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Revision 1.196 by root, Thu Mar 26 07:47:42 2009 UTC vs.
Revision 1.343 by root, Wed Dec 29 04:27:53 2010 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# if you prefer function calls, look at the AE manpage for
		13	# an alternative API.
		14
		15	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
12		17
		18	# one-shot or repeating timers
13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
15		21
16	print AnyEvent->now; # prints current event loop time	22	print AnyEvent->now; # prints current event loop time
17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18		24
		25	# POSIX signal
19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });	26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20		27
		28	# child process exit
21	my $w = AnyEvent->child (pid => $pid, cb => sub {	29	my $w = AnyEvent->child (pid => $pid, cb => sub {
22	my ($pid, $status) = @_;	30	my ($pid, $status) = @_;
23	...	31	...
24	});	32	});
		33
		34	# called when event loop idle (if applicable)
		35	my $w = AnyEvent->idle (cb => sub { ... });
25		36
26	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
27	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
28	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
29	# use a condvar in callback mode:	40	# use a condvar in callback mode:
…		…
32	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
33		44
34	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
35	in a tutorial or some gentle introduction, have a look at the	46	in a tutorial or some gentle introduction, have a look at the
36	L<AnyEvent::Intro> manpage.	47	L<AnyEvent::Intro> manpage.
		48
		49	=head1 SUPPORT
		50
		51	An FAQ document is available as L<AnyEvent::FAQ>.
		52
		53	There also is a mailinglist for discussing all things AnyEvent, and an IRC
		54	channel, too.
		55
		56	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		57	Repository>, at L<http://anyevent.schmorp.de>, for more info.
37		58
38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
39		60
40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	61	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
41	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
…		…
57	module users into the same thing by forcing them to use the same event	78	module users into the same thing by forcing them to use the same event
58	model you use.	79	model you use.
59		80
60	For modules like POE or IO::Async (which is a total misnomer as it is	81	For modules like POE or IO::Async (which is a total misnomer as it is
61	actually doing all I/O I<synchronously>...), using them in your module is	82	actually doing all I/O I<synchronously>...), using them in your module is
62	like joining a cult: After you joined, you are dependent on them and you	83	like joining a cult: After you join, you are dependent on them and you
63	cannot use anything else, as they are simply incompatible to everything	84	cannot use anything else, as they are simply incompatible to everything
64	that isn't them. What's worse, all the potential users of your	85	that isn't them. What's worse, all the potential users of your
65	module are I<also> forced to use the same event loop you use.	86	module are I<also> forced to use the same event loop you use.
66		87
67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
68	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	89	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
69	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	90	with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
70	your module uses one of those, every user of your module has to use it,	91	uses one of those, every user of your module has to use it, too. But if
71	too. But if your module uses AnyEvent, it works transparently with all	92	your module uses AnyEvent, it works transparently with all event models it
72	event models it supports (including stuff like IO::Async, as long as those	93	supports (including stuff like IO::Async, as long as those use one of the
73	use one of the supported event loops. It is trivial to add new event loops	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
74	to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
75		96
76	In addition to being free of having to use I<the one and only true event	97	In addition to being free of having to use I<the one and only true event
77	model>, AnyEvent also is free of bloat and policy: with POE or similar	98	model>, AnyEvent also is free of bloat and policy: with POE or similar
78	modules, you get an enormous amount of code and strict rules you have to	99	modules, you get an enormous amount of code and strict rules you have to
79	follow. AnyEvent, on the other hand, is lean and up to the point, by only	100	follow. AnyEvent, on the other hand, is lean and to the point, by only
80	offering the functionality that is necessary, in as thin as a wrapper as	101	offering the functionality that is necessary, in as thin as a wrapper as
81	technically possible.	102	technically possible.
82		103
83	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
84	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
90	useful) and you want to force your users to use the one and only event	111	useful) and you want to force your users to use the one and only event
91	model, you should I<not> use this module.	112	model, you should I<not> use this module.
92		113
93	=head1 DESCRIPTION	114	=head1 DESCRIPTION
94		115
95	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
96	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
97	users to use the same event loop (as only a single event loop can coexist	118	module users to use a specific event loop implementation (since more
98	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
99		120
100	The interface itself is vaguely similar, but not identical to the L<Event>	121	The interface itself is vaguely similar, but not identical to the L<Event>
101	module.	122	module.
102		123
103	During the first call of any watcher-creation method, the module tries	124	During the first call of any watcher-creation method, the module tries
104	to detect the currently loaded event loop by probing whether one of the	125	to detect the currently loaded event loop by probing whether one of the
105	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Impl::Perl>,
106	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	127	L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
107	L<POE>. The first one found is used. If none are found, the module tries	128	found is used. If none are detected, the module tries to load the first
108	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	129	four modules in the order given; but note that if L<EV> is not
109	adaptor should always succeed) in the order given. The first one that can	130	available, the pure-perl L<AnyEvent::Impl::Perl> should always work, so
110	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
111	found, AnyEvent will fall back to a pure-perl event loop, which is not
112	very efficient, but should work everywhere.
113		132
114	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
115	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
116	that model the default. For example:	135	that model the default. For example:
117		136
…		…
119	use AnyEvent;	138	use AnyEvent;
120		139
121	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
122		141
123	The I<likely> means that, if any module loads another event model and	142	The I<likely> means that, if any module loads another event model and
124	starts using it, all bets are off. Maybe you should tell their authors to	143	starts using it, all bets are off - this case should be very rare though,
125	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
126		146
127	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called
128	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	148	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
129	explicitly and enjoy the high availability of that event loop :)	149	explicitly and enjoy the high availability of that event loop :)
130		150
…		…
139	callback when the event occurs (of course, only when the event model	159	callback when the event occurs (of course, only when the event model
140	is in control).	160	is in control).
141		161
142	Note that B<callbacks must not permanently change global variables>	162	Note that B<callbacks must not permanently change global variables>
143	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<<
144	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
145	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
146	widely between event loops.	166	widely between event loops.
147		167
148	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
149	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
150	to it).	170	to it).
151		171
152	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.
153		173
154	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
155	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.
156		176
157	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
158		178
159	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
160	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
161	undef $w;	181	undef $w;
162	});	182	});
…		…
165	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
166	declared.	186	declared.
167		187
168	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
169		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
170	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
171	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
172		198
173	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
174	(AnyEvent might or might not keep a reference to this file handle). C<poll>	200	for events (AnyEvent might or might not keep a reference to this file
		201	handle). Note that only file handles pointing to things for which
		202	non-blocking operation makes sense are allowed. This includes sockets,
		203	most character devices, pipes, fifos and so on, but not for example files
		204	or block devices.
		205
175	must be a string that is either C<r> or C<w>, which creates a watcher	206	C<poll> must be a string that is either C<r> or C<w>, which creates a
176	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
177	callback to invoke each time the file handle becomes ready.	209	C<cb> is the callback to invoke each time the file handle becomes ready.
178		210
179	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
180	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
181	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
182		214
183	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.
184	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
185	underlying file descriptor.	217	underlying file descriptor.
186		218
187	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
188	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
189	handles.	221	handles.
190		222
191	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
192	watcher.	224	watcher.
…		…
197	undef $w;	229	undef $w;
198	});	230	});
199		231
200	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
201		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
202	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 >>
203	method with the following mandatory arguments:	243	method with the following mandatory arguments:
204		244
205	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
206	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
…		…
208		248
209	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
210	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
211	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
212		252
213	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
214	parameter, C<interval>, as a strictly positive number (> 0), then the	254	parameter, C<interval>, as a strictly positive number (> 0), then the
215	callback will be invoked regularly at that interval (in fractional	255	callback will be invoked regularly at that interval (in fractional
216	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
217	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.
218		258
219	The callback will be rescheduled before invoking the callback, but no	259	The callback will be rescheduled before invoking the callback, but no
220	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
221	only approximate.	261	only approximate.
222		262
223	Example: fire an event after 7.7 seconds.	263	Example: fire an event after 7.7 seconds.
224		264
225	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
243		283
244	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
245	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
246	"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
247	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
248	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.
249		289
250	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
251	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
252	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)
253	timers.	293	timers.
254		294
255	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
256	AnyEvent API.	296	AnyEvent API.
…		…
278	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
279	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
280		320
281	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
282	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
283	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
284		324
285	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
286	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
287		327
288	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>
289	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
290		330
291	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
292	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
293	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
294	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
295	after three seconds.	335	after three seconds.
296		336
…		…
314	In either case, if you care (and in most cases, you don't), then you	354	In either case, if you care (and in most cases, you don't), then you
315	can get whatever behaviour you want with any event loop, by taking the	355	can get whatever behaviour you want with any event loop, by taking the
316	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
317	account.	357	account.
318		358
		359	=item AnyEvent->now_update
		360
		361	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		362	the current time for each loop iteration (see the discussion of L<<
		363	AnyEvent->now >>, above).
		364
		365	When a callback runs for a long time (or when the process sleeps), then
		366	this "current" time will differ substantially from the real time, which
		367	might affect timers and time-outs.
		368
		369	When this is the case, you can call this method, which will update the
		370	event loop's idea of "current time".
		371
		372	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		373	when mod_perl executes the script, then the event loop will have the wrong
		374	idea about the "current time" (being potentially far in the past, when the
		375	script ran the last time). In that case you should arrange a call to C<<
		376	AnyEvent->now_update >> each time the web server process wakes up again
		377	(e.g. at the start of your script, or in a handler).
