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Revision 1.103 by root, Tue Apr 29 07:15:49 2008 UTC vs.
Revision 1.180 by root, Sat Sep 6 07:00:45 2008 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });
		12
		13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		15
		16	print AnyEvent->now; # prints current event loop time
		17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		18
		19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		20
		21	my $w = AnyEvent->child (pid => $pid, cb => sub {
		22	my ($pid, $status) = @_;
12	...	23	...
13	});	24	});
14		25
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...
17	});
18
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	26	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		27	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	28	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	29	# use a condvar in callback mode:
		30	$w->cb (sub { $_[0]->recv });
		31
		32	=head1 INTRODUCTION/TUTORIAL
		33
		34	This manpage is mainly a reference manual. If you are interested
		35	in a tutorial or some gentle introduction, have a look at the
		36	L<AnyEvent::Intro> manpage.
22		37
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		39
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	41	nowadays. So what is different about AnyEvent?
27		42
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	43	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	44	policy> and AnyEvent is I<small and efficient>.
30		45
31	First and foremost, I<AnyEvent is not an event model> itself, it only	46	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	47	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	48	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	49	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	50	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	51	cannot change this, but it can hide the differences between those event
		52	loops.
37		53
38	The goal of AnyEvent is to offer module authors the ability to do event	54	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	55	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	56	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	57	module users into the same thing by forcing them to use the same event
42	model you use.	58	model you use.
43		59
44	For modules like POE or IO::Async (which is a total misnomer as it is	60	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	61	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	62	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	63	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	64	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	65	module are I<also> forced to use the same event loop you use.
50		66
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	68	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	69	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	70	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	71	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	72	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	73	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	74	to AnyEvent, too, so it is future-proof).
59		75
60	In addition to being free of having to use I<the one and only true event	76	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	77	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enourmous amount of code and strict rules you have to	78	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	79	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	80	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	81	technically possible.
66		82
		83	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		84	of useful functionality, such as an asynchronous DNS resolver, 100%
		85	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		86	such as Windows) and lots of real-world knowledge and workarounds for
		87	platform bugs and differences.
		88
67	Of course, if you want lots of policy (this can arguably be somewhat	89	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	90	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	91	model, you should I<not> use this module.
70		92
71	=head1 DESCRIPTION	93	=head1 DESCRIPTION
72		94
…		…
78	The interface itself is vaguely similar, but not identical to the L<Event>	100	The interface itself is vaguely similar, but not identical to the L<Event>
79	module.	101	module.
80		102
81	During the first call of any watcher-creation method, the module tries	103	During the first call of any watcher-creation method, the module tries
82	to detect the currently loaded event loop by probing whether one of the	104	to detect the currently loaded event loop by probing whether one of the
83	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	105	following modules is already loaded: L<EV>,
84	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	106	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
85	L<POE>. The first one found is used. If none are found, the module tries	107	L<POE>. The first one found is used. If none are found, the module tries
86	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	108	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
87	adaptor should always succeed) in the order given. The first one that can	109	adaptor should always succeed) in the order given. The first one that can
88	be successfully loaded will be used. If, after this, still none could be	110	be successfully loaded will be used. If, after this, still none could be
…		…
102	starts using it, all bets are off. Maybe you should tell their authors to	124	starts using it, all bets are off. Maybe you should tell their authors to
103	use AnyEvent so their modules work together with others seamlessly...	125	use AnyEvent so their modules work together with others seamlessly...
104		126
105	The pure-perl implementation of AnyEvent is called	127	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	128	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	129	explicitly and enjoy the high availability of that event loop :)
108		130
109	=head1 WATCHERS	131	=head1 WATCHERS
110		132
111	AnyEvent has the central concept of a I<watcher>, which is an object that	133	AnyEvent has the central concept of a I<watcher>, which is an object that
112	stores relevant data for each kind of event you are waiting for, such as	134	stores relevant data for each kind of event you are waiting for, such as
113	the callback to call, the filehandle to watch, etc.	135	the callback to call, the file handle to watch, etc.
114		136
115	These watchers are normal Perl objects with normal Perl lifetime. After	137	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	138	creating a watcher it will immediately "watch" for events and invoke the
117	callback when the event occurs (of course, only when the event model	139	callback when the event occurs (of course, only when the event model
118	is in control).	140	is in control).
…		…
126	Many watchers either are used with "recursion" (repeating timers for	148	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	149	example), or need to refer to their watcher object in other ways.
128		150
129	An any way to achieve that is this pattern:	151	An any way to achieve that is this pattern:
130		152
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	153	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	154	# you can use $w here, for example to undef it
133	undef $w;	155	undef $w;
134	});	156	});
135		157
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	158	Note that C<my $w; $w => combination. This is necessary because in Perl,
137	my variables are only visible after the statement in which they are	159	my variables are only visible after the statement in which they are
138	declared.	160	declared.
139		161
140	=head2 I/O WATCHERS	162	=head2 I/O WATCHERS
141		163
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	164	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	165	with the following mandatory key-value pairs as arguments:
144		166
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	167	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events
146	for events. C<poll> must be a string that is either C<r> or C<w>,	168	(AnyEvent might or might not keep a reference to this file handle). C<poll>
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	169	must be a string that is either C<r> or C<w>, which creates a watcher
148	respectively. C<cb> is the callback to invoke each time the file handle	170	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the
149	becomes ready.	171	callback to invoke each time the file handle becomes ready.
150		172
151	Although the callback might get passed parameters, their value and	173	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	174	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	175	callbacks cannot use arguments passed to I/O watcher callbacks.
154		176
…		…
158		180
159	Some event loops issue spurious readyness notifications, so you should	181	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	182	always use non-blocking calls when reading/writing from/to your file
161	handles.	183	handles.
162		184
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	185	Example: wait for readability of STDIN, then read a line and disable the
		186	watcher.
		187
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	188	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	189	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	190	warn "read: $input\n";
169	undef $w;	191	undef $w;
170	});	192	});
…		…
180		202
181	Although the callback might get passed parameters, their value and	203	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	204	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	205	callbacks cannot use arguments passed to time watcher callbacks.
184		206
185	The timer callback will be invoked at most once: if you want a repeating	207	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	208	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	209	callback will be invoked regularly at that interval (in fractional
		210	seconds) after the first invocation. If C<interval> is specified with a
		211	false value, then it is treated as if it were missing.
188		212
189	Example:	213	The callback will be rescheduled before invoking the callback, but no
		214	attempt is done to avoid timer drift in most backends, so the interval is
		215	only approximate.
190		216
191	# fire an event after 7.7 seconds	217	Example: fire an event after 7.7 seconds.
		218
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	219	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	220	warn "timeout\n";
194	});	221	});
195		222
196	# to cancel the timer:	223	# to cancel the timer:
197	undef $w;	224	undef $w;
198		225
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	226	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		227
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	228	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		229	warn "timeout\n";
207	};	230	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		231
212	=head3 TIMING ISSUES	232	=head3 TIMING ISSUES
213		233
214	There are two ways to handle timers: based on real time (relative, "fire	234	There are two ways to handle timers: based on real time (relative, "fire
215	in 10 seconds") and based on wallclock time (absolute, "fire at 12	235	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	247	timers.
