a condition that must become true.
		564
		565	Now is probably a good time to look at the examples further below.
468		566
469	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
470	>> method, usually without arguments. The only argument pair allowed is	568	>> 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	569	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	570	becomes true, with the condition variable as the first argument (but not
474	the results).	571	the results).
475		572
476	After creation, the condition variable is "false" until it becomes "true"	573	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	574	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<<	575	were a callback, read about the caveats in the description for the C<<
479	->send >> method).	576	->send >> method).
480		577
481	Condition variables are similar to callbacks, except that you can	578	Since condition variables are the most complex part of the AnyEvent API, here are
482	optionally wait for them. They can also be called merge points - points	579	some different mental models of what they are - pick the ones you can connect to:
483	in time where multiple outstanding events have been processed. And yet	580
484	another way to call them is transactions - each condition variable can be	581	=over 4
485	used to represent a transaction, which finishes at some point and delivers	582
486	a result.	583	=item * Condition variables are like callbacks - you can call them (and pass them instead
		584	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		585
		586	=item * Condition variables are signals - one side can emit or send them,
		587	the other side can wait for them, or install a handler that is called when
		588	the signal fires.
		589
		590	=item * Condition variables are like "Merge Points" - points in your program
		591	where you merge multiple independent results/control flows into one.
		592
		593	=item * Condition variables represent a transaction - functions that start
		594	some kind of transaction can return them, leaving the caller the choice
		595	between waiting in a blocking fashion, or setting a callback.
		596
		597	=item * Condition variables represent future values, or promises to deliver
		598	some result, long before the result is available.
		599
		600	=back
487		601
488	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
489	for example, if you write a module that does asynchronous http requests,	603	for example, if you write a module that does asynchronous http requests,
490	then a condition variable would be the ideal candidate to signal the	604	then a condition variable would be the ideal candidate to signal the
491	availability of results. The user can either act when the callback is	605	availability of results. The user can either act when the callback is
…		…
504		618
505	Condition variables are represented by hash refs in perl, and the keys	619	Condition variables are represented by hash refs in perl, and the keys
506	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	620	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
507	easy (it is often useful to build your own transaction class on top of	621	easy (it is often useful to build your own transaction class on top of
508	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	622	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
509	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
510		624
511	There are two "sides" to a condition variable - the "producer side" which	625	There are two "sides" to a condition variable - the "producer side" which
512	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
513	for the send to occur.	627	for the send to occur.
514		628
515	Example: wait for a timer.	629	Example: wait for a timer.
516		630
517	# wait till the result is ready	631	# condition: "wait till the timer is fired"
518	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
519		633
520	# do something such as adding a timer	634	# create the timer - we could wait for, say
521	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
522	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
523	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
524	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
525	after => 1,	639	after => 1,
526	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
527	);	641	);
528		642
529	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
530	# calls send	644	# calls ->send
531	$result_ready->recv;	645	$timer_fired->recv;
532		646
533	Example: wait for a timer, but take advantage of the fact that	647	Example: wait for a timer, but take advantage of the fact that condition
534	condition variables are also code references.	648	variables are also callable directly.
535		649
536	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
537	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
538	$done->recv;	652	$done->recv;
539		653
…		…
545		659
546	...	660	...
547		661
548	my @info = $couchdb->info->recv;	662	my @info = $couchdb->info->recv;
549		663
550	And this is how you would just ste a callback to be called whenever the	664	And this is how you would just set a callback to be called whenever the
551	results are available:	665	results are available:
552		666
553	$couchdb->info->cb (sub {	667	$couchdb->info->cb (sub {
554	my @info = $_[0]->recv;	668	my @info = $_[0]->recv;
555	});	669	});
…		…
573	immediately from within send.	687	immediately from within send.
574		688
575	Any arguments passed to the C<send> call will be returned by all	689	Any arguments passed to the C<send> call will be returned by all
576	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
577		691
578	Condition variables are overloaded so one can call them directly	692	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	693	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	694	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		695
587	=item $cv->croak ($error)	696	=item $cv->croak ($error)
588		697
589	Similar to send, but causes all call's to C<< ->recv >> to invoke	698	Similar to send, but causes all calls to C<< ->recv >> to invoke
590	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
591		700
592	This can be used to signal any errors to the condition variable	701	This can be used to signal any errors to the condition variable
593	user/consumer.	702	user/consumer. Doing it this way instead of calling C<croak> directly
		703	delays the error detection, but has the overwhelming advantage that it
		704	diagnoses the error at the place where the result is expected, and not
		705	deep in some event callback with no connection to the actual code causing
		706	the problem.
594		707
595	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
596		709
597	=item $cv->end	710	=item $cv->end
598
599	These two methods are EXPERIMENTAL and MIGHT CHANGE.
600		711
601	These two methods can be used to combine many transactions/events into	712	These two methods can be used to combine many transactions/events into
602	one. For example, a function that pings many hosts in parallel might want	713	one. For example, a function that pings many hosts in parallel might want
603	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
604		715
605	Every call to C<< ->begin >> will increment a counter, and every call to	716	Every call to C<< ->begin >> will increment a counter, and every call to
606	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	717	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
607	>>, the (last) callback passed to C<begin> will be executed. That callback	718	>>, the (last) callback passed to C<begin> will be executed, passing the
608	is I<supposed> to call C<< ->send >>, but that is not required. If no	719	condvar as first argument. That callback is I<supposed> to call C<< ->send
609	callback was set, C<send> will be called without any arguments.	720	>>, but that is not required. If no group callback was set, C<send> will
		721	be called without any arguments.
610		722
611	Let's clarify this with the ping example:	723	You can think of C<< $cv->send >> giving you an OR condition (one call
		724	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		725	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		726
		727	Let's start with a simple example: you have two I/O watchers (for example,
		728	STDOUT and STDERR for a program), and you want to wait for both streams to
		729	close before activating a condvar:
612		730
613	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
614		732
		733	$cv->begin; # first watcher
		734	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		735	defined sysread $fh1, my $buf, 4096
		736	or $cv->end;
		737	});
		738
		739	$cv->begin; # second watcher
		740	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		741	defined sysread $fh2, my $buf, 4096
		742	or $cv->end;
		743	});
		744
		745	$cv->recv;
		746
		747	This works because for every event source (EOF on file handle), there is
		748	one call to C<begin>, so the condvar waits for all calls to C<end> before
		749	sending.
		750
		751	The ping example mentioned above is slightly more complicated, as the
		752	there are results to be passwd back, and the number of tasks that are
		753	begun can potentially be zero:
		754
		755	my $cv = AnyEvent->condvar;
		756
615	my %result;	757	my %result;
616	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
617		759
618	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
619	$cv->begin;	761	$cv->begin;
620	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
621	$result{$host} = ...;	763	$result{$host} = ...;
…		…
636	loop, which serves two important purposes: first, it sets the callback	778	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	779	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	780	C<send> is called even when C<no> hosts are being pinged (the loop
639	doesn't execute once).	781	doesn't execute once).
640		782
641	This is the general pattern when you "fan out" into multiple subrequests:	783	This is the general pattern when you "fan out" into multiple (but
642	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	784	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
643	is called at least once, and then, for each subrequest you start, call	785	the callback and ensure C<end> is called at least once, and then, for each
644	C<begin> and for each subrequest you finish, call C<end>.	786	subrequest you start, call C<begin> and for each subrequest you finish,
		787	call C<end>.
645		788
646	=back	789	=back
647		790
648	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
649		792
…		…
653	=over 4	796	=over 4
654		797
655	=item $cv->recv	798	=item $cv->recv
656		799
657	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
658	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
659	normally.	802	normally.
660		803
661	You can only wait once on a condition - additional calls are valid but	804	You can only wait once on a condition - additional calls are valid but
662	will return immediately.	805	will return immediately.
663		806
…		…
665	function will call C<croak>.	808	function will call C<croak>.
666		809
667	In list context, all parameters passed to C<send> will be returned,	810	In list context, all parameters passed to C<send> will be returned,
668	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
669		812
		813	Note that doing a blocking wait in a callback is not supported by any
		814	event loop, that is, recursive invocation of a blocking C<< ->recv
		815	>> is not allowed, and the C<recv> call will C<croak> if such a
		816	condition is detected. This condition can be slightly loosened by using
		817	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		818	any thread that doesn't run the event loop itself.
		819
670	Not all event models support a blocking wait - some die in that case	820	Not all event models support a blocking wait - some die in that case
671	(programs might want to do that to stay interactive), so I<if you are	821	(programs might want to do that to stay interactive), so I<if you are
672	using this from a module, never require a blocking wait>, but let the	822	using this from a module, never require a blocking wait>. Instead, let the
673	caller decide whether the call will block or not (for example, by coupling	823	caller decide whether the call will block or not (for example, by coupling
674	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
675	callbacks so the caller knows that getting the result will not block,	825	callbacks so the caller knows that getting the result will not block,
676	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
677		827
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	828	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	829	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	830	time). This will work even when the event loop does not support blocking
692	waits otherwise.	831	waits otherwise.