		378
		379	Note that updating the time I<might> cause some events to be handled.
		380
319	=back	381	=back
320		382
321	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
322		386
323	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
324	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
325	callback to be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
326		390
…		…
332	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
333	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,
334	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
335		399
336	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
337	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
338		403
339	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
340	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
341		407
342	Example: exit on SIGINT	408	Example: exit on SIGINT
343		409
344	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
345		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$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
346	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
347		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
348	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.
349		454
350	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,
351	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
352	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
353	any trace events (stopped/continued).	458	finished and an exit status is available, not on any trace events
		459	(stopped/continued).
354		460
355	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
356	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
357	callback arguments.	463	callback arguments.
358		464
…		…
363		469
364	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
365	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
366	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
367		473
368	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
369	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
370	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.
371		480
372	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
373	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
374	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.
375		489
376	Example: fork a process and wait for it	490	Example: fork a process and wait for it
377		491
378	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
379		493
…		…
389	);	503	);
390		504
391	# do something else, then wait for process exit	505	# do something else, then wait for process exit
392	$done->recv;	506	$done->recv;
393		507
		508	=head2 IDLE WATCHERS
		509
		510	$w = AnyEvent->idle (cb => <callback>);
		511
		512	This will repeatedly invoke the callback after the process becomes idle,
		513	until either the watcher is destroyed or new events have been detected.
		514
		515	Idle watchers are useful when there is a need to do something, but it
		516	is not so important (or wise) to do it instantly. The callback will be
		517	invoked only when there is "nothing better to do", which is usually
		518	defined as "all outstanding events have been handled and no new events
		519	have been detected". That means that idle watchers ideally get invoked
		520	when the event loop has just polled for new events but none have been
		521	detected. Instead of blocking to wait for more events, the idle watchers
		522	will be invoked.
		523
		524	Unfortunately, most event loops do not really support idle watchers (only
		525	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		526	will simply call the callback "from time to time".
		527
		528	Example: read lines from STDIN, but only process them when the
		529	program is otherwise idle:
		530
		531	my @lines; # read data
		532	my $idle_w;
		533	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		534	push @lines, scalar <STDIN>;
		535
		536	# start an idle watcher, if not already done
		537	$idle_w ||= AnyEvent->idle (cb => sub {
		538	# handle only one line, when there are lines left
		539	if (my $line = shift @lines) {
		540	print "handled when idle: $line";
		541	} else {
		542	# otherwise disable the idle watcher again
		543	undef $idle_w;
		544	}
		545	});
		546	});
		547
394	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
395		554
396	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
397	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
398	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
399		558
400	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
401	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).
402		561
403	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
404	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.
405		566
406	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
407	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
408
409	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
410	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
411	the results).	571	the results).
412		572
413	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
414	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
415	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<<
416	->send >> method).	576	->send >> method).
417		577
418	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
419	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:
420	in time where multiple outstanding events have been processed. And yet	580
421	another way to call them is transactions - each condition variable can be	581	=over 4
422	used to represent a transaction, which finishes at some point and delivers	582
423	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
424		601
425	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
426	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,
427	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
428	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
…		…
441		618
442	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
443	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
444	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
445	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
446	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
447		624
448	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
449	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
450	for the send to occur.	627	for the send to occur.
451		628
452	Example: wait for a timer.	629	Example: wait for a timer.
453		630
454	# wait till the result is ready	631	# condition: "wait till the timer is fired"
455	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
456		633
457	# do something such as adding a timer	634	# create the timer - we could wait for, say
458	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
459	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
460	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
461	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
462	after => 1,	639	after => 1,
463	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
464	);	641	);
465		642
466	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
467	# calls send	644	# calls ->send
468	$result_ready->recv;	645	$timer_fired->recv;
469		646
470	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
471	condition variables are also code references.	648	variables are also callable directly.
472		649
473	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
474	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
475	$done->recv;	652	$done->recv;
476		653
…		…
482		659
483	...	660	...
484		661
485	my @info = $couchdb->info->recv;	662	my @info = $couchdb->info->recv;
486		663
487	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
488	results are available:	665	results are available:
489		666
490	$couchdb->info->cb (sub {	667	$couchdb->info->cb (sub {
491	my @info = $_[0]->recv;	668	my @info = $_[0]->recv;
492	});	669	});
…		…
510	immediately from within send.	687	immediately from within send.
511		688
512	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
513	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
514		691
515	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
516	(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
517	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
518	overloading, so as tempting as it may be, passing a condition variable
519	instead of a callback does not work. Both the pure perl and EV loops
520	support overloading, however, as well as all functions that use perl to
521	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
522	example).
523		695
524	=item $cv->croak ($error)	696	=item $cv->croak ($error)
525		697
526	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
527	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
528		700
529	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
530	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.
531		707
532	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
533		709
534	=item $cv->end	710	=item $cv->end
535
536	These two methods are EXPERIMENTAL and MIGHT CHANGE.
537		711
538	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
539	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
540	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
541		715
542	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
543	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
544	>>, 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
545	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
546	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.
547		722
548	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:
549		730
550	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
551		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
552	my %result;	757	my %result;
553	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
554		759
555	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
556	$cv->begin;	761	$cv->begin;
557	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
558	$result{$host} = ...;	763	$result{$host} = ...;
…		…
573	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
574	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
575	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
576	doesn't execute once).	781	doesn't execute once).
577		782
578	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
579	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
580	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
581	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>.
582		788
583	=back	789	=back
584		790
585	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
586		792
…		…
590	=over 4	796	=over 4
591		797
592	=item $cv->recv	798	=item $cv->recv
593		799
594	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
595	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
596	normally.	802	normally.
597		803
598	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
599	will return immediately.	805	will return immediately.
600		806
…		…
602	function will call C<croak>.	808	function will call C<croak>.
603		809
604	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,
605	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
606		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
607	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
608	(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
609	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
610	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
611	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
612	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,
613	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
614		827
615	Another reason I<never> to C<< ->recv >> in a module is that you cannot
616	sensibly have two C<< ->recv >>'s in parallel, as that would require
617	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
618	can supply.
619
620	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
621	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
622	versions and also integrates coroutines into AnyEvent, making blocking
623	C<< ->recv >> calls perfectly safe as long as they are done from another
624	coroutine (one that doesn't run the event loop).
625
626	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
627	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
628	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
629	waits otherwise.	831	waits otherwise.
630		832
631	=item $bool = $cv->ready	833	=item $bool = $cv->ready
…		…
637		839
638	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
639	replaces it before doing so.	841	replaces it before doing so.
640		842
641	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
642	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
643	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
644	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.
645		848
646	=back	849	=back
647		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	AnyEvent::Impl::IOAsync based on IO::Async.
		882
		883	=item Backends with special needs.
		884
		885	Qt requires the Qt::Application to be instantiated first, but will
		886	otherwise be picked up automatically. As long as the main program
		887	instantiates the application before any AnyEvent watchers are created,
		888	everything should just work.
		889
		890	AnyEvent::Impl::Qt based on Qt.
		891
		892	=item Event loops that are indirectly supported via other backends.
		893
		894	Some event loops can be supported via other modules:
		895
		896	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		897
		898	B<WxWidgets> has no support for watching file handles. However, you can
		899	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		900	polls 20 times per second, which was considered to be too horrible to even
		901	consider for AnyEvent.
		902
		903	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		904	backend, so it can be supported through POE.
		905
		906	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		907	load L<POE> when detecting them, in the hope that POE will pick them up,
		908	in which case everything will be automatic.
		909
		910	=back
		911
648	=head1 GLOBAL VARIABLES AND FUNCTIONS	912	=head1 GLOBAL VARIABLES AND FUNCTIONS
649		913
		914	These are not normally required to use AnyEvent, but can be useful to
		915	write AnyEvent extension modules.
		916
650	=over 4	917	=over 4
651		918
652	=item $AnyEvent::MODEL	919	=item $AnyEvent::MODEL
653		920
654	Contains C<undef> until the first watcher is being created. Then it	921	Contains C<undef> until the first watcher is being created, before the
		922	backend has been autodetected.
		923
655	contains the event model that is being used, which is the name of the	924	Afterwards it contains the event model that is being used, which is the
656	Perl class implementing the model. This class is usually one of the	925	name of the Perl class implementing the model. This class is usually one
657	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	926	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
658	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	927	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
659		928	will be C<urxvt::anyevent>).
660	The known classes so far are:
661
662	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
663	AnyEvent::Impl::Event based on Event, second best choice.
664	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
665	AnyEvent::Impl::Glib based on Glib, third-best choice.
666	AnyEvent::Impl::Tk based on Tk, very bad choice.
667	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
668	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
669	AnyEvent::Impl::POE based on POE, not generic enough for full support.
670
671	There is no support for WxWidgets, as WxWidgets has no support for
672	watching file handles. However, you can use WxWidgets through the
673	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
674	second, which was considered to be too horrible to even consider for
675	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
676	it's adaptor.
677
678	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
679	autodetecting them.
680		929
681	=item AnyEvent::detect	930	=item AnyEvent::detect
682		931
683	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	932	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
684	if necessary. You should only call this function right before you would	933	if necessary. You should only call this function right before you would
685	have created an AnyEvent watcher anyway, that is, as late as possible at	934	have created an AnyEvent watcher anyway, that is, as late as possible at
686	runtime.	935	runtime, and not e.g. during initialisation of your module.
		936
		937	If you need to do some initialisation before AnyEvent watchers are
		938	created, use C<post_detect>.