228		248
229	AnyEvent always prefers relative timers, if available, matching the	249	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	250	AnyEvent API.
231		251
		252	AnyEvent has two additional methods that return the "current time":
		253
		254	=over 4
		255
		256	=item AnyEvent->time
		257
		258	This returns the "current wallclock time" as a fractional number of
		259	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		260	return, and the result is guaranteed to be compatible with those).
		261
		262	It progresses independently of any event loop processing, i.e. each call
		263	will check the system clock, which usually gets updated frequently.
		264
		265	=item AnyEvent->now
		266
		267	This also returns the "current wallclock time", but unlike C<time>, above,
		268	this value might change only once per event loop iteration, depending on
		269	the event loop (most return the same time as C<time>, above). This is the
		270	time that AnyEvent's timers get scheduled against.
		271
		272	I<In almost all cases (in all cases if you don't care), this is the
		273	function to call when you want to know the current time.>
		274
		275	This function is also often faster then C<< AnyEvent->time >>, and
		276	thus the preferred method if you want some timestamp (for example,
		277	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		278
		279	The rest of this section is only of relevance if you try to be very exact
		280	with your timing, you can skip it without bad conscience.
		281
		282	For a practical example of when these times differ, consider L<Event::Lib>
		283	and L<EV> and the following set-up:
		284
		285	The event loop is running and has just invoked one of your callback at
		286	time=500 (assume no other callbacks delay processing). In your callback,
		287	you wait a second by executing C<sleep 1> (blocking the process for a
		288	second) and then (at time=501) you create a relative timer that fires
		289	after three seconds.
		290
		291	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		292	both return C<501>, because that is the current time, and the timer will
		293	be scheduled to fire at time=504 (C<501> + C<3>).
		294
		295	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		296	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		297	last event processing phase started. With L<EV>, your timer gets scheduled
		298	to run at time=503 (C<500> + C<3>).
		299
		300	In one sense, L<Event::Lib> is more exact, as it uses the current time
		301	regardless of any delays introduced by event processing. However, most
		302	callbacks do not expect large delays in processing, so this causes a
		303	higher drift (and a lot more system calls to get the current time).
		304
		305	In another sense, L<EV> is more exact, as your timer will be scheduled at
		306	the same time, regardless of how long event processing actually took.
		307
		308	In either case, if you care (and in most cases, you don't), then you
		309	can get whatever behaviour you want with any event loop, by taking the
		310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		311	account.
		312
		313	=back
		314
232	=head2 SIGNAL WATCHERS	315	=head2 SIGNAL WATCHERS
233		316
234	You can watch for signals using a signal watcher, C<signal> is the signal	317	You can watch for signals using a signal watcher, C<signal> is the signal
235	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	318	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	319	callback to be invoked whenever a signal occurs.
237		320
238	Although the callback might get passed parameters, their value and	321	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	322	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	323	callbacks cannot use arguments passed to signal watcher callbacks.
241		324
242	Multiple signal occurances can be clumped together into one callback	325	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	326	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	327	that it might take a while until the signal gets handled by the process,
245	but it is guarenteed not to interrupt any other callbacks.	328	but it is guaranteed not to interrupt any other callbacks.
246		329
247	The main advantage of using these watchers is that you can share a signal	330	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	331	between multiple watchers.
249		332
250	This watcher might use C<%SIG>, so programs overwriting those signals	333	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
277	AnyEvent program, you I<have> to create at least one watcher before you	360	AnyEvent program, you I<have> to create at least one watcher before you
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	361	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		362
280	Example: fork a process and wait for it	363	Example: fork a process and wait for it
281		364
282	my $done = AnyEvent->condvar;	365	my $done = AnyEvent->condvar;
283		366
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	367	my $pid = fork or exit 5;
287		368
288	my $w = AnyEvent->child (	369	my $w = AnyEvent->child (
289	pid => $pid,	370	pid => $pid,
290	cb => sub {	371	cb => sub {
291	my ($pid, $status) = @_;	372	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	373	warn "pid $pid exited with status $status";
293	$done->broadcast;	374	$done->send;
294	},	375	},
295	);	376	);
296		377
297	# do something else, then wait for process exit	378	# do something else, then wait for process exit
298	$done->wait;	379	$done->recv;
299		380
300	=head2 CONDITION VARIABLES	381	=head2 CONDITION VARIABLES
301		382
		383	If you are familiar with some event loops you will know that all of them
		384	require you to run some blocking "loop", "run" or similar function that
		385	will actively watch for new events and call your callbacks.
		386
		387	AnyEvent is different, it expects somebody else to run the event loop and
		388	will only block when necessary (usually when told by the user).
		389
		390	The instrument to do that is called a "condition variable", so called
		391	because they represent a condition that must become true.
		392
302	Condition variables can be created by calling the C<< AnyEvent->condvar >>	393	Condition variables can be created by calling the C<< AnyEvent->condvar
303	method without any arguments.	394	>> method, usually without arguments. The only argument pair allowed is
304		395
305	A condition variable waits for a condition - precisely that the C<<	396	C<cb>, which specifies a callback to be called when the condition variable
306	->broadcast >> method has been called.	397	becomes true, with the condition variable as the first argument (but not
		398	the results).
307		399
308	They are very useful to signal that a condition has been fulfilled, for	400	After creation, the condition variable is "false" until it becomes "true"
		401	by calling the C<send> method (or calling the condition variable as if it
		402	were a callback, read about the caveats in the description for the C<<
		403	->send >> method).
		404
		405	Condition variables are similar to callbacks, except that you can
		406	optionally wait for them. They can also be called merge points - points
		407	in time where multiple outstanding events have been processed. And yet
		408	another way to call them is transactions - each condition variable can be
		409	used to represent a transaction, which finishes at some point and delivers
		410	a result.
		411
		412	Condition variables are very useful to signal that something has finished,
309	example, if you write a module that does asynchronous http requests,	413	for example, if you write a module that does asynchronous http requests,
310	then a condition variable would be the ideal candidate to signal the	414	then a condition variable would be the ideal candidate to signal the
311	availability of results.	415	availability of results. The user can either act when the callback is
		416	called or can synchronously C<< ->recv >> for the results.
312		417
313	You can also use condition variables to block your main program until	418	You can also use them to simulate traditional event loops - for example,
314	an event occurs - for example, you could C<< ->wait >> in your main	419	you can block your main program until an event occurs - for example, you
315	program until the user clicks the Quit button in your app, which would C<<	420	could C<< ->recv >> in your main program until the user clicks the Quit
316	->broadcast >> the "quit" event.	421	button of your app, which would C<< ->send >> the "quit" event.
317		422
318	Note that condition variables recurse into the event loop - if you have	423	Note that condition variables recurse into the event loop - if you have
319	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	424	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
320	lose. Therefore, condition variables are good to export to your caller, but	425	lose. Therefore, condition variables are good to export to your caller, but
321	you should avoid making a blocking wait yourself, at least in callbacks,	426	you should avoid making a blocking wait yourself, at least in callbacks,
322	as this asks for trouble.	427	as this asks for trouble.
323		428
324	This object has two methods:	429	Condition variables are represented by hash refs in perl, and the keys
		430	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		431	easy (it is often useful to build your own transaction class on top of
		432	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		433	it's C<new> method in your own C<new> method.