693		832
694	=item $bool = $cv->ready	833	=item $bool = $cv->ready
…		…
700		839
701	This is a mutator function that returns the callback set and optionally	840	This is a mutator function that returns the callback set and optionally
702	replaces it before doing so.	841	replaces it before doing so.
703		842
704	The callback will be called when the condition becomes "true", i.e. when	843	The callback will be called when the condition becomes "true", i.e. when
705	C<send> or C<croak> are called, with the only argument being the condition	844	C<send> or C<croak> are called, with the only argument being the
706	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
707	is guaranteed not to block.	846	callback is called immediately when it is set. Calling C<recv> inside
		847	the callback or at any later time is guaranteed not to block.
708		848
709	=back	849	=back
710		850
		851	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		852
		853	The available backend classes are (every class has its own manpage):
		854
		855	=over 4
		856
		857	=item Backends that are autoprobed when no other event loop can be found.
		858
		859	EV is the preferred backend when no other event loop seems to be in
		860	use. If EV is not installed, then AnyEvent will fall back to its own
		861	pure-perl implementation, which is available everywhere as it comes with
		862	AnyEvent itself.
		863
		864	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		865	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		866
		867	=item Backends that are transparently being picked up when they are used.
		868
		869	These will be used if they are already loaded when the first watcher
		870	is created, in which case it is assumed that the application is using
		871	them. This means that AnyEvent will automatically pick the right backend
		872	when the main program loads an event module before anything starts to
		873	create watchers. Nothing special needs to be done by the main program.
		874
		875	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		876	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		877	AnyEvent::Impl::Tk based on Tk, very broken.
		878	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		879	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		880	AnyEvent::Impl::Irssi used when running within irssi.
		881
		882	=item Backends with special needs.
		883
		884	Qt requires the Qt::Application to be instantiated first, but will
		885	otherwise be picked up automatically. As long as the main program
		886	instantiates the application before any AnyEvent watchers are created,
		887	everything should just work.
		888
		889	AnyEvent::Impl::Qt based on Qt.
		890
		891	Support for IO::Async can only be partial, as it is too broken and
		892	architecturally limited to even support the AnyEvent API. It also
		893	is the only event loop that needs the loop to be set explicitly, so
		894	it can only be used by a main program knowing about AnyEvent. See
		895	L<AnyEvent::Impl::IOAsync> for the gory details.
		896
		897	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		898
		899	=item Event loops that are indirectly supported via other backends.
		900
		901	Some event loops can be supported via other modules:
		902
		903	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		904
		905	B<WxWidgets> has no support for watching file handles. However, you can
		906	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		907	polls 20 times per second, which was considered to be too horrible to even
		908	consider for AnyEvent.
		909
		910	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		911	backend, so it can be supported through POE.
		912
		913	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		914	load L<POE> when detecting them, in the hope that POE will pick them up,
		915	in which case everything will be automatic.
		916
		917	=back
		918
711	=head1 GLOBAL VARIABLES AND FUNCTIONS	919	=head1 GLOBAL VARIABLES AND FUNCTIONS
712		920
		921	These are not normally required to use AnyEvent, but can be useful to
		922	write AnyEvent extension modules.
		923
713	=over 4	924	=over 4
714		925
715	=item $AnyEvent::MODEL	926	=item $AnyEvent::MODEL
716		927
717	Contains C<undef> until the first watcher is being created. Then it	928	Contains C<undef> until the first watcher is being created, before the
		929	backend has been autodetected.
		930
718	contains the event model that is being used, which is the name of the	931	Afterwards it contains the event model that is being used, which is the
719	Perl class implementing the model. This class is usually one of the	932	name of the Perl class implementing the model. This class is usually one
720	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	933	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
721	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	934	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
722		935	will be C<urxvt::anyevent>).
723	The known classes so far are:
724
725	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
726	AnyEvent::Impl::Event based on Event, second best choice.
727	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
728	AnyEvent::Impl::Glib based on Glib, third-best choice.
729	AnyEvent::Impl::Tk based on Tk, very bad choice.
730	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
731	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
732	AnyEvent::Impl::POE based on POE, not generic enough for full support.
733
734	There is no support for WxWidgets, as WxWidgets has no support for
735	watching file handles. However, you can use WxWidgets through the
736	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
737	second, which was considered to be too horrible to even consider for
738	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
739	it's adaptor.
740
741	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
742	autodetecting them.
743		936
744	=item AnyEvent::detect	937	=item AnyEvent::detect
745		938
746	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	939	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
747	if necessary. You should only call this function right before you would	940	if necessary. You should only call this function right before you would
748	have created an AnyEvent watcher anyway, that is, as late as possible at	941	have created an AnyEvent watcher anyway, that is, as late as possible at
749	runtime.	942	runtime, and not e.g. during initialisation of your module.
		943
		944	If you need to do some initialisation before AnyEvent watchers are
		945	created, use C<post_detect>.
750		946
751	=item $guard = AnyEvent::post_detect { BLOCK }	947	=item $guard = AnyEvent::post_detect { BLOCK }
752		948
753	Arranges for the code block to be executed as soon as the event model is	949	Arranges for the code block to be executed as soon as the event model is
754	autodetected (or immediately if this has already happened).	950	autodetected (or immediately if that has already happened).
		951
		952	The block will be executed I<after> the actual backend has been detected
		953	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		954	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		955	other initialisations - see the sources of L<AnyEvent::Strict> or
		956	L<AnyEvent::AIO> to see how this is used.
		957
		958	The most common usage is to create some global watchers, without forcing
		959	event module detection too early, for example, L<AnyEvent::AIO> creates
		960	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		961	avoid autodetecting the event module at load time.
755		962
756	If called in scalar or list context, then it creates and returns an object	963	If called in scalar or list context, then it creates and returns an object
757	that automatically removes the callback again when it is destroyed. See	964	that automatically removes the callback again when it is destroyed (or
		965	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
758	L<Coro::BDB> for a case where this is useful.	966	a case where this is useful.
		967
		968	Example: Create a watcher for the IO::AIO module and store it in
		969	C<$WATCHER>, but do so only do so after the event loop is initialised.
		970
		971	our WATCHER;
		972
		973	my $guard = AnyEvent::post_detect {
		974	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		975	};
		976
		977	# the ||= is important in case post_detect immediately runs the block,
		978	# as to not clobber the newly-created watcher. assigning both watcher and
		979	# post_detect guard to the same variable has the advantage of users being
		980	# able to just C<undef $WATCHER> if the watcher causes them grief.
		981
		982	$WATCHER ||= $guard;
759		983
760	=item @AnyEvent::post_detect	984	=item @AnyEvent::post_detect
761		985
762	If there are any code references in this array (you can C<push> to it	986	If there are any code references in this array (you can C<push> to it
763	before or after loading AnyEvent), then they will called directly after	987	before or after loading AnyEvent), then they will be called directly
764	the event loop has been chosen.	988	after the event loop has been chosen.
765		989
766	You should check C<$AnyEvent::MODEL> before adding to this array, though:	990	You should check C<$AnyEvent::MODEL> before adding to this array, though:
767	if it contains a true value then the event loop has already been detected,	991	if it is defined then the event loop has already been detected, and the
768	and the array will be ignored.	992	array will be ignored.
769		993
770	Best use C<AnyEvent::post_detect { BLOCK }> instead.	994	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		995	it, as it takes care of these details.
		996
		997	This variable is mainly useful for modules that can do something useful
		998	when AnyEvent is used and thus want to know when it is initialised, but do
		999	not need to even load it by default. This array provides the means to hook
		1000	into AnyEvent passively, without loading it.
		1001
		1002	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1003	together, you could put this into Coro (this is the actual code used by
		1004	Coro to accomplish this):
		1005
		1006	if (defined $AnyEvent::MODEL) {
		1007	# AnyEvent already initialised, so load Coro::AnyEvent
		1008	require Coro::AnyEvent;
		1009	} else {
		1010	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1011	# as soon as it is
		1012	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1013	}
771		1014
772	=back	1015	=back
773		1016
774	=head1 WHAT TO DO IN A MODULE	1017	=head1 WHAT TO DO IN A MODULE
775		1018
…		…
786	because it will stall the whole program, and the whole point of using	1029	because it will stall the whole program, and the whole point of using
787	events is to stay interactive.	1030	events is to stay interactive.