687		939
688	=item $guard = AnyEvent::post_detect { BLOCK }	940	=item $guard = AnyEvent::post_detect { BLOCK }
689		941
690	Arranges for the code block to be executed as soon as the event model is	942	Arranges for the code block to be executed as soon as the event model is
691	autodetected (or immediately if this has already happened).	943	autodetected (or immediately if that has already happened).
		944
		945	The block will be executed I<after> the actual backend has been detected
		946	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		947	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		948	other initialisations - see the sources of L<AnyEvent::Strict> or
		949	L<AnyEvent::AIO> to see how this is used.
		950
		951	The most common usage is to create some global watchers, without forcing
		952	event module detection too early, for example, L<AnyEvent::AIO> creates
		953	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		954	avoid autodetecting the event module at load time.
692		955
693	If called in scalar or list context, then it creates and returns an object	956	If called in scalar or list context, then it creates and returns an object
694	that automatically removes the callback again when it is destroyed. See	957	that automatically removes the callback again when it is destroyed (or
		958	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
695	L<Coro::BDB> for a case where this is useful.	959	a case where this is useful.
		960
		961	Example: Create a watcher for the IO::AIO module and store it in
		962	C<$WATCHER>, but do so only do so after the event loop is initialised.
		963
		964	our WATCHER;
		965
		966	my $guard = AnyEvent::post_detect {
		967	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		968	};
		969
		970	# the ||= is important in case post_detect immediately runs the block,
		971	# as to not clobber the newly-created watcher. assigning both watcher and
		972	# post_detect guard to the same variable has the advantage of users being
		973	# able to just C<undef $WATCHER> if the watcher causes them grief.
		974
		975	$WATCHER ||= $guard;
696		976
697	=item @AnyEvent::post_detect	977	=item @AnyEvent::post_detect
698		978
699	If there are any code references in this array (you can C<push> to it	979	If there are any code references in this array (you can C<push> to it
700	before or after loading AnyEvent), then they will called directly after	980	before or after loading AnyEvent), then they will be called directly
701	the event loop has been chosen.	981	after the event loop has been chosen.
702		982
703	You should check C<$AnyEvent::MODEL> before adding to this array, though:	983	You should check C<$AnyEvent::MODEL> before adding to this array, though:
704	if it contains a true value then the event loop has already been detected,	984	if it is defined then the event loop has already been detected, and the
705	and the array will be ignored.	985	array will be ignored.
706		986
707	Best use C<AnyEvent::post_detect { BLOCK }> instead.	987	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		988	it, as it takes care of these details.
		989
		990	This variable is mainly useful for modules that can do something useful
		991	when AnyEvent is used and thus want to know when it is initialised, but do
		992	not need to even load it by default. This array provides the means to hook
		993	into AnyEvent passively, without loading it.
		994
		995	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		996	together, you could put this into Coro (this is the actual code used by
		997	Coro to accomplish this):
		998
		999	if (defined $AnyEvent::MODEL) {
		1000	# AnyEvent already initialised, so load Coro::AnyEvent
		1001	require Coro::AnyEvent;
		1002	} else {
		1003	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1004	# as soon as it is
		1005	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1006	}
708		1007
709	=back	1008	=back
710		1009
711	=head1 WHAT TO DO IN A MODULE	1010	=head1 WHAT TO DO IN A MODULE
712		1011
…		…
723	because it will stall the whole program, and the whole point of using	1022	because it will stall the whole program, and the whole point of using
724	events is to stay interactive.	1023	events is to stay interactive.
725		1024
726	It is fine, however, to call C<< ->recv >> when the user of your module	1025	It is fine, however, to call C<< ->recv >> when the user of your module
727	requests it (i.e. if you create a http request object ad have a method	1026	requests it (i.e. if you create a http request object ad have a method
728	called C<results> that returns the results, it should call C<< ->recv >>	1027	called C<results> that returns the results, it may call C<< ->recv >>
729	freely, as the user of your module knows what she is doing. always).	1028	freely, as the user of your module knows what she is doing. Always).
730		1029
731	=head1 WHAT TO DO IN THE MAIN PROGRAM	1030	=head1 WHAT TO DO IN THE MAIN PROGRAM
732		1031
733	There will always be a single main program - the only place that should	1032	There will always be a single main program - the only place that should
734	dictate which event model to use.	1033	dictate which event model to use.
735		1034
736	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1035	If the program is not event-based, it need not do anything special, even
737	do anything special (it does not need to be event-based) and let AnyEvent	1036	when it depends on a module that uses an AnyEvent. If the program itself
738	decide which implementation to chose if some module relies on it.	1037	uses AnyEvent, but does not care which event loop is used, all it needs
		1038	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1039	available loop implementation.
739		1040
740	If the main program relies on a specific event model - for example, in	1041	If the main program relies on a specific event model - for example, in
741	Gtk2 programs you have to rely on the Glib module - you should load the	1042	Gtk2 programs you have to rely on the Glib module - you should load the
742	event module before loading AnyEvent or any module that uses it: generally	1043	event module before loading AnyEvent or any module that uses it: generally
743	speaking, you should load it as early as possible. The reason is that	1044	speaking, you should load it as early as possible. The reason is that
744	modules might create watchers when they are loaded, and AnyEvent will	1045	modules might create watchers when they are loaded, and AnyEvent will
745	decide on the event model to use as soon as it creates watchers, and it	1046	decide on the event model to use as soon as it creates watchers, and it
746	might chose the wrong one unless you load the correct one yourself.	1047	might choose the wrong one unless you load the correct one yourself.
747		1048
748	You can chose to use a pure-perl implementation by loading the	1049	You can chose to use a pure-perl implementation by loading the
749	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1050	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
750	everywhere, but letting AnyEvent chose the model is generally better.	1051	everywhere, but letting AnyEvent chose the model is generally better.
751		1052
…		…
767		1068
768		1069
769	=head1 OTHER MODULES	1070	=head1 OTHER MODULES
770		1071
771	The following is a non-exhaustive list of additional modules that use	1072	The following is a non-exhaustive list of additional modules that use
772	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1073	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
773	in the same program. Some of the modules come with AnyEvent, some are	1074	modules and other event loops in the same program. Some of the modules
774	available via CPAN.	1075	come as part of AnyEvent, the others are available via CPAN.
775		1076
776	=over 4	1077	=over 4
777		1078
778	=item L<AnyEvent::Util>	1079	=item L<AnyEvent::Util>
779		1080
780	Contains various utility functions that replace often-used but blocking	1081	Contains various utility functions that replace often-used blocking
781	functions such as C<inet_aton> by event-/callback-based versions.	1082	functions such as C<inet_aton> with event/callback-based versions.
782		1083
783	=item L<AnyEvent::Socket>	1084	=item L<AnyEvent::Socket>
784		1085
785	Provides various utility functions for (internet protocol) sockets,	1086	Provides various utility functions for (internet protocol) sockets,
786	addresses and name resolution. Also functions to create non-blocking tcp	1087	addresses and name resolution. Also functions to create non-blocking tcp
…		…
788		1089
789	=item L<AnyEvent::Handle>	1090	=item L<AnyEvent::Handle>
790		1091
791	Provide read and write buffers, manages watchers for reads and writes,	1092	Provide read and write buffers, manages watchers for reads and writes,
792	supports raw and formatted I/O, I/O queued and fully transparent and	1093	supports raw and formatted I/O, I/O queued and fully transparent and
793	non-blocking SSL/TLS.	1094	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
794		1095
795	=item L<AnyEvent::DNS>	1096	=item L<AnyEvent::DNS>
796		1097
797	Provides rich asynchronous DNS resolver capabilities.	1098	Provides rich asynchronous DNS resolver capabilities.
798		1099
		1100	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1101
		1102	Implement event-based interfaces to the protocols of the same name (for
		1103	the curious, IGS is the International Go Server and FCP is the Freenet
		1104	Client Protocol).
		1105
		1106	=item L<AnyEvent::Handle::UDP>
		1107
		1108	Here be danger!
		1109
		1110	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1111	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1112	its use of a stream-based API with a protocol that isn't streamable, that
		1113	the only way to improve it is to delete it.
		1114
		1115	It features data corruption (but typically only under load) and general
		1116	confusion. On top, the author is not only clueless about UDP but also
		1117	fact-resistant - some gems of his understanding: "connect doesn't work
		1118	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1119	packets", "I don't need to implement proper error checking as UDP doesn't
		1120	support error checking" and so on - he doesn't even understand what's
		1121	wrong with his module when it is explained to him.
		1122
799	=item L<AnyEvent::HTTP>	1123	=item L<AnyEvent::DBI>
800		1124
801	A simple-to-use HTTP library that is capable of making a lot of concurrent	1125	Executes L<DBI> requests asynchronously in a proxy process for you,
802	HTTP requests.	1126	notifying you in an event-based way when the operation is finished.
		1127
		1128	=item L<AnyEvent::AIO>
		1129
		1130	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1131	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1132	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1133	file I/O, and much more.
803		1134
804	=item L<AnyEvent::HTTPD>	1135	=item L<AnyEvent::HTTPD>
805		1136
806	Provides a simple web application server framework.	1137	A simple embedded webserver.
807		1138
808	=item L<AnyEvent::FastPing>	1139	=item L<AnyEvent::FastPing>
809		1140
810	The fastest ping in the west.	1141	The fastest ping in the west.
811		1142
812	=item L<AnyEvent::DBI>
813
814	Executes L<DBI> requests asynchronously in a proxy process.
815
816	=item L<AnyEvent::AIO>
817
818	Truly asynchronous I/O, should be in the toolbox of every event
819	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
820	together.