		434
		435	There are two "sides" to a condition variable - the "producer side" which
		436	eventually calls C<< -> send >>, and the "consumer side", which waits
		437	for the send to occur.
		438
		439	Example: wait for a timer.
		440
		441	# wait till the result is ready
		442	my $result_ready = AnyEvent->condvar;
		443
		444	# do something such as adding a timer
		445	# or socket watcher the calls $result_ready->send
		446	# when the "result" is ready.
		447	# in this case, we simply use a timer:
		448	my $w = AnyEvent->timer (
		449	after => 1,
		450	cb => sub { $result_ready->send },
		451	);
		452
		453	# this "blocks" (while handling events) till the callback
		454	# calls send
		455	$result_ready->recv;
		456
		457	Example: wait for a timer, but take advantage of the fact that
		458	condition variables are also code references.
		459
		460	my $done = AnyEvent->condvar;
		461	my $delay = AnyEvent->timer (after => 5, cb => $done);
		462	$done->recv;
		463
		464	Example: Imagine an API that returns a condvar and doesn't support
		465	callbacks. This is how you make a synchronous call, for example from
		466	the main program:
		467
		468	use AnyEvent::CouchDB;
		469
		470	...
		471
		472	my @info = $couchdb->info->recv;
		473
		474	And this is how you would just ste a callback to be called whenever the
		475	results are available:
		476
		477	$couchdb->info->cb (sub {
		478	my @info = $_[0]->recv;
		479	});
		480
		481	=head3 METHODS FOR PRODUCERS
		482
		483	These methods should only be used by the producing side, i.e. the
		484	code/module that eventually sends the signal. Note that it is also
		485	the producer side which creates the condvar in most cases, but it isn't
		486	uncommon for the consumer to create it as well.
325		487
326	=over 4	488	=over 4
327		489
		490	=item $cv->send (...)
		491
		492	Flag the condition as ready - a running C<< ->recv >> and all further
		493	calls to C<recv> will (eventually) return after this method has been
		494	called. If nobody is waiting the send will be remembered.
		495
		496	If a callback has been set on the condition variable, it is called
		497	immediately from within send.
		498
		499	Any arguments passed to the C<send> call will be returned by all
		500	future C<< ->recv >> calls.
		501
		502	Condition variables are overloaded so one can call them directly
		503	(as a code reference). Calling them directly is the same as calling
		504	C<send>. Note, however, that many C-based event loops do not handle
		505	overloading, so as tempting as it may be, passing a condition variable
		506	instead of a callback does not work. Both the pure perl and EV loops
		507	support overloading, however, as well as all functions that use perl to
		508	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		509	example).
		510
		511	=item $cv->croak ($error)
		512
		513	Similar to send, but causes all call's to C<< ->recv >> to invoke
		514	C<Carp::croak> with the given error message/object/scalar.
		515
		516	This can be used to signal any errors to the condition variable
		517	user/consumer.
		518
		519	=item $cv->begin ([group callback])
		520
328	=item $cv->wait	521	=item $cv->end
329		522
330	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	523	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		524
		525	These two methods can be used to combine many transactions/events into
		526	one. For example, a function that pings many hosts in parallel might want
		527	to use a condition variable for the whole process.
		528
		529	Every call to C<< ->begin >> will increment a counter, and every call to
		530	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		531	>>, the (last) callback passed to C<begin> will be executed. That callback
		532	is I<supposed> to call C<< ->send >>, but that is not required. If no
		533	callback was set, C<send> will be called without any arguments.
		534
		535	Let's clarify this with the ping example:
		536
		537	my $cv = AnyEvent->condvar;
		538
		539	my %result;
		540	$cv->begin (sub { $cv->send (\%result) });
		541
		542	for my $host (@list_of_hosts) {
		543	$cv->begin;
		544	ping_host_then_call_callback $host, sub {
		545	$result{$host} = ...;
		546	$cv->end;
		547	};
		548	}
		549
		550	$cv->end;
		551
		552	This code fragment supposedly pings a number of hosts and calls
		553	C<send> after results for all then have have been gathered - in any
		554	order. To achieve this, the code issues a call to C<begin> when it starts
		555	each ping request and calls C<end> when it has received some result for
		556	it. Since C<begin> and C<end> only maintain a counter, the order in which
		557	results arrive is not relevant.
		558
		559	There is an additional bracketing call to C<begin> and C<end> outside the
		560	loop, which serves two important purposes: first, it sets the callback
		561	to be called once the counter reaches C<0>, and second, it ensures that
		562	C<send> is called even when C<no> hosts are being pinged (the loop
		563	doesn't execute once).
		564
		565	This is the general pattern when you "fan out" into multiple subrequests:
		566	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		567	is called at least once, and then, for each subrequest you start, call
		568	C<begin> and for each subrequest you finish, call C<end>.
		569
		570	=back
		571
		572	=head3 METHODS FOR CONSUMERS
		573
		574	These methods should only be used by the consuming side, i.e. the
		575	code awaits the condition.
		576
		577	=over 4
		578
		579	=item $cv->recv
		580
		581	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
331	called on c<$cv>, while servicing other watchers normally.	582	>> methods have been called on c<$cv>, while servicing other watchers
		583	normally.
332		584
333	You can only wait once on a condition - additional calls will return	585	You can only wait once on a condition - additional calls are valid but
334	immediately.	586	will return immediately.
		587
		588	If an error condition has been set by calling C<< ->croak >>, then this
		589	function will call C<croak>.
		590
		591	In list context, all parameters passed to C<send> will be returned,
		592	in scalar context only the first one will be returned.
335		593
336	Not all event models support a blocking wait - some die in that case	594	Not all event models support a blocking wait - some die in that case
337	(programs might want to do that to stay interactive), so I<if you are	595	(programs might want to do that to stay interactive), so I<if you are
338	using this from a module, never require a blocking wait>, but let the	596	using this from a module, never require a blocking wait>, but let the
339	caller decide whether the call will block or not (for example, by coupling	597	caller decide whether the call will block or not (for example, by coupling
340	condition variables with some kind of request results and supporting	598	condition variables with some kind of request results and supporting
341	callbacks so the caller knows that getting the result will not block,	599	callbacks so the caller knows that getting the result will not block,
342	while still suppporting blocking waits if the caller so desires).	600	while still supporting blocking waits if the caller so desires).
343		601
344	Another reason I<never> to C<< ->wait >> in a module is that you cannot	602	Another reason I<never> to C<< ->recv >> in a module is that you cannot
345	sensibly have two C<< ->wait >>'s in parallel, as that would require	603	sensibly have two C<< ->recv >>'s in parallel, as that would require
346	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	604	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
347	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	605	can supply.
348	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
349	from different coroutines, however).
350		606
351	=item $cv->broadcast	607	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		608	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		609	versions and also integrates coroutines into AnyEvent, making blocking
		610	C<< ->recv >> calls perfectly safe as long as they are done from another
		611	coroutine (one that doesn't run the event loop).
352		612
353	Flag the condition as ready - a running C<< ->wait >> and all further	613	You can ensure that C<< -recv >> never blocks by setting a callback and
354	calls to C<wait> will (eventually) return after this method has been	614	only calling C<< ->recv >> from within that callback (or at a later
355	called. If nobody is waiting the broadcast will be remembered..	615	time). This will work even when the event loop does not support blocking
		616	waits otherwise.