788		1031
789	It is fine, however, to call C<< ->recv >> when the user of your module	1032	It is fine, however, to call C<< ->recv >> when the user of your module
790	requests it (i.e. if you create a http request object ad have a method	1033	requests it (i.e. if you create a http request object ad have a method
791	called C<results> that returns the results, it should call C<< ->recv >>	1034	called C<results> that returns the results, it may call C<< ->recv >>
792	freely, as the user of your module knows what she is doing. always).	1035	freely, as the user of your module knows what she is doing. Always).
793		1036
794	=head1 WHAT TO DO IN THE MAIN PROGRAM	1037	=head1 WHAT TO DO IN THE MAIN PROGRAM
795		1038
796	There will always be a single main program - the only place that should	1039	There will always be a single main program - the only place that should
797	dictate which event model to use.	1040	dictate which event model to use.
798		1041
799	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1042	If the program is not event-based, it need not do anything special, even
800	do anything special (it does not need to be event-based) and let AnyEvent	1043	when it depends on a module that uses an AnyEvent. If the program itself
801	decide which implementation to chose if some module relies on it.	1044	uses AnyEvent, but does not care which event loop is used, all it needs
		1045	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1046	available loop implementation.
802		1047
803	If the main program relies on a specific event model - for example, in	1048	If the main program relies on a specific event model - for example, in
804	Gtk2 programs you have to rely on the Glib module - you should load the	1049	Gtk2 programs you have to rely on the Glib module - you should load the
805	event module before loading AnyEvent or any module that uses it: generally	1050	event module before loading AnyEvent or any module that uses it: generally
806	speaking, you should load it as early as possible. The reason is that	1051	speaking, you should load it as early as possible. The reason is that
807	modules might create watchers when they are loaded, and AnyEvent will	1052	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	1053	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.	1054	might choose the wrong one unless you load the correct one yourself.
810		1055
811	You can chose to use a pure-perl implementation by loading the	1056	You can chose to use a pure-perl implementation by loading the
812	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1057	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
813	everywhere, but letting AnyEvent chose the model is generally better.	1058	everywhere, but letting AnyEvent chose the model is generally better.
814		1059
…		…
830		1075
831		1076
832	=head1 OTHER MODULES	1077	=head1 OTHER MODULES
833		1078
834	The following is a non-exhaustive list of additional modules that use	1079	The following is a non-exhaustive list of additional modules that use
835	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1080	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
836	in the same program. Some of the modules come with AnyEvent, some are	1081	modules and other event loops in the same program. Some of the modules
837	available via CPAN.	1082	come as part of AnyEvent, the others are available via CPAN.
838		1083
839	=over 4	1084	=over 4
840		1085
841	=item L<AnyEvent::Util>	1086	=item L<AnyEvent::Util>
842		1087
843	Contains various utility functions that replace often-used but blocking	1088	Contains various utility functions that replace often-used blocking
844	functions such as C<inet_aton> by event-/callback-based versions.	1089	functions such as C<inet_aton> with event/callback-based versions.
845		1090
846	=item L<AnyEvent::Socket>	1091	=item L<AnyEvent::Socket>
847		1092
848	Provides various utility functions for (internet protocol) sockets,	1093	Provides various utility functions for (internet protocol) sockets,
849	addresses and name resolution. Also functions to create non-blocking tcp	1094	addresses and name resolution. Also functions to create non-blocking tcp
…		…
851		1096
852	=item L<AnyEvent::Handle>	1097	=item L<AnyEvent::Handle>
853		1098
854	Provide read and write buffers, manages watchers for reads and writes,	1099	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	1100	supports raw and formatted I/O, I/O queued and fully transparent and
856	non-blocking SSL/TLS.	1101	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
857		1102
858	=item L<AnyEvent::DNS>	1103	=item L<AnyEvent::DNS>
859		1104
860	Provides rich asynchronous DNS resolver capabilities.	1105	Provides rich asynchronous DNS resolver capabilities.
861		1106
		1107	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1108
		1109	Implement event-based interfaces to the protocols of the same name (for
		1110	the curious, IGS is the International Go Server and FCP is the Freenet
		1111	Client Protocol).
		1112
		1113	=item L<AnyEvent::Handle::UDP>
		1114
		1115	Here be danger!
		1116
		1117	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1118	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1119	its use of a stream-based API with a protocol that isn't streamable, that
		1120	the only way to improve it is to delete it.
		1121
		1122	It features data corruption (but typically only under load) and general
		1123	confusion. On top, the author is not only clueless about UDP but also
		1124	fact-resistant - some gems of his understanding: "connect doesn't work
		1125	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1126	packets", "I don't need to implement proper error checking as UDP doesn't
		1127	support error checking" and so on - he doesn't even understand what's
		1128	wrong with his module when it is explained to him.
		1129
862	=item L<AnyEvent::HTTP>	1130	=item L<AnyEvent::DBI>
863		1131
864	A simple-to-use HTTP library that is capable of making a lot of concurrent	1132	Executes L<DBI> requests asynchronously in a proxy process for you,
865	HTTP requests.	1133	notifying you in an event-based way when the operation is finished.
		1134
		1135	=item L<AnyEvent::AIO>
		1136
		1137	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1138	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1139	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1140	file I/O, and much more.
866		1141
867	=item L<AnyEvent::HTTPD>	1142	=item L<AnyEvent::HTTPD>
868		1143
869	Provides a simple web application server framework.	1144	A simple embedded webserver.
870		1145
871	=item L<AnyEvent::FastPing>	1146	=item L<AnyEvent::FastPing>
872		1147
873	The fastest ping in the west.	1148	The fastest ping in the west.
874		1149
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>	1150	=item L<Coro>
917		1151
918	Has special support for AnyEvent via L<Coro::AnyEvent>.	1152	Has special support for AnyEvent via L<Coro::AnyEvent>.
919		1153
920	=item L<IO::Lambda>
921
922	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
923
924	=back	1154	=back
925		1155
926	=cut	1156	=cut
927		1157
928	package AnyEvent;	1158	package AnyEvent;
929		1159
930	no warnings;	1160	# basically a tuned-down version of common::sense
931	use strict qw(vars subs);	1161	sub common_sense {
		1162	# from common:.sense 3.3
		1163	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf3\x0f\xc0\xf0\xfc\x33\x00";
		1164	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1165	$^H |= 0x00000600;
		1166	}
932		1167
		1168	BEGIN { AnyEvent::common_sense }
		1169
933	use Carp;	1170	use Carp ();
934		1171
935	our $VERSION = 4.352;	1172	our $VERSION = '5.271';
936	our $MODEL;	1173	our $MODEL;
937		1174
938	our $AUTOLOAD;	1175	our $AUTOLOAD;
939	our @ISA;	1176	our @ISA;
940		1177
941	our @REGISTRY;	1178	our @REGISTRY;
942		1179
943	our $WIN32;	1180	our $VERBOSE;
944		1181
945	BEGIN {	1182	BEGIN {
946	my $win32 = ! ! ($^O =~ /mswin32/i);	1183	require "AnyEvent/constants.pl";
947	eval "sub WIN32(){ $win32 }";
948	}
949		1184
		1185	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1186
		1187	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1188	if ${^TAINT};
		1189
950	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1190	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1191
		1192	}
		1193
		1194	our $MAX_SIGNAL_LATENCY = 10;
951		1195
952	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1196	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
953		1197
954	{	1198	{
955	my $idx;	1199	my $idx;
…		…
957	for reverse split /\s*,\s*/,	1201	for reverse split /\s*,\s*/,
958	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1202	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
959	}	1203	}
960		1204
961	my @models = (	1205	my @models = (
962	[EV:: => AnyEvent::Impl::EV::],	1206	[EV:: => AnyEvent::Impl::EV:: , 1],
963	[Event:: => AnyEvent::Impl::Event::],
964	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1207	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
965	# everything below here will not be autoprobed	1208	# everything below here will not (normally) be autoprobed
966	# as the pureperl backend should work everywhere	1209	# as the pureperl backend should work everywhere
967	# and is usually faster	1210	# and is usually faster
		1211	[Event:: => AnyEvent::Impl::Event::, 1],
		1212	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1213	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1214	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
968	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1215	[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	1216	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
972	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1217	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
973	[Wx:: => AnyEvent::Impl::POE::],	1218	[Wx:: => AnyEvent::Impl::POE::],
974	[Prima:: => AnyEvent::Impl::POE::],	1219	[Prima:: => AnyEvent::Impl::POE::],
		1220	# IO::Async is just too broken - we would need workarounds for its
		1221	# byzantine signal and broken child handling, among others.
		1222	# IO::Async is rather hard to detect, as it doesn't have any
		1223	# obvious default class.