821
822	=item L<AnyEvent::BDB>
823
824	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
825	L<BDB> and AnyEvent together.
826
827	=item L<AnyEvent::GPSD>
828
829	A non-blocking interface to gpsd, a daemon delivering GPS information.
830
831	=item L<AnyEvent::IGS>
832
833	A non-blocking interface to the Internet Go Server protocol (used by
834	L<App::IGS>).
835
836	=item L<AnyEvent::IRC>
837
838	AnyEvent based IRC client module family (replacing the older Net::IRC3).
839
840	=item L<Net::XMPP2>
841
842	AnyEvent based XMPP (Jabber protocol) module family.
843
844	=item L<Net::FCP>
845
846	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
847	of AnyEvent.
848
849	=item L<Event::ExecFlow>
850
851	High level API for event-based execution flow control.
852
853	=item L<Coro>	1143	=item L<Coro>
854		1144
855	Has special support for AnyEvent via L<Coro::AnyEvent>.	1145	Has special support for AnyEvent via L<Coro::AnyEvent>.
856		1146
857	=item L<IO::Lambda>
858
859	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
860
861	=back	1147	=back
862		1148
863	=cut	1149	=cut
864		1150
865	package AnyEvent;	1151	package AnyEvent;
866		1152
867	no warnings;	1153	# basically a tuned-down version of common::sense
868	use strict qw(vars subs);	1154	sub common_sense {
		1155	# from common:.sense 3.3
		1156	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf3\x0f\xc0\xf0\xfc\x33\x00";
		1157	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1158	$^H |= 0x00000600;
		1159	}
869		1160
		1161	BEGIN { AnyEvent::common_sense }
		1162
870	use Carp;	1163	use Carp ();
871		1164
872	our $VERSION = 4.341;	1165	our $VERSION = '5.29';
873	our $MODEL;	1166	our $MODEL;
874		1167
875	our $AUTOLOAD;	1168	our $AUTOLOAD;
876	our @ISA;	1169	our @ISA;
877		1170
878	our @REGISTRY;	1171	our @REGISTRY;
879		1172
880	our $WIN32;	1173	our $VERBOSE;
881		1174
882	BEGIN {	1175	BEGIN {
883	my $win32 = ! ! ($^O =~ /mswin32/i);	1176	require "AnyEvent/constants.pl";
884	eval "sub WIN32(){ $win32 }";
885	}
886		1177
		1178	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1179
		1180	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1181	if ${^TAINT};
		1182
887	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1183	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1184
		1185	}
		1186
		1187	our $MAX_SIGNAL_LATENCY = 10;
888		1188
889	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1189	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
890		1190
891	{	1191	{
892	my $idx;	1192	my $idx;
…		…
894	for reverse split /\s*,\s*/,	1194	for reverse split /\s*,\s*/,
895	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1195	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
896	}	1196	}
897		1197
898	my @models = (	1198	my @models = (
899	[EV:: => AnyEvent::Impl::EV::],	1199	[EV:: => AnyEvent::Impl::EV:: , 1],
900	[Event:: => AnyEvent::Impl::Event::],
901	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1200	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
902	# everything below here will not be autoprobed	1201	# everything below here will not (normally) be autoprobed
903	# as the pureperl backend should work everywhere	1202	# as the pureperl backend should work everywhere
904	# and is usually faster	1203	# and is usually faster
		1204	[Event:: => AnyEvent::Impl::Event::, 1],
		1205	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1206	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1207	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
905	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1208	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
906	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
907	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
908	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1209	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
909	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1210	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
910	[Wx:: => AnyEvent::Impl::POE::],	1211	[Wx:: => AnyEvent::Impl::POE::],
911	[Prima:: => AnyEvent::Impl::POE::],	1212	[Prima:: => AnyEvent::Impl::POE::],
		1213	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::],
912	);	1214	);
913		1215
914	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1216	our %method = map +($_ => 1),
		1217	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
915		1218
916	our @post_detect;	1219	our @post_detect;
917		1220
918	sub post_detect(&) {	1221	sub post_detect(&) {
919	my ($cb) = @_;	1222	my ($cb) = @_;
920		1223
921	if ($MODEL) {
922	$cb->();
923
924	1
925	} else {
926	push @post_detect, $cb;	1224	push @post_detect, $cb;
927		1225
928	defined wantarray	1226	defined wantarray
929	? bless \$cb, "AnyEvent::Util::PostDetect"	1227	? bless \$cb, "AnyEvent::Util::postdetect"
930	: ()	1228	: ()
		1229	}
		1230
		1231	sub AnyEvent::Util::postdetect::DESTROY {
		1232	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1233	}
		1234
		1235	sub detect() {
		1236	# free some memory
		1237	*detect = sub () { $MODEL };
		1238
		1239	local $!; # for good measure
		1240	local $SIG{__DIE__};
		1241
		1242	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1243	my $model = "AnyEvent::Impl::$1";
		1244	if (eval "require $model") {
		1245	$MODEL = $model;
		1246	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
		1247	} else {
		1248	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
		1249	}
931	}	1250	}
932	}
933		1251
934	sub AnyEvent::Util::PostDetect::DESTROY {	1252	# check for already loaded models
935	@post_detect = grep $_ != ${$_[0]}, @post_detect;
936	}
937
938	sub detect() {
939	unless ($MODEL) {	1253	unless ($MODEL) {
940	no strict 'refs';	1254	for (@REGISTRY, @models) {
941	local $SIG{__DIE__};	1255	my ($package, $model) = @$_;
942		1256	if (${"$package\::VERSION"} > 0) {
943	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
944	my $model = "AnyEvent::Impl::$1";
945	if (eval "require $model") {	1257	if (eval "require $model") {
946	$MODEL = $model;	1258	$MODEL = $model;
947	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1259	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
948	} else {	1260	last;
949	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1261	}
950	}	1262	}
951	}	1263	}
952		1264
953	# check for already loaded models
954	unless ($MODEL) {	1265	unless ($MODEL) {
		1266	# try to autoload a model
955	for (@REGISTRY, @models) {	1267	for (@REGISTRY, @models) {
956	my ($package, $model) = @$_;	1268	my ($package, $model, $autoload) = @$_;
		1269	if (
		1270	$autoload
		1271	and eval "require $package"
957	if (${"$package\::VERSION"} > 0) {	1272	and ${"$package\::VERSION"} > 0
958	if (eval "require $model") {	1273	and eval "require $model"
		1274	) {
959	$MODEL = $model;	1275	$MODEL = $model;
960	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1276	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
961	last;	1277	last;
962	}
963	}	1278	}
964	}	1279	}
965		1280
966	unless ($MODEL) {
967	# try to load a model
968
969	for (@REGISTRY, @models) {
970	my ($package, $model) = @$_;
971	if (eval "require $package"
972	and ${"$package\::VERSION"} > 0
973	and eval "require $model") {
974	$MODEL = $model;
975	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
976	last;
977	}
978	}
979
980	$MODEL	1281	$MODEL
981	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1282	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
982	}
983	}	1283	}
984
985	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
986
987	unshift @ISA, $MODEL;
988
989	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
990
991	(shift @post_detect)->() while @post_detect;
992	}	1284	}
		1285
		1286	@models = (); # free probe data
		1287
		1288	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1289	unshift @ISA, $MODEL;
		1290
		1291	# now nuke some methods that are overridden by the backend.
		1292	# SUPER is not allowed.
		1293	for (qw(time signal child idle)) {
		1294	undef &{"AnyEvent::Base::$_"}
		1295	if defined &{"$MODEL\::$_"};
		1296	}
		1297
		1298	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1299	eval { require AnyEvent::Strict };
		1300	warn "AnyEvent: cannot load AnyEvent::Strict: $@"
		1301	if $@ && $VERBOSE;
		1302	}
		1303
		1304	(shift @post_detect)->() while @post_detect;
		1305
		1306	*post_detect = sub(&) {
		1307	shift->();
		1308
		1309	undef
		1310	};
993		1311
994	$MODEL	1312	$MODEL
995	}	1313	}
996		1314
997	sub AUTOLOAD {	1315	sub AUTOLOAD {
998	(my $func = $AUTOLOAD) =~ s/.*://;	1316	(my $func = $AUTOLOAD) =~ s/.*://;
999		1317
1000	$method{$func}	1318	$method{$func}
1001	or croak "$func: not a valid method for AnyEvent objects";	1319	or Carp::croak "$func: not a valid AnyEvent class method";
1002		1320
1003	detect unless $MODEL;	1321	detect;
1004		1322
1005	my $class = shift;	1323	my $class = shift;
1006	$class->$func (@_);	1324	$class->$func (@_);
1007	}	1325	}
1008		1326
1009	# utility function to dup a filehandle. this is used by many backends	1327	# utility function to dup a filehandle. this is used by many backends
1010	# to support binding more than one watcher per filehandle (they usually	1328	# to support binding more than one watcher per filehandle (they usually
1011	# allow only one watcher per fd, so we dup it to get a different one).	1329	# allow only one watcher per fd, so we dup it to get a different one).