		617
		618	=item $bool = $cv->ready
		619
		620	Returns true when the condition is "true", i.e. whether C<send> or
		621	C<croak> have been called.
		622
		623	=item $cb = $cv->cb ($cb->($cv))
		624
		625	This is a mutator function that returns the callback set and optionally
		626	replaces it before doing so.
		627
		628	The callback will be called when the condition becomes "true", i.e. when
		629	C<send> or C<croak> are called, with the only argument being the condition
		630	variable itself. Calling C<recv> inside the callback or at any later time
		631	is guaranteed not to block.
356		632
357	=back	633	=back
358
359	Example:
360
361	# wait till the result is ready
362	my $result_ready = AnyEvent->condvar;
363
364	# do something such as adding a timer
365	# or socket watcher the calls $result_ready->broadcast
366	# when the "result" is ready.
367	# in this case, we simply use a timer:
368	my $w = AnyEvent->timer (
369	after => 1,
370	cb => sub { $result_ready->broadcast },
371	);
372
373	# this "blocks" (while handling events) till the watcher
374	# calls broadcast
375	$result_ready->wait;
376		634
377	=head1 GLOBAL VARIABLES AND FUNCTIONS	635	=head1 GLOBAL VARIABLES AND FUNCTIONS
378		636
379	=over 4	637	=over 4
380		638
…		…
386	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	644	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
387	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	645	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
388		646
389	The known classes so far are:	647	The known classes so far are:
390		648
391	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
392	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
393	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	649	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
394	AnyEvent::Impl::Event based on Event, second best choice.	650	AnyEvent::Impl::Event based on Event, second best choice.
		651	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
395	AnyEvent::Impl::Glib based on Glib, third-best choice.	652	AnyEvent::Impl::Glib based on Glib, third-best choice.
396	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
397	AnyEvent::Impl::Tk based on Tk, very bad choice.	653	AnyEvent::Impl::Tk based on Tk, very bad choice.
398	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	654	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
399	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	655	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
400	AnyEvent::Impl::POE based on POE, not generic enough for full support.	656	AnyEvent::Impl::POE based on POE, not generic enough for full support.
401		657
…		…
414	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	670	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
415	if necessary. You should only call this function right before you would	671	if necessary. You should only call this function right before you would
416	have created an AnyEvent watcher anyway, that is, as late as possible at	672	have created an AnyEvent watcher anyway, that is, as late as possible at
417	runtime.	673	runtime.
418		674
		675	=item $guard = AnyEvent::post_detect { BLOCK }
		676
		677	Arranges for the code block to be executed as soon as the event model is
		678	autodetected (or immediately if this has already happened).
		679
		680	If called in scalar or list context, then it creates and returns an object
		681	that automatically removes the callback again when it is destroyed. See
		682	L<Coro::BDB> for a case where this is useful.
		683
		684	=item @AnyEvent::post_detect
		685
		686	If there are any code references in this array (you can C<push> to it
		687	before or after loading AnyEvent), then they will called directly after
		688	the event loop has been chosen.
		689
		690	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		691	if it contains a true value then the event loop has already been detected,
		692	and the array will be ignored.
		693
		694	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		695
419	=back	696	=back
420		697
421	=head1 WHAT TO DO IN A MODULE	698	=head1 WHAT TO DO IN A MODULE
422		699
423	As a module author, you should C<use AnyEvent> and call AnyEvent methods	700	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
426	Be careful when you create watchers in the module body - AnyEvent will	703	Be careful when you create watchers in the module body - AnyEvent will
427	decide which event module to use as soon as the first method is called, so	704	decide which event module to use as soon as the first method is called, so
428	by calling AnyEvent in your module body you force the user of your module	705	by calling AnyEvent in your module body you force the user of your module
429	to load the event module first.	706	to load the event module first.
430		707
431	Never call C<< ->wait >> on a condition variable unless you I<know> that	708	Never call C<< ->recv >> on a condition variable unless you I<know> that
432	the C<< ->broadcast >> method has been called on it already. This is	709	the C<< ->send >> method has been called on it already. This is
433	because it will stall the whole program, and the whole point of using	710	because it will stall the whole program, and the whole point of using
434	events is to stay interactive.	711	events is to stay interactive.
435		712
436	It is fine, however, to call C<< ->wait >> when the user of your module	713	It is fine, however, to call C<< ->recv >> when the user of your module
437	requests it (i.e. if you create a http request object ad have a method	714	requests it (i.e. if you create a http request object ad have a method
438	called C<results> that returns the results, it should call C<< ->wait >>	715	called C<results> that returns the results, it should call C<< ->recv >>
439	freely, as the user of your module knows what she is doing. always).	716	freely, as the user of your module knows what she is doing. always).
440		717
441	=head1 WHAT TO DO IN THE MAIN PROGRAM	718	=head1 WHAT TO DO IN THE MAIN PROGRAM
442		719
443	There will always be a single main program - the only place that should	720	There will always be a single main program - the only place that should
…		…
445		722
446	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	723	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
447	do anything special (it does not need to be event-based) and let AnyEvent	724	do anything special (it does not need to be event-based) and let AnyEvent
448	decide which implementation to chose if some module relies on it.	725	decide which implementation to chose if some module relies on it.
449		726
450	If the main program relies on a specific event model. For example, in	727	If the main program relies on a specific event model - for example, in
451	Gtk2 programs you have to rely on the Glib module. You should load the	728	Gtk2 programs you have to rely on the Glib module - you should load the
452	event module before loading AnyEvent or any module that uses it: generally	729	event module before loading AnyEvent or any module that uses it: generally
453	speaking, you should load it as early as possible. The reason is that	730	speaking, you should load it as early as possible. The reason is that
454	modules might create watchers when they are loaded, and AnyEvent will	731	modules might create watchers when they are loaded, and AnyEvent will
455	decide on the event model to use as soon as it creates watchers, and it	732	decide on the event model to use as soon as it creates watchers, and it
456	might chose the wrong one unless you load the correct one yourself.	733	might chose the wrong one unless you load the correct one yourself.
457		734
458	You can chose to use a rather inefficient pure-perl implementation by	735	You can chose to use a pure-perl implementation by loading the
459	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	736	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
460	behaviour everywhere, but letting AnyEvent chose is generally better.	737	everywhere, but letting AnyEvent chose the model is generally better.
		738
		739	=head2 MAINLOOP EMULATION
		740
		741	Sometimes (often for short test scripts, or even standalone programs who
		742	only want to use AnyEvent), you do not want to run a specific event loop.
		743
		744	In that case, you can use a condition variable like this:
		745
		746	AnyEvent->condvar->recv;
		747
		748	This has the effect of entering the event loop and looping forever.
		749
		750	Note that usually your program has some exit condition, in which case
		751	it is better to use the "traditional" approach of storing a condition
		752	variable somewhere, waiting for it, and sending it when the program should
		753	exit cleanly.