		1224	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1225	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1226	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1227	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
975	);	1228	);
976		1229
977	our %method = map +($_ => 1),	1230	our %method = map +($_ => 1),
978	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1231	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
979		1232
980	our @post_detect;	1233	our @post_detect;
981		1234
982	sub post_detect(&) {	1235	sub post_detect(&) {
983	my ($cb) = @_;	1236	my ($cb) = @_;
984		1237
985	if ($MODEL) {
986	$cb->();
987
988	1
989	} else {
990	push @post_detect, $cb;	1238	push @post_detect, $cb;
991		1239
992	defined wantarray	1240	defined wantarray
993	? bless \$cb, "AnyEvent::Util::postdetect"	1241	? bless \$cb, "AnyEvent::Util::postdetect"
994	: ()	1242	: ()
995	}
996	}	1243	}
997		1244
998	sub AnyEvent::Util::postdetect::DESTROY {	1245	sub AnyEvent::Util::postdetect::DESTROY {
999	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1246	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1000	}	1247	}
1001		1248
1002	sub detect() {	1249	sub detect() {
		1250	# free some memory
		1251	*detect = sub () { $MODEL };
		1252
		1253	local $!; # for good measure
		1254	local $SIG{__DIE__};
		1255
		1256	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1257	my $model = "AnyEvent::Impl::$1";
		1258	if (eval "require $model") {
		1259	$MODEL = $model;
		1260	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
		1261	} else {
		1262	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
		1263	}
		1264	}
		1265
		1266	# check for already loaded models
1003	unless ($MODEL) {	1267	unless ($MODEL) {
1004	no strict 'refs';	1268	for (@REGISTRY, @models) {
1005	local $SIG{__DIE__};	1269	my ($package, $model) = @$_;
1006		1270	if (${"$package\::VERSION"} > 0) {
1007	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1008	my $model = "AnyEvent::Impl::$1";
1009	if (eval "require $model") {	1271	if (eval "require $model") {
1010	$MODEL = $model;	1272	$MODEL = $model;
1011	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1273	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1012	} else {	1274	last;
1013	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1275	}
1014	}	1276	}
1015	}	1277	}
1016		1278
1017	# check for already loaded models
1018	unless ($MODEL) {	1279	unless ($MODEL) {
		1280	# try to autoload a model
1019	for (@REGISTRY, @models) {	1281	for (@REGISTRY, @models) {
1020	my ($package, $model) = @$_;	1282	my ($package, $model, $autoload) = @$_;
		1283	if (
		1284	$autoload
		1285	and eval "require $package"
1021	if (${"$package\::VERSION"} > 0) {	1286	and ${"$package\::VERSION"} > 0
1022	if (eval "require $model") {	1287	and eval "require $model"
		1288	) {
1023	$MODEL = $model;	1289	$MODEL = $model;
1024	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1290	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1025	last;	1291	last;
1026	}
1027	}	1292	}
1028	}	1293	}
1029		1294
1030	unless ($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	1295	$MODEL
1045	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";	1296	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
1046	}
1047	}	1297	}
1048
1049	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1050
1051	unshift @ISA, $MODEL;
1052
1053	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1054
1055	(shift @post_detect)->() while @post_detect;
1056	}	1298	}
		1299
		1300	@models = (); # free probe data
		1301
		1302	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1303	unshift @ISA, $MODEL;
		1304
		1305	# now nuke some methods that are overriden by the backend.
		1306	# SUPER is not allowed.
		1307	for (qw(time signal child idle)) {
		1308	undef &{"AnyEvent::Base::$_"}
		1309	if defined &{"$MODEL\::$_"};
		1310	}
		1311
		1312	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1313
		1314	(shift @post_detect)->() while @post_detect;
		1315
		1316	*post_detect = sub(&) {
		1317	shift->();
		1318
		1319	undef
		1320	};
1057		1321
1058	$MODEL	1322	$MODEL
1059	}	1323	}
1060		1324
1061	sub AUTOLOAD {	1325	sub AUTOLOAD {
1062	(my $func = $AUTOLOAD) =~ s/.*://;	1326	(my $func = $AUTOLOAD) =~ s/.*://;
1063		1327
1064	$method{$func}	1328	$method{$func}
1065	or croak "$func: not a valid method for AnyEvent objects";	1329	or Carp::croak "$func: not a valid AnyEvent class method";
1066		1330
1067	detect unless $MODEL;	1331	detect;
1068		1332
1069	my $class = shift;	1333	my $class = shift;
1070	$class->$func (@_);	1334	$class->$func (@_);
1071	}	1335	}
1072		1336
1073	# utility function to dup a filehandle. this is used by many backends	1337	# utility function to dup a filehandle. this is used by many backends
1074	# to support binding more than one watcher per filehandle (they usually	1338	# 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).	1339	# allow only one watcher per fd, so we dup it to get a different one).
1076	sub _dupfh($$$$) {	1340	sub _dupfh($$;$$) {
1077	my ($poll, $fh, $r, $w) = @_;	1341	my ($poll, $fh, $r, $w) = @_;
1078		1342
1079	# cygwin requires the fh mode to be matching, unix doesn't	1343	# cygwin requires the fh mode to be matching, unix doesn't
1080	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1344	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1081	: $poll eq "w" ? ($w, ">")
1082	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1083		1345
1084	open my $fh2, "$mode&" . fileno $fh	1346	open my $fh2, $mode, $fh
1085	or die "cannot dup() filehandle: $!,";	1347	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1086		1348
1087	# we assume CLOEXEC is already set by perl in all important cases	1349	# we assume CLOEXEC is already set by perl in all important cases
1088		1350
1089	($fh2, $rw)	1351	($fh2, $rw)
1090	}	1352	}
1091		1353
		1354	=head1 SIMPLIFIED AE API
		1355
		1356	Starting with version 5.0, AnyEvent officially supports a second, much
		1357	simpler, API that is designed to reduce the calling, typing and memory
		1358	overhead by using function call syntax and a fixed number of parameters.
		1359
		1360	See the L<AE> manpage for details.
		1361
		1362	=cut
		1363
		1364	package AE;
		1365
		1366	our $VERSION = $AnyEvent::VERSION;
		1367
		1368	# fall back to the main API by default - backends and AnyEvent::Base
		1369	# implementations can overwrite these.
		1370
		1371	sub io($$$) {
		1372	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1373	}
		1374
		1375	sub timer($$$) {
		1376	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1377	}
		1378
		1379	sub signal($$) {
		1380	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1381	}
		1382
		1383	sub child($$) {
		1384	AnyEvent->child (pid => $_[0], cb => $_[1])
		1385	}
		1386
		1387	sub idle($) {
		1388	AnyEvent->idle (cb => $_[0])
		1389	}
		1390
		1391	sub cv(;&) {
		1392	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1393	}
		1394
		1395	sub now() {
		1396	AnyEvent->now
		1397	}
		1398
		1399	sub now_update() {
		1400	AnyEvent->now_update
		1401	}
		1402
		1403	sub time() {
		1404	AnyEvent->time
		1405	}
		1406
1092	package AnyEvent::Base;	1407	package AnyEvent::Base;
1093		1408
1094	# default implementations for many methods	1409	# default implementations for many methods
1095		1410
1096	BEGIN {	1411	sub time {
		1412	eval q{ # poor man's autoloading {}
		1413	# probe for availability of Time::HiRes
1097	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1414	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1415	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1098	*_time = \&Time::HiRes::time;	1416	*AE::time = \&Time::HiRes::time;
1099	# if (eval "use POSIX (); (POSIX::times())...	1417	# if (eval "use POSIX (); (POSIX::times())...