1012	sub _dupfh($$$$) {	1330	sub _dupfh($$;$$) {
1013	my ($poll, $fh, $r, $w) = @_;	1331	my ($poll, $fh, $r, $w) = @_;
1014		1332
1015	# cygwin requires the fh mode to be matching, unix doesn't	1333	# cygwin requires the fh mode to be matching, unix doesn't
1016	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1334	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1017	: $poll eq "w" ? ($w, ">")
1018	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1019		1335
1020	open my $fh2, "$mode&" . fileno $fh	1336	open my $fh2, $mode, $fh
1021	or die "cannot dup() filehandle: $!";	1337	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1022		1338
1023	# we assume CLOEXEC is already set by perl in all important cases	1339	# we assume CLOEXEC is already set by perl in all important cases
1024		1340
1025	($fh2, $rw)	1341	($fh2, $rw)
1026	}	1342	}
1027		1343
		1344	=head1 SIMPLIFIED AE API
		1345
		1346	Starting with version 5.0, AnyEvent officially supports a second, much
		1347	simpler, API that is designed to reduce the calling, typing and memory
		1348	overhead by using function call syntax and a fixed number of parameters.
		1349
		1350	See the L<AE> manpage for details.
		1351
		1352	=cut
		1353
		1354	package AE;
		1355
		1356	our $VERSION = $AnyEvent::VERSION;
		1357
		1358	# fall back to the main API by default - backends and AnyEvent::Base
		1359	# implementations can overwrite these.
		1360
		1361	sub io($$$) {
		1362	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1363	}
		1364
		1365	sub timer($$$) {
		1366	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1367	}
		1368
		1369	sub signal($$) {
		1370	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1371	}
		1372
		1373	sub child($$) {
		1374	AnyEvent->child (pid => $_[0], cb => $_[1])
		1375	}
		1376
		1377	sub idle($) {
		1378	AnyEvent->idle (cb => $_[0])
		1379	}
		1380
		1381	sub cv(;&) {
		1382	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1383	}
		1384
		1385	sub now() {
		1386	AnyEvent->now
		1387	}
		1388
		1389	sub now_update() {
		1390	AnyEvent->now_update
		1391	}
		1392
		1393	sub time() {
		1394	AnyEvent->time
		1395	}
		1396
1028	package AnyEvent::Base;	1397	package AnyEvent::Base;
1029		1398
1030	# default implementation for now and time	1399	# default implementations for many methods
1031		1400
1032	BEGIN {	1401	sub time {
		1402	eval q{ # poor man's autoloading {}
		1403	# probe for availability of Time::HiRes
1033	if (eval "use Time::HiRes (); time (); 1") {	1404	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1405	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1034	*_time = \&Time::HiRes::time;	1406	*AE::time = \&Time::HiRes::time;
1035	# if (eval "use POSIX (); (POSIX::times())...	1407	# if (eval "use POSIX (); (POSIX::times())...
1036	} else {	1408	} else {
		1409	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1037	*_time = sub { time }; # epic fail	1410	*AE::time = sub (){ time }; # epic fail
		1411	}
		1412
		1413	*time = sub { AE::time }; # different prototypes
		1414	};
		1415	die if $@;
		1416
		1417	&time
		1418	}
		1419
		1420	*now = \&time;
		1421
		1422	sub now_update { }
		1423
		1424	# default implementation for ->condvar
		1425
		1426	sub condvar {
		1427	eval q{ # poor man's autoloading {}
		1428	*condvar = sub {
		1429	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1430	};
		1431
		1432	*AE::cv = sub (;&) {
		1433	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1434	};
		1435	};
		1436	die if $@;
		1437
		1438	&condvar
		1439	}
		1440
		1441	# default implementation for ->signal
		1442
		1443	our $HAVE_ASYNC_INTERRUPT;
		1444
		1445	sub _have_async_interrupt() {
		1446	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1447	&& eval "use Async::Interrupt 1.02 (); 1")
		1448	unless defined $HAVE_ASYNC_INTERRUPT;
		1449
		1450	$HAVE_ASYNC_INTERRUPT
		1451	}
		1452
		1453	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1454	our (%SIG_ASY, %SIG_ASY_W);
		1455	our ($SIG_COUNT, $SIG_TW);
		1456
		1457	# install a dummy wakeup watcher to reduce signal catching latency
		1458	# used by Impls
		1459	sub _sig_add() {
		1460	unless ($SIG_COUNT++) {
		1461	# try to align timer on a full-second boundary, if possible
		1462	my $NOW = AE::now;
		1463
		1464	$SIG_TW = AE::timer
		1465	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1466	$MAX_SIGNAL_LATENCY,
		1467	sub { } # just for the PERL_ASYNC_CHECK
		1468	;
1038	}	1469	}
1039	}	1470	}
1040		1471
1041	sub time { _time }	1472	sub _sig_del {
1042	sub now { _time }	1473	undef $SIG_TW
1043		1474	unless --$SIG_COUNT;
1044	# default implementation for ->condvar
1045
1046	sub condvar {
1047	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
1048	}	1475	}
1049		1476
1050	# default implementation for ->signal	1477	our $_sig_name_init; $_sig_name_init = sub {
		1478	eval q{ # poor man's autoloading {}
		1479	undef $_sig_name_init;
1051		1480
1052	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1481	if (_have_async_interrupt) {
		1482	*sig2num = \&Async::Interrupt::sig2num;
		1483	*sig2name = \&Async::Interrupt::sig2name;
		1484	} else {
		1485	require Config;
1053		1486
1054	sub _signal_exec {	1487	my %signame2num;
1055	while (%SIG_EV) {	1488	@signame2num{ split ' ', $Config::Config{sig_name} }
1056	sysread $SIGPIPE_R, my $dummy, 4;	1489	= split ' ', $Config::Config{sig_num};
1057	for (keys %SIG_EV) {	1490
1058	delete $SIG_EV{$_};	1491	my @signum2name;
1059	$_->() for values %{ $SIG_CB{$_} || {} };	1492	@signum2name[values %signame2num] = keys %signame2num;
		1493
		1494	*sig2num = sub($) {
		1495	$_[0] > 0 ? shift : $signame2num{+shift}
		1496	};
		1497	*sig2name = sub ($) {
		1498	$_[0] > 0 ? $signum2name[+shift] : shift
		1499	};
1060	}	1500	}
1061	}	1501	};
1062	}	1502	die if $@;
		1503	};
		1504
		1505	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1506	sub sig2name($) { &$_sig_name_init; &sig2name }
1063		1507
1064	sub signal {	1508	sub signal {
1065	my (undef, %arg) = @_;	1509	eval q{ # poor man's autoloading {}
		1510	# probe for availability of Async::Interrupt
		1511	if (_have_async_interrupt) {
		1512	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1066		1513
1067	unless ($SIGPIPE_R) {	1514	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1068	if (AnyEvent::WIN32) {	1515	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1069	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();	1516
1070	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1071	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1072	} else {	1517	} else {
		1518	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1519
		1520	if (AnyEvent::WIN32) {
		1521	require AnyEvent::Util;
		1522
		1523	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1524	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1525	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1526	} else {
1073	pipe $SIGPIPE_R, $SIGPIPE_W;	1527	pipe $SIGPIPE_R, $SIGPIPE_W;
1074	require Fcntl;
1075	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1528	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1076	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1529	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1530
		1531	# not strictly required, as $^F is normally 2, but let's make sure...
		1532	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1533	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1534	}
		1535
		1536	$SIGPIPE_R
		1537	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1538
		1539	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1077	}	1540	}
1078		1541
1079	$SIGPIPE_R	1542	*signal = $HAVE_ASYNC_INTERRUPT
1080	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1543	? sub {
		1544	my (undef, %arg) = @_;
1081		1545
1082	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1546	# async::interrupt
1083	}
1084
1085	my $signal = uc $arg{signal}	1547	my $signal = sig2num $arg{signal};
1086	or Carp::croak "required option 'signal' is missing";
1087
1088	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1548	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1549
		1550	$SIG_ASY{$signal} ||= new Async::Interrupt
		1551	cb => sub { undef $SIG_EV{$signal} },
		1552	signal => $signal,
		1553	pipe => [$SIGPIPE_R->filenos],
		1554	pipe_autodrain => 0,
		1555	;
		1556
		1557	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1558	}
		1559	: sub {
		1560	my (undef, %arg) = @_;
		1561
		1562	# pure perl
		1563	my $signal = sig2name $arg{signal};
		1564	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1565
1089	$SIG{$signal} ||= sub {	1566	$SIG{$signal} ||= sub {
		1567	local $!;
1090	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1568	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1091	undef $SIG_EV{$signal};	1569	undef $SIG_EV{$signal};
		1570	};
		1571
		1572	# can't do signal processing without introducing races in pure perl,
		1573	# so limit the signal latency.
		1574	_sig_add;
		1575
		1576	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1577	}
		1578	;
		1579
		1580	*AnyEvent::Base::signal::DESTROY = sub {
		1581	my ($signal, $cb) = @{$_[0]};
		1582
		1583	_sig_del;
		1584
		1585	delete $SIG_CB{$signal}{$cb};
		1586
		1587	$HAVE_ASYNC_INTERRUPT
		1588	? delete $SIG_ASY{$signal}
		1589	: # delete doesn't work with older perls - they then
		1590	# print weird messages, or just unconditionally exit
		1591	# instead of getting the default action.