		754
461		755
462	=head1 OTHER MODULES	756	=head1 OTHER MODULES
463		757
464	The following is a non-exhaustive list of additional modules that use	758	The following is a non-exhaustive list of additional modules that use
465	AnyEvent and can therefore be mixed easily with other AnyEvent modules	759	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
471	=item L<AnyEvent::Util>	765	=item L<AnyEvent::Util>
472		766
473	Contains various utility functions that replace often-used but blocking	767	Contains various utility functions that replace often-used but blocking
474	functions such as C<inet_aton> by event-/callback-based versions.	768	functions such as C<inet_aton> by event-/callback-based versions.
475		769
		770	=item L<AnyEvent::Socket>
		771
		772	Provides various utility functions for (internet protocol) sockets,
		773	addresses and name resolution. Also functions to create non-blocking tcp
		774	connections or tcp servers, with IPv6 and SRV record support and more.
		775
476	=item L<AnyEvent::Handle>	776	=item L<AnyEvent::Handle>
477		777
478	Provide read and write buffers and manages watchers for reads and writes.	778	Provide read and write buffers, manages watchers for reads and writes,
		779	supports raw and formatted I/O, I/O queued and fully transparent and
		780	non-blocking SSL/TLS.
479		781
480	=item L<AnyEvent::Socket>	782	=item L<AnyEvent::DNS>
481		783
482	Provides a means to do non-blocking connects, accepts etc.	784	Provides rich asynchronous DNS resolver capabilities.
		785
		786	=item L<AnyEvent::HTTP>
		787
		788	A simple-to-use HTTP library that is capable of making a lot of concurrent
		789	HTTP requests.
483		790
484	=item L<AnyEvent::HTTPD>	791	=item L<AnyEvent::HTTPD>
485		792
486	Provides a simple web application server framework.	793	Provides a simple web application server framework.
487		794
488	=item L<AnyEvent::DNS>
489
490	Provides asynchronous DNS resolver capabilities, beyond what
491	L<AnyEvent::Util> offers.
492
493	=item L<AnyEvent::FastPing>	795	=item L<AnyEvent::FastPing>
494		796
495	The fastest ping in the west.	797	The fastest ping in the west.
		798
		799	=item L<AnyEvent::DBI>
		800
		801	Executes L<DBI> requests asynchronously in a proxy process.
		802
		803	=item L<AnyEvent::AIO>
		804
		805	Truly asynchronous I/O, should be in the toolbox of every event
		806	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		807	together.
		808
		809	=item L<AnyEvent::BDB>
		810
		811	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		812	L<BDB> and AnyEvent together.
		813
		814	=item L<AnyEvent::GPSD>
		815
		816	A non-blocking interface to gpsd, a daemon delivering GPS information.
		817
		818	=item L<AnyEvent::IGS>
		819
		820	A non-blocking interface to the Internet Go Server protocol (used by
		821	L<App::IGS>).
496		822
497	=item L<Net::IRC3>	823	=item L<Net::IRC3>
498		824
499	AnyEvent based IRC client module family.	825	AnyEvent based IRC client module family.
500		826
…		…
511		837
512	High level API for event-based execution flow control.	838	High level API for event-based execution flow control.
513		839
514	=item L<Coro>	840	=item L<Coro>
515		841
516	Has special support for AnyEvent.	842	Has special support for AnyEvent via L<Coro::AnyEvent>.
517		843
518	=item L<IO::Lambda>	844	=item L<IO::Lambda>
519		845
520	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	846	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
521		847
522	=item L<IO::AIO>
523
524	Truly asynchronous I/O, should be in the toolbox of every event
525	programmer. Can be trivially made to use AnyEvent.
526
527	=item L<BDB>
528
529	Truly asynchronous Berkeley DB access. Can be trivially made to use
530	AnyEvent.
531
532	=back	848	=back
533		849
534	=cut	850	=cut
535		851
536	package AnyEvent;	852	package AnyEvent;
537		853
538	no warnings;	854	no warnings;
539	use strict;	855	use strict qw(vars subs);
540		856
541	use Carp;	857	use Carp;
542		858
543	our $VERSION = '3.3';	859	our $VERSION = 4.233;
544	our $MODEL;	860	our $MODEL;
545		861
546	our $AUTOLOAD;	862	our $AUTOLOAD;
547	our @ISA;	863	our @ISA;
548		864
		865	our @REGISTRY;
		866
		867	our $WIN32;
		868
		869	BEGIN {
		870	my $win32 = ! ! ($^O =~ /mswin32/i);
		871	eval "sub WIN32(){ $win32 }";
		872	}
		873
549	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	874	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
550		875
551	our @REGISTRY;	876	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		877
		878	{
		879	my $idx;
		880	$PROTOCOL{$_} = ++$idx
		881	for reverse split /\s*,\s*/,
		882	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		883	}
552		884
553	my @models = (	885	my @models = (
554	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
555	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
556	[EV:: => AnyEvent::Impl::EV::],	886	[EV:: => AnyEvent::Impl::EV::],
557	[Event:: => AnyEvent::Impl::Event::],	887	[Event:: => AnyEvent::Impl::Event::],
558	[Glib:: => AnyEvent::Impl::Glib::],
559	[Tk:: => AnyEvent::Impl::Tk::],
560	[Wx:: => AnyEvent::Impl::POE::],
561	[Prima:: => AnyEvent::Impl::POE::],
562	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	888	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
563	# everything below here will not be autoprobed as the pureperl backend should work everywhere	889	# everything below here will not be autoprobed
		890	# as the pureperl backend should work everywhere
		891	# and is usually faster
		892	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		893	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
564	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	894	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
565	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	895	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
566	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	896	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		897	[Wx:: => AnyEvent::Impl::POE::],
		898	[Prima:: => AnyEvent::Impl::POE::],
567	);	899	);
568		900
569	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	901	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		902
		903	our @post_detect;
		904
		905	sub post_detect(&) {
		906	my ($cb) = @_;
		907
		908	if ($MODEL) {
		909	$cb->();
		910
		911	1
		912	} else {
		913	push @post_detect, $cb;
		914
		915	defined wantarray
		916	? bless \$cb, "AnyEvent::Util::PostDetect"
		917	: ()
		918	}
		919	}
		920
		921	sub AnyEvent::Util::PostDetect::DESTROY {
		922	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		923	}
570		924
571	sub detect() {	925	sub detect() {
572	unless ($MODEL) {	926	unless ($MODEL) {
573	no strict 'refs';	927	no strict 'refs';
		928	local $SIG{__DIE__};
574		929
575	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	930	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
576	my $model = "AnyEvent::Impl::$1";	931	my $model = "AnyEvent::Impl::$1";
577	if (eval "require $model") {	932	if (eval "require $model") {
578	$MODEL = $model;	933	$MODEL = $model;
…		…
608	last;	963	last;
609	}	964	}
610	}	965	}
611		966
612	$MODEL	967	$MODEL
613	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	968	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
614	}	969	}
615	}	970	}
616		971
		972	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		973
617	unshift @ISA, $MODEL;	974	unshift @ISA, $MODEL;
618	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	975
		976	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		977
		978	(shift @post_detect)->() while @post_detect;
619	}	979	}
620		980
621	$MODEL	981	$MODEL
622	}	982	}
623		983
…		…
631		991
632	my $class = shift;	992	my $class = shift;
633	$class->$func (@_);	993	$class->$func (@_);
634	}	994	}
635		995
		996	# utility function to dup a filehandle. this is used by many backends
		997	# to support binding more than one watcher per filehandle (they usually
		998	# allow only one watcher per fd, so we dup it to get a different one).