1100	} else {	1418	} else {
		1419	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1101	*_time = sub { time }; # epic fail	1420	*AE::time = sub (){ time }; # epic fail
		1421	}
		1422
		1423	*time = sub { AE::time }; # different prototypes
		1424	};
		1425	die if $@;
		1426
		1427	&time
		1428	}
		1429
		1430	*now = \&time;
		1431
		1432	sub now_update { }
		1433
		1434	# default implementation for ->condvar
		1435
		1436	sub condvar {
		1437	eval q{ # poor man's autoloading {}
		1438	*condvar = sub {
		1439	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1440	};
		1441
		1442	*AE::cv = sub (;&) {
		1443	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1444	};
		1445	};
		1446	die if $@;
		1447
		1448	&condvar
		1449	}
		1450
		1451	# default implementation for ->signal
		1452
		1453	our $HAVE_ASYNC_INTERRUPT;
		1454
		1455	sub _have_async_interrupt() {
		1456	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1457	&& eval "use Async::Interrupt 1.02 (); 1")
		1458	unless defined $HAVE_ASYNC_INTERRUPT;
		1459
		1460	$HAVE_ASYNC_INTERRUPT
		1461	}
		1462
		1463	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1464	our (%SIG_ASY, %SIG_ASY_W);
		1465	our ($SIG_COUNT, $SIG_TW);
		1466
		1467	# install a dummy wakeup watcher to reduce signal catching latency
		1468	# used by Impls
		1469	sub _sig_add() {
		1470	unless ($SIG_COUNT++) {
		1471	# try to align timer on a full-second boundary, if possible
		1472	my $NOW = AE::now;
		1473
		1474	$SIG_TW = AE::timer
		1475	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1476	$MAX_SIGNAL_LATENCY,
		1477	sub { } # just for the PERL_ASYNC_CHECK
		1478	;
1102	}	1479	}
1103	}	1480	}
1104		1481
1105	sub time { _time }	1482	sub _sig_del {
1106	sub now { _time }	1483	undef $SIG_TW
1107	sub now_update { }	1484	unless --$SIG_COUNT;
1108
1109	# default implementation for ->condvar
1110
1111	sub condvar {
1112	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1113	}	1485	}
1114		1486
1115	# default implementation for ->signal	1487	our $_sig_name_init; $_sig_name_init = sub {
		1488	eval q{ # poor man's autoloading {}
		1489	undef $_sig_name_init;
1116		1490
1117	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1491	if (_have_async_interrupt) {
		1492	*sig2num = \&Async::Interrupt::sig2num;
		1493	*sig2name = \&Async::Interrupt::sig2name;
		1494	} else {
		1495	require Config;
1118		1496
1119	sub _signal_exec {	1497	my %signame2num;
1120	sysread $SIGPIPE_R, my $dummy, 4;	1498	@signame2num{ split ' ', $Config::Config{sig_name} }
		1499	= split ' ', $Config::Config{sig_num};
1121		1500
1122	while (%SIG_EV) {	1501	my @signum2name;
1123	for (keys %SIG_EV) {	1502	@signum2name[values %signame2num] = keys %signame2num;
1124	delete $SIG_EV{$_};	1503
1125	$_->() for values %{ $SIG_CB{$_} || {} };	1504	*sig2num = sub($) {
		1505	$_[0] > 0 ? shift : $signame2num{+shift}
		1506	};
		1507	*sig2name = sub ($) {
		1508	$_[0] > 0 ? $signum2name[+shift] : shift
		1509	};
1126	}	1510	}
1127	}	1511	};
1128	}	1512	die if $@;
		1513	};
		1514
		1515	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1516	sub sig2name($) { &$_sig_name_init; &sig2name }
1129		1517
1130	sub signal {	1518	sub signal {
1131	my (undef, %arg) = @_;	1519	eval q{ # poor man's autoloading {}
		1520	# probe for availability of Async::Interrupt
		1521	if (_have_async_interrupt) {
		1522	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1132		1523
1133	unless ($SIGPIPE_R) {	1524	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1134	require Fcntl;	1525	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1135		1526
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 {	1527	} else {
		1528	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1529
		1530	if (AnyEvent::WIN32) {
		1531	require AnyEvent::Util;
		1532
		1533	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1534	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1535	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1536	} else {
1143	pipe $SIGPIPE_R, $SIGPIPE_W;	1537	pipe $SIGPIPE_R, $SIGPIPE_W;
1144	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1538	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1145	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1539	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1540
		1541	# not strictly required, as $^F is normally 2, but let's make sure...
		1542	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1543	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1544	}
		1545
		1546	$SIGPIPE_R
		1547	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1548
		1549	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1146	}	1550	}
1147		1551
1148	$SIGPIPE_R	1552	*signal = $HAVE_ASYNC_INTERRUPT
1149	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1553	? sub {
		1554	my (undef, %arg) = @_;
1150		1555
1151	# not strictly required, as $^F is normally 2, but let's make sure...	1556	# 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}	1557	my $signal = sig2num $arg{signal};
1159	or Carp::croak "required option 'signal' is missing";
1160
1161	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1558	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1559
		1560	$SIG_ASY{$signal} ||= new Async::Interrupt
		1561	cb => sub { undef $SIG_EV{$signal} },
		1562	signal => $signal,
		1563	pipe => [$SIGPIPE_R->filenos],
		1564	pipe_autodrain => 0,
		1565	;
		1566
		1567	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1568	}
		1569	: sub {
		1570	my (undef, %arg) = @_;
		1571
		1572	# pure perl
		1573	my $signal = sig2name $arg{signal};
		1574	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1575
1162	$SIG{$signal} ||= sub {	1576	$SIG{$signal} ||= sub {
1163	local $!;	1577	local $!;
1164	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1578	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1165	undef $SIG_EV{$signal};	1579	undef $SIG_EV{$signal};
		1580	};
		1581
		1582	# can't do signal processing without introducing races in pure perl,
		1583	# so limit the signal latency.
		1584	_sig_add;
		1585
		1586	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1587	}
		1588	;
		1589
		1590	*AnyEvent::Base::signal::DESTROY = sub {
		1591	my ($signal, $cb) = @{$_[0]};
		1592
		1593	_sig_del;
		1594
		1595	delete $SIG_CB{$signal}{$cb};
		1596
		1597	$HAVE_ASYNC_INTERRUPT
		1598	? delete $SIG_ASY{$signal}
		1599	: # delete doesn't work with older perls - they then
		1600	# print weird messages, or just unconditionally exit
		1601	# instead of getting the default action.
		1602	undef $SIG{$signal}
		1603	unless keys %{ $SIG_CB{$signal} };
		1604	};
		1605
		1606	*_signal_exec = sub {
		1607	$HAVE_ASYNC_INTERRUPT
		1608	? $SIGPIPE_R->drain
		1609	: sysread $SIGPIPE_R, (my $dummy), 9;
		1610
		1611	while (%SIG_EV) {
		1612	for (keys %SIG_EV) {
		1613	delete $SIG_EV{$_};
		1614	$_->() for values %{ $SIG_CB{$_} || {} };
		1615	}
		1616	}
		1617	};
1166	};	1618	};
		1619	die if $@;
1167		1620
1168	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"	1621	&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	}	1622	}
1178		1623
1179	# default implementation for ->child	1624	# default implementation for ->child
1180		1625
1181	our %PID_CB;	1626	our %PID_CB;
1182	our $CHLD_W;	1627	our $CHLD_W;
1183	our $CHLD_DELAY_W;	1628	our $CHLD_DELAY_W;
1184	our $PID_IDLE;
1185	our $WNOHANG;	1629	our $WNOHANG;
1186		1630
1187	sub _child_wait {	1631	# used by many Impl's
1188	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1632	sub _emit_childstatus($$) {
		1633	my (undef, $rpid, $rstatus) = @_;
		1634
		1635	$_->($rpid, $rstatus)
1189	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1636	for values %{ $PID_CB{$rpid} || {} },
1190	(values %{ $PID_CB{0} || {} });	1637	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	}	1638	}
1203		1639
1204	sub child {	1640	sub child {
		1641	eval q{ # poor man's autoloading {}
		1642	*_sigchld = sub {
		1643	my $pid;
		1644
		1645	AnyEvent->_emit_childstatus ($pid, $?)
		1646	while ($pid = waitpid -1, $WNOHANG) > 0;
		1647	};
		1648
		1649	*child = sub {
1205	my (undef, %arg) = @_;	1650	my (undef, %arg) = @_;
1206		1651
1207	defined (my $pid = $arg{pid} + 0)	1652	defined (my $pid = $arg{pid} + 0)
1208	or Carp::croak "required option 'pid' is missing";	1653	or Carp::croak "required option 'pid' is missing";
1209		1654
1210	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1655	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1211		1656
1212	unless ($WNOHANG) {	1657	# WNOHANG is almost cetrainly 1 everywhere
		1658	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1659	? 1
1213	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1660	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1214	}
1215		1661
1216	unless ($CHLD_W) {	1662	unless ($CHLD_W) {
1217	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1663	$CHLD_W = AE::signal CHLD => \&_sigchld;
1218	# child could be a zombie already, so make at least one round	1664	# child could be a zombie already, so make at least one round
1219	&_sigchld;	1665	&_sigchld;
1220	}	1666	}
1221		1667
1222	bless [$pid, $arg{cb}], "AnyEvent::Base::child"	1668	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1223	}	1669	};
1224		1670
1225	sub AnyEvent::Base::child::DESTROY {	1671	*AnyEvent::Base::child::DESTROY = sub {
1226	my ($pid, $cb) = @{$_[0]};	1672	my ($pid, $cb) = @{$_[0]};
1227		1673
1228	delete $PID_CB{$pid}{$cb};	1674	delete $PID_CB{$pid}{$cb};
1229	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1675	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1230		1676
1231	undef $CHLD_W unless keys %PID_CB;	1677	undef $CHLD_W unless keys %PID_CB;
		1678	};
		1679	};
		1680	die if $@;
		1681
		1682	&child
1232	}	1683	}
1233		1684
1234	# idle emulation is done by simply using a timer, regardless	1685	# idle emulation is done by simply using a timer, regardless
1235	# of whether the proces sis idle or not, and not letting	1686	# of whether the process is idle or not, and not letting
1236	# the callback use more than 50% of the time.	1687	# the callback use more than 50% of the time.