		1592	undef $SIG{$signal}
		1593	unless keys %{ $SIG_CB{$signal} };
		1594	};
		1595
		1596	*_signal_exec = sub {
		1597	$HAVE_ASYNC_INTERRUPT
		1598	? $SIGPIPE_R->drain
		1599	: sysread $SIGPIPE_R, (my $dummy), 9;
		1600
		1601	while (%SIG_EV) {
		1602	for (keys %SIG_EV) {
		1603	delete $SIG_EV{$_};
		1604	$_->() for values %{ $SIG_CB{$_} || {} };
		1605	}
		1606	}
		1607	};
1092	};	1608	};
		1609	die if $@;
1093		1610
1094	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1611	&signal
1095	}
1096
1097	sub AnyEvent::Base::Signal::DESTROY {
1098	my ($signal, $cb) = @{$_[0]};
1099
1100	delete $SIG_CB{$signal}{$cb};
1101
1102	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1103	}	1612	}
1104		1613
1105	# default implementation for ->child	1614	# default implementation for ->child
1106		1615
1107	our %PID_CB;	1616	our %PID_CB;
1108	our $CHLD_W;	1617	our $CHLD_W;
1109	our $CHLD_DELAY_W;	1618	our $CHLD_DELAY_W;
1110	our $PID_IDLE;
1111	our $WNOHANG;
1112		1619
1113	sub _child_wait {	1620	# used by many Impl's
1114	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1621	sub _emit_childstatus($$) {
		1622	my (undef, $rpid, $rstatus) = @_;
		1623
		1624	$_->($rpid, $rstatus)
1115	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1625	for values %{ $PID_CB{$rpid} || {} },
1116	(values %{ $PID_CB{0} || {} });	1626	values %{ $PID_CB{0} || {} };
1117	}
1118
1119	undef $PID_IDLE;
1120	}
1121
1122	sub _sigchld {
1123	# make sure we deliver these changes "synchronous" with the event loop.
1124	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1125	undef $CHLD_DELAY_W;
1126	&_child_wait;
1127	});
1128	}	1627	}
1129		1628
1130	sub child {	1629	sub child {
		1630	eval q{ # poor man's autoloading {}
		1631	*_sigchld = sub {
		1632	my $pid;
		1633
		1634	AnyEvent->_emit_childstatus ($pid, $?)
		1635	while ($pid = waitpid -1, WNOHANG) > 0;
		1636	};
		1637
		1638	*child = sub {
1131	my (undef, %arg) = @_;	1639	my (undef, %arg) = @_;
1132		1640
1133	defined (my $pid = $arg{pid} + 0)	1641	defined (my $pid = $arg{pid} + 0)
1134	or Carp::croak "required option 'pid' is missing";	1642	or Carp::croak "required option 'pid' is missing";
1135		1643
1136	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1644	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1137		1645
1138	unless ($WNOHANG) {
1139	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1140	}
1141
1142	unless ($CHLD_W) {	1646	unless ($CHLD_W) {
1143	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1647	$CHLD_W = AE::signal CHLD => \&_sigchld;
1144	# child could be a zombie already, so make at least one round	1648	# child could be a zombie already, so make at least one round
1145	&_sigchld;	1649	&_sigchld;
1146	}	1650	}
1147		1651
1148	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1652	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1149	}	1653	};
1150		1654
1151	sub AnyEvent::Base::Child::DESTROY {	1655	*AnyEvent::Base::child::DESTROY = sub {
1152	my ($pid, $cb) = @{$_[0]};	1656	my ($pid, $cb) = @{$_[0]};
1153		1657
1154	delete $PID_CB{$pid}{$cb};	1658	delete $PID_CB{$pid}{$cb};
1155	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1659	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1156		1660
1157	undef $CHLD_W unless keys %PID_CB;	1661	undef $CHLD_W unless keys %PID_CB;
		1662	};
		1663	};
		1664	die if $@;
		1665
		1666	&child
		1667	}
		1668
		1669	# idle emulation is done by simply using a timer, regardless
		1670	# of whether the process is idle or not, and not letting
		1671	# the callback use more than 50% of the time.
		1672	sub idle {
		1673	eval q{ # poor man's autoloading {}
		1674	*idle = sub {
		1675	my (undef, %arg) = @_;
		1676
		1677	my ($cb, $w, $rcb) = $arg{cb};
		1678
		1679	$rcb = sub {
		1680	if ($cb) {
		1681	$w = _time;
		1682	&$cb;
		1683	$w = _time - $w;
		1684
		1685	# never use more then 50% of the time for the idle watcher,
		1686	# within some limits
		1687	$w = 0.0001 if $w < 0.0001;
		1688	$w = 5 if $w > 5;
		1689
		1690	$w = AE::timer $w, 0, $rcb;
		1691	} else {
		1692	# clean up...
		1693	undef $w;
		1694	undef $rcb;
		1695	}
		1696	};
		1697
		1698	$w = AE::timer 0.05, 0, $rcb;
		1699
		1700	bless \\$cb, "AnyEvent::Base::idle"
		1701	};
		1702
		1703	*AnyEvent::Base::idle::DESTROY = sub {
		1704	undef $${$_[0]};
		1705	};
		1706	};
		1707	die if $@;
		1708
		1709	&idle
1158	}	1710	}
1159		1711
1160	package AnyEvent::CondVar;	1712	package AnyEvent::CondVar;
1161		1713
1162	our @ISA = AnyEvent::CondVar::Base::;	1714	our @ISA = AnyEvent::CondVar::Base::;
1163		1715
		1716	# only to be used for subclassing
		1717	sub new {
		1718	my $class = shift;
		1719	bless AnyEvent->condvar (@_), $class
		1720	}
		1721
1164	package AnyEvent::CondVar::Base;	1722	package AnyEvent::CondVar::Base;
1165		1723
1166	use overload	1724	#use overload
1167	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1725	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1168	fallback => 1;	1726	# fallback => 1;
		1727
		1728	# save 300+ kilobytes by dirtily hardcoding overloading
		1729	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1730	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1731	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1732	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1733
		1734	our $WAITING;
1169		1735
1170	sub _send {	1736	sub _send {
1171	# nop	1737	# nop
1172	}	1738	}
1173		1739
…		…
1186	sub ready {	1752	sub ready {
1187	$_[0]{_ae_sent}	1753	$_[0]{_ae_sent}
1188	}	1754	}
1189		1755
1190	sub _wait {	1756	sub _wait {
		1757	$WAITING
		1758	and !$_[0]{_ae_sent}
		1759	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1760
		1761	local $WAITING = 1;
1191	AnyEvent->one_event while !$_[0]{_ae_sent};	1762	AnyEvent->one_event while !$_[0]{_ae_sent};
1192	}	1763	}
1193		1764
1194	sub recv {	1765	sub recv {
1195	$_[0]->_wait;	1766	$_[0]->_wait;
…		…
1197	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1768	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1198	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1769	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1199	}	1770	}
1200		1771
1201	sub cb {	1772	sub cb {
1202	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1773	my $cv = shift;
		1774
		1775	@_
		1776	and $cv->{_ae_cb} = shift
		1777	and $cv->{_ae_sent}
		1778	and (delete $cv->{_ae_cb})->($cv);
		1779
1203	$_[0]{_ae_cb}	1780	$cv->{_ae_cb}
1204	}	1781	}
1205		1782
1206	sub begin {	1783	sub begin {
1207	++$_[0]{_ae_counter};	1784	++$_[0]{_ae_counter};
1208	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1785	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1236	so on.	1813	so on.
1237		1814
1238	=head1 ENVIRONMENT VARIABLES	1815	=head1 ENVIRONMENT VARIABLES
1239		1816
1240	The following environment variables are used by this module or its	1817	The following environment variables are used by this module or its
1241	submodules:	1818	submodules.
		1819
		1820	Note that AnyEvent will remove I<all> environment variables starting with
		1821	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1822	enabled.
1242		1823
1243	=over 4	1824	=over 4
1244		1825
1245	=item C<PERL_ANYEVENT_VERBOSE>	1826	=item C<PERL_ANYEVENT_VERBOSE>
1246		1827
…		…
1253	C<PERL_ANYEVENT_MODEL>.	1834	C<PERL_ANYEVENT_MODEL>.
1254		1835
1255	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1836	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1256	model it chooses.	1837	model it chooses.
1257		1838
		1839	When set to C<8> or higher, then AnyEvent will report extra information on
		1840	which optional modules it loads and how it implements certain features.
		1841
1258	=item C<PERL_ANYEVENT_STRICT>	1842	=item C<PERL_ANYEVENT_STRICT>
1259		1843
1260	AnyEvent does not do much argument checking by default, as thorough	1844	AnyEvent does not do much argument checking by default, as thorough
1261	argument checking is very costly. Setting this variable to a true value	1845	argument checking is very costly. Setting this variable to a true value
1262	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1846	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1263	check the arguments passed to most method calls. If it finds any problems	1847	check the arguments passed to most method calls. If it finds any problems,
1264	it will croak.	1848	it will croak.
1265		1849
1266	In other words, enables "strict" mode.	1850	In other words, enables "strict" mode.
1267		1851
1268	Unlike C<use strict>, it is definitely recommended ot keep it off in	1852	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1269	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1853	>>, it is definitely recommended to keep it off in production. Keeping
1270	developing programs can be very useful, however.	1854	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1855	can be very useful, however.
1271		1856
1272	=item C<PERL_ANYEVENT_MODEL>	1857	=item C<PERL_ANYEVENT_MODEL>
1273		1858
1274	This can be used to specify the event model to be used by AnyEvent, before	1859	This can be used to specify the event model to be used by AnyEvent, before
1275	auto detection and -probing kicks in. It must be a string consisting	1860	auto detection and -probing kicks in. It must be a string consisting
…		…
1318		1903
1319	=item C<PERL_ANYEVENT_MAX_FORKS>	1904	=item C<PERL_ANYEVENT_MAX_FORKS>
1320		1905
1321	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1906	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1322	will create in parallel.	1907	will create in parallel.