		999	sub _dupfh($$$$) {
		1000	my ($poll, $fh, $r, $w) = @_;
		1001
		1002	require Fcntl;
		1003
		1004	# cygwin requires the fh mode to be matching, unix doesn't
		1005	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1006	: $poll eq "w" ? ($w, ">")
		1007	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1008
		1009	open my $fh2, "$mode&" . fileno $fh
		1010	or die "cannot dup() filehandle: $!";
		1011
		1012	# we assume CLOEXEC is already set by perl in all important cases
		1013
		1014	($fh2, $rw)
		1015	}
		1016
636	package AnyEvent::Base;	1017	package AnyEvent::Base;
637		1018
		1019	# default implementation for now and time
		1020
		1021	BEGIN {
		1022	if (eval "use Time::HiRes (); time (); 1") {
		1023	*_time = \&Time::HiRes::time;
		1024	# if (eval "use POSIX (); (POSIX::times())...
		1025	} else {
		1026	*_time = \&CORE::time; # epic fail
		1027	}
		1028	}
		1029
		1030	sub time { _time }
		1031	sub now { _time }
		1032
638	# default implementation for ->condvar, ->wait, ->broadcast	1033	# default implementation for ->condvar
639		1034
640	sub condvar {	1035	sub condvar {
641	bless \my $flag, "AnyEvent::Base::CondVar"	1036	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
642	}
643
644	sub AnyEvent::Base::CondVar::broadcast {
645	${$_[0]}++;
646	}
647
648	sub AnyEvent::Base::CondVar::wait {
649	AnyEvent->one_event while !${$_[0]};
650	}	1037	}
651		1038
652	# default implementation for ->signal	1039	# default implementation for ->signal
653		1040
654	our %SIG_CB;	1041	our %SIG_CB;
…		…
670	sub AnyEvent::Base::Signal::DESTROY {	1057	sub AnyEvent::Base::Signal::DESTROY {
671	my ($signal, $cb) = @{$_[0]};	1058	my ($signal, $cb) = @{$_[0]};
672		1059
673	delete $SIG_CB{$signal}{$cb};	1060	delete $SIG_CB{$signal}{$cb};
674		1061
675	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1062	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
676	}	1063	}
677		1064
678	# default implementation for ->child	1065	# default implementation for ->child
679		1066
680	our %PID_CB;	1067	our %PID_CB;
…		…
707	or Carp::croak "required option 'pid' is missing";	1094	or Carp::croak "required option 'pid' is missing";
708		1095
709	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1096	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
710		1097
711	unless ($WNOHANG) {	1098	unless ($WNOHANG) {
712	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1099	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
713	}	1100	}
714		1101
715	unless ($CHLD_W) {	1102	unless ($CHLD_W) {
716	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1103	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
717	# child could be a zombie already, so make at least one round	1104	# child could be a zombie already, so make at least one round
…		…
727	delete $PID_CB{$pid}{$cb};	1114	delete $PID_CB{$pid}{$cb};
728	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1115	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
729		1116
730	undef $CHLD_W unless keys %PID_CB;	1117	undef $CHLD_W unless keys %PID_CB;
731	}	1118	}
		1119
		1120	package AnyEvent::CondVar;
		1121
		1122	our @ISA = AnyEvent::CondVar::Base::;
		1123
		1124	package AnyEvent::CondVar::Base;
		1125
		1126	use overload
		1127	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1128	fallback => 1;
		1129
		1130	sub _send {
		1131	# nop
		1132	}
		1133
		1134	sub send {
		1135	my $cv = shift;
		1136	$cv->{_ae_sent} = [@_];
		1137	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1138	$cv->_send;
		1139	}
		1140
		1141	sub croak {
		1142	$_[0]{_ae_croak} = $_[1];
		1143	$_[0]->send;
		1144	}
		1145
		1146	sub ready {
		1147	$_[0]{_ae_sent}
		1148	}
		1149
		1150	sub _wait {
		1151	AnyEvent->one_event while !$_[0]{_ae_sent};
		1152	}
		1153
		1154	sub recv {
		1155	$_[0]->_wait;
		1156
		1157	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1158	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1159	}
		1160
		1161	sub cb {
		1162	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1163	$_[0]{_ae_cb}
		1164	}
		1165
		1166	sub begin {
		1167	++$_[0]{_ae_counter};
		1168	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1169	}
		1170
		1171	sub end {
		1172	return if --$_[0]{_ae_counter};
		1173	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1174	}
		1175
		1176	# undocumented/compatibility with pre-3.4
		1177	*broadcast = \&send;
		1178	*wait = \&_wait;
		1179
		1180	=head1 ERROR AND EXCEPTION HANDLING
		1181
		1182	In general, AnyEvent does not do any error handling - it relies on the
		1183	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1184	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1185	checking of all AnyEvent methods, however, which is highly useful during
		1186	development.
		1187
		1188	As for exception handling (i.e. runtime errors and exceptions thrown while
		1189	executing a callback), this is not only highly event-loop specific, but
		1190	also not in any way wrapped by this module, as this is the job of the main
		1191	program.
		1192
		1193	The pure perl event loop simply re-throws the exception (usually
		1194	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1195	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1196	so on.
		1197
		1198	=head1 ENVIRONMENT VARIABLES
		1199
		1200	The following environment variables are used by this module or its
		1201	submodules:
		1202
		1203	=over 4
		1204
		1205	=item C<PERL_ANYEVENT_VERBOSE>
		1206
		1207	By default, AnyEvent will be completely silent except in fatal
		1208	conditions. You can set this environment variable to make AnyEvent more
		1209	talkative.
		1210
		1211	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1212	conditions, such as not being able to load the event model specified by
		1213	C<PERL_ANYEVENT_MODEL>.
		1214
		1215	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1216	model it chooses.
		1217
		1218	=item C<PERL_ANYEVENT_STRICT>
		1219
		1220	AnyEvent does not do much argument checking by default, as thorough
		1221	argument checking is very costly. Setting this variable to a true value
		1222	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1223	check the arguments passed to most method calls. If it finds any problems
		1224	it will croak.
		1225
		1226	In other words, enables "strict" mode.
		1227
		1228	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1229	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1230	developing programs can be very useful, however.
		1231
		1232	=item C<PERL_ANYEVENT_MODEL>
		1233
		1234	This can be used to specify the event model to be used by AnyEvent, before
		1235	auto detection and -probing kicks in. It must be a string consisting
		1236	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1237	and the resulting module name is loaded and if the load was successful,
		1238	used as event model. If it fails to load AnyEvent will proceed with
		1239	auto detection and -probing.
		1240
		1241	This functionality might change in future versions.
		1242
		1243	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1244	could start your program like this:
		1245
		1246	PERL_ANYEVENT_MODEL=Perl perl ...
		1247
		1248	=item C<PERL_ANYEVENT_PROTOCOLS>
		1249
		1250	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1251	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1252	of auto probing).