1237	sub idle {	1688	sub idle {
		1689	eval q{ # poor man's autoloading {}
		1690	*idle = sub {
1238	my (undef, %arg) = @_;	1691	my (undef, %arg) = @_;
1239		1692
1240	my ($cb, $w, $rcb) = $arg{cb};	1693	my ($cb, $w, $rcb) = $arg{cb};
1241		1694
1242	$rcb = sub {	1695	$rcb = sub {
1243	if ($cb) {	1696	if ($cb) {
1244	$w = _time;	1697	$w = _time;
1245	&$cb;	1698	&$cb;
1246	$w = _time - $w;	1699	$w = _time - $w;
1247		1700
1248	# never use more then 50% of the time for the idle watcher,	1701	# never use more then 50% of the time for the idle watcher,
1249	# within some limits	1702	# within some limits
1250	$w = 0.0001 if $w < 0.0001;	1703	$w = 0.0001 if $w < 0.0001;
1251	$w = 5 if $w > 5;	1704	$w = 5 if $w > 5;
1252		1705
1253	$w = AnyEvent->timer (after => $w, cb => $rcb);	1706	$w = AE::timer $w, 0, $rcb;
1254	} else {	1707	} else {
1255	# clean up...	1708	# clean up...
1256	undef $w;	1709	undef $w;
1257	undef $rcb;	1710	undef $rcb;
		1711	}
		1712	};
		1713
		1714	$w = AE::timer 0.05, 0, $rcb;
		1715
		1716	bless \\$cb, "AnyEvent::Base::idle"
1258	}	1717	};
		1718
		1719	*AnyEvent::Base::idle::DESTROY = sub {
		1720	undef $${$_[0]};
		1721	};
1259	};	1722	};
		1723	die if $@;
1260		1724
1261	$w = AnyEvent->timer (after => 0.05, cb => $rcb);	1725	&idle
1262
1263	bless \\$cb, "AnyEvent::Base::idle"
1264	}
1265
1266	sub AnyEvent::Base::idle::DESTROY {
1267	undef $${$_[0]};
1268	}	1726	}
1269		1727
1270	package AnyEvent::CondVar;	1728	package AnyEvent::CondVar;
1271		1729
1272	our @ISA = AnyEvent::CondVar::Base::;	1730	our @ISA = AnyEvent::CondVar::Base::;
1273		1731
		1732	# only to be used for subclassing
		1733	sub new {
		1734	my $class = shift;
		1735	bless AnyEvent->condvar (@_), $class
		1736	}
		1737
1274	package AnyEvent::CondVar::Base;	1738	package AnyEvent::CondVar::Base;
1275		1739
1276	use overload	1740	#use overload
1277	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1741	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1278	fallback => 1;	1742	# fallback => 1;
		1743
		1744	# save 300+ kilobytes by dirtily hardcoding overloading
		1745	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1746	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1747	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1748	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1749
		1750	our $WAITING;
1279		1751
1280	sub _send {	1752	sub _send {
1281	# nop	1753	# nop
1282	}	1754	}
1283		1755
…		…
1296	sub ready {	1768	sub ready {
1297	$_[0]{_ae_sent}	1769	$_[0]{_ae_sent}
1298	}	1770	}
1299		1771
1300	sub _wait {	1772	sub _wait {
		1773	$WAITING
		1774	and !$_[0]{_ae_sent}
		1775	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1776
		1777	local $WAITING = 1;
1301	AnyEvent->one_event while !$_[0]{_ae_sent};	1778	AnyEvent->one_event while !$_[0]{_ae_sent};
1302	}	1779	}
1303		1780
1304	sub recv {	1781	sub recv {
1305	$_[0]->_wait;	1782	$_[0]->_wait;
…		…
1307	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1784	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1308	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1785	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1309	}	1786	}
1310		1787
1311	sub cb {	1788	sub cb {
1312	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1789	my $cv = shift;
		1790
		1791	@_
		1792	and $cv->{_ae_cb} = shift
		1793	and $cv->{_ae_sent}
		1794	and (delete $cv->{_ae_cb})->($cv);
		1795
1313	$_[0]{_ae_cb}	1796	$cv->{_ae_cb}
1314	}	1797	}
1315		1798
1316	sub begin {	1799	sub begin {
1317	++$_[0]{_ae_counter};	1800	++$_[0]{_ae_counter};
1318	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1801	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1346	so on.	1829	so on.
1347		1830
1348	=head1 ENVIRONMENT VARIABLES	1831	=head1 ENVIRONMENT VARIABLES
1349		1832
1350	The following environment variables are used by this module or its	1833	The following environment variables are used by this module or its
1351	submodules:	1834	submodules.
		1835
		1836	Note that AnyEvent will remove I<all> environment variables starting with
		1837	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1838	enabled.
1352		1839
1353	=over 4	1840	=over 4
1354		1841
1355	=item C<PERL_ANYEVENT_VERBOSE>	1842	=item C<PERL_ANYEVENT_VERBOSE>
1356		1843
…		…
1363	C<PERL_ANYEVENT_MODEL>.	1850	C<PERL_ANYEVENT_MODEL>.
1364		1851
1365	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1852	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1366	model it chooses.	1853	model it chooses.
1367		1854
		1855	When set to C<8> or higher, then AnyEvent will report extra information on
		1856	which optional modules it loads and how it implements certain features.
		1857
1368	=item C<PERL_ANYEVENT_STRICT>	1858	=item C<PERL_ANYEVENT_STRICT>
1369		1859
1370	AnyEvent does not do much argument checking by default, as thorough	1860	AnyEvent does not do much argument checking by default, as thorough
1371	argument checking is very costly. Setting this variable to a true value	1861	argument checking is very costly. Setting this variable to a true value
1372	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1862	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1373	check the arguments passed to most method calls. If it finds any problems	1863	check the arguments passed to most method calls. If it finds any problems,
1374	it will croak.	1864	it will croak.
1375		1865
1376	In other words, enables "strict" mode.	1866	In other words, enables "strict" mode.
1377		1867
1378	Unlike C<use strict>, it is definitely recommended ot keep it off in	1868	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1379	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1869	>>, it is definitely recommended to keep it off in production. Keeping
1380	developing programs can be very useful, however.	1870	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1871	can be very useful, however.
1381		1872
1382	=item C<PERL_ANYEVENT_MODEL>	1873	=item C<PERL_ANYEVENT_MODEL>
1383		1874
1384	This can be used to specify the event model to be used by AnyEvent, before	1875	This can be used to specify the event model to be used by AnyEvent, before
1385	auto detection and -probing kicks in. It must be a string consisting	1876	auto detection and -probing kicks in. It must be a string consisting
…		…
1428		1919
1429	=item C<PERL_ANYEVENT_MAX_FORKS>	1920	=item C<PERL_ANYEVENT_MAX_FORKS>
1430		1921
1431	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1922	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1432	will create in parallel.	1923	will create in parallel.
		1924
		1925	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1926
		1927	The default value for the C<max_outstanding> parameter for the default DNS
		1928	resolver - this is the maximum number of parallel DNS requests that are
		1929	sent to the DNS server.
		1930
		1931	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1932
		1933	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1934	configuration) in the default resolver. When set to the empty string, no
		1935	default config will be used.
		1936
		1937	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1938
		1939	When neither C<ca_file> nor C<ca_path> was specified during
		1940	L<AnyEvent::TLS> context creation, and either of these environment
		1941	variables exist, they will be used to specify CA certificate locations
		1942	instead of a system-dependent default.
		1943
		1944	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1945
		1946	When these are set to C<1>, then the respective modules are not
		1947	loaded. Mostly good for testing AnyEvent itself.