		1908
		1909	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1910
		1911	The default value for the C<max_outstanding> parameter for the default DNS
		1912	resolver - this is the maximum number of parallel DNS requests that are
		1913	sent to the DNS server.
		1914
		1915	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1916
		1917	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1918	configuration) in the default resolver. When set to the empty string, no
		1919	default config will be used.
		1920
		1921	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1922
		1923	When neither C<ca_file> nor C<ca_path> was specified during
		1924	L<AnyEvent::TLS> context creation, and either of these environment
		1925	variables exist, they will be used to specify CA certificate locations
		1926	instead of a system-dependent default.
		1927
		1928	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1929
		1930	When these are set to C<1>, then the respective modules are not
		1931	loaded. Mostly good for testing AnyEvent itself.
1323		1932
1324	=back	1933	=back
1325		1934
1326	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1935	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1327		1936
…		…
1385	warn "read: $input\n"; # output what has been read	1994	warn "read: $input\n"; # output what has been read
1386	$cv->send if $input =~ /^q/i; # quit program if /^q/i	1995	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1387	},	1996	},
1388	);	1997	);
1389		1998
1390	my $time_watcher; # can only be used once
1391
1392	sub new_timer {
1393	$timer = AnyEvent->timer (after => 1, cb => sub {	1999	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1394	warn "timeout\n"; # print 'timeout' about every second	2000	warn "timeout\n"; # print 'timeout' at most every second
1395	&new_timer; # and restart the time
1396	});	2001	});
1397	}
1398
1399	new_timer; # create first timer
1400		2002
1401	$cv->recv; # wait until user enters /^q/i	2003	$cv->recv; # wait until user enters /^q/i
1402		2004
1403	=head1 REAL-WORLD EXAMPLE	2005	=head1 REAL-WORLD EXAMPLE
1404		2006
…		…
1477		2079
1478	The actual code goes further and collects all errors (C<die>s, exceptions)	2080	The actual code goes further and collects all errors (C<die>s, exceptions)
1479	that occurred during request processing. The C<result> method detects	2081	that occurred during request processing. The C<result> method detects
1480	whether an exception as thrown (it is stored inside the $txn object)	2082	whether an exception as thrown (it is stored inside the $txn object)
1481	and just throws the exception, which means connection errors and other	2083	and just throws the exception, which means connection errors and other
1482	problems get reported tot he code that tries to use the result, not in a	2084	problems get reported to the code that tries to use the result, not in a
1483	random callback.	2085	random callback.
1484		2086
1485	All of this enables the following usage styles:	2087	All of this enables the following usage styles:
1486		2088
1487	1. Blocking:	2089	1. Blocking:
…		…
1535	through AnyEvent. The benchmark creates a lot of timers (with a zero	2137	through AnyEvent. The benchmark creates a lot of timers (with a zero
1536	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2138	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1537	which it is), lets them fire exactly once and destroys them again.	2139	which it is), lets them fire exactly once and destroys them again.
1538		2140
1539	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2141	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1540	distribution.	2142	distribution. It uses the L<AE> interface, which makes a real difference
		2143	for the EV and Perl backends only.
1541		2144
1542	=head3 Explanation of the columns	2145	=head3 Explanation of the columns
1543		2146
1544	I<watcher> is the number of event watchers created/destroyed. Since	2147	I<watcher> is the number of event watchers created/destroyed. Since
1545	different event models feature vastly different performances, each event	2148	different event models feature vastly different performances, each event
…		…
1566	watcher.	2169	watcher.
1567		2170
1568	=head3 Results	2171	=head3 Results
1569		2172
1570	name watchers bytes create invoke destroy comment	2173	name watchers bytes create invoke destroy comment
1571	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2174	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1572	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2175	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1573	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2176	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1574	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2177	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1575	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2178	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1576	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2179	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2180	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2181	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1577	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2182	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1578	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2183	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1579	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2184	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1580	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2185	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1581		2186
1582	=head3 Discussion	2187	=head3 Discussion
1583		2188
1584	The benchmark does I<not> measure scalability of the event loop very	2189	The benchmark does I<not> measure scalability of the event loop very
1585	well. For example, a select-based event loop (such as the pure perl one)	2190	well. For example, a select-based event loop (such as the pure perl one)
…		…
1597	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2202	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1598	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2203	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1599	cycles with POE.	2204	cycles with POE.
1600		2205
1601	C<EV> is the sole leader regarding speed and memory use, which are both	2206	C<EV> is the sole leader regarding speed and memory use, which are both
1602	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2207	maximal/minimal, respectively. When using the L<AE> API there is zero
		2208	overhead (when going through the AnyEvent API create is about 5-6 times
		2209	slower, with other times being equal, so still uses far less memory than
1603	far less memory than any other event loop and is still faster than Event	2210	any other event loop and is still faster than Event natively).
1604	natively.
1605		2211
1606	The pure perl implementation is hit in a few sweet spots (both the	2212	The pure perl implementation is hit in a few sweet spots (both the
1607	constant timeout and the use of a single fd hit optimisations in the perl	2213	constant timeout and the use of a single fd hit optimisations in the perl
1608	interpreter and the backend itself). Nevertheless this shows that it	2214	interpreter and the backend itself). Nevertheless this shows that it
1609	adds very little overhead in itself. Like any select-based backend its	2215	adds very little overhead in itself. Like any select-based backend its
1610	performance becomes really bad with lots of file descriptors (and few of	2216	performance becomes really bad with lots of file descriptors (and few of
1611	them active), of course, but this was not subject of this benchmark.	2217	them active), of course, but this was not subject of this benchmark.
1612		2218
1613	The C<Event> module has a relatively high setup and callback invocation	2219	The C<Event> module has a relatively high setup and callback invocation
1614	cost, but overall scores in on the third place.	2220	cost, but overall scores in on the third place.
		2221
		2222	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2223	when using its pure perl backend.
1615		2224
1616	C<Glib>'s memory usage is quite a bit higher, but it features a	2225	C<Glib>'s memory usage is quite a bit higher, but it features a
1617	faster callback invocation and overall ends up in the same class as	2226	faster callback invocation and overall ends up in the same class as
1618	C<Event>. However, Glib scales extremely badly, doubling the number of	2227	C<Event>. However, Glib scales extremely badly, doubling the number of
1619	watchers increases the processing time by more than a factor of four,	2228	watchers increases the processing time by more than a factor of four,
…		…
1680	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2289	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1681	(1%) are active. This mirrors the activity of large servers with many	2290	(1%) are active. This mirrors the activity of large servers with many
1682	connections, most of which are idle at any one point in time.	2291	connections, most of which are idle at any one point in time.
1683		2292
1684	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2293	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1685	distribution.	2294	distribution. It uses the L<AE> interface, which makes a real difference
		2295	for the EV and Perl backends only.
1686		2296
1687	=head3 Explanation of the columns	2297	=head3 Explanation of the columns
1688		2298
1689	I<sockets> is the number of sockets, and twice the number of "servers" (as	2299	I<sockets> is the number of sockets, and twice the number of "servers" (as
1690	each server has a read and write socket end).	2300	each server has a read and write socket end).
…		…
1697	it to another server. This includes deleting the old timeout and creating	2307	it to another server. This includes deleting the old timeout and creating
1698	a new one that moves the timeout into the future.	2308	a new one that moves the timeout into the future.
1699		2309
1700	=head3 Results	2310	=head3 Results
1701		2311
1702	name sockets create request	2312	name sockets create request
1703	EV 20000 69.01 11.16	2313	EV 20000 62.66 7.99
1704	Perl 20000 73.32 35.87	2314	Perl 20000 68.32 32.64
1705	Event 20000 212.62 257.32	2315	IOAsync 20000 174.06 101.15 epoll
1706	Glib 20000 651.16 1896.30	2316	IOAsync 20000 174.67 610.84 poll
		2317	Event 20000 202.69 242.91
		2318	Glib 20000 557.01 1689.52
1707	POE 20000 349.67 12317.24 uses POE::Loop::Event	2319	POE 20000 341.54 12086.32 uses POE::Loop::Event
1708		2320
1709	=head3 Discussion	2321	=head3 Discussion
1710		2322
1711	This benchmark I<does> measure scalability and overall performance of the	2323	This benchmark I<does> measure scalability and overall performance of the
1712	particular event loop.	2324	particular event loop.
…		…
1714	EV is again fastest. Since it is using epoll on my system, the setup time	2326	EV is again fastest. Since it is using epoll on my system, the setup time
1715	is relatively high, though.	2327	is relatively high, though.
1716		2328
1717	Perl surprisingly comes second. It is much faster than the C-based event	2329	Perl surprisingly comes second. It is much faster than the C-based event
1718	loops Event and Glib.	2330	loops Event and Glib.
		2331
		2332	IO::Async performs very well when using its epoll backend, and still quite
		2333	good compared to Glib when using its pure perl backend.
1719		2334
1720	Event suffers from high setup time as well (look at its code and you will	2335	Event suffers from high setup time as well (look at its code and you will
1721	understand why). Callback invocation also has a high overhead compared to	2336	understand why). Callback invocation also has a high overhead compared to
1722	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2337	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1723	uses select or poll in basically all documented configurations.	2338	uses select or poll in basically all documented configurations.
…		…
1786	=item * C-based event loops perform very well with small number of	2401	=item * C-based event loops perform very well with small number of
1787	watchers, as the management overhead dominates.	2402	watchers, as the management overhead dominates.