		1253
		1254	Must be set to a comma-separated list of protocols or address families,
		1255	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1256	used, and preference will be given to protocols mentioned earlier in the
		1257	list.
		1258
		1259	This variable can effectively be used for denial-of-service attacks
		1260	against local programs (e.g. when setuid), although the impact is likely
		1261	small, as the program has to handle connection errors already-
		1262
		1263	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1264	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1265	- only support IPv4, never try to resolve or contact IPv6
		1266	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1267	IPv6, but prefer IPv6 over IPv4.
		1268
		1269	=item C<PERL_ANYEVENT_EDNS0>
		1270
		1271	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1272	for DNS. This extension is generally useful to reduce DNS traffic, but
		1273	some (broken) firewalls drop such DNS packets, which is why it is off by
		1274	default.
		1275
		1276	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1277	EDNS0 in its DNS requests.
		1278
		1279	=item C<PERL_ANYEVENT_MAX_FORKS>
		1280
		1281	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1282	will create in parallel.
		1283
		1284	=back
732		1285
733	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1286	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
734		1287
735	This is an advanced topic that you do not normally need to use AnyEvent in	1288	This is an advanced topic that you do not normally need to use AnyEvent in
736	a module. This section is only of use to event loop authors who want to	1289	a module. This section is only of use to event loop authors who want to
…		…
770		1323
771	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1324	I<rxvt-unicode> also cheats a bit by not providing blocking access to
772	condition variables: code blocking while waiting for a condition will	1325	condition variables: code blocking while waiting for a condition will
773	C<die>. This still works with most modules/usages, and blocking calls must	1326	C<die>. This still works with most modules/usages, and blocking calls must
774	not be done in an interactive application, so it makes sense.	1327	not be done in an interactive application, so it makes sense.
775
776	=head1 ENVIRONMENT VARIABLES
777
778	The following environment variables are used by this module:
779
780	=over 4
781
782	=item C<PERL_ANYEVENT_VERBOSE>
783
784	By default, AnyEvent will be completely silent except in fatal
785	conditions. You can set this environment variable to make AnyEvent more
786	talkative.
787
788	When set to C<1> or higher, causes AnyEvent to warn about unexpected
789	conditions, such as not being able to load the event model specified by
790	C<PERL_ANYEVENT_MODEL>.
791
792	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
793	model it chooses.
794
795	=item C<PERL_ANYEVENT_MODEL>
796
797	This can be used to specify the event model to be used by AnyEvent, before
798	autodetection and -probing kicks in. It must be a string consisting
799	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
800	and the resulting module name is loaded and if the load was successful,
801	used as event model. If it fails to load AnyEvent will proceed with
802	autodetection and -probing.
803
804	This functionality might change in future versions.
805
806	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
807	could start your program like this:
808
809	PERL_ANYEVENT_MODEL=Perl perl ...
810
811	=back
812		1328
813	=head1 EXAMPLE PROGRAM	1329	=head1 EXAMPLE PROGRAM
814		1330
815	The following program uses an I/O watcher to read data from STDIN, a timer	1331	The following program uses an I/O watcher to read data from STDIN, a timer
816	to display a message once per second, and a condition variable to quit the	1332	to display a message once per second, and a condition variable to quit the
…		…
825	poll => 'r',	1341	poll => 'r',
826	cb => sub {	1342	cb => sub {
827	warn "io event <$_[0]>\n"; # will always output <r>	1343	warn "io event <$_[0]>\n"; # will always output <r>
828	chomp (my $input = <STDIN>); # read a line	1344	chomp (my $input = <STDIN>); # read a line
829	warn "read: $input\n"; # output what has been read	1345	warn "read: $input\n"; # output what has been read
830	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1346	$cv->send if $input =~ /^q/i; # quit program if /^q/i
831	},	1347	},
832	);	1348	);
833		1349
834	my $time_watcher; # can only be used once	1350	my $time_watcher; # can only be used once
835		1351
…		…
840	});	1356	});
841	}	1357	}
842		1358
843	new_timer; # create first timer	1359	new_timer; # create first timer
844		1360
845	$cv->wait; # wait until user enters /^q/i	1361	$cv->recv; # wait until user enters /^q/i
846		1362
847	=head1 REAL-WORLD EXAMPLE	1363	=head1 REAL-WORLD EXAMPLE
848		1364
849	Consider the L<Net::FCP> module. It features (among others) the following	1365	Consider the L<Net::FCP> module. It features (among others) the following
850	API calls, which are to freenet what HTTP GET requests are to http:	1366	API calls, which are to freenet what HTTP GET requests are to http:
…		…
900	syswrite $txn->{fh}, $txn->{request}	1416	syswrite $txn->{fh}, $txn->{request}
901	or die "connection or write error";	1417	or die "connection or write error";
902	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1418	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
903		1419
904	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1420	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
905	result and signals any possible waiters that the request ahs finished:	1421	result and signals any possible waiters that the request has finished:
906		1422
907	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1423	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
908		1424
909	if (end-of-file or data complete) {	1425	if (end-of-file or data complete) {
910	$txn->{result} = $txn->{buf};	1426	$txn->{result} = $txn->{buf};
911	$txn->{finished}->broadcast;	1427	$txn->{finished}->send;
912	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1428	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
913	}	1429	}
914		1430
915	The C<result> method, finally, just waits for the finished signal (if the	1431	The C<result> method, finally, just waits for the finished signal (if the
916	request was already finished, it doesn't wait, of course, and returns the	1432	request was already finished, it doesn't wait, of course, and returns the
917	data:	1433	data:
918		1434
919	$txn->{finished}->wait;	1435	$txn->{finished}->recv;
920	return $txn->{result};	1436	return $txn->{result};
921		1437
922	The actual code goes further and collects all errors (C<die>s, exceptions)	1438	The actual code goes further and collects all errors (C<die>s, exceptions)
923	that occured during request processing. The C<result> method detects	1439	that occurred during request processing. The C<result> method detects
924	whether an exception as thrown (it is stored inside the $txn object)	1440	whether an exception as thrown (it is stored inside the $txn object)
925	and just throws the exception, which means connection errors and other	1441	and just throws the exception, which means connection errors and other
926	problems get reported tot he code that tries to use the result, not in a	1442	problems get reported tot he code that tries to use the result, not in a
927	random callback.	1443	random callback.
928		1444
…		…
959		1475
960	my $quit = AnyEvent->condvar;	1476	my $quit = AnyEvent->condvar;
961		1477
962	$fcp->txn_client_get ($url)->cb (sub {	1478	$fcp->txn_client_get ($url)->cb (sub {
963	...	1479	...
964	$quit->broadcast;	1480	$quit->send;
965	});	1481	});
966		1482
967	$quit->wait;	1483	$quit->recv;
968		1484
969		1485
970	=head1 BENCHMARKS	1486	=head1 BENCHMARKS
971		1487
972	To give you an idea of the performance and overheads that AnyEvent adds	1488	To give you an idea of the performance and overheads that AnyEvent adds
…		…
974	of various event loops I prepared some benchmarks.	1490	of various event loops I prepared some benchmarks.