1433		1948
1434	=back	1949	=back
1435		1950
1436	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1951	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1437		1952
…		…
1495	warn "read: $input\n"; # output what has been read	2010	warn "read: $input\n"; # output what has been read
1496	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2011	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1497	},	2012	},
1498	);	2013	);
1499		2014
1500	my $time_watcher; # can only be used once
1501
1502	sub new_timer {
1503	$timer = AnyEvent->timer (after => 1, cb => sub {	2015	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1504	warn "timeout\n"; # print 'timeout' about every second	2016	warn "timeout\n"; # print 'timeout' at most every second
1505	&new_timer; # and restart the time
1506	});	2017	});
1507	}
1508
1509	new_timer; # create first timer
1510		2018
1511	$cv->recv; # wait until user enters /^q/i	2019	$cv->recv; # wait until user enters /^q/i
1512		2020
1513	=head1 REAL-WORLD EXAMPLE	2021	=head1 REAL-WORLD EXAMPLE
1514		2022
…		…
1587		2095
1588	The actual code goes further and collects all errors (C<die>s, exceptions)	2096	The actual code goes further and collects all errors (C<die>s, exceptions)
1589	that occurred during request processing. The C<result> method detects	2097	that occurred during request processing. The C<result> method detects
1590	whether an exception as thrown (it is stored inside the $txn object)	2098	whether an exception as thrown (it is stored inside the $txn object)
1591	and just throws the exception, which means connection errors and other	2099	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	2100	problems get reported to the code that tries to use the result, not in a
1593	random callback.	2101	random callback.
1594		2102
1595	All of this enables the following usage styles:	2103	All of this enables the following usage styles:
1596		2104
1597	1. Blocking:	2105	1. Blocking:
…		…
1645	through AnyEvent. The benchmark creates a lot of timers (with a zero	2153	through AnyEvent. The benchmark creates a lot of timers (with a zero
1646	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2154	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1647	which it is), lets them fire exactly once and destroys them again.	2155	which it is), lets them fire exactly once and destroys them again.
1648		2156
1649	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2157	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1650	distribution.	2158	distribution. It uses the L<AE> interface, which makes a real difference
		2159	for the EV and Perl backends only.
1651		2160
1652	=head3 Explanation of the columns	2161	=head3 Explanation of the columns
1653		2162
1654	I<watcher> is the number of event watchers created/destroyed. Since	2163	I<watcher> is the number of event watchers created/destroyed. Since
1655	different event models feature vastly different performances, each event	2164	different event models feature vastly different performances, each event
…		…
1676	watcher.	2185	watcher.
1677		2186
1678	=head3 Results	2187	=head3 Results
1679		2188
1680	name watchers bytes create invoke destroy comment	2189	name watchers bytes create invoke destroy comment
1681	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2190	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1682	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2191	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1683	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2192	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1684	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2193	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1685	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2194	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1686	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2195	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2196	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2197	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1687	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2198	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1688	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2199	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1689	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2200	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1690	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2201	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1691		2202
1692	=head3 Discussion	2203	=head3 Discussion
1693		2204
1694	The benchmark does I<not> measure scalability of the event loop very	2205	The benchmark does I<not> measure scalability of the event loop very
1695	well. For example, a select-based event loop (such as the pure perl one)	2206	well. For example, a select-based event loop (such as the pure perl one)
…		…
1707	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2218	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	2219	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1709	cycles with POE.	2220	cycles with POE.
1710		2221
1711	C<EV> is the sole leader regarding speed and memory use, which are both	2222	C<EV> is the sole leader regarding speed and memory use, which are both
1712	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2223	maximal/minimal, respectively. When using the L<AE> API there is zero
		2224	overhead (when going through the AnyEvent API create is about 5-6 times
		2225	slower, with other times being equal, so still uses far less memory than
1713	far less memory than any other event loop and is still faster than Event	2226	any other event loop and is still faster than Event natively).
1714	natively.
1715		2227
1716	The pure perl implementation is hit in a few sweet spots (both the	2228	The pure perl implementation is hit in a few sweet spots (both the
1717	constant timeout and the use of a single fd hit optimisations in the perl	2229	constant timeout and the use of a single fd hit optimisations in the perl
1718	interpreter and the backend itself). Nevertheless this shows that it	2230	interpreter and the backend itself). Nevertheless this shows that it
1719	adds very little overhead in itself. Like any select-based backend its	2231	adds very little overhead in itself. Like any select-based backend its
1720	performance becomes really bad with lots of file descriptors (and few of	2232	performance becomes really bad with lots of file descriptors (and few of
1721	them active), of course, but this was not subject of this benchmark.	2233	them active), of course, but this was not subject of this benchmark.
1722		2234
1723	The C<Event> module has a relatively high setup and callback invocation	2235	The C<Event> module has a relatively high setup and callback invocation
1724	cost, but overall scores in on the third place.	2236	cost, but overall scores in on the third place.
		2237
		2238	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2239	when using its pure perl backend.
1725		2240
1726	C<Glib>'s memory usage is quite a bit higher, but it features a	2241	C<Glib>'s memory usage is quite a bit higher, but it features a
1727	faster callback invocation and overall ends up in the same class as	2242	faster callback invocation and overall ends up in the same class as
1728	C<Event>. However, Glib scales extremely badly, doubling the number of	2243	C<Event>. However, Glib scales extremely badly, doubling the number of
1729	watchers increases the processing time by more than a factor of four,	2244	watchers increases the processing time by more than a factor of four,
…		…
1790	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2305	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1791	(1%) are active. This mirrors the activity of large servers with many	2306	(1%) are active. This mirrors the activity of large servers with many
1792	connections, most of which are idle at any one point in time.	2307	connections, most of which are idle at any one point in time.
1793		2308
1794	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2309	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1795	distribution.	2310	distribution. It uses the L<AE> interface, which makes a real difference
		2311	for the EV and Perl backends only.
1796		2312
1797	=head3 Explanation of the columns	2313	=head3 Explanation of the columns
1798		2314
1799	I<sockets> is the number of sockets, and twice the number of "servers" (as	2315	I<sockets> is the number of sockets, and twice the number of "servers" (as
1800	each server has a read and write socket end).	2316	each server has a read and write socket end).
…		…
1807	it to another server. This includes deleting the old timeout and creating	2323	it to another server. This includes deleting the old timeout and creating
1808	a new one that moves the timeout into the future.	2324	a new one that moves the timeout into the future.
1809		2325
1810	=head3 Results	2326	=head3 Results
1811		2327
1812	name sockets create request	2328	name sockets create request
1813	EV 20000 69.01 11.16	2329	EV 20000 62.66 7.99
1814	Perl 20000 73.32 35.87	2330	Perl 20000 68.32 32.64
1815	Event 20000 212.62 257.32	2331	IOAsync 20000 174.06 101.15 epoll
1816	Glib 20000 651.16 1896.30	2332	IOAsync 20000 174.67 610.84 poll
		2333	Event 20000 202.69 242.91
		2334	Glib 20000 557.01 1689.52
1817	POE 20000 349.67 12317.24 uses POE::Loop::Event	2335	POE 20000 341.54 12086.32 uses POE::Loop::Event
1818		2336
1819	=head3 Discussion	2337	=head3 Discussion
1820		2338
1821	This benchmark I<does> measure scalability and overall performance of the	2339	This benchmark I<does> measure scalability and overall performance of the
1822	particular event loop.	2340	particular event loop.
…		…
1824	EV is again fastest. Since it is using epoll on my system, the setup time	2342	EV is again fastest. Since it is using epoll on my system, the setup time
1825	is relatively high, though.	2343	is relatively high, though.
1826		2344
1827	Perl surprisingly comes second. It is much faster than the C-based event	2345	Perl surprisingly comes second. It is much faster than the C-based event
1828	loops Event and Glib.	2346	loops Event and Glib.
		2347
		2348	IO::Async performs very well when using its epoll backend, and still quite
		2349	good compared to Glib when using its pure perl backend.
1829		2350
1830	Event suffers from high setup time as well (look at its code and you will	2351	Event suffers from high setup time as well (look at its code and you will
1831	understand why). Callback invocation also has a high overhead compared to	2352	understand why). Callback invocation also has a high overhead compared to
1832	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2353	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1833	uses select or poll in basically all documented configurations.	2354	uses select or poll in basically all documented configurations.
…		…
1896	=item * C-based event loops perform very well with small number of	2417	=item * C-based event loops perform very well with small number of
1897	watchers, as the management overhead dominates.	2418	watchers, as the management overhead dominates.
1898		2419
1899	=back	2420	=back
1900		2421
		2422	=head2 THE IO::Lambda BENCHMARK
		2423
		2424	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2425	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2426	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2427	shouldn't come as a surprise to anybody). As such, the benchmark is
		2428	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2429	very optimal. But how would AnyEvent compare when used without the extra
		2430	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2431
		2432	The benchmark itself creates an echo-server, and then, for 500 times,
		2433	connects to the echo server, sends a line, waits for the reply, and then
		2434	creates the next connection. This is a rather bad benchmark, as it doesn't
		2435	test the efficiency of the framework or much non-blocking I/O, but it is a
		2436	benchmark nevertheless.