1788		2403
1789	=back	2404	=back
1790		2405
		2406	=head2 THE IO::Lambda BENCHMARK
		2407
		2408	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2409	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2410	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2411	shouldn't come as a surprise to anybody). As such, the benchmark is
		2412	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2413	very optimal. But how would AnyEvent compare when used without the extra
		2414	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2415
		2416	The benchmark itself creates an echo-server, and then, for 500 times,
		2417	connects to the echo server, sends a line, waits for the reply, and then
		2418	creates the next connection. This is a rather bad benchmark, as it doesn't
		2419	test the efficiency of the framework or much non-blocking I/O, but it is a
		2420	benchmark nevertheless.
		2421
		2422	name runtime
		2423	Lambda/select 0.330 sec
		2424	+ optimized 0.122 sec
		2425	Lambda/AnyEvent 0.327 sec
		2426	+ optimized 0.138 sec
		2427	Raw sockets/select 0.077 sec
		2428	POE/select, components 0.662 sec
		2429	POE/select, raw sockets 0.226 sec
		2430	POE/select, optimized 0.404 sec
		2431
		2432	AnyEvent/select/nb 0.085 sec
		2433	AnyEvent/EV/nb 0.068 sec
		2434	+state machine 0.134 sec
		2435
		2436	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2437	benchmarks actually make blocking connects and use 100% blocking I/O,
		2438	defeating the purpose of an event-based solution. All of the newly
		2439	written AnyEvent benchmarks use 100% non-blocking connects (using
		2440	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2441	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2442	generally require a lot more bookkeeping and event handling than blocking
		2443	connects (which involve a single syscall only).
		2444
		2445	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2446	offers similar expressive power as POE and IO::Lambda, using conventional
		2447	Perl syntax. This means that both the echo server and the client are 100%
		2448	non-blocking, further placing it at a disadvantage.
		2449
		2450	As you can see, the AnyEvent + EV combination even beats the
		2451	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2452	backend easily beats IO::Lambda and POE.
		2453
		2454	And even the 100% non-blocking version written using the high-level (and
		2455	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2456	higher level ("unoptimised") abstractions by a large margin, even though
		2457	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2458
		2459	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2460	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2461	part of the IO::Lambda distribution and were used without any changes.
		2462
1791		2463
1792	=head1 SIGNALS	2464	=head1 SIGNALS
1793		2465
1794	AnyEvent currently installs handlers for these signals:	2466	AnyEvent currently installs handlers for these signals:
1795		2467
…		…
1798	=item SIGCHLD	2470	=item SIGCHLD
1799		2471
1800	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2472	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1801	emulation for event loops that do not support them natively. Also, some	2473	emulation for event loops that do not support them natively. Also, some
1802	event loops install a similar handler.	2474	event loops install a similar handler.
		2475
		2476	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2477	AnyEvent will reset it to default, to avoid losing child exit statuses.
1803		2478
1804	=item SIGPIPE	2479	=item SIGPIPE
1805		2480
1806	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2481	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1807	when AnyEvent gets loaded.	2482	when AnyEvent gets loaded.
…		…
1819		2494
1820	=back	2495	=back
1821		2496
1822	=cut	2497	=cut
1823		2498
		2499	undef $SIG{CHLD}
		2500	if $SIG{CHLD} eq 'IGNORE';
		2501
1824	$SIG{PIPE} = sub { }	2502	$SIG{PIPE} = sub { }
1825	unless defined $SIG{PIPE};	2503	unless defined $SIG{PIPE};
1826		2504
		2505	=head1 RECOMMENDED/OPTIONAL MODULES
		2506
		2507	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2508	its built-in modules) are required to use it.
		2509
		2510	That does not mean that AnyEvent won't take advantage of some additional
		2511	modules if they are installed.
		2512
		2513	This section explains which additional modules will be used, and how they
		2514	affect AnyEvent's operation.
		2515
		2516	=over 4
		2517
		2518	=item L<Async::Interrupt>
		2519
		2520	This slightly arcane module is used to implement fast signal handling: To
		2521	my knowledge, there is no way to do completely race-free and quick
		2522	signal handling in pure perl. To ensure that signals still get
		2523	delivered, AnyEvent will start an interval timer to wake up perl (and
		2524	catch the signals) with some delay (default is 10 seconds, look for
		2525	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2526
		2527	If this module is available, then it will be used to implement signal
		2528	catching, which means that signals will not be delayed, and the event loop
		2529	will not be interrupted regularly, which is more efficient (and good for
		2530	battery life on laptops).
		2531
		2532	This affects not just the pure-perl event loop, but also other event loops
		2533	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2534
		2535	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2536	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2537	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2538	does nothing for those backends.
		2539
		2540	=item L<EV>
		2541
		2542	This module isn't really "optional", as it is simply one of the backend
		2543	event loops that AnyEvent can use. However, it is simply the best event
		2544	loop available in terms of features, speed and stability: It supports
		2545	the AnyEvent API optimally, implements all the watcher types in XS, does
		2546	automatic timer adjustments even when no monotonic clock is available,
		2547	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2548	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2549	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2550
		2551	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2552	then this module will do nothing for you.
		2553
		2554	=item L<Guard>
		2555
		2556	The guard module, when used, will be used to implement
		2557	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2558	lot less memory), but otherwise doesn't affect guard operation much. It is
		2559	purely used for performance.
		2560
		2561	=item L<JSON> and L<JSON::XS>
		2562
		2563	One of these modules is required when you want to read or write JSON data
		2564	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2565	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2566
		2567	=item L<Net::SSLeay>
		2568
		2569	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2570	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2571	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2572
		2573	=item L<Time::HiRes>
		2574
		2575	This module is part of perl since release 5.008. It will be used when the
		2576	chosen event library does not come with a timing source of its own. The
		2577	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2578	try to use a monotonic clock for timing stability.
		2579
		2580	=back
		2581
1827		2582
1828	=head1 FORK	2583	=head1 FORK
1829		2584
1830	Most event libraries are not fork-safe. The ones who are usually are	2585	Most event libraries are not fork-safe. The ones who are usually are
1831	because they rely on inefficient but fork-safe C<select> or C<poll>	2586	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1832	calls. Only L<EV> is fully fork-aware.	2587	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2588	are usually badly thought-out hacks that are incompatible with fork in
		2589	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2590	continue event-processing in both parent and child (or both, if you know
		2591	what you are doing).
		2592
		2593	This means that, in general, you cannot fork and do event processing in
		2594	the child if the event library was initialised before the fork (which
		2595	usually happens when the first AnyEvent watcher is created, or the library
		2596	is loaded).
1833		2597
1834	If you have to fork, you must either do so I<before> creating your first	2598	If you have to fork, you must either do so I<before> creating your first
1835	watcher OR you must not use AnyEvent at all in the child.	2599	watcher OR you must not use AnyEvent at all in the child OR you must do
		2600	something completely out of the scope of AnyEvent.
		2601
		2602	The problem of doing event processing in the parent I<and> the child
		2603	is much more complicated: even for backends that I<are> fork-aware or
		2604	fork-safe, their behaviour is not usually what you want: fork clones all
		2605	watchers, that means all timers, I/O watchers etc. are active in both
		2606	parent and child, which is almost never what you want. USing C<exec>
		2607	to start worker children from some kind of manage rprocess is usually
		2608	preferred, because it is much easier and cleaner, at the expense of having
		2609	to have another binary.
1836		2610
1837		2611
1838	=head1 SECURITY CONSIDERATIONS	2612	=head1 SECURITY CONSIDERATIONS
1839		2613
1840	AnyEvent can be forced to load any event model via	2614	AnyEvent can be forced to load any event model via
…		…
1852	use AnyEvent;	2626	use AnyEvent;
1853		2627
1854	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2628	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1855	be used to probe what backend is used and gain other information (which is	2629	be used to probe what backend is used and gain other information (which is
1856	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2630	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1857	$ENV{PERL_ANYEGENT_STRICT}.	2631	$ENV{PERL_ANYEVENT_STRICT}.
		2632
		2633	Note that AnyEvent will remove I<all> environment variables starting with
		2634	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2635	enabled.
1858		2636
1859		2637
1860	=head1 BUGS	2638	=head1 BUGS
1861		2639
1862	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2640	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1863	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2641	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1864	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2642	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1865	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2643	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1866	pronounced).	2644	pronounced).
1867		2645
1868		2646
1869	=head1 SEE ALSO	2647	=head1 SEE ALSO
		2648
		2649	Tutorial/Introduction: L<AnyEvent::Intro>.
		2650
		2651	FAQ: L<AnyEvent::FAQ>.
1870		2652
1871	Utility functions: L<AnyEvent::Util>.	2653	Utility functions: L<AnyEvent::Util>.
1872		2654
1873	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2655	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1874	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2656	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1875		2657
1876	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2658	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1877	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2659	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1878	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2660	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1879	L<AnyEvent::Impl::POE>.	2661	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1880		2662
1881	Non-blocking file handles, sockets, TCP clients and	2663	Non-blocking file handles, sockets, TCP clients and
1882	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2664	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1883		2665
1884	Asynchronous DNS: L<AnyEvent::DNS>.	2666	Asynchronous DNS: L<AnyEvent::DNS>.
1885		2667
1886	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2668	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1887		2669
1888	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2670	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2671	L<AnyEvent::HTTP>.
1889		2672
1890		2673
1891	=head1 AUTHOR	2674	=head1 AUTHOR
1892		2675
1893	Marc Lehmann <schmorp@schmorp.de>	2676	Marc Lehmann <schmorp@schmorp.de>

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