975		1491
976	=head2 BENCHMARKING ANYEVENT OVERHEAD	1492	=head2 BENCHMARKING ANYEVENT OVERHEAD
977		1493
978	Here is a benchmark of various supported event models used natively and	1494	Here is a benchmark of various supported event models used natively and
979	through anyevent. The benchmark creates a lot of timers (with a zero	1495	through AnyEvent. The benchmark creates a lot of timers (with a zero
980	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1496	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
981	which it is), lets them fire exactly once and destroys them again.	1497	which it is), lets them fire exactly once and destroys them again.
982		1498
983	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1499	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
984	distribution.	1500	distribution.
…		…
1001	all watchers, to avoid adding memory overhead. That means closure creation	1517	all watchers, to avoid adding memory overhead. That means closure creation
1002	and memory usage is not included in the figures.	1518	and memory usage is not included in the figures.
1003		1519
1004	I<invoke> is the time, in microseconds, used to invoke a simple	1520	I<invoke> is the time, in microseconds, used to invoke a simple
1005	callback. The callback simply counts down a Perl variable and after it was	1521	callback. The callback simply counts down a Perl variable and after it was
1006	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1522	invoked "watcher" times, it would C<< ->send >> a condvar once to
1007	signal the end of this phase.	1523	signal the end of this phase.
1008		1524
1009	I<destroy> is the time, in microseconds, that it takes to destroy a single	1525	I<destroy> is the time, in microseconds, that it takes to destroy a single
1010	watcher.	1526	watcher.
1011		1527
…		…
1107		1623
1108	=back	1624	=back
1109		1625
1110	=head2 BENCHMARKING THE LARGE SERVER CASE	1626	=head2 BENCHMARKING THE LARGE SERVER CASE
1111		1627
1112	This benchmark atcually benchmarks the event loop itself. It works by	1628	This benchmark actually benchmarks the event loop itself. It works by
1113	creating a number of "servers": each server consists of a socketpair, a	1629	creating a number of "servers": each server consists of a socket pair, a
1114	timeout watcher that gets reset on activity (but never fires), and an I/O	1630	timeout watcher that gets reset on activity (but never fires), and an I/O
1115	watcher waiting for input on one side of the socket. Each time the socket	1631	watcher waiting for input on one side of the socket. Each time the socket
1116	watcher reads a byte it will write that byte to a random other "server".	1632	watcher reads a byte it will write that byte to a random other "server".
1117		1633
1118	The effect is that there will be a lot of I/O watchers, only part of which	1634	The effect is that there will be a lot of I/O watchers, only part of which
1119	are active at any one point (so there is a constant number of active	1635	are active at any one point (so there is a constant number of active
1120	fds for each loop iterstaion, but which fds these are is random). The	1636	fds for each loop iteration, but which fds these are is random). The
1121	timeout is reset each time something is read because that reflects how	1637	timeout is reset each time something is read because that reflects how
1122	most timeouts work (and puts extra pressure on the event loops).	1638	most timeouts work (and puts extra pressure on the event loops).
1123		1639
1124	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1640	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1125	(1%) are active. This mirrors the activity of large servers with many	1641	(1%) are active. This mirrors the activity of large servers with many
1126	connections, most of which are idle at any one point in time.	1642	connections, most of which are idle at any one point in time.
1127		1643
1128	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1644	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1129	distribution.	1645	distribution.
…		…
1131	=head3 Explanation of the columns	1647	=head3 Explanation of the columns
1132		1648
1133	I<sockets> is the number of sockets, and twice the number of "servers" (as	1649	I<sockets> is the number of sockets, and twice the number of "servers" (as
1134	each server has a read and write socket end).	1650	each server has a read and write socket end).
1135		1651
1136	I<create> is the time it takes to create a socketpair (which is	1652	I<create> is the time it takes to create a socket pair (which is
1137	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1653	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1138		1654
1139	I<request>, the most important value, is the time it takes to handle a	1655	I<request>, the most important value, is the time it takes to handle a
1140	single "request", that is, reading the token from the pipe and forwarding	1656	single "request", that is, reading the token from the pipe and forwarding
1141	it to another server. This includes deleting the old timeout and creating	1657	it to another server. This includes deleting the old timeout and creating
…		…
1214	speed most when you have lots of watchers, not when you only have a few of	1730	speed most when you have lots of watchers, not when you only have a few of
1215	them).	1731	them).
1216		1732
1217	EV is again fastest.	1733	EV is again fastest.
1218		1734
1219	Perl again comes second. It is noticably faster than the C-based event	1735	Perl again comes second. It is noticeably faster than the C-based event
1220	loops Event and Glib, although the difference is too small to really	1736	loops Event and Glib, although the difference is too small to really
1221	matter.	1737	matter.
1222		1738
1223	POE also performs much better in this case, but is is still far behind the	1739	POE also performs much better in this case, but is is still far behind the
1224	others.	1740	others.
…		…
1234		1750
1235		1751
1236	=head1 FORK	1752	=head1 FORK
1237		1753
1238	Most event libraries are not fork-safe. The ones who are usually are	1754	Most event libraries are not fork-safe. The ones who are usually are
1239	because they are so inefficient. Only L<EV> is fully fork-aware.	1755	because they rely on inefficient but fork-safe C<select> or C<poll>
		1756	calls. Only L<EV> is fully fork-aware.
1240		1757
1241	If you have to fork, you must either do so I<before> creating your first	1758	If you have to fork, you must either do so I<before> creating your first
1242	watcher OR you must not use AnyEvent at all in the child.	1759	watcher OR you must not use AnyEvent at all in the child.
1243		1760
1244		1761
…		…
1252	specified in the variable.	1769	specified in the variable.
1253		1770
1254	You can make AnyEvent completely ignore this variable by deleting it	1771	You can make AnyEvent completely ignore this variable by deleting it
1255	before the first watcher gets created, e.g. with a C<BEGIN> block:	1772	before the first watcher gets created, e.g. with a C<BEGIN> block:
1256		1773
1257	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1774	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1258		1775
1259	use AnyEvent;	1776	use AnyEvent;
		1777
		1778	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1779	be used to probe what backend is used and gain other information (which is
		1780	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1781	$ENV{PERL_ANYEGENT_STRICT}.
		1782
		1783
		1784	=head1 BUGS
		1785
		1786	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1787	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1788	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1789	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1790	pronounced).
1260		1791
1261		1792
1262	=head1 SEE ALSO	1793	=head1 SEE ALSO
1263		1794
1264	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1795	Utility functions: L<AnyEvent::Util>.
1265	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1796
		1797	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1266	L<Event::Lib>, L<Qt>, L<POE>.	1798	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1267		1799
1268	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1800	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1269	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1801	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1270	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1802	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1271	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1803	L<AnyEvent::Impl::POE>.
1272		1804
		1805	Non-blocking file handles, sockets, TCP clients and
		1806	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1807
		1808	Asynchronous DNS: L<AnyEvent::DNS>.
		1809
		1810	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1811
1273	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1812	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1274		1813
1275		1814
1276	=head1 AUTHOR	1815	=head1 AUTHOR
1277		1816
1278	Marc Lehmann <schmorp@schmorp.de>	1817	Marc Lehmann <schmorp@schmorp.de>
1279	http://home.schmorp.de/	1818	http://home.schmorp.de/
1280		1819
1281	=cut	1820	=cut
1282		1821
1283	1	1822	1
1284		1823

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