		2437
		2438	name runtime
		2439	Lambda/select 0.330 sec
		2440	+ optimized 0.122 sec
		2441	Lambda/AnyEvent 0.327 sec
		2442	+ optimized 0.138 sec
		2443	Raw sockets/select 0.077 sec
		2444	POE/select, components 0.662 sec
		2445	POE/select, raw sockets 0.226 sec
		2446	POE/select, optimized 0.404 sec
		2447
		2448	AnyEvent/select/nb 0.085 sec
		2449	AnyEvent/EV/nb 0.068 sec
		2450	+state machine 0.134 sec
		2451
		2452	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2453	benchmarks actually make blocking connects and use 100% blocking I/O,
		2454	defeating the purpose of an event-based solution. All of the newly
		2455	written AnyEvent benchmarks use 100% non-blocking connects (using
		2456	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2457	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2458	generally require a lot more bookkeeping and event handling than blocking
		2459	connects (which involve a single syscall only).
		2460
		2461	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2462	offers similar expressive power as POE and IO::Lambda, using conventional
		2463	Perl syntax. This means that both the echo server and the client are 100%
		2464	non-blocking, further placing it at a disadvantage.
		2465
		2466	As you can see, the AnyEvent + EV combination even beats the
		2467	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2468	backend easily beats IO::Lambda and POE.
		2469
		2470	And even the 100% non-blocking version written using the high-level (and
		2471	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2472	higher level ("unoptimised") abstractions by a large margin, even though
		2473	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2474
		2475	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2476	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2477	part of the IO::Lambda distribution and were used without any changes.
		2478
1901		2479
1902	=head1 SIGNALS	2480	=head1 SIGNALS
1903		2481
1904	AnyEvent currently installs handlers for these signals:	2482	AnyEvent currently installs handlers for these signals:
1905		2483
…		…
1908	=item SIGCHLD	2486	=item SIGCHLD
1909		2487
1910	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2488	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1911	emulation for event loops that do not support them natively. Also, some	2489	emulation for event loops that do not support them natively. Also, some
1912	event loops install a similar handler.	2490	event loops install a similar handler.
		2491
		2492	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2493	AnyEvent will reset it to default, to avoid losing child exit statuses.
1913		2494
1914	=item SIGPIPE	2495	=item SIGPIPE
1915		2496
1916	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2497	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1917	when AnyEvent gets loaded.	2498	when AnyEvent gets loaded.
…		…
1929		2510
1930	=back	2511	=back
1931		2512
1932	=cut	2513	=cut
1933		2514
		2515	undef $SIG{CHLD}
		2516	if $SIG{CHLD} eq 'IGNORE';
		2517
1934	$SIG{PIPE} = sub { }	2518	$SIG{PIPE} = sub { }
1935	unless defined $SIG{PIPE};	2519	unless defined $SIG{PIPE};
1936		2520
		2521	=head1 RECOMMENDED/OPTIONAL MODULES
		2522
		2523	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2524	its built-in modules) are required to use it.
		2525
		2526	That does not mean that AnyEvent won't take advantage of some additional
		2527	modules if they are installed.
		2528
		2529	This section explains which additional modules will be used, and how they
		2530	affect AnyEvent's operation.
		2531
		2532	=over 4
		2533
		2534	=item L<Async::Interrupt>
		2535
		2536	This slightly arcane module is used to implement fast signal handling: To
		2537	my knowledge, there is no way to do completely race-free and quick
		2538	signal handling in pure perl. To ensure that signals still get
		2539	delivered, AnyEvent will start an interval timer to wake up perl (and
		2540	catch the signals) with some delay (default is 10 seconds, look for
		2541	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2542
		2543	If this module is available, then it will be used to implement signal
		2544	catching, which means that signals will not be delayed, and the event loop
		2545	will not be interrupted regularly, which is more efficient (and good for
		2546	battery life on laptops).
		2547
		2548	This affects not just the pure-perl event loop, but also other event loops
		2549	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2550
		2551	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2552	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2553	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2554	does nothing for those backends.
		2555
		2556	=item L<EV>
		2557
		2558	This module isn't really "optional", as it is simply one of the backend
		2559	event loops that AnyEvent can use. However, it is simply the best event
		2560	loop available in terms of features, speed and stability: It supports
		2561	the AnyEvent API optimally, implements all the watcher types in XS, does
		2562	automatic timer adjustments even when no monotonic clock is available,
		2563	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2564	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2565	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2566
		2567	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2568	then this module will do nothing for you.
		2569
		2570	=item L<Guard>
		2571
		2572	The guard module, when used, will be used to implement
		2573	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2574	lot less memory), but otherwise doesn't affect guard operation much. It is
		2575	purely used for performance.
		2576
		2577	=item L<JSON> and L<JSON::XS>
		2578
		2579	One of these modules is required when you want to read or write JSON data
		2580	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2581	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2582
		2583	=item L<Net::SSLeay>
		2584
		2585	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2586	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2587	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2588
		2589	=item L<Time::HiRes>
		2590
		2591	This module is part of perl since release 5.008. It will be used when the
		2592	chosen event library does not come with a timing source of its own. The
		2593	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2594	try to use a monotonic clock for timing stability.
		2595
		2596	=back
		2597
1937		2598
1938	=head1 FORK	2599	=head1 FORK
1939		2600
1940	Most event libraries are not fork-safe. The ones who are usually are	2601	Most event libraries are not fork-safe. The ones who are usually are
1941	because they rely on inefficient but fork-safe C<select> or C<poll>	2602	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1942	calls. Only L<EV> is fully fork-aware.	2603	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2604	are usually badly thought-out hacks that are incompatible with fork in
		2605	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2606	continue event-processing in both parent and child (or both, if you know
		2607	what you are doing).
		2608
		2609	This means that, in general, you cannot fork and do event processing in
		2610	the child if the event library was initialised before the fork (which
		2611	usually happens when the first AnyEvent watcher is created, or the library
		2612	is loaded).
1943		2613
1944	If you have to fork, you must either do so I<before> creating your first	2614	If you have to fork, you must either do so I<before> creating your first
1945	watcher OR you must not use AnyEvent at all in the child.	2615	watcher OR you must not use AnyEvent at all in the child OR you must do
		2616	something completely out of the scope of AnyEvent.
		2617
		2618	The problem of doing event processing in the parent I<and> the child
		2619	is much more complicated: even for backends that I<are> fork-aware or
		2620	fork-safe, their behaviour is not usually what you want: fork clones all
		2621	watchers, that means all timers, I/O watchers etc. are active in both
		2622	parent and child, which is almost never what you want. USing C<exec>
		2623	to start worker children from some kind of manage rprocess is usually
		2624	preferred, because it is much easier and cleaner, at the expense of having
		2625	to have another binary.
1946		2626
1947		2627
1948	=head1 SECURITY CONSIDERATIONS	2628	=head1 SECURITY CONSIDERATIONS
1949		2629
1950	AnyEvent can be forced to load any event model via	2630	AnyEvent can be forced to load any event model via
…		…
1962	use AnyEvent;	2642	use AnyEvent;
1963		2643
1964	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2644	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	2645	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	2646	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1967	$ENV{PERL_ANYEGENT_STRICT}.	2647	$ENV{PERL_ANYEVENT_STRICT}.
		2648
		2649	Note that AnyEvent will remove I<all> environment variables starting with
		2650	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2651	enabled.
1968		2652
1969		2653
1970	=head1 BUGS	2654	=head1 BUGS
1971		2655
1972	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2656	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
…		…
1976	pronounced).	2660	pronounced).
1977		2661
1978		2662
1979	=head1 SEE ALSO	2663	=head1 SEE ALSO
1980		2664
		2665	Tutorial/Introduction: L<AnyEvent::Intro>.
		2666
		2667	FAQ: L<AnyEvent::FAQ>.
		2668
1981	Utility functions: L<AnyEvent::Util>.	2669	Utility functions: L<AnyEvent::Util>.
1982		2670
1983	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2671	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1984	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2672	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1985		2673
1986	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2674	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1987	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2675	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1988	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2676	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1989	L<AnyEvent::Impl::POE>.	2677	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1990		2678
1991	Non-blocking file handles, sockets, TCP clients and	2679	Non-blocking file handles, sockets, TCP clients and
1992	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2680	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1993		2681
1994	Asynchronous DNS: L<AnyEvent::DNS>.	2682	Asynchronous DNS: L<AnyEvent::DNS>.
1995		2683
1996	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2684	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1997		2685
1998	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2686	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2687	L<AnyEvent::HTTP>.
1999		2688
2000		2689
2001	=head1 AUTHOR	2690	=head1 AUTHOR
2002		2691
2003	Marc Lehmann <schmorp@schmorp.de>	2692	Marc Lehmann <schmorp@schmorp.de>

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